THE UNIVERSITY OF ILLINOIS LIBRARY SVA "wi G \S -\T280 30 — Sulphur .74% Total 74.7%. Total 1 1.820 12,040 Fixed Carbon 84.3% Combustible matter 80.9 Fixed carbon Theoretic yield, B. t u: 1 1,730 m 1?'; Moisture 2 . 8 % 2- 1 Ash 10.7% Fixed carbon 72.% 1l'.7% Total 82.6% Carbon in volatile 0%*t-h*0 0*0 10 co-**o O CO O > ft £ ® a 1 o-si . 4J' H CO * ® .OK .S^ftft £ft®.g ft d Khm §j|z 6^0 © d,2ft:: O ft-g^ P-T ° § a> ! g O •S’® Ss to ioi Hi I o Pm §3:§ 5 d O © c3 © - © 10 |b a 5 gd^' 2 * oft -° k>,aq & oo cj O © rr ft w 4ss-»Sd ft2§l. e S cS, w ft+jft; ft^, C ©^ Sa S sa ft c3 - rr 02 '~ CC Qo 1 " .8g S's ©ftcssB g-a fl -.aft-s ®-| © |ft|a^S5 s g< 3 3 £ 2.2 2 © 2 S 8 8n§<&f*g£ w W CQ 30 05 O H M Ohm as; d * ggg o * * ooS sag S3&S sag d • • ' *rH £3 : gg : 823 : S?g i £85 : gg i aa : 05 • g3£ ggg 3<§s gsss £g§ a£g sag gg 3 Nci'ji co co d cococo i— Ji— 5eo S : i 3 : : S : : g : j 05 • • ^ : : ^ : : tC • • r-HMCO HNCO i-HiMCO t-hiNco < < -4 < ^ g -dcs . ■£B£ S cl 9 WtS 3 o llj 5.9 A ’S d *d fl © o .M-P O g >9 'g 9 d o i-H • ccTcoW CO o cd l>- 1—1 100. 00 "d L- O « °» 0 7.96 4. 95 76. 22 10. 87 O O | Red. 15.39 10 7. 62 5. 42 74.40 12. 56 100. 00 .28 13. 72 2.25 6.46 79. 59 11.70 100.00 .643 Red. 12.32 CO 3. 18 4.43 75. 97 16. 42 100. 00 .258 Red. 17.14 (NHCO^ 10 CO ft .9 a ■ga* s'a © © te*P ^ 03 % © C3 © 03 “ P,£> C3 © 03 ^ta *PP © tap «9 © ... P'0 p-2 P 2 o PI St g £ © I CO ^ © CO S§ wj +3 •5*3 S pi O o s ® fcb gS .2 Sjj£ § g g 'T 5 q, .r4 £88 «2 ppg O o* io 2 £ »Om oo+ 3 .g -*P -i-5 l-H O >"< ^8ft «o« 5 z; ^o.g £fS ill n ^ Ph o > C/2 7* 4) T* pSI hO Pl-^ w * . 2 w aSg Ml -4-5 ^ d 2 P 9 S o3 « > ° <1 ®rrt' OOOHNNN O C d O ^ * a eg 5 c3 © ;> ra 8p o .9J .S a Po zZ&M MM a*'!"©© glgrsp.gsjg ® ° 3r § ftS “• sjj © g S , a - a ~£ 1 ^- 3.2 0 0 3^5 S ©&p 2 © s ” 5 a •S'S © £ a “ So® 35! Stl g'g'S" B-Sg g * „ 2*0 a „ S go 2 p ^ ? -• ® cl 7a > 8=1 ’fto © t ^£9- c3 I C fe- © t? pjo“ p(V - — 0 n ca 50 o sse § ,: 3 s o ®to©a p| 9 Sl|gS|a* p|Sbi®s©*s^*i‘§ WW M»,0 ® “O ftp, '■sf^SSsSSSIS g P w ho 8 ® Jt o da in S 356 ® 2 ^’ fU|os! OO § § 03 > « 3 Pt) 9-^0 WfflcQGQ <1 as «o CHARACTER OF THE COAL. 29 Analyses of coals from Portsmouth , II. I., and Mansfield, Mass., by Jackson. a Water and volatile matter. Fixed carbon. Ash. Portsmouth, R. I., coal, clean, free from rust 10.0 84.5 77.0 5.5 Portsmouth, R. I., rusty coal 7.0 16.0 3.66 Portsmouth, R. I., rusty coal, “best quality*’ • 10.5 85.84 Portsmouth, R. I., coal, solid, grayish-black, and glossy but not graphitic. . Mansfield, Mass., Skinner mine 13.0 6.2 77.5 87.4 9.5 6.4 Mansfield, Mass., Hardon mine ' 6.0 92.0 2.0 Do 6.0 90.0 4.0 a Jackson, C. T., op. cit. These analyses of Mansfield coal must be interpreted in the light of recent analyses of Portsmouth coal. They suggest that the coal at Mansfield has a little higher percentage of fixed carbon than that at Portsmouth and possibly is more graphitic. Jackson reports a comparative test for ash of Portsmouth and Lackawanna coal by Christopher Rhodes, jr. In the first test 33,477 pounds of Lackawanna coal yielded 2,566 pounds of ash, or 7.66 per cent; in the second test 32,344 pounds of the same coal yielded 2,489 pounds of ash, or 7.69 per cent. On the other hand, 8,705 pounds of Portsmouth coal yielded 1,332 pounds of ash, or 15.3 per cent. Analyses of anthracite and bituminous or semibituminous coals from Pennsylvania , Virginia , and West Virginia .< Pennsylvania. 30 RHODE ISLAND COAL. Heating value. British thermal units. 12,047 12, 737 15,287 15,390 12,577 12,933 14,873 13,298 13,682 14, 882 12, 523 12, 818 14, 855 13,351 13,810 15,248 14,465 14,999 15,660 14,510 14, 850 15,690 14,279 14,800 15,890 16,013 Calories. 6,693 7,076 8,493 8, 550 6,987 7,185 8,263 7,388 7,601 8, 268 6,957 7,121 8,253 7,417 7,672 8,471 8,036 8,333 8,700 8,060 8,305 8, 715 7,933 8,222 8,828 8,896 Air-dry- ing loss. 3.4 1.6 1.5 1.5 2.6 ! 2 - 4 2.1 2.9 Ultimate. Oxygen. cOt^CMcO ^ICOO OCOCO HHO CO 00 r- < CiMt^t'- CO . 00 Oi © 1.37 1.41 1.48 1.26 1.31 1.40 1.42 Carbon. 72. 65 76. 81 92.19 93.05 79. 22 81.47 93.70 84.36 86.78 94.39 78. 96 80.82 93.68 81.35 84.15 92. 91 82. 79 85.30 89.53 80.70 83.64 89.80 90. 75 Hydro- gen. 3.10 2.64 3.17 3.20 2.23 1.97 2. 27 1.89 1.63 1.77 2. 13 1.91 2.21 3.08 2. 80 3.09 OHIO CO CM ^ Ci O 00 o lO CO co co id ^ id '"tf T* Tji* Sulphur. 0.74 .79 .95 tHCOt* Oi o »ON^ o g §33 -a o t “ , a) ■ 32 ? © . t > O .92 ; 38 3 O* 05 Ci l-H lO to »o West Virginia, CHARACTER OF THE COAL. 31 C ^ CO oo'oo'oo' o> o OH 329 / -9328 933! x = As received o = Air dried . • -Ash and moisture free Numbers are those of laboratory samples 933< 1 v/ 4 /93; 6X9 9335 771 337 7771 o/ o: 932S (3fK ’"771'i ®932 '72 8 77 7Z £ 3337 77< j9p/ 9379 7 77 -7-7-rr» 7700 , -fyr >337 6 93 30 n J( / / / Ux fO 93 9331 >5 336 9336 / xg 335 9 330* 60 50 40 6,000 7,000 8,000 9,000 10,000 11,000 12,000 13,000 14,000 Heat value in British thermal units Figure 3.— Chart showing relation of carbon in Rhode Island coal to fuel value. seems to be derived entirely from the fixed carbon. As a matter of fact, the calorific value of Rhode Island coal can be readily com- puted within probably 1 per cent by multiplying the percentage of fixed carbon by 144. Thus, if the percentage in one one-hundredth of a pound be multiplied by 14,400, it will be found to be generally a little higher than the actual figure obtained in the calorimeter. Thus in sample 9328 (p. 26) the fixed carbon is 64.43, and 0.6443 X 14,400 gives 9,278 British thermal units, as compared with 9,230 obtained in the calorimeter. In sample 9330 (p. 26) the fixed carbon in a pound, 0.4254, multiplied by 14,400 gives 6,025 British thermal units, as compared with 5,976 obtained in the test. In sample 9331 (p. 26) the fixed carbon should yield, by the above method of computation, 8,405 British thermal units, whereas the test gave 8,528; here the actual value is slightly above the value CHARACTER OP THE COAL. 37 as computed. Figure 3 shows the relation between the fixed carbon and the British thermal unit value as determined. The chart shows first that the fixed carbon of the coal, whether from Portsmouth or Cranston, has an almost uniform heat value and that the heat value is expressed as stated above by a little below 144 British thermal units for each per cent of fixed carbon in the coal. The line expressing the average ratio as drawn has the ratio 1:143. BEHAVIOR OF RHODE ISLAND COAL TOWARD MOISTURE. The presence of such a high percentage of moisture in so hard a coal has always excited a peculiar interest. In this connection it was pointed out by Emmons in 1884 that the Portsmouth coal, at least, possessed the striking peculiarity of quickly taking up a large percentage of water under a moist condition of the atmosphere and as readily parting with it under a drier condition of the atmos- phere. Emmons describes the following interesting experiments conducted by Gooch : 1 A sample of Portsmouth coal, * * * powdered and exposed for 24 hours in the balance room during the prevalence of a northwest wind, contained after exposure water amounting to 0.65 per cent of its weight when dried at 115°. Water (per cent). The dried (at 115° C.) coal took up during 24 hours’ exposure in the balance room, while the same wind was blowing, of its own weight 0. 15 After 16 hours’ exposure over water it had taken up 8. 46 After 24 hours’ exposure over water it had taken up 9. 72 After 61 hours’ exposure over water it had taken up 12. 64 After 85 hours’ exposure over water it had taken up 12. 67 The percentage of water fell: After 24 hours’ exposure over H 2 S0 4 to 1. 38 After 48 hours’ exposure over H 2 S0 4 to 54 After 138 hours’ exposure over H 2 S0 4 to .64 A similar sample was wet thoroughly, dried with filter paper, and exposed 24 hours in the balance room during a northwest wind. Its content of water in terms of coal dried at 115° C. amounted to 0.75 per cent. Water (per cent). A sample of the drill core from Portsmouth (see analyses 5,6, and 7, p. 28), moistened thoroughly, dried with paper, and exposed 24 hours during a northwest wind, contained, in terms of mate- rial dried at 115° C 0. 81 The dried coal took up during 24 hours’ exposure in balance room. . . 22 It took up over water, in 16 hours 8. 96 It took up over water, in 24 hours 10. 32 It took up over water, in 61 hours 12. 88 It took up over water, in 85 hours 13. 80 1 Emmons, A. B., Notes on the Rhode Island and Massachusetts coals: Am. Inst. Min. Eng. Trans., vol. 13, pp. 512-513, 1885. 38 RHODE ISLAND COAL. The coal contained of water, expressed in terms of itself dried at 115° C.: Water (per cent). After 24 hours’ exposure over 0. 85 After 48 hours’ exposure over H 2 S0 4 53 After 138 hours’ exposure over H 2 S0 4 46 A sample of the same piece, exposed in the balance room without wetting, contained of water 0.72 per cent of the weight of the coal dried at 115° C. A sample of the same piece, exposed in the balance room without wetting or drying in the air bath, contained of water, expressed in terms of itself dried at 115° C.: Water (per cent). After 16 hours’ exposure over water 11. 45 After 21 hours’ exposure over water 13. 26 After 37 hours’ exposure over water 16. 77 After 61 hours’ exposure over water 16. 91 After 85 hours’ exposure over water 16. 87 After 109 hours’ exposure over water 16. 85 The content of water expressed in percentage of coal dried at 115° C. : After 24 hours’ exposure over H 2 S0 4 , fell to 1. 84 After 48 hours’ exposure over H 2 S0 4 , fell to 83 After 138 hours’ exposure over H 2 S0 4 , fell to 71 For the sake of comparison, a piece of Pennsylvania anthracite was taken from the cellar and similarly treated. As it came from the bin it contained of water 4.69 per cent of the weight of the coal dried at 115° C.: Water (per cent) . Powdered and dried at 115° C., it contained 4. 42 After 26 hours’ exposure over water 5. 91 After 75 hours’ exposure over water 6. 34 After 144 hours’ exposure over water 5. 10 A similar piece (i. e., not powdered), exposed over water without previous drying in air bath, contained, in terms of weight of coal dried at 115° C.: Water (per cent.) After 30 hours’ exposure over water 5. 38 After 80 hours’ exposure over water 5. 67 After 150 hours’ exposure over water 5. 69 After 23 days’ exposure over water 5. 38 A piece of Cumberland bituminous coal contained, as it came from the bin (the. sample was powdered), in terms of the coal dried at 115° C 1.38 After 26 hours’ exposure over water 1. 98 After 75 hours’ exposure over water 2. 06 After 144 hours’ exposure over water 1. 95 UTILIZATION OF RHODE ISLAND COAL. KINDS OF USE. Rhode Island anthracite may be employed for household use, steam production, metallurgic work, briquetting, brick burning, arid similar work, the manufacture of water gas or producer gas for use directly or for power production to be transmitted electrically to UTILIZATION OF THE COAL. 39 centers of distribution. The graphitic portions of the beds may be used for foundry facings and furnace linings. Its suitability for building chimneys and other uses had been suggested at an early date, as indicated in Bryant’s poem “ A medi- tation on Rhode Island coal.” Its successful household use at that time (before 1832) is indicated by the beginning of the poem: I sat beside the glowing grate, fresh heaped with Newport coal. That the difficulties of its burning had been fully appreciated are also indicated toward the end of the poem, where he says: Thou shalt be coals of fire to those that hate thee, And warm the shins of all that underrate thee; Yea, they did wrong thee foully — they who mocked Thy honest face, and said thou wouldst not burn; Of hewing thee to chimney pieces talked, And grew profane, and swore, in bitter scorn, That men might to thy inner caves retire, And there, unsinged, abide the day of fire. HOUSEHOLD USE. Rhode Island coal has always been used in a small way for house- hold heating and some householders are said to have used it for 40 years or more. Samuel Sanford, who was well acquainted with the Portsmouth mines in the seventies, says that Portsmouth coal was then selling at the mine at $3.50 a ton and that a small amount was purchased and hauled away for household use, but that 90 per cent of the people living in the neighborhood preferred to burn Pennsyl- vania anthracite, costing at that time from $5.50 to $7.50 a ton. This condition has apparently prevailed during the whole history of the field. In burning the coal is said to ignite very slowly and to snap vio- lently and explode, tending to throw pieces of the coal out of the fire, but when once well ignited it burns very much like anthracite and gives an intense heat. The ash is said to have almost the same bulk as the coal and as a rule to fuse and clinker badly. The intense heat is said to be destructive to stoves and utensils and the clinkering tends to destroy the grate bars. Probably as a result of this rapid burning it is said to burn itself out quickly and to require much more attention in firing and in keeping overnight than other coals. It is said that by breaking the coal down fine and carefully screen- ing it to remove dust it ignites more easily, as it will after thoroughly drying, which also prevents the snapping of the coal when first heated. The existence of films of graphite in the coal along planes of slip- ping has been thought to be partly the cause of the slow ignition of the more graphitic coal. The breaking up of this coal aids in its ignition, it is supposed, by allowing freer passage of the heat. 40 RHODE ISLAND COAL. In general, as compared with other anthracites and bituminous coals, as shown both by the tests in the laboratory and under the furnace, Rhode Island coal has only from 70 to 80 per cent of the heat- ing power of other anthracites and from 60 to 70 per cent of the heat- ing power of bituminous coals shipped into New England. Indeed, the poorer samples of Rhode Island coal show only about 40 per cent of the heating efficiency of competing coals. This fact, together with its slower ignition, its destructively hot fire, and the fact that it yields a maximum of eight times as much ash as competing coals and requires more frequent attention, fully explains its unsuccessful use for household heating in the past. It is the misfortune of Rhode Island coal that it must compete with the best coals of the United States, which are brought into its market by boat at very low rates. At least two attempts have been made to briquet Rhode Island coal commercially, both of them by the Zwoyer process. Appar- ently neither attempt proved successful. Whether the process or the binder had anything to do with the lack of success is not known. It is claimed that the briquets first made, in 1898, fell to pieces, owing to the binder burning out before the coal became ignited, and the briquets made recently are said to have yielded dense volumes of smoke and soot that soon clogged the flues and chimneys. It may be doubted whether any of the binders in common use to-day will prove satisfactory in the household stove, in which the temperature is relatively low as compared with that of the furnaces under steam boilers for power. Experiments have since been made at Ports- mouth, and the results of tests by the Bureau of Mines indicate that it will be possible to make briquets that will be practically smokeless and that will stand handling. It appears possible that experiments will develop a process of making briquets, probably with some admix- ture of a high gas coal, that will give at least fairly successful results in household use. The experiments published by the Bureau of Mines were made at St. Louis in 1906 by what was then the technologic branch of the United States Geological Survey. No test was made of Rhode Island coal alone, but two tests were made of that coal mixed with two different bituminous coals from Pennsylvania in the form of briquets. The manufacture and character of the briquets is described under the heading “Briquetting tests” (pp. .46-48). The tests were made on a sectional steam boiler, such as is in common use for house heating. The detailed results of these tests are given in Bulletin 27 of the Bureau of Mines. The economic results only are repeated here. For the sake of comparison there are also given the results obtained by similar tests made in the engineering laboratory of the University of Illinois, at Urbana, 111., on anthracite, coke, and Pocahontas coal. UTILIZATION OF THE COAL 41 Results of tests of briquetted fuels in home-heating boilers at St. Louis, Mo., and TJrbana, III. Test number. Designation of fuel. Economic resi Equivalent evapo- ration from and at 212° F. per pound of fuel. alts (pounds). Fuel per hour per 100 square feet of radiating surface (mean load car- ried during test). As fired. Dry. As fired. Dry. St. L. 47 Pennsylvania No. 15 (one-half) and 6.55 6.94 4.57 4.57 Rhode Island No. 1 (one-half). St. L. 35 Pennsylvania No. 18 (one-half) and 7.13 7.34 4.19 4.14 Rhode Island No. 1 (one-half). Urb. 163 Anthracite 7.22 7.88 4.15 3.99 Urb. 185 Coke 7.98 8.37 3.75 3.61 Urb. 173 . Pocahontas 8. 24 8.98 3.65 3.58 Efficiency (per cent). Fuel at $1 per 2,000 pounds. Test number. Designation of fuel. Boiler and furnace (dry-fuel basis). Plant (fuel as fired basis). Cost in cents per 100 square feet of radiating surface per hour (mean load carried during test). Cost (in cents) of evaporating 1,000 pounds of water from and at 212° F. St. L. 47.... Pennsylvania No. 15 (one-half) and Rhode Island No. 1 (one-half). 52.01 49. 44 0.2290 7.64 St. L. 35.... Pennsylvania No. 18 (one-half) and Rhode Island No. 1 (one-half). 52.24 51.43 .2100 7.01 Urb. 163.... Anthracite 57.58 54.91 .208 6.92 Urb. 185.... Coke 62.50 61.44 .188 6.27 Urb. 173.... Pocahontas 57.60 53.92 .183 6.07 As far as the experiments were conducted it was — shown that the pitch binders used are not suitable for the furnace working at the low temperatures common in the household boiler, as they volatilize and in most cases escape unburned or were deposited on the surface of the boiler. This coating generally burned off once or twice a day, causing a high temperature in the flue and, as a con- sequence, danger of fire . 1 A test of “treated Rhode Island coal” by the Bureau of Mines, though not conclusive, failed, it is said, to show improvement in the burning or heating qualities of the coal. USE IN STEAM RAISING. The same qualities of the coal that are shown by household use are evident in its use in steam raising. (See description of action on grate in test 401, p. 45.) In this use its heat-giving value is of prime importance. The tests of the calorimeter show Rhode Island coal to 1 Snodgrass, J. M., Fuel tests of house-heating boilers: Univ. Illinois Bull. 31, 1909. 42 RHODE ISLAND COAL. have from 40 to 80 per cent of the heating value of competing coals. A number of careful commercial tests have been made, for one of which the general results are available. In 1874 a test of the Cranston coal was made at the pumping station of the Providence Waterworks. Unfortunately a table giving the detailed figures for the run has been lost, but the report which accompanied the table is still available. The following extracts from the report, a copy of which was furnished by the city engi- neer’s office, give the most complete and satisfactory demonstration of the steaming qualities of the coal that has been found. The report in part is as follows : CRANSTON COAL. The Cranston coal used at Pettaconset is a lusterless anthracite, containing graphite, quartz, and traces of asbestos and sulphur among its impurities. It yields about 26 per cent of ash. Its specific gravity is 2.30 and weight 64.75 pounds (? 133.75 pounds) to the cubic foot. Its evaporation power is about 7.76 pounds of water from and at 212° per pound of coal, which is the same as 6.6 pounds of water from 60° to steam at 60 pounds. The Lackawanna coal is a brilliant anthracite, containing about 18 per cent of ash. Its specific gravity is 1.60 and weighs 52.82 pounds (? 99.8 pounds) to the cubic foot. Its evaporative power is about 10.74 pounds of water from and at 212° per pound of coal, which is the same as 9.10 pounds of water from 60° to steam at 60 pounds. The evaporative power of the Cranston coal is therefore about 72 per cent of the Lackawanna. The following explanation of the lost table is given: Line 7. Rate of delivery is based upon the number of strokes during the run or experiment, length of stroke as observed, and a deduction of 2J per cent from the theoretical discharge of the pump. This percentage of loss is established by repeated weir measurements during former experiments. * * * Line 22. The rate of combustion is based on the coal used during the experiment. Line 23. In making up the total amount of fuel used during the day a small amount of coke was charged as Lackawanna coal, and the wood as equal to one-half its weight of coal. Lines 24 and 25 are placed in juxtaposition to show the large amount of coal used in banking. Line 26. The percentage of ash is made up from the total fuel used during the day. It was dampened and weighed wet and so given in the table. The Lackawanna ash was found to weigh 78 per cent of the recorded weight when dry. The Cranston ash 95£ per cent. Lines 27 and 28. The water evaporated per pound of coal or combustible is based on the fuel recorded during the run or experiment, and is probably too large by so much as the coal charged to the run is too little. The figures previously given as the evaporative power, viz, 7.76 and 10.74, are a mean of the quantity evaporated during the run and during the day per pound of combustible. The water was measured with a meter, said meter being tested before and after the experiment and proper correction made. Line 29 is added as a check upon the quantity of water used during the different days. It will be observed that it was nearly uniform. Line 30. The length of stroke is a mean of quarter-hourly observations. UTILIZATION OP THE COAL. 43 Line 31 . The duty is based upon the theoretical discharge of the pump and the static head. While this does not give the engine full credit for its work for this trial, it was considered the least liable to error. It may be added , however, that other experiments have shown the friction head for pump, main, and check valves to be about 3.9 per cent of static head. * * * Line 35 is given to show the relative duty based upon the coal used during the day or week, which is probably the truest criterion of the value of the coal. Line 32, on column R, is taken as unity as a fair standard of comparison. It will be observed that columns M and N show the value of the Cranston coal about 72 per cent of the Lackawanna. Line 36 makes the basis of comparison with the water evaporated daily, but a mean was obtained as previously explained, viz, 72 per cent, which seems to agree with the duty, as it should. About 10 per cent of Lackawanna coal and a small portion of coke was used with the Cranston coal, to aid the fire when burning irregularly on the grate. Less of this was used as experience was gained in its use. It is probable that with care and skill no other coal need be used in connection with it. A large loss was due to the small coal, partially burned, falling through the grate; although an occasional effort was made to sift it and reuse it, no practical gain was made. It was thought that a slower rate of combustion would be favorable to the coal, and permission was given to the agent for the coal to burn it slower. January 28th and 29th, it will be observed, it was reduced a little, and a slight increase of duty obtained; but it seems that this diminished rate of combustion as recorded is prob- ably in part due to screenings of small coal deducted from the coal charged and also deducted from the ash, thus reducing the ash very much for those two days, but increasing it proportionately the next day. However, a slight increase of duty is seen for the 10-days’ run, where the rate of combustion is 10.16 pounds of coal per square foot of grate per hour over the first week’s run, where it was 10.56 pounds. As it was the effort of the agent to keep the engine up to the usual speed, and with very good result, it was necessary to increase the rate of combustion over the usual rate, viz, 7.30 pounds, in order to effect it. It seems very probable that a slower rate than was used would be advantageous. Steaming tests of Rhode Island coal from Cranston have been made by the United States Geological Survey and the Bureau of Mines on the coal alone and briquetted with other high volatile coals. Results of these tests are as follows: RHODE ISLAND NO. I. 1 Anthracite graphitic coal from Cranston, Providence County (near Providence), was designated Rhode Island No. 1. This sample was mined from surface workings at Cranston and commercially would be classed as run-of-mine coal. It was shipped under the inspection of J. S. Burrows and was used in making steaming test 401; also mixed with Utah No. 1 in steam tests (on briquets) 414 and 415, coking tests 141 and 157, and briquetting test 127; mixed with Utah No. 2 in steaming test 416 (on briquets) and briquetting test 133; mixed with Pennsylvania No. 15 in briquet- ting test 184; and mixed with Pennsylvania No. 18 in briquetting test 243. i Holmes, J. A., in charge, Report of the United States fuel-testing plant at St. Louis, Mo.: U. S. Geol. Survey Bull. 332, pp. 223-224, 1908. 44 RHODE ISLAND COAL. Chemical analyses of Rhode Island No. 1. Car sam- Steaming tests.** ple.® 401 414 415 416 Laboratory No 3216 Air-drying loss 2.00 Proximate: Moisture 2. 41 2.33 2.45 2.27 5.85 Volatile matter 4.92 2. 47 24.21 22. 20 25.20 Fixed carbon 73. 61 78. 72 62.60 65.29 59. 56 Ash 19. 06 16.48 10.74 10. 24 9. 39 Sulphur .07 .08 .41 .41 .85 Ultimate: Hydrogen .90 .67 2.95 3. 13 2. 94 Carbon 75. 10 79. 49 78.63 77.64 76.42 Nitrogen .17 .18 .74 .74 .73 Oxygen 4.70 2. 71 6.25 7.59 9.04 Ash 16. 87 11.01 10.48 9. 97 Sulphur .08 .42 .42 .90 Calorific value (as received): Determined- Calories 6,109 10, 996 British thermal units Calculated from ultimate analysis — Calories 6, 176 11,117 British thermal units a Sample from producer-gas test 113 (failure) treated as car sample. b Proximate analysis of fuel as fired; ultimate analysis of dry fuel figured from car sample. Steaming tests of Rhode Island No. 1 {briquets). Test 401. Test 414. Test 415. Test 416. Duration of test ...hours.. 8.05 5. 0 5.0 10.02 Heating value of fuel B. t. u. per pound dry fuel. .. 11,639 12,845 12,823 12,244 Force of draft: Under stack damper inch water. . 0.54 0.67 0.62 0.58 Above fire...! : .18 .21 .06 .20 Furnace temperature °F. . (®) 2,119 2.053 Dry fuel used per square foot of grate surface, per hour . . .pounds.. 20.22 18.42 19.01 21.51 Equivalent water evaporated per square foot of water-heatmg surface per hour 1.99 2. 96 3.25 2.78 Percentage of rated horsepower of boiler developed . . 55.8 83.0 91.0 78.0 W ater apparently evaporated per pound of fuel as fired . pounds . . 4. 19 6.75 7. 17 4.26 AVater evaporated from and at 212° F.: Per pound of fuel as fired ..pounds.. 4.81 7.86 8.36 4.95 Per pound of dry fuel ....do.... 4.93 8.05 8. 55 5.26 Per pound of combustible do 7. 70 9.35 9.75 7.70 Efficiency of boiler, including grate .per cent. . 40.91 60.52 64.39 41.49 Fuel as fired: Per indicated horsepower hour 5.88 3.60 3.38 5.71 Per electrical horsepower hour ....do.... 7.26 4.44 4.18 7.05 Dry fuel: Per indicated horsepower hour ....do.... 5.74 3.51 3.31 5.38 Per electrical horsepower hour 1 do 7.08 4.34 4.08 6.64 ® Too low to be read with Wanner optical pyrometer. Forced draft used on this test. Remarks: Tests 414 and 415 on briquets made from Rhode Island No. 1 and Utah No. 1 mixed. The briquets burned freely, with short, yellow flame; did not crack open, but coked throughout and held together well. No smoke; burned very much like anthracite, except for color of flame. These comparative tests on Rhode Island coal No. 1 gave only 55.8 per cent capacity and were unsatisfactory. (See test 401 above.) Heavy clinker, which was tough and plastic when hot and brittle when cold, but did not stick to the grate. Test 416 on briquets from test 133, made from Rhode Island No. 1 and Utah No. 2 mixed. With natural draft the briquets burned with a very short flame; with forced draft they burned with a longer flame, giving a hotter fire. Briquets did not coke or hold together well in the fire. No smoke; see briquetting test 127 for com- parative data. No clinker; a large amount of ash resulted, due to the crumbling of the briquets and the falling of the loose particles through the grate. UTILIZATION OF THE COAL. 45 In Bulletin 23 of the Bureau of Mines the following additional data are given on page 179 for test 401 and on page 191 for tests 414 to 416: Test No. 401 (No. 1). — The coal burned slowly, with a short, bluish flame. It became hot and fused together, cutting off the air supply through the grate. Hooking the fire helped slightly. Small pieces of coal burned more completely than large ones. About three-fourths inch coal would be the best size for steaming purposes. Large pieces burn only on the surface, because the ash fuses and adheres to the coal, thus insulating the inner portion. Low capacity was developed, owing to the fact that high enough draft could not be obtained with the fan blower. In order to develop the rated capacity, a draft of 3 to 4 inches of water would be necessary. A rocking grate would be preferable to a flat grate. Pressure was used in the ash pit. Auto- matic air admission was not operated. The furnace temperature was too low to be read by the Wanner optical pyrometer. Test No. 414 (briquets). — One-quarter of the observations of furnace temperature were too low to be read by the Wanner optical pyrometer. The average is not repre- sentative of the test. The briquets did not crumble in the fire and burned with a short flame. Automatic air admission was not operated. A heavy layer of plastic clinker formed on the grate. It was broken with some difficulty. Test No. 415 (briquets). — The briquets did not crumble in the fire and burned with a short flame. Automatic air admission was not operated. A heavy layer of plastic clinker formed on the grate. It was broken with some difficulty. Forced draft was used. Test No. 410 (briquets). — The briquets crumbled in the fire, did not cake, and burned with a long flame. Automatic air admission was not operated. A large amount of free ash formed on the grate. It was easily removed. Forced draft was used. For the sake of comparison there are given below figures from the tests by the Bureau of Mines at St. Louis, Mo., and at Norfolk, Va., showing, first, the horsepower developed and, second, the pounds of water evaporated per pound of fuel of Rhode Island coal on the one hand and of some of the competing coals on the other. Results of steaming tests by the Bureau of Mines on Rhode Island coal and other coals that are shipped into New England. Bureau of Mines designation. Coal. Location. Kind of sample. Horse- power developed on test. Pounds of water evaporated per pound of fuel equivalent from and at 212° F. 490 Md. No. 2 Georges Creek Frostburg Rim of mine . . 239.2 9. 87 237 Pa. No. 8 Cambria County. . Anthracite culm . . Ehrenfeld do 174.2 9.85 36 Pa. No. 3 Scranton Culm 184.5 8. 01 401 R. I. No. 1 do Cranston 117. 1 4. 81 46 W. Va. No. 12 Pocahontas No. 8. . Big Sandy Rim of mine . . 206.1 9. 74 56W.Va. No. 11 Pocahontas No. 3. . Zenith do 213.7 9.54 39 W. Va. No. 6 New River Rush Run do 213.2 9. 88 296 W. Va. No. 21 Kanawha Winifrede do 213.8 9.69 414 Utah No. 1 and R. I. Mixed Briquets 174.3 7.86 No. 1. 415 Utah No. 1 and R. I. do do 191.2 8.36 No. 1. 416 Utah No. 2 and R. I. do do 163.7 4.95 No. 1. 46 RHODE ISLAND COAL. According to these figures, Rhode Island coal alone yields from 54 to 68 per cent as much horsepower as the other coals listed and from 48 to 60 per cent as many pounds of water evaporated per pound of fuel. Lest it be thought that the highest figures have been selected for the competing coals, it may he mentioned that in other tests Pocahontas coal developed horsepower as high as 268 and New River coal as high as 367. As 20 tons of coal was used and every effort was made that the coal should be representative of that being regularly mined, the results may be accepted as accurate. As the car sample analysis of this coal (p. 44) shows it to have been above rather than below the average, it may be safely stated that, judged by analyses, calorimeter tests, and tests in actual practice, Rhode Island coal in making steam will yield from 40 to 80 per cent as many heat units as the coals with which it must compete to-day. USE IN METALLURGY. Rhode Island coal has been used successfully in the reduction of copper ore and in the metallurgy of iron, as already stated under the heading “ History of development.” At the time of its successful use anthracite coal was used in the blast furnace and the furnaces were much smaller than at present. To-day coke has been substi- tuted for anthracite and is being used exclusively. The furnaces have been enlarged both in size and output. No figures are at hand which would form the basis for a comparison of the availability of Rhode Island anthracite as compared with coke in the modern fur- nace, but a general consideration of the reasons for the use of coke in the modern furnace and its cost would suggest that Rhode Island coal could not compete with coke either in cost or availability. It is quite possible that for foundry use and in small reheating furnaces, under certain conditions, it might be still possible to use Rhode Island coal in spite of the cost. BRIQUETTING TESTS. In addition to the actual commercial tests of Rhode Island coal when made into briquets, the Bureau of Mines has made a number of briquetting tests with that coal. 1 The analyses of the coal used, both alone and mixed, will be given first, as none of the tests were made on the Rhode Island coal alone. Rhode Island No. 1 was from Cranston; Pennsylvania No. 15 was B or Miller coal from Wehrum, Indiana County; Pennsylvania No. 18 was the same coal from Lloydell, Cambria County; Utah No. 1 was from Huntington Creek, Carbon County; Utah No. 2 was from Coalville, Summit County. Holmes, J. A., op. cit., pp. 201 et seq. UTILIZATION OF THE COAL. 47 Analyses of coals used in briquetting tests. R.I. No. 1, car sam- ple. Pa. No. 15, car sam- ple. Pa. No. 18, car sam- ple. Utah No. 1, car sam- ple. Utah No. 2, car sam- ple. Half R.I. No. 1, half Pa. No. 15. Half R. I. No. 1, half Pa. No. 18. Half R. I. No. 1, half Utah No. 1. Half R.I. No. 1, half Utah No. 2. 3216 4082 4509 3199 3259 4913 2.00 2. 80 4.10 3.80 2.30 Proximate: Moisture 2.41 3.13 4.46 6. 05 12.66 0.74 1.34 2.45 5. 85 Volatile matter 4.92 17. 61 15.44 42.02 38.30 15.96 16.39 24.21 25.20 Fixed carbon 73.61 69.45 71.63 47.06 43.19 69. 71 70.34 62. 60 59.56 Ash 19.06 9.81 8.47 4.87 5.85 13.59 11.93 10.74 9.39 Su phur .07 3.77 1.49 .55 1.39 2. 61 1.37 .41 .85 Ultimate: Hydrogen .90 4.62 4.80 5. 76 3.05 3.46 2.95 2.94 Carbon 75. 10 76.41 77.43 72. 32 77.48 77.79 78.63 76.42 Nitrogen .17 1.14 11.28 1.38 .49 .53 .74 .73 Oxygen 4.70 4.25 6. 53 15. 12 2.C5 4.74 6.25 9.04 Ash 13. 70 12. 09 11.01 9.97 Sulphur 2. 63 1.39 .42 .90 Calorific value (as received) : Determined- Calories 6,109 7,664 7,601 7, 306 British thermal units 10,996 13, 795 13,682 13, 151 Calculated from ultimate analyses — Calories 6,176 7,189 British thermal units 11,117 12,940 The briquets are thus described. (See also pp. 43-44.) Test 184- — Pennsylvania No. 15 was mixed with an equal portion of Rhode Island No. 1 (run of mine) in this test. Excellent briquets were made with 6.25 per cent binder on the Renfrow machine. Although the pitch used had a low melting point, the briquets handled well from the machine, and piled without sticking. The outer surface was very hard and smooth, and broke without crumbling, giving a smooth fracture and sharp edges. Test 243. — Equal parts of Pennsylvania No. 18 and Rhode Island No. 1, both run of mine. An effort was made to improve the burning qualities by increasing the melting point of the binder, but owing to the hardness of the pitch used and insuffi- cient pressure, these briquets were not satisfactory. They could not be handled when warm without many being broken, but when cold were brittle, producing considerable slack in handling. No physical tests were made. Test 127 (Utah No. 1 with Rhode Island coal No. 1). — This test was made to prove the value of briquetting a good fuel with one that is commercially worthless. A high- volatile coal, low in ash, was chosen to mix with the graphitic coal. Various percent- ages were tried, but 47 per cent of each coal and 6 per cent binder made an entirely satisfactory briquet. Six per cent binder made excellent briquets; outer surface smooth and polished and very hard; briquets broke without crumbling, and broken surfaces were smooth and hard. Test 133 (Utah No. 1 and Rhode Island No. 1). — In this test Rhode Island No. 1, the only available high- volatile (carbon?) coal, was chosen in order to supplement the data of test 127. Test 133 was not successful, as coal showed characteristics of lignite, both in briquetting and burning. The mixture contained 47 per cent of each coal. Briquets with 6 per cent binder were tough and hard ; outer surface smooth and very hard; the fracture rough but clean and firm. No drop tests were made. 48 RHODE ISLAND COAL. The tests of the briquets gave the following results: Results of tests of briquets. Size as used: Over one-fourth inch One-tenth to one-fourth inch One-twentieth to one-tenth inch. . One-fortieth to one-twentieth inch Under one-fortieth inch Details of manufacture: Machine used Temperature of briquets Binder — Kind Laboratory No Amount Weight of— Fuel briquetted Briquets, average Ileat value per pound — Fuel as received Fuel as fired Binder Drop test (1-inch screen): Held Passed Tumbler test (1-inch screen): Held Passed (fines) Fines through 10-mesh sieve Weathering test: Time exposed Condition a Pennsylvania No. 15. per cent do.. do.. do.. do.. °F .per cent .pounds — do.. .per cent — do.. .per cent do.. .days Test 184. Test 243. Test 127. Test 133. 0.8 1.0 1.0 1.2 7.0 6.8 5.8 6.0 15.0 17.6 9.4 19.2 22.2 25.2 26.4 25.6 55.0 49.4 57.4 48.0 Renf. Renf. Renf. Renf. 185 185 149 149 w. g. p. w. g. p. w. g. p. w. g. p. 4543 4625 3410 3410 6.25 8.0 6 6 10,000 2,000 16,000 37,000 0.5 0.5 0.52 fa 13, 712 b 13,682 \c 10,996 c 10,996 12,259 11,032 12, 793 13,387 12,532 11,527 16,969 16,576 16,478 16,478 68.5 31.5 93.0 7.0 91.4 11 214 190 A B C b Pennsylvania No. 18. c Rhode Island No. 1. In these descriptions Renf. refers to the Renfrow machine; w. g. p. is water-gas pitch; the drop test consisted in dropping 50 pounds of the briquets in a box a distance of 6J feet onto an iron plate, screening each time what would go through a 17-mesh wire screen. In the tumbler test 50 pounds were revolved in the Opermayer tum- bler 56 times and then screened through 1-inch and -^inch mesh screens. Under “ Weathering test/’ A means unchanged; B, shape unchanged, surface pitted or dulled or edges worn; C, outside briquets weathered, fracture not sharp. House-heating tests were made for briquets described in tests 184 and 243 and steaming tests from briquets made in tests 127 and 133. These have been described under the headings “House heating” and “Steam raising.” BRICK BURNING AND SIMILAR WORK. The use of this coal for brick burning or the burning of limestone for fertilizers has been suggested. In this work the broken or fine coal is placed between layers of brick in a kiln or between layers of limestone when burned in piles in the fields. The writer does not know of such use having been made of the coal and is not prepared to predict how successful it would be. The ash apparently would UTILIZATION OF THE COAL. 49 not be a serious detriment in such use. The coal might also be used for the roasting of ores and in other work where the ash is not a serious detriment and high heat rather than long-continued heat is desired. INDIRECT USE AS WATER GAS OR PRODUCER GAS. There has been a widespread feeling for many years that Rhode Island coal would some day come to its own through its use in the production of water gas or producer gas for metallurgic work, or more especially for use in the gas engine in the production of electric power to be used for manufacturing near the mines or to be trans- mitted to the cities. Its possible use in the manufacture of water gas was mentioned by Shaler in 1899, who says “that a test of a few tons of the coal had been made in the manufacture of water gas and that it was well suited to the purpose.” 1 It has been thought that a few plants situated at the mines, by being specially designed and specially manned, would be able to deal with the peculiar char- acteristics of the coal satisfactorily and thus take advantage of its location in saving transportation costs. In principle producer gas is made by forcing air through a mass of incandescent coal so controlled that the oxygen of the air finds a surplus of carbon and unites to form carbon monoxide which is combustible and passed off with the nitrogen, which is inert, the product being known as producer gas. In the manufacture of water gas superheated steam is used in place of the air, and the product consists of hydrogen with carbon monoxide instead of the inert nitrogen. Water gas, therefore, yields about twice as many heat units as the same quantity of producer gas or, if enriched, from four to five times as many. Modern practice has tended toward the pro- ducer-gas plant as the most efficient method of transforming the power of the coal immediately into electric power, though with Rhode Island coal water gas may prove the better of the two. A number of tests have been made by the Bureau of Mines on Rhode Island coal in the producer-gas plant. Though it may be conceded that future tests may, and doubtless will, lead to changes in the construction of the producer-gas plant that will more fully adapt it to the peculiar behavior of Rhode Island coal and that with such an improved and specially devised plant better results would be obtained, yet the figures here quoted may be accepted as fairly indic- ative of the results obtainable with present forms of the producer. The results of the producer-gas tests are described in Bulletin 13 of the Bureau of Mines, and because of the interest in this phase of the problem the results of the tests are given in full. i Shaler, N. S., Woodworth, J. B., Foerste, A. F., Geology of the Narragansett Basin: U. S. Geol. Survey Mon. 33, p. 84, 1899. 97887°— Bull. 615—15 4 50 RHODE ISLAND COAL. The coal used in test 113 was mined from the Budlong pit, at Cranston, under the supervision of J. S. Burrows. The coal for tests 190 and 191 was later shipped from the same pit by Budlong & Son. It consisted principally of small lumps, 1 or 2 inches in size, and a few larger lumps were broken up by the hammer before firing and the fine material was screened out. Before making this test a little of it was tried in the blacksmith forge with the following result, as described in a preliminary report: 1 Before the testing was started a small quantity of this fuel was burned in a black- smith’s forge in order to note any special characteristics that it might exhibit while burning, and thus aid in the operation of the producer during the test. On the blacksmith’s forge it was very slow to ignite, but when well ignited it burnt very much like anthracite and gave an intense heat. When first fired, it snapped violently and frequently small lumps of coal were thrown forcibly from the fire. After burning for about half an hour in the forge there was a considerable amount of slag or clinker about the consistency of thick tar. Upon examination this slag did not appear to consist entirely of fused ash, but to contain quite a portion of the unburnt fuel in the fused state. Although the conditions in the blacksmith forge of heavy forced draft were unlike the conditions that would exist in the producer, it was expected that the tendency of the fuel to fuse would prevent to some extent its more successful use in the producer. The coal for test 194, amounting to about 20 tons, was obtained from the Portsmouth mine under the supervision of C. A. Fisher, of the United States Geological Survey. It was taken in the heading at the 800-foot level, about *1,200 feet south of the slope. At this point the coal was being mined and mining had extended about 50 feet beyond the face of the heading, which had been left when the mine was previously abandoned. The coal at this point, as described by Mr. Brown 2 — is some 65 inches thick, showing in the upper and lower portions of the coal bed some 2 or 3 inches of graphitic shaly material, which probably results from shear. The coal shows a considerable degree of purity, excepting near the middle of the bed where 1^ or 2 inches of “bone” with quartz and later pyrite occur. The bedding is rather thin, probably one-half inch, but in some cases there is a thick bed of some 8 inches of massive coal. Throughout the bed, increasing toward the edges of the roll, there occur numerous offset veins of quartz, sometimes reaching a thickness of 2 or 3 inches, but penetrating, in a large number of cases, in mere shreds and veinlets of silica. * * * No run-of-mine coal could be taken and the tests therefore are made upon the best coal that the mine can produce. The tests are described as follows : 3 Rhode Island No. 1, test 113. — Rhode Island No. 1 was a graphitic coal having a gray, metallic appearance. Some of the lumps were extremely hard, but others were soft. This material was charged on top of a good fuel bed of Tennessee coal capable of making a gas of average quality. As the charging continued, the heat value of the 1 Preliminary report of the natural resources survey of Rhode Island: Rhode Island Bur. Industrial Statistics Bull. 1 (Ann. Rept. 1909, pt. 3), p. 105, 1910. 2 Idem, pp. 95-96. a Bur. Mines Bull. 13, pp. 199, 342-346, 349, 1911, UTILIZATION OF THE COAL. 51 gas steadily decreased, whereas the temperature of the fuel bed increased. After 15 hours the calorimeter would not work because of the low-heat value of the gas, which, at that time, was about 55 British thermal units per cubic foot. Three hours later the engine stopped and subsequent attempts to start it again were unsuccessful. * * ***** Pittsburgh No. 19 A, test 190 . — The fuel used during this test was a Rhode Island graphitic anthracite. It was heavy and hard and a freshly broken surface presented a glossy appearance; it contained a large percentage of graphite and one could mark with pieces of the coal as readily as with a pencil. Because this fuel ignited slowly the coke bed was allowed to become thoroughly incandescent before any of the graphitic coal was charged, and while the fuel bed was being built up a maximum draft was maintained. About an hour after the first charge of coal was made the gas burned steadily at the test cock, and although it was low in heat value the engine was started. After running about 30 minutes, however, on no load it stopped, due to the poor quality of the gas. After the engine was started the draft in the producer decreased considerably on account of the small amount of gas consumed by the engine. With this reduced draft the fire died down and the gas decreased rapidly in heat value. Soon after the engine stopped the gas was discharged into the atmosphere, and with a good draft the fire soon began to improve; the gas, however, was of unsatisfactory quality for some time. The engine was finally started again, and in order to maintain a sufficient draft to produce combustible gas a portion of the gas was allowed to escape through the purge pipe. During the remainder of the day (about hours) the producer gave no trouble and a little over half of full load was maintained at the engine. At the close of the day’s run the producer was seem- ingly in good condition for the night’s shutdown. The fire, however, did not keep and the next morning it was necessary to rekindle it with wood. As is shown by the graphic log, the results obtained were more satisfactory after the first day’s trial. From one to two hours each morning were required to get the producer in condition to generate gas of sufficient heat value to start the engine, and at the close of each day ’s run the fire was banked with a good grade of coal in order to hold it over- night. Throughout the greater part of the test also a considerable portion of the gas was necessarily allowed to escape to the atmosphere in order to maintain the required draft. The quantity of gas thus wasted was difficult to estimate, and for this reason little value can be attached to the figures given in the table on page 357 [p. 53 of this paper] for fuel consumed per horsepower hour, since no allowance for this waste was made. Throughout the test the fuel bed increased rapidly in thickness, and at the end of the fourth day the producer was completely filled with fuel and refuse. One of the characteristics of this graphitic coal is that its ash occupies nearly the same volume as the original fuel. The resistance of the fuel bed was not excessive at any time and few shots were made. Throughout the run little trouble was experienced from clinker, although a considerable quantity formed and adhered firmly to the producer walls. Pittsburgh No. 19 A, test 191 . — A second test was made on Pittsburgh No. 19A in an attempt to reduce the waste of gas and thus obtain results that would be of more value than those obtained from test 190. Instead of kindling a fire on the coke bed, as in the preceding tests, 1,000 pounds of the graphitic coal, making a layer 1 foot thick, were first charged on top of the coke in the producer, and then the fire was started on top of this. The result of this change of procedure was satisfactory; gas of sufficient heat value to run the engine was generated in about an hour and a quarter from the time of starting the fire, and at the end of the test practically all of the coke was recovered. During the first three hours of the test no gas was discharged into the atmosphere, and consequently there was no waste; but at the end of this period the fire began to die out and the gas diminished in heat value. It was evident that the draft in the 52 RHODE ISLAND COAL. producer was too low; consequently a portion of the gas was allowed to escape, and soon afterwards the fuel bed was in much better condition and the heat value of the gas was considerably higher. Throughout the test it was frequently necessary to resort to this method of increasing the draft in order to generate gas of sufficient heat value to run the engine. Never- theless the quantity of gas thus wasted was much less than in the preceding test, and from the results given in the table it may be seen that the fuel consumption was also much less. On the other hand, the effort to operate with a minimum waste of gas resulted in a much lower average draft than in the preceding test, and the effect of this was to lower the heat value of the gas, and consequently to diminish the average load which could be carried at the engine. The thickness of the fuel bed increased rapidly, as in the preceding test, but during the last part of the run there was much more clinker formed than at any time during test 190. ******* Pittsburgh No. 62, test 194 • — Pittsburgh No. 62 was a graphitic anthracite from Rhode Island, having the same characteristics as Pittsburgh No. 19A. It behaved in a similar manner in the producer, being slow to ignite and requiring a good draft to generate a gas of fair quality. As in previous tests with this fuel, a part of the gas was wasted during much of the time, and for this reason little value can be attached to the figures for fuel consumption per brake horsepower-hour given in the table on page 357 [p. 53 of this paper]. This graphitic coal would not hold fire overnight in the producer, and in order to avoid rekindling each morning the fire was banked at the end of each day’s run with a good grade of bituminous coal, which held the fire satisfactorily. The coal thus used was reduced to its equivalent weight of graphitic coal and charged against the test. From to 2 hours each morning, after starting the producer, was required before a gas capable of running the engine was generated. Throughout the test the gas was rather variable in quality and the load carried was somewhat irregular, as is shown by the graphic log. A comparatively small amount of clinker formed during this run. Results of producer-gas tests made at Pittsburgh, Pa. Duration of test Proximate analysis of fuel (per cent): Moisture Volatile matter Fixed carbon Ash Sulphur, separately determined ' Fuel charged in producer (pounds ): a Total— As fired Dry Combustible Per hour — As fired Dry Combustible Per square foot of fuel-bed area per hour— As fired Dry Combustible — . Refuse: Total (determined by weight) Combustible in refuse— Total Per cent hours. pounds. . No. 19A, Auburn, R. I. 22.33 3.70 2.11 71.45 22. 74 .06 11, 335 10,916 8,339 507.6 488.8 373.4 39.2 37.7 28.8 3,000 1,648 55.0 No. 19A, Auburn, R. I. 29.00 4.80 2.50 69.90 22.80 .10 9, 454 9.000 6,844 326.0 310.3 236.0 25.2 24.0 18.2 2,138 845 39.5 No. 62, Ports- mouth, R. I. 32. 17 11.50 3.41 63.59 21.50 .59 11,334 10,031 7,594 352.3 311.8 236.1 27.2 24.1 18.2 2,815 551 55.1 a Figures given include the fuel equivalent of coke consumed during test. UTILIZATION OF THE COAL. 53 Results of producer-gas tests made at Pittsburgh , Pa. — Continued. No. 19A, Auburn, R.I. No. 19A, Auburn, R. I. No. 62, Ports- mouth, R.I. Combustible consumed: Total pounds.. 6,691 80.2 5,999 87.7 6,043 79.6 Coke in fixing bed (pounds): 813 1,017 989 1,435 673 166 647 28 762 Calorific value (British thermal units): Fuel per pound— 10, 121 10,090 10, 590 10,440 10,523 13,898 3,777 4,262 101.0 10, 510 13, 759 13,930 3,996 4,205 94.7 Standard gas— From 1 pound of fuel — 2,587 2,696 99.1 Dry Consumed per horsepower hour— 9,296 11,258 10,076 12,548 15,010 8,989 10,757 12, 625 Electrical 13,319 21,919 5,993 4,950 4,187 Equivalent to stated horsepower per minute — Gas 21,737 22,161 6,269 5,489 4,407 5, 238 4,462 3,682 399,379 13,772 42.2 Standard gas produced (cubic feet) — Total 296,348 13,271 26.1 423,526 13,165 37.4 Per pound of fuel charged — As fired Dry 27.2 44.4 42.2 Combustible 35.5 58.4 55.8 Standard gas consumed by engine (cubic feet): Per hour 13,261 93.8 13,762 106.4 13,155 Per horsepower hour — Indicated Brake 113.6 132.5 106! 5 Electrical 134.4 158.5 125.0 Composition of gas (per cent of volume): 6.98 7.24 5. 08 0 2 . 2 . .13 .06 .08 C2H4 .00 .00 .00 CO 23.25 22.74 24. 91 h 2 6.33 5. 28 4. 66 CH* .38 .34 .43 N 2 62.93 1,015 45.5 64.34 1,054 36.3 64.84 Water used: Vaporizer (pounds)— Total ol53 Per hour Per pound of fuel fired .09 .11 Wet scrubber (cubic feet) — Total 6,296 282 4,503 155 5,371 167 Per hour Per 1,000 cubic feet standard gas 21.3 11.3 12.7 Engine jackets (cubic feet) — Total 2, 557 3,382 121 2,866 89 Per hour 115 Per brake-horsepower hour .98 1.16 .72 Entire plant (cubic feet)— Total 8,869 397 7,902 273 8,239 256 Per hour Per brake-horsepower hour 3. 40 2.62 2.07 Average barometric pressure (inches of mercury) 29.18 29. 12 29.20 Average pressure (inches of water): Gas leaving producer — 6.21 — 6.99 —4. 77 Gas leaving economizer — 6.57 — 7.24 —5. 09 Gas leaving wet scrubber -10. 68 —10. 04 —7.59 Gas entering dry scrubber + 5.55 + 2.97 + .62 + 6.04 + 2.93 + .39 103 +6.14 +3. 37 +1.85 64 Gas entering meter Gas leaving meter Average temperatures (°F.): Air entering economizer 110 Air and vapor entering producer 391 363 400 Gas leaving producer 1,214 1,048 1,180 Gas leaving economizer 616 543 516 54 RHODE ISLAND COAL, Results of producer-gas tests made at Pittsburgh , Pa. — Continued. Average temperatures (°F.) — Continued. Gas leaving wet scrubber Gas entering meter Jacket water: Entering Leaving Gas horsepower Revolutions per minute of gas engine Explosions per minute per cylinder Indicated horsepower, total Brake horsepower: Developed at engine Commercially available Electrical horsepower: Developed at switchboard Commercially available Average electrical horsepower required to run auxiliary machinery Economic results: Fuel charged in producer per horsepower hour (pounds): Per indicated horsepower developed — As fired Dry Combustible Per brake horsepower— Developed at engine— As fired Dry Combustible Commercially available — As fired Dry Combustible Per electrical horsepower — Developed at switchboard — As fired.. Dry Combustible Commercially available— As fired Dry Combustible Efficiency (per cent): Of conversion and cleaning gas Of producer plant Thermal, based on stated horsepower and gas horsepower- indicated Brake Electrical Of entire plant, based on fuel charged per stated horsepower per hour— Brake horsepower developed at engine Brake horsepower commercially available Electrical horsepower developed at switchboard Electrical horsepower commercially available No. 19A, Auburn, R.I. No. 19A, Auburn, R.I. No. 62, Ports- mouth, R.I. 81 80 47 85 85 43 72 76 39 137 135 119 516. 8 512.5 522.5 261.2 260.7 268.8 130. 6 130.4 134.4 141.3 129.4 147.8 116. 7 103.9 123.5 113.4 100.7 120.1 98.7 86.8 105.2 95.9 84.1 102.3 2.8 2.7 2.9 3.59 2.52 2.38 3.46 2.40 2.11 2.64 1.82 1.60 4.35 3.14 2.85 4.19 2.99 2.52 3.20 2.27 1.91 4.48 3.24 2.93 4.31 3. 08 2.60 3.29 2.34 1.97 5.14 3.76 3.35 4.95 3.57 2.96 3.78 2.72 2.24 5.29 3.88 3. 44 ■ 5. 10 3.69 3.05 3189 2.81 2.31 •25.6 39.7 36.2 25.5 39.4 36.0 27.3 25.3 28.3 22.6 20.3 23.6 19.1 16.9 20.1 5.8 8.0 8.6 5.6 7.8 8.3 4.9 6.7 7.3 4.8 6. 5 7.1 In order that comparison may be made with the results of tests of other coals there is given a supplementary table/ showing the pounds of fuel of Rhode Island and some other coals charged in the producer per commercial brake horsepower and electric horsepower, as that forms the best basis for comparison. 1 Bur. Mines Bull. 13, p. 357, 1911. Economic results of Rhode Island coals as compared with certain other coals of the United States when used in producer-gas plant. UTILIZATION OF THE COAL, 55 Fuel charged in producer per horsepower-hour (pounds). Per electric horsepower. Commercially available. Com- bus- tible. HHrtlNHHrHHrtHHrtlNINNHNINWNHciN Dry. s&gssgsgggg&sssssssggss ^^^co^^i-H*-t^T--iffqc^c4eceo ipieo' ic4pi • Developed at engine. Com- bus- tible. 3S8gg£g£3k3kggSSgS;gS;S£o: ^ r4 ,-i r-^ -HHHHHHHHHHHHMNHHH Dry. 1.23 1.58 1.41 2.81 1.57 1.17 1.13 1.49 1.31 1.62 1.72 2.28 2.01 2.47 2.70 1.84 2.37 2.63 4.19 2.99 1.73 1.99 2.52 As fired. 8S$£222S88gSSg£S;S §833888 ^^^eorH-^HJrt^NcideoMNNNci^eorH-cqw Per indicated horse- power developed. Com- bus- tible. 83gS3S888S5£283kS&2§g;S8SSg OHHHH * • • ‘.J^iH.HrHrHrH.HeirHrH.-irH Dry. HHHNHH ,HrHiH,HiH,HCsicHoics Location of mine or deposit. Marianna, Pa do Madison, Pa Elizabeth City, N. C Madison, Pa Pocahontas, Va do do do Rockdale, Tex Lytle, Tex Walston, Pa Lehigh, N. Dak lone, Cal Walston, Pa Scranton, N. Dak lone, Cal Sherrard, 111 Auburn, R. I do Coalville, U tah Tono, Wash Portsmouth, R. I Designation of fuel. § Ji d 3 S3 d a d d 2 2 2 $ 8 s' 5 o' o* « oa 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 -g fc fc 53 5 £ 5 fc fc £ fc % £ fc £ £ & £ £ fc fc & fc £ S Test No. g5SSSSgSSS|HS3|gg||s|85 56 RHODE ISLAND COAL. In general, a study of the full tables as published in Bulletin 13 of the Bureau of Mines shows that it requires from 1 to 2 pounds of Pocahontas coal or bituminous coal from central Pennsylvania to produce 1 available electric horsepower-hour as compared with 2.85 to 5.29 pounds of Rhode Island coal. This may be stated differ- ently as follows: One ton of Pocahontas coal or central Pennsylvania bituminous coal will yield 1,000 to 2,000 available horsepower-hours, whereas Rhode Island coal, according to the tests made, will yield from 375 to 700 horsepower-hours. Generally, the yield from Rhode Island coal appears to have been about one-third of that from the other coals named. If account be taken of the cost and interest for transmission lines from the field to centers of distribution, as from Portsmouth to Providence, and the added cost of handling the larger quantity of coal necessary and the very much larger quantity of ash, it appears that Rhode Island coal at the mouth of the mine for use in the producer-gas plant, is worth only one-fourth to one-third the value of competing coals delivered at Providence or Boston. If it be assumed, however, that specially designed apparatus would prevent the loss of gas noted in the experiments it seems possible that from 2 to 3 pounds of Rhode Island coal could be made to produce 1 electric horsepower-hour, averaging say 2J pounds, against an aver- age of, say, li pounds for competing steam coals. With the added costs referred to above, it seems that a ton of average selected Rhode Island coal should deliver in Providence or Boston electric power equivalent to that obtained from one-half ton of average competing coals. In November, 1913, Pocahontas coal was selling at wholesale in Providence and Boston at a little under $4 a ton. In order to com- pete with power produced by that coal, Rhode Island coal of the best grade must be mined and delivered at the mouth of the mine to a producer-gas plant for not over half that price, or $2 a ton. In using Rhode Island coal in the producer-gas plant, the cost of mining might be reduced sufficiently to allow competition by put- ting the producer-gas plant in the mine, as low in the basin as pos- sible. As the coal carries no combustible volatile matter, neither the coal nor the dust should offer any danger of fire or explosion and, as the rocks adjacent to the coal are very firm, the cost of preparing rooms should be little more than the cost of excavation. Such rooms are now used for pumps in the Portsmouth mine. By plac- ing the plant low the coal can be lowered by gravity from the higher levels. The plant could also be installed in small movable units, including a gas producer and gas engine, the power to be taken out of the mine as electricity. By this method it might prove feasible to move the unit plants from one of these large lenses to another. As these lenses in the Portsmouth mine and at Cranston appear to CONCLUSIONS. 57 have, in places, a length of 1,000 feet or more and a width of 100 or 200 feet or more and, at Portsmouth, an average thickness of 4J feet, it seems that one of them should yield sufficient tonnage to cover the cost of moving and installation of a small unit. Whether such a mine installation, by eliminating the cost of the lift out of the mine, would reduce the total cost sufficiently to render competition possible would have to be demonstrated. USE FOR FOUNDRY FACINGS AND FURNACE LININGS. In the preceding sections the utilization of Rhode Island anthra- cite has been discussed. This has been the specific purpose of this bulletin. A little may, however, be said in regard to the use of the more graphitic portions of the beds. Though all the anthracite con- tains more or less graphite, portions of the beds have been changed entirely to what appears to be graphite. Such a bed at Fenners Ledge is being mined at present in an open cut by Mr. Fenner and sold for foundry facings, for which it appears to be well adapted after the proper preparation. At the old Gross mine, to the south, an attempt was made to prepare the graphite for market. Buildings were erected and machinery installed. The graphite was crushed and screened, using expensive brass sieves. The process adopted did not prove successful, apparently owing to the difficulty of separating the fine quartz. Graphite has also been mined at Bridgeton, Valley Falls, and Tiverton, at the first and last places from open cuts, but at Valley Falls the workings were extended underground. The material was used for foundry facings and some of it for furnace linings. CONCLUSIONS. A review of the physical and chemical character of Rhode Island coal, the history of its past exploitation and use, and past and recent tests of its use leads to the following general conclusions: Rhode Island coal is a high-ash, high-moisture, graphitic anthra- cite coal of high specific gravity. Calorimeter tests show it to yield from 6,000 to 11,000 British thermal units, averaging, as taken from the mine, about 9,000 Brit- ish thermal units, or about 10,000 after air drying. As compared with coals shipped to New England, with which it must compete, which range from 12,000 British thermal units for Pennsyl- vania anthracite culm to nearly 15,000 British thermal units, and average 13,000 for anthracite and about 14,500 for bituminous as mined, Rhode "Island coal yields on the average from 60 to 70 per cent of the heat value of these competing coals. The best of the Rhode Island coal may reach 90 per cent of the heat value of the poorest competing coal and 80 per cent of the better grade. 58 RHODE TSLAND COAL. A careful test in actual practice showed Rhode Island coal to have 72 percent of the efficiency of Lackawanna coal. In experimental tests by the Bureau of Mines, Rhode Island coal yielded from 54 to 68 per cent as much horsepower as the other coals listed and from 48 to 60 per cent as many pounds of water evaporated per pound of fuel. In household and steam use it is found to ignite slowly and with difficulty and to make so hot a fire as to destroy stove tops, melt vessels and boilers placed on it, and destroy furnace linings, so that the fire is difficult to maintain and control. Its ignition and burning are improved by breaking down to small sizes and careful screening. Rhode Island coal has been successfully used in the metallurgy of copper and iron. Evidence is lacking to show that it could compete with coke in the modern furnace. Rhode Island coal has been briquetted, but without commercial success. It is believed that future tests may make possible the pro- duction of briquets that hold together and do not smoke. The high specific gravity renders washing o»f this coal with present methods difficult if not impossible. In producer-gas tests by the Bureau of Mines, Rhode Island coal yielded from 375 to 700 horsepower-hours per ton of coal, as compared with 1,000 to 2,000 available horsepower-hours for competing coals. Specially designed plants, it seems reasonable to suppose, might be made to yield at least one-half as much power with Rhode Island coal as with competing coals. In general, it appears that at the present time the best outlook for Rhode Island coal is in the production of electric power at the mines, either in steam engines or by means of specially devised producer-gas or water-gas plants. It appears further, however, that this can not be done with financial success until it can be shown that Rhode Island coal can be mined and delivered at the fur- nace for less than one-half the wholesale price of competing coals in Providence and Boston. PAPERS AND REPORTS. Papers and reports to which reference is made or which are of value in connection with this subject are listed below in chronologic order: 1. Providence Journal. Through the kindness of officials of the Providence Public Library, the writer had access to the old files of the Journal and to a large number of clippings on the subject of Rhode Island coal. These have formed the basis of much of the section on the history of development (pp. 7-14). 2. Hearing on the memorial of the New England Coal Mining Co. before the select special committee of the General Assembly of Rhode Island and Providence Plantations, together with the report of the committee, 1838. 3. Report and bill to the Commonwealth of Massachusetts relating to the coal mines of the State, 1839. PAPERS AND REPORTS. 59 4. Jackson, C. T., Report on the geologic and agricultural survey of the State of Rhode Island, Providence, 1840. 5. Hitchcock, E. T., Final report on the geology of Massachusetts, Northampton, 1841. 6. Mount Hope Coal Co., The coal beds of Rhode Island, 1852. 7. Hitchcock, E. T., The coal field of Bristol County and of Rhode Island: Am. Jour. Sci., 2d ser., vol. 16, pp. 227-336, 1853. 8. Hitchcock, E. T., Geology of the Island of Aquidneck: Proc. Am. Assoc. Adv. Sci., vol. 14, pp. 112-137, 1860. 9. Rhode Island Society for the Encouragement of Domestic Industry, Providence, 1869. 10. Memorial of T. S. Ridgway, in relation to the coal field of Rhode Island, pre- sented to the General Assembly, 1870. 11. Emmons, A. B., Notes on the Rhode Island and Massachusetts coals: Am. Inst. Min. Eng. Trans., vol. 13, pp. 510-517, 1885. 12. Adams, W. H., Eng. and Min. Jour., 1886. (Referred to as having described some tests on Rhode Island coal; could not be located.) 13. Providence Franklin Society. Report on the geology of Rhode Island, Provi- dence, 1887. (Gives a complete list of papers on the geology of Rhode Island up to the time of publication.) 14. Shaler, N. S., Woodworth, J. B., Foerste, A. F., Geology of the Narragansett Basin: U. S. Geol. Survey Mon. 33, 1899. (This is a complete comprehensive report on the geology of the coal basin containing the Rhode Island coal. It does not deal at great length with the coal from either the stratigraphic or the commercial standpoint.) 15. Second Geol. Survey Pennsylvania Summary Rept., vol. 3, pt. 1, 1895. 16. Lord, N. W., Experimental work conducted in the chemical laboratory of the United States fuel-testing plant at St. Louis, Mo.: U. S. Geol. Survey Bull. 323, 1907. 17. Breckenridge, L. P., A study of four hundred steaming tests, made at the fuel- testing plant, St. Louis, Mo.: U. S. Geol. Survey Bull. 325, 1907. 18. Holmes, J. A., in charge, Report of the United States fuel-testing plant at St. Louis, Mo.: U. S. Geol. Survey Bull. 332, 1908. 19. Bin-rows, J. S., Mine sampling and chemical analyses of coals tested at the United States fuel-testing plant, Norfolk, Va.: U. S. Geol. Survey Bull. 362, 1908. 20. Randall, D. T., Tests of coal and briquets as fuel for house-heating boilers: U. S. Geol. Survey Bull. 366, 1908. 21. Snodgrass, J. M., Fuel tests of house-heating boilers: University of Illinois Bull. 31, 1909. 22. Preliminary report of the natural resources survey of Rhode Island: Rhode Island Bur. Industrial Statistics Bull. 1 (Ann. Rept. 1909, pt. 3), 1910. 23. Fernald, R. H., and Smith, C. D., Resume of producer-gas investigations: Bur. Mines Bull. 13, 1911. 24. Lord, N. W., and others, Analyses of coal in the United States: Bur. Mines Bull. 22, 1913. Brief references were made in the Engineering and Mining Journal and other journals and papers given in the list published in item 13. INDEX. Analyses of coals used in briquets 47 of Rhode Island anthracite 20-29, 44 Aquidneck Coal Co., operations of 8, 9, 10 Ash, cause of high content of 19 determinations of 21-22 percentage of 23-33 B. Bibliography 58-59 Blackstone Coal Co., operations of 11 Brick burning, possible use of the coal for 48-49 Briquets, attempts to make 13 tests of 40-41,43-45,46-48 Bryant, W. C., cited 39 Budlong mine, anthracite in, diagram show- ing thickness of 19 face of bed north of mouth of slope, plate showing 12 north end of, plate showing 19 open cut in, plate showing 12 operation of 12 surface plant at, plate showing 13 Bureau of Mines, briquetting tests by 46-48 steaming tests of various coals by 45-46 tests of the coal in a producer-gas plant by 49-57 C. Chemical character of the coal 17, 23-33 Clay, test of, desirable 16 Compressed Coal Co., operations of 13 Cranston coal, briquetting tests of 43-45,46-48 mining of 14 producer-gas tests of 50-57 steam test of 42-43 Cranston Coal Co., operations of 12 Cumberland, coal found in 8 D. Drilling, results of 17 Durfee, W. F., interest revived by 11-12 E. Electricity, use of coal for 7 Emmons, A. B., cited 37-38 F. Fenner Ledge , mining at 14 graphite mine at, view in 16 Foundry facings, use of graphite for 57 Furnace linings, use of graphite for 57 G. Gas producer, advantage of placing, in mine. 56-57 Graphite, content of 20 Fenner Ledge, analyses of. 33 produced from coal by heat 18-19 uses of 57 H. Page. Heat value, low, reason for 33-37 Heating power, chart showing 24 comparison of 32 Household use of the coal 39-41 L. Lackawanna coal, ash in 29 comparison of, with Cranston coal 42-43 heating power of 35 Lenses, irregular, formed by pressure 18 Lime burning, possible use of the coal for 48-49 Lotteries granted to aid in mining coal 7, 8 M. Mansfield, Mass., analyses of coals from 29 coal mining at 9 Mansfield Coal Co., operations of : 9 Mansfield Mining Co., operations of 9 Massachusetts Mining Co., operations of 9 Metallurgy, use of the coal in 10, 11, 46 Mining, cost of, conditions affecting 14-17 Mitchell, Thomas, operations of 12 Moisture, behavior of coal toward 32,37-38 percentage of 23-33 Mount Hope Mining Co., operations of 10 N. New England Coal Mining Co., operations of. 8-9 New York Carbon Iron Co., operations of 11 Newport County coals, analyses of 26 Nichols, Purton, mines opened by 7 P. Pennsylvania, analyses of coals from 30 Physical character of the coal 20-21 Pocahontas coal, heating power of 34-35 Pocasset Coal Co., operations of 10 Porter, J. B., and Durley, R. J., cited 22 Portsmouth coal, analyses of 28, 29 behavior of, toward moisture 37-38 producer-gas test of 50-57 Portsmouth Coal Co. of 1847, operations of . . . 9 Portsmouth Coal Co. of 1912, North and South mines of, equipment of 14 operations of 14 South mine of, plate showing surface plant at 13 Pressure, effects of, on the coal 6, 14-15, 17-19 regional differences of 19 Producer gas, tests of the coal for 49-57 Providence County coals, analyses of 27 Providence Waterworks, test of coal at 10-11 Pyrite, content of 20, 21 Q. Quartz, content of 20, 21 Quartz veins, formation of 19 61 62 INDEX, R. Page. Revolutionary War, use of coal during 7 Rhode Island coal, character of 5-6,57-58 compared with other coals when used in a producer-gas plant 55-56 history of 7-9,9-14 proper and improper modes of using 6-7, 10 Rhode Island Coal Co. of 1809, operations of. 8 Rhode Island Coal Co. of 1840, operations of. 9 Rhode Island Coal Co. of 1909, operations of. 13-14 Rhode Island coal field, sketch map of • 6 Roger Williams mine, working of 11 S. Snodgrass, J. M., cited 41 Specific gravity, determinations of 21-22 Standish, Miles, operations of 12 Steam raising, use of the coal in 41-46 T. Page. Taunton Copper Co., operations of 10 use of coal by 5, 10 U. Uses, practicable, of Rhode Island coal 38-39 V. Virginia, analyses of coals from 31 W. Water gas, possible use of the coal for 49 W est Virginia, analyses of coals from 31 Worcester Steel Works, operations of 12 O DEPARTMENT OF THE INTERIOR Franklin K. Lane, Secretary United States Geological Survey George Otis Smith, Director Bulletin 616 THE DATA OF GEOCHEMISTRY THIRD EDITION FRANK WIGGLESWORTH CLARKE WASHINGTON GOVERNMENT PRINTING OFFICE 1916 ' ^ 5T7 2 : Y £> f't-t-'fT bib CONTENTS. Introduction PagG g Chapter I. The chemical elements Nature of the elements ^2 Distribution of the elements 2.3 Relative abundance of the elements 22 The periodic classification g^ Meteorites gg Chapter II. The atmosphere 42 Composition of the atmosphere The relations of carbon dioxide to climate 47 Rainfall * * 4 g The primitive atmosphere 5g Chapter III. Lakes and rivers 5g ori 8 in 58 Statement of analyses ^g The interpretation of analyses Springs " ' . 63 Changes of composition 04 Analyses of river waters gg The St. Lawrence basin gg The Atlantic slope 72 The Mississippi basin Southwestern rivers g 2 Rivers of California gg The Columbia River basin 84 Other northwestern rivers gg The Saskatchewan system 87 Summary for North America gg Rivers of South America g 0 Lakes and rivers of Europe gg Rivers of India and Java 205 The Nile 206 Organic matter in waters 207 Contamination by human agencies ]0g Gains and losses in waters 2 10 Chemical denudation 2H Chapter IV. The ocean 119 Elements in the ocean 219 Composition of oceanic salts 222 Carbonates in sea water 228 Oceanic sediments 230 Potassium and sulphates 238 The chlorine of sea water 239 The dissolved gases 242 Influence of living organisms on the ocean 247 Age of the ocean 4S 3 4 CONTENTS. Chapter V. The waters of closed basins Preliminary statement The Bonneville basin The Lahontan basin Lakes of California Northern lakes Central and South America Caspian Sea and Sea of Aral The Dead Sea Other Russian agad Asiatic lakes Miscellaneous lakes Summary Chapter VI. Mineral wells and springs Definition Classification Chloride waters Sulphate waters Carbonate waters Waters of mixed type Siliceous waters Nitrate, phosphate, and borate waters Acid waters Summary of waters Changes in waters Calcareous sinter Ocherous deposits Siliceous deposits Reactions with adjacent material Yadose and juvenile waters Thermal springs and volcanism Bibliographic note Chapter VII. Saline residues Deposition of salts Concentration of sea water The Stassfurt salts Other salt beds Analyses of salt - . Analyses of gypsum Bitterns Sodium sulphate Miscellaneous desert salts Alkaline carbonates Borates Nitrates The alums Chapter VIII. Volcanic gases and sublimates Gaseous emanations Sublimates Occluded gases Volcanic explosions Summary Page. 154 154 154 157 160 161 164 165 167 169 172 173 179 179 180 181 187 190 193 194 196 198 201 202 203 204 205 209 213 214 215 217 217 218 221 228 230 232 232 233 236 237 243 253 259 260 260 269 274 285 289 CONTENTS. 5 Page. Chapter IX. The molten magma 291 Temperature 291 Influence of water 297 Magmatic solutions 298 Eutectics i 301 Separation of minerals 304 Differentiation 307 Radioactivity 313 Chapter X. Rock-forming minerals 321 Preliminary statement 321 Diamond and graphite 322 Native metals 328 Sulphides 332 Fluorides 335 Corundum 336 The spinels 341 Hematite 346 Titanium minerals 348 Cassiterite and zircon 352 Phosphates 354 The silica minerals 356 The feldspars 363 Leucite and analcite 368 The nephelite group 371 The cancrinite-sodalite group 373 The pyroxenes : 376 The amphiboles 383 The olivine group 389 The micas 391 The chlorites 396 The melilite group 398 The garnets 400 Yesuvianite 403 The scapolites 403 Iolite 405 The zoisite group 406 Topaz 408 The andalusite group 409 Staurolite 411 Lawsonite 411 Dumortierite 412 Tourmaline 412 Beryl 413 Serpentine, talc, and kaolinite 414 The zeolites 416 The carbonates 417 Chapter XI. Igneous rocks 419 Preliminary considerations 419 Classification 420 Composition of rocks 433 The rhyolite-granite group 433 The trachyte-syenite group! 438 6 CONTENTS. Chapter XI. Igneous rocks — Continued. Composition of rocks — Continued. Page. Nephelite rocks 443 Leucite rocks 447 Analcite rocks 449 The monzonite group 451 The andesite-diorite series 453 The basalts 457 Diabase 460 The gabbros 462 Femic rocks 463 Basic rocks 466 Limiting conditions 469 Proximate calculations 473 Chapter XII. The decomposition of rocks 476 The general process 476 Solubility of minerals 478 Effects of vegetation 483 Influence of bacteria 485 Influence of animal life 485 Products of decomposition 486 Rate of decomposition 490 Kaolin 491 Laterite and bauxite 493 Absorption 501 Sand 502 Silt 504 Glacial and residual clays 507 Loess 509 Marine sediments 511 Glauconite 516 Phosphate rock 519 Ferric hydroxides 528 Manganese ores 533 Chapter XIII. Sedimentary and detrital rocks 537 Sandstones 537 Flint and chert 542 Shale and slate 545 Limestone 548 Dolomite .- 559 Iron carbonate 571 Silicated iron ores 573 Gypsum 576 Native sulphur 576 Celestite 578 Barite 579 Fluorite 582 Chapter XI Y. Metamorphic rocks 583 Metamorphic processes 583 Classification 588 Uralitization 589 Glaucophane schists 591 Sericitization 593 CONTENTS. 7 Chapter XIV. Metamorphic rocks — Continued. Page. Other alterations of feldspar 594 Chloritization 600 Constitutional formulas 600 Talc and serpentine 602 Quartzite 606 Metamorphosed shales 608 Ferruginous schists 609 Dehydration of clays 610 Mica schist 614 Gneiss 618 Metamorphic limestones 620 Diagnostic criteria 624 Chapter XV. Metallic ores 626 Definition 626 Source of metals 627 Gold 641 Silver 648 Copper 655 Mercury 664 Zinc and cadmium 669 Lead 676 Tin 683 Arsenic, antimony, and bismuth 687 Nickel and cobalt 691 Chromium 696 Molybdenum and tungsten 698 The platinum metals 700 Vanadium and uranium 705 Columbium, tantalum, and the rare earths 710 Chapter XVI. The natural hydrocarbons 713 Composition 713 Syntheses of petroleum 722 Origin of petroleum 726 Chapter XVII. Coal 738 Origin of coal 738 Peat 742 Lignite 745 Bituminous coal 750 Anthracite 752 The variations of coal 755 The gases in coal 757 Artificial coals 760 The constitution of coal 763 Index 767 THE DATA OF GEOCHEMISTRY . 1 By F. W. Clarke. INTRODUCTION. In the crust of the earth, with its liquid and gaseous envelopes, the ocean and the atmosphere, about eighty chemical elements are now recognized. These elements, the primary units of chemical analysis, are widely different as regards frequency; some are extremely rare, others are exceedingly abundant. A few occur in nature uncombined ; but most of them are found only in combination. The compounds thus generated, the secondary units of geochemistry, are known as mineral species; and of these, excluding substances of organic origin, only about a thousand have yet been identified. By artificial means innumerable compounds can be formed; but in the chemistry of the earth’s crust the range of possibility seems to be extremely limited. From time to time new elements and new mineral species are discovered; but it is highly probable that all of them which have any large importance in the economy of nature are already known. The rarest substances, however, whether elementary or compound, supply data for the solution of chemical problems; they can not, therefore, be ignored or set to one side as having no significance. In scientific investigation aU evidence is of value. By the aggregation of mineral species into large masses rocks are produced; and these are the fundamental units of geology. Some rocks, such as quartzite or limestone, consist of one mineral only, more or less impure; but most rocks are mixtures of species, in which, either by the microscope or by the naked eye, the individual compo- nents can be clearly distinguished. Being mixtures, rocks are widely variable in composition; and yet certain types are of common occur- rence, whHe others are small in quantity and rare. The commonest rock-forming minerals are naturally the more stable compounds of the most abundant elements ; and the rocks themselves represent the outcome of relatively simple rather than of complex reactions. Sim- plicity of constitution seems to be the prevaHing rule. An eruptive 1 The first edition of this volume was published in 1908 as Bulletin 330 of the United States Geological Survey. A second edition appeared in 1911 as Bulletin 491. The work has been revised and enlarged for the present edition. 9 10 THE DATA OF GEOCHEMISTRY. rock, for example, may be composed mainly of eight chemical ele- ments, namely, oxygen, silicon, aluminum, iron, calcium, magnesium, sodium, and potassium. These elements are capable of combining so as to form some hundreds of mineral species ; and yet only a few of the latter appear in the rock mass. The less stable species rarely occur; the more stable always predominate. The reactions which took place during the formation of the rock were strivings toward chemical equilibrium, and a maximum of stability under the existing condi- tions was the necessary result. The rarer rocks, like many of the rarer minerals, are the products of exceptional conditions; but the tendency toward stable equilibrium is always the same. Each rock may be regarded, for present purposes, as a chemical system, in which, by various agencies, chemical changes can be brought about. Every such change implies a disturbance of equilibrium, with the ultimate formation of a new system, which, under the new conditions, is itself stable in turn. The study of these changes is the province of geochemistry. To determine what changes are possible, how and when they occur, to observe the phenomena which attend them, and to note their final results are the functions of the geochemist. Analy- sis and synthesis are his two chief instruments of research, but they become effective only when guided by a broad knowledge of chemical principles, which correlate the data obtained and extract from the evidence its full meaning. From a geological point of view the solid crust of the earth is the main object of study; and the reactions which take place in it may be conveniently classified under three heads — first, reactions between the essential constituents of the crust itself; second, reactions due to its aqueous envelope; and third, reactions produced by the agency of the atmosphere. That the three classes of reactions shade into one another, that they are not sharply defined, must be admitted ; but the distinction between them is valid enough to serve a good purpose in the arrangement and discussion of the data. Under the first heading the reactions which occur in volcanic magmas and during their contact with rock masses are studied • under the second we find the changes due to percolating waters and the chemistry of natural waters in general; the essentially surficial action of the atmosphere forms the subject matter of the third. Furthermore, for convenience of study, the solid crust of the earth may be regarded as made up of three shells or layers, which inter- penetrate one another to some extent, but which are, nevertheless, definite enough to consider separately. First and innermost there is a shell of crystalline or plutonic rocks, of unknown thickness, which forms the nearest approach to the original material of which the crust was composed. Next, overlying this layer, is a shell of sedimentary and fragmental rocks; and above this is the third layer of soils, clays, gravels, and the like unconsolidated material. The INTRODUCTION. 11 second and third shells are relatively thin, and consist of material derived chiefly from the first, in great part through the transforming agency of waters and of the atmosphere, although organic life has had some share in bringing about certain of the changes. In addi- tion to the substances which the two derived layers have received from the original plutonic mass they contain carbon and oxygen taken up from the atmosphere, and also a considerable proportion of water which has become fixed in the clays and shales. Along with this gain of material, there has been a loss of salts leached out into the ocean, but the factor of increase is the larger. When igneous rocks are transformed into sedimentary rocks, there is an average net gain of weight of 8 or 9 per cent, as roughly estimated from the composition of the various kinds of rock under consideration. To some extent, then, the ocean and the atmosphere are being slowly absorbed by and fixed in the solid crust of the earth; although under certain condi- tions this tendency is reversed, with liberation of water and of gases. A perfect balance of this sort, however, can not be assumed; and how far the main absorptive process may go, it is hardly worth while to conjecture. The data available for the solution of the problem are too uncertain. Upon the subject of geochemistry a vast literature exists, hut it is widely scattered and portions of it are difficult of access. The general treatises, like the classical works of Bischof and of Roth, are not recent, and great masses of modern data are as yet uncor- related. The American material alone is singularly rich, but most of it has been accumulated since Roth’s treatise was published. The science of chemistry, moreover, has undergone great changes during the last 25 years, and many subjects now appear under new and generally unfamiliar aspects. The methods and principles of physical chemistry are being more and more applied to the solution of geochemical problems, 1 as is shown by the well-known researches of Van’t Hoff upon the Stassfurt salts and the magmatic studies of Vogt, Doelter, and others. The great work in progress at the geo- physical laboratory of the Carnegie Institution is another illustration of the change now taking place in geochemical investigation. To bring some of the data together, to formulate a few of the problems, and to present certain general conclusions in their modern form are the purposes of this memoir. It is not an exhaustive monograph upon geochemistry, but rather a critical summary of what is now known and a guide to the more important literature of the subject. If it does no more than to make existing data available to the reader, its preparation will be justified. 1 Principles of chemical geology, by J. V. Elsden (London, 1910), is an excellent though brief treatise on this aspect of geochemistry. It covers, however, only a small portion of the field. CHAPTER I. THE CHEMICAL ELEMENTS. NATURE OF THE ELEMENTS. Although many thousands of compounds are known to chemists, and an almost infinite number are possible, they reduce on analysis to a small group of substances which are called elements. It is not necessary for the geologist to speculate on the ultimate nature of these bodies; it is enough for him to recognize the fact that all the compounds found in the -earth are formed by their union with one another and that they are not to any considerable extent reducible to simpler forms of matter by any means now within our control. To the geochemist, generally speaking, they are the final results of analysis, beyond which it is rarely necessary to go. This statement, however, must not be taken without qualification. It is probable, as shown by the writer many years ago , 1 that the elements were originally developed by a process of evolution from much simpler forms of matter, as is indicated by the progressive chemical com- plexity observed in passing from the nebulae through the hotter stars to the cold planets. Changes in the opposite direction have been discovered through recent investigations upon radioactivity , 2 by which an actual breaking down of some elements is proved. Uranium undergoes a slow metamorphosis to radium, and radium in turn passes through a series of changes which ends in the produc- tion of helium. Thorium also exhibits a similar instability, but thoiium, radium, and uranium are elements of high atomic weight, and therefore, in all probability, of maximum complexity. It is conceivable that all the elements may be similarly unstable, but in so slight a degree that their transmutations have not yet been detected. Speculations of this order, however, can be left out of consideration now. For present purposes the recognized elements are our fundamental chemical units, and the questions of their origin and transmutability may be neglected. At present the elements enumerated in the subjoined table are known, all doubtful substances being omitted. The radio activ^le- ments, polonium, actinium, radio thorium, ionium, etc., are also dis- 1 F. W. Clarke, Pop. Sci. Monthly, January, 1873. See also the later well-known speculations of J. Nor- man Lockyer. 2 This subject will be discussed at length later. 12 THE CHEMICAL ELEMENTS. 13 regarded for the reasons that they are imperfectly known and geologically unimportant. The recently discovered celtium is also too little known to be included here. The chemical elements. Symbol. Atomic weight. Aluminum A1 27. 1 Antimony Sb 120.2 Argon A 39. 88 Arsenic As 74. 96 Barium Ba 137. 37 Bismuth Bi 208.0 Boron t . B 11.0 Bromine Br 79. 92 Cadmium Cd 112. 40 Caesium Cs 132. 81 Calcium Ca 40. 09 Carbon C 12. 005 Cerium Ce 140. 25 Chlorine Cl 35. 46 Chromium Cr 52.0 Cobalt Co 58. 97 Columbium Cb 93.5 Copper Cu 63. 57 Dysprosium Dy 162.5 Erbium Er 167.4 Europium Eu 152.0 Fluorine F 19.0 Gadolinium Gd 157.3 Gallium Ga 69.9 Germanium Ge 72.5 Glucinum G1 9.1 Gold Au 197.2 Helium He 4. 00 Hydrogen H 1. 008 Indium In 114.8 Iodine I 126. 92 Iridium Ir 193. 1 Iron Fe 55. 85 Krypton Kr 82.9 Lanthanum La 139.0 Lead Pb 207. 20 Lithium Li 6.94 Lutecium Lu 175.0 Magnesium Mg 24. 32 Manganese Mn 54. 93 Mercury Hg 200. 6 Molybdenum Mo 96.0 Symbol. Atomic weight. Neodymium Nd 144.3 Neon Ne 20.0 Nickel Ni 58. 68 Niton Nt 222.4 Nitrogen N 14. 01 Osmium Os 190. 9 Oxygen O 16. 00 Palladium Pd 106. 7 Phosphorus P 31. 04 Platinum Pt 195.2 Potassium K 39. 10 Praseodymium Pr 140.9 Radium Ra 226. 0 Rhodium Rh 102.9 Rubidium Rb 85. 45 Ruthenium Ru 101.7 Samarium Sa 150.4 Scandium Sc 44. 1 Selenium Se 79.2 Silicon Si 28.3 Silver Ag 107. 88 Sodium Na 23. 00 Strontium Sr 87. 63 Sulphur S 32. 06 Tantalum Ta 181.5 Tellurium Te 127.5 Terbium Tb 159.2 Thallium T1 204.0 Thorium Th 232.4 Thulium Tm 168.5 Tin Sn 118.7 Titanium Ti 48. 1 Tungsten W 184.0 Uranium U 238.2 Vanadium V 51. 06 Xenon Xe 130.2 Ytterbium (Neoyt- terbium) Yb 173.5 Yttrium Yt 88.7 Zinc Zn 65. 37 Zirconium Zr 90.6 DISTRIBUTION OF THE ELEMENTS . 1 The elements differ widely in their abundance and in their mode of distribution in nature. Under the latter heading the more important data may be summarized as follows: Aluminum . — The most abundant of all the metals. An essential constituent of all important rocks except the sandstones and lime- 1 For an early table showing distribution, see Elie de Beaumont, Bull. Soc. g£ol. France, 2d ser., vol. 4, 1846-47, p. 1333. 14 THE DATA OF GEOCHEMISTRY. stones, and even in these its compounds are common impurities. Being easily oxidized, it nowhere occurs native. Found chiefly in silicates, such as the feldspars, micas, clays, etc.; but also as the oxide, corundum; the hydroxide, bauxite; as fluoride in cryolite; and in various phosphates and sulphates. With the exception of the fluorides, only oxidized compounds of aluminum are known to exist in nature. Antimony. — Common, but neither abundant nor widely diffused. Found native, more frequently as the sulphide, stibnite, also in vari- ous antimonides and sulphantimonides of the heavy metals, and as oxide of secondary origin. The minerals of antimony are generally found in metalliferous veins, but the amorphous sulphide has been observed as a deposit upon sinter at Steamboat Springs, Nevada. Argon . — An inert gas that forms nearly 1 per cent of the atmos- phere, and is also found in some mineral springs. No compounds of argon are known. Arsenic . — Found native, in two sulphides, in various arsenides and sulpharsenides of the heavy metals, as oxide, and in a considerable number of arsenates. Axsenopyrite is the commonest arsenical min- eral. Arsenic is very widely diffused and traces of it exist normally even in organic matter. It is not an uncommon ingredient in min- eral, especially thermal, springs. In its chemical relations it is regarded as nonmetallic and closely allied to phosphorus. Barium . — Widely distributed in small quantities throughout the igneous rocks, probably as a minor constituent of the feldspars and micas, although other silicates containing barium are known. Com- monly found concentrated as the sulphate, barite, or as the carbonate, witherite. This element occurs only in oxidized compounds. 1 Bismuth . — Resembles antimony in its modes of occurrence, but is less common. Native bismuth and the sulphide, bismuthinite, are its chief ores. Two silicates of bismuth, several sulphobismuthides, and the telluride, oxide, carbonate, vanadate, and arsenate exist as rela- tively rare mineral species. Boron. — An essential constituent of several silicates, notably of tourmaline and datolite. Its compounds are obtained commercially from borates, such as borax, ulexite, and colemanite, or from native orthoboric acid, sassolite, which is foimd in the waters of certain volcanic springs. Some alkaline lakes or lagoons, especially in Cali- fornia and Tibet, yield borax in large quantities. Bromine . — Found in natural waters in the form of bromides. Sea water contains it in appreciable quantities, and much bromine has been extracted from the brine wells of West Virginia and Michigan. The bromide and chlorobromide of silver are well-known ores. 1 On barium in soils, see G. H. Failyer, Bull. Bur. Soils No. 72, U. S. Dept Agr., 1910. THE CHEMICAL ELEMENTS. 15 Cadmium . — A relatively rare metal found in association with zinc, which it resembles. Occurs usually as the sulphide, greenockite. Cxsium . — A rare metal of the alkaline group, allied to potassium. Often found in lepidolite, and in the waters of some mineral springs. The very rare mineral pollucite is a silicate of aluminum and caesium. Calcium . — One of the most abundant metals, but never found in nature uncombined. An essential constituent of many rock-forming minerals, especially of anorthite, garnet, epidote, the amphiboles, the pyroxenes, and scapolite. Limestone is the carbonate, fluorspar is the fluoride, and gypsum is the sulphate of calcium. Apatite is the fluophosphate or chlorophosphate of this metal. Many other mineral species also contain calcium, and it is found in nearly all natural waters and in connection with organized life, as in bones and shells. Calcium sulphide has been identified in meteorites. Carbon . — The characteristic element of organic matter. In the mineral kingdom carbon is found crystallized as graphite and dia- mond and also amorphous in coal. Carbon dioxide is a normal constituent of atmospheric air. Natural gas, petroleum, and bitumen are essentially hydrocarbons. Carbonic acid and carbonates exist in most natural waters, and great rock masses are composed of carbon- ates of calcium, magnesium, and iron. A few silicates contain car- bon, but of these, cancrinite is the only species having petrographic importance. Cerium . — One of the group of elements known as the metals of the rare earths. These substances are generally found in granites or elseolite syenites, or in gravels derived therefrom. Cerium exists in a considerable number of mineral species, but the phosphate, monazite, and the silicates, cerite and allanite, are all that need be mentioned here. Chlorine . — The most abundant element of the halogen group. Commonly found as sodium chloride, as in sea water and rock salt. Also in certain rock-forming minerals, such as sodalite and the scapolites, and in a variety of other minerals of greater or less im- portance. Silver chloride, for example, is a well-known ore, and carnallite is valuable for the potassium which it contains. Chromium . — Very widely diffused, generally in the form of chro- mite, and most commonly in magnesian rocks. A few chromates and several silicates containing chromium are also known, but as rela- tively rare minerals. Cobalt . — Less abundant than nickel, with which it is generally associated. Usually found as sulphide or arsenide, or in oxidized salts derived from those compounds. Columbium . 1 — A rare acid-forming element resembling and associ- ated with tantalum. Both form salts with iron, manganese, calcium, Also known as "niobium.” The name columbium has more than 40 years’ priority. 16 THE DATA OF GEOCHEMISTRY. uranium, and the rare-earth metals, the minerals columbite, tantalite, and samarskite being typical examples. All these minerals are most abundant in pegmatite veins. Copper.— Minute traces of this metal are often detected in igneous rocks, although they are rarely determined quantitatively. Also present in sea water in very small amounts. Its chief ores are native copper, several sulphides, two oxides, and two carbonates. The arsenides, arsenates, antimonides, phosphates, sulphates, and silicates also exist in nature, but are less important. In chalco- pyrite and bornite, copper is associated with iron. Dysprosium. — A little-known metal of the rare earths. Erbium. — One of the rare-earth metals of the yttrium group. See “ Yttrium.’ ’ Europium. — Another metal of the rare earths, of slight importance. Fluorine. — The most characteristic minerals of fluorine are cal- cium fluoride (fluor spar) and cryolite, a fluoride of aluminum and sodium. Apatite is a phosphate containing fluorine, and the element is also found in a goodly number of silicates, such as topaz, tourma- line, the micas, etc. Fluorine, therefore, is commonly present in igneous rocks, although in small quantities. Gadolinium. — One of the metals of the rare earths. See “Cerium” and “Yttrium ” Gallium. — A very rare metal whose salts resemble those of alu- minum. Found in traces in many zinc blendes. Always present in spectroscopic traces in bauxite and in nearly all aluminous minerals. Germanium. — A very rare metal allied to tin. The mineral argy- rodite is a sulphide of germanium and silver. Glucinum. — A relatively rare metal, first discovered in beryl, from which the alternative name beryllium is derived. Found also in the aluminate, chrysoberyl; in several rare silicates and phosphates; and in a borate, hambergite. As a rule the minerals of glucinum occur in granitic rocks. Gold. — Found in nature as the free metal and in tellurides. Very widely distributed and under a great variety of conditions, but almost invariably associated with quartz or pyrite. Gold has been observed in process of deposition, probably from solution in alkaline sulphides, at Steamboat Springs, Nevada. It is also present, in very small traces, in sea water. Helium. — An inert gas obtained from uraninite. The largest quantities are derived from the Ceylonese thorianite and the highly crystalline uraninite found in pegmatite. The massive mineral from metalliferous veins contains little or no helium. Traces of helium also exist in the atmosphere, in spring waters, and in some samples of natural gas. THE CHEMICAL ELEMENTS. 17 Holmium . — One of the rare-earth metals. Little known. Hydrogen . — This element forms about one-ninth part by weight of water, and therefore it occurs almost everywhere in nature. In a majority of all mineral species, and therefore in practically all rocks, it is found, either as occluded moisture, as water of crystal- lization, or combined as hydroxyl. All organic matter contains hydrogen, and hence it is an essential constituent of such derived substances as natural gas, petroleum, asphaltum, and coal. The free gas has been detected in the atmosphere, but in very minute quantities. Indium . — A rare metal, found in very small quantities in certain zinc blendes. Spectroscopic traces of it can be detected in many minerals, especially in iron ores. Iodine .— The least abundant element of the halogen group. Found in sea water, in certain mineral springs, and in a few rare minerals ; especially the iodides of silver, copper, and lead. Calcium iodate, lautarite, exists in the Chilean nitrate beds. Iridium . — A metal of the platinum group. See “Platinum.” Iron . — Next to aluminum, the most abundant metal, although native iron is rare. Found in greater or less amount in practically all rocks, especially in those which contain amphiboles, pyroxenes, micas, or olivine. Magnetite and hematite are oxides of iron, limon- ite is a hydroxide, pyrite and marcasite are sulphides, siderite is the carbonate, and there are also many silicates, phosphates, arse- nates, etc., which contain this element. The mineral species of which iron is a normal constituent are numbered by hundreds. Krypton . — An inert gas of the argon group, found in small quanti- ties in the atmosphere. Lanthanum . — A metal of the rare-earth group, almost invariably associated with cerium, g. v. Lanthanite is the carbonate of lanthanum. Lead . — Found chiefly in the sulphide, galena, from which, by alteration, various oxides, the sulphate, and the carbonate are derived. Native lead is rare. A number of sulphosalts are known, several silicates, and also a phosphate, an arsenate, and some vanadates. Galena is frequently associated with pyrite, marcasite, and sphalerite. Lithium . — One of the alkaline metals. Traces of it are found in nearly all igneous rocks, and in the waters of many mineral springs. The more important lithia minerals are lepidolite, spodumene, petal- ite, amblygonite, triphylite, and the lithia tourmalines. Lutecium . — One of the rare-earth minerals. See “Yttrium and ytterbium.” Magnesium . — One of the most abundant metals. In igneous rocks it is represented by amphiboles, pyroxenes, micas, and olivine. Talc, 97270°— Bull. 616—16 2 18 THE DATA OF GEOCHEMISTRY. chlorite, and serpentine are common magnesium silicates, and dolomite, the carbonate of magnesia and lime, is also found in enormous quantities. Magnesium compounds occur in sea water and in many mineral springs. The metal is not found native. Manganese. — Widely diffused in small quantities. Found in most rocks and in some mineral waters. Never native. Occurs commonly in silicates, oxides, and carbonates, less frequently in sulphides, phosphates, tungstates, columbates, etc. The dioxide, pyrolusite, and the hydroxide, psilomelane, are the commonest manganese minerals. Mercury. — This metal is neither abundant nor widely diffused. Exists as native mercury, but is usually found, locally concentrated, in the form of the sulphide, cinnabar. Chlorides of mercury, the oxide, the selenide, and the telluride, are relatively rare minerals. Cinnabar has been observed in process of deposition by solfataric action at Sulphur Bank, California; and Steamboat Springs, Nevada. Molybdenum. — One of the rarer metals. Most frequently found in granite in the form of the sulphide, molybdenite. The molybdates of iron, calcium, and lead are also known as mineral species. Neodymium. — One of the rare-earth metals associated with cerium. Neon. — An inert gas of the argon group, found in minute traces in the atmosphere. Nickel. — Closely allied to cobalt. Found native, alloyed with iron, in meteorites and in the terrestrial minerals awaruite and josephinite. Very frequently detected in igneous rocks, probably as a constituent of olivine. Occurs primarily in silicates, sulphides, arsenides, antimonides, and as telluride, and secondarily in several other minerals. The presence of nickel is especially characteristic of magnesian igneous rocks, and it is generally associated in them with chromium. Niton. — The gaseous emanation of radium. It is the highest member of the argon group. Nitrogen. — The predominant element of the atmosphere, in which it is uncombined. Also abundant in organic matter, and in such derived substances as coal. Nitrates are found in the soil and in cave earth; and in some arid regions, as in Chile, they exist in enormous quantities. Some volcanic waters contain nitrogen in the form of ammonium compounds. Osmium. — A metal of the platinum group. See “Platinum.” Oxygen. — The most abundant of the elements, forming about one- half of all known terrestrial matter. In the free state it constitutes about one-fifth of the atmosphere; and in water it is the chief ele- ment of the ocean. All important rocks contain oxygen in propor- tions ranging from 45 to 53 per cent. Palladium. — A metal of the platinum group. THE CHEMICAL ELEMENTS. 19 Phosphorus. — Found in nearly all igneous rocks, generally as a constituent of apatite. With one or two minor exceptions, it exists in the mineral kingdom only in the form of phosphates, of which a large number are known. An iron phosphide occurs in meteorites. Phosphorus is also an essential constituent of living matter, espe- cially of bones, and certain large deposits of calcium phosphate are of organic origin. Platinum. — Platinum, iridium, osmium, ruthenium, rhodium, and palladium constitute a group of metals of which the first named is the most important. As a rule they are found associated together, and generally uncombined. To the latter statement there are two known exceptions — sperrylite is platinum arsenide, and laurite is ruthenium sulphide. Native platinum, platiniridium, iridosmine, and native palladium are all reckoned as definite mineral species. The metals of this group are commonly found associated with magnesian rocks, or in gravels derived from them. Chromite often accompanies platinum, and so also do the ores of nickel. Sperrylite is found in the nickeliferous deposits at Sudbury, Canada; and has also been identified in the sulphide ores of the Rambler mine in Wyoming. In the latter ores palladium is present also, and possibly, like the platinum, as arsenide. Potassium. — An abundant metal of the alkaline group. Found in many rocks, especially as a constituent of the feldspars, micas, and leucite. Nearly all terrestrial waters contain potassium, and the saline beds near Stassfurt, Germany, are peculiarly rich in it. Praseodymium. — A rare-earth metal associated with cerium. Radium. — A very rare metal of the calcium-barium group. Ob- tained in minute quantities from uraninite and carnotite. Of possible importance in the study of volcanism. According to R. J. Strutt , 1 traces of radium can be detected in all igneous rocks. Rhodium. — A metal of the platinum group. See “Platinum.” Rubidium —An. alkaline metal intermediate between potassium and caesium. Found in lepidolite and in some mineral springs. Rubidium is reported as present in the waters of the Caspian Sea. Ruthenium. — A metal of the platinum group. See “ Platinum.” Samarium.— A rare-earth metal obtained from samarskite. Scandium. — A rare-earth metal obtained from euxenite, and also from wolfram. According to G. Eberhard 2 it is the most widely diffused of all the rare-earth group, although it is found only in very small quantities. Selenium. — A nonmetallic element allied to sulphur, with which it is commonly associated. Found native, and also in the selenides of 1 Proc. Roy. Soc., vol. 77, ser. A, 1906, p. 472. 2 Sitzungsb. Berlin Akad., 1908, p. 851. See also a later paper in Chem. News, vol. 102, 1910, p. 211. On scandium in American wolfram, see H. S. Lukens, Jour. Am. Chem. Soc., vol. 35, 1913, p. 1470. 20 THE DATA OF GEOCHEMISTRY. copper, silver, mercury, lead, bismuth, and thallium. A few selenites exist as secondary minerals. Silicon. — Next to oxygen, the most abundant element. Found in quartz, tridymite, opal, and all silicates. The characteristic element of all important rocks except the carbonates. Silica also exists in probably all river, well, and spring waters. From volcanic waters it is deposited in the form of sinter. Silver. — This metal occurs native, as sulphide, arsenide, antimonide, telluride, chloride, bromide, iodide, and in numerous sulphosalts. Native gold generally contains some silver, and the latter is also often associated with native copper. Oxidized compounds of silver are known only as artificial products. Small traces of silver exist in sea water. Sodium. — The most abundant of the alkaline metals. In igneous rocks it is a constituent of the feldspars, of the nepheline group of minerals, and of certain pyroxenes, such as segirite. Also abundant in rock salt, and in nearly all natural waters, sea water especially. Strontium. — A metal intermediate between calcium and barium, but less abundant than the latter. Strontium in small amount is a common ingredient of igneous rocks. The most important strontium minerals are the sulphate, celestite, and the carbonate, strontianite. Sulphur. — Found native and in many sulphides and sulphates. Also in igneous rocks in the sulphatosilicates, hauynite and nosean. Native sulphur is abundant in volcanic regions, and is also formed elsewhere by the reduction of sulphates. Pyrite is the commonest of the sulphides, gypsum of the sulphates. Alkaline sulphates are obtainable from many natural waters. Sulphur also exists in coal and petroleum. Tantalum. — A rare acid-forming element akin to columbium, with which it is usually associated. Tellurium. — A semimetallic element, the least abundant of the sulphur group. Found native, and in the tellurides of gold, silver, lead, bismuth, mercury, nickel, and copper. Its oxide and a few rare tellurates or tellurites are known as alteration products. Terbium. — A rare-earth metal of the yttrium group. See “Yttrium.” Thallium. — One of the rarer heavy metals. Found as an impurity in pyrite and some other sulphides. The rare mineral crookesite is a selenide of copper and thallium, and lorandite is sulpharsenide of thallium. Yrbaite is a sulphide of arsenic, antimony, and thallium. Thorium. — A rare metal of the titanium-zirconium group, the most basic of the series. Chiefly obtained from monazite sand. Also known in silicates, such as thorite, in some columbo-tantalates, and in certain varieties of uraninite. THE CHEMICAL ELEMENTS. 21 Thulium. — A rare-earth metal of which little is known. Tin. — Very rare native. Most abundant as the oxide, cassiterite, which is found in association with granitic rocks. Traces of tin have been detected in feldspar. Stannite, or tin pyrites, is a sulphide of tin, copper, and iron, and a few other rare minerals contain this ele- ment. Titanium. — This element is almost invariably present in igneous rocks and in the sedimentary material derived from them. Out of 800 igneous rocks analyzed in the laboratory of the United States Geological Survey, 784 contained titanium. Its commonest occur- rences are as titanite, ilmenite, rutile, and perofskite. The element is often concentrated in beds of titanic iron ore. Tungsten— An acid-forming heavy metal allied to molybdenum. Found as tungstates of iron, manganese, calcium, and lead in the minerals wolfram, hubnerite, scheelite, and stolzite. TJranium. — A heavy metal found chiefly in uraninite, carnotite, samarskite, and a few other rare minerals. The phosphates, autunite and torbernite, are not uncommon in granites, and uraninite, although sometimes obtained from metalliferous veins, is more generally of granitic association. Carnotite occurs with sedimentary sandstones. Vanadium. — A rare element, both acid and base forming, and allied to phosphorus. Found in vanadates, such as vanadinite, descloizite, and pucherite, associated with lead, copper, zinc, and bismuth. Also in the silicates roscoelite and ardennite. Carnotite, which was men- tioned in the preceding paragraph, is an impure vanadate of potas- sium and uranium. Sulvanite is a sulphovanadate of copper. Patronite, a sulphide of vanadium, forms a large deposit at one locality in Peru. Xenon. — An inert gas, the heaviest member of the argon group. Found in minute traces in the atmosphere. Yttrium and ytterbium. — Two rare-earth metals, which, with lute- cium, 1 erbium, and terbium, are best obtained from gadolinite. Yttrium is also found in the phosphate, xenotime, in several silicates, and in some of the columbo-tantalate group of minerals. The min- erals of the rare earths are generally found in granite or pegmatite veins. Zinc. — Common and rather widely diffused. Native zinc has been reported, but its existence is doubtful. The sulphide, sphalerite, is its commonest ore, but the carbonate, smithsonite, and a silicate, calamine, are also abundant. At Franklin, New Jersey, zinc is found 1 The old ytterbium, the ytterbium of the first edition of this work, has been proved to he complex by G. Urbain and Auer von Welsbach, working independently. The two components of the former ytter- bium are by Urbain named neoytterbium and lutecium. For these Welsbach proposes the names alde- baranium and cassiopeium. The name ytterbium is here retained for the main component of the mixture and lutecium for the other, as having priority over its synonym. 22 THE DATA OF GEOCHEMISTRY. in a unique deposit, in which the oxide, zincite; the ferrite, frank- linite; and the silicates, troostite, and willemite, are the character- istic ores. Zirconium . — Allied to titanium and rather widely diffused in the igneous rocks. It usually occurs in the silicate, zircon. RELATIVE ABUNDANCE OF THE ELEMENTS. In any attempt to compute the relative abundance of the chemical elements, we must bear in mind the limitations of our experience. Our knowledge of terrestrial matter extends but a short distance below the surface of the earth, and beyond that we can only indulge in speculation. The atmosphere, the ocean, and a thin shell of solids are, speaking broadly, all that we can examine. For the first two layers our information is reasonably good, and their masses are approximately determined; but for the last one we must assume some arbitrary limit. The real thickness of the lithosphere need not be considered; but it seems probable that to a depth of 10 miles below sea level the rocky material can not vary greatly from the volcanic outflows which we recognize at the surface. This thickness of 10 miles, then, represents known matter, and gives us a quantita- tive basis for study. A shell only 6 miles thick would barely clear the lowest deeps of the ocean. I am indebted to Dr. R. S. Woodward for data relative to the volume of matter which is thus taken into account. The volume of the 10-mile rocky crust, including the mean elevation of the con- tinents above the sea, is 1,633,000,000 cubic miles, and to this material we may assign a mean density not lower than 2.5 nor much higher than 2.7. The volume of the ocean is put at 302,000,000 1 cubic miles, and I have given it a density of 1.03, which is a trifle too high. The mass of the atmosphere, so far as it can be deter- mined, is equivalent to that of 1,268,000 cubic miles of water, the unit of density. Combining these data, we get the following expressions for the composition of the known matter of our globe: Composition of known matter of the earth. Density of crust 2.5 2.7 Atmosphere per cent. . Ocean do Solid crust do 0. 03 7. 08 92. 89 0. 03 6.58 93. 39 100. 00 100.00 1 Sir John Murray (Scottish Geog. Mag., 1888, p. 39) estimates the volume of the ocean at 323,722,150 cubic miles. K. Karstens. more recently (Eine neue Berechnung der mittleren Tiefen der Oceane, Inaug. Diss., Kiel, 1894), put it at 1,285,935,211 cubic kilometers, or 307,496,000 cubic miles. Karstens gives a good summary of previous estimates, which vary widely. According to O. Kriimmel, the volume is 319,087,500 cubic miles (Encyc. Britannica, 11th ed., vol. 19, p. 974). To change the figure given in the text would be straining after unattainable precision. THE CHEMICAL ELEMENTS. 23 In short, we can regard the surface layer of the earth, to a depth of 10 miles, as consisting very nearly of 93 per cent solid and 7 per cent liquid matter, treating the atmosphere as a small correction to be applied when needed. 1 The figure thus assigned to the ocean is probably a little too high, but its adoption makes an allowance for the fresh waters of the globe, which are too small in amount to be estimable directly. Their insignificance may be inferred from the fact that a section of the 10-mile crust having the surface area of the United States represents only about 1.5 per cent of the entire mass of matter under consideration. A quantity of water equivalent to 1 per cent of the ocean, or 0.07 per cent of the matter now con- sidered, would cover all the land areas of the globe to a depth of 290 feet. Even the mass of Lake Superior thus becomes a negligible quantity. The significance of underground waters will be discussed later. The composition of the ocean is easily determined from the data given by Dittmar in the report of the Challenger expedition. 2 The maximum salinity observed by him amounted to 37.37 grams of salts in a kilogram of water, and by taking this figure instead of a lower average value we can allow for saline masses inclosed within the solid crust of the earth, which would not otherwise appear in the final estimates. Combining this datum with Dittmar’s figures for the average composition of the oceanic salts, we get the second of the subjoined columns. Other elements contained in sea water, but only in minute traces, need not be considered here. No one of them could reach 0.001 per cent. Composition of oceanic salts. NaCl 77.76 MgCl 2 10.88 MgS0 4 4. 74 CaS0 4 3. 60 k 2 so 4 2. 46 MgBr 2 22 CaC0 3 34 100. 00 Composition of ocean. 0 85.79 H 10.67 Cl 2. 07 Na 1. 14 Mg 14 Ca 05 K 04 S 09 Br 008 C 002 100. 00 It is worth while at this point to consider how large a mass of matter these oceanic salts represent. The average salinity of the ocean is not far from 3.5 per cent; its mean density is 1.027, and its volume is 302,000,000 cubic miles. The specific gravity of the salts, as nearly as can be computed, is 2.25. From these data it can be 1 The adoption of Murray’s figure for the volume of the ocean would make its percentage 7.12 to 7.88 according to the density (2.5 or 2.7) assigned to the lithosphere. 2 In vol. 1, Physics and chemistry. 24 THE DATA OF GEOCHEMISTRY. shown that the volume of the saline matter in the ocean is a little more than 4,800,000 cubic miles, or enough to cover the entire surface of the United States, excluding Alaska, 1.6 miles deep. 1 In the face of these figures, the beds of rock salt at Stassfurt and elsewhere, which seem so enormous at close range, become absolutely trivial. The allowance made for them by using the maximum salinity of the ocean instead of the average is more than sufficient, for it gives them a total volume of 325,000 cubic miles. That is, the data used for com- puting the average composition of the ocean and its average signifi- cance as a part of all terrestrial matter are maxima, and therefore tend to compensate for the omission of factors which could not well be estimated directly. The average composition of the lithosphere is very nearly that of the igneous rooks alone. The sedimentary rocks represent altered igneous material, from which salts have been leached into the ocean, and to which oxygen, water, and carbon dioxide have been added from the atmosphere. For these changes corrections can be applied, and their magnitude and effect, as will be shown later, is surprisingly small. The thin film of organic matter upon the surface of the earth can be neglected altogether. In comparison with the 10-mile thick- ness of rock below it, its quantity is too small to be considered. Even beds of coal are negligible, for their volume also is relatively insig- nificant. Practically, we have to consider at first only 10 miles of igneous rock, which, when large enough areas are studied, averages much alike in composition all over the globe. This point was estab- lished in an earlier memoir, when groups of analyses, representing rocks from different regions, were compared. 2 The essential uni- formity of the averages was unmistakable, and it has been still fur- ther emphasized in later computations by others as well as by myself. The following averages are now available for comparison: A. My original average of 880 analyses, of which 207 were made in the laboratory of the United States Geological Survey and 673 were collected from other sources. Many of these analyses were incomplete. B. The average of 680 analyses from the records of the Survey laboratories, plus some hundreds of determinations of silica, lime, and alkalies. The Survey data up to January 1, 1897. C. The average of 830 analyses from the Survey records, plus some partial deter- minations. The Survey data up to January 1, 1900. D. An average of all the analyses, partial or complete, made up to January 1, 1914, in the laboratories of the Survey. 3 1 According to J. Joly (Sci. Trans. Roy. Soc. Dublin, 2d ser., vol. 7, 1899, p. 30) the sodium chloride in the ocean would cover the entire globe 112 feet deep. If Krummel’s figure for the volume of the ocean is taken, the volume of the salts becomes approximately 5,100,000 cubic miles. 2 Bull. Philos. Soc. Washington, vol. 11, 1889, p. 131. Also in Bull. U. S. Geol. Survey No. 78, 1891, p. 34. A later and more complete table is given in Proc. Am. Philos. Soc., vol. 51, p. 214, 1912. W. J. Mead (Jour. Geology, vol. 22, 1914, p. 772) by a graphic method has obtained an average composition of the igneous rocks very near to mine. 3 See Bull. U. S. Geol. Survey No. 588, 1915, p. 20, for details. THE CHEMICAL ELEMENTS. 25 E. An average, computed by A. Harker, 1 of 536 analyses of igneous rocks from British localities. Many of these analyses were incomplete, especially with respect to phosphorus and titanium. F. An average of 1, 811 analyses, from Washington’s tables. 2 Calculated by H. S. Washington. The data represent material from all parts of the world. Now, omitting minor constituents, which rarely appear except in the more modern analyses, these averages may be tabulated together, although they are not absolutely comparable. The comparison as- sumes the following form: Average composition of igneous rocks. Clarke. Harker. Washing- ton. A B c D E F Si0 2 58. 59 59. 77 59. 71 60. 86 58. 98 58. 239 A1 2 0 3 15. 04 15. 38 15. 41 15. 17 15. 41 15. 796 Fe 2 0 3 3. 94 2. 65 2. 63 2. 70 4. 78 3. 334 FeO 3. 48 3. 44 3. 52 3. 52 2. 70 3. 874 MgO 4. 49 4. 40 4. 36 3. 88 3. 71 3. 843 CaO 5. 29 4. 81 4. 90 4. 93 4. 83 5. 221 Na 2 0 3. 20 3. 61 3. 55 3. 44 3. 18 3. 912 KoO 2. 90 2. 83 2. 80 3. 05 2. 77 3. 161 H 2 0 at 100° 1 1.96 . 48 'I .363 H 2 0 above 100° 1. 51 1. 52 1. 45 f 2. 17 1.428 Ti0 2 •. 55 .53 .60 .80 .52 1.039 p 2 o 6 .22 .21 .22 .29 .21 .373 99. 66 99. 14 99. 22 100. 57 99. 26 100. 583 Although these six columns are not very divergent, they exhibit differences which may be more apparent than real. Differences of summation are due partly to the omission of minor constituents, but the largest variations are attributable to the water. In two columns hygroscopic water is omitted; in two it is not distinguished from combined water; in two a discrimination is made. By rejecting the figures for water and recalculating to 100 per cent the averages become more nearly alike, as follows : Average composition of igneous rocks , reduced to uniformity. A B c D E F Si0 2 -.: 59. 97 61. 22 61. 12 61. 69 60. 76 58. 96 ALO, 15. 39 15. 75 15. 77 15. 38 15. 87 15. 99 Fe 2 0 3 4. 03 2. 71 2. 69 2. 74 4. 92 3. 37 FeO 3. 56 3. 53 3. 60 3. 57 2. 78 3. 93 MgO 4. 60 4. 51 4. 46 3. 93 3.82 3. 89 CaO 5. 41 4. 93 5. 02 4. 99 4.. 97 5. 28 Na 2 0 3. 28 3. 69 3. 63 3. 49 3. 28 3. 96 K 2 0 2. 97 2. 90 2. 87 3. 10 2. 85 3. 20 Ti0 2 . 56 . 54 . 61 . 81 . 53 1. 05 PXL .23 .22 .23 .30 .22 .37 2 5 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 1 Tertiary igneous rocks of the Isle of Skye: Mem. Geol. Survey United Kingdom, 1904, p. 416. An earlier average appears in Geol. Mag., 1899, p. 220. 2 Prof. Paper U. S. Geol. Survey No. 14, 1903, p. 106. In this average and in Harker's there are figures for manganese, which I leave temporarily out of account. On the average composition of Minnesota rocks see F. F. Grout, Science, vol. 32, 1910, p. 312. 26 THE DATA OP GEOCHEMISTRY. Of the averages, only D and F need be considered any further, for they include the largest masses of trustworthy data. A was only a preliminary computation; B and C are included under D. Harker’s average contains too many incomplete analyses. D and F, however, are not strictly equivalent. Washington’s average relates only to analyses which were nominally complete and made in many labora- tories by very diverse methods. My average represents the homo- geneous work of one laboratory, and includes, moreover, many partial determinations. For the simpler salic rocks determinations of silica, lime, and alkalies are generally all that is needed for petrographic purposes. The femic rocks are mineralogically more complex, and for them full analyses are necessary. The partial analyses, there fore, represent chiefly salic rocks, and their inclusion in the average tends to raise the percentage of silica and to lower the proportions of other elements. The salic rocks, however, are more abundant than those of the other class, and so the higher figure for silica seems more probable. This conclusion is in line with the criticisms of F. P. Mennell , 1 who thinks that the femic rocks received excessive weight in my earlier averages. Mennell has studied the rocks of southern Africa, where granitic types are predominant, and believes that the true average should approximate the composition of a granite. His criticisms are entitled to serious consideration, but they are not absolutely conclusive. A study of the composition of river waters originating in areas of crystalline rocks reveals a preponderance of calcium over alkalies which waters from purely granitic environment could hardly possess. Granitoid rocks, such, for example, as quartz monzonite, are also abundant, and the average composition is likely to be near that of a diorite or andesite . 2 The whole land surface of the earth must be taken into account before the true average can be finally . ascertained . So far, the final average has only been partly given; the minor con- stituents of the rocks remain to be taken into account. In the labor- atory of the Geological Survey the analyses of igneous rocks have been unusually elaborate, and many things have been determined that are too often ignored. The complete average is given in the next table, with the number of determinations to which each figure corresponds. In the elementary column hygroscopic water does not appear, but 1 Geol. Mag., 1904, p. 263; 1909, p. 212. For other discussions of the data given in my former papers see L. De Launay, Revue gen. sci., Apr. 30, 1904; and C. Ochsenius, Zeitschr. prakt. Geologie, May, 1898. Com- pare also R. A. Daly (Bull. U. S. Geol. Survey No. 209, 1903, p. 110), who argues that the universal or funda- mental magma is approximately basaltic. 2 F. Loewinson-Lessing (Geol. Mag., 1911, p. 248) argues in favor of two fundamental magmas, the grani- toid and gabbroid. These are thought to be present in about equal proportions in the lithosphere, and then- average composition is close to that found by Clarke and Washington. On the mean atomic weight of the earth’s crust see L. De Launay, Compt. Rend., vol. 150, 1910, p. 1270. See also A. E. Fersmann (Bull. Acad. St. Petersburg, 1912, p. 367) for a calculation of the atomic percentages of the more important rock- forming elements. THE CHEMICAL ELEMENTS. 27 an allowance is made for a small amount of iron which was reported in the analyses as FeS 2 . When a “ trace” of anything is recorded, it is arbitrarily reckoned as 0.01 per cent, and when a substance is known to be absent from a rock, by actual determination of the fact, it is assigned zero value in making up the averages. 1 Average composition of igneous rocks in detail. Number of determina- tions. Average. Reduced to 100 per cent. In elementary form. SiCL 1,714 60. 86 59. 83 0 47. 29 ALfL 1 , 193 15. 17 14. 98 Si 28. 02 Fe^Oo l' 242 2. 70 2. 65 A1 7. 96 FeO l' 238 3. 52 3. 46 Fe 4. 56 MeO 1, 328 3. 88 3. 81 Mg 2. 29 CaO 1, 564 4. 93 4. 84 Ca 3. 47 Na^O 1,632 3. 44 3. 36 Na 2. 50 K 2 0 1, 624 3. 05 2. 99 K 2. 47 H 2 0- 912 .48 .47 H . 16 HoO-r 959 1. 45 1. 42 Ti .46 - i - a - 2 v '' 1 - Ti0 2 1, 140 .80 . 78 Zr .017 ZrOo 372 .023 .023 C .13 CO, 730 .49 .48 P . 13 vv/ 2 ------------------- PXL 1, 136 .29 .29 S . 103 s!f" v 814 . 104 .102 Cl .063 Cl 265 .064 . 063 F . 10 F 112 . 10 .10 Ba .092 BaO 793 . 104 . 102 Sr .033 SrO 649 .04 .04 Mn .078 MnO 1, 155 .10 . 10 Ni .020 NiO. 299 .026 .025 Cr .033 Cr o 0o . 293 .050 .049 y . 017 y o 0 , 102 .026 .025 Li .004 Li 2 0 581 .011 .011 101. 708 100. 000 100. 000 In this computation the figures for C, Zr, Cl, F, Ni, Cr, and V are probably a little too high. They show, however, that these elements exist in igneous rocks in determinable quantities. Fluorine, however, exists in rocks chiefly in the mineral apatite, and its proportion can be determined with much probability from the percentage of phos- phorus. Computing from that datum, the percentage of fluorine becomes only 0.027, or little more than one-fourth of the figure given in the table. As for carbon, its probable excess may be allowed to stand, as a compensation, in our final reckoning, for the otherwise undeterminable quantities represented by coal and petroleum. The elements not included in the calculation represent minor corrections, to be applied whenever the necessity for doing so may arise. For estimates of their probable amounts, the papers by J. H. L. Vogt 2 1 In this table all analyses of igneous rocks made in the laboratory of the Survey down to Jan. 1, 1914, have been utilized. 2 Zeitschr. prakt. Geologie, 1898, pp. 225, 314, 377, 413; 1899, pp. 10, 274. 28 THE DATA OF GEOCHEMISTRY. and J. F. Kemp 1 can be consulted. A few more definite estimates have been made by Clarke and Steiger 2 from careful analyses of large com- posite samples of rocks and clays.- The average percentages are as follows: CuO, 0.0130; ZnO, 0.0049; PbO, 0.0022; As 2 0 5 , 0.0005. These figures, considered as orders of magnitude, have a high degree of probability. The remaining elements not mentioned here nor in the table can not amount to more than 0.5 per cent altogether, and even that small figure is likely to be an overestimate. Before we can finally determine the composition of the lithosphere, the sedimentary rocks are to be taken into account ; and to do this we must ascertain their relative quantity. First, however, we may con- sider their composition, which has been determined by means of com- posite analyses. That is, instead of averaging analyses, average mixtures of many rocks were prepared, 3 and these were analyzed once for all. The results appear in the next table. Composite analyses of sedimentary rocks. A. Composite analysis of 78 shales; or, more strictly, the average of two smaller composites, properly weighted. B. Composite analysis of 253 sandstones. C. Composite analysis of 345 limestones. Si0 2 . A1 2 0 3 FeO.. MgO. CaO.. Na 2 0. H 2 0 at 110°.... H 2 0 above 110 c Ti0 2 C0 2 p 2 o 5 S so 3 Cl BaO SrO MnO Li 2 0 C, organic A B C 58. 38 78. 66 5. 19 15. 47 4. 78 .81 4. 03 1. 08 \ .54 2. 46 .30 / 2. 45 1. 17 7. 90 3. 12 5. 52 42. 61 1. 31 .45 .05 3. 25 1. 32 .33 1. 34 .31 .21 3. 68 «1. 33 a . 56 .65 .25 .06 2. 64 5. 04 41. 58 .17 .08 .04 .09 .65 .07 .05 Trace. .02 : 05 .05 None. None. None. None. Trace. Trace. .05 Trace. Trace. Trace. .81 100. 46 100. 41 100. 09 a Includes organic matter. 1 Science, Jan. 5, 1906; Econ. Geology, vol. 1, 1905, p. 207. See also a curious paper by W. Ackroyd, in Chem. News, vol. 86, 1902, p. 187. W. N. Hartley and H. Ramage (Jour. Chem. Soc., vol. 71, 1897, p. 533) have shown that some of the rarest elements, such as gallium and indium, are widely diffused in rocks and minerals. W. Vernadsky (Chem. Zentralbl., vol. 2, 1910, p. 1775) has also found that indium, thallium, gallium, rubidium, and caesium are widely distributed in spectroscopic traces. Vernadsky (Centralbl. Min.. Geol. u. Pal., 1912, p. 758) has also studied the occurrence of native elements in the earth’s crust. 2 Jour. Washington Acad. Sci., vol. 4, p. 57, 1914. 3 These mixtures were prepared by G. W. Stose, under the direction of G. K. Gilbert. The analyses were made by H. N. Stokes in the laboratory of the U. S. Geological Survey. See Bull. U. S. Geol. Survey No. 228, 1904, p. 20. THE CHEMICAL ELEMENTS. 29 In attempting to compare these analyses with the average composi- tion of the igneous rocks, we must remember that they do not repre- sent definite substances, but mixtures shading into one another. The average limestone contains some clay and sand; the average shale contains some calcium carbonate. Furthermore, they do not cover all the products derived from the decomposition of the primitive rock, for the great masses of sediments on the bottom of the ocean are left out of account. There are also metamorphic rocks to be considered, such as chloritic and talcose schists, amphibolites, and serpentines; although their quantities are presumably too small to seriously modify the final averages. They might, however, help to explain a deficiency of magnesium which appears in the sedimen- tary analyses. Partly on account of these considerations, and partly because the sedimentary rocks contain water and carbon diox- ide which have been added to the original igneous material, we can not recombine the composite analyses so as to reproduce exactly the com- position of the primitive matter. 1 To do this is would be necessary also to allow for the oceanic salts, which represent, in part, at least, losses from the land; but that factor in the problem is perhaps the least embarrassing. Its magnitude is easily estimated, and it gives a measure of the extent to which the igneous rocks have been decomposed. If we assume that all the sodium in the ocean was derived from the leaching of the primitive rocks, and that the average composition of the latter is correct as stated, it is easy to show that the marine portion is very nearly one-thirtieth of that contained in the 10-mile lithosphere. That is, the complete decomposition of a shell of igneous rock one-third of a mile thick would yield all the sodium in the ocean. Some sodium, however, is retained by the sediments, and the analyses show that it is about one-third of the total amount. That is, the oceanic sodium represents two-thirds of the decomposition, and the estimate must therefore be increased one-half. On this basis, a rocky shell one-half mile thick, completely enveloping the globe, would slightly exceed the amount needed to furnish the sodium of the sea and the sediments. In order to make this estimate more precise, let us consider the detailed figures. The maximum allowance for the sodium in the ocean is 1.14 per cent. From my average the mean percentage of sodium in the igneous rocks is 2.50; Washington’s figures give 2.90. Now, putting the ocean at 7 per cent and the lithosphere at 93 per cent of the known matter, the following ratios between oceanic sodium and rock sodium are easily computed: Clarke, 1 : 29.8; Washington, 1 : 33.9. Hence, the sodium in the ocean corresponds 1 For an elaborate attempt in this direction, see C. R. Van Hise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 947-1002. 30 THE DATA OF GEOCHEMISTRY. to a volume of igneous rocks, according to the first ratio, of 54,800,000 cubic miles or, for the second estimate, of 48,200,000 cubic miles. Suppose, however, that the average analyses do not represent the true composition of the primitive lithosphere. We may then test our figures by another assumption, namely, that the real average lies somewhere between two evident extremes — the composition of a rhyolite and that of a basalt. In 100 rhyolites, as shown in Wash- ington’s tables, the average percentage of sodium is 2.58, while for 220 basalts it is 2.40. These figures give ratios of 1 : 30.1 and 1 : 28.4, corresponding to rock volumes of 54,200,000 and 57,500,000 cubic miles, respectively — quantities of quite the same order as those previously calculated. From the composite analyses of the sedimentary rocks the cor- rection for their retained sodium can be determined. This sodium is chiefly, but not entirely, in the shales, and its amount is less than 1 per cent, with a probable value of 0.90. This is 35 per cent of the total sodium in the average igneous rock, and the oceanic sodium represents the 65 per cent removed by leaching. Allowing for this sedimentary sodium, the total sodium of the ocean and of the sedi- mentary rocks is represented by the ratio of 65 : 100 = 54,800,000 : 84,300,000, the last term giving the number of cubic miles of igneous rock which has undergone decomposition. This quantity is that of a rock shell completely enveloping the globe and 0.4215 mile, or 2,225 feet, thick. If we accept the highest ratio of all, that furnished by the average basalt, the thickness may be raised to 2,336 feet, while Washington’s data will give a much lower figure. A further allow- ance of 10 per cent, which is excessive, for the increase in volume due to oxidation, carbonation, and absorption of water will raise the thickness assignable to the sedimentaries from 2,225 to 2,447 feet, an amount still short of the half-mile estimate. No probable change in the composition of the lithosphere can modify this estimate very considerably; and since the ocean may contain primitive sodium, not derived from the rocks, the half mile must be regarded as a maximum allowance. If the primeval rocks were richer in sodium than those of the present day, a smaller mass of them would suffice ; if poorer, more would be needed to account for the salt in the sea. Of the two suppositions, the former is the more probable ; but neither assumption is necessary. If, however, we assume that our igneous rocks are not altogether primary but that some of them represent re-fused or metamorphosed sedimentaries, we must conclude that they have been partly leached and have therefore lost sodium. That is, the original matter was richer in sodium, and the half-mile estimate is conse- quently much too large. THE CHEMICAL ELEMENTS. 31 From another point of view, the thinness of the sediments can be simply illustrated. The superficial area of the earth is 199,712,000 square miles, of which 55,000,000 are land. According to Geikie, 1 the mean elevation of all the continents is 2,411 feet. Hence, if all the land now above sea level, 25,000,000 cubic miles, were spread uni- formly over the globe, it would form a shell about 660 feet thick. If we assume this matter to be all sedimentary, which it certainly is not, and add to it any probable allowance for the sediments at the bottom of the sea we shall still fall far short of the half-mile shell which, on chemical evidence, is a maximum. In the following calculation this maximum will be taken for granted. The relative proportions of the different sedimentary rocks within the half-mile shell can only be estimated approximately. Such an estimate is best made by studying the average igneous rock and deter- mining in what way it can break down. A statistical examination of about 700 igneous rocks, which have been described petrographic ally, leads to the following rough estimate of their mean mineralogical composition : Quartz 12.0 Feldspars 59. 5 Hornblende and pyroxene 16. 8 Mica.- 3. 8 Accessory minerals 7. 9 100.0 The average limestone contains 76 per cent of calcium carbonate, and the composite analyses of shales and sandstones correspond to the subjoined percentages of the component minerals: Average composition of shale and sandstone. Shale. Sandstone. Quartz a 22. 3 66. 8 Feldspar 30. 0 11. 5 Clay & 25. 0 6. 6 Limonite 5. 6 1. 8 Carbonates 5. 7 11. 1 Other minerals 11.4 2.2 100.0 100.0 a The total percentage of free silica. b Probably sericite in part. In that case the feldspar figure becomes lower. If, now, we assume that all of the igneous quartz, 12 per cent, has become sandstone, it will yield 18 per cent of that rock, which is evidently a maximum. Some quartz has remained in the shales. 1 Textbook of geology, 4th ed., vol. 1, 1903, p. 49. 32 THE DATA OF GEOCHEMISTRY. One hundred parts of the average igneous rock will form, on decom- position, less than 18 parts of sandstone. The igneous rocks contain as shown in the last analysis cited, 4.84 per cent of lime. This would form 8.65 per cent of calcium carbon- ate, or 11.2 per cent of an average limestone. But at least half of the lime has remained in the other sediments, so that its true propor- tion can not reach 6 per cent, or one-third the proportion of the sandstones. The remainder of the igneous material, plus some water and minus oceanic sodium, has formed the siliceous residues which are grouped under the vague title of shale. Broadly, then, we may estimate that the lithosphere, within the limits assumed in this me- moir, contains 95 per cent of igneous rock and 5 per cent of sedimen- taries. If we assign 4.0 per cent to the shales, 0.75 per cent to the sandstones, and 0.25 per cent to the limestones, we shall come as near the truth as is possible with the present data. 1 On this basis, the average composition of the lithosphere may be summed up as shown in the following table. The analyses of the sedimentary rocks are recalculated to 100 per cent. Average composition of the lithosphere. Igneous (95 per cent). Shale (4 per cent). Sandstone (0.75 per cent). Limestone (0.25 per cent). Weighted average. Si0 2 59. 83 58. 10 78. 33 5. 19 59. 77 ai 2 o 3 14. 98 15.40 4. 77 .81 14. 89 Fe 2 0 3 2. 65 4. 02 1. 07 . 54 2. 69 FeO 3. 46 2. 45 . 30 3. 39 MgO 3. 81 2.44 1. 16 7. 89 3. 74 CaO 4. 84 3. 11 5. 50 42. 57 4. 86 Na 2 0 3. 36 1. 30 .45 .05 3. 25 K 2 0 2. 99 3. 24 1. 31 .33 2. 98 h 2 o ' 1.89 5. 00 1. 63 .77 2. 02 Ti0 2 . 78 .65 .25 .06 . 77 Zr0 2 .02 . 02 co 2 .48 2. 63 5. 03 41. 54 . 70 p 2 o 5 .29 . 17 .08 .04 .28 s . 11 .09 . 10 so 3 . 64 . 07 . 05 . 03 Cl . 06 . 02 .06 F . 10 . 09 BaO . 10 . 05 . 05 . 09 SrO . 04 . 04 MnO . 10 . 05 .09 NiO . 025 . 025 Cr 2 0 3 . 05 . 05 V 9 0, . 025 . 025 Li 2 0 . 01 .01 C . 80 .03 100. 000 100. 00 100. 00 100. 00 100. 000 1 C. R. Van Hise (A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, p. 940) divides the sedimentary rocks into 65 per cent shales, including all pelites and psephites, 30 per cent sandstones, and 5 per cent limestones. W. J. Mead (Jour. Geology, vol. 15, 1907, p. 238), by a graphic process, dis- tributes the sedimentaries into 80 per cent shales, 11 per cent sandstones, and 9 per cent limestones. THE CHEMICAL ELEMENTS. 33 The final average differs from that of the igneous rocks alone only within the limits of uncertainty due to experimental errors and to the assumptions made as to the relative proportions of the sedimentaries. The values chosen for the sediments are approximations only, and nothing more can be claimed for them. They seem to be near the truth — as near as we can approach with data which are necessarily imperfect — and so they may be allowed to stand without further emendation. In the preceding table the hygroscopic water of the igneous rocks is taken into account, but so far the underground waters have been neglected. For this omission the hygroscopic water may partly compensate, but the subject demands a little closer attention. Extravagant estimates of the quantity of underground water have been made, based upon the fact that all rocks are more or less porous. 1 Van Hise, however, claims that the pore spaces below a depth of 6 miles are probably closed by the pressure of the superincumbent strata; a consideration which must not be ignored. Van Hise estimates the volume of the underground waters to a depth of 10,000 meters as equal to that of a sheet covering the continental areas 69 meters or 226 feet deep. Fuller’s estimate is more complete, for it involves a discussion of the relative quantities and average porosities of the sedimentary and igneous rocks, and he concludes that the volume of subterranean water is about one one-hundredth that of the ocean. These conclusions require some modification; for Adams, by experiments upon the compression of granite, has shown that porosity may exist to a depth of at least 11 miles. In any case the quantity of water is negligible, for, added to the volume of the hydrosphere it would not appreciably affect the final computation. The proportion of water in known terrestrial matter would be in- creased by less than 0.1 per cent. With the data now before us we are in a position to compute the relative abundance of the chemical elements in all known terrestrial matter. For this purpose, the composition of the lithosphere is restated in elementary form, with an arbitrary allowance of 0.5 per cent for all the elements not specifically named. As for the atmos- phere, 0.03 per cent, it is represented in the final results as if it were all nitrogen; an exaggeration which allows for the traces of nitrogen, 1 See A. Delesse, Bull. Soc. g£ol. France, vol. 29, 1861, p. 64; J. D. Dana, Manual of geology, 4th ed., 1895, p. 209; W. B. Greenlee, Am. Geologist, vol. 18, 1896, p. 33; O. Keller, Annales des mines, 9th ser., vol. 12, 1897, p. 32; C. S. Slichter, Water-Supply Paper U. S. Geol. Survey No. 67, 1902, p. 14; T. C. Cham- berlin and R. D. Salisbury, Geology, vol. 1, 1904, p. 209; C. R. Van Hise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, p. 129; M. L. Fuller, Water-Supply Paper U. S. Geol. Survey No. 160, 1906, p. 59; F. D. Adams, Jour. Geology, vol. 20, 1912, p. 97. See also an address by J. F. Kemp, Trans. Am. Inst. Min. Eng., vol. 14, 1914, p. 3. 97270°— Bull. 616—16 3 34 THE DATA OF GEOCHEMISTRY. rarely determined, that are present in the rocks. 1 The mean com- position of the lithosphere, the hydrosphere, and the atmosphere, then, is as follows : Average composition of known terrestrial matter. Lithosphere, 93 per cent. Hydrosphere, 7 per cent. Average, in- cluding atmos- phere. Oxygen 47.33 85. 79 50. 02 25. 80 7. 30 Silicon 27. 74 Aluminum 7. 85 Iron 4. 50 4. 18 3. 22 2. 08 2. 36 Calcium 3. 47 . 05 Magnesium 2. 24 . 14 Sodium 2. 46 1. 14 Potassium 2. 46 . 04 2. 28 . 95 Hydrogen . 22 10. 67 Titanium .46 . 43 Carbon . 19 .002 .18 .20 Chlorine .06 2. 07 Bromine .008 Phosphorus . 12 . 11 Sulphur . 12 .09 . 11 Barium .08 .08 Manganese .08 .08 Strontium .02 .02 Nitrogen .03 Fluorine . 10 . 10 All other elements .50 .47 100. 00 100. 000 100. 00 The briefest scrutiny of the foregoing tables will show that in the lithosphere the lighter elements predominate over the heavier. All the abundant elements fall below atomic weight 56, and above that, in the analyses given on page 27, only nickel, zirconium, strontium, and barium appear. The heavy metals, as a rule, occur in apparently trivial quantities. Since, however, the mean density of the earth is about double that of the rocks at its surface, it has sometimes been supposed that the heavier substances may be con- centrated in its interior, a supposition which is possibly true, but unprovable. If the globe is similar in constitution to a meteorite, we should expect iron and nickel to be abundant in its mass as a whole ; but this, after all, is nothing more than a suspicion. One fact only seems to shed a clear light upon the problem. A mixture of all the elements, in equal proportions by weight and in the free state, would have a density greater than that of the earth. Combination 1 See A. D. Hall and N. J. H. Miller (Jour. Agr. Sci.,vol. 2, p. 343), on nitrogen in unweathered sedi- mentary rocks. From 0.04 to 0.107 per cent was found. H. Erdmann ( Ber. Deutsch. chem. Gesell., vol. 29, 1896, p. 1710) found traces of nitrogen in several rare minerals from pegmatite. In a later paper, in Arbeiten auf den Gebieten der Gross-Gasindustrie, No. 1, 1909, Erdmann computes that each square meter of land, to a depth of 15 kilometers, contains 5 metric tons of nitrogen. The total amount of nitrogen in the rocks is much less than that in the atmosphere alone. THE CHEMICAL ELEMENTS. 35 would increase the density of the mixture, and the effect of internal pressure would make it greater still. It is therefore plain that in the earth as a whole, whatever may he the composition or condition of its interior, the lighter elements are more abundant than the denser. Thus far we can go, but no farther. Of the actual propor- tions we know nothing. THE PERIODIC CLASSIFICATION. Although the chemical elements are analytically distinct, they are by no means unrelated. On the contrary, they fall into a number of natural groups; and within each one of these the members not only form similar compounds, but also exhibit, as a rule, a regular grada- tion of properties. This relationship has led to an important gen- eralization — the periodic law, or, more precisely, the periodic classi- fication of the elements — and in its light some of their associations become extremely suggestive. When the elements are tabulated in the order of their atomic weights, the periodicity shown in the following scheme at once be- comes evident : Periodic classification of the elements. a 36 THE DATA OF GEOCHEMISTRY. 05 iO od 05 O vO lO S 3 2 rC 73 Ph Pm 2 £ § C5 ^ r* Q PQ m pq CS3 lO a ii ^ C$ P3 Q 0> Q w £ M « In this table the atomic weights are rounded oil from the more precise numbers. THE CHEMICAL ELEMENTS. 37 In each vertical column the elements are closely allied, forming the natural groups to which reference has already been made. The alkaline metals; the series calcium, strontium, and barium; the car- bon group, and the halogens are examples of this regularity. In other words, similar elements appear at regular intervals and occupy similar places. If we follow any horizontal line of the table from left to right, a progressive change of valency is shown, and in both directions a systematic variation of properties is manifested. Broadly stated, the properties of the elements, chemical and physical, are periodic functions of their atomic weights, and this is the most gen- eral expression of the periodic law. At certain points in the table gaps are left, and these are believed to correspond to unknown ele- ments. For three of the spaces which were vacant when Mendeleef announced the law, he ventured to make specific predictions, and his prophesies have been verified. The elements scandium, gallium, and germanium were described by him in advance of their actual dis- covery, and in every essential particular his predictions were correct. Atomic weights, densities, melting points, and the character of the compounds which the metals should form were foretold, and in each case with a remarkable approximation to accuracy. This power of prevision is characteristic of all valid generalizations, and its exhi- bition in the periodic system led to the speedy adoption of the latter. Even radium and its emanation, niton, fall into their proper places in fine with their near relatives, barium and argon. An elaborate discussion of the periodic law would be out of place in a memoir of this kind, and its details must be sought elsewhere . 1 Only its application to geochemistry can be considered now. In the first place, on looking at the table vertically it is noticeable that members of the same elementary group are commonly associated in nature. That is, similar elements have similar properties, form similar compounds, and give similar reactions, and because of the conditions last mentioned they are usually deposited together. Thus the platinum metals are seldom found apart from one another; the rare earths are invariably associated; chlorine, bromine, and iodine occur under closely analogous circumstances; selenium is obtained from native sulphur; cadmium is extracted from ores of zinc, and so on through a long list of regularities. The group relations govern many of the associations which we actually observe, although they are modified by the conditions which influence chemical union. Even here, however, regularities are still apparent. In combination unlike elements seek one another, and yet there appears to be a preference 1 See especially F. P. Venable, Development of the periodic law, Easton, Pennsylvania, 1896. The larger manuals of chemistry all discuss the law somewhat fully. T. Carnelley (Ber. Deutsch. chem. Gesell., vol. 17, 1884, p. 2287) has especially studied the bearings of the periodic law on the occurrence of the elements in nature. 38 THE DATA OF GEOCHEMISTRY. for neighbors rather than for substances that are more remote. For example, silicon follows aluminum in the order of atomic weights, and silicates of aluminum are by far the most abundant minerals. The next element in order is phosphorus, and aluminum phosphates are more common and more numerous than the precisely similar arse- nates. On the other hand, copper, whose atomic weight is nearer that of arsenic, oftener forms arsenates, although its phosphates are also known. An even more striking example is furnished by the compounds of the elementary series oxygen, sulphur, selenium, and tellurium. Oxides >nd oxidized salts of many elements are found in the mineral kingdom, and most commonly of metals having low atomic weights. From manganese and iron upward, sulphides are abundant ; but selenium and tellurium are more often united with the heavier metals silver, mercury, lead, or bismuth, and tellurium with gold. The elements of high atomic weight appear to seek one another, a tendency which is indicated in many directions, even though it can not be stated in the form of a precise law. The general rule is evident, but its significance is not so clear. We have already seen that the most abundant elements are among those of relatively low atomic weight, and this observation may be verified still further. In general, with some exceptions, the abun- dance of an element within a group depends on its atomic weight, but not in a distinctly regular manner. For instance, in the alkaline series, lithium is widely diffused in small quantities, sodium and potas- sium are very abundant, rubidium is scarce, and caesium is the rarest of all. The same rule holds in the tetrad group — carbon, silicon, titanium, zirconium, and thorium; and in the halogens — fluorine, chlorine, bromine, and iodine. In each of these series the abundance increases from the first to the second member and then diminishes to the end. In the oxygen group, however, the first member is much the most abundant and after that a steady decrease to tellurium is shown. An exception to the rule is found in the metals of the alka- line earths, for strontium is less abundant than barium, at least so far as our evidence now goes. Other exceptions also seem to exist, but they are possibly apparent and not real. In the light of better data than we now possess the anomalies may disappear. Here again we are dealing with an evident tendency of which the meaning is yet to be discovered. That the abundance and associations of the ele- ments are connected with their position in the periodic system seems, however, to be clear. The coincidences are many, the exceptions are comparatively few. So much for the chemical side of the question. On the geological side other considerations must be taken into account, and it is easily seen that the periodic law covers only a part of the elementary asso- ciations. Rocks are formed from magmas in which many and com- THE CHEMICAL ELEMENTS. 39 plex reactions are possible and the simpler rules governing single minerals are no longer directly applicable. Some regularities, how- ever, can be recognized, and certain elements are in a sense character- istic of certain kinds of rock. In the summary already given some of these regularities are indicated. They have been generalized by J. H. L. Vogt 1 somewhat as follows: In the highly siliceous rocks we find the largest proportions of the alkalies, of the rare earths, and of the elements glucinum, tungsten, molybdenum, uranium, colum- bium, tantalum, tin, zirconium, thorium, boron, and fluorine. The rocks low in silica are richer in the alkaline earths, and in magne- sium, iron, manganese, chromium, nickel, cobalt, vanadium, titanium, phosphorus, sulphur, chlorine, and the platinum metals. To some extent, of course, these groups overlap, for between the two rock classes no definite line can be drawn. But the minerals of the rare earths, with the columbo-tantalates, tinstone, beryl, etc., seldom if ever occur except in rocks which approach the granites in general composition; whereas chromium, nickel, and the platinum metals are most commonly associated with peridotites or serpentines. For these differences in distribution no complete, explanation is at hand; but they are probably due to differences of solubility. If we conceive of a mediosilicic magma in process of differentiation into a salic and a femic portion, the minor constituents will evidently tend to con- centrate, each in the magmatic fraction in which it is most soluble. Solubilities of this order are yet to be experimentally studied. METEORITES. The supposed analogy between the earth as a whole and an enor- mous meteorite has already been mentioned. A brief statement of the chemical nature of meteorites is therefore not out of place here. All known meteorites may be divided into three classes — iron meteor- ites, stony meteorites, and carbonaceous meteorites. The last class, so far as direct observation goes, is very small, and need not be con- sidered further. It is possible that carbonaceous meteorites may be numerous but commonly consumed before reaching the surface of the earth, a supposition, however, which can only be entertained as a speculation. The two principal classes of meteorites merge into one another, so that we have irons, stones, and all sorts of intermediate mixtures. The irons consist mainly of iron and nickel, with variable and minor admixtures of graphite, schreibersite, troilite, etc. The terrestrial nickel-iron of Ovifak in Greenland resembles meteoric iron in every essential particular. It is, therefore, often mentioned, as possibly typical of the material which forms the centrosphere. 1 Zeitschr. prakt. Geologie, 1898, p. 324. H. S. Washington (Trans. Am. Inst. Min. Eng., vol. 39, 1909, p. 735) has made a rather elaborate study of the distribution of the commoner elements with reference to the different magmas. 40 THE DATA OF GEOCHEMISTRY. The stony meteorites almost, if not quite invariably, contain dis- seminated particles of nickel-iron, but otherwise are analogous to rocks found on the surface of the earth. They are, however, not like the predominant rocks of the lithosphere. Their average composi- tion has been calculated by G. P. Merrill 1 from 99 published analyses of stony meteorites, with the subjoined results. The first column of figures gives the actual average; the second is recalculated to 100 per cent after rejecting the admixed nickel-iron, sulphides, and phosphides. Average composition of stony meteorites. Found. Recalculated. Si0 2 38. 98 45. 46 A1 2 0 3 2. 75 3. 21 Fe 11. 61 FeO 16. 54 19. 29 CaO 1. 77 2. 06 MgO 23. 03 26. 86 Na 2 0 . 95 1. 11 K 2 0 . 33 . 38 MnO . 56 . 65 Chromite . 84 .98 Ni, Co 1. 32 s 1. 85 P . 11 100. 64 100. 00 From this computation it appears that the stony meteorites have essentially the composition of a peridotite, and are quite unlike the rocks which make up the great mass of the lithosphere. If, therefore, the earth was formed by an aggregation of meteors, as some writers have supposed, their average character was probably not that of the meteorites known to-day. Quartz and feldspars are the most abundant minerals of the lithosphere as we know it, but are almost wanting in the meteorites. A nucleus of iron with a stony crust could hardly be formed by any clashing together of innumerable meteoritic bodies; if the earth is analogous to them it can only be as an independent, individual meteorite of quite dissimilar composition. 2 1 Am. Jour. Sci., 4th ser., vol. 27, 1909, p. 469. See also W. A. Wahl, Zeitschr. anorg. Chemie, vol. 69, 1910, p. 52, and O. C. Farrington, Field Columbian Museum Publication 151, 1911. 2 For a critical discussion of hypotheses relative to the nature and temperature of the centrosphere see H. Thiene, Temperatur und Zustand des Erdinnern, Jena, 1907. Thiene gives many references to litera- ture. See also E . H. L. Schwarz, South African Jour. Sci., April, 1910. Schwarz advocates a solid nucleus of the earth and assigns to it a low temperature. CHAPTER II. THE ATMOSPHERE. COMPOSITION OF THE ATMOSPHERE. The outer gaseous envelope of our globe — the atmosphere — is commonly regarded as rather simple in its constitution, and indeed so it is, in comparison with the complexity of the ocean and the solid rocks beneath. Broadly considered, it consists of three chief con- stituents — namely, oxygen, nitrogen, and argon — commingled with various other substances in relatively small amounts, which may be classed, with some exceptions, as impurities. The three essential elements of air are mixed, but not combined; and they vary but little in their proportions. They constitute what may be called normal or average air. I am indebted to Sir William Ramsay for the following percentage estimate of their relative quantities. The principal constituents of the atmosphere. By weight. By volume. Oxygen 23. 024 20. 941 Nitrogen 75. 539 78. 122 Argon 1. 437 .937 100. 000 100. 000 With the argon occur certain rare gases whose proportions Ramsay estimates as follows : 1 Krypton. Xenon... Helium . . Neon Per cent by volume. 0.028 005 0004 00123 These gases, with argon, are absolutely inert; and as they seem to have little geological significance they demand no further considera- tion here. Helium, as the end product of radioactive changes, will demand some attention later. In addition to the elements enumerated above, ordinary air con- tains, in varying quantities, aqueous vapor, hydrogen dioxide, ozone, carbon dioxide, ammonia and other compounds of nitrogen, some- times sulphur, traces of hydrogen, organic matter, and suspended solids; and among these substances some of the most active agents 1 Proc. Roy. Soc., vol. 80A, 1908, p. 599. See also papers by G. Claude, Compt. Rend., vol. 148, 1909, p. 1454, and H. E. Watson, Jour. Chem. Soc., vol. 97, 1910, p. 810. A. Wegener (Zeitschr. anorg. Cbemie, vol. 75, 1912, p . 107) gives an estimate of the composition of the atmosphere, including its minor constituents. 41 42 THE DATA OF GEOCHEMISTRY. in producing geological changes are found. It will be advantageous to consider them separately and somewhat in detail; and in so doing we shall see that they all form part of a great system of circulation in which the atmosphere is adding matter to the solid globe and receiving matter from it in return. Between these gains and losses no balance can be struck, and yet certain tendencies appear to be distinctly manifested. In a roughly approximate way it is often said that air consists of four-fifths nitrogen and one-fifth oxygen, and this is nearly true. The proportions of the two gases are almost constant, but not abso- lutely so; for the innumerable analyses of air reveal variations larger than can be ascribed to experimental errors. A few of the better determinations are given in the subjoined table, stated in percentages by volume of oxygen. They refer, of course, to air dried and freed from all extraneous substances. Determinations of oxygen in air, in percentage by volume. Analyst. Locality of samples. Number of analyses. Minimum. Maximum. Mean. V. Regnault® Paris 100 20. 913 20. 999 20. 960 R. W. Bunsen® Heidelberg 28 20. 840 20. 970 20. 924 R. Angus Smith®. . . Manchester 32 20. 78 21. 02 20. 943 Do Mountains of Scot- land. 34 20. 80 21. 18 20. 970 U. Kreusler & . . Near Bonn 45 20. 901 20. 939 20. 922 W. Hempel c Dresden 46 20. 877 20. 971 20. 930 Do.® Tromsoe 41 21. 00 20. 92 Do Para 28 20. 86 20. 89 A. Muntz and E. Cape Horn 20 20. 72 20. 97 20. 864 Aubin.e E. W. Morley/ F. G. Benedict 9 Cleveland, Ohio Boston 45 212 20. 90 20. 95 20. 933 20. 952 a See R. Angus Smith’s excellent book Air and rain, London, 1872. This work contains hundreds of other analyses. b Ber. Deutsch. chem. Gesell., vol. 20, 1887, p. 991. c Idem, vol. 18, 1885, p. 1800. d Idem, vol. 20, 1887, p. 1864. e Compt. Rend., vol. 102, 1886, p. 422. / Cited by Hempel in Ber. Deutsch. chem. Gesell., vol. 20, 1887, p. 1864. g Carnegie Inst. Washington Publication No. 166, 1912. Benedict gives a very complete summary of earlier investigations. Some of these variations are doubtless due to different methods of determination, but others can not be so interpreted. Hempel, comparing his analyses of air from Tromsoe, Norway, and Para, Brazil, infers that the atmosphere is slightly richer in oxygen near the poles than at the equator, an inference that would seem to need additional data before it can be regarded as established. The most significant variation of all, however, has been pointed out by E. W. Morley . 1 As oxygen is heavier than nitrogen, it has been supposed 1 Am. Jour. Sci., 3d sor., vol. 18, 1879, p. 168; vol. 22, 1881, p. 417. For the distribution of the different gases in the atmosphere according to elevation, see W. J. Humphreys, Bull. Mount Weather Observatory, vol. 2, 1900, p. 68. THE ATMOSPHERE. 43 that the upper regions of the atmosphere should show a small defi- ciency in oxygen, as compared with air from lower levels; although analyses of samples collected on mountain tops and from balloons have not borne out this suspicion. It is also supposed that severe depressions of temperature, the so-called “cold waves,” are con- nected with descents of air from very great elevations. Morley’s analyses, conducted daily from January, 1880, to April, 1881, at Hudson, Ohio, sustain this belief. Every cold wave was attended by a deficiency of oxygen, the determinations, by volume, ranging from 20.867 to 21.006 per cent, a difference far greater than could be attributed to errors of measurement. Air taken at the surface of the earth seems to show a very small concentration of the denser gas, oxygen. By electrical discharges in the atmosphere some oxygen is probably converted into its allotropic modification, ozone, although this point has been questioned. Hydrogen dioxide is formed in the same way, and also oxides of nitrogen, and between these substances, in minute traces, it is not easy to discriminate. They all act upon the usual reagent, iodized starch paper, and therefore the identification of ozone remains somewhat uncertain, at least so far as ordinary chemi- cal tests have gone. It is known, however, that the ultra-violet rays in the solar radiations so act upon cold dry oxygen as to convert part of it into ozone. This apparently takes place in the upper, drier, and rarefied strata of the atmosphere, as shown by absorption bands in the solar spectrum. 1 Both ozone and hydrogen dioxide are powerful oxidizing agents, and either or both of them play some part in transforming organic matter suspended in the air into carbon dioxide, water, and probably ammonium nitrate; but the magnitude of the changes thus brought about can not be estimated with any degree of definiteness. Ozone is also a powerful absorbent of solar radiations, and may possibly exert some influence in modifying terrestrial climates. Its generation by auroral discharges as well as by ultra-violet rays is considered in this connection by Humphreys. According to H. N. Holmes 2 the proportion of ozone in the atmos- phere is greater in winter than in summer. Wherever animals breathe or fire burns oxygen is being withdrawn from the air and locked up in compounds. By growing plants under the influence of sunlight, one of these compounds, carbon dioxide, is decomposed and oxygen is liberated; but the losses exceed the gains. So also, when the weathering of a rock involves the change of fer- rous into ferric compounds oxygen is absorbed, and only a portion of 1 See W. J. Humphreys, Astrophys. Jour., vol. 32, 1910, p.97, and authorities cited by him. Also Henriet and Bonyssy, Compt. Rend., vol. 147, 1908, p. 977. According to W. Hayhurst and J. N. Pring (Jour. Chem. Soc., vol. 97, 1910, p. 868) the ozone in the atmosphere amounts to less than one part in four thousand millions. In another paper (Proc. Roy. Soc., vol. 90A, p. 204) Pring finds that air from high altitudes contains more ozone than air from low levels. 2 Am. Chem. Jour., vol. 47, p. 497, 1912. 44 THE DATA OF GEOCHEMISTRY. it is ever again released. The atmosphere then is slowly being depleted of its oxygen, but so slowly that no chemical test is ever likely to detect the change. The nitrogen of the atmosphere varies reciprocally with the oxy- gen, the one gaining relatively as the other loses. But here again special variations need to be considered. By electrical discharges, as we have already seen, oxides of nitrogen are produced, yielding with the moisture of the air nitric and nitrous acids. Through the agency of microbes certain plants withdraw nitrogen directly from the air and thus remove it temporarily from atmospheric circulation. By the decay or combustion of organic matter some of this nitrogen is returned, partly in the free state and partly in gaseous combina- tions. The significance of these changes will be more clearly seen when we consider the subject of rain. It is enough to note here that all the nitrogen of organic matter came originally from the atmos- phere, and that at the same time a larger quantity of oxygen was also removed. The relative proportions of the two gases are evidently undergoing continuous modification. According to Armand Gautier 1 free hydrogen is present in the atmosphere, together with other combustible gases. Air collected at the Roches-Douvres lighthouse, off the coast of Brittany, yielded 1.21 milligrams of hydrogen in 100 liters. Air from the streets of Paris was found to contain the following substances, in cubic centi- meters per 100 liters: Free hydrogen 19. 4 Methane 12. 1 Benzene and its homologues 1.7 Carbonic oxide, with traces of olefines and acetylenes 2 In short, air, according to Gautier, contains by volume about 1 part in 5,000 of free hydrogen, although Rayleigh’s 2 experiments on the same subject would indicate that this estimate is at least six times too large. It is known, however, that hydrogen is emitted by vol- canoes in considerable quantities, and Gautier has extracted the gas from granite and other rocks. One hundred grams of granite gave him 134.61 cubic centimeters of hydrogen with other gases, and from this fact important inferences can be drawn. At the proper point, farther on, this subject will he discussed more fully. As for the hydrocarbons, their chief source is doubtless to be found in the decomposition of organic matter, methane or marsh gas in particular being clearly recognized among the exhalations from swamps. 1 Annales chim. phys., 7th ser., vol. 22, 1901, p. 5. 2 Philos. Mag., 6th ser., vol. 3, 1902, p. 416. See also a criticism by A. Leduc, Compt. Rend., vol. 135, 1902, p» 860; and replies to Rayleigh and Leduc by Gautier, idem, vol. 135, p. 1025; vol. 136, p. 21. Also a paper by G. D. Liveing and J. Dewar, Proc. Roy. Soc., vol. 67, 1900, p. 468. G. Claude (Compt. Rend., vol. 148, 1909, p. 1454) found less than one part per million of hydrogen in air. THE ATMOSPHERE. 45 According to H. Henriet,® formaldehyde exists in the atmosphere in quantities ranging from 2 to 6 grams in 100 cubic meters. Bodies of this class are impurities in the atmosphere, and should not be reckoned among its normal constituents. Sulphur compounds, which are also contaminations of the atmos- phere, occur in air in variable quantities. Hydrogen sulphide is a product of putrefaction, but it is also given off by volcanoes, together with sulphur dioxide. The latter substance is also pro- duced by the combustion of coal, and is therefore abundant in the air of manufacturing districts. At Lille, for example, A. Ladureau 6 found 1.8 cubic centimeters of S0 2 in a cubic meter of air. It under- goes rapid oxidation in presence of moisture, being converted into sulphuric acid, and that compound, either free or represented by ammonium sulphate, is brought back to the surface of the earth by rain. In experiments running over five years at Bothams ted, England, R. Warington c found that the equivalent of 17.26 pounds of S0 3 was annually poured upon each acre of land at that station. Quantities of this order can not be ignored in any study of chemical erosion. One of the most constant and most important of the accessory constituents of air is carbon dioxide. It is normally present to the extent of about 3 volumes in 10,000, with moderate variations above and below that figure. In towns its proportion is higher; in the open country it is slightly lower; but the agitation of winds and atmos- pheric currents prevent its excessive accumulation at any point. Only a few illustrations of its quantity need be given here/ abnormal extremes being avoided. Determinations of carbon dioxide in air. Analyst. Locality. Number of de- terminations. CO 2 (volumes per 10,000 of air). J. Heiset e Paris 3. 027 Do Near Dieppe 92 2. 942 T. C. Van Niiys and B. F. Bloomington, Ind 18 2.816 Adams./ A. Petermann and J. Graftiau 9. . Gembloux, Belgium 525 2. 94 E. A. Letts and E. F. Blake h Belfast 46 2. 91 a Compt. Rend., vol. 138, 1904, pp. 203, 1272. b Annales chim. phys., 5th ser., vol. 29, 1883, p. 427. c Jour. Chem. Soc., vol. 51, 1887, p. 500. A later figure gives 17.41 pounds. See N. H. J. Miller, Jour. Agr. Sci., vol. 1, 1905, p. 292. Miller cites data from Catania, Sicily, giving 20.89 pounds. G. Gray (Rept. Australasian Assoc. Adv. Sci., vol. 1, 1888, p. 138) found 15.2 pounds per acre per annum in 4 \ years’ obser- vations at Lincoln, New Zealand. d Very elaborate data are given in R. Angus Smith’s Air and rain, to which reference has already been made. See also the excellent paper by E. A. Letts and R. F. Blake, Sci. Proc. Roy. Dublin Soc., vol. 9, pt. 2, 1900, pp. 107-270. The latter memoir contains a summary of all the determinations previously made, with a very thorough bibliography of the subject. e Compt. Rend., vol. 88, 1879, p. 1007. / Am. Chem. Jour., vol. 9, 1887, p. 64. g Cited by Letts and Blake. h Sci. Proc. Roy. Dublin Soc., vol. 9, pt. 2, 1900, pp. 107-270. 46 THE DATA OF GEOCHEMISTRY. At 3 parts in 10,000 the carbon dioxide in the atmosphere amounts to about 2,200,000,000,000 tons, equivalent to 600,000,000,000 tons of carbon. 1 Thousands of other determinations having meteorological, sanitary, or agricultural problems in view are recorded, but their discussion does not fall within the scope of this work. 2 That in general terms the proportion of carbon dioxide in the atmosphere is very nearly uniform is the point that concerns us now. How is this apparent constancy maintained ? From several sources carbon dioxide is being added to the air. The combustion of fuels, the respiration of animals, and the decay of organic matter all generate this gas. From mineral springs and vol- canoes it is evolved in enormous quantities. According to J. B. Boussingault, 3 Cotopaxi alone emits more carbon dioxide annually than is generated by life and combustion in a city like Paris, which in 1844 threw into the air daily almost 3,000,000 cubic meters of the gas. Since that time the population of Paris has more than doubled, and the estimate must be correspondingly increased. The annual con- sumption of coal, estimated by A. Krogh 4 at 700,000,000 tons in 1902, adds yearly to the atmosphere about one-thousandth of its present content in carbon dioxide. In a thousand years, then, if the rate were constant and no disturbing factors interfered, the amount of C0 2 in the atmosphere would be doubled. If we take into account the combustion of fuels other than coal and the large additions to the atmosphere from the sources previously mentioned, the result becomes still more startling. Were there no counterbalancing of this increase in atmospheric carbon, animal life would soon become impossible upon our planet. Figures like those given above convey some faint notion of the magnitude of the chemical processes now under con- sideration. On the other side of the account two large factors are to be con- sidered — first, the decomposition of carbon dioxide by plants, with liberation of oxygen ; and, second, the consumption of carbon dioxide in the weathering of rocks. To neither of these factors can any precise valuation be given, although various writers have attempted to estimate their magnitude. E. H. Cook, 5 * * * * * for instance, from very uncertain data, computes that leaf action alone more than compen- 1 A. Krogh (Meddelelser om Groenland, vol. 26, 1904, p. 419) estimates the total C0 2 in the atmosphere at 2.4X10 12 tons. Van Hise (Mon. U. S. Geol. Survey, vol. 47, 1904, p. 964) and Dittmar (Challenger Report, vol. 1, pt. 2, p. 954) gives figures of the same order. Chamberlin (Jour. Geology, vol. 7, 1899, p. 682) makes a somewhat higher estimate. 2 For example, E. L. Moss (Proc. Roy. Dublin Soc., 2d ser., vol. 2, 1878, p. 34) found that Arctic air is richer in carbon dioxide than the air of England. In air from Greenland A. Krogh (Meddelelser om Groen- land, vol. 26, 1904, p. 409) found the proportion of carbon dioxide to vary from 2.5 up to 7 parts in 10,000. The proportion determined by R. Legendre (Compt. Rend., vol. 143, 1906, p. 526) in ocean air was 3.35 in 10,000. a Annales chim. phys., 3d ser., vol. 10, 1844, p. 456. * Loc. cit. The present consumption of coal exceeds 1,000,000,000 tons. Krogh ’s figures should be corre- spondingly modified. e Philos. Mag., 5th ser., vol. 14, 1882, p. 387. THE ATMOSPHERE. 47 sates for the production of carbon dioxide, and that without such compensation the quantity present in the air would double in about 100 years. Some of the carbon dioxide thus absorbed is annually returned to the atmosphere by the autumnal decay of leaves, but part of it is permanently withdrawn. T. Sterry Hunt 1 illustrates the effect of weathering by the state- ment that the production from orthoclase of a layer of kaolin, 500 meters thick and completely enveloping the globe, would consume 21 times the amount of carbon dioxide now present in the atmos- phere. He also computes that a similar shell of pure carbon, of density 1.25 and 0.7 meter in thickness, would require for its com- bustion all the oxygen of the air. Such estimates may have slight numerical value, but they serve to show how vast and how im- portant the processes under consideration really are. The carbon of the coal measures and of the sedimentary rocks has all been drawn, directly or indirectly, from the atmosphere. Soluble carbon- ates, produced by weathering, are washed into the ocean, and are there transformed into sediments, into shells, or into coral reefs; but the atmosphere was the source from which all, or nearly all, of the carbon thus stored away was taken. The carbon of the sedi- mentary rocks, as computed with the aid of data given in the pre- ceding chapter, is about 30,000 times as much as is now contained in the atmosphere. T. C. Chamberlin 2 estimates that the amount of carbon dioxide annually withdrawn from the atmosphere is 1,620,000,000 tons, but the method by which this figure was obtained is not clearly stated. In calculations of this sort there is a certain fascination, hut their chief merit seems to lie in their suggestiveness. THE RELATIONS OF CARBON DIOXIDE TO CLIMATE. From a geological standpoint the carbon dioxide of the air has a twofold significance — first, as a weathering agent, and second, as a regulator of climate. The subject of weathering will receive due consideration later; but the climatic value of atmospheric carbon may properly be mentioned now. Both carbon dioxide and aqueous vapor serve as selective absorbents for the solar rays, and, by blanket- ing the earth, they help to avert excessive changes of temperature. On the physical side, and as regards carbon dioxide, this question has been discussed by S. Arrhenius, 3 who argues that if the quantity of the gas in the atmosphere were increased about threefold, the mean temperature of the Arctic regions would rise 8° or 9°. A corresponding loss of carbon dioxide would lead to a lowering of temperature; and in variations of this kind we may find an explana- tion of the alterations of climate which have undoubtedly occurred. The glacial period, for example, may have been due to a loss of carbon 1 Am. Jour. Sci., 3d ser., vol. 19, 1880, p. 349. 2 Jour. Geology, vol. 7, 1899, p. G82. 3 Philos. Mag., 5th ser., vol. 41, 189G, p. 237. Annalen d. Physik, 4th ser., vol. 4, 1901, p. G90. 48 THE DATA OF GEOCHEMISTRY. dioxide from the atmosphere. To account for such gains and losses, Arrhenius cites with great fullness the work of A. G. Hogbom, who regards volcanoes as the chief source of supply. Just as indi- vidual volcanoes vary in activity from quietude to violence, so the volcanic activity of the globe has varied from time to time. During periods of great energy the carbon dioxide of the air would be abundant; at other times its quantity would be smaller. Hogbom estimates that the total carbon of the atmosphere would form a layer 1 millimeter thick, enveloping the entire globe. The quantity of carbon in living matter he regards as being of the same order, neither many fold greater nor many fold less. The combustion of coal he reckons as about balancing the losses of the atmosphere by weathering; and in this way he reaches his conclusion that vol- canic action is the important factor of the problem. This theory of Arrhenius has been, however, a subject of much controversy. It was strongly endorsed by F. Freeh, 1 who has attempted by means of it to account for glacial periods. E. Kayser, 2 on the other hand, has attempted to prove that the views of Arrhenius are untenable, on the ground of K. J. Angstrom’s 3 physical researches. Angstrom has shown that carbon dioxide in the atmosphere can not possibly absorb more than 16 per cent of the terrestrial radiations, and that variations in its amount are of very small effect. Further- more, C. G. Abbot and F. E. Fowle 4 have shown that aqueous vapor is present in the atmosphere in quantities so large as to make the climatic significance of carbon dioxide negligible. The principal absorbent of terrestrial radiations is the vapor of water. Whether the theory of Arrhenius is in harmony with the facts of historical geology — that is, whether periods of volcanic activity have coincided with warmer climates, and a slackening of activity with lowering of temperature — is also in dispute. The controversy is not yet ended. 5 One other suggested regulative agency remains to be mentioned. The ocean is a vast reservoir of carbon dioxide, which is partly in solution and partly combined. Between the surface of the sea and the atmosphere there is a continual interchange, each one sometimes losing and sometimes gaining gas. Upon this fact a theory of climatic variations has been founded, and in another chapter, upon the ocean, it will be stated and discussed. 1 Zeitschr. Gesell. Erdkunde, Berlin, vol. 37, 1902, pp. 611, 671; idem, 1906, p. 533. Neues Jahrb., 1908, pt. 2, p. 74. 2 Centralbl. Min., Geol. u. Pal., 1908, p. 553; 1909, p. 660. Rejoinder by Arrhenius, idem, 1909, p. 481. Later papers by Arrhenius and Kayser are in the same journal for 1913, pp. 582, 764. 3 Annalen d. Physik, 4th ser., vol. 3, 1900, p. 720; vol. 6, 1901, p. 163. Angstrom himself criticizes Arr- henius. 4 Annals Astrophys. Observ., vol. 2, 1908, pp. 172, 175. 5 On the geologic side of the question see Kayser, loc. cit., and Lehrbuch der allgemeinen Geologie, 3d ed., 1909, pp. 81-83. Also E. Koken, Neues Jahrb., Fest Band, 1907, p. 530, and E. Philippi , Centralbl. Min., Geol. u. Pal., 1908, p. 360. The papers referred to contain many other references to literature. On the influence of volcanic dust on climate, see W. J. Humphreys, Jour. Washington Acad. Sci., vol. 3, p. 365, 1913. THE ATMOSPHERE. 49 RAINFALL. Among all the constituents of the atmosphere aqueous vapor is the most variable in amount and the most important geologically. It is not merely a solvent and disintegrator of rocks, but it is also a carrier, distributing other substances and making them more active. To the circulation of atmospheric moisture we owe our rivers, and through them erosion is effected. The process of erosion is partly chemical and partly mechanical, and the two modes of action reinforce each other. By flowing streams the rocks are ground to sand, and so new surfaces are exposed to chemical attack. On the other hand, chemical solution weakens the rocks and renders them easier to remove mechan- ically. As water evaporates from the surface of the sea, it lifts, by inclusion in vapory vesicles, great quantities of saline matter, which are afterward deposited by rainfall upon the land. It is through the agency of rain or snow that the atmosphere produces its greatest geological effects; but the chemical side of its activity is all that con- cerns us now. Aqueous vapor dissolves and concentrates the other ingredients of air and brings them to the ground in rain. In one sense oxygen is the most active of the atmospheric gases, but without the aid of moisture its effectiveness is small. Perfectly dry oxygen is comparatively inert; for example, phosphorus burns in it slowly and without flame, but the merest trace of water gives the gas its usual activity. 1 More than this trace is always present in the air, and when it condenses to rain it dissolves oxygen, nitrogen, carbon dioxide, and other gases. These substances differ in solubility, and therefore dissolved air contains them in abnormal proportions. In air extracted from rain water, Humboldt and Gay-Lussac found 31 per cent of oxygen. R. W. Bunsen, 2 who examined air from rain water at different temperatures, gives the following table to illustrate its composition by volume: Composition of dissolved air at different temperatures. 0° 5° 10° 15° 20° n 2 63. 20 63. 35 63. 49 63. 62 63. 69 0 2 33. 88 33. 97 34. 05 34. 12 34. 17 co 2 2. 92 2. 68 2. 46 2.26 2. 14 100. 00 100. 00 100. 00 100. 00 100.00 In air from sea water O. Pettersson and K. Sonden 3 found nearly 34 per cent of oxygen. In dissolved air, then, and especially in rain, oxygen is concentrated, and in that way its effectiveness is increased. 1 See H. Brereton Baker, Proc. Roy. Soe., vol. 45, 1888, p. 1. s Liebig’s Annalen, vol. 93, 1855, p. 48. See also M. Baumert, idem, vol. 88, 1853, p. 17, for evidence of the same order. * Ber. Deutsch. chem. Gesell., vol. 22, 1889, p. 1439. 97270°— Bull. GIG— 10 4 50 THE DATA OF GEOCHEMISTRY, The same is true of carbon dioxide. Rain brings it to the surface of the earth, where its eroding power comes into play. As a carrier of ammonia, nitric acid, sulphuric acid, and chlorine, rain water performs a function of the highest significance to agricul- ture, but whose geological importance has not been generally recog- nized. Rain and snow collect these impurities from the atmosphere, in quantities which vary with local conditions, and redistribute them upon the soil. Many analyses of rain water have therefore been made, not only at agricultural experiment stations, but also for sani- tary purposes, and a few of the results obtained are given below.® Figures for sulphuric acid have already been cited. The values given are stated in pounds per acre per annum brought to the surface of the earth at the several stations named. For nitrogen compounds the data are as follows: Nitrogen brought to the surface of the earth by rain. [Pounds per acre per annum.] Locality. Nitrogen. Remarks. Ammoniacal. Nitric. Total. Rothamsted, England & 2. 406 5 years’ average. 1888-1901. Rothamsted, England c 2. 71 1. 13 3. 84 N ear Paris ^ 8. 93 11 years’ average. Caracas, Venezuela e .516 Gembloux, Belgium / 9. 20 2\ years’ average. 5 years’ average. 20 years’ average. 3 years’ average. 3 years’ average. 3 years’ average. 4 J years’ average. 11 months’ aver- Barbados 9 1. 009 2. 443 3. 452 British Guiana A 1. 006 1. 886 3. 541 Kansas * 2. 63 1. 06 3. 69 Utah j 5. 06 .356 5. 42 Mississippi & 3. 636 New Zealand J 2. 08 Iceland * . 802 . 263 1. 065 Hebrideo m .311 .289 . 600 age. 11 month’s aver- age. a For the older data see R. Angus Smith, Air and rain, London, 1872. For nitrogen and chlorides in rain and snow at Mount Vernon, Iowa, see G. II. Wiesner. Chem. News, vol. 103, 1914, p. 85. See also W. J. Knox, for data from the same locality, Chem. News, vcl. Ill, 1915, p. 61. F. T. Shutt (Trans. Roy. Soc. Canada, 3d ser., vol. 8, 1914, p. 83) gives data for nitrogen in rain and snow during seven years’ observations at Ottawa. The observations cover 14 weeks only. The annual report of the Rothamsted Station, England, for 1913. contains additional data on nitrogen. b R. Warington, Jour. Chem. Soc., vol. 51, 1S87, p. 500. c N. II. J. Miller, Jour. Agr. Sci., vol. 1, 1905, p. 2S3. See also R. Warington, Jour. Chem. Soc., vol. 35, 1889, p. 537, for earlier figures. Miller gives a table for 35 localities, and also an excellent bibliography of the entire subject of nitrogen, sulphuric acid, and chlorine in rain. d Albert Levy, Jour. Chem. Soc., vol. 56, 1889, p. 299. (Abstract.) 10.01 kilos per hectare. e A. Muntz and V. Marcano, Compt. Rend., vol. 108, 1889, p. 10C2. / A. Petermann and J. Graftiau, Jour. Chem. Soc., vol. 04, 1893, abst. ii, p. 548. 10.31 kilos per hectare. g J. B. Harrison and J. Williams, Jour. Am. Chem. Soc., vol. 19, 1897, p. 1. A J. B. Harrison, Rept. Dept. Sci. and Agr., British Guiana, 1909-10. For earlier figures see preceding reference. i G. H. Failyer and C. M. Breese, Second Ann. Rept. Exper. Sta., Kansas Agr. Coll., 1889. j R. W. Erwin, Fourth Ann. Rept. Utah Agr. Coll. Exper. Sta., 1893. k Hutchinson, Tenth Ann. Rept. Mississippi Agr. and Mech. Coll. Exper. Sta., 1897. See also Eighth Ann. Rept. i G. Gray, Rept. Australasian Assoc. Adv. Sci., vol. 1, 1888, p. 138. The figures include some albumi- noid nitrogen. m N. H. J. Miller, Jour. Chem. Soc., vol. 106, i, 1914, p. 128, Abstract. THE ATMOSPHERE. 51 In most cases ammonia is in excess over nitric acid; but in the Tropics the reverse seems to be true. The substance actually brought to earth, then, is in great part ammonium nitrate, but the conditions are modified when hydrochloric or sulphuric acid happens to be present in the air. A large part of the combined nitrogen has of course been added to the atmosphere by organic decomposition at the surface of the earth; but some of it is due, as we have already seen, to electrical discharges during thunderstorms. The geological sig- nificance of free acids in rain is obvious, for it means an increase in the eroding power of water. Furthermore, in this circulation of nitrogen between the ground and the air, the ground gains more than it loses. All of the nitrogen thus fixed in combination is not released again to the atmosphere; only a part so returns . 1 The figures for atmospheric chlorine are even more surprising; but they represent in general salt raised by vapor from the ocean. Where chemical industries are carried on, free hydrochloric acid may enter the air, and some hydrochloric acid is also evolved from volca- noes; but these are minor factors of little more than local signifi- cance. Chlorine is abundant in the air only near the sea, and its proportion rapidly diminishes as we recede from the coast. This is clearly shown by the “ chlorine map” of Massachusetts , 2 and by several later documents of the same kind, in which the “ normal chlorine” of the potable waters is indicated by isochlors that follow the contour of the shore. Near the ocean the waters are rich in chlorides, which diminish rapidly as we follow the streams inland. The amount of salt precipitated by rain upon the land is by no means inconsiderable. For quantitative data a few examples must suffice, stated in the same way as for nitrogen. 1 T. Schloesing (Contributions a 1’ etude de la chimie agricole, 1888, p. 55) estimates the average ammonia in the atmosphere at 0.02 milligram per cubic meter. This amounts to 1,600 grams over every hectare of the earth’s surface. On nitrates in the atmosphere see A. Muntz and E. Laine, Compt. Rend., vol. 152, 1911, p. 167. J. Hirschwald (Die Priifung der natiirlichen Bausteine, Berlin, 1908, p. 5) gives many data for ammonia and nitrates in the air. 2 See T. M. Drown, in Rept. Massachusetts State Board of Health, etc., vol. 1, December, 1889. Mrs. Ellen S. Richards, who was associated with Drown in this investigation, has since published, jointly with A. T. Hopkins, a similar map of Jamaica (Tech. Quart., vol. 11, 1898, p. 227). For a chlorine map of Long Island, see G. C. Whipple and D. D. Jackson, Tech. Quart., vol. 13, 1900, p. 145. One of Connecticut appears in the report of the State board of health for 1895. For a general chlorine map of New York and New England, see Jackson, Water-Supply Paper U. S. Geol. Survey No. 144, 1905. 52 THE DATA OF GEOCHEMISTRY. Chlorides brought to the surface of the earth by rain. [Pounds per acre per annum.] Locality. Chlorine. Sodium chloride. Remarks. Cirencester, England® 36. 10 26 years’ average. Rothamsted, England b Rothamsted, England c 14. 40 14. 87 24. 00 Perugia, Italy d 37. 95 In 1887. Ceylon 6 180. 63 Calcutta 6 32. 87 Madras 6 36. 27 Odessa, Russia/ 17. 00 Barbados 9 116. 98 5 years’ average. 20 years’ average. 4| years’ average. British Guiana b 129. 24 195. 00 New Zealand* 61. 20 a E. Kinch, Jour. Chem. Soc., vol. 77, 1900, p. 1271. b R. Warington, idem, vol. 51, 1887, p. 500. cN. H. J. Miller, Jour. Agr. Sci., vol. 1, 1905. p. 292. Miller gives figures for several other localities. d G. Bellucci, Jour. Chem. Soc., abstract, vol. 56, 1899, p. 299. 42.531 kilos per hectare. « Cited by Miller, loc. cit. / J. Pirovaroff, Ann. geol. min. Russie, vol. 9, 1908, p. 274. 19 kilos per hectare. g J. B. Harrison and J. Williams, Jour. Am. t hem. Soc., vol. 19, 1897, p. 1. h J. B. Harrison, Rept. Dept. Sci. and Agr., British Guiana, 1909-10. For earlier figures see preceding reference. i G. Gray, Rept. Australian Assoc. Adv. Sci., vol. 1, 1888, p. 138. Furthermore, we have the older researches of Pierre, 1 whose anal- yses were made in 1851 at Caen, in Normandy, where each hectare of soil was found to receive annually, in rain, the following impurities: Kilograms. NaCl 37.5 KC1 8. 2 MgCl 2 2. 5 CaCl 2 1. 8 Kilograms. Na 2 S0 4 8.4 K 2 S0 4 ..... 8. 0 CaS0 4 6. 2 MgS0 4 5.9 These citations are enough to show the great geological impor- tance of rainfall, over and above its ordinary mechanical effects, and its value as a solvent after it enters the groimd. The atmospheric circulation of salt has received much attention, and F. Posepny, 2 as long ago as 1877, attempted to show that the sodium chloride of inland waters was derived largely from this source. Of late years the same idea has been strongly urged by W. Ackroyd, 3 who has gone so far as to attribute the salinity of the Dead Sea to chlorides brought by winds from the Mediterranean. Furthermore, A. Muntz 4 has pointed out that without this circu- 1 See R. Angus Smith, Air and rain, 1872, pp. 223-232. Pierre also cites valuable data obtained by Barral, Bineau, Liebig, Boussingault, and others. See also A. Bobierre, Compt. Rend., vol. 58, 1864, p. 755, for the composition of rain water collected at Nantes in 1863. The average sodium chloride amounted to 14.09 grams per cubic meter. 2 Sitzungsb. K. Akad. Wiss. Wien, vol. 76, Abth. 1, 1877, p. 179. See also a discussion of this memoir by E. Tietze, Jahrb. K.*k. geol. Reichsanstalt, vol. 27, 1877, p. 341. In a recent discussion of this subject E. Dubois (Arch. Mus6e Teyler, 2d ser., vol. 10, 1907, p. 441) has estimated the amount of atmospheric salt annually precipitated in rainfall on two provinces of Holland as about 6,000,000 kilograms. 3 Geol. Mag., 4th ser., vol. 8, 1900, p. 445. Proc. Yorkshire Geol. and Polytech. Soc., vol. 14, p. 408. Chem. News, January 8, 1904. * Compt. Rend., vol. 112, 1891, p. 449. THE ATMOSPHERE. 53 lation of salt, and its replenishment of the land, the latter would soon be drained of its chlorides, and living beings would suffer from the loss. These writers probably overemphasize the importance of “cyclic salts,” as they have been called, but their arguments are enough to show that the phenomena under consideration are by no means insignificant. Wind-borne salt plays a distinct part in the economy of nature; but its influence is yet to be studied in definite, quantitative terms. An exception to this statement is furnished by the Sambhar Salt Lake in India, which will be considered in detail in another chapter. Apart from its function in carrying soluble salts, the atmosphere performs a great work in mechanically transporting other solids. Its effectiveness as a carrier of dust is well understood; dust from the explosion of Krakatoa was borne twice around the globe, but such processes bear indirectly upon chemistry. In desert regions the sand- storms help to disintegrate the rocks, and so to render them more susceptible to chemical change. Dust, also, whether cosmic or ter- restrial, furnishes the nuclei around which drops of rain are formed, and so reinforces the activity of atmospheric moisture . 1 THE PRIMITIVE ATMOSPHERE. Although the main purpose of this treatise is to assemble and classify data, rather than to discuss speculations, a few words as to the origin of our atmosphere may not be out of place. Upon this subject much has been written, especially in recent years; but none of the widely variant theories so far advanced can be regarded as conclusive. The problem, indeed, is one of cosmology, and chemical data supply only a single line of attack. Physical, astronomical, mathematical, and geological evidence must be brought to bear upon the question before anything like an intelligent conclusion can be reached. Even then, with every precaution taken, we can hardly be sure that our fundamental premises are sound. One phase of the discussion, to which I have already referred, relates to the constancy or variability of the atmosphere. The accu- mulations of carbon in the lithosphere, such as the coal measures, the limestones, and the like, have led some geologists to assume that the atmosphere at some former time was vastly richer in carbonic acid than it is now; but the fossil records of life suggest that the differences could not have been extreme. With a large excess of car- bon dioxide the existence of air-breathing animals would be impos- sible. Only anaerobic organisms could live. It is clear that the stored carbon of the sedimentary rocks was once largely in the atmos- phere, but was it ever all present there at any one time ? 1 See J. Aitken, Proc. Roy. Soc. Edinburgh, vol. 17, 1890, p. 193. An interesting lecture by A. Ditte (Revue scient., 5th ser., vol. 2, 1904, p. 709), on metals in the atmosphere, is well worthy of notice. It deals with dust, meteoric matter, cyclic salts, ammonium compounds, etc. 54 THE DATA OF GEOCHEMISTRY. Such a supposition is improbable. The known carbon of the lithosphere, if converted into carbon dioxide, would yield nearly 25 times the present mass of the entire atmosphere, and the atmospheric pressure at the surface of the earth would be enormously increased. 1 It is more likely that carbon dioxide has been added to the atmosphere by volcanic agency, in some such manner as this: Primitive carbon, like the graphite found in meteorites, at temperatures no greater than that of molten lava, reduced the magnetite of igneous rocks to metallic iron, such as is found in many basalts, and was itself thereby oxidized. Then, discharged into the atmosphere as dioxide, it became subject to the familiar reactions which restored it to the lithosphere as coal or limestone. In order to account for the observed phenomena, several essentially distinct hypotheses have been proposed. T. Sterry Hunt, 2 for example, argued in favor of a cosmical atmosphere, pervading all space, from which a steady supply of carbon dioxide has been drawn. This theory, which was also favored by Alexander Winchell, 3 postu- lates a universal, exhaustless reservoir of carbon, which should be able to satisfy all demands. But what evidence have we that such an atmosphere exists ? S. Meunier, 4 criticizing Hunt, points out that some planets have excessive and others deficient atmospheres, and that a cosmic uni- formity is therefore improbable. Meunier prefers the volcanic theory, for which we have at least some basis of fact. We know that gases are emitted from volcanoes, even though there is no certain measure of their quantity, and the question to he determined relates to the adequacy and the source of the supply. That question I shall not now attempt to answer; but, obviously, if the volcanic hypothesis be true, the cessation of volcanism would signify the end of life on the globe. It would be followed by the consumption of all available carbon dioxide, so that plant life, and consequently animal life, could no longer be supported. A cosmical atmosphere has no assignable limit ; an atmosphere of volcanic origin must sooner or later be exhausted. May not the moon be an example of such an atmos- pheric death? 5 Another theory relative to the atmosphere is based upon the belief that the unoxidized, but oxidizable, substances in the primitive rocks are sufficient in quantity to absorb all the oxygen of the air. If our globe solidified from a molten condition, and if, as commonly sup- 1 For a curious speculation on the mass of the atmosphere, see R. H. McKee, Science, vol. 23, 1906, p. 271. He argues that the present atmosphere is as great as the earth is capable of retaining. 2 Am. Jour. Sci., 3d ser., vol. 19, 1880, p. 349. 2 Science, vol. 2, 1883, p. 820. 4 Compt. Rend., vol. 87, 1878, p. 541. 6 It is probable that the combustion of carbonaceous meteorites in the atmosphere may add carbon dioxide to it, but the quantity so supplied can hardly be estimated. It is possibly large. THE ATMOSPHERE. 55 posed, oxidized compounds were the first to form, the observed con- ditions are not easy to explain. C. J. Koene, indeed, assumed that the primitive atmosphere contained no free oxygen, and he has been followed of late years by T. L. Phipson, 1 J. Lemberg, 2 John Steven- son, 3 and Lord Kelvin. 4 Lemberg and Kelvin, however, do not go to extremes, but admit that possibly some free oxygen was present even in the earliest times. Lemberg argued that the primeval atmos- phere contained chiefly hydrogen, nitrogen, volatile chlorides, and carbon compounds, the oxygen which is now free being then united with carbon and iron. The liberation of oxygen began with the appearance of low forms of plant life, possibly reached a maximum in Carboniferous time, and has since diminished. Stevenson’s argu- ment is much more elaborate, and starts with an estimate of the uncombined carbon now existent in the sedimentary formations. In the deposition of that carbon, oxygen was liberated, and from data of this kind it is argued that the atmospheric supply of oxygen is steadily increasing, while that of carbon dioxide diminishes. The statement that no oxygen has been found in the gases extracted from rocks is also adduced in favor of the theory. First, an oxidized crust and no free oxygen in the air; then processes of reduction coming into play; and at last the appearance of lower forms of plants, which pre- pared the atmosphere to sustain animal life. The arguments are inge- nious, but to my mind they exemplify the result of attaching excessive importance to one set of phenomena alone. It is not clear that due account has been taken of the checks and balances which are actually observed. At present the known losses of oxygen seem to exceed the gains. For example, C. H. Smyth 5 6 has estimated that the oxygen withdrawn from the air by the change of ferrous to ferric compounds, and so locked up in the sedimentary rocks, is equal to 68.8 per cent of the quantity now present in the atmosphere. But were oxidized compounds the first compounds to form? If they were, then the arguments just cited are valid, but the premises are doubtful. If the molten globe was as hot as has been supposed, it is likely that carbides, silicides, nitrides, etc., would be generated first, and in that case all the oxygen of the lithosphere would be atmospheric. This supposition is based upon the results obtained with the aid of the electric furnace at temperatures which decompose oxygen compounds in the presence of carbon, silicon, or nitrogen, substances of the class just named being then produced. Considera- 1 Chem. News, vol. 67, 1893, p. 135. Also several notes in vols. 68, 69, and 70. For Koene’s work see Phip- son’s papers, 1893-94. 2 Zeitschr. Deutsch. geol. Gesell., vol. 40, 1888,- pp. 630-634. 3 Philos. Mag., 5th ser., vol. 50, 1900, pp. 312, 399; 6th ser., vol. 4, 1902, p. 435; vol. 9, 1905, p. 88; vol. 11, 1906, p.226. * Idem, 5th ser., vol. 47, 1899, pp. 85-89. 6 Jour. Geology, vol. 13, 1905, p. 319. 56 THE DATA OF GEOCHEMISTRY. tions of this kind have been elaborately developed by H. Lenicque , 1 who, however, pushes them to extremes. He even goes so far as to ascribe great masses of limestone to the atmospheric oxidation of primitive carbides. It will be observed at once that theories of this order are directly related to the hypotheses which postulate an inor- ganic origin for petroleum — a subject which will be more fully dis- cussed in the proper chapter. For the present it is enough to see that cogent arguments may lead us to either of two opposite beliefs — that the primitive atmosphere was rich in oxygen, or that it was oxygen free. The balance or lack of balance between carbon and oxygen is, after all, only one factor in the problem. The origin of the atmosphere as a whole is a much larger question, and our answers to it must depend upon our views as to the genesis of the solar system. If we accept the nebular hypothesis, we are likely to conclude that the atmosphere is merely a residuum of uncombined gases which were left behind when the globe assumed its solid form. That seems to be the prevalent opinion, although it must be modified by the observed facts of volcanism. The outer envelope of the earth receives rein- forcements from within, whose sources will be considered at length in another chapter. Quite a different theory of the earth’s origin has lately been de- veloped by T. C. Chamberlin , 2 who imagines a planet built up by slow aggregations of small, solid bodies. Each of these particles, or meteorites, carried with it entangled or occluded atmospheric mate- rial. In time the accumulation of originally cold matter developed pressure enough to raise the central portions of the mass to a high temperature, and gases were then expelled. Thus the atmosphere was generated from within the globe instead of remaining as a residuum around it. We know that meteorites contain occluded gases, and that gases are also extractable from igneous rocks, and these facts lend to the hypothesis a certain plausibility. The gases thus obtainable from the lithosphere are equivalent to many potential atmospheres, although, as we have already seen, oxygen is not among them. On Chamberlin’s hypothesis the atmosphere has grown from small beginnings; the nebular conception assumes that it was largest at first. E. H. L. Schwarz , 3 who accepts Chamberlin’s views, con- cludes that the primitive atmosphere is actually represented to-day by the gases extractable from meteorites. Hydrogen, nitrogen, me- thane, and both oxides of carbon are the gases in question, but there is no free oxygen. 1 M4m. Soc. ingen. civils France, October, 1903, p. 346. * Join. Geology, vol. 5, 1897, p. 653; vol. 6, 1898, pp. 459, 609; vol. 7, 1899, pp. 545, 667, 751. See also H. L. Faircbild, Am. Geologist, vol. 33, 1904, p. 94. 3 Causal geology, London, 1910, p. 93. THE ATMOSPHERE. 57 One curious speculation, which may be connected with the theory just described, relates to the nature of the earth’s interior. From the known fact that the temperature rises as we descend into the crust of the earth, calculations have been made to show that the tem- perature of the centrosphere must be enormously high. In fact, if the rate of increase is constant, the temperature must reach a degree far above the critical point of any known element. Matter in the interior of the earth, then, should be gaseous or quasi-gaseous. This suggestion was first offered by Herbert Spencer , 1 later by A. Ritter , 2 and has been more recently developed by S. Arrhenius . 3 It has, however, only speculative value, for it rests upon assumptions which can not be tested experimentally, and which may never be verified. A discussion of the subject falls without the scope of this memoir, and only these brief references to it are admissible here . 4 1 See his essays on the nebular hypothesis (1858) and the constitution of the sun (1865). Cited from New York edition of 1892. 2 Wied. Annalen, vol. 5, 1878, p. 405. 3 Geol. Foren. Forhandl., vol. 22, 1900, p. 395. * For a historical summary relative to the supposed gaseous interior of the earth see S. Gunther, Jahresb. Geog. Gesell. Miinchen, 1890-91, Heft 14, p. 1. See also the monograph by H. Thiene, Temperatur und Zustand des Erdinnern, Jena, 1907. CHAPTER III. LAKES AND RIVERS. 1 ORIGIN. When rain falls upon the surface of the earth, bringing with it the impurities noted in the preceding chapter, part of it sinks deeply underground to reappear in springs. Another part runs off directly into streams, a part is retained as the ground water of soils and the hydration water of clays, and a portion returns by evaporation to the atmosphere. According to an estimate by Sir John Murray, 2 the total annual rainfall upon all the land of the globe amounts to 29,347.4 cubic miles, and of this quantity 6,524 cubic miles drain off through rivers to the sea. A cubic mile of river water weighs 4,205,650,000 tons, approximately, and carries in solution, on the average, about 420,000 tons of foreign matter. In all, about 2,735,000,000 tons of solid substances are thus carried annually to the ocean. 3 Suspended sediments, the mechanical load of streams, are not included in this estimate; only the dissolved matter is considered, and that repre- sents the chemical work which the percolating waters have done. Although the minerals which form the rocky crust of the earth are relatively insoluble, they are not absolutely so. The feldspars are especially susceptible to change through aqueous agencies, yielding up their lime or alkalies to percolating water and forming a residue of clay. Rain water, as we have already seen, contains carbonic acid in solution, and that impurity increases its solvent power, particularly with regard to limestones. The moment that water leaves the atmosphere and enters the porous earth its chemical and solvent activities begin, and continue, probably without interruption, until it reaches the sea. The character and extent of the work thus done varies with local conditions, such as temperature, the nature of the minerals encountered, and so on; but it is never zero. Sometimes larger and sometimes smaller, it varies from time to time and place to place. The entire process of weathering will be considered more fully later; we have now to study the nature of the dissolved matter alone, or, in other words, the composition of rivers and lakes. The 1 Excluding those belonging to closed basins. 2 Scottish Geog. Mag., vol. 3, p. 65, 1887. 3 Estimates by F. W. Clarke (A preliminary study of chemical denudation: Smithsonian Misc. Coll., vol. 56, No. 5, 1910). Murray’s figures are 762,587 tons per cubic mile, and nearly 5,000,000,000 tons in the total run-oS. His analytical data were too few and too limited in range for a close computation. LAKES AND RIVERS. 59 data are abundant, but unfortunately complicated by a lack of uni- formity in the methods of statement, which latter are often unsatis- factory and even misleading. The analysis of a water can be reported in several different ways, as in grains per gallon or parts per million; in oxides, in supposititious salts, or in radicles; so that two analyses of the same material may seem to be totally dissimilar, although in reality they agree. Before we can compare analyses one with another we must reduce them to a common standard, for then only do their true differences appear. The task of reduction may be tedious, but it is profitable in the end. STATEMENT OF ANALYSES. In the usual statement of water analyses an essentially vicious mode of procedure has become so firmly established that it is difficult to set aside. For example, a water is found to contain sodium, potassium, calcium, magnesium, chlorine, and the radicles of sul- phuric and carbonic acids; or, in ordinary parlance, three acids and four bases. If these are combined into salts at least 12 such compounds must be assumed, and there is no definite law by which their relative proportions can be calculated. A combination, how- ever, is commonly taken for granted, and each chemist allots the several acids to the several bases according to his individual judg- ment. The 12 possible salts rarely appear in the final statement; all the chlorine may be assigned to the sodium and all the sulphuric acid to the lime, and the result is a meaningless chaos of assumptions and uncertainties. We can not be sure that the chosen combinations are correct, and we know that in most analyses they are too few. But are the radicles combined ? This is a point at issue. Although no complete theory, covering all the phonemena of solution, has yet been developed, it is the prevalent opinion, at least among physical chemists, that in dilute solutions the salts are dissociated into their ions, and that with the latter only can we legitimately deal. Whether this theory of dissociation shall ultimately stand or fall is a question which need not concern us now; we can use it without danger of error as a basis for the statement of analyses, putting our results in terms of ions which may or may not be actually combined. 1 Upon this foundation all water analyses can be rationally compared, with no unjustifiable assumptions and with all the real data reduced to the simplest uniform terms. We do not, however, get rid of all difficulties, and some of these must be met by pure conventions. For example, Is silica present in colloidal form, or as the silicic ion Si0 3 ? 1 The ionic form of statement has been used in the Survey laboratory since 1883. In Europe it has had strong advocacy from Prof. C. von Than, Min. pet. Mitt., vol. 11, 1890, p. 487. It is now rapidly supplant- ing the older system. For an excellent discussion of the statement of water analyses, see It. B. Dole, Jour. Ind. Eng. Chem., vol. 6, 1914, p. 770. 60 THE DATA OF GEOCHEMISTRY. Are ferric oxide and alumina present as such, or in the ions of their salts ? The iron may represent ferrous carbonate, the alumina may be equivalent to alum; but as a rule the quantities found are so trivial that the true conditions can not be determined from the ratios between acidic and basic radicles. The unavoidable errors of analysis are commonly too large to permit a final settlement of these questions; and only in exceptional cases can definite conclusions be drawn. For convenience, then, we may regard these substances as col- loidal oxides and tabulate them in that form. 1 The procedure may not be rigorously exact, but the error in it is usual Ly very small. If we consider an analysis as representing the composition of the anhydrous inorganic matter which is left when a water has been evaporated to dryness, the difficulty as regards iron disappears, for ferrous carbonate is then decomposed and ferric oxide remains. A similar difficulty in respect to the presence of bicarbonates also vanishes at the same time, for the bicarbonates of calcium and mag- nesium can only exist in solution and not in the anhydrous residues. If in a given water notable quantities of lime, magnesia, and car- bonic acid are found, bicarbonic ions must be present, for without them the bases could not continue dissolved; but after evapora- tion only the normal salts remain. Sodium and potassium bicar- bonates are not so readily broken down; but even with them it is better to compare the monocarbonates, so as to secure a uniformity of statement. In fact, some analysts report only normal salts, and others bicarbonates; so that for the comparison of different analyses we are compelled to adopt an adjustment such as that which is here proposed. In other words, we eliminate the variable factors and study the constants alone. One other large variable remains to be considered — the variation due to dilution. A given solution may be very dilute at one time and much more concentrated at another, and yet the mineral content of the water is possibly the same in both cases. For example, average ocean water contains 3.5 per cent of saline matter, while that of the Black Sea carries little more than half as much; and yet the salts which the two waters yield upon evaporation are nearly, if not quite, identical. In some cases, as we shall presently see, it is desirable to compare waters directly; but in most instances it is also convenient to study the composition of the solid residues in percentage terms. In that way essential similarities are brought to light and the data become intelligible. Before proceeding farther, it may be well to consider a single water analysis, in order to illustrate the various methods of state- 1 This rule applies to such waters only as are considered in this chapter. To many volcanic waters, geyser waters, mine waters, etc., it does not apply. Their discussion is left to later chapters. LAKES AND RIVERS. 61 ment. For this purpose I will take W. P. Headden’s analysis of water from Platte River near Greeley, Colo., 1 which he himself states in several forms. In the first column of the subjoined table the results are given in oxides, etc., as in a mineral analysis, and in grains to the imperial gallon. In the second column they are stated in terms of salts, and I have here recalculated Headden’s figures into parts per million of the water taken. Finally, in a third column I give, as proposed in the foregoing pages, the composition of the residue in radicles or ions and in percentages of total anhydrous inorganic solids. Analysis of water stated in different forms. Si0 2 Grains per imperial gallon. . . . . 0. 891 CaS0 4 Parts per million. 457. 7 Si0 2 Per cent. . . . . 1. 26 so 3 .... 32.601 MgS0 4 236. 0 S0 4 .... 55.28 co 2 . . . . 4. 554 k 2 so 4 9.4 co 3 . . . . 8. 78 Cl . . . . 2. 681 Na 2 S0 4 62.5 Cl . . . . 3. 79 Na 2 0 .... 11.463 NaCl 63.2 Na .... 12.02 K 2 0 355 Na 2 C0 3 156. 9 K 41 CaO .... 13.117 Na-jSiOg 21.9 Ca .... 13.24 MgO . . . . 5. 530 (FeAl) 2 0 3 2.7 Mg . . . . 4. 69 (FeAl) 2 0 3 189 Mn 2 0 3 2.7 f 2 o 3 53 Mn 2 0 3 189 Ignition 34.2 100. 00 Ignition . . . . 2. 397 Excess S10 2 1.3 “Ignition” o mitte d . Less 0=C1 73. 967 604 73. 363 1, 048. 5 Salinity, 1,014 million. parts per So far as appearance goes, these statements might represent three different waters; and yet the analytical data are the same. A change in the last column of Si0 2 into the radicle SiO s would affect the other figures but slightly. The compactness and simplicity of the ionic form of statement are evident at a glance. Under it, as “salinity,” I have given the concentration of the water in terms of parts per million. One million parts of this water contain in solution 1,014 parts of anhydrous, inorganic, solid matter. THE INTERPRETATION OF ANALYSES. In the interpretation of any water analysis the first question to ask is as to its accuracy. Every analysis is subject to errors, great or small, and in each individual instance it is important to decide whether its error is serious or negligible. When an analysis is stated in terms of salts, the errors are obscured, as in the smoothing of a curve, and an accurate estimate of its value is not possible. In 1 Bull. Colorado Agr. Exper. Sta. No. 82, 1903, p. 56. 62 THE DATA OF GEOCHEMISTRY. such a case the reputation of the analyst is the safest criterion upon which to base a judgment. When, however, an analysis is stated in terms of the radicles actually determined, a decision as to its value is much simpler. The negative or acid radicles and the positive or basic radicles must be chemically equivalent, at least within the limits of permissible experimental errors. To this rule, which applies to nearly all waters, there are some apparent but not real exceptions. If the basic radicles are much in excess of the acid, it is possible that a part of the alkaline ions may be balanced or held in equilibrium by silica; that is, the usually colloidal silica may represent an alkaline silicate; which, however, is hydrolyzed in solution. Some geyser waters of the Yellowstone National Park have this peculiarity. On the other hand, certain volcanic waters are strongly acid; and then it is nec- essary to assume the presence of hydrogen ions in order to completely balance the negative radicles. Another source of acidity is found in some mineral springs, in which the iron and aluminum are pre- sumably in equilibrium as sulphates. The iron and aluminum must then be counted, not as colloids, but as among the basic radi- cles. Examples of these exceptional waters are cited in chapter 6 of this treatise, and demand no further attention here. The calculations implied in the preceding paragraph are very simple, and may be based either upon the analysis as stated in parts per million or upon its percentages. The quantity found for each radicle is divided by its chemical equivalent, and the quotients for each group, acid or basic, are separately added together. The two sums should then be equal, or so nearly equal that the difference can be ascribed to the small, inevitable errors of analysis. For the univalent radicles Na, K, Cl, N0 3 , and HC0 3 the chemical equiva- lent and the atomic weight are the same; for the bivalent radicles Ca, Mg, S0 4 , and C0 3 the atomic weights should be halved. This is the usual procedure. H. Stabler, 1 however, has proposed a modi- fication of the method, in which the quantities determined are multiplied by the reciprocals of the equivalents, which he calls the “ reaction coefficients” of the radicles. The products so obtained, the “ reacting values” of the radicles, are identical with the quotients of the ordinary process and must balance in the same way. A table of Stabler’s coefficients may save some labor when large numbers of analyses are to be discussed, but the economy is probably small. The interpretation of a water analysis, then, is founded upon a study of equilibria. Even the hypothetical combination of the radicles is a crude attempt at such a study — an attempt, however, which, as we have already seen, is based ordinarily upon un verifiable assumptions. I speak now, of course, of such waters as commonly occur in nature. A solution of a single salt, or one in which, as in 1 Water-Supply Paper U. S. Geol. Survey No. 274, 1911, pp. 165-181. LAKES AND EIVEES. 63 certain brines, one salt overwhelmingly predominates, is obviously easy to deal with. A more refined attack upon the problem of inter- pretation has been made by Chase Palmer, 1 who has examined in detail the relations between the equivalent ratios or reacting values described above, and so correlated the analyses with the properties of the waters analyzed. His procedure, briefly, is as follows: Two fundamental properties are recognized — namely, alkalinity and salinity, which are subdivided into groups. Salinity is measured by the sum of the strong-acid radicles, S0 4 , Cl, and N0 3 , which balance an equivalent number of basic radicles. If the basic radicles are partly or wholly alkaline, that is, Na or K, their proportion of the salinity is said to be 'primary . The remaining salinity, due to the radicles Ca, Mg, and Fe" is called secondary. If, however, the acid radicles are in excess of the basic, tertiary salinity or acidity appears, and hydrogen ions must be taken into account. When the alkaline radicles exceed those of the strong acids, their excess is the measure of primary alkalinity, which represents hydrolyzed carbonates or bicarbonates. The weak-acid radicles C0 3 and HC0 3 , which balance any excess of the alkaline earths over the stronger acids, produce secondary alkalinity. Upon these properties Palmer has developed a classification of natural waters, which correlates them with their geologic origin. Waters issuing from areas of crystalline, feldspathic rocks, are char- acterized by high primary alkalinity, low concentration, and a notable proportion of silica. Waters from sedimentary regions, especially where limestone is abundant, show secondary alkalinity. Ocean water and other similar brines are almost entirely saline, and alkalinity is nearly or even wholly wanting in them. Palmer gives numerous, carefully worked out, illustrations of the applicability of his method of discussion to geochemical problems, but the details can not well be presented here. SPRINGS. When water first emerges from the earth as a spring its mineral composition is dependent upon local conditions. Some spring waters are exceedingly dilute; others are heavily charged with saline impuri- ties. To the subject of “ mineral” springs, a separate chapter will be given, and only a few analyses of spring water, all taken from the records of the United States Geological Survey, need be given here. They represent the beginnings of streams, and are there- fore significant in this connection. All these analyses are reduced to a uniform standard, in accordance with the rules laid down in the preceding pages. 2 1 The geochemical interpretation of water analyses: Bull. U. S. Geol. Survey No. 479, 1911. 2 innumerable analyses of wells, springs, and underground waters generally are to he found scattered through the literature. See for example, S. W. McCallie, Bull. Geol. Survey Georgia No. 15, 1908, and E. Bartow, Bull. Univ. Illinois, vol. 6, No. 3, 1908. 64 THE DATA OF GEOCHEMISTRY. Analyses of spring water. A. Sprirg near Magnet Cove, Arkansas. Analysis by H. N. Stokes. B. Spring 1 mile west of Santa Fe, New Mexico. Analysis by F. W. Clarke. C. Spring near Mountain City, Tennessee. Analysis by T. M. Cbatard. D. Caledonia Spring, Caledonia, New York. Analysis by H. N. Stokes. E. Spring 3 miles west of Lowesville, North Carolina. Analysis by F. W. Clarke. F. Spring near Mount Mica, Paris, Maine. Analysis by F. W. Clarke. A B c D E F co 3 53. 59 47. 14 27. 29 11. 73 12. 15 6. 22 so 4 3. 40 6. 67 16. 37 31. 62 51. 86 60. 97 Cl 1. 35 4. 18 1. 50 22. 28 . 45 Trace. Ca 30. 95 22. 67 14. 39 19. 49 23. 58 22. 37 Mg 3. 45 6.17 2. 23 3. 25 1.47 2. 62 Na 1. 08 | 5.32 5. 72 10. 62 4. 16 4. 32 K . 63 3. 97 .34 .34 .21 Si0 2 5. 55 7. 85 27. 17 .67 5. 99 2. 80 A1 2 0 3 Trace. Fe 2 0 3 1. 36 .49 Salinity, parts per million | 100. 00 224 100. 00 280 100. 00 80 100. 00 925 100. 00 642 100. 00 606 Some of these waters yield carbonates on evaporation, one yields mainly sulphates, and between the two extremes the carbonic and sulphuric radicles vary almost reciprocally. One water is character- ized by its high proportion of chlorine and another by its large per- centage of silica; but in all of them calcium is the dominant metal. In salinity they differ somewhat widely, but the most concentrated example contains only 925 parts per million, or 52 grains to the United States gallon, of foreign solids. It will be seen as we go farther that carbonate waters are the most common, for the reason that rain water brings carbonic acid from the air, and that substance is most active as a solvent of mineral matter. CHANGES OF COMPOSITION. As spring water flows from its source it rapidly changes in char- acter. It receives other water in the form of rain or of ground water flowing from the soil, and it blends with other rivulets to produce larger streams. Under certain conditions a part of its dissolved load may be precipitated, and the composition of a river as it approaches the sea represents the aggregate effect of all these agencies. A river is the average of all its tributaries, plus rain and ground water, and many rivers show also the effects of contamination from towns and factories. Small streams are the most affected by local conditions, and show the greatest differences in composition; large rivers, as a rule, resemble one another more nearly. How rapidly and how profoundly the composition of a river may be modified are well illustrated in Headden’s bulletin, which I have LAKES AND RIVERS. 65 already cited. 1 Cache la Poudre River in Colorado flows first through a rocky canyon, over bowlders of schist and granite, and thence emerges upon the Plains. Its waters are then diverted into ditches and reservoirs for purposes of irrigation, and finally reach the Platte near Greeley. In performing the work of irrigation they acquire a new load of solid matter, and the progressive changes in their com- position are clearly shown by Headden’s analyses. Some of the latter I will cite, first, as Headden gives them in grains to the imperial gallon, and then in a second table reduced to ions and percentages. Analysis E is the one cited on page 59 to show different forms of statement. In all cases I omit Headden’s figures for “ignition,” and deal with the anhydrous residues alone. Analyses of water from Colorado rivers. A. Cache la Poudre River above the north fork. B. Cache la Poudre River water from faucet in laboratory at Fort Collins. C. Cache la Poudre River 2 miles above Greeley. D. Cache la Poudre River 3 miles below Greeley. E. Platte River below mouth of the Cache la Poudre. Grains per imperial gallon. A B c D E co 2 0. 6029 2. 3731 5. 920 5. 087 4. 554 so 3 . 1916 1. 8699 54. 970 30. 374 32. 601 Cl . 1037 . 1055 2. 770 2. 145 2. 681 CaO .5238 3. 0364 18. 938 14. 087 13. 117 SrO Trace. . 0223 MgO . 1257 . 8857 12. 190 5. 592 5. 539 Na 2 0 . 3750 . 6631 14. 590 9. 117 11. 463 K 2 0 .0855 . 1921 . 451 . 372 . 355 Si0 2 . 6053 . 6245 1.035 . 951 . 891 (Al,Fe) 2 0, .0113 .0171 . 079 . 039 . 189 MrioOo .0018 .0112 Trace. .078 .189 Less 0=C1 2. 6296 .0234 9. 8009 .0238 110. 943 .624 67. 842 .483 71. 570 .604 2. 6062 9. 7771 110. 319 67. 359 70. 966 Reduced analyses, in percentages. co 3 31. 91 33. 68 7. 34 10. 34 8. 78 so 4 9. 07 23. 36 59. 99 54. 33 55. 28 Cl 4. 03 1. 10 2. 52 3. 19 3. 79 Ca 14. 53 22. 58 12. 31 15. 00 13. 24 Sr . 19 Mg 2. 93 5. 53 6. 65 5. 00 4. 69 Na 10. 80 5. 12 9. 84 10. 09 12. 02 K 2. 72 1. 66 .34 .46 .41 Si0 2 23. 50 6. 49 .94 1. 42 1. 26 .51 .29 .07 .17 .53 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 37 137 1, 571 958 1,011 i Bull. Colorado Agr. Exper. Sta. No. 82, 1903. 97270°— Bull. 610—16 5 66 THE DATA OF GEOCHEMISTRY. We have here, first, a very pure mountain water, relatively high in carbonates and rich in silica. At the end of the series we have waters in which sulphates predominate and the proportion of silica is very low. The change is extremely great in all respects, and is partly due to the use of the water for irrigating an originally arid soil containing much soluble matter. Probably when the soil shall have been thoroughly leached by long periods of cultivation the changes in the water will be less exaggerated. A similar alteration is also shown in Headden’s analyses of water from Arkansas River, first at Canon City, where it emerges from the mountains, and second at Rockyford, nearly 100 miles below. 1 The analyses are as follows, reduced to the common standard adopted in this memoir. Headden regards the silica as present partly in the form of alkaline silicates, a supposition which is probably correct. F or present purposes, however, the difference between Si0 2 and the Si0 3 radicle may be neglected. Analyses of water from Arkansas River at two points in Colorado. Canon City. Rockyford. co 3 37. 55 2. 65 so 4 14. 62 60. 69 Cl 3. 77 4.89 12. 78 Ca 20. 24 Mg 5. 13 3. 76 Na 9. 57 14. 50 K . 60 .28 sio 2 : 8. 19 .45 Ro(X . .33 Salinity, parts per million 100. 00 148 100. 00 2, 134 Changes of a different order are shown by the waters of the River Chelif, in Algeria, according to the investigation by L. Ville. 2 This stream flows through an arid region, in which incrustations or efflores- censes of salt and gypsum abound. Lower in its course it receives affluents much poorer in mineral matter, and its character, at least as regards salinity, is modified. Ville’s analyses reduced to a modern standard are as follows: 1 Bull. Colorado Agr. Exper. Sta. No. 82, 1903. Headden also gives analyses of water from St. Vrain, Big Thompson, Boulder, and Clear creeks, and from many reservoirs, irrigating ditches, and wells. See also Am. Jour. Sci., 4th ser., vol. 16, 1903, p. 169. 2 Bull. Soc. g6ol. France, 2d ser., vol. 14, 1857, p. 352. A later analysis by Balland is given in Jour. Chem. Soc., vol. 36, 1879, p. 699, abstract. Still another, by F. de Marigny, is cited by Roth. In Annales des mines, 5th ser., vol. 11, 1857, p. 667, Marigny gives analyses of two other Algerian rivers. LAKES AND RIVERS. 67 Analyses of water from River Chelif, Algeria. A. Sample taken at Ksar-Boghari during extreme low water. B. Sample taken at the same point a few days later, after a rise. C. Sample from Orleansville, much farther downstream. A B C co 3 0. 93 1. 11 9. 31 so 4 40. 36 25. 87 29. 64 Cl 26. 40 39. 28 26. 54 Ca 7. 46 6. 63 11. 85 Ms. 4. 12 4. 42 4. 11 Na 20. 64 22. 61 17. 03 Si0 2 .06 . 04 . 34 FeXL . .03 .04 1. 18 Salinity, parts per million 100. 00 6,670 100. 00 5, 342 100. 00 1, 182 The effect of dilution by affluents is shown by analysis C; but the interesting feature of the series is the difference between high and low water at Ksar-Boghari. Ville attributes this difference to the fact that salt is much more soluble than gypsum and that therefore during a flood it is dissolved out more freely and more rapidly from the soil. At low water sulphates are in excess of chlorides ; at high water the reverse is true. The examples thus far cited serve to show the danger of attempting to draw general conclusions from a single analysis of a water, espe- cially when the latter is collected at only one point. If we wish to determine the total load carried by a river to the ocean, the samples should be taken as near as possible to its mouth, but far enough up- stream to avoid tidal contamination; and the analyses should be numerous enough to give a fair average result. Without such pre- cautions no valid conclusions can be reached. The data must be adequate to the purpose in view — a condition which is not always fulfilled. 68 THE DATA OF GEOCHEMISTRY. ANALYSES OF RIVER WATERS. Many analyses of river and lake water are to be found scattered through chemical and geological literature. Only a part of the material can be considered here, and preference will be given but not exclusively, to analyses not cited in the classical works of J. Roth and G. Bischof. Many of the analyses were made in the laboratories of the United States Geological Survey and especially in those of the water-resources branch. The work of that branch, in this particular direction, is mainly but not exclusively represented by six publi- cations, 1 in which a large number of American rivers have been studied with remarkable exhaustiveness. For each river or lake many analyses were made, in such a manner as to give its average composition for an entire year. As a rule, samples of water were taken daily, and combined into composite samples of seven to ten which were analyzed. The analyses, however, some thouands in number, are not absolutely complete. Alumina, for example, was not determined, and the alkalies, as a rule, were weighed together and calculated as all sodium. Later work, by Chase Palmer, cor- rected the latter omission, and I have been able to recalculate the published analyses with the introduction of Palmer’s figures 2 for Na and K. All the analyses cited in the following pages have been reduced to the uniform standard which was outlined in the preceding pages; but the original figures can usually be found through the references to the literature. In addition to the substances enumerated in the analyses, waters contain many other constituents in minute, almost undeterminable traces. One of those, fluorine, has recently been determined in several river waters by A. Gautier and P. Claus- mann. 3 The quantities found ranged from 0.02 to 0.6 milligram per liter, being highest in waters emerging from primitive rocks. 1 Water-Supply Papers No. 236, by R. B. Dole, 1909; No. 237, by Walton Van Winkle and F. M. Eaton, 1910; No. 239, by W. D. Collins, 1910; No. 273, by H. N. Parker and E. H. S. Bailey, 1911; and Nos. 339 and 363, by W. Van Winkle, 1914. Water-Supply Paper No. 274, by Herman Stabler, also contains many analyses of river waters. 2 Supplied by Palmer. For details see Bull. U. S. Geol. Survey No. 479, 1911. a Compt. Rend., vol. 158, 1914, p. 1389. LAKES AND RIVERS. 69 THE ST. LAWRENCE BASIN. For geological purposes a regional classification of the data would seem to be the most practicable, for the members of a river system belong naturally together. Taking North American rivers first in order, let us begin with the St. Lawrence and its tributaries. The selected analyses are as follows: Analyses of water from the Great Lakes and the St. Lawrence. A. Lake Superior at Sault Ste. Marie. Mean of 11 analyses of samples taken monthly between Sep- tember 22, 1906, and August 22, 1907. Other analyses of Lake Superior water have been made by W. A. Noyes, Eleventh Ann. Rept. Minnesota Geol. Survey, 1882, p. 174; by W. F. Jackman, cited by A. C. Lane in Water-Supply Paper U. S. Geol. Survey No. 31, 1899, p. 27; and by G. L. Heath, Rept. State Board Geol. Survey Michigan, 1903, p. 119. B. Lake Michigan at St. I gnace. Mean of 11 samples taken between September 20, 1906, and August 20, 1907. Analyses of Lake Michigan water at Milwaukee and of Milwaukee River, by G. Bode, are pub- lished in Geology of Wisconsin, vol. 1, 1883, p. 308. Another analysis of the lake water, by J. H. Long, is given in Report on the boiler waters of the Chicago, Burlington & Quincy Railroad, published by that company in 1888. C. Lake Huron at Port Huron. Mean of 9 samples taken between September 21, 1906, and June 21,1907. D. Lake Erie at Buffalo. Mean of 11 samples taken between September 19, 1906, and August 28,1907. E. The St. Lawrence at Ogdensburg. Mean of 11 samples taken between September 18, 1906, and August 19, 1907. Analyses A to E by R. B. Dole and M. G. Roberts. See Water-Supply Paper U. S. Geol. Survey No. 236. F. The St. Lawrence at Pointe des Cascades, near Vaudreuil, above Montreal. Analysis by T. Sterry Hunt, Philos. Mag., 4th ser., vol. 13, 1857, p. 239. G. The St. Lawrence opposite Montreal. Analysis by Norman Tate, cited by T. Mellard Reade, in Evolution of earth structure, 1903. A B c D E F G co 3 47.42 49. 45 47. 26 44. 70 45. 70 41. 66 44. 43 so 4 3. 62 6. 15 5. 77 9. 83 9. 15 5. 19 11. 17 Cl 1. 89 2. 31 2. 42 6. 58 5. 87 1. 51 2. 41 NO, . 86 . 26 . 38 .23 . 23 Ca 22. 42 22. 21 22. 33 23. 45 23. 66 20. 08 20. 67 Mg 5. 35 7. 01 6. 52 5. 75 5.49 4. 52 6. 44 Na \ 5.52 \ 4.02 \ 4.10 \ 4.92 \ 4.81 3. 20 4. 87 K / / / / / . 72 Si0 2 12. 76 8. 54 11. 16 4. 46 5. 03 23. 12 10. 01 Fe 9 0o . 16 .05 .06 .08 .06 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per mil- lion 0. 60 118 108 133 134 160 148 70 THE DATA OF GEOCHEMISTRY. The following analyses represent tributaries to the St. Lawrence : 1 Analyses of water from tributaries to the St. Lawrence. H. Pigeon River, Minnesota. Analysis by W. A. Noyes, Eleventh Ann . Rept. Minnesota Geol. Survey, 1882, p. 174. I. Grand River at Grand Rapids, Michigan. Mean of 34 composites of samples taken between October 1, 1906, and October 5, 1907. Analyses by R. B. Dole, M. G. Roberts, C. Palmer, and W. D. Collins. J. Kalamazoo River near Kalamazoo, Michigan. Mean of 35 composites, September 19, 1906, to Sep- tember 21, 1907. Same analysts as under I. K. Maumee River at Toledo, Ohio. Mean of 36 composites taken between September 9, 1906, and October 7, 1907. Dole, Roberts, and Palmer, analysts. L. Genesee River at Rochester, New York. Analysis by C. F. Chandler, cited by I. C. Russell in Mon. U. S. Geol. Survey, vol. 11, 1885, opp. p. 176. M. Oswegatchie River at Ogdensburg, New York. Mean of 35 composites, September 9, 1906, to Sep- tember 9, 1907. Same analysts as under I. N. Ottawa River at Ottawa, Canada. High water, July, 1907. Analysis by F. T. Shutt and A. G. Spencer, Trans. Roy. Soc. Canada, 3d ser., vol. 2, 1908, p. 175. Another incomplete analysis is also given. O. Lake Champlain. Average of five analyses of samples taken in the broad lake, by M. O. Leighton, Water-Supply Paper U. S. Geol. Survey No. 121, 1905. This paper contains analyses of water from the upper end of the lake, of Bouquet River, and of Ticonderoga Creek. Analyses I, J, K, and M, from Water-Supply Paper 236, contain corrections for the alkalies as furnished by Palmer. An earlier analysis of water from the Maumee, by Chandler, and one of the Ottawa, by T. S. Hunt, are given in the first edition of this book (Bulletin 330). H I J K L M N 0 co 3 42. 00 44. 37 47. 32 29. 63 37. 94 39. 10 35. 44 45. 81 so 4 4. 69 12.88 9. 54 16. 25 25. 29 12.24 8. 57 11.03 Cl 6. 09 3. 00 1.41 13. 55 1. 41 .59 1.42 1. 78 NO, . 89 . 79 1. 52 . 59 Ca 18. 08 21. 85 22. 82 19. 29 24. 48 19. 40 16. 58 21. 19 Mg 5. 74 7. 42 7.47 5. 44 5. 29 5. 23 4. 74 4.21 Na 5. 13 3. 20 2. 87 6. 79 2. 59 6. 57 4. 51 \ 8.80 K 2. 55 .89 .70 1. 62 1.35 1. 80 1. 59 / Si0 2 14. 15 5. 46 7. 05 5. 78 .82 14. 03 20. 03 5. 58 Fe 2 0 3 AloO, 1. 57 .04 .03 . 13 1 .83 J .45 W. 12 J 1 1.60 J o* 1 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 Salinity, parts per million 51 258 242 298 170 77 45 67 a Includes small amounts of P0 4 and Mn 3 0 4 . Between these waters there are distinct resemblances, in that car- bonates are the predominating salts and calcium is the chief metal. Ottawa River is characterized by high silica ; but the Genesee and the Maumee, which flow through areas of sedimentary rocks, contain a larger proportion of sulphates. The increase in salinity or concen- tration in passing from Pigeon River, at the head of Lake Superior, to the St. Lawrence at Montreal is also noteworthy. The two Mont- real analyses, F and G, are, however, far from concordant and can not be given much weight. 1 Other tributaries that have been analyzed are as follows: Goose Lake, Michigan (Geol. Survey Michigan, vol. 8, pt. 3, 1903, p. 235); Torch Lake, Portage Lake, Pine River, Thunder River (Rept. State Board Geol. Survey Michigan, 1903); Traverse Bay, Detroit, Shiawassee, Grand, Cass, Chippewa, Tittabawassee, and Boardman rivers, Manistee and Muskegon lakes, cited by A. C. Lane in Water-Supply Paper U. S. Geol. Survey No. 31, 1903. LAKES AND RIVERS. 71 According to estimates made by engineers of the United States Army, the flow of the St. Lawrence past Ogdensburg is 248,518 cubic feet per second. This, with a salinity of 134 parts per million, cor- responds to a transport of dissolved matter of 29,722,000 metric tons annually. The area drained, exclusive of water surface, is 286,900 square miles, and from each square mile 103.6 tons are removed in solution each year. THE ATLANTIC SLOPE. For the rivers and lakes of the Atlantic slope south of the St. Law- rence the data are now fairly abundant. The subjoined analyses are the most useful. In all of them bicarbonates are reduced to normal form, and organic matter is omitted from the calculation. Analyses of waters of Atlantic slope — I. A. Moosehead Lake, Maine. B. Rangeley Lake, Maine. C. Androscoggin River at Brunswick, Maine, above the falls. Average of 38 analyses of weekly samples taken between April 25, 1905, and January 16, 1906. Analyses A, B, and C made by F. C. Robinson, for the water-resources branch of the United States Geological Survey. C as recalculated by Dole in Water- Supply Paper 236. The undetermined C0 3 is computed to satisfy bases. D. Merrimac River above Concord, New Hampshire. Analysis by H. E. Barnard for the water-resources branch of the Geological Survey. E. Hudson River at Hudson, New York. Mean analysis of 36 weekly composites taken between Sep- tember 16, 1906, and September 22, 1907. Analyses by R. B. Dole, M. G. Roberts, C. Palmer, and W. D. Collins, Water-Supply Paper 236, 1909. Analyses by C. F. Chandler of water from the Hudson and its tributaries, the Mohawk and the Croton, are cited in the first edition of this book (Bulletin 330). F. Raritan River at Bound Brook, New Jersey. Mean of 35 composite samples taken between Sep- tember 10, 1906, and September 12, 1907. Same analysts and reference as under E. Analyses of several New Jersey streams are given by A. H. Chester in the report on water supply, New Jersey Geol. Survey, 1894. An analysis of water from Passaic River, by E. N. Horsford, is published in Geology of New Jersey, 1868, p. 703; and another by H. Wurtz in Am. Chemist, vol. 4, 1873, pp. 99, 133. G. Delaware River at Lambertville, New Jersey. Mean of 34 composite samples, September 8, 1906, to September 12, 1907. Same analysts and reference as under E. A similar average analysis of the Lehigh is also given by Dole. For an earlier, single analysis of Delaware water see H. Wurtz, Am. Jour. Sci., 2d ser., vol. 22, 1856, p. 125. Analyses of water from the Schuylkill are given by C. M. Cresson in a report entitled “Results of examinations of water from the River Schuylkill,” Philadelphia, 1875. H. Susquehanna River, at Danville, Pennsylvania. Mean of 36 composite samples, September 10, 1906, to September 17, 1907. Same analysts and reference as under E. Similar annual averages for the river at West Pittston and W illiamsport are also given by Dole. The Susquehanna shows the effects of contamina- tion by coal-mine drainage. In analyses E, F, G, and H the alkalies are given as corrected by Palmer. A B C D E F G H C0 3 26. 83 26. 53 20. 29 28. 15 35.45 29. 48 32. 95 23.54 so 4 14. 46 13. 08 24. 85 12. 78 15. 84 14. 08 17.49 27. 53 Cl no 3 13. 83 12. 72 4.76 8. 78 3. 96 .79 5. 52 2. 23 4. 23 1. 60 7. 19 3. 02 Ca 14.94 14. 78 15. 33 17. 14 20. 79 14. 08 17.49 18. 64 Mg 1. 80 1. 69 2. 27 4. 18 3. 76 4. 58 4. 81 4. 08 Na 12. 79 11. 63 5. 17 16. 16 6. 53 9. 27 6. 70 6. 84 K 4. 29 4. 42 2. 07 Trace. 1. 78 1. 76 1.46 1. 33 Si0 2 A1 2 0 3 9. 68 | 1.38 13. 33 | 1.82 18. 63 18. 14 1. 34 10. 90 18. 77 13. 12 7. 72 Fe 2 0 3 | 6. 63 3. 33 .20 .23 .15 .11 Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 14.5 16.5 48.3 170 108 85 70 112 72 THE DATA OF GEOCHEMISTRY. Analyses A and B are remarkable because of their relatively high content in alkaline chlorides. These waters, however, are very dilute, and the absolute quantity of chlorides in them is probably no more than they would receive from rainfall. The Androscoggin rises in the Rangeley Lakes, but the composition of its water is pro- foundly modified by drainage from factories and pulp mills. Its head- waters, flowing from a region of crystalline rocks, mainly granitic, are remarkably pure. Analysis of waters of Atlantic slope — II. I. Potomac River at Cumberland, Maryland. Mean composition of 36 composite samples taken between September 11, 1906, and September 14, 1907. Analyses by Dole, Roberts, Palmer, and Collins. J. Shenandoah River at Millville, West Virginia. Composite of 36 samples, September 12, 1906, to September 9, 1907. Same analysts as under I. K. Potomac River above Great Falls, Maryland. Average of twelve samples taken at intervals of one month between April, 1904, and April, 1905. Analyses by Raymond Outwater, Water-Supply Paper U. S. Geol. Survey No. 192, 1907, pp. 296-297. This report contains thirty-four other analyses of water from the upper Potomac and its important tributaries. L. James River at Richmond, Virginia. Composite of 36 samples, September 10, 1906, to September 9, 1907. Same analysts as under I. A thesis by A. F. White, Washington and Lee University, 1906, con- tains partial analyses of tributaries of the James near Lexington, Virginia. See also an analysis of James River water by W. H. Taylor, Rept. to Richmond Board of Health, 1877, cited in the first edition of this book (Bulletin 330). M. Dan River at South Boston, Virginia. Composite of 21 samples, September 3, 1906, to May 2, 1907. Dole, Roberts, and Palmer, analysts. N. Roanoke River at Randolph, Virginia. Composite of 20 samples, September 7, 1906, to May 12, 1907. Same analysts as under M. O. Neuse River at Raleigh, North Carolina. Composite of 36 samples, October 1, 1906, to October 19, 1907. Same analysts as under I. All the analyses in this table except K are recalculated from Water-Supply Paper 236, with the alkali determinations as corrected by Palmer. Each composite sample represents ten daily collections. I J K L M N O co 3 13. 69 47. 22 44. 37 36. 02 25. 43 34. 99 24. 93 so 4 44. 85 4. 43 7. 68 8. 67 5. 34 5. 90 4. 90 Cl 4. 95 2. 14 4.44 2. 81 5. 03 2. 95 6. 34 NO, . 70 1. 86 . 37 1. 73 . 67 .43 Ca 18. 56 22. 85 27. 40 17. 10 8. 79 12. 74 8. 50 Mg 3. 56 5. 86 4. 08 3. 66 2. 35 4. 69 2. 59 Na 6. 11 3. 86 2. 83 7. 20 9. 10 6. 70 10. 09 K 1. 08 1. 00 .55 1. 34 2. 04 1.47 1. 87 Si0 2 A1 ? 0 3 6. 35 10. 71 4. 56 21.98 37. 68 28. 15 37. 47 Fe 2 0 3 .15 .07 | 4. 09 .85 2. 51 1. 74 2. 88 Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 130 140 115 89 71 79 73 The first three analyses in the foregoing table are peculiarly sug- gestive. The Potomac at Cumberland shows the effect of drainage from coal mines. The Shenandoah adds to the Potomac a large volume of water which is little contaminated and which represents to a considerable extent the influence of a limestone country. At Great Falls the Potomac, modified by its numerous affluents, LAKES AND RIVERS, 73 approaches the normal or average type of river waters. According to estimates made by Outwater the Potomac annually carries past Point of Pocks 771,000,000 kilograms of dissolved matter and 212,000,000 kilograms of solids in suspension, or sediments. The sum of the two quantities is 983,000 metric tons, or a little over 102 metric tons per square mile of the territory drained. The dissolved matter corresponds to 80 tons per square mile. Analysis of waters of Atlantic slope — III. P. Cape Fear River at Wilmington, North Carolina. Mean analysis of 30 composite samples taken between October 2, 1906, and October 9, 1907. Dole, Roberts, Palmer, and Collins, analysts. Water probably modified by tidal contamination. * Q. Peedee River near Peedee, North Carolina. Mean of 24 composites, October 26, 1906, to October 19, 1907. Dole, Palmer, Collins, and J. R. Evans, analysts. R. Saluda River near Columbia, South Carolina. Mean of 16 composites, October 27, 1906, to May 3, 1907. Evans, analyst. S. Wateree River near Camden, South Carolina. Mean of 34 composites, October 21, 1906, to October 25, 1907. Dole, Evans, Palmer, and Collins, analysts. T. Savannah River near Augusta, Georgia. Mean of 34 composites, October 25, 1906, to October 22, 1907. Same analysts as under Q. U. Ocmulgee River near Macon, Georgia. Mean of 33 composites, October 19, 1906, to October 21, 1907. Same analysts as under Q. V. Oconee River near Dublin, Georgia. Mean of 32 composites, October 18, 1906, to October 17, 1907. Same analysts as under Q. Analysis P to V are from W ater-Supply Paper 236. Potassium determinations supplied by Palmer. W. Lake Okechobee, Florida. Analysis by W. T. Read, cited by R. B. Dole in Carnegie Inst. Wash- ington Pub. No. 182, 1914, p. 76. Bicarbonates reduced to normal carbonates, organic matter omitted. P Q R s T u V w co 3 26. 57 23. 33 26. 01 25. 15 22. 49 21. 06 26. 00 35. 96 so 4 6. 91 5. 95 8. 01 6.33 9. 12 7. 48 8. 86 4. 69 Cl 12. 52 4. 60 5. 61 4. 22 3.19 4. 28 4. 86 18. 00 no 3 .43 .89 .69 .60 .91 1. 07 1. 43 .06 Ca 10. 80 10. 25 13. 46 9. 49 8. 67 9. 62 12. 14 19. 93 Mg 3. 24 1. 93 2. 08 2. 71 1.22 1. 83 2. 29 4. 50 Na... 14. 04 10. 99 1 9.62 10. 84 14. 42 10. 23 10. 14 10. 28 K 1. 95 2. 82 / 2. 41 4. 12 2. 90 2. 85 1. 28 Si0 2 21. 38 38. 65 33. 65 37. 65 34. 95 39. 70 30. 00 5. 27 Fe 2 C 3 2. 16 .59 .87 .60 .91 1. 83 1. 43 .03 Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 57 69 62 73 60 69 68 155.6 74 THE DATA OF GEOCHEMISTRY- The water of Lake Okechobee is remarkably high in sodium and chlorine. Is this due to cyclic salt brought down in rain ? Analyses of eastern tributaries to the Gulf of Mexico. A. Flint River near Albany, Georgia. Mean analysis of 20 composite samples taken between October 23, 1906, and May 12, 1907. J. R. Evans, analyst. B . Chattahoochee River at W est Point, Georgia. Mean of 34 composites, October 26, 1906, to October 18, 1907. Dole, Evans, Palmer, and Collins, analysts. C. Oostanaula River near Rome, Georgia. Mean of 31 composites, October 21, 1906, to October 28, 1907. Same analysts as under B. D. Cahaba River near Birmingham, Alabama. Mean of 30 composites, November 1, 1906, to November 1, 1907. Same analysts as under B. For a single analysis of water from the Cahaba see R. S. Hodges, Geol. Survey Alabama, U nderground water resources, 1907. This report contains many analyses of springs and wells. E. Alabama’River at Selma, Alabama. Mean of 33 composites, November 5, 1906, to October 17, 1907. Evans, Dole, Palmer, Collins, and W. Van Winkle, analysts. F. Tombigbee River near Epes, Alabama. Mean of 33 composites, October 24, 1906, to October 24, 1907. Same analysts as under B. G. Pearl River, near Jackson, Mississippi. Mean of 32 composites, October 16, 1906, to October 19, 1907. Same analysts as under B. All the analyses in this table are recalculated from Water-Supply Taper 236 and include later alkali determinations by Palmer. A B C D E F G co 3 22. 73 21/32 32. 06 32. 53 27. 86 33. 34 25. 29 so 4 8. 95 8. 49 5. 04 11. 18 10. 63 6. 37 10. 31 Cl 4. 17 3. 96 2. 21 2. 79 2. 72 3. 03 5. 48 no 3 .90 1. 32 .50 .76 .83 .61 1. 12 Ca 13. 12 9. 06 14. 74 16. 52 15. 35 18. 18 11. 43 Mg 2. 09 1. 51 3. 19 3. 17 3. 42 1. 82 1. 77 Na \ 10.44 12. 08 9. 60 8. 78 11. 33 8. 18 11. 59 K / 3. 40 1. 96 3. 18 2.12 2. 32 3. 22 Si0 2 35. 77 37. 73 29. 48 20. 33 24. 79 25. 25 28. 99 Fe 2 0 3 1. 83 1. 13 1. 22 .76 .95 .90 .80 Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 67 52 82 76 82 94 59 A glance at the foregoing table and the two immediately preceding it reveals a remarkable similarity between the waters of the southern rivers from the James to the Pearl inclusive. All are low in salinity and relatively high in silica and the alkalies. In several of the analyses the alkaline radicles are in excess of calcium. River waters, in short, seem to exhibit distinct regional peculiarities, which, in most cases, if not in all, are due to the geology of the region traversed. These waters, with one or two exceptions, flow from areas of crystal- line schists, and owe little to sedimentary environments. LAKES AND RIVERS. 75 THE MISSISSIPPI BASIN. For the great river system of the Mississippi the chemical data are abundant, but of very unequal value. The river itself has been studied from near its source to near its mouth, and the waters of many tributaries have also been analyzed. Taking the Mississippi itself first, the useful data are as follows, arranged in order going southward : Analyses of water from Mississippi River. a A. Mississippi River at Brainerd, Minnesota. Analysis by C. F. Sidener, Thirteenth Ann. Rept. Geol. Nat. Hist. Survey Minnesota, 1884, p. 102. B. Mississippi River at Minneapolis, Minnesota. Average of 35 analyses, by W. M. Barr, H. S. Spauld- ing, and W. Van Winkle, of samples each formed by ten daily collections between September 10, 1906, and September 11, 1907. C. Mississippi River near Moline, Illinois. Mean of 18 composite samples taken between February 1, and July 31, 1906. W. D. Collins, analyst. D. Mississippi River near Quincy, Illinois. Mean of 36 composite samples taken between August 1, 1906, and July 31, 1907. W. D. Collins, analyst. E. Mississippi River near Chester, Illinois. Mean of 31 composite samples taken between August 1, 1906, and July 31, 1907. W. D. Collins, analyst. F. Mississippi River at Memphis, Tennessee. Mean of 35 composite samples taken between January 10, 1907, and January 1, 1908. Analyses by J. R. Evans, W. Van Winkle, R. B. Dole, Chase Palmer, and W. D. Collins. Later alkali determinations by Palmer. G. Mississippi River above Carrolton, Louisiana. Analysis by C. H. Stone, Science, vol. 22, 1905, p. 472. Sample taken 6 feet below surface. Recalculated from bicarbonates. H. Mississippi River at New Orleans. Mean of 52 composite samples taken daily between April 29, 1905, and April 28, 1906. J. S. Porter, analyst. The analyses, except A and G, are recalculated from the figures given by Collins in Water-Supply Paper 239 and Dole in Water-Supply Paper 236. A B C D E F G H CO, 51. 65 48. 03 42. 27 43. 15 33. 23 30. 23 30. 27 34. 98 so 4 1. 05 9. 35 13. 58 12. 55 21. 74 20. 50 19. 69 15. 37 Cl .48 .83 2. 09 2. 21 3. 79 4. 10 11. 05 6. 21 NO, .73 1. 01 1. 10 1. 05 .81 1. 60 P0 4 . 27 Ca 22. 94 20. 77 18. 68 18. 06 17. 08 17. 16 20. 25 20. 50 Mr 4. 09 7. 27 7. 35 8. 03 6. 22 5. 72 4. 66 5. 38 Na 5. 14 | 5. 19 | 5.65 | 5.52 | 8.15 8. 09 6. 86 | 8.33 K 1. 75 1. 52 1. 57 SiOo 9. 40 7.78 J 9.09 J 9.03 J 8.54 11.44 5. 07 7. 05 AloOo 2. 01 .12 .45 Fe 2 0 3 1. 49 .05 .28 .35 .20 .43 .08 .13 M113O4 .11 Salinity, parts per million 100. 00 195 100. 00 200 100. 00 179 100. 00 203 100. 00 269 100 . 00 202 100. 00 146 100. 00 166 a For two analyses of Mississippi water, taken above and below Minneapolis, see J. A. Dodge, Tenth Ann. Rept. Geol. Nat. Hist. Survey Minnesota, 1882, p. 207. These analyses are given in the first edition of this book. Bailey Willis (Jour. Geology, vol. 1, 1893, p. 509) cites some imperfect analyses of the Missis- sippi and Missouri near St. Louis. Iowa Geol. Survey, vol. 6, 1896, p. 365, contains other analyses of Mississippi water, and also of Missouri, Cedar, Des Moines, Coon, Boyer, Wapsipiniccn, Skunk, Chariton, Grand, Nodaway , and West Nishnabotna rivers. These too are incomplete. The early analyses of Missis- sippi water by Avequin and by Jones are of no value for present purposes. Partial analyses, containing some useful data, are given in Report of the sewage and water board, New Orleans, 1903. These relate to the lower Mississippi near New Orleans. This table tells a definite story. The upper Mississippi is low in sulphates and chlorides, which tend to accumulate in the lower 76 THE DATA OF GEOCHEMISTRY. stream. The chlorides come in part from human contamination, a subject to be considered later; but more largely, together with sul- phates, from western tributaries, notably from the Missouri. At New Orleans, also, there is probably some “cyclic sodium” brought in rainfall from the Gulf of Mexico. On the whole, carbonates pre- dominate in the Mississippi water, with all else subordinate. The next table gives analyses of waters tributary to the upper Mississippi within the States of Minnesota and Wisconsin . 1 Analyses of waters tributary to upper Mississippi River. A. Lake Minnetonka. Analysis by W. A. Noyes, Geology of Minnesota, vol. 2, 1888, p. 311. B. Mille Lacs Lake. Analysis by J. A. Dodge, Geology of Minnesota, vol. 4, 1899, p. 38. C. Bigstone Lake. Analysis by C. F. Sidener, Thirteenth Ann. Rept. Geol. Nat. Hist. Survey Minne- sota, 1884, p. 98. Empties into Minnesota River. D. Heron Lake. Analysis by Noyes, Eleventh Ann. Rept. Geol. Nat. Hist. Survey Minnesota, 1882, p. 173. Empties into Des Moines River. E. Rock River at Luveme, Minnesota. A tributary of Sioux River. Analysis by Noyes, Geology of Minnesota, vol. 1, 1884, p. 550. F. Minnesota River at Shakopee, Minnesota. Mean analysis of 30 composite samples taken between September 24, 1906, and October 1, 1907. W. M. Barr, H. S. Spaulding, W. Van Winkle, R. B. Dole, C. Palmer, and W. D. Collins, analysts. Alkali determinations as corrected by Palmer. G. Chippewa River near Eau Claire, Wisconsin. Mean of 35 composites, September 14, 1906, to Sep- tember 12, 1907. Barr, Spaulding, and Van Winkle, analysts. H. Wisconsin River near Portage, Wisconsin. Mean of 24 composites, September 11, 1906, to May 17, 1907. Same analysts as under G. Analyses F, G, H are recalculated from the figures given by Dole in Water-Supply Paper 236. A B c D E F G H COb 58.81 59.03 20. 13 42.65 47.94 31.59 30. 49 31.43 S04 .88 34. 36 18.62 8.64 31. 26 18.09 18.74 Cl .72 .59 1.65 1.14 .44 1. 02 1.42 2.31 no 3 1.39 .43 . 78 .99 Ca 25.52 15. 25 8.00 20. 71 20. 51 17.81 16.80 15.44 Mg 7.23 10. 71 8.61 8.00 7.43 7.61 6.07 7.50 Na 1.03 6.68 6.69 2.94 3.31 4. 12 jlO. 46 | 8.93 K 2.32 2.24 1.01 1.32 .51 1. 15 Si0 2 4.37 2. 97 19.26 2.61 } .62 7.65 4. 99 15. 50 j 14.33 Fe 2 03 1.65 .29 3.21 .02 .39 .33 A1 2 0 3 .36 ) Salinity, parts per •million 100. 00 110 100. 00 144 100. 00 554 100. 00 272 100. 00 275 100. 00 480 100. 00 90 100. 00 98 i For analyses of several other Minnesota waters, see Water-Supply Paper U. S. Geol. Survey No. 193, 1907, p. 133. LAKES AND RIVERS. 77 The following table gives analyses of waters tributary to the Mis- sissippi in Illinois and Iowa: Analyses of tributaries in Illinois and Iowa. A. Rock River near Sterling, Illinois. Mean analysis of 36 composite samples taken between August 1, 1906, and July 31, 1907. W. D. Collins, analyst. Collins also gives a similar annual average for the river at Rockford. B. Illinois River ne ar Kampsville, Illinois. Mean of 36 composites, August 1, 1906, to July 31, 1907. Collins, analyst. He aIso~gives similar analyses for the river near Lasalle and Peoria. C. Kaskaskia River at Carlyle, Illinois. Mean of 34 composites, August 1, 1906, to July 31, 1907. Collins, analyst. A similar average is given for the river near Shelbyville. D. Cedar River near Cedar Rapids, Iowa. Mean of 37 composites, September 6, 1906, to September 17, 1907. W. M. Barr, H. S. Spaulding, and W. Van Winkle, analysts. E. Iowa River at Iowa City, Iowa. Mean of 36 composites, September 6, 1906, to September 16, 1907. Same analysts as under D. F. Des Moines River at Keosauqua, Iowa. Mean of 36 composites, September 10, 1906, to September 9, 1907. Same analysts as under D. Analyses A, B, and C are recalculated from the figures given by Collins in Water-Supply Paper 239; the others are from Dole, Water-Supply Paper 236. Collins also gives annual averages for the composition of the waters of Kankakee, Pox, Vermilion, Sangamon, Muddy, Embarrass, Little Wabash, and Cache rivers. In all, 19 rivers were studied, including the Mississippi. A B c D E F COs 48. 56 38.42 42. 13 44.80 42.17 34.96 23. 37 1.58 1.09 19.09 6.91 | 5.59 S04 9.34 16.30 13. 64 i3. 08 14. 70 Cl 2.06 5.82 2. 77 1.48 1. 47 no 3 1.42 1.67 1.92 1.35 1. 15 Ca 18. 30 18.24 18.86 20. 91 20.00 Mg 10.09 7. 76 8.02 6.97 6. 94 Na | 4.48 | 6.98 | 5.62 | 5.23 | 5.67 K Si0 2 5.60 4. 65 6.84 6. 10 7. 76 .14 7.24 .17 F62O3 .15 .16 .20 .08 Salinity, parts per million 100. 00 267 100. 00 267 100. 00 248 100. 00 228 100. 00 247 100.00 312 78 THE DATA OF GEOCHEMISTRY, In the following table I give analyses of waters which reach the Mississippi from the eastward by way of the Ohio . 1 For the Ohio itself I have found no satisfactory data. Analyses of waters tributary to Ohio River. A. Allegheny River at Kittanning, Pennsylvania. Mean analysis of 36 composite samples taken between September 13, 1906, and September 10, 1907. R. B. Dole, M. G. Roberts, and C. Palmer, analysts. B. Monongahela River at Elizabeth, Pennsylvania. Mean of 37 composites, August 25, 1906, to Septem- ber 2, 1907. Same analysts as under A. Dole also gives an annual average for the composition of Y oughio- gheny water. C. Muskingum River at Zanesville, Ohio. Mean of 27 composites, September 3, 1906, to September 13, 1907. Same analysts as under A. D. Miami River at Dayton, Ohio. Mean of 34 composites, September 16, 1906, to September 17, 1907. Dole, Roberts, Palmer, and Collins, analysts. E. East Fork of White River near Azalia, Indiana. Mean of 37 composites, September 12, 1906, to October 3, 1907. Barr, Spaulding, Van Winkle, Dole, Palmer, and Collins, analysts. F. West Fork of White River near Indianapolis, Indiana. Mean of 35 composites, September 8, 1906, to September 12, 1907. Barr, Spaulding, and Van Winkle, analysts. G. Wabash River at Vincennes, Indiana. Mean of 31 composites, September 9, 1906, to September 16, 1907. Same analysts as under F. H. Kentucky River at Frankfort, Kentucky. Mean of 36 composites, August 28, 1906, to September 4, 1907. Same analysts as under D . I. Cumberland River at Kuttawa, Kentucky. Mean of 34 composites, January 11, 1907, to January 11, 1908. Evans, Dole, Palmer, and Collins, analysts. Another average is given for the water near Nashville, Tennessee. J. Tennessee River near Gilbertsville, Kentucky. Mean of 33 composites, October 24, 1906 to October 24, 1908. Van Winkle, Dole, Palmer, and Collins, analysts. Another average is given for the water at Knoxville, Tennessee. All the analyses in this series are recalculated from the figures given by Dole in Water-Supply Paper 236, as corrected by the later alkali determinations of Palmer. A B C D E co 3 21.51 11. 47 24. 71 43. 64 47. 85 so 4 19. 55 42. 52 18. 36 13. 88 10. 58 Cl 16. 10 4. 12 17. 07 1. 42 1. 10 no 3 .82 2.32 .69 2. 98 1. 97 Ca 16. 10 15. 47 18. 36 20. 46 21. 51 Mg 3.46 2. 84 4. 06 8. 33 8. 11 Na 11. 04 8. 12 9. 39 2. 49 2. 75 K 2. 09 1.42 1. 28 .83 . 77 Si0 2 9. 09 10. 82 5. 98 5. 89 5. 29 Fe 2 0 3 .24 .90 .10 .08 .07 Salinity, parts per million 100. 00 87 100. 00 81 100. 00 244 100. 00 289 100. 00 279 F G H I J co 3 31. 76 34. 09 38. 51 40.57 34. 57 so 4 12. 88 16. 57 8. 32 7. 85 10. 74 Cl 17. 32 10. 84 2. 01 2. 43 2. 93 no 3 1. 36 1. 93 2. 51 1. 46 1. 17 Ca 16. 44 18. 37 21. 06 22. 67 18. 56 Mg 6. 44 6. 63 3. 71 3. 48 4. 00 Na | 10. 66 | 7.56 5. 82 4. 29 5. 08 K 1.41 2. 34 2. 83 Si0 2 3. 10 3. 92 16. 05 14. 59 19.54 Fe 2 0 3 .04 .09 .60 .32 .58 Salinity, parts per million 100. 00 450 100. 00 336 100. 00 104 100. 00 124 100.00 101 1 An analysis of Monongahela water by C. D. Howard and one of water from the Cumberland by N. T. Lupton are given in the first edition of this book (Bulletin 330). LAKES AND RIVERS. 79 For the largest tributary of the Mississippi — the Missouri — several analyses are available. They are given in the following table, together with analyses of its affluents . 1 Analyses of water from Missouri River and tributaries. A. Missouri River near Florence, Nebraska. Mean analysis of 36 composite samples taken between October 1, 1906, and October 14, 1907. Barr, Spaulding, Van Winkle, Dole, Palmer, and Collins, analysts. B. Missouri River near Kansas City, Missouri. Mean of 38 composites, October 4, 1906, to October 21, 1907. Same analysts as under A. C. Missouri River near Ruegg, Missouri. Mean of 36 composites, September 24, 1906, to October 6, 1907. Same analysts as under A. D. North Platte River at North Platte, Nebraska. Mean of 29 composites, September 10, 1906, to June 30, 1907. Barr, Spaulding, and Van Winkle, analysts. E. Platte River at Fremont, Nebraska. Mean of 33 composites, October 10, 1906, to November 2, 1907. Barr, Van Winkle, Dole, Palmer, and Collins, analysts. Another series of analyses of the water at Columbus is also given. An analysis of the Platte at Greeley, Colorado, is given on p. 61, ante, together with some of its tributary, Cache la Poudre River. F. Laramie River 20 miles above Laramie, Wyoming. Average of three analyses by E. E. Slosson, Bull. Wyoming Exper. Sta. No. 24, 1895. G. Laramie River 50 miles below Laramie. Analysis by E. E. Slosson, loc. cit. Slosson also gives analyses of Popo Agie and Little Goose creeks. Another analysis of the Laramie is printed in Fifth Rept. Bur. Soils, U. S. Dept. Agr., 1903. H. Yellowstone Lake. Analysis by J. E. Whitfield, Bull. U. S. Geol. Survey No. 47, 1888. This bulletin also gives analyses of Firehole and Gardiner rivers. Analyses A to E are recalculated from Dole’s Water-Supply Paper 236, with potassium determinations communicated by Palmer. A B c D E F G H co 3 22. 42 24. 23 25. 63 24. 13 29. 43 27. 35 19. 59 20. 93 so 4 37.69 32. 74 30. 44 32. 77 22. 18 11. 16 37. 48 7. 12 Cl NO, 1. 99 .40 3. 15 .54 3. 52 .85 3. 15 .53 2. 18 .33 3. 11 6. 32 7. 96 Ca 14. 58 15. 04 15. 22 15. 05 15. 80 13. 75 15. 07 7. 29 Mg 4. 48 4. 37 4. 68 4. 37 3. 67 2. 45 5. 10 .25 Na 9. 64 9. 22 9. 07 110. 68 8. 06 7. 34 8. 82 13. 22 K nh 4 1. 70 1. 50 1. 90 / 2. 42 .85 1. 96 3. 99 . 34 Si0 2 A1 2 0 3 6. 95 8. 97 8. 49 8. 98 15. 80 31. 73 4. 54 35. 51 3. 39 Fe,0, .15 .24 .20 .34 .13 1 2.26 } 1. 12 J ) 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 454 426 346 426 302 212 429 118 In all but three of these waters sulphates predominate over car- bonates, and calcium is less conspicuous than in the analyses preceding this group. The high silica of the Yellowstone Lake and the upper Laramie is also noticeable. 1 Two analyses of water from the Missouri, not used here, are given in the first edition of this book. Another analysis by F. W. Traphagen is cited in E. W. Hilgard’s Soils, p. 23, but the point of collection is not named. 80 THE DATA OF GEOCHEMISTRY. For one other tributary of the Missouri a particularly interesting group of analyses is at hand. Kansas or Kaw River, with its chief affluents, has been studied by E. H. S. Bailey and his assistants , 1 whose data, reduced as usual, are given in the next table. The locali- ties mentioned are all in the State of Kansas, and the arrangement of the streams is from the west, eastward. Analyses of water from Kansas River and its tributaries. A. Smoky Hill River at Lindsborg. Mean of 28 analyses of composite samples of water taken between November 27, 1906, and November 29, 1907. F. W. Bushong and A. J. Weith, analysts. B. Saline River at Sylvan Grove. Mean of 34 composite samples taken between November 27, 1906, and November 29, 1907. Analyses by Bushong. C. Solomon River at Beloit. Mean of 32 composite samples taken between December 1, 1906, and De- cember 5, 1907. Bushong and Weith, analysts. D. Republican River at Junction. Mean of 25 composite samples taken between November 26, 1906, and September 10. 1907. Bushong and Weith, analysts. E. Big Blue River at Manhattan. Mean of 34 composite samples taken between December 19, 1906, and December 20, 1907. Bushong and Weith, analysts. F. Delaware River at Perry and Valley Falls. Mean of 27 composite samples taken between January 4 and November 29, 1907. Bushong and Weith, analysts. G. Kansas River at Holliday. Mean of 72 composite samples taken between December 29, 1906, and December 31, 1908. Two years’ average. Analyses by F. W. Bushong, A. J. Weith, and W. L. Sippy. Analyses of several other tributaries of the Kansas are also given in the paper. A B C D E F G co 3 14. 40 6. 02 26. 17 34. 36 35. 53 39. 47 31. 78 so 4 26. 87 18. 26 19. 50 12. 56 12. 32 12. 17 15. 14 Cl 21. 61 38. 57 12. 09 7.11 5. 89 3. 85 10. 18 no 3 .21 .03 .54 . 71 .64 1. 07 .57 Ca 12. 93 5. 03 16. 61 16. 35 18. 74 20. 78 18. 12 Mg : 2. 41 1. 98 2. 89 3. 32 3. 92 4. 75 3. 98 Na, K 18. 26 28. 97 15. 52 13. 50 12. 32 9. 79 12. 66 Si0 2 3. 18 1. 07 6. 32 11. 38 9. 52 6. 82 7. 19 Fe 2 0 3 .13 .07 .36 .71 1. 12 1. 30 .38 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million. . . 882 2, 624 554 422 357 337 403 The two westernmost of these streams flow from a relatively arid region and are characterized by high salinity. They are peculiarly poor in carbonates but rich in sodium and chlorine, conditions which may be correlated with the great abundance of salt in Kansas. In the Solomon River carbonates begin to predominate; and in the easternmost rivers of the group there is a close approximation in chemical character to some streams of the Atlantic slope. Kansas River itself represents a blending of all the waters which flow into it . 2 1 U. S. Geol. Survey Water-Supply Paper No. 273, 1911. Some earlier analyses by Bailey and Franklin are cited in the previous editions of this work. 2 Partial analyses of about 50 streams in Oklahoma may be found in Water-Supply Paper U. S. Geol. Survey No. 148, 1905. A paper by J. H. Norton on the drainage of Richland Creek, Arkansas, appeared in Jour. Am. Chem. Soc., vol. 30, 1908, p. 1186. An analysis of water from the Wakarusa River is cited in the second edition of this work. LAKES AND RIVERS. 81 Two analyses of water from Arkansas River have already been cited, and need not be repeated here. Other analyses of this river and its tributaries, together with Osage and Red rivers will end this summary of the Mississippi Basin . 1 Analyses of water from the Arkansas and other rivers. A. Osage River, at Boicourt, Kansas. Mean of 33 analyses of composite samples of water taken between November 29, 1906, and November 30, 1907. F. W. Bushong and A. J. Weith, analysts. This stream is a tributary of the Missouri. B. Arkansas River at Deerfield, Kansas. Mean of 26 composite samples taken between December 11, 1906, and December 2, 1907. Bushong and Weith, analysts. C. Arkansas River near Great Bend, Kansas. Mean of 33 composite samples taken between November 26, 1906, and December 7, 1907. Bushong and Weith, analysts. D. Arkansas River at Arkansas City, Kansas. Mean of 27 composite samples taken between December 7, 1906, and December 10, 1907. Bushong and Weith, analysts. E. Arkansas River at Little Rock, Arkansas. Mean of 22 composite samples taken between November 1, 1906, and October 24, 1907. Barr, Spaulding, Van Winkle, Dole, Palmer, and Collins, analysts. Recal- culated from Water-Supply Paper No. 236. F. Cimarron River at Englewood, Kansas. Mean of 30 composite samples taken between November 30, 1906, and November 30, 1907. Bushong and Weith, analysts. A tributary of the Arkansas. G. Neosho River at Emporia, Kansas. Mean of 35 composite samples taken between December 5, 1906, and December 5, 1907. Bushong and Weith, analysts. A tributary of the Arkansas. An earlier, single analysis of Neosho water by C. F. Gustavsen appears in Kansas Univ. Sci. Bull., vol. 2, p. 243, 1903. H. Red River near Shreveport, Louisiana. Mean of 34 composite samples taken between March 19, 1906, and March 19, 1908. Dole, Palmer, Collins, and Evans, analysts. Recalculated from Water-Supply Paper 236, with later alkali determinations by Palmer. All these analyses except E and H are taken from Water-Supply Paper No. 273. In this paper there are also analyses of the Marmaton, Walnut, Medicine Lodge, Chikaskia, Verdigris, Fall, Cottonwood, and Spring rivers, with some minor streams, all in Kansas. A B C D E F G H co 3 37. 26 7. 55 9. 95 12. 33 11. 89 11.42 39.02 13. 01 so 4 12. 31 54. 70 47. 19 19. 18 15. 19 11. 87 10. 61 25. 65 Cl 3. 41 4. 77 8. 72 29. 03 33. 17 37. 65 2. 25 22. 16 no 3 1. 20 .21 .17 .18 .33 .13 1. 09 .07 Ca 22. 90 12. 31 13. 13 9.44 8. 99 6. 93 20. 60 13. 56 Mg 4. 10 4. 11 3. 52 2. 39 2. 13 2. 57 4. 05 3. 12 Na K | 9.56 jl4. 24 |14. 71 |24. 15 123. 53 |26. 91 | 7.80 15. 74 .91 Si0 2 J 8.20 j 1.92 J 2.46 J 3.08 * 4.57 J 2.87 13. 77 5. 49 Fe 2 0 3 1. 06 .19 .15 .22 .20 .15 .81 .29 Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 293 1, 510 1, 136 1, 006 630 1, 323 320 561 i Two analyses by R. N. Brackett of water from the Arkansas are given in Ann. Rept. Arkansas Geol. Survey, 1891, vol. 2, pp. 159, 160. 97270°— Bull. 616—16 6 82 THE DATA OF GEOCHEMISTRY. SOUTHWESTERN RIVERS. A few of the rivers of the southwestern United States have been studied with much care. The following analyses represent this group. 1 Analyses of water from southwestern rivers. A. Brazos River at Waco, Texas. Mean analysis of 30 composite samples taken between December 14, 1906, and November 19, 1907. Barr, Spaulding, Van Winkle, Dole, Palmer, and Collins, analysts. Recalculated from Water-Supply Paper 236, with later alkali determinations by Palmer. B. Colorado River of Texas, at Austin. Mean of 36 composites, August 1, 1905, to July 27, 1906. W. H. Heileman, analyst, Water-Supply Paper 236. C. Rio Grande at Laredo, Texas. Mean of 37 composites, August 1, 1905, to August 2, 1906. Heileman, analyst, loc. cit. D. Rio Grande at Mesilla, New Mexico. Average composition for an entire year, June, 1893, to June, 1894. Analyses by Arthur Goss, Bull. New Mexico Agr. Exper. Sta. No. 34, 1900. This bulletin also contains analyses of water from Animas River, Santa Fe River, and Rio Bonito. E. Pecos River, New Mexico. Average of six samples analyzed by Goss, loc. cit. F. Colorado River at Yuma, Arizona. Average of seven composite samples, covering collections made between January 10, 1900, and January 24, 1901. Analyzed by R. H. Forbes and W. W. Skinner, Bull. Univ. Arizona Agr. Exper. Sta. No. 44, 1902. The average composition of the water during a year. G. Gila River at head of Florence canal, below The Buttes, Arizona. Average of four analyses by Forbes and Skinner representing twenty-one weekly composites. Samples taken between November 28, 1899, and November 5, 1900. H. Salt River at Mesa, Arizona. Average of six analyses covering forty weekly composites of water taken between August 1, 1899, and August 4, 1900. Analyses by Forbes and Skinner, loc. cit. Salt River and the Gila are tributaries of the Colorado. Forbes and Skinner report their silica as the silicate radicle SiC> 3 . This is reduced to SiC >2 in the table. A B C D E F G H co 3 7. 09 28. 60 11. 55 17. 28 1.54 13. 02 12. 10 9. 61 so 4 25. 49 12. 48 30. 10 31. 33 43. 73 28. 61 16. 07 8. 29 Cl 30. 87 17. 52 21. 65 13. 55 22. 56 19. 92 29. 78 41. 56 no 3 .20 Ca 11. 06 15. 45 13. 73 14. 78 13. 43 10. 35 8. 03 7. 15 Mg 1. 74 5. 14 3. 03 2. 05 3. 62 3. 14 2. 52 2. 69 Na 20. 83 13. 07 14. 78 14. 43 14. 02 19. 75 24. 53 26. 38 K .67 1. 50 .85 1. 95 .77 2. 17 2. 31 1. 38 Si0 2 2.01 5. 32 3. 83 l 1 3. 04 4. 66 2. 94 A1 2 0 3 1 1 4. 63 l .33 Fe 9 0q .04 > . 92 f .48 J x 2, o J J 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 1, 136 321 791 399 2, 384 702 1, 023 1, 234 These waters are characterized, as is evident on inspection of the table, by high salinity, the predominance of alkaline sulphates and chlorides, and a deficiency of carbonates and of lime. From figures given by Forbes I have computed that the Colorado carries to the Gulf of California annually, in solution, 13,416,400 metric tons of salts, or about 59.6 metric tons from each square mile of its basin. i An analysis of Rio Grande water by O. Loew is given in Rept. U. S. Geog. Surveys W. 100th Mer., vol. 3, 1875, p. 576. In the annual report of the same Survey for 1876 Loew gives an analysis of water from Virgin River, a tributary of the Colorado. For two analyses of the Pecos see B. S. Tilson, Bull. Geol. Survey Texas No. 2, 1910. Analyses of Rio Grande water by Fraps and Tilson are cited in Circular 103, Office Exper. Sta., U. S. Dept. Agr., 1911. LAKES AND RIVERS. 83 RIVERS OF CALIFORNIA. For the river waters of California the data are now very abundant, but only a small part of them can be utilized here. A number of individual analyses are to be found in the former editions of this book; 1 the following table is recalculated from the figures reported by W. Van Winkle and F. M. Eaton in Water-Supply Paper 237, 1910. In that paper the average composition of a river water is ascertained by many analyses of composite samples, representing daily collections, as was done in the investigations under Dole and Collins which have already been freely cited. The composition of each water is thus determined for a sufficiently long time to give the figures real significance in geochemical research. Van Winkle and Eaton, by this general method, studied 37 rivers of California. Analyses of water from rivers of California. A. Russian River near Ukiah. Mean analysis of 37 composite samples taken between December 31, 1907, and December 31, 1908. B. Sacramento River above Sacramento. Mean of two series of analyses covering the years 1906 and 1908. Potassium was separately determined during the first half of 1906, and the same is true of total Fe 203 +Al 2 03 . In recalculating, these determinations are assumed to be fair averages. Van Winkle and Eaton also give annual averages for Feather, Yuba, and American rivers and Cache Creek, all tributaries of the Sacramento. C. San Joaquin River at Lathrop. Mean of two series, 1906 and 1908, recalculated as in the case of the Sacramento. Similar averages for one year or less are given for the tributary rivers Mokelumne, Stanislaus, Tuolumne, Merced, and Kern. D . Salinas River at Paso Robles. Mean of 30 composites taken in 1908. From about July 18 to October 1 the river bed was dry. Data are given for several tributaries of the Salinas. E. Santa Maria River 25 miles above Santa Maria. Mean of 36 composites covering the year 1906. K and total R2O3 were only determined during the first half year. F. Santa Ynez River at Santa Barbara. Mean of 33 composites covering the year 1906. K and R 2 O 3 determined during the first half year only. G. San Gabriel River near Rivera. Mean of 37 composites covering the year 1908. Another average is given for the river at Azusa. H. Santa Ana River above Mentone. Mean of two series, 1906 and 1908. K and R2O3 determined during the first half of 1906. Another annual average is given for the river near Corona. A B c D E F G H co 3 39. 07 30. 14 18. 43 30. 66 5. 82 19. 33 40. 54 35. 78 so 4 10. 81 12. 21 17. 41 21. 35 58. 35 42. 58 12. 62 11. 34 Cl 4. 70 5. 79 20. 62 8. 59 4. 89 3. 71 3. 22 3. 70 N0 3 . . 77 .48 .54 . 16 . 73 . 50 Ca 14. 61 11. 45 10.13 13. 21 14. 07 14. 98 21. 04 17] 02 Mg 7. 62 5. 59 4. 82 6. 17 6. 19 6. 68 4. 59 4. 00 Na \10. 17 9. 78 15. 81 112. 99 8. 94 8. 10 \ 8.41 10. 67 K / 1. 68 1. 08 / . 37 . 51 / 1. 33 Si0 2 ' 12. 07 19. 12 9. 38 6. 82 1. 12 3. 56 8. 79 13*. 68 ALO3 3. 35 1. 56 .24 .53 1. 86 Fe 2 0 3 .18 .41 .22 .05 .01 .02 .06 .12 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 145 118.5 183 448 2, 412 714 246 152 1 Clear Lake, analysis by T. Price, cited in Water-Supply Paper U. S. Geol. Survey No. 45, 1901. Feather River, by E. W. Hilgard, Rept. Agr. Exper. Sta., Univ. California, 1898-1901. San Lorenzo River, by A. Seidell, Field Operations Bur. Soils, U. S. Dept. Agr., 1901. Santa Clara River, by B. E. Brown, same reference as the preceding. Santa Ynez River and three of its tributaries, by J. A. Dodge, Water-Supply Paper U. S. Geol. Survey No. 116, 1904. Other analyses, by H. G. Kelsey, appear in University of Cali- fornia, Rept. Coll. Agric., 1882. 84 THE DATA OF GEOCHEMISTRY, THE COLUMBIA RIVER BASIN. The waters of Oregon and Washington have been studied with much thoroughness by W. Van Winkle 1 and a selection from among his abundant data is given in the following tables. The Columbia and its tributaries come first. Analyses of water from Columbia and Snake rivers. A. Columbia River at Northport, Washington. Mean of 37 analyses of composite samples of water taken between February 1, 1910, and January 31, 1911. B. Columbia River at Pasco, Washington. Mean of 37 composite samples taken between February 1, 1910, and January 31, 1911. C. Columbia River at Cascade Locks. Mean of 30 composite samples taken between March 13 and December 31, 1910, and 37 composite samples taken between August 11, 1911, and August 14, 1912. Nearly two years’ average. D. Snake River near Weiser, Idaho. Mean of 37 composite samples taken between August 11, 1911, and August 14, 1912. E. Snake River at Burbank, Washington. Mean of 33 composite samples taken between March 13, 1910, and January 31, 1911. A B c D E co 3 42. 38 42. 81 36. 15 31. 02 31. 95 so 4 14. 12 13. 08 13. 52 16. 45 16. 37 Cl . 71 . 84 2. 82 7. 99 6. 31 no 3 . 27 . 16 . 49 . 28 . 41 Ca 21. 19 21. 40 17. 87 15. 51 14. 81 Mg 5. 53 5. 35 4. 38 4. 52 4. 37 Na | 5.53 | 7.14 8. 12 10. 34 | 10.91 K 1. 95 1. 64 Si0 2 R 2 0 3 ‘ 10.24 .03 9. 16 .06 14. 62 .08 12. 22 .03 14. 81 .06 Salinity, parts per million. . . .• 100. 00 85 100. 00 84 100. 00 92. 4 100. 00 213 100. 00 128 i Water-Supply Papers U. S. Geol. Survey Nos. 339, 363, 1914. LAKES AND RIVERS, 85 Analyses of water from tributaries to the Columbia. F. Spokane River at Spokane, Washington. Mean of 35 composite samples taken between February 1, 1910, and January 31, 1911. G. Yakima River at Prosser, Washington. Mean of 37 composite samples taken between February 1, 1910, and January 31, 1911. H. Owyhee River near Owyhee, Oregon. Mean of 37 composite samples taken between August 11, 1911, and August 14, 1912. I. Grand Ronde River at Elgin, Oregon. Mean of 37 composite samples taken between August 11, 1911, and August 14, 1912. J. Umatilla River near Umatilla, Oregon. Mean of 36 composite samples taken between August 11, 1911, and August 14, 1912. Analyses are given by Van Winkle for samples collected at two other points also. K. John Day River at McDonald, Oregon. Mean of 37 composite samples taken between August 11, 1911, and August 14, 1912. Analyses are given for the water at Dayville also. L. Deschutes River at Moody, Oregon. Mean of 34 composite samples taken between August 21, 1911, and July 25, 1912. Analyses are given for the water at Bend also. M. Willamette River at Salem, Oregon. Mean of 37 composite samples taken between August 11, 1911, and August 14, 1912. Van Winkle gives analyses, most of them annual averages, for 13 other rivers of the Columbia Basin. F G H I J K L M co 3 35. 94 32. 30 31. 24 30.03 31. 49 39. 79 31. 81 28. 32 so 4 14. 43 17. 39 15. 85 6. 12 12. 71 8. 51 5. 68 8. 19 Cl . 94 4. 30 5. 89 1. 85 5.18 1. 92 2. 38 4. 21 N0 3 . 36 . 28 . 29 . 86 .62 . 78 .75 . 79 Ca 17. 19 13. 25 11. 78 11. 55 12. 71 14. 18 9. 66 11. 73 Mg 5. 62 5. 05 2. 90 3. 23 3. 65 5. 39 3. 06 3. 09 Na | 8. 28 jll. 59 15. 85 9. 00 12. 15 9. 22 12. 50 8. 41 K 2. 08 2. 31 2. 65 1. 70 2. 28 1. 77 Si0 2 17. 19 15. 73 14. 04 34. 64 18. 78 18. 44 31. 81 33. 18 Fe 9 0q .05 .11 .08 .41 .06 .07 .07 .31 Salinity, parts per million 100. 00 64 100. 00 121 100. 00 221 100. 00 87 100. 00 181 100. 00 141 100. 00 88 100. 00 45 According to Van Winkle the Columbia carried in solution past Cascade Locks, in 1910, 21,638,000 short tons of dissolved matter, and in 1911-12, 17,000,000 tons. This, for a drainage area of 239,600 square miles, is equivalent to 90.3 and 71 tons per square mile; an average of 80.6, or 73 metric tons. 1 Similar estimates are given for each of the tributaries. 1 For earlier single analyses of the Columbia, Snake, Willamette, and Powder rivers, see the second edition of this work, p. 78. Powder River is a tributary of the Snake. 86 THE DATA OF GEOCHEMISTRY. OTHER NORTHWESTERN RIVERS. In the next table analyses are given of waters from Oregon and Washington, with one from Alaska. Except when otherwise stated, the analyses are by W. Van Winkle , 1 and represent annual averages. Analyses of northwestern waters. A. Yukon River at Eagle, Alaska. Single analysis by G. Steiger. Reported by F. W. Clarke, Jour. Am. Chem. Soc., vol. 27, 1905, p. 111. B. Skagit River at Sedro Woolley, Washington. Mean of 37 analyses of composite samples of water taken between February 1, 1910, and January 31, 1911. C. Chehalis River at Centralia, Washington. Mean of 35 composite samples taken between February 1, 1910, and January 31, 1911. D. Rogue River near Tolo, Oregon. Mean of 34 composite samples taken between September 10, 1911, and August 14, 1912. E. Umpqua River near Elkton, Oregon. Mean of 22 composite samples taken between August 1, 1911, and August 15, 1912. F. Goose Lake, Oregon. Single analysis by Van Winkle. G. Lost River, Klamath County, Oregon. Single analysis by A. L. Knisely. Ann. Rept. Irr. and Drainage Investigation, U. S. Dept. Agr., 1904, p. 264. H. Crater Lake, Oregon. Single analysis by N. M. Finkbiner. Cited by Van Winkle in W. S. Paper 363, p. 43. Included here on account of its analogy to the river waters of Oregon, although it properly belongs in the chapter on closed basins. 2 A B c D E F G H co 3 46. 16 30. 78 26. 06 28. 83 28. 66 34. 30 52. 64 20. 62 so 4 10. 75 17. 71 10. 93 6. 32 8. 43 4. 92 3. 37 13. 75 Cl .41 1. 95 8. 88 2. 16 4. 85 10.92 1. 46 13. 75 no 3 . 52 . 18 .40 . 49 . 16 .47 PCX, . 12 .01 Ca 22. 21 17. 06 12. 12 11. 11 12. 80 1. 96 14. 12 8. 88 Mg 4. 71 3. 67 3. 24 2. 62 3. 58 .22 12. 06 3.50 Na 6. 14 1 7.78 111. 10 9. 41 9. 24 38. 23 2. 78 13. 75 K Trace. / / 2. 00 2. 59 3. 71 10. 78 2. 75 Si0 2 7. 78 20. 30 27. 31 37. 00 29. 14 5. 46 10. 42 22.50 Fe 2 0 3 A1 2 0 3 1. 84 .23 .18 .15 .22 Trace. } 2. 37 .02 ) 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 98 46 59 65 62 916 220 80 1 See Water-Supply Papers U. S. Geol. Survey Nos. 339 and 363, 1914. 2 Van Winkle also gives analyses of waters from Wood Creek, Cedar, and Green rivers in Washington, and of Link, Wood, and Siletz rivers in Oregon. For an earlier analysis of water from Cedar River, see H. G. Knight, Washington Geol. Survey, vol. 1, p. 285, 1901. Analyses of water from Lower Klamath Lake are given in U. S. Dept. Agr. Field Oper. Bur. Soils, 1908, p. 1412. LAKES AND RIVERS. 87 THE SASKATCHEWAN SYSTEM. This complex river system comprises a number of important branches, which finally unite in the Nelson River and empty into Hudson Bay. The following analyses represent waters from this great drainage basin: Analyses of waters from Saskatchewan system. A. Red River of the North at Fergus Falls, Minnesota. Analysis by W. A. Noyes, Eleventh Ann. Rept. Minnesota Geol. Nat. Hist. Survey, 1884, p. 173. B . Red River of the North at St. Vincent, Minnesota, near the Canadian boundary. Analysis by W. A. Noyes, op. cit., p. 172. C. Red River of the North below the Assiniboine. D. Assiniboine River above its junction with the Red. Analyses D and E by F. D. Adams, Rept. Progress Geol. Survey Canada, 1878-79, p. 10 H. E. Nelson River near its mouth. F. Hayes River opposite York Factory. This stream enters Hudson Bay near the Nelson. Analyses F and G by W. Dittmar, Rept. Progress Geol. Survey Canada, 1879-80, p. 77 C. A B c D E F co 3 32. 52 41. 20 31. 47 39. 70 16. 78 50. 36 so 4 25. 56 15. 71 22. 06 16. 52 41. 85 Cl .69 4. 89 8. 78 5. 58 4. 68 3. 08 PCL . 19 no 3 . 28 Ca 30. 39 17. 55 12. 89 13. 59 15. 91 21. 88 Ms 8. 23 7. 99 7. 72 5. 65 5. 24 Na 1. 97 5. 64 9. 67 11. 08 6. 22 4. 22 K 1. 19 1. 37 1. 18 1. 16 .97 1. 37 Li . 02 Si0 2 . 60 4. 57 5. 72 4. 41 7. 30 11. 48 (ALFebO, 7. 08 .35 .24 .24 .64 2. 37 Salinity, parts per million 100. 00 202 100. 00 284 100. 00 551 100. 00 509 100. 00 180 100. 00 115 88 THE DATA OF GEOCHEMISTRY. The following table gives analyses of the Bow River and its tribu- taries, the Bow being the main western branch of the Saskatchewan. All these streams are in the Alberta district, Northwest Territory, Canada. The analyses were made by F. G. Wait . 1 The samples were collected at low water. Analyses of water from Bow River and tributaries. H. Bow River at Calgary. I. Elbow River at Calgary. J. Highwood River at High River. K. Fish Creek at McLeod Trail. L. Sheep River near Dowdney. H I J K L CO, 48. 21 44. 66 47. 78 53. 57 45. 55 so 4 14. 69 18. 80 13. 22 5. 59 17. 13 Cl . 94 . 56 . 65 . 51 . 57 Ca 25. 23 24. 39 24. 48 18. 82 23. 69 Mg 6. 95 6. 55 6. 23 7. 57 6. 32 Na 2. 42 2. 77 3. 28 7. 14 3. 92 K Trace. . 42 Trace. 1. 34 . 43 Si0 2 1. 56 1. 85 4. 36 5. 46 2. 39 Fe 2 0 3 Trace. Trace. Trace. Trace. Trace. Salinity, parts per million 100. 00 128 100. 00 217 100. 00 183 100. 00 238 100. 00 209 SUMMARY FOR NORTH AMERICA. If now we look back over the analyses of North American rivers, we shall see that, in spite of all differences, certain general tendencies are manifest. In the first place, practically all the waters from east of the Missouri River, with one or two minor exceptions, are waters in which carbonates are largely in excess of sulphates and chlorides, and calcium is the dominating metal. The same rule holds for the extreme northern and northwestern rivers; but the western tributaries of the Missouri, in general, tell a different story. So also do the waters of New Mexico and Arizona. Here sulphates are in excess of carbonates, and calcium, although sometimes domi- nant, is not always so. In short, where the rainfall is abundant and the soil is naturally fertile, carbonate waters are the rule; in arid regions sulphates and chlorides prevail. This statement applies to the evidence now in hand, and must not be construed too sweepingly. We are dealing not with invariable laws, but with tendencies. The condition thus indicated is probably the outcome of various causes, but one of the latter is easily found. In a fertile region organic matter is abundant and great quantities of carbonic acid are 1 Rept. Geol. Survey Canada, new ser., vol. 9, 1878, pp. 39-45 R. LAKES AND RIVERS. 89 generated by its decay. This carbonic acid, absorbed by the ground water of the soil, acts as a solvent of mineral matter, and carbonates are carried into the streams more abundantly than other salts. In arid regions there is less organic decomposition, less carbonic acid, and a smaller proportion of carbonates is found. Water from a swamp or forest is very different from water which has leached a desert soil. In the Kansas River and its tributaries the passage from one set of conditions to the other is clearly apparent. Western Kan- sas is relatively arid, and the western branches of the river are poor in carbonates. Eastern Kansas is fertile, and the eastern affluents reflect its character. It must be borne in mind, however, that we are now considering relative proportions of substances and not absolute amounts. The lower course of a stream is a blend of many waters; and the change from one type to another does not necessarily imply that anything has been lost. Precipitation may have taken place, but in many cases the transformation from sulphate to carbonate is probably due to an overwhelming influx of the latter. The Missis- sippi itself, in its course southward, must receive carbonates more freely than sulphates; and its final character as it enters the Gulf of Mexico should be that of a carbonate water. So much at least can be safely inferred from the data already in hand. To small streams, it must be remembered, these considerations do not always apply. Local conditions are operative in such cases, and a river issuing from a region rich in gypsum, or fed by brooks affected by beds of pyrite, may have a sulphate character quite independent of the climatic influences which otherwise seem to rule. The local peculiarities of river water have been the subject of a considerable number of geochemical and hydrochemical investiga- tions, some of which will be noticed later. In general it may be said that a water at or near its source reflects in some measure the com- position of the rocks from which it rises. We have already seen the remarkable uniformity of character displayed by the rivers of the South Atlantic and eastern Gulf States. The waters of Illinois and Iowa, flowing through a rich agricultural area, underlain by sedi- mentary rocks exclusively, show a similar uniformity of composi- tion. Water from limestone is rich in lime, that from dolomite con- tains more magnesia, that from granite is characterized by rela- tively higher silica and alkalies. In small streams these resemblances appear quite clearly; in large rivers the commingling of the tribu- taries tends to produce an average composition which may be called that of a normal water. The great continental rivers resemble one another much more nearly than do their component branches. 90 THE DATA OF GEOCHEMISTRY. RIVERS OF SOUTH AMERICA. The river waters of South America, except in British Guiana, the Argentine Republic, and, Brazil, seem to have received very little attention from chemists. A. Muntz and V. Marcano 1 have described certain waters, from unnamed tributaries of the Orinoco and Amazon, which are colored nearly black by organic acids but contain not over 16 parts per million of mineral matter, and from which lime is prac- tically absent. These peculiarities are shared to some extent, although not so strikingly, by certain river waters of British Guiana, which are brown in color, low in salinity, and rich in organic matter. Fourteen of these waters have been analyzed by J. B. Harrison and K. D. Reid, 2 from whose table the following selection has been made. Their data are reduced here to the usual standard form, with normal carbonates and with organic matter omitted. The color is supposed to be due to organic compounds of iron, and the proportion of iron found, here reported as Fe 2 0 3 , is unusually large. As stated here the analyses represent the anhydrous inorganic matter which the waters could ultimately deposit. Analyses of waters from British Guiana. A. Barima River above Eclipse Falls. B. Waini River above First Falls. C. Essequibo River above Wataputa Falls. D. Demerara River above Malalli Falls. Another analysis of water taken in time of drought is also given. E. Courantyne River: F. Potaro River, above Tumatumari Falls. Analyses are also given of the Barama, Cuyuni, Puruni, Mazaruni, Rupununi, Mahaica, and Berbice rivers, and of Abary Creek. A B C D E F co 3 22. 12 28. 40 15. 74 12. 84 22. 14 25. 89 so 4 1. 39 .92 5. 65 1. 15 1. 22 1. 89 Cl 6. 45 6. 50 3. 36 10. 32 6. 86 2. 88 no 3 .51 .13 1. 11 .97 .30 2.00 10. 21 5. 45 3. 84 .38 5. 16 2. 25 Mg 4. 01 3. 02 2. 96 2. 65 2. 39 .97 Na 2. 67 12. 88 6. 97 10. 93 8. 75 18. 14 K .08 1. 88 .54 1. 69 2. 65 1. 26 Si0 2 43. 43 25. 04 52. 80 55. 92 41. 90 38. 54 Fe 2 0 3 9. 13 15. 78 7. 03 3. 15 8. 63 6. 18 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 Salinity, parts per million 78 45 30 73 40 44 The very high silica and generally high sodium in these waters suggest that they emerge from areas of crystalline rocks. The high proportion of chlorine, however, with some of the sodium, may be due to cyclic salt, the saline content of rainfall. 1 Compt. Rend., vol. 107, 1888, p. 908. See also J. Reindl, Natur. Wochenschr., vol. 20, 1905, p. 353. 2 Official Gazette, Georgetown, Demerara, July 26, 1913. LAKES AND RIVERS. 91 In the next table I give the available data for the Amazon and some of its tributaries. Analyses of water from Amazon River and tributaries. A. The Amazon between the Narrows and Santarem. Analysis by P. F. Frankland, cited by T. Mel- lard Reade in Evolution of earth structure. B. The Amazon at Obidos. Mean of two analyses by F. Katzer. See Grundziige der Geologie des unteren Amazonasgebietes, Leipzig, 1903. Katzer estimates that the Amazon carries annually past Obidos 618,515,000 metric tons of dissolved and suspended matter. C. The Xingu. Analysis by Katzer, loc. cit. D. The Tapajos. Analysis by Katzer, loc. cit. Katzer also gives analyses of water from Parana-mirim, the Maecuru, the Itapacurd-mirim, and several fresh-water lakes or lagoons. A B c D CO, 34. 75 24. 15 26. 78 29. 60 so 4 7. 37 2. 26 10. 57 7. 39 Cl 3. 85 6. 94 6. 96 5. 77 Ca 21. 12 14. 69 15. 77 16. 84 Mg 2. 57 1. 40 3. 92 3. 60 Na 1. 94 4. 24 2. 08 1. 80 K 2. 31 4. 76 4. 18' 3. 67 Si0 2 18. 80 28. 59 21. 15 24. 02 (Al,~Fe),0, 7. 29 12. 97 8. 59 7. 31 Salinity parts per million 100. 00 59 100. 00 37 100. 00 45 100. 00 38 From the southern parts of South America the following waters have been analyzed: Analyses of water from rivers in southern part of South America. A. River Plata 5 miles above Buenos Aires. Analysis by J. J. Kyle, Chem. News, vol. 38, 1878, p. 28. B. River Plata near Buenos Aires. Analysis by R. Schoeller, Ber. Deutsch. chem. Gesell., vol. 20, 1887, p. 1784. Water possibly affected by tidal contamination. For other data relative to the Plata and the Mercedes, see M. Puiggari, An. Soc. cient. Argentina, vol. 13, p. 49, 1882. C. The Parana 5 miles above its entry into the Plata. Analysis by Kyle, loc. cit. D. The Uruguay midstream opposite Salto. Analysis by Kyle, loc. cit. E. The Uruguay above Fray Bentos. Analysis by Schoeller, loc. cit. F. Rio Negro above Mercedes. Analysis by Schoeller, loc. cit. An analysis of Rio Negro by Will is cited by S. Rivas, An. Soc. cient. Argentina, vol. 1, 1877, p. 326. G. Colorado River, Argentina. Analysis by Kyle, An. Soc. cient. Argentina, vol. 43, 1897, p. 19. In this memoir Kyle gives analyses of numerous Argentine rivers . The nomenclature , however , is confusing, for descriptive names, such as Negro, Colorado,. Salado, Saladillo, etc., are applied to more than one stream in Argentina, and it is not always easy to identify the river to which a given analysis applies. A B C D E F G co 3 17. 45 11. 59 17. 73 24. 23 21. 59 39. 10 8. 19 so 4 7. 69 17. 97 10. 13 3. 90 6. 15 1. 23 30. 58 Cl 12. 59 18. 11 15. 92 .61 5. 12 4. 43 24. 51 NO, 6. 68 5. 50 1. 95 Ca 6. 18 3. 71 7.37 9. 82 10. 01 17. 82 16. 24 Mg 3. 31 1. 42 2. 78 2. 85 2. 97 1. 96 1. 46 Na 17. 34 24.89 14. 96 3. 75 5. 92 10. 24 15. 78 K 3. 09 4. 06 3. 12 Si0 2 21. 32 10. 82 20. 73 46. 22 44. 32 21. 75 3. 24 ALO, 6. 62 3. 21 'l Fe 2 0 3 4.41 S 4. 81 3. 21 } 3. 92 1. 52 ) J J 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million.. . 91 206 98 40 66 132 651 92 THE DATA OF GEOCHEMISTRY. Analyses of water from rivers in southern part of South America — Continued. H. Rio Primero, Argentina. I. Rio de los Papagayos, Argentina. Analyses H and I by M. Siewert, in R. Napp's The Argentine Republic, 1876, pp. 242, 244. J. Rio Saladillo, Argentina. Analysis by A. Doering. K. Rio de Arias, Salto, Argentina. Analysis by M. Siewert. L. Rio de los Reyes, Jujuy, Argentina. Analysis by M. Siewert. For analyses J, K, and L, see Bol. Acad. nac. cien. Cordoba, vol. 5, 1883, p. 440. M. Rio Frio, district of Taltal, Chile. Analysis by A. Dietze, cited by L. Darapsky in Das Departement Taltal, Berlin, 1900, p. 93. N. Rio Copiapo, Chile. Analysis by P. Lem6tayer, cited by F. J. San Rom&n in Desierto i Cordilleras de Atacama, vol. 3, Santiago, 1902, p. 191. H I J K L M N co 3 39. 47 0. 06 9. 94 39. 13 28. 27 18. 06 6. 46 so 4 5. 76 31. 81 27. 75 13. 24 18. 17 24. 45 36. 50 Cl 6. 41 32. 63 21. 51 2. 77 5. 53 8. 04 no 3 Trace. Ca 16. 53 8. 01 11. 29 19. 63 13. 20 14. 93 6. 61 Mg 3. 27 . 36 2. 87 5. 20 2. 53 2. 63 3. 52 Na 9. 09 26. 48 16. 12 1. 82 7. 19 15. 37 8. 96 K 4. 67 .49 4. 41 5. 75 10. 20 . 36 Si0 2 8. 58 6. 11 11. 57 12. 33 13. 22 35. 39 A1 2 0 3 1. 10 .49 Fe 2 0 3 5. 12 .89 2. 09 3. 30 j 2.20 J S .16 Salinity, parts per million. . . 100. 00 160 100. 00 9, 185 100. 00 1, 213 100. 00 127 100. 00 104 100. 00 186 100. 00 731 These waters show the same order of variation as those of North America. The water of the Amazon, flowing through forests and in a humid climate, is characterized by dominant carbonates and low salinity. In Argentina many of the streams flow through semiarid plains. In their waters sulphates and chlorides predominate and the alkalies are commonly in excess of lime. The Uruguay and some rivers of British Guiana are peculiar because of their high propor- tion of silica — a condition which will be discussed later in the chapter. LAKES AND RIVERS. 93 LAKES AND RIVERS OF EUROPE. Both Bischof and Both cite numerous early and often incomplete analyses of European river waters, but it is not necessary to reproduce them all here. They tell the same story as that told by the eastern rivers of the United States. The predominance of calcium and the carbonic radicle is clearly shown in most cases. For present pur- poses it is well to begin with British waters, and then to pass on eastward. Analyses of British waters. A. Loch Baile a Ghobhainn, Lismore Island, Scotland. Analysis by W. E. Tetlow, Proc. Roy. Soc. Edinburgh, vol. 25, 1905, p. 970. Organic matter not included in this recalculation. A typical calcium carbonate water springing from limestone. B. River Dee near Aberdeen, Scotland. C. River Don near Aberdeen. Analyses B and C by J. Smith, Jour. Chem. Soc., vol. 4, 1850, p. 123. Organic matter rejected. D. The Thames at Thames Ditton. E. The Thames at Kew. F. The Thames at Barnes. Analyses D, E, F, by T. Graham, W. A. Miller, and A. W. Hofmann, Jour. Chem. Soc., vol. 4, 1850, p. 376. Analyses are also given of the Thames at Battersea and Lambeth, of the New River, and several springs. For other analyses of the Thames see J. M. Ashleyj Jour. Chem. Soc., vol. 2, 1848, p. 74, and G. F. Clark, idem, vol. 1, 1848, p. 155. Also R. D. Thomson, idem, vol. 8, 1856, p. 97, and H. M. Witt, Philos. Mag., 4th ser., vol. 12, 1856, p. 114. G. Lough Neagh, Ireland. Analysis by J. F. Hodges, Chem. News, vol. 30, 1870, p. 103. An analysis of the river Bann is also given. See also C. M. Tidy, Jour. Chem. Soc., vol. 37, 1880, p. 268, for partial analyses of the Thames, Lea, Severn, and Shannon. E. Hull, Geol. Mag., 1893, p. 171, cites analyses of Thirlmere, Bala Lake, and the Severn, which I am unable to trace to the original publications. In T. E . Thorpe’s Manual of inorganic chemistry ,- vol. 1, p. 207, analyses of the Clyde and Loch Katrine are given. For analyses of the River Trent, see Jour. Soc. Chem. Ind., vol. 30, 1911, p. 70. A B c D E F G co 3 57. 49 23. 35 23. 15 41. 86 39. 53 33. 90 35. 23 so 4 Trace. 15. 70 16. 29 11. 82 14. 72 18. 10 10. 68 Cl 1. 41 17. 08 14.19 5. 20 4.57 5. 70 9. 62 NO, Trace. . 84 Trace. Trace. . 02 Ca 37. 77 17. 22 16. 32 30. 10 28. 57 27. 00 i7. 71 Mg .25 2. 98 3. 54 1. 95 1. 82 1. 70 1. 31 Na \ .94 113. 60 1 9. 17 2. 26 3. 28 3. 70 15.41 K / / / 2. 25 1. 55 1. 10 SiO, A1 2 0 3 1. 62 6. 41 10.62 3. 26 1 2. 36 5. 00 3.32 Fe 2 0 3 .50 | 3. 66 | 6. 72 > . 46 | 3. 60 | 3. 80 6. 72 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million. . . 160 31 81 272 266 286 155 The high chlorine and sodium in some of these analyses is probably due in part to the proximity of the ocean. In the Thames the regular increase in these radicles as we follow the stream downward is quite evident. The Thames, however, rises in the midland counties of England, where the waters issuing from the oolite are relatively rich in chlorides . 1 See W. W. Fisher, The Analyst, vol. 29, 1904, p. 29. 94 THE DATA OF GEOCHEMISTRY, The next group of analyses 1 relates to the waters of western Europe, namely of Belgium, France, and Spain. Some Swiss waters are included, as tributary to the Rhone. Analyses of waters in western Europe. A. The Meuse at Liege, Belgium. Computed from data given by W. Spring and E. Prost, Ann. Soc. g6ol. Belgique, vol. 11, 1884, p. 123. The Meuse carries past Liege, in solution, nearly 1,082,000 metric tons of solids annually, or 139 tons from each square mile of territory drained. Earlier analyses of the Meuse by J. T. P. Chandelon and J. W. Gunning are cited by Bischof. B. The Seine at Bercy. Analysis by H. Sainte-Claire Deville, Annales chim. phys., 3d ser., vol. 23, 1848, p. 42. C. The Loire near Orleans. Analysis by Deville, loc. cit. D. The Garonne at Toulouse. Analysis by Deville, loc. cit. E. The Doubs at Rivotte. Analysis by Deville, loc. cit. F. The Isere. Analysis by J. Grange, Annales chim. phys., 3d ser., vol. 24, 1848, p. 496. Grange also gives analyses of several small tributaries and correlates them with their geological surroundings. G. The Rhone at Geneva. Analysis by Deville, loc. cit. H. The Rhone. Average of five analyses by L. Lossier, Arch. sci. phys. nat., 2d ser., vol. 62, 1878, p. 220. Organic matter rejected. I. The Arve. Average of six analyses by Lossier, loc. cit. J. Lac Leman. Analysis by R. Brandenbourg, cited by F. A. Forel in Mem. Soc. Helv6t., vol. 29, 1884. Forel cites several other analyses of Lac Leman. See also Risler and Walter, Bull. Soc. vaud., vol. 12, 1878, p. 175. K. Lac d’Annecy. Analysis by L. Duparc, Compt. Rend., vol. 114, 1872, p. 248. L. The Douro. Analysis cited in Mem. Com. mapa geol. Espana, Prov. Salamanca. Analyst not named. A B c D E F co 3 36. 48 39. 78 30. 92 33. 07 50.41 34. 14 S0 4 13. 13 8. 57 1. 72 5. 59 1. 53 24.11 Cl 3. 83 2. 95 2. 16 1. 40 . 74 4.53 no 3 2. 86 4. 44 2. 35 Ca 28. 90 29. 13 14. 31 18. 99 33. 20 25.40 Mg 2. 68 .63 1. 34 . 67 .40 3. 67 Na : 2. 24 2. 87 6. 93 4.42 1. 53 1 4.32 K .87 .86 1. 64 2. 50 .70 / Li . .. . 05 Si0 2 6. 02 9. 59 31. 59 29. 53 6. 91 1. 97 A1 2 0 3 > . 19 5. 29 . 92 1. 86 Fe 2 0 3 ^ 2. 94 .99 4. 10 2. 28 1. 31 Trace. Mn 2 0 3 1. 55 100. 00 100. 00 100.00 100. 00 100. 00 100. 00 Salinity, parts per million. . . . 254 134 137 230 188 G H I J K L C0 3 27.92 36. 69 42. 37 33. 87 59. 14 33. 73 so 4 23. 18 26. 68 18. 81 26. 66 Trace. 23. 37 Cl .55 . 71 1. 46 .52 .69 7. 74 no 3 3. 13 . 31 . 32 PCL .41 Ca 24. 89 26. 42 29.64 27. 81 34. 40 23.93 Mg 1. 48 3. 66 3. 17 2. 23 3. 06 6. 05 Na 2. 75 \ 3.98 \ 2.53 2. 53 Trace. 2.00 K . 88 / / .25 Trace. 1. 64 Si0 2 13. 08 1. 55 1. 70 5.63 2. 71 1. 03 ALOo 2. 14 I * 50 iTraces. . 10 ilA 2 v 3 ----- Fe 2 0 3 F 100. 00 100. 00 100. 00 100. 00 100.00 100. 00 Salinity, parts per million. . . . 182 170 192 152 144 195 » J. Thoulet (Bull. Soc. gdog., 7th ser., vol. 15, 1894, p. 557) gives partial analyses of lakes in the Vosges. For French lakes in general, see A. Delebecque, Les lacs frangais, Paris, 1898. See also A. Delebecque and L. Duparc, Compt. Rend., vol. 114, 1892, p. 984; and Arch. sci. phys. nat., 3d ser., vol. 27, 1892, p. 569; VOl. 28, 1892, p. 502. LAKES AND RIVERS. 95 In the mountain complex of the Alps, including the Bavarian and Austrian highlands, several great rivers of western and central Europe take their rise. At their headwaters are many small lakes, and these have been exhaustively studied. In an elaborate thesis by F. E. Bourcart, 1 analyses are given of 33 Alpine lakes, and each one is dis- cussed in the light of its geologic relations. The following table gives a selection from this mass of material. Analyses of water from Alpine lakes. A. Lac Taney, Canton Valais. In the Cretaceous. A typical calcareous water. Drains into the Rhone. B. Lac de Champex, Canton Valais. In microgranulite and protogine. A type of the water derived from igneous rocks. Drains into the Rhone. C. Lac Noir, Canton Fribourg. In the Flysch, but also fed by waters from the Trias. Drains through the Aar into the Rhine. D. Lac d’Amsoldingen, Canton Berne. In the Flysch and Molasse. Drains into the Aar. E. Lac Ritom, above Airolo, Canton Ticino. Surface water. F. Lac Ritom, lower layer of water, below 13 meters depth. This lake drains southward into Italy. A B c D E F co 3 53. 21 29. 96 26. 94 53. 84 20. 00 2. 29 so 4 5. 29 11.93 38. 35 3. 32 47. 27 69. 89 Cl .87 9. 96 .57 1. 77 Ca 33. 74 19. 15 29. 65 33. 30 22. 12 22. 15 Mg 1. 99 1. 32 2. 27 1. 76 5. 47 4. 96 Na .75 8. 32 .64 1. 80 1. 22 .09 K .74 4. 00 .38 .93 1. 64 .15 Si0 2 2. 37 13. 93 .71 3. 03 2. 28 .42 Al 2 0 3 -f-Fe 2 03 a v 1.04 1.43 .49 .25 Trace. .05 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 122 27 | 270.5 201.7 122.5 2, 373 o Including traces of manganese. Analyses A to D well illustrate the differences in origin of the waters. E and F represent a lake of extraordinary character. It contains two distinct layers of water of quite dissimilar nature. The upper layer is merely the water of its affluents, which flows over the denser water below. The latter is essentially a strong solution of calcium sulphate, derived from neighboring beds of gypsum. The two layers do not commingle, and the lower one has a distinctly higher temperature than the upper, except at the surface. At 11 meters depth the temperature is 5.1°; at the bottom it is 6.6°. A similar phenomenon, but even more strongly marked, is shown by the Illyes Lake in Hungary, which will be described later. The following table contains recalculated analyses of water from several lakes in the Bavarian and Austrian highlands. 2 They belong to the basin of the Danube, into which they drain through the valleys 1 Thesis, Univ. Geneva, 1906. Les lacs alpines suisses, 4°, 130 pp. A few selected analyses appear in Arch. sci. phys. nat., 4th ser., vol. 15, 1903, p. 467. 2 See also incomplete analyses of the Stamberger, Kochel, and Walchen lakes by J. Gebbing, Jahresb. Geol. Gesell. Miinchen, 1901-2, p. 55. Also W. Ule’s monograph on the Wiirmsee, published by the Verein fur Erdkunde, Leipzig, in 1901. 96 THE DATA OF GEOCHEMISTRY. of the Isar, Inn, and Traun. One Italian lake is included in this table on account of its Alpine relationship. Analyses of water from Bavarian and AiLStrian lakes. A. Walchensee. B. Kochelsee. C. Stamberger- or Wiirmsee. D. Tegemsee. Mean of two analyses. E. Schliersee. Mean of two analyses. F. Chiemsee. Mean of five analyses. G. Konigsee. Mean of two analyses. Analyses A to G by A. Schwager, Geognost. Jahresbefte, 1894, p. 91; 1897, p. 65. All these lakes are in the Bavarian highlands. H. Hallstattersee, Upper Austria. Mean of two analyses, summer and winter samples, by N. von Lorenz, Mitt. Geog. Ges. Wien, vol. 41, 1898, p. 1. I. Traun- or Gmundenersee, Upper Austria. Analysis by R. Godeflroy, Jahresb. Chemie, 1882, p. 1623. Organic matter rejected. J. Lago di Garda, northern Italy. Analysis by Schwager, Geognost. Jahreshefte, 1894, p. 91. Analyses of Italian waters seem to be rare. For partial analyses of three small streams near Oderzo, in northwest- ern Italy, see M. Spica and G. Halagian, Gazz. chim. itaL, voL 17, 1887, p. 317. A B c D E co 3 50.83 48. 46 54. 69 48. 25 50. 74 so 4 11 . 62 14. 78 4. 73 15. 24 11. 15 Cl .58 .48 1. 57 .58 . 55 NO, .07 Ca 26.49 24. 66 24. 09 26. 17 26. 94 Mg 7.00 6. 17 7. 98 6 . 56 5. 78 Na .99 1. 52 .96 1. 10 1. 05 K . 58 1. 52 2. 14 .88 1. 07 Si0 2 1.00 1 . 60 1. 26 .44 1 . 62 AI 2 O 3 } .91 .73 2.44 .73 1. 05 Fe 2 0 3 .04 .07 . 05 . 05 Ti0 2 .04 100 . 00 100.00 100.00 100.00 100.00 Salinity, parts per million * 121 227 139 207 190 F G H I J 49. 58 50. 59 38. 43 51.68 53. 29 soj 12. 09 6.54 9.43 8 . 99 4.17 Cl.. 1. 92 .65 10. 94 2.44 3. 13 PCL . 05 Ca 23. 22 32. 65 26. 37 27.54 24 56 Mg 8. 17 3. 41 3. 88 5. 21 6 . 66 Na 2. 18 .70 6.50 2 . 82 2. 49 K .97 1. 24 2. 77 2. 01 Si0 2 .92 1. 73 1. 31 .31 2. 33 A1 2 0 3 .89 2. 33 1 .37 \ 1.01 1 . 21 Fe 2 0 3 .06 .11 / / . 15 100.00 100.00 100.00 100.00 100.00 Salinity, parts per million 191 98 137.5 99 178 These lakes are surrounded by sedimentary rocks, and all except that of Hallstatt are much alike chemically. Magnesium, with two exceptions, is decidedly above its average amount in lake and river waters, a fact which is due to the presence of much dolomite in the lake region. The high chlorine and sodium of the Hallstatt lake are derived from neighboring salt beds. LAKES AND RIVERS. 97 For the Rhine and its tributaries a good number of analyses are available.® The table following contains a part of them, recalculated to modern standards, with organic matter rejected. Analyses of water from the Rhine and its tributaries. A. Lake of Zurich. Analyses by Moldenhauer, 1857, cited by Roth, Allgemeine und chemische Geologie, vol. 1, p. 456. B. The Aar at Bern. Analysis by J. S. F. Pagenstecher, 1837, cited by Roth. C. The Rhine at Basel. Analysis by Pagenstecher, loc. cit. D. The Rhine at Strasburg. Analysis by H. Sainte-Claire Deville, Annales chim. phys., 3d ser., vol. 23, 1848, p. 42. E. The Rhine near Mainz. Analysis by E. Egger, Notizbl. Ver. Erdkunde, Darmstadt, 1887, p. 9. An earlier analysis is in the volume for 1886, p. 21. F. The Rhine at Cologne. Mean of seven analyses by H. Vohl, Jahresb. Chemie, 1871, p. 1§23. G. The Rhine at Arnheim. Analysis by J. W. Gunning, Jahresb. Chemie, 1854, p. 767. H. The White Main. I. The Red Main. J. The united Main. Analyses H, I, and J by E. Spaeth, Inaug. Diss. Erlangen, 1889. Spaeth also gives analyses of water from the Rodach, Haslach, and Kronach, tributaries of the Main. K. The Main above Offenbach. Analysis by C. Merz, Jahresb. Chemie, 1866, p. 9S7. L. The Main at Frankfort. Analysis by G. Kerner. Cited by F. C. Noll, Inaug. Diss. Tubingen, 1866, from a report published at Frankfort in 1861. M. The Main near its mouth. Analysis by E. Egger, Notizbl. Ver. Erdkunde, Darmstadt, 1886, p. 17. N. The Nahe at Bingen. Analysis by Egger, idem, 1887, p. 5. A B c D E F G co 3 51. 64 48. 60 53. 05 36. 69 41. 12 46. 96 35. 79 S64 7. 90 14. 63 7. 96 8. 38 11. 13 12. 95 12. 23 Cl .59 .08 .57 .52 3. 65 4. 22 7. 10 NO, 1. 00 1. 63 po, ( 6 ) 31. 81 .24 Ca 29. 10 30. 54 33. 53 25. 30 26. 48 26. 18 Mg 5. 11 4. 71 2. 87 .61 3. 95 6. 15 3. 84 Na -- 1. 60 } - 18 | .73 2. 17 2. 08 2. 73 6. 34 K 2. 00 .66 1. 05 .02 4. 04 Si0 2 2. 06 1.26 1. 29 21. 07 2. 69 } .89 . 15 3. 59 | .89 A1 2 0 3 1. 09 .04 2. 51 .06 — ~ a - - * Salinity, million . parts per 100. 00 141 100. 00 213 100. 00 166 100. 00 232 100. 00 178 100. 00 190 100. 00 159 H I J K L M N C0 3 36. 15 41. 83 39. 69 34. 39 35. 85 29. 43 35. 43 S0 4 16. 33 14. 89 15. 46 26. 41 24. 69 22. 43 7. 91 Cl 5. 60 5. 00 4. 76 4. 69 1. 91 8. 39 15. 37 NO, 1. 66 .71 1. 43 1. 12 2. 61 (a) 19. 57 . 41 Ca 22. 58 23. 91 23.07 23. 56 21. 81 18. 64 Mg 4. 26 5. 85 5. 52 6. 90 7. 30 5. 77 5. 54 Na 4. 10 2. 64 2. 86 1. 73 1. 25 6. 64 4. 28 K 1. 66 1. 75 2. 04 Trace. 1. 44 5. 40 Si0 2 6. 47 } 1.19 J 3. 10 } .32 J 4. 69 } .48 1. 90 } .42 6. 67 i ro 4. 12 4. 05 A1 2 0 3 . 99 FO..O ?• . 52 .10 \ . 36 0 J J ) Salinity, million _ parts per 100. 00 126 100. 00 194 100. 00 147 100. 00 240 100. 00 221 100. 00 299 100. 00 182 a For an imperfect analysis of the Bodensee (Lake of Constance) see II. Bauer and H. Vogel, Jahres- hefte Ver. vaterl. Naturk. Wurttemberg, vol. 48, 1892, p. 13. Many partial analyses of waters from Rhine tributaries are given by E. Egger, Notizbl. Ver. Erdkunde, Darmstadt, 1908, p. 105; 1909, p. 87. These two papers are on the hydrochemistry of the Rhine. b Included with AI 2 O 3 , etc. 97270°— Bull. 616—16 7 98 THE DATA OF GEOCHEMISTRY, These analyses are evidently of very unequal value. The high silica found in the Khine by Deville is suspicious, and yet Deville was an accurate manipulator. One of the most thorough hydro chemical studies ever made of any European river system is that of the Elbe and its Bohemian tribu- taries by J. Hanamann . 1 In two memoirs upon the waters of Bo- hemia he gives over one hundred and twenty analyses, tracing nearly all of the important streams in the upper Elbe basin to their sources, correlating each one with the geological formations in which it rises, and showing the effect produced by their union. Of the Elbe itself thirteen analyses are given; of the Eger, eight; of the Iser, six, and so on. From this wealth of material only a small part can be reproduced here, recalculated as usual to our uniform standard and beginning with the tributaries. A few analyses are also given from a rich mass of data derived from other authorities . 2 Analyses of the Elbe and its tributaries. A. The Moldau above Prague. Mean of three analyses by A. BSlohoubek, Sitzungsb. K. bohm. Gesell. Wiss., 1876, p. 27. B. The Moldau below Kralup. C. The Adler near its mouth. D. The Iser at its source. E. The Iser near its mouth. F. The Eger at its source. Analysis by E. Spaeth, Inaug. Diss., Erlangen, 1889. G. The Eger above Konigsberg. H. The Eger near its mouth, at Bauschowitz. A B c D E F G H co 3 32. 86 34. 52 46. 23 21. 29 47.74 11. 68 26. 64 26.84 so 4 11. 95 10. 20 7.44 6. 94 6. 55 7. 06 19. 22 27. 45 Cl 10. 69 10. 17 3.20 11. 08 3. 00 23. 85 8. 16 6. 55 NO, 1. 76 1. 43 1. 24 . 78 . 50 .46 . 47 .36 Ca 13. 52 16. 71 26. 73 8. 14 28. 15 6. 79 12. 86 15. 42 Mg 4. 88 4. 64 2. 45 2. 19 2. 47 2. 24 3. 51 4. 05 Na 10. 22 8. 40 4. 29 13. 86 3. 71 11. 93 11. 66 10. 46 K 5. 19 4. 05 2. 38 5. 54 2. 01 6. 71 2. 98 3. 50 Si0 2 8. 96 4. 99 5. 53 28. 39 4. 96 26. 07 12. 19 4. 17 (Al,Fe)A 1. 26 4. 20 .32 1. 33 .63 3. 67 2. 28 1. 10 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 74 104 195 16 183 17 80 176 1 Archiv Natur. Landesdurchforschung Bohmen, vol. 9, No. 4, 1894; vol. 10, No. 5, 1898. 2 Other data relative to the Elbe and its tributaries are given by J. J. Breitenlohner (Verhandl. K.-k. geol. Reichsanstalt, 1876, p. 172) and F. Ullik (Abhandl. K. bohm. Gesell. Wiss., 6th ser., vol. 10, 1880). For analyses of the Elbe at Lauenburg, Hamburg, and Neufeldt, see H. Siissenguth, cited by F. Schucht, Jahrb. K. preuss. geol. Landesanstalt, vol. 25, 1897, p. 442. An analysis of the Moldau at Prague by F. Stolba is given in Jour. Chem. Soc., vol. 27, 1874, p. 971. For an analysis of River Radbuza above Pilsen, see the same author, Jahresb. Chemie, 1880, p. 1521. According to A. Schwager (Geognost. Jahreshefte, 1891, p. 35), the Saale carries out of Bavaria, annually, 17,380,000 kilograms of dissolved matter, and the Eger carries 14,000,000 kilograms. For additional data on the waters of the Elbe and the Saale, see R. Kolkwitz and F. Ehrlich, Mitt. K. Priifungsanstalt fur Wasserversorgung, Heft 9, Berlin, 1907, p. 1. LAKES AND RIVERS. 99 Analyses of the Elbe and its tributaries — Continued. I. The Saale near its source. Analysis hy Spaeth, loc. cit. J. The Saale at Blankenstein. Analysis by A. Schwager, Geognost. Jahreshefte, 1891, p. 91. Sch wager also gives analyses of the Saale at three other points, of its tributaries the Pulsnitz, Schwesnitz, Regnitz, and Selbitz, of the Eger, and of the upper Main. K. The Weisswasser, one of the two chief sources of the Elbe. L. The Elbe at Celakowitz, above the mouth of the Iser. M. The Elbe at Melnik, above the mouth of the Moldau. N. The Elbe at Leitmeritz, above the Eger. O. The Elbe at Lobositz, below the Eger. ’ P. The Elbe at Tetschen, near the Bohemian frontier. The analyses are by Hanamann, except where otherwise stated. I J K L M N 0 P co 3 14. 71 27. 01 16. 84 45. 87 45.04 40. 27 38. 41 35. 88 S04 5. 84 20. 94 12. 86 8. 95 8. 88 10. 86 12. 45 14. 88 Cl no 2 19. 40 10. 34 .43 7. 61 3. 27 3. 56 5. 00 5. 96 5. 87 N0 3 1. 62 4. 28 . 90 .94 1. 22 1. 28 1. 40 Ca 4. 02 14.- 19 8. 76 26. 41 26. 37 22. 87 22. 19 20. 92 Mg 6. 37 5. 98 2. 19 3. 21 2. 77 3. 24 3. 23 3. 63 Na 9. 90 8. 98 11. 06 3. 93 4. 02 5. 62 6. 35 6. 09 K 4. 66 2. 99 2. 01 2. 46 3. 06 2. 79 2. 87 3. 16 Si0 2 35. 10 4. 79 31. 21 4. 09 4. 66 7. 27 6. 42 7. 13 A1 2 0 3 F6 2 0 3 j>Traces 1. 88 .85 } 3. 18 } .91 | .70 CO 00 } .84 } 1.04 Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 17 117 13 221 205 157 153 148 At their sources these streams are characterized by very low salinity and a high proportion of silica and alkalies. They grad- ually increase in salinity, and by blending one with another approach more and more nearly the normal type of river waters. The Eger is unusually rich in alkalies and chlorine. The minor tributaries of the Elbe vary widely in composition, but in general calcium and car- bonates are the chief constituents. In the Schladabach, however, a small affluent of the Eger, sodium and the sulphuric radicle pre- dominate, and in the Chodaubach, another tributary of the same river, there is a solution of gypsum with no carbonates. When the Schladabach enters the Franzensbad moor it carries 94 parts per million of fixed mineral matter; it leaves the moor with a load of 1,542 parts. This change serves to show the importance of ground water in modifying the chemical character of a stream — a point already noticed in studying the rivers of Colorado. For details con- cerning these and many other small tributaries of the Elbe basin, Hanamann’s original memoirs should be consulted. They will well repay careful study. 100 THE DATA OF GEOCHEMISTRY. One table of analyses given by Hanamann is peculiarly instructive. It consists of averages, showing the composition of Bohemian waters as related to the rocks from which they flow. These averages, reduced to the standard herein adopted, are as follows: Average composition of Bohemian waters, classified according to source. A. From phyllite, five analyses. B. From granite, six analyses. C. From mica schist, six analyses. D. From basalt, four analyses. * E. From the Cretaceous, four analyses. A B c D E co 3 35. 94 30. 49 32.14 46. 85 33. 01 so 4 6. 45 14. 12 12. 86 7. 94 27. 69 Cl 10. 15 6. 39 7. 24 1. 66 2. 87 Ca 11. 91 11. 89 12. 61 20. 07 22. 12 Mg 5. 02 3. 58 5. 08 5. 76 5. 29 Na 11. 20 10. 57 10. 85 6. 22 3. 43 K 4. 39 5. 63 4. 22 3. 20 2. 72 Si0 2 14. 94 17. 33 15. 00 7. 67 2. 87 Fe 2 0 3 .63 Salinity, parts per million 100. 00 48 100. 00 65 100. 00 74 100.00 343 100.00 603 The high figures for silica and sodium in the first three of these analyses reflects the origin of the waters in areas of crystalline rocks. The water of the Danube and its tributaries above' Vienna has been the subject of many investigations. The following table contains a selection from among them. Except when otherwise stated the analyses are by A. Schwager . 1 1 Geognost. Jahreshefte, 1893, p. 84. In Schwager’s analyses the iron is given as FeO. It is here recal- culated into Fe 2 0 3 . Traces of Mn, Ti0 2 , and P 2 0 5 are ignored. LAKES AND RIVERS. 101 Analyses of water from the Danube and its tributaries. A. The Woemitz above Wassertriidingen, Bavaria. B. The Altmuhl above Herrieden, Bavaria. Analyses A, B, by E. Muller, Inaug. Diss., Erlangen, 1893. Other dissertations upon Bavarian waters are by E. Kohn, 1889; M. Lechler, 1892; J. Mayrhofer, 1885; all from Erlangen. Spaeth’s dissertation has already been cited. There is also one from W iirzburg, by F. Pecher, 1887. In each dissertation the waters are studied geologically. C. TheNaab. D. The Regen. For older but incomplete analyses of the Regen, Ilz, and Rachelsee, see H. S. Johnson, Liebig’s Annalen, vol. 95, 1855, p. 230. An analysis of Danube water taken at Vienna was made by G. Bischof in 1852. An analysis of the Naab at its source is given by Spaeth, loc. cit. E. The Isar. For an analysis of the Isar at Munich, see G. Wittstein, Jahresb. Chemie, 1861, p. 1097. F. The Vils at Vilshofen. Analysis by C. Metzger, Inaug. Diss., Erlangen, 1892. Metzger also gives analyses of the Regen, Naab, Ilz, and Inn, of the two Arber Lakes and Black Lake at the headwaters of the Regen, of the Luhe, Pfreimt, and lesser Vils, tributaries of the Naab, and of the Danube at five differ- ent points. His work curiously overlaps or coincides with that published by Schwager. It includes geologic correlations. G. The Ilz. H. The Inn. I. The Erlau. J. The Danube above the Naab. K. The Danube above Regensburg. L. The Danube above the Ilz and Inn. M. The Danube 12 kilometers below Passau. N. The Danube at Greifenstein, 20 kilometers above Vienna. Mean of 23 analyses by J. F. Wolfbauer, of samples taken at intervals of 16 days throughout the year 1878. Monatsh. Chemie, vol. 4, 1883, p. 417. O. The Danube at Budapest. Analysis by M. Ballo, Ber. Deutsch. chem. Gesell., vol. 11, 1878, p. 441. Bicarbonates are here reduced to normal salts. A B C D E F G H CO, 41. 14 12. 64 47. 23 27. 55 49. 53 52. 43 15. 87 44. 85 so 4 19. 36 50.31 9.54 11. 14 12.07 3. 29 18. 26 14. 40 Cl 3. 66 1. 93 4. 42 5. 88 .46 2. 01 2. 78 2. 20 NO, .11 .37 .59 .09 NO, .23 . 71 .59 . 28 Ca 21. 81 23. 63 20. 70 12. 07 25. 65 21. 81 4. 37 25. 10 Us 7. 54 1. 15 8. 14 4. 02 6.04 7. 85 2. 18 6. 23 Na 2. 37 1. 26 3. 11 6. 50 2. 14 3. 67 9. 92 2. 20 K 2. 29 7. 40 1. 81 4. 37 1.41 4. 79 4. 37 1. 13 Si0 2 1. 28 } .55 .98 3. 51 19. 50 1. 45 3. 72 1 32. 54 2. 89 ALO, . 90 6. 50 1. 04 7. 94 .44 Fe,0, ^ . 70 .30 1. 39 .21 } * 43 .59 .19 J J Salinity, parts per million 100. 00 325 100. 00 461.5 100. 00 110 100. 00 38.3 100. 00 203.5 100. 00 217 100. 00 30 100. 00 166 I J K L M N O co 3 16. 77 53. 51 51. 70 50. 16 48. 29 50. 10 49.03 S0 4 14. 78 7. 11 8. 54 8. 85 10. 52 8. 81 13. 69 Cl N0 2 5. 75 .41 1. 20 1. 31 .06 1. 20 .06 2. 25 .06 1. 44 1.40 NO, .41 .23 .25 2. 14 1. 19 1. 24 Ca 8. 62 26. 88 27. 40 26. 59 25. 46 26. 28 26. 78 Mg 1. 50 6. 21 6. 00 6. 01 6. 31 5. 95 6. 97 Na 8. 95 1.47 1. 12 1. 34 1. 84 1. 69 .93 K 4. 37 .96 . 72 1. 12 1. 36 .94 Si0 2 28. 73 9. 30 1.59 .78 2. 42 .42 2. 01 .46 2. 20 .46 3. 35 1. 20 Fe 2 0 3 .41 .06 .06 .06 .06 .20 Trace. Salinity, parts per 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 million 47 217 204 201 184 167 151 102 THE DATA OF GEOCHEMISTRY. Although the tributary waters (which should include the waters of the Bavarian lakes as given in a previous table) show great differ- ences in character, the regularity exhibited by the Danube itself is very striking. The water of the Danube is essentially a calcium carbonate water, but the sulphates in it tend to increase in going downstream. According to Wolfbauer, the river carries past Vienna a daily charge of 25,000 metric tons of matter in solution. This is equivalent to an annual load of 9,125,000 metric tons. The mechani- cal sediment transported at the same time is only three-fifths as much. Analyses of a few more waters of central Europe are given in tne next table . 1 Analyses of water from central Europe. A. The Weser at Return, 41 kilometers above its mouth. Mean of two analyses by F. Seyfert, Inaug. Diss., Rostock, 1893. Contamination, tidal or other, is evident. B. The Oder near Breslau. Sample taken at high water. Analysis by O. Luedecke, Das Wasser des Oderthales, etc., Leipzig, 1907. Another sample at low water showed contamination. Other analyses of ground and well waters are given. C. The Vistula at Culm. Analysis by G. Bischof, Lehrbuch der chemischen und physikalischen Geo- logie, 2d ed., vol. 1, 1863, p. 275. D . Balaton- oi Plattensee, Hungary . Analysis by L. von Ilosvay , in Resultate der wissensch. Erforsch. Balatonsees, vol. 1, 1898, p. 6. Reduced from bicarbonate form. A B C D CO, 22. 13 17. 92 47. 78 38. 80 so 4 22. 77 23. 60 9. 49 21. 47 ci : 17. 54 5. 46 2. 70 2. 98 Ca 18. 50 28. 09 28. 52 8. 87 Mg 3. 11 3. 28 4. 44 12. 81 Na 10. 25 6. 45 1. 57 6. 14 K 1. 95 5. 35 .39 3. 27 Si0 2 3. 75 6. 57 4. 49 4. 48 ALO, .82 Fe 2 0 3 | 3.28 } . 62 ) .36 Salinity, parts per million 100. 00 281 100. 00 91.5 100. 00 178 100. 00 512 The Balaton Lake has an exceptional composition. The other analyses in the table are of minor importance. The rivers repre- sented by them need more study. 1 For three small lakes near Halle and Eisleben see W. Ule, Die Mansfelder Seen, Inaug. Diss., Halle, 1888. A memoir by J. Wolff (Chemische Analyse der wichtigsten Fliisse und Seen Mecklenburgs, Wies- baden, 1872) contains analyses of several small rivers and lakes. See also A. Jentzsch ( Abhandl. K. preuss. geol. Landesanstalt, new ser., Heft 51, p. 98, 1912) for other analyses of North German lakes. LAKES AND RIVERS. 103 For Sweden a single table of analyses must suffice, reduced from the data given by O. Hofman-Bang. 1 The month in which the water was taken is given for each analysis. Analyses of Swedish waters. A. The Byske-elf, July. B. The Klarelf, April. C. The Klarelf, October. D. The Ljusnan, June. E. The Indalself, June. F. The Fyris, April. G. The Fyris, October. A B c D E F G co 3 50. 60 39. 44 38. 68 43. 11 43. 93 29. 14 14. 30 so 4 4. 01 5. 85 7. 63 4. 57 7. 24 24. 58 39. 08 Cl 4. 75 5. 10 2. 24 4. 53 3. 81 3.15 3. 27 NO, .46 Trace. Trace. .13 P0 4 Trace. Ca 11.57 14. 95 11. 67 17. 34 18. 04 27. 49 27. 99 Mg .64 .51 .51 .24 .38 1. 69 2.11 Na 9. 90 I 18. 77 8. 42 9. 05 11. 33 2. 92 3. 33 K 9. 00 / 3. 78 5. 87 4. 89 2. 36 1. 73 Si0 2 7. 57 13. 09 19. 17 13. 70 5. 78 6. 00 6. 19 (Al,Fe) 2 0 3 1. 96 2. 29 7. 44 1. 59 4. 60 2. 67 1. 87 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 19. 25 27.6 25.5 24.8 33.7 170.3 178.1 The remarkably low magnesia and high proportion of alkalies are distinctive peculiarities of these waters. The variability of the Fyris affords another good example of the fact that little significance can be attached to a single analysis of a river water. i Bull. Geol. Inst. Upsala, vol. 6, 1905, p. 101. In addition to his own work the author cites other analyses of Swedish river and spring waters. Solvent denudation in Norrland he estimates at 9 metric tons per square kilometer, or 23.3 tons per square mile. 104 THE DATA OF GEOCHEMISTRY. Of Russian fresh waters only a few analyses- are available, as follows : Analyses of Russian waters. A. The Angemsee. Mean of two analyses. B. The Babitsee. Analyses A and B by F. Ludwig, Die Kiistenseen des Rigaer Meerbusens, published by the Naturforscher- Verein at Riga, 1908. This memoir contains analyses of 27 small lakes near Riga and close to the Gulf of Riga. Most of them are of calcium carbonate waters, but in a few the sulphate is predominant. Analyses C to G are all by C. Schmidt of Dorpat. C. Lake Onega. Mel. chim. phys. Acad. St. Petersburg, vol. 11, 1882, p. 637. D. Lake Peipus. Bull. Acad. St. Petersburg, vol. 24, 1878, p. 423. Schmidt has also analyzed water from the smallrivers Embach and Velikaya, tributary to Lake Peipus. See Mel. chim. phys., vol. 8, 1873. p. 494. E. The Dwina at Archangel. Analysis cited by J. Roth, Allgemeine chemische Geologie, vol. 1, p. 457. F. River Om above Omsk. Mem. Acad. St. Petersburg, vol. 20, No. 4, 1873. G. Lake Baikal, Siberia. Same reference as analysis B. H. The Dniester near Odessa. Analysis by J. G. N. Dragendorff, Jahresb. Chemie, 1863, p. 885. Partial analyses of five Finnish river and lake waters are given by O. Aschan, Jour, prakt. Chemie, 2dser., vol. 77, 1908, p. 172. For an analysis of the small Lake Ingol, Government of Yeneseisk, Siberia, see S. S. Zaleski, Chem. Zeitung, vol. 16, 1892, p. 594. A B c D E F G H co 3 51. 80 40. 14 25. 76 59. 57 26. 38 43. 73 49. 85 32. 51 so 4 7. 51 23. 45 5. 36 .62 18. 95 2. 15 6. 93 23. 62 Cl 2. 99 1. 09 13. 97 3. 69 17. 71 12. 81 2.44 8. 93 NO, 4. 11 .45 .21 P0 4 .47 . 14 .29 .72 Ca 23. 57 27. 10 8.99 25. 54 12. 38 11. 24 23. 42 25. 25 Mg 7. 89 5. 49 6.86 4. 15 7.58 9. 68 3. 57 5.33 Na 2. 18 .88 13. 34 2. 75 8. 98 9.64 5. 85 .61 K 1.00 .33 9.52 2. 07 5.55 2. 82 3.44 3. 75 Rb . 11 Trace. NH 4 . . .56 . 10 .08 ■ * * Si0 2 1. 61 .84 10. 52 . 78 1. 74 6. 51 2.03 AloO, . 57 . 55 •* j - a 2 v ^3 Fe,0, .88 . 13 .43 .14 .44 1.42 1. 46 100. 00 100. 00 100. 00 100.00 100. 00 100. 00 100.00 100.00 Salinity, parts per million 131 238 49.4 106 187 447 69 197 LAKES AND RIVERS. 105 RIVERS OF INDIA AND JAVA. Analyses of Asiatic fresh waters, apart from the two Siberian examples cited in the preceding table, seem to be very rare. A few only are available for citation. Analyses of waters from India and Java. A. The Mahanuddy near Cuttack, India. Analysis by E. Nicholson, Jour. Chem. Soc., vol. 26, 1873, p. 229. Fe recalculated into Fe 203 . Part of the silica is probably combined as a silicate, being needed to saturate the bases. B. The Serajoe at Djenggawoer, Java. Analysis by E. C. J. Mohr, Mededeelingen Dep. Landbouw, No. 5, Batavia, 1908, p. 81. Another analysis is given of the river at another point. C. The Merawoe. Analysis by Mohr. D. The Pekatjangan. Analysis by Mohr. The last two rivers are tributaries of the Serajoe. Mohr did not determine carbonic acid. It is here calculated, in all three analyses, to satisfy bases. The salinity here therefore differs from that given by Mohr. A B c D co 3 27. 06 26. 01 29. 38 30. 84 so 4 1. 08 14. 78 16. 84 18. 26 Cl 2.04 5. 74 5. 61 3.04 NO, 7.44 P0 4 .72 1. 64 1. 31 1. 21 Ca 15. 78 11. 75 14. 69 16. 64 Mg 4. 62 3. 45 3. 37 2. 43 Na 5. 92 9. 12 4. 95 6. 59 K 1. 64 3. 37 3. 83 3. 34 Si0 2 33. 45 23. 81 19. 65 1 c>i-r 17. 25 } .40 A1 2 0 3 Fe 9 0o .25 } .33 S .37 J J J Salinity, parts per million 100. 00 86 100. 00 122 100. 00 107 100. 00 99 The Mahanuddy rises in a region of igneous and crystalline rocks and its silica is therefore relatively high. The same appears to be true of the Javanese rivers. 106 THE DATA OF GEOCHEMISTRY. THE NILE . 1 The water of the Nile 2 has been repeatedly analyzed, with varying results. The best data are as follows: Analyses of water from the Nile. A. The Victoria Nyanza. Analysis by O. Chadwick and B. Blount, Minutes of Proc. Inst. Civil Eng., vol. 56, p. 39, 1904. B. The White Nile near Khartoum. Average of three analyses. C. The Blue Nile. Average of three analyses. Analyses B and C by W. Beam, Second Kept. Well- come Research Lab., Khartoum, 1906. D. Average of 12 analyses of monthly samples, taken from the lower Nile between June 8, 1874, and May 13, 1875. Analyses by H. Letheby, cited by S. Baker in Proc. Inst. Civil Eng., vol. 60, 1880, p. 376. The total solids contained 10.36 per cent of organic matter. E. The Nile, about two hours’ journey below Cairo. Analysis by O. Popp, Liebig’s Annalen, vol. 155, 1870, p. 344. The total solids contained 12.02 per cent of organic matter. A B c D E CO, 42. 10 42. 97 41. 74 36. 50 36. 02 so 4 1. 92 . 25 5. 62 17. 44 3. 93 Cl 9. 28 4. 58 2. 19 4. 47 2. 83 NO, .25 . 11 Trace. P0 4 Trace. . 59 Ca 6. 96 9. 78 18. 38 20. 10 13. 31 Mg 5. 08 3. 00 4. 66 4. 01 7. 39 Na 25. 13 17. 66 5. 43 3. 04 13. 14 K 6. 79 1. 32 7. 97 3. 26 Si0 2 7. 61 14. 72 20. 55 16. 88 Fe 2 0 3 1. 92 } 6. 47 2. 65 J Salinity, parts per million 100. 00 135 100. 00 174 100. 00 130 100. 00 168 100. 00 119 In Letheby’s analyses the excess of potassium over sodium is very peculiar, and highly improbable. Numerous partial analyses of Nile water cited by Lucas discredit the determinations, and also show that the composition of the water is very variable. In the White Nile the proportion of sulphates is insignificant. Beam accounts for the latter fact by supposing the sulphates to be reduced to carbonates by the organic matter of the “sudd.” South of the “sudd” the White Nile contains appreciable sulphates; after leaving the “sudd” it is nearly free from them. 1 An important memoir by A. Lucas (The chemistry of the River Nile: Survey Dept. Paper No. 12, Ministry of Finance, Egypt, 1908) contains much chemical matter in addition to the analyses cited here. A Chelu (Le Nil, le Soudan, l’Egypte, Paris, 1891) gives some very questionable analyses of the Blue Nile, the White N ile, and the N ile near Cairo. According to Ch41u the river carries past Cairo annually 51,428,500 metric tons of suspended solids and 20,772,400 metric tons in solution. On nitrates in the Nile see A. Muntz, Compt. Rend., vol. 107, 1888, p. 231. 2 Analyses of the other great African rivers seem to be lacking. For the ChGif and references to some smaller Algerian streams see p. 67 of this bulletin. LAKES AND RIVERS. 107 ORGANIC MATTER IN WATERS. Up to this point we have considered only the fixed inorganic matter found in natural waters; but other impurities which have geological significance are also present. All such waters contain dissolved gases, especially oxygen, nitrogen, and carbon dioxide, and sometimes hydrogen sulphide. The rain brings also nitric acid and ammonia to the soil, and so into the ground water; and organic substances are invariably found in it in greater or smaller quantities. These gases and compounds interact in a great variety of ways, and directly or indirectly play an important part in the decomposition of rocks. We have already noted the importance of carbonic acid as a weathering agent, we have seen in a previous chapter how dis- solved air represents a concentration of oxygen, but so far the organic matter of water has been tacitly ignored. Its quantity, in percentages of total solids, can be computed in some cases from published analyses. A few of the available figures are as follows: Percentage of organic matter in the dissolved solids of river waters . Danube James Maumee Nile Hudson. . . . Rhine Cumberland Thames. . . . Genesee 3. 25 4. 14 4. 55 10. 36 11. 42 11. 93 12. 08 12. 10 12. 80 Amazon Mohawk Delaware Lough Neagh Xingu Tapajos Plata Negro Uruguay 15. 03 15.34 16. 00 16. 40 20. 63 24. 16 49. 59 53. 89 59. 90 The range of figures is rather wide, but the highest values represent tropical streams. That is, leaving artificial pollution out of account, waters flowing through tropical swamps carry the largest proportion of organic matter. Lough Neagh, in Ireland, doubtless shows the effects of bog water. The organic matter is derived from the decay of vegetable sub- stances, and by further oxidation may be converted into carbonic acid and water. Its chemical constitution is not completely known, but it consists in part at least of a vague group of colloidal sub- stances, whose precise nature is yet to be made out. They appear to possess feebly acidic properties, and have therefore received specific names, humic, crenic, apocrenic, and ulmic acids, which terms, how- ever, if not actually obsolete, are at least obsolescent. The salts of these 11 acids” are partly soluble and partly insoluble, and the acids themselves are commonly reputed to be powerful agents in the 108 THE DATA OF GEOCHEMISTRY. solution of rocks . 1 The humus acids are said to decompose silicates , 2 but the evidence is contradictory or at best inadequate. The state- ment, long current in chemical and geological literature, that the acids absorb nitrogen from rain water and the air, and silica from the soil, forming a series of silico-azohumic acids, rests upon the unsup- ported assertions of P. Thenard , 3 who gives no adequate experimental data to sustain his views, which need not be considered further. The observed facts are capable of much simpler interpretation. A comparison of the preceding table with the analyses of river waters generally, will show that waters relatively high in organic matter are likely to be high in silica also. From this it has been inferred that the organic matter holds the silica in solution, although the connection between the two is not invariable. The rivers of British Guiana and the Uruguay are so far the extreme examples of this supposed relation, and the other tropical streams lend support to the view. The humus acids, however, are almost insoluble in water alone, but readily soluble in alkaline solutions. It appears possible, therefore, that the alleged relation between humus and silica is purely coincidental and that the alkalies in the first instance are the really effective solvents. There is no proof that humus acids can dissolve silica when alkalies are absent. As colloids they are more likely to precipitate silica than to bring it into solution. On oxidation, how- ever, they yield carbonic acid, and that in aqueous solution is an active disintegrator of rocks. In fact, the amount of silica in a water is quite independent of organic matter. Many small streams, near their sources, especially if they rise from crystalline rocks, carry a large relative proportion of silica, although its absolute amount may be trivial. This pecu- liarity is shown in many of the analyses cited in the preceding pages, and is so marked that a water low in salinity but relatively high in silica and alkalies may almost certainly be attributed to igneous rather than to sedimentary surroundings. This silica is directly derived from the rocks at the time of their decomposition by car- bonated waters, and forms a large part of the material which is at first taken into solution. The seepage or ground water which after- ward enters the streams is much poorer in silica, and so the propor- tion of the latter tends to diminish as a river flows toward the sea. 1 See A. A. Julien, Proc. Am. Assoc. Adv. Sci., vol. 28, 1879, p. 311. On the organic matter of waters in Finland, see O. Asclian, Zeitschr. prakt. Geologie, vol. 15, 1907, p. 56. On the chemical nature of the organic matter in soils, see O. Schreiner and E. C. Shorey, Bull. Bur. Soils No. 74, U. S. Dept. Agr. See also S. Od6n, Ark. Kem. Min. Geol., vol. 4, No. 26, 1912, and S. L. Jodidi, Join. Franklin Inst., vol. 176, p. 565, 1913. 2 A. Rodzyanko, Jour. Chem. Soc., vol. 62, pt. 2, 1892, p. 1373. Abstract from Jour. Russ. Chem. Soc., vol. 22, p. 208. 2 Compt. Rend., vol. 70, 1870, p. 1412. LAKES AND RIVERS. 109 CONTAMINATION BY HUMAN AGENCIES. In any complete discussion of river waters account must be taken of contamination by human agencies. Towns and factories drain into the streams, and the extent of the pollution is, for our immedi- ate purposes, best measured by the proportion of chlorine. A good example is furnished by the Chicago drainage canal, which empties into the Desplaines River and thence passes through the Illinois River into the Mississippi. For the waters thus affected there are abundant data, and the sanitary analyses by the late A. W. Palmer are especially valuable. 1 His annual averages for 1900, represent- ing Illinois River, are stated below; the percentages have been calcu- lated by me. The localities are arranged in order downstream. Chlorine in Illinois and Mississippi rivers. Total dissolved solids. Chlorine. Illinois River — At Morris Parts 'per million. 235.3 Parts per million. 23.1 Per cent. 9. 82 At Ottawa 269.4 21.4 7. 94 At Lasalle 245.4 18.7 7. 62 At Averyville 245.2 17.5 7.14 At Havana 236.3 14.8 6. 27 At Kampsville 234.3 14.0 5. 98 At Grafton 232.6 13.1 5. 63 Mississippi River at Grafton 150.1 3.1 2.06 The decrease in the proportion of chlorine as we follow the Illinois downstream is most striking; but even more surprising are the data concerning the Mississippi a little farther south, at Alton. Here samples were taken 100 feet from the Illinois shore, one-fourth the distance across, in midstream, three-fourths over, and 100 feet from the Missouri shore. The figures represent averages covering periods of from nine months to nearly the entire year 1900. Chlorine in Mississippi River at Alton, III. Total dissolved solids. Chlorine. 100 feet from Illinois shore Parts per million. 194. 1 Parts per million. 7. 7 Per cent. 3. 97 3. 87 2. 74 One-fourth distance across 182.8 7. 1 Midstream 160. 6 4.4 Three-fourths distance across 155.0 4. 1 2. 65 100 feet from Missouri shore 154.2 3.5 2. 27 i Chemical survey of the waters of Illinois, 1897-1902, Univ. Illinois, 1903. 110 THE DATA OF GEOCHEMISTRY. The influence of the Illinois River on the eastern side of the Missis- sippi is perfectly evident. The chief cause of the diminution of chlorine in the Illinois is, of course, the dilution of the water by other less contaminated sources of supply. In the Kankakee at Wilming- ton the proportion of chlorine during the same period was only 1.21 per cent, and in the Fox River it was 1.98 per cent, calculated from the total matter in solution. The Kankakee and Fox rivers represent an approximation to the normal chlorine of the region; the Illinois, into which they flow, shows the exaggeration produced by artificial means. Near the ocean the normal chlorine in fresh waters is much higher and the effects of pollution are less conspicuous than in inland streams. 1 GAINS AND LOSSES IN WATERS. In fresh-water lakes and rivers the salinity is naturally low — that is, their waters are very dilute solutions, which do not approach the point of saturation for even the less soluble of their constituents. The relatively insoluble carbonates of calcium and magnesium are held in solution by the excess of carbonic acid which is always present, and are therefore to be regarded, while dissolved, as bicar- bonates. Without this solvent much of the load would be deposited, as indeed it is by the evaporation of percolating waters in limestone caves, when stalactites and stalagmites are formed. In a flowing river, which continually receives carbon dioxide from the air and from decaying vegetation, such depositions are not likely to occur, at least not to any notable extent; but when pools are left from an overflow, incrustations of solid matter may soon form. The sedi- ments found in streams are mostly claylike in character, and rarely contain any conspicuous proportion of carbonates or sulphates. Liv- ing organisms, especially corals, mollusks, and some aquatic plants, withdraw calcium carbonate from solution; but how great their influence may be, relatively to an entire flow, we have no means of estimating. Many agencies thus combine to modify the composition of a water, but the relative magnitude of the several factors can hardly be determined. The waters gain and lose solid matter, but on the whole, as we follow a stream downward in its course, the gains exceed the losses. When we exclude the elements of dilution by tributaries and the variations in concentration between high and low stages of water we find that salinity generally increases until a river reaches the sea. Speaking broadly, lake and river waters may be divided into two great classes — namely, sulphate and carbonate waters, according as 1 A good summary of the relations between normal and polluted waters in the eastern and middle States is given by M. O. Leighton in Water-Supply Paper U. S. Geol. Survey No. 79, 1903. The subject of normal chlorine is considered and the classical “chlorine map” of Massachusetts is reproduced. See also Sixth Rept. Rivers Pollution Commission, 1868, on the domestic water supply of Great Britain. This report contains abundant data on chlorine in waters. LAKES AND RIVERS. Ill carbonic or sulphuric ions predominate. The classification can be still further subdivided with reference to the abundance of chlorides or of silica, and again with regard to bases; but the two main divi- sions still hold. Most river waters are either carbonate or sulphate in type, and we have already seen how climatic considerations deter- mine, in part at least, the chemical character of a stream. The car- bonates are derived from the carbonic acid of rain or from that produced by organic matter, which may act either upon crystalline rocks directly or by solution of limestones. The sulphates originate in the oxidation of pyrite or by the solution of gypsum, and the two classes of waters are almost invariably commingled. Carbonate waters are by far the most common, as the cited analyses show, and the reasons for this fact have already been made clear. We have also seen how a river can change its type in flowing from one point to another, and we have noted the probability that this transforma- tion is commonly due to the blending of streams, or even to the accession of ground waters. One other point in this connection re- mains to be noted — namely, the possible influence of micro-organisms. It is more than probable that these minute creatures, acting in pres- ence of other organic matter, may reduce sulphates, with elimination of hydrogen sulphide and the formation of carbonates in their stead. That reactions of this kind occur in saline and brackish waters seems to be well established . 1 A suggestive instance came within the expe- rience of the United States Geological Survey. A quantity of water rich in sulphates, from one of the alkaline lakes of California, was sent to the laboratory in a wooden barrel. When received, the water had become fetid with hydrogen sulphide and discolored by extract from the wood — so much so as to be unfit for analysis. How far such changes may occur in nature, especially in swamp waters, remains to be determined. At all events, the possibility of similar transformations can not be ignored. That bacteria are active agents in precipitating calcium carbonate is well known; but that subject will be considered more fully in another chapter. CHEMICAL DENUDATION. Now, to sum up: A river is formed by the union of waters from many sources, and each one owes its peculiarities to the conditions existing at its starting point. Carbonic acid, either of atmospheric or of organic origin, is the most abundant and generally the most potent of the agents that dissolve mineral matter from the rocks. Hence carbonate waters are the commonest, and, as streams blend to form the great continental rivers, the carbonate type tends to become more and more pronounced. In the temperate zone, at 1 See N. Zelinsky, Jour. Chem. Soc., vol. 66, pt. 2, 1894, abstract, p. 200; also M. W. Beyerinck, idem, vol. 80, pt. 2, abstract, p. 119; and R. H. Saltet and C. S. Stockvis, idem, vol. 80, pt. 2, 1901, p. 265. 112 THE DATA OF GEOCHEMISTRY. least, the larger streams resemble one another chemically, and seem on the average to do pretty much the same chemical work in pretty much the same way. The composition of their waters gives a meas- ure of the effects which they have produced; and if the data were adequate the study of chemical denudation would be both profitable and easy. But the data are not adequate, except for certain areas, and therefore any estimate which may be reached as to the quantity of solid matter annually carried in solution by rivers to the sea must be subject to future revision. It is clear that an analysis of river water, taken at a single point and at one stage of concentra- tion, tells us little or nothing of what the stream as a whole may do. Annual averages of water taken near the mouths of rivers are needed before the problems of chemical denudation can be even approxi- mately solved. For example, Sir John Murray 1 has computed, by averaging the analyses of 19 rivers, not only the total amount of saline matter carried annually to the ocean, but also its composition. But his estimate, published in 1887, was based almost necessarily upon Euro- pean data and to a large extent upon inconclusive analyses. Evi- dence as to the chemical character of the greater American, African, and Asiatic streams was then practically unobtainable, and therefore the computation was only a rough indication of what the truth may be. Data from all the greater river basins of the world are required before we can determine the full significance of chemical denudation. The problem, however, is not entirely hopeless. It can be attacked locally, with reference to specific areas, and a fairly probable approxi- mation to the truth can be made from the evidence which now exists. T. Mellard Reade, 2 for instance, in a well-known investigation, has calculated the amount of solid matter annually dissolved by water from the rocks of England and Wales. Putting the average salinity of the waters at 12.23 parts in 100,000, he estimates that the total annual run-off from the area in question carries in solution 8,370,630 tons of dissolved mineral matter, or 143.5 tons from each square mile of surface. At this rate, by the solvent action of water alone, the level of England and Wales would be lowered 1 foot in 12,978 years. Reade also, from such data as he could obtain, for the most part single analyses, made similar but rough estimates for several European river basins, which, in British tons per square mile, may be tabulated as follows : Rhone 232 Thames 149 Garonne 142 Seine 97 Rhine 92. 3 Danube 72. 7 1 Scottish Geog. Mag., vol. 3, 1887, p. 65. 2 Proc. Liverpool Geol. Soc., vol. 3, 1876-77, p. 211. Reprinted under the title “Chemical denudation in relation to geological time.” LAKES AND RIVERS. 113 The average for the entire land surface of the globe he put at 100 tons per square mile, a figure that was not much better than a guess. 1 From investigations made in the water-resources branch of the United States Geological Survey, lower figures are obtained. By combining the results of careful river gaging with the data for salinity as determined in the laboratory, R. B. Dole and H. Stabler 2 have deduced a table, of which the following is an abridgment. The Great Basin and the Red River of the North are here left out of account. Chemical denudation in the United States. Drainage area. Area drained (square miles). Dissolved solids (tons per square mile). North Atlantic 159, 400 123, 900 142, 100 315, 700 1, 265, 000 175, 000 230, 000 72, 700 130 South Atlantic 94 Eastern Gulf of Mexico 117 Western Gulf of Mexico 36 Mississippi River 108 Laurentian Basin (United States area) 116 Colorado River of Arizona 51 South Pacific 177 North Pacific 270, 000 100 Total 2, 753, 800 a 98 a Short tons of 2,000 pounds. The metric ton equals 2,205 pounds. For the entire United States, 3,088,500 square miles, regarding the denudation of the Great Basin as zero — that is, as not con- tributory to the ocean— the average denudation is estimated by Dole and Stabler as 87 short tons, or 78.9 metric tons per square mile, a figure which is not likely to be much changed by future investigations. It refers, however, only to inorganic matter. If organic impurities are included it should be increased by perhaps 10 per cent; that is, to 86.8 metric tons per square mile. The variation in the denudation factors assigned to the several areas is quite important. The Colo- rado drains an arid region, and much of the area ascribed to the river adds little or nothing to it. The humid basin of the St. Law- rence, on the other hand, is a liberal contributor of saline substances. The Mississippi, with humid regions to the east and semiarid plains to the west, shows an intermediate figure for the chemical erosion. 1 For other estimates of the amount of material carried by various rivers, see A. Geikie, Text-book of geology, 4th ed., vol. 1, 1903, p. 489. The Thames, for example, carries in solution past Kingston 548,230 tons of fixed inorganic matter in a year. See also the thesis of A. F. White on the waters of Rockbridge County, Virginia (Washington and Lee Univ., 1906). This thesis deals with North River, a tributary of the James. 2 Water-Supply Paper U. S. Geol. Survey No. 234, 1909, p. 78. The figures are given in much greater detail than is practicable here. Some of the areas, etc., differ slightly from those cited in previous pages of this book ; but the differences are trivial and do not appreciably affect the final result. The recent (1914) data relative to the Columbia River, etc., are not included in this estimate. 97270°— Bull. 616—16 8 114 THE DATA OF GEOCHEMISTRY. For the rest of North America only a rough estimate is possible. The analyses of Canadian rivers given in previous pages indicate an average composition and salinity much like that of the St. Lawrence. For Mexican and Central American rivers no data are at hand, but it is probable that for northern Mexico, at least, they would resemble those of Texas, New Mexico, and Arizona. That is, the waters north of the United States and south of it vary from the mean found for the United States in opposite directions, and so tend to balance each other. In short, the average for the United States probably represents fairly w r ell the average for the entire continent. If we assume that six millions of square miles in North America lose 79 metric tons in solution per square mile per annum, and that the composition of the saline matter so transported is that found for the United States alone, we shall be fairly near the truth. ^ Evidence for South America is very scanty. On the basis of Frankland’s analysis, Reade 1 estimates the denudation factor of the Amazon at 50 tons per square mile. Using the same analysis, and Murray’s estimate of the total run-off, I find that 53 tons is rather more probable. Similar estimates for the Uruguay and the Negro give a factor of 50 tons. About four millions of square miles in South America may be assigned the latter figure, with a reasonable degree of probability. The Amazon dominates the entire combina- tion, and its low salinity is due to the fact that it drains a vast tropical forest, which is thoroughly leached. Through much of its course it has scanty access to fresh rocks and therefore finds but little material to dissolve. Large areas in South America; like western Peru and central Argentina, contribute nothing to the ocean and count for zero in measuring chemical denudation. 2 Some figures relative to European waters have already been given. According to Geikie the Thames carries in solution past Kingston 548,230 British, or 556,930 metric tons of inorganic matter annually. The drainage area is 6,100 square miles, hence a denudation factor of 91.3 metric tons per square mile. For the Meuse above Liege the figures published by Spring and Prost give a factor of 139 tons. In Sweden the chemical denudation is much smaller, but seems to have been estimated for only a very limited area. Reade’s estimate for all Europe is 100 tons per square mile, and that seems to be fairly probable. For Europe, then, I shall assume that 3,000,000 square miles suffer solvent denudation at the rate of 100 tons per mile, a figure wdiich is not far from that assigned to the Laurentian Basin. Europe is generally well watered, and its waters have all the 1 Evolution of earth structures, London, 1903, pp. 255-282. 2 The rivers of British Guiana are not included in this discussion, which was completed before their analyses were made. LAKES AND RIVERS. 115 characteristics of those from the humid areas of the United States. In the latter the denudation factor is lowered by the arid regions of the Southwest. The African material is very imperfect. According to Chelu, 1 the Nile carries 20,772,400 metric tons in solution annually. This, for an ostensible drainage basin of 1,293,050 square miles, gives a denu- dation factor of only 16 tons. Much of northern Africa resembles the Valley of the Nile so far as denudation is concerned. We may safely assume that 1,500,000 square miles are represented by the Nile, and also that 6,500,000 are equivalent in character to South America with its tropical streams. The desert regions, like the Sahara, of course, are negligible. The data relative to Asiatic waters are even more defective. The water of Lake Baikal resembles that of the St. Lawrence, while the Mahanuddy has the peculiarities of tropical rivers. With these feeble clues I can only make a very rough estimate for Asia, as follows: Assume 3,000,000 square miles to average like Europe, 3,000,000 like the United States, and 1,000,000 like South America. Large areas in Asia are obviously left out of consideration — the Caspian depression, the central deserts, and the Arabian peninsula. The streams reaching the sea from Arabia are too small to carry any weight in the general discussion. To sum up, the crude figures for chemical denudation are as follows : North America 6,000,000 square miles at 79 tons 474,000,000 tons South America 4,000,000 square miles at 50 tons 200,000,000 tons Europe 3,000,000 square miles at 100 tons 300,000,000 tons Asia 7,000,000 square miles at 84 tons 588,000,000 tons Africa 8,000,000 square miles at 44 tons 352,000,000 tons 28,000,000 square miles at 68. 4 tons.. 1,914,000,000 tons The incompleteness of the foregoing figures is due to the fact that large areas of land either do not drain into the ocean, or add little or nothing to it. The total land area to be considered — that is, the area which contributes to the salinity of the ocean — is, according to Murray, 39,697,400 square miles, or, in round numbers, 40,000,000. Assuming that the figures so far given represent a fair average, the amount of saline matter carried into the ocean by the river drainage of the world is 2,735,000,000 metric tons annually, an estimate only a little more than half that given by Murray. 2 The rivers studied by Murray must have been for the most part, if not exclusively, in the Temperate Zone, where alternations of freezing and thawing tend to Le Nil, le Soudan, l’Egypte, Paris, 1891. 2 For more details with reference to these computations, see F. W. Clarke A preliminary study of chem- ical denudation: Smithsonian Misc. Coll., vol. 56, No. 5, 1910. 116 THE DATA OF GEOCHEMISTRY, break up the rocks and so to render them more easily decomposed by percolating waters. With even moderate humidity the activity of the waters is great, and large amounts of material are transported by them. On the other hand, Arctic rivers flow to a noteworthy extent over tundra, which is frozen during the greater part of the year. They therefore have comparatively small influence in rock solution, and much of their flow must be mere surface run-off. The low salinity of tropical streams has already been noted. The total amount of chemical denudation depends upon the balancing of these varying tendencies. With the aid of the foregoing estimates, and of the analyses cited in this chapter, a probable average can be computed for the compo- sition of the fresh waters of the globe. Such an average is shown in the next table. Average composition of river and lake waters. A. Waters of North America. Average computed from the data given by Dole in Water-Supply Paper 236, and by Dole and Stabler in Water-Supply Paper 234. Each analysis is weighted proportionately to the total amount of material annually carried by the river. The alkalies are given with Palmer’s determina- tions of potassium. B. Waters of South America. Average made up from the cited analyses, weighted as follows: Amazon, 12; Uruguay, 1; Negro, 1; all smaller streams, 2. The Rio de la Plata is left out of account, for the analyses are not conclusive. C. Waters of Europe. Average of 300 analyses of river and lake waters, first by groups, and then weight- ing each group proportionately to its drainage area. D. Waters of Asia. Made up of the averages A, B, C, weighted 3 : 3 : 1 as explained in a previous para- graph. E . W aters of Africa. Made up of the average for the N ile and that for South America as already described. F. General average, in which each of the foregoing averages is weighted proportionally to the number of tons given in the preceding table. G. Sir John Murray’s average composition of river water (Scottish Geog. Mag., vol. 3, 1887, p. 65), reduced to the uniform standard adopted in this book. Organic matter as given by Murray is 10.37 per cent of the total solids. , A B C D E F G CO, 33. 40 32. 48 39. 98 36. 61 32. 75 35. 15 41. 33 so 4 15. 31 8. 04 11. 97 13. 03 8. 67 12. 14 8. 22 Cl 7. 44 5. 75 3.44 5. 30 5. 66 5. 68 1. 85 no 3 1. 15 . 62 . 90 . 98 . 58 . 90 2. 82 Ca 19. 36 18. 92 23. 19 21. 23 19. 00 20. 39 20. 46 Mg 4. 87 2. 59 2. 35 3. 42 2. 68 3. 41 4. 65 Na 7. 46 5. 03 4. 32 5. 98 4. 90 5. 79 3. 47 K 1. 77 1. 95 2. 75 1. 98 2. 35 2. 12 1. 33 (Fe,Al)oO, . 64 5. 74 2. 40 1. 96 5. 52 2. 75 4. 76 Si0 2 8. 60 18. 88 8. 70 9. 51 17. 89 11.67 10. 75 Minor constituents .36 Weight 100. 00 10 100. 00 4 100. 00 6 100. 00 11 100. 00 7 100. 00 100.00 The general mean F, regardless of corrections to be considered later, is curiously near the average figures for three great rivers, the Missis- sippi, the Amazon, and the Nile. It may be too high in silica, but on the whole it is as near the truth as can be determined with existing LAKES AND RIVERS. 117 data. Analyses of the greater rivers of Asia and Africa may modify it slightly, but the order of magnitudes shown by the several radicles is not likely to be changed. Recurring now to Reade's estimate of chemical denudation in Eng- land and Wales, a rate of one foot in 12,978 years, the new data may be applied to a similar discussion for the entire land surface of the globe. For the United States, excluding the Great Basin, the denu- dation factor of 79 tons per square mile per annum gives for a lower- ing of one foot 23,984 years. For South America the figures are 50 tons and 37,896 years; for Europe, 100 tons and 18,948 years, and for the Nile Valley, 16 tons and 118,424 years. For the entire, 40, 000, 000 square miles of land the average values are 68.4 tons and 27,700 years; estimates that are subject to corrections of a kind which Reade did not take into consideration. On critical examination of the data it is clear that the total appar- ent amount of solvent denudation is not a true measure of rock decomposition. In the general mean of all the river analyses now under discussion, 0.90 per cent of N0 3 and 35.15 per cent of C0 3 appear. The N0 3 came entirely or practically so from atmospheric sources; the C0 3 was derived partly from the atmosphere and partly from the solution of limestones. Dealing now only with the existing discharge of rivers, we must subtract these atmospheric additions from the total annual load of dissolved inorganic matter before we can compute the real amount of rock denudation. The land surface of the earth is covered, nearly enough for present purposes, by 75 per cent of sedimentary and 25 per cent of igneous and crystalline rocks; 1 and it is on or near this surface that the flow- ing waters act. The limestones, as shown in Chapter I, constitute only one- twentieth of the sediments, or 3.75 per cent of the entire area, but the proportion of carbonates derived from them must be very much larger. The composite and average analyses of rocks give, for lime, 4.81 per cent in the igneous, and 5.42 in all the sedi- mentaries, equivalent to 3.78 and 4.26 per cent of C0 2 respectively. Assuming that all the surface rocks yield lime at an equal rate, which is obviously not quite true, and multiplying these figures by the areas represented as 1 to 3, the relative proportions of the C0 3 radicle become 3.78:12.78, or 1:3.4 nearly. The last figure should be higher, because of the more rapid solution of the limestone, but if we accept the ratio as it stands we may use it to determine the approximate proportions of the C0 3 radicle derived from limestones and from the atmosphere acting upon crystalline rocks. On this basis, 8 per cent of C0 3 should be deducted from the percentage in the river waters, together with the 0.9 per cent of N0 3 . Making the subtraction from 1 Estimate by A. von Tillo, actually 75.7 and 24.3. 118 THE DATA OP GEOCHEMISTRY. the total river load of dissolved matter, 2,735,000,000 tons, there remains 2,491,585,000 tons, or about 62.3 tons per square mile on the average, for the 40,000,000 of square miles of land which are assumed to drain into the ocean. This implies a lowering of the land by solvent denudation at the rate of one foot in 30,414 years, or 30,000 in round numbers. The last estimate may be subject to large future cor- rections, but probably it is correct within 10 per cent. There are, for example, corrections for the amount of chlorine and its equivalent sodium brought in rainfall from the atmosphere, or by sewage from towns. 1 These will be considered in the next chapter in relation to the use of the data in measuring geologic time. 1 Spring and Prost, in their work on the Meuse, and Ullik, in his study of the Elbe, have attempted to measure the amount of human contamination. This, obviously, must be very variable. In rivers like the Yukon or the Colorado it is negligible; in the Mississippi or the Hudson it is doubtless large. In small streams in thickly settled manufacturing districts the amount of pollution is often enormous. CHAPTER IV. THE OCEAN. ELEMENTS IN THE OCEAN. For obvious reasons, some of them purely scientific and some utilitarian, the water of the ocean has been the subject of long and elaborate scientific investigations. Considered broadly, its composi- tion is relatively simple and remarkably uniform; studied minutely, It is found to contain many substances. 1 In his great memoir on the chemical composition of sea water, G. Forchhammer 2 gave a list of the various elements which, up to his time, had been detected in it. The elements which are sufficiently abundant to be determined in ordinary analyses will be considered later; the substances that are less frequently estimated may be briefly considered now. Iodine . — Chiefly found in the ashes of seaweeds. According to E. Sonstadt, 3 it is present in sea water in the form of calcium iodate. The quantity estimated was one part of this salt in 250,000 of water, equivalent to about two parts per million of iodine. A. Gautier, 4 examining surface water from the Mediterranean, found iodine only in the organic matter which he separated by filtration, but at depths beyond 800 meters its compounds were detected in the water itself. Living organisms withdraw iodine from solution. The largest amount of iodine, organic and inorganic, reported by Gautier, is 2.38 milligrams to the liter. J. Koettstorfer, 5 in an earlier investi- gation, found much smaller quantities. Fluorine . — Found directly and also in the boiler scale of oceanic steamers. A. Carnot's determinations 6 show that the water of the Atlantic contains 0.822 gram of fluorine to the cubic meter. 7 Recent 1 For the volume of the ocean and of its contained salts see pp. 23, 24. 2 Philos. Trans., vol. 155, 1865, pp. 203-262. See also J. Roth, Allgemeine und chemische Geologie, vol. 1, 1879, p. 400; and W. Dittmar, Kept. Challenger Exped., Physics and chemistry, vol. 1, 1884, pp. 1-251. A volume by Ren£ Quinton (L’eau de mer, Paris, 1904) contains (pp. 221-235) a good summary of earlier work on the less important elements in sea water. The book is essentially biochemical in character and deals mainly with the relations of sea water to life. 3 Chem. News, vol. 25, 1872; pp. 196, 231, 241; vol. 74, 1896, p. 316. < Compt. Rend., vol. 128, 1899, p. 1069; vol. 129, 1899, p. 9. s Zeitschr. anal. Chemie, vol. 17, 1878, p. 305. e Annales des mines, 9th ser., vol. 10, 1896, p. 175. 7 See also earlier determinations by G. Forchhammer and G. Wilson, Edinburgh New Philos. Jour., vol. 48, 1850, p. 345. 119 120 THE DATA OF GEOCHEMISTRY. determinations by A. Gautier and P. Clausmann 1 gave only 0.3 milli- gram per liter. P. Carles 2 has reported fluorine in the shells of mollusks. Nitrogen. — Present as ammonia, in organic matter, and in dissolved air. The ammonia of sea water has been repeatedly investigated. A. Audoynaud , 3 in water from the coast of France, found 0.16 to 1.22 milligrams of NH 3 per liter. L. Dieulafait , 4 in waters from the Red Sea and the coast of Asia, reports quantities from 0.136 to 0.340 milligram. T. Schloesing 5 found a still larger amount, namely, 0.4 milligram. According to J. Murray and R. Irvine , 6 ammonia is mom abundant around coral reefs than in the North Atlantic or German Ocean. It occurs principally as ammonium carbonate, formed by the decomposition of organic matter. Elaborate determi- nations of ammonia in the Mediterranean are given by K. Natterer . 7 Phosphorus. — Present in the form of phosphates. The phosphatic nodules found on the bottom of the sea are considered farther on in this chapter. Arsenic. — Detected by Daubree. A. Gautier 8 found its quantity to range from 0.01 to 0.08 milligram per liter. Silicon. — According to J. Murray and R. Irvine, 9 sea water con- tains silica. The proportion is from 1 part in 220,000 to 1 in 460,000, or even less. The siliceous organisms which abound in the ocean probably take their silica from clayey matter in mechanical sus- pension. Small amounts of such matter are carried far and wide by currents, often to a great distance from land. E. Raben 10 found sea water to contain from 0.2 to 1.4 milligrams of silica per liter. Boron. — Present in sea water and in the ashes of marine plants. J. A. Veatch , 11 who examined water from the coast of California, found boric acid almost exclusively in samples collected over a sub- marine ridge, parallel with the land but 30 to 40 miles away. He suggests for it a volcanic origin from submerged sources. Lithium. — Reported in sea water by L. Dieulafait . 12 Also detected spectroscopically by G. Bizio in water from the Adriatic. 1 Compt. Rend., vol. 158, 1914, p. 1631. 2 Idem, vol. 144, 1907, pp. 437, 1240. a Idem, vol. 81, 1875, p. 619. * Annales chim. phys., 5th ser., vol. 14, 1878, p. 380. Dieulafait mentions earlier work by Marchand and Boussingault. & Contributions a l’6tude de la chimie agricole, in Fremy’s Encyclopedic chimique, 1888. e Proc. Roy. Soc. Edinburgh, vol. 17, 1889, p. 89. i Monatsh. Chemie, vol. 14, 1893, p. 675; vol. 15, 1894, p. 596; vol. 16, 1895, p. 591; vol. 20, 1899, p. 1. See also E. Raben, Wissenschaftliche Meeresuntersuchungen, vol. 11, Kiel, 1910, p. 303. Many determina- tions are given, also a full summary of earlier work. 8 Compt. Rend., vol. 137, 1903, pp. 232, 374. 9 Proc. Roy. Soc. Edinburgh, vol. 18, 1891, p. 229. Wissenschaftliche Meeresuntersuchungen, vol. 11, Kiel, 1910, p. 311. “ Proc. California Acad. Sci., vol. 2, 1859, p. 7. 12 Annales chim. phys., 5th ser., vol. 17, 1879, p. 377. See also Thorpe and Morton’s analysis of water from the Irish Sea, 1871, cited on p. 123. THE OCEAN. 121 Rubidium. — Found in sea water by Sonstadt. 1 Determined quan- titatively by Schmidt, whose analyses will be cited later. Caesium. — Also found by Sonstadt. 1 Barium and strontium. — Can be detected by ordinary methods. Also found in the ashes of seaweeds and in boiler scale. 2 Aluminum and iron. — Easily detected by direct methods. Manganese. — Easily detected. Noted by Forchhammer and also by Dieulafait. 3 Concretions of manganese oxide are abundant over portions of the sea bottom. Reported by E. Maumene 4 in the ashes of Fucus serratus. Nickel and cobalt. — Found in the ashes of marine plants. Copper. — Repeatedly detected in sea water, especially by Dieula- fait. 5 Also in the ashes of seaweeds and in certain corals. Zinc. — Reported in sea water by Dieulafait. 6 Also found in the ashes of seaweeds. Lead. — Found by Forchhammer in a coral. Silver. — Repeatedly observed. Forchhammer, in the coral above noted, found one part of silver to eight of lead. Malaguti, Durocher, and Sarzeaud 7 found silver to the amount of 0.5 milligram in 50 liters of water and detected copper and lead. According to A. Liversidge, 8 silver is present in sea water to the extent of 1 to 2 grains per ton. Gold. — The fact that sea water contains gold was first established by E. Sonstadt 9 in 1872. Its presence has since been repeatedly verified. In 1892 C. A. Munster 10 examined water from the Kris- tiania Fjord, Norway, and found in it 5 to 6 milligrams of gold, with 19 to 20 of silver, per ton. In each analysis he used 100 liters of water. LN ersidge 11 found the gold in Australian waters to range from 0.5 to 1.0 grain per ton. At either rate, gold is present in the ocean in thousands of millions of tons. Liversidge 12 also detected gold in kelp, rock salt, and a number of saline minerals, such as sylvine, kainite, carnallite, and Chilean niter. In one sample of kelp he found 22 grains of gold per ton, and in a bittern, 5.08 grains. J. R. Don 13 examined both ocean water and oceanic sediments. In 1 Chem. News., vol. 22, 1870, p. 25. 2 On strontium in sea water see Dieulafait, Compt. Rend., vol. 84, 1877, p. 1303. 3 Idem, vol. 96, 1883, p. 718. * Idem, vol. 98, 1884, p. 1417. 5 Annales chim. phys., 5th ser., vol. 18, 1879, p. 359. e Idem, vol. 21, 1880, p. 266. 7 Idem, 3d ser., vol. 28, 1850, p. 129. 8 Proc. Roy. Soc. New South Wales, vol. 29, 1895, pp. 335, 350. See also F. Field, Proc. Roy. Soc., vol. 8, 1856, p. 292. 9 Chem. News, vol. 26, 1872, p. 159. 10 Jour. Soc. Chem. Ind., vol. 11, 1892, p. 351. From Norsk Tekn. Tidsskr. 11 Proc. Roy. Soc. New South Wales, vol. 29, 1895, pp. 335, 350. 12 Jour. Chem. Soc., vol. 71, 1897, p. 298. 13 Trans. Am. Inst. Min. Eng., vol. 27, 1897, p. 615. 122 THE DATA OF GEOCHEMISTRY. the former he detected 0.071 grain of gold per metric ton, but the sediments were barren. In waters collected near the Bay of San Francisco L. Wagoner 1 found, also per metric ton, 11.1 milligrams of gold and 169.5 of silver. In a later paper he gives larger figures, namely, 16 milligrams of gold and 1.9 grams of silver. According to J. W. Pack 2 sea water contains about 0.5 grain of gold per ton. In deep-sea dredgings Wagoner 3 detected even larger quantities of both precious metals. Radium. — Ocean water, sea salt, and oceanic sediments are all more or less radioactive. From measurements of this radioactivity the amount of radium is inferred. 4 According to Joly, 1 cubic centimeter of sea water, on the average, contains 0.017 XlO -12 gram of radium. This represents a total of about 20,000 metric tons of radium in the entire ocean. But is this radioactivity due solely to radium ? COMPOSITION OF OCEANIC SALTS. In order to determine the composition of ocean salts, innumerable analyses have been made, representing water collected in all quarters of the globe. The older investigations, down to and including the work of Forchhammer, are well summarized by Both and it is not necessary to recapitulate them here. With a few exceptions I shall confine myself to the more recent analyses, which are numerous enough and varied enough for all present purposes. They show a striking uniformity in the composition of sea salts, the only great variable being that of concentration. As this factor is large, com- pared with the salinity of lakes and rivers, I shall express it generally in percentages rather than in parts per million. The analyses them- selves I have reduced to ionic form, ignoring bicarbonates, as in the tables given in the preceding chapter. The selected data are as follows: 5 1 Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 807. 2 Min. and Sci. Press, vol. 77, 1898, p. 154. 3 Trans. Am. Inst. Min. Eng., vol. 38, 1907, p. 704. P. De Wilde (Arch. sci. phys. nat., 4th ser., vol. 19, 1905, p. 559) and A. Wiesler (Zeitschr. angew. Chemie, 1906, p. 1795) have published good summaries rela- tive to the detection of gold in sea water and have discussed the possibility of its economic recovery. 4 See It. J. Strutt, Proc. Roy. Soc., vol. 78A, 1907, p. 151; A. S. Eve, Philos. Mag., 6th ser., vol. 18,1909, p. 102; J. Joly, idem, vol. 15, 1908, p. 385; vol. 18, 1909, p. 396. In a volume entitled “Radioactivity and geology, ” London, 1909, pp. 45-58, Joly sums up the relations of the ocean to radium. See also S. J. Lloyd, Am. Jour. Sci., 4th ser., vol. 39, 1915, p. 580. His estimate of radium in sea water is only 1.2 XlO -12 gram per liter, or 1,400 tons in the ocean. 5 Other analyses of Atlantic water, taken off the coast of Brazil, with analyses of water from the mouths of the Amazon, are given by F. Katzer, in Sitzungsb. K. bohm. Gesell. Wiss. 1897, No. 17. These repre- sent mixtures of sea and river water. For special determinations of bro min e in sea water, and its ratio to the chlorine, see E. Berglund, Ber. Deutsch. chem. Gesell., vol. 18, 1885, p. 2888. An analysis of water from the Ionian Sea, by F. Wibel, is printed in Ber. Deutsch. chem. Gesell., vol. 6, 1873, p. 184. One by A. Vierthaler (Sitzungsb. K. Akad. Wiss. Wien, vol. 56, 1867, p. 479), of Adriatic water taken nearSpalato, shows abnormally low sodium and high calcium, presumably due to admixtures of water from the land. See also W. Skey, Third Ann. Rept. Colonial Mus. and Lab., New Zealand, 1868, for seven analyses of sea water taken near that island; C. J. White, Proc. Roy. Soc. New South Wales, vol. 41, 1907, p. 55, one analysis of water taken off Coogee; A. Burada, Ann. sci. Univ. Jassy, vol. 5, 1909, p. 251, one analysis of water from the Black Sea. On salinity of the Persian Gulf, Annalen d. Hydrographic, vol. 7, 1908, p. 293. Two recent analyses of Adriatic water are reported by V. Gegenbauer, Min. pet. Mitt., vol. 29, 1910, p. 357. THE OCEAN, 123 Analysis of oceanic salts. A. Mean of 77 analyses of ocean water from many localities, collected by the Challenger expedition. W. Dittmar, analyst. Challenger Kept., Physics and chemistry, vol. 1, 1884, p. 203. Salinity 3.301 to 3.737 per cent. B. Atlantic water, mean of 22 samples collected on a voyage from the Cape of Good Hope to England. C. J. S. Makin, Chem. News, vol. 77, 1898, pp. 155, 171. Salinity, average, 3.631 per cent. C. The Atlantic near Dieppe. Analysis by T. Schloesing, Compt. Rend., vol. 142, 1906, p. 320. Salinity 32.420 grams per liter. D. The Irish Sea. Analysis by T. E. Thorpe and E. H. Morton, Liebig’s Annalen, vol. 158, 1871, p. 122. The small amounts of Fe 2 C> 3 , NH 3 , and N 2 O 5 are here added together. A trace of lithium was also reported. E. The Baltic Sea between Oeland and Gothland. Analysis by C. Schmidt, Bull. Acad. St. Peters- burg, vol. 24, 1878, p. 231. In all Schmidt’s analyses the bicarbonates given by him have been here reduced to normal salts. The quantities of Fe, PO 4 , and Si02 found by Schmidt are so small that I have added them together. Salinity of this sample, 0.7215 per cent. F. The Atlantic at Bahia Blanca, coast of Argentina. Mean of two samples, taken at low and high tide. Analyses by E. H. Ducloux, An. Soc. cient. Argentina, vol. 54, 1902, p. 62. Salinity, 3.365 per cent. Another pair of analyses is given of water taken at the mouth of Rio Negro. G. The Gulf of Mexico, off Loggerhead Key, near Florida. Analysis by G. Steiger, laboratory of the U. S. Geological Survey, 1910. Salinity, 3.549 per cent. H. From near Beaufort, North Carolina. Mean of five analyses of samples taken under varying con- ditions, by A. S. Wheeler, Jour. Am. Chem. Soc., vol. 32, 1910, p. 646. Salinity, 3.179 to 3.607 per cent. Wheeler cites an analysis by C. Herbst of Mediterranean water. A B c D E F G H Cl 55. 292 55. 185 55. 04 55. 21 55. 01 54. 62 55. 24 55. 25 Br . 188 . 179 . 19 . 19 . 13 . 17 S0 4 7. 692 7. 914 7. 86 7. 69 8. 00 8. 01 7. 54 7. 56 CO, . 207 . 213 . 18 . 09 . 14 . 27 . 34 . 37 0 Na 30. 593 30. 260 30. 71 30. 82 30. 47 30. 20 30. 80 30. 76 K 1. 106 1. 109 1. 06 1. 16 . 96 2. 10 1. 10 1. 14 Eb .04 Ca 1. 197 1. 244 1. 27 1. 21 1. 67 1. 36 1. 22 1. 22 Mg 3. 725 3. 896 3. 69 3. 61 3. 53 3. 36 3. 59 3. 70 Fe, Si0 2 . P0 4 .05 Fe, NH 4 ; N0 3 .02 (Fe,Al)oO,, SiOo .08 100. 000 100. 000 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 124 THE DATA OF GEOCHEMISTRY. Analysis of oceanic salts — Continued. I. The north Atlantic between Norway, the Faroe Islands, and Iceland, and northward to Spitzbergen. Mean of 51 incomplete analyses by L. Schmelck, Den Norske N ordhavs-Expedition, pt. 9, 1882, p. 1 . Soda and carbonic acid estimated by calculation, not directly determined. Salinity, 3.37 to 3.56 per cent. J. The White Sea. Average of three analyses by C. Schmidt. Bull. Acad. St. Petersburg, vol. 24, 1878, p. 231. Salinity, 2.598 to 2.968 per cent. K. The Arctic Ocean between the White Sea and Nova Zembla. Mean of two analyses by Schmidt, loc. cit. L. The Siberian Ocean. Water collected by the Vega expedition. Mean of four analyses by Forsberg, Vega Exped. Rept., vol. 2, 1883, p. 376. Salinity, 1.378 to 3.457 per cent. M. The Mediterranean near Carthage. Analysis by T. Schloesing, Compt. Rend., vol. 142, 1906, p. 320. Salinity, 38.9744 grams per liter. N. The Mediterranean, midsea, between Bizerta and Marseille. Salinity, 38.789 grams per liter. Analy- sis by Schloesing, loc. cit. O. The eastern Mediterranean, waters collected during the voyages of the Austrian steamer Pola. Ana- lyst, K. Natterer, Monatsh. Chemie, vol. 13, 1892, pp. 873, 897; vol. 14, 1893, p. 624; vol. 15, 1894, p. 530. Three hundred samples of water were examined, some only for gases. The figures given here are the aver- age from 42 analyses which were fairly complete. Salinity, 3.836 to 4.115 per cent. P. The Sea of Marmora. Natterer, Monatsh. Chemie, vol. 16, 1895, p. 405; 44 partial analyses. Natterer gives the figures here utilized as averages of varying numbers of determinations. Mg, Na, and K not determined. Salinity, 2.310 to 4.061 per cent. I J K L M N O P Cl \55. 46 55. 22 55. 30 155. 45 55. 53 55.11 55. 30 55. 45 Br / . 14 . 14 j . 18 .19 .16 . 17 S0 4 7. 59 7. 88 7. 78 7. 79 7. 74 7. 89 7. 72 7. 67 C0 3 . 30 . 10 . 07 . 19 . 20 . 19 . 28 Na 30. 53 30. 65 30. 85 30. 41 30. 37 30. 64 30. 51 K 1. 12 . 93 . 89 1. 17 1. 09 1. 09 1. 12 Rb... . 04 . 04 Ca 1. 21 1. 21 1. 16 1. 18 1. 26 1. 23 1. 19 1. 22 Mg 3. 79 3. 75 3. 69 3. 82 3. 64 3. 65 3. 81 Fe, Si0 2 , P0 4 ^ . . 08 . 08 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 THE OCEAN. 125 Analysis of oceanic salts — Continued. Q. The Black Sea. Average of six analyses by S. Kolotoff, Jour. Russ. Phys. Chem. Soc., vol. 24, 1893, p. 82. Salinity, 1.826 to 2.223 per cent. R. The Suez Canal at Ismailia. Analysis by C. Schmidt, Bull. Acad. St. Petersburg, vol. 24, 1878, p. 231. Salinity, 5.103 per cent. For other data on the Suez Canal, see L. Durand-Claye, Annales chim. phys., 5th ser., vol. 3, 1874, p. 188. Very high salinities were noted. For a recent, incomplete analysis of Red Sea water, see J. B. Coppock, Chem. News, vol. 96, 1907, p. 212. S. The Red Sea near the middle. Analysis by Schmidt, loc. cit. Salinity, 3.976 per cent. T. The Red Sea. Average of four analyses by Natterer, Monatsh. Chemie, vol. 20, 1899, p. 1; vol. 21, 1900, p. 1037. Water collected in the Suez Canal, the Timsah Lake, and the two Bitter Lakes. Many other partial analyses are given. The salinity of these particular samples ranged from 5.085 to 5.854 per cent. U. The Straits of Malacca. Salinity, 2,7965 per cent. V. The China Sea. Salinity, 3.208 per cent. W. The Indian Ocean, mean of two analyses, salinity 3.5534 to 3.6681 per cent. Analyses U, V, W, by C. Schmidt, Mel. phys. chim., vol. 10, p. 594. Also Jahresb. Chemie, 1877, p. 1370. Schmidt’s rubidium determinations need verification. X. The “Mare Morto,” an inclosed body of water on the island Lacromo in the Adriatic, having under- ground connection with the sea. Salinity, 3.1744 per cent. Analysis by W. Loebisch and L. Sipocz, Min. Mitt., 1876, p. 171. Q R s T U V W X Cl 55. 12 55. 59 55. 60 55. 96 55. 46 55. 43 55. 41 54.78 Br . 18 . 14 .13 . 18 . 13 . 13 . 13 .26 S0 4 7. 47 7. 67 7. 65 7. 49 7. 91 7. 76 7. 79 7. 60 C0 3 .46 .01 .02 . 13 .04 .03 .05 . 72 Na. 30. 46 31. 21 30. 81 30. 31 30. 23 30. 67 30. 89 30. 57 K 1. 16 .64 .97 1. 06 .94 .97 .85 1. 11 Rb . 03 .04 .03 . 04 . 03 Ca 1. 41 1. 05 .89 1. 22 1. 19 1. 19 1. 16 1. 25 Mg 3.74 3. 64 3. 87 3. 65 4. 03 3. 75 3. 67 3. 71 Fe, S10 2 , P0 4 . 02 .02 . 04 . 03 . 02 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Some of the differences between the foregoing figures are no larger than can be ascribed to differences in analytical methods or in the atomic-weight factors used for calculation. The waters of the Baltic and Black Seas, with their very low salinity, show the effect of dilu- tion by fresh water, which appears in the slightly higher percentage of calcium. Still, allowing for all possible sources of divergence, the essential uniformity in composition of ocean salts is perfectly clear. The mass of the ocean is so great, and the commingling of its waters by winds and currents is so thorough, that the local changes produced by the influx of rivers are exceedingly small. The salinity may range from less than 1 to over 4 per cent, but the saline composi- tion remains practically the same. For the composition of ocean salts in general, Dittmar’s average should be taken as the standard of comparison. It represents the largest number of complete analyses and the greatest refinement of methods; the samples examined covered the widest geographic range and were drawn from various depths of water. Some were surface specimens, others from the bottom of the sea, and still others from 126 THE DATA OF GEOCHEMISTRY. points between, and all the results lead to the same general conclusion of nearly uniform composition, in spite of variable salinity. The individual analyses vary but little from the mean. The salinity is shown to be a function of temperature, pressure, and density; and the last factor is represented by J. Y. Buchanan’s elaborate determina- tions, which appear in the same volume with Dittmar’s analyses. 1 In general, according to the summary given in the “Narrative” of the Challenger expedition, 2 the density and therefore the salinity of ocean water diminishes from the surface to a depth of 800 to 1,000 fathoms, and then increases to the bottom. Toward both poles there are areas of concentration due to the formation of ice, a process which removes water from liquid circulation, leaving a large part of its salts behind. Freezing, as O. Pettersson 3 has shown, modifies the compo- sition of salt water, so that the brine formed from melting ice differs notably from the parent solution. Two analyses by Forsberg 4 serve to illustrate this point. Both are here reduced to standard form in order to facilitate comparison with those of normal sea water. Analyses of brine from melting ice. A. Liquid intermingled with snow, collected on Arctic ice at — 32°. B. Another sample free from snow, also collected at — 32°. A B Cl+Br 62. 47 63. 52 S0 4 1. 26 . 82 Na 25. 88 27. 85 K . 97 1. 06 Ca 2. 00 1. 51 Mr 7. 42 5. 24 100. 00 100. 00 The elimination of sulphates and the increase of chlorides is here clearly indicated, and if we refer back to the tables previously given we shall see that the Arctic waters are all slightly higher in sulphates than Dittmar’s average for the great oceans. In one sense the salinity of sea water is a function of climate, at least so far as surface waters are concerned. Where the rainfall is slight and the evaporation rapid, concentration occurs; where the atmosphere is saturated with moisture the reverse is true. The Bed Sea shows the maximum effect of evaporation and the highest 1 Natterer also, in the memoirs already cited, discusses the relations between density and salinity. So, too, does H. Tomoe in Den Norske Nordhavs-Expedition, 1880. See also memoirs by A. Bouquet de la Grye, Annales chim. phys., 5th ser., vol. 25, 1882, p. 433; and A. Chevallier, Compt. Rend., vol. 140, 1905, p. 902. On this theme there is an extensive literature, but physical problems can be only incidentallycon- sidered in the present memoir. 2 Vol. 2, 1882, pp. 948-1003. 8 Vega Exped. Rept., vol. 2, 1883, pp. 349-380. * See O. Pettersson, op. cit., 1883, p. 376. THE OCEAN. 127 salinity; the Mediterranean is next in order. West of the Nile no large rivers enter the Mediterranean; the evaporation along the African shore is very great, and the salinity is therefore excessive. Furthermore, rainfall serves to dilute the superficial layers of the ocean, and the same effect is produced by the influx of streams. The Black Sea, for instance, is diluted by the Danube, and its average salinity barely exceeds 2 per cent. When a river enters the ocean its waters tend to flow upon the surface, and its influence may be detected at great distances, sometimes hundreds of miles from land. Salinity, in short, is the product of many agencies, and the commingling of waters is never quite complete. In view of conditions like these the nearly uniform composition of sea salts is all the more striking. It is commonly assumed that the salts of the ocean are derived from the decomposition of rocks by flowing and percolating waters, which finally deposit their burden in the great general reservoir. That this opinion is in a very large measure correct is unquestion- able; whether it is wholly true, without qualification, is another matter. We have already seen, in the preceding chapter, that an enormous mass of soluble salts is annually discharged by rivers into the sea, but its composition is very different from that of the saline substances which we are now considering. In the one class of waters carbonates and calcium prevail; in the other we find mainly chlo- rides and sodium. If, then, ocean water is continually receiving water unlike itself, its composition must be slowly changing, but the gains, although large in themselves, are relatively small in compari- son with the vast accumulations of saline matter into which they diffuse. Whatever changes may take place must proceed very slowly, and no known methods of analysis are delicate enough to detect them, even were the observations to be continued through many centuries. For instance, calcium is one of the minor con- stituents of sea water, and yet J. Murray and K. Irvine 1 estimate that the discharge of rivers would require 680,000 years to make up the total oceanic amount. 2 Practically, then, the composition of the ocean is very nearly con- stant and has been so for long periods of time. We can not, by means of analysis, measure the changes in it, but we can observe some of them in operation, and see whither they tend. They are due either to gains or losses of material, and both conditions have been noted in the preceding pages. The gains from rivers and from rain- fall are obvious; the losses by precipitation we shall examine presently. Some salts, as we observed in studying the atmosphere, are lifted from the ocean to fall again, partly upon the land, in rain. Much of 1 Proc. Roy. Soc. Edinburgh, vol. 17, 1889, pp. 100-101. 2 For a statistical paper on the mineral matter in the sea, see R. D. Salisbury, Jour. Geology, vol. 13, . 1905, p. 469. See also A. C. Lane, Jour. Geology, vol. 14, 1906, p. 221, and A. B. Macallum, Trans. Canadian Inst., vol. 7, 1903, p. 535. 128 THE DATA OF GEOCHEMISTRY. this material returns into the sea, but we can not assume that all of it is regained. This loss, however, is trifling, and needs no further consideration here. Streams bring more chlorine and more sodium into the ocean than it loses through the mechanical action of the air. For these constituents a small net gain may safely be taken for granted. As for the changes in composition produced in sea water by freezing, they are local and transitory in character. When the ice melts, its saline contents are restored to oceanic circulation, although not always at the point from which they were withdrawn. To the slight change thus produced in Arctic waters reference has already been made. CARBONATES IN SEA WATER. Although calcium and carbonic acid are subordinate constituents of sea water, their importance can hardly be overestimated. They are the chief additions made by rivers to the ocean, and they are the substances most largely withdrawn from it by living organisms. Removed from solution, they form calcium carbonate, and that is the principal material of corals and shells. Normal calcium carbonate is nearly but not quite insoluble in water. Upon this point many observations have been made. Ac- cording to T. Schloesing, 1 whose data appear to be trustworthy, a liter of water at 16° can dissolve 0.0131 gram of CaC0 3 . With respect to sea water, however, the different varieties of the carbonate behave differently. This has been shown by R. Irvine and G. Young, 2 who found that amorphous calcium carbonate is more soluble than the crystalline forms. To dissolve 1 part of the former 1,600 parts of sea water are required, as compared with 8,000 parts for the crystal- line carbonate. This difference bears directly upon the theory of coral reefs. The living animal secretes amorphous carbonate, but after decomposition a partial change to crystalline carbonate occurs. Without this molecular rearrangement the coral would much more largely dissolve and its stability would be greatly diminished. Some re-solution, however, occurs, especially where the waves have beaten the coral into sand, and this subject has been well studied by J. Murray and R. Irvine. 3 They find that the porous corals dissolve more readily than the compact varieties. In presence of free carbonic acid, the solubility of calcium carbonate is increased many fold. If we disregard ionization we may say that calcium bicarbonate, CaH 2 C 2 0 6 , is then formed, a compound which is chiefly known in solution. Of this salt, as shown by F. P. Treadwell 1 Compt. Rend., vol. 74, 1872, p. 1552. 2 Proc. Roy. Soc. Edinburgh, vol. 15, 1888, p. 316. For other data on the solubility of calcium carbonate in sea water, see W. S. Anderson, Proc. Roy. Soc. Edinburgh, vol. 16, 1889, p. 318; and J. Thoulet, Compt, Rend., vol. 110, 1890, p. 652. 8 Proc. Roy. Soc. Edinburgh, vol. 17, 1889, p. 79. THE OCEAN. 129 and M. Reuter, 1 a liter of pure water at 15° can dissolve 0.3850 gram, a quantity which may he considerably increased by an excess of carbon dioxide in the water. In sea water this solubility is modified by the presence of other compounds. E. Cohen and M. Raken, 2 experimenting with an artificial sea water, found that at 15° it was saturated by 55.6 milligrams of fixed C0 2 per liter, equivalent to 0.1264 gram of CaC0 3 . According to G. Linck, 3 the maximum solubility of calcium carbonate in sea water at 17 Q -18° is 0.191 gram per liter. The total quantity of calcium carbonate in average sea water, as shown by Dittmar’s analyses, and upon the assumption that all of the C0 3 radicle is thus combined, is not far from 0.121 gram per liter. This, which is a maximum, is even below the saturation figure given by Cohen and Raken, and much lower than that of Linck. It would be diminished by the formation of other carbonates, and it must vary with fluctuations in the free or half-combined carbonic acid of the water. The latter constituent of sea water does ^not appear in the analyses of dried oceanic salts. Calcium bicarbonate is very unstable and can be broken down to normal carbonate and free carbon dioxide by evaporation, by rise of temperature, or by mechanical agitation. 4 Under certain conditions the carbonate thus produced may assume the solid form and be pre- cipitated as a sort of calcareous ooze. This, however, can take place only in very shallow waters, and especially near the mouths of streams which carry carbonates in maximum amount. Such a deposition of calcium carbonate, forming a crystalline limestone, was long ago observed in the delta of the Rhone; and a similar reaction is taking place among the Florida keys. Sea water, however, is not saturated with carbonates, and a precipitate forming on the surface of the open ocean would be redissolved before it could settle to the bottom. Even shells undergo solution, and in sufficiently deep water they may entirely disappear. In the reports of the Challenger expedition there is much valuable information on this point. 5 6 Pteropod remains were never found on the ocean floor at depths below 1,500 fathoms, but the more resistant globigerina was collected at 2,500 fathoms. These animals live at or near the surface; after death the shells slowly sink, and, while sinking, partially or wholly dissolve. The decay of their organic matter generates abundant carbonic acid, and this aids in effecting solution. Be this as it may, the Challenger investigations show that the quantity of calcium carbonate on the bottom of the 1 Zeitschr. anorg. Chemie, vol. 17, 1898, p. 170. 2 Proc. Sec. Sci., Amsterdam Acad., vol. 3, 1901, p. 63. 3 Neues Jahrb., Beil. Bd. 16, 1903, p. 505. A recent paper on the solubility of calcium carbonate, by J. Kendall, is in Philos. Mag., ser. 6, vol. 23, 1912, p. 958. * W. Dittmar, Challenger Rept., Physics and chemistry, vol. 1, 1884, p. 211. 6 See summary in vol. 2 of the Narrative, 1882, pp. 948 et seq. 97270°— Bull. 616—16 9 130 THE DATA OE GEOCHEMISTRY. ocean depends in great measure upon the depth of water. Beyond the limits indicated little calcium carbonate is found, a fact which will be considered more in detail presently. Calcium carbonate, then, takes part in a great system of cnanges whose magnitude and direction can hardly be estimated. It enters the sea in fresh waters; part of it is withdrawn by living animals to form coral or shell; some of the material thus used is redissolved, but much of it is permanently deposited in limestones or calcareous shales. Limestone formations of marine origin, in all quarters of the globe, testify to the importance of these processes. Living animals secrete more calcium carbonate than is redissolved , 1 but the inflow of fresh waters tends to supply the loss. Whether a balance is pre- served it is impossible to say. The problem is complicated by the fact that the erosion of limestones laid down in former geologic pe- riods now supplies material to streams, thus returning to the ocean carbonates which were once withdrawn from it . 2 In this system of gains and losses some otherwise unimportant constituents of sea water play an interesting part. Radiolarians, diatoms, and siliceous sponges extract silica from the ocean; this material is finally deposited upon the sea floor, and does not redissolve, or at least not readily . 3 The silica brought in by rivers is partly dis- posed of in this way. Phosphates are also withdrawn, but the bony parts of marine creatures, after the death of the latter, go to a great extent into solution again. Iron, silica, and some potassium are laid down in the form of glauconite; and the substances dredged up from the bottom of the ocean tell us of still other reactions which are not easy to explain. OCEANIC SEDIMENTS . 4 On the subject of oceanic sediments there is a voluminous literature. A great part of it relates to what may be called mechanical deposits, like gravel, sand, river silt, and so on — a class of substance that does not concern us now. Their chemical character will be discussed else- where, with reference to their origin. Near land, and especially at the mouths of rivers, the sea bottom is covered mainly by mechanical sediments, or by the remains of marine animals; in mid-ocean the deposits are of a very different type. An entire volume of the Challenger reports, by J. Murray and A. F. Renard, is devoted to the subject of “ Deep-sea deposits,” and 1 See J. Murray and R. Irvine, Proc. Roy. Soc. Edinburgh, vol. 17, 1889, p. 79. 2 On the circulation of calcium carbonate, and its relation to the age of the earth, see E . Dubois, Proc. Sec. Sci., Amsterdam Acad., vol. 3, 1901, pp. 43, 116. a The insolubility of silica in sea water is great but not absolute. J. Murray and A. F. Renard (Chal- lenger Rept., Deep-sea deposits, 1891, p. 288) find that some silica can be dissolved out from diatomaceous ooze. * A recent treatise by L. W. Collet (Les depots marins, Paris, 1908) deals with this subject quite fully. THE OCEAN. 131 special attention is paid to substances formed by chemical action on the ocean floor. 1 The larger deposits may be classified as follows: Deposits on the ocean floor. Name. Average depth in fathoms. Percentage of CaC0 3 . Red clay 2, 730 2, 894 1, 477 2,049 1,044 6. 70 4. 01 22. 96 64. 47 79. 25 Radiolarian ooze Diatom ooze Globigerina ooze Pteropod ooze The oozes derive their names from the characteristic organic remains which they contain, and they merge by slight gradations one into another. The classification is obviously approximate, not absolute. If we consider them together, and include the coral muds, the average percentage of calcium carbonate upon the sea bottom at various depths is as follows: Variation of calcium carbonate with depth. Per cent. Under 500 fathoms 86. 04 500 to 1,000 fathoms 66. 86 1,000 to 1,500 fathoms 70. 87 1,500 to 2,000 fathoms 69. 55 Per cent. 2.000 to 2,500 fathoms 46. 73 2.500 to 3,000 fathoms 17. 36 3.000 to 3,500 fathoms 88 3.500 to 4,000 fathoms None- The disappearance of carbonates with increasing depth is thus clearly shown. Of all these deposits, the red clay, which covers about 51,500,000 square miles, is the most extensive, and from a chemical point of view, the most interesting. It is universally distributed in the oceanic basins, but is typical only at depths ranging from 2,200 to 4,000 fathoms and far from land. Various theories have been proposed to account for its formation; but Murray and Renard look on it as essen- tially a chemical deposit, produced by the decomposition of silicates of volcanic origin. Remnants of volcanic rocks are found on nearly all parts of the ocean floor, and fragments of pumice are particularly common. Some of these doubtless came from ordinary subaerial vol- canoes, either as direct flows into the ocean, or as volcanic dust borne long distances by currents of air. Other fragments represent sub- marine volcanoes. Some of the specimens studied by Murray and Renard were quite fresh, others were largely decomposed; and in a number of them zeolites had been formed by subaqueous alteration. Crystals of phiflipsite were repeatedly identified. The color of the clay is due to ferric oxide or hydroxide, which is easily removable by 1 See also J. Murray, Geog. Jour., vol. 19, 1902, p. 691; on material collected in 1901 by S. S. Britannia. 132 THE DATA OF GEOCHEMISTRY. means of strong acids. In all essential respects the clay resembles the residues formed by the decay of igneous rocks. Its composition, as shown by many analyses, is extremely variable. That sea water will attack and dissolve silicates is well known, although its efficiency is less than that of fresh water. On this subject the experiments of J. Thoulet 1 have been often quoted and A. Johnstone 2 has shown that even so refractory a mineral as talc is slowly but perceptibly soluble. The process of change is of course almost inconceivably slow; but in the quiet depths of the ocean it has doubtless been going on throughout all geological time. It began when the first volcanic eject amenta entered the sea, if such a moment can be imagined, and has been operative continuously to the present day. Cosmic and other dusts have contributed something to the formation of the clay, and so, too, have animal remains; but volcanic matter seems to have been the chief starting point. This is the view of Murray and Renard, and it is the opinion best sustained by chemical evidence. Possibly, however, submarine volcanoes must also be taken into account. In addition to the widespread formations mentioned in the fore- going paragraphs, the sea bottom yields many interesting products of a sporadic or local character. Among them are the well-known manganese and phosphatic nodules and glauconite; and these we may briefly consider in regular order. Manganese, . as oxide or hydroxide, exists in all deep-sea deposits, sometimes as grains in the clay or ooze, sometimes as a coating upon pumice, coral, shells, or fragments of bone, and often in the form of nodular concretions made up of concentric layers about some other substance as a nucleus . 3 Even in shallow waters, as in Loch Fyne in Scotland, these nodules have been found , 4 but they seem to be more characteristic of the deeper ocean abysses, whence the dredge often brings them up in great numbers. The origin or mode of formation of the manganese nodules is still in doubt. Murray 5 regards the manganese as derived, like the red clay, from the subaqueous decomposition of volcanic debris. C. W. Giimbel 6 attributes the nodules to submarine springs holding manga- nese in solution, which is precipitated on contact with sea water. Buchanan 7 invokes the reducing agency of organic matter, which transforms the sulphates of sea water to sulphides, precipitating iron 1 Compt. Rend., vol. 108, 1889, p. 753. See also recent work by J. Joly, in Compt. rend. Vni. Cong. g6oL internat., 1900, p. 774. 2 Proc. Roy. Soc. Edinburgh, vol. 16, 1889, p. 172. 2 For full description see Challenger Rept., Deep-sea deposits, 1891, pp. 341-378. See also J. Murray and R. Irvine, Trans. Roy. Soc. Edinburgh, vol. 37, 1895, p. 721. 4 J. Y. Buchanan, Proc. Roy. Soc. Edinburgh, vol. 18, 1890, p. 19. b Proc. Roy. Soc. Edinburgh, vol. 9, 1876, p. 255. 6 See abstract in Neues Jahrb., 1878, p. 869. 7 Proc. Roy. Soc. Edinburgh, vol. 18, 1890, p. 17. THE OCEAN. 133 and manganese in the latter form to be subsequently oxidized. This view was contested by R. Irvine and J. Gibson, 1 who showed that manganese sulphide was decomposed by sea water, the manganese redissolving as bicarbonate. J. B. Boussingault 2 holds that the man- ganese was derived from carbonates carried in solution by oceanic waters and a similar explanation has been offered by L. Dieulafait. 3 The oxidation of the carbonates is supposed to take place at the sur- face, through atmospheric contact, after which the precipitated oxide falls to the bottom of the sea. Of all these theories, that of Murray seems to be the best substan- tiated. The manganese can easily be derived from the alteration of rock fragments, as it is by weathering on land; it goes into solution as carbonate, is oxidized by the dissolved oxygen of the sea water, and is precipitated near its point of derivation around any nuclei which happen to be at hand. The nodules occur in close association with altered volcanic materials, and most abundantly in connection with the red clay of similar origin; furthermore, their impurities are of the kind which the suggested mode of formation would lead us to expect. In composition the nodules vary widely, ranging from 4.16 to 63.23 per cent of manganese oxide. The analysis by J. Gibson 4 is the most complete one among the many which were made, and is therefore selected as representative. The entire sample contained — Water 29. 65 Aqueous extract 5 2. 44 Insoluble residue 17. 93 Portion soluble in HC1 49. 97 99. 99 1 Proc. Roy. Soc. Edinburgh, vol. 18, 1890, p. 54. 2 Annales chim. phys., 5th ser., vol. 27, 1882, p. 289. s Compt. Rend., vol. 96, 1883, p. 718. 4 Challenger Rept., Deep-sea deposits, 1891, pp. 417-423. 6 Saline matter unavoidably inclosed in the nodules. Gibson gives its composition in detail. 134 THE DATA OF GEOCHEMISTRY. The insoluble and soluble portions, recalculated separately, are represented in the subjoined statement: Analysis of manganese nodule. Portion soluble in HC1. Insoluble portion. Si0 2 74. 58 Ti(>2 . 72 A1 2 0 3 6. 34 12. 93 Fe 2 0 3 26. 97 4. 79 mAk 4. 60 CaO 4. 02 1. 45 SrO . 11 BaO .67 MnO 42. 94 NiO 1. 96 CoO . 56 ZnO .20 CuO . 74 PbO . 10 TLO .06 Na^jO 3. 62 K 2 0 .95 P 9 0, .22 .11 VXb . 14 Mo0 3 .20 so 3 .94 co 2 .58 Peroxide oxygen 9. 42 99. 99 99. 93 If we include in this analysis the water of the original material we see that it represents a mixture of manganese, iron, and aluminum hydroxides, soluble in hydrochloric acid, with an insoluble residue of silicates. The specimen came from a depth of 2,375 fathoms. The phosphatic concretions found on the ocean floor offer a sim- pler problem for solution. As Murray and Renard 1 show, they are directly derived from the “ decaying bones of dead animals, upon wdiich carbonic acid exerts a powerful solvent action.” They form, like the manganese nodules, around various nuclei, but preferably upon organic centers, such as shells. In many cases the phosphatic matter was first deposited in cavities of shells, around which the nodules continued to grow, inclosing various muddy impurities. Probably the ammoniacal salts which are generated by the decompo- sition of organic matter in the bone play some part in the precipita- tion of the calcium phosphate. The following analyses, by Klement, show the composition of these bodies. A was from a depth of 150 and B from 1,900 fathoms. 1 Challenger Rept., Deep-sea deposits, 1891, pp. 397-400. On the phosphatic nodules of the Agulhas Bank, see L. W. Collet, Proc. Roy. Soc. Edinburgh, vol. 25, 1905, p. 862; and L. Cayeux, Bull. Soc. gdol. France, 4th ser., vol. 5, 1906, p. 750. THE OCEAN. 135 Analyses of phosphatic concretions from sea bottom. A B p 0 o, 19. 96 23. 54 co 2 12. 05 10. 64 so 3 1. 37 1.39 Si0 2 1. 36 2. 56 CaO 39. 41 40. 95 MgO .67 .83 Fe o 0, 2.54 2. 79 A1,0, 1. 19 1. 43 Loss on ignition Undet. 3. 65 Insoluble residue 17. 34 11. 93 95. 89 99. 71 Analyses of the insoluble residue gave the following results : Analyses of insoluble residue from phosphatic concretions. A B Si0 2 77. 43 76. 58 A1 2 0 3 12.40 13. 85 Fe 9 0 3 7. 91 7. 93 CaO 1. 07 1. 27 MgO 1. 02 1. 18 99. 83 100. 81 The concretions, then, consist mainly of calcium phosphate and carbonate, mixed with sand and clay. The last of the oceanic deposits which we need to consider in this connection is glauconite, a hydrated silicate of potassium and ferric iron. It is widely disseminated upon the sea bottom, but most abun- dantly in comparatively shallow waters and near the mud line sur- rounding continental shores — that is, it is formed “just beyond the limits of wave and current action, or, in other words, where the fine muddy particles commence to make up a considerable portion of the deposits.’’ 1 It is developed principally in the interior of shells, but its mode of formation is obscure. Murray and Renard argue that after the death of the organism the shell first becomes filled with fine mud, upon which, in presence of the sulphates of sea water, the organic matter of the animal may act. The iron of the mud is re- duced to sulphide, which afterwards oxidizes to ferric hydroxide, alumina being at the same time removed in solution and colloidal silica set free. The latter, reacting upon the hydroxide, in presence of potassium salts derived from adjacent minerals, finally generates 1 Murray and Renard, Challenger Rept., Deep-sea deposits, 1891, p. 383. 136 THE DATA OF GEOCHEMISTRY. glauconite. This theory is supported by the observation that the glauconitic shells are always associated with the detritus of terrigenous rocks, containing orthoclase, muscovite, and other minerals from which the necessary potassium could be obtained. In a later portion of this work we shall have to examine the subject of glauconite more fully. An elaborate discussion of it would be out of place now. Oceanic deposits, then, whether of shell, coral, red clay, manganese nodules, or glauconite, are in a sense the fossil records of chemical reactions which have taken place in the depths of the sea. They represent both additions to and withdrawals of matter from the waters of the ocean, with the formation of new substances by chemical change. 1 * The relative quantities of the chemical sediments thus annually formed can be approximately estimated. For this purpose we may first compare in detail the actual amount of each radicle poured into the ocean in one year with the total accumulation of saline matter in the ocean itself. The data are given in the following table: Comparison of oceanic and Jluviatile salts. A. The annual addition of each radicle, by rivers, computed from the data already given in the preced- ing chapter. B. The saline matter in the ocean, computed from Dittmar’s analyses, with Karstens’s value for the volume of the ocean, 1,285,935,211 cubic kilometers, and a mean density of 1.026. A B Annual from rivers In ocean (metric tonsXlO 3 ). (metric tonsXlO 12 ). co 3 961, 350 332, 030 155, 350 95. 6 so 4 3, 553. 0 25, 538. 0 86.8 Cl Br no 3 24, 614 258, 357 57, 982 557, 670 93, 264 75, 213 319, 170 Na 14, 130. 0 510. 8 K Ca 552. 8 Mg 1, 721. 0 Si0 2 Sum 2, 735, 000 X10 3 46, 188.0X10 12 If from each of the quantities in column A we subtract the amount annually retained in solution by the sea, the difference will represent the amount precipitated. To do this, an assumption must be made as to the age of the ocean; but whatever figure is assumed, the results will be of the same order of magnitude. For example, the ocean contains 552.8 X 10 12 metric tons of dissolved calcium; which quan- tity, divided by the assumed age, gives the annual increment. If 1 E. J. Jones (Jour. Asiatic Soc. Bengal, vol. 56, pt. 2, 1887, p. 209) has described another class of marine nodules. They were dredged up in 675 fathoms of water off Colombo, Ceylon, and contained about 75 per cent of barium sulphate. THE OCEAN. 137 the age of the ocean is 100,000,000 years, the annual addition of calcium has been 5,528,000 tons; if only 50,000,000 years it is 11.056.000 tons. Subtracting these quantities from the total cal- cium of the river waters the remainders become 552,142,000 and 546.614.000 tons, respectively; the difference being less than the actual uncertainties of the computation. Calculating upon both assumptions the annual precipitation of chemical sediments is as follows, in metric tons : Age of ocean (years) 100,000,000 50,000,000 so 4 296, 500, 000 552, 142, 000 76, 054, 000 52, 874, 000 75, 213, 000 319, 170, 000 260, 970, 000 546, 614, 000 58, 844, 000 47, 766, 000 75, 213, 000 319, 170, 000 Ca Mg K. Si0 2 If we assume that all the calcium and magnesium are precipitated as carbonates and the sesquioxides as hydrates, the total amount of chemical sediments annually deposited, including coral reefs and calcareous oozes, is somewhere between 2,200,000,000 and 2,400,000,000 metric tons. A little lime undoubtedly goes down as sulphate, although gypsum or anhydrite is found in oceanic sedi- ments only in very small proportions. Probably much of the sulphuric radicle is reduced by organic matter, forming sulphides. The potassium is partly taken up by the clay substances of oceanic silt and partly goes to form glauconite, but there are no data from which to determine its actual distribution. Silica is assumed to be wholly thrown down, the trifling residue held in solution being negligible. Chlorine and sodium are held to remain dissolved. The figures given above for the quantities of the chemical pre- cipitates are, of course, by no means accurate. They are merely rough approximations to the truth, but they tell something of the relative magnitudes. Even if we knew precisely the age of the ocean it would not be practicable to reckon backward and so to determine the total mass of deposits formed during geological time. The figures tell us what is happening to-day, but are inapplicable to the past. The reason for this statement is, that apparently the different deposits have formed at different rates. In the beginning of chemical erosion fresh rocks were attacked, and relatively more silica and less lime passed into solution. At present, limestones laid down in pre- vious geologic ages are being dissolved, and calcium is added to the ocean more rapidly than in pre-Cambrian time. This is not mere speculation. A study of river waters with reference to their origin, whether from crystalline or sedimentary rocks, fully justifies my assertions. 138 THE DATA OF GEOCHEMISTRY. So much for the annual precipitation. J. Joly, * 1 by a different method, has calculated that the total mass of chemical sediments in the ocean is about 19.5 XlO 16 metric tons. This estimate is not inconsistent with the foregoing computations. Purely mechanical sediments, such as river silt, volcanic ejectamenta, or dust brought by the atmosphere from the land, are obviously left out of considera- tion here. Their sum total could hardly be estimated, at least not with existing data. 2 POTASSIUM AND SULPHATES. In seeking to balance the gains and losses of the ocean some account must be taken of potassium and of sulphates. The latter have already been mentioned as partly reduced by organic matter, a change which is counterbalanced to some extent by reoxidation under other circumstances. On the whole, sulphates seem to accu- mulate in the ocean, but the figures are not wholly concordant or satisfactory. The extent of their precipitation is by no means clear, although they are found in all the clays and oozes in trivial propor- tions. With potassium other conditions hold, and river and ocean water are not at all alike. In river waters, on an average, the proportion of potassium is about one-fourth that of the sodium; 3 but in sea water it is only one-thirtieth. In the igneous rocks sodium and potassium are nearly equal; they pass unequally into the streams, and in the ocean the difference is still further increased. What becomes of the potassium ? The answer to this question is simple. Hydrous silicates of alumi- num, the clays, are able to take up considerable proportions of potassium and to remove its salts from solutions. According to J. M. van Bemmelen, 4 ordinary soils will extract more potassium than sodium from solutions in which the salts of both metals are present, even where the sodium is in excess. Potassium, then, is removed from natural waters as they percolate through the soil, or else by the suspended silt carried by streams. The sodium is not so largely with- drawn, and therefore its relative proportion tends steadily to increase. One metal is deposited with the sediments, the other remains in solution. 1 Radioactivity and geology, pp. 57, 58. 1 In an interesting but not altogether conclusive paper (Jour. Geology, vol. 2, 1894, p. 318) J. A. Udden has endeavored to show that the dust carried by the atmosphere is of greater amount than the silt trans- ported by rivers. See also E. E. Free, Science, vol. 29, 1909, p. 423. In Bull. Bur. Soils No. 68, U. S. Dept. Agr., 1911, Free gives an elaborate discussion of the movement of the soil by wind, and a full bibliography of the subject. a Many of the analyses of river water, as published, show no potassium, but this only means that they are incomplete. In such cases the alkalies were weighed together and in calculation the potassium was ignored. This is especially true of boiler-water analyses. * Landw. Versuchs-Stationen (Berlin), vol. 21, 1877, p. 135. The adsorption of potassium has been estab- lished by the work of many investigators. THE OCEAN. 139 These observations are confirmed in part by analyses of oceanic deposits, although the evidence is often incomplete. The larger number of analyses given for clay, mud, and ooze in the Challenger report contain no mention of alkalies, but when the latter are noted the potassium is commonly, not always, in excess. 1 In glauconite and phillipsite deposits potassium always predominates. L. Schmelck, 2 in his analyses of clays from the northern Atlantic, records no alkalies, but K. Natterer, 3 in sediments from the eastern Mediterranean and the Red Sea, found small quantities of potash and soda, and in nearly every instance potash was the more abundant of the two. In short, if the recorded analyses are correct, the clays and oozes of the deep sea have been partly leached of their alkalies; but some of the potassium from the original volcanic material, with less sodium, has been retained in the production of zeolites. Nearer to land potassium has been used in the formation of glauconite, and still nearer, where mechanical sediments appear, a similar discrimination is evident. Sodium dissolves, but potassium is held back. Potassium salts are also absorbed by some seaweeds in large quantities. This has been recently shown by D. M. Balch, 4 who finds that the giant algse of the California coast are remarkably rich in potassium chloride. THE CHLORINE OF SEA WATER. It is not possible at present to trace all of the changes which take place in ocean water, nor to account with certainty for the difference between sea salts and the material received from streams. In chem- ical character, fresh and salt water are opposites, as a brief inspection of the data will show. In ocean water, C1>S0 4 >C0 3 ; in average river water, C0 3 >S0 4 >C1. So also for the bases — in the first case, Na >Mg >Ca; in the other, Ca >Mg >Na — a complete reversal of the order. We can understand the accumulation of sodium in the ocean, and some of the losses are accounted for, but the great excess of chlorine in sea water is not easily explained. In average river water sodium is largely in excess of chlorine; in the ocean the opposite is true, and we can not well avoid asking whence the halogen element was derived. Here we enter the field of speculation, and the evi- dence upon which we can base an opinion is scanty indeed. 5 To the advocates of the nebular hypothesis the problem is compara- tively simple. If our globe was formed by cooling from an incan- 1 This conclusion is confirmed by a recent and very complete analysis of the “red clay,” conducted in the laboratory of the United States Geological Survey. These sediments will be considered more fully in another chapter. 2 Den Norske Nordhavs-Expedition, pt. 9, 1882, p. 35. s Monatsh. Chemie, vol. 14, 1893, p. 624; vol. 15, 1894, p. 530; vol. 20, 1899, p. 1. * Jour. Indust, and Eng. Chem., vol. 1, 1909, p. 777. 5 On the ratio between sodium and chlorine in the salts carried by rivers to the sea, see E. Dubois, Proc. Sec. Sci., Amsterdam Acad., vol. 4, 1902, p. 388. On the ratio between Cl and SO* in sea water, see E. Rup- pin, Zeitschr. anorg. Chemie, vol. 69, 1910, p. 232. 140 THE DATA OF GEOCHEMISTRY. descent mass, its primitive atmosphere and ocean must have been quite unlike the present envelopes, and we may fairly suppose that they contained large quantities of acid substances. Hydrochloric acid in the atmosphere would imply a solution of hydrochloric acid in the sea, which might in time be neutralized by the bases dissolved from rocks and poured by rivers into the common reservoir. This argument has been especially developed by T. Sterry Hunt , 1 who shows that, if his premises are sound, the primeval ocean must have been much richer in calcium and magnesium than the sea is to-day. The richness of some artesian waters of Canada in lime salts, waters which Hunt regards as fossil remainders from the early sea, may be cited in support of his views. On the other hand, R. A. Daly 2 has cited paleontological data in favor of the view that the pre-Cambrian ocean was nearly free from lime. The absence of fossils from rocks of an age immediately pre- ceding a period rich in highly developed calcareous forms is taken as evidence that the earliest life was essentially shcll-less and soft- bodied, in consequence of a deficiency of lime salts in its environment. It is possible, however, that the pre-Cambrian animals were developed under conditions which favored the formation of aragonitic rather than calcitic exoskeletons. Aragonitic shells dissolve much more readily than those formed of calcite, and therefore rarely appear as fossils. Another group of writers, seeking to avoid the nebular hypothesis, conceive the earth as having been built up by the slow aggregation of small, solid, and cold meteoric bodies . 3 Each of these, it is supposed, carried with it entangled or occluded atmospheric material. In course of time central heat was developed by pressure, and a partial expulsion of gas followed, thus forming an atmosphere derived from within. When the atmosphere became adequate to retain solar heat, and so to raise the surface temperature of the globe above the freezing point, the hydrosphere came into existence; but of its chemical nature at the beginning nothing, so far as I am aware, has been said by the advocates of this doctrine. There is, however, an analogy which may be utilized. Meteoric iron frequently incloses anhydrous ferrous chloride, or lawrenceite, a fact of which the curators of collections are painfully aware. The ferrous chloride deliquesces, the liquid formed then undergoes oxidation, ferric hydroxide is deposited, and acid solutions are developed which still further attack the iron. 1 Am. Jour. Sei., 2d ser., vol. 39, 1865, p. 176; and various papers in his Chemical and geological essays. See also J. Joly, on the geologic age of the earth, in Trans. Roy. Dublin Soc., 2d ser., vol. 7, 1899, p. 23; and R. A. Taylor, Proc. Manchester Lit. Philos. Soc., vol. 50. 1906, p. ix. 2 Am. Jour. Sci., 4th ser., vol. 23, 1907, p. 93. Also a later paper in Bull. Geol. Soc. America, vol. 20, 1909, p. 153. 3 See T. C. Chamberlin, Jour. Geology, vol. 5, 1897, pp. 653 et seq.; also H. L. Fairchild, Am. Geologist, vol. 23, 1899, p. 94. THE OCEAN. 141 Through this process of corrosion certain meteoric irons have crum- bled into masses of rust and disappeared as specimens from museums. If, now, the earth was formed from meteoric masses, some of them doubtless contained this annoying impurity, and chlorine from that source may have reached the primeval ocean. In fact, A. Daubree 1 found lawrenceite in the terrestrial native iron from Ovifak. The planetesimal hypothesis is evidently not inconsistent with the excess of oceanic chlorine. It is also in harmony with the idea advanced by E. Suess, 2 that the ocean has received large accessions from volcanic sources. Hydrochloric acid and volatile chlorides exist in volcanic emanations and must, to some extent, reach the sea. G. F. Becker has recently 3 discussed this phase of the problem and has shown that a comparatively moderate emission of volcanic chlorine would fully account for the excess of that element in the ocean. But if, as has often been suggested, the volcanic gases were first derived from oceanic infiltrations, they represent no gain to the ocean, and this question is still at issue. THE DISSOLVED GASES. Up to this point we have considered only the saline matter of the ocean; but the dissolved gases are almost equally important and have been the subject of exhaustive investigations. The earlier researches were not altogether satisfactory, and we need therefore examine only the more recent data, first as to the air and then as to the carbonic acid of sea water. The solubility of a gas in water varies with its nature and with the temperature, being greatest in the cold and diminishing as the sol- vent becomes warmer. The Arctic Ocean, therefore, dissolves more air than the waters of tropical regions, and it also seems to carry a greater proportion of oxygen. We have already seen, in studying the atmosphere, that water exercises a selective function in the solu- tion of air, so that the dissolved gaseous mixture is enriched in oxy- gen. Ordinary air contains by volume only about one part in five of oxygen; dissolved air contains, roughly, one part in three; although, as we shall see, the proportion changes as conditions vary.. Even the salinity of the ocean must probably be taken into account, for the reason that some if not all gases are less soluble in salt than in fresh water. According to the experiments by F. Clowes and J. W. H. Biggs, 4 salt water dissolves only 82.9 per cent as much oxygen as is absorbed by fresh water. So large a difference can not well be ignored. 1 Etudes synth4tiques de g4ologie experiment ale, 1879, p. 557. 2 Geog. Jour., vol. 20, 1902, p. 520. See also C. Doelter, Sitzungsb. Akad. Wien, vol. 112, 1903, p. 704. 3 Smithsonian Misc. Coll., vol. 56, No. 6, 1910. 4 Jour. Soc. Chem. Ind., vol. 23, 1904, p. 358. 142 THE DATA OF GEOCHEMISTRY. To illustrate the difference in solubility between the two principal atmospheric gases, we may use the data given by O. Pettersson and K. Sonden. 1 In pure water the gases dissolve unequally, and the fol- lowing table shows their solubility throughout a fair range of atmos- pheric temperatures. The figures represent the number of cubic cen- timeters of each gas, at 760 millimeters pressure, required to saturate 1 liter of water; and the last column gives the percentage of oxygen in the dissolved mixture, when N + 0 = 100. Solubility of nitrogen and oxygen in water at various temperatures. Tempera- ture. Nitrogen absorbed. Oxygen absorbed. Percentage of oxygen. °C. CTO 3 . CTO®. 0 19. 53 10. 01 33. 88 6. 00 16. 34 8. 28 33. 60 6. 32 16. 60 8. 39 33. 55 9. 18 15. 58 7. 90 33. 60 13. 70 14. 16 7. 14 33. 51 14. 10 14. 16 7. 05 33. 24 When we recall the fact that ordinary air contains only 21 per cent of oxygen, the magnitude of the change produced by solution becomes manifest. In sea water the same relation holds approximately, but the enrich- ment is slightly greater. H. Tomoe, 2 assisted by S. Svendsen, made 94 analyses of air extracted from the water of the North Atlantic and found the oxygen in the mixture N + O to range from a minimum of 31 to a maximum of 36.7 per cent. Between 70° and 80° lati- tude the average was 35.64 per cent; below 70° it was 34.96. At the surface the mean percentage of oxygen was 35.3, and it diminished with the depth from which the samples were taken down to 300 fathoms, when the proportion was reduced to 32.5. Below 300 fathoms the percentage of oxygen was nearly constant. O. Jacobsen, 3 analyzing dissolved air from the water of the North Sea, obtained a range of 25.20 to 34.46 per cent, the surface average being 33.95. Still more elaborate are the data published by W. Dittmar, 4 whose samples of dissolved air came from many points in the Atlantic, Pacific, Indian, and Antarctic oceans. The maximum amount was found in the Antarctic — 28.58 cubic centimeters of air to the liter of 1 Ber. Deutsch. chem. Gesell., vol. 22, 1889, p. 1489. See also R. W. Bunsen, Gasometrische Methoden; W. Dittmar, in his Challenger report; and A. Hamberg, Bihang K. Svensk. Vet.-Akad. Handl., vol. 10, No. 13, 1884. 2 Den Norske Nordhavs-Expedition, Chemistry, 1880, pp. 1-23. Tomoe in this memoir gives a good summary of the earlier investigations. 2 Die Ergebnisse der Untersuchungsfahrten S. M. Knbt. Drache, Berlin, 1886. An earlier memoir by Jacobsen is printed in Liebig's Annalen, vol. 167, 1873, pp. 1 et seq. * Challenger Kept., Physics and chemistry, vol. 1, 1884. For the table cited below, see p. 224. Also for a summary of the results obtained, see the “ Narrative” of the expedition. THE OCEAN. 143 water, containing 35.01 per cent of oxygen. The minimum, 13.73 cubic centimeters and 33.11 per cent, was obtained at a point south- east of the Philippine Islands. The general conclusions as to the solubility of nitrogen and oxygen in sea water at different tempera- tures appear in the table following. Solubility of nitrogen and oxygen in sea water at various temperatures. Temperature. Dissolved nitrogen.® Dissolved oxygen.® Percentage of oxygen. °C. cm. 3 cm. 3 0 15. 60 8. 18 34. 40 5 13. 86 7. 22 34. 24 10 12. 47 6.45 34. 09 15 11. 34 5. 83 33. 93 20 10. 41 5. 31 33. 78 25 9. 62 4. 87 33. 62 30 8. 94 4. 50 33. 47 35 8. 36 4. 17 33. 31 a Supposed to be measured dry, at 0° C. and 760 millimeters pressure; in other words, the normal volumes in cubic centimeters in 1 liter of sea water at the given temperatures. The “nitrogen” of course includes argon. No argument is needed to show the importance of the facts thus developed. The dissolved oxygen plays a double part in the activities of the ocean — first in maintaining the life of marine organisms, and second in oxidizing dead matter of organic origin. By the latter process carbon dioxide is generated, and that compound, as we have already seen, helps to hold calcium carbonate in solution. Its other function as a possible regulator of climate will be considered presently. Free or half-combined 1 carbonic acid is received by the ocean from various sources. It may be absorbed directly from the atmosphere or brought down in rain; it enters the sea dissolved in river water; it is derived from decaying organic matter, and submarine volcanic springs contribute a part of the supply. The free gas is also liberated from bicarbonates by the action of coral and shell building animals, which assimilate the normal calcium salt. Carbonic acid is continu- ally added to the ocean and continually lost, either to the atmosphere again or in the maintenance of marine plants, and we can not say how nearly the balance between accretions and losses may be preserved. The equilibrium is probably far from perfect; it may be disturbed by changes in temperature or by the agitation of waves, and every varia- tion in it leads to important consequences. It is estimated that the ocean contains from eighteen to twenty-seven times as much carbon dioxide as the atmosphere, and that it is therefore, as T. Schloesing 2 has pointed out, the great regulative reservoir of the gas. 1 A much used but inexact expression. It describes tbe second molecule of carbonic acid which converts the normal salts into bicarbonates. * Compt. Rend., vol. 90, 1880, p. 1410. See also A. Krogh, Meddelelser om Groenland, vol. 26, 1904, pp. 333, 409. 144 THE DATA OF GEOCHEMISTRY. Nearly all of the authorities thus far quoted with reference to the dissolved air of sea water have also studied the omnipresent carbonic acid. Jacobsen, Hamberg, Tomoe, Buchanan, Dittmar, Natterer, and others have made numerous determinations of its amount, and as a general rule the quantities found were insufficient to transform all of the normal calcium carbonate into the acid salt. Tornoe, as the aver- age of 78 sea-water analyses, found 52.78 milligrams to the liter of fully combined carbon dioxide, and in addition 43.64 milligrams avail- able for the formation of bicarbonates. Results of the same order were obtained by Natterer in his examination of waters from the Mediterranean. Normal carbonate and bicarbonate are both present in sea water, although in a few exceptional determinations during the Challenger expedition the carbonic acid was clearly in excess. Such instances, however, are rare, and are ascribable to purely local and unusual conditions. The carbonic-acid determinations of the Challenger voyage were conducted partly by J. Y. Buchanan on shipboard, and partly by W. Dittmar on land. 1 The combined acid has already been accounted for in the analyses given for sea salts; the “ loose,” free, or half-com- bined acid, is more variable. Its average amount, in milligrams to the liter, at different temperatures appears in the following table: Average amount of free carbonic acid in sea water at various temperatures. 25° to 28.7°C 20° to 25°C. . 15° to 20°C . . [Milligrams per liter.] 35. 88 37. 18 42. 68 10° to 15°C 5° to 10°C -1.4° to +3.2°C 43. 50 47. 21 53. 31 That is, the ocean contains less free carbonic acid in warm than in cold latitudes. Its average quantity is estimated by Murray at 45 milligrams per liter, which is equivalent to a layer of carbon 3.45 centimeters thick over the entire oceanic area. For different depths of water the variations in carbonic acid are less pronounced, as may be seen from the subjoined averages: Average amount of free carbonic acid in sea water at various depths. Surface 25 fathoms. . 50 fathoms.. 100 fathoms 200 fathoms [ Milli grams per liter.] 42.6 33.7 48.8 43.6 44. 6 300 fathoms 400 fathoms 800 fathoms More than 800 fathoms Bottom 44. 0 41. 1 42.2 44.6 47.4 The figures are derived from 195 determinations by Buchanan, and the individual numbers range from 19.3 to 96 milligrams to the liter. i See vol. 1 of the report on physics and chemistry and part 2 of the “Narrative,” p. 979; also J. Y. Buchanan, in Proc. Roy. Soc., vol. 22, 1874, pp. 192, 483. The tables cited are from the “Narrative.” THE OCEAN. 145 In 15 determinations the carbonic acid was in excess of the amount necessary to form bicarbonates; in only 22 was it sufficient to fully convert the normal into the acid salt. In the light of the evidence just presented, and speaking from the point of view of the modern theory of solutions, we may say that the water of the ocean contains not only the normal carbonic ions, C0 3 , but also a considerable proportion of the bicarbonic ions HC0 3 . The latter ions are unstable, and their existence is conditional on temperature, so that although they are continually forming they are as continually being decomposed. That is, between the ocean and the atmosphere there is an interchange of carbonic acid, which is released from the water in warm climates and absorbed again in the cold. The atmospheric supply of carbon dioxide is thus alternately enriched and impoverished, and the conditions affecting equilibrium are of several kinds. This problem has been elaborately discussed by C. F. Tolman, jr., 1 from the standpoint of the physical chemist, and his memoir should be consulted for the detailed argument. The essential features of the evidence upon which a theoretical discussion can be based are already before us. We have considered the oceanic losses and gains of carbon dioxide, and it remains to correlate them with the corresponding changes in the atmosphere. This can not be done quantitatively, for the rates of consumption and supply are not measurable. In particular, the carbon dioxide from volcanoes and volcanic springs is not a determinable quantity. That the surface of the earth has been subjected to climatic alterna- tions, to glacial periods and epochs of greater warmth, is a common- place of geology. To account for such changes, various astronomical and physical theories have been proposed, and with these, of course, chemistry has nothing to do. Whether, for example, the solar con- stant of radiation is really a constant or not is a question which the chemist can not attempt to answer. The chemical portion of the problem is all that concerns us now; and that relates to the variable carbonation of the atmosphere. The researches of Arrhenius on the possible climatic significance of carbon dioxide were cited and criticized in a previous chapter, and we then saw that its variation in the atmosphere might be attributed to fluctuating volcanic activity. A varying supply of the gas was postulated, and its influence on atmospheric temperatures was shown to offer a plausible, but not well-sustained, explanation of alternating climates. A variable consumption of carbon dioxide would obviously produce much the same effect, and it is therefore evident that supply i Jour. Geology, vol. 7, 1899, p. 585. See also memoirs by C. J. J. Fox, Trans. Faraday Soc., vol. 5, 1909, p. 68; J. Stieglitz, Pub. 107, Carnegie Inst, of Washington, 1909, p. 235; E. Ruppin, Zeitschr. anorg. Chemie, vol. 66, 1910, p. 122. Ruppin discusses especially the alkalinity of sea water. 97270°— Bull. 616—16 10 146 THE DATA OF GEOCHEMISTRY. and loss must be considered together. Disregarding for the moment the doubtful Validity of Arrhenius’s hypothesis, we may consider the interesting work of T. C. Chamberlin , 1 who has sought to show that the ocean is the prime agent in producing the observed changes. The supplies of carbon dioxide are drawn from the storehouse of the ocean, they are consumed in the decomposition of silicates on land, and they are regenerated by the action of lime-secreting animals, which set carbonic acid free, as well as by changes in temperature. According to Chamberlin, an important factor in climatic varia- tion is the fluctuating elevation of the land. During periods of maximum elevation, when the largest land surfaces are exposed to atmospheric action, the consumption of carbon dioxide in rock weathering is great and the air becomes impoverished. When depres- sion occurs and the oceanic area enlarges, a smaller quantity of sili- cates is decomposed and less carbonic acid disappears. The first change is thought to produce a lowering of temperature, which is increased by the consequent greater absorbability of carbon dioxide in sea water; the second causes a relative rise, intensified by a release of the gas from solution. Enlargement of land area implies a low tem- perature, whereas a decrease is conducive to warmth, both conditions hinging on the variability produced in the atmospheric supply of car- bonic acid and its effectiveness as a retainer of solar radiations. But this is not all of the story. A depression of the land is ac- companied by an increased area of shoal water in which lime- secreting organisms can flourish, and they liberate carbon dioxide from bicarbonates. A period of limestone formation is therefore correlated with an enrichment of the atmosphere, and consequently with the maintenance of a mild climate. The ocean is the great reservoir of carbonic acid, and upon its exchanges with the atmos- phere the variations of climate are supposed partly to depend. This argument does not exclude consideration of the volcanic side of the problem, but the oceanic factor seems to be the larger of the two. Chamberlin’s theory is ingenious, but may perhaps carry more weight if stated in somewhat different form. C. G. Abbot and F. E. Fowle , 2 who have studied the influence of the atmosphere upon solar radiations with great care, show that in the lower regions of the atmos- phere water vapor is present in such quantities as almost completely to extinguish the radiation from the earth irrespective of the presence of carbon dioxide. They therefore say that “it does not appear possible that the presence or absence or increase or decrease of the carbonic acid contents of the air are likely to appreciably influence the temperature of the earth’s surface.” i Jour. Geology, vol. 5, 1897, p. 653; vol. 6, 1898, pp. 459, 609; vol. 7, 1899, pp. 545, 667, 751. Chamberlin’s views are criticized by A. Krogh in Meddelelser om Greenland, vol. 26, 1904, pp. 333, 409. * Annals Astrephys. Observ., vol. 2, 1908, pp. 172, 175. THE OCEAN. 147 Water vapor, then, is the chief agent in the atmospheric regulation of climate, and to this conclusion Chamberlin’s theory may be adjusted. When the area of land surface increases, evaporation from the ocean diminishes, and vice versa. The climatic conditions may vary as Chamberlin claims, hut the relative dryness or wetness of the atmosphere may be the true cause of fluctuating temperatures, rather than the carbon dioxide. INFLUENCE OF LIVING ORGANISMS ON THE OCEAN. One other important factor in marine chemistry remains to be considered — namely, the influence of living organisms. These, both plants and animals, are almost incredibly abundant in the ocean , 1 and their vital processes play a great part in its chemical activities. This fact has already been noted on what might be called its inor- ganic side — that is, with reference to the function of marine organ- isms in secreting phosphate and carbonate of lime. Coral reefs and the submarine oozes are made up of animal remains, calcareous or siliceous, and their aggregate amount is something enormous. The living animals, however, do much more than to secrete inor- ganic material. In developing they absorb large quantities of car- bon, hydrogen, nitrogen, and oxygen, the principal constituents of their soft tissues. These elements, in one form of combination or another, are released again by decomposition after the organism dies, and they are also eliminated to a certain extent by the vital processes of the living creatures. Where life is abundant there car- bon dioxide is abundant also, and its activity as a solvent of calcium carbonate is greatest . 2 The relations of the ocean to carbon dioxide can not be completely studied without taking into account both plant and animal life. When marine animals die they may become food for others, the scavengers of the sea, or they may simply decompose. The latter fate, obviously, most often befalls creatures whose soft parts are protected by hard shells. Water, carbon dioxide, and ammoniacal salts are the chief products of decomposition, and ammonium car- bonate, thus formed, acts as a precipitant of calcium compounds . 3 The calcium carbonate thus thrown down is in a finely divided con- dition, and therefore peculiarly available for absorption by coral and shell builders. The ammonium salts also, as shown by Murray and Irvine, are food for the marine flora, and on that some portions of the fauna subsist. 1 The abundance of life in the ocean is admirably stated by W. K. Brooks, in Jour. Geology, vol. 2, 1894, p. 455. Its chemical significance can hardly be exaggerated. 2 See W. L. Carpenter in C. Wyville Thomson’s Depths of the sea, 1874, pp. 502-511. Where CO 2 was abundant in bottom waters, the dredge brought up a good haul of living forms. Where it was deficient, the hauls were poor. 8 See J. Murray and R. Irvine, Proc. Roy. Soc. Edinburgh, vol. 17, 1889, p. 89, 148 THE DATA OF GEOCHEMISTRY. But this is not all. Decomposing organic matter reduces the sulphates of sea water to sulphides, which by reaction with carbonic acid yield sulphureted hydrogen. This process, as shown by Murray and Irvine, 1 is particularly effective in bottom waters in contact with “blue mud,” and by it local changes are produced in the composition of the waters themselves. Bacteria also assist in the process, and according to N. Androussof, 2 this H 2 S fermentation is especially conspicuous in the Black Sea. Some of the hydrogen sulphide passes into the atmosphere and is lost to the ocean; some of it reacts upon the iron silicates of the sea floor, to form pyrite or marcasite; and some is reoxidized to produce sulphates again. From all of these considerations we see that the biochemistry of the ocean is curiously complex, and that its processes are conducted upon an enormous scale. The magnitude of their influence can not be expressed in any quantitative terms, and must long remain an unmeasured factor in marine statistics. In all probability the cir- culation and distribution of carbon in the ocean is as much influ- enced by living beings as by exchanges between the sea and the atmosphere. AGE OF THE OCEAN. The facts that we can estimate, with some approach to exactness, the absolute amount of sodium in the sea, and that it is added in a presumably constant manner without serious losses, have led to va- rious attempts toward using its quantity in geological statistics. 3 The sodium of the ocean seems to furnish a quantitative datum from which we can reason, whereas calcium, magnesium, silica, potassium, etc., are more or less deposited from solution, and so become una- vailable for the discussion of such problems as that of geologic time. Nearly 200 years ago Edmund Halley 4 suggested that the age of the earth might be ascertained by measuring the rate at which rivers delivered salt to the sea. The suggestion was of course fruitless for the time being, because the data needed for such a computation were undetermined, but it was nevertheless pertinent, and it now seems to be approaching realization. For reasons already given, the method proposed for estimating geologic time can as yet be only applied provisionally, the data still being imperfect although rapidly accumulating. The present state of the problem is worth consider- ing now. 1 Trans. Roy. Soc. Edinburgh, vol. 37, 1895, p. 481. See also Challenger Rept., Deep-sea deposits, 1891, p. 254; W. N. Hartley, Proc. Roy. Soc. Edinburgh, vol. 21, 1897, p. 25; and Murray and Irvine, idem, p. 35. 2 Guide des excursions du VII Cong. gdol. internat.. No. 29. 8 See, for example, Chapter I of the present volume, where the relative volumes of the sedimentary rocks are estimated. * Philos. Trans., vol. 29, 1715, p. 296. See an abstract in G. F. Becker’s Age of the earth; Smithsonian Misc. Coll., vol. 56, No. 6, 1910; also in Science, vol. 31, 1910, p. 459. THE OCEAN. 149 The first really serious attempt to measure geologic time by the annual additions of sodium to the ocean seems to have been made by J. Joly 1 in 1899. Joly, with Murray’s figures for rainfall, run-off, and the average composition of river water, combined with Dittmar’s analyses of oceanic salts and an estimate of the mass of the ocean, deduced an uncorrected value for the age of the ocean of 97,600,000 years. The calculation is very simple, and by the following equation: Na in ocean Annual Na in rivers = Age of ocean. Joly’s data, however, were much less satisfactory than the data now at hand, as given in this and the preceding chapter. With them the equation now becomes 14,130X10 12 158,357X10 3 89,222,900; the crude age of the ocean to which certain corrections are yet to be applied. 2 The first of these to be studied tends to increase the quo- tient, others to diminish it. A part of the sodium found in the discharge of rivers is the so- called “ cyclic sodium”; that is, sodium in the form of salt lifted from the sea as spray and blown inland to return again to its source in the drainage from the land. 3 Near the seacoast this cyclic salt is abundant; inland its quantity is small. The table given in Chapter II illustrates the way in which the amount falls off as we recede from the shore, and the isochlors of the New England “ chlorine maps” show the same thing most conclusively. Joly estimates that the cor- rection for cyclic salt may be 10 per cent; but Becker in his paper on the age of the earth has discussed the isochlor evidence mathe- matically, and found that 6 per cent is a more trustworthy value. By Ackroyd the significance of the correction is enormously overesti- mated. Adopting Becker’s figure, and deducting 6 per cent from the total river load of sodium, the remainder becomes 148,846,000 metric 1 Trans. Roy. Dublin Soc., 2d ser., vol. 7, 1899, p. 23, and with later corrections, Rept. British Assoc. Adv. Sci., 1900, p. 369. Criticized by W. Mackie, Trans. Edinburgh Geol. Soc., vol. 8, 1902, p. 240; and O. Fisher, Geol. Mag., 1900, p. 124. See also V. von Lozinski, Mitt. K.-k. geog. Gesell. Wien, vol. 44, 1901, p. 74. He cites a paper by E. von Romer, Kosmos, vol. 25, 1900, p. 1, which I have not seen. Related memoirs are by E. Dubois, Proc. Sec. Sci., Amsterdam Acad., vol. 3, 1901, pp. 43, 116; vol. 4, 1902, p. 388. The presi- dential address of W. J. Sollas (Quart. Jour. Geol. Soc., vol. 65, 1909, p. xli) is mainly devoted to this theme. For more details see F. W. Clarke, Smithsonian Misc. Coll., vol. 56, No. 5, 1910, and G. F. Becker, idem, No. 6. 2 These figures differ from those given in my Preliminary study of chemical denudation. In that I used Dole’s data for American rivers, in which all the alkalies were reckoned as sodium alone. The new compu- tation is based on Palmer’s determinations of potassium, which must be subtracted from the former sum. The latter gave 175,040,000 metric tons Na (+K), as against the 158,357,000 Na now employed. 3 For the quantities of salt thus transported see the table given in Chapter II. For a discussion of the significance of the correction for cyclic sodium, see J. Joly, Geol. Mag., 1901, pp. 344, 504; Chem. News, vol. 83, p. 301; and British Assoc. Report, 1900, p. 369. Also W. Ackroyd, Geol. Mag., 1901, pp. 445, 558; Chem. News, vol. 83, 1901, p. 265; vol. 84, 1901, p. 56. 150 THE DATA OF GEOCHEMISTRY. tons, which, divided into the sodium of the ocean, gives a quotient of 94,712,000 years. Joly’s correction of 10 per cent is very nearly equivalent to the assumption that the entire run-off of the globe, 6,524 cubic miles, according to Murray, carries on an average one part per million of chlorine. The chlorine maps, so far as they have been made, show this figure to be excessive. The foregoing correction for “cyclic salt” is, however, not final. It has already been suggested that the wind-borne salt is only in part restored to the ocean, at least within reasonable time. Some of it is retained by the soil, if not permanently, at least rather tenaciously; and the portion which falls into depressions of the land may remain undisturbed almost indefinitely. In arid regions, like the coasts of Peru, Arabia, and parts of western Africa, a large quantity of cyclic salt must be so retained in hollows or valleys which do not drain into the sea. Torrential rains, which occur at rare intervals, may return a part of it to the ocean but not all. Some writers, Ackrovd 1 for example, have attributed the saline matter of the Dead Sea to an accumulation of wind-borne salt, an assumption which contains elements of truth but is probably extreme. A more definite instance of the sort is furnished by the Sambhar salt lake in northern India, as studied by T. H. Holland and W. A. K. Christie. 2 This lake, situated in an inclosed drainage basin of 2,200 square miles and over 400 miles inland, appears to receive the greater part, if not all of its salt from dust-laden winds which, during the four hot, dry months, sweep over the plains between it and the arm of the sea known as the Rann of Cutch. Analyses of the ah during the dry season showed a quantity of salt so carried which amounted to at least 3,000 metric tons over the Sambhar Lake annually, and 130,000 tons into Rajpu- tana. These quantities are sufficient to account for the accumulated salt of the lake, which the authors were unable to explain in any other way. Examples like this of the Sambhar Lake are of course exceptional. In a rainy region salt dust is quickly dissolved and carried away in the drainage. Only in a dry period can it be transported as dust from its original point of deposition to points much farther inland. It appears, however, that some salt is so withdrawn, at least for an indefinitely long time, from the normal circulation, and should, if it could be estimated, be added to the amount now in the ocean. Such a correction, however, would doubtless be quite trivial, and, there- fore, negligible; and the same remark must apply to all the visible accumulations of rock salt, like those of the Stassfurt region, which were once laid down by the evaporation of sea water. The saline matter of the ocean, if concentrated, would represent a volume of Chem. News, vol. 89, 1904, p. 13. * Records Geol. Survey India, vol. 38, 1909, p. 154. THE OCEAN. 151 over 4,800,000 cubic miles; a quantity compared with which all beds of rock salt become insignificant. But although the visible accumulations of salt are relatively insig- nificant, it is possible that there may be quantities of disseminated salt which are not so. The sedimentary rocks of marine origin must contain, in the aggregate, vast amounts of saline matter, widely dis- tributed, but rarely determined by analysis. These sediments, laid down from the sea, can not have been completely freed from adherent salts, which, insignificant in a single ton of rock, must be quite appre- ciable when cubic miles are considered. The fact that their presence is not shown in ordinary analyses merely means that they were not sought for. Published analyses, whether of rocks or of waters, are rarely complete, especially with regard to those substances which may be said to occur in “traces.” It is perhaps not possible to evaluate the quantity of this dissem- inated salt, and yet a maximum limit may be assigned to it. In Chapter I it was shown that 84 , 300,000 cubic miles 1 of the average igneous rock would yield, upon decomposition, all the sodium of the ocean and the sedimentaries. The volume of the sandstones would be approximately 15 per cent of this quantity, or 12 , 645,000 cubic miles. Assume now that the sandstones, the most porous of rocks, contain an average pore space of 20 per cent, or 2 , 529,000 cubic miles, and that all of it was once filled with sea water, repre- senting 118 , 730 , 000 , 000,000 metric tons of sodium. If all of that sodium were now present in the sandstones, and chemical erosion began at the rate assigned to the rivers, namely, 158 , 357,000 tons of sodium annually, the entire accumulation would be removed in about 750,000 years. This, compared with the crude estimate already reached for geologic time is almost a negligible quantity. The correction for disseminated salt is therefore small, and not likely to exceed 1 per cent. The foregoing calculations, so far as they relate to the age of the ocean, imply the assumption that the rivers have added sodium to the sea at an average uniform rate, slight accelerations being offset by small temporary retardations. For the moment let us consider one phase of this suggested variability. The present rate of discharge has been hastened during modern times by human agency, and that acceleration may be important to take into account. The sewage of cities, the refuse of chemical manufactures, etc., is poured into the ocean, and so disturbs the rate of accumulation of sodium quite perceptibly. The change due to chemical industries, so far as it is measurable, is wholly modern, and that due to human excretions is limited to the time since man first appeared upon the earth. Its 1 This quantity, it must be remembered, is a maximum. The true value is probably very much less, by 10 per cent or even more. 152 THE DATA OF GEOCHEMISTRY. exact magnitude, of course, can not be determined, but its order seems to be measurable, as follows: According to the best estimates, about 14,500,000 metric tons of common salt are annually produced, equivalent to 5,700,000 tons of sodium. If all of that was annually returned to the ocean, it would amount to a correction of about 3.25 per cent on the total addition of sodium to the sea. The fact that much of it came directly or indi- rectly from the ocean in the first place is immaterial to the present discussion; the rate of discharge is affected. All of this sodium, however, is not returned; much of it is permanently fixed in manu- factured articles. The total may be larger, because of other additions, excretory in great part, which can not be estimated, but we may assume, nevertheless, a maximum of 3 per cent as the correction to be applied. Allowing 6 per cent, as already determined, to cyclic or wind-borne sodium, and 1 per cent to disseminated salt of marine origin, the total correction is 10 per cent. This reduces the 158,357,000 tons of river sodium to 142,521,000 tons, and the quo- tient representing crude geologic time becomes 99,143,000 years. The corrections so far considered are all in one direction, and increase, by a roughly evaluated amount, the apparent age of the ocean. Other corrections, whose magnitudes are more uncertain, tend to compensate the former group. The ocean may have con- tained primitive sodium, over and above that since contributed by rivers. It receives some sodium from the decomposition of rocks by marine erosion, which is estimated by Joly as a correction of less than 6 per cent and more than 3 per cent on the value assigned to geologic time. Sodium is also derived from volcanic ejectamenta, from “juvenile” waters, and possibly from submarine rivers and springs. The last possibility has been considered by Sollas, 1 but no numerical correction can be devised for it. These four sources of sodium in the sea may be grouped together as nonfluviatile, and reduce the numera- tor of the fraction which gives the age of the ocean. Whether they exceed, balance, or only in part compensate the other corrections it is impossible to say. From the foregoing computations it is to be inferred that the age of the ocean, since the earth assumed its present form, is somewhat less than 100,000,000 years. If, however, any serious change of rate in the supply of sodium to the sea has taken place during geologic time, the estimate must be correspondingly altered. This side of the question has been studied by G. F. Becker in the memoir already cited, who has shown that the rate was probably greater in early times than now, and has steadily tended to diminish. Wlien erosion began, the waters had fresh rocks to work upon. Now, three-fourths Presidential address. Quart. Jour. Geol. Soc., May, 1909. THE OCEAN. 153 of the land area of the globe are covered by sedimentary rocks or by detrital and alluvial material, from which a large part of the sodium has been leached. The accessible supply of sodium has decreased, and it may be supposed that at some remote time in the future it will be altogether exhausted. From considerations of this order Becker has developed an equation representing the supply of sodium to the ocean during past time by a descending exponential, and has shown that the age of the ocean, as deduced from the data already given, must lie somewhere between 50 and 70 millions of years. The higher figure, he thinks, is closer to the truth than the lower one. If the ocean was initially saline the estimate of its age would be still further reduced. Becker’s conclusions are fairly accordant with the results derived from physical, astronomical, and paleontological evidence, although the study of radioactivity among minerals has led to much higher figures for the age of the earth. The latter line of evidence will be considered in another chapter, but it seems that the rate of chemical erosion offers a more tangible and definite mode of attack upon the problem of geologic time. The problem can not be regarded as definitely solved, however, until all available methods of estimation shall have converged to one common conclusion. 1 1 For persistent criticisms of the chemical method of computing geological time, see H. S. Shelton, Chem. News, vol. 99, 1909, p. 253, vol. 102, 1910, p. 75; vol. 112 , 1915, p. 85; Jour. Geology, vol. 18, 1910, p. 190; Sci. Progress, vol. 9, 1914, p. 55. The criticisms are based upon a belief that the analyses of river waters are inaccurate, especially in the determination of Na and SO 4 ; that is, the skill and accuracy of many reputable chemists are questioned. On this subject, see the rejoinder by R. B. Dole, Chem. News, vol. 103, 1911, p. 289. Mr. Shelton also claims that he has found a discrepancy between the SO 4 determina- tions in waters and the amounts found in igneous rocks. In making this claim he has compared the mean percentage of S in the great mass of igneous rocks with that of the soluble matter leached from a thin film of surficial deposits. The two quantities are not commensurable. CHAPTER V. THE WATERS OF CLOSED BASINS. PRELIMINARY STATEMENT. In dealing with the ocean and its tributary rivers we have studied the hydrosphere in its larger sense, the waters all forming part of one great system of circulation which can be treated as a unit. But on all the continents there are isolated areas from which the drainage never reaches the sea. Streams originate in the higher portions of such areas, resembling in all respects those tributary to the ocean. Their waters gather in depressions and, ultimately, by the concentration of their saline constituents form salt or alkaline lakes or even dry beds of solid residues. The latter condition is developed in small areas of great aridity, where evaporation is so rapid that no large body of water can accumulate; but the more im- portant closed basins are characterized by the formation of permanent reservoirs, such as the Caspian, the Great Salt Lake, and the Dead Sea. Each basin exhibits individual peculiarities of more or less local origin, and therefore each one must be studied separately. No such uniformity as that shown by the ocean is manifested here, although in some lakes we can recognize a curious approximation in chemical character to that of the open sea. THE BONNEVILLE BASIN. To American students the most accessible and therefore the most interesting of these isolated regions is that known as “the Great Basin” in the western part of the United States. This area is fully described in two monographs of the Geological Survey , 1 in which it is represented as having been formerly the seat of two great lakes, Bonneville and Lahontan, of which only the remnants now exist. The Great Salt Lake of Utah is the chief remainder of Lake Bonneville and, with its accessory waters, may well occupy our attention first. The water of Great Salt Lake has been repeatedly analyzed — on the whole with fairly concordant results, except in regard to salinity. The latter varies with changes in the level of the lake, but is always several times greater than that of sea water. An early, incomplete analysis by L. D. Gale and a questionable one by H. Bassett are hardly worth reproducing . 2 The other available data, expressed in percentages of total salts, are as follows : 1 G. K. Gilbert, Lake Bonneville: Mon. U. S. Geol. Survey, vol. 1, 1890. I. C. Russell, The geological history of Lake Lahontan: Mon. U. S. Geol. Survey, vol. 11, 1885. 2 They are cited in Gilbert’s monograph. Bassett’s analysis is very high in potassium. 154 THE WATERS OF CLOSED BASINS. 155 Analyses of water from Great Salt Lake. A. By O. D. Allen, Kept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 433. Water collected in 1869. A trace of boric acid is also reported, in addition to the substances named in the table. Allen also gives analyses of a saline soil from a mud flat near Great Salt Lake. It contained 16.40 per cent of soluble matter much like that of the lake water. B. By Charles Smart. Cited in Resources and attractions of the Territory of Utah, Omaha, 1879. Analysis made in 1877. C. By E. von Cochenhausen, for C. Ochsenius, Zeitschr. Deutsch. geol. Gesell., vol. 34, 1882, p. 359. Sample collected by Ochsenius April 16, 1879. Ochsenius also gives an analysis of the salt manufactured from the water of Great Salt Lake. D. By J. E. Talmage, Science, vol. 14, 1889, p. 445. Collected in 1889. An analysis of a sample taken in 1885 is also given. E. By E. Waller j, School of Mines Quart., vol. 14, 1892, p. 57. A trace of boric acid is also reported. F. By W. Blum. Collected in 1904. Recalculated to 100 per cent. Reported by Talmage in Scottish Geog. Mag., vol. 20, 1904, p. 424. An earlier paper by Talmage on the lake is in the same journal, vol. 17, 1901, p. 617. G. By W. C. Ebaugh and K. W illiams, Chem. Zeitung, vol. 32, 1908, p. 409. Collected in October, 1907. H. By R. K. Bailey, in the laboratory of the U. S. Geological Survey. Sample collected by H. S. Gale, October 24, 1913. A B C D E F G H Cl 55. 99 56. 21 55. 57 56. 54 55. 69 55. 25 55. 11 55. 48 Hr Trace. Trace. Trace. so 4 6. 57 6. 89 6. 86 5. 97 6. 52 6. 73 6. 66 6. 68 co, .07 .09 Li Trace. .01 Trace. Na 33. 15 33. 45 33. 17 33. 39 32. 92 34. 65 32. 97 33. 17 K 1. 60 (?) .20 1. 59 1. 08 1. 70 2. 64 3. 13 1. 66 Ca . 17 .21 .42 1. 05 . 16 . 17 .16 Mg 2. 52 3. 18 2. 60 2. 60 2. 10 .57 1. 96 2. 76 Fe,Oo, AloO,, SiOo .01 Salinity, per cent 100. 00 14. 994 100. 00 13. 790 100. 00 15. 671 100. 00 19. 558 100. 00 °23.036 100. 00 27. 72 100. 00 22. 99 100. 00 20. 349 a More correctly, 230.355 grams per liter. Although the salinity of the lake is very variable and from four to seven times as great as that of the ocean, its saline matter has nearly the same composition. The absence of carbonates, the higher sodium, and the lower magnesium are the most definite variations from the oceanic standard; but the general similarity, the identity of type, is unmistakable. Gilbert estimates the quantity of sodium chloride contained in the lake at about 400 millions and the sulphate at 30 millions of tons. For the waters tributary to Great Salt Lake many analyses are available. 1 The following table relates to some of the streams, except that Sevier Lake, an outlying remnant of Lake Bonneville, is included as a matter of convenience. The analyses are all reduced to standard form, with bicarbonate radicles recalculated to normal C0 3 . Salinity is stated in parts per million. 1 In addition to the data given here, see analyses by J. T. Kingsbury, of City, Red Butte, Farmington, Emigration, Parleys, Big Cottonwood, and Littlo Cottonwood creeks, cited by G. B. Richardson in Water- Supply Paper U. S. Geol. Survey No. 157, 1906, p. 30; analyses made in 1882 and 1884. Field Operations Bur. Soils, U. S. Dept. Agr., 1903, p. 1138, contains analyses of Provo River, Spanish Fork, American Fork and Dry, Payson, Santaquln, Currant, and Warm creeks, but the analyst is not named. Other analyses of Great Salt Lake, complete and partial, are given by W. C. Ebaugh and W. Macfarlane in Science, vol. 32, 1910, p. 568. 156 THE DATA OF GEOCHEMISTRY. Analyses of waters tributary to Great Salt Lake. A. Bear River at Evanston, Wyoming. Analysis By F. W. Clarke, Bull. U. S. Geol. Survey No. 9, 1884, p. 30. B. Bear River at Corinne, Utah, near its mouth. Analysis received from the Southern Pacific Railroad. C. Jordan River at intake of Utah and Salt Lake canal. Analysis by F. K. Cameron, Rept. No. 64, Bur. Soils, U. S. Dept. Agr., 1900, p. 108. D. Jordan River near Salt Lake City. Analysis by Cameron, loc. cit. E. City Creek, Utah. Analysis by T. M. Chatard, Bull. U. S. Geol. Survey No. 9, 1884, p. 29. F. Ogden River at Ogden, U tah. G. Weber River at mouth of canyon. Analyses F and G made under the direction of F. K. Cameron, Field Operations Div. Soils, U. S. Dept. Agr., 1900, p. 226. H. Sevier Lake. Analysis by Oscar Loew, Rept. U. S. Geog. Surveys W. 100th Mer., vol. 3, 1875, p. 114. Sample taken in 1872. A B C D E F G H Cl 2. 68 32. 36 35.54 34. 76 5. 38 23. 21 13. 73 52. 66 so 4 5. 76 8. 16 26. 54 30. 68 2. 87 5. 65 9. 25 10. 88 CO, 52. 68 21.53 2. 67 Trace. 52. 57 33. 68 40. 00 Na 1 4.49 120. 54 126. 13 123.04 1 3. 74 11. 31 8. 37 33. 33 K / / / / / 4. 16 4. 19 Ca 23. 69 10. 12 7.59 10. 26 24. 19 16. 05 18. 19 .12 Mg 6. 86 4. 76 1. 53 1. 26 7. 15 5. 94 6. 27 3. 01 Si0 2 3. 84 3. 69 (A1 Fe)oO, 2. 53 .41 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 185 637 892 1, 090 243 444 455 86, 400 Utah Lake, at the head of Jordan River, has furnished material for a most instructive series of analyses, as follows : Analyses of water from Utah Lake. A. By F. W. Clarke, Bull. U. S. Geol. Survey No. 9, 1884, p. 20. B. By F. K. Cameron, 1899. C. By B. E. Brown, 1903. D. Mean of three analyses by A. Seidell, 1904. Samples taken in May. E. By B. E. Brown, 1904. Collected August 31. For analyses B, C, D, and E, see F. K. Cameron, Jour. Am. Chem. Soc., vol. 27, 1905, p. 113. All are here reduced to terms of normal carbonates. A B c D E Cl 4. 04 35. 48 26. 23 24. 75 26. 87 so 4 42. 68 26. 53 28. 49 28. 25 30. 14 C0 3 19. 88 2. 66 10. 23 12. 35 8. 48 Li .06 Na | 5.81 | 26. 20 19. 28 18. 19 18. 34 K 2. 34 2. 17 1. 75 Ca J 18.24 7. 58 6. 25 5. 90 5. 34 Sr . 15 Mg 6. 08 1. 55 7. 18 6. 18 6. 85 Si0 2 3. 27 2.00 2. 23 Salinity, parts per million 100. 00 306 100.00 892 100. 00 1, 281 100.00 1, 165 100. 00 1, 254 Although the foregoing analyses are, in one respect or another, incomplete, they tell an intelligible story. Bear River at Evanston is a normal river water, which upon evaporation would yield mainly calcium carbonate, and so, too, is City Creek. Bear River, near its THE WATERS OF CLOSED BASINS. 157 mouth, has changed its character almost completely and has evidently taken up large quantities of sodium chloride from the soil. Utah Lake, in the 20 years intervening between the earliest and latest analyses, has undergone a thorough transformation, and its salinity has more than quadrupled. From a fresh water of the sulphate type it has become distinctly saline, and this change is probably a result of irrigation. Its natural supplies of water have been diverted into irrigating ditches, and at the same time salts have been leached out from the soil and washed into the lake. To some extent, these salts have been brought to the surface as a result of cultivation, so much so that considerable areas of land bordering upon the lake have ceased to be available for agriculture. Its outlet, Jordan River, exhibits the same peculiarities. As for Sevier Lake, which is now reduced to a mere pool in consequence of irrigation along its sources, its water resembles that of Great Salt Lake, except that at the time the analysis was made it was only about half as saline. All of the waters tributary to Great Salt Lake, so far as they have been examined, contain notable quantities of carbonates, which are absent from the lake itself. These salts have evidently been precipi- tated from solution, and evidence of this process is found in beds of oolitic sand, composed mainly of calcium carbonate, which exist at various points along the lake shore. 1 The strong brine of the lake seems to be incapable of holding calcium carbonate in solution. THE LAHONTAN BASIN. The Quaternary Lake Lahontan, which once covered an area of 8,400 square miles in northwestern Nevada, is now represented by a number of relatively small, scattered sheets of water and many alkaline or saline beds. Instead of one large basin there are now several basins, and each one is fed by independent sources of fresh water. Each lake, therefore, has its own individual peculiarities, as the various analyses show. Some of the lakes exist only during the humid season, when large areas are covered by a thin layer of water; others are permanent sheets of considerable depth. Our data relate only to the latter, with their sources of supply. In the statement of some analyses precision, in a certain sense, has been sacrificed to uniformity. In strongly alkaline waters the radicle Si0 3 may possibly exist instead of the colloidal Si0 2 . In no case, however, is the silica high enough to cause a serious error in this respect, and a fraction of 1 per cent will cover the uncertainty. A graver criticism might be based upon the representation of all the car- bonates as normal, for bicarbonates are undoubtedly present in some of the waters, which on evaporation deposit trona in large quantities. If, however, we regard the analyses as representing the percentage 1 See analyses by R. W. Woodward, cited in Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 435, Also an analysis by T. M. Chatard, in Bull. U. S. Geol. Survey No. 228, 1904, p. 331, 158 THE DATA OF GEOCHEMISTRY. composition of ignited residues, the suggested objection no longer holds. We can compare our data upon the uniform basis adopted hitherto, and leave the question of bicarbonates for separate con- sideration later. The divergent character of the analyses seems to render some such procedure necessary. It is only by ehminating variables that we can obtain comparable results. In the next table two groups of analyses appear. Lake Tahoe, a typical mountain lake of great purity, empties through Truckee River, which terminates in Winnemucca and Pyramid lakes. These waters are included in the first group. The second comprises Walker River and Walker Lake. The individual analyses, which, except when otherwise stated, are recalculated from the laboratory records of the Survey, are as follows : Analyses of Lahontan waters — I. A. Lake Tahoe, California. Analysis by F. W. Clarke. B. Truckee River, Nevada. Mean of two concordant “boiler-water analyses ” received from the South- ern Pacific Railroad. C. Pyramid Lake, Nevada. Mean of four concordant analyses by Clarke. D. Winnemucca Lake, Nevada. Analysis by Clarke. E. Walker River, Nevada. Analysis by Clarke. F. Walker Lake, Nevada. Mean of two analyses by Clarke. For analyses A, C, D, E, and F, see Bull. U. S. Geol. Survey No. 9, 1884. A B C D E F Cl 3. 18 7.59 41. 04 47. 88 7. 50 23. 77 S0 4 : 7. 47 12. 87 5. 25 3. 76 16. 14 21. 29 co 3 38. 73 33. 30 14. 28 7. 93 30. 34 17. 34 Na 10. 10 1 17. 26 33.84 36. 68 \ 18. 07 \ 34.83 K 4. 56 J 2. 11 1. 94 j } Ca 12. 86 11.02 .25 .55 12. 96 .90 Mg 4. 15 3. 49 2. 28 .49 2. 21 1. 56 Si0 2 (Al,Fe)oO. 18. 95 } 14. 47 .95 .77 12. 78 .31 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million .... 73 153 3, 486 3,602 180 2, 500 The changes shown by these waters 1 are elaborately discussed by Russell in his work on Lake Lahontan. Ordinary fresh waters rich in carbonates and in calcium are concentrated, and the lime salts are finally thrown out in the form of tufa. The tufa, however, instead of being an oolitic or granular deposit, as in the Bonneville basin, is in the form of crystals, “ thinolite,” pseudomorphous after some unknown mineral, which may have been a calcium chlorocarbonate. This peculiar variety of tufa is characteristic of the Lahontan basin; but the mode of its formation is uncertain . 2 1 Except that of analysis B, which is more recent. 2 See discussion by E. S. Dana, in Bull. U. S. Geol. Survey No. 12, 1884. Calcite pseudomorphs, simi- lar to thinolite and called pseudogay lussite, have been discussed by F. J. P. van Calker (Zeitschr. Kryst. Min., vol. 28, 1897, p. 556) and C. O. Trechmann (idem, vol. 35, 1902, p. 283). The Australian glendonite is calcite pseudomorphous after glauberite and sometimes forms crystals 15 to 20 inches long. See T. W. E. David, Rec. Geol. Survey New South Wales, vol. 8, 1905, p. 162. THE WATERS OF CLOSED BASINS. 159 Four more analyses of Lahontan waters remain to be considered, as follows: Analyses of Lahontan waters — II. G. Humboldt River, Nevada. Analysis by T. M. Chatard. H. Humboldt Lake, Nevada. Analysis by O. D. Allen, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 743. I. The large Soda Lake, Ragtown, Nevada. Surface sample. Analysis by Chatard. J. The large Soda Lake, sample from a depth of 30.5 meters. Analysis by Chatard. For these analyses of Chatard’s see Bull. U. S. Geol. Survey No. 9, 1884. An earlier analysis of Soda Lake by O. D. Allen is given in the Fortieth Parallel report, vol. 2, 1877, p. 748. It is less complete than Chatard’s, but other' wise not very different. This water contains bicarbonates. Specific gravity, 1.101. G H I J Cl 2. 19 31. 82 36. 51 35. 38 so 4 13. 92 3. 27 10. 36 10. 50 co 3 39. 55 21. 57 13. 78 15. 89 PO. .07 BXL .25 .26 Na 13. 63 29. 97 36. 63 35. 38 K 2. 92 6.54 2. 01 2. 13 Ca 14. 28 1. 35 My 3. 62 1. 88 .22 .21 Si0 2 9. 51 3. 53 .24 .25 ai 2 o 3 .38 Salinity, parts per million 100. 00 361 100. 00 929 100. 00 113, 700 100. 00 113, 700 The first two of these analyses show the change from river to lake water very clearly. There is a concentration of chlorides and a relative loss in silica, magnesium, and calcium. The water of Soda Lake is more than three times as concentrated as sea water, and of an entirely different type. It has no visible supply of water except from springs near its margin, and at certain times it deposits trona and also gaylussite in notable quantities. Gaylussite is a carbonate of calcium and sodium, but no calcium is shown by Chatard’s analy- ses. It must, therefore, be deposited by the lake about as rapidly as it is received. The tributary springs have not been investigated. The Lahontan waters, then, are distinctly alkaline, whereas the lakes of the Bonneville basin are salt. The cause of the difference must be sought in the sources from which the waters are derived, and one distinction is clear. Great Salt Lake is fed by streams and springs which flow in great part through sedimentary formations. Its saline matter is a concentration of old salts which were laid down long ago. The Lahontan lakes, on the other hand, are supplied with water from areas of igneous rocks, in which rhyolites and andesites are especially abundant and from which the alkalies may be obtained. They represent, therefore, a primary concentration of leached mate- rial, as contrasted with the secondary origin of the Bonneville brine. The difference is easily recognized, but it does not explain all of the phenomena. To account for the large amounts of chlorine in the 160 THE DATA OF GEOCHEMISTRY. waters, particularly in that of Great Salt Lake, is not so easy a matter. So far as I am aware, no plausible solution of the latter problem has yet been suggested. The cosmological speculations, which help us in the case of the ocean, hardly seem to be applicable here. LAKES OF CALIFORNIA. In California there are a number of alkaline lakes having a gen- eral resemblance to those of the Lahontan basin. The following analyses are available, and in them, as usual, bicarbonates, if reported, have been reduced to normal form. Analyses of water from alkaline lakes in California. A. Mono Lake. Analysis by T. M. Chatard, Bull. U. S. Geol. Survey No. 60, 1890, p. 53. Sample taken in 1882. Specific gravity, 1.045. An improbable analysis of Mono Lake water, by Winslow Ander- son, is given in his Mineral springs and health resorts of California, San Francisco, 1892, p. 198. In it the calcium salts predominate over all others. B. Owens River at Charlies Butte. Mean of 36 ten-day composite samples, taken between December 31, 1907, and December 31, 1908. Average analysis by W. Van Winkle and F. M. Eaton, Water-Supply Paper U. S. Geol. Survey No. 237, p. 121. A similar annual average is given for the water at Round Valley farther upstream. C. Owens Lake. Analysis by Chatard, op. cit., p. 58. Specific gravity, 1.062. For an early analysis of Owens Lake see O. Loew, Ann. Rept. Geog. Surveys W. 100th Mer., 1876, p. 190. D. Owens Lake. Analysis by C. H. Stone, cited by W. T. Lee in Water-Supply Paper U. S. Geol. Survey No. 181, 1906, p. 22. Sample taken in August, 1905. E. Owens Lake. Analysis by W. B. Hicks in the laboratory of the U. S. Geological Survey. Specific gravity, 1.0977. An analysis by J. G. Smith is given in Bull. Dept. Agr. No. 61, 1914, p. 80. F. Black Lake, near Benton, Mono County. Analysis by Loew, op. cit., p. 191. G. Tulare Lake in 1889. Analysis by E. W. Hilgard, Appendix to Rept. Univ. California Exper. Sta., 1900. This lake has an outlet during floods, but not at other times. An analysis of water collected in 1880 is also given. H. Borax Lake. Analysis by W. H. Melville, published by G. F. Becker in Mon. U. S. Geol. Survey, vol. 13, 1888, p. 265. In addition to the substances named in the table, the original residue contained 4.5, per cent of organic matter. A B c D E F G H Cl 23. 34 9. 49 25. 67 24. 82 25. 40 7. 68 20. 26 32. 27 Br Trace. .04 I Trace. S0 4 12. 86 15. 53 9. 95 9. 93 9. 89 13. 24 20. 77 .13 co 3 23. 42 29. 84 32. 51 24. 55 22. 70 37. 73 19. 55 22. 47 P0 4 . 11 Trace. .02 b 4 o 7 .32 .48 . 14 1. 89 Trace. 5. 05 NO, .48 .45 Li .03 Trace. Na 37. 93 119. 83 37. 83 38. 09 37. 83 39. 05 35. 79 38. 10 K 1. 85 / 2. 18 1. 62 2. 09 2. 03 2.44 1. 52 Rb, Cs Trace. Ca .04 8. 92 .02 .02 .28 .03 Mg . 10 3. 45 .01 .01 .26 .35 Si0 2 .14 12. 37 .29 .14 .20 .27 .65 .01 A1 2 0 3 Trace. .04 } .04 1 Fe 2 0 3 Trace. .09 .02 l .01 Mn 2 0 3 ) J As 2 0 3 .05 100. 00 100.00 100. 00 100.00 100. 00 100.00 100.00 100.00 Salinity, parts per million 51, 170 339 72, 700 213,700 118, 830 18, 500 4, 910 76, 560 THE WATERS OF CLOSED BASINS. 161 Like Soda Lake, Owens and Mono lakes both yield trona on evapo- ration, and at Owens Lake it has been prepared on a commercial scale. 1 Soda Lake was also utilized at one time for the same purpose. Borax Lake, according to Becker, derives its boron from neighboring hot- springs. It deposits some calcareous sinter. NORTHERN LAKES. The region of alkaline lakes continues northward from Nevada and California, and a number of the waters have been analyzed. The more important analyses are given in the following tables. Those made by W. Van Winkle are recalculated from the figures published in Water-Supply Paper No. 363, 1914, with bicarbonates reduced to normal salts. Analyses of water from northern alkaline lakes. A. Summer Lake, Oregon. Analysis by Van Winkle, who cites two other analyses. Specific gravity, 1.0162 at 15°. B. Ana River, a feeder of Summer Lake. Van Winkle analyst. One other analysis is cited. C. Abert Lake, Oregon. Analysis by T. M. Chatard, U. S. Geol. Survey Bull. No. 60, 1890, p. 55. An earlier analysis by F. W. Taylor is not in accord with this. Specific gravity 1.03117, at 19.8°. D. Abert Lake. Analysis by Van Winkle, who cites other analyses. Sample taken in February, 1912. E. Chewaucan River, the chief feeder of Abert Lake. Van Winkle, analyst. Average of 37 analyses of composite samples of water, taken between August 11, 1911, and August 14, 1912. F. Harney Lake, Oregon. Analysis by G. Steiger in the laboratory of the U. S. Geological Survey. Sample taken August 5, 1902. G. Harney Lake. Van Winkle, analyst. Collected March 10, 1912. Specific gravity, 1.0209. H. Malheur Lake, Oregon. Van Winkle, analyst. An analysis of Silver Lake, in the same general region, is also given and one of Donner and Blitzen River, a feeder of Malheur Lake. A B c D E F G H Cl 18. 27 7. 07 36. 04 36. 23 0. 66 27. 50 30. 40 4. 55 so 4 4. 18 5. 21 1. 90 1. 91 5. 99 7. 67 8. 62 7. 64 co 3 35. 57 32. 73 20. 67 20. 82 28. 79 25. 87 19. 77 44. 63 P0 4 Trace. . 33 b 4 o 7 . 92 Present. Present. 4 w V NOo .02 .13 Trace. .46 . 01 . 50 Na 39. 48 \25. 08 39. 33 38. 78 9. 06 35. 78 39. 43 24. 17 K 1. 59 / 1. 44 1. 69 3. 33 1. 91 1. 50 5. 58 Ca Trace. 3. 15 Trace. 10. 13 None. .03 5. 58 Mg Trace. 2. 83 Trace. 2. 54 . 07 Trace. 4. 13 Si0 2 .62 23. 79 .62 .36 38. 64 ! 28 .14 2. 89 ALO, . 27 . 21 None. . 10 Trace. Fe 2 0 3 Trace. .01 Trace. .40 None. Trace. Trace. 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 16, 633 156 39, 172 29, 564 75 10, 427 22, 383 484 1 See Chatard’s memoir on “natural soda” in Bull. U. S. Geol. Survey No. 60, 1890. The nature of the product will be considered later in the chapter on saline residues. 97270°— Bull. 616—16 11 162 THE DATA OF GEOCHEMISTBY. Analyses of water from northern alkaline lakes — Continued. I. Silvies River, the chief feeder of Malheur Lake. Van Winkle, analyst. Average of 23 analyses of composite samples of water, collected between October 12, 1911, and August 14, 1912. J. Pelican Lake, Oregon. Van Winkle, analyst. K. Bluejoint Lake, Oregon. Van Winkle, analyst. Pelican and Bluejoint Lakes are in the Warner Lake basin. Analyses are also given of Crump, Hart, and Flagstaff Lakes, all in the same group. L. Silver Lake, in Christmas Lake basin, Oregon. Analysis by Van Winkle. M. Soap Lake, Washington. Analysis by George Steiger, U. S. Geol. Survey Bull. No. 113, 1893, p. 113. Another analysis by H. G. Knight is given in the previous editions of this work. N. Moses Lake, Washington. Analysis by H. G. Knight, Ann. Rept. Washington Geol. Survey, vol. 1, 1901, p. 295. O. Omak Lake, Colville Indian Reservation, Washington. Analysis by Steiger in the laboratory of the Survey. Specific gravity, 1.004, at 25°. P. Goodenough Lake, a shallow pond 28 miles north of Clinton, British Columbia. Analysis by F. G. Wait, Ann. Rept. Geol. Survey Canada, new ser., vol. 11, 1898, p. 48 R. Cl... so 4 .. co 3 .. P0 4 .. b 4 o 7 . no 3 -. Na... K. . . Ca Mg... Si0 2 .. AI2O3. Salinity, parts per million 2. 88 7. 35 34. 76 .92 10. 42 2. 45 12. 88 3. 13 25. 13 .08 100. 00 163 7. 97 22. 09 30. 87 .07 Present. .05 29. 25 3. 58 2. 27 2. 62 1. 21 .02 100. 00 1, 983 13. 85 5. 67 38. 68 .05 Present. .02 37. 70 2. 26 .57 .63 .55 .02 100. 00 3, 640 0. 87 2. 43 47. 48 .06 ^16. 36 11.07 6. 59 15. 04 10 100. 00 379 M 13. 28 16. 44 30. 22 J 39. 60 Trace. .04 .42 100. 00 28, 195 3. 88 2. 87 51. 56 19. 86 8. 41 7. 25 5. 06 1. 11 100. 00 2, 966 2. 96 21. 12 36. 75 None. 32. 60 4. 52 .23 1. 82 100. 00 5, 704 7. 64 7. 08 41. 41 .62 Trace. 36. 17 6. 65 .02 .04 .04 .33 100. 00 103, 470 All of these waters contain bicarbonates. Goodenough Lake deposits natron, Na 2 CO 3 .10H 2 O, of which an analysis is given. 1 A few saline lakes situated east of the Kocky Mountains have been studied to some extent. The analyses are as follows: 1 Analyses by J. G. Smith of Summer, Christmas, Fossil, North Alkali, Middle Alkali, and South Alkali Lakes, all in Oregon, are given in Bull. U. S. Dept. Agr., No. 61, 1914, p. 80. THE WATERS OF CLOSED BASINS. 163 Analyses of water from saline lakes east of the Rocky Mountains. A. Wilmington Lake, Wyoming. Analysis by E. E. Slosson, Bull. Wyoming Exper. Sta. No. 49, 1901. B. Big Lake. C. Track Lake. D. Red Lake. These three lakes are known as the Laramie or Union Pacific Lakes of Wyoming. They are usually dry, but in 1888 were filled with water. Analyses by H. Pemberton and G. P. Tucker, Jour. Franklin Inst., vol. 135, 1893, p. 52. E. Lake De Smet, Wyoming. Analysis by W. T. Schaller in the laboratory of the U. S. Geol. Survey. An analysis of its feeder, Shell Creek, was also made. See Water-Supply Paper No. 364, 1914, p. 17. F. Devils Lake, North Dakota. Analysis by H. W. Daudt, Quart. Jour. Univ. North Dakota, vol. 1, 1911, p. 225. Reduced to standard form. Ca, 0.04; Si02, 12.2; R2O3, 4.0 parts per million. G. Old Wives or Chaplin Lake, Saskatchewan, Canada. Analysis by F. J. Alway and R. A. Gortner, Am. Chem. Jour., vol. 37, 1907, p. 3. Recalculated to 100 per cent from the original summation of 98.55. A B C D E F G Cl 10. 78 8. 85 2. 74 3. 06 0. 90 10. 45 4. 98 so 4 16. 62 58. 16 64. 30 64. 57 64. 15 54. 07 61. 86 co 3 32. 75 5. 14 4. 24 1. 54 b 4 o 7 2. 03 1. 14 . 57 ■^4^7 ------------- Na 39. 85 27. 00 30. 20 29. 89 20. 85 25. 88 30. 65 K 1. 27 Trace. Ca .93 .53 .59 1. 10 Trace. Trace. Mg 3. 03 1. 09 1. 32 6. 32 5. 36 .97 Si0 2 .22 } .05 ) Trace. Trace. A1 2 0 3 Trace. Trace. Fe 2 0 3 Salinity, parts per million 100. 00 0 119, 700 100. 00 «52, 600 100. 00 ®77, 300 100. 00 «93, 100 100. 00 6, 708 100. 00 11, 278 100. 00 27, 300 a These figures for salinity of the Laramie Lakes have little or no significance, because the "lakes” vary from dry masses of salts to solutions of varying concentration. For additional information about them see L. C. Ricketts, Ann. Rept. Territorial Geologist Wyoming, 1888, p. 45; and A. R. Schultz, Bull. U. S. Geol. Survey No. 430, p. 570. Five of these lakes are essentially solutions of sodium sulphate, and resemble certain bodies of water on the Russian steppes. 164 THE DATA OF GEOCHEMISTRY, CENTRAL AND SOUTH AMERICA. For the saline waters of Central and South America the chemical data are very scanty. Six analyses, however, may be cited here : Analyses of saline waters from Central and South America. A. Lake Chichen-Kanab (“little sea”), Yucatan. Analysis by J. L. Howe and H. D. Campbell, Am. Jour. Sci., 4th ser., vol. 2, 1896, p. 413. Two samples were analyzed, and that from the middle of the lake is given below. The water deposits gypsum. B. Lake Parinacochas, Peru. Analysis by G. S. Jamieson and H. Bingham, Am. Jour. Sci., ser. 4, vol. 34, p. 12, 1912. C. Lake Huacachima, Peru. Analysis by E. Pozzi-Escot, Bull. Soc.chim., 4th ser., vol. 15, 1914, p. 97. Traces of bromides, iodides, and thiosulphates are also reported. The analysis is obscurely stated, and the recalculation here is therefore somewhat uncertain. D. Lagoon of Tamentica, Chile. See F. J. San Rom&n, Desierto i cordilleras de Atacama, vol. 3, Santiago de Chile, 1902, p. 199. E. Rio Saladillo, Argentina. Analysis by Siewert, reported by A. W. Stelzner, Beitrage zur Geologie und Palaeontologie der argentinischen Republik, 1885. Sample taken at Puente del Monte. The river empties into the Laguna de los Porongos. It is salt during drought, nearly fresh in th e rainy season. Stelz- ner estimates that it carries into the laguna, annually, 584,566,200 kilograms of salts. Stelzner also gives analyses by Doering of the Saladillo between Salta and Jujuy, and of Arroyo Salado in Patagonia. F. Laguna de Epecuen, Argentina. Analysis by M. M. Leguizam<5n, Trabajos Cuarto Cong, cient. Pan- Americano, vol. 4, Santiago, 1910, p. 258. A B c D E F Cl 8. 14 46. 87 11.18 50. 44 56. 74 42. 96 so 4 58. 64 10. 59 16. 95 9.17 4. 82 17. 19 co 3 2.16 29. 33 2. 13 no 3 .40 Trace. 2. 14 P0 4 .05 Trace. b 4 o 7 1. 36 s . 12 Na 11. 99 32. 64 36. 54 35. 35 36.40 37. 72 K .43 3. 83 4. 52 2. 29 Ca 13. 49 1. 18 .01 1. 63 Me 7. 31 .82 .34 .60 .41 Si0 2 .07 . 63 A1 2 0 3 .39 Fe 9 0, .03 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, parts per million 4,446 12, 059 (?) 285, 500 108, 250 285, 000 THE WATERS OF CLOSED BASINS. 165 CASPIAN SEA AND SEA OF ARAL. The greatest of all the closed basins is that of the Caspian Sea, which was formerly connected, through the Black Sea, with the gen- eral oceanic circulation. It is also probable that the Sea of Aral was at some time a part of the same great body of water, and therefore the two sheets are properly to be considered together. Many smaller saline lakes are scattered through the Caspian depression, some of them being recent concentrations from overflows, while others are of much older origin . 1 The Caspian Sea, however, is something more than a segregated remnant of the ocean. Its water is diluted by the influx of the Volga, the Ural, arid other important streams, so that its composition is intermediate between that of a river and that of the open sea. Its salinity is relatively low and very variable. At the north end, near the mouth of the V olga, the water is only brackish ; in the deeper southern portions it is much salter. On the eastern side of the Cas- pian there is a large gulf, the Karaboghaz, into which a current continually flows, through a shallow channel, with no compensating return. This current, it is estimated, carries daily into the gulf 350,000 tons of salt; and therefore the salinity of the Karaboghaz is steadily increasing. Its waters no longer support animal life, and saline deposits are forming upon its bottom. Near its margin gypsum crystals are formed; toward the center of the gulf sodium sulphate is deposited. 2 The latter substance is thrown down only during the winter months, for at summer temperatures the Karabo- ghaz brine is an unsaturated solution. In cold weather it is saturated with respect to sodium sulphate, but not for the chloride, and the latter remains dissolved. 3 The separation of salts by fractional crystallization is thus well exemplified. 1 For analyses of some of these waters, the Bogdo, Indersk, and Stepanova lakes, see Roth, Allgemeine und chemische Geologie, vol. 1, p. 469. Modern and complete analyses are much to he desired; the old ones are unsatisfactory. 2 See S. Kusnetsoff, Zeitschr. prakt. Geologie, 1898, p. 26. 3 See N. S. Kurnakoff, Verhandl. Russ. k. min. Gesell., 2d ser., vol. 38, 1900, p. 26 of the proceedings. For a long paper on the Karaboghaz, also known as the Karabugas or Adschi-darja, see W. Stahl, Natur. Wochenschr., vol. 20, 1905, p. 689. Tin's paper is based on an official Russian report by Spindler and Lebo- dintzeff, published in 1902. For an analysis of water from Lake Durun in Transcaspia see A. Stachmann, Jahresb. Chemie, 1887, p. 2531. 166 THE DATA OF GEOCHEMISTRY. To illustrate the composition of the Caspian and allied waters, a few analyses must suffice. The older data can be found in the works of Bischof and Both. The following examples are fairly typical: Analyses of Caspian and allied waters. A. Caspian Sea. Mean of five analyses by C. Schmidt, Bull. Acad. St. Petersburg, vol. 24, 1878, p. 177. B. Caspian Sea. Analysis by A. LebedintzefE, cited by W. Stahl, Natur. Wochenschr., vol. 20, 1905, p. 689. C. Karaboghaz Gulf. Analysis by Schmidt, loc. cit. D. Karaboghaz Gulf. Analysis by LebedintzefE, cited by Stahl, loc. cit. E . Tinetzky Lake, a residue of concentration from the Caspian. Analysis by Schmidt, loc. cit. F. Sea of Aral. Analysis by Schmidt, cited from Roth, Allgemeine und chemische Geologie, vol. 1, p. 465. Schmidt’s analyses report bicarbonates, which are here reduced to normal salts. I have also consolidated the insignificant quantities of silica, phosphoric acid, and ferric oxide, which were determined separately. G. Sea of Aral. Analysis by Stepanow, cited by S. Sowetow, Ann. Hydjog. und Marit. Meteorolog., 1910, p. 658. Other recent analyses are also mentioned, probably from the monograph by L. Berg on the Sea of Aral, published by the Russian Geographical Society, a work which I have not seen. H. The River Atrek, a western tributary of the Caspian. Mean of two analyses by F. K. Otten, Jahresb. Chemie, 1881, p. 1442. Analyses of the tributary rivers Sumbar and Tschandyr are also given. A B c D E F G H Cl ' 42.04 41. 78 53. 32 50. 26 47. 99 35. 40 35. 63 19. 33 Br . 05 . 05 .06 . 08 . 13 .03 S0 4 23. 99 23. 78 17. 39 15. 57 21. 25 30. 98 31. 27 43. 09 co 3 . 37 . 93 . 13 . 85 . 10 6. 09 Na 1 24. 70 24. 49 11. 51 25. 51 18. 46 22. 62 22. 05 19. 03 K . 54 . 60 1. 83 . 81 . 24 . 54 1. 07 Rb .02 .06 .01 .02 Ca 2. 29 2. 60 . 57 .01 4. 02 4. 48 5. 98 Mg 5.97 5. 77 15. 83 7.07 11. 91 5. 50 5.40 5.40 Si0 9 , PCX, FeoO, .03 . 04 1. 08 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 100.00 Salinity, per cent [ 1.294 1. 267 28. 50 16. 396 28. 90 1.084 1. 067 1. 495 Analyses C and D show that the Karaboghaz varies from time to time, both in composition and in concentration. With the exception of the Atrek and two other small streams, analyses of the rivers which feed the Caspian seem to be wanting ; at least, I have found none recorded. They must have carried large amounts of calcium and of carbonic acid, which have been almost entirely eliminated. The falling off of sulphates and the concentration of magnesium in the more saturated waters is clearly brought out by the table, an order of change which will be considered more fully somewhat later. Both the Caspian Sea and the Sea of Aral differ chemically from the ocean in their higher proportions of calcium, magnesium, and sulphates . 1 i Bergstrasser, In Petermann’s Mittheilungen, 1858, pp. 104-105, has brought together 38 old analyses of salts from the lakes of Astrakhan and the mouth of the V olga. For an analysis of water from Lake Tinaksk, Astrakhan, see N. W. Sokoioff, Jour. Chem. Soc., vol. 100, ii, 1911, p. 502, abstract from Jour. Russian Phys.-Chem. Soc., vol. 43, p. 436. THE WATERS OF CLOSED BASINS. 167 THE DEAD SEA. In the water of the Dead Sea some of the phenomena of saline concentration are exhibited to an extreme degree. Sodium com- pounds have been largely eliminated, and the remaining brine resem- bles in many respects the mother liquor left by ocean water after the extraction of salt. It is rich in magnesium, calcium, and bromine ; the sulphates have been reduced to an insignificant amount, and car- bonates are almost entirely lacking. The original solutions, how- ever, from which the Dead Sea was formed were probably not iden- tical in composition with those which produced the salinity of the ocean, and so the bittern of sea water differs from the brine that we are now considering. The two are similar, but not quite the same. The water of the Dead Sea has been repeatedly analyzed and the older data are reproduced in the works of Bischof and Roth. The best series of analyses is due to A. Terreil , 1 and of his eight, six are given below in reduced form. They represent samples collected from different depths and different parts of the lake, and they show its variable character. Analyses of water from Dead Sea and River Jordan. A . Surface water , north end of lake . Terreil . B. At depth of 20 meters, 5 miles east of Wady Mrabba. Terreil. C. At depth of 42 meters, near Has Mersed. Terreil. D. At depth of 120 meters, 5 miles east of Has Feschkah. Terreil. E. Same locality as D, at depth of 200 meters. Terreil. F. Same locality as B, at depth of 300 meters. Terreil. A B c D E F Cl 65. 81 70. 25 68. 16 67. 66 67. 84 67. 30 Br 2. 37 1. 55 1. 99 1. 98 1. 75 2. 72 S0 4 . 31 . 21 . 22 . 22 .22 . 24 C0 3 Trace. Trace. Trace. Trace. Trace. Trace. Na 11. 65 6. 33 10. 21 10. 20 10. 00 5. 50 K 1. 85 1. 70 1. 00 1. 62 1. 79 1. 68 Ca 4. 73 5. 54 1. 53 1. 51 1. 68 6. 64 Mg 13. 28 14. 42 16. 89 16. 81 16. 72 15. 92 Si0 2 Trace. Trace. Trace. Trace. Trace. Trace. Salinity, per cent 100. 00 19. 215 100. 00 20. 709 100. 00 24. 263 100. 00 24. 573 100. 00 25. 110 100. 00 25. 998 1 Compt. Rend., vol. 62, 1866, p. 1329 Terreil also made an analysis of the water of the River Jordan, but stated it obscurely. In addition to the substances named in the table, Terreil reports traces of hydrogen sulphide, ammonia, alumina, ferric oxide, and organic matter in the water of the Dead Sea. 168 THE DATA OF GEOCHEMISTRY. Analyses of water from Dead Sea and River Jordan — Continued. G. Analysis by J. B. Boussingault, Annales chim. phys., 3d ser., vol. 48, 1856, p. 129. Boussingault cites the earlier analyses of Dead Sea water. H. Analysis by F. A. Genth, Liebig’s Annalen, vol. 110, 1859, p. 240. I. Analysis by Roux, Compt. Rend., vol. 57, 1863, p. 602. J. Analysis by H. Fleck, Jour. Chem. Soc., vol. 42, 1882, p. 24, abstract. Probably surface water. K. Analysis by A. Stutzer and A. Reich, Chem. Zeitung, vol. 31, 1907, p. 845. L. Analysis by A. Friedmann, Chem. Zeitung, vol. 36, p. 147, 1912. Specific gravity 1.1298. Mean of 2 analyses. M. Analysis by H. Fresenius, Zeitschr. angew. Chem., 1912, p. 1991. Specific gravity 1.1555 at 15°. The trace of iodine is 0.000247 gram per kilo, and of iron, 0.0007586 gram. N. The Jordan near Jericho. Analysis by R. Sachsse, Inaug. Diss., Erlangen, 1896. Analyses of several smaller streams are given. Organic matter not included in the following table. An earlier analysis by Anderson is cited in the first edition of this book (Bulletin 330). G H I 1 J K L M N Cl 65. 80 65. 22 65. 43 65. 74 64.49 63.40 65. 86 41.47 Br 1. 37 2. 08 1. 54 1.48 1. 45 1. 69 1. 13 I Trace. S0 4 . 13 .29 .20 .33 .45 .42 .39 7.22 co 3 . 01 Trace. . 02 13. 11 no 3 Trace. Na 11. 22 13. 39 11. 70 11. 60 15. 75 13. 49 13. 73 18. 11 K 3. 70 2. 37 3. 53 3. 40 3. 24 3. 24 2. 36 1.14 NII 4 Trace. Trace. Ca 5. 69 4. 79 5. 60 5. 02 4. 09 5. 74 4. 19 10. 67 Mg 12. 09 11. 85 11. 85 12. 42 10. 53 12.02 12. 32 4.88 Si0 2 1. 95 (Al, Fe) 2 0 3 Trace. Trace. .15 Trace. Trace. Trace. 1.45 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Salinity, per cent 22. 7697 22. 2834 20. 590 21. 977 22. 030 23. 8906 18. 8453 0. 770 From the foregoing analyses we see that the water of the Dead Sea differs widely from all the other waters that we have examined. The composition of its main feeder, the Jordan, is also unusual. When it enters the Dead Sea, its carbonates, and gypsum are precipitated, and its contribution to the lake brine is composed almost entirely of chlorides. The valley of the Jordan and the regions roundabout the. Dead Sea contain many beds of rock salt and gypsum, and the neigh- boring Cretaceous strata are impregnated with the same substances. From these sources the river derives its chlorides and sulphates, and so returns to the lake some products of its former concentration. Hot springs, also, as L. Lartet 1 and others have shown, contribute to the salinity of the waters. To some extent, probably, there is atmospheric transportation of salts from the Mediterranean, and W. Ackroyd 2 regards this as a most important agency, although its influence is probably overestimated. Whatever may have been the origin of the Dead Sea, its water is now essentially a bittern, relatively low in sodium, high in magnesium, and remarkably rich in bromine. The Bull. Soc. g6ol. France, 2d ser., vol. 23, 1866, pp. 719-760. 2 Chem. News, vol. 89, 1904, p. 13. THE WATERS OF CLOSED BASINS. 169 brine from 300 meters depth carries over 7 grams of bromine to the liter, but only a trace of iodine has been detected in it. 1 OTHER RUSSIAN AND ASIATIC LAKES. Mother liquors having a general similarity to the Dead Sea brine are also furnished by the Elton Lake, in southern Russia, and the Red Lake, near Perekop, in the Crimea. Their analyses, recalculated from the figures given by Roth, appear in the next table. The com- position of the Elton water varies with the season of the year, and I have selected an analysis which represents its concentration in August. In spring its tributaries, swollen by melting snow, bring in much sodium chloride and alter its character materially. Analyses of water from several Asiatic lakes are included with these in the table following. Analyses of Russian and Asiatic waters. A. Elton Lake, Russia. Analysis by Erdmann, cited by Roth, Allgemeine und chemische Geologie, vol. 1, p. 469. B. Red Lake, Perekop, Crimea. Analysis by Hasshagen, from Roth, op. cit., p. 471. Roth gives anal- yses of several other Crimean salt lakes. Analyses of four Crimean lakes are given by A. Goebel, M61- chim. phys., vol. 5, 1864, p. 326. C. Lake Van, Armenia. Analysis by E. de Chancourtois, Compt. Rend., vol. 21, 1845, p. 1111. Car- bonates reduced to normal salts. D. Lake Urmi or Urmiah, Persia. Analysis by R. T. Gunther and J. J. Manley, Proc. Roy. Soc., vol. 65, 1899, p. 312. E. Salt Lake near Shiraz, Persia. Analysis by K. Natterer, Monatsh. Chemie, vol. 16, 1895, p. 658. F. Gaukhane Lake, southern Persia. Analysis by A.Heider, published by Natterer, op. cit., p. 673. G. Koko-Nor, Tibet. Analysis by C. Schmidt, Bull. Acad. St. Petersburg, vol. 24, 1878, p. 177. Bicar- bonates reduced to normal salts. Sample taken in autumn, 1872. H. Koko-Nor, Tibet. Analysis by Schmidt, M41. chim. phys., St. Petersburg, vol. 11, 1881, p. 487. Sample taken in the winter of 1880, from under thick ice. For analyses of three saline lakes in Central Asia, see Schmidt, idem, vol. 12, 1887, p. 547. A B c D E F G H Cl 64. 22 66. 82 27. 08 57. 33 58. 17 59. 67 40. 05 41. 69 Br .03 .01 .04 .04 I . 11 S~0 4 6. 82 11. 95 5. 06 3. 48 1. 29 17. 84 16. 30 CO, . 04 20. 71 . 23 5. 55 6. 66 vv 3* * * * * Na 11. 27 19. 32 37. 65 33. 98 35. 51 37. 38 30. 60 28. 64 K .58 1. 19 .78 .29 1. 08 . 81 Rb .04 .04 NH 4 .. . .01 Trace. Ca . 10 2. 01 .32 .46 .82 1. 77 .04 Mg 17. 55 11. 13 .57 2. 53 1. 84 . 83 2. 90 5. 66 Si0 2 . 85 .01 .09 .08 Fe<,Oo Trace. .02 .02 P0 4 .02 .02 Salinity, per cent 100. 00 26. 50 100. 00 30. 01 100. 00 2. 10 100. 00 14. 85 100. 00 7. 77 100. 00 25. 88 100. 00 1. 11 100. 00 1. 30 1 The following references to original authorities on the water of the Dead Sea are worth recording: J. Apjohn, Proc. Roy. Irish Acad., vol. 1, 1841, p. 287; B. Silliman, jr., Am. Jour. Sci., 1st ser., vol. 48, 1845, p. 10; T. J. and W. Herapath, Jour. Chem. Soc., vol. 2, 1849, p. 337; A. F. Boutron-Charlard and O. Henry, Jour, pharm. chim., March, 1852; R. M. Murray, Proc. Glasgow Philos. Soc., vol. 3, 1852, p. 242; J. C. Booth and A. Muckle, Am. Jour. Sci., 2d ser., vol. 19, 1855, p. 149; F. Moldenhauer, Liebig’s Annalen, vol. 97, 1856, p. 357; Schwarzenbach, Mitt, naturforsch. Gesell. Berne, 1870, p. 47. An analysis by J. H. Salisbury (Am. Polytech. Jour., vol. 2, 1853, p. 374) of what purported to be Dead Sea water was evidently of ocean water. The earlier analyses by A. Marcet, Klaproth, Gay-Lussac, and C. G. Gmelin have only historical interest. A recent analysis by Mitchell (Berg- u. hiittenm. Zeitung, 1902, p. 225) is of doubtful value. 170 THE DATA OF GEOCHEMISTRY. The general resemblance of analyses A and B to those of Dead Sea water is evident. Elton Lake, however, contains a notable propor- tion of sulphates, which are entirely wanting in the Crimean water. Lake Van is alkaline, and its saline composition is much like that of Mono Lake in California, except that it is less concentrated. Lake Urmi is of the same type as Great Salt Lake, and the two other Persian waters are similar. The Koko-Nor belongs in the same class with the Caspian and the Sea of Aral, but it contains a much larger proportion of carbonates. In the neighborhood of Minussinsk and Abakansk, government of Yeniseisk, Siberia, there are a number of saline lakes or ponds which have been studied by F. Ludwig . 1 The reduced analyses, arranged in the order of their chlorine, are as follows: Analyses of water from saline lakes of Yeniseisk, Siberia. A. The Kisil-Kul. B. Lake Schunett, water collected in 1899. Another analysis, of a sample collected in 1898, gave similar hut somewhat different results, and showed much greater concentration. This latter sample had a salinity of 25.35 per cent, and its salts contained 0.19 per cent of bromine. C. LakeTagar. D. LakeBeisk. E. Bitter Lake. F. Lake Altai. G. Lake Biljo. This is the largest of the lakes and measures about 60 kilometers in circumference. H. Lake Domoshakovo. A B c D E F G H Cl 48. 28 38. 89 29. 52 22. 79 20. 02 14. 38 9. 91 3. 71 Br Trace. Trace. Trace. Trace. Trace. S0 4 14. 55 32. 19 34. 99 42. 32 43. 83 50. 14 52. 33 63. 62 co 3 .22 .31 1. 55 .61 1. 53 1. 12 6. 22 .08 NO, 1. 07 . 07 Na 34. 01 16. 12 28. 41 31. 32 31. 78 32. 83 21. 83 30. 61 K .35 .33 1. 01 1. 01 1. 38 .52 .87 .59 Ca .69 .44 .27 .07 .15 .05 .43 . 58 Mg 1. 86 11. 67 4. 12 1. 86 1. 28 .90 7. 28 .74 Si0 2 .04 .01 .04 .01 .03 .03 .03 Trace. ALO, .04 .09 .01 Trace. .02 .03 Trace. Fe 9 0, Trace. Trace. .01 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 100.00 100. 00 Salinity, per cent 10. 87 15. 19 2.09 10. 47 5. 90 10. 88 .88 14. 55 The last analysis in this table, that of Lake Domoshakovo, repre- sents essentially a solution of sodium sulphate, with very little else. It is the extreme type of a sulphate water. The other waters upon evaporation, yield mixtures of chlorides and sulphates, sodium being the dominant electropositive radicle. In one analysis only is magne- sium high; in two others it is important. The calcium is insignificant throughout the series. 1 Zeitschr. prakt. Geologie, vol. 11, 1903, p. 401. Ludwig also gives analyses of sediments and saline deposits from these waters. THE WATERS OF CLOSED BASIE'S. 171 A number of other Siberian lakes have been investigated by C. Schmidt, from whose memoirs the subjoined analyses, reduced to standard form, have been selected . 1 Analyses of water from Siberian lakes. A. Issyk-Kul. Mel. phys. chim., St. Petersburg, vol. 11, 1882, p. 623. B. Iletsk salt lake, government of Orenberg. Op. cit., vol. 11, 1882, p. 608. Average. C. Barchatow bitter lake, 300 versts southwest of Barnaul, government of Tomsk. Op. cit., vol. 11, 1882, p. 609. D. Buluktii-Kul or Fish Lake, Kirghiz Steppe. Op. cit., vol. 12, 1883, p. 37. A B C D Cl 15. 64 60. 26 45. 05 37. 96 Br .03 Trace. . 11 .04 S0 4 55. 94 .47 20. 23 27. 39 C0 3 1. 26 .98 P0 4 .02 Na 11. 76 38. 86 28. 01 23. 29 K 1. 85 Trace. .26 .32 Ca .94 .33 5. 28 Mg 12. 50 .08 5. 84 4. 68 Fe Trace. Si0 2 .06 .06 S, sulphide.. .50 Salinity, parts per million 100. 00 3, 574 100. 00 155, 230 100. 00 13, 308 100. 00 11, 458 i In M6m. Acad. St. Petersburg, vol. 20, No. 4, 1873, Schmidt gives analyses of 14 bitter, salt, and fresh lakes on the line from Omsk to Petropavlovsk, and thence to Prasnowskaja. 172 THE DATA OF GEOCHEMISTRY. MISCELLANEOUS LAKES. In the next table I give reduced analyses of several European lakes of widely varying character. They are as follows: Analyses of water from European lakes. A. Lake Laach, Germany. Analysis by G. Bischof, Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 1, 1863, p. 316. This lake occupies the crater of an extinct volcano, and its water is fresh. It is, nevertheless, an alkaline water and yields sodium carbonate on evaporation. B. Palic Lake, Banat, Hungary. Analysis by K. von Hauer, Jahrb. K.-k. geol. Reichsanstalt, vol. 7, 1856, p. 361. Iron, magnesium, and calcium are held in solution as bicarbonates, and are precipitated on boiling. Free carbonic acid and organic matter are also present. C. Illyes or Medve Lake, near Szovata, Hungary. Analysis by B. von Lengyel, Foldt, Kozl., vol. 28, 1898, p. 280. Recently formed by a sinking of the ground. The neighboring country contains salt deposits. D. Lake Ruszanda, Hungary. Analysis by J. Schneider, cited by A. Kaleczinzky, Foldt, Kozl., vol. 28, 1889, p. 284. The data as published show discrepancies which detract from their value. Organic matter omitted. E. Lake Tekir-Ghiol, Roumania. Analysis by Popovici, Saligny, and Georgesco, cited by P. Bujor, Ann. sci. Univ. Jassy, vol. 1, 1901, p. 158. A lake of about 1,140 hectares, situated only 300 to 400 meters from the Black Sea. The published summation of the analysis is not in accord with the individual figures. F. Lacu Sarat, Roumania. Analysis by Carnot, cited by Bujor, op. cit., p. 176. In winter this lake deposits crystallized sodium sulphate, mirabilite, Na2SO4.10H2O. In a memoir entitled “Apergu geolo- gique sur les formations saliferes et les gisements de sel en Roumanie,” Bucharest, 1902, L. Mrazec and W. Teisseyre cite analyses of Lacu Sarat, Lacu Fundata, Lacu Amara, and Lacu Ianca. They also give analyses of Roumanian salt. Cl... Br... S0 4 .. co 3 . no 3 . P0 4 . nh 4 . Na.. K... Ca... Mg.. Fe 2 0 3 Si0 2 . Salinity, parts per million. 4. 99 2.97 50. 97 27. 05 9. 90 2. 77 1. 35 100. 00 218 15. 68 2. 92 41. 02 35. 75 .66 3. 35 . 35 .27 100. 00 2,215 60. 18 Trace. .44 .04 39. 02 .25 .03 Trace. .04 100.00 233, 747 19. 07 22.56 19.22 .52 37.07 . 1.19 .20 .15 Traces. .02 100. 00 6, 276 60. 53 .18 .67 Trace. Trace. Trace. 34. 78 1. 68 .28 1. 84 j * .03 .01 28. 25 37* i 2 .27 31. 75 ”*.*39 2. 16 .02 .04 100. 00 70, 877 100. 00 58, 038 Illyes Lake and the neighboring Black Lake are essentially strong solutions of common salt, formed by the leaching of salt beds. Ac- cording to A. Kaleczinzky, 1 they have warm layers under a fresh- water surface, which owe their increased temperature to the absorp- tion of solar heat and to the fact that brine has a lower specific heat than water. The surface layer of Black Lake has a temperature of 21°; the warm layer below reaches 56°. These lakes, therefore, are accumulators of heat. With the analyses of six more lake waters, the present tabulation must close. They are as follows: 1 Ueber die ungarischen warmen und heissen Kochsalz-Seen, etc., Budapest, 1902. An analysis by Hanko of the Black Lake is given. It is practically identical with that of Illyes Lake; the salinity is 19.53 percent. See also F. Schafarzik, Foldt. Kozl., vol. 38, 1908, p. 437. THE WATERS OF CLOSED BASINS. 173 Analyses of saline lakes in Africa, India, and Australia. A. Natron Lake, near Thebes, Egypt. Analysis by E. Willm, Compt. Rend., vol. 54, 1862, p. 1224. No bromine, iodine, nitrates, or sulphates were detected. B. Salt lake 32 kilometers north of Pretoria, Transvaal. Described by E. Cohen, Min. pet. Mitt., vol. 15, 1895, pp. 1, 194. Analysis, incomplete, by H. Hopmann. This lake or salt pan is about 400 meters in diameter and occupies a funnel-shaped depression in granite. C. The Katwee salt lake, north of Albert Edward Nyanza, central Africa. Analysis by A. Pappe and H. D. Richmond, Jour. Soc. Chem. Ind., vol. 9, 1890, p. 734. D. Sambhar Salt Lake, Rajputana, India. Analysis by W. A. K. Christie, Rec. Geol. Survey India, vol. 38, 1909, p. 167. Traces of NIL, Fe, S, BO 3 , PO 4 , and I were also found. For the origin of the salt in this lake see ante, p. 150. E. Lonar Lake, Berar district, Central Provinces, India. Analysis by T. H. D. La Touche and W. A. K. Christie, Rec. Geol. Survey India, vol. 41, 1912, p. 266. Traces of borates detected. F. Lake Corongamite, Victoria, Australia. Analysis by A. W. Craig and N. T. M. Wilsmore, Fourth Rept. Australasian Assoc. Adv. Sci., 1892, p. 270. A B C D E F Cl 26.00 43.47 36.67 52. 96 .04 5.85 40. 76 59.32 .22 1.65 Br SO* .03 12. 33 1.48 .01 17.63 39.60 .11 .01 Trace. Trace. .40 S C0 3 32.90 31.05 15.17 41.33 10.42 33.46 7.09 Trace. Trace. 2.19 38.86 .09 Trace. .01 Undet. 35.07 .84 .13 2.77 Na K Ca 3.57 3.62 1.50 1.36 Mg (Al, Fe) 2 0 3 SiO 2 .03 Trace. Salinity, parts per million. . . . 100. 00 4, 407 100. 00 211, 400 100. 00 310, 000 100. 00 (?) 100. 00 82, 872 100. 00 46, 039 SUMMARY. With the evidence now before us it is easy to see that the waters of salt and alkaline lakes may be classified in a few fairly well defined groups. First, we have a group of chloride waters, characterized mainly by sodium chloride, which may be regarded as belonging to an oceanic type. In the following table these waters are summed up in the order of diminishing chlorine, only the main constituents being given : Principal constituents of chloride waters. Lake Tekir-Ghiol Iletsk Lake Illyes Lake Gaukhane Lake Lake Corongamite Lake near Shiraz Lake Urmi Rio Saladillo Great Salt Lake (average) Ocean Sambhar Lake Cl, Br. S0 4 . C0 3 . Na, K. Ca. Mg. 60.71 0.67 Trace. 36.46 0. 28 1.84 60.26 .47 38.86 .33 .08 60. 18 .44 0.04 39.02 .25 .03 59.67 1.29 37.38 .82 .83 59. 54 1.65 (?) 35. 91 .13 2. 77 58. 18 3.48 .23 35.80 .46 1.84 57.33 5.06 34. 76 .32 2. 53 56.74 4.82 36.40 1.63 .41 55.73 6.61 Trace. 35. 16 .32 2.28 55.48 7. 69 .21 31.70 1.20 3.72 53.00 5. 85 2. 19 38.95 .01 174 THE DATA OF GEOCHEMISTRY. These analyses suggest, if they do not actually prove, a similarity of origin for all these bodies of water, and a possible derivation, direct or indirect, from a primitive ocean. Some of the lakes were formed by leaching masses of oceanic salts which were deposited in earlier geologic ages; others are doubtless remnants of oceanic over- flows or segregations. In the leaching process the alkaline chlorides dissolved more freely than other salts, and so became concentrated in the newer waters. K. Natterer , 1 in his discussion of the Persian salt lakes, suggests that differing diffusibility may have played a part in the concentration of sodium chloride. As the leaching waters percolated through the soil, the more diffusible alkaline chlorides would he partially separated from the less active calcium and mag- nesium salts, and would reach the lake reservoir in larger quantities. The composition of Lake Tekir-Ghiol, which is closely adjacent to the Black Sea, would seem to emphasize this suggestion. In it the alkaline chlorides are concentrated, while the other constituents of sea water are present in much less than the normal amounts. In direct relation to waters of the preceding group are the derived waters of the bittern type. In these, by prolonged evaporation, magnesium salts are concentrated, sodium chloride having crystal- lized out. The three waters available for comparison are as follows: Principal constituents of natural bitterns. Cl, Br, I. S0 4 . C0 3 . Na, K. Ca. Mg. Dead Sea (average) Red Lake 68.15 66.96 64. 22 0.28 Trace. 13.55 19.90 11.27 4.37 2.01 .10 13.62 11.13 17.55 Elton Lake 6.82 .04 From the chloride waters we pass by slow gradations to the sul- phate type, as shown in the following condensed analyses. Between the two groups there is no distinct line of demarcation. Principal constituents of chloro-sulphate waters. Sevier Lake Tamentica Lagoon Kisil-Kul Lake Parinacochas Lagoon of Epecuen Lake Tagar Lacu Sarat Lake Beisk Bitter Lake Lake Altai Old Wives Lake Laramie Lakes (average) Lake Domoshakovo Cl, Br. S0 4 . co 3 . Na, K. Ca. Mg. 52. 66 10. 88 33. 33 0. 12 3. 01 50. 44 9. 17 37. 64 .01 .60 48. 28 14. 55 0. 22 34. 36 .69 1. 86 46. 87 10. 59 2. 16 36. 47 1. 18 .82 42. 96 17. 19 2. 13 37. 72 29. 52 34. 99 1. 55 29. 42 .27 4. 12 28. 25 37. 12 .27 31. 75 .39 2. 16 22. 79 42. 32 .61 32. 33 .07 1. 86 20. 02 43. 63 1. 53 33. 16 .15 1. 28 14. 38 50. 14 1. 12 33. 35 .05 .90 4. 98 61. 86 1.54 30. 65 .97 4. 88 62. 34 29. 03 .68 1. 81 3. 71 63. 62 oo o 31. 20 .58 . 74 i Monatsh. Chemie, vol. 16, 1895, p. 666, THE WATERS OF CLOSED BASINS. 175 Some of these waters have been modified by human agency, which utilized them as sources of salt. They form, nevertheless, a natural series, in which the alkaline radicles are nearly constant in propor- tion, while the chlorides and sulphates vary reciprocally. Lake De Smet, a sulphate water from which chlorides are nearly absent, might be placed at the end of this series were it not for the small proportion of carbonates that it contains. A slightly different composition is represented by a subgroup of sulphato-chloride waters, as shown by the analyses of the Caspian, the Sea of Aral, and two smaller lakes. Principal constituents of sulphato-chloride waters. Cl, Br. so 4 . co 3 . Na,K. Ca. Mg. Barchatow bitter lake 45. 16 20. 23 28. 27 5. 84 Caspian Sea 41. 96 23. 88 0.*65 25. 16 2.44 5. 87 Biiluktii-Kul 38. 00 27. 39 .98 23. 61 5. 28 4. 68 Sea of Aral 35. 43 30. 98 .85 23. 18 4. 02 5. 50 Here we have a dilution of oceanic water by sulphate-bearing tribu- taries, with a falling off of the alkaline metals and an increase in calcium and magnesium. The bitterns derived from these waters differ from the normal bitterns in respect to their proportion of sul- phates, but otherwise they represent the same order of changes. I include with them the Schunett Lake of Siberia, which has analo- gous composition, and also the Issyk-Kul. Principal constituents of sulphato-chloride bitterns . Cl, Br. S0 4 . C0 3 . Na, K. Ca. Mg. Karaboghaz Gulf (average) 51. 86 16. 48 0. 07 18. 33 0. 28 11. 45 Tinetzky Lake 48. 12 21. 25 18. 70 . 01 11. 91 Schunett Lake 38. 89 32. 19 .31 16. 45 .44 11. 67 Issyk-Kul 15. 67 55.94 1. 26 13. 61 .94 12. 50 The water of Lake Chichen-Kanab in Yucatan is also a sulphato- chloride water, but it stands alone as the only known member of a distinct subgroup. Its dominant kation is calcium. The alkaline lakes that contain notable quantities of carbonates are less easy to classify than the foregoing waters, and yet some 176 THE DATA OF GEOCHEMISTRY. analogies are clear. First, we have a number of analyses in which the carbonates are largely in excess of all other salts, as follows : Principal constituents of carbonate waters . Cl, Br. SO*. co 3 . Na, K. Ca. Mg. Silver Lake 0. 87 2. 43 47.48 16. 36 11. 07 6. 59 Moses Lake 3. 88 2. 87 51. 56 19. 86 8. 41 7. 25 Malheur Lake 4. 55 7. 64 44. 63 29. 75 5. 58 4. 13 Lake Laach 4. 99 2. 97 50. 97 27. 05 9. 90 2. 77 Goodenough Lake 7. 64 7. 08 41. 41 42. 82 .02 .04 Black Lake 7. 68 13. 24 37. 79 41. 08 Palic Lake 15. 68 2. 92 41. 02 35. 75 .66 3. 35 In the next group of waters carbonates and chlorides predomi- nate, with sulphates in subordinate quantity. Principal constituents of carbonate-chloride waters. Bluejoint Lake Summer Lake Natron Lake Harney Lake (average) . Humboldt Lake Borax Lake Abert Lake (average)... Lonar Lake Pyramid Lake Salt Lake near Pretoria. Winnemucca Lake Cl, Br. SO*. co 3 . 13. 85 5.67 38. 68 18. 27 4. 18 35. 57 26. 00 32. 90 28. 95 8. 14 22. 82 31.82 3. 27 21. 57 32. 31 .13 22. 47 36. 13 1. 90 20. 73 40. 76 1.48 17. 63 41. 04 5. 25 14. 28 43. 47 .03 15. 17 47. 88 3. 76 7. 93 Na, K. Ca. Mg. 39. 96 0. 57 0. 63 41. 07 Trace. Trace. 31.05 3. 57 3. 62 39. 31 .01 .04 36. 51 1.35 1.88 - 39. 62 .03 .35 40. 62 Trace. Trace. 39. 71 .01 Trace. 35. 95 .25 2. 28 41. 33 38. 62 .55 .49 Borax Lake, which also contains 5.05 per cent of B 4 0 7 in its saline residue, might well be put in a class by itself ; but extreme subdivision is not now desirable. Two of the waters are conveniently classed as sulphato-carbonates, as follows: Principal constituents of sulphato-carbonate waters. Cl, Br. SO 4 . co 3 . Na, K. Ca. Mg. Omak Lake 2. 96 21. 12 36. 75 37. 12 0. 23 1. 82 Pelican Lake 7. 97 22. 09 30. 87 32. 83 2. 27 2. 62 In the following waters, which are of the “ triple” type, chlorides, sulphates, and carbonates are all present in notable quantities : THE WATERS OF CLOSED BASINS. 177 Principal constituents of “ triple ” waters. Cl, Br. SO*. 1 CO 3 . Na, K. Ca. Mg. Wilmington Lake 10. 78 16. 62 32. 75 39. 85 Soap Lake 13. 28 16. 44 30. 22 39. 60 Trace. 0. 04 Lake Huacachima 11. 18 16. 95 29. 33 41. 06 . 34 Owens Lake (average) 25. 30 9. 92 23. 59 39. 88 0 . 02 .01 Mono Lake 23. 34 12 . 86 23. 42 39. 78 .04 .10 Lake Van 27. 08 11. 95 20. 71 38. 84 . 57 Tulare Lake 20 . 26 20. 77 19. 55 38. 21 .28 .26 Lake Ruszanda 19. 07 22. 56 19. 22 38. 26 .20 .15 Walker Lake 23. 77 21. 29 17. 34 34. 83 .90 1. 56 Soda Lake (average) 35. 95 10. 42 14. 83 36. 00 . 22 Katwee Salt Lake 36. 67 12. 33 10. 42 40. 55 Finally there are three waters which might be classed with the sul- phato-chlorides, were it not for their moderately alkaline character. Principal constituents of water of Lake Biljo, Devils Lake , and Koko-Nor. Cl, Br. SO 4 . C0 3 . Na, K. Ca. Mg. Lake Biljo 9. 91 52. 33 6. 22 22. 70 0. 43 7. 28 Devils Lake 10. 45 54. 07 4. 24 25. 88 Trace. 5. 36 Koko-Nor 40. 09 17. 84 5. 55 31. 72 1. 77 2. 90 In general, as was pointed out in discussing the Lahontan waters, alkaline lakes are representative of volcanic regions, while saline lakes are associated with sedimentary deposits. That is, from a chemical point of view the alkaline waters are the newest, and exhibit the nearest relationship to rivers and springs. By the weathering of rocks carbonates are first formed, as is seen in most rivers near their sources. Under favorable conditions these salts accumulate and they are transformed into or replaced by other compounds only after a long and slow series of chemical reactions. In recently formed bodies of water, derived from igneous rocks, carbonates are abundant; but as salinity or concentration increases, the slightly soluble calcium carbonate is thrown down, leaving sulphates and chlorides in solution. If more calcium is available, gypsum is pre- cipitated, and the final result is a water containing little except chlorides. The carbonate waters form the beginning, the chloride waters the end of the series. When calcium is deficient in quantity, then mixed waters are produced, in which alkaline sulphates, car- bonates, and chlorides may coexist in almost any relative propor- tions. Waters of mixed type may also be formed by the blending of supplies from different sources, and the contributions of two tribu- taries may be very unlike. The fresh decomposition products from 97270°— Bull. 616—16 12 178 THE DATA OF GEOCHEMISTRY. a volcanic rock and the leachings of sedimentary beds are widely dissimilar; but the chemical changes consequent upon their com min - gling will follow the order just laid down. This order can not be stated in quantitative terms, for the conditions of equilibrium in complex mixtures are not definitely known. The solubility of a salt in pure water is one thing; its solubility in the presence of other compounds is something quite different; and when the number of possible substances is great the problem becomes hopelessly com- plicated. Each substance influences every other substance, in a manner which depends partly upon temperature and partly upon concentration, and no known equations can cover the whole field. Qualitatively, however, the conditions governing the deposition of salts can be simply and intelligibly stated. Suppose we consider a solution so dilute that it contains ions capable of forming the chlo- rides, sulphates, and carbonates of sodium, calcium, and magnesium, which are the chief salts derivable from natural waters. Upon con- centration, the difficultly soluble carbonates of calcium and magne- sium will be precipitated first, to be followed by the slightly soluble gypsum. Next in order sodium sulphate and carbonate will form, and these salts are deposited by many saline or alkaline waters. Later, sodium chloride and magnesium sulphate may crystallize out, leaving at last a bittern containing the very soluble chlorides of cal- cium and magnesium. This is the observed order of concentration, but every step is not necessarily taken in every instance. All of the calcium may be eliminated as carbonate, leaving none for the forma- tion of other salts. All of the sulphuric ions may be taken to produce gypsum, and then no sodium sulphate can form. In short, the actual changes which take place during the concentration of a specified water depend on the proportions of its constituents, and vary from case to case. The proposed order of deposition is simply the general order, which conforms to the facts of observation and to the known solubil- ities of the several salts. The least soluble possible salt will form first; the most soluble will remain longest in solution. The formation of double salts will be considered in another chapter. CHAPTER VI. MINERAL WELLS AND SPRINGS. DEFINITION. Between the so-called “ mineral waters” and waters of ordinary character no sharp line of demarcation can be drawn. In fact, some of the springs having the greatest commercial importance yield waters of exceptionally low mineral content and owe their value to their remarkable purity. They are simply potable waters carrying a minimum of foreign matter in solution. Other springs, on the con- trary, are characterized by excessive salinity, and between the two extremes nearly every intermediate condition may be observed. In the chapter on lakes and rivers a number of springs were con- sidered which represent the ordinary or common type of water sup- ply. Rain water, charged with carbonic acid, percolates through the soil or through relatively thin layers of rock and emerges with a moderate load of dissolved impurities. Upon evaporation such waters give a residue consisting most commonly of calcium carbonate, calcium sulphate, or silica, with minor amounts of alkaline chlorides, and, blending with rain or seepage waters, they form the beginnings of streams. Sometimes sulphates predominate, sometimes carbon- ates, but chlorides are present much less conspicuously. Calcium is the dominating metal, and sodium occupies, as a rule, a subordinate place. To the vast majority of spring waters these statements apply, but here and there exceptions are encountered which, by their peculiar characters, attract attention and are known as “ mineral” wells or springs. Speaking broadly, all springs are mineral springs, for all contain mineral impurities; but in a popular sense the term is restricted to waters of abnormal or unusual composition. A mineral water, then, is merely a water which differs, either in composition or in concentration, from the common potable varieties. The term is loose and indefinite, but it has a certain convenience, and we may use it without danger of being led astray. To put the case differently, a mineral spring may be described as one which owes its character to local as distinguished from wide- spread or general conditions; and the peculiarities thus acquired may result from a great variety of causes. One water, rising from beds of salt, is charged with sodium chloride; another represents the solution of gypsum; a third may carry substances derived from the sulphides of metalliferous veins, and so on indefinitely. Any soluble 179 * 180 THE DATA OF GEOCHEMISTRY. matter existing in the crust of the earth may find its way into the waters of a spring and give to the latter some distinguishing peculiar- ity. Even in their gaseous contents spring waters differ widely. Some are heavily charged with carbonic acid and effervesce upon reaching the air, and others contain hydrogen sulphide in sufficient quantities to be recognized by the smell. Some waters are strongly acid, some alkaline, and some neutral; waters emerging from beds of pyritiferous shale are often rendered astringent by salts of alumi- num or iron; one spring is boiling hot while its neighbors are ice cold; in short, every difference of origin may be reflected in some peculiarity of composition or character. In recent years many min- eral springs have been found to contain appreciable quantities of argon, helium, and the other inert gases, a fact which bears upon the radioactivity exhibited by natural waters. For example, G. Massol, 1 in the gas from the thermal spring of Uriage, France, found 0.932 per cent of helium, together with krypton and xenon. Argon was detected in the hot springs of Bath, England, shortly after the ele- ment was discovered. 2 In the boric acid sojjioni of Tuscany, helium and argon were found by R. Nasini, F. Anderlini, and R. Salvadori. 3 Many French springs have been studied, with similar results, by C. Moureu and R. Biquard. 4 These minor characteristics of natural waters can not be dwelt upon more fully here. CLASSIFICATION. The classification of waters can be based on a variety of considera- tions. It may be geologic, correlating the springs with their geologic origin, or as ancient or modern, or by dividing them into classes according to their derivation from rain water or from sources deep within the earth; it may be physical, drawing a chief distinction between cold and thermal springs; or chemical, in which case differ- ences of composition determine the place which each water shall occupy. To a great extent the three systems of classification over- lap, and each one depends more or less on the others; but for the purposes of this memoir, which deals with chemical phenomena, the chemical method is obviously the most appropriate. The other considerations must, of course, be taken into account; but chemical composition is, for us, the determining factor. From this point of view the classification of springs is comparatively simple and follows the lines laid down in the preceding chapters. Waters are classed according to their negative radicles, as chloride, sulphate, carbonate, 1 Compt. Rend., vol. 151, 1910, p. 1124. 2 See Rayleigh and Ramsay, Zeitschr. phys. Chemie, vol. 16, 1895, p. 362. Also Rayleigh, Proc. Roy. Soc., vol. 59, 1896, p. 198. s Gazz. chim. ital., vol. 28, 1898, p. 81. * Compt. Rend., vol. 143, 1906, p. 795; vol. 146, 1908, p. 435. See also Moureu, idem, vol. 142, 1906, p. 1155, and in Revue sci., 1914, p. 65, for a thorough review of the whole subject. MINERAL WELLS AND SPRINGS. 181 or acid waters, with various mixed types and occasional examples in which unusual combinations, such as nitrates, borates, sulphides, or silicates, appear. The classification, however, can not be rigid, and to a great extent convenience must govern and modify the usual rules. Mixtures such as we have now to consider can not be arranged according to any hard-and-fast system, but must be dealt with some- what loosely. The general relationships are simple and evident, but the exceptional cases are common enough to modify any formal scheme of arrangement that might be adopted. CHLORIDE WATERS. The literature relating to mineral springs is extremely volumi- nous, and the recorded analyses are numbered by thousands. From such a mass of material only typical or striking examples can be util- ized here in order to show the variations in composition which have been observed. As the chloride waters form perhaps the most con- spicuous group, we may properly begin with them, and consider first the solutions which upon evaporation yield principally sodium chlo- ride. Waters of this class are very common, and range from potable springs to brines resembling sea water in saline composition. From such brines common salt is commercially obtained, and the sub- joined table gives analyses of several important examples . 1 The figures represent the composition of the anhydrous saline matter con- tained by the several waters, each analysis being reduced from the original form of statement to percentages of ions. 1 In Ann. Kept. Geol. Survey Canada, vol. 15, 1902-3, p. 236 S, G. C. Hoffman gives 12 analyses of brines from Manitoba. A brine from a well 1,920 feet deep, at Sand Beach, Michigan, analyzed by S. P. Duffield (Geol. Survey Michigan, vol. 5, pt. 2, 1895, p. 82), is unusually rich in bromine. J. W. Turrentine, U. S. Dept. Agric., Bur. Soils Bull. No. 94, 1914, gives many analyses of American brines and bitterns. For the brines of Silver Peak Marsh, Nevada, see R. B. Dole, U. S. Geol. Survey Bull. No. 530, pp. 331-345, 1913. 182 THE DATA OF GEOCHEMISTRY. Analyses of natural brines. A. Brine from Syracuse, New York. Average of four analyses by C. A. Goessmann, published in Dana’s System of mineralogy, 6th ed., p. 156. B. Brine from Warsaw, New York. Analysis by F. E. Engelhardt, Bull. New York State Mus. No. 11, 1893, p. 38. Many other analyses are given in this publication. C. Brine from East Saginaw, Michigan. Well 806 feet deep. Analysis by Goessmann, Geol. Survey Michigan, vol. 3, 1873-1876, p. 183. D. Brine from Pomeroy, Ohio. - Analysis by C. W. Foulk, Bull. Ohio Geol. Survey No. 8, 1906, p. 27. The trace of iodine represents 0.004 gramme Nal per liter. E. Humboldt salt well, Minnesota. Analysis by C. F. Sidener, Ann. Rept. Geol. Survey Minnesota, vol. 13, 1884, p. 101. F. Brine from Hutchinson, Kansas. Analysis by E. H. S. Bailey and E. C. Case, Univ. Kansas Geol, Survey, vol. 7, 1902, p. 79. G. Artesian well, Abilene, Kansas. Analysis by E. H. S. Bailey and F. B. Porter, Univ. Kansas Geol. Survey, vol. 7, 1902, p. 130. WeU 1,260 feet deep. H. Bryan’s well, Bistineau, Louisiana. Analysis by M. Bird, Report on geology of Louisiana, 1902, p. 40. Many other analyses of salines are given in this volume. The brines are of Cretaceous origin. Cl. Br. I.. S0 4 C0 3 P0 4 Na K Ca Sr Ba Mg Mn Fe" Fe 2 0 3 A1 2 0 3 Si0 2 Other solids . Salinity, per cent. 58. 85 .01 2. 29 .01 37. 29 .03 1.28 .23 .'6i' 100 . 00 16. 84 59. 71 1. 19 38. 38 ’*.*67 .05 100. 00 26. 34 61. 27 .52 32. 76 ’ 4 .' 25 ' 1. 20 100 . 00 20. 24 61. 59 .13 Trace. None. 31. 51 .06 4. 91 .14 .21 1. 36 55. 96 .08 .01 100. 00 10. 52 4. 18 1. 68 Trace. 32. 56 .66 2. 71 1. 80 .02 .07 .36 100 . 00 5. 72 59. 60 1. 33 38. 38 .55 11 03 100. 00 29. 31 61. 65 .29 Trace. .07 31. 57 Trace. 4. 85 1. 52 Trace. . 05 Trace, 100. 00 17. 89 59. 96 37. 20 .94 29 63 98 100. 00 8. 93 Most if not all of the foregoing brines were formed by solution from beds of rock salt. The latter undoubtedly originated from the evaporation of salt lakes or sea water, and in geological age they range from the Cretaceous down to the upper Silurian. The New York brines are from Silurian deposits. The Humboldt well is nearest to ocean water in composition, although it is nearly twice as concentrated. In general, the proportion of sodium chloride is greater than in sea salts, for the reason that that compound redis- solves more readily than the gypsum which was deposited with it. The process of deposition and re-solution thus tends to separate the constituents of the original water; and so the composition of the ancient lake or ocean is not exactly reproduced. The following analyses also represent the salts from chloride waters in which sodium is largely the predominant base: MINERAL WELLS AND SPRINGS, 183 Analyses of chloride waters — I. A. Cincinnati artesian well, Cincinnati, Ohio. Analysis by E. S. Wayne, cited by A. C. Peale, in Bull. U. S. Geol. Survey No. 32, 1886, p. 133. This water contains considerable quantities of free H 2 S and C0 2 . B. Upper Blue Lick Spring, Kentucky. Analysis by J. F. Judge and A. Fennel, cited by Peale, op. cit., p. 111. Also rich in H 2 S and C0 2 . I represent here by X an indeterminate mixture of Ca 3 P 2 08, A1 2 0 3 , and Fe20 3 . For later analyses of the Blue Lick springs, by R. and A. M. Peter, and for analyses of other mineral waters in Kentucky, see Chase Palmer, Water-Supply Paper U. S. Geol. Survey No. 233, 1909, pp. 184-215. C. Montesano Springs, Missouri. Analysis by P. Schweitzer, Geol. Survey Missouri, vol. 3, 1892, p. 77. This volume contains many analyses of Missouri mineral waters. D. Deep well at Brunswick, Missouri. Depth 1,505 feet. Analysis by Schweitzer, op. cit., p. 97. E. Utah Hot Springs, 8 miles north of Ogden, Utah. Temperature 55° C. Analysis by F. W. Clarke. Bull. U. S. Geol. Survey No. 9, 1884, p. 30. F. Spring at Pahua, New Zealand. Analysis by W. Skey, Trans. New Zealand Inst., vol. 10, 1877, p. 423. This spring is notable from the fact that it contains free iodine. According to J. A. Wanklyn (Chem. News, vol. 54, 1886, p. 300) the water of Woodhull Spa, near Lincoln, England, has the same peculiarity. The iodine colors the water brown and can be extracted by carbon bisulphide. In analyses D and F the bicarbonates of the original statement have been reduced to normal salts. A B C D E F Cl 55. 83 53. 08 57. 38 52. 74 58. 79 60. 78 Br .04 . 51 .31 Trace. Trace. I, combined .03 .02 . 04 I, free . 11 S0 4 3. 12 6.03 5. 37 8. 36 . 94 . 15 co 3 2. 63 2. 34 1. 88 .61 . 17 P0 4 . 05 Na 33. 09 31. 47 28. 17 30. 15 30. 38 34. 81 K .27 .96 .15 3. 76 .02 Li Trace. Ca 3. 72 3. 56 6. 15 4. 74 4. 90 3. 14 Mg 1. 13 1. 57 2. 30 2. 09 .40 . 60 A1 .01 A1 2 0 3 .02 Fe // Trace. FeoCb .06 Si0 2 .08 . 16 .17 .04 .20 .12 X .30 Salinity, parts per million 100. 00 10, 589 100. 00 11, 068 100. 00 8, 509 100. 00 15, 905 100. 00 23, 309 100. 00 21, 060 184 THE DATA OF GEOCHEMISTRY. Analyses of chloride waters — I — Continued. G. Water of Salsomaggiore, Italy. Analysis by R. Nasini and F. Anderlini, Gazz. chim. ital., vol. 30, i, 1900, 305. Contains in 1,000 grams 0.00223 gram Mn and 0.00792 gram B 4 O 7 . These are less than 0.01 per cent of the total solids. H. The Marienquelle, Bavaria. Analysis by A. Lipp, Ber. Deutsch. chem. Gesell., vol. 30, 1897, p. 309. Contains also much free C0 2 . I. The Kochbrunnen, Wiesbaden, Germany. Analysis by C. R. Fresenius, Jahrb. Nassau. Ver. Natur- kunde, vol. 50, 1897, p. 20. This water also contains 0.000013 gram iodine, 0.00002 gram PO 4 , and 0.00016 gram ASO 4 to the liter, each recorded here as a “ trace.” For other analyses of Wiesbaden waters see the same journal, vol. 49, 1896, pp. 22, 23. J. Water of Arva-Polhora, Hungary. Analysis by W. Kalmann and M. Glaser, Min. pet. Mitt., vol. 18, 1898-99, p. 443. Organic matter, about 0.15 per cent, is excluded from the reduced statement here given. K. Old sulphur well, Harrogate, England. Analysis by T. E. Thorpe, Jour. Chem. Soc., vol. 39, 1881, p. 500. The memoir contains some other analyses. L. Chloride of Iron Spa, Harrogate. Analysis by C. H. Bothamley, Jour. Chem. Soc., vol. 89, 1881, p. 502. The same author, in vol. 63, 1883, p. 685, gives analyses of waters from Askem, Yorkshire. G H I J K L Cl 61. 09 52. 72 56. 58 58. 76 58. 81 60. 83 Br . 15 .42 .04 . 37 . 19 .07 I .03 .54 Trace. . 14 .01 Trace. F Trace. S0 4 .18 Trace. .78 .12 .02 S . 23 CO, 7. 66 3. 13 1. 07 2. 12 1. 23 P0 4 Trace. Trace. .02 Trace. As0 4 Trace. B 4 0 7 Trace. Trace. .72 bo 2 . 01 Na 34.04 33. 08 32. 60 36. 18 33. 61 23. 45 K Trace. 1. 16 .42 .48 . 35 Li . 07 Trace. .04 .22 .01 Trace. nh 4 ; . 12 . 07 .03 .03 Ca 3. 21 4.15 4. 05 1. 10 2. 65 7. 28 Sr .24 . 12 .34 Trace. . 07 Ba . 01 . 08 . 42 . 76 Mg .82 1. 34 . 61 .29 1. 37 3. 12 Mn . 10 Fe" .03 }> . 04 ) .14 2. 39 Fe 2 0 3 . 09 A1 .01 Trace. Trace. Cu Trace. Si0 2 .01 .76 .03 .07 .30 Salinity, parts per million 100.00 159, 000 100. 00 2, 970 100.00 8, 241 100.00 30, 150 100.00 14, 800 100.00 6, 617 Although sodium chloride is the principal salt obtainable from the waters represented by the preceding analyses, they owe their interest to other things. They have been selected from the great mass of published material in order to show the extent to which substances like bromine, iodine, sulphur, lithium, barium, strontium, and iron occur in waters of this class . 1 To these minor constituents the therapeutic value of mineral waters is commonly ascribed, but to considerations of that sort no attention 1 For the common occurrence of Sr, Ba, Mn, As, etc., in mineral springs see J. C. Gil, Rev. Acad, ci Madrid, vol. 8, 1909, p. 131. On selenium in mineral waters see F. Taboury, Bull. Soc. chim., 4th ser., vol. 5, 1909, p. 865. MINERAL WELLS AND SPRINGS. 185 can be paid here. The last analysis given, that of the Chloride of Iron Spa at Harrogate, is interesting as marking a transition to another group of chloride waters, in which the proportion of sodium is decreased and large quantities of calcium appear. Sometimes magnesium is also abundant; for example, in salts from the group of springs at Kapouran, Java, S. Meunier 1 found 54.2 per cent of calcium chloride and 40.65 per cent of magnesium chloride. The following analyses are characterized by the presence of calcium in large proportion : 2 Analyses of chloride waters — II. A. Brine from well 2,667 feet deep at Conneautsville, Pennsylvania. Analysis by A. E. Robinson and C. F. Mabery, Jour. Am. Chem. Soc., vol. 18, 1896, p. 915. A little H 2 S is present. B. Well at Bowerman’s mills, Whitby, Canada. Analysis by T. Sterry Hunt, Geology of Canada, 1863, p. 547. Analyses of other waters are given in this memoir. C. Water from well 192 feet deep, Manitoulin Island, Lake Huron. Analysis by T. Sterry Hunt, Chem- ical and geological essays, 1875, p. 158. D. Water from the Silver Islet mine, Lake Superior. Analysis by F. D. Adams, Ann. Rept. Geol. Survey Canada, new ser., vol. 1, 1885, p. 17 M. E. Water from the lower level of the Quincy mine, Hancock, Michigan. Analysis by G. Steiger in the laboratory of the United States Geological Survey. F. Waterfrom boring on Kanab Creek, near Port Haney, British Columbia. Analysis by F. G. Wait, Ann. Rept. Geol. Survey Canada, vol. 5, ii, new ser., 1890-91, p. 22 R. G. Boiling spring at Savu-Savu, Fiji. Analysis by A. Liversidge, Proc. Roy. Soc. New South Wales, vol. 14, 1880, p. 147. Part of the aluminum in this water is reported as A1C1 3 and part as A1 2 0 3 . H. W ater from People’s N atural Gas W ell, 8 miles southwest of Imperial, W ashington County, Pennsyl- vania. Specific gravity, 1.211. Depth of well when sample was taken, 6,300 feet. Analysis by G. Steiger in the laboratory of the Survey. A B c D E F G H Cl 62. 31 64. 43 64. 15 61. 57 63. 55 63. 39 57. 91 61. 38 Br .53 .41 . 26 I .01 Trace. Present Trace. so 4 . . .03 . 13 .01 None. 3. 38 . 02 C0 3 .27 .09 .48 . 01 Trace. None. P0 4 ... None. Trace. J- V4. - Na 18. 35 16. 17 8. 71 18. 33 5. 63 5. 27 16. 65 24. 50 K 1. 55 Trace. 1.92 .67 None. .42 .93 1. 97 Li .04 nh 4 .23 Ca 13. 86 13. 68 20. 67 17. 46 30. 78 30. 89 18. 34 9. 56 Sr Trace. 1. 31 Mg 2. 53 5. 22 4. 25 1. 21 .01 .03 .04 .94 A1 .02 None. None. . 43 A1 2 0 3 . 54 Fe" .25 Trace. None. None. Trace. .06 Fe 2 0 3 Mn, Co Trace. None. Si0 2 .02 .15 .01 1. 78 Salinity, parts per million 100. 00 309, 175 100. 00 46, 300 100. 00 21, 660 100. 00 36, 000 100. 00 212, 300 100. 00 48, 500 100. 00 7, 813 100. 00 263, 640 1 Compt. Rend., vol. 103, 1886, p. 1205. 2 See also the analysis of brinefrom a well at Alma, Michigan, by C. F. Chandler and C. E. Pellew, Geol. Survey Michigan, vol. 5, pt. 2, 1894, p. 46. Also one of water from the Freda well, Keweenaw Point, Michi- gan, by G. A. Konig, Rept. State Board Geol. Survey Michigan, 1903, p. 165. In the deep-seated waters around Lake Superior calcium chloride seems to be an important constituent. These waters have been carefully studied by A. C. Lane, Jour. Canadian Min. Inst., vol. 12, 1909, p. 114, and Proc. Lake Superior Min. Inst., 1908, p. 63. 186 THE DATA OF GEOCHEMISTRY. The water represented by analysis H is remarkable for its high pro- portion of strontium — 3.55 grams per kilogram, equivalent to 6.8 grams of SrCl 2 per liter. A trace of barium was also detected in the water. The next table contains analyses of waters belonging to the chloride group, but in which notable quantities of other acid radicles are also present. The chlorine, however, predominates. Analyses of chloride waters — III. A. Congress Spring, Saratoga, New York. Analysis by C. F. Chandler, cited by A. C. Peale in Bull. U. S. Geol. Survey No. 32, 1886, pp. 38, 39. B. Hathom Spring, Saratoga, New York. Analysis by Chandler, loc. cit. For recent analyses of the Hathom and twelve other Saratoga waters, see J. K. Haywood and B. H. Smith, Bull. Bur. Chemistry No. 91, U. S. Dept. Agr., 1905. For 5 more analyses see L. R. Milford, Jour. Ind. Eng. Chem., vol.6, 1914, p. 207. C. Franklin artesian well, Ballston, New York. Analysis by Chandler, op. cit., p. 33. These waters (A, B, and C) are all reported as containing bicarbonates, which in the present tabulation are reduced to normal salts. They all effervesce because of their large content in free C0 2 . The P0 4 in A and C amounts to 0.01 grain per gallon. D. Artesian well at Louisville, Kentucky. Analysis by J. Lawrence Smith, cited by Peale, op. cit., p. 115. Bicarbonates reduced to normal salts. Lithium is reported as 0.02 grain per gallon. E. Steamboat Springs, Nevada. Analysis by W. H. Melville, given by G. F. Becker in Mon. LT. S. Geol. Survey, vol. 13, 1888, p. 349. Bicarbonates reduced to normal salts. The “ trace” of iron represents 0.14 part per million. From a geological point of view this water is out of its proper classification. It is a volcanic water, whereas the other waters in the table are of sedimentary origin. F. Lansdowne well, Cheltenham, England. Analysis by T. E. Thorpe, Join. Chem. Soc., vol. 65, 1894, p.772. The “trace” of bromine is 0.3part and that ofiron 0.1 part per million. G. The Stanislawaquelle, near Karlsdorf, Galicia. Analysis by Von Dunin-Wasowicz and J. Horowitz, Chem. Centralbl., 1899, pt. 2, p. 491. Bicarbonates reduced to normal salts. The N0 3 amounts to 0.02 part per million. One kilogram of this water contains 2.157232 grams of free C0 2 and 0.10665 gram of organic matter. A B c D E F G Cl 42. 00 42. 42 41. 95 48. 03 35. 00 38. 01 34. 60 Br 1. 13 . 16 . 37 .05 Trace. I .02 .02 . 02 .04 Trace. \ .02 F. .. Trace. Trace. Trace. ) S0 4 . . . 08 . 04 14. 93 4. 58 20. 89 .82 s .22 co 3 18. 59 19. 28 18. 66 .49 5. 08 4. 22 19. 96 no 3 Trace. P0 4 Trace. Trace. Trace. .09 .03 Trace. b 4 o 7 Trace. Trace. Trace. 8. 88 Na 27. 62 27. 29 28. 84 29. 84 30. 35 32. 80 37. 29 K . 78 .68 1. 83 .41 3. 79 .72 .53 Li .08 .16 .07 Trace. .27 Trace. .01 Ca 6.03 5. 69 5. 04 3. 75 .25 1. 85 3.64 Sr Trace. Trace. Trace. 1. 44 Ba . 09 . 12 .06 .82 Mg 3. 41 3. 92 2. 95 2. 19 .01 1. 37 Mn Trace. .01 Fe" Trace. Trace. Fe 2 0 3 . 03 . 07 . 07 . 02 . 17 A1 .06 Trace. A1 2 0 3 Trace. .02 . 03 .01 As . 10 Sb .02 Trace. Sif> 2 . 14 .17 .07 .10 11.41 .14 .69 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 100.00 Salinity, parts per million 12, 022 15, 238 20, 315 15,700 2, 850 8, 870 7, 639 MINERAL WELLS AND SPRINGS. 187 SULPHATE WATERS. The sulphate waters, or the waters in which S0 4 is the principal negative ion, fall, like the chloride waters, into several groups, which shade one into another by imperceptible gradations. Among potable waters of this class, those which upon evaporation yield chiefly cal- cium sulphate are by far the most common. Many examples of such waters were cited among the analyses of rivers. As a rule, on account of the slight solubility of gypsum, their salinity is relatively low. Waters of this type are frequently found in so-called mineral springs. Other waters of medicinal significance are essentially solutions of magnesium sulphate or sodium sulphate; still others contain sul- phates of aluminum or iron, and a small group of waters, derived from the oxidation of sulphides, carry heavy metals in considerable quantity. Examples of these different classes are given below, and some sulphate waters which contain free acids will be considered in a special group later. The following analyses are sufficient for pres- ent purposes : Analyses of suljphate waters. A. Abilena well, 14 miles northwest of Abilene, Kansas, 130 feet deep. Analysis by E. H. S. Bailey, Univ. Geol. Survey Kansas, vol. 7, 1902, p. 166. The ‘‘traces” refer to 4 parts N0 3 and 3.2 parts Fe per million of water. B. Spring near Denver, Colorado. Analysis by L. G. Eakins, Bull. U. S. Geol. Survey No. 60, 1890, p. 174. Contains 210 parts of free CO 2 per million. C. Cottage well, Cheltenham, England. Analysis by T. E. Thorpe, Jour. Chem. Soc., vol. 65, 1894, p. 772. Contains 0.2 part of Fe per million. D. Bitter spring at Laa, Austria. Analysis by A. Kauer, Jahrb. K.-k. geol. Reichsanstalt, vol. 20, 1870, p. 118. Contains free CO 2 . E . Water from Cruzy, Hdrault, France. Analysis published by Braconnier, Annales des mines, 8th ser., vol. 7, 1885, p. 143. From a well 14 meters deep in an old gypsum quarry. The fissures around the well are lined with fibrous epsomite. F. St. Lorenzquelle, Leuk, Switzerland. Analysis by G. Lunge and R. E. Schmidt, Zeitschr. anal. Chemie, vol. 25, 1886, p. 309. Contains 0.06 part Li, 0.05 part NIL, 0.05 part Fe, and 0.11 part Mn per mil- lion— in each case less than 0.01 per cent of the total solids. A B C D E F Cl 0. 48 2. 62 6. 56 0. 57 3. 73 0. 34 so 4 66. 28 72. 56 57. 42 69. 87 74. 16 65. 86 co 3 . 60 6. 48 4. 75 .03 3. 74 no 3 Trace. .02 PO, Trace. As Trace. Na 30. 46 11.23 13. 51 2. 99 4. 50 1. 50 K 1.08 .22 .48 .35 .03 . 30 Li Trace. Trace. Trace. nh 4 . 01 .22 Trace. Ca .67 .53 8.33 7. 63 .02 23. 55 Sr . 05 Ba Trace. Mg .41 12. 79 7. 03 13. 18 17. 45 3. 07 1 Mn Trace. Trace. Fe" Trace. Trace. } * 01 Fe 9 0o } .02 .01 ) ALo, .03 Al. Trace. ) Cu Trace. Si0 2 .02 .05 .16 .42 .07 1.55 Salinity, parts per million 100. 00 74, 733 100. 00 60, 584 100. 00 5, 518 100. 00 62, 371 100. 00 101, 000 100. 00 1, 948 188 THE DATA OF GEOCHEMISTRY. Analyses of sulphate waters — Continued. G. Spring at Srebrenica, Bosnia. Analysis by E. Ludwig, Min. pet. Mitt., vol. 11, 1889-90, p. 303; 1.37 per cent of free H2SO4 has been here added to the figure for the SO 4 radicle. A little organic matter (11.2 parts per million) is also present. On p. 308 of the same volume Ludwig gives an analysis of an acid water rich in aluminum sulphate from Biidos, Transylvania. Other papers in the volume give a number of important analyses of springs in Bosnia and Transylvania. Some waters containing unusual amounts of strontium are mentioned in Rept. State Board Geol. Survey Michigan, 1905, p. 555. H. Alumweil, Versailles, Missouri. Analysis by P. Schweitzer, Geol. Survey Missouri, vol. 3, 1892, p. 131. I. Water from Roncegno, southern Tyrol. Analysis by M. Glaser and W. Kalmann, Ber. Deutsch. chem. Geseil., vol. 21, 1888, p. 2879. For a later analysis of Roncegno water see R. Nasini, M. G. Levi, and F. Ageno, Gazz. chim. ital., vol. 39 (2), 1909, p. 481. They cite another analysis by P. Spica. J. Arsenical spring, S. Orsola, southern Tyrol. Analysis by C. F. Eichleiter, Jahrb. K.-k. geol. Reichs- anstalt, vol. 57, 1907, p. 529. The trace of Ni is 0.003 per cent. K. Spring on Shoal Creek, 4| miles west of Joplin, Missouri. Analysis by W. F. Hillebrand, Bull. U. S. Geol. Survey No. 113, 1893, p. 49. Total CO 2 , free and combined, 120.5 parts per million. A trace of lead is also reported. The water of Spring River, in eastern Kansas, also contains zinc, derived from the drain- age of adjacent mines. See E. H. S. Bailey, U. S. Geol. Survey Water-Supply Papers Nos. 273, 351, 1911. Cl 50 4 .. .. C0 3 ... P0 4 .... h 3 as0 4 As 0 2 . . Na K Li Ca Mg.... M 11 Fe"... Fe /// ... A 1 Co.... Ni.... Cd.... Zn.... Cu.... 510 9 . . . Salinity, parts per million . 0. 48 65. 33 Trace. .41 .31 .32 Trace. 3. 00 1. 48 .12 24. 98 1.21 .30 .36 1. 70 100. 00 1,723 76. 57 1. 19 5. 82 3. 39 4. 28 ’7.' 36 1.39 100. 00 3, 303 0. 03 70. 93 .23 1. 93 1.25 .23 7. 08 .93 .78 .03 11. 09 3. 09 .17 .41 .06 .15 1. 61 100. 00 8, 150 0. 33 71. 84 .75 .14 .21 .10 6. 32 .97 .24 1. 76 13. 09 3. 05 Trace. .01 1. 19 100. 00 7, 683 0. 48 52. 76 8.00 .67 .46 11.32 .71 .42 .11 * . 08 .10 22.31 .04 2.54 100.00 540 The Roncegno and S. Orsola waters evidently derive their saline constituents from metallic sulphides, apparently in great part from arsenical pyrites. Arsenical waters are not uncommon, and some of them contain enough arsenic to be poisonous. The water from Shoal Creek represents the oxidation of zinc blende, together with some reaction upon the adjacent limestones, from which its calcium and carbonic ions were obtained. It is essentially the same thing as a mine water, although it is not derived from any artificial opening. For comparison, three analyses of mine waters, carried out in the laboratory of the Geological Survey, are appended. Two of them are zinc waters; the third is a strong solution of copper sulphate. Such waters play an important part in the leaching and reprecipitation of ores and will be more fully considered later. MINERAL WELLS AND SPRINGS. 189 Analyses of mine waters . 1 A, B. Two mine waters from the Missouri zinc region, analyzed by H. N. Stokes. Two similar waters from the same region were analyzed by C. P. Williams, Am. Chemist, vol. 7, 1877, p. 246. C. Water from the Mountain View mine, Butte, Montana. Analysis by W. F. Hillebrand. Specific gravity, 1.1317 at 15° C. Contains, in parts per million, 3.5 Ni, 4.6 Co, 6.8 K, and 1.5 PO 4 . A B C • Cl 0. 16 0. 03 0. 01 so 4 64.47 63. 26 60 29 Pol Trace. As0 4 Trace. Na 1. 14 .50 .04 K . 10 Trace. Trace. Li Trace. None. Trace. Ca 14. 38 3.55 .26 Mr 1. 36 .26 .13 Mn .08 .02 .01 Fe" 6.49 4. 88 .04 Ni Trace. Co Trace. Zn 10. 74 24. 80 .37 Cu Trace. .04 38. 72 Cd .02 .09 Al .20 1. 46 .07 Si0 2 .86 1.11 .06 Salinity, parts per million 100. 00 4, 232 100. 00 9, 754 100. 00 117, 850 Two other examples of intermediate waters, containing both sul- phates and chlorides, but with the former in excess, may be cited here. Both are from Indiana, and the analyses are by W. A. Noyes. Analyses of sulphato-chloride waters. A. King’s mineral spring, near Dallas. Twenty-sixth Ann. Kept. Indiana Dept. Geology, 1901, p. 32. Contains traces of Al, Fe, Ba, Sr, Li, Mn, Ni, Zn, Br, P.O4, and B4O7. This volume contains an elaborate report upon the mineral waters of Indiana, in which many other analyses are cited. B. West Baden Spring. Op. cit., p. 109. Contains traces of Al, Fe, Ba, Sr, Li, Br, I, PO4, and B 4 O 7 . Also 32.5 parts of H 2 S per million of water. A B Cl 11. 10 18. 19 so 4 59. 68 46. 66 co 3 1. 67 4. 11 Na 13. 89 11. 72 K .49 . 78 Ca 2. 91 13. 16 Mr 10. 19 5. 21 SiO., .07 . 17 Salinity, parts per million 100. 00 15, 682 100. 00 4, 417 For other analyses of mine waters see Chapter XV of this memoir. 190 THE DATA OF GEOCHEMISTKY. CARBONATE WATERS. The carbonate waters, those in which C0 3 or HC0 3 is the principal negative ion, fall into two main subdivisions, calcium being the im- portant base in one and sodium in the other. A large number of lake and river waters, as we have already seen, belong to the first of these groups, and so do many springs of the usual potable type; waters of the second group, however, are not uncommon. In most of these waters the carbonic acid present is sufficient to form bicarbon- ates — a condition which renders it possible for calcium, magnesium, and iron to remain in solution. Upon evaporation of such waters, CaC0 3 and MgC0 3 are deposited, while the ferrous bicarbonate is broken up, and insoluble Fe 2 0 3 , or some corresponding hydroxide, is formed by oxidation. The anhydrous residue in such cases contains no bicarbonates, but the latter may exist when sodium is predomi- nant. The salt NaHC0 3 is moderately stable. On account of these peculiarities, which characterize the carbonate waters, it seems best to state their analyses in two ways — one with bicarbonate ions (when they are given) in terms of parts per million, the other in percentages of anhydrous residue, as in all the preceding tables. Each form of statement has its advantages, but the second method gives the best comparison between different waters. The following analyses repre- sent waters of the carbonate type: 1 1 Some interesting carbonate waters from Colorado are described by W. P. Headden in Am. Jour. Sci., 4th ser., vol. 27, 1909, p. 305. MINERAL WELLS AND SPRINGS. 191 Analyses of carbonate waters. A. McClelland well, Cass County, Missouri. Analysis by P. Schweitzer, Geol. Survey Missouri, vol. 3, 1892, p. 181. B. Artesian water, La Junta, Colorado. Well 386feet deep. Analysis by W. F. Hillebrand in the labo- ratory of the United States Geological Survey. C. Ojo Caliente, near Taos, New Mexico. Analysis by Hillebrand, Bull. U. S. Geol. Survey No. 113, 1893, p. 114. Traces of As, NO 3 , Ba, NH 4 , and possibly I, were found. For the geologic relations of Ojo Caliente see W. Lindgren, Econ. Geology, vol. 5, 1910, p. 22. D. The Grande-Grille, Vichy, France. Analysis by J. Bouquet, Annales chim. phys., 3d ser., vol. 42, 1854, p. 304. Analyses of other Vichy waters and their sediments are given in this memoir. E. Spring at Hikutaia, Puriri, district of Auckland, New Zealand. Analysis by W. Skey, Trans. New Zealand Inst., vol. 10, 1877, p. 423. F. Excelsior Springs, Missouri. Analysis by W. P. Mason, Chem. News, vol. 61, 1890, p. 123. This water is notable for the relatively large amount of manganese which it contains. G. Spring in Pine Creek valley, near Atlin, British Columbia. Analysis by F. G. Wait, Ann. Rept. Geol. Survey Canada, 1900, p. 49 It. This water deposits hydromagnesite and calcareous tufa. H. Wilhelmsquelle, Karlsbrunn, Austrian Silesia. Analysis by E. Ludwig, Min. pet. Mitt., vol. 4, 1882, p. 182. I.— Parts per million of water. A B c D E F G H Cl 94 66.9 231.4 324 190.2 11. 98 1. 5 1. 09 I Trace. F 5.2 so 4 88 71.1 151.0 197 47.9 2. 68 60.2 6. 48 s 1 co 3 791.5 i, 095. 9 2, 392 273. 75 hco 3 1, 287 5, 305. 8 Present. 6. 79 6, 339. 1 Trace. 405. 18 P0 4 .2 80 .54 As0 4 Trace. 2 Trace. B 4 0 7 4. 2 Trace. Na 581 668. 7 995. 7 1, 851 151 1, 897. 1 31. 6 9.51 51. 9 5. 24 K 6.4 31.4 3. 65 12.0 1. 76 Li Trace. 3.4 Trace. Trace. Ca 4 4.4 22.8 120 100.6 145. 10 116.8 66. 27 Sr 1.4 2 Trace. Mg 2 2.5 9.5 58 60.2 15. 63 1, 152. 3 18. 85 Mn Trace. 4. 50 .05 Fe" 2.4 Trace. 11.31 6. 7 46. 57 Fe 9 0, 1. 6 2 A1 2 0 3 3.4 . 5 2. 10 6.5 . 30 Si0 2 12 51.0 60.2 70 39,6 12. 00 82.5 69. 36 2, 069 1, 668. 3 2, 614. 4 5, 249 7, 673. 1 489. 00 7, 829. 5 621. 69 192 THE DATA OF GEOCHEMISTRY. II. Percentage of total solids, all carbonates normal. A B c D E F G H Cl 6. 63 4. 01 8. 85 6. 17 3. 84 2. 42 0. 03 0. 28 I Trace. F . 19 so* 6. 21 4. 26 5. 77 3. 75 .98 .54 1. 31 1. 68 s. .06 co 3 44. 76 47.45 41. 91 45. 57 52. 09 55. 92 67. 56 38. 72 . 14 P0 4 .01 1. 52 Present. Trace. As0 4 .04 Trace. B 4 0 7 . 16 Trace. Na 41. 07 40. 09 38. 08 35. 27 38. 39 1. 92 1. 13 1. 36 K .38 1. 20 2.88 . 64 .73 .26 . 46 Li Trace. . 12 Trace. Trace. Ca .30 .27 .87 2. 29 2.04 29. 28 2. 54 17. 18 Sr .05 . 04 Trace. Mg .12 . 15 . 41 1. 11 1.22 3. 15 25. 03 4. 89 Mn Trace. None. . 91 .01 Fe" .14 Trace. 2. 28 Fe 9 0o . 06 .04 . 21 17. 24 A1 2 0 3 . 20 .02 . 43 . 14 . 07 Si0 2 .85 3. 05 2. 30 1.32 o CO 2. 42 1. 79 17. 97 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 The water of Ojo Caliente is noticeable on account of its content of fluorine. This element is rarely determined in water analyses, but is almost invariably present. According to A. Gautier and P. Clausmann, 1 its quantity in spring waters ranges from 0.30 to 6.32 milligrammes per liter, being highest in waters issuing from areas of eruptive rocks. The highest values of all were found in the waters of Vichy. 2 1 Compt. Rend., vol. 158, p. 1631, 1914. 2 According to De Gouvenain (Compt. Rend., vol. 76, 1873, p. 1063), Vichy water contains 7.6 parts of fluorine per million. In the water of Bourbon-rArchambault 2.68 parts of fluorine were found. For other examples of water containing fluorine see J. C. Gil, Mem. Acad. Barcelona, vol. 1, 1896, p. 420; A. F. de Silva and A. d’Aguiar, Bull. Soc. chim. ,3d ser., vol. 21, 1899, p. 887; C. Lepierre, Compt. Rend., vol. 128, 1899, p. 1289; J. Casares, Zeitschr. anal. Chemie, vol. 34, 1895, p. 546; vol. 44, 1905, p. 729; and P. Carles, Compt. Rend., vol. 144, 1907, p. 37. Carles rarely failed to detect fluorine in mineral waters, commonly from 0.002 to 0.004 gram per liter. In one Vichy water he found 0.018 gram, his maximum. This is 18 parts per million. MINERAL WELLS AND SPRINGS. 193 WATERS OF MIXED TYPE. The following analyses, which are all reduced to the normal stand- ard, represent waters of mixed type, chlorides with carbonates; sul- phates with carbonates; or chlorides, carbonates, and sulphates all together. Waters of this character are very common, and show almost every stage of intermediate gradation. Analyses of waters of mixed type. A. The Virginia Hot Springs, Virginia. Average of six springs, analyzed by F. W. Clarke, Bull. U. S. Geol. Survey No. 9, 1884, p. 33. B. The Life well, Fairhaven Springs, Missouri. Analysis by P. Schweitzer, Geol. Survey Missouri, vol. 3, 892, p. 174. C. Deep well, Macomb, Illinois. Analyzed by G. Steiger in the laboratory of the United States Geological Survey. D. Cleopatra Spring, Yellowstone National Park. Analysis by F. A. Gooch and J. E. Whitfield, Bull. U. S. Geol. Survey No. 47, 1888, p. 36. Free C0 2 , 354 parts per million. E. Orange Spring, Yellowstone National Park. Analysis by Gooch and Whitfield, op. cit.,p. 38. Free C0 2 , 92 parts per million. F. Konigsquelle, Bad Elster, Saxony. Analysis by R. Flechsig, cited by A. Goldberg, 15. Ber. Naturw. Gesell. Chemnitz, 1904, pp. 74, 108. This memoir is a monograph on the mineral waters of Saxony and contains many analyses. Bicarbonates reduced to normal salts. Free C0 2 is also present. G. The Sprudel, Carlsbad, Bohemia. Analysis by F. Ragsky , cited by Roth, Allgemeine und chemische Geologie, vol. 1, p. 569. Contains 0.7604 gram free and half-combined C0 2 per kilogram. Also traces of Br, I, Li, B, Rb, and Cs. H. Chalybeate water, Mittagong, New South Wales. Analysis by J. C. H. Mingaye, Proc. Roy. Soc. New South Wales, vol. 26, 1892, p. 73. A very unusual water. In the same memoir, Mingaye gives many other analyses of Australian spring, artesian, and well waters. A B C D E F G H Cl 0. 64 0. 06 18. 02 10.09 10. 07 20. 36 11.52 27. 34 Br Trace. Trace. F . 03 S0 4 21. 73 51. 54 33. 22 30.34 32. 80 31. 47 31. 19 C0 3 40. 02 16. 84 13. 14 21. 65 20. 76 10. 96 19. 15 30. 58 P(L .01 As0 4 .26 B/) 7 1. 46 Undet. Na 1. 81 5. 33 26. 88 7. 50 7. 65 32. 51 32.49 7. 13 K 2. 04 .79 2. 95 3. 78 .45 1.35 8. 96 Li . 13 .10 .23 nh 4 . 03 Ca 23. 35 16. 86 5. 26 17. 76 17. 50 1.40 2. 23 4. 25 Sr . 01 Mg 5. 82 6. 39 2. 23 4. 21 4. 09 .44 . 65 5. 89 Mn . 19 . 01 Fe .79 .59 .02 15. 85 Fe 9 0q .07 A1 Trace. A1 2 0 3 . 58 . 04 . 54 . 13 Si0 2 4. 01 2. 19 .35 2. 98 3. 12 1. 40 1. 34 Salinity, parts per million 100. 00 563 100. 00 1, 670 100. 00 3, 008 100. 00 1, 732 100. 00 1, 612 100. 00 4, 991 100. 00 5, 431 •100. 00 225 97270°— Bull. 616—16 13 194 THE DATA OP GEOCHEMISTRY. SILICEOUS WATERS. Waters characterized by a large relative proportion of silica are common, and a number of examples were noted among river waters, Uruguay River forming an extreme case. Springs issuing from feldspathic rocks are likely to contain silica as a chief inorganic con- stituent, but the absolute amount of it is generally small. In volcanic waters, on the other band, and especially in geyser waters, the silica may reach half a gram to the liter, and sometimes even more. 1 It is usually reported as Si0 2 ; although in some cases, when the ordinary acid radicles are insufficient to satisfy the bases, it becomes necessary to assume the existence of silicates, even if their precise nature is unknown. For such waters it is convenient to report this saline silica in the form of the metasilicic radicle Si0 3 , the dried residue being supposed to contain the sodium salt Na 2 Si0 3 ; but this is hardly more than a convenient device for evading a recognized uncertainty. In solution, according to L. Kahlenberg and A. T. Lincoln, 2 sodium metasilicate is hydrolyzed into colloidal silica and sodium hydroxide; and this conclusion was also reached by F. Kohlrausch 3 about five years earlier, although he stated it in a more tentative form. In natural waters, then, silica is actually present in the colloidal state, and not in acid ions. On evaporation to dryness the silicate may form, but only when there is a deficiency of other acid groups. Such a deficiency is indicated by a pronounced alkalinity in any highly siliceous water. For convenience the silicic waters are divided below into two groups — first, two waters are given which are probably not of volcanic origin; second, a number of geyser waters appear in a table by them- selves. The first two waters are rather dilute. 1 For example, the Opal Spring, in the Yellowstone National Park, carries 0.7620 gram of silica per kilo- gram of water. The analyses of the Yellowstone Park waters, originally published in U.S. Geol. Survey Bull. No. 47, are also reprinted in Water-Supply Paper No. 364. 2 Join. Phys. Chem., vol. 2, 1898, p. 77. 3 Zeitschr. physikal. Chemie, vol. 12, 1893, p. 773. MINERAL WELLS AND SPRINGS. 195 Analyses of silicic waters of nonvolcanic origin. A. Big Iron Spring, Hot Springs of Arkansas. Analysis by J. K. Haywood, Rept. to U. S. Dept. Interior, 1902. This is & typical water, selected from among the 46 springs which were analyzed. All the hot springs in this group are very much alike. Haywood reports his carbonates wholly as bicarbonates, and his figures are here restated in normal form — that is, HC0 3 has been recalculated into the proper quan- tity of C0 3 corresponding to the normal salts. B. Cascade Spring, Olette, eastern Pyrenees. One of six analyses by E. Willm, Compt. Rend., vol. 104, 1887, p. 1178. Temperature, 79.4° C. In this water, which might also be classed as a sulphur water, the radicle Sa0 3 represents the presence of thiosulphates, produced by the partial oxidation of sulphides. Thiosulphates have also been reported in other waters, and several examples from Indiana are cited in Twenty-sixth Ann. Rept. Indiana Dept. Geology, 1901, pp. 76, 81, 86. A B Cl 1. 27 4. 38 Br I Traces. S0 4 3. 93 7. 28 S„0, 4. 81 s 3. 38 co 3 41. 47 12. 14 NO, .23 P0 4 .03 bo 2 . 64 Na 2. 38 26. 09 K . 80 2. 00 Li Trace. nh 4 . 03 Ca 23. 54 i.oi Ba, Sr Traces. Mr 2. 56 Trace. Mn . 17 Fe, A1 . 10 Si0 2 22. 85 38. 91 Salinity, parts per million 100. 00 a 199 100. 00 244 J ) Jr Ir a 284.8 in the original, where bicarbonates are included. In that statement HC0 3 forms 59.02 per cent of the total solids. This water might be equally well classed with the carbonate waters. For geyser waters and waters of similar character the data are abundant and only a few examples need be utilized here. 196 THE DATA OF GEOCHEMISTRY, Analyses of siliceous geyser waters. C. Coral Spring, Norris Basin, Yellowstone National Park. D. Echinus Spring, Norris Basin. E. Bench Spring, Upper Geyser Basin, Yellowstone National Park. F. Old Faithful Geyser, Upper Geyser Basin. G. Excelsior Geyser, Midway Basin, Yellowstone National Park. Analyses C to G by F. A. Gooch and J. E. Whitfield, Bull. U. S. Geol. Survey No. 47, 1888. A number of other geyser waters were ana- lyzed and are reported in this memoir. The figures given here vary somewhat from the original state- ments, having been recalculated on a different basis. The discrepancies, however, are very slight. H. Great Geyser, Iceland. Analysis by Sandberger, Ann. Chem. Pharm., vol. 62, 1847, p. 49. I. Te Tarata, Rotorua, New Zealand. The water which formed the white terrace of Rotomahana. A large excess of silica over bases, represented as Si0 3 . J. Otukapuarangi, Rotorua geysers. The water of the pink terrace. Excess of silica very small. Anal- yses I and J by W. Skey, Trans. New Zealand Inst., vol. 10, 1877, p. 423. Thirteen other analyses are given in this memoir. J. S. Maclaurin, in Thirty-ninth Ann. Rept. Colonial Laboratory, Mines Dept., New Zealand, gives 23 analyses of mineral springs in New Zealand. Several of them are very high in silica. See also the Forty-second Report. For early analyses of Yellowstone waters see H. Leffman, Am. Jour. Sci., 3d ser., vol. 25, pp. 104, 351. Analyses of several Icelandic geyser waters are given by A. Damour in Annales chim. phys., 3d ser., vol. 19, 1847, p. 470. C D E F G H I J Cl 36. 61 14. 93 Trace. 31. 64 20. 91 13. 52 26. 82 37. 52 Br Trace. .25 Trace. S0 4 1. 84 28. 65 29. 22 1. 30 1. 31 9. 01 3. 60 4. 96 s . 32 COo . 15 8. 78 25. 01 10. 16 P0 4 None. Trace. Trace. As0 4 . 08 . 29 . 24 . 29 B 4 0 7 2. 24 2. 38 1. 19 1. 34 Na 21.44 15. 65 12. 15 26. 42 31. 34 19. 71 33. 94 24. 22 K 4. 45 4. 89 2. 05 1. 93 2. 43 1. 88 1. 01 .36 Li .22 Trace. Trace. .40 . 15 Trace. nh 4 . 02 . 13 Trace. Trace. .28 Ca .39 1. 42 Trace. . 11 . 17 . 38 2. 59 Mg .08 None. Trace. . 04 . 17 .08 .09 .19 Mn Trace. Trace. Fe Trace. None. Trace. .13 FeoCL | 5. 80 . 20 Trace. A1 2 O s .76 .12 .17 .01 .35 Al. . 33 Si0 2 31. 72 31. 33 50. 78 27. 58 16. 58 45.04 29. 81 Si0 3 33. 95 Salinity, parts per million 100. 00 1,830 100. 00 808 100. 00 473 100. 00 1,388 100. 00 1,336 100. 00 1, 131 100. 00 2, 064 100. 00 2, 735 NITRATE, PHOSPHATE, AND BORATE WATERS. Although waters containing small quantities of nitrates, borates, or phosphates are not uncommon, waters in which these compounds are conspicuous are rare. Melville’s analysis of Steamboat Springs has already been cited, and the salts from that water contain nearly 9 per cent of the radicle B 4 0 7 , corresponding to about 11.5 per cent of anhydrous borax. 1 Nitrates are usually regarded as evidence of i Boric acid in natural waters has been discussed by L. Dieulafait in Compt. Rend., vol. 93, 1881, p. 224; vol. 94, 1882, p. 1352; and vol. 100, 1885, pp. 1017, 1240. According to L. Kahlenberg and O. Schreiner (Zeitschr. physikal. Chemie, vol. 20, 1896, p. 547), the group B 4 O 7 is not the true ion of the borates. It is a convenient expression, however, for the negative radicle of borax. MINERAL WELLS AND SPRINGS. 197 pollution in waters, but they do not necessarily indicate pollution. In arid regions, where nitrification goes on rapidly, nitrates may occur in considerable amounts; some of the underground waters of Arizona contain as high as 160 parts per million of nitrogen in this form.® The following analyses probably represent extreme examples of phosphates, borates, and nitrates in natural waters : * 6 Analyses of nitrate , phosphate , and borate waters. A. Hot spring from sulphur hank on the margin of Clear Lake, California. Analysis by G. E. Moore, Geol. Survey California, Geology, 1865, p. 99. In the original the carbonates are given as bicarbonates, and ammonium bicarbonate is reported to the extent of 107.76 grains per gallon. So great a proportion of ammonium in a water is extraordinary, although one acid water, cited later (p. 199), surpasses it. In the tabulation the bicarbonates are reduced to normal salts. B. Hot water from the Hermann shaft, Sulphur Bank, California. C. Hot water from the Parrott shaft, Sulphur Bank. Analyses B and C by W. H. Melville, cited by G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, p. 259. Some organic matter, a little H 2 S, and a con- siderable amount of C0 2 are reported in these waters. D. Phosphatic water from Viry, Seine-et-Oise, France. Analysis by Bourgoin and Chastaing; abstract in Jour. Chem. Soc., vol. 54, 1888, p. 354. The water issues from a gallery cut in clay. Bicarbonates reduced to normal salts. E. Spring “ Valette, ” at Cransac, Aveyron, France. One of nine analyses by A. Carnot, Compt. Rend., vol. Ill, 1890, p. 192. These springs issue below beds of coal and carbonaceous schists, in which fires have occurred. The nitrates were derived from the oxidation of the nitrogen compounds contained in the coal. F. The holy well Zem-Zem, at Mecca. Analysis by P. Van Romburgh, Rec. trav. chim., vol. 5, 1886, p. 265. For a corroborative analysis see M. Greshoff, idem, vol. 16, 1897, p. 354. The nitrates of this water are commonly ascribed to pollution by human agency; but it is not certain that so large a quantity, absolute or relative, could be derived from that source. Cl... I.... so 4 .. co 3 .. no 3 .. b 4 o 7 . P0 4 .. Na... K... Li... NH 4 . Ca... Mn.. Fe". Fe" 7 . A1 2 0 3 Si0 9 . Salinity, parts per million. 16. 49 .03 Trace. 21. 96 25. 61 24. 99 Trace. 7. 88 Trace. Trace. .40 2. 64 100. 00 c 5, 343 13. 57 .32 22. 38 27. 98 33. 97 .48 .05 .41 .11 .73 100. 00 5, 096 14. 39 10. 06 4. 73 40. 09 28. 49 .84 .02 .44 .03 .01 .90 100. 00 4, 632 5. 11 7. 74 19. 4§ 6. 33 22.41 3. 32 Trace. Trace. 30. 38 1. 21 4. 04 100. 00 490 5. 45 27. 87 2. 58 36. 09 3. 53 .68 Trace. 15. 93 5. 17 .06 .06 2." 58 100. 00 1, 163 16. 44 14. 04 12. 78 24. 62 12. 66 6. 67 8. 70 2. 70 1. 39 ] 00 . 00 3,455 a See W. W. Skinner, Bull. Arizona Exper. Sta. No. 46, 1903. 6 The mineral water of Cherrydale, Virginia, is also reported to be rich in nitrates. See analysis by J. K. Haywood and B. H. Smith, of a commercial bottled sample, in Bull. Bur. Chemistry No. 91, U. S. Dept. Agr., 1905, p. 54. Several springs in Massachusetts, reported by W. W. Skinner (Bull. Bur. Chemistry No. 139, 1911), are also remarkably high in nitrates, c Reckoned with normal carbonates. With bicarbonates the salinity becomes 6,556 parts per million. 198 THE DATA OF GEOCHEMISTRY. ACID WATERS. The last group of waters that we have to consider are those which contain free acids, sulphuric or hydrochloric. They may be classi- fied in two divisions — first, acid waters derived from sedimentary rocks, their acidity being probably due to the oxidation of pyrites or other sulphides; second, waters of volcanic origin. Under the first heading the four analyses given below may be cited. In these anal- yses it seems best to state the free acids as such and not in the form of ions, and to give, instead of the normal “salinity,” the total inorganic impurity in parts per million. Analyses of acid waters from sedimentary rocks. A. The Tuscarora sour spring, 9 miles south of Brantford,. Canada. Analysis by T. Sterry Hunt, Geol. Survey Canada, 1863, p. 545. B. Oak Orchard Spring, Alabama, Genesee County, New York. Analysis by W. J. Craw, Am. Jour. Sci., 2d ser., vol. 9, 1850, p. 449. The free acid is stated in the original as S0 3 ; it is here recalculated into H 2 S0 4 . C. Spring 9 miles northwest of Jonesville, Lee County, Virginia. Analysis by L. E. Smoot, Am. Chem. Jour., vol. 19, 1897, p. 234. Acidity low. D. Rockbridge Alum Spring, Virginia. Analysis by M. B. Hardin, Am. Chemist, vol. 4, 1873-74, p. 247. This water and that analyzed by Smoot might be equally well put in the ordinary sulphate group with other “alum” springs. A B C D H0SO4 free 69. 62 47. 87 5. 82 9. 37 HN0 3 free .18 Trace. Cl .43 .32 S0 4 , combined PCL 22. 11 Trace. 36. 28 75. 14 68. 21 Trace. Na . 26 . 87 1. 19 .22 K : .44 .71 .11 Li .01 Ca 3. 70 6. 39 .38 Ms . 50 2. 06 1. 11 Fe" 2. 17 3. 06 1. 19 Ye'" 2. 24 Mn .69 Ni .07 Co .05 Zn .08 Cu Trace. A1 1. 20 1. 00 12. 55 11. 08 Si0 2 1. 33 2. 88 7. 11 Total inorganic impurity, parts per million 100. 00 6, 161 100. 00 a 5, 136 100. 00 3, 715 100. 00 464 a 4,685 when the free acid is reckoned as S0 3 . Among volcanic waters acidity is much more common, and many examples of it are known. The following analyses are among the most typical, and are stated in the normal percentage form: MINERAL WELLS AND SPRINGS. 199 Analyses of add waters of volcanic origin. A. Devils Inkpot, Yellowstone National Park. Analysis by F. A. Gooch and J. E. Whitfield, Bull. U. S. Geol. Survey No. 47 .1888, p. 80. Acidity slight. This water is unique on account of its high pro- portion of ammonium salts. It contains NH 4 equivalent to 2.8 grams of ammonium sulphate per liter, or about 83 per cent of the total impurity. Contains also 65 parts of free C0 2 and 5 parts of H 2 S per million. As an ammoniacal water this may be compared with the borate water from Clear Lake, California, pre- viously cited. B. Acid Spring, California Geysers, Sonoma County, California. Temperature 60° C. Analysis by Thomas Price, Trans. Technical Soc. Pacific Coast, vol. 5, 1888, p. 48. Eleven analyses of other waters from this group of springs are also given. C. Water from Cove Creek sulphur beds, Utah. Recalculated from the analysis by W. M. Barr, as pub- lished by W. T. Lee in Bull. U. S. Geol. Survey No. 315, 1907, p. 489. The water issues from rhyolitic tuffs, but may not be of strictly volcanic origin. D. Rio Vinagre, Colombia. Analysis by J. B. Boussingault, Annales chim. phys., 5th ser., vol. 2, 1874, p. 80. Free SO3 recalculated into H2SO4. Boussingault also gives analyses of several saline waters from the same region. On p. 81 he estimates that Rio Vinagre at Purace carries each day 46,873 kilograms of H2SO4 and 42,150 kilograms of HC 1 . These figures correspond to 17,000 and 15,000 metric tons per annum. E. Hot Spring, Paramo de Ruiz, Colombia. Analyses by H. Lewy, cited by Boussingault, op. cit., p. 91. Free SO3 recalculated into H 2 S0 4 . F. Solfatara at Pozzuoli, Italy. Analysis by S. De Luca, Compt. Rend., vol. 70, 1870, p. 408. G. Brook finngi Pait, from crater of Idjen volcano, Java. Analysis by F. A. Fluckiger, Jahresb. Chemie, 1862, p. 820. Acid waters are not uncommon in Java. A B c D E F G HG1 free 0. 18 35. 92 5. 50 43. 96 H 2 S0 4 free 1.29 49. 71 31.38 1.89 44. 17 16. 62 HoBO, 2. 73 Cl .81 4. 75 4. 96 .34 14. 95 so 4 67. 66 33. 92 46. 95 43. 97 31. 71 55. 08 26. 96 s . 04 NO, . 02 Na . 73 .58 1. 47 3.08 3.22 Trace. 1. 32 K .24 .10 .57 .39 Li . 01 nh 4 22. 85 . 58 Ca 1. 18 .41 1. 62 2.45 1.21 2. 91 2. 05 Ms .36 5. 72 2. 48 2.31 . 55 .94 Mn Trace. Fe" Trace. 1.92 5. 74 1. 53 3.47 Fe"' 8.22 4. 66 A1 .10 1.02 None. 7. 14 3. 18 7. 16 4. 44 As Trace. Si0 2 2. 67 6. 62 1.27 .80 2. 21 12. 72 .33 Total impurity, parts per million 100. 00 3, 365 100. 00 5, 467 100. 00 9, 760 100. 00 2, 969 100. 00 8, 296 100. 00 2, 477 100. 00 18, 060 200 THE DATA OF GEOCHEMISTRY. Analyses of acid waters of volcanic origin — Continued. H. Hot Lake, White Island, Bay of Plenty, New Zealand. Analysis by C. Du Ponteil, Arm , Chem. Pharm., vol. 96, 1855, p. 193. Practically a 10 per cent solution of hydrochloric acid. I. Probably the same water as that of H. Analysis by W. Skey, Trans. New Zealand Inst., vol. 10, 1877, p. 423. In a later analysis by J. S. Haclaurin (Proc. Chem. Soc., vol. 27, 1911, p. 10), the presence of pentathionic acid is reported. J. Cameron’s Bath, Rotorua geyser district, New Zealand. Analysis by Skey, loc. cit. Contains 6 parts per million of H 2 S. K. Yellow lake or hot pool, crater of Taal volcano, Luzon, Philippine Islands. L. Green lake or pool, crater of Taal volcano. Analyses K and L by J. Centeno, Estudio geologico del volcan de Taal, Madrid, 1885. Obscurely stated. Recalculated on the assumption that “fosfato sodico” means Na 3 P 0 4 , and that sulphuric acid means H 2 SO 4 and not S0 3 . The free acid, however, should prob- ably be all hydrochloric, with no sulphuric at all. In this matter I have simply followed the author. Com- pare citation by G. F. Becker, Twenty-first Ann. Rept. TJ. S. Geol. Survey, pt. 3, 1901, p. 49. For recent analyses of these Taal waters, see R. F. Bacon, Philippine Jour. Sci., vol. 1, 1906, p. 433; vol. 2, 1907, p. 115. Unfortunately, these analyses, which corroborate Centeno’s, are stated in such form that I can not reduce them to the uniform standards. H I J K L HC1, free 65.42 69. 99 5. 60 13. 04 H 2 S0 4 free 59. 11 5. 87 2. 48 H 3 BO 3 Cl 11.69 9. 96 47. 26 44. 52 so 4 10. 64 11. 34 20 . 21 9. 50 6.40 P0 4 1. 91 Trace. 1.26 .73 B 4 0- Trace. Na.l . 75 1. 56 8 . 35 24. 14 20. 75 K . 59 .90 .32 1. 38 3.03 Ca 2. 30 . 50 .47 . 56 .22 Mr .34 .09 .22 .98 1.02 Mn Trace. Fe" 2 . 86 . 78 1. 03 Fe'" 5. 98 .33 5. 35 5. 55 A1 .35 2 . 62 Trace. .55 As Si0 9 .03 .18 5. 39 2.37 1. 23 Total impurity, parts per million 100 . 00 158, 051 100 . 00 194, 830 100 . 00 1 , 862 100 . 00 26, 989 100 . 00 60, 023 Still another acid water, from the crater of Popocatepetl, was partially analyzed by J. Lefort. 1 It contained 1 1 .009 grams of hydro- chloric acid and 3.643 of sulphuric acid in 1,000 parts, together with 2.080 grams of alumina, 0.699 of soda, and 0.081 of ferric oxide. Lime, magnesia, silica, and arsenic were present in traces. These data are too incomplete to admit of systematic discussion. The total dissolved matter amounted to 17,512 parts per million. J. B. Boussingault, 2 in his memoir on the acid waters of the Colom- bian Andes, discusses at some length the question of their origin. He shows that hydrochloric acid may he generated by the action of steam upon a mixture of chlorides and silica, and also that hot gas- eous hydrochloric acid will liberate sulphuric acid from sulphates. Both of these reactions may take place in volcanoes. Sulphuric acid 1 Compt. Rend., vol. 56, 1863, p. 909. 2 A Tin ales chim. pbys., 5th ser., vol. 2, 1874, p. 76. MINERAL WELLS AND SPRINGS. 201 may also be formed by volcanic heat, sulphur, either free or derived from sulphides, first burning to S0 2 , which afterward, in presence of moisture, oxidizes to H 2 S0 4 . It is also to be borne in mind that aqueous sulphuric acid will decompose chlorides, with liberation of HC1, and this reaction also probably occurs. The acidity of a vol- canic water, then, may be due to a variety of causes, which operate under varying conditions of material and temperature. We may not be able to say with certainty that a given water of this class origi- nated in a given way, but we can see that the reactions which pro- duce it are neither complex nor obscure. SUMMARY OF WATERS. From the evidence before us the classification of natural waters according to their negative or acid ions seems to be fully justified. This question has been partially discussed in previous chapters; but the greater variety of composition shown by mineral springs enables us now to cover the ground much more completely. The main divisions and subdivisions are as follows: I. Chloride waters. Principal negative ion Cl. A. Principal positive ion sodium. B. Principal positive ion calcium. C. Waters rich in magnesium. II. Sulphate waters. Principal negative ion S0 4 . A. Principal positive ion sodium. B. Principal positive ion calcium. C. Principal positive ion magnesium. D. Waters rich in iron or aluminum. E. Waters containing heavy metals, such as zinc. III. Sulphato-chloride waters, with S0 4 and Cl both abundant. IV. Carbonate waters. Principal negative ion C0 3 or HC0 3 . A. Principal positive ion sodium. B. Principal positive ion calcium. C. Chalybeate waters. V. Sulphato-carbonate waters. S0 4 and C0 3 both abundant. VI. Chloro-carbonate waters. Cl and C0 3 both abundant. VII. Triple waters, containing chlorides, sulphates, and carbonates in equally notable amounts. VIII. Siliceous waters. Rich in Si0 2 . IX. Borate waters. Principal negative radicle B 4 0 7 . X. Nitrate waters. Principal negative ion N0 3 . XI. Phosphate waters. Principal negative ion P0 4 . XII. Acid waters. Contain free acids. A. Acid chiefly sulphuric. B. Acid chiefly hydrochloric. This classification is sufficient for all practical purposes, although it might be subdivided still further in order to cover certain excep- tional cases, as, for example, the feebly acid ammonium sulphate water of the Devil’s Inkpot. Many waters are obviously interme- 202 THE DATA OF GEOCHEMISTRY. diate in character, like the brines containing both calcium and sodium, or the sulphates of two or more bases in something like equally important quantities. In a classification based on thera- peutic considerations sulphur waters would form a distinct group; but sulphides occur in subordinate amounts, and from a chemical point of view are merely incidental impurities. It has already been observed that mixtures can not be classified rigorously, a conclusion which it is well to reiterate now. The classification of natural waters is only approximate, and a matter of convenience rather than of fixed principles. CHANGES IN WATERS. When the water of a spring emerges into the open air it begins to undergo changes. It may flow into other waters and so lose its individuality; it may simply evaporate, leaving a saline residue; it may react upon adjacent material and so produce new substances; or, by cooling, it may deposit some one or more of its constituents. The first of these contingencies admits of no systematic discussion; the third will be considered in the next chapter; the others can receive attention now. Alteration by loss of gaseous contents is observed in two impor- tant groups — the sulphur waters and those containing an excess of carbonic acid. Hydrogen sulphide partly escapes into the atmos- phere without immediate change, and part of it is oxidized, with deposition of sulphur and the formation of thiosulphates and finally sulphates, which remain in solution. Deposits of finely divided sulphur are common around those springs which emit hydrogen sulphide, but they frequently contain other substances, such as silica, calcium carbonate, and ocherous matter. Since, however, the sulphur is a product of partial oxidation, this change comes more appropriately under the heading of reaction with adjacent material, the latter, in this case, being oxygen derived from the air. The hydrogen sulphide itself may be generated by the action of acid waters upon other sulphides, but it is more commonly produced by the reduction of sulphates through the agency of organic matter, and the subsequent decomposition of the resultant alkaline com- pounds by carbonic acid. The last reaction, however, as A. Bechamp 1 has shown, is reversible. Carbon dioxide decomposes solutions of calcium hydrosulphide; but, on the other hand, hydrogen sulphide can partly decompose solutions of calcium carbonate. Bicarbonates and sulphides, therefore, can coexist in mineral waters in a state of unstable equilibrium. i Annales chim. phys., 4th ser., vol. 16, 1869, p. 202. See also a recent physicochemical discussion by F. Auerbach, Zeitschr. physikal. Chemie, vol. 49, 1904, p. 217. MINERAL WELLS AND SPRINGS. 203 CALCAREOUS SINTER. With carbonated waters the changes due to escape of gas are more conspicuous, at least when calcium, magnesium, or iron happen to be the important basic ions. When the “bicarbonic” ion HC0 3 breaks up, losing carbon dioxide to the atmosphere, the normal calcium or magnesium carbonate is formed and, being insoluble, is precipitated. If we assume calcium bicarbonate as existent in solution, the reaction is as follows : CaH 2 C 2 0 6 = CaC0 3 + H 2 0 + C0 2 ; but the change is modified by other substances which may be present, and so the product is rarely pure, nor is the precipitation absolutely complete. Calcareous sinter, tufa, or travertine is thus produced, and in many localities it is an important deposit. The carbonate waters of the Yellowstone Park, for example, form large bodies of this character, and many analyses of it have been made. It is also abundant in the Lahontan and Bonneville basins, as mentioned in the preceding chapter. The following analyses of typical American material are sufficient to show its usual composition: Analyses of calcareous sinters. A. Travertine, Terrace Mountain, Mammoth Hot Springs, Yellowstone National Park. Analysis by E. A. Gooch, Bull. U. S. Geol. Survey No. 228, 1904, p. 323. B. Travertine, near Pulsating Geyser, Mammoth Hot Springs. Analysis by J. E. Whitfield, Bull. TJ. S. Geol. Survey No. 228, 1904, p. 323. Other analyses of calcareous deposits are given in the same publi- cation. See also W. H. Weed, Ninth Ann. Kept. U. S. Geol. Survey, 1889, p. 619. C. Lithoid tufa, Lahontan basin, Nevada. One of three analyses by O. D. Allen, cited by I. C. Russell, Mon. U. S. Geol. Survey, vol. 11, 1885, p. 203. D. Calcareous tufa, main terrace, Redding Spring, Great Salt Lake Desert. Analysis by R. W. Wood- ward, Rept. U. S. Geol. Expl. 40th Par., vol. 1, 1878, p. 502. A B C D Insoluble ! 1. 70 Si0 2 0. 09 } - 11 55. 37 .35 .04 0. 05 } - 11 52. 46 .90 .71 .33 8. 40 1. 31 Trace. 46. 38 3. 54 .22 .48 Trace. ai 2 0 3 Fe 2 0 3 CaO } .25 50. 48 2. 88 MgO k 2 o Na 2 0 Li 2 0 NaCl .10 1. 45 Cl Trace. Trace. 41.85 .30 2. 07 S0 3 .44 43. 11 1. 82 40. 88 C0 2 PXb 38. 20 Trace. 1. 71 ±2Y5 h 2 o .32 .17 1. 02 .30 C, organic 100. 10 100. 03 99. 53 100. 24 204 THE DATA OE GEOCHEMISTEY. Analyses of several European tufas are given by Roth, 1 and they exhibit many variations in composition. Ten calcareous deposits from the springs of Vichy were analyzed by J. Bouquet, 2 who found strontium and arsenic in them. The arsenic ranged from a trace to 1.16 per cent of As 2 0 5 . In the Carlsbad “Sprudelstein” Blum and Leddin 3 also found arsenic to the extent of 0.27 per cent. In a tufa from the Doughty Springs, in Delta County, Colorado, W. P. Head- den 4 found barium sulphate ranging from a small amount up to nearly 95 per cent. This tufa or sinter was distinctly radioactive, and probably contained traces of radium. The commonest companion of calcium carbonate in sinter is mag- nesium carbonate, which is rarely, if ever, absent. According to H. Leitmeier 5 the springs of Lohitsch in Styria deposit hydrous car- bonate of magnesium. The presence of magnesium salts in a water favors the deposition of calcium carbonate in the form of aragonite, as shown by F. Cornu 6 and F. Vetter. 7 Calcite, however, is much more common in sinters than aragonite. In rare instances fluorite is deposited. 8 Silica and ferric hydroxide are also frequent con- taminations of tufas. In short, the calcium carbonate precipitated from natural waters may carry down with it a great variety of impurities, which depend upon the character of the spring. OCHEROUS DEPOSITS. When ferrous ions are present in a carbonate water, loss of carbonic acid is followed or accompanied by oxidation, and the precipitated material is an ocherous ferric hydroxide. Around chalybeate springs these deposits of iron rust are always noticeable. With substances of this character calcium and magnesium carbonates are often thrown down, and also silica, so that the ochers from iron springs vary much in composition. Between an ocher and a calcareous sinter every intermediate mixture may occur. Sometimes when sulphates have been reduced by organic matter sulphides of iron are deposited, and v a number of examples of this kind are cited by Roth. 9 The following analyses will illustrate the usual character of these sediments. 1 Allgemeine und chemische Geologie, vol. 1, p. 539. 2 Annales chim. phys., 3d ser., vol. 42, 1854, p. 332. For later analyses of Vichy deposits, see C. Girard and F. Bordas, Compt. Rend., vol. 132, 1901, p. 1423. 3 Ann. Chem. Pharm., vol. 73, 1850, p. 217. 4 Proc. Colorado Sci. Soc., vol. 8, 1905, pp. 1-30. Analyses of six of the springs are given in this memoir, and several analyses of sinters. On the coexistence of barium and sulphates in mineral waters see P. Carles, Jour. Chem. Soc., vol. 80 (abstracts), pt. 2, 1901, p. 506. Alkaline bicarbonates, with an excess of CO 2 , can hold barium in solution, notwithstanding the presence of sulphates. R. Delkeskamp, in Notizbl. Ver. Erdkunde, 4th ser., Heft 21, p. 47, has discussed the occurrence of barium in natural waters and tabulated a large number of occurrences. See also J. White, Jahresb. Chemie, 1899, p. 635, on barium in artesian waters of Derbyshire. 5 Zeitschr. Kryst. Min., vol. 47, 1909, p. 104. 6 Oesterr. Zeitschr. Berg- u. Hiittenw., vol. 55, 1907, p. 596. 7 Zeitschr. Kryst. Min., vol. 48, 1910, p. 45. 8 See W. Lindgren, Econ. Geology, vol. 5, 1910, p. 22. sAllgemeine und chemische Geologie, vol. 1, pp. 599, 600. MINERAL WELLS AND SPRINGS. 205 Analyses of ocherous deposits. A. Deposit from Driburg, Germany. Analysis by F. J. H. Ludwig, Jahresb. Chemie, 1847-48, p. 1012. B. Deposit from Nauheim, Germany. Analysis by Ewald, Jahresb. Chemie, 1847-48, p. 1012. C. Deposit from Enclos des Celestins, Vichy. One of four analyses by J. Bouquet, Annales chim. phys., 3d ser., vol. 42, 1854, p. 336. The “quartz and mica,” of course, do not belong with the sediment, but are an accidental addition to it. D. Deposit from Chalybeate Spring, Death Gulch, Yellowstone National Park. Analysis by J. E. Whitfield in the laboratory of the United States Geological Survey. For an analysis of water from Death Gulch, see G. B. Frankforter, Jour. Am. Chem. Soc., vol. 28, 1906, p. 714. • A B 0 D Fe 2 0 3 57. 303 49. 86 47. 40 63. 03 Mn 2 0 3 .40 Trace. ALO, .08 CaO 6. 683 CaC0 3 20. 81 10. 85 MgCO, 6.03 NaCl, etc 2. 59 so 3 .543 8. 35 P 9 0- Trace. As 2 0 3 .063 AsoCL 6. 96 Soluble Si0 2 2.81 1. 04 } 25. 72 1. 37 H 2 0 23. 333 23.53 Organic matter . 542 1 26. 94 J Sand 5. 388 J Quartz and mica 2. 06 C0 2 and loss 6. 145 100. 000 100. 00 100. 06 99. 77 The deposit represented by analysis D evidently contains an admixture of a basic sulphate of iron. A number of such salts are known among natural minerals, and are commonly formed by deposi- tion from chalybeate solutions. Their consideration, however, does not belong in this chapter. Ocherous deposits rich in manganese are also known. For example, M. Weibull 1 has described a spring near Lund, in Sweden, which contains 23 milligrams of MnO to the liter of water. From this, by the action of the organism Crenothrix manganifera , the manganese oxide is precipitated in such quantities as to clog water pipes. SILICEOUS DEPOSITS. Siliceous deposits are formed by all waters containing silica, but are commonly so small as to be inconspicuous. The silica then ap- pears, as in the preceding tables of analyses, as an impurity in some- thing else. From hot springs, however, which often contain silica in large quantities, great bodies of sinter are produced, and this has a composition approaching that of opal. Miner alogically, siliceous sinter is classed as a variety of opal, for it consists mainly of 1 Jour. Chem. Soc., vol. 92, pt. 2, 1907, p. 888, abstract. 206 THE DATA OF GEOCHEMISTRY. hydrated silica with variable impurities. According to W. H. Weed , 1 who has studied the formation of sinters in the Yellowstone Park, the deposit may be due either to relief of pressure, to cooling, to chemical reactions between different waters, to simple evaporation, or to the action of algae. In the last case the silica forms a gelatinous layer upon the algous growths, and this, after the death of the algae, gradually hardens to sinter. The subjoined analyses (A to E) of Yellowstone Park sinters are selected from among fifteen which were made by J. E. Whitfield in the laboratory of the United States Geo- logical Survey . 2 Analyses of sinters from Yellowstone Parle, etc. A. Incrustation, Excelsior Geyser Basin. B. Opal deposit, Norris Basin. C. Compact sinter, Old Faithful Geyser. D. Deposit from Artemisia Geyser. E. Geyserite incrustation, Giant group. Upper Basin. F. Siliceous sinter, Steamboat Springs, Nevada. Analysis by R. W. Woodward, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 826. A B C D E F Si0 2 94.40 } _ .79 93. 60 89. 54 83. 10 72. 25 92. 67 A1 2 0 3 1. 06 2. 12 6. 02 10. 96 Fe 9 0q Trace. Trace. Trace. . 7j6 } . 80 FeO . .31 ) CaO None. . 50 1. 71 .80 .74 . 14 MgO None. Trace. Trace. .21 .10 .05 K 2 0 .30 . 87 1. 66 . 18 Na^O 1. 12 2. 18 3. 55 .75 NaCl Trace. .36 H 2 0 « C 5. 02 4. 71 5. 13 6. 73 9. 02 .20 5. 45 so 3 Trace. .28 .45 s Trace. 100. 21 99. 87 99. 92 100. 19 100. 36 100.04 a Loss on ignition. At Steamboat Springs G. F. Becker 3 found the deposits to contain also sulphides of antimony, arsenic, lead, copper, and mercury, ferric hydroxide, gold, silver, and traces of zinc, manganese, cobalt, and nickel. The following analyses represent sinters from foreign localities : 4 1 Am. Jour. Sci., 3d ser., vol. 37, 1889, p. 351. 2 Bull. U. S. Geol. Survey No. 228, 1904, pp. 298-299. A very exceptional sinter, from a warm spring in Selangor, Malay States, contains, with 91.8 per cent of Si02, 0.5 per cent of SnC> 2 . See S. Meunier, Compt. Rend., vol. 110, 1890, p. 1083. According to W. R. Jones (Geol. Mag., 1914, p. 537), the water of this spring contains no tin. 3 Mon. U. S. Geol. Survey, vol. 13, 1888, pp. 343-346. 4 For additional analyses see Roth, Allgemeine und chemische Geologie, vol. 1, p. 593. MINERAL WELLS AND SPRINGS. 207 Analyses of sinters from foreign localities. G. Geyserite, Iceland. Analysis by A. A. Damour, Bull. Soc. gdol. France, 2d ser., vol. 5, 1847-48, p. 160. H. Deposits from the Scribla spring, Icelandic geysers. Analysis by C. Bickell, Ann. Chem. Pharm., vol. 70, 1849, p. 293. I. Sinter from the hot springs of Taupo, New Zealand. Analysis by J. W. Mallet, Philos. Mag., 4th ser., vol. 5, 1853, p. 285. J. Sinter from geysers of Rotorua, New Zealand. Analysis by J. E. Whitfield, discussed by W. H. Weed, Ninth Ann. Rept. U. S. Geol. Survey, 1889, p. 619. Two other analyses are given in this report. K. Sinter from the Mount Morgan gold mine, Queensland. Analysis by E. A. Schneider, discussed by W. H. Weed in Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 166. This sinter is impregnated with auriferous hematite. In sinters from the geyser district of New Zealand, according to J. M. Maclaren (Geol. Mag., 1906, p. 511), there are also appreciable quantities of gold and silver. G H I j K SiOo 87. 67 } - 71 88. 26 94. 20 92. 47 94. 02 } 2.27 ALOq . 69 1. 58 2. 54 F e 2 0 3 3. 26 .17 MgO Trace. . 15 Trace. CaO . 40 . 29 Trace. .79 .07 K 2 0 Trace. . 11 Na 2 0 .82 .11 NaCl .85 H 2 0 so, 10. 40 4. 79 2. 49 3. 06 3. 99 3. 36 100. 00 100. 00 99. 86 99. 94 99. 72 The sinters, however, represent only the simplest form of deposit from geysers and siliceous springs. A great variety of intermediate substances, mixtures of silica, of hydroxides, of carbonates, sulphates, or arsenates, and even of sulphur, have been observed, and a number of analyses made in the laboratory of the United States Geological Survey by J. E. Whitfield are cited below as illustrations of this fact. All the samples analyzed were collected in the Yellowstone National Park. 208 THE DATA OF GEOCHEMISTRY. Analyses of spring deposits from Yellowstone Parle. A. Deposit from spring No. 75, Norris Basin. Dried at 104°. B. Saline deposit, Shoshone Geysers. Dried at 104°. C. Sediment from Crater Hill. D. Black coating, Fairy Springs. Air dried. E. Deposit from Chrome Spring, Crater Hill. F. Sedimentary deposit from Lamar River. G. Deposit from Constant Geyser. Described by Arnold Hague in Am. Jour. Sci., 3d ser., vol. 34, 1887, p. 171. Contains scorodite. H. Red, ocherous deposit, Arsenic Geyser. Air dried. A B C D E F G H Si0 2 54. 36 50. 03 54. 12 21. 36 68. 73 } 3.66 29. 23 49. 83 41. 20 ALO, 5. 90 2. 15 18. 03 3. 11 Trace. 4. 74 9. 53 FeoO, 25. 48 Trace. .86 9. 17 1. 91 18. 00 19. 35 MnO .33 6. 19 Mn0 2 38. 65 MgO . 17 Trace. Trace. . 82 .29 .07 CaO 1. 86 Trace. .32 7. 50 2. 14 .50 Na^jO 1. 30 24. 18 .49 K 2 0 1. 21 . 32 3. 82 Li 2 0 None. . 24 H 2 0 9. 60 4. 78 7. 12 13. 02 6. 15 3. 03 10. 62 15. 70 COo 12. 92 S0 3 ' 5. 40 15. 41 .09 .24 s 18. 79 64. 29 As 2 0 5 .28 None. 17. 37 14. 08 C, organic 1. 04 100. 49 100. 02 100. 27 99. 91 99. 76 100. 07 100. 56 100. 10 Analyses Gr and H are especially interesting, for they represent the deposition of scorodite, FeAs0 4 .2H 2 0. This occurs still more per- fectly at Josephs Coat Springs, in the Yellowstone Park, where the mineral has been separated from an incrustation and identified. 1 The manganese in D and the sulphur in E and F are also worthy of notice. When we consider that in addition to these precipitates many saline compounds are produced by the simple evaporation of waters, we see that the range of possibilities must be very great. When a water has become sufficiently concentrated to begin the deposition of solid matter, every change in concentration or temper- ature introduces a new set of conditions which determine the nature of the compounds to be formed. The complexity of the problems which thus originate will become more evident when we study the subject of saline residues. It is clear, from the nature of the prod- ucts thus far considered, that in a complex water several reactions may take place simultaneously, a number of substances being thrown down at the same time. If a water carrying much iron and much calcium loses hydrogen sulphide and carbonic acid, then ferric hydroxide, calcium carbonate, and sulphur will be deposited i A. Hague, Am. Jour. Sci., 3d ser., vol. 34, 1887, p. 171. See also J. E. Whitfield, Bull. U. S. Geol. Sur- vey No. 55, 18S9, p. 65. MINERAL WELLS AND SPRINGS. 209 together, each change being independent of the others. In such cases the complexity of reaction is apparent only and not real. The reactions are all simple and easily understood. When salts are formed by evaporation of a water, the interpretation of the phenomena is more difficult. REACTIONS WITH ADJACENT MATERIAL. The reactions of natural waters in contact with adjacent materials are of many different kinds. We have already seen how oxygen from the atmosphere may convert ferrous into ferric compounds and sulphides into sulphates, but reducing agents also must be taken into account. The sulphates of a water, by accession of organic matter, can be partly or entirely reduced to sulphides, and carbonic acid, acting upon the latter, may expel sulphureted hydrogen and produce carbonates. By reactions of that kind a water can undergo a com- plete change of type and pass from one class into another. Acid waters, especially when hot, act vigorously on the substances with which they come in contact, producing soluble chlorides or sul- phates according to their character. Hydrochloric acid forms the one set of salts, sulphuric acid the other. The extent of the reactions will of course depend upon the kind of material attacked, for some minerals and rocks are much more soluble than others. The carbon- ate rocks are naturally the most attackable, but no rock is entirely exempt from changes of this order. When we remember that even pure and cold water exerts a solvent action upon many silicates, we can see how violently corrosive a hot, acid, volcanic water must be. Wherever waters of this class occur the surrounding rocks are more or less decomposed, calcium, magnesium, alkalies, and iron being dissolved out, while silica and hydrous aluminum silicates remain behind. As the water cools and as the acid becomes neutralized its activity decreases, and its peculiar characteristics gradually disappear. An ordinary saline or astringent water is the product of these changes, which take place most rapidly when the active solutions are concen- trated and hot and more slowly in proportion as they are diluted or cooled. Waters containing free sulphuric or hydrochloric acid are, however, relatively rare, and their geological importance is small compared with that of carbonated solutions. Meteoric waters carrying free carbonic acid are probably the most powerful of agents in the solution of rocks, although their chemical activity is neither violent nor rapid. Being continually replenished from the storehouse of the atmosphere, their work goes on unceasingly over a large portion of our globe. The calcium which they extract from rocks is carried by rivers to the sea and is finally deposited in the form of limestones. Springs and 97270°— Bull. 616—16 14 210 THE DATA OF GEOCHEMISTRY. underground waters charged with carbonic acid exert the same sol- vent action, but locally and in different degree. We have seen that many springs are so heavily loaded with carbonic acid that they effervesce when issuing into the air, and such waters are peculiarly potent in effecting the solution of limestones. By percolating waters of this class limestone caverns are made, and part of the substance dissolved is redeposited as stalactite or stalagmite. In reactions of this kind the general character of a water is not changed; it may be a calcium carbonate water throughout its course, varying only in gaseous content and in concentration, and its chemical effectiveness is shown by its work as a carrier in transporting from one point to another the material that it has dissolved . 1 Alkaline waters, especially thermal waters of the sodium carbonate class, are also active solvents of mineral substances. Their tendency, however, is opposite to that of the acid waters, for they dissolve silica rather than bases, and act as precipitants for magnesia and lime. When solutions of calcium sulphate and sodium carbonate are com- mingled, calcium carbonate is thrown down and an equivalent amount of sodium sulphate remains dissolved. Since natural waters are rarely, if ever, chemically equivalent, reactions of this sort between them are necessarily incomplete, and the blended solutions will con- tain one group of ions in excess over the other. Thus a water of mixed type is produced, but the mixture is not an average of the two solutions, for part of their original load has been removed. This is a simple case of reaction, but it may be complicated in various ways, and even reversed. For instance, a solution of sodium sul- phate in presence of free carbonic acid will dissolve calcium car- bonate, forming sodium bicarbonate and a precipitate of gypsum. E. W. Hilgard 2 has investigated this transformation, and regards it as the principal source of alkaline carbonate solutions in nature. Furthermore, mineral substances with which alkaline waters come in contact may be profoundly modified, as at the thermal springs of Plombieres in France. Here, according to Daubree , 3 the brickwork and masonry of the ancient Roman baths have been strongly attacked with the production of hyalite and a number of zeolitic minerals. Many mineral springs contain organic matter, presumably in the form of the so-called humus acids, but the influence exerted by these substances is more pronounced in swamp and river waters . 4 Their 1 On the magnitude of erosion by subterranean waters see H. Schardt, Bull. Soc. neuchateloise sci. nat., vol. 33, 1907, p. 168. 2 Am. Jour. Sci., 4th ser., vol. 2, 1896, p. 100. 3 Etudes synthetiques de geologie experimental, 1879, pp. 179 et seq. Other localities at which similar changes have been observed are also described. The Plombieres water is said to be a very dilute solution of alkaline silicates, but its exact composition is not given by Daubree. Analyses of six waters from Plom- bi&res can be found in Les eaux m morales de la France, by E. Jacquot and E. Willm, Paris, 1894, p. 224. They confirm Daubree ’s statement. 4 See Chapter III for details on this subject. Also A. A. Julien, Proc. Am. Assoc. Adv. Sci., vol. 28, 1879, p. 311. MINERAL WELLS AND SPRINGS. 211 supposed solvent action upon rocks and soils has already been noticed, as well as their alleged efficiency in retaining silica in solution. Against these suppositions I may cite an observation by C. A. Davis in the United States Geological Survey, that the peat of the Dismal Swamp contains the siliceous skeletons of diatoms whose outlines are still perfectly sharp, without the slightest trace of blurring. This observation has been confirmed by Chase Palmer. The water saturating the peat contains much dissolved organic matter, which colors it strongly brown, and also contains floating diatoms. Furthermore, iron and alumina may be removed from sulphate or chloride waters by the action of limestones. If the iron is in the ferrous state, it must first be oxidized to the ferric condition. Then, by means of calcium carbonate, both of the bases named can be pre- cipitated, either as hydroxides or as basic sulphates. Insoluble com- pounds of the latter class are often formed from natural waters, and many mineral species are of that character. It is quite probable that limestone is also effective in removing other heavy metals from their solutions; copper, for example, is certainly thrown down, but these reactions need to be more fully investigated. Their consideration must be deferred until we reach the subject of metalliferous deposits. Finally, the character of a water may be greatly changed by simple percolation through the soil. That potassium is thus removed from natural waters has long been known, and reference to this fact was made in a previous chapter. Experiments by J. T. Crawley and R. A. Duncan 1 on Hawaiian soils show that a layer 6 inches thick will fix over 98 per cent of the potassium in a solution of potassium sulphate which is allowed to filter through it, and the retention of phosphoric acid and ammonia is even more complete. According to J. M. van Bemmelen, 2 basic zeolitic silicates are the chief agents in effecting the retention of potassium, exchanging other bases for it by double decomposition, but the existence of such compounds in the soil is not well established. Hydrous aluminum silicates may be the effective absorbents, or, in the case of phosphoric acid, the hydroxides of aluminum and iron. After potassium and ammonium, Van Bem- melen finds that magnesium is most readily absorbed, then sodium, and calcium least of all. It is clear, however, that the nature of the soil must be taken into account. A sandy soil or an impervious clay would be less effective in removing saline substances from water than a loose loam rich in hydrous basic compounds. The fact that sub- stances are taken from waters by soils is certain, but the extent of the absorption depends upon local conditions. It is also certain that potassium, rather than sodium, is thus withdrawn from aqueous circulation. 1 Jour. Am. Chem. Soc., vol. 25, 1903, p. 47. See also vol. 24, 1902, p. 1114. 2 Landw. Versuchs-Stationen (Berlin), vol. 21, p. 135. 212 THE DATA OF GEOCHEMISTRY. A careful consideration of all the evidence concerning mineral springs will show that it is exceedingly difficult to generalize on rela- tions between the composition of a water and its geological history. Reactions which take place deep within the earth can not easily be traced, especially as a water may undergo various modifications before it reaches the surface. A spring may be a blend from different sources — either a direct mixture or a solution from which ingredients have been removed — and it is only in specific cases that a simple interpretation of the phenomena can be found. The water that rises from a salt bed or from gypsum is easily understood, and so also is one which carries sulphates derived from pyritiferous shales. The Hunyadi Janos water is obtained from wells sunk near a mass of pyritiferous dolomite, and therefore its high proportion of mag- nesium sulphate is readily intelligible. We can see that a water from granite must differ greatly from one issuing out of limestone, and Hanamann’s analyses of the Bohemian rivers illustrate this order of dissimilarity. Many regularities can be traced, but no general prin- ciple can be deduced from them. For example, A. De Lapparent 1 shows that solfataras are most common in regions of highly siliceous eruptive rocks, such as rhyolites, andesites, etc., a condition which he attributes to the inferior fluidity of the volcanic magmas and the consequently greater retention of gaseous contents by them. In areas of subsilicic rock solfataras rarely or never occur. Various attempts have been made to correlate the composition of waters with the geological horizons from which they flow. For spring waters such attempts are of little value, because two springs, side by side, may be widely different. In the case of artesian wells the problem is perhaps simpler, for there the horizon can be de- termined. Artesian waters of common origin often show a family likeness to one another, especially in their minor constituents, one group being always calciferous, another relatively rich in bromine, and so on . 2 But no law can be framed to cover even these regularities, for the exceptional waters are too numerous and too confusing. That waters from sedimentary rocks are, as a rule, more concentrated and perhaps more complex than those from the older crystalline forma- tions is doubtless true; but beyond that it is hardly safe to generalize. It is better to discuss each water by itself, and so seek to interpret its individual history. 1 Compt. Rend., vol. 108, 1889, p. 149. 2 A. C. Lane (Water-Supply Paper U. S. Geol. Survey No. 31, 1899) classifies the Michigan waters with reference to their origin, and points out various similarities connected with identity of horizon. On the chemical relations between spring waters and the rocks from which they issue, see M. Dittrich, Mitth. Badisch. geol. Landesanstalt, vol. 4, 1901, p. 199. MINERAL WELLS AND SPRINGS. 213 YADOSE AND JUVENILE WATERS . 1 Whether it is possible to discriminate between waters of superficial or vadose origin and magmatic or deep-seated waters is a question for geology to answer. Until quite recently the prevalent opinion has been that all spring waters, including those emitted by geysers, were originally meteoric. Modern investigations into volcanism and upon the subject of metalliferous veins have, however, led to a reopening of the question. E. Suess , 2 speaking with especial refer- ence to the thermal springs of Carlsbad, has advanced strong argu- ments to show that waters of this class are “ juvenile” and now see the light of day for the first time — that is, they issue from deep within the earth, from the fundamental magma itself, and bring up veritable additions to the hydrosphere. These magmatic waters, furthermore, are regarded by some authorities as the carriers of metallic salts, by which certain kinds of metalliferous veins have been filled . 3 This subdivision of springs into vadose, or those which represent original infiltrations of surface waters, and juvenile, as Suess terms them, has had wide but not universal acceptance. A difficulty in applying the proposed nomenclature arises from the fact that it is not easy to determine where a given water belongs. Armand Gautier , 4 however, has pointed out several criteria which may make discrimi- nation possible. He shows that vadose waters, or waters of infiltra- tion, are characterized by fluctuations in composition, concentra- tion, and rate of flow, depending upon local and variable conditions, such as abundant rain or drouth. They also contain, as a rule, carbonates of lime or magnesia, chlorides, and sulphates. Virgin or juvenile waters, on the contrary, are fairly constant in all essential particulars, and carry sodium bicarbonate, alkaline silicates, heavy metals, etc., as chief constituents, with chlorides or sulphates only as accessories, and practically no carbonates of the alkaline earths. The vadose waters, moreover, issue from faults having no relation to-, the metallic veins of the surrounding territory — a lack of relation, which is conspicuous as regards juvenile springs. Gautier holds 1 The term “connate” is also used to some extent to describe buried or fossil waters. The calcium chloride waters of the Lake Superior region have been assigned to this class. 2 In Verhandl. Gesell. Deutsch. Naturforscher und Arzte, 1902. Abstract in Geog. Jour., vol. 20, p. 520 1902. On the other hand, see E. H. L. Schwarz, Geol. Mag., 1904, p. 252; and J. M. Maclaren, idem, 1906, p. 511. These writers regard the hot waters of Africa and New Zealand as originally vadose. The same conclusion is reached by Arnold Hague relative to the geyser waters of the Yellowstone National Park. See Scribner’s Mag., May, 1904, p. 513, and Trans. Am. Inst. Min. Eng., vol. 16, 1887, p. 783; also his presi- dential address in Bull. Geol. Soc. America, vol. 22, 1911, p. 103, and Science, vol. 33, p. 555. 3 See for example, W. Lindgren, Eng. and Min. Jour., vol. 79, 1905, p. 460. Also A. C. Spencer, Trans. Am. Inst. Min. Eng., vol. 35, 1905, p. 473; vol. 36, 1906, p. 364. 4 Compt. Rend., vol. 150, 1910, p. 436. Other papers bearing on this subject, and on the origin of the carbon dioxide of mineral waters are by R. Delkeskamp, Zeitschr. gesammte Kohlensaure-Industrie, 1906, Nos. 18-21; L. De Launay, Annales des mines, 10th set., vol. 9, 1906, p. 5; F. Henrich, Zeitschr. prakt. Geologie, 1910, p. 85; and O. Stutzer, idem, p. 346. 214 THE DATA OF GEOCHEMISTRY. that hydrogen emitted from the hot interior of the earth acts as a reducing agent upon metallic oxides and so forms the magmatic water of the springs. With the water thus generated, other water, that of constitution from minerals like the micas, is commingled. THERMAL SPRINGS AND VOLCANISM. The work of Gautier just cited is intimately related to an earlier memoir, 1 in which the close connection between volcanism and the formation of thermal springs is shown. His work will be consid- ered more in detail in a later chapter, hut his general conclusions may be cited now. When a crystalline rock, like granite, is heated to redness in vacuo, water and gases, the latter identical in character with the volcanic gases, are given off. For instance, to cite the least significant example, 1 cubic kilometer of granite can yield from 25 to 30 millions of metric tons of water, which at 1,100° would form 160,000,000,000 cubic meters of steam. In addition to this enormous volume of vapor 28,000,000,000 cubic meters of other gases would be emitted. Suppose, now, that by fissuring and subsidence in the litho- sphere such a mass of rock were carried down to a depth of 25,000 to 30,000 meters. It would then be in the heated region, and the evolu- tion of vapors under great pressures would occur. To some such changes Gautier ascribes the phenomena of volcanism, with all its development of solfataras and fumaroles. Ordinary thermal springs may be formed by the same process, operating, perhaps, less violently, and originate, so to speak, from a sort of distillation of the combined water contained in the depressed masses of rock. In an earlier memoir 2 Gautier has shown that granite, heated with water in a sealed tube to a temperature between 250° and 300°, yields solutions containing sulphur compounds and resembling the sulphur waters of hot springs. This sulphur he ascribes, not to the decomposition of metallic sulphides, but to reactions upon sulphosilicates, a class of compounds represented in nature by hauynite and lazurite, 3 and also by certain artificial substances which Gautier himself has prepared. He also supposes that carbon oxysulphide, COS, may be formed in the terrestrial nucleus, possibly from carbon monoxide generated by reac- tions between oxides and metallic carbides. Here he enters the field of speculation, where it is not necessary for us to follow him. The reactions which he has experimentally established are sufficiently suggestive, and his broad general conclusions are entitled to the most respectful consideration. 1 Annales des mines, 10th ser., vol. 9, 1906, p. 316. A good abstract by F. L. Ransome is given in Econ. Geology, vol. 1, 1906, p. 688. 2 Compt. Rend., vol. 132, 1901, p. 740. 3 Helvite and danalite are other natural sulphosilicates which might easily take part in the supposed reactions. MINERAL WELLS AND SPRINGS. 215 And yet, notwithstanding all that has been written on the subject, the controversy over the genesis of hot springs is not closed. What is the origin of the carbon dioxide with which so many mineral waters are heavily charged? In some instances, doubtless, it is derived from the decomposition of limestones, but in others this expla- nation can not suffice. Here and there it may be, to use Suess’s expression, “juvenile,” and evidence of the deep-seated origin of a spring . 1 Again, whence comes the sodium chloride of waters that flow from sources where it could not have been previously laid down ? These questions and others like them still await satisfactory answers. With mere suppositions, however plausible they may seem, we can not be content. A word in conclusion on the radioactivity of spring waters. A very large number of such waters possess this property, but no distinction between vadose and juvenile waters can be based upon the observa- tions. Waters of both classes are radioactive, but the phenomenon is perhaps most common among waters of volcanic origin, or at least among thermal springs. In the United States the Hot Springs of Arkansas have been studied by B. B. Bolt wood . 2 The springs of Missouri 3 and the Yellowstone National Park 4 were investigated by H. Schlundt and B. B. Moore. In each of these researches radio- activity was generally detected, but with varying intensity within the same group of springs. On the radioactivity of European waters there is a copious literature. BIBLIOGRAPHIC NOTE. The following collections of water analyses will be found useful for reference : F. Raspe. Heilquellen-Analysen, Dresden, 1885. A very large collection of analyses, mainly of European mineral waters. T. E. Thorpe. Dictionary of applied chemistry, article “Water, ” vol. 3, pp. 952-959, 1893. Tables of analyses of European mineral springs. The same article gives much information about other waters. J. K. Crook. The mineral waters of the United States, New York and Philadelphia, 1899. A. C. Peale. The mineral springs of the United States: Bull. U. S. Geol. Survey No. 32, 1886. F. A. Gooch and J. E. Whitfield. Analyses of waters of the Yellowstone National Park: Bull. U. S. Geol. Survey No. 47, 1888. E. Orton. Rock waters of Ohio: Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 4, 1898, p. 633. Contains many analyses of deep wells from various horizons. W. H. Norton. Artesian wells of Iowa: Iowa Geol. Survey, vol. 6, 1896, pp. 117-428. 1 On vadose and juvenile carbonic acid in waters, see an elaborate discussion by It. Delkeskamp, Zeitschr. prakt. Geologie, 1906, p. 33; reviewed by W. Lindgren, Econ. Geology, vol. 1, 1906, p. 602. 2 Am. Jour. Sci., 4th ser., vol. 20, 1905, p. 168. 3 Trans. Am. Electrochem. Soc.,vol.8, 1905, p. 291. Schlundt, Jour. Phys.Chem., vol. 18, p.663,1914, has also studied the radioactivity of Colorado springs. * Bull. U. S. Geol. Survey No. 395, 1909. 216 THE DATA OF GEOCHEMISTRY. J. H. Shepherd. Artesian wells of South Dakota: Bull. Agr. Exper. Sta. South Dakota, No. 41, 1895. J. C. Branner. Mineral waters of Arkansas: Ann. Kept. Geol. Survey Arkansas, 1891, vol. 1. E. H. S. Bailey and others. The mineral waters of Kansas: Kansas Univ. Geol. Survey, vol. 7, 1902. P. Schweitzer. A report on the mineral waters of Missouri: Geol. Survey Missouri, vol. 3, 1892. W. S. Blatchley. The mineral waters of Indiana: Twenty-sixth Ann. Kept. Indiana Dept. Geology and Nat. Resources, 1901, pp. 11-225. A. C. Lane. The mineral waters of lower Michigan: Water-Supply Paper U. S. Geol. Survey No. 31, 1899. S. W. McCallie. Preliminary report on the mineral springs of Georgia: Bull. Geol. Survey Georgia No. 20, 1913. W. Anderson. Mineral springs and health resorts of California, San Francisco, 1892. Contains many analyses, the greater number of them by the author. G. A. Waring. Springs of California: U. S. Geol. Survey Water-Supply Paper No. 338, 1914. L. De Launay. Recherche, captage et amenagement des sources thermominerales, Paris, 1899. A. Carnot and others. Analyses of French and colonial mineral waters: Annales des mines, 8th ser., vol. 7, 1885, p. 79; 9th ser., vol. 6, 1894, p. 355; vol. 16, 1899, p. 33. These three papers contain 584 analyses. E. Jacquot and E. Willm. Les eaux minerales de la France, Paris, 1894. Many analyses and descriptions of the springs. Guyon. Etudes sur les eaux thermales de la Tunisie, Paris, 1864. M. Hanriot. Les eaux minerales de l’Algerie, Paris, 1911. A. Raimondi. Aguas minerales del Peru: El Peru, estudios mineralogicos y geologicos, vol. 4, 19Q2, pp. 235-394. L. Darapsky. Aguas minerales de Chile, Valparaiso, 1890. E. H. Ducloux. Aguas minerales alcalinas de la Republica Argentina: Revista Museo de la Plata, vol. 14, pp. 9-52, 1907. Other analyses are in vol. 16, pp. 51-120, 1909. E. Abella y Casariego and J. De Vera y Gomez. Estudio descriptivo de algunas manantiales minerales de Filipinas, Manila, 1893. A. Liversidge, W. Skey, and G. Gray. Rept. Australasian Assoc. Adv. Sci., 1898, pp. 87-108. A collection of analyses of Australasian mineral waters. R. Ishiztj, The mineral springs of Japan. Tokyo, 1915. Deutsches Baderbuch. Leipzig, 1907. A compendium of information relative to the mineral springs of Germany. Many other analyses of waters are scattered through the periodical literature of chemistry, geology, pharmacy, and medicine, and the reports of geological surveys. The publications of agricultural experi- ment stations also contain much material relative to artesian, well, spring, ground, and drainage waters. Daubree’s three volumes on “Les eaux souterraines ” contain few analyses, but much information upon mineral springs. T. Sterry Hunt, in his “Chemical and geolog- ical essays,” also has much to say upon the origin of natural waters and their chemical relations to one another. Bulletins 91 and 139 of. the Bureau of Chemistry, United States Department of Agricul- ture, contain many analyses of American mineral waters. CHAPTER VII. SALINE RESIDUES. DEPOSITION OF SALTS. When a natural water is concentrated by evaporation it deposits its saline constituents in the reverse order of their solubility, the least soluble first, the most soluble last of all. The process, however, is not so simple as it might appear to be, for the solubility of a salt in pure water is one thing and its solubility in the presence of other compounds is another. Each substance is affected by its associates, and its deposition is partly a matter of concentration and partly a question of temperature. In general, the character of a saline deposit can be predicated from the character of the water which yields it; a chloride water gives chlorides, a sulphate water sulphates, and waters of mixed type furnish mixtures of compounds or even double salts. The more complex the water the greater becomes the range of possibilities. We have already seen, in our studies of river, sea, and spring waters what a variety of reactions lead to the deposition of insoluble sediments. By this expression I do not mean sediments of suspended matter, like clays, but precipitates from solution, such as sulphur, hydroxide of iron, sinters, tufas, and so on. These substances repre- sent something more than the results of simple evaporation, for they are produced by chemical changes, like oxidation, loss of carbonic acid, etc. We have now to consider the consequences of evaporation itself, and of the opposite process, re-solution, in which nothing is added to or taken away from the reacting system but water, except in so far as the soluble salts are successively deposited and so removed from the sphere of chemical change. In salt and alkaline lakes we can recognize several stages of this process — the precipitation of the relatively insoluble calcium sulphate, then of salt or sodium sulphate, the production of bitterns, like the water of the Dead Sea, and finally of solid beds of various saline materials. What are these saline resi- dues, and what conditions govern their formation? The most important of these substances, considering the magnitude of the deposits, are sodium chloride and calcium sulphate, and their most probable origin is the evaporation of sea water or its equivalent in either ancient or modern times. The two compounds are commonly associated the one with the other, but not invariably, for gypsum is 217 218 THE DATA OF GEOCHEMISTRY. sometimes derived from other sources, and rock salt may be dissolved and washed away from a given locality, perhaps to he redeposited elsewhere. Still, the concentration of salt water, either from the ocean or from lakes, is the principal source of these deposits, and that phenomenon we may well consider in detail. The process has been going on from Cambrian time down through all the intervening ages to the present day, and it can be observed in actual operation in many accessible localities. A salt lake dries up, or a body of water is cut off from the sea by a bar, and so permitted to evaporate, and a bed of salt is formed. Such beds are lenticular in form — thick at the centers, where the water was deepest, and thinning out toward the edges ; and they show, as a rule, the same alternation of material, hut with variations in regard to completeness. In general, the fol- lowing alternations are observed : First, precipitates are formed, such as were considered in our discussion of mineral springs; then calcium sulphate is deposited, then salt, and finally, under exceptionally favorable conditions, layers of the more soluble compounds which characterize ordinary bitterns. This order, however, is subject to seasonable disturbances. In the concentration of a salt lake the de- posits vary with the temperature, the summer and winter phenomena being often unlike. Again, evaporation goes on during a dry season, to be interrupted by a flood; and in the latter case layers of silt are deposited from time to time over the saline compounds that had previously formed. Alternations of gypsum, salt, and clay are ex- ceedingly common in saline deposits. In a lagoon, cut off from the ocean, a break of the sandy barrier or an exceptionally high tide may admit a fresh supply of material for concentration, and so interrupt the continuity of the process. Any change of conditions will cause a corresponding change in the character of the substances laid down. Evidently each bed of salt should be studied individually, if its history is to be understood; but the general phenomena in the con- centration of sea water appear more or less completely in every case and in essentially the same order. CONCENTRATION OF SEA WATER. In 1849 J. Usiglio 1 published an elaborate study of saline deposits from Mediterranean water, the samples having been taken at sea, near Cette, but several miles from shore and at a depth of 1 meter. The water itself was analyzed, the order and quantity of the salts deposited at various concentrations were determined, and analyses were also made of three bitterns, representing different densities and different stages of the process. The four analyses, reduced to ionic form and to percentages of total solids, appear as follows : 1 Annales chim. phys., 3d ser., vol. 27, 1849, pp. 92, 172. SALINE RESIDUES. 219 Analyses of Mediterranean water and bitterns. A. The water itself, density 1.0258. I C. Bittern of density 1.264. B. Bittern of density 1.21. I D. Bittern of density 1.32. A B c D 01 54. 39 56. 18 49. 99 49. 13 Br 1. 15 1. 22 2. 68 3. 03 S0 4 7. 72 5. 78 14. 64 17. 36 CO, . 18 Na 31. 08 32. 06 20. 39 12. 89 K . 71 . 78 2. 25 3. 31 Oa 1. 18 .26 Ms 3. 59 3.72 10. 05 14. 28 Salinity, per cent 100. 00 3. 766 100. 00 27. 546 100. 00 33. 712 100. 00 39. 619 The determinations of bromine in these analyses are obviously excessive and those of potassium are low, but otherwise the data in the first column, considering the time when they were made, agree fairly well with the more recent figures given in Chapter III of this volume. They show, first, the ehmination of calcium as carbonate, and later as sulphate, then the deposition of sodium chloride, and finally the accumulation of the more soluble substances in the mother liquors. In his study of saline deposition Usiglio started with 5 liters of sea water, and determined the character and quantity of the salts laid down at successive stages of concentration. In the following table the results of his experiments appear, but are reduced to the initial unit volume of 1 liter. The quantities given are in grams. Salts laid down in concentration of sea water. Density.® Volume. Fe 2 03. CaC0 3 . CaS0 4 2H 2 0. NaCl. MgS0 4 . MgCl 2 . NaBr. KC1. 1. 0258 1. 000 1. 0500 .533 0. 0030 0. 0642 1. 0836 .316 Trace. 1. 1037 .245 Trace. 1. 1264 . 190 .0530 0. 5600 1. 1604 .1445 . 5620 1. 1732 .131 . 1840 1. 2015 .112 . 1600 1. 2138 .095 .0508 3. 2614 0. 0040 0. 0078 1. 2212 .064 . 1476 9. 6500 .0130 . 0356 1. 2363 .039 . 0700 7. 8960 .0262 . 0434 0. 0728 1. 2570 .0302 .0144 2. 6240 .0174 .0150 .0358 1. 2778 .023 2. 2720 .0254 .0240 .0518 1. 3069 .0162 1. 4040 .5382 .0274 .0620 Total deposit. . .0030 .1172 1. 7488 27. 1074 .6242 .1532 .2224 Salts in last bittern . . 2. 5885 1. 8545 3. 1640 .3300 0. 5339 Sum .0030 .1172 1. 7488 29. 6959 2. 4787 3. 3172 .5524 .5339 ° Given by Usiglio in Baum^ degrees. Restated here in the usual specific gravities. 220 THE DATA OF GEOCHEMISTEY. Upon further concentration of the mother liquors Usiglio obtained variable results. Mere cooling from the temperature of day to that of night was sufficient to precipitate additional magnesium sulphate which redissolved partially the day following. After that more salt was thrown down, then the double sulphate of magnesium and potas- sium, next the double chloride of the same metals, and finally mag- nesium chloride crystallized out. In the table of results just given the order of deposition is clearly shown. First, ferric oxide and calcium carbonate; then gypsum; then salt, the latter beginning to appear when the water had been concentrated to about one-tenth of its original volume. In its general outlines, then, the concentration of sea water is a simple phenomenon, but in its details it may be very complex. The localities at which it can be completely traced are comparatively few and the natural records of it are, as a rule, defective. The mother liquors are easily drained or washed away, leaving no trace of their existence, and some saline deposits have been partially redissolved and laid down with modified composition elsewhere. Salt and gyp- sum may thus be separated, and so the normal order of their associa- tion becomes disturbed. Beds of salt, therefore, may be divided into classes — as primary and secondary, or as complete and incom- plete, according to their saline character or the evidence of their origin. Of all known localities the region around Stassfurt, in Ger- many, gives us the best record of the complete, or nearly complete, process, and as it has been studied with unusual thoroughness we may properly consider it in some detail. Ocean water, as we have already seen, contains on the average about 3.5 per cent of solid matter in solution, so that the mere evapo- ration of a closed lagoon would give a layer of salt of only moderate thickness. But salt deposits may be enormously thick — a thousand meters or more, as at Sperenberg, near Berlin — and the existence of such masses requires some explanation. For this purpose we must assume that large quantities of brine have accumulated within a limited space, such as a deep valley, like that of the Dead Sea, or behind a bar, as suggested by G. Bischof, 1 and more recently by C. Ochsenius. 2 The theory developed by Ochsenius is briefly as fol- lows : Let us imagine a deep bay, connected with the sea by a narrow and shallow channel, but otherwise cut off from oceanic circulation by a bar. If no large streams enter the bay the outflow from it will be small, but sea water can enter freely to offset the losses due to evaporation. Evaporation, of course, takes place only at the sur- 1 Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 2, 1864, p. 48. 2 Die Bildung der Steinsalzlager und ihrer Mutterlaugensalze, Halle, 1877. See also a short paper in Proc. Acad. Nat. Sci. Philadelphia, 1888, p. 181. Ochsenius was sharply criticized by J. Walther in Das Gesetz der Wiistenbildung, Berlin, 1900. Ochsenius replied in Centralbl. Min., Geol. u. Pal., 1902, pp. 551, 557, 620; and a rejoinder by Walther appeared in the same journal, 1903, p. 211. See also O. E. Branson, Bull Geol. Soc. America, vol. 26. p. 231, 1915. SALINE RESIDUES. 221 face, and the upper layers, thus becoming denser, must sink, so pro- ducing a saline concentration at the bottom. In this manner, being continually supplied with new material from without, the salinity of the bay will gradually increase until saturation is reached and the deposition of salt begins. So long as salt water can enter the bay this process will continue, and the depths of the basin will, in time, become a solid mass of salts, covered with a sheet of bittern. If, meanwhile, an elevation of the land takes place, separating the bay completely from the ocean, evaporation may proceed to its limit and the mother liquor will deposit its contents. In the Karaboghaz and other bays on the eastern shore of the Caspian Sea the process of saline concentration can now be observed in actual operation; but only a part of the program has yet been performed. This theory of Ochsenius, however, is not the only one possible to account for the concentration of salt. It must be remembered that salt is not deposited from sea water until the latter has been concentrated to about one-tenth of its original volume. Suppose, now, a large sheet of water to be cut off from the ocean by any change in the level of the land, and also that it contains within its area a deep depression. In that depression the water will gradually become concentrated, and its saline load will tend to accumulate there. The layer of salt in the depression would be of much greater thickness than one formed by evaporation over a comparatively level bottom, and if the surface area of the depression were small in comparison with that of the original sheet of water, the depth of the deposit might be very great. Such a deposit might also be reenforced by teachings from other salt beds, or from diffused alt in adjacent areas, a process which is now going on in the valley of the Dead Sea. THE STASSFURT SALTS. In the Stassfurt, or, more properly, the Magdeburg-Halberstadt region, the order of deposits is as follows, going from the surface downward : 1 1. Drift, about 8 meters thick. 2. Shales, sandstones, and unconsolidated clays, of varying thickness. 3. Younger rock salt, thickness very variable, sometimes missing. i From data given by H. Precht in Die Salz-Industrie von Stassfurt und Umgegend, 1889; L. Loewe, Zeitschr. prakt. Geologie, 1903, p. 331; H. M. Cadell, Trans. Edinburgh Geol. Soc., vol. 5, 1884, p. 92; and G. Lunge in Thorpe’s Dictionary of applied chemistry, vol. 3, p. 265. See also C. Ochsenius, on Loewe’s paper, Zeitschr. prakt. Geologie, 1904, p. 23; and on the potash salts, idem, 1905, p. 167. J. Westphal (Zeitschr. Berg-, Hiitten- u. Salinenwesen preuss. St., vol. 50, 1902, p. 1) has given a history of the Stassfurt works. An important monograph is that of E. Pfeiffer, Handbuch der Kali-Industrie, Braunschweig, 1887. For a paper by J. Currie, see Trans. Edinburgh Geol. Soc., vol. 8, 1905, p. 403. Other references may be found in a bibliography of saline minerals, Zeitschr. prakt. Geologie, 1905, p. 183. Deutschlands Kali- bergbau, Berlin, 1907, contains papers on the geology of the saline beds by H. Everding, and their chem- istry, by E. Erdmann, with exhaustive bibliographies. See also C. Riemann, Die Geologie der deutschen Salzlagerstatten, Stassfurt, 1908; and H. E. Boeke, Uebersicht der Mineralogie, Petrographic und Geologie der Kalisalzlagerstatten, Berlin, 1909. Many papers relative to the salt deposits are in the journal Kali; but they can not all be noticed here. A recent paper by O. Riedel is in Zeitschr. Kryst. Min., vol. 50, 1912, p. 139. On the quantitative composition of the Stassfurt beds see M. Rozsa, Zeitschr. anorg. Chemie, vol. 90, 1915, p. 377. 222 THE DATA OF GEOCHEMISTRY. 4. Anhydrite, rarely lacking, 30 to 80 meters thick. 5. Salt clay, average thickness 5 to 10 meters, very rarely absent. 6. The carnallite zone, from 15 to 40 meters thick. At Douglashall a layer of rock salt intervenes between the carnallite and the clay. In parts of the field kainite overlies the carnallite, is itself overlain by ‘'sylvinite ” or “hartsalz,” and that in turn by schoenite. These subzones are often missing. 7. The kieserite zone. 8. The polyhalite zone. 9. Older rock salt and anhydrite. Nos. 7, 8, and 9 have a total thickness ranging from 150 to perhaps 1,000 meters. The anhydrite forms layers, averaging 7 millimeters thick, separating the salt into sheets of 8 or 9 centimeters. These layers have been interpreted as annual deposits, due possibly to seasonal variations in temperature or to alternating drought and rain. If this suppo- sition is correct, a Stassfurt salt bed 900 meters thick would require 10,000 years to form. 10. Anhydrite and gypsum. We have now a complete record of the saline deposition at Stass- furt, ranging from the calcium sulphate at the bottom to the mother liquor or carnallite salts at the top. Above the carnallite a protect-, ing layer of clay was laid down; and, after that, probably, a new accession of sea water began the formation of a second series of beds. 1 This younger salt and its underlying anhydrite represent this later period, which has no chemical relation to the first. So much for the broad outlines. Now let us pass on to the details of the record. In the Stassfurt deposits more than 30 saline minerals are found, some abundantly and some sparingly. Several of them are regarded as primary minerals; others are derived from these by secondary reactions; a few of the species are simple salts, but the greater number are double compounds. Chlorides, sulphates, and borates are the characteristic substances, but in kainite we have a mixed salt containing two acid radicles, and the rare sulphoborite is another example of similar complexity. Carbonates are repre- sented but sparingly, and their normal occurrence is probably that of the “ stinkstoiie, ” or bituminous limestone, which has been found beneath the anhydrite. Native sulphur, derived from anhydrite by the reducing action of organic matter, is sparingly present in the salt clay, 2 and more abundantly in the rock salt and carnallite. Pyrites also is sometimes found in the deposits. Bromine is present in the salts and also iodine, 3 and copper is reported by W. Biltz and 1 Some writers regard the younger salt as having been formed by re-solution of older salt and redeposition here. As the discussion is geological and not chemical, it is unessential to our present purposes. 2 Pfeiffer, Arch. Pharm., 3d ser., vol. 27, 1890, p. 1134. On the salt clay see E. Marcus and W. Biltz, Zeitschr anorg. Chemie, vol. 68, 1910, p. 91. Vanadium was detected in it. See also Marcus, idem, vol. 77, p. 119, 1912, for many analyses. 3 On bromine see H. E. Boeke, Zeitschr. Kryst. Min., vol. 45, 1908, p. 346. On iodine, A. Frank, Zeitsclir. angew. Chemie, vol. 20, 1907, p. 1279; E. Erdmann, idem, vol. 23, 1910, p. 342; and K. Kraze, Inaug. Diss. Halle, 1909. The presence of iodine in the salts of the Stassfurt region proper is questioned by Boeke, Erdmann, and Kraze. Kraze, however, found it in the salts from Xcu Stassfurt, Bleicherode, and Kalusz. See also K. Koehlichen, Kali, vol. 7, 1913, p. 457. On rubidium in potash salts see E. Wilke, Kali, vol. 6, 1912, p. 245. SALINE RESIDUES. 223 E. Marcus, as well as ammonium and nitrates. 1 Helium occurs in the salts in traces. 2 The essential compounds are chlorides and sulphates, and as the latter are represented by the oldest of the important strata they may be considered first. The sulphates found at Stassfurt are as follows: Anhydrite -CaS0 4 . Gypsum 3 CaS0 4 .2H 2 0. Glauberite CaS0 4 .Na 2 S0 4 . Polyhalite 2CaS0 4 .MgS0 4 .K 2 S0 4 .2H 2 0. Krugite 4CaS0 4 .MgS0 4 . K 2 S0 4 .2H 2 0 . Kieserite - MgS0 4 .H 2 0. Epsomite MgS0 4 .7H 2 0 (reichardtite) . Vanthoffite MgS0 4 .3Na 2 S0 4 . Bloedite MgS0 4 .Na 2 S0 4 .4H 2 0 (astrakanite). Loewite MgS0 4 .Na 2 S0 4 .2-|H 2 0 . Langheinite 2MgS0 4 . K 2 S0 4 . Leonite MgS0 4 . K 2 S0 4 .4H 2 0 . Picromerite MgS0 4 . K 2 S0 4 . 6H 2 0 (schoenite) . Aphthitalite K 3 Na(S0 4 ) 2 (glaserite) . 4 Kainite MgS0 4 . KC1 . 3H 2 0 . Celestite, SrS0 4 , is also sometimes found in these deposits. If we now study these compounds with reference to their origin, we shall find that the primary deposition followed approximately in the order of their hydration. Anhydrous calcium sulphate, anhy- drite, forms the lowest member of the series, and gradually merges into the older salt. In the latter, glauberite and langbeinite, both anhydrous, first appear, although they also occur, always as second- ary minerals, higher up. According to H. Precht, 5 6 langbeinite replaces polyhalite when the calcium sulphate needed to form the latter mineral is present in insufficient quantity. Polyhalite, in which the ratio of the sulphate molecules to water is as four to two, comes next, forming an important part of the upper layers in the older salt, and is followed by the monohydrated kieserite. Krugite, which is still lower in hydration, occurs with polyhalite in the younger salt, so that the two species may be regarded as equivalent and contemporaneous. The more highly hydrated species, bloedite, loewite, picromerite, and leonite, are principally found in the kainite region above the carnallite, and epsomite, with its seven molecules of water, is deposited in the salt clay. The anhydrous aphthitalite 1 Zeitschr. anorg. Chemie, vol. 62, 1909, p. 183; vol. 64, 1909, p. 236. 2 It. J, Strutt, Proc. Roy. Soc., vol. 81, ser. A, 1908, p. 278. E. Erdmann, Ber. Deutsch. chem. Gesell., vol. 43, 1910, p. 777. S. Valentlner, Kali, vol. 6, 1912, p. 1. 3 Probably, as A. Geuther (Liebig’s Annalen, vol. 218, 1883, p. 297) has shown, the formula here given to gypsum should be doubled. It then becomes Ca2S 2 08.4H 2 0, and the hemihydrate, Ca 2 S 2 0 8 .H 2 0, a well-known artificial compound, furnishes evidence in favor of the higher formula. 4 According to B. Gossner (Zeitschr. Kryst. Min., vol. 39, 1904, p. 155) glaserite is a definite species with the formula given above. J. H. Van’t Hoff and H. Barschall (Zeitschr. physikaL Chemie, vol. 56, 1906, p. 212) question the definiteness of the mineral, and regard it as a mixture of the two component sulphates. 6 Zeitschr. angew. Chemie, 1897, p. 68. 224 .THE DATA OF GEOCHEMISTRY. is a secondary mineral in the kainite, and vanthofiite, also anhydrous, is associated with aphthitalite and loewite in the same horizon. The loewite is probably formed by dehydration of bloedite, 1 and the yanthofhte by a reaction between bloedite and sodium sulphate, the process being modified by the presence of other substances. The langbeinite of the kainite region. is commonly regarded as a secondary product, but it may have been one of the parent species, for F. K. Mallet, 2 who has described this mineral as found in the Punjab salt range of India, observed that on exposure to moist air it gained 57 per cent in weight and altered into a mixture of epsomite and picro- merite. On the other hand, langbeinite itself may be derived by various reactions from other Stassfurt species, such as leonite, kainite, kieserite, and picromerite, as Van’t Hoff and Meyerhoffer have shown. The fact that a given salt may be produced by several different reactions warns us to be cautious in making assertions as to its origin at any specified point. Concentration and temperature are two of the determining factors in the deposition of salts, and the possible reactions are also profoundly modified by the presence of other compounds. Van’t Hoff and his colleagues have determined experimentally many of the conditions under which the Stassfurt minerals occur or can be produced, and find that their temperatures of formation in a saturated solution of common salt are lower than in the absence of that compound. The elaborate researches of these authors, however, are not available for abstraction here, partly because they are complicated by diagrams, and partly because the investigations are still being continued. Only in a special mono- graph upon the Stassfurt beds could all the details of their investi- gations be adequately discussed. 3 The chlorides found in the Stassfurt region are as follows : Halite or rock salt, NaCl. Sylvite, KC1. “Sylvinite” is a mixture of sylvite and rock salt, while the “Hart- salz ” contains these substances together with kieserite. Douglasite, K 2 FeCl 4 .2H 2 0.(?) Carnallite, KMgCl 3 .6H 2 0. Tachhydrite, 2MgCl 2 .CaCl 2 .12H 2 0=3(RCl 2 .4H 2 0) . 4 Bischofite, MgCl 2 .6H 2 0. 1 See J. H. Van’t Hoff, Sitzungsb. Akad. Berlin, 1902, p. 414. Also Van’t Hoff and W. Meyerhoffer, idem, 1903, p. 678; 1904, p. 659. 2 Mineralog. Mag., vol. 12, 1899, p. 159. s Van’t Hoff and his associates have already published about fifty papers on the Stassfurt salts, in Sitzungsb. Akad. Berlin, from 1897 to 1907. See also Van’t Hoff, Physical chemistry in the service of the sciences, Chicago, 1903; Zur Bildung der ozeanischen Salzablagerungen, Braunschweig, 1905; and an address in Ber. Internat. Kong, angew. Chemie, Berlin, 1903. Also summaries by E. F. Armstrong, Proc. British Assoc. Adv. Sci. 1901, p. 262, and E. Janecke, Zeitschr. anorg. Chemie, 1906, p. 7. For a graphic representation of the saline associations see also H. E. Boeke, Zeitschr. Kryst. Min., vol. 47, 1910, p. 273. * Boeke, in a private communication, suggests that if the formula of carnallite is doubled, to K 2 Mg2Cl6.12H 2 0, tachhydrite becomes CaMg 2 Cl<5.12H 2 0. That is, the salts are analogous, Ca in one replacing K 2 in the other. SALINE RESIDUES. 225 With the exception of the rock salt, which forms the great mass of the deposits overlying the anhydrite, these chlorides represent the concentration of the mother liquors in the carnallite zone. They were the most soluble compounds potentially existing in sea water, and, with the sulphato-chloride, kainite, were among the last substances to crystallize. Halite and douglasite were distinctly primary deposits; carnallite was generally, and sylvite occasionally, primary; tachhydrite and bischofite were secondary products. Kainite was sometimes one and sometimes the other. The “Hartsalz,” according to Van’t Hoff and Meyerhoffer, 1 is a secondary product formed by the action of solutions upon a mixture of carnallite, kieserite, and sodium chloride, which was preceded by the splitting up of kainite into sylvite and kieserite. The kainite, in its most conspicuous develop- ment, lies between the carnallite and the “Hartsalz.” From the car- nallite itself, sylvite and bischofite may be derived, or it may be formed by the direct union of these species, which are its two com- ponents. According to C. Przibylla, 2 when sylvite and bischofite combine to form carnallite, there is an increase of 4.95 per cent in volume. Possibly, therefore, the formation of carnallite at low levels is prevented by pressure. In one essential respect, the foregoing paragraph demands qualifi- cation. According to Boeke 3 the existence of douglasite is doubtful. Another mineral, rinneite, discovered by him in the “Hartsalz” of Saxony and the Harz, has the formula FeCl 2 .3KCl.NaCl. 4 The sub- stance named douglasite may have been identical with this. Boeke, moreover, regards the “Hartsalz” as a direct deposition for the reason that it is distinctly stratified. Two other chlorides, not found at Stassfurt, have been described from similar deposits in adjacent regions. Koenenite, discovered by F. Rhine 5 in salts from Volpriehausen in the Sollingerwald, has the complex formula Al 3 0 3 .3Mg0.2MgCl 2 .6 or 8H 2 0. Baeumlerite, from the Leine valley in Hannover, according to O. Renner 6 is KCl.CaCl 2 . With the carnallite and its overlying potassium salts, the borates generally occur. They are boracite, sulphoborite, pinnoite, aschar- ite, and heintzite; one other, hydroboracite, is found earlier in the series, near the lower limit of the polyhalite zone. These species are 1 Sitzungsb. Akad. Berlin, 1902, p. 1106. See also J. H. Van’t Hoff, F. B. Kenrick, and H. M. Dawson, Zeitschr. physikal. Chemie, vol. 39, 1902, p. 27, on the conditions of formation of tachhydrite. 2 Centralbl. Min., Geol. u. Pal., 1904, p. 254. 3 Neues Jahrb., 1909, Bd. 2, p. 19. For the first description of rinneite, see Centralbl. Min., Geol. u. Pal., 1909, p. 72. On the synthesis of rinneite see Boeke, Sitzungsb. Akad. Berlin, vol. 24, 1910, p. 632. Boeke has described the iron compounds of the Stassfurt beds in Neues Jahrb., 1911, Bd. 1, p. 48, and Centralbl. Min., Geol. u. Pal., 1911, p. 48. See also F. Rinne and R. Kolb, idem, p. 357. * O. Schneider (Centralbl. Min., Geol. u. Pal., 1909, p. 503) regards the NaCl of rinneite as a mechanical admixture. 5 Centralbl. Min., Geol. u. Pal., 1902, p. 493. 6 Idem, 1912, p. 106. 97270°— Bull. 616—16 15 226 THE DATA OF GEOCHEMISTRY. relatively rare, except the boracite, and it is not necessary to consider them any further at this point, for their occurrence tells us little about the main phenomena of saline concentration. We must not suppose, for an instant, that these zones of deposition are regularly and completely separated, nor even that they represent in any close degree the products observed in the artificial evaporation of sea water or brine. In the latter case a moderate quantity of water is concentrated by itself; at Stassfurt more water was continually added from the ocean. On the one hand calcium sulphate is deposited almost wholly at one time; on the other new quantities were precipi- tated so long as the evaporating bay retained its connection with the sea. In the salt pan gypsum forms a bottom layer before salt begins to separate out; at Stassfurt anhydrite is found in greater or less amount through all the zones, and so also is the sodium chloride. When a shallow lake or isolated lagoon evaporates, the artificial process is closely paralleled, but a concentration with continuous replenishment lasting for thousands of years is a very different thing. The principles are unchanged, the broad outlines remain the same, but the details of the process are greatly modified. E. Erdmann 1 regards the Stassfurt salts as having been formed from a shallow portion of the Permian ocean, which covered a great part of North Germany and became isolated from the main sea. The evaporation products collected in depressions of the land and were reinforced by calcium sulphate from fresh-water affluents. Sea water alone contains too little calcium to account for the anhy- drite present in the beds. Walther’s views are similar. Both reject the “bar” theory. We are now in a position to trace more distinctly the phenomena which attended the formation of the beds at Stassfurt . 2 For a long time only gypsum was deposited; but later, as the concentration of the bay increased, salt also was laid down, and by its action the gyp- sum was converted into anhydrite . 3 From this point onward, for a considerable period, the calcium sulphate derived from the influx of sea water above fell through a deep layer of concentrated brine and was deposited directly as anhydrite, in alternating layers with the salt . 4 When, however, so much salt had been precipitated that the supernatant solutions had become bitterns rich in magnesium salts, the calcium sulphate united with these salts, and polyhalite was formed. The polyhalite region at Stassfurt is essentially a bed of 1 Zeitschr. angew. Chemie, vol. 21, 1908, p. 1685. A short additional communication by Erdmann is in the same journal, vol. 22, 1909, p. 238. 2 Cf. G. Lunge, Thorpe’s dictionary of applied chemistry, vol. 3, 1893, p. 268. 3 According to J. H. Van’t Hoff and F. Weigert, Sitzungsb. K. Akad. Wiss. Berlin, 1901, p. 1140, anhy- drite forms from gypsum in sodium chloride solutions at 30°. In sea water the transformation takes place at 25°. 4 Cf. J. H. Van’t Hoff and P. Farup, Sitzungsb. Akad. Berlin, 1903, p. 1000. H. Vater (idem, 1900, p. 270) discusses marine anhydrite, and gives many references to literature. At ordinary temperatures, according to Vater, calcium sulphate crystallizes from a saturated solution of salt in the form of gypsum. SALINE RESIDUES. 227 rock salt, containing, with other impurities, from 6 to 7 per cent of the new mineral. Possibly syngenite, CaK 2 (S0 4 ) 2 .H 2 0, a species which occurs in a similar deposit at Kalusz in Galicia, but which does not seem to be recorded from Stassfurt, was first produced. Syn- genite may be prepared artificially by the direct action of potassium sulphate upon gypsum, and it is converted by strong solutions of mag- nesium chloride and sulphate into polyhalite. 1 The occurrence of syngenite at Kalusz is below the potassium salts, in rock salt contain- ing anhydrite. It is therefore the equivalent in position of polyhalite. 2 As the concentration of the magnesian mother liquors increased, kieserite was produced, the dehydrating action of magnesium chlo- ride preventing the formation of epsomite. H. Precht and B. Witt- jen 3 have shown that when magnesium chloride and sulphate are dissolved together and the solution then evaporated upon the water bath, kieserite separates out. Thus the kieserite zone was formed, which contains, on an average, 65 per cent of rock salt, 17 of kieserite, 13 of carnallite, 3 of bischofite, and 2 of anhydrite. At this point polyhalite disappears. The last step in the concentration was the formation of carnallite, with its associated minerals, from the chlo- rides which had hitherto remained in solution. The average com- position of this zone is 55 per cent of carnallite, 25 of rock salt, 16 of kieserite, and 4 of various other minerals. The kainite layers above the carnallite were probably formed by the action of perco- lating waters upon the latter mineral, in presence of some kieserite. Finally, a protecting layer of mud or clay was laid down over the mass of salts, preventing in great measure, but perhaps not entirely, their subsequent re-solution. Into all of the foregoing reactions one element entered which counts for little in their imitation on a small scale — namely, the element of time. The prolonged action of the mother liquors, during thousands of years, upon the earlier deposits, must have been much more thorough than their effect during an experiment in the laboratory. In the latter case the solid deposits are usually removed from time to time, so that the procedure does not accurately repeat the operations of nature. These considerations should especially be taken into account in studying the transforma- tion of gypsum into anhydrite, or the reverse reaction which has often been observed. 4 Beds of anhydrite may take up water and be 1 E. E. Basch, Sitzungsb. K. Akad. Wiss. Berlin, 1900, p. 1084. 2 A. Aigner (Oesterr. Zeitschr. Berg- u. Hiittenw., 1901, p. 686) has described the Austrian polyhalite. For analyses of kainite, carnallite, etc., from Kalusz and Aussee, see C. von John, Jahrb. K.-k. geol. Reichsanstalt, vol. 42, 1892, p. 341. On mirabilite from Kalusz, see R. Zalozieeki, Monatsh. Chemie, vol. 13, 1892, p. 504. Two papers on the potash salts of Austria and the Tyrol by R. Gorgey are in Min. pet. Mitt., vol. 28, 1909, p. 334, and vol. 29, 1910, p. 148. Gorgey (idem, vol. 31, 1912, p. 339) has also described the potash salts of Wittelsheim, Alsace. 3 Ber. Deutsch. chem. Gesell., vol. 14, 1881, p. 2131. * Cf. F. Hammerschmidt, Min. pet. Mitt., vol. 5, 1882-83, p. 272; and J. F. McCaleb, Am. Chem. Jour., vol. 11, 1889, p. 34. 228 THE DATA OF GEOCHEMISTRY. reconverted into gypsum through considerable depths, as at Bex in Switzerland, where the alteration has reached a thickness of 60 to 100 feet. Time is an important factor in all such transformations, especially when one of the reacting bodies happens to be a solid of relatively low solubility. The temperature conditions which governed the deposition of the Stassfurt salts are briefly summed up by Van’t Hoff 1 as follows: 1. Glauberite, formed above 10°. 2. Langbeinite, formed above 37°. 3. Loewite, formed above 43°. 4. Vanthoffite, formed above 46°. 5. Loewite with glaserite, formed above 57°. 6. Loewite with vanthoffite, formed above 60°. 7. Kieserite with sylvite, formed above 72°. This scale of temperatures is designated as a “ geological ther- mometer,” and gives us something like a definite idea of past condi- tions in the Stassfurt beds. 2 OTHER SAI/T BEDS. The Stassfurt deposits, as has already been indicated, are alto- gether exceptional in their completeness. Rock salt is generally found in much thinner deposits, and as a rule it is unaccompanied by potassium or magnesium salts in any notable quantities. Gypsum or anhydrite, however, is commonly present, either under the salt or in its near neighborhood. Where gypsum is absent we may infer, with a fair degree of probability, that the salt is of secondary origin and not derived directly from sea water, or that it came from the evaporation of a salt lake which contained either no calcium or no sulphates. Gypsum, of course, cannot form unless its constituents are at hand. Furthermore, gypsum may be produced otherwise than from the concentration of sea water, and it may exist as a remainder where the more soluble salts have been washed away. It can occur independently of or concomitant with the presence of rock salt, and each locality must be considered on its individual merits. On some small coral islands in the Pacific gypsum is found as a resi- due from the evaporation of lagoons, in beds which may reach 2 feet in thickness. 3 Here the origin from sea water is evident. On the other hand, waters containing little or no salt often deposit gypsum. I. C. Russell, 4 for instance, has described such a deposit at Fillmore, 1 Zeitschr. Elektrochemie, vol. 11, 1905, p. 709. 2 The scientific investigation of the Stassfurt salts is being continued by a society formed for that pur- pose. For a list of the publications of its members see Van’t Hoff, Sitzungsb. K. Akad. Wiss. Berlin, No. 39, 1910, p. 772. 3 J. D. Dana, Manual of geology, 4th ed., p. 120. On the Cis-Indus (India) salt beds, which contain potassium salts, see W. A. K. Christie, Rec. Geol. Survey India, vol. 44, 1914, p. 241. * Mon. U. S. Geol. Survey, vol. 11, 1885, p. 84. The deposition of gypsum by Lake Chichen-Kanab, Yucatan, was mentioned in Chapter V. SALINE EESIDUES. 229 Utah, which covers an area of 12 square miles and has been opened to a depth of 6 feet without reaching bottom. Gypsum is also com- mon as an efflorescence or incrustation in caves, 1 and it can be pro- duced by the alteration of other rocks. The oxidation of pyrites in limestone may form gypsum ; or, as was shown in the preceding chap- ter, it can originate from double decomposition between other metallic sulphates and calcium carbonate. L. W. Jowa, 2 for example, pre- pared selenite in measurable crystals by the action of a solution of ferrous sulphate on chalk. In the Salina formation of New York gypsum occurs above the salt, and its presence is attributed by Dana 3 to the alteration of the overlying “ Waterlime” beds. In this region the salt occurs in layers interstratified with shales, a series of shallow-water deposits having been successively covered by bodies of mud or clay. 4 At Goderich, Canada, a similar but not identical alternation has been observed. 5 Here a boring 1,517 feet deep revealed dolomite and anhydrite, and above that were six beds of salt alternating with similar materials. The uppermost salt was struck at 1,028 feet, and at 876 feet dolomite, with seams of gypsum, was found. The anhydrite at bottom was probably normal; but what the upper gypsum signifies is not clearly shown. It may be the beginning of an unfinished concentration, or else quite independent of the salt below. Throughout the region of salt more or less anhydrite was found, but potassium compounds were either absent or present only in traces. Neither in New York nor in the Goderich deposits were the mother liquors permitted to crystallize. 6 The great salt deposits of Louisiana and Texas are associated not only with gypsum but also with sulphur, sulphurous gases, and petroleum. At first, before the petroleum was discovered, the salt beds were regarded as of marine origin. 7 Later, R,. T. Hill 8 inter- preted them as derived from hot saline waters rising from great depths, and a similar view was put forth by L. Hager. 9 E. Coste, 10 a strenuous advocate of the volcanic origin of petroleum, has argued that the salt is its obvious companion, but his argument is hardly conclusive. Sodium chloride is known as a volcanic sublimate, and * See G. P. Merrill, Proc. U. S. Nat. Mas., vol. 17, 1905, p. 77. s Annales Soc. g6ol. Belgique, vol. 23, 1895-96, p. cxxviii. 3 Manual of geology, 4th ed., p. 554. 1 See sections given in Bull. New York State Mus. No. 11, 1893. 5 T. S. Hunt, Geol. Survey Canada, Rept. Progress, 1876-77, p. 221. 6 The solubility of calcium sulphate, gypsum, anhydrite, etc., in water and various solutions has been elaborately studied. See an excellent summary by F. K. Cameron and J. M. Bell, in Bull. No. 33, Bur. Soils, U. S. Dept. Agr., 1906. 7 See, for example, G. I. Adams, Bull. U. S. Geol. Survey No. 184, 1901, p. 49. Also doubts raised by C. W. Hayes and W. Kennedy in Bull. U. S. Geol. Survey No. 212, 1903, p. 144. 8 Jour. Franklin Inst., vol. 154, 1902, p. 273. 9 Eng. and Min. Jour., vol. 78, 1904, pp. 137, 180. 10 Jour. Canadian Min. Inst., vol. 6, 1903, p. 73. 230 THE DATA OF GEOCHEMISTRY. some authors have argued that the salt of the ocean is volcanic also ; but extreme views of this sort are rarely sound. The most that can be said is that the origin of the Louisiana-Texas salt has not yet received its final interpretation . 1 It would be most unwise to claim that all salt deposits are formed in the same way. Some are certainly marine, some are residues from salt lakes, others may represent con- centrations from magmatic waters. The subject, however, is so large that a more extended discussion of it is impracticable here. ANALYSES OF SALT. Neither salt nor gypsum is found in nature in a state of absolute purity, although that condition is sometimes very nearly approxi- mated. Being deposited from solutions containing other substances, some of the latter are always carried down and reveal their presence on analysis. Analyses of rock salt are exceedingly numerous, and only a moderate number, enough to show the range of variation in the mineral, need be cited here . 2 1 In Bull. Geol. Survey Louisiana No. 7, 1908, G. D. Harris describes the salt deposits and discusses their origin. He also gives a very complete summary of information on the salt deposits of the world. The fullest treatise on salt, covering the globe, is by J. O. von Buschman, Das Salz, 2 vols., Leipzig, 1906 and 1909. 2 See Thorpe’s Dictionary of applied chemistry, vol. 4, p. 430, for additional data. Also Geol. Survey Michigan, vol. 3, appendix B, and vol. 5, pt. 2, for Michigan salt and brines; Bull. New York State Hus. No. 11, for New York examples; Prel. Rept. Geol. Louisiana, 1899, for material from that State; and C. I. Istrati, Bull. Soc. chim., 3d ser., vol. 2, 1889, p. 4, for analyses of Roumanian salt. Some Roumanian samples contain as high as 99.9 per cent of sodium chloride. SALINE RESIDUES. 231 Analyses of rock salt. A. Salt from Goderich, Canada. Analysis by Gould, for T. Sterry Hunt, Geol. Survey Canada, Rept. Progress, 1876-77, p. 233. B. Salt from Kingman, Kansas. Analysis by E. H. S. Bailey and E. C. Case, Kansas Univ. Geol. Survey, vol. 7, 1902, p. 73. Ten other analyses of rock salt are given, mostly purer than this. C. Saline incrustation, Tuthill Marsh, Kansas. Idem, p. 70. Analysis made in the University of Kansas laboratory, but analyst not named. D. Salt from Petit Anse, Louisiana. Analysis by F. W. Taylor, Mineral Resources U. S. for 1883, U. S. Geol. Survey, p. 564. E. Salt from Leoncito, La Rioja Province, Argentina. Analysis by L. Harperath, Bol. Acad. nac. cien. Cdrdoba, Argentina, vol. 10, 1890, p. 427. Remarkable for its high proportion of potassium salts. Har- perath gives nineteen analyses of Argentine salt, some of them representing great purity, but several approaching this one. F. Salt stalactite from a disused working at Redhaugh colliery, Gateshead, England. Analysis by W. H. Dunn, published by P. P. Bedson, Jour. Soc. Chem. Ind., vol. 8, 1889, p. 98. This analysis, in the original, is stated in the form of radicles. It is recalculated here to salts for uniformity with the others. G. Salt from bed deposited by the Katwee Lake, north of the Albert Edward Nyanza, central Africa. Analysis by H. S. Wellcome; abstract in Jour. Soc. Chem. Ind., vol. 9, 1890, p. 734. An analysis of the lake water by A. Pappe and H. D. Richmond is also given in this journal. See ante, p. 173. A B C D E F G NaCl 99. 687 97. 51 71. 82 98. 731 81. 491 99. 00 82. 71 KC1 17. 483 CaCl 2 .032 Trace. .52 MrCL .095 . 10 .013 .15 ^ x 2 Na 2 S0 4 . .57 21. 98 5. 32 k 2 so 4 .048 8.43 CaS0 4 .090 1. 51 .99 1. 192 .978 MgS0 4 1. 29 Na 2 C0 3 3. 56 2. 46 ALOo } - 13 Fe 2 0 3 .11 .010 .15 Si0 2 J .024 Insoluble .017 .20 .23 H 2 0 .079 .030 .28 .82 100. 000 100. 00 100. 00 100. 000 100. 000 99. 95 99. 89 In addition to the impurities shown in the analyses, rock salt fre- quently contains gaseous inclusions. These have been often exam- ined, recently by N. Costachescu , 1 who finds some of them to consist mainly of nitrogen, and others mainly of methane. Other hydro- carbons and carbon dioxide are also found. Rock salt is not uncom- monly colored, especially blue. This coloration has been attributed to organic matter, and recently, by H. Siedentopf , 2 to the presence of minute particles of metallic sodium. This very remarkable con- clusion would seem to require confirmation. 1 Ann. Univ. Jassy, vol. 4, 1906, p. 3. The author gives a good summary of earlier investigations. 2 Physikal. Zeitschr., vol. 6, 1905, p. 855. See also L. Wohler and H. Kasamowski, Zeitschr. anorg. Chemie, vol. 47, 1905, p. 853, and F. Cornu, Centralbl. Min., Geol. u. Pal., 1907, p. 166, and Neues Jahrb., 1908, p. 32. G. Spezia (Centralbl. Min., Geol. u. Pal., 1909, p. 398) cites experimental evidence adverse to Siedentopf’s views. E. Erdmann (Ber. Deutsch. chem. Gesell., vol. 43, p. 777) ascribes the blue of salt to radioactivity, which is known to effect color changes in minerals. 232 THE DATA OF GEOCHEMISTEY, ANALYSES OF GYPSUM. For gypsum the following analyses, all made in the laboratory of the United States Geological Survey, are sufficient to show its usual character : 1 Analyses of gypsum. A. From Hillsboro, New Brunswick. Analysis by George Steiger. B. From Alabaster, Michigan. Analysis by Steiger. C. From east of Cascade, Black Hills, South Dakota. Analysis by Steiger. D. E. From Nephi, Utah. Analyses by E. T. Allen. This material evidently contains admixed anhy- drite. A B c D E so 3 46. 18 46. 18 45. 45 48. 14 39. 53 co 2 .85 . 65 7. 73 Cl Trace. .03 Trace. .04 Si0 2 . 10 AloOq 1 \ .12 Fe 2 0 3 } . 10 / .08 } . 14 CaO 32. 37 32. 33 32. 44 35. 29 38. 46 MgO Trace. 1 .05 .33 Trace. . 24 Na-0 } 14 .07 K 2 0 / . 10 . 19 H 2 0 20. 94 20. 96 20. 80 15. 88 12. 69 Insoluble .10 .05 .45 99. 79 99. 82 100. 09 99. 96 99.54 BITTERNS. In what has been said so far, we have considered almost exclusively the concentration of sea water; but other waters form other deposits and yield different bitterns. Analyses of bittern are not often reported, and only a few examples can be given here . 2 These analyses are recalculated to ionic form, and give the percentage composition of the anhydrous saline matter. 1 For other data relative to the composition and origin of gypsum, see G. P. Grimsley and E. H. S. Bailey, Univ. Geol. Survey Kansas, vol. 5, 1899. Also E. C. Eckel, Bull. U. S. Geol. Survey No. 213, 1903, p. 407; G. P. Grimsley, Geol. Survey Michigan, vol. 9, pt. 2, 1903-4, and Am. Geologist, vol. 34, 1904, p. 378; F. A. Wilder, Jour. Geology, vol. 11, 1903, p. 723; A. L. Parsons, Twenty-third Rept. State Geologist, New York State Mus., 1903; and G. I. Adams and others, on gypsum deposits of the United States, Bull. U. S. Geol. Survey No. 223, 1904. A recent report on the gypsum of New York is by D. H. Newland and H. Leighton, Bull. New York State Mus. No. 143, 1910. On the genetic relations of gypsum and anhydrite, see R. C. Wallace, Geol. Mag., 1914, p. 276. 2 In addition to Usiglio’s analyses cited on p. 219, ante. SALINE RESIDUES. 233 Analyses of bitterns. A. Bittern from Leslie Salt Refining Works, San Mateo, California. Analysis by R. F. Gardner. From sea water. B. Bittern of maximum concentration, from the brines of Syracuse, New York. Analysis by C. A. Goessmann, Am. Jour. Sci., 2d ser., vol. 44, 1867, p. 80. C. Bittern from Pomeroy, Ohio. Analysis by A. R. Merz and R. F. Gardner. D. Bittern from Hartford, West Virginia. Merz and Gardner, analysts. E . Bittern from Saginaw, Michigan. Gardner analyst. Analyses A, C, D , E recalculated to percentages from the figures given by J. W. Turrentine in U. S. Dept. Agric., Bur. Soils Bull. No. 94, 1913. Selected from a number of analyses reported on pp. 61-66. F. Bittern from the saline of Medellin, Antioquia, Colombia. Analysis by J. B. Boussingault, Annales chim. phys., 5th ser., vol. 2, 1874, p. 102. Known locally as “oil of salt.” G. Bittern from salt works of Allendorf-an-Werra, Germany. Analysis by Reichardt, abstract in Jour. Chem. Soc., vol. 42, 1882, p. 24. « A B C D E F G Cl 56. 33 63. 93 62. 42 62. 70 60. 18 44. 99 55. 56 Br .94 1. 16 2. 07 2. 21 1. 33 1. 02 .22 I Trace. . 03 S0 4 9. 38 .06 . 93 .69 Trace. 14. 07 15. 08 Na 22. 83 10. 24 .46 .04 25. 27 25. 97 10. 62 K 2. 58 5. 27 .57 .53 .49 11. 18 6. 40 Li Trace. .01 nh 4 .09 Ca . 38 11. 26 26. 00 25. 97 9. 82 . 28 . 07 Mg 7. 56 8. 08 7. 55 7. 86 2. 91 2. 37 8. 81 SiO .02 Organic 3. 21 Salinity, per cent 100. 00 31. 82 100. 00 33. 567 100. 00 55. 88 100. 00 55. 23 100. 00 32. 97 100. 00 33. 478 100. 00 29. 149 Although these bitterns vary widely in composition, in consequence of the differences between the original brines, they are nearly all note- worthy as showing the concentration in them of bromine. The Mich- igan brines are important commercial sources of bromine, and so, too, are those of the Kanawha Valley, in West Virginia. A. L. Baker 1 reports that 20 to 30 gallons of Kanawha bittern wdll yield 1 pound of bromine, and he has also shown that they contain iodine in very appreciable amounts, from 38.4 to 59.2 milligrams per liter. The richness of the Dead Sea in bromine has already been pointed out. Bitterns of this class deserve a more careful study than they seem to have yet received. SODIUM SULPHATE. In the evaporation of ocean water the sulphates which form are first the calcium compound and then the magnesium salt, or else double sulphates of magnesium, with either calcium or sodium. Anhydrite, then polyhalite, and then kieserite, follow one another in regular succession. In many saline lakes, however, calcium and mag- nesium are deficient in quantity, while sodium sulphate is present in relatively large amounts. In such lakes sodium sulphate is deposited in considerable quantities, generally preceding the deposition of salt, i Chem. News, vol. 44, p. 207, 1881. 234 THE DATA OF GEOCHEMISTRY. and its precipitation is determined or affected by the season of the year. Sodium sulphate is much more soluble in warm than in cold water, but the similar variation for salt is comparatively small; so that the mere change of temperature between summer and winter may cause mirabilite to separate out, or to redissolve again. An instance of this kind, in the Karaboghaz, has already been noticed, and the Great Salt Lake 1 not only deposits sodium sulphate during winter, but even casts it up in heaps upon the shore. The salt thus formed is the decahydrate, mirabilite, Na 2 SO 4 .10H 2 O; while from warm solutions, especially from concentrated brines, the anhydrous sulphate thenardite may be deposited. In warm and dry air mira- bilite effloresces, loses its water, and is transformed into thenardite, which is a well-known and common mineral. On the surface of Lacu Sarat, in Roumania, 2 large crystals of mirabilite form during winter, to redissolve, at least in part, when the weather becomes warm, and many other sulphate or sulphato-chloride lakes exhibit similar phenomena. The Siberian lakes, studied by F. Ludwig. 3 deposit mainly sulphates; sodium sulphate in Lakes Altai, Beisk, Domoshakovo, and Kisil-Kul, while in the Schunett Lake a quantity of magnesium sulphate is also formed. Ludwig gives analyses of these precipitates, but the three in the subjoined table are enough to cite here. The analyses are carried by Ludwig to four decimal places, but I have rounded them off to two. He also gives the Na and Cl of the sodium chloride separately, and the insoluble residue he divides into organic and inorganic. The consolidation of the data as tabulated below is for the sake of simplicity. Their subdivision does not help to illustrate the phenomena now under discussion. Analyses of saline deposits in two Siberian lakes. A. Deposit on bottom of Lake Altai. B. Deposit on shore of Lake Altai. C. Deposit on shore of Schunett Lake. A B C co 2 0. 12 0. 03 0. 63 so, 54. 00 55. 67 54. 45 Na 2 0 41.64 43. 21 25. 96 K 2 0 1. 93 NaCl . 29 . 13 .92 CaO .22 .01 .07 MgO .11 10. 22 A1 2 0 3 } .01 .07 Fe,0, .11 .01 Si0 2 .07 Insoluble residue 3. 46 .91 5. 70 99. 95 99. 97 100. 03 1 G. K. Gilbert, Mon. U. S. Geol. Survey, vol. 1, 1890, p. 253. 2 L. Mrazec and W. Teisseyre, Apergu goologique sur les formations saliferes et les gisements de sel en Itoumanie, 1902. This memoir contains a bibliography relative to Roumanian salt. 3 Zeitschr. prakt. Geologie, vol. 11, 1903, p. 401. Cf. ante, p. 170. SALINE RESIDUES. 235 These lakes, Altai and Schunett, are sulphato-chloride waters, but the first effect of their concentration is to bring about a partial separa- tion of their salts. The same effect is perhaps even better exem- plified by Sevier Lake, in Utah, which is at times entirely dry, form- ing a thin saline layer that in moister seasons partly redissolves . 1 The deposits from this lake have been analyzed, those from the margin by O. D. Alien, those from the center by S. A. Lattimore, and their average composition, as cited by Gilbert, is given below: Average composition of deposits from Sevier Lake , Utah. Margin. Center. Na 2 S0 4 14.3 84.6 NaoCO, .4 NaCl 75.8 7.0 CaS0 4 Trace. MgS0 4 5.5 Trace. k 2 so 4 . 7 h 2 o 3. 6 8.0 Insoluble . 1 Trace. 100.0 100.0 Here the sodium sulphate tends to accumulate at the center of the lake, whereas the later deposits, which are covered by a crust of sodium chloride, are formed in larger relative proportion around the margin. Fractional crystallization, however, is only a part of the process by which the saline constituents of a water may be separated. Salt and alkaline lakes are peculiarly characteristic of desert regions, and the smaller depressions may be alternately dry and filled with water. Suppose, now, following a suggestion of J. Walther , 2 that such a lake, concentrated to a bed of salt covered by a thin sheet of bittern, is overwhelmed by desert sands, so that a permanent saline deposit, protected from further change, is formed. The bittern will be absorbed by the sandy covering, its salts will rise by capillary attraction to the surface, and the efflorescence thus produced will be scattered in dust by the winds. On the steppes of the lower Volga, according to Walther, there are numerous remainders of salt lakes, which have been thus covered, and where, beneath the sand, solid salt of great purity is found. The mother liquors have vanished, and their saline constituents have been scattered far and wide. 1 G. K. Gilbert, Mon. U. S. Geol. Survey, vol. 1, 1890, pp. 224-227. See p.156, ante, for the composition of the brine. 2 Das Gesetz der Wiistenbildung, Berlin, 1900, p. 149. Chapter 13 is devoted to the subject of desertsalts. See also T. H. Holland (Proc. Liverpool Geol. Soc., vol. 11, p. 227, 1912) on the origin of desert salts. 236 THE DATA OF GEOCHEMISTRY. MISCELLANEOUS DESERT SALTS. Wherever deserts exist, there these saline residues are common. They are peculiarly abundant in the western part of the United States, especially in the Bonneville and Lahontan basins and over the so-called alkali plains, and they exhibit a great variety of com- position. Chlorides, sulphates, carbonates, and borates occur, sepa- rately or together, and many analyses of these products have been recorded. To the sulphato-chloride class the subjoined analyses be- long, the other saline deposits being left for separate consideration later. 1 Analyses of saline deposits from sulphato-chloride waters. A. Salt, Osobb Valley, Nevada. Analysis by R. W. Woodward, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 707. B. Saline efflorescence on desert, south of Hot Springs station, Nevada. Analysis by O. D. Allen, idem, p. 773. C. Incrustation from Quinns River crossing, Black Rock Desert, Nevada. Analysis by O. D. Allen, idem, p. 791. D. Salt from Salt Lake, 7 miles east of the Zandia Mountains, New Mexico. Analysis by O. Loew, Rept. U. S. Geol. Surveys W. 100th Mer., vol. 3, 1875, p. 627. E. Efflorescence from alkali flat, near Buffalo Spring, Nevada. Analysis by O. D. Allen, op. cit., p. 731. F. Efflorescence from Santa Catalina, Arizona. Analysis by O. Loew, op. cit., p. 628. G. Salt from shore of lake near Percy, Nevada. Analysis by R. W. Woodward, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 148. H. Efflorescence on loess, near Cordoba, Argentina. Analysis by Doering, cited by A. W. Stelzner, Beitrage zur Geologie und Palaeontologie der Argentinischen Republik, 1885. A number of salts, etc., are described on pages 295-309. This one is remarkably rich in potassium. A B c D E F G H NaOl 96. 49 95. 67 85. 27 82. 57 70.81 5. 93 0. 74 10.81 Na 2 S0 4 1. 91 1. 75 6. 89 26. 38 94. 04 46. 27 53. 14 Na^Oa .96 2. 59 k 2 so 4 1. 94 32. 34 MgCl 2 . 5. 88 MgS0 4 48. 28 CaS0 4 1. 63 Trace. 4. 45 3. 71 H 2 0 . 52 . 73 8. 57 4. 66 Insoluble residue. . .12 1. 97 1. 82 100. 00 100. 00 100. 00 100. 00 99. 13 99. 97 99. 74 100. 00 These analyses, taken in connection with those of salt given on page 231, show the same order of variation as is found in the parent waters themselves. Chlorides form one end of the series, sulphates the other; and every gradation may exist between the two. Even dif- ferent parts of the same deposit may show evidence of such a grada- tion, as in Sevier Lake, where separation of the salts has gone on to a greater or less extent; but partial re-solution in time of high water can reverse the process and bring about a new distribution of the soluble substances. 1 A number of analyses of similar products from Argentina are given by F. Schickendantz, Revista del Museo de la Plata, vol. 7, 1895, p. 1. See also G. J. Young, Bull. U. S. Dept. Agric. No. 61, 1914, on the salines of the Great Basin, and several papers by II. S. Gale in Bull. U. S. Geol. Survey No. 540-N, 1913. SALINE RESIDUES. 237 ALKALINE CARBONATES. From alkaline lakes alkaline carbonates are deposited, mingled with chlorides and sulphates in varying proportions. In Hungary, Egypt, Armenia, and Venezuela such deposits are found, and they are pecu- liarly common in the Lahontan basin of Nevada, and in southern California. In Nevada they often form “playas,” or “playa lakes ’ n — beds which are dry in summer and flooded to the depth of a few inches during the wet season. A number of these alkaline incrustations were analyzed by the chemists of the Fortieth Parallel Survey, with the results shown in analyses A to F of the subjoined table . 1 2 With these may be included two analyses of the soluble parts of incrusta- tions, made by T. M. Chatard in the laboratory of the United States Geological Survey. Analyses of incrustations deposited by alkaline lakes. A. From western arm of Black Rock Desert, near the so-called “Hardin City,” Nevada. Analysis by O. D. Allen, vol. 2, 1877, p. 792. B. From Ruby Valley, Nevada. Analysis by R. W. Woodward, vol. 1, 1878, p. 503. C. From valley of Deep Creek, Utah. Analysis by Woodward, vol. 2, p. 474. D. From Antelope Valley, Nevada. Analysis by Woodward, vol. 2, p. 541. E. From a point near Peko station, on Humboldt River, Nevada. Analysis by W oodward, vol. 2, p. 594. F. From Brown’s station, Humboldt Lake, Nevada. Analysis by Woodward, vol. 2, p. 744. G. From surface of playa, north arm of Old Walker Lake, Nevada. Soluble portion, 29.78 per cent. H. Five miles west of Black Rock, Nevada. Soluble portion, 23.10 per cent. A B C D E F G H Na,CO a 52. 10 58. 69 25. 12 25. 95 48. 99 7. 02 72. 69 9. 06 NaHC0 3 8. 09 14. 76 14. 35 36. 01 11. 13 NajSCh 27. 55 28. 32 17. 43 33. 31 4. 42 49. 67 17. 49 27. 05 NaCl 18. 47 2. 11 38. 01 24. 51 7.24 20. 88 2. 53 59. 32 Na 2 B 4 0 7 3. 34 11. 30 4. 15 1.00 k 2 so 4 2. 79 4. 68 1. 88 KC1 1. 18 1. 39 Si0 2 1. 96 2. 18 98. 12 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 The following table contains analyses, reported by E. W. Hilgard , 3 of the soluble part of “alkali” incrustations from California. They exhibit remarkable peculiarities of composition, especially in their contents of potassium salts, nitrates, and phosphates. 1 See I. C. Russell, Mon. U. S. Geol. Survey, vol. 11, 1885, p. 81. 2 The analyses are here cited as recalculated by T. M. Chatard, Bull. U. S. Geol. Survey No. 60, 1890, pp. 55, 56. The original statements do not adequately discriminate between carbonates and bicarbonates. a Appendix, Rept. Univ. California Exper. Sta., 1890. Other analyses are given in this report. 238 THE DATA OF GEOCHEMISTRY. Analyses of “alkali” incrustations from California . A. From Visalia, Tulare County. B. From Westminster, Orange County. C. From the experiment station, Tulare County. D. From the Merced bottoms, Merced County. A B c D Na 2 C0 3 65. 72 62. 22 32. 58 25. 28 14. 75 19. 78 2.25 75. 95 4. 67 1.46 12. 98 4. 94 Na 2 S0 4 NaCl 3. 98 10. 57 NaN0 3 NaH 2 P0 4 8. 42 k 2 co 3 6. 59 20. 62 k 2 so 4 20. 23 1. 65 3. 95 MgS0 4 (NEL),COq 1.41 X 11 JJ -4/2 vyv - , 3 100. 00 100. 00 100. 00 100.00 Similar deposits are formed by the two soda lakes at Ragtown, Nevada, and these have been worked for commercial purposes. Two samples were collected by Arnold Hague in 1868, before working began; a third, representing the marketable product, was examined by T. M. Chatard. 1 The analyses are as follows, in the form adopted by Chatard : Analyses of deposits from Soda Lakes , Ragtown, Nevada. A. Big Soda Lake. Analysis by O. D. Allen, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 748. B. Little Soda Lake. Analysis by Allen, op. cit., p. 759. C. Little Soda Lake, market soda. Analysis by Chatard. A B C Na 2 C0 3 45. 05 44. 25 52. 20 NaHC0 3 34. 66 34. 90 25. 05 Na 2 S0 4 1.29 . 99 5. 10 NaCl 1. 61 1.10 3. 31 Si0 2 .27 Insoluble . 80 2. 81 H 2 0 16. 19 15. 95 14. 16 99. 60 100. 00 100. 09 These soda lakes also deposit crystals of gaylussite, of the formula CaC0 3 .Na 2 C0 3 .5H 2 0, 2 although the analysis of the water 3 reveals no calcium. Probably the minute quantities of calcium that enter the waters from springs or otherwise are immediately removed in this form. It will be observed, on examining the foregoing analyses, that they represent variable mixtures of several salts. The latter, of course, 1 Bull. U. S. Geol. Survey No. 60, 1890, p. 52. Chatard cites a number of analyses of foreign urao or trona. For analyses of Egyptian urao see O. Popp, Liebig’s Annalen, vol. 155, 1870, p. 348. 2 See analysis by O. D. Allen, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 749. 3 See p. 159, ante, for analysis of the water. SALINE RESIDUES. 239 have been calculated from the analytical data, and the radicles might have been combined somewhat differently, but without any essential change in the general results. Several of the analyses are reckoned upon the basis of anhydrous material, and are so far incorrect, but they show with a fair degree of accuracy the relative proportions of the several compounds which were present. The carbonates were probably three in number — thermonatrite, Na 2 C0 3 .H 2 0; natron, Na 2 CO 3 .10H 2 O; and trona, or urao, Na 2 C0 3 .NaHC0 3 .2H 2 0. Some- times one and sometimes another of these salts is in excess, but the third is the most important, as the elaborate researches of Chatard a have shown. That this is the first salt to be deposited from waters of this class his experiments upon Owens Lake water clearly prove. At Owens Lake, Inyo County, California, the manufacture of sodium carbonate has been carried out upon a commercial scale. In order to determine the most favorable conditions for the process, Chatard subjected a quantity of the water to fractional crystalliza- tion and analyzed the salts which were successively deposited. Two concordant series of experiments were made, together with a less complete but corroborative set, on water from Mono Lake. The results of the first group were as follows: Analyses of salts deposited by fractional crystallization from water of Owens Lake , California. A. The natural water of Owens Lake. Specific gravity 1.062 at 25°. Salinity 77.098 grams per liter. This analysis, which represents the composition of the anhydrous residue, was cited on page 160 with all carbonates as normal; it is here restated in conventional form. B. First crop of crystals. Water concentrated to one-fifth its original volume. Specific gravity of mother liquor 1.312 at 27.9°. C. Second crop of crystals. Specific gravity of mother liquor 1.312 at 25°. D. Third crop of crystals. Specific gravity of mother liquor 1.315 at 26.25°. E. Fourth crop of crystals. Specific gravity of mother liquor 1.327 at 35.75°. F. Fifth crop of crystals. Specific gravity of mother liquor 1.300 at 13.9°. This crop was obtained by chilling the solution, in order to determine the effect of cold. A B c D E F h 2 o 14. 51 4. 33 3. 43 2. 24 11. 03 Na 2 C0 3 34. 95 43. 75 22. 84 18. 19 12. 51 55. 04 NaHC0 3 7. 40 30. 12 10. 53 4. 06 3.88 4. 09 Na 2 S0 4 14. 38 3. 18 25. 44 26. 70 19. 01 5. 70 NaCl 38. 16 7. 44 35. 06 45. 59 60. 99 19. 16 Na 2 B 4 0 7 .63 NaB0 2 & 2. 01 KC1 4. 07 1.07 1. 12 1. 14 1. 21 2. 93 (CaMg)CCL .08 . 14 (AlFeUX .05 .01 1 .09 i .06 .01 .02 Si0 2 .28 .055 .05 .16 Organic matter .032 J Insoluble .078 100. 00 100. 385 99. 41 99. 17 99. 90 100. 14 a Chatard supposes that the biborate could not exist in so strongly alkaline a solution as the mother liquor from which this crop was obtained. b Natural soda; its occurrence and utilization: Bull. U. S. Geol. Survey No. 60, 1890, pp. 27-101. Cf. E. Le Neve Foster, Proc. Colorado Sci. Soc., vol. 3, 1890, p. 245, for data concerning Owens Lake. See also G. Lunge, Zeitschr. angew. Chemie, 1893, p. 3. On natural soda in Egypt see A. Lucas, Survey Dept. Paper (Egypt) No. 22, 1912. 240 THE DATA OF GEOCHEMISTRY. From these analyses we see that the first crop of crystals consists largely of trona, Na 2 C0 3 .NaHC0 3 .2H 2 0, with a small excess of the normal carbonate, some chloride, and some sulphate. In C, D, and E the carbonates diminish, but the normal salt is even more largely in excess, while the chlorides increase rapidly. The final, chilled solu- tion deposits chiefly sodium carbonate, with some chloride and less sulphate. The order of deposition is trona, sodium sulphate, sodium chloride, and finally, if we ignore the minor constituents of the water, the very soluble normal carbonate. Of the trona itself Chatard made several analyses, and he also prepared a series of artificial products, which established the true formula of the compound. 1 The best specimen of trona from Owens Lake had the composition given in the first column below, which is compared with the composition as calculated theoretically. Composition of trona from Owens Lake, California. Found. Calculated. Na 2 C0 3 45. 86 46. 90 NaHCO, 36.46 37. 17 NaCl .32 Na 2 S0 4 1. 25 h 2 o 16. 16 15. 93 Insoluble .02 100. 07 100. 00 The prevalent view concerning the origin of the Lahontan alkalies was stated in Chapter V (p. 159). The waters of the Bonneville basin, or of Great Salt Lake, originate in an area of sedimentary rocks and contain chiefly substances which were formed during earlier concen- trations. In one sense, then, we may call the residues of that region secondary depositions. The Lahontan area, on the other hand, is rich in volcanic materials, from which, by percolating waters charged with atmospheric or volcanic carbon dioxide, the soluble substances were withdrawn. These substances have accumulated in the waters of the basin, except for the calcium carbonate, which is now seen in the enormous masses of tufa so characteristic of the region. To Mono and Owens lakes, lying just outside of the Lahontan basin, the same observations apply. Alkaline carbonates, together with sulphates and chlorides, have been formed by solution from eruptive rocks, and concentrated in these waters and their residues. The seepage waters from fresh springs near Owens Lake percolate through beds of volcanic ash, and contain even a higher proportion of alkaline carbonates than Cf. also C. Winkler, Zeitschr. angew. Chemie, 1893, p. 446; and B. Reinitzer, idem, p. 573. SALINE RESIDUES. 241 the lake itself. 1 The rocks from which the salts were originally derived seem to have been mainly rhyolites, andesites, and other varieties rich in alkalies and relatively poor in lime. Had lime been present in larger quantities more calcareous sediments and gypsum would have formed, with less of the alkaline carbonates, or even none at all. This theory, however, which attributes the presence of alkaline car- bonates to a direct derivation from volcanic rocks, is not the only hypothesis possible. Even if it holds with respect to the Lahontan waters it is not necessarily valid elsewhere. In order to account for the existence of sodium carbonate in natural waters, T. Sterry Hunt 2 assumed a double decomposition between sodium sulphate and cal- cium bicarbonate, gypsum being thrown down. A similar reaction is accepted by E. von Kvassay 3 in his study of the Hungarian soda, only in this case sodium chloride is taken as the initial compound. The latter salt is supposed to react upon calcium bicarbonate, yield- ing sodium bicarbonate, which effloresces, while the more soluble cal- cium chloride, simultaneously formed, diffuses into the ground. E. W. Hilgard 4 has shown experimentally that both reactions are possible, and that either sodium sulphate or sodium chloride can react with calcium bicarbonate, forming strongly alkaline solutions. From such solutions crystals of gypsum can be deposited, while sodium bicarbonate remains dissolved. In Hilgard’s experiments, however, he precipitated and removed the calcium sulphate by means of alco- hol, a condition unlike anything occuring in nature. S. Tanatar, 5 therefore, repeated the experiments without the use of alcohol and confirmed Hilgard’s conclusions. The reverse reaction is hindered by the crystallization of the gypsum and the washing away or efflorescence of the soluble carbonate. E. Sickenberger, 6 who examined the natron lakes of Egypt, ob- served the presence in them of alg96, and noticed the evolution of hydrogen sulphide from their waters, iron sulphide being at the same time thrown down. He therefore ascribes the carbonates to the reduction of sulphates by organic matter, and subsequent absorption 1 See analyses by T. M. Chatard, Bull. U. S. Geol. Survey No. 60, 1890, p. 94. Chatard also discusses the origin of the carbonates and cites the views of earlier investigators concerning other localities. 2 Am. Jour. Sci., 2d ser., vol. 28, 1859, p. 170. 3 Jahrb. K.-k. geol. Reichsanstalt, 1876, p. 427. Cf. also H. Le Chatelier on Algerian salts, Compt. Rend., vol. 84, 1877, p. 396. Von Kvassay gives a bibliography of the Hungarian occurrences and some analyses of the soda. * Am. Jour. Sci.,4thser., vol. 2, 1896, p. 123. See also paper in Rept. Univ. California Agr. Exper. Sta., 1890, p. 87, followed by an experimental research by M. E. Jaffa. 5 Ber. Deutsch. chem. Gesell., vol. 29, 1896, p. 1034. See also a memoir by H. Vater, Zeitschr. Kryst. Min., vol. 30, 1899, p. 373. 6 Chem. Zeitung, 1892, pp. 1645, 1691. 97270°— Bull. 616—16 16 242 THE DATA OF GEOCHEMISTRY. of carbon dioxide from the air. G. Schweinfurth and L. Lewin , 1 on the contrary, while admitting that such a process can go on to some extent, regard it as capable of accounting for only a small part of the alkaline carbonates that are formed. These lakes deposit sodium chloride, sulphide, and carbonate; and the authors attribute the last salt to double decompositions with carbonate of lime. The percolat- ing Nile waters contain calcium bicarbonate and the soil through which it reaches the lakes is rich in salt and gypsum. These two sub- stances first react to form sodium sulphate and calcium chloride and the former then exchanges with calcium bicarbonate, as in Hunt’s and Hilgard’s investigations. Sodium chloride is taken as the starting point, and from it the sulphate and carbonate are derived. We have, then, three theories by which to account for the forma- tion of alkaline carbonates in natural waters and soils . 2 First, by direct derivation from volcanic rocks. Second, by reduction of alkaline sulphates. Third, by double decomposition between cal- cium bicarbonate and alkaline sulphates or chlorides. All three are possible, and all three are doubtless represented by actual occurrences in nature. The presence of sodium carbonates in the waters of hot springs, which, it may be observed, are common in the Lahontan basin, we can ascribe to the operation of the first process ; the second mode of derivation is effective wherever alkaline sulphates and organic matter are found together; the third method is perhaps the most general of all. To the action between alkaline salts and cal- cium bicarbonate, Hilgard attributes the common presence of sodium carbonate in the soils of arid regions, a mode of occurrence which is very widespread and of the utmost importance to agriculture. The reclamation of arid lands by irrigation is profoundly affected by the presence of these salts, which sometimes accumulate to such an extent as to destroy fertility. Excessive irrigation may defeat its own purpose and destroy the value of land which might be reclaimed from the desert by a more moderate procedure . 3 The soluble salts which exist below the surface, being dissolved, rise by capillary attraction and form the objectionable crusts of “ alkali.” 1 Zeitschr. Gesell. Erdkunde, vol. 33, 1898, p. 1. Several references to bacteriologic researches are given in this memoir. 2 To these theories may be added a fourth, that of C. Ochsenius (Zeitschr. prakt. Geologie, 1893, p. 198), who supposes that the alkaline carbonates have been formed by the action of carbon dioxide, commonly of volcanic origin, on the “mother-liquor salts.” The evidence in favor of this view is so slender that a discussion of it would be hardly worth while. s The reports of the Bureau of Soils, U. S. Dept. Agr., and of the agricultural experiment stations of sev- eral Western States contain abundant literature on this subject. The report of the Division of Soils for 1900 contains a paper by F. K. Cameron on the application of the theory of solution to the study of soils, in which the generation of alkaline carbonates by double decomposition is discussed on the basis of modem physical chemistry. In Bull. 42 of the New Mexico College of Agriculture there is a summary of the lit- erature on alkali soils. A remarkable deposit of natron in San Luis Valley, Colorado, is described by W. P. Headden, Am. Jour. Sci., 4th ser., vol. 27, 1909, p. 305. SALINE RESIDUES. 243 BORATES. Borates and nitrates are much less frequently deposited and in much smaller amounts than the salts which we have so far been con- sidering. They are, however, important saline residues and deserve a more extended study than they seem to have yet received. In the chapter upon closed basins attention was called to the Borax Lake of northern California, and among mineral springs a number containing borates were noted. The latter were hot springs, situated in volcanic regions, as in the Yellowstone Park — a mode of occur- rence which must be borne in mind if we are to determine the origin of these substances. We must also remember that borates exist in sea water, from which source the deposits at Stassfurt are supposed to be derived. Two sets of facts, therefore, have to be considered in dealing with this class of compounds. Let us first examine the actual occurrences of borates as saline residues . 1 Borax Lake, Lake County, California, has been repeatedly de- scribed . 2 Its water contains chiefly sodium carbonate and sodium chloride, with borax next in importance, and it deposits the last- named salt in crystals, some of which are several inches long. More borax, however, was furnished by a neighboring smaller lake, Ha- chinchama. The supply probably came, according to Becker, from hot springs near the lakes, and one spring, of which the analysis has already been given, contains not only boron, but also a surpris- ing quantity of ammonium compounds. The same association of borates with ammoniacal salts is also to be observed in the waters of the Yellowstone Park, and especially in that unique solution known as “ the Devil’s Inkpot.” The hot springs of the Chaguarama Valley, in Venezuela , 3 furnish a similar example; and here again, as in some of the California localities described by Becker, sulphur and cinnabar are deposited. Boric acid and ammonium chloride are among the volcanic products of the island of Vulcano ; 4 but the famous “sofhoni” or “fumaroles” of Tuscany are of much greater importance. Here jets of steam carrying boric acid emerge from the ground and supply great quantities of that substance for industrial purposes. The following compounds of boron are deposited, by the lagoons in which the boric-acid vapors are concentrated: Sassolite H 3 B0 3 (orthoboric acid). Larderellite (NH 4 ) 2 B 8 0 13 .4H 2 0. Bechilite CaB 4 0 7 .4H 2 0 (borocalcite). Lagonite Fe /// 2 B 6 0 12 .3H 2 0. 1 For general information about American localities see Mineral Resources U. S. for 1882, U. S. Geol. Survey, p. 566; 1883-84, p. 858; 1889-90, p. 494; and 1901, p. 869. 2 Geol. Survey California, Geology, vol. 1, 1865, p. 97. G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, pp. 264-268. H. G. Hanks, Third Ann. Rept. State Mineralogist (California). For analyses of the water and of an adjacent hot spring, see ante, pp. 160, 197. This lake, situated about 80 miles north of San Francisco, must not be confused with Searles’s “ Borax Lake” in San Bernardino County. 3 See E. Cortese, Eng. and Min. Jour., vol. 78, November 10, 1904. 4 See A. Bergeat, Zeitschr. prakt. Geologie, 1899, p. 45. 244 THE DATA OF GEOCHEMISTRY. One of these salts is an ammonium borate, and another ammonium compound — boussingaultite, (NH 4 ) 2 Mg(S0 4 ) 2 .6H 2 0 — is also formed at this locality. According to C. Schmidt 1 the condensible vapors from the fumaroles of Monte Cerboli contain boric acid and am- monia in considerable amounts, with much less hydrogen sulphide. Water issues with the vapors, and in samples condensed from several vents C. M. Kurtz 2 found solid contents ranging from less than 1 to more than 7 grams per liter. Four of the lagoon waters examined by Kurtz contained the following quantities of foreign matter: Foreign matter in Tuscan lagoon waters. [Grams per liter.] Total solids. . Boric acid (H 3 BO 3 ). Ammonium sulphate. Castelnuovo 8. 565 4. 154 1. 695 Larderello 6. 720 4. 032 . 760 Monte Rotondo, uppermost lagoon 2. 005 1. 100 .253 Monte Rotondo, lowest lagoon 22. 575 19. 300 .587 The high figures of the last example represent a concentration from all the upper waters, which are united at the lowest level. In the dark-brown sediment of the lagoons Schmidt found gypsum, am- monium sulphate, ammonium thiosulphate, ammonium sulphide, ammonium Carbonate, magnesia, and a little soda and potash mixed with a clay derived from dolomite and colored by iron sulphide. He also analyzed the mother liquor left by the lagoon waters after most of their boric acid had been deposited. I have reduced his analysis to percentages of total solids, and essentially to ionic form, except that for the excess of boric acid I prefer to use the symbol H 3 B0 3 . Schmidt gives the total solids as 16.374 grams per liter, reckoning the free acid as B 2 0 3 ; as recalculated the sum becomes 18.548. The revised figures are as follows: Analyses of mother liquor from Tuscan lagoon water. • Grams, per liter. Grams, per liter Cl . . 0. 39 Ca 0. 16 so 4 .. 49.37 Mg 1.99 B0 3 in borates . . 2. 50 (Al, Fe) 2 0 3 . . . 06 H 3 BO 3 .. 26.92 Mn 2 0 3 Na .. .89 Si0 2 Trace. K NH 4 . . 1 . 01 .. 16.71 100 . 00 1 Ann. Chem. Pharm., vol. 98, 1856, p. 273. In vol. 102, 1857, p. 190, Schmidt also describes the rocks of the region. 2 Dingler’s Polyt. Jour., vol. 212, 1874, p. 493. SALINE RESIDUES. 245 In the light of all the foregoing data, we may reasonably assume that there is a relation between boric acid and ammonium, at least wherever hot springs carry appreciable quantities of borates. The boron and the nitrogen appear together, a fact which has led to the hypothesis that boron nitride, decomposed by steam, has been the parent compound. 1 Boron nitride, BN, is a well-known artificial substance; it is very stable and, with steam, gives the required reaction, but it has not yet been observed as a natural mineral species. Its invocation, then, as an agent in the production of borates is purely hypothetical, however probable it may be. The same objection applies to Dumas’s suppo- sition that boron sulphide, B 2 S 3 , also decomposed by steam, was the source of the boric acid contained in the “ soffioni.” 2 That hypothesis was indicated by the presence of hydrogen sulphide in the boron- bearing vapors. P. Bolley 3 suggested that a reaction of ammonium chloride on borax, which he proved to be experimentally possible, might give rise to the observed phenomena; and E. Bechi, 4 in a later memoir than the one previously cited, traced the borates to the neigh- boring ophiolitic serpentines, in which he found at least one inclu- sion of datolite, a borosilicate of lime. The serpentine, heated to 300° in a current of steam and carbonic acid, yielded boric acid, ammonium compounds, and hydrogen sulphide — the very products found in the fumaroles. Serpentine, however, is a secondary rock, and may have derived its borates and ammonium salts from the solutions which brought about the transformation of the original gabbro. In recent years E. Perrone 5 and R. Nasini 6 have suggested that the Tuscan boric acid may be derived from the decomposition, by water, of tourmaline contained in deep-seated granites. Nasini supports this opinion by showing that steam at high temperatures extracts boric acid from tourmaline. The suggestion, however, does not account for the ammonium compounds associated with the boric acid. 1 R. Warington, Chem. Gaz., 1854, p. 419, with special reference to Vulcano, Lipari Islands. H. Sainte- Claire Deville and F. Wohler, Ann. Chem. Pharin., vol. 105, 1858, p. 71. O. Popp, idem, 8th supp. Bd., 1870, p. 5. E. Bechi, Bull. Soc. ind. min., vol. 3, 1857-58, p. 329. A. Lacroix (Compt.. Rend., vol. 147, 1908, p. 161) has found ammonium chloride and boric acid in recent fumaroles of Vesuvius. 2 See paper by A. Payen on the Tuscan fumaroles, Annales chim. phys., 3d ser., vol. 1, 1841, p. 247. He adopts Dumas’s theory. 3 Aim. Chem. Pharm., vol. 68, 1848, p. 125. 4 Atti R. accad. Lincei,3d ser., vol. 2, 1878, p. 514. See also a summary by H. Schiff in Ber. Deutsch. chem. Gesell., vol. 11, 1878, p. 1690. 6 Carte idrographica d’ltalia, No. 31, 1904, p. 355. 6 Abstract in Geol. Centralbl., vol. 8, 1906, p.413; and Atti R. accad. Lincei, 5th ser., vol. 17, 1908, p. 43. For criticisms of Perrone and Nasini, see G. d’Achiardi, Atti Soc. toscana sci. nat., Memorie, vol. 23, 1907, p. 8, and Rend. R. accad. Lincei, 5th ser., vol. 17, 1908, p. 238. For a long paper on the origin of boric acid and the borates, see A. d’Achiardi, Atti Soc. toscana sci. nat. Pisa, 1878, vol. 3, fasc. 2. Earlier memoirs are by H. Coquand, Bull. Soc. g<§ol. France, 2d ser., vol. 6, 1848-49, p. 91; C. Sainte-Claire Deville and F. Leblanc, Compt. Rend., vol. 45, 1857, p. 750; vol. 47, 1858, p. 317; and F. Fouqud and H. Gorceix, idem, vol. 69, 1869, p. 946. The gases from the “soffioni” have been studied by R. Nasini, F. Anderlini, and R. Salvadori (AttiR. accad. Lincei, 5th ser., Memorie, vol. 2, 1895, p. 388), as well as by some of the above- named authorities. Carbon dioxide is the principal gas. 246 THE DATA OF GEOCHEMISTRY. An entirely different mode of occurrence for borates is shown on an extensive scale in Nevada and southern California and at a few localities in Oregon. 1 Here borax, as such, is found in considerable quantities; but the calcium salts ulexite and colemanite are by far the more important species. In Esmeralda County, Nevada, at Teel’s marsh, Rhodes’s marsh, Columbus marsh, and Fish Lake, ulexite, NaCaB 5 0 9 .8H 2 0, is the principal borate. It occurs in nodules, known locally as “cotton balls,” which have a fibrous structure and seem to be in process of formation, the smaller masses gradually becoming larger. 2 At Rhodes’s marsh, according to Joseph Le Conte, 3 the central part of the area is occupied by a bed of common salt, around which there are deposits of sodium sulphate. Beyond the sulphate beds the borax and ulexite are found. These “marshes,” which are really playa lakes, are of secondary origin; and M. R. Campbell, speaking of the similar formations in California, 4 attributes their borates to leachings from beds of Tertiary sediments. The borates of southern California are widely scattered over a large area, which is practically a continuation of the Nevada field. They are found especially in Inyo and San Bernardino counties, in Death Valley, along the basin of the Amargosa River, and elsewhere. The locality known as Searles’s marsh, or Searles’s borax lake, has been worked since 1873; and as it has yielded a number of new mineral species, it deserves special consideration here. In chemical interest it rivals Stassfurt, although its systematic study is hardly more than begun. Borings at this point, according to De Groot, 5 6 have revealed the following succession of deposits: Section at Searles’s marsh , San Bernardino County , California. Feet. 1. Salt and thenardite 2 2. Clay and volcanic sand, with some hanksite 4 3. Volcanic sand and black clay, with bunches of trona 8 4. Volcanic sand, containing glauberite, thenardite, and a few crystals of hanksite 8 5. Solid trona, overlain by a thin layer of very hard material 28 6. Mud, smelling of hydrogen sulphide and containing layers of glauberite, soda, and hanksite 20 7. Clay, mixed with volcanic sand and permeated with hydrogen sulphide 230+ 1 See H. G. Hanks, Third Ann. Kept. State Mineralogist California, 1883, and Am. Jour. Sci., 3d ser., vol. 37, 1889, p. 63; H. De Groot, Tenth Ann. Rept. California State Mining Bureau, 1890; G. E. Bailey, The saline deposits of California: Bull. No. 24, California State Mining Bureau, 1902. For the geology of the borax deposits in Death Valley and the Mohave Desert, see M. R. Campbell, Bull. U. S. Geol. Survey No. 200, 1902, and an article in Eng. and Min. Jour., vol. 74, 1902, p. 517. An important memoir on the borax deposits of the United States, by C. R. Keyes, is in the Bull. Am. Inst. Min. Eng., 1909, p. 867. 2 Rept. State Mineralogist Nevada, 1871-72, p. 35. 3 Third Ann. Rept. State Mineralogist California, 1883, p. 51. 4 Bull. U. S. Geol. Survey No. 213, 1903, p. 401. See also J. E. Spurr, Bull. U. S. Geol. Survey No. 208, 1903. 6 Tenth Ami. Rept. California State Mining Bureau, 1890, p. 535. SALINE RESIDUES. 247 The borax of Searles’s marsh is found chiefly in the top crust, or crystallized in the water which sometimes accumulates in the depres- sions of the bed. This layer is reproduced by slow degrees, through capillary action, which brings up the soluble salts from below, so that the same area can be repeatedly worked over. In the workings the following mineral species have been found: 1 Anhydrite CaS0 4 . Gypsum CaS0 4 . 2H 2 0 . Celestite SrS0 4 . Thenardite Na 2 S0 4 . Mirabilite Na 2 SO 4 .10H 2 O. Glauberite Na 2 Ca(S0 4 ) 2 . Sulphohalite 2 Na 6 (S0 4 ) 2 ClF. Hanksite Na 22 K(S0 4 )9(C0 3 ) 2 Cl. Borax Na 2 B 4 0 7 . 10H 2 O . Colemanite Ca 2 B 6 0! x .5H 2 0 . Calcite CaC0 3 . Dolomite MgCa(C0 3 ) 2 . Natron NaCO 3 .10H 2 O. Trona Na 3 H(C0 3 ) 2 .2H 2 0 . Gaylussite 3 Na 2 Ca(C0 3 ) 2 .5H 2 0. Pirssonite 3 Na 2 Ca(C0 3 ) 2 .2H 2 0. Northupite 3 Na 3 Mg(C0 3 ) 2 Cl. Tychite 4 Na 6 Mg 2 (C0 3 ) 4 S0 4 . Halite NaCl. Soda niter NaN0 3 . Searlesite 5 Na 2 0.B 2 0 3 .4Si0 2 .2H 2 0. Sulphur, from reduction of sulphates . 6 In the water from 15 feet below the crust, or “ crystal layer,” ammonium salts are reported to occur — a fact which becomes pecul- iarly significant when it is considered in connection with the presence of soda niter also. To this point we shall recur later. It is evident that the paragenesis of all these mineral species presents a complex chemical problem, quite analogous to that investigated by Van’t Hoff in his studies of the Stassfurt beds. 1 De Groot also mentions cerargyrite, embolite, and gold; but these minerals have no obvious relationship to the other species. 2 S. L. Penfield, Am. Jour. Sci., 4th ser., vol. 9, 1900, p. 425. s J. H. Pratt, Am. Jour. Sci., 4th ser., vol. 2, 1896, p. 123 et seq.; vol. 3, 1897, p. 75. 4 S. L. Penfield and G. S. Jamieson, idem, vol. 20, 1905, p. 217. The authors prepared tychite synthet- ically. Both northupite and tychite have also been made artificially by A. B. de Schulten, Bull. Soc. Min., vol. 19, 1896, p. 164, and Compt. Rend., vol. 143, 1906, p. 403. The relations between the two species are perhaps more clearly expressed by formulae of the following type: Tychite 2 MgC 03 . 2 Na 2 C 03 .Na 2 S 0 <. N orthupite 2MgC O 3 . 2N a 2 CC> 3 . 2 N aCl . On gaylussite and pirssonite, see R. Wegscheider and H. Walter, Monatsh. Chemie, vol. 28, 1907, p. 633. 6 E. S. Larsen and W. B. Hicks, Am. Jour. Sci., 4th ser., vol. 38, 1914, p. 437. Searlesite is peculiarly interesting as the first known example of an alkaline borosilicate. e For a full description of the minerals of Searles’s marsh, see H. S. Gale and W. T. Schaller, Bull. U. S. Geol. Survey No. 580, 1914, pp. 296-308. On pp. 276 and 277 Gale cites analyses of the brine of the marsh or “lake.” 248 THE DATA OF GEOCHEMISTRY. About 12 miles north of Daggett, in the southern part of San Bernardino County, a still different borate deposit is found. 1 Here, interstratified with lake sediments, a solid bed of colemanite exists, which ranges from 5 to 30 feet in thickness and is highly crystalline. At one end the colemanite is much mixed with sand, gypsum, and clay, suggesting that it had been laid down at the edge of an evapo- rating sheet of water. Campbell regards the borax of the Amargosa marshes as probably derived from the leaching of deposits simi- lar to this. H. S. Gale, 2 however, who has more recently studied the colemanite, regards it as a vein mineral. From another point in the Mohave Desert a mineral has been re- ported 3 (bakerite), having the empirical formula 8Ca0.5B 2 0 3 .6Si0 2 . 6H 2 0; but its definite character is yet to be ascertained. Priceite, which is probably a massive form of colemanite, is found in Curry County, Oregon, on the shore of the Pacific. It occurs in com- pact nodules, from the size of an egg up to several tons in weight, associated with serpentine. 4 Pandermite, another variety of the same species, from near Panderma, on the Sea of Marmora, also forms nodules, but in a bed underlying a thick stratum of gypsum. Colemanite and its modifications, then, exist under a variety of dif- ferent conditions, and we can not say that it has always been pro- duced in the same way. It is stated by Campbell, 5 however, that the lake-bed deposits of California were probably laid down during a period of volcanic activity. Both colemanite and pandermite have been prepared artificially by J. H. Van’t Hoff, 6 who acted on ulexite (boronatrocalcite) with saturated solutions of alkaline chlorides. With a solution of sodium and potassium chlorides at 110° pandermite was formed to which Van’t Hoff assigns the formula Ca 8 B 20 O 38 .15H 2 O. Colemanite, Ca 2 B 6 O n . 5H 2 0, forms from ulexite in a sodium chloride solution most readily at 70°. Van’t Hoff, it will be noticed, does not regard pandermite and colemanite as identical. Immediately south of Lake Alvord, in Harney County, Oregon, an extensive marsh is covered by an incrustation containing borax, salt, sodium sulphate, and sodium carbonate in varying proportions. 7 This locality has been worked for borax, and the deposit is said to be continually reproduced. The region calls for more complete exami- nation, especially on the chemical side. 1 See M. R. Campbell, Bull. U. S. Geol. Survey No. 200, and W. H. Storms, Eleventh Ann. Rept. Cal- ifornia State Mining Bureau, 1893, p. 345. 2 Prof. Paper U. S. Geol. Survey No. 85, 1913, p. 3. 3 W. B. Giles, Mineralog. Mag., vol. 13, 1903, p. 353. * Information received from J. S. Diller, who has examined the locality. b Eng. and Min. Jour., vol. 74, 1902, p. 517. e Sitzungsb. Akad. Berlin, vol. 39, 190G, pp. 566, 689. i W. D. Dennis, Eng. and Min. Jour., vol. 73, 1902, p. 581. SALINE RESIDUES. 249 In the arid region of southern California beds containing sodium nitrate are found near the borate deposits. The same association, if we can justly call it so, also exists in South America, where the soda niter of the Tarapaca and Atacama deserts is accompanied, more or less closely, by ulexite. As early as 1844 A. A. Hayes 1 described the calcium borate from near Iquique, and noted its association with glauberite, gypsum, pickeringite, and a native iodate of sodium. D. Forbes, 2 describing more fully the salines of this region, which he regarded as post-Tertiary, added salt, epsomite, mirabilite, thenardite, glauberite, soda alum, anhydrite, soda niter, and borax to the list of species. The salines themselves Forbes attributed to the concentra- tion of sea water, but the borates were, he believed, of volcanic origin. They occur in the more elevated parts of the saline region, in which he found -active fumaroles; but the latter were not examined for boron. Later 3 he was able to confirm this view by finding a calcium borate, either ulexite or bechilite, actually in process of deposition at the hot springs of Banos del Toro, in the Cordilleras of Coquimbo. L. Darapsky, in his work on the Taltal district, 4 speaks of ulexite as a regular companion of the nitrates, and especially notes the presence of borates in the waters of a lagoon at Maricunga. The borax “lake ” of Ascotan, according to R. T. Chamberlin, 5 derives its borates, mainly ulexite, from leachings from adjacent volcanoes. Farther east, in Argentina, several borate localities are known. J. J. Kyle 6 describes ulexite, associated with glauberite, from the Province of Salta, and refers to its existence in Catamarca. It is also found at Safinas Grandes, Province of Jujuy, according to H. Butt- genbach, 7 who describes the occurrence in some detail. The center of the deposit is covered with rock salt 20 to 30 centimeters in thick- ness, and around its borders the ulexite nodules are unevenly dis- tributed. Gypsum, soda niter, glauberite, and pickeringite are also found with it, the gypsum predominating. Boracite and carnallite are absent. The locality is overflowed in spring by water from the mountains, but is dry in summer, and Buttgenbach expresses the opinion that ulexite is produced every year at flood time. It will be remembered that this same phenomenon of growth was noted in connection with the Nevada mineral. The boric acid of the ulexite 1 Am. Jour. Sci., 1st ser., vol. 47, 1844, p. 215. 2 Quart. Jour. Geol. Soc. London, vol. 17, 1861, p. 7. 3 Philos. Mag., 4th ser., vol. 25, 1863, p. 113. 4 Das Departement Taltal (Chile), Berlin, 1900. See especially pp. 149, 150, 163. An abstract is printed in Zeitschr. prakt. Geologic, 1902, p. 153. 5 Jour. Geology, vol. 20, p. 763, 1912. 6 Anales Soc. cient. Argentina, vol. 10, 1880, p. 169. 7 Annales Soc. gdol. Belgique, vol. 28, M, 1900-1901, p. 99. Analyses of the ulexite are given. 250 THE DATA OF GEOCHEMISTRY. is regarded by Buttgenbach as being of volcanic origin. 1 The same view is held by A. Jockamowitz 2 with regard to the ulexite of the Salinas Lagoon, Province of Arequipa, Peru. The old localities for borax in Tibet and the adjacent regions have been little visited by Europeans, and detailed information concerning them is very scanty. H. von Schlagintweit, 3 however, has described the great borax deposits of the Puga Valley, in Ladak, where the min- eral covers the ground over a large area to an average depth of 3 feet. The borax is a deposit from hot springs, which issue more than 15,000 feet above sea level, at a temperature ranging from 54° to 58° C. The saline mass also contains free boric acid and sulphur, with less salt, ammonium chloride, magnesium sulphate, and alum, and there is much gypsum in its vicinity. No ulexite was found. On the peninsula of Kertch, near the Sea of Azov, borax occurs among the erupted substances of the so-called “mud volcanoes.” 4 It effloresces upon the surface of the dried mud, and is more or less mixed with salt and soda. Since borates are present in sea water, it follows that they must also occur among the products of its evaporation. This conclusion is best verified at Stassfurt, where the following species are found: 5 Boracite Mg 7 Cl 2 B 16 O 30 . . Pinnoite MgB 2 0 4 .3H 2 0. Ascharite 3Mg 2 B 2 0 5 . 2H 2 0 . Heintzite K 2 Mg 4 B 22 0 38 . 14H 2 0 . Hydroboracite (?) CaMgB 6 0 n .6H 2 0. Sulphoborite 2MgS0 4 .4MgHB0 3 . 7 H 2 0 . Of these species, hydroboracite is found in the lower deposits at Stassfurt, 6 associated with anhydrite; the others are characteristic of the carnallite zone. That is, they are mother liquor salts, and among the latest substances to crystallize. It is also to be noted that they are essentially magnesian borates, and that calcium, which is the dominant metal in the Chilean and Californian localities, occurs in only one of the StassfuFt species. This is what we should expect from sea water, in which magnesium is abundant and calcium relatively subordinate. In any general discussion of the genesis of borates this distinction must be borne in mind. 7 1 In Chem. Zeitung, vol. 30, 1906, p. 150, F. Reichert describes eight of the Argentine “borateras” and gives analyses of their products. His complete report, Los yacimientos de boratos, etc., is in Anales del Ministerio de agricultura, Buenos Aires, 1907. For an abstract, see Zeitschr. Kryst. Min., vol. 47, 1909, p. 205. 2 Bol. Cuerpo ing. minas, Peru, No. 49, 1907. 3 Sitzungsb. Acad. Munchen, vol. 8, 1878, p. 518. 4 W. S. Vernadsky and S. P. Popoflf, Zeitschr. prakt. Geologie, 1902, p. 79. 5 Liineburgite, a magnesium borophosphate found with the potash salts of Liineburg, Hannover, may fairly be included with this list. 6 In his paper on the borates of the German potash salts, H. E. Boeke (Centralbl. Min., Geol. u. Pal., 1910, p. 531) does not mention hydroboracite. Its identification is, perhaps, not quite certain. ' See also W. Biltz and E. Marcus (Zeitschr. anorg. Ohemie,'vol. 72, 1911, p. 302) on the borates of Stassfurt. SALINE RESIDUES. 251 In the gypsum beds of Nova Scotia ulexite, howlite, and crypto- morphite are found, associated with anhydrite, selenite, mirabilite, salt, aragonite, and calcite. 1 Howlite is represented by the formula H 5 CaB 2 Si0 14 ; cryptomorphite 2 is probably H 2 Na 4 Ca 6 (B 4 0 7 ) 9 .22H 2 0. If this gypsum is, as most authorities assume, a marine deposit, these salts occupy a position similar to that filled by hydroboracite at Stassfurt, but the total absence of magnesium is rather striking. 3 In order to account for the origin of boric acid and saline borates, three hypotheses have been proposed and strenuously advocated. First, they may be derived from the leaching of rocks containing borosilicates, such as tourmaline, axinite, dumortierite, danburite, and datolite. Second, they are supposed to be of volcanic origin. Third, they are regarded as marine deposits. Probably each mode of derivation is represented by actual occurrences in nature, as may be judged from the evidence brought forward in the preceding pages, but the first supposition has not been directly tested at any known locality. Many rocks, especially granites and mica schists, contain tourmaline; they undergo decomposition, and boric acid is washed away; but borates from that source have not been found to accumu- late in any known saline residue. They may do so, but they have not been directly traced. If, however, it could be shown that volcanic borates came from the thermal metamorphism of tourmaline-bearing rocks, the first and second hypotheses might be partly unified. Even then the question of the formation of soluble borates by weathering would be untouched. The volcanic theory seems to fit a considerable number of borate localities, although its application to some cases may have been forced, and for others its validity has been doubted. Several writers have denied the volcanic character of the Tuscan fumaroles, despite the thermal activity of the region and the presence in it of eruptive rocks. 4 That boric acid is emitted from volcanic vents is, however, unquestionable. It is there associated with ammonium salts precisely as it is at Monte Cerboli — an association which can not be overlooked or disregarded. The marine origm of borates is most evident at Stassfurt, although even here their presence has been attributed to the injection of vol- canic gases. Here, however, and also in the gypsum beds of Nova Scotia the nitrogen compounds are lacking, a clear distinction from the presumably volcanic occurrences. At Stassfurt the volcanic 1 See H. How, Am. Jour. Sci., 2d ser., vol. 32, 1861, p. 9; Philos. Mag., 4th ser., vol. 35, 1868, p. 31; vol.41, 1871, p. 270. 2 Calculated by F. W. Clarke from How’s analysis. 3 The suggestion of J. W. Dawson (Acadian geology, 1891, p. 262) that these enormous masses of gypsum were produced by the action of acid volcanic waters on limestone is of doubtful significance. The region, however, contains eruptive rocks in great abundance, a fact which may partly justify the speculation. * See, for example, a letter from W. P. Jervis, published by H. G. Hanks in Third Ann. Rept. State Min- eralogist California, 1883, p. 68; also L. Dieulafait, Compt. Rend., vol. 100, 1885, p. 1240. 252 THE DATA OF GEOCHEMISTRY. hypothesis seems to be quite superfluous, and the derivation of all the saline substances which there coexist can be most easily ex- plained as due to the concentration of sea water. The existence of borates in the latter is clearly established; but whence were they derived ? Any answer to that question must be purely speculative. Whether we invoke the aid of submarine volcanoes or attribute our borates to leachings from the land, we go beyond the limits of our knowledge and remain unsatisfied. Confining ourselves, then, to considerations of a proximate char- acter, we may fairly assert that certain borate localities are of volcanic and others of oceanic origin. Nevertheless, attempts have been made to explain all these deposits by the marine hypothesis, as in the memoirs of C. Ochsenius 1 and L. Dieulafait . 2 Dieulafait tries to prove that all saline deposits are primarily derived from sea water, in either ancient or modern times, and even the Tuscan “soffioni” are supposed by him to draw their boric acid from subterranean salif- erous sediments. Mother liquors, rich in magnesium chloride and heated by steam, are thought to liberate hydrochloric acid, which, acting upon the magnesium borates, sets boric acid free, to be carried upward by the escaping vapors. These reactions are possible, but it is not proved that they have actually occurred. Ochsenius also argues in much the same way, and points out that beds of rock salt exist at no very great distance from the region of fumaroles. Their mother liquors are to his mind the source of the boric acid. If we turn to the ulexite and colemanite beds of California and Chile, we find a distinct set of phenomena to be interpreted. Here we deal undoubtedly with ancient lake beds, but the residues contain calcium, not magnesium borate. Some of the deposits are below sea level, as at Death Valley; others are thousands of feet above, as at Maricunga; and in or near all of them nitrates are also found. Hot springs are common in both regions, in California as well as in Chile; but they have not been exhaustively studied. Do they contain boric acid and ammonia ? If so, did the lake beds derive their nitrates from such sources ? These questions are legitimate ones for future investi- gators to answer, and the replies may help to solve the problem now before us. Ammonia, by oxidation, yields nitric acid — a reaction which has been studied exhaustively in the interests of agriculture. Forbes found a calcium borate forming in a Chilean hot spring . 3 Magnesium borates do not occur in either group of localities. From these facts we see that a volcanic origin is conceivable for the deposits in question, whereas a marine source is not at all clearly indicated. 1 Zeitschr. prakt. Geologie, 1893, pp. 189, 217. Borates especially on pp. 222, 223. 2 Annales chim. phys., 5th ser., vol. 12, 1877, p. 318; vol. 25, 1882, p. 145. Also Compt. Rend., vol. 85, 1877, p. 605; vol. 94, 1882, p. 1352; vol. 100, 1885, pp. 1017, 1240. 3 Some of the Chilean thermal waters, analyzed by P. Martens (Actes Soc. sci. Chili, vol. 7, 1897, p. 311), contain both borates and ammonium salts, but not in remarkable proportions. SALINE RESIDUES. 253 Neither hypothesis can be adopted with any degree of assurance; but the volcanic theory is the more plausible of the two. As we pass on to the study of the nitrate beds, these suggestions may become a little clearer. For the moment the following summary may serve to assist future discussion: (1) Marine deposits contain magnesium borates. (2) Lake-bed deposits contain calcium borates, with nitrates near by. (3) Volcanic waters and fumaroles, when they yield borates, yield ammonium compounds also. NITRATES. Nitrates are commonly formed in soils by the oxidation of organic matter, a process in which the nitrifying micro-organisms play an important part. 1 In moist climates these salts remain in the ground water, are consumed by growing plants, or are washed away; in arid or protected regions they may accumulate to a considerable extent. Some nitrates are also derived from atmospheric sources, the acid being formed by electrical discharges and brought down by rain, but their amount is probably only a small portion of the entire product. Wherever organic matter putrefies in contact with alkaline materials, such as lime or wood ashes, nitrates- are produced — a process which has been carried on artificially in various countries in order to supply the industrial demand for saltpeter. In sheltered places, such as caverns, calcium nitrate is often produced in large quantities, and its formation has commonly been attributed to the nitrification of bat guano. 2 This supposition, however, may not cover all cases, for W. H. Hess 3 claims that nitrates are uniformly distributed over cave floors in Kentucky and Indiana, even in the remote interiors of cav- erns where no guano exists. In drippings from the roof of the Mam- moth Cave he found 5.71 milligrams per liter of N 2 0 5 , whose source he ascribes to percolating waters from outside. The cave, in his opinion, acts as a receptacle for stopping a part of the surface drain- age, in which nitrates are produced in the usual way. Earth gathered far within the cavern contains nitrates, but almost no organic matter. The deposits of potassium nitrate found in Hungary are traced by 1 See for example W. P. Headden (Proc. Colorado Sci. Soc., vol. 10, 1911, p. 99), on unusual accumula- tions of nitrates in certain Colorado soils. He cites other literature. 2 See A. Muntz and V. Marcano, Ann. chim. phys., 6th ser., vol. 10, 1887, p. 550, on cave earth from Vene- zuela. For an account of saltpeter earth in Turkestan see N. Ljubavin, Jour. Chem. Soc., vol. 48, 1885, p. 128. On nitrate earth at Tacunga, Ecuador, see J. B. Boussingault, Annales chim. phys., 4th ser., vol. 7, 1866, p. 358, followed by a letter from Chabrid on Algerian saltpeter. M. Glasenapp (Ann. Geol. Min. Russie, vol. 12, 1910, p. 42, abstract) describes an impregnation of potassium nitrate in the Senonian sand- stones of the Caucasus. 3 Join-. Geology, vol. 8, 1900, p. 129. The views advanced by Hess have been disputed by H. W. Nichols (Jour. Geology, vol. 9, 1901, p. 236), who regards guano as the chief source of cave nitrates. 254 THE DATA OF GEOCHEMISTRY. C. Ochsenius 1 to the mother liquors of sea water, their potassium chloride being first transformed to carbonate, which latter is then nitrified in presence of organic substances. In this suggestion the hypothetical element is rather large, although it is plausibly defended. We have already noticed the existence of soda niter among the min- erals of Searles’s marsh, and its probable association with ammonium compounds. The same substance is also reported to occur in large quantities at various other points in southern California, especially around Death Valley and along the boundary between Inyo and San Bernardino counties. 2 It is said to form beds associated with the later Eocene clays, and in some cases to impregnate the latter; but its direct conjunction with borates is not positively asserted, except in the locality at Searles’s marsh. The fact that soda niter exists in the same region with the borates is important, however, for it correlates the California deposits with the Chilean beds, where a similar relationship is recognized. According to Bailey, 3 the rare species darapskite and nitroglauberite, previously known only from Chile, are also found in the nitrate beds of California. In the deserts of Atacama and Tarapaca, in the northern part of Chile, 4 are found the largest known deposits of nitrates in the world. The crude sodium nitrate is termed locally “caliche,” and the “cali- cheras” are scattered over a large area which also contains beds of salt, “salares,” and the deposits of ulexite which we have already considered. According to V. L’Olivier, 5 the nitrates were first de- posited, then the salt, generally to the westward of the calicheras, and finally the borates, which lie more to the east and in the higher levels of the evaporation basins. Some ulexite, however, is found in the nitrate beds. A characteristic calichera, in the Atacama Desert, 50 miles west of Taltal, is described by J. Buchanan 6 as being made up of the following layers : 1 Zeitschr. prakt. Geologie, 1893, p. 60. 2 G. E. Bailey, Bull. No. 24, California State Mining Bureau, 1902, pp. 139-188. 3 Op. cit., p. 170. * The region was formerly a part of Peru and Bolivia. s Annales chim. phys., 5th ser., vol. 7, 1876, p. 289. For other details see D. Forbes, Quart. Jour. GeoL Soc., vol. 17, 1861, p. 7; C. Ochsenius, Zeitschr. Deutsch. geol. Gesell., 1888, p. 153; and L. Darapsky, Das Departement Taltal (Chile), Berlin, 1900. See also A. Pissis, Nitrate and guano deposits in the Desert of Atacama, London, 1878, published by authority of the Chilean Government. An earlier description of the nitrate field by J. W. Flagg is given in Am. Chemist, vol. 4, 1874, p. 403; and there is a recent important memoir by Semper and Michels, Zeitschr. Berg-, Hiitten- u. Salinenwesen preuss. St., 1904, pp. 359-482, See also W. S. Tower, Min. and Sci. Press, vol. 107, 1913, p. 496, and W. H. Ross, Pop. Sci. Monthly, vol. 85, 1914, p. 134. 6 Jour. Soc. Chem. Ind., vol. 12, 1893, p. 128. See also B. Simmersbach and F. Mayr, Zeitschr. prakt. Geologie, 1904, p. 273. SALINE RESIDUES. 255 Section of typical calichera in Atacama Desert , Chile. Ft. in. 1. Sand and gravel 1-2 2. “Chusca,” a porous, earthy gypsum 6 3. A compact mass of earth and stones 2-10 4. “Costra,” a low-grade caliche, containing much sodium chloride, feldspar, and earthy matter 1-3 5. “ Caliche.’’ (In the Tarapaca Desert it is from 4 to 12 feet thick) 14-2 6. “Coba,” a clay ±3 The costra contains a considerable amount of bloedite; the rarer minerals, to be mentioned presently, are found in the caliche. The composition of the caliche is very variable, as the following analyses, cited by R. A. F. Penrose, jr., show. 1 Analyses of caliche. A B c D E F G NaN0 3 28. 54 53. 50 41. 12 61. 97 22. 73 24. 90 27. 08 kno 3 Trace. 17. 25 3. 43 5.15 1. 65 2. 50 1. 34 NaCl 17. 20 21. 28 3. 58 27. 55 41. 90 24. 50 8. 95 CaCl 2 5. 25 MrCI,.* . 18 KC10 4 Trace. .78 .75 .21 Trace. Trace. Trace. Na 2 3 0 4 5. 40 1. 93 Trace. 2. 13 .94 6. 50 None. MgS0 4 3. 43 1. 35 10. 05 .15 3. 13 6. 50 None. CaS0 4 2. 67 .48 3. 86 .41 4. 80 4. 50 2. 89 Na 2 B 4 0 7 .49 .56 .20 .43 .53 .15 .52 Nal . 047 NaI0 3 .043 .01 .05 .94 .07 .054 .08 NH 4 salts Trace. Trace. Trace. Trace. Trace. Trace. Trace. Na 2 Cr0 4 Trace. Trace. Trace. Insoluble 40. 30 2. 07 31.86 .39 22. 50 28. 40 47. 34 H 2 0, combined, etc.. 1. 88 .79 5. 00 .67 1. 75 2. 00 6. 37 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Anhydrite, gypsum, thenardite, mirabilite, bloedite, epsomite, glauberite, and salt are associated with the nitrates, and also the four following more unusual species : Darapskite NaNO s . N a 2 S0 4 .H 2 0 . N itroglauberite 6NaN0 3 . 2N a 2 S0 4 .3H 2 0 . Lautarite Cal 2 0 6 . Dietzeite 7CaI 2 0 6 .8CaCr0 4 . The lautarite and dietzeite are remarkable as the first definitely known iodates to be found in the mineral kingdom, although A. A. Hayes 2 reported sodium iodate as long ago as 1844. In dietzeite we have a compound of iodate and chromate which is analogous to 1 Jour. Geology, vol. 18, 1910, p. 14; D. G. Buchanan, analyst. F.or other analyses see L. Darapslcy, Das Departement Taltal, Berlin, 1900; A. Zillaruello, Anales. Soc. cient. Argentina, vol. 68, p. 20; and F, W. Dafcrt. Monatsh. Chem., vol. 29, 1908, p. 235. 2 See ante, p. 249. 256 THE DATA OF GEOCHEMISTRY. some artificial salts but whose origin it is difficult to understand. Bromine is generally believed to be absent from nitrate beds, but A. Muntz 1 claims to have found it, in the form of bromates, in the mother liquors from which the saltpeter had crystallized out. Fur- thermore, in recent years considerable quantities of perchlorates, running in exceptional cases as high as 6.79 per cent of KC10 4 , have been discovered in Chilean nitrates. 2 Finally, these nitrates always •contain some borates, perceptible traces of rubidium and lithium, but probably no caesium. 3 The borates may be small in amount, but it is doubtful whether they are ever quite absent. The nitrate beds of South America are not entirely confined to Chile, although the Chilean deposits outrank all others in impor- tance. The locality at Salinas Grandes, Argentina, has already been noticed in connection with its borates, and the niter there seems to be in entirely subordinate quantities. In the Argentine Territory of Santiago del Estero, according to W. F. Reid, 4 there are salines which form crusts of salt during summer; and in the centers of the lagoons mother liquors exist from which sodium nitrate is obtained. Zaracristi 5 has described another occurrence in the valley of the river San Sebastiano, in Colombia, where beds of sodium nitrate overlie a mixture of gypsum and calcareous clay, containing some oxide of iron and common salt. This deposit is very impure. An immense deposit of potassium nitrate, according to F. Sacc, 6 exists near Cochabamba, Bolivia, in direct association with borax. Sacc’s analysis of a sample from this locality gives the following percentage composition of the salts: Analysis of nitrate deposits near Cochabamba , Bolivia. KNO s 60.70 N^B.Oy 30.70 NaCl Trace. H 2 0 Trace. Organic matter 8. 60 100. 00 The soil below the layer also contains borax. Sacc attributes the nitrates to the oxidation of ammonium salts in the soil. The associa- tion of borates with potassium nitrate is especially noteworthy, and the locality ought to receive a more detailed examination. 1 Annales chim. phys., 6th ser., vol. 11, 1887, p. 121. 2 B. Sjollema, Chem. Zeitung, vol. 20, 1896, p. 1002. As the perchlorates are believed to injure the nitrate as a fertilizer, a voluminous discussion over their detection and effects has appeared in the agricultural journals. 3 L. Dieulafait, Compt. Rend., vol. 98, 1884, p. 1545. « Jour. Soc. Chem. Ind., vol. 19, 1900, p. 414. 5 Berg. u. Hvittenm. Zeitung, vol. 55, 1896, p. 391. Two analyses are given. 6 Compt. Rend., vol. 99, 1884, p. 84. SALINE RESIDUES. 257 No satisfactory explanation of the nitrate beds has yet been found, although many theories have been proposed to account for them. In addition to that of Forbes, already cited in relation to the borates, the following discussions of the subject are worth considering. C. Noellner, 1 who assumed a marine origin for the deposits, suggested that their nitrogen might be derived from decomposition of great masses of seaweeds ; but this view has not been generally accepted. For example, the beds at Maricunga 2 are 3,800 meters above sea level and 180 miles from the coast, and other localities present similar difficulties of distance and elevation. The plain of Tamarugal, studied by W. Newton, 3 lies between the coast range and the Andes, 3,000 feet above the sea, and the nitrate beds have peculiarities which seem to preclude either an oceanic origin or a derivation from guano. Here, at least, bromides are absent, and only traces of phosphates can be found. Sea water would yield the former; from guano the latter would remain. Newton regards the nitrates as originally formed by the oxidation of organic matter in alluvial soil. Tropical floods, which cover the plain once in every seven or eight years, bring upon it the concentrated fertility of thousands of square miles and sweep the deposits to the landward side of the coast chain, where they are mainly found. This is Newton’s view, although he admits the possi- bility that electrically generated atmospheric nitrates may also be present. The same possibility is recognized by Semper and Blancken- horn, but rejected by A. Muntz, 4 who regards the electrical source as quite inadequate. Muntz accepts an organic origin for the nitrates, and argues that the calcium salt was first formed, as in the ordinary artificial process of nitrification. That compound then reacts with sodium chloride, forming calcium chloride and sodium nitrate, a transformation which he effected experimentally. The same result was also obtained later by A. Gautier, 5 who finds in guano the source of the nitrogen. The reaction is further suggested by the facts that the Chilean niter is always associated with salt, and that calcium chloride is found in the underground waters of the Pampas. Muntz also proved, by direct experiment, that iodides in a nitrifying mix- ture were oxidized to iodates; and from the absence of phosphates in the nitrate beds he infers that the nitrates have been transported in solution and redeposited at a distance from the original seat of their formation. 1 Jour, prakt. Chemie, vol. 102, 1867, p. 459. 2 See E. Semper and M. Blanckenhorn, Zeitschr. prakt. Geologie, 1903, p. 309. s Jour. Soc. Chem. Ind., vol. 19, 1900, p. 408. See also an earlier paper in Geol. Mag., 1896, p. 339. 4 Annales chim. phys., 6th ser., vol. 11, 1887, p. 111. 6 Annales des mines, 9th ser., vol. 5, 1894, p. 50. 97270°— Bull. 616—16 17 258 THE DATA OF GEOCHEMISTRY. C. Ochsenius , 1 who has written voluminously on the Chilean nitrates, regards them as derived from the mother liquors of salt deposits in the Andes. These are supposed to flow downward to the plains, their chlorides being partly converted to carbonates by car- bonic acid of volcanic origin. The nitrogen is brought as ammoniacal dust from guano beds upon or near the seacoast, the heavier phos- phatic particles being left behind. That such dust is carried by the winds is certain; but is it carried in sufficient amounts to account for large nitrate deposits far inland ? Another difficulty is suggested by Darapsky, who points out in his work on Taltal the comparative scarcity of carbonates in the nitrate regions. Even the waters of the Pampas contain little carbonic acid, and among the mineral springs of Chile and Argentina carbonated waters are the exception rather than the rule. Penrose , 2 in his recent study of the nitrates, favors a marine origin for them, on the ground that the pampa, where the nitrate deposits occur, was once a part of the ocean bottom. Their nitrogen he derives from guano, and their iodine either from decomposing sea- weeds or from mineral springs. The borates he ascribes to the decomposition of rocks containing boron-bearing minerals. The absence of bromides and the occurrence of nitrates at great eleva- tions he does not try to explain. That the nitrate beds are proximately derived from the evapora- tion of saline waters is beyond doubt, but their marine origin, in light of what has been said, seems to be questionable. The ultimate source of their nitrogen is a more troublesome question and remains, so far, unsolved. The weight of opinion favors a derivation from organic matter, and from this point of view, Newton’s explanation of the deposits is as satisfactory as any. Explanations of this order, however, are incomplete, for they take no account of the remarkable association of boron and nitrogen. Why do borates and ammonia occur together in volcanic waters, or borates and nitrates in the deposits of both Chile and California ? This fact, which has already been emphasized, is surely not without significance, and it legitimizes the suspicion that the nitrates may be partly derived from volcanic sources. To be sure, this is only a suspicion, but it is one which ought not to be left out of account. Hot springs are common in the deserts of California and Nevada; they are also found along the volcanic Andean chain; do they contain boron and ammonia as a general rule, or only in sporadic instances ? Such waters, collecting in lagoons in the presence of some organic matter and the nitrifying 1 Zeitschr. prakt. Geologie, 1893, p. 217; 1901, p. 237; 1904, p. 242. Zeitsehr. Deutsch.geol. Gesell.,1888, p. 153. Ochsenius’s work, Die Bildung des Natronsalpeters aus Mutterlaugensalzen, Stuttgart, 1887,1 have not been able to see. His controversial papers, cited above, give a complete exposition of his views. 2 Jour. Geology, vol. 18, 1910, p. 16. SALINE RESIDUES. 259 organisms, would yield nitrates, and the latter would be found in the dried residues. A careful examination of all hot springs existing in the vicinity of nitrate beds is needed before we can decide how much weight can be given to this volcanic hypothesis . 1 It may be discarded, but it should at least be thoroughly investigated. THE ALUMS. One more class of saline residues remains to be mentioned. Waters containing sulphates of iron or aluminum form deposits of these salts, which may be neutral or basic, simple or complex. Their for- mation, however, is very local, and compounds of this character are rarely found far from their points of origin. They are commonly derived, directly or indirectly, from the oxida- tion of sulphides, and occur as incrustations or even as stalactites, around mineral springs, or in the shafts or tunnels of mines. Acid solutions, produced by the oxidation of pyrite, act upon aluminous rocks and form sulphates of alumina. Alunite and alunogen are among the commoner species so generated. Alunogen and halotri- chite, the latter a sulphate of aluminum and iron, are found in large quantities in Grant County, N. Mex . 2 Sulphates of iron of numer- ous species are especially abundant in the arid region of Chile. Sulphates of zinc, copper, cobalt, and nickel are deposited by mine waters. Some of the species thus developed will be considered in subsequent chapters, either in relation to the decomposition of rocks or in connection with the study of metallic ores. 1 According to T. Van Wagenen (Min. and Sci. Press, vol. 84, 1902, p. 63), sodium nitrate is found in and around an extinct hot spring at the foot of the Humboldt Sink, Humboldt County, Nev. 2 See C. W. Hayes, Bull. U. S. Geol. Survey No. 315, 1907, p. 215. On alunogen in Colorado see W. P. Headden, Proc. Colorado Sci. Soc., vol. 8, 1905, p. 62; also P. Termier on the derivation of alunite from feldspar, Bull. Soc. min., vol. 31, 1908, p. 215. W. Cross, Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1896, p. 314, and H. W.Turner, Am. Jour. Sci., 4th ser., vol. 5, 1898, p. 424, have described quartz-alunite rocks. On alunite in ore bodies see F. L. Ransome , Econ. Geology, vol. 2, 1907, p. 667. These occurrences are products of rock decomposition rather than residues from saline waters. On the remarkable vein of alunite at Marysvale, Utah, see B. S. Butler and H. S. Gale, Bull. U. S. Geol. Survey No. 511, 1912. CHAPTER VIII. VOLCANIC GASES AND SUBLIMATES. GASEOUS EMANATIONS. Regardless of all speculations as to the origin of the lithosphere or as to the nature of the earth’s interior, we must recognize the fact that some rocks were formed by the cooling of molten materials, and we can study the phenomena of their development quite independ- ently of cosmogonic hypotheses. Fluid magmas are seen to issue from the earth and to solidify as lavas; they may be emitted quietly or with explosive violence, and they are accompanied by gaseous or vaporous emanations, which either escape into the air, are partially occluded by the cooling mass, or condense in the form of water. Gases, water, mud, and fused or incandescent rocks are thrown out by volcanoes, and many of the attendant phenomena can be directly observed, or even reproduced in the laboratory. To the geophysicist the nature of the volcanic forces is a prime subject of interest; chem- istry concerns itself more with the nature of the products, and the latter theme is the one which demands attention now. During a volcanic eruption the gaseous emanations are the first to appear, and their evolution continues more or less conspicuously until the discharge ends. Their emission does not cease even then, for gases are given off from the cooling lavas, and also from the hot springs and solfataras which are formed in the course of the out- break. These gases vary much in character, and in a single eruption they may present great differences in composition, changing from place to place and from time to time. For analysis they are com- monly drawn from vents, crevices, or fumaroles at different dis- tances from the center of activity, for the main crater itself is rarely accessible until after the eruptions have ceased. Furthermore, it is difficult to collect the gases quite free from admixtures of atmos- pheric air, and the samples analyzed are therefore, as a rule, impure. Still much is known concerning them, and many analyses of these exhalations have been recorded. It has long been held by nearly all authorities that water vapor or steam is the most abundant of the volcanic gases. The statement is generally accepted that it forms as much as 99 per cent of the entire gaseous output, but it soon condenses to liquid and is added or restored to the hydrosphere. For instance, F. Fouque, 1 observing i See A. Geikie, Textbook of geology, 4th ed., p. 266. I have not been able to find the original source of this citation. 260 VOLCANIC GASES AND SUBLIMATES. 261 one of the many parasitic cones on Etna, estimated that in one hun- dred days it discharged vapor equivalent to 2,100,000 cubic meters of water, or 462,000,000 imperial gallons. This great quantity is only a small fraction of what the entire volcano must have annually emitted and its proximate origin may well be a subject for specula- tion. Is the water originally magmatic or only of surface origin; truly essential or merely extraneous ? On this scheme there is active controversy, which will be considered in due order later. The other volcanic gases, the term “gas” being used in its ordi- nary significance, are hydrogen, oxygen, nitrogen, argon, helium, hydrogen sulphide, sulphur dioxide, carbon dioxide, carbon monoxide, hydrochloric acid, chlorine, methane, hydrofluoric acid, and silicon fluoride. 1 Many other substances are found among volcanic exhala- tions and are deposited as sublimates around vents and fumaroles. Let us first consider the composition of the true gases, noting in advance that they were dried before analysis in order to eliminate the excess of water. It is not necessary for our purposes to go any farther back in time than to the middle of the last century, when R. W. Bunsen published the results of his Icelandic researches. 2 From among his analyses of volcanic gases the following examples are selected: Analyses of volcanic gases from Iceland. A. From a fumarole in the great crater of Hekla. B. From a fumarole in the lava of 1845, Hekla. C. From the solfatara of Krisuvik. D. From a fumarole a quarter of a league distant from Krisuvik. E. From a group of fumaroles at Reykjalidh, in the extreme north of Iceland. A B C D E n 2 81.81 78.90 1.67 0.50 0.72 Oo 14.21 20.09 Ho 4.30 4.72 25. 14 C0 2 2.44 1.01 87.43 79.07 50.00 H 2 S None . 6.60 15.71 24. 12 S0 2 1.54 100. 00 100. 00 100. 00 100.00 99. 98 1 The two fluorine compounds are reported by A. Scacchi from Vesuvius, Catalogo dei minerali Vesu- viani, Naples, 1887. See also E. S. Dana, System of mineralogy, 6th ed., p. 169. According to A. Gautier, (Compt. Rend., vol. 157, 1913, p. 820) volcanic gases generally contain fluorine compounds. In a gas from Vesuvius he found 0.110 milligram of F per l'ter. In a sublimate from the volcano Chinyero, Canary Islands, A. del Campo (Jour. Chem. Soc., vol. 104, ii, 1913, p. 145) found ammonium fluoride. * Annales chim. phys., 3d ser., vol. 38, 1853, p. 215. For these analyses and others, see pp. 260-266. An earlier, classical memoir by Eliede Beaumont, entitled “Emanations volcaniques et metalliferes,” appeared in Bull. Soc. geol. France, 2d ser., vol. 4, 1847, p. 1249. An important article on the gases of the hot springs of Iceland and their radioactivity, by T. Thorkelsson, is in the Memoirs of the Danish Acad., 7th ser., vol. 8, 1910, p. 181. 262 The data of geochemistry. The water condensed from the fumaroles of Hekla carried a little hydrochloric acid, but in amounts too small for determination. Among the sublimates formed by these fumaroles, Bunsen noted sulphur and various metallic chlorides, especially common salt. One sublimate, however, contained 81.68 per cent of ammonium chloride. Because of their accessibility the Italian volcanoes have been studied with peculiar thoroughness, and with regard to their gaseous exhalations the data are most abundant. In 1856 C. Sainte-Claire Deville 1 published a description of the fumaroles found on Vesuvius during the eruption of 1855, which he classified in the order of dimin- ishing volcanic intensity. The classes proposed are as follows: 1. Dry fumaroles. Sublimates of metallic chlorides, with traces of sulphates. Sometimes fluorides are formed, as observed by Scacchi on the lava of 1850. These fumaroles are emitted directly from incandescent lava, and the subliming vapors are mixed with a gas which is essentially atmospheric air. A special group of dry fuma- roles emit ammonium chloride. 2. Acid fumaroles. Water vapor, mixed with hydrochloric and sulphurous acids. Commonly accompanied by chlorides of iron and copper, which are deposited around the vents. The vents occur on lava, either in the main crater or along the fissure of eruption. The hydrochloric acid is very largely in excess of the sulphurous. 3. Fumaroles emitting water vapor containing hydrogen sulphide or free sulphur. Their temperature rarely exceeds 80° . 4. Mofettes. Emissions of water vapor with carbon dioxide. These appear where the volcanic intensity has become very slight. 5. Fumaroles emitting water vapor alone. Although, as we shall see later, this classification is incomplete, it serves a useful purpose in giving a rough outline of the phenomena. At the point of greatest activity dry vapors appear; farther away, or as cooling progresses, acids are formed, and emanations of carbon dioxide mark the dying out of the volcanic energy. But there are fumaroles, like some of those in Iceland, which do not fall in any one of these classes. In 1858 C. Sainte-Claire Deville and F. Leblanc 2 published their analyses of volcanic gases, not only from Vesuvius, but also from Vulcano, Etna, and other localities. A fumarole in the crater of Vesuvius, emitting a gas of extremely suffocating odor, yielded hydro- chloric acid and sulphur dioxide in the ratio of 86.2 : 13.8. The bulk of the gas, after removal of these substances and water, was essentially atmospheric air slightly impoverished in oxygen. Other Vesuvian fumaroles also emitted similar air, with small but vari- able admixtures of sulphur dioxide, hydrogen sulphide, and carbon dioxide. Sulphur dioxide and carbon dioxide, however, were mutu- ally exclusive and never occuned together. The emanations from Etna resembled those from Vesuvius. 1 Bull. Soc. geol. France, 2d ser., vol. 13, 1855-56, p. 606; vol. 14, 1856-57, p. 254. 2 Annales chim. phys., 3d ser., vol. 52, 1858, p. 5. VOLCANIC GASES AND SUBLIMATES. 263 At Vulcano Deville and Leblanc made a number of striking obser- vations, which are well illustrated by the following selected analyses : Analyses of gases from Vulcano. A. Gas from the crater issuing at a temperature above the melting point of lead. This fumarole deposits boric acid. The gas was collected from a vent which emitted flames. B. A gas similar to the foregoing, but not accompanied by boric acid. C. Sulphurous fumarole from the north flank of Vulcano. D. Gas from a cavity, filled with hot water, known as “ Acqua-Bollente,” and situated near the seashore. E. Gas from depressions still farther from the crater, collected over water having a temperature of 25° C. A B c D E co 2 None. None. None. 6.4 86.0 so 2 39. 13 27. 50 69. 6 h 2 s.. 83. 1 o 2 10. 10 14. 02 5.5 . 7 None. N 2 50. 77 58. 48 24. 9 9.8 14.0 100. 00 100. 00 100.0 100.0 100.0 These analyses show very well the progressive change in the fuma- roles as they recede from the eruptive center. At the end of their memoir Deville and Leblanc give analyses of gases emitted from various springs in Sicily which have some relations to the volcanic activity of Etna. Some of them give off mainly carbon dioxide; others yield methane, CH 4 , in considerable quantities. A few analyses will illustrate the character of these exhalations. Analyses of gases from Sicilian springs. A. From the Lake of Palici. B. From the Salinelle of Paterno. C. From the Macaluba de Xirbi. D. From the Macaluba de Girgenti. A B c D C0 2 94. 70 90. 7 0. 70 1. 15 0 2 1. 10 1. 0 5. 17 1. 70 No 3. 52 3. 3 20. 40 6. 75 ch 4 .68 5.0 73. 73 90. 40 100. 00 100.0 100. 00 100. 00 The conclusion finally stated by Deville and Leblanc is as follows: The nature of the emanations from a given point varies with the time which has elapsed since the beginning of the eruption ; the fumaroles at different points vary with their distance from the volcanic center. In both cases the order of variation is the same. 264 THE DATA OF GEOCHEMISTRY. In 1865 F. Fouque 1 studied the Italian field with special reference to the exhaled gases. In the crater of Vulcano he examined three fumaroles, at different temperatures, with results as follows: Analyses of gases from fumaroles, Vulcano. A. Temperature above 350°. B. Temperature 250°. C. Temperature 150®. A B c HC1+S0 2 73. 80 66.00 27. 19 co 2 23. 40 22. 00 59. 62 Oo . 52 2. 40 2. 20 No 2.28 9. 60 10. 99 100. 00 100. 00 100. 00 In these gases the hydrochloric acid was most abundant, the sul- phur dioxide being almost negligible. Around the vents realgar, ferric chloride, and ammonium chloride were deposited. Another group of fumaroles, at a temperature of 100°, gave deposits of sul- phur, sometimes with and sometimes without boric acid. Their composition is given below, under D and E. Analyses of gases from fumaroles, Vulcano. D E F HC1 7. 3 None. h 2 s „ 10. 7 Trace. 17. 55 co 2 68. 8 63. 59 77. 02 Oo 2. 7 7. 28 . 70 No 11. 2 29. 13 4. 73 a 100. 7 100. 00 100. 00 a This summation suggests a misprint somewhere in the original column of figures. Analysis F represents gas from the fumarole known as “Acqua- Bollente,” which was examined by Deville and Leblanc nine years earlier. The loss of hydrogen sulphide and the gain of carbon dioxide during that period are most striking and show a decrease of volcanic activity. 2 The temperature of the fumarole is given as 86° C. Fouque’s analyses of gases from two small solfataras at Pozzuoli, near Vesuvius, also indicate a relationship between compo- sition and temperature. 1 Compt. Rend., vol. 61, 1865, pp. 210, 421, 564, 754. 2 See note by Deville, Compt. Rend., vol. 61, 1865, p. 567. For recent analyses of gases from Italian vol- canic sources, see R. Nasini, F. Anderlini, and R. Salvadori, Gazz. chim. ital., vol. 36, fasc. 1, 1906, p. 429. VOLCANIC GASES AND SUBLIMATES. 265 Analyses of gases from Pozzuoli. G (tempera- ture 96°). H (tempera- ture 77.5°). h 2 s 11. 43 None. CO, 56. 67 15. 09 0 2 5. 72 15. 51 No 26. 18 69. 40 100. 00 100. 00 An elaborate examination of the gases emitted by Etna during sev- eral eruptions led O. Silvestri * 1 to conclusions much like those reached by Deville and Leblanc, and he describes fumaroles of several classes, representing a progressive diminution of volcanic intensity. The data may be briefly summarized as follows: 1. The fresh, still flowing lava acts like one great fumarole, and emits from its sur- face white fumes. These are partly condensible, yielding a solid saline residue and a small amount of liquid containing free hydrochloric and sulphurous acids. The incondensible gas, as in the cases previously noted, is essentially atmospheric air slightly deficient in oxygen. One sample, upon analysis, gave 0 2 , 18.79 per cent; N 2 , 81.21 per cent. The white residue contained chiefly sodium chloride and car- bonate, and three deposits collected from the surface of the lava had the composition shown in the subjoined table. As the lava cools, the exhalations become localized and change their character with decreasing temperature. Analyses of deposits from surface of lava. NaCl 50. 19 63. 02 76. 01 KC1 . 50 . 27 . 03 Na 2 C0 3 11. 12 6. 49 2. 11 Na 2 S0 4 1. 13 Trace. . 75 HoO 30. 76 30. 22 21. 10 100. 00 100. 00 100. 00 In some cases the fumes also contain copper chloride, which forms, on the lava, deposits of atacamite and tenorite, the latter, obviously, by oxidation. 2. Ammonium-chloride fumaroles, which are divided into two subclasses. First, acid fumaroles, which form mostly upon the terminal walls of the lava stream and emit much hydrochloric acid. They also contain ferric chloride, which is partly con- densed as such and partly oxidized to hematite. As the temperature falls they develop hydrogen sulphide and deposit crystals of sulphur. Second, alkaline fuma- roles, which are free from hydrochloric acid and ferric chloride and deposit only ammonium chloride. They represent a lower temperature than the acid type. The gaseous portion of these exhalations, acid or alkaline, is still essentially air, contain- ing from 81.19 to 84.17 per cent of nitrogen. 1 1 fenomeni vulcanici presentati dell’ Etna, etc. , Catania, 1867. The data here given are from an abstract by G. vom Rath, Neues Jahrb., 1870, pp. 51, 257. See also the great monograph, “Der Aetna,” by Sarto- rius von Waltershausen and A. von Lasaulx, 2 vols., Leipzig, 1880. On the exhalations of Etna see also I. G. Ponte, Atti R. accad. Lincei, vol. 23, pt. 2, 1914, p. 341. 266 THE DATA OF GEOCHEMISTRY. 3. Water fumaroles, which give off only water vapor, mixed with impoverished air. Temperature relatively low. 4. Fumaroles emitting water vapor and carbon dioxide, the last phase of activity. The gases from two of three fumaroles in the crater of Etna, analyzed by Silvestri, had the following composition: Analyses of fumarole gases from Mount Etna. n 2 77. 28 79. 07 o 2 17. 27 18. 97 co 2 5. 00 1. 61 h 2 s .45 .35 100. 00 100. 00 Although the observations made by T. Wolf 1 at Cotopaxi were only qualitative, they confirm the belief that a regular order exists in the composition of volcanic exhalations. Near the crater the fumes of hydrochloric acid were overwhelming and there was a suspicion of free chlorine. At lower levels on the mountain hydrogen sulphide was recognized, and occasionally sulphur dioxide. The order, so far as it was studied, is the same as that noted in the volcanoes of the Mediterranean. In his great monograph on the volcanic eruptions of Santorin, 2 F. Fouque discusses at some length the gaseous emanations, in which, as in the Icelandic craters, free hydrogen appeared, and also small quantities of hydrocarbons. The great eruption of Nea Kameni, one of the islands of the archipelago, began in January, 1866, and some of the gases analyzed were collected in March. For the first time hydrogen and marsh gas were taken from an active volcano in the presence of true volcanic flames, and it was shown beyond reasonable doubt that in the central fires water had been dissociated into its elements. Ordinarily the combustible gases are burned as soon as they reach the air, hut the peculiar conditions prevailing at Santorin permitted their accumulation unchanged and rendered their complete identification possible. The subjoined analyses represent mixtures containing gases of this class: 1 Neues Jahrb., 1878, p. 163. 2 Santorin el ses eruptions, Paris, 1879. VOLCANIC GASES AND SUBLIMATES. 267 Analyses of volcanic gases from Santorin. A. Gas collected on Nea Kameni, March 17, 1866, from the surface of sulphurous water in a fissure be- tween Giorgios and Aphroessa, temperature 78°. Three other similar analyses are tabulated with this. B. From the same fissure on Nea Kameni, temperature 69°. Collected March 25, 1866. C. Gas collected March 7, 1867, over sea water, near the end of a still incandescent lava stream. D. Occurrence similar to C, but from a different stream. • Taken March 5, 1867. A B C D h 2 s Trace. Trace. co 2 36.42 50. 41 0. 22 None. Ho 29.43 16. 12 56. 70 1. 94 ch 4 .86 2. 95 .07 1.00 o 2 .32 .20 21. 11 a 24. 94 No 32. 97 30. 32 21.90 72. 12 100. 00 100. 00 100. 00 100. 00 a 25.94 in table, but corrected in list of errata at the end of the volume. Gas C was a true explosive mixture, which detonated violently upon contact with a flame. In collecting it special care was taken to avoid an admixture of air: its oxygen, therefore, is not from extraneous sources. It is possible, however, that both the oxygen and the hydro- gen in this instance came from the decomposition of sea water in contact with hot lava, although Fouque believed that they were pres- ent in the molten stream. In 1866 the largest proportions of hydrogen were found in gases taken from the principal fissures of the eruption, and they diminished in quantity with the distance of their points of issue from the focus of activity. A precisely similar diminution follows the lapse of time, as shown by analyses A and B of gases from the same locality, but collected eight days apart. Gases collected in May, 1866 , and some taken at greater distances from the center of eruption consisted either of carbon dioxide or of atmospheric air which had been entangled in the lavas. Some were heavily loaded with water vapor, which, when condensed and oxi- dized by nitric acid, gave a solution containing hydrochloric and sulphuric acids, the former, as in the instances previously cited, being largely in excess of the latter. Several of the dried gases had the composition shown in the subjoined table. 268 THE DATA OF GEOCHEMISTRY, Analyses of volcanic gases from Santorin. A. Gas taken May 4, 1866, from the bottom of a fissure on Nea Kameni. Collected over sulphurous water, at temperature 56°. B. Collected May 12, 1866, at the foot of the cone Giorgios, from a small fumarole surrounded by crystals of sulphur. Temperature 87°. C. Like B and near it, the sulphur partly crystallized and partly fused. Temperature 122°. D. Gas from periphery of eruptive field, March, 1867. E. Gas collected near the port of St. George of Nea Kameni, March 9, 1867. A B C D E h 2 s Trace. 0. 42 0. 90 co 2 95. 37 5. 88 12. 24 None. 56. 63 0 2 .49 18. 99 16. 41 20. 62 1. 84 n 2 4. 14 74. 71 70. 45 79. 38 41. 41 ch 4 . 12 100. 00 100. 00 100. 00 100. 00 100. 00 These analyses all tell the same story as that given by the Italian investigations; carbon dioxide appears as the volcanic intensity dies away; only at Santorin the maximum of activity is represented by hydrogen, and the acid products were less completely examined. For other volcanic regions the data relative to gaseous exhalations are not so complete. Three analyses by H. Moissan 1 of gases from West Indian fumaroles are, however, especially interesting on account of the determinations of argon . 2 The analyses are as follows: Analyses of gases from West Indian fumaroles. A. From a fumarole on Mont Pelee, Martinique. Gas collected by Lacroix after the great eruption of May, 1902. Temperature about 400°. Gas at first saturated with steam. Around this vent ammonium chloride and sulphur were deposited. B. From the Fumarole du Nord, Guadeloupe. C. From the Fumarole Napoleon, Guadeloupe. Gases A and B, previous to analysis, were both saturated with water. • A B c co 2 15.38 52.8 69.5 CO •. 1.60 None. None. CH, 5.46 None. None. Ho 8.12 None. None. Oo 13.67 7.5 2.7 No 54.94 36.07 22.32 A .71 .73 .68 HC1 | Trace. Trace. None. H 2 S 2.7 4.5 S, vapor Trace. Trace. Trace. 99.88 99.80 99.70 1 Compt. Rend., vol. 135, 1902, p. 1085; vol. 138, 1904, p. 936. For details relative to these fumaroles and other volcanic emanations, see the monograph by A. Lacroix, La Montagne Pel6e et ses Eruptions, Paris, 1904. F. Fouqu6, Compt. Rend., vol. 66, 1868, p. 915, analyzed gases from a submarine eruption near the Azores. H. Gorceix (idem, vol. 75, 1872, pp. 154, 270; vol. 78, 1874, p. 1309) examined gases from Vesuvius, Santorin, and Nisyros; gases from St. Paul Island were studied by C. Velain, idem, vol. 81, 1872, p. 332. A paper by W. Hempel on volcanic gases is in Zeitschr. Vulkanologie, vol. 1, 1914, p. 153. 2 Argon and helium have been detected in the gases from the boric fumaroles of Tuscany by C. Porlezza and G. Norzi, Atti R. accad. Lincei, vol. 20, 1911, p. 338. VOLCANIC GASES AND SUBLIMATES. 269 Here the recent gas is noticeably charged with combustible sub- stances, the lower activity of Guadeloupe being shown by their absence and by the larger quantities of carbon dioxide. Carbon mon- oxide appears in the Mont Pelee emanation, which emphasizes the observations made by W. Libbey 1 on Kilauea. He, by spectroscopic study of the volcanic flames, found that hydrogen, carbon monoxide, and hydrocarbons were probably present. Hydrogen had been simi- larly observed by J. Janssen 2 much earlier — namely, in volcanic flames at Santorin in 1867, and at Kilauea in 1883. The spectral lines of sodium, copper, chlorine, and carbon compounds were also seen. Much more fundamental work on Kilauea was done by A. L. Day and E. S. Shepherd, 3 who spent several months on the volcano during 1912. They not only determined the temperature of the molten lava hi situ, but also collected the volcanic gases directly from an active cone. An iron tube was passed through the thin wall of the cone into the liquid lava, and connected externally with a train of glass tubes through which the gases were drawn by pumping. In the tubes at the beginning of the train 300 cubic centimeters of water were condensed in about 15 minutes; this water and the attendant gases were after- ward analyzed. The water contained various saline substances, partly perhaps derived from the glass, but notable quantities of fluorine, chlorine, and sulphur dioxide were also determined. The dried gases from five of the tubes had the following composition by volume : Analyses of gases from Kilauea. co 2 23.8 58.0 62.3 59.2 73.9 CO 5.6 3.9 3.5 4.6 4.0 Ho 7.2 6. 7 7.5 7.0 10.2 No 63.3 29.8 13.8 29.2 11.8 so 2 None. 1.5 12.8 None. None. 99.9 99.9 99.9 100.0 99.9 No chlorine was found in these gases and no argon, the latter fact proving that there was no admixture of atmospheric air. The gases were truly magmatic. The significance of these observations will appear later in relation to the researches of Brun. The abundance of water in the molten lava was definitely established. SUBLIMATES. It has already been remarked that the gases issuing from a volcano are often if not always accompanied by substances which are gaseous only at high temperatures and are deposited, upon cooling, in solid 1 Am. Jour. Sci., 3d ser., vol. 47, 1894, p. 372. 2 Compt. Rend., vol. 64, 1867, p. 1303; vol. 97, 1883, p. 601. * Bull. Geol. Soc. America, vol. 24, 1913, p. 573. 270 THE DATA OF GEOCHEMISTRY. form. These sublimates, as they are called, are of many different kinds, and it is sometimes difficult to determine whether a given example is a true sublimation or is produced by secondary changes. To discriminate between the products of direct condensation from vapor and substances due to the action of the gases upon lava is not always easy. Some of the so-called sublimates are nonexistent at high temperatures, and are formed only upon cooling; 1 others result from decompositions of volatile matter; and still others are generated by reactions between different gases. For example, sulphur may be directly sublimed; it may be formed by the decomposition of hydro- gen sulphide or by the partial oxidation of that compound; and it is precipitated from mixtures of hydrogen sulphide and sulphur dioxide, two compounds which can not exist together. When they are com- mingled, sulphur is set free. By either of these processes volcanic sulphur can be deposited; but only the first is strictly a sublimation; that is, the volatilization and recondensation of a substance without chemical change. It is perhaps permissible, however, to use the term sublimate a little more loosely, for rigidly accurate discrimination is not practicable in the present instance. Any solid, then, depos- ited by or from volcanic gases, may be regarded conventionally as a sublimate. 2 The most conspicuous of all the volcanic sublimation products is undoubtedly native sulphur. It is found in or near all active volcanic craters, and it often contains appreciable quantities of selenium, as in the well-known selensulphur of the Lipari Islands. Tellurium has been found in Japanese sulphur, 3 to the extent of 0.17 per cent; and A. Cossa 4 reports it as present in some of the soluble salts which are formed stalactitically in the crater of Vulcano. The last-named locality has been studied with more than ordinary thoroughness, and among its fumarole deposits, which are partly sublimates and partly secondary products, A. Bergeat 5 names realgar, boric acid, sodium chloride, ammonium chloride, 6 ferric chloride, glauberite, lithium sulphate, sodium sulphate, alum, 7 hieratite, 8 and compounds of cobalt, zinc, tin, bismuth, lead, copper, and phosphorus. The chlorides named in this list are commonly found in volcanic craters, and the chlorides of potassium, calcium, magnesium, ferrous iron, manganese, lead, and aluminum have also been observed. 1 For example, ammonium chloride, which when vaporized is dissociated into NH3+HCI. 2 On the conditions under whichx different modifications of sulphur are deposited around volcanoes see A. Brim, Chem. Zeitung, No. 15, 1909. Bran holds that the H 2 S, SO 2 reaction does not take place in solfataras. 3 E. Divers and T. Shimidzu, Chem. News, vol. 48, 1883, p. 284. 4 Zeitschr. anorg. Chemie, vol. 17, 1898, p. 205. 6 Die Aeolischen Inseln: Abhandl. Math.-phys. Classe, K. bayer. Akad., vol. 20, Abth. 1, 1899, p. 193. 6 Containing, according to Deville and Leblanc (Annales chim. phys., 3d ser., vol. 52, 1858, p. 5), also iodide. 7 Potash alum, containing caesium, rubidium, and thallium. A. Cossa, Atti R. accad. Lincei, 1878, pt. 2, p. 34. 8 Potassium silicofluoride, K 2 SiF 6 . A. Cossa, Compt. Rend., vol. 94, 1882, p. 457. VOLCANIC GASES AND SUBLIMATES. 271 At Vesuvius A. Lacroix 1 found large crystals of potassium chloride and other crystals consisting of a double chloride of potassium and manganese. Mixed chlorides of sodium and potassium are reported by E. Casoria 2 and G. Freda. 3 These salts, however, are interpreted by F. Henrich 4 as secondary, formed by the action of moisture and hydrochloric acid on the alkaline silicates of the heated lavas. From ferric chloride the rare minerals kremersite, KNH 4 FeCl 5 .H 2 0, and erythrosiderite, K 2 FeCl 5 , are derived, and also hematite; while copper chloride yields the oxide, tenorite; chlorothionite, K 2 S0 4 .CuC 1 2 ; dole- rophanite, Cu 2 S0 5 ; and cyanochroite, K 2 Cu(S0 4 ) 2 .6H 2 0; with some hydrous chlorides and oxychlorides. Even manganese is found in the mineral chlormanganokalite, K 4 MnCl 6 , discovered by H. J. Johnston-Lavis. 5 The simple anhydrous chlorides are the true sub- limates; the other compounds are generated from them by secondary reactions. From the fluorine gases we get hieratite, ammonium silicofluoride, rarely fluorspar, and the oxyfluoride of calcium and magnesium, nocerite. Most of these substances were first described from Vesuvius, and we owe our knowledge of them to the indefatigable labors of A. Scacchi, who has also described many sulphates, simple, double, or basic, which are formed by the action of solfataric vapors upon the surrounding rocks. Similar sulphates, of sodium, potassium, calcium, magnesium, and aluminum, were found by A. Lacroix 6 among the fumarole products of Mont Peiee. Sodium carbonate is also produced in a secondary way. Silver was discovered by J. W. Mallet 7 in volcanic ash from Cotopaxi and Tunguragua ; and it is quite probable that this metal, which volatilizes readily, was ejected as vapor. Silver begins to vaporize not much above its melting point, and at the temperature of the oxyhydrogen flame it can be distilled easily. Sulphides have been found as sublimation products at Vesuvius, formed perhaps by the action of hydrogen sulphide upon volatilized metallic chlorides. A. Lacroix 8 and F. Zambonini 9 both report galena among the substances produced during the eruption of April, 1906, and Lacroix mentions pyrite and pyrrho tite also. 1 Compt. Rend., vol. 142, 1906, p. 1249. See also H. J. Johnston-Lavis, Nature, May 31, 1906. In Bull. Soc. min., vol. 30, 1907, p. 219, Lacroix has described the minerals of the Vesuvian fumaroles in consid- erable detail. 2 Abstract in Zeitschr. Kryst. Min., vol. 41, 1906, p. 276. Casoria found molybdenum, bismuth, copper, and zinc in Vesuvian salts. 3 Gazz. chim. ital., vol. 19, 1888, p. 16. 4 Zeitschr. angew. Chemie, vol. 19, 1906, p. 326; vol. 20, 1907, p. 179. 5 Mineralog. Mag., vol. 15, 1908, p. 54. s Bull. Soc. min., vol. 28, 1905, p. 60. Lacroix (Compt. Rend., vol. 144, 1907, p. 1397) has recently dis- covered a double sulphate of potassium and lead among the fumarole products of Vesuvius. This new mineral is named palmierite. 7 Proc. Roy. Soc., vol. 42, 1887, p. 1; vol. 47, 1889-90, p. 277. 8 Compt. Rend., vol. 143, 1906, p. 727. 9 Idem, p. 921. In Zambonini’s great monograph, Mineralogia Vesuviana, published by the Naples Academy in 1910, full details are given of each species found at Vesuvius, together with thorough biblio- graphic references. 272 THE DATA OF GEOCHEMISTRY. The ammonium salts found in volcanic emanations were partially- considered in the preceding pages. They are very common, hut their significance has been variously interpreted. Some writers have argued that their nitrogen is derived from organic matter, such as vegetation, with which the flowing lava has come into contact — an opinion which is not well sustained. O. Silvestri, 1 in 1875, found silvery incrustations of an iron nitride, Fe 5 N 3 , on an Etna lava, and conducted a series of experiments to determine its origin. Fragments of lava were first heated in gaseous hydrochloric acid, when water was expelled, silica was liberated, and chlorides of iron were formed. Subsequent heating of the mass in a stream of ammonia formed hydrochloric acid again, together with ammonium chloride, hydrogen, and a nitride of iron. Ammonium chloride, acting on lava at a red heat, gave similar products. Ammonia alone, passed over heated lava, was decomposed, yielding a gas containing 90 per cent of hydro- gen, while a large part of its nitrogen was absorbed. On the other hand, it is well known that when metallic nitrides are heated in steam, ammonia is formed. We have, therefore, something like a group of reversible reactions to deal with, not strictly reversible perhaps, but of such a character as to render it uncertain which com- pound, nitride or ammonia, existed first. Either substance can be generated from the other. J. Stoklasa, 2 however, regards it as pos- sible that nitrides, formed deep within the earth, are the initial com- pounds. At all events, he has clearly shown that the nitrogen of lava is an original constituent, and not of organic origin. In all of the lavas ejected by Vesuvius during the eruption of 1906 ammonium compounds were found, the largest amount, 300 milligrams of NH 3 per kilogram, being extracted from an olivine bomb. The water- soluble portion of the lapilii contained 33 per cent of ammonium chloride. Organic contamination, in the samples of lava examined, was impossible. An alternative hypothesis, framed to account for the volcanic ammonia, is that of O. Kosenbach, 3 who argues that it may be generated by reactions between atmospheric nitrogen and hot lava, in presence of moisture and hydrochloric acid. This sug- gestion is supported by very little evidence and needs experimental verification. It is difficult to assign any limit to the possibilities of sublima- tion within the vent of an active volcano. Given a temperature sufficiently high, and almost any mineral matter may be volatilized or decomposed into volatile constituents. In the electric furnace, 1 Gazz. chim. ital., vol. 5, 1875, p. 301; Pogg. Annalen, vol. 157, 1876, p. 165. Silvestri’s results have been questioned and need confirmation. 2 Ber. Deutsch. chem. Gesell., vol. 39, 1906, p. 3530; Chem. Zeitung, vol. 30, 1906, p. 740; Centralbl. Min., Geol. u. Pal., 1907, p. 161. See also R. V. Matteucci, Centralbl. Min., Geol. u. Pal., 1901, p. 45, on am- monium chloride in the crater of Vesuvius. 3 Natur. Wochenschr., vol. 21, 1906, p. 740. VOLCANIC GASES AND SUBLIMATES. 273 H. Moissan 1 has vaporized alumina, lime, magnesia, silica, zirconia, and titanic oxide, and these substances are all found in volcanic rocks. The oxides of the iron group are more stable, and fuse but do not seem to distill. According to these observations, alumina volatilizes most easily, lime quite easily, and magnesia with less facility. P. Schutzen- berger 2 has observed that silica gradually loses weight in a good wind furnace, whose temperature is far below that of the electric arc; and E. Cramer 3 has completely vaporized rock crystal under similar con- ditions. Cramer used a Deville furnace, with gas carbon or retort graphite for fuel, with a blast of air; and in one experiment 4.517 grams of quartz were evaporated. At the temperature of melting cast iron, quartz was stable and lost no weight; although Moissan 4 has observed that at 1,200° silica appears to have an appreciable tension. According to A. L. Day and E. S. Shepherd, 5 quartz vapor- izes rapidly in air at about the temperature of melting platinum. Silica, then, is volatile at temperatures which are probably reached or exceeded within the volcanic reservoirs ; and it may appear among the products of sublimation. In fact, quartz, tridymite, and various silicates have been repeatedly observed in lavas under conditions which indicated an origin of this kind. A. Scacchi, 6 for example, reports leucite, augite, hornblende, mica, sodalite, microsommite, cavolinite, garnet, and possibly sanidine and vesuvianite as formed by sublimation at Vesuvius. Furthermore, experiments recently conducted by A. L. Day and E. T. Allen in the laboratory of the United States Geological Survey have shown that feldspars can be easily sublimed at the temperature of the electric arc, a temperature which is in the neighborhood of 3,700° C. 7 The actual temperature at which the volatility of silicates begins is yet to be ascertained; but it is certainly lower than that employed in Day and Allen’s experiments. It may fall within the range of volcanic tempera- tures; and in that case sublimation can be supposed to play an appre- ciable part among the phenomena of eruptions. 8 If the more vola- tile substances accumulate in the upper portions of a reservoir, they 1 Le four electrique, pp. 32-49, Paris, 1897. See also Compt. Rend., vol. 116, 1893, p. 1222. 2 Compt. Rend., vol. 116, 1893, p. 1230. s Zeitschr. angew. Chemie, 1892, p. 484. * Compt. Rend., vol. 138, 1904, p. 243. s Science, new ser., vol. 23, 1906, p. 670. 6 Zeitschr. Deutsch. geol. Gesell., vol. 24, 1872, p. 493. Condensed from the Italian original by J. Roth. See also G. vom Rath, Neues Jahrb., 1866, p. 824, on augite as a fumarole product. H. Traube (Centralbl. Min., Geol. u. Pal., 1901, p. 679) has described the artificial production of minerals by sublimation. 7 3,900° to 4,000° absolute. See C. W. Waidner and G. K. Burgess, Bull. Bureau of Standards, vol. 1, 1904, p. 109. 8 J. Joly (Proc. Roy. Irish Acad., 3d ser., vol. 2, 1891, p. 38) mentions the sublimation of enstatite at the highest temperatures observed on the platinum ribbon of his meldometer. In this case the temperature could not have exceeded 1,700°. Some of the so-called sublimed silicates of volcanoes, however, may not be true sublimates at all, but products of reactions between silica and volatile chlorides or fluorides. Such reactions are more than probable. 97270°— Bull. 616—16 18 274 THE DATA OF GEOCHEMISTRY. would appear among the first ejectamenta; and the difference between the earlier and later outflows of an eruption would be partly accounted for. Whether this factor in the eruptive process is rela- tively small or large can not be determined at present. It probably exists, and it may be important ; but no more definite conclusion can be drawn from the established evidence. OCCLUDED GASES. Although we can not determine with absolute certainty the origin of volcanic gases, the subject is not entirely unsuited to scientific dis- cussion. Some evidence exists, and from it some conclusions may be legitimately drawn. It has long been known that nearly if not quite all rocks, upon heating to redness, give off large quantities of gas — a fact which was noted by Priestley as early as 1781. 1 In recent years these gases have been elaborately studied, and from two points of view. At first they were thought to be occluded in the rocks; and, indeed, inclosures of carbon dioxide are not rare; but latterly it has been shown that igneous action may generate them from the solid minerals themselves. Let us first assemble the data, and then con- sider their significance. That quartz and other crystalline minerals often contain cavities filled with carbon dioxide is well known, and inclusions of this order have been studied by several competent authorities. 2 Hawes and Wright examined the remarkable smoky quartz from Branchville, Connecticut, which contains so many inclusions of gas that it explodes almost like a percussion cap when struck with a hammer. In this case the gas, as analyzed by Wright, gave 98.33 per cent of C0 2 , with 1.67 per cent of nitrogen, and traces of hydrogen sulphide, sul- phur dioxide, ammonia, a fluorine compound, and possibly chlorine. Much water was also present with the gaseous inclusions. In other minerals other gases are sometimes found in notable quantities, as, for example, hydrogen sulphide in a Canadian calcite, 3 and marsh gas, which Bunsen 4 extracted from the rock salt of Wielieczka. In the latter instance the inclosed gases contained 84.60 per cent of methane, 10.35 per cent of nitrogen, and small quantities of oxygen and carbon dioxide. These minerals, however, are not volcanic, and they are cited here merely to show that gaseous inclusions are not unusual. The observations of W. Bamsay and M. W. Travers 5 are 1 See his letters to Josiah Wedgwood, in Scientific correspondence of Joseph Priestley, edited by H. Carrington Bolton, New York, 1892, privately published. 2 See especially W. N. Hartley, Jour. Chem. Soc., vol. 29, 1876, p. 137; vol. 30, 1876, p. 237. G. W. Hawes, Am. Jour. Sci., 3d ser., vol. 21, 1881, p. 203. A. W. Wright, idem, p. 209. 3 See B. J. Harrington, Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 345. 4 Annalcs chim. phys. , 3d ser., vol. 38, 1853, p. 269. 5 Proc. Roy. Soc., vol. 60, 1896-97, p. 442. Argon and helium have also been found in malacone, a variety of zircon, by E. S. Kitchin and W. G. Winterson (Jour. Chem. Soc., vol. 89, 1906, p. 1568). Many of the rare-earth minerals, according to H. Erdmann (Ber. Deutsch. chem. Gesell.,vol. 29, 1896, p. 1710), contain small quantities of nitrogen. VOLCANIC GASES AND SUBLIMATES. 275 also interesting, for in zircon they found both argon and helium, and the latter gas was yielded by a number of other rare-earth minerals and also uraninite, all obtained from pegmatite veins. In 1876, in the course of his investigations upon the gases evolved from meteorites, A. W. Wright 1 found that a specimen of trap, heated to redness, gave off three-fourths of its volume of gas, which con- tained 13 per cent of carbon dioxide, the remainder being chiefly hydrogen. In 1896, W. A. Tilden 2 made a similar observation upon the red Peterhead granite. This rock gave off 2.61 times its volume of gases, containing 24.8 per cent of C0 2 and 75.2 per cent of hydro- gen. A year later 3 Tilden published the results of his experiments upon a considerable number of rocks and minerals, 24 examples in all. For most of these only partial analyses were made, but in five cases the gases evolved were more completely examined. The data are as follows for the percentage composition of the gases and for the vol- ume obtained from a unit volume of rock: Volume and composition of gases evolved from rocks . Rock. Volume of gas. Composition of gas. C 0 2 CO ch 4 n 2 h 2 Granite 2.8 23. 60 6. 45 3. 02 5. 13 61. 68 Gabbro 6.4 5. 50 2. 16 2. 03 1. 90 88. 42 Pyroxene gneiss 7. 3 77. 72 8. 06 .56 1. 16 12. 49 Corundum gneiss 17.8 31. 62 5. 36 . 51 .56 61. 93 Basalt 8.0 32. 08 20. 08 10. 00 1. 61 36. 15 Even such a mineral as beryl gave off 6.7 volumes of gas, in which hydrogen largely predominated. The gases appeared to Tilden to be wholly inclosed in very minute cavities, so small that little was lost when the rocks were reduced to powder. Their extraction was effected by the usual process of heating the pulverized material in vacuo. In 1898 M. W. Travers 4 described a series of experiments upon the extraction of gases from various minerals and rocks, which led to results resembling those obtained by Tilden. The conclusions reached, however, were quite different; for Travers was able to show that in some cases at least the gases were not occluded but were derived from the interaction of nongaseous substances. Chlorite, serpentine, gabbro, mica, talc, feldspar, and glauconite were studied, and in each instance the hydrogen and carbon monoxide that were evolved by heating the mineral in vacuo were quantitatively related 1 Am. Jour. Sci., 3d ser., vol. 12, 1876, p. 171. 2 Proc. Roy. Soc., vol. 59, 1895-96, p. 223. 3 Chem. News, vol. 75, 1897, p. 169. Proc. Roy. Soc., vol. 60, 1896-97, p. 453. 4 Proc. Roy. Soc., vol. 64, 1898-99, p. 130. 276 THE DATA OF GEOCHEMISTRY. to the ferrous oxide and water which the specimen contained. The inference is that these gases were generated by a reaction between the ferrous salts, the carbon dioxide, and the water of the original sili- cates. Unfortunately, Travers’s conclusions can not be directly applied to Tilden’s work, for the latter gave no analyses of the rocks themselves. It is noticeable, however, that the largest evolution of gas cited in Tilden’s series was that from the corundum gneiss of Seringapatam, and not from the presumably more highly ferruginous pyroxene gneiss and basalt. The yield of gas from beryl was also very considerable, a fact which Travers’s observations do not explain. That molten glass absorbs combustible gases, probably hydrogen, was observed by H. Sainte-Claire Deville and L. Troost. 1 The glass on cooling gives out much of the gas in the form of bubbles. Even solid glass, at 200° and under a pressure of 200 atmospheres, has been found by J. B. Hannay 2 to absorb oxygen and carbon dioxide. When the charged glass is cooled under pressure the gases are retained, but on quick heating to the softening point they are expelled with almost explosive violence, driving the glass into foam. By slow heating to 300° most of the dissolved gas can be quietly discharged. The investigations of A. Gautier 3 led to the same conclusion as that reached by Travers, but the work was more extended and various methods of attack were employed. Two samples of the same granite, collected at different times and heated to 100° in vacuo with sirupy phosphoric acid, gave off the following gases, measured in cubic cen- timeters per kilogram of rock: Gases evolved by granite in vacuo at 100°. A B HC1 and SiF 4 Trace. Trace. H 2 S 1. 33 22. 7 CO,... 272. 6 237. 5 Hydrocarbons 12. 3 5. 3 H 2 53. 05 191. 48 N 2 (rich in argon) 232. 50 102, 48 571. 78 559. 46 On heating the same rock to 300° with water alone gases were evolved as follows, in cubic centimeters per kilogram: 1 Compt. Rend., vol. 57, 1863, p. 965. 2 Chem. News, vol. 44, 1881, p. 3. A. A. Campbell Swinton (Chem. News, vol. 95, 1907, p. 134) has also shown that gases are occluded by the glass walls of vacuum tubes. Barus’s work on the absorption of water by glass is considered in Chapter IX. 3 Compt. Rend., vol. 131, 1900, p. 647; vol. 132, 1901, pp. 58, 189; vol. 136, 1903, p. 16. Annales chim. phys., 7th ser., vol. 22, p. 97, 1901. VOLCANIC GASES AND SUBLIMATES. 277 Gases evolved by granite heated to 300° with water. A B h 2 s 1. 3 1 . 0 COo 7. 2 5. 3 h 9 46. 0 14. 6 No . 3 5.9 Hence, it is clear that the action of water alone on an igneous rock moderately heated tends to develop gases closely similar in character to those which are emitted by active volcanoes. Heated to redness in vacuo, powdered rocks emit much more gas and the volcanic phenomena are imitated even more closely. In the subjoined' table A, B, and C are analyses of gases thus extracted from the granite of Vire; D represents a granitoid porphyry, E an ophite, and F lher- zolite. The percentages by volume are given, and the volume of gas, reduced to 0° and 760 millimeters, yielded by 1 kilogram of rock. Analyses of gas evolved from powdered rocks heated to redness. A B C D E F C0 2 14. 80 8. 98 14. 42 59.25 35. 71 78.35 H 2 S Trace. . 1. 71 .69 None. .45 11. 85 CO 4. 93 5. 12 5. 50 4.20 4. 85 1. 99 CH 4 2. 24 1.09 1. 99 2. 53 1. 99 .01 h 2 77. 30 82. 80 76. 80 31.09 56.29 7. 34 N 2 (with argon) .83 .42 .40 2. 10 .68 Trace. Volume of gas, cubic centi- 100. 10 100. 12 99. 80 99. 17 99. 97 99. 54 meters 2, 709 4, 209 2, 570 2, 846 2, 517 5, 450 Before heating, these rocks were dried at 250° to 300° to remove hygroscopic moisture. The volume of gas extracted from one volume of rock amounted to 6.7 from the granite, 7.6 from the porphyry, 7.6 from the ophite, and 15.7 from the lherzolite. The granite, it will be seen, gives the smallest evolution of gas per volume of material, but it is by far the richest in hydrogen. Even in this case, according to Gautier, a cubic decimeter of granite at 1,000° would give, calculated for that temperature, about 20 liters of mixed gases and 89 liters of steam — more than one hundred times its initial volume. In order to prove that the gases are not simply inclosed in the rocks, Gautier extended his- experiments along several lines. First, he argued, inclosed gases should not vary in composition during the process of extraction, whereas gases generated by heat might do so. 278 THE DATA OF GEOCHEMISTRY. The latter condition held in the case of granite when two fractions of the gas were examined separately. The analyses are as follows: Analyses of gas evolved from granite. First third. Last two- thirds. co 2 20. 19 6. 13 H,S 1.28 .41 CO . 57 1. 02 ch 4 2. 04 . 80 h 2 75. 54 91. 64 No .30 . 30 99. 92 100. 30 A similar variation was exhibited during the evolution of gas from ophite. In his third memoir Gautier showed that ferrous silicates heated to redness in a current of steam yield a gas containing 65 per cent of hydrogen. Therefore the water of constitution in a rock, acting on the compounds of iron therein contained, can give the same reaction. To test this conclusion still further, Gautier heated 150 grams of dried and powdered ophite to redness in vacuo and obtained 2.25 grams of water and 371 cubic centimeters of gas, contain- ing 202 cubic centimeters of hydrogen and 122 cubic centimeters of carbon dioxide. After the evolution of gas had ceased, the mate- rial was allowed to cool, and then reheated in a current of steam carrying a little carbonic acid. By this means 70 cubic centimeters of gas were developed, having, after the removal of carbon dioxide, the subjoined composition: CO.... CH 4 . . . H 2 .... N 2 , etc 3.32 6. 08 36.20 54. 20 99. 80 This gas was certainly not preexistent in the rock, for that had been previously exhausted, and yet it was moderately rich in hydrogen. Gautier’s conclusions were, in the main, confirmed by K. Huttner. 1 He, too, found that the gases in question are generated by reactions brought about by heat within the rock; only, instead of regarding the CO as derived from the action of C0 2 on ferrous silicates, he showed that it can be produced by the reducing action of the liberated hydrogen upon C0 2 . Bocks containing more or less water were heated in a stream of carbon dioxide, when both hydrogen and car- bon monoxide were given off. Zeitschr. anorg. Chemie, vol. 43, 1905, p. 8. VOLCANIC GASES AND SUBLIMATES. 279 That such a reduction was possible had long been known; but Gautier, 1 in a later investigation, studied the reaction much more thoroughly and found that it was reversible. At a white heat the reaction is as follows: C0 2 + 3H 2 = CO + H 2 0 + 2H 2 . At temperatures between 1,200° and 1,250°, on the other hand, the equation becomes — 3CO + 2H 2 0 = 2C0 2 + 2H 2 + CO. In another series of experiments, Gautier 2 found that hydrogen at high temperatures, reduced carbon monoxide, forming carbon dioxide, water, and either free carbon or methane. 3 At 900° to 1,000° the reaction appeared to be — 4CO + 2H 2 = 2H 2 0 + C0 2 + 3C. Between 1,200° and 1,220° it was — 4CO + 8H 2 = 2H 2 0 + C0 2 4- 3CH 4 . From these reactions, which seem to be contradictory but which depend upon varying conditions of temperature and concentration, the coexistence of water vapor, hydrogen, and both oxides of car- bon in volcanic emanations becomes intelligible. When water emit- ted by heated rocks mingles with carbon dioxide from any source whatever, within the vent of a volcano, any of these reactions may take place, and mixed gases, which sometimes contain traces of formic acid, are generated. This mixture is a powerful reducing agent, which acts upon the iron silicates in an opposite direction to that of the oxidizing vapor of water. Either oxidation or reduction is therefore possible, according to the preponderance of one constitu- ent or another among the volcanic gases. Going further, Gautier 4 investigated the reactions between steam and the metallic sulphides. At incipient redness steam changes the iron sulphide, FeS, into magnetite, Fe 3 0 4 , with formation of free hydrogen and hydrogen s’ulphide. Galena, in a current of super- heated steam, was partly sublimed and recrystallized as such 5 6 and partly decomposed into metallic lead and free sulphur. A little sul- phate of lead was formed at the same time. With cuprous sulphide, under like conditions, copper was liberated and a mixture of hydro- gen with sulphur dioxide was formed. The same gaseous mixture was also generated by the action of steam upon hydrogen sulphide. 1 Compt. Rend., vol. 142, 1906, p. 1382; Bull. Soc. chim., 3d ser., vol. 35, 1906, p. 929. Gautier gives references to earlier literature. See also O. Boudouard, Bull. Soc. chim., 3d ser., vol. 25, 1901. 2 Compt. Rend., vol. 150, 1910, p. 1564. 3 Sir B. C. Brodie (Proc. Roy. Soc., vol. 21, 1873, p. 245) also obtained methane by the action of electric discharges upon a mixture of CO and H 2 . The reaction suggested is C0+3H 2 =CH 4 +H 2 0. * Compt. Rend., vol. 142, 1906, p. 1465; Bull. Soc. chim., 3d ser., vol. 35, 1906, p. 934. 6 This recalls the existence, already mentioned, of galena as one of the Vesuvian sublimates. 280 THE DATA OF GEOCHEMISTRY. From these facts Gautier infers that the sulphur dioxide of volcanoes is produced by the reduction of sulphides, followed by the oxidation of the hydrogen sulphide so liberated. This oxidation can be brought about, as Gautier 1 has shown, by reactions between metallic oxides and hydrogen sulphide, a reversion of some of the other reactions studied. At a red heat steam reduces ferrous sulphide, forming mag- netite. At a white heat hydrogen sulphide reconverts magnetite into FeS, and a mixture of sulphur dioxide with hydrogen is generated. Hydrogen sulphide may also react with carbon dioxide to form car- bonyl sulphide, COS, and water. In short, Gautier has shown that a large number of reactions are possible, starting only with water, car- bon dioxide, and the solid constituents of lavas. Many of these reac- tions are reversible, and they give rise to nearly all the gaseous mix- tures which appear hi volcanic emanations. The nitrogen of the vol- canic gases Gautier, like several other authorities, attributes to the presence of nitrides in the lava. In a more general memoir Gautier 2 has summed up his views upon the chemistry of volcanism. The phenomena, he thinks, are due to Assuring and subsidence in the crust of the earth, whereby masses of crystalline rocks are lowered into the heated region. Gases are then developed, in accordance with the reactions that he has established, under enormous pressures and in immense quantities. To illustrate the magnitude of the phenomena to which the reactions may give rise, Gautier in one of his earlier papers shows that a cubic kilometer of granite would yield 28,400,000 metric tons of water and 5,293,000,000 cubic meters of hydrogen, measured at ordinary temper- atures. That amount of hydrogen, burning, would give 4,266,000 tons of water, making nearly 31,000,000 tons in all, or as much as passes Paris in the Seine during an average flow of 12 hours. We can therefore account for the evolution of volcanic steam and gases by the action of heat alone without involving either the infiltra- tion of sea water or unknown and imaginary sources of supply deep within the bowels of the earth. Given a. mechanical source of heat and rocks of ordinary composition, and the observed chemical phenomena will follow. Gautier, however, goes further than the experimental data warrant. He supposes that the nucleus of the earth consists largely of iron, containing hydrogen and carbon monoxide in solution. He also assumes the existence of metallic carbides, from which CO and hydrocarbons may be generated. Sodium chloride, moreover, he regards as nuclear; and upon supposi- tions of this sort he builds up an elaborate argument, of which the soundness is yet to be established. It is rich in suggestions which i Compt. Rend., vol. 143, 1906, p. 7; Bull. Soc. chim., 3d ser., vol. 35, 1906, p. 939. 3 Annales des mines, 10th sor., vol. 9, 1906, p. 316. Compare F. Loewinson-Lessing (Compt. rend. VII Cong. g6ol. internat., 1897, p. 369), who attributes volcanic gases to the absorption of sedimentary rocks by magmas. Clays yield water, limestones furnish C0 2 , etc. VOLCANIC GASES AND SUBLIMATES. 281 may or may not bear fruit in future discoveries. The carbide theory, I may say, is not due to Gautier alone. It was also advanced by H. Moissan, 1 who attributes volcanic activity to the action of water upon metallic carbides, although these compounds are not seen as natural products on the surface of the earth. Water, acting upon the artificial carbides, develops hydrogen and hydrocarbon gases; the latter, through the influence of heat, partly polymerize to liquid or solid compounds and partly burn, yielding carbonic acid and water; and so the observed order of evolution seen in volcanic eruptions is paralleled. This view also finds some support in the observations of O. Silvestri 2 who obtained both solid paraffin and liquid hydro- carbons from the lavas of Etna. The theory accounts conveniently for some products of volcanism and may be true in part, for the carbides are readily formed and are likely to be present below the region to which the surface waters penetrate! If deep-seated waters really exist, then the carbide hypothesis must be abandoned, or else so qualified as to deprive it of any real significance. 3 Probably the most elaborate research upon the gases extractable from rocks is that of R. T. Chamberlin. 4 He gives more than a hundred analyses of gases obtained from rocks, minerals, and meteor- ites, finding H 2 S, CO, C0 2 , CH 4 , H 2 and N 2 . Chlorine and its com- pounds are not reported. The largest quantities of gas were with- drawn from ferromagnesian rocks, and in general, hydrogen and the carbon oxides predominated. In deep-seated rocks H 2 and C0 2 were about equally important; in surface flows the latter gas was more conspicuous. Among igneous rocks the oldest yielded the most gas, recent lavas gave very much less than the Archean plutonics. Chamberlin discusses his analyses with much thoroughness, espe- cially with reference to the origin of the gases. Like Gautier he ascribes the major portion of them to reactions within the rocks, brought about by heating. There must be, however, some gaseous occlusions, as in the case of beryl, which yielded him much more hydrogen than could possibly be generated by the small amounts of water and iron that the mineral contained. Inclusions, such as gas bubbles in quartz and the like, he regards as of minor importance. The water required to yield the hydrogen Chamberlin attributes in great part to the micas of the deep-seated rocks — that is, it was 1 Proc. Roy. Soc., vol. 60, 1896-97, p. 156. See also E. Stecher, 14. Ber. Naturw. Gesell. Chemnitz, 1900; A. Rossel, Arch. sci. phys. nat., 4th ser., vol. 14, 1902, p. 481; and H. Lenicque, Mem. Soc. ingen. civils France, October, 1903, p. 346. 2 Gazz. chim. ital., vol. 7, 1877, p. 1. 3 See the discussion over juvenile and vadose waters in Chapter VI, and also Gautier’s memoir, there cited, on the relations between volcanism and thermal springs. The occurrence of hydrocarbons has been noted at many volcanic centers. 4 Pub. No. 106, Carnegie Inst. Washington, 1908. Several analyses of gases from lavas of Mont Pelee and Vesuvius are given by M. Grossmann, Compt. Rend., vol. 148, 1909, p. 991. Another paper on gases from rocks is by R. J. Strutt, Proc. Roy. Soc., vol. 70A, 1907, p. 436. 282 THE DATA OF GEOCHEMISTRY. originally magmatic, and locked up in the minerals when the magma consolidated. In an interesting series of papers A. Brun 1 has advanced views in strong contrast with those of previous writers, for he regards water as of minor importance in the production of volcanic phenomena. He agrees, however, with Gautier in believing that the gases emitted by lava at the instant of its fusion are generated within it by chemical reactions. Their sources, he thinks, are nitrides of iron and silicon, hydrocarbons, and certain chloro-silicates, such as the compound Ca 2 Cl 2 Si0 3 , which he artificially prepared. 2 Hydrocarbons, in small amount, he extracted from lava, as Silvestri had done before him. From a Lipari lava, by heating to temperatures between 800° and 900°, Brun obtained abundant ammonium chloride. Quickly ignited at 900° it gave off free nitrogen. At volcanic temperatures the rock emitted chlorine and hydrochloric acid. The observed volcanic gases, according to Brun, are evolved by the action of the molten magma upon the compounds named above, and the temperatures of several stages in the process are as follows: 0° to 825°. Volatilization of water. 825°. First evolution of chloride vapors. 874° to 1,100°. Temperature of explosions. 1,100°. Mean temperature of flowing lava. 3 The vast clouds of vapor arising from volcanoes are thought by Brun to consist mainly of volatilized chlorides, with little or no steam. This conclusion is in direct opposition to the prevailing belief. In support of his views, Brun has personally studied Stromboli, Vesuvius, the volcanoes of Java and the Canary Islands, and Kilauea. In all cases he claims to have found the fresh volcanic glass or cinder to he practically anhydrous, and to yield a sublimate of ammonium chloride on heating to moderate temperatures. At higher tempera- tures, at or near the fusing point, gases were given off with explosive violence, and of a character quite unlike anything reported by pre- vious observers. For example, four obsidians from Krakatoa gave 498, 543, 380, and 435 cubic centimeters of gas per kilogram, of the following composition: 1 Arch. sc-i. phys. nat., 4th ser., vol. 19, 1905, pp. 439, 589; vol. 22, 1906, p. 425; vol. 25, 1908, p. 146; vol. 27, 1909, p. 113; vol. 28, 1909, p. 45; vol. 29, 1910, pp. 99, 618 (the last paper jointly with L. W. Collet); vol. 30, 1910, p. 576. A general summary of his conclusions is given by Brim in Rev. gen. sci., 1910, p. 51. His com- plete researches have been brought together in a superb quarto, Recherches sur l’exhalaison volcanique, Geneva, 1911. 2 Chlorosilicates known to exist in nature, like sodalite and several other species, are more probable sources of chlorine. Sodalite is among the minerals reported as sublimates at Vesuvius. 2 The temperature of the lava at Kilauea is given by Brun as 1,290°±40°. Arch. sci. phys. nat., 4th ser., vol. 30, 1910, p. 576. Day and Shepherd, by means of a thermocouple lowered into the center of the lava pool, determined its temperature as 1,000°. Carnegie Inst. Washington, Year Book No. 10, 1911, p. 91. VOLCANIC CASES AND SUBLIMATES. 283 Gases from Krakatoa. A B C D Cl 2 59. 64 11. 63 7. 99 6. 73 .50 4. 78 8. 73 49. 94 15. 54 11. 61 6. 87 Trace. 5. 68 10. 36 82. 04 None. 2. 46 8.89 None. 63.2 None. } 29.8 Trace. HC1 so 2 co 2 0 2 CO N 2 and other inert gases 6. 61 7.0 100. 00 100. 00 100. 00 100. 00 The chlorine contained a little sulphur chloride, and ammonium chloride was also collected and determined. Other obsidians from other volcanoes gave similar results, but with larger proportions of HC1 and S0 2 and much less free chlorine. In order to account for the extraordinary difference between these gases and those obtained by former investigators, Brun claims that he studied relatively fresh or “live” material, while his predecessors examined old or “dead” rocks, such as granites, etc. The distinction is of doubtful signifi- cance. 1 The surprising amounts of free chlorine found in Bran’s analyses are also questionable. The publication of Bran’s researches naturally led to controversy, especially between himself and Gautier. 2 Brun urges that the well- known volcanic sublimates of metallic chlorides, such as the chlorides of magnesium and iron, are incompatible with the presence of water in the magma, for they are easily hydrolyzed. To this Gautier replies that a large amount of hydrochloric acid in the volcanic emana- tions would inhibit, partially or altogether, the usual hydrolysis. Brun of course recognizes the obvious fact that superficial or meteoric waters play some part in eruptions, especially in the formation of fumaroles, but he regards that part as insignificant and is most emphatic in declaring that the magma itself, in the volcanic chimney, is anhydrous. The last point is the one on which he and Gautier principally differ. The fumarole gases, so far as they have been studied, seem to be generally hydrous, as is shown by a group of analyses by Gautier. 3 These gases were collected at Vesuvius, A and B three months after the eruption of 1906, C and D about fifteen months later. Gases A and B were emitted at a temperature near 300°, C and D at 250° to 280°. The undried gases had the subjoined composition. 1 Two of Chamberlin’s analyses relate to gases from fresh Vesuvian lava of the eruption of 1906. They contained principally CO 2 with much S0 2 , some CO and CH 4 , and minor amounts of H 2 and N 2 . These gases bear no resemblance to those reported by Brun. On the other hand, R. Beck (Monatsb. Deutsch. geol. Gesell., 1910, p. 240) found in gas extracted from obsidian 14.47 per cent Cl 2 and 50.75 HC1. 2 For Gautier’s share in the controversy see Arch. sci. phys. nat., 4th ser., vol. 24, 1907, p. 463, and Revue sci., 5th ser., vol. 8, 1907, p. 545, and Nov. 27, 1909. See also K. Sapper, Centralbl. Min., Geol. u. Pal., 1909, p. 609; A. C. Lane, Tufts Coll. Studies, vol. 3, 1908, p. 39; and J. Schwertschlager, Centralbl. Min., Geol. u. Pal., 1911, .p. 777. Bran’s papers have already been cited. 3 Bull. Soc. chim., 4th ser., vol. 5, 1909, p. 977. See also Compt. Rend., vol. 148, 1909, p. 1708; vol. 149, 1909, p. 84. 284 THE DATA OE GEOCHEMISTRY. Gases from Vesuvius. A B c D HC1 0. 78 Trace. None. None. co 2 11. 03 6. 68 0. 80 0. 66 CO None. None. . 15 .02 h 2 1.24 Trace. . 54 . 02 Oo 3. 72 6. 00 4. 59 3. 68 N 2 , A, etc 15. 49 24. 88 21.23 17. 86 H 2 0 vapor 67. 74 62.44 72. 69 77. 76 100. 00 100. 00 100. 00 100. 00 The water in these gases may of course have been of superficial origin. J. Prestwich 1 has noted that wells and springs near vol- canoes generally show a remarkable shrinkage just before eruptions, an observation which has some bearing upon the character of the more persistent volcanic emanations. The water that so vanishes may well reappear in the fumaroles which form later. A very serious objection to Brun’s opinions is the fact that deep-seated plutonic rocks, which presumably solidified out of reach of percolating waters from above, contain micas, of which water is one of the essential con- stituents. The analcite basalts and the highly hydrated pitchstones 2 are also difficult to understand if the magma is really anhydrous. Still more conclusive against Brun’s views are the observations of Day and Shepherd, already cited, who actually collected consider- able quantities of water directly from the molten lava of Kilauea. There, at least, the magma is not anhydrous. Brun’s arguments by which he seeks to prove its anhydrous nature are all discussed by Day and Shepherd, and effectively answered. On the whole, the work of Gautier on the chemistry of the volcanic gases seems to be the most general and satisfactory. Deductions from it, however, must not be pushed too far, for the evidence does not cover all the ground. That rocks contain some gaseous inclusions is established, although hydrogen may not be among them; and these were probably entangled when the magma first solidified. Percolating waters certainly reach volcanic matter from above, and it is highly probable that some water filters in from the sea. A volcano on the seaboard could hardly escape from receiving some accessions of that 1 Proc. Roy. Soc., vol. 41, 1886, p. 117. 2 In a recent publication (Zeitschr. f. Vulkanologie, vol. 1, p. 3, 1914), Bran attempts to show that the water of mica is not an essential part of the molecule. Upon that assumption the formula of muscovite becomes irrational. According to O. Stutzer (Monatsb. Deutsch. geol. Gesell., 1910, p. 102) the water of pitchstone is not magmatic. VOLCANIC GASES AND SUBLIMATES. 285 kind . 1 What the relative magnitude of these several factors may be we have no means of determining. Furthermore, experiments like those of Gautier do not reproduce the conditions existing within a volcano. His rocks were heated under conditions which removed the gaseous products as fast as they were formed; in a volcanic reservoir they must accumulate in contact with or permeating the lava until the pressure has been relieved by an explosion. Steam may oxidize a ferrous compound, but the hydrogen in its turn is a powerful re- ducing agent. There are here, then, two opposing tendencies, and we can not readily decide what sort of an equilibrium would be established between them. It is probable that in the depths of a volcano temperatures prevail which dissociate water into its elements, unless the enormous pressures there existing should compel some sort of union that would otherwise be impossible. The chemistry of great pressures and concurrently high temperatures is entirely unknown, and its problems are not likely to be unraveled by any experiments within the range of our resources. The temperatures we can com- mand, but the pressures are as yet beyond our reach. We may devise mathematical formulae to fit determinable conditions; but the mo- ment we seek to apply them to the phenomena displayed at great depths we are forced to employ the dangerous method of extrapola- tion, and our conclusions can not be verified. VOLCANIC EXPLOSIONS. It is generally admitted that the volcanic gases are the chief agents in producing volcanic explosions. This is emphasized by E. Reyer , 2 by A. C. Lane , 3 by S. Arrhenius , 4 and more recently by C. Doelter . 5 Lane and Doelter especially regard the deep-seated magmas as impregnated by gaseous mixtures which explode upon relief of pres- sure. As interpreted by Lane, these gases were absorbed by the early earth as original and necessary constituents of every magma, and their retention is essential to the development and crystallization of plutonic and dike rocks. Their sudden escape, due to the for- mation of cracks in the earth’s crust, is a prime cause of volcanic eruptions. Hypotheses of this order, varying only in detail, have been widely accepted, but they are not in complete harmony with the conclusions of either Gautier or Brun. It is plain that the consideration of the volcanic gases is directly connected with various current speculations concerning the origin of 1 G. A. Daubr6e, Etudes synthetiques de geologie experimental, 1873, pp. 235-241. 2 Beitrag zur Fysik der Eruptionen, Wien, 1877. 3 Bull. Geol. Soc. America, vol. 5, 1893, p. 259. 4 Geol. Foren. Forhandl., vol. 22, 1900, p. 411. 6 Sitzungsb. Akad. Wien, vol. 112, 1903, p. 681. 286 THE DATA OF GEOCHEMISTRY. the earth; and whether we incline to the nebular hypothesis or to the planetesimal conception, lately developed by T. C. Chamberlin, we must take them into account. Chamberlin and R. D. Salisbury 1 regard the gases as originally entangled in the meteoroidal matter, from which, according to the planetesimal hypothesis, the earth was formed, and they are therefore true additions to the atmosphere and hydrosphere. These authors admit that lavas in rising to the surface may encounter rocks saturated with moisture, and so generate some steam; but they argue that large accessions of water, such as infil- trations from the sea, would absorb more heat than the molten magma could afford to lose. Could Stromboli, for instance, which has been in continual activity for more than two thousand years, have retained its heat under such adverse conditions ? The question is pertinent, but not final, for we know nothing about the relative quantities of water and lava which are supposed to take part in the eruptions. A large molten reservoir and a moderate infiltration of water, a supply of heat greater than the wastage, are conceivable; and it is also to be remembered that some water lowers the melting point of a rock and so helps to preserve its fluidity. A considerable degree of cooling is not incompatible with aqueo-igneous fusion and would not necessarily check the outflow of a lava stream or the visi- ble activity of a volcano. Arrhenius 2 claims that a continuous activ- ity, like that of Stromboli, would be impossible without a steady sup- ply of water, and he regards the sea bottom as equivalent to a semi- permeable membrane through which, by osmotic pressure, the water is forced. This pressure at a depth of 10,000 meters would amount to 1,700 atmospheres. It is not as a liquid, however, but as a vapor, far above its critical temperature, that the water enters the magma, in which it is absorbed much as ordinary water is taken up by cal- cium chloride. During an eruption it is emitted as steam. The reverse movement of magma to the ocean is prevented, according to Arrhenius, by the impermeability of the intervening septum to the larger and heavier molecules of which the molten rock is composed, and especially to the amorphous silica which the entering water is supposed to set free. Here the nature of the fluid magma itself is in question — a subject which will be taken up more fully in the next chapter. So far, then, we have several distinct hypotheses to account for the gaseous exhalations of volcanoes. Arrhenius and Daubree, as 1 Geology, vol. 1, pp. 588-594, 602-618, 1904. See also ante, Chap. II, p. 56. According to Chamberlin and Salisbury, crystallization has much to do with the evolution of volcanic gases. When crystals form within a lava, they give up their gaseous load, which overcharges the still fluid portions of the magma, thereby causing increased pressure and provoking explosions. See analyses by R. T. Chamberlin, of gases from the rocks and phenocrysts of a small tuff cone, Red Mountain, Ariz., cited by W. W. Atwood, Jour. Geology, vol. 14, p. 138, 1906. 2 Geol. Foren. Forhandl., vol. 22, p. 411, 1900. VOLCANIC GASES AND SUBLIMATES. 287 well as many earlier writers, derive them from infiltrations of sea water, Arrhenius assuming osmotic pressure and Daubree capillary attraction as the method by which entrance to the magma was effected. Chamberlin and Lane regard the gases as original inclo- sures within the earth, now issuing from great depths. Gautier, Moissan, and Brun assign their origin to reactions within the rocks themselves, but differ as to the details of the process. Of all these differing views, that of Gautier involves the smallest amount of hypothesis, and it also has the merit of simplicity. It is not, however, as we have already seen, absolute and final, but it cer- tainly represents a part of the truth, and possibly the major portion. On the experimental side it needs further investigation, for it is dif- ficult to suppose that a fluid magma, saturated with gas and water, could emerge from a volcano and solidify without retaining some gaseous occlusions. In fact, the experiments of R. T. Chamberlin seem to prove that such occlusions exist, and the extent to which Gautier’s conclusions can be accepted depends upon their magnitude. Here we may properly resort to some evidence from analogy. Gaseous occlusions are taken up by iron, steel, and slags in ordinary furnace operations, and among them hydrogen is the most con- spicuous. 1 Data relative to the absorption of hydrogen by iron are abundant, 2 and meteoric iron seems always to contain it. 3 From the Lenarto iron T. Graham obtained 2.85 times its volume of gas, containing 86 per cent of hydrogen. From the Augusta iron Mallet extracted 3.17 volumes, in which hydrogen, carbonic oxide, carbon dioxide, and nitrogen were present. There is, to be sure, one adverse experiment by M. W. Travers, 4 on meteoric iron of unstated origin, which is not quite conclusive. By heating this iron, hydrogen was obtained; upon dissolving the iron in copper sulphate solution, none was evolved. The failure to develop hydrogen in the second experi- ment is held by Travers to prove its absence, at least as a gaseous occlusion. The possibility that hydrogen from a metallic hydride might be expended in the precipitation of copper seems not to have been investigated. The weight of evidence, so far, is that meteoric irons do occlude hydrogen, while meteoric stones yield a larger propor- tion of carbon dioxide. The Kold Bokkeveld carbonaceous meteorite 1 See table given by A. C. Lane in his paper, Geological activity of the earth’s originally absorbed gases: Bull. Geol. Soc. America, vol. 5, 1893, p. 264. See also references cited by G. Tschermak, Sitzungsb. Akad. Wien, vol. 75, 1877, pp. 170-174. 2 See, for example, L. Troost and P. Hautefeuille, Compt. Rend., vol. 76, 1873, p. 562; L. Cailletet, idem, vol. 61, 1865, p. 850; and Thoma, Zeitschr. physikal. Chemie, vol. 3, 1891, p. 91. Thoma’s paper gives many references to literature. H. Wedding and T. Fischer (Ber. V Internat. Kong, angew. Chemie, vol. 2, 1904, p. 25) have summed up the subject quite thoroughly. The papers by J. Parry (Am. Chemist, vol. 4, 1873-74, p. 225; vol. 6, 1875-76, p. 107) are also important. 3 T. Graham, Proc. Roy. Soc., vol. 15, 1866-67, p. 502. J. W. Mallet, idem, vol. 20, 1871-72, p. 365. A. W. Wright, Am. Jour. Sci.,3dser., vol. 9, 1875, p.294; vol. 10, 1875, p. 44; vol. 11, 1876, p.253; vol. 12, 1876, p. 166; 3. Dewar and G. Ansdell, Proc. Roy. Inst., vol. 11 1886, p.445. See also R.T, Chamberlin, lqc.cit. 4 Proc. Roy. Soc., vol. 64, p. 130, 1898-99. 288 THE DATA OF GEOCHEMISTRY. gave thirty times its volume of gas, in which carbon dioxide pre- dominated. The terrestrial native iron from Ovifak, in Greenland, gives off when heated, according to Woehler , 1 more than one hundred times its volume of gas, which is mainly carbon monoxide with a little dioxide. If Chamberlin’s theory of the earth’s origin is correct, we have in these gases an adequate supply for the maintenance of all volcanic phenomena. Or, if the earth itself is equivalent to a huge meteorite, as many thinkers have supposed, the analogy between it and the smaller bodies accounts for nearly, if not quite, all volcanic gases. From this point of view they are occlusions, forced out by pressure and the resulting mechanical heat. Between this suppo- sition and that of Chamberlin there is little essential difference, at least upon the chemical side of the problem. The analogy between the expulsion of a gas from the interior of our globe and its evolution from meteorites has been well developed by G. Tschermak , 2 who regards volcanism as a cosmic phenomenon, of which the typical example is fco be found in the terrific gaseous upheavals that are seen on the surface of the sun. For each of the theories so far proposed relative to the origin of volcanic gases strong arguments can be adduced, and no one should be exclusively adopted. The phenomena are probably complex, and many activities contribute to their development. Some gas must be derived from reactions like those described by Travers and Gautier; some must originate from percolating waters; and a portion of the supply may possibly come from deep-seated sources. Whether we assume that the earth was once a molten globe or that it was formed by the accretion of meteoric masses, gases must be retained within its interior, and their escape from time to time would seem to be unavoid- able. Molten matter, whether metallic or stony, is known to dis- solve gases in large amounts, as silver dissolves oxygen , 3 and they are expelled in great measure during solidification. They are, moreover, expelled explosively, a fact which can be verified in any laboratory; but that the expulsion is complete is extremely improbable. Some gas, it may be much or little, is retained by the solid mass, and modi- fies its properties. All of these elements contribute to the phenomena of volcanism, but their relative magnitudes can not now be evaluated. Speculation upon them may help to stimulate research, but so long as the temperatures and pressures within a volcano are unmeasured the problems suggested by the hypotheses must remain unsolved. The question of volcanic temperatures, of which more will be said in the next chapter, is particularly important in the investigation of 1 Ann. Chem. Pharm., vol. 163, 1872, p. 250. A similar observation by M. Berthelot is recorded by A. Daubr^e, Compt. Rend., vol. 74, 1872, p. 1541. 2 Sitzungsb. Akad. Wien, vol. 75, 1877, p. 151. 3 One volume of molten silver can absorb 22 volumes of oxygen, which escapes explosively when the metal cools. This ‘'spitting” of melted silver is familiar to all assayers. VOLCANIC GASES AND SUBLIMATES. 289 volcanic explosions. The latter are due in part to cooling and the violent expulsion of gases following relief of pressure, but chemical combination may also be manifest in them. If the temperature in the depths of a volcano is high enough to dissociate water into its elements, then the issuing gases will form an explosive mixture of tremendous energy. The moment such a mixture reached the surface of the molten lava it would have become cool enough to ignite, and the characteristic detonations would follow. Hydrogen alone, emerg- ing into the air, might form with the latter a similar mixture and produce the same phenomena. E. W. von Siemens, 1 observing a series of explosions at Vesuvius, ascribed them to this cause. That hydro- gen does issue from volcanoes is established; under certain conditions it burns quietly, and under others it gives rise to explosions; but in either case it develops much heat and so retards the cooling of its surrounding matter. One gram of hydrogen, burning to form water, liberates a quantity of heat represented by 34,000 calories; that is, it would raise the temperature of 34,000 grams of water from 0 Q to 1° C. This reaction alone, this combustion of hydrogen in air, evidently plays a very large part in the thermodynamics of volcanism. SUMMARY. That the volcanic gases appear in a certain regular order has been shown by the various researches upon their composition, and espe- cially by the labors of Deville and Leblanc. What, now, in the light of all the evidence, is that order, and what do the chemical changes mean? First. The gases issue from an active crater at so high a tempera- thre that they are practically dry. They contain superheated steam, hydrogen, carbon monoxide, methane, the vapor of metallic chlorides, and other substances of minor importance. Oxygen may be present in them, with some nitrogen, argon, sulphur vapor, and gaseous com- pounds of fluorine. Second. The hydrogen burns to form more water vapor, and the carbon gases oxidize to carbon dioxide. From the sulphur, sulphur dioxide is produced. The steam reacts upon a part of the metallic chlorides, generates hydrochloric acid, and so acid fumaroles make their appearance. Third. The acid gases of the second phase force their way through crevices in the lava and the adjacent rocks, and their acid contents are consumed in effecting various pneumatolytic reactions. The rocks are corroded, and where sulphides occur hydrogen sulphide is set free. If carbonate rocks are encountered, carbon dioxide is also liberated. i Monatsb. K. prouss. Akad., 1878, p. 558. 97270°— Bull. 616—16 19 290 THE DATA OF GEOCHEMISTRY. Fourth. Only steam with some carbon dioxide remains, and even the latter compound soon disappears. This seems to be the general course of events, although it is modi- fied in details by local peculiarities. All of the substances enumer- ated in the lists of gases and sublimates given in the earlier portions of this chapter may take part in the reactions, but they do not seriously affect the larger processes which have just been described. The order is essentially that laid down by Deville and Leblanc, except that the early evolution of hydrogen and carbonic oxide is taken into account. The current of events may be disturbed, so to speak, by ripples and eddies — that is, by subsidiary and reversed reactions — but its main course seems to be clearly indicated . 1 1 For a summary of our knowledge concerning the magmatic gases previous to the work of Bran and Chamberlin, see F. C. Lincoln, Econ. Geology, vol. 2, 1907, p. 258. Lincoln gives a good table of analyses and proposes a classification of the volcanic exhalations. For a theoretical discussion relative to “gas mineralizers ” in magmas see P. Niggli, Zeitschr. anorg. Chemie, vol. 75, p. 161 , and vol. 77, 1912, p. 321. Also Centralbl. Min., Geol. u. Pal., 1912, p. 321; and Geol. Rundschau, vol. 3, 1912, p. 472. CHAPTER IX. THE MOLTEN MAGMA. TEMPERATURE. In the chapter upon volcanic gases the question of temperatures was purposely left vague, and only the bare fact that they must be high was taken into account. For an intelligent study of the mag- mas, however, some more definite estimates of temperatures are essen- tial, even though their inferior limits can alone be determined with any degree of certainty. We can measure the temperature at which lavas and their component minerals fuse, under ordinary conditions of pressure; but these melting points are modified by various agencies within the depths of the earth, and it is not yet possible to strike a definite balance between the opposing forces. By pressure, which steadily increases as we descend into the earth, the melting points must be raised , 1 but on the other hand the gases that we know to be present in the molten mass tend to lower them, and the latter tend- ency is probably the stronger. The fact that pressure tends to prevent the escape of dissolved vapors, and so to increase fluidity, must also be taken into account. It should be remembered, more- over, in any' reasoning upon the unerupted magma, that the tempera- ture at which it can retain the liquid state is a minimum, and that actually it may be very much hotter. The temperature, furthermore, is believed to increase with the depth; but we can do no more than to surmise what the conditions may be miles below the apparent surface of the lava column . 2 Although the characteristics of the in- dividual rock-forming minerals will not be generally discussed until the next chapter is reached, our knowledge of their melting points may properly be summed up here. It is only within recent years that anything like accurate measurements of high temperatures have been possible, and therefore the few and scattered older data can be ignored . 3 The development of the thermocouple by C. Barus in the United States Geological Survey, and by H. Le Chatelier in France, and the use of the Seger cones in the ceramic industry, have 1 Estimates of the change in fusibility due to pressure have been made by Lord Kelvin, Philos. Mag., 5th ser., vol, 47, p. 66; C. E. Stromeyer, Mem. Manchester Lit. Philos. Soc., vol. 44, No. 7, 1900, and J. H. L. Vogt, Min. pet. Mitt., vol. 27, 1908, p. 105. The fundamental data, however, are few and unsat- isfactory. On the influence of pressure in producing chemical changes in deep-seated rocks, see J. W. Judd, Jour. Chem. Soc., vol. 57, 1890, p. 404. 2 For estimates of temperatures far within the earth, see Clarence King, Am. Jour. Sci., 3d ser., vol. 45, 1893, p. 7; O. Fisher, idem, 4th ser., vol. 11, 1901, p. 414; F. R. Moulton, cited by T. C. Chamberlin, Jour. Geology, vol. 5, 1897, p. 674; and A. C. Lunn, in Chamberlin and Salisbury’s Geology, vol. 1, 1904, p. 552. All the estimates reach exceedingly high figures, but they are based upon very doubtful extrapolations. It is conceivable that the increase of temperature with depth may reach a limit which it can not exceed. 3 See, for example, A. Schertel and T. Erhard, Beiblatter, 1879, p. 347; and Schertel, idem, 1880, p. 542. 291 292 THE DATA OF GEOCHEMISTRY. placed high-temperature pyrometry upon a new footing and have made practicable the class of determinations which we now require. In 1891 J. Joly 1 described an instrument (the meldometer) by means of which the melting points of minerals could be rapidly and easily determined, and several years later R. Cusack 2 reported a considerable number of measurements made with its aid. The in- strument consisted of a thin ribbon of platinum, upon which the min- eral to be examined, in very fine powder, was placed. The particles of mineral dust were observed with a microscope; the ribbon was heated with an electric current; and from the expansion of the plati- num, which was measurable, the temperature was ascertained. For the method by which the meldometer was calibrated the original memoir may be consulted. C. Doelter, 3 in recent years, has made many melting-point determi- nations by means of a thermoelectric couple. In his earlier work the minerals were fused in a gas furnace; later an electric furnace was used. The determinations by A. Brun 4 were published in 1902 and 1904. His fusions were effected in a muffle furnace, heated by a mixture of oxygen and illuminating gas, and the temperatures were measured by comparison with Seger cones. The crystallized mineral was mounted on a slender peduncle of platinum, and so placed that it was heated by radiation from the walls of the muffle out of contact with the flame. In all of the determinations represented by the foregoing investiga- tions the subjective element has been large. The tested samples were watched and the human eye was trusted to determine when soften- ing began and when fusion was complete. Greater exactness has been secured in the researches conducted by A. L. Day and his colleagues 5 6 in the geophysical laboratories of the United States Geological Survey and the Carnegie Institution upon almost ideally pure 1 Proc. Roy. Irish. Acad., 3d ser., vol. 2, 1891, p. 38. 2 Idem, vol. 4, 1896, p. 399. s Min. pet. Mitt., vol. 20, 1901, p. 211; vol. 21, 1902, p. 23; vol. 23, 1903, p. 297; Sitzungsb. Akad. Wien, vol. 114, 1905, p. 529; vol. 115, Abth. 1, July, 1906. The determinations cited are from his third paper. * Arch. sci. phys. nat., 4th ser., vol. 13, 1902, p. 552; vol. 18, 1904, p. 537. For the details of Bran’s deter- minations, see his volume Recherches sur l’exhalaison volcanique, Geneva, 1911. There are also some determinations by W. C. Roberts- Austen, cited by Lord Kelvin, Philos. Mag., 5th ser., vol. 47, 1899, p. 66 others by J. H. L. Vogt, published in part 2 of Die Silikatschmelzlosungen, and a few by W. Hempel; Ber. V Internat. Kong, angew. Chemie, vol. 1, 1904, p. 725. For data on shales and clays, see W. C. Heraeus, Zeitschr. angew. Chemie, 1905, p. 49. For several rare minerals, see H. L. Fletcher, Sci. Proc. Royal Dub- lin Soc., vol. 13, 1913, p. 443. For Japanese minerals, Y. Yamashita and M. Majima, Sci. Rept. Tohuku Univ., vol. 2, 1913, p. 175. On methods, with a compilation of data, A. L. Day, Fortschr. Min., Kryst. u. Pet., vol. 4, 1914, p. 115. 6 A. L. Day and E. T. Allen, Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 93, on the feldspars. E. T. Allen and W. P. White, idem, vol. 21, 1906, p. 100, on wollastonite. A. L. Day and E. S. Shepherd, idem, vol. 22, 1906, p. 265, on the lime-silica series. E. T. Allen, F. E. Wright, and J. K. Clement, idem, vol. 22, 1906, p. 385, on magnesium metasilicate. E. T. Allen and W. P. White, idem, vol. 27, 1909, p. 1, on diop- side, etc. E. S. Shepherd and G. A. Rankin, idem, vol. 28, 1909, p. 293, on binary systems of alumina with silica, lime, and magnesia. For a summary of these determinations, with corrections, see A. L. Day and R. B. Sosman, Am. Jour. Sci., 4th ser., vol. 31, 1911, p. 341. The corrected figures are given in the following table. Later papers by N. L. Bowen, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 554; vol. 38, 1914, p. 218, and N. L. Bowen and O. Andersen, idem, vol. 37, 1914, p. 487, are also important. Mixtures similar to the last have also been studied by R. Rieke, Chem. Abst., vol. 2, 1908, p. 985, from Stahl u. Eisen, vol. 28. THE MOLTEN MA&MA. 293 artificial minerals, and with, thermoelectric couples which had been calibrated by comparison with the standards at the Physikalische Reichsanstalt at Berlin. In these measurements the melting points were determined by noting the exact temperatures at which abrupt absorptions of heat occurred, thus avoiding errors of judgment. From the great mass of data now available I have compiled the following table, which well exhibits the great divergence between the older and the newest determinations. The table might be greatly extended, but so many of the published figures relate to unanalyzed minerals that their value is problematical. Additional data will be given in Chapter X, in describing individual species. Melting points ( °C .) of various minerals , as determined by different investigators. Feldspars and feldspatkoids. Mineral. Joly. Cusack. Doelter. Brun. Day et al. AnortMte, natural 1, 165-1, 210 1, 490-1, 520 1, 544-1, 562 A north it, a artificial 1, 550 1, 516 1, 477 An 5 Ab 1? artificial An 2 Ab!, artificial Labradorite Andesine 1, 230 1, 223-1, 235 1, 040-1, 210 1, 155-1, 185 1, 370 1, 280 ArijAbj, artificial 1, 430 1, 375 a 1, 340 An 1 Ab 2 , artificial An 1 Ab 3 , artificial Oligoclase 1, 220 1, 175 1, 135-1, 185 1, 115-1, 170 1, 185-1, 220 1, 275-1. 315 1, 105-1, 125 1, 260 1, 259 Albite Orthoclase 1, 172 Leu cite 1, 298 1, 059-1, 070 1, 410-1, 430 1, 270 Nepheline, artificial 1, 526 a Approximate. Viscosity prevents exact measurements. Miscellaneous minerals. Mineral. Cusack. Doelter. Brun. Day et al. Enstatite 1, 375-1, 400 MgSi0 3 , artificial 1, 557 Wollastonite a 1, 203-1, 208 1, 230-1, 255 1, 366 1, 515 1, 270 CaSi0 3 , artificial 1,540 & 1, 391 Diopside, natural Diopside, artificial 1, 187-1, 195 1, 135-1, 265 Augite 1. 187- 1, 199 1, 219-1, 223 1. 187- 1, 200 1, 342-1, 378 1, 425 1, 085-1, 200 1, 200-1, 220 1, 065-1, 155 1, 265-1,410 1, 230 1, 270 1, 060-1, 070 1, 750 1, 780 Tremolite Hornblende Olivine Quartz c 1, 625 Magnetite 1, 190-1, 225 1, 350-1, 400 Hematite 1, 300 1, 270 Fluorite d 1, 387 1, 816 Sillimanite a Wollastonite lias no true melting point. At 1,190° it passes into the pseudohexagonal form, which melts at 1,540°. b A much lower value, 1,225°, was given by Vogt. c More properly silica. Quartz is transformed into cristobalite or tridymite at about 800°, and has no true meltmg point of its own. Roberts- Austen gives the melting point of silica as 1,775° and Hempel as 1,685°. Alumina (corundum?) melts, according to Hempel, at 1,880°, magnesia at 2,250°, and lime at 1,900°. According to C. W. Kanolt (Jour. Washington Acad. Sci., vol. 3, 1913, p. 318), A1 2 0 3 melts at 2,050°, MgO at 2,800°, CaO at 2,570°, and Cr 2 0 3 at 1,990°. O. Boudouard (Jour. Iron and Steel Inst., 1905, pt. 1, p. 350) puts the melting point of silica at 1,830°. According to P. D. Quensel (Centralbl. Min., Geol. u. Pal., 1906, pp. 657, 728), tridymite melts as low as 1,560°, and shows incipient fusion at 1,500°. d Private communication from A. L. Day; determined on the natural mineral. 294 THE DATA OF GEOCHEMISTRY. A few other interesting determinations of melting point have been given by G. Stein, who used the Wanner pyrometer. 1 Quartz, or rather silica, became a viscous semifluid at 1,600°, and was com- pletely liquid at 1,750°. Above the latter temperature it sublimes. For several artificial silicates, corresponding to natural minerals, the following melting points were observed: CaSi0 3 , 1,512°; MgSi0 3 , 1,565°; FeSi0 3 , 1,500° to 1,550°; MnSi0 3 , 1,470° to 1,500°; Mg 2 Si0 4 , below 1,900°; Zn 2 Si0 4 , 1,484°. There is also a research by E. Dittler, 2 in Doelter’s laboratory, in which the work of Day and his colleagues is criticized, 3 and the attempt is made to show that their melting points are much too high. For example, Dittler gives 1,310° as the melting point of artificial anorthite, and 1,200° as that of the natural mineral. What Dittler has observed, however, seems not to be the melting points as defined by Day, but rather temperatures at which the crystallized substances begin to show transitions into the very viscous amorphous forms. This is suggested by the second paper of Brun, in which he gives the following determinations: Artificial anorthite melts, as measured by a calorimetric method, between 1,544° and 1,562°. Japanese anorthite fused at 1,490°, albite at 1,259°, olivine at about 1,750°, wollastonite at 1,366°, and the hexagonal calcium metasilicate at 1,515°. In the glassy state the artificial anorthite begins to show deformation at 1,083° to 1,110°, and it crystallizes between 1,210° and 1,250°. The albite glass softens at 1,177°. These lower temperatures accord fairly with those determined by Cusack, Doelter, and Dittler, who seem to have ob- served them rather than the true melting points. Other discordances are due to differences between the substances examined, for natural minerals are rarely pure, and in the pyroxene-hornblende-olivine series the variations due to isomorphism are very large. One augite, for example, contains much, another little, iron; calcium and magne- sium also vary in then proportions, and so on. In these series, gen- erally speaking, the melting point falls as the percentage of iron increases. The presence of water in a mineral has also a lowering effect upon the melting point, and this impurity is not often entirely absent. The figures given, therefore, do not, except in those from the Geophysical Laboratory and in one or two other cases, refer to ideally pure compounds, but to the natural minerals with all their defects of composition. They help us to form some idea of the temperatures which govern volcanic phenomena, but we can not reason upon them as if they were precise and definite. They also furnish us with some checks that we can use in studying- the order of formation of minerals when a molten lava cools, although here again 1 Zeitschr. anorg. Chemie, vol. 55, 1907, p. 159. 2 Idem, vol. 69, 1911, p. 273. 3 For a reply to criticisms see Day and Sosman, Am. Jour. Sci., 4th ser., vol. 31, 1911, p. 341. THE MOLTEN MAGMA. 295 the data should be handled with great caution. A comparison of the different figures for the melting point of the same mineral, say for leucite or olivine, will show how great the existing uncertainties really are. Furthermore, many of the published melting points have no real significance. Some of the minerals for which melting points have been recorded break down into other substances before or during fusion, a fact of which Brun has taken notice in a number of instances. The micas, for example, for which Doelter gives several determina- tions, lose water and are transformed into other silicates or mixtures of silicates, whose precise character is unknown. Garnet, when fused, also splits up into two or more compounds, and in such cases the recorded melting points are meaningless. In the geological interpretation of the melting points there is one particularly dangerous source of error. We must not assume that the temperature at which a given oxide or silicate melts is the tem- perature at which a mineral of the same composition can crystallize from a magma. Many substances exist in more than one modifica- tion, and certain forms, which often correspond to natural minerals, are developed only at temperatures far below the apparent points of fusion. Quartz, for example, ceases to be quartz and becomes tridy- mite long before it fuses; wollastonite is transformed into a pseudo- hexagonal substance which is unknown as a mineral species, and the melting point of magnesium metasilicate, under ordinary conditions, is not that of the orthorhombic enstatite, but of a monoclinic variety. In these instances, which will be taken up in detail in the next chap- ter, the transition temperatures, at which one form changes to another, are geologically as important as the melting points, and perhaps of even greater value. They are the temperatures above which the several species can not form, and therefore they are of the utmost significance. Silica crystallizes as quartz only below 800°; wollastonite can not exist above 1,190°; and so the formation of either mineral in a rock tells us something of the conditions under which it solidified. As yet the data of this class are unfortunately few, but their number is likely to become much greater within the near future. 1 For the direct study of the igneous rocks themselves, the available melting-point measurements are very few. Mixtures, such as rocks, unless they happen to be eutectic, have no distinct melting points, and two temperatures at least should be determined for each example. 1 For a discussion of the application of these temperature relations to geological occurrences see J. Koenigsberger, Econ. Geology, vol. 7, 1912, p. 676, and Neues Jahrb.. Beil. Band 32, 1911, p. 191. 296 THE DATA OF GEOCHEMISTRY. The following temperatures, observed by Doelter, 1 will serve to illustrate this point: Melting 'points (°C.) of various igneous rocks. Rock. Softens. Becomes fluid. Granite, Predazzo 1, 150-1, 160 1, 115-1, 125 1,030-1,060 962-970 992-1, 020 995-1, 000 1,060 1,040-1,060 1,240 1,190 1, 080-1, 090 1, 010-1, 040 1,060-1,075 1, 050-1, 060 1,090 1, 060-1, 100 Monzonite, Fredazzo Lava, Vesuvius Lava, Etna Basalt, Ttemagen Limburgite Phonolite . .. Nepheline syenite According to A. Brun, 1 2 the basalt from Stromboli begins to soften at 1,130°, and at 1,170° it becomes pasty. The still molten rock con- tains crystals of augite whose melting point he places at 1,230°. The temperature at which the basalt solidified, therefore, cannot exceed that figure, and may have been much lower. Similar reasoning has been employed by C. Doelter, 3 based upon the presence of leucite in Yesuvian lava. Doelter, however, assigned to leucite a melting point which is certainly too low, 4 and his computations, which must be revised, need not be considered further. All we can now say with certainty is that the temperature of an emerging lava must be above that at which it begins to solidify. That temperature is rarely, if ever, below 1,000° C., and the actual temperature not long before emission may be hundreds, perhaps a thousand, degrees higher. The temperature of the lava pool at Kilauea, as determined by Day and Shepherd, was ahnost exactly 1,000°. Lava at Torre del Greco, says A. Geikie, 5 fused the sharp edges of flints and decomposed brass, the copper actually crystallizing. From its effect on flint, it would seem that its temperature could hardly be below 1,600°, at which point silica softens. If, however, the apparent fusion was due to a solvent action of the molten lava, the argument in favor of a high tempera- ture breaks down. A careful study of the conditions under which silicates have been sublimed at Vesuvius might shed much light on the problem. 6 1 Mia. pet. Mitt., vol. 21, 1902, p. 23. J. A. Douglas (Quart. Jour. Geol. Soc., vol. 63, 1907, p. 145), has also made a number of similar determinations, and has measured the increase of volume which minerals exhibit in passing from the crystalline to the glassy phase. Such an increase is probably the rule, l ut A. Fleischer (Zeitschr. Deutsch. geol. Gesell., vol. 57, 19C5, p. 201 (Monatsb.); vol. 59, 1907, p. 122) has shown that molten basalt and some slags expand on solidification. See also A. Earker, Natural history of igneous rocks, p. 158. 2 Arch. sci. phys. nat., 4th ser., vol. 13, 1902, p. 367. s Sitzungsb. Akad. Wien, vol. 112, 1903, p. 681. 4 See preceding table of melting points. Preliminary experiments by A. L. Day have shown that the melting point of leucite is certainly above 1,500°. & Text-book of geology, 4th ed., p. 304. 6 On temperatures at Etna see G. Platania, Atti R. accad. Lincei, ser. 5, vol. 21 (1), 1912, p. 499. The figures obtained and those cited from others are very variable. Variations in the composition of the lava, and especially in its content of gases, will account for some of the discrepancies. THE MOLTEN MAGMA. 297 INFLUENCE OF WATER. So far the measurements cited in this chapter relate to dry fusion or to the fusion of minerals containing only insignificant quantities of hygroscopic water. Within a volcano, apparently, the conditions are quite different, and there the presence of water must be taken into account, together with the gases which are so powerfully oper- ative in producing explosions. The magma, before eruption, is some- thing very different from the smoothly flowing stream of lava, for it is heavily charged with aqueous vapor and other gases, under great pressure, exactly as the soda water in an ordinary siphon bottle is loaded with carbon dioxide. When the pressure is released the gases escape with explosive force, carrying the liquid matter with them. 1 In the eruption of a volcano this process produces a great quantity of fiery spray, which solidifies in the form of volcanic ash, while other portions of the foaming surface of the lava cool to pumice. When the lava stream itself appears its effervescence has largely ceased, and it exhibits the ordinary phenomena of a cooling liquid. The condition of the water which is contained within a magma is perhaps best explained by certain experiments of C. Barus, 2 who found that colloid substances, in presence of solvents, swell up enor- mously, and that at high temperatures the swollen coagulum passes into a clear and apparently homogeneous solution. This observation he’ extended to mixtures of ordinary soft glass and water, which he heated in closed steel tubes to 210° C. Under these conditions 210 grams of glass with 50 grams of water formed a resinous opalescent mass, in which all the water was absorbed. This substance, to which Barus gave the name of “water glass/’ when heated in air, swells up enormously, loses water, and forms a true pumice. By ordinary exposure to air the substance slowly disintegrates. Salts dissolved in the water do not enter the glass, which acts in that respect like a semipermeable membrane. Hard glasses are more refractory; but it is probable that at the temperatures and pressures existing within a volcano, all of the silicates would act in a similar way and give similar solutions. This may enable us to form some notion of the unerupted magma, with its dissolved gases, and the changes which it undergoes when the pressure upon it is relieved. One effect of the water would be to reduce the temperature at which liquidity could be maintained. An obsidian, in presence of water, was found by 1 This comparison of a volcano with a bottle of soda water or champagne has been developed by S. Meunier. He assumes that the water was originally occluded or combined in the rocks and when the latter, by displacement, are brought into the region of high temperature, their aqueous content is set free and an explosion becomes possible. See La Nature, vol. 30, pt. 1, 1902, p. 386. Also Jour. Washington Acad. Sci., vol. 4, 1914, p. 213> 2 Am. Jour. Sci., 4th ser., vol. 9, 1900, p. 161. The name “water glass,” as used by Barus, is unfortunate, for it already belonged to the soluble alkaline silicates and had been in current use for many years. 298 THE DATA OF GEOCHEMISTRY. Barus to fuse at about 1,250°, while the resulting pumice melted at 1,650°, approximately. 1 MAGMATIC SOLUTIONS. So far as we can determine, then, the magma, previous to eruption, is a mass of rock-forming matter, in a state of fusion, and heavily charged with gases under enormous pressure. To what extent and how its temperature may vary we do not know, but the pressure must fluctuate widely. It is through overcoming pressure that eruptions become possible. Then gases and water are largely expelled, and a fluid or viscous lava, very different from the original magma, remains. By pressure, furthermore, the temperature needed to produce com- plete fluidity is raised, and this fact is emphasized by the phenomena of resorption. A mineral — hke quartz, for example — may crystallize within a viscous magma, but when the pressure is reduced its temper- ature of fusion falls, and partial or complete re-solution may take place. These partly redissolved minerals are familiar objects to the petrologist. 2 Whether the magma itself, at great depths, is homogeneous or not is an open question, but it is not emitted homogeneously. Different lavas issue, not only from neighboring vents, but successively from the same opening during a series of eruptions. To determine the cause of these differences is one of the great problems of petrology, and many solutions of it have been proposed, discussed, and either abandoned or partly accepted. To discuss these attempts in detail does not fall within the scope of this memoir, but the evidence upon which they rest, so far as it touches chemistry, must be briefly considered. 3 From a physicochemical point of view, a molten rock is to be regarded as a solution, behaving in all essential particulars exactly hke any other solution. One or more minerals are dissolved in another, as salt dissolves in water; or, better, they are mutually dissolved, hke a mixture of water and alcohol. We can not ready say that in such a mixture one substance is the solvent and the others are the solutes, for the distinction is not a sound one, however con- 1 Compare F. Guthrie, Philos. Mag., 5th ser., vol. 18, 1884, p. 117, on the change from obsidian to pumice by extrusion of water. 2 A good example of the resorption of olivine in a basalt is given by C. N. Fenner, Am. Jour. Sci., 4th ser., vol. 29, 1310, p. 230. The author discusses other physicochemical relations of a basaltic magma at some length. 3 For good summaries on magmatic differentiation, see J. P. Iddings, The origin of igneous rocks: Bull. Philos. Soc. Washington, vol. 12, 1892, p. 89; W. C. Brogger, Die Eruptivgesteine des Kristianiagebietes, pt. 3, 1898, p. 334; and F. Loewinson-Lessing, Compt. rend. VII Cong. g6ol. intemat., 1897, p. 308. These are only a few among many memoirs dealing more or less fully with the subject. Loewinson- Lessing’s paper is rich in literature references. For a criticism adverse to the idea of magmatic differentiation see F. Fouqu4, Bull. Soc. min., vol. 25, 1902, p. 349. On magmatic differentiation in Hawaii, see R. A. Daly, Jour. Geology, vol. 19, 1911, pj»289. THE MOLTEN MAGMA. 299 venient it may be in ordinary cases. 1 The different molten substances dissolve one another, and if there are any limits to their miscibility they have not been determined. I speak now, of course, with refer- ence to the constituents of an ordinary fluid lava, and these are mostly silicates — that is, metallic salts. The more familiar aqueous solutions of salts are electrolytes, and in them the compounds are believed to be dissociated into their ions. This dissociation is complete only at infinite dilution ; in concentrated solutions it is partial, and in a saturated solution its amount may be comparatively small. In a molten magma probably all of these con- ditions hold, for as a solution it is dilute with respect to its minor components, but highly concentrated as regards the more essential minerals. As a solution of apatite or rutile it may be very weak; as a solution of quartz, feldspar, or pyroxene, very strong. It is, however, a conductor of electricity, and, therefore, if the analogy between it and ordinary solutions is valid, it is at least partially ionized. This is the view adopted by C. Barus and J. P. Iddings, 2 who studied the electrical conductivity of three molten rocks, for which the following condensed descriptions may be cited here: Melting points and silica content of three igneous rocks. Rock. Approxi- mate melt- ing point. Percentage of Si 02 . Basalt 1,250 1,400 1, 500 48.49 Hornblende-mica porphyry 61. 50 Rhyolite 75.50 At 1,300° the basalt was quite fluid, but at 1,700° the rhyolite was still viscid, and yet the conductivity increased with the viscosity and with the silica, in spite of the fact that silica alone is probably an insulator. In other words, the fused rocks are electrolytes, and the silicates in them are probably more or less dissociated into their ions. 3 What these. ions are we do not yet know; but their ultimate identification is not hopeless. The extent of the ionization is also unknown, but its existence seems to be established. Furthermore, 1 G. F. Becker (Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 3, 1901, p. 519) proposes to regard the eutectic mixtures as the true solvents, and the minerals which separate from them as the solutes. This suggestion has attracted much attention; but it can not be fully utilized until we know what the eutectics really are. 2 Am. Jour. Sci., 3d ser., vol. 44, 1892, p. 242. 3 The coexistence in certain rocks of antagonistic minerals like quartz and magnetite may be an evidence of dissociation. They should react to form a silicate of iron, but we can readily imagine a highly viscous melt as solidifying so rapidly that all of the ions are unable to find their proper partners. The free oxides therefore appear in the solid product. I offer this merely as a suggestion. H. J. Johnston-Lavis, Bull. Soc. beige gdol., vol. 22, 1908, p. 103, has attributed the quartz in a particular basalt to included gneiss. Doelter (Sitzungsb. Akad. Wien, vol. 113, 1904, p. 169) ascribes the early separation of oxides and alumi- nates from cooling magmas to dissociation. 300 THE DATA OF GEOCHEMISTRY. since the several silicates are present in a magma in different degrees of concentration, they must be differently ionized, and some of them to a much greater extent than others. When a salt dissolves in water the temperature of solidification is changed. Water, for example, freezes at 0° C., but the addition of 23.6 per cent of sodium chloride to it reduces the melting or solidifying point to —22°. This depression of the melting point is quite a general phenomenon, and from it, by formulae which need not be considered here, the molecular weight of the dissolved sub- stance can be calculated. In alloys a similar change can be observed, and in some cases it is very striking; the well-known fusible alloys, for instance, melt at temperatures below the boiling point of water. An igneous rock, so far as our data now go, exhibits the same peculiarity, and becomes fluid at temperatures below the average meiting point of its constituent minerals, and sometimes lower than the lowest among the latter. Doelter’s figures, as cited on page 296, serve to illustrate this point, although the depression is not so marked as in the more familiar cases just mentioned. The experiments by Michaela Vucnik 1 and Berta Vukits, 2 who fused together minerals of supposedly known melting points and observed those of the mixtures, tell the same story. In some cases, however, the interpretation of the observations is complicated by chemical reactions, which pro- duced new salts; and it is also affected by the liability of glasses to supercooling. Attempts to compute molecular weights from the observed depressions gave unsatisfactory results, and led to no defi- nite conclusions. 1ST. V. KultaschefFs investigations, 3 although not rigorously com- parable with natural phenomena, point in the same direction. Mix- tures of Na 2 Si0 3 and CaSi0 3 were studied, the first salt melting at 1,007° and the second at a temperature above 1,400°. 4 A mixture of 80 per cent of the sodium salt with 20 per cent of the calcium com- pound fused at 938°, and even greater depressions were produced by additions of the still less fusible silica. Upon adding only 6.5 per cent of silica to the sodium silicate, the melting point was reduced to 820°. It was also found that the two silicates united to form at least two double salts, a fact which complicates the interpretation of the phenomena. 5 1 Centralbl. Min., Geol. u. Pal., 1904, pp. 295, 340, 364. 2 Idem, pp.. 705, 739. 3 Zeitschr. anorg. Chemie, vol. 35, 1903, p. 187. 4 1,540° according to Allen and White. See table of melting points, p. 293. & A similar study of several binary mixtures of silicates is reported by R. C. Wallace, Zeitschr. anorg Chemie, vol. 63, 1909, p. 1. The mixtures examined, however, with one or two exceptions, do not corre- spond to natural minerals. THE MOLTEN MAGMA. 301 EUTECTICS. When a fused rock, or mixture of similar character, solidifies, it can do so in either one of two ways. It may solidify as a unit, forming a glass, in which no individualization of its constituents can be detected, or it may solidify as a mass of crystalline minerals, each one exhibiting its own peculiarities. Between these extremes many intermediate conditions, due to partial crystallization, are possible, ranging from glass containing a few crystals to a crystalline mass with some glassy remainder left over — that is, both processes may go on in the same cooling magma, and both, of course, incompletely. The more viscous the lava the less easily its materials can crystallize, and hence glasses are most commonly derived from magmas rich in silica. Obsidian has essentially the composition of rhyolite. Let us now consider what will happen when a solution solidifies to a crystalline aggregate. Take for example a solution of common salt in water, which freezes at — 22° C. with a definite proportion — namely, 23.6 per cent — of sodium chloride in the mixture. Upon cooling such a solution, if less than that proportion of salt is present, ice will crystallize first, but when the indicated concentration and temperature have been reached the entire mass — salt and water — will solidify. If, on the other hand, salt is in excess of 23.6 per cent, its hydrate, NaC1.2H 2 0, will first appear and continue to be deposited until the point of equilibrium has been attained. Then the same mix- ture will solidify as in the other case. This minimum temperature, with its definite, corresponding concentration of salt and water, is known as the eutectic point, and at that point the solution and the solid have the same composition. 1 Above the eutectic point either salt or water may crystallize out, that substance being first deposited which is in excess of the eutectic ratio — the ratio, that is, of 23.6 NaCl to 76.4 H 2 0. In the freezing of sea water the separation of nearly pure ice is seen, because the water is largely in excess of the eutectic proportions. When two salts are fused together and allowed to solidify, the same order of phenomena appears, provided that certain conditions are satisfied. First, the fused salts must be miscible — that is, soluble in one another. If this condition is not fulfilled the melt will separate into layers. Secondly, they must not be capable of acting upon each other chemically, for in that case new compounds are produced. Finally, they should not be isomorphous salts, for then no eutectic mixture is possible. The feldspars albite and anorthite, for example, crystallize togther in all proportions, and the melting points of the 1 F. Guthrie regarded these saline mixtures with water as definite compounds, which he termed cryohy- drates. See Philos. Mag., 4th ser., vol. 49, 1875, pp. 1, 206, 266; 5th ser., vol. 17, 1884, p. 462. See also M. Roloff, Zeitschr. physical. Chemie, vol. 17, 1895, p. 325. 302 THE DATA OF GEOCHEMISTRY. mixed crystals form a series with no eutectic depression. This differ- ence between isomorphous and eutectic mixtures is fundamental. Since, now, the fusing point of a lava generally falls below the average melting point of its constituent minerals, the foregoing con- siderations may be applied to its investigation. Some of its compo- nents will form isomorphous mixtures, but a part of it will represent eutectic proportions which differ with the varying composition of different rocks. In each case the substances that are in excess of the eutectic ratios are likely to crystallize first, and the eutectic mixture itself will probably be found in the groundmass, or solidi- fied mother liquor, from which the crystals have separated. From this point of view the study of the eutectics becomes fundamentally important in the study and classification of igneous rocks, for they chiefly determine the character and order of deposition of the pheno- crysts. There are doubtless other factors in the problem, but this one is the most fundamental and characteristic. So far none of the eutectics in question have been positively identified, although various attempts to indicate them are on record, with results which may or may not be verified. In Kultascheffs experiments with sodium and calcium silicates two eutectic points were noted, which represented, however, not a single natural mixture, but a series of artificial mixtures wherein both of the original compounds and two double salts took part. H. O. Hofman’s work 1 on artificial slags, containing iron and calcium silicates, also tells us something about possible eutectic points, and other valuable data are given in the memoir by A. L. Day and E. S. Shepherd 2 on the compounds of lim e and silica. The mixtures studied in the latter investigation, how- ever, do not correspond to any known natural associations. F. Guthrie, 3 to whom the expression “eutectic” is due, was the first to point out the applicability of his researches to the study of igneous rocks, and of late years his suggestions have received much attention. J. J. H. Teall 4 was one of the first to develop the subject, and he indicated a micropegmatite, with 62.05 per cent of feldspar and 37.95 per cent of quartz, as a possible eutectic mixture. This possibility has been discussed by several writers, and especially by J. H. L. Vogt, 5 who regards a mixture of 74.25 per cent of orthoclase with 25.75 per cent of quartz as the true eutectic in this particular instance, and shows that it is very close to the average micropegmatite in composi- 1 Technology Quart., vol. 13, 1900, p. 41. 2 Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 265. 3 Philos. Mag. , 4th ser., vol. 49, 1875, p. 20. 4 British Petrography, 1888, pp. 395-419. 5 Die Silikatschmelzlosungen , pt. 2, 1904, pp. 113-128. See also Vogt, Min. pet. Mitt., vol. 24, 1906, p. 437; vol. 25, 1906, p. 361; vol. 27, 1908, p. 105. A. C. Lane, Jour. Geology, vol. 12, 1904, p. 23. H. E. Johansson, Geol. Foren. Forhandl., vol. 27, 1905, p. 119; and A. Bygd6n, Bull. Geol. Inst. Upsala, vol. 7, 1904-5, p. 1. The subject of eutectics is also fully discussed in Harker’s Natural history of igneous rocks, and Elsden’s Chemical geology. THE MOLTEN MAGMA. 303 tion. This is not far from the molecular ratio 3AlKSi 3 0 8 :5Si0 2 , although simple molecular ratios can not necessarily be assumed in eutectic mixtures. The latter, so far as present evidence goes, are not definite compounds. The water-salt eutectic is not a hydrate, but a mixture of salt and ice, which, however, happens to approximate rather closely in composition to NaCl+10H 2 O. In the first of the memoirs just cited, which is rich in data relative to the physical constants of molten rocks, minerals, and slags, Vogt attempts to fix the composition of a number of eutectic mixtures. Some of them are as follows, the figures referring to percentages: 68 diopside with 32 olivine. 74 melilite with 26 olivine. 65 melilite with 35 anorthite. 40 diopside with 60 akermanite. 74.25 anorthite with 25.75 quartz. 75 albite with 25 quartz. The last two ratios are practically identical with the orthoclase- quartz ratio as given above. It is, however, a grave question whether in a strict sense eutectics of feldspar and quartz are possible. Quartz is capable of formation only below 800°, and one modifica- tion of it only below 575°. In the pegmatites of Maine, as described by E. S. Bastin, 1 the quartz is often of the low temperature variety, and crystallization was further modified by the presence of gaseous or vaporous constituents in the magma. Fluid inclusions are also common in the quartz. The solidification of these pegmatites was therefore a complex process, and by no means so simple as the theory of eutectics would seem to demand. A feldspar-silica eutectic, on the other hand, in which during prolonged cooling a gradual develop- ment of the silica as quartz occurred may be conceivable. 2 The entire subject of eutectics, in reference to rock formation, is elaborately discussed by Vogt, who considers them in connection with the melting points, and the specific and latent heats of the com- ponent minerals. These data, however, are more or less crude, and Vogt’s results are therefore to be regarded merely as first approxima- tions to the solution of the problems proposed, and as subject to very critical revision. Vogt also sought to determine the molecular weights of several silicates from the observed melting point depres- sions, and concluded that they were represented by their simplest empirical formulae. The fused minerals, as such, exist in the fluid magma, although they are partly subject to electrolytic dissociation. The latter phenomenon has also been much studied by Doelter. 3 The essential point in Vogt’s and also in Doelter’s work is that they 1 Jour. Geology, vol. 18, 1910, p. 297. Also, more in detail, in Bull. U. S. Geol. Survey No. 445 , 1911. 2 For the conditions under which quartz can form see the section on that min eral in the following chapter. » Monatsh. Chemie, vol. 28, 1907, p. 1313; Sitzungsb. Akad. Wien, vol. 117, 1908, pt. 1; Zeitschr. Elektro- chemie, 1908, p. 552. 304 THE DATA OF GEOCHEMISTRY. attempt to apply modern physicochemical methods to the investiga- tion of magmas, and whether their conclusions are maintained or not they are at least suggestive. Up to this point we have considered only simple cases to which the theory of eutectics is easily applied. In salt and water we have merely a system of two components, and the examples given by Vogt are of like simplicity. But igneous rocks are, as a rule, much more complex, and may contain from three to many component minerals- For conditions like these the theoretical treatment is as yet undevel. oped, although the researches of Van’t Hoff on the Stassfurt salts suggest, with their diagrams, certain analogies which may be followed in the future. The laws of equihbrium must apply to all possible cases of solution, even though we may be unable as yet to trace the details of their working. Just as the Stassfurt problem is complicated by the deposition of hydrates and double salts, so from the magma complex silicates can form, and the exact conditions under which each may develop are so far only partially determined. The diffi- culties that confront us here are well pointed out by Roozeboom 1 in his great work on the phase rule, where he calls attention to the fact that an igneous rock represents many components and many solid phases. Some of the latter are definite compounds, and some are mixed crystals from isomorphous series. If the cooling of the magma has been too rapid, supersaturation may have occurred, with a change in the order of deposition of the minerals and the formation of some undifferentiated glass base. Furthermore, lava rising from a great depth undergoes a change of pressure, which modifies the relative solubility of its components and alters the position of the eutectic point. SEPARATION OF MINERALS. It is evident, from what has been said, that no universal concrete rule can be laid down to determine the order in which the different minerals will separate from a cooling magma. The broad, general principles are clear enough, but their application to the problem under consideration is an affair of the future. For the present, therefore, we must depend upon accurate observations and experi- ments, and in that way accumulate data for theory to work upon. The much-cited phase rule, with its diagrams, gives us a mathe- matical method of dealing with our facts, but it is inoperative with- out them. When accurate numerical data have been obtained, then the rule will become applicable to the relatively simpler cases; but i H. W. Bakhuis Roozeboom, Die heterogenen Gleichgewichte vom Standpunkte der Phasenlehre, vol. 2, Braunschweig, 1904, pp. 240 et seq. For a simple application of a phase-rule diagram to a system of two components see W. Meyerhoffer, Zeitschr. Kryst. Min., vol. 36, 1902, p. 592. T. T. Read (Econ. Geology, vol. 1, 1905, p. 101) has discussed the application of the phase rule to the study of magmas, but his suggestions have been criticized by A. L. Day and E. S. Shepherd (idem, p. 286). C. Doelter (Min. pet. Mitt., vol. 25, 1907, p. 79) has studied what he calls the “stability fields” of certain minerals. THE MOLTEN MAGMA. 305 anything more complex than a four-component system is likely to be unmanageable. At present, however, we can see some of the con- ditions which are involved in the general problem. First, the entire composition of the magma must be taken into account, together with the pressure under which it solidifies. An ordinary lava, cooling on the surface of the earth, will behave very differently from similar material which solidifies at a great depth to form a laccolith or batholith. In the latter case its gaseous contents are not so completely lost, and they, especially the water vapor, play an important part in determining the order of mineral deposition. The retention, under pressure, of boric acid and fluorine will cause the formation of compounds which do not appear in surface eruptions, and such minerals as tourmaline and the micas become possible. If in any given case we regard the eutectic mixture as the solvent, the minerals that are in excess of its ratios will be the first to crystallize. Their order of deposition will , then depend upon three essential conditions — namely, their relative abundance , 1 their solu- bility in the eutectic, and their points of fusion. Other things being equal, the less soluble and less fusible substances will be formed earliest. With an excess of alumina, corundum and spinel may form, and as a general rule the so-called accessory minerals, the more trivial constituents of a rock, are among the first separations. Apatite, sulphides, and the titanium minerals belong in this class. Although the sulphides are more easily fusible than the silicates, their insolubility in a silicate magma causes their early precipitation. According to J. H. L. Vogt , 2 the sulphides are much more soluble in very hot magmas than they are at lower temperatures, and this order of difference is one which should be taken into account. Solu- bility varies with temperature, and differently with different sub- stances. It also varies with the solvent, and J. Morozewicz 3 has shown that alumosilicates rich in soda dissolve alumina much more freely than the corresponding potash compounds, in which it is little soluble, if at all. So also the sulphides, as Vogt has pointed out, are more soluble in femic magmas than in the salic varieties. They are consequently more abundant in basalts and diabases than they are in quartz porphyry or rhyolite. We have here, apparently, a case of limited miscibility between fused sulphides and fused silicates, while on the other hand the silicates themselves seem to be miscible in all proportions. At least, in the latter case, no limitation has 1 F. Loewinson-Lessing (Compt. rend. VII Cong. g4ol. intemat., 1897, pp. 352-353) has called attention to the fact that relative abundance is fundamentally important; that is, silica will divide itself among the several bases in accordance with the law of mass action; or, in other words, that law will determine what silicates can form. Its detailed application, however, is perhaps not practicable. 2 Die Silikatschmelzlosungen, pt. 1, 1903, pp. 96-101. 3 Min. pet. Mitt., vol. 18, 1888-89, pp. 56, 57. 97270°— Bull. 616—16 20 306 THE DATA OF GEOCHEMISTRY. been observed, except in so far as chemical reactivity renders the mutual presence of certain species impossible. In an actual magma these incompatibilities do not exist, nor do they become evident when we fuse together several oxides to form an artificial melt. When, however, we fuse mixtures of minerals, as in the researches of J. Lenarcic, 1 M. Vucnik, 2 and B. Yukits 3 the limitations of this class become evident. For instance, when magnetite is fused with labra- dorite it is absorbed, and upon cooling the melt, augite crystals appear. With magnetite and anorthite, hercynite may be formed; leucite and acmite give magnetite, leucite, and glass; and so on. Again, leucite and nephelite are incompatible with quartz, which converts them into feldspars; and a multitude of such conditions help to determine what compounds shall crystallize from any given magma. In a magma of defined composition certain compounds are capable of formation, others are not; and these limitations are imperative. In the next chapter, upon rock-forming minerals, they will be considered more in detail. In ordinary solutions two substances having an ion in common diminish the solubility of each other. How far this rule may apply to magmas is uncertain, and especially so because of our ignorance as to what the ions actually are. 4 Still we may assume that olivine, Mg 2 Si0 4 , and enstatite, MgSiO s , have magnesium ions in common,, and with them the rule ought to work. 5 Each should be less soluble in presence of the other than it is when present alone, and the same condition ought to hold for the two potassium salts leucite and ortho- clase, or the sodium couple albite and nepheline. With mixtures of several possible silicates the rule is more difficult to apply, for then complex ions are likely to form. For instance, in a magma capable of yielding olivine, enstatite, albite, and anorthite the ions may be Mg, Ca, Na, Si0 3 , Si0 4 , AlSi0 4 , and AlSi 3 0 8 . Even in such a case, which is purely hypothetical, two of the supposed minerals have an ion in common, and olivine and enstatite should be the first to sepa- rate. Here we have a suggestion of what really happens in a vast number of cases, possibly in a large majority of cooling magmas. The order in which the minerals are deposited is essentially that 1 Centralbl. Min., Geol. u. Pal., 1903, pp. 705, 743. 2 Idem, 1904, pp. 295, 340, 364; 1906, p. 132. 3 Idem, 1904, pp. 705, 739. See also memoirs by B. K. Schmutz, Neues Jahrb., 1897, Band 2, p. 124; K. Bauer, idem, Beil. Band 12, p. 535, 1899; K. Petrasch, idem, Beil. Band 17, p. 498, 1903; H. H. Reiter, idem, Beil. Band 22, p. 183, 1906; R. Freis, idem, Beil. Band 23, p. 43, 1907; V. Poschl, Centralbl. Min., Geol. u. Pal., 1906, p. 571; Min. pet. Mitt., vol. 26, 1908, p. 412; H. Schleimer, Neues Jahrb., 1908, Band 2,p. 1; M.Urbas, idem, Beil. Band, vol. 25, 1908, p. 261; M. Hauke, idem, 1910, p. 1; Vera Hammerle, idem, Beil. Band, vol. 29, 1910, p. 719; and H. Andesner, idem, Beil. Band, vol. 30, 1910, p. 467. 4 For a discussion of this subject in greater detail see J. H. L. Vogt, Min. pet. Mitt., vol. 27, 1908, p. 133. 6 This example is perhaps not perfect, for N. L. Bowen (Am. Jour. Sci., 4th ser., vol. 37, 1914, p. 487) has shown that enstatite on fusion breaks up into forsterite and free silica. Still, it serves to illustrate the principle. THE MOLTEN MAGMA. 307 laid down by H. Rosenbusch , 1 namely, ores and oxides first, then the ferromagnesian minerals, then the feldspars, and finally, if an excess of silica is present, quartz. The rule, however, is not and can not be universal, and to it there are many exceptions. Its common validity must be ascribed to the fact that most igneous rocks are formed from relatively few components, with a correspondingly mod- erate number of possibihties. So far as they are of the same general nature they consolidate most commonly in the same general way. To a limited degree minerals are deposited from a magma in the reverse order of their fusibility, the more infusible first; but the rule, as we have seen, is by no means general. In certain cases, however, it holds, especially in the formation of the successive members of an isomorphous series. Plagioclase feldspars, for example, often exhibit a zonal structure, with the less fusible lime salts concentrated at the crystalline centers, and the more fusible soda salts proportionally more abundant around their outer surfaces. The order of fusibility seems to be rather a minor factor in the process of mineral formation during magmatic cooling. The early crystallization of leucite and olivine may be due either to their relative infusibility, to their insolu- bdity in the remainder of the magma, or, as Doelter 2 supposes, to their superior stability at high temperatures. Viscosity, supersatu- ration, undercooling, and rate of cooling all play their respective parts in the solidification of a magma, and the interpretation of the evidence in any particular instance is not a simple matter . 3 DIFFERENTIATION. The question whether there is, within the earth, a single, sensibly homogeneous magma is one that concerns geology but does not seem to be directly approachable through chemical evidence. If, however, we consider the problem locally with reference to effusions from one definite volcanic center, the chemist may have something to say. Even here the discussion must be mainly physical, but chem- ical principles are also involved in its settlement, for the reason that chemical differences characterize the lavas, and they demand con- sideration. 1 Neues Jahrb.,1882, Band 2, p. 1. Compare papers by J. Joly, Proc. Roy. Soc. Dublin, vol. 9, 1900, p. 298; J. A. Cunningham, idem, 1901, p. 383; and W. J. Sollas, Geol. Mag., 1900, p. 295. On the order of con- solidation of magmatic minerals there is a copious literature. 2 Sitzungsb. K. Akad. Wiss. Wien, vol. 113, 1904, p. 495. Doelter gives many data on the separation of minerals during the cooling of melts of known composition. The different species were first fused together. 3 The importance of discriminating between the fusibility of a mineral and its solubility in a magma is strongly emphasized by A. Lagorio, in Zeitschr. Kryst. Min., vol. 24, 1895, p. 285. Minerals may dis- solve at temperatures far below their melting points, just as salt dissolves in water. It is also necessary to distinguish between simple solution and chemical reactivity. In the one process a body dissolves and recrystallizes from solution without change. In the other it dissolves because of reactions with the solvent, and new compounds are generated. In either process, however, a solution may become saturated, and then its solvent action ceases. On viscosity as related to chemical composition in silicate fusions see E. Greiner, Inaug. Diss., Jena, 1907. 308 THE DATA OF GEOCHEMISTRY. It is now a commonplace of petrology that within a given area there may be a variety of igneous rocks exhibiting a relationship to one another and indicating, by their mode of occurrence, that they had a common origin. To what is this “ consanguinity/ ’ as Iddings calls it, due ? If the lavas, which may differ widely, came from one and the same fissure or crater, how were their differences brought about ? To this question there have been many answers, hut its dis- cussion still continues voluminously, and the last word is not yet said. If distinct magmas exist, which are ejected sometimes sepa- rately and sometimes commingling, the problem becomes apparently simple, and this method of solution has been repeatedly proposed. Bunsen assumed the existence of two such magmas, the normal pyroxenic and the normal trachytic, and Durocher has put forth similar views. Other petrologists have thought that there are more than two fundamental magmas, but such a multiplication of assump- tions can only end in confusion. The conception is simple enough, but its application to observed phenomena is quite the reverse. With this phase of the question chemistry has little to do. The prevalent modern opinion favors the idea that at each specified locality there is one essentially homogeneous magma, from which, by some process of differentiation, the various rock species of the region have been derived. Under what conditions and by what processes can such a differentiation be produced? Upon this problem, presented in this form, physical chemistry has some suggestions to offer, regardless of the antecedent assumptions or of the geological evidence upon which it is based. 1 It is not necessary for us now to consider the historical aspect of the discussion, for that has been well done by several other writers. J. P. Iddings, especially, in his memoir upon the origin of igneous rocks, 2 and more recently W. C. Brogger 3 and F. Loewinson-Less- ing 4 have done full justice to this side of the question. We need only take up broadly the hypotheses which have been suggested in order to explain the observed differentiation and examine them as to their validity. An exhaustive discussion of details is out of the question. Although R. W. Bunsen was the first to show that a magma is really a solution, little attention was paid to this consideration until A. La- gorio, 5 in 1887, published his famous memoir on the nature of the 1 Harker, in his Natural history of igneous rocks, devotes a chapter to '‘hybridism” — that is, to rocks formed by the commingling of magmas. Another chapter is given to the question of differentiation. Elsden, in his Chemical geology, also discusses the general problem at some length. 2 Bull. Philos. Soc. Washington, vol. 12, 1892, p. 89. 3 Die Eruptivgesteine des Kristianiagebietes, pt. 3, 1898, pp. 276 et seq. 4 Compt. rend. VII Cong. geol. internat., 1897, p. 308. 6 Min. pet. Mitt., vol. 8, 1887, p. 421. This memoir is rich in references to former literature. THE MOLTEN MAGMA. 309 u glass base” or groundmass. In developing his fundamental con- ception Lagorio called attention to “Soret’s principle,” which asserts that when two parts of the same solution are at different temperatures there will be a concentration of the dissolved substance in the cooler portion. Through the operation of this process, namely, unequal cooling, it was thought that a homogeneous molten mass might be- come heterogeneous, the substances with which a magma was most nearly saturated tending to accumulate at the cooler points, leaving the warmer portions with an excess of the solvent material. This view was speedily adopted by many petrographers, but objections to it were soon found, and it is now generally abandoned. G. F. Becker 1 showed that to produce the observed phenomenon in so viscous a medium as molten lava by such a process of molecular diffusion would require almost unlimited time; and H. Backstrom 2 pointed out that although the operation of Soret’s principle might cause changes in the absolute concentration, it could no more alter the relative proportions of the dissolved substances than it could in a mixture of gases. Another process which surely plays some part, great or small, in the differentiation of magmas is the solution of foreign material. The molten lava, as it rises from the depths to the surface of the earth, is inclosed between walls of rock upon which it exerts a solvent action. This action may be very slight or it may be important; and its extent will depend on the character of the magma, the character of the rock with which it is in contact, the temperature, and the pressure. Not one of these factors can be set aside as negligible. The absorbed rock may be either igneous or sedimentary ; the effect produced upon it may be limited to a thin contact zone or it may permeate large masses of material; and no general rule governs the process entirely. The wall rock varies in solubility with respect to the magma, and this condition, modified as it must be by variations in temperature, is of prime importance. If a magma is saturated with respect to the substances contained in its walls, its solvent action will be slight; if unsaturated, its activity must be greater. A basaltic magma should take up silica ; a siliceous magma might absorb bases. For example, blocks of limestone, more or less altered by contact with the molten magma, are ejected from some volcanoes, and may be found embedded in the solidified lavas. In extreme cases they may disappear en- tirely, leaving a local enrichment in lime salts as evidence of their 1 Am. Jour. Sci., 4th ser., vol. 3, 1897, p. 21. 2 Jour. Geology, vol. 1, 1893, p. 773. See also F. Loewinson-Lessing, Compt. rend. VII Cong. g<5ol. internat., 1897, p. 390. 310 THE DATA OF GEOCHEMISTRY. former nature . 1 This general process, this assimilation of extraneous material, is given much weight by Johnston-Lavis and Loewinson- Lessing in their discussions of magmatic differentiation; but its effectiveness is by no means universally admitted. R. A. Daly , 2 a recent advocate of the assimilation theory, has sought to explain the mechanism of igneous intrusions by a process which he calls “ mag- matic stoping.” He supposes that a batholithic magma eats its way up by solvent action on the invaded rocks. Blocks of the latter, loosened by this process, sink into the fluid mass and are gradually dissolved. Thus the composition of the magma is altered. Daly also argues in favor of the view that such a magma, by “gravitative adjustment,” will separate into layers, the denser submagma below, the lighter above. The latter conception is not new, and has had many supporters. The hypothesis advanced by A. Michel-Levy 3 that differentiation is brought about chiefly by a circulation at high temperatures and under great pressures of the so-called “fluides mineralisateurs ” — that is, of water and the other vapors or gaseous contents of the magma — is one which deserves serious consideration. These agents are sup- posed to entangle certain other constituents, the lighter substances of the magma, and to concentrate them in the upper layers of the fused mass. Silica and the feldspathic minerals would thus accumulate near the top of a volcanic reservoir, leaving the ferromagnesian miner- als in greater proportion at the bottom — an order corresponding with a common order of ejectment during eruptions. This order, how- ever, is not invariable, and in Great Britain, according to A. Geikie , 4 it was generally reversed. There the femic rocks represent the earli- est outflows and the salic rocks came later. A progressive enrich- ment in silica took place, instead of the impoverishment that Michel- Levy’s process would imply. In the Yellowstone Park, according to 1 See, for example, H. J. Johnston-Lavis, The ejected blocks of Monte Somma: Trans. Edinburgh Geol. Soc., vol. 6, 1892-93, p. 314. Also a paper in Natural Science, vol. 4, 1894, p. 134. F. Loewinson-Lessing (loc. cit.) gives many other references to literature on this subject. For experimental data on the solu- bility of corundum, emery, andalusite, kyanite, kaolin, pyrophyllite, leucite, and quartz in magmas, see A. Lagorio (Zeitschr. Kryst. Min., vol. 24, 1895, p. 285); also C. Doelter and E. Hussak (Neues Jahrb., 1884, Band 1, p. 18), who operated on olivine, pyroxene, hornblende, biotite, feldspars, quartz, garnet, iolite, and zircon in much the same way. How far these experiments, conducted on small samples during short times, can be used to illustrate natural phenomena is doubtful, but they do give some information of value. On the absorption of limestone by granite see A. Lacroix, Compt. Rend., vol. 123, 1896, p. 1021. 2 Am. Jour. Sci., 4th ser., vol. 15, 1903, p. 269; vol. 16, 1903, p. 107; vol. 20, 1905, p. 185; vol. 26, 1908, p. 17, and in the Rosenbusch “Festschrift,” 1906, p. 203. See also Bull. U. S. Geol. Survey No. 209, 1903, p. 104, on the rocks of Mount Ascutney. A discussion of Daly’s views, mainly adverse, at a meeting of the Geo- logical Society of Washington, is reported in Science, vol. 25, 1907, p. 621. J. H. L. Vogt (Die Silikatschmelz- losungen, pt. 2, 1904, p. 225) regards the assimilation theory as quite untenable. Daly’s views have been accepted by J. Barrell, Prof. Paper U. S. Geol. Survey No. 57, 1907, pp. 155-156; E. C. Andrews, Rec. Geol. Survey New South Wales, vol. 8, 1905, p. 126; and A. P. Coleman, Jour. Geology, vol. 15, 1907, p. 773, On magmatic assimilation in the Adirondacks see W. J. Miller, Bull. Geol. Soc. America, vol. 25, p. 243, 1914. 3 Bull. Soc. g<§ol. France, 3d ser., vol. 25, 1897, p. 367. 4 The ancient volcanoes of Great Britain, vol. 2, 1897, p. 477. THE MOLTEN MAGMA. 311 J. P. Iddings , 1 lavas of medium composition were emitted first, and the differentiation was a splitting up of the magma into femic and salic portions. The sequence of lavas, then, appears to have been different in different regions, and the irregularities remain to be explained. Apart from this digression, however, the suggestions of Michel-Levy should be borne in mind. The magmatic vapors must exert an important influence upon the process of differentiation, for they tend to accumulate in the upper part of a lava column or reser- voir and to modify its properties locally. It is quite possible that they may bring to the top some of the more easily sublimable oxides or silicates, together with decomposable fluorides and chlorides, and during an eruption these substances would be ejected first. A com- plete segregation, however, is not assumed — only a differential con- centration of the magmatic components. It is obvious that a more important function of the tl mineralizers ” is to increase the fusi- bility of the magmatic mass and to diminish its viscosity, thereby facilitating crystallization. In a later paper than the one previously cited G. F. Becker 2 has shown that fractional crystallization may have been an important factor in producing differentiation. This is a process which is well un- derstood, and it must have been more or less operative. From this point of view magmatic differentiation becomes a part of the general cooling process, and not a phenomenon to be considered aside from the ordinary solidification of a lava. The magma, whether it is forming a dike or a laccolith, is inclosed between walls which are cooler than itself, and along these surfaces the less fusible or less soluble minerals will first crystallize. The process is aided by the circulation of con- vection currents; and that portion of the fused mass which last solidifies, the mother liquor, will be the portion of maximum fusibility, and, therefore, approximate to a eutectic mixture. The center of the dike or laccolith will thus have one composition and its outer parts another. In his memoir upon the Highwood Mountains L. V. Pirsson 3 discusses the process in some detail and shows how convec- tion and crystallization may go on together. When great differences in specific gravity exist, as in the separation of the heavy titaniferous magnetite of the Adirondacks from the lighter rocks of the same magmatic mass , 4 the crystallizing substances may settle to the bot- tom and form a distinct layer quite unlike the superincumbent material. Even very moderate differences of density may produce 1 Bull. Philos. Soc. Washington, vol. 12, 1892, p. 89. Compare J. E. Spurr, Jour. Geology, vol. 8, 1900, p. 621, on the succession of the igneous rocks in the Great Basin of Nevada. Spurr gives a good historical summary of the subject, beginning with the pioneer work of Richthofen. 2 Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 257. 3 Bull. U. S. Geol. Survey No. 237, 1905, p. 183. Compare also A. Harker, Quart. Jour. Geol. Soc., vol. 50, 1894, p. 324, and T. L. Walker, Am. Jour. Sci., 4th ser., vol. 6, 1898, p. 410. 4 See J. F. Kemp, Nineteenth Ann. Rept. U. S. Geol. Survey, pi. 3, 1899, p. 417. 312 THE DATA OF GEOCHEMISTRY. similar results, although in less degree. For example, Loewinson- Lessing 1 has shown that in certain Vesuvian lavas leucite crystals have risen to the top, while augite sank to the bottom . 2 In the differ- entiation of the eruptive iron ores of Norway, as described by J. H. L. Vogt , 3 the same process may operate, although Vogt gave another interpretation to the phenomena. In cases of this kind the liquation hypothesis of J. Durocher 4 may be partly applicable, and we can easily conceive of the cooling magma as separating into lighter and heavier layers, even before solidification begins. Kemp, in the paper just cited, remarks that copper matte settles out almost completely from a viscous mixture of matte and slag, although in a large mass of magma convection currents might hinder the perfect working of such a process. Liquation, then, must be regarded as a possible mode of differentiation, but probable only in certain special cases. It implies a limited miscibility of the magmatic solutions, and that does not often occur. J. Morozewicz , 5 however, in his experiments upon artificial magmas observed several cases in which his melts differed in com- position from top to bottom, the undermost portion being the heav- iest. Similar differences of density are well known to the glass makers, as shown by variations in refractive capacity between the top and bottom portions of their melts. Such a “gravitative adjust- ment” is presumably most effective in slowly cooling magmas, especially when partial crystallization has occurred. The minerals first formed must have time to sink. The rate of cooling, therefore, is a distinct factor in the differentiation of igneous rocks. To these agencies in the process of differentiation must be added that of pressure. This has been taken into account by Martin Schweig , 6 whose views may be briefly summarized or paraphrased as follows: In a molten magma, under great pressure, partial crystal- lization occurs ; the crystals formed sink within the fluid mass, while their mother liquor accumulates above them. An eruption takes place, the mother liquor is ejected, and with the consequent relief of pressure the fusibility of the separated crystalline matter is increased. The latter, remelted, is expelled by a later explosion, and in this way the magma, originally homogeneous, gives rise to two or more differ- ent lavas emitted from the same vent. The separation is effected in the first place by fractional crystallization, aided by gravity; and then, under reduced pressure, the crystalline layer again liquefies. 1 Studien ueber die Eruptivgesteine, St. Petersburg, 1899, p. 155. 2 Similar observations are recorded by much earlier workers, as, for instance, Charles Darwin, in Geo- logical observations on volcanic islands, 1844, p. 117, and P. Scrope in his treatise Volcanos, 1872, p. 125. 3 See summary by J. J. H. Teall in Geol. Mag., 1892, p. 82. 4 Annales des mines, 5th ser., vol. 11, 1857, p. 217. 3 Min. pet. Mitt., vol. 18, 1888-89, p. 233. N. L. Bowen (Am. Jour. Sci., 4th ser., vol. 39, 1915, p. 175), in some experiments upon the magnesian silicates, has found that in a melt olivine and pyroxene crystallize out and sink, while tridymite floats. 6 Neues Jahrb., Beil. Band, vol. 17, 1903, p. 516. Originally published as a doctoral dissertation. The paper contains a good summary down to 1903 of the entire subject of differentiation. THE MOLTEN MAGMA. 313 This is a plausible hypothesis, but it leaves some things out of account. Pressure, in the first instance, raises the melting points of the fused minerals, but the water and gases dissolved in the magma act in the opposite way. They tend to make the magma more fusible. When, by eruption, these gases escape, there will be a decrease of fusi- bility to offset the gain from reduced pressure, and what the alge- braic sum of this gain and loss may be no man can say. The oppos- ing tendencies may balance, but it is more probable that one or the other will be the stronger, and beyond this point, with the available evidence, our reasoning can not go. During an eruption the com- position of a magma, its gaseous load, its temperature, and the pres- sure on it are all varying; some of the variations are slow and gradual, others are rapid; heat may be lost by cooling 1 or evolved by chemical change; and no equation can yet be written in which each of these factors shall receive its proper valuation. After eruption the phenomena are less complex; but even then we are only able to follow them partially. Fractional crystallization, liquation, the in- fluence of dissolved vapors, and the assimilation of foreign material are all intelligible processes, but the first one named is the most general and presumably the most important of all. Even its influ- ence is variable, however, becoming zero in eutectic mixtures and increasing in potency as we recede from the eutectic point. The more closely the composition of a magma approaches eutectic ratios the less capable of fractionation it becomes. RADIOACTIVITY. This chapter would be incomplete without some reference to recent speculations and investigations relative to the sources of volcanic heat. That heat hitherto has been commonly referred either to the molten matter left over after the consolidation of the lithosphere or to a generation from mechanical sources, such as pressure and the friction due to movements within the crust. The discovery of radium, however, which emits heat continuously, has led to new con- ceptions that are at least worth mentioning . 2 The quantity of heat emitted by radium has been measured by sev- eral investigators. The subjoined table gives most of the results obtained, expressed in gram calories per gram of pure radium per hour : 1 The sudden expansion of the gases released at the beginning of a volcanic eruption must exert a note- worthy cooling effect on the residual magma. 2 A discussion of the purely physical or mechanical sources of heat does not fall within the scope of this treatise. 314 THE DATA OF GEOCHEMISTRY. Heat emitted by radium. Authority. Reference. Small calories. P. Curie and A. Laborde Compt. Rend., vol. 136, 1903, p. 673. 100 approx. E. Rutherford and II. T. Barnes. Philos. Mag., 6th ser., vol. 7, 1904, p. 202. 100 approx. C. Runge and J. Precht Jour. Chem. Soc., vol. 86 (2), 1904, p. 7. 105. F. Paschen Physikal. Zeitschr., vol. 5, 1904, p. 563. 126. J. Precht Annalen der Physik, 4th ser., vol. 21, 1906, p. 595. 134.4. E. v. Schweidler and V. F. Hess. Monatsh. Chemie, vol. 29, 1908, p. 853. 118. W. Duane Compt. Rend., vol. 148, 1909, p. 1448. 120. W. Duane Am. Jour. Sci., 4th ser., vol. 31, 1911, p. 247. 104 to 117. H. Pettersson Chem. Abstracts, vol. 5, p. 2365, 1911. 116.4. The differences between these determinations are due partly to differences in the atomic weight assigned to radium and partly to different methods of measurement; but they are immaterial in respect to the present discussion. It is enough to note that 1 gram of radium spontaneously emits heat enough every hour to raise the temperature of more than 100 grams of water 1° Centigrade, 1 an enormous quantity in comparison with the energy displayed in even the most violent chemical reactions. How large a part does this evolution of heat play in volcanic phenomena or in maintaining the temperature of the earth ? The principal radioactive elements, so far as present knowledge goes, are uranium, radium, and thorium. Actinium, ionium, and polonium are also known, but their thermal efficiency is yet to be determined. Potassium and rubidium are feebly radioactive. Ra- dium, which is a derivative of uranium, is by far the most important radioactive element so far discovered, and for immediate purposes is the only one which need be taken into account. It has been sug- gested that the atomic degradation which characterizes the elements above named is probably a general property of all matter, but that is, as yet, only an unproved speculation. 2 It may or may not be sustained by future investigators. The materials forming the crust of the earth, whether igneous or sedimentary, are now known to be measurably radioactive. This 1 The most probable value is 118 cal. 2 N. R. Campbell (Philos. Mag., 6th ser.,vol. 9, 1905, p. 531; vol. 11, 1906, p. 206) claims to have discov- ered radioactivity in several common metals. H. Greinacher (Annalen der Physik, 4th ser., vol. 24, 1907, p. 79) attempted to determine the radioactivity of common substances by a calorimetric method, and obtained negative results. If it exists, its intensity is too small to be measured by any known method. See also W. W. Strong, Am. Chem. Jour., vol. 42, 1909, p. 147; M. Levin and R. Ruer, Physikal. Zeitschr., vol. 10, 1909, p. 576. THE MOLTEN MAGMA. 315 radioactivity is even communicated to the waters 1 and the atmos- phere, but is most marked in the older rocks, and it is mainly attrib- uted to the widespread diffusion of radium in exceedingly minute traces. The other unstable elements, doubtless, play their part, but radium appears to be the principal agent in producing the phenom- enon. The measurements of what may be called geochemical radio- activity are therefore commonly stated in terms of radium. The decay of radium is through a series of stages in which a num- ber of products are successively formed. The first of these products, the radium emanation, to which the name niton has recently been given, is a gas belonging to the helium-argon group. By decompos- ing a rock and bringing it into solution this gaseous, radioactive substance can be isolated, and its amount determined by its action upon the air within an electroscope. The details of the operation need not be considered here. They are given by Strutt in his papers upon radium in rocks, and are also summed up by Joly in his treatise upon Radioactivity and Geology. The amount of emanation is strictly proportional to the amount of radium from which it was generated, provided enough time is allowed for it to accumulate until its rate of production and rate of decay are in exact equilibrium. These rates are known to a fair degree of approximation, and hence measurements of the emanation are easily restated in equivalent quantities of radium. Since 1906 numerous determinations of radium in rocks have been made, especially by R. J. Strutt and J. Joly. 2 From Strutt’s meas- urements, as corrected by Eve and McIntosh, the radium in 28 igneous rocks ranges from 0.30 X 10 -12 to 4.78 X 10 -12 grams per gram of mate- rial. The average is 1.7 XlO -12 . The highest values were obtained from granites, the lowest from basalts and olivine rocks. For sedi- mentary rocks the average of 17 determinations gave 1.1 XlO -12 1 The radioactivity of many spring waters has already been noted in the chapter on mineral springs. According to J. Joly (Radioactivity and geology, p. 48), sea water is radioactive to an extent equivalent to an oceanic content of 20,000 tons of radium. The deep-sea sediments are much more radioactive. A. S. Eve, however (Philos. Mag., 6th ser., vol. 18, 1909, p. 102), found much smaller amounts of radium in sea water than Joly— in fact, only about one-seventeenth as much. For a reply by Joly see the same volume, p. 396. F. Himstedt (Physikal. Zeitschr., vol. 5, 1904, p. 210) attributes the radioactivity of thermal waters to deep-seated radioactive minerals. 2 See Radioactivity and geology, already cited. For Strutt’s papers see Proc. Roy. Soc., ser. A, vol. 77, 1906, p. 472; vol. 78, 1906, p. 150; vol. 80, 1908, p. 572; vol. 84, 1910, p. 377. The figures given by Strutt in the first of these papers involved an erroneous constant and were corrected by A. S. Eve and D. McIntosh, Philos. Mag., 6th ser., vol. 14, 1907, p. 231. These authors also measured the radioactivity of various rocks near; Montreal. See also memoirs by C. C. Farr and D. C. H. Florance, Philos. Mag., 6th ser., vol. 18, 1909, p. 812 A. L. Fletcher, idem, vol. 20, 1910, p. 36; vol. 21, 1911, pp. 102, 770; vol. 23, 1912, p. 279; A. Gockel, Jour. Chem. Soc., vol. 100, pt. 2, 1911, p. 174, abstract; E. H. Buchner, idem, p. 243, abstract; and vol. 102, pt. 2, 1912, p. 525, abstract. Recent papers by Joly, partly upon radium and partly upon thorium, are in Philos. Mag., 6th ser., vol. 17, 1909, p. 760; vol. 18, 1909, pp. 140, 577; vol. 20, 1910, pp. 125, 353; vol. 23, 1912, p. 201; vol. 24, 1912, p. 694. On the radioactivity of pitchblende see H. H. Poole, idem, vol. 19, 1910, p. 314. On Australian minerals, D. Mawson and T. H. Laby, Chem. News, vol. 92, 1905, p.39. On lavas, O. Scarpa, Atti R. accad. Lincei, 5th ser., vol. 16, 1907, p. 44; R. Nasini and M. G. Levi, idem, vol. 15, 1906, p. 391; vol. 17, p. 432; and G. T. Castorina, Neues Jahrb., 1907, p. 11 (abstract). J. W. Waters (Philos. Mag., 6th ser., vol. 19, 1910, p. 903) has studied the presence of radioactive minerals in common rocks. On radiothorium see G. A. Blanc, idem, vol. 13, 1907, p. 378; vol. 18, 1909, p. 146. 316 THE DATA OF GEOCHEMISTRY. grams per gram, the mean of the two averages being 1.4 XlO -12 . This amount is equivalent to an emission of heat, the heat given out by radium, about 28 times as great as is needed to account for the observed temperature gradient within the crust of the earth. Joly’s figures are much higher than those of Strutt, and cover a much larger number of determinations. As summed up by him, 1 the mean radium content of igneous rocks is 5.5 XlO -12 grams per gram, and that of sedimentary rocks 4.3 XlO -12 . Joly, moreover, finds only slight differences (as compared with Strutt’s results) between the plutonic rocks and those of volcanic origin. The dis- cordance between Strutt and Joly I cannot attempt to explain; but it seems probable that the granitic rocks and perhaps also the nephe- line syenites should show the highest values. In them the minerals of uranium, radium, and thorium are principally concentrated. 2 The radioactivity of the sedimentary rocks may be due to a distri- bution of the radium emanation by circulating waters, in which the gas is soluble. That of mineral springs is explicable in the same way. An attempt to compute the total amount of radioactive matter in the earth and its thermal significance would be obviously premature. The available data are too scanty, too discordant, and in some respects too incomplete for such a purpose. According to Strutt, the radium must be mainly within an outer shell of rock of relatively moderate thickness; for if it were uniformly diffused throughout the earth the earth would be growing warmer, which is highly improb- able. 3 Its precise distribution, however, can only be determined after many more experiments have been made, in which the radio- activity of each rock mass shall be correlated with its exact petrologic nature. An apparent “granite,” for example, may be really a meta- morphic rock in masquerade, and not a true plutonic. The thorough geologic and petrologic study of each sample of rock should go hand in hand with its radioactive measurement. 4 On the purely qualitative side of the problem more can be said. It is proved that the surface rocks of the earth contain diffused ra- dium, and that must be emitting heat at a definite rate. On this basis of fact Maj. C. E. Dutton 5 6 has suggested that volcanic heat may be developed by radioactivity in limited tracts from 1 to 3 and not over 4 miles below the surface of the earth. Heat thus developed might so accumulate as to fuse the rocks in which it was generated. In time, when enough material was melted, the water inclosed in the 1 Radioactivity and geology, p. 275. 2 G. von dem Borne (Zeitschr. Deutsch. geol. Gesell., vol. 58, 1906, p. 1) has found the granite of the Erzgebirge to be.strongly radioactive. 3 See also C. Liebenow, Physikal. Zeitschr., vol. 5, 1904, p. 625. * See A. Holmes (Sci. Progress, vol. 9, p. 12, 1914), for an interesting paper on the distribution of radium in the earth. 6 Jour. Geology, vol. 14, 1906, p. 259. THE MOLTEN MAGMA. 317 magma thus produced would become explosive, and an eruption would follow. Then a period of quiet would ensue, more heat would be released by the subterranean radium, and another explosion would occur. Thus Dutton explains the periodicity of eruptions, and he argues that no permanent reservoirs of molten magma are required in order to account for volcanic phenomena. Dutton’s views have been opposed by G. D. Louderback , 1 partly on geologic grounds, and partly because radiferous minerals, such as uraninite, are not found among volcanic products. On the other hand Joly 2 is inclined to favor Dutton’s suggestion, having found Vesuvian lavas to be highly radioactive. His figures, for the lavas emitted since 1621, give, in mean, 12.3 X 10~ 12 grams of radium per gram of rock, an astonishingly high figure, which seems to need verification. In speculations of this order there is a certain fascination, but also a tendency to push the conclusions too far. It is extremely proba- ble that radioaction may account for part of the heat emitted from volcanic vents, but whether it is the greater part or not is more uncer- tain. In any case, the reported radioactivity of potassium 3 must be taken into account, a metal millions of times more abundant than radium, which fact may offset its feeble intensity. Mechanical agen- cies and chemical reactions also count for something in volcanic phenomena, and the heat due to them should not be ignored. It is much more likely that the phenomena are produced by a combination of causes, than that they are ascribable to any one cause alone. The final degradation products of radium, and therefore of its parent, uranium, are helium 4 and probably lead. The elementary pedigrees are somewhat long, and their consideration in detail would be out of place here. The rate at which helium is generated is fairly well known, and upon that constant a method of determining the age of minerals has been based . 5 Given the amount of uranium or radium in a rock or mineral, and also the amount of helium which it contains, and the length of time required to generate the helium is easily calculated. 1 Jour. Geology, vol. 14, 1906, p. 747. 2 Philos. Mag., 6th ser., vol. 18, 1909, p. 577. The possible relation of volcanism to radioactivity is also discussed by F. von Wolff, Zeitschr. Deutsch. geol. Gesell., vol. 60, 1908, p. 431. 3 See N. R. Campbell and A. Wood, Proc. Cambridge Philos. Soc., vol. 14, 1906-1908, p. 15; and Campbell, idem, pp. 211, 557. Also E. Henriot, Compt. Rend., vol. 148, 1909, p. 910; Henriot and G. Varon, idem, vol. 149, p. 30; J. C. McLennan and W. T. Kennedy, Physikal. Zeitschr., vol. 9, 1908, p. 510. M. Levin and R. Ruer (idem, vol. 10, 1909, p. 576) studied many elements other than those strongly radioactive and found only K and Rb to emit undoubted radiations. W. W. Strong (Am. Chem. Jour., vol. 42, 1909, p. 147) obtained similar results and also found radioactivity in erbium. R. J. Strutt (Proc. Roy. Soc., vol. 81A, 1908, p. 278) suggests that the helium in the Stassfurt salts may be derived from potassium. * According to F. Soddy (Philos. Mag., 6th ser., vol. 16, 1908, p. 513) uranium and thorium both yieldhelium. 5 See E. Rutherford, Radioactive transformations, p. 187. For applications of the method, see R. J. Strutt, Proc. Roy. Soc., ser. A, vol. 81, 1908, p. 272; vol. 83, 1909, pp. 96, 298; vol. 84, 1910, pp. 194, 379. For criticisms of the method, see M. Levin, Zeitschr. Elektrochemie, vol. 13, 1907, p. 390; G. F. Becker, Bull. Geol. Soc. America, vol. 19, 1908, p. 113; J. Joly, Radioactivity and geology, ch. 11; J. Koenigsberger, Geol. Rundschau, vol. 1, 1910, p. 245; and A. Holmes, Proc. Roy. Soc., vol. 85A, 1911, p. 248. Holmes’s book, The age of the earth, London, 1913, is an excellent summary of the subject. See also recent papers by Joly in Philos. Mag., 6th ser., vol. 22, 1911, p. 358, and Sci. Progress, vol. 9, 1914, p. 37 318 THE DATA OF GEOCHEMISTRY. By this method Rutherford computed the ages of a fergusonite and a uraninite at something over 500,000,000 years; the figures being minima because some helium might have escaped. Joly, revising the calculations by means of a different value for the rate of change of uranium into radium, reduced the estimate to 241,000,000 years. By the same method Strutt found the age of thorianite from Ceylon to be above 280,000,000 years, and of a Canadian sphene 710,000,000 years. For more modern minerals Strutt found much smaller ages. Sphaerosiderite from the Oligocene was found to be 8,400,000 years old; hematite from the Eocene 31,000,000; and hematite from the Carboniferous 150,000,000 years. He also studied a number of phosphatic nodules, which gave still lower figures, in one case 225,000 ye’ars. The order of the geological formations was approximately followed, the oldest minerals being found in the oldest rocks. Assuming that lead is the final product of the degradation of uranium, B. B. Boltwood 1 has sought to determine the age of cer- tain minerals from the ratio between the two metals when both are present. The ratio multiplied by 10 10 gives the approximate age. By this method Boltwood found ages for various minerals, ranging between 410,000,000 years for a uraninite from Connecticut to 2,200,000,000 years for Ceylonese thorianite, the last figure being several times larger than that given by Strutt. The great uncertainty of such calculations, however, has been clearly pointed out by G. F. Becker, 2 who has applied it to the rare-earth minerals from Baringer Hill, Llano County, Texas, with the following results : Yttrialite (Mackintosh) 11,470,000,000 years. Yttrialite (Hillebrand) 5,136,000,000 years. Mackintoshite (Hillebrand) 3,894,000,000 years. Nivenite (Mackintosh) 1,671,000,000 years. Fergusonite (Mackintosh) 10,350,000,000 years. Fergusonite (Mackintosh) 2,967,000,000 years. The list might be extended still further, but it is full enough as it stands. The minerals are all from one deposit, which is of about the same geologic age as the Connecticut uraninite studied by Ruther- ford, and yet the figures vary enormously, even for a single species. The assumption that lead is derived from uranium may be correct; but that all the lead in a given mineral had that origin is most doubt- ful. In the evolution of the chemical elements lead probably existed before uranium, and, being more stable, was developed in larger quantities. Magmatic lead, as represented by galena, is common in pegmatites, and may easily have become entangled with other minerals as an occluded impurity when crystallization first took 1 Am. Jour. Sci., 4th ser., vol. 23, 1907, p. 86. 2 Bull. Geol. Soc. America, vol. 19, 1908, p. 134. See also F. Zambonini, Atti R. accad. Lincei, 5th ser., vol. 20, pt. 2, 1911, p. 131; and R. W. Lawson, Univ. Durham Phil. Soc. Proc., vol. 5, 1913, p. 26. THE MOLTEN MAGMA. 319 place. This possibility is pointed out by Becker very clearly. The uranium-lead ratio is of very questionable value in computing the age of minerals. Similar objections apply to the use of the helium-radium ratio when it is assumed that all the helium was generated by radioactive decay. Helium is found in the nebulas, the hotter stars, and the sun; and the sun contains lead also; but uranium, thorium, and radium have not yet been recognized in the solar spectrum. B. Hasselberg 1 in a careful comparison of the solar spectrum with that of uranium failed to detect its presence. P. G. Nutting 2 was similarly unsuc- cessful when he compared Exner and Haschek’s table of the spectrum of uranium with a 30-foot reproduction of the solar spectrum. 3 Furthermore, helium is not only found in minerals containing uranium, but also under other conditions. For example, in certain beryls Strutt 4 found much helium but no radioactive parent from which it might have been generated. The helium in such cases may have originated from unknown radioactive substances of such great instability that no trace of them remains unchanged, but this is pure speculation. A. Piutti 5 found that helium is generally present in minerals containing glucinum, but with no regular ratio between the two elements. He has also 6 shown that helium is absorbed by certain melted salts and minerals, and that its presence therefore tells nothing of their age. The permeability of quartz to helium, which is perceptible at 220° and very great at 1,100°, may have some bearing on the problem now before us. 7 That minerals should differ in their permeability, and also in their capacity for retaining helium is almost beyond question. Another difficulty is suggested by the work of Ellen Gleditsch, 8 who has shown that the ratio between radium and uranium in minerals is not constant. That ratio enters into many of the calculations relative to the age of radioactive minerals. A still greater difficulty appears when we take into consideration the presence of helium in the waters of many springs. From one spring at Santenay, in France, according to C. Moureu and A. Lepape, 9 17,845 liters of helium are brought to the surface in one year. To supply this quantity the radioactive decay of not less than 91 metric 1 K. Svensk. Vet. Akad. Handl., vol. 45, No. 5, p. 63, 1910. 2 See Becker, Bull. Geol. Soc. America, vol. 19, p. 123, 1908. 3 F. W. Dyson (Astron. Nachrichten, vol. 192, p. 82, 1912) has reported, somewhat doubtfully, lines of radium in the spectrum of the solar chromosphere. H. Giebeler (idem, vol. 191, p. 401, 1912) has detected radium and its emanation in the spectrum of the star Nova Geminorum 2. These observations need con- firmation. Recent investigations have failed to support them. * Proc. Roy. Soc., vol. 80A, 1908, p. 572. 6 Atti R. accad. Lincei, 5th ser., vol. 22, pt. 1, 1913, p. 140. s Jour. Chem. Soc., vol. 100, pt. 2, p. 88, 1911 (abstract). 7 See A. Jaquerod and F. L. Perrot, Compt. Rend., vol. 139, 1904, p. 789; vol. 144, 1907, p. 135. 8 Idem, vol. 148, 1909, p. 1451; vol. 149, 1909, p. 267. 9 Idem, vol. 155, 1912, p. 197. 320 THE DATA OF GEOCHEMISTRY. tons of radium, or 500,000,000 tons of pitchblende or thorianite would be required. From all these considerations it is evident that primordial or “fossil” helium must be taken into account, and also the possibility that the reaction by which uranium decays may be reversed under the enormous pressures and high temperatures exist- ing within the earth. 1 On the basis of that supposition we can imagine that some of the helium found in minerals may be only left- over material from the original reactions in which the heavier elements were formed. One other method for computing the age of minerals is based on radioactive phenomena. In certain minerals, micas for example, little colored rings are observed, surrounding a presumably radio- active nucleus. From measurements of those “pleochroic haloes” J. Joly and others 2 have computed ages comparable with those derived from the helium and lead ratios. The data, however, are not sharp, and it is doubtful whether much weight can be given to the calculations. Finally, the discordance between the foregoing computations and other methods of ascertaining the age of the earth is extraordinary. From chemical denudation, from paleontological evidence, and from astronomical data the age has been fixed with a noteworthy degree of concordance at something between 50 and 100 millions of years. 3 The high values found by radioactive measurements are therefore to be suspected until the discrepancies shall have been explained. 4 In his presidential address before the Geological Society of America in December, 1914, G. F. Becker brings forward strong arguments against the radioactive method of computing the age of the earth. 1 This possibility is recognized by Rutherford, op. cit., p. 194; by M. Levin, Zeitschr. Elektrochemie, vol. 13, 1907, p. 390; and also by Becker in the paper just cited. 2 See J. Joly and A. L. Fletcher, Philos. Mag., 6th ser., vol. 19, 1910, p. 630; and J. Joly and E. Rutherford, idem, vol. 25, 1913, p. 694. 3 See G. F. Becker, Smithsonian Misc. Coll., vol. 56, No. 6, 1910. « See J. Marckwald, Ber. Deutsch. chem. Gesell., vol. 41, 1908, p. 1559, for a summary of the subject of radioactivity. Madame M. S. Curie’s Traite de radioactivity, 2 vols., Paris, 1910, is also most important. In Zeitschr. Elektrochemie, vol. 13, 1907, pp. 369-406, is a series of papers forming a symposium upon the subject. A curious attempt to reconcile radioactive and erosional methods of computing time is due to F. C. Brown (Le Radium, October, 1912, p. 352), who suggests that the sodium of the ocean may have been derived from some unknown radioactive parent. This is speculation pure and simple. CHAPTER X. ROCK-FORMING MINERALS. PRELIMINARY STATEMENT. When a magma solidifies, it may do so either as a glass or as an aggregate of crystalline minerals. In the latter process, which is the first step in the general process of magmatic differentiation, and in which molecular diffusion plays an important part, each mineral is distinctly marked off in space and occupies a region of its own. It may not be pure; it may entangle, during its formation, particles of other substances, but its definiteness and integrity are none the less clear. Although more than a thousand distinct mineral species are known to science, only a relatively small number of them are in any sense abundant or to be reckoned as essential constituents of rocks. An igneous rock is usually a mixture of silicates, containing, as basic metals, potassium, sodium, calcium, magnesium, iron, and aluminum, with oftentimes free silica. Other substances are present only in quite subordinate proportions. There may be small quantities of phosphates, especially apatite, some fluorides, various free oxides, the titanium minerals, zircon, sulphides in trivial amount, and sometimes free elements, such as graphite or metallic iron; but these constitu- ents of a rock have only minor significance, except in some exceed- ingly rare instances. The exceptions need not be considered now. Each mineral species, using the word in its rigorous sense, is a defi- nite chemical entity, capable of formation only under certain distinct conditions, and liable to alteration in various ways. Each one may be studied as it exists in nature, with the alterations which it there undergoes; or it may be investigated synthetically, with reference to its possible modes of origin, or by analytical methods in order to determine what transformations it is likely to experience. Both methods, the experimental and the observational, furnish legitimate lines of attack upon geological problems. A mineral, with its associa- tions, is a record of chemical changes that have taken place, but they do not end its history. It is still subject to decay — that is, to trans- formations into other forms of matter, and their study, chemically or in the field, constitutes an important part of metamorphic geology. Alteration products are highly significant, but their investigation demands extreme caution. Errors of diagnosis have been common in 97270°— Bull. 616—16 21 321 322 THE DATA OF GEOCHEMISTRY. the past, both as to the nature of substances and with regard to their implications; and each reported case of alteration, therefore, should be submitted to the severest scrutiny. A compact muscovite, for example, may easily be mistaken, on superficial examination, for talc or serpentine ; and errors of that kind may deprive an otherwise good observation of all its meaning. Many compounds, identical with natural minerals, have been pre- pared by laboratory methods, which may either reproduce the condi- tions existing in nature or vary widely from them. Each substance can be made in several different ways, and so the results of experi- ment may or may not have geological significance. In one process the conditions of a cooling magma are exactly paralleled; whereas another may have no relation to the phenomena observed by the geologist. The correct interpretation of laboratory experiments is, therefore, an affair demanding nicety of judgment; and the discrim- ination between relevant and irrelevant data is not always easy. The synthesis of a mineral may be chemically important, and yet shed no light upon the problems of geology. Still, indirect testimony is often of value, and none of it should be rejected hastily. In the following pages the more important minerals of the igneous and metamorphic rocks will be considered individually, from the various points of view indicated in the preceding paragraphs. Im- portance and abundance, however, do not always go together. A relatively infrequent mineral may be important for what it signifies and therefore receive more attention here than some of the commoner species. In a general way the usual order of mineral classification will be followed, but not rigorously. In some cases, for petrographic purposes, two minerals may be studied consecutively which in a text- book upon mineralogy would be widely separated. The problems of par agenesis, which are all-important here, are quite independent of mineraiogical classification. The titanium minerals — rutile, ilmen- ite, perofskite, and titanite, for example — can be properly considered successively, although one is an oxide, two are titanates, and the fourth is a titanosilicate. Petrographically they belong together; mineralogically they do not. So much premised, we may go on to study the individual species, as follows, beginning with the free ele- ments, carbon and iron. The inclusion of diamond in this category may be justified by the fact that it is essentially a mineral of mag- matic origin. DIAMOND AND GRAPHITE. Diamond . — Pure or nearly pure carbon. Isometric. Atomic weight, 12; molecular weight, unknown. Specific gravity, 3.5. Atomic volume, 3.4. Hardness, 10. Colorless to black, with various shades of yellow, green, blue, red, and brown. The black carbonado ROCK-FORMING MINERALS. 323 has a specific gravity slightly below that of the pure diamond, rang- ing from 3.15 to 3.29. Fusibility unknown, probably above 3,000°. Combustible at high temperatures, between 800° and 850°, according to H. Moissan, 1 although oxidation begins at a point somewhat lower. The diamond has been produced artificially in several ways. R. S. Marsden, 2 in 1880, claimed to have obtained minute crystals from the solution of amorphous carbon in molten silver. J. B. Hannay, 3 by heating amorphous carbon with bone oil and metallic lithium, under great pressure, also secured a few crystals of carbon which appeared to be in the form of diamond. Moissan, 4 however, was the first to obtain unimpeachable results. He dissolved carbon in melted iron, and cooled the mass suddenly under pressure. From the cooled iron, undoubted crystals of diamond were isolated. J. Friedlander 5 dissolved graphite in fused olivine and obtained small diamonds, and R. von Hasslinger, 6 by solution of amorphous carbon in an artificial magnesium silicate magma, was similarly successful. A little later R. von Hasslinger and J. Wolff 7 repeated and varied this experiment, using different magmas in order to determine under what conditions the diamonds would be formed. Magnesia and lime appeared to favor the crystallization of the carbon, but a high proportion of silica in the magma seemed to act adversely. According to Hasslinger and Wolff, a carbide is probably first produced, from which, later, the carbon separates in adamantine form. L. Franck and Ettinger 8 claim to have found diamonds in hardened steel, and A. Ludwig 9 observed their formation when an electric current was passed through an iron spiral embedded in powdered gas carbon, in an atmosphere of hydrogen and under great pressure. In a later investigation Lud- wig 10 fused a mixture of carbon and iron in an electric stream, and then suddenly chilled the mass by admission to it of water under a pressure of 2,200 atmospheres. Under these conditions of pressure and instantaneous cooling the fused carbon solidified in the form of minute diamonds. With slow cooling the more stable graphite is produced. These observations accord with the 1 Compt. Rend., vol. 135, 1902, p. 921. 2 Proc. Roy. Soc. Edinburgh, vol. 11, 1880-81, p. 20. K. Chrustchofl (Zeitschr. anorg. Chemie, vol. 4, 1893, p. 472) also obtained diamonds from solution in silver. Molten silver, he says, can dissolve about 6. per cent of carbon. 3 Proc. Roy. Soc., vol. 30, 1880, pp. 188, 450. * Compt. Rend., vol. 116, 1893, p. 218. Also C. Friedel, idem, p. 224. See also Q. Majorana, Atti R. accad. Lincei, 5th ser., vol. 6, pt. 2, 1897, p. 141. 6 Abstract in Geol. Mag., 1898, p. 226. 6 Monatsh. Chemie, vol. 23, 1902, p. 817. i Sitzungsb. Akad. Wien, vol. 112, 1903, p. 507. 8 Chem. Centralbl., 1896, pt. 2, p. 573. From Stahl u. Eisen, vol. 16, p. 585. 9 Chem. Zeitung, vol. 25, 1901, p. 979. 19 Zeitschr. Elektrochemie, vol. 8, 1902, p. 273. 324 THE DATA OF GEOCHEMISTRY. recent conclusions of Moissan , 1 who finds that when carbon is raised to a high temperature at atmospheric pressure it volatilizes without fusion and on cooling always yields graphite alone. In Moissan’s work, however, external pressure is not applied. It is generated by internal expansion within the iron, when the surface of the latter is suddenly cooled. The addition of a little ferrous sulphide tQ the fused iron seems to increase the yield of diamonds. According to G. Rousseau, 2 diamond is formed at ordinary pres- sures when acetylene, generated from calcium carbide, is decomposed by an electric current at a temperature of about 3,000°. C. V. Bur- ton 3 claims to have obtained diamond crystals from solution in molten lead to which about 1 per cent of calcium had been added. Finally, Sir William Crookes 4 has detected diamonds in the ash of cordite which had been exploded in closed vessels. In the last instance the pressure generated must have been very high. In nature the diamond is ordinarily found in gravels and until recently little was known of its parent rock. It has also been discovered in several meteorites, as in the meteoric stones of Novo- Urei, Russia , 5 and Carcote, Chile , 6 and the meteoric iron of Canyon Diablo . 7 The Novo-Urei stone is essentially a mixture of oh vine, 67.48 per cent, with augite 23.82 per cent, and therefore resembles a peridotite. The Canyon Diablo iron contains nodules of iron sulphide, troilite, which recall Moissan’s latest experiments, and also graphite. For each occurrence the artificial production of diamonds furnishes a parallel — Hasslinger’s work in one case, Moissan’s in the other. The origin of the diamond as a mineral seems to be clearly indi- cated by the foregoing data. It is formed by crystallization from the solution of carbon in a fused magma, and the latter, in most cases, seems to have had the composition of a peridotite — an association which is also seen in the Novo-Urei meteorite. In the South African mines the diamonds occur in or near volcanic pipes, embedded in a decomposed rock, which has been described as a peridotitic tuff or breccia . 8 The volcanic character of this matrix or “blue ground” was early recognized, and several authorities, notably the late H. 1 Compt. Rend., vol. 140, 1903, p. 277. See also Annales chim. phys., 8th ser., vol. 5, 1905, p. 174. On diamonds in blast-furnace slag and the conditions of their possible formation, see H. Fleissner, Oesterr. Zeitschr. Berg-u. Hiittenw., vol. 58, 1910, pp. 521, 539, 550, 570. See also P. Neumann, Zeitschr. Elek- trochemie, vol. 15, 1909, p. 817. W. von Bolton has reported the recrystallization of diamond dust, under the influence of mercury vapor derived from sodium amalgam, Zeitschr. Electrochemie, vol. 17, p. 971, 1911. 2 Compt. Rend., vol. 117, 1893, p. 164. 3 Nature, vol. 72, 1905, p. 397. « Proc. Roy. Soc., vol. 76 A, 1905, p. 458. 5 M. Erofeef and P. Latschinoff, Jour. Russ. Chem. Soc., vol. 20, 1888, p. 185. Abstract in Jour. Chem. Soc., vol. 56, 1889, p. 224. e W. Will and J. Pinnow, Ber. Deutsch. chem. Gesell., vol. 23, 1890, p. 345. 7 G. A. Koenig and A. E. Foote, Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 413. 8 See E. Cohen, 5 Jahresb. Ver. Erdkunde, Metz, 1882, p. 129. ROCK-FORMING MINERALS. 325 Carvill Lewis, 1 have ascribed the origin of the diamonds to the sol- vent action of the molten peridotite magma upon the carbonaceous shales through which it has penetrated. In some cases, however, these shales are absent, and W. Luzi 2 has shown that when "blue ground” is fused at a temperature of about 1,770° the diamonds which it contains are perceptibly corroded. That is, the magma itself is proved to be a solvent of carbon which may just as well have come from below as from contact metamorphism. In Lewis’s papers it is pointed out that in a number of other regions diamonds are asso- ciated more or less closely with rocks of serpentinous — that is, perido- titic — character. T. G. Bonney, 3 however, has sought to prove that the true matrix of the Cape diamond is eclogite, from which he says the mineral has crystallized as an original constituent, just as zircon crystallizes from granite. The very intimate association of these diamonds with garnet lends support to this view. On the other hand, G. F. Williams 4 states that he crushed and examined 20 tons of eclogite at Kimberley and found no trace of diamonds. He also reports a Kimberley diamond which contained an inclusion of apophyllite. If the diagnosis was correct, it throws doubt upon the igneous origin of the gem, for apophyllite is a highly hydrous mineral. According to H. ,S. Harger 5 the Vaal Kiver diamonds are derived from andesitic lava, and H. Merensky 6 reports them in pegmatite and diabase. The diamonds recently discovered in Arkansas, however, are associated with a peridotitic rock closely resembling kimberlite. 7 1 Papers before the British Association in 1886 and 1887. In full, edited by T. G. Bonney, in Papers and notes on the genesis and matrix of the diamond, London, 1897. The suggestion that the shales are the source of the carbon is adopted from E. J. Dunn, Quart. Jour. Geol. Soc., vol. 37, 1881, p. 609. See also L. De Launay, Les diamants du Cap, Paris, 1897; G. F. Williams, The diamond mines of South Africa, New York, 1905, 2 vols.; Sir William Crookes, Diamonds, London and New York, 1909; and P. A. Wagner, Die diamantfiihrenden Gesteine Siidafrikas, Berlin, 1909. Wagner gives a full bibliography relative to South African diamonds. An English edition appeared in 1914. For bibliographic notes on diamond see J. A. Thomson, Econ. Geology, vol. 5, 1910, p. 64. Other memoirs on the South African diamonds are by R. Beck, Zeitschr. Deutsch. geol. Gesell., vol. 59, 1907, p. 275; F. H. Hatch, Nature, vol. 77, 1908, p. 224; J. P. Johnson, Trans. Inst. Min. and Met., vol. 17, 1908, p. 277; and F. W. Voit, Eng. and Min. Jour., vol. 87, 1909, p. 789. For a review of several memoirs upon South African diamond, see E. Kaiser, Zeitschr. Kryst. Min., vol. 51, p. 399, 1912. 2 Ber. Deutsch. chem. Gesell., vol. 25, 1892, p. 2470. s Proc. Roy. Soc., vol. 65, 1899, p. 223. Bonney’s view is accepted by A. L. Du Toit, Eleventh Ann. Rept. Geol. Commission, Cape of Good Hope, 1907, p. 135. G. S. Corstorphine (Trans. Geol. Soc. South Africa, vol. 10, 1907, p. 65) shows that the supposed eclogite, in which he found diamonds, consists really of garnet-pyroxene nodules which are inclosed in the kimberlite. These nodules are concretionary in character. 4 Trans. Am. Inst. Min. Eng., vol. 35, 1905, p. 440. Ann. Rept. Smithsonian Inst., 1905, p. 193. On an inclusion of garnet in diamond see J. R. Sutton, Nature, vol. 75, 1907, p. 488. 6 Trans. Geol. Soc. South Africa, vol. 12, 1910, p. 139. See also E. H. V. Melvill, idem, p. 205, on stones from the Roberts-Victor mine. e Zeitschr. prakt. Geologie, 1908, p. 155. 7 See G. F. Kunz and H. S. Washington, Am. Jour. Sci., 4th ser., vol. 24, 1907, p. 275; and H. D. Miser, Bull. U. S. Geol. Survey No. 540, 1914, p. 534. 326 THE DATA OF GEOCHEMISTRY. In Brazil diamonds are associated with hydromica schists and the peculiar form of quartzite known as itacolumite; and O. A. Derby 1 finds no evidence of olivine rocks anywhere in the diamond-bearing region. Similar conclusions have been reached by J. C. Br a rm or, 2 who states that the diamonds are not only obtained from gravels, but also directly from decomposing quartzite. He also gives a full list of the associated minerals. Furthermore, near Bellary, Madras Presidency, India, M. Chaper 3 found the diamond to be apparently derived from a pegmatite consisting of rose-colored orthoclase and epidote. Near Inverell, New South Wales, T. W. Edgeworth David 4 found diamonds in a matrix of hornblende diabase. In short, though much evidence points to an igneous origin for the diamond, it is not necessary to assume that the same magma has yielded it in all cases. 5 Graphite. — Carbon, more or less impure. Rhombohedral. Atomic weight, 12; molecular weight probably below that of diamond. Specific gravity, 2.255. Atomic volume, 5.5. Hardness, 1 to 2. Color, steel gray to black. Fusibility unknown, probably above 3,000°. Combustible at temperatures between 650° and 700°. 6 Graphite is easily produced artificially. It is a common constituent of furnace slags, being derived from the fuel. On a commercial scale it is made by heating coke in the electric furnace, in which process, according to E. G. Acheson, 7 a carbide, possibly carborundum, SiC, is first formed. 0. Mulhauser 8 has shown that when carborundum is strongly heated the silicon is vaporized, leaving graphitic carbon behind. These reactions, connected with Moissan’s discovery 9 of car- borundum in the Canyon Diablo meteorite, associated with graphite and diamond, may have some geological significance. The fact that 1 Am. Jour. Sci., 3d ser., vol. 24, 1882, p. 34; Jour. Geology, vol. 6, 1898, p. 121. For the minerals asso- ciated with Brazilian diamond see E. Hussak, Min. pet. Mitt., vol. 18, 1898-99, p. 334; and also in Zeitschr. prakt. Geologie, 1906, p. 318. According to Hussak, the minerals of the Brazilian diamond sands are those derived from granites, gneisses, and older schists, such as amphibolite. An important earlier paper upon Brazilian diamonds is by C. Heusser and G. Claraz, Zeitschr. Deutsch. geol. Gesell., vol. 11, 1859, p. 448. Two later papers by Derby, relative to the genesis of the diamond, are in Jour. Geology, vol. 19, p. 627, 1911; vol. 20, 1912, p. 451. 2 Am. Jour. Sci., 4th ser., vol. 31, 1911, p. 480. 3 Compt. Rend., vol. 98, 1884, p. 113. More fully, in Bull. Soc. g6ol. France, 3d ser., vol. 14, 1885-86, p. 330. The description of this pegmatite suggests a resemblance to the unakite of Virginia and North Carolina. 4 Rept. Brit. Assoc. Adv. Sci., 1906, p. 562. See also Chem. News, vol. 96, 1907, p. 146. According to J. A. Thompson (Geol. Mag., 1909, p. 492), the matrix of the Inverell diamonds is dolerite. 5 An excellent monograph on the diamond, by E. Boutan, forms a volume in Fremy’s Encyclopedic chimique, Paris, 1886. It concludes with a very full bibliography. On diamonds in California, see H. W. Turner, Am. Geologist, vol. 23, 1899, p. 182. For a theoretical discussion on the genesis of the diamond, see A. Koenig, Zeitschr. Elektrochemie, vol. 12, 1906, p. 441. 6 H. Moissan, Compt. Rend., vol. 135, 1902, p. 921. On the specific gravity of graphite see H. Le Chatelier and S. Wologdine, Compt. Rend., vol. 146, 1908, p. 49. On its coefficient of expansion, A. L. Day and R. B. Sosman, Jour. Washington Acad. Sci., vol. 2, 1912, p. 284. These two papers relate to the definiteness of graphite as a species. 7 Jour. Franklin Inst., vol. 147, 1899, p. 475. 8 Zeitschr. anorg. Chemie, vol. 5, 1894, p. 111. 9 Compt. Rend., vol. 140, 1903, p. 405. ROCK-FORMING MINERALS. 327 graphite is often found in meteorites proves that it has not neces- sarily an organic origin, an assumption which is sometimes made. Graphite has also been prepared by passing vapors of carbon bisul- phide or carbon tetrachloride over hot iron, but these processes seem to have little or no geological significance. Whether such sub- stances occur in volcanic emanations is so far a matter of pure specu- lation. So also is E. Weinschenk’s suggestion 1 that metallic car- bonyls, rising from geat depths, may yield graphite by their decom- position. None of these compounds has been identified in nature, and it is more than doubtful whether they could exist at magmatic temperatures. J. Walther 2 is inclined to attribute the Ceylon graph- ite to derivation from carboniferous vapors rising from the interior of the earth, and it is possible that hydrocarbons might yield the mineral. M. Diersche , 3 studying the same field, ascribes the forma- tion of the graphite to the infiltration of liquid hydrocarbons and their decomposition by heat. W. Luzi 4 has shown that amorphous carbon can be converted into graphite by strong heating in melted potash glass containing calcium fluoride and water. In other words, graphite can occur in a silicate magma, either in consequence of its contact with carbonaceous matter or as an original constituent brought up from below. In fact, graph- ite often originates as a product of contact metamorphism. L. Jaczewski 5 regards the Siberian mineral as having been formed by just such a transformation of coaly matter in eruptive magmas; but there are many occurrences of graphite that can not be accounted for in this way. Weinschenk , 6 for example, cites instances of an associa- tion of graphite with the higher oxides of iron and manganese, which amorphous carbon or the hydrocarbons distilled during contact of a magma with coal would reduce to lower forms. In these cases the metamorphosis of carbonaceous shales can hardly be assumed . 7 From what has been said it is evident that graphite may originate in diverse ways, and that in some cases its mode of formation is exceedingly obscure. Its commonest occurrences are in the crystal- line schists, in which it often seems to replace mica. Graphitic granite, gneiss, mica schist, and quartzite are all well known, and the Laurentian limestones of Canada contain large quantities of the mineral. The graphite of the adjacent Adirondack region is attrib- uted by E. S. B as tin 8 to the dynamic metamorphism of carbonaceous 1 Compt. rend. VIII Cong. g6ol. intemat., vol. 1, 1900, p. 447. 2 Zeitschr. Deutsch. geol. Gesell., vol. 41, 1889, p. 359. For a full account of the Ceylon graphite see A. K. Coom&ra-Swamy, Quart. Jour. Geol. Soc., vol. 56, 1900, p.609. This paper contains a valuable bibliography. 3 Jahrb. K.-k. geol. Reichsanstalt Wien, vol. 48, 1898, p. 274. * Ber. Deutsch. chem. Gesell., vol. 24, 1891, p. 4093. Zeitschr. Naturwissenschaften, vol. 64, 1891, p. 224. 5 Neues Jahrb., 1901, Band 2, ref., p. 74. « Compt. rend. VIII Cong. g6ol. intemat., vol. 1, 1900, p. 447. 2 On the formation of graphite in certain soils see W. Heinisch, Sitzungsb. K. Akad. Wiss. Wien, vol. 120, Abth. II b, 1911, p. 85. 3 Econ. Geology, vol. 5, 1910, p. 134. 328 THE DATA OF GEOCHEMISTRY. sediments. T. H. Holland, 1 however, has described an elseolite syenite from India in which graphite appears to be an original mineral; and Moissan 2 examined a pegmatite of unknown locality and reached a similar conclusion. Graphite is also found in the iron-bearing basalts of Ovifak, Greenland, embedded in feldspar and associated with native iron. 3 Graphite, then, sometimes appears as a direct separa- tion from a magma, under conditions which preclude the supposition of an organic origin, or interpretation as a result of metamorphic action. NATIVE METALS. Native iron. — Isometric. Atomic weight, 55.9; molecular weight unknown. Specific gravity, 7.3 to 7.8, dependent upon the impuri- ties. Atomic volume, 7.2. Color, steel gray to black. Malleable. Luster, metallic. Hardness, 4 to 5. Magnetic. Minute grains of native iron are not uncommon in certain eruptive rocks, especially in basalts. They were first identified by T. Andrews 4 in the basalt of Antrim, Ireland. More recently they have been found by G. H. Cook 5 in the trap rocks of New Jersey; by G. W. Hawes 6 in the dolerite of Dry River, near Mount Washington, New Hampshire; by F. Navarro 7 in the basalt of Gerona, Spain; and by F. F. Horn- stein 8 in basalt near Cassel, Germany. In the New Hampshire locality they occur inclosed in grains of magnetite, suggesting a secondary derivation of the latter mineral from the metal. There are also a number of other European occurrences. 9 E. Hussak 10 found particles of native iron in an auriferous gravel in Brazil; and A. Daubree and S. Meunier 11 have described small masses of the metal from gold washings near Berezovsk, in the Ural. These masses were notable because of the fact that they contained traces of platinum, but no nickel. Their specific gravity was 7.59. The most remarkable occurrence of native iron, however, is that discovered by A. E. Nordenskiold 12 in 1870, at Ovifak, Disco Island, 1 Mem. Geol. Survey India, vol. 30, 1901, p. 201. 2 Compt. Rend., vol. 121, 1895, p. 538. 3 See K. J. V. Steenstrup, Mineralog. Mag., vol. 6, 1884, p. 1; and J. Lorenzen, idem, p. 14. Graphite from inclusions in basalt is also described by R. Brauns, Centralbl. Min., Geol. u. Pal., 1908, p. 97. On inorganic graphite from Lapland, see O. Stutzer, idem, 1907, p. 433. In Zeitschr. prakt. Geologie, 1910, p. 10, Stutzer has a long article on graphite deposits and their origin. See also A. N. Winchell, Econ. Geology, vol. 6, 1911, p. 218. On the graphite of southeastern Pennsylvania, of metamorphic origin, see B. L. Miller, Econ. Geology, vol. 7, 1912, p. 762. On the conversion of amorphous carbon into graphite see C. W. Arsem, Jour. Ind. Eng. Chem., vol. 3, 1911, p. 799. 4 Rept. Brit. Assoc., 1852, pt. 2, p. 34. 5 Ann. Rept. Geol. Survey New Jersey, 1874, p. 56. e Am. Jour. Sci., 3d ser., vol. 13, 1877, p. 33. 7 Geol. Centralbl., vol. 7, 1905, p. 184. 8 Centralbl. Min., Geol. u. Pal., 1907, p. 276. 8 See for example, A. Schwantke, Centralbl. Min., Geol. u. Pal., 1901, p. 65, and M. Seebach, idem, 1910, p. 641. 10 Bol. Comm. geog. e geol. Sao Paulo, No. 7. 1890, p. 14. 11 Compt. Rend., vol. 113, 1891, p. 172. 12 Geol. Mag., 1872, pp. 460, 516. ROCK-FORMING MINERALS. 329 Greenland. Here large masses of iron, up to 20 tons in weight, had been weathered out like bowlders from the basalt, and in the rock itself lenticular and disklike pieces of the metal were still embedded. At first the iron was thought to be meteoric, but it has since been proved to be of terrestrial origin. 1 In nearly all respects it resembled meteoric iron, for it gave the Widmannstatten figures when etched, contained iron chloride, and was associated with magnetic pyrites and graphite. Schreibersite, the iron phosphide, which is common in meteorites, is, however, absent from the Ovifak masses. In the sample examined by Moissan 2 graphite, amorphous carbon, and grains of corundum were found. This Ovifak iron is somewhat variable in composition, as the numerous analyses of it show. 3 The following analyses by J. Law- rence Smith are enough to indicate its general character: Analyses of native iron from Ovifak , Greenland. A. External oxidized coating of a large mass. Specific gravity, 5. B. Particles of iron from interior of the mass A. Specific gravity, 6.42. C. Malleable nodule from dolerite. Specific gravity, 7.46. D. An irregular mass. Specific gravity, 6.80. A B c D FeoCL 76. 21 Fe 16. 56 93. 16 90. 17 88. 13 Ni 1. 08 2. 01 6.50 2. 13 Co .48 .80 .79 1. 07 Cu .08 .12 .13 .48 s. 1. 12 .41 .36 P .14 .32 .25 c 1.36 2. 34 2.33 Cl .02 . 08 MgO Trace. Si0 2 1.54 Silicates 4. 20 H 2 0 4. 50 101. 53 99. 18 99. 13 99. 03 The terrestrial nature of this iron is abundantly proved by the observations of Steenstrup, who found it disseminated throughout large bodies of basalt in place. It is, therefore, a part of the rock itself, but concerning its origin there has been much discussion. Was it present in the original magma or reduced by carbonaceous matter on its way up from below? The latter supposition is admissible, for Daubree, 4 by fusing a Iherzolite with carbon, obtained pellets of 1 There is abundant literature on this subject. See especially K. J. V. Steenstrup, Mineralog. Mag., vol. 6, 1884, p. 1; J. Lorenzen, idem, p. 14; J. Lawrence Smith, Annales chim. phys., 5th ser., vol. 16, 1879, p. 452; and A. Daubree, Etudes synthetiques de geologie experimentale, 1879, p. 555. 2 Compt. Rend., vol. 116, 1893, p. 1269. 3 See the memoirs, already cited, by Nordenskiold, Lorenzen, and Smith. Also E. S. Dana, System of mineralogy, 6th ed., p. 28. 4 Etudes synthetiques de geologie experimentale, 1879, pp. 517, 574. 330 THE DATA OF GEOCHEMISTRY. metallic iron, containing nickel and almost identical in composition with the specimens from Greenland. Furthermore, as Daubree observes, beds of lignite are found on Disco Island, and graphite is closely associated with the native iron. The other alternative, how- ever, is not excluded from consideration, and it may be that the iron came as such from great depths below the surface to teach us that the earth is essentially a vast meteorite and that its interior is rich in uncombined metals. 1 If the reduction theory held, we should expect to find similar occurrences of native iron wherever basalts or peridotite had penetrated carbonaceous strata. The rarity of the substance would seem to indicate a profounder origin. In several localities metallic grains or nodules which approach native nickel in composition have been found in gravels. In mete- orites the nickel rarely exceeds 6 or 7 per cent, but in these terrestrial products its proportion is usually much higher. From the drift of Gorge Fiver on the west coast of New Zealand W. Skey 2 obtained grains of this character, which were associated with magnetite, tin- stone, native platinum, etc. This awaruite, as Skey named it, is derived, according to G. H. F. Ulrich, 3 from neighboring serpentines or peridotites. The j osephinite of W. H. Melville 4 from placer gravels in Josephine and Jackson counties, Oregon, forms pebbles up to sev- eral grams in weight and also occurs near large masses of serpentine. Its specific gravity is 6.204. In the sands of the Elvo, near Biella, Piedmont, A. Sella 5 found minute grains of a similar substance, but its geological origin was not determined. Their specific gravity was 7.8. Souesite consists of similar grains, found by G. C. Hoffmann 6 in sands of the Fraser Fiver, in British Columbia. They were asso- ciated with native platinum, iridosmine, gold, etc., and had a specific gravity of 8.215. These grains are doubtless derived from perido- tite. Still more recently a similar nickel iron from the south fork of Smith Fiver, Del Norte County, California, has been described by G. S. Jamieson, 7 who has also reexamined the mineral from Oregon. The analyses are as follows: 1 See also E. B. de Chancourtois, Bull. Soc. geol. France, vol. 29, 1872, p. 210. C. Winkler (Ber. Math, phys. Classe, K. sachs. Gesell. Wiss., February 5, 1900) suggests that iron and nickel may have been brought up from below as carbonyls, Ni(CO) 4 , Fe(CO) 5 , and Fe 2 (CO) 7 — compounds which decompose easily, depositing their metals in the free state. Compare Weinschenk’s suggestion as to graphite, ante, p. 327. 2 Trans. New Zealand Inst., vol. 18, 1885, p. 401. 3 Quart. Jour. Geol. Soc., vol. 46, 1890, p. 619. 4 BuH. U. S. Geol. Survey No. 113, 1893, p. 54. sCompt. Rend., vol. 112, 1891, p. 171. 6 Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 319. 7 Idem, p. 413. Jamieson urges that the original name awaruite should be used for all these irons. Awaruite is also reported from the Yukon by R. A. A. Johnston, Summary Rept. Geol. Surv. Canada, 1910-11, p. 256. ROCK-FORMING MINERALS. 331 Analyses of nickel iron. A. Awaruite, Skey. B. JosepMnite, Melville. C. Josephinite, Jamieson, D. Del Norte County, Jamie- son. E. Souesite, Hoffmann. F. Piedmont. Analyzed for Sella by Mattirolo. A B c D E F Ni 67. 63 60. 45 68. 61 68. 46 75. 50 75.2 Co . 70 .55 1. 07 1.07 None. Fe 31.02 23.22 19. 21 18. 97 22.02 26.6 Fe 7 S 8 .55 s .22 .05 .05 Cu .50 .59 .56 1.20 As .23 P .04 .04 Chromite and magnetite .12 Si0 2 .43 .10 .19 Silicates 12.26 1. 16 Insoluble 9. 45 9. 97 MgO .50 .44 H 2 0 at 100° .81 H 2 0 above 100° 1. 12 Cl .04 co 2 Tracer Volatile matter . 70 100. 00 100. 55 99. 62 99. 75 99. 88 101.8 The silicate in Melville’s analysis was mainly serpentine, with what appeared to be an impure bronzite. The probable derivation of the nodules from peridotite is thus materially emphasized. With these substances two meteorites only, or supposed meteorites, can be com- pared. That found in an Indian mound in Oktibbeha County, Mis- sissippi, contained 59.69 per cent Ni and 37.97 per cent Fe; and that from Santa Catarina, Brazil, carried 63.69 Fe with 33.97 Ni. These masses, however, are only presumably, not certainly, meteoric. Occasionally native iron is found of secondary origin produced by the obvious reduction of iron compounds. On North Saskatchewan River, 70 miles from Edmonston, beds of lignite have burned, reduc- ing the neighboring clay ironstone to metallic iron. According to J. B. Tyrrell, 1 masses of iron which weigh from 15 to 20 pounds can be picked up in this locality. G. C. Hoffmann 2 has described spher- ules of iron in limonite, found in fissures in quartzite on St. Josephs Island, Lake Huron; and again from a pegmatite of Cameron Township, Ontario. 3 The exact origin of these Canadian irons is not clear. Finally, E. T. Allen 4 has analyzed soft, malleable iron from borings at three points in Missouri, where it occurred in sedi- mentary rocks not far from beds of coal. The following analyses 1 Am. Jour. Sci., 3d ser., vol. 33, 1887, p. 73. 2 Trans. Roy. Soc. Canada, vol. 8, pt. 3, 1890, p. 39. 3 Ann. Rept. Geol. Survey Canada, vol. 6, 1895, p. 23 R. 4 Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 99. Other occurrences of naturally reduced ironare reported by A . A . Inostranzeff , Geol. Zentralbl. , 1908, p . 611 , from Russian Island, near Vladivostok, and by E . Pf iwosnik, Oesterr. Zeitschr. Berg- u. Hiittenw., vol. 58, 1910, p. 327, from Shotley Bridge, England. On iron formed under peat by the reduction of bog iron ore see A. E. Kupffer, Chem. Zentralbl., 1913, p. 55. 332 THE DATA OF GEOCHEMISTRY. of these products will serve to show the great difference between them and the supposedly magmatic irons described in the preceding pages: Analyses of native iron of secondary origin. A. From St. Josephs Island, Hoffmann. Specific gravity, 6.8612. B. From Cameron Township, Ontario. Analysis by Johnston for HofEmann. Specific gravity, 7.257. C. From Cameron, Missouri, Allen. D. From Weaubleau, Missouri, Allen. E. From Holden, Missouri, Allen. A B c D E Fe 88.00 .10 .21 .51 .09 .12 .96 (?) 90.45 Trace. None. .75 None. Undet. Undet. 99.16 99.39 97.10 Ni Co Mn Cu S P .207 .065 .37 Undet. .13 .31 Undet. .176 1.65 c Si0 2 Insoluble 9.76 Undet. 7.26 Organic matter 99.75 98.46 99. 802 99.83 98. 926 Not only iron but other native metals may occur as primary con- stituents of igneous rocks. Platinum, with its companions, osmium, iridium, rhodium, ruthenium, and palladium, are associated with chromite and olivine in peridotites. 1 W. Moricke 2 has found pri- mary gold in a pitchstone from Guanaco, Chile, and G. P. Merrill 3 * has described a granite from Sonora in which it also appears. Still other examples are cited by R. Beck. 4 The metallic constituents of magmas, however, have received very little attention so far, and their number may be greater than it is now supposed to be. SULPHIDES. Pyrite . — Isometric. Composition, FeS 2 . Molecular weight, 120. Specific gravity, 4.95 to 5.10. Molecular volume, 24. Color, brass- yellow; luster, metallic. Hardness, 6 to 6.5. Pyrrhotite . — Hexagonal and orthorhombic. Two modifications are known. Composition uncertain, varying from Fe 7 S 8 to Fe u S 12 . Specific gravity, 4.6. Color, bronze-yellow to copper-red; luster, metallic. Magnetic. Hardness, 3.5 to 4.5. Whether troilite, FeS, which is a common mineral in meteorites, is identical with pyrrhotite or not is a disputed question. 5 £ 1 See J. F. Kemp, Bull. U. S. Geol. Survey No. 193, 1902, for a complete summary of our knowledge con- cerning native platinum, with many bibliographic references. 2 Min. pet. Mitt., vol. 12, 1891, p. 195. 3 Am. Jour. Sci., 4th ser., vol. 1, 1896, p. 309. 4 Lehre von den Erzlagerstatten, 2d cd., 1903. See also W. H. Weed, Eng. and Min. Jour., vol. 77, 1904, p. 440, and R. W. Brock, idem, p. 511. 6 See S. Meunier, Annales chim. phys., 4th ser., vol. 17, 1869, p. 36, and G. Linck, Ber. Deutsch. chem. Gesell., vol. 32, 1899, p. 895. ROCK-FORMING MINERALS. 333 Both pyrite and pyrrhotite are common though minor accessory constituents of igneous rocks. Pyrite is found under a great variety of associations, but pyrrhotite is more characteristic of the ferromag- nesian varieties, such as gabbro, diabase, diorite, and basalt. Pyrrhotite has been observed as a furnace product, and both species can be made artificially by various processes. Those which explain the formation of sulphides in sedimentary rocks will be considered in another connection, but the following experimental data bear upon their occurrence in igneous formations. J. Durocher, 1 by mingling the vapor of iron chloride with hydrogen sulphide in a porcelain tube heated to redness, obtained small crystals of pyrite. By heating magnetite to whiteness in hydrogen sulphide, T. Sidot 2 produced crystals which appeared to be identical with troilite. Troilite was also formed by R. Lorenz, 3 who heated iron to redness in a stream of H 2 S. C. Doelter, 4 on the other hand, by the same reaction, and also with amorphous ferric oxide or hematite instead of metallic iron, obtained pyrite. When ferrous carbonate or sulphate was used, troilite was formed. All of these methods are general. With other metals or their salts other crystallized sulphides, identical with natural minerals, can be produced. In brief, gases or vapors which exist in volcanic exhalations can so react upon one another as to develop crystalline sulphides. The latter appear in or upon the solidified rocks, but preferably in rocks which have cooled under pressure. By pressure the reacting vapors are confined within the magma, and can not readily escape. Metallic sulphides, fairly crystallized, can also be formed in the wet way, when appropriate mixtures are heated together in sealed tubes. H. de Senarmont 5 heated various metallic solutions with hydrogen sulphide or alkaline sulphides in this manner with great success, and when iron salts were taken pyrite was formed. C. Geitner 6 also ob- tained pyrite by heating powdered basalt with water and sulphurous acid to 200°. Doelter 7 prepared pyrite by heating hematite, mag- netite, or siderite with hydrogen sulphide and water for 72 hours to 80° or 90°. When the same investigator 8 heated ferrous chloride with sodium carbonate, water, and hydrogen sulphide for 16 days to 200° he obtained pyrrhotite, provided that air was excluded from his tubes. In presence of air pyrite was formed. 1 Compt. Rend., vol. 32, 1851, p. 823. For an earlier synthesis of pyrite see F. Wohler, Liebig’s Annalen, vol. 17, p. 260, 1836. a Idem, vol. 66, 1868, p. 1257. * Ber. Deutsch. chem. Gesell., vol. 24, 1891, p. 1504. 4 Zeitschr. Kryst. Min., vol. 11, 1886, p. 30. 6 Compt. Rend., vol. 32, 1851, p. 409. s Ann. Chem. Pharm., vol. 129, 1864, p. 350. 7 Zeitschr. Kryst. Min., vol. 11, 1886, p. 30. 8 Min. pet. Mitt., vol. 7, 1885-86, p. 535. 334 THE DATA OF GEOCHEMISTRY. According to W. Feld, 1 when iron salts are precipitated by an alkaline polysulphide, ferrous sulphide and sulphur are thrown down. If the solution is then neutralized, or made very feebly acid, and boiled, the precipitate is rapidly transformed into the bisulphide. Alkaline substances retard or hinder the transformation, reducing agents hasten it. In all formations of pyrite by the wet way the monosulphide seems to be first produced. In a still more elaborate investigation E. T. Allen, J. Johnston, J. L. Crenshaw, and E. S. Larsen 2 report that pyrrhotite is formed by the direct union of iron and sulphur and also by the dissociation of pyrite in an atmosphere of H 2 S at a temperature of 550°. At 575°, the reverse change takes place, and pyrite is again formed. Pyrrhotite exists in two modifica- tions, hexagonal below 138°, orthorhombic above that transition temperature. The variation of pyrrhotite from troilite is ascribed to the presence of sulphur in “ solid solution” in the monosulphide. 3 In meteorites the excess of metallic iron renders the formation of pure troilite possible. Pyrite was produced by Allen and his colleagues not only from pyrrhotite, but also by the action of hydrogen sulphide upon solutions of iron. From acid solutions, at 100°, under pressure, its relatively unstable isomer, marcasite was formed. Warmer alkaline solutions yielded pyrite. At 450° marcasite is transformed into pyrite, and therefore it can not occur as a magmatic mineral. Marcasite is only found in sedimentary formations and metalliferous veins. Fossil shells consisting entirely of marcasite are well known, and inte- mediate mixtures of pyrite and marcasite are common. The two species probably differ in molecular arrangement, but the evidence upon this point is far from conclusive. Various structural formulae have been proposed for them, but none has been definitely estab- lished. 4 Pyrrhotite and marcasite both alter into pyrite and all three species alter into limonite, goethite, hematite, and sulphates of iron. Perfect pseudomorphs of limonite after pyrite are common. 5 Another modification of FeS 2 , black and amorphous, has been de- scribed by B. Doss, 6 who names it melnikovite. 1 Zeitschr. angew. Chemie, vol. 24, 1911, p. 97. 2 Yearbook Carnegie Inst. Washington, 1910, p. 104; Am. Jour. Sci., 4th ser., vol. 33, p. 169, 1912. Many references to literature are given. See also Allen, Jour. Washington Acad. Sci., vol. 1, p. 170, 1911; and Allen and Crenshaw, Am. Jour. Sci., 4th ser., vol. 38, p. 393, 1914. s The variation may possibly be due rather to admixtures of a higher sulphide of iron, Fe 2 S 3 or Fe3S4, compounds which are not definitely known but are theoretically rational. * See E. Weinschenk, Zeitschr. Rryst. Min., vol. 17, 1890, p. 501; A. P. Brown, Proc. Am. Philos. Soc., vol. 33, 1894, p. 225; and H. N. Stokes, Bull. U. S. Geol. Survey No. 186, 1901. Stokes describes many elaborate experiments upon the relative solubility of pyrite and marcasite in chemical reagents. See also G. W. Plummer, Thesis, Univ. Pennsylvania, 1910. 5 For a full discussion of the alterations of pyrite see A. A. Julien, Annals New York Acad. Sci., vol. 3, 1886, p.365; vol. 4, 1887, p. 125. A paper on the origin of pyrite, by A. R. Whitney, is in Econ. Geology, vol. 8, 1913, p. 455. 6 Neues Jahrb., Beil. Band 33, 1912, p. 662. EOCK-FORMING MINERALS. 335 Each of these synthetic processes finds some equivalent in nature. Dry gases, wet gases, and alkaline solutions charged with hydrogen sulphide can assist in producing the minerals which are now under consideration, with other rarer species of the same class. The magmas contain the reagents, and the reactions, or reactions like those just described, naturally follow. In most cases the sulphides appear as secondary minerals, but they are sometimes primary. J. H. L. Vogt 1 has shown that sulphides are actually soluble in silicate magmas, especially at the higher temperatures, and that they are among the earliest minerals to crystallize. Certain of the pyrrhotite deposits of Norway he regards as the direct products iof / .m«igm^,tic segregation. Several other sulphides occasionally appear ras priuto^y -minerals in igneous rocks. Molybdenite, MoS 2 , is common in granites, and J. F. Kemp, 2 in a pegmatite dike in British Columbia, found masses of bomite, which appeared to be an original constituent of the rock. In the augite syenite of Stoko, near Brevik, Norway, the arsenide, lollingite, FeAs 2 , appears to have crystallized before the feldspar. The pegmatites of that region, as described by W. C. Brogger, also contain molybdenite, zinc blende, pyrite, galena, and chalcopyrite. 3 Some of these occurrences, and many occurrences of pyrite also, are doubtless secondary. FLUORIDES. Fluorite. — Isometric. Composition, CaF 2 . Molecular weight, 78.1. Specific gravity, 3.18. Molecular volume. 24.5. Hardness, 4. Colorless, yellow, red, blue, green, purple, violet, etc. Fluorite, although most abundant as a vein mineral and in sedi- mentary formations, is also found as a minor accessory in granite, gneiss, quartz porphyry, syenite, elseolite syenite, and the crystalline schists. W. C. Brogger 4 reports it, both as an early separation in the augite syenites of Norway and also as a contact mineral. It sometimes appears on volcanic lavas as a sublimation product, or as the result of the action of fluoriferous gases upon other minerals. 5 6 It 1 Die Silikatschmelzlosungen, pt. 1, 1903, p. 96. See also Zeitschr. prakt. Geologie, 1898, p. 45; and Trans. Am. Inst. Min. Eng., 1901, p. 131. For sulphides in slags, see J. H. L. Vogt, Mineralbildung in Schmelz- massen, Christiania, 1892. See also J. E. Spurr, Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 306, on Alaskan pyrrhotite. A remarkable peridotite at East Union, Maine, containing 21.5 per cent of pyrrhotite, is described by E. S. Bastin in Jour. Geology, vol. 16, 1908, p. 124. 2 Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 182. See also W. H. Emmons, Bull. U. S. Geol. Survey No. 432, 1910, p. 42, on molybdenite in the granites of Maine. R. Brauns (Centralbl. Min., Geol. u. Pal., 1908, p. 97) found molybdenite in inclusions in basalt. O. Stutzer (Zeitschr. prakt. Geologie, 1907, p. 371) has described magmatic bomite from South Africa. Chalcopyrite and bomite as primary minerals in a monzonitic dike near Apex, Colorado, havebeen reported by E. S. Bastin and J. M. Hill. Econ. Geology, vol. 6, p. 468, 1911. See also E. Howe, Econ. Geology, vol. 10, 1915, p. 298. 3 See Zeitschr. Kryst. Min., vol. 16, pt. 2, 1890, pp. 5-11. For very complete analyses of Norwegian pyrite, see E. Boettker, Rev. gdn. chim. pure et app., vol. 9, p. 323. * Zeitschr. Kryst. Min., vol. 16, pt. 2, 1890, p. 56. 6 Idem, vol. 7, 1883, p. 630. Abstract of memoir by A. Scacchi. For a study of the gases occluded by fluorite, see H. W. Morse, Proc. Am. Acad., vol. 41, 1906, p. 587. According to H. Becquerel and H. Moissan (Bull. Soc. chim., 3d ser., vol. 5, 1891, p. 154) free fluorine is sometimes present W. J. Hum- phreys (Astrophys. Jour., vol. 20, 1904, p. 266) found spectroscopic traces of yttrium and ytterbium in many fluorspars. G. Urbain (Compt. Rend., vol. 143, 1906, p. 826) also found terbium, gadolinium, dysprosium, and samarium. 336 THE DATA OF GEOCHEMISTRY. is also produced as a secondary mineral from the decomposition of various fluosilicates. It alters into calcite, being attacked by perco- lating waters containing calcium bicarbonate or alkaline carbonates. Crystallized calcium fluoride has been prepared by several processes, but they shed little light upon its presence in igneous rocks. 1 Several other fluorides are found associated with granites or peg- matites, such as tysonite, fluocerite, yttrocerite, etc. More important by far is the mineral cryolite, which forms a large bed in Greenland. According to F. Johnstrup, 2 it is a concretionary secretion in eruptive granite. A more recent writer, It. Baldauf, 3 regards the cryolite as having been formed by the action of fluoriferous gases upon the original granitic magma. Cryolite is also found sparingly at Miask, in the Urals, and in the granites of Pikes Peak, Colorado. 4 It is a double fluoride of aluminum and sodium, Na 3 AlF 6 . Fluorine com- pounds, it must be observed, are rarely found in eruptive rocks. They are especially characteristic of the deep-seated or plutonic rocks, where the gaseous exhalations have been retained under pressure, and are commonly regarded as of pneumatolytic origin. CORUNDUM. Bhombohedral. Composition, aluminum oxide, A1 2 0 3 . Specific gravity, 3.95 to 4.10; of the purest material, 4.0; molecular weight, 5 102 ; molecular volume, 25.5. Colorless when pure, but ordinarily col- ored yellow, gray, green, red, or blue by traces of impurity. Emery is a mixture of corundum with magnetite or hematite, and sometimes spinel. Fusible at 2,050° C., according to C. W. Kanolt. 6 Hard- ness, 9, thus ranking among natural minerals next to diamond. Crystallized alumina, artificial corundum, has been produced by various methods. These are well summarized in the works of Bour- geois and Fouque and Levy, and in the memoir by J. Morozewicz. 7 They may be briefly grouped as follows: First, by direct fusion of amorphous alumina. Second, by the crystallization of alumina from solution in various molten fluxes, such as potassium bichromate, sodium molybdate, borax, lead oxide, etc. Most of these processes find no equivalent in nature. Third, by the decomposition of alum- inum chloride or fluoride by water at high temperatures — methods 1 See the works by Brauns, Bourgeois, and Fouqud and Ldvy cited elsewhere in this chapter. 2 Cited by F. Zirkel, Lehrbuch der Petrographie, vol. 3, p. 444. The original memoir by Johnstrup is not within my reach. 3 Zeitschr. prakt. Geologie, 1910, p. 432. Baldauf gives a good description of the rarer minerals associated with the cryolite. See also O. B. Boggild, Zeitschr. Kryst. Min., vol. 51, 1913, pp. 591, 614. * W. Cross and W. F. Hillebrand, Bull. U. S. Geol. Survey No. 20. & The ordinary rounded-off atomic weights may be used for computations of molecular weights and volumes. 6 Jour. Washington Acad. Sci.,vol. 3, 1913, p. 315. Other determinations of the melting point are: Hem- pel, 1,880°; Moissan, 2,250°; and Ruff, 2,010°. 7 Fouqud and Levy, Synthese des mindraux et des roches, Paris, 1882. L. Bourgeois, Reproduction arti- ficielle des mindraux, in Fremy’s Encyclopddie chimique, vol. 2, 1st appendix. Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 23. ROCK-FORMING MINERALS. 337 which may shed some light upon the formation of corundum as a contact mineral, or as a constituent of metamorphic rocks. In some of these reactions boric acid plays a part. Fourth, by the decomposi- tion of other minerals, such as muscovite. Finally, by crystallization of artificial magmas. It is not necessary for our purposes to examine these processes in detail. It is enough to select from among them those which seem to be the most significant. P. Hautefeuille and A. Perrey, 1 for example, dissolved alumina in melted nepheline, and found that upon cooling the greater part of it crystallized out as corundum. The association of corundum with certain nepheline syenites can be rationally studied in the light of this observation. With leucite a similar result was obtained; but an artificial potassium nepheline gave no similar reac- tion. A. Brun 2 prepared corundum, together with anorthite, by heating a mixture of 40 parts silica, 37 lime, and 120 alumina to whiteness for three hours. Fusion of the mixture, however, gave him only glass. When the alumina was reduced to 23 parts, zoisite was formed. W. Bruhns 3 obtained corundum in the wet way by heating alumina for 10 hours to 300° in a platinum tube with water containing a trace of ammonium fluoride; but at 250° no crystalliza- tion took place. By similar reactions hematite, quartz, tridymite, and ilmenite were prepared. These experiments strengthen the sup- position that the fluorine compounds contained in volcanic exhala- tions may assist the natural formation of the minerals named. P. Hautefeuille’s synthesis of corundum 4 by the action of moist hydro- fluoric acid upon alumina at a red heat is another illustration of the same principle. It is typical of a considerable number of mineral syntheses. That the fluorides are not essential to the formation of corundum, however, is shown by the experiments of G. Friedel. 5 When amorphous alumina is heated to 450-500° with a solution of soda, corundum and diaspore, HA10 2 , are both produced. At 530- 535° corundum alone formed, and at 400° only diaspore. If the alumina contained a little silica, crystals of quartz appeared. By a similar reaction between ferric hydroxide and soda solution, Friedel obtained crystals of hematite. E. S. Shepherd and G. A. Kankin 6 converted precipitated alumina into crystalline corundum by simple heating at about 200°. From a geological standpoint some very important experiments upon the genesis of corundum are those of Morozewicz, 7 who studied 1 Bull. Soc. min., vol. 13, 1890, p. 147. 2 Arch. sci. phys. nat., 3d ser., vol. 25, 1891, p. 239. 8 Neues Jahrb., 1889, Band 2, p. 62. 4 Annales chim. phys., 4th ser., vol. 4, 1865, p. 153. 8 Bull. Soc. min., vol. 14, 1891, p. 8. 9 Am. Jour. Sci., 4th ser., vol. 28, 1909, p. 321. T Min. pet. Mitt., vol. 18, 1898, pp. 22-83. Also Zeitschr. Kryst. Min., vol. 24, 1895, p. 281. 97270°— Bull. 616—16 22 338 THE DATA OF GEOCHEMISTRY. the conditions of its deposition from a cooling magma. He worked with artificial magmas upon a rather large scale, using the furnaces of a glass factory in preparing his melts; and he found that when- ever the alumina, in comparison with the other bases, exceeded a cer- tain ratio, the excess, upon cooling the fused mass, crystallized out completely either as corundum, as spinel, as sillimanite, or as iolite. 1 The qualifying conditions are as follows: An alumosilicate magma in which the molecular ratio of the bases CaO, K 2 0, Na 2 0 is to A1 2 0 3 as 1:1 is said to be saturated with respect to alumina. If more alumina is present, the magma is super- saturated, and the excess will be deposited as one or another of the above-named minerals. If we write the general formula for the magma of H0.mAl 2 0 3 .7iSi0 2 the following rules are found to apply: First, if magnesia and iron are absent, and the value of n lies between 2 and 6, the excess of alumina will crystallize wholly as corundum; but if n is greater than 6, sillimanite, or sillimanite and corundum, will form. With magnesia or iron present in an amount above 0.5 per cent, and with n< 6, spinel is produced, or spinel and corundum together. With n>6, the magnesia and the excess of alumina will go to form iolite, or iolite and spinel. In each case the alumina in excess of the ratio RO : Al 2 0 3 : : 1 : 1 is completely taken up in the formation of the several species named. The balance of the alumina — the normal alumina, so to speak — will obviously appear in other minerals, such as anorthite, nepheline, alkali feldspars, etc., whose nature will depend upon the bases which happen to be asso- ciated with it, and also upon the proportion of silica. Previous to the appearance of Morozewicz’s memoir it was com- monly supposed, but without good reason, that corundum was not a true pyrogenic mineral. It was best known as occurring with meta- morphic rocks, and especially in limestones; and it had been observed as a product of contact action, although rarely. 2 When corundum was found in igneous rocks it was regarded as derived from acci- dental inclusions, and not as a primary separation from the magma. The work of Morozewicz modified these beliefs and shed new light upon the problems of petrology. The common association of corun- dum with spinel, iolite, sillimanite, andalusite, and kyanite at once became significant, and in accordance with the rules developed by Morozewicz. Pyrogenic corundum, according to A. Lagorio, 3 is found in alumo- silicate rocks only when the latter contain over 30 per cent alumina, 1 Cordierite. The name iolite has priority and is given preference by Dana. * K. Busz (Geol. Mag., 1896, p. 492) found corundum in contacts between granite and clay slate on Dart- moor in Devonshire. A. K. Coom&ra-Sw&my (Quart. Jour. Geol. Soc., vol. 57, 1901, p. 185) observed it at contacts between granite and micaceous quartzite near Morlaix, France. The corundum was there asso- ciated with sillimanite, andalusite, spinel, etc. On an occurrence of corundum in basalt see E. Schurmann, Sitzungsb. naturhist. Ver. preuss. Rheinlande u. Westfalens, 1911, pt. 2, p. 63 A. 8 Zeitschr. Kryst. Min., vol. 24, 1895, p. 285. This memoir contains abundant literature references upon the occurrence of corundum in igneous rocks. ROCK-FORMING MINERALS. 8S9 and such rocks are rare. Lagorio cites analyses of several examples, and Morozewicz 1 himself describes others. Kvschtymite is an anor- thite rock containing up to 59.5 per cent of corundum; a corundum syenite with 18.5 per cent consists largely of orthoclase and albite, and a corundum pegmatite with 35.4 per cent has similar composi- tion. All these rocks are from the Ural Moun tarns. A corundum anorthosite analogous to kyschtymite has been described by W. G. Miller 2 from Canada ; and corundum-bearing nepheline syenites, according to A. P. Coleman, 3 are also found in the same region. In the Coimbatore district, Madras Presidency, India, T. H. Holland 4 found large crystals of corundum in an albite-orthoclase rock near its contact with elseolite syenite. They were associated with chrysoberyl and zinc spinel, zinc oxide and glucina having here played the part usually assigned to magnesia in the commoner magmas. In the Bid- well Bar quadrangle, California, A. C. Lawson 5 found a dike of an oligoclase-corundum rock cutting peridotite. The solubility of alumina in peridotite magmas — that is, in mag- mas free from lime and alkalies — seems not to have been experimen- tally investigated. The corundum of North Carolina and Georgia, however,' is associated with rocks of this class, and whether it was derived by fractional crystallization from the olivine rock, dunite, or from contact action with adjacent gneisses is an open question. The latter view, which is that of the earlier writers upon these locali- ties, was advocated by T. M. Chatard, 6 but J. H. Pratt 7 argues in favor of a pyrogenic origin. According to Pratt, the corundum crystallized from the fused dunite along the cooler surfaces of con- tact with the surrounding rocks. In these deposits spinel occurs but rarely. The corundum, emery, and iron spinel of the “Cortlandt 1 Min. pet. Mitt., vol. 18, 1898, pp. 212, 219. For present purposes the minor accessory minerals in these rocks may be ignored. 2 Am. Geologist, vol. 24, 1899, p. 276. 3 Jour. Geology, vol. 7, 1899, p. 437. A syenite from Montana, containing 31 per cent of corundum has been described by A. F. Rogers, Jour. Geology, vol. 19, 1911, p. 748. * Mem. Geol. Survey India, vol. 30, 1901, pp. 201, 205. For Indian corundum in general, see Holland, Manual of geology of India, Economic geology, pt. 1; F. R. Mallet, Rec. Geol. Survey India, vol. 5, 1872, p. 20; vol. 6, 1873, p. 43; and C. S. Middlemiss, idem, vol. 29, 1896, p. 39. Mallet describes beds of corundum in gneiss. A remarkable corundum rock from India is described by J. W. Judd in Mineralog. Mag., voL 11, 1895, p. 56. For Burmese occurrences, see C. B. Brown and Judd, Proc. Roy. Soc., vol. 57, 1895, p. 387. On the corundum granulite of Waldheim, Saxony, see E. Kalkowsky, Abhandl. Naturwiss. Gesell. Isis, July-Dee., 1907, p. 47. 5 Bull. Dept. Geology Univ. California, vol. 3, 1903, p. 219. 6 Bull. U. S. Geol. Survey No. 42, 1887, p. 45. Chatard gives abundant references to literature. See also F. P. King’s report upon Georgia corundum (Bull. Geol. Survey Georgia No. 2, 1894), which contains a bibliography of American publications upon the subject. A similar publication by J. V. Lewis, on North Carolina corundum, forms Bull. No. 11 of the North Carolina Geol. Survey, 1896. Vol. 1 of the North Caro- lina Geol. Survey, 1905, by Pratt and Lewis, is a valuable monograph on corundum and chromite. 7 Am. Jour. Sci., 4th ser., vol. 6, 1898, p. 49; vol. 8, 1899, p. 227. In Mineralog. Mag., vol. 12, 1899, p. 139, J. W. Judd and W. E. Hidden have a paper upon North Carolina ruby; also in Am. Jour. Sci., 4th ser vol. 8, 1899, p. 370. 340 THE DATA OE GEOCHEMISTRY. series” in New York were regarded by G. H. Williams 1 as segre- gations in norite. 2 At Yogo Gulch, in the Little Belt Mountains of Montana, corun- dum is found in dikes of lamprophyre which contains too little alumina to satisfy the conditions laid down by Morozewicz. The occurrence has been carefully studied by W. H. Weed 3 and L. Y. Pirsson, 4 who believe that the corundum was not in this case a con- stituent of the original magma, but that is has been produced by the action of the latter upon inclosed fragments of clay shale or lime- stone. This, of course, is a sort of contact action, but its mechanism is not clearly worked out. The thermal decomposition of minerals, especially of silicates, has so far been inadequately studied. Under what neutral conditions can alumina be liberated from its silicates ? This is a question which demands investigation, but it may be noted here that Vernadsky, 5 by fusing muscovite, obtained sillimanite and corundum. Natural corundum evidently may originate in more than one way, and no single process can account for all of its occur- rences. Notwithstanding the fact that corundum is one of the most refrac- tory of minerals toward aqueous solvents, being insoluble in even the strongest acids, it is not absolutely unalterable by them. S. J. Thugutt 6 found that corundum, upon prolonged heating with water to about 230° in a platinum digester, became appreciably hydrated. The product of the reaction after 336 hours contained 5.14 per cent of combined water. Even at 100° in an open vessel, some hydration occurred. A similar prolonged treatment of corundum with a solu- tion of the silicate K 2 Si 2 0 5 converted it into a substance having the composition of orthoclase, while sodium silicate produced a com- pound resembling analcite. In nature reactions of this kind are conceivably possible, but they must be very slow; in the laboratory the acceleration due to temperature and pressure accounts for much of the change. However, alterations of corundum are common, and Thugutt’s experiments give us some notion of the way in which they were probably effected. By water alone corundum may be trans- formed into diasp ore, HA10 2 , which is one of its frequent associates. By further or coincident action of salts dissolved in percolating waters the alteration of corundum can be modified, and a consider- 1 Am. Jour. Sci., 3d ser., vol. 33, 1887, p. 194. 2 For an account of the emery mine at Chester, Massachusetts, see B. K. Emerson, Mon. U. S. Geol. Sur- vey, vol. 29, 1898, p. 117. In Bull. U. S. Geol. Survey No. 269, 1906, J. H. Pratt gives a very complete account of the corundum and emery of the United States, together with much information upon foreign localities. For the emery of Naxos, see S. A. Papavasiliu, Geol. Centralbl., vol. 8, 1905, p. 99. 3 Twentieth Ann. Kept., U. S. Geol. Survey, pt. 3, 1900, p. 454. 4 Idem, p. 552; Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 421. See also G. F. Kunz, Am. Jour. Sci., 4th ser., vol. 4, 1887, p. 417. 6 Cited by Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 25. 6 Mineralchemische Studien, Dorpat, 1891, p. 104. BOCK-FORMING MINERALS. 341 able number of other minerals may be produced. 1 Among them gibbsite, spinel, sillimanite, kyanite, andalusite, pyrophyllite, musco- vite, paragonite, chloritoid, margarite, zoisite, feldspars, tourmaline, and various vermiculites and chlorites have been recorded. 2 Some of these reported alteration products are doubtless secondary and not due to the direct transformation of corundum, but on this subject there is much uncertainty. The envelopment of one mineral by another does not necessarily establish the derivation of the second from the first. The field observations and the study of natural speci- mens need to be reenforced by experiments in the laboratory before accurate conclusions concerning the alterations can be drawn. THE SPINELS. Spinel. — Isometric. Composition, MgAl 2 0 4 . Molecular weight, 142.5. Specific gravity, 3.5. Molecular volume, 40.7. Usually colored violet, green, or red by impurities. Ha/dness, 8. Hercynite. — Isometric. Composition, FeAl 2 0 4 . Molecular weight, 174.1. Specific gravity, 3.93. Molecular volume, 44.3. Color, black. Hardness, 7.5 to 8. These minerals, together with gahnite, ZnAl 2 0 4 , magnetite, Fe // Fe' // 2 0 4 , magnesioferrite, MgFe 2 0 4 , franklinite, and chromite, form a natural isometric group, in which there are many intermediate mixtures. In the general formula R"R'" 2 0 4 , R" may be mag- nesium, ferrous iron, zinc, or manganese; and R'" is represented by aluminum, ferric iron, trivalent manganese, and chromium. In pleonaste we have an intermediate magnesium iron spinel, and in picotite chromium appears. Structurally the formula of spinel is commonly written 0 = A1 — O — Mg — O— A1 = 0, but this should not be taken as a finality. It is not the only expression possible, nor has its validity been proved. 1 For a discussion of the reactions which are supposed to produce the alterations of corundum, see C. R. Van Hise, Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 223-225. 2 F. A. Genth, Proc. Am. Philos. Soc., vol. 13, 1873, p. 361; voL 20, 1882, p. 381; Am. Jour. Sci., 3d ser., vol. 39. 1890, p. 47. These papers are full of details regarding alteration products of corundum. 842 THE DATA OF GEOCHEMISTRY. The following analyses of spinels show the wide variations in their composition: Analyses of spinels. A. Rose spinel, Ceylon. Analysis by H. Abich. B . From V esuvius. Analysis by H. Abich. Analyses A and B cited from Dana’s System of mineralogy, 6th ed., p. 222. C. From lherzolite, Auvergne. Analysis by F. Pisani, Compt. Rend., vol. 63, 1866, p. 49. D. From pyroxenite, Montana. Analysis by L. G. Eakins, Bull. U. S. Geol. Survey No. 220, 1903, p. 20. E. Pleonaste from near Peekskill, New York. Analysis by C. A. Wolle, Am. Jour. Sci., 2d ser., vol. 48, 1869, p. 350. F. Hercynite from the Bohmerwald. Analysis by B. Quadrat, Liebig’s Annalen, vol. 55, 1845, p. 357, A B C D E F ALO, 69. 01 1. 10 67. 46 59. 06 62. 09 2. 62 2. 10 17. 56 Trace. 15. 61 .16 .55 60. 79 61.17 OoO, Fe 2 0 3 10. 72 13. 60 5. 26 21. 74 FeO .71 5. 06 35. 67 MnO MgO 26. 31 25. 94 17. 20 12. 84 2. 92 CaO Si0 2 2.02 2. 38 99. 05 100. 84 100. 58 100. 69 100. 63 99. 76 Members of the spinel group have been made artificially by methods which generally recall those mentioned under corundum. For example,. S. Meunier 1 fused a mixture of alumina, magnesia, cryolite, and aluminum chloride, and obtained spinel crystals. In another investigation 2 he produced them by heating aluminum chloride and water with metallic magnesium in a sealed tube. These processes, with others which have been described, may perhaps repre- sent in a broad way the pneumatolytic methods of nature. The pro- duction of spinel'by the fusion of appropriate magmatic mixtures is, however, the process of greatest importance geologically, and some of the conditions attending its formation have been already described under corundum. E. S. Shepherd and G. A. Rankin 3 have pre- pared spinel by direct fusion of its constituent oxides. The details of Morozewicz’s experiments need not be repeated here . 4 * An inter- esting emphasis is given to them by the observations of G. Linck , 6 who found, in a German gabbro, spinel associated with sillimanite and corundum . 6 Spinels are also formed by the breaking down of other minerals, or by the reactions of two or more species upon one another. Accord- 1 Compt. Rend., vol. 104, 1887, p. 1111. 2 Idem, vol. 90, 1880, p. 701. » Am. Jour. Sci., 4th ser., vol. 28,^909, p. 293. * See also J. H. L. Vogt, Mineralbildung in Schmelzmassen, pp. 189-203. 6 Sitzungsb. X. Akad. Wiss. Berlin, 1893, p. 47. e See also W. Salomon, Zeitschr. Deutsch. geol. Gesell. , vol. 42, 1890, p. 525, for spinel In cordierlte contact rocks In Itaij. ROCK-FORMING MINERALS, 343 ing to Vernadsky, 1 spinel is among the compounds produced by the fusion of biotite, an observation which has been confirmed by C. Doelter. 2 F. W. Clarke and E. A. Schneider 3 found it to be formed when clinochlore and xanthophyllite were strongly ignited, and Doelter 2 also obtained it by fusing the first-named species. Tourmaline, pyrope, and spessartite also yield spinel among the products of their fusion. 4 According to Fouque and Levy 5 spinel and melanite are formed when nephelite and augite are fused together, and Doelter and Hussak 6 obtained spinel from a mixture of fayalite and sarcolite. M. Vucnik 7 found that a mixture of magnetite and anorthite gave recrystallized anorthite, hercynite, and glass, the magnetite having disappeared. Similar observations with augite-elseolite and corun- dum-elseolite mixtures were made by B. Vukits. 8 Spinel, especially pleonaste, is a common accessory mineral in gneisses and in many eruptive rocks. Picotite is more character- istic of the peridotites and the derived serpentines. Spinel is a frequent companion of corundum and also of emery, as at Chester, Mass., and in the norite at Crugers, N. Y. 9 A number of remarkable spinel rocks from Elba have been described by P. Aloisi. 10 A troc- tolite from Madagascar, rich in spinel, is reported by A. Lacroix. 11 Many of these occurrences are easily interpreted in the light of Morozewicz’s experiments. The other experiments, cited above, explain the appearance of spinel as a contact mineral. In many cases it appears in limestones as a product of contact metamorphism. Its alterations seem to have been little studied, but a change into steatite is mentioned in the literature. Chromite. — Isometric. Normal composition, FeCr 2 0 4 , but with variable replacements of Fe" by Mg and of Cr by Al and Fe'", as in the other 'members of the spinel group. Specific gravity, 4.32 to 4.57. Color, black. Hardness, 5.5. The following analyses are fairly typical : 12 1 Cited by J. Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 59. 2 Neues Jahrb., 1897, Band 1, p. 1. s BuU. U. S. Geol. Suivey No. 113, 1893, p. 30. * Doelter, loe. cit., for tourmaline. C. Doelter and E. Hussak, Neues Jahrb., 1884, Bandl,p. 157, for garnets. 6 Synth&se des min6raux et des roches, p. 64. 6 Neues Jahrb., 1884, Band 1, p. 157. 7 Centralbl. Min., Geol. u. Pal., 1904, p. 297. Criticized by J. Morozewicz in the same journal, 1905, p. 148. s Idem, 1904, pp. 710, 743. » G. H. Williams, Am. Jour. Sci., 3d ser., vol. 33, 1887, p. 194. See also J. n. Pratt, Bull. U. S. Geol. Survey No. 2C9, 1906, p. 34. Proc. verb. Soc. tosc. sci. nat., vol. 15, p. 60. 11 Bull. Soc. min., vol. 31, 1908, p. 318. 12 A very complete collection of chromite analyses , down to 1884 , with literature references , is given in M. E. Wadsworth’s Lithological studies: Mem. Mus. Comp. Zool. Harvard Coll., vol. 11, 1884. A mineral from Serbia, of composition Fe 20 s.Cr 203 , has been named chromitite by M. Z. Jovitschitsch, Monatsh. Chemie, vol. 30, 1909, p. 39. Also, later, Bull. Soc. Min., vol. 35, 1911, p. 511. 844 THE DATA OF GEOCHEMISTRY. Analyses of chromite. A. From vicinity of Mundorff, British Columbia. Chrompicotite. Analysis by R. A. A. Johnston, for G. C. Hoffmann, Am. Jour. Sci., 4th ser., vol. 13, 1902, p. 242. B. From Corundum Hill, North Carolina. Analysis by C. Baskerville, for J. H. Pratt, Am. Jour. Sci., 4th ser., vol. 7, 1899, p. 281. C. From Webster, North Carolina. Analysis by H. W. Foote, for Pratt, loc. cit. D. From Port au Port Bay, Newfoundland. Analysis by E. Waller, for G. W. Maynard, Trans. Am. nst. Min. Eng., vol. 27, 1897, p. 283. E. From Tampadal, lower Silesia. Analysis by Laszczynski, for H. Traube, Zeitschr. Deutsch. geol. Gesell., vol. 46, 1894, p. 60. A B C Do E Cr 9 0o 55. 90 57. 80 39. 95 49. 23 41. 23 AloOq 13. 83 7. 82 29.28 7. 50 24. 58 Fe 2 0 3 2. 28 FeO 14.64 25. 68 13. 90 17. 21 16. 99 MnO . 69 Trace. .58 MgO 15. 01 5. 22 17. 31 18. 66 14. 77 Si0 2 .60 2. 80 6. 51 99. 98 100. 01 100. 44 99. 11 100. 43 oAlso contains traces of lime, copper, and vanadium. The earlier syntheses of chromite seem to have little or no geo- logical bearing. S. Meunier, 1 however, who prepared chromite by oxidizing an alloy of iron and chromium, attributes its origin to a similar reaction occurring in nature. He supposes that such an alloy, like platinum and nickel iron, can be brought up from the interior of the earth to be oxidized by vapors when it nears the surface. Unfortunately, no such alloy has yet been found in the rocks, and in meteorites chromite itself is a common mineral. Chromite is essentially a constituent of peridotites and of the serpentines derived from them. It is one of the earliest species formed during the solidification of the magma, and its larger deposits, when it occurs in ore bodies, are now generally ascribed to magmatic differentiation through the action of gravity. J. H. L. Vogt 2 thus interprets the chromite deposits of Norway, and J. H. Pratt 3 has elaborated the same conception with respect to the chromic iron ores of North Carolina. The origin of corundum and of chromite in dunite Pratt explains in the same way. When a peridotite alters to serpentine, the refractory chromite remains unchanged. Magnetite. — Isometric. Composition, Fe 3 0 4 , but with variable impurities and replacements. Molecular weight, 231.7. Specific gravity, 5.17. Molecular volume, 44.8. Color, black. Hardness, 5.5 to 6.5. Magnesium, manganese, aluminum, and titanium are common impurities, rutile, ilmenite, hematite, and the spinels being 1 Compt. Rend., vol. 110, 1890, p. 424. 2 Zeitschr. prakt. Geologie, 1894, p. 384. s Trans. Am. Inst. Min. Eng., vol. 29, 1899, p. 17. For a general review of chromite deposits, see Stelzner- Bergeat, Die Erzlagerstatten, 1904, p. 33. The magmatic view is adopted in this work and also in Beck’s treatise upon ore bodies. ROCK-FORMING MINERALS. 845 frequent admixtures in magnetite. The titaniferous magnetites form a well-known subclass of ores. In a magnetite from the Tyro- lese Alps, T. Petersen 1 found 1.76 per cent of nickel oxide, and the magnetites of eastern Ontario may contain half as much. 2 Magnetite is often observed as a furnace product, and it forms the “iron scale” of the blacksmith. W. Miiller 3 found both magnetite and hematite in crystals among the oxidation products of the iron- bearing residues from an aniline factory. The mineral has also been produced artificially by several investigators. J. J. Ebelmen 4 pre- pared it, well crystallized, by fusing together an iron silicate and lime. According to H. Sainte-Claire Deville, 5 ferrous oxide, heated in a stream of hydrochloric acid, forms magnetite, while a mixture of magnesia and ferric oxide, similarly treated, yields magnesiofer- rite, MgFe 2 0 4 . T. Sidot 6 obtained magnetite by the calcination of ferric oxide alone. In artificial magmas magnetite is easily formed, especially when the proportion of silica is low. Any excess of iron over that needed to combine with silica is likely to be deposited in the form of mag- netite, although the conditions of its appearance are not so simple as in the separation of alumina as corundum. 7 The order of its crystallization with reference to other minerals is by no means invariable. Like the spinels, magnetite may be formed by the breaking down of other species, or by reactions between them. In other words, it may be a product of contact metamorphism. C. Doelter, 8 for ex- ample, repeatedly obtained it by fusing various rocks in contact with limestone — a procedure which recalls Ebelmen’s experiment. Ac- mite upon fusion yields magnetite and a glass, 9 and glaucophane gives similarly a mixture in which magnetite appears. By melting together biotite and microcline, Fouqu6 and Levy 10 obtained magne- tite, leucite, and olivine. J. Lenarcic 11 found magnetite in the mass produced by fusing leucite with augite; but on the other hand, when magnetite and labradorite were taken, the former mineral was dis- solved and augite appeared. Similar observations were made by M. Vucnik 12 and B. Vukits, 13 who found magnetite among the fusion 1 Neues Jahrb., 1867, p. 836. 2 W. G. Miller, Rept. British Assoc., 1897, p. 600. 3 Zeitschr. Deutsch. geol. Gesell., vol. 45, 1893, p. 63. 4 Compt. Rend., vol. 33, 1851, p. 528. * Idem, vol. 53, 1861, p. 199. 6 Idem, vol. 69, 1869, p. 201. 7 See J. Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 84, and J. ET. L. Vogt, Minsralbildung in Schmelz- massen, pp. 203-212. s Neues Jahrb., 1886, Band 1, p. 128. » Doelter, Neues Jahrb. 1897, Band 1, p. 1. See also M. Vutaik, cited below, w Synthase des mindraux et des roches, p. 77. u Centralbl, Min., Geol u. Pal., 1903, pp. 705, 743. 12 Idem, 1904, pp. 300, 342, 344, 345, 366, 369. 18 Idem, 1904, pp. 705, 715, 743, 748. 846 THE DATA OF GEOCHEMISTRY. products of anorthite and hedenbergite, albite and hedenbergite, olivine and augite, elseolite and augite, and ebeolite and diopside. Each of these couples, when fused, yielded magnetite, with other products which varied according to the nature of the mixture. Magnetite occurs as an accessory mineral in rocks of all classes, and it sometimes rises to the rank of a principal constituent, or even forms rock masses by itself. It is obviously most abundant in rocks rich in ferromagnesian minerals, such as norites, diabases, gabbro3, or peridotites; but it i3 also associated with nepheline rocks and anorthites. In many cases it forms large ore bodies that are regarded as products of magmatic differentiation; and these deposits, as a rule, are highly titaniferous. 1 Some ores shade from magnetite into ilmenite, with over 40 per cent of titanic oxide. They frequently contain spinel, and sometimes, also, corundum. In the great iron deposits of the Lake Superior region, and the adjacent parts of Michigan, Wisconsin, and Minnesota, magnetite is found in slates and cherts, often associated with grunerite and actino- lite. 2 Here the mineral is not of direct igneous origin. In the Mesabi district, according to C. K. Leith, 3 it is derived from the leaching of a hydrous iron silicate, of uncertain composition, to which he has given the name “greenalite.” Other silicates may yield magnetite through metamorphic changes, and it can also form, says C. It. Van Hise, 4 from marcasite and pyrite, and from the oxidation of siderite in place. By further oxidation magnetite can alter to hematite and limonite, and through the agency of carbonated waters it may be transformed into siderite again. HEMATITE. Rhombohedral. Composition, Fe 2 0 3 . Molecular weight, 159.8. Specific gravity, 5.2. Molecular volume, 30.7. Color, red to steel- gray and black. Hardness, 5.5 to 6.5. Hematite has been prepared artificially by several methods. In the classical experiment of Gay-Lussac, 5 the vapor of ferric chloride was decomposed by steam at a high temperature, and crystals of hematite were formed. A. 1 See J. H. L. Vogt, Zeitschr. prakt. Geologie, 1893, p. 6; 1894, p. 382; 1900, pp. 234, 370; 1901, pp. 9, 180, 289, 327. J. F. Kemp, Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1899, p. 377; School of Mines Quart., vol. 20, 1899, p. 323; vol. 21, 1900, p. 5G; Zeitschr. prakt. Geologie, 1905, p. 71. W. Lindgren, Science, vol. 16, 1902, p. 984. G. H. Williams, Am. Jour. Sci., 3d ser., vol. 33, 1887, p. 194. R. Beck, Lehre von den Erzlagerstatten, 2d ed., pp. 20-30. Kemp’s paper in the School of Mines Quarterly is a general review of the titaniferous magnetites, with many analyses and copious references to other literature. In Zeitschr. prakt. Geologie, 1907, p. 86, Vogt describes magmatic iron ores in granite. On magmatic iron ores in U tah, see E. P. Jennings, Trans. Am. Inst. Min. Eng., vol. 35, 1905, p. 338. On the magmatic magnetites of Lapland, see O. Stutzer, Neues Jahrb., Beil. Band 24, 1907, p. 548. A magnetite basalt from Colorado is described by II. S. Washington and E. S. Larsen in Jour. Washington Acad. Sci., vol. 3, 1913, p. 449. 2 See C. R. Van Hise, W. S. Bayley, II. L. Smyth, and J. M. Clements, in Mon. U. S. Geol. Survey, vol. 28, 1897; vol. 36, 1889; and vol. 45, 1903. 3 Mon. U. S. Geol. Survey, vol. 43, 1903, pp. 101-115. 4 A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, p. 229. 6 See R. Brauns, Chemische Mineralogie, 1896, p. 231. ROCK-FORMING MINERALS. 347 DaubrSe 1 obtained it by passing ferric chloride vapor over lime; and H. Sainte-Claire Deville 2 prepared the specular variety by the slow action of gaseous hydrochloric acid upon ferric oxide at a red heat. Hematite is also produced, according to H. Arctowski, 3 by the action of vaporized ammonium chloride upon either red-hot iron or ferric oxide. It has also been noted as a sublimation product in the salt- cake furnaces of certain chemical works. 4 * Fine crystals of hematite, grouped in rosettes, have been formed in the iron heating pipes of a Deacon chlorine apparatus in Philadelphia. Some of the crystals were as much as 3 centimeters in diameter. Their formation was due to the action of heated air and hydrochloric acid upon the iron. Ferric chloride was probably first formed and then transformed into hematite by aqueous vapor. All these reactions are analogous to, if not identical with, those that produce the so-called “sublimed” hematite which is seen upon volcanic lavas. A. Arzruni, 6 on com- paring the volcanic mineral with the artificial product, found them to be crystallographically identical. W. Bruhns's experiment, 7 in which hematite was formed by heating amorphous ferric oxide with water and a trace of ammonium fluoride to 300° in a platinum tube, seems to be less closely related to geological phenomena. Fouque and Levy 8 repeatedly obtained hematite from artificial magmas, and similar observations have been made by others. In ordinary furnace slags, however, according to J. H. L. Vogt, 9 hema- tite rarely if ever occurs. Ferric oxide can crystallize out as hematite only when ferrous compounds are either absent or present in quite subordinate amounts, for ferrous oxide unites with it to form mag- netite. The latter species, therefore, is characteristic of rocks rich in ferromagnesian minerals, while hematite appears chiefly in the more siliceous and feldspathic granites, syenites, trachytes, rhyolites, andesites, and phonolites. It is also found in the crystalline schists; but magnetite is by far the more common as a pyrogenic mineral. In igneous rocks generally ferrous oxide exceeds the ferric in amount, the average percentages, as shown by 961 analyses, 10 being 3.46 FeO and 2.63 Fe 2 0 3 . This preponderance of the lower oxide seems to determine the frequent formation of magnetite. The ferric pyrite and the ferrous pyrrhotite appear to follow the same rule of association, 1 Compt. Rend., vol. 39, 1854, p. 135. 2 Idem, vol. 52, 1861, p. 1264. s Zeitschr. anorg. Chemie, vol. 6, 1894, p. 377; Bull. Acad. roy. sci. Belgique, 3d ser., vol. 27, 1894, p. 933. < See H. Vater, Zeitschr. Kryst. Min., vol. 10, 1885, p. 391; and B. Doss, idem, vol. 20, 1892, p. 566. 6 C. E. Munroe, Am. Jour. Sci., 4th ser., vol. 24, 1907, p. 485. Zeitschr. Kryst. Min., vol. 18, 1891, p. 46. 1 Neues Jahrb., 1889, Band 2, p. 62. 8 Synthase des min6raux et des roches, p. 236. 9 Mineralbildung in Schmelzmassen, pp. 215-217. Cf. also J. Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 84. 19 Bull. U. S. Geol. Survey No. 228, 1904, p. 17. 348 THE DATA OF GEOCHEMISTRY. the one being commonest in highly silicic rocks, the other accom- panying the ferromagnesian minerals. Hematite alters into limonite, magnetite, pyrite, marcasite, and siderite , 1 and in metamorphic rocks it may be derived from the same species. Limonite, siderite, and magnetite are especially liable to yield it. The derivation of hematite from silicates is probably always indirect, one or another of the above-named species having been formed first. Titanium is a common impurity in hematite, and L. J. Igelstrom , 2 in a Swedish ore, found molybdenum in very appreciable amounts. TITANIUM MINERALS. Tlmenite. — Rhombohedral. Composition, FeTi0 3 . Molecular weight, 152. Specific gravity, 4.5 to 5. Molecular volume, 30.4. Color, black; luster, submetallic. Hardness, 5 to 6. Ilmenite, menaccanite, or titanic iron has been little investigated upon the synthetic side. W. Bruhns 3 prepared it, mixed with some magnetite, by heating finely divided metallic iron, ferric oxide, and amorphous titanic oxide with hydrochloric acid in a platinum tube to 270-300°. In nature, however, it is found most widely diffused. It occurs with or replacing hematite in granite and syenites and as an essential constituent in diorite, diabase, gabbro, basalt, etc., often with magnetite. 4 In these rocks it is one of the earliest minerals to separate. It i3 also found in metamorphic rocks, such as gneiss, mica schist, and amphibolite. A. von Lasaulx 5 describes ilmenite as an alteration derivative of rutile. The constitution of ilmenite has been much discussed. Some au- thorities have regarded it as an isomorphous mixture of Fe 2 0 3 and Ti 2 0 3 ; but C. Friedel and J. Guerin, 6 who prepared the latter com- pound artificially, do not favor this view. Ti 2 0 3 as such has not been found as an independent mineral. T. Konig and O. von der Pfordten 7 made various attempts to detect Ti 2 0 3 in ilmenite and only met with failure. Since the mineral pyrophanite, MnTi0 3 , isomorphous with ilmenite, is known, and since, as S. L. Penfield and H. W. Foote 8 have shown, ilmenite sometimes contains large admixtures of the molecule MgTiO s , the formula FeTiO s may now be regarded as estab- lished for titanic iron. In an ilmenite from Warwick, New York, Penfield and Foote found 16 per cent of magnesia. In fact, the com- 1 C. R. Van Hise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, p. 226. 2 Zeitschr. Kryst. Min., vol. 25, 1896, p. 94. 8 Neues Jahrb., 1889, Band 2, p. 65. 4 See the papers of Vogt, Kemp, and others cited under magnetite. The titaniferous magnetites are mixtures of that species with ilmenite. See also A. Cathrein, Zeitschr. Kryst. Min., vol. 8, 1884, p. 321. Urbainite is a rock rich in ilmenite found at St. Urbain, Canada. Described by C. H. Warren, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 263. 4 Zeitschr. Kryst. Min., vol. 8, 1884, p. 54. 8 Annales chim. phys., 5th ser., vol. 8, 1876, p. 38. r Ber. Deutsch. chem. Gesell., vol. 22, 1889, p. 1485. See also W. Manchot, Zeitschr.anorg. Chemie, vol. 74, 1912, p. 79. 8 Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 108. ROCK-FORMING MINERALS. 549 pound MgTiO a is independently represented by the mineral geikie- lite 1 from Ceylon. An excess of iron in ilmenite may be due to admixed hematite and an excess of titanium to rutile. Ilmenite is often surrounded by a margin of white or even reddish alteration products, which is commonly known by the name of leu- coxene. According to A. Cathrein, 2 this substance is essentially titanite, sometimes accompanied by rutile. Pseudobrookite. — Orthorhombic. Composition, ferric orthotitan- ate, Fe 4 (Ti0 4 ) 3 . Molecular weight, 559.9. Specific gravity, 4.39. Molecular volume, 127.5. Color, dark brown to black. Hardness, 6. Pseudobrookite is a rare accessory mineral in certain eruptive rocks, such as andesite, trachyte, basalt, and nephelinite. A similar mineral, formed by “sublimation” in a salt-cake furnace, was de- scribed by B. Doss, 3 who gave it the formula Fe 2 Ti0 5 and made it isomorphous with andalusite, Al 2 Si0 5 . The natural mineral, however, has the orthotitanate formula, as given above. 4 Perofskite. — Isometric or pseudoisometric. Composition, calcium titanate, CaTi0 3 . Molecular weight, 136.2. Specific gravity, 4. Molecular volume, 34. Color, yellow, ranging through orange and brown to grayish black. Hardness, 5.5. Perofskite has been prepared synthetically by several chemists. J. J. Ebelmen 5 obtained it by fusing titanic oxide with lime and potassium carbonate; and later 6 by the action of lime on an alkaline melt containing titanic oxide and silica. P. Hautefeuille 7 heated a mixture of calcium chloride, titanic oxide, and silica to redness in a stream of moist carbon dioxide, or of hydrochloric acid, and obtained perofskite crystals. L. Bourgeois 8 observed its deposition from various fused mixtures resembling natural magmas in composition. Finally, P. J. Holmquist 9 prepared perofskite by fusing together sodium carbonate, calcium carbonate, and titanic oxide, under special manipulative conditions. Perofskite occurs both in eruptive and metamorphic rocks. It is found in melilite, leucite, and nepheline rocks, and in some perido- tites; 10 and is among the earliest secretions. It is particularly charac- teristic of melilite basalt, being, according to A. Stelzner, 11 the most faithful companion of melilite. At Catalao, Brazil, E» Hussak 12 found 1 A description of geikielite by T. Crook and B . M. Jones is printed in Mineralog. Mag. , vol. 14, 1906, p. 160. 2 Zeitschr. Kryst. Min., vol. 6, 1882, p. 244. 3 Idem, vol. 20, 1892, p. 566. Doss gives a good bibliography of pseudobrookite. 4 Established by A. Frenzel, Min. pet. Mitt., vol. 14, p. 121; confirming the earlier analyses of A. Koch, G. Lattermann, and A. Cedarstrom. See E. S. Dana, System of mineralogy, 6th ed., p. 232. 6 Compt. Rend., vol. 32, 1851, p. 710. e Idem, vol. 33, 1851, p. 528. 7 Annales chim. phys., 4th ser., vol. 4, 1865, p. 163. 8 Idem, 5th ser., vol. 29, 1883, p. 479. 0 Bull. Geol. Inst. Upsala, vol. 3, 1896-97, p. 181. 10 See G. H. Williams, Am. Jour. Sci.,3d ser., vol. 34, 1887, p. 137; J. S. Diller, ldem,vol.37, 1889, p. 219. u Neues Jahrb., Beil. Band 2, 1883, p. 390. 12 Neues Jahrb., 1894, Band 2, p. 297. 350 THE DATA OF GEOCHEMISTRY. a peculiar rock consisting of magnetite and perofskite; a titaniferous magnetite of a new kind. A similar rock has been found in the Un- compahgre quadrangle by E. S. Larsen and analyzed in the labora- tory of the United States Geological Survey. Perofskite is also found in chlorite schist, limestone, quartz gneiss, 1 etc. Hussak observed its alteration into titanic oxide, and K. Schneider 2 has described perof- skite as derived from titanite. Titanite, — Monoclinic. Composition, CaTiSi0 5 . Molecular weight, 196.5. Specific gravity, 3.54. Molecular volume, 55.5. Color, yel- low, green, red, gray, brown, or black. Hardness, 5 to 5.5. Titanite, or sphene, has been produced artificially by several experi- menters, but it does not seem to be easily formed. P. Hautefeuille 3 prepared it by fusing a mixture of silica and titanic oxide with cal- cium chloride. L. Bourgeois 4 obtained it, but obscurely developed, by fusing together its constituent oxides, silica, titanic oxide, and lime. L. Michel 5 fused ilmenite with calcium sulphide, silica, and carbon, which yielded a mixture of titanite, garnet, and a subsulphide of iron. S. Smolensky 6 prepared titanite by Bourgeois’s method and determined its melting point as 1,221°. As a pyrogenic mineral titanite is found among the oldest secre- tions in the more siliceous rocks, such as granites, diorites, syenites, and trachyte. It is abundant in phonolites and elaeolite syenites, and is also common as a secondary mineral, derived by alteration from rutile or ilmenite. It is often associated with chlorite. At Green River, North Carolina, large crystals of sphene are found com- pletely or partially altered into a yellow, friable, earthy substance which has been given the name of xanthitane. According to L. G. Eakins, 7 this product is a hydrous titanate of aluminum. An altera- tion of titanite into rutile has been observed by P. Mann 8 in the foyaite of the Serra de Monchi que; and B. Doss 9 has reported pseudo- morphs of anatase after sphene. Rutile. — Tetragonal. Composition, Ti0 2 . Molecular weight, 80.1. Specific gravity, 4.2. Molecular volume, 19.1. Color, commonly red- dish to brown or black. Plardness, 6 to 6.5. Broolnte. — Orthorhombic. Composition and molecular weight as for rutile. Specific gravity, 4. Molecular volume, 20. Color, yel- lowish, reddish, brown, or iron-black. Hardness, 5.5 to 6. Octdhedrite or anatase. — Tetragonal. Composition and molecular weight the same as for rutile and brookite. Specific gravity, 3.82 to 1 See O. Miigge, Neues Jahrb., Beil. Band 4, 1886, p. 581. 2 Neues Jahrb., 1889, Band 1, p. 99. * Annales chim. phys., 4th ser., vol. 4, 1865, p. 129. * Idem, 5th ser., vol. 29, 1883, p. 474. * Compt. Rend., vol. 115, 1892, p. 830. 8 Zeitschr. anorg. Chemle, vol. 73, 1912, p. 302. 2 Bull. U. S. Geol. Survey No. 60, 1890, p. 135. 8 Neues Jahrb., 1882, Band 2, p. 200. 9 Idem, 1895, Band 1, p. 128. ROCK-FORMING MINERALS. 351 3.95. Molecular volume, 20.5. Color, brown, indigo-blue, and black. Hardness, 5.5 to 6. All three modifications of titanic oxido have been studied synthet- ically. Crystals of brookite were obtained by A. Daubree, 1 by the action of aqueous vapor upon titanic chloride at a red heat. By heating amorphous titanic oxide to redness in a current of hydro- chloric acid gas, H. Sainte-Claire Deville and H. Caron 2 transformed it into a crystalline modification, and similar results were obtained by P. Hautefeuille and A. Pcrrey. 3 By the prolonged heating of titanic oxide with boric acid J. J. Ebelmen 4 obtained rutile, and P. Hautefeuille 5 attained the same end when sodium tungstate or vana- date was used as flux. H. Traube 6 also crystallized rutile from fused sodium tungstate, and was able to add to it appreciable quantities of iron, manganese, and chromium, impurities which are found in the natural mineral. Several investigators have prepared rutile by the same general process, using microcosmic salt as the solvent. B. Doss, 7 by this method, prepared both rutile and anatase. Deville and Caron 8 also prepared rutile by heating titanic oxide with silica and oxide of tin to redness. By heating ilmenite and pyrite together at about 1,200°, L. Michel 9 obtained a mixture of rutile and pyrrhotite. The three forms of titanic oxide were reproduced by P. Haute- feuille 10 by various modifications of the same general pneumatolytic process. Potassium titanate and calcium chloride were heated in a current of hydrochloric acid mixed with air, and crystals were formed. Titanic oxide with potassium or calcium fluoride, or potassium silico- fluoride, similarly treated, gave the same products, which, when the operation was conducted at a strong red heat, was rutile. Brookite was formed by heating potassium titano fluoride in aqueous vapor, and by the action of hydrofluoric acid upon titanic chloride, at a temperature not higher than the boiling point of zinc. A mixture of titanic oxide, calcium fluoride, and potassium chloride, heated in a stream of hydrochloric acid, silicon fluoride, and moist hydrogen, also gave brookite, and so did titanic oxide, silica, and potassium silicofluoride in a current of hydrochloric acid alone. When titanic fluoride was decomposed by aqueous vapor at a lower temperature, at or near the boiling point of cadmium, octahedrite was produced. How far these experiments may parallel the pneumatolytic processes of nature is doubtful; but they show that rutile, the most stable 1 Compt. Rend., vol. 29, 1849, p. 227. 8 Idem, vol. 53, 1861, p. 161. 3 Idem, vol. 110, 1890, p. 1038. < Idem, vol. 32, 1851, p. 330. 6 Cited by Bourgeois, Reproduction artiflcielle des min6raux, 1884, p. 85. 8 Neues Jahrb., Beil. Band 10, 1895-96, p. 470. 7 Idem, 1894, Band 2, p. 147. 8 Compt. Rend., vol. 53, 1861, p. 161. 9 Idem, vol. 115, 1892, p. 1020. io Annales chim. phys., 4th ser., vol. 4, 1865, p. 129. 852 THE DATA OF GEOCHEMISTRY. modification of titanic oxide, is formed at the highest temperatures, brookite at temperatures considerably lower, and anatase at a point still lower in the scale. These observations are in harmony with the known occurrences of the three species as rock-forming minerals. Rutile occurs as a pyrogenic mineral in eruptive rocks, but it is more common in gneiss, mica schist, and the phyllites. In a horn- blende gneiss from Freiberg, A. Bergeat 1 observed rutile, ilmenite, and titanite, which had formed as a single generation and crystallized before the biotite. A remarkable dike rock in Nelson County, Vir- ginia, described by T. L. Watson and S. Taber, 2 consists essentially of rutile and apatite. Rutile is also found as a secondary mineral, derived from ilmenite and titanite. C. Doelter 3 found rutile to be slightly soluble in water, and more so in a solution of sodium fluoride. From such a solution after heating to 145° during thirty-four days the mineral was partially recrystallized. Possibly some secondary rutile may originate from solution of the original substance, or of titanic oxide leached from another species. Brookite is not found in fresh eruptive rocks, but generally in decomposed granite, gneiss, quartz porphyry, and the sedimentaries. Octahedrite is never primary, but is formed by the alteration of other titanium minerals. It has been observed under a great variety of conditions, as in granite, diabase, quartz porphyry, diorite, the crys- talline schists, shales, sandsto nes, and limestones. 4 Brookite alters into rutile, and rutile into ilmenite, anatase, and sphene. The titanium minerals are thus closely connected with one another, and transformations are possible in almost every direction. From a magma deficient in lime and iron, titanic oxide may separate as rutile; when lime is abundant, titanite or perofskite may form; in presence of much iron ilmenite or pseudobrookite will be deposited. Brookite and octahedrite appear only as secondary minerals. CASSITERITE AND ZIRCON. Cassiterite. — Tetragonal. Composition, stannic oxide, Sn0 2 . Mo- lecular weight, 151. Specific gravity, 6.9. Molecular volume, 21.9. Color, commonly brown to black, rarely colorless, red, or yellow. Hardness, 6 to 7. A. Daubree 5 prepared cassiterite by the action of aqueous vapor upon tin tetrachloride in a red-hot porcelain tube. H. Sainte-Claire Deville 6 obtained it by passing gaseous hydrochloric acid over the 1 Neues Jahrb., 1895, Band 1, p. 232. 2 Bull. U. S. GeoL Survey No. 430, 1910, p. 200. s Min. pet. Mitt., vol. 11, 1890, p. 325. * For a very full summary of the occurrence of zircon and the titanium minerals, especially brookite and anatase, see H. Thiirach, Verhandl. Phys. med. Gesell. Wlirzburg, vol. 18, No. 10, 1884. On the rutile of Nelson County, Virginia, see G. P. Merrill, Eng. and Min. Jour., March 8, 1902, and T. L. Watson, Eoon. Geology, vol. 2, 1907, p. 493. 6 Compt. Rend., vol. 29, 1849, p. 227. 6 Idem, vol. 63, 1861, p. 101. EOCK-FORMTNG MINERALS. 353 amorphous oxide of tin at a high temperature, and also by acting upon stannous chloride with aqueous vapor. According to A. Ditte, 1 stannic oxide may be crystallized by fusion with calcium chloride; and its crystallization is mentioned by Deville and H. Caron 2 as having been effected by heating a fluoride of tin with boric oxide. The formation of cassiterite as a furnace product has several times been observed, most recently by A. Arzruni 3 and J. H. L. Vogt. 4 In this case it was produced during the manufacture of pulverulent stannic oxide, by the slow oxidation of metallic tin. With this excep- tion, the syntheses of cassiterite point to its origin as a pneumato- lytic mineral, and its commoner associations tell a similar story. It is almost invariably accompanied by minerals containing boric oxide or fluorine, such as topaz, tourmaline, lepidolite, and apatite. 5 Cassiterite is rarely found as an original rock-forming mineral. M. von Miklucho-Maclay 6 has reported it accompanied by rutile, topaz, apatite, and tourmaline, as an inclusion in the mica of a gran- ite. According to R. Beck, 7 it is also an original constituent of granite on the islands of Banca and Billiton. It also occurs, but sparingly, in the lithia-bearing pegmatites of Maine and California, and, according to L. C. Graton, 8 as an original constituent of pegma- tite in the Carolinas. The relations of cassiterite as a vein mineral will be considered in another connection later. Zircon . — Tetragonal. Composition, zirconium orthosilicate, ZrSi0 4 . Molecular weight, 183. Specific gravity, 4.6 to 4.8. Molecular vol- ume, 38.7. Color, commonly brown, but also colorless, yellow, red, bluish, green, etc. Hardness, 7.5. Zircon has been repeatedly produced synthetically. H. Sainte- Claire Deville and H. Caron 9 obtained it by heating zirconia in a current of silicon fluoride. Deville 10 also prepared it by heating zir- conia with quartz in the same gas. In the latter process, which is identical in character with the former, zirconium fluoride is formed, which reacts upon the quartz, regenerating the silicon fluoride. A small quantity of the latter substance may therefore generate an indefinite amount of zircon. P. Hautefeuille and A. Perrey 11 obtained zircon when a mixture of silica, zirconia, and lithium molybdate was 1 Compt. Rend., vol. 96, 1883, p. 701. 2 Idem, vol. 46, 1858, p. 766. s Zeitschr. Kryst. Min., vol. 25, 1896, p. 467. 4 Idem, vol. 31, 1899, p. 279. 3 For a list of tlie minerals occurring with cassiterite, see W. Kohlmann, Zeitschr. Kryst. Min., vol. 24, 1895, p. 350. 6 Neues Jahrb., 1885, Band 2, p. 88. 1 Zeitschr. Kryst. Min., vol. 33, 1900, p. 205. 8 Bull. U. S. Geol. Survey No. 293, 1906. * Compt. Rend., vol. 46, 1858, p. 764. M Idem, vol. 52, 1861, p. 780. ii Idem, vol. 107, 1888, p. 1000. 97270°— Bull. 6i6— 16 23 354 THE DATA OF GEOCHEMISTRY. heated to 800°. Finally, K. Chrustschoff 1 effected the synthesis of zircon by heating gelatinous silica and gelatinous zirconia together, under pressure, to a temperature near redness. Deville’s work indi- cates a possible pneumatolytic origin for zircon in some instances; the other processes seem to be unrelated to the ordinary occurrences of the mineral. Zircon is one of the commonest accessory constituents in all classes of igneous rocks. It is especially common in the more silicic species, such as granite, syenite, diorite, etc., and in all the younger eruptives. It is very characteristic of the nepheline syenites. 2 It is one of the earliest minerals to crystallize from the cooling magmas, and the first one among the silicates. With or in place of zircon some more complex silicates, such as the zircon pyroxenes, may form. These substances, however, are exceedingly rare and quite imperfectly known. PHOSPHATES. Apatite. — Hexagonal. Composition variable, two compounds being included in the species. 3 They are Ca 5 (P0 4 ) 3 F and Ca 5 (P0 4 ) 3 Cl. Molecular weight, 504.5 for fluorapatite and 521 for chlorapatite. Specific gravity, 3.17 to 3.23. Molecular volume, 159.1 to 161.6. Color, white, green, blue, red, yellow, gray, or brown. Hardness, 5. The first synthesis of apatite was effected by A. Daubree, 4 who obtained it in crystals by passing the vapor of phosphorus trichloride over red-hot lime. N. S. Manross 5 fused sodium phosphate either with calcium chloride, calcium fluoride, or both together, and so obtained chlorapatite, fluorapatite, or a mixture of the two, resembling natural apatite, at will. This process, slightly modified, was also adopted by H. Briegleb 6 successfully. G. Forchhammer 7 prepared chlorapatite by fusing calcium phosphate with sodium chloride. When bone ash or marl was used instead of the artificial calcium phos- phate, a mixed apatite was formed. Similar results were reported by Deville and Caron, 8 who fused bone ash with ammonium chloride and either calcium chloride or fluoride, and also by A. Ditte, 9 who repeated Forchhammer’s experiment. By heating calcium phosphate 1 Neues Jahrb., 1892, Band 2, p. 232. 2 For an elaborate discussion of the natural occurrences of zircon, see H. Thiirach, Verhandl. Phys. med. Gesell. Wurzburg, vol. 18, No. 10, 1884. For zircon in the augite syenites of Norway, see W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1890, p. 101. A zirconiferous sandstone found near Ashland, Vir- ginia, has been described by T. L. Watson and F.L. Hess, Bull. Philos. Soc. University of Virginia, vol. 1, 1912, p. 267. 3 For complete analyses of apatite, with a discussion of its variations, see J. A. Voelcker, Ber. Deutsch. chem. Gesell., vol. 16, 1883, p. 2460. For manganese, magnesium, cerium, etc., in apatite, see E. S. Dana, System of mineralogy, 6th ed., pp. 764, 765. * Compt. Rend., vol. 32, 1851, p. 625. 6 Liebig’s Annalen, vol. 82, 1852, p. 353. 6 Idem, vol. 97, 1856, p. 95. 2 Idem, vol. 90, 1854, pp. 77, 322. 8 Compt. Rend., vol. 47, 1858, p. 985. 9 Idem, vol. 94, 1882, p. 1592. ROCK-FORMING MINERALS. 355 with calcium chloride and water, under pressure, at 250°, H. Debray 1 prepared chlorapatite. E. Weinschenk 2 also produced it by heating calcium chloride, ammonium phosphate, and ammonium chloride at temperatures of 150° to 180° in a sealed tube. F. K. Cameron and W. J. McCaughey 3 prepared fluorapatite by dissolving calcium fluoride in fused disodium phosphate and lixiviating the cooled melt. Chlorapatite was formed when dicalcium phosphate was added in excess to molten calcium chloride. When precipitated calcium phos- phate was used, chlorspodiosite was obtained, Ca 3 (P0 4 ) 2 .CaCl 2 . B. Nacken, 4 by fusing calcium fluoride or chloride with calcium phos- phate, obtained both species of apatite, and also mixed crystals. Apatite has been reported as present in lead-furnace slags by W. M. Hutchins 5 and J. H.L. Vogt. 6 The composition of these slag prod- ucts, however, seems not to have been verified by analysis. Apatite is found in all classes of rocks — igneous, metamorphic, and sedimentary. In the eruptives it appears as one of the oldest secre- tions from the magma. It is more common in femic rocks than in the more siliceous varieties. Titaniferous magnetites, like those of Norway and the Adirondacks, often contain apatite in large amounts. Apatite also appears as an important vein mineral; and in these occur- rences Vogt 7 regards it as having been formed by pneumatolytic agencies. According to E. Muller, 8 apatite is strongly attacked by waters containing carbonic acid. Both lime and phosphoric acid pass into solution. A carbonated mineral allied to apatite has been described by W. Tschirwinsky, 9 under the name podolite. Its composition is represented by the formula 3Ca 3 P 2 0 8 .CaC0 3 , which is that of apatite with calcium fluoride replaced by calcium carbonate. Monazite. — Mono clinic. Composition, normally, cerium phosphate, CeP0 4 , but other rare-earth metals are always present, replacing cerium. Molecular weight, 235.25. Specific gravity, 5. Molecular volume, 47. Color, yellow, reddish, and brown. Hardness, 5 to 5.5. Xenotime. — Tetragonal. Composition, yttrium phosphate, YtP0 4 . Molecular weight, 189. Specific gravity, 4.5. Molecular volume, 42. Color, grayish white, yellowish, reddish, and commonly brown. Hardness, 4 to 5. Both monazite and xenotime have been prepared artificially by F. Badominsky, 10 who fused the amorphous phosphates of cerium or 1 Compt. Rend., vol. 52, 1861, p. 44. 2 Zeitschr. Kryst. Min., vol. 17, 1890, p. 489. 8 Jour. Phys. Chem., vol. 15, 1911, p. 464. * Centralbl. Min., Geol. u. Pal., 1912, p. 545. 6 Nature, vol. 36, 1887, p. 460. c Mineralbildung in Schmelzmassen, p. 263. 2 See his paper in Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 134, and also papers in Zeitschr. prakt. Geologie, 1894, p. 458; 1895, pp. 367, 444, 465. c Jahrb. K.-k. geol. Reichsanstalt, vol. 27, Min. pet. Mitt., 1877, p. 25. a Centralbl. Min., Geol. u. Pal., 1907, p. 279. According to W. T. Schaller (Am. Jour. Sci.,4thser., vol. 30, 1910, p. 309), podolite is identical with dahllite, which was described much earlier. M Compt. Rend., vol. 80, 1875, p. 304. 356 THE DATA OF GEOCHEMISTRY. yttrium with the corresponding chlorides. This process, however, sheds no light upon their genesis in nature. According to O. A. Derby, 1 these two species, although they occur sparingly, are very common accessory minerals in Brazilian granites and gneisses. The monazite is principally found associated with zircon, in residues from granite, syenite, and gneiss, but not in dia- base, diorite, or minette. Xenotime is a fairly constant accessory in muscovite granite. It was also found in a biotite gneiss, but was absent from phonolites and the nepheline or augite syenites. O. A. Derby 2 also reported a titaniferous magnetite from Brazil, which contained monazite, and still another association of monazite with graphite. On examining a number of granites and gneisses from New England, Derby 3 found several occurrences of monazite, and one of xenotime. W. Ramsay and A. Illiacus 4 also report the pres- ence of monazite in the pegmatites of Finland. W. E. Hidden 5 found crystals of xenotime, intergrown with zircon, in a decomposing granite in Henderson County, North Carolina. Although it is an inconspicuous mineral in rocks, monazite some- times accumulates in large quantities in residual sands, which, as a source of the rare earths, have important commercial value. The Brazilian monazite sands are described by E. Hussak and J. Reitin- ger, 6 who give very complete analyses of several samples. In North Carolina 7 the sands are derived from gneiss, and W. Lindgren 8 reports sands of granitic origin from the Idaho Basin, Idaho. THE SILICA MINERALS. Quartz. — Rhombohedral. Composition, silicon dioxide, Si0 2 . Mo- lecular weight, 60.4. Specific gravity, 2.65. Molecular volume, 22.8. Colorless when pure, but often tinted yellow, violet, red, blue, green, brown, or black. Hardness, 7. Tridymite. — Hexagonal. Composition like quartz, Si0 2 . Specific gravity, 2.3. Molecular volume, 26.3. Colorless or white. Hard- ness, 7. 1 Am. Jour. Sci., 3d ser., vol. 37, 1889, p. 109; vol. 41, 1891, p. 308. 2 Idem, 4th ser., vol. 13, 1902, p. 211. 3 Proc. Rochester Acad. Sci., vol. 1, 1891, p. 198. 4 Zeitschr. Kryst. Min., vol. 31, 1899, p. 317. & Am. Jour. Sci., 3d ser., vol. 36, 1888, p. 380. 6 Zeitschr. Kryst. Min., vol. 37, 1903, p. 550. Another memoir on the Brazilian sands, by A. Lisboa, appears in Ann. Escola de Minas, No. 6, Ouro Preto, 1903. i See report on monazite by H. B. C. Nitze, Sixteenth Ann. Kept. U. S. Geol. Survey, pt. 4, 1895, p. 667. This memoir contains a valuable bibliography. Another general paper upon monazite, thorite, and zircon, by P. Truchot, may be found in the Revue g6n. sci., vol. 9, 1898, p. 145, and, translated into English, in Chem. News, vol. 77, pp. 135, 145. s Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 63. Also in Eighteenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1898, p. 677. On monazite sand in Queensland, see Bull. Imperial Inst., vol. 3, 1905, p. 233; and in the Malay Peninsula, idem, vol. 4, 1906, p. 301. ROCK-FORMING MINERALS. 357 Cristobalite. 1 — Pseudocubic. Composition like quartz, Si0 2 . Molec- ular weight, 60.4. Specific gravity, 2.348. Molecular volume, 25.7. Melting point, 1,685°. The fused silica forms a glass, which can be worked into flasks, crucibles, beakers, etc., for chemical uses. Quartz, furthermore, is distinctly volatile at high temperatures, as was shown in a previous chapter. 2 Opal . — Amorphous silica, carrying a variable amount of water (from 2 to 13 per cent). Color, white, yellow, red, brown, green, blue, or gray. Specific gravity, 1.9 to 2.3. Hardness, 5.5 to 6.5. Free silica occurs in nature in many forms, quartz and opal being peculiarly variable species. Chalcedony, jasper, agate, flint, and other similar minerals are commonly regarded as cryptocrystalline quartz and often contain admixtures of amorphous or soluble silica, 3 with other impurities. The different modifications of silica are readily prepared by simple laboratory methods. When an orthosilicate is decomposed by a strong acid, gelatinous silica is formed, which, upon drying, becomes an amorphous mass essentially identical with opal. 4 The siliceous sinters deposited by hot springs are all classed as opal. At the hot springs of Plombi&res, in France, common opal and hyalite have been formed by the action of the waters upon an ancient Roman cement. 5 The precious opal, which fills seams and cavities in igneous rocks, such as trachyte, was probably formed by the action of hot, magmatic water upon the silicates, the latter being first decomposed and the liberated silica being deposited in the hydrous form. On the artificial production of quartz and tridymite there have been many researches. P. Schafhautl 6 simply heated a solution of col- loidal silica in a Papin digester, and obtained a crystalline deposit of quartz. H. de Senarmont 7 heated gelatinous silica with water and carbonic acid, sometimes also with hydrochloric acid, at tempera- tures of from 200° to 300°, with similar results. A. Daubree 8 pro- 1 See G. vom Rath, Neues Jahrb., 1887, Band 1, p. 198; E. Mallard, Bull. Soc. min., vol. 13, 1890, p. 172; P. Gaubert, idem, vol. 27, 1904, p. 242. The fusing temperature is that given by E. Endell and R. Rieke, Zeitschr. anorg. Chemie, vol. 79, 1912, p. 258. According to N. L. Bowen (Am. Join 1 . Sci., 4th ser., vol. 38, 1914, p. 218), it is probably somewhat higher. 2 See also A. L. Day and E. S. Shepherd on quartz glass, in Science, new ser., vol. 23, 1906, p. 670. They found that quartz began to vaporize rapidly at about the temperature of melting platinum— that is, be- tween 1,700° and 1,750°. 3 For recent discussions upon the nature of chalcedony, etc., see A. Michel L6vy and E. Munier-Chalmas, Bull. Soc. min., vol. 15, 1892, p. 159; and F. Wallerant, idem, vol. 20, 1897, p. 52. The fibrous varieties, quartzine and lutecite, are especially considered. See also H. Hein, Neues Jahrb., Beil. Band, vol. 25, 1908, p. 182, on the relation of fibrous silica to quartz and opal. According to C. N. Fenner ( Jour. Washington Acad. Sci., vol. 2, p. 476, 1912), chalcedony is probably a distinct form of silica. On gelatinous silica in an ore body, see J. H. Levings, Trans. Inst. Min. Met., vol. 21, p. 478, 1911-12. 4 For details concerning syntheses of opal, see L. Bourgeois, Reproduction artificielle des mm£raux, 1884, p. 93. 6 See A. Daubr6e, Etudes synth6tiques de g^ologie expdrimentale, 1879, p. 189. 6 Cited by L. Bourgeois, Reproduction artificielle des mindraux, 1884, p. 80. 7 Annales chim. phys., 3d ser., vol. 32, 1851, p. 142. 8 Compt. Rend., vol. 39, 1854, p. 135. 358 THE DATA OF GEOCHEMISTRY. duced quartz, together with various silicates, by the action of silicon chloride at high temperatures upon lime, magnesia, glucina, or alu- mina. He also obtained quartz by heating water to a temperature below redness in a sealed glass tube ; 1 and he furthermore observed its deposition from the waters of Plombieres. 2 To K. Chrustschoff 3 we are indebted for a series of experiments, based fundamentally upon the original processes of Schafhautl and Senarmoilt. He obtained quartz by heating an aqueous solution of colloidal silica to 250° for several months. In his latest research he added hydro- fluoboric acid to his solution of silica and varied the temperature. At 180° to 228° he obtained regular crystals, resembling the form of silica known as cristobalite, at 240° to 300° quartz was formed, and at 310° to 360° tridymite. C. Friedel and E. Sarasin 4 pro- duced quartz by heating, in a steel tube, caustic potash, gelatinous silica, and amorphous alumina nearly to redness during 14 to 38 hours. When the experiment was conducted at a higher tempera- ture they obtained tridymite and quartz side by side. W. Bruhns, 5 upon heating powdered glass to about 300° under pressure, with a weak solution of ammonium fluoride, obtained quartz; when microcline was similarly heated with hydrofluoric acid for 53 hours tridymite was formed. E. Baur 6 obtained quartz and tridymite simultaneously, as did Friedel and Sarasin, by heating a mixture of silica, sodium alumina te, and water for six hours to 520° in a steel bomb. Both species and also a soda feldspar were produced by J. Konigsberger and W. J. Muller 7 when glass was heated to 300° and upward with water alone. From the filtered and slowly cooled solution quartz and opal were deposited; the tridymite and feldspar were found in the decomposed and undissolved residue. Exceptionally fine, doubly terminated, and clear crystals of quartz were obtained by E. T. Allen 8 when a mixture of magnesium ammo- nium chloride, sodium metasilicate, and water was heated at 400° to 450° during three days in a steel bomb. All the foregoing experiments re 1 ate to the production of quartz and tridymite in the wet way, but dry methods have also been suc- cessfully employed. B,. S. Marsden 9 reports the deposition of crystal- 1 Etudes synthdtiques de geologic expSrimentale, 1879, p. 158. 2 Idem, p. 175. 3 Am. Chemist, vol. 3, 1873, p. 281. Compt. Rend., vol. 104, 1887, p. 602. Neues Jahrb., 1897, Band 1, p. 240, Refer ate. 4 Bull. Soc. min., vol. 2, 1879, pp. 113, 158. 6 Neues Jahrb., 1889, Band 2, p. 62. 6 Zeitschr. physikal. Chemie, vol. 42, 1903, p. 572. Questioned by A. L. Day and E. S. Shepherd, Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 276. 2 Centralbl. Min., Geol. u. Pal., 1906, pp. 339, 353. The authors discuss at length the relations between quartz and tridymite. 8 Cited by Day and Shepherd, op. cit., p. 297. 9 Proc. Roy. Soc. Edinburgh, vol. 11, 1880, p. 37. ROCK-FORMING MINERALS. 359 lized silica from solution in molten silver, but the first definite work upon this branch of the subject is due to G. Rose. 1 He fused adularia with microcosmic salt, and amorphous silica with a deficiency of sodium carbonate, with borax, and with wollastonite, and in each case obtained tridymite. He also observed the transformation of quartz into tridymite by simple ignition, whereas upon fusion it yielded only a glass. K. Chrustschoff 2 by fusing a rock rich in quartz also obtained tridymite; and K. B. Schmutz, 3 who melted together a granite, sodium chloride, and sodium tungstate, found plagioclase, augite, and tridymite in the subsequently cooled mass. H. Schulze and A. Stelzner 4 found tridymite as an accidental product in the muffle of a zinc furnace; and C. Velain 5 observed it with anorthite and wollastonite in the glass formed by the ashes of wheat and oats during the combustion of a grain mill. It has also been reported by A. Schwantke 6 as produced by the action of lightning upon a roofing slate. S. Meunier 7 fused silica, caustic potash, and aluminum fluoride together and obtained tridymite. P» Hautefeuille 8 heated amorphous silica with sodium or lithium tungstate to 750°, when quartz was formed; but at temperatures from 900° to 1,000° tridy- mite alone appeared. F. Parmentier, 9 repeating this experiment with sodium molybdate, produced both quartz and tridymite, and so, too, did P. Hautefeuille and J. Margottet 10 with lithium chloride as the flux. A. Brun 11 has transformed quartz glass into crystallized quartz by heating it in the vapors of alkaline chlorides to a temperature between 700° and 750°. Above 800° and below 1,000° tridymite is formed These experiments show that quartz may be produced without the intervention of water, but it is not always so formed. Quartz crystals often contain water bubbles, especially in pegmatites. Rhyolitic quartz may perhaps conform to Brun’s observations. In recent years several investigations have been reported which had for their purpose the determination of the transition point between quartz and tridymite. C. Johns 12 found that quartz sand was transformed to tridymite at 1,500°, and suggested that the true inversion temperature might be 200° lower. P. D. Quensel 13 prepared 1 Ber. Deutsch. chem. Gesell., vol. 2, 1869, p. 388. 2 Neues Jahrb., 1887, Band 1, p. 205. 3 Idem, 1897, Band 2, p. 147. * Idem, 1881, Band 1, p. 145. 6 Bull. Soc. min., vol. 1, 1878, p. 113. 6 Centralbl. Min., Geol. u. Pal., 1904, p. 87. On tridymite and cristobalite in fire-brick, see P. G. Holm- quist, Geol. For. Forhandl., vol. 33, p. 245, 1911. 7 Compt. Rend., vol. Ill, 1890, p. 509. s Bull. Soc. min., vol. 1, 1878, p. 1. 9 Cited by L. Bourgeois, Reproduction artificielle des mindraux, 1884, p. 81. m Bull. Soc. min., vol. 4, 1881, p. 244. 11 Arch. sci. phys. nat., 4th ser., vol. 25, 1908, p. 610. See also Vogt, Min. pet. Mitt., vol. 25, 1906, p. 408. 12 Geol. Mag., 1906, p. 118. 13 Centralbl. Min., Geol. u. Pal., 1906, pp. 657, 728. Quensel puts the melting point of tridymite as low as 1,560° and claims to have observed incipient fusion at 1,500°. 360 THE DATA OF GEOCHEMISTRY. both minerals; first by heating a mixture of oligoclase and quartz with tungstio oxide and later from amorphous silica and the same flux. According to his data, quartz formed below 1 ; 000° and tridymite above. The figures obtained by A. L. Day and E. S. Shepherd 1 are, however, much more precise. They found that quartz is the unstable form of silica at all temperatures above 800°, and will go over into tridymite whenever the conditions are favorable. On the other hand, when tridymite is fused with a mixture of potassium chloride and lithium chloride, quartz begins to appear at about 750°. When quartz glass was devitrified at 1,200°, or crystalline quartz was heated to the same temperature, homogeneous cristobalite was formed. According to E. S. Shepherd, G. A. Rankin, and F. E. Wright, 2 cristo- balite can be generated in pure melts of silica. More recently also in the same geophysical laboratory, C. N. Fenner 3 has studied the stability relations of the silica minerals in much greater detail and reached the following conclusions: At 870° ± 10°, quartz is trans- formed to tridymite. At 1,470° ± 10°, tridymite passes over into cristobalite. The melting point of cristobalite is put by Fenner at 1,625°, much lower than the figure already cited from Endell and Rieke; that of quartz is at least 155° lower still. It is possible to go even further in the use of 1 ‘ quartz as a geologic thermometer / ’ to use the significant expression of F. E. Wright and E. S. Larsen. 4 Quartz exists in two modifications, which differ in their optical properties, and which also yield different etch figures on treatment with cold hydrofluoric acid. One of these, a quartz, exists only below 575°; above that temperature it passes into ft quartz, the change being reversible. At ordinary temperatures all quartz is a quartz; but if at auy time it has been heated above 575°. the fact is recorded in its structure as shown by its etch figures. Quartz, therefore, in any rock, must have been formed below 800°, and its peculiarities indicate whether it was crystallized below or above 575°. Vein quartz, and the quartz of some pegmatites, were formed at the lower range of temperature; granitic and porphyry quartzes in the higher portion of the scale. Like quartz, tridymite and cristobalite exist each in two modifications, a and /?; which, with their transition temperatures have been studied by Fenner and others. Silica, then, is known in at least six forms, and possibly even more. 1 Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 276. Cf. also G. Stein, Zeitschr. anorg. Chemie, vol. 55, 1907, p. 159. 2 Am. Jour. Sci., 4th ser., vol. 28, 1909, p. 293. 3 Idem, vol. 36, 1913, p. 331. See also valuable memoirs by K. Endell and R. Rieke, Zeitschr. anorg. Chem., vol. 79, 1912, p. 239; Min. pet. Mitt., vol. 31, 1912, p. 501; A. Smits and K. Endell, Zeitschr. anorg. Chem., vol. 80, 1913, p. 176. The literature is very voluminous and can only be superficially treated here. The several authors named give many bibliographic references. 4 Am. Jour. Sci., 4th ser., vol. 28, 1909, p. 421. The two modifications of quartz were first recognized by H. Le Chatelier, Compt. Rend., vol. 108, 1889, p. 1046. See also O. Miigge, Neues Jahrb., Festband, 1907, p. 181, and other authorities cited by Wright and Larsen. ROCK-FORMING MINERALS. 361 In all probability quartz, tridymite, and cristobalite are polymers of the fundamental molecule Si0 2 . Tridymite and cristobalite are the lower, less complex polymers, and therefore are more stable at high temperatures. They are, moreover, less dense than quartz, and quartz glass, with still lower density, probably approximates most nearly to the simple molecule Si0 2 . The true formula of quartz is probably not less than Si 3 0 6 , and may be much higher. 1 The syn- thetic data all bear out these conclusions and show the difficulty of preparing pyrogenic quartz from magmatic mixtures. J. Morozewicz 2 has shown that when an artificial magma, prefer- ably aluminous, is supersaturated with silica, the excess of the latter separates out on cooling, partly as tridymite and partly as a pris- matic modification which has not been further examined. A liparite magma, however, containing about 1 per cent of tungstic acid, solidifies as a mixture of quartz, sanidine, and biotite. The function of the tungstic acid seems to be to liberate silica at the lower range of temperatures through which quartz can form, while at higher tem- peratures the reverse reaction takes place and silica is reabsorbed. These conclusions, as stated by Morozewicz, are drawn from his own observations, in connection with the experiments by Hautefeuille, which have already been cited. The formation of still a third, prismatic modification of silica, was also reported by Fouque and Levy, 3 who obtained it by fusing an excess of silica with the elements of augite, enstatite, or hypersthene. Next to the feldspars, quartz is the most abundant mineral in the crust of the earth. Tridymite is rare. From a discussion of about seven hundred analyses of igneous rocks, in comparison with their mineralogical characteristics, quartz appears to form about 12 per cent of the entire lithosphere. 4 It occurs in many forms and asso- ciations — as a primary mineral, as a secondary deposition, as a cementing substance, and as the chief constituent of quartzites and sandstones. Porphyritic quartz is found in such eruptives as quartz porphyry, rhyolite, dacite, etc. Granitic quartz, which is massive, represents the youngest secretion in granite, syenite, diorite, etc., and is peculiarly rich in liquid or gaseous inclusions. It is the sur- plus of silica left over after the bases have been satisfied, and, being probably less in amount than the eutectic ratio demands, it remains in solution to near the end of the solidifying process. We have already noted and criticized Vogt's conclusions, 5 to the effect that micropegmatite is a true eutectic mixture of feldspar and quartz, containing about 25 per cent of the latter mineral; and the glass base 1 See F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914, p. 13. 2 Min. pet. Mitt., vol. 18, 1898, pp. 158-166. 3 Synthase des mineraux et des roch.es, pp. 88, 89. * F. W. Clarke, Bull. U. S. Geol. Survey No. 228, 1904, pp. 19, 20. 6 See p. 302. 362 THE DATA OF GEOCHEMISTRY. or groundmass of many rocks has similar composition. It is easy to understand from a consideration of the synthetic experiments why silica should form glass during the solidification of a magma, but the generation of quartz is a less simple matter. Lavas begin to solidify at temperatures above the transition point of quartz, and the development of the latter in such a rock as rhyolite is probably a result of very slow cooling, or even supercooling. That is, the temperature of the cooling mass is probably held for a long time just below the transition point, so that quartz forms instead of tridymite. The formation of quartz, especially in plutonic rocks, is possibly also conditioned by pressure, and it is likely that magmatic water, by reducing the temperature of fusion, may aid in its deposition. Under great pressure the denser quartz should tend to form rather than tridymite. The latter mineral is characteristic of volcanic rocks, especially of rhyohte, trachyte, and andesite. The occurrence of tridymite in Mont Pelee has been especially studied by A. Lacroix . 1 Rocks collected soon after the eruptions contained none of this min- eral, which began to appear about six months later. Lacroix there- fore regards tridymite not as an immediate crystallization from the magma, but as having been formed, after cooling, by the action of magmatic gases on the andesitic paste. In recent lavas quartz occurs but rarely. In some cases, however, quartz has been observed in basalts — that is, in rocks which are capable of assimilating, as sili- cates, more silica than they contain — but in most instances this quartz is regarded as foreign and representing accidental inclusions. There are quartz basalts, however, in which the quartz appears to be an original and early secretion from the magma, and these examples are not easy to explain. In fact, no final explanation of them has yet been proposed . 2 The dissociation hypothesis, offered in the pre- ceding chapter to account for the coexistence of quartz and mag- netite, has perhaps the maximum of probability. Secondary quartz may be produced by several processes. Certain hydrous silicates, like talc and pectohte, are broken down by mere ignition, with liberation of free silica. Possibly this fact may have some bearing upon the formation of quartz as a contact mineral. Most silicates are decomposable by percolating waters, and we have already seen that silica, in a greater or less amount, is almost invari- ably present in springs and rivers. Silica so dissolved is redeposited by evaporation as opal, but when alkalies are present, according to 1 Bull. Soc. min ., vol. 28, 1905, p. 56. See also Lacroix on tridymite from Vesuvius, idem, vol. 31, 1908, p. 323. 2 See J. P. Iddings, Bull. U. S. Geol. Survey No. 66, 1890, and Am. Jour. Sci., 3d ser., vol. 36, 1888, p. 208, on quartz basalts from New Mexico; and J. S. Diller, Bull. U. S. Geol. Survey No. 79, 1891 , on quartz basalts from California. Also a note by Diller, in Science, 1st ser., vol. 13, 1889, p. 232, on porphyritic quartz in eruptive rocks. In Bull. No. 79 Diller cites many references to similar rocks from other localities. Iddings discusses at some length the possible origin of the quartz but reaches no certain conclusions. ROCK-FORMING MINERALS. 363 G. Spezia/ quartz is formed. Spezia also observed that when opal was heated with a solution of an alkaline silicate it was transformed into an aggregate of quartz crystals. At high temperatures a dilute solution of sodium silicate dissolves quartz to some extent, but the latter is redeposited at lower temperatures. 1 2 A 5 per cent solution of borax, under pressure and at 290° to 315,° attacks quartz strongly, but at 12° to 16°, even under very great pressure, no solution was noted. 3 These experiments by Spezia shed much light upon the deposition of opal or quartz as a cementing material. There is also a suggestive experiment reported by Ramsay and Hunter, 4 who heated amorphous silica with water to 200° in a sealed tube. In two days the silica had caked together to a granular mass of glass. The quartz crystals which line cavities in chalcedony or wood opal may have been formed by the action of alkaline silicates upon the last-named min- eral. Much has been written upon the solubility of quartz, and the corrosion of quartz pebbles has repeatedly been noted. 5 6 Quartz may be dissolved and replaced by pseudomorphs of other minerals, and silicates are often decomposed by percolating waters, yielding pseu- domorphs of quartz. Geological literature contains innumerable references to replacements of this order. ✓ THE FELDSPARS. Orthoclase. — Monoclinic. Composition, KAlSi 3 0 8 . Molecular weight, 279.4. Specific gravity, 2.56. Molecular volume, 109.1. Colorless, often reddish or yellowish, sometimes gray or green. Hardness, 6 to 6.5. Microcline. — Triclinic. Composition, specific gravity, hardness, etc., like orthoclase. Albite. — Triclinic. Composition, NaAlSi 3 0 8 . Molecular weight, 263.3. Specific gravity, 2.605. Molecular volume, 101.1. Colors as in orthoclase, commonly white. Hardness, 6 to 6.5. Anorthoclase. — Triclinic. Intermediate in composition between albite and microcline. Anorthite. — Triclinic. Composition, CaAl 2 Si 2 0 8 . Molecular weight, 279.1. Specific gravity, 2.765. Molecular volume, 100.9. Fuses at 1,550°. Color, white, grayish, reddish. Hardness, 6 to 6.5. 1 Jour. Chem. Soc., vol. 76, pt. 2, 1899, p. 300. 2 Idem, vol. 78, pt. 2, 1900, p. 595. 3 Idem, vol. 80, pt. 2, 1901, p. 605. For Spezia’s original papers, of which these notes are abstracts, see Atti. Accad. Torino, vol. 31, 1896, p. 196; vol. 33, 1898, pp. 289, 876; vol. 35, 1900, p. 750; and vol. 36, 1900- 1901, p. 631. * Rept. British Assoc. Adv. Sci., 1882, p. 239. 6 See C. W. Hayes, Bull. Geol. Soc. America, vol. 8, 1896, p. 213; M. L. Fuller, Jour. Geology, vol. 10, 1902, p. 815; and C. H. Smyth, Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 277. On the chemical reactivity of quartz, due to its solubility, see F. Rinne, Centralbl. Min., Geol. u. Pal., 1904, p. 333. On the solubility of quartz in alkaline solutions, as conditioned by the fineness of its subdivision, see G. Lunge and C. Mill- berg, Zeitschr.' angew. Chemie, 1897, p. 393. R. Schwarz finds (Zeitschr. anorg. Chemie, vol. 76, 1912, p. 422), that the three silica minerals are very different as regards solubility in reagents. Tridymite and cris- tobalite dissolve more easily and rapidly than quartz, and quartz glass more easily still. 364 THE DATA OF GEOCHEMISTRY. There are several minor additions to be made to this list. A monoclinic equivalent of albite appears to occur as an admixture in many examples of orthoclase, and sometimes is in excess of the potas- sium compound. According to P. Barbier and A. Prost 1 this soda orthoclase is very nearly represented by a supposed albite from Kragero, Norway. Similarly, sodium may replace calcium in anor- thite, forming a triclinic isomer of nephelite, with the formula Na 2 Al 2 Si 2 0 8 . This compound has been prepared synthetically, and also identified by H. S. Washington and F. E. Wright 2 as a constit- uent of a feldspar from the Island of Linosa, east of Tunis. For the sodium anorthite itself, they propose the name carnegieite, and for the mixed feldspar, in which it is associated with albite and anorthite, the name anemousite. The mineral celsian may be a barium anorthite, BaAl 2 Si 2 0 8 . Hyalophane is another barium feldspar, which, however, is mono- clinic, and appears to be a mixture of a salt like celsian with ortho- clase. Traces of barium are often found in feldspars. Albite and anorthite form the extreme ends of a series of minerals known as the plagioclase feldspars. Several stages of mixture in this series have received distinctive names, as shown below. The symbols Ab and An represent albite and anorthite, respectively: Oligoclase AbA^i to AbaAn^ Andesine * AbaA^ to AbjAnj. Labradorite Ab^A^i to AbjAng. Bytownite Ab x An 3 to AbjAiie. These feldspars are generally regarded as isomorphous mixtures of the two end species; but some authorities consider them as repre- senting definite compounds, which, in their turn, may commingle isomorphously in any proportion. 3 The prevalent opinion, however, seems to be fully confirmed by the most recent investigations, espe- cially by those of A. L. Day and his colleagues, E. T. Allen, R. B. Sosman, and N. L. Bowen, 4 whose determinations of melting points form a regular linear series. The latest figures, representing com- plete fusion, by Bowen, are as follows : Melting points of feldspar. °G. An 1,550 AbxAn 5 1,521 AbiAn 2 1,490 AbxAn! 1,450 °C. Ab 2 An! 1,394 AbgAn! 1,362 Ab 4 An t 1,334 Ab 5 An t 1,265 1 Bull. Soc. chim., 4th ser., vol. 3, 1908, p. 894. W. T. Schaller (Am. Jour. Sci., 4th ser., vol. 30, 1910, p. 358) proposes to name this soda orthoclase barbierite. 2 Am. Jour. Sci., 4th ser., vol. 29, 1910, p. 52. For synthetic data see N. L. Bowen, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 551. He gives references to earlier literature. s See, for example, W. Tarrassenko, Zeitschr. Kryst. Min., vol. 36, p. 182, 1902. 4 Day and Allen, Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 93. Day and Sosman, idem, vol. 31, 1911, p. 341. Bowen, idem, vol. 35, 1913, p. 577. ROCK-FORMING MINERALS. 365 These figures give a regular curve, but as the albite end of the series is approached the mixtures become too viscous to admit of good melting-point measurements. It should be noted that the observations were made upon artificial preparations of great purity. Of all the feldspars anorthite is the one most easily made pyro- genically. In the investigation by Day and Allen just cited it was prepared without difficulty by simply fusing its constituent oxides together; and this observation is in accord with the results obtained by previous experimenters. J. H. L. Vogt 1 observed its formation in slags, and J. Morozewicz 2 repeatedly obtained feldspars varying from labradorite to nearly pure anorthite in his experiments with artificial magmas. Fouque and Levy 3 obtained anorthite directly from its constituents; and S. Meunier, 4 upon fusing silica, lime, and aluminum fluoride together, found sillimanite, tridymite, and anor- thite in the resultant mass. Anorthite is also formed by the break- ing down of other more complex silicates. A. Des Cloizeaux, 5 by fus- ing garnet and vesuvianite, obtained crystals which Fouque and Levy identified as anorthite; and similar results are reported, with much more detail, by C. Doelter and E. Hussak. 6 Doelter 7 also found anorthite among the products formed by fusing epidote, axinite, chab- azite, and scolecite. Finally, C. and G. Friedel 8 prepared anorthite in the wet way by heating muscovite with lime, calcium chloride, and a little water to 500° in a steel tube. Feldspars analogous to anor- thite, oligoclase, and labradorite, but containing strontium, barium, or lead in place of calcium, were also obtained by Fouque and Levy 9 when mixtures of silica, alumina, sodium carbonate, and the proper monoxide were heated together to temperatures a little below the point of fusion. Plagioclase feldspars containing potassium have been made synthetically by E. Dittler. 10 A microcline from the Ilmen Mountains, described by W. Vernadsky, 11 contained rubidium to the extent of 3.12 per cent Rb 2 0. All attempts to prepare the alkali feldspars by simple dry fusion have failed. Whether the constituent substances are taken or the natural minerals themselves are fused, the product is always a glass, without any distinct evidences of crystallization. Anorthite, as we have seen, crystallizes easily, and the intermediate feldspars, which form without difficulty near the anorthite end of the series, become 1 Mineralbildung in Schmelzmassen, p. 181. 2 Min. pet. Mitt., vol. 18, 1898, p. 156. 3 Syntbese des mineraux et des roches, p. 138. 4 Compt. Rend., vol. Ill, 1890, p. 509. 5 Manuel de min4ralogie, vol. 1, 1862, pp. 277, 543. 6 Neues Jahrb., 1884, Band 1, p. 158. 7 Idem, 1897, Band 1, p. 1; Allgemeine und chemische Mineralogie, p. 183. 8 Compt. Rend., vol. 110, 1890, p. 1170. 0 Synthase des mindraux et des roches, p. 145. xo Min. pet. Mitt., vol. 29, 1910, p. 273. u Bull. Soc. min., vol. 36, 1914, p. 258. 366 THE DATA OF GEOCHEMISTRY. more and more unmanageable as we approach albite. This fact was observed by Fouque and Levy 1 and corroborated by Day and Allen, the latter having also shown that the viscosity of the alkaline com- pounds impedes their crystallization, at least within any reasonable time which can be allowed for a laboratory experiment. Allnte, how- ever, may be recrystallized, as J. Lenarcic 2 has shown, when it is fused with half its weight of magnetite. The mixture forms a mobile liquid in which crystallization can take place. Other substances also render crystallization possible. P. Hautefeuille 3 heated an alkaline alumosilicate of sodium to 900°-l,000° with tungstic acid and obtained albite. A similar experiment with a potassium alumo- silicate yielded orthoclase, 4 and a mixture of silica, alumina, and acid potassium tungstate gave the same result. By heating a potas- sium alumosilicate mixture with alkaline phosphates to which an alkaline fluoride had been added, Hautefeuille 5 produced both quartz and orthoclase, and a potassium feldspar was also obtained by Doel- ter 6 when a mixture corresponding to KAlSi0 4 was fused with potas- sium fluoride and silicofluoride. How these extraneous substances act is not clear. Day and Allen, 7 repeating a part of Hautefeuille’s work, heated a powdered albite glass with sodium tungstate and succeeded in bringing about crystallization. The fragments of glass, however, became crystalline without change of form, and their out- lines were unaltered — that is, the transformation from the vitreous to the crystalline modification took place without solution of the material. The mechanism of this reaction is quite unexplained. By hydrochemical means the alkali feldspars are more easily pre- pared. C. Friedel and E. Sarasin 8 heated gelatinous silica, precipi- tated alumina, and caustic potash together, with a little water, to dull redness in a steel tube. Quartz and orthoclase were produced. In a later investigation 9 they heated a mixture having the composi- tion of albite, with an excess of sodium silicate, to about 500° and obtained albite. The same process, essentially, was followed by K. Chrustschoff , 10 who heated an aqueous solution of dialyzed silica with a little alumina and caustic potash to 300° during several months, when quartz and orthoclase formed. C. and G. Friedel 11 also pre- pared orthoclase by heating muscovite with potassium silicate and water to 500°. In a series of experiments in which amorphous silica 1 Synthese des min4raux et des roches, pp. 142-145. 2 Centralbl. Min., Geol. u. Pal., 1903, p. 705. 3 Compt. Rend., vol. 84, 1877, p. 1301. 4 Idem, vol. 85, 1877, p. 952. 3 Idem, vol. 90, 1880, p. 830. 6 Neues Jatirb., 1897, Band 1, p. 1. 7 Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 117. 3 Compt. Rend., vol. 92, 1881, p. 1374. 8 Idem, vol. 97, 1883, p. 290. io Idem, vol. 104, 1887, p. 602. u Idem, vol. 110, 1890, p. 1170, ROCK-FORMING MINERALS. 367 was heated with potassium or sodium aluminate and water to 520° in a steel bomb, E. Baur 1 determined the conditions under which quartz alone, feldspar alone, or both together, could form. When the silica was in excess, quartz appeared ; with silica and the alumi- nate in nearly equal proportions, both minerals crystallized; when the aluminate preponderated in the mixture, only feldspar formed. The feldspars are by far the most abundant of all the minerals and form nearly 60 per cent of the material contained in the igneous rocks. 2 Among the latter only the pyroxenites, peridotites, leucitites, and nephelinites contain no feldspars, or at most contain them in quite subordinate quantities. The monoclinic alkali feldspars are especially characteristic of the more siliceous plutonic rocks, although they also occur in many 'erup fives and in metamorphic schists. In granite, for example, orthoclase, quartz, and muscovite are the con- spicuous minerals. Albite is also found under similar conditions. In the less siliceous rocks, such as gabbro or basalt, the plagioclases are more abundant, and the feldspars approach anorthite in compo- sition as the proportion of silica in a magma decreases. This state- ment, however, must he construed as indicating a tendency, not as the formulation of a distinct rule. The more siliceous rocks contain preferably the more siliceous feldspars, and vice versa. Anorthite has also been repeatedly observed in meteorites, and it is not uncom- mon as a contact mineral in limestones. 3 Orthoclase, probably of aqueous origin, sometimes occurs as a gangue mineral in metalliferous fissure veins. 4 The feldspars are all highly alterable minerals and their alteration products are both numerous and important. They are attacked by water alone, more so by water containing carbon dioxide, and still more vigorously by acid waters, such as issue from volcanic vents or are formed by the oxidation of sulphides. Alkaline solutions also exert a powerful decomposing action upon this group of silicates. Among the many experiments relative to this class of reactions those of A. Daubree 5 6 are perhaps the most classic. Fragments of ortho- clase were agitated with water alone by revolution in a cylinder of iron during 192 hours. From 5 kilograms of the feldspar 12.6 grams of K 2 0 were thus extracted and found in the filtered solution. To water charged with carbon dioxide 2 kilograms of orthoclase, after 10 days of agitation, yielded 0.27 gram of K 2 0, with 0.75 gram of 1 Zeitschr. physikal. Chemie, vol. 42, 1903, p. 567. The paper is illustrated by diagrams based upon the phase rule. 2 See F. W. Clarke, Bull. U. S. Geol. Survey No. 419, 1910, p. 9. 3 For example, crystals of anorthite occur with epidote in the limestone of Phippsburg, Me., and also with garnet, scapolite, etc., at Raymond, Me. See Bull. U. S. Geol. Survey No. 113, 1893, p. 110, and Bull. No. 167, 1900, p. 69. C. H. Warren (Am. Jour. Sci., 4th ser., vol. 11, 1901, p. 369) describes crystals of anorthite from the limestone of Franklin, N. J., near its contact with granite. 4 W . Lindgren (Am. Jour. Sci., 4th ser., vol. 5, 1898, p. 418) has described an occurrence of this kind near Silver City, Idaho. He gives a number of references to other localities. 6 Etudes synthetiques de geologie experimentale, 1879, pp. 268-275. 368 the data of geochemistry. v free silica. With alkaline solutions, especially at elevated tempera- tures and under pressure, the changes are even more striking, as shown by J. Lemberg’s investigations . 1 Labradorite, heated 324 hours to 215° with a sodium carbonate solution, yielded cancrinite. Other feldspars, similarly treated, but with variations in detail, were trans- formed into analcite. With glasses formed by the fusion of feldspars, and with potassium carbonate, zeolites of the chabazite and phillip- site series were produced. The end products of the alteration of feldspars are commonly kaolinite and quartz. Other hydrous silicates of alumina are prob- ably also formed. When the alkalies have not been wholly withdrawn muscovite is a common alteration product. Many of the zeolites are generally interpreted as hydrated feldspars, those which contain lime having been derived from plagioclase. From anorthite calcite may be formed. Scapolites , 2 epidote, and zoisite are also not uncommon derivatives of feldspars. Finally, by substitution of bases, one feld- spar may pass into another, as in the alteration of orthoclase into albite . 3 LEUCITE AND ANALCITE. Leucite. — Isometric. Composition, KAlSi 2 0 6 . Molecular weight, 219. Specific gravity, 2.5. Molecular volume, 87.6. Color, white to gray. Hardness, 5.5 to 6. Fuses at about 1,420°. Analcite. — Isometric. Composition* NaAlSi 2 0 6 .H 2 0. Molecular weight, 220.9. Specific gravity, 2.25. Molecular volume, 98.2. Colorless or white, sometimes tinted by impurities. 4 Hardness, 5 to 5.5. Although leucite and analcite are widely separated in miner alogical classification, one being placed near the feldspars and the other among the zeolites, they belong chemically together. They are simi- lar in form and in composition, and are connected by so many rela- tions that they can not be adequately studied apart. Analcite, to be sure, differs from leucite in respect to hydration, but G. Friedel 5 has shown that its water is not a part of the essential crystalline molecule. When heated in sealed tubes with dissociating ammonium chloride, leucite and analcite both yield the same ammonium derivative, 6 NH 4 AlSi 2 0 6 . Furthermore, as the experiments of J. Lemberg 7 and S. J. Thugutt 8 have shown, the two species are easily convertible, the one into the other. When leucite is heated to 180-195° with a solu- 1 Zeitschr. Deutsch. geol. Gesell., vol. 39, 1887, p. 559. 2 See J. W. Judd, Mineralog. Mag., vol. 8, 1889, p. 186, on the alteration of plagioclase into scapolite. 3 For an example of this kind see F. A. Genth, Proc. Am. Philos. Soc., vol. 20, 1882, p. 392. 4 On variations in the composition of analcite, see H. W. Foote and W. M. Bradley, Am. Jour. Sci.. 4th ser., vol. 33, 1912, p. 433. 6 Bull. Soc. min., vol. 19, 1896, p. 363. 6 F. W. Clarke and G. Steiger, Bull. U. S. Geol. Survey No. 207, 1902. 7 Zeitschr. Deutsch. geol. Gesell., vol. 28, 1876, pp. 537 et seq. 8 Mineralchemische Studien, Dorpat, 1901, pp. 100, 101, ROCK-FORMING MINERALS. 369 tion of sodium chloride or sodium carbonate, analcite is formed. Analcite, similarly treated with potassium salts, is converted into leucite. Leucite and analcite are both easily prepared synthetically. Leu- cite can be formed by simply fusing together its constituent oxides and cooling the mass slowly. This process was followed by Fouque and Levy, 1 who also formed leucite, with other minerals, from various artificial magmas. 2 By fusion of its constituents with potassium van- adate, P. Hautefeuille 3 obtained measurable crystals of leucite. The same result followed the fusion of muscovite with potassium vanadate. Syntheses of leucite by indirect methods, with the intervention of fluorides or of silicon chloride, have also been effected by S. Meu- nier 4 and A. Duboin. 5 C. Doelter, 6 by fusing a mixture equivalent to AU0 3 + 2Si0 2 with sodium fluoride, prepared a soda leucite, NaAlSi 2 0 6 - When microcline and biotite are fused together, leucite appears among the products; 7 and Doelter 8 found that it was formed when muscovite, lepidolite, or zinnwaldite was fused alone. It was also produced hydro chemically by C. and G. Friedel 9 when muscovite was heated to 500° in a steel tube with silica and a solution of potassium hydroxide. The syntheses of analcite have all been effected under pressure, and in the wet way. A. de Schulten 10 heated sodium silicate, caustic soda, and water, in contact with aluminous glass, at a temperature of 180° to 190°. He also produced analcite by heating a solution of sodium silicate with sodium aluminate, in proper proportions, to 180° for eighteen hours. 11 C. Friedel and E. Sarasin 12 prepared analcite by heating precipitated aluminum silicate with sodium silicate and water to 500° in a sealed tube. J. Lemberg 13 derived analcite from andesine and oligoclase by prolonged heating with sodium carbonate solutions at 210° to 220°. These transformations illustrate the ready formation of analcite as a secondary mineral. They are not, however, all strictly similar. Analcite derived from leucite can be transformed into leucite again, as we have already seen; but according to S. J. Thugutt 14 the 1 Synthese des min&aux et des roches, p. 153. 2 Bull. Soc. min., vol. 2, 1879, p. Ill; vol. 3, 1880, p. 118. 8 Cited by L. Bourgeois, Reproduction artificielle des minOraux, p. 130. 4 Compt. Rend., vol. 90, 1880, p. 1009; vol. Ill, 1890, p. 509. 6 Idem, vol. 114, 1892, p. 1361. 6 Neues Jahrb., 1897, Band 1, p. 1. 7 Fouqu6 and L6vy, Synthase des min&aux et des roches, p. 77. » Loc. cit. 9 Compt. Rend., vol. 110, 1890, p. 1170. i° Idem, vol. 90, 1880, p. 1493; Bull. Soc. min., vol. 3, 1880, p. 150. m Idem, vol. 94, 1882, p. 96. 12 Idem, vol. 97, 1883, p. 290. I 8 Zeitschr. Deutsch. geol. Gesell., vol. 39, 1887, p. 559. 14 Neues Jahrb., Beil. Band 9, 1894-95, p. 604. 97270°— Bull. 616—16 24 370 THE DATA OF GEOCHEMISTRY. reaction with andesine is not reversible. The two alterations, there- fore, are chemically unlike. Analcite may also be generated by alter- ation from elseolite and segirite . 1 When formed with other zeolites, it is the earliest one to appear. Leucite is a mineral characteristic of many recent lavas, but not found in the abyssal rocks. Its absence from the latter and older depositions may be due to its easy alteration into other species; but such an explanation is of course only tentative. Its formation takes place only when the potassium of a magma is in excess over the amount required to form feldspars. When the excess is small, leucite and feldspar may both appear; when it is large enough, leucite alone forms. Comparatively speaking, it is rather a rare mineral; a fact which is possibly explained by some observations of A. Lagorio . 2 In an artificial leucite-tephrite magma, kept at a red heat, the difficultly fusible leucite crystallizes out. If, then, the temperature is raised, the mineral redissolves ; if lowered, the mass becomes so viscous that the crystallization of leucite ceases. In brief, the formation of leucite seems to be possible only through a very narrow range of tempera- tures, and the favorable conditions do not often occur . 3 Analcite is most frequently found as a secondary mineral, the prod- uct of zeolitization; and until recent years it was supposed to have no other origin. It was often noted in eruptive rocks, but it was supposed to be always a product of alteration. It is now generally recognized, however, that analcite may occur as an original pyrogenic mineral; but, being a hydrated species, it can so' appeal* only in deep-seated rocks, where it has been formed under pressure. W. Lind- gren , 4 for example, identified it in the sodalite syenite of Square Butte, Montana. In certain rocks analcite has probably been erro- neously identified as glass; for instance, in the monchiquites, which L. V. Pirsson 5 interprets as analcite basalts equivalent to the similar leucite lavas. W. Cross , 6 has described an analcite basalt from near Pikes Peak, Colorado, and has also identified primary analcite in the phonolites of Cripple Creek . 7 The groundmass of a tinguaite from Manchester, Massachusetts, according to H. S. Washington , 8 consists of analcite and nepheline; and J. W. Evans 9 has identified the min- eral in a monchiquite from Mount Girnar, India. In the last instance some of the analcite has been transformed into a mixture of feldspar and nepheline. The extreme case cf an analcite rock, however, is 1 See W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1890, pp. 223, 333. 2 Zeitschr. Kryst. Min., vol. 24, 1895, p. 293. s On the formation oi leucite in igneous rocks, see H. S. Washington, Jour. Geology, vol. 15, 1907, pp. 257, 357. * Am. Jour. Sci., 3d ser., vol. 45, 1893, p. 286. 8 Jour. Geology, vol. 4, 1896, p. 679. 6 Idem, vol. 5, 1897, p. 684. 7 Sixteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1895, p. 36. 8 Am. Jour. Sci., 4th ser., vol. 6, 1898, p. 182. 9 Quart. Jour. Geol. Soc., vol. 57, 1901, p. 38. ROCK-FORMING MINERALS. 371 the heronite from Heron Bay, Lake Superior, described by A. P. Coleman. 1 This is a dike rock containing analcite, plagioclase, ortho- clase, and segirine, in which the analcite forms 47 per cent of the mass. In the analcite diabase described by H. W. Fairbanks, 2 the analcite may have been derived from nepheline. It is partly replaced by feldspar, and partly altered into a mineral which may be prehnite. Analcite also alters into kaolin. 3 Alterations of leucite into analcite have been repeatedly observed, as in the Saxon Wiesenthal 4 and in the Highwood Mountains, Mon- tana. 5 The most notable transformation of leucite, however, is into pseudomorphs of mixed orthoclase and nepheline. 6 The “pseudo- leucite” crystals of Magnet Cove, Arkansas, are a mixture of this kind. THE NEPHELITE GROUP. Nephelite or elseolite. — Hexagonal. Simplest empirical formula, NaAlSi0 4 . Corresponding molecular weight, 142.5. Specific grav- ity, 2.55 to 2.65. Molecular volume, 54.8. Melting point, 1,526°, Bowen. Normally white or colorless; often tinted yellow, gray, greenish, or reddish by impurities. Hardness, 5.5 to 6. Kaliophilite or phacelite. — Hexagonal. Composition, KAlSi0 4 . Molecular weight, 158.6. Specific gravity, 2.5 to 2.6. Molecular volume, 6.1. Colorless. Hardness, 6. Eucryptite. — Hexagonal. Composition, LiAlSi0 4 . Molecular weight, 126.5. Specific gravity, 2.67. Molecular volume, 47.3. Colorless or white. Only known as produced by the alteration of spodumene. Kaliophilite and eucryptite are rare minerals, having slight geo- logical significance. They are included here because of the light they shed upon the composition of nephelite. The formula given for the latter species is analogous to the formulae of kaliophilite and eucryptite, and is also that of the artificial mineral. Natural neph- elite or elseolite always varies from the theoretical composition, and approximates more nearly the formula Na 6 K 2 Al 8 Si 9 0 34 . This varia- tion is probably due, first, to isomorphous admixtures of kaliophilite, 1 Jour. Geology, vol. 7, 1899, p. 431. 2 Bull. Dept. Geology Univ. California, vol. 1, 1895, p. 273. See also B. R. Young, Trans. Edinburgh Geol. Soc., vol. 8, 1903, p. 326, on analcite diabase in Scotland; C. W. Knight, Canadian Rec. Sci., vol. 9, 1905, p. 265, on an analcite- trachyte tuff from southwestern Alberta; and A. Pelikan, Min. pet. Mitt., vol. 25, 1906, p. 113, on two analcite phonolites from Bohemia. Essexites and teschenites from Western Scot- land, rich in primary analcite, are described by G. W. Tyrrell, Trans. Geol. Soc. Glasgow, vol. 13, 1909, p. 299, and Geol. Mag., 1912, pp. 66, 120. On analcite basalts from Sardinia, see H. S. Washington, Boll. Soc. geol. ital., vol. 33, 1914, p. 147. A still later paper on primary analcite, by J. D. MacKenzie, is published in Am. Jour. Sci., 4th ser., vol. 39, 1915, p. 571. 3 W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1890, p. 199. 4 See A. Sauer, Zeitschr. Deutsch. geol. Gesell., vol. 37, 1885, p. 452. 5 W. H. Weed and L. V. Pirsson, Am. Jour. Sci., 4th ser., vol. 2, 1896, p. 315. 8 See Sauer, loc. cit.; J. F. Williams, Ann. Rept. Geol. Survey Arkansas, 1890, vol. 2, p. 267; E. Hussak, Neues Jahrb., 1890, pt. 1, p. 166; and E. Scacchi, Rendiconti Accad. Napoli, vol. 24, p. 315, 872 THE DATA OF GEOCHEMISTRY. and possibly also to the presence of silica or albite as impurities in the normal orthosilicate. This supposition is put in more definite shape by H. W. Foote and W. M. Bradley/ who regard natural nephelite as the normal compound with other silicates or silica present in “solid solution.” The same hypothesis may explain the similar variations in cancrinite, sodalite, and other species. The expression “solid solution,” however, should be used with caution. It probably confuses a number of different phenomena, to which specific names quite properly belong. Isomorphous mixtures or mix-crystals are well known; occlusion describes another form of im- purity; a solid (or solidified) solution like glass is not at all the same as either of the others. Under the name pseudonephelite F. Zam- bonini 1 2 has described a normal isomorphous mixture from Capo di Bove having the formula (Na,K)AlSi0 4 . The equivalency of nephelite and kaliophilite is well shown by an experiment of J. Lem- berg. 3 He heated elssolite one hundred hours to 200° with a solution of potassium silicate, and obtained an amorphous product having the composition KAlSi0 4 . P. Hautefeuille 4 prepared an artificial nephelite by fusing a mix- ture of silica and sodium aluminate with a flux of lithium vanadate. Fouque and Levy 5 obtained the mineral more directly by fusing its constituents together, and so, too, did C. Doelter. 6 Doelter’s prepara- tion agreed closely with the empirical formula NaAlSi0 4 . Accord- ing to Fouque and Levy, nephelite is one of the minerals which crystal- lize most easily from fusion. S. Meunier 7 prepared nephelite less simply, by fusing silica, alumina, and soda with cryolite; and A. Duboin 8 effected the synthesis of kaliophilite when potassium fluor- ide, alumina, and silica or potassium fluosilicate were fused together. By similar processes Doelter 9 obtained both nephelite and kaliophi- lite. C. and G. Friedel 10 converted muscovite into nephelite by heat- ing with a solution of caustic soda to 500° in a steel tube. The pres- ence of nephelite in pseudomorphs after leucite was noted in the description of the latter mineral. An amorphous silicate having the 1 Am. Jour. Sci., 4th ser., vol. 31, 1911, p. 25; vol. 33, 1912, p. 439. Other recent discussions of the con- stitution of nephelite are by J. Morozewicz, Bull. Acad. Sci. Cracow, 1907, p. 958; Silvia Hillebrand Sitzungsb. Akad. Wien, vol. 119, pt. 1, 1910; S. J. Thugutt, Compt. Rend. Soc. Sci. Warsaw, 1913, p. 856; W. T. Schaller, Zeitschr. Kryst. Min., vol. 50, 1912, p. 343; and N. L. Bowen, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 551. 2 Jour. Chem. Soc., vol. 98, pt. 2, 1910, p. 1078. Abst. from Rend. acad. sci. fis. mat., Napoli, 1910. a Zeitschr. Deutsch. geol. Gesell., vol. 37, 1885, p. 966. * Cited by Fouqu£ and L£vy, Synthase des min6raux et des roches, p. 155. 6 Loc. cit. 6 Zeitschr. Kryst. Min., vol. 9, 1884, p. 321. i Compt. Rend., vol. Ill, 1890, p. 509. s Idem, vol. 115, 1892, p. 56. 9 Neues Jahrb., 1897, Band 1, p. 1. 10 Compt. Rend., vol. 110, 1890, p. 1170. By the same process, using caustic potash instead of soda, G. Friedel effected the synthesis of kaliophilite: Bull. Soc. min., vol. 35, p. 470, 1912. Recent syntheses of nephelite, kaliophilite, and eucryptite by direct fusion are described by A. S. Ginsberg, Zeitschr. anorg, Chemie, voL 73, 1912, p 277. BOCK-FORMING MINERALS. 378 composition of nephelite was obtained by R. Hoffmann 1 when kaolin and dry sodium carbonate were heated together, and a similar result was reached by A. Gorgeu 2 and P. G. Silber. 3 When Gorgeu heated kaolin with potassium iodide, a salt like kaliophilite was formed. In these reactions the temperature was kept below that at which the materials would sinter together. Nephelite is rarely found except in igneous rocks. 4 The glassy crystallized variety found in recent lavas is commonly known by the first name of the species; the massive, opaque, or coarsely crystalline mineral of the older rocks is called elaeolite. Phonolite, nephelinite, nepheline basalt, and elaeolite syenite are among the important rocks in which nephelite is an essential species. Its presence indicates an excess of soda in a magma over the amount required to form feld- spars, and it is one of the latest minerals to be deposited. 5 6 In a nepheline syenite from an island off the coast of Guinea, A. Lacroix 0 found crystals of sodium fluoride, NaF. This new mineral species he named villiaumite. Nephelite and elaeolite are peculiarly subject to alteration. 7 Na- trolite, analcite, hydronephelite, thomsonite, sodalite, muscovite, and kaolin are among the products thus formed. Eucryptite also alters into muscovite. 8 This indicates that the simplest empirical for- mulae of the nephelite minerals should be tripled, for the formula of muscovite is Al 3 (Si0 4 ) 3 KH 2 . THE CAN CRINITE- S OD AEITE GROUP. Cancrinite. — Hexagonal. Composition uncertain, but probably best represented by the formula Al 3 Na 4 HCSi 3 0 15 . Corresponding molecular weight, 511.5. Specific gravity, 2.4. Molecular volume, 213. Color commonly yellow, but also white, gray, greenish, bluish, or reddish. Hardness, 5 to 6. Sodalite . 9 — Isometric. Composition normally Al 3 Na 4 Si 3 0 12 Cl, but variable. Molecular weight, 486. Specific gravity, 2.2. Molecular volume, 221. Color, white, gray, greenish, yellowish, reddish, very often bright blue. Hardness, 5.5 to 6. Hauynite. — Isometric. Composition, Al 3 Na 3 CaSSi 3 0 16 , but vary- ing in the relative proportions of Na and Ca. Molecular weight, 1 Liebig’s Annalen, vol. 194, 1878, p. 5. 2 Annales chim. phys., 6th ser., vol. 10, 1887, p. 145. 3 Ber. Deutsch. chem. Gesell., vol. 14, 1881, p. 941. * Nephelite is reported by Max Bauer (Neues Jahrb., 1896, Band 1, p. 85; 1897, Band 1, p. 258) in certain crystalline schists, and also associated with chlorite in jadeite. 6 See the experiments of J. Morozewicz, Min. pet. Mitt., vol. 18, 1898, pp. 1, 105. Compare also J. LenarCifi, Centralbl. Min., Geol. u. Pal., 1903, pp. 705, 743. 6 Compt. Rend., vol. 146, 1908, p. 213. 1 See W. C. Brbgger, Zeitschr. Kryst. Min., vol. 16, 1890, pp. 223 et seq. 8 See G. J. Brush and E. S. Dana, Am. Jour. Sci., 3d ser., vol. 20, 1830, p. 266. 9 A variety of sodalite containing some sulphur has been named hackmannite by L. H. BorgstrCm, Zeitschr. Kryst. Min., voL 37, 1903, p. 284. A sodalite from Monte Somma containing molybdenum Is described by F. Zambonini, Mineralogia Vesuviana, p. 214, under the name molybdosodalite. 374 THE DATA OF GEOCHEMISTRY. 563.6. Specific gravity, 2.4 to 2.5. Molecular volume, 230. Color, blue, green, red, or yellow. Hardness, 5.5 to 6. Noselite or nosean. — Isometric. Composition like haiiynite, but without calcium, Al 3 Na 5 SSi 3 0 16 . Molecular weight, 569.5. Specific gravity, 2.25 to 2.4. Molecular volume, 242. Color, gray, bluish, or brownish. Hardness, 5.5. Chemically, these four minerals, together with lapis lazuli and the rarer microsommite, are to be classed as derivatives of nephelite with which they are commonly associated. Their exact composition is still somewhat uncertain. The formula assigned to cancrinite is that developed by F. W. Clarke ; 1 the three isometric species are written as interpreted by W. C. Brogger and H. Backstrom, 2 who have shown their relationship to the garnet group. Under sodalite, however, more than one compound may be included, as the experi- ments of J. Lemberg 3 and S. J. Thugutt 4 seem to indicate. The two last-named authorities regard these minerals as double molecular compounds of a silicate like nephelite with sodium carbonate, chlo- ride, sulphate, etc. In support of this view Thugutt prepared a large number of artificial compounds in which the sodium chloride of soda- lite was replaced by other salts ; but the new substances differed from the natural minerals in containing water of crystallization. 5 A dis- cussion of these salts, however, would lead us too far afield. An artificial cancrinite was obtained by Lemberg 6 when alumina, sodium silicate, and sodium carbonate solution were heated together under pressure; and also by the action of sodium carbonate, fused in its water of crystallization, upon elseolite. 7 Labradorite, heated to 215° with sodium carbonate solution, also gave him cancrinite. 8 C. and G. Friedel 9 prepared a hydrous cancrinite by heating muscovite to 500° in a solution of sodium carbonate and caustic soda. With sodium sulphate in place of the carbonate, a hydrous noselite was formed. 10 The same authors obtained sodalite by treating muscovite at 500° with sodium chloride and caustic soda. 11 Lemberg 12 produced sodalite by fusing nephelite with common salt; and the fusion of elaeolite or sodalite with sodium sulphate gave noselite. 13 In short, 1 Bull. U. S. Geol. Survey No. 588, 1914, p. 27. 2 Zeitschr. Kryst. Min., vol. 18, 1891, p. 209. 2 Zeitschr. Deutsch. geol. Gesell., vol. 37, 1885, p. 969. * Mineralchemische Studien, Dorpat, 1891. 6 A '‘chromate sodalite,” containing Na 2 Cr 04 , has lately been described by Z. Weyberg, Centralbl. Min. Geol. u. Pal., 1904, p. 727. It differs from the hydrated compound prepared by Thugutt. « Zeitschr. Deutsch. geol. Gesell., vol. 35, 1883, p. 593. 7 Idem, vol. 37, 1887, p. 963. 8 Idem, vol. 39, 1887, p. 559. For a recent discussion of the constitution of cancrinite see Thugutt, Neues Jahrb., 1911, Band 1, p. 25. 9 Bull. Soc. min., vol. 14, 1891, p. 71. w Idem, vol. 13, 1890, p. 238. n Compt. Rend., vol. 110, 1890, p. 1170. 11 Zeitschr. Deutsch. geol. Gesell., vol. 28, 1876, p. 602. » Idem, vol. 35, 1883, p. 590. ROCK-FORMING MINERALS. 375 the experiments of Lemberg, which were very numerous, proved that compounds of this class could be derived, by simple reactions, from nephelite, and that they are mutually convertible, one into another. Furthermore, S. J. Thugutt 1 prepared sodalite by heating natrolite with soda solution and aluminum chloride to 195° under pressure; and also from similar treatment of kaolin with common salt and caus- tic soda at about 212°. 2 Sodalite, then, has been derived by artificial means from elseolite, muscovite, and kaolin. It was also obtained by Z. Weyberg 3 when a mixture of silica, alumina, and soda was fused with a large excess of common salt. In his work upon artificial magmas, J. Morozewicz 4 prepared noselite, hauynite, and sodalite by purely pyrochemical methods, equivalent to those which produce these minerals in volcanic rocks. The fusions were effected at temperatures not exceeding 600° to 700°, for compounds of this class are decomposed by an excessive heat. From a mixture of kaolin, sodium carbonate, and sodium sulphate, noselite crystals were formed. From a more complex mixture, containing also calcium silicate, potassium silicate, iron silicate, calcium carbonate, and calcium sulphate, hauynite was produced. Kaolin fused with sodium carbonate and sodium chloride gave a com- pound having the formula already assigned to sodalite; elaBolite, similarly treated, yielded a substance richer in chlorine. Moro- zewicz concludes that two kinds of sodalite exist; to one he gives the formula 2(Na 2 Al 2 Si 2 0 8 ) +NaCl, while the other agrees with 3(Na 2 Al 2 Si 2 0 8 )+2NaCl. Cancrinite occurs only in elaeolite syenite and allied rocks, closely associated with nephelite and sodalite. W. Ramsay and E. T. Nyholm 5 have described a cancrinite syenite in which cancrinite is an important primary mineral. Cancrinite alters into a zeolitic sub- stance, “spreustein,” in which natrolite is the predominating mineral. 6 Crystallized sodalite is also found in trachyte and phonolites, in which it separates after augite. 7 Sodalite alters into hydronephelite and natrolite. Hauynite and noselite form in various leucitic and nephilinic rocks among the younger eruptives. In order of deposition they are the oldest of the feldspathoids. iNeues Jahrb., Beil. Band 9, 1894-95, p. 576. 2 Mineialchemische Studien, p. 18. 8 Centralbl. Min., Geol. u. Pal., 1905, p. 717. « Min. pet. Mitt., vol. 18, 1898, pp. 128-147. 6 Bull. Comm. geol. Finland, vol. 1,1895, No. 1. See also I. G. Sundell, idem, 1905, No. 16. 6 See W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1890, p. 240; also L. Saemannand F. Pisani, Annales chim. phys. , 3d ser. , vol. 67, 1863, p. 350. 7 On sodalite syenite from Square Butte, Montana, see W. Lindgren, Am. Jour. Sci.,3d ser., vol. 45, 1893, p. 286. A sodalite trachyte from Teneriffe has been described by H. Preiswerk, Centralbl. Min., Geol. u. Pal., 1909, p. 393. 878 THE DATA OF GEOCHEMISTRY. THE PYROXENES. Enstatite. — Orthorhombic. Composition, MgSi0 3 , but generally with admixtures of FeSiO s . When 10 to 12 per cent of the latter salt is present the mineral is known as bronzite. Minimum molecular weight, 100.8. Specific gravity, 3.1. Molecular volume, 32.5. Color ranging from white to olive green and brown. Hardness, 5.5. Hypersthene. — Orthorhombic. Composition like enstatite, but with FeSi0 3 predominating. The molecular weight of the latter compound is 132.3. Color, greenish and brownish to black. Specific gravity, 3.4 to 3.5. Hardness, 5 to 6. Enstatite and hypersthene, the orthorhombic members of the pyroxene group, are to be regarded as mixtures of the two isomor- phous salts MgSi0 3 and FeSiO s . Hypersthene is also modified in many cases by the presence of a third salt, CaSi0 3 , but in very subor- dinate quantities. The enstatite of the Bishopville meteorite consists of the magnesian silicate very nearly pure. The formulae given above are minima, the actual formulae being multiples of them, at least double, possibly more. The first synthesis of supposed enstatite was made by J. J. Ebel- men, 1 who fused silica, magnesia, and boric oxide together. A. Daubree 2 obtained it repeatedly in his attempts to reproduce the characteristics of meteorites, when meteoric stones and magnesian eruptive rocks were fused. 11 Enstatite” recrystallized on cooling the melts. He also prepared the same substance by fusing olivine with silica, and he found that when serpentine was melted it broke down into a mixture of enstatite and olivine. The latter reaction has been verified quantitatively in the laboratory of the United States Geological Survey. P. Hautefeuille 3 produced a silicate which he identified with enstatite, by dissolving amorphous silica in molten magnesium chloride, and S. Meunier 4 * effected its synthesis by acting on metallic magnesium with silicon chloride and water vapor. Later investigations, however, by F. Fouque and A. Michel Levy, 6 and also by J. H. L. Vogt, 6 have shown that the foregoing syntheses were misinterpreted. The product obtained was in most cases, if not in all, a monoclinic magnesium metasilicate, instead of the orthorhombic enstatite. The latter form was obtained by Fouque and Levy 7 by simply fusing silica, magnesia, and ferric oxide together, but it was more or less mixed with the monoclinic variety. lAnnales chim. phys., 3d ser., vol. 33, 1851, p. 58. iCompt. Rend., vol. 62, 1866, pp. 20C, 369, 660. « Annales chim. phys., 4th ser., vol. 4, 1865, p. 174. « Compt. Rend., vol. 90, 1880, p. 349; vol. 93, 1881, p. 737. 6 Synthase des mindraux et des roches, 1882. c Mineralbildung in Schmeizmassen, 1892, p. 71. 7 Loc. clt. ROCK-FORMING MINERALS. 877 In the elaborate research by E. T. Allen, F. E. Wright, and J. K. Clement, 1 it has been found that magnesium metasilicate exists in four modifications, two being pyroxenes and two amphiboles. The monoclinic pyroxene is formed whenever a melt having its composi- tion is allowed to crystallize at temperatures a little below 1,521°. It can be crystallized at lower temperatures from solution in molten calcium vanadate, magnesium vanadate, or magnesium tellurite. The other three modifications of the silicate pass into this variety when heated to about 1,000° in molten magnesium chloride trav- ersed by a stream of dry hydrochloric acid gas. The monoclinic pyroxene, then, is the most stable form of magnesium metasilicate. According to N. L. Bowen and O. Andersen, 2 it has no true melting point but breaks down at 1,557° into forsterite and silica. When a glass having the composition of enstatite is devitrified by heating to a temperature above 1,000° and below 1,100°, best at about 1,075°, the orthorhombic enstatite is formed. In this way good crystals were produced. At slightly higher temperatures the monoclinic pyroxene begins to appear. The presence of enstatite in an igneous rock is evidence that the final crystallization took place at the relatively lower temperatures, for above them it can not exist. What the effect of iron may be in modifying the properties of these silicates is as yet undetermined. Enstatite and hypersthene are common pyrogenic minerals, and occur in many eruptive rocks. Enstatite and bronzite are often con- stituents of meteorites. According to J. Morozewicz 3 the ortho- rhombic pyroxenes separate from metasilicate magmas when the ratio Mg + Fe:Ca.is 3:1 or greater. Both species undergo altera- tion, through hydration, into talc 4 and serpentine. Bastite is an alteration product of this kind, having the composition of serpentine. Wollastonite. — Monoclinic. Composition, CaSi0 3 . Minimum mo- lecular weight, 116.5. Specific gravity, 2.85. Molecular volume, 40.5. Color, white, often tinted by impurity. Hardness, 4.5 to 5. Calcium metasilicate is known in two modifications — the natural wollastonite and an artificial pseudohexagonal form. The latter is easily produced by fusing lime and silica together 5 and has been repeatedly observed in slags. 6 Wollastonite has also been found in slags, but rarely. 7 E. Hussak, 8 however, by fusing and slowly cool- ing a glass containing silica, soda, lime, and boric acid, obtained 1 Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 385. 2 Idem, vol. 37, 1914, p. 487. s Min. pet. Mitt., vol. 18, 1898, p. 110. « See C. H. Smyth, School of Mines Quart., vol. 17, 1896, p. 333. c See L. Bourgeois, Bull. Soc. min., vol. 5, 1882, p. 13; A. Gorgeu, idem, vol. 10, 1S87, p. 273; and C. Doel- ter, Neues Jahrb., 1886, Band 1, p. 119. c See J. H. L. Vogt, Mineralbildung in Schmelzmassen, 1892, pp. 34-80. i See Vogt, loc. cit., and P. Heberdey, Zeitschr. Kryst. Min., vol. 26, 1896, p. 22. a Zeitschr. Kryst. Min., vol. 17, 1890, p. 101. 378 THE DATA OF GEOCHEMISTRY. crystals of wollastonite. C. Doelter 1 also effected the synthesis of wollastonite by fusing calcium metasilicate with sodium fluoride. According to E. T. Allen and W. P. White, 2 wollastonite is stable only below 1,190°, and above that temperature it passes into the pseudohexagon al modification. By heating a glass of the composi- tion CaSi0 3 to between 800° and 1,000°, pure wollastonite was obtained. The reverse change, from the pseudo variety to the normal, was brought about by dissolving the former in molten cal- cium vanadate and crystallizing at a temperature between 800° and 900°. The melting point of the silicate is 1,540°. The pseudowoflastonite has not yet been observed as a natural mineral, but wollastonite is common. The inference from this fact, as drawn by G. F. Becker, 3 is that the rocks containing free calcium metasilicate must have crystallized at temperatures below the inver- sion point of wollastonite, for otherwise its isomer would have appeared. Although wollastonite is usually classed with the pyroxenes, its place among them is doubtful. It differs from them in being easily decomposed by acids, and its occurrences in nature are not the same. It is very rare in eruptive rocks, and is commonly found as a product of contact metamorphism, especially in limestones. It occurs also in feldspathic schists. H. Wulf 4 has described a rock from Hereroland, Africa, which consisted of wollastonite and diopside in nearly equal proportions. An occurrence of wollastonite in aplite is recorded by A. Lacroix. 5 The alteration of wollastonite to ordinary pyroxene is reported by C. H. Smyth, 6 and an alteration to apophyflite by S. J. Thugutt. 7 The secondary mineral pectolite, HNaCa 2 Si 3 0 9 , is regarded as a derivative of wollastonite. Diopside. — Monoclinic. Composition, CaMgSi 2 0 6 . Molecular weight, 217.3. Specific gravity, 3.2. Molecular volume, 68. Color, white, yellowish, green, and nearly black. Hardness, 5 to 6. Chrome diopside is a variety containing small amounts of chromium. Hedenbergite. — Monoclinic. Composition, CaFeSi 2 0 6 . Molecular weight, 248.8. Specific gravity, 3.5 to 3.6. Molecular volume, 70. Color, grayish green to black. Hardness, 5 to 6. Between diopside and hedenbergite there are various intermediate mixtures. Schefferite is another monoclinic pyroxene containing 1 Min. pet. Mitt., vol. 10, 1888, p. 83. For later work by Doelter, see Sitzungsb. K. Akad. Wiss. Wien, yoI. 120, Abth. 1, p. 339, 1911. 2 Am. Jour. Sci., 4th ser., vol. 21, 1906, p. 89. See also A. L. Day, E. S. Shepherd, and F. E. Wright, idem, vol. 22, p. 265. The synthetic wollastonite reported by L. v. Szathm&ry (Foldt. Kozl., vol. 39, 1909, p. 314) was the pseudomineral. See B. Mauritz, idem, p. 505. 3 Prefatory note to the memoir by Allen and White. * Min. pet. Mitt., vol. 8, 1887, p. 230. 3 Bull. Soc. min., vol. 21, p. 272, 1898. c Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 309. 7 Centralbl. Min., Geol. u. Pal., 1911, p. 764. ROCK-FORMING MINERALS. 879 manganese, up to over 8 per cent of MnO. Jeffersonite is another member of this group containing zinc. These variations may repre- sent mixtures of the simple salts MnSi0 3 and ZnSi0 3 with the lime, magnesia, and iron silicates; but the commingled salts are probably more complex. Rhodonite, MnSiO s , is classed also as a pyroxene, but is triclinic. It can hardly be considered as a rock-forming min- eral, at least not in the usual acceptance of the term. Monoclinic pyroxenes of the diopside-hedenbergite type have been repeatedly observed in slags. 1 A. Daubree, 2 on heating water to incipient redness in a glass tube, obtained crystals of diopside. G. Lechartier 3 effected the synthesis of these pyroxenes by fusing silica, lime, and magnesia with an excess of calcium chloride. When ferric oxide was added to the mixture, iron pyroxenes were formed. In the experiments of J. Morozewicz 4 with artificial magmas these min- erals were deposited when the ratio Mg + Fe:Ca was less than 3:1. Clear and perfect crystals of diopside have been prepared by E. T. Allen and W. P. White, 5 who heated glass of the theoretical composi- tion in a flux of calcium chloride and an atmosphere of hydrochloric acid to 1,000° for several weeks. The specific gravity of the artificial mineral was 3.275 and the melting point 1,380°. They found that diopside is the only stable compound between its component silicates, although two eutectics were observed. The monoclinic pyroxenes are common in eruptive rocks and the crystalline schists. The variety known as diallage is especially characteristic of gabbro. They also occur as secondary minerals. R. Brauns 6 has observed the variety salite, as formed in a picrite by the action of aqueous solutions upon olivine and plagioclase. Acmite or segirite. — Monoclinic. Normally NaFe ,// Si 2 0 6 , but often containing ferrous and lime silicates in isomorphous admixture. Molecular weight, 231.7. Specific gravity, 3.53. Molecular volume, 65.6. Color, brownish, greenish, to black. Hardness, 6 to 6.5. Jadeite. — Monoclinic. Composition, NaAlSi 2 0 6 . Molecular weight, 202.9. Specific gravity, 3.34. Molecular volume, 60.8. Color, white and- various shades of green. Hardness, 6.5 to 7. Spodumene. — Monoclinic. Composition, LiAlSi 2 O c . Molecular weight, 186.9. Specific gravity, 3.17. Molecular volume, 58.9. Color, white, yellow, green, and amethystine. Hardness, 6.5 to 7. Hiddenite is the emerald-green gem spodumene from North Carolina. Kunzite is the amethystine gem variety from California. 1 See citations in L. Bourgeois, Reproduction artiflcielle des min4raux, pp. 115-116; and Fouqu4 and L4vy, Synthase des min4raux et des roches, pp. 102-103. Also G. J. Brush, Am. Jour. Sci., 2d ser., vol. 39, 1865, p. 13i 3 Etudes synth4tiques de geologie exp4rimentale, pp. 159-176. 8 Compt. Rend., vol. 67, 1868, p. 41. Compare A. Gorgeu, Bull. Soc. min., vol. 10, 1887, pp. 273, 276. 4 Min. pet. Mitt., vol. 18, 1898, pp. 123 et seq. See also J. H. L. Vogt, Die Silikatschmelzlosungen, pt. 1, 1903, pp. 28-49. & Am. Jour. Sci., 4th ser., vol. 27, 1909, p. 1. o Nenes Jahrb., 1898, Band 2, p. 79. 380 THE DATA OF GEOCHEMISTRY. These alkali pyroxenes, as they are often called, are interesting on account of their constitutional similarity. Acmite, however, is the most important as a rock-forming mineral, although in the inter- pretation of mixed pyroxenes the jadeite molecule must often be taken into account. Spodumene occurs only sporadically — usually, if not always, in pegmatite — and is peculiarly noticeable on account of the immense size which its crystals may attain. Crystalline faces of spodumene many feet in length have been observed in the Black Hills of South Dakota. The alteration of spodumene, as studied by A. A. Julien, 1 and more exhaustively by G. J. Brush and E. S. Dana, 2 is very instructive. First, by the action of percolating solutions con- taining soda, it is transformed into a mixture of eucryptite, LiAlSi0 4 , and albite, NaAlSi 3 0 8 . Then, by the further action of potassium salts, the eucryptite i3 altered into muscovite, KH 2 Al 3 Si 3 0 12 . Albite and muscovite are the final products of these metamorphoses. The intimate mixture of these two compounds was long thought to be a distinct mineral, cymatolite. Acmite can be produced synthetically, but its constituent oxides, when fused together, commonly yield only a glass containing crystals of magnetite. Acmite, when fused, resolidifies as a mixture of mag- netite and glass. 3 C. Doelter, 4 * however, from the fusion of an arti- ficial mixture of the oxides, obtained some acmite. H. Backstrom 6 fused silica, ferric oxide, and sodium carbonate, mingled in the proper proportions, together and held the solidified mixture at a dull red heat for three days. Under those conditions acmite was formed. He also obtained it by fusing a leucite phonolite and subjecting the glass to a similar, very slow devitrification. Z. Weyberg 6 also ob- tained acmite by fusing a mixture of the composition 2Si0 2 + Fe 2 0 8 + Na 2 0 with a large excess of sodium chloride. According to J. Moro- zewicz, 7 the acmite-j adeite compounds form in metasilicate magmas when the silica amounts to less than 50 per cent. The exact condi- tions of their generation, however, with respect to temperature and rate of cooling, are yet to be determined. Several attempts have been made toward the synthesis of spodu- mene. By fusing together lithium carbonate, alumina and silica K. Ballo and E. Dittler 8 obtained several silicates, one having the com- position of spodumene, and another that of eucryptite. The artificial spodumene, however, differs from the natural mineral in its optical properties, and is designated /? spodumene. The natural, a mineral 1 Annals New York Acad. Sci., vol. 1, 1879, p. 318. 2 Am. Jour. Sci., 3d ser., vol. 20, 1880, p. 257. * M. Vu6nik, Centralbl. Min., Geol. u. Pal., 1904, p. 369. * Neues Jahrb., 1897, Band 1, p. 16. 8 Bull. Soc. min., vol. 16, 1893, p. 130. 8 Centralbl. Min., Geol. u. Pal., 1905, p. 717. 7 Min. pet. Mitt., vol. 18, 1898, p. 123. 8 Zeitschr. anorg. Chemie, vol. 76, 1912, p. 39. BOCK-FORMING MINERALS. 381 is transformed at about 1,000° into the other, which melts at 1,380°. Similar results have since been obtained by F. M. Jaeger and A. Simek, 1 who found the transition temperature from a to $ spodumene to be 995°, and the melting point 1,417°. Natural kunzite fused at 1,428°, and the artificial orthosilicate, a pseudoeucryptite ” at 1,388°. Acmite is a mineral of eruptive rocks, generally of those which contain leucite or nephelite. It is especially common in elseolite syenite. Concerning the petrologic relations of jadeite less is known; but S. Franchi 2 has identified the mineral as an essential constituent of certain eruptive rocks in Piedmont. Acmite or segirite, according to W. C. Brogger, 3 alters into analcite. J. Lemberg, 4 by heating spodumene or jadeite with alkaline solutions under pressure, also obtained analcite. Jadeite alone is slowly attacked, but the glass resulting from its fusion is altered readily. It is noticeable that jadeite and dehydrated analcite have the same empirical composition; but the denser jadeite molecule is doubtless the more complex. The one is a polymer of the other. These alterations, natural or artificial, emphasize the constitutional similarity of the three alkali pyroxenes. Augite. — Monoclinic. Composition very variable, for augite is an isomorphous mixture of several different silicates. Specific gravity, 2.93 to 3.49. Color, white, green, brown, and black. Hardness, 5 to 6. Augite is essentially a metasilicate of lime, magnesia, and ferrous iron, plus silicates of ferric iron and alumina. Manganese and alkalies are often present, and some varieties contain titanic oxide up to 4.5 per cent. In addition to silicate molecules analogous to those of the pyroxenes already described, augite is supposed to con- tain a compound of the form R/'Al 2 Si0 6 , which, however, is hypo- thetical. The rare mineral komerupine or prismatine, however, has the formula MgAl 2 Si0 6 , and may represent the aluminous con- stituent of the nonalkaline augites. 5 6 When alkalies are present they probably represent molecules analogous to or identical with acmite and jadeite. 1 Abst.in Chem. Zentralbl., 1914, ii, pp. 1026, 1027. See also K. Endell and R. Rieke, Zeitschr. anorg. Chemie, vol. 74, 1912, p. 33; who give 950° as the melting point of natural spodumene. For an earlier research on the lithium-aluminum silicates see P. Hautefeuille, Compt. Rend., vol. 90, 1880, p. 541. 2 Rendiconti R. accad. Lincei, vol. 9, pt. 1, 1900, p. 349. On the jadeite of Upper Burma, see A. W. G. Bleeck, Zeitschr. prakt. Geologie, 1907, p. 341. s Zeitschr. Kryst. Min., vol. 16, 1890, p. 333. Brogger cites many references to the literature of acmite. < Zeitschr. Deutsch. geol. Gesell., vol. 39, 1887, p. 584. 6 A more complex formula, NaHsMgeAlwSbO^, has been assigned to kornerupine by J. Uhlig, Zeitschr. Kryst. Min., vol. 47, 1910, p. 215. 382 THE DATA OF GEOCHEMISTRY. The following analyses of rock-forming augite 1 were all made in the laboratory of the United States Geological Survey: Analyses of augite. A. From nepheline basalt, Black Mountain, Uvalde quadrangle, Texas. W. F. Hillebrand, analyst. B. From dolerite, near Valmont, Colorado. Analyzed by L. G. Eakins. C. From tinguaite, Two Buttes, Colorado. Analyzed by Hillebrand. D. From granite, Silver Cliff, Colorado. Eakins, analyst. E. From a dyke, Silver Cliff. Eakins, analyst. F. From basalt, Mount Taylor region, New Mexico. Analyzed by T. M. Chatard. A B c D E F Si0 2 45. 23 49.10 47. 54 48. 72 54.87 47. 06 Ti0 2 4. 28 3.00 1. 82 7. 73 7. 95 4. 14 9. 27 6. 34 7. 77 CrK Trace. Trace. 1. 30 Fe 2 0 3 2. 95 5. 64 3. 77 2. 88 FeO 4. 07 8. 30 6. 42 6.34 4. 61 8. 15 MnO . 07 .36 .34 .14 .20 MgO 12. 25 12.37 10. 05 14. 67 14. 47 13. 52 CaO : 23. 37 22. 54 21. 57 16. 79 15. 87 19. 33 Na 2 0 .47 Trace.. 1. 38 .19 .28 .33 K 2 0 .12 Trace. . 12 .11 NiO .05 Trace. Trace. F oOe None. .06 .37 .18 .31 .20 2 V 100. 96 100. 26 100. 22 100. 27 99. 77 99. 85 Augite is a common mineral in slags, 2 and is easily produced from its constituents by simple fusion. 3 It was repeatedly obtained by Fouque and Levy, 4 both by itself and in association with other miner- als, in their classic experiments upon the synthesis of rocks. J. Morozewicz 5 also has found both ordinary augite and the alkaline varieties in the products yielded by his artificial magmas. The mole- cule RAl 2 Si0 6 is generally formed from magmas containing over 50 per cent of silica; and its alumina appears to be the residue left over after the feldspars, feldspathoids, and micas have been satisfied. When garnet, vesuvianite, or epidote is fused augitic minerals appear among the compounds produced. 6 Biotite and clinochlore also yield it among the products of their thermal decomposition. 7 C. Doelter 8 found that augite was formed when diopside was fused with alumina or ferric oxide; and from mixtures of silica with the proper bases he obtained crystals rich in RAl 2 Si0 6 . According to J. Lenarcic, 9 magnetite and labradorite, fused together, yield augite. 1 From Bull. U. S. Geol. Survey No. 419, 1910, pp. 262, 263. 2 See J. H. L. Vogt, Mineralbildung in Schmelzmassen, p. 34. 8 For early syntheses, see Fouqu6 and Levy, Synthese des min^raux et des roches, p. 102. 3 , associated with the fayalite of Rockport, Massachusetts, has been described by C. H. Warren, Am. Jour. Sci., 4th ser., vol. 16, 1903, p. 337. 384 THE DATA OF GEOCHEMISTRY. Adinolite . — Like tremolite, but with iron partly replacing mag- nesium. Specific gravity, 3 to 3.2. Nephrite is a compact variety of actinolite. True asbestos is a fibrous form of tremolite or actinolite; but anthophyllite and crocidolite are also found asbestiform. The Canadian asbestos of commerce is serpentine. 1 Cummingtonite. — Monoclinic, but with the composition of an anthophyllite containing much iron. Specific gravity, 3.1 to 3.3. Color, gray to brown. The foregoing members of the amphibole group, except the alumi- nous gedrite, are most simply interpreted, like the corresponding pyroxenes, as mixtures of metasilicates of calcium, magnesium, and iron. Griinerite is the ferrous silicate, FeSiO a alone. 2 Dannemorite is a similar iron-manganese metasilicate. In richterite, which has a similar general formula, alkalies appear, up to 9 per cent or more. Many analyses of these minerals show the presence of water in them, and also of fluorine. Anthophyllite and gedrite are essentially Archean minerals, occur- ring especially in hornblende gneisses and schists. Tremolite is found as an accessory mineral in metamorphic limestones and dolomites. Actinolite is also a mineral of the metamorphic rocks. In the iron regions near Lake Superior actinolite-magnetite schists are common. 3 Anthophyllite, tremolite, and actinolite alter easily into talc, ser- pentine, and calcite. The reverse alteration, of talc into anthophyl- lite, has been reported by Genth. 4 Uralite, which has ordinarily the composition of actinolite, is an amphibole derived by alteration from similarly constituted pyroxenes. 5 Hornblende. — Monoclinic. Composition variable, as with augite, of which hornblende is the equivalent among the amphiboles. Horn- blende, however, contains a smaller proportion of lime and more magnesia plus iron than augite. It also contains aluminous silicates. The fight-colored hornblende, with little iron, is called edenite. The darker varieties are known as pargasite. Specific gravity, 3.0 to 3.47, depending upon the proportion of iron. Color, white, gray, green, and brown, ranging to black. Hardness, 5 to 6. The subjoined analyses of hornblende are given in the memoir by S. L. Penfield and F. C. Stanley. 6 They show the variability in com- position of the mineral, and also the predominance of magnesium and iron over calcium, the reverse condition from that noted in augite. i See G. P. Merrill, Proc. U. S. Nat. Mus., vol. 18, 1896, p. 281, for a good summary of our knowledge of asbestos. * A. C. Lane and F. F. Sharpless (Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 505) have applied the name griinerite to a ferromagnesian amphibole like cummingtonite. a See W. S. Bayley, Am. Jour. Sci., 3d ser., vol. 46, 1893, p. 176. Also C. R. Van Hise, C. K. Leith, and others, in Mon. U. S. Geol. Survey, vol. 28, 1897; vol. 43, 1903. * Proc. Am. Philos. Soc., vol. 20, 1882, p. 393. 6 On the theory of uralitization see L. Duparc and T. Homung, Compt. Rend., vol. 139, 1904, p. 223. See also Duparc, Bull. Soc. min., vol. 31, 1908, p. 50. 6 Am. Jour. Sci., 4th ser. # vol. 23, 1907, p. 23. ROCK-FORMING MINERALS, 385 Analyses of hornblende. A. From Renfrew, Ontario. Stanley, analyst. B. From Edenville, New York. Stanley, analyst. C. From Cornwall, New York. J. L. Nelson, analyst. Am . Jour. Sci., 4th ser., vol. 15, 1903, p. 227. Fluorine determination added to Nelson's analysis by Stanley. D. From Monte Somma, Italy. Stanley, analyst. E. Basaltic hornblende, Bilin, Bohemia. Stanley, analyst. F. From Grenville Township, Quebec. Stanley, analyst. A B C D E F SiOo 43. 76 41. 99 36. 86 39. 48 39. 95 45. 79 Ti0 2 .78 1.46 1.04 .30 1. 68 1.20 A1 2 0 3 8. 33 11. 62 12. 10 12. 99 17. 58 11.37 Fe 2 0 3 6. 90 2. 67 7. 41 7. 25 7.25 .42 FeO 10. 47 14. 32 23.35 10. 73 2. 18 .42 MnO .50 .25 . 77 1.00 Trace. .39 MgO 12. 63 11. 17 1.90 11.47 14. 15 21. 11 CaO 9. 84 11. 52 10. 59 12. 01 11. 96 12. 71 K 2 0 1. 28 .98 3.20 2.39 1. 98 1. 69 Na 2 0 3. 43 2. 49 1.20 1. 70 3. 16 2. 51 H 2 0 .65 .61 1.30 .76 .41 . 67 F 1. 82 .80 .27 .05 .03 2. 76 Loss at 110° .10 .08 .12 .13 0=F 100. 49 .76 99. 96 .33 99. 99 .11 100. 25 .02 100. 46 .01 101. 04 1. 16 99.73 99. 63 99. 88 100. 23 100. 45 99. 88 The synthesis of hornblende was first effected by K. Chrustschoff. 1 He heated a solution containing dialyzed silica, alumina, and ferric hydroxide, with some ferrous hydroxide, magnesium hydroxide, and limewater, for three months to 550° in a closed digester, and obtained crystals of amphibole. C. Doelter, 2 by using fluxes of low melting point, also succeeded in producing the mineral. A mixture of mag- nesia, oxide of iron, alumina, and silica, fused with boric acid, gave the desired result. He also succeeded in recrystallizing amphiboles from a flux of borax, or from one of magnesium chloride and calcium chloride; but in most of his experiments augite, sometimes with olivine, scapolite, magnetite, anorthite, or orthoclase, was produced. E. T. Allen, F. E. Wright, and J. K. Clement, 3 in the research already cited under pyroxene, found that when magnesium metasilicate was heated considerably above its melting point and then rapidly cooled, the orthorhombic amphibole was formed. With slow cooling, pyrox- enes are produced. By heating the orthorhombic amphibole with water at 375° to 475°, it was transformed into the monoclinic modi- fication. The latter was also obtained when solutions of magnesium ammonium chloride or of magnesium chloride and sodium bicarbonate 1 Compt. Rend., vol. 112, 1891, p. 677. 2 Neues Jahrb., 1897, Band 1, p. 1. 3 Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 385. 97270°— Bull. 616—16 25 386 THE DATA OF GEOCHEMISTRY. were heated with sodium silicate or amorphous silica during three to six days at 375° to 475° in a steel bomb. Small quantities of quartz and of forsterite were formed at the same time. According to A. Becker, 1 when anthophyllite or hornblende is fused, a pyroxene, sometimes with olivine, is formed. According to A. Lacroix, 2 alterations, due to heat alone or to the action of molten magmas, of hornblende to augite, are common among the volcanic rocks of Auvergne. The amphiboles, in short, are unstable at high temperatures, and either the rapid cooling of a magma, the presence of water, or some undetermined influences of pressure, conditions their appearance as pyrogenic minerals. An excess of magnesia is also favorable to their development, while an excess of lime may determine the formation of pyroxene. Common hornblende is very widely diffused, as in granite, syenite, diorite, diabase, gabbro, and norite, and in the metamorphic gneisses, hornblende schists, and amphibolites. The crystallized “basaltic hornblende” appears as an early secretion in andesite, dacite, phono- lite, basalt, etc. Hornblende alters, not only into pyroxenes as men- tioned above, but also into chlorite, epidote, biotite, siderite, calcite, and quartz. Pseudomorphs of hornblende or of anthophyllite after olivine have been described by F. Becke 3 and B. Kolenko. 4 * Ordinarily, the constitution of the hornblendes is supposed to be analogous to that of augite, metasilicates of the form RSi0 3 being isomorphously commingled with Tschermak’s hypothetical compound, RAl 2 Si0 6 . It is also commonly assumed that the amphibole mole- cules are larger than those of the pyroxenes, as shown by the formulae of diopside, MgCaSi 2 0 6 , and tremolite, CaMg 3 Si 4 0 12 . The latter assumption, however, is not well grounded, for the amphiboles, as a rule, are lower in specific gravity than the corresponding pyroxenes, which indicates that their molecules are really less condensed. The true molecular weights are unknown; and it is quite possible that they are better represented by polymeric symbols, such as R 8 Si 8 0 24 in the pyroxene series and R 4 Si 4 0 12 for the amphiboles. The way in which the alkali pyroxenes alter into mixtures of orthosilicates and trisilicates offers an argument in favor of this view. In fact, G. F. Becker 5 has sought to explain the relations between the two groups of minerals upon the supposition that they are mixtures of the two classes of salts just named. There are still other interpreta- tions of the hornblendes. R. Scharizer 6 regards them as mixtures of actinolite with an orthosilicate isomeric with garnet, R" 3 R"' 2 Si 3 0 12 , 1 Zeitschr. Deutsch. geol. Gesell., vol. 37, 1885, p. 10. 2 Min6ralogie de la France, vol. 1, 1893-1895, pp. 668-669. 3 Min. pet. Mitt., vol. 4, 1882, p. 450. 4 Neues Jahrb., Band 2, 1885, p. 90. 6 Am. Jour. Sci., 3d ser., vol. 38, 1889, p. 154. See also F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914. 6 Neues Jahrb., Band 2, 1884, p. 143. ROCK-FORMING MINERALS. 387 to which he has given the name “syntagmatite.” A hornblende from Jan Mayen Island agrees very nearly with the supposed syn- tagmatite in composition. F. Berwerth 1 also assumes the presence of orthosilicates in the hornblendes, and attributes part of their alumina to molecules which are either those of mic&s or isomeric with them. Another portion of the alumina he regards as forming the metasilicate Al 2 Si 3 0 9 , a compound which is not known to occur by itself in nature. An alkali hornblende from Piedmont, described by F. R. Van Horn, 2 has very nearly orthosilicate ratios; and so also has a variety from Dungannon, Ontario, studied by F. D. Adams and B. J. Harrington. 3 Some hornblendes, however, contain a larger proportion of oxygen than orthosilicates require; and to explain their constitution it is necessary to assume the existence of basic salts — a condition which is fulfilled by the molecule RAl 2 Si0 6 . The synthesis of such a compound, or its discovery as an actual mineral would go far toward settling the constitution of this important group. 4 An interpretation of the amphiboles quite unlike that of Tschermak has been proposed by S. L. Penfield and F. C. Stanley. 5 They assume the existence in them of bivalent molecules, Al 2 OF 2 , A1 2 0(0H) 2 , A1 2 0 3 R", and Al 2 0 4 R /, Na 2 , and also the univalent group MgF, in order to account for fluorine, water, and alumina. All of the amphi- boles are then formulated as polymetasilicates. All of these interpretations of the amphibole group need careful reconsideration in the light of evidence obtained by E. T. Allen and J. K. Clement. 6 These chemists find that water is an almost invaria- ble constituent of these minerals, running up in tremolite to as high as 2.5 per cent. This water is gradually lost on heating, without any loss of homogeneity and with very slight change in the optical prop- erties. It is therefore not constitutional but occluded water, or water in “ solid solution,” as the authors express it. W. T. Schaller, however, finds that the water of tremolite is essential to the meta- silicate ratio, and is therefore more probably constitutional. Glauco'phane. — Monoclinic. Normally NaAlSi 2 0 6 .(FeMg)Si0 3 , but variable amounts of the calcium metasilicate may be present also. Color, blue, bluish black, or grayish. Specific gravity, 3 to 3.1. Hardness, 6 to 6.5. 1 Sitzungsb. K. Akad. Wiss. Wien, vol. 85, pt. 1,1882, p. 153. SeealsoH. Haefcke, Doct. Diss., Gottingen, 1890. 2 Am. Geologist, vol. 21, 1898, p. 370. 2 Am. Jour. Sci., 4th ser., vol. 1, 1896, p. 210. “Hastingsite.” * According to C. Doelter and E. Dittler (Sitzungsb. K. Akad. Wiss. Wien, vol. 121, Abth. 1, 1912, p. 897), the compound MgALSiOe is unstable in fusion. A compound K 2 Al2Si0 6 has been prepared by Z. Weyberg, Centralbl. Min., Geol. u. Pal., 1911, p. 326. * Am. Jour. Sci. , 4th ser., vol. 23, 1907, p. 23. Other discussions of the constitution of the amphiboles are by S. Kreutz, Sitzungsb. K. Akad. Wiss. Wien, vol. 117, Abth. 1, 1908, p. 877, and G. Murgoci, Bull. Dept. Geology TJniv. California, vol. 4, 1906, p. 359. 6 Am. Join*. Sci., 4th ser., vol. 26, p. 101, 1908, Schaller’s criticism is as yet unpublished. 388 THE DATA OF GEOCHEMISTRY. Riebeckite. — Monoclinic. Composition, 2NaFeSi 2 0 6 .FeSi0 3 . Color, black. Crocidolite. — Composition, NaFeSi 2 0 6 .FeSi0 3 . Resembles riebeck- ite. Molecular weight, 364.1. Specific gravity, 3.2 to 3.3. Molecu- lar volume, 112. Asbestiform. Color, dark blue, sometimes greenish or nearly black. Hardness, 4. Several other amphiboles related to the three species described above have been given independent names. Rhodusite, described by H. B. Foullon, 1 is an asbestiform variety of glaucophane in which aluminum has been replaced by ferric iron. Crossite, from Cali- fornia, according to C. Palache, 2 is intermediate between riebeckite and glaucophane. Holmquistite is a glaucophane from Sweden con- taining over 2 per cent of lithia, described by A. Osann. 3 Arfvedsonite. — Monoclinic. The composition is approximately 4Na 2 Si0 3 + 13FeSi0 3 + 3CaSi0 3 + Fe // Al 2 Si0 6 , but probably variable. Specific gravity, 3.45. Color, black, Hardness, 6. Barkevikite . — Intermediate between arfvedsonite and hornblende. 4 Color, black. Specific gravity, 3.43. AEnigmatite. — Triclinic. Essentially a metasilicate of sodium and ferrous iron, but with titanium replacing a part of the silicon, and a small admixture of the basic salt RFe"' 2 Si0 6 . 5 Specific gravity, 3.80. Color, black. Among these alkali amphiboles, glaucophane and riebeckite are the most important. They are partly, although not absolutely, the equiv- alent of jadeite and acmite among the pyroxenes, but differ from them chemically in containing the molecules FeSi0 3 and MgSi0 3 in addi- tion to the aluminous compounds. None of them has been prepared synthetically, and, like the other amphiboles, they yield pyroxenes upon fusion. 6 Glaucophane occurs chiefly in a series of glaucophane schists and in eclogite. 7 It has also befen observed in some eruptive rocks. It alters into chlorite, feldspar, and hematite. 8 Riebeckite is found in gran- ites and syenites; crocidolite also occurs in granite and in quartz 1 Sitzungsb. K. Akad. Wiss. Wien, vol. 100, Abth. 1, 1891, p. 176. 2 Bull. Dept. Geology Univ. California, vol. 1, 1894, p. 181. 2 Sitzungsb. Heidelberg Akad., 1913, Abhandl. 23. * For a discussion of the composition of barkevikite, see W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1890, p. 412. For constitution of these amphiboles see F. W. Clarke, Bull. U. S. Geol. Survey No. 588, pp. 102, 103. 6 See Brogger, op. cit., pp. 428-429. See also J. Soellner, Neues Jahrb., Beil. Band 24, 1907, p. 475, who has described a new mineral, rhoenite, allied to aenigmatite. « See Brogger, op. cit., p. 410, with reference to arfvedsonite. C. Doelter (Min. pet. Mitt., vol. 10, 1888, p. 70) fused glaucophane with sodium fluoride and magnesium fluoride and obtained a product resembling acmite. 7 See K. Oebbeke, Zeitschr. Deutsch. geol. Gesell., vol. 38, 1886, p. 634, for a summary of occurrences and bibliography. Also H. S. Washington, Am. Jour. Sci., 4th ser., vol. 11, 1901, p. 35; G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, p. 102; and H. Rosenbusch, Sitzungsb. K. Akad. Wiss. Berlin, 1898, p. 706. Washington’s memoir is very full. On the glaucophane rocks of California, see J. P. Smith, Proc. Am. Philos. Soc., vol. 45, 1907, p. 183. 8 L. Colomba, Zeitschr. Kryst. Min., vol. 26, 1896, p. 215. ROCK-FORMING MINERALS. 389 schist. By oxidation of the iron and infiltration of silica, crocidolite alters into the beautiful ornamental stone known as “ tiger-eye.” Riebeckite is reported as altering to epidote. 1 Arfvedsonite and barkevikite occur chiefly in augite and elseolite syenites, also in a granite. iEnigmatite is known chiefly from the sodalite syenite of Greenland; but cossyrite, which is probably the same mineral, was found in a rhyolite lava. Arfvedsonite alters into acmite and lepidomelane, 2 and so also does barkevikite. 3 Kaersutite from Greenland and linosite from the island of Linosa, east of Tunis, are aluminous amphiboles rich in titanium. In lin- osite H. S. Washington 4 found over 10 per cent of Ti0 2 . THE O El VINE GROUP. Forsterite. — Orthorhombic. Composition, Mg 2 Si0 4 . Molecular weight, 141.4. Specific gravity, 3.2. Molecular volume, 44.2. Color, white, often tinted yellowish, greenish, or gray. Hardness, 6 to 7. Melting point, 1,890°, Bowen. Fayalite. — Orthorhombic. Composition, Fe 2 Si0 4 . Molecular weight, 204.4. Specific gravity, 4 to 4.14. Molecular volume, 49.8. Color, yellow to brown and black. Hardness, 6.5. Forsterite and fayalite are two minerals which, rare by themselves, are very common in isomorphous mixture. The usual mixture, in which the magnesium salt predominates, is known as olivine, chryso- lite, or peridot. A variety containing a large amount of iron is called hyalosiderite. Hortonolite is another member of the group, contain- ing much iron, less magnesia, and about 4.5 per cent of manganese oxide. The compound Mn 2 Si0 4 occurs as tephroite, and roepperite is a variety containing zinc. Knebelite is intermediate between fayalite and tephroite. All of these minerals are represented by the general orthosilicate formula R 2 Si0 4 . Titanic oxide, up to 5 per cent or more, may replace a part of the silica in olivine, forming a variety to which the name titanolivine has been given. 5 Monticellite. — Orthorhombic. Composition, MgCaSi0 4 . Molecu- lar weight, 188.9. Specific gravity, 3 to 3.25. Molecular volume, 61. Colorless to yellowish, greenish, or gray. Hardness, 5 to 5.5. The very rare glaucochroite, CaMnSi0 4 , is analogous to monticellite in composition. 1 On riebeckite rocks, see G. T. Prior, Mineralog. Mag., vol. 12, 1889, p. 92; P. Termier, Bull. Soc. min., vol. 27, 1904, p. 265; G. M. Murgoci, Am. Jour. Sci., 4th ser., vol. 20, 1905, p. 133. According to Murgoci, riebeckite forms only from persilicic magmas. Riebeckite rocks from Oklahoma are described by A. F. Rogers in Jour. Geology, vol. 15, 1907, p. 283. * W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1900, pp. 407-410; also N. V. Ussing, idem, vol. 26, 1896, p. 104. 3 Brogger, op. cit., pp. 418-422. 4 Am. Jour. Sci., 4th ser., vol. 26, 1909, p. 187. 6 See A. Damour, Bull. Soc. min., vol. 2, 1879, p. 15; and L. Brugnatelli, Zeitschr. Kryst. Min., vol.39, 1904, p. 209. 390 THE DATA OF GEOCHEMISTRY. The members of the olivine group are easily prepared by artificial means, and are of common occurrence in slags . 1 The first intentional synthesis of olivine was effected by Berthier , 2 by simply fusing its constituent oxides together. Fouque and Levy 3 also obtained it by fusing silica and magnesia with ferrous ammo- nium sulphate. In their synthesis of basalt 4 they observed olivine among the earliest crystallizations from the magma. J. J. Ebelmen 5 prepared forsterite by fusing a mixture of boric oxide, silica, and magnesia. In this case the boric oxide simply serves as a solvent of relatively low melting point, from which the synthetic mineral crys- tallizes just as ordinary salts crystallize from solution in water. A. Daubree 6 obtained olivine by recrystallization from fused meteorites, magnesian eruptive rocks, and serpentine. He also 7 prepared mix- tures of olivine and metallic iron, resembling certain meteorites, by partial oxidation of an iron silicide and subsequent fusion of the product. G. Lechartier 8 fused silica and magnesia with calcium chloride, and P. Hautef euille 9 operated with the same oxides and magnesium chloride. Olivine was produced in both cases when the oxides were in the proper proportions. By varying the proportions enstatite or enstatite and olivine together were formed. S. Meunier , 10 by heating magnesium vapor to redness in a mixture of water vapor and silicon chloride, obtained both olivine and enstatite. Fayalite was prepared by A. Gorgeu , 11 who heated ferrous chloride with silica to redness in a stream of moist hydrogen. Olivine is also formed, ac- cording to C. Doelter , 12 when hornblende is fused with calcium and magnesium chlorides, and is among the products of fusion of biotite, vesuvianite, tourmaline, clinochlore, and some garnets. Forsterite was obtained by E. T. Allen, F. E. Wright, and J. K. Clement 13 incidentally to their preparation of magnesian pyroxenes. Olivine is an essential pyrogenic constituent of many eruptive rocks, such as peridotite, norite, basalt, diabase, and gabbro. Dunite is a rock consisting of olivine alone, or at most accompanied by 1 See Fouqu6 and L6vy, Synthase des min^raux et des roches, p. 96; L. Bourgeois, Reproduction artificielle des min6raux, pp. 108-110; Vogt, Mineralbildung in Schmelzmassen, p. 8. A. Stelzner and H. Schulze (Neues Jahrb., 1882, pt. 1, p. 170) have described a slag containing a zinc-bearing fayalite; and H. Laspeyres (Zeitschr. Kryst. Min., vol. 7, 1883, p. 494) has reported another furnace product having the composition MnFe3Si20s. 2 Cited by Fouqu4 and L6vy, op. cit., p. 97. 2 Bull. Soc. min., vol. 4, 1881, p. 279. * Compt. Rend., vol. 92, 1881, p. 367. 5 Annales chim. phys., 3d ser., vol. 33, 1851, p. 56. 6 Compt. Rend., vol. 62, 1866, pp. 200, 369, 660. 7 Etudes synthfitiques de gSologie exp<5rimentale, p. 524. 8 Compt. Rend., vol. 67, 1868, p. 41. 9 Annales chim. phys., 4th ser., vol. 4, 1865, p. 129. 10 Compt. Rend., vol. 93, 1881, p .737. 11 Idem, vol. 98, 1884, p. 920. i* Min. pet. Mitt., vol. 10, 1888, p. 67; and Neues Jahrb., 1897, Band 1, p. 1. is Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 385. See also N. L. Bowen and O. Andorsen, Am. Jour. 6ci., 4th ser., vol. 37, p. 487, 1914. ROCK-FORMING MINERALS. 391 trivial amounts of accessories. Since olivine, fused with silica, yields enstatite, it can occur normally only in rocks low in silica. As the latter increases in amount, pyroxenes take its place. Olivine, how- ever, sometimes appears abnormally, as a minor accessory, in highly siliceous rocks like trachyte and andesite. Fayalite, for instance, was found by J. P. Iddings, 1 associated with tridymite in lithophyses of rhyolite and obsidian, in the Yellowstone Park. A similar occur- rence in the Lipari Islands is reported by Iddings and S. L. Pen- field. 2 At Rockport, Massachusetts, fayalite has been found in granite. 3 Olivine is also a common constituent of meteorites and is often conspicuously associated with metallic iron. As products of thermal metamorphism olivine and forsterite are found in limestones and dolomites, frequently accompanied by spinel. 4 The boltonite of Bolton, Massachusetts, is an occurrence of this kind. The members of the olivine group all undergo alteration with extreme facility. The typical alteration of peridotite rocks is into serpentine. By further changes, magnetite, magnesite, hvdromag- nesite, brucite, calcite, opal, and quartz may be formed. By oxidation of the iron silicate, limonite is produced. P. von Jeremeef 5 has described pseudomorphs of talc, serpentine, and epidote after olivine. The olivine was first transformed to serpentine, that into epidote, and that finally into talc and clay. Pseudomorphs of hornblende after olivine are recorded by F. Becke 6 and B. Kolenko. 7 By a reaction between olivine and feldspar, according to R. Brauns, 8 a pyroxene can be formed. Monticellite alters into serpentine and pyroxene; and C. H. Warren 9 found a ferrous anthophyllite, FeSiO s , derived from the fayalite of Rockport. THE MICAS. Muscovite . — Mono clinic. Composition normally Al 3 KH 2 Si 3 0 12 . Molecular weight, 399.6. Specific gravity, 2.85. Molecular volume, 140. Colorless when pure, but usually tinted slightly by impurities. Hardness, 2 to 2.5. Some varieties of muscovite differ from the normal compound in containing a higher proportion of silica. These all represent admix- tures of the isomorphous trisilicate Al 3 KH 2 Si 9 0 2 4 . Fuchsite is a muscovite containing small amounts of chromium, replacing alumi- num. Baddeckite 10 appears to be a muscovite containing much ferric 1 Am. Jour. Sci., 3d ser., vol. 30, 1885, p. 58. 2 Idem, vol. 40, 1890, p. 75. 3 See S. L. Penfield and E. H. Forbes, Am. Jour. Sci., 4th ser., vol. 1, 1896, p. 129- 4 See C. T. Clough and W. Pollard, Quart. Jour. Geol. Soc. vol. 55, 1899, p. 372 8 Zeitschr. Kryst. Min., vol. 32, 1900, p. 430. ® Min. pet. Mitt., vol. 4, 1882, p. 450. 7 Neues Jahrb., 1885, Band 2, p. 90. 8 Idem, 1898, Band 2, p. 79. 9 Am. Jour. Sci., 4th ser., vol. 16, 1903, p. 337. 10 G. C. Hoffmann, Ann. Rept. Geol. Survey Canada, vol. 9, 1896, p. 11 R. 392 THE DATA OF GEOCHEMISTRY. iron, due to admixtures of the compound Fe 3 KH 2 Si 3 0 12 . F. W. Clarke and N. H. Darton 1 have described an altered mica which seems to be derived in part from the same ferric salt. Roscoelite is similar, but with nearly two-thirds of the aluminum replaced by vanadium. 2 Sericite, margarodite, damourite, gilbertite, etc., are muscovites of secondary origin. P aragonite. — Monoclinic. A sodium mica, Al 3 NaH 2 Si 3 0 12 , corre- sponding to muscovite. Molecular weight, 383.5. Specific gravity, 2.9. Molecular volume, 132.2. Color, like muscovite. Hardness, 2.5 to 3. Lepidolite. — Monoclinic. A lithia-bearing mica of variable com- position. In most cases a mixture of a fluoriferous trisilicate, AlF 2 .Si 3 0 8 .R/ 3 , in which R'= (Li,K), with molecules of the muscovite type. Color commonly rose-red or lilac, but also white, gray, or brown. Specific gravity, 2.8 to 2.9. Cookeite, 3 Al 3 LiH (Si0 4 ) 2 (0H) 3 .H 2 0, is probably a derivative, by hydration, of lepidolite; but it may be an alteration of tourmaline. Polylithionite is another lithia mica in which the ratio Si:0 is entirely trisilicate. The separate exist- ence of such a compound among the micas sheds much light upon their constitution; but of that, more later. Zinnwaldite and cryo- phyllite are other lithia micas containing iron and intermediate in composition between lepidolite and the ferruginous biotites. Lepido- lite is found chiefly, if not exclusively, in albitic pegmatite veins and has little significance as a rock-forming mineral. Biotite. — Monoclinic. Normal composition, Al 2 Mg 2 KHSi 3 0 12 , but with admixtures of the corresponding ferric and ferrous salts in variable proportions. Molecular weight of the normal biotite, 420.3. Specific gravity, 2.7. Molecular volume, 155.6. The specific gravity of the iron biotites may reach 3.1. That is the density of siderophyl- lite, which is very near to the normal ferrous biotite in composition and has a molecular volume of 155.9. There are also biotites con- taining small amounts of chromium, barium, manganese, etc. Color, in biotite generally, green to black, rarely white, sometimes yellow to brown. Hardness, 2.5 to 3. Phlogopite. — Monoclinic. Composition variable; typical phlogo- pite approximates to AIMg 3 KH 2 Si 3 0 12 . Usually contains a low pro- portion of water and some fluorine; also iron in small quantities. Normal molecular weight, 418.6. Specific gravity, 2.75. Molecular volume, 152.2. Color, brown, yellowish, reddish, greenish, some- times white. Hardness, 2.5 to 3. Between phlogopite and biotite there are many intermediate mixtures; and the varieties contain- i Bull. U. S. Geol. Survey No. 167, 1900, p. 154. * F. W. Clarke, idem, p. 73. 3 See Clarke, Bull. U. S. Geol. Survey No. 588, 1914, p. 57. BOCK-FORMING MINERALS. 393 ing much ferric iron are known as lepidomelane. The ratios of the latter are commonly near those of biotite. CJiloritoid. — Monoclinic. 1 Composition, Al 2 Fe"H 2 Si0 7 ; being a very basic orthosilicate. Some magnesia or manganese may replace a part of the iron. Molecular weight, 252.5. Specific gravity, 3.45. Molecular volume, 73.2. Color, gray, greenish gray, and grayish or greenish black. Hardness, 6.5. Ottrelite, which is an important constituent of some schists, is probably the trisilicate corresponding to chloritoid, ALjFeHjSigOn. These minerals, together with mar- garite, seybertite, and xanthophyllite, form the clintonite group, or so-called brittle micas. They are all foliated, micaceous minerals, extremely basic, and free from alkalies. The true ferromagnesian micas often contain admixtures of these basic molecules. Although muscovite is very simple in its constitution, the other micas, including the clintonite series, are quite complex. Just as in the pyroxene and amphibole groups, we have to deal with isomorphous mixtures of different salts, which vary not only to some extent in type, but also in their “ replacements” of aluminum by iron or chromium, potassium and hydrogen by sodium or lithium, and magnesium by iron or manganese. In some of the brittle micas calcium also appears, and in lepidolite and phlogopite the equivalency of hydroxyl and fluorine has to be taken into account. Furthermore, the ferromag- nesian micas are highly alterable by hydration; and it is not always possible to be certain whether a change of that order may not have begun. In spite of all difficulties, however, the normal micas can be expressed by a smaller number of generalized formulae, which are all derivable from one general type, as follows : Muscovite, R /// 3 R / 3(Si0 4 )3 and R /// 3R / 3 (Si 3 0 8 ) 3 . Biotite, R /// 2 R // 2 R / 2 (Si0 4 ) 3 and R /// 2 R // 2 R / 2 (Si 3 0 8 ) 3 . Phlogopite, R /// 1 R // 3 R / 3 (Si0 4 ) 3 and R /// 1 R // 3 R / 3 (Si 3 0 8 ) 3 . According to J. Uhlig, 2 the rare mineral kryptotile, an alteration product of prismatine, is an end member of the muscovite series, with formula Al 3 H 3 (Si0 4 ) 3 . Possibly the claylike mineral leverrierite may be akin to kryptotile. To these normal micas must be added two basic types, E, / "F 2 .Si 3 0 8 K, , 3 in lepidolite, zinnwaldite, and some phlogopites, and the clintonite molecule R" , 0 2 K".Si 3 0 8 .R , 3, with its orthosilicate equivalent R ,/, 0 2 R*>Si0 4 .R , 3 . To each of these forms a known mica corresponds, so that the expressions involve no assumptions of hypothetical molecules. In G. Tschermak’s theory of the mica group, 3 hypothetical compounds are invoked with which no actual micas agree. 1 Triclinic according to H. F. Keller and A. C. Lane, Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 499. 2 Zeitschr. Kryst. Min., vol. 47, 1910, p. 215. See also A. Sauer, Zeitschr. Deutsch. geol. Gesell., vol. 38, 1886, p. 705. 3 Zeitschr. Kryst. Min., vol. 2, 1878, p. 14; vol. 3, 1879, p. 122. 394 THE DATA OF GEOCHEMISTRY. Several syntheses of mica have been reported, but they are not alto- gether satisfactory, for the reason that the products obtained were not, except in one instance, verified by analysis. Unfortunately, a large proportion of the work so far done in synthetic mineralogy has been purely qualitative, and therefore incomplete. A substance may be micaceous and yet a different thing from any natural member of the mica group. The true micas, as a rule, are hydrous minerals; water is one of their essential constituents; syntheses by igneous methods, at ordinary pressures, are therefore to be regarded with sus- picion. Some phlogopites are nearly anhydrous, however, and it would be unwise to condemn the reported syntheses without further investigation. The magnesian mica, described and partly analyzed by Jo H. L. Vogt, * 1 from the slags of the Kafveltorp copper works in Sweden, may have been a phlogopite of the type just indicated, with its hydroxyl replaced by some other monad radicle. To Fouque and Levy’s 2 synthesis of a mica trachyte, the objections just cited do not apply. They heated a powdered granitic glass with a little water, under pressure, and for a long time, to redness, and obtained an arti- ficial rock in which scales of mica were visible. In this synthesis water played a distinct part. By the prolonged heating of andalusite with a solution of potassium carbonate and potassium fluoride at 250°, C. Doelter 3 obtained scales of white mica. This transformation is instructive, for andalusite alters into muscovite quite readily. P. Hautefeuille and L. P. de Saint-Gilles 4 fused the constituents of an iron mica with potassium silicofluoride and found crystals resembling mica in their product. K. ChrustschofFs 5 work was more definite. He fused a mixture equivalent to a mica basalt with the fluorides of sodium, aluminum^ and magnesium, and also with potassium silicofluoride. After very slow cooling, the mass contained a micaceous mineral, which was separated and analyzed. It was essentially an anhydrous biotite. J. Morozewicz 6 added about 1 per cent of tungstic acid to a mixture having the composition of rhyolite, and obtained, after prolonged fusion and slow cooling, tables of biotite. C. Doelter, 7 in a series of memoirs, reports the formation of micas by the fusion of various natural silicates with fluorides. Hornblende, augite, pyrope, almandite, and grossularite, fused with sodium fluor- ide and magnesium fluoride, yielded, among other products, biotite. It must, however, have been a sodium biotite, for the materials used seem to have contained no potassium. Glaucophane treated in the 1 Berg- u. Hiittenm. Zeitung, vol. 47, p. 197. a Compt. Rend., vol. 113, 1891, p. 283. 1 Allgemeine chemische Mineralogie, p. 207. * Compt. Rend., vol. 104, 1887, p. 508. * Min. pet. Mitt., vol. 9, 1887, p. 55. « Neues Jahrb., 1893, Band 2, p. 48. 1 1dem, 1888, Band 2, p. 178; 1897, Band 1, p. 1. Also Min. pet. Mitt., vol. 10, 1888, p. 67. ROCK-FORMING MINERALS. 395 same way gave a phlogopite. Leucite, with sodium or potassium fluoride, was converted into an alkali mica and with magnesium fluoride yielded biotite. Andalusite, heated to redness with potas- sium silicofluoride and aluminum fluoride, gave muscovite, and when lithium carbonate was added to the mixture a lithia mica was obtained. An artificial mixture corresponding to KAlSi0 4 + Mg 2 Si0 4 , fused with sodium and magnesium fluoride, also formed biotite. From other mixtures he produced muscovite, phlogopite, and an iron mica. None of these products seems to have been analyzed, and as their generation is ascribed to presumably anhydrous materials, it is probable that they were analogous to rather than identical with the natural micas. Possibly they were micas containing fluorine in place of hydroxyl. In nearly all the reported syntheses of mica fluorides have played an important part, but their exact function is unknown. Primary muscovite is essentially a mineral of the deep-seated rocks, especially of the granites and quartz porphyries. It is never found in recent eruptives. From its water content we may infer that it was formed under pressure. Muscovite is also abundant in mica schist, and paragonite is similarly found in a paragonite schist. As an alteration product of other minerals muscovite is very common. Feldspar, topaz, andalusite, kyanite, nephelite, spodumene, the scapo- lites, and various other silicates alter readily into mica. Pinite and several other pseudomorphous minerals of like character consist of muscovite more or less impure. Lepidolite is probably in many oases secondary after muscovite, for it often forms margins upon plates of the latter mineral. Cryophyflite forms similar margins upon lepi- domelane. Biotite is an important constituent of many massive igneous rocks, such as granite, syenite, diorite, trachyte, andesite, mica basalt, etc. It forms among the earliest secretions, immediately following the ores, apatite and zircon. It is sometimes altered by magmatic corro- sion to a mixture of augite and magnetite. 1 Pressure seems to con- dition its formation. Phlogopite occurs chiefly in granular Archean limestones and in serpentine ; but W. Cross 2 has described it as a constituent of a peculiar igneous rock, wyomingite. Chloritoid and ottrelite are found only in phyllitic schists, 3 and are of minor importance. Muscovite, under ordinary conditions, is one of the least alterable of minerals. The feldspar of a granite may be completely kaolin- ized, while the embedded plates of mica retain their brilliancy almost unchanged. By treatment with aqueous reagents at 500°, however, 1 For a discussion of this alteration, see H. S. Washington, Jour. Geology, vol. 4, 1896, p. 257. 2 Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 115. * See A. Cathrein, Min. pet. Mitt., vol. 8, 1887, p. 331; and L. van Werveke, Neues Jahrb., 1885, Band 1, p. 227. 396 THE DATA OF GEOCHEMISTRY. C. and G. Friedel 1 transformed muscovite into nephelite, sodalite, leucite, orthoclase, and anorthite. Upon fusion, according to C. Doelter, 2 muscovite breaks up into leucite glass, and a substance resembling nephelite. Lepidolite and zinnwaldite behave in a similar manner. W. Vernadsky 3 observed corundum and sillimanite among the fusion products of mica. From the composition of muscovite a splitting up into water, leucite, and sillimanite may be inferred, according to the equation — Al 3 KH 2 Si 3 0 12 =AlKSi 2 0 6 + Al 2 Si0 5 + H 2 0 ; and with this the reported derivation of muscovite from leucite can be correlated. 4 Biotite, according to Doelter, yields no leucite upon fusion, but breaks up into olivine and spinel, with other less com- pletely identified substances. On the other hand, H. Backstrom 5 fused biotite and found olivine, leucite, a little spinel, and glass to be the substances formed by its decomposition. Unlike muscovite, biotite and phlogopite alter easily, and pass into a series of apparently indefinite substances known as “vermiculites.” The change, however, is very simple, and consists merely in the replacement of the alkaline metals by hydrogen, with assumption of additional, loosely combined water. From the typical ferromag- nesian micas the following derivatives are thus formed: From Al 2 Mg 2 KHSi 3 0 12 Al 2 Mg 2 H 2 Si 3 0 12 .3H 2 0 . From AlMg 2 KH 2 Si 3 0 12 AlMg 3 H 3 Si 3 0 12 .3H 2 0 . From any mixture of biotite and phlogopite molecules the cor- responding hydrated mixture may be generated. These compounds, so simply related to the parent substances, form a series intermediate between the micas and the chlorites and mark a transition into the latter group of minerals, which will be considered next in order. 6 THE CHLORITES. Under this general name a considerable number of minerals are embraced which are closely related to the micas. They are, how- ever, much more basic, highly hydrated, and free from alkalies. They are silicates of aluminum or ferric iron, with magnesium or ferrous iron, and resemble the micas crystallographically as well as in the scaly or foliated habit which they commonly assume. The fol- 1 Compt. Rend., vol. 110, 1890, p. 1170. 2 Neues Jahrb., 1897, Band 1, p. 1. 3 Cited by Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 26. 4 See Doelter’s experiment, cited above. 6 Geol. Foren. Forhandl., vol. 18, 1896, p. 162. 6 On the alteration products of the magnesian micas, see E. Zschimmer, Jenaische Zeitschr., vol. 32, 1898, p. 551. On the action of water upon micas, A. Johnstone, Quart. Jour. Geol. Soc., vol. 45, 1889, p. 363. For analyses of vermiculites, see E. S. Dana, System of mineralogy, 6th ed., pp. 664-668; also F. W. Clarke and E. A. Schneider, Bull. U. S. Geol. Survey No. 78, 1891; Bull. No. 90, 1892. The earlier papers of J. P. Cooke and F. A. Genth are also important. ROCK-FORMING MINERALS. 397 lowing species are recognized by Dana, 1 who assigns to them the annexed empirical formulae : Clinochlore 1 Penninite }H 8 (Mg,Fe) 5 Al 2 Si 3 0 18 . Prochlorite II« l (Fe,Mg). ! 3 Al 14 Si 1 30 110 . Corundophilite H 2 o(Fe,Mg) 11 Al 8 Si 6 0 45 . Daphnite H 56 F 627 -^-l 2 9 Sii 8 0 42 i • Cronstedtite H 6 (Fe J Mg) 3 Fe /// 2 Si 2 0 1 3 . Thuringite H 18 Fe 8 (Al,Fe) 8 Si 6 0 41 . Stilpnomelane Strigovite H 4 (Fe,Mn) 2 (Fe, Al) 2 Si 2 O n . Diabantite H^Mg^FehaAfiSigO^. Aphrosiderite H 10 (Fe,Mg) 6 Al 4 Si 4 O 25 . Delessite II 10 (Mg, Fe) 4 Al 4 Si 4 0 22 . Rumpfite H 28 Mg 7 Al 16 Si 10 O 65 . To these may be added the more or less uncertain minerals amesite, metachlorite, klementite, chamosite, epichlorite, etc. None of the formulae given above is fixed and definite, for each of the many “chlorites” is variable in composition. The minerals, like the ferromagnesian micas, are mixtures of compounds, and several attempts to disentangle their components have been made. 2 The simplest and most natural interpretation of the chlorites represents them as formed from a series of compounds parallel with those iden- tified in the micas and vermiculites, according to the following scheme: Normal micas. Al 3 KH 2 (Sid 4 ) 3 . Al 2 Mg 2 KH(Si0 4 ) 3 . AlMg 3 KH 2 (Si0 4 ) 3 . A10 2 Mg.Si0 4 .R / 3 . Vermiculites. Al 2 Mg 2 H 2 (Si0 4 ) 3 .3H 2 0. AlMg 3 H 3 (Si0 4 ) 3 . 3H 2 0 . A10 2 Mg. SiC^R^ .3H 2 0 . Normal chlorites. Al 2 (Mg0H) 4 H 2 (S10 4 ) 3 . Al(Mg0H) 6 H 3 (Si0 4 ) 3 . A10 2 Mg.Si0 4 .R / 3 . On this basis the relations between the several series are clear and in accord with the natural occurrences of the minerals. In penninite and clinochlore we have varying mixtures of the first and second chloritic types, just as among the micas we find examples interme- diate between biotite and phlogopite. Prochlorite appears to be a derivative of the last molecule, having the formula — A10 2 R'.Si0 4 o (R"OH)H 2 , in which R" is partly Fe and partly Mg. 3 It is obvious, from their hydrous character, that the chlorites can not form as pyrogenic minerals. They are always of secondary origin; and when they appear in volcanic rocks it is as the result of 1 System of mineralogy, 6th ed., p. 643. 2 See G. Tschermak, Sitzungsb. K. Akad. Wiss. Wien, vol. 99, Abth. 1, 1890, p. 174; vol. 100, Ajth. 1, p. 29. R. Brauns, Neues Jahrb.,Band l,1894,p. 205, and Chemische Mineralogie,p. 221. F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914, pp. 59-65. An earlier discussion by Clarke, on different lines, is given in Bull. U. S. Geol. Survey No. 113, 1893, p. 11. 8 For the other chloritic minerals see F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914, pp. 59-65. 398 THE DATA OF GEOCHEMISTRY. hydrothermal alteration. Almost any aluminous ferromagnesian mineral may yield a chlorite in this way. Augite, hornblende, bio- tite, vesuvianite, epidote, tourmaline, or garnet may be the parent mineral. 1 Chlorites have been produced artificially by G. Friedel and F. Grandjean, 2 by the action of alkaline solutions on pyroxenes. When a magnesian chlorite, such as clinochlore, is strongly ignited, it breaks down into a soluble and an insoluble portion, and the latter has the composition of spinel. 3 This fact is strong evidence against Tschermak’s theory of the chlorite group, in which the normal series is regarded as formed by mixtures of serpentine, H 4 Mg 3 Si 2 0 9 , with amesite, H 4 Mg 2 Al 2 Si0 9 . For serpentine, on ignition, splits up into water, olivine, and enstatite, and the last-named mineral does not appear among the decomposition products of clinochlore. The latter, therefore, contains no serpentine, and the theory which assumes its presence falls to the ground. C. Doelter 4 reports spinel, olivine, and augite as formed by the fusion of clinochlore; but the experi- ments conducted in the laboratory of this Survey exclude the insolu- ble augite from the list of probabilities. Chlorites are abundant among the metamorphic schists, chlorite schist being the commonest occurrence. An interesting metamorpho- sis of such a rock, a phyllite containing approximately 75 per cent of muscovite with 25 of chlorite, is reported by K. Dalmer. 5 With almost no change of composition, other than loss of water, it was transformed into a mixture of andalusite and biotite. THE MELILITE GROUP. Melitite. — Tetragonal. A silicate of aluminum and calcium of variable composition, with Fe'" replacing some Al, and Mg or Na replacing a part of the Ca. Specific gravity, 2.9 to 3.1. Hardness, 5. Color, white, yellow, greenish yellow, brown. Gehlenite . — Tetragonal. Composition variable, as with melilite. The formula commonly assigned to gehlenite, Al 2 Ca 3 Si 2 O 10 , is not sustained by the best evidence. Specific gravity, 3. Hardness, 5.5 to 6. Color, grayish green to brown. Akermanite. — Tetragonal. Composition, Ca 4 Si 3 O 10 , with about one- third of the calcium replaced by magnesium. According to A. L. Day and E. S. Shepherd 6 a calcium silicate of this formula can not be deposited from lime-silica fusions. The magnesia is essential to its formation. Ordinarily found only in slags, but the natural min- 1 For a complete discussion of pseud omorphous chlorite after pyrope, see J. Lemberg, Zeitschr. Deutsch. geol. Gesell., vol. 27, 1875, p. 531. 2 Bull. Soc. min., vol. 32, 1909, p. 150. 8 F. W. Clarke and E. A. Schneider, Bull. U. S. Geol. Survey No. 113, 1893, pp. 27-33. * Neues Jahrb., 1897, Band 1, p. 1. 6 Idem, 1897, Band 2, p. 156. 8 Am. Jour. Sci., 4th ser., vol. 22, 1906, p. 265. ROCK-FORMING MINERALS. 399 eral is reported by F. Zambonini 1 as occurring in calcareous blocks at Monte Somma. These three isomorphous silicates are closely related to one another. J. H. L. Vogt 2 regards gehlenite and akermanite as the two inde- pendent species, which, isomorphously commingled, form the vari- able melilite. This view is plausible, but not universally accepted. Furthermore, although melilite is a pyrogenic mineral characteristic of certain eruptive rocks, natural gehlenite has been found only as a product of contact metamorphism in limestones. If gehlenite were a constituent of melilite, we should expect to find igneous rocks in which it appeared as an essential component, or at least as a con- spicuous accessory. A more probable interpretation of melilite and gehlenite treats them as intermediate mixtures of silicates analogous to the plagioclase feldspars. One of these silicates, Al 2 Ca 2 Si0 7 , has been prepared synthetically by E. S. Shepherd and G. A. Rankin in the Geophysical Laboratory of the Carnegie Institution. It is easily formed by direct fusion of a mixture of its component oxides. The other silicate, Al 2 Ca9(Si0 4 ) 6 is not known by itself, but is approxi- mated by some artificial gehlenites. It is nearly related in structure to minerals of the garnet and scapolite groups. 3 Both melilite and gehlenite are common minerals hi slags, 4 and both have been prepared synthetically. An artificial melilite basalt was prepared by J. Morozewicz, 5 and the mineral was also found by Fouque and Levy 6 among the constituents of some of their synthetic rocks. In Morozewicz ’s preparation the melilite was accompanied by augite, plagioclase, olivine, corundum, and spinel. Melilite and feldspar were the last silicates to crystallize from the magma. F. Fouque 7 has shown that melilite is formed when an augite andesite or a basalt is fused with lime, and he gives analyses of two products thus obtained. G. Bodlander 8 found melilite in a sample of Portland cement; but according to Vogt 9 the mineral was not pure. L. Bour- geois 10 prepared melilite by direct fusion of silica, lime, alumina, and certain other oxides commingled in proper proportions, but could not obtain the calcium alumosilicate alone. The presence of iron, 1 Mineralogia Vesuviana, p. 255. * MineralbMung in Schmelzmassen, 1892, pp. 96-176. See also G. Bodlander, Neues Jahrb., Band 1, 1893, p. 15; and F. Fouqu6, Bull. Soc. min., vol. 23, 1900, p. 10. Also a more recent discussion by Vogt, Die Sflikatschmelzlosungen, pt. 1, 1903, p. 49. F. Zambonini (Zeitschr. Kryst. Min., vol. 41, 1906, p. 226) has advanced strong arguments against Vogt’s hypothesis. 3 See F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914, pp. 31-34. * See L. Bourgeois, Reproduction artificielie des mineraux, p. 123. J. H. L. Vogt, Mineralbildung in Schmelzmassen, 1892. F. Fouque, Bull. Soc. min., vol. 9, 1886, p. 287. P. Heberdey, Zeitschr. Kryst. Min., vol. 26, 1896, p. 19. J. S. Biller, Am. Jour. Sci., 3d ser., vol. 37, 1889, p. 220. 5 Min. pet. Mitt., vol. 18, 1898, p. 191. 6 Bull. Soc. min., vol. 2, 1879, p. 105. 7 Idem, vol. 23, 1900, p. 10. 8 Neues Jahrb., Band 1, 1892, p. 53. 8 Idem, Band 2, 1892, p. 73. * Annales chim. phys., 5th ser., vol. 29, 1883, p. 450. 400 THE DATA OF GEOCHEMISTRY. magnesia, or manganese was essential to a successful synthesis. Soda also is probably essential; at all events, melilite forms more readily when soda is present. All natural melilite contains soda. C. Doelter and E. Hussak 1 found melilite among the fusion products of garnet and vesuvianite, and Doelter 2 reports it also as formed when tourma- line is fused with calcium chloride and sodium fluoride. The synthesis of gehlenite was effected by L. Bourgeois, 3 who simply fused the con- stituent oxides together in the proportions indicated by the formula of the species. Melilite is a mineral found only in the younger eruptives; never in the plu tonic rocks or crystalline schists. It is frequently associated with nephelite or leucite, and sometimes takes the place of feldspar. Perofskite is one of its most constant companions. Its origin is always pyrogenic. 4 Its most remarkable occurrence is in the Uncom- pahgre quadrangle, Colorado, where it forms about two-thirds of a rock which contains also pyroxene, magnetite, perofskite, and apatite, with other minor accessories. The melilite is enormously developed, and cleavages a foot across are not rare. 5 Alterations of melilite seem to have been little studied. A. Cath- rein 6 has described pseudomorphs of pyroxene (fassaite) and gros- sularite after gehlenite. By heating gehlenite with a solution of potassium carbonate to 200°, J. Lemberg 7 obtained calcium carbonate and an amorphous product having the composition of a potassium mica. A fibrous, zeolitic alteration of the Uncompahgre melilite, cevollite, has been described by E. S. Larsen and W. T. Schaller. 8 THE GARNETS. Grossularite. — Isometric. Composition, Ca 3 Al 2 Si 3 0 12 . Molecular weight, 451.7. Specific gravity, 3.5. Molecular volufne, 129. Color, white, yellow, brown, and sometimes pale green or rose-red. The col- oration is due to impurities. Pyrope. — Isometric. Composition, Mg 3 Al 2 Si 3 0 12 . Molecular weight, 404.6. Specific gravity, 3.7. Molecular volume, 109.4. Color, deep red to nearly black. Almandite. — Isometric. Composition, Fe 3 Al 2 Si 3 0 12 . Molecular weight, 499.1. Specific gravity, 3.9 to 4.2. Molecular volume, 118. Color, red to brown and black. Pyrope and almandite shade one into 1 Neues Jahrb., 1884, Band 1, p. 159. 2 Idem, 1897, Band l,p.l. 8 Annales chim. phys., 5th ser., vol. 29, 1883, p. 448. 4 For data upon melilite rocks see A. E. Tomebohm, Geol. Foren. Forhandb, vol. 6, 1882, p. 240. A. Stelzner, Neues Jahrb., Beil. Band 2, 1883, p. 369. F. D. Adams, Am. Join:. Sci., 3d ser., vol. 43, 1892, p. 269. C. H. Smyth, idem, vol. 46, 1893, p. 104. The last two references deal with American occurrences. 5 See E. S. Larsen and J. F. Hunter, Jour. Washington Acad. Sci, voL 4, 1914, p. 473. 6 Min. pet. Mitt., vol. 8, 1887, p. 400. 7 Zeitschr. Deutsch. geol. Gesell., vol. 44, 1892, p. 237. 8 Jour. Washington Acad. Sci., vol. 4, 1914, p. 480. ROCK-FORMING MINERALS. 401 the other through varying mixtures of the iron and magnesium com- pounds. Spessartite. — Isometric. Composition, Mn 3 Al 2 Si 3 0 12 . Molecular weight, 496.4. Specific gravity, 4.2. Molecular volume, 118. Color, red to brown. Andradite, melanite, or common garnet. — Isometric. Composition, Ca 3 Fe"' 2 Si 3 0 12 . Molecular weight, 509.3. Specific gravity, 3.85. Molecular volume, 158.2. Color, green, yellow, brown, or black. Uvarovite. — Isometric. Composition, Ca 3 Cr 2 Si 3 0 12 . Molecular weight, 501.7. Specific gravity, 3.5. Molecular volume, 143. Color, emerald-green. The foregoing six species, with their many isomorphous mixtures, form the important garnet group. With them may be included the rare mineral schorlomite, which contains titanium partly replacing silicon and ferric iron. Its formula is Ca 3 (Fe,Ti /// ) 2 (SiTi iv ) 3 0 12 . 1 The sodium garnet lagoriolite, Na 6 Al 2 Si 3 0 12 , which was obtained by J. Morozewicz 2 from some of his artificial magmas, also belongs here. Its existence accounts for the small amounts of alkalies which appear in some analyses of grossularite, although they may be due in part to inclusions. Garnets are peculiarly prone to carry other species as inclosures within their crystals. Some garnets are hardly more than shells enveloping other species. 3 Although garnet is undoubtedly a pyrogenic mineral, its synthesis is attended by considerable difficulties. When fused by itself garnet breaks up into other compounds. C. Doelter and E. Hussak, 4 upon fusing garnets alone, obtained meionite, melilite, anorthite, lime olivine, a calcium nephelite (?), hematite, and spinel, the products varying with the composition of the original mineral. By fusing grossularite with sodium and magnesium fluorides, Doelter 5 obtained biotite, anorthite, meionite, olivine, and magnetite. L. Bourgeois, 6 from the fusion of a mixture equivalent to grossularite, obtained anorthite and monticellite; and J. H. L. Vogt 7 reports anorthite as formed under similar conditions. When magnesia, oxide of manga- nese, or iron oxide was added to Vogt’s mixture, melilite was also produced. The syntheses of garnet reported by several early inves- tigators 8 are of doubtful authenticity. 1 R. Soltmann (Zeitschr. Kryst. Min., vol. 18, 1891, p. 628) has described a melanite garnet containing 11.01 per cent of Ti 02 , which should probably be partly reduced to T^Os- 2 Min. pet. Mitt., vol. 18, 1898, p. 147. 3 For systematic papers on the garnet group see W. C-. Brogger and H. Backstrom, Zeitschr. Kryst. Min., vol. 18, 1891, p. 209; E. Weinschenk, idem, vol. 25, 1896, p. 365; H. E. Boeke, idem, vol. 53, 1913, p. 149; and J. Uhlig, Verhandl. Naturhist. Verein preuss. Rhcinlande u. Westfalens, vol. 67, 1911, p. 307. Uhlig gives many analyses. 4 Neues Jahrb., 1884, Band 1, p. 158. & Idem, 1897, Band 1, p. 1. 6 Annales chim. phys., 5th ser., vol. 29, 1883, p. 458. 2 Mineralbildung in Schmelzmassen, 1892, p. 187. 8 See Fouqu6 and Ldvy, Synthase des mineraux et des roches, p. 122. 97270°— Bull. 616—16 26 402 THE DATA OF GEOCHEMISTRY. Bourgeois, however, in the research just cited, prepared spessartite by fusing together its constituent oxides in the proper proportions. A. Gorgeu 1 also obtained spessartite when pipe clay was fused with an excess of manganese chloride. A similar fusion with calcium chloride gave, with other products, crystals which were possibly grossularite. Fouque and Levy 2 report melanite as formed when nephelite and pyroxene are fused together. L. Michel 3 produced melanite and sphene by heating a mixture of ilmenite, silica, and cal- cium sulphide to 1,200°. In this case the artificial melanite was ver- ified by analysis. E. S. Shepherd and G. A. Kankin 4 mention, but without details, the formation of grossularite by the action of alu- minum chloride upon calcium orthosilicate under pressure. Apparently pyrogenic garnet can be produced only during a limited range of temperatures, and the success of an attempted synthesis depends upon securing the exact conditions. Pressure, also, may exert some influence upon the process. 5 Garnet, especially andradite, is an exceedingly common mineral, and is found as an accessory in a great variety of rocks. Grossular- ite is found principally in crystalline limestones, where it has been developed by contact metamorphism. Almandite and andradite are common in granitic rocks, gneisses, etc. Andradite also occurs as an accessory mineral in subsilicio eruptives, especially in leuoite and nephelite rocks. It is also found in serpentines, in iron ore beds, and as a product of contact action, associated with wollastonite and pyroxene, in certain volcanic rocks. Pyrope is often found in perido- tites and the serpentines derived from them. Spessartite occurs in granite, quartzite, and some schists. W. Cross 6 has reported it from lithophyses in rhyolite. Garnets are also abundant in many crystal- fine schists, such as garnet rock, garnet amphibolite, garnet hornfels, garnet-mica schist, etc. Eclogite is a rock in which garnet and a green pyroxene are the principal minerals. Alterations of garnet are exceedingly common. A. Cathrein, 7 describing the rocks of a single region, reports pseudomorphs after garnet of scapofite, epidote, ofigoclase, hornblende, saussurite, and chlorite. Chloritic pseudomorphs are perhaps the most frequent. 8 The pyrope found in peridotite rocks is often surrounded by a zone or shell of altered material, to which A. Schrauf 9 has given the 1 Annales chim. phys., 6th ser., vol. 4, 1885, pp. 536, 553. 2 Compt. Bend., vol. 87, 1878, p. 962. 3 Idem, vol. 115, 1892, p. 830. * Am. Jour. Sci., 4th ser., vol. 28, 1909, p. 305. 6 See L. L. Fermor (Rec. Geol. Survey India, vol. 43, pt. 1, 1913, p. 41, and Jour. Asiatic Soc. Bengal, vol. 8, 1912, p. 315) on the probable formation of garnet at great depths. e Am. Jour. Sci., 3d ser., vol. 31, 1886, p. 432. 7 Zeitschr. Kryst. Min., vol. 10, 1885, p. 433. 8 See for example J. Lemberg, Zeitschr. Deutsch. geol. Gesell., vol. 27, 1875, p. 531, and S. L. Penfield and F. L. Sperry, Am. Jour. Sci., 3d ser., vol. 32, 1886, p. 307. 9 Zeitschr. Kryst. Min., vol. 6, 1882, p. 358. BOCK-FORMING MINERALS. 403 name kelyphite. It is, however, not a substance of uniform com- position. The kelyphite studied by A. von Lasaulx 1 was mainly a mixture of pyroxenes and amphiboles. J. Mrha 2 described a kelyphite consisting of bronzite, monoclinic pyroxene, picotite, and hornblende. The pyrope from the peridotite dikes of Elliott County, Kentucky, described by J. S. Diller, 3 was surrounded by a similar shell made up of biotite and magnetite, with a little pico- tite. Biotite is not an uncommon derivative of the magnesian gar- nets. Garnet itself appears occasionally as an alteration product of other minerals. P. Jeremeef 4 has recorded pseudomorphs of grossularite after vesuvianite; and grossularite after gehlenite was observed by A. Cathrein. 5 VESUVIANITE. Tetragonal. Composition variable, and best represented by the general formula Al 2 Ca 7 Si 6 0 24 B/ 4 ; in which K' 4 may be Ca 2 , (A10H) 2 , (A10 2 H) 4 , or H 4 . Some replacements of magnesium and iron are usually present; a little fluorine may be substituted for hydroxyl, and in the variety wiluite there is a small amount of boric oxide. 6 Specific gravity, 3.35 to 3.45. Hardness, 6.5. Color, brown or green, some- times yellow or pale blue. A massive variety of vesuvianite resem- bling jade has been called calif ornite. Vesuvianite has not yet been prepared synthetically. It is known chiefly as a product of contact metamorphism in limestones, asso- ciated with pyroxene, scapolite, garnet, wollastonite, and epidote. It is also found in some serpentines, chlorite schist, gneiss, etc. Pseudomorphs of grossularite after vesuvianite have been reported by P. Jeremeef. 7 When vesuvianite is fused, it breaks up into meionite, melilite, anorthite, and possibly a lime olivine. 8 THE SCAPOLITES. Meionite. — Tetragonal. Composition, Ca 4 Al 6 Si 6 0 25 . Molecular weight, 893.4. Specific gravity, 2.72. Molecular volume, 328.4. Colorless or white. Hardness, 5.5 to 6. Marialite. — Tetragonal. Composition, Na 4 Al 3 Si 9 0 24 Cl. Molecular weight, 848.4. Specific gravity, 2.57. Molecular volume, 330.1. Colorless or white. Hardness, 5.5 to 6. 1 Verhandl. Naturhist. Ver. preuss. Rheinlande u. Westfalens, vol. 39, pt. 2, 1882, p. 114. 2 Min. pet. Mitt., vol. 19, 1899, p. 111. 3 Bull. U. S. Geol. Survey No. 38, 1887. * Zeitschr. Kryst. Min., vol. 31, 1899, p. 505. 6 Min. pet. Mitt., vol. 8, 1887, p. 400. 6 See F. W. Clarke and G. Steiger, Bull. U. S. Geol. Survey No. 262, 1905. For other interpretations of vesuvianite see P. Jannasch and P. Weingarten, Zeitschr. anorg. Chemie, vol. 8, 1895, p. 356; M. Weibull, Zeitschr. Kryst. Min., vol. 25, 1895, p. 1; A. Kenngott, Neues Jahrb., Band 1, 1891, p. 200; H. Sjogren, Geol. Foren. Forhandl., vol. 17, 1895, p. 267. 7 Zeitschr. Kryst. Min., vol. 31, 1899, p. 505. 8 C, Doelter and E. Hussak, Neues Jahrb., 1884, Band 1, p. 158. 404 THE DATA OF GEOCHEMISTRY. These two species, with their isomorphous mixtures, form the scapolite group as interpreted by G. Tschermak. 1 Intermediate between them, and analogous to the plagioclase feldspars lying between anorthite and albite, are the following scapolites, which have received independent names: Wernerite MegM^ to Me^a^ Mizzonite or dipyre M^Maa to Me^ag The reported syntheses of scapolite are not altogether conclusive. L. Bourgeois 2 attempted to prepare meionite by fusing together its constituent oxides, and obtained principally anorthite. By adding fragments of marble to a molten basaltic glass, however, he observed in one case the formation of crystals which were probably meionite. By fusing a leucitite with the fluorides of sodium and calcium, K. B. Schmutz 3 obtained an artificial rock containing scapolite; and a similar experiment with eclogite also yielded the mineral. The same procedure with epidote and fluorides gave C. Doelter 4 a product in which meionite was recognized. Doelter also reports the synthesis of meionite by fusion of the mixed oxides, lime, silica, and alumina; and by fusion of a silicate, CaAl 2 Si 2 0 8 , with sodium chloride. His attempts to prepare marialite failed. E. S. Shepherd and G. A. Rankin 5 obtained meionite by heating a glass of that composition with a solution of sodium chloride in a bomb. They give no details, however. The scapolites occur principally in the crystalline schists, gneisses, amphibolites, and metamorphosed limestones. They are commonly products of metamorphic contact action and appear to be, as their composition would indicate, derived from plagioclase feldspar. They have been found as secondary minerals in various eruptive rocks. 6 In Norway scapolite rocks are associated with masses of apatite especially at Oedegaarden. In this instance J. W. Judd 7 has traced the development of the scapolite from plagioclase, and has ascribed the transformation partly to the action of sodium chloride solutions contained in cavities of the rock, and partly to powerful mechanical stresses. A. Lacroix, 8 however, regards the change as due to contact 1 Min. pet. Mitt., vol. 7, p. 400, 1886; Monatsh. Chemie, vol. 4, 1883, p. 851. Compare F. W. Clarke’s constitutional formulae in Bull. U. S. Geol. Survey No. 588, 1914, p. 36; and A. Himmelbauer, Sitzungsb. K. Akad. Wiss. Wien, 1910, Abth. 1, p. 119. A scapolite containing the sulphate radicle S0 4 has recently been described by R. Brauns, Neues Jahrb., Beil. Band 39, 1914, p. 121. It is named silvialite. Also scapolite containing carbonate groups by L. H. Borgstrom, Zeitschr. Kryst. Min., vol. 54, 1914, p. 238. 2 Annales chim. phys., 5th ser., vol. 29, 1883, pp. 446, 472. 3 Neues Jahrb., 1897, vol. 2, pp. 133, 149. * Idem, vol. 1, p. 1. 6 Am. Jour. Sci., 4th ser., vol. 28, p. 305, 1909. e See F. Zirkel, Lehrbuch der Petrographie, vol. 1, 1893, p. 382. W. Salomon, Min. pet. Mitt., vol. 15, 1895, p. 159, gives a good bibliography relative to dipyre. 7 Mineralog. Mag., vol. 8, 1889, p. 186. 8 Bull. Soc. min., vol. 14, 1891, p. 16. In vol. 12, 1889, p. 83, Lacroix has an elaborate monograph upon scapolite rocks. BOCK-FORMING MINERALS. 405 action between the rock and the apatite, although in other localities solutions of chlorides appear to be operative. Mechanical agencies are considered by Lacroix to be unimportant. At the Oedegaarden locality, which has been studied by several authorities, a granitic mixture of pyroxene and feldspar has been transformed into an aggregate of hornblende and scapolite. By fusion Fouque and Levy 1 transformed it back again into pyroxene and labradorite. A Canadian scapolite diorite has been described by F. D. Adams and A. C. Lawson, 2 and H. Lenk 3 has studied an augite-scapolite rock from Mexico. The scapolites are exceedingly alterable, and most so toward the sodium or marialite end of the series. Many of the alteration prod- ucts have been regarded as distinct species and have received inde- pendent names. Pseudomorphs of mica, often in the form of ‘ ‘ pinite,” after scapolite are very common. Alterations into epidote, steatite, kaolin, and free silica are also recorded. A. Cathrein 4 has reported pseudomorphs of scapolite after garnet. IOLITE. Iolite or cordierite. — Orthorhombic. F ormula, 5 II 2 (Mg,F e) 4 Al 8 Si 10 O 37 . Molecular weight and volume variable on account of variations be- tween Mg and Fe. Specific gravity, 2.60 to 2.66. Color, blue, often smoky or grayish. Hardness, 7 to 7.5. A possible synthesis of iolite was reported by L. Bourgeois, 6 who fused silica, magnesia, and alumina together in proper proportions. J. Morozewicz 7 also obtained it in his experiments upon artificial magmas, supersaturated with alumina, of the general formula R0.mAl 2 0 3 .7iSi0 2 . When magnesia and iron were present and n was greater than 6, iolite was formed. In short, he produced an arti- ficial cordierite-vitrophyrite, resembling the African rock described by G. A. F. Molengraaf. 8 These syntheses, however, were made with anhydrous materials; and the product could not have been identical with the iolite of natural occurrences. All the trustworthy analyses of the mineral show that water is one of its essential constituents. Iolite is found in nature in a great variety of rocks, including both metamorphic rocks and eruptives. It has been reported in granite, quartz porphyry, basalt, quartz trachyte, biotite dacite, and andesite; 1 Bull. Soc. min., vol. 2, 1879, p. 112. a Canadian Rec. Sci., vol. 3, 1888, p. 186. 8 Neues Jahrb., 1899, Band 1, ref. 73. 4 Zeitschr. Kryst. Min., vol. 9, 1884, p. 378; vol. 10, 1885, p. 434. 6 Formula based upon O. C. Farrington’s analysis, Am. Jour. Sci., 3d ser., vol. 43, 1892, p. 13. M. Weibull (Geol. Foren. Forhandl., vol. 22, 1900, p. 33) regards the mineral as anhydrous, and writes the formula Mg2Al 2 (A10) 2 Si50i6. c Annales chim. phys., 5th ser., vol. 29, 1883, p. 462. 7 Min. pet. Mitt., vol. 18, 1898, pp. 68, 167. See ante, p. 338, under “Corundum.” 8 Neues Jahrb., Band 1, 1894, p. 79. 406 THE DATA OF GEOCHEMISTEY. and seems to be a primary separation from the magmas. 1 In order of deposition it follows biotite, but precedes the feldspars. In cor- dierite gneiss and cordierite hornfels iolite is a characteristic con- stituent. The gneiss from Connecticut described by E. O. Hovey 2 consisted mainly of biotite, quartz, and iolite, with some plagioclase. Iolite is also well known as a product of contact metamorphism. For example, Bucking 3 found it in sandstones which had been vitrified by contact with basalt; and Kikuchi 4 has described a Japanese locality where iolite occurs in slate at contact with granite. Iolite alters with great ease, taking up water and alkalies. The product is usually an impure mica, and many pseudomorphs of this character have received distinctive names. Chlorophyllite, praseolite, aspasiolite, gigantolite, fahlunite, pinite, etc., are merely altered iolite. 5 THE ZOISITE GROUP. Zoisite. — Orthorhombic. 6 Composition, HCa 2 Al 3 Si 30 13 . Molecular weight, 455.9. Specific gravity, 3.25 to 3.37. Molecular volume, 138. Color, white, gray, greenish, yellowish, reddish. Hardness, 6 to 6.5. Epidote. — Monoclinic. Composition like zoisite, but with varying replacements of A1 by Fe. The variety with little or no iron has been called clinozoisite. Specific gravity, 3.25 to 3.5. Color, com- monly green, yellowish or brownish green, to black, sometimes red, yellow, or gray; rarely colorless. Hardness, 6 to 7. Piedmontite. — Monoclinic. Composition like epidote, but with Mn replacing some A1 and Fe. Specific gravity, 3.4. Color, reddish brown to black. Hardness, 6.5. Allanite or orthite. — Monoclinic. Composition like epidote, but with cerium earths partly replacing alumina and iron. Specific grav- ity, 3.5 to 4.2. Color, brown to black. Hardness, 5.5 to 6. The reported syntheses of zoisite and epidote are questionable, for the products seem to have contained no water. A. Brun 7 claimed to have produced zoisite by fusing 40 parts of silica with 37 of lime and 23 of alumina. C. Doelter, 8 upon fusing epidote powder with the fluorides of sodium and calcium, obtained indications of some recrystallization of the epidote, together with garnet, meionite, anor- 1 See H. Bucking, Ber. Senckenbergischen naturforsch. Gesell., Abhandl., 1900, p. 3; J. Szab<5, Neues Jahrb., Beil. Band 1, 1881, p. 308; E. Hussak, Sitzungsb. K. Akad. Wiss. Wien, vol. 87, Abth. 1, 1883, p. 332; Neues Jahrb., 1885, Band 2, p. 81; A. Harker, Geol. Mag., 1906, p. 176. 2 Am. Jour. Sci., 3d ser., vol. 36, 1888, p. 57. 3 Loc. cit. 4 Jour. Coll. Sci. Japan, vol. 3, 1890, p. 313. Kikuchi also describes an alteration of the iolite into pinite. 5 For a summary of these alterations see A. Wichmann, Zeitschr. Deutsch. geol. Gesell., vol. 26, 1874, p. 675. For the mechanism of the change from iolite to chlorophyllite see F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914, p. 79. 6 Foroptical variations in zoisite, see P. Termier, Bull. Soc. min., vol. 21, 1898, p. 148; vol. 23, 1900, p. 50. Termier regards the silicate HCa 2 R ,,, 3 Si 30 i 3 as trimorphous. 7 Arch. sci. phys. nat., 3d ser., vol. 25, 1891, p. 239. 8 Neues Jahrb., 1897, Band 1, p. 1. ROCK-FORMING MINERALS. 407 thite, olivine, and magnetite. Epidote fused alone gave anorthite and a lime augite. Satisfactory syntheses of the minerals forming this group are yet to be made. Zoisite is essentially a mineral of the crystalline schists, such as amphibolite, glaucophane schist, eclogite, etc. It is also found in some granites and in beds of sulphide ores. A secondary zoisite, derived from plagioclase and commonly containing both minerals commingled, is known as saussurite and is common in gabbros . 1 It is not at all uniform in composition. Epidote, like zoisite, is a mineral of the crystalline schists, although C. R. Keyes 2 has cited evidence to show that it is a primary mineral in certain granites of Maryland. It is there intergrown with allanite and was also observed inclosed in primary sphene. A. Michel-Levy 3 also regards the epidote of certain Pyrenean ophites as primary. It is also found, according to B. S. Butler , 4 in dikes cutting soda granite porphyry in Shasta County, California. There are many other examples on record. Epidote is common in gneisses, garnet rock, amphibolite, parag- onite and glaucophane schists, and the phyllites, and as a contact mineral in limestones. It is also common as a secondary mineral, derived from feldspars, pyroxene, amphibole, biotite, scapolite, and garnet, and is frequently associated with chlorite. When lime-bear- ing ferromagnesian minerals chloritize their lime goes to the produc- tion of epidote. An epidote-quartz rock derived from diabase has been called epidosyte . 5 Piedmontite is much less abundant than zoisite or epidote and is mainly confined to the crystalline schists. It also occurs with iron ores and as a secondary mineral in eruptives. G. H. Williams 6 has re- ported piedmontite in a rhyolite from Pennsylvania and N. Yamasaki 7 has described a similar occurrence in Japan. Piedmontite is quite com- mon in the crystalline schists of Japan , 8 forming a piedmontite schist, and also associated with rocks containing chlorite or glaucophane. Allanite is widely diffused as a primary accessory in many igneous rocks. J. P. Iddings and W. Cross , 9 who have pointed out its importance, cite occurrences of allanite in gneiss, granite, quartz 1 Also in the greenstones of the Lake Superior region. See G. H. Williams, Bull. U. S. Geol. Survey No. 62, 1890, where the process of saussuritization is discussed. Williams cites abundant references to the literature of the subject. 2 Bull. Geol. Soc. America, vol. 4, 1893, p. 305. 3 Bull. Soc. g§ol. France, 3d ser., vol. 6, p 161. 4 Am. Jour. Sci., 4th ser., vol. 28, 1909, p. 27. Butler gives many references to literature. s For a discussion of this alteration, with references to literature, see A. Schenck, Doct. Diss., Bonn, 1884. Williams, in Bull. U. S. Geol. Survey No. 62, 1890, also discusses the process of epidotization some- what fully. 6 Am. Jour Sci., 3d ser., vol. 46, 1893, p. 50. This paper contains many references to literature. 7 Jour. Coll. Sci. Japan, vol. 9, 1897, p. 117. 8 See B. Koto, idem, vol. 1, 1887, p. 303. 8 Am. Jour. Sci., 3d ser., vol. 30, 1885, p. 108. 408 THE DATA OF GEOCHEMISTRY. porphyry, diorite, andesite, dacite, rhyolite, etc. W. H. Hobbs, 1 study- ing the granite of Ilchester, Maryland, in which allanite and epidote are intergrown, has especially discussed the paragenesis of the two species. The same association of minerals has been reported by F. D. Adams, 2 A. Lacroix, 3 G. H. Williams, 4 and others. In the granite of Pont Paul, France, allanite is sometimes enveloped by biotite. 5 W. Mackie 6 has reported several occurrences of allanite in Scottish granites. Allanite is often much altered, yielding car- bonates of the cerium group, together with earthy products of uncer- tain character. TOPAZ. Orthorhombic. Simplest empirical formula, Al 2 Si0 4 F 2 , but with part of the fluorine commonly replaced by hydroxyl. 7 Molecular weight, 184.6. Specific gravity, 3.56. Molecular volume, 51.9 Color, white, yellow, greenish, bluish, and reddish. Hardness, 8. The true formula is probably three times that given above, with the molecular weight and volume correspondingly tripled. 8 The synthesis of a product allied to topaz was early reported by A. Daubree, 9 who heated alumina in a current of silicon fluoride. It contained, however, too little fluorine, and varied in other respects from topaz. H. Sainte-Claire Deville, 10 repeating the experiment, obtained no fluoriferous silicate. C. Friedel and E. Sarasin 11 claim to have prepared topaz by heating alumina, silica, water, and hydrofluo- silicic acid together at 500°, but give no details nor analyses. A. Keich 12 subjected a mixture of silica and aluminum fluoride to a strong red heat, and afterwards ignited the mixture thus obtained in a current of silicon fluoride. By this process topaz was formed, which was identified both crystallographically and by analysis. This is the only satisfactory synthesis of topaz so far recorded. Topaz commonly occurs in gneiss or granite, and especially in tin- bearing pegmatites. The rock from the tin mine at Mount Bischoff, Tasmania, has been described by A. von Groddeok 13 as a porphyritic topazfels. The Brazilian topazes are found in decomposed material, 1 Am. Jour. Sci., 3d ser., vol. 30, 1885, p. 108; vol. 38, 1889, p. 223. 2 Canadian Rec. Sci., vol. 4, 1891, p. 344. * 3 Bull. Soc. min., vol. 12, 1889, pp. 138, 157, 210. 4 Bull. U. S. Geol. Survey No. 62, 1890. 6 A. Michel-Levy and A. Lacroix, Bull. Soc. min., vol. 11, 1888, p. 65. e Trans. Edinburgh Geol. Soc., vol. 9, 1909, p. 216. A Canadian “granite," containing 56 per cent of allanite, is reported by G. C. Hoffmann in Ann. Kept. Geol. Survey Canada, vol. 7, 1894, p. 12R. 7 S. L. Penfield and J. C. Minor, Am. Jour. Sci., 3d ser., vol. 47, 1894, p. 387. 8 See F. W. Clarke and J. S. Diller, Bull. U. S. Geol. Survey No. 27, 1886, and also Clarke, Bull. No. 588, 1914 % 9 Etudes synthetiques de gfiologie experimental, p. 57. 10 Compt. Rend., vol. 52, 1861, p. 780. 11 Bull. Soc. min., vol. 10, 1887, p. 169. 12 Monatsh. Chemie, vol. 17, 1896, p. 149. 1 3 Zeitschr. Deutsch. geol. Gesell., vol. 36, 1884, p. 642. On the topaz-bearing rocks of Gunong Bakau, Malay States, seo J. B. Scrivenor, Quart. Jour. Geol. Soc., vol. 70, 1914, p. 363. ROCK-FORMING MINERALS. 409 which, according to O. A. Derby, 1 was probably a mica schist derived from an antecedent augite or nepheline syenite. In Colorado and Utah topaz occurs in litbophyses of rhyolite. 2 Gaseous emanations containing fluorine probably play an important part in its develop- ment. Topaz alters easily, by hydration and by the action of perco- lating alkaline solutions, and is transformed into compact muscovite. 3 The reported alterations to steatite and serpentine are probably based upon erroneous diagnoses. By heating topaz with a solution of sodium silicate 174 hours at 200° to 210°, J. Lemberg 4 converted it into an alkaline alumo-silicate of presumably zeolitic character. At a white heat topaz loses fluorine and becomes transformed into sillimanite. 5 THE AND ALU SITE GROUP. Andalusite. — Orthorhombic. Simplest empirical formula, Al 2 Si0 5 ; true formula probably three times as great. Corresponding molecular weight, 162.6. Specific gravity, 3.18. Molecular volume, 51.1. Color, white, reddish, violet, brown, olive-green. Hardness, 7.5. Sillimanite or fibrolite. — Orthorhombic. Composition and lowest molecular weight the same as for andalusite. Specific gravity, 3.2. Molecular volume, 50.8. Color, grayish white, grayish brown, pale green, brown. Hardness, 6 to 7. Kyanite or cyanite. — Triclinic. Composition, etc., as with anda- lusite and sillimanite. Specific gravity, 3.6. Molecular volume, 45.2. Color, commonly blue, sometimes white, gray, or green. Hardness, 7. These three minerals are of peculiar interest because of their iden- tity in chemical composition. They undoubtedly differ in chemical structure, and kyanite possibly differs from the other two in molecu- lar weight, but upon the latter point the evidence is not conclusive. Andalusite and sillimanite are commonly regarded as basic ortho- silicates, and kyanite, on account of its greater resistance to the action of acids, has been interpreted by P. Groth as a metasilicate, (A10) 2 Si0 3 . 6 In an interesting investigation by W. Vernadsky 7 it is shown that both andalusite and kyanite are transformed into sillimanite by simply heating to a temperature between 1,320° and 1,380°. Sillimanite, therefore, is the most stable of the three species, at least under pyrogenic conditions. Vernadsky has identified it as 1 Am. Jour. Sci., 4th ser., vol. 11, 1901, p. 25. 2 See W. Cross, idem, 3d ser., voi. 31, 1886, p. 432. 3 For a complete study of this alteration, see F. W. Clarke and J. S. Diller, Bull. U. S. Geol. Survey No. 27, 1886. See also A. Atterberg, Geol. Foren. Forhandl., vol. 2, 1874-75, p. 402. 4 Zeitschr. Deutsch. geol. Gesell., vol. 40, 1888, pp. 651 et seq. 5 W. Vernadsky, Bull. Soc. min., vol. 13, 1890, pp. 259-260. 6 A different but not very plausible interpretation of these species has been offered by K. Zulkowski, Monatsh. Chemie, vol. 21, 1900, p. 1086. 7 Bull. Soc. min., vol, 13, 1890, p. 256; Compt. Rend., vol. 110, 1890, p. 1377. For earlier syntheses of these minerals, by Daubrde, Deville and Caron, Fremy and Feil, Meunier, and Hautefeuille and Margottet, see L. Bourgeois, Reproduction artificielle des mindraux, pp. 119, 120. The processes, except the last, involved the use of aluminum fluoride, silicon fluoride, or silicon chloride, and were therefore indirect. 410 THE DATA OF GEOCHEMISTBY. an essential constituent of hard porcelain. He also obtained silli- manite by fusing silica and alumina together. This synthesis has also been effected by E. S. Shepherd and G. A. Rankin, 1 who find that sillimanite is the only one of the three silicates which is stable in the pure melt. They also confirm the statement that kyanite and andalusite pass into sillimanite when strongly heated. Their arti- ficial sillimanite melted at 1,811°. A. Reich, 2 by heating aluminum fluoride with silica to strong redness, obtained a mixture of silli- manite and corundum. The conditions under which sillimanite can form magmatically have also been determined by J. Morozewicz. 3 In the magmatic mixture R0.mAl 2 0 3 . / ?iSi0 2 , if magnesia and iron are absent, m = 1, and n is greater than 6, sillimanite is developed. K. Dalmer 4 has reported the alteration of a chlorite-mica phyllite into a mixture of andalusite and biotit e. Andalusite is a mineral of the metamorphic schists, and is espe- cially common in the contact zones of clay slate near dikes of granite or diorite. It is also found in Archean gneiss and mica schist, and sometimes as an accessory in graifite. Sillimanite is common in the crystalline schists, particularly in feldspathic gneiss, and in cordierite gneiss. It is often found inter- grown with quartz. Kyanite also occurs in crystalline schists, such as gneiss, mica schist, paragonite schist, and eclogite. It is often embedded in quartz, and has been reported in limestone. 5 Andalusite alters to muscovite, 6 and sometimes also to chlorite and kaolin. 7 J. Lemberg, 8 by heating andalusite or kyanite with alkaline silicates or carbonates under pressure, converted them into zeolitic substances. C. Doelter, 9 upon heating andalusite with potassium carbonate and fluoride during several weeks at 250°, observed the formation of scales of mica. It has already been stated that the empirical formulae for topaz and andalusite should probably be tripled, a suggestion which is based partly upon their alterability into muscovite. On this basis the three species compare as follows: Andalusite Al 3 (Si0 4 )3(A10) 3 . Topaz Al 3 (Si0 4 )3(AlF 2 )3. Muscovite Al 3 (Si0 4 ) 3 KH 2 . 1 Am. Jour. Sci., 4th ser., vol. 28, 1900, p. 293. See also W. Eitel, Zeitschr. anorg. Chem., vol. 88, 1914, p. 173. 2 Monatsh. Chemie, vol. 17, 1896, p. 190. 3 Min. pet. Mitt., vol. 18, 1898, p. 72. * Neues Jahrb., 1897, Band 2, p. 156. 5 J. Kovaf, Zeitschr. Kryst. Min., vol. 34, 1901, p. 704. « A. Gramann, Neues Jahrb., Bd. 2, 1901, p. 193. 7 P. E. Haefele, Zeitschr. Kryst. Min., vol. 23, 1894, p. 551. 8 Zeitschr. Deutsch. geol. Gesell., vol. 40, 1888, p. 651. 9 Allgemeine chemische Mineralogie, p. 207. •> ROCK-FORMING MINERALS. 411 STAUROLITE. Orthorhombic. Composition, HFeAl 5 Si 2 0 13 , 1 with a little mag- nesia or sometimes manganese oxide replacing a part of the iron. Molecular weight, 457.2. Specific gravity, 3.7. Molecular volume, 123. Color, brown to black. Hardness, 7 to 7.5. No authentic synthesis of staurolite has yet been recorded. The substance obtained by H. Sainte-Claire Deville and H. Caron, 2 by the action of silicon fluoride upon a heated mixture of alumina and quartz, and called staurolite by them, had nearly the composition of sillimanite. 3 P. Hautefeuille and J. Margottet, 4 in their memoir upon the synthesis of certain phosphates, also mention the produc- tion of a mineral resembling staurolite hut give no further details. Staurolite is a mineral of the metamorphic schists, especially of muscovite or paragonite schist, and some gneisses or slates. It is often associated with kyanite. Staurolite alters into muscovite. 5 The reported alteration into steatite is very questionable. LAWSONITE. Orthorhombic. Composition, H 4 CaAl 2 Si 2 O 10 . Molecular weight, 315.1. Specific gravity, 3.09. Molecular volume, 102. Color, pale blue to grayish blue. Hardness, 8.25. Lawsonite was discovered by F. L. Ransome 6 in 1895, in a glauco- phane-bearing schist from Tiburon Peninsula, California. It has since been found by S. Franchi and A. Stella 7 in the metamorphic schists of the Alps; by C. Viola 8 in the saussuritized gabbros of southern Italy; and by A. Lacroix 9 in similar rocks and glauco- phane schists from Corsica and New Caledonia. J. P. Smith 10 has recently described lawsonite rocks from several localities in Cali- fornia, especially a lawsonite-glaucophane schist and a lawsonite- glaucophane gneiss. The latter rock carried about 25 per cent of lawsonite. The mineral is evidently of widespread occurrence. Its formula suggests a derivation from anorthite, by assumption of two molecules of water. Upon fusion, lawsonite would undoubtedly yield anorthite. 1 Established by S. L. Penfield and J. H. Pratt, Am. Jour. Sci., 3d ser., vol. 47, 1894, p. 81. 2 Compt. Rend., vol. 46, 1858, p. 764. a H. Sainte-Claire Deville, idem, vol. 52, 1861, p. 780. * Idem, vol. 96, 1883, p. 1052. e See analysis in Bull. U. S. Geol. Survey No. 220, 1903, p. 54. ® Bull. Dept. Geology Univ. California, vol. 1,1895, p. 301. See also F. L. Ransome and C. Palache, Zeitschr. Kryst. Min., vol. 25, 1896, p. 531; and W. T. Schaller and W. F. Hillebrand, Bull. U. S. Geol. Survey No. 262, 1905, p. 58. 7 Cited by P. Termier, Bull. Soc. min., vol. 20, 1897, p. 5. See also Termier, idem, vol. 27, 1904, p. 265. s Zeitschr. Kryst. Min., vol. 28, 1897, p. 553. 9 Bull. Soc. min., vol. 20, 1897, p. 309. 10 Proc. Am. Philos. Soc., vol. 45, 1907, p. 183. See also A. S. Eakle, Bull. Dept. Geology Univ. Cali- fornia, vol. 5, 1907, p. 82. 412 THE DATA OF GEOCHEMISTRY. According to F. Cornu/ the compound H 4 CaAl 2 Si20 9 is dimor- phous. Lawsonite is one modification; the other, isometric, he has named hibschite. It was found enveloping garnet as an inclusion in the phonolite of Aussig, Bohemia. DUM ORTIERITE. Orthorhombic. Composition, Al 8 HBSi 3 O 20 . 1 2 Molecular weight, 634. Specific gravity, 3.3. Molecular volume, 192. Color, blue, bluish green, lavender, or black. Hardness, 7. Dumortierite was originally discovered in a pegmatite gneiss near Lyons, in France. It has since been found in Germany, Austria, Norway, Argentina, and at several localities in the United States. 3 It has been observed in pegmatite, in cordierite gneiss, 4 in granite, and in certain quartz rocks associated with kyanite (Arizona), sil- limanite (California), and andalusite (Washington). Muscovite is also one of its companions, and Schaller has observed its alteration into muscovite. It is an inconspicuous mineral, except for its usual bright-blue color, and is probably not at all rare. Its close relation- ship to andalusite, sillimanite, and kyanite is obvious. According to W. Vernadsky, 5 dumortierite, at a white heat, is converted into sillimanite. What other product is formed at the same time is not stated. 6 TOURMALINE. Rhombohedral. Composition, a complex borosilicate of aluminum and other bases. Color, white, yellow, brown, green, red, blue, and black. Specific gravity, 2.98 to 3.20. Hardness, 7 to 7.5. Tourmaline really represents a group of isomorphous species, whose chemical relations are not yet completely understood. There are, however, three distinct types, as follows: Alkali tourmaline: Contains lithium or sodium, sometimes potas- sium in less amount. Found in pegmatites, with muscovite and lepidolite. Magnesium tourmaline: Chief base, after aluminum, magnesium. Often found in limestone or dolomite, with phlogopite as the accom- panying mica. Iron tourmaline: The common black variety, which alone is signifi- cant as a rock-making mineral. Contains iron in place of magne- sium. Associated commonly with muscovite or biotite. 1 Min. pet. Mitt., vol. 25, 1906, p. 249. 2 As determined by W. T. Schaller, Bull. U. S. Geol. Survey No. 262, 1905, pp. 91-120. See also W. E. Ford, Am. Jour. Sci., 4th ser., vol. 4, 1902, p. 426. Ford’s formula differs slightly from Schaller’s. 3 See Schaller’s memoir, cited above, for a full summary of the known localities and a bibliography of the species. 4 See A. Lacroix, Bull. Soc. min., vol. 12, 1889, p. 211. 6 Idem, vol. 13, 1890, p. 256. 6 Q. I. Finlay (Jour. Geology, vol. 15, 1907, p. 479) reports dumortierite and corundum as original pyro- genic constituents of a pegmatite dike near Canon City. Colorado. ROCK-FORMING MINERALS. 413 Between these distinct types there are various intermediate mix- tures, and also rare examples in which a little chromium appears, partly replacing aluminum. Over the chemical formula of tourmaline there has been much dis- cussion, and no set of expressions can be assumed as final. 1 The following formulae seem to be best sustained by evidence: 2 (1) AlgR/gSisBgOgx. (2) AfiR^SigBgOgx. (3) AfiR/^SieBgOgj. In No. 3 the B/ is largely replaced by R", which may he Fe or Mg. Hydrogen is important among the components of R'. Fluorine is also commonly present in small amounts. The general formula Al 3 R 9 (B0H) 2 Si 4 0 19 , proposed by S. L. Penfield and H. W. Foote, 3 is preferred by some authorities. Tourmaline has not as yet been produced synthetically. The rock- forming iron-hearing variety is commonly found in the older and more highly siliceous igneous and granular rocks, such as granite, syenite, and diorite. It is also abundant in mica schists, clay slates, and other similar matrices. It forms in some cases at the contact between schists and granite, and may be abundant enough to characterize an occurrence as a tourmaline hornstone. In igneous rocks it seems to have been produced by fumarole action, and not as a direct separation from the magma. H. B. Patton 4 regards the tourmaline of certain schists in Colorado as having been formed at the expense of the bio- tite contained in the pegmatites adjoining the contact zone. Tourmaline alters to mica, chlorite, and cookeite. Upon fusion, according to C. Doelter, 5 tourmaline yields olivine and spinel. BERYL. Hexagonal. Normal composition, Al 2 Gl 3 Si 6 0 18 . Molecular weight, 539.9. Specific gravity, 2.7. Molecular volume, 200. Colorless, white, more commonly green, sometimes yellow, blue, or rose. Hard- ness, 7.5 to 8. Although normal beryl has the composition given above, the min- eral generally varies from it. S. L. Penfield 6 has shown that many beryls contain alkalies, replacing glucina, and also some combined 1 See C. Rammelsberg, Neues Jahrb., 1890, Band 2, p. 149. A. Kenngott, idem, 1892, Band 2, p. 44. G. Tschermak, Min. pet. Mitt., vol. 19, 1899, p. 155; Zeitschr. Kryst. Min., vol. 35, 1899, p. 206. V. Gold- schmidt, Zeitschr. Kryst. Min., vol. 17, 1890, pp. 52, 61. R. Scharizer, idem, vol. 15, 1889, p. 337. P. Jannasch and G. Calb, Ber. Deutsch. chem. Gesell., vol. 22, 1889, p. 216. H. Rheineck, Zeitschr. Kryst. Min., vol. 17, 1890, p. 604; vol. 22, 1894, p. 52. E. A. Wiilfing, Min. pet. Mitt., vol. 10, 1888, p. 161; Reiner, Inaug. Diss. Heidelberg, 1913; W. T. Schaller, Zeitschr. Kryst. Min., vol. 51, p. 321, 1913. 2 Bull. U. S. Geol. Survey No. 167, 1900, p. 26; Am. Jour. Sci., 4th ser., vol. 8, 1899, p. 111. Also in Bull. U. S. Geol. Survey No. 588, 1914. s Am. Jour. Sci., 4th ser., vol. 7, 1899, p. 97; vol. 10, 1900, p. 19. * Bull. Geol. Soc. America, vol. 10, 1898, p. 21. 6 Neues Jahrb., 1897, Band 1, p. 1. 6 Am. Jour. Sci., 3d ser., vol. 28, 1884, p. 25; vol. 36, 1888, p. 317. 414 THE DATA OF GEOCHEMISTRY. water, up to nearly 3 per cent. A beryl from Hebron, Maine, con- tained 3.60 per cent of Cs 2 0. A beryl analyzed by J. S. De Benne- ville 1 carried 2.76 per cent of K 2 0; and F. C. Robinson, 2 in another example, found 2.76 per cent of P 2 0 5 . J. J. Ebelmen 3 succeeded in recrystallizing beryl by fusion with boric oxide. P. Hautefeuille and A. Perrey 4 obtained it in crystals by fusing a mixture of alumina, glucina, and silica with the same flux. H. Traube 5 precipitated a solution containing aluminum sul- phate and glucinum sulphate with sodium metasilicate, and crystal- lized the product from fused boric oxide in the same way. In both of the cases just cited, the beryl obtained was identified crystallo- graphically and by analysis. Beryl is a common accessory in pegmatite veins. It is also found in clay slate and mica schist. It alters into mica and kaolin, when the removed glucina generally appears as a constituent of other secondary minerals, such as bertrandite, herderite, or beryllonite. Although beryl is not commonly included by petrographers in their lists of rock-forming minerals, it seems entitled to recognition in a chapter of this kind. SERPENTINE, TALC, AND KAOLINITE. Serpentine . — Optically monoclinic, but not known in true crystals. Composition, H 4 Mg 3 Si 2 0 9 . Molecular weight, 278. Specific grav- ity, 2.5 to 2.6. Molecular volume. 109. Color commonly green, often yellowish. Hydrous magnesian silicates are easily prepared by various wet reactions, but these syntheses have little or no significance in the interpretation of serpentine. 6 The mineral occurs in nature only as a secondary product, derived by hydrous alteration from olivine, hornblende, actinolite, enstatite, diopside, chondrodite, and other magnesian minerals. Large rock masses are frequently found which have become transformed into impure serpentine. Gabbro, 7 perido- tite, 8 and amphibolite 9 may undergo this change. 10 The alterative process, however, does not end here. Serpentine itself may undergo further alteration, yielding brucite, magnesite, hydromagnesite, etc. R. Brauns 11 has described a derivative of serpentine, which he calls » Jour. Am. Chem. Soc., vol. 16, 1894, p. 65. 2 Jour. Anal, and Appl. Chem., vol. 6, 1892, p. 510. 3 Annales chim. phys., 3d ser., vol. 22, 1848, p. 237. * Compt. Rend., vol. 106, 1888, p. 1800. 6 Neues Jahrb., 1894, Band 1, p. 275. 6 See, for example, A. Gages, Rept. Brit. Assoc., 1863, p. 203. Gage’s product resembled deweylite. 2 See L. Finckh, Zeitschr. Deutsch. geol. Gesell., vol. 50, 1898, p. 108. 8 See G. H. Williams, Am. Jour. Sci., 3d ser., vol. 34, 1887, p. 137. 9 See J. B. Jaquet, Rec. Geol. Survey New South Wales, vol. 5, 1905, p. 18. 10 For general discussion over the origin of serpentine, see G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, pp. 108 et seq.; and J. J. H. Teall, British petrography. The literature is very abundant. 11 Neues Jahrb., Beil. Band 5, 1887, p. 318. Brauns discusses the different varieties of serpentine fully and cites much literature. BOCK-FORMING MINERALS. 415 webskyite, H 6 Mg 4 Si 3 0 13 .6H 2 0; and F. W. Clarke 1 has reported an apparent serpentine which proved upon analysis to be nearly 60 per cent brucite. By solfataric action serpentine may lose its magnesia in the forms of sulphate or carbonate and become transformed into a mass of quartz and opal. 2 When serpentine is fused it yields a mix- ture of olivine and enstatite. 3 Talc. — Monoclinic. Composition, H 2 Mg 3 Si 4 C 12 . Molecular weight, 380.8. Specific gravity, 2.7 to 2.8. Molecular volume, 138. Color, white to green. The name talc is commonly applied to the foliated varieties; the massive mineral is called steatite. Talc is common as a pseudomorphous mineral, derived from other magnesian species, often from tremolite or enstatite. 4 Assuming the change to be brought about by carbonated water, the reactions may be simply written as follows : . CaMg 3 Si 4 0 12 + H 2 0 + C0 2 = H 2 Mg 3 Si 4 0 12 + CaC0 3 . Mg 4 Si 4 0 12 + H 2 0 + C0 2 = H 2 Mg 3 Si 4 0 12 + MgC0 3 . The talc thus produced is not infrequently associated with marble or dolomite. The most important occurrence of talc, however, from a geological point of view, is in the form of talcose schist. According to F. A. Genth, talc may alter into anthophyllite. 5 When talc is ignited, it loses water, and one-fourth of the silica is split off in the free state. 6 The residue after removing the liberated silica, has the composition MgSi0 3 . A number of other hydrous magnesian silicates occur as secondary minerals, such as deweylite, saponite, etc.; but they are geologically unimportant. Kaolinite. — Monoclinic. Composition, H 4 Al 2 Si 2 0 9 . Molecular weight, 259. Specific gravity, 2.6. Molecular volume, 99.6. Color, white, often tinted by impurities. Known only as a secondary mineral, the product of hydrous alter- ation of other species. Derived chiefly from feldspars. Halloysite, cimolite, newtonite, montmorillonite, pyrophyllite, and allophane are other hydrous silicates of aluminum. They need no consideration here. 1 Bull. U. S. Geol. Survey No. 262, 1905, p. 69. 2 See G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, pp. 108 etseq.; also A. Lacroix, Compt. Bend, vol. 124, 1897, p. 513. 3 Daubr6e; see ante, p. 376, under enstatite. 4 See C. H. Smyth, School of Mines Quart., vol. 17, 1896, p. 333, and J. H. Pratt, North Carolina Geol. Survey, Economic Paper No. 3. 6 Proc. Am. Philos. Soc., vol. 20, 1882, p. 381. 6 F. W. Clarke and E. A. Schneider, Bull. U. S. Geol. Survey No. 78, 1891, p. 13. 416 THE DATA OF GEOCHEMISTRY. THE ZEOEXTES. Under the general term zeolites are included a number of impor- tant minerals, which, however, do not strictly belong to the rock- making class. They occur in eruptive rocks only as secondary prod- ucts, except in the noteworthy case of analcite, which has already been described. The more important zeolites are the following: Heulandite Stilbite Laumontite Chabazite Thomsonite Scolecite Natrolite Hydronephelite. CaAbSi^O 16 . 5H 2 0 . CaAl 2 Si 58. 09 16. 68J 10. 92] 3. 56] 1 . 86 ] . 46] .24] • 31] .85 14. 48 2. 32 .55 99. 27 99. 15 428 THE DATA OF GEOCHEMISTRY. The divergence between convention and reality is evident at a glance. In many cases, however, the norm and mode of a rock are practically identical, and then the standard computation is more satisfactory. The normative and actual minerals may or may not be the same. Some discrepancies, however, exist, to which much weight can not be given. In calculating the percentage of a mineral from the proportions of oxides shown by analysis there is a strong tendency toward the multiplication of errors. Alumina, for instance, is often uncertain, at least in ordinary analyses of fair average quality, by as much as one-half of 1 per cent. This amount corresponds to an error in orthoclase, if all the alumina goes to that mineral, of 2.7 per cent, and the variation entrains others, especially in the estimation of the residual quartz. The computed mineral composition of a rock is incorrect by multiples of the errors existing in the analysis, and these may be, in fact are, sometimes large. The normative or standard minerals, then, so far as the make-up of a rock is concerned, are partly real and partly conventional. They are, however, quantitative in application and give uniformity to the discussion of rocks. Upon them the quantitative classification is founded. First, all igneous rocks are divided into five classes , which are fixed within certain arbitrary limits by the ratios between the salic and femic minerals. These classes are as follows: I. Persalane: Extremely salic II. Dosalane: Dominantly salic III. Salfemane: Equally salic and femic IV. Dofemane: Dominantly femic V. Perfemane: Extremely femic That is, the field between an entirely salic rock and one entirely femic is divided into five parts, each representing a definite range of variation. A rock containing more than seven-eighths of salic min- erals to one-eighth femic is in the class persalane ; one with less than seven-eighths salic to more than three-eighths femic falls under dosalane, and so on. A granite, for example, containing over 87.5 per cent of quartz and feldspar is placed in Class I; a peridotite with over 87.5 per cent of femic minerals belongs in Class V. Many basalts, gabbros, diorites, etc., contain salic and femic compounds in nearly equal proportions, and are therefore in Class III. From the norm of a rock its class can be determined at once, and in many cases a mere inspection of the analysis is sufficient. The two extreme sal .. 7 fem ^ 1 sal .7^5 fem ^ 1 > 3 sal ^.5^3 fem <_ 3 _> T sal 3.1 fem ^ 5 ^ 7 sal ^ 1 fem ^ 7 IGNEOUS ROCKS. 429 classes occupy each one-eighth of the field; the other classes divide the remaining six-eighths between them. The division of classes into subclasses is based upon a previous division among the standard minerals themselves. Thus the salic minerals are grouped as quartz, Q; feldspar, F; lenads, or feld- spathoids, L; corundum, C; and zircon, Z. Q, F, and L are placed together as one subclass; C and Z as another. In the femic series we have, first, pyroxenes, P; olivine and akermanite, O; with the group of iron ores and titanium minerals, M; and, second, the acces- sories apatite, fluorite, pyrite, etc., represented by A. In Classes I to III the subdivision is effected through the ratio QFL to CZ by the same fivefold process, one-eighth, two-eighths, and so on, as in the formation of classes themselves. In Classes IV and V, the dofemic and perfemic, the ratio POM to A is used in precisely the same way. There are therefore twenty-five subclasses, but the vast majority of igneous rocks belong to the first subclass in each class. These are indicated by the expressions — QFL 7 , ~CZ >I and POM 7 A > 1 the minerals thus given prominence being those which make up the greater part of the lithosphere. Pocks in which C, Z, or A abound are not common, and their distribution or volume is extremely limited. After the subclasses come the orders , which are formed according to the proportions, in the rocks, of the preponderating minerals. In Classes I to III the salic minerals are used as a basis for subdivision, and the ratios connecting Q, F, and L are alone considered. Quartz and the lenads, however, are chemically antithetic, and do not occur together; and this leads to a doubling of the ordinary fivefold divi- sion of a class, with one term dropped out. That is, each class is divided into nine orders; if there were ten, the fifth and sixth would practically, although not absolutely, repeat each other. These orders are as follows : 1. Perquaric: Quartz extreme 2. Doquaric: Quartz dominant 3. Quarfelic: Equal quartz and feldspar. 4. Quardofelic: Feldspar dominant 5. Perfelic: Feldspar extreme. F 430 THE DATA OF GEOCHEMISTEY. 6. Lendofelic: Feldspar dominant 7. Lenfelic: Equal feldspar and lenad 8. Dolenic: Lenad dominant 9. Perlenic: Lenad extreme F 1 In Classes IV and V the f emic ratio P + O : M is used to designate the orders. They are: P+O 7 1. Perpolic: Silicate extreme >— M 1 P +0 7 5 2. Lopolic: Silicate dominant < — > — M 13 P +0 5 3 3. Polmitic: Silicate and nonsilicate equal < — >— M 3 5 P+O 3 1 4. Domitic: Nonsilicate dominant < — > M 5 7 P+O 1 5. Permitic: Nonsilicate extreme < — M 7 In orders 1 to 3 there is also a precisely similar fivefold division into sections, which indicate the proportions between pyroxenes and the olivine subgroup. In orders 4 and 5 a like subdivision into sub- orders is based upon the ratio H : T, hematite plus magnetite on the one hand and the titanium minerals ilmenite, titanite, perofskite, and rutile on the other. It is not necessary for present purposes to carry these subdivisions out in detail, for the ratios are expressed by precisely the same fractions as appear in the classes and orders. Up to this point the quantitative classification has been mineral- ogical, and expressed in terms of the standard or normative minerals. The division of orders into rangs , however, proceeds on chemical lines, but is still fivefold as before. In Classes I to III, which are characterized by feldspars and lenads, the molecular ratio of salic K 2 0 + Na 2 0 to salio CaO is the determining factor. In Classes IV and V the molecular ratio of f emic CaO + (MgFe) O to femio alkalies is considered. By salio CaO is meant the lime in salio minerals, such as anorthite; femic lime is that in diopside, wollastonite, etc. Salio alkalies are found in feldspars and lenads; femio alkalies occur in acmite and certain other pyroxenes and amphiboles. In the par- tition of actual minerals, such as the micas, between the two norma- tive groups, the potash of muscovite will go to the salic side, while that of biotite is regarded as femic. Now, uniting K 2 0 and Na 2 0 IGNEOUS ROCKS. 431 under the general symbol of R 2 0, the rangs under the orders of Classes I to III develop thus: R 2 0 7 1. Peralkalic . > CaO 1 R 2 0 7 5 2. Domalkalic < > CaO 1 3 R 2 0 5 3 3. Alkalicalcic < > CaO 3 5 R 2 0 3 1 4. Docalcic < — > — CaO 5 7 R 2 0 1 5. Percalcic < CaO 7 The nomenclature here would seem to be self-explanatory, but in Classes IV and V a less obvious device is proposed, namely, to indi- cate magnesium, iron, and Zime the word mirlic is suggested. Unit- ing MgO, FeO, and CaO under the symbol RO we now have in the distinctively f emic classes these rangs : RO 7 1. Permirlic > R 2 0 1 RO 7 5 2. Domirlic < — > R 2 0 1 3 RO 5 3 3. Alkalimirlic < — > — R 2 0 3 5 RO 3 1 4. Domalkalic < — > R 2 0 5 7 RO 1 5. Peralkalic.... < R 2 0 7 The femio rangs are again subjected to a fivefold subdivision into sections, depending upon the ratio (MgFe) O to CaO; and they are also divided into subrang s which indicate the ratio between magnesia and ferrous oxide. So also, in Classes I to III there are subrangs based upon the alkalies alone, and these are called, respectively, per- potassic, dopotassic, sodipotassic, dosodic, and persodic. These sub- rangs are still further divisible in such manner as to show the ratios between the lenad minerals leucite and ncphelite, and sodalite and noselite, and either of these pairs may be subdivided in the same way. In some of these cases a threefold division is employed instead of the usual method. In Classes II, III, and IV the rangs are again divided into grads , which serve to classify the subordinate minerals. In Classes II and III the subordinate femic group is divided accord- ing to the ratio P + O to M, just as in forming the orders of Classes 432 THE DATA OF GEOCHEMISTRY. IV and V. In Class IV the subordinate salic minerals serve to designate five grads, depending upon the relations between quartz, feldspars, and lenads. In Class III there is also a threefold discrim- ination between pyroxene and olivine, forming the sections prepyric, pyrolic, and preolic. Furthermore, precisely as rangs are formed within orders, so subgrads are formed within grads. That is, the ratios RO to R 2 0; R 2 0 to CaO; (MgFe) O to CaO; and MgO to FeO are used to express between subordinate minerals the same relations that hold in forming the larger divisions of the classification. The quantitative classification, then, takes pairs of factors, and divides each pair, with a few limitations only, into five terms, expressive of different ratios. This process, obviously, can be car- ried out to any desired degree of minuteness; but for most practical purposes four subdivisions are generally enough. These may be stated as classes, orders, rangs, and subrangs; the subclasses, sub- orders, grads, etc., being less useful in actual work. In order to express the composition of a rook, or, more precisely, of a magma, a simple notation has been devised, which makes use of numerals to indicate the several subdivisions. Thus the symbol II. 5. 2.3 indicates that the magma which it represents belongs in Class II, dosalane; order 5, perfelio; rang 2, domalkalic; and subrang 3, sodipotassic. 1 That such a system is convenient we can see at a glance; but its limitations, due to the distinction between normative and actual minerals, must never be overlooked. Analyses are readily classified and summarized by the system; as regards minerals it is confessedly incomplete. The important alferric minerals muscovite, biotite, augite, and hornblende fall outside of the classification, and have to be expressed by means of a recalculation from a norm into a mode. It is an artificial classification of great provisional value; but its ultimate standing is yet to be determined by the severe tests of experience. Even if it should be finally adopted by all petrologists, some form of classification like that now in vogue would have to be retained with it. Good analyses can not be obtained for every rock which the geologist is called upon to determine, and in many cases he must be content with the results of a microscopic examination. He can then say at once that a certain rock consists of alkali feldspar, quartz, and subordinate femic minerals, and so define it as a granite or rhyolite. To accurately name its subrang is a more troublesome matter, and impracticable without analytical data. 2 In short, the quantitative system can only be applied to the classification of rocks which have been quantitatively studied, but then it yields results of unquestionable utility. It brings to light magmatic analogies which 1 For the detailed development of this notation, which can be extended to grads and subgrads, see H. S. Washington, Prof. Paper U. S. Geol. Survey No. 28, 1904, pp. 13-15. On the calculation of norms, see G. I. Finlay, Jour. Geology, vol. 18, 1910, p. 58. 2 The need of rock names for field use is fully recognized by the authors of the quantitative system. IGNEOUS ROCKS. 433 might not be recognized without its aid, and so assists in the com- parison of magmas and in the study of their differentiation. From the application of the classification to the study of rocks, one highly beneficent result has already followed. The two memoirs of H. S. Washington, 1 in which he has collected and classified all the trust- worthy rock analyses which had been recorded between 1869 and 1900, are of the highest value and go far to justify the system. COMPOSITION OF ROCKS. Now, passing on from the general statements relative to classifica- tions, we may consider the actual composition of rocks as revealed by chemical analysis. In order to do this most advantageously, and to compare classifications, the ordinary miner alogical grouping will be followed, but the rocks within each group will be arranged in the order of the quantitative system, and the brief description of each one will precede the analyses. To the descriptions the magmatic symbols and magmatic names are appended, and after each table the compo- sition of the norms , as found in Washington’s tables, will be given. We shall thus be able to see how nearly the two classifications coin- cide, and so be better fitted to judge of their comparative merits. As a rule, the analyses are those which have been made in the laboratory of the United States Geological Survey, and are cited from the col- lection published in Bulletin No. 591. Only those are selected which have been characterized by Washington as excellent. In a few cases analyses from other sources must be used, but due credit will be given. Since rocks are aggregates of minerals, all sorts of interme- diate variations are possible, but in a work of this general character such minor details of classification must be ignored. Only the larger features of the subject can be taken into account. THE RHYOLITE -GRANITE GROUP. In Class I of the quantitative classification, order 1, perquaric, is represented by rocks which consist mainly of quartz, such as quartz veins and segregations of igneous origin. In order 2, doquaric, Wash- ington places a few rocks which contain from 53 to 69 per cent of quartz, but none of them is particularly important. It is in order 3, quarfelic, that the noteworthy rocks begin to appear, and a large number of them belong in the familiar group of rhyolites and gran- ites. With this group it is convenient to begin. 1 Prof. Papers U. S. Geol. Survey Nos. 14 and 28. For analyses made in the laboratories of the Survey, see also Bull. No. 591. For an extended application of the quantitative classification, see Washington’s Roman comagmatic region, Pub. No. 51 of the Carnegie Institution, 1906. For reviews and criticisms of the new system, see A. Michel-L6vy, Bull. Carte g6ol. France, No. 92, 1903; A. H[arker], Geol. Mag., 1903, p. 173; J. W. Evans, Science Progress, vol. 1, 1906, p. 259; E. B. Mathews, Am. Geologist, vol. 31, 1903, p. 399; L. Milch, Centralbl. Min., Geol. u. Pal., 1903, p. 677; and G. W. Tyrrell, Sci. Progress, vol. 9, p. 61, 1914. 97270°— Bull. 616—16 28 434 THE DATA OF GEOCHEMISTRY. In the broadest sense, granite may be defined as a holocrystalline, plutonic rock, consisting chiefly of quartz and an alkali feldspar, the latter being commonly orthoclase or microcline. A soda granite is one containing a soda feldspar, preferably anorthoclase. With these dominant minerals there may be, and usually are, subordinate species, such as muscovite, biotite, hornblende, etc. Hence the varieties muscovite granite, biotite granite or granitite, hornblende granite, tourmaline granite, and the like. When only quartz and feldspar are present the rock is called aplite, although it must be observed that this term is often used in other senses . 1 Rhyolite is the eruptive equivalent of granite and has the same chemical composition. The minerals which develop individually in it are also broadly the same, quartz and alkali feldspar largely predominating. Rhyolite, how- ever, very commonly contains more or less undifferentiated glass, and obsidian is a wholly vitreous variety. The quartz porphyries, which are intermediate between granites and rhyolites, are old, devitrified forms of the latter. Nevadite, liparite, and quartz trachyte are synonyms for rhyolite. The differences between granite and rhyolite are structural and genetic; chemically and magmatically they are the same. This essential identity of composition appears in the subjoined tables of analyses. First in order come the rhyolites. 1 On account of this ambiguity in the use of the word aplite, J. E. Spurr has proposed the name “alaskite” for rocks of this character. For the corresponding eruptive or fine-grained porphyritic rocks tho term “tordrillite” is offered. Am. Geologist, vol. 25, 1900, p. 229. On the formation of granite see H. Le Chate- lier, Annales des mines, 8th ser., vol. 13, 1888, p. 232. On the origin of pegmatite see J. B. Hastings, Trans* Am. Inst. Min. Eng., vol. 39, 1909, p. 104; E. S. Bastin, Jour. Geology, vol. 18, 1910, p. 297; and A. Harker, Natural history of igneous rocks, p. 293. On the origin of granite see A.. Brun, Eclog. Geol. Helvet., vol. 12, 1912, p. 172. IGNEOUS ROCKS. 435 Analyses of rhyolites. A. From Buena Vista Peak, Amador County, California. Analysis by W. F. Hillebrand. Described by H. W. Turner as containing sanidine, quartz, and biotite in a glassy groundmass. Magmatic symbol, 1.3.1.2. Magdeburgose. B. From near Willow Lake, Plumas County, California. Analysis by Hillebrand. Described by J. S. Diller as containing phenocrysts of quartz and feldspar, in a groundmass of the same materials. Symbol, 1.3.1.3. Alaskose. C. Obsidian, Obsidian Cliff, Yellowstone National Park. Analysis by J. E. Whitfield. Described by Arnold Hague and J. P. Iddings. A glass containing microlites of augite and ferric oxide, with traces of quartz and feldspar. Symbol, 1.3.1. 3. Alashose. D. From Madison Plateau, Yellowstone National Park. Analysis by Whitfield. Not described. Sym- bol, 1.3.1. 4. E . From the Hyde Park dike, Butte distr ict, Montana. Analysis by H. N. Stokes. Contains, according to W. H. W eed, sanidine, quartz, plagioclase, and biotite, in a groundmass of quartz and feldspar. Symbol, 1.3.2.3. Tehamose. F. From “Elephant’s Back,” Yellowstone National Park. Analysis by Whitfield. Reported by J. P. Iddings to contain quartz and sanidine, with a little augite and magnetite, in a glassy groundmass. Symbol 1.3.2.3. Tehamose. G. From Haystack Mountain, Aroostook County, Maine. Analysis by Hillebrand. Described by H. E . Gregory. Contains quartz, albite, and orthoclase, with titanite and accessory chlorite and kaolin. Symbol 1.4.1.3. Liparose. H. From Crater Lake, Oregon. Analysis by Stokes. Described by H. B. Patton. Contains plagioclase, hornblende, hypersthene, and magnetite, in a glassy groundmass crowded with microlites of feldspar and augite. Symbol, 1. 4.2.4. Lassenose. A B c D E F G H Si0 2 73. 23 74. 24 75. 52 75. 19 74. 34 75. 34 75. 98 71. 87 ai 2 o 3 12. 73 14. 50 14. 11 13. 77 12. 97 12. 51 12. 34 14. 53 Fe 2 0 3 .99 1. 27 1. 74 .61 .75 .42 .85 1. 28 FeO .16 . 67 .08 1. 37 .54 1. 55 .93 1. 02 MgO .22 .25 . 10 .09 .86 .32 .15 .48 CaO .61 .11 .78 . 68 .85 1. 07 .13 1. 59 Na 2 0 1. 91 3. 00 3. 92 3. 83 2. 49 3. 31 4. 02 5. 08 K 2 0 5. 17 3. 66 3. 63 3. 33 4. 72 4. 17 4. 44 2. 84 H 2 0- . 53 'l 1 OK 1. 03 'l . 24 . 06 h 2 o+ 4. 51 2. 04 ^ . 39 1. 11 > . 86 .64 .22 Ti0 2 .09 .20 None. None. . 18 None. .17 .41 Zr0 2 . 05 .03 . 04 P 2 0 5 .02 . 07 None. . 07 None. . 03 . 10 MnO Trace. .06 None. Trace. Trace. . 07 Trace? BaO . 02 . 18 . 07 . 07 . 08 SrO None. Trace. Trace. Trace? . 03 Li 2 0 Trace. None. .02 Trace. Trace. Trace. SO, .03 . 29 . 03 . 42 FeS 2 . 11 None. Cl Trace. 100. 19 100. 28 100. 38 99. 83 100. 06 100. 04 100. 02 99. 63 Norms. A B c D E F G H Q 40. 7 42.0 36.7 38.2 38. 7 36.1 35.1 27.4 or 31.1 21. 7 21.7 19.5 27.8 25.0 26.1 16.7 ab 15. 7 25.2 33.0 32.0 21.0 27.8 33.5 43.0 an 2.8 .6 3.9 3.3 4.2 5.6 .6 8.1 C 3. 0 5. 4 2. 2 2. 8 2. 2 4 . 8 Fy . 6 .6 .3 2.2 2.4 3.3 1.4 1.2 mt .5 1.9 .2 .9 1.2 .7 1.2 1.4 hm 1. 1 1. 6 il .8 436 THE DATA OP GEOCHEMISTRY. The following analyses represent quartz porphyry: Analyses of quartz porphyry. A. From near Blowing Rock, Watauga County, North Carolina. Analysis by W. F. Hillebrand. Re- ported by A. Keith to contain quartz and orthoclase, with subordinate sericite, chlorite, and biotite. Mag- matic symbol, I.3.I.2. Magdeburgose. B. From the Modoc mine, Butte district, Montana. Analysis by Hillebrand. Contains, according to W. H. Weed, quartz, orthoclase, and plagioclase in a groundmass of quartz and feldspar. Symbol, I.4.2.3. Toscanose. C. From Prospect Mountain, Leadville district, Colorado. Analysis by L. G. Eakins. Described by W. Cross. Contains orthoclase, plagioclase, quartz, biotite, apatite, magnetite, and zircon. Symbol, I.4.2.3. Toscanose. D. From the Swansea mine, Tintic district, Utah. Analysis by H. N. Stokes. Described by G. W. Tower and G. O. Smith. Contains feldspar, quartz, magnetite, apatite, secondary pyrite, and a little chlorite and biotite. Symbol, I.4.2.3. Toscanose. E. From Grizzly Mountains, Plumas County, California. Analysis by Hillebrand. Contains, accord- ing to H. W. Turner, quartz, feldspar, and pyrite, in a fine groundmass. Symbol, I.4.2.3. Toscanose. A B c D E Si0 2 79. 75 69. 95 73. 50 71. 56 73. 25 ai 2 o 3 10. 47 15. 14 14. 87 14. 27 13. 25 Fet,Og . 64 .38 . 95 1 .89 FeO . 92 . 83 .42 1. 74 MgO . 13 . 56 .29 . 42 .28 CaO . 15 1. 45 2. 14 1. 18 2. 23 Na 2 0 1. 36 2. 70 3. 46 3. 00 2. 69 k 2 o 6. 01 6. 36 3. 56 } .90 J 4. 37 3. 79 h 2 o- . 08 . 40 . 36 .07 h 2 o+ . 60 . 91 . 79 1. 03 Ti0 2 . 15 .24 .38 Trace. Zr0 2 .05 . 02 co 2 . 37 None. 1. 05 P 2 0 5 Trace. . 10 None. . 13 Trace. MnO Trace. .08 .03 Trace. Trace. BaO . 06 . 13 . 28 Trace. SrO Trace. . 02 Trace. Trace. Trace? Li 2 0 Trace. Trace. None. Trace. Cr 2 0 3 Trace. VoO,-.. . 01 ci..! .06 Cu . 03 FcS .39 2. 29 .58 ~ ^ 100. 37 100. 06 100. 12 99. 99 99. 96 Norms. A B c D E Q 47. 8 25. 5 34. 7 34. 2 30. 1 or 35. 6 37. 8 21. 1 26. 1 33. 9 ab 11. 5 22. 5 29. 3 25. 2 22. 5 an . 8 7. 2 10. 6 5. 8 7. 2 C 1. 4 1.1 1.4 2.5 di 3. 2 hy 1. 4 2. 7 . 7 1. 1 2.3 mt .8 1. 1 1.4 . 9 il . 5 pr 2.3 .6 IGNEOUS ROCKS. 437 The subjoined analyses of granites are all by W. F. Hillebrand : 1 Analyses of granites. A. From Currant Creek Canyon, near Pikes Peak, Colorado. Described by E. B. Mathews. Contains microcline, quartz, muscovite, and sericitic aggregates replacing plagioclase and a part of the microcline. Magmatic symbol, I.3.I.2. Magdeburgose. B. Biotite granite, Sentinel Point, Pikes Peak, Colorado. Described by Mathews. Contains micro- cline, microcline-perthite, quartz, biotite, a little oligoclase, and accessory fluorite, apatite, zircon, sphene, allanite, and magnetite. Symbol, I.3.I.3. Alaskose. C. From Currant Creek Canyon, Pikes Peak, Colorado. Described by Mathews. Contains perthitic microcline, quartz, biotite, muscovite, altered plagioclase, and flakes of limonite. Symbol, I.4.I.2. Omeose. D. Biotite granite, Mount Ascutney, Vermont. Described by R. S. Daly. Contains quartz, orthoclase, plagioclase, biotite, magnetite, sphene, apatite, and zircon. Symbol, I.4.I.3. Liparose. E. Soda granite, Pigeon Point, Minnesota. Described by W. S. Bayley. Contains feldspar, quartz, chlorite, some muscovite, rutile, leucoxene, hematite, and apatite, and sometimes secondary calcite. Symbol, I.4.I.3. Liparose. F. Granitite, near Florissant, Colorado. Described by Mathews. Contains microcline, albite, quartz, and biotite. Symbol, 1.4. 1.4. Kallerudose. G. Granite, Big Timber Creek, Crazy Mountains, Montana. Reported by J. E. Wolff as containing quartz, orthoclase, oligoclase, and biotite. Symbol, I.4.2.3. Toscanose. H. Aplite, Yuba Gap, Sierra County, California. Described by H. W. Turner. Contains orthoclase, quartz, plagioclase, a little microcline, brown mica, and iron ore. Symbol, I.4.2.3. Toscanose. A B C D E F G H Si0 2 74. 40 77. 03 73. 90 71. 90 72. 42 75. 92 74. 37 76. 03 A1 2 0 3 14. 43 12. 00 13. 65 14. 12 13. 04 12. 96 13. 12 13. 39 Fe 2 0 3 .89 .76 .28 1. 20 .68 .33 .73 .48 FeO.. .22 .86 .42 .86 2. 49 1. 40 .87 .31 MgO .07 .04 .14 .33 .58 Trace. .35 .05 CaO .58 .80 .23 1. 13 .66 .15 1. 26 1. 28 Na 2 0 1. 76 3. 21 2. 53 4. 52 3. 44 4.60 2. 57 2. 98 K 2 0 6. 56 4. 92 7. 99 4. 81 4. 97 4. 15 6. 09 5. 18 h 2 0- .15 .14 .16 .18 l 1 91 .16 .05 .15 h 2 o+ .92 .30 .33 .42 > 1. Z± .32 .25 .34 Ti0 2 .12 .13 .07 .35 .40 .05 .29 .07 Zr0 2 .04 co 2 .21 . 03 p 2 o 5 .22 Trace. .05 .11 .20 Trace. .06 .03 MnO Trace. Trace. Trace. .05 .09 .04 Trace. Trace. BaO Trace. Trace. Trace. .04 .15 Trace. .10 .04 SrO None. None. None. Trace? None. Trace. Trace. Li 2 0 Trace. Trace. Trace. Trace? Trace. Trace. None. F .04 . 36 None. .06 . 12 Cl . 02 Trace. FeS 2 Trace. 100. 36 100. 55 99. 75 100. 35 100. 33 100. 23 100. 11 100. 33 Norms. J A. Gautier (Compt. Rend., vol. 32, 1901, p. 932) found traces of nitrogen, argon, arsenic, and iodine in granite. 438 THE DATA OF GEOCHEMISTRY. All of the rocks here cited belong in the first subclass of Class I and lie between the limits indicated by the symbols 1. 3. 1.2 and I. 4. 2. 4. Some granites appear in Washington’s tables under Class II, but they are few in number and represent, probably, intermediate gradations toward the syenites. So far as the foregoing analyses are concerned, they show that up to this point the quantitative and miner alogical classification coincide fairly well and that the norms can not vary very much from the modes. The normative corundum 1 probably represents the micas, either muscovite or biotite, or both, so that the actual orthoclase of these rocks must be lower than is shown in the norms. The latter show with sufficient emphasis that quartz and alkali feldspars are the most important minerals in the granite- rhyolite group and that the rocks differ chiefly in the varying pro- portions of quartz, orthoclase or microcline, and albite or anorthoclase. The presence of much muscovite in a granite, however, would increase the divergence between norm and mode, and even throw the rock into some other order than those shown by the limiting symbols just given. THE TRACHYTE-SYENITE GROUP. The trachyte-syenite series of rocks differs from the rhyolite-granite series in being free, or nearly so, from quartz. The trachytes, like the rhyolites, are eruptive rocks; the syenites resemble granite in their plutonic origin. Between trachyte and syenite there are intermediate forms, analogous to the quartz porphyries. All of these rocks contain principally alkali feldspars, with subordinate femic minerals, and often alferric species such as hornblende or mica. These minor con- stituents are recognized in nomenclature by such terms as biotite trachyte, mica syenite, hornblende syenite, etc. There are also many varietal names, which are based on minor distinctions. The nephe- line syenites will be considered separately. The following analyses represent typical examples within the series as defined here : i Or undistributed alumina. IGNEOUS ROCKS. 439 Analyses of trachyte-syenite rocks. A. Nordmarkite, Mount Ascutney, Vermont. Analysis by W. F. Hillebrand; description by R. S. Daly. Contains orthoclase, plagioclase, quartz, hornblende, magnetite, apatite, and zircon, with very little biotite, titanite, diopside, and allanite. Magmatic symbol, I.5.I.3. Phlegrose. B. Quartz syenite porphyry, Gray Butte, Bearpaw Mountains, Montana. Analysis by H. N. Stokes. Described by W. H. Weed and L. V. Pirsson. Contains anorthoclase, microlites of plagioclase, aegirite, augite, quartz, and apatite, with an occasional zircon and traces of biotite. Symbol, I.5.I.4. Nordmarkose. C. Biotite trachyte. Dike Mountain, Yellowstone National Park. Analysis by Hillebrand. Reported by Arnold Hague and T. A. Jaggar as containing plagioclase, orthoclase, biotite, magnetite, and chlorite. Symbol, I.5.I.4. Nordmarkose. D. Soda syenite porphyry, Moccasin Creek, Tuolumne County, California. Analysis by Stokes. Described by H. W. Turner. Consists mainly of albite, with possibly segirite. Symbol, I.5.I.5. Tuo- lumnose. E. Soda syenite, Douglas Island, Alaska. Analysis by Hillebrand. Described by G. F. Becker. Con- tains mostly albite, with secondary quartz, calcite, and pyrite. Symbol, I.5.I.5. Tuolumnose. F. Biotite trachyte, Dike Mountain, Yellowstone National Park. Analysis by Hillebrand. Reported by Hague and Jaggar to contain orthoclase, plagioclase, biotite, and chlorite. Symbol, I.5.2.3. Pulaskose. A B C D E F Si0 2 65. 43 66. 22 63. 24 67. 53 63. 01 57. 73 A1 2 0 3 16. 11 16. 22 17. 98 18. 57 18. 47 18. 93 Fe 2 0 3 1. 15 1. 98 2. 67 1. 13 .06 1. 97 FeO 2. 85 .16 .85 .08 .32 1. 92 MgO .40 .77 .63 .24 .06 .91 CaO 1. 49 1. 32 .93 .55 2. 66 2. 78 Na 2 0 5. 00 6. 49 6. 27 11. 50 10. 01 5. 52 K 2 0 5. 97 5. 76 5. 47 .10 .39 6. 11 H 2 0- .19 .08 .37 .15 .05 .22 h 2 o+ .39 .24 .80 .31 .27 2. 93 Ti0 2 .50 .22 .38 .07 .13 .33 Zr0 2 . 11 Trace. Trace. C0 2 None. 2. 01 . 26 PA . 13 .10 .22 . 11 .06 .25 so 3 .02 Trace. Cl . 05 . 04 F .08 Trace. Trace. MnO .23 Trace. .04 Trace. .06 .06 BaO . 03 . 29 . 25 .02 . 16 SrO .06 . 03 Trace. Trace. . 09 V 2 0 3 . 01 . 01 . 01 Li 2 0 Trace. Trace. None. Trace. FeSo .07 Trace. 2. 10 . 02 100. 18 99. 97 100. 14 100. 34 99. 69 100. 20 440 THE DATA OF GEOCHEMISTRY. Analyses of trachyte-syenite rocks — Continued. G. Augite syenite porphyry, Copper Creek basin, Yellowstone National Park. Analysis by Hillebrand. Contains, according to Hague and Jaggar, augite, biotite, orthoclase, a little hornblende, and quartz. Sym- bol, I.5.2.4. Laurvikose. H. Augite syenite. Turnback Creek, Tuolumne County, California. Analysis by Stokes. Reported by Turner to contain orthoclase and augite, with less plagioclase and quartz. Symbol, H.5.1.2. Highwoodose. I. Syenite, Yogo Peak, Little Belt Mountains, Montana. Analysis by Hillebrand. Described by Weed and Pirsson. Contains orthoclase, oligoclase, quartz, apatite, titanite, iron ores, pyroxene, hornblende and biotite, with traces of decomposition products. Symbol, II.5.2.3. Monzonose. J. Syenite, La Plata Mountains, Colorado. Analysis by Stokes. Reported by W. Cross to contain much alkalifeldspar, some oligoclase, augite, biotite, and hornblende, with a little titanite, magnetite, and apatite. Symbol, II.5.2.3. Monzonose. K. Syenite, Crazy Mountains, Montana. Analysis by Hillebrand. Reported by J. E. Wolff to contain anorthoclase, hornblende, augite, sphene, apatite, and magnetite. Symbol, II.5.2.4. Aherose. G H I J K Si0 9 64. 40 61. 28 61. 65 59. 79 58. 28 ALO- 16. 90 14. 71 15. 07 17. 25 17. 89 Fe 2 0 3 1. 86 1. 21 2. 03 3. 60 3. 20 FeO " 1. 37 2. 85 2. 25 1. 59 1. 73 MgO 1. 13 1. 69 3. 67 1. 24 1. 51 CaO 2. 60 5. 61 4. 61 3. 77 3. 69 Na.,0 5. 79 2. 99 4. 35 5. 04 5. 89 KoO 4. 56 7. 70 4. 50 5. 05 5. 34 H 2 0 — . 16 .28 .26 . 19 . 17 h 2 o+ . 39 .43 .41 . 39 . 98 Ti0 2 . . 23 .41 .56 .67 .64 Zr0 2 . 02 co 2 None. . 72 p 2 0 5 .21 .16 .33 .35 .26 so, .08 .04 Cl F MnO .07 Trace. .09 .20 .06 BaO . 27 . 72 .27 . 14 .36 SrO . 14 .04 . 10 . 11 .05 T/LO Trace. Trace. Trace. Trace. 100. 10 100. 16 100. 15 100. 14 100.05 Norms. A B c D E F Q 8. 8 5. 3 2. 8 or 35. 6 33. 9 32. 8 0. 6 2. 2 36. 1 ab 42.4 51.9 52. 9 95.4 83.3 37.7 an 3.6 4.4 4.4 8.6 ne . 6 4.8 ac 2. 8 1.4 di 3.4 1.4 1. 3 L 2 4.5 wo 1.6 .5 3.1 hv 2.4 1.6 of. 1.0 mt 2.1 1.6 .2 3.0 hm 1. 0 1. 6 . 5 il . 9 .3 .8 .3 .6 2.1 IGNEOUS ROCKS. 441 Analyses of trachyte-syenite roclcs — Continued. G H I J K Q 7. 1 3.4 6. 2 3. 1 or 27. 2 45. 6 26. 7 30. 6 31. 7 ab 48. 7 25. 2 36. 7 42. 4 41. 9 an 6. 7 3.9 8.3 9.5 6.4 ne 4.3 ac di 5.2 16. 0 11.9 6.7 8.0 wo 1.9 hv .8 5.0 oL mt 2.8 1.6 3.3 3. 2 4.6 hm 1. 4 il 5 .8 1. 1 1. 2 1. 2 ap .8 . 7 The rocks of this group, being deficient in quartz, tend to run lower in silica than the granites and rhyolites. Their magmatic range is between 1. 5. 1.3 and II. 5. 2.4; so that, despite their miner- alogical similarities, they are divided between two classes, but fall within each class into the same order, the perfelic. With decrease of quartz, at one end of the series, they shade into rocks in which the femic minerals are no longer subordinate. Among these femic rocks are found varieties which have been named minette, kersantite, lamprophyre, and shonkinite. Some of these terms are vaguely used, and are very often applied to rocks of a transitional character which contain considerable amounts of soda-lime feldspars. The subjoined analyses represent some of these femic syenites. 442 THE DATA OF GEOCHEMISTRY. Analyses offemic syenites. A. Soda minette, Brathagen, Laugendal, Norway. Analysis by V. Schmelck. Described by W. C. Brogger (Die Eruptivgesteine des Kristianiagebietes, vol. 3, 1898, p. 130). Contains, in approximate percentages, 54 soda feldspar, 29 lepidomelane, 13 aegirine-augite, 2\ apatite, and 1 sphene. Magmatic symbol, II.5.2.4. Akerose. B. Soda minette, Hao, Langesund Fjord, Norway. Analysis by Schmelck, description by Brogger (Die Eruptivgesteine des Kristianiagebietes, vol. 3, 1898, p. 139). Contains about 51§ per cent soda feld- spar, 26.5 lepidomelane, 16| diopside, 2\ each of apatite and sphene. Symbol, II.6.1.4. Laurdalose. C. Syenitic lamprophyre, Two Buttes, Prowers County, Colorado. Analysis by W. F. Hillebrand. Contains, according to W. Cross, alkali feldspar, diopside, biotite, magnetite, and olivine. Symbol, III.5.2.2. Prowersose. D. Shonkinite, Beaver Creek, Bearpaw Mountains, Montana. Analysis by H. N. Stokes. Described by W. H. Weed and L. V. Pirsson. Contains anorthoclase, diopside, biotite, iron ores, and apatite, with a very little olivine and nephelite. Symbol, HI.5.1.3. E. Shonkinite, Yogo Peak, Little Belt Mountains, Montana. Analysis by Hillebrand. Described by Weed and Pirsson. Contains augite and orthoclase, with biotite, iron ore, andesine, apatite, olivine, and a trace of kaolin. Symbol, III.6.2.3. Shonkinose. A B C D E Si0 2 51. 22 51. 95 50. 41 50. 00 48. 98 12. 29 2. 88 A1 2 0 3 17. 56 14. 95 12. 27 9. 87 FeXC 3. 51 4. 09 5. 71 3. 46 FeO 4. 34 5. 70 3. 06 5. 01 5. 77 MgO 3. 22 3. 54 8. 69 11. 92 9. 19 CaO 4. 52 6. 10 5. 43 7. 08 8. 31 9. 65 Na 2 0 5. 72 . 97 2. 41 2. 22 K 2 0 4. 37 4. 45 7. 53 5. 02 4. 96 h 2 o- H 2 0+ 1} 1.93 } 1.10 .46 1. 80 .17 1. 16 .26 .56 Ti0 2 1. 70 1. 95 1. 47 . 73 1.44 co 2 .60 .31 PoO- 1. 08 1. 15 . 46 .81 co 00 A 2 v - / 5* so, None. .02 Cl Trace. .08 F Trace? .16 .22 v,o, .03 Cr 2 0 3 . 11 Trace. MnO .20 .30 . 15 Trace. .08 NiO . 04 . 07 BaO . 23 .32 .43 SrO .06 . 07 .08 Li 2 0 Trace. Trace. Trace. 99. 97 100. 71 100. 42 100. 01 99. 99 Norms. 1 A B C D E or 25. 6 26. 1 44.5 29.5 29.5 ab 32. 0 28.3 4.2 8.9 5.3 an 9. 5 3. 3 6. 7 1. 1 8.6 ne 8.8 9. 7 2.3 6.2 6.8 di 5.3 16.8 20.4 28.9 26.5 ol 5.6 3.2 8.6 14.8 11.7 mt 5. 1 6.0 5.8 5.1 4.2 il 3.2 3. 7 2.8 1.4 2.6 an 2.5 2. 7 1.0 1.7 2.2 hm 1.6 IGNEOUS ROCKS. 443 A comparison of the norms under A and B with the modes as given by Brogger will show how widely the two diverge. These two rocks are in Class II; the others, on account of their higher propor- tion of femic minerals, fall in Class III. All five of the rocks contain micas, which accounts for some of the differences between the mag- matic and the mineralogical composition. In A and B, also, sphene is reported, while in the norms the titanium is reckoned entirely as ilmenite. NEPHELITE ROCKS. In the norms of the foregoing rocks small quantities of nephelite appear. These mark a transition from the syenites and trachytes proper to the phonolites and nepheline syenites, in which the lenad minerals replace the alkali feldspars to a greater or less extent. Taking the nephelite rocks first in order, we find an eruptive and a deep-seated group, just as with the trachyte-syenite series. Quartz is excluded from these rocks, for if it were introduced in excess into the magma it would convert the lenads into feldspars, nephelite into albite, and leucite into orthoclase. In phonolite we have commonly orthoclase, nephelite, and pyroxene; tinguaite is a varietal name. Some rocks richer in femic minerals than the phonolites have been classed with the basaltic basanites, but they contain so little soda- lime feldspar that it is well to include them in the following table, as allied to phonolite chemically. The subjoined data relate to members of the eruptive series. 444 THE DATA OF GEOCHEMISTRY. v Analyses of eruptive nephelite rocks. A. Phonolite, Southboro, Massachusetts. Analysis by H. N. Stokes. Collected by B. K. Emerson but not described. Magmatic symbol, 1.6. 1.4. Miaskose. B. Phonolite, Black Hills, South Dakota. Analysis by W. F. Hillebrand. Described by W. Cross. Contains orthoclase, nephelite, aegirite, noselite, sodalite, sphene, apatite, and zircon; also secondary zeolites and calcite, but no magnetite. Symbol, 1.6. 1.4. Miaskose. C. Phonolite, Cripple Creek, Colorado. Analysis by Hillebrand. Described by Cross. Contains ortho- clase, nephelite, sodalite, noselite, aegirite, etc. Symbol, 1.6. 1.4. Miaskose. D. Phonolite, Pleasant Valley, Colfax County, New Mexico. Analysis by Hillebrand. Reported by Cross to contain nephelite, alkali feldspar, aegirite, traces of magnetite, and a little noselite or sodalite. Symbol, I.6.I.4. Miaskose. E. Tinguaite, Bear Creek, Bearpaw Mountains, Montana. Analysis by Stokes. Described by W. H. Weed and L. V. Pirsson. Contains orthoclase, nephelite, cancrinite, augite, aegirite, apatite, a little soda- lite, and a doubtful hornblende. Symbol, H.6.1.3. Judithose. F. Phonolite, Uvalde County, Texas. Analysis by Hillebrand. Reported by Cross to contain orthoclase, nephelite, and aegirite, with a very little hornblende, augite, and magnetite. Symbol, II.6.1.4. Laurdalose. G. Basanite, near Big Mountain, Uvalde County, Texas. Analysis by Hillebrand; description by Cross. Contains alkali feldspar, augite, magnetite, olivine, nephelite, aegirite, biotite, and zeolitic minerals. Symbol, H.6.2.4. Essexose. H. Basanite, Mount Inge, Uvalde County, Texas. Analysis by Hillebrand; description by Cross. Contains orthoclase, nephelite, hornblende, augite, aegirine-augite, olivine, magnetite, apatite, and a trace of pyrite. Symbol, H.7.1.4. Lujavrose. A B C D E F G H Si0 2 54. 22 57. 86 58. 98 56. 24 57.46 54. 42 48. 23 48. 13 A1 2 0 3 20. 20 20. 26 20. 54 21. 43 15. 40 20. 76 17. 43 18.44 Fe 2 0 3 2. 35 2. 35 1. 65 2. 01 4. 87 2.64 2. 77 3. 41 FeO 1. 02 .39 .48 . 55 .87 1. 33 5. 92 4. 30 MgO .29 .04 .11 .15 1. 37 .22 2. 99 3. 06 CaO .70 .89 .67 1. 38 2. 59 1.34 6. 38 5. 89 Na 2 0 9.44 9. 47 9. 95 10. 53 5. 48 10.41 6. 87 8.00 K 2 0 4.85 5.19 5. 31 5. 74 9.44 4.89 2. 78 3. 80 H 2 0- .42 .21 .19 . 12 .09 .22 . 54 .18 H 2 0+ — 5.57 2. 40 .97 .86 .82 2. 50 2.84 1. 59 Ti0 2 .38 .22 .24 .26 .60 .40 2.00 1. 74 ZrOo . 15 .20 .09 . 15 .04 .05 CO,. . 13 p 2 o 5 . 11 .03 .04 .06 .21 .11 .69 .49 so 3 ! None. .06 .20 . 10 . 13 s .03 .03 .01 .08 .09 Cl 1 .08 .28 . 12 .20 .23 .03 .29 F 1 (?) Trace. Trace. None. .06 v 9 o, .04 MnO .19 .21 .26 .08 Trace. .15 .18 .19 NiO None. None. Trace. . 02 BaO Trace. .09 None. .08 .60 .04 .08 .10 SrO .04 None. .03 . 16 Trace. .08 .10 Li 2 0 Trace. Trace. Trace. Trace. Trace. Trace. Trace. 99. 74 99. 97 100. 07 99. 86 100. 42 99. 82 99. 97 99. 93 Norms. A B C D E F G H or 28.9 30.6 31.1 33.9 55.6 29.5 16.7 22.2 ab 33.5 39.3 38.3 22.0 5.8 23.6 23.6 14. 1 an 8.3 3. 1 ne 23.3 19.0 17.2 32.7 9.9 30.4 18.7 29.0 so 3. 9 2. 9 ac 2. 8 4. 2 4. 6 .6 13. 8 7.4 di 1 . 5 2.6 2.9 8.0 4.9 15.9 18.6 ol 3.7 .8 WO 1. 9 1.5 1.0 .6 mt . o o 1 1.2 3.9 4.9 il . Z. 1 Q 1.2 .8 3.7 3.4 ap . o 1.7 1.1 IGNEOUS ROCKS. 445 The following table contains analyses of deep-seated rocks of the nephelite series : Analyses of deep-seated nephelite rocks. A. Elseolite syenite, or litchfieldite, Litchfield, Maine. Analysis by L. G. Eakins. Described by W. S. Bayley. Contains elseolite, two feldspars, and lepidomelane, with accessory sodalite, cancrinite, and zircon. Magmatic symbol, 1.5. 1.4. Nordmarkose. B. Elseolite syenite, Beemersville, New Jersey. Analysis by Eakins. Described by J. P. Iddings. Contains nephelite, orthoclase, segirite, and biotite, with less melanite, titanite, apatite, magnetite, and zircon. Symbol, 1.5. 6.3. Beemerose. C. Nephelite syenite, Brookville, New Jersey. Analysis by G. Steiger. Described by F. L. Ransome. Contains alkali feldspars, altered nephelite, amphibole, biotite, cancrinite, plagioclase, muscovite, segirine- augite, apatite, fluorite, and traces of magnetite, with secondary analcite, sericite, and natrolite ( ?). Symbol, I.6.2.4. Viezzenose. D. Elseolite syenite. Red Hill, Moultonboro, New Hampshire. Analysis by W. F. Hillebrand; descrip- tion by Bayley. Contains elseolite, hornblende, augite, biotite, sodalite, albite, and orthoclase, with accessory apatite, sphene, magnetite, and an occasional zircon. Symbol, II.5.1.4. Umptekose. E. Nephelite syenite, Cripple Creek, Colorado. Analysis by Hillebrand. Described by W. Cross. Contains alkali feldspars, nephelite, sodalite, augite, some segirine, hornblende, biotite, sphene, apatite, and magnetite. Symbol, II.5.2.4. Akerose. F. Urtite, Kola Peninsula, Finland. Analysis by N. Sahlbom. Described by W. Ramsay, Geol. Foren. Forhandl., vol. 18, p. 463, 1896. Contains, in percentages, nephelite, 85.7; pyroxene, mostly segirite, 12.0; and apatite, 2.0. Symbol, II.9.1.4. Urtose. G. Ijolite, Iivaara, Finland. Analysis by A. Zilliacus. Described by W. Hackman, Bull. Comm. geol. Finland, No. 11. 1900. Contains, in average percentages, nephelite, 51.6; pyroxene, 39.2; apatite, 4.3; titanite, 2.1; and ivaarite, 0.7. Symbol, II.9. 1.4. Urtose. H. Theralite, Crazy Mountains, Montana. Analysis by Hillebrand. Contains, according to J.E. Wolff, augite, segirite, biotite, sodalite, nephelite, feldspar, apatite, magnetite, and titanite. Symbol, III.7.1.4. Malignose. A B c D E F G H Si0 2 60. 39 53. 56 54. 68 59. 01 54. 34 45. 28 43. 02 44. 65 A1 2 0 3 22. 57 24. 43 21. 63 18. 18 19. 21 27. 37 24. 63 13. 87 Fe 2 0 3 .42 2. 19 2. 22 1. 63 3. 19 3. 53 3. 59 6. 06 FeO 2. 26 1. 22 2.00 3. 65 2. 11 .49 2. 17 2. 94 MgO .13 .31 1. 25 1. 05 1. 28 .33 1. 96 5.15 CaO .32 1.24 2. 86 2. 40 4. 53 1. 22 5. 47 9. 57 Na 2 0 8. 44 6. 48 7. 03 7. 03 6. 38 17. 29 14. 81 5. 67 K 2 0 4. 77 9. 50 4. 58 5. 34 5. 14 3. 51 2. 99 4. 49 h 2 o - } .57 } .93 . 27 . 15 . 14 } .40 ) . 96 h 2 o+ 1. 88 . 50 1. 17 2. 10 Ti0 2 . 79 .81 1. 09 . 63 . 95 Zr0 2 .07 co 2 None. . 12 None. . 11 PoO, . 28 Trace. . 27 . 70 1. 50 2 U 5 • so, . 07 .07 . 61 F .22 Cl .28 Trace. MnO .08 .10 Trace. .03 .08 . 19 . 17 BaO .05 .08 .24 . 76 SrO Trace. . 16 . 37 v,o, .02 Li 2 0 Trace. Trace. Trace. 99. 95 99. 96 99. 81 99. 98 99. 77 99. 61 99. 97 99. 93 446 THE DATA OF GEOCHEMISTRY. Analyses of deep-seated nephelite rocks — Continued. Norms. A comparison of these norms with the modes indicated in the de- scriptions of the rocks shows great divergencies. The normative and actual minerals are only in part the same. All of the rocks, however, consist dominantly of alkali feldspar and nephelite, with varying accessories. In the Brookville syenite the normative anorthite shows a gradation toward the plagioclase rocks. The urtite and ijolite rep- resent the highest proportions of nephelite; and in the theralite we have the femic minerals forming nearly one-half of the rock. Taken all together, the nephelite rocks, eruptive and plutonic, range from 1. 5. 1.4 to III. 7. 1.4. The miner alogical variations are great enough to justify a much more minute subdivision in classification than they are given here. The many varietal names that have been given the nepheline syenites follow from a recognition of their differences. Ditroite, foyaite, laurdalite, litchfieldite, urtite, and ijolite are exam- ples of this varied nomenclature. 1 1 A very full description of the Norwegian nepheline syenites is given by W. C. Brogger in his work Die Eruptivgesteine des Kristianiagebietes, especially in part 3 (1898). Laurdalite, heumite, nepheline por- phyry, foyaite, and hedrumite are the nephelite rocks described in this memoir. A remarkable rock found in Dungannon Township, Ontario, has been described by F. D. Adams, Am. Jour. Sci., 4th ser., vol. 17, 1904, p. 269. It contains 72.2 per cent of nephelite, with 15.09 of hornblende and 5.14 of cancrinite. Some minor constituents are also present. This rock Adams has named monmouthite, and its norm differs widely from its mode. On the origin of “alkaline” rocks see H. I. Jensen, Proc. Linn. Soc. New South Wales, vol. 33, 1908, p. 491; R. A. Daly, Bull. Geol. Soc. America, vol. 21, 1910, p. 87; and C. H. Smyth, jr., Am. Jour. Sci., 4th ser., vol. 36, 1913, p. 33. IGNEOUS ROCKS. 447 LETJCITE ROCKS. The leucite-bearing rocks are much less common than those carry- ing nephelite, and, like the latter, have been designated by various names. The following examples among those containing little or no soda-lime feldspar will suffice to show their composition: Analyses of leucite rocks. A. Pseudoleucite-sodalite tinguaite, Bearpaw Mountains, Montana. Analysis by H. 1ST. Stokes. De- scribed by W. H. Weed and L. V. Pirsson. Contains orthoclase, nephelite, sodalite, noselite, segirite, diopside, and fluorite. Magmatic symbol, II.7.1.3. Janeirose. Although leucite is not reported here, it appears abundantly in the norm. B. Arkite, or leucite syenite, Magnet Cove, Arkansas. Described and analyzed by H. S. Washington, Jour. Geology, vol. 9, 1901, p. 616. Contains, in percentages, orthoclase, 3.9; leucite, 36.9; nephelite, 25.5; aegirite, 8.4; diopside, 10.8; garnet, 14.5. Symbol, II.9.1.3. Arkansose. C. Wyomingite, Boar’s Tusk, Leucite Hills, Wyoming. Analysis by W. F. Hillebrand. Described by W. Cross. Contains phlogopite, leucite, diopside, and apatite. Symbol, III.6.1.1. Wyomingose. D. Leucitite, Bearpaw Mountains, Montana. Analysis by Stokes. Described by Weed and Pirsson as an olivine-free leucite basalt. Contains leuc’te, augite, iron oxides, rarely biotite, and a little glassy base. Symbol, III.8.1. 2. Chotose. E. Leucitite, Alban Hills, Italy. Described and analyzed by Washington, Am. Jour. Sci., 4th ser., vol. 9, 1900, p. 53. Contains leucite, nephelite, melilite, diopside, magnetite, a trace of biotite, and scarcely any apatite. Symbol, III.8.2. 2. Albanose. F. Madupite, Leucite Hills, Wyoming. Analysis by Hillebrand. Described by Cross. Contains diopside and phlogopite, with perofskite and magnetite, in a glassy base of nearly the composition of leucite. Symbol, III.9.1.2. Madupose. G. Missourite, Highwood Mountains, Montana. Analyzed by E. B. Hurlbut. Described by Weed and Pirsson in Bull. U. S. Geol. Survey No. 237, 1905. Contains leucite, augite, biotite, olivine, apatite, iron ore, some zeolites, and analcite. Symbol, IV. 1.1.2. In this rock', as the symbol indicates, femic minerals are dominant. A B C D E F G Si0 2 51. 93 44. 40 50. 23 46. 51 45. 99 42. 65 46. 06 ai 2 o 3 20. 29 19. 95 11. 22 11.86 17. 12 9. 14 10. 01 Fe 2 0 3 3. 59 5. 15 3. 34 7. 59 4. 17 5. 13 3. 17 FeO 1. 20 2. 77 1. 84 4. 39 5. 38 1.07 5. 61 MgO .22 1. 75 7. 09 4. 73 5. 30 10. 89 14. 74 CaO 1. 65 8. 49 5. 99 7. 41 10. 47 12. 36 10. 55 Na 2 0 8. 49 6. 50 1.37 2. 39 2. 18 .90 1. 31 k 2 o 9. 81 8. 14 9. 81 8. 71 8. 97 7. 99 5. 14 H 2 0- . 10 .24 . 93 1. 10 2. 04 h 2 o+ .99 1. 17 1. 72 2. 45 .45 2. 18 1 1.44 Ti0 2 .20 1. 53 2. 27 .83 .37 1. 64 ^7 CO Zr0 2 .03 C0 2 .25 . 12 None. P 2 0 6 .06 . 37 1. 89 . 80 1. 52 . 21 S0 3 . 67 .06 . 74 . 05 . 58 .05 Cl . 70 .03 . 04 . 03 .03 F . 27 . 50 Trace. . 47 Cr 9 0, . 10 None. . 07 Di 2 0 3 .03 . 11 MnO Trace. .08 .05 .02 Trace. .12 Trace. NiO .04 BaO .09 .01 1.23 .50 .45 .89 .32 SrO . 07 . 24 . 16 None. . 33 .20 Li 2 0 Trace. Trace. Trace. Trace. 100. 58 100. 76 100. 62 99. 78 100. 65 100. 11 99. 57 448 THE DATA OF GEOCHEMISTRY. Analyses of leudte rocks — Continued. Norms. It is worthy of note that there are many rocks specifically desig- nated as leucite-bearing which, as interpreted by Washington, reveal no leucite in the norms. 1 It is also to be observed that the leucite rocks are all effusive and never deep seated; at least no plutonic member of the group is known. In an abyssal rock, which has con- solidated under pressure, water is retained; and in such cases, when magnesium and potassium available for the formation of olivine and leucite are present, biotite is produced instead. Under ordinary cir- cumstances the fusion of biotite yields olivine, leucite, some glass, and a little spinel. 2 By fusing biotite and microcline together, Fouque and L6vy 3 obtained a mixture of leucite, olivine, and mag- netite, together with a mineral resembling melilite, which, however, could not be that species. A magma, then, which would form biotite under pressure, will lose water if it solidifies at the surface of the earth, and may generate olivine and leucite. The other lenad minerals, sodalite, noselite, and haiiynite, are also noteworthy constituents of certain rare rocks, which we need not consider in detail. Sodalite syenite, haiiynophyre, and nosean sani- dinite are names of rocks in which these minerals are conspicuous. 4 One sodalite syenite, however, is included in the next table of analyses, for the reason that it also contains analcite, a rock-making mineral whose significance has been realized only within recent years. 1 On the formation of leucite in igneous rocks, see H. S. Washington, Jour. Geology, vol. 15, 1907, pp. 257, 357. Also in his Roman comagmatic region, Pub. No. 51 Carnegie Inst., Washington, 19C6. 2 See H. Backstrom, Geol. Foren. Forhandl., vol. 18, 1896, p. 155. 3 Synthase des min^raux et des roches, p. 77. * For analyses see Washington’s Tables, Prof. Paper U. S. Geol. Survey No. 14, 1903, pp. 201, 215, 303, 305, 349, 351. IGNEOUS ROCKS. 449 ANALCITE ROCKS. The occurrence of analcite as a primary mineral was first recog- nized by W. Lindgren , 1 who described certain rocks from Montana as analcite basalts. In them the analcite played a part like that usually taken by the feldspars. Since then the mineral has been identified in a considerable number of other rocks , 2 and W. Cross 3 has found it to be commonly present in the phonolites of Cripple Creek. According to L. V. Pirsson , 4 the supposed “ glass base” of monchiquite is really analcite. This rock was originally described by M. Hunter and H. Rosenbusch 5 as consisting of olivine, with either amphibole, pyroxene, or biotite, or all three, in a glassy ground- mass; but the composition of the latter is that of analcite, and like analcite it gelatinizes with weak acids. In a magma having the general composition of a nepheline rock, the presence or absence of water is an important factor. If water is retained, analcite is likely to be formed; if lost, then nepheline is generated. Analcite, however, is more nearly akin, structurally, to leucite than to nephe- lite, and between the leucite and analcite rocks there are strong resemblances. The following analyses represent the last-named rock family: 6 1 Proc. California Acad. Sci. 2d ser., vol. 3, 1891, p. 51. 2 See citations under analcite in Chapter X, ante, p. 370. 2 Sixteenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1896, p. 32. « Jour. Geology, vol. 4, 1896, p. 679. * Min. pet. Mitt., vol. 11, 1890, p. 454. 0 On the analcite rocks of Sardinia, see H. S. Washington, Jour. Geology, vol. 22, 1914, p. 742. A remarka- ble rock, blairmorite, containing 71 per cent of analcite, found near Crowsnest Pass, Alberta, is described by J. D. MacKenzie, Dept. Mines, Canada, Museum Bull. No. 4, 1914. Analysis by M. F. Conner on p. 23. 97270°— Bull. 616—16 29 450 THE DATA OF GEOCHEMISTRY. Analyses of analdte rocks. A. Sodalite syenite, Square Butte, Highwood Mountains, Montana. Analysis by W. H. Melville. Described by W. Lindgren, Am. Jour. Sci., 3d ser., vol. 45, 1893, p. 286. Contains, in percentages, ortho- clase, 50; albite, 16; hornblende, 23; sodalite, 8; analcite, 3. Magmatic symbol I.5.2.3. Pulaskose. B. Analcite tinguaite, Manchester, Massachusetts. Analyzed and described by H. S. Washington, Am. Jour. Sci., 4th ser., vol. 6, 1898, p. 182. Contains, in percentages, analcite, 37.4; albite, 20.9; nephelite, 10.9; orthoclase, 17.3; segirite, 10.2; pyroxene, 3.3. Symbol I.6.I.4. Miaskose. C. Heronite, Heron Bay, Lake Superior. Analysis by H. W. Charlton. Described by A. P. Coleman, Join:. Geology, vol. 7, 1899, p. 431. Contains, in percentages, analcite, 47.0; orthoclase, 28.24; labradorite, 13.0; segirite, 4.04; limonite, 3.59; calcite, 1.96. Symbol, I.6.I.4. Miaskose. D. Monchiquite, Little Belt Mountains, Montana. Analysis by H. N. Stokes. Described by W. H. Weed and L. V. Pirsson. Contains olivine, augite, biotite, analcite, and apatite, with traces of serpentine and chlorite. Symbol, III.6.1.4. No subrang name assigned. Called analcite basalt in Washington’s tables. E. Monchiquite, Cabo Frio, Brazil. Described by Hunter and Rosenbusch, Min. pet. Mitt., vol. 11. 1890, p. 445. Analysis by M. Hunter. The type of monchiquite, as described above. Symbol, III.6.2.4. Monchiquose. F. Monchiquite, Big Baldy, Little Belt Mountains, Montana. Analysis by W. F. Hillebrand. De- scribed by Weed and Pirsson. Contains pyroxene, a few serpentinized olivines, iron ore, and apatite, in a base of analcite. Symbol, III.6.2.4. Monchiquose . G. Monchiquite, Highwood Mountains, Montana. Analysis by H. W. Foote. Described by Weed and Pirsson. Contains augite, olivine, biotite, iron ore, apatite, and analcite, with some serpentine and a little kaolin. Symbol, III.6.2.4. Monchiquose. H. Analcite basalt, near Cripple Creek, Colorado. Analysis by Hillebrand. Described by W. Cross. Contains augite, olivine, analcite, alkali feldspars, biotite, and apatite. Symbol, III.6.2.4. Monchiquose. A B c D E F G H SiO, 56. 45 56. 75 52. 73 48. 39 46. 48 48. 35 47. 82 45. 59 A1 2 0 3 20. 08 20. 69 20. 05 11. 64 16. 16 13. 27 13. 56 12. 98 Fe 2 0 3 1. 31 3. 52 3. 43 4. 09 6. 17 4. 38 4. 73 4. 97 FeO 4. 39 .59 .99 3. 57 6. 09 3.23 4. 54 4. 70 MgO : .63 .11 . 17 12. 55 4. 02 8. 36 7. 49 8. 36 CaO 2. 14 .37 3. 35 7. 64 7. 35 9. 94 8. 91 11. 09 Na 2 0 5. 61 11. 45 7. 94 4. 14 5. 85 3. 35 4. 37 4. 53 K 2 0 7. 13 2. 90 4. 77 3.24 3. 08 3. 01 3. 23 1.04 h 2 o- .26 .04 .69 .28 l A 9*7 .90 l Q 9*7 .51 h 2 o+ 1. 51 3. 18 4. 85 2. 56 > *k. Z/ 2.89 >0.0/ 3. 40 Ti0 2 .29 .30 . 73 .99 .52 . 67 1. 32 Zr0 2 .03 co 2 .93 .45 .30 P 9 (X . 13 Trace. .45 .40 1 . 10 . 91 SO, Trace. . 08 Trace. Cl .43 . 28 Trace. .04 .05 F . 25 Cr 2 0 3 .07 Trace. MnO . 09 Trace. Trace. . 19 Trace. . 14 NiO Trace. . 04 BaO None. . 11 .32 . 54 . 16 .13 SrO... . 15 . 09 . 21 .12 Li 2 0 Trace. Trace. 100. 45 100. 18 100. 01 99. 90 100. 91 100. 01 100. 20 99. 87 IGNEOUS ROCKS. 451 Analyses of analcite rochs — Continued. Norms. A B C D E F G H or 41. 7 17. 2 28. 4 18. 9 18.3 17. 8 18. 9 6. 1 ab 28. 3 46.6 30. 9 14. 7 14. 1 14. 7 17. 8 18. 9 an 10. 6 5. 0 3. 6 8. 6 12. 2 7. 8 12. 2 ne 3.4 23.6 19.6 11. 1 19.0 7.4 10.5 10.2 so 5.9 ac 6. 0 di .5 1.0 24.4 22.3 27.2 23.9 30.0 wo .5 ol 6. 1 4. 4 15. 2 2. 9 6. 7 7.4 6. 5 mt 1.9 2.0 3. 2 5.8 9.0 7.2 8.0 7.2 hm 1.1 il .6 1. 4 1.8 .9 1. 2 2. 5 ap 1.1 1.0 2.5 1.9 w r In these norms analcite is represented by normative nephelite; and biotite, in part, by olivine. The anorthite in some of them indicates a shading toward the plagioclase rocks. THE MONZONITE GROUP. The rhyolite-granite series of rooks, and the trachyte-syenite series also, are defined by the predominance in them of alkali feldspars, and commonly of orthoclase. The andesite-diorite series, on the other hand, is characterized by plagioclase feldspars; but between these rocks and those already described there are all sorts of gradations. Between the orthoclase and plagioclase rocks, therefore, considera- tions of convenience have led to the formation of an intermediate group, whose granitoid members are known as monzonites. Quartz monzonite corresponds to granite, monzonite to syenite, and so on. The effusive equivalents, intermediate between trachyte and andesite, have been named latites. All of these rocks carry orthoclase or anorthoclase with plagioclase in approximately equal amounts, with or without quartz, and with smaller amounts of the ferromagnesian silicates. The next table of analyses represents members of this intermediate group. 452 THE DATA OF GEOCHEMISTRY, Analyses of monzonites and latites. A. Quartz monzonite, Hailey, Idaho. Analysis by W. F. Hillebrand. Described by W. Lindgren. Contains quartz, orthoclase, microcline, oligoclase, biotite, apatite, titanite, and magnetite. Magmatic symbol, 1.4.2. 3. Toscanose. B. Quartz monzonite, Telluride quadrangle, Colorado. Analysis by H. N. Stokes. Described by W- Cross. Contains orthoclase and plagioclase in nearly equal amounts, quartz, augite, hornblende, biotite, magnetite, and apatite. Symbol, 1.4.2. 3. Toscanose. C. Biotite-augite latite, near Clover Meadow, Tuolumne County, California. Analysis by Hillebrand. Described byF. L. Ransome. Co ntains plagioclase, biotite, augite, magnetite, apatite, and glass. Symbol 1.4.2. 3. Toscanose. D. Monzonite, Tintic district, Utah. Analysis by Stokes. Described by G. W. Tower and G. O. Smith- Contains orthoclase, plagioclase, quartz, hornblende, biotite, magnetite, apatite, zircon, and titanite, with a little chlorite and epidote. Symbol, II.4.3.3. Harzose. E. Monzonite (yogoite), Yogo Peak, Little Belt Mountains, Montana. Analysis by Hillebrand. De- scribed by W. H. Weed and L. V. Pirsson. Contains orthoclase, oligoclase, pyroxene, hornblende, biotite, apatite, titanite, iron ore, and a little kaolin. Symbol, II. 5. 2. 3. Monzonose. F. Augite latite, Dardanelle flow, Tuolumne County, California. Analysis by Stokes. Described by Ransome. Contains plagioclase, augite, iron ore, some olivine, apatite, and brown glass. Symbol, n.5.2.3- Monzonose. G. Augite latite. Table Mountain , Tuolumne County, California. Analysis by Hillebrand. Described by Ransome. Contains labradorite, olivine, augite, and magnetite. Symbol, II.5.3.3. Shoshonose. H. Monzonite, La Plata Mountains, Colorado. Analysis by Stokes. Described by Cross. Contains orthoclase and plagioclase in nearly equal amounts, augite, hornblende, quartz, titanite, magnetite, and apatite. Symbol, II. 5.3.4. Andose. A B C D E F G H Si0 2 68. 42 65. 70 62. 33 59. 76 54. 42 59. 43 56. 19 57. 42 A1 2 0 3 15. 01 15. 31 17. 30 15. 77 14. 28 16. 68 16. 76 18. 48 Fe 9 0o .97 2. 54 3. 00 3. 77 3. 32 2. 54 3. 05 3. 74 FeO 1. 93 1. 62 1. 63 3. 30 4. 13 3. 48 4. 18 2. 10 MrO 1. 21 1. 62 1. 05 2. 16 6. 12 1. 84 3. 79 1. 71 CaO 2. 60 2. 56 3. 23 3. 88 7. 72 4. 09 6. 53 6. 84 Na 2 0 3. 23 3. 62 4.21 3. 01 3. 44 3. 72 2. 53 4. 52 k 2 o 4. 25 4. 62 4. 46 4. 40 4. 22 5. 04 4. 46 3. 71 h 2 o- .54 . 17 .44 .31 .22 .27 .34 .08 h 2 o+ .73 .42 .75 1. 11 .38 . 72 .66 .28 Ti0 2 .50 .72 1. 05 .87 .80 1. 38 .69 .86 Zr0 2 .04 .08 co 2 .20 None. . 78 None. P 9 0. . 13 .33 .29 .42 .59 .58 .55 .36 s? .02 None. so 3 . 12 None. None. Cl .03 .04 .05 .03 VoOo . 01 .02 MnO .06 Trace. .08 . 12 . 10 Trace. . 10 .09 BaO . 12 . 12 .24 .09 .32 . 14 . 19 . 15 SrO .03 .03 .05 Trace. . 13 Trace. Trace. .08 Li 2 0 Trace. Trace. Trace. Trace. None. Trace. Trace. FeS 2 .06 C .11 99. 95 99. 53 100. 33 99. 81 100. 19 100.04 100. 02 100. 45 Norms. A B C D E F G H Q 25. 1 19. 1 12.4 14. 6 8.4 5.9 4.0 or 25. 6 27.2 26. 7 26. 1 25.0 29.0 26. 7 21. 7 ab 26. 7 30.4 35. 6 24. 1 28. 8 30. 9 21. 5 37. 7 an 13. 1 12. 1 15.0 16.7 11.1 13.9 20.9 20.0 C .3 .4 di .8 2.4 19. 1 2.3 6.8 8.7 hy 5.0 4. 1 2.3 5.8 9. 9 5.8 10. 1 mt 1.4 3.5 2. 1 5.6 2.6 3.5 4.6 5.3 hm 1. 6 il .9 1.4 2.0 1.7 1.5 2.6 1.2 1.5 ap 1.3 1.4 1.2 1.0 IGNEOUS ROCKS. 453 THE ANDESITE-DIORITE SERIES. From the monzonite group to the dacites and quartz diorites the gradation is very slight. These rocks, which mark the persilicic end of the andesite-diorite series, are characterized by quartz, with plagioclase as the prevailing feldspar, and with subordinate amounts of femic minerals. The dacites are eruptive rocks; the quartz diorites are their granitoid or plutonic equivalents. They correspond to rhyolite and granite in the orthoclase series, and between dacite and quartz diorite there are porphyritic forms analogous to the quartz porphyries. For dacites and quartz diorites a single group of analyses must suffice, as follows: Analyses of dacites and quartz diorites. A. Dacite, Bear Creek Falls, Shasta County, California. Analysis by R. B. Riggs. Described by J. S. Diller. Contains plagioclase, with a little sanidine, hornblende, quartz, magnetite, some pyroxene inclu- sions, and glass. Magmatic symbol, I.4.2.4. Lassenose. B. Quartz diorite, near Enterprise, Butte County , California. Analysis by W. F. Hillebrand. Reported by H. W. Turner to contain plagioclase, potash feldspar, quartz, hornblende, mica, and accessories. Sym- bol, I.4.2.4. Lassenose. C. Dacite, Sepulcher Mountain, Yellowstone National Park. Analysis by J. E. Whitfield. Described by J. P. Iddings. Contains plagioclase, quartz, biotite, and hornblende. Symbol, I.4.3.4. Yellowstonose. D. Quartz diorite, Pigeon Point, Minnesota. Analysis by Hillebrand. Described by W. S. Bayley. Contains feldspar, quartz, hornblende, chlorite, magnetite, apatite, and rutile. Symbol, II.4.2.3. Adamellose. E. Quartz-mica diorite, near Milton, Sierra County, California. Analysis by Hillebrand. Described by Tinner. Contains plagioclase, quartz, hornblende, brown mica, iron ore, and apatite. Harzose. F. Quartz-mica diorite, Electric Peak, Yellowstone National Park. Analysis by Whitfield. Described by Iddings. Contains plagioclase, orthoclase, quartz, biotite, hornblende, augite, and hypersthene. gyrnbol, II.4.3.4. Tonalose. G. Quartz-mica diorite, Yaqui Creek, Mariposa County, California. Analysis by G. Steiger. Described by Turner. Contains plagioclase, quartz, biotite, hornblende, a little pyroxene, iron ore, and apatite. Symbol, II.4.3.4. Tonalose. H. Quartz-mica-hornblende diorite, Stone Run, Cecil County, Maryland. Analysis by Hillebrand. Described by A. G. Leonard. Contains hornblende, biotite, quartz, plagioclase, a little orthoclase, zircon, apatite, titanite, and magnetite, with secondary chlorite and epidote. Symbol, II.4.4.3. Bandose. Si0 2 . . A1 2 0 3 . Fe 2 0 3 . FeO... MgO. . CaO... Na 2 0.. K 2 0... h 2 o-. h 2 0+. Ti0 2 . . Zr0 2 . . C0 2 ... £A-- so 3 — Cl VA- MnO.. BaO. . SrO... Li 2 0 . . C 68. 10 15. 50 3. 20 None. .10 3. 02 4. 20 3. 13 2. 72 .15 .03 Trace. .06 Trace. None. B 70. 36 15. 47 .98 1. 17 .87 3. 18 4. 91 1. 71 .06 1. 00 .20 11 Trace. .06 Trace. Trace. 100.21 100.08 100.27 65. 66 15. 61 2. 10 2. 07 2. 46 3. 64 3. 65 2. 03 \ 1.07 1.37 Trace. .13 .12 None. .36 57. 98 13. 58 3. 11 8. 68 2. 87 2. 01 3. 56 3. 44 \ 2.47 1. 75 .29 Trace. .13 .04 Trace. Trace. 99. 91 57. 26 6. 51 3. 27 5. 19 3. 41 6. 69 2. 65 2. 93 .20 .95 .53 .30 .18 .10 .06 Trace. 100. 23 65. 11 16. 21 1. 06 3. 19 2. 57 3. 97 4. 00 2. 51 \ .94 .71 .02 Trace. None. None. .04 100. 33 G 58. 09 17. 46 1. 12 5. 08 4. 06 6. 24 2. 94 2. 02 .29 1. 45 .95 .21 .17 .05 .02 None. .07 .04 None. .11 58. 57 16. 10 2. 89 6. 12 2. 33 7. 39 2. 11 1. 01 .21 1. 27 1.41 .09 None. .37 .02 .18 Trace. Trace. Trace. 100. 37 100. 07 454 THE DATA OF GEOCHEMISTRY. Analyses of dacites and quartz diorites — Continued. Norms. A B C D E F G H Q 25.4 27. 1 25.0 11. 1 10. 3 18. 5 11. 2 21. 3 or 18. 3 10. 0 12.2 20. 0 17. 2 15. 0 12.2 6. 1 ab 35. 6 41.4 30. 9 29. 9 22. 5 33. 5 24. 6 17. 8 an 14.2 15.3 18. 1 10.0 24.5 18.9 28.4 31.4 C . 7 .5 di 7. 3 .8 2. 1 4.5 hv .7 3.1 6.2 17.7 10.9 9. 7 16.0 10.0 mt, 1.6 2.8 8.0 4.6 1.6 1.6 4.2 hm 3.2 il .5 2.6 3.4 1.1 1.4 1.8 2.8 tn .4 With these rocks it must be borne in mind that normative ortho- clase in part represents biotite. The actual orthoclase, therefore, will be less in amount than appears in the norms. Dacite is a quartz andesite; and the andesites which are poor or lacking in quartz form a group of rocks parallel with the trachytes. They contain plagioclase as a principal constituent, with subordinate biotite, hornblende, or pyroxene. Six analyses of andesites are given in the next table. IGNEOUS ROCKS. 455 Analyses of andesites. A. From Pikes Peak, Colorado. Analysis by W. F. Hillebrand. According to W. Cross, it contains plagioclase, orthoclase (?), augite, iddingsite, hypersthene, flakes of limonite, and a little tridymite. Magmatic symbol, I.5.2.3. Pulaskose. B. From Silver Cliff, Colorado. Analysis by L. G. Eakins. Described by Cross. Contains plagioclase, orthoclase, augite, biotite, hornblende, quartz, magnetite, and apatite. Symbol, II.5.2.4. Akerose. C. Augite andesite, Dike Mountain, Yellowstone National Park. Analysis by Hillebrand. According to Arnold Hague and T. A. Jaggar it contains plagioclase, augite, apatite, magnetite, and serpentinized olivine. Symbol, II.5.3.3. Shoshonose. D. Augite-bronzite andesite, Unga Island Alaska. Analysis by Hillebrand. Described by G. F. Becker. Contains plagioclase, augite, bronzite, a little glass, and some indeterminate material. Symbol, II.5.3.4. Andose. E. Hypersthene andesite, Franklin Hill, Plumas County, California. Analysis by Hillebrand. Reported by H. W. Turner to contain plagioclase, rhombic pyroxene, augite, and magnetite. Symbol, II.5.4.3. Hessose. F. Augite andesite, near Electric Peak, Yellowstone National Park. Analysis by Hillebrand. Described by J. P. Iddings. Contains plagioclase, malacolite, actinolite, and magnetite. Symbol, HI.5.3.3. Kentallenose. A B C D E F Si0 2 62. 64 57. 01 51. 17 56. 63 56. 88 50. 59 17. 82 18. 41 16. 14 16. 85 18. 25 11.49 Fe 2 0 3 3. 91 3. 69 4. 11 3. 62 2. 35 1. 83 FeO .31 2. 36 4. 48 3. 44 4. 45 7. 64 MgO .47 2. 34 4. 82 4. 23 4. 07 11. 27 CaO 3. 22 4. 29 7. 72 7. 53 7. 53 8. 79 4. 47 4. 95 2. 99 3. 08 3. 29 2. 27 k 2 6 4. 99 3. 72 3. 54 2. 24 1.42 2. 33 h 2 o- .58 l 9 9Q .63 .80 .24 .21 h 2 o+ .65 2. 24 .51 .50 1. 76 Ti0 2 .59 .27 1. 01 .67 .45 .80 Zr0 2 .08 None. PA .25 .42 .48 .16 .30 .48 .04 .04 .04 MnO .04 .21 .21 .23 .18 .17 NiO .01 Trace? .06 BaO .28 .20 .09 .11 .10 SrO .07 . 10 Trace. .04 .03 T,i„0 Trace. Trace. Trace. Trace. FeS 2 .05 .06 100. 37 99. 96 99. 94 100. 18 100. 06 99. 86 Norms. A B c D E F Q 10.2 2.2 9.1 9. 1 30.0 22.2 20.6 13.3 8.3 13.8 ab 37.7 41.9 25.2 26.2 27.8 19.4 an 13.6 16.7 20.3 25.3 30.9 13.9 di 1.8 1.7 12.4 9.1 5.3 22.4 hy .4 5.9 8.5 8.4 13.2 8.7 ol .6 14. 1 mt 5.3 5. 8 5.3 3. 5 2.6 hm 3.9 il .6 .5 1.8 1.2 .8 1.5 an 1.0 1. 1 1.0 Diorite is the plutonic equivalent of andesite. It is commonly defined as a granitoid rock consisting chiefly of plagioclase, with 456 THE DATA OF GEOCHEMISTRY. either biotite or hornblende, or both; but many diorites carry pyrox- ene also, and shade into the gabbros. In fact, as the femic minerals become more prominent in rocks the problems of classification become more complex, and the results are less satisfactory than with the similar mixtures of feldspar and quartz. A variety of diorite is called “camptonite.” Tonalite and kersantite are other varieties. The following analyses represent the diorite group: Analyses of diorites. A. Diorite, Mount Ascutney, Vermont. Analysis by W. F. Hillebrand. Described by R. A. Daly. Contains hornblende, augite, biotite, plagioclase, titaniferous magnetite, titanite, zircon, and quartz. Magmatic symbol, II.5.2.3. Monzonose. B . Diorite porphyry, La Plata Mountains, Colorado. Analysis by Hillebrand. Described by W. Cross. Contains hornblende, plagioclase, orthoclase, quartz, titanite, apatite, and magnetite, with secondary epidote, chlorite, and calcite. Symbol, II.5.2.4. Akerose. C. Diorite, Crazy Mountains, Montana. Analysis by Hillebrand. According to J. E. Wolff it contains biotite, labradorite, augite, orthoclase, quartz, magnetite, apatite, and hornblende. Symbol, II.5.3.3. Shoshonose. D. Tonalite, South Leverett, Massachusetts. Analysis by L. G. Eakins. Described by B. K. Emerson. Contains feldspar, hornblende, and epidotic quartz veins. Symbol, II.5.3.4. Andose. E. Diorite, South Honcut Creek, Butte County, California. Analysis by Hillebrand. Reported by H. W. Turner to contain feldspar, hornblende, and a little chlorite. Symbol, II.5.3.5. Beerbachose. F. Camptonite, La Plata Mountains, Colorado. Analysis by Hillebrand. Reported by Cross to contain hornblende, augite, plagioclase, orthoclase, magnetite, apatite, and some secondary calcite. Symbol, III.5.3.3. Kentallenose. G. Camptonite, Mount Ascutney, Vermont. Analysis by Hillebrand. Described by Daly. Contains plagioclase, hornblende, a little augite, olivine, magnetite, and apatite. Symbol, III.5.3.4. Camptonose. H. Diorite, Hump Mountain, Mitchell County, North Carolina. Analysis by Hillebrand. Reported by A. Keith to contain plagioclase, orthoclase, hornblende, quartz, biotite, magnetite, andgarnet. Sym- bol, III.5.4.3. Auvergnose. A B C D E F G H Si0 2 57. 97 60.44 57. 97 55. 51 57. 87 47. 25 48. 22 46. 91 ai 2 o 3 17. 28 16. 65 15. 65 16. 51 16. 30 15. 14 14. 27 15. 85 Fe 2 0 3 2. 23 2. 31 .73 1. 68 1. 71 5. 05 2. 46 2. 86 FeO. 3. 75 3. 09 2. 80 4. 57 3. 86 4. 95 9. 00 9. 95 MgO 2. 20 2. 18 4. 96 6. 73 5. 50 6. 87 6. 24 7. 01 CaO 4. 33 4. 22 10. 93 6. 73 5. 53 9. 98 8. 45 9. 62 Na 2 0 4. 31 5. 18 3.03 3. 19 5. 01 2. 39 2. 90 2. 65 K 2 0 4. 12 2. 71 3. 16 2. 46 .75 2.60 1. 93 .69 h 2 o- .18 .36 .22 1 1 KQ .26 .40 .28 .24 h 2 o+ .57 1. 07 .38 > 1. Do 2. 40 2. 12 1. 66 1. 62 Ti0 2 1 1 KA .60 .60 .91 .53 1. 22 2. 79 2. 03 Zr0 2 > 1. 0*± .03 None. C0 2 .05 .48 1. 87 .15 PA .64 .29 .15 .17 .27 .25 .64 .26 Cl .10 F .04 Trace. .05 VoO,. .02 .05 .03 ▼ 2 vy 3 • Cr 2 0 3 .01 MnO .15 .13 Trace. .11 o 00 .17 .20 .22 (NiCo)O Trace. None. .02 .03 .03 BaO .07? .12 .09 .02 .05 .08 .04 Trace? SrO . 11 .02 Trace. .05 Trace? Li 2 0 Trace. Trace. Trace. Trace. Trace. FeS 2 - . . .32 None. .36 99. 75 99. 96 100. 69 100. 12 100. 12 100. 46 99. 80 99. 98 IGNEOUS ROCKS. 457 Analyses of diorites — Continued. Norms. A B C D E F G H 0 4. 9 7. 7 3.1 2.3 5.0 or 24.5 16.1 18.9 14.5 4.4 15.0 11.1 3.9 ab 37.2 44.0 25.7 26.7 41.9 17.8 24.6 22.5 an 15.0 13.9 19.5 23.4 20.3 22.8 20.3 29.2 ne 1.4 di 2.5 5.7 27.8 8.1 5.9 21.4 15.1 15.1 hy 6. 9 5.5 2. 7 18.4 16.5 9.2 8.1 ol. 7.2 6.4 10.7 mt. 3.2 3.2 1.2 2.6 2.3 7.4 3.5 4.2 il 2.9 1.2 1.1 1.7 1.1 2.3 5.4 3.8 1. 3 1.3 ! THE BASALTS. The basalts form an ill-defined group of lavas which vary from the andesites in containing a larger proportion of the femic minerals. Plagioclase, pyroxene, often olivine, and magnetite are the principal minerals of basalt, but many variations of it are known. Some basalts are free from olivine, other examples contain such minerals as leucite, nephelite, melilite, etc. Hornblende basalts are known, but they are rare. In a few basalts quartz has been identified, but its presence is anomalous and not well explained . 1 The following analyses relate to basalt, as the unqualified term is commonly used. 1 See J. S. Diller, Bull. U. S. Geol. Survey No. 79, 1891. 458 THE DATA OF GEOCHEMISTRY. Analyses of basalts. A. Basalt, early flow, Table Mountain, Colorado. Analysis by L. G. Eakins. Described by W. Cross. Contains augite, olivine, plagioclase, probably ortboclase, magnetite, apatite, and a little biotite. Mag- matic symbol, II.5.3.3. Shoshonose. B. Basalt, Saddle Mountain, Pikes Peak, Colorado. Analysis by W. F. Hillebrand. Described by Cross. Contains augite, olivine, plagioclase, orthoclase, magnetite, biotite, and apatite. Symbol, II.5.3.4. Andose. C. Quartz basalt, Cinder Cone, near Lassen Peak, California. Analysis by Hillebrand. Described by J. S. Diller. Contains plagioclase, pyroxene (mostly hypersthene), olivine, quartz, magnetite, augite sparingly, and much unindividualized base. Symbol, II.5.3.4. Andose. D. Basalt, San Joaquin River, Madera County, California. Analysis by Hillebrand. Reported by H. W. Turner to contain pyroxene, partly augite, plagioclase, olivine, and iron ore. Symbol, II.5.3.4. Andose. E. Basalt, McCloud River, near Mount Shasta, California. Analysis by H. N. Stokes. Not described. Symbol, II.5.4.3. Hessose. F. Basalt, San Rafael flow, Colfax County, New Mexico. Analysis by Hillebrand. According to Cross it contains plagioclase, augite, olivine, much iddingsite, magnetite, and apatite. Symbol, III.5.3.4. Camptonose. G. Basalt, Pine Hill, South Britain, Connecticut. Analysis by Hillebrand. Described by W. H. Hobbs. Contains plagioclase, augite, olivine, and magnetite. Symbol, III.5.4.3. Auvergnose. A B C D E F G Si0 2 49. 69 48. 76 57. 25 51. 89 47. 94 48. 35 52. 40 ai 2 o 3 18. 06 15. 89 16. 45 15. 28 18. 90 15. 47 13. 55 Fe 2 0 3 2. 64 6. 04 1. 67 3. 10 2. 21 4. 80 2. 73 FeO . 6.19 4. 56 4. 72 3. 60 8. 59 7. 58 9. 79 MgO 5. 73 5. 98 6. 74 8. 68 8. 21 8. 15 5. 53 CaO 8. 24 8. 15 7. 65 7. 38 9. 86 8. 81 10. 01 Na 2 0 2. 99 3. 43 3. 00 3. 27 2. 81 3. 09 2. 32 K 2 0 3. 90 2. 93 1. 57 2. 57 .29 .95 .40 H 2 0- \ qn .40 l AC\ 1. 17 .39 .28 .62 H 2 0+ •- - - / - 91 1. 48 1. 37 .74 .73 1. 05 Ti0 2 .85 1. 65 .60 .91 .57 1. 33 1. 08 p 2 0 6 .81 .60 .20 .61 .15 .33 .12 SOo . 07 ci 3 ;; . 13 MnO .13 .13 .10 .12 Trace. .21 .26 NiO .02 .02 Trace. BaO .17 .03 .15 None. .06 Trace. SrO .06 Trace. . 09 None. .03 None. Li 2 0 None. Trace. Trace. Trace. None. FeS 2 . 13 4 100. 27 100. 23 100. 38 100. 21 100. 66 100. 26 99. 99 Norms. A B c D E F G Q 6. 9 6.7 or 22. 8 17. 2 9. 5 15.0 1. 7 5. 6 2.2 ab 19.4 26. 7 25. 2 27. 8 23. 6 26. 2 19.4 an 24.5 19. 2 26.7 22.2 38.1 25.6 25.6 ne 3. 1 1.1 di 9.4 14.1 9.0 9.0 8. 9 14. 7 19.7 hy 18.9 7.9 5.9 6. 7 18.1 ol 12. 8 6. 5 7. 2 17. 0 10. 5 mt 3. 7 8. 6 2.3 4. 6 3. 2 7. 0 3.9 il 1.7 3. 1 1.1 1.7 1.1 2.5 2.2 ap 1.9 1.3 1.2 IGNEOUS ROCKS. 459 The following table contains analyses of a number of exceptional rocks, which are classed with the basalts, but vary from them in having the feldspar more or less replaced by leucite, nephelite, or melilite. The unique venanzite is placed here, as being more nearly akin to this group of rocks than to any other. The analcite basalts given in a previous table properly belong here also, and so perhaps do some of the rocks described in connection with the tables on pages 444-450. Analyses of basaltic rocks. A. Kulaite, Kula, Lydia, Asia Minor. Described and analyzed by H. S. Washington, Jour. Geology, vol. 8, 1900, p. 613. Contains, in percentages, anorthite, 17.9; albite, 8.4; orthoclase, 23.4; nephelite, 20.4; diopside, 12.8; olivine, 10.7; magnetite, 3.8; apatite, 1.8. The diopside is derived from hornblende. Magmatic symbol, II.6.2.4. Essexose. B. Leucite kulaite, Kula. Described and analyzed by Washington, loc. cit. Contains, in percentages, anorthite, 17.9; albite, 23.6; leucite, 17.4; nephelite, 12.8; diopside, 13.8; olivine, 9.5; magnetite, 3.7. Symbol, II.6.2.4. Essexose. C. Basalt, Pinto Mountain, Uvalde County, Texas. Analysis by W. F. Hillebrand. Described by W. Cross. Contains olivine, augite, plagioclase, magnetite, apatite, and a very little alkali feldspar. Symbol, III.6.3.4. Limburgose. D. Leucite basalt, Highwood Mountains, Montana. Analysis by H. W. Foote. Described by W. H. Weed and L. V. Pirsson. Contains augite, olivine, biotite, some leucite, analcite, iron ore, and apatite. Symbol, III.7.2.3. No subrang name given. E. Venanzite or euctolite, San Venanzo, Umbria, Italy. Described by H. Rosenbusch, Sitzungsb. Akad. Berlin, 1899, pt. 1, p. 111. Contains olivine, melilite, leucite, biotite, magnetite, some zeolites, and a trace of nephelite. Symbol, IV l 5 . 1.2. Venanzose . F. Nephelite basalt, Tom Munn’s Hill, Uvalde County, Texas. Analysis by Hillebrand. Described by Cross. Contains olivine, augite, nephelite, magnetite, and apatite. Symbol, IV.22.1.2. TJvaldose. G. Nephelite basalt, Black Mountain, Uvalde County, Texas. Analysis by Hillebrand. Described by Cross. Contains olivine, augite, nephelite, magnetite, and apatite. Symbol, IV.2 2 .1.2. TJvaldose. H. Nephelite-melilite basalt, near Uvalde, Texas. Analysis by Hillebrand. Described by Cross. Contains nephelite, melilite, olivine, augite, apatite, and magnetite. Symbol, IV.23.1.2. Casselose. A B C D E F G H Si0 2 48. 35 49. 90 45. 11 46. 04 41. 43 40. 32 39. 92 37. 96 A 1203 19. 94 19. 89 12.44 12. 23 9. 80 9.46 8 . 60 10. 14 Fe 2 0 3 2. 48 2 . 55 2. 67 3. 86 3. 28 4. 75 4. 40 3. 69 FeO 5. 25 4. 78 9. 36 4. 60 5. 15 7. 48 8 . 00 7. 59 MgO 5. 15 5. 05 11. 56 10. 38 13. 40 18. 12 10. 17 14. 69 CaO 7. 98 7. 21 10 . 61 8 . 97 16. 62 10 . 55 10 . 68 16. 28 Na 2 0 5. 47 5. 60 3. 05 2.42 1. 64 2 . 62 1. 91 2. 18 K 2 0 3. 99 3. 74 1 . 01 5.77 4 7.40 1. 10 1. 03 .69 H 2 0- .16 .13 .16 1 9 07 .57 .43 .39 h 2 o+ .22 .19 .78 > Zi.Oi i L ii 1 . 25 1. 45 1 . 82 Ti0 2 .12 .93 2. 34 .64 .29 2 . 66 2. 70 2. 93 PA .84 Trace. .51 1. 14 None. .68 .51 1. 13 s.... .01 .01 Trace. .04 so, Trace. Trace. .03 Cl .11 .11 .05 Trace . Trace. F Undet. .04 .07 .07 YA- .04 .04 .95 Cr 2 0 3 .14 .08 MnO Trace. Trace. .22 Trace. .25 .24 .22 NIO .04 .06 .06 .04 BaO Trace. .48 .06 .06 .06 SrO Trace. .25 .03 .04 .05 Li 2 0 None. Trace. Trace. Trace. 99. 95 99. 97 100. 02 99. 76 100. 12 100. 09 100. 45 100. 13 460 THE DATA OF GEOCHEMISTEY. Analyses of basaltic rocks — Continued. Norms. A B c D E F G H or 23.4 22. 4 6. 1 22.2 3.3 ab 8. 9 13. 6 13. 1 an 18. 1 18. 1 17. 2 5.3 11.1 12.0 18. 6 ne 20.1 18.2 6.8 11.1 4. 8 11.9 8.5 9.9 kp 25.0 lc. 9,6 2.6 4.9 3.1 ac 4.2 di 13. 4 14. 2 26. 4 26. 3 29. 3 24. 6 13. 5 ol 10.1 7. 6 19.8 12.3 32. 3 26.2 32. 1 26. 1 am 29. 8 2. 4 13. 8 mt 3.8 3. 7 3. 9 5. 6 2. 8 7. 0 6. 3 5.3 il. 1.7 4. 3 1. 2 .6 5. 1 5. 1 4.4 ap 1.8 1.1 2.6 1.6 1.2 2.6 Jr The appearance of normative kaliophilite in analysis E is very striking. The absence of normative leucite from the “ leucite kulaite ” is also noticeable. DIABASE. Intermediate in texture between basalt and the granitoid gabbros are the diabases, which, like basalt, are principally composed of pla- gioclase, augite, magnetite, and sometimes olivine. Their range of composition is fairly well shown in the next table. IGNEOUS ROCKS. 461 Analyses of diabase. A. Turnpike Creek, Kittitas County, Washington. Analysis by W. F. Hillebrand. Reported by G. O Smith to contain plagioclase, augite, olivine, magnetite, and apatite. Magmatic symbol, II.4.3.4. Tonalose. B. Grass Valley, Nevada County, California. Analysis by H. N. Stokes. Described by W. Lindgren. Contains feldspar, pyroxene, hornblende, ilmenite, pyrrhotite, pyrite, and chlorite, with probably a little quartz. Symbol, II.4.4.3. Bandose. C. Shoshone Canyon, Yellowstone National Park. Analysis by Hillebrand. Contains, according to Arnold Hague and T. A. Jaggar, plagioclase, augite, and chlorite. Symbol, II.5.3.4. Andose. D. Aroostook Falls, Maine. Analysis by Hillebrand. Description by H. E. Gregory. Contains pla- gioclase, pyroxene, pyrite, apatite, chlorite, and a little calcite. Symbol, II.5.3.5. Beerbachose. E. Diabase porphyry, near Milton, Sierra County, California. Analysis by Hillebrand. Described by H. W. Turner. Contains plagioclase, augite, and hornblende. Symbol, III.5.3.4. Camptonose. F. Mount Ascutney, Vermont. Analysis by Hillebrand. Described by R. A. Daly. Contains plagio- clase, augite, and magnetite. Symbol, III.5.4.3. Auvergnose. A B C D E F Si0 2 57. 21 53. 19 52. 18 49. 64 51. 27 49. 63 A1 2 0 3 12. 99 17. 12 18. 19 15. 07 12. 14 14. 40 Fe 2 0 3 3. 28 4. 35 3. 31 1. 66 2. 51 2. 85 FeO 10. 18 5. 16 4. 36 8. 82 6. 71 8. 06 MgO 1. 59 3. 98 4. 69 5. 43 10. 86 7. 25 CaO 5. 97 9. 39 ' 6.51 7. 23 10. 32 9.28 Na 2 0 3. 07 2. 79 4. 58 4. 19 2. 00 2. 47 K 2 0 1. 61 .28 1. 88 .89 1. 63 .70 H 2 0- .68 .17 .75 .45 . 17 .27 h 2 0+ 1.03 1. 21 2. 00 2. 81 1. 16 1. 47 Ti0 2 ....: 1. 72 1. 34 .99 2. 32 .60 1. 68 co 2 None. .32 1. 36 p 2 o 5 .44 .13 .29 .29 .21 .25 Cl Trace. . 07 v 2 o 3 None. .04 MnO .24 Trace. .14 .25 .21 .17 NiO Trace. Trace. Trace. . 04 . 04 BaO .06 Trace. .11 .02 .07 Trace? SrO Trace. . 06 .05 Trace? Li 2 0 Trace. Trace. Trace. FeS 2 . 13 . 94 . 79 . 22 100. 20 100. 05 100. 04 100. 27 99. 92 100. 17 Norms. A B C D E F Q 15.4 10. 4 1.5 or 9. 5 1. 7 11. 1 5.0 9.5 4.4 ab 26. 2 23. 6 38. 8 35. 6 16. 8 21.0 an 16. 7 33. 4 23. 4 19. 7 19. 5 25. 9 di 8. 9 10. 6 7. 2 13. 9 25. 4 16. 6 hy 12.5 9.5 3. 8 6. 0 16. 5 19. 8 ol 5.8 9. 0 5. 7 mt 4. 9 6. 3 4. 9 2.3 3. 5 4. 2 il 3.2 2. 5 1.8 _ 4.3 1.2 3.2 pr . 9 ap 1 . 0 462 THE DATA OF GEOCHEMISTRY. THE GABBROS. The gabbros, which are the granitoid equivalents of the basalts and diabases, consist mainly of plagioclase and pyroxene, with vari- ous admixtures of other minerals. At one end of the series we have anorthosite, or labradorite rock, which is almost entirely composed of feldspar; at the other end the plagioclase diminishes in amount, and the rocks approach the pyroxenites. Normal gabbro contains monoclinic pyroxene; in norite, rhombic pyroxene, usually hyper- sthene, appears. The gabbro family is a large one, with many varie- ties of rock, and only a few examples of it are covered by the subjoined table. Analyses of gabbros. A. Anorthosite, Monhegan Island, Maine. Analyzed and described by E. C. E. Lord, Am. Geologist, vol. 26, 1900, p. 340. Nearly pure plagioclase. Magmatic symbol, 1.5.5. Canadase. B. Gabbro, near Emigrant Gap, Placer County, California. Analysis by W. F. Hillebrand. Described by W. Lindgren. Contains biotite, hypersthene, diallage, plagioclase, and orthoclase. Symbol, II.5.3.4. Andose. C. Gabbro, Emigrant Gap, California. Analysis by Hillebrand. Described by Lindgren. Contains hypersthene, diallage, plagioclase, and orthoclase. Symbol, III.4.3.4. Vaalose. D. Norite, Elizabethtown, Essex County, New York. Analysis by Hillebrand. Described by J. F. Kemp. Contains labradorite, hypersthene, garnets, augite, hornblende, biotite, magnetite, and apatite. Symbol, III.5.3.4. Camptonose. E. Bronzite norite, Crystal Falls, Michigan. Analysis by G. Steiger. Described by J. M. Clements and H. L. Smyth. Contains bronzite, hornblende, and labradorite. Symbol, HI.5.4.3. Auvergnose. F. Olivine gabbro, Birch Lake, Minnesota. Analysis by H. N. Stokes. Contains a large proportion of diallage and olivine. Symbol, III.5.4.3. Auvergnose. G. Hypersthene gabbro, Wetheredville, Maryland. Analysis by Hillebrand. Described by G. H. Williams. Contains hypersthene, diallage, plagioclase, magnetite, and apatite. Symbol, HI.5.5. Keda. bekase. H. Hypersthene gabbro, Gunflint Lake, Minnestota. Analysis by St okes. Described by W. S. Bayley Contains hypersthene, biotite, diallage, magnetite, and plagioclase. Symbol, IV.1.1.2. Cookose. A B C D E F G H Si0 2 45. 78 55. 40 55. 87 47. 16 48. 23 45. 66 44. 76 46. 96 A1 2 0 3 30. 39 15. 32 13. 52 14. 45 18. 26 16.44 18. 82 14. 13 Fe 2 0 3 1.33 2. 70 2. 70 1. 61 1. 26 .66 2. 19 .76 FeO | 1.22 5. 49 5. 89 13. 81 6. 10 13. 90 4. 73 14. 95 MgO 1 2.14 5. 75 6. 51 5. 24 10. 84 11.57 11. 32 15. 97 CaO 16.66 9. 90 8. 87 8. 13 9. 39 7. 23 14. 58 2. 32 Na 2 0 1.66 2. 89 2. 42 3. 09 1. 34 2. 13 .89 .35 K 2 0 .10 1. 52 1. 72 1. 20 .73 .41 .11 1. 68 h 2 o- 1 51 .03 .09 .12 .26 .07 .17 .07 h 2 o+ / * 51 .38 1. 56 .48 2. 00 .83 2. 36 1. 26 Ti0 2 .60 .56 3. 37 1. 00 .92 .13 .62 co 2 .35 .43 P 9 CL .22 .25 .57 .07 .05 None. .03 s . 14 VoO, (?) *2X3 CToO-5 Trace. .08 TVace. VA 2 v/ 3 MnO .11 . 10 .24 Trace. .15 .93 NiO .02 . 16 .06 BaO .07 .02 Trace. SrO None. None. Li a O Trace. Trace. Trace. 99. 79 100. 38 100. 08 99. 98 99. 91 100. 03 100. 29 100. 09 IGNEOUS ROCKS. 463 Analyses of gabbros — Continued. Norms. A B C D E F G H 0 5. 1 8.0 or 0. 6 8. 9 10.0 7.2 3. 9 2.2 0. 6 10.0 ab 12. 1 24. 6 20.4 26.2 11.0 17. 8 7.3 3.1 an 75. 1 .24.2 20.9 22.0 42.0 34.2 47.0 11.4 ne 1.1 C 7.5 di 6.1 20. 5 19. 0 12. 5 3. 9 1.4 20. 1 hy 11.4 14.6 8. 1 29.9 10. 1 3. 1 57.5 ol 2.5 12.8 2.9 30.3 16.0 6.0 mt. 1.9 3. 9 3.9 2.3 1.9 .9 3.2 1.2 il LI 1.1 6.4 1.8 2.6 1.1 an 1.3 w r These figures, with a range from persalane to dofemane, from 1.5.5 to IV. 1.1. 2, are enough to show the vagueness of the terms gabbro and norite. Although it is difficult to see why B and C should be separated, being placed in different classes, orders, and rangs, the quantitative system brings out the general diversity of character better than the ordinary mineralogical classification. It separates things which, with the exception above noted, are essen- tially distinct. FEMIC ROCKS. From the feldspathic gabbros rocks pass by insensible gradations into varieties which are wholly femic, or nearly so, the pyroxenites, hornblendites, and peridotites. These rocks may contain pyroxene alone, hornblende alone, or olivine alone, or may be mixtures of such minerals. Small quantities of plagioclase may remain as minor impurities; but they count for little in classification. Dunite is nearly pure olivine; saxonite contains enstatite and olivine; picrite is a mixture of augite and olivine. In cortlandtite we have horn- blende and olivine; in wehrlite, diallage and olivine; in Iherzolite, diopside, a rhombic pyroxene, and olivine. Websterite contains bronzite and diopside, and so forms the pyroxenite end of the series. The nomenclature is varied, and the terms are not rigorously used. Hornblendite is a femic rock in which hornblende is the prevailing mineral. 1 The following table deals with the rocks in which pyrox- enes predominate : i Two analyses of hornblendites are given in Washington’s tables, Prof. Paper U. S. Geol. Survey No. 14, 1903, pp. 345, 359. 464 THE DATA OF GEOCHEMISTRY. Analyses of pyroxenites. A. Cortlandtite, Belcher town, Massachusetts. Analysis by L. G. Eakins. Described by B. K. Emer- son. Contains hornblende, pyroxene, biotite, olivine, and magnetite. Magmatic symbol, IV.P.l.l. Belcherose. B. Wehrlite, near Bed Bluff, Montana. Analysis by Eakins. Described by G. P. Merrill. Contains olivine, diallage, brown mica, rarely plagioclase, and secondary iron oxides. Symbol, IV.1 3 .1.2. Wehrlose. C. Hornblende picrite, North Meadow Creek, Montana. Analysis by Eakins. Described by Merrill. Contains hornblende, olivine, pleonaste, iron oxides, and occasionally hypersthene. Symbol, IV.13.1.2. Wehrlose. D. Pyroxenite, Baltimore County, Maryland. Analysis by.J. E. Whitfield. Described by G. H. Williams. Contains hypersthene and diallage. Symbol, V.D.1.1. Maricose. E. Websterite, Webster, North Carolina. Analysis by E. A. Schneider. Described by Williams. Consists of diopside and bronzite. Symbol, V. 11.2.1. Websterose. F. Websterite, Oakwood, Maryland. Analysis by W. F. Hillebrand. Described by A. G. Leonard. Contains hypersthene and diallage. Symbol, V. 11.1.2. Cecilose. G. Lherzolite, Baltimore County, Maryland. Analysis by T. M. Chatard. Described by Williams. Contains olivine, bronzite, and diallage; the olivine partly serpentinized. Symbol, V.l*.l.l. Baltimoriase. H. Pyroxenite, Baltimore County, Maryland. Analysis by Whitfield. Described by Williams. Con- tains hypersthene and diallage. Symbol, V.l 2 . 1.2. Baltimorose. A B C D E F G H Si0 2 48. 63 48. 95 46. 13 51. 94 55. 14 53. 21 43. 87 50. 80 ALOo 5. 32 5. 69 4. 69 2. 53 .66 1. 94 1. 64 3. 40 Fe 9 Oo 2. 91 1. 20 .73 2. 88 3. 48 1. 44 8. 94 1. 39 FeO." 3. 90 12. 11 16. 87 9. 38 4. 73 7. 92 2. 60 8. 11 MgO 21. 79 23. 49 25. 17 25. 97 26. 66 20. 78 27. 32 22. 77 CaO 13. 04 5. 33 4. 41 3. 60 8. 39 13. 12 6. 29 12. 31 ]-Trace. J Na 2 0 .'34 1. 58 .08 None. .30 .11 | .50 K 2 0. .23 } 2.81 .79 } .18 Trace. } 1.38 None. | 2.82 .07 HoO- } .38 . 14 J 1.08 | .52 h 2 o+ .87 7. 64 Ti0 2 .47 .81 .73 None. Trace. .26 .12 None. P 2 0 s . .21 .12 .07 None. .23 Trace. Trace. Trace. C0 2 Trace. .10 s .24 so, .19 Trace. Cl . 16 .24 v 2 o, .03 Cr 2 0, .36 .05 .04 . 60 .25 .20 .44 .32 MnO .12 .08 Trace. Trace. .03 .22 . 19 .17 (Ni,Co)0 .16 .09 .11 .03 Trace: FeS 2 .03 100. 13 100. 54 100. 63 100. 07 100. 36 100. 47 100. 63 100. 03 Norms. A B C D E F G H Q 0.6 1.7 or 1. 1 5.0 0. 6 ab 2. 6 13.6 .5 2.6 1.0 4.2 an 12. 5 5.6 12. 5 6. 7 3.2 2.2 9.2 di 41. 7 16. 5 7. 6 8. 9 32.7 48. 9 22. 6 41.4 hy 21. 9 18. 5 44.8 76.4 57.1 41.4 34. 3 33.8 of. 11.7 37.6 30.4 16. 3 12.2 mt 5.1 1.6 .9 2.8 5.1 2.1 8.4 2.1 hm 3.0 il 1.5 1.2 .5 IGNEOUS ROCKS, 465 The general presence of chromium and nickel in these rocks is noteworthy. The wehrlite (analysis B) is almost on the line between pyroxenites and peridotites. The formation of actual diallage from the normative diopside in it would give the pyroxenes a slight pre- dominance over the olivine. The following analyses represent peridotites : Analyses of 'peridotites. A. Cortlandtite, Ilchester, Maryland. Analysis by W. F. Hillebrand. Described by G. H. Williams. Contains olivine, pyroxene, and hornblende partly altered to talc. Magmatic symbol, IV. I 4 . 1.1. Cort- landtose. B. Peridotite, near Silver Cliff, Colorado. Analysis by L. G. Eakins. Described by W. Cross. Contains hornblende, biotite, hypersthene, olivine, a little plagioclase, apatite, pyrrhotite, and sillimanite. Symbol, IV. I 4 . 1.2. Custer ose. C. Peridotite, near Opin Lake, Michigan. Analysis by Hillebrand. Described by C. It. Van Hise and W. S. Bayley. Contains diallage, olivine, magnetite, and plagioclase. Symbol, IV. 2 3 . 1.2. D. Mica peridotite, Crittenden County , Kentucky. Analysis by Hillebrand. Described by J. S. Differ. Contains biotite, serpentine, and perofskite, with less apatite, muscovite, magnetite, calcite, chlorite, and other secondary products. Symbol, IV.2 4 .1.2. Subrang of Casseliase. E. Saxonite, Douglas County, Oregon. Analysis by F. W. Clarke. Described by J. S. Differ and F. W. Clarke. Contains olivine and enstatite, with a little magnetite and chromite. Symbol, V.l 4 .l.l. F. Dunite, Corundum Hill, North Carolina. Analysis and description by T. M. Chatard. Contains olivine, with a little chromite. Symbol, V.1M.1. Dunose. G. Peridotite, Tulameen River, British Columbia. Analysis by Hillebrand. Described by J. F. Kemp. Contains olivine and serpentine, with magnetite, magnesite, and calcite. Symbol, V.D.l.l. Dunose. A B C D E F G Si0 2 39. 20 46. 03 39. 37 33. 84 41. 43 40. 11 38. 40 A1 2 0 3 4. 60 9.27 4. 47 5. 88 .04 .88 .29 Fe 2 0 3 3. 45 2. 72 4. 96 7.04 2. 52 1. 20 3.42 FeO 6. 15 9. 94 9. 13 5. 16 6. 25 6.09 6. 69 MgO 31. 65 25. 04 26. 53 22. 96 43. 74 48. 58 45. 23 CaO 3.23 3. 53 3. 70 9.46 .55 .35 Na 2 0 .42 1.48 .50 .33 K 2 0 .14 .87 .26 2. 04 } .08 h 2 o - . 50 1 .87 .24 h 2 o+ 9. 38 > . 64 7. 08 | 7. 50 4. 41 2.74 4. 11 Ti0 2 .52 . 66 3. 78 None. 00 2 1. 23 .43 1. 10 P.,0, Trace. . 17 .17 .89 Trace. s!.. .06 Cl .05 Cr 2 0 3 .41 . 68 . 18 . 76 .18 .07 MnO .20 .40 . 12 . 16 None. .24 NiO .30 .21 . 10 . 10 .10 BaO Trace. .06 None. Chromite .56 100. 15 100. 09 99. 94 99. 86 99. 80 100. 34 100. 38 97270°— Bull. 616—16 30 466 THE DATA OF GEOCHEMISTRY. Analyses of peridotites — Continued. Norms. In the peridotites a certain amount of serpentinization is almost always observed. This is shown in the analyses by the unusually large percentages of water. The latter is neglected in calculating the norms, and so normative hypersthene appears, which an absolutely unaltered rock would not show. That is, serpentine, instead of rep- resenting the parent olivine, is equivalent to hypersthene plus olivine, and the norms become misleading. A rock consisting originally of pure olivine might find its place in any one of several different rangs or subrangs, according to the amount of alteration which it has undergone. Two samples from the same rock mass might vary in this manner. Theoretically, no doubt, the quantitative classification applies only to fresh material; practically it is applied to altered peridotites, like those cited above, which all appear in Washington’s tables. A very remarkable peridotite from East Union, Maine, described by E. S. Bastin, 1 contains 22.5 per cent of sulphides, mainly pyrrhotite. Magmatic name, lermondose. BASIC ROCKS. A few igneous rocks exist which seem to form an exceptional group by themselves. They consist largely, or even mainly, of free basic oxides, such as corundum or magnetite; and many transitional mix- tures lie between them and the ordinary silicate rocks. With these oxides it is convenient to group certain titaniferous rocks, which otherwise might form a class by themselves. The following analyses represent a few rocks of this truly basic character, with examples of the transitional forms. 1 Jour. Geology, vol. 16, 1908, p. 124. IGNEOUS BOCKS, 467 Analyses of basic and titaniferous rocks. A. Corundum pegmatite, Ural Mountains, Siberia. Described and analyzed by J. Morozewicz, Min. pet. Mitt., vol. 18, 1898, p. 219. Contains corundum and ortboclase, with accessory rutile, apatite, and zircon. Magmatic symbol, P.5.1.3. Uralose. B. Kyschtymite, Borsowka, Ural Mountains. Described and analyzed by Morozewicz, op. cit., p. 212. Contains corundum, with a little spinel, anorthite, biotite, and zircon. Symbol, I 1 . 5.5. Kyschtymase. C. Umenite norite, Soggendal, Norway. Described and analyzed by C. F. Kolderup, Bergens Museums Aarbog, 1896, p. 165. Contains, in approximate percentages, ilmenite, 37.5; hypersthene, 40.1; anorthite, 11; albite, 8.7; orthoclase, 0.9. Symbol, IV.31.1.3. Bergenose. D. Titaniferous iron ore, Lincoln Pond, Essex County, New York. Analysis by W. F. Hillebrand. Described by J. F. Kemp. Symbol, IV. 4 2 .1.4. Adirondackiase. E. Titaniferous iron ore, Elizabethtown, New York. Analysis by Hillebrand. Described by Kemp. Symbol, IV.4U.4. Champlainiase. F. Magnetite spinellite, Routivaara, Finland. Analyzed and described by W. Petersson, Geol. Foren. Forhandl., vol. 15, p. 49, 1893. Symbol, Y.5 J .1.4. No magmatic name assigned. A B C D E F SiO 40. 06 16. 80 31. 59 11.73 13. 35 4. 08 A1 2 0 3 13. 65 13. 89 8. 54 6.46 8. 75 6. 40 Fe 2 0 3 .35 . 76 24. 52 30. 68 20. 35 33. 43 FeO 2. 36 27. 92 28. 82 34. 58 MgO . 15 . 61 10. 70 3. 35 6. 63 3. 89 CaO . 30 7. 26 2. 25 3. 95 2. 15 . 65 Na 2 0 3. 71 . 38 1. 03 . 50 . 29 K 2 0 5. 20 . 13 . 15 . 26 . 15 H 2 0 .46 . 76 , . 64 1. 68 1. 32 Ti0 2 18. 49 12. 31 16. 45 14. 25 co 2 . 32 . 17 .02 . 82 .02 .02 s. . 04 .09 Cl . 12 Trace. y„o 3 .04 . 61 Cr 2 0 3 .55 . 20 MnO .45 Organic matter .05 Trace. Corundum 35. 40 « 59. 51 99. 28 100. 10 99. 65 99. 19 99. 62 99. 71 a Including a little spinel. Norms. 468 THE DATA OF GEOCHEMISTRY. Analyses of basic and titaniferous rocks — Continued. G. Magnetite basalt, arapahite, North Park, Colorado. Described by H. S. Washington and E. S. Lar- sen, Jour. Washington Acad. Sci., vol. 3, 1913, p. 449. Contains magnetite, bytownite, pyroxene, and a little apatite. Magmatic symbol IV.4(5).1.1. Arapahose. H. Cumberlandite, Cumberland, Rhode Island. Described by B. L. Johnson and C. H. Warren, Am. Jour. Sci., 4th ser., vol. 25, 1906, p. 1. Contains magnetite, ilmenite, plagioclase, olivine, and minor acces- sories. Magmatic symbol V. 3. 1.2. Rhodose. I. Gabbro-nelsonite, Nelson County, Virginia. Contains ilmenite, apatite, hypersthene, plagioclase, some orthoclase, with grains of quartz and pyrite. Magmatic symbol IV.3. 1.2.3. Roselandose. J. Ilmenite-nelsonite, Nelson County, Virginia. Contains ilmenite, apatite, minor hornblende, biotite, leucoxene, etc. Magmatic symbol V.5.5.3.5. Nelsonose. K. Rutile-nelsonite, Nelson County, Virginia. Contains rutile and apatite, with accessory feldspar, ilmenite, and quartz. Magmatic symbol V.5.5.4.5. Virginose. Analyses I, J, K, by W. M. Thornton, jr. Rocks described, with others of similar character, by T. L. Watson in Geol. Survey Virginia, Bull. Ill, A, 1913. L. Perofskite-apatite-magnetite rock, Uncompahgre quadrangle, Colorado. Collected by E. S. Larsen, analyzed by G. Steiger. Not yet fully described. Magmatic symbol V n .53.3.3. Si0 2 .. A1 2 0 3 . FeO. MgO, CaO. H 2 0+. Ti0 2 . . Zr0 2 . . C0 2 . . . S F Cl v 2 o 3 .... Cr 2 0 3 . .. MnO. . . NiO...., (Ni, Co). BaO — SrO.... Zn Cu Pb 19. 74 9. 72 39. 70 15. 60 3. 70 6. 64 .46 ' .66 .32 .04 .58 None. 1. 67 .44 None. .38 None. 99. 65 22. 35 5. 26 14. 05 28. 84 16. 10 1. 17 .44 .10 .42 10. 11 .02 .02 .38 .18 Trace. .43 .08 .71 .08 Trace. 100. 74 .19 100. 55 33. 83 5. 19 11. 38 15. 08 8. 57 8. 22 1. 28 .50 .45 .75 10.00 Trace. 4. 84 .25 .55 .04 .26 101. 19 .30 100. 89 0.70 11. 12 27. 93 .72 8. 34 .15 .58 42. 84 Trace. 6. 89 21 01 .18 99. 67 .08 99. 59 0. 67 2. 87 5.04 .15 12. 16 .09 .11 69. 67 9. 41 .34 . 70 Trace. 101. 21 .39 100. 82 8. 43 .74 19. 16 13. 68 5. 06 19. 98 .35 .59 .35 .65 24. 74 .01 None. 5. 58 .04 .19 None. .20 None. .26 .05 .05 .12 100. 23 .08 100. 15 Less O. IGNEOUS ROCKS. 469 Analyses of basic and titaniferous rocks — Continued. Norms. 1 G 1 H I J K L Q 7. 38 0. 42 or 3. 89 0. 56 2. 78 3. 34 ab 3. 67 3. 67 11. 00 .52 an 22. 24 5. 56 6. 95 ns .61 C. . .10 di. . 1. 51 hy 7. 70 22. 55 1. 10 .40 7. 20 ol 1. 12 45. 70 3. 85 mt 49. 88 20. 65 16. 47 27. 84 hm . . . 5. 28 11. 04 2. 88 il 1. 06 19. 00 19. 15 58. 98 9. 73 11. 25 ru 11. 76 64. 56 . 72 4. 03 11. 42 16. 13 22. 18 13. 10 p?.;;.:::: 30. 74 pr . . . .42 .62 Spinel 3. 55 Sulphides 1. 15 The foregoing table might be much extended, but it is not neces- sary to do so. Other similar rocks are a magnetite syenite porphyry Qcirunose), described by P. Geijer, 1 which contains predominating albite with 38.7 per cent of magnetite and minor accessories. Kra- gerite, from Krageroe, Norway, described by T. L. Watson, 2 con- sists largely of plagioclase feldspars with 25 per cent of rutile. The Canadian urbainite 3 is essentially a mixture of ilmenite, hematite, and rutile, with only a few per cent of other minerals. The New York (Adirondack) ores, 4 of which analyses are given above, are found in close association with norites or gabbros. Rocks of this class could hardly be associated with persilicic masses, such as gran- ites or syenites. They represent a marked deficiency of silica in the magmas from which they came. LIMITING CONDITIONS. Although the igneous rocks, as the analyses and descriptions show, represent a great variety of mineral mixtures, their proximate con- stitution is subject to distinct limitations. In the preceding chapter upon rock-forming minerals some of these limitations were indicated, and it was shown that certain species can appear only under certain 1 Geol. Kiruna district, Stockholm, 1910, p. 60. 2 Am. Jour. Sci., 4th ser., vol. 34, 1912, p. 509. 8 See C. H. Warren, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 263. * Recent memoirs on the Adirondack ores are by J. F. Kemp, Nineteenth Aim. Rept. U. S. Geol. Sur- vey, pt. 3, 1899, p. 383; and Bulls. New York State Museum No. 119, 1908; No. 138, 1910. Also D. H. New- land, Econ. Geology, vol. 2, p. 763. An important paper on the Scandinavian ores, by H. Sjogren, is in Trans. Am. Inst. Min. Eng., vol. 37, 1907, p. 809. On the titaniferous iron ores of the United States, see J. T. Singerwald, Bull. U. S. Bureau of Mines No. 64, 1913. 470 THE DATA OF GEOCHEMISTRY. definite conditions. The experiments of Morozewicz upon the sepa- ration of corundum, iolite, etc., from magmas are cases in point. It may be well, however, to reiterate some of the observations which have already been made or suggested in order to- properly emphasize these important considerations. For this purpose we need only take into account the more conspicuous magmatic minerals, and neglect the rarer species. Since nearly all igneous rocks are formed chiefly of silicates, a partial table of rock-forming minerals, arranged by bases with refer- ence to maximum and minimum silica, will be convenient. The minerals to be thus considered are the following: Rock-forming minerals. Base. Maximum silica. Minimum silica. Potassium Sodium Calcium Magnesium Ferrous iron Ferric iron Aluminum Orthoclase, KAlSi 3 0 8 Albite, NaAlSi 3 0 8 Diopside, CaMgSi 2 0 6 Enstatite, MgSi0 3 Pyroxene, FeSi0 3 Acmite, FeNaSi 9 0 6 Albite, NaAlSi 3 0 8 Leucite, KAlSi 2 0 6 . Nephelite, NaAlSi0 4 . Anorthite, CaAl 2 Si 2 0 8 .a. Forsterite, Mg 2 Si0 4 \ ni - . ^ Fayalite, Fe|i0 4 | 0Uvlne - Magnetite, Fe 3 0 4 . Corundum, A1 2 0 3 . a Melilite, a basic silicate, is here left purposely out of account, and so, too, is &kermanite. Intermediate minerals, such as analcite, biotite, muscovite, etc., that contain water can form only under pressures or conditions of viscosity which prevent the water from expulsion. The two oxides in the foregoing list can only appear in notable amounts when the iron or alumina is largely in excess of the silica. The latter will go to the formation of silicates until it is saturated, and after that any superfluous oxide can be deposited. This state- ment, however, demands qualification. Free silica and magnetite can coexist in igneous rocks to a very limited extent, but not as prin- cipal constituents. The conditions of their coexistence are uncertain, but are possibly due to dissociation in the molten magma. It is con- ceivable that the latter may solidify under circumstances of viscosity which prevent some of the separated ions from uniting, so that a little quartz and a little magnetite may be present, side by side, in the same rock. This explanation, however, is merely speculative and requires proof. The exception does not invalidate the broad general state- ment that the two species are essentially incompatible. Much mag- netite and much quartz do not occur together in rocks of igneous origin. Similar incompatibilities are shown elsewhere in the table. Leucite and silica will form orthoclase; nephelite and silica yield albite; a member of the olivine family with silica will be converted into IGNEOUS ROCKS. 471 pyroxene, and so on. With an excess of silica over that required to generate compounds which appear in the minimum column higher silicates will he produced, and as silica is abundant in the lithosphere the maximum is most often reached. Feldspars and pyroxenes are much more common than lenad minerals or olivine. The occasional concurrence of quartz and olivine in some basalts and gabbros may perhaps be due to the same dissociation as that suggested by the coexistence of quartz and magnetite. The general tendency in a cool- ing magma is toward the generation of saturated compounds. When silica exceeds the amount which can be taken up by the bases the excess appears as quartz, tridymite, or opal, or else it becomes an undifferentiated portion of a residual glass. With adequate silica, then, the number of compounds which a magma can yield is small. The persilicic rocks, therefore, are rela- tively simple in their mineralogical constitution, and in the quanti- tative classification their modes do not differ very greatly from their norms, except with respect to the micas, hornblendes, and augite. But as silica diminishes in amount the mineralogical complexity of a rock is likely to increase, for the reason that a larger range of unions has become possible. For each base a number of compounds are capable of formation, and the same magma, solidifying under different conditions, may yield very dissimilar products. In other words, we encounter the well-known fact that two rocks may have the same ultimate composition and yet contain different mineral species. The difficulty of apportioning the several bases to the sev- eral minerals in a rock is familiar to everyone who has tried to discuss any large number of rock analyses. Potassium may form orthoclase, leucite, muscovite, or biotite; sodium may yield albite, nephelite, analcite, alkali hornblende, or acmite; calcium appears in pyroxene, amphibole, anorthite, or melilite; magnesium in pyroxene, amphibole, olivine, or biotite; iron in pyroxene, amphibole, olivine, acmite, magnetite, or ilmenite; and aluminum in feldspars, lenads, micas, amphibole, pyroxenes, or corundum. The conditions of equi- librium have become exceedingly complicated, and it is only as we approach the subsilicic magmas that simplicity is again restored. With deficient silica the number of possibilities is lessened and such simple rocks as the peridotites and pyroxenites are formed. An intermediate magma may be simple from lack of certain constitu- ents, but cases of that kind are exceptional. The mediosilicic rocks are as a rule more complex mineralogically than the persilicic or subsilicic extremes. The ends of the petrographic series, free silica, or free basic oxides, are necessarily the simplest rocks of all. At one end we have segregations of quartz; at the other, corundum rocks or magnetite. Bocks midway between these extremes, with silica ranging from 45 to 55 per cent, contain the greatest variety of 472 THE DATA OF GEOCHEMISTRY. minerals, for ortho-, meta-, and tri-silicates are then capable of coexistence. In a rock containing silicates of all three classes, with alumina, lime, magnesia, the two alkalies, and both oxides of iron as bases, the possibilities of union become very numerous. In the magma itself the bases will be apportioned to the several silicic acids in accordance with the law of mass action, each one being gov- erned by the relative number of its molecules in a unit volume of solution. When cooling begins, the separation of each mineral will depend upon its fusibility, its solubility, and its relation to the possible eutectic ratios; and the solubility will fluctuate with changes in the temperature of the mass. With each deposition of crystals all of the foregoing conditions will change, for the composition of the residual fluid will have been altered. In theory, then, the physical and chemical conditions of solidification are most complex, except for two-component and possibly three-component systems. We are therefore compelled to deal with the problem of rock composition empirically and to make use of rules based upon direct observation. These rules are by no means rigorous, for although the separation of minerals from a cooling magma generally follows a stated order that order often varies. In most cases it is the order described by H. Rosenbusch , 1 as follows: 1. Apatite, zircon, spinel, the titanates, and iron ores. These are almost invariably the first minerals to crystallize. 2. The Mg-Fe, Mg-Ca, and Fe-Ca silicates, such as olivine, amphibole, and py- roxene. Biotite is also placed in this class. As a rule the orthosilicates precede the metasilicates; olivine, for example, separating before pyroxene. 3. Feldspars and lenads in the order anorthite, plagioclase, alkali feldspars, nephe- lite, leucite. 4. Any excess of quartz. The frequency with which this order is followed is probably a consequence of the fact that most rocks consist mainly of alumo- silicates, and especially of feldspars and quartz. That is, they con- tain predominantly compounds of the same class, in which the other rock-forming minerals are dissolved. The latter separate from solu- tion in the general order of their solubility, the least soluble first; but that property varies with the composition of the mixture. In an isomorphous series, like the feldspars, the least fusible tend to be deposited earlier than the others, but fusibility is a minor factor in the process of solidification. Quartz, which solidifies in most cases at the very end of the series, is a relatively infusible substance; but, as we have already seen, it probably forms a eutectic mixture with the feldspars which, by virtue of its depressed melting point, is the last part of a magma to congeal. The minor accessories among the rock-forming minerals, which crystallize first, although present in trifling amounts, possibly form no eutectics with the feldspars. Otherwise we should expect them to remain in solution much longer. 1 Elemente der Gesteinslehre, 1898, p. 40. Igneous rocks. 473 PROXIMATE CALCULATIONS. It is clear, from what has been already said, that it is rarely pos- sible to predict, with anything like quantitative accuracy, what minerals will form when a magma of given composition solidifies. Partial and semiquantitative forecasts are practicable; we can say, for instance, that the proportion of orthoclase will lie between assignable limits; and if the analysis shows a ratio of silicon to oxygen lower than Si 3 0 8 , or 1 : 2.667, we may be reasonably sure that a calculable amount of silica will remain uncombined. Only in the simplest cases can a complete forecast be made, and they are exceptional. Suppose, however, that instead of a magma or an analysis repre- senting a magma and nothing more, we attempt to discuss the com- position of a rock in which the separate minerals have been identified by the microscope. In other words, suppose we have the bulk analysis of a rock and also its petrographic description, how far can we compute its proximate composition? To this question no single answer can be given; in some cases the computation is easy, in others it is impossible. The conventional “ norms ’ ’ of the quantitative classification can always be calculated, but the actual composition may be quite another thing. It is the latter which concerns us now. Let us take some concrete examples for discussion. Two rocks of relatively simple composition are the following, for which data are-given in the Survey Bulletin 591, and also in Washing- ton’s tables. A. Granite-syenite porphyry, Little Rocky Mountains, Montana. Analysis by H. N. Stokes. Described by W. H. Weed and L. V. Pirsson. Contains orthoclase, quartz, oligoclase, muscovite, and iron oxides. Liparose. B. Biotite granite, El Capitan, Yosemite Valley. Analysis by W. Valentine. Described by H. W. Turner. Contains alkali feldspar, plagioclase, quartz, biotite, titanite, apatite, and iron oxides. The analysis shows that a trace of zircon is probably present also. Toscanose. Analyses. Norms. A B Si0 2 68. 65 71. 08 A1 2 0 3 18.31 15. 90 Fe 2 0 3 .56 .62 FeO .08 1. 31 MnO . 15 MgO .12 .54 CaO 1. 00 2. 60 SrO .10 .02 BaO .13 .04 Na 2 0 4. 86 3. 54 K 2 0 4. 74 4. 08 H 2 0- . 27 h 2 0+ .83 .30 Ti0 2 .20 .22 Zr0 2 .08 P„0* . 10 Cl .03 .02 99. 88 100. 60 A B Q 20.2 27.8 or 27.8 23.9 ab 40.9 29.9 an 5.0 k 13. 1 C 3.5 .9 hy .3 3.3 mt .2 .9 hm .4 474 THE DATA OE GEOCHEMISTRY. In calculating the actual composition of these rocks, it is best to first eliminate the accessories. Zr0 2 is calculated as zircon, Fe 2 0 3 as hematite or magnetite, P 2 0 5 and Cl as apatite, and Ti0 2 as ilmenite, titanite, or rutile, according to the indications given in the petro- graphic descriptions. All remaining CaO is then reckoned as equiv- alent to anorthite, and all Na 2 0 as albite. In A the trivial amount of MgO is assumed to be in the form MgSi0 3 , that is, as pyroxene or amphibole; in B the magnesia and remaining iron oxide are to be computed as biotite, with the normal formula Al 2 (MgFe) 2 KHSi 3 0 12 . Upon comparing K 2 0 with the remainder of the A1 2 0 3 , the latter, in A, is found to be in excess of the amount required for orthoclase. That excess gives a datum for the calculation of muscovite; and when that is deducted, only quartz and orthoclase remain to be con- sidered. The orthoclase is given by the K 2 0 and A1 2 0 3 still unap- propriated, and the remaining free silica represents the quartz. The results of the computation are shown below, the trifling amount of MnO being consolidated with FeO, and the SrO and BaO with lime. A little water is left unaccounted for, presumably as uncombined with any silicate. Calculated composition of rocks represented in preceding table. A B Quartz ; 19. 98 29. 64 Orthoclase 18. 90 19. 74 Albite 41. 07 29. 87 Anorthite 5. 41 12.23 Muscovite 13. 06 Biotite 6. 50 MgSiO, .30 Zircon . 12 Titanite .54 Apatite .24 Ilmenite . 17 Rutile .11 Magnetite .93 Hematite .56 99. 56 99. 81 These calculations are simple enough, and the results are fairly accurate. The chief uncertainties are with the micas, and especially with the biotite in B, for rock-forming biotite is a mineral of variable composition, and their errors affect the computations with regard to orthoclase and quartz. A comparison of the last table with that of the norms will show how far the two methods of calculation diverge. Suppose, however, that we are called upon to discuss the composi- tion of a rock containing orthoclase, plagioclase, biotite, augite, oli- vine, and magnetite, with the femic minerals present in fairly large IGNEOUS ROCKS. 475 proportions. In such, a case the alumina goes to form five of the com- ponent minerals, iron to four, lime to two, magnesia to three, and potassium to two. We now need more data than the bulk analysis and the usual petrographic description can give us, and the required information may be obtained either from chemical or from physical sources. Chemically, we may separate the biotite, augite, and olivine from the rock and analyze each one by itself. In that way we can learn something of the distribution of the bases, and so become able to calculate the composition of the rock. Or, olivine being soluble in very dilute acids, we may dissolve it out from a known weight of rock and determine the amount of iron and magnesia which belong to it. The same procedure may be followed for the determination of nephelite when that mineral happens to he present. Physically, the rock may be studied in thin sections under the microscope, when the areas occupied by the several minerals can be measured with a micrometer. Given a sufficient number of such measurements, and, the densities of the minerals being known, the relative proportion of the elements may be calculated, and the results obtained can be checked by the chemical analysis . 1 A cruder process consists in taking an enlarged photomicrograph of the thin section, cutting the areas representing the minerals out of the paper, and then, by weigh- ing the latter, ascertaining their relative proportions. In some cases a rock powder, in known quantity, can be mechanically separated into its mineral constituents by means of Thoulet’s or other heavy solu- tions, and the individual portions so determined directly. By one method or another the problem of mineral composition can generally be solved. Only when a rock contains much glass or other inde- terminate matter is the problem incapable of fairly accurate solution. If alteration products are present — chlorites, zeolites, kaolin, limonite, etc. — the discussion of modes becomes very unsatisfactory, and the conclusions which are then reached have very slender value. Note. — The composition of igneous rocks is often represented graphically by means of diagrams, and several methods for doing this have been devised. For an exhaustive memoir upon this subject see J. P. Iddings, Prof. Paper U. S. Geol. Survey No. 18, 1903. The diagrams are of considerable service to the petrographer, for they bring chemical relationships and differences vividly before the eye. The triangular diagrams of Osann, Min. pet. Mitt., vol. 19, 1900, p. 351, are much used. See also papers by F. Becke, idem, vol. 22, 1903, p. 209; L. Finckh, Monatsh. Deutsch. geol. Gesell., 1910, p. 285; and B. G. Escher, Centralbl. Min., Geol. u. Pal., 1911, pp. 133, 166. 1 This method is fully discussed in the Quantitative classification, pt. 3, pp. 186-230, together with the subject of calculating norms and modes. According to Ira A. Williams, however (Am. Geologist, vol. 35, 1905, p. 34), the micrometer method is unsatisfactory. See also A. Rosiwal, Verhandl. K.-k. geol. Reichs- anstalt, 1898, p. 143. CHAPTER XII. THE DECOMPOSITION OF ROCKS. THE GENERAL PROCESS. When a rock is exposed to atmospheric agencies it undergoes a partial decomposition and becomes gradually disintegrated. Some of its substance is dissolved by percolating waters, themselves of atmospheric origin, and is so carried away; the remaining material, partly hydrated and partly unchanged in composition, contains products which are easily separable from one another. By flowing streams the finer clays or silts are taken away from the coarser and heavier sand grains, and this process is an important step toward the ultimate formation of sandstones and shales. Solution, hydration, disintegration, and mechanical sorting are the successive stages of rock decomposition. I speak now in general terms. The subsidiary agents of decomposition will be considered in their proper connection later. The breaking down of a rock is effected partly by mechanical and partly by chemical means. Mechanical agencies, such as the grind- ing power of glaciers, the pounding of waves, erosion by streams, the disruptive effects of frost, or the action of wind-blown sand, tend to separate the particles of a rock and to furnish fresh surfaces to chem- ical attack. Unequal expansion, due to alternations of heat and cold, also assist in producing disintegration . 1 The distribution of volcanic dust is still another mode by which finely subdivided rock is ren- dered available for aqueous decomposition. The latter depends for its efficiency partly upon the water itself and partly upon dissolved acids, salts, or gases. Rain water falls upon the surface of a rock and sinks more or less deeply into its pores and crevices. Rain, as we have already seen , 2 carries oxygen and carbon dioxide in solu- tion, together with other substances in varying proportions. Water and gas both exert a solvent action, and the fluid which then satu- rates the rock becomes charged with the products of solution. These may intensify or inhibit further action, according to circumstances. Some of the dissolved matter, redeposited, may form a protecting film and so delay or prevent further solution. This retardation, however, is temporary, for mechanical disintegration is accompanied 1 This subject is fully discussed by J. C. Branuer, in his paper upon the decomposition of rocks in Brazil, Bull. Geol. Soc. America, vol. 7, 1896, p. 255. 2 See ante, p. 49 et seq. 476 THE DECOMPOSITION OF ROCKS. 477 by a rubbing of the loosened particles together, and so the coating of insoluble matter is removed. Normal air contains, in round numbers, 21 per cent by volume of oxygen and 0.03 of carbon dioxide. In rain water these active gases are concentrated, as shown by the analyses of R. W. Bunsen. 1 • Air extracted from rain water at different temperatures has the compo- sition by volume given below. Composition of air extracted from rain water at different temperatures. 0° 5° 10° 15° 20° Carbon dioxide 2. 92 2. 68 2. 46 2. 26 2. 14 Oxygen 33. 88 33. 97 34. 05 34. 12 34. 17 Nitrogen a 63. 20 63. 35 63. 49 63. 62 63. 69 100. 00 100. 00 100. 00 100. 00 100. 00 a Including argon. As waters of this character sink deeper into a rock mass, a portion of their effectiveness is lost, for oxygen and carbon dioxide are chiefly consumed near the surface, and their share of the chemical effect tends to become zero. The decrease in the case of oxygen is clearly shown by the experiments of B. Lepsius, 2 who has analyzed the gase- ous contents of waters from three bore holes of different depth. Air extracted from water at 12 meters below the surface contained 24.06 per cent of oxygen, at 18 meters, 21.97 per cent, and at 25 meters, only 12.90 per cent. In rock decomposition, then, oxidation is largely a surface phenomenon, and the action of carbon dioxide, so far as it is directly obtained from the atmosphere, must follow the same rule. Carbonic acid, however, is also derived from other sources, so that its effects are not necessarily limited to the upper strata. Its presence in ground waters will be considered presently. 3 When meteoric waters act upon a mass of rock, the effects produced will depend upon the nature of the minerals which they encounter. Let us confine our attention for the moment to the more important species of magmatic origin, such as the feldspars, micas, pyroxenes, amphiboles, olivine, leucite, nephelite, and the typical sulphide, pyrite. The last-named mineral, although found in relatively small proportions, is nevertheless important, for by oxidation and hydra- tion it yields solutions of sulphates having a distinctly acid reaction. These acid solutions act strongly upon other constituents of rocks, and intensify the activity of the percolating waters. The sulphates 1 Ann. Chem. Pharm., vol. 93, 1855, p. 48. See also M. Baumert, idem, vol. 88, 1853, p. 17. 2 Ber. Deutsch. chem. Gesell., vol. 18, 1885, p. 2487. Evidence of s imil ar purport has been recorded by other observers. * W. G. Levison, Annals New York Acad. Sci., vol. 19, 1909, p. 121, suggests that the oxygen liberated by aquatic plants may assist in the decomposition of rock material. 478 THE DATA OF GEOCHEMISTRY. contained in natural waters are largely derived from this source, at least primarily. The re-solution of secondary sulphates is of course not to be overlooked, but it is obviously a later phenomenon. SOLUBILITY OF MINERALS. That nearly all minerals are more or less attacked by water has long been known, and also that carbonated waters act still more ener- getically. The experiments of W. B. and It. E. Rogers, 1 in 1848, established these facts conclusively. Many minerals were tested, and all were perceptibly soluble. From 40 grains of hornblende, digested during forty-eight hours in water charged with carbonic acid, 0.08 grain of silica, 0.095 of ferric oxide, 0.13 of lime, and 0.095 of mag- nesia, or nearly 1 per cent in all, were extracted. 2 In the classical investigations of A. Daubree 3 3 kilograms of orthoclase, agitated with pure water for 192 hours in a revolving iron cylinder, yielded a solution containing 2.52 grams of K 2 0, with trifling amounts of silica and alumina. Two kilograms of the feldspar, shaken for ten days in water saturated with carbon dioxide, gave 0.270 gram of K 2 0 with 0.750 of silica. A 3 per cent solution of sodium chloride was a much less effective agent than water alone. Leucite was not so vigorously attacked as orthoclase. In 1867 A. Kenngott 4 showed that many minerals gave an alka- line reaction when in contact with moistened test paper; and in 1877 R. Muller 5 published an important memoir upon the solu- bility of various species in carbonated water. The powdered sub- stances were digested in the solvent during seven weeks, and after that treatment the dissolved portions were quantitatively analyzed. The results are summed up below. The percentages of the several constituents determined refer to the total amount of each in a given mineral; the “sum” is the percentage of all dissolved matter in terms of the original substance. That is, under K 2 0 1.3527 per cent of the total potash in orthoclase was dissolved, while only 0.328 per cent of the entire mineral passed into solution. 1 Am. Jour. Sci., 2d ser., vol. 5, 1848, p. 401. 2 The temperature at which the experiment was conducted.was 60°, presumably Fahrenheit. 3 Etudes synthetiques de g6ologie experimental, pp. 271-275. See also p. 252 for an experiment upon the solubility of granite. * Neues Jahrb., 1867, pp. 77, 769. 5 Jahrb. K.-k. geol. Reichsanstalt, vol. 27, Min. Mitt., 1877, p. 25. Muller gives a good summary of previ- ous work upon the subject, and cites, in addition to the memoirs mentioned here, papers by Dittrich, Haushofer, Ludwig, Hoppe-Seyler, and others. A later summary, by F. K. Cameron and J. M. Bell, is in Bull. No. 30, Bureau of Soils, U. S. Dept. Agric., 1905, p. 12. P. Pichard (Annales chim. phys., 5th ser., vol. 15, 1878, p. 529) found that several magnesian silicates gave alkaline reactions with litmus paper. F. Sestini (abstract in Zeitschr. Kryst. Min., vol. 35, 1902, p. 511) made similar but quantitative observations on augite, amphibole, and tremolite. According to F. Cornu (Min. pet. Mitt., vol. 24, 1905, p. 417; vol. 25, 1907, p. 489), who tested many minerals with litmus, kaolinite, pyrophyllite, nontronite, etc., give acid reactions. THE DECOMPOSITION OF ROCKS. 479 Material extracted from minerals by carbonated water. Si0 2 . A1 2 0 3 . K 2 o. Na 2 0. MgO. CaO. P 2 0 6 . FeO. Sum. Adularia. . . Oligoclase.. Hornblende 0. 1552 0. 1368 1. 3527 Trace. 0. 328 . 237 9. 1713 2. 367 3. 213 Trace. .533 .419 Trace. Trace. 8. 528 4. 829 1. 536 Magnetite. . .942 .307 Do. ... Trace. 2. 428 1. 821 A patite 1. 696 1. 417 1. 529 Do. . . . 2. 168 1. 822 2. 018 Do 1. 946 2. 12 Trace. 1. 976 Olivine .... .873 Trace. 1. 291 8. 733 2. Ill Serpentine. .354 2. 649 1. 527 1. 211 The relative solubility of several minerals, chiefly magnesian species, in ordinary water was determined by E. W. Hoffmann 1 in 1882. His method of procedure consisted in allowing water to per- colate through the powdered material for two months and measur- ing the loss of weight; a possibility of gain by hydration seems not to have been considered. The data given are as follows: Relative solubility of various minerals in water. Grams taken. Loss of weight. Vesuvianite 4. 109 0. 064 Epidote 3. 353 .052 Olivine 3. 506 .078 Chlorite 2. 591 . 094 Talc 1. 1245 . 105 Muscovite .5058 .056 Biotite .9736 .035 The excessive solubility here shown for talc and muscovite is highly questionable. Hoffmann’s experiments are entitled to very little weight. It has been shown by Alexander Johnstone 2 that micas exposed to the action of pure and carbonated waters during an entire year became hydrated and increased in volume. The latter phe- nomenon may account for the easy weathering of micaceous sand- stones. Muscovite appeared to be insoluble, but in a solution of car- bonic acid the biotite lost magnesia and iron. In another communi- cation 3 Johnstone states that olivine is slightly attacked by carbo- nated water; and in still another 4 he described the action of that reagent upon orthoclase, oligoclase, labradorite, hornblende, augite, etc. Among the feldspars, orthoclase was the least and labradorite 1 Inaug. Diss., Leipzig, 1882. 2 Quart. Jour. Geol. Soc., vol. 45, 1889, p. 363. 3 Proc. Roy. Soc. Edinburgh, vol. 15, 1888, p. 436. * Trans. Edinburgh Geol. Soc., vol. 5, 1887, p. 282. 480 THE DATA OP GEOCHEMISTRY. the most soluble; hornblende and augite were acted upon even more rapidly. These observations seem to be in harmony with those of Muller, whose figures show a similar order of magnitude among the determined solubilities. In recent years a few data have been published by C. Doelter 1 rela- tive to anorthite, nephelite, and some zeolites. The nephelite in par- ticular was strongly attacked by carbonic acid. There are also ex- periments by F. W. Clarke 2 on the alkalinity of several silicates, which were followed by some quantitative determinations b.y G. Steiger . 3 Micas, feldspars, leucite, nephelite, cancrinite, sodalite, spodumene, scapolite, and a number of zeolites were studied, and in every case a distinct solubility was observed. Apophyllite, natrolite, and pectolite gave remarkably strong alkaline reactions when mois- tened, but the intensity of the coloration produced with indicators gave inaccurate information as to the extent to which decomposition had occurred. Between the qualitative and the quantitative data there were discrepancies, which have been cleared up only within the last few years. A. S. Cushman , 4 in his work upon rock powders, has shown that when orthoclase is shaken with water an immediate ex- traction of alkaline salts takes place, but it is only a partial measure of the amount of decomposition. Colloidal substances, silica or alumi- nous silicates, are formed at the same time, which retain a portion of the separated alkali, but give it up to electrolytic solvents. For example, 25 grams of orthoclase were shaken up with 100 cubic centi- meters of distilled water. The mixture was filtered, and the filtrate on evaporation gave 0.0060 gram of residue. With a 2 per cent solu- tion of ammonium chloride a soluble residue of 0.0608 gram was obtained. With diabase 25 grams in pure water yielded an extract of 0.0064 solid residue; with a 1 per cent solution of ammonium chloride it gave 0.1412 gram. These gains do not imply increased decomposition, but only a liberation of the soluble compounds which had been entangled in the colloids that were formed at the same time. Any salt in solution is likely to affect in some such manner the appa- rent solubility of a rock or mineral, a conclusion which is in harmony- with many observations upon the tendency of soils and clays to absorb salts, and especially salts of potassium, from percolating waters. As the latter change in composition, their decomposing and dissolving 1 Min. pet. Mitt., vol. 11, 1890, p. 319. 2 Bull. U. S. Geol. Survey No. 167, 1900, p. 156. 8 Idem, p. 159. Z. 44 > 4 . zy MgO .38 . 73 1. 92 1. 43 7. 80 7. 05 .50 .07 CaO .85 .93 1. 22 .95 15. 65 11. 83 .72 1. 58 Na 2 0 2. 19 .80 1. 33 1. 45 .84 .92 .66 1. 06 K 2 0 1. 61 .93 1. 60 .83 2. 36 2. 60 2. 08 2. 64 H 2 0 4. 63 10. 46 11. 72 10. 79 1. 95 2. 02 a 4 . 11 a 3. 21 Ti0 2 .45 .28 . 13 . 16 .35 .45 p 2 o 5 .02 .03 .04 *03 .05 .13 . 14 .07 MnO .04 .01 .06 .03 Trace. .03 . 17 C0 2 .43 . 30 . 39 .29 18. 76 15. 47 Organic C . 19 . 34 1. 09 .22 . 32 . 38 so 3 . 13 .05 Cl . 06 .04 100. 39 100. 50 100. 68 100. 09 100. 27 100. 50 99. 84 100. 20 « Loss on ignition. Must include CO 2 and organic matter. 1 Sixth Ann. Rept. U. S. Geol. Survey, 1885, pp. 249-250. According to S. Weidman (private communi- cation) the clay from Dodgeville is really loessial, and the two from Milwaukee are lacustrine. Accurate diagnosis appears to be difficult. 2 Trans. Edinburgh Geol. Soc., vol. 8, 1901, p. 60. 508 THE DATA OF GEOCHEMISTRY. In the two Wisconsin clays the carbonates represent magnesian limestone. The Scottish clays had evidently a different parentage. Glacial clays often contain carbonates, which are rarely conspicuous in rock residues . 1 Even residual soils derived from the decay of limestones are practically free from carbonates, as the subjoined analyses show. The residues are merely clay or silt entangled with the limestone when the latter was laid down and released by its solution. Analyses of residual clays. A. Residual clay from so-called Trenton limestone, Lexington, Virginia. Analysis by R. B. Riggs. Described by I. C. Russell, Bull. U. S. Geol. Survey No. 52, 1889. Russell especially discusses the cause of red coloration in clays. On this subject see also W. O. Crosby, Am. Geologist, vol. 8, 1891, p. 72; and W. Spring, Rec. trav. chim., vol. 17, 1898, p. 202. B. Residual clay from limestone, Staunton, Virginia. Analysis by George Steiger, U. S. Geol. Survey. C. Residual clay from Knox dolomite, Morrisville, Alabama. Analysis by W. F. Hillebrand. Described by Russell, op. cit. A B c Si0 2 43. 07 55. 90 55. 42 A1 2 0 3 25. 07 19. 92 22. 17 Fe 9 0q 15.16 7. 30 8. 30 FeO .39 Trace. MgO .03 1. 18 1. 45 CaO . 63 . 50 . 15 Na 2 0 „ 1. 20 .23 . 17 K 2 0 2. 50 } 12. 98 4. 79 2. 32 H 2 0- 2. 54 2. 10 h 2 o+ 6. 52 7. 76 Ti0 2 J .20 P 2 0, . 10 C0 2 .38 100. 64 99. 95 99.84 i Innumerable analyses of clays and soils have been made for agricultural and other industrial purposes Several States have issued special reports upon their clay industries. Among the reports of geological surveys are those of Connecticut, Bull. No. 4, 1905, G. F. Loughlin; New Jersey, 1878, G. H. Cook; New Jersey, vol. 6, 1904, H. Ries and H. B. Kummel; Maryland, vol. 4, pp. 203-503, Ries; Virginia, Bdll. No. 11, 1906, Ries; West Virginia, vol. 3, 1905, G. P. Grimsley; South Carolina, Bull. No. 1, 4th ser., 1904, E. Sloan; Georgia, Bull. No. 6 A, 1898, G. E. Ladd; Alabama, Bull. No. 6, 1900, Ries; Wisconsin, Bull. No. 7, 1901, E. R. Buckley; Missouri, vol. 11, 1896, H. A. Wheeler; Indiana, Twenty-ninth Ann. Rept., 1905, W. S. Blatchley; Iowa, vol. 14, 1904, S. W. Beyer and I. A. Williams; Wisconsin, Bull. No. 15, 1906, Ries. See also the volumes on chemical analyses published by the geological surveys of Pennsylvania and Ken- tucky; Bull. New York State Mus., vol. 3, No. 12, 1895, Ries; and Bull. U. S. Geol. Survey No. 228, pp. 351-370. Ries, Sixteenth Ann. Rept. U. S. Geol. Survey, 1895, pp. 554-574, gives a long table of analyses of American clays, and a general report by Ries forms Prof. Paper 11 of the Survey, 1903. Bull. U. S. Geol. Survey No. 143, 1896, by J. C. Branner, is a bibliography of clays and ceramics. The American Ceramic Society has since (1906) published a more elaborate bibliography by the same author. Geology of North Carolina, vol. 1, 1875, contains much material on soils, and so, too, do the volumes on cotton pro- duction published by the Tenth U. S. Census. The literature regarding soils is too voluminous to admit of any summary here. Recent papers of interest are those by N. Sibirtzew, Compt. rend. VII Cong, intemat. geol., 1897, p. 73, on the soils of Russia, and by W. Frear and C. P. Beistle, Jour. Am. Chem. Soc., vol. 25, 1903, p. 5. Work by Schlosing and Van Bemmelen on tropical soils has already been cited. W. Maxwell (Lavas and soils of the Hawaiian Islands, Honolulu, 1898) and A. B. Lyons (Am. Jour. Sci., 4th ser., vol. 2, 1896, p. 421) have also contributed to this phase of the subject. On the constitution of arable soils see L. Cayeux, Ann . Soc. g6ol? du Nord, vol. 34, 1905, p. 146. On the origin and nature of soils see N. S. Shaler, Twelfth Ann . Rept. U. S. Geol. Survey, pt. 1, 1891, p. 219. On fuller’s earth see T. W. Vaughan, Bull. U. S. Geol. Survey No. 213, 1903, p. 392, and J. T. Porter, Bull. No. 315, 1907, p. 268. On soils in general see E. W. Hilgard’s treatise “Soils,” published in 1906. THE DECOMPOSITION OF ROCKS. 509 LOESS. In its chemical composition, the widespread earthy deposit known as loess closely resembles the glacial clays. It commonly, but not invariably, contains much calcium carbonate, and the same is true of the related or perhaps identical adobe soil of the more arid regions in our Western States. The more striking peculiarities of the loess are its light color, its extremely fine state of subdivision, the angular- ity of its particles, its lack of stratification, its coherence, and its porosity. Furthermore, the fossils found in loess are almost without exception the remains of land animals, which indicate that it can not be a deposit from permanent waters. Over the origin of loess there has been much controversy, but the subject is one that admits of only the briefest summary here. The prevalent view is essentially that of F. Richthofen , 1 who interprets the loess of China as an eolian formation. In the arid regions of central Asia the products of rock disintegration are sorted by the winds, and the finest blown dust finally comes to rest where it is entangled and protected by the grasses of the steppes. Temporary streams, formed by torrential rains, assist in its concentration and bring about accumulations of loess in valleys and other depressions of the land. According to I. C. Russell , 2 the adobe of the Great Basin is formed essentially in this way, and the sediments deposited in the so-called “playa” lakes, whose beds are dry during a great portion of the year, consist of this material. The adobe contains the finer products formed by subaerial erosion of the mountain slopes, and may be commingled sometimes with dust of volcanic origin. The loess of the Missouri and upper Mississippi valleys is given nearly the same interpretation by C. R. Keyes , 3 only in this case the dust is formed from river silt left on the dried mud banks in times of low water. The loess of Iowa is regarded by W J McGee 4 as a glacial silt, deposited along the margins of glaciers during the glacial period. W. F. Hume , 5 studying the Russian loess, described that also as glacial silt, distributed partly by winds and partly by floods. C. Davison 6 considers loess to be a product of glacial erosion, accumu- lated first in banks of snow and concentrated later in the valleys 1 China, vol. 1, p. 74; Geol. Mag., 1882, p. 297. See also R. Pumpelly, Am. Jour. Sci., 3d ser., vol. 17, 1879, p. 133. For analyses of Chinese loess see A. Schwager, Geognost. Jahreshefte, 1894, p. 87. For German loess, H. G. Schering, Inaug. Diss., Freiburg, 1909. For South American loess, E. H. Ducloux, Rev. Museo de la Plata, vol. 15, 1908, p. 162. The loess of Argentina has been studied by P. Werling, Inaug. Diss., Freiburg, 1911. Other analyses of loess are to be found in the older treatises of Bischof and Roth. 2 Geol. Mag., 1889, pp. 289, 342. s Am. Jour. Sci., 4th ser., vol. 6, 1898, p. 299. Keyes describes the dust storms of the Missouri Valley, in which great quantities of aerial sediments are carried from place to place. 4 Eleventh Ann. Rept. U. S. Geol. Survey, pt. 1, 1891, pp. 291, 435. See also.F. Leverett, Mon. U. S. Geol. Survey, vol. 38, 1899, pp. 153-184, for an account of Iowan loess. The loess of Colorado is described by S. F. Emmons in Mon. U. S. Geol. Survey, vol. 27, 1896, p. 263. 6 Geol. Mag., 1892, p. 549. 6 Quart. Jour. Geol. Soc., vol. 50, 1894, p. 472. 510 THE DATA OF GEOCHEMISTRY, by the rush of water following a thaw. T. C. Chamberlin 1 is inclined to combine the various theories concerning loess and to regard it as both glacial and eolian. Here, again, as in so many other instances, we must remember that similar products may be formed in several different ways. The loess of China may be one thing and that of the Mississippi Valley another. They are alike in their extreme com- minution but not necessarily identical in origin. A microscopic examination of loess from Muscatine, Iowa, by J. S. Differ , 2 showed that quartz was its most abundant constituent. Orthoclase, plagioclase, and hornblende were also present, with occa- sional fragments of biotite and tourmaline, some carbonates, and clay colored by oxide of iron. Chemical analyses of loess seem not to be very numerous. The following were made in the laboratory of the United States Geological Survey: Analyses of loess. A. Near Galena, Illinois. B. Near Dubuque, Iowa. C. Vicksburg, Mississippi. D. Kansas City, Missouri. Analyses A to D by R. B. Riggs. Discussed by T. C. Chamberlin and R. D. Salisbury, Sixth Ann. Rept. U. S. Geol. Survey, 1885, p. 282. Samples dried at 100°. E. Cheyenne, Wyoming. F. Denver, Colorado. G. Highland, Colorado. Analyses E to G by L. G. Eakins. Discussed by S. F. Emmons, Mon. U. S. Geol. Survey, vol. 27, 1896, p. 263, together with several other examples. A B C D E F G Si0 2 64. 61 72. 68 60. 69 74. 46 67. 10 69. 27 60. 97 ALOo 10. 64 12. 03 7. 95 12. 26 10. 26 13. 51 15. 67 Fe 2 0, 2. 61 3. 53 2. 61 3. 25 2. 52 3. 74 5. 22 FeO .51 .96 . 67 . 12 .31 1. 02 .35 MnO .05 .06 .12 .02 Trace. Trace. MgO 3. 69 1. 11 4. 56 1. 12 1. 24 1. 09 1. 60 CaO 5. 41 1. 59 8. 96 1. 69 5. 88 2. 29 2. 77 Na 2 0 1. 35 1. 68 1. 17 1. 43 1. 42 1. 70 .97 K 2 0 2. 06 2. 13 1. 08 1. 83 2. 68 3. 14 2. 28 H 2 0 2. 05 2. 50 1. 14 2. 70 5. 09 4. 19 9. 83 Ti0 2 .40 .72 .52 . 14 F oOk .06 .23 . 13 .09 . 11 .45 . 19 C0 2 6. 31 .39 9. 63 .49 3. 67 Trace. .31 C, organic . 13 .09 . 19 . 12 so 3 . 11 .51 .12 .06 Cl .07 .01 .08 .05 100. 06 100. 22 99. 62 99. 83 100. 28 100. 40 100. 16 The following analyses of adobe soil were made in the laboratory of the United States Geological Survey, by L. G. Eakins. 1 Jour. Geology, vol. 5, 1897, p. 795. See also T. C. Chamberlin and R. D. Salisbury, Sixth Ann. Rept. U. S. Geol. Survey, 1885, p. 250. 2 Bull. U. S. Geol. Survey No. 150, 1898, p. 65. THE DECOMPOSITION OF ROCKS. 511 Analyses of adobe soil. A. Salt Lake City, Utah. B. Santa Fe, New Mexico. C. Fort Wingate, New Mexico. D. Humboldt, Nevada. A B C D Si0 2 19. 24 66. 69 26. 67 44. 64 A1 2 0 3 3. 26 14. 16 .91 13. 19 FetOo 1. 09 4. 38 . 64 5. 12 MnO Trace. .09 Trace. . 13 2. 75 1. 28 .51 2. 96 CaO 38. 94 2. 49 36. 40 13. 91 Na 2 0 Trace. . 67 Trace. .59 k 2 o Trace. 1. 21 Trace. 1. 71 h 2 o 1. 67 4. 94 2. 26 3. 89 P,0« . 23 . 29 . 75 . 94 co 2 29. 57 . 77 25. 84 8. 55 Organic matter 2. 96 2. 00 5. 10 3.43 SO, .53 .41 .82 .64 Cl .11 .34 .07 . 14 100. 35 99. 72 99. 97 99. 84 The extremely variable but generally calcareous nature of these soils is sufficiently indicated. MARINE SEDIMENTS. The oceanic sediments are naturally complex, for they are derived from the most varied sources. Near shore are found the products of wave erosion, the silt brought in by streams, remnants of shells and corals, and organic matter from seaweeds. In some localities, as around coral islands, the debris consists chiefly of calcium carbonate, and that compound, as shown in a previous chapter , 1 is also formed as a chemical precipitate. Floating ice, the remnants of polar glaciers, deposits more or less stony material in the warmer parts of the ocean; and volcanic ash, from either submarine or subaerial eruptions, covers large areas on the bottom of the sea. Even cosmic dust, which has been gently fall- ing throughout all geologic time, has made perceptible contributions to the great mass of oceanic sediments . 2 Notwithstanding the diversity of these deposits, their distribution is not entirely fortuitous. River silt, for example, is an important oceanic sediment only in a belt surrounding the continents and com- paratively near shore. In relatively small amounts it is diffused through all parts of the ocean, but beyond a certain limit its influence is small. The yellow silt of the Chinese Sea, worn by the Chinese rivers from erosion of the loess, may be observed as much as a hun- dred miles from land , 3 and the turbidity of the Amazon is evident in 1 See p. 129, ante. 2 See J. Murray and A. Renard, Proc. Roy. Soc. Edinburgh, vol. 12, 1883-84, p. 474. 8 R. Pumpelly, Am. Jour. Sci., 3d ser., vol. 17, 1879, p. 133. 512 THE DATA OF GEOCHEMISTRY. the ocean at still greater distances; but the larger part of the deposits thus formed are laid down in relatively shallow water. Glacial debris, of course, occurs only near glaciers and along the tracks fol- lowed by icebergs. Certain oceanic areas are characterized by sedi- ments of organic origin; and in the deepest abysses of the ocean its floor is covered by a characteristic red clay. These varied deposits shade into one another through all manner of blendings, and yet they are distinct enough for purposes of classification. In their great volume upon Deep-sea deposits, Murray and Renard 1 adopt a classification which is perhaps as good as any yet devised. The following table shows its character and also the distribution in depth and area of the several sediments named. Mean depth and area covered by marine sediments. Mean depth, fathoms. Area, square miles. Littoral deposits (between tide marks) 62, 500 10, 000, 000 } 2, 556,800 Shallnw-watfvr fI*vnosit,s How watfir to 1 00 fathoms') [Coral mud 740 Coral sand 176 Terrigenous deposits, near land . .< Volcanic mud Volcanic sand Green mud 1, 033 243 } 600, 000 513 } 850, 000 Green sand 449 Red mud 623 100, 000 14, 500, 000 400, 000 49, 520, 000 10, 880, 000 2, 290, 000 51, 500, 000 Blue mud 1, 411 1, 044 1, 996 1, 477 2, 894 2, 730 Pelagic deposits, deep water, far from land [Pteropod ooze Globigerina ooze. . Diatom ooze Radiolarian ooze . . (.Red clay For these various products many analyses are given, and from among them a few may be cited here. The red clay which covers the largest areas is regarded by Murray and Renard as derived from . the decomposition of volcanic ejectamenta. The several oozes owe their names to the remains of living creatures which they contain, and calcium carbonate is one of their important constituents. The distribution of calcium carbonate according to depth was discussed in a former chapter 2 of this work, together with the composition of the peculiar manganese and phosphatic nodules which are often found in great numbers in the deeper parts of the sea. 1 Challenger Kept., Deep-sea deposits, 1891, table on p. 248. 2 Chapter IV, p. 131, ante. THE DECOMPOSITION OF ROCKS. 513 Analyses of marine sediments. A. Red clay. Twenty-three analyses by J. S. Brazier are tabulated on page 198 of Deep-sea deposits, and there is a discrimination between the portions soluble and insoluble in hydrochloric acid. Some of these analyses show calcium carbonate up to 60 per cent; the one selected here, as representing a more typical clay, contains the minimum of carbonate. B. Radiolarian ooze. Rich in siliceous organisms. Analysis by Brazier, page 436. C. Diatom ooze. Rich in siliceous organisms. Analysis by Brazier, page 436. D. Globigerina ooze. Twenty-one analyses are given on page 219. Analysis by Brazier, No. 42, showing low calcium carbonate. E. Globigerina ooze. Analysis by Brazier, No. 53, showing very high carbonate. F. Pteropod ooze. Analysis by Brazier, page 448. All samples dried at 110° previous to analysis. The soluble and insoluble portions in analyses A, B, and D are not separated in the following table. See also J. B. Harrison and A. J. Jukes Brown, Quart. Jour. Geol. Soc., vol. 51, 1895, p. 313, for other analyses of red clay and oceanic oozes. For 14 recent analyses of red clay, see "W. A. Caspari, Proc. Roy. Soc. Edinburgh, vol. 30, 1910, p. 183. A B C D E F Ignition 4. 50 7. 41 5. 30 7. 90 1.40 2. 00 Si0 2 62. 10 56.02 67. 92 31. 71 1. 36 3. 65 A1 2 0 3 16. 06 10. 52 .55 11. 10 .65 .80 Fe 2 0 3 11.83 14. 99 .39 7.03 .60 3. 06 Mn0 2 .55 3. 23 Trace. CaO .28 .39 .41 MgO .50 .25 . 12 CaC0 3 .92 3. 89 19. 29 37. 51 92. 54 82. 66 Oa 3 P20g .19 1.39 .41 2.80 .90 2.44 CaS0 4 .37 .41 .29 .29 .19 .73 MgC0 3 2. 70 1.50 1. 13 1. 13 .87 .76 Insoluble a 4. 72 1.49 3. 90 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 o Contains silica, alumina, and ferric oxide, not separated. G. Blue mud. Analysis by J. S. Brazier, page 448. H. Red mud. Analysis by M. Hornung, page 445. Dried at 100°. I. Green mud. Analysis by Brazier, page 449. J. Green sand. Analysis by Brazier, page 449. K. Volcanic mud. Analysis by Brazier, page 450. Analyses G to IC represent “terrigenous ” deposits. Brazier’s samples were all dried at 110°. The soluble and insoluble portions are here united. G H I J K Ignition 5. 60 6.02 3.30 9. 10 6. 22 Si0 2 64. 20 31. 66 31.27 29. 70 34. 12 A1 2 0 3 13. 55 9.21 4. 08 3.25 9. 22 Fe 2 0 3 8.38 4. 52 12. 72 5. 05 15. 46 Mn0 2 Trace. CaO 2. 51 25. 68 .30 .22 1. 44 MgO .25 2. 07 .12 .13 .22 Na 2 0 1. 63 K 2 0 1. 33 CaC0 3 2. 94 46.36 49. 46 32. 22 Ca 3 P 2 0 8 1.39 . 70 Trace. Trace. CaS0 4 .42 . 58 1. 07 . 27 MgC0 3 : .76 .57 2.02 .83 so 3 .27 co 2 17. 13 Cl 2. 46 Less 0=C1 100. 00 101. 98 .87 100. 00 100. 00 100. 00 101. 11 97270°— Bull. 616—16 33 514 THE DATA OF GEOCHEMISTRY. These analyses serve well enough to show the variable character of the oceanic sediments, but they are in several respects incomplete. In order to determine the composition of the oceanic clays more minutely, two analyses have been made in the laboratory of the United States Geological Survey upon material kindly furnished by Sir John Murray. The samples analyzed were composites of many individual specimens, brought together from all of the great oceans and collected partly by the Challenger and partly by other expeditions. The data are as follows, reduced to uniformity by rejec- tion of sea salts, calcium carbonate, and hygroscopic water, and recal- culation of the remainder to 100 per cent. Analyses of composite samples of marine clays. A. Composite of fifty-one samples of the ‘‘red clay.” Analyzed by G. Steiger, with special determina- tions by W. F. Hillebrand and E. C. Sullivan. B. Composite of fifty-two samples of “terrigenous clays,” namely, four “green muds” and forty-eight “blue muds.” Analysis by G. Steiger. Si0 2 Ti0 2 A1 2 0 3 Cr 2 0 3 . . . . Fe 2 0 3 FeO NiO, CoO. MnO Mn0 2 . . . . MgO CaO SrO BaO K 2 0 Na 2 0 V 2 0 3 •A-S 2 0 3 . . . . Mo0 3 . . . . P 2 0 5 s CuO PbO ZnO C h 2 o 54. 48 .98 15. 94 .012 8. 66 .84 .039 1. 21 3. 31 1. 96 .056 .20 2. 85 2. 05 .035 .001 Trace. .30 .024 .008 .005 7.04 57. 05 1. 27 17. 22 .05 5. 07 2. 30 .0630 .12 2. i7 2. 04 .03 .06 2. 25 1. 05 .03 Trace. \*2i" .13 .0160 .0004 .0070 1. 69 7. 17 100. 000 99. 9964 These figures give the average composition of the two oceanic sedi- ments and show the distribution in them of the minor and rarer con- stituents. Even these analyses need to be supplemented by others, of which many can be found scattered through the literature of ocean- THE DECOMPOSITION OF ROCKS. 515 ography. 1 The data are abundant, but their value upon the purely chemical side is very uneven. Few conclusions can be deduced from them. J. Y. Buchanan, 2 who found free sulphur in a number of marine muds, thinks that sulphates were reduced to sulphides by passing through the digestive organs of marine ground fauna, and points out that matter at the bottom of the sea is subject also to reoxidation by dissolved oxygen. When oxidation is in excess of reduction red sediments are formed; if the reducing process prepon- derates, the sediments are blue. In the Black Sea, according to N. Androussow, 3 the sulphates contained in the water are also partly reduced by micro-organisms, which liberate hydrogen sulphide. A portion of this gas is reoxidized, with some liberation of sulphur; another part takes up iron from the sediments and forms abundant deposits of pyrites. The calcareous oozes obviously represent calcium carbonate absorbed by living organisms from its solution in sea water and depos- ited with their remains after death. It therefore owes its origin to rock decomposition, during which the lime was removed to be carried in solution by rivers to the sea. The siliceous oozes were formed in a similar manner by radiolarians and diatoms, which, as J. Murray and R. Irvine 4 have shown, are able to decompose the suspended particles of clay that reach the ocean and to assimilate their silica. A slimy mass of siliceous algae analyzed by Murray and Irvine con- tained 77 per cent of silica, 1.38 of alumina, 16.75 of organic matter, and 4.87 of water. From materials of this kind, which are very abundant in the ocean, these particular oozes were produced, but their primary substance — silt, or volcanic ash, or atmospheric dust — came from the decomposition of rocks upon the land. In some cases siliceous deposits have been developed in another way, namely, by the silicification of shells and corals. Remains of this kind are plen- tifully found in sedimentary rocks, and the process of their forma- tion can be imitated artificially. A. H. Church, 5 by allowing a very weak solution of colloidal silica to percolate through a frag- ment of coral, succeeded in dissolving away the calcium carbonate and leaving in its place a siliceous pseudomorph. 1 See, for example, K. Natterer, on Mediterranean muds, Monatsh. Chemie, vol. 14, 1893, p. 624; vol. 15, 1894, p. 530; also upon Red Sea deposits, idem, vol. 20, 1899, p. 1. L. Schmelck (Den Norske-Nordhavs Expedition, pt. 9) gives many analyses of marine clays. J. Y. Buchanan (Proc. Roy. Soc. Edinburgh, vol. 18, 1890-91, p. 131) reports partial analyses of Mediterranean samples. A. and H. Strecker (Liebig’s Annalen, vol. 95, 1855, p. 177) describe a peculiar mud from the Sandefjord, Norway. A later study of the same substance was published by E. Bodtker (Liebig’s Annalen, vol. 302, 1898, p. 43). For a bibliography of oceanic sedimentation see K. Andrde, Geol. Rundschau, vol. 3, p. 324, 1912. 2 Proc. Roy. Soc. Edinburgh, vol. 18, 1890-91, p. 17. * Guide des excursions du VII Cong. gdol. intemat., No. 29, 1897, p. 6. * Proc. Roy. Soc. Edinburgh, vol. 18, 1890-91, p. 229. & J our. Chem. Soc., vol. 15, 1862, p. 109. 516 THE DATA OF GEOCHEMISTRY. GIjAUCONITE. In oceanic sediments, and chiefly near the “mud line” surrounding the continental shores, the important mineral glauconite is found in actual process of formation. This green, granular silicate of potas- sium and iron occurs in rocks of nearly all geologic ages, from the Cambrian down to the most recent horizons, and there has been much discussion over its nature and origin. In composition it is exceed- ingly variable, for the definite compound is never found in a state of purity, but is always contaminated by alteration products and other extraneous substances. As an oceanic deposit glauconite is devel- oped principally in the interior of shells, and organic matter is be- lieved to play a part in its formation. According to Murray and Renard , 1 the shell is first filled with fine silt or mud upon which the organic matter of the dead animal can act. Through intervention of the sulphates contained in the sea water, the iron of the mud is con- verted into sulphide, which oxidizes later to ferric hydroxide. At the same time alumina is removed from the sediments by solution and colloidal silica is liberated. The latter reacts upon the ferric hydroxide in presence of potassium salts extracted from adjacent minerals, and so glauconite is produced. This view is sustained by other evidence, namely, the constant association of the glauconite shells with the debris of rocks in which potassium-bearing minerals, such as orthoclase and muscovite, occur . 2 This theory of Murray and Renard seems to be fairly satisfactory, so far as it goes, but it does not cover the entire ground. It applies to the glauconite which is now forming upon the sea bottom, but not to all occurrences of glauconite in the sedimentary rocks. In an important memoir L. Cayeux 3 has shown that in certain instances glauconite has formed subsequent to the consolidation of its rocky matrix, and while he admits that organic matter has assisted its development within shells, the mineral can be produced by some quite different process. What this process is he does not explain; he merely shows that glauconite can form without the intervention of organisms and that its mode of genesis is at least twofold. Inci- centally also he states that ferric hydroxide and pyrite are produced by the decomposition of glauconite, an observation which seems to indicate that the reactions predicated by Murray and Renard may be reversible. 1 Challenger Rept., Deep-sea deposits, 1891, p. 383. 2 For other discussions relative to the origin of glauconite see C. W. von Giimbel, Sitzungsb. K. Akad. Wiss. Miinchen, vol. 16, 1886, p. 417; vol. 28, 1896, p. 545. Also D. S. Calderon, D. F. Chaves, and P. del Pulgar, Anales Soc. espan. hist, nat., vol. 23, 1894, p. 8. The older literature of the subject is unimpor- tant for present purposes. * Contributions & l’&ude micrographiquo des terrains s&limentaires: M&n. Soc. g&>l. du 'Cord, vol. 4, pt. 2, 1897, pp. 163-184. THE DECOMPOSITION OF ROCKS. 517 The granules of glauconite from marine mud and from the sedi- mentary rocks, although not found as definite crystals, have never- theless a distinct cleavage, and are interpreted by A. Lacroix 1 as monoclinic and analogous to the micas. There is, however, another mineral, celadonite, which is regarded by Dana and other writers as a separate species, but which resembles glauconite so closely in com- position that it may be the same thing. It occurs as a decomposition product of augite in various basaltic rocks, is green like glauconite, but earthy in texture, and never granular. It is easily confounded with other green chloritic minerals and its diagnosis is never certain unless supported by a complete chemical analysis. C. W. von Gum- bel 2 and K. Glinka 3 both identify it chemically with glauconite, despite its entirely different origin, a conclusion which, if sustained, gives us another illustration of the fact that a chemical compound may be produced by several distinct processes. Still another min- eral, found in the iron-bearing rocks of the Mesabi district, and named greenalite by C. K. Leith 4 has been confounded with glau- conite, although it is free from potassium and its iron is practically all in the ferrous state. In glauconite the iron is mainly ferric, and potassium is one of its essential constituents. According to the best analyses, glauconite probably has, when pure, the composition repre- sented by the formula Fe /// KSi 2 0 6 .aq., in which some iron is replaced by aluminum, and other bases partly replace K. 5 This formulation is not final, neither does it suggest any relationship between glau- conite and the micas. It rests upon Glinka’s analyses of Russian glauconite, in which the material was freed from impurities by means of heavy solutions. The water in the formula is probably for the most part “zeolitic” and not constitutional, as in the case of analcite, a silicate of similar chemical type. The following analyses of glauconite and celadonite will serve to show the variability of the material. 6 1 Min6ralogie de la France, vol. 1, 1893-1895, p. 407. Lacroix gives a number of analyses of French and Belgian glauconites. 2 Sitzungsb. K. Akad. Wiss. Miinchen, vol. 26, 1896, p. 545. s Zeitschr. Kryst. Min., vol. 30, 1899, p. 390. Abstract from a Russian original. 4 Mon. U. S. Geol. Survey, vol. 43, 1903, p. 240. Leith gives a long table of glauconite analyses. 5 See discussion by F. W. Clarke in Mon. U. S. Geol. Survey, vol. 43, 1903, p. 243. Compare L. W. Collet and G. W. Lee, Compt. Rend., vol. 142, 1906, p. 999. The authors give an analysis of very pure marine glauconite. Two other analyses are given by W. A. Caspari, Proc. Roy. Soc. Edinburgh, vol. 30, 1910, p. 364. Caspari also describes the synthesis of a compound resembling glauconite. An important mono- graph by Collet, Les d6p6ts marins, was published at Paris in 1908. 6 Many analyses of greensand marls are given by G. H. Cook, in Geology of New Jersey, 1868, pp. 414 et seq. On New Jersey greensands see also W. B. Clark, Jour. Geology, vol. 2, 1894, p. 161. On Irish glau- conite, see A. J. Hoskins, Geol. Mag., 1895, p. 317. 518 THE DATA OF GEOCHEMISTRY. Analyses of glauconite and celadonite. A. Glauconite, from Woodburn, Antrim, Ireland. Analysis by A. P. Hoskins, Geol. Mag., 1895, p. 320. B. Glauconite from Cretaceous sandstone, Padi, Government Saratoff, Russia. One of ten analyses, by K. Glinka (Zeitscbr. Kryst. Min., vol. 30, 1899, p. 390), of Russian material from the Lower Silurian, Jurassic, Eocene, and Cretaceous. This sample lost 4.43 per cent of water at 100°, but regained it in twenty -four hours. C. Glauconite from greensand marl, Hanover County, Virginia. Analysis by M. B. Corse and C. Bas- kerville, Am. Chem. Jour., vol. 14, 1892, p. 627. 8.22 per cent of the silica is stated separately as quartz. D. Oceanic glauconite, mean of four analyses made by L. Sipocz for Murray and Renard, Challenger Rept., Deep-sea deposits, 1891, p. 387. E. Glauconite, Monte Brione, Lake Garda, Italy. Analysis by A. Sch wager. Described by C. W. von Giimbel, Sitzungsb. Akad. Miinchen, vol. 26, 1896, p. 545. F. Celadonite, Monte Baldo, near Verona, Italy. Analysis by Sch wager. See Giimbel, loc. cit. G. Celadonite, mean of four analyses of material from Scottish localities, by M. F. Heddle. Trans. Roy. Soc. Edinburgh, vol. 29, 1880, p. 102. A B C D E F G Si0 2 40. 00 48. 95 51. 56 53. 61 50. 36 55. 80 54. 84 A1 2 0 3 13. 00 7. 66 6. 62 9. 56 7. 04 3. 20 3. 52 Fe 9 0, 16. 81 23. 43 15. 16 21. 46 19. 13 16. 85 12. 64 FeO 10. 17 1. 32 8. 33 1. 58 3. 95 3. 88 4. 90 MnO Trace. .06 . 12 .24 MgO 1. 97 2. 97 .95 2. 87 4. 08 5. 32 6. 65 CaO 1. 97 .57 .62 1. 39 .91 . 16 .89 Na 2 0 2. 16 . 98 1. 84 .42 1. 58 1. 12 . 39 K 2 0 8. 21 9. 54 4. 15 3. 49 6. 62 9. 04 7.00 Li 2 0 .01 H 2 0 6. 19 4. 93 10. 32 5. 96 4. 67 9. 62 Organic } 6.32 Trace. Ti0 2 .02 . 24 P,(X .26 .07 100. 48 100. 35 99. 55 100. 34 100. 34 100. 47 100. 69 If, now, we assume that celadonite and glauconite are at bottom the same ferripotassic silicate, differing only in their impurities, we may begin to see that the several modes of its formation are not ab- solutely different after all. Probably, in all their occurrences, the final reaction is the same, namely, the absorption of potassium and soluble silica by colloidal ferric hydroxide. In the ocean these materials are prepared by the action of decaying animal matter upon ferruginous clays and fragments of potassium-bearing silicates. In the sedimentary rocks, when glauconite appears as a late product, the action of percolating waters upon the hydroxide would account for its formation. In igneous rocks the hydroxide is derived from augite, or perhaps from olivine, and percolating waters again come into play. Thus the various productions of glauconite and celado- nite become the results of a single process, which is exactly equivalent to that in which potassium compounds are taken up by clays. The observation of L. Cayeux 1 that glauconite is frequently present in arable soils, in all conditions from perfect freshness to complete alteration into limonite, suggests that perhaps the formation of the species is one of the modes by which potassium is withdrawn from its solution in the ground waters. i Annales Soc. g6ol. du Nord, vol. 34, 1905, p. 146 THE DECOMPOSITION OF ROCKS. 519 PHOSPHATE ROCK. Among the phosphates of the igneous and crystalline rocks, only one, apatite, has any large significance. Monazite and xenotime are altogether subordinate. Apatite, as was shown in previous chap- ters 1 is widely distributed, but in relatively small proportions; although it is sometimes concentrated into large deposits or in veins. The commercially important apatites of Canada, Norway, and Spain are segregations of this kind . 2 By various processes, which are not yet fully understood, apatite undergoes alteration, and by percolating carbonated waters it is slowly dissolved. Some^of the phosphoric acid, thus removed in solution, is carried by rivers to the sea, where it is largely absorbed by living organisms. Some of it reacts upon other products of rock decomposition, forming new secondary phosphates. Another portion is retained by the soil, whence it is extracted by plants, to pass from them into the bodies of animals. From organic sources, such as animal remains, the largest deposits of phosphates are derived. Between the original apatite and a bed of phosphorite there are many stages whose sequence is not always the same. The solubility of apatite and of the other forms of calcium phos- phate has been studied by many investigators . 3 R. Muller 4 has shown that apatite dissolves in carbonated waters, and the fact that the solubility of calcium phosphate is increased by humus acids has been observed by H. Minssen and B. Tacke . 5 C. L. Reese , 6 in a series of experiments upon calcium phosphate, found that it dissolved per- ceptibly in swamp waters rich in organic matter. Carbonated waters also dissolved it freely, but it was redeposited when the solution was allowed to stand over calcium carbonate. In presence of the car- bonate, then, the phosphate would probably not be dissolved, while carbonate could pass into solution. Other salts in solution may assist or hinder the solubility of calcium phosphate, and since natural waters differ in composition the solvent process is necessarily variable. Cameron and Hurst , 7 who studied the solution of iron, aluminum, and calcium phosphate, showed that the process is one of hydrolysis, 1 See p. 355 and also the analyses of igneous rocks given in Chapter XI. 2 For good summaries relative to the occurrence of economically important phosphates of lime / see R. A. F. Penrose, Bull. U. S. Geol. Survey No. 46, 1888; A. Carnot, Annales des mines, 9th ser., vol. 10, 1896, p. 137; and E. Nivoit, in Fremy’s Encyclopedic chimique, vol. 5, sec. 1, pt. 2, 1884, p. 83. All these memoirs contain numerous analyses, and Penrose gives a bibliography of the subject down to 1888. 3 See F. K. Cameron and L. A. Hurst, Jour. Am. Chem. Soc., vol. 26, 1904, p. 885. These writers give abundant literature references. See also Cameron and A. Seidell, idem, vol. 26, 1904, p. 1454; vol. 27, 1905, p. 1503. Earlier papers by S. P. Sharpies (Am. Jour. Sci., 3d ser., vol. 1, 1871, p. 171) and T. Schlosing (Compt. Rend., vol. 131, 1900, p. 149) may also be noticed. 4 Jahrb. K.-k. geol. Reichsanstalt, vol. 27, Min. Mitt., 1877, p. 25. See also ante, p. 355. 6 Jour. Chem. Soc., vol. 78, pt. 2, 1900, p. 618. Abstract. 6 Am. Jour. Sci., 3d ser., vol. 43, 1892, p. 402. 7 Loc. cit. 520 THE DATA OF GEOCHEMISTRY. the solution becoming acid, 1 and less soluble basic phosphates being left behind; that is, the solution contains acid ions, corresponding " either to free acid or to acid salts — a condition which must materially affect the action of the liquid upon the substances with which it comes in contact. R. Warington, 2 for example, found that a solu- tion of calcium phosphate in carbonated water was perfectly decom- posed by hydroxides of iron and aluminum — a reaction which must often occur in soils. By reactions of this kind, probably, many well- known minerals have been produced; but, since iron compounds occur in natural solutions more largely than salts of aluminum, the iron phosphates are more numerous and more widely distributed. The “blue earth,” vivianite, Fe 3 P 2 0 8 .8H 2 0, for example, is not uncom- mon in clays; it is found lining belemnites and other fossils at Mul- lica Hill, New Jersey; and near Edgeville, Kentucky, W. L. Dudley 3 found plant roots almost completely transformed, by a process of re- placement, into this mineral. Other phosphates of iron, commonly found associated with sedimentary beds of limonite, are dufrenite, strengite, phosphosiderite, barrandite, koninckite, cacoxenite, be- raunite, ludlamite, calcioferrite, borickite, etc. The aluminum phosphates, omitting several of doubtful character, are wavellite, fischerite, variscite, turquois, callainite, peganite, sphaerite, evansite, wardite, and zepharovichite. Most of these minerals are rare species, found in very few localities, and need no further consideration here. 4 Wavellite, however, has been mined near Mount Holly Springs, Pennsylvania, and used as a source of phosphoric acid. 5 Aluminum phosphates are sometimes formed by the direct action of phosphatic solutions upon igneous rocks, or even upon limestones containing much clay. The source of the phosphates in several such cases is found in beds of guano deposited by sea fowl upon rocky islets, or by colonies of bats in caves. Guano is rich in phosphatic material, and a number of distinct mineral species have been dis- covered in guano beds. 6 The following compounds are the best known among them: Monetite HCaP0 4 . Brushite HCaP0 4 . 2H 2 0 . Metabrushite 2HCaP0 4 .3H 2 0 . Martinite 2H 2 Ca 5 (P0 4 ) 4 .H 2 0 . 1 Apatite gives alkaline reactions. F. K. Cameron and A. Seidell, Jour. Am. Chem. Soc., vol. 27, 1905, p. 1510. 2 Jour. Chem. Soc., vol. 19, 1866, p. 296. 3 Am. Jour. Sci., 3d ser., vol. 40, 1890, p. 120. * For details concerning these minerals, see Dana’s System of Mineralogy and its supplements. On the varieties of calcium phosphate known as osteolite and staffelite, see A. Schwantke, Centralbl. Min., Geol. u. Pal., 1905, p. 641. 6 See G. W. Stose, Bull. U. S. Geol. Survey No. 315, 1907, p. 474. 6 On the phosphates found in the bat guano of the Skipton Caves, Australia, see R. W. E.McIvor, Chem. News, vol. 55, 1887, p. 215; vol. 85, 1902, pp. 181, 217. Mclvor names three of the ammonium-magnesium phosphates— dittmarite, muellerite, and schertelite. THE DECOMPOSITION OF ROCKS. 521 Collophanite Ca 3 P 2 0 8 . H 2 0 . Bobierrite Mg 3 P 2 0 8 .8H 2 0 . Newberyite HMgP0 4 .3H 2 0. Hannayite. Mg 3 P 2 0 8 .2H 2 NH 4 P0 4 .8H 2 0. Struvite NH 4 MgP0 4 .6II 2 0 . Stercorite HNaNH 4 P0 4 .4H 2 0 . Several of these compounds, it will be observed, are acid phos- phates, and three of them contain ammonium. Dissolved by atmos- pheric waters, they react upon the decomposing rocks beneath the guano and produce changes of a notable kind. Where they find limestone, they convert it into calcium phosphate; when they attack igneous rocks, they produce a phosphate of aluminum. The last- named substance may also be formed from the hydroxide of alumi- num which is present in many clays. On the islands of Navassa, Som- brero, Mona, and Moneta, in the West Indies , 1 limestones have been thus transformed; the other reaction may be more fully considered now. On Clipperton Atoll, in the North Pacific, J. J. H. Teall 2 found a phosphatized trachyte, the alteration being clearly due to leachings from guano. A similar alteration of andesite was discovered by A. Lacroix 3 on Pearl Islet, off the coast of Martinique. In both cases feldspars furnished the alumina for the phosphate that was found. Another phosphate of similar character, from the island of Redonda, in the West Indies, was described by C. U. Shepard , 4 but nothing is said of its petrologic origin. Another example, ana- lyzed by A. Andouard , 5 came from the islet of Grand-Connetable, near the coast of French Guiana. All of these represent changes brought about by percolations from bird guano. In the Minerva grotto, Department of THerault, France, A. Gau- tier 6 found brushite, tribasic calcium phosphate, and a phosphate of aluminum to which he gave the name minervite. To this he 1 For the Navassa phosphate, see E. V. dTnvilliers, Bull. Geol. Soc. America, vol. 2, 1891, p. 75. W. B. M. Davidson (Trans. Am. Inst. Min. Eng., vol. 21, 1892-93, p. 139) thinks it may be a residual concentra- tion from phosphatic limestone and not a guano product. For Sombrero, see A. A. Julien, Am. Jour. Sci., 2d ser., vol. 36, 1863, p. 424. For Mona and Moneta, see C. U. Shepard, jr., Am. Jour. Sci., 3d ser.,vol. 23, 1882, p. 400. See also S. P. Sharpies, Proc. Boston Soc. Nat. Hist., vol. 22, 1883, p. 242, on phosphates from the guano caves of the Caicos Islands, which contain considerable admixtures of calcium sulphate. K. Martin (Zeitschr. Deutsch. geol. Gesell., vol. 31, 1879, p. 473), has described the deposits of phosphate on the island of Bonaire. N. H. Darton (Am. Jour. Sci., 3d ser., vol. 41, 1891, p. 102) and W. H. Dali and G. D. Harris (Bull. U. S. Geol. Survey No. 84, 1892) regard the phosphates of Florida as possibly due to guano leachings. The same view was also advocated by L. C. Johnson, Am. Jour. Sci., 3d ser., vol. 45, 1893, p. 407. On the Aruba phosphates see G. Hughes, Quart. Jour. Geol. Soc., vol. 41, 1885, p. 80. 2 Quart. Jour. Geol. Soc., vol. 54, 1898, p. 230. * Bull. Soc. min., vol. 28, 1905, p. 13. Lacroix (Compt. Rend., vol. 143,1906, p. 661) has also reported an occurrence of phosphatized trachyte on the island of San Thome, in the Gulf of Guinea. In this case again, guano was the agent of alteration. * Am. Jour. Sci., 2d ser., vol. 47, 1869, p. 428. See also C. H. Hitchcock, Bull. Geol. Soc. America, vol. 2, 1891, p. 6. 6 Compt. Rend., vol. 119, 1894, p. 1011. 6 Annales des mines, 9th ser., vol. 5, 1894, p. 1. Compt. Rend., vol. 116, 1893, pp. 928, 1023. Recent papers by Gautier are in Compt. Rend., vol. 158, p. 912, 1914, and Bull. Soc. chim., 4th ser., vol. 15, 1914, p. 533. 522 THE DATA OF GEOCHEMISTRY. first assigned the formula A1 2 P 2 0 8 .7H 2 0, but later investigations have shown that potassium is an essential constituent of the mineral. This was proved by A. Carnot/ who also described a substance similar to minervite, from a cave near Oran, in Algeria. In this case the phosphatic deposits seem to have been formed by infiltra- tions from without the cavern, and the same is true of a white, pulverulent substance described by J. C. H. Mingaye 1 2 from the Jenolan caves in New South Wales. Here no evidence of guano could be found, and Mingaye ascribed the phosphatic solution to leachings of river silt containing bones or other organic matter and directly overlying the caves. The analyses are as follows: Analyses of phosphatic deposits. A. Clipperton Atoll, Teall. E. Minerva Grotto, Carnot. B. Martinique, analysis by Arsandaux. F. Oran, Carnot. C. Redonda, Shepard. G. Jenolan caves, Mingaye. D. Minerva Grotto, Gautier, recent. H. Controne, Sicily, Casoria. A B c D E F G Ho PXL 38.5 41. 20 43. 20 40. 40 37. 28 35. 17 40. 83 37. 10 A1 2 0 3 25.9 34. 20 14. 40 21. 60 18. 59 18. 18 20. 70 22. 89 Fe*Oo . 7.4 16. 60 .50 .83 .20 1. 17 Trace. .33 Trace. Trace. CaO Trace. .57 .13 1.40 .31 Trace. k 2 o... 7. 00 8. 28 5. 80 9. 01 8. 04 Na 2 0 .30 .02 (NHJoO .47 nh 3 .52 .48 .61 F Trace. Trace. CaF 2 .31 Cl Trace. Trace. so 3 Trace. Trace. Si0 2 } 5.0 1. 60 11. 60 .36 Insol . 14 | 4. 35 1. 12 H 2 0 J 23.0 24. 50 24. 00 28. 73 28. 20 28. 20 27. 69 b 29. 16 99.8 99. 90 100. 37 99. 58 99. 78 99. 74 99. 55 99. 35 a This substance, named palmerite by E. Casoria (Zeitschr. Kryst. Min., vol. 42, 1906, p. 87), from near Controne, Sicily, is probably identical with minervite. It was found in a layer under bat guano. See also A. Lacroix, Bull. Soc. min., vol. 33, 1910, p. 34. Lacroix assigns a very complex formula to minervite. b Loss in ignition. Although these analyses do not represent pure compounds, they yield approximations to simple formula. A and B are not far from variscite, A1P0 4 .2H 2 0. C suggests the analogous barrandite, (Al,Fe)P0 4 .2H 2 0. Minervite, especially as shown in Mingaye’s analy- sis, probably contains a salt of the composition H 2 KA1 2 (P0 4 ) 3 .6H 2 0. Gautier assigns it a more complex formula and further investigation of it is desirable. 1 Annales des mines, 9th ser., vol. 8, 1895, p. 319. Compt. Rend., vol. 121, 1895, p. 152. 2 Rec. Geol. Survey New South Wales, vol. 6, 1899, p. 111. Mingaye gives analyses of several other phos- phates found in these caverns. Phosphates of similar origin are described by D. Mawson and W. T. Cooke in Trans. Roy. Soc. South Australia, vol. 31, 1907, p. 65. THE DECOMPOSITION OF ROCKS. 523 The phosphates of the Minerva grotto, according to Gautier, 1 were formed by the action of decomposing animal matter upon gibbsite, clay, and limestone. In order to support this opinion, he proved experimentally that solutions of ammonium phosphate, which, as we have seen, may be derived from guano, will produce the required transformations. Gelatinous alumina, digested with ammonium phosphate, gave a crystalline product resembling minervite, and even a clay was altered by the reagent. Siderite, FeC0 3 , similarly treated with ammonium phosphate, was converted into a salt of the composition Fe 3 (P0 4 ) 2 .6H 2 0; and limestone was found to be trans- formed into calcium phosphate. That is, a known product of organic decomposition will so act upon mineral substances as to generate phosphates resembling those that were actually found. An outline is thus furnished for a general theory of phosphatization, which is supported both by laboratory investigation and by the observation of natural occurrences. The decaying animal matter, in presence of bones or phosphatic shells, can form soluble phosphates, and the latter, acting in solution upon clays, hydroxides, or carbon- ates, bring about the final transformations. The larger deposits of calcium phosphate, or phosphorite, are probably all of marine origin. 2 Unlike the crystalline apatite they are amorphous, and may be either compact, earthy, or concretionary. Nodular or pebble forms are common. In composition the purest phosphorites approach apatite, or, more specifically, fluorapatite, Ca 5 (P0 4 ) 3 F; but some varieties are more nearly the normal trical- cium phosphate, Ca 3 (P0 4 ) 2 . According to A. Carnot, 3 the concre- tionary phosphates are deficient in fluorine, while in the sedimentary forms it is present in nearly the apatite ratio. In the phosphorites of France, A. Lacroix 4 identifies collophanite, dahllite (Ca 6 (P0 4 ) 4 .CaC0 3 .JH 2 0) and francolite, which also contains calcium carbonate. To the phos- phorite of Quercy, which is a mixture of the other species, he gives the name quercylite. To apparently homogeneous brown grains from the chalk of Ciply, in Belgium, J. Ortlieb 5 assigned the formula 4Ca0.2P 2 0 5 .Si0 2 , regarding the substance as a definite mineral species to which he gave the name ciplyte. In an Algerian phosphate, G. Schuler 6 found 1 Annales des Mines, 9th ser., vol. 5, 1894, p. 1. Compt. Rend., vol. 116, 1893, pp. 928, 1023. 2 Even the highly crystallized Canadian apatites of the Grenville series are regarded by W. H. McNaim as originally marine deposits which have undergone metamorphism. Trans. Canadian Inst., vol. 8, p. 495. 3 Compt. Rend., vol. 114, 1892, p. 1003. * Idem, vol. 150, 1910, pp. 1213, 1388. See also his Min&alogie de la France, vol. 4, pp. 555-586. On dahllite, etc., see also A. F. Rogers, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 475, and Mineralog. Mag., vol. 17, 1914, p. 155. To a mineral of the composition CasPaOs.CaO Rogers gives the name voelckerite. 6 Annales Soc. g4ol. du Nord, vol. 16, 1888-89, p. 270. e Zeitschr. angew. Chemie, 1898, p. 1101. 524 THE DATA OF GEOCHEMISTRY. chromium to an average amount of 0.057 per cent of Cr 2 0 3 . Oxides of iron, alumina, magnesia, calcium carbonate, gypsum, silica, sand, and clay are common impurities. Nitrogenous organic matter is also often present. Some so-called phosphate rocks are merely phosphatized limestones, sandstones, or shales. In certain Cre- taceous sandstones of Russia, calcium phosphate occurs as a cement for the sand grains and also in the form of fossil bones and fossil wood. The wood has been completely replaced by phosphate. 1 Although bone is itself largely composed of calcium phosphate, fossil bones are not identical chemically with recent bones. The fossils show an enrichment in calcium carbonate, iron oxide, and fluorine, as A. Carnot 2 has shown, and especially in fluorine. Modern bones, from various animals, were found by Carnot to contain a minimum proportion of fluorine; Tertiary bones were much richer; Triassic and Cretaceous bones still more so; and in bones from Silurian and Devo- nian formations the ratio of fluoride to phosphate was nearly that of apatite. This progressive enrichment in fluorine Carnot attributes to the agency of percolating waters, carrying small quantities of fluo- rides in solution. He cites a number of references to the presence of fluorides in mineral springs, and in water from the Atlantic he found fluorine to the extent of 0.822 gram in a cubic meter. Iodine, which is also of oceanic origin, has repeatedly been detected in phosphorites, but the presence of bromine is more doubtful. 3 The small traces of phosphates which are present in sea water are more or less absorbed into the shells, bones, and tissues of marine animals, and so concentrated to some extent. When the animals die their remains are scattered through the ooze of the sea bottom, and feebly phosphatic deposits are thus formed. The calcium phosphate, however, tends to become still more concentrated, for the carbonate with which it is commingled is more freely soluble, and so is par- tially removed. This process is assisted by the carbonic acid formed during the decomposition of the animal matter. 4 Some phosphate is also dissolved, but it is in part redeposited around nuclei, such as shells or fragments of bone, forming the phosphatic nodules which are so often found upon the ocean floor. 5 6 Similar nodules are com- mon in beds of phosphorite and in some localities they constitute its valuable portions. They are also found disseminated in deposits of green sand, associated with the glauconite which was laid down at 1 See a table of 18 analyses by A. Engelhardt, Claus, P. Latschinow, and P. Kostychew in Revue de geologie, vol. 7, 1867-68, p. 320. The wood, bone, and cement have practically the same composition. 2 Annales des mines, 9th ser., vol. 3, 1893, p. 155. In a dinosaurian bone from Colorado, L. G. Eakins, in the laboratory of the United States Geological Survey, found 2.12 per cent of fluorine. 3 See F. Kuhlmann, Compt. Rend., vol. 75, 1872, p. 1678. * See discussion by L. Kruft, Neues Jahrb., Beil. Band 15, 1902, p. 1. This memoir relates to the distri- bution of phosphorite in the older Paleozoic formations of Europe. 6 See J. Murray and A. F. Renard, Challenger Rept., Deep-sea deposits, 1891, pp. 397-400. Also ante, in Chapter IV, p. 135. THE DECOMPOSITION OF ROCKS. 525 the same time. The replacement of calcareous shells by phosphates was clearly traced by A. F. Renard and J. Cornet 1 in their study of the Cretaceous phosphorites of Belgium. The organic remains which contribute to the formation of phos- phorites vary widely as regards richness in phosphates. Bones are the richest; crustacean remains probably come next; mollusks and corals are the poorest. As a rule, molluscan shells and corals consist mainly of calcium carbonate, but some brachiopods are highly phos- phatic. In a recent lingula, for instance, W. E. Logan and T. S. Hunt 2 found 85.79 per cent of calcium phosphate. The fossil casts of a gas- tropod, Cyclora, are also, according to A. M. Miller, 3 rich in phos- phate. The Cambrian phosphates of Wales are regarded by H. Hicks 4 as derived in large part from crustaceans, a supposition which is borne out by W. H. Hudleston’s analyses. 5 The shell of a giant trilobite contained 17.05 per cent of P 2 0 5 ; the shell of a recent lobster yielded 3.26 per cent, and the average amount found in an entire lobster was 0.76 per cent. Where crustacean remains are abundant, the proportion of phosphoric acid ought to be relatively high. The deposits thus formed by animal remains, upon the bottom of the sea, are at best but moderately phosphatic. A further concentra- tion is effected after the sediments have been elevated into land sur- faces, when atmospheric agencies begin to work upon them. First, beds of phosphatic chalk or limestone are formed, from which, by leaching with meteoric or subterranean waters, the excess of calcium carbonate is washed away. The less soluble phosphate then remains as a residuary deposit, more or less impure, and varying much in richness. The beds near Mons, in Belgium, according to F. L. Cornet, 6 were thus derived from phosphatic chalk, from which the calcareous shells have disappeared, while the flints, siliceous sponges, and vertebrate bones are unchanged. According to Chateau 7 the Eocene phosphates of Algeria were concentrated in the same way, from animal and vegetable debris laid down in shallow salt-water lagoons. The beds also show signs of local precipitation of phos- phates which had previously been dissolved. So long ago as 1870 this theory of concentration by leaching was proposed by N. S. 1 Bull. Acad. roy. sci. Belgique, vol. 21, 1891, p. 126. 2 Am. Jour. Sci., 2d ser., vol. 17, 1854, p. 236. The phosphatic character of lingula has since been verified in the laboratory of the U. S. Geological Survey. s Am. Geologist, vol. 17, 1896, p. 74. * Quart. Jour. Geol. Soc., vol. 31, 1875, p. 368. On p. 357 of the same journal there is another paper by D. C. Davies on the same region. W. D. Matthew (Trans. New York Acad. Sci., vol. 12, p. 108) has de- scribed phosphatic nodules from the Cambrian of New Brunswick. 6 Quart. Jour. Geol. Soc., vol. 31, 1875, p. 376. e Idem, vol. 42, 1886, p. 325. 7 M6m. Soc. ingtfn. civils, August, 1897, p. 193. Analyses of Algerian phosphates, by H. and A. Malbot, are given in Compt. Rend., vol. 121, 1895, p. 442. The phosphorites of Tunis are described by P. Thomas in Bull. Soc. g6ol. France, 3d ser., vol. 19, 1891, p. 370. See also O. Tietze, Zeitschr. prakt. Geologie, 1907, p. 229, on the phosphates of Tunis and Algeria. Tietze gives numerous references to the literature of these deposits. See also C. Pilotti, Pub. Corpo reale delle miniere, Rome, 1908. 526 THE DATA OF GEOCHEMISTRY. Shaler , 1 to account for the nodular phosphates of South Carolina, and it seems to apply equally well to the other phosphorite deposits of the United States. The phosphorites of Tennessee, which have been somewhat ex- haustively studied , 2 furnish an excellent illustration of the several processes, chemical and mechanical, which have taken part in their formation. As interpreted by Hayes and Ulrich, these phosphorites, which are partly Ordovician and partly Devonian, were first laid down in a shallow sea as phosphatic limestones, deriving their phos- phates in all probability from phosphatic brachiopods, such as lingula. Some bones and teeth of Devonian fishes are also found in these beds. The limestones then were subjected to the leaching process, which removed carbonates, leaving a mixture of phosphates, clay, and iron hydroxide. The soil thus formed was again concentrated by mechan- ical washing, the moving waters carrying away the clay and finer silt from the heavier phosphatic nodules. Some phosphates were also dissolved by percolating waters, to be precipitated as a secondary deposit in the underlying limestones, or concentrated in limestone caverns. The phosphorites of Arkansas , 3 * * * * 8 * * which occur in an interval between the Lower Silurian and 11 Lower Carboniferous/' are probably of similar origin to those of Tennessee. At some localities in Arkansas, however, phosphates occur as bands of pebbles in Cretaceous beds, sometimes associated with greensand. This association and also the neighborhood of manganese ores are strongly suggestive of the similar association of these substances in the deep-sea deposits described by Murray and Renard. The same processes were followed in both the ancient and the modern seas. Phosphorites and phosphatic marls are found at many other points in the southeastern parts of the United States, but they probably all originated in the same way, at least so far as chemical processes are concerned. The mechanical transportation of phosphatic silt and its accumulation in hollows or depressions have doubtless happened in 1 Proc. Boston Soc. Nat. Hist., vol. 13, 1870, p. 222, and also later in the introduction to R. A. F. Penrose’s Bull. U. S. Geol. Survey No. 46, 1888. For other matter relative to the South Carolina phosphates, see O. A. Moses, Mineral Resources U. S. for 1882, U. S. Geol. Survey, 1883, p. 504; P. E. Chazal, Sketch of the South Carolina phosphate industry, Charleston, 1904; F. Wyatt, The phosphates of America, New York, 1891; and C. C. H. Millar, Florida, South Carolina, and Canadian phosphates, London, 1892. The earlier literature is well summed up in Penrose’s bulletin. 2 See publications of the U. S. Geol. Survey as follows: C. W. Hayes, Sixteenth Ann. Rept., pt. 4, 1895, p. 610; Seventeenth Ann. Rept., pt. 2, 1896, p. 539; Twentieth Ann. Rept., pt. 6, cont., 1899, p. 633; Twenty- first Ann. Rept., pt. 3, 1901, p. 473; and Bull. No. 213, 1903, p. 418. L. P. Brown, Nineteenth Ann. Rept., pt. 6, cont., 1898, p. 547. E. C. Eckel, Bull. No. 213, 1903, p. 424. The latest discussion, by Hayes and E. O. Ulrich, is given in Geol. Atlas U. S. Folio 95, 1903. See also T. C. Meadows and L. Brown, Trans. Am. Inst. Min. Eng., vol. 24, 1895, p. 582; Hayes, idem, vol. 25, 1896, p. 19; J. M. Safford, Am. Geologist, vol. 18, 1896, p. 261; and W. B. Phillips, Eng. and Min. Jour., vol. 57, 1894, p. 417. 8 See J. C. Branner, Trans. Am. Inst. Min. Eng., vol. 26, 1896, p. 580; also Branner and J. F. Newsom, Bull. Arkansas Agr. Exp. Sta. No. 74, and A. H. Purdue, Bull. U. S. Geol. Survey No. 315, 1907, p. 463. The Devonian black phosphates of the Pyrenees, described by D. Levat (Annales des mines, 9th ser., vol. 15, 1899, p. 4), are also comparable with those of Tennessee and Arkansas. THE DECOMPOSITION OF ROCKS. 527 many instances, but have no chemical significance. In the Florida field, as described by G. H. Eldridge , 1 every step of phosphorite for- mation seems to he represented. Phosphates have been concentrated from limestones and also by mechanical washing; they have formed secondary replacements, and some were deposited from solution. The following analyses were made by George Steiger in the laboratory of the United States Geological Survey, upon material collected by Eldridge. They show the variability of the Florida rock, a variability observed in all other regions. Analyses of Florida phosphates. A. From near Sunnyside, Taylor County. B, C. From Luraville district, Suwanee County. B. From Albion district, Levy County. A B c D Si0 2 3.44 5.36 10. 63 10. 51 Ti0 2 .13 .26 .86 . 58 A1 2 0 3 1.49 5. 41 12. 42 21. 17 Feo(h 1.43 2. 86 2. 90 3. 10 CaO 48. 81 42. 13 30. 93 23. 95 MeO .23 .47 .29 .15 k 2 o Trace. None. . 20 Na 2 0 Trace. None. . 27 | .40 PXL 35. 93 33.37 30. 35 25. 38 co 2 2. 71 2. 15 1. 72 2. 14 so 3 . 10 . 09 . 13 . 15 F 2. 55 2. 10 1 95 1. 42 H 2 0 at 105° . 90 1. 84 1. 27 1. 27 Ignition 1. 98 4. 76 7. 69 10.35 Less O 99. 70 1.05 100. 80 .88 101. 61 .82 100. 57 .60 Organic C 98. 65 99. 92 .18 100. 79 .12 99. 97 .22 A new phosphate field, probably the largest known, is in the States of Idaho, Wyoming and Utah. At the date of writing it is still under investigation . 2 The subjoined partial analyses of rock from this region are also by Steiger. 1 Trans. Am. Inst. Min. Eng., vol. 21, 1893, p. 196. See also W. B. M. Davidson, idem, p. 139. Eldridge cites a number of incomplete analyses of Florida phosphates by T. M. Chatard, all made in the Survey laboratory. Other papers on the Florida phosphates by E. T. Cox, G. M. Wells, andE. W. Codington, may be found in Trans. Am. Inst: Min. Eng., vol. 25, 1896, pp. 36, 163, 423; also one by N. A. Pratt, in Eng. and Min. Jour., vol. 53, 1892, p. 380. See also E. H. Sellards, Third Ann. Rept. Florida State Geol. Survey, 1909-10, and G. C. Matson, Bull. U. S. Geol. Survey No. 604, 1915. 2 See report by H. S. Gale and R. W. Richards, Bull. U. S. Geol. Survey No. 430, 1910, p. 457; and E. Blackwelder, idem, p. 537. Other reports appear in Survey Bulls. Nos. 470, 530, 543, and 580. Earlier reports by F. B. Weeks and W. F. Ferrier are in Bulls. 315 and 340. 528 THE DATA OF GEOCHEMISTKY. Analyses of western phosphates. A. 2 \ miles west of Cokeville, Wyoming. B. Dunellan lode, 8 miles southwest of Sage, Utah. C. Elsinore claim, 3 miles west of Devils Slide, Utah. D. Eight miles southeast of Georgetown, Idaho. A B C D Insoluble 2. 62 1. 82 9.40 10. 00 Si0 2 .46 .30 Undet. None. A1 2 0 3 . 97 . 50 .90 .89 Fe 2 0 3 .40 .26 .33 . 73 MgO .35 .22 .26 .28 CaO 48. 91 50. 97 46.80 45. 34 N a 2 0 . 97 2. 00 2. 08 1. 10 K 2 0 .34 .47 .58 .48 H 2 0- 1. 02 .48 . 61 1. 04 h 2 o+ 1. 34 . 57 . 75 1. 14 C0 2 : 2.42 1. 72 2. 14 6. 00 33. 61 36. 35 32. 05 27. 32 so 3 2. 16 2. 98 2.34 1. 59 F .40 .40 .66 . 60 Cl Trace. Trace. Trace. Trace. 95. 97 99.04 98. 90 96. 51 Note. — For other data on American phosphates, see B. A. F. Penrose, Bull. U. S. Geol. Survey No. 46, 1888, and also the following publications: Phosphates and marls of Alabama, E. A. Smith, Bull. Geol. Survey Alabama No. 2, 1892; and W. C. Stubbs, Mineral Besources U. S. for 1883-84, U. S. Geol. Survey, 1885, p. 794. The Alabama localities yield phosphatic marls and greensands, of Cretaceous age. S. W. McCallie, Phosphates and marls of Georgia: Bull. Geol. Survey Georgia No. 5-A, 1896. D. T. Day, North Carolina phosphates: Mineral Besources U. S. for 1883-84, U. S. Geol. Survey, 1885, p. 788. M. C. Ihlseng, Phosphates of Juniata County, Pennsylvania: Seventeenth Ann. Bept. U. S. Geol. Survey, pt. 3, 1896, p. 955. For phosphorite in Japan, see K. Tsuneto, Chem. Zeitung, vol. 23, 1899, pp. 800, 825. This phosphate occurs in Miocene sandstone and contains some glauconite. Good analyses are given. On phosphate rock in New Zealand, see A. B. Andrew, Trans. New Zealand Inst., vol. 38, 1905, p. 447. On Christmas Island, Indian Ocean, E. W. Skeats, Bull. Mus. Comp. Zool., vol. 42, 1903, p. 103. On nodules in eastern Thuringia, J. Lehder, Neues Jahrb., Beil. Band 22, 1906, p. 48. On French phosphates, A. Nantier, Compt. Bend., vol. 108, 1889, p. 1174; and H. Lasne, Bull. Soc. geol. France, 3d ser., vol. 18, 1889-90, p. 441. On Bussian phosphorites, W. Tschirwinski, Neues Jahrb., 1911, Band 2, p. 51. See also a work by C. Elschner, Die corallogene Phosphat- Inseln Austral-Oceaniens, Liibeck, 1913; and an address by J. J. H. Teall, Proc. Geologists’ Assoc., 1900, p. 369. FERRIC HYDROXIDES. An important class of products, derived from the decomposition of rocks, is that which includes the oxides and hydroxides of iron and manganese. The residual deposit of ferric hydroxide, known as lat- erite, has already been described; other modes of occurrence remain to be considered now. THE DECOMPOSITION OF ROCKS. 529 Several hydroxides of iron have been given definite rank as mineral species. They are : Turgite 2Fe 2 0 3 .H 2 0. Contains 94.6 per cent Fe 2 0 3 . Goethite Fe 2 0 3 .H 2 0. Contains 89.9 per cent Fe 2 0 3 . Limonite 2Fe 2 0 3 .3H 2 0. Contains 85.5 per cent Fe 2 0 3 . Xanthosiderite Fe 2 0 3 .2H 2 0. Contains 81.6 per cent Fe 2 0 3 . Limnite Fe 2 0 3 .3H 2 0. Contains 74.7 per cent Fe 2 0 3 . Of these only one, goethite, is crystalline; the others are amorphous, and all sorts of mixtures between them are likely to occur. 1 They are also often admixed with siderite, FeC0 3 , which is itself an impor- tant ore of iron. .Other impurities are sand, clay, calcium and mag- nesium carbonates, aluminum hydroxides, manganese compounds, phosphates, such as vivianite, organic matter, etc. Some of the rarest metals — like gallium, indium, thallium, and rubidium — are also very commonly present in ores of this class, but only in minute traces. They have been detected spectroscopically. 2 From an eco- nomic point of view, all of these minerals are grouped together as limonite, for the reason that that species is by far the most abundant and forms large ore bodies. The processes by which deposits of ferric hydroxide are produced have already been partly indicated. Residual deposits may be formed as in the case of laterite, or as represented by the gossan caps over bodies of sulphide ores. Great outcrops of such ores, especially of pyrite or chalcopyrite, are often altered to a considerable depth into masses of porous limonite. Pseudomorphs of limonite after pyrite are exceedingly common. 3 When sulphides containing iron are thus oxidized, some iron is removed in solution as sulphate, from which it may be precipitated later as hydroxide. Carbonated waters also extract iron from silicate rocks, or from disseminated magnetite, again forming solutions from which limonite may be deposited. The rusty sediments around chalybeate springs are illustrations of the latter process. Organic acids also assist in the solution of ferrous compounds, and furnish to swamp waters the material from which bog iron ores are formed. Stagnant swamp waters are often covered by iridescent films of ferric hydroxide, produced by atmospheric oxi- dation of ferrous carbonate, in visible exemplification of the process described above. The following analysis of a spring water, which rises under a layer of ore at Ederveen, Netherlands, is cited by Van Bemmelen 4 to indicate the source from which the iron oxides were derived. The figures refer to milligrams per liter. 1 Perhaps the hydrogoethite, 3 F 6203 . 4 H 20 , of P. A. Zemjatschensky (Zeitschr. Kryst. Min., vol. 20, p. 185) is such a mixture. 2 See W. N. Hartley and H. Ramage, Jour. Chem. Soc., vol. 71, 1896, p. 533. 3 On the pyritic origin of iron ores see H. M. Chance, Eng. Min. Jour., vol. 86, 1908, p. 408, and Trans. Am. Inst. Min. Eng., vol. 39, 1909, p. 522. Chance regards this origin as very general. 4 J. M. van Bemmelen, C. Hoitsema, and E. A. Klobbie, Zeitschr. anorg. Chemie, vol. 22, 1900, p. 337. Analysis by G. Moll van Charante. The phosphoric acid of the water goes to the formation of vivianite. 97270°— Bull. 616—16 34 530 THE DATA OF GEOCHEMISTRY. Analysis of spring water at Ederveen, Netherlands. Ca.... Mg... Fe... Mn... K.... Na... ai 2 0 3 Cl.... 107.6 S0 4 .... 5.6 h 3 po 4 .. 19.6 co 3 11.4 Si0 2 0.9 Organic 10.0 3.3 15.2 0.9 10.9 207.6 18.0 56.0 467.0 From waters of this kind deposits are formed under swamps and bogs as an impervious hardpan, and also frequently in lakes or ponds. Their formation is sometimes very rapid, and instances are cited by A. Geikie 1 of Swedish lakes in which layers of bog ore several inches thick accumulated in the course of 26 years. According to N. S. Shaler, 2 bog ores are most abundant along the margins of swamps, and often wanting at the centers. When the waters deposit their load in presence of much carbonic acid or decaying organic mat- ter, the carbonate, siderite, is laid down; but where the air has free access limonite is produced. In muddy waters the silt goes down with the iron compounds, forming clay ironstone; and the black band ores of the coal measures represent what was once a carbonaceous mud. 3 In many cases the decomposition of ferrous carbonate solu- tions is effected or aided by the so-called “ iron bacteria,” which absorb the iron and redeposit it later as ferric hydroxide. 4 These organisms are found in the ground water and the soil. From sulphate solutions the iron may be precipitated by carbonates, phosphates, or by organic matter contained in admixed waters. Ferrous sulphate first oxidizes, yielding ferric hydroxide and insoluble basic salts. Beds of limonite sometimes represent a different mode of origin from those just described. R. A. F. Penrose 5 suggests that in some cases limonite has been derived from glauconite by a process of alter- ation. It may be formed by pseudomorphous replacement of lime- stones, when solutions of iron compounds percolate through them. 6 Ferriferous limestone, also, may yield residuary deposits of limo- 1 Text-book of geology, 4th ed., p. 187. 2 Tenth Ann. Rept. U. S. Geol. 'Survey, pt. 1, 1890, p. 305. 3 The literature of these ores is very abundant and voluminous. See especially F. M. Stapfl, Zeitschr. Deutsch. geol. Gesell., vol. 18, 1865, p. 86; J. S. Newberry, School of Mines Quart., vol. 2, 1880, p. 1; H. Sjogren, Neues Jahrb., 1893, Band 2, p. 273, ref.; J. H. L. Vogt, Zeitschr. prakt. Geologie, 1894, p. 30, and 1895, p. 38; G. Reinders, Verhandl. Akad. Wet. Amsterdam, sec. 2, vol. 5, No. 5; A. Gaertner, Arch. Ver. Mecklenburg, vol. 51, 1897, p. 73; and J. M. van Bemmelen, Zeitschr. anorg. Chemie, vol. 22, 1900, p. 313. On the origin of bog iron ore see also E. J. Moore, Econ. Geology, vol. 5, 1910, p. 528. 4 See Van Bemmelen, loc. cit.; G. Tolomei, Zeitschr. anorg. Chemie, vol. 5, 1894, p. 102; and authorities cited by C. R. Van Hise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, p. 826. Also E. M. Mumford, Jour. Chem. Soc., vol. 103, 1913, p. 645. 5 Ann. Rept. Geol. Survey Arkansas, vol. 1, 1892, p. 124. See also L. Cayeux, Compt. Rend., vol. 142, 1906, p. 895. 6 See J. P. Kimball, Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 231. See also C. W. Hayes, Trans. Am. Inst. Min. Eng., vol. 30, 1900, p. 403; Hayes and E. C. Eckel, Bull. U. S. Geol. Survey No. 213, 1903, p. 233; and S. W. McCallie, Bull. No. 10-A, Geol. Survey Georgia, 1900, p. 19, on the iron ores of that State. THE DECOMPOSITION OF ROCKS. 531 nite, the oxidation of ferrous carbonate and the solution of calcium carbonate going on at the same time. The Clinton ores are regarded by A. F. Foerste 1 as formed by the replacement of lime in bryozoan remains ; although C. H. Smyth 2 has shown that in the oolitic varie- ties each spherule is made up of concentric layers around a nucleus of quartz. He argues that the ores were deposited in the shoal waters of the Silurian sea, presumably upon a sandy bottom. The essential process, however, precipitation from solution, whether by oxidation, by organic matter, or by carbonate of lime, is the same in all cases. The ironVas dissolved, in the first instance, from ferruginous rocks, and then thrown down by any one of the several reactions indicated. The iron ores of eastern Cuba 3 are essentially lateritic in character, being residues from the decomposition of serpentine, and the same is true of the Clealum ores in the State of Washington . 4 The precipitated hydroxides of iron vary much in character and appearance, and their exact chemical nature, despite the plausible formulae assigned to some of the minerals, is by no means clear. In color they range from yellow through various shades of brown and red, and in texture they differ as widely. J. M. van Bemmelen 5 regards them as colloidal complexes of ferric oxide and water, to which chemical formulae are not properly applicable; and the same view is held by him concerning the humus acids and the so-called ferrohumates . 6 According to P. Nicolardot , 7 however, whose inves- tigation is most recent, ferric hydroxide exists in at least six modi- fications which differ in their physical and chemical properties and in their content of water. They are all, he says, polymers of the simplest hydroxide. From what has been said in the preceding paragraphs, it is evident that the composition of sedimentary iron ores must range between widely separated limits. They may be mainly ferrous carbonate, either crystalline or amorphous, or principally limonite with all sorts of admixtures of other substances. The following analyses of bog ore, “raseneisenstein,” from Ederveen, are given in the memoir by 1 Am. Jour. Sci., 3d ser., vol. 41, 1891, p. 28. 2 Idem, vol. 43, 1892, p. 487. 3 See A. C. Spencer, Bull. U. S. Geol. Survey No. 340, 1908, p. 318; C. M. Weld, Bull. Am. Inst. Min. Eng. No. 32, 1909, p. 749; C. K. Leith and W. J. Mead, idem, No. 51, 1911, p. 217. The last bulletin con- tains five other papers on the Cuban ores. 4 See G. O. Smith and B. Willis, Trans. Am. Inst. Min. Eng., vol. 30, 1901, p. 356. 6 Rec. trav. chim., vol. 7, 1888, p. 106; vol. 18, 1899, p. 86; Zeitschr. anorg. Chemie, vol. 20, 1899, p. 185, vol. 22, 1900, p. 313, vol. 42, 1904, p. 281. Also J. M. van Bemmelen and E. A. Klobbie, Jour, prakt. Chemie, 2d ser., vol. 46, 1892, p. 529. 6 See also W. Spring, Bull. Acad. roy. sci. Belgique, 3d ser., vol. 34, 1897, p. 578, on the relations of humus to iron in natural waters, already cited on p. 506, ante. The same subject has recently been discussed by O. Aschan, Zeitschr. prakt. Geologie, vol. 15, 1907, p. 56. 7 Annales chim. phys., 8th ser., vol. 6, 1905, p. 334. Nicolardot cites many references to former investiga- tions upon the precipitated hydroxides. See also Otto Ruff, Ber. Deutsch. chem. Gesell., vol. 34, 1901, p. 3417. 532 THE DATA OF GEOCHEMISTRY. J. M. van Bemmelen, C. Hoitsema, and E. A. Klobbie. 1 These varia- tions are shown in ore from a single locality, and the substances men- tioned are mostly crystalline. The Fe 2 0 3 represents the amorphous variety. Analyses of bog ore. A. By G. Reinders. B. By E. A. Klobbie. C. By F. M. Jager. D. By C. H. Kettner. A B c D Fe 2 0 3 10. 58 2. 49 8.0 36. 49 FeC0 3 20. 77 37. 70 30? 6 6. 12 MnCOg 4.04 .67 2. 91 CaC0 3 2. 27 4. 46 4.0 4. 10 MgCO, . 17 .10 .21 Fe,(PO.)o 4. 30 2.9 5. 47 Fe /// P0 4 1. 75 1. 76 CaS0 4 .07 A1 2 0 3 .93 .21 .60 KC1 .03 Trace. Trace. NaCl .23 Trace. Trace. Soluble Si0 2 .82 } 49.1 6. 30 Sand } 49. 30 50. 02 19. 30 Organic matter 1. 57 .03 1.8 1. 20 H 2 0 at 100° 3. 68 .95 12. 10 H 2 0, ignition 2. 06 1. 12 } 3. 3 J 4.00 100. 00 100. 32 99.7 100. 56 The subjoined analyses of limonitic bog iron from Mittagong, Australia, are cited by A. Liversidge. 2 They are quite different from those shown in the preceding group. Analyses of Australian bog ores. E F G H Fe 2 0 3 68. 37 57. 61 74. 71 65. 84 A1 2 0 3 4. 63 24. 30 3. 04 4. 49 MnO Trace. 6. 41 Trace . 1. 40 MgO Trace. Trace. .43 .48 CaO Trace. Trace. Trace. Trace. Si0 2 14. 10 10. 10 14. 27 Trace. Trace. Trace. .25 so, Trace . Trace. Trace. . 11 H 2 0, hygroscopic 3. 00 1. 20 2. 20 2. 30 H 2 0, combined 9. 72 10. 38 9. 70 10. 86 99. 82 99. 90 100. 18 100. 00 1 Zeitschr. anorg. Chemie, vol. 22, 1900, p. 319. 2 Minerals of New South Wales, p. 99. The analyses were made by the "government analyst/ THE DECOMPOSITION OF ROCKS. 533 MANGANESE ORES. Manganese, like iron, is also dissolved out from the crystalline rocks, in which it is almost invariably present, and by the same agen- cies. It may go into solution as sulphate, or as carbonate, to be rede- posited as carbonate, oxide, or hydroxide, under various conditions and in a variety of forms. A deposition as dioxide, hydrous or anhydrous, is very common and is often seen in the dendritic infiltra- tions which occur in many rocks and in the black coatings which some- times cover river pebbles or surround manganiferous mineral springs. Nodules consisting chiefly of manganese dioxide are abundant on the bottom of the deep sea, as described in a previous chapter, 1 and similar nodular forms have been observed that were of recent terrestrial origin. May Thresh 2 discovered small hard black nodules resembling seeds in the bowlder clay of Essex, England; and similar bodies were found by W. M. Doherty 3 on the surface of the ground in Australia. Manganese differs from iron, however, in its degrees of oxidation. Ferrous oxide and hydroxide, as such, are unknown in nature; but manganosite, MnO, and pyrochroite, Mn(OH) 2 , are well-known min- erals. Manganite, Mn 2 0 3 .H 2 0, corresponds in type with goethite and diaspore; and hausmannite, Mn 3 0 4 , is the equivalent of magnet- ite, although the two species are crystallographic ally unlike. Polia- nite and pyrolusite, two crystallized forms of the dioxide, Mn0 2 , are not matched by any compound of iron, and this oxide forms the chief manganese ore. Braunite, to which the formula 3Mn 2 0 3 .MnSi0 2 is assigned, is also a crystallized mineral, but its composition, as shown by analyses, is somewhat variable. The hydrous psilomelane, of uncertain constitution, is often associated with pyrolusite, and allied to it are many varieties which have received distinct names. These latter ores are amorphous, 4 and probably represent colloidal complexes, such as were mentioned in connection with the sedimen- tary ores of iron. The following analyses represent substances in this class, ranging from the crystalline pyrolusite to the earthy wad, or bog manganese, the cupriferous lampadite, etc. 1 See p. 134, ante. 2 Jour. Chem. Soc., vol. 82, pt. 2, ref. 567, 1902. 3 Rept. Australasian Assoc. Adv. Sci., 1898, p. 339. 4 According to A. Gorgeu (Bull. Soc. min., vol. 13, 1890, p. 27), the variety known as wad is sometimes crystallized. 534 THE DATA OF GEOCHEMISTRY. Analyses of manganese ores. A. Pyrolusite, Crimora mine, Augusta County, Virginia. Analysis by J. L. Jarman, Am. Chem. Jour., vol. 11, 1889, p. 39. B. Psilomelane, near Silver Cliff, Colorado. Analysis by W. F. Hillebrand, Bull. U. S. Geol. Survey No. 220, 1903, p. 22. C. Psilomelane, Roman&che, France. Analysis by A. Gorgeu, Bull. Soc. min., vol. 13, 1890, p. 23. Partly recalculated from the original. D. Wad, Romaneche, France. Analysis by Gorgeu, idem, p. 27. Partly recalculated. Gorgeu gives many analyses of natural oxides and hydroxides of manganese. See Bull. Soc. min., vol. 13, 1890, p. 21; vol. 16, 1898, pp. 96, 133. Also Bull. Soc. chim., 3d ser., vol. 9, 1893, pp. 496, 650. E. Varvicite, Austinville, Wythe County, Virginia. Analysis by P. H. Walker, Am. Chem. Jour., vol. 10, 1880, p. 41. F. Lampadite, or lepidophaeite, Kamsdorf, Thuringia. Analysis by Jenkins, for A. Weisbach, Neues Jahrb., 1880, Band 2, p. 109. This mineral shows exceptionally high hydration. A B c D E F Mn0 2 95. 88 76. 18 5. 71 .34 1.81 66. 88 8. 22 1. 45 64. 98 7. 27 } 1.10 .30 Trace. 68. 86 7. 51 } 2.23 58. 77 9. 59 MnOl Fe 2 0 3 .62 A1 2 0 3 PbO } .10 CuO 11. 48 NiO .22 .27 CoO Trace. 2. 80 .83 Trace. Trace. 1. 65 15. 45 Trace. Trace. .80 } 5.00 .05 .60 ZnO Trace. .40 16. 20 .20 } .10 } 4.65 Trace. 1. 50 CaO .09 BaO 14. 42 MgO .29 3. 46 .81 1. 41 3. 94 k 2 o .18 .23 } 2.08 Na 2 0 : HoO- } 5.08 } 21.05 h 2 o+ p 9 o, ; A&jOj Sb 2 0 5 .12 CaS0 4 .40 .80 1. 40 Si0 2 2. 30 .25 .15 1. 98 Insoluble .29 99. 86 100. 00 100. 10 99. 80 100. 08 100. 89 Asbolite is an earthy psilomelane containing much cobalt, which is a common impurity in manganese ores. Barium, as shown in the analyses, is also a frequent constituent of them. The crystalline hollandite, described by L. L. Fermor , 1 contains both barium and iron, in addition to the manganese. Coronadite, an oxide of man- ganese and lead, described by W. Lindgren and W. F. Hillebrand , 2 is a mineral of similar character. The minerals of this class are commonly interpreted as manganites, that is, as salts of manganous acid. Their definiteness is questionable. These sedimentary ores, and the similar ores produced by the altera- tion of manganiferous minerals, have diverse origins. F. R. Mallet 3 1 Rec. Geol. Survey India, vol. 36, 1908, p. 295. Vol. 37 of the Memoirs of the same Survey, 1909, in four parts, is an exhaustive monograph by Fermor on the manganese ores of India. In it he describes as new species three other mixed oxides of manganese and iron, to which he gives the names vredenburgite, sita- parite, and beldongrite. * Am. Jour. Sci., 4th ser., vol. 18, 1904, p. 448. 3 Rec. Geol. Survey India, vol. 12, 1879, p. 99; vol. 16, 1883, p. 116. THE DECOMPOSITION OF ROCKS. 535 has observed lateritic pyrolusite or psilomelane as an integral portion of some Indian laterites. The manganese ores of Queluz, Brazil, according to O. A. Derby, 1 are residual deposits derived from rocks in which manganese garnet was the most constant and characteristic silicate. Bog or swamp deposits are common, and so, in short, the sedimentary and residual ores of iron are very fully paralleled. Only the gossan ores have no true manganic equivalent. The sulphides of manganese are relatively rare, and their oxidation products occur only in sporadic cases. 2 Manganese and iron, then, are dissolved out from the rocks by the same reagents, at the same time, and in essentially the same way. They are redeposited under similar conditions, but not absolutely together, for a separation is more or less perfectly effected. True, nearly all limonites contain some manganese, and nearly all psilome- lanes contain some iron; but in very many cases the ores of the two metals are thrown down separately. How is the separation brought about? To this question various answers have been suggested, but only two or three of them have any modern significance. According to C. R. Fresenius, 3 who has analyzed the deposits formed by the warm springs of Wiesbaden, the iron is precipitated first as ferric hydroxide. The manganese of the water remains in solution much longer as bicarbonate, and is finally laid down as car- bonate as an impurity in calcareous sinter; that is, solutions of manganese carbonate are more stable than solutions of ferrous car- bonate, and the manganese is therefore carried farther. A partial separation of the two metals, from the same solution, is thus effected. The thermochemical arguments of L. Dieulafait 4 * * * 8 are quite in har- mony with the foregoing observations, and, indeed, help to explain them. These arguments rest upon the general principle that when several reactions may conceivably take place, that one which is attended by the greatest evolution of heat will occur. The thermo- chemical equations used by Dieulafait are as follows: 2FeO + O = Fe 2 0 3 + 26.6 Cal. 2MnO + 20 = 2Mn0 2 + 21.4 Cal. 1 Am. Jour. Sci., 4th ser., vol. 12, 1901, p. 18. 2 A very full monograph on manganese ores, by R. A. F. Penrose, forms vol. 1 of the Annual Report of the Arkansas Geological Survey for 1890. See also an article by Penrose, Jour. Geology, vol. 1, 1893, p. 356. J. D. Weeks has reported on the manganese deposits of the United States in Mineral Resources U. S. for 1892, U. S. Geol. Survey, 1893, p. 171. T. L. Watson (Trans. Am. Inst. Min. Eng., vol. 34, 1904, p. 207) has described the manganese ores of Georgia. The manganese ore of Golconda, Nevada, which contains tungsten, is interpreted by Penrose (Jour. Geology, vol. 1, 1893, p. 275) as probably a spring deposit. On the carbonate ores of Las Cabesses, in the Pyrenees, see C. A. Moreing, Trans. Inst. Min. Met., vol. 2, 1894, p. 250. See also J. H. L. Vogt, Zeitschr. prakt. Geologie, 1906, p. 217, for an elaborate paper on bog man- ganese. Bull. 427 of the U. S. Geol. Survey, 1910, is a report by E. C. Harder on the manganese ores of the United States. 8 Cited by G. Bischof, Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 1, p. 540. * Compt. Rend., vol. 101, 1885, pp. 609, 644, 676. 536 THE DATA OF GEOCHEMISTRY. Hence, if oxygen acts on a mixture of FeO and MnO, or upon sub- stances equivalent to them,. ferric oxide will form first and be the more stable. FeO + C0 2 = FeCOg + 5.0 Cal. MnO + C0 2 = MnCOg + 6.8 Cal. When carbon dioxide unites with these oxides, then, the manganese compound will form first and be the more stable. If oxygen and carbon dioxide act together in considerable excess, Fe 2 0 3 and Mn0 2 will both be formed; but if they act slowly, in small quantities, the oxygen will go to produce Fe 2 0 3 , and MnC0 3 can be generated at the same time. The manganese carbonate, being somewhat soluble, may then be separated from the ferric oxide by leaching, either to be deposited as carbonate, or perhaps to be oxidized to Mn0 2 and C0 2 later. In the last of Dieulafait’s papers he gives the heat of formation of several manganese compounds: Mn + S, 22.6 Cal. Mn + O, 47.4 Cal. Mn + 0 + C0 2 , 54.2 Cal. Mn + 0 2 , 58.1 Cal. From these figures it appears that the dioxide is the most stable compound in the series; it is therefore the easiest formed, and is the principal manganese ore. The thermochemical and geological data are in complete harmony. It is more than probable, as F. P. Dunnington 1 has shown, that manganese sulphate plays an important part in the separation of the two metals. He has proved experimentally that acid solutions of ferrous sulphate, such as are formed by the oxidation of pyrites, will dissolve manganese oxides to a very marked extent. At the same time ferric sulphate and ferric hydroxide, under favorable conditions, may also be formed. In contact with manganese carbon- ate, in presence of air, ferrous sulphate is rapidly oxidized, pro- ducing manganese sulphate, ferric hydroxide, and carbon dioxide. Both sulphates of iron react with calcium carbonate, and the ferric salt generates carbon dioxide, ferric hydroxide, and calcium sul- phate. Manganese sulphate acts but little, if at all, upon calcium carbonate, if protected from access of air; in presence of air, how- ever, manganese oxide is gradually formed. From these reactions it is easy to see that limestones may be impor- tant factors in the separation of manganese and iron. Where sul- phates of the two metals percolate through limestones, the iron will be by far the more easily precipitated, while the manganese will remain in solution until it is exposed to both air and calcium carbon- ate simultaneously. Am. Jour. Sci., 3d ser., vol. 36, 1888, p. 175. CHAPTER XIII. SEDIMENTARY AND DETRITAL ROCKS. SANDSTONES. By pressure, or by the injection of cementing materials, the prod- ucts of rock decomposition may be reconsolidated. From the sands sandstones are formed; from the clays, shales are derived; and cal- careous deposits yield the limestones. These rocks shade into one another, through intermediate gradations, and exhibit the same varia- tions in composition that are observed in sands and soils. Their classification depends upon their typical forms, and their modifica- tions are indicated by a simple nomenclature. Such terms as cal- careous sandstone, argillaceous limestone, and sandy shale explain themselves, for they are clearly descriptive. Although not rigorous, they are sufficient for most practical purposes. 1 A sandstone differs chemically from a sand chiefly in the addition of a cementing substance. This is furnished by percolating waters, or else, in certain cases, by the slight solution of the moist surfaces of mineral particles in contact with one another. Any substance which the waters can deposit in a relatively insoluble condition may serve as a cement. Such substances as silica, calcium carbonate, hydroxides of iron and aluminum, calcium sulphate, phosphate, and fluoride, barium sulphate, etc., fulfill this condition. Clay and bitu- minous substances also act as cementing materials. The additions thus made to a sand may be small in amount or even very large, some- times equaling in quantity the cemented particles. Such an extreme case is furnished by the well-known Fontainebleau calcites, which have crystallized around sand and contain sometimes 50 per cent of calcium carbonate. A. von Morlot 2 reports crystals from this locality containing 58 per cent of sand, and others with as high as 95 per cent. Analogous crystals from the Badlands of South Dakota, de- scribed by S. L. Penfield and W. E. Ford, 3 contain approximately 40 per cent of calcite to 60 per cent of sand. These are mixtures of sand and calcite in which £he crystalline form of the latter has been perfectly developed. Gypsum crystals containing sand up to 48.58 per cent have been found on the Astrakhan steppe, according to B. Doss, 4 who also mentions gypsiferous sandstones. Crystals of 1 On a classification of the sedimentary rocks, see A. W. Grabau, Am. Geologist, vol. 33, 1904, p. 228. 2 Haidinger’s Ber., vol. 2, 1846-47, p. 107. 3 Am. Jour. Sci., 4th ser., vol. 9, 1900, p. 352. 4 Zeitschr. Deutsch. geol. Gesell., vol. 49, 1897, p. 143. 537 538 THE DATA OF GEOCHEMISTRY. barite inclosing sand are also well known. J. E. Pogue 1 has described crystallized barite inclosing 44 to 53 per cent of sand from the oasis of Kharga, Egypt; and H. W. Nichols 2 reports similar material found in Oklahoma. As a rule, however, the cementing material of a sand- stone is subordinate. Between a sand and a sandstone the difference in composition is generally slight and may be almost inappreciable. When silica serves as the cementing substance, it may assume either the amorphous or the crystalline form. In the latter case the quartz fragments often exhibit a secondary enlargement and become the nuclei of distinct quartz crystals. 3 As amorphous silica it simply fills the interstitial spaces of the rock and binds the sand grains together. These spaces or pores vary in magnitude, and may make up a considerable portion of the total volume of a rock. According to G. F. Becker, 4 the interstitial space in a sandstone made up of closely packed spherical grains amounts to 25.96 per cent. C. R. Van Hise 5 estimates the minimum pore space at 24 per cent, and claims that it may be much greater. The character of the rock pro- duced by the consolidation of such a bed will obviously depend upon the extent to which the cementing material has filled the interstitial spaces. One sandstone is loosely compacted, another is solid, and by thorough silicification the rock may become transformed into a hard, vitreous quartzite. In an ordinary sandstone the fracture is around the grains; in a quartzite it is just as likely to be across them. After silica, and often with silica, the commonest cements of sand- stone consist of carbonates. 6 Calcium carbonate is the most abun- dant salt derivable from percolating waters, and is easily deposited therefrom; hence its frequency in the sediments, even in those which were not laid down in proximity to limestones. Calcareous sandstones are exceedingly common, and at the other end of the series arena- ceous limestones are not rare. The following analysis of a greenish sandstone from Lohne, Westphalia, by W. von der Marck, 7 may illustrate the complexity of these mixtures. 1 Proc. U. S. Nat. Mus., vol. 38, 1910, p. 17. Pogue gives a good list of other occurrences. 2 Pub. No. Ill, Field Columbian Mus., 1906, p. 31. s See A. Knop, Neues Jahrb., 1874, p. 281; A. S. Tomebohm, Neues Jahrb., 1877, p. 210; H. C. Sorby, Quart. Jour. Geol. Soc., vol. 36, 1880, Proc., p. 46; A. A. Young, Am. Jour. Sci., 3d ser., vol. 34, 1882, p. 47; R. D. Irving and C. R. Van Hise, Buil. U. S. Geol. Survey No. 8, 1884; Irving, Fifth Ann. Rept. U. S. Geol. Survey, 1885, p. 218. “Crystallized sands” from Peru are mentioned by L. Crosnier, Annales des mines, 5th ser., vol. 2, 1852, p. 5; and A. Daubree (Etudes synth<5tiques de geologie exp6rimentale, pp. 226-230) cites a number of European examples. m * Mon. U. S. Geol. Survey, vol. 13, 1888, p. 399. s Idem, vol. 47, 1904, p. 863. 6 Calcium carbonate, up to nearly 30 per cent, is the cementing substance of the sandstone reefs found on the coast of Brazil. See the important monograph by J. C. Branner, which forms vol. 44 of Bull. Mus. Comp. Zool., 1904. Branner mentions similar reefs in the Levant. 7 Verhandl. Naturhist. Ver. preuss. Rheinlande u. Westfalens, vol. 12, 1855, p. 269. Many other, similar analyses are given. G. Bischof (Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 3, pp. 137-149) gives abundant data upon the cementing materials of sandstones. In analyses of these rocks it is commonly assumed that the portion soluble in hydrochloric acid belongs wholly to the cement. This is probably true in most cases, but not always. Soluble minerals may occur in a sandstone among its granular components. SEDIMENTARY AND DETRITAL ROCKS. 539 Analysis of sandstone from Westphalia. 39. 50 7. 23 7. 54 3. 90 .82 2. 12 36. 65 .91 .03 .62 99. 32 In this analysis calcium phosphate appears among the cementing substances, and many other examples of its occurrence under like con- ditions are known. Phosphatic sandstones from Perry County, Ten- nessee, have been described by C. W. Hayes, 1 and also a phosphatic breccia. In these rocks the calcium phosphate forms the matrix of the sand grains. In a brown sandstone from Kursk, Russia, C. Claus 2 found 13.60 per cent of P 2 0 5 , equivalent to 22.64 of Ca 3 P 2 0 8 . In the same sandstone 4.98 per cent of calcium fluoride was also present. Calcium fluoride has also been reported by W. Mackie 3 as a cement- ing material in a Triassic sandstone from Elginshire, Scotland — in one specimen as much as 25.88 per cent. These figures, of course, represent exceptional samples — concentrations, so to speak; in ordi- nary cases the cementing compounds are found in small amounts. Barium sulphate has repeatedly been observed as a cement in sandstones. F. Clowes 4 has described specimens containing from 28.20 to 60.06 per cent of BaS0 4 . Clowes suggests that the barite was probably formed in situ, by double decomposition between barium carbonate and sulphates contained in percolating waters. Barium has often been detected in the waters of mineral springs. 5 6 The b ary tic sandstones, so far as they have been described, are remarkably durable, because of the insoluble character of the cement. Calcareous sandstones are easily disintegrated by weathering, for the carbonates are readily dissolved by atmospheric waters. Apart from the cements, sandstones vary in composition exactly as do the sands. A sandstone may be nearly pure quartz, or quartz and feldspar, or micaceous, or glauconitic, and it can exhibit any texture from the finest to the coarsest. Textural differences, how- ever, do not concern the chemist. From a chemical point of view it Soluble portion. Insoluble portion f CaC0 3 . . MgC0 3 . FeC0 3 . Ca 3 P 2 O g Fe 2 0 3 . . A1 2 0 3 . . fSi0 2 .... LA1 2 0 3 ... k 2 o.... h 2 o.... 1 Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1896, pp. 527, 539. 2 Jahresb. Chemie, 1852, p. 980. 3 Rept. Brit. Assoc. Adv. Sci., 1901, p. 649. See also O. Miigge, Centralbl. Min., Geol. u. Pal., 1908, p. 33. 4 Proc. Roy. Soc., vol. 46, 1889, p. 363; vol. 64, 1899, p. 374. See also W. Mackie, Rept. Brit. Assoc. Adv. Sci., 1901, p. 649; C. B. Wedd, Geol. Mag., 1899, p. 508; and C. C. Moore, Proc. Liverpool Geol. Soc., vol. 8, 1898, p. 241. Moore gives several good analyses of sandstones. In some of them small amounts of cobalt and nickel were found. 6 See ante, p. 204. See also R. Delkeskamp, Notizbl. Ver. Erdkunde, 4th ser., Heft 21, 1900, p. 47. 540 THE DATA OF GEOCHEMISTRY. is immaterial whether the sand grains are coarse or fine, rounded or angular. Such rocks as conglomerates, breccias,- arkoses, gray- wackes, etc., have no distinct chemical peculiarities; they are made up of detrital material, and vary from their parent formations only in the extent to which their component fragments have been decom- posed and in the nature of their cementing substances. Any sand or detritus may be reconsolidated by any one of the cements above mentioned. When a mixture of sand and clay consolidates, it may form an argillaceous sandstone or a sandy shale, according to the relative proportions of the two ingredients. In such a sandstone the colloidal substances of the admixed clay appear to act as binders, their function being somewhat different from that of the cements deposited by solutions. Their binding power is probably, in most cases, reinforced by the addition of true cements, usually either calcium carbonate or silica. By secondary reactions, due to addi- tions of this kind, the clay substances may be transformed into other things, as shown in the graywacke of Hurley, Wisconsin. 1 This is a detrital rock, which originally consisted largely of quartz and feldspar, with a little hornblende, and dark fragments of older rock material, held together by clay. In the graywacke the clay has been transformed into what is principally a chlorite, with sec- ondary quartz and some other minor minerals. The cement, which was at first amorphous, is now entirely crystalline. Metasomatic changes of this order are very common, and the reactions which can occur are many. With different detritus, different cements, and differ- ent salts in the circulating waters, a vast number of transformations are possible. On this subject it would be difficult to generalize. In a microscopic study of about 150 psammites, as rocks of the sandstone class are sometimes called, G. Klemm 2 identified the fol- lowing substances among their components: Quartz, feldspars, micas, iron ores, zircon, rutile, apatite, tourmaline, garnet, titanite, augite, hornblende, opaline silica, glauconite, carbonates of calcium, magne- sium, and iron, rock fragments, clastic dust, and clay. Even this list is probably far from being exhaustive. An arkose sandstone from the quicksilver region of California, made up of granitic detritus, was found by G. F. Becker 3 to contain quartz, orthoclase, oligoclase, biotite, muscovite, hornblende, titanite, rutile, tourmaline, and apatite. In short, all of the rock-iorming minerals which can in any way survive the destruction of a rock may be found in its sands, and therefore in the sandstones. The feldspars and ferromagnesian min- erals, however, are quite commonly altered or even removed, the more 1 Described by W. S. Bayley in Bull. U. S. Geol. Survey No. 150, 1898, p. 84. Compare C. R. Van Hise, Am. Jour. Sci., 3d ser., vol. 31, 1886, p. 453, for data concerning other similar rocks in the same region. 2 Zeitschr. Deutsch. geol. Gesell., vol. 34, 1882, p. 771. 3 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 59. Several other sandstones are described by J. S. Diller in Bull. U. S. Geol. Survey No. 150, 1898, pp. 72-84. SEDIMENTARY AND DETRITAL ROCKS. 541 stable minerals, like quartz, being much more persistent. Quartz is the most abundant mineral in these rocks, while in rocks of the crystalline and eruptive classes it is subordinate to the feldspars. The following analyses, which, with one exception, were all made in the laboratory of the United States Geological Survey, will suffice to show the general composition of the sandstones : 1 Analyses of sandstones. A. Potsdam sandstone, Ablemans, W isconsin. Analysis by E. A. Schneider. Described by J. S. D iller, Bull. U. S. Geol. Survey No. 150, 1898, p. 80. Nearly pure quartz. B. Brown sandstone, Hummelstown, Pennsylvania. Analysis by Schneider. Described by D iller, op. cit., p. 77. Composed chiefly of quartz, with some feldspar, kaolin, etc. The cement is iron oxide. C. Ferruginous sandstone, “carstone,” from Hunstanton, Norfolk, England. Analysis and description by J. A. Phillips, Quart. Jour. Geol. Soc., vol. 37, 1881, p. 6. Consists of quartz grains cemented by brown iron ore, with very little feldspar and mica. Phillips also gives five other analyses of British sandstones. D. From a “sandstone dike” in Shasta County, California. Analysis by T. M. Chatard. Described by J. S. Diller, Bull. Geol. Soc. America, vol. 1, 1889, p. 411. Made up of quartz, feldspar, and biotite, with a calcite cement. Contains also serpentine, titanite, magnetite, and zircon. Other “sandstone dikes,” near Pikes Peak, Colorado, have been described by W. Cross. They probably represent quicksands which were injected into fissures. See also C. O. Crosby, Bull. Essex Inst., vol. 27, 1895, p. 113. E. Miocene sandstone, Mount Diablo, California. Analyzed and described by W. H. Melville, Bull. Geol. Soc. America, vol. 2, 1890, p. 403. F. Composite analysis of 253 sandstones. By H. N. Stokes. G. Composite analysis of 371 sandstones used for building purposes. By H. N. Stokes. H. Graywacke, Hurley, Wisconsin. Analysis by H. N. Stokes. Described by W. S. Bayley, Bull. U. S. Geol. Survey No. 150, 1898, p. 84. Contains quartz, feldspars, iron oxides, and probably kaolin. In the cement are chlorite, quartz, magnetite, pyrite, rutile, sometimes biotite. and either muscovite, or kaolin. A B C D E F G H Si0 2 99. 42 88. 13 49. 81 48. 13 44. 54 78. 66 84. 86 76. 84 Ti0 2 . . 24 .25 .41 A1 2 0 3 } .31 5. 81 5. 17 11. 19 12. 63 4. 78 5. 96 11. 76 Fe 2 0 3 1. 77 29. 17 1. 25 2. 50 1. 08 1. 39 .55 FeO .31 .35 1. 47 3. 08 .30 .84 2. 88 MnO .29 .44 Trace. Trace. Trace. CaO .20 2. 43 16. 39 14. 65 5. 52 1. 05 .70 SrO [ Trace. None. BaO .04 .05 .01 MgO .53 .95 2. 22 5. 55 1. 17 .52 1. 39 Na 2 0 .06 .84 2. 29 3. 35 .45 .76 2. 57 K 2 0 2. 63 .48 1. 17 1. 37 1. 32 1. 16 1. 62 Li 2 0 ‘ Trace. Trace. H 2 0- } .18 .23 3. 85 .78 1. 43 .31 .27 } 1.87 H 2 0+ .26 6. 56 1. 78 2. 25 fll. 33 al. 47 P 9 0„ .42 . 14 . 29 .08 .06 C0 2 12. 73 7. 76 5. 04 1. 01 so 3 . 07 . 09 Cl Trace. Trace. 99. 91 99. 93 100. 03 100. 11 99. 84 100. 41 99. 86 100. 18 a Includes organic matter. A peculiar rock, which is sometimes called a calcareous sandstone, is the gaize of the French geologists. It has been fully described by 1 For additional analyses, see Bull. U. S. Geol. Survey No. 228, 1904, pp. 291-296. W. Wallace (Proc. Philos. Soc. Glasgow, vol. 14, 1883, p. 22) and W. Mackie ( Trans. Edinburgh Geol. Soc., vol. 8, 1899, pp. 58, 59) give a number of good analyses of Scottish sandstones. See also C. C. Moore, Proc. Liverpool Geol. Soc., vol. 8, 1898, p. 241, for English examples. 542 THE DATA OF GEOC.HEMISTRY. L. Cayeux 1 as a siliceous rock, rich in the debris of siliceous organ- isms, containing quartz and glauconite cemented by opal and clay, with sometimes chalcedony, and very little carbonate of lime. The silica in gaize ranges from 76 to 92 per cent, and a large part of it, 75.3 per cent in the maximum, is soluble in caustic alkalies. It is, as defined by Cayeux, a sedimentary rock, consisting largely of non- clastic silica, and seems to have been originally a marine ooze. FLINT AND CHERT. It is at once evident that a considerable variety of rocks may be formed from siliceous oozes, such as the radiolarian and diatomaceous oozes of the Challenger expedition. These fine sediments may be mixed with more or less clay, spud, or calcareous matter, shading, when consolidated, into shales, sandstones, or siliceous limestones. Their geological relations and their content of amorphous or opaline silica must be depended upon to define them. In the same category we must place infusorial earth, which consists mainly of the siliceous remains of diatoms; and such rocks as flint, chert, and novaculite fall in some cases, if not always, under this general classification. With some exceptions these rocks are commonly of organic origin. The novaculite of Arkansas, however, has been differently interpreted. 2 It is regarded by L. S. Griswold as a siliceous sediment or silt; in other words, as sandstone of extremely fine grain. No organisms could be positively detected in it, nor does it contain an appreciable amount of soluble silica. It is, according to Griswold, essentially a shale minus the argillaceous component, and it forms part of a sedimentary series in which all gradations from shale to novaculite occur. F. Rutley, 3 however, dissents from Griswold’s views, and has sought to show that the novaculite is a siliceous replacement or pseudomorph after limestone or dolomite. It has also been re- garded as a chemical precipitate, analogous to siliceous sinter. In composition the novaculite is very nearly pure silica. The much commoner variety of compact silica known as chert has also been diversely interpreted. A number of writers, 4 studying chert from different localities, have argued in favor of the replacement 1 M4m. Soc. g6ol. du Nord, vol. 4, pt. 2, 1897. Several incomplete analyses of gaize are given. The deter- mination of amorphous silica by its solubility in caustic alkalies, it must be observed, is not very accurate. Silica in any form will dissolve, the rate of solution depending upon the fineness of its subdivision, and the concentration of the alkali. Opaline silica, however, dissolves rapidly in weak alkali, and so can be roughly estimated. Quartz dissolves very slowly. 2 See Griswold’s monograph on this rock (Rept. Arkansas Geol. Survey, vol. 4, 1890) and a paper by the same author in Proc. Boston Soc. Nat. Hist., vol. 26, 1894, p. 414. Compare also O. A. Derby, Jour. Geology, vol. 6, 1898, p. 366; and J. C. Branner, idem,p. 368. Branner sums up very concisely the different theories which have been advanced to account for rocks of this character. * Quart. Jour. Geol. Soc., vol. 50, 1894, p. 380. * E. Hull and E. T. Hardman, Sci. Trans. Roy. Dublin Soc., new ser., vol. 1, 1878, pp. 71, 85, on the Carboniferous cherts of Ireland; A. Renard, Bull. Acad. roy. sci. Belgique, vol. 46, 1878, p. 471, on the phthanites of Belgium; T. Rupert Jones, Proc. Geol. Assoc. London, vol. 4, 1876, p. 439; and others. SEDIMENTARY AND DETRITAL ROCKS. 543 theory. That the replacement of calcium carbonate by silica is possible, no one can deny, for sihcified shells and corals are common. The pseudomorphs of chalcedony or opal after coral, from Tampa Bay, Florida, are conspicuous examples of this change. Furthermore, A. H. Church 1 has effected the transformation artificially. A piece of recent coral was almost completely silicified, losing nearly all its carbonate of lime, when an aqueous solution of silica was allowed to filter through it very gradually. Some chert, then, may have been formed in this way. On the other hand, chert and flint often exhibit evidences of organic derivation. The radiolarian cherts of California, described by A. C. Lawson, C. Palache, and F. L. Bansome , 2 are principally composed of radiolarian remains. Lawson regards these cherts as having been formed by precipitations of colloidal silica from submarine springs, which produced a sort of ooze in which the radiolaria became em- bedded. In other cases cherts were probably derived from sponges, whose spicules consist very largely of opaline silica . 3 Cherts crowded with these spicules have been described by various authors, espe- cially by W. J. Sollas 4 and G. J. Hinde . 5 Hinde studied especially the cherts of the Greensand formation in southern England, the cherts of Spitzbergen, and also the Irish cherts, described by Hull and Hardman. In all of them the sponge spicules were abundant. The same thing is true of the flint nodules found in chalk, which almost invariably show signs of a similar origin . 6 In order to ac- count for these nodules, Sollas suggests that sponge spicules accu- mulated in a calcareous ooze, where, in presence of sea water under pressure, they partly dissolved. The silica thus taken into solution was later reprecipitated around suitable nuclei, at the same time replacing carbonate of lime. It is possible, however, as A. A. Julien 7 has shown, that the organic matter of the decaying sponges may have exerted much influence in bringing about the solution of silica. It is difficult to see how the nodules could have developed except from silica which had been first dissolved. Their growth around organic nuclei can hardly be explained otherwise. Sedimentary rocks consisting almost entirely of silica may orig- inate in divers ways. As siliceous sinter 8 the silica is simply a deposit from hot springs. As sandstone it is an aggregate of finely 1 Jour. Chem. Soc., vol. 15, 1862, p. 107. 2 Lawson, Fifteenth Ann. Kept. U. S. Geol. Survey, 1895, p. 420; Lawson and Palache, Bull. Dept. Geol- ogy Univ. California, vol. 2, 1902, pp. 354, 365; Ransome, idem, vol. 1, 1894, p. 193. a See Thoulet, Bull. Soc. min., vol. 7, 1884, p. 147. * Ann. and Mag. Nat. Hist., 5th ser., vol. 6, 1880, pp. 384, 437; vol. 7, 1881, p. 141. 6 Philos. Trans., vol. 176, 1885, p. 403; Geol. Mag., 1887, p. 435; idem, 1888, p. 241. 6 See Hinde and Sollas, loc. cit., and G. C. Wallich, Quart. Jour. Geol. Soc., vol. 36, 1880, p. 68. J. A. Merrill (Bull. Mus. Comp. Zool., vol. 28, 1895, p. 1) has described fossil sponges from flints found in the Cretaceous near Austin, Texas. '• Proc. Am. Assoc. Adv. Sci., 1879, p. 396. 8 See ante, p. 205. 544 THE DATA OP GEOCHEMISTRY. divided quartz. In gaize and some cherts the rock is composed in great part of organic remains. In some cases calcium carbonate has been obviously replaced by silica. There are also siliceous concre- tion-like flints, as well as the oolites which are formed by the deposi- tion of silica from solution around quartz grains. Such an oolite from Pennsylvania has been studied by several investigators . 1 It is possible that a single formation may represent more than one of these processes. R. D. Irving and C. R. Van Hise , 2 for example, describing the chert of the Penokee iron region, which was laid down simultaneously with the iron carbonates, suggest that it may have been partly derived from organic remains and also be partly a chem- ical sediment. In short, no one process can account for all the occurrences of amorphous or cryptocrystalline silica, and each local- ity must be studied in the light of its own evidence. The following analyses of chert, novaculite, etc., will serve to illustrate the chemical uniformity of these rocks : 3 Analyses of chert and allied rocks. A. Novaculite, Rockport, Arkansas. Analysis by R. N. Brackett. From Griswold’s monograph, p. 167. B. Chert, Belleville, Missouri. Analysis by E. A. Schneider, Bull. U. S. Geol. Survey No. 228, 1904, p. 297. Other analyses are given on the same page. C. Chert from the Upper Carboniferous of Ireland. Analysis by E. T. Hardman, Sci. Trans. Roy. Dub- lin Soc., new ser., vol. 1, 1878, p. 85. Some of the Irish cherts are highly calcareous, representing transitions to siliceous limestone. D. Siliceous oolite, Center County, Pennsylvania. Analysis by Bergt, Abhandl. Gesell. Isis, 1892, p. 115. E. Infusorial earth, Nevada. Analysis by R. W. Woodward, Rept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 768. A B c D E Si0 2 99. 47 98. 17 } .83 95.50 98. 72 } .54 86.70 ALO 1 .17 .10 4.09 Fe 2 0 3 .12 1.95 FeO J .15 1.26 CaO .09 .05 .09 .14 CaC0 3 . . .87 CaS0 4 Trace. MgO .05 .01 Trace. .51 k 2 o .07 } .26 .41 NaaO .15 Trace. .77 PoO- / Trace. ^ 2”5 * Ignition .12 .78 1.43 .34 5.99 100. 24 99.84 100. 00 99. 95 99.87 i E. H. Barbour and J. Torrey, Am. Join-. Sci., 3d ser., vol. 40, 1890, p. 246; E. O. Hovey, Bull. Geol. Soc. America, vol. 5, 1893, p. 627; and Bergt, Abhandl. Gesell. Isis, 1892, p. 115. See also G. R. Wieland, Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 262, who ascribes these oolites to the agency of hot springs. E. S. Moore (Jour. Geology, vol. 20, p. 259, 1912) has also studied these minerals. * Tenth Ann. Rept. U. S. Geol. Survey, pt. 1, 1890, p. 397. See also C. R. Van Hise, A treatise on meta- morphism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 847-853. 3 For other analyses see Griswold’s monograph on novaculite, Hardman’s paper on the Irish cherts, Bar- bour and Torrey on the oolite, and Hovey (Am. Jour. Sci., 3d ser., vol. 48, 1894, p. 401) on cherts from Mis- souri. In a large number of cherts from Kentucky, J. H. Kastle, J. C. W, Frazer, and G. Sullivan (Am. Chem. Jour., vol. 20, 1898, p. 153) found appreciable amounts of phosphates ranging from 0.18 up to 3.5 per cent of P 2 0 5 . SEDIMENTARY AND DETRITAL ROCKS. 545 Other analyses, in considerable number, show intermediate grada- tions between chert and limestone. These represent comminglings in any proportion between the cherty silica and calcium carbonate. That is, silica and calcium carbonate may be deposited together in the same mud or ooze, forming a nearly homogeneous mixture. SHALE AND SLATE. When the finest products of sedimentation consolidate, they tend to form a close-grained, laminated, or fissile rock, which is called shale. As thus used, the term is very vague and has little chemical significance. Sand, reduced to the fineness of flour, may form a rock which is shaly in structure, and so too may limestone. In these cases, however, there is commonly more or less argillaceous impurity in the rocks, so that it is better to call them argillaceous sandstones or limestones. As the term is generally used, a shale is supposed to be a consoli- dated mud or clay in which the aluminous silicates are the more important and characteristic constituents. Shales, therefore, vary in composition exactly as do the materials from which they form, and may contain sandy or calcareous impurities. Bituminous and car- bonaceous shales are also common. Many shales contain pyrite or marcasite, which oxidize and give rise to the formation of sulphates. These rocks are called alum shales and exhibit aluminous efflores- cences. The alum shales and calcareous shales are easily alterable; those which consist chiefly of aluminous silicates, having been formed from the final products of rock decomposition, are remarkably stable. Their disintegration, when it occurs, is largely a mechanical process and involves very little chemical change. Between typical sandstones and typical shales there are pronounced structural differences. A sandstone is made up of grains which are discernible to the eye, and is therefore distinctly porous. In conse- quence of this peculiarity it is easily permeable to percolating waters, the source from which its cementing substances are derived. A shale, on the other hand, consists of much finer particles, which are closely packed, and its porosity is small . 1 In its formation the cementing process is less prominent than in the case of sandstone, and its con- solidation seems to have been effected by a sort of welding. The colloidal matter contained in most muds and clays is capable of binding under the influence of pressure alone; and to unions of this kind a shale mainly owes its coherence. Cementation is not excluded, but it has become a subordinate factor. Under the influence of 1 For data on the fineness of sand and mud particles, see C. R. Van Hise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, p. 892. 97270°— Bull. 616—16 35 546 THE DATA OF GEOCHEMISTRY. pressure, the water of a mud is largely expelled, so that the resulting shale is much less hydrous. The following analyses of shales were all made in the laboratory of the United States Geological Survey. Some constituents, reported in “ traces” only, are omitted from the table. A number of other analyses are given in Bulletin 591, pages 250-258. Analyses of shales. A. Composite analysis of fifty-one Paleozoic stales, by H. N. Stokes. B. Composite analysis of twenty-seven Mesozoic and Cenozoic shales, by H. N. Stokes. C. Black Devonian shale, near Longfellow mine, Horenci district, Arizona. Analyzed by W. F. Hillebrand. D. Middle Cambrian shale, Coosa Valley, Alabama. Analysis by Stokes. E. Bituminous shale, Dry Gap, Georgia. Analysis by L. G. Eakins. F. Shale, near Rush Creek, Pueblo quadrangle, Colorado. Analysis by George Steiger. G. Carboniferous shale, Elliott County, Kentucky. Analysis by T. M. Chatard. H. Cretaceous shale, Mount Diablo, California. Highly calcareous. Analysis by W. H. Melville. Si0 2 . Ti0 2 . A1 2 0. Fe 2 0 FeO. MnO ZnO. 3 CaO BaO MgO.. Na 2 0. . K 2 0. . Li 2 0.. H 2 0- h 2 o+ PA.. co 2 ... so a ... s c Hydrocarbons. Organic matter Pyrite Chalcopyrite. . . A B c D E F G H 60. 15 55. 43 61. 25 55. 02 51. 03 45. 89 41. 32 25. 05 .76 .46 . 66 . 65 .52 .48 16. 45 13. 84 15. 60 21. 02 13. 47 13. 24 20. 71 8. 28 4. 04 4. 00 1. 35 5. 00 8. 06 3. 88 2. 59 .27 2. 90 1.74 3. 04 1.54 5. 46 2.41 Trace. Trace. .07 Trace. . 17 4. 11 . 03 1. 41 5. 96 3. 40 1. 60 .78 12.09 9.91 27. 87 .04 .06 Trace. .04 2. 32 2. 67 4. 16 2. 32 1. 15 2. 12 1.91 1 2.61 1. 01 1. 80 .44 .81 .41 .47 7.19 1 3. 60 2. 67 6. 74 3. 19 3. 16 2. 31 .88 ! Trace. Trace. Trace. .03 .89 2. 11 .62 2.44 1. 38 1.44 3. 82 3.45 2.09 5. 65 } - 81 4. 16 8. 78 2. 86 .15 .20 .08 .06 .31 .17 .08 .08 1. 46 4. 62 .83 10. 38 . 55 24. 20 .58 .78 .02 7. 29 .88 . 69 a 32 13. 11 3. 32 3. 47 .25 .03 100. 46 100. 48 99. 81 100.54 &102. 90 100.08 ( 100. 03 99. 18 ° Carbonaceous matter. & Less 0=S, 100.17. The most noticeable feature in these analyses, as compared with analyses of similar clays, is the change in the iron oxides. In the shales the proportion of ferrous relatively to ferric oxide has increased; probably because of the reducing action of organic matter in the sediments as they were first laid down. Ferric oxide has been evi- dently reduced, and organic substances furnish the most obvious reagents for producing such an alteration. SEDIMENTARY AND DETRITAL ROCKS. 547 Under the long-continued influence of pressure the shales become more compact and less hydrous, and pass into the rocks known as clay slates. By further change, of a metasomatic character, the slates are transformed into the metamorphic mica schists, in which various new minerals appear. The schists will he considered in the next chapter. Even in the slates the effects of metasomatism are manifest, for micas and chlorites appear conspicuously in them. These minerals have been formed at the expense of the clay silicate and the residual feldspars. Scales of detrital mica are, of course, common in the sediments; but in the slates the feldspar grains have been more or less transformed into particles made up of interlocking quartz and mica; the latter usually appearing in the fibrous sericitio form. Even in Carboniferous clays and shales W. M. Hutchins 1 found little kaolin, but more or less secondary quartz, chlorite, and mica. The chlorites, evidently, were derived from the debris of ferromagnesian minerals. The mineralogical composition of the clay slates has been studied by several investigators , 2 and the results are thoroughly summed up by Dale in his memoir upon the slate belt of eastern New York and western Vermont. In these rocks he observed clastic particles of quartz, feldspar, zircon, muscovite, and carbonaceous matter; and autogenous quartz, chlorite, muscovite, pyrite, and carbonates of lime, magnesia, iron, and manganese. Rutile, hematite, and tourma- line were also noted. The pyrite was often altered to limonite. Other observers, studying other slates, have found ottrelite, stauro- lite, garnet, biotite, hornblende, epidote, apatite, pyrrhotite, gypsum, and magnetite in them. The subjoined analyses of roofing slates were all made by W. F. Hillebrand in the laboratory of the United States Geological Survey . 3 1 Geol. Mag., 1894, pp. 36, 64; idem, 1896, pp. 309, 343. 2 See especially W. M. Hutchins, loc. cit.; H. C. Sorby, Quart. Jour. Geol. Soc., vol. 36, Proc., 1880, pp. '66-80; and F. A. Anger, Jahrb. K.-k. geol. Reichsanstalt, Min. Mitt., vol.* 25, 1875, p. 162. T. N. Dale .(Nineteenth Ann. Kept. U. S. Geol. Survey, pt. 3, 1899, pp. 153-307; also Bull. 275, 1906) has made a special study of the roofing slates. His bulletin contains a report by W. F. Hillebrand on the composition of the slates, and closes with a valuable bibliography. 8 See Dale, loc. cit., who cites other analyses. Still others are given in Bull. U. S. Geol. Survey No. 228, 1904, pp. 337-346. J. Roth (Allgemeine undchemische Geologie, vol. 2, p. 588) tabulates 15 analyses of European clays and shales, and H. Rosenbusch(Elemente der Gesteinslehre, 2d ed., p. 442) gives a table of 19. See also E. C. Eckel, Jour. Geology, vol. 12, 1904, p. 25, for the average composition of 36 American roofing slates. 548 THE DATA OF GEOCHEMISTRY. Analyses of roofing slates. A. Sea-green slate, Pawlet, Vermont. B. Purple slate, Castleton, Vermont. C. Black slate, Benson, Vermont. D. Red slate, near Hampton Village, New York. E. Green slate, near Janesville, New York. F. Black slate, Slatington, Pennsylvania. A B c D E F Si0 2 67. 76 60. 96 59. 70 67. 61 56. 49 56. 38 ai 2 0 3 14. 12 16. 15 16. 98 13. 20 11. 59 15. 27 FeA .81 5. 16 .52 5. 36 3. 48 1. 67 FeO 4. 71 2. 54 4. 88 1. 20 1. 42 3. 23 MgO 2. 38 3. 06 3. 23 3. 20 6. 43 2. 84 CaO .63 . 71 1. 27 .11 5. 11 4. 23 Na 2 0 1. 39 1. 50 1. 35 .67 .52 1. 30 K 2 0 3. 52 5. 01 3. 77 4. 45 3. 77 3. 51 h 2 o- .23 .17 .30 .45 .37 .77 h 2 0+ 2. 98 3. 08 3. 82 2. 97 2. 82 4. 09 Ti0 2 .71 .86 .79 .56 .48 .78 C0 2 .40 .68 1. 40 None. 7. 42 3. 67 PA .07 .23 .16 .05 .09 .17 MnO .10 .07 .16 .10 .30 .09 BaO .04 .04 .08 .04 .06 .08 FeS 2 .22 None. 1. 18 .03 .03 1. 72 nh 3 .01 c None. .46 .59 100. 07 100. 23 100. 05 100. 00 100. 38 100. 39 LIMESTONE. The carbonate rocks, which may be either sedimentary, detrital, or metamorphic, are represented principally by limestone and dolomite. Limestone consists of calcium carbonate more or less impure, and it occurs in many forms of very diverse origin. Some limestone, the variety known as calcareous tufa or travertine, is a chemical pre- cipitate, but in its larger masses the rock is generally of organic origin. Chalk is probably derived from a marine ooze; other lime- stones are made up of shells and corals. In some the organic remains are conspicuous; in many cases they are quite obliterated. Sandy, argillaceous, glauconitic, ferruginous, phosphatic, and bituminous limestones owe their names to their manifest impurities. Even gaseous inclusions may give a limestone its name, as in the case of the fetid limestones or “stinkstone” of certain well-known localities. This peculiarity is well shown by a bed of calcite in Chatham Town- ship, Canada, described by B. J. Harrington, 1 which contains 0.016 per cent of hydrogen sulphide. A cubic foot of the rock contains about 500 cubic inches of the inclosed gas, to which its offensive odor, when struck or bruised, is due. The primary source of limestone is obviously to be found in the decomposition of igneous rocks by carbonated waters. Calcium carbonate is thus produced; it passes into solution in ground water, i Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 345. SEDIMENTARY AND DETRITAL ROCKS. 549 springs, and streams, and is thence withdrawn by a variety of proc- esses. Its deposition as a chemical sediment, especially from hot springs, and even from sea water, was considered in a previous chap- ter , 1 but the evidence may well be repeated here and developed a little more fully. Much of the dissolved carbonate is precipitated as a cement in other rocks, but that point needs no further examina- tion now. When waters charged with calcium carbonate are allowed to evap- orate, they deposit their load in the form of sinter, or tufa. This process can be observed at many thermal and “ petrifying” springs, and also in the formation of stalactites and stalagmites in limestone caverns. In this way large masses of compact carbonate may be formed, which are oftentimes of great beauty. The so-called “onyx marbles,” of which the Mexican “onyx” is a familiar example, are formed in this way. Some rock of this class is stalagmitic, from caverns, and some of it is formed by springs . 2 Its variations in color and texture, to which its ornamental character is largely due, are commonly produced by impurities or inclusions, such as oxide of iron, or even mud and clay . 3 WTaen fresh waters, charged with carbonates, enter the sea, a direct precipitation of calcium carbonate may occur. This form of deposi- tion, however, is exceptional, and few authentic examples of it are recorded. It happens only when the supply of carbonate is in excess of that which can be consumed by living organisms and when the conditions of temperature and evaporation are such as to expel the solvent carbon dioxide. By this is meant the carbon dioxide required to hold the carbonate in solution as bicarbonate. These conditions are found, according to Lyell , 4 in the delta of the Rhone, and a similar precipitate has been reported along the coast of Florida . 5 G. H. Drew , 6 however, has shown that bacteria are responsible for a great part of the marine precipitation of calcium carbonate, at least along the coast of Florida, and doubtless elsewhere. This is a different process from that described above. At Pyramid and Winnemucca lakes, in Nevada, great masses of calcareous tufa are formed, and sometimes, according to I. C. Rus- sell , 7 the deposit takes the shape of oolitic sand. In the latter instance the precipitated carbonate is deposited around nuclei, which may be 1 See ante, p. 203. Analyses of tufa and travertine are there given. 2 For a general account of the onyx marbles see G. P. Merrill, Kept. U. S. Nat. Mus., 1893, p. 541. A good table of analyses is given in this memoir. The onyx marbles are usually calcite, rarely aragonite. a On the solubility of calcium carbonate and other carbonates of the series RCO3 in pure and carbonated water, see J. von Essen, Thesis, Univ. Geneva, 1907. 4 Principles of geology, 12th ed., vol. 1, 1875, p. 426. 6 See S. Sanford, Second Ann. Rept. Florida Geol. Survey, 1908-9, pp. 224-5, 228. Also T. W. Vaughan, Pub. 133, Carnegie Inst. Washington, 1910, pp. 114, 168 et seq. 8 Carnegie Inst. Washington, Pub. 182, 1914. See also K. F. Kellerman and N. R. Smith, Jour. Wash- ington Acad. Sci., vol. 4, p . 400, 1914. 7 Mon. U. S. Geol. Survey, vol. 11, 1885, pp. 61, 189. 550 THE DATA OF GEOCHEMISTRY. grains of sand or other foreign bodies. Similar formations occur around Great Salt Lake, but only, as G. K. Gilbert 1 reports, where there is much agitation of the waves. The tufa is not formed in sheltered bays, but where there is surf the overcharge of carbon diox- ide is easily driven out of the water, and calcium carbonate is precipi- tated. Oolitic sand is also found at Great Salt Lake, and in this case its deposition has been traced by A. Rothpletz 2 to the action of minute algae. This mode of formation needs to be considered further. In 1864 Ferdinand Cohn 3 studied the formation of travertine at the waterfalls of Tivoli. He found there that many aquatic plants, especially species of Ohara, mosses, and algae, became incrusted with calcium carbonate — a fact which he attributed to their activity in absorbing carbon dioxide and so setting the carbonate free; that is, plants consume carbon dioxide and exhale oxygen. When they do this in water containing calcium bicarbonate, they deprive that salt of its second molecule of carbonic acid, and the insoluble neutral carbonate is thrown down. The sinter or travertine is thus formed primarily, but it is afterwards transformed into a compact mass by the deposition of calcite in its interstices; and in times of flood, when the waters are muddy, layers of sediment are laid down with it. The same sort of plant activity has been repeatedly observed in connection with the marl deposits of certain fresh-water lakes. The term “marl,” it must be noted, is very vague, and has been applied not, only to earthy forms of calcium carbonate, but also to glauconitic sands containing no carbonate at all. Shell marl, as its name indi- cates, is largely made up of fragmentary shells; the marl here men- tioned is of a different kind. As long ago as 1854 W. Kitchell 4 pointed out that Ohara took an active part in the production of fresh- water marl. In 1900 C. A. Davis 5 6 discussed the subject much more fully, with reference to some lakes in Michigan, and came to essen- tially the same conclusions as Cohn. Davis, however, regards the oxygen liberated by the aquatic plants, Ohara, etc., as assisting in some way the precipitation of the carbonate; but his equation showing the supposed reaction rests on no experimental basis. The activity of plants in marl formation was also considered by W. S. 1 Mon. U. S. Geol. Survey, vol. 1, 1890, p. 167. 2 Am. Geologist, vol. 10, 1892, p. 279. See also E. B. Wethered, Quart. Jour. Geol. Soc., vol. 51, 1895, p. 196, on oolite from other localities. Virlet d’Aoust (Compt. Rend., vol. 45, 1857, p.865), studying the formation of oolite in some Mexican lakes, argues that insect eggs, which are deposited in great numbers on the surface of the water, may act as nuclei. * Neues Jahrb., 1864, p. 580. An earlier paper by Cohn (1862), on the Carlsbad “sprudelstein,” I have not been able to see. It is often quoted. W. H. Weed (Ninth Ann. Kept. U. S. Geol. Survey, 1889, p. 613) has shown that the travertine formed around the hot springs of the Yellowstone National Park is pro- duced by the aid of algae. * First Ann. Rept. Geol. Survey New Jersey, 1855, p. 50. See also G. H. Cook, Geology of New Jersey, 1868, p. 172. 6 Jour. Geology, vol. 8, 1900, pp. 485, 498; vol. 9, 1901, p. 491. SEDIMENTARY AND DETRITAL ROCKS. 551 Blatchley and G. H. Ashley 1 in their report on the lakes of Indiana, but these writers attach fully as much importance to inflowing, lime- bearing springs. The attention which these deposits have received is due to their value for fertilizing purposes. It is possible, as Mr. Bailey Willis has suggested to me, that some marine limestones have been formed by plant agencies. In the shallow seas which are thought to have covered a large part of the North American conti- nent the calcium carbonate may well have been thrown down by algse. To produce a permanent deposit, however, the water must have been too warm to carry much carbonic acid in solution, and too shallow for the precipitate, while sinking, to redissolve. Another process by which calcium carbonate may be precipitated was pointed out by G. Steinmann. 2 He found that albumen, which is present in the organic parts of all aquatic animals, was a distinct precipitating agent. Apparently, by fermentation, the albuminoids generate ammonium carbonate, and to that compound the precipita- tion of calcium carbonate is due. This or any other alkaline car- bonate, entering waters saturated with calcium carbonate, would bring about the separation of the last-named salt. In studying the formation of shell limestone or coral rock, it is desirable to take account of the fact that calcium carbonate exists in at least two geologically important modifications — calcite and aragonite. Calcite crystallizes in the rhombohedral division of the hexagonal system, and has, when pure, a specific gravity between 2.71 and 2.72. Aragonite is orthorhombic, and its specific gravity is near 2.94. Calcite is by far the more abundant form, and it is also the more stable. 3 Aragonite alters easily to paramorphs of calcite, but the reverse change rarely, if ever, occurs. The reported para-, morphs of aragonite after calcite are of doubtful authenticity. Ac- cording to P. N. Laschenko 4 aragonite when heated to 445° begins to change into calcite. The change is complete at 470°. A mono- clinic variety of calcium carbonate, lublinite, has recently been de- scribed by R. Lang. 5 Another crystalline modification since named 1 Twenty-fifth Ann. Rept. Dept. Geology, etc., Indiana, 1900, pp. 31-322. The memoir contains analyses of marls by W. A. Noyes. See also a criticism by C. E. Siebenthal, Jour. Geology, vol. 9, 1901, p. 354. W. C. Kerr, in Geology of North Carolina, vol. 1, p. 187, gives many analyses of marl from that State. An elaborate report on marl, by D. J. Hale, and others, forms part 3 of volume 8, Michigan Geol. Survey, 1900. 2 Ber. Naturforsch. Gesell. Freiburg, vol. 4, 1889, p. 288. 3 See the physicochemical researches of H. W. Foote (Zeitschr. physikal. Chemie, vol. 33, 1900, p. 740), in which this point is developed quantitatively. Important modem papers on the relations between calcite and aragonite are by H. Vater, Zeitschr. Kryst. Min., vol. 21, 1893, p. 433; vol. 22, 1894, p. 209; vol. 24, 1895, pp. 366, 378; vol. 27, 1897, p. 477; and vol. 30, 1899, pp. 295, 485. See also O. Miigge, Neues Jahrb., Beil. Band 14, 1901, p. 246, and H. Leitmeier, Neues Jahrb., 1910, Band 1, p. 49. On the conditions under which calcite and aragonite are formed as chemical precipitates see W. Meigen, Ber. Naturforsch. Gesell. Freiburg, vol. 13, 1903, p. 40, and vol. 15, 1905, p. 38, and H. Warth, Centralbl. Min., Geol. u. Pal., 1902, p. 492. According to W. Vaubel (Jour, prakt. Chem., ser. 2, vol. 86, 1912, p. 366), aragonite contains a small admixture of a hydrobasic carbonate. * Chem. Abstracts, vol. 6, 1912, p. 464. From a Russian original. 5 Neues Jahrb., Beil. Band 38, p. 121, 1914. According to O. Miigge (Centralbl. Min., Geol. u. Pal., 1914, p. 673), lublinite is merely a pseudomorph and not a species. 552 THE DATA OF GEOCHEMISTRY. vaterite, forming spherulitic aggregates, was first observed by H. Vater (loc. cit.), but it is not known to occur in nature. It was pro- duced artificially. In recent years two other varieties of calcium carbonate have been described as distinct from calcite and aragonite. The carbonate of some molluscan shells, which had been called aragonite, was made into a distinct species by Agnes Kelley , 1 who named it conchite. The pisolite formed at the hot springs of Hammam-Meskoutine, Algeria, was given specific rank by A. Lacroix , 2 under the name ktypeite. Both of these alleged species have since been identified with aragon- ite 3 and need no further consideration here. Calcite and aragonite may be distinguished from each other, when not distinctly crystallized, either by their differences in specific gravity or in their optical properties. There are also two chemical tests discovered by W. Meigen . 4 When aragonite is immersed in a dilute solution of cobalt nitrate, it is colored lilac, and the color per- sists on boiling. Calcite, under like treatment, remains white in the cold, but becomes blue on long boiling. Again, calcite, in a solution of ferrous sulphate, produces a yellow precipitate of ferric hydroxide; while aragonite gives a dark-greenish precipitate of ferrous hydrox- ide. These tests were applied by Meigen to a large number of shells and corals, both recent and fossil, and the mineralogical character of each species was determined. A list of the determinations is given in his memoir. The importance of discriminating between calcite and aragonite was pointed out very clearly by H. C. Sorby , 5 in his address upon the origin of limestones. He too, much earlier than Meigen, gave data concerning the calcareous parts of different classes of animals, and showed that shells composed of aragonite rarely appeared as fossils. The same subject was also discussed by V. Cornish and P. F. Kendall 6 on the basis of experiments in which they found that carbonated waters decompose and disintegrate aragonite shells much more readily than shells formed of calcite. The difference, however, 1 Hineralog. Mag., vol. 12, 1900, p. 363. 2 Compt. Rend., vol. 126, 1898, p. 602. For another description of this deposit see L. Duparc, Arch. sci. phys. nat., 3d ser., vol. 20, 1888, p. 537. 3 On conchite, see R. Brauns, Centralbl. Min., Geol. u. Pal., 1901, p. 134. H. Vater (Zeitschr. Kryst. Min., vol. 35, 1902, p. 149), examined both conchite and ktypeite. Vater also describes the Carlsbad “spru- delstein,” which is aragonite. * Centralbl. Min., Geol. u. Pal., 1901, p. 577; Ber. Oberrhein. geol. Verein, 1902, p. 31; Ber. Naturforsch. Gesell. Freiburg, vol. 15, 1905, p. 55. See also A. Hutchinson, Mineralog. Mag., vol. 13, Proc., 1903, p. xxviii; G. Wyroubofl, Bull. Soc. min., vol. 24, 1901, p. 371; and S. Kreutz, Min. pet. Mitt., vol. 28, 1909, p. 487. S. J. Thugutt (Centralbl. Min., Geol. u. Pal., 1910, p. 786) describes color discriminations based upon the use of organic dyes. See also Vaubel (loc. cit.), and K. Niederstadt, Zeitschr. angew. Chemie, vol. 25, 1912, p. 1219. According to G. Panebianco (abstract in Zeitschr. Kryst. Min., vol. 40, 1905, p. 288), the “hydroxides” of Meigen’s reaction are really carbonates. On the ferrous-sulphate test see also W. Diesel, Zeitschr. Kryst. Min., vol. 49, p. 250, 1911. 6 Quart. Jour. Geol. Soc., vol. 35, Proc., 1879, p. 56. 6 Geol. Mag., 1888, p. 66. See also P. Tesch, Proc. Sec. Sci., Amsterdam Acad., vol. 11, 1908, p. 236; A. R. Honvood, Geol. Mag., 1910, p. 173; and G. A. J. Cole and O. H. Little, idem, 1911, p. 49. SEDIMENTARY AND DETRITAL ROCKS. 553 is attributed to structure rather than to mineralogical distinctions. But be that as it may, while calcite organisms remain permanently in fossil form, aragonite shells largely disappear. Only the larger, denser, heavier aragonite structures seem to be preserved to any considerable extent. Kendall 1 has applied these observations to the study of oceanic oozes. The pteropod shells, being mainly aragonite, disappear below 1,500 fathoms depth, while the calcitic globigerina is found in ooze at 2,925 fathoms. From the fact that the Upper Chalk of England contains only calcite organisms, Kendall 2 infers that it was deposited at a depth of at least 1,500 fathoms. Attempts have been made to identify chalk with the globigerina ooze, but L. Cayeux 3 has shown that the two substances are markedly different. Chalk, however, is composed of organic remains, largely foraminif- eral, and undoubtedly represents an ooze of some kind. 4 It also contains detrital impurities, and in chalk from northern France Cayeux 5 has identified microscopic particles of quartz, zircon, tour- maline, rutile, magnetite, muscovite, orthoclase, plagioclase, anatase, brookite, chlorite, staurolite, garnet, apatite, ilmenite, and corundum. These impurities exist in very small proportions, and for practical purposes chalk may be regarded as nearly pure carbonate of lime in exceedingly fine subdivision. In his study of the oolites G. Linck 6 has shown that all recent deposits, so far as he was able to examine them, were composed of aragonite, while the older “fossil” occurrences were calcite — that is, according to his observations, oolite forms as aragonite and slowly changes to the more stable calcite. By experimenting directly with sea water it was found that precipitation with sodium or ammonium carbonate produced aragonite, as determined by Meigen’s reaction with cobalt nitrate. When solutions of calcium bicarbonate alone were allowed to evaporate, Linck further found that at ordinary atmospheric temperature calcite was deposited, but that at 60° arago- nite was formed. In sea water, then, the separation of calcium car- bonate in one modification or the other is conditional upon the proc- ess of precipitation and probably also upon climate. Where organic decay is prominent, the ammonium carbonate produced thereby may act as precipitant, and that is more likely to be the case in warm climates than in cold. The direct deposition of calcium carbonate is commonly in the calcite form, because the temperature of oceanic water is usually low. The two minerals in certain cases may be formed together, and this actually happens in the growth of some 1 Rept. Brit. Assoc. Adv. Sci., 1896, p. 789. 2 Idem, 1896, p. 791. 3 Mem. Soc. g6ol. du Nord, vol. 4, pt. 2, 1897, p. 518. 4 See C. Wyville Thomson, Depths of the sea, London, 1874, pp. 467, 501. 6 Op. cit., p. 257. fi Neues Jahrb., Beil. Band 16, p. 495. Linck gives a good summary of previous literature upon oolite. See also H. Fischer, Monatsh. Deutsch. geol. Gesell., 1910, p. 247. 554 THE DATA OP GEOCHEMISTRY. shells. A shell may consist of a principal mass of calcite, coated by a pearly layer of aragonite, and other associations of the two species in a single animal are well known. In the fossilization of such a shell the aragonite portion is commonly destroyed, while the calcitic layer or fragment is preserved. In what manner do plants and animals withdraw or segregate calcium carbonate from sea water ? To this question there have been many answers proposed, 1 but the problem is essentially physiological, and its full discussion would be inappropriate here. Some of the answers, however, were framed before the modern theory of solutions had been developed, and are therefore no longer relevant. It is not necessary to ask whether the living organisms derive their calcareous portions from the sulphate or chloride of calcium or absorb the car- bonate directly, for these salts are largely ionized in sea water. It is only essential that calcium ions and carbonic ions shall be simul- taneously present; then the materials for coral and shell building are at hand. The carbonic ions may be of atmospheric origin, or brought to the sea by streams, or developed by the physiological processes of marine animals, or a product of organic decay; all of these sources contribute to the one end and help to supply the mate- rial from which limestones are made. Where marine life is abun- dant, there also the carbonic ions abound. This fact is strikingly shown by W. L. Carpenter’s analyses 2 of the gases extracted from sea water and their correlation with the results obtained by dredging. In one series of three samples from different depths, but at the same locality, the gases were composed as follows : Gases extracted from sea water collected at different depths. 862 fathoms (bottom). 800 fathoms. 750 fathoms. o 2 17. 22 17. 79 18. 76 n 2 34. 50 48. 46 49. 32 co 2 48. 28 33. 75 31. 92 100. 00 100. 00 100. 00 On the bottom, where the proportion of C0 2 was highest, animal life was abundant, and the dredge brought up a rich haul. At another point, where the C0 2 at the sea bottom fell to 7.93 per cent, the dredge made a very bad haul. In short, from the composition of the dissolved gases, it was possible to assert whether living forms were scarce or plentiful upon a particular point of the ocean floor. 1 See R. Brauns, Chemische Mineralogie, pp. 377-378, for a summary of this subject. 2 In C. Wyville Thomson’s Depths of the Sea, London, 1874, pp. 502-511. On p. 513 is given a table of analyses of sea water by Frankland, in which the presence of abundant organic matter is shown. SEDIMENTARY AND DETRITAL ROCKS. 555 The most obvious occurrence of limestone building from shells is that which may be observed on many sea beaches. The coquina of Florida is a familiar example of this kind. Masses of shell frag- ments are there compacted together, cemented by calcium carbonate which has been deposited from solution between the bits of shell, and a fairly substantial rock, available for building purposes, is produced. Some quartz sand is commingled with the shell material, and at one locality, noted by W. H. Dali, 1 limonite, deposited by a chalybeate spring, serves as the cementing substance. In the Bay of Naples, according to J. Walther, 2 calcareous algae, especially of the genus Lithothamnium, are conspicuous makers of limestone; and similar observations have been made elsewhere by others. Lithothamnium is a seaweed whose framework or skeleton consists of calcite; another genus, Halimeda, which is also active in limestone making, contains aragonite. 3 From a genetic point of view the coralline limestones have probably been the limestones most carefully studied. Their formation around coral islands and in coral reefs can be observed with the greatest ease, and the process may be followed step by step. First, the living coral; then its dead fragments, broken into sand by the waves; then their cementation by solution and redeposition of calcium car- bonate; and finally the solid rock, made up visibly of organic remains, may be seen. In such limestones, according to E. W. Skeats, 4 both calcite and aragonite occur, directly deposited from the sea water. In composition, when recent, they are like the coral itself, nearly pure carbonate of lime, but a little organic matter is also present, some earthy matter, and very small quantities of calcium phosphate. In corals from the Gulf Stream S. P. Sharpies 5 found from 95.37 to 98.07 per cent of CaC0 3 , and 0.28 to 0.84 of Ca 3 P 2 0 8 . These results are concordant with those obtained by many other analysts, 6 and need no further illustration just now. The alteration of coral rock to dolomite will be considered later. From what has been said in the preceding pages, it is evident that important limestones may be formed in various ways, which, 1 Am. Jour. Sci., 3d ser., vol. 34, p. 163, 1887. 2 Zeitschr. Deutsch. geol. Gesell., vol. 37, p. 329, 1885. a E. J. Garwood (Geol. Mag., 1913, pp. 440, 490, 552) has pointed out the great geologic importance of the calcareous algae. * Bull. Mus. Comp. Zool., vol. 42, pp. 53-126, 1903. b Am. Jour. Sci., 3d ser., vol. 1, 1871, p. 168. 6 See for example, G. Forchhammer, Neues Jahrb., 1852, p. 854, and A. Liversidge, Proc. Roy. Soc. New South Wales, vol. 14, 1880, p. 159, on coral from New Hebrides, and coral rock from Duke of York Island. Also A. J. Jukes-Brown and J. B. Harrison, Quart. Jour. Geol. Soc., vol. 47, 1891, p. 224, on coral rocks from Barbadoes. A number of analyses of coquina, coralline limestones, etc., are given in Bull. U. S. Geol. Survey No. 228, 1904. Several analyses by H. W. Nichols appear in Pub. Ill, Field Columbian Mus., 1906, p. 31. Several analyses of Brazilian corals by L. R. Lenox are in Bull. Mus. Comp. Zool., vol. 44, 1904, p. 264. Others from Florida, the Bahamas, etc., have been recently analyzed in the laboratory of the U. S. Geological Survey. A monographic paper entitled Untersuchungen ueber organische Kalkge- bilde, by O. Biitschli is in Abhandl. K. Gesell. Wiss., Gottingen, new series, vol. 6, No. 3, 1908. This paper is rich in references to literature. 556 THE DATA OF GEOCHEMISTRY. however, are chemically the same. Calcium carbonate, withdrawn from fresh or salt water, is laid down under diverse conditions, yielding masses which resemble one another only in composition. An oceanic ooze may produce a soft, flourlike substance such as chalk, or a mixture of carbonate and sand, or one of carbonate and mud or clay. Calcium carbonate, transported as a silt, may solidify to a very smooth, fine-grained rock, while shells and corals yield a coarse structure, full of angular fragments and visible organic remains. Buried under other sediments, any of these rocks may be still further modified, the fossils becoming more or less obliterated, until in the extreme case of metamorphism a crystalline limestone is formed. All trace of organic origin has then vanished, a change which both heat and pressure have combined to bring about, aided perhaps by the traces of moisture from which few rocks are free. Several experi- mental investigations bear directly upon this class of transformations. To illustrate the influence of pressure alone, we have an important experiment by W. Spring. 1 A quantity of dry, white chalk, inclosed in a steel tube, was placed in a screw press under a pressure of 6,000 to 7,000 atmospheres, and left there for a little over seventeen years. At the end of that time it had become hard and smooth, with a glazed surface, and was somewhat discolored by iron from the tube. It was also in part distinctly crystalline; in short, it resembled to some extent a crystalline limestone, although the change was not absolutely complete. When heated above redness at ordinary pressures, limestone decom- poses into carbon dioxide and lime. This is the common change produced in a limekiln. Under pressure, however, this dissociation is prevented and calcium carbonate may be apparently fused. Over a century ago Sir James Hall 2 heated ' limestone in closed vessels and obtained from it a product identical in general character with crystalline marble. Since Hall’s time the experiment has been repeated by a number of other investigators, under varying condi- tions, with various degrees of success, and with quite dissimilar interpretations. It was supposed at first that Hall had fused lime- stone, and this belief was prevalent for many years. G. Bose, 3 however, transformed a compact limestone into marble as Hall had done, but without evidence of fusion; and A. Becker, 4 in a more extended research, found that by moderate heat and relatively slight pressure calcium carbonate could be converted into a finely granular \ Zeitschr. anorg. Chemie, vol. 11, 1896, p. 160. 2 Trans. Roy. Soc. Edinburgh, vol. 6, 1812, p. 71. The experiments were performed in 1805. For a summary of the results obtained by Bucholz, Petzholdt, and Richthofen, see J. Lemberg, Zeitschr. Deutsch. geol. Gesell., vol. 24, 1872, pp. 237-241. Lemberg criticizes the conclusions drawn from Hall's data, and expresses a strong doubt as to whether fusion actually occurred. 3 Pogg. Annalen, vol. 118, 1863, p. 565. 4 Min. pet. Mitt., vol. 7, 1886, p. 122. Becker also gives a good summary of the earlier literature of the subject. SEDIMENTARY AND DETRITAL ROCKS. 557 mass. A fine powder of the carbonate even developed into larger grains of calcite without either fusing or softening. In the experiments of H. Le Chatelier 1 an actual fusion of the carbonate was perhaps effected. The chemically precipitated car- bonate was inclosed in a steel cylinder between two pistons, under a pressure of about 1,000 kilograms to the square centimeter. Heat was applied by an electric current passing through a spiral of plati- num wire embedded in the mass, and the temperature attained was about 1,050°. Under these conditions the calcium carbonate near the spiral was fused to a translucent mass resembling some marbles. Between the fused and unfused portions there was a sharp demarca- tion, with no indication of any intermediate state. In his second paper Le Chatelier states that even at 1,020° and under slight or insignificant pressure calcium carbonate agglomerates to a crystal- line mass. In similar experiments A. Joannis 2 was able to transform chalk into something like marble at a temperature above the melt- ing point of gold and under a pressure of 15 atmospheres. Joannis suggests that the melting point of calcium carbonate may perhaps be lowered by pressure. H. E. Boeke, 3 however, has obtained a true fusion of calcium carbonate at 1289°, under a pressure of 110 atmospheres. From all of this evidence we may conclude that the change from apparently amorphous calcium carbonate to a distinctly crystalline limestone or marble may be effected by pressure alone, heat alone, or both together. Actual fusion may or may not occur; at all events it seems to be -unnecessary. Furthermore, it is highly probable that water plays some part in bringing about the transformation, for in geological phenomena its influence is rarely excluded. If water did no more than to dissolve and redeposit particles of carbonate, it would go far toward producing the observed change in structure. Under those conditions the carbonate would, in time, become a coarsely crystalline or granular mass of calcite. The following analyses of limestones are all taken from the lab- oratory records of the United States Geological Survey. 4 1 Compt. Rend., vol. 115, 1892, pp. 817, 1009. Two papers. 2 Idem, vol. 115, 1892, pp. 934, 1236. Two papers. 3 Neues Jahrb., 1912, Band 1, p. 91. In another paper, Mitt. Naturforsch. Gesell. Halle, vol. 3, 1913, Boeke has also determined the melting point of barium carbonate, 1,600° under 90 atmospheres pressure, and strontium carbonate, 1,497° under 60 atmospheres. 4 See Bull. No. 228, 1904, pp. 301-336, where 234 analyses of carbonate rocks are given. For other data see T. C. Hopkins, Ann. Rept. Arkansas Geol. Survey, vol. 4, 1890; S. W. McCallie, Bull. Geol. Survey Georgia No. 1, 1904. F. G. Clapp, Bull. U. S. Geol. Survey No. 249, 1905, gives many analyses compiled from the geological reports of Pennsylvania. H. Ries and E. C. Eckel, Bull. New Y ork State Mus. No. 44, 1901; Ries, Fifty-first Ann. Rept. New York State Mus., pt. 2, 1899, pp. 357-467; E. C. Eckel, Bull. U. S. Geol. Survey No. 243, 1905, on cement materials; W. G. Miller, Rept. Bur. Mines (Ontario), pt. 2, 1904; T. C. Hopkins and C. E. Siebenthal, Twenty-first Ann. Rept. Dept. Geology, etc., Indiana, 1896, pp. 293- 427. On the evolution of limestones and the relation of their composition to geologic age R. A. Daly, Bull. Geol. Soc. America, 1909, vol. 20, p. 153. 558 THE DATA OF GEOCHEMISTRY. Analyses of limestones. A. Limestone, Lee, Massachusetts. Analysis by G. Steiger. B. Limestone, Silverdale, Kansas. Analysis by C. Catlett. C. Lithographic stone, Solenhofen, Bavaria. Analysis by Steiger. D. Oolitic sand, Great Salt Lake, Utah. Analysis by T. M. Chatard. E. Coquina, Key West, Florida. Analysis by F. W. Clarke. F. Recent coral ( Siderastrea ), Bermuda. Analysis by L. G. Eakins. G. Composite analysis, by H. N. Stokes, of 345 limestones. H. Composite analysis, by Stokes, of 498 limestones used for building purposes. Does the high pro- portion of silica determine the availability of these rocks to structural ends? Ideally pure calcium carbonate contains 56.04 per cent of CaO and 43.96 of CO 2 . A B c D E F G H Si0 2 0. 95 5. 27 1. 15 a 4. 03 0. 25 0. 23 5. 19 14. 09 Ti0 2 .06 .08 A1 2 0 3 .09 1. 07 1 .45 1 .20 } .56 J jTrace. J . 81 1. 75 FeoO-> None. . 71 1 .54 1 .77 FeO .10 .32 .26 J MnO . 05 .03 CaO 54. 75 50. 36 53. 80 51. 33 51. 52 55. 16 42. 61 40. 60 MrO .56 .56 .56 } .07 .72 2. 08 .20 7. 90 4. 49 K 2 0 . 15 . 10 . 33 .58 Na 2 0 .02 .20 } . 63 .05 . 62 Li 2 0 ) Trace. Trace. H 2 0- } .08 } .78 .23 | .83 } 3. 19 J ) .54 J . 21 .30 H 2 0+ .69 &. 56 &. 88 P 9 0, .03 .06 Trace. .04 .42 C0 2 43. 38 40. 34 42. 69 41. 07 41. 58 43. 74 41. 58 35. 58 s .09 .07 SOo .05 .07 None. .89 .05 .07 Cl. .02 .01 Organic .27 100. 16 99. 84 99. 90 99. 97 99. 18 99. 87 100. 09 100. 34 a Insoluble in hydrochloric acid. & Includes organic matter. Limestones undergo alteration in several ways. They may be silici- fied by percolating waters, or phosphatized, as is often seen on guano islands . 1 By oxidation of inclosed pyrite, acid sulphates can be formed, and these will alter the limestone partially or entirely to gypsum. Acid waters dissolve limestone with evolution of carbon dioxide; and some effervescent springs may owe their sparkling qualities to reactions of this kind. A honeycombed limestone at the bottom of Lake Huron was possibly corroded by water of an acid type. R. Bell 2 found the water of the lake over the limestones to be distinctly acid, the acidity having been possibly derived from sulphides in Huronian rocks to the northward. By thermal metamorphism a lime- stone may be profoundly altered; but that class of changes is to be considered in another chapter. By far the most important alteration 1 On the silicification of limestones see F. Kuhlmann, Ann. Chem. Pharm., vol. 41, 1842, p. 220; J. Lem- berg, Zeitschr. Deutsch. geol. Gesell., vol. 28, 1876, p. 562; and W. Clemm, Inaug. Diss. Freiburg, 1909. On the silicification of fossils, R. S. Bassler, Proc. U. S. Nat. Mus., vol. 35, 1908, p. 133. Onphosphatiza- tion see R. Irvine and W. S. Anderson, Proc. Roy. Soc. Edinburgh, vol. 18, 1891, p. 52; L. Gassner, Inaug. Diss. Freiburg, 1906, and references in the section on phosphate rock in the preceding chapter. 2 Bull, GeoL Soc. America, vol. 6, 1894, p. 30?. SEDIMENTARY AND DETRITAL ROCKS. 559 however, is that produced by waters containing carbon dioxide, especially meteoric waters. These dissolve limestone, and the caverns formed in limestone regions are produced in this way. Great masses of limestone are thus removed, to be deposited, generally in a diffused form, elsewhere. At the same time, the insoluble residual impurities are left behind, in the form of sand, clay, ores of manganese and iron, etc. 1 Some analyses of such residual clays are given in the preceding chapters. These residues are very variable in composition, and rarely approximate to kaolin. This point was developed by H. Le Chate- lier, 2 who dissolved several calcareous marls in acetic acid, and analyzed the residual silicates. Kaolinite was not found in them; but hydrous silicates of aluminum, ill defined and impure, were gen- erally obtained. In one sample from the French Congo, the residue was a silicate of magnesium. According to A. L. Ewing, 3 the rate of limestone erosion in Spring Creek Valley, Center County, Pennsyl- vania, amounts to 275 tons per square mile per annum. 4 This cor- responds to a lowering of the land surface in that region of about one foot in nine thousand years. DOLOMITE. In the foregoing pages upon limestone, the magnesian varieties have been purposely left out of account. They represent transitions from calcium carbonate to dolomite, CaMg(C0 3 ) 2 , a rock of great importance both practically and theoretically, and one which de- mands separate consideration. In addition to dolomite, it is neces- sary also to consider magnesium carbonate itself, magnesite, and its hydrous derivatives, of which several are known. Like calcium car- bonate, these species originate in very different ways, and some of the processes by which they form must be discussed in connection with the subject of serpentine later. Only the compounds of sedi- mentary or organic origin fall within the scope of this chapter. The double carbonate, dolomite, can be produced artificially by several methods, and its accidental formation has also been observed. C. de Marignac 5 obtained it by heating calcium carbonate with a solution of magnesium chloride to 200°, under a pressure of 15 atmos- pheres. J. Durocher 6 heated fragments of porous limestone with dry magnesium chloride to dull redness in a closed gun barrel, in such manner that the carbonate was impregnated by the vapor of the chloride. Under those conditions the limestone was partly changed to dolomite. The local formation of dolomite by volcanic action is 1 See I. C. Russell, Bull. U. S. Geol. Survey No. 52, 1889, for a discussion of this subject. Russell regards the Clinton iron ores of Alabama as residues of this kind, but his views on that matter have been contested. 2 Compt. Rend., vol. 118, 1894, p. 262. 3 Am. Jour. Sci., 3d ser., vol. 29, 1885, p. 29. * Or 29.173 grams per square meter. 6 Cited in a memoir by A. Favre, Compt. Rend., vol. 28, 1849, p. 364. • Idem, vol. 33, 1851, p. 64. 560 THE DATA OF GEOCHEMISTRY. explained by this experiment, but that mode of occurrence is of minor import. C. Sainte-Claire Deville 1 saturated chalk with a solution of magnesium chloride and heated the mass upon a sand bath. A partial replacement of lime by magnesia was thus effected, and similar results were obtained with corals. A. von Morlot, 2 by heating powdered calcite with magnesium sulphate to 200° in a sealed tube, transformed the carbonate into a mixture of dolomite and gyp- sum. This reaction had been suggested by Haidinger, in order to account for the frequent association of the two last-named species. The process, however, is reversible, and solutions of gypsum will transform dolomite into calcium carbonate and magnesium sulphate. Efflorescences of the latter salt are not uncommon in gypsum quar- ries, and H. C. Sorby 3 has observed them in Permian limestones. Because of this reaction, according to Sorby, the upper beds of mag- nesian limestone are often more calcareous than the lower. Their content in magnesia has been diminished in this way. The elaborate experiments of T. Sterry Hunt 4 upon the precipi- tation of calcium and magnesium carbonates, especially by alkaline carbonates from bicarbonate solutions, are too complex to admit of anything like a full summary here. In most of the experiments mixtures of calcium carbonate with the hydrated magnesium com- pound were obtained. When, however, the pasty mass formed by precipitating the two carbonates together was heated to temperatures above 120°, union took place and dolomite was formed. From the fact that a sedimentary dolomite could thus be produced, Hunt con- cluded that dolomite is generally a chemical precipitate, a view which is not widely held to-day. Still more recently G. Linck 5 has reported a synthesis of dolomite effected in the following way: Solutions of magnesium chloride, magnesium sulphate, and ammonium sesquicarbonate were mixed, and to the mixture a solution of calcium chloride was added. An amorphous precipitate formed, which upon prolonged gentle heating in a sealed tube became crystalline, and had the composition and optical properties of dolomite. Linck believes that the conditions of this synthesis are fulfilled in nature, and that ammonium salts derived from organic decomposition play an important part in the formation of marine dolomite. Following Linck, K. Spangenberg 6 succeeded in producing dolomite by heating vaterite with a solution of sodium carbonate and magnesium chloride at 180°-200° in an autoclave under a pressure of 50 atmospheres of carbon dioxide. 1 Compt. Rend., vol. 47, 1858, p. 91. 2 Jahresb. Chemie, 1847-48, p. 1290. Also Compt. Rend., vol. 26, 1848, p. 311. 2 Rept. Brit. Assoc. Adv. Sci., 1856, p. 77. 4 Am. Jour. Sci., 2d ser., vol. 28, 1859, pp. 170, 365; vol. 42, 1866, p. 49. 6 Monatsh. Deutsch. geol. Gesell., 1909, p. 230. W. Meigen (Geol. Rundschau, vol. 1, p. 131, 1900), repeated Linck’s experiment, but without success. 6 Zeitschr. Kryst. Min., vol. 52, p. 529, 1913. SEDIMENTARY AND DETRITAL ROCKS. 561 In several instances the deposition of magnesian travertine and even of crystallized dolomite from natural waters has been observed. According to J. Girardin, 1 the travertine formed by the mineral spring of St. Allyre, near Clermont, in France, is rich in magnesium carbonate. In recent travertine he found 28.80 per cent of MgCO s with 24.40 of CaC0 3 , and in old travertine the proportions were 26.86 and 40.22, respectively. Whether this represents dolomite or a mix- ture of the carbonates was not determined. A. Moitessier 2 found that in a badly closed bottle of water from another French spring distinct crystals of dolomite had been deposited. In another water from a hot spring near the Dead Sea, which was transported to Paris in a sealed tube, similar crystals were found by A. Terreil. 3 From this observation Lartet concludes that the dolomites of the Dead Sea region were probably formed through the impregnation of limestones by magnesian waters. On the other hand, E. von Gorup-Besanez 4 found that springs from the dolomites of the Jura, which contain calcium and mag- nesium carbonates in the dolomite ratio, deposit the mixed salts upon evaporation and not the double compound. Gorup-Besanez observed, however, that carbonated waters, acting upon dolomite, dissolve the mineral with its ratios undisturbed. The occurrence of dolomite geodes in magnesian limestones would seem to show that in such cases at least the double salt can be re-formed. Similar results were earlier obtained by T. Scheerer, 5 when artificial solutions of calcium and magnesium bicarbonate were allowed to evaporate spontaneously at ordinary temperatures. Only mixtures were formed, no dolomite. He also found that powdered chalk precipi- tated magnesium carbonate from a bicarbonate solution, although carbonated waters dissolved calcium carbonate out of magnesian limestones. The last observation, however, had been made by other chemists previously. In Hunt’s investigations it became evident that temperature is an important factor in the formation of dolomite. The same conclusion is to be drawn from F. Hoppe-Seyler’s experiments. 6 At ordinary temperatures a solution of magnesium chloride acting upon calcium carbonate for several months yielded no dolomite. Sea water mixed with an excess of calcium carbonate and saturated with carbon dioxide, after standing four months in a closed flask, 1 Annales des mines, 3d ser., vol. 11, 1837, p. 460. 2 Jahresb. Chemie, I860, p. 178. 3 Cited by L. Lartet, Bull. Soc. g6ol. France, 2d ser., vol. 23, 1866, p. 750. 4 Liebig’s Annalen, Beil. Band 8, 1872, p. 230. 5 Neues Jahrb., 1866, p. 1. 6 Zeitschr. Deutsch. geol. Gesell., vol. 27, 1875, p. 509. In this connection it may be noted that H. C. Sorby (Quart. Jour. Geol. Soc., vol. 35, Proc., 1879, p. 56) found that Iceland spar, in a solution of magnesium chloride, became slowly incrusted with magnesium carbonate. 97270°— Bull. 616—16 36 562 THE DATA OF GEOCHEMISTRY. also failed to form dolomite. But when magnesium salts or sea water were heated with calcium carbonate in sealed tubes, then both dolomite and magnesite were formed. Carbonate of lime, heated to over 100° with a solution of magnesium bicarbonate, gave this result. In the earlier researches upon the conversion of limestone into dolomite little or no attention seems to have been paid to the mineralogical character of the initial substance. In C. Klemenfs experiments 1 aragonite, the less stable form of calcium carbonate and the form which is abundant in coral reefs, was especially studied. It was found that a concentrated solution of magnesium sulphate at 60° would partially transform aragonite into magnesium car- bonate, and coral was altered in the same way. Calcite, by similar treatment, was but slightly attacked. Magnesium sulphate and sodium chloride used together altered aragonite strongly, forming a product containing as high as 41.5 per cent of MgC0 3 . Normal dolomite, ideally pure, would contain 45.7 per cent. Magnesium chloride proved to be less active than the sulphate. The products of these reactions consisted, however, not of dolomite, but of the mixed carbonates, and Klement suggests that mixtures of this kind would probably in time recrystallize into the double salt. He attributes the formation of dolomite to the action of sea water in closed lagoons upon aragonite — that is, upon coral rock. The latter, as will be shown presently, is often the parent of dolomite. It must be observed, however, that aragonite is not the only parent of dolo- mite, for pseudomorphs of dolomite after calcite are well known. 2 Two other investigations upon the synthesis of dolomite remain to be mentioned. L. Bourgeois and H. Traube 3 obtained it by heating a solution of magnesium chloride, calcium chloride, and potassium cyanate, KCNO, to 130° in a sealed tube. This mode of production has no geological significance, except in so far as it shows that the necessary carbonic acid may be supplied from organic or semiorganic sources. Such sources are considered by F. W. Pfaff, 4 who has shown that the products of organic decomposition, as derived from the coral-building organisms, probably take part in the dolomitic process. Not alone carbonic acid is generated during organic decay, but ammonium carbonate, ammonium sulphide, and hydrogen sulphide are also produced, and these compounds, accord- ing to Pfaff, appear to assist in the formation of dolomite. In a 1 Bull. Soc. Beige geol., vol. 9, Mem. 3, 1895. Min. pet. Mitt., vol. 14, 1894, p. 526. See also experiments by O. Mahler, Inaug. Diss., Freiburg, 1906. 2 See Blum’s Pseudomorphosen, p. 51, and Nachtrag, p. 23. 3 Bull. Soc. min., vol. 15, 1892, p. 13. 4 Neues Jahrb., Beil. Band 9, 1894, p. 485. A later paper by Pfaff is published in vol. 23, 1907, p. 529. SEDIMENTARY AND DETRITAL ROCKS. 563 later paper, however, Pfaff 1 states that when a current of carbon dioxide is passed for a long time through a warm solution of the sulphates and chlorides of magnesium and calcium the solution, upon slow evaporation at a temperature of 20° to 25°, yields a residue which contains a double carbonate insoluble in weak hydrochloric acid. That is, under these conditions, which might be approximately paralleled in the concentration of sea water, dolomite may be formed. Under certain exceptional conditions magnesium carbonate may be deposited alone. A solution of the bicarbonate on evaporating spontaneously forms the hydrous salt MgC0 3 .3H 2 0, which corre- sponds to the rare mineral nesquehonite. This species, described by F. A. Genth and S. L. Penfield, 2 from the Nesquehoning anthracite mine in Pennsylvania, was there produced by the alteration of a basic carbonate, lansfordite, 3 3MgC0 3 .Mg(0H) 2 .2lH 2 0, which first formed as stalactites in one of the galleries. Nesquehonite has since been identified by C. Friedel 4 as a similar formation in a French coal mine. Such stalactiform minerals are obviously deposited from solution in carbonated waters. The term “ dolomite” is sometimes loosely used by geologists as equivalent to magnesian limestone. Any limestone containing nota- ble amounts of magnesia may be described by this name. Properly, the word should be restricted to the definite double carbonate, which occurs both as a well-crystallized mineral and as a massive rock. When, after allowing for natural impurities, the molecular ratio of lime to magnesia in such a rock is 1:1, it is legitimately, at least in most cases, a dolomite, but exceptional mixtures are, of course, possible. Ordinarily, a magnesian limestone is a mixture of dolo- mite and calcite, with such impurities as sedimentary rocks and lime- stones in general are likely to contain. In these rocks the ratio of lime to magnesia is greater than 1:1; but in computation it must be remembered that some dolomites contain iron, which replaces magnesia in equivalent amounts. Ferruginous dolomite, or ankerite, is not rare. All the iron of a carbonate rock, however, is not neces- sarily a part of the carbonate. It may be present as hydroxide or in claylike impurities, and these possibilities must be taken into account in any interpretation of the dolomites. In some cases free 1 Centralbl. Min., Geol. u. Pal., 1903, p. 659. Pfaff regards pressure as an important factor in the forma- tion of dolomite. His conclusions are criticized in an important paper by E. Philippi (Neues Jahrb. Festband, 1907, p. 397), who cites evidence to show that certain dolomitic nodules have been formed by chemical precipitation. F. Tucan (Centralbl. Min., Geol. u. Pal., 1909, p. 506) finds that the Karst dolo- mites of Croatia contain sodium chloride and calcium sulphate, which suggests a marine origin. E. Steidtmann(Jour. Geology, vol. 19, 1911) has also studied the marine relationships of dolomite. 2 Am. Jour. Sci., 3d ser., vol. 39, 1890, p. 121. 3 Described by Genth, Zeitschr. Kryst. Min., vol. 14, 1888, p. 255. 4 Bull. Soc. min., vol. 14, 1891, p. 60. See also H. Leitmeier (Zeitschr. Kryst. Min., vol. 47, 1909, p. 118) on the deposition of magnesian hydrocarbonates by the mineral springs of Rohitsch, Styria. 564 THE DATA OF GEOCHEMISTRY. magnesian carbonates must also be considered, and in certain alter- ation products, brucite, Mg0 2 H 2 , may also occur. Commonly the dolomites are fairly simple in composition, and difficulties in inter- preting the analyses rarely arise. In the study ‘of natural dolomites as well as in the synthetic ex- periments which have just been described, it is often necessary to discriminate between the separate carbonates and the true double salt. In most cases this is easily done by taking advantage of differ- ences in solubility. Calcite and aragonite dissolve easily in weak acetic or hydrochloric acid; dolomite and magnesite, at ordinary temperatures, are attacked slowly. 1 These magnesian carbonates are not absolutely insoluble in dilute acids, but they are sufficiently resistant to admit of a rough separation from calcite, and their subse- quent identification. From a mixture of dolomite and calcite, cold dilute acetic acid will dissolve the latter mineral, leaving nearly all of the dolomite unattacked. From mixtures of calcite and magne- site, on the other hand, all of the lime will be thus removed. Some magnesia also may pass into solution, for as Vesterberg has shown, there are magnesian carbonates, probably basic or hydrous, which dissolve with ease. Magnesite is even more refractory toward sol- vents than dolomite. Furthermore, discrimination between calcite and dolomite can be effected by microchemical tests. Among the best of these is that described by J. Lemberg, 2 whose reagent consists of a solution of aluminum chloride and hsematoxylin (extract of logwood). This reagent deposits a violet coating upon calcite surfaces, but leaves dolomite uncolored. According to F. Cornu, 3 the two minerals are easily distinguished by covering the powdered material with water and adding a few drops of phenolphthalein solution. Calcite gives a strong coloration; dolomite is affected but slightly. E. Hinden 4 states that limestone is colored red-brown by ferric chloride solution, and blue by copper sulphate, dolomite remaining unchanged. So far as the experimental evidence goes, dolomite can be formed in several ways. In specific cases, however, field evidence must be brought to bear. First, dolomite may exist as a true chemical sedi- ment, although occurrences of this kind are probably rare. G. Leube 5 6 1 Upon these differences in solubility there is an abundant literature, which has been well summarized by A. Vesterberg, Bull. Geol. Inst. Upsala, vol. 5, 1901, p. 97; vol. 6, 1905, p. 254. See also the synthetic papers already cited, and Haushofer, Sitzungsb. K. Akad. Wiss. Miinchen, vol. 11, 1881, p. 220. 2 Zeitschr. Deutsch. geol. Gesell., vol. 40, 1888, p. 357. In vol. 39, 1887, p.. 489, Lemberg describes tests based upon the use of ferric chloride and ammonium sulphide. In a still earlier paper (op. cit., vol. 24, 1872, p. 226) Lemberg gives tests with silver nitrate, which stains calcite and dolomite, after ignition, unequally. See also Otto Meyer, Zeitschr. Deutsch. geol. Gesell., vol. 31, 1879, p. 445. 3 Centralbl. Min., Geol. u. Pal., 1906, p. 550. * Verhandl. Naturforsch. Gesell. Basel, vol. 15, 1903, p. 201. O. Mahler (Inaug. Diss., Freiburg, 1906) finds the ferric chloride unsatisfactory but obtained good results with the copper salt. On the copper test see also K. Spangenberg, Zeitschr. Kryst. Min., vol. 52, p. 529, 1913. 6 Neues Jahrb., 1840, p. 371. SEDIMENTARY AND DETRITAL ROCKS. 565 described a “ fresh-water dolomite” near Ulm, in Bavaria; and C. W. Giimbel, 1 studying the dolomites of the same region, which are interbedded with limestones, likewise asserts their sedimentary ori- gin. T. Scheerer 2 also argues that the oldest dolomites were formed as chemical precipitates; and T. Sterry Hunt’s 3 positive views on this subject are well known. Hunt’s experiments help us to under- stand how sediments of dolomite may perhaps be formed; and it is also possible that algae may precipitate mixed carbonates just as they do calcareous marl. When the carbonates are thrown down together, heat and pressure may combine to bring about their union. These suggestions relate to possibilities only; and it would be rash to assert positively that dolomites are ever formed on a large scale by direct sedimentation. Magnesian carbonates are, however, deposited with calcium carbon- ate by marine organisms, albeit in small relative amounts. G. Forch- hammer 4 made many analyses of shells and corals, finding mag- nesium carbonate in them in percentages ranging from 0.15 to 7.64, 1 per cent being rather above the average. This result has been con- firmed by many other investigators. In Lithothamnium nodosum Giimbel 5 found 2.66 per cent of MgO and 47.14 of CaO; and A. G. Hog- bom 6 in fourteen analyses of algse belonging to this genus reports from 1.95 to 13.19per cent of MgC0 3 . To these higher figures refer- ence will be made later. In 1906 H. W. Nichols 7 published an analysis of the skeleton of a recent crinoid, and found in it about 11 per cent of magnesium carbonate. Several years later C. Palmer, in the laboratory of the U. S. Geological Survey, analyzed two more crinoids, and obtained similar results. In 1914 the subject was taken up more extensively by F. W. Clarke and W. C. Wheeler, 8 and 24 analyses were made, representing 21 genera of crinoids and a wide range of habitat. In all of them magnesium carbonate was found, in proportions ranging from 7.28 to 12.69 per cent, the amount varying with the temperature of the water in which the creatures lived. In cold-water forms the figure for magnesia was low, while in tropical forms the figure was high; a sharply defined relation for which an explanation is yet to be found. This research was followed up by a series of analyses of the 1 Sitzungsb. K. Akad. Wiss. Miinchen, 1871, Heft 1, p. 45. 2 Neues Jahrb., 1866, p. 1. 3 See Chemical and geological essays, p. 80, and the literature already cited. * Neues Jahrb., 1852, p. 854. The highest figure in Forchhammer’s series was for an annelid, Serpula. ^ Abhandl. K. Akad. Wiss. Miinchen, vol. 11, 1871, p. 26. 6 Neues Jahrb., 1894, Band 1, p. 262. The analyses were made by a number of chemists for Hog- bom, who gives data for several shells and corals also. In the latter organisms the magnesia was low. R. C. Wallace (Jour. Geology, vol. 21, p. 416, 1913) has considered the relation of calcareous algse to the production of dolomite. 7 Field Columbian Museum, Pub. Ill, p. 31, 1906. See also A. H. Clark, Proc. U. S. Nat. Mus., vol. 39, p. 487, 1911. 8 Prof. Paper U. S. Geol. Survey No. 90-D, 1914. 566 THE DATA OP GEOCHEMISTRY. inorganic parts of sea urchins, starfishes, and brittle stars, with results strictly comparable with and parallel to those found for the crinoids. 1 Similar quantities of magnesia were found, and the same temperature regularity was observed. In short it seems to be established that the inorganic constituents of any echinoderm will have the composition of a moderately magnesian limestone, and the largest proportion of magnesia will be found in organisms from relatively warm waters. 2 It is not to be assumed, however, that magnesian sediments follow the same rule. A dense population of forms low in magnesia would deposit a larger amount of it than a sparse population of richer organisms. Clarke and Wheeler also report analyses of 10 fossil crinoids, ranging from the Ordovician up to the Eocene, but with inconclusive results. Alterations due to leaching and to infiltration of foreign substances such as silica and the carbonates of iron and manganese effectually obliterated all the regularities shown by the recent living forms. The calcareous algae analyzed by Hogbom show no such temperature relations as are exhibited by echinoderms. From these data it is clear that limestones formed by marine organisms must contain magnesia, and evidence shows that as a rule they contain rather more of it proportionally than the remains from which they are made. The analyses of oceanic oozes collected by the Challenger expedition, as discussed by Hogbom, 3 show this fact very well, and also illustrate the tendency of the magnesium carbonate to accumulate, while the more soluble calcium carbonate is dissolved away. That is, by the leaching of these deposits they become rela- tively enriched in magnesia, until in the extreme cases something very near the true dolomite ratio is attained. In short, a dolomite may be produced by concentration from a magnesian limestone, and either sea water or percolating waters of atmospheric origin may operate in this way. Grand jean 4 was probably the first to interpret certain dolomites as having been formed by this process, a view which various other writers have adopted and which is well developed in Hogbom’s memoir. Hogbom, in addition to the facts already cited, brings other important evidence to bear upon the problem. He shows that stalactites from caverns in the coral rocks of Bermuda contain only 0.18 to 0.68 per cent of magnesium carbonate, while the rocks themselves carry about five times as much. 5 Here the lime 1 Prof. Paper U. S. Geol. Survey No. 90-L, 1915. A similar temperature relation has. been found by Clarke and Wheeler in a series of analyses of alcyonarians not yet published. 2 A few other analyses of echinoderms, namely, sea urchins and starfishes, are on record. See L. Schmelck, Norske Nordhavs-Expedition, No. XXVIII, p. 129, 1901; and O. Biitschli, Abhandl. K. Gesell. Wiss. Gottingen, new ser., vol. 6, No.3,pp. 81-83, 1904. In a holothurian, Stichopus regalis, 8.37 per cent of magnesium carbonate was found. Another holothurian analyzed by A. Hilger (Arch, gesammte Physio- logic, vol. 10, p. 214, 1875) contained 12.10 per cent, calculated on the calcined ash of the creature. Locali- ties and temperatures were not given with these analyses. 3 Op. cit., p. 267. * Neues Jahrb., 1844, p. 543. 6 It is well known that stalactites from caverns in dolomitic limestones consist essentially of calcium carbonate, with little or no magnesia. Sedimentary and detrital rocks. 567 salt has dissolved much more freely than the magnesium compound. Hogbom also studied the marine marls of Sweden, and found that the transported material contained progressively larger proportions of magnesium carbonate as its distance from the parent limestone increased. Near its point of origin the marl carried 3.7 parts of MgC0 3 to 100 of CaC0 3 ; and from these figures the ratio was gradually raised to 36 MgC0 3 and 100 CaC0 3 . In these finely divided sediments the leaching out of calcium carbonate by atmos- pheric and glacial waters is naturally rapid, and the concentration of the dolomitic portion is effected with great ease. This mode of concentration, then, must be recognized as real, and as accounting in part at least for the formation of dolomite; 1 but it is not the whole story. It accounts for some occurrences but not all. Coral rock, it will be remembered, consists chiefly of calcium car- bonate, which in the living forms is mineralogically aragonite; but in 1843 J. D. Dana, 2 in a rock from the coral island of Makatea, in the Pacific, reported magnesium carbonate to the extent of 38.07 per cent. This approached the dolomite ratio, which requires 45.7 per cent, and the thought was at once suggested that the rock had been dolomitized by the introduction of magnesia from sea water, the latter having possibly been first concentrated by evaporation in a shallow lagoon. Since Dana’s observation was made, many other investigators have recorded similar enrichments of coral reefs, and the synthetic experiments of various chemists, as cited in the preceding pages, have shown that the indicated reaction can actually take place. Element ’s experiments, especially, have helped to make this point clear. In a coral reef from Porta do Mangue, Brazil, J. C. Branner 3 reports 6.95 per cent of magnesia, equivalent to 14.5 of carbonate, while the corals themselves contained only 0.20 to 0.99 per cent of MgO. In the islands of the Pacific Ocean a large number of similar cases have been observed, the analyses by E. W. Skeats 4 rising to a maximum of 43.3 per cent of MgCO a . From instances of this kind, and from the resemblance of many dolomites to reef rocks, it has been com- monly inferred that dolomitization is generally, or at least often, effected in this way, lime being gradually removed and replaced by magnesia from the sea. 5 6 1 For an elaborate discussion of this side of the dolomite problem see G. Bischof, Lehrbuchder chemischen und physikalischen Geologie, 2d ed., pp. 52-91. The older data are wellsummarized. See also C. W. Hall and F. W. Sardeson, Bull. Geol. Soc. America, vol. 6, 1894, p. 189. 2 See Dana’s Coral and coral islands, 3d ed., p. 393. Analyses by B. Silliman, jr. The island is called Metia by Dana. 8 Bull. Mus. Comp. Zool., vol. 44, 1904, p. 264. Analysis of rock by R. E. Swain, of the corals by L. R. Lenox. * Idem, vol. 42, 1903, pp. 53-126. 6 See R. Harkness, Quart. Jour. Geol. Soc., vol. 15, 1859, p. 103, on dolomite near Cork, Ireland. Also C. Doelter and R. Hoemes, Jahrb. K.-k. geol. Reichsanstalt, vol. 25, p. 293. These authors give a bibliog- raphy of dolomitization, down to 1875, the date of their memoir. 568 THE DATA OF GEOCHEMISTRY. The most striking illustration of this mode of transformation is furnished by the borings on the atoll of Funafuti, as discussed by J. W. Judd. 1 The principal boring was driven to a depth of over 1,100 feet through coral and coral rock all the way, and samples of the cores were analyzed for practically every 10 feet of the dis- tance. From the table of data presented by Judd, the following figures are selected: Magnesium carbonate in borings on atoll of Funafuti. Depth, feet. Percentage MgCO s . Depth, feet. Percentage MgC0 3 . 4 4. 23 295 3.6 13 7. 62 400 3.1 15 16.4 500 2.7 20 11. 99 598 1. 06 26 16.0 640 26. 33 55 5. 85 698 40. 04 110 2. 11 795 38. 92 159 .79 898 39. 99 200 2. 7 1,000 40. 56 250 4.9 1,114 41. 05 These figures are very remarkable. They show, first, an enrich- ment in magnesium carbonate near the surface, then an irregular rising and falling in much smaller amounts, while below 700 feet the approach to a dolomite ratio is apparent. The surface enrichment Judd attributes to a possible leaching out of lime salts, and the irregularities may be due in part to differences in the proportions of the various reef-forming organisms. Some of these are more soluble than others, as we have already seen. Algae, especially Lithothamnium and Halimeda , are abundant at Funafuti, and Judd suggests that the abnormally high magnesia found by Hogbom in these organisms may also be due to leaching, possibly aided by carbon dioxide derived from the decomposition of the plants after death. The replacement of lime by magnesia extracted from sea water probably takes place at the same time, so that two distinct processes combine to produce the final result. It is noticeable that the lower portions of the core, which were the earliest deposited and have therefore been acted upon for the longest time, are the most completely changed. In this double process of leaching and replacement, we find the nearest approach to a satisfactory theory of dolomitization in coral reefs. It is, however, not general, as the following analyses by 1 The atoll of Funafuti, published by the Royal Society, London, 1904. For Judd’s report on the chem- ical examination, see pp. 362-389. SEDIMENTARY AND DETRITAL ROCKS. 569 George Steiger, 1 of borings from an artesian well at Key West, Florida, clearly show: Lime and magnesia in borings at Key West. Depth, feet. Percentage CaO. Percentage MgO. Depth, feet. Percentage CaO. Percentage MgO. 25 54. 03 0. 29 1,325 54. 49 0. 62 100 54. 01 .77 1,400 55. 12 .30 150 54. 38 .86 1,475 54. 48 .73 350 51. 46 1. 67 1,625 53. 90 1. 14 600 48. 87 2. 50 1,850 54. 28 1. 12 775 46. 53 6. 70 2, 000 54. 02 1. 06 1,125 53. 84 .86 Here there is a progressive magnesian enrichment down to 775 feet, and then a falling off, but no such thorough alteration appears as at Funafuti. What different conditions may have existed to account for these differences of composition is not known. It is of course evident that dolomitization by replacement need not be limited to the action of sea water upon coral reefs. Magnesian spring waters may be equally effective, and are so locally, as observed by J. E. Spurr 2 in the rocks about Aspen, Colorado. In that region hot springs containing magnesium are manifestly operative in trans- forming limestone to dolomite. But large areas of dolomite are not likely to originate in that way. Where, however, limestones are situated near magnesian eruptive rocks, dolomitization due to this cause is to be anticipated. The following analyses of magnesian limestones were made in the laboratory of the United States Geological Survey. 3 Other analyses in abundance are scattered through the literature of limestones. 1 Analyses made in the laboratory of the United States Geological Survey. Published in full in Bull. No. 228, 1904, p. 309. Boring described by E. O. Hovey, Bull. Mus. Comp. Zool., vol. 28, 1896, p. 63. 2 Mon. U. S. Geol. Survey, vol. 31, 1898, p. 206. Spurr (p. 216) also reports an interesting silicification of limestones, which is visible in all its stages. The final product is made up of quartz grains. The mag- nesian enrichment of slates at the expense of sea water has been described by J. A. Phillips, Quart. Jour. Geol. Soc., vol. 31, 1875, p. 324. A recent paper by M. Nahnsen on the formation of oolite and dolomite is in Neues Jahrb., Beil. Band 35, 1913, p. 277. A study of the mixed carbonates of lime, magnesia, and iron, by K. Griinsberg, is in Zeitschr. anorg. Chemie, vol. 80, 1913, p. 337. For an attempt to apply the principles of physical chemistry to dolomitization, see R.. C. Wallace, Compt. rend. XII Cong. geol. internat., 1913, p. 875. 3 See Bull. No. 591, 1915, pp. 225-249, for these analyses and others. 570 THE DATA OF GEOCHEMISTRY. Analyses of magnesian limestones. A. Green Peak Quarry, Dorset, Vermont. Analysis by George Steiger. Described by T. N. Dale in Bull. No. 195, 1902. B. “Knox dolomite,” Morrisville, Alabama. Analysis by W. F. Hillebrand. Described by I. C. Rus- sell in Bull. No. 52, 1889. C. Penokee district, Wisconsin. Analysis by Hillebrand. See R. D. Irving and C. R. Van Hise, in Mon., vol. 19, 1892. D. “Niobrara dolomite,” Denver Basin, Colorado. Analysis by L. G. Eakins. Described by Emmons in Mon., vol. 27, 1896. E. Near Red Mountain, Silver Peak district, Nevada. Analysis by Steiger. F. The theoretical composition of ideally pure dolomite. A B c D E F Insoluble 12.01 0. 31 Si0 2 8.36 3.24 0. 63 A1,0, 1. 77 .17 .54 Fe 2 0 3 .22 .17 .03 .11 FeO 1.08 .06 .75 1.89 MnO .08 .20 MgO 16.68 20.84 20.68 18.03 20. 19 21.9 CaO 29.03 29.58 30. 94 27.49 30. 35 30.4 Na.,0 .06 K 2 0 1.08 HoO- .03 } .30 } .27 } .61 H 2 0-f .42 C0 2 41.66 J 45.54 46.27 41.40 47.21 47.7 PoO, .03 Cl Trace. 100. 39 99.90 99.65 100. 42 99.95 100.0 Under ordinary atmospheric and aqueous conditions dolomite alters like limestone, but less readily. By volcanic agencies, that is, the combined action of heated or fused rooks and steam, dolomite is sometimes transformed into a substance which was once thought to be a distinct mineral species, and was named predazzite and penca- tite by different investigators. This substance has been interpreted by Damour, 1 G. Hauensohild, 2 J. Roth, 3 and J. Lemberg 4 as a mix- ture of oalcite and brucite, Mg0 2 H 2 . O. Lene6ek, 5 however, regards it as a mixture of calcite and hydromagnesite, the latter being partly pseudomorphous after periclase and partly an infiltration. In either case the dolomite has been altered by the transformation of its mag- nesium carbonate into a basic salt or into hydroxide. The latter compound, under some conditions, can be leached away, leaving nearly pure calcite; or it may be dehydrated, forming periclase, MgO. Predazzite was first observed at Predazzo, in the Tyrol; and 1 Bull. Soc. gdol. France, 2d ser., vol. 4, 1847, p. 1050. 2 Sitzungsb. K. Akad. Wiss. Wien, vol. 60, 1870, p. 795. 3 See Allgemeine und chemische Geologie, vol. 1, pp. 422-425. Roth cites many analyses of altered dolomites and gives the data concerning predazzite with considerable fullness. 4 Zeitschr. Deutsch. geol. Gesell., vol. 24, 1874, p. 187. 6 Min. pet. Mitt., vol. 12, 1892, pp. 429, 447. Lenedek gives a good summary of the literature of predazzite. SEDIMENTARY AND DETRITAL ROCKS. 5n Lemberg, by acting on normal dolomite from that locality with steam, obtained a similar product. A like alteration of dolomite from a Russian locality was also reported by F. Rosen. 1 IRON CARBONATE. Another important rock-building carbonate is siderite, the ferrous carbonate FeC0 3 . Its formation as bog ore has already been con- sidered, 2 together with its transformation into limonite, but its rela- tions to limestone and dolomite remain to be noticed. Between these rocks there are many transitional mixtures, and ankerite, the ferrif- erous dolomite, is one of them. This mineral contains iron replacing magnesium, to use the ordinary phraseology, but this implies that the double salt CaFeC 2 0 6 exists isomorphous with and equivalent to the magnesian compound, dolomite. The two salts, CaFeC 2 0 6 and CaMgC 2 0 6 , may commingle in any proportion, and varieties contain- ing manganese carbonate are also known. So, too, there are mixtures of magnesite and siderite, known as breunnerite, mesitite, and pis- tomesite, but they are comparatively unimportant except in the study of isomorphism. The manganese carbonate, rhodochrosite, MnC0 3 , is usually a mineral of metalliferous veins. As bog ore, siderite is deposited from a bicarbonate solution in presence of organic matter and out of contact with air. But siderite, like dolomite, may also be formed by replacement when iron solu- tions act upon limestones. H. C. Sorby 3 found that Iceland spar immersed in a solution of ferrous chloride was slowly transformed into crystalline siderite; in ferric chloride, on the other hand, ferric hydroxide was formed. A similar precipitation of limonite was observed by G. Keller 4 when oalcite was treated with ferric sulphate. Reactions of this kind have often been invoked in the interpretation of sedimentary iron ores. J. P. Kimball, 5 for example, regards the reaction of ferrous solutions upon limestones as of the highest impor- tance, and refers to isolated masses of coral reef in Cuba which have been so replaced by iron compounds. Fossils, originally calcareous, but now composed of limonite, are not rare. In the Jurassic lime- stones of central France ores of iron, manganese, and zinc are widely disseminated. According to L. Dieulafait, 6 these ores were precipitated from solution by calcium carbonate, the iron first, zinc and manganese later. The iron ores are always at the bottom of the series, and the other metals are found in the overlying limestones. 1 Arch. Naturkunde Liv., Esth. u. Kurlands, 1st ser., vol. 3, 1864, p. 142. 2 See ante, p. 530. * Quart. Jour. Geol. Soc., vol. 35, Proc., 1879, p. 73. 4 Neues Jahrb., 1882, Band 1, ref., p. 363. <> Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 231. 6 Compt. Rend., vol. 100, 1885, p. 662. 572 THE DATA OF GEOCHEMISTRY. Like carbonate of lime, iron carbonate may be removed from solu- tion by aquatic vegetation. The process, however, is different in one particular. Ferrous carbonate is easily oxidized to limonite, and that change, which takes place in air alone, is doubtless accelerated by the oxygen which the plants exhale. The deposit formed is not siderite then, but hydroxide. Similar precipitation of limonite may also occur from sulphate solutions, as in or near a chalybeate spring in Death Gulch, Yellowstone National Park. Here, according to W. H. Weed, 1 the mosses form, from the water of the spring, an iron sinter, which was analyzed by J. E. Whitfield in the laboratory of the United States Geological Survey with the following results : Analysis of iron sinter. Si0 2 1. 37 Fe 2 0 3 63.03 A1 2 0 3 08 S0 3 8.35 H 2 0 and organic matter 26. 94 99. 77 The instability of ferrous carbonate is also shown by the deposits of iron rust around iron-bearing springs in general, and by the forma- tion of stalactites of limonite. Such stalactites were formed exactly like calcite stalactites, by carbonate solutions, only the iron salt has decomposed and left residues of hydroxide. According to T. Sterry Hunt 2 the alteratioi\ of siderite to limonite is attended by a contrac- tion of 27.5 per cent, whence limonite ore bodies are often porous or spongy. The vast deposits of iron ores in the Lake Superior region, limo- nites, hematites, magnetites, etc., are now regarded as in great measure secondary bodies derived from iron carbonates of sedimen- tary origin. The process by which their concentration was probably effected has been summed up by C. E. Van Hise 3 as follows: First, meteoric waters attacked the upper portions of the original carbon- ate, oxidizing the latter to limonite. In so doing the waters lost their dissolved oxygen and became carbonated. In this condition the waters dissolve ferrous carbonate, with some silicate, and transfer it to lower levels. Later, the surface oxidation having been com- pleted, waters charged with atmospheric oxygen percolate downward, mingle with the iron solutions previously formed, and precipitate 1 Am. Geologist, vol. 7, 1891, p. 48. 2 Canadian Naturalist, vol. 9, 1881, p. 431. 3 Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 3, 1900, p. 326. Monographs 19, 28, 36, 43, 45, and 46 of the Survey, by Irving, Van Hise, Clements, Smyth, Bayley, and Leith, deal exhaustively with these “Lake Superior” ores. See also J. E. Spurr, Bull. No. 10, Geol. Nat. Hist. Survey Minnesota, 1894, on the Mesabi ores; and S. Weidman, Bull. No. 13, Wisconsin Geol. Nat. Hist. Survey, 1904, on the Baraboo district. Bull. No. 6 of the Minnesota Survey, 1891, by N. H. and H. V. Winchell, is devoted to a dis- cussion of the Minnesota deposits. SEDIMENTARY AND DETRITAL ROCKS. 573 limonite. The latter* by heat and pressure* may be transformed to hematite. A similar interpretation is given by A. Brunlechner 1 to the associated siderite and limonite at Hiittenberg in Carinthia. In this case, however, the waters charged with ferrous carbonate re- deposit it upon contact with limestones. Here also the original for- mation, the main ore body, is sedimentary. The following analyses represent mixed carbonates, mainly ferriferous: Analyses of mixed carbonates. A. Iron carbonate, Sunday Lake, Michigan. Analysis by W. F. Hillebrand. B. Iron carbonate, Penokee district, Michigan. Analysis by R. B. Riggs. C. Iron carbonate, Gunflint Lake, Canada. Analysis by T. M. Chatard. D. Ferrodolomite, Marquette district, Michigan. Analysis by G. Steiger. For analyses A, B, C, D, and others, see Bull. U. S. Geol. Survey No. 228, 1904, pp. 318-320. E. Cobaltiferous siderite, from a mine near Neunkirchen, Germany. Analysis by G. Bodlander, Neues Jahrb., 1892, Band 2, p. 236. F. Mangandolomite, Greiner, Tyrol. Analysis by K. Eisenhuth, Zeitschr. Kryst. Min., vol. 35, 1902, p. 582. Other analyses of dolomite, etc., are given in this paper. A B C D E F Insoluble 0. 16 Si0 2 28. 86 15. 62 23.90 26. 97 Ti0 2 . 20 None. AloOq 1. 29 4. 27 . 07 1. 30 Fc,o! 1. 01 8. 14 .44 2. 31 ^2 w 3 * FeO'. 37. 37 32. 85 10. 72 39. 77 45. 34 6. 59 MnO. .97 5. 06 .28 .29 23. 41 CoO.. 3. 85 CaO . 74 .81 22. 25 .66 1.21 10. 48 MgO 3. 64 2. 66 8. 52 1. 94 8. 80 14. 58 Alkalies .09 H 2 0 - } .68 } .68 None. . 10 H 2 0+ . 99 .51 PAY J Trace. .03 co 2 25. 21 30. 32 32. 42 26. 20 41. 55 45. 59 so 3 .17 99. 97 100. 41 99. 76 , 100. 17 100. 75 100. 81 SILICATED IRON ORES. In addition to siderite, certain sedimentary silicates serve as sources for limonite and hematite ores. Glauconite, for example, was sug- gested by B. A. F. Penrose 2 as a possible parent of iron ore, and a green silicate from which the Mesabi ores are derived was placed under glauconite by J. E. Spurr . 3 C. K. Leith , 4 however, in his report on the Mesabi district, has shown that the green mineral of the ferruginous cherts is not glauconite, but a hydrated ferrous or ferroso- 1 Zeitschr. prakt. Geologic, 1893, p. 301. 3 Ann. Rept. Geol. Survey Arkansas, vol. 1, 1892. This is a monograph on the iron ores of Arkansas. 3 Bull. No. 10, Geol. Nat. Hist. Survey Minnesota, 1894. * Mon. U. S. Geol. Survey, vol. 43, 1903, pp. 237-279. On the origin of these ores see also N. H. Winchell, Bull. Geol. Soc. America, vol. 23, 1912, p. 317. Winchell regards the greenalite granules as derived from volcanic sand. 574 THE DATA OF GEOCHEMISTRY. ferric silicate, containing no potassium. To this silicate he gives the name greenalite. Its composition, as shown by the analyses made by G. Steiger 1 in the laboratory of the United States Geological Survey, is not accurately determinable, for the green granules can not be mechanically separated from the enveloping chert. Three analyses of the portion of the rock soluble in hydrochloric acid gave the fol- lowing results, after union of like bases and recalculation to 100 per cent. For comparison with them, in a fourth column, I give an analy- sis by F. Field 2 of a green, massive, chloritic mineral associated with the cronstedtite of Cornwall: Analyses of greenalite , etc. Greenalite, Steiger. Cornwall, 1 2 3 Field. Si0 2 30. 08 30.49 38. 00 31. 72 Fe 2 0 3 34. 85 23. 52 8.40 18. 51 FeO 25. 72 36. 92 46. 56 39. 46 HoO 9. 35 9. 07 7. 04 11. 02 100. 00 100. 00 100. 00 100. 71 Field’s mineral and the greenalite No. 2 are very similar, and approach in composition a hydrated compound of the garnet type, Fe' ,/ 2 Fe ,/ 3 (Si0 4 ) 3 .3H 2 0. The third greenalite analysis, however, is of an almost entirely ferrous compound, a hydrous metasilicate approaching the formula FeSi0 3 .aq. It is evident that the abso- lutely definite silicate is yet to be identified. In the analyses cited the soluble green granules formed from 48 to 82.5 per cent of the entire greenalite rock, which, according to Leith, represents a marine sediment analogous to glauconite. From this sil- icate, by leaching, the hydrous hematites of the Mesabi district were concentrated; but the reactions proposed by Leith to account, first, for the greenalite and, later, for its decomposition are largely hypo- thetical. Iron, in solution as carbonate, was probably brought into the ocean by waters from the land and precipitated as ferric hydrox- ide. The latter compound, partly or wholly reduced to the ferrous state by organic matter derived from marine vegetation, then com- bined with silica, of which an excess, now represented by chert, was also present. These processes are possible, and the explanation thus offered to account for the iron-bearing rocks is probable enough to be provisionally held, at least until something better is offered. We know that ferruginous sediments are now forming in the ocean; we 1 See C. K. Leith, Mon. U. S. Geol. Survey, vol. 43, 1903, p. 246. Discussion by F. W. Clarke. 2 Philos. Mag., 5th ser., vol. 5, 1878, p. 52. SEDIMENTARY AND DETRITAL ROCKS. 575 know that chert, in many cases, is of organic origin; and these facts are consistent with the suppositions summarized above. At a number of European localities iron ores are found which con- sist partly of silicates. One of these, thuringite, is a member of the chlorite group ; but another chloritic mineral, chamosite, which occurs associated with magnetite, limonite, or hematite in oolitic aggrega- tions, is more definitely an ore of iron. Its composition, as deter- mined by C. Schmidt 1 on Swiss material, and by E. R. Zalinski 2 on Thuringian specimens, is represented by the empirical formula 3Fe0.Al 2 0 3 .2Si0 2 .3H 2 0. The much rarer mineral cronstedtite has probably the same formula, with ferric oxide in place of alumina; and it differs from greenalite, as represented by the second analysis of the latter, in containing one less molecule of silica. Berthierine, from Hayanges, near Metz, is essentially a mixture of chamosite and mag- netite, 3 and forms a valuable ore. These silicates all undergo alteration with great ease, yielding oxides or hydroxides of iron. In most cases the ores containing them are oolitic, and form beds of sedimentary origin. 4 In this respect they resemble glauconite and greenalite, with which, chemically, they are so closely allied. How they were formed is uncertain and differ- ent authorities interpret the evidence differently. The latest writer, E. R. Zalinski, 5 regards thuringite and chamosite as secondary prod- ucts, derived by alteration from earlier sediments at the bottom of the Lower Silurian sea. Whatever the final conclusion may be, it seems clear that glauconite, chamosite, and greenalite, and possibly other allied silicates, were all formed by similar reactions, different local conditions having determined which product should appear. 6 1 Zeitschr. Kryst. Min., vol.ll, 1886, p. 601. 2 Neues Jahrb., Beil. Band 19, 1904, p. 40. 2 See A. Lacroix, Min6ralogie de la France, vol. 1, p. 401, for this and other French occurrences. * On the ores, locally known as “minette,” of Luxemburg and Lorraine, see Bleicher, Bull. Soc. indust, de l’Est, 1894; L. Hoffman, Verhandl. Naturhist. Ver. preuss. Rheinlande u. Westfalens, vol. 55, 1898, p. 109; H. Ansel, Zeitschr. prakt. Geologie, 1901, p. 81; and L. van Werveke, idem, p. 396. On the Thur- ngian ores see H. Loretz, Jahrb. K. preuss. geol. Landesanstalt, 1884, p. 120. Much other literature is cited in the memoirs mentioned here. 6 Neues Jahrb., Beil. Band 19, 1904, p. 79. Zalinski gives a good summary of the various theories which have been framed in order to account for these ores. 6 In addition to the literature already cited, the following American reports on iron ores are worth noticing: W. B. Phillips, Iron making in Alabama, a bulletin issued by the Alabama Geol. Survey in 1908. S. W. McCallie, Bull. No. 10-A, Georgia Geol. Survey, 1900, on the brown iron ores of that State; H. B. C. Nitze, Bull. No. 1, North Carolina Geol. Survey, 1893; F. L. Nason, Report on iron ores, Mis- souri Geol. Survey, 1892; Rept. of Progress F, Second Geol. Survey Pennsylvania, 1878, on the ores of the Juniata Valley; E. T. Dumble, Reports on the iron-ore district of East Texas: Second Ann. Rept. Texas Geol. Survey, 1891. The most exhaustive general treatise is R. Beck’s great monograph, Die Ge- schichte des Eisens. Les minerais de fer oolitique de France, by L, Cayeux (Ministere trav. publ., Paris, 1909) is an important recent monograph. ) 576 THE DATA OF GEOCHEMISTRY. GYPSUM. The occurrence of gypsum as a sedimentary rock has already been partially considered. 1 It may form on a large scale during the con- centration of oceanic and other natural brines, and it is sometimes deposited from solution in fresh waters. Acid waters of volcanic origin, 2 or derived from the oxidation of pyrite, by acting upon limestones, also produce gypsum. Its appearance as an accessory mineral in dolomitization is due to double decomposition between limestone and solutions containing magnesium sulphate; and other sulphates may act in a similar way. L. Jowa, 3 for example, prepared crystals of selenite by acting upon chalk with a solution of ferrous sulphate. Gypsum formed by reactions of this order, however, is commonly dissolved by the waters which assist in the process, and is carried away, to be diffused or deposited elsewhere. As an important rock gypsum is generally a saline residue, and its formation in the first instance is probably oftener due to the action of oxidizing pyrite upon lime-bearing rocks than to any other cause. 4 NATIVE SULPHUR. Native sulphur is a frequent companion of gypsum, and this, too, may be produced in several ways. It is known as a volcanic subli- mate and is a product of reactions between sulphur dioxide and hydrogen sulphide. It is also formed by the incomplete combustion of hydrogen sulphide, probably in accordance with the equation 5 2H 2 S + 0 2 = 2H 2 0 + 2S. According to Becker, who studied the phe- nomena at Sulphur Bank, California, the oxidation of H 2 S to H 2 S0 4 develops 201,500 calories. The oxidation to H 2 0 + S develops only 59,100 calories. Hence, where oxygen is in excess, as at the surface, hydrogen sulphide is completely oxidized, and sulphuric acid is formed. A short distance below the surface oxygen is deficient, and then sulphur is liberated. Probably, however, the actual conditions are more complex. Sulphur dioxide must be produced to some ex- tent, and that reacts with the hydrogen sulphide to form sulphur also. At all events, sulphuric acid and free sulphur both occur at Sulphur Bank, and in accordance with the conditions imposed by 1 See ante, pp. 211-232. 2 J. W. Dawson (Acadian geology, 1891, p. 262) attributes the formation of gypsum in Nova Scotia to the action of sulphuric acid, derived from volcanic sources, on limestones. s Annales Soc. g6ol. Belgique, vol. 23, 1896, p. cxxvii. * For data upon American gypsum see G. P. Grimsley, Michigan Geol. Survey, vol. 9, pt. 2, 1904; Grimsley and E. H. S. Bailey, Kansas Univ. Geol. Survey, vol. 5, 1899; C. R. Keyes, Iowa Geol. Survey, vol. 3, pp. 257-304; F. J. H. Merrill, Bull. New York State Mus., vol. 3, No. 11, 1893. Bull. U. S. Geol. Survey No. 223, 1904, by G. I. Adams and others, describes the gypsum deposits of the United States. On the genetic relations of gypsum and anhydrite see R. C. Wallace, Geol. Mag., 1914, p. 271. 5 See G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, p. 254; and J. Habermann, Zeitschr. anorg.' Chemie, vol. 38, 1904, p. 101. SEDIMENTARY AND DETRITAL ROCKS. 577 theory. The deposition of sulphur at the Rabbit Hole mines, Ne- vada, is also ascribed by G. I. Adams 1 to solfataric activity. Sulphur deposits are common around mineral springs, being due to the imperfect oxidation of hydrogen sulphide; and the latter com- pound may be generated either by the action of acid waters upon sulphides or through the reduction of sulphates, such as gypsum, by micro-organisms . 2 The interpretation of any given locality for sulphur is not easy, for different conditions reign in different places. In one deposit the evidence of thermal reduction may be clear, while elsewhere some other process is seen to have been operative. The most famous of all sulphur deposits is that near Girgenti, in Sicily, and this has been variously interpreted. Gypsum, sulphur, celestite, and aragonite are here intimately associated, in what is evidently a sedimentary formation not far removed from a center of great vol- canic activity. The sulphur, therefore, has been regarded by some writers as volcanic, by others as a product of nonvolcanic agencies, and the conditions are such that either supposition can be strongly supported. Sicily abounds in solfataras, and in springs charged with hydrogen sulphide; and these may well have brought the sulphur from volcanic sources far below the surface. Its deposition, in that case, is due to the decomposition of hydrogen sulphide, which has taken place under aqueous rather than igneous conditions; and this view, with differences in detail, has been adopted by various author- ities . 3 A. von Lasaulx , 4 for example, has argued that the sulphur was deposited from waters containing hydrogen sulphide and cal- cium carbonate during concentration in fresh-water basins; and G. Spezia 5 has developed a similar argument more fully. In order to account for the association of sulphur and gypsum without assuming the derivation of one from the other, Spezia cites an observation of A. Bechamp , 6 who found that when hydrogen sulphide was passed into water containing suspended calcium carbonate the latter was partly decomposed and calcium hydrosulphide was formed. This experiment was repeated by Spezia , 7 but with fragments of marble and under a pressure of six atmospheres. The solution thus obtained was found to contain a sulphide, and upon evaporation to small 1 Bull. U. S. Geol. Survey No. 225, 1904, p. 497. See also D. F. Hewett on Sulphur deposits in Wyoming, Bull. U. S. Geol. Survey No. 540-R, 1913. 2 See especially E. Plauchud, Compt. Rend., vol. 84, 1877, p. 235; vol. 95, 1882, p. 1363. Also A. Etard and L. Olivier, idem, vol. 95, 1882, p. 846. 3 R. Travaglia (Bol. Com. geol., 1889, p. 110), however, regards the Sicilian sulphur as having been formed through the reduction of gypsum by organic matter, the remains of marine animals. * Neues Jahrb., 1879, p. 490. 6 Sull’ origine del solfo nei giacimenti solfiferi della Sicilia, Torino, 1892. The theories relative to the origin of Sicilian sulphur are exhaustively summed up and discussed in this memoir. Several Italian works cited by Spezia I have not been able to consult. For a general paper on the origin of sulphur, see O. Stutzer, Econ. Geology, vol. 7, 1912, p. 732. * Annales chim. phys., 4th ser., vol. 16, 1869, p. 234. 7 Op. cit. ,p. 119. 97270°— Bull. 616—16 37 578 THE DATA OF GEOCHEMISTRY. bulk at ordinary temperatures it deposited microscopic crystals of calcite, sulphur, and gypsum. By a reaction of this kind, between the sedimentary limestones and the ascending sulphureted waters, the observed association of minerals may have been produced. Wherever such waters act slowly upon limestones free sulphur with gypsum is likely to be formed. 1 It must be observed, however, that the partial oxidation of hydrogen sulphide in presence of limestone would also produce the same association of substances. It is inter- esting to note that in a large crystal of gypsum from Cianciana, H. Sjogren 2 found a fluid inclusion which yielded liquid enough for analysis. Its composition resembled that of sea water, and the cavity also contained hydrogen sulphide. The considerable deposits of sulphur found in western Texas are also associated with gypsum, and with waters which contain hydro- gen sulphide. Some waters from the sulphur beds are strongly acid, and E. M. Skeats 3 reports one water which carried 1,360 parts per million, or 79.08 grains per gallon, of free H 2 S0 4 . The deposits are associated with limestones, which are sometimes bituminous, and at some points, as described by Richardson, gypsum has evidently been formed by alteration of the carbonate. At Cove Creek, in Utah, sulphur occurs in great quantities as an impregnation in rhyolitic tuff. 4 It is derived from hydrogen sulphide of volcanic origin, and is also accompanied by strongly acid water. So far as the sedi- mentary rocks are concerned, the association of limestone, gypsum, sulphur, and hydrogen sulphide seems to be quite general, although not absolutely invariable. The association of sulphur with petroleum or bituminous matter is also common. CELESTITE. Celestite, the sulphate of strontium, SrS0 4 , is another mineral of the sedimentary rocks, which also occurs in Sicily with the gypsum and sulphur. It is one of the most characteristic minerals of the Sicilian deposits. In Monroe County, Michigan, according to E. H. Kraus and W. F. Hunt, 5 6 the celestite is found disseminated through dolomite, and the upper layer of the rock at the point especially studied contained over 14 per cent of the strontium com- 1 Other examples are given by R. Brauns, Chemische Mineralogie, p. 366. L. Dieulafait (Compt. Rend., vol. 97, 1883, p. 51), has suggested that polysulphides of calcium and strontium may assist in the formation of sulphur deposits. 2 Bull. Geol. Inst. Upsala, vol. 1, No. 2, 1893. A similar inclusion was earlier described by O. Silvestri, Gazz. chim. ital., vol. 12, 1882, p. 2. 3 Bull. Univ. Texas Mineral Survey No. 2, 1902. See also G. B. Richardson, idem, No. 9, 1904, p. 68. The sulphur deposits of Louisiana are described by L. Baldacci, 11 giacimento solfifero della Louisiana, Rome, 1906. * See W. T. Lee, Bull. U. S. Geol. Survey No. 315, 1907, p. 485. For an earlier description, see G. vom Rath, Neues Jahrb., 1884, Band 1, p. 259. 6 Am. Jour. Sci., 4th ser., vol. 21, 1906, p. 237. See also W. H. Sherzer, idem, 3d ser., vol. 50, 1895, p. 246, and Michigan Geol. Survey, vol. 7, pt. 1, 1900, p. 208. SEDIMENTARY AND DETRITAL ROCKS. 579 pound. Below this layer there is a porous stratum, with cavities containing celestite and free sulphur. The latter is found in consid- erable quantities, and is evidently derived by reduction from the sulphate. Kraus 1 has also reported celestite as extensively dissemi- nated through dolomitic limestone near Syracuse, New York. At Put-in Bay, Lake Erie, the limestones contain disseminated celestite, and caverns exist which are lined with crystals of that mineral. 2 The celestite here has evidently been leached out from the surround- ing rocks and redeposited in the cavities. Although strontium sul- phate is much less soluble than gypsum, it is more soluble than calcium carbonate, and therefore it may be dissolved away from the latter. In Transylvania, according to A. Koch, 3 celestite and barite occur together in bituminous limestone. H. Bauerman and C. Le Neve Foster 4 report celestite in a nummulitic limestone in Egypt, and the crystals sometimes inclose fossil remains. It also appears as filli ng the interior of fossil shells, especially the chambers of nautili. At Condorcet, in France, as described by Lachat, celestite is found associated with gypsum in limestone. 5 Examples of this kind might be multiplied almost indefinitely. Strontium and calcium are so nearly related chemically that their common association in rocks is something to be naturally expected. BARITE. Barite, the barium sulphate, BaS0 4 , is closely akin mineralogically to celestite, but is more characteristically found in metalliferous veins than in bedded formations. 6 Its occurrence as a cement in sandstones has already been noticed, 7 and it has also been observed as a sintery or even stalactitic deposit from spring and mine waters. 8 P. P. Bedson 9 found barium to be present in notable amounts in an English colliery water; and T. Richardson 10 has described a deposit of barite from a similar solution. Like deposits from other English collieries have been reported by F. Clowes, 11 who analyzed samples containing from 81.37 to 93.35 per cent of BaS0 4 . The pipes carrying water from the mines which yielded these sediments were often choked by them, the barium sulphate being rarely absent 1 Am. Jour. Sci., 4th ser., vol. 18, 1904, p. 30. On celestite deposits in California, see W. C. Phalen, Bull. U. S. Geol. Survey No. 540, 1914, p. 521. 2 Kraus, Am. Jour. Sci., 4th ser., vol. 19, 1905, p. 286. 3 Min. pet. Mitt., vol. 9, 1888, p. 416. 4 Quart. Jour. Geol. Soc., vol. 25, 1869, p. 40. 6 Annales des mines, 7th ser., vol. 20, 1881, p. 557. 6 See L. Dieulafait, Compt. Rend., vol. 97, 1883, p. 51. 7 See ante, p. 539. 8 For the distribution of barium in waters, etc., see R. Delkeskamp, Notizbl. Ver. Erdkunde, 4th ser., Heft 21, 1900, pp. 47-83. On the distribution of barium and strontium in sedimentary rocks, see L. Collot, Compt. Rend., vol. 141, 1905, p. 832. 9 Jour. Soc. Chem. Ind., vol. 6, 1887, p. 712. 10 Rept. Brit. Assoc., 1863, p. 54. 11 Proc. Roy. Soc., vol. 46, 1889, p. 368. 580 THE DATA OF GEOCHEMISTRY. and frequently their chief constituent. At Doughty Springs, in Delta County, Colorado, according to W. P. Headden , 1 large masses of sinter have formed, consisting at some points of nearly pure barium sulphate, which at other points is mixed with minor to domi- nant quantities of calcium carbonate. Barytic sinters are also formed by a brine spring in a mine at Lautenthal, in the Hartz Mountains, and these have been carefully studied by G. Lattermami . 2 In this case they are precipitated by the mingling of the sulphate-bearing mine waters with the brine from the spring. Lattermann’s analyses of the two waters, as stated by him in grams per liter, are as follows: Analyses of spring and mine waters at Lautenthal. Spring. Mine water. BaCl 2 0.318 SrCl 2 . 899 CaCl 2 10. 120 1. 515 MeCl, 4. 360 .023 NaCl 68. 168 4. 533 KC1 .458 MffSCh .652 ZnS0 4 .015 The barytic deposits from these waters contain strontium, and appear in several forms — as stalactites, as mud, and as incrustations. Analyses of them by Fernandez and Bragard show the subjoined proportions of the two principal ingredients . 3 Barium and strontium sulphates in deposits at Lautenthal. White stalac- tities. Brown stalac- tities. Mud. Crusts. BaS0 4 84. 81 12.04 83. 88 8. 64 82.3 13.4 92. 44 4. 32 SrS0 4 Similar mixtures of the two sulphates intermediate between barite and celestite are well known in crystalline form, and calcium sulphate is often present also. A remarkable banded barite, from Pettis County, Missouri, described by C. Luedeking and H. A. Wheeler , 4 had the following composition : i Proc. Colorado Sci. Soc., vol. 8, 1905, p. 1. * Jahrb. K. preuss. geol. Landesanstalt, 1888, p. 259. A similar deposit of barium and strontium sulphates from an English mine water is described by J. T. Dunn, Chem. News, vol. 35, 1877, p. 140. a Complete analyses are given in the original memoir by Lattermann. 'Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 495. The presence of ammonium salts was independently verified by tests in the laboratory of the United States Geological Survey. SEDIMENTARY AND DETRITAL ROCKS. 581 Analysis of barite from Pettis County , Missouri. BaS0 4 87.2 SrS0 4 10.9 CaS0 4 2 (NH 4 ) 2 S0 4 2 H 2 0 2.4 100.9 The presence of an ammonium salt in such a mineral is most unusual. Nearly or quite all of the occurrences of barite indicate that it is a mineral of aqueous origin. It may form as a direct deposit from waters, or as a precipitate when different waters commingle, or, as C. W. Dickson 1 has shown, by a reaction between solutions of barium bicarbonate and gypsum. Barium sulphate is also produced, accord- ing to Dickson, when the bicarbonate solution is brought into contact with oxidizing pyrite; and its presence in limestones is attributed to a possible coincidence of the two reactions. The oxidizing pyrite is first instrumental in transforming calcium carbonate to sulphate, and the latter then undergoes double decomposition with the percolating barium solutions. The original source of the barium is in the feld- spars and micas of the crystalline rocks, from which it is dissolved out during the ordinary process of weathering. One very different occurrence of barite remains to be mentioned. In the Salem district of India T. H. Holland 2 found a remarkable network of veins consisting of quartz and barite, with about 70 per cent of the first mineral and 30 of the second. These veins are mostly in pyroxenic gneiss, and one cuts a dike of augite diorite, and Holland, for structural reasons, regarded the quartz-barite rock as a segregation from the original magma. This supposition, how- ever, is chemically improbable. In a molten state quartz (or free silica) would react upon barium sulphate, to form a silicate and set sulphuric acid or sulphur dioxide free. Quartz and barite are mag- matically incompatible. 3 Various syntheses of crystalline barite are on record. One of the latest by Hilda Gebhart, 4 is worth noting. Solid barium chloride was covered by a layer of gelatinous silica, over which a solution of a sulphate was placed, and the apparatus was allowed to stand undis- turbed for eight or nine months. By slow diffusion of the sulphate through the intervening siliceous jelly definite crystals of barite were formed. 1 School of Mines Quart., vol. 23, 1902, p. 366. 2 Rec. Geol. Survey India, vol. 30, 1897, p. 236. a On the genesis of barite see an important paper by G. B. Trener, Jahrb. K.-k. geol. Reichsanstalt, vol. 53, 1908, p. 387. This paper contains abundant literature references. On the barite deposits of Virginia see T. L. Watson, Bull. Am. Inst. Min. Eng., 1907, p. 953. 4 Min. pet. Mitt., vol. 29, 1910, p. 185. 582 THE DATA OF GEOCHEMISTRY. FLUORITE. Fluorite or fluorspar, calcium fluoride, CaF 2 , is also a common mineral in dolomites and limestones , 1 and it is often associated with galena and zinc blende. Crystals of it are found in limestone geodes, where it has evidently been deposited from solution. In some oases it may have been formed by fluoride solutions percolating through and replacing limestone. Its commonest occurrence is as a filling of veins . 2 1 See ante, p. 335, for an account of fluorite as a rock-forming mineral. Also p. 539 for fluorite as a cement in sandstones. For an exhaustive memoir on fluorite in sediments see K. Andrde, Min. pet. Mitt., vol. 28, 1909, p. 585. 2 For a description of the great fluorspar deposits in Kentucky and southern Illinois see S. F. Emmons, Trans. Am. Inst. Min. Eng., vol. 21, 1893, p. 31; H. F. Bain, Bull. U. S. Geol. Survey No. 255, 1905; E. O. Ulrich and W. S. T. Smith, Prof. Paper U. S. Geol. Survey No. 36, 1905; and F. J. Fohs,Econ. Geology, vol. 5, 1910, p. 377. On the fluorspar of Derbyshire see W. M. Egglestone, Trans. Inst. Min. Eng., vol. 35, 1908, p. 236; and C. B. Wedd and G. C. Drabble, idem, p. 501. The latter paper contains a good bibliography. On the fluorspar of San Roque, Cordoba, Argentina, see J. Valentin, Zeitschr. prakt. Geologie, 1896, p. 104. CHAPTER XIV. METAMORPHIC ROCKS. METAMORPHIC PROCESSES. In its widest sense the adjective metamorphio may be applied to any rook that has undergone any sort of change. Practically, how- ever, it is used to describe a well-defined class of rocks in which the transformation from an original form has been nearly complete. A slightly altered igneous or sedimentary rock is not commonly called metamorphic; neither is a mass of decomposition products so desig- nated. The gneisses, the schists, quartzite, marble, and serpentine are the most familiar examples of metamorphism, and in each case an antecedent rock has been changed into a new rock by one or sev- eral among many different processes. 1 Some varieties of metamorphism are entirely physical or structural, and therefore will not be considered in this memoir. Metamorphoses which represent only a development of slaty or schistose structure are of this kind. In most oases, however, metamorphism is accom- panied by chemical changes, which are indicated by the production of new minerals, and this sort of metamorphism concerns us now. It may be regional, when large areas are affected, or a phenomenon limited to a contact between two reacting rocks, but these distinc- tions are of little significance chemically. The chemical phases of the process are all that we need to consider at present. The reactions involved in metamorphism are not difficult to classify. The following changes are probably the most important: 1. Molecular rearrangements, as in the process of uralitization, when a pyroxene rock is changed into one characterized by amphibole. 2. Metamorphism by hydration. The conversion of a peridotite or pyroxenite into serpentine is a case of this kind, although some- thing more than simple hydration is involved in the change. 3. Metamorphism by dehydration. The change of limonite to hematite and of bauxite to emery are good examples. Alterations of this class, however, are often more profound than dehydration alone can account for, especially when they take place at high tem- peratures. Then the molecules of hydrous minerals may be broken 1 On the application of physicochemical methods to problems of metamorphism, see J. Johnston and P. Niggli, Jour. Geology, vol. 21, pp. 481, 588, 1913. The paper is essentially theoretical, with few references to specifically geologic phenomena. 583 584 THE DATA OF GEOCHEMISTRY. down, as when serpentine breaks up into olivine and enstatite, or talc into a metasilicate and quartz. 4. Oxidations and reductions, which affect chiefly the iron oxides of the rocks. Ferrous compounds become ferric, and hematite, on the other hand, may be reduced to magnetite. 5. Changes other than hydration, produced by percolating solu- tions. Cementation is one process of this kind, and the change from sandstone to quartzite is a common example of it. In other processes the solutions effect chemical transformations, and develop new com- pounds. The dolomitization of limestone is a case in point. 6. Metamorphism by the action of gases and vapors, the so-called “ mineralizing agents.” These agents generate new minerals within a rock, and like solutions introduce new constituents. 7. Metamorphism by igneous intrusions. This heading covers the changes due to the intrusion of molten matter into or between rock masses, whereby a class of “contact minerals” is formed. Although this classification is simple, it is only superficially so. It is useful as a matter of convenience, but its application to concrete examples of metamorphism is not always easy. Two or more proc- esses may operate simultaneously, or they may shade into one an- other, with all sorts of variations in detail due to variations in tem- perature and pressure. All of these considerations must be borne in mind in dealing with the actual phenomena of metamorphism. The ideal simplicity is not often found. In the study of metamorphic phenomena the conceptions developed by C. R. Van Hise 1 are also helpful. Van Hise divides the litho- sphere into two zones — an upper zone of katamorphism and a lower of anamorphism. The zone of katamorphism is furthermore sub- divided into two belts — one the belt of weathering, the other that of cementation. These approximately concentric shells are character- ized by definite chemical differences, which may be briefly sum- marized as follows : The uppermost shell of all, the belt of weathering, extends from the surface of the ground to the level of the ground water, and its thickness is very variable. It is essentially the region of rock decom- position, and its reactions are mainly those of hydration, oxidation, absorption of carbonic acid with liberation of silica, and losses of material by leaching. It is also a region of low pressure, relatively low temperature, and great porosity. In it the complex silicates are broken down into simpler compounds, from which, within the belt, they are rarely regenerated. The belt of cementation is that which contains the ground water. Its rocks are more or less porous and fractured, its temperature is still not high, but the pressure is great enough to play an important 1 A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904. METAMORPHIC ROCKS. 585 part in the reconsolidation of sedimentary material. It is, in short, the birthplace of such rocks as shales and sandstones. In the belt above it solution is a leading process, but here, in the accumulated ground water, redeposition rules. Hence its name, the belt of cemen- tation. In the zone of anamorphism, which lies below the region of the ground water, the rocks are no longer distinctly porous. The pres- sure above them tends to close up all pores and fractures. The tem- perature is also relatively high — that is, below the melting point of the rocks, but possibly above the critical temperature of water. Under these conditions the reactions of the upper zone are reversed. Instead of hydration, there is dehydration; reduction is more com- mon than oxidation; carbonates are decomposed and silicates are regenerated. Pneumatolytic reactions are characteristic of this region, and so too are metasomatic changes. There is also a tendency to the development, under pressure, of the heavier and denser rock- forming minerals, and of the species which contain constitutional water, fluorine, or boric oxide. Garnet, staurolite, muscovite, epi- dote, and tourmaline are, for example, typical minerals of the meta- morphic rocks . 1 According to C. R. Van Hise, the minerals of the upper zone are those which are formed with increase of volume and evolution of heat. In the lower zone, contraction and absorption of heat occur. These distinctions, of course, are general, not absolute, and should only be accepted in a broad way. They stand for prevailing tend- encies, to which many exceptions are possible. Nor can the belts and zones be rigorously delimited, for they shade into and even interpenetrate one another. Material formed in the belt of weather- ing is covered up by sediments, and presently finds itself within the belt of cementation. Still later, covered more deeply, it may pass into the zone of anamorphism. So also, by erosion, a part of the anamorphic zone may be uncovered and brought within the realm of weathering. To all of these changes chemical changes correspond, so that the same mass of material can be metamorphosed, in opposite directions, over and over again. A clay becomes a shale; that is transformed into a schist or gneiss, and that again may pass back into clay. The phenomena of decomposition, of reconsolidation, and of recrystallization form parts of a cycle of changes which are recog- nized mainly by their interruptions. The definite products to which we give definite names represent temporary stoppages or periods of slow change in the progress of the cycle. 1 According to G. Spezia (Atti Accad. sci. Torino, vol. 46, p. 682; and Chem. Abstracts, vol. 6, p. 2587, 1912) the views of Van Hise relative to the influence of pressure are untenable. For instance, limonite, held for 8 months under a pressure of 8,000 atmospheres was not dehydrated. Neither, under 7,000 atmos- pheres, was aragonite transformed to calcite. For a general discussion of the effects of pressure on the physical and chemical relations of solids, see J. Johnston and L. H. Adams, Am. Jour. Sci., 4th ser., vol. 35, 1913, p. 205. 586 THE DATA OF GEOCHEMISTRY. In both zones of the lithosphere water is the chief agent of chem- ical metamorphism. It is most abundant in the zone of katamor- phism, where it acts mainly as a liquid and fills more or less com- pletely the pore spaces of the rooks. In the zone of anamorphism water is much less abundant and operates in the subcapillary and intermolecular spaces, where, because of the higher temperatures, it is probably present, at least for the most part, as vapor. At a depth of about 10 kilometers the critical temperature of water is likely to be reached, and its chemical activity should then be very high. The well-known corrosive action of superheated steam upon glass is an illustration of this point. Even when the water is still liquid, at temperatures of over 200°, it may form a fluid or pasty mass with some silicates, as was shown by C. Barus 1 in his experiments upon aqueo-igneous fusion. In the zone of katamorphism the water is moving freely, percolat- ing from place to place. In the lower zone its mobility must be much diminished, so that on a given particle of rock it acts for a longer time. It may appear in this zone, according to Van Hise, in three ways — as water held by buried sedimentaries, as water liberated from hydrous compounds by heat or pressure, and as magmatic water contained in igneous intrusions. But from whatever source it may be derived, its chemical functions are the same. It acts as a solvent upon practically all the rock-forming minerals; it therefore trans- fers matter slowly from point to point and in that way assists in bringing about recrystallization. In so doing the water is partly taken up into the molecules of new compounds, such as staurolite, epidote, mica, and tourmaline, of which it forms a constitutional part and from which it can only be expelled at temperatures ap- proaching or even exceeding a red heat. Loosely combined water thus becomes firmly combined water and ceases for the time being to be further active. A reference back to the chapter upon rock-form- ing minerals will show how many syntheses have depended upon heating the constituent substances with water under pressure. The minerals thus formed are characteristic of the zone of anamorphism, even though they are not confined to it. 2 The sediments, as a rule, contain organic matter. When they reach, by burial, the high temperatures of this zone, the organic matter is decomposed, yielding free carbon, carbon dioxide, nitrogen, and water. The free carbon may appear in the metamorphosed rocks as amorphous particles or it may be recrystallized into graphite; the 1 See ante, p. 297. 2 In addition to works already cited, the following papers which have appeared during recent years on hydrothermal syntheses deserve notice: E. Baur, Zeitschr. anorg. Chemie, vol. 72, 1911, p. 119. W. T. Muller and J. Konigsberger, Zeitschr. angew. Chemie, vol. 25, 1912, p. 1273. P. Niggli, Zeitschr. anorg. Chemie, vol. 84, 1913, p. 31. G. W. Morey and P. Niggli, Jour. Am. Chem. Soc., vol. 35, 1913, p. 1086. M. Schlaeppfer and P. Niggli, Zeitschr. anorg. Chemie, vol. 87, 1914, p. 52. METAMORPHIC ROCKS. 587 carbon dioxide may escape, working its way slowly upward, or it may be caught and inclosed within crystals of quartz or other minerals. Inclusions of this kind are common, and so also are inclusions of free carbon. In this process of decomposition the organic matter of the sedi- ments acts as a reducing agent, transforming ferric to ferrous com- pounds. When magnetite is thus formed from limonite, the reduction is partial, but when the iron compounds of a clay are metamorphosed into staurolite or tourmaline, the change from ferric to ferrous is nearly or quite complete. It must not be assumed, however, that organic matter is the only reducing agent during metamorphism. We have seen in a previous chapter that hydrogen may be either occluded in or generated from heated rocks , 1 and its activity as a reducer may be very great. But on this point, geologically speaking, there is little positive knowledge. We are compelled to deal, more or less, with reasonable inferences. By the action of the heated waters much silica is liberated, which recrystallizes in part as quartz. Some of it, however, attacks the limestones of the buried sedimentaries, liberating carbon dioxide and forming silicates, such as wollastonite. When, however, a large mass of fairly pure limestone or dolomite reaches the anamorphic zone, it is recrystallized into marble. This change, and also the formation of dolomite, was considered in detail in the preceding chapter, where the subject was perhaps out of place. Some of the concomitant changes will be discussed later. One great distinction between the tw’o zones remains to be noted. In the belt of weathering the transfer of material from point to point, both by mechanical and by chemical means, is a conspicuous feature. In the belt of cementation the mechanical transfers become less prom- inent, but the moving waters carry much matter long distances in solution. In the zone of anamorphism the mechanical movements become relatively insignificant and the chemical changes are prac- tically effected in place — that is, the chemical movements of matter within the lower zone are only through trifling distances, and the transformations are effected with material close at hand. The upper zone is, then, emphatically a zone of mobility; while the material of the lower zone, being under great pressure, is comparatively immov- able. I speak now, of course, of certain kinds of movement; the motions of the earth’s crust, its upheavals and depressions, the dis- placing influence of igneous intrusions, etc., are phenomena of a dif- ferent order. Neither do I use the terms movable and immovable in any absolute sense, for they have only a relative meaning. The freedom of motion in the upper zone is vastly greater than in the See ante, p. 275 et seq., for the experiments of Tilden, Travers, Gautier, etc. 588 THE DATA OF GEOCHEMISTRY. lower; and because of that fact the phenomena of the two zones become strongly contrasted. CLASSIFICATION. The classification of the metamorphic rocks is not a simple matter. The criterion of structure is not sufficiently general, and that of genesis is too vague. We can not always determine the genesis of a given rock, and when we are able to do so, the result, for purposes of classification, may be unsatisfactory. A gneiss can be derived from an igneous rock or from one of sedimentary origin, the product being sensibly the same in both cases. It is possible, of course, to classify these rocks on the basis of their composition; but here again there are difficulties, even greater, perhaps, than those which becloud the classification of purely igneous material . 1 Quite dissimilar rocks may have very similar composition. In fact, no single classifica- tion covers all the ground; for the phenomena of nature do not arrange themselves in linear sequence. They form an irregular net- work of interlacing lines, with all manner of intersections and fre- quent disturbances. Taking all of the difficulties into account, I prefer to study the metamorphic rocks, so far as may be practicable, with reference to the chemical processes which have governed their formation. I have already stated that several processes may take part in a single metamorphosis; but in many cases one process predominates. The conspicuous process, then, gives a basis for classifying our data which need not, however, exclude other arrangements for other pur- poses. The method supplements, but does not supplant its rivals. For convenience we may also divide the metamorphic rocks into three classes, as follows: First, those derived from igneous rocks; second, those of sedimentary origin; third, rocks formed by contact reac- tions between the igneous and the sedimentary. The metamorphism of the igneous rocks is commonly a deep-seated phenomenon; that is, its conspicuous examples are formed in the zone of anamorphism, or under anamorphic conditions. Leaving mechanical or structural changes out of consideration, its conspicu- ous feature is of the order of a molecular rearrangement; in other words, the older minerals are transformed into new species, some- times by simple paramorphism and sometimes with transfer of material from one molecule to another. In general, as F. Becke 2 has shown, the rearrangements are attended by decrease of volume, the product of the change being denser than the original material. >U. Grubenmann (Die Kristallinen Schiefer, Berlin, vol. 1, 1904; vol. 2, 1907) has attempted to form a chemical classification of the schists, which resembles Osann’s discussion of the igneous rocks. A second edition of Grubenmann’s book in one volume appeared in 1910. The references in this work are to the first edition. On metamorphic rock series see P. Niggli, Min. pet. Mitt., vol. 31, 1912, p. 477. s Neues Jahrb., 189G, Band 2, p. 182. METAMORPHIC ROCKS. 589 For example, in the special case chosen by Becke, the plagioclase and orthoclase of a rock containing a little water were transformed into a mixture of albite, zoisite, muscovite, and quartz, the volume reduc- tion being in the ratio of 547.1:462.5, a loss of over 15 per cent. A number of similar condensations are cited by U. Grubenmann; 1 and although the calculations are necessarily crude, they are none the less conclusive. 2 The fact that there are exceptions to the rule does not destroy its general validity. From a mineralogical point of view, the more noteworthy meta- morphoses within the igneous rocks may be classified under the following headings : 1. Change of pyroxene to amphibole. 2. Change of feldspar to mica. 3. Change of feldspar to zoisite. 4. Change of feldspar to scapolite. 5. Formation of epidote. 6. Formation of garnet. 7. Change of hornblende to chlorite. 8. Segregation of albite from plagioclase. 9. Formation of serpentine. 10. Alteration of ilmenite. This schedule is by no means exhaustive, for many other minor changes are to be observed in the metamorphism of igneous rocks. Every primary mineral that they contain may give rise to secondary species, and these represent all orders of transformation from the slightest modification to the complete molecular breaking down which is seen in the processes of weathering. Decompositions, how- ever, are not now under discussion; we are dealing with the phe- nomena of recrystallization within rock masses, excepting, of course, the case of serpentinization, which is a process of a different order. URALITIZATION. The alteration of pyroxene rocks into hornblende rocks is one of the best-established metamorphoses. The hornblende thus produced, when fibrous, is known as uralite, and the change is called uralitiza- tion. 3 It is often accompanied and complicated by other changes, such as the formation of epidote or zoisite, and it may also be coinci- dent with the development of a schistose structure. Mediosilicic and subsilicic rocks, like gabbro and diabase, are thus metamorphosed into amphibolite or hornblende schist. An excellent example of this sort 1 Die Kristallinen Schiefer, Berlin, 1904, pp. 34-38. Grubenmann’s data are taken from a paper by F. Becke, in Compt. rend. IX Cong. gdol. internat., 1903, p. 553. See also F. Loewinson- Lessing, Studien fiber die Eruptivgesteine: Compt. rend. VII Cong. g&>l. internat., St. Petersburg, 1897. 2 For a tabulation of the volume changes attending tho alteration of minerals, see C. R. Van Ilise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 397-408. 3 See G. H. Williams, Bull. U. S. Geol. Survey No. 62, 1890, p. 52, for a full discussion of this subject, accompanied by abundant references to literature. See also L. Duparc and T. Hornung, Compt. Rend., vol. 139, 1904, p. 223, on a theory of uralitization. 590 THE DATA OE GEOCHEMISTRY. of change was found by J. J. H. Teall 1 in a dike at Scourie, Suther- landshire, Scotland, where a dolerite had changed, first into a mas- sive hornblende-bearing rock and later into a schist. The following analyses will serve to illustrate the character of the changes thus produced : Analyses of 'pyroxene rocks before and after alteration. Aa. The plagioclase-pyroxene rock of the Scourie dike. Ab. The derived hornblende schist. Analyses A by Teall, loc. cit. Ba. Pyroxene from the center of a crystal, Templeton, Canada. Bb. Intermediate portion of the same crystal. Be. Hornblende forming the rim of the crystal. Analyses B by B. 7. Harrington, Geol. Survey Canada, Rec. of Progress, 1877-78, p. 21 G. Ca. Diallage from a gabbro, Transvaal, South Africa. Cb. Uralite from alteration of the diallage. Analyses C by P. Dahms, Neues Jahrb., Beil. Band 7, 1891, p. 99. Aa. Ab. Ba. Bb. Be. Ca. Cb. Si0 2 47.45 49.78 50. 87 50. 90 52. 82 53.53 52.73 ALOo 14.83 13.13 4.57 4.82 3.22 3.12 4.70 Fe 2 0 3 2.47 4.35 .97 1.74 2.07 5.09 5.26 FeO 14.71 11.71 1.96 1.36 2.71 13.54 10.21 MnO .15 .15 .28 MgO 5.00 5.40 15.37 15.27 19.04 18.77 12.59 CaO 8.87 8.92 24.44 24. 39 15. 39 6.19 12.58 Na 2 0 2.97 2.39 .22 .08 .90 .50 .23 K 2 0 .99 1.05 .50 .15 .69 .20 .06 H 2 0 1.00 1. 14 « 1.44 a 1.20 a 2. 40 1.54 Ti0 2 1.47 2.22 CO, .36 .10 Specific gravity 100. 12 3.10 100. 19 3.10 100. 49 3.181 100. 06 3.205 99.52 3.003 101. 01 99.90 a Loss on ignition. That the change from pyroxene to uralite or amphibole is something more than a paramorphism these few analyses clearly show. In A there has been oxidation of ferrous to ferric iron, in B a loss of lime, and in C a loss of magnesia. In many cases uralitization is accom- panied by a separation of magnetite , 2 and the lime removed reappears as calcite. Epidote is also a common product during the process, which must vary with variations in the composition of the altering rock and of the individual pyroxene. Augite thus yields hornblende or actinolite; diopside may change into tremolite, and from the soda pyroxenes the aluminous glaucophane may be derived. The com- position of the pyroxene is reflected in that of its derivative, but the augite-hornblende change is the most common . 3 Between the 1 British petrography, 1888, p. 198; also in Quart. Jour. Geol. Soc., vol. 41, 1885, p. 137. 2 See G. Rose, Zeitschr. Deutsch. geol. Gesell., vol. 16, 1864, p. 6; E. Svedmark, Neues Jahrb., 1877, p. 99. 3 See discussion of the change by C. H. Gordon, Am. Geologist, vol. 34, 1904, p. 40. METAMORPHIC ROCKS. 591 original igneous rock and the secondary amphibolites there are all possible intermediate gradations, from incipient change to complete transformation . 1 GLAUCOPHANE SCHISTS. The glaucophane schists differ from the amphibolites in that they contain the soda amphibole instead of hornblende. H. S. Wash- ington 2 divides these rocks into three classes, namely, epidote-glau- cophane schist, mica-glaucophane schist, and quartz-glaucophane schist; but he also recognizes the fact that there are many transitional varieties. W. H. Melville , 3 for example, has described a garnet- glaucophane schist from Mount Diablo, California; and A. Wich- mann 4 an epidote-mica-glaucophane schist from Celebes. A zoisite- glaucophane schist from Sulphur Bank, California, is also mentioned by G. F. Becker . 5 It consists chiefly of glaucophane and zoisite, but quartz, albite, sphene, and muscovite are also present. Another rock from Piedmont, containing glaucophane, garnet, hornblende, epidote, mica, and sphene, described by T. G. Bonney , 6 is called a glaucophane eclogite. Genetically, the glaucophane rooks differ widely. Some of them are undoubtedly derived from mediosilicic or subsilicic igneous rocks; others from sedimentaries. In Greece, for example, according to R. Lepsius , 7 some glaucophane schists represent gahbro, and others are metamorphosed Cretaceous shales. The epidote-glaucophane schist of Anglesey, Wales, described by J. F. Blake , 8 was originally a dio- rite, and in this rock alterations of glaucophane to chlorite occur. In Piedmont, as described by S. Franchi , 9 there are glaucophane rocks associated with amphibolite, both having been derived from diabase. In Japan, according to B. Koto , 10 the metamorphosed material was formerly a diabase tuff, and the glaucophane was derived from dial- lage. By further alteration the glaucophane sometimes passes into crocidolite. And on Angel Island, in San Francisco Bay, California, a glaucophane schist studied by F. L. Ransome 11 has been developed 1 On amphibolite produced by the intrusion of granite into limestone, in the Laurentian rocks of Canada, see F. D. Adams, Jour. Geology, vol. 17, 1909, p. 1. 2 Am. Jour. Sci., 4th ser., vol. 11, 1901, p. 35. This memoir is a very complete summary of our knowledge of these rocks. It contains many analyses and abundant references to literature. See also K. Oebbeke, Zeitschr. Deutsch. geol. Gesell., vol. 38, 1886, p. 634; U. Grubenmann, Rosenbusch “ Festschrift, ” 1906; E. H. Nutter and W. B. Barber, Jour. Geology, vol. 10, 1902, p. 738; and J. P. Smith, Proc. Am. Philos. Soc., vol. 45, 1906, p. 183. The last two papers relate to the glaucophane rocks of California. Other note- worthy papers are by E. Murgoci, Bull. Dept. Geology Univ. California, vol. 4, 1906, p. 359; L. Milch, Neues Jahrb., Festband, 1907, p. 348; and T. J. Woyno, Neues Jahrb., Beil Band 33, 1911, p. 136. 3 Bull. Geol. Soc. America, vol. 2, 1890, p. 413. 4 Neues Jahrb., 1893, Band 2, p. 176. 5 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 104. 6 Mineralog. Mag., vol. 7, 1887, p. 1. 7 Geologic von Attika, Berlin, 1893, pp. 102, 133. s Geol. Mag., 1888, p. 125. 9 Bol. Com. geol. ital . , vol. 26, 1895, p. 192. 10 Jour. Coll. Sci. Japan, vol. 1, 1886, p. 85. u Bull. Dept. Geology Univ. California, vol. 1, p. 211. 592 THE DATA OF GEOCHEMISTRY. from a radiolarian chert, probably by contact metamorphism. In many cases the genesis of these rocks is obscure; but Washington sug- gests that the epidote-glaucophane schists represent originally gab- broid magmas, while the quartz-glaucophane schists are metamor- phosed quartzites or quartzose shales. For convenience, differences of origin will be disregarded here and the analyses of this group of rocks are tabulated together, as follows: Analyses of amphibolites and glaucophane schists. a A. Amphibolite dike, Palmer Center, Massachusetts. B. Amphibolite bed, Palmer Center. Analyses A and B by W. F. Hillebrand, Bull. U. S. Geol. Survey No. 228, 1904, p. 36. C. Amphibolite, Crystal Falls district, Michigan. Described by H. L. Smyth, Mon. U. S. Geol. Survey, vol. 36, 1899, p. 397. Analysis by H. N. Stokes. Probably derived from a diabase or basalt. Contains hornblende, plagioclase, biotite, and quartz, with a little rutile and magnetite. D. Epidote-glaucophane schist, Mount Diablo, California. Analysis by W. H. Melville, Bull. Geol. Soc. America, vol. 2, 1890, p. 413. Contains garnets. Possibly derived from shale. E. Garnet-glaucophane schist, Bandon, Oregon. Analyzed and described by H. S. Washington, Am. Jour. Sci., 4th ser., vol. 11, 1901, p. 35. Contains glaucophane, epidote or zoisite, garnet, and white mica. F. Zoisite-glaucophane schist, Sulphur Bank, California. Analysis by Melville. Described by G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, p. 104. G. Mica-glaucophane schist, Island of Syra, Greece. Analyzed and described by Washington, loc. cit* H. Quartz-glaucophane schist, Fourmile Creek, Coos County, Oregon. Analyzed and described by Washington. Contains quartz, glaucophane, chlorite, muscovite, and garnet. A B C D E F G H Si0 2 49. 57 51. 25 50. 36 47. 84 49. 15 49. 68 58. 26 82. 53 ai 2 0 3 14. 23 16. 53 13. 26 16. 88 15. 87 13. 60 16. 21 6. 88 Fe 2 0 3 3. 95 1. 81 6. 30 4. 99 4. 10 1. 86 3. 44 .59 FeO 8. 01 7. 67 9. 34 5.56 7. 58 8. 61 4. 63 4. 11 MgO 6. 14 5. 87 5. 55 7. 89 7. 53 6. 26 4. 99 1. 86 CaO 10. 19 9. 32 7. 85 11. 15 9. 06 10. 97 3. 82 .68 N^O 3. 06 3. 35 2. 11 3. 20 3. 59 3. 09 5. 36 1. 21 k 2 0 .95 .78 1. 14 .46 .54 .12 .39 1.24 h 2 o- . 14 . 19 1. 55 .17 .16 l Q QA .22 .07 h 2 0+ 1. 33 1. 26 1. 55 1. 81 1. 07 > O. cv± .98 1. 35 Ti0 2 2. 03 1. 84 1. 77 1. 19 J 1.31 1. 37 co 2 ... Trace. None. PoO,... . 21 . 31 . 20 . 14 .21 s . . . . 02 (?) VoO,.. . . 04 Undet. Cr 2 0 3 Trace. Trace. NiO Trace. Trace. MnO .27 .28 Trace. .56 Trace. .04 Trace. Trace. SrO.. Trace? (?) BaO. Trace. (?) LioO Trace. Trace? . 100. 14 100. 46 99. 59 100. 65 99. 84 99. 59 99. 67 100. 52 a A number of amphibolites from Massachusetts are described by B. K. Emerson in Mon. U. S. Geol. Sur- vey, vol. 29, 1898. For analyses see also Bull. 419, 1910, pp. 19-21. These amphibolites are regarded as derived from argillaceous limestones. L. Hezner (Min. pet. Mitt., vol. 22, 1903, p. 505) gives several analyses of amphibolites from the Tyrol. See also a table of analyses in Rosenbusch, Elemente der Gesteinslehre, p. 532. See also, on amphibolite, F. Becke, Min. pet. Mitt., vol. 4, 1882, p. 285; and J. A. Ippen, Mitth. Naturwiss. Ver. Steiermark, 1892, p. 328. Ippen describes “normal amphibolite,” and also zoisite, pyrox- ene, feldspar, and garnet amphibolite. METAMORPHIC ROCKS. 593 SERICITIZATION. The conversion of feldspar into muscovite is one of the common- est processes of metamorphism, whether of igneous or of sedimentary rocks. In many instances the mica produced is the compact or fibrous variety known as sericite, which, in former times, was generally mis- taken for talc. The so-called talcose schists of the earlier geologists have proved in most cases to be not talcose,, but sericitic. 1 The iden- tity of sericite with muscovite was finally established by H. Las- peyres 2 in 1880, and since then its occurrence has been repeatedly investigated. The alteration is most conspicuous in regions where the dynamic metamorphism has been most intense — high tempera- ture, the chemical activity of water, and mechanical stress all work- ing together to bring it about. Any feldspathlc rock may undergo sericitization, but orthoclase rocks furnish the most typical exam- ples. The derivation of sericitic schists and gneisses from granite, quartz porphyry, and diabase, and also from arkose and clay slate, has been repeatedly observed. 3 Sericite is commonly derived from orthoclase or microcline, as suggested above, but may be generated from plagioclase feldspars also, the reactions in the two cases being different. In the forma- tion of muscovite from orthoclase the necessary potassium is already present ; but in order to produce muscovite from plagioclase a replace- ment of sodium by extraneous potassium is required. In either case the reaction which takes place may be represented by more than one equation, although it must be admitted that the formulation is purely hypothetical. Until the processes shall have been experimentally reproduced the equations will remain doubtful. First, orthoclase may be transformed to muscovite by the addition of colloidal alumina equivalent in composition to dia spore, thus: KAlSi 3 0 8 + 2A10.0H = KH 2 Al 3 Si 3 0 12 . This reaction is very simple chemically, but geologically improbable. It requires the presence of solutions containing much alumina, and it is not easy to see whence they could be derived. It suggests, how- ever, a possible relation between the formation of sericite and the alteration to bauxite, a possibility which deserves further investi- gation. 1 See G. H. Williams, Bull. U. S. Geol. Survey No. 62, 1890, pp. 60-62, for historical details. 2 Zeitschr. Kryst. Min., vol. 4, 1879, p. 245. 3 See J. G. Lehmann, Untersuchungen iiber die Entstehung der altkrystallinischen Schiefergesteine, Bonn, 1884; A.Wichmann,Verhandl.Naturhist.Ver.preuss.Itheinlandeu. Westfalens, vol. 34, 1877, p. 1; A. von Groddeck, Neues Jahrb., Beil. Band 2, 1883, p. 72; C. Schmidt, idem, Beil. Band 4, 1886, p. 428, and C. Benedicks, Bull. Geol. Inst. Upsala, vol. 7, 1904-5, p. 278. In Jahrb. K. preuss. geol. Landesanstalt, 1885, pt. 1, Von Groddeck describes the derivation of sericite schists from clay slates. 97270°— Bull. 616—16 38 594 THE DATA OF GEOCHEMISTRY. A second, more probable, and even simpler reaction is the following : 3KAlSi 3 0 8 + H 2 0 = KH 2 Al 3 Si 3 0 12 + K 2 Si0 3 + 5Si0 2 . In this case water alone, acting on orthoclase at a high temperature and under pressure, forms muscovite, free silica, and potassium sili- cate, the last compound being leached away. The liberated silica may be partly removed in solution, or it can recrystallize as quartz, a mineral which almost invariably accompanies sericite in meta- morphic rocks. Furthermore, the analyses of sericite usually show a small excess of silica over that contained in normal muscovite. A similar reaction with albite should yield the soda mica paragonite. A modified form of the last reaction is in common use, which in- volves the introduction into the equation of carbonated water, as follows: 3KAlSi 3 0 8 + H 2 0 + C0 2 = KH 2 Al 3 Si 3 0 12 + K 2 C0 3 + 6Si0 2 . In this case, however, the potassium carbonate would dissolve one molecule of the liberated silica, forming potassium silicate as before. The C0 3 would thus be set free again, ready to assist in further alter- ations of feldspar. Since carbonated waters, both of meteoric and of deep-seated origin, are very abundant, it is quite possible that this regenerative process is really in operation. If so, the reaction should be more vigorous than when water acts alone. The frequent association of calcite with sericite is an indication that carbonated solutions have helped to produce the change. 1 If the alteration took place in presence of both albite and orthoclase, the potassium silicate would probably react upon the former mineral or upon its incipient decomposition products, so that muscovite only, without paragonite, would be formed. In the development of muscovite from plagio- clase the presence of potassium-bearing solutions, which exchange alkalies with the sodium compounds, must be assumed. OTHER ALTERATIONS OF FELDSPAR. Apart from the phenomenon of sericitization, the plagioclase feld- spars undergo a number of other metasomatic changes, whose records are preserved in the metamorphic rocks. Under the influence of carbonated waters the anorthite molecule may be decomposed, with the formation of calcite and the separation of silica. In this case the albite remains as a finely granular aggregate, the so-called 11 albite mosaic,” which outwardly resembles quartz and with which quartz is commonly associated. 2 When the lime of the anorthite is not com- 1 Compare W. Lindgren, Trans. Am. Inst. Min. Eng., vol. 30, 1900, p. 608, in reference to the association with calcite. 2 See K. A. Lossen, Jahrb. K. preuss. geol. Landesanstalt, 1884, pp. 525-530. See also G.H. Williams, Bull. U. S. Geol. Survey No. 62, 1890, p. 60. METAMORPHIC ROCKS. 595 pletely removed, it goes to form other silicates, such as epidote, zois- ite, or actinolite. The latter reactions are by far the most frequent. The alteration of plagioclase to zoisite is exceedingly common, but it is rarely complete. As a rule mixtures of zoisite and feldspar remain, which were once thought to represent a distinct mineral spe- cies and to which the name saussurite was given. The mechanism of the change is obscure, but it is probably a double decomposition between the albite and anorthite molecules, brought about by the intervention of water. The feldspars, however, vary in composition; the water may contain other reacting substances in solution, and so the reactions are complicated in many ways. The following equa- tion, which is plausible but not proved, represents the transforma- tion of plagioclase into a mixture of zoisite, paragonite, and quartz, a mixture that sometimes occurs : NaAlSi 3 0 8 + 4CaAl 2 Si 2 0 8 + 2H 2 0 = Albite. Anorthite. Water. 2Ca 2 HAl 3 Si 3 0 13 + H 2 NaAl 3 Si 3 0 12 + 2Si0 2 . Zoisite. Paragonite. Quartz. When orthoclase molecules are present, muscovite will be formed; that is, sericitization and saussuritization may go on together. With albite in excess, the saussurite mixture appears, but that again is variable. It may contain epidote, scapolite, or garnet; according to A. Cathrein, 1 saussurite is sometimes derived from garnet; and all of these minerals may undergo complete or partial alterations into other compounds. Saussuritic rocks have been described by many petrographers, and there is abundant literature covering them. F. Becke 2 reports a saussurite gabbro from Greece, consisting of saussurite and dial- lage, the latter partly altered to hornblende. P. Michael 3 describes another saussurite gabbro from Germany, in which garnet is also present, derived from diallage and partly altered to serpentine. Another saussurite gabbro from Sturgeon Falls, Michigan, was care- fully studied by G. H. Williams. 4 It contained saussurite derived from the complete alteration of plagioclase, diallage, hornblende partly secondary, and a little ilmenite, with some calcite, quartz, and a colorless chlorite. By further alteration this rock passes into a silvery schist, consisting mainly of chlorite, calcite, and secondary quartz, but with some feldspars remaining, partly sericitized. A rock designated as a zoisite-hornblende diorite, from the Bradshaw Mountains, Arizona, described by T. A. Jaggar and C. Palache, 5 6 1 Zeitschr. Kryst. Min., vol. 10, 1885, p. 444. 2 Min. pet. Mitt., vol. 1, 1878, p. 247. 3 Neues Jahrb., 1881, Band 1, p. 32. 4 Bull. U. S. Geol. Survey No. 62, 1890, pp. 67-76. Another saussuritized gabbro from the Upper Quinnesec Falls is described on pp. 102-104. On pp. 58-60 Williams gives a general discussion of this form of alteration, with historical details. See also A. Cathrein, Zeitschr. Kryst. Min., vol. 7, 1883, p. 234. 6 Bradshaw Mountains folio (No. 126), Geol. Atlas U. S., U. S. Geol. Survey, 1905, pp. 4-5. 596 THE DATA OF GEOCHEMISTRY. contained 47 per cent of zoisite, derived from plagioclase, 17 per cent of actinolite, and smaller amounts of quartz, orthoclase, albite, chlorite, kaolin, and magnetite. The following analyses of zoisite rocks were made in the laboratory of the United States Geological Survey : Analyses of zoisite rochs. A. Sturgeon Falls gabbro, freshest form. B. The same, altered form. C. Silvery schist derived from Sturgeon Falls gabbro. Analyses A, B, and C by B. B. Riggs. D. Zoisite-hornblende diorite, Bradshaw Mountains. Analysis by George Steiger. A B C D Si0 2 51. 46 38. 05 45. 70 45. 73 ALOo 14. 35 24. 73 16.53 19. 45 Fe,0, 3. 90 5. 65 4. 63 5. 28 FeO 5. 28 6. 08 3.89 3. 18 9. 54 11. 58 9. 57 6. 24 CaO 9. 08 1. 25 4. 28 13. 86 Na 2 0 2. 92 2. 54 .55 .64 K 2 0 .24 1. 94 } 7.53 3.82 .32 H 2 0- 1. 57 h 2 o+ } 3.30 j 4. 70 3. 56 Ti0 2 ) J J .23 co 2 .20 .93 5. 95 .28 p 9 o, Trace. A 2 W 5 100. 27 100. 28 99. 62 100. 34 The sericitization of C is shown by the loss of sodium and great increase of potassium. The Sturgeon Falls series is especially in- structive as illustrating the occurrence of several alterations, partly simultaneous and partly successive, in the same rock formation. Saussurite, sericite, and uralite are all represented. The transformation of plagioclase into scapolite is by no means rare, but the nature of the process is not always easy to trace. Scap- olite is often formed by contact reactions between igneous rocks and limestones, as, well as by processes resembling that of saussuritiza- tion. For the latter change, which is the one to be properly con- sidered now, the classical example is furnished by the spotted gabbro of Oedegaarden. In this case a plagioclase-pyroxene rock has been altered into a scapolite-hornblende mixture, a rock which, according to Fouque and Levy, 1 is retransformed on fusion into pyroxene and labradorite. The alteration, then, is reversible and one which ought to be studied quantitatively. The change from plagioclase to scapo- lite, as investigated by J. W. Judd, 2 is probably due to the action of 1 Bull. Soc. min. , vol. 2, 1879, p. 113. 2 Mineralog. Mag., vol. 8, 1889, p. 186. See also A. Michel-Lgvy, Bull. Soc. min., vol. 1, 1878, pp. 43, 78. A similar rock from Bamle, Norway, containing sphene, amphibole, and wernerite, is also described. Other noteworthy memoirs on the Scandinavian rocks of this class are by A. E. Tomebohm and E. Svedmark, Geol. Foren. Forhandl., vol. 6, 1882, p. 192; vol. 7, 1884, p. 293. METAMORPHIC ROCKS. 597 sodium chloride, which exists in solution in minute inclusions within the original rock. It must be noted, however, that the Oedegaarden gabbro is in contact with veins of chlorapatite, from which some of the chlorine essential to the formation of scapolite may have been derived. In any case, the conversion of plagioclase to scapolite requires the addition of new material. The scapolites, as shown by G. Tscher- mak, 1 are mixtures of two end species — meionite, Ca 4 Al 6 Si 6 0 25 , and marialite, Na 4 Al 3 Si 9 0 24 Cl. These may be derived from anorthite and albite in accordance with the following empirical equations : 3CaAl 2 Si 2 0 8 + CaO = Ca 4 Al 6 Si 6 0 25 . 3NaAlSi 3 0 8 + NaCl = Na 4 Al 3 Si 9 0 24 Cl. In order to change an ordinary plagioclase into an ordinary scapo- lite, then, lime and sodium chloride must be taken up, and it is clear that these reagents may come from quite dissimilar sources. The change of pyroxene to amphibole may furnish the lime in some cases; apatite may yield it, with chlorine, in others; but no general rule, no exclusive group of reactions, can be postulated. The widely different conditions under which scapolitization may take place have been well summarized by A. Lacroix, 2 whose two memoirs upon the subject are most exhaustive. On the epidotization of plagioclase feldspar there is an abundant literature. 3 Since epidote and zoisite are closely analogous in chem- ical structure, the process of alteration must resemble that of saus- suritization, from which it differs in detail. Epidote contains iron, typical zoisite does not; and that element seems commonly to be furnished by hornblende or pyroxene. Feldspar, augite, hornblende, and biotite all alter into epidote ; and so, too, in some cases apparently does chlorite. The derivation of epidote from chlorite has been observed by G. F. Becker 4 in the rocks of the Comstock lode, and although the observation is questioned by some authorities, it is 1 See the section on scapolite in Chapter X, p. 404, ante. 2 Bull. Soc. min., vol. 12, 1889, p. 83; vol. 14, 1891, p. 16. Lacroix states that wernerite gneisses are very common. Lacroix and C. Baret (idem, vol. 10, 1887, p. 288) describe a wernerite pyroxenite. Wernerite, it will he remembered, is one of the intermediate scapolites. See also H. Wulf, Min. pet. Mitt., vol. 8, 1887, p. 213, on a scapolite-augite gneiss from Herero Land, Africa; and F. Becke, idem, vol. 4, 1882, p. 285, on similar rocks from Lower Austria. Scapolite amphibolites are described by O. Miigge, Neues Jahrb., Beil. Band 4, 1886, p. 583, from Masai Land; E. Dathe, Jahrb. K. preuss. geol. Landesanstalt, 1884, p. lxxvi, from Germany; and F. D. Adams and A. C. Lawson, Canadian Rec. Sci., vol. 3, 1888, p. 185, from Canada. .Adams and Lawson also describe two scapolite diorites. The scapolite rocks of northern New Jersey, briefly described by F. L. Nason (Ann. Rept. State Geologist, 1890, p. 33), occur as dikes in crystalline limestone, and may have been formed by contact metamorphism. C. H. Smyth (Am. Jour. Sci., 4th ser., vol. 1, 1896, p. 273), has described the transformation of a gabbro into a gneiss containing pyroxene, horn- blende, feldspar, and scapolite. 2 See A. Cathrein, Zeitschr. Kryst. Min., vol. 7, 1883, p. 247; A. Schenck, Verhandl. Naturhist. Ver. preuss. Rheinlande u. Westfalens, vol. 41, 1884, p. 53; and G. H. Williams, Bull. U. S. Geol. Survey No. 62, 1890, p. 56, for summaries of the earlier observations. * Mon. U. S. Geol. Survey, vol. 3, 1882, pp. 75, 76, 213. Criticised by Williams, loc. cit., and H. Rosen- busch, Neues Jahrb., 1884, Band 2, Ref., p. 189. 598 THE DATA OF GEOCHEMISTRY. not disproved. Chemically, it is not improbable; but usually the two minerals, chlorite and epidote, form simultaneously from a common parent. In the rocks of Leadville, W. Cross 1 found epidote derived from ortboclase, plagioclase, biotite, and hornblende. G. H. Wil- liams 2 observed its formation as a contact rim between feldspar and hornblende in the gabbro-diorite near Baltimore, and F. D. Chester 3 described similar occurrences in Delaware. In some of Chester’s specimens the epidote contained cores of feldspar. Epidotization, then, represents a reaction between the feldspars and the ferromagnesian minerals of a rock, and when it is complete a mixture of quartz and epidote remains. Such a rock is known as epidosite, and its formation has been many times recorded. J. Lem- berg 4 describes an alteration of this kind from augite porphyry ; and Schenck 5 reports the derivation of epidosite from diabase. Unakite is a remarkable rock consisting of rose-colored orthoclase and green epidote, first described by F. H. Bradley 6 from western North Carolina. It has since been found near Milams Gap, Virginia. According to W. C. Phalen , 7 who has studied this locality, the una- kite is derived from a hypersthene akerite, or quartz-diallage syenite, and it contains, in addition to the two principal minerals, some quartz, iron oxides, zircon, and apatite. It passes into epidosite by further alteration. Epidote-quartz rocks from New Jersey have also been briefly described by L. G. Westgate . 8 9 Here, as at Milams Gap, the epidote is thought to be derived from pyroxene. Garnet is a common mineral of the metamorphic rocks, and is often indicated in their nomenclature. Garnet gneiss, garnet-mica schist, garnet homfels, and garnet-olivine rock are good examples. In these rocks, however, garnet is commonly an accessory mineral rather than a main constituent. On the other hand, rocks are known con- sisting chiefly or largely of garnet, and one of these, eclogite, has been the subject of many investigations . 8 Eclogite is essentially a rock composed of red garnet, with a green pyroxene, omphacite. It may also contain, subordinately, horn- blende, quartz, zoisite, kyanite, and muscovite, with zircon, apatite, sphene, epidote, magnetite, pyrite, and pyrrhotite as minor acces- sories . 10 According to J. A. Ippen , 11 the Styrian eclogites shade into 1 Mon. U. S. Geol. Survey, vol. 12, 1886, pp. 341, 357. 2 Bull. U. Si Geol. Survey No. 28, 1886, p. 31. a Bull. U. S. Geol. Survey No. 59, 1890, p. 35. 4 Zeitschr. Deutsch. geol. Gesell., vol. 29, 1877, p. 498. 6 Verhandl. Naturhist. Ver. preuss. Rheinlande u. Westfalens, vol. 41, 1884, p. 53. 6 Am. Jour. Sci., 3d ser., vol. 7, 1874, p. 519. 7 Misc. Coll. Smithsonian Inst., Quart. Issue, vol. 1, 1904, p. 301. 8 Ann. Rept. State Geologist New Jersey, 1895, p. 30. 9 See Zirkel’s Lehrbuch der Petrographie, 2d ed., vol. 3, p. 369, for many references. The papers by Lohmann and Hezner, cited on the next page, also contain bibliographies. 10 See R. von Drasche, Jahrb. K.-k. geol. Reichsanstalt, 1871, Min. Mitt.,p. 85, and E. R. Riess, Min. pet. Mitt., vol. 1, 1878, pp. 165, 181. 11 Mitt. Naturwiss. Ver. Steiermark, 1892, p. 328. METAMORPHIC KOCKS. 599 omphacite rock on one side and into garnet rock on the other; that is, either mineral may predominate and give its own character to the mixture. The eclogites of the lower Loire, according to A. Lacroix , 1 sometimes contain feldspar formed as a secondary mineral during the uralitization of highly aluminous pyroxenes. Lacroix shows that these rocks are products of dynamometamorphism. The crushing and fracturing of the original rocks has facilitated the cir- culation of the waters to which their alterations are due. L. Hezner , 2 who studied eclogite from the Oetzthal, in the Tyrolese Alps, regards it as a metamorphic derivative of gabbroid rocks. By further metamorphosis it passes into amphibolite, the eclogite being the deeper-seated phase. The garnet, he thinks, was formed by a reaction between plagioclase and olivine, or perhaps between plagio- clase and pyroxene. The omphacite alters into hornblende, and so, too, does the garnet, but later. First eclogite, then garnet amphib- olite, then amphibolite, is the order of these allied rocks. Plagio- clase also appears, as observed by Lacroix, among the products of alteration, together with epidote, chlorite, magnetite, zoisite, and biotite. The following analyses of epidote and garnet rocks are from the memoirs already cited: Analyses of epidote and garnet rochs. A, B. Epidosite derived from diabase, upper Ruhrthal, Germany. Analyzed and described by Schenck. C. Unakite, Milam’s Gap, Virginia. Analysis by Phalen. D. Eclogite, Sulzthal, Styria. E. Eclogite, Burgstein, Styria. Analyses D and E by Hezner. A B C D E SiO 42. 13 50. 26 58. 32 44. 06 46. 26 A1 2 0 3 19.21 13. 72 15. 77 17. 63 14. 45 Fe 2 0 3 11. 19 9. 18 6. 56 3.40 4. 41 FeO 2. 52 2. 97 .89 9. 96 5. 82 MgO .41 2. 20 . r 9 7. 19 11. 99 CaO 21. 42 16. 30 11. 68 11.58 11. 66 Na 2 0 .29 .71 .32 2. 92 2. 45 K 2 0 .08 1. 12 4. 01 .91 1. 51 H 2 0- 'j . 12 h 2 0+ > 2. 39 f 1.88 f 1. 73 .17 1. 10 Ti0 2 1. 40 1. 60 (a) 2. 29 .28 Zr0 2 Trace. PXL .08 .39 .48 MnO .13 FeS 2 .25 .26 101. 37 100. 59 99. 98 100. 23 99. 93 « Not separated from alumina. 1 Bull. Soc. sci. nat. de l’Ouest de la France, vol. 1, 1891, p. 81. 2 Min. pet. Mitt., vol. 22, 1903, pp. 437, 505. See also E. Joukowsky, Compt. Rend., vol. 133, 1901, p. 1312, on alterations of eclogite from Lac Cornu. Other valuable papers upon eclogite are by P. Lohmann, N eues Jahrb., 1884, Band l,p. 83; and F. Becke, Min.pet.Mitt.,vol.4,1882, pp. 317-322. Eclogites from California have been described by R. S. Holway, Jour. Geology, vol. 12, 1904, p. 344, and J. P. Smith, Proc. Am. Philos. Soc., vol. 45, 1906, p. 183. 600 THE DATA OF GEOCHEMISTRY. CHLORITIZATION. In chloritization we find a stage of metamorphism which is nearly akin to decomposition. Any ferromagnesian mineral may alter into chloritic material, and that, by further change, may break down into a mixture of carbonates, limonite, and quartz. The gabbros of Michi- gan, described by G. H. Williams , 1 show clearly the successive steps of uralitization and chloritization, the final product often being a chloritic schist. Diabase and diorite are often chloritized, gaining thereby the green color to which the common appellation “ green- stone’’ is due. In diabase the chloritic substance is commonly derived from augite, calcite and quartz being formed at the same time. The alumina needed to produce the chlorite is probably furnished by feldspar . 2 Under anhydrous conditions, as we have already seen, a reaction between feldspars and ferromagnesian minerals yields garnet; possibly the formation of chlorite is similar, but effected in presence of water. The alterability of garnet into chlorite empha- sizes this suggestion. The chlorites developed in rocks of igneous origin are rarely definite species. They are, as a rule, variable mixtures, of which many have received specific names. Diabantite and prochlorite, both ferrifer- ous, are perhaps the most common. Because of this vagueness, Rosenbusch prefers to use the collective term “chloritic substance” in describing the products of this class. The general names “viri- dite” and “chloropite” have also been proposed; the one by H. Vogelsang, the other by C. W. Giimbel. CONSTITUTIONAL FORMULAE. Although it is not yet possible to write positive reactions for all of the alterations that we have so far been considering, some of them are partly elucidated by the structural formulae of several minerals. A number of these species are curiously alike in constitution, and with them other minerals, not specifically studied in this chapter, may also be compared. Taking the tripled formulae of orthoclase and albite, which are suggested by the alteration of albite into marialite, the following system of formulae can be developed : 3 Orthoclase Al 3 (Si 3 0 8 ) 3 K 3 . Albite Al 3 (Si 3 0 8 ) 3 Na3. Marialite Al 2 ( Si 3 0 8 ) 3 N a 4 ( A1C1) . Nephelite Al 3 (Si0 4 ) 3 Na 3 . Paragonite Al 3 (Si0 4 ) 3 NaH 2 . Muscovite Al 3 (Si0 4 ) 3 KH 2 . 1 Bull. U. S. Geol. Survey No. 62, 1890. 2 See G. W. Hawes, Am. Jour. Sci./3d ser., vol. 9, 1875, pp. 190, 454. Also A. Schenck, Verhandl. Natur- hist. Ver. preuss. Rheinlande u. Westfalens, vol. 41, 1884, p. 74. Chloritization is fully discussed by Rosen- busch in his Mikroskopische Physiographic der massigen Gesteine, 2d ed., vol. 2, pp. 180-184. « See F. W. Clarke, Bull. U. S. Geol. Survey No. 588, 1914, for an extended discussion of these formulae. METAMORPHIC ROCKS. 601 Topaz Al 3 (Si0 4 ) 3 (AlF 2 )3. Andalusite Al 3 (Si0 4 ) 3 (A10) 3 . Biotite A1 2 (S i0 4 ) 3 Mg 2 KH . Garnet Al 2 (Si0 4 ) 3 Ca 3 . Prehnite Al 2 (Si0 4 ) 3 Ca 2 H 2 . Zoisite Al 2 (Si0 4 ) 3 Ca 2 (A10H) . Epidote resembles zoisite, but with iron partly replacing aluminum, and similar replacements occur in the garnet group. These formulae, however, are neither absolute nor final. They represent definite relations, and also the minimum molecular weights assignable to the several minerals, the true molecular weights being unknown and at present undeterminable. It is probable that some of the formulae should be doubled, and when that is done some strik- ing new relations appear. This is shown in the following group of structural expressions : .Si0 4 =Al 2 =Si0 4 x Al— Si0 4 =Al 2 =Si0 4 — A1 \si0 4 EsCa=Si0/ Anorthite. /Si0 4 =Ca 3 =Si0 4 x Al— Si0 4 =Ca 3 =Si0 4 — Al \si0 4 =Ca=SiO/ / Gehlenite. 1 / Si0 4 =Ca 3 =Si0 4 v Al— Si0 4 =Ca 3 =Si0 4 — Al \si0 4 — Ca— Sio/ AlOH AlOH Vesuvianite. / Si0 4 =Al 2 =Si0 4 v Al— Si0 4 =Ca=Si0 4 — Al \si0 4 =Ca 3 =Si0 4 / Garnet. xSi0 4 =Al 2 =Si0 4 x Al— Si0 4 =Ca 3 =Si0 4 — Al \siO— Ca— Sio/ II II AlOH AlOH Zoisite. ✓Si0 4 =Al 2 =Si0 4 x Al— Si0 4 =Al 2 =Si0 4 — Al \si0 4 =Ca 2 =Si0 4 / I I Ca O Ca Meionite. In the first group of formulae the fundamental nucleus, which occurs in all of them, 2 is Al(Si0 4 ) 3 . In the second group it is Al 2 (Si0 4 ) 6 , or double the other. The two sets are identical in type, and with their aid the observed alterations become intelligible. One species changes into another by replacements of atoms, the typical structures — the nuclei, so to speak — remaining undisturbed. When the trisilicate feldspars alter into orthosilicates, silica is liberated; but the other changes are simpler. For example, nephelite, topaz, and andalusite all change easily into muscovite; members of the garnet group can form epidote, biotite, or the normal chlorites, and so on. Pyroxenes 1 More properly the principal constituent of the mixed crystals known as gehlenite. * Except the trisilicate feldspars in which the group SisOs is equivalent to SiO<. 602 THE DATA OF GEOCHEMISTRY. and amphiboles, however, are compounds of different structure from those given in the foregoing table, and the mechanism of their alter- ations is not so clear. Some of the phenomena are easily understood; others still await interpretation. It is possible to write empirical equations in all cases, but they have slender value. A correlation between molecular constitution and the observed changes must be established before the chemistry of metamorphism can be completely described. TALC AND SERPENTINE. When distinctively magnesian silicates undergo hydrous meta- morphism, which happens chiefly in the belt of weathering, the product is likely to be either talc or serpentine. 1 Other hydrous sili- cates may be formed also, together with carbonates and the hydrox- ide, brucite; but the two species just named are the most important. I speak now, of course, with reference to alterations in place; such a rock as dolomite falls in quite another category. A typical production of serpentine is from rocks containing olivine; and the probable reaction is as follows: 2Mg 2 Si0 4 + 2H 2 0 + C0 2 = Mg 3 H 4 Si 2 0 9 + MgC0 3 . Olivine. Serpentine. Magnesite. Peridotites are especially liable to this sort of alteration, and many serpentine rocks can be assigned this origin. 2 The well-known Lizard serpentine of Cornwall, for instance, has been shown by T. G. Bonney 3 to be an altered Iherzolite. Pyroxenes, also, are often converted into serpentine. The equa- tion, in the case of diopside, is perhaps as follows: 3MgCaSi 2 0 6 + 3C0 2 + 2H 2 0 = Mg 3 H 4 Si 2 0 9 + 3CaC0 3 + 4Si0 2 . Diopside. Serpentine. Calcite. Quartz. This reaction is sustained by the fact that serpentine rocks often contain quartz and calcite. When serpentine is formed from gabbro or pyroxenite the change is probably of this kind, although it may have been preceded by uralitization of the pyroxene. Serpentines derived from amphibolites have been repeatedly described. 4 1 According to G. P. Merrill (Geol. Mag., 1899, p. 354) the formation of serpentine as a rock is a deep-seated process. This conception, however, does not preclude the generation of disseminated serpentine, regarded not as a rock but as a mineral species, within the belt of weathering. 2 See F. Sandberger, Neues Jahrb., 1866, p. 385; idem, 1867, p. 176; G. Tschermak, Sitzungsb. K. Akad. Wiss. Wien, vol. 56, 1867, p. 261; E. Weinschenk, Abhandl. K. bayer. Akad., Math.-phys. Klasse, vol. 18, p. 651; J. Lemberg, Zeitschr. Deutsch. geol. Gesell., vol. 27, 1875, p. 531; B. Weigand, Jahrb. K.-k. geol. Reichsanstalt, 1875, Min. Mitt., p. 183. F. Zirkel (Lehrbuch der Petrographie, 2d ed., vol. 3, p. 404) gives an extensive bibliography of serpentine. 3 Quart. Jour. Geol. Soc., vol. 33, 1877, p. 884. * B. K. Emerson (Mon. U. S. Geol. Survey, vol. 29, 1898, p. 114) assigns this origin to the serpentines of the Connecticut Valley. An Australian amphibolite serpentine has also been described by J. B. Jaquet, Rec. Geol. Survey New South Wales, vol. 5, 1896-1898, p. 21. METAMORPHIC ROCKS. 603 In short, serpentine may be formed from any silicate which hap- pens to be rich in magnesia, such as olivine, pyroxene, amphibole, garnet, 1 or chondrodite. 2 It also appears to be produced by the action of percolating magnesian waters upon nonmagnesian minerals, such as feldspars, and possibly, even, quartz. 3 J. Lemberg 4 has shown that solutions of magnesium carbonate will attack oligoclase, replacing sodium by magnesium to a considerable extent; but alter- ations of this sort are not very common. Many reported changes of minerals to talc or serpentine have been erroneous, for compact mus- covite is easily mistaken for them. A pseudomorphous mineral should be called serpentine or steatite only after thorough chemical and optical examination. The mere fact that a mineral is green, soft, compact, and soapy to the touch is not enough to establish its character. In many localities serpentine is associated with dolomite or dolo- mitic limestone. In these cases the mineral has been derived from magnesian silicates, which were first formed within the limestone by metamorphic processes. In the limestones of Westchester County, New York, according to J. D. Dana, 5 the parent minerals were tremo- lite or actinolite. It is possible also that some dolomite itself may have become silicated, yielding serpentine by alteration of the com- pounds thus formed. Similar views are advanced by S. F. Emmons 6 with reference to serpentines found near Leadville, Colorado. The serpentine of Montville, New Jersey, which is also in dolomite, was shown by G. P. Merrill 7 to be derived from pyroxene, and the same conclusion was reached regarding the ophiolite or ophicalcite of Warren County, New York. 8 The “verde-antique” marbles are familiar illustrations of this commingling of carbonates with serpen- tine. A quite different blending of serpentine with other minerals is that described by me from Stephens County, W ashington. 9 This mix- ture was apparently a normal serpentine; but upon analysis it was found to contain only 20 per cent of that species, with 60 per cent of brucite, 14 per cent of chlorite, and 5 per cent of hydromagnesite. Its origin, so far as I am aware, has not been determined. In the quicksilver region of California G. F. Becker 10 found ser- pentines which had been decomposed by solfataric agencies until only the silica remained. Similar reductions of serpentine to opal, 1 See A. Schrauf, Zeitschr. Kryst. Min., vol. 6, 1882, p. 321. 2 See J. D. Dana, Am. Jour. Sci., 3d ser., vol. 8, 1874, p. 371, on serpentine pseudomorphs from the Tilly Foster mine. 3 See G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, pp. 108-128. 4 Zeitschr. Deutsch. geol. Gesell., vol. 22, 1870, p. 345; vol. 24, 1872, p. 255. 6 Am. Jour. Sci., 3d ser., vol. 20, 1880, p. 30. 6 Mon. U. S. Geol. Survey, vol. 12, 1886, p. 282. 7 Proc. U. S. Nat. Mus., vol. 11, 1888, p. 105. 8 Am. Jour. Sci., 3d ser., vol. 20, 1880, p. 30. 9 Bull. U. S. Geol. Survey No. 262, 1905, p. 69. 10 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 127. 604 THE DATA OF GEOCHEMISTRY. chalcedony, and quartz have been recorded by A. Lacroix. 1 The acids of volcanic fumaroles bad removed the bases of the serpentine in the form of soluble sulphates. From what has been said so far it is evident that serpentine origi- nates in various different ways. Some serpentine is merely altered peridotite, pyroxenite, or gabbro; and some of it is derived from dolomite or other sedimentary rocks. Indeed, the sedimentary origin of serpentine has bad many strong advocates, the chief among them having been the late T. Sterry Hunt. 2 L. Dieulafait 3 also has argued that the serpentines of Corsica are true sedimentary rocks. There is 7 in fact, no valid reason why siliceous magnesian sediments, precipi- tated or detrital, should not form beds of serpentine; but the rock is commonly a metamorphosed eruptive, or else the result of a sec- ondary metamorphism of sibceous limestones. In both of these gen- erally recognized modes of formation the chemical processes are the same. The same magnesian silicates are altered in the same way irrespective of their igneous, metamorpbic, or sedimentary origin. Serpentine is a basic ortbosilicate, talc an acid metasihcate. The former alters easily, and is readily decomposed; the latter is one of the least alterable and therefore among the most stable, under aqueous conditions, of mineral species. Both minerals are decom- posed by beat, but differently. Serpentine breaks up into enstatite and olivine; talc into enstatite or antbopbyllite and quartz, water being eliminated in both cases. These decompositions may be written thus: Mg 3 H 4 Si 2 0 9 = Mg 2 Si0 4 + MgSiO a + 2H 2 0. Mg 3 H 2 Si 4 0 12 = 3MgSi0 3 + Si0 2 + H 2 0. Talc, bke serpentine, may originate in different ways; but its com- monest derivation seems to be by the alteration of amphiboles or pyroxenes. C. H. Smyth, 4 who studied the talc of St. Lawrence County, New York, found it to be derived in that region from enstatite and tremobte, accordmg to the following reactions: 4MgSi0 3 + H 2 0 + C0 2 = Mg 3 H 2 Si 4 0 12 + MgC0 3 . MggCaSqO^ + H 2 0 + C0 2 = Mg 3 H 2 Si 4 0 12 + CaC0 3 . These reactions are much alike, and resemble those which are recog- nized in the formation of serpentine. In fact, many serpentines contain admixtures of talc, and when the original rocks are at all 1 Compt. Rend., vol. 124, 1887, p. 513. 2 Mineral physiology and physiography, 1886, pp. 434-516. Hunt cites a large amount of evidence from Italian sources. 3 Compt. Rend., vol. 91, 1880, p. 1000. 4 School of Mines Quart., vol. 17, 1896, p. 333. METAMORPHIC ROCKS. 605 aluminous, chlorites also may appear. Soapstone or steatite is impure, massive talc. According to Smyth, the St. Lawrence County talc is found asso- ciated with crystalline limestones. J. H. Pratt 1 found the deposits of North Carolina to be in connection with marble, and capped by quartzite. In the same region pyrophyllite occurs, a hydrous sili- cate of aluminum, HAlSi 2 0 6 , which much resembles talc and may be mistaken for it. The talc itself appeared to be derived from tremolite. Smyth assumes that a siliceous limestone was first laid down, which became, by metamorphism, a tremolite-enstatite schist. The latter, by hydration, became talc. This, however, is not the only way in which steatite has been formed. A. Gurlt 2 reports its formation from dolomite along contacts with amphibolite; and C. H. Hitchcock 3 regards the steatites of New Hampshire as alterations of what was originally igneous matter. The talc of Mautern in Styria is traced by K. A. Kedlich and F. Cornu 4 to the action of magnesian solutions upon the surrounding schists. Pseudomorphs of talc after many minerals have been described, but not all of the reports are authentic. The warning given under serpentine may well be recalled here. Pseudomorphs of talc after quartz, however, seem to be well known. 5 Much work needs to be done in order to deter- mine the origin of soapstone generally. The following analyses represent talcose and serpentinous rocks of varied characters. 1 North Carolina Geol. Survey, Econ. Paper No. 3, 1900. 2 Sitzungsb. Niederrhein. Gesell. Natur u. Heilkunde, Bonn, 1865, p. 126. s Jour. Geology, vol. 4, 1896, p. 58. ?Zeitschr. prakt. Geologie, 1908, p. 145. ®E. Weinschenk, Zeitschr. Kryst. Min., vol. 14, 1888, p. 305. 606 THE DATA OF GEOCHEMISTRY. Analyses of talcose and serpentinous rocks. A. Dark-green serpentine, Rowe, Massachusetts. Described by B. K. Emerson in Mon. U. S. Geol. Survey, vol. 29, 1898. Analysis by G. Steiger. B . Serpentine, Greenville, California. Described by J. S. Diller in Bull. U. S. Geol. Survey No. 150, 1898, p. 372. Derived mainly from pyroxene. Analysis by W. H. Melville. C. Serpentine, Sulphur Bank, California. Described by G. F. Becker in Mon. U. S. Geol. Survey, vol. 13, 1888. Analysis by Melville. D . Serpentine derived from pyroxenite, Mount Diablo, California. Analyzed and described by Melville, Bull. Geol. Soc. America, vol. 2, 1890, p. 403. E. Serpentinous rock of unusual composition; also from Mount Diablo. Analyzed and described by Melville, loc. cit. F. “Ovenstone” from Canton Valais, Switzerland. Described by T. G. Bonney (Geol. Mag., 1897, p. 110) as a stage in the alteration of serpentine. The original rock was perhaps a basalt or dolerite. Analysis by Emily Aston. G. Brucite serpentine, Stevens County, Washington. Described by F. W. Clarke, Bull. U. S. Geol. Survey No. 262, 1905, p. 69. Analysis by G. Steiger. H. Steatite, Griqualand West, South Africa. Described by E. Cohen, Neues Jahrb., 1887, Band l,p. 119. Analysis by Van Riesen. A B c D E F G H Si0 2 40. 42 39. 14 41.86 40. 50 30. 98 44. 94 13.08 63. 29 A1 2 0 3 1. 86 2. 08 .09 . 78 1. 04 5. 47 1. 63 1. 24 Fe 2 0 3 2. 75 4. 27 4. 01 4. 01 4. 88 1. 75 1. 25 FeO 4. 27 2. 04 4. 15 2.04 2. 01 3.47 . 19 4. 68 MgO 35. 95 39. 84 38. 63 37. 43 38. 44 25. 57 56. 44 27. 13 CaO . 66 Trace. .39 .22 8. 76 .33 Trace. Na 2 0 } - 16 .28 .40 None. K 2 0 .16 .16 None. H 2 0- .21 }l2. 70 }l4. 16 ) 2. 81 .39 .35 .85 } 4.40 ) H 2 0+ 10. 51 10. 94 20. 43 5. 40 23. 94 Ti0 2 None. J C0 2 : 1. 44 1. 22 2. 03 P 9 0, Trace. Trace. Trace. Cr 2 0 3 .28 .24 .41 .34 Trace. NiO .53 Trace. .11 2. 90 CoO Trace. MnO Trace. .20 .13 .42 Trace. S0 3 Trace. .44 FeS 2 .43 Chromite .11 99. 47 100. 18 99. 93 99. 99 100. 15 99. 83 99. 74 100. 00 The presence of chromium and nickel in several of these rocks is a good indication of a relationship with the pyroxenite and perido- tites. Chromite and nickel ores are very generally associated with these magnesian eruptives. QUARTZITE. The processes which operate in the metamorphism of sedimentary rocks are partly identical with those which we have just been consid- ering. This fact has already been indicated in several connections. A shale, or sandstone, contains fragments of minerals, usually more or less weathered, and these undergo the normal changes. Feldspar becomes sericite, hornblende alters to chlorite, and so on, exactly as in the metamorphoses of igneous material. The substances affected METAMORPHIC ROCKS. 607 are the same, and so are the reactions. The formation of serpentine from pyroxene, for example, is, as I have already said, the same process, whether it is effected upon the pyroxene of a gabbro or upon the pyroxene developed by contact metamorphism in a crystalline limestone. There is, however, another set of changes which are peculiar to the sedimentaries. These rocks contain decomposition products, such as kaolinite, hydroxides of aluminum and iron, etc., which give rise to a different group of reactions, and these generate another class of min- eral species. Kyanite, andalusite, sillimanite, staurolite, and dumor- tierite are among the minerals thus developed in schists which once were shales. These minerals, again, can alter into mica, so that a mica schist may represent the outcome of a series of transformations, the intermediate products having disappeared. Just as the sedimentary rocks shade into one another, so, too, do their metamorphic derivatives, but with even greater complexity. For the metamorphosed rocks contain not only the original minerals of the sediments, but also the new products formed by alteration. Perhaps the simplest of these changes is that of a sandstone into a quartzite, which, in the first instance, is brought about by infiltration of silica. In this way the interstices of the sandstone are filled up and a porous rock is transformed into a compact one. But as sand- stones are not all sand, so quartzites are not all silica. A micaceous sandstone yields a micaceous quartzite; a feldspathic sandstone may form either an arkose gneiss, or by sericitization it can become a mica schist; and between these different rocks there are all manner of gradations. These changes, moreover, are often complicated by structural modifications due to dynamic agencies; so that from sim- ilar sandstones very different rocks can be derived. In some cases the nature and order of the changes can be traced; in others they seem to be hopelessly obscure . 1 The following analyses of quartzite and quartz schist are useful for comparison with the analyses of sandstones given in the preceding chapter: 1 For a full discussion relative to the formation of quartzite, see C. R. Van Hise, A treatise on metamor- phism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 865-880. See also R. D. Irving, Bull. U. S. Geol. Survey No. 8, 1884, p. 48; Am. Jour. Sci., 3d ser., vol. 25, 1883, p. 401. Important papers on the subject have been written by C. Lossen, Zeitschr. Deutsch. geol. Gesell., vol. 19, 1867, p. 615, and W. J. Sollas, Sci. Proc. Roy. Dublin Soc., vol. 7, 1892, p. 169. 608 THE DATA OF GEOCHEMISTRY. Analyses of quartzite and quartz schist. A. Dark vitreous quartzite, Pigeon Point, Minnesota. Contains quartz, with a little feldspar, chlorite, mica, and magnetite. Described by W. S. Bayley, Bull. U. S. Geol. Survey No. 109, 1893. Analysis by R. B. Riggs. B. Red vitreous quartzite, Pigeon Point. Bayley and Riggs as above. C. Quartzite, South Mountain, Pennsylvania. Described by F. Bascom, Bull. U. S. Geol. Survey No. 136, 1896. Analysis by F. A. Genth, on p. 34. D. Quartz schist, near Stevenson station, Maryland. Contains quartz, muscovite, tourmaline, micro- cline, zircon, and iron stains. Described by Bayley, Bull. U. S. Geol. Survey No. 150, 1898, p. 302. Analy- sis by E. A. Schneider. A B C D Si0 2 74. 22 83. 69k a 92. 00 91. 65 A1 2 0 3 10. 61 7. 50 4. 21 1. 59 Fe 2 0 3 7. 45 1. 81 1. 80 3. 57 FeO . 85 . 38 .21 1. 48 .35 . 17 CaO . 56 .39 .04 None. Na 2 0 2. 12 2. 46 . 16 . 07 k 2 o 1. 08 2. 61 1. 16 1. 93 h 2 o &1. 79 . 72 & . 96 . 60 Ti0 2 .16 Trace? . 14 . 13 PXL .21 None. MnO None. Trace. Trace. 100. 32 99. 91 100. 68 99. 92 a 84.13 per cent quartz, 7.87 per cent combined silica. & Loss on ignition. METAMORPHOSED SHALES. Shales, slates, phyllites, and mica schists form a continuous series of rocks which can be derived from clay, mud, or silt by progressive dehydration and crystallization. Some mica schists, of course, are traceable back to igneous rocks, but they fall outside of the present category. In order to study the development of schists from shales or clays, we must consider what compounds the latter contain capa- ble of dehydration and what are produced in this class of metamor- phoses. This ground has already been partly covered in the two preceding chapters. The final products of rock decomposition, apart from those that are removed in solution, are hydroxides of iron and aluminum; free silica, anhydrous or opaline; and hydrous silicates of iron, aluminum, and magnesium. The simple hydroxides offer the least difficulties in the way of interpretation. The iron com- pounds yield hematite, which is a common mineral in the metamor- phic schists, and which, in presence of organic matter, may be reduced to magnetite . 1 The aluminum hydroxides may furnish dia- spore if the dehydration is partial, or corundum when the reaction is complete. Opaline silica loses water and becomes converted 1 If a bed of limonite be regarded as a sedimentary rock, a bed of hematite may be its metamorphic equivalent. METAMORPHIC ROCKS. 609 into quartz. These changes are of the simplest character, but it is not certain that they always take place. It is possible that the colloidal silica may react upon the colloidal hydroxides, and form silicates anew; but I am not sure that this class of reactions has been proved. They are conceivable, and therefore can not be left out of account. The known changes, as I have stated them, are those of the compounds themselves when not commingled with other sub- stances. Hematite, magnetite, corundum, and quartz can be formed in the manner indicated; and hematite or magnetite schists (schists containing these minerals in conspicuous proportions) are not rare. The itabirite of Brazil is a rock of this kind, containing hematite, magnetite, and quartz . 1 Similar rocks have been described by H. Coquand 2 in France, and O. M. Lieber 3 in South Carolina. Co- quand’s rock is described as equivalent to a mica schist containing specular hematite in place of mica. Itabirite from Okande Land, West Africa, is reported by O. Lenz 4 as containing quartz, hematite, and magnetite, with quartz predominating. Another example from the Gold Coast, described by C. W. Gumbel , 5 contains also muscovite, ilmenite, and free gold. A German schist examined by C. Lossen 6 consisted of specular hematite and quartz. FERRUGINOUS SCHISTS. The ferruginous schists of the Lake Superior region may properly be mentioned here. According to C. R. Van Hise , 7 they are derived from carbonate rocks which he calls sideritic slates. These, by oxida- tion, pass into limonitic or hematitic slates, and from the latter the schists are derived. Ferruginous cherts are also formed, and some banded rocks of chert and hematite which Van Hise calls jaspilite. The silicification of the original siderite is attributed to the action of silica contained in percolating waters. The following analyses of the schists were made in the laboratory of the United States Geological Survey : 1 See Zirkel, Lehrbuch der Petrographie, 2d ed., p. 570, for references. 2 Bull. Soc. g6ol. France, 2d ser., vol. 6, 1849, p. 291. 3 Rept. Survey South Carolina, 1855, pp. 89-94; 1857, p. 79; 1858, p. 107. * Verhandl. K.-k. geol. Reichsanstalt, 1878, p. 168. 6 Sitzungsb. K. Akad. Wiss. Munchen, 1882, p. 183. 6 Zeitschr. Deutsch. geol. Gesell., vol. 19, 1867, p. 614. Zirkel refers also to Norwegian examples reported by J. H. L. Vogt in a memoir which I have not seen. 7 A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 830-842. See also the literature there cited, and especially Mon. U. S. Geol. Survey, vol. 28, 1895, by C. R. Van Hise and W. S. Bayley. On the metamorphism of oil shales by the combustion of their hydrocarbons, see R. Arnold and R. Ander- son, Jour. Geology, vol. 15, 1907, p. 750. 97270°— Bull. 616—16 39 610 THE DATA OF GEOCHEMISTRY. Analyses of ferruginous schists. A. Grunerite-magnetite schist, Marquette region, Michigan. Contains griinerite, magnetite, and quartz. Described by C. R. Van Hise and W. S. Bayley in Mon. U. S. Geol. Survey, vol. 28, 1895. Analysis by H. N. Stokes. B. Actinolite-magnetite schist, Mesabi Range, Minnesota. Described by W. S. Bayley, Am. Jour. Sci., 3d ser., vol. 46, 1893, p. 178. Consists of actinolite and magnetite. Analysis by W. H. Melville. A B Si0 2 46.25 12.35 A1 2 0 3 .92 .10 Fe 2 0 3 30. 62 58». 68 FeO 16.92 21.34 MrO 2.13 4. 08 CaO 1.69 1.91 NaaO None. Trace. H 2 0 .42 .19 Ti0 2 None. .12 p 9 0* .07 .25 MnO 1.01 1.22 CuO Trace. 100. 03 100. 24 DEHYDRATION OF CLAYS. Rocks like those just considered, obviously, may vary from nearly pure amphibole to nearly pure iron ore, and the quartz-bematite schists may range between the two extremes in the same way. In all cases, however, the final product represents the dehydration of hy- droxides, followed by partial reduction in the case of the magnetite schists. The origin of the hydroxides, whether from carbonates or from silicates, is a separate question. The hydrous silicates of the sediments are chiefly those of alumi- num. Some iron compounds also occur, such as glauconite, chloropal, or nontronite, but their mode of decomposition when dehydrated is not clearly known. In many cases, probably, they break down into ferric oxide and quartz; but they also, doubtless, contribute to the formation of less hydrous minerals, like staurolite and chloritoid. Of these species, more later. Magnesian silicates must also exist in the sediments, as talcose or serpen tinous matter, but their dehydra- tion products have already been discussed . 1 Many hydrous silicates of aluminum have been described. A few of them are definite, others are more or less doubtful. Some, prob- ably, are colloidal mixtures, which should not be formulated as distinct 1 See p. 604, ante. METAMORPHIC ROCKS. 611 chemical compounds. The following minerals in this class are rec- ognized by Dana as true species : Kaolinite Halloysite Newtonite Cimolite Montmorilionite Pyrophyllite Allophane Collyrite Schrotterite . . . . H 4 Al 2 Si 2 0 9 . H 4 Al 2 Si 2 0 9 +aq. H 8 Al 2 Si 2 O u +aq. H 6 Al 4 Si 9 0 27 +3 aq.(?) .H 2 Al 2 Si 4 0 12 +n aq. H 2 Al 2 Si 4 0 12 . Al 2 Si0 6 .5aq. Al 4 Si0 8 .9aq. Al 16 Si 3 O 30 .30aq. To this list rectorite 1 and leverrierite 2 should probably be added. Leverrierite, as described by P. Termier, has the composition of mus- covite, with hydrogen replacing potassium, and a little iron equiv- alent to aluminum. Its formula, then, is HAlSi0 4 , or H 3 Al 3 Si 3 0 12 , corresponding to muscovite, H 2 KAl 3 Si 3 0 12 . Rectorite, according to R. N. Brackett and J. F. Williams, has the same composition, plus an excess of water, which is driven off when the mineral is dried at 110°. Possibly the mineral kryptotile, an alteration product of kornerupine or prismatine, may be a compound of the same order. 3 Silicates of this type, if their existence should be definitely estab- lished, would probably be found to be widely diffused and to play an important part in the development of phyllite or mica schist. They should take up potassium from percolating solutions, forming musco- vite — a probability which deserves to be investigated with great care. Upon complete dehydration all of the silicates in the list except collyrite and schrotterite should break down into mixtures of Al 2 Si0 5 and Si0 2 . Al 2 Si0 5 represents empirically, the three min- erals andalusite, kyanite, and sillimanite, which are isomeric but not identical. No other anhydrous silicate of aluminum alone is known to occur in nature. These three species, moreover, are all character- istic of the metamorphic schists, and must have been formed in most cases by some such process as that just indicated. Sometimes, how- ever, other sources are to be assumed. For example, K. Dalmer 4 has described a phyllite containing muscovite and chlorite, which, by contact metamorphism, has been transformed into a biotite-andalusite schist. In this instance the andalusite seems to have been produced by a reaction between the two antecedent species. On the other hand, it has been shown by W. Vernadsky 5 6 that sillimanite is a normal con- stituent of hard porcelain, in which it is derived from kaolinite; and also that kyanite and andalusite are convertible into sillimanite by 1 Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 16. 2 Bull. Soc. min., vol. 22, 1899, p. 27. 3 See J. Uhlig, Zeitschr. Kryst. Min., vol. 47, 1910, p. 215, and A. Sauer, Zeitschr. Deutsch. geol. Gesell., vol. 38, 1886, p. 705. * Neues Jahrb., 1897, Band 2, p. 156. 6 Bull. Soc. min., vol. 13, 1890, p. 256. See also J. W. Mellor, Jour. Soc. Chem. Ind., vol. 26, 1907, p. 375. 612 THE DATA OF GEOCHEMISTRY. heating to a temperature of 1,320° to 1,380°. Kyanite often occurs in mica schist, and also in long, bladed crystals embedded in quartz. All three species alter into mica, 1 so that here we have a group of facts which bear obviously upon the interpretation of metamorphic processes. We do not yet know, however, the conditions which deter- mine the formation in a metamorphic rock of one or another of the three isomers. The chemical structure of the particular hydrous silicate from which andalusite, kyanite, or sillimanite has been derived probably has a distinct influence upon the reaction. Temper- ature, as shown by Vernadsky, must also be taken into account, and so, too, must pressure. The three minerals differ in density, and pressure may well help to determine which species shall form. The specific gravity of andalusite is near 3.2, that of sillimanite about 3.25, and that of kyanite varies little from 3.6. Kyanite, then, would be likely to appear under the greatest pressures and andalusite under the least, other conditions being equal. The problem is complicated, however, by the fact that the same rock often contains more than one of these minerals, together with products derived from them. The argillite of Harvard, Massachusetts, according to B. K. Emerson, 2 contains andalusite inclosing sillimanite, both in every stage of alter- ation to muscovite. The argilhtes of this region, modified by intru- sions of granite, show a zonal system of changes. Where the tem- perature was lowest, andulusite and sillimanite form. With more intense heat, staurolite and garnet appear. Influx of alkaline waters from the heated granite changes these species to muscovite, while nearest the granite feldspars develop. Staurolite, HAl 5 FeSi 2 0 13 , specific gravity 3.75, is another mineral of the metamorphic schists, and one closely allied to the andalusite group. Its formation evidently requires the presence of iron in the sediments, and also conditions of temperature and pressure which could permit the retention of water. Garnet is one of its common associates, and so, too, are sillimanite and kyanite. Its most fre- quent matrix is mica schist; but its mode of formation is not yet clearly understood. Staurolite is always contaminated by inclusions of other substances, and it alters readily into mica. With more iron and possible hydration, schists are formed con- taining chloritoid or ottrelite. Chloritoid has the formula H 2 FeAl 2 Si0 7 ; but that of ottrelite is not certain. The best evi- dence goes to show that the two minerals are alike in type, except that chloritoid is an orthosilicate, and ottrelite a trisilicate. On this supposition the two formulae become A10 2 Fe.Si0 4 .A10H.H. A10 2 Fe.Si 3 0 8 .A10H.H. Chloritoid. Ottrelite. 1 The reported alteration of kyanite into steatite is most questionable. Probably a compact muscovite (damourite) has been mistaken for talc. 2 Bull. Geol. Soc. America, vol. 1, 1889, p. 559. METAMOEPHIC EOCKS. 613 Magnesium may replace iron to some extent, and in the Belgian ottrelites manganese plays a similar part. By dehydration, chlori- toid would become A10 2 Mg.Si0 4 .Al, or Al 2 MgSi0 6 , which is the formula of the aluminous constituent of augite and hornblende, and also of the imperfectly known mineral kornerupine. A relation between chloritoid and these silicates is therefore suggested, but what its real significance may be is unknown. Broadly considered, chloritoid and ottrelite belong to a group of silicates intermediate between the micas and the chlorites, from either of which groups they may be derived, or into which they may alter. In the ottrelite schists of Vermont, according to C. L. Whittle, 1 chlorite is derived from ottrelite, and the latter mineral was one of the last to form. In the Belgian phyllites studied by J. Gosselet 2 mica sometimes replaces ottrelite. The formation of ottrelite after the other min- erals of the schists was also noted by W. M. Hutchings 3 in a sericite- ottrelite-ilmenite phyllite from Cornwall, and by J. E. Wolff 4 in a rock found at Newport, Rhode Island. In a collection of rocks from the Transvaal, J. Gotz 5 found ottrelite schist, andalusite schist, and an intermediate phase containing both ottrelite and andalusite. Ottrelite and chloritoid are probably often confounded. At all events, chloritoid rocks have been less frequently described. C. Bar- rois 6 has reported them from the lie de Groix, France; a garnet- chloritoid-quartz schist from Japan has been described by B. Koto; 7 and a rock from the province of Salzburg, Austria, studied by A. Cathrein, contained about 64 per cent of chloritoid, with 30 of quartz and some rutile. Other occurrences are weH summed up by F. Zirkel, 8 for both ottrelite and chloritoid. The abundant litera- ture, however, is mainly descriptive, and sheds little light upon the genesis of these minerals. The following analyses represent rocks characterized by the andalusite and chloritoid groups. All except one, by Klement, were made in the laboratory of the United States Geological Survey. 1 Am. Jour. Sci., 3d ser., vol. 44, 1892, p. 270. 2 Annales Soc. gdol. du Nord, vol. 15, p. 185. 3 Geol. Mag., 1889, p. 214. 4 Bull. Mus. Comp. Zool., vol. 16, 1890, p. 159. 6 Neues Jahrb., Beil. Band 4, 1886, p. 143. 6 Annales Soc. g6ol. du Nord, vol. 11, 1884, p. 18. 7 Jour. Coll. Sci. Japan, vol. 5, 1893, p. 270. 8 Lehrbuch der Petrographie, 2d ed., vol. 3, pp. 282, 294, 303-306. 614 THE DATA OF GEOCHEMISTRY. Analyses of andalusite and chloritoid rocks. A. Andalusite schist, Mariposa County, California. Analysis by W. F. Hillebrand. Described by H. W. Turner, Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 1, 1896, p. 691. Contains quartz, biotite, andalusite, sericite, and minor accessories. B. Chiastolite schist, Mariposa County, California. Analysis by G. Steiger. Described by Turner, Bull. U. S. Geol. Survey No. 150, 1898, p. 342. Contains andalusite (chiastolite), sillimanite, mica, etc. C. Andalusite hornfels, Mariposa County. Analysis by Steiger. Described by Turner, op. cit., p. 342. Contains quartz, andalusite, mica, etc. D. Andalusite schist, Skamania County, Washington. Analyzed and described by W. T. Schaller, BulL U. S. Geol. Survey No. 262, 1905, p. 105. Contains andalusite, 35 per cent; quartz, 32 per cent; muscovite, 27 per cent; and minor accessories. E. Kyanite schist, Serra do Gigante, Brazil. Analysis by Hillebrand. Described by O. A. Derby, Am. Jour. Sci., 4th ser., vol. 7, 1899, p. 343. Consists mainly of kyanite, chlorite, sericite, quartz, and rutile. F. Sillimanite schist, San Diego County, California. Analyzed and described by Schaller, Bull. No. 262, 1895, p. 98. Mainly quartz, 69 per cent, and sillimanite, 31 per cent, neglecting water and minor accessories. G. Chloritoid-phyllite, Liberty, Maryland. Analyzed by L. G. Eakins. Called * ‘ ottrelite-phyllite ’ ’ by G. H. Williams, but the characteristic mineral is chloritoid. See Bull. U. S. Geol. Survey No. 228, p. 59. H. Ottrelite schist, Montherm6, Belgium. Analyzed by C. Element, described by A. F. Renard. Renard’s memoirs on the phyllites of the Ardennes (Bull. Mus. roy. hist. nat. Belgique, vol. 1, 1882, p. 212; vol. 2, 1883, p. 127; vol. 3, 1884, p. 230) are rich in data concerning rocks of this class. For this particular schist see vol. 3, p. 255. It contains ottrelite, 46.11 per cent; sericite, 23.35 per cent; and quartz, 23.15 per cent. A B c D E F G H Si0 2 64. 28 62. 15 65. 10 57. 18 38. 32 75. 54 34. 92 51. 93 A1A 17. 28 19. 34 17. 77 34. 10 28. 16 18. 65 32. 31 27. 45 Fe 2 0 3 1. 10 4. 23 1. 95 .54 2. 24 .35 10. 21 2. 01 FeO. 5. 34 2. 25 3. 29 .28 4. 02 .06 8. 46 8. 10 MgO 2. 57 1. 88 1. 43 .10 12. 04 None. 1. 13 1. 20 CaO 1. 19 1. 50 1. 38 .63 .32 CO o .36 .18 Na 2 0 .91 1. 60 2. 25 .39 .16 None. 2. 12 .79 K 2 0 2. 93 3.07 2. 45 2. 57 1. 11 None. 1. 87 1.60 H 2 0- .20 .19 .47 .69 .55 1. 10 1 c; OQ 1 Q QO H 2 0+ 2. 72 1. 79 2. 49 2. 02 7. 46 3. 67 > O. > O. V4 Ti0 2 .65 .80 .72 .66 4.93 .48 J 3.37 .92 Zr0 2 .02 .09 .06 C .43 1. 12 1. 21 1. 05 so 3 . 13 .03 s Trace. F . 22 . 12 Trace? Cl None. Trace. PA .27 . 15 . 14 .53 .47 Trace. .23 MnO .09 Trace. None. None. .16 Trace. .57 ■Ra.O . 10 . 04 None. .04 SrO Trace. None. None. Trace? Trace. (Ni,Co)0 .04 Li 2 0 Trace. None. None. None. Trace. FeS 2 .28 .10 100. 06 100. 46 100. 80 100. 03 100. 07 100. 04 100. 27 99. 72 MICA SCHIST. A great variety of other schists, corresponding to the variations in the sediments themselves, have received special descriptive names. Graphite schists, derived from carbonaceous shales; tourmaline schists, containing tourmaline, and garnet-mica schists are good examples. The commonest type of all, however, is the ordinary mica or sericite schist, which is essentially a mixture of quartz and mica, METAMORPHIC ROCKS. 615 with varying accessories. A p aragonite schist contains the soda mica, p aragonite, instead of the commoner muscovite. A shale passes into a slate; in that fine scales of mica develop, forming a phyllite, and with more complete recrystallization a mica schist is produced. Mica schists also originate from the alteration of a granitic detritus con- sisting of quartz and feldspar , 1 the latter mineral changing to mus- covite, or, under undetermined conditions, to biotite. Chlorite, epi- dote, garnet, tourmaline, and feldspars are common accessory min- erals in rocks of this class. The following analyses of mica schists were made in the Survey laboratory: Analyses of mica schists. A. Quartz-sericite schist, Mount Ascutney, Vermont. Analyzed by W. F. Hillebrand. Described by R. A. Daly in Bull. U. S. Geol. Survey No. 209, 1903. B. Sericite schist, Ladiesburg, Maryland. Analyzed by G. Steiger. Described by W. S. Bayley in Bull. U. S. Geol. Survey No. 150, 1898, p. 317. C. Sericite schist, Marquette region, Michigan. Analysis by Steiger. Described by C. R. Van Hise and W. S. Bayley, Mon. U. S. Geol. Survey, vol. 28, 1895. Mainly sericite and quartz. D. Mica schist, Crystal Falls district, Michigan. Analyzed by H. N. Stokes. Described by H. L. Smyth, Mon. U. S. Geol. Survey, vol. 36, 1898, p. 274. Contains biotite, quartz, some microcline, and magnetite. E. Mica schist, near Gunflint Lake, Minnesota. Analyzed by T. M. Chatard. Contains biotite, quartz, feldspar (?), and pyrite, as reported by Van Hise. F. Feldspathic mica schist, Mariposa County, California. Analyzed by Hillebrand. Described by H. W. Turner, Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 1, 1896, p. 691. Contains quartz, feldspar, biotite, muscovite, apatite, and specular iron. A B c D E F Si0 2 90. 91 57. 24 70. 76 64. 71 64. 77 70. 40 A1 2 0 3 4. 18 23. 48 14. 83 16.43 14.45 14. 70 Fe 9 0o .22 3. 19 1. 46 1. 83 1.84 . 65 FeO 1. 27 4. 87 3. 09 3. 84 4. 54 2. 57 MgO .37 .93 1. 99 2. 97 2. 34 1.47 CaO .22 .09 .36 .08 2. 33 1. 63 Na 2 0 . 77 1. 18 . 47 . 11 1. 37 3. 17 K 2 0 .58 3. 55 3. 50 5. 63 5. 03 3. 46 H 2 0- .06 .33 .09 . 31 . 07 . 19 h 2 o+ . 74 4. 65 2. 70 2. 79 1. 92 . 91 Ti0 2 .28 .08 .33 .72 .60 .51 Zr0 2 .02 co 2 . 18 .41 PXL .05 .09 .26 .02 .20 .05 S0 3 None. .60 F Trace. MnO Trace. None. Trace. .11 .08 BaO Trace. .09 SrO Trace. LioO Trace. C .10 .15 FeS 2 .11 100. 06 99. 68 99. 84 99. 44 100. 58 100. 03 i See C. R. Van Hise, Bulk Geol. Soc. America, vol. 1, 1899, p. 206, on schists from the Black Hills. 616 THE DATA OF GEOCHEMISTRY. Before leaving the subject of mica schist a word of caution may not be superfluous. It is often assumed that the mica in such a rock has been derived from the alteration of feldspathic particles contained in the original sediments, and this no doubt is frequently the case. The same process operates that is traced in the sericitiza- tion of an igneous rock, but it is not necessarily general. We have seen that muscovite can be formed from andalusite, for instance, and the latter probably from clay substance. In short, micas may form in a number of different ways, so that no single set of reactions can account for all of its occurrences. Sometimes its source can be determined, but not always. Many schists contain tourmaline as an essential constituent. Dumortierite also occurs in them, perhaps more often than is com- monly supposed. These species are borosilicates, and their generation is usually attributed to the agency of boron-bearing gases or vapors emitted from heated magmas along their contacts with sedimentary deposits. Boron compounds, and fluorine compounds also, exist in volcanic emanations, as was shown in Chapter VIII, and they .prob- ably produce, in many instances, the effects just ascribed to them. But here again caution is necessary. We do not know how widely boron and fluorine may be disseminated in rock-forming mate- rials, for their determination in traces is very difficult and rarely attempted. Fluorine must be abundantly diffused as a constituent of the ubiquitous mineral apatite, and boron may be equally com- mon. We observe its concentration in tourmaline, but we can not be positive as to its origin except in certain individual cases. One of these seems to be the contact between mica schist and granite on Mount Willard, in the White Mountains of New Hampshire, as described by G. W. Hawes . 1 Here there are seven well-defined zones, as follows: 1. Argillitic mica schist, chloritic. 2. Argillitic mica schist, biotitic. 3. Tourmaline hornstone. 4. Tourmaline veinstone. 5. Mixed granite and schist. 6. Granite porphyry, biotitic. 7. Normal granite, hornblendic. This contains quartz, albite, orthoclase, horn- blende, and some biotite. In the porphyry, biotite entirely replaces the hornblende. The remarkably complete series of analyses by Hawes is given in the next table. » Am. Jour. Sci., 3d ser., vol. 21,-1881, p. 21. METAMORPHIC ROCKS. 617 Analyses of granite and mica schist near contact , Mount Willard. A. The normal Albany granite. B. Porphyry, 3 feet from contact. C. Porphyry, 2 inches from contact. D. Tourmaline veinstone, on contact. E. Tourmaline homstone, 1 foot from contact. F. Schist, 15 feet from contact. G. Schist, 50 feet from contact. H. Schist, 100 feet from contact. A B C D E F G H Si0 2 72. 26 73. 09 71. 07 66. 41 67. 88 66. 30 63. 35 61. 57 AJA 13. 59 12. 76 12. 34 16. 84 14. 67 16. 35 19. 69 20. 55 FeA 1. 16 1. 07 2. 25 1. 97 2. 37 .95 .72 2. 02 FeO.. 2. 18 4. 28 4. 92 5. 50 3. 95 5. 77 5. 48 4. 28 MgO .06 .09 .19 1. 71 1. 29 1. 63 1. 77 1. 27 CaO 1. 13 .30 .55 .37 .30 .24 Trace. .24 Na 2 0 3. 85 3. 16 2. 84 1. 76 3. 64 1. 11 1. 12 .68 K 2 0 5. 58 5. 10 5. 53 .56 4. 08 3. 40 3. 47 4. 71 H 2 0 .47 .73 .72 1. 31 1. 01 3. 02 3. 73 4. 09 Ti0 2 .45 .40 .27 1. 02 .93 1.28 1. 00 1. 10 BA. 2. 96 . 97 Trace. ■^2^3 F . . .25 Trace. MnO Trace. .08 Trace. .12 . 11 Trace. .16 .10 100. 73 101. 06 100. 68 100. 78 101. 20 100. 05' 100. 49 100. 61 The dehydration in passing from schist to granite is here very obvious, but the sudden appearance of boric oxide is more striking. That its concentration was brought about by pneumatolytic processes is the most reasonable hypothesis by which to account for its pres- ence at the line of contact and its absence elsewhere. The mineral- ogical composition of the rocks D to H, as given by Hawes, presents a still clearer picture to the mind of the changes which have occurred : Mineralogical composition of tourmaline rocks and mica schist, Mount Willard. D E F G H Quartz 50. 03 50. 82 1 29. 67 45. 15 30. 17 36. 87 Muscovite 44. 53 49. 30 Biotite | 43. 89 Chlorite ) 6. 65 13. 70 8. 62 Ilmenite 1.94 1. 77 2. 43 1. 90 2. 09 Magnetite 2. 86 3.44 1. 38 1. 04 2. 93 Tourmaline 45. 95 14. 92 Here we see that the chlorite of the schist alters to biotite, by dehy- dration, as the contact is approached, and that the tourmaline has been formed largely at the expense of the micas. The absence of feldspar, which is abundant in the granite, is also noticeable. On the granite side of the contact the rocks are feldspathic; on the schist- ose side they are micaceous; at the contact neither feldspar nor mica is shown by Hawes’s figures. Probably both minerals have contrib- uted to the generation of tourmaline, which is related to both. Tourmaline often alters to mica, and tourmaline crystals are known inclosing cores of feldspar. 618 THE DATA OF GEOCHEMISTRY. GNEISS. , The gneisses form the largest group of metamorphic rocks, and represent both igneous and sedimentary formations. Some of them are plutonic rocks, structurally modified; others are recrystallized sedimentaries. The term “gneiss/ 7 unfortunately, has been used in quite different senses. For present purposes, J. F. Kemp’s defini- tion 1 may perhaps serve as well as any. He defines gneiss as a “lam- inated metamorphic rock, which usually corresponds in mineralogy to some one of the plutonic types.” The gneisses “ differ from schists in the coarseness of the laminations, but as these become fine they pass into schists by insensible gradations.” Under this definition any plutonic rock may have its gneissoid equivalent, and C. H. Gor- don 2 has proposed to name the gneisses accordingly. Thus we may have granitic gneiss, syenitic gneiss, dioritic gneiss, etc., including in the series foliated rocks derived from pyroxenite or peridotite. The common usage, however, is not quite so extreme, and the term gneiss is practically restricted to granular, laminated rocks analogous in composition to granite, syenite, or diorite. Chemically these gneisses differ very little from their igneous equivalents, but those derived from sedimentary rocks are likely to he relatively poor in alkalies and to contain minerals of calcareous origin. In some cases gneisses of sedimentary origin contain impurities of organic deriva- tion, either coaly or graphitic. For example, in a gneiss from the Black Forest, H. Rosenbusch 3 found coaly particles which contained nitrogenous matter, undoubtedly derived from organic substances. A convenient aid to nomenclature is that offered by Rosenbusch, 4 who calls gneiss of igneous origin “orthogneiss,” and that of sedi- mentary origin “paragneiss.” There are also descriptive names of the ordinary character, which indicate mineralogical peculiarities. Chlorite gneiss, cordierite gneiss, tourmaline gneiss, garnet gneiss, epidote gneiss, sillimanite gneiss, albite gneiss, muscovite gneiss, bio- tite gneiss, two-mica gneiss, plagioclase gneiss, and orthoclase gneiss are names of this kind. The sedimentary varieties are also named genetically, as pelite gneiss, psammite gneiss, arkose gneiss, etc., according to the derivation of the rock from shaly, sandy, or arkose materials. The following analyses of gneiss, with the exception of the Cana- dian example, were made by the chemists of the United States Geological Survey: 1 Handbook of rocks, 3d ed., p. 123. 2 Bull. Geol. Soc. America, vol. 7, 1895, p. 122. 8 Mitth. Gr. badisch. geol. Landes anstalt, vol. 4, Heft 1, 1899. * Elemente der Gesteinslehre, 2d ed., p. 484. METAMORPHIC ROCKS. 619 Analyses of gneisses. A. Sedimentary gneiss, St. Jean de Matha, Quebec, Canada. Analysis by N. N. Evans. Described by F. D. Adams, Am. Jour. Sci., 3d ser., vol. 50, 1895, p. 67. Adams gives several other analyses of gneisses. B. Quartz-biotite-gamet gneiss, Fort Ann, New York. Analysis by W. F. Hillebrand. Reported by J. F. Kemp to contain quartz, garnet, biotite, orthoclase, some plagioclase, and zircon. C. Average sample of mica gneiss, near Philadelphia, Pennsylvania. Analysis by Hillebrand. De- scribed by F. Bascom, Maryland Geol. Survey, Cecil County volume, 1902, p. 116. Contains quartz, muscovite, feldspars, and minor accessories. D. Gneiss from Dorsey’s Run, Maryland. Analysis by Hillebrand. Described by C. R. Keyes, Fif- teenth Ann. Rept. U. S. Geol. Survey, 1895, p. 697. Probably of sedimentary origin. E. Gneiss, probably sedimentary, Great Falls of the Potomac. Analysis by Hillebrand. Described by G. H. Williams, Fifteenth Ann. Rept. U. S. Geol. Survey, 1895, p. 670. F. Biotite gneiss, Upper Quinnesee Falls, Menominee River, Michigan. Analysis by R. B. Riggs. Described by G. H. Williams, Bull. U. S. Geol. Survey No. 62, 1890, p. 119. Contains biotite, soda ortho- clase, quartz, and accessory sphene, zircon, and apatite. G. Quartz-norite gneiss, Odessa, Minnesota. Analysis by H. N. Stokes. Described by W. S. Bayley, Bull. U. S. Geol. Survey No. 150, 1898, p. 358. Contains quartz, plagioclase, and pyroxene, with accessory biotite, garnet, pyrite, and magnetite. A B C D E F G Si0 2 61. 96 19. 73 65. 09 16. 37 .93 5. 64 2. 40 2. 40 3. 31 1. 93 .13 .58 .93 .01 .07 .11 .03 66. 13 15. 11 2. 52 3. 19 2. 42 1. 87 2. 71 2. 86 .24 1. 55 .82 J ?) None. .22 .03 48. 92 16. 57 4. 21 9. 18 5. 98 9. 69 2. 47 1. 56 } .68 78. 28 9. 96 1. 85 1. 78 .95 1. 68 2. 73 1. 35 .12 .83 .70 67. 77 16. 61 2. 06 1. 96 1. 26 1.87 4. 35 2. 35 } L69 61. 04 16. 97 ALOo Feb. 4. 60 1. 81 .35 .79 2. 50 } 1.82 1. 66 5. 58 3. 62 5. 99 1. 96 .55 } .43 MgO CaO Na 2 0 K 2 0 H 2 0- H 2 0+ Ti0 2 Zr0 2 C0 2 .19 PAR .11 S Fe 7 S 8 3. 73 FeS 2 4. 33 Cr 9 0o Trace. Trace. .16 .03 Trace. Trace. NiO Trace. .20 Trace. Trace. None. MnO Trace. .08 .02 Trace. Trace. BaO SrO Li 2 0 Trace. 99. 55 100. 12 99. 87 100. 26 100. 44 100. 11 98. 87 In a broad way the general order of change from clay to slate, shale, and metamorphic schists is well shown by a series of averaged analyses compiled by C. R. Van Hise. 1 The analyses chosen for combination were all of pelitic material. 1 A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 890, 891, 896. The data are all to be found in Bull. U. S. Geol. Survey No. 591, 1910; the shale average on p. 23. 620 THE DATA OF GEOCHEMISTRY. Average analyses of clay, shale, slate, and schist. A. Average of 12 analyses of clays and soils. B. Average or composite analysis of 78 shales. C. Average of 22 analyses of slates. D. Average of 5 analyses of schists. Si0 2 . ai 2 o. Fe 2 0 FeO. MgO CaO. Na 2 0 K 2 0. h 2 o. Ti0 2 C0 2 . it Cl... F.... MnO SrO. BaO. Li 2 0 FeS 2 C... A B C D 54. 28 58. 38 61. 90 65.74 14. 51 15. 47 16. 54 17. 35 ~ 6. 25 4. 03 2. 73 1. 90 . 77 2. 46 3. 63 3. 35 2. 99 2. 45 2. 99 1. 90 5.04 3. 12 1. 07 1. 25 ) 1. 21 1. 31 2. 57 1. 78 2. 12 3. 25 3. 15 3. 28 8. 41 5. 02 3. 84 2. 01 .42 .65 .82 .55 3. 53 2. 64 .59 None. .09 . 17 .04 .12 .08 .65 .03 .03 .02 Trace. Trace. Trace. .07 1 .08 Trace. Trace. .03 None. Trace. Trace. .05 .01 .05 Trace. Trace. Trace. . 11 .24 .81 .22 .58 100. 04 100. 46 100. 24 99. 99 In these figures, reading from clay to schist, we see a steady loss of water and of carbon dioxide. The latter has been gradually replaced by silica, and silica has also increased in proportion by its assumption as a cementing substance. Ferric iron, furthermore, is partly reduced to the ferrous state, and there is an apparent gain in alumina, which may be partly real, and so far due to cementation. The averages represent too few individual analyses to warrant any elaborate discussion of them, but they serve to illustrate the general tendency of the metamorphic processes. METAMORPHIC LIMESTONES. The metamorphism of limestone is effected by a variety of processes which are quite distinct in many particulars from those outlined in the preceding pages. A pure or relatively pure limestone may re- crystallize into a compact marble, as shown in the chapter upon the sedimentary rocks. If it contains magnesium carbonate, dolo- mite is produced; and the presence of iron may determine the for- mation of mixed carbonates, such as ankerite or mesitite. These changes are of the simplest character and call for no further dis- cussion now. METAMORPHIC ROCKS. 621 But pure limestones are relatively rare. Sandy or argillaceous impurities are generally present, and also silicates produced by reac- tions with infiltrating waters. When limestones of this sort are meta- morphosed, either dynamically or by contact with igneous injections, new minerals are generated, and the range of possibilities becomes very broad. Each impurity exerts its own peculiar influence, and operates to develop certain individual substances. Organic matter, for example, furnishes the material for graphite, which is very com- mon in metamorphosed limestones. In the Adirondack region there are numerous beds of white, crystalline limestone, thickly spangled with brilliant hexagonal plates of graphite; and these localities are typical of many others. When silica is the sole impurity of importance, it can crystallize as quartz, or react with the calcium carbonate to form the silicate, wol- lastonite. No more limpid crystals of quartz are known than those found in the cavities of Carrara marble. As for wollastonite, CaSi0 3 , it is often formed at contacts between limestone and igneous rocks, and it is also found disseminated through schists and gneisses. It must be remembered that shales and sandstones often contain cal- careous matter, which undergoes the same transformations that the concentrated limestones experience. Calcium carbonate in a siliceous sedimentary rock may easily become the progenitor of wollastonite, garnet, scapolite, epidote, and other calciferous species. Carbon dioxide is expelled, and sihcates are produced. The development of wollastonite at an igneous contact, or, indeed, in any metamorphic rock, has peculiar geologic significance. E. T. Allen and W. P. White 1 have shown that this mineral can be formed only at temperatures not exceeding 1,180°. Above that temperature it passes into the pseudohexagonal modification, which has often been prepared artificially, but is unknown as a natural species. The presence of wollastonite, then, is evidence that the rock containing it had recrystallized at some temperature below the transition point. If that degree of heat were ever exceeded in a contact zone, we should expect the pseudohexagonal silicate to appear; since it does not, we are justified in assuming that this form of metamorphism is always effected at lower temperatures. We thus obtain a definite datum point in what has been called the “ geologic thermometer.” The recrystallization of a sedimentary limestone containing limo- nitic impurities or hydroxides of aluminum will obviously produce inclusions of magnetite, hematite, or corundum. Magnetite has often been identified in crystalline limestones, and similar occurrences of corundum are not uncommon. The Burmese rubies, for example, are found in crystalline limestone, and so, too, are the red and blue 1 Am. Jour. Sci., 4th ser., vol. 21, 1906, p. 89. The memoir is prefaced by a note from G. F. Becker, who points out the geologic bearing of the observations. 622 THE DATA OF GEOCHEMISTRY. corundums of Newton, New Jersey. When alumina and silica are present together, the reaction with calcium carbonate leads to the formation of various silicates, the conditions which determine the appearance of each one, however, not being definitely known. Cin- namon garnet, vesuvianite, epidote, zoisite, and the scapolites are among the species which appear most frequently. Gehlenite also occurs, but more rarely; for example, in marble, at the classical locality of Monzoni in the Tyrol . 1 Metamorphosed limestone with inclusions of this class are common; for instance, in a belt extending from southwestern Maine to central Massachusetts. From two points in this belt, at Raymond and Phippsburg, Maine, crystallized anorthite has also been identified by analyses made in the laboratory of the United States Geological Survey . 2 The other feldspars as well, albite, orthoclase, and the plagioclases, are known as contact minerals or inclusions in crystalline limestones , 3 and also the micas muscovite, biotite, and phlogopite. Phlogopite is essentially a mineral of this group of rocks, its formation and that of biotite requiring the presence of magnesium compounds. To form scapolites, sodium chloride is necessary, but that may easily come from percolating waters, or from apatite. The alkalies required by the feldspars and micas may have a similar origin, or else be derived from impurities in the sedi- ments from which the limestones were formed. Nearly all limestones are more or less magnesian or ferruginous, facts which determine the formation of many metamorphic minerals. Magnesia, for instance, may crystallize by itself as periclase, and that species alters into brucite. Magnesia and alumina together give rise to spinel. With silica, magnesian silicates, often ferriferous, may form, such as forsterite, olivine, enstatite, and hypersthene. With lime and magnesia together, monticellite is produced, and also a wide range of pyroxenes and amphiboles. Augite, hornblende, diallage, diopside, actinolite, and tremolite are common in meta- morphic limestones, and the minerals of the chondrodite-humite series are also characteristic of these rocks in many localities. The white, yellow, and brown magnesian tourmalines are other species of this class. Furthermore, the oh vines, pyroxenes, amphiboles, and chondrodites alter into serpentine and talc, forming the ophicalcite marbles or verde antique . 4 1 See C. Doelter, Jahrb. K.-k. geol. Reichsanstalt, 1875, p. 239. Doelter also reports hematite in these marbles; and it has been identified by G. d’Achiardi in Carrara marble. 2 Bull. U. S. Geol. Survey No. 220, 1903, p. 27. Anorthite also occurs in the marble of Monzoni, in the Tyrol. See G. vom Rath, Zeitschr. Deutsche geol. Gesell., vol. 27, 1875, p. 379. 3 See, for example, G. Linck, Neues Jahrb., 1907, p. 21, on orthoclase from the dolomite of Campolongo. * In Mon. U. S. Geol. Survey, vol. 46, 1904, p. 221, W. S. Bayley described a talcose schist from the Aragon iron mine, Michigan, which was probably derived from a dolomite. An analysis of it, by G. Steiger, is given, and also its mineraiogical composition. On the origin of secondary silicates in limestones see W. L. Uglow, Econ. Geology, vol. 8, pp. 19, 215, 1913. METAMORPHIC ROCKS. 623 In a Scottish dolomitic marble containing forsterite, tremolite, diopside, and brucite, J. J. H. Teall 1 has observed a dedolomitiza- tion due to the silica tion of the double carbonate. That changes to diopside without change of ratios, and the partly altered rock shows the two species in juxtaposition. The metamorphosis was effected by a plutonio intrusion, and where silica was deficient, brucite appeared. Probably in the latter case magnesium carbonate was first reduced to periclase, MgO, which was later hydrated to brucite, Mg0 2 H 2 . The mixture of calcite and brucite is identical with the predazzite of the Tyrol. 2 It may be noted here that certain of the Adirondack limestones are regarded by J. F. Kemp 3 as having been originally siliceous dolomites, in which the silica and magnesia have segregated as pyroxene. In northern New Jersey, according to L. G. Westgate, 4 a quartz rock and a quartz-pyroxene rock have been formed by the metamorphism of limestones. In addition to the minerals already named, the crystalline lime- stones contain many other less important species. Apatite, fluorite, rutile, perofskite, titanite, dysanalyte, and zircon are among them. By the reduction of sulphates, a considerable number of sulphides may be formed. At Carrara, for instance, G. d’Achiardi 5 found realgar, orpiment, sphalerite, pyrite, arsenopyrite, galena, chalcocite, and tetrahedrite ; and also native sulphur and gypsum. Pyrrhotite and molybdenite have been identified at other localities, and in the famous Binnenthal, in Switzerland, several rare sulphosalts occur in a crystalline dolomite. In short, the list of minerals now known as existing in metamorphosed limestones must comprise at least 70 species, and possibly more. 6 The rocks thus formed from limestones and dolomites, or from mixtures of these with siliceous material, can vary from a nearly pure, recrystallized carbonate to an indefinite aggregate of silicates alone. Even in a single bed the rocks may range from one extreme to the other. Analyses of such rocks, therefore, have little signifi- cance and are not often made. Three examples from the silicate side of the group may serve to illustrate the variety of composition: 1 Geol. Mag., 1903, p. 513. A similar example is reported by F. H. Hatch and R. H. Rastall, Quart. Jour. Geol. Soc., vol. 66, 1910, p. 507. See also T. Crook, Geol. Mag., 1914, p. 339. 2 See ante, p. 570. 3 Bull. Geol. Soc. America, vol. 6, 1894, p. 241. In the same volume, p. 263, C. H. Smyth discusses another group of Adirondack limestones which were metamorphosed along contacts with gabbro. « Am. Geologist, vol. 14, 1894, p. 308. 3 Atti Soc. toscana sci. nat., Pisa, vol. 21, 1905. 8 A list is given by F. Zirkel in Lehrbuch der Petrographie, 2d ed., vol. 3, p. 448. Seealso B. Lindemann, Neues Jahrb., Beil. Band 19, 1904, p. 197. For the Ceylonese localities, see A. K. Coom&ra-Sw&my, Quart. Jour. Geol. Soc., vol. 58, 1902, p. 399. J. F. Kemp and A. Hollick have described the crystalline limestones of Warwick, New York, in Annals New York Acad. Sci., vol. 7, 1893, p. 644. 624 THE DATA OF GEOCHEMISTRY. Analyses of metamorpkic silicate rocks. A. Wollastonite gneiss, Amador County, California. Analysis by W. F. Hillebrand. Described by H. W. Turner, Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 1, 1896, p. 521. Consists mainly of wollas- tonite, but garnet, quartz, and titanite are also present. B. Prehnite rock, Black Forest, Germany. Analysis by C. Schnarrenberger. Described by H. Rosen- busch, Mitt. Gr. badisch. geol. Landesanstalt, vol. 5, Heft 1, 1905. Estimated to contain 46.2 per cent prehnite, 37.9 albite, 13.8 actinolite, and 3.2 kaolin and nontronite. Probably formed from a marl con- taining 34.5 per cent of carbonates with 65.5 silicates and quartz. C. Garnet rock, Black Forest. Analysis by Schnarrenberger. Described by Rosenbusch, loc. cit. Probably derived from an original mixture of 48 per cent carbonates and 52 of silicates, chiefly kaolin. Contains about 75 per cent garnet, 10 per cent soda-potash mica, and 15 per cent hornblende. A B C Si0 2 50. 67 50. 65 41. 01 A1 2 0, 6. 37 19. 54 18. 50 Fe^Oj. .31 3. 34 6. 57 FeO.. . 50 None. 11. 06 MgO .58 3. 92 11. 02 fkO 40. 34 16. 11 10. 31 Na.„0_ . - . 14 3. 91 .48 k 2 o .22 .84 .31 h 2 o .39 a 3. 10 1. 18 Ti0 2 . 20 Trace. co 2 . 52 MnO Trace. 100. 24 100. 41 100. 44 a Loss on ignition. DIAGNOSTIC CRITERIA. It is generally desirable, but not always easy, in the study of a metamorphic rock, to determine whether it was of igneous or sedi- mentary parentage. For this purpose various criteria have been proposed, and chemical analysis furnishes some of them. On the chemical side the problem has been well discussed by E. S. Bastin , 1 who points out a number of possibilities. First, a study of analyses by the methods laid down in the quan- titative classification of igneous rocks. In many cases the “norm” of a sedimentary rock is identical with that of some igneous rock, as shown in Washington’s tables . 2 In such instances no definite con- clusion can be reached from chemical evidence alone. But if the “norm” agrees with that of no known igneous rock, the analysis probably, but not certainly, indicates a sedimentary origin. Secondly, the manner in which the sedimentaries are formed suggests other chemical criteria. In most igneous rocks soda is in excess of potash, but decomposition changes the ratio, which, in 1 Jour. Geology, vol. 17, 1909, p. 445. See also J. D. Trueman, idem, vol. 20, 1912, p. 311, and rejoinder by Bastin, idem, vol. 21, 1913, p. 103. 2 For example, an amphibolite derived from limestone was shown by F. D. Adams (Jour. Geology, vol. 17, 1909, p. 1) to fall under the heading of auvergnose. METAMORPHIC ROCKS. 625 sedimentary rocks, is often reversed. Dominance of potash over soda, then, is an indication of sedimentary origin. Dominance of magnesia over lime is another similar criterion, and any excess of alumina over the 1 : 1 ratio necessary to balance lime and alkalies is still another. Unusually high silica also affords presumptive evi- dence, which by itself is not conclusive, that a rock was derived from sediments. When two of these criteria are applicable to a meta- morphic rock, there is a strong presumption established in favor of its former sedimentary character. When three apply, the conclu- sion is almost certain, and the concurrence of all amounts to positive proof. The analyses, however, must relate to fresh, unweathered material, and the criteria proposed apply only to silicates which might be metamorphosed plutonics or eruptives. 97270°— Bull. 616—16 10 CHAPTER XV. METALLIC ORES. DEFINITION. From a strictly scientific point of view, the terms metallic ore and ore deposit have no clear significance. They are purely conventional expressions, used to describe those metalliferous minerals or bodies of mineral having economic value, from which the useful metals can be advantageously extracted. In one sense, rock salt is an ore of sodium, and limestone an ore of calcium; but to term beds of these substances ore deposits would be quite outside of current usage. In the previous chapters of this work several forms of ore deposit have been described; and therefore the present chapter is in some measure supplementary. Its purpose is to deal with the subject more fully, and especially to give details concerning certain groups of ores which have been left out of account hitherto. Little has been said so far of the sulphides, and these are among the most important of economic minerals. Their genesis, their deposition in veins or pock- ets, their alterations and transferences are yet to be considered. Upon the classification of ore deposits there has been much contro- versy, and various systems are in vogue . 1 To the geologist or miner this question is most important; to the chemist it is less fundamental. Regarded from the genetic side, a large part of the field has been already covered; and it is easy to see that many ore deposits, if not all, fall under the headings of earlier chapters. For example, cer- tain metallic ores occur as volcanic sublimates; others, like the titan- iferous magnetites, are magmatic segregations, or local developments of igneous rocks. The sands and gravels that yield chromite, tin- stone, gold, platinum, etc., are detrital in character; many manganese and iron ores are sedimentary rocks, and from the latter metamorphic beds of magnetite or hematite are derived. Some ore bodies are resi- dues from the concentration of limestones; others represent meta- somatic replacements; others again are deposited or precipitated 1 For recent papers and works on this subject, see F. Po§epn£, Trans. Am. Inst. Min. Eng., vol. 23, 1893, p. 197; J. H. L. Vogt, idem, vol. 31, 1901, p. 125; L. De Launay, Contribution k l’6tude des gites m^talli- f&res, Paris, 1897; J. F. Kemp, Ore deposits of the United States and Canada, New York, 1900; W. H. Weed and J. E. Spurr, Eng. and Min. Jour., vol. 75, 1903, p. 256; It. Beck, Lehre von den Erzlagerstatten, Berlin, 1903, and its English translation by Weed, New York, 1905; A. W. Stelzner and A. Bergeat, Dio Erzlagerstatten, Leipzig, 1904; C. R. Van Hise, A treatise on metamorphism: Mon. U. S. Geol. Survey, vol- 47, 1904, chapter 12; W. H. Weed, Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 717; C. R. Keyes, idem, vol. 30, 1900, p. 323; G. Giirich, Zeitschr. prakt. Geologie, 1899, p. 173; F. Beyschlag, P. Krusch, and J. n. L. Vogt, Die Lagerstatten der nutzbaren Mineralien und Gesteine, Stuttgart, 1910. An English translation of vol. 1 appeared in 1914. On pp. 147-158 there is an elaborate discussion of the relative abun- dance of the heavy metals. 626 METALLIC ORES. 627 from solutions. In short, an ore body is simply a concentration of certain compounds of certain metals effected by processes with which we are already familiar. Since, however, each metal forms its own special compounds, and exhibits reactions peculiar to itself, it is best for chemical purposes to adopt i chemical classification, with which the broad, general principles can be correlated. Each metal, there- fore, will be treated by itself as a chemical individual and from a chemical point of view. Geologically it is important to know whether an ore deposit, laid down from solution, occupies the pores of a sandstone, a limestone cavern, or a fissure in the rocks; and it is also desirable to ascertain how these cavities or crevices were formed. To the chemist these considerations are for the most part irrelevant; but the conditions under which given compounds can be dissolved or precipitated are fundamental. What are the components of ore bodies ? How were they produced ? In what way are they redistrib- uted ? These are some of the questions which the chemist is expected to answer. The details must be studied with reference to the indi- vidual metals; but some general considerations require attention first. SOURCE OF METALS. Although the immediate derivation of metallic ores if often from sedimentary rocks, the original source of the metals is to be sought in the igneous magmas . 1 In igneous rocks of some sort the metals were once diffused, and their presence in eruptive material is easily detected. G. Forchhammer 2 in a series of rock samples found traces of silver, copper, lead, bismuth, cobalt, nickel, zinc, arsenic, anti- mony, and tin, to say nothing of the commoner metals, iron and man- ganese. Some of the same elements were found in the ashes of plants, which had extracted them from the soil. From these experiments Forchhammer concluded that ore bodies derived their contents from the neighboring rocks, a conclusion at which other investigators have also arrived. In an elaborate series of researches F. Sandberger 3 found that the dark silicates of many rocks contained lead, copper, tin, antimony, arsenic, nickel, cobalt, bismuth, and silver, and upon these facts he based his famous theory of 11 lateral secretion.” That is, Sandberger concluded that metalliferous veins derived their me- tallic contents by lateral leaching from adjacent rocks. This theory, however, was subjected to much criticism by A. Stelzner, F. Po§epny, and others , 4 * * it being shown that in some instances at least the country rocks might have received secondary impregnations from the veins. 1 C. R. Keyes (Bull. Am. Inst. Min. Eng., 1910, p. 527) has suggested the possible derivation of heavy metals from meteoritic matter, especially meteoric dust. 2 Pogg. Annalen, vol. 95, p. 60. 3 Untersuchungen iiber Erzgange, Wiesbaden, 1882 and 1885. See also Neues Jahrb., 1878, p. 291, on copper, lead, cobalt, and antimony in basalt. * A. Stelzner, Zeitschr. Deutsch. geol. Gesell., vol. 31, 1879, p. 644, and rejoinder by F. Sandberger, idem, vol. 23, 1880, p. 350. F. Posepn^, Trans. Am. Inst. Min. Eng., vol. 23, 1893, pp. 247-254. 628 THE DATA OE GEOCHEMISTRY. In other investigations, some earlier and some more recent, the dis- semination of heavy metals in igneous rocks is clearly proved. A. Daubree 1 found determinable quantities of arsenic and antimony in basalt — namely, 0.01 gram of As and 0.03 of Sb to the kilogram,, The same metals, together with lead and copper, were detected by G. F. Becker 2 in the fresh granites near Steamboat Springs, Nevada. In the porphyries of Leadville, Colorado, W. F. Hillebrand 3 was able to determine lead. Out of 18 samples, taken at points distant from ore bodies, three contained no lead, the richest carried 0.0064 per cent, and the average was 0.002 per cent of PbO. One porphyry yielded 0.008 per cent of zinc oxide, and a rhyolite contained 0.0043 per cent. Silver was also found in these rocks in variable quantities, the best average giving 0.0265 ounce per ton. Gold, although some- times present in traces, was generally not found. Traces of silver in diabase and diorite are reported by G. F. Becker 4 near Washoe, Nevada, and in the quartz porphyry of Eureka J. S. Curtis 5 found both gold and silver. Silver, according to S. F. Emmons, 6 is also present in the eruptive rocks of Custer County, Colorado, and J. W. Mallet found it in volcanic ash from two points in the Andes. Ash from Cotopaxi 7 carried silver to the extent of 1 part in 83,600, and ash from Tunguragua 8 yielded 1 part in 107,200. The latter quan- tity is very near Hillebrand’ s average for the Leadville porphyries, which is equivalent to 1 part in 110,000. In recent volcanic ash from Vesuvius E. Comanducci 9 found 0.0854 per cent of copper oxide, with 0.0038 of cobalt oxide. In four rocks — granite, porphyry, and diabase from the Archean of Missouri — J. D. Robertson 10 determined the following percentages of lead, zinc, and copper: Pb, 0.00197 to 0.0068; average, 0.004. Zn, 0.00139 to 0.0176; average, 0.009. Cu, 0.00240 to 0.0104; average, 0.006. The adjacent Silurian and Carboniferous limestones also contained these metals, but in slightly smaller proportions. According to L. Dieulafait, 11 who tested hundreds of rocks, zinc and copper are always to be detected, and they are also present in sea water. Copper salts, it will be remembered, are often found 1 Compt. Rend., vol. 32, 1851, p. 827. 2 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 350. s Idem, vol. 12, 1886, pp. 591-594. « Idem, vol. 3, 1882, pp. 223-227. Assays by J. S. Curtis. & Idem, vol. 7, 1884, pp. 80-92. 6 Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 2, 1896, p. 471. Assays by L. G. Eakins. 7 Chem. News, vol. 55, 1887, p. 17. 8 Proc. Roy. Soc., vol. 47, 1890, p. 277. 9 Gazz. chim. ital., vol. 36, pt. 2, 1906, p. 797. 10 Missouri Geol. Survey, vol. 7, 1894, pp. 479-481. n Annales chim. phys., 5th ser., vol. 18, 1879, p. 349; vol. 21, 1880, p. 256. METALLIC ORES. 629 among the sublimates of Vesuvius, Stromboli, and Etna, and A. B. Lyons 1 observed copper sulphate in the crater of Kilauea. In 15 Hawaiian lavas Lyons found from 0.07 to 0.48 per cent of copper oxide; in average, 0.18 per cent. G. Steiger, however, in the labora- tory of the United States Geological Survey, analyzed a composite sample of 71 Hawaiian lavas and found only 0.0155 per cent of cop- per, showing that Lyons’s figures are doubtless much too high. A large series of igneous and metamorphic rocks of British Guiana, analyzed by J. B. Harrison, 2 also yielded appreciable quantities of copper, with sometimes other heavy metals. In 36 rocks examined 6 contained no copper, 12 contained it in traces, and one, a feldspathic tuff, carried 0.13 per cent. The average percentage of copper for the entire series was 0.025. In 23 samples lead was sought for and found in 5 of them, the maximum percentage being 0.02 per cent. Eight rocks yielded silver, from 4 to 54 grains per ton of 2,240 pounds, in average, 25.5 grains; and out of 29 rocks only 1 was free from gold. The highest gold was 43 grains per ton; the mean was 6.5 grains. Even more positive evidence as to the wide distribution of the heavy metals was obtained by F. W. Clarke and G. Steiger . 3 Large composite samples of igneous rocks, clays, and river silt were ana- lyzed, and in them copper, lead, zinc, nickel, and arsenic were deter- mined. The results obtained, in percentages, appear in the following table : Percentages of heavy metals in composite samples. A. The “red clay” of the oceanic depths. Composite of 51 samples, dredged from the sea bottom and representative of all the great oceans. The larger part of this material was collected by the Challenger Expedition. Determinations (by E. C. Sullivan) of CuO, ZnO, PbO, and AS 2 O 5 made on 150-gram portions. B. “Terrigenous clays,” from oceanic depths of 140 to 2,120 fathoms. Composite of 52 samples, namely, 4 “green muds” and 48 “blue muds,” also mainly from the Challenger Expedition. Determinations made on 300-gram portions. C. Composite of 235 samples of Mississippi silt. For the heavy metals 200-gram portions were taken. D. Composite of 329 igneous rocks, all American. Determinations on 90-gram portions. A B C D Average. NiO 0. 0320 0. 0630 0. 0170 0. 00655 0. 0296 -A.S2O5 .0010 Trace. .0004 . 00074 .0005 Pbo: .0073 .0004 .0002 . 00081 .0022 CuO .0200 .0160 .0043 . 01167 .0130 ZnO .0052 .0070 .0010 . 00638 .0049 In the foregoing pages only a part of the available evidence has been presented, but it is enough to establish the point at issue. The heavy metals are widely disseminated, both in old and in recent 1 Am. Jour. Sci., 4th ser., vol. 2, 1896, p. 424. In andesite from Lautoka, Fiji, H. I. Jensen found 0.034 per cent of copper, on an average. Chem. News, vol. 96, 1907, p. 245. The same quantity was found by R. C. Wells in a sample of the Columbia River basalt, which covers a large area. 2 Rept. on petrography of Cuyuni and Mazaruni districts, Georgetown, Demerara, 1905. On gold and silver in diabase, French Guiana, see E. D. Levat, Annales des mines, 9th ser., vol. 13, 1898, p. 386; and also in Min. Industry, vol. 7, p. 315. * Jour. Washington Acad. Sci., vol. 4, 1914, p. 58.* 630 THE DATA OF GEOCHEMISTRY. igneous rocks, from which, by proper methods, they can be concen- trated. In the laboratory of the United States Geological Survey such metals as nickel and chromium are often quantitatively esti- mated, as shown in the table on page 32. Copper is determined in exceptional cases only, but indications of its presence are fre- quently observed. Of its wide distribution in igneous rocks there is no shadow of a doubt. From the rocks all of these metals are leached, and traces of them accumulate in the sea. They also appear in many mineral springs, 1 a fact which is capable of more than one interpretation. Such a spring may derive its contents from dispersed material, or it may rise from a segregated body of ore ; its composi- tion, therefore, merely tells us that the metalliferous compounds are more or less freely soluble. The true origin of the latter is not thereby explained. That sulphides of the heavy metals can be dissolved in or decom- posed by water alone, there is some experimental evidence. P. De Clermont and J. Frommel 2 found that sulphides of iron, nickel, cobalt, antimony, arsenic, silver, and tin were attacked by boiling water, hydrogen sulphide being given off. Some were acted upon even at temperatures below 100°; As 2 S 3 at 22°, FeS at 56°, Ag 2 S at 89°, and Sb 2 S 3 at 95°. The sulphides of copper, zinc, mercury, cad- mium, gold, platinum, and molybdenum, treated in the same way, gave no evidence of decomposition. C. Doelter’s experiments 3 were conducted differently. The natural sulphides, in fine powder, were heated with water in glass tubes to 80° during periods of 30 to 32 days. In a second series of experiments lasting 24 days, a solution of sodium sulphide was used instead of water. The following percentages of material passed into solution: Material dissolved from natural sulphides in water and in sodium sulphide solution. Water alone. With sodium sulphide. Galena 1. 79 2.3 Stibnite 5. 01 All Pyrite 2. 99 10. 6 Blende .025 . 62 Chalcopyrite . 1669 . 11 Bournonite 2. 075 3. 9 Arsenopyr ite 1.5 3.2 In most of these experiments, but not in all, the dissolved substance had the same composition as the original material. That is, the minerals dissolved as such, without decomposition — a conclusion that 1 See ante, p. 188, for examples. The traces of heavy metals which spring waters contain are often more easily detected in their sediments: that is, they become concentrated in the insoluble precipitates that spring waters often deposit. 2 Annales chim. phys., 5th ser., vol. 18, 1879, p. 189. 8 Min. pet. Mitt., vol. 11, 1890, p. 319. Research continued by Q. A. Binder, idem, vol. 12, 1891, p. 332. METALLIC ORES. 631 was strengthened by the observation that in most cases new crystal- lizations were formed. 1 According to Doelter, then, sulphides may be dissolved and recrys- tallized from water alone. This is important, but not a complete indication of what occurs in nature. Natural waters, as we well know, are not pure, but charged with various dissolved salts, which exert a varying influence upon the solution of sulphides. They also contain carbonic acid, and sometimes also the stronger mineral acids; and surface waters carry dissolved oxygen. All of these impurities take part in the solution, concentration, and redistribu- tion of metallic ores, and their effects are furthermore varied by differences of temperature. A hot water, rising from great depths and free from oxygen, produces one set of changes; a cold surface water, highly oxygenated, acts quite differently. Direct solution of ores is more likely to occur in the one case, oxidation to soluble salts is commonly evident in the other. The main fact, that solution is effected in one way or another, is well illustrated, not only by the composition of mineral springs, but also by the analyses of mine waters. For example, in a water from a mine shaft near Broken Hill, J. C. H. Mingaye 2 found, in grains per gallon, 8.40 copper, 10.67 zinc, 21.82 cobalt, and 6.71 nickel. The water was strongly acid. Two analyses of mine waters from the Comstock lode, cited by J. A. Reid, 3 are accompanied by assays for gold and silver. The more concentrated of these waters contained 188.09 milligrams per ton of water in silver, with 4.15 milligrams in gold. This water was also strongly acid. An extraordinary water from a mine tunnel at Idaho Springs, Colo- rado, analyzed by R. C. Wells in the laboratory of the United States Geological Survey, contained nearly 8 grams per liter of an oxide of molybdenum, probably the so-called soluble molybdenum blue. The water also contained a large amount of free sulphuric acid, and was a dark greenish blue in color and only transparent in very thin layers. The molybdic compound formed about 25 per cent of the total impurity. Other typical mine waters are represented in the fol- lowing table of analyses, which, when not otherwise stated, were made in the laboratory of the United States Geological Survey. All are reduced to the uniform ionic standard and to parts per million. 4 1 Still more recently O. Weigel (Nachrichten K. Gesell. Gottingen, Math.-phys. Klasse, 1906, p. 525) has determined the solubility in pure water of the sulphides of Pb, Hg, Ag, Cu, Cd, Zn, Ni, Co, Fe, Mn, Sn, As, Sb, and Bi. All were slightly soluble. For an abridgment of this paper, see Zeitschr. physikal. Chemie, vol. 58, 1907, p. 293. 2 Records Geol. Survey New South Wales, vol. 8, 1909, p. 292. 3 Bull. Dept. Geology Univ. California, vol. 4, pp. 189, 192. In the same volume, p. 332, A. C. Lawson gives an analysis of water from the Ruth mine, Robinson district, Nevada. < For other analyses of minewaters, see J. A. Phillips, Philos. Mag., 4th ser., vol. 42, 1871, p. 401; A.Schrauf, Jahrb. K.-k. geol. Reichsanstalt, vol. 41, 1891, p. 35; A. C. Lane, Proc. Lake Superior Min. Inst., vol. 12, 1906, p. 97; W. H. Emmons and G. L. Harrington, Econ. Geology, vol. 8, p. 653, 1913; W. J. Sharwood, idem, vol. 6, p. 742, 1911; C. R. Van Hise and C. K. Leith, Mon. U. S. Geol. Survey, vol. 52 pp. 543, 579, 1911; J. S. Maclaurin, 45th Ann. Rept. Dominion Laboratory, New Zealand, 1912, pp. 47, 48. A few others have already been cited in the chapter on mineral springs. F. Posepn^ (Trans. Am. Inst. Min. Eng., vol. 23, 1893, p. 240) has tabulated the occurrences of Sn, Sb, Cu, and As in mineral waters. 632 THE DATA OF GEOCHEMISTRY. Analyses of mine waters. A. Water from 500-foot level of Geyser mine, Custer County, Colorado. B. Same locality as A, from the 2,000-foot level. Contains also traces of Br, I, F, and B4O7. Analyses A and B by W. F. Hillebrand. Discussed by S. F. Emmons, Seventeenth Ann. Kept. U. S. Geol. Survey, pt. 2, 1896, p. 462. C. Water from the Stanley mine, Idaho Springs, Colorado. Analyses by L. J. W. Jones, Proc. Colorado Sci. Soc., vol. 6, 1897, p. 48. D. Hot water from a bore hole 2,316 feet deep, in the Mizpah mine, Tonopah, Nevada. Analysis by R. C. Wells. Bicarbonates here reduced to normal carbonates. E. Water from St. Lawrence mine, Butte, Montana. Analysis by Hillebrand. F. Water from Mountain View mine, Butte, Montana. Analysis by Hillebrand. Contains a trace of arsenic. G. Water from Alabama Coon mine, Joplin district, Missouri. Analysis by H. N. Stokes. H. Water from the Victor mine, Joplin district. Analysis by H. A. Buehler and V. A. Gottschalk, Econ. Geology, vol. 5, 1910, p. 28. The authors also give three other analyses of Joplin mine waters. Their study relates to the oxidation of sulphide ores, and they find that pyrite or marcasite accelerates the reac- tivity of other sulphides. Two more analyses of zinc-bearing mine waters from the Joplin district are reported by C. P. Williams, Am. Chemist, vol. 7, 1877, p. 286. See also E. S. H. Bailey, Water-Supply Paper U. S. Geol. Survey. No. 273, 1911, p. 349. I. Water from the Burra Burra mine, Ducktown, Tennessee. One of a series of six analyses of mine waters by R. C. Wells. J. Water from the Rothschonberger Stolln, Freiberg, Saxony, at its point of discharge into the Triebisch Valley. Analysis by Frenzel. Described by H. Muller, Jahrb. Berg-u. Huttenw. Konig. Sachsen, 1885, p. 185. Discharges 479 kilograms of ZnO daily, or 175,024 kilograms per annum. Cl... so 4 .. C03-. N0 3 .. P0 4 .. K.... Na... Li... Ca... Sr... Mg... Al... Fe w . Fe".. Mn. . Ni... Co... Cu... Zn... Cd... Pb... Sn... Si0 2 . Total COr 7.9 43.2 110. 5 10. 6 36.4 Trace. 37.4 12. 25 a. 4 . 7 .8 Trace. .2 Trace. 25. 9 286. 25 186. 40 161. 70 1, 513. 44 1. 60 Trace. 198. 00 719. 45 2. 85 146. 41 1. 95 177. 67 1. 06 [ 3.50 .57 .02 .34 1. 35 24.42 3, 140. 73 2, 528. 46 8. 16 2, 039. 51 70. 00 106. 27 187. 15 93. 50 3. 12 164. 82 3. 44 155. 58 77. 05 49. 66 43. 80 3, 002. 06 35.6 327.2 87. 9 Trace. 3.4 148.8 68.8 6.3 .7 .7 Trace. 64.8 13.0 2, 672. 0 Trace. 13. 1 39.6 132.5 61.6 83.5 159.8 12.0 .5 59.1 852.0 41.1 17.0 47.7 744.2 121.2 4, 204. 5 23.7 a AI2O3+P2O5, 0.8 per million. METALLIC OKES. 633 Analyses of mine waters — Continued. F G H I J Cl 17. 7 71, 053. 3 1.5 6.8 41. 7 Trace. 307. 7 149.2 85.2 2.7 6, 153. 2 3. 65 1, 647. 58 0.1 6 , 664. 0 12.4 124.8 so 4 PCL K , 4 . 5 49. 9 None. 345.3 25.2 142. 1 } 474 . 6 1. 7 3. 20 13. 02 19. 8 23.4 Na Li Ca 260. 45 48. 60 11. 70 67.6 40.6 433.0 None. 2, 178. 0 .2 46.4 14.5 Mg A1 Fe 7// . } 6.6 Fe" 49.8 13.2 3.5 4. 6 45, 633. 2 411.2 142. 80 Mn Ni Co Cu 3.7 2, 412. 0 9.0 107.6 312.1 199.8 Zn 345. 10 8.9 Cd Si0 2 67.4 23. 20 251. 70 55. 6 129.6 18.0 H 2 SO 4 , free Total C0 2 117, 846. 0 8.9 9, 727. 5 2, 751. 00 87.0 10, 123. 8 <*231. 6 o244.9 in the original. Analysis A represents vadose or superficial water; B, water from the deep circulation. The difference in concentration is remarkable. Water F is essentially a strong solution of copper sulphate, formed by oxidation of sulphides. Such waters are common in copper mines, and from them the copper can in many cases be profitably recovered. The Ducktown water is also noteworthy on account of its high pro- portion of ferrous sulphate . 1 The phenomena of solution, then, are evidently of supreme impor- tance in the concentration of metallic ores. This statement can be given the broadest possible construction. A magmatic ore owes its segregation to a relative insolubihty in the magma. A residual or detrital ore is formed, at least in part, by the removal from a rock of the more soluble constituents, the less soluble thereby becoming concentrated. Sedimentary ores are deposited from solutions, either directly or by precipitation, and metalliferous veins represent an- other aspect of the same processes. The original magmatic rocks are separated, by solution or leaching, into different fractions; and then, by direct deposition, by precipitative reactions, or by metaso- matic replacements, ore bodies, and especially vein fillings, are formed. In most cases, probably, the final, workable deposit is the outcome of a series of concentrations, the result of several interdependent proc- esses, but the underlying principles are the same. By differences of solubility, the constituents of the earth’s crust are separated from one For the remarkable calcium chloride waters of the Lake Superior copper region, see ante, p. 185. 634 THE DATA OF GEOCHEMISTRY. another, to be laid down again under different conditions and in different places. The two fundamental facts with which we now have to deal are the dissemination of the heavy metals in the igneous rocks and the circulation of the underground waters. Descending, meteoric waters effect some of the observed concentrations; lateral secretions bring ' about others, and waters ascending from unknown depths play their part in the complex of phenomena. Whether these waters have a common origin or not is unessential to the present discussion. It is held by some writers, notably by Suess, that certain of the ascending waters arise from the original magma and now see the light of day for the first time. This conception has been correlated with the notion that the heavier metals, by virtue of their high specific gravity, are concentrated at great depths, from which the solvent waters bring them to the surface . 1 Speculations of this sort are interesting, but not necessary for present purposes. The fact that the ascending, deep-seated waters are hot, and therefore more powerful as agents of solution, is, however, most pertinent. The general principles governing the circulation of the under- ground waters have been elaborately discussed by Van Hise , 2 and need not be especially considered here. The arguments are mainly physical and geological, and have only partial relation to chemistry. These waters, ascending, descending, or lateral secreting, tend to gather into trunk channels, in which, sooner or later, some of the substances held in solution are deposited. Ore bodies are thus formed, but only in exceptional cases. By far the greater number of veins are barren of heavy metals, or at least so nearly barren that they need not be further described. Once in a while concentrations of heavy metals are produced, and in most cases, but not invariably, they appear in association with rock of igneous origin . 3 This asso- ciation seems to be fundamentally important, so far as the metal- liferous veins are concerned, and the problem of their origin is the only one now before us. Magmatic, sedimentary, and detrital ores fall under other headings. An igneous effusion forces its way to the surface of the earth, thereby displacing and fracturing the rocks which were in its path. As it cools and shrinks, other crevices are formed, through which 1 See L. De Launay, Contribution k l’fetude des gites mfetallif feres, 1897, p. 6; and F. Posepn^, Trans. Am. Inst. Min. Eng., vol. 23, 1893, p. 206. J. H. L. Vogt (Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 125) and also C. R. Van Hise (A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904) dissent from this view. The importance of magmatic waters as vein fillers has been recently argued by A. C. Spencer, Trans. Am. Inst. Min. Eng., vol. 36, 1906, p. 364. The magmatic waters are regarded by J. E . Spurr (Econ. Geology, vol. 2, 1907, p. 781) as residues representing the last stage of magmatic differentiation; and in them the heavier metals and other vein-filling materials are supposed to be concentrated. 2 A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, chapter 12. * See Beck’s work on ore deposits. Also papers by J. F. Kemp, Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 169; vol. 33, 1903, p. 699; J. E. Spurr, idem, vol. 33, 1903, p. 288; W. H. Weed, idem, vol. 33, 1903, p. 715; W. Lindgren, idem, vol. 30, 1900, p. 578. METALLIC ORES. 635 also the mineralized waters can find a passage. These waters may be partly magmatic, brought with the igneous matter from the depths, or partly gathered from sedimentary material; but whatever may have been their source, they are heated, and therefore their solvent power is increased. During solidification, moreover, any water that was entangled within the molten rock is extruded, carry- ing its dissolved load into the open channels. A blend of waters from different sources — deep seated, superficial, and magmatic — enters the crevices of the rocks, each part of the mixture contributing its share to their filling. The solutions thus commingled are, more- over, not all alike, and therefore chemical reactions, such as double decompositions and precipitations, become possible between them. The frequent concentrations of ores at points of intersection between two veins may possibly indicate reactions of this kind. These changes are also complicated by reactions between intruded rock and the formations which it has penetrated, and they vary with varia- tions in the latter. Some ore deposits are . evidently produced in zones of contact metamorphism, especially in limestones, and the ores are then associated with such characteristic minerals as garnet, wol- lastonite, pyroxene, vesuvianite, and so on . 1 Aqueous solutions take part in some of these changes, penetrating the walls of the contact and bringing about metasomatic replacements . 2 In the ascent of an igneous intrusion, with its entangled waters, the so-called pneumatolytic processes appear to have some importance. The molten magma contains gases and vapors other than the vapor of water, as we know from the phenomena of volcanism. Whether these gases are occluded, or evolved by reactions within the magma, is not material to the present discussion. In volcanic craters they form sublimates containing copper, iron, and other heavy metals, which often consist of chlorides. Ammonium chloride, fluorine compounds, and boric acid, which last is volatile in steam, are other common sub- stances in volcanic emanations. In ore formation the magmatic chlorides and fluorides probably have definite functions. In the molten rock they convert some part of the heavy metals into compounds which are volatile at high tem- peratures and which therefore tend to gather at the margins of the intrusions. There, being soluble in water, they pass into solution, and so find their way into the open channels wherein deposition takes place. With them other substances are deposited, forming the gangue minerals — calcite, quartz, barite, fluorite, etc. — in even larger amounts. 1 See W. Lindgren, Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 226. 2 Lindgren, idem, vol. 30, 1900, p. 578. These contact deposits and metasomatic alterations are fully described by Lindgren, who gives excellent summaries of the earlier literature. Later papers by Lindgren on ore deposits are in Econ. Geology, vol. 2, 1907, pp. 105, 743. 636 THE DATA OF GEOCHEMISTRY. The heavy metals, however, are not laid down as chlorides or fluor- ides except in rare instances ; hut in other forms chlorine and fluorine have acted as primary agents in bringing about their concentration, water tends to hydrolyze the salts thus formed, other solutions react with them, and quite different compounds are precipitated. In the case of tin the oxide is commonly produced; the other metals tend to appear as sulphides. Chlorine and fluorine act only as tem- porary carriers of the metals, and when their work is done they enter into other combinations. Fluorine remains in a gangue mineral, fluorspar; the chlorine returns into circulation as a soluble alkaline chloride; that is, as common salt. I ci.te only the simplest cases. The pneumatolytic process thus outlined is largely inferential and may not be entitled to much weight. Neither is it exclusive. We know that certain sulphides are magmatic minerals, and we have seen that they can be either dissolved or decomposed by heated waters. In the depths they would pass into solution with some evolution of hydrogen sulphide, as shown by the experiments of De Clermont and Frommel and in the researches of Doelter. The dissolved sulphides would be redeposited by the cooling solutions, and the hydrogen sul- phide would serve as a precipitant for the chlorides or sulphates which we assume to have been otherwise formed. The phenomena must also vary as the magmatic waters happen to be alkaline or acid, solution predominating in the one case and decomposition in the other. Carbonated waters are to be regarded as intermediate waters from this point of view, which decompose sulphides at first and gen- erate actively solvent solutions that come into play later. That is, a water containing alkaline carbonates and free carbonic acid should decompose the sulphides at great depths under the conditions there existing of high temperature and pressure. Alkaline sulphide solutions would thus be formed, in which the sulphides of the heavy metals are variably soluble. In such solutions the sulphides of tin, arsenic, and antimony dissolve freely and other sulphides in very much smaller amounts. A partial separation should be thus effected, exactly as in the operations of an analytical labora- tory. These suppositions, however, need to be tested by experiment ; until that has been done, they are only tentative. We can not assume that all metalliferous veins are alike in origin, and it is therefore unwise to generalize too sweepingly about them. We may, nevertheless, imagine a typical case and follow a series of concentrations throughout its probable course, beginning with the still unconsolidated magma. But magmas are different and yield very dissimilar rocks. One is mainly feldspathic, another mainly olivine, and a third solidifies to a pyroxenite. More commonly they are complex mixtures, and in their cooling a certain amount of differ- entiation, the segregation of certain parts, takes place. METALLIC ORES. 637 In order to form an ore body the magma must probably be richer in heavy metals than is usually the case. We know that several sul- phides exist as magmatic minerals and that they are more abundant in some places than in others, varying in this respect just as the feld- spars do. In other words, the magmatic constituents are not uni- formly distributed throughout the crust of the earth. A magma, then, with more than the average proportion of sulphides, rises to the surface of the earth and cools progressively. In so doing some seg- regation of sulphides must take place, and they become thereby con- centrated at the margin of the cooling mass. The product of con- centration may itself appear as a large and distinct ore body, like the Norwegian pyrrhotites, or it may be relatively trivial; but in either case a first step has been taken. Upon this primary concentration the circulating waters may act, and indeed have been acting from the instant that cooling began. Obviously, the waters which first operate are either those which were occluded in or generated from the rising magma or which it encoun- tered earliest in the course of its upward movement. These, there- fore, are ascending waters, whatever their previous history may have been. Their condition at first is that of highly superheated and compressed steam, for they are above the critical temperature of water and can not liquefy until they have partly cooled. Below 365° they become possibly liquid and heavily charged with matter dissolved from the magma and the adjacent rocks. Solids and gases are both dissolved, and the ascending solution, slowly cooling and mingling with other solutions as it rises, gradually deposits its burden. Its channel becomes filled with various minerals, ores, and gangues, and thus a second stage in the concentration is completed. Of this process in detail we cannot form a clear mental picture. The superheated solutions, formed at the beginning of the ascent, are something of which experience tells us very little. We know that water, at or above its critical temperature, attacks silicates vigorously, and that it will even, as shown by C. Barus, 1 form a mutual solution with glass. But how it will act with molten rock under pressure, what sort of a solution it will then develop, we do not know. It is fair to infer that the reactions will be both energetic and complex, and that supersaturated solutions are likely to be pro- duced ; but the waters which ultimately rise to the surface as thermal springs are at moderate temperatures and have lost much of their load. Furthermore, they have been modified by other waters, and reactions may have occurred of which no certain trace remains. If organic matter has reached the solutions at any point, sulphates must have undergone reduction to sulphides, and the latter com- pounds would therefore appear in more than one generation and in 1 See ante, p. 297. 638 THE DATA OF GEOCHEMISTRY. larger quantities. A multitude of different reactions are conceivably possible, and no one set can be summarized which shall cover all conditions. Surface waters, descending and then diffusing laterally, leach great areas of rock in the belt of weathering, and so reenforce the filling of the veins. Without the concurrence of waters from all directions and for long periods of time, the development of large ore bodies would be most difficult to explain. Suppose, now, that by a complex of processes, such as have been described, segregative, solvent, pneumatolytic, and precipitative, a channel has become filled with mineral matter and transformed into a vein. Suppose, also, that the vein is at first a mixture of quartz and iron pyrites, containing in moderate proportions admixtures of chalcopyrite, galena, and zinc blende, with minute but perceptible traces of silver and gold. The vein rises from the zone of anamorphism, through the belt of cementation, into the belt of weathering, where a third group of transformations, a new redistribution of material, occurs. These changes can be followed without much difficulty, and their character is partly known . 1 In the first place, the surface waters, charged with oxygen and carbonic acid, attack the outcrop of ores, oxidizing them more or less completely to sulphates. Sulphuric acid or acid salts are formed at the same time, which assist in the decomposition of the adjacent rocks. That decomposition is more than ordinarily extensive in the vicinity of metalliferous veins, and the rocks therefore acquire a higher degree of permeability to the percolating waters. The sulphates thus formed differ in solubility and are furthermore affected by other substances contained in the waters. Gold is left in the free state, in which condition it may partly dissolve in ferric solutions, but for the most part remains unchanged. Silver is con- verted into chloride, for chlorine is rarely absent in such alterative processes, and that compound dissolves with some difficulty. Part of the silver, if much silver is present, may be reduced to the metallic form and remain as native silver near the surface. The iron salts, which are ferrous at first, are soon oxidized to the ferric state, form- ing basic compounds and passing finally into hydroxide or limonite. Some iron is dissolved and carried away; in certain cases this is done completely, but generally a mass of limonite is left upon the surface, the gossan or iron cap of mining terminology. At the surface, then, there is a concentration of iron, in which a large part of the gold and possibly some silver is retained. The other metals have been washed away, more or less perfectly, and carried down to lower levels. 1 For a summary of these alterations, see R. A. F. Penrose, Jour. Geology, vol. 2, 1894, p. 288; also De Launay’s memoir, previously cited. An interesting paper by Penrose on the causes of ore shoots is in Econ. Geology, vol. 5, 1910, p. 97. METALLIC ORES. 639 The sulphates of copper and zinc are very soluble; that of lead much less so. If the descending waters contain much silica, silicates like chrysocolla and calamine are likely to be formed. If carbonates are abundant in the solutions, malachite, azurite, smithsonite, and cerusite will appear. Oxides of lead and copper may also be pro- duced, and any or all of these substances are to be found in the oxi- dized zone of an ore body. Below this zone the sulphate solutions meet the unaltered sulphides, and a secondary enrichment of them becomes possible. 1 The dominant sulphide, pyrite, reacts upon solu- tions of copper and zinc sulphates, precipitating both metals as sul- phides and passing into solution as sulphate of iron. This reaction is well known and was established experimentally. Thus at the upper portion of the unoxidized ores there is a concentration of copper, and perhaps of zinc, below which the original leaner ore continues to its limit, whatever that point may be. In this way some “ bonanzas ’ 7 originate. A separation of the metals is effected at or near the sur- face, and the more soluble ones are concentrated by reprecipitation below. Although the broad general conception of secondary enrichment is simple enough, its detailed application to specific cases is not always easy. Complex solutions are acting upon complex mixtures of minerals, and the reactions which take place are very diverse. The sulphides differ in solubility; they form with different degrees of facility; and the conditions of their precipitation vary with conditions of concentration and temperature. There are, however, several researches on record, which help to show what may happen within an established ore body. As long ago as 1837 E. F. Anthon 2 studied the precipitation of soluble metallic salts by insoluble sulphides, and a similar, but much more elaborate series of experiments was carried out much later by E. Schurmann. 3 In each investigation a series was established in which the sulphide of any one of the metals in it would be thrown down at the expense of any sulphide lower in the series. The series found by Schurmann was as follows: Palladium, mercury, silver, copper, bismuth, cadmium, antimony, tin, lead, zinc, nickel, cobalt, ferrous iron, arsenic, thallium, and manganese. For example, if a solution of copper were long in contact with the 1 On secondary enrichment, see W. H. Weed, Bull. Geol. Soc. America, vol. 11, 1899, p. 179; S. F. Em- mons, Trans. Am. Inst. Min. Eng., vol. 30, 1900, p. 177, and Weed, idem, p. 424; J. F. Kemp, Econ. Geology, vol. 1, 1905, p. 11. On enrichment by ascending waters, see Weed, Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 747. On downward enrichment, see F. L. Ransome, Econ. Geology, vol. 5, 1910, p. 205. Discus- sion by several writers of Ransome’s paper appears in the same volume, pp. 387, 477, 678. See also G. J. Bancroft, Trans. Am. Inst. Min. Eng., vol. 38, 1908, p. 245, and Bull. Am. Inst. Min. Eng., 1909, p. 581; E. S. Bastin, Econ. Geology, vol. 8, 1913, p. 51. U. S. Geol. Survey Bull. 529, 1913, by W. H. Emmons, is a general summary of the subject. So, too, is the paper by C. F. Tolman, Min. and Sci. Press, vol. 106, 1913, pp. 38, 141, 178, which closes with a long bibliography. 2 Jour, prakt. Chemie, vol. 10, 1837, p. 353. 3 Liebig’s Annalen, vol. 249, 1888, p. 326. 640 THE DATA OF GEOCHEMISTRY. sulphide of any metal following it in the series, it would decom- pose the latter with precipitation of copper sulphide. Starting with galena the reaction CuS0 4 + PbS = CuS + PbS0 4 has been actually studied by R. C. Wells, 1 in the laboratory of the United States Geo- logical Survey and the anticipated result was obtained. Wells has also investigated the precipitation of sulphides in pairs, and has found that they are thrown down unequally. If to a solution con- taining iron and copper an alkaline sulphide is added in excess, both metals are completely precipitated. But if, in a neutral solution, there is a deficiency of the alkaline sulphide, all the copper is deposited before any iron is thrown down. Attempts to form double sulphides by precipitation were unsuccessful; but double sulphides such as chalcopyrite are among the most important ores. The series of precipitations studied by Schurmann is evidently somewhat analogous to the well-known electrochemical series of the chemical elements and suggests that the phenomena of secondary enrichment may be of an electrical character. The problem of elec- trical activities in ore bodies was long ago examined by R. W. Fox 2 and has since received attention from a number of other investigators, most recently by V. H. Gottschalk and H. A. Buehler 3 and R. C. Wells. 4 Gottschalk and Buehler studied especially the oxidation of sul- phides, and found that when two different minerals are immersed in the same solution one showed an increase of solubility while the other was more or less protected. They also found and measured the differences in electrical potential among the minerals studied and found that when two of them were brought in contact and moistened they formed a small battery. Such a contact, in presence of the per- colating solutions of the earth’s crust, may be an important factor in the process of oxidation of natural minerals. Gottschalk and Buehler in their experiments used as a solvent only water. Wells, however, in a similar research measured the electrical potential of his minerals in various solutions and found wide differences. From this he concludes that the nature of the solvent is of fundamental importance and that by electrical activity different minerals may be produced, depending upon the character of the solutions. Evidently the application of theory to the discussion of any specific geological problem involves variable factors and may be exceedingly complex. 1 Econ. Geology, vol. 5, 1910, p. 1. 2 Philos. Trans., 1830, pt. 2, p. 399; idem, 1835, pt. 1, p. 39; British Assoc. Adv. Sci. Rept., 1834, p. 572; idem, 1837, p. 133; Philos. Mag., 3d ser., vol. 23, 1843, pp. 457, 491. See also W. J. Henwood, Annales des Mines, 3d ser., vol. 11, 1837, p. 585; A. von Strombeck, Karsten’s Archiv, vol. 6, 1833, p. 431; F. Reich, Poggendorf’s Annalen, vol. 48, 1839, p. 287; W. Skey, Trans. New Zealand Inst., vol. 3, 1871, p. 232; C. Barus, Mon. U. S. Geol. Survey, vol. 3, 1882, pp. 309-367. s Econ. Geology, vol. 7, 1912, p. 15. An earlier paper is in vol. 5, p. 28, 1910. 4 Bull. U. S. Geol. Survey No. 548, 1914. METALLIC ORES. 641 Analogous to the process by which the sulphides of a vein may be enriched, is another process that often operates in the formation of quite different ore bodies. This process has already been noted in relation to phosphate rock, and it consists in the precipitation of dissolved substances by limestone. A metalliferous solution, con- taining any of the heavy metals, percolates through limestone, and double decomposition takes place. The heavy metals, zinc, copper, iron, manganese, etc., are precipitated, and calcium goes into solution. Reactions of this kind have been experimentally studied by several investigators. 1 The diffused metals, or rather their compounds, may be concentrated by solution and consequent removal of the remain- ing carbonate of lime. In this connection R. C. Wells 2 has inves- tigated the relative solubilities of the metallic carbonates, much as was done by Schurmann in the series of sulphides. The order found, beginning with the least soluble, was mercury, lead, copper, cad- mium, zinc, iron, nickel, manganese, silver, calcium, magnesium. Each of these carbonates, under equal conditions, would precipitate those preceding it from aqueous solution. Wells, however, is careful to point out that the application of this series to specific cases involves consideration of mass effects which may change the order of pre- cipitation. In this bare outline of what may be supposed to happen in the formation of a metalliferous deposit, details have been purposely left out of account. Their consideration naturally follows in the succeeding pages, in which the metals are studied separately. 3 GOLD . 4 Although gold is one of the scarcer elements, it is widely diffused in nature. It is found in igneous rocks, sometimes in visible particles; it accumulates in certain detrital or placer deposits; it also occurs in sedimentary and metamorphic formations, in quartz veins, and in sea water. 5 A notable amount of gold is now recovered from copper ores, during the electrolytic refining of the copper. A. Liversidge 6 found traces of gold in rock salt from several localities, in quantities of about 1 to 2 grains per ton. F. Laur, 7 in Triassic rocks taken from 1 See for example, R. Irvine and W. S. Anderson, Proc. Roy. Soc. Edinburgh, vol. 18, 1890, p. 52; W. Meigen, Ber. Naturforsch. Gesell. Freiburg, vol. 13, 1903, p. 40; vol. 15, 1905, p. 38; and inaugural disserta- tions, Freiburg, 1906, by L. Gassner and C. Mahler. 2 Bull. U. S. Geol. Survey No. 609. 3 The work of Sullivan on the precipitation of copper by shale, feldspar, etc., is noted later in the section of this chapter upon the ores of that metal. The ores of iron, manganese, and aluminum have been suffi- ciently described in the chapters upon rock-forming minerals, rock decomposition, and the sedimentary rocks. 4 For a list of the Survey publications on gold and silver see Bull. 470, 1911. 6 See ante, p. 121. 6 Jour. Chem. Soc., vol. 71, 1897, p. 298. 7 Compt. Rend., vol. 142, 1906, p. 1409. Also in Compt. Rend. Soc. ind. minerale, Sept.-Oct., 1906, 97270°— Bull. 616—16 41 642 THE DATA OF GEOCHEMISTRY. deep borings in the department of Meurthe-et-Moselle, France, found both gold and silver. The maximum amount in a sandy limestone, was 39 grams of gold and 245 of silver per metric ton, but most of the assays ran much lower. Gold has been repeatedly observed as a primary mineral in igneous or plutonic rocks. G. P. Merrill 1 reports it in a Mexican granite, embedded in quartz and feldspar. W. Moricke 2 found visible gold in a pitchstone from Chile; and O. Schiebe 3 discovered it in an olivine rock from Damara Land, South Africa. In a series of assays of rocks collected at points remote from known deposits of heavy metals, L. Wagoner 4 found the following quanti- ties, in milligrams per metric ton, of gold and silver. The samples are Californian, except when otherwise stated. Gold and silver in rocJcs from California , Nevada , etc . [Milligrams per metric ton.] Au. Ag. Granite 104 7, 660 1, 220 Do 137 Do 115 940 Syenite, Nevada 720 15, 430 5, 590 540 Granite, Nevada 1, 130 Sandstone 39 Do 24 450 Do 21 320 Basalt 26 547 Diabase 76 7, 440 212 Marble 5 Marble, Carrara 8. 63 201 In a later investigation Wagoner 5 determined gold and silver in deep sea (Atlantic Ocean) dredgings. In six samples assayed the gold ranged from 15 to 267 milligrams per metric ton, and the silver from 304 to 1,963 milligrams. These figures suggest a very general distribution of gold in rocks of all kinds. J. ft. Don , 6 however, in an extended investigation of 1 Am. Jour. Sci., 4th ser., vol. 1, 1896, p. 309. Compare W. P. Blake, Trans. Am. Inst. Min. Eng., vol. 26, 1896, p. 290. 2 Min. pet. Mitt., vol. 12, 1891, p. 195. 3 Zeitschr. Deutsch. geol. Gesell., vol. 40, 1888, p. 611. For other examples see Stelzner-Bergeat, Die Erzlagerstatten, pp. 69-70. See also J. Catharinet, Eng. and Min. Jour., vol. 79, 1905, p. 127, on gold in the pegmatite of Copper Mountain, British Columbia. R. W. Brock (idem, vol. 77, 1904, p. 511) reports gold in British Columbia porphyries. On primary gold in a Colorado granite, see J. B. Hastings, Trans. Am. Inst. Min. Eng., vol. 39, 1909, p. 97. An association of gold with sillimanite is reported by T. L. Watson; Am. Jour. Sci., 3d ser., vol. 33, 1912, p. 241. * Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 808. 5 Idem, vol. 38, 1907, p. 704. 6 Idem, vol. 27, 1897, p. 564. A. R. Andrew (Trans. Inst. Min. Met., vol. 19, 1910, p. 276) questions the trustworthiness of many such assays of country rock. He thinks that gold as an impurity in litharge accounts for most of the reported findings. METALLIC ORES. 643 the Australian gold fields, found that the deep-seated rocks contained gold only in association with pyrite. When pyrite was absent, gold was absent also. The country rocks of the vadose region, on the other hand, were generally impregnated with gold, even at a dis- tance from the auriferous reefs, and Don supposes that the metal was probably transported in solution. This point will be discussed later. Gold occurs principally in the free state or alloyed with other metals, such as silver, copper, mercury, palladium, rhodium, bis- muth, and tellurium. Leaving detrital or placer gold out of account, its chief mineral associates are quartz and pyrite. Its connection with pyrite is so intimate that some writers have argued in favor of its existence as gold sulphide, 1 but the evidence in favor of that belief is very inadequate. No unmistakable gold sulphide has yet been found as a definite mineral species, nor is it likely to form except in an environment entirely free from reducing agents. The compounds of gold are exceedingly unstable and the metal separates from them with the greatest ease. On the petrologic side gold is most commonly associated with rocks of the persilicic type, such as granite and its metamorphic derivatives. I refer now to its primary occurrences. It is not rare in association with dioritic rocks, but in rocks of subsilicic character it is exceedingly uncommon. Its very general presence in quartz veins is testimony in the same direction, and suggests the probability that gold is more soluble in silicic magmas than in those richer in bases. The auriferous quartz veins were probably formed in most instances from solutions; but J. E. Spurr 2 has argued that in some cases they are true magmatic segregations. This view was developed by Spurr in his studies of gold-bearing quartz from Alaska and Nevada, but it has been questioned by C. R. Van Hise 3 and others. The composition of native gold is variable. The purest yet found, from Mount Morgan, Queensland, according to A. Leibius, 4 assayed as high as 99.8 per cent, the remainder being mainly copper with a trace of iron. Gold commonly ranges from 88 to 95 per cent, with more or less alloy of the metals already mentioned. The following analyses well represent the character of the variations: 1 See, for example, T. W. T. Atherton, Eng. and Min. Jour., vol. 52, 1891, p. 698; and A. Williams, idem, vol. 53, 1892, p. 451. Williams cites an auriferous pyrite from Colorado which yielded no gold on amal- gamation, but from which gold was extracted by solution in ammonium sulphide. Gold sulphide is soluble in that reagent, hence the inference that it may have been present in the ore. See also a paper by W. Skey, Trans. New Zealand Inst., vol. 3, 1870, p. 216. 2 See papers in Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 288; vol. 36, 1906, p. 372. Also Econ. Geology, vol. 1, 1906, p. 369. a A treatise on metamorphism: Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 1048-1049. See also J. B. Has- tings, Trans. Am. Inst. Min. Eng., vol. 36, 1906, p. 647. Hastings regards the Silver Peak ores as deposited by ascending waters along lines of fracturing. 4 Proc. Roy. Soc. New South Wales, vol. 18, 1884, p. 37. 644 THE DATA OF GEOCHEMISTRY, Analyses of native gold. A. Gold from Persia. Analyzed by C. Catlett in the laboratory of the United States Geological Survey. B. Electrum, Montgomery County, Virginia. Analysis by S. Porcher, Chem. News, vol. 44, 1881, p. 189. C. D, E. Gold associated with native platinum, Colombia. Analyses by W. H. Seamon, Chem. News, vol. 46, 1882, p. 216. F. Amalgam, Mariposa County, California. Analysis by F. L. Sonnenschein, Zeitschr. Deutsch. geol. Gesell., vol. 6, 1854, p. 243. Specific gravity, 15.47. Near AuHg 3 . G. Palladium gold. Taguaril, Brazil. Analysis by Seamon, Chem. News, vol. 46, 1882, p. 216. See Wilm, Zeitschr. anorg. Chemie, vol. 4, 1893, p. 300, on palladium gold from the Caucasus. Also E. Hussak, Zeitschr. prakt. Geologie, 1906, p. 284, on palladium gold in Brazil. H. Maldonite, or “black gold,” Maldon, Victoria. Analysis by R. W. E. Maclvor, Chem. News, vol. 55, 1887, p. 191. An alloy near Au 2 Bi. A B C D E F G H Au 93. 24 6. 65 None. 65. 31 34. 01 .14 84. 38 13. 26 1. 85 80. 12 2. 27 15. 84 84. 01 7. 66 39. 02 91.06 Trace. 65. 12 As Cu Hs 7. 06 60. 98 8. 21 Bi 34. 88 Fe .11 .20 .34 Trace. Trace. Quartz 100. 00 100. 00 99. 49 98. 23 98. 73 100. 00 99. 27 100. 00 The tellurides 1 containing gold are also variable in composition, partly because most of them contain silver, and often other metals, which may be only impurities. Kalgoorlite and coolgardite, for ex- ample, which are tellurides of gold, silver, and mercury, are mixtures of the mercury compound, coloradoite, with other species . 2 Calaverite and krennerite approximate to gold telluride alone. Sylvanite, pet- zite, muthmannite, and goldschmidtite are tellurides of gold and silver. The following analyses are sufficient to indicate the compo- sition of the more important of these minerals : 1 For a general review of the tellurides, with references to literature, see J. F. Kemp, Min. Industry vol. 6, 1898, p. 295. 2 L. J. Spencer, Mineralog. Mag., vol. 13, p. 268, 1903. Spencer gives a good bibliography of the Austra- lian tellurides. METALLIC ORES. 645 Analyses of tellurides containing gold. A. Calaverite, ('AuAg)Te 2 , Cripple Creek, Colorado. Analysis by W. F. Hillebrand. B. Krennerite, (AuAg)Te 2 , Nagyag, Hungary. Analysis by L. Sipocz, Zeitschr. Kryst. Min., vol. 11, 1886, p. 210. C. Sylvanite, (AuAg)Te 2 , Grand View mine, Boulder County, Colorado. Analysis by F. W. Clarke, Am. Jour. Sci., 3d ser., vol. 14, 1877, p. 286. D. Petzite, (AuAgyre, Norwegian mine, Calaveras County, California. Analysis by Hillebrand. A B c D Au 38. 95 34. 77 29. 35 25. 16 As 3. 21 5. 87 11. 74 41. 87 Cu - .34 Fe . 59 Te 57. 27 58. 60 58. 91 33. 21 Se Trace. Mo .08 Sb .65 Fe 2 0 3 . 12 Insoluble .33 99. 88 100. 82 100. 00 100. 32 There has been much discussion over the tellurides of gold. B. Brauner 1 asserts that crystalline “ poly tellurides” can be formed, which dissociate upon heating, leaving the compound Au 2 Te as an end product. Theoretically, the telluride Au 2 Te 3 should also be capable of existence. According to V. Lenher , 2 the tellurides of gold are probably not definite compounds, but more in the nature of alloys. Attempts at the synthesis of a distinct compound failed. T. K. Rose , 3 however, who studied the alloys of gold and tellurium, obtained a definite compound, AuTe 2 , identical with the natural calaverite. The same result was also obtained by G. Pellini and E. Quercigh . 4 W. J. Sharwood 5 has pointed out the very general association of bismuth with tellurium gold ores. Although gold is primarily a magmatic mineral, it is also trans- ported in and deposited from solutions. Many occurrences of gold indicate this fact very plainly. O. Dieffenbach , 6 for instance, men- tions gold incrusting siderite at Eisenberg, near Corbach, in Ger- many. O. A. Derby 7 reports films of gold on limonite, from Brazil. A. Liversidge 8 found it in recent pyrite, which formed on twigs in a hot spring near Lake Taupo, New Zealand. J. C. Newbery 9 men- tions gold in a manganiferous iron ore coating quartz pebbles, the 1 Jour. Chem. Soc., vol. 55, 1889, p. 391. 2 Jour. Am. Chem. Soc., vol. 24, 1902, p. 358. See also R. D. Hall and V. Lenher, idem, p. 919. a Trans. Inst. Min. Mot., vol. 17, 1908, p. 285. 4 Rend. R. accad. Lincei, 5th ser., vol. 19, 1910, p. 445. 5 Econ. Geology, vol. 6, 1911, p. 22. 6 Neues Jahrb., 1854, p. 324. 7 Am. Jour. Sci., 3d ser., vol. 28, 1884, p. 440. 8 Jour. Roy. Soc. New South Wales, vol. 11, 1877, p. 262. 9 Trans. Roy. Soc. Victoria, vol. 9, 1868, p. 52. 646 THE DATA OF GEOCHEMISTRY. quartz itself being free from gold. In the sinter of Steamboat Springs, Nevada, G. F. Becker 1 found both gold and silver; 3,403 grams of sinter gave 0.0034 of gold and 0.0012 of silver. Gold is also reported by J. M. Maclaren 2 in the siliceous sinter of the hot springs at Whakarewarewa, New Zealand. R. Brauns 3 has described gold as a cement joining fragments of quartz. The specimen of cinnabar from a fissure in Colusa County, California, mentioned by J. A. Phillips, 4 which was covered by a later deposit of gold, is also suggestive. According to R. W. Stone, 5 the coal of Cambria, Wy- oming, contains appreciable quantities of gold. All of these occur- rences are best interpreted on the assumption that the gold was precipitated from solution; and, indeed, they can hardly be explained otherwise. The natural solvents of gold appear to be numerous — that is, if the recorded experiments are all trustworthy. G. Bischof 6 found that gold was held in solution by potassium silicate, and Liversidge 7 was able to dissolve the metal by digesting it with either potassium or sodium silicate under a pressure of 90 pounds to the square inch. C. Doelter 8 claims that gold is perceptibly soluble in a 10 per cent sodium-carbonate solution, and also in a mixture of sodium silicate and bicarbonate. Solutions of alkaline sulphides have been found by several authorities, notably by W. Skey, 9 T. Egleston, 10 G. F. Becker, 11 and A. Liversidge, 12 to be effective solvents of gold; and Skey reports that even hydrogen sulphide attacks the metal perceptibly. All of these solvents occur in natural waters. Solutions of ferric salts are also capable, under proper conditions, of dissolving gold. According to H. Wurtz, 13 ferric sulphate and ferric chloride are both effective. P. C. Mcllhiney 14 found that the chloride acted on the metal only in presence of oxygen, which serves to render the ferric salt an efficient carrier of chlorine. Some experi- ments by H. N. Stokes 15 in the laboratory of the United States Geo- logical Survey, showed that ferric chloride and also cupric chloride dissolve gold easily at 200°. The reactions are reversible, and gold is redeposited on cooling. Ferric sulphate, according to Stokes, does i Mon. U. S. Geol. Survey, vol. 13, 1888, p. 344. * Geol. Mag., 1906, p. 511. * Chemische Mineralogie, 1896, p. 406. 4 Quart. Jour. Geol. Soc., vol. 35, 1879, p. 390. On the natural associations of gold, see F. C. Lincoln, Econ. Geology, vol. 6, 1911, p. 247. 6 BuU. U. S. Geol. Survey No. 499, 1912, p. 63. 6 Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 3, p. 843. » Proc. Roy. Soc. New South Wales, vol. 27, 1893, p. 303. 8 Min. pet. Mitt. , vol. 11, 1890, p. 328. » Trans. New Zealand Inst., vol. 3, 1870, p. 216; vol. 5, 1872, p. 382. w Trans. Am. Inst. Min. Eng., vol. 9, 1880-81, p. 639. u Am. Jour. Sci., 3d ser., vol. 33, 1887, p. 207. 12 Proc. Roy. Soc. New South Wales, vol. 27, 1893, p. 303. 13 Am. Jour. Sci., 2d ser., vol. 26, 1858, p. 51. 14 Idem, 4th ser., vol. 2, 1896, p. 293. 1 5 Econ. Geology, vol. 1, 1906, p. 650. METALLIC ORES. 647 not dissolve gold unless chlorides are also present. Perhaps the pseudomorph of gold after botryogen, a basic sulphate of iron, described by W. D. Campbell, 1 may have originated from some solu- tion in ferric salts. F. P. Dewey 2 has found that finely divided gold is perceptibly soluble in nitric acid, but that observation has little bearing upon its natural solution. W. J. McCaughey 3 has reported its solubility in hydrochloric acid solutions of iron alum and cupric chloride. With rising temperature the solubility increases rapidly. N. Awer- kiew 4 finds that gold is also dissolved by hydrochloric acid in pres- ence of organic matter. The usual laboratory solvent for gold, aqua regia, owes its efficiency to the liberation of free chlorine. T. Egleston 5 asserts that traces of nitrates with chlorides in natural waters can slowly dissolve the metal. J. R. Don 6 found that weak hydrochloric acid, 1 part in 1,250 of water, in presence of manganese dioxide, would take gold into solution. R. Pearce 7 heated gold and a solution containing 40 grains of common salt to the gallon, with a few drops of sulphuric acid and some manganese dioxide, and obtained partial solution. T. A. Rickard 8 treated a rich Cripple Creek ore, which contained manganic oxides, with a solution of ferric sulphate, sodium chloride, and a little sulphuric acid, and practically all of the gold dissolved. On immersing in this solution a fragment of black, carbonaceous shale, the gold was reprecipitated. How far solutions of this kind can be produced in nature is uncertain; but the extreme dilution of the solvents may be offset by their prolonged action. The laboratory processes all tend to accelerate the reactions. V. Lenher’s observa- tion, 9 that strong sulphuric acid, in presence of oxidizing agents, such as the dioxides of manganese and lead, dissolves gold, is probably not applicable to the discussion of natural phenomena. W. H. Emmons, 10 however, from a study of the experiments already cited, and also of the association of manganese oxides with gold in nature, has shown that the manganese plays an important part in the for- mation of auriferous deposits. Its effect is due to its interaction with acid solutions of chlorides, with which it generates chlorine; chlorine being the actual solvent of gold. In the presence of alkaline solutions, 1 Trans. New Zealand Inst., vol. 14, 1881, p. 457. Campbell’s observations need to be verified. The specimen was found in the Thames gold field, New Zealand. 2 Jour. Am. Chem. Soc., vol. 32, 1910, p. 318. 3 Idem, vol. 31, 1909, p. 1261. 4 Zeitschr. anorg. Chemie, vol. 61, 1909, p. 1. 3 Trans. Am. Inst. Min. Eng., voi. 8, 1879-80, p. 454. 6 Idem, vol. 27, 1897, p. 564. According to Don, ferric salts are not effective solvents for gold. 1 Idem, vol. 22, 1893, p. 739. 3 Idem, vol. 26, 1896, p. 978. s Jour. Am. Chem. Soc., vol. 26, 1904, p. 550. 13 Bull. Am. Inst. Min. Eng., 1910, p. 767, and Jour. Geology, vol. 19, 1911, p. 15. See also A. D. Brokaw, Jour. Geology, vol. 18, 1910, p. 321, vol. 21, 1913, p. 251. 648 THE DATA OF GEOCHEMISTRY. or of calcite, free chlorine can not appear, and the manganese oxides become inoperative. 1 The experiment by Rickard just cited is especially suggestive as illustrating the ease with which gold is redeposited from its solutions. So far as gold is concerned, the reducing agents are numberless, and many of them occur in nature. Organic matter of almost any kind will precipitate gold, and such matter is rarely, if ever, absent from the soil. Gold, therefore, although it may enter into solution, is not likely to be carried very far. On mere contact with ordinary soils it would be at once precipitated. 2 Gold is also thrown out of solution by ferrous salts, by other metals, and by many sulphides, especially by pyrite and galena. 3 According to Skey one part of pyrite will precipitate over eight parts of gold. The sulphides of copper, zinc, tin, molybdenum, mercury, silver, bis- muth, antimony, and arsenic, and several arsenides, all act in the same way. So, too, does tellurium, according to V. Lenher, 4 and also the so-called tellurides of gold. If the latter were definite com- pounds, they could hardly behave as precipitants for one of their constituent elements. SILVER . 5 Silver, like gold, is widely diffused in nature. Its presence in igneous rocks, together with gold, has been shown in the preceding pages, and its existence in sea water was noted in an earlier chapter. A. Liversidge 6 found it in rock salt, seaweed, and oyster shells, while W. N. Hartley and H. Ramage 7 discovered spectroscopic traces of silver in a large number of minerals. Out of 92 iron ores of all classes only four were free from silver, and it was generally detected in manganese ores and bauxite. Blende, galena, and the pyritic ores almost invariably contain it. Argentiferous galena, silver-lead ore, is one of the chief sources of this metal. Unlike gold, silver occurs not only native, but in many compounds. The sulphides, sulphosalts, and halogen compounds are best known; but selenides, tellurides, arsenides, antimonides, and bismuthides also exist. These minerals or groups of minerals are best considered separately. 1 See F. T. Eddingfield, Philippine Jour. Sci., vol. 8A, 1913, p. 125. Econ. Geology, vol. 8, 1913, p. 498. 2 On the relations of vegetation to the deposition of gold see E. E. Lunqwitz, Zeitschr. prakt. Geologie, 1900, pp. 71, 213. 8 See C. Wilkinson, Trans. Roy. Soc. Victoria, vol. 8, 1866, p. 11; W. Skey, Trans. New Zealand Inst., vol. 3, 1870, p. 225; vol. 5, 1872, pp. 370, 382; A. Liversidge, Proc. Roy. Soc. New South Wales, vol. 27, 1893, p. 303; C. Palmer and E. S. Bastin, Econ. Geology, vol. 8, 1913, p. 140; F. F. Grout, idem, p. 407. * Jour. Am. Chem. Soc., vol. 24, 1907, p. 355. See also R. I). Hall and V. Lenher, idem, p. 919. Later papers by Lenher are in Econ. Geology, vol. 7, 1912, p. 744; vol. 9, 1914, p. 523. On the relations of colloidal gold to ore deposition, see Bastin, Jour. Washington Acad. Sci., vol. 5, p. 64, 1915. 6 For a list of the Survey publications on gold and silver see Bull. U. S. Geol. Survey No. 470, 1911. 6 Jour. Chem. Soc., vol. 71, 1897, p. 298. i Idem, vol. 71, 1897, p. 533. METALLIC ORES. 049 Native silver, like native gold, is rarely if ever pure. It commonly contains admixtures of gold, copper, and other metals in extremely variable proportions. Silver amalgam, for instance, ranges from 27.5 to 95.8 per cent of silver, with from 72.5 to 3.6 per cent of mercury. In the Lake Superior copper mines silver is often embedded in native copper, each metal being nearly pure. Specimens showing this association are locally known as “half-breeds.” In most cases native silver is a secondary mineral. It is often found in gossan, and R. Beck 1 mentions films of silver upon the scales of fossil fishes from the Mansfield copper shales. According to J. H. L. Vogt 2 the native silver of Kongsberg is largely formed by reduction from argentite, although a derivation from proustite may also be observed. The silver thus formed is commonly filiform. 3 In a subordinate degree crystallized silver appears as a primary deposit from solutions. Vogt regards a solution of silver carbonate or bicar- bonate as the source of the metal, probably because of its association with calcite, and thinks that ferrous compounds or carbonaceous sub- stances are the precipitants. The reduction of silver and its complete precipitation in the metal- lic state by organic matter was long ago observed by H.de Senar- mont. 4 T. A. Rickard 5 also found that it was thrown down as a metallic coating upon a black, carbonaceous shale. The reduction of the sulphide by hydrogen is also possible, but less likely to occur under natural conditions. 6 Any reaction, however, which generated nascent hydrogen in contact with silver solutions would precipitate the metal. The nature of the silver solutions in metalliferous veins is not posi- tively known. Apart from Vogt’s suppositions, it seems probable that silver sulphate may be formed by oxidation of the sulphide. That salt, however, would almost certainly be transformed into chloride by the chlorides present in percolating waters. Silver chloride, although soluble with difficulty, is not absolutely insoluble, and very dilute solutions of it may well take part in the filling of veins. It has long been known, also, that silver is dissolved by hot solutions of ferric sulphate, a reaction which has been studied by H. N. Stokes 7 in the laboratory of the United States Geological Survey. The reac- tion, 2Ag + Fe 2 (S0 4 ) 3 = Ag 2 S0 4 + 2FeS0 4 , is reversible, and crystal- lized silver is redeposited on cooling. Stokes also found that a 1 Ore deposits, Weed’s translation, p. 371. 2 Zeitschr. prakt. Geologie, 1899, pp. 113, 177. 8 On the formation of “hair silver” see V. Kohlschiitter and E. Eydmann, Liebig’s Annalen, vol. 390, 1912, p. 340. 4 Annales chim. phys., 3d ser., vol. 32, 1851, p. 140. 6 Trans. Am. Inst. Min. Eng., vol. 26, 1896, p. 978. 8 See G. Bischof, Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 3, p. 856. Also J. Margottet, Compt. Rend., vol. 85, 1877, p. 1142. T Econ. Geology, vol. 1, 1906, p. 649. See also the experiment of H. C. Cooke relative to secondary enrich- ment in Jour. Geology, vol. 21, 1913, p. 1. 650 THE DATA OF GEOCHEMISTRY. solution of copper sulphate, at 200 °, was an effective solvent of silver, this reaction, like the other, being reversible. Pseudomorphs of cerargyrite, ruby silver, argentite, and stephanite after native silver are mentioned by Dana. 1 The natural arsenides, antimonides, and bismuthides of silver are imperfectly known. An arsenide, Ag 3 As, was described by H. Wurtz, 2 under the name huntilite. Wurtz also reported an antimonide, ani- mikite, Ag 9 Sb. Both minerals were found in the Silver Islet mine, Lake Superior. The commoner antimonide, dyscrasite, varies from Ag 3 Sb to Ag 6 Sb. 3 The bismuthide, chilenite, is perhaps Ag 6 Bi. Silver sulphide, Ag 2 S, is found in nature in two forms — the iso- metric argentite, which is a common ore, and the rare orthorhombic acanthite. It is one of the easiest of the silver compounds to prepare, and is formed whenever moist hydrogen sulphide 4 comes into con- tact with any other silver salt, or with the metal itself. As crystal- lized argentite it has been prepared in several ways. J. Durocher 5 obtained it by the action of hydrogen sulphide upon silver chloride at high temperatures. J. Margottet 6 prepared argentite by passing the vapor of sulphur over silver at a low T red heat. With selenium or tellurium vapor the corresponding selenide and telluride of silver were formed. J. B. Dumas 7 obtained the crystallized sulphide by the same process. F. ftoessler 8 crystallized argentite and the selenide from solution in molten silver, and the selenide also from fused bis- muth. C. Geitner, 9 by heating silver to 200° with a solution of sulphurous acid, obtained argentite. Silver sulphite, heated with water to the same temperature, broke down into argentite and crys- tallized silver. According to E. Weinschenk, 10 argentite is produced when silver acetate and a solution of ammonium sulphocyanate are heated together to 180° in a sealed tube. In this case the decom- position of the sulphocyanate yields hydrogen sulphide, which is the actually effective reagent. Finally, W. Spring 11 claims to have found that silver and sulphur could be forced to combine by repeated compression together of the two finely divided elements. The pres- sure employed was 6,500 atmospheres. Silver and arsenic also unite under the same conditions. Spring’s experiments, however, or at 1 System of mineralogy, 6th ed., p. 20. 2 Eng. and Min. Jour., vol. 27, 1879, pp. 55, 124. 3 The compound Ag 3 Sb appears to be the only definite antimonide of silver, 'the others are mixed crystals. See C. T. Heycock and F. H. Neville, Philos. Trans., vol. 189A, 1897, p. 25; E. Maey, Zeitschr. physikal. Chemie, vol. 50, 1904, p. 200: G. I. Petrenko, Zeitschr. anorg. Chemie, vol. 50, 1906, p. 139, and T. Liebisch, Sitzungsb. K. Akad. Wiss. Berlin, 1910, p. 365. Petrenko cites other references. 4 Dry hydrogen sulphide does hot attack silver. 6 Compt. Rend., vol. 32, 1851, p. 825. e Idem, vol. 85, 1877, p. 1142. 2 Annales chim. phys., 3d ser., vol. 55, 1859, p. 147. b Zeitschr. anorg. Chemie, vol. 9, 1895, p. 31. 9 Liebig’s Annalen, vol. 129, 1864, p. 358. i° Zeitschr. Kryst. Min., vol. 17, 1890, p. 497. u Ber. Deutsch. chem. Gesell., vol. 16, 1883, pp. 324, 1002; vol. 17, 1884, p. 1218. METALLIC ORES. 651 least his deductions from them, are of doubtful validity. Later investigations have failed to confirm them. 1 Some of these syntheses evidently have no exact parallel in nature. Probably the natural reactions are of the simplest kind. Sulphur, sulphur dioxide, or hydrogen sulphide acts either upon metallic silver or upon any of its naturally available compounds, solid or in solu- tion, and the sulphide is formed. Its crystallization, which is accel- erated by the laboratory methods, is presumably a question of time, aided by the slight solubility of the compound. The last remark, obviously, applies to many other sulphides also. The reduction of sulphate solutions by organic matter is another probable mode of generation. It has already been shown that argentite is easily reduced to sil- ver. Indeed, silver sulphide is the most readily reducible, that is, the least stable, of all the commoner sulphides. This is illustrated by its heat of formation, which is low compared with that of other sulphides. The following data, giving heats of formation from solid metal and solid sulphur, are furnished by Julius Thomsen. 2 The figures represent small calories. Heats of formation of various sulphides. PbS Cu 2 S HgS Ag 2 S 20 , 430 20 , 270 16 , 890 5 , 340 On the other hand, silver is precipitated from its solutions by pyrite, chalcopyrite, galena, and other sulphides. 3 H. N. Stokes, 4 in the laboratory of the United States Geological Survey, found that marcasite, heated with silver carbonate and potassium bicarbonate solution at 180°, precipitated silver sulphide. According to R. Schneider, 5 bismuth sulphide precipitates silver sulphide from a nitrate solution. A. Gibb and R. C. Philip, 6 also working with silver nitrate solutions, found that cuprous sulphide precipitated silver sul- phide, while copper or cuprous oxide threw down metallic silver. In a recent investigation by Chase Palmer and E. S. Bastin 7 a considerable number of sulphides were treated with dilute solutions of silver sulphate at ordinary room temperatures. Metallic silver 1 See W. Hallock, Am. Jour. Sci., 3d ser., vol. 34, 1887, p. 277; and Bull. U. S. Geol. Survey No. 64, 1890, p. 38. Also the general discussion of pressure effects by J. Johnston and L. H. Adams, Am. Jour. Sci., 4th ser., vol. 35, 1913, p. 205. 2 Thermochemische Untersuchungen, vol. 3, 1883, p. 455. 3 See W. Skey, Trans. New Zealand Inst., vol. 3, 1870, p. 225. * Econ. Geology, vol. 2, 1907, p. 16. & Jour, prakt. Chemie, 2d ser., vol. 41, 1890, p. 414. 6 Trans. Am. Inst. Min. Eng., vol. 36, 1906, p. 667. 7 Econ. Geology, vol. 8, 1913, p. 140. Also Palmer, idem, vol. 9, 1914, p. 664, and F. F. Grout, idem, vol. 8, p. 407. On the precipitation of silver by copper sulphides, see E. Posnjak, Jour. Am. Chem. Soc., vol. 36, 1914, p. 2475. 652 THE DATA OF GEOCHEMISTRY. was precipitated by chalcocite, niccolite, covellite(?), bornite, ten- nantite, alabandite, smaltite, marcasite, pyrrhotite, and chalcopyrite. Little or no reaction was observed with cinnabar, stibnite, pyrite, galena, millerite, sphalerite, jamesonite, orpiment, and realgar. A specimen of niccolite containing much cobaltite gave peculiarly suggestive results. The niccolite went completely into solution, precipitating an equivalent amount of silver, while the cobaltite was unattacked. The arsenides generally were found to dissolve, while the sulpharsenides, like cobaltite and arsenopyrite, failed to react. A quantitative method for estimating the relative proportions of such minerals in a mixture is therefore now available, apart from the significance of the data in the study of secondary enrichment. In certain details the results obtained are apparently inconsistent with the statements of previous investigators. This inconsistency is prob- ably due to differences in the experimental conditions. Different solutions, whether acid or alkaline, different concentrations and temperatures, and impurities in the minerals studied would account for much discordance. Pyrite, for example, often contains admix- tures of maroasite, the latter being an active precipitant of silver, the former not. Such impure pyrite would evidently give an appar- ently abnormal reaction. The case of covellite is similarly question- able. The natural mineral contains some admixed chalcocite, which precipitates silver quantitatively. Pure cupric sulphide dissolves in a solution of silver sulphate, precipitating silver sulphide. It is desirable that reactions of this class should be further investigated with pure synthetic minerals, and also with solutions of silver chloride. The nitrate is not an appropriate solvent to use, for it probably does not occur in nature, and it may give rise to confusing secondary reactions. Primary reactions of the character described in the preceding paragraphs doubtless assist in the secondary enrich- ment of ore bodies, the silver being dissolved above and redeposited below. The selenide of silver, naumannite, Ag 2 Se, is a well-known but rare mineral. A sulphoselenide, aguilarite, Ag 4 SSe, has also been de- scribed. Naumannite often contains lead, due to admixtures of the lead selenide. Hessite is the normal telluride of silver, Ag 2 Te. Stutzite, Ag 4 Te, is a more doubtful substance. The synthesis of hessite by Margottet has already been mentioned. B. Brauner 1 also obtained it by the same method. B. D. Hall and V. Lenher 2 prepared the compound by reducing silver tellurite, and they also found that a telluride was pre- cipitated by the action of tellurium upon silver solutions. Two tel- 1 Jour. Chem. Soc., vol. 55, 1889, p. 388. 2 Jour. Am. Chem. Soc., vol. 24, 1902, p. 919. METALLIC ORES. 653 lurides, AgTe and Ag 2 Te have been prepared by G. Pellini and E. Quercigh. 1 Eucairite, CuAgSe; stromeyerite, CnAgS; sternbergite, AgFe 2 S 3 ; and frieseite, Ag 2 Fe 5 S 8 , are rare silver-bearing minerals. The sulphosalts formed by silver with the sulphides of arsenic, anti- mony, and bismuth are quite numerous. Some of them are important ores; others are mineralogical rarities; but, on account of their inter- relationships, all are significant. They may be arranged as follows: Smithite Monoclinic. Miargyrite AgSbS 2 Monoclinic. Matildite AgBiS 2 (?) Proustite Ag 3 AsS 3 Rhombohedral. Xanthoconite Ag 3 AsS 3 Monoclinic. Pyrargyrite 2 Ag 3 SbS 3 Rhombohedral. Pyrostilpnite Ag 3 SbS 3 Monoclinic. Tapalpite 3 Ag 3 BiTe 3 Stephanite Ag 5 SbS 4 Orthorhombic. Pearceite Ag 9 AsS 6 Monoclinic. Polybasite Ag 9 SbS 6 Orthorhombic. Polyargyrite Isometric. Schapbachite. . . . Orthorhombic. Brongniardite Ag 2 PbSb 2 S 5 Isometric. Andorite AgPbSb 3 S 6 Orthorhombic. Schirmerite Massive. Diaphorite (Ag 2 ,Pb) 5 Sb 4 S n Orthorhombic. Freieslebenite .... (Ag 2 ,Pb) 5 Sb 4 S n Monoclinic. Several other sulphosalts of lead and copper also contain replace- ments of silver of considerable importance. Tennantite, Cu 8 As 2 S 7 , contains up to 13.65 per cent of silver; and tetrahedrite, Cu 8 Sb 2 S 7 , up to 31.3 per cent. In cosalite, Pb 2 Bi 2 S 5 , as much as 15.66 per cent of silver has been found. The tin and germanium sulphosalts, canfield- ite, Ag 8 SnS 6 , and argyrodite, Ag 8 GeS 6 , are very rare minerals. Small admixtures of any of these compounds with other sulphides, how- ever, would render the latter useful ores of silver. Several of these sulphosalts have been prepared synthetically. J. Durocher 4 claims to have obtained them by heating mixed chlorides of silver and antimony, or silver and arsenic, in a current of hydrogen sulphide. Details are not given. H. de Senarmont, 5 6 by heating a salt of silver at temperatures ranging from 250° to 350° with a solu- tion of an alkaline sulpharsenite or sulphantimonite in an excess of sodium bicarbonate, succeeded in producing pyrargyrite and prous- tite. By precipitating a solution of silver nitrate with the potassium 1 Atti R. accad. Lincei, vol. 19, pt. 2, 1910, p. 415. 2 A manganiferous sulphantimonide of silver, samsonite, allied to pyrargyrite, has been described by Werner and Fraatz, Centralbl. Min., Geol. u. Pal., 1910, p. 331. 8 Contains some sulphur partly replacing tellurium. * Compt. Rend., vol. 32, 1851, p. 825. 6 Annales chim. phys., 3d ser., vol. 32, 1851, pp. 171-173. 654 THE DATA OF GEOCHEMISTRY. sulphantimonate, K 3 SbS 3 , I. Pouget 1 obtained the amorphous com- pound Ag 3 SbS 3 , equivalent in composition to pyrargyrite. C. Doelter 2 prepared miargyrite, pyrargyrite, and stephanite by a modification of Senarmont’s method. Silver chloride, mixed with a sodium carbonate solution of potassium sulphantimonate in varying proportions, was heated with hydrogen sulphide in sealed tubes to 80°-150°. Pyrargyrite was most easily formed; miargyrite appeared only once. Doelter 3 also heated silver chloride with antimony trichloride, sulphide, or oxide in hydrogen sulphide, and obtained similar results. H. Sommerlad 4 prepared pyrargyrite, miargyrite, and stephanite by heating antimony sulphide and silver chloride together. With arsenic trisulphide, proustite was formed. The same species, and also polyargyrite, were produced when the com- ponent sulphides were fused together in a stream of hydrogen sul- phide. According to R. Schneider, 5 potassium bismuth sulphide, KBiS 2 , added to a solution of silver nitrate, precipitates the compound AgBiS 2 . This, crystallized by fusion, becomes matildite. Matildite was also made by Roessler 6 when the sulphides of silver and bismuth were allowed to crystallize together from solution in molten bismuth. F. M. Jaeger and H. S. van Klooster, 7 by prolonged heating at 200°-240° of a mixture of antimony trichloride and silver sulphide in a concentrated solution of sodium sulphide and sodium bicarbonate, obtained crystalline scales of pyrargyrite. By direct fusion of the component sulphides together in an atmosphere of nitrogen they pre- pared pyrargyrite, miargyrite, proustite and “arsenomiargyrite,” the last named being probably identical with smithite. From the fusion diagrams they infer that some of Sommerlad’s results were erroneous. From these syntheses it is evident that the sulphosalts of silver are easily formed, and by various methods. Those which involve fusion are probably not operative in nature, for the ores under con- sideration are commonly associated with gangue minerals which could not be formed in that way. Quartz, calcite, fluorite, barite, etc., are vein minerals which can be deposited only from solution, and the same rule must hold for the accompanying sulphides. Solu- tions of silver, produced by oxidation of ores, probably react with great slowness upon sulphur compounds of arsenic, antimony, or bismuth; and the new minerals are produced under varying condi- tions. The nature of the primary sulphides and of the infiltrating solutions, together with conditions of concentration and temperature, determines the character of the sulphosalts to be formed. These con- 1 Compt. Rend., vol. 124, 1897, p. 1518. 2 Allgemeine chemische Mineralogie, 1890, p. 152. * Zeitschr. Kryst. Min., vol. 11, 1886, p. 29. * Zeitschr. anorg. Chemie, vol. 15, 1897, p. 173; vol. 18, 1898, p. 420. 6 Jour, prakt. Chemie, 2d ser., vol. 41, 1890, p. 414. 8 Zeitschr. anorg. Chemie, vol. 9, 1895, p. 31. 7 Idem, vol. 78, 1912, p. 245. METALLIC ORES. 655 ditions are imperfectly known, at least quantitatively, and so far as the natural phenomena are concerned; but the syntheses give hints which may aid in their future discovery. It is also possible that arsenical or antimonial solutions may react upon silver compounds, such as argentite or the chlorides, and so form sulphosalts of different kinds. The supposable reactions are many, and it is not easy to determine which ones have operated in any particular case. The haloid ores of silver remain to be mentioned. These are repre- sented by three distinct and several intermediate mineral species; the three being cerargyrite, or horn silver, AgCl; bromyrite, AgBr, and iodyrite, Agl. Emboli te is a chlorobromide; iodobromite is rep- resented by the formula 2 AgC1.2AgBr. Agl ; cuproiodargyrite is near CuAgI 2 ; and miersite is an isometric iodide of silver, the commoner iodyrite being hexagonal. 1 All these minerals are secondary, and appear for the most part in the upper levels of ore bodies. Infiltrating solutions of chlorides, bromides, or iodides act upon the oxidation products of the primary ores, and precipitate these relatively insoluble species. They are not absolutely insoluble, however, and probably crystallize very slowly from extremely dilute solutions. A form of silver chloride identical in appearance with cerargyrite was prepared by F. Kuhlmann 2 when a solution of silver nitrate was allowed to mix very gradually with aqueous hydrochloric acid. The two solutions were separated by a porous layer of asbestos, pumice, or platinum sponge, through which they slowly commingled. 3 Such a blending of solutions may take place in nature, through layers of decomposed rock substance, such as a sandy clay or a gossan. COPPER. The minerals of copper are much more numerous than those of silver, and represent a wider range of composition. No oxidized ores of silver are known, but copper is found not only as oxide, but also in silicates, sulphates, phosphates, arsenates, carbonates, a basic nitrate, and an oxychloride. The metal is easily oxidizable, and is also easily reduced; it therefore occurs both as native copper and in its many compounds. 1 Native copper is commonly, if not always, a secondary mineral, either deposited from solution or formed by the reduction of some solid compound. Pseudomorphs of copper after the oxide, cuprite, 1 See G. T. Prior and L. J. Spencer, Mineralog. Mag., vol. 13, 1902, p. 174, for a general paper on the cerargyrite group. H. B. Kosmann (Leopoldina, vol. 30,1894, pp. 193, 203) has discussed the formation of these ores from a thermochemical point of view. A mineral having the formula 20NaCl+AgCl has been called huantajayite. Recent papers on the genesis of these ores are by C. R. Keyes, Econ. Geology, vol. 2, 1907, p. 774; Bull. Am. Inst. Min. Eng., July, 1911, p. 541, and J. A. Burgess, idem, vol. 6, 1911, p. 13. 2 Compt. Rend., vol. 42, 1856, p. 374. 3 H. Debray also crystallized the chloride, bromide, and iodide of silver from aqueous solutions in mer- curic nitrate, Compt. Rend., vol. 70, 1870, p. 995. This process can hardly be a reproduction of natural conditions, 656 THE DATA OF GEOCHEMISTRY. are well known; and remarkably perfect pseudomorphs after azurite, from Grant County, New Mexico, have been described by W. S. Yeates. 1 According to W. Lindgren, 2 a vein of metallic copper at Clifton, Arizona, appears to have been formed from chalcocite. Examples of this general character might be multiplied indefinitely. T. Carnelley 3 has shown that metallic copper is perceptibly attacked and dissolved by distilled water, and much more so by saline solutions resembling those existing in nature. The direct solubility of the sulphides was considered earlier in this chapter, and also the formation of strong sulphate solutions by oxidation of pyrite ores. From solutions such as these, but very dilute, the greater deposits of native copper appear to have been formed. In the Lake Superior region the greatest known deposits of metallic copper are found. 4 * Its original home, perhaps as sulphide, was in the unaltered igneous rocks, but its concentrations are now found in the sandstones, conglomerates, and amygdaloids. In the sand- stones and conglomerates it acts as a cement, and it also replaces pebbles and even bowlders a foot or more in diameter. Some of the masses of copper are enormous; one, for example, found in the Min- nesota mine in 1857, weighed about 420 tons. It is associated with other minerals of hydrous origin, such as epidote, datolite, calcite, and zeolites, and calcite crystals are known which had been coated with copper, and then overgrown with more calcite. Lane also men- tions a quartz crystal which had been corroded and mainly replaced by copper. Frequently the copper incloses nodules of native silver, which were evidently precipitated first and then enveloped by the baser metal. Had these metals been deposited from a fused magma they would have formed, not separately, but as an alloy. The reducing agent, according to Pumpelly, was probably some compound of iron, oxide or silicate; and R. D. Irving substantiates this opinion by citing particles of cementing copper which inclosed cores of magnetite. Pumpelly’s conclusion was based upon the constant asso- ciation of the Lake Superior copper with epidote, delessite, and the green earth silicates, all of which are ferriferous. H. N. Stokes 6 has found that hornblende and siderite can precipitate metallic cop- per from a sulphate solution heated to 200°. Under certain condi- tions, also, ferrous sulphate, pyrite, and chalcocite are capable, accord- 1 Am. Jour. Sci., 3d ser., vol. 38, 1889, p. 405. 2 Prof. Paper U. S. Geol. Survey No. 43, 1905, p. 101. 2 Jour. Chem. Soc. , vol. 30, 1876, p. 1. See also R. Meldrum, Chem. News, vol. 78, 1898, p. 209. «See H. Credner, Neues Jahrb., 1869, p. 1; R. Pumpelly, Am. Jour. Sci., 3d ser., vol. 2, 1871, p. 348; Geol. Survey Michigan, vol. 1, pt. 2, 1873, and Proe. Am. Acad., vol. 13, 1878, p. 253; M. E. Wadsworth, Bull. Mus. Comp. Zool., vol. 7, 1880, p. 1; R. D. Irving, Mon. U. S. Geol. Survey, vol. 5, 1883, chapter 10; A. C. Lane, Rept. State Bd. Geol. Survey Michigan, 1903, p. 239; Quart. Bull. Canadian Min. Inst., No. 13, 1911, p. 81; and two volumes on the Keweenaw series, published by the Michigan Survey in 1911. In the Keweenawan rocks of Minnesota F. F. Grout (Econ. Geology, vol. 5, 1910, p. 471) has found from 0.012 to 0.029 per cent of copper. 6 Econ. Geology, vol. 1, p. 648, 1906. METALLIC ORES. 657 ing to Stokes, of reducing cupric sulphate to the metallic state. Cop- per itself reacts with cupric sulphate solutions, reducing them to cuprous form. When such a solution of cuprous sulphate is produced at a high temperature, it deposits crystallized metallic copper upon cooling. 1 In this way a hot ascending solution of cupric sulphate may dissolve copper and redeposit it at a higher, cooler level. H. C. Biddle, 2 by heating a solution of ferrous chloride, cupric chloride, and potassium bicarbonate in an atmosphere of carbon dioxide under pressure, obtained a precipitate containing metallic copper. A. Gautier 3 has shown that superheated steam will reduce cuprous sulphide, chalcocite, to the metallic state, according to the reaction — Cu 2 S + 2H 2 0 = 2Cu + S0 2 + 2H 2 . Some experiments conducted in the physical laboratory of the United States Geological Survey 4 are very suggestive as regards the crystallization of copper and silver. Water, ammonium chloride, and tremolite were heated together during three and a hah days, at 465° to 540°, in a steel bomb lined with a silver-plated copper tube. The tube was attacked near its base, and the two metals were redeposited in separate crystals in the upper and cooler regions of the apparatus. In the lower, hotter part an alloy of silver and copper was formed. In some cases organic matter is evidently the reducing agent. H. de Senarmont 5 showed that copper solutions were thus reduced at temperatures between 150° and 250°. it. Beck 6 mentions native copper filling the marrow cavities of fossil bones in the Peruvian sandstones of Corocoro, Bolivia. The films of copper often found in shales, as, for example, near Enid, Oklahoma, 7 were doubtless pre- cipitated by substances of organic origin. 8 On the other hand, copper readily undergoes oxidation, yielding cuprite, malachite, and sometimes azurite. All of these species are known to occur as coatings upon the native metal. On buried Chinese copper coins of the seventh century A. F. Rogers 9 identified 1 Stokes, Econ. Geology, vol. 1, 1906, p. 648. See also earlier investigations cited by Stokes. 2 Jour. Geology, vol. 9, 1901, p. 430; and Am. Chem. Jour., vol. 26, 1901, p. 377. G. Femekes (Econ. Geology, vol. 2, 1907, p. 581) has also described the precipitation of copper from neutral chloride solutions by FeCl 2 . See also C. F. Tolman and J. D. Clark, idem, vol. 9, 1914, p. 559, on the behavior of copper in electrolytic and colloidal solutions. 3 Compt. Rend., vol. 142, 1906, p. 1465. * Preliminary notice by F. E. Wright, Science, vol. 25, 1907, p. 389. 6 Annales chim. phys., 3d ser., vol. 32, 1851, p. 140. « Ore deposits, Weed’s translation, p. 499. i See E. Haworth and J. Bennett, Bull. Geol. Soc. America, vol. 12, 1900, p. 2. 8 The association of copper ores, other than native copper, with organic remains is by no means rare. For example, E. J. Schmitz (Trans. Am. Inst. Min. Eng., vol. 26, 1896, p. 101) mentions impregnations of copper in fossil wood in the Permian of Texas. Percy (Metallurgy, vol. 1, 1875, p. 211) refers to a cuprif- erous peat in Wales which had actually been worked as an ore. Its ash contained about 3 per cent of copper. 9 Am. Geologist, vol. 31, 1903, p. 43. Similar coins, probably from the same find, are in the collections of the United States National Museum. A. Lacroix, Bull. Soc. min., vol. 32, 1909, p. 334, has reported chalcocite on ancient Roman coins. 97270°— Bull. 616—16 42 658 THE DATA OF GEOCHEMISTRY. cuprite, malachite, azurite, cerusite, and occasional crystals of metallic copper. In the last case the oxidation had been followed by a reduction. Other similar examples are known. Among the less important ores of copper there are three arsenides, an antimonide, some selenides, and a telluride. The arsenides are domeykite, Cu 3 As; algodonite, Cu 6 As; and whitneyite, Cu 9 As. Mohawkite is a domeykite containing several per cent of cobalt and nickel. Domeykite was produced artificially by G. A. Koenig , 1 who passed the vapor of arsenic over red-hot copper. Horsfordite is the antimonide, Cu 6 Sb. Two selenides are known, namely, berzelianite, Cu 2 Se, and umangite, Cu 3 Se 2 . Crookesite is a selenide of copper, silver, and thallium, and rickardite is the telluride, Cu 4 Te 3 . In the electrolytic refining of copper at Baltimore considerable quantities of tellurium accumulate in the slimes. It was probably diffused as telluride of copper in the original ores. The sulphides of copper and its double sulphides with iron are the most important ores of this metal. Their composition is shown in the subjoined formulae: Chalcocite Cu 2 S. Covellite CuS. Chalcopyrite CuFeS 2 . Chalmersite 2 CuFe 2 S 3 . Cubanite CuFe 2 S 4 . Bornite 3 Cu 6 FeS 4 . To this list the rare cobalt copper sulphide, carrollite, CuCo 2 S 4 , may be added. Several of these species have been found as furnace products, or obtained by intentional syntheses. As a furnace product, chalcopy- rite has been several times reported; and A. N. Winchell 4 found it, together with bomite, thus formed, probably by sublimation, at Butte, Montana. On another product from the same locality, W. P. Headden 5 discovered cubanite. Chalcopyrite was first prepared by J. Fournet , 6 who simply fused pyrite and copper sulphide together. F. de Marigny 7 obtained bornite by fusing pyrite with copper turn- ings and sulphur, a process essentially identical with Fournet’s, the difference in product probably depending upon the proportions of the materials used. 1 Am. Jour. Sci., 4th ser., vol. 10, 1900, p. 439. 2 See E. Hussak, Centralbl. Min., Geol. u. Pal., 1906, p. 332. R. Schneider (Jour, prakt. Chemie, 2d ser., vol. 52, 1895, p. 555) gives the formula here assigned to chalmersite to cubanite. 3 Formula as established by B. J. Harrington, Am. Jour. Sci., 4th ser., vol. 16, 1903, p. 151. The older, commonly accepted formula is Cu 3 FeS 3 . On serial relations between the copper-iron sulphides, see E. H. Kraus and P. Goldsberry, Am. Jour. Sci., 4th ser., vol. 37, 1914, p. 539. An important preliminary paper on these ores, by L. C. Graton and J. Murdoch is in Trans. Am. Inst. Min. Eng., vol. 45, 1914, p. 26. * Am. Geologist, vol. 28, 1901, p. 244. 6 Proc. Colorado Sci. Soc., vol. 8, 1905, p. 39. « Annales des mines, 3d ser., vol. 4, 1833, p. 3. * Compt. Rend., vol. 58, 1864, p. 967. METALLIC ORES. 659 J. Durocher, 1 by the action of hydrogen sulphide upon the vapor of copper chloride, obtained copper sulphide in hexagonal tables. H. de Senarmont 2 heated a solution containing ferrous and cuprous chlorides, sodium persulphide, and a large excess of sodium bicar- bonate to 250°, and so produced an amorphous precipitate having the composition of chalcopyrite. According to C. Doelter, 3 malachite, heated with hydrogen sulphide solution to 80°-90° in a sealed tube, yields covelhte. Cupric oxide, heated to 200° in a stream of hydro- gen sulphide, was converted into covellite; at higher temperatures chalcocite formed. By gently heating a mixture corresponding to 2Cu0 + Fe 2 0 3 in gaseous hydrogen sulphide, Doelter obtained chal- copyrite; and from a mixture of cuprous, cupric, and ferric oxides in the same gas at 100° to 200° he prepared bornite. E. Weinschenk 4 effected the synthesis of both chalcocite and covellite by heating cuprous or cupric solutions with ammonium sulphocyanate to 80° in sealed tubes. It must be remembered in this connection that the sulphocyanate serves merely as a source of hydrogen sulphide under pressure. A. F. Rogers 5 obtained covellite by heating sphalerite in a solution of copper sulphate at 150°-200° in a sealed tube. At several of the French thermal springs, Bourbonne-les-Bains, Plombieres, etc., A. Daubree 6 found Roman coins and metals upon which, derived from the bronze, chalcocite, chalcopyrite, bornite, and tetrahedrite had formed. Similar observations were made by C. A. de Gouvenain 7 at Bourbon-! Archambault. E. Chuard 8 found chal- copyrite upon bronze articles from the Swiss lake dwellings. In all of these instances the copper of the bronze had been attacked by waters containing either hydrogen sulphide or alkaline sulphides. Of these sulphide ores, chalcopyrite, bornite, and chalcocite are by far the most important. Chalcopyrite and bornite are probably the primary compounds from which the others are in most cases derived, and they have been repeatedly identified as of magmatic origin. In Tuscany, according to B. Lotti, 9 pyrite, chalcopyrite, bornite, chalco- cite, and sometimes blende or galena, occur in serpentinized rocks as original segregations. Similar occurrences in Servia are reported by R. Beck and Baron W. von Fircks; 10 and in dioritic rocks at Ookiep, Namaqualand, by A. Schenck. 11 In a pegmatite near Princeton, 1 Compt. Rend., vol. 32, 1851, p. 825. 2 Annales chim. phys., 3d ser., vol. 32, 1851, p. 166. 3 Zeitschr. Kryst. Min., vol. 11, 1886, pp. 34-36. 4 Idem, vol. 17, 1890, p. 497. s School of Mines Quart., vol. 32, 1911, p. 298. e Annales des mines, 7th ser., vol. 8, 1875, p. 439; Compt. Rend., vol. 80, 1875, p. 461; Etudes synth&iques de g6ologie exp<5rimentale, pp. 72-86. See also A. Lacroix, Bull. Soc. min., vol. 32, 1909, p. 333. 7 Compt. Rend., vol. 80, 1875, p. 1297. 8 Idem, vol. 113, 1891, p. 194. 9 Bull. Soc. g6ol. Belgique, vol. 3, M&n., 1889, p. 179. Zeitschr. prakt. Geologie, 1901, p. 321. ii Zeitschr. Deutsch. geol. Gesell., vol. 53, Verhandl., 1901, p.64. See also W. H. Weed, Eng. and Min. Jour., vol. 79, 1905, p. 272. 660 THE DATA OE GEOCHEMISTRY. British Columbia, J. F. Kemp 1 found bornite, which had all the appearance of a primary mineral. To original sources of this kind, segregated or disseminated sulphides, the other concentrations of copper ores may reasonably be attributed. These minerals are found also in veins, in contact zones, and in impregnations or replacements in sedimentary rocks, but the home of the copper in the first place must have been in rocks of igneous origin. To these primitive ores the syntheses by fusion may have some relation; secondary deposi- tions originated by other methods. From chalcopyrite or bornite, commonly admixed with pyrite, the other ores of this group are generated. At a locality in the Altai Mountains, says P. Jeremeef , 2 every stage of transition from chalco- pyrite to chalcocite may be observed. In the secondary enrichment of copper ores, pyrite plays an important part. Cupric solutions, formed by oxidation of ores in the upper levels of an ore body, react upon pyrite, and chalcocite is formed. This reaction has been par- tially studied by H. V. Winchell , 3 who treated cupriferous pyrite with dilute solutions of copper sulphate and sulphur dioxide and obtained films of cuprous sulphide. The sulphides of arsenic, lead, and zinc precipitated copper sulphide from sulphate in the same way. Chalcocite is thus formed both from pyrite and zinc blende, accord- ing to W. Lindgren , 4 at Clifton and Morenci, in Arizona. Chalcocite itself alters into chalcopyrite, bornite, and covellite , 5 the last species being almost invariably of secondary origin. Covellite heated with a solution of sodium bicarbonate was found by H. N. Stokes 6 to yield chalcocite; and chalcocite reacts with copper sulphate to form both covellite and native copper. The precipitation of chalcocite by pyrite was also verified by Stokes . 7 In short, these minerals are quite generally convertible one into another by very varied reactions, and their paragenesis, therefore, must be studied independently for each deposit in which they occur . 8 No simple rules can be formed to cover all cases, and a part of the difficulty arises from the fact that many of the reactions are reversible. 1 Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 182. See also J. Catherinet, Eng. and Min. Jour., vol. 79, 1905, p. 125. Primary bornite and chalcopyrite in a dioriticrock of Plumas County, California, are reported by H. W. Turner and A. F. Rogers, Econ. Geology, vol. 9, p. 359, 1914. 2 Zeitschr. Kryst. Min., vol. 31, 1899, p. 508. 3 Bull. Geol. Soc. America, vol. 14, 1903, p. 269. See also T. T. Read, Bull. Am. Inst. Min. Eng., March, 1906, p. 261, and E. C. Sullivan, idem, January, 1907, p. 143. * Prof. Paper U. S. Geol. Survey No. 43, 1905, pp. 182-186. 5 See Dana’s System of mineralogy, 6th ed., p. 56. 6 Econ. Geology, vol. 2, 1907, p. 14. i Bull. U. S. Geol. Survey No. 186, 1900, p. 44. 8 At Copper Mountain, British Columbia, according to Kemp (Econ. Geology, vol. 1, 1905, p. 11), the original ore was bornite; and from that mineral covellite with limonite, then chalcocite, and finally chalco- cite with chalcopyrite were successively derived. See also J. Catharinet, Eng. and Min. Jour., vol. 79, 1905, p. 125. On secondary enrichment of chalcocite ores see A. C. Spencer, Econ. Geology, vol. 8, 1913, p. 621, METALLIC ORES. 661 Among the sulphosalts there are a number containing copper, as follows: Chalcostibite CuSbS 2 . Emplectite Stylo typite 1 Cu 3 SbS 3 . Bournonite CuPbSbS 3 . Wittichenite Cu 3 BiS 3 . Aikenite CuPbBiS 3 . Enargite Cu 3 AsS 4 . Famatinite Cu 3 SbS 4 . Tennantite Tetrahedrite Cu 8 Sb 2 S 7 . Klaprotholite Cu 6 Bi 4 S 9 . Epigenite 2 Cuprobismutite The foregoing formulae are typical, and make no allowance for the frequent replacements of copper by other metals, or of bismuth, antimony, and arsenic by one another. For example, there are inter- mediate mixtures between tennantite and tetrahedrite, and bismuth, presumably as Cu 8 Bi 2 S 7 , is sometimes present in them. There are also varieties of these minerals containing very notable proportions of silver, mercury, zinc, or lead; but all reduce to the same general type of formula. 3 R. Schneider 4 by passing hydrogen sulphide into a solution con- taining bismuth trichloride and cuprous chloride, obtained a precipi- tate having the composition of wittichenite. By subsequent fusion this product assumed the character of the natural mineral. In a later investigation 5 he treated a solution of cuprous chloride with the potassium salt KBiS 2 , and produced a compound which, after special purification and fusion, resembled emplectite. He also prepared emplectite by fusing cuprous sulphide and bismuth sulphide together. The synthesis of bournonite was effected by C. Doelter 6 when a proper mixture of the chlorides or oxycompounds of copper, lead, and antimony was heated in a stream of hydrogen sulphide to a tempera- ture below redness. Above that temperature the antimony com- pounds volatilize. Evidently the sulphosalts of arsenic and anti- mony can be generated only at relatively low temperatures. By heating cuprous chloride with antimony sulphide to 300°, H. Som- merlad 7 prepared chalcostibite. Another preparation, correspond- ing to Cu 2 Sb 4 S 7 , was similarly obtained. By fusing together their 1 Copper partly replaced by silver and iron. 3 Copper partly replaced by iron. 3 On the composition of tetrahedrite (fahlerz) see A. Kretschmer, Zeitschr. Kryst. Min., vol. 48, 1910, p. 484 . 4 Pogg. Annalen, vol. 127, 1866, p. 316. 3 Jour, prakt. Chemie, 2d ser., vol. 40, 1889, p. 564. • Zeitschr. Kryst. Min., vol. 11, 1886, p. 38. 7 Zeitschr. anorg. Chemie, vol. 18, 1898, p. 420. 662 THE DATA OF GEOCHEMISTRY. component elements, in proper proportion, F. Ducatte 1 obtained emplectite, aikenite, and wittichenite. Of these sulphosalts, only enargite, tetrahedrite, tennantite, and bonrnonite are at all common. The other species are rarities. Enar- gite is an important ore at Butte, Montana, 2 and in the Tintic mines, Utah, it is the parent of a number of rare copper arsenates. Of the latter class, produced by the oxidation of enargite, W. F. Hille- brand 3 has identified olivenite, erinite, tyrolite, chalcophyllite, clino- clasite, mixite, conichalcite, and chenevixite. Several other natural arsenates of copper are known, and a number of phosphates; but they need no further consideration here. The two oxides of copper, cuprite, Cu 2 0, and tenorite, CuO, are well-known ores of secondary origin. Cuprite, which is by far the more common, has been repeatedly observed as a furnace product, 4 and also as an incrustation upon ancient objects of copper or bronze. 5 Both compounds are easily prepared synthetically. Crednerite is another oxidized compound, having the formula Cu 2 Mn 4 0 9 . An earthy oxide of manganese containing copper is known as lampadite. Cuprous chloride, nantokite, CuCl, and the iodide, marshite, Cul, are rare minerals of slight importance. The oxychloride, atacamite, Cu 2 Cl (OH) 3 , is more common, and in Chile it has some significance as an ore. 6 Several syntheses of it have been reported. F. Field 7 obtained atacamite by the action of calcium hypochlorite upon a solu- tion of copper sulphate. C. Friedel 8 obtained it by heating a solution of ferric chloride with cuprous oxide to 250°. Neither of these syn- theses, however, corresponds to any probable process in nature. The observed development of atacamite upon ancient copper and bronze gives a better notion of its genesis. G. Tschermak 9 reports an alter- ation of atacamite to malachite, and has shown that the change can be artificially reproduced when the oxychloride is slowly digested with sodium bicarbonate. Pseudomorphs of chrysocolla after ata- camite have been described by C. Barwald. 10 The sulphates of copper, normal, basic, and double, are represented by a number of mineral species, but only two of them are important. These are the normal salt, chalcanthite, CuS0 4 .5H 2 0; and the basic brochantite, Cu 4 S0 4 (0H) 6 . Chalcanthite is deposited in crystalline 1 Thesis, Univ. Paris, 1902. 2 On secondary enrichment at Butte see A. N. Rogers, Econ. Geology, vol. 8, 1913, p. 781. On the para- genesis of the Butte ores see J. C. Ray, idem, vol. 9, 1914, p. 463. For experiments relative to copper enrichment see G. S. Nishihara, idem, p. 743. s Bull. U. S. Geol. Survey No. 20, 1885, and No. 55, 1889. * See, for example, A. Arzruni, Zeitschr. Kryst. Min., vol. 18, 1891, p. 58. 6 In addition to cases already cited, see A. Lacroix, Bull. Soc. min., vol. 6, p. 175. 6 For a description of an atacamite ore body, see J. A. W. Murdoch, Trans. Inst. Min. Met., vol. 9, 1901, p. 300. 7 Philos. Mag., 4th ser., vol. 24, 1862, p. 123. 8 Compt. Rend., vol. 77, 1873, p. 211. 9 Jahrb. K.-k. geol. Reichsanstalt, vol. 23, Min. Mitt., p. 41. 10 Zeitschr. Kryst. Min., vol. 7, 1883, p. 169. METALLIC ORES. 663 form by the evaporation of cupriferous mine waters, and in some localities it is actually a workable ore. For example, at Copaquire, Chile, according to H. Oehmichen, 1 chalcanthite is found in signifi- cant quantities as an impregnation in partially decomposed granitic rocks, associated with some malachite, azurite, and chrysocolla. Pyrite and chalcopyrite are also present, the oxidation of the latter mineral having furnished the sulphate. Brochantite, a rarer species, appears to be more common than is generally supposed. W. Lind- gren 2 has called attention to its presence in the Clifton-Morenci mines of Arizona, where it occurs in fibrous forms which might easily be mistaken for malachite. F. Field 3 prepared brochantite artificially by boiling a solution of copper sulphate with a very small quantity of caustic potash. S. Meunier 4 obtained it when copper sulphate solution was allowed to act during eleven months upon fragments of galena. Apparently, brochantite is easily formed by natural reactions. Two basic carbonates of copper are common secondary ores. They are malachite, Cu 2 (0H) 2 C0 3 , and azurite, Cu 3 (0H) 2 (C0 3 ) 2 . Both species are formed in the upper portions of ore deposits, by the action of carbonated waters upon copper compounds, or by reactions between cupreous solutions and limestones. They also are found in the patina of ancient bronzes. A. de Schulten 5 prepared malachite by heating precipitated copper carbonate with a solution of am- monium carbonate on a water bath during eight days. Later, 6 upon heating a solution of copper carbonate in carbonated water, he obtained a precipitate of malachite. L. Michel 7 reproduced azurite, together with the basic nitrate, gerhardtite, by leaving a solution of copper nitrate in contact with fragments of Iceland spar for several years. Several silicates of copper are known. One of them, chrysocolla, CuSi0 3 .2H 2 0, is common; the others, dioptase, CuH 2 Si0 4 , bisbeeite, isomeric with dioptase, shattuckite, CuH 2 Si 2 0 7 , and plancheite, H 4 Cu 6 Si 5 0 18 , are rare. 8 A. C. Becquerel 9 obtained dioptase artificially by allowing a solu- tion of potassium silicate to diffuse very slowly into one of copper nitrate. Chrysocolla is probably formed by the action of percolat- ing waters, carrying silica, upon other soluble compounds of copper. Possibly, also, it may be produced during processes of secondary 1 Zeitschr. prakt. Geologic, 1902, p. 147. 2 Prof. Paper U. S. Geol. Survey No. 43, 1905, p. 119. 8 Philos. Mag., 4th ser., vol. 24, 1862, p. 123. * Compt. Rend., vol. 86, 1878, p. 686. 8 Idem, vol. 110, 1890, p. 202. 6 Idem, vol. 122, 1896, p. 1352. 7 Bull. Soc. min., vol. 13, 1890, p. 139. 8 On plancheite, see A. Lacroix, Mineralogie de la France, vol. 4, p. 757, 1910. On shattuckite and bis- beeite, see W. T. Schaller, Jour. Washington Acad., vol. 6, p. 7, 1915. » Compt. Rend., vol. 67, 1868, p. 1081. 664 THE DATA OF GEOCHEMISTRY. enrichment. E. C. Sullivan 1 has shown that powdered shale, feld- spar, biotite, etc., will withdraw copper from sulphate solutions, the reaction being one of double decomposition. The ordinary silicates lose alkalies or alkaline earths, which pass into solution and are replaced by copper. The cupriferous product may be partly silicate and partly hydrous oxides, but its investigation is as yet incomplete. MERCURY. Unlike gold, silver, and copper, mercury appears to be not widely diffused in nature, although it must be admitted that minute traces of the element are easily overlooked. Very small quantities of the precious metals can be determined by fire assay, but the volatility of mercury prevents its detection by such simple means. Apart from the natural amalgams of silver and gold, which have already been mentioned, mercury occurs in the following minerals: Native mercury. . Cinnabar Metacinnabarite 2 Tiemannite Coloradoite Onofrite Lebrbachite Livingstonite Montroy dite Calomel Terlinguaite. Eglestonite Hg. HgS. HgS. HgSe. HgTe. ■Hg(S,Se). HgSe+PbSe. HgSb 4 S 7 . HgO. Hg 2 Cl 2 . Hg 2 C10. Hg 4 Cl 2 0. To these must be added kleinite, a curious sulphato-chloride of one of the mercurammonium bases and also the allied mosesite. Ammiolite and barcenite are antimonates or antimonites of mercury, of uncertain composition. The native iodide of mercury is said to exist, but its identity is more than doubtful. Mercury is also found in some tetrahedrite, in proportions ranging as high as 17 per cent. Very few of these minerals have any economic significance. Cin- nabar is almost the sole ore of mercury, although the native metal is sometimes found in notable quantities. In some of the California mines metacinnabarite, the black sulphide, was once abundant, and tiemannite, the selenide of mercury, was commercially worked at one time in the Lucky Boy claim in Utah. 3 Livingstonite is a workable ore at Huitzuco in Mexico, and barcenite is a substance produced by its oxidation. 4 Montroydite, terlinguaite, eglestonite, mosesite, and 1 Econ. Geology, vol. 1, 1905, p. 67. Complete report in Bull. U. S. Geol. Survey No. 312, 1907. 2 Guadalcazarite is metacinnabarite containing a little zinc. 8 See G. F. Becker, Mon. U. S. Geol. Survey, vol. 13, 1888, p. 385. 4 E. Halse (Trans. North of England Inst. Min. and Mech. Eng., vol. 45, 1895 - 96 , p. 72) has described this locality. He ascribes the formation of the ores to solfataric action. J. Mactear (Trans. Inst. Min. and Met., vol. 4, 1895, p. 69), H. F. Collins (idem, p. 120), and J. D. Villarello (Mem. Soc. cient. Ant. Alzate, vol. 19, 1902, p. 94; vol. 20, 1903, p. 389; and vol. 23, 1906, p. 395) have also described the Mexican quick- silver deposits. Mactear regards them all as of aqueous and probably of thermal origin. METALLIC ORES. 665 kleinite are secondary minerals, which occur in small quantities as derivatives of cinnabar, in the mines of Brewster County, Texas. 1 Calomel has been found at several localities, but always as a secondary species. Mercuric sulphide, as shown in the list of mineral species, occurs in two forms — the red, rhombohedral cinnabar and the black, iso- metric metacinnabarite. To the one species the artificial product vermilion corresponds, while the ordinary precipitated sulphide, familiar to all analysts, is amorphous and black. Vermilion is pre- pared by many processes, which differ in detail, but can be referred to two simple types. 2 Mercury and sulphur, under the influence of heat, unite directly, and upon subliming the product the scarlet pig- ment is obtained. The other general process is based upon the fact that the black sulphide, when acted upon by solutions of alkaline sul- phides, can be converted into the red form. To these fundamental processes, the wet and the dry, the various syntheses of crystalline cinnabar correspond, with the wet methods predominating. According to Fouque and Levy, 3 J. Durocher obtained cinnabar by the action of hydrogen sulphide upon mercuric chloride at a red heat. They also state that Deville and Debray prepared the mineral by heating the black precipitated sulphide with hydrochloric acid in a sealed tube at 100°. C. Doelter’s experiments 4 were also conducted in sealed tubes. Crystals of cinnabar were formed when metallic mercury was heated with hydrogen sulphide at 70° to 90° during six days. By heating mercury with a solution of hydrogen sulphide on a water bath he also produced both cinnabar and the black modification. Several syntheses of cinnabar are based upon the solubility of mer- curic sulphide in alkaline-sulphide solutions. M. C. Mehu 5 6 found that the mercuric compound was insoluble in either sodium hydroxide or sodium sulphide, but soluble in a mixture of the two. On dilu- tion, the mixture deposited the black sulphide; but upon the passage of carbon dioxide through the solution the red modification, cinnabar, 1 See A. J. Moses, Am. Jour. Sci., 4th ser., vol. 16, 1903, p. 253. Kleinite was erroneously described by A. Sachs, Sitzungsb. K. Akad. Wiss. Berlin, 1905, p. 1091. Its true composition was first indicated by Hillebrand, Am. Jour. Sci., 4th ser., vol. 21, 1906, p. 85, and later confirmed by Sachs, Centralbl. Min., Geol. u. Pal., 1906, p. 200. For data concerning the Terlingua and other deposits of Brewster County, see B. F. Hill, Am. Jour. Sci., 4th ser., vol. 16, 1903, p. 251; E. P. Spalding, Eng. and Min. Jour., vol. 71, 1901, p. 749; R. T. Hill, idem, vol. 74, 1902, p. 305; W. B. Phillips, idem, vol. 77, 1904, p. 160; vol. 18, 1904, p. 212; M. P. Kirk and J. W. Malcolmson, idem, vol. 77, 1904, p. 684; and W. P. Blake, Trans. Am. Inst. Min. Eng., vol. 25, 1896, p. 68. For a full discussion, with analyses, of the composition of the Ter- lingua minerals, see W. F. Hillebrand and W. T. Schaller, Jour. Am. Chem. Soc., vol. 29, 1907, p. 1180, and also, in detail, in Bull. U. S. Geol. Survey No. 405, 1910. On mosesite, see Hillebrand and Schaller, Am. Join:. Sci., 4th ser., vol. 30, 1910, p. 202. 2 A good summary of the individual methods for the preparation of vermilion is given in Thorpe’s Dic- tionary of applied chemistry, vol. 3, article “Mercury.” 3 Synthase des mineraux et des roches, p. 313. These data seem not to have been published previously but to appear for the first time in the volume cited. * Zeitschr. Kryst. Min., vol. 11, 1886, p. 33. 6 Jahresb. Cheraie, 1876, p. 282. 666 THE DATA OF GEOCHEMISTRY. was formed. According to S. B. Christy, 1 amorphous mercuric sul- phide, heated in a sealed tube with alkaline solutions into which hydrogen sulphide had been passed, is converted, at temperatures between 200° and 250°, into cinnabar. This reaction is retarded by the presence of carbon dioxide. The black sulphide, by five hours of heating to 180° with a solution of potassium sulphydrate, was also transformed into cinnabar. A similar transformation of vermilion into cinnabar is also reported by A. Ditte. 2 When an excess of ver- milion is slowly acted upon by a solution of potassium sulphide it gradually changes into the crystallized mineral. The reactions, as interpreted by Ditte, are rather complex, and involve the formation and decomposition of two double sulphides, K 2 HgS 2 and K 5 Hg 5 S 6 . The results are also modified by variations in temperature and in the concentration of the solutions employed. J. A. Ippen’s 3 observa- tions resemble those of Christy. The black precipitated sulphide of mercury, heated in a sealed tube with a solution of sodium sulphide for two months below 4£°, became crystallized as cinnabar. The same black sulphide, similarly treated with hydrochloric acid, failed to yield the red form. L. L. de Koninck 4 found that mercuric sulphide is very soluble in concentrated solutions of the alkaline sulphides, and also in the sulphides of calcium, strontium, and barium, but not in solutions of sulphydrates. Upon slow dilution of the mercuric solutions thus obtained, red crystalline cinnabar was precipitated. Upon rapid dilution, the black amorphous sulphide was thrown down. E. Weinschenk 6 prepared cinnabar by a process remotely akin to those employed by Durocher and Doelter. A solution of mercuric chloride and ammonium sulphocyanate was heated in a sealed tube from four to six days at a temperature between 230° and 250°. Both cinnabar and a black sulphide were obtained. In this case the ammonium sulphocyanate merely served as a generator of hydrogen sulphide, which was the active reagent. E. T. Allen and J. L. Crenshaw 6 in a thorough study of mercuric sulphide determined the conditions of formation of the two natural forms, and also discovered a third, probably hexagonal modifica- tion, which has not been found in nature. The stable form, cinnabar, was produced in the usual way, by the action of an alkaline sulphide upon the amorphous, precipitated compound. Metacinnabarite was formed by the action of an excess of sodium thiosulphate upon sodium mercuric chloride in dilute solution. This solution was rendered slightly acid. Under alkaline conditions only cinnabar is formed; acidity is essential to the production of the less stable meta-compound. 1 Am Jour. Sci., 3d ser., vol. 17, 1879, p. 453. 2 Compt. Rend., vol. 98, 1884, pp. 1271, 1380. 3 Min. pet. Mitt., vol. 14, 1894, p. 114. * Annales Soc. gdol. Belgique, vol. 18, 1891, p. xxv. 6 Zeitschr. Kryst. Min., vol. 17, 1890, p. 498. 6 Am. Jour. Sci., 4th ser., vol. 34, 1912, p. 367 METALLIC ORES. 667 This condition also holds with regard to pyrite and marcasite, and also with the two modifications of zinc sulphide. In each case acidity controls the generation of the less stable mineral, alkalinity that of the more stable. These facts are correlated with the natural occur- rences of the minerals. Cinnabar, the primary form, is probably deposited by ascending solutions, which are commonly alkaline. Descending solutions, acid from the oxidation of iron sulphides, con- trol the formation of the secondary metacinnabarite. Finally, a crystalline mass resembling livingstonite was prepared by A. L. Baker , 1 who fused the sulphides of mercury and antimony together in an atmosphere of carbon dioxide. It will be noticed that several of the syntheses of cinnabar involve the solubility of mercuric sulphide in solutions of alkaline sulphides or sulphydrates . 2 On this subject, apart from synthetic considera- tions, there is a copious literature, and the earlier observations are by no means concordant. Even the recent data appear to be often contradictory. De Koninck, for instance, as already cited, found that the sulphide was insoluble in alkaline sulphydrates ; but according to G. F. Becker 3 this statement is true only for cold solutions. Mer- curic sulphide, heated with a solution of sodium sulphydrate on the water bath, dissolves, doubtless forming a double salt of the formula HgS.nNa 2 S. Salts of this type must be produced whenever mer- curic sulphide is dissolved in an alkaline solution, and Ditte's re- searches have told us something of their nature . 4 The solubility of the mercuric sulphide manifestly depends upon considerations of temperature, pressure, concentration, and the nature of the solutions employed, whether neutral salts, sulphydrates, or polysulphides. That mercuric sulphide is precipitated again by dilution has been shown by various observers, and Becker 5 reports admixtures of metallic mercury in the sulphide thus thrown down. Here, then, we have a possible explanation of the frequent association of free mercury and the black metacinnabarite, although relief of pressure may be in some cases the equivalent of dilution as a precipitant. Organic matter, also, is a probable agent of reduction, by which the metal is liberated. Bituminous substances, such as idrialite, nap- alite, etc., are commonly associated with cinnabar; and at the Phoenix mine in California an inflammable gas issuing from cracks in the rocks was found by W. H. Melville 6 to have the following composition: 1 Chem. News, vol. 42, 1880, p. 196. 2 According to G. A. Binder (Min. pet. Mitt., vol. 12, 1892, p. 332), even distilled water, acting on cinnabar for five weeks at 90°, will dissolve traces of the mineral. 3 Am. Jour. Sci., 3d ser.,vol. 33, 1887, p. 199. In detail, with full summaries of earlier work, in Mon. U. S. Geol. Survey, vol. 13, 1888, chapter 15. Also, preliminary, in Eighth Aim. Rept. U. S. Geol. Survey, pt. 2, 1889, p. 985. 1 A compound 2 Na 2 S. 6 HgS. 3 H 2 O has been isolated and described by J. Knox, Trans. Faraday 80 c., vol. 4, p. 29, 1908. 6 Am. Jour. Sci., 3d ser., vol. 33, 1887, p. 199. 6 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 373. 668 THE DATA OF GEOCHEMISTRY. Composition of gas at Phoenix mine. C0 2 ch 4 N 2 0 2 0.74 61. 49 31.44 6. 33 100. 00 The hydrocarbon CH 4 , it must be observed, is the first member of the paraffin series, to which some bitumens belong. Becker 1 has shown that hydrocarbons will precipitate mercuric sulphide from its alkaline solutions, first, probably, as metacinnabarite, which is after- wards slowly transformed into cinnabar. Another suggestion, due to A. Schrauf, 2 who has studied the occurrence of mercury ores in Idria, is that the metal may be liberated by the direct dissociation of cin- nabar vapor. He also ascribes the formation of some metacinnaba- rite to the action of hydrogen sulphide upon native mercury. Here again we are reminded that the same point may be reached by more than one road. According to Becker, 3 the chief deposits of mercurial ores are all in the neighborhood of igneous rocks, from which it is highly prob- able they were originally derived. The deep-seated granites, in his opinion, form the principal source of the mercury. The ore bodies in some cases fill fissures, fractures, or cavities in rocks, the latter being commonly of sedimentary character; and in other in- stances the cinnabar forms impregnations in sandstone or limestone. The ores are commonly associated with pyrite or marcasite, sulphur, calcite, barite, gypsum, opal, quartz, and other secondary minerals, and show distinct evidence that they have been brought up from below in solution. 4 In many cases, if not in all, the evidence of hydrous or solfataric origin is very clear. A. Liversidge, 5 for ex- ample, reports mercury and mercuric sulphide in hot-spring deposits near Ohaiawai, New Zealand; and in 3,403 grams of a sinter from 1 Mineral Resources U. S. for 1892, U. S. Geol. Survey, 1893, p. 139. 2 Jahrb. K.-k. geol. Reichsanstalt, vol. 41, 1892, pp. 383, 396. Schrauf gives many citations of litera- ture relative to mercury, and especially to the mines of Idria. 3 Mon. U. S. Geol. Survey, vol. 13, 1888, and also, briefly, in Mineral Resources U. S. for 1892, p. 139. In the monograph, Becker has summed up the conditions at all important localities as known in 1887. 4 In addition to Becker’s monograph, see J. A. Phillips, Quart. Jour. Geol. Soc., vol. 35, 1879, p. 390; and J. Le Conte and W. B. Rising, Am. Jour. Sci., 3d ser., vol. 24, 1882, p. 23, on Sulphur Bank, California. Le Conte (idem, vol. 25, 1883, p. 424) has discussed the deposits at Steamboat Springs, Nevada. See also, on Californian quicksilver ores, W. Forstner, Eng. and Min. Jour., vol. 78, 1904, pp. 385,426; and in Bull. Np. 27, California State Mining Bureau. Wendebom (Berg- u. hiittenm. Zeitung, vol. 63, 1904, p. 274) has described mercury deposits in Oregon; and G. F. Monckton (Trans. Inst. Min. Eng. (British), vol. 27, 1904, p. 463) those of British Columbia. For a study of the mercury mines at Mount Avala, Serbia, see H. Fischer, Zeitschr. prakt. Geologie, vol. 14, 1906, p. 245. For an account of the mines at Almaden, Spain, see H. Kuss, Annales des mines, 7th ser., vol. 13, 1878, p. 39. On Huancavelica, Peru, see A. F. Umlaufi, Bol. Cuerpo ingen. minas Peru, No. 7, 1904. F. Katzer (Berg- u. hiittenm. Jahrbuch, vol. 55, 1907, p. 145) has described the mercury deposits of Bosnia. A list of the principal mercury deposits of the world, by L. Demaret, is given in Annales des mines de Belgique, vol. 9, 1904, p. 35. 5 Jour. Roy. Soc. New South Wales, vol. 11, p. 262. See also J. Park, Trans., New Zealand Inst., vol. 38, 1904, p. 27. Park cites another memoir by A. P. Griffiths, in Trans. New Zealand Inst. Min. Eng., vol. 2, p. 48. A later report by J. M. Bell and E. de C. Clarke is in Bull. New Zealand Geol. Survey No. 8, 1909, p. 87. METALLIC ORES. 669 Steamboat Springs, Nevada, Becker and Melville 1 found 0.0070 gram of HgS. In Becker’s opinion alkaline solutions containing sulphides are the natural solvents of the mercurial compounds ; although Y. Spirek 2 describing the deposits at Monte Amiata, Tus- cany, suggests that the mercury was first dissolved as sulphate and precipitated later by alkaline polysulphides. For this supposition there seems to be little or no positive evidence. At Idria A. Schrauf 3 found no indications of the existence of alkaline thermal springs — a bit of negative testimony which may or may not be important. It is not necessary, however, to assume that the mercurial solutions have been the same at all localities. In fact, they must have varied both in their chemical composition and in the physical conditions under which they came to the surface. Even the differences in the rocks through which the solutions travel would modify their properties. ZINC AND CADMIUM. Zinc, as has been shown in the earlier portions of this chapter, is widely diffused in the rocks, and it also occurs in minute propor- tions in sea water. Cadmium is found associated with zinc, and the very rare metals gallium and indium are also obtained from zinc ores. 4 Zinc is about 200 times as abundant as cadmium. 5 Although native zinc has been several times reported, its existence is doubtful. None of the occurrences is completely authenticated. The fundamental ore of zinc is the sulphide, ZnS, known as sphal- erite, blende, or blackjack when crystallized in the isometric system, or as wurtzite when it is hexagonal. Cadmium is found almost exclusively as the sulphide, CdS, or greenockite, which is also hex- agonal. 6 Many massive blendes are really mixtures of sphalerite and wurtzite. 7 The rare mineral voltzite is an oxysulphide of zinc, 4ZnS.ZnO. Sphalerite, wurtzite, and greenockite have all been prepared syn- thetically, and wurtzite has been repeatedly observed as a furnace product. 8 According to H. de Senarmont, 9 sphalerite is formed when 1 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 344. 2 Zeitschr. prakt. Geologie, 1897, p. 369; idem, 1902, p. 297. Spirek gives references to other literature concerning Monte Amiata. See also R. Rosenlecher, Zeitschr. prakt. Geologie, 1894, p. 337, on this and other Tuscan deposits. On the mines of Vallalta-Sagron, see A. Rzehak, idem, 1905, p. 325. 3 Jahrb. K.-k. geol. Reichsanstalt, vol. 41, 1892, p. 379. * On the occurrence of gallium, indium, germanium, and other rare metals in zinc blende, see G.Urbain, Compt. Rend., vol. 149, 1909, p. 602. Also A. del Campo y Cerdan, Jour. Chem. Soc., vol. 106, pt. 2, p. 270, abstract. 6 See F. W. Clarke and G. Steiger, Jour. Washington Acad. Sci., vol. 4, 1914, p. 57. 6 A basic carbonate of cadmium and the crystallized oxide, CdO, are recently discovered minerals. A useful summary on cadmium and its occurrences, by E. Jensch, is in Ahren’s Sammlung chemische technologische Vortrage, vol. 3, 1899, p. 201. 7 See J. Noelting, Zeitschr. Kryst. Min., vol. 17, 1890, p. 220. 8 See W. Stahl, Berg-u. hiittenm. Zeitung, 1888, p. 207; H. Forstner, Zeitschr. Kryst. Min., vol. 5, 1881, p. 363; and H. Traube, Neues Jahrb., Beil. Band 9, 1894, p. 151. 8 Compt. Rend., vol. 32, 1851, p. 409. The description of the process is very vague. 670 THE DATA OF GEOCHEMISTRY. zinc solutions are heated in sealed tubes in an atmosphere of hydro- gen sulphide — a method which was also employed by H. Baubigny. 1 J. Durocher 2 prepared sphalerite by heating zinc chloride in a stream of hydrogen sulphide. Cadmium chloride treated in the same way gave greenockite. By fusing precipitated cadmium sulphide with potassium carbon- ate and sulphur E. Schuler 3 obtained crystals of greenockite. This observation has since been verified by R. Schneider. 4 H. Sainte- Claire Deville and H. Troost 5 fused zinc sulphate, calcium fluoride, and barium sulphide together, and produced crystals of wurtzite. With cadmium sulphate greenockite was formed. They also obtained wurtzite by passing hydrogen over red-hot zinc sulphide. The latter was decomposed, forming zinc vapor and hydrogen sulphide, which reacted in the cooler parts of the apparatus to produce the crystal- line mineral. Wurtzite and greenockite were prepared by T. Sidot 6 when zinc or cadmium oxide was heated in the vapor of sulphur. In another paper 7 he states that amorphous zinc sulphide, heated in an atmosphere of nitrogen or of sulphur dioxide, crystallizes into wurtzite. P. Hautefeuille 8 heated zinc and cadmium sulphide under a layer of powdery alumina; the two compounds volatilized and were redeposited on the surface of the alumina as wurtzite or greenockite. He also found that blende, heated to redness, was transformed into wurtzite. R. Lorenz 9 obtained wurtzite and greenockite by acting on the vapor of zinc or cadmium with hydro- gen sulphide. This process recalls that of Deville and Troost. Two hydrochemical processes have also yielded greenockite. C. Geitner 10 heated metallic cadmium with sulphurous acid to 200° in a sealed tube. A mixture of amorphous and crystalline sulphide was deposited. A. Ditte 11 found that amorphous cadmium sulphide could be dissolved in ammonium sulphydrate, especially at a temperature of 60°. On cooling, crystals of greenockite and free sulphur were formed. E. T. Allen and J. L. Crenshaw 12 prepared greenockite in large crystals by the method of Lorenz. Only one modification of the sulphide was obtained. Wurtzite was formed by sublimation of zinc sulphide at about 1,200°-1,300°, and also by the action of hydro- 1 See L. Bourgeois, Reproduction artificieUe des mindraux, p. 28. 2 Compt. Rend., vol. 32, 1851, p. 825. 3 Liebig’s Annalen, vol. 87, 1853, p. 34. < Poggendorf’s Annalen, vol. 149, 1873, p. 391. 6 Compt. Rend., vol. 52, 1861, p. 920. s Idem, vol. 62, 1866, p. 999. i Idem, vol. 63, 1S66, p. 188. s Idem, vol. 93, 1881, p. 824. s Ber. Deutsch. chem. Gesell., vol. 24, 1891, p. 1501. Liebig’s Annalen, vol. 129, 1864, p. 350. ” Compt. Rend., vol. 85, p. 402, 1877. I 2 Am. Jour. Sci., 4th ser., vol. 34, 1912, p. 341; vol. 38, 1914, p. 873. METALLIC ORES. 671 gen sulphide, derived from sodium thiosulphate, on acid solutions of zinc sulphate at 250°. By heating amorphous zinc sulphide in a solution of sodium sulphide at 350° in a steel bomb they obtained good crystals of sphalerite. Sphalerite was also produced, like wurtzite, in acid solutions, but with weaker acid and at higher temperatures. In alkaline solutions only sphalerite was formed. This distinction between the two minerals is like that already mentioned with regard to the sulphides of mercury and of iron. Sphalerite was also crys- tallized from solution in molten sodium chloride and potassium polysulphide. At 1,020° sphalerite is transformed into wurtzite. For geological purposes the hydrochemical syntheses of blende are the only ones of much importance; and they are paralleled by certain natural and recent occurrences of the mineral. G. Bischof, 1 for example, mentions a sinter, formed within historical times in an old lead mine, which contained 37.57 per cent of ZnS. It was prob- ably produced by the action of decaying wood upon the zinc-bearing mine waters. In North St. Louis, Missouri, H. A. Wheeler 2 found massive blende embedded in lignite, where it had evidently been formed by the reducing action of organic matter upon other zinc compounds. C. R. Keyes 3 speaks of blende crystals, one-fourth inch across, which had grown on iron nails immersed in a mine water during fifteen years. W. P. Jenney 4 also refers to the deposition of crystallized blende on the walls of a tunnel which had been closed and flooded for ten or twelve years. Some crystals were deposited on the pick marks left by the miners. Zinc sulphide is also known in nature as a chemical precipitate. In workings at Galena, Kansas, large cavities have been found, filled with a white mud which consisted of nearly pure zinc sulphide mingled with acid water. 5 Evidently the zinc had been dissolved, probably by the oxidation of blende, and then thrown down again, either by sulphureted waters or by organic matter. Natural solu- tions of zinc sulphate exist in the region around Joplin, and have already been described in previous portions of this volume. 6 An occurrence of sphalerite as a primary mineral in granite has been reported by E. Rimann. 7 Such sphalerite, if really of magmatic origin, must have formed below the transition temperature to wurt- zite, namely, 1,020°. 1 Lehrbuch der chemischen und physikalischen Geologie, 2d ed., vol. 1, p. 559. 2 Trans. Acad. Sci. St. Louis, vol. 7, 1895, p. 123. Other associations of sphalerite wLh coal, also in Missouri, are mentioned by W. P. Jenney, in Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 460. 8 Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 611. * Idem, vol. 33, 1903, p. 470. 6 Described by J. D. Robertson, Am. Jour. Sci., 3d ser., vol. 40, 1890, p. 160; and by M. W. lies and J. D. Hawkins, Eng. and Min. Jour., vol. 49, 1890, p. 499. ® See ante, p. 188. 7 Zeitschr. prakt. Geologie, 1910, p. 123. 672 THE DATA OF GEOCHEMISTRY. The oxidized compounds of zinc, as natural minerals, are fairly numerous. The following species are especially noteworthy: Zincite Gahnite 1 Franklinite 1 . . . Chalcophanite 1 Smithsonite Hydrozincite. . . Willemite 2 Calamine Clinohedrite — Hardystonite. . . Hodgkinsonite. ZnO. . ZnAl 2 0 4 . .ZnFe 2 0 4 . . Zn0.2Mn0 2 .2H 2 0. ZnC0 3 . ZnC0 3 .2Zn0 2 H 2 . .Zn 2 Si0 4 . Zn 2 H 2 Si0 5 . ZnCaH 2 SiO s . ZnCa 2 Si 2 0 7 . Zn 2 Mn(Si0 4 )(0H) 2 . To this list may be added the phosphates, hopeite 3 and kehoeite; the arsenates, adamite, kottigite, and veszelyite; descloizite, a vana- date of lead and zinc; and the sulphates, goslarite and zincaluminite. Jeffersonite is a zinc-bearing pyroxene, and danalite is a silicate plus sulphide, of zinc, manganese, iron, and glucinum. None of these species needs further mention except goslarite, ZnS0 4 .7H 2 0, which is the compound of zinc existing in mine waters and in zinciferous springs. When zinc is removed from an ore body by solution, it is carried in this form. Zincite, the natural oxide of zinc, is well known as a furnace prod- uct, and it has also been repeatedly synthetized. 4 According to A. Daubree, 5 when zinc chloride and water vapor act upon lime at a red heat, zincite is formed. Ferrieres and Dupont 6 obtained it, at a similar temperature, by the action of steam upon zinc chloride alone. By heating the amorphous oxide in an atmosphere of oxygen, T. Sidot 7 was able to effect its crystallization. A. Gorgeu 8 prepared the mineral by several processes, one of which consisted in the gradual calcination of zinc sulphate or nitrate. In this case better results were obtained when an alkaline sulphate was mingled with the zinc salt. Zincite was also formed when a mixture of zinc fluoride and potassium fluoride was strongly heated in a current of steam. The zinc spinels, gahnite and franklinite, have also been arti- ficially prepared. J. J. Ebelmen 9 obtained gahnite by fusing a mixture of alumina, zinc oxide, and boron trioxide. When ferric oxide 1 The formulae here given are ideal. Part of the zinc is commonly replaced by manganese or iron. 2 Troostite is a manganiferous willemite. 3 For a synthesis of hopeite, see C. Friedel and E. Sarasin, Bull. Soc. min., vol. 2, 1879, p. 153. 4 See H. Traube, Neues Jahrb., Beil. Band 9, 1894, p. 151; and H. Ries, Am. Jour. Sci., 3d ser., vol. 48, 1894, p. 256, on zincite as a furnace product. See also J. T. Cundell and A. Hutchinson, Mineralog. Mag., vol. 9, 1892, p. 5. L. Bourgeois (Reproduction artificielle des min&aux) cites other examples, and so, too, does Ries. Bourgeois also mentions syntheses by Becquerel and Regnault, but his references are erroneous and I can not verify them. 5 Compt. Rend., vol. 39, 1854, p. 135. 6 See Bourgeois, op. cit., p. 56. 7 Compt. Rend., vol. 69, 1869, p. 201. 8 Idem, vol. 104, 1887, p. 120. 9 Annales chim. phys., 3d ser., vol. 33, 1851, p. 34. METALLIC ORES. 673 was used in place of alumina, franklinite was formed. By vapor- izing aluminum chloride and zinc chloride over lime at a red heat, A. Daubree 1 prepared gahnite; and franklinite was similarly produced by -using the chlorides of iron and zinc. H. Sainte-Claire Deville and H. Caron 2 obtained gahnite by vaporizing a mixture of zinc and aluminum fluorides in presence of boric oxide. A. Stelzner 3 found gahnite, with fayalite, in the walls of a muffle of a zinc furnace at Freiberg, where it had been formed by the action of zinc vapors upon the clay silicates. In another similar case, H. Schulze and Stelzner 4 report the formation of willemite and tridymite. The occurrence of crystallized willemite in a furnace slag has also been recorded by W. M. Hutchings. 5 According to A. Daubree, 1 willemite can be prepared by the action of silicon tetrachloride upon zinc oxide at a red heat. This, how- ever, was denied by H. Sainte-Claire Deville, 6 who found that wiflem- ite was decomposed by silicon chloride. It is formed when silicon fluoride acts upon zinc oxide, and also by the action of zinc fluoride upon heated silica. A. Gorgeu 7 produced willemite by two proc- esses. First, zinc sulphate, calcined with an alkaline sulphate and silica, yields willemite and tridymite. Secondly, the mineral is formed when zinc chloride is fused with silica in presence of steam. By heating metallic zinc with seltzer water in a sealed tube at 100°, L. Bourgeois 8 obtained crystals of smithsonite. G. Bischof 9 cites a number of instances in which zinc carbonate has formed as a deposit from natural waters. In nature, zinc ores occur under a variety of conditions — in true metalliferous veins, in metamorphic rocks, and under circumstances which indicate a sedimentary origin. In some cases they form meta- somatic replacements of limestone. Percolating solutions of zinc, permeating limestones, would necessarily react upon the latter, the zinc being deposited as carbonate in place of the removed lime com- pounds. Pseudomorphs of smithsonite after calcite are well known. In an experiment reported by G. Piolti, 10 a fragment of calcite, immersed during 17 J years in a solution of zinc sulphate, became coated with smithsonite and gypsum. In the introduction to this chapter evidence was adduced showing that zinc was present, albeit in small amounts, in Archean rocks, from which it may be concentrated. It is also found in diffused 1 Compt. Rend., vol. 39, 1854, p. 135. 2 Idem, vol. 46, 1858, p. 766. 3 Neues Jahrb., Band 1, 1882, p. 170. * Idem, Band 1, 1881, p. 120. 5 Geol. Mag., 3d ser., vol. 7, 1890, p. 31. 6 Compt. Rend., vol. 52, 1861, p. 1304. 7 Idem, vol. 104, 1887, p. 120. * 8 Reproduction artificielle des min4raux, p. 144. 9 Lehrbuch der chemischen und physikalischen Geologic, 2d ed., vol. 1, p. 561. 10 Jour. Chem. Soc., vol. 100, p. 902, 1911. Abstract. 97270°— Bull. 616—16 43 674 THE DATA OF GEOCHEMISTRY. traces in many sedimentary rocks. L. Dieulafait 1 detected zinc in hundreds of samples of Jurassic limestone from central France. J. D. Robertson 2 found it, with lead and copper, in the limestones of Mis- souri, and J. B. Weems 3 determined lead and zinc in the limestones and dolomites of the Dubuque region, Iowa. The average of nine samples analyzed by Weems gave 0.00326 per cent Pb and 0.00029 per cent Zn. Robertson’s figures are as follows for six Silurian mag- nesian limestones and seven limestones from the “ Lower” Carbon- iferous; they are stated in percentages. Lead , zinc , and copper in limestones. Silurian. Lower Carboniferous. T.po.rl Trace to 0.00156 Trace to 0.00346 Trace to 0.00255 Zinc 0.00016 to 0.01536 C!nr>r»pr 0.00040 to 0.00256 Trace to 0.00880 Small as these proportions are, they are sufficient to account for the formation of the ore bodies in the regions studied. In each region a comparatively moderate amount of decomposition of the country rocks would supply the ores contained in the known deposits. 4 Similar results to those of Weems and Robertson were obtained by A. M. Finlayson 5 6 in his study of the British lead and zinc deposits. These metals were found in the country rocks in quantities of the same order of magnitude, and were more abundant in the granites than in the limestones. Finlayson regards the metals as having been brought up in solution from below, in waters which contained alka- line sulphides and also fluorine. The order of deposition of the vein minerals was chalcopyrite, first, then fluorite, blende, galena, and finally pyrite. This association of sphalerite with other sulphides is very general, so much so that economic geologists usually consider lead and zinc together. In the famous ore bodies of the Mississippi Valley the two ores are rarely found quite apart, although in one locality zinc may predominate, while lead is the chief thing of value in another. Cal- cite, dolomite, and sometimes fluorite or barite are frequent com- panions of the ores, and bituminous matter is often present also. By alteration of sphalerite, surface deposits of calamine and smithsonite are formed, just as oxidized ores are developed above bodies of copper sulphide. Secondary crystallizations of sphalerite are also common where solutions of zinc sulphate, formed near the top of an ore body, 1 Compt. Rend., vol. 90, 1880, p. 1573, and vol. 96, 1883, p. 70. 2 Missouri Geol. Survey, vol. 7, 1894, pp. 479-481. 3 Cited by S. Calvin and H. F. Bain, Iowa Geol. Survey, vol. 10, 1900, p. 566. -4 See T. C. Chamberlin, Geology of Wisconsin, vol. 4, 1882, pp. 367-553, and A. Winslow, Missouri Geol. Survey, vols. 6 and 7, especially vol. 7, 1894, p. 467, etc. 6 Quart. Jour. Geol. Soc., vol. 66, 1910, p. 299. METALLIC ORES, 675 have percolated downward, and been reduced to sulphide again. It is highly probable that pyrite or marcasite may react upon the zinc- bearing solutions and aid in the regeneration of the sphalerite. Some experiments by H. N. Stokes/ carried out in the laboratory of the United States Geological Survey, have shown the possibility of such reactions. Pyrite and marcasite heated to 180° with solutions of zinc salts and alkaline carbonates actually yield zinc sulphide. Sphalerite sometimes occurs in stalactitic forms, which could be deposited only from solutions. The calamine and smithsonite are sometimes pure and crystalline, sometimes quite impure and earthy. The so-called “ tallow clays” of Missouri and Arkansas are zinc-bearing clays, prob- ably mixtures of aluminous silicates with calamine, and they contain from 4 or 5 per cent up to 56 per cent of zinc oxide. 1 2 Similar clays, from an ore body at Leadville, Colorado, were analyzed by W. F. Hillebrand. 3 On the sedimentary lead and zinc ores of the Mississippi Valley there is a copious literature, with much discussion about genetic prob- lems. Some authorities derive the ores from ascending, heated waters; some find their proximate sources in the adjacent limestones, and others trace them still further back to Archean rocks, or argue that the zinc and lead were deposited with the sediments from solu- tion in the Silurian ocean. All agree, however, that the ores were deposited from solution, which is the essential fact for the geochemist to consider. 4 1 Econ. Geology, vol. 2, 1907, p. 17. See also the work of Anthon, Schiirmann, and others, already cited on p. 639, ante. 2 See W. H. Seamon, Am. Jour. Sci., 3d ser., vol. 39, 1890, p. 38; and J. C. Branner, Ann. Rept. Arkan- sas Geol. Survey, vol. 5, 1892, pp. 9-34. Both authors give analyses, and other analyses by T. M. Chatard and H. N. Stokes can be found in Bull. U. S. Geol. Survey No. 228, 1904, pp. 361, 362. A similar clay from Bertha, Virginia, with 12.1 per cent ZnO, was described by B. H. Heyward, Chem. News, vol. 44, 1881, p. 207. s Mon. U. S. Geol. Survey, vol. 12, 1886, p. 603. * For data concerning these deposits, see J. D. Whitney, Rept. Geol. Survey Wisconsin, vol. 1, chapter 6, 1862; T. C. Chamberlin, Geology of Wisconsin, vol. 4, 1882, pp. 367-553; W. P. Blake, Bull. Geol. Soc. America, vol. 5, 1893, p. 25; U. S. Grant, Bull. Wisconsin Geol. Nat. Hist. Survey No. 9, 1903, and Bull. U. S. Geol. Survey No. 260, 1905, p. 305; E. E. Ellis, idem, p. 310; A. G. Leonard, Iowa Geol. Survey, vol. 6, 1897, pp. 13-65; and Am. Geologist, vol. 16, 1905, p. 288; H. F. Bain, Bull. U. S. Geol. Survey No. 225, 1904, p. 202; A. Winslow, Missouri Geol. Survey, vols. 6 and 7, 1894, and Jour. Geology, vol. 1, 1893, p. 612; J. D. Robertson, Am. Geologist, vol. 15, 1895, p. 235; Bain, Van Hise, and Adams, Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 2, 1902, p. 23; W. P. Jenney, Trans. Am. Inst. Min. Eng., vol. 22, 1894, pp. 171, 642; E. Hedburg, idem, vol. 31, 1901, p. 379; J. C. Branner, Ann. Rept. Arkansas Geol. Survey, vol. 5, 1892, and Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 572; G. I. Adams, idem, vol. 34, 1904, p. 163; Bull. U. S. Geol. Survey No. 213, 1903, p. 187, and Prof. Paper U. S. Geol. Survey No. 24, 1904; W. S. T. Smith, Bull. U. S. Geol. Survey No. 213, 1903, p. 196, and A. Keith, Bull. U. S. Geol. Survey No. 225, 1904, p. 208. See also W. H. Case, Trans. Am. Inst. Min. Eng., vol. 22, 1894, p. 511, on the zinc ores of Bertha, Virginia, S. F. Emmons (Trans. Am. Inst. Min. Eng., vol. 22, 1894, p. 83) briefly discusses the origin of zinc ores, and so too does C. R. Van Hise in his Treatise on metamorphism, Mon. U. S. Geol. Survey, vol. 47, 1904, pp. 1125-1158. A zinc deposit in Nevada is described by Bain, Bull. U. S. Geol. Survey No. 285, 1906, p. 166. Other publications are by E. Haworth and others, Kansas Univ. Geol. Survey, vol. 8, 1904; E. R. Buck- ley and H. A. Buehler, Missouri Bur. Geology and Mines, 2d ser., vol. 4, 1906; H. F. Bain, Bull. U. S. Geol. Survey No. 294, 1907; T. L. Watson, Bull. Am. Inst. Min. Eng., March, 1906. See also Bain, Bull. Wisconsin Geol. Nat. Hist. Survey No. 19, 1907; L. C. Snider, Oklahoma Geol. Survey, Bull. No. 9, 1912; G. H. Cox, Econ. Geology, vol. 6, 1911, p. 427. On the genesis of the Ozark deposits, see C. R. Keyes, Bull. Am. Inst. Min. Eng., 1909, p. 119, 676 THE DATA OF GEOCHEMISTRY. The zinc mines at Franklin and Sterling Hill, New Jersey, are of a different type from those of the Mississippi Valley, being indeed unique. Here zincite, franklinite, and willemite, ores which are rare minerals elsewhere, are most abundant, while blende is present only in insignificant quantities. The ore bodies occur in crystalline lime- stone, in contact with gneiss, and the limestone is pierced by numer- ous granitic dikes. It seems probable, from the character of the ores and their mineralogical associations, that they were formed by con- tact metamorphism. A bed of limestone containing calamine and smithsonite, together with other impurities, might be expected to change, by thermal metamorphosis, into just such a formation as that at Franklin. The smithsonite would yield zincite, the willemite might be formed from calamine, and the franklinite and gahnite, with other spinels, could develop exactly as members of the spinel group develop in ordinary limestones. This hypothesis needs verification, but it is plausible and simple. In southwestern New Mexico, accord- ing to W. P. Blake , 1 zinc ores occur in a contact-metamorphosed limestone; but blende is the principal mineral. Blake, however, is inclined to correlate this deposit with that at Franklin, notwith- standing their differences . 2 LEAD. Although lead is one of the commoner heavy metals, native lead is exceedingly rare. It is known, however, from several localities, but it is always of secondary origin, a product of reduction . 3 The principal ore of lead is the normal sulphide, galena, PbS. Allied to this are the rare selenide, clausthalite, and altaite, the cor- responding telluride . 4 The synthetic preparation of galena has been effected by various methods, both wet and dry. J. Durocher 5 obtained it by the action of hydrogen sulphide upon lead chloride at a red heat. Any other salt of lead would probably serve the same purpose. Even the silicate of lead contained in glass, according to T. Sidot , 6 when heated in the vapor of sulphur, yields galena. F. Stolba 7 produced crystals of the sulphide by heating the amorphous compound to dull redness with chalk. F. de Marigny 8 produced 1 Trans. Am. Inst. Min. Eng., vol. 24, 1895, p. 187. 2 For data regarding the Franklin region, see F. L. Nason, Ann. Rept. State Geologist New Jersey, 1890, p. 25; and J. F. Kemp, Trans. New York Acad. Sci., vol. 13, 1893, p. 76. Kemp gives references to earlier literature. See also J. E. Wolff, Bull. U. S. Geol. Survey No. 213, 1903, p. 214, and A. C. Spencer, Ann. Rept. State Geologist New Jersey, 1908, and Geol. Atlas U. S., U. S. Geol. Survey, Franklin Furnace folio (No. 161), 1908. 3 A. Hamberg (Zeitschr. Kryst. Min., vol. 17, 1890, p. 253) has suggested that at Harstig, Sweden, the lead was reduced by arsenious oxide. * Nagyagite is a sulphotelluride of lead, gold, and antimony. Naumannite, lehrbachite, and zorgite are selenides of lead with silver, mercury, or copper. 6 Compt. Rend., vol. 32, 1851, p. 825. See also A. Carnot, cited by L. Bourgeois, Reproduction artificielle des min^raux, p. 30. 6 Compt. Rend., vol. 62, 1866, p. 999. 7 Jahresb. Chemie, 1863, p. 242. 8 Compt. Rend., vol. 58, 1864, p. 967. METALLIC ORES. 677 galena by fusing litharge with iron pyrites and starch. F. Roessler 1 crystallized both galena and clausthalite from solution in molten lead. By distillation of a mixture containing lead oxide, sulphur, and ammonium chloride, E. Weinschenk 2 also prepared crystals of galena. It is furthermore to be noted that galena is not uncommon in furnace slags, and that Mayen^on 3 has reported its formation as I a product of sublimation in a burning coal mine. The foregoing syntheses of galena have small geological signifi- cance. In nature, the mineral appears to be commonly formed by hydrochemical reactions, and these can be imitated in the laboratory. C. Doelter 4 allowed lead chloride, sodium bicarbonate, and a solution of hydrogen sulphide in water to remain in a sealed tube at ordinary room temperature during five months. Crystals of galena were thus formed. E. Weinschenk 5 heated a solution of lead nitrate with ammonium sulphydrate to 180° in a sealed tube and also obtained galena. H. N. Stokes 6 has found that pyrite or marcasite, heated with a solution of lead chloride to 180°, will precipitate lead sul- phide. A. Daubree 7 observed the formation of galena, together with anglesite and phosgenite, by the action of the thermal waters of Bourbonne-les-Bains on metallic lead. Lead sulphide is also known in spring deposits, 8 and as a pseudomorphous replacement of other minerals. W. Lindgren 9 mentions replacements of calcite, dolomite, and quartz, and also of orthoclase and rhodonite. W. H. Hobbs 10 has described secondary galena as a surface film on cerusite, formed probably by the action of hydrogen sulphide on the latter mineral. That galena itself is slightly soluble in water and also in solutions of sodium sulphide has been shown by C. Doelter. 11 A. Gautier 12 has shown that galena is dissociated into its elements by the action of steam at a red heat. A little galena volatilizes and is redeposited in crystalline form, and some also is converted into sulphate. The pres- ence of galena among the Vesuvian sublimates, mentioned in an earlier chapter of this volume, may be correlated with Gautier’s observations. 1 Zeitschr. anorg. Chemie, vol. 9, 1895, p. 41. By passing selenium vapor over melted lead G. Little (Liebig’s Annalen, vol. 112, 1859, p. 211) also produced the selenide. 2 Zeitschr. Kryst. Min., vol. 17, 1890, p. 489. * Compt. Rend., vol. 86, 1878, p. 491. * Zeitschr. Kryst. Min., vol. 11, 1886, p. 41. A. C. Becquerel (Compt. Rend., vol. 44,1857, p.938) men- tions a hydrochemical synthesis of galena, but too vaguely to warrant citation above. s Zeitschr. Kryst. Min., vol. 17, 1890, p. 497. 6 Econ. Geology, vol. 2, 1907, p. 22. 7 Etudes synthStiques de geologie expdrimentale, pp. 84, 85. s See, for example, the sinter described by G. F. Becker and W. H. Melville, Mon. U. S. Geol. Survey, vol. 13, 1888, p. 344. 9 Trans. Am. Inst. Min. Eng., vol. 30, 1900, p. 578. 10 Am. Jour. Sci., 3d ser., vol. 50, 1895, p. 121. w Min. pet. Mitt., vol. 11, 1890, p. 31,9. An iron wedge or chisel coated with galena is mentioned in Min- eralog. Mag., vol. 16, 1913, p. 340. u Compt. Rend., vol. 142, 1906, p. 1465. 678 THE DATA OF GEOCHEMISTRY. The sulphosalts of lead are numerous, although, on account of their individual rarity, they have little significance as ores. 1 Sarto- rite, dufrenoysite, guitermanite, jordanite, rathite, and lengenbachite are sulpharsenides. Zinkenite, plagionite, jamesonite, semseyite, boulangerite, meneghinite, geocronite, kilbrickenite, and epiboulan- gerite are sulphantimonides. Other sulphantimonides of lead and silver are brongniardite, diaphorite, freieslebenite, and andorite. The sulphobismuthides are chiviatite, rezbanyite, galenobismutite, schirmerite, cosalite, schapbachite, kobellite, lillianite, and beegerite. Teallite, cylindrite, and franckeite are sulphostannides, which, for present purposes, must be classified under tin. According to J. Fournet, 2 zinkenite, PbSb 2 S 4 , can be prepared by fusing galena and stibnite together in proper proportions. C. Doel- ter, 3 by heating antimony, antimony trioxide, and lead chloride together in gaseous hydrogen sulphide, obtained jamesonite, PbSb 2 S 5 , mixed with stibnite and galena. By the action of molten lead chlo- ride upon antimony trisulphide, H. Sommerlad 4 reproduced boulan- gerite, Pb 3 Sb 2 S 6 ; zinkenite; jamesonite; warrenite 5 (domingite), Pb 3 Sb 4 S 9 ; and plagionite, Pb 5 Sb 8 S 17 . By fusing lead sulphide and arsenic trisulphide together, he obtained sartorite (scleroclase), PbAs 2 S 4 , and dufrenoysite, Pb 2 As 2 S 5 . G. Pelabon, 6 studying the fusion curve of the system PbS + Sb 2 S 3 , found that . zinkenite crystallized out at 558°, and jamesonite at 610°. F. M. Jaeger and H. S. van Klooster, 7 by a similar process, obtained only jamesonite and plagionite. The component sulphides were fused together in an atmosphere of nitrogen. They assert that Sommerlad’ s syntheses are incorrect. Whether any of these syntheses correspond to natural processes is questionable. The ore bodies in which the minerals occur appear to have been formed in most cases from mineralized solutions, or else by pneumatolytic reactions at temperatures which were not exces- sively high. Syntheses, to be geologically significant, should be con- ducted on the lines which nature seems to have followed. 8 By oxidation, carbonation, etc., the sulphur compounds of lead are transformed into other minerals. Among them are the three oxides, 1 Bournonite and aikinite, which contain both lead and copper, have already been mentioned under the latter metal. 2 Cited by L. Bourgeois, Reproduction artificielle des minSraux, p. 46, from Jour, prakt. Chemie, vol. 2, p. 490. 3 Zeitschr. Kryst. Min., vol. 11, 1886, p. 40. * Zeitschr. anorg. Chemie, vol. 18, 1898, p. 420. Sommerlad ’s results have been called in question by F. Ducatte (Thesis, Univ. Paris, 1902) and J. Rondet (Thesis, Univ. Paris, 1904), who claim that the reac- tions employed really produce complex chlorinated sulphides, and not true sulphosalts. 6 According to L. J. Spencer (Mineralog. Mag., vol. 14, 1907, p. 207), warrenite is identical with jame* sonite. W. T. Schaller (Zeitschr. Kryst. Min., vol. 48, 1911, p. 562) regards it as a mixture of jamesonite and zinkenite. ® Compt. Rend., vol. 156, p. 706, 1913. 7 Zeitschr. anorg. Chemie, vol. 78, p. 245, 1912. 8 Jamesonite forms an important ore at La Sirena, near Zimapan, Mexico. See W. Lindgren and W. L. Whitehead, Econ. Geology, vol. 9, 1914, p. 435. METALLIC ORES. 679 massicot, PbO; minium, Pb 3 0 4 ; and plattnerite, Pb0 2 . All these have been prepared synthetically in crystalline form, but in most cases by methods which scarcely resemble natural processes. A. C. Becquerel, 1 by allowing an alkaline solution of alumina or silica to act slowly upon a plate of lead, obtained crystals of massicot. The lead was surrounded by a coil of copper wire, and Becquerel attributed the synthesis to electrical action. It was more probably a simple hydro- chemical process. Lead carbonate, cerusite, PbC0 3 , is a common mineral, produced by the action of carbonated waters in the upper levels of ore bodies. 2 There are also the basic hydrocerusite, Pb 3 (OH) 2 (C0 3 ) 2 , and the rare dundasite, a carbonate of aluminum and lead. 3 Becquerel 4 obtained crystals of cerusite when a solution of sodium and calcium carbonate acted gradually upon a plate of lead. E. Fremy 5 produced the mineral by the slow diffusion of a carbonate solution into a lead solution through a porous membrane. By some such gradual min- gling of dilute solutions, the natural cerusite is probably often formed. 6 H. von Dechen 7 has reported the case of an old mine whose walls were covered with a thick coating of cerusite, which had been deposited from solution like sinter. A. Lacroix 8 has observed the mineral as a coating on old Roman coins. It is also produced by metasomatic replacement in limestones, and fossils, such as encrinites, have been found completely transformed into cerusite. 9 The rare chloro- carbonate of lead, phosgenite, Pb 2 Cl 2 C0 3 , was reproduced by C. Friedel and E. Sarasin 10 when lead chloride, lead carbonate, and water were heated together in a sealed tube to 180°. It was also prepared by A. de Schulten, 11 who allowed a filtered solution of lead chloride to stand in a large flask while a current of carbon dioxide passed slowly through the vacant space above. Cotunnite, lead chloride, PbCl 2 , is found in nature as a volcanic mineral, produced by sublimation. F. Stober 12 reproduced the min- eral by this process, and also obtained it in minute crystals from simple solution in water or in aqueous hydrochloric acid. It was also 1 Compt. Rend., vol. 34, 1852, p. 29. See also, for other researches, L. Bourgeois, Reproduction artificielle des min6raux, p. 56. L. Michel (Bull. Soc. min., vol. 13, 1890, p. 56) reports syntheses of minium and plattnerite. 2 A large deposit of cerusite in the Terrible mine, at Ilse, Colorado, has been described by R. B. Brins- made, Eng. and Min. Jour., vol. 83, 1907, p. 844. Its formation is ascribed to the action of descending waters. 3 See G. T. Prior, Mineralog. Mag., vol. 14, 1906, p. 167. * Loc. cit. 5 Compt. Rend., vol. 63, 1866, p. 714. « The syntheses of cerusite, by J. Riban (Compt. Rend., vol. 93, 1881, p. 1026), and of hydrocerusite, by L. Bourgeois (Bull. Soc. min., vol. 11, 1888, p. 221), have no relation to natural processes. i Neues Jahrb., 1858, p. 216. s Bull. Soc. min., vol. 6, 1883, p. 175. 9 See Blode, Neues Jahrb., 1834, p. 638. w Bull. Soc. min., vol. 4, 1881, p. 175. 11 Idem, vol. 20, 1897, p. 194. 12 Bull. Acad. roy. sci. Belgique, 3d ser., vol. 30, 1895, p. 345. 680 THE DATA OF GEOCHEMISTRY. formed by A. C. Becquerel, 1 much earlier, by allowing a solution of copper sulphate and sodium chloride to act upon galena during a period of seven years. The sulphate, anglesite, was obtained at the same time. The great rarity of cotunnite as a natural mineral is due to the strong tendency on the part of lead to form basic salts, and the basic chlorides are much more frequently found. Matlockite, Pb 2 OCl 2 , and mendipite, Pb 3 0 2 Cl 2 , have long been known. Schwartzembergite is like mendipite in composition, but with iodine largely replacing chlorine. Laurionite, 2 paralaurionite, penfieldite, daviesite, and fied- lerite are oxychlorides of lead which have formed on ancient slags at Laurium, in Greece. Caracolite is a double salt of the composition Pb0HCl + Na 2 S0 4 . Percylite, cumengeite, and pseudoboleite are oxychlorides of lead and copper, and boleite is similar in composition, but with silver chloride as an additional component. 3 Lead sulphate, PbS0 4 , as the crystallized mineral anglesite, is a common oxidation derivative of galena. According to E. Jannetaz 4 galena is easily attacked by acid solutions of ferrous sulphate such as are generated by the oxidation of pyrite or marcasite. The associa- tion of galena with pyrite, therefore, is favorable to the formation of anglesite. Its synthesis by Becquerel has already been mentioned, and it has also been prepared by Mace, 5 who added a solution of fer- rous sulphate very slowly to one of lead nitrate. Essentially the same process was successfully followed by E. Fremy 6 and by E. Masing, 7 a soluble sulphate being allowed to diffuse very slowly into one of a lead salt — in Masing’s case lead nitrate. Lead sulphate, although relatively insoluble, is not absolutely so; it therefore can be crystallized, as the syntheses show, when it is formed with extreme slowness in very dilute solutions. Conditions of this sort probably attend the formation of anglesite in bodies of lead ore; but when car- bonates are present in the percolating waters, cerusite is produced instead. The synthesis of anglesite by N. S. Manross, 8 who obtained it by fusing lead chloride with potassium sulphate, does not seem to correspond with any natural mode of formation. Lanarkite is a rare, basic sulphate of lead, Pb 2 S0 5 . 9 Caledonite and linarite are basic sulphates of lead and copper, and plumbojaro- 1 Compt. Rend., vol. 34, 1852, p. 29. 2 For a synthesis of laurionite, PbOHCl, see A. de Schulten, Bull. Soc. min., vol. 20, 1897, p. 186. On the rare minerals of Laurium, see A. Lacroix and De Schulten, Bull. Soc. min., vol. 31, 1908, p. 79. Georgiaddsite, a phosphate and chloride of lead, should be added to the list. 3 Percylite, cumengeite, and boleite have been made artificially by C. Friedel, Bull. Soc. min., vol. 15, 1892, p. 96; vol. 16, 1893, p. 187; and vol. 17, 1894, p. 6. See also, in reference to these minerals, E. Mallard, Bull. Soc. min., vol. 16, 1893, p. 184, and G. Friedel, idem, vol. 29, 1906, p. 14. * Bull. Soc. g6ol. France, 3d ser., vol. 3, 1875, p. 310. G. Piolti (Jour. Chem. Soc., vol. 100, 1911, p. 902, abstract) obtained crystals of anglesite by the prolonged immersion of galena in a solution of potassium nitrate. b Compt. Rend., vol. 36, 1853, p. 825. « Idem, vol. 63, 1866, p. 714. 7 Jahresb. Chemie, 1889, p. 4. 8 Liebig’s Annalen, vol. 82, 1852, p. 348. 9 For a synthesis of lanarkite, see A. de Schulten, Bull. Soc. min., vol. 21, 1898, p. 142. METALLIC ORES. 681 site and beaverite basic sulphates of lead and ferric iron. Leadhillite is a complex salt of the formula PbS0 4 .2PbC0 3 .Pb(0H) 2 . At Granby, Missouri, according to W. M. Foote, 1 it occurs as a pseudomorph after calcite and galena. In composition it suggests a double salt formed by the union of hydrocerusite and anglesite, in equimolecular proportions. 2 Plumbojarosite, a highly hydrated sulphate of lead and iron, is abundant in some mines in Utah. 3 Lead salts analogous to anglesite are the chromate, crocoite, PbCr0 4 ; the molybdate, wulfenite, PbMo0 4 ; and the tungstate, stol- zite, PbW0 4 . The rare phoenicochroite 4 is a basic chromate, Pb 3 Cr 2 0 9 ; vauquelinite is a chromate and phosphate, and beresovite is described as a chromate and carbonate of lead, which is not, how- ever, the equivalent of leadhillite, for it contains no water. When sodium tungstate is fused with lead chloride, according to N. S. Manross, 5 stolzite is formed; with sodium molybdate, wulfen- ite is produced; and by fusing together potassium chromate and lead chloride he obtained crocoite. The formation of wulfenite as a furnace product 6 is probably due to some reaction of this kind. By slow diffusion of solutions of potassium chromate and lead nitrate into one another A. Drevermann 7 obtained both crocoite and phceni- cochroite. Cerusite and anglesite were formed at the same time from impurities in the reagents. A. C. Becquerel 8 allowed a gal- vanic couple of lead and platinum to act for several years upon a solution of chromic chloride and obtained crystals which appeared to be crocoite. S. Meunier 9 found that phoenicochroite was formed when fragments of galena were immersed during six months in a solution of potassium dichromate. L. Bourgeois 10 boiled precipitated lead chromate with dilute nitric acid. From the hot, filtered solu- tion crystals of crocoite were deposited. Better results were obtained when the operation was conducted in a sealed tube at 130°. Lachaud and Lepierre 11 state that when amorphous lead chromate is boiled with a solution of chromic acid it crystallizes into crocoite. Phoeni- cochroite was formed when lead chromate and sodium chloride were fused together. Both chromates were obtained by Ludeking 12 upon 1 Am. Jour. Sci., 3d ser., vol. 50, 1895, p. 99. 2 Palmierite, a double sulphate of lead and potassium, is found among the recent products of fumarole action at Vesuvius. a In certain of the mines of Beaver County, plumbojarosite is abundant enough to be treated as an ore of lead. See B. S. Butler, Econ. Geology, vol. 8, 1913, p. 311. * Also called melanochroite. 6 Liebig’s Armalen, vol. 82, 1852, p. 348. H. Schultze (idem, vol. 126, 1863, p. 51) prepared wulfenite in the same way. e See J. F. L. Hausmann, idem, vol. 81, 1852, p. 224. 7 Idem, vol. 87, 1853, p. 120; vol. 89, 1854, p. 11. 8 Compt. Rend., vol. 63, 1866, p. 1. 8 Idem, vol. 87 , 1878, p. 656. 10 Bull. Soc. min., vol. 10, 1887, p. 187. 11 Bull. Soc. chim., 3d ser., vol. 6, 1891, p. 230. 12 Am. Jour. Sci., 3d ser., vol. 44, p. 57. 682 THE DATA OF GEOCHEMISTRY. exposing to the air during several months a solution of lead chromate in caustic potash. G. Cesaro 1 prepared crocoite by the same process, and with lead molybdate crystalline wulfenite was formed. E. Dittler 2 added a hot, concentrated solution of lead chloride to a dilute solution of ammonium molybdate, and obtained an amor- phous precipitate. This, dissolved in a solution of sodium carbonate, was gradually redeposited as wulfenite. Natural wulfenite, digested with sodium bicarbonate, yielded hydrocerusite. Of all these syn- theses, that by Meunier seems best to represent the probable natural processes. Three lead minerals, the chlorophosphate, pyromorphite, Pb 5 P 3 0 12 Cl; the corresponding arsenate, mimetite, Pb 5 As 3 0 12 Cl; and the vanadium salt, vanadinite, Pb 3 V 3 0 12 Cl, occur both independently and in a great variety of isomorphous mixtures. Endlichite, for example, is a mixture of the arsenic and vanadium compounds, and minerals intermediate between mimetite and pyromorphite are common. All these species have been prepared synthetically, and pyromor- phite is also known as a furnace product in slag. 3 N. S. Manross 4 obtained pyromorphite by fusing lead chloride with tribasic sodium phosphate. H. Sainte-Claire Deville and H. Caron 5 fused lead phos- phate, lead chloride, and sodium chloride together to produce pyro- morphite, and L. Michel 6 accomplished the same purpose by the same process, only omitting the common salt. From fusions of lead arsenate with lead chloride G. Lechartier 7 and also Michel succeeded in reproducing mimetite. Vanadinite was obtained by P. Haute- feuille 8 when vanadic ’ oxide was fused with lead oxide and lead chloride. All of these syntheses, it will be seen, are similar and were effected by fusion, while the natural occurrences of the minerals indi- cate hydrochemical reactions. In the case of pyromorphite this natural process was simulated by H. Debray, 9 who prepared pyro- morphite by digesting lead pyrophosphate with a solution of lead chloride at 250°. Other phosphates, arsenates, and vanadates containing lead and sometimes zinc, iron, or copper also, are plumbogummite, caryinite, carminite, lossenite, bayldonite, ecdemite, beudantite, 10 svanhergite, hinsdalite, descloizite, cuprodescloizite, brackebuschite, and psittaci- 1 Bull. Acad. roy. sci. Belgique, 1905, p. 327. 2 Zeitschr. Kryst. Min., vol. 53, 1914, p. 158. s J. J. Noggerath, Neues Jahrb., 1847, p. 37. < Liebig’s Annalen, vol. 82, 1852, p. 348. 6 Annales chim. phys., 3d ser., vol. 67, 1863, p. 451. 6 Bull. Soc. min., vol. 10, 1887, p. 133. i Compt. Rend., vol. 65, 1867, p. 172. 8 Idem, vol. 77, 1873, p. 896. • Annales chim. phys., 3d ser., vol. 61, 1861, p. 443. Phosphate, arsenate, and sulphate of lead. Svanbergite, hinsdalite, and the sulphate, beaverite. are allied to beudantite. metallic; ores. 683 nite. Bindheimite is a lead antimonate, formed by oxidation from sulphosalts of lead. Nadorite, PbClSb0 2 , and ochrolite, Pb 6 Cl 2 Sb 2 0 7 , are perhaps of similar origin. All of these species are rare minerals and need not be considered further. The same may be said of the lead-bearing silicates, barysilite, ganomalite, hyalotekite, kentrolite, melanotekite, nasonite, roeblingite, and molybdophyllite. The roeblingite, however, from the zinc mines at Franklin, New Jersey, is unique in containing a sulphite molecule combined with the silicate. An artificial lead silicate from furnace slag has been described by E. S. Dana and S. L. Penfield, 1 and also by H. A. Wheeler. 2 The common association of lead ores with those of zinc was pointed out in the preceding section of this chapter. Blende and galena are both formed from solutions, but not always in the same manner. By differences in the solubility of their oxidation products the two metals are often separated from each other, for lead sulphate is slightly soluble, while zinc sulphate is easily so. Zinc, therefore, disappears from the upper portions of ore bodies much more rapidly than lead, and, for the same reason, so does copper. The lead ores of Eureka, Nevada, are regarded by J. S. Curtis 3 as the product of solfataric action; those of Leadville, Colorado, according to S. F. Emmons, 4 were deposited from descending solutions, which had gath- ered their metallic burden from neighboring eruptive rocks. In both cases the ore bodies are interpreted as replacements in country rock. TIN . 5 Tin is one of the rarer metals and its ores are not numerous. Native tin is occasionally found, but never in more than trifling quan- tities and in small grains. 6 The ore of chief importance is the dioxide, cassiterite, Sn0 2 , but several sulphosalts are also known. They are — Stannite Cu 2 FeSnS 4 . Teallite 7 PbSnS 2 . Cylindrite Pb 3 FeSn 4 Sb 2 S 14 . Franckeite Pb 5 FeSn 3 Sb 2 S 14 . 1 Am. Jour. Soi., 3d ser., vol. 30, 1885, p. 138. 2 Idem, vol. 32, 1886, p. 272. 3 Mon. U. S. Geol. Survey, vol. 7, 1884, chapters 7, 8. 4 Idem, vol. 12, 1886, p. 378. & For a paper on the occurrence and distribution of tin, with a bibliography, see F. L. Hess and L. C. Graton, Bull. U. S. Geol. Survey No. 260, 1904, p. 160. A summary of tin localities is also given by W. P. Blake, in Mineral Resources U. S. for 1883-84, U. S. Geol. Survey, 1885, pp. 592 et seq. 6 A recent discovery of native tin is noted by E. S. Simpson in Ann. Rept. Geol. Survey West Australia, 1899, p. 52. 7 See G. T. Prior, Mineralog. Mag., vol. 14, 1904, p. 21, on the composition of teallite, cylindrite, and franckeite. See also A. Stelzner, Neues Jahrb., Band 2, 1893, p. 114, and A. Frenzel, idem, p. 125. On stannite and its alteration products from the Black Hills, see W. P. Headden, Am. Jour. Sci., 3d ser., vol. 45, 1893, p. 105. 684 THE DATA OF GEOCHEMISTRY. There is also a very rare borate of calcium and tin, nordenskiol- dine, 1 CaSnB 2 0 6 , which is interesting because it directly connects tin with boron. The same is true of hulsite and paigeite, two iron-tin borates found in Alaska. 2 Other minerals, especially those of the rare earths, sometimes contain small amounts of tin as an impurity, and the metal has also been found in zinc blende. 3 Cassiterite has been repeatedly observed as a furnace product, formed by the direct oxidation of tin. Recent occurrences of this kind are recorded by A. Arzruni 4 and J. H. L. Vogt, 5 and L. Bour- geois 6 has identified the mineral in scoria from a bronze foundry. The first synthesis of cassiterite was performed by A. Daubree 7 when the vapor of stannic chloride was mixed with steam in a red-hot porcelain tube. Later the same chemist 8 prepared the mineral by passing the vapor of stannic chloride over heated lime. The crystal- lized oxide was obtained by H. Sainte-Claire Deville and H. Caron 9 when stannic fluoride and boric oxide were heated together to white- ness. H. Sainte-Claire Deville 10 also obtained it by heating the amorphous oxide in a slow current of hydrochloric acid gas and again by a repetition of Daubree’s first process. A. Ditte 11 noticed the formation of crystalline stannic oxide when the amorphous com- pound, mixed with calcium chloride and ammonium chloride, was subjected to a white heat. According to C. Doelter, 12 cassiterite is perceptibly soluble in water at 80°, and more so in presence of sodium fluoride. Some recrystal- lization from the solution was observed. This solubility is also indicated by several natural occurrences of tin. S. Meunier 13 found 0.5 per cent of Sn0 2 in an opaline deposit, resembling geyserite, from a thermal spring in Selangor. J. H. Collins 14 reports tinstone as a cement in certain Cornish conglomerates, as an impregnation in long- buried horns of deer, as pseudomorphs after feldspar, 15 and as cap- 1 Described by W. C. Brogger, Zeitschr. Kryst. Min., vol. 16, 1890, p. 61. 2 See A. Knopf and W. T. Schaller, Am. Jour. Sci., 4th ser., vol. 25, 1908, p. 323. Also Schaller, idem, vol. 29, 1910, p. 543. 3 See A. Stelzner and A. Schertel, Jahrb. Berg- u. Hiittenw. Konig. Sachsen, 1886, p. 52, on tin in black blende from Freiberg. It has also been found in the zinc ores of the Slocan district, British Columbia. See Kept. Comm, on Zinc Resources, etc., of British Columbia, Mines Branch, Dept. Interior, Ottawa, 1906, p. 15. * Zeitschr. Kryst. Min., vol. 25, 1896, p. 467. & Idem, vol. 31, 1899, p. 279. 6 Bull. Soc. min., vol. 11, 1888, p. 58. 7 Compt. Rend., vol. 29, 1849, p. 227. 3 Idem, vol. 39, 1854, p. 135. 9 Idem, vol. 46, 1858, p. 764. Details not given. w Idem, vol. 53, 1861, p. 161. a Idem, vol. 96, 1883, p. 701. 12 Min. pet. Mitt., vol. 11, 1890, p. 325. is Compt. Rend., vol. 110, 1890, p. 1083. h Mineralog. Mag., vol. 4, 1880, pp. 1, 103, and vol. 5, 1883, p. 121. 10 According to C. Reid and J. B. Scrivenor (Mem. Geol. Survey Eng. and Wales, Geology of country near Newquay, 1906, p. 39), the so-called pseudomorphs are replacements of orthoclase by an aggregate of cassiterite, muscovite, and quartz. On the genesis of the Cornish ores, see also J. B. Hill and D. A. Mae- Alister, idem, Geology of Falmouth, Truro, etc., p. 167. METALLIC ORES. 685 pings on crystals of quartz. He also notes that cassiterite crystals often line fissures in quartz, the latter containing numerous fluid inclusions. An incrustation resembling “wood tin” was found by Collins on an ingot of ancient tin, having been formed by slow oxi- dation of the metal. Furthermore, Collins reports secondary crystal- lizations of cassiterite on reniform masses of “wood tin,” and all of this evidence he regards as proof that the Cornish ores are of aqueous origin. Pseudomorphs of cassiterite after hematite were found by F. A. Genth 1 in tin ores from Durango, Mexico, and he also cites an observation by W. Semmons, who described specimens of bis- muthinite coated with concentric layers of tinstone. It is possible in some of these cases that the tin-bearing solutions may have been derived from the oxidation of stannite, but this point seems to have received little or no consideration. Stalactitic cassiterite, from the Sierra de Guanajuato, Mexico, has been described by E. Wittich . 2 Cassiterite has been noted as an original constituent of igneous rocks , 3 but it more commonly occurs in veins or stringers of quartz under conditions which indicate a secondary deposition. As a rule, tin-bearing veins are found in or near persilicic rocks, such as pegma- tites and altered granites. Sometimes the association is with quartz porphyry, as at Mount Bischoff, in Tasmania , 4 and at certain Mexican mines; but at other localities of tin in Mexico the prevailing rock is rhyolite or rhyolite tuff. In these instances, as at the Potrillos mine, in Durango, the ore is found along fault planes in the rhyolite . 5 The Cacaria mine, also in Durango, is in quartz porphyry. In the Malay Peninsula, according to R. A. F. Penrose , 6 the prevalent stanniferous rocks are granitic, or detrital matter derived from granite; but at Chongkat Pari, in Perak, cassiterite is extracted from limestone, and at Bruseh, Perak, it is found in seams in sand- stone. These abnormal occurrences are perhaps due, as Penrose suggests, to infiltration of tin-bearing solutions — a supposition which becomes probable in the light of evidence already cited. The typical mode of occurrence of tin ores is in quartz veins cut- ting granite, the walls of the latter rock being altered into greisen. Greisen is essentially a granite in which the feldspars have been 1 Proc. Am. Philos. Soc., vol. 24, 1887, p. 23. L. V. Pirsson (Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 407) has described crystals of hematite inclosing cassiterite, from the same locality. 2 Zeitschr. prakt. Geologie, 1910, p. 121. 2 See ante, p. 353, in chapter on rock-for ming minerals. 4 On Tasmanian tin deposits see L. K. Ward, Bull. Geol. Survey Tasmania, No. 6, 1909. Earlier separate papers by G. A. Waller and W. H. Twelvetrees were issued by the same office. On the Mount Bischoff mines, see W. von Fircks, Zeitschr. Deutsch. geol. Gesell., vol. 51, 1899, p. 431. 5 See C. W. Kempton, Trans. Am. Inst. Min. Eng., vol. 25, 1896, p. 997, and W. R. Ingalls, idem, p. 147. On the Sain Alto mines, Zacatecas, see E. Halse, idem, vol. 29, 1900, p. 502, and J. N. Nevius, Eng. and Min. Jour., vol. 75, 1903, p. 920. This locality is also rhyolitic. On the tin deposits of Guanajuato, see A. H. Bromly, Trans. Am. Inst. Min. Eng., vol. 36, 1906, p. 227. 6 Jour. Geology, vol. 11, 1903, p. 135. On the ores of Banca and Billiton, see R. Beck, Zeitschr. prakt. Geologie, 1898, p. 121. W. R. Rumbold (Bull. Am. Inst. Min. Eng., September, 1906) has described the tin deposits of the Kinta Valley, Malay States. He mentions deposits in limestone. 686 THE DATA OF GEOCHEMISTRY. transformed into mica and of which topaz and tourmaline are fre- quent constituents. The mica is often, but not invariably, lithia hearing, either ordinary lepidolite or zinnwaldite. Bismuth ores, wolfram, and arsenopyrite are common associates of the tinstone. These mineralogical data, the usual presence in stanniferous veins of species containing fluorine and boron, and also the alteration of the granite walls, have led to the very general belief that tin deposits of the ordinary type have been formed by the injection of vapors carry- ing the two elements above named and also the tin. This belief is strengthened by the various syntheses of cassiterite, in which boric oxide and chloride or fluoride of tin have taken part. The signifi- cance of the very rare mineral nordenskioldine, with its tin and boron together, here becomes apparent, although the species has not been found in any vein or deposit of the usual stanniferous type, but only in a dike of elseolite syenite. Ordinarily the two elements are sepa- rated, the boron going to the tourmaline molecules and the tin to form cassiterite. Fluorine is represented by topaz, fluorite, or apa- tite, and sometimes by the lithia-bearing phosphates triphylite and amblygonite . 1 In some localities formerly worked for tin the lithia minerals, especially amblygonite and lepidolite, are now the species of chief commercial value. American deposits of tin, more or less resembling those of Cornwall and Saxony, are found in the York region, Alaska; in Rockbridge County, Virginia, and near El Paso, Texas. The Alaskan field has been well studied by A. J. Collier 2 and A. Knopf , 3 who describe both lodes and placers. The typical cassiterite is disseminated in more or less altered granitic dikes, essentially greisen, consisting of quartz, zinnwaldite, calcite, and fluorspar. In one case the ore is intimately associated with tourmaline, and other borates and borosilicates, including the rare minerals hulsite and paigeite, are also found. It also occurs in veins which cut through metamorphic slates — a rather unusual development. At the Cash mine, in Virginia, accord- ing to L. C. Graton , 4 the ore is in quartz veins in granite, the walls of the veins being converted into greisen. W. H. Weed 5 and G. B. Richardson 6 have studied the tin deposits of the Franklin Mountains 1 For discussions on the genesis of cassiterite veins, see A. Daubree, Etudes synthetiques de geologic experimentale, pp. 28-71; J. H. L. Vogt, Zeitschr. prakt. Geologie, 1895, p. 145, and Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 125; and W. Lindgren, idem, vol. 30, 1900, p. 578. See also F. Gautier, Actes Soc. sci. Chili, vol. 5, 1895, p. 92. R. Recknagel (Trans. Geol. Soc. South Africa, vol. 12, 1910, p. 128) attributes the South African tin deposits to magmatic differentiation, and in part to concentration by lateral secretion. 2 Bull. U. S. Geol. Survey No. 229, 1904; and also in Bull. No. 225, 1903, p. 154; Bull. No. 259, 1905, p. 120; and Eng. and Min. Jour., vol. 76, 1903, p. 999. s Bull. U. S. Geol. Survey No. 345, 1908, p. 251; No. 358, 1908, and Econ. Geology, vol. 4, 1909, p. 214. See also A. H. Brooks, Mineral Resources U. S. for 1900, U. S. Geol. Survey, 1901, p. 267, and Bull. No. 213, 1902, p. 92; and E. Rickard, Eng. and Min. Jour., vol. 75, 1903, p. 30. * Bull. U. S. Geol. Survey No. 293, 19Q6, p. 44. See also T. Ulke, Mineral Resources U. S. for 1893, U. S. Geol. Survey, 1894, p. 178. 6 Bull. U. S. Geol. Survey No. 178, 1901, and also in Bull. No. 213. 1902, p. 170. 6 Bull. U. S. Geol. Survey No. 285, 1905, p. 146, METALLIC ORES. 687 near El Paso, where the ore is found in quartz under conditions which Weed thinks resemble those of Cornwall. The Temescal deposit, in southern California, as described by H. W. Fairbanks, 1 may also be- long to the class. The vein material consists almost wholly of tour- maline and quartz, formed by gradual replacement of the granite walls. Another mode in which cassiterite occurs is as an original con- stituent in pegmatite. It is thus found, although scantily, in the famous localities in Maine for lithia tourmalines and lepidolite. The workable cassiterite of the Carolina tin belt, according to L. C. Graton, 2 is also in pegmatite, none being found in the wall rock. Here again lithia minerals are found, namely, lithiophilite and spodumene. The tin ores of the Black Hills, in South Dakota, seem to belong under this heading, and the Etta mine especially is noted for its enormous crystals of spodumene and columbite. In this locality crystalline faces of spodumene are exposed which are from 30 to 40 feet long; and in the Ingersoll claim a single mass of colum- bite is said to have weighed more than 2,000 pounds. 3 Cassiterite in pegmatite, accompanied by corundum, is reported by P. F. Molengraaf 4 from Swazieland, South Africa. The tin ores of Bolivia represent still another class of associations. Cassiterite in masses resembling hematite, and the four sulphosalts of tin, are here found in veins carrying ores of silver, lead, and bismuth in rocks of recent volcanic origin. According to A. W. Stelzner 5 the rock is commonly dacite or trachyte; but at Potosi, as described by A. F. Wendt, 6 the matrix is rhyolite. The vein matter is quartz, with carbonates and barite. In these deposits we evidently have a transition between the ordinary tin-bearing vein and the type of vein characterized by silver-lead ores. W. R. Rum- bold, 7 who has studied the Bolivian deposits, regards them as of pneumatolytic origin. ARSENIC, ANTIMONY, AND BISMUTH. Arsenic, antimony, and bismuth are three closely related elements. Arsenic, from a purely chemical point of view, is a nonmetal; for, despite its metallic appearance, it is an acid-forming element, and only in exceptional cases does it play the part of a base. Antimony 1 Am. Jour. Sci., 4th ser., vol. 4, 1897, p. 39. 2 Bull. U. S. Geol. Survey No. 293, 1906, and also in Bull. No. 260, 1904, p. 188. Other papers on the Carolina belt are by J. H. Pratt, Mineral Resources U. S. for 1903, U. S. Geol. Survey, 1904, p. 337, and Pratt and I). B. Sterrett, Bull. North Carolina Geol. Survey No. 19, 1904. 2 See W. P. Blake, Trans. Am. Inst. Min. Eng., vol. 13, 1885, p. 691. On the Black Hills mines, see also E. W. Claypole, Am. Geologist, vol. 9, 1892, p. 228, and J. D. Irving, Prof. Paper U. S. Geol. Survey No. 26, 1904, p. 95. 4 See abstract in Zeitschr. prakt. Geologie, 1900, p. 146. 5 Zeitschr. Deutsch. geol. Gesell., vol. 49, 1897, p. 51. See also M. Frochot, Annales des mines, 9th ser., vol. 19, 1901, p. 186. 6 Trans. Am. Inst. Min. Eng., vol. 19, 1890, p. 90. 7 Econ. Geology, vol. 4, 1909, p. 321. 688 THE DATA OF GEOCHEMISTRY. is more commonly acid than basic, but in bismuth the basic character is strongly predominant, except in its sulphosalts. All three elements &re found native, and also in many closely related compounds. Among the latter the sulphosalts of silver, lead, copper, and tin have already been mentioned, and few others remain to be named. Berthierite is a sulphantimonite of iron, FeSb 2 S 4 , and lorandite is a sulpharsenite of thallium, T1 AsS 2 . There are also a number of arsenides, antimonides, and bismuthides of silver, copper, nickel, cobalt, platinum, etc., which are best con- sidered under the several metals that characterize them. For present purposes it is enough to mention the iron arsenides, loHingite, FeAs 2 , and leucopyrite, Fe 3 As 4 , and also the sulpharsenide, arseno- pyrite, FeAsS. Arsenopyrite or mispickel is the most important ore of arsenic. Native arsenic, native antimony, and native bismuth are all rather common minerals, and with them the arsenide of antimony, allemon- tite, SbAs 3 , may be grouped. There are also natural sulphides, selenides, and tellurides, as follows : Realgar AsS. Orpiment As 2 S 3 . Stibnite Sb 2 S 3 . Metastibnite Sb 2 S 3 . Bismuthinite Bi 2 S 3 . Guanajuatite Bi 2 Se 3 . Tetradymite Bi 2 Te 3 . Joseite 1 Bi 2 Te. Wehrlite 1 Bi 3 Te 2 . Griinlingite Bi 4 TeS 3 . Kermesite Sb 2 S 2 0 . Several of these minerals have been produced artificially. J. Durocher 2 prepared stibnite and bismuthinite by the action of hydrogen sulphide upon the volatilized chlorides of antimony and bismuth. H. de Senarmont 3 found that when pulverized realgar or orpiment was heated to 150° with a solution of sodium bicarbonate in a sealed tube they dissolved and were later redeposited as crystal- lized realgar. Amorphous antimony sulphide, treated in the same way at 250°, also dissolved and crystallized as stibnite. The pre- cipitated sulphide of bismuth, similarly heated to 200° with a solu- tion of an alkaline sulphide, gave crystals of bismuthinite. E. Wein- schenk 4 obtained orpiment and stibnite by heating solutions of arsenic or antimony with ammonium sulphocyanate to 180° in a sealed tube. According to A. Carnot, 5 stibnite and bismuthinite are easily 1 Formula approximate only. Sulphur or selenium partly replaces tellurium. 2 Compt. Rend., vol. 32, 1851, p. 825. 2 Annales chim. phys., 3d ser., vol. 32, 1851, p. 129. 4 Zeitschr. Kryst. Min., vol. 17, 1890, p. 497. 5 See L. Bourgeois, Reproduction artificielle des mineraux, pp. 41,42. METALLIC ORES. 689 formed by passing hydrogen sulphide at a dull red heat over other compounds of antimony or bismuth. Kealgar, orpiment, stibnite, and bismuthinite are all reported by Mayen^on 1 as found among the sublimation products of a burning coal mine. 2 C. Doelter 3 states that stibnite at 80° is slightly soluble in water and that recrystallization from the solution is also perceptible. The same statement holds for arsenopyrite, FeAsS. In several localities the deposition of arsenical or antimonial sulphides from hot springs has been observed. W. H. Weed and L. V. Pirsson 4 report both realgar and orpiment from a hot spring in the Yellowstone National Park, and G. F. Becker 5 found sulphides of arsenic and antimony in a sinter at Steamboat Springs, Nevada. In 3,403 grams of this sinter, as analyzed by W. H. Melville, were found the following sub- stances : Sulphides, etc., found in sinter. Grams. Au 0.0034 A g 0012 HgS 0070 PbS 0720 CuS 0424 Sb 2 S 3 +As 2 S 3 78.0308 Fe 2 0 3 3.5924 The antimony sulphide was in the amorphous, orange-colored form, to which Becker gave the name of metastibnite. Crystals of ordinary stibnite have since been discovered by W. Lindgren 6 in the same sinter, apparently of quite recent formation. The locality, it must be observed, is one which yields mercury, and G. F. Becker 7 has reported stibnite from several quicksilver mines in California. A similar association of stibnite and cinnabar is found at Monte Amiata in Tuscany; 8 and at Huitzuco, Mexico, stibnite occurs with living- stonite, kermesite, baroenite, and some cinnabar in a matrix of gyp- sum. 9 Cinnabar has also been noted in the antimony mines of Cor- sica. 10 According to Coquand, 11 the antimonyores at Pereta, Tuscany, are of solfataric origin. This mode of deposition, which genetically connects antimony and mercury, may be ascribed to the fact that 1 Compt. Rend., vol. 86, 1878, p. 491; vol. 92, 1881, p. 854. 2 On the conditions governing the formation of orpiment and realgar, see W. Borodowsky, Sitzungsb. Naturf. Gesell. Univ. Dorpat, vol. 14, p. 159. Also in Chem. Abstracts, vol. 1, 1907, p. 1106. 3 Min. pet. Mitt., vol. 11, 1890, p. 322. * Am. Jour. Sci., 3d ser., vol. 42, 1891, p. 401. At another spring in the Park, Arnold Hague (idem, vol. 34, 1887, p. 171) found a deposit of scorodite, an arsenate of iron. 5 Mon. U. S. Geol. Survey, vol. 13, 1888, p. 344. e Trans. Am. Inst. Min. Eng., vol. 36, 1906, p. 27. 7 Op. cit., p. 389 0 s B. Lotti, Zeitschr. prakt. Geologie, 1901, p. 43. 9 J. G. Aguilera, Trans. Am. Inst. Min. Eng., vol. 32, 1902, p. 307. 10 Nentien, Annales des mines, 9th ser., vol. 12, 1897, p. 251. 11 Bull. Soc. geol. France, 2d ser., vol. 6, 1848-49, p. 91. 97270°— Bull. 616—16 44 690 THE DATA OF GEOCHEMISTRY. both metals form easily volatile compounds. The same property is shared by arsenic, but deposits of other than solfataric nature are known. At least there are deposits in which no indication of sol- fataric action can now be discerned. The sulphides of arsenic and antimony are easily soluble in alkaline solutions, and in that way may be transported to points far distant from their original ore bodies. The sulphide of bismuth is much less soluble. Stibnite is the most important ore of antimony. Its deposition from solution is in most cases evident, and its alkaline solutions, which also dissolve silica, seem to have formed the typical occur- rences, in which stibnite is intimately associated with quartz. It is so found in the mines of Sevier County, Arkansas ; 1 in Mexico, and in Corsica, where the ore bodies occur in sericitic schists. At Kostainik, in Serbia, according to R. Beck and W. von Fircks , 2 the stibnite is found in trachyte, in graywacke, and also as replacements in lime- stone. Arsenopyrite also occurs most commonly with quartz, oftenest in metamorphic schists and sometimes in serpentine . 3 When either arsenic, antimony, or bismuth is found in a metalliferous vein, asso- ciated with silver, copper, or lead, it is usually combined with those metals in the form of sulphosalts. By oxidation of the sulphides, a large number of secondary min- erals can be formed. First of all are the oxides, as follows: Arsenolite 4 5 Claud etite 4 Senarmontite Valentjnite Cervantite Bismite, or bismuth ocher Stibiconite As 2 0 3 , isometric. As 2 0 3 , monoclimc. Sb 2 0 3 , isometric. Sb 2 0 3 , orthorhombic. . Sb 2 0 4 . Bi 2 0 3 .3H 2 0. H 2 Sb 2 0 5 . Bismuth also forms two basic carbonates, bismutite and bismuto- sphserite, and a rare oxychloride, daubreeite. The oxides of antimony form important ore bodies at Altar, Sonora, Mexico , 6 and in Neoco- mian limestone at Mount Hamimat, Province of Constantine, Algeria . 7 From oxidation of the sulphosalts, a large number of arsenates, antimonates, and various compounds of bismuth have been derived. 1 SeeC. E. Wait, Trans. Am. Inst. Min. Eng., vol. 8, 1879, p. 42; J. C. Branner, Ann. Rept. Arkansas Geol. Survey, 1888, vol. 1, p. 136; and G. H. Ashley, Proc. Am. Philos. Soc., vol. 36, 1897, p. 306. 2 Zeitschr. prakt. Geologie, 1900, p. 33. 3 On the arsenic mines of Hastings County, Ontario, see J. W. Wells, Rept. Bur. Mines Ontario, 1902, p. 101. J. L. Cowan (Eng. and Min. Jour., vol. 78, 1904, p. 105) has described an arsenic mine at Brinton, Virginia. For the antimony mines of Nova Scotia, see W. R. Askwith, Canadian Min. Rev., vol. 20, 1901, p. 173. 4 The true molecular weight, as shown by the vapor density, is more probably represented by the formula AS 4 O 6 . A similar doubling may be proper for the other oxides and sulphides of this group. 5 On the composition of bismuth ocher, see W. T. Schaller, Jour. Am. Chem. Soc., vol. 33, 1911, p. 162. 6 E. T. Cox, Am. Jour. Sci., 3d ser., vol. 20, 1880, p. 421. 7 Coquand, Bull. Soc. g6ol. France, 2d ser., vol. 9, 1851-52, p. 342. METALLIC ORES. 691 Some of these were mentioned in the preceding sections of this chap- ter; others are salts of calcium, magnesium, iron, or manganese. For example, pharmacolite is an arsenate of lime, pharmacosiderite an arsenate of iron, and sarkinite an arsenate of manganese. Atopite, schneebergite, and romeite are antimonates of lime. Some of these compounds, and there are many others, may have been formed by the action of percolating arsenical or antimonial solutions upon carbo- nates of lime, magnesia, manganese, or iron, or upon hydroxides of the two metals last named. There are also arsenates of bismuth, and a tellurate, a vanadate, a molybdate, and a silicate of the same base. The strange mineral longbanite is an antimonio-silicate of manganese and iron; derbylite and lewisite are antimonio-titanates of iron and lime, respectively; and mauzeliite is a similar salt of calcium and lead. Derbylite, lewisite, and tripuhyite, Fe 2 Sb 2 0 7 , are found in the cinna- bar-bearing gravels of Tripuhy, Brazil. 1 They were derived from mica schists, but their association with cinnabar is suggestive. NICKEL AND COBALT . 2 Among the minor constituents of igneous rocks, nickel is one of the commonest. Cobalt also is widely diffused, but in much smaller proportions. 3 In 262 analyses of igneous rocks made in the labora- tory of the United States Geological Survey an average of 0.0274 per cent of nickel oxide was found. Had it been sought for in all cases, this figure might have been slightly reduced, but perhaps not materially. Nickel and cobalt are characteristic elements in meteoric irons, and also in terrestrial irons of similar character. Indeed, some of the “irons” of which analyses are given in another chapter of this book 4 are more truly described as native nickel, that being the metal which predominates in them. Awaruite and josephinite are nickel irons of this kind, in which the percentage of nickel reaches * 60 or even more, 1 See E. Hussak and G. T. Prior, Mineralog. Mag., vol. 11, 1895, pp. 80, 176, 302. 2 For a general paper upon nickel and its occurrences, see P. Argali, Proc. Colorado Sci. Soc., vol. 4, 1893, p. 395. A note by A. G. Charlton follows (p. 420) on Colorado nickel ores. On nickel in the Mansfeld copper shales, see Baeumler, Zeitschr. Deutsch. geol. Gesell. , vol. 9, 1857, p. 25. On cobalt ores at Schweina, Thuringia, see F. Beyschlag, Zeitschr. prakt. Geologie, 1898, p. 1. On cobalt in Mexico, G. de J. Caballero, Mem. Soc. cient. Ant. Alzate, vol. 18, 1902, p. 197. O. Stutzer (Zeitschr. prakt. Geologie, 1906, p. 291) has described tourmaline-bearing cobalt veins at San Juan, Atacama, Chile. The ore is cobaltite. 3 On the wide diffusion of cobalt and nickel in nature, see K. Kraut, Zeitschr. angew. Chemie, 1906, p. 1793, 4 See ante, p. 331. 692 THE DATA OF GEOCHEMISTRY. The ores of these metals fall into three principal classes, namely, sulphides or arsenides, oxides, and silicates. In the first case the chief minerals are as follows: Millerite NiS. Beyrichite Ni 3 S 4 . Polydymite 1 Ni 4 S 5 . Niccolite NiAs. Chloanthite NiAs 2 . Kammelsbergite NiAs 2 . Gersdorffite NiAsS. Pentlandite 3 (Fe,Ni)S. Jaipurite CoS. Linnaeite Co 3 S 4 . Smaltite CoAs 2 . Safflorite Skutterudite 2 Cobaltite CoAsS. Carrollite .Co 2 CuS 4 . Two other arsenides of nickel have recently been described ; 4 maucherite and temiskamite. A careful study of the two by Chase Palmer, however, has shown that they are identical, and that the true formula is Ni 4 As 3 . With these minerals we may include the nickel telluride, melonite, and the antimonide, breithauptite, NiSb. Ullmannite is a sulphide of antimony and nickel, 5 NiSbS. Corynite and wolfachite are mix- tures of a salt of the last type with the corresponding salt NiAsS. Glaucodot is sulpharsenide of cobalt and iron, and alloclasite is sim- ilar, but with bismuth partly replacing arsenic. Another mineral of the formula NiCoS 2 Sb 2 has been named willyamite. Arsenides and antimonides of nickel are known as accidental fur- nace products. 6 The crystalline sulphides of cobalt and nickel have also been repeatedly prepared artificially. H. de Senarmont 7 heated solutions of potassium sulphide with nickel or cobalt chloride to tem- peratures between 160° and 180° in a sealed tube, and obtained the compounds NiS, Ni 3 S 4 , and Co 3 S 4 , corresponding to the natural min- erals. C. Geitner 8 also produced crystals of Ni 3 S 4 by heating metal- lic nickel with sulphurous acid or a solution of nickel sulphite under pressure to 200°. E. Weinschenk 9 heated solutions of cobalt or nickel salts with ammonium sulphocyanate to 180° in a sealed tube and so produced crystalline NiS or CoS, respectively. T. Hiortdahl 10 1 The Sudbury polydymite is very nearly N^FeSs. 2 There is also a variety containing much nickel replacing cobalt. Bismutosmaltite, Co(AsBi) 3 , is a related mineral. 3 Another nickel-iron sulphide has been called gunnarite. Its formula is near FezNisSg. Still another, akin to pentlandite, is the incompletely described heazlewoodite. 4 On maucherite, see F. Grinding, Centralbl. Min., Geol. u. Pal., 1913, p. 225. On temiskamite, T. L. Walker, Am. Jour. Sci., 4th ser., vol. 37, 1914, p. 170. Palmer’s work is in Econ. Geology, vol. 9, 1914, p. 664. 6 A similar sulphide, with bismuth partly replacing antimony, has been named kallilite. 6 See L. Bourgeois, Reproduction artificielle des mindraux, p. 35, for old instances. Also A. Brand, Zeitschr. Kryst. Min., vol. 12, 1887, p. 234, on breithauptite. i Annales chim. phys., 3d ser., vol. 32, 1851, p. 129. 3 Liebig’s Annalen, vol. 129, 1864, p. 350. 9 Zeitschr. Kryst. Min., vol. 17, 1890, p. 497. 10 Compt. Rend., vol. 65, 1867, p. 75. Jaipurite is also known as syepoorite. METALLIC ORES. 693 also produced jaipurite by fusing cobalt sulphate with barium sul- phide and common salt. These scanty data show that the minerals of this group may be produced in either the wet or the dry way, and their natural occur- rences point to the same conclusion. Millerite, for instance, forms beautiful tufts of slender, hairlike needles in geodes lined with crys- tals of dolomite. Specimens of this kind are familiar objects to col- lectors of minerals. Millerite is also reported by Des Cloizeaux 1 as found in the coal measures of Belgium, and he mentions linnseite in coal from Glamorganshire, Wales. On the other hand, as J. H. L. Vogt 2 has shown, the nickeliferous pyrrho tites are often, if not always, distinct segregations from molten magmas. On this subject, however, controversy still reigns, and especially with reference to the nickel ores of Sudbury, Canada. Here the ores are chiefly pyrrho- tite with admixtures of pentlandite, a certain amount of chalcopyrite being also present. The matrix is norite, although the earlier observers termed it diorite. Their magmatic origin has been advo- cated by R. Bell , 3 H. B. von Foullon , 4 T. L. Walker , 5 A. P. Coleman , 6 D. H. Browne , 7 and others. A. E. Barlow , 8 for example, repeatedly speaks of the “nickel-bearing eruptive.” Browne compares the occurrences at Sudbury with the phenomena observed in cooling a copper-nickel matte, in which the copper sulphides concentrate along the margins of the mass, and the nickel sulphides at the center. This arrangement of ores, chalcopyrite near the wall rock, then pyr- rhotite carrying nickel, and finally nickel sulphide, is the order observed at Sudbury. R. Beck , 9 C. W. Dickson , 10 and W. Campbell and C. W. Knight , 11 on the other hand, have argued strongly in favor of a secondary origin of these ores — a deposition from circulating solutions . 12 A similar view is expressed by F. W. Voit 13 concerning the nickel ores 1 Bull. Soc. min., vol. 3, 1880, p. 170. 2 Zeitschr. prakt. Geologie, 1893, pp. 125, 357. 3 Bull. Geol. Soc. America, vol. 2, 1890, p. 125. Another paper by Bell, on Sudbury, appears in Ann. Rept. Geol. Survey Canada, 2d ser., vol. 5, F, 1890-91. 4 Jahrb. K.-k. geol. Reichsanstalt, vol. 42, 1892, p. 223. The nickel ores of Schweiderich, Bohemia, are described as analogous to those of Sudbury. e Quart. Jour. Geol. Soc., vol. 53, 1897, p. 40. e Bull. Geol. Soc. America, vol. 15, 1904, p. 551. In Rept. Ontario Bur. Mines, 1904, pt. 1, p. 192, Coleman has a long paper on the “Northern Nickel Range.” The report of the same bureau for 1905, pt. 3, contains a monograph by Coleman on the Sudbury ores. A later paper by Coleman is in Jour. Geology, vol. 51, 1907, p. 759. 7 School of Mines Quart., vol. 16, 1895, p. 297; and Econ. Geology, vol. 1, 1906, p. 487. 8 Econ. Geology, vol. 1, 1906, pp. 454, 545. 8 The nature of ore deposits, Weed’s translation, p. 41. w Trans. Am. Inst. Min. Eng., vol. 34, p. 3, 1904. See also Jour. Canadian Min. Inst., vol. 9, 1906, p. 236. 11 Eng. and Min. Jour., vol. 82, 1906, p. 909. These authors base their opinions on the microscopic struc- ture of the pyrrhotite. 12 Other memoirs upon Sudbury and its ores are by J. EL Collins, Quart. Jour. Geol. Soc., vol. 44, 1888, p. 834; J. Gamier, M&n. Soc. ing6n. civils (France), vol. 44, p. 239; E. R. Bush, Eng. and Min. Jour., vol. 57, 1904, p. 245; T. L. Walker, Am. Jour. Sci., 3d ser., vol. 47, 1894, p. 312; F. W. Clarke and C. Catlett, Bull. U. S. Geol. Survey No. 64, 1890, p. 20; S St. Clair, Min. and Sci. Press, vol. 109, 1914, p. 248; and L. P. Silver, Canadian Min. Rev., vol. 21, 1902, p. 207. 13 Jahrb. K.-k. geol. Reichsanstalt, vol. 50, 1900, p. 717. 694 THE DATA OF GEOCHEMISTRY. of Dobschau, Hungary. Here the arsenides of nickel occur in a carbonate gangue at or near contacts of diorite. At Mine La Motte, Missouri, linnseite is found with lead and copper ores in bodies which C. R. Keyes 1 describes as metasomatic replacements in limestone. Small quantities of nickel are shown in analyses of the adjacent granites. At the Gap mine, in Lancaster County, Pennsylvania, pyrrho tite and chalcopyrite occur with secondary millerite in an amphibolite, which J. F. Kemp 2 thinks is an altered gabbro or norite. This deposit Kemp regards as originally magmatic. In the serpentines of Malaga, Spain, according to F. Gillman, 3 niccolite is found, altered to silicates of nickel at the surface, but associated with chro- mite and augite in the norites below. Here again a magmatic origin is indicated. The nickeliferous pyrrhotites of the southern Schwarz- wald are regarded by E. Weinschenk 4 * as not magmatic. Near Lake Temiskaming, Ontario, an extraordinary group of deposits of associated cobalt, nickel, arsenic, and silver ores was discovered in 19 03. 5 In this district native silver and native bis- muth are found, together with niccolite, chloanthite, smaltite, miHer- ite, cobaltite, argentite, dysorasite, pyrargyrite, tetrahedrite, arseno- pyrite, etc., in relations which are interpreted by Miller as suggesting a deposition from heated waters, which latter were “ probably associated with the post-Middle Huronian diabase and gabbro eruption.’ ’ According to Miller, the deposits are analogous to those of Annaberg, Saxony, and Joachimsthal, Bohemia, which are classical localities for cobalt and nickel minerals. The original source of the Temiskaming ores has not yet been clearly determined. They may represent a leaching of the accompanying eruptive rocks, or they may have been brought from below; at all events, they are not igneous segregations. 6 By oxidation or carbonation the sulphides and arsenides of nickel and cobalt are transformed into sulphates, arsenates, carbonates, oxides, etc. Morenosite, NiS0 4 .7H 2 0; bieberite, CoS0 4 .7H 2 0; the arsenates, roselite, erythrite, annabergite, forbesite, and cabrerite; the carbonates sphserocobaltite, zaratite, and remingtonite ; the oxide bunsenite; and the hydroxides asbolite, heubachite, heterogenite, transvaalite, etc., are among these products of alteration. Bunsenite, NiO, was prepared artificially by J. J. Ebelmen, 7 through the action 1 Missouri Geol. Survey, vol. 9, pt. 4, 1896, p. 82. 2 Trans. Am. Inst. Min. Eng., vol. 24, 1894, p. 620. 3 Trans. Inst. Min. and Met. (London), vol. 4, 1896, p. 159. 4 Zeitschr. prakt. Geologie, 1907, p. 73. 6 See the reports by W. G. Miller, Kept. Ontario Bur. Mines, 1904, pt. 1, p. 96; 1905, pt. 2. Also in Eng. and Min. Jour., vol. 76, 1903, p. 888. 6 These ores have recently been studied microscopically by W. Campbell and C. W. Knight (Econ. Geology, vol. 1, 1906, p. 767), who find that smaltite was first formed, then niccolite, then calcite, with argentite, native silver, and native bismuth later. 7 Compt. Rend., vol. 33, 1851, p. 525. METALLIC ORES. 695 of lime on fused nickel borate. Ferrieres and Dupont 1 also ob- tained it by heating nickel chloride to redness in a current of steam. Neither process seems to bear any close relation to the observed occurrences of bunsenite in nature. Asbolite, or earthy cobalt, is an indefinite mixture of manganese and cobalt hydroxides, and has some significance as a workable ore. 2 This association of cobalt and manganese is not uncommon, and many manganese ores contain more or less cobalt. The hydrous silicates of nickel form a distinct class of ores, differ- ing genetically from the sulphides. They are found in connection with serpentine or other hydromagnesian rocks, and in some instances, if not always, they represent concentrations from peridotitic magmas, and especially from nickeliferous olivine. At Riddles, Oregon, for example, the parent rock is a saxonite or harzburgite, containing, as shown by my own analysis, 3 0.10 per cent of NiO. The olivine separated from the rock contained 0.26 per cent; and from this min- eral the nickel silicates were doubtless formed. Similar silicate ores are found in North Carolina; 4 at Revda in the Urals; at Franken- stein, Prussian Silesia, in serpentine; and at Mount Avala, Servia, with mercurial minerals. The most important deposits, however, are in New Caledonia, 5 where asbolite also occurs. Chromite and vari- ous hydromagnesian minerals are generally associated with the nickel ores. These silicates are rarely, if ever, found as definite mineral species, although they have been described as such. Genthite appears to be H 4 Mg 2 Ni 2 (Si0 4 ) 3 .4H 2 0, and connarite is near H 4 Ni 2 Si 3 O 10 . An- other silicate from New Caledonia, called nepouite, 6 has been given the formula (NiMg) 3 Si 2 0 7 .2H 2 0. Alipite, desaulesite, garnierite, nou- meite, pimelite, refdanskite, and rottisite are uncertain substances, mixtures of nickel silicates with magnesian compounds and free silica. The following analyses will serve to illustrate the variable composition of these ores: 1 See L. Bourgeois, Reproduction artiflcielle des mindraux, p. 51. 2 As at Mine Lamotte, Missouri, and in New Caledonia. On the New Caledonia cobalt ores, see G. M. Colvocoresses, Eng. and Min. Jour., vol. 76, 1903, p. 816, and A. Liversidge, Minerals of New South Wales, pp. 275 et seq. 3 F. W. Clarke and J. S. Diller, Bull. U. S. Geol. Survey No. 60, 1890, p. 21. See also, with regard to this locality, A. R. Ledoux, Canadian Min. Rev., vol. 2^, 1901, p. 84; W. L. Austin, Proc. Colorado Sci. Soc., vol. 5, 1898, p. 173; and H. B. von Foullon, Jahrb. K.-k. geoi. Reichsanstalt, vol. 42, 1892, p. 223. Von Foullon also describes the deposits at Revda, Frankenstein, and Mount Avala. A later report on the Riddles ores, by G. F. Kay, appears in Bull. U. S. Geol. Survey No. 315, 1907, p. 120. 4 See H. J. Biddle, Mineral Resources U. S. for 1886, U. S. Geol. Survey, 1887, p. 170. The mother rock here is dunite. See also A. E . Barlow, Jour. Canadian Min. Inst. , vol. 9, 1906, p. 303. Barlow regards these ores as formed by the leaching of the peridotite. 6 See A. Liversidge, Minerals of New South Wales, p. 275; J. Gamier, Compt. Rend., vol. 86, 1878, p. 684; D. Levat, M6m. Assoc, frang. av. sci., 1887, p. 534; and F. D. Power, Trans. Inst. Min. Met., vol. 8, 1900, p. 427. Liversidge gives several analyses of garnierite and noumeite. See also J. S. Leckie, Jour. Canadian Min. Inst., vol. 6, 1903, p. 169. 6 E. Glasser, Compt. Rend., vol. 143, 1906, p. 1173. Also Annales des mines, 10th ser., vol. 4, 1904, p. 448. 696 THE DATA OF GEOCHEMISTRY. Analyses of nickel silicates. A. From Riddles, Oregon. Analysis by F. W. Clarke, Bull. U. S. Geol. Survey No. 60, 1890, p. 21. B. From Riddles. Analysis by Hood, Mineral Resources U. S. for 1882 ,U. S. Geol. Survey, 1883, p. 404. Probably this sample was dried at or near 100° before analyzing. C. D, E. From New Caledonia. Analyses by A. Liversidge, Minerals of New South Wales, pp. 275-280. Liversidge gives 19 analyses in all, including several by Leibius. A B c D E Si0 2 44. 73 } 1.18 27. 57 10. 56 8. 87 6. 99 40. 55 } 1.33 29. 66 21. 70 } 7.00 48. 25 } .55 J 14.60 16. 40 10. 95 8. 82 38. 35 .40 .15 32. 52 10. 61 6. 44 11. 53 50. 15 .57 Trace. 10. 20 17. 43 11. 28 10. 37 A1 2 0, Fe 2 0 3 NiO MgO H 2 0 at 100° H 2 0 redness 99. 90 100. 24 99. 57 100. 00 100. 00 In one respect all the ores of nickel seem to agree. Their magmatic associate is always a subsilicic rock, such as norite, peridotite, or sometimes diabase or diorite. In no case are they clearly shown to have originated from persilicic magmas. CHROMIUM. Like nickel, chromium is widely diffused in the subsilicic rocks, the average proportion found in 256 analyses of igneous rocks in the laboratory of the United States Geological Survey being 0.05 per cent of Cr 2 0 3 . The native metal has not been found, nor are any ter- restrial sulphides of chromium known, although the mineral daubree- lite, FeCr 2 S 4 occurs in some meteoric irons. The one important ore of chromium is chromite, or chromic iron. There are also the lead chromates, mentioned in a previous section of this chapter; the two sulphates knoxvillite and redingtonite; and the silicates represented by chromiferous garnet, diopside, mica, and tourmaline. The clay- like silicates avalite, milosin, and alexandrolite also contain chromium as an essential constituent. 1 Dietzeite, from the Chilean niter beds, is an iodate and chromate of calcium. Of all these species chromite alone needs any further consideration. In the chapter upon rock-forming minerals chromite was described as a member of the spinel group. Its ideal formula is FeCr 2 0 4 , but it rarely, if ever, is found in a state of even approximate purity. It commonly contains isomorphous admixtures of other spinels, whose presence is revealed in the analyses. The following examples will serve to illustrate its variations : 2 1 See S. M. Losanitsch, Ber. Deutsch. chem. Gesell., vol. 28, 1895, p. 2631. 2 See also table in Chapter X, on rock-forming minerals, p. 344. Two of the analyses there given are re- peated here. METALLIC ORES. 697 Analyses of chromite. A. From Price Creek, North Carolina. Analysis by C. Baskerville. B. From Corundum Hill, North Carolina. Baskerville. C. From Corundum Hill. Analysis by T. M. Chatard, in the laboratory of the United States Geological Survey. D. From Webster, North Carolina. Analysis by H. W. Foote. Variety named mitchellite. For A, B, and D, see J. H. Pratt and J. V. Lewis, North Carolina Geol. Survey, vol. 1, p. 369, 1905. Magnochromite is another name for a magnesian chromite. E. From Tampadel, lower Silesia. Analysis by Laszczynski. Described by H. Traube, Zeitschr. Deutsch. geol. Gesell., vol. 46, p. 50, 1894. A B c D E Cr 2 0 3 59. 20 57. 20 45. 94 39. 95 41. 23 ALO, . 7. 15 7. 82 2. 51 29. 28 24. 58 FeO 25. 02 25. 68 42. 90 13. 90 19.04 MnO .92 .69 .84 .58 CoO,NiO . 16 CuO .40 MgO 4. 42 5. 22 2. 81 17. 31 14. 77 CaO 1. 40 Si0 2 3. 20 2. 80 3. 20 TiOo .36 p„o! .12 A 2 W 5* • • • 99. 91 99. 41 100. 64 100. 44 100. 20 Chromite was first produced artificially by J. J. Ebelmen , 1 who fused chromic oxide, ferric oxide, and boric oxide together, with a little tartaric acid added to reduce the iron to the ferrous state. By adding small amounts of alumina and magnesia the composition of the product was made to vary, like that of the natural mineral. J. Clouet 2 also prepared chromite by essentially the same process, only with trifling differences in detail. S. Meunier 3 obtained chromite by oxidizing an alloy of iron and chromium, and suggested that such an alloy might be brought up from great depths and oxidized by vapors near the surface of the earth. There is no direct evidence, however, to show that such an alloy exists in nature, and the common presence of chromite in meteorites indicates a different origin for the mineral. Chromite is almost exclusively found in subsilicic rocks, such as peridotites and the serpentines derived from them. Its occurrence in placers as a detrital mineral is of course not excluded by this statement. It is distinctly a magmatic mineral, as Vogt and others have shown . 4 1 Annales chim. phys., 3d ser., vol. 22, 1848, p. 228. 2 Idem, 4th ser., vcl. 16, 1869, p. 90. s Compt. Rend., vol. 110, 1890, p. 424. * See J. H. L. Vogt, Zeitschr. prakt. Geologie, 1894, with special reference to Norwegian deposits. On chromite at Kraubath, Styria, see F. Ryba, idem, 1900, p. 337; and in Asia Minor, K. E. Weiss, idem, 1901, p. 250. R. Helmhacker (Min. Industry, 1895, p. 94) describes Austrian localities. On chromite in Mary- land, see W. Glenn, Trans. Am. Inst. Min. Eng., vol. 25, 1896, p. 481; and on Canadian ores, the same author, in Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1896, p. 261. M. Penhale (Min. Industry, 1895, p. 92) also describes Canadian chromite. The chromite of North Carolina is discussed by J. H. Pratt in Am. Jour. Sci., 4th ser., vol. 7, p. 281 ; and Trans. Am. Inst. Min. Eng., vol. 29, 1899, p. 17. See also J. H. Pratt and J. V. Lewis, North Carolina Geol. Survey, vol. 1, 1905, p. 369. 698 THE DATA OF GEOCHEMISTRY. MOLYBDENUM AND TUNGSTEN. Although, molybdenum and tungsten are members of the same elementary group with chromium, their geologic affinities are not the same. Chromium, as we have seen, is found characteristically in subsilicic rocks, while molybdenum and tungsten are commonly asso- ciated with granite. Neither metal is found free in nature, nor is either one widely diffused. The principal ore of molybdenum is the sulphide, molybdenite, MoS 2 . The molybdate of lead, wulfenite, has already been described. Calcium molybdate, powellite, is a rare mineral, and natural molyb- dates of cobalt and magnesium are imperfectly known. Molybdic ocher is a common oxidation product of molybdenite. It is, as shown by W. T. Schaller, 1 a hydrous ferric molybdate, Fe 2 (Mo0 4 ) 3 .7§H 2 0. Artificial molybdenite has been prepared by A. de Schulten. 2 Potassium carbonate was fused with sulphur, and molybdic oxide was gradually added, in successive portions, to the melt. Crystals of molybdenite were thus formed. Powellite, also, has been made by L. Michel, 3 who heated sodium molybdate, calcium chloride, and sodium chloride together. A little sodium tungstate was added to the mixture, in order to reproduce more exactly the natural mineral, in which some tungsten is found. As a rule, molybdenite is a fairly pure compound, although Michel 4 has described a variety containing 28.37 per cent of bismuth. It was evidently a mixture of molybdenite with bismuthinite. Bis- muth is a not infrequent associate both of molybdenite and of wolfram. At Crown Point, Washington, according to A. R. Crook, 5 large quantities of molybdenite are found in a quartz vein in granite. At Cooper, Maine, as described by G. O. Smith, 6 the molybdenite is found in pegmatite dikes and also in the adjacent granite. It may be either an original mineral or an impregnation; probably, says Smith, the latter. In Canada molybdenite occurs under a variety of conditions, often in granite, but also, according to J. W. Wells, 7 in veins cutting limestone, and associated with pyroxene, calcite, quartz, mica, pyrite, etc. The mineral was found embedded some- times in pyroxene and sometimes in pyrrho tite, and Wells further- more reports it in veins through pyroxenite. The nature and origin of these unusual associations remain , to be determined. They probably represent contact metamorphism. 1 Am. Jour. Sci.,4th ser., vol. 23, 1907, p. 297. Work done in the laboratory of the United States Geo- logical Survey. 2 Geol. Foren. Forhandl., vol. 11, 1889, p. 401. 3 Bull. Soc. min., vol. 17, 1894, p. 612. 4 Idem, vol. 22, 1899, p. 29. 6 Bull. Geol. Soc. America, vol. 15, 1904, p. 283. 6 Bull. U. S. Geol. Survey No. 260, 1905, p. 197. 7 Canadian Min. Rev., vol. 22, 1903, p. 113. METALLIC ORES. 699 The ores of tungsten are by no means numerous. In addition to stolzite, which was mentioned among the ores of lead, there are the tungstate of iron, wolframite, or ferberite when the compound is entirely free from manganese; the tungstate of manganese, hubner- ite; calcium tungstate, scheelite; the copper salt, cuprotungstite ; and an alteration product, tungstic ocher. Of these, wolframite, hub- nerite, and scheelite are economically important, and all three have been prepared artificially. N. S. Manross 1 obtained scheelite by fusing sodium tungstate with calcium chloride. A. Cossa 2 also prepared it by fusing the amor- phous compound, CaW0 4 , with common salt. H. Debray 3 heated amorphous calcium tungstate with lime in a current of gaseous hydro- chloric acid, and so effected its crystallization. He also heated a mix- ture of tungstic oxide and ferric oxide in the same gas, forming in that way both wolframite and magnetite. Some of the tungstic acid crystallized at the same time. A. Geuther and E. Forsberg 4 pro- duced wolframite and its manganesian varieties by fusing sodium tungstate with ferrous chloride, or with the mixed chlorides of iron and manganese. L. Michel, 5 by fusing sodium tungstate and sodium chloride with the chlorides of calcium, manganese, iron, or lead, obtained scheelite, hlibnerite, wolframite, and stolzite, respectively. Wolframite is a frequent companion of tin ores, especially in greisen, the cassiterite and the tungsten minerals having developed in much the same way. In the Cornish tin mines wolframite is an annoying impurity, and it also occurs, according to J. D. Irving, 6 in the Etta tin district of the Black Hills. Near Lead City, in the same region, however, Irving found wolframite in magnesian limestone, where it had apparently been formed by metasomatic replacement. This occurrence was secondary, the primary wolframite being found in quartz veins cutting granite rocks. At Osceola, Nevada, hubnerite is abundant, with some scheelite, in veins of white quartz in a porphy- ritic granite. 7 The Tungsten deposits of the Dragoon Mountains, Arizona, are of the same character, 8 the ore being principally hiib- nerite, with scheelite and some wolfram. The tungsten mine at Trum- bull, Connecticut, where wolframite, scheelite, and tungstic ocher are found, has been described by A. Gurlt 9 and W. H. Hobbs. 10 In the 1 Liebig’s Annalen, vol. 81, 1852, p. 243. 2 Cited by L. Bourgeois, Reproduction artiflcielle des mineraux, p. 172. 3 Compt. Rend., vol. 55, 1862, p. 287. * Liebig’s Annalen, vol. 120, 1861, p. 270. 6 Bull. Soc. min., vol. 2, 1879, p. 142. 6 Trans. Am. Inst. Min. Eng., vol. 31, 1901, p. 683. See also J. D. Irving and S. F. Emmons, Prof. Paper U. S. Geol. Survey No. 26, 1904, p. 163. 7 See F. B. Weeks, Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 6, 1901, p. 319; and F. D. Smith, Eng. and Min. Jour., vol. 73, 1902, p. 304. 8 See W. P. Blake, Trans. Am. List. Min. Eng., vol. 28, 1898, p. 543, and F. Rickard, Eng. and Min. Jour., vol. 78, 1904, p. 263. 9 Trans. Am. Inst. Min. Eng., vol. 22, 1893, p. 236. 10 Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 2, 1902, p. 13. 700 THE DATA OF GEOCHEMISTRY. Sierra de Cordoba, Argentina, according to G. Bodenbender , 1 the wolframite is again in quartz veins in granite, and molybdenite is sometimes present also. These illustrations of tungsten occurrences are ample for present purposes. THE PLATINUM METALS. The metals platinum, iridium, osmium, palladium, rhodium, and ruthenium form a well-defined natural group of elements, which are found associated with one another, and in less degree with iron, nickel, chromium, etc. With two exceptions the platinum metals occur native, or in alloys, which vary much in composition, and have received many specific names. The two exceptions are laurite, ruthenium sulphide, RuS 2 ; and sperrylite, platinum arsenide, PtAs 2 . The native metals and recognized alloys are as follows: Native platinum. Native iridium and platiniridium. Native palladium, isometric. Allopalladium, rhombohedral. T . . . fNevyanskite, over 40 per cent Ir. IndosmmeL. J . .. ’ A T , [Siserskite, 30 per cent Ir, or less. Palladium gold. 2 Rhodium gold. 2 The list might be extended by subdivision, but the increase in names would be meaningless. The following selected analyses fairly represent the great variations in native platinum : 3 1 Zeitschr. prakt. Geologie, 1894, p. 409. On the tungsten ores of Colorado, see W. Lindgren, Econ. Geology, vol. 2, 1907, p. 453, and R. D. George, First Kept. Colorado Geol. Survey, 1908, p. 7. On tungsten deposits in the Cceur d’Alene region, Idaho, see H. S. Auerbach, Eng. and Min. Jour., vol. 86, 1908, p. 1146. 2 See section on gold, ante, p. 644. s See J. F. Kemp, Bull. U. S. Geol. Survey No. 193, 1902, for a full collection of analyses, both of platinum and iridosmine. Other analyses by W. J. Martin, jr., appear in Sixteenth Arm . Rept. U. S. Geol. Survey, pt. 3, 1895, p. 633. See also Dana’s System of mineralogy, 6th ed., pp. 26, 27. Recent analyses of Uralian platinum by L. Duparc and H. C. Holtz are in Min. pet. Mitt., vol. 29, 1910, p. 498. G. P. Merrill (Proc. Nat. Acad., vol. 1, 1915, p. 429) reports the presence of Pt, Pd, Ir, and Ru in meteorites. METALLIC ORES. 701 Analyses of native platinum. A. From Choco, Colombia. Analysis by H. Sainte-Claire Deville and H. Debray, Annales chim. phys., 3d ser., vol. 56, 1859, p. 449. B. From California. Deville and Debray. C. Nugget found near Plattsburg, New York, of 54 per cent chromite and 46 per cent metallic platinum. Analysis of the platinum by P. Collier, Am. Jour Sci., 3d ser., vol. 21, 1881, p. 123. D. From Nizhni Tagilsk, Urals, Deville and Debray. E. From Nizhni Tagilsk, blackish magnetic grains. Analysis by J. von Muchin (commonly but erro- neously quoted as Minchin), cited, with other analyses, by N. von Kokscharof, Materialien zur Mineralogie Russlands, vol. 5, 1866, p. 186. F. Granite Creek, British Columbia. Nonmagnetic portion of sample. Analysis by G. C. Hoffmann, Trans. Roy. Soc. Canada, vol. 5, sec. 3, p. 17. G. Magnetic portion of F. Analysis by Hoffmann. H. From Condado, Minas Geraes, Brazil. Analysis by E. Hussak, Zeitschr. prakt. Geologie, 1906, p. 284. For a paper by Hussak on platinum and palladium in Brazil, see Sitzungsb. Akad. Wien, vol. 113, Abth. 1, 1904, p. 379. A B c D E F G H Pt 86. 20 .85 85. 50 1. 05 82. 81 .63 76. 40 4. 30 68. 95 1. 34 Trace. .21 3. 30 68. 19 1. 21 78. 43 1.04 72. 96 .88 Undet. 21. 82 Undet. Ir Os Pd .50 1.40 1.00 .60 7. 80 .95 .60 1. 00 .80 1. 40 6. 75 1. 10 3. 10 .29 1.40 .30 .40 4. 10 11. 70 .50 .26 3. 10 .09 1. 70 Rh Au Cu .40 11.04 1.59 18. 93 3. 75 3. 09 7. 87 14. 62 3. 89 9. 78 3. 77 Fe Trace. Iridosmine AIoOq 1. 95 .07 .03 CaO MgO Insoluble .42 Sand .95 2. 95 1. 40 Chromite 1. 95 1. 27 100. 25 101. 15 100. 32 100. 50 98. 07 100. 29 99. 97 96. 08 In another sample of Uralian platinum, A. Terreil 1 found 0.75 per cent of nickel. A remarkable nugget from the river Approuague, French Guiana, gave A. Damour 2 41.96 Pt, 18.18 Au, 18.39 Ag, and 20.56 per cent Cu. This sample is altogether exceptional. The subjoined analyses are of native iridium, platiniridium, and iridosmine. 1 Compt. Rend., vol. 82, 1876, p. 1116. 2 Idem, vol. 52, 1861, p. 688. 702 THE DATA OF GEOCHEMISTRY. Analyses of native iridium, etc. A. Native iridium. Nizhni Tagilsk, Urals. B. Platiniridium, probably from Brazil. Analyses A and B by Svanberg, Berzelius’s Jahresb., vol- 16, 1834, p. 205. C. Iridosmine from Colombia. D. Iridosmine from the Urals. E. iridosmine from the Urals. Analyses C, D, and E by Deville and Debray, Annales chim. phys., 3d ser., vol. 56, 1859, pp. 481, 482. A B C D E Ir 76. 80 19. 64 27. 79 55.44 Trace. .49 6. 86 70. 40 .10 17. 20 77. 20 1. 10 21. 00 43. 94 .14 48. 85 Pt Os Pd .89 Rh 12. 30 None. .50 .20 Trace. 1. 65 4. 68 .11 .63 Ru Cu 1. 78 3.30 4. 14 Fe 99. 11 98. 02 100. 00 100. 00 100. 00 The indefinite character of these natural alloys seems to be per- fectly evident. The platinum and iridosmine of commerce are almost entirely from detrital or placer deposits, but their primary geologic affinities are subsilicic. That is, the ores are associated with chromite and other products of the decomposition of peridotic rocks, from which they were undoubtedly derived. Chromite has been repeatedly observed adherent to or interpenetrating platinum nuggets, and A. Inostran- zeff 1 has reported platinum in place in the dunite, or rather serpen- tine, of Mount Solovief in the Urals. On the Tulameen River, British Columbia, according to J. F. Kemp , 2 the mother rock is also dunite, and grains of platinum are found with both chromite and olivine adhering to them. Even the serpentine of this region yields traces of platinum upon careful assay. The black sands of the Pacific coast, from British Columbia southward to California, contain platinum, and also iridosmine, and their origin is peridotic . 3 Accord- ing to H. Bancroft , 4 platinum is found in certain peridotite dikes in Clark County, Nevada. On the other hand, L. Duparc , 5 6 who has devoted much study to Uralian platinum, reports its association with pyroxenite and gabbro. 1 See English translation from the Russian in Bull. U. S. Geol. Survey No. 193, 1902, p. 76. 2 Bull. U. S. Geol. Survey No. 193, 1902. A brief monograph on the geologic relations and distribution of platinum. a See D. T. Day, Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 6, 1899, p. 265. Also Day and R. H. Richards, Bull. U. S. Geol. Survey No. 285, 1906, p. 150. In Trans. Am. Inst. Min. Eng., vol. 30, 1900, p. 702, Day has a memoir on platinum in North America. * Bull. U. S. Geol. Survey No. 430, 1910, p. 192. 6 Arch. Sci. phys. nat., 4th ser., vol. 30, 1910, p. 379; and vol. 31, 1911, p. 211. An earlier memoir by Duparc is in vol. 15, 1903, pp. 287, 377, which includes a bibliography of Uralian platinum. See also A. Saytzeff, Zeitschr. prakt. Geologie, 1898, p. 395; C. W. Purington, Trans. Am. Inst. Min. Eng., vol. 29, 1899, p. 3; and R. Spring, Zeitschr. prakt. Geologie, 1905, p. 49. METALLIC ORES. 703 A. Daubree, 1 many years ago, commenting upon the constant association of platinum with olivine rocks and chromite, pointed out the similarity of these rocks to meteorites. Much later, J. M. Davi- son 2 announced the presence of platinum and iridium in the meteoric iron of Coahuila. Still more recently, S. Meunier 3 has discussed this relationship at some length, and argued that, contrary to the usual view, the native platinum and iron of these rocks are not mag- matic, but are introduced as vaporized chlorides and subsequently reduced by heated hydrogen. This mode of introduction and depo- sition Meunier reproduced artificially, but the application of the experiments to meteorites is not quite clear. In a number of cases platinum has been detected in sedimentary or metamorphic rocks. Kemp 4 mentions its occurrence in certain Pennsylvanian shales, and states also that the palladium gold of Brazil is sometimes associated with itabirite. E. Hussak 5 found palladium gold in a contact limestone, and reports the platinum of Brazil not only from olivine rocks, but also from a conglomeritic quartzite. According to J. B. Jaquet, 6 platinum occurs near Broken Hill, Australia, in ironstone, ferruginous claystone, and decomposed gneiss. It is also said to be present in the ash of certain Australian coals. 7 F. Sandberger 8 identified platinum in limonite nodules from Mexico. In an altered limestone lens in Sumatra, L. Hundeshagen 9 found platinum up to 6 grams per metric ton. The metal was in wollastonite, which formed from 85 to 88 per cent of the rock, with 12 to 14 per cent of grossularite. Hundeshagen regards this occur- rence as due to the introduction of hot solutions containing gold, silver, and platinum into the metal-bearing rock. Natural solutions of platinum, however, do not appear to have been observed; and its solubility in natural solvents is undetermined. Possibly the plati- niferous quartz from the south island of New Zealand, recently de- scribed by J. B. Bell, 10 had a similar origin. The quartz veins, how- ever, were near altered magnesian eruptives, in which no platinum was found. The occasional presence of platinum in sulphide ores has long been known, although it has attracted serious attention only within recent 1 Compt. Rend., vol. 80, 1875, p. 707. 2 Am. Jour. Sci., 4th ser., vol. 7, 1899, p. 4. 3 Compt. rend. VII Cong. geol. intemat., 1897, p. 157. 4 Bull. U. S. Geol. Survey No. 193, 1902. 6 Zeitschr. Kryst. Min., vol. 42, 1906, p. 399. G Rec. Geol. Survey, New South Wales, vol. 5, 1896-1898, p. 33. See also J. C. H. Mingaye, Ann. Rept. Dept. Mines, New South Wales, 1889, p. 249. 7 See Seventeenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1896, p. 282. 8 Neues Jahrb., 1875, p. 625. 9 Trans. Inst. Min. and Met., vol. 13, 1903-4, p. 550. 19 Econ. Geology, vol. 1, 1906, p. 749. 704 THE DATA OF GEOCHEMISTRY. years. E. Gueymard 1 found it in tetrahedrite, in a gangue of dolo- mite, quartz, and barite, at Chapeau Mountain, in the French Alps. The country rock was a metamorphic limestone. H. Rossler 2 de- tected both platinum and palladium in silver bullion; and H. Vogel 3 reports its presence in the metallic ores of Boitza, Transylvania. Much more striking, however, is the presence of platinum in the sulphide ores of Sudbury, Canada. Here it is found as the arsenide, sperrylite, 4 associated with nickeliferous pyrrhotite and chalcopyrite, but most intimately with the latter. F. W. Clarke and C. Catlett, 5 however, showed its presence in massive polydymite. At the Ram- bler mine, in Wyoming, both platinum and palladium are found in covellite, in ores derived from diorite. 6 Here, also, sperrylite has been identified. 7 At this locality palladium appears to be more abundant than platinum, but its mode of combination is as yet unde- termined. Sperrylite has furthermore been found by J. Catharinet 8 in the pegmatite of Copper Mountain, British Columbia. One small crystal was embedded in biotite. Platinum is also present, according to C. W. Dickson, 9 in chalcopyrite from the Key West mine, Bunker- ville, Nevada; but sperrylite could not be detected. J. H. L. Vogt 10 found platinum to be present in the nickeliferous pyrrhotites of Nor- way, and R. W. Brock 11 discovered traces, of it in sulphide-bearing quartz at the Mother Lode claim, Yale district, British Columbia. These occurrences have led to much searching after platinum in copper and nickel ores, and the search is likely to be occasionally fruitful. 12 The presence of platinum in sulphide ores near Broken Hill has been reported by J. C. H. Mingaye. 13 In plumb ojarosite from Goodsprings, Nevada, R. C. Wells 14 found up to 0.2 per cent of palladium, with a trace of platinum. 1 Compt. Rend., vol. 29, 1849, p. 814. See also Gueymard, Bull. Soc. gdol. France, 2d ser., vol. 12, 1854-55, p. 429, on other occurrences of platinum in the Alps. 2 Liebig’s Annalen, vol. 180, 1875, p. 240. 2 Oesterr. Zeitschr. Berg- u. Hiittenw., vol. 39, p. 32. * See H. L. Wells, Am. Jour. Sci, 3d ser., vol. 37, 1889, p. 67. Sperrylite has since been found by W. E. Hidden (idem, 4th ser., vol. 6, 1898, p. 381), and by Hidden and J. H. Pratt (idem, vol. 6, 1898, p. 467), at two localities in North Carolina, associated with rhodolite garnet. For details concerning Sudbury, see the section on nickel and cobalt, ante, p. 693. 5 Bull. U. S. Geol. Survey No. 64, 1890, p. 20. 6 See W. C. Knight, Eng. and Min. Jour., vol. 72, 1901, p. 845; vol. 73, 1902, p. 696; J. F. Kemp, Cont. Geol. Dept. Columbia Univ., vol. 11, No. 93, 1903; S. F. Emmons, Bull. U. S. Geol. Survey No. 213, 1903, p. 94; and T. T. Read, Eng. and Min. Jour., vol. 79, 1905, p. 985. i H. L. Wells and S. L. Penfield, Am. Jour. Sci., 4th ser., vol. 13, 1902, p. 95. s Eng. and Min. Jour., vol. 79, 1905, p. 127. 9 Jour. Canadian Min. Inst., vol. 8, 1905, p. 192. Memoir on the distribution of the platinum metals in other sources than placers. On platinum and palladium in blister copper, see A. Eilers, Bull. Am. Inst. Min. Eng., No. 78, 1913, p. 999. In graywacke, P. Krusch, Metall u. Erz, vol. 11, 1914, p. 545. 19 Zeitschr. prakt. Geologie, 1902, p. 258. “ Eng. and Min. Jour., vol. 77, 1904, p. 280. i2 According to W. Baragwanath (Bull. Geol. Survey Victoria, No. 20, 1906), platinum is found in the Thomson River copper mine in a hornblende rock rich in chalcopyrite. I® Rec. Geol. Survey New South Wales, vol. 8, 1909, p. 287. 1 4 Work done in the laboratory of the U. S. Geological Survey. On the Goodsprings deposit, see A. Knopf, Bull. U. S. Geol. Survey No. 620-A, 1915. METALLIC OEES. 705 VANADIUM AND URANIUM. Although vanadium and uranium are chemically unlike, they occur together in one of their important ores, and are therefore considered together in this section. Vanadium is a member of the phosphorus group of elements; uranium is more akin to molybdenum and tung- sten, and the two metals are also magmatically opposed. Vanadium is most common in ferromagnesian rocks, while uranium minerals occur more frequently in granites and pegmatites. Vanadium is reckoned among the rarer elements, and yet it is widely diffused. Traces of it are common in iron ores, especially in the titaniferous magnetites, and it is found, when sought for, in rocks of nearly every class. 1 W. F. Hillebrand, 2 in a special investigation, examined 57 igneous rocks, and found vanadium, in most cases, in weighable proportions. The smallest traces were in persilicic rocks, but in subsilicic varieties the amount, reckoned as V 2 0 3 , frequently ran as high as 0.03 to 0.05 per cent. In the ferromagnesian minerals separated from some of the rocks the proportion of vanadium was even higher, in one biotite, for example, reaching 0.127 per cent of V 2 0 3 . Hillebrand also found vanadium in slates and in other sedi- mentary rocks. A composite of 253 sandstones gave 0.003, and another of 498 limestones gave 0.004 per cent of vanadious oxide. H. Sainte-Claire Deville 3 found vanadium in French bauxite, in cryolite, and in rutile. P. Beauvallet 4 detected it in a French clay. In bricks made from a clay found near Sydney, Australia, according to E. H. Bennie, 5 vanadium is present to a perceptible amount. Other Australian clays and shales gave J. C. H. Mingaye 6 similar results. He also found vanadium in the ash of coals and in the oil- bearing shales of Scotland. E. Bechi 7 reports vanadium in clays, schists, and the ashes of plants, 8 and C. Baskerville 9 found it in the ashes of peat from North Carolina. A. Jorissen 10 discovered it in delvauxite, which is a hydrous phosphate of iron. 1 See A. A. Hayes, Proc. Am. Acad. Arts and Sci., vol. 10, 1875, p. 294. Hayes found vanadium in many rocks, and also in the waters of Brookline, Massachusetts. For determinations of vanadium in lavas of Vesuvius and Etna, see L. Ricciardi, Gazz. chim. ital., vol. 13, 1883, p. 259. Scattered deter- minations are numerous. 2 Bull. U. S. Geol. Survey No. 167, 1900, p. 49. See also J. H. L. Vogt, Zeitschr. prakt. Geologie, 1899, p. 274, on the distribution of vanadium in rocks. W. Pollard (Summ. Prog. Geol. Survey Great Britain, 1902, p. 60) has found vanadium in a number of rocks. On vanadium in the Stassfurt salt clay see E . Marcus and W. Biltz, Zeitschr. anorg. Chemie, vol. 68, 1910, p. 91. 3 Annales chim. phys., 3d ser., vol. 61, 1861, pp. 309, 342. See also L. Dieulafait, Compt. Rend., vol. 93, 1881, p. 804. < Compt. Rend., vol. 49, 1859, p. 301. 6 Proc. Roy. Soc. New South Wales, vol. 17, 1883, p. 133. He cites similar examples from other authori- ties. c Rec. Geol. Survey New South Wales, vol. 7, 1903, p. 219. v Atti R. accad. Lincei, 3d ser., vol. 3, 1879, p. 403. c See also E. Demargay, Compt. Rend., vol. 130, 1900, p. 91. o Jour. Am. Chem. Soc., vol. 21, 1899, p. 706. w Annales Soc. gdol. Belgique, vol. 6, 1878-9, p. 41. 97270°— Bull. 616—16 45 706 THE DATA OF GEOCHEMISTRY. A still more remarkable occurrence of vanadium was noted by J. J. Kyle 1 in a lignite from San Rafael, Province of Mendoza, Argentina. The coal yielded only 0.63 per cent of ash, but the latter, upon analy- sis, was found to contain 38.22 per cent of V 2 0 5 , together with sili- cates and sulphates of other metals. In a similar coal, probably from the same region, A. Mourlot 2 obtained 38.5 per cent of V 2 0 5 from the ash; and in another, from Yauli, Peru, Torrico y Meca 3 discovered 38 per cent. The ash of a grahamite from near Page, Oklahoma, analyzed in the laboratory of the United States Geo- logical Survey by R. C. Wells, contained 12.2 per cent of V 2 0 5 . In the ash of an asphalt from Nevada the same chemist found nearly 30 per cent. These ash analyses, taken together with the finding of vanadium in the ashes of wood and peat, suggest that plants have played some part in the concentration of vanadium. Other evidence of similar purport will be cited later. The definite minerals containing vanadium as an essential con- stituent are not very numerous. Some of them, vanadates of lead, such as vanadinite and descloizite, were mentioned in a previous section of this chapter. Volborthite and calciovolborthite are vana- dates of copper, with other bases, and pucherite is a vanadate of bis- muth. Mottramite, a vanadate of copper and lead, found at Alderley Edge, in England, has had some significance as a workable ore. It occurs as an impregnation in Keuper sandstone. 4 A Mexican variety of descloizite, ramirite, 5 has also been commercially exploited. These vanadates, with the exception of mottramite, occur principally in metalliferous veins; and A. Ditte 6 attributes their formation to percolating vanadiferous waters acting on other compounds, most commonly the compounds of lead. The so-called vanadic ocher is doubtful. A sulphovanadate of copper, sulvanite, Cu 3 VS 4 , is found in South Australia. 7 At Minasragra, near Cerro de Pasco, Peru, another sul- phide of vanadium, patronite, is found, associated with pyrite, in a carbonaceous substance resembling a coal but abnormally rich in sulphur. 8 This occurrence may well be correlated with the other 1 Chem. News, vol. 66, 1892, p. 211. 2 Compt. Rend., vol. 117, 1893, p. *46. 3 Abstract from a Peruvian original, in Jour. Chem. Soc., vol. 70, pt. 2, 1896, p. 252. For more details, see D. F. Hewett, Bull. Am. Inst. Min. Eng., 1909, p. 291. * See H. E. Roscoe, Proc. Roy. Soc., vol. 25, 1876, p. 111. 6 See G. de J. Caballero, Mem. Soc. cient. Ant. Alzate, vol. 20, 1903, p. 87. 6 Compt. Rend., vol. 138, 1904, p. 1303. 7 See G. A. Goyder, Jour. Chem. Soc., vol. 77, 1900, p. 1094. 8 See D. F. Hewett, Eng. and Min. Jour., vol. 82, 1906, p. 385; and J. J. Bravo, Inform, y Mem. Bol. Soc. ingen. minas, Lima, vol. 8, 1906, p. 171. For a later and much more complete description of the sulphide, patronite, and its associated minerals, see W. F. Hillebrand, Am. Jour. Sci., 4th ser., vol. 24, 1907, p. 141. The bituminous matrix he names quisqueite. A still later memoir on vanadium deposits in Peru, by Hewett, is in Bull. Am. Inst. Min. Eng., 1909, p. 291. METALLIC ORES. 707 discoveries of vanadium in the ash of coal; and the sulphates, equiva- lent to 13.70 per cent of S0 3 , found by Kyle in his analysis, may show that he too had originally a sulphide to deal with which was oxidized during combustion. Associated with and derived from patronite are the calcium vanadates hewettite, pascoite, and fernandinite, a vana- dium sulphate, minasragrite, and other alteration products. 1 The rare mineral ardennite is a vanadio-silicate of manganese and aluminum. Roscoelite appears to be essentially a muscovite in which vanadium has partly replaced aluminum. 2 It contains about 24 per cent of V 2 0 3 . In a green sandstone from Placerville, Colorado, W. F. Hillebrand 3 found 3.50 per cent of V 2 Q 3 , which was present in a replacement of the original calcareous cement. The green mineral, isolated, contained 12.84 per cent of V 2 0 3 and was apparently a variety of roscoelite, or else a closely related compound. The metal uranium is much less abundantly diffused than vana- dium. It is found in a number of rare minerals — phosphates, arse- nates, sulphates, carbonates, and silicates — which are all of secondary origin. Autunite, a phosphate of uranium and lime, is not uncom- mon in the form of yellow scales on granite or gneiss, but the other species are much less frequently seen. A number of other minerals, samarskite, euxenite, etc., are columbates or tantalates containing uranium, and these are primary constituents of pegmatite. The only uranium ores of any importance are uraninite or pitch- blende and carnotite. Uraninite is found crystallized in pegmatites, and also massive in metalliferous veins, as at Joachims thal, 4 in Bohemia, and Johanngeorgenstadt, in Saxony. It varies much in com- position, so much so that different modifications of it have received different names, such as cleveite, nivenite, broggerite, etc. The fol- lowing analyses, by W. F. Hillebrand, 5 6 will serve to illustrate the variations. 1 On hewettite and pascoite see W. F. Hillebrand, H. E.Merwin, and F. E. Wright, Proc. Am. Philos. Soc., vol. 53, 1914, p. 31. The two other species are described by W. T. Schaller, Jour. Washington Acad. Sci., vol. 5, 1915, p. 7. 2 Bull. U. S. Geol. Survey No. 167, 1900, p. 73. a Bull. U. S. Geol. Survey No. 262, 1905, p. 18. * On the Joachimsthal ores, see Janda, Oesterr. Zeitschr. Berg- u. Hiittenw., vol. 50, p. 283; also J. St8p and F. Becke, Zeitschr. prakt. Geologie, 1905, p. 148. R. Pearce (Proc. Colorado Sci. Soc., vol. 5, 1895, p. 156) has described the occurrence of uraninite in a mine near Central City, Colorado. On uranium ores in German East Africa, see W. Marckwald, Centralbl. Min., Geol. u. Pal., 1906, p. 761. 6 See Bull. U. S. Geol. Survey No. 78, 1891, p. 43, and No. 90, 1892, p. 23, for details; also Bull. No, 220, 1903, pp. 111-114. 22 analyses inall aregiven. On the pitchblende of Joachimsthal see R. Jafle, Zeitschr. prakt. Geologie, 1912, p. 425. 708 THE DATA OF GEOCHEMISTRY. Analyses of uraninite. A. Hale’s quarry, Glastonbury, Connecticut. B. Near Central City or Blackhawk, Colorado. C. Johanngeorgenstadt, Saxony. D. Nivenite, Llano Comity, Texas. E. Broggerite, Annerod, Norway. F. Cleveite, Arendal, Norway. A B C D E F UO, 26. 48 25. 26 22. 33 20. 89 30. 63 41. 71 uo 2 57. 43 58. 51 59. 30 44. 17 46. 13 24. 18 Th0 2 9. 79 None. 6. 69 6. 00 Ce0 2 . .25 .22 None. .34 .18 \ 3.66 Zr0 2 7. 59 None. .34 .06 (La, DiLOo . 13 None. 2. 36 .27 J (Y, Er) 9 0, .20 None. 9.46 1. 11 9. 76 A1 2 0 3 *... .20 Fe 2 0 3 .40 .21 .14 .25 .03 FeO ° .32 PbO 3. 26 .70 6. 39 10. 08 9.04 10. 54 ZnO .44 CuO .17 MnO Trace. . 16 .09 CaO .08 .84 1. 00 .32 .37 1.06 MgO Trace? .17 Trace. .10 Bi 2 0 3 .75 VoO*, Mo0 3 , W0 3 .75 Alkalies Trace. Trace? .31 Traces. .23 so, .19 . 22 .06 .02 As 2 0 6 .43 2. 34 He Undet. .02 Trace. .08 . 17 Undet. H 2 0 .61 1. 96 3. 17 1. 48 .74 1. 23 Si0 2 .16 2. 79 .50 .46 .22 .90 CuFeS 2 . 12 FeS 2 .24 Insoluble .70 1. 47 4. 42 1. 10 99. 49 99. 82 97. 93 98. 28 99. 61 94. 50 From these analyses no single definite formula can be deduced. The uranium, it is clearly seen, exercises a double function, acid and basic, the latter being represented by the radicle uranyl, U0 2 . With this base other bases are variably present — tboria, zirconia, the rare earths, and oxide of lead, sometimes one and sometimes another pre- dominating. There are also impurities of several kinds which can not be clearly distinguished from essential constituents, and some of the variations may be due to incipient alterations. For example, the varying ratios between U0 2 and U0 3 may be ascribed to oxidation, the increase in U0 3 marking stages in the process of transformation of uraninite into gummite, a well-known alteration product of pitch- blende. In gummite, which is a hydrous oxide of uranium 1 plus other bases, with from 61 to 75 per cent of U0 3 , the final transforma- tion of uraninite is seen. From a physical point of view uraninite is an extraordinary min- eral. In it helium was first discovered, and later the radioactive elements polonium and radium. Uranium and its compounds are 1 For analyses of gummite, see H. von Foullon, Neues Jahrb., 1885, pt. 1, Ref., p. 21, and F. A. Genth, Am. Chem. Jour., vol. 1, 1879, p. 89. METALLIC ORES. 709 themselves radioactive, but radium is vastly more so ; and the latter, while distinctly an element so far as its chemical characteristics are concerned, undergoes disintegration, yielding a series of emanations which seems to end in the production of helium. Radioactivity, then, appears to be a phenomenon of atomic decay; but the subject is one which hardly falls within the scope of this treatise. For the present it is enough to say that the chief sources of radium to-day are in the uraninite of Joachimsthal and in carnotite, and that uranium itself is the progenitor of its more highly active companion. Carnotite, which is essentially a vanadate of uranium and potas- sium, but with other bases present also, was first described by C. Friedel and E. Cumenge . 1 It is found as a canary-yellow impregna- tion in sandstone in western Colorado and eastern Utah. The former field has been studied by W. F. Hillebrand and F. L. Ransome , 2 the latter by J. M. Boutwell . 3 An outlying region for carnotite in Rio Blanco County, Colorado, has also been described by H. S. Gale . 4 The following analyses of carnotite, by Hillebrand, will show its general character: Analyses of carnotite. A. Copper Prince claim, Roc Creek, Montrose County, Colorado. B. Yellow Boy claim, La Sal Creek, Montrose County. A B uo 3 54. 89 54.00 v 2 o s 18. 49 18. 05 P 2 0 5 .80 .05 As 2 0 5 Trace. None. ALO, .09 .29 .21 .42 3. 34 1. 86 SrO .02 Trace. BaO .90 2. 83 MgO .22 .14 k 2 o 6. 52 5. 46 Na 2 0 .14 .13 Li 2 0 Trace. Trace. H 2 0- 2. 43 3. 16 H 2 0+ 2. 11 2. 21 PbO .13 .07 CuO . . 15 Trace. Mo0 3 .18 .05 Si0 2 . 15 .20 p None. Ti0 2 .03 C0 2 .56 Insoluble 7. 10 10. 33 98. 46 99. 25 1 Compt. Rend., vol. 128, 1899, p. 532. Tyuyamunite, a recently described mineral, is a calcium carnotite, originally from Siberia but also found in Utah. 1 Bull. U. S. Geol. Survey No. 262, 1905, p. 9. 3 Bull. U. S. Geol. Survey No. 260, 1904, p. 200. * Bull. U.S. Geol. Survey No. 315, 1907, p. 110. Gale (Bull. 340, 1908, p. 258) has also described carnotite from Routt County, Colorado. See also H. Fleck and W. G. Haldane (Rept. State Bur. Mines, 1905-6, p. 47) on the uranium and vanadium deposits of southern Colorado. Bull. U. S. Bureau of Mines No. 70, by R. B. Moore and K. L. Kithil, is essentially a monograph on the ores of vanadium and uranium. The Colorado ores are now being worked as a source of radium. On carnotite from Mauch Chunk, Pennsyl- vania, see E. T. Wherry, Am. Jour. Sci., 4th ser., vol. 33, 1912, p. 574. 710 THE DATA OF GEOCHEMISTRY. With the carnotite a vanadiferous silicate also occurs, which may be akin to roscoelite. Two calcium vanadates, metahewettite and pintadoite, and a vanadate of uranium, uvanite are also present. 1 In the Utah field, as described by Boutwell, not only carnotite, but other vanadates, such as calciovolborthite, are found. In Wildhorse Canyon a black, carbonaceous sandstone also occurs, in which vana- dium is present. This recalls the occurrences of vanadium in coals elsewhere. In the San Rafael Swell the carnotite is found principally on or near the fossil remains of plants, whose organic matter, Bout- well suggests, may have acted as precipitants of vanadium. The same association with fossil wood was also noted by Gale. No sul- phide of vanadium, however, like that of Peru, has yet been identified in this region. Carnotite has also been reported by D. Mawson 2 in the pegmatite of “ Radium Hill,” South Australia. Uranium, like vanadium, has been found in coal. In an anthra- citic bitumen from Sweden, described by A. E. Nordenskiold, 3 the ash contained about 3 per cent of U 3 0 8 , with some nickel oxide and rare earths. In the ash of Swedish “kolm,” a bituminous coal, H. Liebert, 4 * working in C. Winkler’s laboratory, found from 1.68 to 2.87 per cent of U 3 0 8 . An anthracitic mineral from a pegmatite vein in the Saguenay district, Canada, yielded J. Obalski 6 2.56 per cent of uranium, equivalent to 35.43 per cent in the ash. The significance of these occurrences remains to be determined. COLUMBIUM, TANTALUM, AND THE RARE EARTHS. A striking feature in the recent development of chemical indus- tries has been the utilization of rare elements which previously had only scientific interest. The invention of incandescent gas lighting has created a demand for several of these substances, and that reason alone is enough to justify their brief consideration here. Columbium 6 and tantalum are acid-forming elements, whose typical oxides have the formulae Cb 2 0 5 and Ta 2 0 5 . They enter into the composition of a considerable number of minerals, which are found principally in pegmatites. Among these, columbite, tantalite, samarskite, and euxenite are by far the most important. Columbite and tantalite are salts of iron, FeCb 2 0 6 and FeTa 2 0 6 , which com- monly occur more or less isomorphously commingled, often with 1 On metahewettite see Hillebrand, Merwin, and Wright, loc. cit. The two other species are described by F. L. Hess and W. T. Schaller, Jour. Washington Acad. Sci., vol. 4,1914, p.576. On the origin of carnotite see Hess, Econ. Geology, vol. 9, 1914, p. 675. 2 Trans. Roy. Soc. South Australia, vol. 30, 1906, p. 188. 3 Compt. Rend., vol. 116, 1893, p. 677. * See C. Winkler, Zeitschr. Kryst. Min., vol. 37, 1903, p. 287. 6 Jour. Canadian Min. Inst., vol. 7, 1904, p. 245. 6 Known in Germany as niobium. The name columbium has more than 40 years’ priority and refers to the original discovery of the element in a mineral from America. Niobium is etymologically meaningless. METALLIC ORES. 711 manganese partly replacing the iron. Metallic tantalum 1 has recently been utilized as a substitute for the carbon filament in incandescent electric lights, and tantalite is the chief source from which it can be obtained. 2 The supply so far is mainly from Scandinavian localities. Zirconium and thorium are tetrad metals forming oxides of the type R0 2 . They also are found in granitic rocks, and zirconium compounds are almost always present in nepheline syenites. The chief zirconium mineral, zircon, ZrSi0 4 , has already been described in the chapter upon rock-forming minerals. The mineral baddeley- ite, found in Ceylon and Brazil, is the oxide, Zr0 2 . Eudialyte, cata- pleiite, and the zircon-pyroxenes are complex silicates containing zirconia. Zircon syenite and eudialyte syenite are rare but well- known rocks, and zircon also occurs, though not commonly, in con- tact limestones. The most remarkable American locality for zircon is near Green River, in Henderson County, North Carolina, where it is found abundantly in a decomposed pegmatite dike. From this source many tons of zircon have been obtained. The typical thorium mineral is also a silicate, thorite, ThSi0 4 . The ideal species, however, has not been found, for the actual speci- mens are always more or less altered. The chief source of thoria, which is used in the manufacture of mantles for incandescent gas- burners, is from monazite sand, in which the thorium compounds exist as variable impurities. Thorianite, a thorium-uranium oxide from Ceylon, is noteworthy for being richer in helium than any other known mineral. Like uranium, thorium is strongly radio- active, and so are its compounds. 3 In the group of elements known as the metals of the rare earths, the following members have been identified: Scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, euro- pium, gadolinium, terbium, dysprosium, erbium, thulium, holmium, lutecium, and ytterbium. Among these yttrium and cerium may be regarded as the type elements, and they are, moreover, the most important. In the mineral kingdom these substances occur in a large number of compounds — fluorides, carbonates, silicates, phos- phates, columbates, and tantalates, minerals which are found, like the other species mentioned in this section, principally in granites, gneisses, and pegmatites. Cerium, which is always accompanied by lanthanum, neodymium, and praseodymium, is obtainable principally from three minerals which are found in reasonably large quantities. Cerite, a hydrous silicate of these elements, forms a bed in gneiss at Bastnas, Sweden. 1 Native tantalum has been reported from two localities in Siberia by P. Walther, Nature, 1909, p. 335, and W. von John, idem, 1910, p. 398. 2 See Werner von Bolton, Zeitschr. angew. Chemie, 1906, p. 1537. 3 For an elaborate paper on the occurrence of thorium in the mineral kingdom, see J. Schilling, Zeitschr. angew. Chemie, 1902, p. 869. 712 THE DATA OF GEOCHEMISTRY. It was for a long time the only commercial source of cerium com- pounds. Allanite, a more complex silicate of cerium, aluminum, and other bases, is also abundant enough to be an available ore. It is not a very rare mineral, and a notable locality for it is on Little Friar Mountain, Amherst County, Virginia. 1 Allanite has also been found associated with iron ores, as, for example, with the magnetite of Moriah, near Lake Champlain. Monazite, the phosphate of cerium, which is normally CeP0 4 , is, however, the chief source of the cerium earths at the present day. It is obtained for commercial purposes from detrital deposits of monazite sand, 2 and yields both cerium and thorium compounds. Monazite, the allied yttrium phosphate, xenotime, and allanite have all been adequately considered in the chapter upon rock-forming minerals. The following analyses of monazite are by S. L. Penfield: 3 Analyses of monazite. A. From Portland, Connecticut. B. From the sands ofBrindletown, North Carolina. C. From Amelia Court House, Virginia. A, B C p„(X 28. 18 29. 28 26. 12 Ce 2 0 3 38. 54 31. 38 29. 89 (La Di)oOo 28. 33 30. 88 26. 66 Th0 2 8. 25 6. 49 14. 23 Si0 2 1. 67 1. 40 2. 85 Ignition .37 .20 .67 100. 34 99. 63 100. 42 Yttria and its companions, erbia, terbia, ytterbia, etc., are obtained for the most part from gadolinite, Gl 2 FeYt 2 Si 2 O 10 . These oxides, therefore, are sometimes called the “gadolinite earths.” The type locality for this species is Ytterby, in Sweden, and other Swedish localities have yielded the mineral. A more remarkable occurrence of gadolinite and other allied minerals is at Baringer Hill, Llano County, Texas. Here, in a giant pegmatite containing enormous crystals of quartz and feldspar, gadolinite is found in large crystals, together with yttrialite, thorogummite, nivenite, fergusonite, allanite, tengerite, cyrtolite, rowlandite, mackintoshite, and yttrocrasite. Several of these species and varieties are peculiar to this locality. 4 1 See J. W. Mallet, Am. Jour. Sci., 3d ser., vol. 14, 1877, p. 397. 2 On the monazite sand of North Carolina, see H. B. C. Nitze, Bull. North Carolina Geol. Survey No. 9, 1898. Also the references on p. 356, ante. Nitze cites 37 analyses of monazite. On monazite sand in the tin-bearing alluvium of the Malay Peninsula, see Bull. Imp. Inst., vol. 4, 1906, p. 301. 3 Am. Jour. Sci., 3d ser., vol. 24, 1882, p. 250. The symbol Di represents the old didymium, which is now known to be a mixture of neodymium, praseodymium, samarium, etc. 4 See W. E. Hidden and J. B. Mackintosh, Am. Jour. Sci., 3d ser., vol. 38, 1889, p. 474; Hidden, idem, vol. 42, 1891, p. 430; Hidden and W. F. Hillebrand, idem, vol. 46, 1893, pp. 98, 208; Ilillebrand, idem, 4th ser., vol. 13, 1902, p. 145; Hidden, idem, vol. 19, 1905, p. 425; Hidden and C. H. Warren, idem, vol. 22, 1906, p. 515. CHAPTER XVI. THE NATURAL HYDROCARBONS. COMPOSITION. Natural gas, petroleum, bitumen, and asphaltum are all essentially compounds of carbon and hydrogen, or, more precisely, mixtures of such compounds in bewildering variety. They contain, moreover, many impurities — sulphur compounds, oxidized and nitrogenous sub- stances, etc. — whose exact nature is not always clearly defined. The proximate analysis of a petroleum or bitumen consists in separat- ing its components from one another, and in their identification as compounds of definite constitution. All the hydrocarbons fall primarily into a number of regular series, to each of which a generalized formula may be assigned, in accordance with the following scheme: 1. C n H 2n+2 . 2. C n H 2n . 3. C n H 2n _ 2 . 4. C n H 2n _ 4 . 5. C n H 2D _ 6 . 6. C n H 2n _ 8 . 7. C n H 2n _ 10 . 8. C n H 2n _ 12 . 18. C n H 2n _ 32 . Members of the first eight series have been discovered in petroleum. These expressions, however, have only a preliminary value, although they are often used in the classification of petroleums. Each one represents a group of series — homologous, isomeric, or polymeric, as the case may be — and for precise work these must be taken sepa- rately. The first formula, for example, represents what are known as the paraffin hydrocarbons, which begin with marsh gas or methane, CH 4 , and range at least as high as the compound C 35 H 72 . Even these are again subdivided into a number of isomeric series — the primary, secondary, and tertiary paraffins — which, with equal percentage com- position, differ in physical properties by virtue of differences of atomic arrangement within the molecules. Each member of the series differs from tho preceding member by the addition of the group CH 2 , and also by the physical characteristics of greater con- densation. Methane, CH 4 , for example, is gaseous; the middle mem- bers of the series are liquids, with regularly increasing boiling points ; the higher members are solids, like ordinary paraffin. These hydro- carbons are especially characteristic of the Pennsylvania petroleums, from which the following members of the series have been separated . 1 i The table is condensed from H. Hofer’s valuable work, Das Erdol, 2d ed., Braunschweig, 1906, pp. 58-59. A third edition appeared in 1912. 713 714 THE DATA OF GEOCHEMISTRY, Paraffins from Pennsylvania petroleum. Name. Formula. Melting point. Boiling point. 1 . Gaseous: °C. °C. Methane ch 4 —186 —164 Ethane c 2 h 6 —172. 1 — 84.1 Propane CoHo — 37 Butane C,H 10 + 1 2 . Liquid: Pentane CvH 19 37 Hexane ^5 12 " - - - - c«h 14 69 Heptane c 7 h 16 98 Octane CoH-io ..... 125 Nonane c 9 h 20 — 51 150 Decane CiqH- 22 - - - - - — 31 173 Endecane c„h 94 — 26 195 Dodecane ----- ^12^26 — 12 214 Tridecane C 13 U 28 ----- Tetradecane OiJT, n + 4 252 Pentadecane C lv Ho 9 Hexadecane C 1 f! Ho 4 18 3. Solid: Octodecane C 18 Hoo Eicosane v 18 3o ----- ^20^42 ----- 37 Tricosane ^23^48 ----- 48 Tetracosane c 9 ,h w 50-51 Pentacosane C 9 JL 9 53-54 Hexacosane CrJEL. 55-56 Octocosane ''20 54 60 Nonocosane 28 58 62-63 Hentriacontane P 29 tt 60 \ Jet 1 1 I r» 1 _ 66 Dotriacontane p TT 67-68 Tetratriacontane P 32 tt 66 71-72 Pentatriacontane a P 34 tt 70 \ Jet r 1 I nn _ _ 76 v 35 72 a For a description of these higher, solid paraffins, see C. F. Mabery , Am. Chem. Jour., vol. 33, 1905, p. 251. The literature of these substances is so voluminous that I can not attempt to give exhaustive references. C. Hell and C. Hagele (Ber. Deutsch. chem. Gesell., vol. 22, 1889, p. 504) have described an artificial hydro- carbon, C 60 H 122 . To this list the isomeric secondary paraffins isobutane, isopentane, isohexane, isoheptane, and isooctane must be added, and even then the list is probably not complete. For instance, the solid paraffins C 27 H 56 and C 30 H 62 have been found in petroleum. Natural gas consists almost entirely of paraffins, mainly of methane, with quite subordinate impurities. In six samples from West Vir- ginia, analyzed by C. D. Howard, 1 the total paraffins varied between 94.13 and 95.73 per cent. Methane ran from 79.95 to 86.48 per cent and ethane from 7.65 to 15.09. The following analyses from other sources may be cited more in detail: 2 1 West Virginia Geol. Survey, vol. 1 A, 1904, p. 556. 2 See also Mabery, Am. Chem. Jour., vol. 18, 1896, p. 215, for analyses of gas, largely methane, from south- ern Ohio. Hofer (Das Erdol, pp. 100-103) gives many other data. In Boverton Redwood’s Petroleum and its products, 2d ed., vol. 1, 1906, pp. 24&-250, full tables of analyses are given, with excellent references to literature. An unusual analysis is cited by G. B. Richardson in Bull. U. S. Geol. Survey No. 260, 1905, p. 481. Many other analyses are published in Trans. Am. Inst. Min. Eng., vol. 15, pp. 529 et seq. Many analyses of Kansas gases are given by H. P. Cady and D. F. McFarland, Kansas Univ. Geol. Survey, vol. 9, 1908, p. 228. They found in nearly all samples appreciable quantities of helium, and also argon and neon. See also Trans. Kansas Acad. Sci., vol. 20, 1907, p. 80; vol. 21, 1908, p. 64. See also E. Czakd, Zeitschr. anorg. Chemie, vol. 82, 1913, p. 249. For analyses of Californian gas see G. A. Burrell, Bull. U. S. Bur. Mines No. 19, 1911, p. 47. On liquefaction of natural gas, see L. C. Allen and G. A. Burrell, Tech. Paper U. S. Bur. Mines No. 10, 1912. THE NATURAL HYDROCARBONS. 715 Analyses of natural gas. A. From Creighton, Pennsylvania. B. From Pittsburgh, Pennsylvania. C. From Baden, Pennsylvania. D. From Vancouver, British Columbia. Analyses A to D by F. C. Phillips, Am. Chem. Jour., vol. 16, 1894, p. 406. Selected from a table of seventeen analyses to show extreme variations. E. Mean of four gases from Indiana and three from Ohio, analyzed by C. C. Howard for the United States Geological Survey. Cited by W J McGee, Eleventh Ann. Rept. U. S. Geol. Survey, pt. 1, 1891, p. 592. F. From Osawatamie, Kansas. From a table of seven analyses by E. H. S. Bailey, Kansas Univ. Quart., vol. 4, 1895, p. 1. > A B c D E F ch 4 93. 36 97. 63 Paraffins a 96. 36 98. 90 87. 27 93. 56 C 2 H 4 , etc .28 .22 CO .53 1. 32 co 2 3. 64 .40 .41 .14 .25 .22 h 2 None. None. None. None. 1. 76 None. n 2 None. .70 12. 32 6. 30 3. 28 .60 h 2 s None. None. None. None. .18 None. None. None. None. .29 Trace. 100. 00 100. 00 100. 00 100. 00 99. 93 100. 00 a Largely CH*, with more or less ethane. CO not found by Phillips. The analyses of Pennsylvania gases by S. P. Sadtler 1 gave some- what different results. In gas from four different wells he found, in percentages, CH 4 , 60.27 to 89.65; C 2 H 6 , 4.39 to 18.39; and H 2 , 4.79 to 22.50. These high figures for hydrogen are unusual and suggest a resemblance to coal gas. In all cases, however, methane is the pre- ponderating constituent, the characteristic hydrocarbon of natural gas. In the natural gas of Point Abino, Canada, F. C. Phillips 2 found 96.57 per cent of paraffins and 0.74 of H 2 S. Hydrocarbons of the form C n H 2n are, as constituents of petroleum, of equal importance to the paraffins. These again fall into several independent series, which vary in physical properties and in their chemical relations, but are identical in percentage composition. One series, the olefines, is parallel to the paraffin series, and the following members of it are said to have been isolated from petroleum. 3 1 Second Geol. Survey Pennsylvania, Rept. 1, 1876, pp. 146-160. Sadtler cites some analyses by other chemists. 2 Jour. Am. Chem. Soc., vol. 20, 1898, p. 696. 3 See H. Hofer, Das Erdol, p. 65. 716 THE DATA OF GEOCHEMISTRY. So-called “ olefines ” isolated from petroleum. Name. Formula. Melting point. Boiling point. 1 . Gaseous: Ethyl fin ft CJL -103 Propyl fin fi CJL - 18 Pntylfinfi CJL - 5 2. Liquid: Amylene C 5 H 10 + 35 68 Hexylene CJL 9 Heptylene C 7 H 14 98 Octylene C 8 H 1r 124 Nonylene C q H 18 153 Decylene CioH 2 o - - - - * 172 Undecylene Ci i H 99 195 Duodecylene GJL, 216 Tridecy lene O13H26- - - - - 232.7 Cetene Ci 6 H 32 - - - - - 275 ^20^-40 ----- 3. Solid: Cerotene C 97 H KA 65-66 Melene 27 54 * ^30^60 ----- 62 This table is probably exact in an empirical sense, but not so con- stitutionally. Hydrocarbons of the indicated composition have un- doubtedly been found, and some of them are certainly olefines. According to C. F. Mabery , 1 however, the true olefines, the “ open- chain” series, are present in petroleum at most in very small amounts. In Canadian petroleum Mabery and W. O. Quayle 2 identified hexyl- ene, heptylene, octylene, and nonylene. In other cases, and notably in the Russian petroleums, the compounds C n H 2n are not olefines, but cyclic hydrocarbons of the polymethylene series, which were origi- nally called naphtenes. They were at first supposed to be derivatives of the benzene series, and it is only within recent years that their true constitution has been determined. In Russian oils they are the prin- cipal constituents, and according to C. F. Mabery and E. J. Hudson 3 they also predominate in California petroleum. Members of the series from C 7 H 14 to C 15 H 30 were isolated from the California material. Mabery and S. Takano 4 also found that Japa- nese petroleum consisted largely of C n H 2n hydrocarbons. Other sim- ilar occurrences are recorded in the treatises of Hofer and Redwood . 5 6 The series C n H 2Q _ 2 is often called the acetylene series, after its first member, acetylene, C 2 H 2 . The lower members of this series 1 Jour. Am. Chem. Soc., vol. 28, 1906, p. 415. An important summary of our knowledge relative to the composition of American petroleums. 3 Proc. Am. Acad. Arts and Sci., vol. 41, 1905, p. 89. a Idem, vol. 36, 1901, p. 255. « Idem, p. 295. 6 In vol. 2 of Redwood’s great work, there is a bibliography of petroleum covering nearly 6,000 titles. In the text Redwood gives a full discussion of the composition of various petroleums, and so too does Hofer. Only the barest outline of the subject can be given here, and that must presuppose a knowledge on the part of the reader of elementary organic chemistry. THE NATURAL HYDROCARBONS. 717 seem not to have been found in petroleum; but several of its higher members are characteristic of oils from Texas, Louisiana, and Ohio. In oil from the Trenton limestone of Ohio, Mabery and O. H. Palm 1 found hydrocarbons having the composition C 19 H 36 , C 21 H 40 , C 22 H 42 , and C 24 H 46 . With these compounds were members of the C n H 2n series as high as C 17 H 34 . There were also members of the next series, C n H 2 n _ 4 — namely, C 23 H 42 , C 24 H 44 , and C 25 H 46 . In petroleum from Louisiana, C. E. Coates and A. Best 2 found the hydrocarbons C 12 H 22 and C 14 H 26 . These, together with C 16 H 30 , were also separated by Mabery 3 from Texas oils. These oils are furthermore peculiar in containing free sulphur, which separates out in crystalline form . 4 In petroleum from Santa Barbara, California, Mabery 5 discovered hydrocarbons of the three series C n H 2n _ 2 , C n H 2n _ 4 , and C n H 2n _ 8 , rep- resented by the formulae C 13 H 24 , C 16 H 30 , C 17 H 30 , C 18 H 32 , C 24 H 44 , C 27 H 46 , and C 29 H 50 . A remarkable oil from the Mahoning Valley, Ohio, according to Mabery , 6 consists almost entirely of hydrocarbons of the series C n H 2U _ 2 and C n H 2n _ 4 . Paraffins are entirely absent. Hydrocarbons of the series C n H 2n - 6 , the “ aromatic” or benzene series, occur in nearly all petroleums, but in usually subordinate amounts. Their empirical formulae, ignoring the existence of iso- meric compounds, are as follows : Benzene Toluene. Xylene. . Cumene. Cymene. Etc. c 6 h 6 c 7 h 8 c 8 h 10 c 9 h 12 According to Mabery , 7 Pennsylvania petroleum contains small pro- portions of the lower members of this series, and Mabery and Hudson 8 found larger amounts of them, especially of the xylenes, in California oil. Numerous other examples are cited by Hofer and Redwood, but they need not be multiplied here . 9 Naphthalene, C 10 H 8 , is the only compound of the series C n H 2n _ 12 which has been certainly identified 1 Am. Chem. Jour., vol. 33, 1905, p. 251. 2 Jour. Am. Chem. Soc., vol. 25, 1903, p. 1153. 3 Idem, vol. 23, 1901, p. 264. See also on Texas oils, C. Richardson and E. C. Wallace, Jour. Soc. Chem. Ind., vol. 20, 1901, p. 690; F. C. Thiele, Am. Chem. Jour., vol. 22, 1899, p. 489; W. B. Phillips, Bull. Univ. Texas No. 5, 1902; C. W. Hayes and W. Kennedy, Bull. U. S. Geol. Survey No. 212, 1903; R. T. Hill, Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 363; and N. M. Fexmeman, Bull. U. S. Geol. Survey No. 282, 1906. Fenneman describes both Texas and Louisiana petroleums. On the composition of Kansas oils, see F. W. Bushong, Kansas Univ. Geol. Survey, vol. 9, 1908, p. 303. In the same volume, p. 187, E. Haworth discusses the origin of oil and gas. * See C. Richardson and E. C. Wallace, Jour. Soc. Chem. Ind., vol. 21, 1902, p. 316; and Thiele, Chem. Zeitung, vol. 26, 1902, p. 896. 5 Am. Chem. Jour., vol. 33, 1905, p. 270. 6 Jour. Ind. Eng. Chem., vol. 6, 1914, p. 101. 7 Jour. Am. Chem. Soc., vol. 28, 1906, p. 418. 3 Proc. Am. Acad. Arts and Sci., vol. 36, 1890, p. 255. 9 R. Zaloziecki and J. Hausmann (Zeitschr. angew. Chemie, 1907, p. 1761) have called attention to the richness of Roumanian petroleum in aromatic hydrocarbons. 718 THE DATA OF GEOCHEMISTRY. in petroleum. It was found by C. M. Warren and F. H. Storer 1 in Rangoon oil, and also by Mabery and Hudson in oil from California. In one of Mabery and Hudson’s distillations of crude oil so much naphthalene was present that the distillate became solid on slight cooling. Still more complex hydrocarbons have been found in petro- leum residues, but it is possible that they were formed during the process of refining. It is not certain that they were present in the natural oil. 2 In many petroleums small quantities of oxidized bodies are con- tained, sometimes complex acids, sometimes phenols. According to Mabery, 3 the phenols are found in notable proportions in some Cali- fornia oils but not in petroleum from the eastern part of the United States. Nearly all petroleums contain nitrogen, from a trace up to 1 per cent and over. It appears to exist in most cases, if not in all, in the form of complex organic bases, but their constitution is yet to be determined. They are peculiarly abundant in California oil, in which they were discovered by S. F. Peckham, 4 and Mabery 5 * has shown that in some cases they constitute from 10 to 20 per cent of the crude petroleum. Mabery isolated compounds of this class ranging from Cj 2 H 17 N to C 17 H 21 N, although these formulae are subject to some uncertainty. Petroleum free from sulphur is extremely rare, but the amount of this constituent is commonly very small. In some instances, how- ever, the sulphur compounds are annoyingly abundant, as, for exam- ple, in the Lima oil of Ohio. In this oil Mabery and A. W. Smith 0 found normal sulphides of the paraffin series, and isolated ten com- pounds ranging from methyl sulphide, C 2 H 6 S, to hexyl sulphide, C 12 H 26 S. In Canadian petroleum Mabery and Quayle 7 discovered another series of sulphur compounds, of the general formula C n H 2n S, which they named thiophanes. Eight members of this series were described, between C 7 H 14 S and C 18 H 36 S. Other sulphur compounds have been mentioned as occasional admixtures in petroleum, and the occurrence of free sulphur in Texas oil has already been noted. 8 » Mem. Am. Acad. Arts and Sci., 2d ser., vol. 9, 1865, p. 208. 2 For data and references, see Hofer, Das Erdol, p. 74. 2 Jour. Am. Chem. Soc., vol. 28, 1906, p. 596. * Am. Join. Sci., 3d ser., vol. 48, 1894, p. 250. s Jour. Soc. Chem. Ind., vol. 19, 1900, p. 505. F. X. Bandrowsky (Monatsh. Chemie, vol. 8, 1887, p. 224) and A. Weller (Ber. Deutsch. chem. Gesell., vol. 20, 1887, p. 2097) have detected nitrogenous bases in Euro- pean oils. s Am. Chem. Jour., vol. 13, 1891, p. 233. 7 Proc. Am. Acad. Arts and Sci., vol. 41, 1905, p. 89. A paper by R. Kayser, published in 1897, con- tains data relative to sulphur compounds in Syrian asphalt oils. I have not been able to consult his original memoir. Cited by W. C. Day in Jour. Franklin Inst., vol. 140, 1895, p. 221, and also in Kohler’s treatise on asphalt. 8 On sulphur in California petroleum, see S. F. Peckham, Proc. Am. Philos. Soc., vol. 36, 1897, p. 108. Also S. F. and H. E. Peckham, Jour. Soc. Chem. Ind., vol. 16, 1897, p. 996, on the sulphur content of bitumens. THE NATURAL HYDROCARBONS. 719 Between liquid petroleum and solid asphalt there are numberless intermediate substances. Indeed, there is no distinct break in the continuity of the series from natural gas to bituminous coal . 1 The latter contains solid hydrocarbons of undetermined character, which break up under the influence of heat, yielding coal gas and various tarry products. Some of the heavier hydrocarbon mixtures are vis- cous, pasty semifluids; others are black, brittle solids, which resem- ble coal in their outward appearance. Albertite, grahamite, uintaite, and the so-called “ pitch coal” of Oregon are familiar examples of these solid forms. Many of the solid hydrocarbons have been described as mineral species and given specific names . 2 Scheererite, fichtelite, konlite, hatchettite, ozokerite, zietrisikite, elaterite, hartite, napalite, tab- byite, etc., are among the substances. They vary widely in compo- sition, being commonly, if not in all cases, mixtures, and they repre- sent different series of hydrocarbons. They also occur under widely differing conditions, indicating genetic distinctions. Some are found in coal in such a way as to show their derivation from vegetable resins; others appear to be inspissated petroleums; others again are associated with metallic ores, and are seemingly of solfataric origin. Napalite, for example, is found with ores of mercury in California, and the oxygenated compound idrialite occurs under similar condi- tions in the quicksilver mine of Idria . 3 Most of these substances are found in small quantities, and are so imperfectly described that they need no detailed consideration here. Others, like ozokerite, alber- tite, grahamite, uintaite, and the various asphaltums and bitumens, occur in large deposits and are of commercial significance. Ozokerite, for instance, is an important source of paraffin. In fact, it appears to consist largely of the higher hydrocarbons of the paraffin series, although some varieties probably contain compounds of the form C n H 2n . In Caucasian ozokerite F. Beilstein and E. Wiegand 4 found a hydrocarbon to which they gave the name lekene, and which appears to be a polymer of CH 2 . In the ozokerite of Utah 5 6 paraffin predominates, of composition between C 18 H 38 and C 25 H 52 . 1 This continuity, and the probable community of origin is emphasized by Mabery, Jour. Ind. Eng. Chem., vol. 6, 1914, p. 101. 2 See Dana, System of mineralogy, 6th ed., pp. 996-1024. s Bitumen is also common in the New Almaden mines. Its association with the lead and zinc ores of Missouri and with the copper-bearing shales of Mansfeld, Germany, is an occurrence of a different order, with which solfataric action has nothing to do. * Ber. Deutsch. chem. Gesell., vol. 16, 1883, p. 1547. 6 On Utah ozokerite, see J. S. Newberry, Am. Jour. Sci., 3d ser., vol. 17, 1879, p. 340; and A. N. Seal, Jour. Franklin Inst., vol. 130, 1890, p. 402. A monographic paper on ozokerite by E. B. Gosling (School of Mines Quart., vol. 16, 1894, p. 41) contains a bibliography of the mineral. Der Erdwachsbergbau in Boryslaw, by J. Muck, Berlin, 1903, is an important monograph on ozokerite. 720 THE DATA OF GEOCHEMISTRY. Uintaite, or gilsonite, 1 is another black, brittle, lustrous mixture of hydrocarbons found in the Uinta Mountains, Utah. Another similar mineral from Utah was named wurtzilite by W. P. Blake. 2 The exact nature of these hydrocarbons is yet to be determined. The same remark may be applied to the albertite 3 of New Brunswick, the grahamite 4 of West Virginia, the “ pitch coal” 5 of Coos Bay, Oregon, and other like substances. The albertite and grahamite fill veinlike fissures in the country rock, into which they were pos- sibly injected when fluid. These hydrocarbons, it should be observed, are fusible, therein differing from coal. They are also variably soluble in organic solvents. Their origin is obscure. Some authors attribute them to the oxidation of lighter oils; others, like S. F. Peckham 6 regard them as residues from a natural distillation of petroleum. The oxidation theory is borne out by the fact that grahamite, according to White, contains 13.5 to 14.7 per cent of oxygen, while W. C. Day found 14.61 per cent in the Oregon mineral. Furthermore, W. P, Jenney, 7 by aspirating heated air through Penn- sylvania petroleum for several hours, partially converted the oil into a substance resembling grahamite. In this experiment, obvi- ously, the more volatile hydrocarbons were distilled away. The two processes, oxidation and distillation, went on simultaneously 0 In most cases the solid hydrocarbons found in nature are not given specific names, but are known generically as asphalt or bitumen. The pasty, viscid varieties are called maltha. There are also mix- tures of these substances with the material of sandstones, shales, and limestones, forming the so-called asphalt rocks, from which oils or tars can be separated by distillation or melting. Asphalt and asphalt rock are widely diffused in nature, being found in all parts of the world. Probably the most remarkable occurrence of asphalt is that of the famous “ Pitch Lake” in Trini- dad, which has been many times described — best, so far as chemical lUintaite has priority, but gilsonite is the name most commonly used. On this bitumen see J. M. Locke, Trans. Am. Inst. Min. Eng., vol. 17, 1887, p. 162; R. W. Raymond, idem, vol. 18, 1888, p. 113; W. P. Blake, idem, vol. 18, 1890, p. 563; G. H. Stone, on Utah and Colorado asphalts, Am. Jour. Sci.,3d ser., vol. 42, 1891, p. 148; and G. H. Eldridge, Seventeenth Arm. Rept. U. S. Geol. Survey, pt. 1, 1896, p. 915, and also Bull. No. 213, 1903, p. 296. A chemical investigation of gilsonite by W. C. Day is reported in Join*. Franklin Inst., vol. 140, 1895, p. 221. 2 Trans. Am. Inst. Min. Eng., vol. 18, 1890, p. 497; Eng. and Min. Jour., vol. 48, 1889, p. 542; vol. 49, 1890, p. 106. s C. H. Hitchcock, Am. Jour. Sci., 2d ser., vol. 39, 1865, p. 267; and S. F. Peckham, idem, vol. 48, 1869, p. 362. 4 J. P. Lesley, Proc. Am. Philos. Soc., vol. 9, 1863, p. 183; and I. C. White, Bull. Geol. Soc. America, vol. 10, 1898, p. 277. J. P. Kimball (Am. Jour. Sci., 3d ser., vol. 12, 1876, p. 277) has described a ‘'grahamite” from Mexico. See also B. Doss, Centralbl. Min., Geol. u. Pal., 1914, p. 609. & W. C. Day, Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 3, 1898, p. 370. 6 Peckham, loc. cit., and also Am. Jour. Sci., 3d ser., vol. 48, 1894, p. 389. 7 Am. Chemist, vol. 5, 1875, p. 359. For analyses of Texas grahamite see E. T. Dumble, Trans. Am. Inst. Min. Eng., vol. 21, p. 601. THE NATURAL HYDROCARBONS. 721 questions are concerned, in three papers by Clifford Richardson. 1 Ac- cording to Richardson, the “lake” occupies the crater of an old mud volcano or geyser, which has become filled with “pitch.” This is an emulsion of water, gas, bitumen, with some other organic substances, and mineral matter. The gas, which is continually evolved, consists principally of hydrogen sulphide and carbon dioxide. The water which permeates the pitch is rich in saline matter, mainly sodium chloride, but it also contains small quantities of borates and of ammoniacal salts, which indicate that it is probably of volcanic ori- gin. An analysis of the purified bitumen gave the following results: Analysis of Trinidad bitumen. C 82.33 H 10.69 S 6.16 N 81 99. 99 The sulphur content of this material led to an investigation of other asphalts. In eighteen hard asphalts the sulphur ran from 3.28 to 9.76 per cent, while in soft asphalts or malthas only 0.60 to 2.29 per cent was found. This leads to the suggestion that sulphur has been active in hardening the bitumen; that is, in effecting the con- densation and polymerization # of the hydrocarbons. 2 Oxygen may act in the same way, but is eliminated, after union with hydrogen, as water. Richardson concludes that the bitumen consists in great part of unsaturated hydrocarbons, but their exact nature remains undetermined. 3 He also describes the Bermudez, Venezuela, locality. 1 Jour. Soc. Chem. Ind., vol. 17, 1898, p. 13; Rept. Inspector Asphalts and Cements, Washington, D. C., year ending June 30, 1892; Proc. Am. Soc. Testing Materials, vol. 6, 1906, p. 509. See also N. S. Manross, Am. Jour. Sci., 2d ser., vol. 20, 1855, p. 153. W. Merivale (Trans. North of England Inst. Mech. and Min. Eng. , vol. 47, 1898, p. 119, has described the “ manjak” of Barbadoes, an asphalt resembling that of Trinidad. See also R. W. Ells, Ottawa Naturalist, vol. 23, 1907, p. 73. A recent paper by Richardson is in Jour. Phys. Chem., vol. 19, 1915, p. 241. 2 A well-known method for preparing H 2 S is to fuse paraffin with sulphur. The reaction doubtless involves a union of the residues from which hydrogen has been partially withdrawn— that is, the forma- tion of a more condensed hydrocarbon molecule. The reaction does not seem to have been exhaustively studied. Some artificial “asphalts” have been prepared by heating petroleum residues with sulphur, and a similar substance, “byerlite,” is made by the slow distillation of such residues in presence of air. The latter product resembles gilsonite. See C. F. Mabery and J. H. Byerly, Am. Chem. Jour., vol. 18, 1896, p. 141. See also references to the sulphur processes in Kohler’s monograph, p. 119. s On the composition of asphalt, see also H. Endemann, Jour. Soc. Chem. Ind., vol. 16, 1897, p. 121. For analyses of Texas asphalts see H. W. Harper, Bull. Texas Univ. Min. Survey No. 3, 1902, p. 108. Elaborate data are also given by G. H. Eldridge, Twenty-second Ann. Rept. U. S. Geol. Survey, pt. 1, 1901, p. 209, in a long paper on the asphalts and bituminous rocks of the United States. Important monographs on asphalt are by H. Kohler, Die Chemie und Technologic der naturlichen und kiinstlichen Asphalte, Braun- schweig, 1904; and P. Narcy, Les bitumes, Paris, 1898. See also T. Posewitz, Mitt. K. ungar. geol. Anstalt, vol. 15, Heft 4, 1907, pp. 235-463, on petroleum and asphalt in Hungary. Memoirs on the proximate com- position of petroleum are innumerable. I have cited, principally, those of Mabery, because they relate specifically to American oils. The limited scope of this volume prevents me from going into details, and a vast literature must be passed over. The fundamental labors of Pelouze and Cahours in France, of Schor- lemmer in England, of Markownikoff in Russia, and of others in nearly every country of Europe, can not be given the consideration here which is properly due them. 97270°— Bull. 616—16 16 722 THE DATA OF GEOCHEMISTRY. In a recent article Richardson 1 has also studied at length the nature of grahamite, and given many analyses of samples from different localities. It is mainly derived from the condensation of paraffin oils, and so differs from gilsonite and manjak, which were formed by unsaturated hydrocarbons. Grahamite differs from albertite in being soluble in carbon bisulphide; a distinction which leads to the designation of albertite as a pyrobitumen, or more com- pletely metamorphosed petroleum. Richardson also gives examples of the presence of vanadium in the ash of grahamite, a fact already noticed in the preceding chapter. SYNTHESES OF PETROLEUM. Hydrocarbons, notably methane, ethane, acetylene, and benzene, have been repeatedly prepared by laboratory methods from inorganic sources, and also by the breaking down of more complex organic matter. Some of the methods employed have led to the production of substances resembling petroleum, and these alone demand con- sideration here. Let us begin with the inorganic material. When cast iron is dissolved in an acid, hydrogen is evolved, hut with contaminations that were long ago recognized as akin to hydro- carbons. In 1864 H. Hahn 2 attempted to determine their exact nature by passing the gas through bromine. Organic bromides were thus formed, corresponding to the olefines from C 2 H 4 to C 7 H 14 , the general formula being C n H 2n Br 2 . In hydrogen evolved from spiegel- eisen Hahn found still higher hydrocarbons, up to C 16 H 32 . These were collected by direct condensation in wash bottles without the use of bromine. In 1873 similar experiments were reported by F. H. Williams, 3 who dissolved spiegeleisen in hydrochloric acid. The gas evolved was passed through tubes immersed in a freezing mixture, and afterward through bromine. In one experiment 7,430 grams of iron gave 49 grams of directly condensible hydrocarbons, with 325.5 grams of bromides; and other experiments yielded similar results. The nature of the hydrocarbons was not further investigated. Much more elaborate researches were those conducted by S. Cloez, 4 in the years 1874 to 1878. Hydrochloric or sulphuric acid was allowed to act on large quantities of spiegeleisen, and the hydro- gen, partly by direct condensation and partly by absorption in bro- mine, yielded abundant hydrocarbons and their bromides, which were separated by fractional distillation and identified. Ferromanganese gave a particularly large product of hydrocarbons, and a cast man- ganese, containing 85.4 per cent of metal, was even attacked by water 1 Jour. Am. Chem. Soc., vol. 32, 1910, p. 1032. 2 Liebig’s Annalen, vol. 129, 1864, p. 57. Hahn gives references to the earlier investigations. 2 Am. Jour. Sci., 3d ser., vol. 6, 1873, p. 363. * Compt. Rend., vol. 78, 1874, p. 1565; vol. 85, 1877, p. 1003; vol. 86, 1878, p. 1248. THE NATURAL HYDROCARBONS. 723 alone, with evolution of similarly carburized hydrogen. In his first paper Cloez reports that he obtained octylene, C 8 H 16 , by direct con- densation, with bromheptylene, C 7 H 13 Br, and bromoctylene, C 8 II 15 Br, from the bromine solution. In his second paper he described the products obtained during the solution of 600 kilograms of white cast iron, which yielded 640 grams of oily hydrocarbons, 2,780 grams of bromolefines, and 532 grams of paraffins. Seven of the latter were identified, from C 10 H 22 up to C 16 H 34 , hydrocarbons identical with those which occur in petroleum; that is, from the carbides con- tained in cast iron, a mixture of hydrocarbons chemically resembling petroleum can be prepared. In recent years, through the development of the electric furnace by Moissan, many carbides have been made and investigated. The greater number of these compounds react with water, yielding hydro- carbons, and the production of acetylene, as an iUuminating gas, from calcium carbide, has become an important industry. The metallic carbides, however, differ in their yield of hydrocarbons, and the results obtained may be summarized as follows: 1 The carbides of lithium, sodium, potassium, calcium, strontium, and barium, treated with water, yield acetylene, C 2 H 2 . The carbides of aluminum and glucinum yield principally methane, CH 4 . The carbide of manganese yields a mixture of methane and hydrogen. The carbides of yttrium, lanthanum, cerium, thorium, and ura- nium yield mixtures of acetylene, methane, ethylene, and hydrogen. The cerium, lanthanum, and uranium compounds also yield some liquid and solid hydrocarbons. From 4 kilograms of uranium car- bide Moissan obtained 100 grams of liquid hydrocarbons, consisting largely of olefines, with some members of the acetylene series and some saturated compounds. According to R. Salvadori, 2 hydrocarbons can be generated by heating together calcium carbide and ammonium chloride, an observation which has been confirmed by A. Brun. 3 Furthermore G. Steiger, in the laboratory of the United States Geological Survey, obtained both saturated and unsaturated hydrocarbons by the simi- lar action of ammonium chloride upon the native iron of Ovifak. Ammonium chloride, it must be remembered, is one of the most char- acteristic of volcanic emanations. The bearing of these observations upon theories of petroleum formation will be discussed later. 1 See H. Moissan, Compt. Rend., vol. 122, 1896, p. 1462. Also a summary by J. A. Mathews, Jour. Am. Chem. Soc., vol. 21, 1899, p. 647. Berthelot (Compt. Rend., vol. 132, 1901, p. 281) has discussed the reac- tions thermochemically. 2 Gazz. chim. ital., vol. 32, 1902, p. 496. 3 Arch, sci. phys. nat., 4th ser., vol. 27, 1909, p. 113. 724 THE DATA OF GEOCHEMISTRY. It will be observed that acetylene is a common product of these reactions. But acetylene is not a constituent of petroleum. P. Sabatier and J. B. Senderens, 1 however, have found that when a mix- ture of hydrogen and acetylene is brought into contact with finely divided metallic nickel at a temperature of 200° a mixture of paraffins is formed which resembles Pennsylvania petroleum. Acetylene alone, in presence of nickel, also yields aromatic hydrocarbons, and a mix- ture is produced resembling Russian oil. In this connection it should be noted that M. Berthelot 2 long ago proved that acetylene, when heated to the temperature at which glass begins to soften, poly- merizes into benzene. Three molecules of C 2 H 2 yield one of C 6 H 6 . Benzene itself, when heated under suitable conditions, loses hydrogen, and the residues combine to form diphenyl, C 12 H 10 : 2C 6 H 6 -2H = C 12 H 10 + H 2 From acetylene, then, as a starting point, higher hydrocarbons may be generated. These, again, at high temperatures, act upon one another, and the complexity of the final product may be very great. Furthermore, carbon and hydrogen can unite directly. When the electric arc is formed between carbon terminals in an atmosphere of hydrogen, acetylene is produced — a reaction discovered by Berthelot. 3 According to W. A. Bone and D. S. Jerdan, 4 methane and ethane are formed at the same time, but at a lower temperature (about 1,200°) methane is the sole product of the union. Even by passing hydro- gen over charcoal at 1,200° methane may be formed. So much for the inorganic syntheses of hydrocarbons. On the other side of the question it has long been known that the destructive distillation of organic matter, animal or vegetable, under conditions which preclude the free access of air, will produce hydrocarbons and nitrogenous bases. This fact was first applied to the production of an artificial petroleum by C. M. Warren and F. H. Storer 5 as far back as 1865. They prepared a lime soap from menhaden (fish) oil, which, on destructive distillation, yielded a mixture of hydrocarbons hardly distinguishable from coal oil 6 or kerosene. From this mix- ture they isolated and identified the paraffins pentane, hexane, hep- tane, and octane; the olefines amylene, hexylene, heptylene, octylene, 1 Compt. Rend., vol. 134, 1903, p. 1185. Similar results to those of Sabatier and Senderens have also been obtained by K. Charitschkoff, Chem. Zentralbl., 1907, p. 294. A paper by Charitschkoff on the origin of petroleum is abstracted in Jour. Chem. Soc., vol. 102, pt. 1, 1912, p. 329. 2 Annales chim. phys., 4th ser., vol. 12, 1867, p.*52. According to E. Briner and A. Wroczynski (Arch. Sci. Phys. Nat., 4th ser., vol. 32, 1911, p. 389), the polymerization of acetylene is much aided by pressure. 3 Annales chim. phys., 3d ser., vol. 67, 1863, p. 64. 4 Jour. Chem. Soc., vol. 71, 1897, p. 41; vol. 79, 1901, p. 1042. See also J. N. Pring and R. S. Hutton, idem, vol. 89, 1906, p. 1591. Also W. A. Bone and H. F. Coward, Jour. Chem. Soc., vol. 93, 1908, p. 1975; vol. 97, 1910, p. 1219. 6 Mem. Am. Acad. Arts and Sci., 2d ser., vol. 9, 1865, p. 177. 6 Coal oil is oil distilled from shale or coal. The term is not synonymous with petroleum, although it is often, loosely, so used. THE NATURAL HYDROCARBONS. 725 nonylene, decylene, undecylene, and duodecylene ; together with ben- zene, toluene, xylene, and isocumene, members of the aromatic series. A true artificial petroleum had been prepared. In 1888 C. Engler’ s famous investigations 1 were announced. He distilled menhaden oil, unsaponified, at a temperature between 320° and 400°, and under a pressure of ten atmospheres. The distillate resembled petroleum, and contained the paraffins from C 5 H 12 up to C 7 II 16 . In a later memoir 2 he mentions the isolation of normal octane and nonane, with secondary hexane, heptane, and octane. In a still later research with T. Lehmann 3 he also obtained olefines from C 6 H 12 up to C 9 H 18 and some derivatives of the benzene series. These experiments upon fish oil confirmed those of Warren and Storer, but differed from theirs in the direct use of the oil instead of its fatty acids alone. The lime soap of the American chemists contained only the acids of the oil, separated from its glycerine; the entire oil was used by Engler. From his crude product Engler also prepared an illuminating oil, practically indistinguishable from commercial kerosene. 4 Analogous experiments, but with a somewhat different purpose, were carried out by W. C. Day. 5 A mixture of fish (fresh herring) and resinous pine wood was distilled from an iron retort, the process being continued to complete carbonization of the residual material. The distillate consisted of a mixture of oil and water, and the oil, upon redistillation, yielded a residue closely resembling gilsonite. When fish alone was distilled, the final product was more like elater- ite. Wood alone gave a similar oil, with a similar residue on redis- tillation. In this research, then, artificial asphalts were obtained, curiously resembling the natural substances. They also, like ordi- nary asphalt, contained some nitrogen. Vegetable oils likewise yield hydrocarbons upon destructive dis- tillation. S. P. Sadtler, 6 for example, established this fact with regard to linseed oil, but the nature of the product was not completely determined. Engler 7 obtained hydrocarbons by the distillation of colza and olive oils, as well as from fish oil, butter, and beeswax. Furthermore, J. Marcusson 8 cites an experiment in which pure oleic acid was heated for several hours to 330° in a sealed tube. On open- ing the tube there was a strong evolution of gas, and in the residue a 1 Ber. Deutsch. chem. Gesell., vol. 21, 1888, p. 1816. a Idem, vol. 22, 1889, p. 592. 3 Idem, vol. 30, 1897, p. 2365. A paper by C. Engler and E. Severin on artificial petroleum is in Zeitschr. angew. Chemie, vol. 25, 1912, p. 153. 4 Observations confirmed by Redwood, Petroleum and its products, 2d ed., vol. 1, p. 259. 6 Am. Chem. Jour., vol. 21, 1899, p. 478. « Proc. Am. Philos. Soc., vol. 36, 1897, p. 93. 7 Cong, intomat. du pgtrole, Paris, 1900, p. 20. s Chem. Zeitung, vol. 30, 1906, p. 789. 726 THE DATA OF GEOCHEMISTRY. product was found which, completely resembled a lubricating oil from petroleum. These examples are only two out of many which might be adduced. ORIGIN OF PETROLEUM. Probably no subject in geochemistry has been more discussed than that of the origin of petroleum. Theory after theory has been pro- posed, and controversy is still active. The evidence is abundant, but contradictory, and leads to different conclusions when studied from different points of view. The theories so far advanced may be divided into two categories — the inorganic and the organic. Let us examine the hypotheses sepa- rately. The earlier speculations connecting the formation of petro- leum with volcanic phenomena may be passed over, for the reason that they were framed at a time when essential evidence was not available. They were speculations, nothing more. The modern era begins with a memoir by M. Berthelot, 1 published in 1866. Berthelot started from a supposition of Daubree that the interior of the earth might contain free alkaline metals. Upon these, as Ber- thelot had previously shown, carbon dioxide could react at high tem- peratures, forming acetylides from which, with water, acetylene would be generated, with all of its possibilities of condensation into higher hydrocarbons. The weak point of the hypothesis, which Ber- thelot only advances tentatively, is that no evidence exists to show that the alkaline metals are present in an uncombined state at any point below the surface of the earth. The starting point is a pure assumption, which is more likely to be erroneous than true. Leaving out of account the oft-cited paper by H. Byasson, 2 which has no present value, we come next to the famous carbide theory of D. Mendeleef, 3 published in 1877. This theory presupposes the existence of iron carbides within the earth, to which percolating waters gain access, generating hydrocarbons. If such carbides exist at rea- sonable depths below the surface of the earth, the suggested reactions would presumably take place; but the major premise is as yet unproved. The actual existence of the carbides in nature remains to be demonstrated. Mendeleef’ s hypothesis naturally attracted much attention and was rendered plausible by researches like those of Hahn, Williams, and Cloez upon the production of hydrocarbons from cast iron. It was still further strengthened by the discoveries of Moissan in his development of the electric furnace, and has had many advocates. 1 Annales chim. phys., 4th ser., vol. 9, 1866, p. 481. 8 Compt. Rend., vol. 73, 1871, p. 611. A later, separate brochure by Byasson I have not seen. 3 Ber. Deutsch. chem. Gesell., vol. 10, 1877, p. 229; Jour. Chem Soc., vol. 32, p. 283. See also Mendel&f’s Principles of chemistry, English translation, vol. 1, 1891, pp. 364-366. THE NATURAL HYDROCARBONS. 727 Moissan 1 himself has adopted it, and also suggested that volcanic explosions may perhaps be caused by the action of water upon subter- ranean carbides. He admits, however, that some petroleums are pos- sibly of organic origin. The presence of marsh gas in volcanic ema- nations 2 may be cited in support of Moissan’s suppositions, but this well-recognized fact can be interpreted otherwise. Another favorable datum has been furnished by O. Silvestri, 3 who found in basaltic lavas from near Etna both liquid oils and a solid paraffin which melted at 56°. Similar observations have been made by A. Brun, 4 in his study of the Javanese volcanoes. He regards the petroleum of Java as of volcanic origin. But these oils, as well as the marsh gas, may con- ceivably have been formed either through a direct union of carbon and hydrogen or from material distilled by volcanic heat out of adjacent sedimentary rocks. The same considerations also apply to the petroleum field near Tampico, Mexico, as described by E. Ordonez, 5 which is cited by E. Coste 6 in support of his elaborate argument in favor of the inorganic origin of petroleum. In this field the oil rises close to volcanic cones; which, however, have been forced up through a great thickness of Cretaceous shales. The possi- bility of a distillation of oil from organic matter in the sediments must here be taken into account. A different line of investigation relative to the genesis of petroleum is that proposed tentatively by G. F. Becker. 7 If petroleum is derived from iron carbides, as the inorganic theory assumes, there should be magnetic irregularities in oil-bearing regions. This he finds to be the case in the Appalachian oil field, where the lines of magnetic declination are sensibly deflected. Similar irregularities appear in the oil fields of California, and magnetic disturbances are also recorded in the region of the Caucasus. The observations are not absolutely conclusive, but they are compatible with the inorganic theory. Two other speculations upon the genesis of petroleum from inor- ganic matter remain to be mentioned, if only for the sake of com- pleteness. N. V. Sokoloff, 8 in 1890, argued that the bitumens are of cosmic origin, formed initially during the consolidation of the planet, inclosed within the primeval magma, and since emitted from the earth’s interior. In support of this conception he cites the occasional. 1 Compt. Rend., vol. 122, 1896, p. 1462. See also S. Meunier, idem, vol. 123, 1896, p. 1327. 2 See ante, Chapter VIII. 3 Gazz. chim. ital., vol. 7, 1877, p. 1; vol. 12, 1882, p. 9. * Arch. sci. phys. nat., 4th ser., vol. 27, 1909, p. 113. 5 Min. and Sci. Press, vol. 95, 1907, p. 249. 8 Jour. Canadian Min. Inst., vol. 12, 1909, p. 273. For earlier papers by Coste see the same journal, vol. 6, 1903, p. 73, and Trans. Am. Inst. Min. Eng., vol. 35,1905, p. 288. F. Rigaud (Rev. univ. des mines, 4th ser., vol. 31, 1910, p. 145) has also argued in favor of the inorganic origin of petroleum. t Bull. U. S. Geol. Survey No. 401, 1909. 8 Bull. Soc. imp. nat. Moscou, new ser., vol. 3, 1890, p. 720. 728 THE DATA OF GEOCHEMISTRY. finding of hydrocarbons in meteorites , 1 cases in which the possibility of an organic origin seems to be absolutely excluded. The other speculation is that of O. C. D. Ross , 2 who has tried to show that petroleum may originate from the action of solfataric gases upon limestones. Ross wrote various chemical equations to show how the reactions might occur, but they are improbable and experimentally unverified. It will be seen, upon consideration, that these inorganic theories concerning the origin of petroleum relate not only to its proximate genesis, but to fundamental questions of cosmology. SokolofFs hypothesis is an indication of this fact, and the assumption of carbides within the earth represents an effort in the same direction. An illus- tration of this implication is to be found in Lenicque’s remarkable memoir , 3 which was cited in Chapter II of this volume. If the molten globe had at any time a temperature like that of the electric furnace, carbides, silicides, nitrides, etc., would be among the earliest compounds to form, and oxidation could not begin until later. Under such conditions some carbides might remain unoxidized through many geologic ages, to be reached by percolating waters at the present day. The development of hydrocarbons would then inevitably follow, although to what extent they might be subse- quently consumed no one can say. The theory is plausible, but is it capable of proof? Furthermore, does it account for any accumula- tions of petroleum such as yield the commercial oils of to-day? These essential questions are too often overlooked, and yet they are the main points at issue. We may admit that hydrocarbons are formed within volcanoes, but the quantities definitely traceable to such a source are altogether insignificant. Bitumens occur in small amounts in many igneous rocks, but never in large volume. They are, moreover, absent, at least in significant proportions, from the Archean, and first appear abundantly in Paleozoic time. From the Silurian upward they are plentiful, and commonly remote from great indications of volcanic activity. Even such an occurrence as that of the Pitch Lake in Trinidad, where asphalt is associated with thermal waters, does not necessarily imply a community of origin. It-is at least conceivable that the solfataric springs may have acted upon sedimentary accumulations of oil, partly by vaporizing the latter and 1 See F. Wohler, Liebig’s Annalen, vol. 109, 1859, p. 349, on carbon compounds in the meteorite of Kaba, Hungary. Also S. Meunier, Compt. Rend., vol. 109, 1889, p. 976, on the meteorite of Mighei, Russia. A. E. Nordenskiold (Poggendorf’s Annalen, vol. 141, 1870, p. 205) found carbonaceous matter in the meteorite of Hessle, Sweden; and G. Tschermak(Sitzungsb. K. Wiss. Akad. Wien, vol. 62, Abth. 2, 1870, p. 855) reports 0.85 per cent of a hydrocarbon in the stone which fell at Goalpara, India. The well-known meteors of Orgueil, France, and Cold Bokkeveld, South Africa, were largely carbonaceous. On Orgueil, see S. Cloez, Compt. Rend. , vol. 59, 1864, p. 37. Graphite and amorphous carbon are common in meteorites, and in some falls diamonds have been found. 2 Chem. News, vol. 64, 1891, p. 14. A criticism by Redwood appears on p. 215. 3 M6m. Soc. ingen. civils France, October, 1903, p. 346. THE NATURAL HYDROCARBONS. 729 so bringing it to the surface, and partly by effecting, with the aid of steam and sulphur, the condensations or polymerizations that are observed. These considerations serve to show the need of great caution in dealing with this class of problems and to warn us against hasty generalizations. Speculations based upon individual occur- rences of petroleum are of very little value. The entire field, in all of its complexity, must be taken into account. Admitting that methane is sometimes formed as a volcanic emana- tion, we must also recognize the fact that it is more commonly of organic origin. Its popular name, “ marsh gas,” is verbal evidence of its derivation from decaying vegetation. Ordinarily, it is gener- ated in apparently small amounts, but gas in Iowa wells has been described 1 which occurs in the drift and seems to be of vegetable origin. Buried vegetation alone can account for its development under the observed conditions. Apart from the natural occurrences of marsh gas, either in swamps or as the “fire damp” of coal mines, its artificial production has been studied experimentally. F. Hoppe-Seyler 2 and H. Tappeiner 3 have shown that it is formed by the fermentation of cellulose, together with carbon dioxide and free hydrogen. During the decay of sea- weeds, however, according to F. C. Phillips , 4 a little methane is at first evolved, the generated gases consisting largely of carbon dioxide, hydrogen, and nitrogen. The apparatus in which the experiment was performed was allowed to stand in position for two and a half years, and during that time, following the first rapid evolution of gas, a very slow, continuous production was observed. At the end of the period the gas consisted of methane. Phillips concludes, from this evidence, that buried vegetable matter, after a brief era of rapid gas evolution, may pass into a condition of extremely slow decay when methane is generated. It is possible, however, that methane is not the only hydrocarbon thus produced. From data of this kind, and from the experiments cited in the pre- ceding section of this chapter, it is evident that hydrocarbons analo- gous to natural gas, petroleum, and asphalt may be derived either from animal or vegetable matter, or from both. This, I think, admits of no dispute, but argument is possible relative to the genesis of the larger accumulations of mineral oil. Engler’s researches have led to a widespread belief in the animal origin of petroleum, although the details of the transformation process are very diversely 1 See A. G. Leonard, Proc. Iowa Acad. Sci., vol. 4, p. 41. F. M. Witter (Am. Geologist, vol. 9, 1892, p. 319) has described a gas well, about 100 feet deep, near Letts, Iowa. 2 Ber. Deutsch. chem. Gesell., vol. 16, 1883, p. 122. 3 Idem, pp. 1734, 1740. See also L. Popoff, abstract in Jour. Chem. Soc., vol. 28, 1875, p. 1209, on gas from river mud near sewer openings. 4 Am. Chem. Jour., vol. 16, 1894, p. 427. 730 THE DATA OF GEOCHEMISTRY. interpreted. 1 Engler 2 himself ascribes the derivation of petroleum from animal remains to a putrefactive process, which removes the nitrogen compounds. The fats remain, to be altered by heat and pressure 3 into hydrocarbons, whose boiling points lie below 300°; and these later undergo a partial autopolymerization into denser forms. How far such a polymerization may be possible, if indeed it is possible at all, is a matter of uncertainty. C. F. Mabery 4 holds that the changes are always in the opposite direction and that the more complex hydrocarbons are formed first, partially breaking down afterward into lower members of the series. J. Marcusson 5 holds the same view. The putrefactive removal of the albuminoid substances is also to be questioned, and it is certainly not universal. The nitrogen bases of California petroleum furnish perhaps the strongest evidence that the proteids contribute their share to the make-up of petroleum, and show also that these particular oils are of animal origin. Several other writers have brought evidence to bear in favor of the derivation of petroleum from fish remains. Dieulafait 6 observed that the copper shales of Mansfeld are strongly impregnated with bitumen, and also rich in fossil fish. The petroleum of Galicia is always associated with menilitic schists in which fish remains are peculiarly abundant. C. Engler 7 cites some computations by Szaj- nocha, to the effect that the annual catch of herring on the north coast of Germany would, if its fats were half converted into petro- leum, yield in 2,560 years as much oil as Galicia has produced. G. A. Bertels, 8 on the other hand, attributes the Caucasian petroleums to the decomposition of mollusks. In the Kuban district, the oil, 1 For a very complete summary of all the hypotheses relative to the formation of petroleum, see Hofer, Das Erdol, 1906, pp. 160-229. See also Redwood, Petroleum and its products, vol. 1, 1906, pp. 250-261. Other summaries are by Aisinmann, Zeitschr. angew. Chemie, 1893, p. 739; idem, 1894, p. 122; C. Element, Bull. Soc. beige geol., vol. 11, proc. verb., 1897, p. 76; R. Zuber, Zeitschr. prakt. Geologie, 1898, p. 84; and E. Orton, Bull. Geol. Soc. America, vol. 9, 1897, p. 85. Very recent memoirs on the subject are by P. De Wilde, Arch. sci. phys. nat., 4th ser., vol. 23, 1907, p. 559, and C. Neuberg, Sitzungsb. K. Akad. Wiss. Berlin, May 16, 1907. 2 Ber. Deutsch. chem. Gesell., vol. 30, 1897, p. 2358. For more recent articles by Engler see Zeitschr. angew. Chemie, vol. 21, 1908, p. 1585; Verhandl. naturwiss. Vereins, Karlsruhe, 1908, vol. 20, p. 65; and Compt. rend. Cong, internat. petrole, Bucarest, 1910, vol. 2, p. 1. The last-named volume contains many papers on various subjects relating to petroleum. 3 The importance of pressure in petroleum formation was also urged by G. Kramer and W. Bottcher (Ber. Deutsch. chem. Gesell., vol. 20, 1887, p. 595), in their comparison of the hydrocarbons contained in petroleum and coal oil or tar. H. Monke and F. Beyschlag (Zeitschr. prakt. Geologie, 1905, pp. 1, 65, 421) emphasize the putrefactive process, which yields petroleum, as compared with the carbonizing process, which forms coal. 4 Jour. Am. Chem. Soc., vol. 28, 1906, p. 429. 6 Chem. Zeitung, vol. 30, 1906, p. 788. 6 Cited by A. Jaccard, Arch. sci. phys. nat., 3d ser., vol. 24, 1890, p. 106. 7 Ber. Deutsch. chem. Gesell., vol. 33, 1900, p. 16. See also Cong, internat. du p6trole, 1900, p. 30. 8 Cited by Hofer, Das Erdol, 1906, p. 219. F. Hornung (Zeitschr. Deutsch. geol. Gesell., vol. 57, Mo- natsb., 1905, p. 534) argues in favor of fishes as the raw material of petroleum. See also J. J. Jahn, Jahrb. K.-k. geol. Reichsanstalt, vol. 42, 1892, p. 361. For arguments against the theory of Engler, see D. Pan- tanelli, Bull. Soc. geol. ital., vol. 25, 1906, p. 795. Pantanelli seems to favor the inorganic origin of petro- leum. W. Ipatief (Jour, prakt. Chem., ser. 2, vol. 84, 1911, p. 800) favors the organic origin. THE NATURAL HYDROCARBONS. 731 accompanied by salt water, exudes directly from beds of molluscan remains, which occur in enormous quantities. Engler, of course, was not the first to advocate a derivation of petroleum from animal remains. His views have received special attention because of their experimental basis. C. Ochsenius, 1 for instance, has sought to connect the formation of petroleum with that of the mother-liquor salts which accumulate during the last stage of the evaporation of sea water. According to this writer, petroleum is generated from marine organisms, preferably the larger forms, which are buried beneath air-tight sediments and slowly acted upon by the above-named saline residues. As an argument in favor of this hypothesis, he calls attention, as many others have done, to the common association of brine with petroleum, and cites analyses of such waters. This association of salt and oil is strongly emphasized by L. Mrazec 2 in his studies of Roumanian petroleum. F. Heusler 3 also, while indorsing Engler’ s principal conclusions, invoked the aid of aluminum chloride as an agent in effecting a polymerization of the hydrocarbons. According to Ochsenius’s theory, magnesium chloride was the active substance. These sug- gestions are of very little value, for the reason that the laboratory reactions with aluminum chloride are effected with the anhydrous salt and not with its hydrolyzed aqueous solutions. It is not shown experimentally that the latter would be effective, nor does aluminum chloride occur in any notable quantity in natural waters. 4 A more probable function of the salts, according to R. Zaloziecki, 5 is to retard and modify the decay of animal matter on or near the seashore, and so to give time for its transformation into petroleum. The latter process need not be very slow, for E. Sickenberger 6 has shown that in small bays of the Red Sea, where the salinity reaches 7.3 per cent, petroleum is actually forming as a scum upon the surface of -the water. Living forms are abundant in these bays, and their remains, after death, furnish the hydrocarbons. The latter are to some extent absorbed into the pores of coral reefs, and so contribute to the forma- tion of bituminous limestones. A still earlier publication by O. F. Fraas, 7 contains data of similar purport. Fraas found in Egypt 1 Chem. Zeitung, vol. 15, 1891, p. 935, and Zeitschr. Deutsch. geol. Gesell., vol. 48, 1896, p. 239. See also his papers cited in Chapter VII, ante. 2 Compt. rend. Cong, intemat. petrole, Bucarest, 1910, vol. 2, p. 80. Also L’industrie du petrole en Roumanie, Bucarest, 1910. The presence of methane, ethane, etc., in rock salt has been studied by N. Cost&chescu, Annales sci. Univ. Jassy, vol. 4, 1906, p. 3. On the animal origin of petroleum see also L. Singer, Inaug. Diss., Zurich, 1893. 3 Zeitschr. angew. Chemie, 1896, pp. 288, 318. * A possible exception to this statement is cited by Ochsenius (Zeitschr. Deutsch. geol. Gesell., vol. 48, 1896, p. 239), who mentions a water containing, in its solid residue, 23.91 per cent of AICI 3 . This water accompanied a petroleum. 3 Chem. Zeitung, vol. 15, 1891, p. 1203. « Idem, p. 1582. 1 Bull. Soc. sci. nat. NeucMtel, vol. 8, 1868, p. 58. See also F. C. Phillips, Proc. Am. Philos. Soc., vol. 36, 1897, p. 121, on petroleum inclosed in fossils. 732 THE DATA OP GEOCHEMISTRY. shells filled with bitumen, and noticed that the bituminous beds were rich in fossils, while the nonbituminous strata were poor. In the region of the Dead Sea, also, Fraas noticed that bitumen was abundant in beds of baculites, from which it exudes to accumulate upon the shore. In this connection it may well be noted that the brines which are so often associated with petroleum have, as a rule, a composition indicative of a marine origin, and do not resemble solfataric or vol- canic waters . 1 Furthermore, Mendel eefs objection to the possibility of forming petroleum at the bottom of the sea — namely, that being lighter than water it would float away and be dissipated — is not only negatived by Sickenberger’s observations, but also by the well-known fact that mud and clay are capable of retaining oily matters mechan- ically. The littoral sediments probably aid in the process of petro- leum formation, if only to the extent of retaining the fatty substances from which the oil is to be produced. The beds of sulphur which occur adjacent to some oil wells, notably in Texas, were probably formed by the reducing action of organic matter upon sulphates, such as gypsum, a mineral which is often associated with marine deposits and with petroleum. The association of gas, oil, salt, sulphur, and gyp- sum, which some writers have taken as evidence of former volcanism, is much more simply interpreted, both chemically and geologically, as due to the decomposition of organic matter in shallow, highly saline waters near the margin of the sea. The derivation of petroleum from vegetable remains has had many advocates, although the hypotheses have not all been framed on the same lines. L. Lesquereux , 2 studying the Devonian oils of the eastern United States, argued in favor of their derivation from cellular marine plants, especially fucoids, whose remains abound in the petro- liferous formations. Ligneous or fibrous plants, on the other hand, yield coal.* This hypothesis led Youga 3 to suggest that great masses of fucus, like those of the Sargasso Sea, might sink to the bottom of the ocean, and there, decomposing under pressure, could yield petro- leum. Redwood 4 states that the salt marshes of Sardinia are some- times covered by sheets of seaweed, which are in process of decompo- sition into an oily substance resembling petroleum, and similar occur- rences have been noted on the coast of Sweden. These phenomena are probably not exceptional, and deserve a more precise examination than they have received hitherto. An observation by W. L. Watts 5 1 The waters accompanying the naphtha of the Grosny district, Russia, as analyzed recently by K. Charitschkoff (Chem. Zeitung, 1907, p. 295), appear to be exceptional. In these sodium carbonate is more abundant than the chloride, and salts of ammonium and the amines are also present. 2 Bull. Soc. sci. nat. Neuchatel, vol. 7, 1866, p. 234. 3 See discussion following Lesquereux’s communication. * Petroleum and its products, 2d ed., vol. 1, pp. 126, 142. 6 Bull. California State Min. Bur. No. 19, p. 202. See also Bull. No. 3 for more details. In Bull. No. 16, 1899, A. S. Cooper discusses at length the genesis of petroleum and asphalt in California. Bulls. Nos. 31 and 32 also relate to this subject. THE NATURAL HYDROCARBONS. 733 • that the saline waters associated with petroleum in the central valley of California are unusually rich in iodine appears to have some relation to this class of hypotheses. Watts connects this iodine with the familiar content of iodine in seaweed, and regards the latter as a probable source of this particular oil. Data of this class might be multiplied almost indefinitely. For instance, C. E. Bertrand and B. Kenault 1 have shown that Boghead mineral, torbanite, and kerosene shale, from which oils are distilled, are derived from gelatinous algae, whose remains are embedded in what was once a brown humic jelly. This observation may be cor- related with the views advanced by J. S. Newberry 2 and S. F. Peck- ham, 3 who regard the liquid petroleums as natural distillates from carbonaceous deposits, which latter were laid down at depths below the horizons where the oil is now found. The heat generated during metamorphism is supposed to be the dynamic agent in this process, although many productive regions show no evidence that any violent metamorphoses have ever occurred. 4 In 1843 E. W. Binney and J. H. Talbot 5 reported a peculiar occur- rence of petroleum permeating a peat bog, Down Holland Moss, not far from Liverpool, England. The origin of this oil was obscure, but was attributed by the authors to an alteration of the peat itself, a mode of genesis which later writers have doubted. J. S. New- berry, 6 however, states that in the Bay of Marquette, where the shore consists of peat overlying Archean rocks, bubbles of marsh gas arise, together with drops which cover the surface of the water, in spots, with an oily film. The following investigations seem to bear upon the problems suggested by these observations : In 1899 A. F. Stahl 7 and, independently, G. Kramer and A. Spil- ker 8 called attention to a possible derivation of petroleum from diatoms, which abound in certain bogs. These organisms, accord- ing to Kramer and Spilker, contain drops of oily matter, and from diatomaceous peat a waxy substance, resembling ozokerite, can be extracted. 9 The theory, based upon these data, is briefly as fol- lows : A lake bed becomes filled in time with diatomaceous accumu- lations, over which a cover of other growths or deposits is formed. 1 Compt. Rend., vol. 117, 1893, p. 593. See also Bertrand, Compt. rend. VIII Cong. geol. internat., 1900, p. 458. According to E. C. Jeffrey (Proc.Am. Acad. Arts and Sci., vol. 46, 1910, p. 273), the supposed gelat- inous algae are the spores of vascular cryptogams. 2 Geology of Ohio, vol. 1, 1873, p. 158. See also an earlier paper by Newberry, Rock oils of Ohio, in Four- teenth Ann. Rept. Ohio State Board Agr., 1859, p. 605. 2 Proc. Am. Philos. Soc., vol. 10, 1868, p. 445; vol. 37, 1898, p. 108. * H. Stremme (Centralbl. Min., Geol. u. Pal., 1908, p. 271) has shown that the polymerization of petroleum may itself generate heat. 6 Published in Trans. Manchester Geol. Soc., vol. 8, 1868, p. 41. Curiously, a later paper by Binney appears earlier, namely, in vol. 3, 1860, p. 9. 6 Annals New York Acad. Sci., vol. 2, 1882, p. 277. 1 Chem. Zeitung, vol. 23, 1899, p. 144. Also note in vol. 30, 1906, p. 18. 8 Ber. Deutsch. chem. Gesell., vol. 32, 1899, p. 2940; vol. 35, 1902, p. 1212. Criticism by Engler in vol. 33, 1900, p. 7. 9 See also C. E. Guignet, Compt. Rend., vol. 91, 1880, p. 888, on wax from peat. T34 THE DATA OF GEOCHEMISTRY. By decay of the organic substances, ammonium carbonate is pro- duced, which hydrolyzes the wax, and from the resulting acid carbon dioxide, carbon monoxide, and water are gradually ehminated. Ozokerite is thus formed, which, at moderate temperatures and under pressure, becomes converted into liquid petroleum. With higher temperatures and pressures, in presence of sulphur, heavier oils and asphalt may be generated. In support of this hypothesis the authors describe a lake bed, near Stettin, which is about 23 feet thick and consists chiefly of diatoms. This deposit yields a wax con- taining over 10 per cent of sulphur, and from it a hydrocarbon, resembling the lekene from ozokerite, was isolated. Kramer and Spilker’s views have not met with very general acceptance, but they seem to contain elements of value. H. Potonie’s hypotheses, 1 for example, seem to be a broadening of Kramer and Spilker’s. This writer calls attention to the “faulschlamm” or “sapropel,” a slime, rich in organic matter, which is formed from gelatinous algse, and accumulates at the bottom of stagnant waters. Such a slime, Potonie believes, may be the parent substance from which bitumen, by a process of decay, was probably derived. In this connection, and with reference to the adequacy of the proposed source, it is well to remember the enormous accumulation of “ oozes,” namely, the radiolarian and globigerina oozes, on the bottom of the sea. The organic matter thus indicated is certainly abundant enough, if it can decay under proper conditions, to form more hydrocarbons than the known deposits of petroleum now contain. 2 These remarks upon the oceanic sediments at once suggest an inter- mediate group of hypotheses, which assume a mixed origin for petro- leum. Animal matter in some cases, vegetable matter in others, or both together, are supposed to be the initial source of supply. A. Jaccard, 3 for example, argues that the liquid oils are derived from marine plants, while the viscous or solid bitumens may originate from mollusks, radiates, etc. Some oils, again, are supposed to be of mixed origin, and it would seem probable that the last class is the most common. Ideas of this kind have repeatedly been enunciated with reference to American petroleums — that of Pennsylvania being attributed to marine vegetation, that of California to animal remains. 1 Natur. Wochenschr., vol. 20, 1905, p. 599. 2 These oceanic sediments are especially noticed by Engler in a paper read before the petroleum congress in 1900 (Cong, intemat. du pdtrole, Paris, 1900, p. 28). In A. Beeby Thompson’s monograph, The oil fields of Russia, London, 1904, pp. 85-87, a theory is developed to account for the probable formation of bitumens on the sea bottom. Thompson regards fish remains as an important source of supply. G. P. Mikhailovski (Bull. Com. g6ol. St. Petersburg, vol. 25, 1908, p. 319) derives the Caucasian petroleum from marine sedi- ments. C. B. Morrey (Bull. Geol. Survey Ohio, No. 1, 1903, p. 313) suggests that bacteria have been the chief agents in transforming other organic matter into hydrocarbons. 3 Eclog. Geol. Helvet., vol. 2, 1890, p. 87. See also Arch. sci. phys. nat., 3d ser., vol. 23, 1890, p. 501; vol. 24, 1890, p. 106. Jaccard studied especially the bitumens of the Jura. THE NATURAL HYDROCARBONS. 735 The American literature of petroleum is rich in suggestions of this order. 1 It has long been known that some petroleums are optically active; that is, they are able to rotate a ray of polarized light, sometimes to the right and sometimes to the left. This, according to P. Walden, 2 gives us an important datum toward determining the origin of petroleum. Only the oils derived from organic matter, Walden asserts, can possess this property, the hydrocarbons prepared from inorganic materials, such as metallic carbides, being optically inert. The oils distilled from coal, which is evidently of vegetable origin, are active; and petroleum, which has the same peculiarity, is presum- ably formed from similar materials. The activity is attributed by some writers to derivatives of cholesterin, of animal origin, or else to its vegetable equivalent, phytosterin. 3 Apart from this detail the general conclusions are exceedingly important, but need to be more thoroughly tested before they can demand universal acceptance. The presumption, however, is strongly in their favor. In any attempt to discover the genesis of petroleum the quantita- tive adequacy of the proposed sources must be taken into account. In such an inquiry superficial observations are deceptive, for one is apt to overrate the visible and productive accumulations which fur- nish the oils of commerce. These seem large, but they are relatively insignificant. As Orton 4 has said, disseminated petroleum is well- nigh universal; the accumulations are rare. In certain districts the shales and limestones are generally impregnated with traces of bitu- mens, which seem at first sight to be insignificant, but which really represent enormous quantities. In the Mississippian (“sub-Carbo- niferous”) limestones of Kentucky petroleum is generally present. If it amounts to only 0.10 per cent, each square mile of rock, with a thickness of 500 feet, would yield about 2,500,000 barrels of oil. Even more striking are the figures given by T. Sterry Hunt, 5 6 who 1 In addition to the memoirs already cited, see the reports of the Second Geol. Survey Pennsylvania. Also J. A. Bownocker, Geol. Survey Ohio, 4th ser., Bull. No. 1, 1903; S. S. Gorby, Sixteenth Aim. Rept. Indiana Dept. Geol. and Nat. Hist., 1888; W. S. Blatchley, idem, Twenty-eighth Ann. Rept., 1904; E. Haworth, Kansas Univ. Geol. Survey, vol. 1, 1896, p. 232; H. P. H. Brumell, Geol. Survey Canada, new ser., Ann. Rept. 5, Q, 1893; and W J McGee, Eleventh Ann. Rept. U. S. Geol. Survey, pt. 1, 1891, p. 589. L. Harperath (Bol. Acad. nac. cien. Cordoba (Argentina), vol. 18, 1905, p. 153) has published a long memoir on petroleum and salt. L. V. Dalton (Econ. Geology, vol. 4, 1909, p. 603) advocates the organic origin of petroleum. 2 Chem. Zeitung, vol. 30, 1906, pp. 391, 1155, 1168. Walden cites many examples of this optical activity. See also Engler, idem, p. 711, and F. W. Bushong, Science, vol. 38, 1913, p. 39. 3 See M. Rakusin, Chem. Zeitung, vol. 30, 1906, p. 1041; Ber. Deutsch. chem. Gesell., vol. 42, 1908, pp. 1211, 1640, 4675; J. Marcusson, Chem. Zeitung, vol. 31, 1907, p. 419; vol. 32, 1908, pp. 377, 3917 R. Albrecht, Inaug. Diss., Karlsruhe, 1907; L. Ubbelohde, Ber. Deutsch. chem. Gesell., vol. 42, 1909, p. 3242; vol. 43, 1910, p. 608. R. Zaloziecki and H. Klarfeld (Chem. Zeitung, vol. 31, 1907, pp. 1155, 1170) question the cholesterin theory and favor that of PotoniA See also Zaloziecki, Compt. rend. Cong, internat. pArole, Bucarest, 1910, p. 718. 4 First Ann. Rept. Geol. Survey Ohio, 1890, chapter 11; Geol. Survey Kentucky, Report on occurrence of petroleum, etc., 1888-89. 6 Chemical and geological essays, 1875, p. 168. 736 THE DATA OF GEOCHEMISTRY. estimates that in the limestone of Chicago, with a thickness of 35 feet, there are 7,743,745 barrels of oil to each square mile of territory. Figures like these, together with the computations, previously cited, made by Szajnocha relative to Galician petroleum, lead to the con- viction that the formation of bitumens is a general process and by no means exceptional. Wherever sediments are laid down, inclosing either animal or vegetable matter, there bitumens may be produced. The presence of water, preferably salt, the exclusion of air, and the existence of an impervious protecting stratum of clay seem to be essential conditions toward rendering the transformation possible. Seaweeds, mollusks, crustaceans, fishes, and even microscopic organ- isms of many kinds may contribute material to the change. In some cases plants may predominate; in others animal remains; and the character of the hydrocarbons produced is likely to vary accord- ingly, just as petroleum varies in different fields. In one region we find chiefly paraffins, in another naphthenes, and in another nitroge- nous or sulphureted oils. Such differences can not be ignored, and they are most easily explained on the supposition that different materials have yielded the different products. On this class of prob- lems the chemist, the geologist, and the paleontologist must work together. Physics also is entitled to be heard; for, as D. T. Day 1 has shown, petroleum, by simple filtration through fuller’s earth, can be separated into fractions which differ in density and viscosity and are therefore of different composition. Such a filtration, or, more precisely, diffusion, must take place in nature wherever migrating hydrocarbons traverse permeable strata. By whatever class of reactions petroleum is generated, it doubtless appears first in a state of dissemination. How does it become con- centrated ? This question does not fall within the domain of chem- istry, and can not be properly discussed here. 2 Probably circulating waters have much to do with the process, but whatever that may be the laws governing the motion of liquids must inevitably rule. The oils must gather in proper channels, moved by gravitation, or by hydrostatic pressure of waters behind or below them, or by the pres- sure of dissolved and compressed gases, and they accumulate in porous rocks or cavities under layers of impervious material. When the latter are lacking, or when the hydrocarbons enter large areas of porous rocks, they may be either evaporated or rediffused. Pressure, temperature, viscosity, and the character of the surrounding rocks 1 Cong, intemat. p^trole, Paris, 1900, p. 53. See also J. E. Gilpin and O. E. Bransky, Am. Chem. Jour., vol. 44, 1910, p. 251; and Gilpin and P. Schneeberger, Am. Chem. Jour., vol. 50, 1913, p. 59. These authors show that fuller’s earth exerts a selective absorption for unsaturated hydrocarbons and organic sulphides. 2 For a discussion of this problem, see H. Hofer, Das Erdol, 1906, p. 223. Also G. I. Adams, Trans. Am. Inst. Min. Eng., vol. 33, 1903, p. 340; and D. T. Day, idem, p. 1053. Orton’s reports, previously cited, contain important contributions on this theme. THE NATURAL HYDROCARBONS. 737 must all be taken into account, and each productive area needs to be studied independently with reference to its local conditions. In conclusion, I may be allowed to suggest that nearly all of the proposed theories to account for the origin of petroleum embody some elements of truth. Sokoloff’s cosmic hypothesis is sustained by the fact that hydrocarbons are found in meteorites. The volcanic hypothesis is sustained by the fact that hydrocarbons occur among volcanic emanations. The organic origin of petroleum, however, seems to be best supported by the geologic relations of the hydrocar- bons, which are found in large quantities only in rocks of sedimentary character. Any organic substance which becomes inclosed within the sediments may be a source of petroleum, and when the latter happens to be rich in nitrogen, animal matter was probably the initial material. There is no evidence to show that any important oil field derived its hydrocarbons from inorganic sources . 1 i The controversies relative to the genesis of petroleum have created a voluminous literature, of which only the main points have been considered here. For an excellent summary of the subject, see Engler and Hofer’s great treatise Das Erdol, vol. 2, Leipzig, 1909, pp. 59-142. On the genetic relations between petroleum and coal see David White, Jour. Washington Acad. Sci., vol. 5, 1915, p. 189. 97270°— Bull. 616—16 47 CHAPTER XVII. COAL. ORIGIN OF COAL. Although doubts may exist as to the origin of petroleum, there are none whatever as to the essential origin of coal. It is obviously de- rived from vegetable matter, by a series of changes which are plainly traceable, even though their mechanism is not fully understood. Vegetation, peat, lignite, soft coal, anthracite, and some graphitic minerals form a series of substances which grade one into another in an unbroken line, reaching from complex organic, oxidized com- pounds at one end to nearly but not quite pure carbon at the other. All these bodies, except perhaps the last, are indefinite mixtures which vary in composition, and it is therefore impracticable to write chemical equations that shall properly represent their transforma- tions. Such equations, to be sure, have been suggested and written, but they embody fallacies which are easily exposed. They start from the assumption that the principal initial compound contained in vegetation is cellulose, a definite carbohydrate of the formula C 6 H 10 O 5 , which gradually loses carbon dioxide, marsh gas, and water, and so yields the series of products represented by the different kinds of coal . 1 This assumption, like most other assumptions of its class, is partly true and partly false. Cellulose is an important constituent of vegetable matter, but it stands by no means alone. When it decays, it loses the substances named above and it also undergoes other changes which are difficult to measure. In every swamp or peat bog the waters are charged, more or less heavily, with soluble organic matter of which the written reactions take no account. This soluble matter is found in the waters of all bogs and streams, and it is just as much a factor in the real reactions as are the gaseous prod- ucts or the solid carbonaceous residues. If, instead of the composition of cellulose, we begin with the com- position of wood, we shall have a better starting point for our series of derivatives. Wood or woody fiber is by no means the only sub- stance to be considered, but it is the most important one, and its 1 The formula C 6 H 10 O 5 represents only the empirical composition of cellulose, and not its true molecular weight. According to A. Nastukofl (Ber. Deutsch. chem. Gesell., vol. 33, 1900, p. 2237), the true formula is probably 4 OC 6 H 10 O 5 , or C 240 H 400 O 200 . This may be an exaggeration, but the molecular weight of cellulose is certainly high. For an attempt to write chemical equations representing coal formation, see J. F. Hoff- mann, Beitr. Geophys., vol. 7, 1905, p. 327. 738 COAL. 739 ultimate composition has been well determined. Its proximate com- position is not so clearly known, but certain available facts are per- tinent to the present discussion. It contains cellulose, C 6 H 10 O 5 , and a substance known as lignone, lignin, or lignocellulose, in about equal proportions, together with other minor organic constituents, such as gums and resins, 1 and some inorganic matter which forms its ash. To lignocellulose, according to Cross and Bevan, 2 the formula C 12 H 18 0 9 may be assigned; and it is best represented by jute fiber, which consists almost wholly of this substance. If, now, we compare the percentage composition of cellulose, ligno- cellulose, and wood, we shall see how unsafe it is to write equations intended to show the derivation of coal upon the basis of either defi- nite compound alone. The data are as follows: Composition of cellulose , lignocellulose , and wood. A. The composition of cellulose, calculated from its formula. B. The composition of lignocellulose, similarly computed. C. The average composition of twenty-four woods, analyzed by Petersen and Schodler, Liebig’s Anna- len, vol. 17, 1836, p. 139. Samples dried and finely powdered. D. Average of thirty-six analyses of five different woods, by E. Chevandier, Annales chim. phys., 3d ser., vol. 10, 1844, p. 129. Samples dried in vacuo at 140°. E. Average of eight analyses of woods by W. Baer, Jahresb. Chemie, 1847-48, p. 1112. Ash from 0.53 to 2.03 per cent. F. Average of seven Danish woods, analyzed by E. Gottlieb, Jour. Chem. Soc., vol. 46, 1884, p. 477 (abstract). Dried at 115°. G. Average composition of five acrogen plants, of the genera Lycopodium, Equisetum, Aspidium, and Cyathea, by G. W. Hawes, Am. Jour. Sci., 3d ser., vol. 7, 1874, p. 585. In Equisetum the ash ran as high as 11.82 per cent. A B C D E F G c 44. 43 47. 06 49. 31 51. 21 49. 16 49. 76 48. 83 H 6. 22 5. 89 6. 29 6. 24 6. 10 6. 14 6. 37 O 49. 35 47. 05 44. 40 42. 55 44. 74 44. 10 44. 80 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 All of these analyses are recalculated to an ash-free basis. In the table, for uniformity, the nitrogen is added to the oxygen. Chevan- dier found, in mean, 1.10 per cent of nitrogen in his woods, but Gott- lieb obtained only 0.04 to 0.10. In Hawes’s analyses the nitrogen ranged from 1.21 to 2.17 per cent. The differences between the wood analyses are principally due to differences in drying. From these figures we see that cellulose contains about 5 per cent more oxygen than carbon, while in wood the reverse statement is very nearly true. Even lignocellulose contains less carbon than is actually found in wood. The figures for wood given in column F approximate very nearly to the formula C 6 H 9 0 4 , and that expression might be 1 See M. Singer, Monatsh. Chemie, vol. 3, 1882, p. 395, on the subordinate constituents of wood. The subject is one which can not be properly developed here. 2 Jour. Chem. Soc., vol. 55, 1889, p. 199. 740 THE DATA OF GEOCHEMISTRY. used were wood a definite substance. Its employment, however, is more likely to cause misapprehension than to aid in the elucidation of problems. At best it can only be taken as a convenient collocation of symbols, more easily borne in mind than the actual percentages. It is generally admitted, I think, by all competent investigators that coal originated from vegetation which grew in swampy or marshy places. As the vegetation died it underwent a partial decay and was buried under successive layers, either of matter like itself or else of sediments such as clay. In that way it was protected from complete atmospheric oxidation and at the same time subjected to a gradually increasing pressure and doubtless to some heat gener- ated thereby. The vegetation was of many kinds — trees, ferns, grasses, sedges, mosses, etc. — and these all contributed variously to the formation of the future coal. Trees standing erect within a bed of coal, their roots still remaining embedded in an underlying stratum of clay, tell a part of the story. Fossil ferns, and even the remains of microorganisms, also add their testimony to what has occurred. In some cases beds of lignite represent submerged forests; and in others, as shown by many geologists, the coal was probably formed, not from vegetation in place, but from drifted materials, a condition, however, which does not affect the chemistry of the carbonizing process. The slow decay of the buried substances is the essential thing for the chemist to consider. With the vegetable matter some animal remains were undoubtedly commingled, helping to increase the nitrogen content of the coal; and the ash of the latter was augmented by more or less inorganic sediment, derived from the wash of the land in times of flood. Certain coals and carbonaceous rocks, such as cannel, Boghead, oil shale, etc., are attributed by H. Potonie 1 to the decomposition of “sapropel,” a sort of slime made up largely of gelatinous algae, mixed with some animal remains. This view has received much acceptance, but E. C. Jeffrey 2 has shown that in some cases at least the supposed fossil algae are really the spores of vascular cryptogams. In their memoir on the origin of coal D. White and R. Thiessen 3 give an excellent summary of the diverse theories upon the subject. Their conclusions, based on field studies and microscopic investiga- tions, are that “ all coal was laid down in beds analogous to the peat beds of to-day.” They regard it as “ chiefly composed of residues consisting of the most resistant components of plants, of which 1 Die Entstehung der Steinkohle, Berlin, 1910. See also citation in the preceding chapter and the refer- ences to the work of Bertrand and Renault. Also H. Stremme, Monatsber. Deutsch. geol. Gesell., vol. 59, 1907, p. 153. * Proc. Am. Acad. Arts and Sci., vol. 46, 1910, p. 273. For a recent paper by Jeffrey on the origin of coal see Jour. Geology, vol. 23, 1915, p. 218. 8 The origin of coal: Bull. U. S. Bin* *. Mines No. 38, 1913. Another important work on the subject is by O. Stutzer, Kohle (Allgemeine Kohlengeologie), Berlin, 1914. COAL. 741 resins, resin waxes, waxes, and higher fats, or the derivatives of the compounds comprising them are the most important.” The algal and gelosic theories of the origin of coal they dismiss as undemon- strated. The views of White and Thiessen probably represent the general consensus of opinion. A moment’s consideration will suffice to show that the process of vegetable decay could not have been uniform. The softer plant tissues decompose most rapidly; the more compact ligneous masses endure much longer. Even the trunks of trees must exhibit similar varia- tions, for woods differ in hardness and compactness, and the resinous varieties will rot the slowest of all. The resins themselves show the minimum of change, and where they were most abundant their fossil remnants are found. Amber, fossil copal, the waxes found in peat bogs, and a multitude of similar substances have been thus preserved. In lignite and bituminous coal aggregations and often large masses of resinous bodies not infrequently occur, and in a disseminated form, unrecognizable by the eye, they must be almost invariably present. Their quantity, of course, would depend upon the exact character of the vegetation from which a given coal bed was formed. The nature and distribution of the fossil resins deserve much more careful study than they have yet received. Much rarer than the resins are the salts of organic acids, which are sometimes found in coal, especially in lignite. Three of these are well-defined species, namely, whewellite, calcium oxalate; humboldtine, ferrous oxalate; and mellite, the aluminum salt of mellitic acid, A1C 6 0 6 .9H 2 0. Com- pounds of this class are significant in showing the range and variety of the reactions which take part in the formation of coal. Oxalic acid is easily formed from cellulose, and it is therefore surprising that its salts are not more frequently discovered in peat or coal. The soluble oxalates, of course, would be leached away; but calcium oxalate is insoluble and ought to be more common. In addition to its organic constituents coal also contains more or less inorganic matter which on combustion remains as ash. This was originally for the most part of sandy or clayey character, of variable composition; but rarer impurities are sometimes found. The occurrence of gold, silver, vanadium, and uranium was already noticed in Chapter XV of this work; and to these, according to Stutzer, molybdenum must be added. Stutzer 1 also mentions, as having been found in coal, millerite, cinnabar, chalcopyrite, bornite, spha- lerite, galena, and malachite. Pyrite or marcasite is commonly present, and often in annoying quantities. The almost omnipresent radium was detected in certain Alabama coals by S. J. Lloyd and J. Cun- ningham. 2 1 Op. cit., pp. 19, 193. 2 Am. Chem. Jour., vol. 50, 1913, p. 47. 742 THE DATA OF GEOCHEMISTRY. PEAT. The first stage in the development of coal from vegetable matter seems to be represented, at least approximately, by the formation of peat. The process, as observed, has already been outlined. Mosses, grasses, and other plants — any plants, in fact, which can thrive in marshes — grow, die, and are buried, layer after layer. On the sur- face of a bog we see the growing plants; a little below the surface, their recognizable remains; still deeper, we find a black, semigelati- nous substance from which the vegetable structure has largely dis- appeared. 1 This substance, saturated with moisture, is peat; dried, it becomes a valuable fuel. Many analyses of peat have been made, and, as might be expected, they vary widely. The following series by J. Websky 2 is especially suggestive. The samples were dried at 100°, and the analyses calcu- lated on an ash-free basis. Analyses of sphagnum and peat. A. Sphagnum, the chief plant of the peat bogs. B. Light peat, near surface. C. Light peat. D. Moderately light peat. E, F. Black peat. G. Heavy brown peat. A B C D E F G c 49. 88 50. 33 50. 86 59. 71 59. 70 59. 71 62. 54 H 6. 54 5. 99 5. 80 5. 27 5. 70 5. 27 6. 81 O 42. 42 42. 63 42. 57 32. 07 33.04 32. 07 29.24 N 1. 16 1. 05 .77 2. 95 1. 56 2. 95 1. 41 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 The progressive increase in carbon in passing from sphagnum to heavy peat is clearly shown. A few other analyses of peat maybe profitably cited, as follows: 3 1 On the rapidity of formation of peat, see a summary by G. H. Ashley, Econ. Geology, vol. 2, 1907, p. 34. 2 Jour, prakt. Chemie, vol. 92, 1864, p. 65. s For still other analyses, see Roth and Percy, as cited, and vol. 1 of Groves and Thorp’s Chemical tech- nology, pp. 14-20. In the latter work, p. 16, will be found 27 analyses of peat ashes, by Kane and Sullivan. Petersen and Nessler (Neues Jahrb., 1881, p. 82) give 17 ultimate analyses of German peat, with separate analyses of the ash. In a paper by H. B. Kiimmel (Econ. Geology, vol. 2, 1907, p. 24), there are many technical analyses of New Jersey peat, with calorimetric data. On the mechanism of peat formation, see N. S. Shaler, Sixteenth Ann. Rept. U. S. Geol. Survey, pt. 4, 1895, p. 305. An important general paper on peat, its rate of growth, its resins, etc., by R. Angus Smith, is given in Mem. Lit. Philos . Soc. Manchester, 1876, p. 281. See also T. R. Jones, Proc. Geologists’ Assoc., vol. 6, 1880, p. 207, and C. A. Davis, Rept. State Board Geol. Survey Michigan, 1906, p. 97, and Econ. Geology, vol. 5, 1910, p. 37. Davis also has a chapter on peat in White and Thiessen’s memoir. COAL. 743 Analyses of peat. A. From Th£sy, France. Analysis by Marsilly, Annales des mines, 5th ser., vol. 12, p.406. Dried 24 horns in vacuo. B. From Camon, France. Also by Marsilly, who gives seven analyses in all. Dried 24 hours in vacuo. C. From ‘‘Horin Schonen.” Analysis by O. Jacobsen, Liebig’s Annalen, vol. 157, 1871, p. 240. Dried at 100°. D. From a lake in Cashmere. Analysis by C. Tookey. See Percy’s Metallurgy, vol. 1, 1875, p. 206. E. Average of ten analyses cited by Roth, Allgemeine chemische Geologie, vol. 2, p. 642. A B c D E c 50. 67 46. 11 51. 38 37. 15 51. 97 H 5. 76 5. 99 6. 49 4. 08 6. 05 0 34. 95 35. 87 35. 43 23. 48 34. 02 N 1. 92 2. 63 1. 68 2. 02 1. 34 Ash 6. 70 9. 40 5. 02 33. 27 6. 61 100. 00 100. 00 100. 00 100. 00 100. 00 Reduced to an ash-free basis, in order to compare the organic mat- ter with that of wood, the analyses assume the following form: Analyses of peat reduced to ash-free basis. A B c D E C 54. 31 50. 89 54. 10 55. 67 55. 65 H 6. 18 6. 61 6. 83 6. 11 6. 48 O 37. 46 39. 58 37. 30 35. 19 36. 43 N 2. 05 2. 92 1. 77 3. 03 1. 44 100. 00 100. 00 100. 00 100. 00 100. 00 As compared with the data already given for wood, these figures show an increase in carbon, a decrease in oxygen, and a notable en- richment in nitrogen. The last gain may be partly from animal matter. The nature of the changes which have taken place in the transfor- mation of vegetable matter into peat is imperfectly understood. When ligneous fiber decays it yields an amorphous mixture of sub- stances which are known collectively as humus, and are partly of acidic nature. These substances are very ill-defined bodies, although various formulae have been assigned to them, but none can be said to be established. The acid portions dissolve in alkaline solu- tions, and so are partly washed away; but the salts formed with lime and iron, being insoluble, probably remain behind. The ash of peat is commonly rich in lime, not as carbonate, and also in iron, the latter appearing often in large beds of bog ore. The formation of the humus appears to take place by a fermentative process, which eliminates some carbon, hydrogen, and oxygen in the form of carbon dioxide, marsh gas, and water; and micro-organisms play some part in pro- ducing the changes observed. On this point, however, there is 744 THE DATA OF GEOCHEMISTRY. some doubt, Fruh and Schroter, 1 for example, regarding the microbian influence as very small. Broadly speaking, with temporary disregard of minor constitu- ents, a bed of peat may be said to consist of water, inorganic matter, vegetable fiber, and humus. From this point of view H. Borntrager 2 has made analyses of peat, finding in the black varieties from 25 to 60 per cent of humic substance, with 30 to 60 of fiber. Two of his analyses are as follows: Analysis of peat ( Borntrager ). A. Light-colored peat, Hannover. Mean of two analyses. B. Black peat, Oldenburg. A B Water 29. 50 20. 0 Ash 3. 05 3. 0 Fiber 54. 95 47. 0 Humus acids 12. 50 30.0 100. 00 100.0 In the light-colored peat evidently the changes have not gone so far as in the other. In some peat beds isolated masses of humic substance are found, to which the mineralogical name dopplerite has been given. 3 According to F. G. Kaufmann, 4 this substance is identical with the part of peat which dissolves in caustic alkali solutions, and he therefore regards peat as a mixture of dopplerite with partly decomposed vegetable matter. He gives analyses by Muhlberg of dopplerite from the peat of Obbiirgen, Canton Unterwalden, Switzerland, which, in mean, are as follows : Average composition of dopplerite. C 56. 46 H 5.48 O+N 38.06 100. 00 The organic portion of dopplerite from the original locality at Aussee, Styria, gave W. Demel 5 6 nearly identical results, and he assigns to the substance the formula C 12 H 14 0 6 . Its actual occur- rence in peat, however, is thought by Demel to be as a lime salt and not as the free organic acid. 1 Die Moore der Schweiz, Bern, 1904, a superb quarto monograph issued by the Swiss Geological Com- mission. See especially chapter 3, on peat. The volume contains a bibliography of 280 titles. On the microbian side of the question, see B. Renault, Compt. Rend., vol. 127, 1898, p. 825. 2 Zeitschr. anal. Chemie, vol. 39, 1900, p. 694; vol. 40, 1901, p. 639. 3 See Dana, System of mineralogy, 6th ed., p. 1014. For additional data on dopplerite, see C. Claesson, Chem. Zeitung, vol. 22, 1898, p. 523, and W. Alexejeff, Zeitschr. Kryst. Min., vol. 20, 1902, p. 187. * Jahrb. K.-k. geol. Reichsanstalt, vol. 15, 1865, p. 283. 6 Ber. Deutsch. chem. Gesell., vol. 15, 1882, p. 2961. COAL. 745 Peat also contains some ill-defined resinous substances, which are extractable by solution in hot ether or alcohol. In O. Jacobsen’s experiments 1 their quantity ran from 2.5 to 3.26 per cent. A crystal- line hydrocarbon, fichtelite, is sometimes found in the buried conifer- ous woods of peat beds. It appears to have been derived from the terpenes of the wood, but its exact nature is uncertain. 2 C. Hell assigned it the formula 3 C 30 H 54 , and L. Spiegel has argued in favor of C 18 H 30 . The possible derivation of petroleum-like hydrocarbons from peat was discussed in the preceding chapter. In its youngest forms peat is loosely compacted, but as it accumu- lates the under portions become compressed, and what was once a foot thick may shrink to 3 inches. 4 In various localities peat beds have been found buried beneath sediments or drift. Dawson 5 men- tions peat underlying bowlder clay in Cape Breton Island, and beds covered by drift have been reported in Iowa. 6 In all probability these occurrences are not exceptional, and the pressure developed by the covering material doubtless aids in the transformation of peat into coal. 7 LIGNITE. Under the names lignite and brown coal a number of substances are comprised which lie between peat on one side and bituminous coal on the other. The names are conventional and not always appropriate, for some lignites are not ligniform, and others are not brown, but black. Geologically, they are modern coals, Tertiary and Mesozoic, and their composition bears some relation to their age. The most recent approach peat; the oldest are nearer the true coals. This is a general, not an absolute relation, for in some cases lignites have been transformed into apparently bituminous coals, or even, by metamorphic action, into anthracitic varieties. 8 In many instances fossil charcoals have been observed, resembling ordinary charcoal; and these owe their peculiarities, perhaps, to forest fires, produced either by lightning or by eruptions of igneous rocks. 8 1 Liebig’s Annalen, vol. 157, 1871, p. 240. See also Mulder, idem, vol. 32, 1839, p. 305. 2 On fichtelite, see T. E. Clark, Liebig’s Annalen, vol. 103, 1857, p. 236; C. Hell, Ber. Deutsch. chem. Gesell., vol. 22, 1889, p. 498; E. Bamberger, idem, p. 635, and L. Spiegel, idem, p. 3369. Also M. Schuster, Min. pet. Mitt., vol 7, 1885, p. 88. 3 Reduced to simpler, comparable terms, these formulae become respectively, C 15 H 27 and C 15 H 25 . The difference is slight. 4 See G. H. Ashley, Econ. Geology, vol. 2, 1907, p. 34. 8 Acadian geology, 2d ed., p. 68. 6 See T. H. MacBride, Proc. Iowa Acad., vol. 4, 1897, p. 63; and T. E. Savage, idem, vol. 11, 1903, p. 103. 7 On American peats, see H. Ries, Fifty-fifth Ann. Rept. New York State Mus., 1903, p. r55; A. L. Parsons, idem, Fifty-seventh Ann. Rept., vol. 1, 1905, p. 16. Parsons cites many analyses. In Ann. Rept. State Geologist New Jersey, 1905, p. 223, W. E. McCourt and C. W. Parmelee describe peat deposits and give a bibliography of the subject. See also R. Chalmers, Min. Res. Canada, 1904, Bull, on Peat, for Canadian data. A partial bibliography of peat is given by J. A. Holmes in Bull. U. S. Geol. Survey No. 290, 1906, pp. 11-15. 3 These transformations have been doubted by Donath, whose work is cited later. 8 See, for example, A. Daubrde, Compt. Rend., vol. 19, 1844, p. 126, on “mineral charcoal” from the Saarbriicken coal field. 746 THE DATA OP GEOCHEMISTRY. Among the lignites several distinct varieties exist, which have received characteristic names, as follows : 1. True or xyloid lignite. This is essentially fossil wood in which the ligneous structure is more or less perfectly preserved. 2. Earthy brown coal. This variety is earthy in structure, as its name indicates, and it is often accompanied by mineral resins or fossil hydrocarbons. 3. Common brown coal. The common, compact form of lignite, and the one best known as a fuel. 4. Pitch coal, a compact variety, so named for its peculiar luster. 5. Glance coal. A hard and very compact form of lignite, most nearly resembling the Carboniferous coals. 6. Jet. A very hard variety, probably derived from the fossilization of coniferous wood. 1 Used for j ewelry and other ornamental purposes. As might be supposed, the lignites exhibit a wide range of variation in their composition. The following analyses, selected from a table in Percy’s Metallurgy, 2 show this fact clearly. They have been recal- culated upon an ash-free, water-free basis. Analyses of foreign lignites. A. From Teuditz, Germany. Analysis by Wagner. B. From Sardinia. Analyst not named. C. From Schonfeld, Bohemia. Analysis by Nendtwich. D. From European Turkey. Analyzed by W. J. Ward in Percy’s laboratory. E. From Sardinia. Analyzed by C. Tookey, in Percy’s laboratory. A B c D E c 57. 02 63. 71 69. 82 75. 08 82. 26 H 5. 94 5. 05 5. 90 5.44 6. 52 O+N 37.04 31. 24 24. 28 19. 48 11.22 100.00 100. 00 100. 00 100. 00 100. 00 For technical purposes coal analyses are commonly reported in a different form. Moisture and ash are important factors to consider, and so, too, is the distinction between the “volatile matter” and the “fixed carbon.” In lignites the moisture is usually very high, for these coals are peculiarly hygroscopic. Like other coals, they also contain sulphur, which is partly organic, partly present as inclosures of pyrite or marcasite, and partly in the form of sulphates, such as gypsum. 3 The following analyses from the reports of the fuel-test- ing plant of the United States Geological Survey 4 are fair examples of the technical mode of statement. All samples were air dried. 1 See P. E. Spielmann, Chem. News, vol. 94, 1906, p. 281; vol. 97, 1908, p. 181. For an analysis of Spanish jet see J. B. Boussingaulf, Annales chim. phys., 5th ser., vol. 29, 1883, p. 382. The latter memoir contains many other analyses of fossil combustibles. 2 1875 edition, Vol. 1, pp. 312-313. From a table of 41 analyses. 8 The resinoid substances which have been named quisqueite, tasmanite, and trinkerite are rich in organic sulphur compounds of undetermined character. See Dana, System of mineralogy, 6th ecL, p. 1010. 4 Prof. Paper No. 48, pt. 1, and Bull. No. 290, 1906. Analyses made under the direction of E. E. Sommer- meier. COAL. 747 Analyses of American lignites. A. Brown lignite, Williston, North Dakota. B. Lignite from Texas. C. Lignite from Tesla mine, Alameda County, California. D. Lignite from Wyoming. E. Black lignite from Red Lodge, Montana. A coal of doubtful character. Not certainly lignite. A B C D E Moisture 16. 70 22. 48 18. 51 17. 69 9. 05 Volatile matter 37. 10 31. 36 35. 33 37. 96 36. 70 Fixed carbon 39.49 26. 73 30. 67 39. 56 43. 03 Ash 6. 71 19.43 15. 49 4. 79 11.22 Sulphur 100. 00 .63 100. 00 .56 100. 00 3. 05 100. 00 .63 100. 00 1. 76 The elementary analyses of these coals, when ash, moisture, and sulphur are thrown out, show less variation. Elementary analyses of American lignites. A B C D E C 72. 62 73. 63 75. 19 75. 97 77. 47 H 4. 93 5. 07 6. 18 5. 36 5. 44 N 1. 20 1.35 1.04 1.41 1. 75 O... 21. 25 19. 95 17. 59 17. 26 15. 34 100. 00 100. 00 100. 00 100. 00 100. 00 For further comparison of the lignites with other fossil fuels, the subjoined averages will be useful. The data are reduced to an ash- free and water-free standard. Average analyses of lignites. A. Average of 22 Texas lignites, analyzed by Magnenat and Wooten. Dried at 105°. From E. T. Dumble’s Report on the brown coal and lignite of Texas: Geol. Survey Texas, 1892, p. 213. This volume contains many technical analyses of lignites, and also tables of analyses of German, Austrian, and Italian brown coals. B. Average of 10 analyses from the report of the fuel-testing plant of the United States Geol. Survey, already cited. C. Average of 29 lignites from various parts of the world. Analyses by C. Tookey and W. J. Ward in Percy’s laboratory. Percy’s Metallurgy, vol. 1, pp. 312-321. A B C 69. 82 74. 86 74. 17 4. 72 5. 32 5. 67 | 25. 46 18. 51 1.31 } 20.16 100. 00 100. 00 100. 00 748 THE DATA OF GEOCHEMISTRY. Data of this kind might he almost indefinitely multiplied. 1 The resinoids and fossil hydrocarbons are especially abundant in brown coals, both as visible masses and in a disseminated condition. Organic solvents, such as benzene, will extract matter of this kind from lignite, but the substances thus obtained are not of definite com- position. In some cases oily fluids exude from brown coal, 2 although instances of this kind are probably rare. Solid bodies are the rule. An extreme example of extractive matter in coal is that reported by Watson Smith, 3 who, in a Japanese lignite, found 9.5 per cent of sub- stance soluble in benzene. In their behavior toward reagents the lignites are more akin to peat than to the Carboniferous coals. Like peat, they contain humic compounds which are soluble in solutions of caustic alkalies. Accord- ing to E. Fremy, 4 peat yields abundant “ulmic acid” to alkaline solvents, xyloid lignite yields less, and compact lignite little or none at all. The bituminous coals and anthracite are insoluble in alkaline solutions. Occasionally these humic bodies are found in remarkable concentrations. The “ paper coals” of Russia, for example, con- tain layers of humic matter, which is soluble in ammonia. 5 In the brown coal of Falkenau, Bohemia, C. von John 6 found a native humus, soluble in ammonia or sodium carbonate solution, which had approximately the composition C 46 H 46 0 25 . Von John cites other examples reported by other observers. Furthermore, the pigment known as Cassel brown is a fossil humus from the Tertiary near Cassel, Germany. 7 Fremy found that lignite was also soluble in alkaline 'hypochlorites, while the true coals were not. It was also strongly attacked by nitric acid, with conversion into a yellow resinous body, soluble in an excess of the reagent or in solutions of the alkalies. Bituminous coal and anthracite, on the other hand, were feebly attacked, anthracite in particular with extreme slowness. These coals, however, dis- solved in mixtures of nitric and sulphuric acids, yielding solutions from which water precipitated a humus compound. Woody tissue, heated during several days to 200°, became comparable with lignite in its behavior toward reagents. 1 See the great monograph by C. Zincken, Die Physiographic der Braunkohle, Hannover, 1867; and its Erganzung, published at Halle in 1871. In Grove and Thorpe’s Chemical technology, vol. 1, many analyses are given; and others are cited in F. Fischer’s Chemische Technologie der Brennstoffe, Braunschweig, 1897, vol. 1. E. F. Burchard, in Proc. Sioux City (Iowa) Acad., vol. 1, 1904, p. 174, has reported data for some Nebraska lignites. 2 See A. A. Hall, Jour. Soc. Chem. Ind., vol. 26, 1907, p. 1223; J. B. Cohen and C. P. Finn, idem, vol. 31, 1915, p. 12; P. P. Bedson, idem, vol. 26, 1907, p. 1224. White and Thiessen (The origin of coal, p. 274) regard the oils in coal as derived from spore exines and pollen grains. 8 Jour. Soc. Chem. Ind., vol. 10, p. 975, 1891. * Compt. Rend., vol. 52, 1861, p. 114. 6 See R. Zeiller, Bull. Soc. g6ol. France, 3d ser., vol. 12, 1884, p. 680. 8 Verhandl. K.-k. geol. Reichsanstalt, p. 64, 1891. 7 See a recent des 9 ription by P. Malkomesius and R. Albert, Jour, prakt. Chemie, 2d ser., vol. 70, 1904, p. 509. COAL. 749 Since Fremy’s time the action of nitric acid and other oxidizing agents upon coal has been studied by various investigators. E. Gui- gnet, 1 for example, found that nitric acid acted upon coal with the formation of products more or less analogous to the nitrocelluloses, and similar observations were recorded by R. J. Friswell. 2 A com- mittee of the British Association 3 also conducted some experiments upon the proximate constitution of coals. They not only studied the action of solvents to some extent but also examined the action of hydrochloric acid and potassium chlorate upon coal. That powerful oxidizing mixture produced compounds which resembled the chlo- rinated derivatives of jute fiber. The work of the committee seems never to have been pushed to completion. The researches thus briefly summarized, it will be observed, relate partly to lignite and partly to other coals. They suggest relations between the coals and vegetable fiber, but for several reasons they are inconclusive. The records are often inexplicit, and the experi- ments are not all strictly comparable. When nitric acid, for example, is employed as a test reagent, it should be under commensurable con- ditions, such as uniform fineness of subdivision on the part of the coal and equality of concentration on the side of the acid. Time and temperature also must be taken into account. A hot, strong acid, applied to a finely powdered coal, would act differently from a cold, weak acid on coarser material. To neglect of details like these some of the discordances in the records are probably due. In recent years E. Donath and his associates 4 have studied one phase of the nitric acid reaction with much care. Dilute nitric acid, one part to nine of water, at a temperature of 70°, will attack lignite vigorously, but is without action upon bituminous coal. Even a brown-coal “anthracite,” a product of contact metamorphism by an intrusion of phonolite, behaved like ordinary lignite toward nitric acid. From evidence of this kind Donath concludes that lignite and true coal are chemically unlike and of dissimilar origin. They behave differently toward reagents, and yield different products upon destructive distillation. Neither by time, according to Donath, nor by heat, can lignite be transformed into coal. Lignite, he thinks, is derived from materials rich in lignocellulose, as shown by the pres- ence of humic compounds in it. The true coals, on the other hand, were formed from substances which were either free from woody 1 Compt. Rend., vol. 88, 1879, p. 590. 2 Proc. Chem. Soc., vol. 8, 1892, p. 9. W. C. Anderson and J. Roberts (Jour. Soc. Chem. Ind., vol. 17, 1898, p. 1013) have aiso studied the action of nitric acid on coal and made several analyses of the “coai acids” so obtained. » Ann. Rept. Brit. Assoc., 1894, p. 246; idem, 1896, p. 340. * Donath, Chem. Zeitung, 1905, p. 1027, and Zeitschr. anorg. Chemie, 1906, p. 657. Donath and H. Ditz, Oesterr. Zeitschr. Berg- u. Hiittenw., vol. 51, 1903, p. 310. Donath and F. Braunlich, Chem. Zeitung, 1904, pp. 180, 953. 750 THE DATA OF GEOCHEMISTRY. fiber, or nearly so. In the formation of bituminous coal, which is often rich in nitrogen, the proteids of animal matter probably took part. It would be premature, I think, to accept Donath’s conclusions throughout, but his evidence, taken together with that of earlier investigators, shows distinct chemical differences between the lignites and the coals. In lignites the humic compounds are readily detected, but in coal they are less apparent. Nitric acid acts easily on lignite, but with much less vigor upon bituminous coal or anthracite. How far the latter substances are derivable from the former, however, is a separate question. BITUMINOUS COAL. In composition, at least empirically, the bituminous coals lie between the lignites and anthracite. To some extent they overlap the lignites, so that it is not always easy to say where one group ends and the other begins. The following analyses of bituminous coals, all of Carboniferous age, are taken from the reports of the fuel- testing plant of the United States Geological Survey. They are selected in order to show something of the recognized variations . 1 First, there are the conventional proximate analyses: Proximate analyses of bituminous coals. A. Ehrenfeld, Pennsylvania. Bull. No. 290, p. 179. B. Bruce, Pennsylvania. Idem, p. 184. C. Vigo County, Indiana. Idem, p. 109. D. Altoona, Iowa. Prof. Paper No. 48, p. 223. E. Shawnee, Ohio. Bull. No. 290, p. 145. F. Staunton, Illinois. Idem, p. 63. A B C D E F Moisture 3. 51 2. 61 9. 55 4. 52 9. 90 13. 72 Volatile matter 16. 82 34. 92 36. 19 40. 96 33. 66 36. 24 Fixed carbon 73. 04 56. 30 43. 65 38. 99 44. 86 39. 72 Ash 6. 63 6. 17 10. 61 15. 53 11. 58 10. 32 Sulphur 100. 00 .94 100. 00 1. 26 100. 00 3. 72 100. 00 6. 83 100. 00 1. 81 100.00 3. 96 With one exception the volatilizable part of these coals is less in amount than the fixed carbon. With the lignites the reverse state- ment is generally true. The ultimate analyses of the same coals, recalculated to a water, ash, and sulphur free basis, are as follows: Ultimate analyses of bituminous coals. A B c D E F C 90. 78 85. 73 84. 19 82. 92 82. 20 81. 87 H 4. 69 5. 49 5. 82 6. 06 5. 45 5. 85 N 1. 40 1. 75 1. 42 1. 27 1. 60 1. 36 O 3. 13 7. 03 8. 57 9. 75 10. 75 10. 92 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 i The high moisture of these coals is due to the fact that the samples were sealed up immediately after collection in the mines and were not dried. Many analyses of American coals are given in Bull. U. S. Bur. Mines No. 22, 1913, by N. W. Lord. See also Bull. 85, 1914, for many other analyses. COAL. 751 The reciprocal variation of carbon and oxygen, the latter rising as the former falls, is here very well shown. Even in a single mine the composition of the coal may vary within fairly wide limits. For example, F. Fischer 1 gives 24 comparable analyses of coal from the Unser Fritz mine, district of Arnsberg, Westphalia. From the table, in which the analyses are reduced to an ash and sulphur free standard, I select the following examples, which show the maximum and minimum proportion of each con- stituent. In the last column I give the average of the entire series: Analyses of coal from Unser Fritz mine. c 85. 33 85. 06 84. 28 82. 34 80. 69 83. 81 H 5. 20 4. 66 4. 85 4. 94 4. 94 4. 98 N 1. 49 1. 35 1. 87 1. 18 1. 29 1. 47 O 7. 98 8. 93 9. 00 11. 54 13. 08 9. 74 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Other variations, due to the peculiar character of certain coaly material, are illustrated by the following analyses : Analyses of fossil plants and cannel coal. A. Average of six analyses of fossil plants, from the coal beds of Commentry, France, by S. Meunier, in Fremy’s Encyclopedic chimique, vol. 2 (Complement, pt. 1), p. 152. The plants were perfectly preserved as to structure, but entirely transformed into coal. The genera Calamodendron, Cordaites, Lepidodendron, Psaronius, Ptychopteris, and Megaphyton are represented in this average. The variations between themare small. B. Analysis of Wigan cannel, by F. Vaux, Jour. Chem. Soc., vol. 1, 1840, p. 320. C. Analysis of Tyneside cannel, by H. Taylor, Edinburgh New Philos. Jour., vol. 50, 1851, p. 145. All three analyses are here recalculated to the ash-free basis. A B c C 82. 45 83. 58 87. 89 H 4. 75 5. 77 6. 53 N .43 2. 21 2. 08 0 12. 37 8. 44 3. 50 100. 00 100. 00 100. 00 The suggestive feature of the foregoing trio is in the proportion of nitrogen. The fossil plants contain very little nitrogen; the cannels are abnormally high. The inference is that plant remains have con- tributed but a small part of the nitrogen contained in coal, and that the main supply has come from other sources. The most obvious source is animal matter, and this was probably the source of the nitro- gen in cannel. Newberry 2 long ago pointed out that fish remains 1 Zeitschr. angew. Chemie, 1894, p. 605. See also his Chemische Technologie der Brennstoffe, vol. 1, pp. 518-520. 2 Am. Jour. Sci., 2d ser., vol. 23, 1854, p. 212. J. Rofe (Geol. Mag., 1866, p. 208) has also called attention to the fish remains in Lancashire cannel. B. Renault (Bull. Soc. ind. min., 3d ser., vol. 14, p. 138) regards cannel as formed from the spores of cryptogams. No algae are found in it, or very few. See also E. C. Jeffrey, Proc. Am. Acad. Arts and Sci., vol. 46, 1910, p. 273. 752 THE DATA OF GEOCHEMISTRY. are abundant in cannel coal, and he argues that the beds were laid down under water. Vegetable matter formed a carbonaceous paste, in which the fish remains became embedded and which consolidated to produce cannel coal. For comparison with other varieties of coal, the subjoined averages will be useful. Moisture, sulphur, and ash are excluded from the table, except when otherwise specified. Average analyses of bituminous coal. A. Average of 20 analyses of bituminous coals from Pennsylvania, Maryland, Virginia, and West Vir- ginia. Combined from data given in the reports of the fuel-testing plant of the United States Geological Survey. B. Average of 40 analyses of bituminous coals from Ohio, Indiana, Illinois, Iowa, and Missouri. Also from the above-named reports. C. Average of 15 analyses of Scotch coals, by W. D. Anderson and J. Roberts, Jour. Soc. Chem. Ind., vol. 17, 1898, p. 1013. Sulphur is included in the figure for oxygen. D. Average of 18 coals from Newcastle, 28 from Lancashire, and 7 from Derbyshire, England. Recalcu- ated from averages cited by Fischer, in Chemische Technologie der Brennstoffe, vol. 1, p. 512. A B c D c 87. 52 82. 91 83. 65 84. 19 H 5. 20 5. 70 5. 48 5. 58 N 1. 61 1. 49 1. 86 1. 41 0 5. 67 9. 90 9. 01 8. 82 100. 00 100. 00 100. 00 100. 00 The peculiar chemical differences between the bituminous coals and lignite were described in the preceding section of this chapter. Many coals, which are apparently bituminous, and in fact are bitu- minous so far as technical uses are concerned, are really lignitic; at least so far as can be judged from their origin. Their true character must be determined by researches like those of Fremy and Donath, but refined methods of investigation are yet to be devised. ANTHRACITE. In anthracite the transformation of vegetable matter into carbon approaches its limit. On one side of this class of coals we find the variety known as semianthracite; on the other they approximate to graphite. The technical analyses of anthracite show a large pro- portion of fixed carbon, with relatively little volatilizable matter — a relation which appears in the following table. COAL. 753 Proximate analyses of anthracite. A. Semianthracite, Coal Hill, Arkansas. From report of the coal-testing plant, Prof. Paper U. S. Geol. Survey No. 48, 1906, p. 202. B. Anthracite culm, Scranton, Pennsylvania. Idem r p. 245. C. Lykens Valley, Pennsylvania. D. Schuylkill coal, Pennsylvania. E. Cameron coal, Pennsylvania. Analyses C, D, and E by A. S. McCreath, Rept. Second Geol. Survey, Pennsylvania, vol. MM. This volume contains many other proximate analyses of coals. See also C. A. Ashburner, Trans. Am. Inst. Min. Eng., vol. 14, 1875-76, p. 706, for a tabulated classification of Pennsyl- vania anthracites. A large number of proximate analyses are there cited. For analyses of Colorado anthracites, see W. P. Headden, Proc. Colorado Sci. Soc., vol. 8, 1907, p. 257. A B C D E Moisture 1. 28 2. 08 2. 27 2. 98 1. 82 Volatile 12. 82 7.27 8. 83 3. 38 6. 18 Fixed carbon 73. 69 74. 32 78. 83 87. 13 86. 75 Sulphur .68 .66 .75 Ash 12. 21 16.33 9. 39 5. 85 4. 50 100. 00 100. 00 100. 00 100. 00 100. 00 Ultimate analyses of anthracites are much less numerous than for the other varieties of coal. The subjoined table, however, is enough for present purposes. Ash, sulphur, and moisture are excluded. Ultimate analyses of anthracite. A. Semianthracite, Arkansas; the same as A in the preceding table. B. Welsh anthracite, analysis by F. Vaux, Join- Chem. Soc., vol. 1, 1848, p. 324. C. From Scranton, Pennsylvania. Coal B of the preceding table. D. From Mauch Chunk, Pennsylvania. Analysis by J. Percy, Quart. Jour. Geol. Soc., vol. 1, 1845, p. 204. E. From Province of Hunan, China. Analysis by F. Haeussermann and W. Naschold, Zeitschr. angew. Chemie, 1894, p. 263. This paper contains twenty-eight analyses of Chinese coals, most of them anthracitic. F. From the Bajewka, Ural. Analysis by Alexejeff, cited by Bertelsmann in an important memoir upon the nitrogen of coal, in Ahren’s Sammlung chemischer und chemisch-technischer Vortrage, vol. 9, p. 339. A valuable table of coal analyses is there given. G. Average of sixteen analyses of anthracite, compiled from various sources. A B C D E F G c 91.47 92. 73 93. 90 94. 63 94. 68 97. 46 93. 50 H 4. 25 3.37 3.22 2. 73 2. 29 .61 2. 81 N 1. 64 .85 1. 00 1. 36 .76 .35 .97 O 2. 64 3. 05 1. 88 1. 28 2. 27 1. 58 2. 72 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 Anthracite, however, is not the extreme end of the coal series. There are pre-Carboniferous coals, which are found only in small quantities, and which approach still more closely to pure carbon. The following substances belong in this class, with the possible excep- tion of the first example. The crude analyses are given first. 97270°— Bull. 616—16 48 754 THE DATA OF GEOCHEMISTRY. Analyses of anthraxolite, schungite , and graphitoid. A. Anthraxolite, near Kingston, Canada. Analysis by W. H. Ellis, Chem. News, vol. 76, 1897, p. 186. Found in Lower Silurian limestone. B. Anthraxolite, near Sudbury, Canada. Analysis by Ellis, loc. cit. Found in the Cambrian. Ellis gives partial analyses of anthraxolites from three other localities. See also A. P. Coleman, Sixth Ann. Rept. Ontario Bur. Mines, 1897. C. Schungite, from Schunga, near Lake Onega, Russia. Mean of six analyses, reduced to anhydrous form, by A. Inostranzeff, Neues Jahrb., 1880, Band 1, p. 97; see also the same journal for 1886, Band 1, p. 92. Found in the Huronian. D. Graphitoid, from the mica schist and phyllite of the Erzgebirge. Analysis by A . Sauer, Zeitschr. Deutsch. geol. Gesell., vol. 37, 1885, p. 441. A B c D c 90. 25 94. 92 98. 11 24. 855 H 4. 16 .52 .43 .06 N .52 1. 04 .43 S . 66 . 31 0 3. 69 1. 69 h 2 o 1. 01 Ash .72 1. 52 1. 09 73. 854 100. 00 100. 00 100. 06 99. 779 Rejecting ash, water, and sulphur, these analyses assume the fol- lowing form, comparable with the analyses of other coaly substances: Recalculated analyses of anthraxolite, schungite, and graphitoid. ‘ A B c D C 91. 53 4. 22 .53 3. 72 96. 69 .53 1. 05 1. 73 99. 12 .44 .44 99. 76 .24 H N 0 100. 00 100. 00 100. 00 100. 00 These minerals, and many anthracites also, might be properly described as metamorphic coals. They cannot, however, even in the extreme cases, be termed graphitic, for they consist mainly of amor- phous carbon. Graphite is a crystalline mineral, and upon treat- ment with powerful oxidizing agents it can be transformed into a substance known as graphitic acid, 1 C n H 4 0 5 . The amorphous car- bons do not yield this derivative, and Inostranzeff failed to obtain it from schungite. The approach to graphite, therefore, is empirical only, and not constitutional — a conclusion which needs to be checked by a study of many other so-called ‘‘graphitic coals.’ ’ That term may be applicable in some cases, but they are yet to be established. i See B. C. Brodie, Liebig’s Annalen, vol. 114, 1860, p. 6. COAL. 755 THE VARIATIONS OF COAL. For comparison of all the fuels, starting with wood and ending with anthracite, the subjoined table has been compiled from the data given in the preceding pages. In the case of wood the figure for nitrogen is the mean of the determinations by Chevandier, Gott- lieb, and Hawes. Average composition of fuels. C H N 0 Wood 49. 65 6. 23 0. 92 43. 20 Peat 55. 44 6. 28 1. 72 35. 56 Lignite 72. 95 5. 24 1. 31 20. 50 Bituminous coal 84. 24 5. 55 1. 52 8. 69 Anthracite 93. 50 2. 81 .97 2. 72 This table may be restated in a different form, so as to show the proportion of the other elements to 100 parts of carbon. It then appears as follows: Comparative proportions of constituents of fuels. C H N 0 Wood 100 12.5 1. 8 87. 0 Peat 100 11. 3 3. 1 64. 1 Lignite 100 7. 2 1.8 28. 1 Bituminous coal 100 6. 6 1.8 10. 3 Anthracite 100 3.0 1.3 2.9 A steady decrease in hydrogen and oxygen thus becomes apparent. The data for nitrogen, however, are less conclusive, because of the uncertainty in the analyses of wood. If Hawes’s average for the acrogen plants, 1.59 per cent of nitrogen, be taken, then its ratio becomes 3.1, identical with the figure for peat, and a definite decrease follows. New analyses of wood, with reference especially to its nitrogen content, are much to be desired. A closer scrutiny of the foregoing table reveals still another fact, namely, that the proportional decrease in oxygen is greater than in the case of hydrogen. In cellulose, C 6 H 10 O 5 , these two elements exist in exactly the proportions required to form water. In wood the hydrogen is slightly in excess of that ratio (1:8), and the excess steadily increases until, in anthracite, it is proportionally very large. In wood the ratio is nearly 1:7; in anthracite, roughly, 1:1. This progressive variation in the ultimate composition of the coals implies a corresponding variation in their proximate character, a class of changes to which attention has already been called. Even 756 THE DATA OF GEOCHEMISTRY. the crudest analyses are conclusive in regard to one form of varia- tion. Peat, ignited in a covered crucible, yields much volatile matter and relatively little fixed carbon. In lignite the fixed carbon is higher, but commonly less than the volatile products. Bituminous coal is progressively richer in fixed carbon, while in anthracite the volatile portion has become exceedingly small. This particular variability is so characteristic that the ratio between fixed carbon and volatile matter has been adopted by some authorities as a basis for the classification of coals. 1 Such a method of classification has the merit of convenience, for it requires only proximate analyses, which are numerous and easily made, although it must be admitted that their accuracy is often questionable. Moreover, the nature of the volatile matter varies in different kinds of coal, a part of it being combustible, and a part consisting of water and other noncom- bustible products formed during the process of burning. In fact, the volatile matter is exceedingly complex, as is shown by a study of the substances formed when coal is distilled for the production of illuminating gas. The gas itself may contain hydrocarbons, free hydrogen, both oxides of carbon, nitrogen, and compounds of sul- phur. Ammoniacal water solutions are also produced, together with coal tar; and in the latter a number of complex hydrocarbons are found, and also oxidized bodies such as phenol. In 20 analyses of coal gas, P. F. Frankland 2 found the following range of variations in the percentages of the principal constituents: Variations in composition of coal gas. C0 2 0 to 2.73 0 2 0 to 1.00 N 2 - 2.07 to 10.84 H 2 33.24 to 53.79 CO 2.46 to 7.14 CH 4 36.55 to 42.93 The other products of distillation, obviously, must have been equally variable. The destructive distillation of wood yields sub- stances quite unlike those derived from coal; methyl alcohol, acetone, and acetic acid being conspicuous among them. 3 On account of this distinction between the combustible and non- combustible portions of the distillates from coal, S. W. Parr 4 has proposed a technical classification of these fuels which differs essen- tially from the system above mentioned. His scheme is based upon the ratio between the total carbon and the carbon of the volatile matter, which latter is largely but not wholly combustible. He also 1 See, for example, P. Frazer, Trans. Am. Inst. Min. Eng., vol. 6, 1877-78, p. 430, and C. A. Ashbumer, idem, vol. 14, 1885-86, p. 706. 2 Jour. Soc. Chem. Ind., vol. 3, 1884, p. 273. 3 A good article on the distillation of wood is in Watts’s Dictionary of applied chemistry, vol. 3, 1893, p. 1026. The subject can not be discussed at length here. * Bull. No. 3, Illinois Geol. Survey, 1906. Also Jour, Am. Chem. Soc., vol. 28, 1906, p. 1425. COAL. 757 takes into account the percentage of “ inert volatile” matter, which seems to vary in a manner characteristic of the different groups of coals. M. R. Campbell/ on the other hand, has argued in favor of the ratio C : H, with which he has classified the analyses made at the fuel-testing plant. These classifications are chiefly of technological significance, and their discussion falls outside the range of this work. The most important variations in coal, however, are those which were outlined under lignite. Passing from peat to anthracite there* is a progressive diminution in the proportion of humus substances and also in the solubility of the coals in various reagents. The necessary details to illustrate these variations have already been given and need no further repetition here. THE GASES IN COAL. Both peat and coal, the latter in all its varieties, contain occluded or enclosed gases, often in large amount. In coal mines they some- times escape in formidable volume, forming the so-called choke damp and fire damp of mining parlance. The choke damp consists of carbon dioxide or nitrogen or both together; the fire damp is prin- cipally methane. The development of these gases can be traced back to the earliest stages of coal formation, when marsh gas was produced, along with carbon dioxide, in the process of vegetable decay. The evolution of methane from swamps was mentioned in the preceding chapter, with reference to its existence in petroleum and as natural gas. Its ema- nation from peat is another example of the same phenomenon, and is mentioned now for the reason that it was quantitatively studied by Websky. 1 2 In a single analysis of gas* extracted from peat he obtained the following percentages: C0 2 2. 97 CH 4 43.36 N 2 53.67 100. 00 The nitrogen from this gas is presumably a residue from the ground air, the oxygen of the latter having been consumed, partly to form carbon dioxide and partly water. The gases occluded by lignite, so far as our information now goes, are of quite a different character. As analyzed by J. W. Thomas, 3 who obtained his material by heating lignite in vacuo to 50°, 100°, and 200°, successively, they consist principally of carbon dioxide, with 1 Prof. Paper U. S. Geol. Survey No. 48, 1906, pp. 156-173. See also P. Frazer, Bull. Am. Inst. Min. Eng., March, 1906; L. P. Breckenridge, Bull. U. S. Geol. Survey No. 325, 1907, p. 68. 2 Jour, prakt. Chemie, vol. 92, 1864, p. 76. 3 Jour. Chem. Soc., vol. 32, 1877, p. 146. See also Zitowitsch, Jour, prakt. Chemie, 2d ser., vol. 6, 1873, p. 79, on gases from Bohemian lignites. 758 THE DATA OF GEOCHEMISTRY. subordinate carbon monoxide and nitrogen, and insignificant propor- tions of oxygen and hydrocarbons. The following examples are suffi- cient to show the general nature of his analyses: Analyses of gases from lignite. A. Gas from Bohemian lignite, extracted at 100°. B. Gas from Bovey Heathfield lignite at 50°; 100 grams of coal gave 56.1 cubic centimeters of gas. C. Gas from the same coal at 100°, 59.9 cubic centimeters. D. Steam coal. 147.4 cubic centimeters gas. E. Gas evolved from sample D on heating to 200°. A B C D E COo 96. 41 1. 20 87. 25 3. 59 89. 53 5. 11 96.05 3. 20 86. 30 7.41 3. 34 2. 08 .53 CO ch 4 Olefines Traces. .33 C,H S o 0 2 .32 2. 17 .24 8. 92 .33 5. 03 No .42 .34 al00. 10 100. 00 100. 00 100. 00 100. 00 a The error in summation is probably due to an unidentifiable misprint in the original. Marsh gas, it will be seen, only appears in the product of heating lignite to 200° after decomposition had begun. In these lignites, at least, marsh gas is not normally occluded, but it would be rash to say that all other lignites follow the same rule. It is desirable that many more lignites should be examined in order to see whether or not they exhibit the same peculiarity. The samples studied by Thomas may possibly be exceptional. In another investigation Thomas 1 examined the gases extracted in vacuo at 100° from camrel coal and jet. The analyses are subjoined, with a statement of the volume of gas yielded by 100 grams of each sample. Analyses of gases from cannel coal and jet. A. Wigan cannel. 421.3 cubic centimeters gas. B. Wigan cannel. 350.6 cubic centimeters gas. C. Scotch cannel, Wilson town. 16.8 cubic centimeters gas. T>. Scotch cannel, Lesmahago. 55.7 cubic centimeters gas. E. Cannel shale, Lasswade, near Edinburgh. 55.7 cubic centimeters gas. F. Whitby jet. 30.2 cubic centimeters gas. A B c D E F co 2 6. 44 9. 05 53. 94 84. 55 68. 75 10. 93 CEL.. 80. 69 77. 19 VAA 4 ## 4. 75 7. 80 2. 67 v 2 AJ -6* CoHa. . .91 V 3 XA 8* * 86. 90 No 8. 12 5. 96 46. 06 14. 54 28. 58 2. 17 100. 00 100. 00 100.00 100. 00 100.00 100.00 i Jour. Chem. Soc., vol. 30, 1876, p. 144. COAL. 759 The variations here are most remarkable. Methane predominates in the gases from two cannels, carbon dioxide and nitrogen in the other three. In jet the proportion of butane is extraordinary, espe- cially for the reason that jet is essentially a fossil wood, or, in other words, a lignite. The gases occluded by bituminous coal have been studied by several chemists. E. von Meyer 1 investigated a number of German coals, and also a series from the north of England. Several coals from the Newcastle region were studied by P. P. Bedson 2 and W. McConnell. 3 For Welsh coals there are data by J. W. Thomas. 4 In Thomas’s memoir both bituminous coals and anthracite are included, and from it I select the following analyses. The gases were extracted at 100° in vacuo, and in volumes which are referred to the uniform standard of 100 grams of coal. Analyses of gases from bituminous and anthracite coal. A. Bituminous coal. 55.9 cubic centimeters gas. B. Bituminous coal. 39.7 cubic centimeters gas. C. Bituminous coal. 55.1 cubic centimeters gas. D. Steam coal. 147.4 cubic centimeters gas. E. Steam coal. 194.8 cubic centimeters gas. F. Anthracite. 600.6 cubic centimeters gas. G. Anthracite. 555.5 cubic centimeters gas. A B C D E F G co 2 36. 42 9. 43 5. 44 18. 90 5. 04 14. 72 2. 62 ch 4 31. 98 63. 76 67. 47 87. 30 84. 18 93. 13 Oo .80 2.25 1.05 1.02 .33 N 2 62. 78 56. 34 29. 75 12. 61 7. 33 1. 10 4. 25 100. 00 100. 00 100. 00 100. 00 100. 00 100. 00 100.00 The gases obtained by Yon Meyer from Saxon and Westphalian coals were similarly variable in composition. In some of them ethane was reported up to 23 per cent; and also hydrocarbons, in small amount, of undetermined character. By weight the gases form only a fraction, usually a small fraction of 1 per cent of any coal. The variability thus shown may easily be misinterpreted. The coals emit gases even in the mines, and the laboratory samples, there- fore, do not represent the true character of the material under ground. Something is lost in transit from the mine to the laboratory, and its amount is conditional upon the texture of the coal. A hard, compact anthracite retains much of its gaseous charge; a porous coal, on the other hand, will lose much. So we see that the bituminous coals con- tain, as a rule, less gas in the laboratory than the anthracites, although 1 Jour, prakt. Chemie, 2d ser., vol. 5, 1872, pp. 144, 407; vol. 6, 1873, p. 389. Data reproduced in Percy’s Metallurgy, vol. 1, 1875, p. 283. 2 Trans. North of England Inst. Min. Mech. Eng., vol. 37, p. 245. 3 Jour. Soc. Chem. Ind., vol. 13, 1894, p. 25. * Jour. Chem. Soc., vol. 28, 1876, p. 793. 760 THE DATA OF GEOCHEMISTEY. the bituminous mines are the most seriously affected by fire damp. In the coal beds themselves the bituminous coals are richest in gaseous occlusions. McConnell, in the memoir previously cited, also points out that in the Newcastle region the older and deeper coals contain the most methane, while in the younger seams carbon dioxide may predominate even to the exclusion of combustible gases. In his investigation of the Welsh coals, Thomas analyzed 14 samples of gases emitted from crevices or “blowers” in the mines, and found that they contained from 47.37 to 97.65 per cent of methane, with over 94 per cent in all but two of them. Other earlier analyses of colliery gases have told essentially the same story. 1 Methane is the principal gas of coal beds. ARTIFICIAL, COALS. Various attempts have been made to prepare artificial coals in the hope of gaining some information upon the genesis of the natural products. Two lines of research are represented in these efforts, but neither has yet led to any final conclusions. In the first class of experiments it was sought to produce coals by pressure. W. Spring 2 subjected peat to a pressure of 6,000* atmos- pheres, and transformed it into a hard, black, brilliant solid which was outwardly undistinguishable from coal. On the other hand, R. Zeiller, 3 working with pressures of 2,000 to 6,000 kilograms to the square centimeter, found that peat and also the “ulmic acid” from the paper coals of Russia were merely compacted without change of chemical character. They retained their solubility in ammonia and showed no evidence of a true transformation into coal. Some experiments by Giimbel, 4 who subjected lignite to pressure as high as 20,000 atmospheres, showed that even under such conditions no serious changes were produced and that the vegetable structure was in great measure preserved. In the second class of experiments heat is used as the transforming agent. In the ordinary process of charcoal burning wood is heated out of free access of air, decomposition ensues, volatile matter is expelled, and a form of amorphous carbon finally remains in the kiln. Violette, 5 who has studied this process with great care, found 1 See G. Bischof, Edinburgh New Philos. Jour.,vol. 29, 1840, p. 309; vol. 30, 1840, p. 127; T. Graham, Mem. Chem. Soc., vol. 3, 1845, p. 7; Lyon Playfair, Mem. Geol. Survey Great Britain, vol. 1, 1846, p. 460. A recent paper on the gases in coal is by F. G. Trobridge, Jour. Soc. Chem. Ind., vol. 25, 1906, p. 1129. See also the analyses of explosive gases from American coals by R. T. Chamberlin, in Bull. U. S. Geol. Survey No. 383, 1909. In them methane is the important constituent. On the other hand, gases from Silesian coal analyzed by J. Meyer (Jour, prakt. chem., 2d ser., vol. 90, 1914, p. 141) contained principally carbon dioxide (choke damp), with some oxygen and nitrogen, and methane occasionally. Recent work on gases in coal by C. H. Porter and F. K. Ovitz is published in Tech. Paper U. S. Bur. Mines No. 2, 1911. 2 Bull. Acad. roy. sci. Belgique, vol. 49, 1880, p. 367. * Buil. Soc. g6ol. Frahce, 3d ser., vol. 12, 1884, p. 680. 4 Sitzungsb. Math.-phys. Classe, K. bayer. Akad. Wiss. Miinchen, vol. 13, 1883, p. 141. 6 Annales chim. phys., 3d ser., vol. 32, 1851, p. 304. COAL. 761 that when wood was heated nearly to 400° in a sealed tube, 78.5 per cent of it remained as a solid residue which had all the appearance of a fatty coal. In this case the volatile substances exerted a great pressure upon the contents of the tube, and a product very different from ordinary charcoal was formed. By heating wood under con- ditions which permitted the volatile matter to escape, he obtained a series of charcoals which varied in composition according to the temperature at which they were prepared. The experiments were conducted at temperatures ranging from 150° to the melting point of platinum; and his analyses of the products thus formed, 28 in all, show progressive changes, analogous to the changes observed in the passage from wood to anthracite. The charcoals, however, are not identical with coal, but differ from it both texturally and chemically. A finished charcoal is really the analogue of coke, being in fact the coke of wood; but in its preparation it is possible to trace, step by step, the breaking down of the original ligneous fiber. For that reason it is most desirable that the chemistry of charcoal burning should be studied much more in detail than it has been hitherto. Violette’s experiments with wood in sealed tubes were not the first of their kind. Early in the nineteenth century Sir James Hall obtained an artificial coal by heating wood in a closed cylinder of iron, and in 1850 or 1851 C. Cagniard-Latour 1 performed essentially the same experiment in tubes of glass. These earlier experiments, however, were merely qualitative, for the products obtained were not analyzed. In 1879 Fremy 2 published an interesting series of observations, based upon experiments with carbohydrates other than cellulose, and upon the so-called “ulmic acid” from two sources. One example of ulmic acid was extracted from peat; the other was prepared from a constituent of woody tissue to which Fremy gave the name vasculose. The substances were all heated in sealed glass tubes to temperatures which seem to have been near 300° and yielded residues which behaved in all respects like coal. When heated to redness, they gave off water, gas, and tar and left behind a remainder of coke. These artificial coals had the following composition : Composition of artificial coals. c H 0 Coal from sugar 66. 84 4. 78 28. 43 Coal from starch 68. 48 4. 68 26. 84 Coal from gum arabic 78. 78 5. 00 16. 22 Coal from ulmic acid, peat 76. 06 4. 99 18. 95 Coal from ulmic acid, vasculose 78. 78 5.31 18. 26 i Compt. Rend., vol. 32, 1851, p. 295. 2 idem, vol. 88, 1879, p. 1048. 762 THE DATA OF GEOCHEMISTRY. The similarity of these products to natural coals, especially in the last three examples, is evident. Still more recent experiments of this order are those of S. Stein . 1 He heated wood with water in sealed tubes, but at different tempera- tures, and partially analyzed the coaly substances thus obtained. His results are briefly as follows: Experiments to obtain coaly products from wood. Temperature. Time of heating. c H Hours. Per cent. Per cent. 245 9 64.3 5.4 250 6 69.2 5.1 255 6 70.3 5.2 265 5 72.8 4.7 275 6 74.0 4.5 280 5 77.6 4.1 290 5 81.3 3.8 Here we have a series of products ranging in composition from a substance near peat to one more closely resembling coal. Only, it must be observed, the hydrogen toward the end of the series is lower than in coals showing the same percentage of carbon. The parallel- ism between the artificial and the natural substances is therefore not quite complete. The natural inference from this conclusion is that agencies other than heat and pressure have taken part in the car- bonization of vegetable matter, and these may have been microbian in character. The function of heat is to decompose the organic com- plexes; that of pressure is to retard the change and to prevent the escape of the volatile products; the combined effect must vary with variations in the intensity of the two agencies. If an exact adjust- ment of heat and pressure could be arranged, it is possible that a true artificial coal might be prepared, but this is a mere supposition. From one point of view the experiments with sealed tubes appear to be irrelevant. The change of woody fiber to peat or lignite is initiated at low temperatures and under nearly atmospheric pressure, conditions quite unlike those which either Yiolette or Stein adopted. As the rotted material becomes buried the pressure upon it increases; but, except where igneous intrusions have operated, there is nothing to show that especially high temperatures have been at work. The element of time, however, must be considered. The natural processes are carried on slowly; and it may be that the laboratory methods merely accelerate them. So far, then, the experiments are pertinent but inconclusive. They certainly do not cover all the ground. All 1 Chem. Centralbl., 1901, pt. 2, p. 950. From a Hungarian original which I have not seen. F. Bergius (Jour. Soc. Chem. Ind., vol. 32, 1913, p. 462) heated cellulose with water under pressure of 340°, and ob- tained a product undistinguishable from coal. COAL. 763 that can be said is that moderate temperatures and pressures, oper- ating for a long time, may produce results resembling those which are brought about rapidly in the laboratory. In order to account for what we might call the anthragenetic process, various hypotheses have been framed. J. F. Hofmann , 1 for example, has used the analogy offered by the spontaneous combus- tion of grain, flax, and hay, and suggested that something of the same sort may happen in the buried materials from which coal is formed. In that phenomenon heat is generated by fermentation, and when actual inflammation is prevented for lack of air a partial carbonization may occur. In cases of this kind heat is generated locally and an imperfect combustion occurs. Hofmann’s suggestions are interesting, but, so far as the formation of coal is concerned, the evidence in their favor is very incomplete. How far micro-organisms are active in the formation of coal is doubtful. They abound in the stagnant waters of swamps, and certainly have much to do with the earlier stages of vegetable decay. They start the process, but at the same time they generate antiseptic compounds which limit their activity. Peat, not far below the sur- face, is distinctly antiseptic and inimical to microbian life. Never- theless, a number of authorities have argued strongly in favor of these organisms as principal agents in an thr agenesis. B. Renault 2 has found their remains in lignite and coal in significant abundance and variety. THE CONSTITUTION OF COAL. In the preceding pages, under other captions, I have cited a good deal of evidence relative to the substances found in coal or from which coal has been derived. Its vegetable orgin is clear and needs no further discussion now; its present constitution is more difficult to determine. The question of constitution presents itself under two aspects, the one structural the other chemical. On the one side microscopic evi- dence is available, and it is seen that coal contains vegetable remains, micro-organisms, resinoid bodies, and so on. In some coals spores or spore cells are abundant ; 3 in others, as shown by Renault, remains of 1 Zeitschr. angew. Chemie, 1902, p. 821. 2 Bull. Soc. ind. min., 3d ser., vol. 13, 1899, p. 865; vol. 14, 1900, p. 1. See also L. Lemiere, idem, 4th ser., vol. 4, 1905, pp. 851, 1248, and vol. 6, 1906, p. 273. Also in Compt. rend. VIII Cong. g6ol. intemat., 1900, p. 502. Lemi&re regards the soluble or diastatic ferments, derived from living vegetation, as also operative in the process of vegetable decay. 8 See J. W. Dawson, Am. Jour. Sci., 3d ser., vol. 1, 1871, p. 256. *E. Orton (idem, vol. 24, 1882, p. 171) states that spore cases are abundant in the “ sub-Car boniferous” rocks of Ohio, and are also found in the Devonian. On the microscopic structure of the natural hydrocarbons, resins, and coals, see Fischer and Rust, Zeitschr. Kryst. Min., vol. 7, 1882, p. 209. The important memoirs by Bertrand and Renault and by Jeffrey have already been referred to. See also White and Thiessen’s bulletin on the origin of coal, already cited, for a full summary of this subject, with many additional details. 764 THE DATA OF GEOCHEMISTRY. algae are found. The lignites are obviously derived from woody fiber, and, in short, in many cases the proximate origin of the coals is not difficult to determine. Their structure, microscopic or macroscopic, tells a pretty clear story. On the chemical side the problems are much less simple. The proximate constituents of coal are most imperfectly known and the little knowledge we have is mainly qualitative. The necessary investigations are difficult, the methods are not well formulated, and the available data are scattered and fragmentary. ’To what extent free carbon exists in coals is still an open question. It is probably absent from lignite and abundant in the extreme anthracites; but its quantitative determination can not be effected by any known analytical process. There are two distinct lines of attack upon the problem in ques- tion. First, by means of solvents, to extract certain constituents of coal and to identify them. Some of these constituents, which are commonly small in amount, can be dissolved by gasoline, ether, ben- zene, chloroform, alcohol, and other organic solvents. The extrac- tive matter thus obtained is, unfortunately, not simple, but seems to contain a mixture of substances whose nature is yet to be determ- ined. By handling large quantities of material these bodies may be obtained in sufficient abundance for more complete investigation, and their separation into definite fractions is by no means hopeless . 1 The remarkable solvent action of pyridine upon some of the con- stituents of coal, as studied in recent years by several investigators , 2 also offers a promising line of attack upon the problems. Alkaline solvents, such as caustic soda, caustic potash, and ammo- nia, dissolve, as we have already seen, humic substances from peat and brown coal, but not from the older carbons. These substances are indefinite, but in time their nature may be determined, and their correlation with the ligneous carbohydrates ought then to become possible. If, however, as is supposed, some coals are derived from gelatinous algae, the problem becomes more complex. The chemical constitution of those forms of vegetation is still very obscure. Up to the present time the mistake has been made, by chemists engaged in the study of coal, of assuming that the celluloses are the chief starting points — an assumption which is not unqualifiedly true. Car- 1 On this subject see the authorities already cited. Also P. Siepmann, Preuss. Zeitschr. Berg-, Hiitten- u. Salinenwesen, vol. 39, 1891, p. 27. F. Muck (Die Chemie der Steinkohle, Leipzig, 1891) gives a good summary of earlier investigations by Dondorff, Reinsch, etc. An interesting memoir by W. C. Anderson (Proc. Philos. Soc. Glasgow, vol. 29, 1897, p. 72) also describes a number of important experiments. 2 T. Baker, Trans. Inst. Min. Eng., vol. 20, 1900, p. 159; and P. P. Bedson, Join-. Soc. Chem. Ind., vol. 27, 1908, p. 147. See also E. Donath, Chem. Zeitung, vol. 32, 1908, p. 1271; L. Vignon, Compt. Rend., vol. 158, 1914, p. 1421; A. Wahl, idem, vol. 154, p. 1095. J. C. W . Frazer and E. G. Hoffman (Tech. Paper U. S.Bur. Mines No. 5, 1912) have studied the extracts obtained from coal with phenol. A . Pictet and L. Ramseyer (Ber. Deutsch. chem. Gesell,vol. 44, 1911, p. 2486), by extraction with hot benzene obtained hexhydro- fluorene, C13 H 16 . By solution with carbon disulphide E. Donath and O. Manouschek (Chem. Zeitung, 1908, p. 1271) extracted anthracene and chrysene from a German coking coal. coal. 765 bons of animal origin also require attention. Much preliminary work of this kind remains to be done. The direct separation of its constituents from coal is, however, possible only to a very limited extent. Hence the second line of attack, the conversion of these bodies into recognizable derivatives, is also essential. Not only do we need more experiments along the line developed by Donath, whose distinction between the lignites and the true coals has already been discussed, but much more needs to be done in the study of oxidation products, chlorine derivatives, etc. For example, in addition to the researches upon the nitrocompounds derivable from coal and the chlorination experiments reported to the British Association, there are investigations like that conducted by L. Schinnerer and T. Morawsky . 1 These chemists fused lignite with caustic soda, and by distillation of the melt obtained pyrocatechin, which is a benzene derivative. The true coals, so far as examined, did not yield this compound, which seems to have been produced from the resinoid constituents of the lignite. By experiments of this order the compounds existing in coal can be correlated with other substances of known constitution, and some at least of the problems which confront us may be solved. The future chemistry of coal will be shaped by a study of its immediate constitution and not by the multiplication of empirical analyses. 1 Ber. Deutsch. chem. Gesell., vol. 5, 1872, p. 185. INDEX. A. Page. Aar, River, analysis of water 97 Abbot, C. G., and Fowle, F. E., carbon diox- ide and climate. 48, 146 Abbot, H. L. See Humphreys and Abbott. Abert Lake, analysis of water 161, 176 Abich, H., analyses of spinel 342 Abilena well, analysis 187 Abilene artesian well, analysis 182 Absorption, of substances by soils 211, 501, 502 Acanthite 650 Acetylene 716,723,724 Acetylene series 717 Acheson, E. G., artificial graphite 326 d’ Achiardi, A . , origin of borates 245 d’Achiardi, G., minerals in marble 622,623 origin of borates 245 Ackroyd, W., atmospheric transport of salt. . 52, 149,168 relative abundance of elements 28 Acmite 379-381 Actinium 12,314 Actinolite 384 Actinolite-magnetite schist 384,610 Adamellose 453 Adamite 672 Adams, B. F., cited 45 Adams, F. D., allanite and epidote 408 alteration of pyroxene 383 amphibolite 623 analyses by 87,185 compression of granite 33 melilite rocks 400 monmouthite 446 primary calcite 418 Adams, F. D., and Harrington, B. J., has- tingsite 387 Adams, F. D., and Lawson, A. C., scapolite diorite 405,597 Adams, G. L, concentration of petroleum 736 gypsum 232,576 native sulphur 577 salt deposits 229 zinc deposits 675 Adams, L. H. See Johnston and Adams. Adirondackiase 467 Adler, River, analysis of water 98 Adobe soil 509-511 Adriatic Sea 122 Adschi-Darja. See Karaboghaz. Aegirite 378-381 Aenigmatite 388,389 Agate 357 Aguilarite 652 Aguilera, J. G.,stibnite 689 Aichino, G., bauxite 497 Page. Aigner, A., polyhalite 227 Aikinite 661,662 Air, dissolved, composition of 477 See also Atmosphere. Aisinmann, , origin of petroleum 730 Aitken, J., atmospheric dust 53 Akermanite 398 Akerose 440, 442, 445, 455, 456 Alabama River, analysis of water 74 Alaskite 434 Alaskose 435,437 Albanose 447 Albert, R. See Malkomesius and Albert. Albertite 719,720 Albite 363-368,600 Albite mosaic 594 Albrecht, R., optical activity of petroleum. . 735 Aldebaranium 21 Alexandrolite 696 Alexejeff, W., dopplerite 744 Alferric minerals 425 Algae, as limestone makers 555,565,568 as source of bitumens 733 in relation to coal 740 magnesium carbonate in 565 siliceous... i 515 Algodonite 658 Aiipite 695 Alkali, in soils 237-242 Allanite 406-408,712 Allegheny River, analysis of water 78 Allemontite 688 Allen, E. T., aluminum hydroxide 498 analyses by 232,332 native iron 331 synthesis of quartz 358 See also Day and Allen. Allen, E. T., and Clement, J. K., water in amphiboles 387 Allen, E. T., and Crenshaw, J. L., greenockite. 670 pyrite and marcasite 334 sulphides of mercury 666 sulphides of zinc 670,671 Allen, E. T., Johnston, J., and Crenshaw, J. L., sulphides of iron 334 Allen, E. T., and White, W. P., fusion of lime silicate 292,300 synthesis of diopside 379 wollastonite 378,621 Allen, E. T., Wright, F. E., and Clement, J. K., magnesium silicate 292, 377,385,390 Allen, I. C., and Burrell, G. A., natural gas . . 714 Allen, O. D., analyses by 155, 159,203,235,236,237,238 Alloclasite 692 767 768 INDEX. Page. Allopalladium 700 Allophane 415,500,611 Alma well, analysis cited 185 Almandite 400 Aloisi, P., spinel rocks 343 Altai, Lake, analysis of water 170, 174 saline deposit 234 Altaite 676 Altmuhl, River, analysis of water 101 Aluminum, distribution 13 in sea water 121 Alum shale 545 Alums 249,259,270 Alunite — 259,497 Alunogen 259 Alway, F. J., and Gortner, R. A., water anal- ysis 163 Amalgam 644 Amazon River, analyses of water 91, 107 Amber 741 Amblygonite 686 Amesite 397-398 Ammiolite 664 Ammonia, in rainfall 50 in sea water 120 A mm onium fluoride, in volcanic gases 261 Amphiboles 383-389 Amphibolite 592,623 Amsoldingen, Lac 95 Ana River, analysis of water 161 Analcite 368-371 Analcite rocks , 449-451 Anamorphism, zone of 584 Anatase 350-352 Andalusite 409, 410, 601, 612 Andalusite rocks 614 Anderlini, F. See Nasini, R. Andersen, O. See Bowen and Andersen. Anderson, , cited 168 Anderson, W., cited 160 Anderson, W. C., experiments on coal 764 Anderson, W. C., and Roberts, J., coal 749, 752 Anderson, W. S., solubility of calcium car- bonate 128 See also Irvine and Anderson. Andesine 364 Andesite 453-455,487 Andesner, H., fusion of gabbroid magma. . 306, 422 Andorite 653,678 Andose 452,455,456,458,461,462 Andouard, A., phosphate rock 521 Andradite 401 Andr6, G., cited 480 Andr6e, K., bibliography of oceanic sedimen- tation 515 fluorite in sediments 582 Andrew, A . R . , gold in country rock 642 phosphate rock 528 Andrews, E. C., magmatic assimilation 310 Andrews , T . , native iron 328 Androscoggin River, analysis of water 71 Androussof, N., reduction of sulphates by bacteria 148,515 Anemousite 364 Anger, F. A., shale 547 Angemsee , analysis of water 104 Page. Anglesite 680 Angstrom, K . J . , carbon dioxide and climate . 48 Anhydrite 223, 229, 232, 247, 249, 251, 255 Animikite 650 Ankerite 563,571 Annabergite 694 Annecy, Lake of, analysis of water 94 Anorthite 363-368 Anorthoclase 363 Anorthosite 462 Ansdell, G. See Dewar and Ansdell. Ansel, H., iron ores 575 Anthon, E . F . , precipitation of sulphides 639 Anthophyllite 383 Anthracite 752-754 Anthraxolite 754 Antimony, distribution 14 ores of 687-691 Ants, geological work of 485 d’Aoust, V., oolite 550 Apatite 354-355,519 Aphrosiderite 397 Aphthitalite 223 Apjohn, J., water of the Dead Sea 169 Aplite 434,437 Apophyllite 416,417 Aragonite 251, 417, 551, 552 Aral, Sea of, analysis of water 166, 175 Arapahite 468 Arapahose 468 Arctic Ocean, analyses of water 124 Arctowski, H., synthesis of hematite 347 Ardennite 707 Arfvedsonite 388,389 Argali, P., distribution of nickel 691 Argentite 650 Argon, distribution 14, 41 infumaroles 268 in spring waters 180 Argyrodite 653 Arias, Rio de, analysis of water 92 Arkansas Hot Springs, analysis of water 195 Arkansas River, analysis of water 66, 81 Arkansose 447 Arkite 447 Arnold, R., and Anderson, R., .alteration of shale 609 Aromatic hydrocarbons 717 Arrhenius, S. A. , carbon dioxide and climate. 47, 145 nature of earth’s interior 57 volcanic explosions 285, 286 Arsandaux, H. , analysis by 522 bauxite 496 laterite 494 Arsem, C. W., graphite 328 Arsenic, distribution 14 in sea water 120 ores of 687-691 Arsenolite 690 Arsenomiargyrite 654 Arsenopyrite 652,688 Arva-Polhora, analysis of water 184 Arve River, analysis of water 94 Arzruni, A., cassiterite as a furnace product.353, 684 cuprite 662 hematite 347 INDEX, 769 Page. Page. Asbestos 384 Asbolite 534,694,695 Aschan, O., humus in natural waters 108 iron ores 531 waters of Finland 104 Ascharite 225,250 Ashburner, C. A., anthracite 753 classification of coals 756 Ashley, G. H., antimony deposits 690 formation of peat 742, 745 See also Blatchley and Ashley. Ashley, J. M., cited... 93 Askwith, W. R. , antimony mines 690 Aspasiolite 406 Asphalt 719,720-721 Assiniboine River, analysis of water 87 Aston , E . , analysis by 606 Astrakanite 223 Atacamite 265,662 Atherton, T. W. T., gold sulphide 643 Atlantic Ocean, analyses of water 123, 124 Atlin, spring near, analysis 191 Atmosphere, composition of 41-47 mass of 22 the primitive 53-57 Atomic weights 13 Atopite 691 Atrek River, analysis of water 166 Atterberg , A . , alteration of topaz 409 laterite 494 Attwood , G. , decomposition of diabase 288 Audoynaud , A . , ammonia in sea water 120 Auerbach F. , cited 202 Auerbach, H. S., tungsten deposits 700 Aug6, , bauxite 496 Augite 381-383 Austin, W. L., nickel ores 695 Autunite 707 Auvergnose 456, 458, 461, 462 Avalite 696 Awaruite 330,331,691 Awerkiew , N . , solubility of gold 647 Azurite 663 B. Babingtonite 382 Babitsee, analysis of water 104 Bacon, R. F., analyses cited 200 Bacteria as agents in rock decomposition 485 Bacterial precipitation of calcium carbonate . . 549 Bad Elster, analysis of water from 193 Baddeckite 391 Baddeleyite 711 Backstrom, H., fusion of micas 396,448 on Soret’s principle 309 synthesis of acmite 380 Baer, W., analyses of wood 739 Baerwald,C., pseud omorphs of chrysocolla.. . 662 Baeumler, , nickel in shale 691 Baeumlerite 225 Baikal, Lake , analysis of water 104 Bailey, E. H. S., analyses by 80, 187, 188, 715 zinc in mine waters 632 Bailey, E. H. S., and Case,E. C., analyses by . 182, 231 97270°— Bull. 616—16 49 Bailey, E. H. S., and Franklin, E. C., water analyses 80 Bailey, E. H. S., and Porter, F. B., analysis by 182 Bailey, G. E., California borates 246 soda niter 254 Bailey, R. K., analyses by 155 Bain, H. F., fluorite 582 lead and zinc deposits 675 Baker, A. L., bromine in bittern 233 synthesis of livingstonite 667 Baker, H. B., cited 49 Baker, T. , extracts from coal 764 Bakerite 248 Balatonsee, analysis of water 102 Balch, D. M., potassium chloride in algae 139 Baldacci, L., sulphur deposits 578 Baldauf, R., cryolite 336 Balland, , cited 66 Ballo, M. , water analysis 101 Balld,R.,and Dittler,E., mineral syntheses. 380 B allston waters , analyses 186 Baltic sea, analysis of water 123 Baltimoriase 464 Baltimorose 464 Bamberger, E . , fichtelite 745 Bancroft, G. J., origin of ore bodies 639 Bancroft, H. , platinum in dikes 702 Bandose 453,461 Bandrowsky, F. X., nitrogen in petroleum. . 718 Baragwanath, W. , platinum 704 Barber, W. B. See Nutter and Barber. Barbier, P., and Prost, A., composition of feldspars 364 Barbierite 364 Barbour, E. EL, and Torrey, J., siliceous oolite 544 Barcenite 664 Barchatow bitter lake, analysis of water. . . 171, 175 Baret, C. See Lacroix and Baret. Barima River, analysis of water 90 Barite 136, 537-539, 579-581 Barium, distribution 14 in sea water 121 Barkevikite 388,389 Barlow, A. E., nickel deposits 693,695 Barnard, H. E., analysis of water 71 Barnes, H. T. See Rutherford and Barnes. Barnitzke, J. E., kaolinization 492 Barr, W. M., analyses by. 75, 76, 77, 78, 79, 81, 82, 199 Cove Creek ac id water 199 Barrandite 520,522 Barrell, J., magmatic assimilation 310 Barrois,C.,chloritoid rocks 613 Barschall, H. See Van’t Hoff and Barschall. Bartow, E., waters of Illinois 63 Baras, C. , electricity in ore bodies 640 sedimentation 506 thermo-couple 291 water glass 297,298,585,637 Baras, C., and Iddings, J. P., electric con- ductivity of molten rocks 299 Barysilite 683 770 INDEX, Page. Basalt 450,456,460,468 fusibility 296,299 Basanite 441 Basch, E. E., syngenite and polyhalites 227 Basic rocks 466-469 Baskerville, C., analyses by 344, 696 vanadium in peat 705 See also Corse and Baskerville. Bassett, H., cited 154 Bassler, R. S.,silicification of fossils 558 Bastin, E . S . , colloidal gold 648 diagnostic criteria of metamorphic rocks . 624 origin of graphite 327 pegmatite 303,434 pyrrhotiticperidotite 335,466 secondary enrichment 639 Bastin, E. S., and Hill, J. M., magmatic sul- phides 335 See also Palmer and Bastin. Bastite 377 Baubigny , H. , synthesis of sphalerite 670 Bauer, H., and Vogel, H., cited 97 Bauer, K. , fusion of mineral mixtures 306 Bauer, M. , laterite 493, 494 nephelite in schists 373 Bauerman, H., and Foster, C. Le Neve, celestite 579 Baumann, A., and Gully, E., humus acids. . 484 Baumert, M., composition of dissolved air. . . 477 Baur, E . , hydrothermal syntheses 586 synthesis of quartz and tridymite 358 synthesis of quartz and feldspars 367 Bauxite .. 493-501 Bayldonite 682 Bayley, W. S., actinolite-magnetite schist 384 graywacke 540 iron ores 346,572 talcose schist 622 B earn, W . , water analyses 106 Bear River, analysis of water 156 Beaumont, E. de, distribution of the elements 13 volcanic emanations ^ 261 Beauvallet, P., vanadium in clay 705 Beaverite 681 B echamp, A . , equilibrium in mineral waters . 202 hydrogen sulphide and calcium carbon- ate 577 B echi, E . , origin of borates 245 distribution of vanadium 705 Bechilite 243,249 Beck, R., cassiterite in granite 353 diamond 325 gases from obsidian 283 magnetite 346 native copper 657 native silver 649 nickel deposits 693 ore deposits 626 primary gold 332 tin ores 685 Beck, R., and Fircks, W. von, copper ores 659 stibnite 690 Becke, F., amphibolite 592 changes of volume in metamorphism . . 588, 589 eclogite 599 graphic symbols 475 Page. Becke, F., hornblende pseudomorphs 386 saussurite gabbro 595 scapolite rock 597 specific gravity of igneous rocks 420 See also Stgp and Becke. Becker, A., fusion of hornblende 386 fusion of limestone 556 Becker, G. F., age of minerals 318,320 age of ocean 149,152 arsenic and antimony in sinter 689 borates 243 Borax Lake 160,243 constitution of amphiboles and pyroxenes 386 epidote from chlorite 597 eutectic classification of rocks 299, 423 formation of native sulphur 576 fractional crystallization in magmas 311 geological significance of wollastonite. . 378, 621 glaucophane rocks 388, 591 gold in sinter 645 heavy metals in granite 628 magma tic differentiation 309 mercury ores 664, 666, 668 minerals in sandstone 540 nature of magmatic solutions 299 oceanic chlorine 141 origin of petroleum 727 pore space in sandstone 538 radioactivity 317,318,320 serpentine 414,415,603 solvents of gold 646 Steamboat Springs 186, 206 viscosity of lava 309 waters of Sulphur B ank 197 Becker, G. F., and Melville, W. H., mercury in sinter 669 B ecquerel, A . C . , synthesis of dioptase 663 synthesis of lead ores 677, 679, 680, 681 Becquerel, H., and Moissan, H., free fluorine in fluorite 335 Bedson, P. P., barium in water 579 constitution of coal 764 gases in coal 759 paraffin in coal 748 Beegerite 678 Beemerose 445 Beerbachose 456,461 Beilstein, F., and Wiegand, E., ozokerite 719 Beisk, Lake, analyses of water 170, 174 saline deposits 234 Beistle, C. P. See Frear and Beistle. Belcherose 464 Beldongrite 534 Bell, J. B., platiniferous quartz 703 Bell, J. M. See Cameron and Bell. Bell, J. M., and Clarke, E. de C., mercury in sinter 668 Bell, R., corrosion of limestone 558 nickel deposits 693 Bellucci, G., chlorides in rain 52 B glohoubek, A . , water analysis 98 Bemmelen, J. M. van, absorbent power of hydrogels 501 absorption of potassium by clays 138,211 aluminum hydroxides 499 decomposition of rocks 492 INDEX, 771 Page. Page. Bemmelen, J. M. van, hydroxides of iron. . 529-531 laterite 494 tropical soils 499 zeolitic silicates in soil 211 Bemmelen, J. M. van, Hoitsema, C., and Ivlobbie, E. A., bog iron ore. . . 529,532 Bemmelen, J. M. van, and Klobbie, E. A., iron hydroxides 531 B enedicks , C . , sericitic rocks 593 Benedict, F. G., atmospheric oxygen 42 Bennett, J. See Haworth and Bennett. Benzene series 717 Beraunite 520 Beresovite 681 Berg, L., Sea of Aral 166 B ergeat , A . , boric acid from V ulcano 243 nontronite 491 occurrence of titanium minerals 352 ore deposits 626 volcanic sublimates 270 Bergenose 467 B ergius, F . , artificial coal 762 Berglund, E ., bromine in sea water 122 Bergstrasser, , cited 166 Bergt, , analysis by 544 Bertels, G. A., origin of petroleum 730 Berthelot, M., gases in native iron 288 origin of petroleum 726 synthetic hydrocarbons 723,724 Berthier, , synthesis of olivine 390 Berthierine 575 Berthierite 688 Bertrand, C. E., and Renault, B., origin of bitumen 733 Bertrandite 414 Berwerth, F., constitution of hornblende 387 Beryl 413,414 Beryl, gases from 275 Beryllium. See Glucinum. Beryllonite 414 Berzelianite 658 Best, A. See Coates and Best. Beudantite 682 B eyer , S . W . , clays 508 Beyerinck, M.W., cited Ill Beyrichite 692 Beyschlag, F., cobalt ores 691 See also Monke and Beyschlag. Beyschlag, Krusch, and Vogt, ore deposits. .. 626 Bickell, C., analysis by 207 Biddle, H. C., precipitation of copper 657 Biddle, H. J., nickel ores 695 Bieberite 694 Big Blue River, analysis of water 80 Big Lake, analysis of water 163 Biggs, J. W. H. See Clowes, F. Bigstone Lake, analysis of water 76 Biljo Lake, analysis of water 170, 177 Biltz, W., and Marcus, E., borates at Stass- furt 250 copper in Stassfurt salts 222 nitrates and ammonia in Stassfurt salts. . 223 See also Marcus and Biltz. Binder, G. A., solubility of cinnabar 667 solubility of sulphides 630 Bindheimite 683 Bingham, H. See Jamieson and Bingham. Binney, E. W., and Talbot, J. H., petroleum in peat 733 Biotite 392-396,601 Biquard, R. See Moureu, C. Bird, M., analysis by 182 Bisbeeite 663 Bischof, G., analyses by 101, 102, 172,505 cements in sandstone 538 dolomitization 567 gases in coal 760 origin of salt beds 220 reduction of silver sulphide 649 solvents of gold 646 sphalerite in sinter 671 zinc carbonate 673 Bischofite 224 Bismite 690 Bismuth, distribution 14 ores of 687-691 Bismuthinite 688 Bismutite 690 B ismutosmaltite 692 Bismutosphserite 690 Bistineau; brine, analysis of 182 Bitter Lake, analysis of water 170, 174 Bitterns 218,232,233 Bitumen 719,721 Bituminous coal 750-752 Bizio, G., lithium in sea water 120 Black Lake (California), analysis of water. . . 160 Black Lake (Roumania) 172 Black Sea, analysis of water 125 Blackwelder, phosphate rock 527 Blackwell, G. G., bauxite 497 Blairmorite 449 Blake, J. F., glaucophane schist 591 Blake, R. F., cited 45 Blake, W. P., bauxite 497 gilsonite and wurtzilite 720 primary gold 642 Terlingua mines 665 tin deposits 684,697 tungsten ores 699 zinc deposits 675,676 Blanc, G. A., radiothorium 315 Blanckenhorn, M. See Semper and Blanck- enhorn. Blatchley, W. S., clays 508 petroleum 735 Blatchley, W. S., and Ashley, G. H., marl. 550,551 Bleeck, A. W. G., jadeite 381 Bleicher, , iron ores 575 Blende 335,669 Bloedite 223,255 Blount, B. See Chadwick and Blount. Bluejoint Lake, analyses of water 161, 176 Blue Lick Springs, analysis of water 183 Blum, W., Great Salt Lake 155 Blum and Leddin, Carlsbad spriidelstein 204 Bobierre, composition of rainfall 52 Bobierrite . 521 Bode, G., cited 69 Bodenbender, G., wolframite 700 Bodlander, G., analysis by 573 melilite in Portland cement 399 7 72 INDEX, Page. Bodlander, G., sedimentation 506 Bodtker, clay 515 Boggild, O., cryolite 336 Boeke, H. E., borates in potash salts 250 bromine in potash salts 222 camallite and tachhydrite 224 fusion of carbonates 557 garnet 401 graphic representation of Stassfurt salts. . 224 iron in potash salts 225 rinneite 225 Bottcher, W. See Kramer and Bottcher. Boettker, E., Norwegian pyrite 335 Boghead mineral 733,740 Bog iron ore 530,571 Boleite 680 Bolley, P., origin of borates 245 Bolton, H. C., solubility of minerals in or- ganic acids 484 Bolton, W. von, recrystallization of diamond 324 tantalum 711 Boltonite 391 Boltwood, B. B., age of minerals 318 radioactivity of hot springs 215 Bone, W. A., and Coward, H. F., union of carbon and hydrogen 724 Bone, W. A., and Jerdan, D. S., synthetic hydrocarbons 724 Bonneville, Lake 154-157 Bonney, G. T., glaucophane eclogite 591 matrix of diamond 325 serpentine 602 Bonyssy. See Henriet and Bonyssy. Booth. J. C., and Muckle, A., Dead Sea 169 Boracite 225,250 Borates 225-253 Borax 243,247,250,256 Borax Lake, analysis of water 160, 176 borax from 243 Bordas, F. See Girard, C. Borgstrom, L. H., hackmannite 373 scapolite 404 Boric acid 243,244,270 Boriekite 520 Borne, G. von dem, radioactivity of granite. . 316 Bomite 335,658,659,660,741 Bomtrager, EL, analyses of peat 744 Borocalcite 243 Borodowsky, W., orpiment and realgar 689 Boron, distribution 14 in sea water 120 nitride 245 sulphide 245 Boronatrocalcite 248 Bosworth, T. O., Scottish sands 504 Bothamley, C. EL, analysis by 184 Boudouard, O., melting point of silica 293 Boulangerite 678 Bouquet, J., analyses by 191,205 spring deposits 204,205 Bouquet de la Grye, A., cited 126 Bourcart, E., Swiss lakes 95 Bourgeois, L., cassiterite in scoria 684 formation of perofskite 349 fusion of garnet 401 Page. B ourgeois, L. , synthesis of crocoite 681 of hydrocerusite 679 of iolite c 405 ofmeionite 404 of melilite and gehlenite 399, 400 of opal 357 of smithsonite 673 of spessartite 402 oftitanite 350 of wollastonite 377 Bourgeois, L., and TFaube, H., synthesis of dolomite 562 Bourgoin and Chastaing, analysis by 197 Boumonite 661 Boussingault, J. B., analyses by 199,233 carbon dioxide from volcanoes 46 Dead Sea 168 jet 746 manganese nodules 133 nitrate earth 253 origin of acid in volcanic waters 200 Boussingaultite 244 Boutan, E., diamond 326 Boutron-Charlard, A. F., and Henry, O., Dead Sea 169 Boutwell, J. M., camotite 709,710 Bowen, N. L., carnegieite 364 differentiation in silicate melts 312 fusion of enstatite 306 melting points of silicates 292, 357 nephelite 372 Bowen, N. L., and Andersen, O., forsterite. . . 390 magnesium metasilicate 312,377 melting points of minerals 292 Bownocker, J. A., petroleum 735 Bow River, analysis of water 88 Brackebuschite 682 Brackett, R. N., analyses by 81, 544 Brackett, R. N,, and Williams, J. F., rec- torite 611 Braconnier, •, analysis by 187 Bradley, F. H., unakite 598 Bradley, W. M. See Foote and Bradley. Braunlich, F. See Donath and Briiunlich. Bragard. See Fernandez and Bragard. Brand, A., artificial breithauptite 692 Brandenbourg, R . , water analysis 94 Branner, J. C., antimony deposits 690 bacterial decomposition of rocks 485 bauxite 498 clays 508 diamond 326 geological work of ants 485 magnesia in coral reef 567 novaculite 542 phosphorite 526 sandstone reefs 538 tallow clays 675 thermal disintegration of rocks 476 zinc deposits 675 Branner, J. C., and Newsom, J. F., phosphor- ite 526 Bransky, O. E. See Gilpin and Bransky. Branson, O . E. , origin of salt beds 220 Brauner, B., gold telluride 645 synthesis of hessite 652 INDEX. 773 Page. Braunite 533 Brauns, R., alteration of olivine 391 conchite 552 gold in a cement 646 graphite and molybdenite in basalt 328, 335 origin of salite 379 silvialite 404 theory of micas 397 webskyite 414 Bravo, J. J., vanadium ores 706 Brazier, J. S. , analyses by 5.13 Brazos River, analyses of water 82 Breckenridge, L. P., classification of ooals 759 Breese, C. M. See Failyer and Breese. Breitenlohner, J. J., on the Elbe 98 Breithauptite 692 Breunnerite 417,571 Brewer, W. H., sedimentation 506 Brewsterite 416 Briegleb, EL, synthesis of apatite 354 Briner, E., and Wroczynski, A., polymeriza- tion of acetylene 724 Brinsmade, R. B., cerusite deposit 679 Brochantite 662,663 Brock, R. W., gold in igneous rocks 642 platinum 704 Brodie, B. C., graphitic acid 754 synthesis of methane 279 Brogger, W. C., alteration of acmite to anal- cite 370,381 alteration of analcite 371 of arfvedsonite and barkevikite 389 of elseolite 373 classification of igneous rocks 425 composition of barkevikite 388 formula of asnigmatite 388 gibbsite and diaspore 498 magmatic differentiation 298, 308 nepheline syenites 446 nordenskioldine 684 occurrences of fluorite 335 of zircon 354 spreustein 375 sulphides in pegmatite 335 Brogger, W. C., and Backstrom, H., the gar- net group 374,401 Broggerite 707,708 Brokaw, A. D., solubility of gold 647 Bromine, distribution 14 in bittern 233 Bromly, A. H., tin deposits 685 Bromyrite 655 Brongniardite 653,678 Bronze, minerals formed on 657, 659, 662 Bronzite 376 Brookite 350-352 Brooks, A. H., tin deposits 686 Brooks, W. K., abundance of life in ocean 147 Brown, A. P., pyrite and marcasite 334 Brown, B. E., water analyses 83, 156 Brown, C. R. See Judd and Brown. Brown, F.C., geologic time 320 Brown, L. See Meadows and Brown. Brown, L. P., phosphorite 526 Browne, D. H., nickel deposits 693 Page. Brucite 414,564 Brugnatelli, L., titanolivine 389 Bruhns, W., synthesis of corundum 337 synthesis of hematite 347 of ilmenite 348 of quartz and tridymite 358 Brumell, H. P. H., petroleum 735 Brun, A., deposition of sulphur 270 fusibility of basalt 296 granite 434 melting points of minerals 292-294 origin of petroleum 727 synthesis of corundum 337 of hydrocarbons 723 of quartz and tridymite 359 of zoisite 406 volcanic gases 282-284 volcanic hydrocarbons 727 volcanism 282-284 water in muscovite 284 Brun, A., and Collet, L. W., volcanism ,, 282 Brunlechner, A., formation of iron ores 573 Brunswick well, analysis 183 Brush, G. J., pyroxene in slag 379 Brush, G. J., and Dana, E. S., alteration of spodumene 380 eucryptite 373 Brushite , 520 Buchanan, D. G., analysis by 255 Buchanan, J., section of nitrate deposit 254 Buchanan, J. Y., density of sea water 126 manganese nodules 132 marine mud 515 oceanic carbonic acid 144 Buchner, E. H., radioactivity of rocks 315 Buchrucker, L., babingtonite in slags 383 Buckley, E. R., clays 508 Bucking, H., occurrence of iolite 406 Buckley, E. R., and Buehler, H. A., zinc de- posits 675 Buckman, H. O., clays and kaolin 492 Buehler, H. A., and Gottschalk, V., analyses of mine waters 632 Buehler, H. A. See also Buckley and Buehler. Bujor, P., cited 172 Buluktii-Kul, analysis of water 171-175 Bunsen, R. W., composition of dissolved air 49,477 fundamental magmas 308 gases in rock salt 274 magmatic solutions 308 oxygen of the atmosphere 42 volcanic gases 261,262 Bunsenite 694 Burada, A., the Black Sea 122 Burchard, E. F., lignite 748 Burgess, G. K. See Waidner and Burgess. Burgess, J. A., halide ores of silver 655 Burrell, G. A., natural gas 714 See also Allen and Burrell. Burton, C. V., artificial diamond 324 Buseb, E. R., nickel deposits 693 Buschmann, J. O., von, Das Salz 230 Bushong, F. W., petroleum 717,735 774 INDEX. Page. Bushong, F. W., and Weith, A. J., analyses by 80,81 Busz, K., analysis by 495 corundum 338 Butler, B. S., epidote 407 plumbojarosite 681 Butler, B. S., and Gale, H. S., alunite 259 Butler, F. H., kaolinization 492 Biitsehli, O., calcareous organisms 553 Butte, Montana, mine water 189 Buttgenbach, G., Argentine borates 249,250 Byasson, H., origin of petroleum 726 Byerlite 721 Byerly, J. H. See Mabery and Byerly. Bygden, A., eutectics 302,423 Byske-elf, analysis of water 103 Bytownite 364 C. Caballero, G. de J., cobalt in Mexico 691 ramirite 706 Cabrerite 694 Cache la Poudre River, analyses of water 65 Cacoxenite 520 Cadell, H. M., cited on Stassfurt salts 221 Cadmium, distribution 15 ores of 669 Cady, H. P., and McFarland, D. F., compo- sition of natural gas 714 Caesium, distribution 15,28 in sea water 121 Cagniard-Latour, artificial coal 761 Cahaba River, analysis of water 74 Cailletet, L., hydrogen in iron 287 Calamine 672 Calaverite 645 Calb, G. See Jannasch and Calb. Calcareous algae 555,565 Calcareous sinter 203, 549, 550 Calcioferrite 520 Calciovolborthite 706 Calcite 247, 251, 417, 418, 537, 549, 551, 552 inclosing sand 537 Calcium, distribution 15 Calcium carbonate, circulation of 130 proportions on ocean floor 128-130 solubility of 128,129 Calculation of rock analyses 473 Calderon, C. S., Chaves, D. F., and Pulgar, P. del, glauconite 516 Caledonite 680 Caliche 254,255 California geysers 199 Californite 403 Calker, F. J. P. van, pseudogaylussite 158 Callainite 520 Calomel 664 Cameron, F. K., alkali in soils 242 water analyses 156 Cameron, F. K., and Bell, J. M., solubili- ties 229,478 Cameron, F. K., and Hurst, L. F., solubility of calcium phosphate 519 Cameron, F. K., and McCaughey, W. J., syn- thesis of apatite 355 Page. Cameron, F. K., and Seidell, A., solubility of calcium phosphate 519, 520 Campbell, H. D. See Howe, J. L. Campbell, J. M., laterite. 494 Campbell, M. R., borate deposits 246,248 classification of coals 757 Campbell, N. R., radioactivity 314,317 Campbell, N. R., and Wood, A., radioac- tivity 317 Campbell, W., and Knight, G. W., cobalt ores. 694 nickel deposits 693 Campbell, W. D., pseudomorph of gold 647 Campo, A del, ammonium fluoride in volcanic gases 261 rare metals in ores 669 Camptonite 456 Camptonose 456, 458, 461, 462 Canadase 462 Cancrinite 373-375 Cancrinite syenite 375 Canfieldite 653 Cannel coal 740, 751, 758 Cape Fear River, analysis of water 73 Caracolite 680 Carbides, metallic 723, 726, 727 Carbon, distribution 15 Carbon dioxide in the atmosphere 45-48 Carbonates in sea water 128-130 Carbonates, alkaline 237-242 origin of 210 Carbonic acid, oceanic 143-146 Carbonyls, metallic 330 Carborundum 326 Carles, P., barium and sulphates in natural water 204 fluorine in shells of mollusks 120 in spring water 192 Carlsbad Sprudel water, analysis 193 Carminite 682 Carnallite 224 Carnegieite 364 Carnelley, T., on periodic law 37 solubility of copper 656 Carnot, A., fluorine in phosphates 524 fluorine in sea water 119, 524 galena 676 minervite 522 phosphate rock 522-524 syntheses o f stibnite and bismuthin ite . . . 688 water analysis 172,197 Camotite 707,709 Caron, H. See Deville and Caron. Carpenter, W. L., oceanic carbonic acid.. 147,554 Carrollite 658,692 Carstone 541 Caryinite 682 Casares, J., fluorine in spring water 192 Case, E. C. See Bailey and Case. Case, W. H., zinc deposits 675 Casoria, E., palmerite 522 volcanic sublimates 271 Caspari, W. A., glauconite 517 red clay 513 Caspian Sea 165, 166, 175, 221 Cassel brown 748 Casseliase 465 INDEX, 775 Page. Casselose 459 Cassiopeium 21 Cassiterite 352-353, 683-687 Castorina, G. T., radioactivity of lava 315 Catapleiite 711 Catharinet, J., copper ores 660 gold in pegmatite 642 sperrylite in pegmatite 704 Cathrein, A. . alterations of garnet 402 chloritoid rock 613 epidotization 597 leucoxene 349 occurrence of chloritoid 395 pseudomorphs after gehlenite 400, 403 after scapolite 405 saussurite 595 titaniferous magnetite 348 Catlett, C., analyses by 558, 644 See also Clarke and Catlett. Cayeux, L., chalk 553 gaize 542 glauconite 516,518 glauconitic iron ore 531 oolitic iron ores 530, 575 phosphatic nodules 134 soils 508 Cecilose 464 Cedar River, Iowa, analysis of water 77 Cedarstrom, A . , cited 349 Celadonite. . . 1 517, 518 Celestite 247,578,579 Cellulose 738,739 Celsian 364 Celtium 13 Cementation, belt of 584 Cements in sandstone 537, 538 Centeno, J., analyses by 200 Cerargyrite 655 Cerite 711 Cerium, distribution 15 sources of 711-712 Cerusite 679 Cervantite 690 Cesaro, G., synthesis of crocoite and wulfen- ite 682 Cevollite 400 Chabazite 416,417 Chabrid, , Algerian saltpeter 253 Chadwick, O., and Blount, B., analysis by . . 106 Chalcanthite 662,663 Chalcedony 357 Chalcocite 658,659,660 Chalcophanite 672 Chalcophyllite 662 Chalcopyrite 335, 658, 659, 660, 741 Chalcostibite 661 Chalk 553 Chalmers, R., peat 745 Chalmersite 658 Chamberlin, R. T., borax lake of Ascotan. . . 249 gases from coal 760 gases from rocks 281, 286, 287 Chamberlin, T. C., carbon dioxide in atmos- phere 46,47 influence of oceanic carbonates on cli- mate 146,147 Page. Chamberlin, T. C., loess 510 planetesimal hypothesis 56, 140, 286 zinc ores 675 Chamberlin, T. C., and Salisbury, R. D., clays 507 volcanism 286 volume of ground water 33 Chamosite 397,574 Champex, Lac 95 Champlain, Lake, analysis of water 70 Ch amplainiase 467 Chance, H. M., origin of iron ores 529 Chancourtois, E. de, metals in earth’s interior 330 water analysis 169 Chandelon, J. T. P., cited 94 Chandler, C. F., analyses by 70,71,185,186 Chaper, M., diamonds in pegmatite 326 Chaplin Lake 163 Charante, G. M. van, analysis of water 529 Charcoal 760 Charcoal, fossil 745 Charitschkoff, K., synthetic hydrocarbons... 724 waters accompanying naphtha 732 Charlton, A. G., nickel ores 691 Charlton, H. W., analysis by 450 Chastaing, . See Bourgoin and Chastaing. Chatard, T. M., analyses by 64,156, 157, 159, 160, 161 , 237, 238, 239, 240, 382, 464, 465, 527, 541, 546, 558, 573, 615, 697 natural soda 239 origin of corundum 339 tallow clay 675 Chateau, , Algerian phosphates 524 Chattahoochee River, analysis of water 74 Chautard, J., lateritization 494 Chautard, J., and Lemoine, P., lateritization. 494 Chaves, D. F. See Calderon, C. S., etc. Chazal, P. E., phosphate rock 526 Chehalis River, analysis of water 86 Chdlif, River, analyses of water 67 Cheltenham waters, analysis 186,187 ,Ch£lu, A., sediment of the Nile 115,506 water of the Nile 106 Chemical denudation 111-118 Chenevixite 662 Cherrydale mineral water 197 Chert 542-545 Chester, A. H., on waters of New Jersey 71 Chester, F. D., epidotization : 598 Chevallier, A., cited 126 Chevandier, E., analyses of wood 739, 755 Chewaucan River, analysis of water 161 Chiastolite schist 614 Chicago drainage canal 109 Chichen-Kanab, Lake, analysis of water 164 Chiemsee, analysis of water 96 Chilenite 650 China Sea, analysis of water 125 Chippewa River, analysis of water 76 Chiviatite 678 Chloanthite 692,694 Chlorides in rainfall 52 Chlorine, distribution 15 in atmosphere 51-53 in potable waters 51,109,110 in sea water, origin of 139, 141 776 INDEX, Page. Chlorine, in volcanic gases 283 Chlorites 396-398 Chloritization 600 Chloritoid 393,395,612 Chloritoid-phyllite 614 Chlormanganokalite 271 Chlorophyllite 406 Chloropal 493 Chloropite 600 Chlorothionite 271 Chlorspodiosite 355 Cholesterin 735 Chondrodite 603 Chotose 447 Christie, W. A. K., Cis-Indus salt beds 228 See also Holland and Christie. Christy, S. B., synthesis of cinnabar 666 Chromic iron ore. See Chromite. Chromite 344,696,697 Chromitite 344 Chromium, distribution 15 ores of 696,697 Chrompicotite 344 Chrustschoff, K., artificial diamond 323 synthesis of hornblende 385 of mica 394 of quartz and feldspar 366 of quartz and tridymite 358,359 of zircon 354 Chrysocolla 663 Chrysolite 389 Chuard, E., alteration of bronze 659 Church, A. H., silicification of coral 515,543 Cimarron River, analysis of water 81 Cimolite 415,493,611 Cincinnati artesian well, analysis 182 Cinnabar 664-669,741 Ciplyte 523 City Creek, analysis of water 156 Claesson, C., dopplerite 744 Clapp, F. G., limestones 557 Claraz, G. See Heusser and Claraz. Clark, A. H., crinoids 565 Clark, G. F., cited 93 Clark, J. D. See Tolman and Clark. Clark, T. E., fichtelite 745 Clark, W. B., greensand 517 Clarke, F. W., age of ocean 149 alteration of iolite 406 analyses by 64, 156, 158, 183, 193,465,558,645,696 average abundance of minerals 419 average composition of igneous rocks 24-27 brucite-serpentine 415-606 chemical denudation 58, 115 clays 493 constitutional formula? 600 constitution of amphiboles 386, 388 of pyroxenes 383 cookeite 392 cryptomorphite' 251 evolution of the elements 12 formula of canerinite 374 glauconite and greenalite 517, 574 molecular weight of silica 361 roscoelite 392 Page. Clarke, F. W., solubility of minerals 480 specific gravity of igneous rocks 420 theory of chlorites 397 total run-off of rivers 58 zeolites 417 Clarke, F. W., and Catlett, C., nickel ore. . . 693, 704 Clarke, F. W., and Darton, N. H., iron mica. 391 Clarke, F. W., and Diller, J. S., alteration of topaz 408,409 nickel silicate 695 Clarke, F. W., and Schneider, E. A., calcina- tion of talc 415 formation of spinel 343 micas and vermiculites 396,398 Clarke, F. W., and Steiger, G., abundance of heavy metals 28,629 ammonium analcite and leucite 368 cadmium 669 vesuvianite... 403 Clarke, F. W., and Wheeler, W. C., echino- derms 565,566 Claude, G., composition of air 41,44 Claudetite 690 - Claus, C., phosphatic sandstone 539 Clausmann, P. See Gautier and Clausmann. Clausthalite 676,677 Claypole, E. W., tin deposits 687 Clays 507,508 dehydration of 610-614 plasticity of ". 502 Clays, oceanic 130-132, 512-515 Clear Lake, analysis of hot spring near 197 Clement, J. K. See Allen, E. T. Clements, J. M., iron ores 346,572 Clemm, W., silication of limestones 558 Clermont, P. de, and Frommel, J. solubility of sulphides 630,636 Cleveite 707,708 Climate, influence of carbon dioxide on 47,48, 146,147 Clinochlore 397,398 Clinoclasite 662 Clinohedrite 672 Clinozoisite 406 Clintonite 393 Cloez, S., hydrocarbons in iron 722,723,728 Clouet, J., synthesis of chromite 697 Clough, C. T., and Pollard, W., occurrence of olivine 391 Clowes, F., barytic deposits 579 barytic sandstones 539 Cowes, F., and Biggs, J. W. H., solubility of oxygen in sea water 141 Coal 738-765 Coates, C. E., and Best, A., petroleum 717 Cobalt, distribution 15 i n ashes of sea weeds 121 ores of 691-696 Cobaltite 652,692 Cochenhausen, E. von, water analysis 155 Codington, E. W., phosphate rock 527 Cohen, E., matrix of diamond 324 salt lake in Transvaal 173 Cohen, E., and Raken, M., solubility of cal- cium carbonate. 129 Cohen, J. B., and Finn, C. P., oils from coal. . 748 INDEX, 777 Page. Cohn, F., travertine 550 Cole, G. A. J., bauxite 496 Cole, G. A. J., and Little, O. H., calcite and aragonite i n fossils 552 Coleman, A. P., anthraxolite 754 corundum-nepheline syenite 339 heronite 371 magnetic assimilation 310 nickel deposits 693 Colemanite 247,248 Collet, L. W . , oceanic deposits 130 phosphatic nodules 134 See also Brun and Collet. Collet, L. W., and Lee, G. W., glauconite 517 Collier, A. J., tin deposits 686 Collier, P . , native platinum 701 Collins, H. F., mercury ores 664 Collins, J. H., nickel deposits 693 tin ores 684,685 Collins, W. D., analyses of water 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82 Collophanite 521,523 Collot, L., distribution of barium and stron- tium 579 Collyrite 611 Colomba, L., alteration of glaucophane 388 Colorado River (Argentina) , analysis of water. 91 Colorado River (Arizona), analysis of water. . . 82 flow of 82 Colorado River (Texas), analysis oi water 82 Coloradoite 644,664 Columbia River, analysis of water 84 Columbite 687,710 Columbium, distribution 15 sources 710 Colvocoresses, G. M., cobalt ores 695 Comanducci, E., copper and cobalt in volcanic ash 628 Conchite 552 Condit, D. D., minerals in sand 504 Conichalcite 662 Connarite 695 Connate waters 213 Conneautsville well, analysis 185 Consanguinity of rocks 308 Contamination of river waters 109 Convection in magmas 311 Cook, E. H., cited 46 Cook, G. H., clays 508 greensand marl 517 marl 550 native iron 328 Cooke, H . C . , secondary enrichment 649 Cooke, J. P., vermiculites 396 Cooke, W. T. See Mawson and Cooke. Cookeite 392 Cookose 462 Coolgardite 644 CoomarA-Swdmy , A. K. , Ceylonese graphite. . 327 corundum 338 minerals in limestone 623 Cooper, A. S., origin of petroleum 732 Copal. 741 Copiapo, Rio, analysis of water 92 Copper, distribution 16 in sea water 121 ores of 655-664 Page. Coppock, J. B., cited 125 Coquand, H., antimony ores 689, 690 bauxite 496 borates 245 itabirite 609 Coquina 555,558 Coral 525,555,558 silicification of 515, 543 Coral rock 551, 555, 567 Cordierite 338,405 Cornet, F. L., phosphatic chalk 525 Comet, J. See Renard and Comet. Cornish, V., and Kendall, P. F., calcite and aragonite in shells 552 Comu, F., acid reactions of minerals 478 color of salt 231 hibscnite 412 rock-forming apophyllite 416 tests for calcite and dolomite 564 See also Redlich and Cornu. Comu, F., and Vetter, F., aragonite sinter. . . 204 Coronadite / 534 Corongamite, Lake, analysis of water 173 Corse, M. B., and Baskerville, C., analysis by. 518 Corstorphine, G. S., matrix of diamond 325 Cortese, E . , hot springs of V enezuela 243 Cortlandtite 463, 464, 465 Cortlandtose 465 Corundophilite 397 Corundum 336-341 Corundum rocks 467 Corynite 692 Cosalite 653,678 Cossa, A., synthesis of scheelite 699 tellurium in sulphur 270 volcanic sublimates 270 Cossyrite 388 Costachescu, N., gases in salt 231, 731 Coste, E . , origin of petroleum 727 salt and oil 229 Cotunnite 679 Courantyne River, analysis of water 90 Cove Creek, U tah, sulphur bed 199 Covellite 658-660 Coward, H. F. See Bone and Coward. Cowen, J. L., arsenic mine 690 Cox, E. T., antimony ores 690 phosphate rock 527 Cox, G. H., zinc deposits 675 Craig, A. W., and Wilsmore, N. T. M., water analysis 173 Cramer, E., volatility of silica 273 Cransac, analysis of water from 197 Crater Lake, analysis of water 86 Craw, J. W., analysis by 198 Crawley, J. T., and Duncan, R. A., absorp- tion of potassium by soils. 211 Credner, H., native copper 656 Crednerite 662 Crenothrix 205 Crenshaw, J. L. See Allen, Johnston, and Crenshaw. Cresson, C. M., cited 71 Crinoids, composition of 565 Cristobalite 356-363 Crocidolite 388 Crocoite 681 778 INDEX. Page. Cronstedtite 397,575 Crook, A. R., molybdenite 698 Crook, T., dedolomitization 623 Crook, T., and Davis, G. M., fluorite in sand. 504 Crook, T., and Jones, B. M., geikielite 349 Crookes, Sir W., artificial diamond 324,325 Crookesite 658 Crosby, W. O., coloration of clay 508 sandstone dikes 541 Crosnier, L., crystallized sands 538 Cross, C. F., and Bevan, E. J., lignocellulose. . 739 Cross, W., analcite basalt 370 analcite in phonolite 449 classification of rocks 423, 425 epidote 598 garnet in rhyolite 402 phlogopite in wyomingite 395 quartz - alunite and quartz - diaspore rocks 259,497 sandstone dikes 541 topaz in rhyolite 409 See also Iddings and Cross. Cross, W., and Hillebrand, W. F., cryolite. . 336 Cross, Iddings, Pirsson, and Washington, quantitative classification 425-433 Crossite 388 Cruzy well, analyses 187 Cryohydrates 301 Cryolite 336 Cryophyllite 392,395 Cryptomorphite 251 Crystallization, fractional, in magmas 311 Cubanite ' 658 Cumberland River, analysis of water 78, 107 Cumberlandite 468 Cumenge, E. See Friedel and Cumenge. Cumengeite 680 Cummingtonite 384 Cundell, J. T., and Hutchinson, A., zincite. . 672 Cunningham, J. See Lloyd and Cunning- ham. Cunningham, J. A., order of deposition of minerals 307 Cuprite 662 Cuprobismutite 661 Cuprodescloizite 682 Cuproiodargyrite 655 Cuprotungstite 699 Curie, M. S., radioactivity 320 Curie, P., and Laborde, A., heat from radium. 314 Currie, J., cited, on Stassfurt salts 221 Curtis, J. S., gold and silver in quartz por- phyry 628 origin of lead ores 683 Cusack, R., melting points of minerals 292,293 Cushman, A. S., plasticity of clays 502 solubility of minerals ,. 480 Cushman, A. S., and Hubbard, P., extrac- tion of potash from feldspar 480 Custerose 465 Cyanite. See Kyanite. Cyanchroite 271 Cylindrite 678,684 Cymatolite 380 Cyrtolite 712 Czakd, E., helium in natural gas 714 D. Page. Dacite 453 Dafert, F. W., caliche 255 Dahllite 355,523 Dahms, P„ analysis by 590 Dale, T. N., slate 547 Dali, W. H., coquina 555 Dali, W. H., and Harris, G. D., Florida phosphates 521 Dallas, mineral spring near, analysis 189 Dalmer, K., metamorphosis of phyllite. 398, 410, 611 Dalton, L. V., origin of petroleum 735 Daly, R. A., average composition of rock types 420 evolution of limestones 557 magmatic differentiation in Hawaii 298 magmatic stoping * 310 origin of alkaline rocks 446 pre-Cambrian ocean 140 the fundamental magma 26 Damour, A. A., analysis by 207 Icelandic geysers 196 native platinum 701 predazzite 570 titanolivine 389 Damourite 391 Dan River, analysis of water 72 Dana, J . D . , dolomitization 567 gypsum and salt 228, 229 serpentine 603 volume of ground water 33 Dana, E. S., thinolite 158 See also Brush and Dana. Dana, E. S., and Penfield, S. L., lead silicate. 683 Danalite 214,672 Dannemorite 384 Danube River, analysis of silt 505 analyses of water 101, 107 Daphnite 397 Darapskite 249,254,255 Darapsky, L., Chilean borates 249 Chilean nitrates 254, 255 Darton, N. H. , Florida phosphates 521 See also Clarke and Darton. Darwin, C. , volcanic islands 312 Dathe, E ., scapolite rocks 597 Datolite 416 Daubr6e, A. , alteration of bronze 659 arsenic in sea water 120 arsenic and antimony in basalt 628 associations of platinum 703 calcination of serpentine 376 ferrous chloride in native iron 141 formation o f galena 677 ofhyaliteand zeolites at Plombieres.. 210 of olivine 390 fossil charcoal 745 origin of cassiterite 686 of native iron 329,330 sea water and volcanism 141, 286 solubility of orthoclase 367,478 synthesis of apatite 354 ofbrookite 351 of cassiterite 353,684 ofdiopside 379 ofenstatite 376 IttDEX, 779 Page. Daubr6e, A., synthesis of gahnite 673 of hematite 346,347 of quartz 357,358 of topaz 408 of willemite 673 of zinc ores 673 zeolites at Plombieres 210, 417 Daubr^e, A., and Meunier, S., native iron. . . 328 Daubr6eite 6.90 Daubr^elite 696 Daudt, H. W. , analysis by 163 David, T. W. E., glendonite 158 matrix of diamond 326 Davidson, W. B . M. , phosphate rocks 521, 527 Davies , D . C . , W elsh phosphates 525 Davies, G. M. See Crook and Davies. Daviesite 680 Davis, C. A., diatoms in peat 211 marl 550 peat 742 Davison, C. , loess 509 Davison, J. M. , platinum, etc., in meteorites . 703 Dawson, H. M. See Van’t Hoff, Kenrick, and Dawson. Dawson, J. W., origin of gypsum 251,576 peat 745 spore cases in coal 763 Dawsonite 499 Day, A. L., melting points of minerals 292, 296 Day, A. L., and Allen, E. T., fusion of feld- spars 292 sublimation of feldspars 273 syntheses of feldspars 304, 366 Day, A. L., and Shepherd, E. S., &kerman- ite silicate 398 formation of quartz and tridymite 360 lime silicates 292,302 phase rule 304 quartz glass 357 temperature of lava 282, 296 volatility of quartz 273 volcanic gases 269 Day, A. L., and Sosman, R. B., feldspars — 364 graphite 326 melting points of minerals 292,294 Day, D. T., filtration of petroleum 736 phosphate rock 528 platinum 702 Day, D. T., and Richards, R. H., platinifer- ous sands 702 Day, W. C., artificial asphalt 725 gilsonite 720 pitch coal 720 Dead Sea 167,168,174 Death Gulch, water from 205 De Benneville, J. S., potash in beryl 414 Debray, H. , synthesis of apatite 355 synthesis of pyromorphite 682 ofscheelite 699 of silver halides 655 See also Deville and Debray. Dechen, H. von, cerusite sinter 679 Decomposition of rocks 476-536 Dedolomitization 623 Dee, River, analysis of water 93 De Groot, H. , California borates 246, 247 De Gouvenain, , fluorine in V ichy water. 192 Page. De Launay, L. See Launay, L. De. Delaware River (Kansas), analysis of water. . 80 Delaware River (N. J.), analysis of water. . . 71, 107 Delebecque, A., Lac L6man 94 Delebecque, A. , and Duparc, L. , French lakes 94 Delesse, A., volume of ground water 33 Delessite 397 Delkeskamp, R., barium in natural waters. . 204, 539, 579 bauxite 496 vadose and juvenile carbonic acid 213, 215 Delvauxite 705 Demaret, L. , zinc deposits 668 Demargay, E . , vanadium 705 Demel, W.,dopplerite 744 Demerara River, analysis of water 90 Dermis, W. D., cited 248 Denudation, aerial 138 Denudation, chemical 111-118 Denver, spring near, analysis 187 Derby, O. A., Brazilian diamonds 326 Brazilian topaz 409 disintegration of rocks 482 gold on 1 imonite 645 manganese ore 535 novaculite^ 542 occurrence of monazite and xenotime 356 Derbylite 691 Desaulesite 695 Deschutes River, analysis of water 85 Des Cloizeaux, A., formation of anorthite 365 nickel ores 693 Descloizite 672,682 De Smet, Lake, analysis of water 163 Des Moines River, analysis of water 77 Deville, C. Sainte-Claire, dolomitization 560 fumar oles of V esuvius 264 Deville, C. Sainte-Claire, and Leblanc, F., boric fumaroles 245 volcanic gases 262,263 volcanic sublimates 270 Deville, H. Sainte-Claire, synthesis of cassit- erite 353,684 synthesis of hematite 347 of magnetite 345 of willemite 673 of zeolites 416 of zircon 353 titanium and vanadium in bauxite 500, 705 topaz 408 water analyses 94,97 Deville, H. Sainte-Claire, and Caron, H., synthesis of apatite 354 synthesis of cassiterite 353, 684 of gahnite 673 of pyromorphite 682 of rutile 351 of staurolite (? ) 410 of zircon 353 Deville, H. Sainte-Claire, and Debray, H., native platinum 701, 702 synthesis of cinnabar 665 Deville, H. Sainte-Claire, and Troost, L., occlusion of gases by glass 276 synthesis of greenockite and wur tzite 670 Deville, H. Sainte-Claire, and Wohler F., boron nitride 245 780 INDEX. Page. Devils Inkpoi, analysis of water 199 Devils Lake, analysis of water 163,177 Dewar, J., cited 44 Dewar, J., and Ansdell, G., gases in meteorites 287 Dewey, F. P., solubility of gold 647 Deweylite 415 De Wilde, P., gold in sea water 122 origin of petroleum 730 Diabantite 397,600 Diabase 460,461,488 Diallage 379 Diamond 322-326 Diapborite 653,678 Diaspore 495,498 Diatom ooze 131,512 Diatoms, as sources of petroleum 733 in peat 211 Dick, A. B., minerals in sand 503 Dickson, C., formation of barite 581 Dickson, C. W., nickel deposits 693 platinum ores 704 Dickson, E. See Holland and Dickson. Dieffenbach, O ., gold on siderite 645 Diersche, M. , origin of graphite 327 Diesel, W., tests for calcite and aragonite 552 Dietze, A., water analysis 92 Dietzeite 255,696 Dieulafait, L., ammonia in sea water 120 barite 579 bitumen in shale 730 boric acid in natural waters 196 Chilean nitrates 256 copper in sea water 121 lithium in sea water 120 manganese in sea water 121 manganese nodules 133 origin of borates 251,252 precipitation of iron ores 571 serpentine 604 strontium in sea water 121 sulphur deposits 578 thermochemistry of iron and manga- nese §35,536 vanadium 705 zinc and copper in rocks 628 zinc in limestone 674 in sea water 1 121 Diller, J. S., alteration of pyrope. 403 loess 510 melilite and gehlenite in slags 399 occurrence of perofskite 349 priceite 248 quartz basalt 362 sandstones 540,541 See also Clarke and Diller. Diopside 378,379 Dioptase 663 Diorite 456,488 Dipyre 404 Dissociation in magmas 299,303 Ditte, A., metals in the atmosphere 53 origin of vanadates 706 synthesis of apatite 354 of cassiterite 353,684 of cinnabar 666 of greenockite 670 Page. Dittler, E., melting points of silicates 294 synthesis of plagioclase 365 of wulfenite 682 See also Ballo and Dittler, Doelter and Dittler. Dittler, E., and Doelter, C., bauxite 499 Dittmar, W., analyses of dissolved air . . 142, 143, 144 analyses of ocean water 23,123 oceanic salts 23,119 water of Hayes River 87 Dittmarite 520 Ditroite 446 Dittrich, M., decomposition of rocks 487 relations between spring waters and rocks 212,501 Ditz, H. See Donath and Ditz. Divers, E., and Shimidzu, T., tellurium in sulphur 270 Dniester, River, analysis of water 104 Dodge, J. A., analysis of water 75, 76, 83 Doelter, C., alteration of andalusite 410 constitution of pyroxene 383 formation of augite 382 of anorthite 365 of magnetite 345 of melilite 400 of spinel 343,398 fusibility of rocks 296 fusion of clinochlore 398 ofepidote 406 of garnet 401 of glaucophane 388 of micas 343,396 of tourmaline 413 gehlenite in limestone 622 magmatic dissociation 299,303 melting points of minerals 292, 293, 295 solubility of minerals 352, 480,630,631,636,684,689 solvent of gold 646 stability fields of minerals 304, 307 synthesis o f acmite 380 ofboumonite 661 of cinnabar 665 of covellite and chalcopyrite 659 of feldspar 365,366 of galena 677 o f hornblende 385 ofjamesonite 678 ofleucite 369 ofmeionite 404 of mica : 394 of nephelite and kaliophilite 372 of olivine 390 o f pyrite and pyrrhotite 333 ofsulphosalts 654 of wollastonite 377,378 of zeolites 416 volcanic chlorine 141 volcanic explosions 285 Doelter, C., and Dittler, E., the silicate MgAhSiOs 387 Doelter, C. , and Hoemes, R. , dolomitization . . 567 Doelter, C., and Hussak, E., formation of anorthite 365 formation of melilite 400 of spinel 343 INDEX. 781 Page. Doelter, C., and Hussak, E., fusion of garnet. 401 of mineral mixtures 310 of vesuvianite 403 Doering, A., analyses by 92, 236 cited 164 Doherty, W . M. , manganese nodules 533 Dole, R. B., analyses of water 69, 70, 71, 72, 73, 74, 75, 76, 78, 79, 81, 82 brines of Silver Peak marsh 181 rejoinder to Shelton 153 statement of water analyses 59 Dole, R. B., and Stabler, H., chemical denu- dation 113 silt carried by rivers 506 Dolerophanite 271 Dolomite 247,417,559-571 Domeykite 658 Domingite 678 Domoshakovo, Lake, analysis of water — 170, 174 saline deposits 234 Don, River, analysis of water 93 Don, J. R., distribution of gold 642, 643 gold in sea water 121 solvent of gold 647 Donath, E., action of nitric acid on coal 749 extracts from coal 764 humus substances 750 Donath, E., and Braunlich, F., reactions of lignite 749 Donath, E., and Ditz, H., reactions of lig- nite 749 Donath, E., and Manouschek, O., hydro- carbons from coal 764 Dopplerite 744 Doss, B . , anatase pseudomorphs 350 artificial hematite 347 grahamite 720 melnikovite 334 pseudobrookite 349 sand in gypsum 537 synthesis of rutile and anatase 351 Doubs, River, analysis of water 94 Doughty Springs 204 Douglas, J. A., volume of molten minerals. . 296 Douglasite 224 Douro, River, analysis of water 94 Drabble, G. C., see Wedd and Drabble. Dragendorff, J. G. W., analysis of water 104 Drasche, R. von, eclogite 598 Drevermann, A., syntheses of lead ores 681 Drew, G. H., bacterial precipitation of cal- cium carbonate 549 Drown, T. M., chlorine maps 51 Duane, W., heat from radium 314 Duboin, A., synthesis of kaliophilite 372 synthesis of leucite 369 Dubois, E., atmospheric transport of salt 52 chemical denudation 149 circulation o f calcium carbonate 130 ratio of sodium to chlorine in rivers 139 Du Bois, G. C., laterite 493, 494 Ducatte, F . , sulphosalts of copper 662 sulphosalts o f lead 678 Ducloux, E. H., analysis of sea water 123 loess 509 mineral springs of Argentina 216 Page. Dudley, W. L., vivianite 520 Duffield, S. P., analysis cited 181 Dufrenite 520 Dufrenoysite 678 Dumas, J. B., origin of boric acid 245 synthesis of argentite 650 Dumble, E. T., grahamite 720 iron ores 575 Dumont, J., decomposition of potassium carbonate by clay 501 solubility of rocks 480 Dumortierite 412,616 Duncan, R. A. See Crawley, J. T. Dundasite 499,679 Dunin-Wasowicz and Horowitz, J., analysis by 186 Dunite 463,465 Dunn, E. J., diamond 325 Dunn, J. T., barium and strontium in mine waters 580 Dunn, W. H., analysis of salt 231 Dunnington, F. P., deposition of manganese. 536 titanium in clays 500 Dunose 465 Dunstan, W. R., laterite 494 Duparc, L., analysis of water 94 hot springs 552 transformation of pyroxene 384 Uralian platinum 702 See also Delebecque. Duparc, L., and Holtz, H. C., Uralian plati- num 700 Duparc, L., and Hornung, T., uralitization. 384, 589 ' Durand-Claye, L., cited 125 Durocher , J. , copper sulphide 659 liquation in magmas 312 synthesis of argentite 650 of cinnabar 665 of dolomite 559 of galena— 676 of greenockite and sphalerite 670 of pyrite 333 of stibnite and bismuthinite 688 of sulphosalts 653 the fundamental magmas 308 Durun Lake 165 Dust, atmospheric 53 Dutoit, A. L., matrix of diamond 325 Dutton, C. E., radioactivity and volcanism. . 316 Dwina, River, analysis of water 104 Dyscrasite 650 Dyson, F. W., radium in the sun 319 Dysprosium 16,711 E. Eakins, L. G., analyses by 187, 342, 382, 436, 445, 455, 456,458, 464, 465, 510, 511, 546, 558, 570, 614, 628 fluorine in fossil bone 524 xanthitane 350 Eakle, A. S., lawsonite 411 East Saginaw, brine, analysis of 182 Eaton, F. M. See Van Winkle and Eaton. Ebaugh, W. C., and Macfarlane, W., Great Salt Lake 155 Ebaugh, W. C., and Williams, K., Great Salt Lake 155 782 INDEX, Page. Ebelmen, J. J., synthesis of beryl 414 synthesis of bunsenite 694 of chromite 697 ofenstatite 376 offorsterite 390 of gahnite 672 of magnetite 345 ofperofskite 349 of rutile 351 Eberhard, G., scandium 19 Ecdemite 682 Echinoderms, comdosition of 566 Eckel, E. C., gypsum 232 limestone and cement 557 phosphorite 526 slate . 547 See also Hayes and Eckel. Eclogite 388, 402, 598, 599 Eddingfield, F. T., deposition of gold 648 Edenite 384 Edingtonite 416 E d wards, M . G . , aluminum hydrates in c lay . 499 Eger River, analyses of water 98 E gger , E . , analyses of water 97 Egglestone, W. M., fluorspar 582 Egleston, T., solvents of gold 646,647 Eglestonite 664 Ehrlich, F. See Kolkwitz, R. Eichleiter, C. F., arsenical spring 188 Eilers, A., platinum and palladium in copper. 704 Eisenhulh, K., analysis by 573 Eitel, W., sillimanite, 410 Elseolite 371 Elseolite syenite 445,487 Elaterite 719 Elbe River, analyses of water 98,99 Elbow River, analysis of water 88 Eldridge, G. H., asphalt 720,721 Florida phosphates 527 Electrical activity in ore bodies 640 Electrum 644 Elements, distribution 13-22, 39 nature 12 periodic classification 35-39 relative abundance 22-35 table of. 13 Ellis, E. E., zinc deposits 675 Ellis, W. H., anthraxolite 754 Ells, R. W., manjak 721 Elschner, C., phosphate rock 528 Elsden, J. V., chemical geology. . . s . 11 Elton Lake, analysis of water 169, 174 Embolite 655 Emerson, B. K., amphibolite 593 andalusite and sillimanite 612 emery 340 serpentine 602 Emery 336,501 Emmons, S. F., fluorite 582 loess 509 ores of Leadville 683 platinum 704 secondary enrichmen t 639 serpentine 603 silver in eruptive rocks 628 zinc ores 675 Page. Emmons, W. H., manganese and gold 647 molybdenite 335 secondary enrichment 639 Emmons, W. H., and Harrington, G. L., mine waters 631 Emplectite 661,662 Enargite 661,662 Endell, K., acids of moor waters 484 origin of kaolin 492 See also Smits and Endell. Endell, K., and Rieke, R., cristobalite 357,360 spodumene 381 Endemann, H., asphalt 721 Endlichite 682 Engelhardt, A., phosphate rock 524 Engelhardt, F. E., analysis by 182 Engler, C., artificial petroleum 725 origin of petroleum 730,733 Engler, C., and Lehmann, T., artificial pe- troleum 725 Engler, C., and Severin, E., artificial pe- troleum 725 Enstatite 376,377 Epecu6n, Lagoon, analysis of water 164, 174 Epiboulangerite 678 Epichlorite 397 Epidosyte 407,599 Epidote 406-408,597,598 Epidote rocks 597,598 Epidotization 597,598 Epigenite 661 Epistilbite 416 Epsomite 223,249,255 Erbium 16,711 Erdmann, — — , water analysis 169 Erdmann, E., blue rock salt 231 Stassfurt salts 221 , 222, 223, 226, 231 Erdmann, H., abundance of nitrogen 34 nitrogen in minerals 274 Erie, Lake, analysis of water 69 Erinite 662 Erionite 416 Erlau, River, analysis of water 101 Erof6ef, M., and Latschinoff, P., diamonds in meteorite 324 Erwin, R. W., cited 50 Erythrite 694 Erythrosiderite 271 Escher, B. G., igneous rocks 475 Essen, J. von, solubility of carbonates 549 Essequibo River, analysis of water 90 Essexose 444,459 Etard, A., and Olivier, L., reduction of sul- phates by microbes 577 Ettinger, . See Franck and Ettinger. Eucairite 653 Eucryptite 371,380 Euctolite 459 Eudialyte 711 Europium 16,711 Eutectics 301-304,423-424 Euxenite 707,710 Evansite 520 Evans, J. R., analyses of water 73, 74, 75, 78 Evans, J. W., analcite in monchiquite 370 quantitative classification 433 INDEX. 783 Page. Evans, N. N., analysis by 619 Eve, A. S., radioactivity 315 Eve, A. S., and McIntosh, D., radioactivity. 315 Everding, H., Stassfurt salts 221 Ewald, , analysis by 205 Ewing, A. L., limestone erosion 559 Excelsior Spring, analysis 191 Eydmann, E. See Kohlschiitter and Eyd- mann . F. Fahlunito 406 Failyer, G. H., barium in soils 14 See also Schreiner and Failyer. Failyer, G. H., and Breese, C. M., nitrogen compounds in rain 50 Failyer, G. EL, Smith, J. G., and Wade, H. R., composition of soil particles 504 Fairbanks, H. W., analcite-diabase 371 tin deposits 687 Fairchild, H. L.,planetesimal hypothesis... 56,140 Fairhaven Springs, analysis 193 Famatinite 661 Farr, C. C., and Florance, D. C. H., radium in rocks 315 Farrington, O. C., formula ofiolite 405 meteorites 40 Farup, P. See Van’t Hoff and Farup. Faujasite 416 Fayalite 389-391 Feld, W., synthesis of pyrite 334 Feldspars 363-368 alterations of 368 melting points 364 sublimation of 273 Femic minerals 426,427 rocks 463-466 Fennel, A. C. See Judge, J. F. Fenneman, N. M., petroleum 717 Fennor, C. N., resorption of olivine 298 silica 357,360 Ferberite 699 Fergusonite 712 Fermor, L. L., garnet 402 laterite 494,495 manganese ores 534 Fernandez and Bragard, analyses by 580 Fernandinite 707 Femekes, G., precipitation of copper 657 Ferrier, W. F. See Weeks and Ferrier. Ferrieresand Dupont, synthesis of bunsenite. 695 synthesis of zincite 672 Ferrodolomite 573 Fersmann, A. E., relative abundance of elements 26 Fibrolite 409 Fichtelite 719,745 Fiedlerite 680 Field, F., analysis by 574 silver in sea water 121 synthesis of copper minerals 662, 663 Finckh, L., igneous rocks 475 serpentine from gabbro 414 Finkbiner, N. M., analysis by 86 Finlay, G. I., calculation of norms 432 dumortierite 412 Page. Finlayson, A. M. , genesis of lead and zinc ores. 674 Firm, C. P. See Cohen and Finn. Fircks, W. von, tin deposits 685 See Beck and Fircks. Fischer, F., coal analyses 751 Fischer, H., formation of oolite 553 mercury deposits 668 Fischer and Rust, microscopic structure of coal 763 Fischer, T. See Wedding and Fischer. Fischerite 520 Fish Creek, analysis of water 88 Fisher, O., criticism of Joly 149 internal temperature of the earth 291 Fisher, W. W., water of Thames 93 Flagg, J. W., Chilean nitrates 254 Flechsig, R., analysis by 193 Fleck, H., water analysis 168 Fleck, El., and Haldane, W. G., carnotite 709 Fleischer, A., volume of molten basalt 296 Fleissner, H., Diamonds in slag 324 Fletcher, A. L., melting points of minerals... 292 radioactivity of rocks 315 See also Joly and Fletcher. Flint 542-545 Flint River, analysis of water 74 Florance, D. C. H. See Farr and Florance. Fliickiger, F. A., analysis by 199 Fluocerite 336 Fluorine, distribution 16 free, in fluorite 335 in mineral waters 68,192 in sea water 119 in volcanic gases 261 Fluorite 271,335,336,504,582 Fluorspar. See Fluorite. Foerste, A. F., Clinton iron ores 531 Forstner, H., wurtzite as furnace product 668 Fohs, F. J., fluorspar 582 Foote, E. A. See Koenig and Foote. Foote, H. W., analyses by 344,450,697 calcite and aragonite 551 See also Penfleld and Foote. Foote, H. W., and Bradley, W. M., analcite. . 368 nephelite 372 Foote, W. M., leadhillite 681 Forbes, D., borate from hot springs 252 Chilean nitrates 254 South American borates 249 Forbes, E. H. See Penfleld and Forbes. Forbes, R. H., and Skinner, W. W., water analyses 82 Forbesite 694 Forchhammer, G., chemistry of the ocean. . 119, 121 heavy metals in rocks 627 magnesia in shells and corals 555, 565 synthesis of apatite 354 Ford, W. E., formula of dumortierite 412 See also Penfleld and Ford. Forel, F. A., on Lac L6man 94 Formaldehyde in atmosphere 45 Formenti, C., bauxite 497 Formulae, constitutional 600-602 Forsberg, , cited 124, 126 Forsberg, E. See Geuther and Forsberg. Forsterite 389-391 784 INDEX. Page. Forstner, W., mercury ores 669 Foster, C. Le Neve, Owens Lake 239 See also Bauerman and Foster. Foulk, C. W., analysis by 182 Foullon, H. B. von, gummite 708 nickel deposits 693,695 rhodusite 388 Fouque, F., formation of melilite 399 magmatic differentiation 298 steam from Etna 260 volcanic gases 264, 266, 267, 268 Fouque, F., and Gorceix, H., boric fumaroles. 245 Fouque, F., and Michel-Levy, A., crystalliza- tion of silica 361 formation of hematite 347 of magnetite 344 ofmelanite 399,402 of nephelite 372 of spinel 343 fusion of biotite and microcline 369, 448 of scapolite rock 405, 596 scapolite gabbro 596 synthesis of augite 382 ofenstatite 376 of feldspars 365,366 of leucite 369 of melilite 399 of mica trachyte 394 of olivine 390 Fournet, J., synthesis of chalcopyrite 658 synthesis of zinkenite 678 Fox, C. J. J., carbon dioxide in sea water. . . 145 Fox, R. W., electrical activity in ore bodies. . 640 Foyaite 446 Fraas, O. F., formation of bitumen 731 Fraatz, T. See Werner and Fraatz. France, lakes of 94 Franchi, S., glaucophane rocks 591 jadeite rocks 381 Franchi, S., and Stella, A., lawsonitein schist. 411 Franck, L., and Ettinger, diamonds in steel. . 323 Franckeite 678,684 Francolite 523 Frank, A., iodine in potash salts 222 Frankforter, G. B., water from Death Gulch. . 205 Frankland, P. F., coal gas 756 water analysis 91 Franklin, E. C. See Bailey, E. H. S. Franklinite 672,676 Fraps, G. S., and Tilson, P. S., water of Rio Grande 82 Frazer, J. C. W., and Hoffman, E. J., experi- ments on coal 764 See also Kastle, J. H., etc. Frazer, P., classification of coals 756, 757 Frear, W., and Beistle, C. P., soils 508 Freeh, F . , carbon dioxide and climate 48 Freda well, analysis cited 185 Freda, G., volcanic sublimates 271 Free, E . E ., aerial denudation 138 Freis, R., fusion of mineral mixtures 306 Freieslebenite 653,678 Fremy , E ., artificial coal 761 humic substances in coal 748 synthesis of anglesite 680 ofeerusite 679 Page. Frenzel, A . , B olivian tin ores 684 formula of pseudobrookite 349 mine water 632 Fresenius, O. R., analysis by 184 manganese and iron in spring waters 535 Fresenius, H., analysis by 168 Friedel, C., diamond 323 lead oxychlorides 680 nesquehonite 563 synthesis of atacamite 662 Friedel, C., and Cumenge, E., carnotite 709 Friedel, C. and G., alteration of muscovite. 396 artificial cancrinite 374 conversion of muscovite into nephelite.. 372 formation of leucite 369 syntheses of feldspars 365, 366 Friedel, C., and Guerin, J., synthesis of ilmen- ite 348 Friedel, C., and Sarasin, E., formation of quartz and feldspar 366 synthesis of analcite 369 ofhopeite 672 ofphosgenite 679 of quartz and tridymite 358 of topaz 408 Friedel, G., hydration of analcite 368 lead oxychlorides 680 synthesis of corundum 337 of kaliophilite 372 Friedel, G., and Grandjean, F., synthesis of chlorite 398 Friedlander, J., artificial diamond 323 Friedmann, A., analysis by 168 Frieseite 653 Frio, Rio, analysis of water 92 Friswell, R. J., action of nitric acid on coal. . . 749 Frochot, M., tin deposits 687 Frommel, J. See Clermont and Frommel. Frtih and Schroter, peat 744 Fuchsite 391 Fuller, M. L., corrosion of quartz 363,481 volume of ground water 33 Fuller’s earth 508,736 Fumaroles 262-269 Fumaroles, boric 243 Funafuti, atoll of 568 Funk, W., decomposition of feldspars 480 Fyris, River, analysis of water 103 G. Gabbro 462,463 Gabbro-nelsonite 468 Gadolinite 712 Gadolinium 16,711 Gaertner, A., bog iron ore 530 Gagel, C., and Stremme, H., origin of kaolin.. 492 Gages, A., synthesis of serpentine 414 Gahnite 341,672 Gaize 541,542 Gale, H. S., carnotite 709,710 colemanite 248 salines of Great Basin 236 Gale, H. S., and Richards, R. W., phosphate rock 527 Gale, H. S., and Schaller, W. T., minerals of Searles Marsh. . v 247 INDEX. 785 Page. Gale, L. D., cited 154 Galena 335,676,677,741 Galenobismutite 678 Gallium, distribution 16,28,669 Ganomalite 683 Gans, R., clay silicates 500 Garda, Lago di, analysis of water 96 Gardner, R. F., analysis by 233 Garnet 400-403,598,601 Garnet rocks 598, 599, 624 Gamier, J., nickel deposits 693 Gamierite 695 Garonne, River, analysis of water 94 Garwood, E. J., calcareous algse 555 Gas, natural 714,715 Gases in coal 756,757-760 Gassner, L., phosphatization 558 precipitation of metals 641 Gaubert, P., cristobalite 357 Gaukhane Lake, analysis of water 169, 173 Gautier, A., arsenic in sea water 120 chemistry of volcanism 280-285 decomposition of galena 677 fluorine in volcanic gases 261 fumarole gases 261, 283, 284 galena 677 hydrogen in atmosphere 44 iodine in sea water 119 juvenile and vadose waters 213 minervite 521-523 nitrogen, argon, arsenic, iodine in granite. 437 occluded and volcanic gases 276-279 origin of nitrates 257 reduction of copper sulphide 657 thermal springs and volcanism 214 Gautier, A., and Clausmann, P., fluorine in natural waters 68, 120, 192 Gautier, F., tin deposits 686 Gay Lussac, cited 49 formation of hematite 346 Gaylussite 159,238,247 Gebbing, J., cited 95 Gebbart, H., synthesis of barite 581 Gedrite 383,384 Gedroiz, EL, humus in soils 484 Gegenbaur, V., water of the Adriatic 122 Gehlenite 398-400,601 Geijer, P., magnetite syenite 469 Geikie, Sir A., bog iron ore 530 elevation of continents 31 order of magmatic eruptions 310 saline matter in rivers 113, 114 temperature of molten lava 296 Geikielite 349 Geitner, C., synthesis of argentite 650 synthesis of beyrichite 692 of greenockite 670 of pyrite 333 Genesee River, analysis of water 70, 107 Genth, F. A., alteration of corundum 341 alteration of orthoclase to albite 368 of talc 384,415 analyses by 608 gummite 708 lansfordite 563 97270°— Bull. 616—16 50 Page. Genth, F. A., pseudomorphous cassiterite. . . 685 vermiculites 396 water of Dead Sea 168 Genth, F. A., and Penfield, S. L., nesque- honite 563 Genthite 695 Geocronite 678 Geological thermometer 228, 621 George, R. D., tungsten deposits 700 Georgiadesite 680 Gerhardtite 663 Germanium 16 Gersdorflite 692 Geuther, A., formula of gypsum 223 Geuther, A., and Forsberg, E., synthesis of wolframite 699 Geyserite 207 Gibb, A., and Philip, R. C., precipitation of silver sulphide 651 Gibbsite 495, 496, 498, 499 Gibson, J., analysis of manganese nodule. . 133, 134 See also Irvine, R. Giebeler, H., radium in Nova Geminorum. . . 319 Gigantolite 406 Gil, J. C., fluorine in spring waters 192 barium, etc., in spring waters 184 Gila River, analysis of water 82 Gilbert, G. K., Lake Bonneville 154 mirabilite at Great Salt Lake 234 salts of Sevier Lake 235 tufa 550 Gilbertite 391 Giles, W. B., bakerite.*. 248 Gilman, F., nickel deposits 694 Gilpin, J. E., and Bransky, O. E., fuller’s earth 736 Gilpin, J. E., and Schneeberger, P., fuller’s earth 736 Gilsonite 720 Ginsburg, A. S., synthesis of nephelite 372 Ginsburg, I., kaolin 492 Girard, C., and Bordas, F., spring deposits. . 204 Girardin, J. , magnesian travertine 561 Gismondite , 416 Glance coal 746 Glasenapp, M., niter in sandstone 253 Glaser, M. See Kalmann, W. Glaserite 223,228 Glass, occlusion of gases by 276 Glasser, B., nepouite 695 Glauberite 223, 228, 247, 249, 255, 270 Glaucochroite 389 Giaucodot 692 Glauconite 135,516-518,573 Glaucophane 387,388 G laucophane schists 591, 592 Gleditsch, E., uranium and radium 319 Glendonite 158 Glenn, W., chromite deposits 697 Glinka, K., glauconite 517,518 kaolin 499 weathering o f minerals 483 Globigerina ooze 131, 512 Glucinum, distribution 16 Gmelinite 416 786 INDEX. Page. Gmundenersee, analysis of water 96 Gneiss 487,618-620 Goebel, A. , cited 169 Gockel, A., radioactivity of rocks 315 Godeffroy, R . , analysis o f water 96 Gorgey , R., salts of Hall, Tyrol 227 Goessmann, C. A., analyses by 182, 233 Goethite.i 529 Gotz, J . , ottrelite rocks 613 Gold , distribution 16 in coal 646 in igneous rocks 332 in sea water 121,122 ores of 641-648 solvents of 646,647 Goldberg, A . , cited 193 Goldsberry, P. See Kraus and Goldsberry. Goldschmidt, V., composition of tourmaline. 413 Goldschmidtite 644 Gooch, F . A . , analyses by 203 Gooch, F. A., and Whitfield, J. E., analyses Goodenough Lake, analysis of water 162, 176 Goose Lake, analy sis of water 86 Gorby, &. S., petroleum 735 Gorceix, H . , volcanic gases 268 See Fouqud and Gorceix. Gordon, C. H., change of augite to horn- blende 590 nomenclature o f gneiss 618 Gorgeu , A . , analyses by 534 synthesis o f fay alite 390 ofnephelite 373 of pseudo- wollastonite 377 of pyroxene 379 ofspessartite 402 ofwillemite 673 of zincite 672 wad 533 Gortner, R. A. See Alway, F. J. Gorup-Besanez, E. von, formation of mag- nesian carbonates 561 Goslarite 672 Gosling, E. B., ozokerite 719 Goss, A . , water analysis 82 Gosselet, J., phy llites 613 Gossner, B., on glaserite 223 Gottlieb, E., analyses of wood 739, 755 Gottschalk, V. H., and Buehler, H. A., electrical activity in ore bodies . . 640 See also Buehler and Gottschalk. Gouvenain, C. A. de, alteration of bronze. . . 659 Goyder, G. A., sulvanite 706 Grabau, A. W., classification of sedimentary rocks 537 Graftiau, J., cited 45, 50 Graham, T., coUiery gases 760 gases from meteorites 287 Graham, T., Miller, W. A., and Hofmann, A. W., water of the Thames 93 Grahamite 706,719,720 Gramann, A., alteration of andalusite 410 Grand River, analysis of water 70 Grand Ronde River, analysis of water 85 Grandjean, , formation of dolomite 566 Page. Grange, J. , analyses of water 94 Granite 433-438,473,487 radioactivity of 316 sulphur waters from 203 Granitite 437 Grant, U. S., zinc deposits 675 Graphite 326-328,754 Graphitic acid 754 Graphitoid 754 Graton, L. C., tin deposits 353,686,687 See also Hess and Graton. Graton, L. C., and Murdoch, J., copper-iron sulphides 658 Gray, G., impurities in air 50,52 Graywacke 540,541 Great Salt Lake, analyses of water 155, 173 Greenalite 346,517,574 Greenlee, W. B., volume of ground water.. . 33 Greenockite 669,670 Greensand. See Glauconite. Greinacher, H., radioactivity 314 Greiner, E . , silicate fusions 307 Greisen 686 Greshoff, M., analysis by, cited 197 Griffiths, A. P., mercury ores 668 Grimsley, G. P., clays 508 gypsum 232,576 Griswold, L. S., novaculite 542 Groddeck, A. von, sericitic rocks 593 topazfels 408 Grossmann, M., gases from lava . 281 Grossularite 400 Groth, P. , constitution of kyanite 409 Ground water, volume of 33 Grout, F. F., average composition of Minne- sota rocks 25 copper in country rock 657 plasticity of clays 502 precipitation of gold 648 of silver 651 Grubenmann, U., crystalline schists 588 glaucophane rocks 588, 589, 591 Griinsberg, K. , carbonates of alkaline earths . 569 Grunerite 384 Griinerite-magnetite schist 610 Grinding, F., maucherite 692 Griinlingite 688 Guano 253,257,258,520,521,523 Guadalcazarite 664 Guanajuatite 688 Gurnbel, C. W. von, chloropite 600 compression of lignite 760 dolomite 565 glauconite 516,517 itabirite 609 origin of manganese nodules 132 Gunther, R. T., and Manley, J. J., water analysis 169 Gunther, S., interior of earth 57 Gurich, G., ore deposits 626 Gu4rin, J. See Friedel and Guerin. Gueymard, E., platinum in tetrahedrite 704 Guignet, E., action of nitric acid on coal 749 Guignet, C. E., wax from peat 733 Guitermanite 678 INDEX, 787 Page. Gulf of Mexico, analysis of water 123 Gully, E. See Baumann and Gully. Gummite 708 Gunnarite 692 Gunning, J. W., analyses of water 94,97 Gurlt, A., talc 605 tungsten deposit 699 Gustavsen, C. N., analysis of water 81 Guthrie, F., change of obsidian to pumice. . . 298 cryohydrates 301 eutectics 301-302,423 Gypsum ... 223, 226, 229, 232, 247, 250, 251, 255, 537, 576 Gyrolite 416 H. Habermann, J., formation of gypsum 576 Hackmannite 373 Haefcke, H., constitution of hornblende 387 Haefele, P. E., alteration of andalusite 410 Hagele, C. See Hell and Hagele. Haehnel, O., kaolinization 492 Haeussormann, F., and Naschold, W., coal analyses 753 Hager, L., salt deposits 229 Hague, A., origin of Yellowstone hot springs. 213 scorodite in spring deposit 208, 689 Hahn, H., hydrocarbons in iron 722 Haldane, W. G. See Fleck and Haldane. Hale, r». J., marl 551 Halite 224,247 See also Salt. Hall, A. A., oils from coal 748 Hall, A. D., and Miller, N. J. H., nitrogen in rocks 34 Hall, C. W., and Sardeson, F. W., dolomite. . 567 Hall, Sir J., artificial coal 761 fusion of limestone 556 Hall, R. D., and Lenher, V., tellurides. 645, 648, 652 Halley, E., age of ocean 148 Hallock, W., effects of pressure 651 Hall oy site 415, 493, 500, 611 Hallstatt, Lake of, analysis of water 96 Halotrichite 259 Halse, E., mercury ores 664 tin deposits 685 Hamberg, A., cited 142, 144 native lead 676 Hamilton, N. D. See Parr and Hamilton. Hammerle, V., silicate fusions 306 Hammerschmidt, F., cited 227 Hanamann, J., waters of Bohemia 98,99, 100 Hancock, D. See Phillips and Hancock. Hanks, H. G., California borates 243,246 Hanksite 247 Hannay, J. B., artificial diamond 323 occlusion of gases by glass 276 Hannayite 521 Harder, E. C., manganese ores 535 Hardin, M. B., analysis by 198 Hardman, E. T., analysis by 544 See also Hull and Hardman. Hardpan 484,530 Hardystonite 672 Harger, H. S., diamonds 325 Page. Harker, A., average composition of igneous rocks 25 crystallization of magmas 311 hybridism 308 origin of pegmatite 434 primary polite 406 quantitative classification of rocks 433 Harkness, R., dolomite 567 Harmotone 416 Harney Lake, analysis of water 161, 176 Harper, H. W., asphalt 721 Harperath, L., Argentine salt 231 petroleum and salt 735 Harrington, B. J., analysis by 590 bornite 658 hydrogen sulphide in calcite 274, 549 See also Adams and Harrington. Harrington, G. L. See Emmons and Har- rington. Harris, G. D., salt deposits 230 See also Dali and Harris. Harris, J. E., absorption in soils 501 Harrison, J. B., heavy metals in rocks 629 laterite 494 rain water 52 Harrison, J. B., and Jukes-Brown, A. J., coral rock ............................. 555 red clay 513 Harrison, J. B., and Reid, R. D., waters of British Guiana 90 Harrison, J. B., and Williams, J., chlorides in rain 52 nitrogen compounds in rain 50 Harrogate, analyses of waters 184 Hartite 719 Hartleb, R. See Stutzer and Hartleb. Hartley, W. N., gases in rocks 274 reduction of sulphates 148 Hartley, W. N., and Ramage, H., distribution of rare elements 28, 529, 648 Hartsalz 225 Harzose 452,453 Hasselberg, B., absence of uranium from sun. 319 Hasshagen, , water analysis 169 Hasslinger, R. von, artificial diamond 323 Hasslinger, R. von, and Wolff, J., diamond. . 323 Hastings, J. B., gold ores 642,643 origin of pegmatite 434 Hastingsite 387 Hatch, F. H., classification of igneous rocks. . 425 diamonds 325 Hatch, F. H., and Rastall, R. H.,dedolomiti- zation 623 Hatchettite 719 Hauenschild, G., predazzite 570 Hauer, K. von, analysis of water 172 Hauke, M.,eutecties 306 Hatty nite 214,373-375 Hatiynophyre 148 Haushofer, dolomite and magnesite 564 solubility of minerals 478 Hausmann, J. See Zaloziecki and Hausmann. Hausmann, J. F. L., wulfenite 681 Hausmannite 533 788 INDEX. Page. Hautefeuille, P., synthesis of enstatite 376 syntheses of feldspars 366 of greenockite and wurtzite 670 ofleucite 369 oflithium-aluminumsilicates 381 ofnephelite 372 of olivine 390 of perofskite 349 of quartz and tridymite 359 of rutile, brookite, and anatase 351 titanite 350 vanadinite 682 See also Troost and Hautefeuille. Hautefeuille, P., and Margottet, J., synthesis of quartz and tridymite 359 synthesis of staurolite (?) 411 Hautefeuille, P., and Perrey, A., crystalliza- tion of titanic oxide 351 synthesis of beryl 414 of corundum 337 of zircon 353 Hautefeuille, P., and Saint-Gilles, L. P. de, synthesis of mica 394 Hawes, G. W., alteration of granite 616, 617 analyses by 739,755 chloritization 600 native iron 328 Hawes, G. W., and Wright, A. W., gases in quartz 274 Hawkins, J. D. See lies and Hawkins. Haworth, E . , petroleum 717, 735 zinc deposits . 675 Haworth, E., and Bennett, J., native copper. 657 Hayes, A. A., distribution of vanadium 705 sodium iodate in Chilean niter 249, 255 South American borates 249 Hayes, C . W : , alunogen deposits 259 bauxite 497,498 corrosion of quartz 363, 481 iron ores 530 phosphatic sandstones 539 phosphorite 526 Hayes, C. W.,and Eckel, E. C., iron ores. . 530 Hayes, C . W . , and Kennedy, W . , salt deposits 229 Texas petroleum 717 Hayes, C. W., and Ulrich, E. O., phos- phorite 526 Hayes River, analysis of water 87 Hayhurst, W., and Pring, J. W., ozone in atmosphere 43 Haywood, J. K. , analysis by 195 Haywood, J. K., and Smith, B. H., analyses cited 186,197 Headden, W. P., action of water on orthoclase 481 alunogen 259 analyses of river waters 61, 65, 66 anthracite 753 bary tic sinter 204,580 carbonate waters 190 cubanite 658 natron 242 nitrates in soil .253 stannite 684 Heath, G. L., cited 69 Heazlewoodite 692 Page. Heberdey, P . , melilite and gehlenite in slags . . 399 wollastonite in slags 377 Hedburg, E . , zinc deposits 675 Heddle, M. F., analysis by 518 Hedenbergite 378-379 Hedrumite 446 Heider, A., analysis by 169 Heileman, W. H., water analyses 82 Hein, H., fibrous silica 357 Heinisch, W., graphite in soils 327 Heintzite 225,250 Helium, distribution 16, 41 generation from radium 317, 318, 319 in fumarole gases 268 in natural gas 714 in spring waters 180 Hell, C., fichtelite 745 Hell, C., and Hagele, C., artificial paraffin- - - 714 Helmhacker, R . , chromite deposits 697 Helvite 214 Hematite 271,346-348 Hempel, W. , melting points of minerals 292, 293 oxygen of the atmosphere . 42 volcanic gases 268 Henrich, F., cited 213,480 volcanic sublimates 271 Henriet, H., formaldehyde in atmosphere ... 45 Henriet and Bonyssy, ozone 43 Henriot, E ., redioactivity 317 Henriot, E., and Varon, G., radioactivity 317 Henwood, W. J., electrical activity in ore bodies 640 Heraeus, W. C., melting points of shales and clays 292 Herapath, T. J., and W., the Dead Sea 169 Herbst, C. , ocean water 123 Hercynite 341 Herderite 414 Heron Lake, analysis of water 76 Heronite 371,450 Hess, F. L., origin of camotite 710 Hess, F. L., and Graton, L. C., distribution of tin 684 Hess, F. L ., and Schaller, W. T., vanadium minerals 710 See also Watson and Hess. Hess, V. F. See Schweidler and Hess. Hess, W. H., cave nitrates 253 Hessite 652 Hessose 455,458 Heterogenite 694 Heubachite 694 Heulandite 416 Heumite 446 Heusler , F. , formation of hydrocarbons 731 Heusser,C., and Claraz, G., Brazilian dia- monds 326 Hewett, D. F., sulphur in Wyoming 577 vanadium ores 706 Hewettite 707 Heycock, C. T., and Neville, F. H., silver antimonide 650 Heyward , B . H. , tallow clays 675 Hezner , L. , amphibolite 592 eclogite 599 INDEX, 789 Page. Hibschite 412 Hicks , H. , phosphatic fossils 525 Hicks, W. B., analyses by 160 Hidden, W. E . , Llano County minerals 712 sperrylite 704 xenotime in granite 356 See also Judd and Hidden. Hidden, W. E., and Mackintosh, J. B., gadolinite, etc 712 Hidden, W. E., and Pratt, J. H., sperrylite.. 704 Hidden, W. E., and Warren, C. H., yttro- crasite 712 Hiddenite 379 Hieratite 270-271 Highwood River , analysis of water 88 Highwoodose 440 Hikutaia Spring, analysis 191 Hilgard, E. W., analyses by 83, 160,238 arid and humid soils compared 491 carbonates as solvents of silica 483 d isintegration of rocks 490 origin of alkaline carbonates in soil. 210, 241, 242 soils 508 Hilger , A . , analy s is of holothur ian 566 Hill, B. F., Terlingua mines 665 Hill, J. B.,and MacAlister,D. A., Cornish tin ores 684 Hill, J. M. See Bastin and Hill. Hill, R. T., salt deposits 229 Terlingua mines 665 Texas petroleum 717 Hillebrand , Sylvia, nephelite 372 Hillebrand, W. F., analyses by 188, 189, 191, 382, 435, 436, 437, 439, 440, 442, 444, 445, 447, 450, 453, 455, 456, 458, 461, 462, 464 , 465, 467, 508, 514, 534, 546, 548, 570, 573, 592,614,615, 619, 624, 632, 645, 708, 709 copper arsenates 662 distribution of vanadium 705 heavy metals in rocks 628 kleinite 665 patronite 707 quisqueite 707 rare-earth minerals 712 roscoelite 707 slate 547 zinc-bearing clay 675 See also Cross and Hillebrand. Hillebrand, W. F., Merwin, H. # E., and Wright, F. E., vanadium min- erals 707,710 Hillebrand, W. F., and Ransome, F. L., carnotite 709 Hillebrand, W. F., and Schaller, W. T., Terlingua minerals 665 See also Schaller and Hillebrand. Himmelbauer , A . , scapolite 404 Himstedt, F., radioactivity 315 Hinde, G. J., flint and chert 543 Hinden , F . , dolomite and limestone 564 Hinsdalite 682 Hiortdahl , T. , synthesis of jaipurite 692 Hiortdahlite 383 Hirschwald, J., nitrogen compounds in rain 51 Pago. Hitchcock, C. H. , albertite 720 phosphate rock 521 steatite 605 Hobbs, W. H. , allanite and epidote 408 secondary galena 677 tungsten deposit 699 Hodges, J. F., water analysis 93 Hodges, R. S., cited 74 Hodgkinsonite 672 Hogbom, A. G., cited by Arrhenius 48 dolomitization 565,566 Hoernes, R. See Doelter and Hoemes. Hoff. See Van’t Hoff. Hoffman, E. J. See Frazer and Hoffman. Hoffmann, E. W., solubility of minerals 479 Hoffmann, G. C., allanite in granite 408 analysis by, cited 181 baddeckite 391 native iron 332 native platinum 701 souesite 330,331 Hoffman, L., iron ores 575 Hoffmann, R., synthesis of nephelite 373 Hofman, H. O., eutectics in slags 302 Hofmann, J. F., formation of coal 738, 763 Hofmann-Bang, O., rivers of Sweden 103 Hoitsema, S. See Bemmelen, J. M., van, etc. Holland, P., and Dickson, E., decomposition of diabase 488 Holland, T. H., barite 581 bauxite 498 corundum rock 339 desert salts 235 disintegration of rocks 482 graphite in syenite 328 laterite 493 primary calcite 418 Holland, T. H., and Christie, W. A. K., the Sambhar salt lake 150 Hollandite 534 Hollick, A. See Kemp and Hollick. Holmes, A., age of earth 318 distribution of radium 316 laterite 494 radioactivity 318 Holmes, H. N., ozone in atmosphere 43 Holmes, J. A., peat 745 Holmium 17,711 Holmquist, P. J., cristobalite and tridymite. 359 synthesis of perofskite 349 Holmquistite 388 Holothurian, analysis of 566 Holtz, H. C. See Duparc and Holtz. Holway, R. S., eclogite 599 Hood, , analysis by 696 Hopeite 672 Hopkins, A. T., chlorine maps 51 Hopkins, T. C., limestones 557 Hopmann, H., water analysis 173 Hoppe-Seyler, F., formation of marsh gas 729 synthesis of dolomite 561 Hornblende 384 Homblendite 463 Horner, L., silt 505 Hornstein, F. F., native iron 328 790 INDEX, Page. Homung, F., origin of petroleum 730 Homung, M., analysis of red mud 513 Homung, T. See Duparc and Homung. Horowitz, J. See Dunin-Wasowiez. Horsford, E. W., cited 71 Horsfordite 658 Hortonolite 389 Horwood, A. R., calcite and aragonite in fossils 552 Hoskins, A. P., glauconite 517,518 Hovey, E. O., artesian well at Key West 569 cordierite gneiss 406 siliceous oolite 544 How, H., borates of Nova Scotia 251 Howard, C. C., natural gas 715 Howard, C. D., analyses by 78,714 Howe, E., magnetic sulphides 335 Howe, J. L., and Campbell, H. D., on Chi- chen-Kanab 164 Howlite 251 Huacachima, Lake, analysis of water 164, 177 Huantajayite 655 Hubbard, P. See Cushman and Hubbard. Hiibnerite 699 Hudleston, W. H., phosphatic fossils 525 Hudson, E. J. See Mabery and Hudson. Hiittner, K., gases in rocks 278 Hudson River, analyses of water 71, 107 Hughes, G., phosphate rock 521 Hull, E., cited 93 Hull, E., and Hardman, E. T., chert 542,543 Hulsite 684 Humboldt and Gay Lussac, cited 49 Humboldt Lake, analysis of water 159, 176 Humboldt River, analysis of water 159 Humboldt salt well, analysis 182 Humboldtine 741 Hume, W. F., loess 509 Humphreys, A. A., and Abbot, H. L., sedi- ment of Mississippi River 506 Humphreys, W. J., gases in atmosphere 42,43 rare earths in fluorite 335 volcanic dust and climate 48 Humus acids 107, 108, 484, 743, 748, 750, 761 Hundeshagen, L., platinum in wollastonite- . 703 Hungary, salt and warm lakes of 172 Hunt, A. E., bauxite 497 Hunt, T. S., abundance of petroleum 735 alteration of siderite 572 analyses by 69,185,198 cosmical atmosphere 54 formation of dolomite 560 on atmospheric carbon dioxide 47 origin of alkaline carbonates 241 primeval ocean 140 salt and gypsum 229 sedimentation 506 serpentine 604 See also Logan and Hunt. Hunt, W. F. See Kraus and Hunt. Hunter, J. F. See Larsen and Hunter. Hunter, M., analysis by 450 Hunter, M., and Rosenbusch, H., monchi- quite 449 Huntilite 650 Hunyadi Janos, origin of water 212 Page. Hurlbut, E. B., analysis by 442 Huron, Lake, analysis of water 69 Hurst, L. F. See Cameron and Hurst. Hussak, E., associates of diamond 326 chalmersite 658 leucite pseudomorphs 371 native iron 328 palladium gold 644, 703 perofskite-magnetite rock 349, 350 platinum and palladium 701 primary iolite 406 synthesis of wollastonite 377 See also Doelter and Hussak. Hussak, E., and Prior, G. T., derbylite, etc.. 691 Hussak, E., and Reitinger, J., monazite sand. 356 Hutchings, W. M., minerals in sand 503 ottrelite 613 willemite in slag 673 Hutchins, W. M., apatite in slag 355 clays and shales 547 Hutchinson, , cited 50 Hutchinson, A., Meigen’s reaction 552 See also Cundell and Hutchinson. Hutchinson, brine, analysis of 182 Hutton, R. S. See Pring and Hutton. Hyalite 357 Hyalophane 364 Hyalosiderite 389 Hyalotekite 683 Hydrargillite. See Gibbsite. Hydroboracite 225,250 Hydrocarbons 713-737 in lava 281 Hydrocerusite 679,682 Hydrogen, distribution 17 in atmosphere 44 Hydrogen dioxide in atmosphere 43 Hydrogoethite 529 Hydromagnesite 414 Hydronephelite 416 Hydrozincite 672 Hypersthene 376,377 I. Iceland, analysis of geyser water from 1% sinter from 196,207 volcan ic gases from 261 Iddings, J. P., consanguinity of rocks 308 fay alite-i n rhyolite 391 magmatic differentiation 298, 308 order of igneous eruptions 311 quartz basalt 362 rock diagrams 475 See also Barns and Iddings. Iddings, J. P., and Cross, W., primary allan- ite 407 Iddings, J. P., and Penfield, S. L., fayalitein rhyolite 391 Idocrase. See Vesuvianite. Idrialite 719 Igelstrom, L. J., molybdenum in hematite. . . 348 Igneous rocks 419-475 average composition 27 classification of 420-433 Ihlseng, M. C., phosphate rock 528 Ijolite 445 INDEX, 791 Page. lies, M. W., and Hawkins, J. D., precipitated zinc sulphide 671 Iletsk salt lake, analysis of water 171, 173 Illiacus, A. See Ramsay and Illiacus. Illinois River, analysis of water 77, 109 chlorine in 109 Illy4s Lake, analysis of water 172, 173 Ilmenite 348,349 Ilmenite-nelsonite 468 Ilmenite norite 467 Ilosvay, L. von, water analysis 102 Ilz, River, analysis of water 101 Imperial, Pennsylvania, analysis of brine 185 Indalself, analysis of water 103 Indian Ocean 125 Indium, distribution 17, 28, 669 Infusorial earth 542, 544 Ingalls, W. R., tin deposits 685 Ingol, Lake 104 Inn, River, analysis of water 101 Inostranzeff, A., native iron 331 native platinum 702 schungite 754 d’Invilliers, E. V., phosphate rock 521 Iodine, distribution 17 in sea water 119 in spring water 183 Iodobromite 655 Iodyrite 655 Iolite 338,405 Ionian Sea 122 Ionium 12,314 Iowa River, analysis of water 77 Ipatief, W., origin of petroleum 731 Ippen, J. A., amphibolite 592 eclogite 598 synthesis of cinnabar 666 Iridium . 17,700-704 Iridosmine 700,702 Irish Sea, analysis of water 123 Iron, distribution 17 hydroxides of 528-533 in sea water 121 meteoric, chlorides in 140 native 328-332 nitride 272 occlusion of gases by 287 Iron bacteria 530 Iron ore 528-533,571-575 titaniferous 467 Irvine, R. See Murray, Sir J. Irvine, R., and Anderson, W. S., phosphati- zation 558,641 Irvine, R., and Gibson, J., manganese nod- ules 133 Irvine, R., and Young, G., solubility of cal- cium carbonate 128 Trving, J. D., tin deposits 687 Irving, J. D., and Emmons, S. F., tungsten ores 699 Irving, R. D., native copper 656 quartzite 607 Irving, R. D., and Van Hise, C. R., chert 544 enlargement of quartz grains 538 Isar River, analysis of water 101 Iser River, analyses of water 98 Page. Is§re, River, analysis of water 94 Isochlors 51,149 Issyk-Kul, analysis of water 171, 175 Istrati, C. I., Roumanian salt 230 Itabirite 609 Itacolumite 326 J. Jaccard, A., origin of petroleum 730,734 Jackman, W; F., cited 69 Jackson, D. D., cited 51 Jacobsen, O., analyses of dissolved air 142,144 analysis of peat 743 resins in peat 745 Jacquot, E.,and Willm, E., mineral springs... 210 Jaczewski, L., origin of graphite 327 Jadeite 379,381 Jaeger, F. M., analysis by 532 Jaeger, F. M., and §imek, A., synthesis of spodumene 381 Jaeger, F. M., and Van Klooster, H. S., syn- theses of sulphides 654, 678 Jaffa, M. E., alkaline carbonates 241 Jaffe, R., pitchblende 707 Jaggar, T. A., and Palache, C., zoisite rock. . 595 Jahn, J. J., origin of petroleum 730 Jaipurite 692,693 James River, analyses of water 72, 107 Jamesonite 678 Jamieson, G. S., nickel-irons 330 See also Penfield and Jamieson. Jamieson, G. S., and Bingham, H., analysis of water 164 Janda, , uranium ores 707 Janeirose 447 Jannasch, P., and Calb, G., composition of tourmaline 413 Jannasch, P., and Weingarten, P., vesuvi- anite 403 Jannetaz, E., formation of anglesite 680 Janssen, J., volcanic gases 269 Jaqerod, A., and Perrot, F. L., helium 319 Jaquet, J. B., platinum in ironstone 703 serpentine 414,602 Jarman, J. L., analysis by 534 Jasper 357 Jaspilite 609 Java, rivers of 105 Jeffersonite 379,672 Jeffrey, E. C., origin of petroleum and coal . . 733, 740, 751 Jenkins, , analysis by 534 J enney , W . P . , artificial grahamite 720 recent blende 671 zinc deposits 675 Jennings, E. P., magmatic iron ores 346 Jensch, E., cadmium 669 Jensen, H. I., copper in andesite 629 origin of alkaline rocks 446 Jentzsch, A., German lakes 102 Jerden, D. S. See Bone and Jordan. J erem^ef , P . , chalcopyrite and chalcocite 660 pseudomorphous garnet 403 pseudomorphs after olivine 391 Jervis, W. P., Tuscan fumaroles 251 792 INDEX, Page. Jet 746,758 Joannis, A., fusion of limestone 557 J ockamowitz, A borax 250 Jodidi, S. L., organic matter of soils 108 Johansson, H. E., eutectics 302,423 John, C. von, humus acid in coal 748 kainite and camalite 227 Nile mud 505 John, W. von, native tantalum 711 John Day River, analysis of water 85 Johns, C., transition point of quartz 359 Johnson, B. H., and Warren, C. H., cumber- landite 468 Johnson, H. S., cited 101 Johnson, J. P., diamond 325 Johnson, L. C., Florida phosphates 521 Johnston, J., and Adams, L. H., effects of pressure 585,651 Johnston, J., and Niggli, P., metamorphism.. 583 Johnston, J. See also Allen, E. T. Johnston, R. A. A., analyses by 332,344 awaruite 330 Johnston-Lavis, H. J., absorption of rocks by magmas 310 quartz in basalt 299 V asuvian sublimates 271 Johnstone, A., action of water on micas 396 solubility of minerals 132, 479 Johnstrup, F., cryolite 336 Joly, J., age of the earth 140, 149, 150, 151 age of minerals 320 meldometer , 292 melting point of minerals 292,293 order of deposition of minerals 307,316 radium and geology 315 radium in rocks 317 radium in sea water 122 radioactivity and volcanism 317 sedimentation 506 sublimation of enstatite 273 volume of oceanic salts 24 volume of oceanic sediments 138 Joly, J., and Fletcher, A. L., pleochroic halos 320 Joly, J., and Rutherford, E., pleochroic halos. 320 Jones, E. J., barite modules 136 Jones, L. J. W., mine water 632 Jones, T. R., chert 542 peat 742 Jones, W. R., cited 206 Jones ville acid water, analysis 198 Jordan River, analysis of water 168 Jordan River (Utah), analysis of water 156 Jordanite 678 Jorissen, A., vanadium in delvauxite 705 Joseite 688 Josephinite 330,331,691 Joukowsky, E., eclogite 599 Jovitschitsch, M. Z., chromitite 343 Jowa, L., synthesis of selenite 229,576 Judd, J. W., alteration of plagioclase to scapo- lite 368 atoll of Funafuti 568 corundum rock 339 origin of scapolite 404, 596 pressure and chemical change 291 scapolite rock 596 Page. Judd, J. W., and Brown, C. R., Burmese co- rundum 339 Judd, J. W., and Hidden, W. E., ruby 339 Judge, J. F., and Fennel, A. C., analysis by. . 183 Judithose 444 Jukes Browne, A. J. See Harrison and Jukes Brown. Julien, A. A., alteration of spodumene 380 decomposition of pyrite 334 geological effects of humus acids . . . 108, 210, 484 phosphate rock 521 J uvenile waters 213 K. Kaersutite 389 Kahlenberg, L., and Lincoln, A. T., hydroly- sis of silicates 195 Kahlenberg, L., and Schreiner, O., borate ions 196 Kainite 223 Kaiser, E., African diamonds 325 alteration of basalt 500 decomposition of rocks 487 Kalamazoo River, analysis of water 70 Kaleczinzky, A., water analysis 172 Kalgoorlite 644 Kaliophilite 371 Kalkowsky, E., corundum granulite 339 Kallerudose 437 Kallilite 692 Kalmann, W., and Glaser, M., analysis by. 184, 188 Kanab Creek, analysis of water from near 185 Kanolt, C. W., melting points of oxides 292, 336 Kansas River, analysis of water 80 Kaolin 491-493,499 Kaolinite 415,491,500,611 Kapouran, analysis of water 185 Karaboghaz, Gulf 165,166,175,221 Karlsbrunn, analysis of water from 191 Karlsdorf waters, analysis 186 Karstens, K., volume of the ocean 22 Kasarnowski, H. See Wohler and Kasar- nowski. Kaskaskia River, analysis of water 77 Kastle, J. H., Frazer, J. C. W., and Sullivan, G., phosphatic chert 544 Katamorphism, zone of 584 Katwee salt lake, analysis of water 173 Katzer, F., analyses of Amazon water 91 analyses ox sea water cited 122 mercury deposits 668 Kauer, A., analysis by 187 Kauimann, F. G., dopplerite 744 Kay, G. F., nickel ores .-... 695 Kayser, E., carbon dioxide and climate 48 Kayser, R., sulphur in petroleum 718 Kedabekase 462 Kehoeite 672 Keith, A., zinc deposits 675 Keller, G., formation of limonite 571 Keller, H. F., and Lane, A. C., chloritoid — 393 Keller, O., volume of ground water 33 Kellermann, K. F., and Smith, W. R., bacte- rial precipitation of calcium car- bonate 549 Kelly, A., conchite 552 Kelsey, H. G., cited 183 INDEX, 793 Page. Kelvin, Lord, effect of pressure on fusibility. 291 primitive atmosphere 55 Kelyphite 403 Kemp, J. F., bornite in pegmatite 660 Franklin zinc ores . . . 676 gneiss defined 618 gravitative differentiation in magmas. . 311, 312 ground water 33 iron ores 469 magmatic magnetite 346 metamorphosed dolomite 623 molybdenite in pegmatite 335 nickel ores 694 ore deposits 626,634 platinum ores 332, 700, 702, 703, 704 relative abundance of elements 28 secondary enrichment 639 tellurides 644 Kemp, J. F., and Hollick, A., limestone 623 Kemp ton, C. W., tin deposits 685 Kendall, J., solubility of calcium carbonate.. 129 Kendall, P. F., calcite and aragonite in shells. 553 Kennedy, "W. See Hayes and Kennedy. Kennedy, W. T. See McLennan and Ken- nedy. Kenngott, A., alkaline reaction of minerals.. 478 composition of tourmaline 413 vesuvianite 403 Kendrick, F. B. See Van’t Hoff, Kendrick, and Dawson. Kentallenose 455,456 Kentrolite 683 Kentucky River, analysis of water 78 Kermesite 688 Kern-theorie 425 Kerner, G., water analysis 97 Kerosene shale 733 Kerr, W. C., marl 551 Kersantite 456 Kettner, C. H., analysis by 532 Keyes, C. R., borax deposits 246 genesis lead and zinc ores 675 gypsum 576 linnseite 694 loess 509 ore deposits 626 origin of cerargyrite 655 primary epidote 407 recent blende 671 ultimate source of ores 627 Kieserite 223,228 Kikuchi, , occurrence of iolite 406 Kilauea, gases from 269 Kilbrickenite 678 Kilroe, J. R., laterite and bauxite 494 Kimball, J. P., grahamite 720 iron ores 530,571 Kimberlite 325 Kinahan, G. H., bauxite 497 Kinch, E., sodium chloride in rain 52 King, C., internal temperature of the earth. . 291 King, F. P., Georgia corundum 339 Kingsbury , J. T . , waters of U tah 155 Kirk, M. P., and Malcolmson, J. W., Ter- lingua minerals 665 Kirunose 469 Page. Kisil-Kul, analysis of water 170, 174 saline deposits 234 Ki§pati6, M., bauxite 499 Kitchell, W., marl 550 Kitchin, E. S., and Winterson, W. G., argon and helium in minerals 274 Klaprotholite 661 Klarelf, analysis of w ater 103 Klarfeld, H. See Zaloziecki and Klarfeld. Kleinite 664,665 Element, C., analyses by 134,614 formation of dolomite 562 laterite 494 origin of petroleum 730 Klementite 397 Klemm, G., minerals in sandstone 540 Klobbie, E. A., analysis by 532 See also Bemmelen, J. M. van, etc. Knebelite 389 Knight, C. W., analcite trachyte 371 See also Campbell and Knight. Knight, H. G., water analyses 86,162 Knight, W. C., platinum in covellite. 704 Knisely, A. L., water analyses 86 Knop, A., enlargement of quartz grains 538 Knopf, A., Alaska tin deposits 686 platinum and palladium 704 Knopf, A., and Schaller, W. T., hulsite and paigeite 684 Knox, J., mercury sodium sulphide 666 Knox, W. J., impurities in rain 50 Knoxvillite 696 Kobellite 678 Koch, A., celestite and barite 579 . cited 349 Kochelsee, analysis of water 96 Kobrich , bauxite 496 Koehlichen, K., cited 222 Koehn, E., cited 101 Koene, C. J., primitive atmosphere 55 Koenenite 225 Koenig, A., genesis of diamond 326 Koenig, G. A., analysis cited 185 synthesis of domeykite 658 Koenig, G. A., and Foote, A. E., diamonds in meteorite 324 Konig, T., and Pfordten, O . von der, ilmenite. 348 Koenigsberger, J., radioactivity 317 temperature relations 295 Konigsberger, J., and Muller, W. J., syn- thesis of quartz and tr idymite ... 358 Konigsee, analysis of water 96 Konlite 719 Kottigite 672 Koettstorfer, J., iodine in sea water 119 Kohlmann, W., associates of cassiterite 353 Kohlrausch, F., hydrolysis of silicates 195 Kohlschiitter, V, and Eydmann, E., hair sil- ver 649 Koken, E ., carbon dioxide and climate 48 Koko-Nor, analysis of water 169, 177 Kolenko, B., hornblende pseudomorphs 386 Kolderup, C. F., analysis by 467 Kolkwitz, R., and Ehrlich, F., on the Elbe. . 98 Kolotoff, S., analysis of sea water 125 Koninck, L. L. de, synthesis of cinnabar .... 666 794 INDEX. Page. Koninckite 520 Kornerupine 381,613 Kosmann, H. B., silver halides 655 Koto, B., chloritoid rock 613 glaucophane rocks 591 piedmontite . 407 Kovaf, J., kyanite in limestone 410 Kramer, G., and Bottcher, W., origin of pe- troleum 730 Kramer, G., and Spilker, A., origin of petro- leum 730,733,734 Kragerite 469 Kraus, E. H., celestite 579 Kraus, E. H., and Goldsberry, P., copper-iron sulphides 658 Kraus, E. H., and Hunt, W. F., celestite — 538 Kraut, K., diffusion of cobalt and nickel 691 Kraze, K., Stassfurt salts 222 Kremersite 271 Krennerite 645 Kretschmer, A., composition of fahlerz 661 Kreusler, U., oxygen of the atmosphere 42 Kreutz, S., amphibole 387 the Meigen reaction 552 Krogh, A., annual consumption of coal 46 oceanic carbonic acid 143, 146 air from Greenland 46 Kriimmel, O., volume of the ocean 22 Kruft, L., phosphorite 524 Krugite 223 Krusch, P., platinum in graywacke 704 Krypton * 17,41,180 Kryptotile 393,611 Ktypeite 552 Kiimmel, H. B., clays ^ 508 peat * 742 Kuhlmann, F., phosphate rock 524 silication of limestone 558 synthesis of cerargyrite 655 Kulaite 459 Kultascheff, N. V., fusion of mixed silicates. 300, 302 Kunz, G. F., Montana corundum 340 Kunz, G. F., and Washington, H. S., Arkan- sas diamonds 325 Kunzite 379 Kupfier , A . E . , native iron 331 Kurnakoff, N. S., on Karaboghaz 165 Kurtz, C. M., analyses by 244 Kusnetsoff, S., on Karaboghaz 165 Kuss, H., mercury deposits 668 Kvassay, E . von, origin of alkaline carbonates 241 Kyanite 409,410,612 Kyanite schist 614 Kyle, J. J., Argentine borates 249 vanadium in lignite 706 water analyses 91 Kyschtymase 467 Kyschtymite 339,467 L. Laa bitter spring, analysis 187 Laach, Lake, analysis of water 172, 176 Laborde, A. See Curie and Laborde. Labradorite 364 Laby, T. H. See Mawson and Laby. Lachat, , celestite 579 Page. Lachaud and Lepierre, lead chromates 681 Lachmann, R., later ite 496 Lacroix, A., absorption of limestone by gran- ite 310 allanite and epidote 408 alteration of bronze 659 alteration of hornblende to auglte 386 alteration of serpentine 415 berthierine 575 boric acid in fumaroles 245 chalcocite on old coins 657 constitution of phosphorite 523 dumortierite in gneiss 412 eclogite rocks 599 formation, of zeolites 417 glauconite 517 ktypeite 552 later ite 494 miner vite 522 Mont Pelee 268,362 occurrence of lawsonite 411 phosphates of lime 523 phosphatized andesite 521 plancheite 663 recent cerusite 679 scapolite rocks 404, 597 spinel in troctolite 343 tridymite 362 villiaumite 373 volcanic sublimates 271 wollaston ite in aplite 378 See also Michel-Levy and Lacroix. Lacroix, A., and Baret, C., wemerite rock. . . 597 Lacroix, A., and de Schulten, A., Laurium slag minerals 680 Lacu Sarat, analysis of water 172, 174 saline deposits 234 Laczczynski, , analysis of chromite 344, 697 Ladd, G. E., clays 508 Ladureau, A., sulphur in atmosphere 45 Lagonite 243 Lagorio, A., eutectics 423 formation of leucite 370 fusibility and solubility distinguished. . . 307 glass-base 309 pyrogenic corundum 338,339 solubility of minerals in magmas 310 Lagoriolite 401 Lahontan, Lake 157-160 Laine, E. See Muntz and Laine. La Junta artesian well, analysis 191 Lake, P.,laterite 493,494 Lampadite 533,662 Lamprophyre 442 Lanarkite 680 Lane, A. C. , criticism of Brun 283 eutectics 302,423 magmatic gases 283 mine waters 631 native copper 656 the ocean 127 volcanism 283,285,286 waters of Michigan 70, 185, 212 See also Keller and Lane. Lane, A. C., and Sharpless, F. F., griinerite. 384 Lang, J., bauxite 496 INDEX. 795 Page. Lang, R., lublinite 551 Langbeinite 223,228 Lansfordite 563 Lanthanite 17 Lanthanum 17,711 Lapis lazuli 374 Lapparent, A. de, distribution of solfataras. . 212 Laramie lakes, analyses of water 163, 174 Laramie River, analyses of water 79 Larderellite 243 Larsen, E. S., perofskite rock 350,468 See also Washington and Larsen; Wright and Larsen. Larsen, E. S., and Hicks, W. B., scarlesite. . 247 Larsen, E. S., and Hunter, J. F., melilite rock 400 Larsen, E. S., and Schaller, W. T., cevollite. 400 Lartet, L., on Dead Sea 168,561 Lasaulx, A. von, alteration of rutile 348 kelyphite 403 sulphur deposits 577 See also Sartorius and Lasaulx. Laschenko, P. V., aragonite 551 Lasne, H., phosphorite 528 Laspeyres, H., olivine as a furnace product. . 390 sericite 593 Lassenose . 435,453 Lateral secretion 627 Laterite 493-501 Latite 451,452 Latouche, T. H. D., and Christie, W. A. K., analysis by 173 Latschinoff, P. See Erofeel and Latschinofl. Lattermann, G. , bary tic sinter 580 Lattimore, S. A., analysis by 235 Laubanite 416 Laumontite 416 Launay, L. De, average composition of igneous rock 26 cited 213 diamond 325 magmatic w aters 634 mean atomic weight of lithosphere 26 ore deposits 626,638 Laur, F., bauxite 496 gold and silver in Triassic rocks 641, 642 Laurdalite 446 Laurdalose 442,444 Laurionite 680 Laurite 19,700 Laurvikose 440 Lautarite 17,255 L&venite 383 Lawrenceite 140 Lawson, A. C., chert 543 corundum rock 339 mine water 631 See also Adams and Lawson. Lawson, A. C., and Palache, C., chert 543 Lawson, R.W., age of earth 318 Lawsonite 411 Lazurite 214 Lead, distribution 17 from uranium 317 occurrence in a coral ores of 676,683 Page. Leadhillite 681 Lebedintzeff, A., water analyses 166 Leblanc, F. See Deville and Leblanc. Lechartier, G., synthesis of mimetite 682 syntheses of olivine 390 synthesis of pyroxene 379 Le Chatelier, H., Algerian alkaline deposits.. 241 clay substances in marl 559 constitution of clay silicates 493 formation of granite 434 fusion of limestone 557 modifications of quartz 360 thermocouple 291 Le Chatelier, H., and Wologdine, S., graphite 326 Lechler, M., Bavarian waters 101 Leckie, J. S., nickel ores 695 Le Conte, J. , N evada borates 246 Le Conte, J., and Rising, W. B., mercury deposits 668 Leddin, . See Blum. Ledoux, A. R., nickel ores 695 Leduc, A., hydrogen in atmosphere 44 Lee, G. W. See Collet and Lee. Lee, W. T., Cove Creek sulphur 199, 578 Leffman, H., waters of Yellowstone Park 196 Lefort, J., analysis by 200 Legendre, R., carbon dioxide in air 46 Leguizamon, M. M., water analysis 164 Lehder, J. , phosphatic nodules 528 Lehrbachite 664,676 Lehmann, B., sericitic rocks 593 Lehmann, T. See Engler and Lehmann. Leibius, A. , gold 643 Leighton, H. See Newland and Leighton. Leighton, M. O., analyses of water 70 normal and polluted waters no Leith, C. K., actinclite-magnetite schist 384 glauconite and greenalite 517, 573, 574 origin of magnetite 346 See also Van Hise and Leith. Leith, C. K., and Mead, W. J., iron ores 531 Leitmeier, H., dimorphism of calcium car- bonate 551,563 spring deposits 204 Lekene 719 Leman, Lac, analysis of water 94 Lemberg, J., alterations of feldspar 368 alteration of spodumene and jadeite 381 of topaz 409 artificial cancrinite 374 chlorite pseudomorphs 398,402 composition of sodalite 374 decomposition of rocks 487 double decompositions in silicates 501 epidotization 598 fusion of limestone 556 kaliophilite and nephelite 372 leucite and analcite 368,369 predazzite 570 primitive atmosphere 55 reactions with andalusite and kyanite ... 410 with gehlenite 400 serpentine 602,603 silication of limestones 558 syntheses of zeolites • 417 tests for calcite and dolomite 558, 564 796 INDEX, Page. Lem6tayer, P., water analysis 92 Lemi^re, L., formation of coal 763 Lemoine, P. See Chautard and Lemoine. Lenarcic, J., formation of augite 382 formation of magnetite 345 ofnephelite 373 fusion of mineral mixtures 306 recrystallization of albite 366 Lenecek, O . , predazzite 570 Lengenbachite 678 Lengyel, B. von, analysis of water 172 Lenher, V., gold telluride 645 solution of gold 647,648 See also Hall and Lenher. Lenicque, H., carbide theory of volcanism. . . 281 origin of petroleum 728 primitive atmosphere 56 Lenk, H., augite-scapolite rock 405 Lenox, L. R., corals 555, 567 Lenz, O., itabirite 609 Lenz, R . , laterite 494 Leonard, A. G., gas well 729 zinc deposits 675 Leonite 223 Lepape, A. See Moureu and Lepape. Lepidolite 392-396,686 Lepidomelane 393 Lepidophseite 534 Lepierre, C., fluorine in spring waters 192 Lepsius, B., composition of dissolved air 477 Lepsius, It., glaucophane schists 591 Lermondose .' 466 Lesley, J. P., grahamite 720 Lesquereux, L., origin of petroleum 732 Letheby, H., water analyses 106 Letts, E. A., and Blake, R. F., carbon dioxide in air 45 Leube, G. , dolomite 564, 565 Leucite 368-371 melting point 292 Leucite basalt 459 Leucite rocks 447,459 Leucite syenite 447 Leucitite 447 Leucopyrite 688 Leucoxene 349 Leuk, analysis of water 187 Levat, E. D., gold and silver in diabase 629 nickel ores 695 phosphate rock 526 Leverett,F., loess 509 Leverrierite 393,611 Levi, M. G., radioactivity of lava 315 Levin, M. , decay of uranium 317 Levin, M. , and Ruer, R. , radioactivity 314, 317 Levings, J. H., gelatinous silica in ore bodies. 357 Levison, W. G., decomposition of rocks 477, 481 L6vy. See Miehel-L£vy; Fouqud and Michel- L4vy. Levy, A. , nitrogen compounds in rain 50 Levynite 416 Lewin, L. See Schweinfurth and Lewin. Lewis, H. C., origin of diamond 325 Lewis, J. V., North Carolina corundum 339 See also Pratt and Lewis. Lewisite 691 Lewy, H., analysis by 199 Lherzolite 463,464 Libbey, W. , volcanic gases 269 Liebenow, C. , radioactivity 316 Lieber , O . M. , itabirite 609 Liebert, H. , uranium in coal 710 Liebisch, T. , silver antimonides 650 Liebrich, A. , bauxite 496, 497 Lienau,H., bauxite 498 Lignin 739 Lignite 706,745-750 Lignocellulose 739 Lignone 739 Lillianite 678 Limburgite , fusibility 296 Limburgose 459 Limestone 548-559, 620-624 average composition 28 formation of 129-130 Limnite 529 Limonite 529-530,571-573 Linarite 680 Linek, G. , associates of spinel 342 oolite 553 origin of clay 492 origin of dolomite 560 orthoclase in dolomite 622 solubility of calcium carbonate 129 troilite 332 Lincoln, A. T. See Kahlenberg, L. Lincoln, F.C., gold 646 magmatic gases 290 Lindemann, B., minerals in limestone 623 Lindgren, W., analcite in rocks 370, 449 brochantite 663 chalcocite 660 fluorite in sinter 204 magmatic magnetite 346 magmatic waters as vein fillers 213 monazitesand 356 native copper 656 Ojo caliente 191 ore deposits 634,635 orthoclase as a gangue mineral 368 pseudomorphous galena 677 sericite and calcite 594 sodalite syenite 375 stibnite in sinter 689 tin deposits 686 tungsten ores 700 Lindgren, W., and Hillebrand, W. F., corona- dite 534 Lindgren, W., and Whitehead, W. L., jame- sonite 678 Linnaeite 692,694 Linosite 389 Liparite 434 Liparose 435,437,473 Lipp, A., analysis by 184 Lisboa, A. , monazite sand 356 Litchfieldite 446 Lithiophilite 687 Lithium, distribution 17 in sea water 120 Lithosphere, average composition 24-35 volume of 22 INDEX. 797 Page. Little, G., lead selenide 677 Little, O . H. See Cole and Little. Liveing, G. D., cited 44 Liversidge, A., analyses by 185, 696 bog iron ore 532 cobalt ores 695 coral 555 distribution of silver 648 gold in recent pyrite 645 in sea water 121 in rock salt 641 mercury in sinter 668 precipitation of gold 648 silver in sea water 121 solvents of gold 646 Livingstonite 664,667 Ljubavin, N., cave earth 253 Ljusnan, River, analysis of water 103 Lloyd, S. J., radium in sea water 122 Lloyd, S. J., and Cunningham, J., radium in coal 741 Loch Baile a Ghobhainn, analysis of water... 93 Locke, J. M. , uintaite 720 Lockyer,J.N., cited 12 Loebisch, W., and Sipocz, L., water analysis. 125 Lollingite 335,688 Loess. 509-511 Loew, O., analyses by 82, 156, 160, 236 Loewe, L. , cited, on Stassfurt salts 221 Lowenstein, H. , clays 500 Loewinson-Lessing F., average composition of igneous rocks 26 classification of igneous rocks 425 eutectics 423 fractional crystallization 312' magmatic differentiation 298, 305, 308 origin of volcanic gases 280 solubility of minerals in magmas 310 Loewite 223,228 Logan, W. E., and Hunt, T. S., phosphatic shell 525 Lohmann, P . , eclogite 599 Loire, River, analysis of water 94 Lonar Lake, analysis of water 173, 176 Long, J. H., cited 69 Longbanite 691 Lorandite 688 Lord, E. C. E., analysis by 462 Lord, N. W. , coal 750 Lorenz, N. von, water analysis 96 Lorenz, R., synthesis of greenockite and wurtzite 670 synthesis of troilite 333 Lorenzen, J., graphite in basalt 328 Loretz, H . , iron ores 575 Losanitsch, S. M., chromiferous clays 696 Lossen, C., itabirite 609 quartzite 607 Lossen, K. A., albite alterations 594 Lossenite 682 Lossier, L., water analyses 94 Lost River, analysis of water 86 Lotti, B . , copper ores 659 stibnite and cinnabar 689 Louderback, G. D., radioactivity and vol- canism 317 Page. Loughlin, G. F., clays 508 Louisville artesian well, analysis 186 Lotz, H., cited 483 Lozinski, V. von, chemical denudation 149 Lublinite 551 Luca, S. de, analysis by 199 Lucas, A., chemistry of the Nile 106 natural soda 239 Lucas, R . , physical properties of clays 502 Ludlamite 520 Ludwig, A., artificial diamond 323 Ludwig, E., analyses by 188, 191 Ludwig, F., analyses by 104, 170,234 Ludwig, F. J. H., analysis by 205 Luedecke, O., water of the Oder 102 Luedeking, C., lead chromates 681 Luedeking, C., and Wheeler, H. A., barite. 580,581 Luneburgite 250 Lujavrose 444 Lukens, H. S., scandium in wolfram 19 Lunge, G., cited, on Stassfurt salts 226 natural soda 239 Lunge, G., and Millberg, C., solubility of quartz 363 Lunge, G., and Schmidt, R. E., analysis by. . 187 .Lunn, A. C., internal temperature of the earth 291 Lunquitz, E. E., gold sands 648 Lupton, N. T., analysis of water, cited 78 Lutecite 357 Lutecium 17,21,711 Luz, A., bauxite 499 Luzi, W., corrosion of diamond 325 formation of graphite 327 Lyell, C., precipitated calcium carbonate 549 Lyons, A. B., copper in lava 629 soils 508 M. Mabery, C. F., natural gas 714 petroleum 716, 717, 718, 719, 730 See also Robinson, A. E. Mabery, C. F., and Byerly, J. H., byerlite. . . 721 Mabery, C. F., and Hudson, E. J., petro- leum 716,717,718 Mabery, C. F., and Palm, O. H., Ohio petro- leum 717 Mabery, C. F., and Quayle, W. O., petro- leum 716,718 Mabery, C. F., and Smith, A. W., Lima oil. . 718 Mabery, C. F., and Takano, S., Japanese pe- troleum 716 MacAlister, D. A. See Hill and MacAlister. Macallum, A . B . , cited 127 MacBride, T. H., peat 745 McCaleb, J. F., cited 227 McCalley , H . , bauxite 497 McCallie, S. W.,iron ores 530,575 limestones 557 phosphate rock 528 waters of Georgia 63 McCaughey, W. J., solubility of gold 647 McClelland well, analysis 191 McConnell, W. , gases in coal 759 McCourt, W. E., and Parmelee, C. W., peat. 745 McCreath, A . S . , coal analyses 753 798 INDEX. Page. Mac6, , synthesis of anglesite 680 Macfarlane, W. See Ebaugh and Macfarlane. McGee, W J, bitumens 735 laterite 493 loess 509 Mcllheney, P. C., solvent of gold 646 McIntosh, D . See Eve, A. S. Mclvor, R. W. E., guano phosphates 520 maldonite 644 McKee, R. EL, mass of atmosphere 54 McKenzie, J. D., blairmorite 449 primary analcite 371 Mackie, W., allanite in granite 408 analyses of clays 507 analyses of sand 504 calcium fluoride as cement 539 on age of the earth 149 sandstones 541 Mackintosh, J. B. See Hidden and Mackin- tosh. Mackintoshite 712 Maclaren, J. N., gold and silver in sinter 207, 646 hot springs of New Zealand 213 Maclaren, M., laterite 494 Maclaurin, J. S., cited, on New Zealand spring waters 196, 200 mine waters 631 McLennan, J. C., and Kennedy, W. T., radio- activity 317 McNaim, W. H., apatite 523 Macomb deep well, analysis of water 193 Mactear, J., mercury ores 664 Madupite 447 Madupose 447 Maey , E . , silv er antimonide 650 Magdeburgose 435,436,437 Magma, temperature of 291-296 Magmatic assimilation 309, 310 Magmatic differentiation 307-313 Magmatic dissociation 299 Magmatic solutions 298-300 Magmatic stoping 310 Magmatic waters 634 Magnenat and Wooten, analyses by 747 Magnesioferrite 341 Magnesite 414,417,564 Magnesium, distribution 17 Magnetite 344-346 Magnetite basalt 346, 468 Magnetite spinellite 467 Magnetite syenite 469 Magnochromite 697 Hahanuddy River 105 Mahler, O., cal cite and dolomite 562, 564 Main, River, analysis of water 97 Majima, M. See Yamashita and Majima. MajoraDa, Q., diamond 323 Makin, C. J. S., analysis of sea water 123 Malacca, Straits of 125 Malachite 663,741 Malaguti, Durocher and Sarzeaud, silver in sea water 121 Malbot, H., and A. phosphorite 525 Malcolmson, J. W. See Kirk and Malcolm- son. Maldonite... 644 Page. Malheur Lake, analysis of water 161, 176 Malignose 445 Malkomesius, P., and Albert, R., Cassel brown 748 Mallard, E ., cristobalite 357 lead oxychlorides 680 Mallet, F. R., Indian corundum 339 laterite 493 lateritic manganese 534, 535 on langbeinite 224 Mallet, J. W., allanite 712 analysis by 207 gases from meteorites 287 silver in volcanic ash 271, 628 Maltha 720 Manchot, W., ilmenite 349 Mangandolomite 573 Manganese, distribution 18 in sea water 121 ores of 533-536 Manganese nodules 132, 133 Manganite 533 Manganosite 533 Manitoulin Island, analysis of water from 185 Manjak 721 Manley, J. J. See Gunther, R. T. Mann, P., alteration of titanite 350 constitution of pyroxenes 383 Manouschek, O. See Donath and Manou- schek. Manross, N. S., asphalt 721 synthesis of apatite 354 of lead ores 680,681,682 of scheelite 699 Marcano, V. See Muntz, A. Marcasite 334 Marck, W. von der, analysis of sandstone. . 538, 539 Marckwald, W., radioactivity 320 uranium ores 707 Marcus, E ., salt clay 222 Marcus, E ., and Biltz, W., Stassfurtsalt clay 222, 705 See also Biltz and Marcus. Marcusson, J., artificial petroleum 725 origin of petroleum 730 optical activity of petroleum 735 Mare Morto, analysis of water 125 Margarite 393 Margarodite 391 Margottet, J., reduction of silver sulphide — 649 synthesis of argentite 650 See also Hautefeuille and Margottet. Marialite 403-405,600 Maricose 464 Marienquelle, analysis of water 184 Marignac, C. de, synthesis of dolomite 559 Marigny, F. D., Algerian waters 66 synthesis of bomite 658 synthesis of galena 676 Marl 550 Marmora, Sea of, analysis of water 124 Marsden, R. S., artificial diamond 323 formation of crystalline silica 358 Marsh gas 729, 757, 758 Marshite 662 Marsilly, , analysis of peat 743 Martens, P. , Chilean thermal waters. ........ 252 INDEX, 799 Page. Martin, K. , phosphate rock 521 Martin, W. J. , platinum ores 700 Martinite 520 Masing, E., synthesis of anglesite 680 Mason, W. P., analysis by 191 Massicot 679 Massol, G. , helium in spring water 180 Matthews, E. B., classification of rocks 433 Matildite 653,654 Matlockite 680 Matson, G. C., phosphorite 527 Matteucci, R. V., volcanic ammonium chlo- ride 272 Matthews , W . D . , phosphatic nodules 525 Maucherite 692 Maumee River, analysis of water 70, 107 Maumen6, E . , manganese in sea weeds 121 Mauritz, B . , synthetic wollastonite 378 Mauzeliitel 691 Mawson, D., carnotite 710 Mawson, D., and Cooke, W. T., phosphates from guano 522 Mawson, D., and Laby, T. H., radioactivity of minerals 315 Maxwell, W., Hawaiian lavas and soils. 493, 494, 499 Mayengon , , artificial galena 677 sulphides formed in burning coal mine. . 689 Mayr, F. See Simmersbach and Mayr. Mayrhofer, J., cited 101 Mead, W. J., average composition of igneous rocks 24 bauxite 498 relative proportions of sedimentary rocks . 32 Meadows, T. C., and Brown, L., phosphorite . 526 Mecca, holy well at, analysis of water 197 Mediterranean Sea, analysis of water 124, 218 Medve Lake 172 Mehu, M. C., synthesis of cinnabar 665 Meigen, W., calcite and aragonite 551, 552 calcium carbonate as precipitant of metals 64 1 dolomite 560 laterite 494 Meionite 403-405, 601 Melanite 401 Melanochroite 681 Melanotekite 683 Meldrum, R., solubility of copper 656 Melilite 398-400 Mellite 741 Mellor, J. W., clay silicates 493,611 Melnikorite 334 Meionite 692 Melting points of minerals 292-296 Melvill, E. H. V., diamonds 325 Melville, W. H., analyses by 160, 186, 197, 450, 541, 546, 592, 606, 610, 668, 689 glaucophane rock 591 josephinite 330 Menaccanite 348 Mendel4ef, D., origin of petroleum 726 periodic classification 37 Mendipite 680 Meneghinite 678 Mennell, F. P., average composition of igne- ous rock 26 laterite. 494 Page. Merawoe River, analysis of water 105 Mercury, distribution 18 ores of 664-669 Merensky , H . , diamonds 325 Merian, A., constitution of pyroxenes 383 Merivale, W. , manjak 721 Merrill, F. J. H., gypsum 576 Merrill, G. P., analyses by 487 asbestos 384 cave gypsum 229 disintegration of rocks 481, 484, 487, 488, 489 gold in granite 332,642 meteorites 37,700 onyx marble 549 serpentine 384,602,603 Merrill, J. A., flint 543 Merrimac River, analysis of water 71 Merwin, H. E. See Hillebrand, Merwin, and Wright. Merz , A . R . , and Gardner, R . F . , analyses by . 233 Merz, C., water analysis 97 Mesitite 417,571 Mesolite 416 Metabrushite 520 Metachlorite 397 Metacinnabarite 664-669 Metahewettite 710 Metallic ores 626-712 Metamorphic rocks 583-625 Metastibnite 688,689 Meteorites, average composition 39-40 diamonds in 324 gases from 237 hydrocarbons in 728 Metzer, C., water analysis 101 Meunier, S., analysis by 185 bauxite 496 carbon in meteorite 728 composition of fossil plants 751 origin of petroleum 727 of platinum 703 planetary atmospheres 54 synthesis of anorthite 365 synthesis of brochantite 663 of chromite 344,697 ofenstatite 376 ofleucite 369 of nephelite 372 of olivine 390 of phcenicochroite 681 of spinel 342 of tridymite 359 tin in sinter 206,684 troilite 332 volcanic explosions 297 See also Daubr6e and Meunier. Meuse, River, analysis of water 94 Mexico, Gulf of 123 Meyer, E ., von, gases in coal 759 Meyer, J. , gases in coal 760 Meyer, O . , calcite and dolomite 564 Meyerhoffer, W. , phase rule 304 See also Van’t Hoff and Meyerhoffer. Miami River, analysis of water 78 Miagyrite 653,654 Miaskose 444, 450 800 INDEX. Page. Micas 391-396 Mica schist 614-617 Michael , P . , saussur ite gabbro 595 Michel, L., bismuth in molybdenite 698 synthesis of azurite 663 of lead ores 682 ofmelanite 402 of minium and plattnerite 679 of powellite 698 of rutile 351 oftitanite 350 of tungsten minerals 699 Michel-L6vv, A., magmatic differentiation. 310,311 minerals in sand 503 primary epidote 407 quantitative classification 433 scapol ite gabbro 596 Michel-L^vy, A., and Lacroix, A., envelop- ment of allanite 408 Michel-Ldvy, A., and Munier-Chalmas, E., chalcedony 357 Michigan, waters of 70 Michigan, Lake, analysis of water 69 Microcline 363-368 Micrometric analysis o f rocks 475 Micro-organisms in coal formation 763 Micropegmatite, as an eutectic 302 Microsommite 374 Middlemiss, C. S., Indian corundum 339 Miersite 655 Mikhailovsky, G. P., origin of naphtha 734 Miklucho-Maclay, M. von, occurrence of cas- siterite 353 Milch, L., glaucophaue rocks 591 quantitative classification 433 Milford, L. R., cited 186 Millar, C. C. H., phosphates 526 Millberg, C. See Lunge and Millberg. Mille Lacs Lake, analysis of water 76 Miller, A. M., phosphatic fossils 525 Miller, B. L., graphite 328 Miller, N. H. J., composition of rain water. 45, 50, 52 Miller, W. G., cobalt ores 694 corundum anorthosite 339 limestone 557 nickel in magnetite 345 Miller, W. G., magmatic assimilation 310 Millerite 692, 693, 694, 741 Mills, J . E . , geological work o f ants 485 Milosin 696 Mimetite 682 Minasragrite 707 Minervite 521,522 Minette 442 Minette (iron ore) 575 Mine waters 631-633 Mineral waters, classification 174-177, 180-181 Mingaye, J. C. H., analysis by 193 cave phosphates 522 mine water 631 platinum 703,704 vanadium in clay 705 Minium 679 Minnesota River, analysis of water 76 Minnetonka, Lake, analysis of water 76 Minor, J. C. See Penfield and Minor. Page. Minssen, H., and Tacke, B., solubility of calcium phosphate 519 Mirabilite 172, 227, 234, 247, 249, 251, 255 Miser, H. D., Arkansas diamonds 325 Mispickel 688 Missouri River, analyses of water 79 Missourite 447 Mississippi River, analyses of water 75 chlorine in 109 sedimentation in , , . . 505 silt 505 Mittagong chalybeate spring, analysis 193 Mitchell, , water analysis cited 169 Mitchellite 697 Mixite 662 Mizzonite 404 Moricke, W., gold in pitchstone 332, 642 Mofettes 262 Mohawkite 658 Mohawk River, organic matter in 107 Mohr, E. C. J., laterite 494 rivers of Java 105 Moissan, H., analyses of volcanic gases 268 carborundum in meteorite 326 graphite in native iron 328 melting point of corundum 336 metallic carbides 723 on diamond 323,324 origin o f petroleu m 727 origin of volcanic activity 281 volatility of metallic oxides 272, 273 See also Becquerel and Moissan. Moitessier, A . , artificial dolomite 561 Moldau River, analysis of water 98 Moldenhauer, F., analysis by 97 the Dead Sea 169 Molengraaf, G- A. F., cordierite vitrophyrite. 405 Molengraaf , P . F ., cassiterite 687 Molybdenite 335,698,741 Molybdenum, distribution 18 in mine water 631 ores of. . . 698 Molybdic ocher 698 Molybdophyllite 683 Molybdosodalite 373 Monazite 355,356,712 Monchiquite 450 Monchiquose 450 Monckton, G. F., mercury deposits 668 Monetite 520 Monke, H., and Beyschlag, F., origin of petroleum 730 Monmouthite 446 Mono Lake, analysis of water 160, 177 Monongahela River, analysis of water 78 Montesano Springs, analysis 183 Monticellite 389 Montmorillonite 415,500,611 Montroy dite 664 Monzonite 451,452 Monzonose 440,452,456 Moore, C. C., barytic sandstones 539 sandstones 541 Moore, E. J., bog iron ore - 530 Moore, E. S., siliceous oolites 544 Moore, G. E., analysis by 197 INDEX. 801 Page. Moore, R. B., and Kithil, K. L., uranium- vanadium ores 709 Moosehead Lake, analysis of water 71 Morawsky, T. See Schinnerer and Morawsky. Mordenite 416 Moreing, C. A., manganese ores 535 Morenosite 694 Morey, G. W., and Niggli, P., hydrothermal syntheses 586 Morley, E. W., variations in atmospheric oxygen 42,43 Morlot, A., von, sand calcites 537 synthesis of dolomite 560 Morozewicz, J., alteration of diorite 488 analysis by 467 artificial feldspars 365 composition of nephelite 372 formation of acmite 380 of augite 382 of corundum 337-339 of enstatite 377 of hematite 347 ofiolite 338,405 of magnetite 345 ofmelilite 399 of mica 394 of nephelite 373 of quartz and tridymite 361 of sillimanite 410 of spinel 338 lagoriolite 401 gravitative adjustment in magmas 312 syntheses of noselite, haiiynite, and soda- lite 375 of pyroxenes 377,379 solubility of alumina in magmas 305 Morrey, C. B., origin of petroleum 734 Morse, H. W., gases in fluorite 335 Morton, E. H. See Thorpe, T. E. Moses, A. J., mercury minerals 665 Moses, O. A., phosphate rock 526 Moses Lake, analysis of water 162, 176 Mosesite .?i.- - 664, 665 Moss, E . L . , on Arctic air 46 Mottramite 706 Moulton, F. R., internal temperature of the earth 291 Moureu, C., and Biquard, R., argon and helium in waters 180 radioactivity of waters 180 Moureu, C., and Lepape, A., helium in spring waters 319 Mourlot, A., vanadium in coal 706 Mrazec, L., petroleum 731 Mrazec, L., and Teisseyre, W., Roumanian salts 172 salt lakes of Roumania 234 Mrha, J . , kelyphite 403 Muchin, J., von, analyses by 701 Muck, F., constitution of coal 764 Muck, J., ozokerite 719 Muds, oceanic 512-514 Miigge, O., calcite and aragouite 551 Page. Miigge, O., fluorite as cement 539 forms of silica 360 lublinite 551 occurrence of perofskite 350 scapolite amphibolite 597 transition of quartz 360 Miilhauser, O., artificial graphite 326 Muller, E., water analysis 101 Muller, H., mine water 632 Muller, R., solubility of minerals 355, 478, 519 Muller , W . , artific ial magnetite 345 Muller, W. J. See Konigsberger and Muller. Muller, W. T., and Konigsberger, J., hydro- thermal syntheses 586 Muellerite 520 Munster, C. A., gold in sea water 121 Munster, bauxite. 496 Mumford, E. M., iron bacteria 530 Munroe, C. E., artificial hematite 347 Muntz, A., atmospheric transport of salt 52 bacterial decomposition of rocks 485 bromine in Chilean niter 256 nitrates in the Nile 106 origin of nitrates 257 Muntz, A., and Aubin, E., oxygen of the atmosphere 42 Muntz, A., and Lain6, E., nitrates in the at- mosphere 51 Muntz, A., and Marcano, V., black waters of South America 90 cave nitrates 253 nitric acid in rainfall 50 Murdoch, J. See Graton and Murdoch. Murdoch, J. A. W., atacamite ... 662 Murgoci, G. M., amphiboles 387 glaucophane schists 591 riebeckite rocks 389 Murray, Sir J., chemical reactions on ocean floor 131 oceanic carbonic acid 144 origin of manganese nodules 132 saline matter in rivers 112 total annual rainfall and run-off 58 volume of the ocean 22 Murray, J., and Irvine, R., ammonia in sea water 120 calcium carbonate in sea water 128 discharge of rivers 127 formation of siliceous ooze 515 maintenance of marine life 147 manganese nodules 132 re-solution of c oral rock 128 secretion of lithe salts by marine animals. 130 sediment in sea water 506 silica in sea water 120 Murray, J., and Renard, A. F., deep-sea de- posits 130, 131, 132, 134, 511 glauconite 135,516 oceanic sediments 511,512 phosphatie nodules 134, 524 solubility of silica 130 Murray, R. M., the Dead Sea 169 Muscovite 391-396,600 97270°— Bull. 616—16 51 802 INDEX. Page. Muskingum River, analysis of water 78 Muthmannite 644 N. Naab River, analysis of water 101 N acken , R . , synthesis of apatite 355 Nadorite 683 Nagyagite 676 Nahe, River, analysis of water 97 N ahnsen , M . , dolomite 569 N ant ier , A . , phosphorite 528 Nantokite 662 Napalite 719 Naphtenes 716 Naphthalene 717,718 Naschold, W. See Hauessermann and Naschold. Nasini, R., origin of boric acid 245 See also Perrone and Nasini. Nasini, R., and Anderlini, F., analysis by. . 184 Nasini, R., Anderlini, F., and Salvadori, R., fumarole gases 180, 245, 264 Nasini, R., and Levi, M. G., radioactivity of lava 315 Nasini, R., Levi, M. G., and Ageno, F., water analysis 188 Nason, F. L., Franklin zinc ores 676 iron ores 575 scapolite rocks 597 Nasonite 676,683 Nastukofl, A., cellulose 738 Natrolite . 416 Natron 162,239,247 Natron Lake, analysis of water 173 Natterer, K., ammonia in sea water 120 analyses of water 124, 169 carbonates in sea water 144 diffusion of salts 174 marine muds 515 potash in marine sediments 139 Natural gas 714,715 Naumannite 652,676 Navarro, F., native iron 328 Neagh, Lough, analysis of water 93, 107 Nebular hypothesis 139-140 Negro, Rio, analysis of water 91,107 Nelson, J. L., analysis by 385 Nelson River, analysis of water 87 Nelsonite 468 Nelsonose 468 N endtwich, , analysis by 746 Nentien, , antimony ores 689 Neodymium 18,711 Neon 18,41 N eosho River , analysis of water 81 Nephelite 371-373,600 Nephelite basalt 459 Nephelite rocks 443,446 Nephelite syenite 445 Nepouite 695 Nesquehonite 563 Nessler. See Petersen and Nessler. Neuberg, C., origin of petroleum 730 Neumann, P., diamonds in iron 324 Neuse River, analysis of water 72 Nevadite 434 Page. N evius , J. N . , tin deposits 685 Nevyanskite 700 Newberry, J. S., bog iron ore 530 cannel coal 751 origin of petroleum 733 ozokerite 719 Newbery, J. C., gold in iron ore 645 Newberyite 521 N ew land , D . H . , iron ores 469 N ewland , D . H. , and Leighton, H. , gypsum. . 232 Newsom, J. F. See Branner and Newsom. N ewton, W . , origin of nitrates 257 Newtonite 415,611 New Zealand geysers, analyses of waters. . . 196, 200 sinter from 207 Niccolite 652,692,694 Nichols, H. W., cave nitrates 253 corals and crinoids 555, 565 sand barites 538 N icholson , E . , analysis of water 105 Nickel, distribution 18 in ashes of sea weed 121 ores of 691-696 Nickel-iron, native 330,331 N icolardot , P . , hydroxides of iron 531 Niederstadt, K., Meigen’s reaction 552 Niggli, P. , gas mineralizers 290 hydrothermal syntheses 586 metamorphic rock series 588 See also Johnston and Niggli; Morey and Niggli; Schlaeppfer and Niggli. Nile River, analysis of mud 505 analyses of water 106, 107 sedimentation in 115, 505, 506 Niobium. See Columbium. Nishihara, G. S., secondary enrichment 662 Niton 18,315 Nitrate deposits 253-259 Nitric acid in rainfall 50 N itrogen , distribution 18 in sea water 120 proportions in the atmosphere 41 volcanic 272 Nitrogen bases in petroleum 718 Nitroglauberite 254,255 Nitze, H. B. C., iron ores 575 monazite 356,712 Nivenite 707,708,712 Nivoit, E ., phosphate rock 519 Nocerite 271 Noeggerath, J. J., pyromorphite in slag 682 Noellner, C., origin of nitrates 257 Noelting, J., zinc blende 669 Noir, Lac 95 Noll, J.C., cited 97 Nontronite 491 Nordenskiold, A . E . , carbon in meteorite .... 728 native iron in Greenland 328 uranium in coal 710 Nordenskioldine 684,686 N ordmarkite 439 Nordmarkose 439,445 Norite 462 North Platte River, analysis of water 79 Northupite 247 Norton, J. H., cited 80 INDEX. 803 Page. Norzi, G., see Porlezza and Worzi. Nosean. See Noselite. Nosean sanidinite 448 Noselite 374-375 Noumeite 695 Novaculite 542,544 Noyes, W. A., analyses by . . . . 69, 70, 76, 87, 189, 487 Nutter, E. H., and Barber, W. B., glauco- phane rocks 591 Nutting, P. G., uranium and solar spectrum. 319 N yholm , E . T . See Ramsay and N yholm . O. Oak Orchard acid spring, analysis 198 Obalski, J., uranium in pegmatite 710 Obsidian 435 Occlusion of gases in rocks 274-285 Ocean, age of 148-150 composition of 23 elements in 119-122 gases in 141-147 influence of living organisms on 147 the primeval 140 volume of 22 Ocean water, carbonates in 128-130 changes in composition due to freezing. . . 126 concentration of 122-126 density and salinity of 122-126 Oceanic salts, composition of 23,122-128 volume of 24 Oceanic sediments 130-138,511-515 Ochers as spring deposits 204, 205 Ochrolite 683 Ochsenius, C., average composition of igneous rock 26 cited, on Stassfurt salts 220, 221 on Great Salt Lake 155 origin of alkaline carbonates 242 of borates 252 of petroleum 731 of salt beds 220-221 saltpeter deposits 254, 258 Ocmulgee River, analysis of water 73 Oconee River, analysis of water 73 Octahedrite 350-352 Oden, S., organic matter of soils : 108 Oder, River, analysis of water 102 Oebbeke, K., glaucophane rocks 388,591 Oehmichen, H., chalcanthite 663 Ogden River, analyses of water 156 Oil shale 740 Ojo Caliente, analysis of water 191 Okechobee, Lake, analysis of water 73 Okenite 416 Oklahoma, river waters 80 Oldham, R. D., laterite 493 Old Wives Lake, analysis of water 163,174 Olefines 716 Olette Springs, analysis 195 Oligoclase 364 Olivenite 662 P Olivier, V., Chilian nitrates 254 Olivine 389-391 Om, River, analysis of water 104 Omak Lake, analysis of water 162, 176 Omeose 437 Page. Omphacite 598,599 Onega, Lake, analysis of water 104 Onofrite 664 Onyx marble 549 Oolite, calcareous 550, 553 Oolite, siliceous 544 Oolitic sand 550,558 Oostanaula River, analysis of water 74 Opal 357-363 Ophicalcite 622 Ophiolite 603 Ordonez, E . , petroleum 727 Organic matter in rock decomposition 483-484 Organic matter in waters 107, 210 Orpiment 688,689 Orthite 406 Orthoclase 363-368,600 Orthogneiss 618 Ortlieb, J., ciplyte 523 Orton, E., dissemination of petroleum 735 origin of petroleum 730 spore cases in coal 763 Osage River, analysis of water 81 Osann , A. , classification of igneous rocks 425 holmquistite 388 rock diagrams 475 Osmium 18,700-704 Osteolite 520 Oswegatchie River , analysis of water 70 Ottawa River, analysis of water 70 Otten, F. K., river waters 166 Ottrelite 393,395,612 Ottrelite schist 613,614 Outwater, R. , analysis of water 72 Ovenstone 606 Ovitz,F. K. See Porter and Ovitz. Owens Lake, analysis of water 160, 177 soda from 239 Owens River, analysis of water 160 Owyhee River, analysis of water 85 Oxygen, concentrated by solution 49 distribution 18 proportions in the atmosphere 42 solubility in salt water 143 Ozokerite ' 719,734 Ozone in atmosphere 43 P. Pack, J. W., gold in sea water 122 Packard , R . L. , analysis by 487 Pagenstecher, J. S. F., water analyses 97 Pahua Spring, analysis 183 Paigeite 684 Palache, C. , crossite 388 See also Jaggar and Palache; Lawson and Palache; Ransome and Palache. Palic Lake, analysis of water 176 Palladium 18,700-704 Palladium gold 644, 700, 703 Palm, O. H. See Mabery and Palm. Palmer, A. W., chlorine in river waters 109 Palmer, C., alkali determinations 68 analyses by 70, 71, 72, 73, 74, 75, 76, 78, 79, 82 composition of crinoids 565 diatoms in peat 211 804 INDEX. Page. Palmer, C., interpretation of water analyses. . 63 sulphides of nickel 692 Palmer, C., and Bastin, E. S., precipitation of silver and gold by ores . . 648, 651, 652 Palmerite 522 Palmier ite 271,681 Panebianco, G., Meigen’s reaction 552 Pandermite 248 Pantanelli, D . , origin of petroleum 730 Papagayos , Rio de los, analysis of water 92 Papa vasiliu, S. A., emery 340 Pappe, A., and Richmond, H. D., water analysis 173 salt 231 Paraffin series 714 Paragonite 392,395,600 Paragneiss 618 Paralaurionite 680 Paramo de Ruiz, hot spring, analysis 199 Parana, River, analysis of water 91 Pargasite 384 Parinacochas, Lake, analysis of water 164, 174 Park, J., mercury ores 668 Parker, E . G. , absorption by soils 501 Parker, H. N., and Bailey, E. H. S., waters of Kansas 68 Parmelee, C. W. See McCourt and Parmelee. Parmentier, F., alumina in mineral waters. . 496 synthesis of quartz and tridymite 359 Parr , S . W . , classification of coals 756 Parry , J . , gases in iron 287 Par sons , A . L . , gypsum 232 peat 745 Paschen, F., heat of radium 314 Pascoite 707 Passarge, S., laterite 493 Patronite 706 Patten, H. E., and Waggaman, W. H., ab- sorption in soils 501 Patton, H. B., formation of tourmaline 413 Pay en , A . , Tuscan f umaroles 245 Pearce, R. , solvent of gold 647 uraninite 707 Pearceite 653 Pearl River, analysis of water 74 Peat 742-745 cupriferous 657 diatoms in 211 Pecher, F., cited 101 Peckham, S. F., albertite 720 origin of petroleum 733 petroleum 718 Peckham, S. F. and H. E., sulphur in petro- leum Ti 718 Pecos River, analysis of water 82 Pectolite 378,416 Peedee River, analysis of water 73 Peganite 520 Pegmatite 434 Peile , W . , bauxite 497 Peipus, Lake, analysis of water 104 Pekatjangan, River, analysis of water 105 Pelabon, G. , jamesonite and zinkenite 678 Pelican Lake, analysis of water 162, 176 Pelikan, A., analcite phonolite 371 Page. Pellini, G., and Quercigh, E., tellurides of gold 645 tellurides of silver 653 Pemberton, H., and Tucker, G. P., water analyses 163 Pencatite 570 Penfield, S. L., analyses by 712 caesium beryl 413 sulphohalite 247 See also Dana and Penfield; Genth and Penfield; Iddings and Penfield; Wells and Penfield. Penfield, S. L., and Foote, H. W., composi- tion of tourmaline. 413 magnesia in ilmenite 348 Penfield, S. L., and Forbes, E. H., fayalite in granite 391 Penfield, S. L.,and Ford, W. E., sand calcite.. 537 Penfield, S. L., and Jamieson, G. S., tychite. 247 Penfield, S. L., and Minor, J. C., formula of topaz 408 Penfield, S. L., and Pratt, J. EL, formula of staurolite 411 Penfield, S. L., and Sperry, F. L., chlorite pseudomorphs 402 Penfield, S. L., and Stanley, F. C., composi- tion of hornblende 384,385,387 Penfieldite 680 Penhale, M. , chromite deposits 697 Penninite 397 Penrose, R. A. F., alterations of oredeposits. 638 causes of ore shoots 638 Chilean nitrates 225, 258 iron ore from glauconite 530, 573 manganese ores 535 phosphate rock 519, 526, 528 tin deposits 685 Pentlandite 692,693 Perchlorates in Chilean niter 256 Percy, J., coal analysis 753 copper in peat 657 Percylite 680 Periclase 570,623 Peridot 380 Peridotite 465,466 Periodic classification of theelements 35-30 Perofskite 340 Perofskite-apatite-magnetite 468 Perrey, A. See Hautefeuille and Perrey. Perrone, E . , origin of borates 245 Perrot, F. L. See Jaquerod and Perrot. Peter, R., matter extracted from soil by plants 484 cited 183 Petermann, A., and Graftiau, J., cited 45 Petersen, T . , bauxite 496 nickel in magnetite 345 Petersen and N essler , analyses of peat 742 Petersen and Schodler, analyses of wood 730 Petersson, W. , analysis by 467 Petrasch K. , f usion of mineral mixtures 306 Petrenko, G. I., silver antimonide 650 Petroleum 713-737 Petterson, A . , heat of radium, 314 Pettersson, O . , on brine from melting ice 126 INDEX. 805 Page. Pettersson, O., and Sond<§n, K., on air from sea water 49, 142 Petzite 644,645 Pfaff , F. W. , dolomitization 562, 563 Pfeiffer, E . , cited on Stassfurt salts 221, 222 Pfordten, O. von der. See Konig, T. Phacelite 371 Phalen, W. C. , celestite 579 unakite 598, 599 Pharmacolite 691 Pharmacosiderite 691 Phenol, in petroleum 718 Philip, R. S. See Gibb and Philip. Philippi, E . , carbon dioxide and climate 48 dolomite 563 Phillips, F. C. , formation of marsh gas 729 natural gas 715 petroleum in fossils 731 Phillips, J. A., action of sea water on rocks 569 desert sand 503 gold on cinnabar 646 mercury deposits 668 mine waters 631 sandstone 541 Phillips, W. B., iron ores 575 petroleum 717 phosphorite 526 T erlingua mines 665 Phillips, W. B . , and Hancock, D . , bauxite — 497 Phillipsite 416,417 Phipson, T . L. , primitive atmosphere 55 Phlegrosse 439 Phlogopite 392-396 Phoenicochroite 681 Phonolite 444 Phosgenite 679 Phosphate rock 519-528 Phosphatic nodules 134-135 Phosphorite 523-528 Phosphorus , distribution 19 in sea water 120 Phosphosiderite 520 Pbyllite 611,613 Phytostearin 735 Pichard, P., solubility of minerals 478 Pickeringite 249 Picotite 343 Picrite 463,464 Picromerite 223 Pictet, A., and Ramseyer, L., experiments on coal 764 Piedmontite 406-408 Pierre, I., salts in rainfall 52 Pigeon River, analysis of water 70 Pilotti,C., phosphates 525 Pimelite 695 Pinite 406 Pinnoite 225,250 Pinnow, J. See Will and P innow. Pintadoite 710 Piolti, G., precipitation of zinc by calcite 673 synthesis of anglesite 680 Pirovaroff, J., chlorine in rain 52 Pirsson, L. V., cassiterite in hematite 685 crystallization of magmas 311 Page. Pirsson, L. W., primary analcite 370, 449 See also Weed and Pirsson. Pirssonite 247 Pisani, F., analysis of spinel 342 See also Saemann and Pisani. Pisolite 552 Pissis, A., nitrates 254 Pistomesite 571 Pitchblende 707 Pitch coal 719,720,746 Piutti, A., helium in minerals 319 Plagionite 678 Planch^ite 663 Planetesimal hypothesis 56, 140, 286 Plata, River, analysis of water 91, 107 Platania, G., temperatures at Etna 296 Platiniridium 702 Platinum, distribution 19 in igneous rocks 332 ores of 700-704 Platte River, analyses of water 61, 79 Plattensee, analysis of water 102 Plattnerite 679 Plauchud, E., reduction of sulphates by mi- crobes 577 Playa Lakes 237,509 Playfair, L., colliery gases 760 Pleochroic halos 320 Pleonaste 343 Plombieres, action of hot waters at, on brick. 210 analyses of waters cited 210 Plumbogummite 681 Plumbojarosite 680,681,704 Plummer, G. W., pyrite and marcasite 334 Podolite 355 Poeschl, V., silicate fusions 306 Pogue, J. E., sand barites 537,538 Pollard, W., uranium and vanaaiumin rocks. 705 See also Clough and Pollard. Polianite 533 Polonium 12,314 Polyargyrite 653,654 Polybasite 653 Polydymite 692,704 Polyhalite 223 Polylithionite 392 Polymethylenes 716 Pomeroy, Ohio, brine 182 Ponte, G. G., Etna 265 Ponteil, O. du, water analysis 200 Poole, H. H., radioactivity 315 Popocatepetl, water from 200 Popoff, L., gas from river mud 729 Popoff, S. P. See Vernadsky and Popoff. Popovici, Saligny and Georgesco, water analysis 172 Popp, O., boron nitride 245 urao 238 water analysis 106 Porcher, S., electrum 644 Porlezza, C., and Norzi, G., argon and helium infumaroles 268 Porter, F. B. See Bailey, E. H. S. Porter, H. C., and Ovitz, F. K., gases in coal. 760 Porter, J. L., analysis of water 75 806 INDEX. Page. Porter, J. T., fuller’s earth 508 Posepny, F., atmospheric transport of salt... 52 lateral secretion 627 heavy metals in waters 631, 634 ore deposits 626 Posewitz, T., asphalt and petroleum 721 Posnjak, E., experiments on copper ores 651 Potaro River, analysis of water 90 Potassium, distribution 19 in seaweed 139 proportion of, in ocean 138, 139 Potassium nitrate. See Saltpeter. Potassium salts, absorption by clays 211 Potomac River, analysis of water 72 Potonie, H. , origin of coal 740 origin of petroleum 734 Pouget, I., artificial pyrargyrite 654 Powder River, analysis of water cited 85 Powellite 698 Power, F. D., nickel ores 695 Pozzi-Escot, E., analysis by 164 Pozzuoli, analysis of solfatara water 199 Praseodymium 19,711 Praseolite 406 Pratt, J. H., chromite deposits 344,697 corundum 339-340 gaylussite, northupite, pirssonite 247 occurrence of spinel 343 origin of talc 415 talc 605 See also Hidden and Pratt; Penfield and Pratt. Pratt, J. H., and Lewis, J. V., chromite de- posits 697 Pratt, J. H., and Sterrett, D. B., tin deposits. 687 Pratt, N. A., phosphate rock 527 Precht, H., cited, on Stassfurt salts 221 on langbeinite 223 Precht, H., and Wittjen, B., kieserite 227 Precht, J. , heat of radium 314 See also Runge and Precht. Predazzite 570 Prehnite 601 Prehniterock 624 Preiswerk, H., sodalite trachyte 375 Pressure and chemical change 291 Prestwich, J., water in volcanism 284 Pretoria salt lake, analysis of water 173, 176 Price, T., water analysis cited 83, 199 Priceite 248 Priestley, J., gases in rocks 274 Primero, Rio, analysis of water 92 Pring, J. N., ozone in atmosphere 43 Pring, J. N., and Hutton, R. S., synthetic hydrocarbons 724 See also Hayhurst and Pring. Prior, G. T., dundasite 679 riebeckite rocks 389 teallite, etc 684 See also Hussak and Prior. Prior, G. T., and Spencer, L. J., cerargyrite group 655 Prismatine 381,393 Priwoznik, E., native iron 331 Prochlorite 397,600 Prost, E. See Spring, W. Page. Proustite 653,654 Prowersose 442 Przibylla, C., formation of carnallite 225 Pseudoboleite 680 Pseudobrookite 349 Pseudogay lussit e 158 Pseudoleucite 371 Pseudonephelite 372 Pseudowollastonite 378 Psilomelane 533,534 Psittacinite 682 Pteropod ooze 131,512 Ptilolite 416 Pucherite 706 Puiggari, M., cited 91 Pulaskose 439,450 Pulgar, P. del. See Calderon, C. S., etc. Pumpelly, R., native copper 656 loess 509 sedimentation 511 Purdue, A. H., phosphate rock 526 Purington, C. W., Uralian platinum 702 Pyramid Lake, analysis of water 158, 176 Pyrargyrite 653,654 Pyrite 332-335,741 Pyrocatechin 765 Pyrochroite 533 Pyrolusite 533,534 Pyromorphite 682 Pyrope 400 Pyrophanite 348 Pyrophyllite 415, 493, 605, 611 Pyrostilpnite 653 Pyroxene 376-383 Pyroxenite 464 Pyrrhotite 332-335 Q. Quadrat, B., analysis of spinel 342 Quantitative classification of rocks 425-433 Quartz 357-363 gaseous inclusions in 274 melting point 293 volatility of 273 Quartz-alunite rock 497 Quartz basalt 458 Quartz-diaspore rock 497 Quartz diorite 453 Quartz monzonite 452 Quartz porphyry 434,436 Quartz trachyte 434 Quartzine 357 Quartzite 606-608 Quayle, W. O. See Mabery and Quayle. Quensel, P. D., formation of quartz and tridymite 293,359 Quercigh, E. See Pellini and Quercigh. Quercylite 523 Quincy mine, water from 185 Quinton, R., ocean water 119 Quisqueite 706,746 R. Raben, E., nitrogen and silica in sea water. . 120 Radioactivity 313-320,709 Radiolarian ooze 131, 512, 513 INDEX. 807 Page. Radiothorium 12,315 Radium 19,314 emanation 18,315 in coal 741 in sea water 122 in springs 215 Radominsky, F., synthesis of monazite and xenotime 355 Ragsky, F., analysis by 193 Rainfall 49-52 Raken, M. See Cohen, E. Rakusin, M., petroleum 735 Ramage, H. See Hartley, W. N. Ramirite 706 Rammelsberg, C., composition of tourmaline. 413 Rammelsbergite 692 Ramsay, Sir W., composition of the atmos- phere 41 sedimentation 506 See also Rayleigh and Ramsay. Ramsay, W., and Travers, M. W., argon and helium in minerals 274, 275 Ramsay, W. (of Helsingfors), and Illiacus, A., monazite in pegmatite 356 Ramsay, W., and Nyholm, E. T., cancrinite syenite 375 Ramsay and Hunter, sintering of silica 363 Ramseyer, L. See Pictet and Ramseyer. Rangeley Lake, analysis of water 71 Rankin, G. A. See Shepherd and Rankin. Ransome, F. L., alunite and diaspore 259,497 chert 543 enrichment of sulphides 639 glaucophane schist 591 lawsonite 411 See also Hillebrand and Ransome. Ransome, F. L., and Palache, C., lawsonite. . 411 Raritan River, analysis of water 71 Rastall, R. H. See Hatch and Rastall. Rath, G. vom, anorthite in marble 622 cristobalite 357 sublimed silicates 273 sulphur deposits 578 Rathite 678 Ray, J. C., Butte ores 662 Rayleigh, Lord, argon in springs 180 hydrogen in atmosphere 44 Rayleigh, Lord, and Ramsay, W., argon in springs 180 Raymond, R . W. , uintaite 720 Read, T . T . , copper sulphide 660 phase rule 304 platinum 704 Read, W. T., analysis by 73 Reade, T. M., chemical denudation 112, 114, 117 Realgar 270,688,689 Recknagel , R . , origin of tin deposits 686 Rectorite 611 Red clay, oceanic 131,512-514,629 Red Lake, analysis of water 169, 174 Red River (Louisiana), analysis of water 81 Red River of the N orth , analyses of water 87 Red Sea, analyses of water 125 Redingtonite 696 Redlich, K. A., and Cornu, F., talc deposits. . . 605 Redwood, B . , formation of petroleum 725, 732 Page. Reese, C. L., solubility of calcium phosphate.. 519 Refdanskite 695 Regen, River, analysis of water 101 Regnault, V., oxygen of the atmosphere 42 Reich , A . , synthesis of sillimanite 410 of topaz 408 See also Stutzer, A. Reich, F . , electrical activity in ore bodies 640 Reichardt, E . , analysis of bittern 233 Reichardtite 223 Reichert, F. , Argentine borates 250 Reid , C . , and Scrivenor , J . B . , cassiterite 684 Reid, J. A., mine water 631 Reid , W . F . , Argentine nitrates 256 Reinders, G., bog iron ore 530,532 Reiner, P., tourmaline 413 Reindl, J., cited 90 Reinitzer, B., trona 240 Reiset, J., carbon dioxide in air 45 Reiter, H . H . , fusion of mineral mixtures 306 Reitinger, J. See Hussak and Reitinger. Remingtonite 694 Renard, A. F., phthanite 542 phyllites 614 See also Murray, J. Renard, A. F., and Cornet, J., phosphorite 525 Renault, B . , cannel coal 751 peat 744 micro-organisms in coal 763 See also Bertrand and Renault. Renner, O., baeumlerite 225 Rennie, E . H . , vanadium in clay 705 Resins 741 Republican River, analysis of water 80 Retgers, J. W., constitution of pyroxenes 383 minerals in sand 503 Reuter, M . See Treadwell, F. P . Reyer , E . , volcanism 285 Reyes, Rio de los , analysis of water 92 Rezbanyite 678 Rheineck, H., composition of tourmaline 413 Rhine, River, analyses of silt 505 analyses of water 97, 107 Rhodium 19,700-704 Rhodium gold 700 Rhodoehrosite 571 Rhodonite 379 Rhodose 468 Rhodusite 388 Rhoenite 388 Rhone, River, analysis of water 94 Rhyolite 433-438 fusibility 299 Riban, J., synthesis of cerusite 679 Ricciardi , L . , vanadium in lava 705 Richards, Ellen S., chlorine maps 51 Richards, R. H. See Day and Richards. Richards, R. W. See Gale and Richards. Richardson, C., asphalt 721,722 grahamite 722 Richardson, C., and Wallace, E. C., Texas petroleum 717 Richardson, G . B . , natural gas 714 sulphur deposits 578 tin deposits 686 waters of Utah 155 808 INDEX. Page. Richardson, T., barytic deposit 579 Richmond, H. D. See Pappe, A. Richterite 384 Richthofen, F., loess 509 Rickard, E . , tin deposits 686 Rickard, F., tungsten ores 699 Rickard, T . A . , precipitation of silver 649 solution and deposition of gold 647, 648 Rickardite 658 Ricketts, L. C. , cited 163 Riebeckite 388,389 Riedel, O., cited 221 Rieke, R., melting points of silicates 292 See also Endell and Rieke. Riemann, C., Stassfurt salts 221 Ries, H., alteration of pyroxenes 383 clays 492,508 limestones 557 peat 745 zincite 672 Riess, E. R., eclogite 598 Rigaud, F., origin of coal and petroleum 727 Riggs, R. B., analyses by 453, 507, 508, 510, 573, 596, 608, 619 Riley, E., titanium in clays 500 Rimann, E., magmatic sphalerite 671 Rinne, F., koenenite 225 reactivity of quartz 363 Rinne, F., and Kolb, R., Stassfurt salts 225 Rinneite 225 Rio Grande, analysis of water 82 Rising, W. B. See. Le Conte and Rising. Risler and Walter, Lac Ldman 94 Ritom, Lac, analysis of water 95 Ritter, A., nature of earth’s interior 57 Rivas, S., cited 91 Roanoke River, analysis of water 72 Roberts, J. See Anderson and Roberts. Roberts, M. G., analyses by 69, 70, 71, 72, 73, 78 Roberts- Austen, W. C., melting points of minerals 292,293 Robertson, J. D., heavy metals in rocks. . . 628, 674 precipitated zinc sulphide 671 zinc deposits 674, 675 Robinson, A. C., and Mabery, 0. F., analysis by 185 Robinson, F. C., analyses of water 71 phosphoric acid in beryl 414 Rockbridge Alum Spring, analysis 198 Rock River (Illinois), analysis of water 77 Rock River (Minnesota), analysis of water. . 76 Rodzyanko, A., cited 108 Roeblingite 683 Roepperite 389 Roesler, H., kaolinization 492 ltoessler, F., synthesis of argentite 650 of matildite 654 of galena and clausthalite 677 Rossler, H., platinum in silver bullion 704 Rottisite 695 Rofe, J., cannel coal 751 Rogers, A. F., alterations of copper 657 corundum syenite 339 dahllite, etc 523 riebeckite rocks 389 Page. Rogers, A. F., secondary enrichment 662 synthesis of covellite 659 Rogers, W. B., and R. E., solubility of min- erals.. 478 Rogue River, analysis of water 86 Rohland, P., plasticity of clays 502 Roloff, M., cited 301 Romburgh, P. van, analysis by 197 Romeite .-. 691 Romer, E. von, cited 149 Roncegno, analysis of water from 188 Rondet, J., sulphosalts of lead 678 Roozeboom, H. W. B., phase rule 304 Roscoe, H. E., mottramite 706 Roscoelite 391,707 Rose, G., fusion of limestone 556 synthesis of tridymite 359 uralitization 590 Rose, T. K., alloys of gold and tellurium 645 Roselite 694 R oseland ose 468 Rosen, F., alteration of dolomite 571 Rosenbach, O., volcanic nitrogen 272 Rosenbusch, II., chloritic substance 600 classification of igneous rocks 425, 472 epidotization . 597 garnet and prehnite rock 624 glaucophane rocks 388 gneiss 618 order of deposition of minerals 307 succession of minerals in igneous rocks . . 472 venanzite 459 See also Hunter and Rosenbusch. Rosenbuschite 383 Rosenlecher, R., mercury deposits 669 Rosiwal, A., physical analysis of rocks 475 Ross, O. C. D., origin of petroleum 728 Ross, W. S., nitrates 254 Rdsza, M., Stassfurt salts 221 Rossel, H., carbide theory of volcanisra 281 Roth, J., predazzite 570 Rothpletz, A., oolitic sand 550 Roumania, salt lakes of 172 Rousseau, G., artificial diamond 324 Roux, B., water analysis 168 Rowland ite 712 Rubidium, distribution 19,28 in feldspar 365 in sea water 121 Ruer, R. See Levin and Ruer. Ruff, O., iron hydroxides 531 Rumbold, W. R., tin deposits 685, 687 Rumpfite 397 Runge, C., and Precht, J., heat of radium . . . 314 Ruppin, E., ocean water 139, 145 Russ, F., aluminum hydroxides 498 Russell, I. C., adobe soil 509 calcareous tufa 549 disintegration of rocks 490 gypsum 228 Lake Lahontan 158 playa lakes 237 residual clays 50S,559 Russian River (California), analysis of water. 83 Rust. See Fischer and Rust. INDEX, 809 Page. Ruszanda, Lake, analysis of water 172,177 Ruthenium 19,700-704 Rutherford, E., age of minerals 318 radioactivity 317 See also Joly and Rutherford. Rutherford, E., and Barnes, E. T., heat of radium 314 Rutile 350-352 Rutile-nelsonite 468 Rutley, F., novaculite 542 Ryba, F., chromite deposit 697 Rzehak, A., mercury deposits 669 S. Saale, River, analysis of water 99 Sabatier, P., and Senderens, J. B., synthetic hydrocarbons 724 Sacc, F., niter in Bolivia 256 Sachs, A., kleinite 665 Sachsse, R., water analysis 168 Sacramento River, analysis of water 83 Sadtler, S. P., distillation of linseed oil 725 natural gas 715 Saemann, L., and Pisani, F., alteration of cancrinite 375 Safflorite * 692 Safford, J. M., phosphorite 526 Sahlbom, N., analysis by 445 Saint-Gilles, L. P. de. See Hautefeuille and Saint-Giiles. St. Clair, S., Sudbury ores 693 St. Lawrence River, analyses of water 69 flow of 71 Saladillo, Rio, analysis of water 92, 164, 173 Salic minerals 426 Salinas River, analysis of water 83 Saline River, analysis oi water 80 Salisbury, J. H., the Dead Sea 169 Salisbury, R. D., mineral matter in the sea. . 127 See also Chamberlin and Salisbury. Salite 379 Salomon, W., occurrence of spinel 342 scapolite 404 Salsomaggiore, water of, analysis 184 Salt 224,228-231,249,274 Salt beds, origin 217-221 Saltet, R. H., and Stockvis, C. S., cited Ill Saltpeter 256 Salt River, analysis of water 82 Saluda River, analysis of water 73 Salvadori, R., synthetic hydrocarbons 723 See also Nasini, R. Samarium 19,711 Samarskite 707,710 Sambhar Salt Lake 150, 173 Samsonite 653 Sand 502-504 Sandberger, F., analyses by 196 lateral secretion 627 platinum in limonite 703 serpentine 602 Sandstone 537-542 average composition 28 Sandstone reefs 538 Sanford, S., precipitated calcium carbonate. . 549 San Gabriel River, analysis of water 83 Page. San Joaquin River, analysis of water 83 San Rom&n, F. J., water analysis 164 Santa Ana River, analysis of water 83 Santa Clara River, analysis of water, cited. . . 83 Santa Maria River, analysis of water 83 Santa Ynez River, analysis of water 83 Saponite 415 Sapper, K., volcanoes of Java 283 Sapropel 734,740 Sarasin, E. See Friedel and Sarasin. Saratoga waters, analyses 186 Sardeson, F. W. See Hall and Sardeson. Sarkinite 691 Sartorite 678 Sartorius von Waltershausen, and Lasaulx, A. von, Etna 265 Saskatchewan River system 87 Sassolite 243 Sauer, A., alteration of leucite to analcite 371 graphitoid 754 kryptotile 393,611 Saussurite 407,595 Savage, T. E., peat 745 Savannah River, analysis of water 73 Savu-Savu Spring, analysis of 185 Saxonite 463,465 Saytzefl, A., Uralian platinum 702 Scacchi, A., fluorite on lavas 335 leucite pseudomorphs 371 sublimed silicates 273 Vesuvian sublimates 261, 271 Scandium 19,711 Scapolite 403-405,596 Scapolite rocks 596, 597 Scarpa, O., radioactivity of lava 315 Schafarzik, F., the Medve Lake 172 Scbafhautl, P., snythesis of quartz 357 Schaller, W. T., analyses by 614 barbierite 364 bisbeeite and shattuckite 663 bismuth ocher 690 dahllite and podolite 355 dumortierite 412 hulsite and paigeite 684 molybdic ocher 698 nephelite 372 tourmaline 413 tremolite 387 vanadium minerals 707 warrenite 678 Schaller, W. T., and Hillebrand, W. F., lawsonite 411 See also Hillebrand and Schaller; Hess and Schaller. Schapbachite 653,678 Schardt, H., subterranean erosion 210 Scharizer, R., composition of tourmaline 413 constitution of hornblende 386 Scheelite 699 Scheerer, T., formation of dolomite 561 of magnesian carbonates 565 Scheererite 719 Scheflerite 378 Schenck, A., chloritization 600 copper ores 659 epidotization 407, 597, 598, 599 810 INDEX. Page. Schering, H. G., loess 509 Schertel, A., melting points of minerals 291 See also Stelzner and Schertel. Schertel, A., and Erhard, T., cited 291 Schertelite 520 Schick endantz, Fr, cited 236 Schiebe, O., gold in olivine rock 642 Schilling, J., distribution of thorium 711 Schinnerer, L., and Morawsky, T., pyroca- techin from lignite 765 Schirmerite 653,678 Schlaepffer, M., and Niggli, P., hydrothermal syntheses 586 Schlagintweit, H. von, Tibetan borax 250 Schleimer , H . , silicate fusions 306 Schliersee, analysis of water 96 Schlosing, C., sedimentation 506 Schloesing, T., ammonia in atmosphere 51 ammonia in sea water 120 analyses of sea water 123, 124 oceanic carbonic acid 143 plasticity of clays 502 solubility of calcium carbonate 128 solubility of calcium phosphate 519 tropical soils 499 Schlundt, H., radioactivity of waters 215 Schlundt, EL, and Moore, It. B., radioactivity of waters 215 Schmelck, L., analyses by 124,442 calcareous organisms 566 marine clays 139 marine muds 515 Schmidt, C., chamosite 575 sericitic rocks 593 Schmidt, C. (Dorpat), water analyses 104, 123, 124, 125, 166, 169, 171, 244 fumaroles of Monte Cerboli 244 Schmidt, R. E. See Lunge, G. Schmidt, W. B., action of sulphurous acid on rocks 483 Schmitz, E. J., copper in fossil wood 657 Schmutz, K. B., artificial scapolite rock 404 formation of tridymite 358 fusion of mineral mixtures 306 Schnarrenberger, C., analysis by 624 Schneeberger, P. See Gilpin and Schnee- berger. Schneebergite 691 Schneider, E. A., analyses by 207, 464, 487, 541, 544, 608 augite-andesite 487 See also Barus, C.; Clarke and Schneider. Schneider, J., water analysis 172 Schneider, K., origin of perofskite 350 Schneider, O., rinneite 225 Schneider, R., cubanite 658 precipitation of silver sulphide 651 synthesis of emplectite 661 of wittichenite 661 of greenoclcite 670 of matildite 654 Schodler. See Petersen and Schodler. Schoeller, water analyses 91 Schoenite 223 Schorlomite 401 Schrauf, A., kelyphite 402 mercury ores 668, 669 Page. Schrauf, A., mine waters 631 serpentine from garnet 603 Schreibersite 329 Schreiner, O., and Failyer, G. H., absorbent power of soils 501 See also Kahlenberg, L. Schreiner, O., and Shorey, E. C., organic mat- ter of soils 108 Schroter. See Friih and Schroter. Schrotterite 611 Schucht, F., cited 98,505 Schuler, E., synthesis of greenockite 670 Schuler, G., chromium in a phosphate 523, 524 Schurmann, E., corundum in basalt 338 Schiirmann, E., precipitation of sulphides. . . 639 Schutzenberger, P., volatility of silica 273 Schulten, A. de, synthesis of analcite 369 synthesis of gibbsite 497,498 of lanarkite 780 oflaurionite 680 of malachite 663 of molybdenite 698 of northupite and tychite 247 of phosgenite 679 See also Lacroix and De Schulten. Schultz, A. R., cited 163 Schultze, H., synthesis of wulfenite 681 Schulze, EL, and Stelzner, A., artificial tridy- mite 359 artificial willemite 673 Schunett, Lake, analysis of water 170, 175 Schungite 754 Schuster, M., fichtelite 745 Schwager, A., analyses by 96, 98, 99, 100, 518 Bavarian waters 96 loess 509 river silt 505 Schwantke, A., artificial tridymite 359 chemical system of eruptive rocks 425 iron in basalt 328 osteolite and staff elite 520 Schwarz, E. H. L., African hot springs 213 interior of earth 40 primitive atmosphere 56 Schwartzembergite 680 Schwarz, R., forms of silica 363 Schwarzenbach, , the Dead Sea 169 Schweidler, E. von, and Hess, V. F., heat of radium 314 Schweig, M., magnetic differentiation 312 Schweinfurth, G., and Lewin, L., origin of alkaline carbonates 242 Schweitzer, P., analyses by 183, 188, 191, 193 Schwertschlager, J. , water in volcanic gases . . 284 Scolecite 416 Scorodite 208,689 as a spring deposit 208 Scott, A., classification of rocks 422 Scrivenor, J. B., topaz-bearing rocks 408 See also Reid and Scrivenor. Scrope, P., volcanoes 312 Seal, A. N., ozokerite 719 Seamon, W. H., analyses by 644 tallow clays 675 Searlesite .. 247 Secondary enrichment 639-641 INDEX, 811 Page. Sedimentary rocks 537-582 average composition 28 volume of 30,31 Sedimentation 505,506 Seebach, M. t native iron 328 Seidell, A., water analysis 83,156 See also Cameron and Seidell. Seine, River, analysis of water 94 Selenite. See Gypsum. Selenium, distribution 19 in mineral springs 184 Selen sulphur 270 Sella, A., nickel iron 330 Sellards, E. H., phosphate rock 527 Selle, V., origin of kaolin 492 Semper, E., and Blanckenhorn, M., origin of nitrates 257 Semper and Michels, Chilean nitrates 254 Semseyite 678 Senarmont, H. de, precipitation of silver 649 reduction of copper 657 synthesis of ch alcopyrite 659 of pyrargyrite and proustite 653 ofpyrite 333 of quartz 357 of realgar, stibnite, and bismuthinite . 688 of sphalerite 669 sulphides of cobalt and nickel 692 Senarmontite 690 Senderens, J. B. See Sabatier and Senderens. Serajoe River, analysis of water 105 Sericite 391,593,594 Serpentine 376,398,414,415,602-606 Sestini, F., solubility of minerals 478 Severin, E. See Engler and Severin. Sevier Lake, analysis of water 156,174 deposits from 235 Seybertite 393 Seyfert, F., water analysis 102 Shale 545-548,608,609 average composition 28 Shaler, N. S., bog iron ore 530 peat 742 phosphorite 526 soils 508 Shales, metamorphosed 608,609 Shand, S. J., classification of igneous rocks . . 422 Sharpies, S. P., coral 555 phosphate rock 519,521 solubility of calcium phosphate 519 Sharpless, F F. See Lane and Sharpless. Sharwood, W. J., mine waters 631 telluride gold ores 645 Shattuckite 663 Sheep Creek, analysis of water 88 Shelton, H. S., age of earth, etc 153 Shenandoah River, analysis of water 72 Shepard, C. U., jr., phosphate rock 521,522 Shepherd, E. S. See Day and Shepherd. Shepherd, E. S., and Rankin, G. A., binary systems of alumina, etc 292 gehlenite 399 synthesis of corundum 337 of garnet 402 ofmeionite 404 of sillimanite 410 of spinel 342 Page. Shepherd, E. S., Rankin, G. A., and Wright, F E., cristobalite 360 Sherzer, W. H., celestite 578 sand 504 Shiraz, salt lake near, analysis of water 169, 173 Shoal Creek, analysis of water 188 Shonkinite 442 Shonkinose 442 Shorey, E . C. See Schreiner and Shorey. Shoshonose 452,455,456,457 Shutt, F. T., nitrogen in rain 50 Shutt, F. T ., and Spencer, A. G., water analy- sis 70 Sibertzew, N., soils 508 Siberian Ocean, analyses of water 124 Sicha, A., action of carbonated water on min- erals 480 Sickenberger, E., formation of petroleum 731 origin of alkaline carbonates 241 Sidener, C. F., analyses of water 75,76,182 Siderite 417,529,530,571-573 Siderophyllite 392 Sidot, T., synthesis of galena 676 synthesis of greenockite and wurtzite 670 of magnetite 345 oftroilite 333 of zincite 672 Siebenthal, C. E. limestone 557 marl 551 Siedentopf, H., color of salt 231 Siemens, E. W. von, volcanic explosions 289 Siepmann, P., constitution of coal 764 Siewert, M., water analysis 92 Silber, P. G., synthesis ofnephelite 373 Silica, in river waters 108 in sea water 120 volatility of 273 Silicates, hydrolysis of 194 solubility of 132,478-480 Siliceous sinter 205-209 Silico-azo-humic acid 108 Silicon, distribution 20 Silliamn, B., jr., the Dead Sea 169 Sillimanite 409-410,612 Sillimanite schist 614 Silt 504-506 Silva, A. F. de, and d ’Aguiar, A., fluorine in spring waters 192 Silver, distribution 20 in native copper 649 in sea water 121 in volcanic ash 271 occlusion 0 f oxygen by 288 ores of 648,655 Silver Islet, analysis of water from 185 Silver Lake, analysis of water 162, 176 Silver, L. P., nickel deposits 693 Silvestri, O., fluid inclusion in sulphur 578 hydrocarbons in lava 281, 727 iron nitride 272 volcanic gases 265 Silvialite 404 Silvies River, analysis o f water 162 Simek, A. See Jaeger and Simek. Simmersbach, B., and Mary, F., nitrate de- posits 254 Simpson, E. S., laterite 494 native tin 684 812 INDEX. Page. Singer, F., zeolites 417 Singer, L., origin of petroleum 731 Singer, M., constituents o f wood 739 Singerwald, J. T., titaniferous iron ores 469 Sinter, barytic 204 Sinter, calcareous 203 Sinter , ferruginous 572 Sinter, siliceous 205-209 Sipocz, L., analysis by 518 krennerite 645 See also Loebisch and Sipocz. Sippy W. L., analysis by 80 Siserskite 700 Sitaparite 534 Sjogren, H., bog iron ore 530 fluid inclusion in sulphur 578 Scandinavian iron ores 469 vesuvianite 403 Sjollema, B., perchlorates in soda niter 256 Skagit River, analysis of water 86 Skeats, E. M., acid water from sulphur beds. 578 Skeats, E. W., coralline limestone 555 magnesia in coral reef. 567 phosphate rock 528 Skey , W. , analyses by 183, 191, 196, 200 awaruite 330 electrical activity in ore bodies 640 gold sulphide 643 ocean water 122 precipitation of gold 648 of silver sulphide 651 solvents of gold 646 Skinner, W. W., mineral springs 197 underground waters of Arizona 197 See also Forbes, R. H. Skutterudite 692 Slate 545-548 Slichter , C. S. , volume of ground water 33 Sloan, E . , clays 508 Slosson, E. F., water analyses 79, 163 Smaltite 692,694 Smart, C. , water anal vses 155 Smith, A. W. See Mabery and Smith. Smith, B. H. See Haywood, J. K. Smith, E. A., phosphate rock 528 Smith, F. P. , tungsten ores 699 Smith, G. O., molybdenite 698 Smith, G. O., and Willis, B., iron ores 531 Smith, J., river waters 93 Smith, J. G., cited 162 See also Failyer and Smith. Smith, J. L. , analysis by 186 native iron 329 Smith, J. P.,eclogite 599 glaucephane rocks 388,591 lawsonite rocks 411 Smith, N. R. See Kellerman and Smith. Smith, R. A., oxygen of the atmosphere 42 peat 742 Smith, Watson, resins in lignite 748 Smith, W. S. T., zinc deposits 675 See also Ulrich and Smith. Smithite 653 Smithsonite 672 Smits, A. , and Endell, K. , cristobalite 360 Smoky Hill River, analysis of water 80 Page. Smolensky, G., synthesis of titanite 350 Smoot, L. E . , analysis by 198 Smyth, C. H., jr., alkaline rocks 446 alteration of pyroxene 377, 378 Clinton iron ores 531 corrosion of quartz 363 limestone 623 losses of atmospheric oxygen 55 melilite rocks 400 metamorphosed gabbro 597 solubility of rocks 480, 481 talc 415,604,605 Smyth, H. L., iron ores 346 Snake River, analysis of water 84 Snider, L. C., zinc ores 675 Soap Lake, analysis of water 162, 177 Soapstone 605 Soda Lake, soda from 238 Soda Lakes, analyses of water 159, 177 Sodalite 282,373-375 Sodalite syenite 375, 448, 450 Sodalite trachyte 375 Soda niter 247, 249, 254-259 Soddy, F., origin of helium 317 Sodium, distribution 20 metallic, in salt 231 sulphate deposits 233-235 Sodium chloride, in rainfall 51-53 See also Salt. Soellner, J., rhoenite 388 Soils 491,499,508 SokolofT, N. V. , origin of petroleum 727 Sollas, W. J., chert and flint 543 geologic time 149, 152 order of deposition of minerals 307 quartzite 607 Solomon River, analysis of water 80 Soltmann, R., melanite 401 Solubility of minerals 478-483, 630 Sommerfeldt, E., classification of igneous rocks 425 Sommerlad, H., synthesis of chalcostibite 661 syntheses of sulphosalts 654 sulphosalts of lead 678 Sommermeier, E. E., coal analyses 746, 747 Sonden, K., cited 49, 142 Sonnenschein, F. L., amalgam 644 Sonstadt, E., caesium and rubidium in sea water 121 gold in sea water 121 iodine in sea water. . : 119 Sorby, H. C., calcite and aragonite 552 enlargement of quartz grains 538 formation of magnesium carbonate 560, 561 of siderite and limonite 571 magnesium sulphate in gypsum 560 shale 547 Soret’s principle 309 Sosman, R. B. See Day and Sosman. Souesite 330,331 Sowetow, S., Sea of Aral 166 Spaeth, E., water analyses 97, 101 Spalding, E. P., Terlingua mines 665 Spangenberg, K., synthesis of dolomite 560 tests for dolomite 564 Spaulding, H. S., analyses by. 75, 76, 77, 78, 79, 80, 82 INDEX. Page. Spencer, A. C., Franklin zinc ores 676 iron ores 531 magmatic waters 213, 634 secondary enrichment 660 Spencer, A. G. See Shutt and Spencer. Spencer, Herbert, nature of earth’s interior. . 57 Spencer, J. W., bauxite 497 Spencer, L. J., jamesonite 678 tellurides 644 See also Prior and Spencer. Sperry, F. L. See Penfield and Sperry. Sperrylite 19,700,704 Spessartite 401 Spezia, G., effects of pressure 585 formation of quartz and opal 363 metallic sodium in salt 231 solubility of quartz 363, 481 sulphur deposits 577 Sphserite 520. Sphaerocobaltite 694 Sphalerite 669-671, 675, 741 Sphene 350 Spica, M., and Halagian, G., Italian waters.. 96 Spiegel, L., fichtelite 745 Spielmann, P., jet 746 Spilker, A. See Kramer and Spilker. Spinel 341-343,398 Spirek, V., mercury ores 669 Spodumene 379,380,687 Spokane River, analysis of water 85 Spreustein 375 Spring, R., platinum ores 702 Spring, W. , argentite formed by pressure — 650 colorati on of clay 508 compression of chalk 556 of peat 760 humus and iron in waters 505, 531 precipitation of organic matter by iron. . . 506 sedimentation 506 Spring, W., and Prost, E., water of the Meuse 94,114,118 Spring River, zinc in 188 Springs, potable, analyses of 64 Spurr, J. E . , alaskite and tordrillite 434 borates 246 dolomitization 569 glauconite 573 iron ores 572 magmatic quartz veins 643 ore deposits 634 primary pyrrhotite 335 succession of igneous rocks 311 Srebenica, spring, analysis 188 Stabler, H . , interpretation of water analyses . . 62 river waters 68 See also Dole and Stabler. Stackmann, A., Lake Durun 165 Stafifelite 520 Stahl, A. F., origin of petroleum 733 Stahl, W., on Karaboghaz 165 zinc sulphide 669 Stanley, F. C. See Penfield and Stanley. Stannite 683 Stapff, F. M., bog-iron ore 530 Starnbergersee, analysis of water 96 Stassfurt salts 221-228, 250 Staurolite 411,612 813 Page. Steamboat Springs, analysis of 186 sinter from 206 Steatite 415,605,606 Stecher, E., carbide theory of volcanism 281 Steenstrup, K. J. V., graphite in basalt 328 Steidtmann, E . , alteration of rocks 483- dolomite 563 Steiger, G., analyses by 86, 123, 161, 162, 163, 185, 193, 232, 445, 453, 462, 468, 480, 504, 508, 514, 527, 528, 546, 558, 570, 573, 574, 596, 606, 614, 615 copper in lava 629 Mississippi silt 505,629 solubility of minerals 480 synthetic hydrocarbons 723 See also Clarke and Steiger. Stein, G., formation of quartz 360 fusion of quartz and silicates 294 Stein, S . , artificial coal 762 Steinmann, G., precipitation of calcium car- bonate 551 Stelzner, A., artificial gahnite 673 associates of perofskite 349 Bolivian tin ores 683, 687 melilite rocks 409 See also Schulze and Stelzner. Stelzner, A., and Bergeat, A., ore deposits. . . 626 Stelzner, A., and Schertel, A., tin in blende. . 684 Stelzner, A., and Schulze, H., fayalite in slags 390 Stelzner, A . W . , lateral secretion 627 RioSaladillo 164 ore deposits 626 St8p, J., and Becke, F., uranium ores 707 Stepanow, , analysis of water 166 Stephanite 653,654 Stercorite 521 Sternbergite 653 Sterrett, D. B. See Pratt and Sterrett. Stevenson, J., primitive atmosphere 55 Stibiconite 690 Stibnite 688 Stieglitz, J., carbon dioxide of the atmos- phere 145 Stilbite 416 Stilpnomelane 397 Stockvis, C. S. See Saltet, R. H. Stober, F., synthesis of cotunnite 679 Stokes, H. N., analyses by 28,64, 189, 435, 439, 440, 442, 444, 447, 450, 452, 458, 461, 462, 473, 541, 546, 558, 592, 610, 615, 619, 632 formation of copper sulphides 660 of sphalerite 675 precipitation of copper 656, 657 of lead sulphide 677 pyrite and marcasite 334 solution and deposition of silver 649, 651 solution of gold 646 tallow clay 675 Stoklasa, J., volcanic nitrogen 272 Stolba, F., on the Moldau 98 River Radbuza 98 synthesis of galena 676 Stolzite 681,699 Stone, C. H., analyses of water 75, 160 Mississippi silt 505 Stone, G. H., asphalt 720 814 INDEX. Page. Stone, R. W., gold in coal 646 Storer, F. H. See Warren and Storer. Storms, W. H., borate deposits 248 Stose, G. W., wavellite 520 Strecker, A. and H., marine mud 515 Stremme, H., allophane, halloysite, etc 500 coal 740 decomposition of basalt 483 humus substances 484 kaolinization 492 polymerization of hydrocarbons 733 See also Gagel and Stremme. Streng, A., bauxite 496 Strengite 520 Strigovite 397 Strombeck, A. von, electrical activity in ore bodies 640 Stromeyer, C. E., fusibility and pressure 291 Stromeyerite 653 Strong, W. W., radioactivity 314,317 Strontium, distribution of 20 in sea water 121 Strutt, R. J., age of minerals 318 gases in rocks 281 helium and geologic time 317 helium in beryl 319 helium in saline minerals 223, 317 radioactivity of rocks 19, 314, 316 radium in ocean water 122 Struvite 521 Stubbs, W. C., phosphate rock 528 Stutzer, A., and Hartleb, R., bacterial decom- position of cement 485 Stutzer, A., and Reich, A., water analysis. . . 168 Stutzer, O., cobalt ores 691 graphite 328 juvenile springs 213 kaolinite 492 magmatic bomite 335 magnetite ores 346 origin of sulphur 577 primary calcite 418 sulphides in coal 741 water of pitchstone 284 Stutzite 652 Stylotypite 661 Suess, E., vadose and juvenile waters 213 volcanic additions to oceanic salts 141 Siissenguth, H., cited 98,505 Suez Canal, analysis of water 125 Sullivan, E. C., copper sulphides 660 deposition of copper 664 Sullivan, G. See Kastle, J. H., etc. Sulphates, reduction by micro-organisms. . 148, 515 Sulphates in sea water 138, 139 Sulphides, solubility of 630 Sulphoborite 225,250 Sulphohalite 247 Sulphur, distribution 29 in atmosphere 45 in petroleum 718 native 247,270,576-578 Sulphur Bank, analyses of waters from 197 Sulvanite 706 Summer Lake, analysis of water 161, 176 Sundell, J. G., cancrinito syenite 375 Page. Sungi Pait, Brook, analysis of water 199 Superior, Lake, analysis of water 69 Susquehanna River, analysis of water 71 Sutton, J. R., diamond 325 Svanberg, , analyses by 702 Svanbergite 682 Svedmark, E., uralitization 590 See also Tornebohm and Svedmark. Svendsen, S., analyses of dissolved air 142 Sweden, rivers of 103 Swinton, A. A. C., occlusion of gases by glass 276 Switzerland, lakes of. 95 Syenite 439-441 Syepoorite. See Jaipurite. Sylvanite 644,645 Sylvinite 224 Sylvite 224,228 Syngenite 227 Syntagmatite 387 Syracuse, N. Y., brine, analyses of 182 Szabo, J., primary iolite 406 Szadeczky, J. von, bauxite 496 Szajnocha, , origin of petroleum 730, 736 Szathmary, L. von, wollastonite 378 T. Taal Volcano, analyses of water from 200 Tabbyite 719 Taber, S. See Watson and Taber. Taboury, F., selenium in spring waters 184 Tachhydrite 224 Tacke, B. See Minssen and Tacke. Tagar Lake, analysis of water 170, 174 Tahoe, Lake, analysis of water 158 Takano, S. See Mabery and Takano. Talbot, J. H. See Binney and Talbot. Talc 415,602-606 Tallow clay 675 Talmage, J. F., water analyses 155 Tamentica, Lagoon, analysis of water 164, 174 Tanatar, S., origin of alkaline carbonates 241 Taney, Lac 95 Tantalite 710 Tantalum, distribution of 20 native ✓ 711 sources of 710-711 Tapajos, River, analysis of water 91,107 Tapalpite 653 Tappeiner, H., formation of marsh gas 729 Tarassenko, W., constitution of feldspar 364 Tasmanite 746 Tate, N., analysis of water 69 Taylor, F. W., analysis by 231 Taylor, H., analysis of cannel 751 Taylor, R. A., cited 140 Taylor, W. H., analysis of water cited 72 Teall, J. J. H., classification of igneous rocks.. 425 dedolomitization 623 differentiation 312 eutectic mixtures in rocks 423, 425 origin of serpentine 414 phosphate rock 522,528 phosphatized trachyte 521 the Scourie dike 590 Teallite 678,683 INDEX, 815 Page. Tegemsee, analysis of water 96 Tehamose 435 Teisseyre, W. See Mrazec and Teisseyre. Tekir-Ghiol, Lake, analysis of water 172, 173 Tellurides 644, 645, 648, 652, 653, 658, 688 Tellurium, distribution 20 in copper 658 in sulphur 270 Temiskamite 692 Tengerite 712 Tennantite 653,661 Tennessee River, analysis of water 78 Tenorite 265,271,662 Tephroite 389 Terbium 20,711 Terlinguaite 664 Termier, P., alunite 259 lawsonite 411 leverrierite 611 optical variations in zoisite 406 riebeckite rocks 389 Terreil, A., artificial dolomite 561 native platinum 701 water analyses 167 Tesch, P., solubility of fossils 552 T etlow, W . E . , wat er analysis 93 Tetradymite 688 Tetrahedrite 653,661 Thailium, distribution 20, 28 Thames, River, analysis of water 93, 107 Than, C. von, ionic statement of water anal- yses 59 Thenard, P., silico-azo-humic acid 108 Thenardite 234, 247, 249, 255 Theralite 445 Thermonatr it e 239 Tidy, C. M., cited 93 Thiele, F. C., Texas petroleum 717 Thiene, H., nature of earth’s interior 40, 57 Thiessen, R., See White and Thiessen. Thinolite 158 Thiophanes 718 Thiosulphates in spring waters 195 Thoma, , gases in iron - 287 Thomas, J. W., gases in coal 757-760 Thomas, P., phosphorite 525 Thompson, A. B ., formation of bitumens 734 Thomsen, J., thermochemistry of sulphides . . 651 Thomson, J. A., matrix of diamond 325 Thomson, R. D., cited 93 Thomsonite 416 Thorianite 711 Thorite 711 Thorium, distribution 20 sources of 711 Thorkelsson, T., hot springs of Iceland 261 Thornton, W. M., jr., analyses by 468 Thorogummite 712 Thorpe, T. E., analyses by 184, 186, 187 Thorpe, T. E., and Morton, E. H., analysis of seawater 123 Thoulet, J., chert 543 desert sand 508 lakes of the V osges 94 Page. Thoulet, J„ sedimentation 506 solubility of calcium carbonate 128 of silicates 132 Thresh, M., manganese nodules 533 Thiirach, H., occurrence of zircon and tita- nium minerals 354 Thugutt, S. J., allophane, halloysite, etc 500 alteration of corundum 340, 481 alteration of wollastonite 378 cancrinite 374 composition of sodalite 374, 375 gibbsite and diaspore 498 leucite and analcite 368,369 nephelite 372 reactions of calcite and aragonite 552 Thulium 21,711 Thuringite 397,575 Tidy, C. M., water analyses cited 93 Tiemannite 664 Tietze, E., atmospheric transport of salt 52 Tietze, O., phosphorite 525 Tilden, W. A., gases in rocks 275 Tillo, A. von, areas of igneous and sedimen- tary rocks 117 Tilson, B. S., cited 82 See also Fraps and Tilson. Tin, distribution 21 in sinter 206,684 ores 683-687 Tinetzky Lake, analysis of water 166, 175 Tinguaite 444,447,449 Tinstone. See Cassiterite. Titanite 350 Titanolivine 389 Titanium, distribution 21 Tomebohm, A. E., melilite rocks 400 Tomebohm, A. E., and Svedmark, E., scap- olite rocks 596 Tomebohm, A. S., enlargement of quartz grains 538 Tolman, C. F., jr., oceanic carbonic acid 145 secondary enrichment 639 Tolman, C. F., jr., and Clark, J. D., electro- lytic behavior of copper 657 Tolomei, G., iron bacteria 530 Tombigbee River, analysis of water 74 Tonalite 456 Tonalose 453,461 Tookey, C., analyses by 743, 746, 747 Topaz 408,409,410,601 Torbanite 733 Tordrillite 434 Tornoe, H., density of sea water 126 analyses of dissolved air 142,144 Torrico y Meca, vanadium in coal 706 Torrey, J. See Barbour and Torrey. Toscanose 436,437,452,473 Tourmaline 412-413 Tourmaline hornstone 615 Tower, W. S., Chile nitrates 254 Trachyte 439 Track Lake, analysis of water 163 Transition temperatures 282 Transvaalite 694 816 INDEX. Page. Traphagen, W. , cited 79 Traube, H. , sublimation of minerals 273 synthesis of beryl 414 of rutile 351 wurtzite as furnace product 669 zincite 672 See also Bourgeois and Traube. Traunsee, analysis of water 96 Travaglia, R., formation of sulphur deposits. 579 Travers, M. W., gases from meteorites 287 gases from minerals and rocks 275 Travertine 203,550 Treadwell, F. P., and Reuter, M., solubility of calcium bicarbonate 128,129 Trechmann, 0. O., pseudogaylussite 158 Tremolite 383,387 Trener, G. B., genesis of barite 581 Tridymite 357-363 Trinkerite 746 Triphylite 686 Tripuhyite 691 Trobridge, F. G., gases in coal 760 Troilite 332-335 Trona 1 238,239,240,247 Troost, L. See Deville and Troost. Troost, L., and Hautefeuille, P., gases in iron. 287 Troostite 672 Truchot , P. , monazite, thorite, and zircon ... 356 Truckee River, analysis of water 158 Trueman, J. D., diagnostic criteria 624 Tschermak, G., alteration of atacamite 662 carbon in meteorite 288, 728 constitution of pyroxenes 383 composition of tourmaline 413 gaseous occlusions 287 scapolite group 404,597 serpentine 602 theory of chlorites 397, 398 of micas 393 Tschirwinsky , W . , phosphorite 528 podolite 355 Tsuneto, K. , phosphorite 528 Tucan, F . , bauxite 499 dolomitization 563 Tucker, G. P. See Pemberton, H. Tufa, barytic 204 Tufa, calcareous 203 Tulare Lake, analyses of water 160, 177 Tungsten, distribution 21 ores 699 Tungstic ocher 699 Tuolumnose 439 Turgite 529 Turner, H. W., California diamonds 326 quartz-alunite rock 259, 497 Turner, H. W., and Rogers, A. F., primary sulphides 660 Turquoise 520 Turrentine, J. W., brines and bitterns 181, 233 Tuscarora sour spring, analysis 198 Tyrolite 662 Tychite 247,662 Tyrrell, G. W., analcite rocks 371 quantitative classification of igneous rocks 433 Tyrrell, J. B., native iron 331 Page. Tysonite 336 Tyuyamunite 709 U. Ubbelohde, L. , optical activity of petroleum . 735 U dden, J. A . , aerial denudation 138 Uglow, "W. L. , secondary silicates in limestone 622 Uhlig, J. , garnet 401 komerupine 381 kryptotile and prismatine 393,611 Uintaite 719,720 Ule, W., the Mansfelder lakes 95, 102 Ulexite 246,248,249,250,251,255 Ulke, T., tin deposits 686 Ullik, F., on the Elbe 98, 118 Ullmannite 692 Ulrich, E. O. See Hayes and Ulrich. Ulrich, E. O., and Smith, W. S. T., fluorite . 582 Ulrich, G. H. F., awaruite 330 Umangite 658 Umatilla River, analysis of water 85 U mlauff , A . F . , mercury deposits 668 Umpqua River, analysis of water 86 Umptekose 445 Unakite 326,598,599 Uralifce 384,590 Uralitization 589-591 Uralose 467 Uraninite 707,708 Uranium, distribution 21 ores of 705-710 See also under Radioactivity. Urao. See Trona. Urbain, G., rare earths in fluorite 335 rare metals in blende 669 ytterbium 21 Urbainite 348,469 Urbas, M., silicate fusions 306 Urmi, Lake, analysis of water 169, 173 Urtite 445 Urtose 445 Uruguay River, analysis of water 91, 107 silica in 108 Usiglio, J., concentration of sea water 218-220 Ussing, N. V., alteration of arfvedsonite 389 Utah Hot Springs, analysis 183 Utah Lake, analysis of water 156 Uvaldose 459 Uvanite 710 Uvarovite 401 V. Vaalose 462 Vadose waters 213 Valentin, J., fluorite 582 Valentine, W., analysis by 473 Valentiner, S., cited 223 Valentinite 690 Van, Lake, analysis of water 169, 177 Vanadic ocher 706 Vanadinite 682 V anadium , distribution 21 in bauxite 705 in bitumen 706 in salt clay 222,705 ores of 705-710 INDEX, 817 Page. Van Hise, C. R., actinolite magnetite schist. . 384 alterations of corundum 341 of hematite 348 amount of carbon dioxide in atmosphere. 46 average composition of clays, schist, etc. 619, 620 chert 544 ferruginous schists 609 fineness of sand particles 515 formation of iron ores 572 magmatic quartz veins 643 magmatic waters 634 mica schist 615 ore deposits 626 origin of magnetite 346 porosity of sand 538 quartzite 607 relative proportions of sedimentary rocks. 32 volume changesin alteration of minerals. 585,589 volume of ground water 33 zinc deposits 675 zones in lithosphere 584 See also Irving and Van Hise. Van Hise, C. R., and Leith, C. K., mine waters 631 Van Horn, F. R., alkali-hornblende 387 Van Niiys, T. C., and Adams, B. F., cited 45 Van Riesen, , analysis by 606 Van’t Hoff, J. H., geological thermometer. . . 228 on Stassfurt salts 224, 228 syntheses of borates 248 Vant Hoff, I. H., and Barschall, H., on glaserite 223 Van’t Hoff, J. H., and Farup, P., marine anhydrite 226 Van’t Hoff, J. H. Kenrick, F. B., and Daw- son, H. M., tachhydrite 225 Van’t Hoff, J. H., and Meyerhoffer, W., on langbeinite 224 Van’t Hoff, J. H., and Weigert, F., formation of anhydrite 226 Vanthoffite 223,228 Van Wagenen, T., soda niter 259 Van Winkle, W., analyses by 74, 75, 76,77,78,79,81,82,83, 84, 85, 86, 160, 161, 162 Van Winkle, W., and Eaton, F. M., waters of California 83 Variscite 520,522 Varon, G. See Henriot and Varon. Varvicite 534 Vasculose 761 Vater, H., alkaline carbonates 241 anhydrite 226 artificial hematite 347 calcite and aragonite 551, 552 forms of calcium carbonate 552 Vater ite 552 Vaubel, W., aragonite 551 Meigen’s reaction 552 Vaughan, T. W., fuller’s earth 508 precipitation of calcium carbonate 549 Vauquelinite 681 Vaux, F., coal analyses 751, 753 Veatch, J. A., boron in sea water 120 Veatch, O., bauxite 497 V egetation, as agent of rock decomposition . 483 , 484 97270°— Bull. 616—16 52 Page. Veins, metalliferous 634-638 Velain, C., artificial tridymite 359 volcanic gases 268 Venable, F. P., on periodic law 37 Venanzite 459 Venanzose 459 Verde-antique 603,622 Vermiculite 396,397 Vermilion 665 Vernadsky ,W., andalusite, kyanite, siiliman- ite '. 409,612 artificial corundum 340 calcination of dumor tier ite 412 of topaz 409 formation of sillimanite 409, 611 of spinel 343 fusion of muscovite 340, 396 occurrence of native elements 28 rare elements in rocks 28 rubidium in feldspar 365 Vernadsky, W., and Popo: ', S. P., borax 250 Vernon- Harcourt,L. V., sedimentation 506 Versailles alum well, analysis 188 Vesterberg, A., dolomite and magnesite 564 Vesuvianite 403,601 Veszelyite 672 Vetter, F. See Cornu and Vetter. Vichy, spring deposits 204,205 Vichy waters, analyses 191, 192 VictoriaNyanza, analysis of water 106 Vierthaler, A. , cited 122 Viezzenose 445 Vignon, L., experiments on coal 764 Villarello, J. D., mercury ores 664 Ville, L. , River Chelif 66 Villiaumite 373 Vils, River, analysis of water 101 Vinagre, Rio, analysis of water 199 Viola, C., occurrence of lawsonite 411 Violette, , charcoal 760,761 Virginia Hot Springs, analysis of water 193 Virginose 468 Viridite 600 Viry phosphatic water, analysis 197 V istula River , analysis of silt 505 analysis of water 102 Vivianite 520 Voelcker, J. A., composition of apatite 354 Voelckerite 523 V ogel, H. , platinum in metallic ores 704 Vogelsang, H., viridite 600 Vogt, J. H. L., anorthite in slags 365 apatite in slag 355 augite in slags 382 bog iron ore 530 cassiterite as a furnace product 353,684 chromite deposits 344, 697 distribution of the elements 27,39 of vanadium 705 6utectic mixtures in rocks 302-304 eutectics in classification of rocks 423 formation of hematite 347 of magnetite 345 of pyroxene 379 fusibility and pressure 291 818 INDEX. Page. Vogt, J. H. L., fusion of garnet 401 gehlenite group . 399 ionization in magmas 306 magmatic iron ore 312,346 magmatic pyrrhotite 335, 693 magmatic waters 634 manganese ores 535 melting points of minerals 292, 293 mica in slag 394 native silver 649 olivine in slags 390 on assimilation theory 310 ore deposits 626 platinum in pyrrhotite 704 solubility of sulphides in magmas 305,335 synthetic enstatite 376 tin deposits 686 wollastonite in slags 377 V ohl , H ., water analysis 97 Voit , F . W ., nickel deposits 693 origin of diamond 325 Volborthite 706 Volcanic dust and climate 48 Volcanic gases 269-290 Volcanic explosions 285-289 Volcanic mud and sand 512 Volcanism, ascribed to radioactivity 316 hot springs and 214 Voltzite 669 V ouga, , origin of petroleum 732 Vrbaite 20 Vredenburgite 534 Vucnik, M., formation of augite 383 formation of hercynite 343 of magnetite 345 fusion of acmite 380 of mineral mixtures 300,306 Vukits, B. , formation of augite 383 formation of magnetite 345 of spinal 343 fusion of mineral mixtures 300, 306 W. Wabash River, analysis of water 78 Wad 533,534 Wade, H. R. See Failyer, G. H. Wadsworth, M. E., chromite 343 native copper 656 Waggaman, W. H. See Patten and Wagga- man. Wagner, P. A., diamond 325 Wagoner, L., gold and silver in deep-sea dredgings 122,642 gold and silver in rocks 642 gold in sea water 122 Wahl, A., experiments on coal 764 Wahl, W. H., composition of meteorites 40 Waidner, C. W., and Burgess, G. K., tem- perature of electric arc 273 Waini River, analysis of water 90 Wait, C. E., antimony deposits 690 Wait, F. G., analyses by 88, 162, 185, 191 Wakarusa River, analysis of water 80 Walchensee, analysis of water 96 Walden, P, origin of petroleum 735 Walker, P. H., analysis by 534 Page. Walker, T. L., magmatic differentiation 311 nickel deposits 692,693 primary calcite 418 temiskamite 692 Walker Lake, analysis of water 158, 177 W alker River, analysis of water 158 Wallace, E. C. See Richardson and Wallace. Wallace, R. C., dolomite 565,569 gypsum and anhydrite 232,576 silicate fusions 300 Wallace, W., sandstones 541 Waller, E., analyses by 155,344 Waller, S. A., and Twelvetrees, W. H., tin deposits 685 Wallerant, F., chalcedony 357 Wallich, G. C., flint 543 Walter, H. See Wegscheider and Walter. Walther, J., calcareous algae 555 criticism of Ochsenius 220,226 desert salts 235 origin of graphite 327 laterite 493 Walther, P., native tantalum 711 Wanklyn, J, A., free iodine in spring water. . 183 Ward, L. K., tin deposits 685 Ward, W. J., analysis by 746 Wardite 520 Waring, G. A., springs of California 216 Warington, R., absorbent power of hydrox- ides 501 ammonia in rainfall 50 chlorides in rain 52 decomposition of calcium phosphate 520 origin of boric acid 245 sulphur in the atmosphere 65 Warren, C. H., anorthite in limestone 367 iron-anthophyllite 383 minerals in sand 504 urbainite 348,469 See also Hidden and Warren ; Johnson and Warren. Warren, C. M., and Storer, F. EL, artificial petroleum 724 Rangoon oil 718 Warrenite 678 Warsaw, N. Y., brine, analysis of 182 Warth, EL, calcium carbonate 551 classification of igneous rocks 421 gibbsite 495 Warth, H. and F. J., laterite and bauxite 495 Washington, H. S., alteration of biotite 395 analcite basalt 370, 371 analcite in tinguaite 370 analyses by 447, 450, 592 average composition of igneous rocks <25 distribution of the elements 35 glaucophane rocks 388,591 kaersutite and linosite 389 leucite in igneous rocks 448 quantitative classification 432, 433 relative abundance of minerals 419 Washington, H. S., and Larsen, E. S., mag- netite basalt 346, 468 Washington, H. S., and Wright, F. E., car- negieite 364 See also Kunz and Washington. INDEX. 819 Page. Water, influence of, on magmas . . .’ 297 Water analyses, statement of 59 Water ee River, analysis of water 73 Water glass 297 Waters, classification of 180, 181,201 Waters, J. W., radioactive minerals 315 Watson, H. E., helium and neon in air 41 Watson, T. L., barite 581 bauxite 496,497 decomposition of diabase 488 gold in sillimanite 642 kragerite 469 manganese ores 535 nelsonite 468 Virginia rutile 352 zinc deposits 675 Watson, T. L., and Hess, F. L., zirconiferous sandstone 354 Watson, T. L., and Taber, S., nelsonite 352 Watts, W. L., waters accompanying petro- leum 732 Wavellite 520 Way, J. T., absorption of potassium by soils.. 501 Wayne, E. S., analysis by 183 Weathering, belt of 584 Weber River, analysis of water 156 Websky, J., analyses of peat 742 gas from peat 757 Websky ite 415 Websterite 463,464 Websterose 464 Webb, C. B., barytic sandstones 539 Webb, C. B., and Drabble, G. C., fluorspar. . 582 Wedding, H., and Fischer, T., gases in iron.. 287 Weed, W. H., copper ores 659 gold in igneous rocks 332 iron sinter 572 on siliceous sinters 206, 207 ore deposits 626,634 secondary enrichment 639 tin deposits 686 travertine 550 Weed, W. H., and Pirsson, L. V., alteration of leucite to analcite 371 origin of corundum 340 orpimen t and rea lgar 689 Weed, W. H., and Spurr, J. E., ore deposits. 626 Weeks, F. B., tungsten ores 699 Weeks, F. B., and Ferrier, W. F., phosphate rock 527 Weeks, J. D., manganese deposits 535 W eems , J. B . , lead and zinc i n 1 imestones 674 Wegener, A., composition of atmosphere 41 Wegscheider, R., and Walter, H., gaylussite and pirssonite 247 Wehrlite 463,464,688 Wehrlose 464 Weibull, M., formula of iolite 405 manganese in spring water 205 vesuvianite 403 Weidman, S., clays 507 iron ores 572 Weigand, B., serpentine 602 Weigel, O., solubility of sulphides 631 Weigert, F. See Van’t Hoff and Weigert. Page. Weingarten, P. See Jannasch and Wein- garten. Weinschenk, E., constitution of pyrite 334 garnet group 401 nickel ores 692 _ nontronite 491-492 origin of graphite 327 serpentine 602 synthesis of apatite 355 ofargentite 650 oi chalcoc.ite and covellite 659 of cinnabar 666 of galena 677 of orpiment and stibnite 688 sulphides of cobalt and nickel 694 talc pseudomorphs 605 Weiss, F., origin of kaolin 492 Weiss, K. E., chromite deposit 697 Weisswasser, analysis of water 99 Weith, A. J., analyses by 80 Weld, C. M., iron ores 531 Wellcome, H. S., analysis of salt 231 Weller, A., nitrogen in petroleum 718 Wells, G. M., phosphate rock 527 Wells, H. L., sperrylite 704 Wells, H. L., and Penfield, S. L., sperrylite. . 704 Wells, J. W., arsenic mine 690 molybdenite 698 Wells, R. C., copper in basalt 629 electrical potential of ores 640 mine waters 631,632 palladium in plumbojarosite 704 precipitation of sulphides 640 relative solubility of carbonates 641 vanadium in asphalt 706 Wellsite 416 Welsbach, Auer von, ytterbium 21 Wendebom, , mercury deposits 668 Wendt, A. F., tin deposits 687 Werling, P., loess 509 Werner and Fraatz, samsonite 653 Wemerite 404 Werveke, L. van, occurrence of chloritoid 395 iron ores 575 Weser River, analysis of water 102 Westgate, L. G., epidote-quartz rock 598 metamorphosed limestone 623 Westphal, J., cited, on Stassfurt salts 221 West Baden Spring, analysis 189 Wethered, E. B., oolite 550 Weyberg, Z. , synthesis of acmite 380 ofsodalite 374,375 the silicate K 2 Al 2 Si0 6 387 Wheeler, A. S., analyses of sea water 123 Wheeler, H. A., blende in lignite 671 clays 508 lead silicate 683 See also Luedeking and Wheeler. Wheeler, W. C. See Clarke and Wheeler. Wherry, E. T., camotite 709 Whewellite 741 Whipple, G. C., and Jackson, D. D., chlorine maps 51 Whitby well, analysis 185 White, A. F., chemical denudation 113 820 INDEX, Page. White, C.J., ocean water 122 White, D., petroleum 737 White, D . , and Thiessen, R., origin of coal . . . 740, 741,748,763 White, I . C. , grahamite. . . 720 White, J., barium in artesian water 200, 204 White, W. P. See Allen and White. Whitehead, W. L. See Lindgren and White- head. White Island hot lake, analyses of water 200 White River, analysis of water 78 White Sea, analysis of water 124 Whitfield, J. E . , analyses by 79, 203, 205, 207, 208, 435, 453, 464, 572 Whitman, A . R. , origin of pyrite 334 Whitney, J. D., zinc deposits 675 Whitneyite 658 Whittle, C . L . , ottrelite schist 613 Wibel, E., cited 122 W ichmann, A . , alteration of iolite 406 glaucophane rock 591 minerals in sand 503 sericitic rocks 593 Wiegand, E. See Beilstein and Wiegand. Wieland, G. R., siliceous oolite 544 Wiesbaden, analysis of water 184 Wiesler, A., gold in sea water 122 W iesner , G . H . , nitrogen and chlorine in rain . 50 Wilder, F. A., gypsum 232 W ilke, E . , rubidium in potash salts 222 Wilkinson, C., precipitation of gold 648 Will, W., and Pinnow, J., diamonds in meteorite 324 Willamette River, analysis of water 85 Willemite 671,673,676 Williams, A., gold sulphide 643 Williams, C. P., zinc in waters 189,632 Williams, F. H., hydrocarbons in iron 722 Williams, G. F., matrix of diamond, .s- 325 Williams, G. H., allanite and epidote 408 chloritization 600 corundum, emery, and spinel 340 epidotization 407,597,598 occurrence of magnetite 346 ofperofskite 349 of pyroxenes 383 of spinel 343 piedmontite in rhyolite 407 saussurite rocks 595 sericitization 594 serpentine from peridotite 414 uralitization 589 W illiams , I . A . , clays 508 micrometric analysis of rocks 475 Williams, J., cited 50, 52 Williams, J. F., bauxite 498 pseudoleucite 371 See also Brackett and Williams. Williams, K. See Ebaugh and Williams. Willis, B., cited 75 Willm, E., analyses by 173, 195 See also Jacquot and Willm. Willyamite 692 Wilm, , palladium gold 644 Wilmington Lake, analysis of water 163, 177 Page. Wilsmore, N. T. M. See Craig, A. W. Wiluite 403 W inchell, A. , cosmical atmosphere 54 Winchell, A. N. , chalcopyrite and bornite ... 658 classification of igneous rocks 422 origin of graphite 328 Winchell, H. V., chalcocite 660 W inchell, N . H . , silicated iron ores 573 Winchell, N. H. and H. V., iron ores 572 Winkler, C., origin of nickel-iron 330 trona 240 uranium in coal 710 Winnemucca Lake, analyses of water 158, 176 W inslow , A . , zinc ores 674 W isconsin River , analysis of water 76 Witt, H. M., river water 93 Witter, F. M., gas well 729 W ittich, E . , cassiterite 685 Wittichenite 661,662 Wittjen, B. See Precht and Wittjen. Wittstein, G., water analysis 101 Woehler, F., carbon in meteorites 728 gases from meteorites 288 synthesis of pyrite 333 See also Deville and Wohler. W oehler, L. , and Kasamowski, color of salt. . 231 Wohlerite 383 W oemitz, River, analysis of water 101 Wolf , T . , volcanic gases 266 Wolfachite 692 Wolfbauer, J. F., water of the Danube. 101, 102, 505 Wolff, F. von, volcanism and radioactivity. . 317 W olff , J. , artificial diamond 323 waters of Mecklenburg 102 Wolff, J. E., Franklin zinc ores 676 ottrelite 613 Wolframite 699 Wollastonite 377,378 Wollastonite gneiss 624 W olle, C. A. , analysis of spinel 342 Wologdine, S. See Le Chatelier and, Wolog- dine. Wood 739 W ood, A. See Campbell and W ood. Woodward, R. S., geodetic data 22 Woodward, R. W., analyses by 157, 203,206,236,237,544 W ooten. See Magnenat and W ooten. Workman, R., primary calcite 418 Woyno, T. J., glaucophane schists 591 Wright, A. W., gases from meteorites 287 gases in rocks 275 See also Hawes and Wright. Wright, F. E ., crystallized copper and silver . 657 See also Allen, E. T.; Hillebrand, W. F.; Shepherd, E. S. Wright, F. E., and Larsen, E. S., quartz as geological thermometer 360 Wroezynski, A. See Briner and Wroezynski. Wiilfing, E. A., composition of tourmaline. . . 413 Wurmsee, analysis of water 96 Wiist, E., kaolin 492 Wulf, H., scapolite rock 597 Wulf, J., wollastonite rock 377 Wulfenite 681,698 INDEX. 821 Page. Wurtz, EL, analysis of water cited 71 huntilite and animikite 650 solvent of gold 646 Wurtzilite 720 Wurtzite 669-671 Wyatt, F., phosphates 526 Wyomingite 447 Wyomingose 447 Wyrouboff, G., Meigen’s reaction 552 X. Xanthitane 350,500 Xanthoconite 653 Xanthophyllite 393 Xanthosiderite 529 Xenon 21,41,180 Xenotime 355-366,712 Xingu, River, analysis of water 91, 107 Y. Yakima River, analysis of water 85 Yamasaki, W., piedmontite 407 Yamashita, Y., and Majima, M., melting points of minerals 292 Yeates, W. S., copper pseudomorphs 656 Yellowstone National Park, analyses of wa- ters 79,193,194,196 spring deposits 203, 205, 206, 207, 208 \ Yellowstonose 453 Yeneseisk, Siberia, saline lakes 170 Yogoite 452 Young, A. A., enlargement of quartz grains.. 538 Young, B. R., analcite diabase 371 Young, G. J., salines of Great Basin 236 Young, G. See Irvine, R. Ytterbium 21,711 Yttrialite 712 Yttrium, distribution 21, 711 sources of 712 Yttrocerite 336 Yttrocrasite 712 Yukon River, analysis of water 86 Z. Zaleski, S. S., cited 104 Zalinski, E . R., thuringite and chamosite 575 Page. Zaloziecki, R., formation of petroleum 731, 735 mirabilite 227 Zaloziecki, R., and Hausmann, J., Rouma- nian petroleum 717 Zaloziecki, R., and Klarfold, II., optical ac- tivity of petroleum 735 Zambonini, F., age of earth 318 Akermanite 398 gehlenite group 399 molybdosodalite 373 pseudonephelite 372 sublimed galena 271 Zaracristi, , Colombian nitrates 256 Zaratite 694 Zeiller, R., compression of peat 760 paper coal 748 Zelinsky, N., cited Ill Zemduzny, S., eutectics 423 Zemjatschensky, P. A., hydrogoethite 529 Zem-zem, analysis of water 197 Zeolites 210,211,416 Zepharovichite 520 Zietrisikite 719 Zillaruello, A., Chilean nitrates 255 Zilliacus, A. , analysis by 445 Zinc, distribution 21 in river water 189 in sea water 121 ores of 669-676 Zincaluminite 672 Zincite 672,676 Zinkenite 678 Zinnwaldite 392 Zircon 274,352-354,711 Zircon pyroxenes 383,711 Zirconiferous sandstone 354 Zirconium, distribution 22 sources of 711 Zitowitsch, , gases in coal 757 Zoisite 406-408, 595, 601 Zoisite rocks 596 Zorgite 676 Zschimmer, E ., alteration of micas 396 Zuber, R., origin of petroleum 730 Zulkowski, K., andalusite group 409 Zurich, Lake of, analysis of water 97 O . RTMENT OF THE INTERIOR Franklin K. Lane, Secretary United States Geological Survey George Otis Smith, Director — - - ■ . — BULLETIN 616 ’c. m THE DATA OF GEOCHEMISTRY THIRD EDITION W3 BY FRANK WIGGLESWORTH CLARKE ■■ WASHINGTON GOVERNMENT PRINTING OFFICE 1916