LIBRARY Connecticut Agricultural College Vol. Class No. Cost 1^ . £. Ji^o JLcL^^M^ RRITL 5490191T 1889 c. 1 S.Ni . lEXT-BOOK OF MIMERALOOV 005 1 fe 3 T1S3 001351 - ^ iH o -• vO y MINERALOGY AND MINING. Mine Accidents — Ventilation — Ore Dressing, Etc. DESCRIPTIVE MINERALOGY. DANA. Comprising the most recent Discoveries. Fifth edition. Al- most entirely re-written and greatly enlarged. Containing nearly 900 pages 8vo, and upwards of 600 wood engrav- ings. By Prof. J. D. Dana, aided by Prof. Geo. J. Brush. In- • eluding Appendices by Profs. Brush and E. S. Dana, com- pleting the work up to 1882 8vo, cloth, $10 00 "We have used a good many works on Mineralogy, but have met with none that begin to compare with this in fullness of plan, detail, and execu- tion." — American Journal of Mining. THIRD APPENDIX TO DITTO. DANA. Bringing the work down to 1883. By E.S. Dana. 8vo, limp cloth, 150 APPENDICES TO DESCRIPTIVE MINERALOGY, FIRST, SECOND, AND THIRD. BRUSH, Completing the work to 1882. By Prof. Geo. J. Brush and DANA, E. S. Dana 8vo, limp cloth, 2 00 MANUAL OF MINERALOGY AND PETROGRAPHY. DANA. Containing the Elements of the Science of JMinerals and Rocks, for the use of the Practical Mineralogist and Geologist, and for Instruction in Schools and Colleges. By Jas. D. Dana, LL.D. Fourth edition. Revised throughout and enlarged. Illustrated with numerous woodcuts. 1887 12mo, cloth, 2 00 " The present issue is the 15th of the revised edition, the sale having reached nearly 15,000 copies. This is conclusive evidence of its value as a text-book, and for practical purposes." A TEXT-BOOK OF MINERALOGY. DANA. Based upon the System of Mineralogy of Prof. J. D. Dana. Embracing an extended Treatise on Crystallography and Physical Mineralogy. By Edw. S. Dana, Curator of Miner- alogy, Yale College. With upwards of 800 woodcuts and one colored plate. Revised and enlarged edition. 1883. 8vo, cloth, 3 50 MANUAL OF DETERMINATIVE MINERALOGY. BRUSH. With au Introduction on Blow-Pipe Analysis, (constituting DANA. the Determinative Part of Dana's Mineralogy). By Prof. Geo. J. Brush. Third edition, translated into the new system. 8vo, cloth, 3 50 INSTRUCTIONS FOR THE DETERMINATION OF ROCK-FORMING MINERALS. HUSSAK. By Dr. Eugen Hussak, Privat Doceat in the University of SMITH. Grau. Translated from the German by Erastus G. Smith, Prof, of Chemistry and Mineralogy, Beloit College. With 1G3 plates 8vo, cloth, 2 00 A MANUAL OF LITHOLOGY. WILLIAMS. A practical work, intended to enable the student to classify at sight the more common species. By Edward H. Williams, Jr., Professor of Mining Engineering at Lehigh University, Pa 18mo, cloth, 1 25 A CATALOGUE OF MINERALS, CHESTER. Alphabetically arranged, with their Chemical Composition and Synonyms. By Prof. A. H. Chester, Hamilton College. 8vo, cloth, 1 25 COMSTOCK LODE; ITS FORMATION AND HIS- TORY. CHURCH. Illustrated with six plates and thirteen figures. By Prof. John A. Church, E.M., Ph.D 4to, cloth, $5 00 THE COAL-MINES OP THE WESTERN COAST OP THE UNITED STATES. GOODYEAR. By W. A. Goodyear 12mo, cloth, 2 50 THE PRACTICE OP ORE DRESSING IN EUROPE, KUNHARDT. By W. B. Kunhardt, Mining Engineer 8vo, cloth, 1 60 ACCIDENTS IN MINES, SAWYER. Arising from the Falls of Roofs and Slides. Their Causes and the Means of Diminishing their Frequency, with Detailed Sections of Workable Seams and an Account of the System of Timbering in vogue in StaflTordshire Coal-field, and Appli- cable elsewhere. By Arthur R. Sawyer, of the Royal School of Mines, and one of H. M. Inspectors of Mines. With over 800 figures of illustrations, partly printed in colors. 8vo, cloth, 7 00 "This book should be in the possession of every person connected with the mining of coal." — Mining Herald. " This book should be not only interesting to miners, but be found pro- lific of valuable treats and advice." — Engineering News. PRACTICAL MINE VENTILATION. WILSON. For the Use of Mining Engineers, Students, and Practical Men. With plates. By Eugene B. Wilson, M.E. ..16mo, cloth, 1 ?5 " It is the best book in the English language on the subject."— Thos. DAVts, Derringer, Pa. " We recommend it heartily to our mining community."— Colliery Ouar- dian, London. RESOURCES OP SOUTHWEST VIRGINIA. 30YD. A book not only for the general reader, but for Geologists, Mineralogists, Engineers, and Scientists, written in a popular style, and particularly suited to citizens of Virginia. By C. R. Boyd, M.E. Illustrated by a fine topographical, geological, and geographical map, plates, etc 8vo, cloth, 3 00 DITTO. Third edition, on lighter paper 8vo. cloth, 2 50 THE MODERN HIGH EXPLOSIV|3S— NITRO-GLYC- ERINE AND DYNAMITE. EISSLER. Their Manufacture, their Use, and their Application to Min- ing and Military Engineering; Pyroxyline or Gun Cotton, the Fulminates, Picrates, and Chlorates; also, the Chemistry and Analysis of the Elementary Bodies which enter into the Manufacture of the principal Nitro-Compounds. By Manuel Eissler, Mining Engineer. With many illustrative plates. 8vo, cloth, 4 00 " This volume supplies to the enjjlneer, contractor, and the chemist pre- cisely what they previously needed with regard to the explosive forces which tht,y may bo called upon either to supply or use.'''' —Mirdtu/ Record. EXPLOSIVE COMPOUNDS AND ROCK DRILLS. DRINKER. Giving properties of Modern Explosives, Principles of Blast- ing, and descriptions and uses of the various Rock Drills and Compressors, and forming a SUPPLEMENTARY VOLUME to the first edition of DRINKER'S TUNNELING. 4to, cloth, 5 00 PUBLISHED AND FOR SALE BY JOHN WILEY & SONS, Astor Place, New York. 4t% Will be prepaid hy mail on the receipt of the price. 1 Oril>()i-lu)ii\l>ic p **t^s?^ 2 Monoilinic - liicliiiefi I)i.sp('r;siroii()( Imic-KoriTioiit ;i 1 Disjifi-sion ^ l Ntonorliiiir — t vossed T3i^^])cisiim N A TEXT-BOOK \ OF MINERALOGY. WITH AN EXTENDED TREATISE ON CRYSTALLOGRAPHY AND PHYSICAL MINERALOGY EDWARD SALISBURY DANA, CURATOR OF MINERALOGY, YALE COLLEGE. ON THE PLAN AND WITH THE CO-OPERATION PROFESSOR JAMES d!^DANA WITH UPWARDS OF Eight hundred woodcuts and ONE COLORED PLATI. NEWLY REVISED AND ENLABQED. (L5Tn Edition.) NEW YORK: JOHN WILEY & SONS, 15 ASTOR Place. 1889. Copyright bt EDWARD S. DANA 1877. Press of J. J. Little & Co* Astor Place, New York. PREFACE. The preparation of a " Text-Book of Mineralogy " was undertaken in 1868, by Prof. J. T>. Dana, immediately after the publication of the fifth edition of the System of Mineralogy. The state of his health, however, early compelled him to relinquish the work, and he was not able subsequently to resume it. Finally, after the lapse of seven years, the editorship of the volume was placed in the hands of the writer, who has endeavored to carry out the original plan. The work is intended to meet the requirements of class instruction. With this end in view the Descriptive part has been made subordinate to the more important subjects embraced under Physical Mineralogy. The Crystallography is presented after the methods of N'aumann ; his system being most easily understood by the beginner, and most convenient for giving a general knowledge of the principles of the Science. For use in calculations, however, it is much less satisfactory than the method of Miller, and a concise exposition of Miller's System has accordingly been added in the Appendix. The chapter on the Physical Characters of Min- erals has been expanded to a considerable length, but not more than was absolutely necessary in order to make clearly intelligible the methods of using the principles in the practical study of crystals. For a still fuller discussion of these subjects reference may be made to the works of Schrauf and of Groth, and for details in regard to the optical characters of mineral species to the Mineralogy of M. DesCloizeaux. The Descriptive part of the volume is an abridgment of the System of Mineralogy, and to that work the student is referred for the history of each apecies and a complete list of its synonyms ; for an enumeration of ob- served crystalline planes, and their angles ; for all published analyses ; IV PREFACE. for a fuller description of localities and methods of occurre nee, and also foi an account of many species of uncertain character, not mentioned in the following pages. A considerable number of changes and additions, how- ever, have been made in the preparation of the present work, made neces- sary by the progress in the Science, and among these are included many new species. The chemical formulas are those of modern Chemistry. The new edition of Rammelsberg's Handbuch der Mineralchemie has been often used in the preparation of the volume, and frequent references to him will be found in the text. The work has throughout been under the supervision of Prof. Dana, and all the proofs have passed under his eye. Acknowledgments are also due to Prof. G. J. Brush and Pi'of. J. P. Cooke for friendly advice on many points. PREFACE TO THE REVISED EDITION. In this Revised Edition, the chief additions are contained in four sup- plementary chapters, covering about fifty pages. Of these, two are devoted to descriptions of new instrnments and methods of research in Crystallog- raphy and Physical Mineralogy; and the others to brief descriptions of the minerals recently announced, and a concise statement of imjDortant new facts in regard to the characters or occurrence of old species. A number of new figures are introduced in illustration of these subjects. The work has been repaged ; and a new index, much more complete than the former one, has been added. >Tew Haven, January, 1883. TABLE OF CONTENTS. Introduction. F A R. T I. THYSICAL MINERALOGY. Section I. Crystallography. PAOB Descriptive Crystallograpdy 1-83 General Characters of Crystals 1 Descriptions of some of the Simpler Forms of Crystals 3 Systems of Crystallization 8 Laws with reference to the Planes of Crystals 10 I. Isometric System 14 II. Tetragonal System 25 IIL Hexagonal System 31 IV. Orthorhombic System 41 V. Monoclinic System 47 VL Triclinic System 50 Matuematical Crystallograpity 51 Methods of Calculation in General 53 Special Methods of Calculation in the different Systems 62 Measurement of the Angles of Crystals 83 Compound or Twin Crystals 88 Irregularities of Crystals 102 Crystalline Aggregates. Ill Pbeudomorphous Crystals. 113 Section I. Supplementary Chapter. Improved Instruments for the Measurement of the Angles of Crystals 115 Section II. Physical Characters of Minerals. I. Cohesion and Elasticity il9 Cleavage and Fracture 119 Hardness 120 Tenacity 121 II. Specific Gravity 123 III. Light 125 Fundamental Principles of Optics 125 Distinguishing Optical Characters of Crystals of the different Systems 135' Isometric Crystals 135- Uniaxial Crystals 136 Biaxial Crystals 144 Diaphaneity ; Color 161 Lustre 167 Vi TABLE OF CONTENTS. PAQE IV. Heat 168 V. Electricity — Magnetism 169 VI. Taste and Odor. 171 Section II. Supplementary Chapter. I. Cohesion and Elasticity 173 II, Specific Gravity 173 III. Light 1 77 Determination of Indices of Refraction 177 Polarization Instruments 178 Discussion of tbe Various Explanations offered for Observed " Optical Anoma- lies" of Crystals 185 I».A.RT II- CHEMICAL MINERALOaY. Chemical Constitution of Minerals 191 Dimorphism ; Isomorphism 199 Chemical Examination of Minerals : In the Wet Way 203 In the Dry Way ; Blowpipe Analysis 203 PART III. DESCRIPTIVE MIKERALOGT. Classification of Mineral Species 215 Description of Mineral Species 221-419 Supplementary Chapter 420-440 Appendix A. Miller's System of Crystallography 441 Appendix B. On the Drawing of Figui-es of Crystals 4C3 Appendix C. Catalogue of American Localities of Minerals 473 Appendix D. Supplementary Catalogue of American Localities of Minerals 503 Appendix E. Tables to be used in the Determination of Minerals 509 General Index 525 INTRODUCTION. The Third Kingdom of Nature, the Inorganic, embraces all sj^ccies nol organized by living growth. Unlike a plant or animal, an inorganic spe- cies is a simple chemical compound, possessing unity of chemical and physi- cal nature tliroughout, and alike in essential characters through all diversity of age or size. The Science of Mineralogy treats of those inorganic species which occur ready formed in or about the earth. It is therefore but a fragment of the Science of Inorganic nature, and it owes its separate consideration simply to convenience. The Inorganic Compounds are formed by the same forces, and on the same principles, whether produced in the laboratory of the chemist or in outdoor nature, and are strictly no more artificial in one case than in the other. Calcium carbonate of the chemical laboratory is in every character the same identical substance with calcium carbonate, or calcite, found in the rocks, and in each case is evolved by nature's operations. There is hence nothing whatever in the character of mineral species that entitles them to constitute a separate division in the natural classification of Inorganic species. The objects of Mineralogy proper are three-fold : 1, to present the true idea of each species ; 2, to exhibit the means and methods of distinguishing species, which object is however partly accomplished in the former ; 3, to make known the modes of occurrence and associations of species, and their geographical distribution. In presenting the science in this Text Book, the following order is adopted : I. Physical Mineralogy, comprising that elementary discussion with regard to the structure and form, and the physical qualities essential to a right understanding of mineral species, and their distinctions. II. Chemical and Determinative Mineralogy, presenting briefly the general characters of species considered as chemical compounds, also giving the special methods of distinguishing species, and tables constructed for this purpose. The latter subject is preceded by a few words on the use of the blow-pipe. III. Descriptive Mineralogy, comprising the classification and descrip- tions of species and their varieties. The descriptions include the physical and chemical properties of the most common and important of the minerals, Vlll INTKODUCTION. with some account also of their association and geographical distribution. The rarer species, and those of uucertain composition, are only very briefly noticed. Besides the above, there is also the department of Economic Mine) alogy, which is not here included. It treats of the uses of minerals, (1) as ores; (2) in jewelry ; and (3) in the coarser arts. The following subjects connected with minerals properly pertain to Geology : 1, Litholo- ffical geology, or Lithohgy, which treats of minerals as constituents of rocks. 2, Ghemical geology, which considers in one of its subdivisions the origin of minerals, as determined, in the light of chemistry, by the associations of species, the alterations which species are liable to, or which they are known to have undergone, and the general nature, origin, and changes of the earth's rock formations. Under chemical geology, the department which considers especially the associations of species, and the order of succession in such associations, has received the special name of the paragenesis of minerals ; while the origin of minerals or rocks through alteration, is called metamorphism or pseudomoiphism, the latter term being restricted to those cases in which the crystalline form, and sometimes also the cleavage, of a mineral is retained after the change. LITEEATUKE. For a catalogue of mineralogical works, and of periodicals, and transactions of Scientific Societies in wtiich mineralogical memoirs have been and are published, reference is made to the System of Mineralogy (180S), pp. xxxv-xlv., Appendix II. (1874), and Appendix III. ^1882). The following works, however, deserve to be mentioned, as they will be found use- ful as books of reference. In Crystallogeaphy • Naumann. Lehrbuch der reinen und angewandten Krystallographie. 2 vols., Svo. Leipzig. 1829. Kaumann. AnfangsgrUnde der Krystallographie. 2d ed., 292 pp., Svo. Leipzig, 1854. Naumann. Elemente der theoretisehen Krystallographie. 883 pp., Svo. Leipzig, 185G. Miller. A Treatise on Crystallography. Cambridge, 1839. Grailich. Lehrbuch der Krystallographie von W. H. Miller. 328 pp., Svo. Vienna, 1856. Kopp. Einleitung in die Krystallographie. 348 pp., 8 vo. Braunschweig, 1862. Von Lang. Lehrbuch der Krystallographie. 358 pp., Svo. Vienna, 1806. Qucnstedt. Grundriss der bestimmenden und rechnenden Krystallographie. Tiibingen, 1873. Rose-Sadeheclc. Elemcnte der Krystallographie. 3d ed., vol. i., 181 pp., Svo. Berlin, 1873. Vol. u., Angewandte Krystallographie. 284 pp., Svo. Berlin, 1876. Schrauf. Lehrbuch der Physikalischen Mineralogie. Vol. i., Krystallographie. 251 pp., 8vo., 1866 ; vol. ii., Die angewandte Physik der Krystalle. 426 pp. Vienna, 1868. Groth. Physikalische Krystallographie. 527 pp., Svo. Leipzig, 1876. Klein. Einleitung in die Krystallberechnung. 393 pp., Svo. Stuttgart, 1876. Mallard. Traite de Cristallographie geometrique et physique, vol. i. Paris, 1876. Bauerman, Text-Book of Systematic Mineralogy. Vol. i., 367 pp., 12mo. London, 1881. LiehiscJi. Geometrische Krystallographie. 464 pp., Svo, Leipzig, 1881. TschermaTc. Lehrbuch der Mineralogie. Lief. I., II., pp. 1-368. Vienna, 1881-82. In Physical Mineralogy the works of Schrauf (1868), and Gi-oth (1876), and TsehermaJc, titles as in the above list. Reference is also made to the works on Physics, mentioned on p. 160. In addition to these, on pp. Ill, 122, 160, 167, 171, 190, a few memoirs of especial importance on the different subjects are enumerated. In Chemical Mineralogy : Rammelsberg,. Hnndhxich der Mineral chemie, 2d ed., Leipzig, 1875. In Determinative Mineralogy, Brush, New York, 1878. In Descriptive Mineralogy : among recent works those of Brooke and Miller (2d ed. of Phillips' Min.), London, 1852; Quenstedt, 3d ed., Tubingen, 1877; Schravf, Atlas der Krystallformen, Lief. I.-V., 1871-1878 ; Grotli (Tabellarische Uebei'sicht der Mineralien, etc.), 2d ed., 1882; v. Kokscharof, Materialien zur Mineralogie Russlands, vol. i., 1865, vol. viii., 1881 ; Bes Cloizeanx, vol. i., 1862, vol. ii., Paris, 1874 ; Bana, System of Miner- alogy, 1868, App. I., 1872, App. II., 1874, App. IIL, 1882; Blum, 4th ed., 1874; Nau- mann-Zirkel, 11th ed., 1881. The following publications are devoted particularly to Mineralogy : Jahrbuch fiir Mineralogie ; G. Leonhard and H. B. Geinitz, Editors ; after 1879, E. W. Benecke, C. Klein, and H. Rosenbusch. Mineralogische Mittheilungen ; commenced 1872, G. Tschermak, Editor ; since 1878, published as the Mineralogische und Petrographische Mittheilungen. Mineralogical Magazine and Journal of the Mineralogical Society ; London, and Truro, Cornwall. Commenced 1875. Zeitschriit fiir Krystallographie ; P. Groth, Editor ; Leipzig. Commenced 1876. Bulletin de la Societe Mineralogique de France. Commenced 1878. ABBKEVIATIONS. For abbreviations of the names of INIineralogical works, of Journals, publications of Scientific Societies, etc., see System Min,, 5th ed., pp. xxxv.-xlv., App. III., p. viii. The following abbreviations are used in the Description of Species. B.B. Before the Blowpipe (p. 210). Obs. Observations on occurrence, etc. Comp. Composition. O.F. Oxidizing Flame (p. 204). DiflF. Differences, or distinctive characters. Pyr. Pyrognosties. G. Specific Gravity. Q. Ratio. Quantivalent Ratio (p. 198). Germ. German. R.F. Reducing Flame (p. 204). H. Hardness. Var. Varieties. An asterisk (*), appended to the name of a mineral species in the Descriptive part of this work, indicates that additional facts in regard to it are mentioned in the Supplementary Chapter, pp. 420 to 440, ix P^RT I. PHYSICAL MINERALOGY The grand departments of the science here considered are the following: 1. Structure. — Structure in Inorganic nature is a result of mathemati- cal syjnmetry in the action of cohesive attraction. The forms produced are reguUir solids called crystals / wiience morphology is, in the Inorganic kingdom, called ckystallology. It is the science of structure in this king- dom of nature. 2. Physical properties of Minerals, or those depending on relations to light, heat, electricity, maguetism ; on differences as to density or specific gravit}', hardness, taste, odor, etc. Crystallology is natui-ally divided into, I. Crystallography, which treats of the forms resulting from crystallization; II. Crystallogeny, which de- scribes the methods of making crystals, and discusses the theories of their origin. Only the former of these two subjects is treated of in this work SECTION I. CRYSTALLOGRAPHY. Crystallography embraces the consideration of — (1) normally formed or regular crystals ; (2) twin or compound crystals ; (3) the irregularities of crystals ; (4) crystalline aggregates ; and (5) pseudomorplious crystals. 1. General Characters of Crystals. (1) Ecternal form. — Crystals are bounded by plane surfaces, called simply planes or faces, symmetrically arranged in refer- ence to one or more diametral lines called axes. In the an- nexed figure the planes 1 and the i)lanes i are symmetrically arranged with reference to the vertical axis c g ; and also the planes of each kind with reference to the three transverse axes. (2) Constancy of angle in, the same species. — The crysta^- of any species are essentially constant in the angle of inclina.ir.i between like planes. The angle between 1 and i, in a givcii species, is always essentially the same, wherever tho crystal is found, and whether a product of nature or of the laboratory. S CRYSTALLOGRAPHY. (3) Difference of angle of different species. — The crystals of different Bpecies commonly differ in ani^les between corresponding planes. The angles of crystals are consequently a means of distinguishing species. (4) Diversity of planes. — While in the crystals of a given species there is constancy of angle between like planes, the forms of the crystals may be exceedingly diverse. The accompanying figures are examples of a few of ^/ the forms of the species zircon. There is hardly any limit to the number of forms which may occur ; yet for each the angles between like planes are essentiall}'- constant. Crystals occur of all sizes, from the merest microscopic point to a yard or more in diame- ter. A single crystal of quartz, now at Milan, is three and a quarter feet long-, and five and a half in circumference ; and its weight is estimated at eight hundred and seventy pounds. A single cavity in a vein of quartz near the Tiefen Glacier, in Switzerland, discovered in 18fi7, has afforded smoky quartz crystals weighi^ig in the aggregate about 20,000 pounds ; a considerable number of the single crystals having a weight of 200 to 250 pounds, or even more. One of the gigantic berj'ls from Acworth. New Hampshire, measures four feet in length, and two and a half in circamference; and another, at Grafton, is over four feet long, and thirty-two inches in one of its diameters, and does not weigh less than two and a half tons. Bitt the highest perfection of form and transparency are found only in crystals of small size. In its original signification the term crystal was applied only to crystals of quartz (f. 1), which the ancient philosophers believed to heicater congealed by intense cold. Hence the term, from KpvfrraWus, ice. (5) Stjimnetnj in the position of pilanes. — The planes on the crystals of au}?^ species, however numerous, are arranged in accordance with certain laws of symmetry and numerical ratio. If one of the simpler forms be taken as a primary ov fundamental form., all other planes will be secondary E lanes, or modifications of the fundamental form. It should be observed, owever, that the forms called primary and fundamental in crystallographic description, are in general merely so by assumption and for convenience of reference. (See also p. 12.) Cleavage. — Besides external s^nnmetr}' of form, crystall i^ation produces also regularity of internal structure, and often of fracture. This regular- ity of fracture, or tendency to break or cleave along certain planes, is called cleavage. The sui-face afforded by cleavage is often smooth and brilliant. The directions of cleavage are those of least cohesive force in a crystal ; it CRYSTALLOGRAPHY. B is not to be understood that the cleavage lamellae ai-e in any sense present before they ai-e made to appear by fracture. In regard to cleavage, two principles ma}' be here stated : — (a) In any species, the direction in which cleavage takes place is always parallel to some plane which either actually occurs in the crystals or mai/ exist there in accordance with the general laws which will be stated hereafter. {h) Cleavage is nniform as to ease parallel to all like planes ; that is, if it may be obtained parallel to one plane of a kind (as 1, f. 1), it may be ob- tained with equal facility parallel to each of the other planes 1 ; and will afford planes of like lustre. This is in accordance with the symmetry of crystallization. It will be evident from this that the angles between planes of like cleavage will be constaut : thus, a mass of calcite under the blow of a hammer will separate into countless rhombohedrons, each of which affords on measurement the angles 74° 55' and 105° 5'. In a shapeless mass of marble the minute grains have the same regularit\' of cleavage structure. See further, p. 119. 2. Descriptions of some of the simpler forms of Crystals. Preliminary Definitions. Angles. — In the descriptions of crystals three kinds of angles ma}- come under consideration, solid., ])lane., and interfor cial. The last are the inclinations between the faces or planes of crystals. Axes. — The crystallograjphic axes are imaginarj' lines passing tbi-ough the centre of a crystal. They are assumed as axes in order to describe, by reference to them, the relative positions of the different planes. One of the axes is called the vertical.! and the others the lateral ; the number of lateral axes is either tuoo or three. The axes have essentially the same re- lative lengths in all the crystals of a species; but those of different species often differ widely Diametral planes. — The planes in which any two axes lie are called the axial ox diametral plaiies or sections; they are the coordinate plo,Jies of an- alytical geometry. They divide the space about the centre into sectau.ts,' into eight sectants, called octants, if there are but two lateral axes, as is generalh' the case ; but into twelve sectants if there are three, as in hexa- gonal crystalline forms. Diagonal planes are either diagonal to the three axes, as those through the centre connecting diagonally opposite solid angles of a cube, oi diag- onal to two axes, and passing through the third, as those connecting diag- onallj' opposite edges of the cube. Similar planes and edges are such as are similar in position, and of like angles with reference to the axes or axial planes. Moreover, in the case of similar edges, the two planes by whose intersection the edges are formed, meet at the same angle of inclination. For example, all the planes and edges of the tetrahedron (f. 9), i-egular octahedron (f. 11), cube (f. 14), rhombic dodecahedron (f. 19), are similar. l\\ the iliombohedron \i. 16) there arc two sets of similar edges, six being obtuse and six acute. Solid angles are similar when alike in plane angles each for oach, and when formed by the meeting of planes of the same kind. A combination-edge is the edge formed by the meeting or iutersectio.i of two planes. ft CRYSTALI.OGKAPnT. Truncations, hevelments. — In a crystal, an edge or angle is said to be re- placed ^\\\c\\ the place of the edge or angle is occupied bj one or more planes ; and in the case of the replacement of an edge, the reflacing planes make parallel intersections with the including planes, that is. with the direction of the replaced edge (f. 43). A replacement of an edge or angle is a truncation when the replacing plane makes equal angles with the including planes. Thus, in f. 0, i-i truncatesi the edge between / and /. An edo-e is said, to be bevelled when it is replaced by two similar planes, that is, by planes having like inclinations to the adjoining planes. Thus, in f. 5, the edge between 3, 3, is bevelled by the two planes 3-3, 3-3, the right 3-3 and 3 having the same mutual inclination as the left 3-3 and 3. So, in f. 192, p. 43, the edge between /and /is bevelled by the planes j-2, i-2. Truncations and bevehnents of edges take place only between similar planes. Thus /, /, and 3, 3, are similar planes in fig. 5. The edge i|i might bo truncated or bevelled, for the same reason ; but not the edge between 1 and 7, since 1 and I are dissimilar planes. A zone is a series of planes in which the combination-edges or mutual intersections axe parallel. Thus, in fig. 3. the planes 1, 3, /make a vertical zone; so in f. 8, the planes between 1 and i-i make a zone, and this zone actually continues above and below, around the crystal ; in f. 5, the planes 3, 3-3, 3-3, 3 are in one zone ; and ^-^, 7, i-i, I, in another. On the true meaning of zones, see p. 53. The above explanations are preliminary to the descriptions of the forms of all crystals. A. FOKMS CONTAINED UNDER FOUR ^^ EQUAL TRIANGULAR PLANES. — A. Regu- lar tetrahedron, (f. 'J). Edges six ; solid angles four. Faces eqnilaternl trian- gles, and plane angles therefore 60°. Interfacial angles 70° 31' 44". Named from TerpaKi'i, four times, and ehpa, face 2. Sphenoid {J. lO). Faces isosceles triangles, not equilateral. Plane and interfacial angles varying ; the latter of two kinds, {a) two terminal, {b) four lateral. Xamed from (T^t]v, a wedge. B. — Forms contained under eight triangular planes. — The solids here included are called octahedrons, from oktuki^;, eight times,^ and eBpa, face. They have twelve edges ; and six solid angles. One of the axes, when they'dilfer in length, is made the vertical axis ; and the others are the lateral axes. The solid angles at the extremities of the vertical axes are the vertical or terminal solid a'ngles ; the other four are the lateral. The four edges meeting in the apex of the terminal solid angle are the terminal edges-; the others, the lateral or basal edges. i. Regxdar Octahedron {i.\V). Faces equilateral triangles. Interfacial angles 109° 28' 16" ; angle between the planes over the apex of a solid angle 70*=' 31' 44" ; angle between edges over a solid angle 90°. The three axes are equal, and hence either may be made the vertical. Lines connect- ing the cent-es of opposite faces arc called the octahedral or trigonal inter- CRYSTALLOGRAPHY. axes; ami those connecting the centres of opposite edges the <^6'<:?^Ci?^<;i/'aI or rhombic inter axes. 2. Square Octahedron (f. 12, f. 12a). Faces equal isosceles triangles, not equilateral. The four terminal edges are equal and similar; and sc also the four lateral. 12a The lateral axes are equal; the vertical axis may be longer or shorter than the lateral. 3. The rhomlnc octahedron (f. 13) differs from the square octahedron in having a rhombic base, and consequently the three axes are unequal. The basal edges are equal and similar ; but, owing to the nnequal lengths of the lateral axes, the terminal edges are of tM-o kinds, two being shorter and more obtuse than the other two. C. — Forms contaiked undek six equal flaxes. — The forms here in- cluded have the planes parallelograms ; the edges are twelve in number and equal ; the solid angles eight. 1. Cuhe (f, 14). Faces equal squares, and plane angles therefore 90°. The twelve edges similar as well as equal ; the eight solid angles similar and equal. Interfacial angles 90°. The tliree axes equal and intersecting at right angles. Lines connecting the apices of the solid angles are the octahedral or tri- gonal interaxes, and those connecting the centres of opposite edges the dodecahedral qy rhomlnc inter axes. If the cubic axi-s (=edge of the cube) = 1, then the dodecahedral interaxes = j/2 =1.41421 ; and the octahedral interaxes = \/Z — 1.73205. And if the dodecahedral axis = 1, then the octahedral = 1.224745. 14 TH If a cube is placed with the apex of one angle vertically over that diagonally opposite, that Is, with an octahedral interaxis vertical, the parts are all symmetrically arrang-ed around fcnia vertical axis. In this position (f. \h) the cube has three planes inclined toward one apex, and three toward the other ; it has three terminal edges meeting at each apex ; and six late- ral edges situated symmetrically, but in a zigzag, around the vertical axis. If lines are drawn connecting the centres of the opposite lateral edges, and these are taken as the lateral axes, the lateral axes, three in number, will lie in a plane at right angles to the vertical, and will inter.sect at the centre at angles of fiO^. The cube placed in this position would then have 6 CEYSTALLOGRAPnT. one vertical and three equal lateral axes ; and as the lateral axss coiTef-jiond to the dodeca hedral interaxes of a cube, the ratio of a lateral axis to the vertical is 1 : 1.224745. 2. lLhomhohedivu{i. IQiolS). Faces equal rlioiubs. The twelve edges of two kinds; six obtuse, and six acute. Solid angles of two kinds ; two Bvmnietrical, consisting each of tliree equal plane angles ; the other six un- Byninietrical, the plane angles enclosing them being of two kinds. The rhonibohedron resembles a cul)e that has been either shortened, or lengthened, in the direction of one of the octahedral axes, the former mak- ing an obtuse rhombohedron, the latter an acute; and it is in position when thiss axis is vertical, the parts being situated symmetrically about this axis, as in the second position of the cube above described. In an ohtuse rhom- bohedron (f. 16, 17), the terminal solid angles are bonnded by three obtuse plane angles, and the other six, which are the lateral, by two acute and one obtuse ; the six terminal edges (three meeting at each apex) are obtuse, and the six lateral edges are acute. Conversely, in an acute rhombohedron (f. 18) the terminal angles are made up of acute plane angles, and the lateral of two obtuse and one acute ; the six terminal edges are acute, and the six lateral obtuse. The axes are a vertical, and three lateral ; the lateral axes connect the centres of opposite lateral edges and intersect at angles of 60°. The cube in the second position (f. 15) corresponds to a rhombohedron of 90°, or is intermediate between the ol)tuse and the acute series. L). — Forms contained undke twp:lve equal i'lanes. 1. UhoiiJnG Dodecaliedron (f. 19). Faces rhombs, with the ].lane angles 109° 28' 16", 70° 31' 44". Edges twenty-four, all similar; interfacial angle over each edge 120°. Solid angles of two kinds : {a) six acute tetrahedral, being formed of four acute plane angles; and (i) eight obtnse trihedral, being formed of three obtuse plane angles. Angle between planes over apex of tetrahedral solid angle, 90° ; angle between edges over the same 109° 28' 16". The axes three, equal, rectangular, and therefore identical with those of the regular octahedi'on and cube. The dodecahedral interaxes connect the centres of opposite faces ; and the octahedral the apices of the trihedral solid angles. Kamed from ScldSeKa tvjelve, and eSpa, face. 2. Pyi'mrddal dodecahedron^ or Quartzoid. (Called also Dihexagonal Pyramid, Isosceles Dodecahedron.) Faces isosceles triangles, and arranged in two pyramids placed base to base (f. 20). Edges of two kinds: twelve equal terminal^ and six equal hasal,' axes, a vertical differ- ing in length in different species; and three lateral, equal, situated in a plane at right angles to the vertical, and in- tersecting one another at angles of 60°, as in the rhombo- hedron. E. — Prisms. — Prismatic forms consist of at least two seta of planes, the basal planes being nnlike the lateral. The bases are always equal ; and the lateral planes parallel(.>grams. The vertical axis is unequal to the lateral, {a) TJiree-sided, prism. A right (or erect) prism, havijig its bases equal equilateral triangles, {h) Foiir-nded prisms. Four sided prisms are either right (erect), or ol)liqne, the former having the vertical axis CRY8TALLOGKAPHY. at right angles to the base or to the plane of the lateral axes, and the lattci ohlioKe. ]. Square or Tetragonal Prism {t 21, 22V Base a square; lateral planes equ<»l. Edi^es of two Idnds : {a) eight basal, equal, each contained between the base and a lateral plane ; {h) fo\n- lateral, contained between the equal lateral ])lanes. Interfacial angles all 90% plane angles 90°. Solid angles eight, of one kind. Axes : a vertical, differing in length in dliferent species, and longer or shorter than the lateral ; two lateral, equal, at right ano-les to one another and to the vertical, and connecting either the centres of ''opposite lateral planes (f. 21) or edges (f. 22). The cube is a square prism with the vertical axis equal to the lateral. 23 24 ^\ ^ i 9 i ^ i ii u ^^ 2. Right Rhornhic Prism (f. 23). Base a rhomb ; lateral planes equal parallelograms. Edges of three kinds : {a) eight basal, equal, and rectan- gular as in the preceding form ; (J) two lateral, obtuse; and (c) two lateral, acute. Solid angles of two kinds ; («) obtuse at the extremities of the ob tuse edge, and {V) acute at the extremities of the acute edge. Axes rect- angular, unequal ; a vertical ; a longer lateral, the maorodiagonal axis (named from /j.dKpo) four basal acute ; (c) two lateral ob- tuse : {d) two lateral acute. The prism is in position when placed with the clinodiagoJial section \'ertical. Figs. 27 and 28 show the doubly oblique, or ohlique rhomhoidal ])rism, in which all tlie axes, and hence all the axial sections, are oblique to each CRTSTALLOGKAPHT. Other. All these cases will receive farther attention i]i the description of actual crystalline forms. 26 A "^ A ' ri; ■^ ^-- V 28 /I v/ ■ /^ iv ^J^.l 29 30 ^^ /: U, j A \ V i; ; •12"^ > / The prisms (in f. 21, 2i, 26, 28) in which the planes are parallel to the three diametral sections, are sometimes called diametral prisms. This term also evidently includes the cube. The planes whicJi form these diametral prisms are often called j)inaGoids. The terminal plane is the basal pinacoid, or simply base ; also, in f. 24 the plane (lettered i-\) parallel to the macrodiagonal section is called the macrojpinacoid^ and the plane (i-i) parallel to the bi-achydiagonal the hraehypinacoid. In f . 26 the plane {i-t) parallel the to orthodiagonal section is called the orthojpinacoidy and the plane {%-%) parallel to the clinodiagonal section the cliiiojpiiiacoid. The word^J)^';^«C'9^6/is from the Greek iriva^^ a board. (c). Six-sided Pkism. — The Hexagonal prism. Base an equilateral hexagon. Edges of two kinds: {a) twelve basal, equal and simihii-, {h) six lateral, equal and similar ; interfacial angle over the former 90°, over the latter 120°. Solid angles, twelve, similar. Axes: a vertical, of different length in different species ; three late- ral equal, intersectino; at angles of 60°, as in th{> rhombohedron, and the dihexagonal ])yramid or quartzoid, connecting the centres either of the lateral edges (f . 29), or lateral faces (f . 30). 3. Systems of Cktstalltzation. The sj'stems of crystallization are based on the mathematical relations of the forms ; the axes are lines assumed in order to exhibit these relations, they mark the degree of symmetry which belongs to each group of forms, and which is in fact the fundamental distiuction between them. Tiie num- ber of axes, as has been stated, is either three or four — the number being four when there are three lateral axes, as occurs only in hexagonal forms. Among the forms with three axes, all possible conditions of tlie axes exist both as to relative lengths and inclinations ; that is, there are (as has beeu exemplified in the forms which have been described), (A) among ortho- metric kinds, or those with rectangular axial intersections ; {a) the three axes equal ; (b) two equal, and the other longer or shorter than the two ; (c) the three unequal ; and (B) among clinometriG kinds, one or more of the intersections may be oblique (in all of these the three axes are unequal). The systems are then as follows : A, Axes three ; orthometric. 1. Isometric System. — Axes dron, rhombic dodecahedron equa". Examples, cube, regula»* octahe CBYSTALLOGKAPHT. 9 2. Tetragonal System. — Lateral axes equal ; the vertical a varying axis Kx., square prism, square octahedron. 3. (^RTiioKiioMBic System. — Axes unequal. Ex., right rhombic prism, rectangular prism, rliombic octahedron. B. Axes three ; clinometric. 1. MoNocLiNic System. — Axes unequal ; one of the axial intersection oblique, the other two rectangular. Ex., the oblique prisms (f. 25, 26). 2. Triclinic System. — Axes unequal ; three of the axial intersections ob' lique. Ex., oblique rhomboid al prism (f. 27, 28). 0. Axes four. — Hexagonal System. — Three lateral axes equal, intersect- ing at angles of 00°. The vertical axis of variable length. Example, hexagonal prisms (f. 29, 30). The so-called Diclinic system (two oblique axes) is not known to occur, for the single sub- Btance, an artificial salt, supi^osed to crystallize in this system has been shown by von Zepha- rovich to be triclinic. Moreover, von Lang, Quenstedt, and others have shown mathemati- cally that there can be only six distinct systems. The six systems may also be arranged in the following groups : 1. Isometric (from tao<;^ equal, and fxerpov, ineanure), the axes being all equal ; including : I. Isometric System. 2. Isodiametric, the lateral axes or diameters being equal; including: II. Tetragonal System ; III. Hexagonal System. 3. Anisometric (from dviao^, unequal,, etc.), the axes being unequal ; in- cluding : lY. Orthorhombio System; V. Monoolinic System ; vl. Tri- clinic System. A fiu'thcr study of these different systems will show that in group 1 the crystals are formed or developed alike in all three axial directions; in group 2 the development is alike in the several lateral directions, but un- like vertically ; and in groujD 3 the crystals are formed unlike in all thi'ee directions. Tliese distinctions are of the highest impoi'tance in relation to the physical characters of minerals, especially their optical properties, and are often referred to beyond. The numbers (in Roman numerals) here connected with the names of the system are often used in place of the names in the course of this Treatise. The systems of crystallization have been variously named by different authors, as follows : 1. IsoMKTUic. Tensular of Mobs and Haidinger ; Isometric of Hausmann ; TexsertU of Nau- maun ; liegulm-'oi. Weiss and Rose ; Cubic of Dufrenoy, Miller, DesCloizeaux; Monometric of the earlier editions of Dana's System of Mineralogy. 2. Tetk.vgonal. Pyramidal of Mohs ; Viergliedriege, or ZtDei-und-einoxige, of Weiss; Tetragonnl of Naumann ; Mo nodi metric of Hausmann ; Quadratic of von Kobell ; Dimctric of early editions of Dana's System. 8. He.vagonal. Bhombohedral oi Mohs ] BechBgliedvige, oj: Ifrd-und-einaxige o£^eiss; Uexagoiuil of Naumann ; ADmotritnetric of Hausmann. 4. "OuTUOKHOMisic. Prismatic, or Orthotype, of Mohs; Ein-und-einaxige of Weiss; Hhonibic and Anisometric oi Naumann; I'rimetric^ud Ort/tor/iombic ot Hausmann; Trim-t- rie of earlier editions of Dana's System. 5. MoNOCLTNic. Hemipnsmiitic and Tlemiorthotype of Mohs; Zioci-iind-eingliederige of Weiss; Monoclinohrdial of Naumann ; Clinorhombic of v. Kobell, Hausmann, Des Cloizeaux; Augitie of Haidinger ; Oblique of Miller; Monosymmetric of Groth. 6. TRrci-iNic. Tetarto-pris7natic otM.oh.%\ Ein-und-einf/liederigc of VfeA^a ; Triclinohcdra\ of Naumann ; Clinorhomboidal of v. Kobell ; Aiiortliic of Haidinger and Miller ; Anorthic^ 01 J^oubly Obllq ue, of Des Cloizeaux ; Asymmetric, of Groth. 10 CRrSTALLOGEAPHT. 4. Laws with reference to the planes of Crystai,8. The. laws with reference to the positions of the planes of crystals are two; first, the law of simple mathematical ratio ^ secondly, ^Ae Za-w; af symmeti'y. 1, The Law op simple Mathematical Ratio. The crystall() from the outlines of the faces of the various forms, which have been prepared by various authoi's. Models cut in hard wood representing the actual forms of the various mineral species are very valuable, when accurately made. They not only show the relations of different planes, but may also be advantageously used to give the student practice in the mathematical cal- culations of the axes and parameters, the angles being measured by him as on an actual crystal. Such models have the advantage of being of convenient size, and symraeMcal ly formed, which are conditions not often realized in the crystals furnished by nature. 2. Law op Symmetry. The symmetiy of crystals ia based upon the law that either : CEYSTALLOGEAPHT. 13 /. All parts of a crystal similar in position with reference to the o.'^eA are similar in planes or modification^ or II. Each half of the similar parts of a crystal^ alternate or syminetri- cal in position or relation to the other half may he alone similar in its 'planes or modifications. The forms resulting according to the first method are termed holohe- dral forms, from oXo^.^ all, eSpa, face ; and those according to tlie second, hemihedral, from rj^iavi, half According to the haw of full or holohedral symmetry, each sectant in one of the rectangular systems {a) should have the same planes both as to num- ber and kind ; and {b) whatever the kinds, in each sectant there should be as many of each kind as are geometrically possible. But in hemihedrism,^ either (a) planes of a kind occur only in half of the sectants ; or else {b) half the full number occur in all the sectants. In the isometric system, for example, if one solid angle of a cube has upon it a plane eqvu^lly inclined to the diametral sections, so will each of the other angles (or sectants) (f. 39-42). If one of the twelve edges of the cube has a plane equally inclined to the enclosing cubic faces (or diametral planes) the others will have the same (f. 43-40). Again, one of the solid angles of a cube being replaced by six planes, as in f. 70, this law requires that the same six planes should appear on all the other solid angles. But under the law of hemihedrism these planes may occur on half the solid angles of the cube, and .not on the other half, as in f. 87, or half the full number of planes may occur on all the angles, as in f. 101. This subject is further elucidated in the discussion of the hemihedral forms belonging to each system of crystallization. Hemihedeism is of various kinds : 1. Holomorphic, in w^hich the occuring planes pertain equally to both the upper and lower (or opposite) ranges of sectants, as in all ordinai-y hemi- hedral forms. 2. Ilemimorphic, in which tlie planes pertain to either the upper or the lower range, and not to both, and hence the planes are only half enouo-h of the kind to enclose a space, whence the term hemimorphic, from rjij.ir),form. The holomorphic forms may be either : A. Ilemiholohedral, half the sectants having the full number of planes, or B. Holohemihedral, all the sectants having half the whole number of planes. Again, as to the relative positions of the sectants containing the planes, the forms may be : a. Vertically-direct, in which the sectants of the upper and of the lower ranges are alternate, but the upper not alternate with reference to the lower, 14 CRYSTALLOGRAPHY. and, accordingly, each plane above is in the same vertical zone with a lika plane below ; as in forms described on pp. 34, 35. b. Vertically -alternate, in which the sectants of the upper and lowei ranges are alternate, and also the upper «/' 1, 7i = m. 3. m : 1 : 1 [m] when m > 1, n =1. 4. 1:1:1 [1] when ?n and w = 1. 5. CO : n : 1 [i-n] when m =: cc , 71 > 1. 6. 00 : 1 : 1 ^{j when m = cc , n = 1. 7. CO : CO : 1 [/Z'] when m, and ^ =r 00 . ISOMETRIC SYSTEM. 15 m-n for m : n : 1. These symbols are the same as those of Naumann, except that he wrote X instead of i for infinity, and introduced also the letter G (octahedron) as the sign of tha system ; so n of his system. = H; 0—1 ; oo 0=i ; 7n 0=m ; in in—m-m, oo n=i-n, and 7)1 u—m-n. Each of these expressions, appearing at first sight possibly a little obscure, may be translated into simple language. Cube. — The cube with the symbol oo : oo : 1, is composed of planes each one of which is parallel to two of the axes, and meets the third at its unit point (see f . 36). It is evident that there are six such planes, one at each extremity of the three axes, and the figure or crystal which is enclosed by these six planes lias already been described (p. 5) as the cube (f. 38). Octahedron. — The symbol 1:1:1 comprises all those planes which meet the three axes at the same distance, that is, cut off the nnit length of each. It is evident that tliere must be eight such planes, one in each octant, and they together form the regular octahedron (f. 42), which has already been described, p. 4. Dodecahedron. — The symbol oo : 1 : 1 includes those planes which inter- cept two of the axes at the same nnit distance, and are parallel to tliG third. There can be twelve planes answering to these conditions, and they form together the dodecahedron (f . 45, see also p. 6). These three forms, the cube, octahedron, and dodecahedron, are those most commonly occurring in this system, and it is important that their rela- tion should be thoroughly understood. The transitions between these forms, as thev modify one another, are exhibited in the followino; fio^ures : 38 39 40 41 42 Figs. 38 and 42 represent the cube and octahedron, and 39, 40, 41, the intermediate forms. Slicing off from tliu eight angles of a cube piece after piece, such that the planes made are equally inclined to H^ or the cubic faces, the cube is finally converted into the regular octahedron ; and the last disappearing point of each face of the cube is the apex of each solid angle* of the octahedron. The axes of the former, therefore, of necessity conned the apices of the solid angles of the latter. The form in f. 40 is called a cuho-octahedron. //A 1=125° 15' 52". If the twelve ed^es of the cube are truncated (for all will be truncated if one is) it affords the form in f. 43 ; then that of f. 44 : then the doJcralio- 16 CRTST A LLOGRA PHT. droii, f. 45 ; the axes of the cube becoming, in the transition, the axes con necting the tetrahedral solid angles of the dodecahedi'on \ II h i = 135". If t])e twelve edges of: the octahedron (f. 42) are truncated, the form in f. 47 nisults ; and by continuing the replacement, tinally the dodecahedron again is formed (f. 45). 1 A * = 144° 44' S". The last point of the face of' the octahedron, as it disappears, is the apex of the trihedral solid angle of tlie dodecahedron. These forms are thus mutually derivable. The process may be reversed, the cube beino- derivable from the dodecahedron by the truncation of the tetrahedral solid angles of the latter (compare in succession f. 45, 44, 43, 38) ; and the octahedron by the truncation of the trihedral solid angles (compare f. 45, 47, 42). These reinarks are impoi-tant as showing the rela- tions between these forms, though it is of course not intended to be under- stood that they are in any sense derived from each other in this manner in nature. The three axes (or cubic axes) connect the centres of opposite faces in the cube ; the apices of opposite solid angles in the octahedron; the apices of opposite tetrahedral solid angles in the dodecahedron. The eight trigonal or octahedral intei-axes connect the centres of opposite faces in the octahedron ; the apices of opposite solid angles in the cube ; the apices of opposite trihedral solid angles in the dodecahedron. The tvielve rhomhic or dodecahedral interaxes connect the centres of op- posite faces in the dodecahedron / tlie centres of opposite edges both in the cube and the octahedron. In a vertical section, containing each of these kinds of axes, the octahe dral interaxis intersects one of the three cubic axes at the angles 54° 44' S and 125° 15' 52", and one of the dodecahedral interaxes, at the an- gles 35° 15' 52" and 144° 44' 8". There remain four other holohe- dral fornis belonging to the system as contained in the list on page 14. Trisoctahedrons. — The sy m bol m : 1 : 1 is of that solid each of whose planes meets two of the axes at the unit distance, and the third axis at some distance which is a multiple of this unit length. It will be evident, as in f. 48, that there are three such planes in each of the eight sectants, and hence the total number of planes l)y which the solid is bounded is twenty-four. The •resulting solid is called a trigonal trisoctahedron^ and one, having m=l, is shown in f. 49. 48 It will be found a very valuable practice for the student to construct the figures of th« suocessive crystalline forms in this way, laying off the proper lengths of the several axes and ISOMETRIC SYSTEM. 17 noting the points where the different planes intersect, crystals will be found in the Appendix. Further remarks on the drawing of The symbol m : m : 1 belongs to all tlie planes which meet one axis at the unit distance, and the otliers at equal distances which are multiples of the former. As seen in the preceding case, there will bo three such planes in each of the eight sectants, and the total number consequently will be twenty-four. The solid is seen in f. 50, and is called a tetragonal trisoctahedron, or a trapezohedron. Both these forms are called trisoctahedrons, from rpt?, three times, and octahedron, because in each a three-sided pyramid occupies the position of the planes of the regular octahedron, Tliey are closely related to each other ; starting with the form m '.1 : 1, if on is diminished till it equals unity, then the symbol becomes 1:1:1, that is, it has passed into the octa- hedron. If m becomes less than unity, the symbol may be, for example, -1:1:1, whicli is identical, as has been ex- plained (p. 11) with 1:2:2 (2-2), and this is the symbol of the second trisoctahedron. This explains why, in the first list comprisintr all the possible forms, 7n was in no case made less tiiau unity. ^ Trigonal-trisoctahedron. — In this foi-m the solid angles are of two kinds : the trigonal or octahedral, and the octagonal or cubic. The edges are thirty-six in number, twenty-four of one kind, forming the octahedral or trihedral solid angles, and twelve edges meeting at the extremities of the cubic axes. Each of the twenty-four planes is an. isosceles triangle. 52 In combination w^th the cube, the form 2 appears as a replacement of each of the solid angles by three planes equally inclined on the edges ; this is seen in f. 52. With the octahedron, it appears as a bevelment of its twelve edges, as shown in f. 53. It also replaces the eight trigonal solid angles of a dodecahedron by three planes inclining on the faces. The more commonlv occurring examples of this foi-m are 2 (=2 : 1 : 1), also f (=1 : 1 : 1), aiid 3 (3 : 1 : 1). Tlie J^(g^/'a^6'?^«^^risccto^(?<;7r(?/l or trapezohedron, has three kinds of solid angles : six cubic, whose truncatioiis are cubic faces (f. 5G) ; eight octahe- dral, whose truncations are octahedral faces (f. 5G) ; twelve dodecaliedral, truncated by the dodecaliedral planes (f. 60). It has forty-eight edges ; twenty-four of one kind, those of the trihedi-al or octaliedral solid angles, and the remaining twenty-four, also of one kind, meeting in the cubic solid angles. Each of the twenty-four faces is a quadrilateral. In combination with the cube it is seen in f. 55, 56, appearing as a re placement of each of the solid angles by three planes equally inclined on 2 18 CEYSTALLOGRAPITY. the faces of the cube. Figs. 56, 57, 58, 59, 60, 62, also fchow it in com biiiatiou with the octahedron and dodecaliedron. The most coininonl;y oci'iin-iugof this series is 2-2 ( = 2 : 2 : 1), f. 54 ; as seen in f. 59, it trnncatea the twentj-foar edges of the dodecahedron. On the other hand the form 54 55 56 57 58 59 60 CI 62 63 |-| wonld replace the trihedral solid angles by planes inclined on the edges, while 3-3 replaces (f. 62), the tetrahedral solid angles of the dodecahedron, by planes also inclined on the edges. Tetruhexahedron. — The symbol oo : n : 1 {i-n) belongs to all the planes which are parallel to one axis, meet a second at the nnit distance, and the third at some mnltiple of that. There are twenty-four planes which satisfy these conditions, and they form the tetrahexahedron / f. 64, 65, represent two varieties of tetrahexahedrons. It will be seen that the planes are so arranged that a sqnare pyramid corresponds to each of the six faces of the cube ; and hence the name from rerpa/ci?, four timea^ e|, six^ and ehpa^ face^it being a 4x0-faced solid. The tetrahexahedron has six tetrahe- dral solid angles and eight hexahedral or octahedral solid angles. There are twenty-four edges of one kind forming the former solid angles, and twelve edges occupying the position of the cubic edges. Each of tiie twenty-four faces is an isosceles triangle. In combination with the cube it produces a bevelment of its twelve edges, as represented in f. 64. 64 65 66 67 68 Tlie tetrahexahedron, in f. 65, lettered *-2, has the symbol qo : 2 : 1 : and that of f. Q^^, lettered ?'-3, qo : 3 : 1. Some of the other occurring kinds are those Avith the ratios, 2 : 3, 3 : 4, 4 : 5, etc., etc. The relation of the tetrahexaliedron to the octahedron is shown in f. 67 By comparing tjiis lic^nre with f. 42, it is seen that the planes 'i-2 rej lacc ISOMETKIC SYSTEM. 19 the solid angles of the octahedron by planes inclined on its edges. Its rela- tion to the dodecahedron is presented in f. GS, which is a dodecahedron (planes i being the dodecahedral planes, see f. 45) with the tetrahedral solid angles replaced by four planes inclined each on an i. The tetrahexahedron is called a Jliooroid, by Haidinger, the form being common in fluorite. It is the Tetrakishexahedron (or Pyramidenwiirfel) of Kallmann. In accordance with considerations ah-eady presented it is evident that i\ in the symbol z-;i, may always be written as a whole number, for the symbol GO : ^ : 1 is identical with co : 1 : 2. Moi-eover it is seen that when n is <» , the form passes into the cube (^ : cc : Ij, and as n diminishes and becomes unity, it passes into the dodecahedron (co : 1 : 1). TIexoctahedron. — The genei-al form rn : n includes the largest number of similar planes geometi-ically possible in this system. This symbol icquires six planes in each octant, as will be seen by a method of con- struction similar to that in f. 48, and consequently the whole solid has forty-eight planes. It is hence called a hexakisoctahedron (e^a/ci?, six tizzies, oKTco, eight, and eSpa, face, i.e., a x S-faced solid) or hexoctahedron. The form is shown in f. 69, where it will be seen that there are three d'l&er- ent kinds of edges, and three kinds of solid angles; each of the forty- eight planes is a scalene triangle. When modifying the cube it appears as six planes replacing each of the solid angles, f. 70. It replaces the eight angles of the octahedron, and the 70 V JJ form 3-f bevels the twenty-four edges of the dodecahedron (f. 71). Other liexoctahedrons, diffei-ingin their angles, may replace the six acnte solid an- gles of the dodecahedron by ei(/ht \)\anes, or the eight obtuse by six planes. The hexoctahedron of f. 60, 70, 71 is that whose pilanes have the axia. ratio 3 : f : 1. Others have the ratio 4 : 2 : 1, 2 : | : 1 (z=6 ; 4 : 3), 5 : 4 : 1 1=15 : 5 : 3), 7 : 1 : 1 (=21 : 7 : 3), etc. 72 73 Amalgam. Magnetite. 20 OKTSTALLOGRAPHT. The preceding' figures show dodecahedrons varionsly modiried. In f. 72, /, or ^, are faces of the dodecahedron ; 7/ of the cube ; 1 of the octa- hedron ; i-3 of a tetrahexahedron (f . QQ) ; 2-2 of the trapezoliedron ot f . 54 59 ; 3-f of the hexoctahedron of f. 69, 70. In f. 73, i, O, and 1 are as in f. 72 ; 3-3 is the trapezohedron of f. 61, 62 ; and 5-f (either side of 3-3) a hexoctahedron. The hexoctahedron is called the culamantoid by Ilaidinger, in alhision to its being a common form of crystals of diamond. It is the hexakisocta- hedron of Kaumann, B. Hemihedral Forms, Of the kinds of hemihedral forms mentioned on page 13, the hemiho- lohedral, in which only half of the sectants are i-epresented in the form, produces what are called inclined hemihedrons • and the holoJiemihcdral, in which all the sectants are represented by half the full number of planes, parallel hemihedrons. In the former the sectants to whicli tlic occurring planes belong are diagonally opposite to those without the same planes ; and hence no plane has anotlier opposite and pai'allel to it; on the contrary, opposite planes are oblique to one another, and hence the name of inclined hemihedrons applied to them. They are also called tetrahedral forms, the tetrahedron being the simplest form of the number, and its habit character- istic of them all ; while the latter are called injritohedral^ because observed in the species jpijrlte. The complete symbols of the inclined hemihedrons are written in the general form ^{in : n : 1), of the pai-allel hemihedrons in the foiin ^ [m : n : 1} ; also written /c(?7i : n : 1) and 7r(m :n : 1) re- spectively. a. Inclined or Tetrahedral Hemihedrons. 1. Tetrahedron^ or IT.emi- octahedron. — 1(1 : 1 : 1). As has been shown, the form 1(1 : 1 : 1) embraces eight planes, and when holohedrally developed it produces the octahedron ; in accoi-dance, liow- ever, with the law of hemihedrism, AaZ/" of the eight possible planes may 74 75 76 76a 78 80 occur in alternate octants; thus in two opposite sectants above, and the two diagonally opposite below, as shown by the shaded planes in f. TA- \i ISOMETEIC SYSTEM. 21 these four shaded plane^ are suppressed, while the other four of the octa- hedron are extended, tlie resulting form is the regular tetrahedron, f. 76. Tlie relation of the octahedron and tetrahedron maybe better understood from f. 75. If. as just remarked, the planes shaded in f. 74 are suppressed, while the others are extended, it will be seen in f. 75 that the two latter pairs intersect in edges parallel respectively to the basal edges of the octahedron, and the complete tetrahedron is the result. The axes, it is im- portant to observe, <'-onnect the middle points of the opposite edges. Further than this, since either set of four planes may go to form the solid, two tetrahedrons are evidently possible, and they may be distinguished by calling the first, f. 76, positive, and the second negative, f. 76a. These terms are of course only relative. The plus and the minus tetrahe- drons may occur in combiiuition, as in f. 79 ; a!id though there are here pre- sent the eight planes which in holohedral forms make the octahedron, and though they should happen to be equally developed so as to give the same shape, the crj'stal would still be pronounced tetrahedral, since the planes 1 and — 1 are physically different. An example of this occurs in crystals of boracite, where tlie planes of one tetrahedron are polished while those of the other are without lustre. The plane angles of the tetrahedron are 60^, and the interfacial angles 70° 31' 44". The combinations of the cube and tetrahedron are shown in f . 77 and 78, and the dodecahedron and tetrahedron in f. 80. As the octahedron results geometrically fi'om slicing off successively .the solid angles of the cube, by l^lanes of ecpial inclination pn the cubic faces, so also the tetrahedron may e made mechanically by slicing off similarly Aa^/ these solid angles. 81 83 83 84 Hemi-trisoctahedrons, |-(m : m : l)and ^{rn : 1 : 1). In the same maimer as with the tetrahedron, the form m.-7n, when hemihedral, may have half its twenty-four planes present, viz., those in the two opposite sectauts above and the alternate sectants below. When these twelve planes are extended, the others being suppressed, they form the solid represented in f. 81 ; the symbol properly being ^( m-)n\ or here i(2-2). The faces, as will be ob served, are trigonal, and the solid is sometimes called a cwproid. There is the same distinction to be made liei'e between the plus and the minus forms as with the tetrahedrons. Figs. 82, 83, 84 show combinations of -^-hiin-m) with the plus tetrahedron, the dodecahedron, and the tetrahexahedron. Bimilarly the form w, when hemihedral, according to the same principle results in the solid, f. 85. It is called the deltohedron by Ilaidinger ; it has trapezoidal faces. In f. 86, +2(f) is shown in combination with -f-|^(2-2). Here also the distinction between the plus and mmus forms is to be made in the same manner as that ali-eady explained. 22 CRYSTALLOGRAPHY. Inclined or tetrahedral Hemi-hexoctahedron \{m : n : 1). The form m-n when developed according to the law of inclined lieniihedrism, that is, when of its forty-eiglit faces, half are present, viz., all in half the whole 85 86 87 88 mimber of sectants, produces the solid seen in f. 87. There is here also a plus solid, and a minus solid, corresponding to the + and — tetrahedron. fn f. 88 it is in combination with the jDlns tetrahedron. If the same method of inclined heniihedrism be applied to the remain- ing solids of this system, the cube, dodecahedron, and teti-ahexahedron, that is, if in each case the parts in two opposite sectants above, and the two diag- onally opposite sectants l>elow, be conceived to be extended, the other half being suppressed, it will be seen that the solid reproduces itself ; the hemi- hedral form of the cube is the cube, and so of the others. The following figures represent some other combinations of these forms. 89 89a 90 Sphalerite. Sphalerite. Tetrahedrite. In f. 89, the cnproid3-3 is combined with the faces /of a dodecahedron. The form 3-3 resembles closely that of f. 81, but in its combination with the dodecahedron it does not truncate an edge of the dodecahedron, like 2-2 inf. 83. Fig. 89a contains the same planes conibined with the plus tetra- hedron, hexagonal planes 1, the minus tetrahedron, triangular planes 1, and the faces of tiie cube 7/. The presence of the plane TT facilitates the com- parison of the form with f. 55, 56, 57, p. 18, the plane 3-3 having the same position essentially with 2-2. Fig. 90 lias as its most prominent planes those of f. 81 , but the position given it is relatively to f. 81 that of the minus hemihedron ; and there are also the small planes 2-2 about the angles, which are those of the minus hemihedron, //, are planes of the cube ; 1, those of the tetrahedron; i, those of "the dodecahedron ; i-Z those of a tetrahexahedron (77, t, i-Z all holohedral) ; and |the planes of a deltohe- dron similar to f. 85, and occurring with 2-2 in £ %Q. ISOMETRIC STSrEM. 23 h. Parallel or j>y^itohedral hemihedrons. — According to tlie second la\^i of hemihedrisin. half tlie Avhole number of planes of any form may be pre- sent in all the sectants. In the resulting solids each plane has another par- allel to it. This method of hemihedrisin obviously pi'oduces distinct fonns only in those cases where there is an even number of planes in each octant. Pen.tago)ial Dodecahedron^ or Ilemi'tetra/iexahedron^ -^-(0) : n : 1). If of the twenty-four planes of the form i-n (co : n : 1), only half are present ; viz., one of each pair in the manner indicated by shading in f. 91, these being extended while the others are suppressed, the solids in f. 92 and f. 93 result. The parallelism of each pair of opposite planes will be seen in these figures. These two possible forms, seen in the figures, are distinguished by calling onoplus (arbitrarily), -f-i[«-2], and the other minus,— ■|■[^'-2]. These solids are very common in the species pyrite, and are hence caMod jji/ritoke- drons ; they are also called penragonal dodecahedrons, in allusion to their pentagonal faces. The regular dodecahedron of geometry belongs to this class, but is an imj)ossible form in nature, since for it n must have an irra- tional value, viz., -^I- — , see p. 10, 2i In combination with the cube the form +|-[^-2] is seen in f. 94 and f, 95, and in f. 96, 97, with the octahedron, and in f. 98, with the cube and octa- hedron. 91 92 93 94 96 98 Parallel hemi-hexoctahedron, ^\jn : n : 1]. When of the forty-eight planes of the form m-rij only half are present, viz., the three alternate 99 101 planes in each octant as indicated by the shading in f. 99, the solid in 1. 100 results. This solid is coWn^ dkdijdoid by Haidinger. It is also called 24 CBY STALLOGKAPHY. a dyalds-dodecaheclron. In f. 101 it is shown in combination with the cube and in f. 102 with the octahedron. Figs. 103, 104, 105, of the species pyritc, represent vurions conil)ina- tions of parallel heraihedrons with the cubic and other faces. In f. 103 there are planes of twohemi-tetrahcxahedrons (pentagonal dodecahedrons) *-2, ?-| ; and of two diploids 4-2, 3-f, along with planes of the octahedron, 1, and of the trapezohedron 2-2. In f. 104 the dominant form is the dode- cahedron, /; it has the faces of the cube, //; of the octahedron, 1 ; of the 103 Pyrite. Pyrite. Pyrite. trapezohedron, 2-2; and of the parallel hemihedrons, ^-2 and 4-2. Fig, 105 represents a map of one angle of a cube, showing at centi-e the octahe- dral face 1, and around it the faces, of the cube li, of the trapezohedron 2-2, the trigonal trisoctahedron 2, and the pai-allel hemihedrons, i-2, 2-|-, 3-|. The lixial ratio for 2-| is 2 : ^ : 1 (or 6:4:2), and for 3-^, 3 : I : 1 (or 6:3:2). Prominent distinctive characters. — The student, in order to facilitate hia study of Isometric forms in nature, should be thoroughly familiar with the following points, from the study of models or natural crystals ; (1) The isometric character of the symmetry, the planes being alike in grouping in the direction of the three axes. (2) The foiuns of the faces and solid an- gles of the octahedron, the dodecahedron, the trapezohedron 2-2, the pen- tagonal dodecahedron z-2. (3) The fact that the following are connnon an- gles in the system— 135° (=HAi); 101i° 28' (angle of octahedron), 70° 32' (ano;le in octahedron and tetrahedron) ; 120° (angle of dodecahedron); 125° 16'X=IlAl); 144° 44' (=IIa2-2== lA^); 153° -6'' (=IIA^•-2) ; 161° 34' (=11 A*-3). A list of the angles belonging to the various forms of this system ia given on p. 67. (4) Cleavage nniy be cubic, octahedral, or dodecahedi'ol / and sometimes two of these kinds, and occasionally the three, occur in the same species, but always with great diifcrence of facility between them. Galenite is an example of easy cubic cleavage ; fluoi'ite of easy octaliedral ; sphalerite (blende) of easy dodccahedral. PlCvnts of symmetry . — Thebcven kinds of solids described on pp. 15 to 19, include all the holohedral foi-ms possible in this system, as is evident from their geometrical development. In them exists the highest degree of syjn metry possible in any geometi-ical solids. In the cube, as has already been stated," all planes, solid angles, and edgea are equal and similar. The three diametral planes, passing each through two of the axes. ar(^- the chief planes of symmetry, every part of the crystal TETRAGONAL SYSTEM. 25 on one side of the plane having its eqnal and synnnetrical part on the op>po' site side. Further than this, each of the six planes passing through the diagonal edges of the cube, and consequently parallel to the dodecaiiedral planes, are also planes of synmietry. There are hence in this system ninfi planes of symmetry. IL— TETRAGONAL SYSTEM. In the Tetragonal System, there are three rectangular axes ; bnt while the two lateral axes are equal, the remaining vertical axis is either longer or shorter than they are ; there are consequently to be considered the lateral axes (a) and the vertical axis (c). The general geometiical expression for the planes of crystals becomes for this system mo : na : a, and, if this be developed in the same way as the cor- responding expression in the Isometric system, all the forms* geometrically possible are derived. 1. rao : na '. a [m-n] when m >1, n >1. 2. \ c :a : a [1] when m=:l, n=l. \ mo : a: a [ni] when m^l. n=l. 3. i c: coa : a [l-i] when m=i, n= . I mc '. cc a : a ['?/^-^] when m^l, n=l. 5. COG : a: a in when 7n=co , 71 = 1. 6. cc G : oo a i a [i-i] when m=(x> , 71= QC Y. ( (c : oott : co«) [0] when m = 0, n = l. j or Oc : a : a. In lettering the planes the abridged symbols are used; here, as before, j=oo , and the unit term is omitted as unnecessary, mc : oort : a — in-i, etc. These are the same as the symbols of Naumann, except that he wrote oo , and added P as the sign of the systems which are not isometric; 0P—O\ ca Px> —i-i \ ooP=/; co P/i—i-ti ] mPco z:zm-i ; inP — m; P—1; and mP/t.=m-ii. A. IloloJiedval Forms. Basal plane. — There are two similar planes corresponding to the sym- bol c : 00 « : 00 rt (or Og : a '. a '. a are parallel to the vertical and one of the lateral axes. There are four such planes, one at each extremity of the two lateral axes, and, in combination with the plane O, they form the square prism, which has been called the diametral prism, seen in f. 106. For the symbol cc G \ a \ a^ tlie planes are parallel to the vertical axis, * The word form has been freely used in the preceding pages ; from this point on, how- ever, it needs to be more exactly defined. In a crystallographic sense it includes all th« planes geometrically possible, neyer loss than two, which have the same general symboL 26 CKYSTALLOGBAPHT. and meet the others at equal distances. There are, as in tlie preceding case, four such planes. They form, in combination with the plane O^ that square prism which is seen in f. 107, and may be called the unit prism. Both the prisms i-i and / are alike in their degree of synnnctry. Each has four similar vertical edges, and eight similar basal edges unlikp ihe vertical. There are also in each case eight similar solid ansrles. 106 ir70~ ~-n ! 11 i' £i:' - :>' 108 —0- 1 II 110 iz' The iormi-n (go g : 7ia: a) is another prism, but in this each plane meets one of the lateral axes at the nnit distance, and the otiier at some nniltiple of its unit distance. As is evident in the accompanying horizontal section (f. 113), this general symbol requires eight similar planes, two in each quadrant, and the complete form is shown in f. 109. The sixteen basal edges are all similar ; the vertical edges are of two kinds, four axial X, and four diagonal l^(f. 109). The regular octagonal prism with eight similar ^ertical edges, each angle being 135°, is crystallographically impossible. Ill 113 i i i ! ! J • j i I 1 I i i! ! ! The planes I truncate the edges of the diametral prism i-i, as in f. 108. Similarly the planes i-i truncate the vertical edges of /. The prism i-n be- vels the edges of i-i, as in f. 110, where i-n=i-2. The relation of the two square prisms, i-i and /, may be further illus- trated by the figs. Ill and 112. In f. 112 the sections of the two prisms are shown with the dotted lines for the axes, and in f. Ill there are the two forms complete, the one (/) within the other {i-i). The unit pi-ism /is sometimes called the prism of the Jlrst series, and the prism i-i that of the second series. OctaJwdrons or Pyramids. — The forms tn-i and m both give rise to square octahedrons, corresponding to the two kinds of square prisms. In nv-i the planes are parallel to one lateral axis and meet the vertical axie at variable distances, multiples (denoted by m) of the unit length. Tlie total number of such planes, for a given value of m, is obviously eight, and TETEAGONAL SYSTEM. 27 the form is shown in f. 114 and 115. These planes replace the Lasal edges of the form shown in f. 106, and m varies in value from to go AYJien m. = the four planes above and below coincide with the two basal 114 116 117 /^^ ^^ {f\ I I phiiies; as tu increases, there arises a series, or zone, of planes, with mu tually parallel intersections (f. 116) ; and when m=rc , the octahedral planes ?)i-i coincide with tlie planes i-i. The value of m in a particular species depends upon the unit value assumed for the vertical axis g. The same form replaces the vertical angles of the prism J, as in f, 117, 119 I I 121 a a The octahedrons of the m series meet both of the lateral axes at equal distances and the vertical axis at variable distances. It is clear that the whole number of planes for this form, when the value of mis given, is also eight, one in each octant. When 7n=l the solid in f. IIS is obtained, which is sometimes called the unit octahedron. As m decreases, the octahe- drons become more and more obtuse, till m=:0, when the eight planes coin- cide with the two basal planes. As m increases from unity, on the other hand, the octahedrons or pyramids become more and more acute, and when m=Go they coincide with the prism I; this series forms another zone of planes. These octahedrons replace the basal edges in the form f. 107, as seen in f. 119, and as the octahedron is more and more developed it passes to f. 120, and finally to f. US. The same form replaces the solid angles of the form f. 106, as seen it f. 121, and this too gradually passes into f. 122 and f. 114. 28 CRYSTALLOGRAPHY. The relation of tlie octahedrons 1 and l-i {m a,ndm-i) is the same as that of tlie prisms / and i-i (com])are f. 112). Similarly, too, they are often called octahedrons (or pyramids) of the Ji?'st (m) and second {m-i) series. As will be seen in f. 123, 1-i truncates the pyramidal edges of the octahe- •lon 1, and, conversely, the edges of the octahedron %i are truncated by the octahedron 1 (f. 121:). Octagonal jW^^f^ids. — The form m-n {mc : na : a) in this system has, as in the preceding sys- tem, the highest number of similar planes which are geomefrically possible; in this case the num- ber is obviously sixteen, two in each of the eight sectauts, as in f. 125, where m=l, n=2. These sixteen similar planes together form the octagonal pyramid (strictly double pyramid) or zirconoid, f. 126. It has two kinds of terminal edges, the axial X and the diagonal Y ; the basal edges ai-e all similar. It is seen (in-n=l-2) in f. 127 in combination with the diametral prism, and in f. 128 with 1, where it bevels the vertical edires. 126 127 \JJ Other tetragonal forms are illustrated in figures 2 to 8, of zircon crystals, on p. 2; f. 8 is the most complex, and besides 3-3 shows also the related zircouoids 4-4 and 5-5. Several series of forms occur in f . 129, of vesuvianite. In the unit series of planes there are the octahedrons (or pyramids) 1,2, 3, and the prism /; in the diametral series l-i, i-i ; of octagonal prisms, «-2, i-'3 ; of zir- .;onoids 2-2, 3-3, 5-5, 4-2, f-3, the whole num- oer of planes being 154. B. Ilemihedral Forms. Among hemlhedral forms there are two divisions, as in the isometric ^^T'mmiholohedral, having the full number of planes in half the sectants (a) Vertically-alternate, or sphenoidal forms.-lhe i)lanes occur in two sectants situated in a diagonal line at one extremity, and two m the traDS- verse diagonal at the other. TETEAuONAL SYSTEM. 20 With octahedral planes i(mc : a : a) the solid is a tetrahedron (f. 130, 131) called a sj>henoid,\vii\\\\g the same relation to the square prism of 130 131 f. 106 that the regular tetrahedron has to the cube. Fig. 130 is \\\e jposHive sphenoid or +l,'"and 131 the negative, or —1. Tlie form ^{mc \ ^ a : a) is similar. Fig. 132 represents the sphenoid in combination with the prism If tlie planes of each sectant are the two of the octagonal pyramid ^(mo : na : a) (f. 126), the form is a diploid (f. 133). It is in combination with the octahedron 1-?' in f. 131:. {h) Yerficallij-direct, or the planes occuring in two o])posite sectants above, and in two on the same diagonal below. The result is a horizontal prism, or forms resembling those of the orthorhombic system. Character- izes crystals of edingtonite. (c) Yertically-ohlique. Planes occurring in two adjacent octants above, and in t\vo diagonally opposite below, producing monoclinic forms, as in a hydrous ammonium sulphate. ^ 2. Ilolohemihedral, all the sectants havinghalf the full number of planes. As the largest number of planes of a kind'is two, half the full numberjs in all cases one. Ilemihedrism may occur in the forms m-n (i. 126, 127), or zirconoids, and in the forms i-n (f. 109), or the octagonal prism. The following are the kinds : («) Vertically-direct. The occurring plane of the sectants, the right one in the upper series, and that in the same vertical zone below, as indi- cated by the shading in f. 135 ; or else the left one above, and that in the same vertical zone below, f. 136. 137 138 (h) Vertically-alternate. The occurring platie therig/d above, and that in the alternate zone below, as indicated in f. 137 ; or else the left above, and that in the alternate zone below, f. 138. As the right of the two jilanes above is in the same vertical zone with the left of the two below (supposing the lower end made the upper), the two k'inds of the first divisioii will be the rl m-n ; and the Ir m-n (in f. 136 on the angles of the prism i-i) ; and the two of the second division the rr m-n and the II mrn (in f. 13S, on the angles of the prism i~i). so CRYSTALLOGRAPHY. Tlio completed fonn for the first methods has parallel faces, and is like tlie ordinary square octahedron in shape, because the upper and lower planes beloni:; to tlie same vertical zone. But in the second it is gyroidal ,' the upper pyramid has its faces in the same vertical line with an edge of the lowei', as represented in f. 139, the form U m-n. The first of these methods occurs in octagonal prisms, pj-oducing a squai-e prism, either r i-n, or I i-n. Fig. 140 represents a com- 140 bination of the octahedron 1-?' with the n nit-octahedron 1, and two hemihedral forms, one of them Ir 1-2, the other rl 3-3. The plane 1 shows the posi- tion of the octant ; 3-3 is to the 7'ight of 1, and 1-2 to the left. In f. 141, which is a top view of a crystal of ^vernerite, tliere c/ccui'S I 3-3 large, along with r 3-3 small, indicating hemi]iedrism, and, judging from that of the allied species sarcolite, it is of the square oc- tahedral kind, rl 3 3 and Ir 3-3. Fig. 142 contains the hemihedral prism I ^-|, com- hined with the unit-octaliedron 1, and the basal plane O. Wemerite. Scheelitc. Wulfenite. Varialle elements in this system. — In the tetragonal system two ele- ments are variable, and in any given case must be decided before the rela- tions of the forms can be definitely expressed. (a) The position of the lateral axes. — These axes are equal, but there are two possible positions for them, for in a given square octahedron they may be cither diagonal or diametral ; in other words, given an octahedron, as iu f. 115, 116, the prismatic planes may be made diametral (/-/), and the octahe- dron so belong to the m-i series, or the prismatic planes may be made diag- onal, that is 7 (x) c : «^ : a), Mdien the corresponding octahedrons belong to the in series. The ratio of the lateral axes for the two cases is ob\ iously 1 : /2, or 1 : 1.4142 +. (J) The length of the vertical axis. — Among the several occurring octa- hcdi-ons, one inust be assumed as the unit, and the others referred to it. In f . 143, of zircon, the octahedron 1 is made the unit, and 1)y measur- ing the basal angle it is found mathematically, as explained later, that the length of the vertical axis is 0.85 times that of the lateral axes. The octahedron 3 has then the symbol 3c : a : a as referred to this unit. If the latter octahedron had been taken as the fun- damental form, the length of the vertical axis would have been 3 xO.85 times that of the lateral axes, and the symbol of the first plane would have been \c'. a '. a. Which form is to be taken as the unit or fundamental, that is, what length of the vertical axis c is to l>e adopted, depends upon varioua considerations. In ge ' 143 In fjeneral that form is HEXAGONAL SYSTEM. 31 assumed as fniidamental -svliich is of most common oecnrrer.ce or to which the cleavage is f)arallel ; or which best shows the morphological relationa of the given species to others related to it in chemical composition, or which gives the simplest symbols for the occurring forms of a species. Prominent characteristics of ordinary tetragonal forms. — The promi- nent distinguishing characteristics of tetragonal forms are : (1) A symme- trical arrangement of the planes in fours or eights. (2) The frequent oc- currence of a square prism diagonal to a square prism, the one making with the other an angle of ISo"^. (3) The occurrence of bevelling planes on the lateral edges of thb ^quare prism. (4) A ]-esemblancc of the octahedrons to the regular octahedron, in having a square base, but a dissimilarity in that the angles over the basal edges do not equal those over the terminal. (5) Cleavage maybe either basal, square-j)7'ismatic, or octahedral / prismatic cleavage, when existing, is alike in two directions, parallel to the lateral faces of one of the square prisms, and is always dissimilar to the basal cleav- age; the basal, or the lateral, is sometimes indistinct or wanting: the pris- matic may occur parallel to the lateral planes of both square prisms, but when so, that of one will be always unlike in facility that of the other. Planes of symmetry. — There are live planes of symmetry in the tetra- gonal system : one principal plane of symmetry normal to the vertical axis, and four others, intersecting in this axis ; these four are in two pairs, the planes of each pair normal (90°) to each other, and diagonal (45°) to those of the other. III.— HEXAGONAL SYSTEM. The Uexagonal System includes two grand divisions : 1. The IIexa- GOXAL proper, in which (1) symmetry is by sixes, and multiples of six ; (2) hemihedral forms are of the kind called vertically-direct ; and (3) cleavage and all physical characters have direct relations to the holohedral hexagonal form. 2. The RnoMBOHEDRAL, in which (1) symmetry is by threes and multi- ples of three, rhombohedral forms being hemihedral in mathematical rela- tion to the hexagonal system, and of the kind called vertically-alternate ; (2j cleavage, and many other j^hysical characters, usually pailake of the hemihedrism. While the rhonibohedron is mathematically a hemihedral form under the liexagonal system, and is properly so treated in a system of mathema- tical crystallography, it is not so genetically, or in its fundamental relaticms. Moreover, it has its own hemihedral forms, which, mider the broad hexago- nal system, are tetartohedral. The holohedral forms, all of which belong to the Hexagonal division, are here fii-st described ; and then the hemihedral forms, which include, be- sides a few under the hexagonal division, the whole of the RhumbohedraX division. A. Holohedral Forms : Hexagonal Division. The general expression for planes of this system is inc : na : a : pa, where there are to be considered the vertical axis, c, and three equal lateral axes, a. 32 CRYSTALLOGRAPHY. It is evident, however, that the position of any plane is determined by its intersections with two of the lateral axes, as its direction with the third follows directly from them, (Compare f. 146.) Consequently, in writing the symbol of any plane it is necessaiy to take into consideration only the vertical axis, and two of the lateral axes adjacent to each other. The various liok)hedral forms possible in this system are derived after the analogy of those of the tetragonal system. The parameters foi- all the lateral axes are given below for sake of comparison. It is to be noted here that in may be either < 1, or > 1 ; n'vs, always > 1 and < 2, while j[) > 2 and< 00 ; further than this it is always true that jp-. mc : na : a : {jkC) mc : 2a : a : (2(^) mc '.a'.a: {oo 1 and < 2. [m-2] when ni ^ 1, n = 2. [r/i] when 7)i ^1, n = 1. [IJ when '/n = 1, n = 1. \_i-n] when 7n = cc , 7i> 1 and < 2. [«-2J when m = cc , n=z2. [I] when m = CO , n = 1. [O] when in = 0, n — 1. The abridged symbols need no explanation beyond that which has been given on mPn=m-n ; ooF/i—i-?i, etc. p. 25; Basal 2)l(-i'^^es. — The form O=.0c : a : a includes the two basal planes bovc and below, parallel to the plane of the lateral axes. U4 145 146 Llj>l / t i 7 i'S"^ Prisms. — The form I^.cc \ a \ a compi-ises the six planes parallel to the veitical axis, and meeting the two adjoining lateral axes at ecpial' dis- tances. These six planes with the basal plane form the hexagonal unit prism, f. 144. The form ^-2 = cx)6': 2a: a includes the six planes which are parallel to the vertical axis but meet one of the lateral axes at the unit distance, and the other t%oo at double that distance. These jjlanos with the basal plane form the diametral prism, f. 145. The relations ol the two prisms 1 and /-2 are shown ni f. 146. In f. 147, it will be seen that the one. prism truncates the vertical edges of the other. The faces of the i-2 make an angle of 150° with the faces of /. These two prisms have an inti- mate connection with each other, and together form a regular twelve-sided prism, — a prism which iscrystallogra})hically impossible except as the result of the combination of these two different forms. HEXAGONAL SYSTEM. 33 The form i-2 is a special case of the general form {-,i or qo c : na : a. When n is some number less than 2, and greater than 1, there must be twc planes answering the given conditions in each sectant, and twelve in all Toe-ether tbey form the dihexagonal, or twelve-sided, prism. This prism bevels the edges of the 2)rism /, and tlie vertical edges are of two kinds, axial and diagonal Tlie vahies of n must lie between 1 and 2 ; some of the occurring forms are i-^, «-f, etc. Hexagonal pyramids^ or Quartzolds. — The symbol 1=6' \ a: a belongs to the twelve planes of the miit pyramid, f. 148, while the general form jn — nic : a '. a includes all the pyramids in this series where the length of the vertical axis is some nniltiple of the assumed unit lengtli. As in the tetragonal svstem, when m diminislies, the pyramids become more and more obtuse, and the form passes into the basal plane when m is zero; while as m increases, the pyramids become more and more acnite, and finally coincide with the prism /. These pyramids consequenth^ replace the basal edo;es between O and 7, f. 149, and with them form a vertical zone of planes. The pyramids of the m-"! series have the same relation to those of the m series, just described, that the prism i-'2 has to the prism I. They replace the basal edges between ?-2 and O (f. 145), and as the value of m varies, give rise to a series or zone of planes between these limits. The pyramids of both the fii-st {tn) and the second {m-'-l) series are well shown iu f. 150, of apatite. In the iirst series there are the pyramids ^, 1, and 2 ; and iu the second series the pyramids 1-2, 2-2, and 4-2. The cor 149 r^ / 1 h^Y^ \ ' t ^ s. 1 , x\ / 42 7 7 il V. \ ll .^ responding prisms /and «-2 are also shown, and the zones between each of them and the basal plane O are to be noticed. Attention may also be called to the fact, exemplified here, that the pyramid 2-2 truncates the ver- tical edges of the pyramid 2 ; also 1-2 truncates the vertical edges of 1; while the latter form (1) also truncates the vertical edges of |-2, as is seen in f. 147. Dihexagonal pyramids^ or Berylloids. — The general form w,c : na : a gives the largest number of similar planes possible in this system, wdiich is hei-e obviously twenty-four, that is, two iu each of the twelve sectants. These pyramids correspond to the prisms of the i-n series, and form the dihexagonal pyramids, or berylloids, as in f. 151. The berylloid has three kinds of edges : the axial edges X {i. 151, 152), connecting the apex with the extremity of one of the axes ; the diagoua] edges Y, and the basal edges Z 3 34 CRYSTALLOGRAPHY. In the upper pyramid, one of these two planes for each sectant may ba distinguished as tlie rights and the other the left^ as lettered in f. 152 ; and the same, after inverting the crystal, for those of the other pyramid. It is to l)e observed that in a given position of the form, as that of f. 151, the vight 151 152 153 154 (Y^f\ \LAJ of the npper pyramid will be over the lefi of the lower pyramid, and the reverse. Fig. 153 represents the planes of such a form m-w combined with the unit prism /, and the planes are lettered I, r, in accordance with the above. In f . 154, of a crystal of beryl, the prism / is combined with the pyramids 1, 2, 2-2, and the berylloid 3-|. B. Ilemihedral Forms. I. Yertically Direct, — The planes of the u])per range of sectants being in the same vertical zone severally with those below, {A). Hemiholohedral. — Half the sectants having the full number of planes : 1. Trigonal jpyramids. — The diametral pyramid m-2 is some- 155 times thns hemihedral, as in the annexed figure (f. 155) of a crys- tal of quartz, in which there are only three planes, 2-2 at each nxtremity, and each of those above is in the same zone with one below. The completed form would be an equilateral and symme- trical double three-sided pyramid. 2. Trigonal prisjns. — The occurrence of three out of the six planes of the prism /, or *-2, produces a three-sided prism. The prism I is thns hemihedral in tourmaline (f. 156, a top view of a crystal), and the prism ^-2 in quartz. Both these forms properly belong to the Riiombo- hedral division. 3. Ditrigonal prisms. — An hexagonal pi-ism hemihedral to the dihexago- nal prism occurs in quartz and tourmaline, the hexagonal prism sometimes having only the alternate vertical edges bevelled, as in f. 185, and f. 186, p. 40. {B). Jlolohemihedral. — All the sectants having half the full number of p.anes: 1. Hemi-dihexagonal pyramids. — Each sectant has one out of the two planes of the di hexagonal pyramid (f. 151, 153) ; this is indicated by HEXAGONAL SYSTEM. 35 the shading in f. 157. The occurring plane may be the right above and left below, or left above and right below, and the form accordingly 156 »S^2 157 158 Tourmaline. either rl m-n, or Ir m-n. Examples of the first of these occur in f. 158, representing a crystal of apatite, the planes t>(3-|), and <3'(4:-|) being of this kind. This method of hemihedrism occurs only in furms that are trne hexagonal ; it is often CiiWed j)]/?'ai7iidal heinihedrisni. II. Yertically althrxate, the planes of the upper range of sectants being in zones alternate with those below. {A) Ilemiholohednd forms, or those in which half the sectants have the full number of planes as in the RnOMBOHEDRAL DiVISIOX. 1. RhoivihoTiedr oils, and their relation to Hexagonal forms. — The rhora- bohedron is derivable from tiie hexagonal pyramid by a suppression of the alternate planes and the extension of the others. In f. 159, if the shaded planes in front and the opposite ones behind are suppressed, while the others are extended, a rhombohedron will be derived. This is further shown in f. 160, where the hexagonal pyramid is represented Avithin the rhom- bohedron. Another similar rhombohedron, complementary to this, would result from the suppression of the other alternate half of the planes. One of these rhombohedions is called minus, and the other jphis (f. 161, 162), The form in f, 118 is made up, under the rhombohedral system, of -\-R and — R (or +1 and —1) combined, as in the annexed figure (f. 163), of a crystal of quartz. Fig. 164 shows the combination of the rhombohedron with the prism /; •u f. 165 the former is more developed, and it finally passes into the cono 36 CRTSTALLOGEAPHT. plete rliombohedron, f. IGl. In f. 1G6 the rhombohedral planes occur on the alternate angles of the diagonal prism «-2. The symbol of the nnit rliombohedron as referred to the hexagonal sys- tem is ^(g : a : a), a second rhombohedron may be i(2c : a : a) and so on ; it is, however, more simple to write only +B or — i?, and +21^ or —2Ji, and so on ; or, where there is no confusion with the symbols of hexagonal forms, as 4-1. —1, and +m, — m. 163 164 16G This hemihedrisra resulting in the rliombohedron is analogous, in the alternate positions of the planes above and below, to tliat producing the tetrahedron in the isometric system. But owing to tlie fact that there are three lateral axes instead of two, the rhoml^ohcdron has its opposite faces parallel, unlike the tetrahedron. In f. 1G7 the planes i? belong to the rhombohedron +1; f to the rhomboliedron +f, having the verti- tical axis fc ; O is the basal plane, or mathematically the rliombohe- dron 0, the vertical axis being Oe. I is the hexagoual prism (X) : 1 : 1, or more properly a rhom- bohedron with an infinite axis, oo c. On the opposite side of / the planes are rhombohedral, but belong to the minus series ; —-\ has the vertical this last being complementary to H-f, and the same identical form, except that all the parts are reversed. Fig. 168, A-K represent different rliombo- hedrons of the species calcite: J., the rhombohedron 1; B,—\\ (7, — 2; Z>, — f; iS; 4 ; having respectively for the vertical axis, Ic, \c, 2c, fc, 4c, with c= 0.8543, the lat- eral axes being made equal to unity. In f. 169 the rhombohedron "2 (or 2B) is combined with —1 (or —7?), the latter truncating the terminal edges of the former. In relation to the series of + and — rhombohedrons it is important to note that, since the position of — iZi? is that of the vertical edge of +Ji, in combination with it, it truncates tl.esc " res. Similarly +^i? truncates the same edges of — ^i?, and so on. Cinnabar. 169 Calcite. HEXAGONAL SYSTEM. a? Also +R tranciates the edges of — 2i?, and —R the edges of + 2/j? (f. 169), — 2R truncates the edges of +47?, and so on. 2. Scalenohedro7is ; fonns liemihedral to the dilioxagonal jpyravvki. — Aa the rliombohedron is a hemihedral liexagonal pyi-ainid or quartzoid, so a scalenohedron is a heniiliedral dilioxagonal pyramid or bervlloid. The method of hemihedrism is similar liy the suppression of the planes oi the alternate sectants, as indicated l)y the shading in f. 170 (analogous to f. 159) aud the extension of those of the other sectants. A scalenohedron ia 170 171 172 173 174 represented in f. 171, a hexagonal double pyramid with a zig-zag basal out- line, and three kinds of edges ; the shorter terminal edge X, the longer terminal edge Y, and the basal edge Z\ the lateral axes terminate in the middle of the edges Z. There are plus and minus sealenohedrons, as there are plus and minus rhombohedrons, and they bear the same rela- tion to each other. The relations of the form to replacements of the rhom- bohedron are illustrated in the other figures. Fig. 172 repre- sents a rliombohedron (+1 or R) with its basal edges bevel- led ; and this bevelment, continued to the obliteration of the planes R, produces the scalenohedron shown by the dotted lines. The scalenohedron in f. 171, 172 has the vertical axis equal to 3c', or three times as long as that of i?, the lateral axes of both being equal ; and hence it is that the planes are lettered 1\ the 1 referring to the rliombohedron and the index ^ being the multiple that gives the value of the vertical axis of the scalenohedron. In f. I'iS there are two sealenohedrons of the same series, viz., 1', 1', combined with the rhombohedrons R (or +1) and -t-4. Fig. 174 shows the scalenohedron — 1^ combined with the rliombohedron —4 (or —47?) ; and 175, the same with the rliombohe- dron 5 (-i-5R). Other sealenohedrons replace the basal angles of a rhorabohedron by two similar planes (f. 176); or bevel the terminal edges; or replace the terminal solid angles by six planes, two to each terminal edge, or to each 3» CKYSTALLOGBAPHY. rhombohedral face ; a- id they will be relatively + or — , acccrdiDg to theij position in one or the other set of sectants, as has been exi)lained. Fig. 17V represents the top view of a crystal of tourmaline. It contains ihe rhombo- 176 Tourmaline. hedral planes, i?,f, Jg^-, — i,— |, — f, —2, along with the scalenohedrons —¥, — ^^, —^\ 1|, 1\ and also two others bevelling the terminal edges of the rhombohedron li. The scalenohedrons —1", — i', —i^, bevel the basal edges of the rhombohedron — |; and consequently the lengths of the axes are respectively 2, 3, 5 times that of the rhombohedron i, and hence, equal Ic, f c, fc. Every scalenohedron corresponds to a bevelment of the basal edges of some rhombohedron— and that particular one whose lateral edges are parallel to those of the scalenohedron. The symbols for them according;y oxo made up of the symbol of the rhombohedron and an index which expresses the relation of its vertical axis as to length to that of the rhombohedron, according to a method proposed by Naumann. (See p. 72.) Hexagonal pyramids of the m-2 or diagonal series occur in many rhombohedral species ; as f. ITS of corundum, which contains |-2(r), 4-2, -2^-2 (for 9-2 on the figure read ^§-'2, Klein), along with the rhombohedron 1, and the basal plane ; also f. 167, in which is tlie pyramid 2-2. Ilemihedral forms of the same pyramids (of the kind described on p. 34) are met with in i-hombohedral species, but only such as have also tetartohedral modifications. Ilemihedral forms of the hexagonal and dihex- Corundum. f,o,^,jjg^i prisms (p. 34) ai-ealso characteristic of some rhombohedral species, and of those that have either tetartohedral or hemimorphic modifi- Cfttions. Fig. 179 illustrates the relative positions of the zones of the H- and — rhombohedrons, and diagonal pyramids 7W-2 alternating with regions of -,- and — scalenohedrons in the scheme of the rhombohedral system. The figure is supposed to be a top view. It is similar to f. 152, p. 34, and like that contains the upper planes of the dihexagonal pyramid ; but these are divided between a jilm and a vniins scalenohedron, those planes marked + being the former, and the others ( — ) the latter. The three lateral axes are lettered each bb. The posi- tion of the + mli zone of planes (or pluK rhombohedrons) relative to the scalenohedrons is shown by the lettering +A'; of the —mli zones (or minus rhombohedrons) by —Ji. The position of the vertical zone of 7«-2, or diametral pyramidal planes, is indicated by the letter d. The order of succession, beginning irith one of the plus interaxial sectants (the one in the medial line below) and numbcri\ig it I. is as follows : HEXAGONAL SYSTEM. d» 1 (1) Plus Rcalenohedrons, or planes of the general form +»»". I. < (2) Zone of plus rhombohedrons, +mR. ( (;5) Plus scalenohedrous, or planes of the general form +m^. (4) Zone of diagonal p3'rainids, w-3. !(5> Minus scalenoheJrons, or planes of the general form — m". (0) /jone of minus rhombohedrons, —mli. (7) Minus scalouohedrons, —m". (8) Zone ot diagonal pyramids, m-2. ( (9) Plus scalenohedrous, +m'\ III. \ (10) Zone of plus rhombohedrons, +mli. ((11) Plus scalenohedrous, +m". (13) Zone of diagonal pyramids. And so on around, as the figure illustrates. In the lower pyramid the order of succession It the same ; but the pias planes are directly below the minus of the above view of the upper pyramid. The ])l>is scalenohedrous have the pyramidal edge over the +?nR section, the more obtuse of the two (or edge Y) ; and the mi/ms scalenohedrous have that edge the less obtuM (or edge X), and that over the —mU section the more obtuse (or edge Y). B. IloloJu'mihednd forms, or those in which all tlie sectauts have half the full uninberof planes (as shown by the sliadin'\ d" (4-4, 5-f, 6-f, 8-f , 3-3, the first ionv right, the last left) are examples. The upper and lower of a kind adjoin the same diametral plane, but are on opposite sides of it, and therefoi-e the three sectants containins; planes below are alternate with the three above. The solid made of these six planes (f. 184) has trapezoidal faces, and ia called a trigonotf/pe by Xauniann. The tetaitohedral planes on quartz and cinnabar have a reniai"kable con- nection with the circular polarization which is characteristic of them both, and which is further explained elsewhere (p. 142). (B) IIemhnorj)hiG forms ; the planes occurring either in the upper or the lower range of sectants and not in both. There are two kinds of forms: (1) the liemi-rhomhohedroii, and (2) the herni-scalenohedron. Fig. 186 illustrates each of tliese forms. The form R is properly hemihedral at the two extremities, its planes being very large at one, and quite small at the other. So with — |. Another rhom- boliedron, —2, occurs only at the upper extremity. Again, ^ is a hemi-scalenohedron, the upper six planes being present, but not the lower. The prism /in this figm-e is hemihedral, as explained on p. 34. It is not tetartohedral to the hexagonal system in the ordinary view. But since in a vertical zone -\-mR^ zo Ji, —viR, the qo i? may be rcgai-ded as the infinite term of either the +7nR series, or else tJie same of the —niR series; and as this view accords with the tetartohedral character of the inR series in all such crystals, it might be ranked among tetartohedral forms. point c;f view, the ditrigonal prisms in toumaline and ''rom the same OBTHORHOMBIC SYSTEM. 41 quartz are tetartohedral, since they may be regarded as either phis or luiuua tetartohedral scalenohedrons, with an inliiiite vertical axis. Variable elements. — In the liexagonal system the same elements aic vari- able as in the tetragonal (see p. 30). In other words, the position of the vertical axis is fixed, but (1) a certain length must be assumed as tlie unit in a given species, and also (2) the position of the lateral axes must be fixed, for, as in f. 144, 145, either of tlie liexagonal prisms may be made I and the other ^-2, The general characteristics of this system which the student must be acquainted with are: (1) The planes constantly occur in threes or sixes, or their multiples; (2) The frequency of the angles 120° and 150° in the prismatic series ; (3) The rhombohedral cleavage, conimou in sj^ecies be- longing to the rhombohedral division. It is also important to note that many forms apparently hexagonal really belong to the orthorhombic system, being produced by twinning parallel to the vertical prism ; e.g., the appar- ently hexagonal prisms of aragoiiite. The close relation of the two systems is spoken of elsewhere (p. 46). The planes of symmetry for the holohedral forms are analogous to those in the tetragonal system ; that is, one principal plane of symmetry normal to the vertical axis, and six others intersecting in this axis. These last belong to two sets, the planes of the one cutting each other at angles of 6C, and diagonal to those of the other. IY._0RTI10RI10MBIC SYSTEM. In the ORTHORnoMBic system the three axes are unequal c,b,d\ of these h is the vertical axis, b is made the longer of the two lateral axes, or the macrodiagonal axis, and d the shorter lateral, or brachydiagonal, axis.'^ The different occurring forms, deduced as before from the general ex- oressicm, are: 1 00 G : nh : a [i-n 00 G '.h'.na \i-n 00 C : b : a r/] 00 c : b : oo a \u\ 00 c '. cob : a \i-i\ Qg: b : a w mo : nb : a [m-n] mo : h : na [rn-n] \ mc : b : a [ni] {Gib: a [1]_ ( mc : oob : a ['/''-'?■] ( wc : b : CO a [m-i] . The abridged symbols need very little explanation additional to that given on p. 35. As before, only the essential part of the symbol is given ; m is written first, and refers in all oases to the vertical axis (c), and n refers to one of the lateral axes, whether the longer (b) or the shorter (a) is indicated by the sign placed over it, as ?l or ii. When n—-co , this is indicated by the i hitherto used, and the sign is placed over it, I, or r, with the same signi- Scation. These corrcspon I to the symbols used by Naumann, as follows: 0=OP] »-*= uopQo; i-i=ooPd6; co P/l=i-)l; mPx)=m-i; mP=m\ m-)l=mP/i, etc. * For the relation of the axes thus lettered to those of Dana's System of Mineralogy and of other auth ors, see p. 53. 42 0EY8TALL0GRAPHT. A. ITolohedral Forms. Pinacoids. — The final case mentioned in the above enumeration em braces, as before, tlie two basal planes, or basal pinacoids ; the one pre- cedini^ it includes the two planes parallel to the vertical and macrodiagona) axes ((.; and //), called the laacrojnnacoids, and the next above includes the planes ])arallel to tlie vertical and brachjdiag-onal axes (c and a), called the hraclhiiinnacouh. These tliree sets of planes together form the solid in f. 188, whicli is called the diametral pi'ism. In consequence of the ine- quality of the different pairs of jjlanes there are onl}^ four similar edges in any set; thus four similar vertical edges; four macrodiagonal basal edges, two above and two below, betwe.en O and i-% ; and simihirly four brachy- diagonal basal edges between and i-i ; the eight solid angles are all similar. 188 189 ^^ ;-o- ^ i i i ii n ^^^ Prisms. — The form cc c : b : a, or I, includes the four planes of tlie unit prism which, in combination with O, is seen in f. 187. In this case the eight basal edges are similar, being made in each case by a similar pair of pfanes O and I. Of the vertical edges there are two pairs, those at theextremity of the axis d, which are obtuse, and those at the extremity of I/, whicli are acute. Similarly, there are two sets of basal solid angles, four in each; for though each solid angle is formed by the meeting of the same three planes, the angles are different in the two cases. The form / replaces the four similar vertical edges of f. 188 ; the macro- pinacoids i-l truncate the obtuse vertical edges of the prism /, and the brachvpinacoids *-i truncate the acute vertical edges of /, as shown in f. 189. Thei-e are two other sei'ies of prisms with symbols ic c : nh : a and ■yoG : b : na. In the latter series the axis^ is nuxde the unit ; the reason for this will be obvious when the relations of the two forms ai-e explained. The prism / meets both axes a and J at their unit lengths, as in f. 187. If, now, the prismatic planes meet the longer lateral axis (h) at a greater distance, a prism is foi-med such as that in f. 190, whose symbol is *-5, or GO c : 2^ : (?. This is a macrodiago- nal prism ; and others might have the symbols *-3 (oo c : Zh : a), i-l (cc c : 4J : a), and so on, or in gei^eral i-ii. If w becomes less than unity, the case shown in f. 191 arises where the inner prism has n=^, and the symbol is4-| (co c : ^J : a), still retainijig h : a includes the four planes which are parallel to the macrodiagonal axis, and meet the vertical axis at variable distances, multiples of the unit length (see f. 34, p. 11). An example of them in combination with i-i, the brachypinacoid, is shown in f. 195. These planes are called maorodomes (see also f. 196). 195 U u 196 197 The form mc :h : cca includes four analogous planes, which differ in this respect, that they are parallel to the brachydiagonal axis, and are hence called drac/iz/domes (see f. 35, p. 11). In this case, the longer lateral axis is taken as the unit. Fig. 197 shows two such brachydomes, 1-i and 2-i, in couibination with other forms. (See also f. 198.) The word dome, used here and above, is derived from Sofirj, or domus, a house, the form resem- blmg the roof of a house. The couibination of l-i- v.-ith 14 is shown in f. 199, forming a rectangular octahedron, and in f. 200 they are shown rej^lacing the solid angles foi'med by 7 and O, as in f. 188. As either of the three directions may be made the vertical, it is evident that these domes differ from vertical prisms only in position. 44 CKYSTALLOGRAPHT. 20U The occurrence of these domes in combination with the other forms, O, t-i, i-i, 7, affords an illustration of the law of symmetry that all similar parts must be modified alike. Thus in f. 1S7, as has been shown, there are two sets of solid angles, four in each ; one set is replaced by the four planes of the form Tn-l, and if one is, all must be ; and the other set (lateral) is replaced by the four planes of the form tn-i, f. 200. Octahedrons {or Pyramids). — The sym- bol c '. h '. a (X) belongs to the nnit octahedron (f. 201). It replaces the edges between the prism 1 and the basal plane O (f . 202). It also replaces 201 903 1 ^ — . rr \ I ^-i- b—/ the eight similar solid angles of the diametral pi ism, as in f. 203. Thia is a special case of the form mc \1) \ a., in which m may have values vary- ing from to CO . Fig. 208, of sulphur, shows a zone of such planes, of the general symbol inc '.h:a, with m = oo for 7; also, 7??/=l, ra=\, ^'^^i, m=|, and finally ?n — 0, for the basal plane O. 204 206 ^^^ 207 The general form in this system, consisting of eight similar planes, may be written either mc '. nh '. a {m-n) or mc : h : na {m-ii). The relation be- tween the two is the same as that between the prisms i-r. and i-n. Thus, in f. 204, one plane of the octahedron 2c \^h '. a (2-2) is given, and also one plane of another octahedron or pyramid, whoso symbol is 26' : h : a (2). If n becomes less than unity, as -h, the plane has the symboi 2c : ^b : a (2-|). In order to avoid this use of fractions the symbol is written 4:C : b : 2a, that is, 4-2. The plane is shown in f. 205, in its two positions correspond- ing to 2g : ^h : a, and ic : b : 2a, the two helug crystallographically iden- kical. ORTHOEHOMBIC SYSTEM. 4:S Thus there are two scries of pyramidal planes : a inacrodiagonal '^n-fC\ where the shorter axis is taken as the unit, and a h7' achy diagonal (^y^-n), where the unit is the longer lateral axis; and between the two lie the unit octahedron (1) and those of the m series, just as the prisni / lies between the prisms i-n and i-n. The mac rod i agonal planes 1-5 and 2-5 are shown in f. 206 and f. 207. It is also seen in f. 207 that tlie planes 2-2, 2-i, 2-2 all make parallel intersec- tions with each other and with ^'-^, being an example of a zone where the ratios of tlie ver- tical axes are the same. Further orthorhombic forms are displayed in f. 208, of sulphur, already referred to The f nil symbol of the plane 1-S is c'.h '. 3a. B. Jlemihedral Forms. Sulphur. The heraibedral forms that have been observed are of two kinds : 1, The vertically -ohllque (p. 14), producing monocUnic forms; and 2, the hemimorj)hic^ in which the planes of the octahedrons or domes of one base have no corresponding planes at the opposite extremity. The former kind 209 210 211 llumite. Humite. Calamine. is illustrated in f. 209, of the species cbondrodite (var. humite, type 111). Fig. 210 represents tlie holohedral form of the same ; the planes f-f, 1-% 2-1, ai-e of macrodomes ; ^-i, ^-i, f-t, 4-1, of brachydomes ; and the others of various octahedi-ons, mostly in two vertical zones, the unit zone {nic : b : a), and the 1 : 2 zone (wa : 21j : a). In 1. 209 the alternate of tlic macro- domes and of the octahedral planes of the 1 : 2 zone are absent in the upper half of the form, and are present without those with which they alternate in the lower half. The crystal consequently resembles one under the monoclinic system. Datolite was formerly cited as a hemihedral orthorhombic species, but it has been found to be really monoclinic. Furthermore, ithas been recently ehown by the author, by reference to the optical properties, that the ebon 46 CRYSTALLOGRAPHY. drodite of the second and third types (see p. 327) is not orthoihombic bul monoclinic, and this mnst be true also of hnmite.* Ileniiniorphic forms characterize the species topaz and calamine. The latter (in f. 211) has only the planes of a heniic)ctahedi'on at one extremity, and planes of heraidoraes at the other. For the pyro-electric properties of snch forms, see p. 109. Variable elements. — In the orthorhombic system the lengths of the three axes are variable, thonorh their position is fixed, and after these are fixed the choice of one for tut. vertical axis mnst be arbitrai-ily made. In other words, given an orthorhombic crystal, the three rectangular directions are fixed, but two assumptions must be made which will mathematically deter- mine the length of two of the axes in terms of the third. For instance, in a crystal, if certain occurring domes are adopted as the unit planes \-% and 1-^, this will determine, the i-elative lengths of the three axes, for which two measni-ements will be necessary' ; oi*, if an occurring octahe- dron is assnmed as the unit octahedron (1,) this alone will obviously fix the axes; but here, also, two independent measurements are necessary in order to enable us to calculate their length, as is explained later, p. 74. Hav- ing determined upon the relative lengths of the axes, one of these must be made the vertical axis (c), and then, of the two remaining, the shorter will be the brachydiagonal («), and the longer the macrodiagonal axis (J). In deciding these arbitrary points, the following serve as guides : The habit of the crystals ; the relations of the given species to those allied in composition; the cleavage, which is regarded as pointing to thitt form which is properly fundamental ; and other considerations. How arbitrary the choice generally is is well shown by the fact that, in a considerable number of species belonging to this system, different lengtlis of axes, as also dii! I'ont positions for them, have been adopted by different authors. ^Vhere an optical examination can be made of an orthorhombic crystal, the results show what the true position of the axes is, in accordance with the principles proposed by Schrauf, This subject is alluded to again in its proper place (p. 151). The general characteristics of the crystals of this SA'stem are not so marked as those of the preceding systems. The kind of symmetry should be well understood, though, as remarked on p. 50, ci-ystals which are in appearance orthorhombic maybe really raonoclinic; the true test of the system is to be found in the three rectangular axial directions. A pris- matic habit is very common, the prisms (except the diametral prism) not being square, also the prominence of some of the most c(»mnionly occur- ring macrodomes and brachydomes ; a prismatic cleavage is common, and often a cleavage exists parallel to one of the pinacoids {e.g.., i-'i) and not to the other, which could not be true in the tetragonal system ; similarly the planes ^-■^, i-l are sometimes physically different, e.g.., in regard to lustre. As has al)-eady been remarked, forms apparently hexagonal are common among certain species belonging to this system ; this is true in those cases * Siuce the above paragraph was put into type, Des Cloizeaux has announced that an optl* cal investigation by him has proved that huniite crystals, of types II. and III., are really TnonorU!tic. as suggested above. The figures are allowed to remain, however, siuce they illus trat« the form which this metlod of hemihedriem would produce. MONOCLIOTC SYSTEM. 47 where the prism has an angle approximating to 120^. It is immediately evident, as is explained more thoroughly in the chapter on componnd crystals, that if three individual crystals are united each by a prismatic face, when the prismatic angle is near 120°, they will form together a six-sided prism, approximating more or less closely to a regular hexa gonal piism. Similarly, under the same circumstances, the correspond iug pyramids will thus together form a more or less symmetrical hexagonal pyramid. This is illustrated by the accompanying ngures of witherite, wdiere the prismatic angle is 118°, 3u'. It need hardly be added that this is true in general, not only of the vertical prism, but also of a macrodome or brachydome, having an angle near 120°. The optical relations connected with this subject are alluded to elsewhere, p. 151. Planes of Symmetry. — The three diametral planes are planes of symmetry in this system, and they are the only ones. v.— MONOCLINIC SYSTEM. In the MoNOGLTNic SYSTEM the three axes are un- equal in length, and while two of them have rectan- gular intersections, the third is oblique. The position usually adopted for these axes is as shown in f. 214, wiiere the vertical axis, c, and lateral axis, 5, make retangular intersections, The same is true of h and d, while c and d are oblique to one another. The following is an enumeration of the several distinct forms possible in this system, deduced, as be- fore, from the general expression : 214 ,|3<90° —mc '. nh '. a [—7n-n' + ?nc : nb : a [ + m-n —rnc : h : 7ia [■—Tn-n +1710 : b : 7ia [ + ?n-7i —mc \h \ a [-771-] —c '.h'.a [-1] + mG :h : a [ + m] + c \h '. a [+1] mc : b : cca [m-tj j —mc : cob : a [— m-^] \ + mc : cob : a [ + m-^] \ CO c : Tib : a [i-7l[ \ oo c : b : na [i-)i x> c : b : a [/,] aoc : aob : a [i-i_ CO c I b : CO a [i-i Oc : b : a [0] The abridged symbols correspond to those in the orthorhombic system, explained on p. 49. The only point to be noted is that where n or i relates to the clinodi;igonal axis, n, this is indicated by nu accent placed over it, as ?/i-i, OT-/1 ; but in ?«-*', and ?}i-n, etc., ;' and ii refei to the orthudiagonal axis. Naumann wrote these mPcc , and mP.'i. or else with tha accent across the initial letter P. The minus signs are used in the same way as by Naumann (see p. 70). Pinacoiih. — -As in the orthorhombic system, there are three pairs of pinacoidal planes : the base 6^=0c \b \ a\ the oi^ihopinacoid, parallel to the 48 ORYSTALLOGKAPHT. 216 ortlio-axis (5) oo c : qo 5 : a, or i-i ; and the dinopi?iacoid, parallel to tlie in clined axis (d), oc g : h : oo a, or i-l. In the solid (f. 216) or diametral prism formed of these three pairs oi planeo, the four vertical edges are similar, and this is also true of tlie fonr edges between and i-l. On the otherliand, the four remaining edges are of two sets; that is, the edge in front above is similar to the edge be- hind and below, for the angles ai-e equal and inclosed by similar planes ; but these edges are not similar to the remaining two, since, though the planes are the same, the inclosed angles are unequal to the former. Further, there are two seta of solid angles, two in front and two dia- gonally opposite behind, being alike ob- tuse angles, and the other four alike and acnte. Prisms. — In consequence of the similarity of the vertical edges of the diametral prism, they must all be replaced if one is ; this is done by the unit prism I {oo c : b : a), in f. 215, 217. Of the other prisms, each obviously consist- ing of four planes, there are two series, the orthodiagonal, i-n, and clinodiagonal, i-h, beaiing the same relation to each otlier as the macro- and brachy-diagonal prisms in the orthorhombic system, in fact, the same explanation may be made use of here. Fig. 217, of a crystal of datolite from Toggiana, shows the pinacoid planes, as also the unit prism, /, and the clinodiagonal prism, i-^. Clinodomes. — The form m-i {mc : b : cc a) includes the four planes parallel to the clino- diagonal axis, and meeting the others at variable distances. They are analo- gous to the brachydomes of the orthorhoml)ic system. There ai-e four of these planes, because the two axes, c and b, make rectangular intersections. This is also seen in f. 218, since, as has been remarked, the four clino- diagonal edges in f. 215 are similar, and hence are simultaneously replaced by these clinodomes. 219 /v ,1 / / / \/ " v 220 Orthodomes. — Of the general form, mc '. (x> b : a, there are two sets oi planes, two in each {hemi-orthodomes), both of which are alike in that they are parallel to the orthodiagonal {b) axis (see f. 219). They are unlike, how- ever, in that two are opposite an obtuse angle, and two opposite the acute angle. Consequently these two pairs of planes are distinct, and must occur MONOCLINIO SYSTEM. 49 independently of each other. To distinguish between thera, those belonging to the obtuse sectants receive the minus sign (—m-^), and those belonging to the acute sectants the plus sign {+m-i), f. 219. This same point is illus- ti-ated by f. 220, where, as has been remarked, the obtuse edges, above in 221 222 223 front, and below behind, are similar, and are hence replaced by planes of the —m-i series, while the remaining two (f. 221), ai-e also similar, and are replaced by +m-i planes. Hemi-octahedroiis. — The same distinction of plus and minus belongs to all the pyramidal planes, and the signs are used in the same way. Foi each form there are only four similar planes. The m series is that of the unit octahedrons,— properly hemi-octahe drons, or hemi-pyramids +m and —m. The form made up of +1 and —1 is seen in f. 223, and in f . 222 the same planes are in combination with the three pinacoids. The general form, +')n-n, —m-n, and +ni-?i, —m-h, give each four simi- lar planes. They bear exactly the same relation to each other as the 7n-n and m-7i of the orthorhombic system, so that no additional explanation is needed here in regard to them. The figure (f. 217) of datolite may be referred to for illustrations of the diffeieut forms which have been named. There are here three different clinudomes -|-i, 24, and 4-i, each comprising four planes ; a minus hemi- orthodome (opposite the obtuse angle), —24, and also a plus orthodomc, + 2-i (these two planes are quite distinct, though numerically the symbols ;;re the same) ; moreover, of hemi-octaliedrons of the unit series, there are —4, — f, and +4, +2, +f, + l, + -|, +f ; also of orthodiagonal pyramids, —4-2, — Q-3, also +2-2, and of clinodiagonal planes, —8-^, and +12-f. A careful study of a few such figures, especially with the help of models, will give the student a clear idea of the synnnetry of this system. It will be noticed that all the planes above in front are repeated below behind, and those below in front appear again above behind. More important than this, it will be seen that the clinodiagonal diametral plane divides the crys- tal into two symmetrical halves, right and left; in other words, as remarked later, it is a plane of symmetry. Hemihedral forms occur of a hemimorjphiG character, iii whicli the planes about the opposite extremities of the vertical axis are unlike ; thus, the planes of one or more hemi-pyramids may occur at one extremity, without those corresponding at the otlier, as in tartaric acid, ammonium tartrate, etc. With many monoclinic crystals theobliquit\' is obvious at siglit ; but with many others it is slight, and can be determined only by exact measurements. 60 CRYSTALLOGRAPHY. In datolite it is only six minutes. The character of the symmetry exhibits further the obliquity. But, as seen above, both + and — planes of the same value do occur together, and though they are really distinct yet they may give a monoclinic crystal the aspect of an orthorhoinhic crystal. On the other hand, true orthorhombic crystals may be hemihedral, and thus may be monoclinic in the character of the symmetry (p. 45). Variable elements. — In the monoclinic system, the only element which is fixed is the position of the orthodiagonal axis {h) at right angles to the plane in which the other axes must lie. The lengths of these axes must obviously be assumed in the same way as in the preceding system; but, further than this, their position in the given plane, and the angle they make with each othei-, are both arbitrary ; in other words, any plane in the zone at right angles to the clinopinacoid may be taken as the base (6*) and any other as the orthopinacoid i^-i). The existence of a prismatic cleavage, or one paiallel to a plane in the orthodiagonal- zone often points to the planes which are leally to be considered fundamental. In many cases it is considered desirable to assume an angle near 90° as the angle of obliquity, so as to show the degree of divergence from the rectangular type. It need hardly be added that authorities differ widely both as to the position and lengths given to the axes of the same species. Plane of symifnetry. — Monoclinic crystals have but one plane of sym- metry, the diametral plane in which the vertical and clinodiagonal axes lie, that is, the plane parallel to the clinopinacoids. The maximum num- ber of similar planes for any form is four, and it will be noticed that there is no single form which alone can enclose a space, or form a geome *rical solid. YI.— TRICLINIC SYSTEM. In the Triclinic SYSTEM the three axes are unequal, and their intersections are mutually oblique. In consequeiice of this fact, there is no plane of symmetry. Only diagonally opposite octants are similar; there can conse- quently be only two planes of anyone kind. There are no truncations or bevclurents, and no interfacial angles of ^0°, 135°, or 120°. The prisms are all heinijprisms^ and the octahedrons tetarto-octahedrons. The lateral axes are called the maarodiagonal (b), and the brachydiago- nal {a). In f. 225 the diametral prism (made up of three pairs of different 228 planes) is represented, and in f . 224 the unit prism. To the latter is added (in f. 226) one plane -1 on two diagonally opposite edges, which are two out of the eight of the unit octahedron (f. 227). This octahedron, as will MATHEMATICAL CitrSTALLOGKAPHY. 51 I)e seen, is made up of four sets of different planes. The different kinds of planes are distino-uished l)v the long or short mark over the n (n or n) and also by giving those which oconr in the right-hand octants, in front, an accent; those above (in the obtnse octants) are niiuns, and the otheis phis. The form m-fi consequently may be —m-h\ or —m-n^ -{-m-n, oi + m-h\ and similarly with 7n-h. In f, 228 the unit prism is combined with a hemidome and a vertical plane parallel to the brachydiagonal section. The forms, although oblique in every direction, may still be closely similar to monoclinic forms of related species. 229 Anorthite. Axinite. The annexed figures are of triclinic species. In f. 229, of anorthite, of the feldspar group, the form is very similar to those of the monoclinic feldspar, orthoclase ; in orthoclase, O on the brachydiagonal (clinodiagonal) section is 90°, whence it is monoclinic, while in anorthite this angle is 85° 50', or 4° 10' from 90°, and this is the principal source of the diversity of angle and form. Fig. 230 represents one of the crystalline forms of axinite, nearly all of which fail of any special monoclinic habit. MATHEMATICAL CKYSTALLOGEAPHT. Introductory remarJcs on the proper syinbol of each plane of a general crystalline form. — Hitherto the symbol mc : 7ih : a has been employed to express the general position of all the planes comprising any crystalline form, and it has been shown that there are in some cases forty-eight similar planes answering to the general symbol, and in other cases only two. In order, however, to express the exact position of each individual plane be- longing to such a form, it becomes necessary to resort to the methods of analytical geometry. As shown in f. 231, the portions of the axes, when the centre is the starting point, which lie above, to the right, and in front of the centre, are called jjIus (+); the corresponding portions of the axes measured from the centre below, to the left, and behind, are called, for the 52 CK YSTALLOG R APR Y. sake of distinction, minim (— ). The planes of the first qnadrai.t (see also f. 232) are all p(j?itive (+); the planes of the second positive (+) with reference to the axes o and a, but negative (— ) witli reference to b ; in the 231 233 third, both lateral axes are negative (— ); in the fourth quadrant the planes are positive in regard to c and b, but negative with respect to a. The lower quadrants are respectively similar, except that the vertical axis is always negative. The symbols for each plane of the orthorhombic octahedron (f. 231), taken in the same order, will be as follows . Above, -+-C : -\-i : +a; +g : —h : +a; +c : —I : — «; +c : +h : —a. Below, —0 : +h'. +a; —c : —h : +a', —c : —h : —a: —g : +b : —a. The hexoctahedron (m« : na : a) may be taken as another example. The general symbol of the form of f. 247, p, 64, is 3-f {3a : fa : a), but the symbol of each plane is distinct. The same principle applies here as in the other case. Several of the planes in f. 247 are numbered to allow of convenient reference to them as examples, the appropriate symbols are written below; the order in the symbols is the same as that uniformly used in the work: 1st, the vertical axis (c) ; 2d, the lateral axis extending right and left (b) ; and 3d, the lateral axis, in front and behind (a). 1 = 3a : fa 2 = fa :3a 3 = a :3a 4 = a : §a :3a 5 = |a : a : 3a c b a 6 = 3a: a fa 7 = -3a : fa a 8 = -3a: a : fa 9 = fa: -3a: a = -3a : — fa : «, and so on It will be evident from these examples that to express the position of an individual plane the numbers expressing its relations to the three axes must all be regarded, each with its approi)riate sign ; in other words, the values of m, 7i, r, in the general form, mc : nb : ra, must all be given, one of them being unity; m always refers to the vertical axis, c'; n to the lateral axis, b\ r to the lateral axis, a ; as has already been remarked, a is usually made the unit axis. In the example last given the axes, leing all equal, are all called a. MATHEMATICAL CEYSTALLOGKAPHY. 53 Reference must be made here to the method of lettering the axes adopted in this work. The usag^e of the majority of authors is followed, and the subject is illustrated in the fol- lowing table. Common usage. ) This work ]• IsDmeti-.r:. Totrnfr. (F^xng.) O'-thorhombir, Trioliiiic. Mot.uclinic. vert. lat. vert, luacrodiag. bnichjdiag. vert, orttioiliag clinoding (Weiss, Rose. ) ) Miller's School, c cab Mohs, Naumann, a a a b c Dana (System 18G8) a a a c b It is certainly very desirable to indicate to which axis each letter refers by the mark placed above it ; in doing which, we follow Klein' a Einleitung in die KvystaUberechnung. s« DETERMINATION OF PLANES BY ZONES. Tlie subject of zones has been briefly explained on page 4, and varioua examples liave been pointed out. The principle is one of the highest im- portance, both practically, since it gives the means of determining the symbols of many planes witluMit calculation, and also theoretically. The laio of zo7ies, which states simply that the planes of a crystal lie in zones, is one of tlie most important of the science, and second only to that of the rationality of the indices. The planes of a crystal thus may be said to be connected together by these zones, a single plane often lying in a large number of zones. Parallelism in the combination edges, or mutual intersections of jdanes, is based upon some common geometrical i-atio, and this common ratio bp longs to the symbols of all the planes of the zone. 233 All planes which lie in the same zone will give exactly parallel reflections with the reflective goniometer, as explained on p. 87. This is the onlj' decisive test, and when possible should be made use of, since combination-edges often appear parallel when the planes forming them are not really in the same zone. Furthermore, inasmuch as parallel intersections are observed between planes of a zone only when they actually intersect, the goniometer may often serve to detect the ex- istence of zones not otherwise manifest. In f. 194, p. 43, the planes i-% i-H, I, t-5, ^-^, all lie in a vertical zone, and they are all obviously alike in this, that they are parallel to the vertical axis ; in other words, the common value c = oo be- longs to them all. Again, in the zone O, l-i, 24, Acanthite. ^-^, etc. (f. 197, p. 43), the planes are alike in that they are all parallel to the brachydiagonal axis ; in other words, <^ = cr- is true of all of them. Still again, the pyramidal planes i, 1, 2 (f. 150, p. 33), are also in a zone between O and /, and here the ratio 1 : 1 for the lateral axes applies to all ; also, 1-2, 2-2, 4-2, are in a zone from O to ?*-2, anc^ for them the lateral axes have the ratio 1 : 2. In the case of an oblique zone, as ^-^, 3-3, 2-5, 1, etc. (f. 233), this fact is less evident on inspection, but ig equally true, as will be seen later. The common ratio in this case is m = r. Since all the planes of a zone have a coranron ratio, which has been 54 CKTSTALLOGKAPHT. shown to be true in several examples but also admits of rigid proofj it is e^'ident that a plane whicli lies in two zones has its position deter- mined by that fact, since it must answer to two known conditions, in other words, the algebraic equation of a zone is known when tlie parame- ters of two of its planes are given, for they are sufficient to determine tJie common ratio, and by combining them the zone equation is obtained ; and further, when the equations of two zones are given, combiniug them will give the equation, that is, the parameters, of the plane common to both. The general equation, derived from Analytical Geometry, for any plane TYiG : nl) : r«, making parallel intei'sections wath the planes m'o : n'h : r'a and in"o : n"h : T"a is, M N li ^ , , . , — + -- i- — = : in which, Jf = in'rri"{n'r"-n"r'y, N= n'n" {r'm"-r"m')', R = r'r" {m'n"-m"n'). By substitnting the valnes of the parameters of two given planes for m', n\ r', and m", n", r" in the zone equation, a derived equation is obtained which expresses the relations between m, n, r of all the planes of the zone. The form of the general zone equation is so symmetrical that the calcnla- tions are in any case quickly and easily made i)y a method analogons to that used in Miller's system (as suggested by Prof. J. P. Cooke). If we write the parameters in parallel lines, repeating the first two teiuns, we have m' , n' \y r' \y m' \y n' m" , n" y\ 7'" /\ m" /\ n" and it will be seen that the coefficients M, JV, R are found by multiplying together the parameters in the manner which the scheme indicates. M= m'm" {n' r" — r'n"). iV= n'n" {r'Trh'—rn'r"). R = r'r" {tn'n" —n'm"). Take, for example, the zone of planes between i-l and 1 (f. 233). For iri, m' = i, n' = 1, r' = i ; for 1, m" = 1, n" = 1, r" = 1 {i = co); hence the scheme becomes 1 , 1 /\ 1 A 1 A 1 and for the several values of the coefficients M= i{l-i)= - t\ JV =1 {i-i) =0. R = i (^■ - 1) = i?. This reduces the zone equation torn = r (after dividing by ^^ = oo^), and to this all the planes of the zone conform. So also for the zone of l-l, /, 3-f, 14, etc., in f. 234. The parameters of the plane / and l-l arranged as above give i 1 1 i 1 1 i 1 1 i and the values of M, JV, R are —iJ^, —i^ and +i^ respectively. Hence the JBone equation becomes -i-i i =0 m n r ~ MATHEMATICAL CEYSTALLOGEAPIIY. 55 and if r = 1, the general formula n m is derived. Between ^ : 1 : 1 (/) in — l and 1 : / : 1 (I -I) tlie values of n, are p():?itive, as with the series of planes «: : 1-/ : 1-/' ; iSo:^h\a; 5 : | : 1 ; 4 : f : 1 ; 3 : | : 1 ; 2:2:1; | : 8 : 1, etc., 1:^:1. JJetween I'.i'.l 334 and -i the vahies of n aix; negative, that is, are measured on tho i)ack half of the axis h ; as, for example, f:-4:l;f:--3:l;|:-2:l;i: — ] : 1. As the zone continues on from ^ : —1 : 1 to 1 :- 1 : ±i (l-Oi 5^i>d i: -I: —1 (/),the nnit axis is changed, making u = — 1. The zone equa- — ■''^' tion then hecomes r = r, the values of r heino; positive between h : —1 : 1 and 1 : —1 : ± i, and negative between 1 : —1: ± i and i : —1 : —1. The successive planes are f : —1 : 2 ; f : —1:3; f:-l:4; 1 : -1 : ± ^ ; |:-l:-4; 3:_l:-3; 53 : -1 : -2, eti. Both figures 233 and 234 are illustrations of this zone. If the student will select a variety of examples of zones from the figures in the descriptive part of this work, and will apply the zone equation as given above to them, paying special attention to the signs of the parameters of each plane, he will soon find that the apparent difficulties of the subject disappear. EXHIBITION OP THE ZONE-RELATIONS OF DIFFERENT PLANES BY ME.\NS OF METHODS OP PROJECTION. 235 The relations of the different planes of a crystal are to some extent exhi- bited graphically in such ligures as have been already given. Other meth- ods, however, are nsed which have special advantages. The two most important are briefly mentioned here. 1. QueuHted^s method of ])r<>jection. — In this method the planes of a crystal are projected upon a horizontal plane, nsually that of the l)ase {0). Every jilane is regarded as pass- ing through the unit-length of the axis which is taken as the vertical ; these planes consequently appear as straight lines intersecting each other on the plane of projection. The following are examples. In f. 235, of galenite, there arc present the planes of the cube, octahedi'on, dodecahedron, and tetragonal trisoctaliedi-on ^-^. In the projection (f. 236) the plane of the paper is taken as that of the cubic plane, the two equal lateral axes (cj) are shown in the dotted lines, and the vertical axis is perpend icnlar to the plane of the paper at their point of intersection. Any arbitrary length of tlie lateral axes, as m, is taken as the unit. One of the cubic planes coin- cides with the plane of the paper, and the others, since they are su])|)0sed to pass through the unit point of the veitical axis, coincide with the projec- tions of the lateral axes, and are marked 11^ H. The octahedral planes (1) a[)pear as lines connecting the nnit lengths of the equal lateral axes ; of the dodecahedral planes, four pass each through 56 CRTS TALLOGRAPH Y. the exti-einity of one lateral axis, and parallel to the other, and four others are diagonal lines passing through the centre ; they are marked i in the figure. ' The o^her planes, f -f, when passing through the unit point of the vei'tic.al axis, ai-e represented hv the symbols 1 : f : 1, and 1:1 1 : I ; I, in the first quadrant, and similarly in the other three. I, and 236 / \ i 1 \ « , / / i y \ s $ ^ Q. & o / ^r\ />^ ■ /X^ /N. \ / \/ ^i^^ ^\ / \ / \ /^ i /^ H \ i ^^^ The projection of the first of these planes is the line joining the points a. (ex = f of ca')and a'' ; that of the second plane is the line joining the points a' and y (ey = ^ of car)', that of the third plane is the line joining the points s' and 3* (cs' = rz - f of ca). The same method is followed in the otlier quadrants, the twelve lines, lightly drawn, in the figure are the projections of the twelve corresponding planes of the form ^-f. Fig. 237. 238, give another example (topaz) from the orthorhomhic system. The dotted lines, as before (f. 238), show the latei-al axes on which the ]-olative unit lengths of b and d belonging to this species have been marked oft {b = 1.892, d = 1). The fonr lines passing through these unit points, a and b, are the pro- jections of the unit octahedron 1. The unit ]uism, /, is projected in lines parallel to these, and passing through the centi'e. The prism i-i also passes thi'ough the centre, but the direction is that of a line joining the unit length of the axis b with two times that of a. The symbol of the octahedron ^,[ = ^c : b : «), becomes, on supposing the plane to pass through the unit point of the vertical axis c : fi : ^a, and it is consequently projected in the lines MATHEMATICAL CKT8TALL0GEAPHT. 57 joining the points t (ct = % of ch), and s (cs = ^ of ca). The symbol of the plane f 2 (= f c : b : 2a) becomes, on the same condition, c : f 6 : ^a, and ita projection lines consequently connect the points t {ct =% of cb) and u {cit = ^oica). The same metliod is followed in the other systems; in the bexagonal there are on the plane of projection three equal lateral axes cuttini; each otlier at ano-les of 60°. It will be seen from these examples that planes in a zone all pasa throngli the same point of intersection; as in f. 234, O, f-f, 1, ^(«-), and, f. 237, /, i-i, i-i (c) ; this is also true mathematically of the planes (9, 1, #, /, whose projections are parallel. This principle, which follows immediatefy from the fact stated above that planes in a zone have a common ratio for two of the axes, is very important. If a given plane lie in two zones its projection must necessarily pass through tiie two points of intersections which belonor to each of these respectively, and consequently its position is determined. The plane on f. 237 which has no written symbol for instance, lying in the zone with | and f, and the zone with 1 and ^-5, must, when projected, pass through the intersecti(m point (f. 238) s of the former zone, and also through V that of the second zone. The plane itself, then, is one whi(^h meets the vertical axis at its unit length, the axis h obviously at an infinite distance, and the axis a at a distance f of its unit length ; henc^e, the sym- l;)ol is c : 00 5 : fa, or |c : oo J : a (|4) in the foj-ra it is usually Avritten, In many cases the ratios of the lateral axes ai-e o])vious at siuiit, as hcsrc ; in eveiw case, however, the position of the zonal point, and of tiie two jiointa of intersection on the axes, admits of exact determination by a series of 6im])le equations. These equations it is unnecessary to add here; reference fur them may be made to Quenstedt's Crystallography, or that of Klein, mentioned on p. 59. This method is of so general use and of so easy a])plication that every student should be familiar with it. Its advantages are that it leads to a clearer comprehension of the relations of the different forms, showing immtrdiately all the zones in which they lie, and in many cases — with:>nt the 58 CBYSTALLOGKAPHT. 239 use of equations — suffices to determine the symbols of an unknown plane, and that more simply than by the use of the zonal equation. The jreneral principles contained in the method have been made by its proposer (Quen- stedt) the basis of an ingenious and philosophical system of Crystal I ou-r.-ipny (Grundriss der bestiramenden und rechnenden Krystallographie von L''r. Aug. Queustedt, Tubingen, 1873). 2. Spherical 'projection of Neumann and Miller. — In this subject, as viewed by Miller, a crystal is situated within a sphere so that the centres of the two coincide. If now perpendiculars, or normals, be drawn from this centre to each pliine, and be produced, they will meet the surface of the sphere, and these normal points will determine the position of each plane. If, then, this sphere is regarded as projected upon a horizontal plane it will appear as a circle, and the various normal points will occupy each its pro- per position on or within this circle. Tliis will be made more clear by an example. If the crystal (f. 237) be supposed to occupy the centre of a sphere, and if the terminal plane coincide with the plane of the paper, a normal to the plane O will meet the sphei-e of projection at the central point (f. 239) ; the planes i-l at the points indicated, and so of the other planes 1 , f , *-2, etc, Two principles here aie of fundamental importance: 1st, all planes of a zo)ie have their nor- mals in the same great circle, as *-i, f, |-i, etc. ; and 2d, the an- gles between these normal points are the supplements of the an- fles between the actual jilanes. 'hese having been stated, it will be clear at once that the calcula- tion of the angles between dif- ferent planes, ^'.e., their normals, becomes merely a matter of solv- ing a series of spherical triangles in which some parts are given and others obtained by calcula- tion. Upon this basis a system of crystallography Avas construct- ed by Miller in 1839, which, as further developed by Grailich, Schrauf, von Lang and Maskelyno, has every advantage over tliat of Naiimann in the matter of facility of calculation as in some other even nioi-e impoit- ant respects. The method of construction of the circle of projection, for a given crystal, is in most casei Tery simple. The position of the crystal is commonly so taken that the prismatic zone is represented by the circumference of the circle, and the position of the normal-points of all prismatic planes lie upon it. The normal-points of the pinacoid planes are at 00'' from one another (the macropinacoid is not present on the crystal, f. 237). The two corresponding diameters, at right angles to each other, which are properly the projections of two great cir- cles, intersect at the centre the normal-point of the basal plane, ; these diameters repre- sent respectively the raacrodome {m-'i) and brachydome (/«-?") zones of planes. The several positions of the normal-points of the prismatic planes are determined by laying off the sup- plement anglea of each with a protractor ; that of i-t is 43° 25', and of /, 62" 8^', from the MATHEMATICAL CEYSTAILOG RAPHT. 59 normal-point of ^-^. The lines drawn between i-i, 0, and ^■-2 (behind), and Z, 0, /(behind) represent the zones of the ?ra-2 and m pyramids respectively. The position of the normal- points of a dome or pyramid upon its respective zonal line (great circle) is formed by laying off from the centre a distance equal to the tangent of half the supplement angle of the given plane on 0, taking the radius as unity. For example, A if-l =: 130° 27', hence the position of the required normal-point will be about i (.5040) of the radius measured from 0. It is in general necessary to determine in this way the normal-points of but very few oi the planes, since those of the others are given by the zonal connection between the planes. Thus in this case, having determined in the way explained the positions of the points i-i, i-i, I, and i-l, no further calculation is needed ; the point of intersection of the great circle joining i-i. 'j-i, and i-i, and that joining/, 0, /, is the normal- point of §; also the point of intersection of the great circle i-2, f-i, ^-2 with /, 0, /, is the normal-point of 1, and with «-2, 0, i-2 that of ^--2. The method explained is the same for all the orthometric systems ; for the clinometric sys- tems the same principle is made use of, though the application ia not quite so simple, since the basal plane does not fall at the centre of the circle. In the system of Miller the general form of the symbol is 7ikl, in which h, k, and I are alwaj's whole numbers, and, the reciprocals of Naumann's symbols. To translate the Jatter into the former it is only necessary to take the reciprocals and reduce the result to three whole numbers and write them in the proper order. In general, for m-n {mc : nb : a), h : k : I — mn : to : n, the latter expression being written in its simplest form, and, if neces- sary, fractional forms must be reduced to whole numbers by multiplication. Conversely, from 7ikl is obtained m = -, 7i = , and hence, -y — -- = m-n. This applies to all the sys- tems except the hexagonal, where a special process is required. See Appendix (p. 441). Methods of Calculation. In mathematical ci-jstallography there are three problems reqninnn;; solution : 1st, The determination of the elements of the crystallization of a species, that is, the lengths and mutual inclination of the axes; 2d, The determination of the mutual interfacial angles of like or unlike known planes ; and 3d, The determination of the symbols, that is, values of the parameters ni and n for unknown planes. This whole subject has been exhaustively discussed by Naumann in his several works on crystallography. (For titles, see p. iv.) The long series of formulas deduced bj'him covei almost every case which can arise. In the present place the matter is treated brielly, since for all ordinary problems in crystallography the amount of mathematics required ia very small. This is especially true in view of the fact that a large part of unknown planes can be determined by the zonal equation already given. When complicated problems do arise, the me "hods of spherical trigonometry (based on the spherical projection of Miller) offer, in the opinion of most crystallographers, the simplest and shortest mode of solution. It is be- lieved that the student who has mastered the elements of the subject, after the method of Naumann here followed, will, if he desire to go further, find it to his advantige to turn to the system of Miller, referred to on p. 58 (See also Appendix. ) The formulas given under the dilferent systems in the following pages are mostly those of Naumann, and it has been deemed desirable to explain at length, in most cases, the methods by which these formulas are deduced. If the student will follow these explanations through, he will find himself in a position to solve more difiScult problems invoking similar methods. Spherical triangles are employed in most cases, as early used by Hausmann (1818), by Naumann (1829), and others ; and carefully explained by Von Kobell in 1807 (Zur Berechnung der Krystallformen). The same methods have been elaborated by Klein (Einleitung in die Krystallberechnung, Stuttgart, 1875). THE B.\TIO OF THE TANGENTS IN RECTANGULAR ZONES. Tangent principle. — In any rectangular zone of planes, that is, a zont. Ijing between two planes at i-ight angles to each other, one of them being a diametral plane, the tangents of the supplement angles made with i\\vk 60 CET8TALLOGRAPHT. 240 diametral plane are proportional to the lengths of the axis corresponding to it. Examples of rectangular zones are afforded by the zones between i-i and i-i, also 1 and 0, f. 130, and / and (>, in f. 208 ; stili again between / and O, in f. 167; / and O, also ^■-2 and 6>, in f. 150. Iw^ 217, the zone be- tween i-i and i-\, and O and i-i^ as also the zones between i-i and any one of the orthodomes, are rectangular zones, but not the zones between the basal and vertical planes (except ^-^), nor those between i-i and a clinodome. The truth of the above law is evident from the accompanying figures. If the angles between the planes e^, (?, ; cos ^ = ^, - ■ ■ - . sm "IJ. ' » 2 tan (45° + 6) = m ; sin (45^ + ^) tan iA"= n. {c) Given B" and C". 1 ^„./T . ^ o COS 6V3 — COS iJ?" 2 cos iC'Vi = sm 6* ; cos S = . , „,,w/ » Bm ^B 'V2 tan (45°+ 8) = ri; sin (45° +i) tan ^B' ^m. The various combinations of liolohedral and hemihedral forms whicli mav occur are unlimited, and it would be unwise to attempt here to shoNV MATHEMATTCAL CRTSTAIXOGRAPHY. 67 the n~.etliods of \Torking them out. It is only necessary to remark that the solution can generally be readily obtained by the use of one or two spheri- cal triangles in the way siiown in the preceding cases. The calculation of the iuterfacial angles between two known forms caa often be performed by the formulas already given, or by similar methods For the more general cases, reference must be made to the cosine formula, p. 62. Inferfacial Angles. — I. HoloTiedral Forms. The following are some of the angles among the more common of [sometric holohedral forms; adjacent planes are to be understood, unless it is stated otherwise. The angles A^ B^ C\ above, are those over the edges so lettered in the figures referred to (see pp. 15-19), or over the corresponding edges in related forms : Hr\ H=90=,t 38 Ha 1 =125 16', f. 40, 41 Ha i =135, f. 43, 45. Ha «■-* = 146 19 Ha 1-2 = 153 26, £. 64 H A »-3 = 101 34 //aH = 133 19 //a^^ = 136 45 //a 2-2 = 144 44, f. 55 7/ A 3-3 = 154 46 //A*, ov. 1>=115 14 //A 2, " =109 28, f. 52 Ha 3, " =103 16 //a 3-1 = 143 18, f. 70 // A 4-2 = 150 48 //A 5-1 = 147 41 1 A 1 = 109 28, f. 42 1 Al. top, = 70 32 1 A !^' = 144 44, f. 47 1 A t4 = 143 11 1 A i-2 = 140 16, f. 67 1 A t-3 = 136 54 1 A M = 168 41 1 A 2-2 = 160° 33', f. 58 1 A 3-3 = 150 30, f. 57 1 A I = 109 49 1 A 164 12. f. 53 1 A 3 = 158 1 A 3-1 = 157 45 1 A 4-2 = 151 52 1 A 5-f = 151 25 A i = 120 f. 45 A i, ov. top,= 90 A i-'i = 167 42 A i-2 = 161 34, f. f A i-'S — 153 26 A 2-2 = 150 A 3-1 = 100 54 A 3-3 = 148 31 A 4-^ = 106 6 i A 5-f = 102 58i 2-2 A 2-2, i?,= 1.31 49, 2-2 A 2-2, C,= 140 27 2-2 A 2-2, ov. top. =109 28 3-3 A 3-3, i?,= 144 54, f. 61 3-3 A 3-3, (7,= 129 31 f. 54 t-J A i-'i A i-2 A i-2 A i-2 A i-2 A i-2 A i-3 A i-3 A 2 A 2 A 3 A 3 A 3-% 3-1 3-^, 4-2, 4-2 4-2, 54, 5-?., 5-i, i-i, .4,= 133" 49' J-*, 6',= 157 23 i-2, .4,= 143 8, f. 65 t-2, 6\=143 8 i-2, ov. top, = 126 53 1-3 = 171 52 2-2 = 155 54 i-3, A,= 154 9. f. 6fi 1-3, 6-,= 126 52 2, ^.= 152 44, f. 51 2, B, = 141 3i 3, A,= U2 8 3, ^,= 153 28i A,=z 158 13, f, 69 B,- 149 C, = 158 13 A,= 102 15 /?,^154 47i G, = 144 3 -4,= 152 20 B,= 160 32 C,= 152 20 II. Hemihedral Forms. The following are the angles for the corresponding hemihedral forms : 1 A 1 = 70° 33', f. 76, 76a \ A\, ^,= 162 39i \ A \, B,^ 82 10 3 A 2, ^.= 152 44, f. 85 3 A 2, 5,= 90 3 A3, ^,= 143 8 3 A3, ^,= 99 5 l-i AM, i?,= 93 23 I- J A ^^ C,= 160 15 2 3 A 2-2, ^,= 109 28, f . 81 23 ^ 2-2, 6',= 146 26^ 3 3 A 3-3, .5,= 124 7 In tlie forms ■i-f, «'-2 (f. 92), ^-S, ^-4, A is the angle at the linger edge, and C that at either of the others. 3-3 A 3-3, (7,= 134° 3' i-3 A i-3, C,= 107'37f 3-;^ A 3-^, ^,= 158 13, f. 87 4-3 A 4-2, ^,= 128 15 3-\ A 3-k B,= 110 55i 4-2 A 4-2, i?,= 154 47^ 3-^ A 3-^, 6',= 158 13 4-2 A 4-2, 6\=131 49 4-3 A 4-2, .4,= 163 15 3-1 A 3-% ^.= 115 23, f. IOC 4-2 A 4-2, ^,= 124 51 3-^ A 3-1, ^,= 149 4-2 A 4-2, 6',= 144 3 3-^ A3-a, C',= 141 47 i-h A »4, ^,= 112 37 5-|A5-t, yl,= 119 3i i-h A i-}, C,= 117 29 5-^ A5-f, i?,= 160 33 i-2 A i-2. /I, = 126 52,193, 93 5-§a5-^, 6',= 131 5 i-2 A i-2. 6',= 113 35 i-3 A «-3, ^,= 143 8 68 OKTSTALLOGKAPHT. II. — Tetkagonal System. In the Tetragonal system, as lias been fully explained (p. 30), the lonffth oi the vertical axis is variable, and must be determined for each species. If the length of c is known, then it may be required to determine the symbols of certain planes by means of measured angles. These two problems are in a nieasure complementary to each other, and the same methods will give a snhition to either case. (For figures of the forms see pages 27 and 28.) The calculation of the interfacial angles can be pericyrmed by similar methods or by the cosine formula. 1. Form m. — The edges are of two kinds, pyramidal X^ and basal Z. If either angle is known, the angle a, which is the inclination of the edge X on the lateral axis, may be calculated by the spherical triangle, as in ■f. 24:2, 243. (Compare the explanation of this case, p. 62.) Obviously in the plane right-angled triangle formed by the two axes and the edge X^ tan a = iiic (since a = 1). If c is known, then m is determined ; and, con- versely, a value being assumed for w, in the special case, c is given by the calculation. The general formulas are : cot \X= sin a, or tan ^Z V i = tan a ; then tan a — mc. 2. Form m-i. — {a) Given the angle Z, mc is found innnediately ; the solution is obvious, for in the section indicated l»y 249 the dotted line (f. 249), ^Z = a, and the tangent of this angle is equal to the vertical axis, (b) Given the angle Y. A spherical triangle placed as in f. 249, has one angle = -2 j^^, a second = 45°, and the third = 90°, whence the side opjXisite i V is calculated, which is the complement of a. The general formulas, which may serve to de- duce the value of m, when c is given, or the con- verse, are : cos ^ Y V^ = sin a, or tan ^Z = tan a, and tan a = mc. If a series of square octahedrons 7n, or m-i, occur in a vertical zone, their symbols may be calculated in both cases alike by the law of the tangents, tiie angles of the planes on O, or on /, or i-i, respectively, being given. (See p.^60.) 3. Form i-?i. — For the angle of the edge X(f. 109, p. 26), at the extrem- ity of a lateral axis, tan ^X = 7i. From the angle of the other edge Y, we have iA" = 135°- ^Y; and hence, tan (135°- ^Y) = n. 4. Form m-n. — The edges are of three kinds, X, Y, Z(f. 250), and two angles must be given in the general case to determine ?/i and 7i. (a) Given Xand Z. A spherical triangle having its vertices on the edges Xand Z, and the lateral axis, as 1, f. 250, will have two of its angles equal to iX, -^Z, respectively, and the third equal to 90°. The solution of this triangle gives the sides, viz., a and v, the inclinations of the edges X and MATHEMATICAL CET8TALL0GRAFHY. H9 Z, respectively, on the lateral axis. The tangents of these angles give the values of in and n. The formulas are as follows : cos \Z = cos a, tan a = tnc ; sin kX cos \X sin \Z = cos V, tan v z= n. 250 (J) Given Y and Z. In a second triangle placed as indicated (2, f. 250), two of the angles are |- J^and ^Z respectively, luid the third is 90°. The solution of this second triangle gives 8, the inclination of the edge Z on the diagonal axis, from which, in the plane Triangle we have v = 135® — B, and from v is ob- tained n. Still again from the triangle 1 (f. 250), and its solution used in the preceding case, having given Z and v, a is obtained, and from it ?n, as by the following formulas : cos ^ sin ^Z 1^ = cos 8,v = 135^-8, i&nv = n ;' 2Z tan ^Z sin v = ta,n a = ma {(i) Given X and Y. A third triangle, numbered 3 in the fignre, has two of the angles equal to^-Xand ^Irrespectively, and the third is 45°. Solv- iaig this oblique-angled triangle, the angle of the inclination of the edge Y en the vertical axis is obtained, and its complement is the angle e, the in- clination of the edge J^on the diagonal axis; from e and i F are obtained, by triangle 2, S, and thence, as above, n; and finally, from JT and v, k obtained a, and from that the value of in. The simplified formulas are as follows : cos*Fi/2 — " 1 V — = n—1 ; sin a = n cot hX, tan a = mc. cos -kA ' " ' Pyramids of the general symbol l-7i, m-w, etc., are especial cases of the preceding, the processes being for them, however, somewhat simplified. A single measurement is sufiicient. III. Hexagonal System. In the Hexagonal system there are three equal lateral axes {a) inter eecting at angles of 60°, and a fourth vertical axis (c) at right angles to the plane of the others. Taking a = 1, tliere remains but one unknown quantity in the elements of a crystal, that is the length of c, and a Bingle measurement is sufiicient to determine this. The relations of the three lateral axes have been explained on p. 32. The hexagonal system is closely allied to the tetragonal, and optically they are identical, as is shown beyond. Schi-anf refers all hexagonal forms to two lateral axes crossing :b: na {i-n), h being the unit axis. Thus *-J {coG : ^h : a) becomes *-2 (00 c? : J : 2(2). 2. Domes, 771-I and m-i. — No further explanation is needed (f . 255) ; here tan /3 = mc, or b tan 7 =: mc. 3. Octahedrons, m. — Here the angle a is always known (it being the same as for the unit-octahedron where tana = 3), and hence a single meas- ured angle, X, Y, or Z will give the values of either jB or 7 for the given form, and tan ^ = mc, h tan 7 = mc. 4. Forms m-h or m-n. — The measurement of the angles X, Y, Z Avill give the values of a, /3, and 7 belonging to the given form, and tan yS = ?/zc, tan a = nb, etc. Here, as in the prisms, if n is less than unity, when the axis & is the unit, the symbol is transposed, and the axis b made the imit, thus '2ic: ^b '. a (2- jj becomes 4c : J : 2a (4-2). If the angle between the form 7n-n (or 'm-n) and either of the pinacoide can be measured, the method of calculation is essentially the same (Com- pare f. 24S) ; for m-n A O (base) = supplement of the angle |-Z; m,-n A i-l (macropinacoid) = supplement of the angle ^Y \ and 7)i-n A i-i (brachypinacoid) = supplement of the angle -^X, The method of calculation of planes in a rectangular zone by means of the tangents of their supplement basal angles finds a wide application in this system. It applies not only to the main zones to i-i (macrodomes), <*' CRYSTALLOGRArHY. O to i-l (brachydomes), i-% to ^-^ (vertical prisms), and I to (unit oclahe« (Irons), but also to an}' z.me of octahedrons m-/l (or m-n) between O and i h (or i-h)j and any transverse zone from i-i to ra-l, and i-l io m-l. V. MoNOCLiNic System. In the Monoclinic system the number of unknown quantities is three, viz., the lengths of the axes c and b, expressed in terms of the unit clinodiagonal axis d, and the oblique angle /3 (also called C), between the basal and vertical diametral sections, that is, between the axes c and d. Three independent measurements are needed to determine these crj^stallographic elements. The angle /3 is obtuse in the upper front quadrants, and acute in the lower front quadrants; the planes in the first mentioned quadrants are distinguished from those be- low by the minus sign. The unit octahe- dron is made up of two hemi-octahedrons (—1 and +1), as shown in f. 256. Calculation of the Lengths of the Axes^ and the A7igles of obliquity. Represent (see f. 256) the inclination of the Edge X on the axis c by /i. X o\^ d by v. Y on c by p. X " " c " ill. X on d by v. Z on d by o-. For the relation of the axes in terms of these angles we have : (1) In the oblique-angled plane triangle, in the clinodiagonal section sin V , ^ <2 : c = sm ii : sin v. or, c = -: — when a ■=■ 1. ' sm/i tan It, = a sin /3 c — a cos /3* , a sin yS tan u, = — 5. '^ c-\-a cos p tan V _ c sin /3 a — c cos yS* /, 2 sin II sin u! tan^ = ■ f 9. sm [fi — fj, ) /i -f ^ + yS = 180° tan v' = tan /8 = c sin /3 a + c cos y3 2 sin V sin v' sin {v — v') ' fi' + v'= 13. Furtlier, (2) In the right-angled triangle of the orthodiagonal section, J cot p = A MATHEMATICAL CRTSTALLOGKAPHT. 77 (3) In the basal section, d tan A - 1-i = 180°- v'; O /\ + 1-i = 180° — V. By the formula ffiven above, tan 8 = — — -, 7—, also, u = 180' •^ ^ ' Bin {v — v') ^ ' ^ — {0 + v). Thus /3, /i, and v are known, and from them the relation of the axes d and c is deduced. (c) Given i-i, - 1-i and + 1-i. i-i A - 1-i = 180°- fi',i-iA + 1-i = 180' -fi. As before, tan ^ = ^ ^^" /" «^" f^' and v = 180°- (/3 + /*). 78 CRT8TALL0GRAPHT. 257 {d) Given the prism I and O (f. 257). In the spherical triangle ABG^ C — 90° (inclination of base on cliiiodi agonal section), B =0 nI^ -4 = \{ T N I). Hence, the sides CA and CB are calculated ; CA = /3 (or, aa in this case, 180°— ^) ; CB = cr, which gives the ratio of the lateral axes, d and b. (e) Given t-/, 1-i and O. 0/\i-i (behind) = y^, and sin (d tan [(OAl-i) - 90°] = tan p. {/) Given + 1 and — 1, form as in f. 256. The angles between the planes + 1 and — 1 and the diame- tral sections are indicated by the letters JT, Y, etc., aa before explained (p. 77). The relations between these angles and the angles fi, v, p, etc., are given in the fol- lowing formulas, deduced by means of spherical triangles: cos Y cos /X = 7r, sm Jl cos fl cos Y ' sin X" cos X cos X' cos p = -. — ^ = —. ==, . '^ sm Y sm Y cos V also, cos Z sin , cos Z' cos V = —. — ^, sm X cos (T = cos X _ cos JT^ sin Z sm tan -c^ tan tr tan p , t^-, tan o- X— -; = -1 — - , tan Jl = , sm 1/ sm fl tan o- tan p sin I/' sin /*' . .^ tan it .^ tan it' _ tan y „, tan i/ tan F= -^— ^ tan Y= -t-^ , tan Z = -. — , tan Z = -r . sm p sm p sm a sm Calculation of the values of m and n. In general, it may be said that the methods of calculation are the same ds those already given. In each case the values of p,, v, p, and a. Also, let A = angle of inclination of the diame- tral planes meeting in the axis d ; J^ = arigle of inclination for those intersecting in the axis b, and C = the angle of those meeting in c. The macrodiagonal (m-n) and brachy diagonal (jn-n) planes are indicated as in the orthoi-hombic system, also the planes opposite the acute angle (yS) are called +, and those opposite the coi-re- sponding obtuse angle — ; furthermore, the planes in front, to the right (and behind, to the left) are distinguished by an accent, as vb-n'. In the fundamental octahedron formed by four sets of planes, these arC; taken in the usual order (f. 227), — 1', — 1, +1', + 1, and below, + 1', + 1,-1',-!.^^ In the determination of any individual crystal belonging to this system, the axial directions as well as unit values have to be assumed arbitrarily ; in many cases {e.g., axinite) the custom of diffei-ent authors has varied much. Two points are to be considered in making the choice: 1, the cor- respondence in form witii related species, even if these be not triclinic, as, for example, in the feldspar family ; and 2, tlie ease of calculation, which is much facilitated if, of the planes chosen as fundamental, the pinacoids are all, or at least in part, present. In genei'al, the methods of calculation are not simple. Some of the most important relations are given here (from Naumann). In actual practice, problems which ai'ise may be solved by some of the following formulas, or by means of a series of appropriate spherical triangles, used as in the preceding pages, and by which, from the measured angles, the required elements of the forms may be obtained. In addition to the angles already defined, let, as follows (f. 259), X ~ inclination of a plane on the brachydiagonal section ; Y= " " " macrodiagonal " Z= " « " basal " Let the inclination of the edg-e, X^ on c = /A, Y on c = p, Z ond := ~> sm ^ sin ^ ' also, sin a : sin /3 : sin 7 = sin A : sin B : sin 6'. The relations between the angles a, yS, 7, and the angles /^, v, etc., are as follows : 2 sin p sin p 2 sin tt sin ir' tan a = —. — f- /^ = -; — -. ^. sm [p — p) sin (tt — TT ) _ 2 sin /A sin a' 2 sin y sin v' tan yS = . ."^ ^ = —. — 7 j^. sin (/i — /jb) sin (j/ — 1/ ) 2 sin T sin r' 2 sin a sin <' nf^ J i^'^ffe- ^ i ">7^ peai-s, however, to be an eight-sided prism, bounded laterally by the planes 7?, l^ 1^ and i?, and their opposites, and terminated by the remaining planes. The following figures of quartz (f. 354:, 355) represent distorted forms of this mineral, in which some of the pyramidal faces by enlargement dis- place the prismatic faces, and nearly obliterate some of the other pyramidal faces ; see also f. 336. 353 354 355 Calcite. Quartz. Quartz Fig. 356 is a distorted crj'stal of apatite ; the same is shown in f. 357 with the normal symmetry. The planes between O and the right 1 are enlarged, while the corresponding planes below are in Dart obliterated IBBEGULAJirnES OP CBTSTAL8. 107 By observing that similar planes are lettered alike, the correspondence ci the two figures will be understood. In deciphering the distorted crystalline forms it must be remembered that while the appearance of the crystals may be entirely altered, the angles remain the same ; moreover, like planes are physically alike, that is, alike in degree of lustre, in striations, and so on. 856 357 Apatite. Apatite. In addition to the variations in form which have just been described, still greater irregularities are due to the fact that, in almost all eases, crystals in nature are attached either to other crj'stals or to some rock surface, and in consequence of this are only partially developed. Thus quartz crystals are generally attached by an extremity of the prism, and hence have only one set of pyramidal planes ; perfectly formed crystals, as those from Herkimer Co., N. Y., having the double pyramid complete, are rare. The same statement may be made for nearly all species. III. Variations in the Angles of Crystals. The greater part of the distortions described occasion no change in the interfacial angles of crystals. Bat those imperfections that produce con- vex, curved, or striated faces, necessarih'' cause such variations. Further- more, circumstances of heat or pressure under which the ciystals were formed may sometimes cause not only distortion in form, but also some variation in angle. The presence of impurities at the time of crystallization may also have a like effect. Still more important is the change in the angles of completed crystals which is caused by suljsequent pressure on the matrix in which they were formed, as, for example, the change which may take place during the more or less complete metamorphism of the enclosing rock. The change of composition i-esulting in pseudomorphous crystals (see p. 113) is generally accompanied by an irregular change of angle, so that the pseudomorphs of a species vary much in angle. In general it is safe to affirm that, with the exception of the irregularitiefi 108 CEYSTALLOGRAPHT. arising from imperfections in the process of crystallization, or from changes produced subsequently, variations in the angles are rare, and the constancy of angle alluded to on p. 87 is the univei-sal law.* In cases where a greater or less variation in anoxic has been observed iu tlie crystals of the same species fi-om different localities, the cause for this can usually be found in a difference of. chemical composition. In the case of isomorphous compounds it is well known that an exchange of correspond- ing chemically equivalent elements may take place without a change of form, though usually accompanied with a slight variation in the funda- mental angles. The effect of heat upon the form of crystals is alluded to upon p. 168. lY. Internal Imperfections and Impurities. The ti'ansparency of crystals is often destroyed by disturb^ crj'stalliza- tion, or by impurities taken up from the solution during the process of crystallization. These impurities may be simply coloring ingredients, or they may be inclosed particles, fluid or solid, visible to the eye or under the microscope. The coloring ingredients may vary in the course of formation of the crystals, and thus layers of different colors result ; the tourmaline crystals of Chesterfield, Mass., have a led centre and blue exterior ; others from Elba are sometimes light-green below and black at the extremity ; many other examples might be given. The subject of the tluid and solid inclosures in crystals is one to which much attention has been directed of late years. Attention was early called to its impcM-tance by Brewster, who described the presence of fluids in quartz, topaz, beryl, chrysolite, and other minerals. In later years the mat- ter has been more thoroughly studied by Sorby, Zirkel, Vogelsang, Fis(;her, Rosenbusch, and many others. (See Literature, p. 111.) Many crystals contain empty cavities ; in others the cavities are filled sometimes with water, or with the salt solution in which the crystal was formed, and not infrequently, especially in the case of quartz, with liquid carbonic acid, as first proved b}' Vogelsang, and recently followed out by Hartley. These liquid inclosures are marked as such, in many cases, by the presence in the cavity of a movable bubble. The solid inclosures are almost infinite in their variety. Sometimes they are large and distinct, and can be referred to known mineral species, as the scales of hematite to which the peculiar character of aventurine felds))ar is due. Magnetite is a very common impurity for many minerals, appearing, for example, in the Pennsbury mica; quartz is also often mechanically mixed, as in staurolite and gmelinite. On the other hand, quai tz crystals vei-y commonly inclose foreign material, such as chlorite, tourmaline, rutile, hematite, asbestos, and many other minerals. * Reference must be made here to the discussion by Scacchi of the principle of " Polysym- metry." (Atti Accad. Napoli, i., 1864.) See'also Ilirschwald, Zur Kritik des Leucitsystemfl, Tech. Mill. HFitth., 1875, 227. See further the discussiou ou pp. 185 et seq. IKBEQULAKITIES OF CKTSTAL8. 109 The inclosures may also consist of a heterogeneous mass of material ; as the gi-anitic matter seen in orthoclase crystals in a porphyritic granite ] or the feldspar, quartz, etc., sometimes inclosed in large coarse crystals of beryl, occurring in granite veins. An interesting example of the inclosure of one mineral b}' another is afforded by the annexed figures of tourmaline, enveloping orthoclase (E. H. A^illiams, Am. J. Sci., III., xi., 273, 1876). Fig. 358 shows the crystal of tourmaline ; and cross-sec- tions of it at the points indicated {a, b, g) are given by f. 359, 360, 361. The latter show that the feld- spar increases in amount in the lower part of the crystal, the tourmaline being merely a thin shell. Similar specimens froui the same locality (Port Henry, Essex Co., N. Y.) show that there is no ne- cessary connection between the position of the tour- maline and that of the feldspar. Similar occurrences are those of trapezohedrons of garnet, where the latter is a mere shell, enclosing calcite, or sometimes epidote. Analogous cases have been explained by some authors as being due to partial pseudomorpb ism, the alteration progressing from the centre outward. 360 The microscopic crystals observed as inclosures may sometimes be referred to known species, but more generally their true nature is doubtful. The term microlitesy proposed by Vogelsang, is often used to designate the minute inclosed crystals ; they are generally of needle-like form, some times quite irregular, and often very remarkable in their arrangement and gi-oupings ; some of them are exhibited in f. 367 and f. 368, as explained llu CET8TALL0GRAFHT. below. Trichite and belonite are names introduced by Zirkel ; the former name is derived from 6pi^, hair, the forms, like that in f. 362, are common ill obsidian. Where the minute individuals belong to known species they are called, for example, feldspar microlites, etc. Crystallites is an analogous term which is intended by Vogelsang to cover fhose minute forms which have not the regular exterior form ot crystals, but may be considered as intermediate between amorphous matter and true crystals. Some of the forms, figured by Vogelsang, are shown in f. 363 to 366 ; tliey are often observed in glassy volcanic rocks, and also in furnace elags. A series of names have been given to varieties of crystallites, such as globulites, margarites, etc.* The microscopic inclosures may also be of an irregular glassy nature ; a kind that exists in crystals which have formed from a melted mass, as lavas or the slag of iron furnaces. In general, it may be said that while the solid inclosures occur sometimes quite irregularly in the crystals, they are more generally arranged with some evident reference to the symmetry of the form, or planes of the crystals. Examples of this are shown in the following figures : f. 367 ex .S()7 Augite. Leucite. Calcite. hibits a crystal of augite, inclosing magnetite, feldspar and nephelite microlites, etc.. and f. 368 shows a crystal of leucite, a species whose crystals very com.monly inclose foreign matter. Fig. 369 shows a sectioji of a crystal of calcite, containing pyrite. Andalusite. Another striking example is afforded by andalusite, in which the ineloaea impurities are of considerable extent and remarkably arranged. Fig. 370 bIiows the successive parts of a single crystal, as dissected by B. Ilorsford * Die Krystalliten von Hermann Vogeleang. Bonn, 1875. CRYSTALLINE AGGKEGATES. Ill of Springfield, Mass.; 371, one of tie four white portions; and 372, the central black portion. 371 873 Literature. Some of the most important works on the subject are referred to here, but for a compI«t« Ust of the literature up to 1873, reference may be made to Rosenbusch (see below). Blum, Leonhard, Seyfert, and Sochtinff, die Einschliisse von Mineralien in krystallisirten Mineralien. (Preisschrif t. ) Haarlem, 1854. Breicger. Many papers published mostly in the Philosophical Magazine, and the Edinburgh Phil. Journal, from 1822-1856. ^ Fischer. Kritische-microscopische mineralogische Studien. Freiburg in Br 64 pp 1869 • Ite Fortsetzunff, 64 pp., 1871 ; 2te Forts., 96 pp., 1873. "' ' Kosmann. Ueber das Schillem und den Dichroismus des Hypersthens Jahrb Min 1869 368 (ibid. p. 532, 1871, p. 501). ' '' ' Ronenhnsch. Microscopische Physiographie der petrographisch wichtigen Mineralien 395 pp., Leipzig, 1873 Schrauf. Studien an der Mineralspecies Labradorit. Ber. Ak. Wien, Ix., Dec, 1869. Sorby. On the microscopical structure of crystals, indicating the origin of minerals and rocks. Q. J. Geol. Soc, xiv. , 453, 1858, (and many other papers). 8orby and Butler. On the structure of rubies, sapphires, diamonds and some other minerals Proc. Roy. Soc, No. 109, 1869. Vogehang. Die KrystaUiten. 175 pp., Bonn, 1875. Vogelsang and Oeissler. Ueber die Natur der Flussigkeitseinschliisse in gewissen Miaera- lien. Pogg. Ann., cxxxvii., 56, 1869 (ibid. p. 257). Zirkcl. Die microscopische Beschaffenheit der Mineralien und Gesteine. 502 dd Leinziir 1873. ^^'' ^ "' CRYSTALLINE AGGREGATES. The greater part of the specimens or masses of minerals that occur, may be described as aggregations of imperfect crystals. Even those whose structure appears tlie most purely impalpable, and the most destitute in- ternally of anything like crystallization, are probably composed of •crystal- line grains. Under the above head, consequently, are included all the remaining varieties of structure in the mineral kingdom. The individuals composing imperfectly crystallized individuals, may be: 1. Coluimxs^ or fibres^ in which case the structure is coluTYinar. 2. Thill layninoD, producing a lamellar structure. 3. Grains, constituting a granular structure. 1. Columnar Structure, A mineral possesses a c()lumnar structure when it iS made np of slender iKilumns or hbres. There are the following varieties of the columnar struo ture : Fibrous : when the columns or fibres are parallel. Ex. gypsum, asbeatua Fibrous minei-als have often a silky lustre. 112 CETSTALLOGRAPHT. Reticxdated : when the fibres or cohimns cross in various directions, and produce an appearance liaving some resemblance to a net. Stellated or stellular : when tliey radiate from a centre in all directiors, and produce star-like forms. Ex. stilbite, wavellite. Hadiated, divergent : when the crystals radiate from a centre, without producing stellar forms. Ex. quartz, stibnite. 2. Lamellar Structure. The structure of a mineral is lamellar when it consists of plates or leaves. The laminae may be curved or straight, and thus give rise to the curved lamellar, and straight lamellar structure. Ex. wollastonite (tabular spar), some varieties of gypsum, talc, etc. When the laminae ai-e thin and easily separable, the structure is said to be foliaceous. Mica is a stfiking example, and the term micaceous is often used to describe this kind of structure. 3. Granular Structure. The particles in a granular structure differ much in size. When coarse, the mineral is described as coarsely gra,mdar j when fine, ^*;i(??y granular , and if not distinguishable by the naked eye, the structure is termed im- pal^Kihle. Examples of the first may be observed in granular crystalline limestone, sometimes called saccharoidal ; of the second, in some varieties of hematite ; of the last, in chalcedony, opal, and other species. The above terms are indefinite, but from necessity, as there is every degree of fineness of structure in the mineral species, from perfectly im- palpable, through all possible shades, to the coarsest granular. The term phanero-crystalline has been used for varieties in which the grains are dis- tinct, and c7'i/pto -crystalline^ for those in which they are not discernible. Granular minerals, when easily crumbled in the fingers, are said to be friable. 4. Imitative Shapes. Reniform : kidney shape. The structure may be radiating or concentric. Botryoidal : consisting of a group of rounded prominences. The name is derived from the Greek ^orpv n. 1 73. 124 PHYSICAL CHARACTERS OF MINERALS. order to obtain uniform results: 60° F. is the most convenient, and has l.eeii generally adopted. But the temperature of the maximum density of water, 39.2° F. (4° C), has been recommended as preferable. For minerals soluble in water some other liquid, as alcohol, benzene, etc., nmst be em- ployed whose specific gravity {g) is accurately known ; from the coin- prison with it, the specific gravity {G) of the mineral as referred to water IS determined, as by the formula : G w w — w A very convenient form of balance is the spiral balance of Jolly, where the weight is mea- sured by the torsion of a spiral brass wire. The readings, which give the weight of the min- eral in and out of water, are obtained by observing the coincidence of the index with its image reflected iu the mirror on which the graduation is made. A form of balance in which weights are also dispensed with, the specific gravity being read off from a scale without calculation, has recently been described by Parish (Am. J. Sci., III., X., 352). Where great accuracy is not required, it can be very conveniently used. 373 If the mineral is not solid, but pulverulent or j)orous, it is best to reduce it to a ])Owder ard weigh it in a little glass bottle (f. 373) called a pygnometer. This bottle has a stopper which fits tightly and ends in a tube with a very fine opening. The bottle is filled with distilled water, the stoi)per in- serted, and the overflowing water carefully removed with a soft cloth. It is now weighed, and also the mineral whose density is to be determined. The sto})per is then removed and the mineral in powder or in small fragments inserted, with care, so as not to introduce air-bubbles. The water which overflows on i-eplacing the stopper is the amount of water displaced by the mineral. The Aveight of the pygnometer with the enclosed mineral is determined, and the weight of the water lost is obviously the difference l)etweeii this last weight and that of the bottle and mineral together, as first determined. The specific gravity of the mineral is equal to its weight alone divided by the weight of the equal Volume of water thus determined. Where this method is followed with sufticient care, especially avoiding any change of temperature in the water, the results are quite accurate. Other methods of determining the specific gravity will be found described in the literature notices which follow. It has been shown by Rose that chemical precipitates have uniformly a higher density than belongs to the same substance in a less finely divided state. This increase of density also characterizes, though to a less extent, a mineral in a fine state of mechanical subdivision. This is explained by the condensation of the water on the surface of the powder. It may also be mentioned that the density of many substances is altered by fusion. The same mineral in different states of molecular aggregation may differ somewhat in density. Furthermore, minerals having the same chemical composition have sometimes different densiries ( orresponding o> the different crystalline forms in which they appear (see p. 199). LIGHT. 125 For all minerals in a state of average purity the specific grp,vi-.y is one of the most important and constant characteristics, as urged especially by Bi-eithaupt. Every chemical analysis of a mineral should be accompanied by a careful determination of its density. Practical suggestions. — The fragment taken should not be too large, say from two to five grams for ordinary cases, varying somewhat with the density of the mineral. The substance must be free from impurities, internal and external, and not porous. Care must be taken to exclude air-bubbles, and it will often be found well to moisten the surface of the specimen before inserting it in the water, and sometimes boiling is necessary to free it from air. If it absorbs water this latter process must be allowed to go on till the substance is fuUy satu- rated. No accurate determinations can be made unless the changes of temperature are rigorously excluded and the actual temperature noted. In a mechanical mixture of two constituents in known proportions, when the specific gravity of the whole and of one are known, that of the other can be readily obtained. This method is often important in the study of rocks. Literature. — Specific Gravity. Beudant. Pogg. Ann., xiv., 474. 1828. Jemsch. Ueber die Bestimmung der specifischen Gewichte ; Pogg. xcix., 151. 1856. Jollil. Ber. Ak, Mimchen. 1864, 162. Gadoliii. Eine einfache Methode zur Bestimmxing des specifischen Gewichtes der Minera- lien; Fogg., cvi., 2ia. 1859. Q. Hose. Ueber die Fehler, welche in der Bestimmung des specifischen Gewichtes dei Korper eutstehen, wenn man dieselben im Zustande der feinsten Vertheilung wiigt ; Pogg. Ixxiii.. Ixxv . 40ii. 1848. t^clicerer Ueber die Bestimmung des specifischen Gewichtes von Mineralien ; Pogg. Ann., Ixvii.. 120, 1846. Journ. pr. Ch., xxiv., 139. bchiff. Ann. Ch. Pharm., cviii.. 29. 1858. Schroder. Neue Beitrage zur Volumentheorie ; Pogg. cvi. , 226. 1859. ; Die Volumcoustitution einiger Mineralien ; Jahrb. Min , 1873, 561, 932 ; 1874, 399 etc. Tschcrmak. Ber. Ak. Wien. 292, 1863. Wibukff. Die Slineralien nach den fiir das specifische Gewicht derselben angenommenen and gefundenen Werthen ; 170 pp. Breslau, 1868. III. LIGHT.* Befoi-e considering the distinguishing optical properties of crystals of the different systems, it is desirable to review briefly some of the more im- portant principles of optics upon which the phenomena in question de])end. jYature of light. — In accordance with the undulatory theory of Huy- Ljhens, as further developed by Young and Fresnel, light is conceived to consist in the vibi'ations, transverse to the direction of propagation, of the {•articles of imponderable, elastic ether, which it is assumed pervades all space as well as all material bvKlies. These vibrations are propagated with great velocity in straight liiu^s and in all directions from the luminous point, and the sensation which they produce on the nerves of the eye is called light. The nature of the vibrations will be understood from f. 374. If AB re{)rcsents the direction of propagation of the light-ray, each particle of ether vibrates at right angles to this as a line of equilibrium. The vibra- * See further on pp, 177 at seq. 126 PHYSICAL CHARACTERS OF MINERALS. tioii of the first particle induces a similar movement in the adjacent par- ticle ; this is communicated to the next, and so on. The particles vibrate successively fi'om the line AB to a distance corresponding to l>h\ called the arriplitude of the vibration, then return to b and pass on to b'\ and so 374 on. Thus at a given instant there are particles occupying all positions, from that of the extreme distance h' , or c\ from the line of equilibrium to that on this line. In this way the wave of vibration moves forward, while the motion of the particles is only transverse. In the figure the vibrationa are represented in one plane only, but in ordinary light they take place in all directions about tlie line AB. The distance between any two particles, which are in like positions, of like ])hase, as h' and c', is called the wave- length / and the time required for this completed movement is called the tiine of vibration. The intensity of the light varies with the amplitude of the vibrations, and the color depends upon the length of the waves ; the wave-lengths of the violet rays are shorter than those of the red rays. Two waves of like phase, propagated in the same direction and of equal intensity, on meeting unite to form a wave of double intensity (double amplitude). If tlie waves differ in phase by half a wave-length, or a.T odd multijAe of this, they interfere and extinguish each other. For other rela- tions of phase they are also said to interfere, forming a new resultant wave, differing in phase and amplitude from each of the component waves ; if they are waves of wiiite light, their interference is indicated by the appear- ance of the successive colors of the spectrum. The propagation of the vibration -waves of light is sometimes compared to the effect produced when a pebble is thrown in a sheet of quiet water — a series of concentric circular waves are sent out from the point of agitation. These waves con- sist in the transveree vibration of the particles of water, the waves move forward, but the water simply vibrates to and fro vertically. The waves of light are propagated forward, in an analogous manner, in all directions fi-om the luminous point, and the surface which contains all the particles which commence their vibrations simultaneously is called the waves ai'f ace (Wellenflache, GerTU.). If the propagation of light goes on with the same velocity in all direc- tions in a homogeneous medium, the wave-surface is obviously that of a sphere and the medium is said to be isotrope. If it takes place with dif- ferent velocities in different directions in a body, the wave surface is some- times an ellipsoid, but never spherical, as Is shown later; such a )y^dy is called anisotrope. All the phenomena of optics are explained upon the supposition of '>i3ave% of lights whose change of direction accompanies refraction, whose interfer- en(;e produces the colored bands of ■ the diffraction spectra, etc. For the full discussion of the subject reference must be made to works on optics. BEFBACTION JF LIGHT. 127 Refraction. — A ray of light passing through a homogeneous medium ia always propagated in a straight line without deviation. Wtien, however, tiie light-ray passes from one medium to another, which is of different density, it suffers a change of direction, which is called refraction. For in- stance, in f. 375, if ca is a ray of light passing from air into water, its path ■will he changed after passing the surface at «, and it will continue in the direction db. Conversely, if a ray of light, Ja, pass from the denser medium, water, into the rarer medium, air, at a, it will take the direction ac. If now raao is a perpendicular to the sur- face at a, it will be seen that the angle ca?^^, called the angle of incidence {£) of the ray ca is gj-eater than the angle bao, called the angle of refraction (r), and what is observed in this case is found to be universally true, and the law is expressed as follows : A ray of light in jpassing from a rarer to a denner inediuvfi is refracted towards the perpemlicular ^ if from a denser to a rarer medium it is refracted AWAY FROM the jper^endicular. A f uither relation has also been established by experiment : however great or small the angle of incidence, cam- (i), may be, there is always a constant i elation between it and the angle of veiraatiow, ga?n {?'), for two given substances, as here for air and water. This is seen in the figure where af and da are the sines of the two angles, and their ratio (= f nearly) is the same at that of the sine of any other angle of incidence to the sine of its angle of refraction. This principle is expressed as follows: The sine of the angle of incidence bears a constant ratio to the sine of the angle of refraction. This constant ratio between these two angles is called the index of refrac- tion., or simply n. In the example given for air and water sin % sin r i.3::.5, and consequently the value of the index of refraction, or •??., is 1.335. The following table includes the values of n for a variety of substances. For all crystallized minerals, except those of the isometric system, the index of refiaction has more than one value, as is explained in the pages which follow. Ice 1.308 A\^ater 1.335 Fluorite 1.436 Alum 1.457 Chalcedony 1.553 Rock-salt 1.557 Quartz 1.548 Calcite 1.654 Aragonite 1.693 Boracite 1.701 Garnet 1.815 Zircon 1.961 Blende 2.260 Diamond 2.419 III the principle which has been stated, sin X siu/* 71, twc points are to be 128 PHYSICAL CHAI.A.CTERS OF MINERALS. noted. First, if the angle i = 0°, then sin i = 0, and obvioiislj also r = in other words, wlien the ray of light coincides with the perpendicular no refraction takes place, the ray proceeding onward into the second raediuiri without deviation. Again, if the angle i = 90°, then sin i = 1, and the equation above be- comes = n. or sin r = — . As n has a fixed value for every substance, sin /• ' n J J it is obvious that there will also be a corresponding value of the angle r for the case mentioned. From the above table it is seen that for water sin r = :r~^w^'> and r = 4S° 35' ; for diamond, sin r = - — -, and r = 24° 25'. In the example employed above, if the angle bao (r) = 48° 35', the line ac will coincide with ay, supposing the light to go from b to a. If r is greater than 48° 35', the ray no longer passes from the water into the air, but suffers total reflection at the surface a. This value of t is said to be the limiting value for the given substance. The smaller it is the greater the amount of light reflected, and the greater the apparent hrilliancy of the substance in question. This is the explanation of the brilliancy of the diamond. Deteniiinatioti of the index of refraction." — By means of a prism, as MNP in f. 376, it is possible to determine the value of n, or index of refraction of a given substance. The full explanation of this subject belongs to works on optics, but a word is devoted to it here. If the material is solid, a prism must be cut and polished, with its edge in the proper direction, and havino' not too small an angle. If the refrac- tive index of a liquid is required, it is placed within a hollow prism, with sides of plates of glass having both surfaces pai-allel. The angle of the prism, MN P (a), is, in each case, measured in the same manner as the angle between two planes of a crystal, and then the minimum amount of deviation (S) of Q.monochrom.'rfic ray of light passing fi'om a slit through the prism is also determined. The amount of deviation of a ray in passing through the piism varies with its position, but when the prism is so placed that the ray nuikes equal angles with the sides of the prism (^ = i\i. 376\ both when entering and emerging, this deviation has B, fixed minimum value. If S = the minimum deviation of the ray, and sin ^{a + 8) a = the angle of the prism, then n = sm -ka In determining the value of 7i for different colors, it is desirable to employ rays of known position in the spectrum. Douhie refraction. — Hitherto the existence of only one refracted ray has been assumed when light passes from one medium to another. But it is a Avell-kiiown fact that there are sometimes two refi-acted rays. The most familiar example of this is furnished by tlie mineral calcite, also called on account of this property "'doubly-refracting spar." If mnop (f. 377} be a cleavage piece of calcite. and a ray of light raceti * See further on p. 177. REFLECTION, DISPERSION AND DIFKItACTKiX OF LIGHT. 129 it at h, it will, in passing through, be divided into Similarly a line seen througli a piece of ealcite ordi- narily appears donble. it will be seen, however, that the same property is enjoyed/ by the great majority of crystallized minerals, thougii in a less striking degi-ee. Ri'jlection. — When a ray of light passes from one medium to another, for example, from air to a denser substance, as has been illustrated, the light will be par- tially transmitted and refracted by the latter, in the manner illustrated, but a ])ortioii of it (the ray ag^ in f. 375), is always reflected back into the air. Tlie direction of the reflected ray is known in accordance with the following law : The aiujlt's of incidence and reflection are eqical. — In f. 375 the angle cavi is equal to the angle mag. The relative amount of light reflected and transmitted depends upon the angle of incidence, and also upon the transparency of the second medium. If the surface of the latter is not perfectly polished, diffuse reflection will take place, and there will be no distinct reflected ray. Still another important principle, in relation to the same subject, remains to be enunciated : The rays of incidence, reflection, and refraction all lie in the same plane. Dispersion. — Thus far the change in direction which a ray of light sufl^era on refraction has alone been considered. It is also true that the amount of refraction diffei-s for the diflerent colors of which ordinary white light is composed, being greater for i»lue than for red. In consequence of this fact, if a ray of ordinary light pass through a prism, as in f. 376, it will not only be i-efracted, but it will also be separated into its component colors, thus forming the spectrum. This variation for the different colors depends directly upon their wave- lengths; the red rays have longer waves, and vibrate more slowly, and hence suffer less refraction than the violet rays, for which the wave-lengths are shorter and the velocity greater. Interference of light ; diffraction. — AVhen a ray of monochromatic light is made to pass through a nan-ow slit, or by the edge of an opaque body, it is diffracted, and there arise, as may be observed upon an appropriately placed screen, a series of dark and light bands, growing fainter on the outer limits. Their presence, as has been intimated, is explained in accordance with the undulatory theory of light, as due to the interference, or mutual reaction of the adjoining waves of light. If ordinary light is employed, the phenomena are the same and for the same causes, except that the bands are successive spectra. Diffraction gratings, consisting of a series of ex- tremely fine lines very closely ruled upon glass, are employed for the same purpose as the prism to produce the colored spectrum. The familiar phenomena of the colors of thin plates and of Newton's rings depend upon the same principle of the interference of the light waves. This subject ia one of the highest importance in its connection with the optical propejtiea of crystals, since the phenomena observed when they are viewed, under certain circumstances, in polarized light are explained in an analogoua manner. (C(jmpare the colored plate, frontispiece.) 9 130 PHYSICAL Ct A.RACTERS OF lymSTERALS. Polarization hy reflection. — By polarization is understood, in general, that change in the character of reflected or transmitted light whicli dimin- ishes its power of being further reflected or transmitted. In accordance witli the undnlatory theory of liglit a ray of polarized light is one whose vibrations take place in a single plane only. Suppose (f. 378) mn and op to be two parallel mirrors, say simple polished pieces of black glass ; a ray of light, AB, will be reflected from mn in the direction BC\ and meeting op, will be again reflected to D. When, as here, the two mirrors are in a parallel position, the plane of reflection is clearly the same for both, the angles of incidence are equal, and the rays AB and CD are parallel. The ray CD is polarized^ although this does not show itself to the eye direct. Now. let the mirror, op^ be revolved about BG as an axis, and let its position otherwise be un- changed, so that the angles of incidence still remain equal, it will be found that the reflected ' ra}^, CD^ loses more and more of its brilliancy as the revolution continues, and when the mirror, op^ occupies a position at right angles to its former position, the amount of light reflected will be a minimum, the planes of reflection being in the two cases perpendicular to one another. If the revolution of the mirror be continued with the same conditions as before, and in the same direction, the reflected ray will become brighter and brighter till the mirror has the position indicated by the dotted line, o'p\ when the planes of reflection again coincide, and the reflected ray, CD\ is equal iu brilliancy to that previously obtained for the position CD. The same diminution to a minimum will be seen if the revolution is con- tinued 90° farther, and the reflected ray again becomes as brilliant as before when the mirror resumes its flrst position op. In the above description it was asseited that, when the planes of inci- dence of the min-ors were at right angles to each other, the amount of li^ht reflected would be less than in any other position, that is a minimum. For one single position of the mirrors, however, as they thus stand perpendicular to each other, that is for one single value of the angle of incidence, the light will be practically extinguished, and no reflected ray will appear from the second mirror. The angle of incidence, ABIT, for this case is called the angle of polar- ization, and its value varies for different substances. It was shown further by Brewster that : The angle of polarization is that angle whose tangent is the index of refraction of the reflecting substance, i.e., tan i= n. Exactly the same phases of change would have been observed if the apper mirror had been revolved in a similar manner. The flrst mirror is often called the polarizer, the second the analyzer. This change which the light suffers in this case, ir. consequence of re- flection, is called ^J>c^«r^2a^^6'». In order to give a partial explanation of this phenomenon and to make POLARIZATION OF LIGHT. 131 the same subject intelligible as applied to pther cases in which polari;!ation ctccurs, reference must be made to the commonly received theorj' of the nature of light already defined. The phenomena of liglit are explained, as has been stated, on the assump- tion that it consists of the vibrations of the ether, the vibrations being transverse, that is in a plane perpendicular, to the direction in which the light is propagated. These vibrations in ordinary light take place in all directions in this plane at sensibly the same time ; strictly speaking, the vibrations ai-e considered as being always transverse, but their directions are constantly and instantaneously changing in azimuth. Such a ray of light is alike on all sides or all around the line of propagation, AjB, f. 374, A ray of completely polarized light, on the other hand, has vibrations in one direction only, that is in a single plane. These principles may be applied to the case of reflection already de- scribed. The ray of ordinary light, AB, has its vibrations sensibly simul- taneous in all dii-ections in the plane at right angles to its line of propao-a- tion, while the light reflected from each mirror has only those vibrations which are in one direction, at right angles to the plane of reflection — supposing that the mirrors are so placed that the angle of incidence {ABII) is also the angle of polarization. If the mirror occupy the position represented in f. 378, the ray of light, Z> 6', after being reflected by the first mirror, w/i, contains that part of the vibrations whv)S*" direction is normal to its plane of reflection called the plane of polaHz'Mion-. This is also ti'ue of the second mirror, and when they are parallel and their planes of reflection coincide, the ray of light ia I'ellected a second time without additional change. If, however, the second mirror is revolved in the way described (p. 130), less and less of the light will be reflected by it, since a successively smaller part of the vibrations of the ray BC ioke place in a direction normal to its plane of reflection. And when the mirrors are at right angles to each other, after a revolution of oj) 90° about the line BC n,^ an axis, no part of the vibrations of the ray BO ave in the plane at right angles to the reflec- tion-plane of the second mirror, and hence the light is extinguished. By reference to f. 375 this subject may be explained a little more broadly. It was seen that of the ray ea, meeting the surface of the water at a, part is reflected and part transmitted in accordance with the laws of reflection and refraction. It has been shown further that the reflected ray is polar- ized, that is, it is changed so that the vibrations of the light take place in one direction, at right angles to the plane of incidence. It is also true that the 'refracted ray is polarised, it containing only those vibrations which were lost in the reflected ray, that is, those which coincide with the plane of incidence and reflection. It Avas stated that the vibrations of the polarized reflected ray take place at right angles to the plane of polarization. This is the assu'.nption which ia commonly made ; but all the phenomena of polarization can be equally well explained upon the other supposition that they coincide with this plane. The separation of the ray of ordinary light into two rays, one reflected the other refracted, vibrating at right angles to each cthei-, takes place most oompletely when the reflected and refracted rays are 90° from one another, 132 PHYSICAL CHAKACTERS OF MINERALS. as proved by Brewster. Front this fact follows the law aireadj stated, that the tangent of the angle of polarization is equal to the index of re- fraction. Tlie angle of polarization for glass is about 54° 35'. This separation is in no case absolutely complete, but varies with differ- ent substances. In the case of opaque substances the vibrations belonging to the refracted ray are more or less completely absorl.jed (compare remarks on color^ p. 1(38). Metallic surfaces polarize the light very slightly. Polarization by means of thin plates of glass. — It has been explained that the light which has been transmitted and refracted is always at least in part polarized. It will be readily understood from this fact that when a number of glass plates are placed together, the light which passes through them all will be more and more completely polarized as their number is increased. This is a second convenient method of obtaining polarized light. Polarization hj means of tourmaline plates. — The phenomena of polar- ized light may also be shown by means of tourmaline plates. If from a crystal of tourmaline, which is suitably transparent, two sections be obtained, each cut parallel to the vertical axis, it will be found that these, when placed together with the direction of their axes coinciding, allow the light to pass through. If, however, one section is revolved upon the other, less and less of the light is transmitted, until, when their axes are at right angles (90°) to each other, the light is (for the most part) extin- guished. As the revolution is continued, more and more light is obtained through the sections, and after a revolution of 180°, the axes being again parallel, the appearance is as at first. A further revolution (270°) brings the axes again at right angles to each other, when the light is a second time extinguished, and so on around. The explanation of these phenomena, so far as it can be given here, is analogous to that employed for the case of polarization by re- flection. Each plate so affects the ray of light that after having passed through it there exist vibrations in one direction only, and that parallel to the vertical axis, the other vibrationy being absorbed. If now the two plates are placed in the same position, ahdc, and efgh (f. 379), the light passes through both in succession. If, however, the one is turned upon the other, only that portion of the light can pass througli which vibrates still in the direction ac. This portion is determined by the resolution of the existing vibrations in accordance with the princi[)le of the parallelogram of forces. Consequently, when the sections stand at right angles to each other (f. 330) the amount of "^^' transmitted light is nothing (not strictly true), that is, the light is extinguished. The tourmaline plates, which have beeri desci-ibed, are mounted in pieces of cork and held in a kind of wire pincers (f. 381). The object to be examined is placed between them and supported there by the spring in the '' wire. In use they are held close to the eye, and in this position the object is viewed in converging polarized light. Polai'ization hy mea^is of Wicol prisms. — The most convenient method of obtaining polarized light is by means of a Nicol prism of calcite. A POLARIZATION OF LIGHT. 133 cleavage rliombohedron of calcite (the variety Iceland spar is universally used in consequence of its transparency) is obtained, having four large and two small rhouibohedral faces opposite eacli other. In place of the latter 382 t OiH planes two new surfaces are cut, making angles of G8° (instead of 71°) with the obtuse vertical edges ; tliese then form the terminal faces of the prism. In addition to this, the prism is cut through in the direction HH (f. 3S2), the parts then polished and cemented together again with Canada balsam. A I'ay of light, dh^ entering the prism is divided into two rays polarized at right angles to each other. One of these, hc^ on meeting the layer of balsam (whose refractive index is' greater than that of calcite) buffers total retieetion (p. 128), and is deflected against the blackened sides of the prism and extinguished. The other passes through and emerges at 6, a completely polarized ray of light, that is. a ray with vibi-ations in one direction only, and that the direction of the shorter diagonal of the prism (f. 3 S3). It is evident that twoIS'icol pi'isms can be used together in the same wa}' as the two tourmaline plates, or the two mirrors ; one is called the polarizer, and the other the analyzer. The plane of polarization of the Nicol prisms has the direction P P (f. 383) at right angles to which the vibrations of the light take place. A ray of light pass- ing through one Nicol will be extinguished by a second when its plane of polarization is at right angles to that of the first prism ; in this case the Nicols are said to be crossed. The Nicol })risins have the great advantage over the tourmaline plates, that the light they transmit is uncolored and more completelv polarized. Either a tourmaline plate or a Nicol prism may also be used in connection with a reflecting mirror. The light reflected by such a mirror vibrates in a plane at right angles to the plane of incidence (plane of polarization); that trans- mitted by the Nicol prism vibrates in the direc- tion of the shorter diagonal (f. 383). Hence, when the plane of this diagonal is at right angles to the jdane of pcjlarization of the mirror, the re- flected ray will pass through the prism ; but when the two planes mentioned coincide, the planes of vibration are at right angles and the reflected rav Is extinguished by the prism. 383 134 PHYSICAL CHAKACTEES OF MINERALS. Polariscopes* — TlieNicol prisms, when ready for use, are mounted in an upright instrument, called a polariscope. Sometitnes parallel, and some- times cmwerging, light is required in the investigations for which the instru- ment is used. Fig. 384 shows the polarization-microscope of Norrenberg 384 as altered and improved by Groth (see Literature, p. 160). The Nicol prisms are at d and r, and ai-e so mounted as to admit of a motion of revolution in- dependent of the other parts of the in- strument. The lense e causes the light from the ordinary mirror, a, to pass as a cone through the prism d^ and the lenses at A converge the light upon tiie plate to be examined placed at i. The other lenses (o')ab may be less than e, and in this case the velocity of pro- pagation for the light has its maxinuim parallel to the vertical axis. The former are called negative^ the latter positive crystals. The fact alluded to here should be noted that the value of the refractive index is inversely proportional to the velocity of the light, or elasticit}' of the ether, in the given direction. Negative crystals ; Wave-surface. — Forcalcite 03 = 1-654, e = 1'483, it is hence one of the class of negative crystals. The former value (<») belongs to the ray vibrating at right angles to the vertical axis, and the latter value (e) to the ray with vibrations parallel to the axis. As has been stated, the refractive index for the extraordinary ray increases from 1.483 to 1.C54, as the j-ay becomes more and more nearly pai'allel to the vertical axis. Fig. 387 ill us- '^°^ trates graphically the relation between the two indices of I'cfraction, and the correspond- ing velocities of the rays ; ah represents the direction of the vertical axis, that is, the optic axis. Also ma^ tnh repi-esent the velocity of the light parallel to this axis, correspcmd- ing to the greater index of refraction (1"654). The circle described with this radius will represent the constant velocity of the ordi- nary ray in an}' direction whatever. Let further ind., rac represent the velocity of the extraordinary ray passing at right angles to the axis, hence corresponding to the smaller index 'ii refraction (1'483). The ellipse, whose major and minor axes are cd and ah., will express the law in accordance with which the velocity of the extraordinary ray varies, viz., greatest in the direction md., least in the direction ah in which it coincides witli the ordinary ray. For any inter- mediate direction, hgm., the velocity will be expressed by the length of the •ine, hn. Now let this figure be revolved about the axis ah ; there will be geneiated 138 PHYSICAL CHARACTERS OF MINEKAL8. 388 389 a circle witlilii an oblate ellipsoid of rotation (f. 388). The surface ot the sphere is the wave-surface of the ordinary ray and that of the ellipsoid of the extraordinary ray ; the line of their intersection is the optic axis. In f. 377, p. 147, the ray of light is shown divided into two by the piece of calcite ; of these, hd, which is the more refracted, is the ordinary ray, and ho, which is less refracted, is the extraoi'dinary ray. Positive crystals f Wave-surface. — For quartz o) = 1-548, €=1*558. The index of rcfi-action for the ordinary ray (w) is less than that of the extraordinary ray (e) ; quartz hence belongs to the class of positive crystals. The value of e (1'558) for the exti-aordinary ray corresponds to the direction of the ray at J'ight angles to tlie vertical axis, when its vibrations are parallel to this axis. As the direction of the ray changes and becomes more and more nearly par- allel to the axis, the value of its index of re- fraction decreases, and when it is parallel to the latter, it has the value 1*548. The exti-aordin- ary ray then coincides with the ordinary, and there is no double refraction ; tliis is, as be- fore, the line of the 02)tic axis. The law for both i-ays can be represented graphically in the same way as for negative crystals. In f. 389, amh is the direction of the optic axis; let ma, mb represent the velocity of the ordin- ary ray, which corresponds to the least re- fractive index (1'548), the circle afbe will express the law for this ray, viz., the velocity the same in every direction. Moreover, let 7nd, rac i-epresent the velocity of the extraor- dinary ray, at right angles to the axis, which corresponds to the maximum refractive index (1*558); the ellipse, adbc, will express the law for velocity of the extraordinary ray, viz., least in the direction md, and greatest in the direction ah, when it is equal to that of the ordinary ray, and varying uniformly between these limits. If the iigure be revolved as before, there will be generated a sphere, whose surface is the wave-surface of the ordin- aiy ra}', and 'tnithiii it a prolate ellipsoid whose surface represents the wave-surface of the extraordinary ray. The following list includh-s examples of both classes of uniaxial crystals : Negative crystals (— ), Calcite, Tourmaline, Corundum, Beryl, Apatite. Positive crystals (-f ), Quartz, Zircon, Hematite, Apophyllite, Cassiterite. It may be remarked that in some species both + and — varieties ha\e OPTICAL CHAEACTEK8 OF UNIAXIAL CETSTAL8. 139 beeu observed. Certain crystals of apophyllite are positive for ono Olid of tlie spectrum and negative for the other, and consequently for some color between the two extremes it has no double refraction. These principles make the explanation of the use of toui-maline plates and calcite prismi as polarizing instruments (p. 150) more intelligible. The two rays into which the single ray is divided on passing through a uniaxial crystal are, as has been said, both polarized, the ordinary ray in a plane passing through the vertical axis and the extraordinary ray perpendicular to this. In a tourmaline plate of the proper thickness, cut parallel to the axis (', the ordinary ray is absorbed (for the most part) and the extraordinary ray alone passes through, having its vibrations in the direction of the vertical axis. In the calcite prism, of the two refracted and polarized rays, the ordinary ray is disposed of artificially in the manner mentioned (p. 151), and the extraordinary ray alone passes through, vibrating as already remarked, in the dii'ection of the axis J, or, in other words, of the shorter diagonal of the Xicol prism . The relation of these phenomena to the molecular structure of the crystal is well shown by the effect of pressure upon a parallelopiped of glass. Glass, normally, exhibits no colored phenomena in polarized light, since the elasticity of the ether Ls the same in aU directions, and there is hence no double refraction. But if the block be placed under pressure, exerted on two opposite faces, the conditions are obviously changed, the density is the same in the both lateral directions but differs from that in the direction of the axis of pressure. The sym- metry in molecular structure becomes that of a uniaxial crystal, and, as would be expected, on placing the block in the polariscope, a black cross with its colored rings is observed, exactly as with calcite. Similarly when glass has been suddenly and unevenly cooled its molecular structure is not homogeneous, and it will be found to polarize light, although the phenomena, for obvious reasons, inIII not have the' regularity of the case described. It may be added here that recent investigations by Mr. John Kerr have shown that electri* city calls out birefriugent phenomena in a block of glass. (Phil. Mag., 1., 337.) 0])tical Investigation of Uniaxial Crystals. Sections Twrmal or parallel to the axis in polarized light. — Suppose a section to be cut pei'pendicular to the vertical axis (axial section), it lias already been shown that a ray of light passing through the crystal in this direction suffers no change, consequently, such a section examined in parallel polarized light, in the instrument (f. 385), appears as a section of an isometric crystal. If the same section be placed in the other instrument (f. 384, p. 152), arranged for viewing the object in converging light, or in the tourmaline tongs, a beautiful phenomenon is observed ; a symmetrical black cross — • when the Nicols or toiu'maline plates are crossed — with a series of concentric rings, dark and light, in monochromatic light, but in white light, showing the prismatic colors in succession in each ring. This is shown without the colors in f. 390, the arrangement of the colors in the ellijitical rings of the colored plate (trontispieec) is similar. This ci'oss becomes white when the Nicols or tourmalines are in a par- allel [)Csition, and each band of color in white light changes to its complo- mi^nrary tint (f. 391). These interference ligures are seen* in this form onlv in a plate cut perpendicular to the vertical axis, and marks the uni- 'j.xiul character of the crystal. The explanation of this phenomenon can be only hinted at in this place * Uniaxial crystals which produce circular polarization exhibit interference figures which differ somewhat from those described. Some anomalies are mentioned on p. 158. See also pp. 185 et seq. 140 PHYSICAL CHAKACTERS OF MINERALS. A.11 the rajs of light, whose vibrations coincide with the vibration-planea yf either of the crossed Nicols, must necessarily be extinguished. This gives rise to the black cross in the centre, with its arms in the direction of (he planes mentioned. All other rays passing througli the given plate obliquely will be doubly refracted, and after passing through the second Nicol, thus being referred to the same plane of polarization, they will I interfere^ and will give rise to a series of concentric rings, light and dark in homogeneous light, but in ordinary light showing the successive colors of the spectrum. In regard to the interference of polai'ized rays, the fact muFL be stated that that can take place only wlien they vibrate in the same plane ; two rays vibrating at right angles to each other cannot interfere. These interference iDhenomena are similar to the successive spectra obtained by diffraction gratings alluded to on p. 129. It is evident that, in order to observe the phenomena most advantageously, the plate ninst have a suitable thickness, which, however, varies with the refractive index of the substance The thicker the plate the smaller the rings and the more they are crowded together ; when the thickness is considerable, only the black brushes are eeen. Section parallel {or sharply inclined) to the axis. — If a section of a uni- axial crystal, cut parallel or inclined to the vertical axis, be examined in parallel polarized light, it will, M'hen its axis coincides with the direction of vibration of one of the Nicol prisms, appear dark when the prisms are crossed. If, however, it be revolved horizontallv on the stage of the polari- pcope (/, Z, f. 384) it will appear alternately dark and light at intervals of 45°, dark under the conditions mentioned above, otherwise more or less light, the maximum of light being obtained when the axis of the section makes an angle of 45^ with the plane of the Nicol. Between parallel Nicols the l)henomena are the same except that the light and darkness are reversed. When the plate is not too thick the polai-ized ray, after passing the upper Nicol, will intei'fere, and in white light, the plate will show bright colors, which change as one of the Nicols or the plate is revolved. Exirmincd in converging light, similar sections, when xqyj thin, show iu white light a series of parallel colored bands. Dettirmination of the indices of refraction w and e. — One prism will 1 OPTICAL CHAEACTERS OF UNIAXIAL CETSTAJ.S. 141 fiuffioe for the determination of both indices of refraction, and its edge may be either parallel or perpendicular to the vertical axis. (a) If parallel to the vertical axis, the angle of minimum deviation for each ray in succession must be measured. The extraordinary ray vibrates parallel to, and the oi-dinary ray at right angles to, the direction of the edge of the prism. For convenience it is better to isolate each of the rays in succession, which is done with a single Nicol prism. If this is held before the observing telescope with its shorter diagonal parallel to the refracting edge of the prism, the ordinary ray will be extinguislied and the image of the slit observed will be that due to the extraordinary ray. If held with ita plane of vibration at right angles to the prismatic edge, the extraordinary ray will be extinguished and the other alone observed. Fi'om the single observed angle, for the given color, the index of refraction can be calculated, (o or 6, by the formula given on p. 128, the angle of the prism being known. {b) If the refracting edge of the prism is perpendicular to the veitical axis of the crystal, the same procedure is necessary, only in this case the ordinary ray will vibrate parallel to the prismatic edge, and the extraordi- nary j-ay at right angles to it. The two rays are distinguished, as before, by a Nicol prism. Determination of the positive or negative character of the douhle refrao tion. — The most obvious way of determining the character of the double refraction (w > e or &> > e) is to measure the indices of refraction in accord- ance with the principles explained in the preceding paragraphs. It is not always possible, however, to obtain a prism suitable for this purpose, and in any case it is convenient to have a more simple method of accomplishing the result. To do this, use may be made of a very simple principle : — the + or — character of a given crystal is determined by observing the effect produced when an axial sec^tion from it is combined in the polariscope with tbat of a crystal of known character. For instance, calcite is negative, and if it be placed in conjunction with the section of a positive crystal, the whole effect observed is the same as that which would be produced if the original plate were diminished in thickness, while, if combined with a iiegative crystal, it is as if the plate were made thicker. It has already been remarked that, as the axial plate of a ci-ystal increases in thickness, the number of rings visible in the field of the polari- scojte increases, and they become more crowded together ; but, if the section is made thinner, the successive rings widen out and become less numerous. One or the other of these effects is produced by the use of the intervening section. In the case of uniaxial crystals, however, the method which is pj-actically most simple is that sui.'gested by Dove — the use of an axial plate of mica of a certain thickness. The section requii-ed is a cleavage piece of 6uch a thickness that the two rays in passing thi-ongh suffer a diffei-ence of i>liase which is ecpial to a quarter wave-length, or an odd multiple of this. Suppose that the section of the crystal to be examined, cut perpend iculai to the axis, is brought between the crossed Nicols in the polaristxype ; the black cross and the concentric colored j'iiigs are of course visible. Let now, while the given section occupies this position, the mica plate be placed upon it, with the plane of its optic axes (determined beforehand, and the direction 142 PHYSICAL CHARACTERS OF MINERALS. marked by a line for convenience) making an ano:le of 45° with the vibrar tion-planes of the Xicols ; the black cross' disappears and there remain only two diagonally situated dark spots in the place of it. Moreover, the colored «Mii'ves in the two quadrants with these spots are pushed farther away from tiie centre than the others. The effect produced is represented in f. 392 and f. 393. If the line joining these two dark spots stands at right angles 392 393 to the axial plane of the mica, the crystal is positive (f. 392), if this line coincides with the axial plane, the crystal is negative (f. 393). The explana- tion of this cf ■ '^ is not so simple as to allow of being introduced here ; the effect of the iiiii;a is to produce circular polarization of the light which it transmits. With both uniaxial and biaxial crystals the student will find it of great assistance always to have at his side a good section of a positive and a negative crystal. By comparing the phenomena observed in the section under examination with those shown by crystals of known character, he will often be saved much perplexity. For the investigation of the dbsorjption phenomena of uniaxial crystals see p. 165. Circular Polarization. In what has been said of polarized light, in the preceding pages, it has been assumed that a polarized ray was one whose vibrations took place in a single plane, so that the plane of polarization at right angles to this was a fixed plane. Such a ray is said to be linearly polarized. There are some uniaxial ciystals, however, which have the power to rotate the [ilane of polari- zation ; the ray is said to be circularly polarized. They manifest this in the phenomena observed when an axial section is examined in the poluriscope. An axial section of a uniaxial crystal normally exhibits, in converging olarized light, a black cross with a series of concentric colored circles, , 390, p. 140. If, however, a section of quartz be cut perpendicular to the axis and viewed between the crossed Nicols, tiie phenomena observed are different from tl.ese: — the central portion of the black cn^ss has disap- peared, and instead, the space within the inner ring is brilliantly colored. Furthermore, when the analyzing Kicol is revolved, this color changes from blue to yellow to red, and it ia found that in some cases thia I CIRCULAR POLARIZATION. 143 change is produced by revolving the Nicol to the right, and in other casea to the left. To distinguish between these the first are called i-ight-handed rotating (;rystals, and the others left-handed. The relations here involved will be better understood if the quartz section is viewed in parallel mono- chromatic light. Under these circumstances a similar plate of calcite appears dark when the Nicols are crossed, but with quartz the maximum darkness is only obtained when the analyzer has been revolved beyond its first position a certain angle ; this angle increasing with the thickness of the section, and also varying with the color of the light employed. For a section 1 mm. thick in red light, a rotation of the analyzer of 19° is required to produce the maximum darkness. For yellow light the rotation is 24° with a plate of the same thickness ; with blue, 32°, and so on. The rotation of the analyzer with some crystals is to the right, with others to the left. The explanation of these facts lies in the fact stated above, that the quartz rotates the plane of vibration of the polai-ized light, and the angle of rotation is different for juys of different M'ave-lengths. Further'.nore, this rotation of the phme of vibration results from the fact that in quartz, even in the direction of its axis, double refraction takes place. The oscillations of the particles of ether take place not in straight lines but in circles, and they move in opposite dii'ections for the two rays, ordinary and extraor- dinary. An axial section of a quartz crystal can never appear dark between crossed Nicols in ordinary light, since there is no point at which all the colors are extinguished ; on the contrary, it appears highly colored. The color depends upon the thickness of the section, and is the same as that observed in the centres of the rings in converging polarized light. If sec- tions of a right-handed and left-handed crystal are placed together in the polariscope, the centre of the interference figure is occupied with a four- rayed spiral curve, called from the discoverer Airy's spiral. Twins of quartz crystals are not unconmion, consisting of the combination of right- and left-handed individual, which sometimes show the spirals of Airy. It is a remarkable fact, discovered by Herschel, that the right- or left- handed optical character of quartz is often indicated by the position of the trapezohedral planes on the crystals. When a given trapezohedral plane appeal's as a modification of the prism, to the right above and left below, the crystal is optically right-handed ; if to the left above and right below, the crystal is left-haivlel. In f . 394 the plane is, as last remarked, left above and right below, and the crystal is hence left-handed. Cinnabar has been shown by Des Cloizeaux to possess the same property as quartz; and this is true also of some artificial salts, also solutions of sugar, etc. In twins of quartz, the component parts may be both right-handed or both left-handed (as in those of Dauphiny and the Swiss Alps) ; or one may be of one kind and the other of the other. Moreover, successive layers of deposition (made as the crystal went on enlarging, and often exceedingly thin) are sometimes alternately right- and left-handed, showing a constant oscillation of polarity in the course of its formation ; and, M'hen this is the ease, and the layers are regular, cross-sections, examined by polarized light, exhibit a division, more or less perfect, into sectors of 120°, parallel to the plane R, or intc sectors of 6o°. If the layers are of unequal thickness 144 PHYSICAL CHARACTERS OF MINERALS. there are broad areas of colors without sectors. In f. 395 (by Des Cloizeaux, fi'om a crystal from the Dept. of the Aude), half of each sector of G0° is 894 395 right-handed, and the other half left (as shown by the arrows), and the dark radii are neutral bands produced by the overlapping of layers of the twc kinds. These overlapping portions often exhibit the phenomenon of Airy'e spiral. C. Biaxial Crystals. General 0_ptical Character. As in the crystalline systems, thus far considered, so also in the anisome- trio systems, the orthorhombic, monoclinic, and triclinic, there is a strict corre- spondence between the molecular structure, as exhibited in the geometrical form of the crystals, and their optical properties. In the crystals of these systems there is no longer one axis around about which the elasticity of the light-etber, that is, the velocity of the light, is everywhere alike. On tiie contrary, the relations are much less simple, and less easy to comprehend. There are two directions in which the light passes through the crystal without double refraction — these are called the optic axes, and hence the crystals are hiaxial — but in every other direction a ray of light is separated into two rays, polai'ized at light angles to each other. Neither of these conforms to the law of simple refraction. The subject was fii-st developed theoretically by Fresnel, and his conclusions have since been fully verified by experiment. Axes of elasticity. — In regard to the elasticity of the ether i!i a biaxial crystal there are (1) a maximum value, (2) a minimum value, and (3) a mean value, and these values in the crystal are found in directions at right angles to each other. In f. 396, CC represents the axis "(c) of least elasticity, AA' of greatest elasticity (a), and BB' of mean elasticity (b). A ray passing in the direc- OPTICAL CHAEA0TEK8 OF BIAXLAL CRYSTALS. 145 Hon CC vibrates in a plane at right angles, that is, parallel to BB' and AA' . Similarly for the ray BB' the vibrations are parallel to AA' and GC\ and for the ray AA! parallel to BB' and CC . Between these extreme values of the axes of elasticity, the elasticity varies according to a re<'ular law, as will be seen in the following discnssion. The form of the wave-surface for a biaxial crystal may be determined by fixing its form for the planes of the axes a, b, and c. Wave->iiirface. — First consider the case of rays in the plane of the axf.^a BB' and CC (f. 397). A ray pass- ing in the direction BB' is separated into two sets of vibrations, one paral- lel to AA\ corresponding to the greatest elasticit}^ moving more rupidlv than the other set, parallel to CG\ which correspond to tlie least elasticity. The velocities of the two sets of vibrations are made pro- portional to the lengths of the lines mn^ and mo respectively, in f. 397. Agiiin, for a ray in the same plane, parallel to CC, the vibrations are (1) parallel to AA^ and propagated faster (greatest elasticity) than the other set; (2) parallel to BB (mean elasticity). Again, in f. 397, on the line 6'6", wm", and mq^' are made proportional to these two velocities ; here mn = inn" ^ and for a ray in the same plane in any other direction, there will be one set of vibrations parallel to AA! ^ with the same velocity as before, and another set at right angles with a velocity between mo and mq^' ^ determined by the ellix^se whose semi-axes are proportional to the mean and least axes of elasticity. Fig. 397 then represents the section of the wave-surface through the axes CC and BB'. The circle mi!' shows the constant velocity for all vibrations par- allel to AA ^ and the ellipse the variable values of the velocity for the other set of vibrations at right angles to the first. Again, for a ray in the plane AA' , BB , the method of the construction is similar. The vibrations will in every case take place in the plane at right angles to the direction of the ray, which plane nuist always pass through the axis CC of least elasticity. Hence for every direction of the ray in the plane men- tioned, one set of vibrations will always be parallel to CC, and hence be propagated with a constant vtrlocity 10 146 PHYSICAL CHAKACTEB8 OF MINERALS. = mo\ f . 398), and hence this is expressed by the circle oo'. The other set of vibrations will be at right angles to CC'^ and the velocity with which they are propagated will vary according as they are parallel to AA' (= onn, f. 398), or parallel to BE' {— mq')^ or some intermediate value for an intermediate position. The section of the wave-surface is consequently a circle within an ellipse. Finallv,lettheraypassin somedirection in the plane CC\AA\oi least and greatest elasticity, the section of the wavesui-face is also a circle and ellipse. Suppose the ray passes in the direction parallel to AA'^ the vibrations will be (1) parallel to CC\ and (2) parallel to BB', those (1) parallel to 6'6" (least axis of elasticity) are propagated more slowly than those (2) parallel to BB' (axis of mean elasticity). In f. 399, on the line AA\ lay off mo' and mq' proportional to these two values. Again, for a ray parallel to CC the vibrations will take place (1) parallel to AA', and (2) pai-allel to BB', the former will be propagated with gi-eater velocity than those latter. These two values of the velocity in the direction CV are represented by inn" and mq" {= mq'). For any intermediate position of the ray in the same plane there will always be one set of vibrations parallel to BB' [mq' = m,q", f. 399, hence the circle). The other set at right angles to these will be propagated with a velocity va- rying according to the direction, from that corresponding to the least axis of elasticity (represented by mo', f. 399), to that of the greatest axis of elasticity {mn"). OjpHc axes. — It is seen that the cir- cle, representing the uniform velocity of vibrations parallel to b, and the ellipse representing the varying value of the velocity for the vibrations at right angles to these, intersect one an- other at P, F', f. 399. The obvious meaning of this fact is that, for the directions mP, and mP', making equal angles with the axis CC, the velocity is the same for both sets of vibrations ; these are not separated from each other, the ray is 7iot doubly refracted, and not polarized. Those two dire(;tions are called the optic axes. All anisometric crj stale have, as has been stated, two optic axes, and arc hence called biaxial. OPTICAL CHARACTERS OF BIAXIAL CRYSTALS. 147 The complete wave-surface of a biaxial crystal is constructed from the tliree sections given in f. 397, 39S, 399. It is*" shown graphically in f. 400, where the lines PP, and P' P' are the two optic axes. Bisectrices, or Mean-lines. — As shown in f. 399, the optic axes always lie ill the plane of greatest (a) and least (c) elasticity, and the value of the optic axial angle is known when the axes of elasticity are given as stated below. The axis v)f elasticity which, as the line CC", f. 399. bisects the acute angle is called the acute hisectrix, oy first mean-line (erste Mittellinie, Germ.), and that bisecting the obtuse angle, the obtuse bisectrix, or second mean-line (zweite Mittellinie, Gerrn.). Positive and negative crystals. — When the acute bisectrix is the axis of least elasticity (c), it is said to be ^positive, and when it is the axis of greatest (a) elasticity, it is said to be negative. Barite is positive, mica negative. Indices of refraction. — It has been seen that in uniaxial crystals there are two extreme values for the velocity with which light is propagated, and corresponding to them, and inversely proportional to them, two indices of refraction. kSimilarly for biaxial crystals, where there are three axes of elasti- city, there are three indices of refraction — a maximum index a, a minimum 7, and a mean value ;3 ; a is the index for the rays propagated at right angles to a, but vibrating parallel to n ; yS is the index for rays propagated perpen- dicularly to b, by vibrations parallel to b ; 7 is the index for rays propagated perpendicularly to c, but vibrating parallel to c. a = — , y8 = — , 7 = -. If a, 13, and 7 are known, the value of the optic axial angle (2 V) can be calculated from them by the following formula : cos V = J)isj)ersion of the optic axes. — It is obvious that the three indices ol refraction may have different values for the different colors, and as the angle of the optic axes, as explained in the last paragraph, is determined by these three values, the axial angle will also vary in a corresponding manner. This variaticm in the value of the axial angle for rays of different wave lengths is called the dispersion of the axes, and the two possible cases are distinguished by writing p > v when the angle for the red rays (p) is greater than for the blue (violet, u), and p < v when the reverse is true. In the properties thus far mentioned, the three systems are alike ; in details, however, they differ widely. Practical Investigation of Biaxial Crystals. Interference figures. — A section cut perpendicular to either axis will show, in converging polarized light, a system of concentric i-ays analogous to those of uniaxial crystals, f. 390, but more or less elliptical. There is, moreover, no black cross, but a single black line, which changes its position as the ISicols are revolved. '1 1 w 7 1 1 ^ 7 148 PHYSICAL CHAKACTERS OF MINERALS. If a section of a biaxial ciystal, cnf. perpendicularly to the first, that ih acute, bisectrix, is viewed in the polariscope, a difi'ereut phenomenon is observed. There are seen in this case, supposing the plane of the axes to make an angle of 45° with the planes of polarization of the crossed Nicols, two black hyper- Uilas, marking the position of the axes, a series of elliptical curves surrouDd- ing the two centres and finally uniting, foi-uiing a series of lenniiscate.-. If monochromatic light is employed, the i-ings are alternately light uud dark; if white light, each riug shows the successive colors of the spectruui. If one of the iS'icol prisms be revolved, the dark hyperbolic brushes gi-adu- ally become white, and the colors of the rings take'the complementary tints after a revolution of 90°. Since the black hypei-bolic brushes mark the position of the opiic axes, the smaller the axial augle the nearer together are the hyperbolas, and when the angle is very small, the axial figure observed closely resembles the simple cross of a imiaxial crystal. On the other hand, when the axial angle is lai'ge the hyperbolas are far apart, and may even be so far apart as to be invisible iu the field of the polariscope. When the plane of the axes coincides with the plane of vibi'ation foi either Nicol, these being crossed, an unsynnuetrical black ci'oss is observed, and also a series of elliptical curves. Both these figures are well exhibited on the frontispiece ; the one gradually changes into the other as the crystal-section is revolved in the horizontal plane, the Xicols lemainiug stationaiw. A section of a biaxial crystal cut perpendicular to the obtuse bisectrix will exhibit the same figures under the same conditions in polarized light, when the angle is not too large. This is, however, generally the case, and in consequence the axes suffer total rpjiection on the inner surface of the section, and no axial figures are visible. This is sometiuies ihe case also OPTICAL CHARACTERS OF BIAXIAL CRYSTALS. 119 with a section cut normal to the acute bisectrix, when the angle is large. A uiicroineter scale in the polariscope, f. 384, allows of an approximate measurement of the axial angle ; the value of each division of the scale being known. Measurement of the axial avgle.'^ — The determination of the angle made by the optic axes is of the highest importance, and the method of prcjce- dure ofi'ers no great difficulties. Fig. 401 shows the instrument recom- mended for this purpose by DesCloizeaux ; its general features will be understood without detailed description ; some improvements have been introduced by Groth, which make the instrument more accurate and con- venient of use. The section of the crystal, cut at right angles to the bisec- trix, is held in the pincers at c;, with the plane of the axes horizontal^ making an angle of 45° with the plane of vibration of the Nicols (iVTV). There is a cross- wire in the focus of the eye-piece, and as the pincers hold- ing the section are turned by the screw F, one of the axes, that is one black hyperbola, is brought in coincidence with the vertical cross-wire, and then, by a 403 further revolution of F, the second. The jb' angle which the section has been turned ^ j ^ v, or p < v) can be seen immediately from the figure of the axes, as in f. la, \h, in the colored plate, f (f rontispi<;ce). It is obviously true in this case, from f. la, as also f . 1^, that the angle for the blue rays is greater than that lor the red (p < -c), and so in general. This — B» same point is also accurately deterinined, of course, by the measni-ed angle for the two monochromatic colors. In all cases the same line will be the bisectrix of the axial angle for both bine and red rays, so that the position of the respective axes is symmeti-ical with icfer- ence to the bisecti-ix. In f. 403, the dis- f»ersion of the axes is illustrated, where p < v\ it is shown also that the ines, j5^ 7?^ and ^^ ^^, bisect the angles of both red {pOp') and blue {vOv') rays. It also needs no further -explanation that for a certain relation B» DISTmOmSHINO OITICAL CHARACTERS OF MONOCLINIO CRYSTALS. 153 )f the refractive indices of the different colors, the acute bisectrix of the axial angle for red rajs may be the obtuse bisectrix for the angle for blue i-ays. Indices of refraction, etc. — The determination of the indices of refrac- tion and the character (+ or — ) of the acute bisectrix is made for ortho- rhombic crystals in the same way as for all biaxial crystals (p. 150). It is merely to be mentioned that, since the axes of elasticity always coincide with the crystallographic axes, it will happen not infrequently that crystals without artificial preparation will furnish, in their prismatic or dome series, prisms whose edges are parallel to the axes of elasticity, and consequently at once suitable for the determination of the indices of refriaction. Distinguishing Optical Characters op Monoclinic Crystals. Position of the axes of elasticity. — In crystals belonging to the mono- clinic system one of the axes of elasticity always coincides with the ortho- diagonal axis h^ and the other two lie in the plane of symmetry at riglit angles to this axis. Here obviously three cases are possible, according to which two of the axes, a, b, or c, lie in the plane of symmetry. Corresponding to these three positions of the axes of elasticity, there may occur three kinds of dispersion of these axes, or dispersion of the hisectrices. This dispersion arises from the fact that, while the position of one axis of elasticity is always fixed, the position of the other two is indeterminate and for the same crystal may be different for the different colors, so that the bisectrices of the different colors may not coincide. Dispersion of the hisectrices. — 1. The bisectrices, that is, the axes of greatest and least elasticity, lie in the plane of sym- metry, while the orthodiagonal axis h coincides with b. The optic axes here suffer a dispersion in this plane of symmeti-y, and, as ah'eady stated, they do not lie symmetrically with reference to the acute bisectrix. This is illustrated in f. 404, where MM is the bisec- trix for the angle, vOv', and BB for the angle pOp'. This kind of dispersion is called by DesOloizeaux inclined (dispersion inclinee). 2. The second case is that where the plane of the optic axes is perpendicular to the plane of symmetry, and the acute bisectrix stands at right angles to the orthodiagonal axis b. In other words, the acute bisectrix and the axis of mean elasticity both lie in the |)lane of symmetry. In this case also dispersion of the axes may take place, and in this way — the plane of the optic axes for all the colors lies parallel to the orthodiagonal, but these planes may have different inclinations to the ve 'tical axis. This is called horizontal dispersion by DesCloizeaux. 3. Still again, in the thii-d place, the plane of the optic axes lies pcrpen dicular to the j)lane of symmetry ; but in this case the acute bisectrix is pai'allel io the crystallographic axis b, so that the obtuse bisectrix and axis of mean elasticity' lie in the plane of symmetry. The dispersion whicli 154 PHTSICAL CHARACTERS OF MINERALS. results in this case is called by DesCloizeaiix crossed (dispei-siou touniante or croisee). Dispersion as shown in the interference figures. — If an axial section of a monoclinic ciystal be examined in converging polarized light, the kind of dispersion which characterizes it will be indicated by the nature of tlie intei-ference figures observed ; the three cases are illustrated by the figure? upon the frontispiece, taken from DesCloizeaux. (frontispiece). Figs. ]«, 15 represent the interference figures for an orthorhombic crystal (nitre), characterized b}^ the symmetry iii the size of the rings, and the distribution of the colors. Figs. 2a, 2(5'(diopside), 3a, Zb (orthoclase), 4a, 45 (borax), arc examples of the corresponding figures for monoclinic crystals, characterized as such more or less distinctly by the want of symmetry in the size of the rings about the two axes, and the irregularity in the arrange- ment of the colors. (1) Inclined disjpersion. — Where the axes are not symmetrically situated with reference to the acute bisectrix. The relation of the two axial figures is illustrated by f. 405. In f. 2a, 25 this kind of dispersion is indicated by 405 407 the position of the red and blue at the centres of the rings, and on the borders of the hyperbolas, compare f. la, \b of the normal figure, where there is no dispersion of the bisectrices. (2) Horizontal dispersion.^ where the planes of the optic axes for the different colors make different angles with the axis. — This is illustrated by f. 406. The effect upon the interference figures is seen in f. 3a, 35 of the plate, by comparing tlie colors within the rings (f. 3a), and on the borders of the hyperbolas (f. 35), with f. la, 15. (3) Crossed dispersion^ where the acute bisectrix coincides with the crystallographic axis 5. — This is illustrated in f. 407, and the interference figures belonging to this kind of dispersion are seen in f, 4a, 45 of the plate, compared as before with la, 15, and with the other figures. Practical Optical Investigation of Monodinic Crystals. Determination of the position of the axes of elasticity, that is, the direc- tions of vibration. Stauroscope. — The position of one axis of elasticity is alone known, since, as has been stated, it coincides with the crystallographic axis 5. In order to determine the position of the other axes in the plane of sj-mmetrj, where they necessarily lie, use is made of an instrument, fii'st proposed by von Kobell, called the Stauroscope. The principle ol this instrument is very simple. Suppose that the two Nicols in the polari- Bcope (f. 385) have their planes of polarization crossed, causing the maxi- mum extinction of light. Now, if a section of any biaxial crystal is biought nSTINGinSHING OPTICAL CHARACTERS OF MONOCLLNIO CRYSTAlfl. 155 408 between them, obviously, if the position of its two rectangular axes oi elasticity, which are its two directions of vibration, coincide with those of the two Nicols, it will produce no change in appearance ; the field of the polariscope, which was dark before, remains dark. But suppose, on the other hand, that it is placed in any other position in the plane, so that its two rectangular directions of vibration do not coincide with those of the Nicols, the field is no longer dark, but more or less light. The reason I'oi this is, that the light from the lower Nicol meeting the crystal plate ia separated, according to the law of the parallelogram of forces, into two seta of vibrations, which are again resolved by tlie analyzing Nicol, and only one set extinguished by it. If, however, the plate be gradually changed in posi- tion, that is, revolved horizontally, nntil its vibration-dii-ections (axes of elasticity) coincide wMtli those of the Nicols, then, as at first, the light is ex- tinguished. If the angle is measured which it is necessar3' to revolve the section to accomplish the result just remarked, that will be the angle be- tween the direction of one of the axes of elasticity of the plate in its oi-igiua) position and the vibration-plane of the Nicol. In figure 40S, let the tM'o larger rectangular arrows represent the vibration- directions for the two Nicols, and between the two prisms suppose a section of a monoclinic crystal, abcd^ to be placed so that one edge of a known crys- tallographic j)lane {eg.^ i-i) coincides with one of these lines. The field of the microscope, dark before, since the prisms were crossed, is no longer so, and becomes dark again, as explained, only when the crystal is i-evolved so that its vibration-directions (the sniallei" dotted arrows) coincide with those of the isicols, which is indicated by the maximum extincrion of the light. The crystal has then the position a'b'c'd'. The angle (f. 408), which it has been necessary to revolve the plate to obtain the efi^ect described, is the angle which one of the axes of elasticity in the given plate makes with the given crystallographic edge i-i. The preceding explanations cover everything that is essential in the Staurosco])e ; but a variety of improvements have been introduced, M-hich practically make the measuremeuts by means of the instrument much more easy and accurate. It will 1)0 seen that the most important feature is the point where the maximum extinction of the light occurs ; this, however, is not easy for the eye to decide upon, and if the trial is made, it will be found that the change produced by a revolution of several degrees is hardly perceptible. To overcome this difficulty, von Kobell proposed to introduce a secttion of cal- cite iust below the analyze]-, because its interference fiirure ijives a better opportunity to judge of a change in the intensity of the light. A stiil better plan is to introduce a composition plate of calcite, as proposed by Ihezina, giving a peculiar interference figure, a very slight change in which destroys its synunctry, and it takes its normal form onlv when the plaues of polariza tion of the two Nicols are exactly at right angles. Supposing this to be the case, when the crystal has been introduced the iutei'ference figure is disturbed, it return 5 to its normal appearance only when the crystal has been revolved d" 156 PHYSICAL CHARACTERS OF MINERALS. 409 to the point where the vibration-directions of the Nicols and crystal section exactly coincide.* It. will be observed ao;ain, that it is essential that the direction of the known edge of the crystal should be exactly parallel to the vibration -direc- tion of one of the Nicols. This condition, in the case of small crystals especially, is hard to fulfil, and to accomplish it most satisfactorily Grotli has proposed to use the plate shown in f. 409. The plate of glass, v, held in its present position by the spring, has one edge polished, which adjoins u, and the direction of this is made to coincide exactly M'ith the line joining the opposite zero points of the gradua- tion. The crystal section is attached to this plate over the hole seen in v, and with a phine of known crystallographic position, either O, i-l or a plane in that zone or a corresponding edge, coinciding with the direction of the polished edge of the plate. Whether this coincidence is exact can be tested by the reflective goniometer. In order to eliminate any small error, Groth pro- poses to measure the divergence from the exact coincidence, and then to make a corresponding correction, for which he furnishes a series of tables. After tlie adjustment of the crystal section on the plate, the latter is inserted in its place, the whole plate, I, k, occupying the position indicated in f. 385, and the Nicols so adjusted that the plane of vibration of one coincides with the line 0° to ISO"". The angle of revolution of the plate, I, is obtaiiied fi'oin the graduated scale on k. It is not always easy to make tlie adjustment of the Nicols alluded to, but the error arising when the vibration-plane of the iNicol does not coincide with the line 0° to 180° is easily eliminated. This is accomplished by remov- ing the plate v, and, without disturbing the crystal section, restoring it to its place in an inverted position. The measured angle, if before too gi-eat, will now be as much too small, and the arithmetical mean of the two measuremente will be the true angle. Reference further may be made to Groth, Pogg. Ann., cxliv., 3-i, 1871. Determination of the j!?Za/i(? of the oj)tij>le-green, : light green with some yellow ; chryso- prase. — 7. Grass-green : bright green with more yellow ; gi-een diallage. — 8. Pistachio-green : yellowish green with some brown ; epidote. — 9. Asjya- ragus-green : pale green with much yellow ; asparagus stone (apatite). — • 10. Blacldsh-green : serpentine. — 11. Olive-green: dark green with much brown and yellow; chrysolite. — 12. Oil-green: the color of olive oil; beryl, pitchstone. — 13. Siskin-green : light green, much inclining to yellow; uranite. F. Yellow. 1. Stdjphitr-yellow : sulphur. — 2. Straw-yellow: pale yel- low ; topaz. — 3. Wax-yelloio : grayish yellow with some brown ; blende, opal. — 4. Honey-yelloio : j^ellow with some red and brown ; calcite. — 5. Lemon-yellow: sulphur, orpiment. — 6. Ochre-yellow: yellow with brown ; yellow ochre. — 7. Wine-yellow : topaz and tluorite. — 8. Cream-yellow : some varieties of lithomarge. — 9. Orange-yellow : orpiment. G. Red. 1. Aurora-red: red with much yellow; some realgar. — 2.. ITyaci.nth-red : red with yellow and some brown ; hyacinth garnet. — 3. Brick-red: polyhalite, some jasper. — 4. Scarlet-red: bright red with a tinge of yellow ; cinnabar. — 5. Blood-red: dark red with some yellow ; pyrope. — 6. Flesh-red: feldspar. — 7. Carmine-red: pure red; ruby sap- phire. — 8. Rose-red: rose quartz. — 9. Crimson-red: ruby. — 10. Peach- blossom-red: red with white and gray; lepidolite. — 11. Columbine-red: deep red with some blue; garnet. — 12. Cherry-red : dark red with some blue and brown : spinel, some jasper. — 13. Brownish-7'ed : jasper, limonite. II. Brown. 1. Reddish-hrown : garnet, zircon. — 2. Clove-brown : hroww with red and some blue ; axinite. — 3. Hair-b^^own : wood opal. — 4. Broc- coli-brown: brown, with blue, red, and gray ; zircon. — 5. Chestmbt-brown : pure brown. — 6. Yellowish-brown: jasper. — 7. Pinchbeck-brown: yellow- ish-brown, with a metallic or metallic-pearly lustre ; several varieties of talc, brouzite. — 8. Wood-brown : color of old wood nearly i-otten ; some specimens of asbestus. — 9. Liver-brown : brown, with some gray and green j jasper. — 10. Blackish-brown ; bituminous coal, brown coal. c. Peculiarities in the Arrangement of Colors. Play of Colors. — An appearance of several prismatic colors in rapid ?u(;cession on turning the mineral. This property belongs in perfection to the diamond ; it is also observed in precious opal, and is most brilliant by candle-light. 164 PHYSICAL CHAEACTER8 OF MmERALS. Change of Colors. — Each particular color appears to pervade a largei fepace tlum in the play of colors, and the succession produced by tinning the mineral is less rapid ; Ex. labradorite. Opalescence. — A milky or pearly reflection from the interior of a speci- men. Observed in some opal, and in cat's eye. Iridescence. — Presenting prismatic colors in the interior of a crj^stal. The plienomena of the play of colors, iridescence, etc., are sometimes to be explained by the presence of minute foreign crystals, in parallel positions ; more generally, howevei-, they are caused by the presence of fine cleavage lamellae, in the light reflected from which interference takes place, analogous to tlie well-known Newton's rings. Tarnish. — A metallic surface is tarnished, when its color differs from that obtained by fracture ; Ex. bornite. A surface possesses the steel tar- nish., when it presents the superficial blue color of tempered steel ; Ex. columbite. The tarnish is irised., when it exhibits fixed prismatic colors ; Ex. hematite of Elba. These tarnish and ii-is colors of minerals are owing to a thin surface film, lu-oceeding from different sources, either from a change in the surface of the mineral, or foreign incrustation ; hydrated iron oxide, usually formed from pyrite, is one of the most common sources of it, and produces the colors on anthracite and hematite. Asterism. — This name is given to the peculiar star-like rays of light observed in certain directions in some minerals by reflected or transmitted light. This is seen in the form of a six-rayed star in sapphire, and is also well shown in mica from South Burgess, Canada. In the former case it has been attributed by Yolger to a repeated lamellar twinning ; in the other case, by Rose, to the presence of minute inclosed crystals, which are a uniaxial mica, according to DesCloizeaux. Crystalline planes, which have been artificially etched, also sometimes exliibit asterism. In general the phenomenon is explained by Schrauf as caused by the interference of the light, due to fine striations or some other cause. (Upon the above subjects, see Literature, p. 16T.) Phosphorescence. Phosphorescence,* or the emission of light by minerals, may be produced in different ways : hy friction, by heat, or by exjyosure to light. By friction, — Ligiit is readily evolved from quartz or wliite sugar by the friction of one piece against another, and mci-ely the rapid moti(m of a feather will elicit it from some specimens of sphalerite. Friction, however, evolves light from a few only of the mineral species. By heat. — Fluorite is highly phosphorescent at the temperature of oOO° F. Different varieties give ofl^ light of different colors ; the chlorophane variety, an emei'ald-green light ; others purple, blue, and reddish tints. This phos- phorescence may be observed in a dark place, by subjecting the pulverized miuei'al to a heat below redness. Some varieties of white limestone oi marble emit a yellow light. * This subject has been investigated by Becquerel, Ann. Ch. Phys., III., Iv., 5-119, 1859; Faster, Mitth. nat. Ges. Bern, 1 807, 62; B.ndi-Hahn, Zeitsch. Ges. nab. Wiss. Berlin, II., be, 1,131, 1874. DIAPHAlOirrr^-COLOK — LUSTRE. Ig5 By the application of heat, minerals lose their phosphorescent properties. But on passii.t,' electricity through the calcined mineral, a more or less vivid li^ht is produced at the time of the discharge, and subsequently the specimen when heated will often emit light as before. The lighi; is usually of the same color as previous to calcination, but occasionally is quite different. It is in general less intense than that of the unaltered mineral, but is much increased by a repetition of the electric discharges, and in some varieties of fluorite it may be nearly or quite restored to its former brilliancy. It has also been found that some varie- ties of tluorite and some specimens of diamond, calcite, and apatite, which are not naturally phosphorescent, may be rendered so by means of electricity. Electricity will also increase the natural intensity of the phosphorescent light. Light of the sun. — The only substance in which an exposure to the liglit of the sun produces very apparent phosphorescence is the diamond, and some specimens seem to be destitute of this power. This property is most striking after exposure to the blue rays of the spectrum, while in the red rays it is rapidly lost. rLEOCHKOISM. Dichroism^ Trichroism. — In addition to the general phenomena of color, which belong to all minerals alike, some of those which are ci-ystallized show different colors under certain circumstances. This is due to the fact that in them the absorption of parts of the spectrum takes place unequally in different directions, and hence their color by transmitted light depends upon the direction in which they are viewed. This phenomenon is called in sreneral pleochroism. tn uniaxial crystals it has been seen that, in consequence of their crystal- lographic symmetry, there are two distinct values for the velocity of light transmitted by them, according as the vibrations take ^^X^cq, parallel or at right angles to the vertical axis. Similarly the crystal may exert different degrees of absorption upon the rays vibrating in these two directions. For example, a transparent crystal of zircon looked through in the direction of the vertical axis appears of a pinkish-brown color, while in a lateral direc- tion the color is asparagus-green. This is because the rays (extraordinary) vibrating jparallel to tlie axis arc absorbed with the exception of those which together give the green color, and those vibrating laterally (ordinary) are absorbed except those which together appear pinkish-brown. Again, all crystals of tourmaline in tlie direction of the vertical axis are opaque, since the ordinary ray, vibrating normal to the axis c, is absorbed, while liglit-colored varieties, looked through laterally, are transparent, for the extraordinary ray, vibrating parallel to c, is not absorbed ; the color differs in different varieties. Thus, ail uniaxial crystals may be dichroic^ or have two distinct axial colors. Similarly all biaxial crystals may be trichroic. For the rays vibratino- in the directions of the three axes of elasticity may be differently absorbed. For diaspore the three axial colors are azure-blue, wine-yellow, and violet- blue. It will be understood that, while these three different colors are pos- sible, they may not exist ; or only two may be prominent, so that a biaxial mineral may be called dichroic. In order to investigate the absorption-properties of any uniaxial or biaxial crvstal, it is evident that sections must be obtained which are parallel to the 11 166 PHT8ICAL CHAKACTEKS OF MINERALS. 410 Beveral axes of elasticity. Suppose that f. 410 represents a rectangular solid with its sides parallel to tlie three axes of elasticity oi a biaxial crystal. In an orthorhonibic crystal the faces are those of the three diametral planes or pinacoids ; in a monoclinic crystal one side coincides with the clino* pinacoid, tlie others are to be determined for each species. The light transmitted by this solid is examined by means of a single Nic(jl prism. Suppose, first, that the light transmitted by the parallelopiped (f. 410) in the direction of the vertical axis is to be examined. When the shorter diagonal of the Nicol coincides with the direction of the axis b, the color observed belongfi to that ray vibrating parallel to this direction ; when it coincides with the axis a, the color for the ray with vibrations parallel. to a is observed. In the same way the Nicol sepai-ates the different ct)lored rays vibrating parallel to c and a respectively, when the light passes through in the direc tion of b. So also finally when the section is looked through in the dii-ection of the axis a, the colors for the rays vibrating parallel to b and c, respectively, are obtained. It is evident that the examination in tvvo of the directions named will give the three possible colors. For epidote, according to Klein, the colors for the thiee axial directions ^ —>-y y 4 k k ..... W\" -^ y' . [^ are : J Vibrations parallel to 6, brown (absorbed). " " a, yellow. Vibrations parallel to t, green. ' " a, yeUow. „ Vibrations parallel to t, green, " " i), brown (absorbed). The colors observed by the eye alone are the resultants of the double set ^A vibrations, in which the stronger color predominates ; thus, in the above example, the plane, normal to c is brown, to b, yellowish-gi-een, to a, green. In any other direction in the crystal, the apparent coloi- is tlie result of a mixture of those corresponding to tlie three directions of vibrations in differ- ent proportions. Dichroite is a striking example of the phenomenon of pleochroism. An instrument called a dichroscope has been contrived by Ilaidinger for examining this property of ci-ystals. An oblong rhombohedron of Ice- land spar' has a glass prism of 18° cemented to each extremity. It is placed 412 in a metallic cylindrical case, as in the figure, having a convex lens at one end, and a square hole at the other. On looking thi-ough it, the square hole appears double; one image belongs to the ordinary and the other to the extraordinary ray. When apleochroic crystal is examined witli it. by ';rana« mitted light, on revolving it, the two squares, at intervals of 90° in the revo DIAPHANEITY COLOR — LUSTRE. 167 Iiition, have different colors, corresponding to the direction of the vibrations of the ordinary and extraordinary ray in calcite. Since the two images aro situated side by side, a very slight difference of color is perceptible. Literature. — Pleochroism, Asterism, etc. Haidinger. Ueber den Pleochroismus der Krystalle ; Pogg. Ixv., 1, 1845. Ueber das Schillern der Kxystallfliichen ; Pogg. Ixx. , 574, 1847 ; Ixxi. , 321 ; Ixxvi., 99, 1849. lieusch. Ueber das Schillern gewisser Krystalle; Pogg. cxvi., 393, 1862; cxviii., 250. 1803 ; cxx. , 95, 18G3. V. Kobdl. Ueber Asterisraus; Ber. Ak. Miinchen, 1863, 65. HdUtihofer. Der Asterisraus des Calcites ; Ber. Ak. Miinchen, 1869. Vogelsang. Sur le Labradorite colore ; Arch. Neerland., iii., 32, 1868. Schrauf. Labradorit; Ber. Ak., Wien, Ix., 1869. Kosmann. Ueber das Schillern und den Dichroismus des Hypersthens ; Jahxb. Min., 1869, 368, 532; 1871, 501. Rose. Ueber den Asterismua der Krystallen ; Ber. Ak. Berlin, 1862, 614 ; 1869, 344 3. Lustre. The lustre of minerals varies with the nature of their surfaces. A varia- tion in the quantity of light reflected, produces different degrees of intensity of lustre ; a variation in the nature of the reliecting surface produces different kinds of lustre. A. The Jciiids of lustre recognized are as follows : 1. Metallie : the lustre of metals. Imperfect metallic lustre is expressed by the term i^uh-metalliti. 2. Adamantine: the lustre of the diamond. When also sub-metallic, it is termed rnetalliG-adamantine. Ex. cerussite, pyrargyrite, 3. Vitreous: the lustre of broken glas.3. An imperfectly vitreous lustre is termed suh-vitreous. The vitreous and sub-vitre(;us lustres are the most common in the mineral kingdom. Quartz possesses the former in an emi- nent degree ; calcite, often the latter. 4. Resinous: lustre of the yellow resins. Ex. opal, and some yellow varieties of sphalerite. 5. Pearly : like pearl. Ex. talc, brucite, stilbite, etc. When united with sub-metallic, as in hypersthenite, the term metallic-pearly is used. 6. Silky : like silk ; it is the result of a fibrous structure. Ex. fibrous calcite, fibrous gypsum. £. The degrees of intensity are denominated as follows: 1. Splendent : reflecting with brilliancy and giving well-defined images. Ex. hematite, cassiterite. 2. Shining : producing an image by reflection, but not one well defined. Ex. celestite, 3. Glistening : affording a general reflection from the surface, but no image. Ex. talc, chalcopyrite. 4. GUmmcriug : affording imperfect reflection, and apparently from points over the surface. Ex. flint, chalcedon3^ A mineral is said to be dull when there is a total absence of histre. Ex, dialk, the ochres, kaolin 168 PHYSICAL CHARACTERS OF MINERALB. Tlio true difference between metallic and vitreous lustre is dut to thft effect which the different surfaces have upon the reflected light ; in general, the lustre is produced by the union of two simultaneous impressions made upon the eye. If the light reflected from a metallic sui-face be examined by a Nicol prism (or the dichroscope of Haidinger), it will be found that both rays, that vibrating in the plane of incidence and that whose vibra- tions are normal to it, are alike, each having the color of the material, only differing a little in brilliancy ; on the contrary, of the light reflected by a vitreous substance, those rays whose vibrations are at right angles to the plane of incidence are more or less polarized, and are colorless, while those whose vibrations are in this plane, having penetrated somewhat into the medium and suffered some absorption, show the color of the substance itself. A plate of red glass thus examined will show a colorless and a red image. Adamantine lustre occupies a position between the others. The different degrees and kinds of lustre are often exhibited differently by unlike faxies oi the same crystal, but always similarly by like faces. The lateral faces of a right square prism may thus differ from a terminal, and in the right rectangnlar prism the lateral faces also may differ from one another. For example, the basal plane of apophyllite has a pearly lustre wanting in the prismatic planes. The surface of a cleavage plane in foliated minerals, very commonly differs in lustre from the sides, and in some cases the latter are vitreous, while the former is pearly. As shown by Haidinger, only the vitreous, adamantine, and metallic lustres belong to faces perfectly smooth and pure. In the first, the index of refrac- tion of the mineral is 1 '3 — 1 8 ; in the second, 1"9 — 2 5 ; in the third, about 2 o. The pearly lustre is a result of reflection from numberless lamellae or lines within a translucent mineral, as long since observed by Breithaupt. TV. HEAT. The expansion of crystallized minerals by heat depends, as directly as their optical properties, on the symmetry of their molecular structure as shown ill their crystalline form. The sajne three classes as before ai"e dis- tinguished : A. Immetric crystals, where the expansion is in all directions alike. B. IsodiametriG crystals, of the tetragonal and hexagonal systems. Ex- pansion vertically unlike that laterally, but in all lateral directions alike. O. Anisometi'ic, of the orthorhombic, monoclinic, and triclinic systems. Expansicm unlike in the three axial directions. The expansion by heat in the case of crystals may serve to alter the angles of the form, but it has been shown that the zone relations and the crystalline system remain con- stant. Mitscherlich found that in calcite there was a diminution of 8' 87' in the angle of the rhombohedron. on passing from 82^ to 212° F. , the form thus approaching that of a cube, as the temperature increased. Dolomite, in the same range of temperature, diminishes 4' 4tJ'; and in aragonite, between 68^ and 212° F. , the angle of the prism diminishes 2 46', and \-i : 1-? increases 5 30'; in gypsum, /: ^■- 1 is increased 5' 24", /: 1, 4 12\ and \-i : i-iia diminished 7' 24'. In some rhombohedrons. as of calcite, the vertical axis is lengthened (and the lateral shortened), while in others, like quartz, the reverse is true. The variation is Buch either way that the double refraction is diminished with the increase of heat ; foi calcite possesses negative double refraction, and quartz, positive. The conductive power of a crystal depends, as does expansi(>n, on the •ymmetry of its crystalline form ; this is also ti'ue of its power of trans- ELECTRICITY — MAGNETISM. 169 mitting or absorbing heat. It follows, moreover, from the analogous nature of heat and light, that heat rays are polarized by reflection; and by transmission in anisotrope media, in the same way as the rays of light. These subjects, considei-ed S(jlely in their relation to Mineralogy, are of minor importance; they belong to works on Physics, and reference may be made to those whose titles are given in the Introduction, as also to the works of Schrauf and Groth. The change in the optical properties of crystals produced bj heat ha.s already been noticed (p. 151). y. ELECTRICITY— MAGNETISM. The electi-ic and magnetic characters of crystals, as their relations to heat, bear but slightly upon the science of mineralogy, although of high interest to the student of physics. Friotional electricity. — Tlie development of electricity hy friction is a familiar fact. All minerals become electric by friction, although the degree to which this is manifested depends upon their conducting or non- conducting power. There is no line of distinction among minerals, divid- ing them into positively electric and negatively electric ; for both kinds of electricity may be presented b}' different varieties of the same species, and by the same variety in different states. The gems are positively electric only when polished ; the diamond alone among them exhibits positive elec- tricity whctiier polished or not. The time of retaining electric excitement is widely different in different species, and topaz is remarkable for continu- ing excited many hours. Pressure also develops electricity in many minerals ; calcite and topaz are exam])les. Pyro-electricity. — A decided change of temperature, through heat or cold, develops electricity in a large number of minerals, which are hence c2i\\Qdi pyro-electric. This property is most decided, and was first observed in a series of minerals which are hemimorphic or hemihedral in their development. The electricity in these minerals is of opposite character in the parts dissimilarly modified. Thus in tou]-maline and calamine, the crystals of which are often differently modified at the two exti'emities, posi- tive and negative electi-icity are developed at these extremities or poles respectively. When the extremity becomes positive on heating it has been called the analogue pole, and when it becomes negative, it has been called the antilogue. The names were given by Rose and Riess, who investigated these phenomena. For a change of temperature in the opposite direction, that is, cooling, the reverse electi-ical effect is observed. Boracite, on whose crystals the + and — tetrahedrons often occur, shows by heating the positive electricity for the faces of one tetrahedron and the negative for those of the other. Further investigations by Ilankel and others (see Literature) have ex- tended the subject and shown that the phenomena of pyro-electricity belong to the (;rystals of a large number of species. Moreover, it is not, as once supposed, essentially connected with hemihedral development. Tlie num- ber of poles, too, may be more than two, that is, the points at which poai 170 PHYSICAL CHARACTERS OF MINERALS. tive and negative electricity is developed. Thus for prehnite tliere Is a large series of such poles, distril)uted over the surface of a crystal. The hivestigatious of Ilaukel have shown in general, that in crystals not hemi- hedi-ally developed, tlie same electricity is developed at both extremities of the same axis, and the distinction between j)ositive and negative electricity is only shown by reference to the different crystallograpliic axes; on sym- metrically formed crystals of the isodiametric class the electricity is the same in all lateral directions, that is, on all prismatic planes, while different at the extremities of the vertical axis. Thei'Tno-electricit/y. — When two different metals ai-e bi-onght into con- tact, a sti-eam of electricity passes fi-om one to the other. If one is lieated the effect is more decided and is sufficient to detiect more or less vigoionsly the needle of a galvanometer. According to the direction of the cni-i-ent produced by the different metallic substances, the}^ are arranged in a thermo-electrical series; the extremes are occupied by antimony ( + ) and bismuth (— ), the electrical stream j^assing from bismuth to antimony. This subject is so far important for mineralogy, as it was shown by Bunsen that the natural metallic sulphides stand further off in the seiies than antimony and bismuth, and consequently by them a stronger stream is produced. The thermo-electrical relations of a large number of minei'als was determined by Flight (Ann. Ch. Pharm., cxxxvi.). It was early observed that some minerals have varieties which are both -f and — . This fact was made use of by Rose to show a relation between the plus and minus hemihedral varieties of pyrite and cobaltite. The later investigations of Schrauf and Dana have shown, however, that the same peculiarity belongs also to glaucodot, tetradymite, skutterudite, danaite, and other minerals, and it is demonstrated by them that it cannot be dependent upon crystalline form, but, on the contrary, upon chemical composition. Magnetism. — The magnetic properties of crystals are theoretically of interest, since they, too, like the optical and thernjic, are directly dependent upon the foi-m ; hence, with relation to magnetism they group themselves iuto the same three classes before referred to. All substances are divided into two classes, the jparamagnetiG and dia- inagnetic, according as they are attracted or repelled by the poles of a mag net. For purposes of experiment the substance in question, in the form of a rod, is suspended between the poles of the magnet, being movable on a horizontal axis. If of the first class, it will take a position jyarallel^ and if of the second class, transverse^ to the magnetic axis. By the use of a sphere it is possible to determine the relative amount of magnetic induction in different directions of the same substance. Experi- ment has shown that in isometric crystals the magnetism is alike in all dii'ections ; in those optically uniaxial, that there is a direction of maximum and, normal to it, one of minimum magnetism ; in biaxial crystals, that there are three unequal axes of magnetism, the position of which may be deteruiined. A few minerals have the power of exerting a sensible influence upon the magnetic needle, and are hence said to be magnetic. This is true of mag- netite and j)yrrhotite (magnetic pyrites) in particular, also of franklinite, almandite, and other minerals, containing considerable iron protoxide (FeO). When such minerals in one part attract and in another repel the poles oi TASTE AND ODOB. 171 the n)agiiet, they are said to -possess polar iti/. This is true of the variety of magnetite called in popular language loadstone. Literature.— Electkicity.* Hankd. Ueber die Thermo-Electricitat der Krystalle; Pogg., xlix., 493 ; L, 237, 1840; Ixi., 281. Rose u. Hies. Ueber die Pyro-Electricitiit der Mineralien ; Ber. Ak. Berlin, 1843. Ueber den Zusammeuhang zwischen der Form und der elektrischen Polaiitat de* Krystalle ; Ber. Ak. Berlin, 183G. V. Kvbell. Ueber Mineral-Electricitat ; Pogg., cxviii., 594, 1863. Bunseu. Thermo-Ketten von grosser Wirksamkeit ; Pogg., cxxiii., 505, 1864. Fviedel. Sur les proprieti-s pyro-electrique des Cristaux bons conducteurs de 1' electricity Ann. Ch. Pbys., IV., xvii., 79, 1869. Rose. Ueber den Zusammenhang zwischen hemiedrischer Krystallfonn und thermo-elek trischeui Verhalten beim Eiseukies und Kobaltglanz ; Pogg., cxHi., 1, 1871. Sc/iruufu. E. S. Dana. Ueber die th>rmo-elektrischen Eigenschaften von Mineral varie tiiten; Ber. Ak. Wien, Ixix., 1874 (Am. J. Sci., III., viii., 255). Rdiikel. Ueber die thermo-elektrischen Eigenschaften des Boracites ; Sachs. Ges. Wiss. vi., 151, 1865; ibid., viii., 323, 1866; Topaz, ix., 1870, 359; 10 Abhandlung, 1872, 21; cal cite, beryl, etc., 1876. On MAGNETISM reference maybe made to Faraday (Experimental Researches) ; Tyndall Phil. Mag. ; Knoblauch and Tj'ndall, Pogg., Ixxxi., 481, 498 ; Ixxxiii., 384 ; Pliiicker, Pogg., lxxii.,315; lxxvi.,576; lxxvii.,447; Ixxxvi., 1; Grailich u. von Lang, Ber. Ak., Wien, zxxii., 43 ; xxxiii., 439, etc., eta VI. TASTE AND ODOR. In their action upon the senses a few minerals possess taste, and others under some circumstances give off odor. T.sstp: belongs only to soluble minerals. The different kinds of taste adopted for reference are as follows : 1. Astringent / the taste of vitriol. 2. Sweetish astringent ; taste of alum. 3. Sdline ; taste of common salt. 4. Alkaline y taste of soda. 5. Cooling ; taste of saltpeter. 6. Bitter ; taste of ej)Som salts. 7. Sour : taste of sulphnric acid. Odor. — Excepting a few gaseous and soluble species, minerals in the dry - unchanged state do not give off odor. By friction, moistening with the breath, and the elimination of some volatile ingredient by heat or acids, odors are sometimes obtained which are thus designated : 1. Alliaceous ,' the odor of garlic. Friction of arsenical iron elicits this odor; it may also be obtained from arsenical compounds, by means of heat, 2. Horse-radish odor ^ the odor of decaying horse-radish. This odor is strojigly perceived when the ores of selenium are heated, 3. Sulphureous ,' friction elicits this odor from pyrite and heat from many sulpliides, 4. Bituminous ^ the odor of bitumen, 5. Fetid ^ the odor of sulphuretted hydrogen or rotten eggs. It is eli- cited by friction from some varieties of quartz and limestone, 6. Argillaceous / the odor of moistened clay. It is obtained from ser- * See also on p. 190. 172 PHYSICAL CHARACTEK8 OF MINEEALS. pentine and some allied minerals, after moistening them with thti breath ; othei-s, as pyrargillite, afford it when heated. The Feel is a character which is occasionally of some importance ; it ia said to be smooth (sepiolite), greasy (talc), harsh, or meagre, etc. Some miiiei-als, in consequence of their hygroscopic character, adhere to the tongue^ wlieE brought in contact with it. SECTION II.— SUPPLEMENTAKY CHAPTER. I. COHESION AND ELASTICITY (pp. 119 tO 123). The etching-figures {Aetzfiguren) produced by the action of appropriate solvents upon the surfaces of crystals have been further investigated in the case of a considerable number of minerals, and the results have in some cases served to throw light upon the question as to which crystalline system a given species belongs. See the investigations of Baumhauer of the etching-figures of lepidolite, tourmaline, topaz, calamine, Jahrb. Min., 1876, i. ; pvromorphite, mimetite, vanadinite, ib., 1876, 411 ; of adularia, albite, fluori'te. ib., 1876, 602 ; of leucite, Z. Krvst, i.,257, 1877; quartz, ib., ii., 117, 1878 ; mica (zinnwaldite), ib., iii., 113, 1878; boracite, ib., iii., 337, 1879 ; perofskite, ib., iv., 187, 1879 ; nephelite, ib., vi., 209, 1882. (For earlier papers giving results of etching experiments on muscovite, garnet, linnaeitc, biotite, epidote, apatite, gypsum, in Ber. Ak. Miinchen, 1874, 245 ; 1876, 99.) On the etching-figures of alum, see Fr. Klocke, Z. Kryst., ii., 126, 1878 ; of the different micas, F. J. WiiK, Oefv. Finsk. Vet. Soc., xxii., 1880. On the artificial twins (twinning-plane —^R) of calcite produced by simple pressure with a knife-blade on the obtuse edge of a cleavage frag- ment, see Baumhauer, Zeitschr. Kryst., iii., 588, 1879 ; Brezina, ib., ivi, 518, 1S80. Tlie fragment should have a prismatic form, say 6-8 ram. in length and 3-6 mm. in breadth, and be placed with the obtuse edge on a firm horizontal support. The blade of an ordinary table-knife is then applied to the other obtuse edge, as at a (f. 412a), and pressed gradually and firmly down. The result is that the portion of the crys- tal lying between a and h is reversed in position, as if twinned parallel to the horizontal plane —\R. The twinning surface, gee, is perfectly smooth, and the re-entrant angle corresponds very exactly with that required by theory (Brezina). Earlier observations by Pfaff and Keusch haA'C shown that twin lamellas {—\R) may be produced in a cleavage mass of calcite of prismatic form, by simple pressure exerted perpendicular to a straight ter- minal plane. Such twinning lamellae are often observed in thin sections of a crystalline limestone when examined in polarized light under the micro- scope. On the application of the fracture-figures (Schlagfiguren) in the optical examination of the mica species see Bauer, ZS. G. Ges.. xxvi., 137, 1874 (for earlier papers see p. 122) ; Tschermak, Z. Kryst., ii., 14, 1877. On the occurrence of Gleifflachen on galena sec Bauer, Jahrb. Min., 1882, i., 183. II. SPECIFIC GRAVITY (pp. 123, 124). Use of a Solution of high Specific Gravity. — A solution of merciwic iodide in potassium iodide (Hgol in KI) affords a means of readily ob- taining the specific gravity of any mineral not acted upon by it chemically, 173 174 SPECIFIC GRAVITY. and for which G. < 3-1 ; and also of separating from each other minerals of different densities, when intimately mixed in the form of small fragments. The solntion is called the iSonstadt solution, having been first proposed by E. SoNSTADT in 1873 (Chem. News, xxix., 127) ; its application for the above objects was proposed by Church in 1877 (Min. Mag., i., 237) ; and the method elaborated by TiioULET in 1878 (C. R., Feb. 18, 1878 ; Bull. Soc. Min., ii., 17, 189, 1879), and later by Goldschmidt (J. Min., Beil.- Bd.,i., 179, 1881). The solution is prepared (Goldschmidt) as follows : The KI and HgJ are taken in the ratio of 1:1-230, and introduced into a volume of Avater slightly greater than is required to dissolve them (say 80 cc. to 5U0 gr. of the salts) ; the solution is then filtered in the usual way and afterward evap- orated down in a porcelain vessel, over a water-bath, until a crystalline scum begins to form, or when a fragment of tourmaline (G. =3-1) floats ; on cooling, the solution has its maximum density. If the mercuric iodide is not quite pure a small quantity in excess of that required by the above ratio must be taken. The highest specific gravity for the solution obtained by Gold- schmidt was 3-196, a solution in which fluorite floats. This maximum is not quite constant, varying with the moisture of the atmosphere and with the temperature. The method of using the solution for obtaining the specific gravity of small fragments of any mineral is, according to Goldschmidt, as follows : The fragments are introduced into a tall beaker, say 40 cc. capacity, with a por- tion of the concentrated solution ; then water is added drop by drop (or ;', dilute solution of the same for high densities) from a burette, until the frag- ments, after being agitated, are just suspended, and remain so Avithout either rising or falling. This process requires care and precision, since the princi- pal error to which the method is liable is involved here. The solution is now introduced into a little glass flask, graduated say to hold just 25 cc, and this amount having been exactly measured off, the weight is taken ; then the solution is poured back into the original beaker and the fact noted whether the fragments still remain suspended ; then introduced again into the flask and weighed, and so a third time. The average result of the three weigh- ings, diminished by the known Aveight of the flask and divided by 25, gives the specific gravity. The exact measurement of the 25 cc. is a matter of importance, and is most easily accomplished by adding at first a little more than enough and then removing the excess by a capillary tube or a piece of filter paper ; the reading is best taken from the loAver edge of the meniscus. It is not necessary to clean and dry the flask each time. The Aveighing need not be very accurate, as an error of 25 mgr. only involves a change of a unit in the third decimal place (-001). The describer readily obtained results accurate to three decimals. The adA^antages of the method are that it is readily applicable in the case of small fragments (dust is to be avoided), it is easily used, and any want of homogeneity in the mineral makes itself at once apparent. This solution is also most useful in afPording a means of separating me- chanically different minerals when intimately mixed together ; as, for example, in a fine-grained rock. For this purpose the rock must first be pulverized in a steel mortar, then put through a sieve, or better, through several, so as to obtain a series of sets of fragments of different size ; the dust is rejected. The fragments should be examined under the microscope, to see that they are homogeneous ; the largest fragments satisfying this condition will give the best results. SPECIFIC GRAVITY 175 According to Thoiilet the best method of procedure is to first determine the density of the fragments approximately by inserting typical ones in a series of samples of the solution of gradually uicreasing density. This point deter- mined, some 60 cc. of the concentrated solution are introduced into the tube, A, and 1 or 2 grams of the weighed fragments (T'"'^'^ added. Then the tightly-fitting rubber cork with the tube, F, is inserted ; the tube, F, is connected by a rubber tube with an air pumjD, and the air bubbles arc in this way removed from the powder. The heavy parts of the mixture fall to the bottom, and are removed by opening the stop-cock at C, and are washed out by use of the tube, B ; the otlier fragments float. Now a quantity of distilled water is added in order so to dilute the solu- tion as to cause the next heavier portions to sink, as determined by the equation v(D A) A — 1 where v = volume of the solution, D its specific gravity, Vi the volume of the water, and A the density desired. The cock at D is shut and that at C opened and air blown through the side tube, so as to mix the solution thoroughly ; then the original operation is repeated, and so on. GoLDSCHMiDT recommouds the following method of procedure. The separation is conducted in a small slender beaker of about 40-50 cc. capacity. Instead of the series of standard solutions (the density of which is liable to alter) a series of minerals of known specific gravity are used as indicators ; by means of them it is easy to determine the limits as to density which are required to make the separation desired, the constituent minerals having been determined by the microscope. For example, suppose it to be desired to separate augite, horn- blende, oligoclase, and orthoclase ; labradorite and albite are taken as indica- tors. Augite falls at once in the concentrated solution ; if diluted till the lab- radorite sinks, all the hornblende ^oes down ; before or with the albite the oligoclase sinks, and the orthoclase is left suspended. By the use of the 25 cc. flask, the exact specific gravity in each ease can be obtained if desired. The operation of separation goes oii as follows : The rock powder and the indicators are inserted with say 30 cc. of the concentrated solution into the beaker spoken of, then the whole is stirred vigorously and allowed to settle, and the lighter part decanted off. The heavier part which has settled is removed with a jet from a wash bottle, without disturbing the lighter fragments adhering to the upper part of the beaker. The latter are subsequently removed, washed, dried, again washed in the solution, and added to the rest for the further separation. If the separations accomplished in this way are not complete, they may be repeated most conveniently with the Thoulet apparatus. Under favorable conditions, and if the manipulation is skilful, the separation can be accom- plished with considerable exactness. For the best results the process must be repeated several times. Thoulet recommends also (I. c.) this method of determining the specific gravity of small fragments of minerals. A float of wax (inclosing any suit- able solid body) is made with a specific gravity of from 1 to 2. The frag- 17G SPECIFIC GRAVITY. ments of the mineral are lightly pressed into the wax float, and tliis intro- duced into the Sonstadt solution, of such strength that the float remains in equilibrium at any level. If P, V, D are respectively the weight, volume, and density of the float alone ( ^~ 77 ) and^, v, d the same values for the fragments alone \v ~ L^\ and finally a the density of the liquid in which the loaded float is in equilibrium ; then ^^?-±J or J^__iLA__ d Breon has proposed (Bull. Soc. Min., iii., 40, 1880) the following method for separating different minerals intimately mixed, which is applicable in cases where their density is greater than that of the Sonstadt solution. Lead chloride and zinc chloride, in appropriate proportions, are fused together (at 400°_C.) and by this means a transparent or translucent solution is obtained of higb specific gravity. Briefly, the method of procedure is as follows : A conical tube of glass is taken, of about 12 to 15 cc. capacity ; this will allow of the treatment of 4 or 5 grams of the njixed minerals. The clilorides of lead and zinc, in approximately the proper proportions, are placed in the glass tube and this, surrounded by sand, inserted in a platinum crucible. On the ap- plication of heat the zinc chloride fuses first, but finally a homogeneous mix- ture of the two liquids is obtained. Now, little by little, the mineral frag- ments are introduced and the liquid stirred ; then on allowing it to stand for a moment the iieavier particles sink to the bottom and the lighter ones float. The tu!)e is now removed from its sand bath and cooled rapidly. When solidified but still hot the glass may be plunged into cold water, in which case it will be broken and the fragments can be removed, so that the fused mass within can be obtained free. Subsequently the fragments in the upper and lower parts of the mass can be separated by solution in water to which a little acetic acid has been added. The author has operated on minerals vary- ■ ing from wolframite (G. = 7-o) to ber\d (G. = 2-7), and in some samples of sand has separated as many as 12 constituent minerals. D. KLEiJf (Bull. Soc. Min., iv., 149, 1881) has proposed to use one of the boro-tungstate salts in the place of the Sonstadt solution for the separation of minerals whose specific gravity is as high as 3-0. The most suitable salt fortius purpose is the cadmium compound, H4Cd!;B2W:X)34-|-lG aq. It dis- solves at 22° C. in about ^^ its weignt of water, and crystallizes out both on eva]")oration and cooling. At 75° "C. it melts (best over a water-bath) in its water of crystallization to a yellow liqnid, on the surface of which a spinel crystal (G. =3-55) floats. By the ap])lication of the Thoulet appara- tus (see above), so arranged as to allow of the application of heat, solutions of any specific gravity, hot or cold, from 1 to 3-6, can be obtained. A num- ber of common minerals (e. g. chrysolite, cpidote, vesuvianite, some varie- ties of amphibole and mica) can be separated by the use of this liquid, while the Sonstadt solution is inapplicable. The fragments under examination must be free from the carbonates of calcium or magnesium, which decom- pose the boro-tungstate of cadmium. TOTAL REFLECTKOMETER. 177 III. LIGHT (pp. 125-1G8). Measurement of Indices of Eefraction. For the determination of the indices of refraction of crystallized minerals^ various imi)i'ovemeuts have been made in former methods and some new methods devised. Use of ill e Horizontal Goniometer, — The ordinary method for determining the index of refraction, requiriug tlie observation of the angle of minimum deviation (rf) of a light-ray on passing through a prism of the given mate- rial, having a known angle {a), and with its edge cut in the proper direc- tion, has already been mentioned (p. 128). The two measurements required in this case can be readily made with the horizontal goniometer of Fuess, described on p. 115. In this instrument the collimator is stationary, being fastened to a leg of the tripod support, but the observing telescope with the verniers moves freely. In the use for this object the graduated circle is to be clamped, and the screw attachments connected with the axis carrying the support, and the vernier circle and observing telescope are to be loosened. The method of observation requires no further explanation (see also pp. 141, 150). Total Bcflccfrometcr. — F. KoHLRAUScnhai shown (Wied. Ann., iv,, 1,1878) that the principle of total reflection (p. 128) may be made use of to deter- mine the index of refraction in cases where other methods are inapplicable. l^o prism is required, but only a small fragment having a single polished surface ; this may be cut in any direction for an isoti-ope medium ; it should be parallel to the vertical axis in a uniaxial crystal, and perpendicular to the acute bisectrix with a biaxial crystal. The arrangements required are, in their simplest form, a wide-monthed bottle filled with carbon disulphide (refractive index l-(5) ; the top of this is formed by a fixed graduated circle, and a vertical rod, with a vernier attached, passes through the plate and car- ries the crystal section on its extremity, immersed in the liquid. The angle through which the crystal surface lying in the axis is turned is thus meas- ured in the same way as in f. 412h, by the vernier on the stationary gradu- ated circle. The front of the bottle is made of a piece of plate glass, and through this passes the horizontal observing:: telescope, arranged for parallel light. The rest of the surface of the bottle is covered with tissue-paper, through wdiich the diffuse illumination from say a sodium flame has access ; the rear of the bottle is suitably darkened. When now the observer looks through the telescope, at the same time turning the axis carrying the crystal section, he will finally see, if the source of illumination is in a proper oblique direction, a sharp line marking the limit of the total reflection. The angle is then measured off on the graduated circle, when this line coincides with one of the spider lines of the telesQppe. Xow the crystal is turned in the opposite direction, and the angle again read off. Half the observed angle {'Za) is the angle of total reflection ; if n is the refractive index of the car- bon disulphide, then the required refractive index is equal to n sin a. Under favorable conditions the results are accurate to four decimal places. This method is limited, of course, to substances whose refractive index is less than that of the liquid medium with which the bottle is filled. With a sec- 12 178 MEASUREMENT OF INDICES OF KEFRACTION. tion of a uniaxial crystal, whose surface is must conveniently parallel to the vertical axis, the method is essentially the same. The section is so placed that in it the direction normal to the optic axis is horizontal. The light will be here separated into two rays, having separate limiting surfaces, and with a Nicol prism it is easy to determine which of them corresponds to the vibrations i^arallel and perpendicular, respectively, to the optic axis. For biaxial crystals the surface should be normal to the acute bisectrix. This will give by a.;tual observation the values of a and y, and if IE, the appa- rent axial angle in air, is known, then p, the mean index can be calculated (see p. 150). Instead of carbon disulphide the Sonstadt solution, with n = 1.73, can be employed. The total refiectrometer of Kohlrausch has been adapted in practical form to the horizontal goniometer (f. 372a) of Fuess (see Liebisch, 13er. Ges. Nat. Fr. Berlin, Dec. 16, 1879). Klein has sug- gested some improvements (J. Min., 18^9, 880), and Bauer (J. Min., 188*-^, i., 132) has shown how the method can be simply applied to the instrument for tbe measurement of the optic axial angle (f. 412h), and without its modification in any important respect. Qx'ixcKE (abstract in Z. Kryst., iv., 540) has described another method for obtaining the refractive index of a substance on the principle of total reflection. In a word, it consists in observing on a spectrometer the limit- ing angle of total reflection for a plane section of the substance to be inves- tigated, brought with oil of cassia between two flint glass prisms. SoEBY (Proc. Roy. Soc.,' xxvi., 384; Min. Mag., i., 97, 194; ii., 1, 108) has developed the method of obtaining the refractive index of a transparent medium, first described by Duke de Chaulnes (1767), and has shown that under suitable conditions it allows of determinations being made with con- siderable accuracy. This method consists in observing the distance {d) which the focal distance of the objective is changed when a plane-plane plate of known thickness (t) is introduced perpendicular to the axis of the microscope between the objective and the focal point — here ^' ~ t—d Sorby makes use of a glass micrometer, upon which two systems of lines perpendicular to each other are ruled. The micrometer screw at g, in the Rosenbusch microscope (f. 412k, p. 181), makes it possible to measure the distance through which the tube is to be raised and lowered down to -001 mm. ; consequently both t and d can be obtained with a high degree of accuracy. Bauer has shown that tlie indices of refraction may be obtained with con- siderable accuracy from measurements, in the plane of the axes, of the distances between the Ijlack rings in the interference figures as seen in homogeneous light. The relation between these distances and the optical axes of elasticity was established by Neumann (Pogg. Ann., xxxiii., 257, 1834). Bauer has made use of this method in the case of muscovite (Ber. Ak. Berlin, 1877, 704). He has also developed the same method as applied to uniaxial crystals and employed it in the case of brucite (ib., 1881, 958). Polarization Instruments. Polariscope. — The earlier forms of polariscope for converging and for par- POLAKIZATION INSTRUMENTS — POLAKISCOPE. 179 412c. 412e. allel licrlit, as arranfred hx Groth and constructed by Fuess, are sliown in figs. 384, 385, p. ]34. ^The'more recently constructed instru- ments (see Liebisch, ]. c, p. 342 et scq.), ■vvitli some impor- tant improvements, are sbown in f. 412c and f. 41 2d. The lower tube, /, containing the analyzer, has about it a collar, /' (see details, figure 412f), with a triangular projection on the upper edge ; this fits into one of two correspond- ing triangular depressions {0° and 45^) in the surround- ing tube, g. This serves to fix the position of the tube, that is, of the vibration-plane of the enclosed Xicol, with ref- erence to the fixed arm, B, to which tlie verniers arc at- tached, so that the principal section of the Nicol either co- incides with, or makes an angle of 45^ with the 0^ lino of the verniers. The circle, i, is graduated to 1°, and with the vernier gives readings to 2' ; the section to bo examined is supported at k. A similar collar, u, surrounds the upper tube, V, by which the posi- tion of the micrometer (at r) (this micrometer consists of two lines at right angles, one of which is graduated) can also be fixed relatively to the ver- nier so that the graduated line of the micrometer is perpendic- ular to the plane through the axis of the instrument and the zero of the vernier. The tube above carrying the Xicol has at s a graduated circle which shows the relative directions of the vibration-planes of the two Nicols, The lenses at n ando 412F. are arranged so that they may be used all together, when strongly converging- light is needed, or the small lenses may be removed, so that three combina- tions are possible. A small screw at a makes it possible to adjust the position of the glass micrometer so that it shall always be in the focus of the lenses at 0, a point which varies according to the combination of lenses employed. 180 POLARIZATION INSTRUMENTS. 412g. S((iuroscope — Calderon^s Plate. — The ftauroscope is essentially the same in- strument as that mentioned in f. 385. Instead, however, of employing the Brezina interference-plate of caleite, a double plate is used, as suggested by Cal- deron (Z. Kryst., ii., 08). This plate is, in fact, an artificial twin, and is made as follows : A caleite rhoinbohedron is cut through along the shorter diagonal ; from each half a wedge-shaped portion is cut away and the two surfaces thus produced, after being polished, are cemented togethei-. A plane-plane plate is then cut from this (comjxire figure) by grinding away the angles as indicated; this plate is divided into two halves by the lino of separation of the artificial twin. Such a i)late is very sensitive, and allows of very exact observations. It is placed at m (f. 412d), and when the arrangements are completed \.--'"' ~'^'~-~i the dividing line of the caleite exactly coincides with a vibration-plane of one of the two Nicols. A diaphragm is placed above with holes of varying size according to the minuteness of the crystal to be examined. The stauroscopic determinations made by Calderon showed an error of only 3' to 7'. Axial-augle Instrument (see p. 148). — The instrument for the measure- ment of the angle of the optic axes is in principle essentially that of Des Cloizeaux, but in the details of the construction various improvements have 412II. been introduced (see f. 412h). The same arrangement of adjustable collars at u' and/' is employed as in the other instruments, to fix the position of the principal sections of the Nicols relatively to the plane passing through the axis of the observing telescope and the axis'of rotation. Instead of the straight rod in 1 401, in the pincers at the extremity of which the crystal section is POLARIZATION MICROSCOPE. 181 182 POLARIZATION INSTRUMENTS. held, there is licre an arrangement consisting: of two concentric tiihes, turn- ing indepciulently, but so as to be clamped at c. The adjustable disk hav- ing a horizontal motion at F, and the splierical segment at II (Petzval eupiiort) allow of the section being both centered and adjusted. Pohiriscope of Adams-Schneider. — A polariscope of peculiar construction, giving a very large held of view, and at the same time allowing of the meas- urement of the axial angle, was proposed in 1875 by Adams (Phil. Mag.. IV., l.,p. 13, 1875; v., viii., 275). The same instrnnient has been further devel- oped by Schneider (Carl. Rep., xv., 744), and is also described by Becke (Min. Petr. Mitth., ii., 430, 1879). The peculiarity of the instrument con- sists in this, that the middle plano-convex lenses which ordinarily are fixed, to the upper and lower lens systems, respectively (see o, o, o, and ii, n, n, in f. 412c), are here separated from the others in a common support, and to- gether form a sphere. The course of the light-rays will be always the same, hoAvever the sphere is rotated about its fixed centre. Between the semi- spherical lenses a space is left, and here is introduced the section to be ex- amined, which, turning with the surrounding lenses, can obviously be made to take any desired position with reference to the axis of the instrument. An aj^propriate arrangement makes it possible to measure the angle through Avhich the section must be rotated to bring first one and then the second optic axis in coincidence with the axis of the instrument. The advantages of the instrument consist in the fact that the field of view is very large, and at the same time it allows of iilacing the section in any desired position rela- tively to the axis. Moreover, the angle measured is the apparent angle for the glass of which the lenses are made, so that the axes are visible in cases where this would not he the case, because of total reflection, cither in air or in oil, Polarization-Microscope. — The investigation of the form and optical prop- erties of minerals when in microscopic form, as they occur, for example, in rocks of fine crystalline structure, has been much facilitated by the use of instruments specially adapted for this purpose. The most serviceable polarizing microscope, for general use, is that described by Rosenbusch ( Jahrb. Min., 187G, 504), and made by E. Fuess, of Berlin. A sectional view is given in f. 412k. The essential arrangements are as follows : The coarse ad- justment of the tube carrying the eye-piece and objective is accomi)lished by the hand, the tube sliding freely in the support, p. The fine ad- justment is made by the screw, g ; the screw-head is graduated, and turns about a fixed index attached to p, by this means the distance through Avhich the tube is raised or lowered can be measured to 0*001 mm.; this is important in determin- ing the indices of refraction by the De Chaulnes-Sorby meth- o(i (see p. 178). The polarizing prism (Razumovsky) is placed below the stage at" r, in a sup- port, with a graduated circle, so that the position of its vibnifon-plane can be fixed. The analyzing prism is placed above the eye-piece in a support, s, which may be removed at POLARIZATION MICEOSCOrE. 183 pleasure ; the ed^e of tins is graduated and a fixed mark on the plate, /, makes it possible to set the vibration-plane in any desired position. AVhen both prisms are set at the zero mark, their vibration-planes are crossed (±); when either is turned 00°, the planes are parallel (||). Tbe stage is made to rotate about the vertical axis, but otherwise is fixed ; its edge is graduated, so that the angle through whicli it is turned can be measured to 4°. Three adjustment screws, of wiiich one is shown at n, n, make it possible to bring the axis of the object glass in coincidence with axis of rotation of the stage (see fur- ther the detailed drawing at the side). This instrument is especially applicable to the study of the form and opti- cal properties of minerals as they are found in thin sections of rocks (on the method of preparing see p. 159), although it can also be used with small in- dependent crystals and crystalline sections or fragments. The more impor- tant points to which the attention is to be directed, more particularly in the case of minerals in sections of rocks, arc : (1) crystalline form, as shown in the outline ; (2) direction of cleavage linc3 ; (3) index of refraction; (4) light absorption in different directions, i. c., dichroism or pleochroism ; (5) the isotrope or anisotrope character, and if the latter, the direction of the planes of light-vibration — this will generally decide the question as to the crystalline system ; (G) position of the axial plane and nature of the axial interference figures when they can be observed, and the positive or negative character of the double refraction ; (7) inclosures, solid, liquid or gacoous. In regard to these several points a few general remarks may be made.* (1) CrysfaUine Form. — In most rocks well defined crystals are rather the exception ttian the rule. It will be consequently only in occasional sections (e. g. more commonly in vol- canic rocks) that a clear crystalline outline is observed. The form of this outline will de- pend upon the direction in which the section is cut, and will vary as it varies ; this fact will explain why in a given rock section so many widely different forms of a given mineral are observed ; this irregularity is increased by the fact that the crystals may be more or less distorted. For the recognition of the form, consequently, considerable familiarity with the various outlines likely to occur in the case of a given species is very desirable. The angles between any two crystalline directions is obtained by first bringing one of them in coincidence with a spider line in the eye-piece, the adjustment at N having been previously made, and then noting the angle through which the crystal, i. e.. the stage, must be rotated to bring the other direction in coincidence with the same spider line. (2) Clenvnqe. — The process of grinding involved in the making of a thin section tends to develop (he cleavage lines. Here arc to be noted, (1) the direction of cleavage (measured as above), depending on the direction in which the section is cut ; and (2) the character of the cleavage. For example, a basal section of a crystal of amphibole shows the cleavage lines parallel to the pi-ism (124-^°); a vertical section shows one set of vertical and parallel * For the full development of this subject, see the works of Rosenbusch and Zirkel (titles on p. 111.) ; also the following : BoRicKY, E. Elemente einer neueu chemisch-mikroskopisehen Mineral- und Gesteins- analyse, 72 pp. 4to, Prag, 1877. CoHEX, E. Sammlung von Mikrophotographieen zur Veranschaulichung der mikroskop- ishen Structur von Mineralien und Gesteinen, aufgenommen von J. Grimm in OiTenburg, 1, 2, 3, 4, 5 Lfg., Stuttgart, 1881-82. DoELTER. Die Bestimmung der petrographisch wichtigeren Mineralien durch dasMikro- skop ; Eine Anleitung zur mikroskop. Gesteins-Analyse, ijG pp. 8vo, Vienna, 1876. FouQUE, F. and Mjchel-Lkvv, A. Mintralogie niicrographique, roehes eruptives Fran- gaises, 509 pp. 4to, Paris, 1879. RuTLEY, F. The Study of Rocks, 319 pp. 12mo, London, 1879. Thoulet. Contributions a IV' tude des proprietes physiques et chemiques des mineraux microscopiques, 77 pp. 8vo, Paris. Hawes, G. W. The Mineralogy and Lithology of New Hampshire (Geology of New Hampshire, vol. iii.), 262 pp. 4to, with 12 plates. Pages 8-18 of this work give an excel- lent summary of microscopic methods of investigation," as applied to rocks and minerals. 184 POLAKIZATION INSTKUMENTS. cleavage lines. On the other hand, a basal section of a crystal of pyroxene shows the pris- matic cleava^re, here less perfect than in the ampliibole, and at an angle of 87° and 93° ; a vertical section again shows only one set. Also a basal section of mica shows no cleav- age lines, but a vertical section shows a series of very fine parallel lines corresponding to the highly perfect basal cleavage. (3) The index of refraction is obtained by the method of the Duke de Chaulnes, as devel- oped by Sorby (see p. 178). (4) Pleochroism. — To examine the pleochroism of a mineral section, the lower prism is inserted and set at 0°, so that its vibration-plane coincides with the direction (I to IbO" on the stage. If now the section be placed on the stage and the latter rotated, the absorption of the light vibrating in the same plane with the prism can be observed. For example, a vertical section of biotite is dark when the direction of the cleavage lines is || with the above named line (0° to 180° of stagey for the light which it transmits has vibrations in this plane only, and these are strongly absorbed ; on the contrary, when the stage is rotated 90° the section becomes light, because the light vibrating || to this direction, is but slightly ab- sorbed ; on the other hand, a basal section shows no diifereiice of light absorjition. (5) Isotrope or Anisoirope, etc. — Supposing the prisms in position and pkced with their vi- bration-planes perpendicular, a section of an amorphous substance, as gla.7, 1879, and Lehrb. Min., p. 89 et seq., 1881). The explanation of the optical phenomena referred to above, which was presented by Marbach and later developed by Reusch, has been recently still further elaborated by Klocke (J. Min., 1880, i., 53, 158), Klein, Jannettaz, Ben Saude. Klocke's first observations were made upon artificial crystals of alum. He found that each crystal (contrary to earlier statements) showed doubly refracting properties as strongly normal to an octahedral plane as in other directions. A section parallel to this plane was divided into six sectors by radial lines passing from the angles to the centre ; the directions of extinc- tion in each sector being || (parallel) and _L (perpendicular) to its outer edge, these directions consequently coinciding for each pair of opposite sectors. These sectors behaved as if made up of bands in a state of tension parallel to their longer direction ; a similar result was obtained by subjecting a six-sided octahedral and isotrope alum section to pressure i^erpendicular to two of its edges. He found further that all the sections of the same crystal, independ- ent of the crystallographic orientation, were alike as regards the direction of the tension, and that all crystals made at the same time, that is, under the same conditions, yielded identical results ; but this was not true of crystals made at different times. Further it was found that the distortion peculiar to the crystal exerted an essential effect upon the number and arrangement of the optical sectors, and that the position which the crystal occupied in the vessel during its formation was also an imjiortant factor. Later the same author (J. Min., 1881, ii., 249) has extended his observa- tions to some of the species exhibiting pseudo-symmetry. He shows, among other results, that pressure exerted normal to the vertical axis of a section of a tetragonal or hexagonal crystal which has been cut J_ c ( vert. ), changes the uni- axial interference figure into a biaxial, and with substances optically positive, the plane of the optic axes is jDarallel, and with negative substances normal, to the direction of pressure. This was observed on sections of vesuvianite and apoi^hyllite which exhibited uniaxial portions. INIany sections are divided into f(mr optical fields (biaxial) with the axial plans perpendicular to the edge. Tiie behavior of each field in a section of apophyllite consequently is (optically +, sjc above) as if in a state of tension parallel to the adjacent com- bination-edge with the prism; but with vesuvianite (optically — ) the direc- tion of tension is ])erpcndicular. This explanation is supported by tho fact that pressure exerted in the proper direction serves, in accordance with the above principles, respectively to increase or diminish the axial angle. The author also succeeded in obtaining axial interference figures visible in con- verging polarized light in gehitine sections when underpressure; the same phenomenon in parallel light had been earlier observed. CAUSE OF OPTICAL AXOMALIES OF CRYSTALS. 189 On the obseryations of Jannettaz, showing the effect of internal tension in causing double-refraction, see Bull. Soc. Min., ii., 1'2-i ; ii., 191 ; iii, 20. The results of ilie observations of Kleix (J. Min., 1880, ii., 209; 1881, i., 239) on boracite have an important bearing upon this subject. As stated above, it is included by Mallard among the pseudo-isometric species. Busing his results more especially upon the examination of crystals of dodecahedral habit, Mallard concluded that the apparent simple form is made up of twelve rhombic pyramids whose basal planes form the twelve faces of the dodecahe- dron. Baumhauer, on the basis of results of etching experiments, more par- ticularly on crystals of octahedral habit, concluded that the species was or- thorhombic, the apparent simple form being made up of six; individuals Avhose bases would coincide with the cubic planes (p. 187). The observations of Klein show that the structure of the crystals of different liabits vary — some agreeing with the scheme of Mallard— some with that of Baumhauer ; ho shows, however, very conclusively (as it seems to the writer) that this appa- rently complicated structure is probably due to internal tension produced during the growth of the crystals. Crystallographically there is no variation in angle from the requirements of the isometric system to be observed. In regard to tlie optical characters, he shows that the interior optical structure does not correspond to the exterior planes ; that the etching figures do not correspond to the optical limits ; that a change of temperature alters the relative position of the optical fields without influencing the form of the etching figures ; that the differently orientired optical portions lose their sharp limits, they change their 2:)03ition relatively, some disappearing in part or whole, and others appearing.* Klein has also made a sories of optical studies on garnet (Xachr. Ges. AViss. Gottingen, June 28, 1882), and after a review of the whole subject decides in favor of the true isometric character of the species ; the double-refraction i^henomena observed being due to secondary causes. Ben Saude (J. Min., 1882, 1., 41) has investigated analcite, and arrived at the conclusion that with it also the abnormal optical characters are to be ex- plained by internal molecular tension. He shows that the crystals are formed of different optical parts, in combinations of 30 with the cube and trapezo- hedron together, and 24 for the trapezohedron alone, the form of which changes as the outer surfaces of the crystals change. The structure can be explained in this way, as made up of pyramids going from each plane to the middle of the crystal having the plane as its base, with as many sides as there are edges to the plane ; as the outer form changes the optical structure changes correspondingly ; every edge corresponds to an optical boundary, and every plane to an optical field. All these double-refraction phenomena are explained as due to secondary causes. JMoreover, the author has proved that gelatine cast into the form of the natural crystals has on solidifying an analo- *A memoir by Mallard (Bull. Soc. Mm., v., 144, 1883) upon the effect of heat upon bo- racite crystals was received just as these pages were going to press. Mallard details the results of numerous experiments, and concludes that the effect of heat does not modify the form of the ellipsoid of elasticity, nor the position of the six different orientations which it can have ; it only modifies the choice made by each of the crystal sections between the six orientations. From this it is concluded that this ellipsoid is in fact characteristic of the crystalline reseaii of the species, and that the apparent isometric symmetry is due to the method of grouping alluded to. Analogous results were obtained with crystals of potas- sium sulphate (orthorhombie, pseudo-hexagonal like aragonite). and the conclusion is drawn from this that a perfect analogy exists between the so-called pseudo-isometric crystals and the pseudo- hexagonal. 100 KECENT PAPERS ON' HEAT AND ELECTKICITT. goiis optical structure, showing the same sections, the same directions of light- extiuction, and under favoring conditions the same position of the optic axes. Ben Saudc luis also examined pcrofskite (GckrOnte Preisschrift der Universitat Gottingen, 188:2) from the same standpoint, with refci'ence to the etching- figures and optical ])henomcna. 11.^ concludes that it is to be referred to the isometric system, and that the doul)le refraction is to bo cxnlained as caused by ciianges in the original position of equilibrium produced in the growtli of the crystals. This conclusion, hov/cver, is at varianco with the results of the observations of o'J.iers. References to some imjiortant Recent P(q)ers upon (he Siihjects of Ilecit and Electricity. A. Arzruni. Ueber -)xi^le may be divided by its molecular weight, and the result wall be the same ; tor SiOg, the molecular weight is 60 (284-2x16), hence, = -630 aa 22-63 ^^ before ; also for Al, 103 (= 2 x 27-5 -h 3 x 16), and ^^- = 0-22, etc. The atomic projjortions thus obtained are: 133. CHEMICAL MINER A.LOGY. Si 0-G30 0-220 Fe 0-094 Fe 0-013 Ca 0-415 H 0-230 2-2 2 O 2-727, 25-79, 2f5. 01 or sim])lv 6 6 •314 2-99 3 0-428 4-07 4 • again, The empirical formula is consequent!}' Si6Al3Ca4lI.j026. As in the ahove case, it is necessary, when very small quantities only of certain elenienrs are present, to neo:]ect them in the final formula, reckoning them in witli the elements which they replace, that is, with tliose of the same quantiva- lence. The degree of correspondence between the analysis and the formula deduced, if the latter is correctly assumed, depends entirely upon the accuracy of the former. Quwitivalent Matio. — In the chemical constitution of most minerals there exists a strong distinction between the basic and acidic elements, and this relation, in the case of substances of complex character, is often fixed when otherwise the composition is exceedingly varied. In the dualistic foi-mulas of the old chemistry this relation was expressed in the " oxygeii- ratio^^ which gave the ratio between the number of oxygen atoms belong- ing respectively to the bases, protoxide and sesquioxide, and to the acid. The expression, "oxygen-ratio," is not in hariiioiiy with tlie ]>ie?ent method of viewing chemical compounds, and the tei-m has consccpuiutly been, to some extent, abandoned ; the same relation, however, between the different classes of elements still exists, but the i-atio must be regarded as that exist- ing between the total quanti valences of each group of elements, and hence may be called the Quanti vai.ent Ratio.* The old formula for all the members of the gai-net family is 311, ±i, 3!Si = 3E.0, ilOs, 3Si()2, and the oxygen ratio for li, : R : Si = 1 : 1 : 2, or foi- bases to silica, 1 : 1. Here Iv may be either Ca, Mg, Fe, Mn, or Cr, and ii either Al, Fe, Or. This formula, however, written according to the new system (the quantivalence being expressed by Iloman numerals over thj symbols), is: II VI IV II RsftSisOia; or P^HliOi,!|Si3, to indicate that the oxygen is regarded as all linking oxygen. The ratio of the total quantivaleuces for each class of elements, dyads and hexada (basic), and the tetrad silicon (acidic), is: — 3x11 : VI : 3xIV, or, Q. ratio for R : R : Sif = 6 : 6 : 12, that is, 1 : 1 : 2. The same ratio for (R-f-R) : Si == 1 : 1, both of which are identical with the previously given oxygen ratio. * This relation was brought out bv Prof. Dana in 1867 (Am. J. Sci., xliv.. 89. 252. anS). and it forms the basis of all the formulas, according to the new system, in Dana's Sj-.slim of ^lineralogy, 18G8. Prof. Cooke has discussed the same subject (Am. J. Sci.. IT., xlvii. . iiH'i, 1*^(50), he calls the ratio, the Atomic Ratio ; the latter term, however, is generally used in a different sense, hence the expression Quantivalent Ratio employed here. t Throughout this work the letter R, unless otherwise mdicated, represents a btealtnt metal, and R either f e. Al, €r, Mn, where th'.' quantivalence of the double atoiii is sir. In u few cases, to indicate further relations, the sign of the quantivalence is sometimes emuioved DmORPinSM ISOMORPHISM. 199 Thus the oxygen ratio of the old system becomes tlie quantivalent ratio of the new, "a term, too, which has a wider meaning and bearing than that which it replaces." This principle of the ratio between the total qiianti- valeiices is an important one, and fundamental in the character of chemical compounds. This is well shown in tiie example here given, where, for a family of miiiei-als of so varied composition as the garnets, it remains con- stant in all varieties. Its importance is even more marlced in the many silicates wiiere R replaces 3R (as in spodumene in the pyroxene famil}-). The quantivalent ratio is obtained by multiplying the quantivalence of each class o£ elements present by their number of atoms; or by dividing the percentage amount of each element by the atomic weight and multiply by its quantivalence. When the basic or acid oxides are given, divide the percentage amount of each by the molecular weight, and multiply as before by the number expressing the quantivalence, and the result is the total quantivalence for the given element. Dimorphism. Isomorphism. A chemical compound, which crystallizes in two fornis genetically dis- tinct, is said to be dimorjjhous ; if in three, triinofpkous, or m general pleo7/iorphoHS. The phenc>menon is called dimorphism, or pleomorphism. On the other hand, chemical compounds, which are of dissimilar though analogous composition, are said to be isomoiyhous when their crystalline fornis are identical, or at least very closely related (sometimes called homceo- morpiious). Tiiis phenomenon is called isomorphism. An example oi pleoraor^ihisvx is given by the compound calcium carbon- ate (CaCOs), which is trirnorphous : appearing as calcite, as aragonite, and as haryto-calcite. As calcite, it crystallizes in the rhombohedral system, and, unlike as its many crystalline furms are, they may be all referred to the same fundamental rhombohedron, and, what is more, they have all the same cleavage and the same specific gravity (2'7), and, of course, the same optical characters. As aragonite, calcium carbonate ap|tears in orthorhom- bic crystals, whose optical characters are entirely different from those of calcite, as will be understood from the explanations made in the preceding chapter. Moreover, the specific gravity of aragonite (2'9) is higher than that of calcite (2*7). Again, as baryto-calcite, calcium carbonate crystal- lizes in a monoclinic form. The explaiuition of the phenomenon of pleomorphism in this case — and an anahjgous explanation must answer for all such cases — is to be found, not as was once proposed in a slight variation of chemical composition, but in the different conditions in which the same compound has been formed. Thus Hose has shown that the calcium carbonate precipitated from a solu- tion by the alkaline carbonates in the cold has the form of calcite, whereas, if the precipitation takes place at a temperature of IOC C, it takes the fnrm of aragonite. Moreover, he found that aragonite on heating fell to powder, and though no loss of weight took place, the specific gravity (ii"9) became that of calcite (2'7). Many other examples of pleomorphism may be given : Silica (SiOg) is trimorphous ; appearing as quartz, rhombohedral, G = 2*66 ; as tridi/miie. 200 CHE^nCAL MINEKALOGT. hexagonal, G = 2'3 ; and as asmanite, orthorhombic, G = 2*24 Titanic oxide (Ti02) is also triinorplious, the species being called rutile^ tetragonal [c — -0442), G = 4-25 ; oGtahedrite (c = 1*778), G = 3-9 ; and hrooMte, orthorhombic or nionoclinic, G = 4"15. Carbon appears in two forms, in diamond and graphite. Otlier familiar examples are pyrite and marcasite (FeSg) ; acanthite and argentite (AgaS) ; sphalerite and wiirtzite (ZnS) ; sidphur natural, orthorhombic, if artiiicial and crystallizing from a molten condition, nionoclinic. The relation in form of the species mentioned, and also of those of other dimorphous groups, will be found in Fart III., Descriptive Mineralogy. IsomorpJdum is well illustrated by the group of rhombohedral carbonates, with the general foraiula RCOs. Here R may be Ca, Mg, Fe, Mn, or Zn ; or further, in the sauie species, the E. may be represented by both Ca and Mg in varying proportions, as remarked on the following page, or both Ca and Fe, etc. The group is as follows : Calcite. Dolomite. Magnesite. Rhodochrosite. Siderite. Smithsonite. CaCOs 105° 5' Mg \ 2C^3 loV 15' MgCOg 107° 29' MnCOg 106° 51' FeCOs 107° 0' ZnCOg 107° 40'. Ankerite (parankerite), breunerite, mesitite, and pistomesite belong to the same group. All the above species have an analogous composition, and all crystallize in the rhc)mbohedi'al system, the angle of the fundamental form varying somewhat in the different cases. Mitschei'lich, who, by a series of experimental researches, established the principle of isomorphism, expressed it as follows : Suhstances, which a7'e analogous cheinicaX co7npou7ids, have the same crystalline form, or are rSOMORPHOUS. Some of the more important isomorphous groups are mentioned below, for the description of the different species reference must be made to Part III. fsometric system. — (1) The spinel group, having the general formula RKO4, including spinel MgA104, magnetite FeFe04,"chromite FeOr04. also franklinite, gahnite. etc. (2) The alum group, for example, potaah-aluni lv2AlS40i5 4-24aq, etc. (3) The gaenet group, having the general formula li^RSisOi^. Tetragonal system. — Rutile group, ROg ; including rutile TiOo, and cas- oiterite SnOo. The scnEiiLiTE gioup ; including scheelite CaWOi, stolzite FbW04, wulfenite PbM04. Hexagonal system. — iVvATiTE group ; apatite 3Ca3F2G8 + Ca(Cl, F)2, pyro- anorphite SPbsPgOg + PbCla, mimetite 3Pb3As208 + PbCl2, and vanadinite 3Pb3V208-i-PbCl2. Corundum group, ROj,; corundum AIO3, hematite FeOg. menaccanite. lihomhohedral system. — CALcrrE group, RCO3, already mentioned. Orthorhombic system. — ARAOONrpE gi'oup, RCO3; aragonite CaCOg, witherite BaCOg, strontianite SrCOg, cerussite PbCOg. JBarite group, RSO4 ; barite BaS04, celestite SrS04, anhydrite CaSOi, anglesite FbSO^. Curyso- LiTK group, general formula, R2Si04. DIM0KPHI8M — I80M0KPHISM. 201 Monoclinic system. — Copperas group ; melanterite FeS04+7aq; biebcrite CoSO^-fTaq, etc. Pyroxene group, RSiOs, etc. Monodlnic arul Triclinic. Feldspar group. The above eninneration includes only the more prominent amcng the isomorphous groups. In many other cases a close relationship exists among S[)ecies, both in form and composition, as brought out in Dana's System of Mineralogy (1S54), and as also to some extent exhibited in the grouping of the species in the descriptive part of this work. (1) It will be observed in the above that a replacement of an element in a compound by one or more other elements, chemically eqitivalent, may take place without any essential change of the crystalline form. Besides this a part of one element may be similarly i-eplaced. This is illustrated in the case of the rhombohedral carbonates : calcite has the composition CaCOs, and magnesite MgCOg; but in dolomite the place of the basic element is taken by Ca and Mg in equal pi-oportions, so that the formula may be written (^Ca+i|-Mg)C03, or more properly CaMgCgOg. Bnt besides this compound there ai'c others where the ratio of Ca to Mg is 3 : 2, also 2 : 1, and 3 : 1, etc. Further than this the Ca or Mg may be in part replaced by Mn, Fe, orZu. The mineral ankerite is one in which Ca, Mg, Fe (Mn), all enter, and in different proportions. Boricky has shown that the composition of the ankerite group of compounds ifi expressed by the formula : — CaCOs + FeCOa + a;(CaMgC206), where x may be -^, 1, f, |, f, 2, 3, 4, 5, 10. This and all similar cases are examples of isomorj^hous rtylacement. It is not essential that the replacing elements in an isomorphous series should have the same quantivalence, although this is generally true. For example, spodumene is isomorphous with the pyroxene group, though in it the bivalent element is replaced bv a sexivaleut (3R = ft). So, too, menac- n IV canite was included in the corundum group, since here RRO3 is isomor- phous with liOg. This relation of the element.", which are not equivalent, is brought out by the method of viewing the oxides presented on p. 174. (2). Minerals which crystallize in different systems may yet be isomor- ])hous, when the difference between their geometrical form is slight ; this is consjMcuously true of the members of the feldspar family. (3). Minerals may be closely related in form, although there is no ana- logy whatever between their chemical composition ; numy such cases have been noted, e.g., axinitc and glaubcrite, azurite and ej)idote. Two substances may be both homosomorphons and correspondingly (liniorphouis ; and they are then described ^L^isodhnorphoxin. Tiranic oxide (TiOg), and stannic oxide (SnOg), are both dimor])hous, and they are also hom(eomorphous severally in each of the two forms. Tliis is an example of ixodimoi'phism. There are also cases of isotrimorjyhism. Thus there ai'e the following related groups ; the angle of the rhombohedral forms here given is li : Ji ' of the orthorhombic and monoclinic / : /(for baryto-calcite 2-^ on 2-^): Rhombohedral. Orthorhombic. Monoclinic. RCO3 Calcite, 105° 5'. Aragonibe, 11«° 10'. Barytocalcifce, 95° 8'. RS04 Dreelite, 9;3'-94°. Anglesite, 108= 38'. Glauberite, 83^-83° aO*. RSOi+nRCOa Susaniiite, 94''. Leadhillite, 103= 16'. Lanarkite, 84°- 202 CUEMICAL MINERALOOr. Calcite, aragonite, and barjtocalcite form an undoubted cage of trimor phism, as has already been shown. Dreelite, anglesite, and g-lauberite constitute anotlier like series, and moreover it is closely parallel in angle with the former. In the third line we have the sulphato-caibonate sus'an- nite near dreelite in angle, leadhillite (identical with susaunite in composi- tion) near auglesite, and lanarkite, another sulphato-carbonate, near glan- berite, forming thus a third parallel line. The sulphuric acid in these sul- phato-carbonates dominates over the carbonic acid, and gives the form of the sulphates enumerated in the second line of the table. CuEMicAL Examination of Minerals. The chemical characters of minerals are ascertained {a) by the action of acids and other reagents ; (h) by means of the blowpipe assisted by a few chemical reagents ; (c) by chemical analysis. The last method is the only one by which the exact chemical composition of a minei'al can be deter- mined. It belongs, however, wholly to chemistry, and it is unnecessary to touch upon it here except to call attention to the remarks already made (p. 160) upon the essential importance of tlie use of }>ure material for analysis. The vai'ious tests and reactions of the wet and dry methods ai'e impoi'tant, since they often make it possible to determine a mineral with very little laboi, and this with the use of the minimum amount of material. a. Examination in the Wet Way. The most common chemical reagents are the three mineral acids, hydro- chloric, nitric, and sulphuric. In testing the powdered mineral with these acids, tlie important points to be noted are : (1) the degree of solubility, and (2) the phenomena attending entire or partial solution ; that is, whether a gas is evolved, pn^ducing effervescence^ or a solution is obtained without effervescence, or an insoluble constituent is separated out. Sulahllitij. — In testing the degree of solubility hydrochloric acnd is most conunonly used, though in the case of sulpiiides, and C(»mpounds of lead and silver, nitric acid is recpiired. Less often sulphuric acid, and aqua regia (nitro-hydrochloric acid), are resorted to. Many minerals are completely soluble vntkout effervescence : among these are some of the oxides, heuiatite, limonite, gothite, etc., some sulphates, many phosphates and ai-seniates, etc. Solubiliti/ with effervescence takes place when the mineral loses a gaseous ingredient, or when one is generated by the mutual decomposition of acid and mineial. Most conspicuous here are the carbonates, all of which dissolve with effervescence, giving off carbonic acid (properly carbon dioxide, CO.^), though some of them only when pulverized, or again, on the addition of heat. In applying this test dilute hydrochloric acid is employed. Sul- {jhuretted hydrogen (llgS) is evolved by some sulphides, when disst)lved in lydrochloric acid: this is true of sphalerite, stibnite, gi-eenockite, etc. Chlorine is evolved by oxides of manganese and also chromic and vanadic acid salts, when dissolved in hydiochloric acid. Kitric peroxide is given off by many metallic minerals, and also some of the lower oxides (cuprite, etc.), when treated with nitric acid. CHEMICAL EXAMINATION OF MINERALS, 203 The separation of an insoluble ingredient takes place: With many sili- cates, the silica separating sometimes as a tine powder, and again as a jelly ; in the latter case the mineral is said to gelatinise (sodalite, analcite). In order to test this point the iinely pulverized silicate is digested with strong hydrochloric acid, and the solution afterward slowly evaporated nearly to dryness. With a considerable number of silicates the gelatinization takes place only after ignition ; while others, which ordinarily gelatinize, are rendered insoluble by ignition. With many sulphides a separation of sulphur takes place when tliey are treated witli nitric acid. Compounds of titanic and tungstic acids are decomposed by hydrochloric acid with the separation of the oxides named. The same is true of salts of molybdic and vanadic acids, only that here the oxides are soluble in an excess of the acid. Compounds containing silver, lead, and mercury give with hydrochloric acid insoluble residues of the chlorides. These compounds are, however, soluble in nitric acid. When compounds containing tin are treated with nitric acid, the stannic oxide separates as a white powder. A corresponding reaction takes place under similar circumstances with minerals containing arsenic and antimony. Inaohihle minerals. — A large number of minerals are not sensibly attacked by any of the acids. Among these may be named the following oxides: corundum, spinel, chromite, diaspore, rutile, cassiterite, quartz; also cei-argyrite ; many silicates, titanates, tantalates, and columbates ; also the sulphates (barite, celestite, anglesite) ; many phosphates (xenotime, lazulite, cliildrenite, amblygonite), and the borate, boracite. h. EcamlnaMon of Minerals hy means of the Blowpipe, Blowpipe. — The simplest form of the blowpipe is a tapering tube of brass (f. 413, 1), with a minute aperture at the extremity. A chamber is advantageously 413 added (f. 413, 2) at o, to i-eceive the condensed ^p - i — \a_ ^^ moisture, and an ivory mouth-piece is often i i " 'P' ^ very convenient. In the better forms of the insti'ument (see f. 413, 3), the tip is made of solid platinum (_/), which admits of being readily cleaned when necessary. Operations with tiie blowpipe often require an uninter- mitted heat for a considerable length of time, and always longer than a single breath of the operator. It is therefore requisite that breath- ing and blowing should go on together. This may be difficult at first, but the necessary skill or tact is soon acquired. Bloiopipe-flame. — The best and most con- venient source of heat for blowpipe purposes is ordinary illuminating gas. The burner is a simple tube, flattened at the top, and cut off a little obliquely ; it thus furnishes a flame of convenient shape. A similar 204 CHEMICAL MINIJKALOGT. jet may also be used in conjunction with the ordinary Bunseu burner, it being so made as to slip down within tlie outer tube, and cut off the supply of air, thus giving a luminous flame. The gas flame required need not be more than an inch and a half in height. In place of the gas, a lamp fed with olive oil will answer, or even a good candle. The jet of the blowpipe is brought close to the gas flame on the higher side of the obliquely terminated burner. The arm of the blowpipe is inclined a little downward, and the blast of air produces an oblique conical flame of intense heat. This blowpipe flame ccnsists of two cones : an inner of a blue color, and an outer cone which is yellow. The heat is most intense just beyond the extremity of the blue flame, and the mineral is held at this point when h&fusibilitt/ is to be tested. Tlie inner flame is called the keducing flame (R.F.) ; it is characterized b}' the excess of the carbon or liydrocarbons of the gas, which at the liigh temperature present tend to combine with the oxygen of the mineral brought into it, or in other words, to reduce it. The best reducing flame is produced when the blowpipe is held a little distance from the gas flame; it should retain the yellow color of the latter. The outer cone is called the oxidizing flame (O.F.) ; it is characterized by the excess of the oxygen of the air over the carbon of the gas to be com- bined with it, and has hence an oxidizing eftect upon the assay. This flame is best produced when the jet of the blowpipe is inserted a very little in the gas flame; it should be entirely non-luminous. Su]>2)oi'ts. — Of other apparatus requii-ed, the most essential articles are those which serve to support the mineral in the flame ; these supports are : (1) charcoal, (2) platinum forceps, (3) platinum wire, and (4) glass tubes. (1) Charcoal is especially useful as a support in the case of the examina- tion of metallic minerals, where a reduction is desired. It must not crack when heated, and should not yield any considerable amount of ash on com- bustion ; that made from soft wood (pine or willow) is the best. Pieces of convenient size for holding in the hand are employed ; they should have a smooth surface, and a small cavity should be in it made for the mineral. (2) A convenient kind of platinum forceps is represented in f. 414 ; it is made of steel with platinum points. These open by means of the pins 414 pp ; other forms open by the spring of the wire in the handle. Cai-e must be taken not to heat any substance {e.g., metallic) in the forceps, which when fused might injure the platinum. (3) Platinum wire is employed with the use of fluxes, as described in another place. (4j Tiie glass tubes required are of two kinds : closed tubes, having only one open end, about four inches long ; and open tubes, having both ends open, four to six inches in length. Both kinds can be easily made by the student from ordinary tubing (best of rather hard glass), having a bore of J to ^ of an iach. CHEMICAL EXAMINATION OF MINEKALS. 205 In the way of additional apparatus, the following articles are useful ; they need no special description : hammer, small anvil, three-cornered file, mag- net, pliers, pocket-lens, and a small mortar, as also a few of the test-tubes, etc., used in the laboratory. Chemical reagents. — The commonest reagents employed are the fluxes. Tiz., soda (sodium carbonate) ; salt of phosphorus (sodiuin-amnionium phosphate); and borax (sodium biborate). The method of using thcMu ia spoken of on p. 208. Nitrate of cobalt in solution is also employed. It is conveniently kept in a small bulb from which a drop or two may be obtained as it is needed. This is used principally as a test for aluminum or magnesium with infusible minerals, as remarked beyond. The fragment of the mineral held in the forceps is first ignited in the blowpipe fiame, a drop of the cobalt solution is placed on it, and then it is heated again ; the presence of either constitu- ent named is manifested by the color assumed by the ignited mineral. It is also used as a test for zinc. Potassium bisulphate and calcium fluoride (fluorite) in powder, metallic magnesium (foil or wire), and tin foil, are othei reagents, the use of which is explained later. Test-papers are also needed, viz., blue litmus paper, and turmeric paper. The wet reagents required are: the ordinary acids, and most important of these hydrochloric acid, generally diluted one-half for use, and also barium chloride, silver nitrate, ammonium molybdate. The blowpipe investigation of minerals includes their examination, (1) in the platinum-pointed forceps, (2) in the closed tube, (3) in the open tube, (4) on charcoal, and (5) with the fluxes. (1) E ixuninatio^i in the forceps. — The most important use of the plati- num-pointed forceps is to hold the fragment of the mineral while its fusi- bility is tested. The following practical points must be regarded : (1) Metallic minerals, which when fused may injure the platinum, should be examined on charcoal ; (2) the fragment taken should be thin, and as small as can conveniently be held; (3) when decrepitation takes place, the heat must be applied slowly, or, if this does not prevent it, the mineral may be powdered and a paste made with water, thick enough to be held in the forceps or on the platinum wire ; or the paste may, with the same end in view, be heated on charcoal ; (4) the fragment whose fusibility is to be tested must be held in the hottest part of the flame, just beyond the extremity of the blue cone. In connection with the trial of fusibility, the following phenomena ma}' be observed : {a) a coloration of the flame; {J)) a swelling up (stilbite), or an exfoliation of the mineral (vermiculite) ; or (c) a glowing without fusion (calcite) ; and {d) an intumescence, or a spirting out of the mass as it fuses (scapolite). The color of the mineral after ignition is to be noted ; and the nature of the fused mass is also to be obser\ed, whether a clear or blebby glass is obtained, or a black slag, or whether magnetic or ]iot, etc. The ignited fragment, if nearly oi- (piite infusible, may be moistened with the cobalt solution and again ignited (see above) ; also, if not too fusible, it may, after treatment in the forceps, be placed upon a strip of moistened turmeric paper, in which case an alkaline reaction shows the presence of the alkaline earths. J^vjiihility. — All grades of fusibility exist among minerals, from those 206 CHEMICAL MTNERALOOT. which fuse in large fragments in the flame of the candle (stibnite, see lielow), to thos(! which fuse only on the thinnest edges in the hottest blow- l)i])c flame (In-onzite) ; and still again there are a considerable number n-lii<;h are entirely infusible {e.g., corundum). The following scale of fusibility, proposed by von Kobell, is made use of: 1, stibnite ; 2, natrolite ; 3, almandine garnet; 4, actinolite ; 5, ortlio- clase ; 6, bronzite. A little practice with these minerals will show tlie student what degree of fusibility is expressed by each number, and render him quite independent of the table; he will thus be able also to judge of his power to produce a hot flame b}' the blowpipe, which requires practice. Flame coloration. — When coloration is produced it is seen on the exterior poi'tion of the flame, and is best observed when shielded from the direct light. The presence of soda, even in small quantities, produces a yellow flame, which (except in the spectroscope) more or less completely masks the coloration of the flame due to other sub- stances ; phosphates and borates {?ive the green flame in general best when they have been pulverized and moistened with sulphuric acid ; moistening with hydrochloric acid makes the coloration in many cases (barium, strontium) more distinct. The colors which may be produced, and the substances to whose presence they are due, are as follows: {!) yaWow., sodium ; (2) \io\et, potassium ; (3) purple-red, lithimn / red, strontium,' yellowish-red, calcium (lime); (4) yellowish-green, barium, molybdenum ; emerald-green, copper • h\\\\i\\- vr^iew., ])hos2)horus (phosphates) ; yellowish-green, boron (borates) ; (5) blue, azure-blue, co2)per chloride; light-blue, arsenic ,' greenish-blue, antimony. (2) ITtating in the closed tube. — Tiie closed tube is employed to show the effect of heating the mineral out of contact with the air. A small frag- ment is taken, or sometimes the powdered mineral is inserted, though in this case with care not to soil the sides of the tube. The phenomena which may be observed are as follows : decrepitation, as shown by fluorite, calcite, etc. ; glowing, as exhibited by gadolinite ; phosp)horescence, of which fluorite is an example ; change (9/"c('y/6'/'(limouite), and here the color of the mineral should be noted l^oth when hot, and again after cooling ; fusion ^ gi^'i^i? f^ff r>.»y^«n, as mercuric oxide ; yielding w;a^^/' at a low or high temperature, which is true of all hydrous minerals ; yielding acid or allmline vapors, which should be tested l\y inserting a strip of moistened litmus or turmeric paper in the tube; yielding a sublimate, which condenses in the cold part of the tube. Of the sublimates which form in tlie tube, the following are those with which it is most important to be familiar: Sublimate yeWow, sulphur / dark brown-red when hot, and red or reddish-yellow when cold, arsenic sulphide/ brilliant black, arsenic (also giving off a garlic odoi-); black when hot, brown-red when cold, formed near the mineral by strong heating, antim.nny oxy sulphide ; dark- red, selenium (also giving the odor of decay- ing horseradish) ; sublimate consisting of small drops with metallic lustre, tellurium / sublimate gray, made up of minute metallic globules, mercury / sublimate black, lustreless, red when rubbed, mercury sulphide. (3) Heating in the open tube. — The small fragment is placed in the tube about an inch from the lower end, the tube being inclined sufficiently to pi-ovent the mineral from slipping out. The current of air, passing through CHEMICAL EXAMINATION OF MINEBALS. 207 the tube during the heating process, has an oxidizing effect. The special phenomena to he observed are the formation of a sublimate and the odor of the escaping gases. Tiie acid or alkaline character of the vapors are tested in the same way as with the closed tube. Fluorides, wiien heated in the open tube with previously fused salt of phosphorus, yield hydroflnoric acid, which gives an acid reaction with test-paper, has a peculiar pungent odor, and corrodes the glass. TJie suhlimates which may be formed, as far as they differ from those already mentioned, as obtained in the closed tube, are as follows: Subli- mate, white and crystalline, volatile, arsenous oxide ,' white, near the min- eral crystalline, fnsible to minute drops, yellowish when hot, nearly color less when cold, molyhdic oxide j sublimate white, yielding dense white fumes, at first mostly volatile, forming on the upper side of the tube, and afterward generally non- volatile on the under side of the tube, antimonous and antimoniG oxides,' sublimate dark brown when hot, lemon-yellow when cold, fusible, bismuth oxide,' sublimate gray, fusible to colorless drops, ttUurous oxide ; sublimate steel-gray, the upper edge appearing red, seleniiun ; sublimate bright metallic, Tnercury. The odors which may be perceived are the same as those mentioned in the following article. (4) Heating alone on charcoal. — The substance to be examined is placed in a shallow cavity ; it may simply be a small fragment, or, where the mineral decrepitates, it may be powdered, mixed with water, and thus the material employed as a paste. The points to be noticed are : {(.L) The odor given off after short heating. In this way the presence of sulphur, arsenic (garlic odor), and selenium (odor of decayed horseradish), may be recognized. (b) Fusion. — In the case of the salts of the alkalies the fused mass is absorbed into the charcoal ; this is also true, after long heating, of the car- bonates and sulphates of barium and strontium. (c) The infusible residue. — This may (1) glow brightly in the O.F., indi- cating the presence of calcium, strontium, magnesium, zirconium, zinc, or tin. (2) It may give an alkaline reaction after ignition : alkaline earths. (3) It may be magnetic, showing the presence of iron. {d) Tiie sublimate. — ]^'^ this means the presence of many of the metals may be determined. The color of the sublimate, both near the assay (N), and at a distance (D) ; as also when hot and when cold is to be noted. The most important of the sublimates, with the metals to which they are due, are contained in the following list: Sublimate, steel-gray (N), and dark gray (D), in H.F. volatile with a blue tlame, selenium (also giving a peculiar odor) ; white (N) and red or deep yellow (D), in KF. volatile with gi'een tlaine, tellurium j white (N) and grayish (D), arsenic (giving also a peculiar alliaceous odor); white (N) and bluish (D), an/'///ic//iy (also giving t)ff dense white fumes). Reddish-brown, silver ,' dark orange-yelh'W when liot, and lemon-yellow when cold (N), also bluish-white (D), bismuth ^ dai-k lemon-yellow when hot, sulphur-yellow when cold, lead ^ i-ed-brown (X) and orange-yellow (D), cadmium ^ yellow when hot, white on cooling, si/ic (the sul»limate becomes green if moistened with cobalt solution and again ignited); faint yellow when hot, white ou cooling, tin (the sublimatn 'iecomes bluisii-trreen when it^nited after being moistened with the col»all 208 CHEMICAL MINERALOGY. Bolr.tion, in the R.F. it is reduced to metallic tin) ; 3'ellow, sometiraet crjrg talliiie when hot, white when cold (N), bluish (D), moliihdemnn (i;j O.F the sublimate volatilizes, leaving a permanent stain of the oxide, in R.F. gives an azure blue color when touched for a moment with the flame). (5) Treatment with, the fluxes. — The three fluxes have been mentioned on p. 205. They are used either on charcoal or with the platinum wire. If the latter is employed it must have a small looj) at the end ; this is heated to redness and dipped into the powdered flux, and the adhering pailicles fused to a bead ; this operation is repeated until the loop is filled. Some- times in the use of soda the wire may at first be moistened a little to cause it to adhere. Wlien the bead is ready it is, while hot, brought in contact with the powdered mineral, some of which will adhere to it, and then the heating process may be continued. Yery little of the minei-al is in general required, and the experiment should be commenced with a minute quantity and moie added if necessary. The bead must be heated successively in the reducing and oxidizing flames, and in each case the color noted when hot and when cold. The phenomena connected with fusion, if it takes place, must also be observed. Minerals containing sulphur or arsenic, or both, must be first roasted, that is, heated on charcoal, first in the oxidizing and then in the reducinjf tlame, till these substances have been volatilized. If too much of the mineral has been added and the bead is hence too opaque to Bhow the color, it may, while hot, be flattened out with the hammer, or drawn out into a wire, or part of it may be removed and the remainder diluted with more of the flux. Borax. — The following list enumerates the different colored beads obtained with borax, and also the metals to the presence of whose cxides the colors ai-e due : Colorless J silica, aluminum, the alkaline earths, etc. (both O.F. and R.F.) ; also silver, zinc, cadmium, lead, bismuth, and nickel, O.F., and also R.F., after long heating, but when first heated, gray or turbid ; R.F., man- ganese. Yellow ^ in O.F., titanium, tungsten, and molybdenum, also zinc and cadmium, when strongly saturatetl and hot j vanadium (greenish when hot) ; iron, uranium, and chromium, when feebly saturated. Red fo broion • in O.F., iron, hot (on cooling, yellow) ; O.F., chromium, hot (yellowish-green when cold) ; O.F., uranium, hot (jiellow when cold) ; nickel, manganese, cold (violet when hot). Red ; R.F., copper, if highly saturated, cold (colorless when hot). Violet; O.F., nickel, hot (red-brown to brown on cooling); O.F. , man- ganese. Blue; O.F. and R.F., cobalt, both hot and cold; O.F., copper, cold (when hot, green). Green ; ().F., copper, hot (blue or greenish-blue on cooling), R.F,, bottle- green ; (^.F., chromium, cold (yellow to red when hot), R.F., emerald-green O.F., vanadium, cold (yellow when hot), R.F., chrome-green, cold (brown- ish when hot) ; R.F., uranium, yellowish-green (when highly saturated). Salt of Fhosphorus. — This flux gives for the most part reactions similai to those obtained with borax. The only cases enumerated here are those which are distinct, and hence those where the flux is a good test. With silicat'is this flux forms a glass in which the bases of the silicate CHEMICAL EXAMINE HON OF MINERALS, 209 are dissolved, but the silica itself is left insoluble. It appears as a skeleton readily seen floating about in the melted bead. The colors of the beads and ihe metals to whose oxides these are due, are : Blue ; R.F., tungsten, cold (brownish when hot) ; R.F., columbium, cold and when highly saturated (dirty-blue when hot). Both these give colorless beads in the O.F. Green; R.F., uranium, cold (yellowish-green when hot); O.F., molyb- denum, pale on cooling, also R.F., dirty-green when hot, green when cold. Violet ; R.F., columbium (see above) ; R.F., titanium cold (^'cllow when hot). Soda is especially valuable as a flux in the case of the reduction of the metallic oxides ; this is usually performed on charcoal. The tinely pulver- ized mineral is intimately mixed with soda, and a drop of water added to form a paste. This is placed in a cavity in the charcoal, and subjected to a strong reducing flame. More soda is added as that present sinks into the coal, and, aftei- the process has been continued some time, the remainder of the flux, the assay, and the surrounding coal are cut out with a knife, and the whole ground up in a mortar, with the addition of a little water. The charcoal is carefully washed away and the metallic globules, flattened out by the process, remain behind. Some metallic oxides are very readily reduced, as lead, while others, as copper and tin, require considerable skill and care. The metals obtained may be: iron, nickel, or cobalt, recognized by their being attracted by the magnet; or copper, marked by its red color ; bis- muth and antimony, which are brittle ; gold or silver; antimony, tellurium, bismuth, lead, zinc, cadmium, M'hich volatilize moi'e or less completely and may be recognized by their sublimates (see p. 2 A 14 = 124''- 129°. — Chrysolite, forsterite, tephroite, monticellite, etc. (5) Willemite group. Hexagonal, R A R = 116°-117°. — Willemite, diop- tase, phenacite. (c) Isometric. Ilelvite. Danalite, R2Si04 + RS. {a) Garnet group. Isometric. — Q. ratio for R : R : Si = 1 : 1 : 2. Gen- eral formula RgRSigOia. (e) Vesuvianite group. Tetragonal. — Zircon, vesuvianite. (/) Epidote group. Anisometric. — Epidote ; allanite ; zoisite ; gadoli- nite ; ilvaitc. {a) Triclinic. Axinite. Danburite. — (A) lolite. {k) Mica group). I A J = 120°. Cleavage basal perfect; optic axis o> acute bisectrix normal to the cleavage-plane. — Phlogopite ; biotite; lepido melane ; muscovite ; lepidolite. {I) Scapolite group. Tetragonal. — Sarcolite ; melon itvj ; wernerite ; ekeoergite. {m) Ilexagonal. Nephelite. Isometric. — Sodalite ; hailjnite ; nosite j leucite. CLASSIFICATION OF SPECIES. 219 Feldspar groujp. Monoclinic or tricliuic. /A 7 near 120° ; Q. raiio for R : R = 1 : 3. Anorthite ; labradorite ; andesite ; hyalophano ; oligo- clase ; albite ; orthoelase (microcline). (7) Sl'bsilicates. — {a) Q. ratio for bases to silicon, 4 : 3. Chondrodite Touriiialiiie. (5) Q. ratio for bases to silicon, 3 : 2. Genlenite. — Andaliisite; fibrolite; cyanite (AlSiOg). — Topaz ; euclase ; datolite. — Giiarinite ; titanite ; keil- haiiitc ; tscbeff kinite. (c) Q. ratio for bases to silicon, 2 : 1. Staurolite. B. Hydrous Silicates — General Section. BisiLTCATEs. — Pectolite ; laumontite ; okenite. — ChrysocoUa ; alipite, etc. Unisilicates. — Calamine ; prehnite. — Thorite. Pyrosmalite. — Apophyl- lite. SuBsiLiCATES. — Alloplianc. Zeolite Section. Thorasonite ; natrolite ; scolecite ; mesoHte. — Levyniite. — Analcite.— Chabazite ; grneliuite ; herschelite. — Phillipsite. — Harmotome. — Stilbite ; heulandite. Margarophyllite Section. BisiLicATEs. — Talc Pyropbyllite. — Sepiolite ; glauconite. Unisilicaiks, — Serpentine group. Serpentine ; deweylite ; genthite. Kaolinite group. Ivaolinite ; pholerite ; halloysite. Pinlte group. Pinite, etc. ; palagonite. Hydro-mica group. Fabliiuite ; margarodite ; damourite ; paragonite ; cookeite. — llisiugerite. Chlorite group. Yerraiculites, Q. ratio of bases to silicon, 1 : 1. Pyro- Bclerite ; jefferisite, etc. — Penninite. — Ripidolite ; prochlorite. — Cliloritoid ; margarite. Seybertite. 2. TANTALATES, C0LUMBATE3. Pyrochlore. — Tantalite ; columbite ; yttrotantalite ; saraarskite ; eiixe- nite ; aeschynite, etc. 3. PHOSPHATES, ARSENATES, VANADATES. Anhydeous. — Xenotime YgPaO, ; pucherite. — Descloizite. Hexagonal. — Formula 3Eg(P,A8,v)208 + R(Cl,F)3. Apatite; pyromof- phite ; raimetite ; vanadinite. Wagnerite ; luonazite. — Triphylite ; triplite. — Amblygcnite (liebronitc) 220 DESCEIFflVE MmERALOGT. nYDROUs. — Pharmacolite; brnsliite. — Yivianite ; crjthrite. — Libethinitc; oliveiiite. — Lirocoiiite ; pseiidomalacliite. — Clinoclasite. — Lazulite ; scoro dite ; wavellite ; pharmacosiderite. — Childreiiite. — Turquois ; cacoxenite. — Torbernite ; autnnite. Hydrous antiinonate. — Bindheiinite. 4. BORATES. Sassolite ; sussexite ; ludwigite. — Boracite ; ulexite ; priceite. — War- wickite. 5. TUNGSTATES, general formula RWO4 ; MOLYBDATES, RM0O4; CHROMATES, RCr04. Wolframite ; scheelite ; stolzite. — Walfenite. — Crocoite ; phoenicochroite. 6. SULPHATES. Anhydrous. — General formula RSO4. Orthorhorabic I A I = lOO^-lOS**. — Barite ; celestite ; anhydrite ; anglesite ; zinkosite ; leadhillite. Caledonite. — Dreelite; susanuite ; connellite. — Glauberite ; lanai'kite. Hydrous sulphates. — Mirabilite. — Gjpsum. — Polyhalite. — Epsomite. Ooj}jj>eras groujp. Chalcanthitej CuS04 + 5aq, also the other vitriols, RS04 + 7aq. Copiapite. — Aluminite, — Linarite ; brochantite, etc. Tellurites. — Montanite, Bi2Te06 + 2aq. 7. CARBONATES. Anhydrous. — CoZcite group. Rhombohedral. General formula, RCO3. — Calcite ; dolomite ; magnesite ; siderite ; rhodochrosite ; smithsonite. Aragonite grouj). Orthorhombic. — Aragonite ; witherite ; strontiauite ; cerussite ; baryto-calcite. — Phosgenite. Hydrous carbonates. — Gaylussite, — Hydromagnesite. — Hy drozincitc ; malachite ; azurite. — Bismntite, etc. VI. HYDROCARBON COMPOUNDS. I. NATIVE ELEMENTS. GOLD. IscmeLric. The octahedron and dodecahedi-on the most comnic n forma Crystals sometimes acicular through elongation of octa- 415 hedral or other forms ; also passing into filiform, reti- cnlated, and arborescent shapes ; and occasionally spongiform from an aggregation of filaments ; edges of crystals often salient (f. 415), Cleavage none. Twins: twinning-plane octahedral. Also massive and in thin laminge. Often in flattened grains or scales, and rolled masses in sand or gravel. ![.=: 2-5-3. G. = 15-G-19-5 ; 19-30-19-34, when quite pure, (Jr. Rose. Lustre metallic. Color and streak various shades of gold-yellow, sometimes inclining to silver-white. Very ductile and malleable. Composition, Varieties.— Gold, bat containing silver in different proportions, and some- times also traces of copper, iron, bismuth (?«nfZrf(?«?Y<'), palladium, rhodium. Var. 1. Ordinary. Containing O'Ki to 1() p. c. of silver. Color varying, accordingly, from deep gold-yellow to pale yellow; G. =19-15'5. 2. Argentiferous; Electrum. Color pale yellow to yellowish white; G. =15o-13"5. Ratio for the gold and silver of 1 : 1 corresponds to 85 "5 p. c. of silver, 2 : 1, to 21-6 p. c. The average proportion of gold in the native gold of California, as derived from assays of several hundred millions of dollars' worth, is 880 thousandths ; while the range is mostly between 870 and 890 (Prof. J. C. Booth, of U. S. Mint). The range in the metal of Australia is mostly between 900 and 9G0, with an average of 925. The gold of the Chaudiere, Canada, contains usually 10 to 15 p c. of silver ; while that of Nova Scotia is very nearly pure. The Chilian gold afforded Domeyko 84 to 9(3 per cent, of gold and 15 to 8 per cent, of sUver. (Ann. d. Mines, IV. vi. ) Pyroguostic and other Chemical Characters. — B.B. fuses easily. Not acted on by fluxes. Insoluble in any single acid ; soluble in nitro-hydrochloric acid (aqua-regia). D.flf. — Readily recognized by its malleability and specitic gravity. Distinguished by its insolubility ia nitric acid from pyrite and chalcopyrite. Observations. — Native gold is found, when in situ, with comparatively small exceptions, in the quartz veins that intersect metamorphic rocks, and to some extent in the wall rock of these veins. The metamorphic rocks thus intersected are mostly chloritic, talcose, and argillaceous schist of dull green, dark gray, and other colors ; also, much less commonly, mica and homblendic schist, gneiss, dioryte, porphyry ; and still more rarely, granite. A laminated quart/yie, called itacolumyte, is common in many gold regions, as those of Brazil and North Carolina, and sometimes specular schists, or slaty rocks containing much foliated Bpecular iron (hematite), or magnetite in grains. The gold occurs in the quartz in strings, scales, plates, and in masses which are sometimes an agglomeration of crystals ; and the scales are often invisible to the naked eye, massive quartz that apparently contains no gold frequently yielding a considerable percentage to the Rssayer. It is always very irregularly distributed, and never in continuous pure bands of metal, like many metallic ores. It occurs both disseminated through the mass of the quartz, and ia its cavities. The associated minenUs are : pyrite, which far exceeds in quantity all others, and is generally auriferous ; next, chalcopyrite, galenite, sphalerite, arsenopj-nte, each frequently auriferous ; often tetradymite and other tellurium ores, native bismuth, stib- nite, magnetit,e. hematite ; sometimes barite, apatite, fluorite, siderite, chrysocoUa. The gold of the world has been mostly gathered, not directly from the quartz veins, but 222 DESCRIPTIVE MINERALOGY. from the gravel or sands of rivers or valleys in anriferous regions, or the slopes of monntaini or hills, whose roeks contain in some part, and generally not far distant, auriferous veins , Buch nines are often called alluvial wnshingn ; in California pktcei'-digcjings. Most of the gold of the Urals, Brazil, Australia, and all other gold regions, has come from such alluvial wash- ings. The alluvial gold is usually in flattened scales of different degrees of fineness, the size depending partly on the original condition in the quartz veins, and partly on the distance to which it has been transported. Transportation by running water is an assorting process ; the coarser particles or lai'gest pieces requiring rapid currents to transport them, and dropping fu-st, and the finer being carried far away — sometimes scores of miles. A cavity in the rocky fclopes or bottom of a valley, or a ]ilace where the waters may have eddied, generally proves in such a region to be a pocket full of gold. In the auriferous sands, crs'stals of zircon are very common ; also garnet and cyanite in grains; often also moaazite, diamonds, topaz, magnetite, corundum, iridosmine, platinum. The zircons ai'e sometimes mistaken for diamonds. Gold exists more or less abundantly over all the continents in most of the regions of crystal- line rocks, especially those of the semi- crystalline schists ; and also in some of the large islands of the world where such rocks exist. In Europe, it is most abundant in Hiangaiy and in Transylvania ; it occurs also in the sands of the Rhine, the Reuss, the Aar, the Rhone, and the Danube ; on the southern slope of the Pennine Alps, from the Simplon and Monte Rosa to the valley of Aosta ; in Piedmont ; in Spain, formerly worked in Asturias ; in many of the streams of Cornwall ; near Dolgelly and other parts of North Wales ; in Scotland ; in the county of Wicklow, Ireland ; in Sweden, at Edelfors. In Asia, gold occurs along the eastern flanks of the Urals for 500 miles, and is especially abundant at the Beresov mines near Katharinenburg (lat. 5(i^ 40' N. ) ; also obtained at Petro- pavlovski (,60" X.) ; Nischne Tagilsk (59^ N.) ; Miask, near Slatoust and Mt. Ilmen (55° N., where the largest Russian nugget was found), etc. Asiatic mines occur also in the CaUaa Mountains, in Little Thibet, Ceylon, and Malacca, China, Corea, Japan, Formosa, Sumatra, Java, liomeo, the Philippines, and other East India Islands. In Africa, gold occurs at Kordofan, between Darfour and Abyssinia ; also, south of the Sahara in Western Africa, from the Senegal to Cape Palmas ; in the interior, on the Somat, a day's journey from Cassen ; along the coast opposite Madagascar, between 22^ and 85° S., supposed by some to have been the Opliir of the time of Solomon. In South America, gold is found in B^'azil ; in New Granada ; Ohfli ; in Bolivia ; sparingly in Peru. Also in Central America, in Honduras, San Salvador, Guatemala, Costa Rica, and near Panama ; most abundant in Honduras. In North America, there are numberless mines along the mountains of Western America, and others along the eastern range of the Appalachians from Alabama and Georgia to Labra- dor, besides some indications of gold in portions of the intermediate Aichean region about Lake Superior. They occur at many points along the higher regions of the Rocky ilountains, in Mexico, and in New Mexico, in Arizona, in the San Francisco, Wauba, Yuma, and other districts ; in Colorado, abundant, but the gold largely in auriferous pyrite ; in Utah, and Idaho, and Montana. Also along ranges between the summit and the Sierra Nevada, in the Humboldt region and elsewhere. Also in the Sierra Nevada, mostly on its western slope (the mines of the eastern being principally silver mines). The auriferous belt may be said to begin in the Calif omian peninsula. Near the Tejon pass it enters California, and beyond for 180 miles it is sparingly auriferous, the slate rocks being of small breadth ; but beyond this, northward, the slates increa.se in extent, and the mines in number and productiveness, and they continue thus for 200 miles or more. Gold occurs also in the Coast ranges in many localities, but mostly in too small quantities to be profitably worked. The regions to the north in Oregon and Washington Territory, and the British Possessions farther north, as also our possessions in Alaska, are at many points auriferous, and productively so, though to a less extent than California. In eastern North America, the mines of the Southern United States produced before the California discoveries, in 1S49, about a million of dollars a year. They are mostly confined to the States of Virginia, North and South Carolina, and Georgia, or along a line from the Rappahannock to the Coosa in Alabama. But the region may be said to extend north to Canada ; for gold has been found at Albion and Madrid in Maine ; Canaan and Lisbon. N. H. ; Bridgewater, Vermont ; Dedham, Mass Traces occur also in Frauconia to\\'nship, Mont- ^omcv/ Co. . Pennsylvania. In Canada, gold occurs to the south of the St. Lawrence, in the ■oil on the Chaud'^re, and over a considerable region beyond. In Nova Scotia, mines are worked near Halifax and elsewhere. In Australia, which is fully equal to California in productiveness, and much superior in the purity of the metal, the principal gold mines occur along the streams in the mountains ot N. S. Wales (S. E. Australia), and along the continuation of the same range in Victoria (S. AuBtraUa). NATIVE ELEMENTS. 223 SILVER. Isometric. Cleavage none. Twins : twinning-plane octahedral. Com- monly coarse or fine filiform, reticulated, arborescent ; in the latter, the branches pass off either (1) at right angles, and are crystals (usually octa- hedrons) elongated in the direction of a cubic axis, or else a succession of partly overlapping crystals ; or (2) at angles of 60°, they being elongated in the direction of a dodecahedral axis. Crystals generally obliquely pro- longed or shortened, and thus greatly distorted. Also massive, and in plates or supei-ficial coatings. H. = 2-5-8. G.=10-l-ll-l, when pure lO'o. Lustre metallic. Color and stieak silver-white ; subject to tarnish, by which the color becomes gi-ayish-black. Ductile. Oomp., Var. — Silver, with some copper, gold, and sometimes platinum, antimony, bismuth, mercuiy. Ordinary, {a) crystallized ; (b) filiform, arborescent ; (c) massive. Auriferous. Contains 10 to 30 23. c. of gold ; color white to pale brass-yellow. There is a gradual passage to argen- tiferous gold. Cwpriferous. Contains sometimes 10 p. c. of copper. Pyr., etc. — B. B. on charcoal fuses easily to a silver- white globule, which in O.F. gives a faint dark- red coating of the oxide; crystallizes on cooling. Soluble in nitric acid, and deposited again by a plate of copper. Obs. — Native silver occurs in masses, or in arborescent and filiform shapes, in veins travers- ing gneiss, schist, porphyry, and other rocks. Also occurs disseminated, but usually invisibly, hi native copper, galenite, chalcocite, etc. The mines of Kongsberg, in Norway, have afforded magnificent specimens of native silver. The principal Saxon localities are at Freiberg, Schueeberg, and Johanugeorgenstadt ; the Bohemian, at Przibram, and Joachimsthal. It also occurs in small quantities with other ores, ac Andreasberg, in the Harz ; in Suabia ; Hungary ; at Allemont in Dauphiny ; in the Ural near Beresof ; in the Altai, at Zmeofl: ; and in some of the Cornish mines. Mexico and Peru have been the most productive countries in silver. In Mexico it has been obtained mostly from its ores, while in Peru it occurs priricii>ally native. In Durango, Sinaloa, and Sonora, in Northern Mexico, are noted mines affording native silver. In the United States it is disseminated through much of the copper of Michigan, occa.sion- -illy in spots of some size, and sometimes in cubes, skeleton octahedrons, etc., at various mines. In Idaho, at the " Poor Man's lode," large masses of native silver have been ob- tained. In Nevada, in the Comstock lode, it is rare, and mostly in filaments ; at the Ophir mine rare, and disseminated or filamentous ; in California, sparingly, in Silver Mountain dia- tricl, Alpine Co- ; in the Maris vein, in Los Angeles Co. ; in the township of Ascot, Canada. PLATINUM. Isometric. Rarely in cubes of octahedrons. Usuall}'' in grains ; occa- sionally in irregular lumps, rarely of large size. Cleavage none. H.=4-4-5. G. = 16-19; 17-108, small grains, 17-608, a mass. Breith. .Lnstre metallic. Color and streak whitish steel-gray ; shining. Opaque. Ductile. Fracture hackly. Occasionally magneti-polar. Oomp. — Platinum combined with iron, iridium, osmium, and other metals. The amount of iron varies from 4-20 p. c. Pyr., etc. — Infusible. Not affected by borax or salt of phosphorus, except in the state ol tine dust, when reactions for iron and copper may be obtained. Soluble only in heated nitro- L t'drochloric acid. 224 DESCRIPTIVE MTNERALOGr. Diflf.— Distinguished by its malleability, high specific gravity, infusibility, and entire insol ability in the ordinary acids. Obs — Platinum was first found in pebbles and small grains in the alluvial deposits of th« river Pinto, in the district of Choco, near Popayan, in South America, where it received its name plntiim, from platn, silver. In the province of Antioquia, in Brazil, it has been found in auriferous regions in syenite (Boussingault). In Russia, it occurs at Nischne Tagilsk, and Goroblagodat, in the Ural, in alluvial material. Formerly used as coins by the Russians. Russia affords annually about 800 cwt. of platinum, which is nearly ten times the amount from Brazil, Columbia. St. Domingo, and Borneo. Platinu m is also found on Borneo ; in the sands of the Rhine ; at St. Aray, val du Drac ; county of Wicklow, Ireland; on the river Jocky, St. Domingo ; in California, but not abun- dant : in traces with gold in Rutherford Co., North Carolina ; at St. Francois Beauce, etc., Canada East. Platiniuidium. — Platinum and iridium in different proportions. Urals ; Brazil, PALLADIUM. Isometric. In minute octahedrons, Haid. Mostly in grains, sometimes composed of diverging fibres. II. = 4-5-5. G. = ll-3-ll-8, Wollaston. Lustre metallic. Color whitish Bteel-gray. Opaque. Ductile and malleable. Oomp, — Palladium, alloyed with a little platinum and iridium, but not yet analyzed. Obs.^Palladium occurs with platinum, in Brazil, where quite large masses of the metal are sometimes met with ; also reported from St. Domingo, and the Ural. Palladium has been employed for balances ; also for the divided scales of delicate apparatus, for which it is adapted, because of its not blackening from sulphur gases, while at the same time it is nearly as white as silver. miDOSMINi;. Osmiridium. Hexagonal. Rarel}'^ in hexagonal prisms with replaced basal edges. Commonly in irregular flattened grains. IL = 6-7. G. = 19-3-21-12. Lustre metallic. Color tin- white, and light BteeVgray. Opaque. Malleable with difficulty. Comp., Var — Iridium and osmium in different proportions. Two varieties depending on these proportions have been named as species, but they are isomorphous, as are the metals (Gr. Rosej. Some rhodium, platinum, ruthenium, and other metals are usually present. Var. 1. Neirjanskite^ILaidL.; H.=7; G. = 18-8-19o. Inflatscales; color tin-white. Over 40 p. c. of Iridium. Probably IrOs. 2. tUsserskiie, Haid. In flat scales, often six-sided, color grayish-white, steel-gray. G. - 30-212. Not over 80 p. c of iridium. One kind from Nischne Tagilsk afforded Berzehus. IrOs4=Iridium 19*9, osmium 801=:100 ; G. =21-118. Another corresponded to the formula IrOs3. Pyr., etc. — At a high temperature the eisserskite gives out osmium, but undergoes no further change. The newjanskite is not decomposed and does not give an osmium odor until fused with nitre. Diff. — Distinguished from platinum by its superior hardness. Obs. — Occurs with platinum in the province of Choco in South America ; in the Ural moun- tains ; in Australia. It is rather abundant in the auriferous beach sands of northern Cali- foi-nia. occurring in small bright lead -colored scales, sometimes six-sided. Also traces in tlia g-old- washings on the rivers du Loup and des Plantes, Canada. MERCURY. Quicksilver. Gediegeu Quecksilber, Oerm, Isometric. Occurs in small fluid globules scattered through its gangua G.= 13.568. Lustre metallic. Color tin- white. Opaque. NATIVE ELEMENTS. 225 Comp. — Pure mercury (Hg) ; "with sometimes a little silver. Pyr., etc. — B.B., entirely volatile. Dissolves readily in nitric acid. Obs. — Mercury in the metallic state is a rare mineral ; the quicksilver of commerce is ob- tained mostly from cinnabar, one of its ores. The rooks affording the metal and its ores are mostly clay shales or schists of different geological ages. Its most important mines are those of Idria in Carniola, and Almaden in Spain. It ia found in small quantities in Carinthia, Hungary, Peru, and other countries ; in California, especially in the Pioneer mine, in the Napa Valley. AMALGAM. Isometric. The dodecahedron a common form, also the cube and octa hedron in combination (see f. 40, 41, etc., p. 15). Cleavage : dodecahedral hi traces. Also massive. H.=3-3-5. G. = 13.75-14. Color and streak silver- wliite. Opaque. Fracture conchoidal, uneven. Brittle, and giving a grating noise when cut with a knife. Comp. — Both Ag Hg (=Silver 35*1, mercury, 64-9), and AgjHgs (=Silver 26 '5, and mer- cury, 73 '5), are here included. Pyr., etc, — B.B., on charcoal the mercury volatilizes and a globule of silver is left. In the closed tube the mercury sublimes and condenses on the cold part of the tube in minute glo- bules. Dissolves in nitric acid. Obs. — From the Palatinate at Moschellandsberg. Also reported from Bosenau in Hungary, Sala in Sweden, Allemont in Dauphine, Almaden in Spain. Arquerite. — Composition Ag,2Hg=silver 86-6, mercury, 13-4=100. Chill KoNOS- BERGITE, AgisHg (?) Kongsberg, Norway. COPPER. Isometric. Cleavage none. Twins : twinning-plane octahedral, very common. Often filiform and arborescent; the latter with the bra?iche8 passing off usually at 60°, the supplement of the dodecahedral angle. Also massive. H. =2-5-3. G.=8'838, "Whitney. Lustre metallic. Color copper-red. Streak metallic shining. Ductile and malleable. Fracture hackly. Comp. — Pure copper, but often containing some silver, bismuth, etc. Pyr,, etc. — B.B., fuses readily ; on cooling, becomes covered with a coating of black oxiae. Dissolves readily in nitric acid, giving ofiE red nitrous fumes, and producing a deep azure-blue solution upon the addition of ammonia. Obs. — Copper occurs in beds and veins accompanying its various ores, and is most abundant in the vicinity of dikes of igneous rocks. It is sometimes found in loose masses imbedded in the soil. Found at Turinsk, in the Urals, in fine crystals. Common in Cornwall. In Brazil, Chili, Bolivia, and Peru. At Walleroo, Australia. This metal has been found native throughout the red sandstone (Triassico-Jurassic) region of the eastern United States, in Massachusetts, Connecticut, and more abundantly in New Jersey, where it has been met with sometimes in fine crystalline masses. No known locality exceeds in the abundance of native copper the Lake Superior copper region, near Keweenaw Point, where it exists in veins that intersect the trap and sandstone, .u d where masses ol immense size have been obtained. It is associated with prehnite, d itolite, analcite, laumon- tite, pectolite, epidote, chlorite, wollastonite, and sometimes coats amygdules of calcite, etc. , in amygdaloid. Native copper occurs sparingly in California. Also on the G-ila riv«i in Arizona ; in large drift masses in Alaska. 16 226 DESCKIPTITE MINERALOGY. IRON.* Isometric. Cleavage octahedral. II.=4-5. G.=7'3-7*8. Lustre metallic. Color iron-graj. Streak shin iiig. Fracture hackly. Malleable. Acts strongly on the magnet. Obs> — The occurrence of masses of native iron of terrestrial origin has been several times reported, but it is not yet placed beyond doubt. The presence of metallic iron in grains in basaltic rocks has been proved by several observers. It has also been noticed in other related rocks. The so-called meteoric iron of Ovifak, Greenland, found imbedded in basalt, is con- sidered by some authors to be terrestrial. Meteoric iron usually contains 1 to 20 per cent, of nickel, besides a small percentage of other metals, as cobalt, manganese, tin, copper, chromium ; also phosphorus common as a phosphuret (schreibersite), sulphur in sulphurets, carbon in some instances, chlorine. Among large iron meteorites, the Gibbs meteorite, in the Yale College cabinet, weighs 1,685 lbs. ; it was brought from Red River. The Tucson meteorite, now in the Smithsonian Institution, weighs 1,400 lbs. ; it was originally from Sonora. It is ring-shaped, and is 49 inches in its greatest diameter. Still more remarkable masses exist in northern Mexico ; also in South America ; one was discovered by Don Rubin de Cells in the district of Chaco-Gualamba, whose weight was estimated at 32,000 lbs. The Siberian meteorite, discovered by Pallas, weighed originally 1,600 lbs. and contained imbedded crystals of chrysolite. Smaller masses are quite common. Zinc- -Native zinc has been reported to occur in Australia; and more recently Mr. W. D. Marks reports its discovery in Tennessee, under circumstances not altogether free from doubt. Lead. — Native lead occurs very sparingly. It has been found in the Urals, in Spain, Ireland, etc. Dr. Genth speaks of its discovery in the bed rock of the gold placers at Camp Creek, Montana. Tin is probably only an artificial product. ARSENIC. Ehombohedral. ^ A 7? = 85° 41', OaB = 122° 9', c = 1-3779, Miller. Cleavage : basal, imperfect. Often granular massive ; sometimes reticu- lated, reniform, and stalactitic. Structure rarely columnar. H. = 3-5. G. = 5-93. Lustre nearly n)etallic. Color and streak tin- white, tarnishing soon to dark-gray. Fracture uneven and tine granular. Comp. — Arsenic, often with some antimony, and traces of iron, silver, gold, or bismuth. Pyr. — B.B., on charcoal volatilizes without fusing, coatsthecoal with white arsenous oxide, and affords the odor of garlic ; the coating treated in R.F. volatilizes, tinging the flame blue. Obs. — Native arsenic commonly occurs in veins in crystalline rocks and the older schists, and is often accompanied by ores of antimony, red silver ore, realgar, sphalerite, and other metallic minerals. The silver mines of Saxony afford this metal in considerable quantities ; also Bohemia, the Harz, Transylvania, Hungary, Norway, Siberia ; occurs at Chanarcillo, and elsev/here in Chili; and at the mines of San Augustin, Mexico. In the United States it has been observed at Haverhill and Jackson, N. H., at Greenwood, Me. ANTIMONY. Ehombohedral. BaI2 = S7° 35', Kose ; A R = 123= 32' ; c = 1-3068. 2a2 = 89°25'. Cleavage: basal, highly perfect ;—-i distinct. Generally massive, lamellar ; sometimes botryoidal or reniform with agranular texture * The asterisk in this and similar cases indicates that the species is mentioned again in the Supplementary Chapter, pp. 420 to 440. NATIVE ELEMENTS. 227 H.=3-3-5. G.= 6- 646-6-72. Lustre metallic. Color and streak tin- white. Yery brittle. Comp, — Antimony, containing sometimes silver, iron, or arsenic. Pyr, — B.B., on charcoal fuses, gives a white coating in both O. and R.F. ; if the bloving be intermitted, the globule continues to glow, giving off white fumes, until it is finally crusted over with prismatic crystals of aatimonous oxide. The white coating tinges the R.F. bluish- green. Crystallizes readily from fusion. Occurs near Sahl in Sweden ; at Andreasberg in the Harz ; at Przibram ; at Allemont in Dauphiny; in Mexico ; Chili; Borneo; at South Ham, Canada ; at Warren, N. J, rare ; at Prince William antimony mine, N, Brunswick, rare. Allemontite. — Arsenical antimony, Sb^LSj. Color tin-white or reddish-gray. Occurs at Allemont ; in Bohemia ; the Harz. BISMUTH. Gediegen Wismuth, Oerm. Hexagonal. 12 A B = 87° 40', G. Rose ; 6> A 7? = 123° 36' ; c = 1-3035. Cleavage : basal, perfect; 2, — 2, less so. Also in reticulated and arbores- cent shapes ; foliated and granular. H. = 2-2-5. G. = 9-727. Lustre metallic. Streak and color silver-white, with a reddish hue ; subject to tarnish. Opaque. Fracture not observable. Sectile. iirittle when cold, but when heated somewhat malleable. Comp., Var. — Pure bismuth, with occasional traces of arsenic, sulphur, tellurium. Pyr., etc. — B.B., on charcoal fuses and entirely volatilizes, giving a coating orange-yellow while hot, and lemon-yellow on cooling. Dissolve'! in nitric acid ; subsequent dilution causes R white precipitate. Crystallizes readily from fusion. Diff — Distinguished by its reddish color, and high specific gravity, from the other brittle metals. Obs, — Bismuth occurs in veins in gneiss and other crystalline rocks and clay slate, accom- panying various ores of silver, cobalt, lead, and zinc. Abundant at the silver and cobalt mines of Saxony and Bohemia ; also found in Norway, and at Fahlun in Sweden. At Wheal Spamon, and elsewhere in Cornwall, and at Carrack Fell in Cumberland ; at the Atlas mine, Devonshire ; at Meymac, Correze ; at San Antonio, Chili ; Mt. Illampa (Sorata), in Bolivia ; in Victoria. At Lane's mine in Monroe, and near Seymour, Conn., in quartz ; occurs also at Brewer'a mine, Chesterfield district, South Carolina ; in Colorado. TELLURIUM.* Hexagonal, BaB= S6° 57', G. Rose ; OaB = 123" 4', c = 1-3302. In six-sided prisms, with basal edges replaced. Cleavage : lateral perfect, basal imperfect. Commonly massive and granular. H.=:2-2'5. G,=6*l-6*3. Lustre metallic. Color and streak tin-white Brittle. Comp. — According to Klaproth, Tellurium 92-55, iron 7'20, and gold 0"25. Pyr. — In the open tube fuses, giving a white sublimate of tellurous oxide, which B.B. fuses to colorless transparent drops. On charcoal fuses, volatilizes almost entirely, tinges th« Qame green, and gives a white coating of tellurous oxide. Obs. — Native tellurium occurs in Transylvania (whence the name Sylvanite) ; also at the Red Cloud mine, near Gold Hill, Boulder Co., Colorado. 228 DE8CKIPTIVE MINERALOGY. 417 NATIVE SULPHUR. Orthorhombic. /a7 = 101° 46', O A\-l = 113° 6'; c:b:4\ 11 % & J curved faces, as in f. 419 (3-f) ; f. 420 is a distorted form. Cleavage ; octahedral, highly perfect. Twins : twinning-plane, octahedral ; f . 418, ie NATIVE ELEIVIENTS. 229 an elliptic twin of f. 419, the middle portion between two opposite sets of six planes being wanting. Rarely massive, 11.-— 10. G. =3.5295, Thompson. Lustre brilliant adamantine. Color white or colorless : occasionally tinged yellow, red, orange, green, blue, brown, sometimes black. Transparent; translucent when dark colored. Fracture conchoid al. Index of i-efraction 2*4. Exhibits vitreous electricity w hen rubbed. Comp. — Pure carbon, isometric in crystallization. Var. — 1 . OnU/iari/, or crystallized. The crystals often contain numerous microscopic cavi- ties, as detected by Brewster ; and around these cavities the diamond shows evidence, by polarized light, of lompression, as if from pressure in the included gas when the diamond was crj'stallized. The coarse varieties, which are unfit, in consequence of imperfections, foi use in jewelry, are called bort ; they are sold to the trade for cutting purposes. -J. Jlasnive. Ill black pebbles or masses, called aobonado, occasionally 1,000 carats in weight. H =10 ; G. =3 012-3 41(J. Consists of pure carbon, excepting OS? to 2-07 p. c. (BrazU). 3. Ant/inicit/c. Like anthracite, but hard enough to scratch even the diamond. In glo- bules or mammiilary masses, consisting partly of concentric layers ; fragile ; G. = 1"6G; com- position. Carbon 97, hydrogen 0'5, oxygen 1 o. Cut in facets and polished, it refracts and disperses light, wich tlie white lustre peculiar to the diamond. Locality unknown, but sup- posed to come from Brazil. Pyr., etc. — Burns, and is wholly consumed at a high temperature, producing carbonic dioxide. It is not acted on by acids or alkalies. Diflf. — Distingu shed by its extreme hardness, brilliancy of reflection, and adamantine lustre. Obj — The diamond often occurs in regiims that afford a laminated granular quartz rocii, called itneolumi/te, which pertains to the talcose series, and which in thin slabs is more or less flexible. This rock is found at the mines of Brazil and the Urals ; and also in Georgia and North Carolina, where a few diamonds have been found. It has also been detected in a species of conglomerate, composed of rounded siliceous pebbles, quartz, chalcedony, etc., cemented by a kind of ferruginous clay. Diamonds are usually, however, washed out from the soil. The Ural diamonds occur in the detritus along the Adolfskoi rivulet, where worked for gold, and also at other places. In India the. diamond is met with at Purteal, between Hyderabad and Masulipatam, where the famous Kohinoor was found. The locality on Borneo is at Pontiana, on the west side of the Ratoos mountain. Also found in Australia. The diamond region of South Africa, discovered in 18i)7, is the most productive at the present time. The diamonds occur in the gravel of the Vaal river, from Potchefstrom, cap- ital of the Transvaal Republic, down its whole course to its junction with the Orange river, and thence along tha latter sti-eam for a distance of 60 miles. In addition to this the dia- monds are found also in the Orange River Republic, in isolated fields or Pdu.i. of which Du Toit's Pan is the most famous. The number of diamonds which have been found at the Cape is very large, and some of them are of considerable size. It has been estimated that the value of those obtained from March, 1807, to November, 1875, exceeded sixty millions of dollars. As a consequence of this production the market value of the stones has been much dimin- ished. In the United States a few crystals have been met with in Rutherford Co., N. C, and Hall Co., <;a. ; they occur also at Portis mine, Franklin Co., N. C. (Genth) ; one handsome one, over ^ in. in diameter, in the village of Manchester, opposite Richmond, Va. In California, at Cherokee ravine, in Butte Co. ; also in N. San Juan, Nevada Co., and elsewhere in the gold washings. Reported from Idaho, and with platinum of Oregon. The largest diamond of which we have any knowledge is mentioned by Tavernier as in possession of the Great Mogul. It weighed originally 900 carats, or 2769 3 grains, but waa reduced by cutting to 861 grains. It has the form and size of half a hen's egg. It was found in 1550, in the mine of Colone. The Pitt or Regent diamond weighs but 136 25 carats, or 419J grains ; but is of unblemished transparency and color. It is cut in the f(jrm of a bril- liant, and its value is estimated at £125.000. The Kohinoor measured, on its arrival in Eng- land, about 1% inches in its greatest diameter, over f of an inch in thickness, and weighed 186:,' |- carats, and was cut with many facets. It has since been recut, and reduced to a dia- meter of l-,',^ by If nearly, and thus diminished over one-third in weight. It is supposed by Mr. Tennant to have been originally a dodecahedron, and he suggests that the great Russian diamond and another large slab weighing 130 carats were actudly cut from the original dode- cahedron. Tavernier gives the original weight at 787 i^ carats. The Rajah of Mattan has in his posses.-ion a diamond fronr Borneo, weighing 367 carats. The mines of Brazil were not known to alford diamonds till the commencement of the eighteenth century. 230 DESOKIPTIVE MTNERALOGT. GRAPHITi:. Plumbago. Hexagonal. In flat six-sided tables. The basal planes {O) are oftou striated parallel to the alternate edges. Cleavage : basal, perfect. Com- monly in imbedded, foliated, or granular masses. Karely in globular con- cretions, radiated in structure. H.=l-2. G.=:2-09-2-229. Lustre metallic. Streak black and shining. Color iron-black — dark steel-gi-ay. Opaque. Sectile ; soils paper. Thin laminae flexible. Feel greasy. Var. — (a) Foliated ; (b) columnar, and sometimes radiated ; (c) scaly, massive, and slaty ; (d) granular massive ; {e) earthy, amorphous, without metallic lustre except in the streak ; (/) in radiated concretions. Comp. — Pure carbon, with often a little iron sesquioxide mechanically mixed. Pyr., etc. — At a high temperature it burns without flame or smoke, leaving usually somo red oxide of iron. B.B. infusible; fused with nitre in a platinum spoon, deflagrates, con- verting the reagent into potassium carbonate, which effervesces with acids. Unaltered by acids. Diff.— See molybdenite, p. 233. Obs. — Graphite occurs in beds and imbedded masses, laminae, or scales, in granite, gneiss, mica schists, crystalline limestone. It is in some places a result of the alteration by heat of the coal of the coal formation. Sometimes met with in greenstone. It is a common furnace product. Occurs at Borrowdale in Cumberland ; in Glenstrathfarrar in Ijivemesshire ; at Arendal in Norway ; in the Urals, Siberia, Finland ; in various parts of Austria ; Prussia ; France. Large quantities are brought from the East Indies. In the United States, the mines of Sturbridge, Mass., of Ticonderoga and Fishkill, N. Y., of Brandon, Vt., and of Wake, N. 0., are worked; and that of Ashford, Conn., formerly afforded a large amount of graphite. It occurs sparingly at many other localities. The name black lead, applied to this species, is inappropriate, as it contains no laad. The name graphite, of Werner, is derived from ypdcjjw, to write. Nordenskiold makes the graphite of Ersby and Storgard monodinie. [J. SULPHIDES, TELLURIDES, SELENIDES, ARSEN- IDES, BISMUTHIDES. 1. BINARY COMPOUNDS.— Sulphides and Tellukides of the Metals OF THE SULPHUK AND AkSENIO GROUPS. REALGAR,* Monoclinic. C = 66° 5', / A /= 74° 26', Marignac, Scacchi, O A 14= 138° 21' ; c:b:d = 0-6755 : 0-6943 : 1. Habit pris- matic. Cleavage : i-l, O rather perfect ; I, i-i in 421 traces. Also granular, coarse or line ; compact. H.=l-5-2. "G. = 3-4-3-6. Lustre resinous. Color (C^^^^ o 7 aurora-red or orange-yellow. Streak varying from ^"~~^ orange-red to aurora-red. Transparent — translu- cent. Fracture conchoidal, uneven. Comp,—A8S= Sulphur 29.9. arsenic 70'1=100. Pyr., etc. — In the closed tube melts, volatilizes, and gives a transparent red sublimate ; in the open tube, sulphurous fumes, and a white crystalline sublimate of arsenous oxide. B.B. on .jharcoal burns with a blue flame, emitting arsenical and sulphurous odors. Soluble in caustia alkalies. Obs. — Occurs with ores of silver and lead, in Upper Hungary ; in Transylvania ; at Joachims- thal ; Schueeberg ; Andreasberg ; in the Binnenthal, Switzerland, in dolomite ; at Wieslooh in Baden ; near Julamerk in Koordistan ; in Vesuvian lavas, in minute crystals. ORPIMENT.* Orthorhorabic. /A 7 = 100° 40', 6> A 1-i = 126° 30', Mohs. c:b:d = 1'3511 : 1-2059 : 1. Cleavage : i-l highly perfect, i-i in traces, i-i longi- tudinally striated. Also, massive, foliated, or columnar; sometimes reni- form. H. = 1*5-2. G. = 3'48, Ilaidinger. Lustre pearly upon the faces of per- fect cleavage ; elsewhere resinous. Color several shades of lemon-yellow. Streak yellow, commonly a little paler than the color. Subtransparent — ■ Bubtranslucent. Sub-se^tile. Thin laminae obtained by cleavage flexible but not elastic. Oomp. — A82S3=Sulphur 39, arsenic 61=100. Pyr., etc. — In the closed tube, fuses, volatilizes, and gives a dark yellow sublimate ; other reactions the same as under realgar. Dissolves in nitro-hydrochloric acid and caustic alkalies. Obs — Orpiment in small crystals is imbedded in clay at Tajowa, in Upper Hungary. It is usually in foliated and fibrous masses, and in this form is found at Kapnik, at Moldawa, and at Felsobanya ; at Hall in the Tyrol it is found in gypsum ; at St. Gothard in dolomite ; at 232 DESCEIPnVE MINERALOGY. the Solfatara near Naples. Near Julamerk in Koordistan. Occurs also at Acobamhillo, Pern. Small traces are met with in Edenville, Orange Co. , N. Y. The name orpiment is a corruption of its Latin name auripig-mentum, '■'• golden painty which was given in allusion to the color, and also because the substance was supposed to con- tain gold. DiMORPniTE of Scacchi may be, according to Kenngott, a variety of orpiment. STIBNITE. Antimonite. Gray Antimony. Antimony Glance. Antimonglanz, Gernt. Orthorhombic. 422 ^ /A /= 90° 54', OM-l = 134° 16', Kreniier; c\l\d- 1-0259 : 1-0158 : 1. 6> A 1 = 124° 423 45' ; ON \-l = 134° 42^'. Lateral planes deeply striated longitudinally. Cleavage : i-i highly perfect. Often columnar, coarse or line ; also granular to impalpable. IL = 2. G. = 4-516, Haiiy. Lustre metallic. Color and streak lead- gray, inclining to steel-gray : sub- ject to blackish tarnish, sometimes iridescent. Fracture small sub-con- choidal. Sectile. Thin laminae a little iiexible. Comp.— Sb2S3=Sulphur 28 2, antimony 71 -8=100. Pyr., etc, — In the open tube sulphurous and autimonous fumes, the latter condensing as a white sublimate which B.B. is non-volatile. On charcoal fuses, spreads out, gives sulphurous and iintinionous fumes, coats the coal white; this coating treated in R.F. tinges the flame greenish-blue. Fus. =1. When pure perfectly soluble in hydrochloric acid. Diff — Distinguished by its perfect cleavage ; also by its extreme fusibility and other blow- pipe characters. Ob-. — Occurs with spathic iron in beds, but generally in veins. Often associated with blende, barite, and quartz. Met with in veins at Wolfsborg. in the Harz ; at Briiunsdorf, near Freiberg ; at Przibram ; in Hungary; at Pereta, in Tuscany; in the Urals; in Dumfriesshire; in Cornwall. Also found in different Mexican mines. Also abundant in Borneo. lu the United States, it occurs sparingly at Carmel, Me. ; at Cornish and Lyme, N. H. ; at " Soldier's Delight," Md. ; in the Humboldt mining region in Nevada ; also in the mines 'of Aurora, Esmeralda Co., Nevada. Also found in New Brunswick, 20 m. from Fredericton, S. W. side of St. John R. This Ore affords much of the antimony of commerce. The crude antimony of the shops is obtained by simple fusion, which separates the accompanying rock. From this product most, of the pharmaceutical preparations of antimony are made, and the pure metal extracted. LiviNGHTONiTE (Barccua). — Resembles stibnite in physical characters, but has a red streak, and contains, besides sulphur and antimony, 14 p. c. mercury. Huitzuco, State of Guerrero, Mexico, gee p. 430. N^ BISMUTHINITE. Bismuth Glance. Wismuthglanz, Oerm. Cleavao-e : brachvdiagonal In acicular crystals. Also Orth 3rhombic. /A / = 91° 30', Haidinger. perfect ; macrodiagonal less so ; basal ])erfect. massive, with a foliated or fibrous structure. IL=2. G. = 6-4-6-459; 7*2; 7*16, Bolivia, Forbes. Lustre metallic. iStreak and color lead-gray, inclining to tin-white, with a yellowish or irides- cent tarnish. Opaque. SULPHIDES, TELLUKroES, SELENIDES, ETC. 233 Oomp.— "81283= Sulphur 18-75, bismuth 81-25=100 ; isomorphous with stibnite. Pyr., etc. — In the open tube sulphurous fumes, and a white sublimate which B.B. fuses Into drops, brown while hot and opaque yellow on cooling. On charcoal at first gives sul- phurous fumes, then fuses with spirting, and coats the coal with yellow bismuth oxide. Fus. =1. Dissolves readily in hot nitric acid, and a white precipitate falls on diluting with water. Obs. — Found at Brandy Gill. Carrook Fells, in Cumberland ; near Redruth ; at Botallack near Land's End; at Ilerland Mine, Gwennap ; with childrenite, near CalUngton ; in Saxony; at Riddarhj'ttan, Sweden ; near Sorata, Jiolivia. Occurs in Rowan Co., N. C. , at the Earn- hardt vein ; at Haddam, Ct. ; Beaver Co., Utah. GUANAJUATITE ; F'remeUte. Fernandez, 1873; Castillo, 1873 ; Fremel, 1874. — A bismuth selenide, Bi-jSes ; sometimes with part of the selenium replaced by sulphur, that is, Bi2(Se,S)3, with Se : S = 3 : 2, which requires Selenium 23 8, sulphur G-o, bismuth 09 7 = 100. Isomor- phous with stibnite and bismuthinite {Schrauf). Guanajuato, Mexico. Silaonite from Guanajuato is BiaSe (Fernandez). See p. 438. (/ TETRADYMITE, Tellurwismuth, Oerm. Hexagonal. OaB = 118° 38', ^ A i? = 81° 2' ; c= 1-5865. Crystals often tabular. Cleavage : basal, very perfect. Also massive, foliated, or granular. H. = l'5-2. G. = 7*2-7"9. Lustre metallic, splendent. Color pale steel- gray. Not very sectile. Laminae flexible. Soils paper. Comp., Var. — Consists of bismuth and tellurium, with sometimes sulphur and selenium. If sulphur, when present, replaces part of the tellurium, the analyses for the most part afford the general formula Bi.2(Te, 8)3. Var. 1. — Fi-ee from sulphur. Bi-^Te 3= Tellurium 48-1, bismuth 51-9; G. =7-868, from Dahlonega, Jackson; 7-642, id., Balch. 2. Suljyhurous. Containing 4 or 5 p. c. sulphur. G.= 7-500, crystals from Schubkau, Wehrle. Pyr. — In the open tube a whit', sublimate of tellurous oxide, which B.B. fuses to colorless ilrops. On charcoal fuses, gives white fumes, and entirely volatilizes ; tinges the R. F. bluish- green ; coats the coal at first white (tellurous oxide), and finally orange-yellow (bismuth oxide) ; some varieties give sulphurous and selenous odors. Diflf. — Distinguished by its easy fusibility ; tendency to foliation, and high specific gravity. Obs. — Occur.s at Schubkau, near Scheinnitz ; at Retzbanya ; Orawicza; at TeUemark in Norway ; at Bastnaes mine, near Riddarhyttan, Sweden. In the United States, associated with gold ores, in Virginia ; in North Carolina, Davidson Co. , etc. Also occurs in Georgia, 4 m. E. of Dahlonega, and elsewhere ; Highland, Montana T. ; Red Cloud mine, Colorado, rare ; Montgomery mine, Arizona. JosEiTE. — A bismuth telluride, in which half the tellurium is replaced by sulphur and selenium ; Brazil. Wehklite. — Composition probably Bi(Te, S). G.=8-44. Deutsch Pilsen, Hungary. MOLYBDENITE.* Molybdiinglanz, Germ. In p\ort or tabular hexagonal prisms. Cleavage : eminent, parallel to base )f hexagonal prisms. Commonly foliated, massive, or in scales: also tine granular. I... = l-l-5, being easily impressed by the nail. G.=4-44-4-8. Lustre metallic. Color pure lead-gray. Streak similar to color, slightly inclined to green. Opaque. Lamiiise very flexible, not elastic. Sectile, and almost jualleable. liluish-gray trace on paper. 234 DESCRIPTIVE MINERALOGT. Oomp. — MoS2=Sulphur 41-0, molybdenum 5yU=lU0. Pyr., etc. — In the open tube sulphurous fumes. B.B. in the forceps infusible, impartE a yellowish-ji;Teen color to the tiame ; on charcoal the pulverized mineral gives in O. V. a strong odor of sulphur, and coats the coal with crystals of molybdic oxide, which appear yellow while hot, and white on cooling ; near the assay the coating is copper-red, and if the white coating be touched with an intermittent R. F. , it assumes a beautiful azure-blue color. Decomposed by nitric acid, leaving a white or grayish residue (molybdic oxide). Diflf.— Distinguished from graphite by its color and streak, and also by its behavior (yield- ing sulphur, etc.) before the blowpipe. Obs — Molybdenite generally occurs imbedded in, or disseminated through, granite, gneiss, zircon-syenite, granular limestone, and other crystalline rocks. Found in Sweden ; Norway ; Russia. Also in Saxony ; in Bohemia ; Rathausberg in Austria ; near Miask, Urals ; Chessy in France ; Peru ; Brazil ; Calbeck Fells, and elsewhere in Cumberland ; several of the Cornish mines; in Scotland at East Tulloch, etc. In jifdine, at Blue Hill Bay and Camdage farm. In Conn., at Haddam. In Vermont, at Newport. In iV. ILimpshire, at Westmoreland ; at Llandaflf ; at Franconia. In Mass., at Shutesbury ; at Briinfield. In JV. York, near Warwick. In Penn., in Chester, on Chestei Creek ; near Concord, Cabarrus Co., N. C. In California., at Excelsior gold mine, in Excel- uior district. In Canada, at several places. 2. BINARY COMPOUNDS.— Sulphides, Tellurides, etc., of Metals OF THE Gold, Iron, and Tm Groups. A. BASIC DIVISION". DYSCRASITE. Antimonial Silver. Antimon-Silber, Germ. Orthorhornbic. Ihl= 119° 59' ; Oh l-l 130° 41' ; c:l>:d= 1-1633: 1-73 1 5 : 1 ; 6> A 1 = 126° 40' ; Oa 1-i = 146^ 6'. Cleavage : basal distinct : 1-i also distinct ; / imperfect. Twins : stellate forms and hexagonal prisms. Prismatic planes striated vertically. Also massive, granular ; par- ticles of various sizes, weakly coherent. H. = 3-5-4. G. = 9-44-9-82. Lustre metallic. Color and streak silver- white, inclining to tin-white ; sometimes tarnished yellow or blackish. Opaque. Fracture uneven. Comp. — Ag4Sb= Antimony 22, silver 78=100. Also Ag6Sb=Antimony 15G6, silver 84-34, and other proportions. Pyr., etc. — B.B. on charcoal fuses to a globule, coating the coal with white antimonous oxide, and finally giving a globule of almost pure silver. Soluble in nitric acid, leaving anti- monous oxide. Obs. — Occurs near Wolfach in Baden, Wittichen in Suabia, and at Andreasberg ; also at Allemont in Dauphine, Casalla in Spain, and in Bolivia, S. A. ■^ DOMEYKITE. Arsenikkupfer, Germ. Reniform and botryoidal ; also massive and disseminated. H. =3-3-5. G. = 7-7-50, Portage Lake, Genth. Lustre metallic but dull on exposure. Color tin-white to steel-gray, with a yellowish to pinchbeck- brown, and, afterward, an iridescent tarnish. Fracture uneven. SULPHIDES, TELLUEroES, SELENIDES, BTO. 235 Oomp. — Cu3A3=Arseiiic 2S'3, copper 71 •7=100. Pyr., etc. — In the open tube, fuses and gives a white crystalline sablimate of arsenoua oxide. B.B. on charcoal arsenical fumes and a malleable metallic globule, which, on treat- ment with soda, gives a globule of pure copper. Not dissolved in hydrochloric acid, but soluble La nitric acid. Obs. — From the mines of Chili. In N. America, found on the Sheldon location, Portage Lake ; and at Michipicoten Island, in L. Superior. Algoponite. — Composition, CueAs^Arsenic 16 '5, copper 835. Chili ; also Lake Superior. WniTNEi ITK. — Cu9As=Arsenic 116, copper 884=100. Houghton, Mich., also California, Arizona. B. PROTO DIVISION. (a) Galenite Group. Isometric ; holohedral. ARGENTITE. Silver Glance. Vitreous Silver. Silberglanz, Oerm. Isometric. Cleavage : dodecahedral in traces. Also reticulated, arbores- cent, and filiform ; also amorphous. H. = 2-2-5. G. = 7-196-7-365. Lustre metallic. Streak and color black- ish lead-gray ; streak shining. Opaque. Fracture small sub-conchoidal, meven. Malleable. Comp.— Ago S = Sulphur 12-9, silver 87-1=100. Pyr., etc. — In the open tube gives o£E sulphurous oxide. B.B. on charcoal fuses with intu- mescence in O.F., emitting sulphurous fumes, and yielding a globule of silver. Difif. — Distinguished from other silver ores by its malleability. Obs. — Found in the Erzgebirge ; in Hungary ; in Norway, near Kongsberg ; in the Altai; in the Urals at the Blagodat mine ; in Cornwall ; in Bolivia ; Peru ; Chili ; Mexico, etc. Occurs in Nevada, at the Comstock lode, and elsewhere. Oldiiamite from the Busti meteorite is essentially CaS. Naumannite. — A silver selenide, containing also some lead. Color iron-black. From the Harz. EucAiRiTE. — A silver-copper selenide, (Cu, Ag)2Se. Color silver-white to gray. Sweden ; Chili. \^ OROOKESITR ^ Massive, compact ; no trace of crystallization. H.=2-5-3. G.=6-90. Lustre metallic. Color lead-gray. Brittle. Comp.— (Cu2,Tl,Ag) Se=Selenium 33-28, copper 45-76, thallium 17-25, silver 3-71»10C. Pyr., etc. — B.B. fuses very easily to a greenish-black shining enamel, coloring the flame strongly green. Insoluble in hydrochloric acid ; completely soluble in nitric acid. Obs. — From the mine of Skrikerum in Norway. Formerly regarded as selenide of coppei OT berzelianite. GALENITE. Galena. Bleiglanz, Oerm. Isometric ; lia^nt cubic (see f. 38, 39, etc., p. 15). Cleavage, cubic, per- fect ; octahedral in traces. Twins: twinning-plane, the octahedral plane, f . 425 (f . 263, p. 88) ; the same kind of composition repeated, f . 42G, anj 233 DESCRIPTrVE MINERALOGIf. flattened parallel to 1. Also reticulated, tabular ; coarse or fine granular ; sometimes impalpable ', occasioiiallj fibrous. 424 II. = 2'5-2'75. G.=7-25-7-7. Lustre metallic. Color and streak pure iead-p;i'ay. Surface of crystals occasionally tarnished. Fracture flat sub- elionc-lioidal, or even. Frangible. Comp., Var — PbS=Sulphur 13'4, lead 86-6=100. Contains silver, and occasionally selen- ium, zinc, cadmium, antimony, copper, as sulphides ; besides, also, sometimes native silver and gold ; all galenite is more or less argentiferous, and no external characters serve to dis- tinguish the relative amount of silver present. Pyr.— In the open tube gives sulphurous fumes. B.B. on charcoal fuses, emits sulphurous fumes, coats the coal yellow, and yields a globule of metallic lead. Soluble in nitric acid. Diflf. — Distinguished in all but the finely granular varieties by its perfect cubic cleavage. Oba. — Occurs in beds and veins, both in crystalline and uncrystalline rocks. It is often associated ^vith pyrite, marcasite, blende, chalcopyrite, arsenopyrite. etc.. in a gangue of quartz, calcite, barite. or fluorite, etc. ; also with cerussite, anglesite, and other salts of lead, which are frequent results of its alteration. It is also common with gold, and in veins of silver ores. Some prominent localities are : — Freiberg in Saxony, the Harz, Przibram and Joachimsthal, Styria ; and also Bleiberg, and the neighboring localities of Carinthia, Sula in Sweden, Leadhills and the killas of Cornwall, in veins ; Derbyshire, Cumberland, and the northern districts of England ; in Nertschinsk, East Siberia; in Algeria; near Cape of Good Hope ; in Australia ; Chili ; Bolivia, etc. Extensive deposits of this ore in the United States exist in Missouri. Dlinois. Iowa, and Wisconsin. Other important localities are : — in New York, Rossie, St. Lawrence Co. ; Wurtzboro, Sullivan Co. ; at Ancram, Columbia Co. ; in Ulster Co. In Mnine. at Lubec. In New Hampshire, at Eaton and other places. In Vermont, at Thetford. In Connecticut, at Middletown. In Massachusetts, at Newburyport, at Southampton, etc. In Pennsi/ltitnia. at Phenixville and elsewhere. In Virginia, at Austin's mines in Wythe Co., Walton's gold mine in Louisa Co., etc. In Tennessee, at Brown's Creek, and at Haysboro, near Nashville. In Michigan, in the regioii of Chocolate river, and Lake Superior copper districts, on the N. shore of L. Superior, in Neebing on Thunder Bay, and around Black Bay. In Cali- fornia, at many of the gold mines. In Nevada, abundant on Walker s river, and at Steam- boat Springs, Galena district. In Arizona, in the Castle Dome, Eureka, and other districts. In Colorada, at Pike's Peak, etc CLAUSTHALITE. Selenblei, Germ. Isometric Occurs commonly in fine granular masses ; some specimens foliated. Cleavage cubic. H.= 2-5-3. G.=7-6-8-8. Lustre metallic. Color lead-gray, somewhat bluish. Streak darker. Opaque. Fracture granular and shining. Comp., Var PbSe= Selenium 27-6, lead 73-4=100. Besides the pure selenide of lead. there are others, often arranged as distinct species, whieh contain C5obalt, copper, or mercury iu place of part of the lead, and sometimes a little silver or iron. SULPHIDES, TELLURIDES, SELENIDES, ETC. 237 Pyr. — Decrepitates in the closed tube. In the open tube gives selenous fumes and a red sublimate. B. B. on charcoal a strong' selenous odor ; partially fuses. Coats the coal near the assay at first gray, with a reddish border (selenium), and later yellow (lead oxide) ; when pure entirely volatile ; with soda gives a globule of metallic lead. Obs. — Mvich resembles a granular galenite; but the faint tinge of blue and the B.B selenium fumes serve to distinguish it. Found at Olausthal, Tilkerode, Zorge, Lehrbach, etc., in the Harz ; at Reiiisberg in Sax ony ; at the Rio Tinto mines, Spain ; Cacheuta mine, Mendoza, S. A. ZoRGiTE and Leurbacuite occur with clausthalite in the Harz. Zorgite is a lead-coppei Belenide. Lehrbachite is a lead-mercury selenide. Berzblianite. — CuoSe=Se)enium 384, copper 6r6=100. Color silver-white. From Sweden, also the Harz. Altaite, — Composition PbTe= Tellurium 38 '3, lead 61 'l?. Isometric. Color tin-white. From Savodinski in the Altai ; Stanislaus mine, Cal. ; Red Cloud mine, Colorado ; Province of Coquimbo, Chdi. TiEMANNiTE (SelenquecksUber, Oerm.). — A mercury selenide, probably HgSe. Massive. Found in the Harz ; also California. BORNITEj. Erubescite. Purple Copper Ore. Buntknpfererz, Germ. Isometric. Cleavage : octahedral in traces. Massive, structure granular or compact. II.=3. G.=:4"4—5*5. Lustre metallic. Color between copjier-red and pinelibeck-brown ; speedily tarnishes. Streak pale grayish- black, slightly shining. Fracture small conchoidal, uneven. Brittle. Comp. — For crystallized varieties FeCujSs, or sulphur 28 06, iron 1636, copper 55 •58=100. Other varieties are : FeoCu3S4, FeCusSj, and so on. The ratio of R (Cu or Fe) to S has the values 5 : 4, 4 : 3, 3 : 2, 7 : 3 (Rammelsberg), Analysis, CoUier, from Bristol, Ct. Sulphur 25-83, copper 01-79, iron 11-77, silver tr. =99-39 (R : 8=3 : 2). Pyr., etc. — In the closed tube gives a faint sublimate of sulphur. In the open tube yields sulpiiui-ous oxidt^. but gives no sublimate. B.B. on charcoal fuses in R. F. to a brittle mag- /letic globule. The roasted mineral gives with the fluxes the reactions of iron and copper, !ind with soda a metallic globule. Soluble in nitric acid with separation of sulphur. Diff.— Distinguished by its copper-red color on the fresh fracture. Obs. — Found in the mines of Cornwall ; at Ross Island in Killamey, Ireland ; at Mount Catini, Tuscany; in the Mansfeld district, Germany; and in Norway, Siberia, Silesia, and Hungary. It is the principal copper ore at some Chilian mines ; also common in Peru, Boli- via, and Mexico. At Bristol, Conn., it has been found abundantly in good crystals. Found massive at Mahoopeny, Penn., and in other parts of the same State; also at Chesterfield, Mass. ; also in New Jersey. A common ore in Canada, at the Acton and other mines. Alabandite (Manganglanz, Germ.). — MnS = Sulphur 367, manganese 63.3=100. Isomet- ric. Cleavage cubic. Color black. Streak green. From Transylvania, etc. Grunauite. — A sulphide containing nickel, bismuth, iron, cobalt, copper. From Qriinau. (J) Blende Group. Isometric ; tetiahedral. SPHALERITE or ZINC BLENDE. Black-Jack, Engl. Miners. Isometric: tetrahedral. Cleavage: dodecahedral, highly perfect. Twins twinning-plane 1, as in f. 429. Also botryoidal, and other imitative shapes ; sometimes fibrous and radiated ; also massive, compact. H.=: 3-5-4. G. = 3-9-4-2. 4-0G3, white, New Jersey. Lustre resinoua to adamanite. Color brown, yellow, black, red, green ; white or yellow 238 DESCRIPTIVE MINEEALOGY. when pui*e. Streak white — reddish-brown. Transparent —transk cent Fracture conchoidal. Brittle. 428 Comp., Var — ZnS^Sulphur 33, zinc 67=100. But often having part of the zinc replaced by iron, and sometimes by cadmium ; also containing in minute quantities, thallium, indium, and gallium. Var. 1. Ordinary. Containing little or no iron ; colors white to yellowish- brown, sometimes black ; Gr. =3 9-4'l. 2. Ferriferous; Marimttite. Containing 10 p. c. oi more of iron; dark-brown to black ; G.=3*9-4'3. The proportion of iron sulphide to zinc sulphide varies from 1 : 5 to 1 : 2. 3. Cndmiferoits ; Przibrnmite. The amount of cadmium present in any blende thus far analyzed is less than 5 per cent. Each of the above varieties may occur (^0 in crystals; {b) firm, fibrous, or columnar, at times radiated or plumose ; (c) cleavable, massive, or foliated ; (rf) granular, or compact massive. Pyr., etc. — In the open tube sulphurous fumes, and generally changes color. B.B. on charcoal, in R. F. , some varieties give at first a reddish-brown coating of cadmium oxide, and later a coating of zinc oxide, which is yellow while hot and white after cooling. With cobalt solution the zinc coating gives a green color when heated in O.F. Most varieties, after roasting, give with borax a reaction for iron. With soda on charcoal in R.F. a strong green zinc flame. Difficultly fusible. Dissolves in hydrochloric acid, during which sulphuretted hydrogen is disengaged. Some specimens phosphoresce when struck with a steel or by friction. Diff. — Generally to be distinguished by its perfect cleavage, giving angles of 60^ and 120° ; by its resinous lustre, and also by its infusibility. Obs. — Ocouts in both crystalline and sedimentary rocks, and is usually associated with galenite ; also with barite, chalcopyrite. fluorite, ."yderite, and frequently in silver mines. Derbyshire. Cumberland, and Coi'nwall, afford different varieties ; also Transylvania; Hun- gary ; the Harz; Sahla in Sweden; Ratieborzitz in Bohemia; many Saxon localities. Splendid crystals in dolomite are found in the Binnenthal. Abounds with the lead ore of Missouri, Wisconsin, Iowa, and Illinois. In N. York, Sulli- van Co.. near Wurtzboro' ; in St. Lawrence Co., at Cooper's falls, at Mineral Point; at the Ancram lead mine in Columbia Co. ; in limestone at Lockport and other places. In Moss., at Sterling ; at the Southampton lead mines; at Hatfield. In N. Hnmp., at the Eaton lead mine ; at Warren, a large vein of black blende. In Maine, at the Lubec lead mines, etc. In Conn., at Roxbury, and at Lane's mine, Monroe. In N. Jersey, a toJiite variety at Frank- lin. In Pen?!,., at the Wheatley and Perkiomen lead mines ; near Friedensville. Lehigh Co. In Virginia, at Austin's lead mines, Wythe Co. In Michigan, at Prince vein, Lake Superior. In Illinois, near Rosiclare ; near Galena, in stalactites, covered with pyrite, and galenito In Wisconsin, at Mineral Point. In Tennes.'>ee. at Haysboro', near Nashville. Named blende because, while often resembling galena, it yielded no lead, the word in Qer man meaning blind or deceiving. Sphalerite is from acpaXepoi, treacherous. A (c) Chalcocite Group. Ortborhombic. HESSITE.* Tellursilber, Oerm. Ortborhombic, and resembling chalcocite. Cleavage indistinct flive ; compact or fine grained ; rarely coarse-granular. Mas SULPnroES, TELLUEIDES, 8ELENIDES, ETO. 239 H.=2-3-5. G.=8-3-8'6. Lustre metallic. Color between lead-graj and steel-gray. Sectile. Fracture even. Comp — AgaTe=: Tellurium 37'2, silver 62-8=100. Silver sometimes replaced in part hj gold. Pyr. — In the open tube a faint white sublimate of tellurous oxide, which B.B. fuses to colorless globules. On charcoal fuses to a black globule ; this treated in R.F. presents on cooling white dendritic points of silver on its surface ; with soda gives a globule of silver. Obs — Occurs in the Altai, in Siberia, in a talcose rock ; at Nagyag in Transylvania, and at Retzbanya in Hungary ; Stanislaus mine, Calaveras Co. , Cal. ; Red Cloud mine, Colorado ; Province of Coquimbo, Chili. Petzite.— Differs from hessite in that gold replaces much of the silver. H. =2-5. G.= 8 72-8 83, Petz; 9 -0'4, Kustel. Color between steel-gray and iron-black, sometimes with pavonine tarnish. Streak iron-black. Brittle. Analysis by Genth, from Goiden Rule mine, tellurium 32-68. silver 41-8(i, gold 25-()0 = 10014. Occurs at Nagyag, Stanislaus mine, California, and several localities in Colorado. Tapalpite (Tellurwismuthsilber).— Composition (Ramm.), Ag2BiaTe2S(AgaS -I- 2BiTe). Granular. Color gray. Sierra de Tapalpa, Mexico. AOANTHTTE. / Orthorhombic. IaI= 110° 54' ; OA l-l = 124° 42', Dauber ', c : b : d = 1-4442:1-4523:1. 6> A 1-* = 135° 10' ; 6> A 1 = 119° 42'. Twins: parallel to l-l. Crystals usually slender-pointed prisms. Cleavage indis- ♦^inct. H.=2-5 or under, G, = 7'16-T'33. Lustre metallic. Color iron-black or like argentite. Fracture uneven, giving a shining surface. Sectile. Oomp. — AgoS, or like argentite. Sulphur 12'9, silver 87-1=100. P3n:. — Same as for argentite, p. 235. Obs. — Found at Joachimsthal ; also near Freiberg in Saxony. CHALCOCITE. Chalcosine. Vitreous Copper. Copper Glance. Kupferglanz, Germ. Orthorhombic. /A /= 119° 35', 6> A 1-i = 120° 57'; r : ^ : t? = 1-6676 : 1-7176 : 1 ; 0M= 117° 24' ; (9 A l-l = 135° 52'. Cleavage : /, indistinct. Twins : twinning-plane, /, producing hexagonal, or stellate forms (left half 430 431 433 433 Bristol, Ct Bristol, Ct. Bristol, Ct. of f. 432) ; also -f-l, a cruciform twin (f. 432), crossing at angles of 111° and 69° ; f. 433, a cruciform twin, having O and / of one crystal parallel respectively to i-i and O of the other. or compact and impalpable Also massive, structure granular, 'AO DESCEIPTrVE MINEEAI,OGT. H. = 2-5-3. G.—5-5-5'S. Lustre metallic. Color and streak blackibh lead-gi-ay ; often tarnished blue or green ; streak sometimes shining. Frac- ture conchoidal. Comp.— CuoS=rSTilphnr 20 2, copper 79-8=100. Pyr,, etc.— Yields nothing volatile in the closed tube. In the open tube gives off sulphur- ous fumes. B.B. on charcoal melts to a globule, which boils with spirting; with soda ia reduced to metallic copper. Soluble in nitric acid. Obs.— Cornwall affords splendid crystals. The compact and massive varieties occur in Siberia, Hesse, Saxony, the Banat, etc. ; Mt. Catini mines in Tuscany ; Mexico, Peru. Bolivia. Chili. In the United States, it has been found at Bristol, Conn., in large and brilliant crystals. In Virginia, in the United States copper mine district. Orange Co. Between Newmarket and Taney town, Maryland. In Arizona, near La Paz ; in N. W. Sonora. In Nevada, in Washoe, Humboldt, Churchill, and Nye Cos. Haruisite of Shepard, from Canton mine, Georgia, is chalcocite with the cleavage of galenite (pseudomorphous, Genth). i STROMEYERITE, Silberkupferglanz, Oerm. Orthorhombic : isomorphous with chalcocite. massive, compact. H. = 2-5-3. G. = 6-2-6-3. Lustre metallic. Streak shining. Fracture subconchoidal. /A 7=119° 35'. Also Color dark steel-gray. Comp.— AgCuS=Ag2S + Cu2S=Sulphur 15-7, silver 53-1, copper 31-2 -=100. Pyr., etc. — Fuses, but gives no sublimate in the closed tube. In the open tube sulphurous fumes. B.B. on charcoal in O.F. fuses to a semi-malleable globule, which, treated with the fluxes, reacts strongly for copper, and cupelled with lead gives a silver globule. Soluble in nitric acid. Obs.— -Found at Schlangenberg, in Siberia ; at Rudelstadt, Silesia ; also in Chili ; at Com- bavalla in Peru ; at Heintzelman mine in Arizona. Stekkbergite.*— An iron-silver sulphide, AgFe^Ss. Johanngeorgenstadt and Joachimsthol. {d) Pyrrhotite Group. Hexagonal. Rhombohedral. 484 CINNABAR. Zinnober, Oerm. Bab =92° 36', BaO = 127° 6' ; c = M448. Ac>. cording to DesCloizeaux, tetartohedral, like quartz. Also granular, massi^'e ; sometimes forming super- ficial coatings. Cleavage: /, very perfect. Twins: twinning- plane O. 11=2-2-5. G=8'99S, a cleavable variety from Neumarktel. Lustre adamantine, inclinin»r to nietal- lic when dark-colored, and to dull in fjiable varieties. Color cochineal-red, often inclining to brownish-red and lead-gray. Streak scarlet, sub transparent, opaque. Fracture subconchoidal, un- even. Sectile. jPolarizaticiu circular. Oomp — HgS (or Hg3S3)=Sulphur 13-8, mercury iron sesquioxide, bitumen. 86*2=100. Sometimes impun from clay. BULPHroES, TELLUEIDE8, SELENIDES, ETC. 241 Pyr.— In the closed tube a black sublimate. Carefully heated in the open tube gives ruI phurous fumes and metallic mercury, condensing in minute globules on the cold walls of the tube. B.B. on charcoal wholly volatile if pure. Obs.— Cinnabar occurs in beds in slate rocks and shales, and rarely in granite or poi-phyry. It has been observed in veins, with ores of iron. The most important European beds of this ore are at Almaden in Spain, and at Idria in Carniola. It occurs at Reichenau and WindiscL Kapi)el in Carinthia; in Transylvania; at Ripa in Tuscany; at Schemnitz in Hungary; in the Urals and Altai ; in China abundantly, and in Japan ; San Onofre and elsewhere in Mexico ; in Southern Peru ; forming extensive mines in California, in the coast ranges the principal mines aro at New Almaden and the vicinity, in Santa Clara Co. Also in Idaho, in limestone, abundtint. This ore is the source of the mercury of commerce, from which it is obtained by sublima tion. When pure it is identical with the manufactured vermilion of commerce. Metacinnabakite {Moore). — A black mercury sulphide (HgS). Rarely crystalliz' d H.=3. G. — 7-75. Lustre metallic. Redington mine. Lake Co., Cal. GUADALCAZARITE. — Essentially HgS, with part {i-^) of the sulphur replaced by selenium, and part of the mercury replaced by zinc (Hg : Zn=6 : 1, Petersen ; ^13 : 1, Ramm.). Massive. Color deep black. Guadalcazar, Mexico. Levigliahite is a ferruginous variety from Levigliani, Italy. MILLERITE.* Capillary Pyrites. Haarkiea ; Nickelkies, Qerm. Ehombohedral. RnR = 144'' 8', Miller, c = 0-32955. OaB = 159° 10'. Cleavage : rhombohedral, perfect. Usual in capillary crystals. Also in columnar tufted coatings, partly serai-globular and radiated. H. = 3-3-5. G. — 4*6-5-65. Lustre metallic. Color brass-yellow, inclin- ing to bronze-yellow, with often a gray iridescent tarnish. Streak bright. Brittle. Comp.— NiS=Sulphur 35 6, nickel 64-4=:100. Pyr., etc. — In the open tube sulphurous fumes. B.B. on charcoal fuses to a globule. When roasted, gives with borax and salt of phosphorus a violet bead in 0. P. , becoming gray in R.F. from reduced metallic nickel. On charcoal in R.F. the roasted mineral gives a coherent metallic mass, attractable by the magnet. Soluble in nitric acid. Obs. — Found at Joachimsthal ; Przibram ; Riechelsdorf ; Andreasberg ; several localities in Saxony ; Cornwall. Occurs at the Sterling mine, Antwerp, N. Y. ; in Lancaster Co., Pa., at the Gap mine ; with dolomite, and penetrating calcite crystals, in cavities in limestone, at St. Louis, Mo. BiiYiiicuiTE (i«eJe).— Formula Ni5S7 = Sulphur 43 -G. nickel 56-4 = 100. Color lead-gray. Occurs in radiated groups with millerite in the Westerwald. PYRRHOTITE. Magnetic Pyrites. Magnetkies, Germ. Hexagonal. O Al — 135° 8' ; c = 0-S62. Twins : twinning-plaue 1 (f. 435). Cleavage : O, perfect ; 7^ less so. Commonly .„^ massive and amorphous; structure granular. ,.i-jr!2?i H. = 3-5-4-5. G. = 4-4-4-68. Lustre metallic. Color between bronze-yellow and cop per- red, and i Bubject to speedy tarnish. Streak dark grayish- ,.£==^ black. Bi-ittle. Magnetic, being attractable in mI. due powder by a magnet, even when not affecting [j, ¥~F ^ — l*^ an ordinary needle. » ~-^^^^i::L4.^.:i__::^^ Comp.-(l) Mostly Fe,Se= Sulphur 39-5, iron 60-5=100 ; but varymgto Fe.Sg.FegSio and FoioSu. Some varieties contain 3-6 p. c. nickel. iTf^riacMe contains (Wagner) 13 p. c. Ni. Pyr., etc. — Unchanged in the closed tube. In the open tuV e gives sulphurous oxide. On 16 242 DESCRIPTIVE MINERALOCHr. charcoal in R.F. fuses to a black magnetic mass ; in O.F. is converted into iron seeqnioxidfc, which with fluxes gives only an iron reaction when pure, but many varieties yield smaU amounts of nickel and cobalt. Decomposed by muriatic acid, with evolution of sulphuretted hydrogen. Difi. — Distinguished by its magnetic character, and by its bronze color on the fresh fracture. Obs.— Occurs in Norway ; in Sweden ; at Andreasberg ; Bodenmais in Bavaria ; N. Tagilsk ; in Spain ; the lavas of Vesuvius ; Cornwall. In N. America, in Vermont, at Stafford. Corinth, and Shrewsbury ; in many parts of Massachusetts; in Connecticut, in Trumbull, in Monroe ; in N. York, near Natural Bridge in Diana, Lewis Co. ; at O'Neil mine and elsewhere in Orange Co. In N. Jersey, Morris Co., at Hurdstown. In Pennsylvania, at the Gap mine, Lancaster Co., niccoliferous. In Tennes- see, at Ducktown mines. In Canada, at St. Jerome ; Elizabethtown, Ontario (f. 435), etc. The niccoliferous pyrrhotite is the ore that affords the most of the nickel of commerce. Troilite. — According to the latest investigations of J. Lawrence Smith, composition FeS, iron proto-sulphide ; that is, iron 63 6, sulphur 36 •4=100. Occurs only in iron meteor- ites. DAUBKiiELiTE (Smith). — Composition Cr^Sa. Observed in the meteoric iron of Northern Mexico ; occurring on the borders of troilite nodules. Similar to sJiepardite^ Haidingei {—schreibernite, Shepard), described by Shepard (1846) as occurring in the Bishopville, S. C, meteoric iron. SciiREiBERSiTE also solely a meteoric mineral Contains iron, nickel, and phosphorus. WURTZITE (Spiauterite). — ZnS, like sphalerite, but hexagonal in crystallization. Bolivia. >/ GREENOCKITi;. Hexagonal ; hemimorphic. 6> A 1 = 136° 24' ; c = 0-8247. Cleavage: /, distinct; (?, imperfect. B[.=:3-3*5. G.=4'8-4-999. Lustre adamantine. Color honey-yellow; citron-yellow ; orange-yellow — veined parallel with the axis ; bi-onze- ycUovv. Streak-powder between orange-yellow and brick red. Nearly transparent. Strong double refraction. Not thermoelectric, Breithaupt. Oomp.— CdS (or Cd3S3) = Sulphur 22-2, cadium 77-8. Pjrr., etc. — In the closed tube assumes a carmine-red color while hot, fading to the original yellow on cooling. In the open tube gives sulphurous oxide. B. B. on charcoal, either alone or with soda, gives in R.F. a reddish-brown coating. Soluble in hydrochloric acid, evolving sulphuretted hydrogen. Obs. — Occurs at Bishoptown, in Renfrewshire, Scotland ; also at Przibram in Bohemia ; on sphalerite at the Ueberoth zinc mine, near Friedensville. Lehigh Co., Pa. , and at Granby, Mo. NIOOOLITE. Copper NickeL Kupfernickel, Rothnickelkiee, Germ, Hexagonal. O K\— 13°6 35'; c : 0-81944. Usually massive, structure nearly impalpable ; also reni form with a columnar structure; also reticu- lated and arborescent. H. = 5-5-5. G. = 7-33-T-671. Lustre metallic. Color pale copper-red, with a gray to blackisli tarnish. Streak pale brownish-black. Opaque. Fracture uneven. Brittle. Comp. — NiAs (or Ni3A8s)= Arsenic 56 '4, nickel 43-6=100; sometimes part of the arsenic replaced by antimony. Pyr., etc. — In the closed tube a faint white crystalline sublimate of arsenous oxide. In the open tube arsenous oxide, with a trace of sulphurous oxide, the assay becoming yellowish- green On charcoal gives arsenical fumes and fuses to a globule, which, treated with borax glass, affords, by successive oxidation, reactions for iron, cobalt, and nickel. Soluble in nitro-hydrochloric acid. Diff — Distinguished by its color from other similar sulphides, as also by its pyrognostica. SULPHIDES, TELLUKroES, BELENIDES, ETC. 243 Obs. — Occurs at several Saxon mines, also in Thuringia, Hesse, and Styria, and at AUe- inont in Dauphiny ; occasionally in Cornwall ; Chili ; abundant at Mina de la Rioja, in th6 Argentine Provinces. Found at Chatham, Conn., in gneiss, associated with smaltite. BREixnAUPTiTE. — Composition NiSb= Antimony G7'8, nickel 32 '2= 100. Color light copp(ir-red. Andreasberg. Ah ite — An antimonif erous niccolite, containing 28 p. c. Sb. Basses-Pyrenees ; WoKacb, Badea. C. DEUTO OK PYRITE DIVISION.' {a) Pyrite Group. PYRITE.* Iron Pyrites. Schwefelkies, Eisenkies, Qerm. Isometric ; pjritohedral. Tlie cube the most common form ; the pyrito- ' .edron, f. 92, p. 23, anrl related forms, f. 94, 95, 96, also very common. See also f. 103, 104, 105, p. 24. Cubic faces often striated, with striationa of adjoining faces at right angles, and due to oscillatory combination of the cube and pyritohedron, the striae having the direction of the edges between O and 2^2. Crystals sometimes acicular through elongation of cubic and other forms. Cleavage: cubic and octahedral, more or less distinct. Twins: twining-plane 7, f. 276, p. 93. Also reniform, globular, stalactitic, with a crystalline surface; sometimes radiated subfibrous. Massive. 437 438 Roseie. IT. = 6-6-5. G.=4-83-5-2. Lustre metallic, splendent to glistening. Color a pale brass-yellow, nearly uniform. Streak greenish or brownish- black. Opaque. Fracture conchoidal, uneven. Brittle. Strikes fire with Bteel. Comp., Var — FeS2=Sulphur 53-3, iron 46-7=100. Nickel, cobalt, and thallium . and also copper, sometimes replace a little of the iron, or else occur as mixtures ; and gold is some- times present, distributed invisibly through it. Pyr., etc. — In the clo.sed tube a sublimate of sulphur and a magnetic residue. B B. on charcoal gives off sulphur, burning ^vith a blue flame, leaving a residue which reacts like pyrrhotite. Insoluble in hydrochloric acid, but decomposed by nitric acid. Difif. — Distinguished from chalcopyrite by its greater hardness, since it cannot be cut with a knife ; as also by its pale color ; from marcasite by its specific gravity and color. Not malleable like gold Obs. — Pyrite occurs abundantly in rocks of all ages, from the oldest crystalline rocks to the 244 DESCRIPTIVE MINEKai^UUK. most recent alluvial deposits. It usually occurs in small cubes, also in irregular s^ihenidai nodules and in veins, in clay slate, argillaceous sandstones, the coal formation, etc. Tha Cornwall mines, Alston-Moor, Derbyshire, Fahlun in Sweden, Kongsberg in Norway. Elba, Traversella in Piedmont, Peru, are wellinown localities. Occurs in New England at many places : as the Vernon slate quarries ; Roxbury, Conn., etc. In iV. York, at llossie, at Schoharie; in Orange Co., at Warwick and Deerpark, and many other places. In Feimsyluania, at Little Britain, Lancaster Co. ; at Chester, Delaware Co, ; in Carbon, York, and Chester Cos.; at Cornwall. Lebanon Co., etc. In Wwcomin, near Mineral Point. In JV. Car., near Greensboro', Guilford Co. Auriferous pyrite is common at the mines of Colorado, and many of those of California, as well as in Virginia and the StatCi^ south. This species affords a considerable part of the iron sulphate and sulphuric acid of commerce and also much of the sulphur and alum. The auriferous variety is worked for gold in many gold regions. The name 'pyrite is derived from ttp/,, fire, and alludes to the sparks from friction. Hauehite.— Composition MnS2 = Sulphur 53-7, manganese 4(i "3 =100. Isometric. Color reddish-brown. Kalinka, Hungary. OHALOOPYRITE.* Copper Pyrites. Kupferkies, Oerm. Tetragonal ; tetrahedral. O N\-i = 135° 25'; c — 0-98550 ; 6> A 1 = 125° 40' ; 1 A 1, pyr., = 109° 53' ; 1 A 1 (f. 440) = 71° 20' and 70° 7'. Cleav- age : 2-* sometimes distinct; (9, indistinct. Twins: twinning-plane l-^ ; the plane 1 (see p. 94). Often massive. 440 H. = 3"5-4. G.=4*l-4*3. Lustre metallic. Color bi-ass-yellow ; subject to tarnish, and often iridescent. Streak greenish-black — a little shining. Opaque. Fracture conchoidal, uneven. Comp.—CuFeS2= Sulphur 34-9. copper 34 6, iron 30'5=100. Some analyses give otbet proportions ; but probably from mixture with pyrite. There are indefinite mixtures of the two, and with the increase of the latter the color becomes paler. This species, although tetragonal, is very closely isomorphous with pyrite, the variation from the cubic form being slight, the vertical axi.s being 0'98556 instead of 1. Traces of selenium have been noticed by Kersten in an ore from Reinsberg near Freiberg. Thallium is also present in some kinds, and more frequently in this ore than in pyrite. Pyr., etc. — In the closed tube decrepitates, and gives a sulphur sulilimate ; in the open tube sulphurous oxide. B.B. on charcoal gives sulphur fumes and fuses to a magnetic glo bule. The roasted ore reacts for copper and iron with the fluxes ; with soda on charunal givf.«i a globule of metallic iron with copper. Dissolves in nitric acid, excepting the sulphur, and forms a green solution ; ammonia in excess changes the green color to a deep blue. Diff, — Distinguished from pyrite by its inferior hardness, it can be easily scratched with tlie knife ; and by its deeper color. Not malleable like gold, from which it differs also in being decomposed by nitric acid. SULPHIDES, TELLUEIDES, SELENTDES, ETC. 245 Obs. — Chalcopyrite is the principal ore of copper at the Cornwall miaes. Occurs at Frei- berg; in the Bannat ; Hungary; and Thuringia ; in Scotland ; in Tuscany; in South Australia ; in tin ft crystals at Oerro Blanco, Chili. A common mineral in America, some localities are : Stafford, Vt. ; Rossie, Ellenville, N. T.; Pheuixville. etc., Perm. The mines in North Carolina and eastern Tennessee afford large quantities. Occurs in Cal. . in different mines along a belt between Mariposa Co. and Del Norte Co., on west side of, and parallel to, the chief gold belt; occurring massive in Calaveras Co.; in Mariposa Co., etc. In Canada, in Perth and near Sherbrooke; extensively mined at Bruce mines, on Lake Huron. Named from xa^f »s, brass, and pyrites, by Henckel, who observes in his Pyritology (1725) thrit chalcopyrite is a good distinctive name for the ore. CUBANiTE is CuFe.Sj, or CuFcoSs (Scheidhauer). — Occurs massire at Barracanao, Cuba; Tunaberg, Sweden. Barnhardtite, from North Carolina. — Composition uncertain, perhaps CujFesSe. It may be partly altered from chalcopyrite. Stannite (Zinnkies, Germ.). — A sulphide containing 26 p. c. tin; also copper, iron, and rina Massive, Color steel-gray. Chiefly from Cornwall, also Ziunwald. LINNJBITE. Kobaltnickelkies, Germ. Isometric. Cleavage : cubic, imperfect. Twins : twinniiig-plane octa- hedral. Also massive, granular to compact. 1I.=5"5, G.=4"8-5. Lustre metallic. Color pale steel-gray, tarnishing copper-red. Streak blackish-graj. Fracture uneven or subconchoidal. Comp— CosSi (or 2CoS+CoSo)= Sulphur 420, cobalt 580=100; but having the cobalt replaced partly by nickel or copper, the proportions varying very much. The Miisen ore {siege/lite) contains 30-40 p. c. of nickel. Pyr., etc — The variety from Musen gives, in the closed tube, a sulphur sublimate ; in the open tube, sulphurous fumes, with a faint sublimate of arsenous oxide. B.B. on charcoal gives arsenical and sulphurous odors, and fuses to a magnetic globule. The roasted mineral gives with the fluxes reactions for nickel, cobalt, and iron. Soluble in nitric acid, with separa- tion of sulphur. Difif, — Distinguished by its color, and isometric crj'stallization. Obs,- -In gneiss, at Bastnaes, Sweden; at Miisen, near Siegen, in Prussia; at Siegen (sicgenite), in octahedrons; at Mine la Motte, in Missouri, mostly massive, also crystalline • and at Mineral HiU, in Maryland. SMALTITE.* Speiskobalt, Geim, Isometi'ic. Cleavage : octahedral, distinct ; cnbic, in traces. Also mas- sive and in reticulated and other imitative shapes. H. = 5-5-6. G. = 6-4to7'2. Lustre metallic. Color tin-white, inclining, when massive, to steel-gray, sometimes iridescent, or grayish from tarnish. Streak grayish-black. Fracture granular and uneven. Brittle. Comp., Var. — For typical kind (Co,Fe,Ni)A3.=: (if Co, Fe, and Ni be present in equal parts) Arsenic 72"1, cobalt 9 4, nickel 95, iron 9"0=100. It is probable that nickel is nevei wholly absent, although not detected in some of the earlier analyses ; and in some kinds it is the principal metal. The proportions of cobalt, nickel, and iron vary much. The following analyses will serve as examples of the different varieties : As 1. Schneeberg 70-37 2. Allemont {chloa7ithite) 7 \ -11 3. Kiechelsdorf 60 42 i. Schneeberg 74 80 Co Ni Fe Cu 13-95 1-79 11-71 1-39 SO-66, Bi 0-01 =99-88 Hofmann 18-71 6-82 S 2-29=98-93 Rammelsberg. 10-80 25-87 0-80 8 2-11 = 100. 8-79 13-86 7-33 S 0-85=99-63 Karstedt 246 DESCRIPTIVE MINERALOGT. P3rr., etc. — In the close tube gives a sublimate of metallic arsenic ; in the open tube 3 white sublimate of arsenous oxide, and sometimes traces of sulphurous oxide. B.B. on char- coal gives an arsenical odor, and fuses to a globule, which, treated with successive portions of borax-glass, affords reactions for iron, cobalt, and nickel. Obs. — Usually occurs in veins, accompanying ores of cobalt or nickel, and ores of silvei and copper ; also, in some instances, with niccolite and arsenopyrite ; often having a coating of annabergite. Occurs at Schneeberg, etc., in Saxony ; at Joachimsthal ; also at Wheal Spamon in Corn- wall ; at Riechelsdorf in Hesse ; at Tunaberg in Sweden ; AUemont in Dauphine. Al&a in crystals at Mine La Motte, Missouri. At Chatham, Conn., the chloanthibe {cluithamite) occurs in mica slate, associated generally with arsenopyrite and sometimes with niccolite. SPATnioPYRiTE is closely allied to smaltite, with which it occurs at Bieber in Hessen. Skuttehudite (Tesseralkies, Germ.). — CoAs3=Arsenic79'2, cobalt20 8=100. Isometric. Skutterud, Norway. COBALTITE. Glance Cobalt. Kobaltglanz, Germ. Isometric ; pjritohedral. Commonly in pyritohedrons (f. 92, 95, etc., p. 23). Cleavage : cubic, perfect. Planes O striated. Also massive, granular or compact. H. = 5-5. G. = 6-6*3. Lustre metallic. Color silver- white, inclined to red ; also steel-gray, with a violet tinge, or grayish-black when containing mnch iron. Streak grayish-black. ' Fracture uneven and lamellar. Brittle. Comp., Var.— CoAsS (or CoS3-|-CoAs,)=Su]phur 19-3, arsenic 45-2, cobalt 35-5=100. The cobalt is sometimes largely replaced by iron, and sparingly by copper. Pyr., etc. — Unaltered in the closed tube. In the open tube, gives sulphurous fumes and a crystalline sublimate of arsenous oxide. B.B. on charcoal gives off sulphur and arsenic, and fuses to a magnetic globule ; with borax a cobalt-blue color. Soluble in warm nitric acid, separating arsenous oxide and sulphur. Diff.— Distinguished by its reddish-white color; also by its pyritohedral form. Obs. — Occurs at Tunaberg, Hokansbo, in Sweden ; also at Skutterud in Norway. Other localities are at Querbach in Silesia, Siegen in Westphalia, and Botallack mine, in Cornwall. The most productive mines are those of Vena in Sweden. This species and smaltite afford the greater part of the smalt of commerce. It is also employed in porcelain painting. GERSDORFFITE. Nickelarsenikkies, Arseniknickelglanz, Oerm. Isometric ; pyritohedral. Cleavage : cubic, rather perfect. Also lamel- lar and granular massive. H.=5-5. G.=5.6-6*9. Lustre metallic. Color silver-white — steel- gray, often tarnished gray or grayish-black. Streak grayish-black. Fj"ac- ture uneven. Comp,, Var — Normal, NiAsS (or NiSs+NiAsi)^ Arsenic 45 "5, sulphur 19"4, nickel 35-l=: 100. The composition varies in atomic proportions rather widely. Pyr., etc. — In the closed tube decrepitates, and gives a yellowish-brown sublimate of arsenic sulphide. In the open tube yields sulphurous fumes, and a white sublimate of ar.sen- ous oxide. B.B. on charcoal gives sulphurous and garlic odors and fuses to a globule, which, with borax-glass, gives at first an iron reaction, and, by treatment with fresh portions of the flux, cobalt and nickel are successively oxidized. Decomposed by nitric acid, forming a green solution, with reparation of sulphur and arsen- ous oxide. Obs. — Occurs at Loos in Sweden ; in the Harz ; at Schladming in Styria ; Kamsdorf in Lower Thuriugia ; Haueisen, Voigtiand ; near Ems. Also found as an incrustation u( Phenixville, Pa. SULPHroES, TELLUEroES, SELENIDES, ETC. 247 TTllmannite.— NiSbS (NiSo+NiSb2)=Antimony 57-2, sulphur 15-1, nickel 27 •7=100 Generally contains also some arsenic. Color steel-g^ay. Siegen, Harzgerode, etc. CouYNiTE. — Ni(As,Sb)S, but the arsenic (38 p. c. ) in excess of the antimony. Olsa, Corin- thia. Woi.FAcniTE (Petersen), from Wolfach, Baden, is similar in composition, bub ia orthorhombic in form. Lauuite. — An Dsmium-ruthenium sulphide. Analysis (Wohler) Sulphur 31 "79 [Osmium 3 '03], Ruthenium G5. 18=100. Occurs in minute octahedrons from the platinum-washt^a of Borneo ; as also those in Oregon. (J) Marcasite Group. Orthorhombic. MAROASITE. White Iron Pyrites. Strahlkies, etc., Germ. Orthorhombic. I^I= 106° 5', (9 A l-l = 122° 26', Miller ; c:l:d=. 1-5737 : 1-3287 : 1. 0M = 116° 55' ; O M-l = 130° 10'. Cleavage: /rather perfect; l-i 442 in traces. Twins: t\'S!3iining-plane 7, sometimes consisting of live individnals (sec f. 308, p. 98) ; also \-l. Also globular, reniform, and other imitative shapes — structure straight columnar ; often tnassive, columnar, or granular. II. :=6-G 5. G.=4'678-4:-847. Lustre metallic. Color pale bronze-yel- low, sometimes inclined to green or gray. Streak grayish- or brownish- black. P''racture uneven. J3rittle, Comp., Var,— FeS2, like pyrite=Sulphur 53 3, iron 46-7=100. The varieties that have been recognized depend mainly on state of crystallization ; as the Radiated {Strahlkies) : Radiated; also the simple crystals. Cockscomb {Kammkies) : Aggre- gations of flattened crystals into crest-like forms. Spear {Speerkies) : Twin crystals, with reentering angles a little like the head of a spear in form. Capillary (Haarkies) : In capil- lary crystallizations, etc. Fyr. — Like pyrite. Very liable to decomposition ; more so than pyrite. Diflf. — Distinguished from pyrite by its paler color, especially marked on a fresh surface ; by its tendency to tarnish ; by its inferior specific gravity. Obs, — Occurs near Carlsbad in Bohemia ; at Joachimsthal, and in several parts of Saxony ; in Derbyshire ; near Alston Moor in Cumberland ; near Tavistock in Devonshire, and in Cornwall. At Warwick, N. Y. Massive fibrous varieties abound throughout the mica slate of New England, particularly at Cummington, Mass. Occurs at Lane's mine, in Monroe, Conn. ; in Tnambull ; at East Haddam ; at Haverhill, N. H. ; Galena, III, in stalactites. In Canada in Neebing. Marcasite is employed in the manufacture of sulphur, sulphuric acid, and iron sulphate, though less frequently than pyrite. ARSENOPYRITE, or MISPICKEL. Arsenical Pyrites. Arsenikkies, Germ. Orthorhombic. 7 A /= 111° 53', Oa1-1 = 119° B7';c:b:d = 1-7588 : 14793 :1. (9a1 = 115° 12', 6>Al-« = 130° 4'. Cleavage: /rather distinct ; O, faint traces. Twins : twinning-plane /, and ] -l. Also colum- nar, straight and divergent ; granular, or compact. li.=5-o-6. G. =60-6-4; 6-269, Franconia, Kenngott. Lustre metallio; 248 DESCRIPTIVE MINERALOGY. Color silver-wliite, inclining to steel-gray. Streak dark graj'ish-black. Frao tnre uneven. Brittle. 448 444 445 Franconia, N. H. Franconia, N. H., and Kent, N, Y. Danaite. Oomp., Var.— FeA8S=FeSa+FeAso=Arsenic46-0, sulphur 19-6, iron 34-4=100. Part of the iron sometimes replaced by cobalt ; a little nickel, bismuth, or silver are also occasionally present. The cobaltic variety, called danaite (after J. Freeman Dana), contains 4-10 p. c. of cobalt. Pyr., etc. — In the closed tube at first gives a red sublimate of arsenic sulphide, then a black lustrous sublimate of metallic arsenic. In the open tube gives sulphurous fumes and a white sublimate of arsenous oxide. B.B. on charcoal gives the odor of arsenic. The varieties containing cobalt give a blue color with borax-glass when fused in O.F. with successive por- tions of flux until all the iron is oxidized. Gives fire with steel, emitting an alliaceous odor. Decomposed by nitric acid with separation of arsenous oxide and sulphur. Diff. — Distinguished by its form from smaltite. Leucopyrite (lollingite) do not give decided sulphur reactions. Obs. — Found principally in crystalline rocks, and its usual mineral associates are ores of silver, lead, and tin ; pyrite, chalcopyrite, and spalerite. Occurs also in serpentine. Abundant at Freiberg ; at Reichenstein in Silesia ; at Schladming ; Andreasberg ; Joachims- thal ; at Tunaberg in Sweden ; at Skutterud in Norway ; in Cornwall ; in Devonshire at the Tamar mines. In New Ilnmpshk'e, in gneiss, at Franconia {danaite) ; also at Jackson and at Haverhill. In Maine, at Blue Hill, Corinna, etc. In Vermont, at Brookfield, Waterbury, and Stockbridge. In Ma-ss., at Worcester and Sterling. In Conn., at Monroe, at Mine Hill, Roxbury. In JVcw Jersep, at Franklin. In N.York, massive, in Lewis, Es.sex Co., near Edenville, and else- where in Orange Co. ; in Carmel ; in Kent, Putnam Co. In California, Nevada Co., Grass valley. In S. America, in Bolivia ; also, niccoUferons var., between La Pas and Yungas in Bolivia (anal, by Kroeber). Lollingite is FeAs, (=Ar8enic 72"8, iron 27 '2^ and Leucopyrite is FcjAss (=Arsenic 66"«, iron 33*3). They are both like arsenopyrite in form. Found, the former at Lolling ; Schladming ; Satersbeig, near Fossum, Norway ; the latter at Reichenstein ; Geyer (geyerite) near Hiittenberg, Carinthia. Glaucodot (Co,Fe)S3-t-(Co,Fe)A83, with Co : Fe=2 : 1 = Sulphur 19 '4, arsenic 45 -5, cobalt 23 8, iron 113 = 1()0. Form like arsenopyrite. Huasco, Chili; Hakansbo, Sweden. ALL0CLA8ITB R4(As,Bi)7So, with R=Bi,Co,Ni,Fe,Zn. Orawicza, Hungary. A SYLVANITE. Graphic Tellurium. Schrifterz, Schrift-Tellur, Oerm. Monoclinic. C= 55° 21f , /A 1= 94° 26', OM-t= 121° 21' ; c'.b: a = 1*7732 : 0-889 : 1, Kokscharof. Cleavage: i-l distinct. Also massive; imperfectly columnar to granular. H.=l*5-2. G. = 7-99-8-33. Lustre metallic. Streak and color pure steel- gray to silver-white, and sometimes nearly brass-yellow. Fracture unevea Oomp., Var.— (Ag,Au)Tea = (if Ag : Au=l : 1) Tellurium 55-8, gold 28-5, silver 15-7=100 iUitimoDy sometimes replaces part of the tellurium, and lead part of the other metals. 8ULPHAR8ENITE8, SULPHANTIMONTTES, ETC. 219 Pyr., etc. — In the open tube gives a white sublimate which near the assay is gray ; when treated with the blowpipe flame the sublimate fuses to clear transparent drops. B.B. on charcoal fuses to a dark gray globule, covering the coal with a white coating, which treated in R.F. disappears, giving a bluish-green color to the flame; after long blowing a yellow, malleable metallic globule is obtained. Most varieties give a faint coating of the oxides oi lead and antimony on charcoal. Obs. — Occurs at Offenbanya and Nagyag in Transylvania. In California, Calaveras Co., at the Meloues and Stanislaus mines ; Red Cloud mine, Colorado. Nam«d from Transylvania, the country in which it occurs, and in allusion to sylvanium, one of the names at first proposed for the metal tellurium. Called graphic because of a resem- blance in the arrangement of the crystals to writing characters. Schrauf has stated that, according to his measurements, sylvanite is orthorJivmbic. Calaveuite [Geiith.) has the composition AuTei = Tellurium 555, gold 44-5=100. Mas- Bive. Color bronze-yellow. Stanislaus mine, Cal. ; Red Cloud mine, Colorado. NAQYAGITE.* Blattererz, BlatterteUur, Germ. Tetragonal. A l-^ = 127° 37' ; c = 1-29S. 6> A 1 = 118° 37'. Cleav- age: basal. Also gramilarly massive, particles of various sizes ; generally foliated. 446 H.:=l-l-5. G.=6-S5-7-2. Lustre metallic, splen- dent. Streak and color blackish lead-gra}'. Opaque. Sectile. Flexible in thin laminae. Comp. — Uncertain, perhaps R(S,Te)3, withR=Pb,Au (Ramm.). Analysis, Schonlein, Te 80-52, S 8-07, Pb 50-78, Au 911, Ag 0-63, Cu 0-99 = 100. Pyr., etc. — In the open tube gives, near the assay, a grayish sublimate of antimonate and tellurate, with perhaps some sulphate of lead ; farther up the tube the sublimate consists of antimonous oxide, which volatilizes when treated with the flame, and tellurous oxide, which at a high temperature fuses into colorless drops. B.B. on charcoal forms two coatings : one white and volatile, consisting of a mixture of antimonite, tellurite, and sulphate of lead ; and the other yellow, less volatile, of oxide of lead quite near the assay. If the mineral is treated for some time in 0. F. a malleable globule of gold remains ; this cupelled with a little assay le-ad assumes a pure gold color. Decomposed by nitro-hydrochloric acid. Obs. — At Nagyag and Offenbanya in Transylvania, in foliated masses and crystalline plates. I" CovELLiTE (Kupferindig, Germ.). — Composition CuS=Sulphur 33-5, copper 005 = 100. Hexagonal. Commonly massive. Color indigo-blue. Mansfeld, etc. ; Vesuvius, on lava ; Chili. Melonite {Genth.). — A nickel telluride, formula probably Ni2Tes=tellurium 76-5, nickel 23-5=100. Hexagonal. Cleavage basal eminent. Color reddish-white. Streak dark-gray. Occurs mixed with other tellurium minerals at the Stanislaus mine, Cal. 3. TERNARY COMPOUNDS. Sulpharsenites, Sulphantimonites, SULPHOBISMUTIIITES.* {a) Group I. Formula R(As,Sb)2S4=RS + (As,Sb)2S8. MIARGYRITZ3. Monoclinic, C= 48° 14'; /a/=: 106° 31', OM-l- 13G° 8' ; c:h'.d = 1*2883 : 0'9991 : 1, Naumann. Crystals thick tabular, or stout, or^hort prismatic, pyramidal. Lateral planes deeply striated. Cleavage'?^^, 1-i imperfect. * The species of this group contain as bases chiefly copper, lead, and silver. They can bo most readily distinguished by their behavior before the blowpipe. Attention may be called to the group of lead sulphantimonites, sinkentte, plnginnite, {jdine^onite) botdangcrite, rnene- 'jhintte, geocroni e. for which the pyrognoetics are nearly similar, and which are most aurelf •*^«tinguished by their specific gravity. 250 DESCKIPnVE MINEEAiOGT. H.=2-2'5. G.=5'2-5'4. Lustre snbmetallic-adainantine. Color iron black. Streak dark cherry-red. Opaque, except in thin splinters, w'lich, by transmitted light, are deep blood-red. Fracture subconclioidal. Comp.— AgSbSa (or AgoS+SbsS3)=Sulphur 21-8, antimony 41-5, silver 367=100. Pyr., etc. — In the closed tube decrepitates, fuses easily, and gives a sublimate of antimony sulphide ; in the open tube sulphurous and antimonoue fumes, the latter as a white sublimate. B.B. on charcoal fuses quietly, with emission of sulphur and antimony fumes, to a gray bead, which after continued treatment in O.F. leaves a bright globule of silver. If f]\9. silver globule be treated with phosphorus salt in O.F., the green glass thus obtained shows traces of coppei when fused with tin in R. F. Decomposed by nitric acid, with separation of sulphur and antimonous oxide. Obs. — At Braiinsdorf , near Freiberg in Saxony ; Felsobanya {kenngottite) ; Przibram in Bohemia ; Clausthal {Jiypargyrite) ; Guadalajara in Spain ; at Parenos, and the mine Sta. M. de Catorce, near Potosi ; also at Molinares, Mexico. SARTORITE. SCLKKOCLASE. Orthorhombic. 7 A /= 123° 21', 6> A 1-* = 131" 3' ; c:l'.d = 1-1483 : 1*8553 : 1. Crystals slender. Cleavage : 447 O quite distinct. H.=3. G.= 5-393. Lustre metallic. Color dark lead-gray. Streak reddish- brown. Opaque. Brittle. Oomp — PbA8oS4(PbS+A.s,S,)=Sulphur 26-4, arsenic 30 9, lead 42-7=100. Pyr., etc. — Nearly the same as for dufrenoy- site (q. v.), but differing in strong decrepitation, Obs.— From the Binnen valley with dufrenoy- site and binnite. As the name Scleroclase ia inapplicable, and the mineral was first an- nounced by Sartorius v. Waltershausen, the species may be appropriately called Sartorite. It is the binnite of Heusser. ZINEENTTE. Orthorhombic. /A/=120°39', Rose. Usual in twins, as hexagonal prisms, with a low hexagonal pyramid at summit. Lateral faces longitudi- nally striated. Sometimes columnar, fibrous, or massive. Cleavage not distinct. H.= 3-3-5. G.= 5-30-5-35. Lustre metallic. Color and streak steel- gray. Opaque. Fracture slightly uneven. Comp.— PbSbnS, (or PbS+SboS3)=Sulphur 22-1, antimony 422, lead 35-7=100. Pyr., etc. — Decrepitates and fuses very easily ; in the closed tube gives a faint sublimate of sulphur and antimonous sulphide ; in the open tube sulphurous fumes and a white subli- mate of oxide of antimony. B. B. on charcoal is almost entirely volatilized, giving a coating which on the outer edge is white, and near the assay dark-yellow; with soda in R.F. yields globules of lead. Soluble in hot hydrochloric acid with evolution of sulphuretted hydrogen and separation of lead chloride on cooling. Resembles stibnite and boumonite, but may be distinguished by its superior hardness and specific gravity. Obs. — Occurs at Wolfsberg in the Harz. CnALCOsTiBtTE (Kupferantimonglanz, Oerm.). — Composition CuSbS, (or CuoS f Sb.;Sj)-- Sulphur 257, antimony 48*9, «opper 25 '4. Color lead -gray to iron-gray. Wolfsberg in the Ilarz. Empi,ectite (Kupferwismuthglanz, Oerm.). — Composition CuBiSj (or Cu,S+BioS3)=Sul. phur 19 "1, bismuth 62-0, copper 18*9=1(K). Color grayish to tin-white. Schwarzenberg, Btxony; Copiapo, Chilu SULPHAESENITESj SULPHANnMONITES, ETC. 251 Berthierite.— Composition approximately FeSbaSi (orPeS+Sb.2S3)=SulFhur30-0, anti- mony 57-0, iron 130=100. Color dark steel-gray. Auvergne ; Braunsdorf, Saxony ; Corn- wall, etc. ; San Antonio, Cal. (b) Sub-Group. Formula K3(A.s,Sb,Bi)4S9=3PvS+2(A8,Sb,Bi)2S3. V' Plagionite.— Composition (Rose) PbjSbeSis (or 4PbS + 3Sb2S3) = Sulphur 21-1, antimony 37 0, lead 4'l O. Monoclinic. G. =5 '4. Found at Wolfsberg in the Harz. JoRDANiTE (v. Rath).— Composition Pb3A84S9 (or 3PbS+2Ae2S3) = Sulphur 23-8, arsenic 24-8, lead 51 -4. Orthorhombic. Resembles sartorite, but distinguished by its black streak, its six-sided twins, and by not decrepitating B.B. Binnenthal, Switzerland. BiNNiTii.— Composition probably CueAsjSg (or 3Cu2S + 2As.S3) = Sulphur 29*7, arsenic 31 '0, copper 39-3=100. Isometric. Streak cherry-red. Binnenihal'm dolomite {dufrenoi/site oi V. Waltershausen). Klaprotholite [Petersen). — Composition CueBijSba (or 3Cu.,S+2Bi3S3). Orthorhombic. Cleavage i-l distinct. Color steel-gray. G.=4*6. Wittichen, Baden. SCHIRMERITE ( CrV??«/i).— Composition RsBiiSg (or 3RS-l-2Bi2S3), with R=Ag2 : Pb=2 : 1. This requires sulphur 1(5-4. bismuth 473, silver 24 5. lead 11-8=100. Massive, disseminated in quartz. Color lead-gray. Red Cloud mine, Colorado. (c) Gkoup II. Formula Il,(Sb,A8)2S5=2KS + (Sb,As)2S3. JAMESONITE. Federerz, Germ. Orthorhombic. /A /= 101° 20' and 78° 40'. Cleavage basal, highly perfect; /and i-i less perfect. Usually in acicular crystals. Also fibrous massive, parallel or divergent ; also in capillary forms ; also amorphous massive. H.=2-3. G.=5*5-5'8. Color steel-gray to dark lead-gray. Streak gray. Comp.— PbgSb.Ss (or 2PbS-fSb2S3) ; more strictly 2PbS=2 (or Pb,Fe)S. If Fe : Pb=l : 4, Sulphur 21-1, antimony 32-2, lead 43-7, iron 30=100. Small quantities of zinc, bis- muth, silver, and copper are also sometimes present. Pyr. — Same as for zinkenite. Diff. — Distinguished from other related species by its perfect basal cleavage. Obs. — Ja inenonite occnis principally in Cornwall, in Siberia, Hungary, at Valentia, d'Alcan- tara in Spain, and BrazU. The feather oi'e occurs at Wolfsberg in the Eastern Harz ; also at Andreasberg and Clans- thai ; at Freiberg and Schemnitz ; at PfafiEenberg and Meiseberg ; in Tuscany, near Bottino ; at Chonta in Peru. 121° 30', c:l\d = 1-631S : 448 DUFRENOYSITE. Orthorhombic. I^ /= 93° 39', O A 14 1*0658 : 1. Usual in thick rectan- gular tables. Cleavage: perfect. Also massive. II. = 3. G.=5-o49-5-569. Lustre metallic. Color blackish lead-giay. Streak reddish-brown. Opaque. .Brit- tle. Oomp.— Pb2As2S6 (or 2PbS+2A8,S,)=Sul- phur 22-10, arsenic 20-72, lead 57-18=100. Pyr., etc. — Easily fuses and gives a subli- mate of sulphur and arsenous sulphide ; in the open tube a smell of sulphur only, with a sublimate of sulphur in upper part of tube, and y 252 DESCEIPTIVE MINERALOGT. of araenous oxide below. On charcoa* decrepitates, meltE, yields fumes of arsenic and s globule of lead, which on cupellation yields silver. Obs. — From the Binnenthal in the Alps, in crystalline dolomite, along with sartoiite, Jordan* ite, binnite, etc. Damour, who first studied the arsenio-sulphides of the Binnenthal, analyzed the massive ore and named it dvfrenoysite. He inferred that the crystallization was isometric from soma associated crystals, and so published it. This led von Waltershausen and Heusser to call the isometric mineral dufrenoysite, and the latter to na ne the orthorhombic species binnite. Vou Waltersliausen, after studying the prismatic mineral, made out of the species arsenomeUin and scleroclnse, yet partly on hypothetical grounds. Recently it has been found that three ortho- rhombic minerals exist at the locality, as announced by vom Rath, who identifies one, by speci- fic gravity and composition, with Damour's dvfreiwysite ; another he makes scle/vclose of von Waltershausen (sartorite, p. 250) ; and the other he names jordanite (p. 251). The isometric mineral was called binnite by DesCloizeaux. 449 FREIESLEBENITE. Schilfglaserz, Oerm. Monoclinic. C = 87° 46', /A /= 119° 12', OM-l= 137° 10' (B. & M.) ; c\h\d — 1-5802 : 1-7032 : 1. 6* A l-i = 123° 55'. Prisms lonoitudiuallj striated. Cleavage : / perfect.' li. = 2-2-5. G. = 6-G-4. Lustre metallic. Color and streak light steel-gray, inclining to silver-white, also blackish lead-gray. Yields easily to the knife, and is rather brittle. Fracture subconchoidal — uneven. Comp — Pb.AgsSbaSp. Ramm. (or TRS+SSboSj, with7RS=4PbS -h3Ag2S) = Sulphur IHS, antimony 209, lead 80-5, silver 23 -8 = 100. Pyr. — In the open tube gives sulphurous and antimonial fumes, the latter condensing as a white sublimate. B. B. on charcoal fuses easilj'', giving a coating on the outer edge white, from antimonoua oxide, and near the assay yellow, from oxide of lead ; continued blowing leaves a globule of silver. Obs. — Occurs at Freiberg in Saxony and Kapnik in Transylvania; at Ratieborzitz ; at Przibram ; at Felsbbanya; at Hieudelencina iu Spain. According to v. Zepharovich, the mineral from Przibram and Braunsdorf, and part of that from Freiberg, while identical in composition with freies- lebenite, has an orthorhombic form. It is called by him diapdokite. Bromgniardite. — Composition AgjPbSbiSe (or PbS-fAg,,S-fSb2S3) = Sulphur 19-4. anti- mony 29-5, silver 2G-1, lead 250=100. Isometric; in octahedrons, also massive. Color gray- ish-black. Mexico. CosALiTE ( (?e/ii;/i).— Composition PbjBijSs (or 2PbS-}-Bi2S3)=Sulphur lG-1. bismuth 42-2, lead 41-7=100. Color lead-gray. Soft and brittle. Cosala, Sinaloa, Mexico. Identical (Frenzel) with Hermann's retzbanyite. Pyrostilpnitk (Feuerblende, Germ.). — In delicate crystals; coloit hyacinth-red. Con- tains G2-3 p. c. silver, also sulphur and antimony. Freiberg ; Andreasberg; Przibram. RiTTiNGERiTE. — In minute tabular crystals. Color black. Streak orange-yellow. Con* tains sulphur, antimony, and silver. Joachimsthal. {d) Gkoup III. Formula UlK%,^h)S6= 3RS 4- (A8,Sb)2S3. PrRARGYRITE. Ruby SUver. Dark Red Silver Ore. Dunklea Rothgiiltigerz, Germ. Hhombohedral. "Opposite extremities of crystals often unlike. li A Ji = 108° 42' (B. & M.) ; OaR = 137° 42' ; c = 0-788. (9 A !» = 112° 33', 6>A1"=100° 14', ^Ai = 144° 21'. Cleavage: E rather imperfect. RULPHARSKNTTES, SULPHANTIMONITESj ETC. 253 450 45t Tmns: composition-face— I; 6? or basal plane, as in f. 290, p. 95; also It and /. Also massive, structure granular, sometimes impalpable. H. = 2-2-5. G.=5-7-5-9. Lustre metallic-adamantine. Color black, sometimes approaching cochineal-red. Streak cochineal-red. Translucent — opaque. Fracture conchoidal. Oomp. — AgsSbSa (or 3AgoS-fSb2S3)=Sul- phur 17-7, antimony 22-5, silver 59-8=100. Pyr., etc. — In the closed tube fuses and gives a reddish sublimate of antimonous sulphide ; in the open tube sulphurous fumes and a white sublimate of antimonous oxide. B. B. on charcoal fuses with spirting to a globule, gives off antimonous sulphide, coats the coal white, and the assay is converted into silver sulphide, which, treated in O.F. , or with soda in R.F., gives a globule of fine silver. In case arsenic is present it may be detected by fusing the pulverized mineral with soda on charcoal in R. F. Decomposed by nitric acid with separation of sulphur and antimonous oxide. Obs. — Occurs principally with calcite, native arsenic and galenite, at Andreasberg ; also in Saxony, Hungary, Norway, at Gaudalcanal in Spain, and in Cornwall. In Mexico abundant. In Chili ; in Nevada, at Washoe in Daney Mine ; abundant about Austin, Eeesie river ; at Poor Man lode. Idaho. PROUSTITE. Light Red Silver Ore. Lichtes Eothgiiltigerz, Oerm. Khombohedral. RnR = 107° 48', OkR = 137° 9' ; c = 0-78506, Also granular massive. IL = 2-2-5. G. = 5-422-5"56. Lustre adamantine. Color cochineal-red. Streak cochineal-red, sometimes inclined to aurora-red. Subtrausparent- subtranslucent. Fracture conchoidal — uneven. Comp — AgaAsSs (or 3Ag-.S-t-As,.S3)=Sulphur 19-4, arsenic 15"1, silver 65 5 = 100. Pyr., e^.c — In the closed tube fuses easily, and gives a faint sublimate of arsenous sulphide ; in the open tube sulphurous fumes and a white crystalline sublimate of arsenous oxide. B.B. on charcoal fuses and emits odors of sulphur and arsenic ; by prolonged heating in O.F., oi with soda in R.F.. gives a globule of pure silver. Some varieties contain antimony. Decomposed by nitric acid, with separation of sulphur and arsenous oxide. Obs. — Occurs at Freiberg and elsewhere in Saxony ; at Joachimsthal ; Wolfach in Badeu ; Chalanches in Dauphine; Guadalcanal in Spain ; in Mexico: Peru ; Chili, at ChanarcOlo, in magnificent crystals. In Nevada, in the Daney mine, and in Comstock lode, but rare ; in veins about Austin, Lander Co. ; in microscopic crystals in Cabarrus Co., N. C, at the McMakin mine ; in Idaho, at the Poor Man lode. BOURNONITB. Radelerz, G'cr7ra.(="Wheel Ore). Orthorhombic. /A /= 93° 40', O N\-l = 136° 17' (Miller i ; t I \ a - 0-95G1S : 1-0GG2 : 1. O M-l = 133° 26', ^\ = 127° 20', 6 A 1-i = 138" 6'. Cleavage : i-l imperfect ; i-% and O less distinct. Twins : twinning, plane face 7/ ciystals often cruciform (f. 453), crossing at angles of 9S° 40' and '^'6° 20' ; hence, also, cog-wheel shaped. Also massive j granular, compact. 254 DESCRimVE MENEItALOOT. H.=2"5-3. G. = 5'7-5'9. Lustre metallic. Color and streak steel-gray, inclining to blackish lead-gray or iron-black. Opaque. Fractui'e con- choidal or uneven. Brittle. 452 458 Comp., Var — CuPbSbSs Ramm. (or SRS+SbjSa, with 3RS=2PbS+Cu2S)= Sulphur 19-6, antimony 25 0, lead 42-4, copper 13-0=100. Pyr., etc. — In the closed tube decrepitates, and gives a dark-red sublimate. In the open tube gives sulphurous oxide, and a white sublimate of antimonous oxide. B.B. on charcoal fuses easily, and at first coats the coal white, from antimonous oxide ; continued blowing gives a yellow coating of lead oxide; the residue, treated with soda in R.F. , gives a globule of copper. Decomposed by nitric acid, affording a blue solution, and leaving a residue of sulphur, and a white powder containing antim »ny and lead. Obs. — Occurs in the Harz ; at JCapnik in Transylvania; at Servoz in Piedmont; Brauns- dorf and Gersdorf in Saxony, Olsa in Corinthia, etc. ; in Cornwall ; in Mexico ; at Huasco- AJto in Chili ; at JVIachacamarca in Bolivia ; in Peru. Stylotypite. — An iron-silver-copper boumonite ; Copiapo, Chili. BOULANGERITE. In plumose masses, exhibiting in the fracture a crystalline structure , also granular and compact. H.=2-5-3. G.=5.75-6-0. Lustre metallic. Color bluish lead-gray; often covered with yellow spots from oxidation. Comp.— PbsSb^Se (or 3PbS+Sb2S3)=Sulphur 182, antimony 23-1, lead 58-7=100. Pyr. — Same as for zinkeuite. Obs. — Quite abundant at Molieres, department of Gard, in France ; also found at Nasaf jeld in Lapland ; at Nertschinsk : Ober-Lahr in Sayn-Altenkirchen ; Wolf sberg in the Harz ; near Bottino in Tuscany. Epiboulanqerite. — Probably a decomposition product of boulangerite (Websky) ; it con- tains more sulphur and less antimony. Altenberg, SUesia. WiTTiCHENiTE. — Composition CuaBiSs (or iiCu3S + Bi2S3)= Sulphur 19'4, bismuth 42.1, copper 38-5 = 100. Color steel-gray. Wittichen, Baden. KoBELLiTE. — PbsBiSbSo (or 3PbS-^-(Bi.Sb)2S3) Ramm. = Sulphur 16-8, antimony lO"?, bis- muth 18 2, lead 54-3 = 100. Color lead-gray to steel-gray. Hvena, Sweden. AtKiNiTE (NadUerz, Gm».).— CuPbBiSs (or Cu.>S+2PbS+BiiS3) = Sulphur 1G7, bismuth 30 -2, lead 36 0, copper 11-1 = 100. In acicular crystals, also massive. Color blackish lead gray. Beresof, Urals ; Gold Hill, North Carolina. BULPHAKSENITES, SULPHANTIMONITES, ETC. 255 {e) Gkoup TV. Formula K4(As,Sb,Bi)2S7=4:RS + (As,Sb, 61)283- TETRAHEDRITE.* Gray Copper Ore. Fahlerz; Antimon- and Quecksilberfablerz, Ccrw Isometric ; tetrahedral. Twins : twinniiig-plaiie octahedral, producing, when the composition is repeated, the form in f. 456. Also massive ; gran- ular, coarse, or fine ; compact or crypto-crystalline. 454 456 II.=3-4-5. G.=4-5-5-56. Lustre metallic. Color between light flint- gray and iron-black. Streak generally same as the color ; sometimes inclined to brown and chei-ry-red. Opaque ; sometimes subtranslucent in very thin splinters, transmitted color cherry-red. Fracture subconchoidal — uneven. Rather brittle. Oomp., Var.— CusSboS, (or 4Cu2S + Sb2S3), with part of the copper (Cuo) often replaced by iron (Fe). zinc (Zn), silver (Agra), or quicksilver (Hg), and rarely cobalt (Co), and part of the antimony by arsenic, and rarely bismuth. Ratio Aga + Cus : Zn+Fe generally =3 : 1. There are thus : A. An antimonial series; B. An arsenio-antimonial series; C. A bismuthic arsenio-anti- monial ; besides an arsenical, in which arsenic replaces all the antimony, and which is made into a distinct species named tetmatitite. Var. 1. Ordinary. Containing little or no sUver. Color steel-gray to dark-gray. 2. Argentiferous; Freibergite. Light steel-gray, sometimes iron-black. 3. Mercuriferous ; Schwatzite. Color gray to iron-black. The following analyses will serve as examples of these varieties : Ag 0-60 Ni Co 1 -64=98 59 Eammelsberg. 3:^9 10.48 Pb0-78=10000 " - Hg 17-27, Pb 0-21 Bi 81=100 V. Rath. Pyr.. eto. — Differ in the different varieties. In the closed tube all fuse and givo a dark- red sublimate of antimonous sulphide ; when containing mercury, a faint dark-gray sublimate appears at a low red heat ; and if much arsenic, a sublimate of arsenous sulphide first; forms. In the open tube fuses, gives sulphurous fumes and a white sublimate of antimony ; if arsenic is present a crystalline volatile sublimate condenses with the antimony ; if the ore contains mercury it condenses in the tube in minute metallic globules. B.B. on charcoal fuses, gives a coating of antimonous oxide and sometimes arsenous acid, zinc oxide, and lead oxide ; the arsenic may be detected by the odor when the coating is treated in R. F. ; the zinc oxide assumes a green color when heated with cobalt solution. The roasted mineral gives with the fluxes reactions for iron and copper ; with soda yields a globule of metallic copper. To determine the presence of a trace of arsenic by the odor, it is best to fuse the mineral on charcoal with soda. The preswice of mercury is best ascertained by fusing the S Sb As Cu Fe Zn ID Miisen 25 46 1915 4-93 39-88 3-43 3-50 (2) Meiseberg 24 80 25-56 30-47 3-52 3-:^9 (3) Kotterbach 22 58 19-34 2-94 35-34 0-87 0-69 256 DESCEIPnVE MINEEALOGT. pulverized ore in a closed tube with about three times its weight of dry soda, the metal subliming and condensing in minute globules. The silver is determined by cupellution. Decomposed by nitric acid, with separation of sulphur, and antimonous and arsenous oxides Obs. — The Cornish mines, near St. Aust. ; at Andreasberg and Clausthal in the Ilarz ; Kremuitz in Hungary ; Freiberg in Saxony ; Przibram in Bohemia ; Kahl in Spessart ; Kap- nik in Transylvania ; Dillenburg in Nassau ; and other localities. The ore containing mer- cury occurs in Schm Initz, Hungary ; at Schwatz in the Tyrol ; and in the valleys of Angina and Costollo in Tu.scany. Found in Mexico, at Durango, etc. ; at various mines in Chili ; in Bolivia ; at the Kellogg mines. Arkansas ; at Newburyport, Mass. In California in Mariposa Co. ; in Shasta Co. In Nevada, abundant at the Sheba and De Soto mines, Humboldt Co. ; near Austin in Landei Co. ; in Arizona at the Heintzelman mine, containing 1^ p. c. of silver ; at the Sana Rita mine. IIIOXITE {Drauns). — A bismuth tetrahedrite from Cremenz. Einfischthal, Switzerland. Malinowskite. — A tetrahedrite containing 9-13 p. c. lead, and 10-13 p. c. silver. District of Rocuay, Peru. (5th Append. Min. ChiU.) / TENNANTITE.* Graukupfererz, Germ. Isometric ; liolohedra], Phillips. Cleavage : dodecaliedral imperfect. Twins as in tetrahedrite. Massive forms unknown. IT. = 3-5-4. G.=4*37-4"53. Lustre metallic. Color blackish lead-gray to iron-black. Streak dark reddish-graj. Fracture uneven. Comp. — CUSAS2S7 (or 4CU2S-1-AS2S3), with Cuo replaced in part by Fe, Aga, etc., as in tetra- hedrite, with which it agrees in crystalline form. Pyr.— In the closed tube gives a sublimate of arsenous sulphide. In the open tube gives sulphurous fumes, and a sublimate of arsenous oxide. B.B. on charcoal fuses with intumes- cence and emission of arsenic and sulphur fumes to a dark-gray magnetic globule. The roasted mineral gives reactions for copper and iron with the fluxes; with soda on charcoal gives metallic copper with iron. Obs. — Found in the Cornish mines. Also at Skutterud in Norway, and in Algeria. JULIANITE (\Veb,sky) is near tennantite. G. =5-13. Rudelstadt, Silesia. Meneguinite has the composition Pb4Sb2S7(4PbS + Sb2S3) = Sulphur 173, antimony 16-8, lead 63 9=: 100. Resembles boulangerite. Bottino, Tuscany ; Schwarzenberg, Saxony. (/) Group V. Formula E5(As,Sb)2S8=5RS-f(A8,Sb)8S3. STEPHANTTE. Sprodglaserz, Germ. Orthorhombic. Ihl= 115° 39', OM-l= 132° 32^' ; c'.l:d = l-089'< : 1-5844 : 1. 6> A 1 = 127° 51', OM-l = 145° 34. Cleav- age : 2-1 and i-l imperfect. Twins : twinning-plane /y forms like those of aragonite frequent. Also massive, compact, and disseminated. II. = 2-2-5. G. = 6-269, Przibram. Lustre metallic. Color and streak iron-black. Fracture uneven. 457 Comp.— AgsSbSi (or 5Ag.,S-|-Sb2S,)=Su]phur 16-2, antimony 15-3, silver 68-5 = 100. Pyr. —In the closed tube decrepitates, fuses, and after long heating gives a faint sublimate of antimonous sulphide. In the open tube fuses, giving off antimonial fumes and sulphurous oxide. B.B. on charcoal fuses with projection of small particles, coats the coal with antimonoue oxide, which after long blowing is colored red from oxidized silver, and a globule of metallic silver is obtained. Soluble in dilute heated nitric acid, sulphur and oxide of antimony being deposited. BULPHAKSENITES, STTLPHANTTMONITES, ETC. 257 Oh a. — At Freiberg and elsewliere in Saxony ; at Przibram in Bohemia ; in Ilungary ; at Andreasberg ; at Zacatecas in Mexico ; and in Peru. In Nevada, an abxindant silver ore in the Corastock lode ; at Ophir and Mexican mines in fine crystals ; in the Reese river and Humboldt and other regions. In Idaho, at the silver mines. Geocronite. — Composition PbsSbjSe (or 5PbS + SboS3) = Sulphur 16'7, antimony 15-9, lead 674=100 (also contains a little arsenic). Color light lead-gray. Sala, Sweden; Merido, Suaiii ; Val di Castello, Tuscany. POLYBASITB. Oi-thoihorabic, De ^1. /A / nearly 120°, 6> A 1 = 121° 30'. Crystals usiially short tabular prisms, with the bases triangularly striated parallel to alternate edges. Cleavage : basal imperfect. Also massive and dis- seminated. H.=2-3. G. = 6*214. Lustre metallic. Color iron-black ; in thin crys- tals cherry-red by transmitted light. Streak iron-black. Opaque except when quite thin. Fracture uneven. Comp. — Ag.jSbSe (or OAgjS+SbaSj), if containing silver without copper or arsenic, Sulphur 14"8, antimony 9*7, sUver 95 5=100. But with Agj replaced in part by Cua (ratio Ag : Cu= 1 : 4 to 1 : 11), and Sb replaced by As (ratio 1 : 1, etc.). Pyr., etc. — In the open tube fuses, gives sulphurous and antimonial fumes, the latter fonning a white sublimate, sometimes mixed with crystalline arsenous oxide. B.B. fuses with spirting to a globule, gives off sulphur (sometimes arsenic), and coats the coal with anti- monous oxide ; with long-continued blowing some varieties give a faint yellowish- white coat- ing of zinc oxide, and a metallic globule, which with salt of phosphorus reacts for copper, and cupelled with lead gives pure silver. Decomposed by nitric acid. Obs. — Occurs in Mexico ; at Tres Puutos, ChiU ; at Freiberg and Przibram. In Nevada, at the Reese mines ; in Idaho, at the silver mines of the Owhyhee district. PoLYARGYRiTE. — Isometric. Cleavage cubic. Malleable. Comp. ISAgaS+SbaSj. Wol- fach, Baden. ENARGITE. Orthorhombic. IaI= 97° 53', Oa1-1 = 136° 37' (Dauber) ; c : ^ : a — 0-94510 : 1-1480 : 1. O M-i = 140° 20', 0M = 128° 35'. Cleavage : / perfect ; i-l, i-i distinct ; indistinct. Also massive, granular or columnar. H.=3. G.=4-43-4-45 ; 4-362, Kenngott. Lustre metallic. Color gray- ish to iron-black ; streak grayish-black, powder having a metallic lustre. Brittle. Fractui-e uneven. Comp. — Cu 3 Asa 4 = Sulphur 'S2 5, arsenic 19 1, copper 48*4=100, usually containing also a little antimony, and zinc, and sometimes silver. i.-'yr. — In the close'i tube decrepitates, and gives a sublimate of sulphur ; at a higher tem- perature fuses, and gives a sublimate of arsenous sulphide. In the open tube, heated gently, the powdered mineral gives off sulphurous and arsenous oxides, the latter condensing to a sublimate containing some antimonous oxide. B. B. on charcoal fuses, and gives a faint coat- ing of arsenous oxide, antimonous oxide, and zinc oxide ; the roasted mineral with the fluxea gives a s'lobule of metallic copper. Soluble in nitro-hydrochloric acid. 17 258 DESCKEPnVE MINEKALOGY. Obs — From Morococha, Cordilleras of Peru; Famatina Mta., Argentine Republic; from Chih ; mines of Santa Anna, N. Granada ; at Cosihuirachi in Mexico ; Brewster's gold mine Chesterfield district, S. Carolina ; in Colorado ; at WilliB's Gulch, near Black Hawk ; southern Utah ; Morning Star mine, Cal. Famatinite {!Ste'.zner).—kn. antimonial enargite. Massive. Color reddish gray Fama- tina Mts., Argentine Republic ; Cerro de Pasca, Peru. LuzoNiTE.— Similar to enargite in composition, but unlike in form, according to Weisbach Mancayan Island, Luzon. Claiute (Sandberger) — Also similar to enargite in composition, but in form monoclinic and having a perfect cleavage parallel to the clinopinacoid. Schapbach, Black Forest ' EriGENiTE.— Composition S 32-24, As 12-78, Cu 40 68, Fe 14-20=100. Orthorhombia Color Bteel-gray. Neugliick mine, Wittichen. OOMPOIINDS OF CHLORINE, BKOMINE, lODINB. 259 lU. COMPOUNDS OF CHLORINE, BROMINE, IODINE 1. ANHYDROUS CHLORIDES, ETC. HALITE. COMMON SALT. Kochsalz, Steinsalz, Oerm. Isometric. Usually in cubes ; rarely in octahedrons ; faces of crystala sometimes cavernous, as in f. 458. Cleavage: cubic, perfect. Massive and granular, rarely columnar. H.=:2-5. G.=2-l-2-257. Lustre vitreous. Streak white. Color white, also sometimes yellowish, red- dish, bluish, purplish; often colorless. Transparent — translucent. Fracture conchoidal. Rather brittle. Soluble ; taste purely saline. Oomp.—NaCl= Chlorine 60 7, sodium 39-3=100. Commonly mixed with some calcium sulphate, calcium chloride, and magne- sium chloride, and sometimes magnesium sulphate, which render it liable to deliquesce. Pyr. etc. — In the closed tube fuses, often with decrepitation ; when fused on the platinum loop colors the flame deep yellow. Diflf. — Distinguished by its taste, solubility, and perfect cubic cleavage. Obs. — Common salt occurs in extensive but irregular beds in rocks of various ages, associ- ated with gypsum, polyhaUte, calcite, clay, and sandstone ; also in solution, and forming salt springs. The principal mines of Europe are at Wieliczka, in Poland ; at Hall, in the Tyrol • Stass- furt, in Prussian Saxony ; and along the range through Reichenthal in Bavaria, Hallein in Salzburg, Hallstadt, Ischl, and Ebensee, in upper Austria, and Aussee in Styria ; in Transyl- vania ; Wallachia, Galicia, and upper Silesia ; Vic and Dieuze in Prance ; Valley of Cardona and elsewhere in Spain, forming hills 300 to 400 feet high ; Bex in Switzerland ; and North- wich in Cheshire, England. It also occurs near Lake Oroomiah, the Caspian Lake., etc. In Vlgeria ; in Abyssinia ; in India in the province of Lahore, and in the valley of Cashmere • in China and Asiatic Russia ; in South America, in Peru, and at Zipaquera and Nemocon. In the United States, salt has been found forming beds with gypsum, in Virginia, Wash- ington Co. ; in the Salmon River Mts. of Oregon ; in Louisiana. Brine springs are very numerous in the Middle and Western States. These springs are worked at Salina and Syra- cuse, N. Y. ; in the Kanawha Valley, Va. ; Muskingum, Ohio ; Michigan, at Saginaw and elsewhere ; and in Kentucky. Vast lakes of salt water exist in many parts of the world. Lake Timpanogos in the Rocky Mountains, 4,200 feet above the level of the sea, now called the Great Salt Lake, is 2,000 square miles in area. L. Gale found in this water 20*196 per cent, of sodium chloride in 1852 ; but the greater rainfall of the last few years has dimin- ished the proportion of saline matter. The Dead and Caspian Seas are salt, and the waters of the former contain 20 to 26 parts of solid matter in 100 parts. HuANT.\J.VYiTE. — Composition 20NaCl + AgCl. Occurs in white cubes in the mine of San Simon, Cerro de Huantajaya, Peru. 260 DESOEIPTTVE MrNERALOGT. SYLVITE. Isometric. Cleavage cubic. Also compact. H. = 2. G.=l-9-2. White or colorless. Vitieous. Soluble; tasle like that of common salt. Comp. — KC1 = Chlorine 47 Go, potassium 52-35 = 100. But often containing impurities. Pyr., etc. — B. B. in the platinum loop fuses, and gives a violet color to the outer flame. Added to a salt of phosphorus bead, which has been previously saturated with copper oxide, colors the O.F. deep azure-blue. Water completely dissolves it. Obs. — Occurs at Vesuvius, about the fumaroles of the volcano. Also at Stassfurt ; at Leo- poldshall {leopoklite) ; at Kalusz, Galicia. OERARGYRITE. Kerargyrite. Horn Silver. Silberhomerz, Germ. Isometric. Cleavage none. Twins: twinning-plane octahedral. Usually massive and looking like wax ; sometimes columnar, or bent columnar ; often in crusts. H. = l-l-5. G. = 5'552. Lustre resinous, passing into adamantine. Color pearl-gi-ay, grayish-green, whitish, rarely violet-blue, colorless sometimes when perfectly pure ; brown or violet-brown on exposure. Streak shin- ing. Transparent — feebly subtranslucent. Fracture somewhat conchoidal. Sectile. Comp AgCl=Chlorine 247, silver 75-3=100. Pyr., etc. — In the closed tube fuses without decomposition. B.B. on charcoal gives a globule of metallic silver. Added to a bead of salt of phosphorus, previously saturated with copper oxide, and heated in O.F., imparts an intense azure-blue to the flame. A fragment placed on a strip of zinc, and moistened with a drop of water, swells up, turns black, and finally is entirely reduced to metallic silver, which shows the metallic lustre on being pressed with the point of a knife. Insoluble in nitric acid, but soluble in ammonia. Obs. — Occurs in veins of clay slate, accompanying other ores of silver, and usually only in the higher parts of these veins. It has also been observed with ochreous varieties of brown iron ore ; also with several copper ores, with calcite, barite, etc. The largest masses are brought from Peru, Chili, and Mexico. Also occurs in Nicaragua near Ocotal ; in Honduras. It was formerly obtained in the Saxon mining districts of Johanngeorgenstadt and Freiberg, but is now rare. Found in the Altai; at Kongsberg in Norway ; in Alsace ; rarely in Cornwall, and at Huelgoet in Brittany. In Nevada, about Austin, Lander Co., abundant ; at mines of Comstock lode. In Arizona, in the Willow Springs dist. , veins of El Dorado cafion, and San Francisco dist. In Idaho, at the Poor Man lode. Named from icipar, horn, and «?> fp^f, silver. Calomel (Quecksilberhomerz, (?e;-m.).— Composition HgCl=Chlorine 15-1, mercury 84-9 -=100. Color white, grayish, brown. Spain. SAii Ammoniac (Salmiak, Oerm.). — Ammonium chloride, NH4C1= Ammonium 33-7, chlo- rine 66-3=100. Vesuvius, Etna, and many volcanoes. Nantokite (Breithaupt).— Composition CuCl=Chlorine 359, copper 64 1=100. Cleavage cubic. Color white. Nantoko, Chili. Embolite.— Ag(Cl,Br) ; the ratio of CI : Br varying from 3 : 1 to 1 : 3. Color grayish- green. At various mines in Chili ; also Mexico ; Honduras. BuoMYKiTE, Bromargyrite (Bromsilber, 6'«?-m.). — Silver bromide. AgBr=Bromine 426, Bilver 57-4 = 100. Color when pure bright yellow, slightly greenish. Chili ; Mexico. loDVRiTE, lodargyrite (lodsilber, Germ.). — Silver iodide, Agl = Iodine 540, silver 46-0— 100. Color yellow. Mexico ; Chili ; Spain ; Cerro Colorado mine in Arizona. TocoRNALiTE (Domeyko). — Composition Agl+Hgl. Amorphous. Color pale yellow. Chanarcillo, ChilL CnLOROCALCiTE (Scacchi). — From Vesuvius, contained 5876 p. c. CaCl.^ ; with also KGl, NnCl.MgCla. Chlorallumlnite, CnLOBMAdNESiTE, and Chlokothionite are also frcm Vesuvius. COMPOUNDS OF CHLORINE, BROMINE, IODINE. 261 sf COTUNNITE.— Lead chloride, PbCl2=Clilorme 25-5, lead 74-5=100. Soft. White. Vegu •nns. PsEUDOCOTUNNiTE (^Scacchi), Vesuvius. MOLYSITE. — Composition FeCl«= Chlorine 65*5, iron 34-5=100. Vesuvin*. 2. HYDROUS CHLORIDES. CARNALLITE. Massive, granular ; flat planes developed by action of water, but no dis- tinct traces of cleavage ; lines of striae sometimes distinguished, which indicate twin- composition. Lustre shining, greasy. Color milk-white, but often reddish from mix- ture of oxide of iron. Fracture conchoidal. Soluble. Strongly pho.sphor escent. Comp. — KMgCl3.6aq=KCl+MgCla + 6aq=Magnesium chloride 34 '2, potassium chloride 2G-0, water 38 -y- 100. The browTi and red color of the mineral is due partly to iron sesquioxide, which is in hex- agonal tables, and partly to organic matters (water-plants, infusoria, sponges, etc.). Pyr., etc. — B.B. fuses easily. Soluble in water, 100 parts of water at 18'75° C. taking up 6 15 parts. Obs. — Occurs at Stassfurt, where it forms beds in the upper part of the salt formation, alternating with thiuner beds of common salt and kieserite, and also mixed with the common salt. Its beds consist of subordinate beds of different colors, reddish, bluish, brown, deep red, Bometimea colorless. Sylvite occurs in the camallite. Also found at We.steregeln ; with salt at Maiiian in Persia. Its richness in potassium makes it valuable for exploration. Taciiiivdkitk.— Composition CaMggClB + 12aq=CaClo + 2MgC1.2 + 12aq (Ramm.) = Chloiine 40 '3, magnesium 9 '5, calcium 7 5, water 427=100. Color yellowish. Deliquescent. Stass- furt. Kkemersite. — Probably 2NH4Cl-|-2KCl-|-FeCle+3aq. Vesuvius. Erythkosidkrite, also from Vesuvius, is 2KCl+FeCl8+2aq. 3. OXYCHLORIDES. ATACAMITE. Orthorhombic. 7 A / = 112° 20', O M-% - 131° 29' ; c\l\a^ I'lSi : 1*492 : 1. Usually in modified rectangular prisms, vertically striated ; also in rectangular octahedrons. Twins: twinuing-plane /; coiiaiating of three individuals. Cleavage: i-l perfect, 1-i imperfect. Occurs also mas- aive lamellar. H.= 3-3-5. G.=3'761 (Klein), 3-898 (Zepharovich). Lustre adamantine- vitreous. Color various shades of bright green, rather darker than emerald, sometimes blackish-green. Streak apple-gi-een. Translucent — subti-an* lucent. 262 DESCRIPTIVE MINEEALOGT. Comp.—CuCl3+3HjOaOj= Chlorine 16-64, copper 5945, oxygen 11-25, water 12-66=100. Also other compounds with more water (18 and 22^ p. c). Pyr., etc. — In the closed tube gives off much water, and forms a gray sublimate. B.B. on '-•haircoal fuses, coloring the O.F. azure-Dlue, with a green edge, and giving two coatings, one brownish and the other grayish-white ; continued blowing yields a globule of metallic copper ; the coatings touched with the R.F. volatilize, coloring the flame azure-hluo. In acida easily soluble. Obs. — Occurs in different parts of Chili ; in the district of Tarapaca. Bolivia ; at Tocopilla in Bolivia ; with malachite in South Australia ; Serro do Bembe, near Ambriz, on the west coast of Africa ; at the Estrella mine in southern Spain ; at St. Just in Cornwall. Tai-lingite. — Composition CuCla+4H3CuOa+4aq. In thin crusts. Color blue, Botal* lack mine, Cornwall. Atelite. — Composition CuCli-f 2H2Cu03 + aq. Formed from tenorite. Vesuvius. Percylite. — An oxychloride of lead and copper. Occurs in minute sky-blue cubes. Sonora, Mexico ; So. Africa, Matlockite. — Composition EbCla+PbO=Leadchloride55'5, lead oxide 44-5 = 100. Crom- ford, near Matlock, Derbyshire. Mendipite. — Composition PlCU-f 2PbO=Lead chloride 384, lead oxide 61 6=100. In columnar masses, often radiat(d. Color white. Mendip Hills, Somersetshire; Brillon, Westphalia. ScHTVAUTZEMBERQiTE. — Composition Pb{I,Cl)2+2PbO. Color yellow. Desert of Ata- cama, Daubreite.— Composition (Bij03)4BiCla=Bia03 76-16, BiCla 28-84=100. Amorphous, Structure earthy, sometimes fibrous. Color yellowish-gray. H.=2-5. G. =6-4-6 5. From the mine Constancia, Cerro de Tanza, Bolivia (Domeyko). irLUOBINE COMPOUNDS. 263 IV. FLUORINE COMPOUNDS. 1. ANHYDROUS FLUORIDES. FLUORITE or FLUOR SPAR* Flusapath, Germ. Isometric; forms usually cubic (see f. 39, 40, to 19). Cleavage : octahedral, perfect. Twins : twiuning-plane, 1, f. 266, p. 91. Massive. Rarely Columnar ; usually granular, coarse or fine. ^ Crystals often having the surfaces made up of small cubes, or cavernous with rectangular covities. il.=4. G.=3-01-3-25, Lustre vitreous ; bometimes splendent ; usually glimmering in the massive varieties. Color white, yellow, green, rose, and crimson-red, violet-blue, sky-blue, and brown : wine-yellow, greenish and violet-blue, most common ; red, rare. Streak white. Trans- parent — subtranslucent. Brittle. Fracture of fine conchoidal and splintery. Sometimes presenting Phosphoresces when heated. 41, 52, 55, etc., pp. 10 459 massive varieties flat* a bluish fluorescence. Comp., Var Calcium fluoride, CaFa=Fluorine 48*7, calcium 51 -3=100. Berzelius found -5 of calcium phosphate in the fluorite of Derbyshire. The presence of chlorine was detected early by Scheele. Kersten found it in fluor from Marienberg and Freiberg. The bright colors, as shown by Kenngott, are lost on heating the mineral ; they are attributed mainly to different hydrocarbon compounds by Wyrouboff, the crystallization having taken place from aqueous solution. Var. Ordinary ; (ff) cleavable or crystallized, very various in colors ; (J) coarse to fine granular ; (c) earthy, dull, and sometimes very soft. A soft earthy variety from Ratofka, Russia, of a lavender-blue color, is the ratofkite. The finely-colored fluorites have been called, according to their colors, false ruby, topaz, emerald, amethyst, etc. The colors of the phosphorescent light are various, and are independent of the actual color ; and the kind affording a green color is id) the clihrophane. Pyr., etc. — In the closed tube decrepitates and phosphoresces. B.B. in the forceps and on charcoal fuses, coloring the flame red, to an enamel which reacts alkaline to test paper. With soda on platinum foil or charcoal fuses to a clear bead, becoming opaque on cooling ; with an excess of soda on charcoal yields a residue of a difficultly fusible enamel, while most of the soda sinks into the coal ; with gypsum fuses to a transparent bead, becoming opaque on cooling. Fused in an open tube with fused salt of phosphorus gives the reaction for fluor* ine. Treated with sulphuric acid gives fumes of hydrofluoric acid which etch glass. PhoS' 264 DESCRIPTIVE anNERALOOY. phorescence is obtained from the coarsely powdered spar below a red heat. At a high tem- perature it ceases, but is partially restored by an electric discharge. Difif. — Recognized by its octahedral cleavage, its etching power when heated in the glass tube, etc Obs. — Sometimes in beds, but generally in veins, in gneiss, mica slate, clay slate, and also in limestones, both crystalline and nncrystalline, and sandstones. Often occurs as the ganguc tJf metallic ores. In the North of England, it is the gangue of the lead veins. In Derby- shire it is abundant, and also in Cornwall. Common in the mining district of Saxony ; fine near Kongsberg in Norway. In the dolomites of St. Gothard it occurs in pink octahedrons Some American localities are : Trumbull and Plymouth, Conn. ; Muscolonge Lake, Jeffer- son Co., N. Y., in gigantic cubes ; Rossie, St. Lawrence Co. ; near the Franklin furnace, N. J. ; Gallatin Co., 111. ; Thunder Bay, Lake Superior; Missouri. Sellaite (Striiver).— Magnesium fluoride, MgFa. Tetragonal. Colorless. Occurs with anhydrite at Gerbulaz in Savoy. Yttroceiute.— Composition 2(9CaF2+2YF2 + CeFo)-)-.8aq (Ramm.). Color violet-blue, white. Near Fahlun, Sweden ; Amity, N. Y. ; Paris, Me. ; etc. Fluocerite.— Contains (Berzelius) ^eOa 82-64, YO 1-12. Sweden. Fluellite. — Contains (Wollaston) fluorine and aluminum. Cornwall. Cryptohalite. — FluosOicate of ammonium. Vesuvius. Also observed at Vesuvius, hydrojluorite, HF, and proidonite, SiFi (Scacchi). CRYOLITE.* 460 Triclinic (DesCloizeaiix and Webskj). Form approaching very closely in appearance and angles to the cube and cubo- ■ octahedron of the isometric system. General liabit as in f. 460 ; F{0) A T{I) = 90=^ 2', F{0) A J/(7') = 90° 24', J/A T(lA 1') = 91° 57' ; also I {l-V) A M {/') = 124° 30', I {1-i') A T(I) = 124° 14' (angles by ^yebskJ). Twins common. Cleavage parallel to the three planes P, 31, T ; in crystals most com- plete parallel to T, in masses parallel to P. Com- monly massive, cleavable. II.=2-5. G. = 2-9-3'077. Lustre vitreous; slightly pearly on O. Color snow-white ; sometimes reddish or brownish to brick-red and even black. Sub- transparent — translucent. Immersion in \vater creases the transparency. Brittle. m- Comp.— NaeAlFio (or 6NaF+AlF6)= Aluminum 13-0, sodium 32-8, fluorine 54-2=100. Pyr., etc. — Fusible in the flame of a candle. B.B. in tbe open tube heated so that tho flarne enters the tube, gives off hydrofluoric acid, etching the glass ; the water which con- denses at the upper end of the tube reacts for fluorine with Brazil-wood paper. In the for- ceps fuses very easily, coloring the flame yellow. On the charcoal fuses easily to a clear bead, which on cooling becomes opaque ; after long blowing, the assay spreads out, the sodium fluoride is absorbed by the coal, a suffocating odor of fluorine is given off, and a crust of alumina remains, which, when heated with cobalt solution in 0. F. , gives a blue color. Soluble in sulphuric acid, with evolution of hydrofluoric acid. Diff. — Distinguished by its extreme fusibility, and its yielding hydrofluoric acid in the open tube. Obs.— Occurs in a bay in Arksut-fiord, in West Greenland, at Evigtok, where it constitutes A large bed or vein in gneiss. It is used for making soda, and soda and alumina salts ; also in Pennsylvania, for the manufacture of a white glass which is a very good imitation of porcelain. CmoLiTE.—G. =2-84-2 -90. NasAlFs (or SNaF+AlFg). Cuodneffite.— G.=3-01. Naj^ Pio (or4NaF-f AlFo) Ramm. The two minerals are alike in physical characters, occurring in minute tetragonal pyramids ; both from Miask. FLUORINE COMPOUNDS. 265 2. HYDROUS FLUORIDES. PAOHNOLITE. ThomsenoUfce.* V ^ Monoclinic, with the lateral axes equal (" clino-quadratic " Nordeim kiold). c\h:d = 1-044 : 1 : 1 ; ^ =r 92° 30'. Prisms slender, a little tapering ; I horizontally striated. Cleavage : basal 460a very perfect. Also massive, opal or chalcedony-like. II.=:2-5-4. G. = 2-929-3-008, of crystals. Lustre vitreous, of a cleavage-face a little pearly, of massive waxy. Color white, or with a reddish tinge. Transparent to translucent. Comp Na^CaiAlFia -t- 2aq, or 2NaF -f- 2CaFo + AIFe -t- 2aq = Fluorine 51.28, aluminum 12-28, calcium 17-99, sodium 10-35. water 810 — 100. Pyr., etc. — Fuses more easily than cryolite to a clear glass. The massive decrepitates remarkably in the flame of a candle. In powder easily decom- posed by sulphuric acid. Obs. — Found incrusting the cryolite of Greenland, and a result of its alteration. The crystals often have an ochre-colored coating, especially the terminal portion; they are sometimes quite large, and have much the appearance of cryolite The mineral was first described by Knop, and though his descripticn of the crystals does not agree with that givea above, there seems to be no doiibt that the material was the same, which has since been investigati d by Hageraann {dimetric pachnoUte —thomnenolite), Wohler (pyroconite) and Kcenig, as urgfd by the latter. Knop originally described two varieties of the mineral, to which he gave the name pachno- lite. The variety. A, appeared in large, cuboidal crystals, with cleavage planes parallel to the faces, intersecting at angles of approximately 90^. These cleavage planes seemed to be con- tinued on into the mass of the cryolite on which the crystals were implanted. The second variety, B, was in small brilliant crystals, of prismatic form, grouped together often in par- allel position upon the cryolite (hence the name, from wdxi'v, frost). The identity of the two varieties chemically was shown by the analyses of Knop and Wohler. The crystals of variety B, according to Knop, had 7a /= 81° 24', etc. Knop has recently (Jahrb. Min., 1876, 849) suggested the possibility that the crystals of " cryolite," upon which Websky obtaicied the angles quoted on the preceding page, were really identical with variety A of pachnoUte. The crystallographic relation of the two species is not yet clearly made out. Akksutite, Hagemannite, Gearksutite, all from Greenland ; and Prosopite, from Altenberg. — Fluorine minerals, related to those which precede, but whose exact nature ia not yet known. Ralstonite {Brush). — An hydrous aluminum fluoride, containing also a little magnesium and sodium. Occurs in minute regular octahedrons on the cryolite from Greenle nd. 266 DESCKIPnVE MINEEALOGT. V. OXYGEN COMPOUNDS. 1. OXIDES OF Metals of the Gold, Iron, or Tin Groups. 461 A. ANHYDROUS OXIDES, (a) Protoxides, RO(or 11,0). CUPRITE. Red Copper Ore. Rothkupfererz, Germ. Isometric (see figures on p. 17). Cleavage: octahedral. Sometiinea cubes leugtlieued into capillary forms. Also massive, granular; sometimes earthy. H.=3-5-4. G.=5-S5-6'15. Lustre ada- mantine or submetallic to earthy. Color red, of various shades, particularly cochineal-red ; occasionally ciirason-red by transmitted light Streak several shades of l3rownish-red, shin ing. Subtransparent — subtranslucent. Frao ture conchoidal, uneven. Brittle. Comp., Var — Cu20=0xygen 11-2, copper 88-8=100 Sometimes aflfords traces of selenium. ChnlcotncJdti is a variety which occurs in capillary or acicular crys- tallizations, which are cubes elongated in the direction of the octahedral axis. It also occurs earthy ; Tilt Ore (Ziegelerz Germ.). Brick-red or reddish-brown and earthy, often mixed with red oxide of iron ; some- times nearly black. Pyr., etc. — TJnaltered in the closed tube. B.B. in the forceps fuses and colors the flame emerald-green; if previously moistened with hydrochloric acid, the color imparted to the flame is momentarily azure-blue from copper chloride. On charcoal first blackens, then fuses, and is reduced to metallic copper. With the fluxes gives reactions for copper oxide. Soluble in concentrated hydrochloric acid. Obs. — Occurs in Thuringia ; on Elba, in cubes ; in Cornwall ; in Devonshire ; in isolated crystals, in lithomarge, at Chessy, near Lyons, which are generally coated with malachite, etc. At the Somerville, and Flemington copper mines, N. J. ; at Cornwall, Lebanon Co., Pa. ; in the Lake Superior region. Htdrocuprite {Oenth). — A hydrous cuprite. Occurs in orange-yellow coatings on rTi-gnetite. Cornwall, Lebanon Co., Pa, ZINCITE. Red Zinc Ore. Rothzinkerz, Germ. Hexagonal. O M = 118° 7' ; c = 1-6208. In quartzoids with truncated summits, and prismatic faces /. Cleavage : basal, eminent ; prismatic, sometimes distinct. Usual in foliated grains or coai-se particles and masses; also granular. II.=4-4-5. G.=5'43-5-7. Lustre subadamantine. Streak orange-yel- low. Color deep red, also orange-yellow. Translucent — subtranslucent. Fracture subconchoidal. Brittle. Comp. — ZnO= Oxygen 19 "74, zinc 80'2G=100; containing manganese as an unessential ingredient. The red color is due probably to the presence of manganese sesquioxide, cer- tainly not to scales of hematite. OXYGEN COMPOUNDS — Alf HYDROUS OXIDES. 267 Pyr., etc. —Heated in the closed tube blackens, but on cooling resumes the original color. B.B. infusib.e ; with the fluxes, on the platinum wire, gives reactions for manganese, and on charcoal in R. F. gives a coating of zinc oxide, yellow while hot, and white on cooling. The coating, moistened with cobalt solution and treated in R.F., assumes a green color. Soluble in acids %vithout efifervescence. Obs. — Occurs with franklinite and also with c^lcite at Stirling Hill and Mine Hill, Sussex Co., N.J. — Calcozincite. — Impure zincite (mixed with CaCOs, etc.). Stirling Hill, N. J. TENORITE.* Melaconite. Schwarzkupfererz (Kupferschwarze), Germ. Orthorbombic (tenorite), crystals from Yesuvins. Eartbv ; massive; pulverulent (melaconite) ; also in shining flexible scales ; also rarely in cubes with truncated angles (psendomorphous ?). H.=3^ G.=6*25, massive (Whitney). Lnstre metallic, and color steel or iron-gray when in thin scales ; dirll and earthy, with a black or grayish- black color, and ordinarily soiling the fingers when massive or pulverulent. Oomp — CuO=Oxygen 2015, copper 79 •85=100 Pyr., etc. — B.B. in O.F. infusible; other reactions as for cuprite (p. 244). Soluble in hydrochloric and nitric acids. Obs. — Found on lava at Vesuvius in minute scales ; and also pulverulent (Scacchi, who uses the name melaconise for the mineral). Common in the earthy form [melaconite) about copper mines, as a result of the decomposition of chalcopyrite and other copper ores. Duck- town mines in Tennessee, and Keweenaw Point, L. Superior. Periclasite. — Essentially magnesium oxide, MgO, or more exactly (Mg,Fe)0, where Mg : Fe=20 : 1, or 30 : 1. Mt. Somma. BUNSENITE. — NiO. Found at Johanngeorgenstadt. The compound MnO has been found recently in Wermland, in masses of a green color, and with cubic cleavage. See mangano- site, p. 431. Massicot (Bleiglatte). — PbO, but generally impure. Badenweiler, Baden. Mexico. Austin's mines, Va. Hydrargyrite. — HgO; with Bordosite, AgCl + HgCl, at Los Bordos, Chili. (J) Sesquioxides. General Formula ftOj, CORUNDUM.* Khombohedral. .^ A ^ = 86° 4', 6^ A \{R) = 122° 26' ; (122° 25', Kok- scharof) ; c = 1-363. Cleavage : basal, some- 462 463 times perfect, but interrupted, commonly im- perfect in the blue variety; rhombohedral, often perfect. Large crystals usually rough. Twins : composition-face H, Also massive granular or impalpable ; often in layers from composition parallel to /i. II.=9. G. = 3-909-4:-16. Lustre vitreous ; sometimes pearly on the basal planes, and occa- sionally exhibiting a bright opalescent star of six rays in the direction of the axis. Color h\x\e, red, yellow, brown, gray, and nearly wl ite ; streak uncolored. Transparent — translucent. Fracture conchoidal — uneven. Exceedingly tough when c(^mpact. Comp., Var. — Pure alumina A103=0xygen 46'8, aluminum 53"2=100. There are three 268 DESCRITTIYE MINERALOGY. Bubdivisions of the species prominently recognized in the arts, and until eaily in this century regarded as distinct species ; but which actually differ only in purity and state of crystalliza- tion or stru ture. Var. 1. Sapphire — Includes the purer kinds of fine colors, transparent to translucent, useful as gems. Stones are named according to their colors ; true Ruby^ or Oriental Ruby, red ; Topas, yellow ; 0. Emerald, green ; 0. Amrtlii/st, purple. 2. Corundum. — Includes the kinds of dark or dull colors and not transparent, colors light blue to gray, brown, and black. The original adamantine spar from India has a dark gray- ish smoky-brown tint, but greenish or bluish by transmitted light, when translucent, and either in distinct crystals often large, or cleavable-massive. It is ground and used as a polish- ing material, and being purer, is superior in this re.'spect to emery. It was thus employed in ancient times, both in India and Europe. 3. Emejby, Schmirgel, Germ. — Includes granular corundum, of black or grayish-black color, and contains magnetite or hematite intimately mixed. Feels and looks much like a black fine-grained iron ore. which it was long considered to be. There are gradations from the evenly fine-grained emery to kinds in which the corundum is in distinct crystals. This last is the case with part of that at Chester, Massachusetts. Pyr., etc. — B.B. unaltered ; slowly dissolved in borax and salt of phosphorus to a clear glass, which is colorless when free from iron ; not acted upon by soda. The finely pulverized mineral, after heating with cobalt solution, gives a beautiful blue color. Not acted upon by acids, but converted into a soluble compound by fusion with potassium bisulphate or soda. Friction excites electricity, and in polished specimens the electrical attraction con- tinues for a considerable length of time. Diff. — Distinguished by its hardness, scratching quartz and tp^az ; its infusibUity and its high specific gravity. ~Obs.— This species is associated with crystalline rocks, as granular limestone or dolomite, gneiss, granite, mica slate, chlorite slate. The fine sapphires are usually obtaii^ed from the beds of rivers, either in modified hexagonal prisms or in rolled masses, accompanied by grains of magnetic iron ore, and several species of gems. The emeiy of Asia Minor, according to Dr. Smith, occurs in granular limestone. Sapphires occur in Ceylon ; the East Indies ; China Corundum, at St. Gothard ; in Pied- mont ; Urals ; Bohemia. Emery is found in large boulders on some of the Grecian islands ; also in Asia Minor, near Ephesus, etc. In N. America, in Mnssacfni setts, at Chester, corun- dum and emery in a large vein ; also in "Westchester Co. , N. Y. In New York, at Warwick and Amity. In Pennsylvania, in Delaware Co., and Chester Co. In western iV. Carolina, at many localities in large quantities, and sometimes in crystals of immense size. In Oeorgia, in Cherokee Co. In California, in Los Angeles Co. ; in the gravel on the Upper Missouri Iliver in Montana. HEMATITE. Specular Iron. Eisenglanz, Rotheisenerz, Germ. Rhorabohedral. ^ A i? = 86° 10', OnE = 122° 30' ; c = 1 -3591. (^ A f 2 = 118° 53', 6> A 1^ = 103° 32, i? A f 2 = 154° 2'. Cleavage : par- allel to R and O ^ often indistinct. Twins: twinning-plane R ', also 465 466 Vesuvius. Elba. Elba. (f. 267, p. 91). Also columnar — granular, botryoidal, and stalactitic sha])efc , also lamellar, laminae joined parallel to O^ and variously bent, tliick xw thin ; also granular, friable or compact. OXYGEN COMPOUNDS — ANHTDEOUS OXIDES. 269 H.=:5'5-6-5. G.=4-5-5*3; of some compact varieties, as low as 4-2 Lustre inetallic and occasionally splendent ; sometimes earthy. Color dark steel-graj-^oT- iron-black ; in vei-y thin particles blood-i-ed by transmitted light; when earthy, red. Streak cherry-red or reddish-brown. Opaqne, except when in veryUiin laminae, which are faintly translucent and blood- red. Fracture subconchoidal, uneven. Sometimes attractable by the magnet, and occasionally even magnetipolar. Comp., Var. — Iron sesquioxide, FeOa^Oxygen 30, iron 70=100. Sometimes contaiojnf titanium and magnesium. The varieties depend on texture or state of aggregation, and in some cases the presence v impurities. Var. 1. Specul/ir. Lustre metallic, and crystals often splendent, whence the name «pec«?ar iron, (b) When the structure is foliated or micaceous, the ore is called micaceous hematito (Eisenglimmer). 2. Compact columnar ; or fibrous. The masses of ten long radiating ; lustre sabmetallic to metallic ; color brownish-red to iron-black. Sometimes called rid het7iatite, the name hematite among the older mineralogists including the fibrous, stalactitic, and other solid massive varieties of this species, limonite, and turgite. 3. Bed Ochreoiis. Red and earthy. Often specimen.s of the preceding are red ochreous on some parts. Reddle and red c•/<^/^^• are red ochre, mixed with more or less clay. 4. Clay Iron-slone ; Argillaceous hematite. Hard, brownish-black to reddish-brown, heavy stone ; often in part deep-red ; of submetallic to unmetallic lustre ; and affording, like all the preceding, a red streak. It consists of iron sesquioxide with clay or sand, and sometimes other impurities. Pyr., etc.— B.B. infusible; on charcoal in R.F. becomes magnetic; with borax in O.F. gives a bead, which is yellow while hot and colorless on cooling ; if saturated, the bead appears red while hot and yellow on cooling ; in R.F. gives a bottle-green color, and if treated on charcoal with metallic tin, assumes a vitriol-green color. With soda on charco.al in R.F. is reduced to a gray magnetic metallic powder. Soluble in concentrated hydrochloric acid. HIS. — Distinguished from magnetite by its red streak, also from limonite by the same means, as well as by its not containing water ; from turgite by its greater hardness and by its not decrepitating B.B. It is hard ; and infusible. Obs. — This ore occurs in rocks of all ages. The specular variety is mostly confined to crys- t-alline or metamorphic rocks, but is also a result of igneous action about some volcanoes, aa at Vesuvius. Traversella in Piedmont ; the island of Elba, aiford fine specimens ; also St. Gothard, often in the form of rosettes \Eisenrose , and Cavradi in Tavetsch ; and near Limoges, France. At Etna and Vesuvius it is the result of volcanic action. Arendal in Norway, Long- ban in Sweden, Framont in Lorraine, Dauphiny, also Cleator Moor in Cumberland, are other localities. In N. America., widely distributed, and sometimes in beds of vast thickness in rooks of the Archaean age, as in the Marquette region in northern Michigan ; and in Missouri, at the Pilot Knob and the Iron Mtn. ; in Arizona and N*w Mexico. Some of the localities, interesting for their specimens, are in northern New York, etc.; Woodstock and Aroostook, Me.; at Hawley, Mass. ; at Pie'rmont, N. H. This ore affords a considerable portion of the iron manufactured in different countries. The varieties, especially the specular, require a greater degree of heat to melt than other ores, but the iron obtained is of good quality. Pulverized red hematite is employed in polishing metals, and also as' a coloring material. The fine-grained massive variety from England (bloodstone), showing often beautiful conchoidal fracture, is much used for burnishing metals. Red ochre is valuable in making paint. Martite is iron sesquioxide under an isometric form, occurring in octahedrons or dodeca- hedrons like magnetite, and suppo.sed to be pseudomorphous, mostly after magnetite. H. = 6-7. G. =4 -809^ -802, BrazU, Breith. ; 5 -80, Monroe, N. Y., Hunt. Lustre submetallic. Color iron-black, sometimes with a bronzed tarnish. Streak reddish-brown or purplish-brown. Fracture conchoidal. Not magnetic, or only feebly so. The crystals are sometimes imbed- ded in the massive sesquio.Kide. They are distinguished from magnetite by their red streak, and very feeble, if any, action on the magnetic needle. Found in Vermont at Chittenden; in the Marquette iron region south of L. Superior; Bass lake, Canada West; Digby Neck, Nova Scotia; at Monroe, N. Y. ; in Moravia, neaj Bchonberg^ in granite. MENACCANITE.* Ilmenite. Titanic Iron Ore. Titaneisen, Oenn. m^ Rhombohedral ; tetartohedral to the hexagonal type. R l\It ■=^ 85° 30' 270 DESCEIPnVE MINERALOGY. 470 50" (lioksch.), c = 1*384:58. Angles nearly as in hematite. Often , a cleavage jDarallel with the terminal plane, but probably due to planes of composition. Crystals usually tabular. Twins: twinning-plane ', sometimes producing, wlien repeated, a form resembling f. 468. Often in tliin_ plates or laminse ; massive ; in loose grains as sand. II. = 5-6. G.=r4;^5-5. Lustre siibmetallic. Color iroii^^black. Streak submetallic, powder black to brownish-red. Opaque. Fracture con- choidal. Influences slightly the magnetic needle. Comp., Var. — (Ti,Fe)203 (or hematite, with part of the iron replaced by titanium), the pro portion of Ti to Fe varying. Mosander assumes the proportion of FeO : TiOs to be alwaya 1:1, and that in addition variable amounts of FeOa are present in the different varieties. The extensive investigations of Rammelsberg have led him to write the formula like Mosan- der (FeO,TiO.>)+nFe03 (notice here that FeO,TiO..=ii03). This method has the advantage of explaining the presence of the magnesium, occurring sometimes in considerable amount, it replacing the iron (FeO). The first formula given requires the assumption of Mg^Oa. Friedel and Guerin have recently discussed the same subject (Ann. Ch. Phys., V., viii., 38, 187G). Sometimes contains manganese. The varieties recognized arise mainly from the proportions of iron to titanium. No satisfactory external distinctions have yet been made out. The following analyses will illustrate the wide range in composition : MgO 1-14=99 -89, Mosander. 1-33, AlOr, l-4G=98-50, Ramm. 13-71 =99 14, Ramm. Pyr., etc. — B.B. infusible in OF, although slightly rounded on the edges in R. F. With borax and salt of phosphorus reacts for iron in O.F. , and with the latter flux assumes a more or less intense brownish-red color in R.F. ; this treated with tin on charcoal changes to a violet-red color when the amount of titanium is not too small. The pulverized mineral, heated with hydrochloric acid, is slowly dissolved to a yellow solution, which, filtered from the undccomposed mineral and boiled with the addition of tin-foil, as.sumes a beautiful blue or violet color. Decomposed by fusion with sodium or potassium bisulphaie. Difif. — Resembles hematite, but has a submetallic, nearly black, streak. Ob.s. — Some of the principal European localities of this species are : Krageroe, Egersnnd, Arendal, Norway; Uddewalla, Sweden; Ilmen Mts. {ilmenite) ; Iserwiese, Riesengebirge (i«er- ine) ; Aschaffenburg ; Eisenach ; St. Cristophe {criclitonite). Occurs in Warwick, Amity, and Monroe, Orange Co., N. Y. ; also near EdenviUe ; at Ches- ter and South Royalston, Mass. ; at Bay St. Paul in Canada; also with labradorite at Chateau Richer. Grains are found in the gold sands of California. TiO, FeOs FeO MnO 1, Ilmen Mts,, Ilmenite 46*92 10-74 37-86 2-73 2. Snarum 10-03 77-17 8-52 - 3. Warwick, N, Y. 57-71 26-82 0-90 PEROFSKITE.* Isometric, Rose (fr. Ural). Habit cubic, with secondary planes incom- pletely developed ; in cubes, octahedi-ons, and cul)0-octahedrons, from .A.rkansas, Twins: twinning-})lane octahedral. Magnet Cove, Ark.; also like f. 276, p. 93, Achmatovsk. Cleavage : parallel to the cubic faces ratlier perfect. II. = 5-5. G.=4*02-4'04. Lustre metallic — adamantine. Color pale veilow, honey-yellow, orange-yellow, reddish-brown, grayish-black to iron- black. Streak colorless, grayish. Transparent to opaque. Double refmct- OXYGEN C0MP0TIND8. ANHYDROUS 0XIDE8. 271 Oomp.—(Ca+Ti)03=fi03 = Titanic oxide 59 4, lime 40-6=100. Pyr., etc. — In the forceps and on charcoal infusible. With salt of phosphorus in O.F. dis solves easily, giving a bead greenish while hot, which becomes colorless on cooling; in R.F. the bead changes to grayish-green, and on cooling assumes a violet-blue color, ^^itirely de- composed by boiling sulphuric acid. Obs. — Occurs at Achmatovsk. in the Ural ; in the valley of Zermatt ; at Wildkrenzjoch in tho Tyrol. Also at Magnet Cove, Arkansas. DesCloizeaux has found that the yellow crystals from Zermatt have a complex twinned structure, and are optically biaxial. Kokscharof, in his latest investigations, has shown that the Russian specimens also exhibit phenomena in polarized light analogous to those of biaxial crystals, though irregular. He proves, however, that crystallographically the crystals ex- amined by him were unquestionably isometric, and adds also that almost all the Russian •perofskitc crystals are penetration-twins. The latter fact explains the commonly observed striations on the cubic planes, as also the incompleteness in the development of the other forms. He refers the optical irregularities to the want of homogeneity in the crystals. Des- Cloizeaux speaks of inclosed lamellae of a doubly-refracting substance analogous to the para- site in boracite crystals (p. 176). Hydkotitanite. — A decomposition-product of perofskite crystals from Magnet Cove, Arkansas. Form retained but color clumged to yeUowiah-gray (Kcenig). (c) Compounds op Protoxides and Sesquioxides,* E,RO^(or RO+RO3). Spinel Group. Isometric {Octahedral), SPINEL. Isometric. Habit octahedral. Faces of octahedron sometimes convex. Cleavao-e : octahedral. ~Twins : twinning-plane 1. H. = S. G.=:3'5-4'l. Lustre vitreous ; spjendent — nearly dull. Color red of various shades, passing into bliieT^green, yellow, brown, and black ; occasionally almost white. Streak white. Transparent — nearly opaque. Fractnre conchoidal. 471 Oomp., Var — The spinels proper have the formula MgA104(=MgO -HAIO3), or in other words contain chiefly magnesium and aluminum, with the former replaced in part by iron (Fe), calcium (Ga), and man- ganese (Mn) ; and the latter by iron (Fe). There is hence a grada- tion into kinds containing little or no magnesium, which stand as distinct species, viz., Hercynite and Oafinite. MgAlO 4= Alumina 72. magnesia 28=100. i/' Var. 1. liubi/, or Magnesia Spinek — Clear red or reddish; transparent to translucent; sometimes subtranslucent. G. =3 '52-3 "58. Composition MgA10<, with little or no Fe, and sometimes chromium as a source of the red color. 2. Gejjlonite^ or Iron- Magnesia Spinel. Color dark-green, brown to black, mostly opaque or nearly so. G.=3'5-3'6. Composition MgA104 + Fe.V104. Sometimes the Al is replaced in part by Fe. 3. Pieoiite. Contains over 7 p. c. of chromium oxide. Color black. Lustre brilliant. G. =:4'08. The original was from a rock occurring about L. Lherz, called Lherzolite. Pyr., etc. — B.B. alone infusible; the red variety turns brown, and even black and opaque, as the temperature increases, and on cooling becomes first green, and then nearly colorless, and at last resumes the red color. Slowly soluble in borax, more readily in salt of phosphorus, with which it gives a reddish bead while hot, becoming faint chrome-green on * The compounds here considered are sometimea regarded as salts of the acide. HiROt, bbat is, as aluminates, ferrates, eta 272 DKSCKIPnTE MINEEAXOGT. cooling. The black varieties give reactions for iron with the fluxes. Solable with difficulty in concentrated sulphuric acid. Decomposed by fusion with sodium or potassium bisulphate. Diflf. — Distinguished by its octahedral form, hardness, and infusibility ; magnetite it attracted by the magnet, and zircon has a higher specific gravity. Obs. — Spinel occurs im.bedded in granular limestone, and with calcite in serpentine, gneisa, and allied rocks. It also occupies the cavities of masses ejected from some volcanoes, e.g.^ Mt. Somma. Fine spinels are found in Ceylon ; in Siam, as rolled pebbles in the channels of rivers Occur at Aker in Sweden ; also at Monzoni in the Fassathal. From Amity, N. Y., to Andover, N. J., a distance of about 30 miles, is a region of granulai limestone and serpentme, in which localities of spinel abound ; numerous about War%vick, and at Monroe and Cornwall. Franklin, Sterling, Sparta, Hafuburgh, and Vernon, N. J., are other localities. At Antwerp, Jefferson Co., N. Y. ; at Bolton and elsewhere in Mass. Hekctnite.— FeAlOi (or FeO+AlOs). Color black. Massive. Bohemia. >lj Jacobsite {Damour). — RRO4, or (Mn.Mg) (Fe,Mn)04. Color deep black. Occnrs in dis- / torted octahedrons (magnetic) in a crystalline limestone at Jacobsberg, Sweden. GAHNITE. Zinc Spinel. Isometric, In octahedrons, dodecahedrons, etc., like spinel. H. = 7'5-8. G.=:4r-4*6. Lustre vitreous, or somewhat greasy. Color dark green, gi-ajish-green, deep leek-green, greenish-black, bluish-black, yellowish- or grayish-brown ; streak grayish. Subtranslucent to opaque. Comp., Var — Znry04= Alumina 61 -3, oxide of zinc 387=100 ; with little or no magnesium. The zinc sometimes replaced in small part by manganese or iron (Mn,Fe), and the aluminum in part by iron (Fe). Var. 1. Automolite, or Zinc OaJinite ; with sometimes a little iron. G.=4'l-4-G. Colors as above given. 2. Dynluite^ or Zinc-Manganese- Iron GaJinite. Composition (Zn.Fe,Mn) (i\:l,Fe)04. Color yellowish-brown or grayish-brown. G. =4-4 6. Form the octahedron, or the same with truncated edges. 8. Kreittonite, or Zinc-fron Oahnite. Composition (Zn, Fe,Mg)(ril,Fe,04. Occurs in crystals, and granular massive. H.=7-8. G. =448-489. Color velvet to greenish -black ; powder grayish-green. Opaque. Pyr., etc. — Gives a coating of zinc oxide when treated with a mixture of borax and soda on charcoal. Otherwise like spinel. Obs — Automolite is found at Fahlun, Sweden ; Franklin, N. Jersey ; Canton mine, Ga. ; Dyduite at Sterling, N. J. ; Kreittonite at Bodenmais in Bavaria. MAGNETITE. Magnetic Iron Ore. Magneteisenstein, Magneteisenerz, Oerm. Isometric. The octahedron and dodecahedron the most common forms, 472 474 475 Achmatovak. Had dam. b'ig. 4:75 is a distorted dodecahedi'on. Cleavage : octahedral, perfect tc OXYGEN COMPOUNDS. — ANHTDKOUS OXIDES. 273 imperfect. Dodecahedral faces commonly striated parallel to the longer diagonal. Twins : twi^v ng-plane, 1 ; also in dendrites, branching at angles of 60° (f. 277, p. bOy Massive, structure granular — particles of various sizes, sometimes impalpable. H. = 5-5-6*5. G.= 4^9-5-2. Lustre metallic — snbmetallic. Color iron black ; lli-eak black. Opaque ; but in mica sometimes transparent or nearly so ; and varying from almost colorless to pale smoky-brown and black. Fracture subconcboidal, shining. Brittle. Strongly magnetic, sometimes possessing polarity. Comp., Var.— FeFe04 (or Fe,04)=FeO-HFe03=Oxygen 27-6, iron 73-4=100 ; or iron ses- quioxide 68"97, iroa protoxide 3103=100. The iron sometimes replaced in smaU part by magnesium. Also sometimes titaniferous. * From the normal proportion of Fe to Fe, 1 : 1, there is occasionally a wide variation, and thus a gradual passage to the sesquioxide FeOs ; and this fact may be regarded as evideucd that the octahedral FeOs, martite, is only an altered magnetite. Pyr., etc. — B. B. very difficultly fusible. InO.F. loses its influence on the magnet. With the fluxes reacts like hematite. Soluble in hydrochloric acid. Dlflf. — Distinguished from other members of the spinel group, as also from garnet, by its being attracted by the magnet, as well as by its high specific gravity. Also, when massive, by its black streak from hematite and limonite. Obs. — Magnetite is mostly confined to crystalline rocks, and is most abundant in metamoi - phic rocks, though found also in grains in eruptive rocks. In the Archsean rocks the beds are of immense extent, and occur under the same conditions aS those of hematite. It is an ingre- dient in most of the massive variety of corundum called emery. The earthy magnetite is found in bogs like bog-iron ore. Extensive deposits occur at Arendal, Norway ; Dannemora and the TJiberg in Smaoland ; in Lapland. Fahlun in Sweden, and Corsica, afford octahedral crystals. In N. America, it constitutes vast beds in the Archaean, in the Adirondack region, in Northern N. York ; also in Canada ; at Cornwall in Pennsylvania, and at Magnet Cove, Arkansas. Also found in Putnam Co. (Tilly Foster Mine), N. Y., etc. In Conn., at Haddam. In Penii., at Cliester Co. • in mica at Pennsbury. In California, in Sierra Co. ; in Plumas Co., and elsewhere. In iV". Scotia, Digby Co., Nichol's Mt. Magnesiofekrite {mngnoferrite). — MgFe04. In octahedrons; resembling magnetite Vesuvius. FRANK LINTTB. Isometric. Habit octaliedral. Cleavage: octahedral, indistinct. Alsc massive, coarse or fine granular to compact. ' H.=5;5-6-5. G.=5:069. Lustre metallic. Color iron-black. StrealN dark reddish-brown. Opaque. Fracture couchoidal. Brittle. Acts slight!) on the magnet. Comp. — (Fe,Zn,Mn) (Fe,MD)04, or corresponding to the general formula of the spun;v group, though varying much in relative amounts of iron, zinc, and manganese. Analysis SterUng Hill, N. J., JFeOa 67-42, AIO3 0-G5, FeO 15 •(J5, ZnO 6-78, MnO 9-53=10012, Seyms Q. ratio for R : R=l : 1 nearly. In a ci-ystal from Mine Hill, N. J., Seyms found 4" 44 p. c, MnOs. The evolution of chlorine in the treatment of the mineral is attributed by v. Kobell to the presence of a little MnOa (0.80 p. c.) as mixture, which Rammelsberg observes may have come from the oxidation of some of the protoxide of manganese. Pyr., etc.— B.B. infusible. With borax in O.F. gives a reddish amethystine bead (man- ganese), and in R.F. this becomes bottle-green (iron). With soda gives a bluish-green man- ganate, and on charcoal a faint coating of zinc oxide, which is much more marKed when a mixture of borax and soda is used. Soluble in hydrochloric acid, with evolution of a small amount of chlorine. Difif.— Resembles magnetite, but is only slightly attracted by the magnet; it also leacti for zinc on charcoal B.B. 18 274 DESOJKIPnVE MINERALOGT. Obs. — Occurs in cubic crystals near Eibach in Nassau ; in amorphous masses at Altenbeig, near Aix la Chapelle. Abundant at Hamburg, N. J., near the Franklin furnace; also at Stirling Hill, in the same region. CHROMITE.* Chromic Iron. Chromeisenfltein, Germ. Isometric. In octahedrons. Commanly massive ; stnicture fine granu- lar or compact. H. = 5-5. G.=4-321-4-568. Lustre submetallic. Streak brown. Color between iron-black and brownish-black. Opaque. Fracture uneven. Brittle. Sometimes magnetic. Comp — Fe^rOi, or (Fe,Mg,Cr) (Al,Fe,^r)04. Fe€r04=Iron protoxide 32, chromium ses- quioxide 68=100. Magnesia is generally present, and in amounts varying from 6-24 p. c. Pyr., etc. — B. B. in O. F. infusible ; in R. F. slightly rounded on the edges, and becomes magnetic. "With borax and salt of phosphorus gives beads, which, while hot, show only a reaction for iron, but on cooling become chrome-green ; the green color is heightened by fusion on charcoal with metallic tin. Not acted upon by acids, but decomposed by lusicn with potassium or sodium bisulphate. Diff. — Distinguished from magnetite by the reaction for chromic acid with the blowpipe. Obs. — Occurs in serpentine, forming veins, or in imbedded masses. It assists in giving the variegated color to verde-antique marble. Also occurs in meteorites. Occurs in Syria ; Shetland ; in Norway ; in the Department du Var in France ; in Silesia and Bohemia ; in the Urals; in New Caledonia. At Baltimore, Md., in the Bare Hills ; at Cooptown. In Pennsylvania, in Chester Co. ; at Wood's Mine, near Texas, Lancaster Co. , etc. Chester, Mass. In California, in Monterey Co., etc. This ore affords the chromium oxide, used in painting, etc. The ore employed in England is obtained mostly from Baltimore, Drontheim in Norway, and the Shetland Isles. CniiOMPicOTiTE (Petersen). — A maguesian chromite. Color black. New Zealand. Y Uraninite* (Pitchblende ; Uranpecherz, G'erm.).— UsOelUOa-hSUOs). Saxony, etc Massive. Black. CHRTSOBERYL. 476 477 Orthorhombic. /A I=z 129° 38', M-'i = 129° 1 ' ; c'.h:d = 1-2285 : 2-1267:1. -i-^Al =136^52',*-*A 2-2 = 128° 52', i-l A \-l = 120° 7'. Plane i-l vertically striated ; and sometimes also i-i, and other verti- cal planes. Cleavage : 1-i quite distinct; i-i imperfect; i-l more so. Twins : twiiming-plane 3-*, as in f. 477 (see p. 97), made up of 6 parts by the crosshig of 3 ci-ystals. H.=8-5. G.=3-5-3-84. Lustre vitreous. Color asparagus-green, grass-green, emerald-green, green- ish-white, and yellowish-green, •ometimes raspberry or columbine-red by transmitted light. Streak uncol- ored. Transparent— translucent. Sometimes a bluish opalescence inter- nally. Fracture conchoidal, uneven Norway, Me. Alexandrite. OXYGEN COMPOUNDS. — ANHTDR0U8 OXmES. 275 Var. 1. Ordinary. — Color pale green, being colored by iron. G.— 3.597, Haddam ; 3 ■734 Brazil; 3'689, Ural, Eose ; 3'835, Orenburg, Kokscharof. 2. Alexandrite. — Color emerald- green, but columbine-red by transmitted light. G. =3 "644, mean of results, Kokscharof. Supposed to be colored by chrome. Crystals often very large, and in twms, like f. 477, either six-sided or six-rayed. Comp. — Be AlOj— Alumina 80 2. glucina 19'8=100. Iron is also often present, though not in the transparent varieties. Isomorphous with chrysolite. Pyr., etc. — B.B. alone unaltered; with soda, the surface is merely rendered dull. With borax or salt of phosphorus fuses with great diflSculty. With cobalt solution, the powdered mineral gives a bluish color. Not acted upon by acids. Diff. — D'stinguished by its extreme hardness, greater than that of topaz ; and its infusi bility ; also characterized by its tabular crystallization, in contrast with beryl Obs. — In Brazil and also Ceylon ; at Marchendorf in Moravia ; in the Ural ; in the Mouma Mts,, Ireland; at Haddam, Ct. ; at Norway, Me. When transparent, and of sufficient size, chrysoberyl is cut with facets, and forms a beauti- ful yellowish-gTeen gem. If opalescent, it is usually cut en eabochon. (d) De UTOXIDES, RO, Hutile Group. Tetragonal. OASSITERITE. Tin Stone. Zinnstein, Zinnerz, Oerm. Tetragonal. O A 1-i = 146° 5' ; c = 0-6724. 1 Al, pvr., = 121° 40' ; /Al = 133° 34'; 1-i M-i, pyr., = 133° 31'. _ Cleavage: 7 and i-i hardly distinct. Twins: f. 478, twinning-plane 1-i; producing often complex forms through the many modifying planes ; sometimes repeated parallel to all the eight planes 1-i; also f. 480, a raetagenic twin. Often in reniform shapes, structure fibrous divergent ; also massive, granular or impalpable. 479 H.=6-7. G.=6-4-7'l. Lustre adamantine, and crystals usually s pleu; dent. TJolor brown or black ; sonietrines"Ted, gray, white, or yellow. Streak white, grayish, brownish. Nearly transparent — opaque. Fracture subconchoidal, uneven. Brittle. Var. — 1. Ordinary., Tin-stone. In c^Btals and massive. G. of ordinary cryst. 6 96; of colorless, from Tipuani R., Bolivia, 6-832, Forbes. 2. Wood Tin (Holz-Zinn, Germ.). Id botrvoidal and reniform shapes, concentric in structure, and radiated fibrous internally 276 DESCRimVE MINERAIOGT. although very compact, with the color brownish, of mixed shades, looking somewhat like dn wood in its colors. G. of one variety 6 '514. Stream tin is nothing but the ore in the state of sand, as it occurs along the beds of streams or in the gravel of the adjoining region. It has been derived from tin veins or rocks, through the wear and decomposition of the rocka and transportation by water. Comp.— SnOo = Tin 786, oxygen 21-4=100. Pyr., etc. — B.B. alone unaltered. On charcoal with soda reduced to metallic tin, and gives a white coating. With the fluxes sometimes gives reactions for iron and manganese, and more rarely for tantalic oxide. Only slightly acted upon by acids. Diff. — Distinguished by its high specific gravitj', ils infusibility, and by its yielding metallic tin B.B. from some varieties of garnet, sphalerite, and black tourmaline, to which it has ■ome resemblance. Specific gravity (6 '5) higher than that of rutile (4). Obs. — Tin ore is met with in veins traversing granite, gneiss, mica schist, chlorite or clay Bchist, and porphyry. Occurs in Cornwall ; in Devonshire ; in Bohemia and Saxony ; at Limoges ; also in G-alicia ; Greenland ; Sweden, at Finbo ; Finland, at Pitkaranta. In the E. Indies ; in Victoria and New South Wales ; in large quantities in Queensland. In Bolivia, S. A. ; in Mexico. In the United States, rare : in Maine, at Paris ; in N. ITamp., at Lyme ; in California^ in San Bernardino Co. ; in IdaJio, near BoonviUe. RUTILE.* Tetragonal. O A 1-* = 147° 12^', c = 0-6442. 1 A 1, pyr., = 123° 7^', /a 1 = 132° 20'. Cleavage : / and i-i, distinct ; 1, in traces. Yertical planes usually striated. Crystals often acicular. Twins: (1) twinning-plane 1-i (see p. 94). (2) 3-^, making a wedge-shaped crystal consisting of two individuals. (3) 1-i and 3-^ in the same crystal (fr. Magnet Cove, Hesseu- berg). Occasionally compact, massive. 481 482 483 Graves Mtn. , Ga. H. = 6-6'5. G.=4'18-4'25. Lustre rnetallic- adamantine. Color icd- dish-brown, passing into red; sometimes yellowish, bluish, Molet, black ; rarely grass-green. Streak pale bro^vn. Subtransparent — opaque. Irac- ture subconchoidal, uneven. Brittle. Comp., Var — Titanic oxide, TiOj = Oxygen 39, titanium 61 = 100. Sometiuies a li< de iron is present. Pyr., etc — B.B. infusible. With salt of phosphorus gives a colorless bead, which in E F assumes a violet color on cooling. Most varieties contain iron, and give a browni.sh-;vellow or red bead in R.F., the violet only appearing after treatment of the bead with metallic tin on charcoal. Insoluble in acids ; made soluble by fusion with an alkali or alkaline carbonate. The solution containing an excess of acid, with the addition of tin-foil, gives a beautifol vioJet-color when concentrated. OXYGEN COMPOUNDS. — ANHYDK0TJ8 OXTOES. 277 Diflf. (Tharacterized by its peculiar sub-adamantine lustre, and brownish-red color. Diflfers ftom \ armaline, vesuviamite, augite in being entirely unaltered when heated alone B.B. Specif.<^ gravity about 4, cassiterite 60. Obb.- -Rutile occurs in granite, gneiss, mica slate, and syenitic rocks, and sometimes in graDalp,'- limestone and dolomite. It is generally found in imbedded crystals, often in masses of qcartz or feldspar, and frequently in acicular crystals penetrating quartz. Very commonly implanted in regular position upon crystals of hematite, as from Cavradi in the Tavetschthal. Occurs in Norway; Finland ; Saualpe, Carinthia; in the Urals ; in the Tyrol ; at St. Gothard near Freiberg ; at Ohlapian in Transylvania. In Maine, at Warren, In Vermont, at Waterbury and elsewhere. In Mass. , at Barre : Shelbume; Sheffield. In Conn., at Lane's mine, Monroe. In N. York, in Orange Co.; Edenville ; Warwick. In Perm., Chester Co. In iV. Car., at Crowder's Mountain. In Georgia, in Habersham Co. ; in Lincoln Co., at Graves' Mountain. In Arkansas, at Magnet Cove. Titanium oxide is employed for a yellow color in painting porcelain, and also for giving tb" reqiiisite tint to artificial teeth. OOTAHBDRITE.* Anatase. Biunenthal. Tetragonal. Al-i = 119^ 22'; c = 1-77771. Commonly octahedral or tabular- 1 A 1, pyr., = 97° 51'. /Al = 158°18'. 484 Cleavage: 1 and O, per- fect. H.=5-5-6. G.=3-82- 3-95 ; sometimes 4-ll-4'16 after heating. Lnstre metal lic:adainantine. Col- or various shades of brown, passing into indigo-blne, and black ; greenish-yellow by transmitted light. Streak uncolored. Fracture snbconchoidal. Brittle. Comp. — Like rutile and brookite, pure titanic oxide. Pyr., etc. — Same as for rutile. Obs. — Abundant at Bourg d'Oisans, in Dauphiny ; also iu the Bin- ■ nenthal (including here Kenngott's wiseri?ie, f. 484, as shown by Klein. Jahrb.Min.. 1875, 337); at Pfitsch Joch, Tyrol; near Hof in the Fichtelgebirge ; Norway; the Urals; in Devonshire, near Tavistock ; at Tremadoc, in North Wales ; in Cornwall ; in Brazil in qviartz. In the U. States, at Sraithfield, R. I. y* Hausmannite. — Mn304=2MnO,Mn02. Tetragonal, OM-t =130° 25'. Color brownish- black. Thuringia ; Harz, etc. V^ Braunite.— 2(2MnO,MnOa)+MnO,,SiOj. Tetragonal, Al-i =135° 26'. Color dark brownish-black. Thuringia ; Norway, etc. » rMmiOM (Mennige, Oerm.). —PbtOi=F\}02+2PhO. Badenweiler; Wythe Co., Va., etc. BROOKITE.* Orthorhombic (?). /A 7=99° 50' (-100» 50'): 0Al-l = 13V 42'; h.b:d = 1-1620 : 1-1883 : 1. Cleavage : /, indistinct ; 0, still more so. H.=5-5-6. G. =4-12-4-23, brookite; 4-03-4-085, arkansite. Hair-brown, vcllowish, or reddish, with metallic adamantine lustre, and ti-anslucent 2"3 DESCKIPnVE MINERALOGY. (brookite) ; also ircn-black, opaque, and subraetallic (arkanEite). Streal iincolored — grayish, yellowish. Brittle. 487 488 Arkansas. //- EUenville, N. T. " y Miask, Ural. Comp. — Pure titanic oxide, TiOs, like rutile and octaliedrite. Pyr., etc. — Same as for rutile. Obs. — Brookite occurs at Bourg d'Oisans in Dauphiny ; at St. Gothard; in the Urals, near Miask ; in thick black crystals {arkan-nte f. 486) at Mag-net Cove, Arkansas, sometimes altered to rutile \ij paramorphism ; at EUenville, Ulster Co., N. Y. ; at Paris, Maine. Schrauf has announced {Atlas Min., Reich. IV.) that he has found brookite to be monoclinic (and isomorphous with wolframite). He distinguishes three types having different axial relations. The measurements of v. Rath, however, seem to show that in part it must be orthoTJiomiic. EUMANiTE. — From Chesterfield, Mass., may be identical with brookite. PYROLUSITE.* Polianite. Orthorhombic. 489 1 ; T ' I/\I=93'' 40', Oa1-1 = U2° IV; c: b : a = 0-776 : 1*066 : 1. cleavage /and i-i. Also columnar, often divergent ; also granular massive, and frequently in reniform coats. Often soils. H.=2-2-5. G.=4-82. Turner. Lnstre metallic. Color iron-black, dark steel-gray, sometimes bluish. Streak black or bluish-black, sometimes snbmctallic. Opaque. Rather brittle. Comp. — Mn02=Manganese 63-2, oxygen 36-8=100. Pyr., etc. — B.B. alone infusible; on charcoal loses oxygen. A manganese reaction with borax. Affords chlorine with hydrochloric acid. Diff. — Hardness less than that of psiiomelane. Differs from iron ores in its reaction foi manganese B. B. Easily distinguished from psiiomelane by its inferior hardness, and usually by being crystalline. Obs. — Occurs extensively at Elgersberg near Ilmenau in Thuringia ; at Vorderehrensdorf in Moravia ; at Platten in Bohemia, and elsewhere. Occurs in the United States in Vermont, at Brandon, etc. ; at Conway. Mass. ; at Winchester, N. H. ; at Salisbury and Kent, Conn. In California, on Red island, bay of San Francisco. In New Brunswick, near Bathurst. In Nova Scotia, at Walton; Pictou, etc. Pyrolusite and manganite are the most important of the ores of manganese. Pyrolusite parts with its oxygen at a red heat, and is extensively employed for discharging the brown and green tints of glass. It hence received its name from -vp, fire, and avu, to wash. Cbedkerite. — CusMnaOs, or SCuO-j-ZMnOa. Foliated. Color black. Thuringia. OXYGEN COMPOUNDS. — nYDKOCS OXIDES. 279 B. HYDROUS OXIDES. TURGITE. Compact fibrous and divergent, to massive ; often botryoidal and sta- lactitic like limonite. Also earthy, as red ochre. IL=5-6. G.=3-56-3-74, frojn Ural; 4-29-4-49, fr. Hof; 4-681, fr. Hoihausen ; 4"14, fr. Salisbury. Lusti-e snbmetallic and somewhat satin- like in the direction of tlie fibrous structure; also dull earthy. Color reddish-black, to dark red ; bright-red when earthy ; botryoidal surface often lustrous, like much limonite. Opaque. Comp. — HjFej07=Iron sesquioxide 94 7, water 53:=100. Pyr., etc. — Heated in a closed tube, flies to pieces in a remarkable manner ; yields water. Otherwise like hematite. Diff. — Distiuguislied from hematite and limonite by its superior hardness, the color of its streak, and B.B. its decrepitation. Obs. — A very common ore of iron. Occurs at the Turginsk copper mine near Bosgolovsk, in the Ural ; near Hof in Bavaria, and Siegeu in Piiissia ; at Horhausen. In the U. S. it occurs at Salisbury, Ct. 490 DIASPORE. Orthorhombic. /A /= 93° 42f', 6> A 14=147° 12^'; c 0-64425 : 1-067 : 1. i-lM-l = 121^ 7V, «-t A 1-5 = 104° 14^', ^-i A 1 = 116° 54i'. Crystals usually thin, flattened garallel to i-l] sometimes acicular; commonly implanted, ileavage : i-l eminent ; ^-2 less perfect. Occurs foliated massive and in thin scales ; Bometimes stalactitic. II. = 6*5-7. G. = 3"3-3*5. Lusti-e biilliant and pearly on cleavage-face; elsewhere vitreous. Color whitish, giayish- white, greenish-gray, hair-brown, yellowish, to colorless ; sometimes violet-blue in one direction, reddish plumb-blue in another, and pale asparagus-green in a third. When thin, translucent — subtranslucent. Very brittle. Oomp. — Ho A104= Alumina 85'1, water 14"9 = 100 ; a little phosphorus pentoxide is often present. Pyr., etc. — In the closad tube decrepitates strongly, separating into pearly white scales, and at a high temperature yields water. The variety from Schemnitz does not decrepitate. Infus'ble ; with cobalt solution gives a deep blue color. Some v-irieties react for iron with t'he fluxes. Not attacked by acids, but after ignition becomes soluble in sulphuric acid. Diff. — Distingui-ihed (B.B.) by its decrepitation and yielding water ; as also by the reaction for alumina with cobalt solution. Resembles some varieties of hornblende, but is harder. Ob3. — Commonly found with corundum or emery. Occurs in the Ural; at Scbeinnitz; at Broildbo near Fahlun; in Switzerland ; in Asia Minor, and the Grecian islands ; in Chesfcei Co., Pa. ; at the emery mines of Chester, Mass. ; N. Carolina. Dinspore was named by Haiiy from diaan-Eipu^ to scatter, alluding to the usua] decrepitation before the blowpipe. 280 DESCRIPTIVE MINERALOGY. a&. GOTHITE. OrthurhomVc. /A /= 94° 52' (B. & M.) ; 6> A l-l = 146° 33' ; c : b : d = 0"66 : 1-089 : 1. In prisms longitudinally striated, and 491 often flattened into scales or tables parallel to the shorter diagonal. Cleavage : bi-achydiagonal, \ery perfect. Also fibrons ; foliated or in scales; massive; reniform ; stalac- titic. II. = 5-5*5. Gr.=4*0-4*4. Lnstre imperfect adamantine. Color yellowish, reddish, and blackish-brown. Often blood- red by transmitted light. Streak brownish-yellow — ochre- yellow- Var. — 1. In thin scale-like or tabular crystals, usually attached by one edge. 2. In acicular or capillary (not flexible) crystals, or slender prisms, often radiately grouped : the Needle-lronsloiie (Nddelehenstein). It passes into (b) a variety with a velvety surface : the Pnihramite {Sammet blende) of Przibram is of this kind. Other varieties are columnar or fibrous, scaly-fibrous, or feathery columnar; compact massive, with a flat con- choidal fracture ; and sometimes reniform or stalactitic. Comp.— HoFe04=H6Fe06-h2Fe03-Iron sesquioxide 899, water 10-1 = 100. Pyr., etc. — In the closed t\ibe gives off water and is converted into red iron sesquioxide. With the fluxes like hematite ; most varieties give a manganese reaction, and some treated in the forceps in O.F.. after moistening in sulphuric acid, impart a bluish-green color to the flame (phosphoric acid). Soluble in hydrochloric acid. Obs. — Found with the other iron oxides, especially hematite or limonite. Occurs at Eiser feld ; in Nassau ; at Zwickau in Saxony ; in Cornwall ; in Somersetshire, at the Providence iron mines. In the U. States, near Marquette, L. Superior; in Perm., near Easton; in California, at Bums Creek, Mariposa Co. Named Oothite after the poet-philosopher Gothe; and PyrrJiosiderite from -vppog, Jire-redy and GidTjpog, iron. MANGANITE. Orthorhombic. 7 A /= 99= 40', A l-l = 147° 9^' ; c\l\a = 0-6455 : 1'185 : 1. Twins: twinning-plane \-l (f. 296, p. 96). Cleavage: i-l very perfect, 7 perfect. Crystals longitudinally striated, and often gronped Id bundles. Also columnar; seldom granular ; stalactitic. II. =4. G.=4-2-4-4. Lustre submetallic. Color dark steel-gray — iron- black. Streak reddish-brown, sometimes nearly black. Opaque; minute splinters sometimes brown by transmitted light. Fracture uneven. Comp.— H.Mn04=H6Mn06-t-2Mn03=Manganese sesquioxide 89-8 (=Mn 62-5, O 27-3). water 10 2=100. Pyr., etc. — In the closed tube yields water ; otherwise like braunite. Obs. — Occurs in veins traversing porphyry, at Ilefeld in the Harz ; in Thuringia ; Undenaes in Sweden ; Christiansand in Norway ; Cornwall, at various places ; also in Cumberland, Devonshire, etc. In Nova Scotia, at Cheverie, etc. In New Brunswick, at Shepody moun- tain, Albert Co., etc. LIMONITE. Brown Hematite. Brauneisenstein, Oerm. Usually in stalactitic and botryoidal or raammillary forms, having a fibrouB or subfibrous structnre; also concretionary, massive; and occasionally earthy. OXYGEN COMPOUNDS. — HYDROUS OXIDES. 281 H.=5-5*5. G.= 3-6-4. Lnstre silky, often subraetallic ; sometimes dull uiid earthy. Color of surface of fracture various shades of brown, com- monly dark, and none bright ; sometimes with a nearly black varnish-like exterior; when earthy, brownish-yellow, ochre-yellow. Streak yellowish- hrown. Var.- (1) Compact. Submetallic to silky in lustre : often stalactitic, botryoidal, etc. (2J Ochreous or earthy, brownish-yellow to ochre-yellow, often impure from the presence of clay, sand, etc. (8) Bog ore. The ore from marshy places, generally loose or porous in texture, often petrifying leaves, wood, nuts. etc. (4) Brown day -ironstone, in compact masses, often in concretionary nodules, having a brownish-yellow streak, and thus dLstinguishable from the clay-ironstone of the species hematite and siderite; it is sometimes (a) pisoUtio, or an aggre- gation of concretions of the size of small peas (Bohnerz, Germ.); or {_b) oolitic. Comp. — HeFei09=H6Fe06 + Fe03=Iron sesquioxide 83-6, water 14-4=:100. In the bog ores and ochres, sand, clay, phosphates, manganese oxides, and humic or other acids of organio origin are very common impurities. Pyr., etc. — Like gothite. Some varieties give a skeleton of silica when fused with salt ot phosphorus, and leave a siliceous residue when attacked by acids. Difif. — Distinguished from hematite by its j'ellowish streak, inferior hardness, and its reac- tion for water. Does not decrepitate, B.B., like turgite. Obs. — Limonite occurs in secondary or more recent deposit?, in beds associated at times with barite, siderite, calcite, aragonite, and quartz ; and often with ores of manganese ; alsu as a modern marsh deposit. It is in all cases a result of the alteration of other ores, through exposure to moisture, air, and carbonic or organic acids ; and is derived largely from the change of pyrite, siderite, magnetite, and various mineral species (such as mica, augite, horn- blende, etc. \ which contain iron in the protoxide state. Abundant in the United States. Extensive beds exist at Salisbury and Kent, Conn. , also in the neighboring towns of N. Y. , and in a similar situation north; at Richmond and Lenox, Mass. ; in Vermont, at Bennington, etc. Limonite is one of the most important ores of iron. The pig iron, from the purer varieties, obtained by smelting with charcoal, is of superior quality. That yielded by bog ore is what is termed cold short, owing to the phosphorus present, and cannot therefore be emploj'ed in the manufacture of wire, or even of sheet iron, but is valuable for casting. The hard and compact nodular varieties are employed in polishing metnllic buttons, etc, Mel.\nosideritk. — Near limonite, but containing 7-39 p. c. SiO.., perhaps as an impurity. Cooke regards it as a very basic silicate of iron. G. =3*39. Westchester, Penn. Xanthosiderite.— H4Fe05=Fe03 816, HoO 18-4=100; or HaFeOa (Ramm.). In fine needles. Color yellow, brown. Ilmenau ; the Harz. Beauxite. — Occurs in concretionary grains. Color whitish to brown. Composition doubt- ful, perhaps Al(Fe)03+2aq. Beaux, near Aries, France ; near Lake Wochein, Styxia (loochei- nite) ; French Guiana. BRUCITE. Rhombohedral. RhR-S^"" 22^', 6^A^ = 119° 39^'; ci= 1-52078 (Hessenberg). Crystals often broad tabular. Cleavage: basal, eminent 492 493 Low's Mine, Texas. Wood's Mine, Texas. folia easily separable, nearly as in gypsum. Usually foliated massive Also fibrous, fibres separable and elastic. 282 DESCRIPTIVE MINERALOGY. H. = 2*5. G. = 2-35-2-44. Lustre pearly on a cleavage-face, elsewhere between waxy and vitreous ; the fibrous silky. Color white, inclining to ray, blue, or green. Streak white. Translucent — subtranslucent. SectiJe. hin laminae flexible. I' Oomp. — HnMgOa=Magne8ia 69, water 31 = 100. Var. — 1. Foliated. 2. Fibrous ; called nemnlite, containing 4 or 5 p. c. of FeO. Pyr., etc. — In the closed tube gives off water, becoming opaque and friable, sometimes turning gray to brown. B.B. infusible, glows with a bright light, and the ignited mineral reacts alkaline to test paper. With cobalt solution gives the violet-red color of magnesia. The pure mineral is soluble in acids without effervescence. Diif.— Distinguished by its infusibility. Differs from talc in its solubility in acids. Obs. — Brucite accompanies other magnesian minerals in serpentine, and has also been found in limestone. Occurs at Swinaness in Unst, Shetland Isles ; in the Urals ; at Goujot in France ; near Filipstadt in Wermland. It occurs at Hoboken, N. J. ; in Richmond Co. , N. Y. ; at Brewster, N. Y. ; at Texas, Pa. The fibrous variety {nemalite) occurs at Hoboken, and at Xettes in the Vosges. GIBBSITB. Monoclinic (DesCl.). In small hexagonal crystals wi';h replaced lateral edges. Planes vertically striated. Cleavage : basal or eminent. Occa- sionally in lamello-radiate spheroidal concretions. Usually stalactitic, or small mammillaiy and incrusting, with smooth surface, and often a faint fibrous structure within. H.=2-.5-3-5. G. = 2-3-2-4. Color white, grayish, greenish, or reddish- white ; also reddish-yellow when impure. Lustre of O pearly; of other faces vitreous; of surface of stalactites faint. Translucent; sometimes transparent in crystals. A str(>ng argillaceous odor when breathed on. Tough. Var. — 1. In crystals: the original %(frar^.''4'<5. 2. Stalactitic; gibbsite. Comp.—HaAlOe^Alumina 65-5, water 34-5 = 100. Pyr., etc.— In the closed tube becomes white and opaque, and yields water. B.B. infusible, whitens, and does not impart a green color to the flame. With cobalt solution gives a deep« blue color. Soluble in concentrated sulphuric acid. Diff. -Resembles chalcedony in appearance, but is softer. Obs. — The crystallized gibi)site occurs near Slatoust in the Ural; at Gumuchdagh. Asia Minor; on corundum at UnionviUe, Pa.; in Brazil. The stalactitic occurs at Richmond, Mass.; at the Clove mine. Duchess Co., N. Y.; in Orange Co., N. Y. Rose's hydrargillite (Urals, 1830) is identical with gibbsite (Ton-ey, 1822), and must receive this name. An uncertain mineral from Richmond afforded Hermann 38 p. c. of phosphoric acid, but a phosphate, if it really occui-s there, is not gibbsite. PYROCniioiTE.— H2MnOo=Manganese protoxide 79-8, water 202=100. Foliated. Color white. Mine of Paisberg. Filipstadt, Sweden. Hydrotalcite from Snarum, Norway, and Volknerite from the Urals, contain alumina, magnesia, and water with more or less carbon dioxide. Probably mixtures, containing brucite, gibbsite, etc. Hougiitte from Oxbow and Rossie, N. Y., is a similar mineral derived from the alteration of spinel. Namaqualite (Church). A related mineral; from Namaqualand, So. Africa. ^ ^(J^^ PSILOMELANE.* Massive and botryoidal. Reniform. Stalactitic. H.=5-6. G.=3-7-4-7. Lustre submetallic. Streak brownish-black, shining. Color iron-black, passing into dark steel-gray. Opaque. OXYGEN COMPOUNDS. — HTDROUS OXIDES. 283 Oomp.— Somewhat doubtful. Contains manganese oxide, with varying amounts of baryta, and potash (lithia), and also water. General formula, according to Rammelsberg, R608=B Al4 = 105° 35'; c: 3 : ^ = 3'5S68 : 2*5365 : 1. Often in rectanig^nlar plates with the lateral edges bevelled, and in aclcular rhombic prisms. Cleav- age: /, highly perfect, easily obtained. Also massive; structure lamellar, columnar, granular. H. = 2*5-3. G. = 5'566, crystals from Braunsdorf. Lustre adamantine, i-l often pearly ; shining. Color snow-white, occasionally peach-blossom red, and ash-gray to brownish. Streak white. Translucent — subtrans- parent. Comp.—Sb303= Oxygen 16-44, antimony 83-56=100. Ob-!. — Found at Przibram in Bohemia; at Felsobanya in Hungary; Braunsdorf in Saxony. Also at South Ham, Canada East. SENARMONTiTE.'ii— Same composition as the above, but crystallizes in isometric octahe- drons. G. =5 "2-5 -3. Perneck, Hungary ; Cornwall; Haraclas in Algeria ; S. Ham. Canada. Claudetite ; Arsen ot.ite. — Both AsoOs. The lormer is orthorhombic, the latter iso- metric. They thus correspond to the two forms of Sb.Oa (see above). Claudetite (G. =3-8o) occurs in thijn plates at the San Domingo mines, Portugal. ArsenoUte [(i. = 'd-(j^ii) occmxs usually in capillary crystals, also stalactitic ; earthy. Andreasberg ; JoachiTisthal ; Corn- wall ; Ophir mine, Nevada ; California. BiSMiTE (Wismuthocker, Ge?*m ). — BijOs. Occurs massive, earthy. Schneeberg; Joachims thai; Cornwall. Karelinite. — 3BiO+BiS. Massive. Color lead-gray. G. =6'60. Savo- dinsk mine in the Altai. MoLYBDiTE (Molybdanocker, Germ.). — Composition M0O3. In radiated crystallizations, as an incrustation, etc. Occurs with molyljdenite. At Westmoreland, New Hampshire ; Chester, Penn. ; Virginia City, Nevada. Ilsemannite, near the above. Bleiberg. Carinthia. TuNGSTiTE. — WOs. Pulverulent and earthy. Cornwall; Monroe, Ct. Meymacitk (Carnot). — A hydrated tungstite. Meymac, Correze. Kermesite (Anbimonblende, Crenw.).— Composition SbiS20=2SboS3 + Sb203. In capillar; crystals. Color cherry-red. Braunsdorf , Saxony ; Allemont; South Ham, Canada East. Cervantite. — Sb02 = Sb203 + Sb,06. Color yellow. Results from alteration of etibnite. Spain ; Tuscany ; Hungary, etc. ; South Ham, Canada. 3. OXIDES OF THE Carbon-silicon Group, Series II. QUARTZ.* Rhombohedral, and for the most part heraihedral to the rhombohedron (or tetartohedral to the hexagonal prism). KhE:^ 94° 15', O h li = 128'* 13' ; c == 1-0999. t A 2-2 :^ 142° 2^ R A -1, ov. *, ^ 103" 34', ^ A -1, adj., == 133° 44', H A i, ov. 2-2, ^ 113° 8'. Clea^vagc : K^ —1, and i vei'y indis- tinct: sometimes effected by plunging a heated crystal in cold water. Crj^stals sometimes very short, but general habit prismatic ; the crystals OXYGEN COMPOUNDS SILICA. '285 much elongated, sometimes fine acicular; usually implanted by one extremity of the prism. Prismatic faces i commonly striated horizontally, and thus distinguishable, in distorted crystals, from the pyramidal. Crys- tals often grouped by juxtaposition, not proper twins. Frequently in radi- ated masses with a surface of pyramids, or in druses having a sui-face of pyramids or short crystals. Twins : twinning-plane, (1), the basal ])lane O (f. 500) ; very generally penetration-twins, as illustrated in f. 205, p. 89. (2) The pyramid 1-2, truncating the ed.o-e between +It and —R, divergence of axes 84° 33'. Other methods of twinning rare, parallel to i, to B, to 495 499 V 496 497 A 500 501 (7\ f#^ ^•J X i i <^ ^^ y 498 R 502 ^R, etc. (Jenzsch). Also in pseudo-trillings on calcite, with 2-2 as th^ approximate twinning-plane (see f. 330, p. 101). Massive; coarse or fi^ne granular to flint-like or crypto-crystalline Sometimes mammillary, stalactitic, and in concretionary forms. 504 505 506 n.=7. G.=2'5-2'8 ; 2-G413-2-6541 (Beudant). Lustre vitreous, some times inclining to resinous ; splendent — nearly dull. Colorless when pure : often various shades of yellow, red, brown, green, blue, black. Streak while, of pure varieties; if impure, often the same as the (tolor, but much paler. Transparent — opaque. Fracture perfect conchoidal — subccmchoi- dal. Tough — brittle — friable. Folarizatiou circular, see pp. 142-144. 286 DESCRIPTIVE MINERALOGY Comp — Pure Rilica, or Si02=0xygen ."JS'SS, silicon 4667=100. In massive varieties oh«ii mixed with a little opal-silica. Impure varieties contain iron sesquioxide, calcium carbonate, clay, sand, and various minerals. Var. — I Crystallized (phenocrystalline), vitreous in lustre. 2. Flint-like, massive, or cryp- tocrystalline. The first division includes all ordinary vitreous quartz, whether having crya- tallme faces or not. The varieties under the second are in general acted upon somewhat more by attrition, and by chemical agents, as tluohydric acid, than those of the first. In all kinds made up cf layers, as agate, successive layers are unequally eroded. A. PriENOCKYSTALLINE OR VlTHEOUS VaKIETIES. /■ 1. Ordinary Oi-yKtaiUzed ; Rock CrytsUil. Cv^loi/ess quartz, or nearly so. whether in dis- tinct crystals or not. / 2. Asteriated ; IStar quartz (Stemquartz, Germ.). Containing within the crystal whitish ^ or colored radiations along the diametral planes. ^ 3. Amethystine ; Amethyst. Clear purple, or bluish-violet. The color is supposed to be due to manganese. ^ 4. Rose. Rose-red or pink, but becoming paler on exposure. Common massive, and then usually much cracked. Lustre sometimes a little greasy. Fuchs states that the color is due to titanic oxide. It may come in part from manganese. \y 5. Yellow ; False Topaz. Yellow and pellucid, or nearly so ; resembling somewhat yellow topaz, but very different in crystallization and in absence of cleavage. ^ 6. Smoky. Cairngorm Stone. Smoky -yellow to smoky-brown, and often transparent ; but varying to biownish-black, and then nearly opaque in thick crystals. The color is due to organic compounds, according to Forster. \J 7. AfUky. Milk-white and nearly opaque. Lustre often greasy, and then called Greasy quartz. y^ 8. Gat^s Eye {Ksitzenauge, Germ.). Exhibiting opalescence, but without prismatic colors, an effect due to fibres of asbestus. V 9. Aventurine. Spangled with scales of mica or other mineral. 10. Impure from the presence of distinct minerals distributed densely through the mass. ^ The more common kinds are those in which the impurities are : {a) fe)'r%iginous, either red or yellow iron oxide ; (b) c?>loritic, some kind of chlorite ; (c) actinolitic ; (d) micaceo-u.s ; {e) are- naceous, or sand. Quartz crystals also occur penetrated by various minerals, as topaz, corun- dum, chrysoberyl, garnet, different species of the hornblende and pyroxene groups, rutile, hematite, gothite, etc., etc. ^ Containing liquids in cavities. These liquids are seen to move with the change of position of the crystal, provided an air-bubble be present in the cavity. The liquid is either watej (pure, or a mineral solution), carbon dioxide, or some petroleum-like or other compound. B. CrYPTOCRYSTALLINE VARIETIE8. / 1. Chalcedony. Having the lustre nearly of wax, and either transparent or translucenu Color white, grayish, pale-brown to dark-bro^vn, black ; tendon-color common ; sometimes deli- cate blue. Also of other shades, and then having other names. Often mammillary, botryoi- dal, stalactitic, and occurring lining or filling cavities in rocks. It is true quartz, with some disseminated opal. ^ 2. Carnelian. A clear red chalcedony, pale to deep in shade ; also brownish-red to })rown, the latter kind reddish-brown by transmitted light, o. Chrysoprase. An apple-green chalcedony, the oilor due to the presence of nickel ^^oxide. 4. Prase. Translucent and dull leek-green ; so named from -//l/ct'U', n leek. Always regarded ^ as a stone of little value. The name is also given to crystalline quartz of the same color. ^ 5. Plasma. Rather bright-green to leek-gi-een. and also sometimes nearly emerald -green, and gubtranslucent or feebly translucent ; sometimes dotted with white. IIeU>tr»pe, or Bkod-itone, is the same stone essentially, with small spots of red jasp<-r, looking like drops of bloo-l. 6. Agate. A variegated chalcedony. The colors are either banded or in clouds, or due to visible impurities, a. Banded. The bands are delicate parallel lines, of white, t«ndon-like, wax-like, pale and dark-brown, and black colors, and sometimes blui.sh and other shades. They follow waving or zigzag courses, and are occasionally concentric circular, as in ihe eye- dgate. The bands are the edges of layers of deposition, the agate having been formed by a deposit of silica from solutions intermittently supplied, in irregular cavities in rocks, aud OAXGEN COMPOUNDS — SILICA. 287 deriving their concentric waving courses from the irregularities of the walls of the cavity Owing also to the unequal porosity, agates may be varied in color by artificial means, ft. Ir regularly clouded. The colors various, as in banded agate, y. GoLora due to visible impurities, including Moss-agate, filled with brown moss-like or dendritic forms distributed through the mass ; JJendritic Agate, containing brown or black dendritic markings. There is also Agatized Wood : wood petrified with clouded agate. \^ 7. Onyx. Like agate in consisting of layers of different colors, but the layers are in even planes, and the banding therefore straight, and hence its use for cameos, the head being cut in one color, and another serving for the background. The colors of the best are perfectly well defined, and either white and black, or wUite, brown and black alternate. "/^ 8. Sardonyx. Like onyx in structure, but includes layers of carnelian (sard) along with others of white or whitish, and brown, and sometimes black colors. t^ 9. Jaspr. Impure opaque colored quartz, {a) lied iron sesquioxide being the coloring matter, (b) Brownish, or ochre-yellow, colored by hydrous iron sesquioxide, and becoming red when so heated as to drive off the water, (c) Dark-green and brownish-green, (d) Grayish- blue, (e) Blackish or brownish-black. (/) Striped or riband jasper (Baudjaspis, Germ.), having the colors in broad stripes, (g) Egyptian jasper, in nodules which are zoned in brown and yellowish colors. Porcelain jasper is nothing but baked clay, and differs from true jasper m being B. B. fusible on the edges, lied porphyry, or its base, resembles jasper, but is also fusible on the edges, being usually an impure feldspar. V/' 10. Agate-Jasper. An agate consisting of jasper with veinings and cloudings of chalcedony. ^ 11. Siliceous sinter. Irregularly cellular quartz, formed by deposition from waters contain- ing silica or soluble silicates in solution. \^ 12. Flint (Feuerstein, Oerrn.). Somewhat allied to chalcedony, but more opaque, and of dull colors, usually gray, smoky-brown, and brownish-black. The exterior is often whitish, from mixture with lime or chalk, in which it is imbedded. Lustre barely ghstening, sub- vitreous. Breaks with a deeply conchoidal fracture, and a sharp cutting edge. The flint of the chalk formation consists largely of the remains of infusoria (Diatomsi, sponges, and other marine productions. The coloring matter of the common kinds is mostly carbonaceous matter. 13. Hornstone (Hornstein, Germ.). Resembles flint, but more brittle, the fracture more splintery. Ghert is a term often applied to hornstone, and to any impure flinty rock, includ- ing the jaspers. 14. Basanite, Lydinn Stone or Touchstone. A velvet-black siliceous stone or flinty jasper, used on account of its hardness ami black color for trying the purity of the precious metals. The color left on the stone after rubbing the metal across it indicates to the experienced eye the amount of alloy. It is not splintery like hornstone. Pyr., etc. — B.B. unaltered; with borax dissolves slowly to a clear glass; with soda dis- solves with effervescence ; unacted upon by salt of phosphorus. Insoluble in hydrochloric acid, and only slightly acted upon by solutions of fixed caustic alkalies. When fused and cooled it becomes opal-silica, having G. =2"3. Diff. — Quartz is distinguished by its hardness — scratching glass with facility ; infusibilit^ — not fusing before the blowpipe ; insolubility — not attacked by water or the acids ; uncleava- bility — one variety being tabular, but proper cleavage never being distinctly observed. To these ubaracteristics the action of soda B. B. may be added. Obi. — Quartz occurs as one of the essential constituents of granite, syenite, gneiss, mica schist, and many related rocks ; as the principal constituent of quartz-rock and many sand- stones ; as an unessential ingredient in some trachyte, porphyry, etc. ; as the vein-stone in various rocks, and for a large part of mineral veins ; as a foreign mineral in the cavities of trap, basalt, and related rocks, some limestones, etc. , making geodes of cry.stals, or of chalcedony, agate, carnelian, etc. ; as imbedded nodules or masses in various limestones, constituting the flint of the chalk formation, the hornstone of other limestones — these nodules .sometimes becoming continuous layers ; as masses of jasper occasionally in limestone. It is the principal material of the pebbles of gravel beds, and of the .sands of the sea-shore and sand beds every- where. Silica also occurs in solution (but mostly as a soluble alkaline .silicute) i" hp.ated n=itural waters, as those of the Geysers of Iceland, New Zealand, and California, and the Yellowstone Park, and very sparingly in many cold mineral waters. Switzerland, Dauphiny, Piedmont. tLe Carrara quarries, and numerous other foreign locali- ti(!S, afford fine specimens of rock crystal. Amethj'sts are brought from India, Ceylon, and Persia, also Transylvania. The amygdaloids of Iceland and the Faroe Islands, afford magni- ficent specimens of chcdceduny ; also Iliittenberg and Loben m Carinthia. etc. The fiinest carnelians and agates are found in Arabia, India. Brazil, Surinam, Oberstein, and Saxony. Cats eye, in Ceylon, the coast of Malauar, and also in the Harz and Bavaiia. Heliotrope., il Bucharia, Ta tary, Siberia. 288 DESCKIPTIVE IVUNERALOGY. In New York, quartz crystals are abundant in Herkimer Co. Fine dodecahedral ciystala, at the beds of specular iron in St. Lawrence Co. In Antwerp, Jefferson Co., at Diamood Island and Diamond Point, Lake Georg:e, Pelham and Chesterfield, Mass. , Paris and PeiTy, Me., Bentoii, N. H., Sharon, Vt., Meadow Mount, Md., and Hot Springs, Ark., are other localities ol' quartz crj'stal. For other localities, see the catalogue of localities in the latter part of this volume. liouc (jiiiiriz, at Albany and Paris, Me., Acworth, N. H., and elsewhere ; smuki/ quartz^ at Goshen. Mass., Richmond Co., N. Y., Pike's Peak, Colorado, etc. ; amethyst, at Keweenaw Point and Thunder Bay. etc.. Lake Superior; also at Bristol, Rhode Island, near Greensboro, N. C. ; Specimen Mountain, Yellowstone Park. Crystallized green quartz, at Providence, Delaware Co., Penn ; at EUeuville, N. Y. Chalcedony and agates about Lake Superior, the Llississippi, and the streams to the west, etc. Red jasper is found in pebbles on the banks of the Hudaon at Troy ; red and yellow, near Murj^hy's, Calaveras Co. , Cal. Heliotrope occupies veins in slate at Bloomingrove. Orange Co., N. Y. Several varieties of this species have long been employed in jewelry. The amethy.ft has always been esteemed for its beauty. Cameos are in general made of onyx, which is well fitted for this kind of miniature sculpture. Jasper admits of a brilliant polish, and is often formed into vases, boxes, knii'e-handles, etc. It is also extensively used in the manufacture of Florentine mosaics. The caruelian is often rich in color, but is too common to be much esteemed ; when first obtained from the rock they are usually gray or grayish-red ; they receive their fine colors from an exposure of several weeks to the sun's rays, and a subsequent heating in earthen pots. The colors of agate, when indistinct, may be brought out by boil- ing in oil, and afterward in sulphuric acid ; the latter carbonizes the oil absorbed by the porous layers, and thus increases the contrast of the different colors. a^ ^< TRIDYMITE* 507 Hexkgonal. 1 A 1 = 124° 3' (basal) ; 1 A 1 = 127° 35' (terminal) ; h — 1-6304 (v. E.ath). Cleavage O, imperfect. Crys- tals minute, commonly tabular (f. 507), formed by the prism and basal ])lane ; also fi-equently in twins and trillings with (1) -|-, and (2) f as the twinning-planes. Double refraction positive, IT. = 7. G.=2-282-2-326. Lustre vitreous, on the face pearly. Colorless, becoming white on weathering. Fracture coii- choidal. Comp. — Pure silica, or SiOj, like quartz. Pyr. — B.B. infusible. Fuses in .soda with effervescence, forming a colorless glass. Soluble in a boiling saturated solution of sodium carbonate. Obs. — First found in cavities in the trachyte from Cerro St. Cristoval. near Pachucn, Mexico. Also in the trachyte of the Siebengebirge, and in related rocks from mjuiy looalitien. Forming on one occasion the mass of white volcanic ashes, from the island Vulc.xno. Also in microscopic crystals inclosed in opal, and in quartz. ASMANITE (3faxkelyne). — A third form of silica, crystallizing in the orthorhombic system, *'isomorphou8 with brookite." H. =55. G. =2-345. Found in very minute crystallino graius, generally rounded, in the meteoric iron of Breitenbach. OPAL. Massive, amorphous ; sometimes small reniform stalactitic, or large tuberose. Also earthy. H.=5-5-6"5. G.=l'9-2-3. Lustre vitreous, frequently subvitreous : often inclining to resinous, and sometimes to pearly. Color white, yellow, OXYGEN COMPOUNDS SILICA. TASU red, brown, green, gray, generally pale ; dark colors arise ivom foreigu admixtures ; sometimes a j-ich play of colors, or different colors by refra(;ted and retiected light. Streak white. Transparent to nearly opaque. Comp. — Silica. SiOj, as for quartz, the opal condition being one of lower degrees of liard- ness and specific gravity. Water is usually present, but it is regarded as unessentiaL It varies in amount from 2 to 21 p. c. ; or, raosdy, from 3-9 p. c. V Var. — 1. Precious Opal. Exhibits a play of delicate colors, or, as Pliny says, presents various refulgent tints in succession, reflecting now one hue and now another. Seldom larger than a hazel-nut. Donbly refracting (biaxialj, Behre/is. 3. Fire-opal. Hyacinth-red to honey -yellow colors, with fire-like reflections somewhat irised on turning. 3. Gira.sol. Bluish-white, translucent, with reddish reflections in a bright light. 4. Goinmoiv Opal. In part translucent ; (a) milk-white to greenish, yellowish, bluish; {b) Resin-opal (Wachsopal, Pechopal, Ger/ti.), wax-, honey- to ochre-yellow, with a resinoua lustre; (cj dull "olive-green and mouutain-green ; [cl) brick-red. 5. Cacholonfj. Opaque, bluish-white, porcelain-white, pale-yellowish or reddish ; often adheres to the tongue, and contains a little alumina. 6. Opal-agate. Agate-like in structure, but consisting of opal of different shades of color. 7. Jas]>opal. Opal containing some yellow iron sesquioxide and other impurities, and hav- ing the color of yellow jasper, with the lustre of common opal. 8. Wood-opal {'Kolzo-psl, Oerm.). Wood petrified by opal. 9. Hyalite. Clear as glass and colorless, coustitutmg globular concretions, and also crusts with a globular, reniform, botryoidal, or stalactitic surface ; also passing into translucent, and whitish. 10. Fiorite, Siliceous Sinter. Includes translucent to opaque, grayish, whitish, or brownish Incrustations, porous to firm in texture ; sometimes fibrous-like or filamentous, and, when so pearly in lustre, formed from the decomposition of the siliceous minerals of volcanic rocka about fumaroles, or from the siliceous waters of hot springs. It graduates at times into hyalite. Oeyserite constitutes concretionary deposits about the Iceland and Yellowstone {pealite) geysers, presenting white or grayish, porous, stalactitic, filamentous, cauliflower- like forms; also compact-massive, and scaly-massive; H.=o; rarely transparent, usually opaque ; sometimes falling to powder on drying in the air. 11. Float-stone. In light concretionary or tuberose masses, white or grayish, sometimes cavernous, rough in fracture. So light, owing to its spongy texture, as to float on water. The concretions sometimes have a fliut-iike nucleus. 12. Tripoiite. Formed from the siliceous shells of Diatoms and other microscopic species, as first made known by Ehrenberg, and occurring in deposits, often many miles in area, either uncompacted, or moderately hard. lafusoi ial Earth, or Earthy Tnpolite, a very fine-grained earth looking often like an eartny chalk, or a clay, but harsh to the feel, and scratching glass when rubbed on it. Pyr., etc — Yields water. B.B. infusible, but becomes opaque. Some yellow varieties, oontaining iron, turn red. Oba. — Occurs filling cavities and fissures or seams in igneous rocks, porphyry, and some metallic veins. Also imbedded, like flint, in limestone, and sometimes, like other quartz concretions, in argillaceous beds ; also formed from the siliceous waters of some hot springs • also resulting from the mere acoumulation, or accumulation and partial solution and solidifi- cation, of the siliceous shells of infusoria — which consist essentially of opal-silica. Precious opal occurs in Hungary; in Honduras ; and iVIexico. Fire opal occurs at Zimapau in Mexico ; Faroe ; near San Antonio, Honduras. Common opal is abundant at Telkebanya in Hungary; in Moravia; in Bohemia ; Stenzelberg in the Siebengebirge ; Faroe, Iceland; the Giant's Causeway, at many localities. In U. S., hyaAte occurs sparingly in n! York at the Phillips ore bed, Putnam Co. ; in Georgia, in Burke and Scriven Cos. ; in Washington Co. good fire opal. At the Geysers on the Fire Hole river, Yellowstone Park, geyserite is abundant! The precious opal, when large, and exhibiting its peculiar play of colors in perfection, is a gem of high value. It is cut with a convex surface. Melanopuloqite (LfM^iitej.— Occurs in minute, colorless, cubes coating sulphur orystali from Qirgenti, Sicily. Contains SiOi 8(3-3 p. c, SO3 7 2, H^O 2 9 ; chemical nature doubt- ful. Turns black upon ignition, hence the name. 19 ^•;\ 293 DESCRIPTIVE MINERALOQY. IL TERNAEY OXYGEN COMPOirNDS. 1.. SILICATES.— A. ANHYT»FtOUS S£LICATES. a. BisiLicATES. General Formula ESiOo cleavage-surfaces to vitreous brouzite (a) Amjpldhole Groujp. Pyroxene Section, \/ ENSTATITE. Bronzite. Protobestdte. Orthorhombic. 7a/=8S°_16' and 91° 44' (Breitenbach meteorite, t>. Lang)\c :b'.d = 0-58853 : 1-03086 : 1. Cleavage: Tj easy ; i-i, i-l, less so. Sometimes a fibrous appearance on the cleavage-sni'face. Also massive and lamellar. H. = 5'5, G.=:3-l-3-3. Lustre a little pearly on often metalloidal in the variety. Color grayish-white, yellowish-white, greenish-white, to olive-green and brown. Streak uii- colored, grayish. Double refraction positive ; optic- axial plane brachydiagonal ; axes very divergent. Comp., Var. — MgSiOa = Silica GO, magnesia 40 =r 1 00 ; also (Mg, Fe) SiOs. Var. 1. With little or no iron; Enstatite. Color white, yellowish, grayish, or greenish- white ; lustre pearly-vitreous; G. =3-10-313. V/dadnite, which makes up 90 p. c. of the Bishopville meteorite, belongs here and is the purest kind ; Victorite {Meunier), from the Deesa (Chili) meteoric iron is probably identical. 2. Ferriferous ; Bronzite. Color grayish -green to olive-green and brown; lustre of cleav- age-surface adamantine pearly to submetallic or bronze-like. The ratio of Mg : Fe varien from 11 : 1 to 8 : 1. Analysis of bronzite from Leiperville by Pisani, SiOa 57-08, itlOs 0"38, FeO 5-77, MgO 35-59, H.,0 •90=99-62. Pyr., etc. — B.B. almost infusible, being only slightly rounded on the thin edges ; F.=6. Insoluble in hydrochloric acid. Diff. — Distinguished by its infusibility from varieties of amphibole, which it resembles. Obs. — Occurs near Aloysthal in Moravia ; in the Vosgcs ; at Kupf erberg in Bavaria ; at Baste in the Ka.vzXFroiobdstite); in the chrj solite bombs in the Eifel ; in immense crystals with apatite, near Bamle, Norway. In Pennsylvania, at Leiperville and Texas ; at Brewster, N. Y. Bronzite is quite common in meteorites. DesCloizeaux first defined the limits of this species, as here laid down. Named from '(ycrdrris, an ojiponent, because so refractory. The name bron^itehas priority, but a bronze lustre is not essential, and is far from universal. 508 r^ ^Jtx I 11 I i Bamle, Norway, -y Orthorhombic. I A 1=91° 32^, r. Rath {amblystegite). Cleava v for hypersthene. Di.\CLA8lTE. — Near bronzite ; diilers in optical characters. (Mg,Fe,Ca)Si03. Harzburg; Ouadorrama, Spain. / l/ WOLLASTONITE. Tabular Spar. Tafelspath, Germ. Monoclinic. 0= 69° 48', /a 7 = 87° 28', 0A2-i = 137° 48' ; c:b:d = 0-4338 : 0*89789 : 1. Fig. 510 in the pyroxene or normal position, but wi""^"" the edge 0/i-i the obtuse edge ; f. 511 in the position given the crys- tals fj\ authors who make i-i the plane O, and 2-i the plane 7. O A — 1-i = 160^ 30', O A 1-i = 154" 25', i-i A - 2 = 132° 54', i-i A 2 = 93° 52'. Rarely in distinct tabular crystals. Cleavage: O most distinct; i-i less so; 1-i and — 1-^' in traces. Twins: twinning-plane i-i. Usually cleav- able massive, with the surface appearing long librous,, fibres parallel or reticulated, rather strongly coherent. 610 511 H.=4-5-5. G. = 2-78-2"9. Lustre vitreons, inclining to pearly upon the faces of perfect cleavage. Color white, inclining to gray, yellow, red, or brown. Streak white. Subtraiisparent — translucent. Fracture uneven, sometimes -^ery tough. Optic-axial plane i-i ; divergence 70^ 40' for the red rays ; bisectrix of the acute angle negative ; inclined to a normal to i-i 57° 48', and to a normal to O 12°, DesCl. 292 DESCRIPTIVE MIXERALOGT. Comp.~CaSi03 = Silica 51-7, lime 48-3=100. Pyr., etc. — In the matrass no change. B.B. fuses easily on the edges; ■wdth some soda, a blobby glass, with more, swells up and is infusible. With hydrochloric acid gelatinizes; most vnrieties effervesce slightly from the presence of calcite. Di£f. — Dififers from asbestos, and tremoUte in forming a jelly with acids, as also by its more ritreous fracture ; fuses less readily than natrolite and scolecite ; when pure does not etfer- vssce with acids like the carbonates. Obs. — Wollastonite is found in regions of granite and granular limestone ; also in basalt and lavas. Occurs in Hungary; in Finland; and in Norway; at Gockum in Sweden ; in the Harz ; at Auerbach, in granular limestone ; at Vesuvius. In the U. S. , in N. York, at Wills- borough ; at Lewis ; Diana, Lewis Co. In Penn., Bucks Co. At the Cliflf Mine, Keweenaw Point, Lake Superior. In Canada, at Grenville. v/ PYROXENE. Monoclinic. C = 73° 59', IaJ= 87° 5', 6> A 2-i = 131° 17' ; G:b:d = 0-5412 : 0-91346 : 1. OaI= 100° 57', Oa- 1-i = 155° 51', OAl-i = 148° 35', 6>A -1 = 146° 9', 6>Al = 137° 49', -1 A -1 = 131° 24'. Cleavage : J rather perfect, often interrupted ; i-i sometimes nearly per- 513 r " I 515 513 519 feet; i-l imperfect; O sometimes easy. Crystals nsnally thick and stout. Twins: twinning-plane ^-^ (f. 521). Often coarse lamellar, in large masses, parallel to O or i-i. Also granular, particles coarse or line ; and fibrons, fibres often fine and long. H.=5-6. a. = 3-23-3-5. Lnstre vitreous, inclining to resinous ; some pearly. Color green of various shades, verging on one side to white or grayish- white, and on the other to brown and black. St]'eak white to gray and gi-ayish-green. Transparent — opaque. Fracture conchoidal — nneven. Brittle. In crystals from Fassa, optic-axial plane i4; divergence 110° to 113°; bisec- trix of the acute augle positive, inclined 51° 6' to a normal to i-i and 22° 55' to a normal to O, DesCl. OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 293 Comp., Var. — A biBilicate, having the general formula RSiOa, where E may be Ca,Mg, Fe,Mn, sometimes also Zn,Ka2,Na2. Usually two or more of these bases are present. Th« first three are most common ; but calci im is the only one that is present always and in large percentage. Besides the substitutions of the above bases for one another, these same basea are at times replaced by 2tl,Fe,Mn, though sparingly, and the silicon occasionally by alumi- num. The varieties proceeding from these isomorphous substitutions are many and diverse ; and there are still others depending on the state of crystallization. The foliated and fibroua kinds early received separate names, and for a while were regarded as distinct species. Fibroua or columnar forms are very much less common than in hornblende, and lamellar or foliated kinds more common. The crystals are rarely long and slender, or bladed, like those of that species. The most prominent division of the species is into (A) the non-aluminous ; (B) the alumi- nous. But the former of these groups shades imperceptibly into the latter. These two groups are generally subdivided according to the prevalence of the different protoxide elements. Yet here, also, the gradation from one series to another is in general by almost insensible shades as to composition and chemical characters, as well as all physical qualities. I. Containing little or no Alumina. ^\, Lime-Magnesia Pyroxene ; Malacolite. Diopside, Alalite, White Coccolite. Color white, yellowish, grayish -white to pale green. In crystals : cleavable and granular massive. Sometimes transparent and colorless. G.=83-3o8. Formula, CaMgSi206 = SLlica 55 '6, mag- nesia 18 o, lime i!5-9. Sometimes Ga : Mg=l : 2 ; less than 4 p. c. of iron are present. v/- 2. Lime- Magnesia- Iron Pyroxene ; Saiilite. Color grayish-green to deep green and black ; sometimes grayish and yellowish-white. In crystals ; also cleavable and granular massive G.=3'25-3-4. Named from Sala in Sweden, one of its localities, where the mineral occurs in masses of a grayish-green color, having a perfect cleavage parallel to the basal plane (0). Formula (Ca,Mg,Fe)Si03. The ratio of Ca : Mg : Fe varies much, =3 : 3 : 1, 2 : 3 : l,etc. The ratio=4 : 3 : 1, corresponds to silica 53 7, magnesia 13 4. lime 24-9, iron protoxide 8 0=100. Sf DiALLAGE. Part of the so-called diulUiye, or thin foliated pyroxene, belongs here, and the rest under the corresponding division of the aluminous pyroxenes. Color grayish-green to bright grass-green, and deep green; lustre of cleavage surface pearly, sometimes metalloidal or brassy. H.=4. G. =3'2-3oO, Composition near the preceding ; analysis by vom Rath, Neurode, SiOj 53 GO, AIO3 1 -99, FeO 8-95, MnO 0-28, MgO 13-08, CaO 21-Ot;, H.O 0-8lJ=99-82. With this variety belongs part also of what has been called hypersthene and bromite — the part that i« easily fusible. Common especially in serpentine rocks. Named from i^uiA/Myij^ dif- ference, in allusion to the dissimilar cleavages. c/ 3. Lron-Liine Pyroxene. Hedenbeugite. Color black. In crystals, and also lamellar massive ; cleavage easy parallel to i-i. G. =3 '5-3 -58. Formula CaFeSi.,06 (Mg being absent) = Silica 48 39, lime 2218, iron protoxide 29-43 = 100. Asteroite is a similar pyroxene con- taining also Mn (Igelstrom), Sweden. yf 4. Lime-Lron-Majigane.se- Zinc Py>'oxene ; J EFFERSONiTE. Color greenish-black. Crystals often very large (3-4 in. thick), with the angles generally rounded, and the faces uneven, as if corroded. G.=3-3G. Analysis, Franklin, N. J., by Pisani, SiO. 45-95, zilOa 0-85, FeO 8-91, MnO 10-20, ZuO 1015, CaO 21-55, MgO 3-Gl, ign 0-35=101-57. II. Aluminous. Alumiiunis Lime- Magnesia Pyroxene; Leucaugite {Dana). Color white or grayish. Analysis, Bathurst, C, by Hunt, SiO, 51-50, AIO3 G-15, FeOa 035, MgO 17G9, CaO 23-80 HoO 1-10 = 100-59. Looks like diopside. H. =0-5. G.=3-19. Hunt. Named from Aev/cor, white. Aluminous Idme-Magnesia-Lron Pyroxene; Fassaite, Augite. Color clear deep-green to Gfreenish-black and black ; in crystals, and also massive ; subtranslucent to opaque. G. =3 25-3 -5. Contains iron, with calcium and magnesium, also aluminum. Analysis of augite from Montreal by Hunt, SiOj 49-40, AIO3 G-70, l^eOa 783, MgO 13-00, CaO 21 88, Na.O 074, H2O 0-50=100-11. a. Fassaite (or Pyrgom). Includes the green kinds found in metamorphic rocks. Named from the locality at Fassa in Piedmont, which affords deep-green crystals, sometimes pistachio- green, like the epidote of the locality. b. Augite. Includes the greenish or brownish-black and black kinds, occurring mostly in eruptive rocks, but also in metamorphic. Named from aiy//, lustre. 294 DESCRnTITE MrNERALOGT, Pyr., etc. — Varying widely, owing to the wide variations in composition in the difiFercnt varieties, and often by insensible gradations. Fusibility, from the almost infusible diallapre to 3'75 in diopside ; ij '5 in sahlite ; 3 in jeffersonite and augite ; 2'5 in hedenbergite. Va- rieties rich in iron afford a magnetic globule when fused on charcoal, and in general theii fusibility varies with the amount of iron. Jeffersonite gives with soda on charcoal a reaction for zinc and manganese ; many others also give with the fluxes reactions for manganese. Most varieties are unacted upon by acids. Diflf.— See Amphibole, p. 297. Obs. — Pyroxene is a common mineral in crystalline Limestone and dolomite, in serpentine, and in volcanic rocks ; and occurs also, but less abundantly, in connection with granitic rocka and metamorphic schists. The pyroxene of limestone is mostly the white and light-green or gray varieties ; that of most other metamorphic rock, sometimes white or colorless, but usually green of different shades, from pale green to greenish- black, and occasionally black; that of serpentine is sometimes in fine crystals, but often of the foliated green kind called diallage ; that of eruptive rocks is the black to greenish-black aiigite. Prominent foreign localities are : malacoUte {diopHide], Traversella, Ala in Piedmont; Sala, Tunaberg. Sweden ; Pargas ; Achmatovsk ; etc. 8ahlile^ Sala ; Arendal ; Degeroe ; Schwarzen- berg ; etc. Hedenbergite, Tanaherg; Arendal Augile, Yassiithal; Vesuvius; etc. — inmost dolerytio igneous rocks. In N. America common (see list of localities at the close of the volume). Some localities are: In Mass., at the Bolton quarries. In Conn., at Canaan. In N. York, at Warwick. Mon- roe, Edenville, Diana. In iV". Jersey, in Franklin. In I'enn., near Attleboro'. In Canada, at Bytown, at Calumet I. , at GrenviUe. / ACMITE. — Monoclinic. In slender pointed crystals (hence name) in quartz. H. =6. G. = 3'2-8'53. Color brownish to reddish-brown, in the fracture blackish-green. Opaque. Frac- ture uneven. Brittle. liSi03,R=Nao,Fe, or Fe(Fe=3R); analysis by llammelsberg. SiOj 51-66, FeOs 2828, FeO 523, MnO 069, Na,0 12 46, K.O 043, TiO 111, ign 39= 100-25 Kongsberg, Norway. .^QIRITE. — Near pyroxene in form, but contains alkalies. H. =5-5-0. 6. =3-45-3-58. Color greenish-black. Subtranslucent to opaque. Analysis Ramm., Brevig, SiO) 50-25, AlOj 1-22, Fe03 22-07, FeO 8-80, ]MnO 1-40, CaO 5-47, MgO 1-28, Na.O 9 29, K,0 94=100-72. Also from Magnet Cove, Arkansas. \r RHODONITE. Triclinie, but approximately isoinorplious vvitli pyroxene. Cleavage: 1 perfect; 6^ less perfect. Usually massive. 532 H.=5-5-6-5. G.=3-4-3'08. Lustre vitreous. Color light hrowuish-i-ed, tiesli-i-ed, sometimes greenish or yellowish, when impuj-e ; often black outside from ex- posure. Streak white. Transparent — opaque. Frac- ture conchoidal — uneven. Very tough when massive. Comp., Var MnSi03 = Silica 45-9, manganese protoxide 54-1 = 100. Usually some Fe and Ca, and occasionally Zn replace part of the Mn. Ordinni-y. (a) Crystallized. Either in crystals or foliated. The ore in crystals from Paisberg, Sweden, was named I'aisbergite under the idea that it was a distinct species. {b) Granular massive. Cnlciferoris ; BusT-VMITE. Contains Si/to 15 p. c. of lime replacing part of the manganese. Often also impure from the presence of cal- cium carbonate, which suggests that part of the lime replacing the manganese may have come from partial alteration. Grayish-red. Zinciferoahy Fowlkiute. In crystals and foliated, ^^ the latter looking much like cleavable red feldspar ; the crystals sometimes half an inch to an inch through. / \ 7=86' 30', Torrey. G. =3 -44, Thomson. Pyr., etc. — B.B. blackens and fuses mth slight intumescence at 2-5 ; with the fluxes givea reactions for manganese ; fowlerite gives witli soda on charcoal a reaction i'or zinc. Slightly acted upon by acids. The calciferous varieties often effervesce from nn chanical admix- ture with calcium carbonate. In powder, partly dissolves in hydrochloric acd, and the in soluble part becomes of a white color. Darkens ou exposure to the air, and sometimea bf'comes nearly black. Obs. — Occurs at Longban, near Philip.stadt in Sweden ; also in the Harz ; in the district of OXTGEN COMPOUNDS — ANHYDROUS SILICATES. 295 ITatherinenberg in the Ural ; in Cornwall, etc. Occurs in Warwick, Mass. ; Blue Hill Bay, Maine ; near Hinsdale, N. H. ; fowlerite {keatingine) at Hamburg and Sterling, New Jersey. Named from p6ioi\ a rose, in allusion to the color. B.viuxGTONiTE.— Triclinic. ORSiOa + FeSisOg. with R=Fe(Mn) : Ca(Mg)-2 : 3 (Ramm.). Analysis, Rammelsberg, SiO> 51-23, FeOa U-OO, FeO 10-26, MnO 7-91, MgO 0-77, CaO 19'82, ign=0--44=lC0-92. Color greenish-black. Arendal; Nassau; Devonshire; Baveno. SPODUMENE.* Monoclinic. C= GO'' 40' /a/=87°, 6> A 24 = 130' large. Cleavage: i-i verv perfect; / also perfect; 14 ill traces ; in striae on ^4. Twins : twinning- plane i-i. Also massive, with bi-oad cleavage surface. H. = 6-5-7. G.=: 3- 13-3-10. Lustre pearly. Cross fracture vitreous. Color grayisii-green, passing into greenish-white and grayish-white, rarely faint-reddish. Streak uncolored. Translucent — subtranslucent. Frac- ture uneven. 1/ 30'. Crystala Comp.— 3RSi03-f4AlSi309 ; R^Lij mostly. Silica 64 2, alu- mina 29-4. Iithia6-4=100. Sometimes Li : Na(K) = 20 : 1, Ramm. Pyr., etc. — B. B. becomes white and opaque, swells up, imparts a purple red color (hthia) to the flame, and fuses at 3 5 to a clear or white glass. The powdered mineral, fused with a mixture of potassium bisulphate and fluor on platinum wire, gives a more in- tense lithia reaction. Not acted upon by acids. Dlff. — Distinguished by its perfect orthodiagonal as well as piismatic, cleavage ; has a higher specific gravity and more pearly Norwich, Mass. lustre than feldspar or scapolite. Gives a red flame B B. Obi. — Occurs on the islajid of Ut j, Sweden ; near Sterzing and Lisens in the Tyrol; at Killiuey Bay, near Dublin, and at Peterhead in Scotland. At Goshen, Mass. ; also at Chesterfield and Norwich, M:iss. ; at Windham, Maine ; at Winchester, N. H.; at Brookfield, Ct. Petalite.— 3Li.2Si,05+4A]SioOi5 = Silica 77-97, alumina 17-79, lithia 3-57, soda 067= 100. Ramm. Q. ratio Li : i^l : Si=l : 4 : 20, or for bases to silicon=l : 4. H.:=6-6'5. Qt, ^2-5. Colorless; white. Utd, Swedeu, 'EVoo, [castoi'itc) \ Bolton, Mass. V ATTiph ihole Section. ANTHOPHYLLITE. Orthorhombic. I\I= 125° to 125^ 25'. Cleavage: i-l perfect, / leaa so, i-i difficult. Commonly lamellar, or fibrous massive ; fibres often very ^leiider. H.=5*5. G. = 3-l-3-2, Lustre somewhat pearly upon a cleavage sur- face. Color brownish-gray, yellowish-browii, brownish-greon, sometimes Bubmetallic. Streak uncolored or grayish. Translucent to subtranslucent. Biittlc. Double refraction positive; opti'-al axes in the brachydiagonaJ section. \ 29G DESCKIPriVE MNERALOGT. Comp — (Fe,Mg)Si03, Fe : Mg=l : 3=Silica 55 5, magnesia 27-8, iron protoxide 16-7=^ 100. Pjn^., etc. — B. B. fuses with great difficulty to a black magnetic enamel; with the iluxea gives reactions for iron ; unacted upon by acids. Obs. — Occurs near Kongsberg in Norwa)', and near Modum. Also at Hermannschlag, Moravia. Anthophyllite loears the same relation to the Amphibole Group that enstatite and hyper- sthene do to the Pyroxene Group. KuPFFKHiTii. — Probably MgSiOa, with a little Fe. 7 A 7=124' 30', hence an emtatite-horn- blende. Color emerald-green (chrome). Tunkinsk Mts. , Miask. Analysis of a similar min- eral from Perth, Canada, Thomson, SiO, 57-60, AlOs 8-20, FeO 210, MgO 29-30, CaO 3-55. igVL. 3-55=91) 30. AMPHIBOLE.* Hornblende. Monoclinic. C= 75° 2', 7a /= 124° 30', (9 A 1-1= 164° 10', c\l\ d =0-5527 : 1*8825 : 1. Crystals sometimes stout, often long and Idaded. Cleavage: / higblj perfect; i-i, i-l sometimes distinct. Latei-al planes often longitudinally striated. Twins: twinning-plane ^-^, asin f. 527 (simple form f. 526), and 530. Impei-fect crystallizations : fibrous or columnar, coarse or fine, fibres often like flax; sometimes lamellar; also granular massive, coarse or fine, and usually strongly coherent, but sometimes friable. 624 528 526 ^My i) H.=5-6. G.=2-9-3'4. Lustre vitreous to pearly on cleavage-faces; fibrous varieties often silky. Color between black and white, through vari- ous shades of green, inclining to blackish-green. Streak uncolored,or paler than color. Sometimes nearly transparent ; usually subtranslucent — opaque. Fracture subconchoidal, uneven. Bisectrix, in most varieties, inclined about 60° to a normal to 0, and 15° to a normal to ^-^; and double refraction negative. Comp., Var. — General formula RSiOa, as for pyroxene. Aluminum is present in mobt amphibole, and when so it usually replaces silicon. 11 may correspond to two or more of the basic elements Mg.Ca.Fe.Mn.Nao.KjJI.; and H to .Vl, Fe or Mn. Fe sometimes replaces Bilicou, like Al. Much amphibole, especially the aluminous, contains some fluorine. The base calcium is absent from some varieties, or nearlj' so. The varieties of amphibole are as numerous as those of pyroxene, and for the same reasons; and they lead in general to siuiilar subdivisions. OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 297 T. Containing little or no Alumina. il^y Magnesui-J^tme Ainp/iibo/e ; Tremolitb. Grammatite. Colors white to dark-graj. In distinct crystals, either long bladed or short and stout ; long and thin columnar, or fibrous ; also compact granular massive. 7 A 7^=124^ 30'. H. =50-6 5. G.=:2 9-3-1. Sometimes transparent and colorless. Contains magnesia and lime with little or no iron ; formula (Ca, MgjSiOa, Ca : Mg=l : 3=:Sillca 57-70, magnesia 28 85, lime 13-35 = 100. Named Trenwlitehy Pini, from the locality at Tremola in Switzerland. Nephrite. — In part a tough, compact, fine grained tremolite, having a tinge of green oi blue, and breaking with a splintery fracture and glistening lustre. H.=6-G"5. G.=296-3-l. Named from a supposed efficacy in diseases of the kidney, from vE lbs., making it in all nearly 2-^ tons. Other localities are in ilTuss., at Barre ; at Goshen; at Chesterfield. In Conn., at Haddam; Middletown ; at Madison. In Pcnn., at Leiperville and Chester ; at Mineral Hill. EUDIALYTE. — Rhombohedral. Color rose-red. E.Kact composition uncertain. Analysis, Damour, SiOo 50-38, ZiO, 15-60, Ta.Oj 0-85, FeO (J-37, MnO l-(il, CaO 9 23, Na,0 13-10, CI 148, HjO 1-25 = 99-37. West Greenland. Eucolite is similar, but contains also some of the cerium metals. Norway. PoLLUCXTE.*— 3R.rklSi,0,o-f2aq with R, = mostly Cs(Na,Li). If Na : C8=l : 2, then SiO., 42 G, AlO. 18-2, Cs,0 33 4, NasO 3-7, H,0 2-1 = 100. Isocetric. Colorless. Island ol Elba with castcrite. 300 DESCRIPTIVE MINEKALOGY. /J. Unisilioates. General Formula EuSi04. xy Chrysolite Grroiqy. CHRYSOLITE.* OUvine. Peridot. Orthorhombic. /A 7=94° 2'; 533 534 HtOF OM-l =128° 28' : c:l:d:= 1-2588 ; 1'072'J : 1. Oh. 1-i =z 130° 26^'. ii A ^■-9, ov. i-l, = 130" 2'. Cleavage : i-i rather distinct. MasE-ive and compact, or i^raiiular; usually in imbedded grains. H. = 6-7. G.=3-33-3-5. Lustre vitreous. Color green — commonly olive-green, sometimes yellowj brownish, grayish-red, grayish- green. Streak usually uncolored, rarely yellowish. Transparent — translucent. Fracture conchoidal. Comp., Var. — (Mg,Fe)2Si04, with traces at times of Mn, Ca, Ni. The amount of iron varies much. If Mg : Fe=12 : 1, the formula requires Silica 41 39, magnesia 50*90, iron protoxide 7-71=100 ; Mg : re=9 : 1, 6 : 1, etc., and in hyalosiderite 2 : 1. Pyr., etc. — B.B. whitens, but is infusible ; with the fluxes gives reactions for iron. Hya- losiderite and other varieties rich in iron fuse to a black magnetic globule. Some varietiea jive reactions for titanium and manganese. Decomposed by hydrochloric acid with separa- tion of gelatinous silica. Diif. — Distinguished by its infusibility. Commonly observed in small yellow imbedded grains, Obs. — A common constituent of some eruptive rocks ; and also occurring in or among meta- morphic rocks, with talcose schist, hypersthene rocks, and serpentine ; or as a rock formation ; also a constituent of many mettorites {e.g.., the Pallas iron). Occurs in eruptive rocks at Vesuvius, Sicily, Hecla, Sandwich Islands, and most volcanic islands or regions ; in Auvergne ; at Uukel, on the Rhine ; at the Laacher See ; in dolerite or basalt in Canada. Also in labradorite rocks in the White Mountains, N. H. {hyaloaklerite) \ in Loudon Go./ Va:; in Lancaster Co., Pa., at Wood's Mine. The following are members of the Chrysolite Group : FoRSTERiTE. — Mg..Si04. Like chrysolite in physical characters. Vesuvius. BoLTONlTE, essentially the same. Bolton, Mass. MoNTiCKLLiTE, from Mt. S'mma, and Batraciiite, from the Tyrol, are (Ca,Mgj.,Si04, with Ca : Mg=l : 1. H. =5-5'5. G. =303-3-25. Monticellite also occurs in large quantitiefl (v. Rath) on the Pesmeda Alp, Tyrol, altered to serpentine and fassaite. (^ Fayaijte. — FejSiOj, G. =4-414. Color black. In volcanic rocks at Fayal, Azores ; Mourne Mts., Ireland. HoRTONOLiTE.— (Fe,Mg)..Si04, with Fe : Mg=3 : 2. O'Neil mine. Orange Co., N. Y. m. Tepiihoite- — Mn..Si04. G. =4-4' 12. Color reddish-brown. Sterling Hill, N. J. ; Sweden. Roepperite. — An iron-manganese-zinc chrysolite. H. =5-5-6. G.=3"9o-4-08. Color dark-green to black. Stirling Hill, N. J. Knebelite.— (Fe,Mn).,Si04, with Fe : Mn=l : 1. G. =4-12. Color gray. Dannemora. Leucophanite.* — Composition given by the analvsis (liamm.) SiOa 47*03, AlOa 1 03, BcO 10-70, CaO 23-37, MgO 0*17, Na.O 11*26, K,0 0-30, F 0*57=100-43. Orthorhombic. G. = 2 97. Color greenish-yellow. Occurs in syenite on the island of Lamoc, Norway. Meliphanite (Melinophan).— Composition given by the analysis (Ramm.) SiOj 43-66, 2V103(FeO,) 1-57, BeO 11-74. CaO 2(r74, MgO 11, Na,0 8 55, K.O 140, H.,0 030, F 5*73 =99*80. G. =3-018. Orthorhombic. Color yellow. Fredriksviirn, Norvva/. Woxilerite. — Composition given by the analysis (Ramm.) SiOj 28*43, CboOs 14-41, ZrOi 19-03, CaO 20-18, FeO(MnO; 2 50, Na.,0 778=98 9.3. Monoclinic. G.=3-41. Color light- yellow. Near Brevig. Norway. OXYGEN COMPOUNDS — ANHTDK0U8 SILICATES. 301 Willemite Group. \J WILLEMITE. Rhombohedral. BaB = 116° 1',0aB = 142° 17' ; c = 0-67378. age: i-2 easy in N. Jei-sey crystals; O easy in those of Moresiiet. massive and in disseminated grains. Sometimes fibrous. H. = .5-o. G. = 3-S9-4-18; 4-27, transparent crystals (Cornwall). Lnstre vitreo-resinous, rather weak. Color Cleav. Also whitish or greenish-yellow, when purest ; apple-green, flesh-red, grayish-white, yellowish-brown ; often dark- brown when impure. Streak nncolored. Transparent to opaque. Brittle. Fracture conchoidal. Donble refraction strong ; axis positive. Var. — The crystals of Moresnet and New Jersey dififer in occurring forms. The latter are often quite large, and pass under the name of troostite ; they are commonly impure from the presence of man- ganese and iron. Comp.— ZnoSi04=Silica 27-1, zinc oxide 72-9=100. Pyr., etc. — B. B. in the forceps glows and fuses with difficulty to a white enamel ; the varieties from New Jersey fuse from 3 '5 to 4. The powdered mineral on charcoal in R.F. gives a coating yellow while hot and white on cooling, which, moistened with solution of cobalt, and treated in O. F., is colored bright green. With soda the coating is more readily obtained. Decomposed by hydrochloric acid with separation of gelatinous sUica. Obs. — From Vieille-Montagne near Moresnet ; also at Stolberg; at Raibel in Carinthia; at Kucsaina in Servia, and in Greenland. In New Jersey, at both Franklin and Stirling in such quantity as to constitute an important ore of zinc. It occurs intimately mixed with zincite and franklinite, and is f oimd massive of a great variety of colors, from p£de honey- yellow and light green to dark ash-gray and flesh-red ; sometimes in crystals {troostite). DIOPTASE. Emerald- Copper. Rhombohedral; tetartohedral. Ji A B =126° 24' ; OkR- 148° 38' ; c= 0-5281. Cleavage: R perfect. Twins: twinuing- plane R. Also massive. H. = 5. G. = 3-27S-3-348. Lustre vitreous. Color emerald-green. Streak green. Transparent — subtrans- // ^\^ 4 lucent. Fracture conchoidal, uneven. Brittle. Double refraction strong, positive. Comp.— Q. ratio for Cu : Si : H=l : 2 : 1 ; formula H.CuSiOi (Ilamm.) = Silica 38'1, copper oxide 50'4, water 11 •5 = 100. Pyr., etc. — In the closed tube blackens and yields water. B. B. decrepitates, colors tue flame emerald-green, but is infusible. With the fluxes gives the reactions for copper. With soda on charcoal a globule of metallic copper. Decompoped by acids with gelatinization. Obs. — Dioptase occurs disposed in well-defined crystals and amor- phous on quartz, occupying seams in a compact limestone west of the hill of Altyn-Tubeh in the Kirghese Steppes ; also in the Siberian gold-washings. From Chase Creek, near Clifton. Arizona, in fine crystals, on a " mahogany ore," consisting of limonite and copper oxide. PHENACiTE.—BeoSiOj.' Rhombohedral. Colorless. Resembles quartz. Takovaja; Durango, Mexico. Miask ; 302 DESCRIPTIVE MINERALOGY. Fkiedelite. — Ehombohedral. a 72=147"; i?Ai2=123° 42'. Cleavage: easy, n.— 4.75. G.=3.07. Also massive, saccharoidal. Color rose-red. Translucent. Doable refraction strong, axis negative. Analysis, SiOo 36.12, MnO (FeO tr) 53-05, MgO, CaO 2-96, HjO 7"87=100 This corresponds to the formula Mn4Si30io+2H..O. Tf the water is basic 8s in dioptase, with which it seems to be related in form, the formula is H4Mn4Si30ii = U,Si04. This requires SiO-, 3600, MuO 5680, H,0 720=100. ^ Occurs with diaUogite and alabandite at the manganese mine of Adervielle, Hautes-Pyrenees. (Bertrand, C. R. , May, 1876.) L-n^t-'c/i," HELVITE.* Isometric: tetraliedral. Cleavage: octahedral, in traces. H.=6-G-5. G. = 3*l-3-3. Lustre vitreous, inclining to resinous. Color Iionej'-yellow, inclining to vellowish-brown, and siskin-green. Streak un- colored. Subtranslucent. Fracture uneven. Comp.— Q. ratio for R : Si=l : 2 ; for Mn + Fe : Be = l : 1 ; formula 3(Be.Mn,Fe).2Si04-(- (Mn.FejS (Ramm.). Analysis by Teich, Lupikko, Finland, SiC, 30-31, BeO 10-51, MnO ;!7 87, FeO 10-37, CaO 4-72, ign 022, S 5-95=99 -95. Pyr., etc. — Fuses at 3 in R.F. with intumescence to a yellowish-brown opaque bead, becom- ing darker in R.F. With the fluxes gives the manganese reaction. Decomposed by hydro- chloric acid, with evolution of sulphuretted hydrogen, and separation of gelatinous silica. Obs. — Occurs in gneiss at Schwarzenberg in Saxony ; at Breitenbrunn, Saxony ; at Horte- kulle near Modum, and also at Brevig in Norway, in zircon-.syenite. ^yy^ DANALITE.* Isometric. In octahedrons, with planes of the dodecahedron ; the dode- cahedral faces striated parallel to the longer diagonal. H. = 5-5-6. G. = 3*427. Lustre vitreo-resinons. Color flesh-red to gray. Streak similar, but lighter. Ti-anslucent. Fracture subconchoidal, uneven. Brittle. Oomp 3(Be,Fe,Mn,Zn)2Si04-H(Fe,Mn,Zn)S. Analysis : J. P. Cooke, Rockport, SiOj 81-73, FeO 27-40, MnO 6 28, ZnO 17-51, BeO 13-83, S 5 -48= 102 23. By subtracting from the analysis oxygen 2-74, equivalent to the sulphur, the sum is 99-49. Pyr., etc. — B.B. fuses readily on the edges to a black enamel. With soda on charcoal gives a slight coating of zinc oxide. Perfectly decomposed by hydrochloric acid, with evolution of sulphuretted hydrogen and separation of gelatinous silica. Obs.— Occurs in the Rockport gi-anite. Cape Ann, Mass., small grains being disseminated through this rock ; also near Gloucester, Mass. EuiiYTiTK (Kieselwisnuth, fferyw.).— Isometric, tetrahedral ; in minute crystals often aggregated together. H. =4-5-5. 6. =6*106. Color grayish-white to brown, t'wi/). A uni- silicate of bismuth, BijSiaOi^. Schneeberg. AgncoUte. Composition similar, but form monoclinic. Occurs in globular masses having a radiated structure, and in indistinct groups of crystals. Schneeberg (color hair-brown) and Johanngeorgenstadt (color wine-yellow). BiSMOTOFEUUiTE. — Cryptocrystalline ; generally massive. H. =3 5. G. =4-47. Color olive-green. Analysis (Frenzel) SiOa 24 05, FeOa 33-12, BioOa 42 83 = 100. Schneeberg. Hypochlorite is homstone mixed with the above mineral and other impurities. GarTiet O-roup. GARNET.* Granat, Oerm. Isometric; dodecahedron, f. 537, and the trapezohedron 2-2, f. 538, tlie most common forms; octahedral form very rare. Distorted forma OXYGEN COMPOUNDS — ANUTDKOUS SILICATES. 303 shown in f. 345-352, pp. 105, 106. Cleavage : dodecahedral, sometimes quite distinct. Twins: twinning-plane octahedral. Also massive; granular, coarse, or fine, and sometimes friable ; lamellar, lamellae thick and bent. Also very compact, crypto-crystalline like saussurite. r)87 539 540 H.=6-5-7"5. G.=3'15-4-3. Lustre vitreous — resinous. Color red, brown, yellow, white, apple-green, black ; some i-ed and gi-een colors often bright. Streak white. Transparent — subtrauslucent. Fracture snbcon- choidal, uneven. Brittle, and sometimes friable when granular massive; very tough when compact cryptocrystalline. Sometimes doubly refracting in consequence of lamellar structure, or in some cases from alteration. Comp., Var. — Garnet is a unisilicate of elements in the sesquioxide and protoxide state*, having the general formula RsftSisOii. There are three prominent groups, based on the nature of the predominating sesquioxide. I. AliUxitNA GARNET, in which aluminum (Al) predominates. II. Iron gabnet, in which iron (Fe) predominates, usually with some aluminum. III. CUKOME GARNET in which chromium (6r) is most prominent. There are the following varieties or subspecies, based on the predominance of one or anothei ^ of the protoxides : ^ A. (tKossularite, or Lime- Alumina garnet. B. Pyrope, or Magnesia- Alumina garnet. C. Almandite, or Iron- Alumina garnet. D. Spessartitk, or Manganese- Alumina garnet, E. Andradite, or Lime-Iron garnet, including 1, ordinary; 2, manganesian, ox RjtJiofflte ; 3, yttriferous, or Ttter-garnet. F. Bredbergite, or Lime- Magnesia- Iron garnet. G. OUVAROVITE, or Lime- Chrome garnet. Excepting the last, these subdivisions blend with one another more or less completely. A. Lime- Alumina gar net ; Grossularite. Cinnamon stone. A .silicate mainly of aluminum and calcium ; formula mostly CaaAlSiaOi 2 = Silica 40'0, alumina 2:i"8, lime o7-2 = 100. But some calcium often replaced by irou, and thus graduating toward the Almandite group. Coloi (a) white; {h) pale green ; (c) amber- and honey-yellow; {d) wine-yellow, brownish-yellow, cinnamon- brown; rarely {e) emerald-green from the presence of chromium. G. =3'4-3'75. B. Mr gnesia- Alumina garnet; Pyropp:. A silicate of aluminum, with various protoxide bases, among which magnesium predominates much in atomic proportions, while in small pro- portion in other garnets, or absent. Formula (Mg,Ca.Fe,Mn)3rtlSi30io. The original pyrope is the kind containing chromium. In the analysis of the .Vi'endul magnesia-garnet, Mg : Ca : Fe-HMn=3 : 1 : 2; SiO, 42-45, AIO3 2247, FeO 29. MnO 0-27. MgO 13 4:J. OaO (i-53=: 100'44 Wacht. G. =3'157. The name ;M/rf>^;e is from -n n,i-u:. Jirr4ike. G. Iron-Alumina garnet ; Almandite. A silicate mainly of aluminum and iron \Fe)'f formula FeaAlSiaOi,^ Silica 3(i"l, alumina 20 fi. iron protoxide 4:5'3=:100; or Mn may re- place some of the Fe, and Fe part of the Al. Color fine deep-red anil tr.mspaient, and then called precious garnet ; also brownish-red and tran.slacent or subtrauslucent, common garnet; black, and then referred to var. melavAte. Part of common garnet belongs to the AndradiU group, or is iron garnet. 304 DESCRIPTIVE ^nNERU>OGY. D. Manganese- Ahimina garnet; Spessaktite. Color dark hyacinth-red (fr. Spessart), sometimes with a shade of violet, to brownish-red. G-. =3'7-4'4. Analysis, Haddam, Ct., SiOi 36-16, Al.Oa 19-7(5, FeO 11 10, MnO 3218, MgO 0-2-2, CaO 0-58=100, Ramm. E. Lime-Trvn gnrnct ; Andraditk. Aplome. Color various, including wine-, topaz , and greenish-yellow (topazolite), apple-green, brownish-red, brownish-yellow, grayish-green, dark green, brown, grayish-black, black. G. =3.64-4. Comp. — Casl^eSiaOio, this includes : («) Topazolite, having the color and transparency oi topaz, and also sometimes green ; although resembling essonite, Damour has shown that it belongs here, (b) Colophonite^ a coarse granular kind, brownish-yellow to dark reddish- brown in color, resinous in lustre, and usually with iridescent hues ; named after the resin eolopliony. {c) Mekmite (named from f.i^ac, black), black, either dull or lustrous; but all black garnet is not here included. Pi/feneite is grayish-black melanite ; the original afforded Vauquelin 4 p. c. of water, and was iridescent, indicating incipient alteration, (d) Dark green garnet, not distinguishable from some allochroite, except by chemical means. P. Lime-Mitg/iesia Iron garnet; Bkedbergite. A variety from Sala, Sweden, is here included. Formula (Ca.Mg)3FeSi30i2 = Silica 37-2, iron sesquioxide 33-1, magnesia 12*4, lime 17"3 = 100. It corresponds under Iron garnet nearly to aplome under Alumina garnet. G. Lime-Chrome garnet ; Ouvauovite. A silicate of calcium and chromium. Formula Cas^rSisOio. In the Ural variety, a fourth of the chromium oxide is replaced by aluminum oxide; that is, Al : €r=l : 3 nearly. Color emeni Id-green. H.=7-5. G. =3'41--3*53. B.B. infusible; with borax a clear chrome-green glass. Named after the Russian minister, Uvarof. Pyr., etc.— Most varieties fuse easily to a light-brown or black glass ; F. =3 in almandite, Bpessartite. grossularite, and allochroite ; 3oinpyrope; but ouvarovite is almost infusible, F.=6. Allochroite and almandite fuse to a magnetic globule. Reactions with the fluxes •vary with the bases. Almost all kinds reaet for irou ; strong manganese reaction in spessar- tite, and less marked in other varieties ; a chromium reactiou in ouvarovite, and in most py- rope. Some varieties are partially decomposed by acids ; all except ouvarovite are decomposed afterignition by hydrochloric acid, and generally with separation of gelatinous silica. Decom- posed on fusion with alkaline carbonates. Difif. — Ordinary garnets are distinguished from zircon 'by their fusibility B.B., but they fuse less readily than vesuvianite ; the vitreous lustre, absence of pi isiuatic structure, and usually the form, are characteristic ; it has a higher specific gravity tl an tourmaline. Obs. — Garnet crystals are very common in mica schist, giuiss. syenitic gneiss, and horn- blende and chlorite schist ; they occur often, also, in granite, .>-yenite, crystalline limestones, sometimes in serpentine, and occasionally in trap and volcanic tufa and lava. Some localities are: Cinnainon-stoae {Esaonite), Ceylon; Mussa-Alp in Piedmont. Grossularite, Siberia; Tellemark, Norway; Ural. Aliud/tdite, Ceylon. Pegu, Brazil, and Greenland. Common garnet in large dodecahedrons, Sweden ; Arendal and Kongsberg in Norway, and the Zillerthal. Mtlauite at Vesuvius ai^d in the Haiites-Pyreneea {Fyreneite). Aplome a.t Schwarzenberg in Saxony. Spessartite at Spessart in Bavaria, Elba, at St. Marcel, Piedmont. Pyrope in Bohemia, also at Ziiblitz in Saxony. Oiivarociti- ai the Urals. In N. America in Maine. Phippsburg, Rumford, Windham, at Brunswick, etc. In N. JIamp., Warren. In Mass., at Carlisle; massive at Newbury; at Chesterfield. In Conn., trapezo- hedrons, +-1 in. , in mica slate, at Reading and Monroe ; Haddam. In N. York, at Roger's Rock; Crown Point, Essex Co.; at Amity. In N. Jersey, at Franklin. In Penn., in Chester Co., at Pennsbary ; near Knauertown, at Keims' mine ; at Chester, brown; in Leiperville, red; near Wilmington. In California, in Los Angeles Co., in Mt. Meadows; ouvarovite at New Idria ; pyrope, near Santa Fe, New Mexico. In Canada, at Mannora, at Grenville ; chrome -garnet in Orford, Canada. The cinnamon- stone from Ceylon (called hyacinth) and the precious garnet are used as gems when large, finely colored, and transparent. The stone is cut quite thin, on account of the depth of color, with a pavilion cut below, and a broad table above bordered with small facets. An octagonal garnet measuring %\ lines by 6^ has sold for near $700. Pulverized garnet is sometimes employed as a substitute for emery. J Vesuvianite Group, zmooN.* Tetrai^onal. C> A 1-^ = 147° 22'; c = 0-640373, Haidinger.^ /a1 = 132° 10^ Faces of pyramids sometimes, con vex. Cleavage: /imperfect, 1 less distinct. Also in irregular forms aiid grains. OXTGEN COMPOUNDS — AJ!rUTUKOUS SILICATES. 305 H. = 7-5. G.=4-05-4-7o. Lustre adamantine. Colorless, pale yellow- ish, grayish, yellowish-green, brownish-yellow, reddisii-brown. Streak un colored^ Transparent to subtranslncent and opaque. ^ ' "^"' l)rilliaut. Double refraction strong, positive. Fracture conchoidal 545 546 Saualpe. McDowell Co., N. C. Var. — The colorless and yellowish or smoky zircons of Ceylon have there been long called jargons in jewelry, in allusion to the fact that, while resembling the diamond in lustre, they were comparatively worthless ; and thence came the name zircon. The brownish, orange, and reddish kinds were called distinctively hyaciatJis — a name applied also in jewelry to some topaz and light-colored garnet. Comp ZrSiO 4= Silica a3, zirconia 67=100. Klaproth discovered the earth zirconia in this species in 1TS9. Pyr., etc.— Infusible ; the colorless varieties are unaltered, the red become colorless, while dark-colored varieties are made white ; some varieties glow and increase in density by igni- tion. Not perceptibly acted upon by salt of phosphorus. In powder is decomposed when fused with soda on the platinum wire, and if the product is dissolved in dUute hydrochlorio acid it gives the orange color characteristic of zirconia when tested with turmeric paper. Not acted upon by acids except in fine powder with concentrated sulphuric acid. Decomposed by fusion with alkaline carbonates and bisulphates. Diff.— Distinguished by its adamantine lustre, hardness, and infusibiiity ; the occurrence of square prismatic forms is also characteristic. Obs.— Occurs in crystalline rocks, especially granular limestone, chloritic and other schists ; gneiss, syenite ; also in granite ; sometimes in iron-ore beds. Found in alluvial sands in Ceylon ; in the gold regions of the Ural ; at Arendal in Norway ; at Fredericksviim, in zircon -syenite ; in Transylvania ; at Bilin in Bohemia. In N. America, in N. York, at Moriah, Essex Co. , and in Orange Co. ; in Warwick ; near Amity ; at Diana in Lewis Co. ; also at Rossie. In iV. Jersey, at Franklin ; at Trenton in gneiss. In N. Car., in Buncombe Co.; in the sinds of the gold washings of McDowell Co. In CaUfaraia,, in the auriferous gravel of the north fork of the American river, and else- where. In Canada, at Grenville, etc. / VESUVIANITE.* Idocrase. Tetragonal. O A \-i = 151° 45' ; c = 0-537199 (v. Kokscharof). O A 1 = 142° 46^' 1 A 1, ov. l-^■, = 129° 21'. Cleavage : / not very distinct, O Btill less so. Columnar structure rare, straight and divergent, or irregular. Sometimes granular massive. Prisms usually terminating in the basal plane O; rarely in a pyiamid or zirconoid; sometimes the prism nearly wanting, and the form short pyramidal with truncated summit and edges. 20 306 DESCRIPTIVE MINERALOGY. n.=6-5. G.=3-349-3-45. Lustre vitreous iiious. ; often /Color inclining brc»wu to to re- green, and the latter frequently bright and clear ; occasionally sulphur- yellow, and also pale blue ; some- times green along the axis, and pistachio-green transversely. Streak white. Subtransparent — faintly subtranslucent. Fracture subconchoidal — uneven. Double refraction feeble, axis negative. Comp., Var,— Q. ratio for R : K : Si= 4:3:7 (according to the latest investi- gations of Rammelsberg). R=Ca (also Sandford, Me. Mg, Fe, or K^X^, Naj); ft= Al and also Fe. If we neglect the water the empirical for- mula is ReRiSiiOos, where the quantivalent ratio of bases to silicon is 1 : 1. The ratio of R : ft varies much, which, as stated by Rammelsberg. is the explanation of the different varieties. Analyses by Rammelsberg. (1) Monzoni ; (2) Wilui, Siberia. Yi^' ^^3^ SiOo AlOs FeOa FeO MgO CaO Na.O(K.O) H.O (1) 37;52 16 08 3-75 2 91 2-11 3o-34 lU 2-08= 99-75 (a) 38-40 13-72 6-54 6-88 3504 06 0.82=101-06 Pyr., etc. — B.B. fuses at 3 with intumescence to a greenish or brownish glass. Magnaa states that the density after fusion is 2-93-2 945. With the fluxes gives reactions for iron, and a variety from St. Marcel gives a strong manganese reaction. Cyprine gives a reaction for copper with salt of phosphorus. Partially decomposed by hydrochloric acid, and completely when the mineral has been previously ignited. Diff. — Resembles some brown varieties of garnet, tourmaline, and epidote, but its tetragonal form and easy fusibility distinguish it. Obs. — Vesuvianite was first found among the ancient ejections of Vesuvius and the dolo- mitic blocks of Somma. It has since been met with most abundantly in granular limestone ; also in serpentine, chlorite schist, gneiss, and related rocks. It is often associated with lime- garnet and pyroxene. It has been observed imbedded in opal. Occurs at Vesuvius ; at Ala, in Piedmont ; at Monzoni in the Fassathal ; near Christiansand, Norway ; on the Wilui river, near L. Baikal ; in the Urals, and elsewhere. In N. America, in Maine at Phippsburg and Rumford, abundant; Sandford (f. 551). In N. York, at Amity. In ^V. Jersty, at Newton. In Canadd, at Calumet Falls ; at Grenville. Melilite from Capo di Bove, and Hdmboldtimte from Mt. Somma, are similar in com- position. Analysis of the melilite by Damour. SiO . 38-34, iVlOa 8 01, FeOs 1002, CaO 3205, MgO 6-71, NaoO 2-12, K,0 1-51=99-30. Tetragonal. Color honey-yellow. Epidote Groujp. The species of the Epidote Group are characterized by high speciiic gravity, above 3 ; hardness above 5; fusil)ility B.Il below 4: ; anisometric crystallization, and therefore biaxial polarization ; the dominant piismatic angle 112° to 117"^ ; fibrous forms, when they occui-, always brittle ; colors white, gray, brown yellowish green, and deep green to black, and some- times reddish. The prismatic angle in zoisite and other orthorhombic species is 1 1\ T \ but in epidote it ia the angle over a horizontal edge between the planes and ^-^, the orthodiagonal of epidote corresponding to the vertical axis of zoisite, as explained under the latter species. OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 307 V SPIDOTE, Pistazite. Moiioclinic. 6"= 89° 27' ; i-^ A ^2 = 63° 8', 6> A l-l = 122" 23'; c:h\a = 0-4S436 : 0-30719 : 1. 0^ 1-i = 154° 3', O A -l-i = 154° 15', i-i A —1 = 10i° 48', i-iM = 104° 15'. Crystals usually leugtheuecl in the direc- tion of the orthodiagonal, or parallel to i-i; sometimes loni^ acicular. Cleavage: i-i perfect; l-i less so. Twins: twinning-jilanc l-i; also i-i. Also fibrous, divergent, or parallel ; also granular, particles of various sizes, Bometimes fine granular, and forming rock-masses. 652 H.=:6-7. G.=3*25-3'5. Lustre vitreous, on i-i inclining to pearly or resinous. Color pistachio-green or yellowish-green to brownish -green, greenish-black, and black ; sometimes clear red and yellow ; also gray and grayish-white. Pleochroism often distinct, the crystals being usually least yellow in a direction through l-i (see p. 166). Streak uncolored, grayish. Subtraiisparent — opaque ; generally subtranslucent. Fracture uneven. Brittle. Var. — Epidote has ordinarily a peculiar yellowish-gTeen (pistachio) color, seldom found in other minerals. But this color passes into dark and light shades — black on one side, and brown on the other. Most of the brown and nearly all the gray epidote belongs to the species Zoisite ; and the reddish-brown or reddish-black containing much oxide of manganese, to the species Piedmontite, or Manganepidot ; while the black is mainly of the species Alkmite, or Cerium-epidote. Oomp. — Quantivalent ratio for Ca : -R : Si = 4 : 9 : 12, and H : Ca=l : 4. The formula is then H:;Ca4tt3Si60.6. H is ¥e or Ah the ratio varying from 1 : 2 to 1 ; 6. Analysis^ Unter- Bulzbach, Tyrol, by Ludmg : SiO, ;J7-8:{, rUO., 22(j;>, FeO-, 15 05, FeO 0-93, CaO 23 -37, H.oO 2 -05 = 100 76. As first shown by Imdwig, eijidote contains about 2 p. c. water, which is given off only at high temperatures. Pyr., etc. — In the closed tube gives water at a high temperature. B. B. fuses with intumes- cence at 'S-o 5 to a dark brown or black mass which is generally magnetic. Reacts for iron and sometimes for manganese with the fluxes. Partially decomposed by hydrochloric acid, but when previously ignited, gelatinizes with acid. Decomposed on fusion with alkaline car- bonates. Diif. — Distinguished often by its peculiar yellowish-green color ; yields a mngnetic globule, B. B. Prismatic forms often longitudinally striated, but they have not the angle, cleavage, or brittleness of tremolite. Obs, — Epidote is common in many crystalline rocks, as syenite, gneiss, mica schist, horn- blendic schist, serpentine, and especially those that contain the ferriferous mineral horn- blende. It often accompanies beds of magnetite or hematite in such rocks. It issometimea found in geodes in trap ; and also in sandstone adjoining trap dikes, where it has been formed by metamorphism through the heat of the trap ai the time of its ejection. It also occurs at times in nodules in different quartz-ro ks or altered sandstones. It is associated often with quartz, pyroxene, feldspar, axinite, chlorite, etc., in the Piedmontese Alps. Beautiful crystallizations come from Bourg d'Oisans, Ala, and Traversella, in Piedmont , Zennatt and elsewhere in Switzerland ; Monzoni in the Fassathal ; the Untersulzbachthal and Zillerthal in the Tyrol. In N. America, occurs in Mass., at Chester ; at Athol ; at Rome. In Conn,, at Hn4dani. 308 DESCKIPTIVE MINKKALOGY. In JV; York, at Amity ; near Monroe. Orange Co. ; at Warwick. In N. Jersey, at Franklin In Penn., at E. Bradford. In Michigan, in the Lake Superior n.gion. li^' Canada, at St Joseph. PiEDMONTiTE (Manganepidot, Oer7n.).—A manganese epidote ; formula, Il.Ca.ftaSicO-.e, with R principally Mn (also iil,Fe). Color reddish-browTi. St. Marcel, Aosta valley, Pied- Uiont. L/ ALLANITE. 555 Ai_ Monoclinic, isomorplious with epidote. C = 89° 1' ; Oa1-1= 122° 60y, i-2 A i-2 = G3° 58' ; c : b : d~ 0-483755 : 0-312187 : 1. Crystals either short, flat tabular, oi- long and slender, soinetinies acicular. Twins like those of epidote. Cleav- age: i'i in ti-aces. Also massive, and in angular or rounded grains. II. = 5-5-(]. G. = 3-0-4-2. Lustre sulnnetallic, pitchy, or resinous — occasionally vitieous. Color pitch- brown to black, either brownish, greenish, grayish, or yellowish. Streak fray, sometimes slightly greenish "or In-owinsh. Subtiiinslucent — opaque, 'racture uneven or subconchoidal. Bi-ittle. Double j-efraction either dis- tinct, or wanting. Vax.—AUanite [Cerine). In tabular crystals or plates. Color black or brownish-black. Gr.=3-50-3-95; found among specimens from East Greenland, brought to Scotland by C. Giesecke. Bucklandite is anhydrous allanite in small black cry.stals from a mine of magnetite near Arendal, Norway. Referred here by v. Rath on the ground of the angles and physical characters. Orthite. Including, in its original use, the slender or acicular prismatic crystals, often a foot long, containing some water. But these R-raduate into massive forms, and some orthites are anhydrous, or as nearly so as much of the allanite. The name is from op66s, straight. The tendency to alteration and hydration may be due to the slendeniess of the crystals, and the consequent great exposure to the action of moisture and the atmosphere. II. =5-6. G. =:2-80-ii-75. Lustre vitreous to greasy. Comp. — Not altogether certain, as analyses vary considerably, some showing the presence of considerable water. According to Rammelsberg the Q. ratio for bases to silicon = 1 : 1 (epidote=rl^ : 1). Allanite has then the garnet formula, RaRSi.O.j, where R=Ce(La,Di), Fe(Mn), Ca(Mg), and occasionally Y,Na,,Ko, etc.; R=rVlor Fe. AnaW.si^, allanite (Ramm.), Fredrikshaab, SiOo 3378, AIO3 14-03, FeOj 0-30, FeO 13(33, CeO 12-63, LaO(DiO) 5-07, CaO 12-12, H,0 1-78=100. Pyr., etc. — Some varieties give water in the closed tube. B.B. fuses easily and swells up (F.=2-5) to a dark, blebby, magnetic glass. With the fluxes reacts for iron. Most varieties gelatinize with hydrochloric acid, but if previously ignited are not decomposed by acid. Obs,— Occurs in albitic and common feldspathic granite, syenite, zircon- syenite, porphyrj, white limestone, and often in mines of magnetic iron. Allanite occurs in Greenland ; at Criffel in Scol.'and ; at Jotun Fjeld in Norway ; at Snarum, near Dresden ; near Schmiede- feld in the Thiiringerwald. (Jerine occurs at BastnMs in Sweden. Orthite occurs at Finbo and Ytterby in Sweden ; also at KrageriJe, etc., in Norway ; at Miask in the Ural. In Mass., at the Bolton quarry. In Conn., at Haddam In iV. Ymk. Moiiah, Essex Co.; at Monroe, Orange Co. In N. jersey, at Franklin. In Penn. , at E. Bradford in Chester Co. ; at Ea-ston. Amherst Co., Va. In Canada, at St. Paul's, C. W. MUKOMONTITE and BoDENlTK from Marienberg, Saxony ; and Micuaei.sonxte from Brevig, are minerals related to allanite. V ZOISITE Orthorhombic. /A 7 = 116° 40', Oa1-1 = 131° If ; c : I> : u = 1-1493 1 1. '62125 : 1. Crystals lengthened in the direction of the veitical avis, and OXYGEN COMPOUNDS — ANHYDROUS SILICAIES. 509 Oor, rertically deeply striated or farrowed. Cleavage: i-l very perfect. monly in crystalline masses longitudinally furrowed. Also compact massive. H. = 6-6-5. G.=3-ll-3-3S. Lustre pearly on i-i-, vitreous on surface of fracture. Color grayish-white, gray, yellowish, brown, greenish-gray, apple-green ; also peach-blossom-red to rose-red. Sti'eak uncolor(?d. Transpai-ent to subtranslucent. Double i-efiaction feeble, optic-axial plane i-i ; bisectrix positive, lioniuil to i-l ; DesCl. Cera ilil Var. — LiME-ZoisiTE. 1. Ordinary. Colors gray to white and brown. 2. Hose-red., ov Thulite. G. =I-i"124; fragile; dichro- ism strong, especially in ths direction of the vertical axis ; in this direction reddish, transversely colorless ; from Norway, Piedmont. Sanssurite.^ which forms with smaragdite the euphotide of the Alps, is a lime-soda zoisite. Conip. — A lime-epidote, with little or no iron, and thus differing from epidote. Q. ratix. as in epidote, H : Ca=l : 4, and Ca : IJ : Si = 4 : 9 : 12, whence the formula H Ca4R3Sio02o. Analysis, Ramm., Goshen (G.=y-341) SiO, 40-06, 7MO3 30(57, FeOs 2-45. CaO 23fll, MgO 49, H,:0 2*25 = 99 83. The amount of iron sesquioxide varies from to (i'83 p. c. ; if much more is present, amounting to a sixth atomically nf the protoxide bases, the compound appears to take the monoclinic form of epidote, instead of the orthorhombic of zoisite. Pyr., etc, — B.B. swells up and fuses at 3-3 to a white blebby mass. Not decomposed by acid ; when previously ignited gelatinizes with hydrochloric acid. Obs. — Occurs at Saualpe in Carinthia ; Baireuth in the Fichtelgebirije ; Sterzing, Tyrol; Lake Geneva; Schwarzwald; Arendal, etc. In the United States, found in Vermont, at Willsboro and Montpelier. In Muss.^ at Goshen, Clie.sterfield, etc. In I'nui., in Chester Co ; at Unionville, white ( Unionite). In Tenn.. at the Ducktown copper mines. \/ JADiiiTE is one of the kinds of pale green stones use d in China for making ornaments, and pas.5ing under the general name of jade or nephrite. Mr. Pumpelly remarks that the fdtsui ia perhaps the most prized of all stones among the Chinese. In composition mainly a silicate of aluminum and sodium. In its high specific gravity like zoisite. Gadolinite. — Monoclinic (DesCl.). Color greenish-black. Contains yttrium, cerium, and generallj' beryllium ; though the last is sometimes absent, through alteration (DesCl.). Sweden ; Greenland ; Norway. MosANDRiTE. — A silicate containing titanium, cerium, and calcium. Brevig, Norway. ?v d == 0-66608 557 \f ILVAITE. Lievrite. Tenite. Orthorhombic. 7a I =112° 38', O A l-l = 146° 24' ; a : b 1-5004 : 1. 6> A 1 = 141° 24', O A 2-i = 138° 29'. Lateral faces usually striated longitudinally. Cleavage: parallel to the longer diagonal, indistinct. Also colunniar or com- pact massive. II. = 5-5-6. G.=3-7-4-2. Lustre submetallic. Color iron-black, or dark grayish-black. Streak black, inclining to green or brown. Opaque. Fracture uneven. Brittle. Comp.— Q. ratio, for R-i-R : Si : H=9 : 8 : 1, and for bases, including hydrogen, to silicon 5 : 4 (Stiideler). Sipocz by the analysis of entirely unaltered crystals (G. =4037) from Elba confirms the conclusions of \, j, .Stadeler in regard to the presence of chemically combined water, and ^^f/x^r^ adopts the same formula, viz.: — H2CaoFe4FeSi40iN. This requires: ^-.^Z.^^ .Silica 29-34, iron sesquioxide 19-oG. iron protoxide 35-21, lime 13-69, water 2-20 = 100 ; manganese protoxide is also sometimes present in small quantities. Ran> int'lsberg considered the water as due to alteration. cia DESCRIPTIVE MTNERALOGT Pyr., etc. — B.B. fuses quietly at 2 5 to a black ma^etic bead. With the fluxes reacts foi iron. Some varieties give also a reaction for manganese. Gelatinizes with hj'drochloric acid. Obs. — Found in Elba, and at the mine of Temperino in Tuscany. Also at Fossum and at Skeeu in Norway; in Siberia; near Andreasberg ; near Predazzo, Tyrol; at Schneeberg; at Hebrun in Nassau ; at Kangerdluarsuk in Greenland. Reported as formerly found at Cumberland, R. I.; also at Milk Row quarry, Scmerville Mass. Ardennite (Dewalquite). — Near ilvaite in form. Habit prismatic; vertically striated. Composition given by the analyses, Lasaulx and Bettendorf, SiO> 29-60, AlOs 23 -.50, MnO 2.r88, ¥eO, 1 (iS, CaO 1 Si, MgO 3-38, V,05 9-20, ign. 4 04=9909. Color dark rosin-brown. In thin splinters transparent. Other varieties, of a bright sulphur-yellow color (but opaque and dull), contain arsenic (9-33 p. c. As.Oe) instead of vanadium. Between these two ex- tremes are a series of compounds containing both arsenic and vanaJdium. Lasaulx regards the arsenic-ardennite as having come from the other through alteranon. LocaUty, Ottrez in the Ardennes, Belgium. Roscoelite (p. 367) is another silicate containing vanadium. n/ AXINITE. Triclinic. Crystals usually broad, and acnte-edo;ed. Making m = O, P='I,uz=J%a (bracliyd.) : h (macrod.) : c = 0-49266 : 1 : 0-45112. Cleav age: i-i (v) quite distinct; in otlier directions indistinct. Also massive, lamellar, lamellae often curved : sometimes granular. V Dauphiny, Dauphiny. Cornwall. n. =6-5-7. G. = 3-271, Haidinger; a Cornf^ specimen. Lustre highly glassy. Color clove-brown, plum-blue, and pearl-gray; exhibits trichroism, different colors, as cinnamon-brown, violet-blue, olive-green, being seen in different directions. Streak uncolored. Transparent to subtranslucent. Fracture conchoidal. Brittle. Pyroelectric, with tMX) axes, the analogue (L) and antilogue (T) poles being situated as indicated in f. 558 (G. Rose). Comp. — .Analyses vary. If it contains 2 p. c. water (Ramm.), and if B. replaces Al, then it is a unisilicate with the formula R7ft3Sit,03 , R = Fe,Mn,Ca.]\Ig, and K^, while R = B..,Al (Bo : Al=l : 2). Analysis (Ramm.), Oisans. Dauphine, SiO., 43-46, B.O, 5-61, AlOs 16-33, FeOa 2-80, FeO 678, MnO 2-62, CaO 2019. MgO 173, K.O O'll, H.O 1-45=101 -08. Pyr., etc. — B. P>. fuses readily with intumescence, imparts a pale green color to the O.F. , and fuses at 2 to a dark green to black glass; with borax in O.F. gives an amethystine bead (manganese), which in R. F. becomes yellow (iron). Fused with a mixture of potassium bisul- OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 311 phate and fluor on the platinum loop colors the flame green (boron). Not decomposed by acids, but when previously igiiited, gelatinizes with hydrochloric acid. Obs.— Axinito occurs near Bourg d'Oisans in Dauphiny ; at Santa Maria, Switzerland; at Kongsberg ; in Normark in Sweden ; in Cornwall ; in Devonshire, near Tavistock ; at Phipa- burg, Maine; at Wales, Maine; at Culd Spring, N. Y. \/ Danburite.*— Triclinic. CaB,Si..OB=Silica 488, boron trioxide 28-5, lime 227-100. Occurs with feldspar in imbedded masses of yellow color in dolomite, at Danbury, Ot. V IOLITIj. Cordierite. Dichroite. Orthorhombic. In stout prisms often hexagonal. 1 1\ 60° 50', A \-l =150° 49'. Cleavage : i-l distinct ; i-l and O indistinct. Crystals often transversely divided or foliated parallel with O. Twins : twinning-plane I. Also massive, compact. H. = T-7-5. G. = 2-56-2-67. Lustre vitreous. Color various shades of blue, light or dark, smoky-blue ; pleo- chroic, being often deep blue along the vertical axis, and brownish-yellow or yellowish-gray pei-pendicularto it. Streak uncolored. Transparent — translucent. Frac- ture subcoiichoidal. / = Comp. — Q. ratio for bases and silicon 4 : 5 or 1 : \\. The state of oxidation of the iron is still unascertained, and hence there is uncertainty as to the proportion between the piotoxidea and sesquioxides. The ratio usually deduced for R : R : Si is 1 : 3 : 5. The formula R^K-Sis Oie, which corresponds to this ratio, =, if R=Mg,Fe and Mg : Fe=2 : 1, Silica 494, •dumina 339, magnesia 8 8, iron protoxide 7 '9= 100. Pjrr., etc. — B. B. loses transparency and fuses at 5-5 '5. Only partially decomposed by acids. Decomposed on fusion with alkaline carbonates. Obs. — lolite occurs in granite, gneiss, horublendic, chlorite and hydro-mica schist, and allied rocks, with quartz, orthoclase or albite. tourmaline, hornblende, andalusite, and sometimes beryl. Also rarely in volcanic rocks. Occurs at Bodenmais, Bavaria ; at Ujordlersoak in Greenland ; at Krageroe in Norway ; Tunaberg in Sweden ; Lake Laach. At Haddam, Conn.; at Brimfield, Mass.; also at Richmond, N. 11. Alt. — The alteration of ioUte takes place so readily by ordinary exposure, that the mineral is most commonly found in an altered state, or enclosed in the altered iolite. For the dis- tinguishing characters of the different kinds of altered iolite, see Finite, Fahlunite, etc., under Hydrous Silicates. \J Mica Group.^ The minerals of the Mica group are alike in having (1) the prismatic angle 120° ; (2) eminently perfect basal cleavage, affording readily very thin, tou^h laminae ; (3) potash almost invariably among the protoxide bases and alumina among the sesquioxide ; (4) the crystal tization approxi- mately either hexagonal or orthorhombic, and therefore the optic axis, or optic-axial plane, at riglit angles (or nearly so) to the cleavage surface. Sodium is sparingly present in some micas, and is characteristic of the hydrous species paragonite (p. 354). Lithium, rubidium, and ca^fsium occur in lepidolite, and lithium insomj biotite Fluorine is often present, probably replacing oxygen. Titanium is found .sparingly in several kinds, and is a prominent ingredient of one species, astrophylb te. It is usually regarded as in the state of titanium dioxide replacing silica ; but it is here made basic. 312 DESCRIPrn^E MINEKALOGT. Tlie species of the Mica group graduate into the hydrous micas of the Margaiodite group (p. 331) ; and through these they also approach the foliated species of the Talc and Chlorite groups, especially the latter. V PHLOGOPITE.* Orthorliombic. JaI=V20°, and habit hexagonal. Prisms usually oblong six-sided prisms, more or less tapering, with irregular sides ; rarely, when small, with polished lateral planes. Cleavage basal, highly eminent. Not known in compact massive forms. H. = 2-5-3. G. = 2-78-2-85. Lnstre pearly, often sub- metallic, on cleavage surface. Color yellowish- brown to brownish-red, with often something of a copper-like reflec- tion ; also pale brownish-yellow, green, white, colorless. Transparent to translucent in thin folia. Thin laminje tough and elastic. Optical-axial divergence 3°-20°, rarely less than 5°. Comp. — The bases include magnesium and little or no iron. Q. ratio R : Si-1 : 1. Formula probably (Ramm.) KoMg6AlSi60oo=Smca 4073, alumina 13-93, magnesia 3257, potash 13'77 = l(i0. Pyr., etc. — la the closed tube gives a little water. Some varietiea give the reaction for fluorine in the open tube, while mcst give little or no reaction for iron with the fluxes. B. B. whitens and fuses on the thin edges. Completely decomposed by sulphuric acid, leaving the silica in thin scales. ^ Obs. — Phlogopite is especially characteristic of serpentine and crystalline limestone or dolomite. Occurs in limestone in the Vosges. Includes probably the mica found in limestone at Alt- Kemnitz, near Hirschberg ; that of Baritti, Brazil, of a golden-yellow color, having the optical angle 5° 30' and parallel to the shorter diagonal (Grailichj ; and a brown mica from limestone of Upper Hungary, afEording Grailich the angle 4'-5°. Occurs in New York, at Gouvemeur ; at Pope's Mills, St. Lawrence Co. ; at Edwards ; Warwick; Natural Bridge ; at Sterling Mine, Morris Co., N. J. ; Newton, N. J.; at St. Je- rome, Canada ; at Burgess, Canada West. ASPIDOLITE (v. Kobell). — Approaches in composition a soda-phlogopite. Green. Foliated. Zillerthal, Tyrol. Manganophyllite. — Q. ratio f or R : ft : Si=3 : 1 : 4 (nearly). Foliated like the micas. Color bronze-red. Analysis, Igelstrom, SiO, 38-50, AIO3 H'OO, FeO 3 78, MnO 31-40, CaO 3-20, MgO 1501, K,0(Na20) 5-51, ign. 1-60=100. Paisberg, Sweden. \J BIOTITE.* Hexagonal (?). R hR = 62° 57' (crystals fr. Vesuvius, Hessenberg) ; c = 4:'911126. Habit often monoclinic. Prisms commonly tabular. Cleavage: basal highly eminent. Often in disseminated scales, sometimes in massive aggregations of clea\able scales. H. = 2-5-3. G. = 2-7-3-l. Lustre splendent, and \noYe or less pearly on a cleavage sni'face, and sometimes submetallic when black ; lateral surfaces vitreous when sniDoth and shining. Coloi-s usually green to black, often deep black in thick crystals, and sometimes even in thin lamiuiB, unless the laminae are very thin ; such thin laminae green, blood-red^ or brown by transmitted light; rarely white. OXYGEN COMPOUNDS — AmiYUKOUS SILICATES. 813 Streak uiicolored. Transparent to opaque. Optically uniaxial. Some- times biaxial with slight axial divergence, from exceptional irregularities; but the angle not exceeding 5° and seldom 1°. Oomp., Var. — Biotite is a magnesia-iron mica, part of the aluminum (Al) being replacoi by iron (Fe ), and Fe and Mg existing among the protoxide bases. Black is the prevailing color, but brown to white also occur. The re.sults of analyses vary much, and for the rea-on already stated — the non-determination, in most cases, of the degree of oxidation of the iron ; and the exact atomic ratio for the species and its limits of variation are therefore not precisely understood. The Q. ratio of br#es to siUcon is generally I : 1, that is the formula in general R,Si04, where R=K.(Na,,Li,)Fe,Mg(Ca), or iVl,Fe(,3R=ft). Analyses: 1, Ballyellin; 2, Vesuvius; 3, Portland, Conn. : SiOj AIO3 FeOa FeO CaO MgO K2O Na^O Li.O ign (1) 35 oo 17-08 23-70 5-50 3 68 9-45 0-35 4-30=99-61, Haughton. (2) 40-91 17-79 3-00 7 03 0-30 19-04 9-96 =98-03, Chodnew. (3)^ 135-Gl 20-03 0-13 21-85 llOMnO 5-23 9-69 0-52 0-93 1-87, F 76, TiO^ 146, CI tr.=99-27, Hawes. The above analyses give the ratio of unisilicates, when the water is neglected ; in othera the ratio of 1 : 1 is obtained only when the water is brought into account. Pyr., etc. — Same as phlogopite, but with the fluxes it gives strong reactions for iron. Obs — A common constituent of many volcanic rocks. Fine specimens obtained at Vesu- vius ; L. Baikal; ZiUerthal; Pargas ; Miask ; Sala. Also from Greenwood Furnace, N. Y.j Moriah, N. Y. ; Eastoa, Penn. ; Topsham, Me., etc. The biotite of Vesuvius, according to the optical examination of Hintze, is monocUnic. (See also Tschermak, Min. Mitth., 1876, 187.) \J LEPIDOMELANE. Hexagonal (?). In small six-sided tables, or an aggregate of minute scales. Cleavage : basal, eminent, as in other micas. H.=:3. G. = 3-0. Lustre adamantine, inclining to vitreous, pearly. Color black, with occasionally a leek-green reflection. Streak grayish- green. Opaque, or translucent in very thin laminae. Somewhat brittle, or but little elastic. Optically uniaxial ; or biaxial with a very small axial angle. Oomp. — An iron-potash mica. Q. ratio for bases and silicon 1:1; for R : R, mostly 1 : 3, but varying to 1 to more than 3 ; of doubtful limits, on account of the doubts as to the state of the iron in most of the analyses. Differs from biotite in the smaller proportion of prot- oxides and little Al and Mg, but appears to agree with it in optical characters. Pyr., etc. — B.B. at a red heat becomes brown and" fuses to -a black magnetic globule. Easily decomposed by hydrochloric acid, depositing silica in scales. Analysis. Cooke. Rock- port, Mass., SiO, 39-91," AIO3 16-73, FeOa 1207, FeO 17-48, MnO 0-54, MgO 0-62, K.O 10-66, Na,0(Li.O) 0-59, HoO 150, F 0-45=100. Obs. — Occurs at Persberg in Wermland, Sweden ; at Abborforss in Finland ; in Ireland, ic Donegal and Leinster Cos. ; at Ballyellin, etc. From Cape Ann, Mass. [Anntte). AsTROPHYLLlTE. — Usually in tabular prisiUH. Color bronze-yellow. Analysis, Pisani, SiO; 82-22, TiO. 7-66, MO3 4 32, PeOa 405, PeO 25 48, MnO 10 70, iVlgO 1-37,' CaO 122, Na^O i!-7l, K,0 6-29, HiO 2-01=99-03. Brevig, Norway ; El Paso County, Colorado. J MUSCOVITE. Kaliglimmer, Oerm.* Motioclinic (Tschermak). IaI=.120°. Cleavage: basal eminent, occadioually also separating in fibres parallel to a diagonal. Twins : often observable hy internal markings, or by polarized light ; composition parallel 314 DESCRIPTIVE MINERALOGY. to 1 consisting of six individuals thns united ; sometimes a union of / A l-«' = 156° 14^' ; c = 0-4398. Often hemihedrai in planes 3-3 and i-2 (p. 30). Cleavage: i-i and /rather distinct, but interrupted. Also massive, granular, or with a faint fibrous appearance ; souietinies colun-iiar, H. = 5-6. G. = 2"63-2*8. Lustre vitreous to pearly externally, inclining to resinous; cleavage and cross- fracture surface vitreous. Color white, gra}-, bluish, greenish, and reddish, usually light. Streak uncolored. Transparent — faintly subtranslucent. Fj-acture sub- conchoidal. Brittle. Comp.— Q. ratio for R : R : Si=l : 3 : 4 (R+R : Si=l : 1); formula RRSi,Oe=Ca(NaOrVlSinO,. Analysis, v. Rath. Pargas, SiO^ 45-46. AlO, 3096, CaO 17-22, NasO 2-29, K,0 1-31, H,0 l-29=98-53. Some varieties vary widely from the above ratio. Pyr., etc. — B.B. fuses easily with intumescence to a white blebby glass. Imperfectly de- composed by hydrochloric acid. piff. — Recognized by its square form ; resembles feldspar when massive, but has a charac- teristic fibrcus appearance on the cleavage surface ; it is also more fusible, and has a highe,! Bpecific gravity. Obs. — Occurs in metamorphic rocks ; sometimes la beds of magnetite accompanying lime- stone. Some localities are : Arendal, Norway ; Wermland ; Pargas, Finland ; L. Baikal, etc. In the following those of the wemerite and ekebergite are not yet distinguished. In Mass., at Bolton ; Westfield. In Conn , at Monroe. In iV. York, in Warwick ; in Orange and Essex Co. , etc. In If. Jersey, at Franklin and Newton. In Canada, at G. Calumet Id. ; at Hunterstown ; Grenville. The following are other members of the scapolite group : Sarcolite.— Q. ratio for R : ft : Si=l : 1 : 2. In mmute flesh-red crystals at Mt Somma. P.4RANTHITE.— Q. ratio=l : 3 : 4. Ekebergite. Q. ratio=l : 2 : 4^, containing G-8 p. 0. soda. MizzoNiTE. Q. ratio=l : 2 : 5i-, containing 10 p. c. soda. In cry.stals at Mt. Somma, DrPYRE. Q. ratio=l :2 : 6, andfor Ca : Nai=l : 1. iLvRiALiTE. Q. ratio=l : 2 : 6, and for Ca : Na2=l : 2. ■•{■ r>?'^ ■^^^^'"^ Nejphelite Group. \y J NEPHELITE. Hexagonal. Nepheline. OM — 135° 55' ; c — 0-839. Usual forms si.x-sided and ggg twelve-sided prisms with plane or modified sum- mits. Fig. 569, summit planes of a crystal. Cleav- age : /distinct, (9 iuiperfect. Also massive, com- pact; also thin colunniar. IL = 55-6. G. = 2. 5-2-65. Lustre vitreous — greasy ; a little opalescent in some varieties. Color- less, white, or yellowish ; also when massive, dark- green, greenish or bluish-gray, brownish and biick- red. Transparent — opa(pie. Fracture subcon- choidal. Double refraction feeble: axi:^ negative. Var. — 1. Glossy, or Sommite. Usually in small crystals or grains, with vitreous lustre, first found on Mt. Somma, in the region of Vesuvius. Davyne and eavoiinite belong here. B, ElceoUte. In large coarse crystals, or massive, with a greasy lustre. OXYGEN COMPOUNDS. — ANHYDROUS SILICATES. 317 Comp. — Somf^what uncertain, as all analyses give a little excess of silica beyond what ia required for a unisUicate. Assuming that nephelite is a tru^unisUicate, the Q. ratio for R : ft : Si=l : 3 : 4, and the formula is (Na,K)2AlSi.,0« iRamm.); some of the Naj being replaced by Ca. Analysis, Scheerer, Vesuvius, SiO> 4403, AlOa 33-28, FeOa (MuOs) O'GS, CaO 1-77. Na.O 15-44, K.jO 4-94, H3O 0-21=100-32, The variety Elmlite has the same composition. Pyr., etc. — B.B. fuses quietly at 3 5 to a colorless glass. Gelatinizes with acids. Diflf. — Distinguished by its gelatinizing with acids from scapolite and feldspar, as also from apatite, from which it differs too in its greater hardness. Massive varieties have a character- iatic greasy lustre. Obs — Nephelite occurs both in ancient and modern volcanic rocks, and also metamor^jhic rocks allied to granite and gneiss, the former mostly in glassy crystals or grains {soimnite) , the latter massive or in stout crystals {elmoUte). Nephelite occurs in crystals in the older lavas of Somma ; at Capo di Bove, near Rome ; in doleryte of Katzenbuckel, near Heidelberg, etc. Elaaolite is found in Norway ; in the Ilmen Mts. ; Urals ; at Litchfield, Me. ; in the Ozark Mts. , Arkansas. Named /ie^jAe^me by Haiiy (1801). f rom wi;!)f /.'/, a cloud, in allusion to its becoming cloudy when immersed in strong acid ; elcBoUfe (by Klaproth), from eAaiov, oil, in allusion to its greasy lustre. GiESECKiTE is shown by Blum to be a pseudomorph after this species (see p. 330). ^^ Cancuinite.— Hexagonal, and in six- and twelve-sided prisms, sometimes with basal edges replaced; also thin columnar and massive. H.=5-6. G. =2-42-2-5. Color white, gray, yellow, green, blue, reddish ; streak uncolored. Lustre subvitreous, or a little pearly oi. greasy. Transparent to translucent. Comp. — Same as for nephelite, with some RCO3 and water. Analysis, Whitney, Litchfield, Me., SiO. 37-43, AIO3 2770, CaO 3-91, Na,0 2098, KoO 0-67, CO2 5-95. H.0 2-82, FeOa (MnOa) 0-86=100-31. Pyr., etc. — In the closed tube gives water. B.B. loses color, and fuses (F.=2) with intu- mescence to a white blebby glass, the very easy fusibility distinguishing it readily from nephelite. Effervesces with hydrochloric acid, and forms a jelly on heating, but not before. Obs. — Found at Miask in the Urals; at Barkevig, Norway; at Ditro in Transylvania (ditroyte) ; at Litchfield, Me. v^^ \J SODALITE. Isometric. In dodecahedrons. Cleavage : dodecabedral, more or less distinct. Twins : see f . 272, p. 93. Also massive. H. = 5-5-6. G. = 2'136-2'4:Ul. Lnsti-e vitreous, sometimes inclining to greasy. Color gray, greenish, yellowish, white ; sometimes bhie, lavender- blue, light red. !Snbtransj)arent — translucent. Streak uncolored. Frac- ture couchoidal — uneven. Comp.— 3]SraoA:lSi.,08+2NaCl=SUica 87-1, alumina31-71, soda 25 -55, chlorine 7-31 = 101 65. Home varieties contain considerably less chlorine. Pyr., etc. — In the closed tube the blue varieties become white and opaque. B.B. fusea with intumescence, at 3 -5-4, to a colorless glass. Decomposed by hydrochloric acid, with separation of gelatinous silica. Obs. — Occurs in mica slate, granite, pyenite, trap, basalt, and volcanic rocks, and is often associated with nephelite (or elasolite) and eudialyte. Found in West Greenland ; on Monte Somma; in Sicily; at Miask, in the Ural; near Bre^ ig, Norway. A blue variety occTirs at Litchfield, Me., and at Salem, Mass. MiCRosoMMiTE. — Occurs in very minute hexagonal crystals in masses of leucitic lava ejected from Mt. Somma. Composition : a uuisilicate of potassium, calcium, and aluminum, with small quantities of sodium chloride and calcium sulphate. 318 DESCKIPTIVE MINEKALOGT. ' ^ HAUYNITE. Isometric. In dodecahedrons, octahedrons, etc. Cleavage : dodecahe- dral distinct. Commonly in rounded grains often looking like crystals with a fused surface. H.= 5-5-6. G.=2-4-2-5. Lustre vitreous, to somewhat greasy. Coloi bright blue, sky-blue, greenish-blue ; asparagus-green. Streak slightly bluish to colorless. Subtransparent to translucent. Fracture flat conchoi- dal to uneven. Comp. — 2Na2(Ca)AlSi208-f-CaS04 ; if in the silicate Nas is replaced by Ca, the atomio ratio here being 5 : 1, this gives Silica 3413, alumina 29-18, lime 1062, soda 14-69, sulphui trioxide 11'38,=100. A little potassium is also often present. Pyr., etc.— In the closed tube retains its color. B.B. in the forceps fuses at 45 to a white glass. Fused with soda on charcoal atfords a sulphide, which blackens silver. Decomposed by hydrochloric acid with separation of gelatinous silica. Obs. — Occurs in the Vesuvian lavas, on Somma ; in the lavas of the Campagna, Rome ; in basalt at Niederraendig and Mayen, L. Laach, etc. NosiTE (Nosean). — A soda-hsinjiiite ; 2Na2AlSi208 + NajS04, with also a little calcium. Isometric ; often granular massive. Common as a microscopic ingredient of most phonolytes. Lake Laach, etc. \j Lapis-lazuli (Lasurstein, Germ.). — Not a homogeneous mineral according to Fischer and Vogelsang. The latter calls it " a mixture of granular calcite, ekebergite, and an isometric, ultramarine mineral, generally blue or violet. " Much used as an ornamental stone. J LEUOITE.* Tetragonal, according to v. Rath, c = 0*52637. Usual form as in f. 570, closely resembling a trapezohedron. Twins : twinning-plane 2-i ; ci-ystals often very complex, con- sisting of twinned lamellas, as indicated by the stria- tions on the planes. Often disseminated ingrains; rai'ely massive granular. II.=5-5-6. G. = 2-4:4-2-56. Lustre vitreous. Color wliite, ash-gray or smoke-gray. Streak nucolored. Translucent — opaque. Fracture conchoidal. Brittle. Optically uniaxial ; double i-efraction weak, negative (from Aquacctosa), positive (from Frascati). Comp. — Formula K..AlSi40i 2= Silica 55 0, alumina 23 "5, potash 21-5=100. Q. ratio for K : Al : Si=l : 3 : 8, for bases to silicon 1 : 3. Pyr., etc B.B. infusible ; with cobalt solution gives a blue color (alumina). Decomposed by hydrochloric acid without gelatinization. Diff,— Distinguished from analcite by its infusibility and greater hardness. Obs. — Leucite is confined to volcanic rocks, and is common in those of certain parts of Europe ; also found in those of the western United States. At Vesuvius and some other parts of Italy it is tl ickly disseminated through the lava in grains. It is a constituent m the nephehn-doieryte of Merches in the Vogelsberg ; abundant in trachyte between Lake Laach and Andernach, on the Rhine. The question as to whether the crystals of leucite belong to the isometric or the tetragonal ^stem has excited much discussion. Hirschwald (Tsch. Mm Mitth., 1875. 227) shows that while implanted crystals arc sometimes distinctly Utnigoiial, others, especially those which are imbedded, are as clearly isometric, while between the two there exist many transitioii cases. He claims that the mineral is in fact iiioiuet7-ic, but having a polysyminetric develop ment. there existing a wide variadon from the isometric type. The question cannot be con •idered as entirely decided. OXYO£N COMPOUNDS. — ANHYDROUS SLL10ATE8. 319 Feldsjpar Group.*^- The feldspars are characterized by specific j^ravity Lelow 2-85 ; Larducsa 6 to 7, fusibility 3 to 5 ; oblique or cliiioliedral crystallization ; prismatic angle near 120° ; two easy cleavages, one basal, the other brachydiagonal, inclined together either 90°, or very near 90° ; cleavage a prominent fea- ture of many massive kinds, and distnict in the grains of granular varieties, giving them angular forms ; close isomorphism, and a general resemblance in the systems of occurring crystalline forms ; transition from gi-anular varieties to compact, hornstone-like kinds, called felsites, which sometimes occur as rocks ; often opalescent, or having a play of colors as seen in a direction a little oblique to i-i ; often aveuturine, from the dissemination of microscopic crystals of foreign substances parallel for the most part to the phines O and /. The bases in the protoxide state are calcium, sodium, potassium, and in one species barimu ; the sesquioxide base is only aluminum ; the qnantivalent ratio of E. : R is constant, 1:3; while that of the silicon and bases varies from 1 : 1 to 3 : 1, the amount of silicon increasing with the increase of tho alkali metals, and becoming greatest when alkalies are the only protoxides. The included species are as follows : Crystallization. Approx. Q. ratio E,R,SL Anorthite Lime feldspar Triclinic 1:3:4 Labradokite Lime-soda feldspar "' 1:3:6 Hyalopiianb Baryta-potash feldspar MoDOclinic 1:3:8 And E SITE Soda-lime feldspar Triclinic 1:3:8 Oligoclase it n u " 1:3:9 Albite Soda feldspar (( 1 : 3 : 12 Orthoclase Potash feldspar Monoclinic 1 : 3 : 13 To the above list should be added, according to DesCloizeaux, the triclinic, potash feldspar, MICROCLINE, which has the composition of orthoclase. The above ratios are only approximate, for the analyses show a wide variation in the amount of silicon, and an exactly proportionate variation in the amount of aikali ; the two elements vary in most cases, as has been long recognized, according to a simiole law. There seems hence to be a gradual transition between the successive specie.!) ; but this is due, in part, to mixtures produced by contemporaneous crysiallizatiou (comi^are pei-thitc, p 326, and the description of microcUiie^ p. 32G). The unisilicate ratio of 1 : 1 for bases and silicon is found in anorthite only, as shown above. With Ca alone, as in this species, the Q. ratio for rVl and Si is 3 : 4 ; with Na2 alone, 3 : 13; and for kinds containing combinations of the two, exact combinations of these ratios, iii^3ki : n • • i.1. ..• o 4?/i+l2ft. 7iCa, giving the ratio 3 : m+n An explanation of the above fact, and of the variation in ratio shown by analyses, was offered by Hunt, and has since been developed by Tschermak. The existence of two distinct triclinic feldspars is assumed: anorthite Ca:\:lSijOB, and albite Na2iVlSi„0ic, and the other species (sometimes embraced under the general term plagioclase) are regarded as due to inoino)-- pho'Xb mixtures of these two members in uitlerent proportions. They have thin the general formula -j ;j,jfn lygj'Q" / For labradc .-ite the ratio oi m : n is mostly 3 : 3, also 3 : 1, etc.; for andesite the ratio of m : n varies about 1 : 3, and for oligoclase the ratio of w : n is 3 : 10, also 1 : 3, etc. In accordance with the above formula, if Ca : Na=6 : 1, then Al : 81= 1 : 2-30S; for Ca : Na=3 : 1, Al : Si=l : 1-257; for Ca : Na=l : 1, Al : Si=l : 3-33 ; foi Ca : Na=l : 3, Al : Si=:l : 44 ; for Ca : Na=i : 6, :il : Si=l : 5. Tliis method of viewing the feldspar species has the advantage of explaining the wide varia- tion in their composition, and is generally accepted among German mineralogists DesCloi- ' teaux regards his observations upon the optical characters of the feidsjiars (see p. 2'J8) aa showing that they are in fact distinct species, and not mde terminate isomorphous mixtiu"C8. 320 DESCRIPTIVE MINERALOGY. O^jticnl properties of the tricUnic feldspars. — The following table contains the nioie import- ant optical properties of the feldspar species as determined by DesCloizeaux (C. R., Feb. 8. 1875, and April 17, 187G). Bx=Bisectrix. Anoethite. Labbadoeite. Oligoclase. Albite. MiCROCLINJt. Acnte bisectrix always — Position of always -+- generally — sometimes -f always + always — Angle made by the+Bx. the Bx. has with a normal to i-i (g) no simple 30° 40' 18^ 10' 15° 15° 26' Same, with normal to relation to 0{p) the planes observed 56° 68" 78° 35' Angle made by the line in which the plane of on the crys- Line paralla the optic-axes cuts i-i, tals. to the edge with edge i-i/ 0(g' /p). 27°-28° 0\i-i. 20° 5° 6' Same, with edge i-i I iff' ni} 37°25'-3(r25' U (( 96° 28' (front) p < r(+Bx.) Ordinary dispersion. . . . p < «(-Bx.) p > t'(+Bx.) p < v{+Bx.) p < •p(+Bx.) Parallel or perpendicular Inclined. Crossed; also Crossed; also Inclined ; Horizontal to plane of polariza- slight in- slight 171- probably also (-Bx.) also tion. dined. clined. slight hori- zontal. inclined (+Bx.) Optic -axial angle (in air] for red rays. 84° 58' 88° 15' 8r 35' 80° 39' 87' 54' for blue rays 85' 59' 87^ 48' 88= 31' 81° 59' (Somma) (Labrador) (Sunstone, Tvedestrand) (Roc tourne; Amazonst'ne, Mursmsk. The axial divergence is quite constant for albite, labradorite, and anorthite, but varies for oligoclase even in different sections taken from the same specimen. Andesine (q. v.) is regarded by DesCloizeaux as an altered oligoclase. DesCloizeaux gives the following method of distinguishing between the feldspars by optical means : It is necessary to obtain a transparent plate parallel to the easiest cleavage ( 0). Such sections obtained from crystals or lamellar masses of aibite, oligoclase, labradorite, and the majority of those of mici'ocline, show hemitropic bauds, more or less close together, arranged along the plane parallel to the second cleavage (i-i) \ for orthoclase and microline in simple crystals., two sections placed in opposite positions serve to produce the same effect. These sections are thus brought between the crossed Nicols of a polarization-microscope. (1) For orthoclase the maximum extinction takes place when the two sections are parallel to their plane of contact ; the edge 0, i-i being in the plane of polarization of the micro- scope. (2) For microcline., the whole structure consists of a multitude of very fine parallel bands; the section may show microcliue alone, either hemitropic or not hemitropic, or microcline and orthoclase ; the extinction can take place at 30" 54' between the adjoining bands of the same plate of the made (microcline alone), at 30^ 54' between the typo plates of the made (micro- cline in bands), or at 15' 27' between the adjoining bands (microcline and orthoclase). In the last case the whole of two lamellifi of the made show at the same time an extinction oblique to the plane of composition, belonging to the microcline, and one parallel to this plane for the orthoclase. (3) For albite, the extinction between two bands takes place at an angle of 6° 32'. (4) For oUgodase, the extinction is simultaneous in the two bands, and when the plane of composition coincides with the plane of polarization of the polariscope, it shows that the structure is homogeneous. (5) For labradorite, the extinction takes place at 10° 24' between the alternate lines of the hemitropic lamellap.. It follows from this that a plane normal to the plane of the axes cuts the base along a line luaking with the edge Oji-l the following angles: 0° in orthoclase, 15° 27' in microcline, 3" It)' in albite, 5" 12 in labradorite. A variation of one ot two degrees from the above mean angles was observed in some ipeoimens. See further on p. 426. OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 321 Diff. — The feldspars are distinguished from other species by the charcacters already st-aiod prominent among which are : cleavage in two diiectione, nearly or quite at right angles ti each other ; also hardness, etc. The triclinic feldspars can in most cases be distinguished from orthoclase by the fine stria- tion due to repeated twinning. This striation can often be seen by the unaided eye upon the cleavage face {0), And its existence can always be surely tested by the examination of a thin y>Dtion in polarized light, the alternate bands of color showing the same fact. The separation of the different triclinic species can be surely made by complete analysis only, or at least by the determination of the amount of alkali present. The degree of fusi- bility, the color of the flame, and the effect produced by digestion in acids, are often import- ant aids. In the hands of a skilled observer the optical examination may give decisive results. v/ ANORTHITE. Indianite. c^\^ n,^A/-T -^^ <-' /A/' = 120° 110° yyvy^rs^ 31', O A t-?, Triclinic. c:h\d = 0-S6663 : 1 -57548 : 1 (over 2-i) = U° 10', O h I = 114° 6^', 6» A / 40', A 2-1 = 98° 46' ; a = 93° 13^', ^ = 115° 55^', y = 91° 11-^' Cleavage : O, i-i perfect, the latter least so. Twins similar to those of albite. Also mas- sive. Structure granular, or coarse lamellar. H.— 6-7. G. = 2-6t)-2-78. Lustre of cleavage planes inclining to pearly ; of other faces vitreous. Color white, grayish, reddish. Streak uncolored. Transparent — translucent. Fj'acture conchoidal. Brittle. Var. — Anorthite was described from the glassy crj-stals of Som- ma. LuUanite is a white, grayish, or reddish granular anorthite from India, first described in 1R02 by Count Boumon. Comp Q. ratio for R : Al : Si=l : 3 : 4. Formula CaAlSi,08=Silica 43-1, alumina 36-8, lime 20' 1 = 100. The alkalies are sometimes present in very small amounts. Pyr., etc. — B.B. fuses at 5 to a colorless glass. Decomposed by hydrochloric acid, with separation of gelatinous silica. Obs. — Occurs in some granites; occasionally in connection with gabbro and serpentina rocks ; in some cases along with corundum ; in many volcanic rocks. Found in the old lavaa in the ravines of Monte Somma ; Pesmeda-Alp, Tyrol ; in the Faroe islands ; in Iceland ; near Bogoslovsk in the Ural, etc. Bytownite has been shown by Zirkel to be a mixture. Bytown, Canada. V LABRADORITE. Triclinic. Ihl-l^V S7', 0^-1 = 93° 20', OaI =110° 50',O AT = 113° 34'; Marignac. Twins: similar to those of albite. Cleavage: O easy; ^-ilessso; /traces. Good crystals rare ; generally massive granular, and in grains cleavable ; sometimes cryptocryntalline or hornstone-like. H. = 6. G. = 2-67-2'76. Lustre of O pearly, passing into vitreous; elsewhere vitreous or snbresinous. Color gray, brown, or greenish, some- times colorless and glassy ; rarely porcelain-white ; usually a change of colors in cleavable varieties. Streak uncolored. Translucent — subtrans- lucent. Comp., Var.— Q. ratio for R : Al : Si=l : 3 : 6, but varying somewhat (see p. 819). Formula RAlSiado ; here R=Ca and Na^. The atomic ratio for Na : Ca.-2 : 3 generally, this corresponds to Silica 52-9. alumina 30"3, lime 123, soda 4'5=100. Var. 1. Cleavable. {a) WeU crystallized to (b) massive. Play of colors either wantir^f, m 322 DESCKIFrn^E MINEKALOGY. in some colorless crystals ; or pale ; or deep; blue and green are the predominant colors ; but yellow, nre-red, and pearl-gray also occur. By cutting very thin slices, parallel to i-K from the original labradorite. they are seen under the microscope to contain, besides striae, great numbers of minute scales, like the aventurine oligoclase. which are probably gi*thite or hema- tite. These scales produce an aventurine effect which is quite independent of the play of colors which arises from the interference of the rays of light reflected by innumerable inter- nal lamellts (i?f;/.vc/i). The various forms of mmeivi\s (micro^.i'i/cifcs, mio'ojy/iyUites, etc.) en- closed in the labradorite, and their relation to it in position, have been thoroughly investigated by Schrauf (Ber. Ak., Wien, Dec, 18G9). Pyr,, etc. — B.B. fuses at 3 to a colorless glass. Decomposed with difficulty hj hydrochloric acid generally leaving a portion of undecomposed mineral. Obs. — Labradorite is a constituent of some rocks, both metamorphic and igneous; e.g., diabase, doleryte, basalt, etc. The labradoritic metamoiiihic rocks are most common among the f ormationsi of the Archaean or pre-Silurian era. Such are part of those of British America, northern New York, Pennsylvania, Arkansas; those of Greenland, Norway, Fmland, Sweden, and probably of the Vosges. Being a feldspar containing comparatively little .silica, it occurs mainly in rocks which include little or no quartz (free silica). Kiew has furnished fine specimens ; also Labrador. It is met with in many places in Canada East. Occurs at Essex Co., N. Y. ; also in St. Lawrence, Warren, Scoharie, and Green Cos. In Pennsylvania, at Mineral Hill, Chester Co. ; in the Witchita Mts. , Arkansaa, etc. Labradorite was first brought from the Isle of Paul, on the coast of Labrador, by Mr. Wolfe, a Moravian missionary, about the year 1770, and was called by the early mineralogists Labra- dor stone (Lnbradortitein), and also chatoyant, opaline, or Labrador feldspar. Labradorite receives a fine polish, and owing to the chat 'yant reflections, the specimens are often highly beaiitiful. It is sometimes used in jewelry. Maskelynite. — Occurs in transparent, isometric, grains in the meteorite of Shergotty. Same composition as labradorite. ANDESITB. Andesine. Trielinic. Approximate ano^les from Esterel crystals (DcsCl.): OAi-ty left, S7°-8S', O A /= 111°-112°, OaT = 115°, lAi-i = 119°-12(P. P Ai-i =120°, OA2-l = 10r-l02°. Twins: resemb'lincr those of albite. Sel- dom ill crystals. Cleavage more uneven than in albite. Also granular massive. lI.=:5-6. G.=2-61-2*74:. Color white, gray, greenish, yellowish, flesh- red. Lustre subvitreous, inclining to pearly. Comp Q. ratio 1:3:8, but varying to 1 : 3 : 7. General formula RrVlSi40,; ; R=Na2 and Ca in the ratio 1 : 1 to 3 : 1 ; if the ratio is 1 : 1, the formula corresponds to Silica 59 "8, alu- mina 25-5, lime 7 0, soda 7 '7= 100. Pyr., etc. — Andesite fus-es in thin splinters before the blowpipe. Saccharite melts only on thin edges ; with borax forms a clear glass. Imperfectly soluble in acids. Obs. — Occurs in many rocks, especially some trachytes. The original locality was in the Andes, at Marmato ; also in the porphyry of I'Esterel. France ; in the Vosges Mts. ; at Vap- nefiord, Iceland, in honey-yeUov/ transparent crystals, etc. In North America, found at Chateau Richer, Canada, forming with hyper.sthene and ilmenite a wide-spread rock ; color flesh-red. Andesite is regarded by DesCloizeaux as an altered oligoclase, but many careful analyaet |H)int to a feldspar having the composition given abov^ HYALOPHANE, .Monoclinic, like orthoclase, and unifies nearly the same. 6^= 64° 16', CaI= 118° 41', OAl-i= 130° 55^'.^ Cleavage : O perfect, U somewhat less &o. In small crystals, single, or in groups of two or thi-ee. OXYGEN COMPOUNDS ANUYDROUS SILICATES. 323 H.— -6-6'5. G. = 2'80, transparent ; 2'905, translucent. Lustre vitreous Dr like tliat of adularia. Color white, or colorless ; also flesh-red. Trans- parent to ti'anslucent. Oomp.~Q. ratio for R : R : Si = l : 8 : 8. Formula (Ba,Ko)T^lSi,0,2. Analysis of hyalo- phane from the Binnenthal by StockarEscher, SiOj 52-67, AlOa 21 -13, MgO 004, CaO 0-46, BaO 15 0.3, Na,0 2-14, KoO 782, H,0 0-58 = 99 -88. Pyr., etc. — B.B. fuses with difficulty to a blebby glass. Unacted upon by acids. Obs. — Occurs in a granular dolomite near Imfeld, in the Biunenthal, Switzerland ; also ut Jakobsberffin Sweden. OLIGOOLASE. Triclinic. /A /' = 120° 42', O A i-l, ov. 2-1' = 93° 50', OaI= 110° 55', Oa T = 114° 40'. Cleava.i^e : 0, U perfect, the latter least so. Twins: similar to those of alhite. Also massive. II. = (>-7. G. = 2-56-2-72; mostly 2-65-2-69. Lustre viti'eo-pearly or waxy, to vitreons. Color usually whitish, with a faint tinge of grayish- green, grayish-white, reddish-white, gi'eenish, reddish ; sometimes aventiirine. Transparent, Buhtranslucent. Fracture conchoidal to uneven. Comp., Var.— Q. ratio for R : Al : Si = l : 3 : 9, though with some variations (see p. 297). Formula RAlSi»Ou. with R=Nan(Ko),Ca The ratio of 3 : 1 for Na : Ca corresponds in this formula to Silica 61*9, alumina 24'1, lime o'2. soda 8-8=100. Var. 1. Clearable ; in crystals or massive. 2. Coinptct massive ; oligodase-felsite ; includes part, at least, of the so-called compact feldspar orfelsite, consisting of the feldspar in a com- pact, either fine granular or flint-like state. 3. Aventurine oligoddse, or sunstone. Color grayish-white to reddish-gray, usually the latter, with internal yellowish or reddish fire-like refleitions proceeding from disseminated crystals of probably either hematite or gothite. 4. Moonstone pt. A whitish opalescence. Pyr., etc. — B.B. fuses at 35 to a clear or enamel-like glass. Not materially acted upon by. acids. Obs. — Occurs in porphyry, granite, syenite, serpentine, and also in different eruptive rocks. It is sometimes associated with orthoclase in granite, or other gTanit^-like rocks. Among its localities are Pargas in Finland ; Schaitansk, Ural ; in protogine of the Mer-de -Glace, in the Alps ; in fine crystals at Mt. Somma ; as sunstone at Tvedestrand, Norway ; in Iceland,, colorless, at Hafnefjord [Jutfnvfiordite). In the United States, at Unionville, Pa. ; also at Haddam, Ct. ; Mineral Hill, Delaware Co., Pa. ; at the emery mine, Chester, Mass. Named in 182(5 by Breithaupt from o'-iyar, little, and K'Anu, to cleave. TscHERMAKiTE (v. Kobell). — Supposed to be a magnesia-feldspar, but the conclusion was probably based on the analysis of impure material. Later investigations (Hawes, Pisani) make it an oligoclase. Occurs with kjerulfine from Bamle, Norway. ALBITE.* Triclinic. IaT - 120° 47', A i-l = 93° 36', OhI' - 114° 42', A I = 110° 50', 6> A 2-r = 136° 50', 6> A2-i = 133° 14'. Cleavage: O, i-\ perfect, the first most so; 14 sometimes distinct. Twins: twinning-plane i'-i, axis of revolution normal to i-l^ this is the most connnon method, a/id its repetition gives rise to the fine striations (p. 91) upon the plane O, which are so characteristic of the triclinic feldspars ; twinning-plane, %l (f. 578) 324 DESCRIPTITE Sn>'ERALOGT. analogous to the Baveno twins of orthoclase ; also twinning-axis, llie vertical axis (f. 575) ; twinniug-axis, the niaci-odiagonal axis* {h), the j)e7'idi?)e twins. Double twins not uncommon. True simple crystals very rare. Also mas- sive, either lamellar or granular ; the laminse sometimes divergent ; granulai varieties occasionally quite fine to impalpable. 578 579 Pericline. Middletown, Ct. H.=:6-7. G.=2-59-2-65. Lustre pearly upon a cleavage face ; vitre(^u3 in other directions. Color white, also occasionally bluish, gray, reddish, greenish, and green ; sometimes having a bluish opalescence or play of colors on 6^. Streak uncolored, Tran.sparent — subtranslucent. Fracture uneven. Brittle. Comp., Var.— Q. ratio Na : Al : Si=l : 3 : 12. Formula NaoAlSieOie^SilicaGS-G, alumina 19*6, sodall'8=100. A small part of the sodium is replaced usually, if not always, by potassium, and also by calcium (here Nao by Ca). But these diflEerences are not externally apparent. Var. 1. Ordinary, [a) In crystals or cleavable massive. The angles vary somewhat, especially for plane 7'. (b) Av entwine ; similar to aventurine oligoclase and orthoclase. (c) Moonstone ; similar to moonstone under oligoclase and orthoclase. Peristerite is a whitish adularia-like albite, slightly iridescent, having G. =2 ■(52(3 ; named from TrrpiGTepii, pigeon, the colors resembling somewhat those of the neck of a pigeon, (d) Pericline is in large, opaque, white crystals, short and broad, of the forms in f. 577 (f. 334, p. 101) ; from the chlorite schista of the Alps. Lamellar ; clearelandite, a white kind found at Chesterfield. Mass. Pyr., etc. — B.B. fuses at 4 to a colorless or white glass, imparting an intense yellow to the flame. Not acted upon by acids. Obs. — Albite is a constituent of several rocks, as dioryte, etc. It occurs with orthoclase in some granite. It is common also in gneiss, and sometimes in the crystalline schists. Veins of albitic granite are often repositories of the rarer granite minerals and of fine crystalliza- tions of gems, including beryl, tourmaline, allanite, columbite, etc. It occurs also in some ■"arachyte, in phonolyte, in granular limestone in disseminated crystals, as near Modane in Savoy. Some localities for crystals are : Schneeberg in Passeir, in simple crystals ; Col du Bonhomme ; St. Gothard, and elsewhere in the Alps ; Penig, etc. , Saxony ; Arendal ; Green- land ; Island of Elb*. In the U. S., in Maine, at Paris. In Mans., at Chesterfield; at Goshen. In Conn., at Haddam ; at Middletown. In iV. Tork, at Granville, Washington Co. ; at Moriah, Essex Co. In Penn., at Unionville, Delaware Co. The name Albite is Jerived from albus, white, in allusion to its color, and was given the ■pecies by Gahn and Berzelius in 1814. ^ * Vom Rath has recently shown this to be the- true method of twinninj hence that the explanation of Rose (given on p. 101) is incorrect. I this case, and OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 325 l/ ORTHOCLASE. Monoclinic. 6^= 63° 53', /a/= 118° 4S', Oa1-1 = 153° 28'; c:h: d = 0-814 : 1-51S3 : 1. Oa 1-i = 120° 41', Oa 2-i = 99° 38', O A 2 = 98° 4', Cleavage: 6^pei-fect; t'-l less distinct ; t-i faint; also imperfect in the direction of one of the faces /. Twins: tvvinning-plane, i-i {Curlshad twins) f. 582, but the clinopinacoid («-i) the composition-face (see p. 98) ; /a /= 169° 28' 587, each side of the prism then an (see also p. 99). Often massive, granular ; sometimes lamellar. Also compact cj-yp to-crystalline, and sometimes flint-like or jasper-like. 580 581 582 583 588 589 Loxoclase. II. = 6-6-5. G. = 2-44-2-62, mostly 2-5-2-6. Lustre vitreous; on cleav- age-surface sometimes pearlj'. Color white, gi'ay, flesh-red, common; greenish-white, bright-green. Streak nncolored. Transparent to trans- lucent. Fracture conchoidal to uneven. Optic-axial plane sometimes in the orthodiagonal section and sometimes in the clinodiagonal ; acute bisec- trix always negative, normal to the orthodiagonal. Comp., Var.— Q. ratio for K : Al : Si=l : 3 : 12. Formula KnAlSioO,«=Silica 64-7, alu- mina 18'4, potash 1()'9 = 10U; with sodium sometimes replacing part of the potassium. The orthoclase of Carlsbad contains rubidium. The varieties depend mainly on structure, varia- tions in angles, the presence of soda, and the presence of impurities. The amount of sodium detected by analyses varies gradtly, the \a,rietj sanidin (see below) sometimes containing 6 per cent. The variations in^wigles are large, and they occur some- times even in specimens of the same locality. Tl^ crystallization is normally monoclinic, and the variations are simply irregularities. There arc also large optical variations in ortho- clase, on which see DesCl. Min., i. , 329. Var. 1. Ordinnri/. In cry.stals, or cleavajJj^'massive. Adularia (adular). Transparent, oletvable, usually with pearly opalescent Mpictions, and sometimes with a play of colors like labradorite, though paler in shade. Mog^cone belongs in part here, the rest being albite and oligoclase.^&/«.sii of type I. , Vesuvius. In accordance with these facts DesCloizeaux has proposed that the thre" types be regarded as distinct species, with the names given above. I. HUMITE.* Including type I., Scacchi, Vesuvius. Also rare crystals from Brewster, N. Y. The latter large, coarse, and having sufiEered more or less alteration. Ortborhombic. Holobedral. i-2 {o^) A f 2 = 130° ID'; O [A) A 3-i (^^) := 102° 4S' ; 0^ l-l (f) = 124° 16'; 6> A 3-i (e^) = 103^ 47' ; 6» a 1- ■ (e^) = VMi" 21' ; Oa 1-5 (y3) = 121° 44'. Twins : twiniiiiig-plane ^-i, also f4, in burb cases tbe angle of tlie liorizontal prisin is nearly 120°. Optic-axial plane parallel to tbe base, acute bisectrix positive, normal to i-i. Dispersion almost zero. 2IIa = 7^" 18' -79° tor red rays. (DesCl.) Vesuvius. Brewster. Brewster, a. CHONDRODITE.* Including type II. of Scacchi, Vesuvius ; also crystals from Finland, Sweden, and with few exceptions those of Brewster, N. Y. Monoclinic. ^A^ = 122° 29'; J. A ^ = 109° 5'; AAe^' = 10S° 58'; A:n^= 103° 12' ; A A i^' = 103° 9' ; A A r^ = 135° 20' ; A A r^ = 125' 50^; C'A7-^ = 146°24'; 6Vx ^i^ = 135° 40' : C'Atz'' = 135° 41'. Tbe letters (tbose employed by Scaccbi) correspond to the following Bymbols •— A= O i = l-i e^ = — 2-^ n' = — 2 ^1 _ _4.^ ^3_ -f^ 24 n^' — 2 1^ = 4.6 ./ — 4-^ m: = -6-f. -i. Twins : twinning plane |-* (±?) and f-?! ( + ?), (both having a prismatic angle nearly 120°) ; also the basal plane (Brewster, K Y., f. 593). Optic-axial plane makes an angle of 26° with the base; acute bisectrix 328 DESCRIPTIVE MINERALOGY. positive, normal to the clinopinacoid {C). 2Ha=88'' 48' for rod rays, Brewster, K Y. (E. S. D.). 2Ha=86° 14-87° 20' (red rays), Sweden, (DesCl.) The above angles are those given by DesCloizeaux; the author's own measurements on the crystals from Brewster (not yet completed), point to a smaller variation from the rectangular type. DesCloizeaux makes the plane e^'=i-i, and i"*—!, r'^— 1, r^= —1. 693 A / /'/ e' \4\ 2 /»» Li n Xr^ /'"^ \ in ,>-^\ \ r4 r4 7-4 9 no: Brewster. Brewster. Vesuvius. Ill, CIiINOHUMITE. Including type III. of Scacchi, Vesuvius ; alfio rare finely polished red crystals from Brewster, N. Y. Monoclinic. J. A ^ = 133° 40' ; ^ A e^' = 133° 40' ; AN'i? — 125° 13' ; AKm = 114° 55' ; Ah m^ = 92° 58' ; A Nn = 132° 14' ; ^ A n"- = 122° 67'; ^A7i^ = 97°23';^An*' = 97° 23'; ^ Av^ = 131° 23 ;^Ar'' = ]25° 47' ; Ca r« =132° 5G' ; Cn r* = 137° 25'. DesCloizeanx. These letters (those employed by Seacehi) con-espond to the folloM-ing symbols : — A= O C = i-l i = |4 *2 = 1-^ 77. =z ^::^ -4 4 8_ 1 1 1 .5 r5 = = 3 ^ 8-5 e" = i- ?', 7^ = 7, and T* = -1, and ,.5 = 1. DesCloizeanx makes the plane e^' Twins: twiiniing-plane — ^i\ also the basal ]^lane (Brewster). Optic-axial plane makes an angle of 7^° Avith the base, Brewster (Dana) ; same angle toi- Vesuvian crystals eqnals 12° 28' (Klein), about 11° (DesCl.X Acnte bisectrix positive, normal to clinopinacoid. 2Ha=84° 40'-85° 15', vellow (Kl.).=84° 38'-85° 4' white crystals, and =86° 40'-87° 14' brown crystala (DesCl, ). Sections of crystals often shows a complex twinned strncture. In other physical and in chemictal characters these three snb-species are hai'dly to be distingnished. II. = 6-6-5, G. = 3*1 18-3-24, Lnstre vitreons — resinons. Color of crystals yellowish-white, citron-yellow, honey-yellow, hyacinth-red, broM nish (Vesuvius); also deep garnet-red (Brewster). Color of the mineial occur- ring niassive and in rounded imbedded grains (chondrodite at least in part) as of crystals, also sometimes olive-green, apple-green, gray, black. Streak white, or slightly yellowish, or grayifb. Transparent — subti-ansluceut Fracture subconchoidal — uneven. OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 329 Comp. — The chemical investigations of Rammelsberg and vom Rath have served to show a considerable variation in composition in the different varieties, but do not give decidedly different formulas to the three types of Scacchi, that is, the three minerals described above. In general Q. ratio for Mg : Si=i4 : 8 (IJ- : 1), and the formula then MgeSisOM ; or, as pre- ferred by Rammelsberg, Mg : Si = 5 : 4 (1^- : 1), and the formula is then Mg^SijOu. In all cases part of the magnesium is replaced by iron, and part of the oxygen by fluorine (F^), the amount varying from 2^ to 8} p. c, but certainly not dependent (v. Rath and Ramm.) upoa the three types. Analyses : — I. Humite, Vesuvius, II. Chondrodite, Vesuvius, II. Chondrodite, Brewster, II. Chondrodite, Sweden, III. Ciinohumite, Vesuvius, Chondrodite (?), N. Jersey, 33-97 SiO, FeO MgO F 35-63 5-12 54-45 2-43 33-26 2-30 57-92 5 04 34-10 7-28 53-72 4-14 33-96 6-83 53-51 4-24 36-82 5-48 54-92 2-40 33-97 3-48 56-97 7-44 CaO 0-23 AIO3 0-82=99-08, v. Rath. CaOO-74 AIO3 1-06=100-32, Ramm. AIO3 0-48=99-72, Hawes. AIO3 0-72=99 -26, V. Rath. AIO3 0-24=99 -86, V. Rath. =101-68, Ramm. Pyr., etc. — B. B. infusible ; some varieties blacken and then burn white. Fused with salt of phosphorus in the open tube gives a reaction for fluorine. With the fluxes a reaction fc iron. Gelatinizes with acids. Heated with sulphuric acid gives off silicon fluoride. Difif. — Distinguishing characters are : infusibility ; gelatinizing with acids ; fluorine reac- tion with sulphuric acid. Obs. — The localities of the crystallized minerals have already been mentioned. The granular chondrodite (?) occurs mostly in limestone. It is found in Finland and in Sweden ; at Taberg in Wermland ; at Boden in Saxony ; on Loch Ness in Scotland ; at Achmatovsk in the Ural, etc. Abundant in the counties of Sussex. N. J., and Orange, N. Y., where it is associated with spinel. In JV. Jersey, at Bryam ; at Sparta ; at Vernon, Lockwood, and Franklin. In iV. York, in Orange Co., in Warwick, Monroe, etc. ; near Edenville ; at the Tilly Foster Iron Mine, Bre-wster, Putnam Co. In Mass. , at Chelmsford. In Perm. , near Chadsford. In Canada, in limestone at St. Crosby; St. Jerome; St. Adele ; G-renville, etc., ibundou^ V TOURMALINE.* Turmalin, Germ. Rhombohedral. BAJi = 103°, OaB = 134^ 3' ; o = 0-89526. i^i- 599 600 603 Gouvemeur, N.Y. St. Lawrence Co., N.T. 154° 59', i A i = 133'' 8', i-2 A ^^ = 155° 14', i-2 A ^^ = 142*' 26'. Usualh 330 DESCRIFIIVE MENERALOGT. hemihedral, being often unlike at the opposite extremities, or heniiinorphic and the prisms often triangular. Cleavage : R^ —\. and ^-2, dithimlt. Sometimes massive compact; also columnar, coarse or fine, parallel or divergent. II. = 7-7'5. G. = 2-94:-3-3. Lustre vitreous. Color black, brownish- black, bluish-black, most common ; blue, green, red, and sometimes of rich shades ; rarely white or colorless ; some specimens red internally and green externally ; and others red at one extremity, and green, blue, or black at the other. Dichroic (p. 165). Streak uncolored. Transparent — opaque ; greater transparency across the prism than in the line of the axis. Frac- ture subconchoidal — uneven. Brittle. Pyroelectric (p. 169). Var.— 1. OrdirMvy. In crystals, [a] RubelHte ; the red sometimes transparent, (b) Indi- eolite ; the blue, either pale or bluish-black ; named from the indigo-blue color, (c) Brazilian Sapphire \\n jewelry] ; Berlin-blue and transparent; (fi) BrasHian Emerald, Chrysolite {oz Peridot) of Brazil ; green and transjjarent. (e) Peridot of Ctylon ; honey -yellow. (/) Ach- roite ; colorless tourmaline, from Elba, {(j) Aphrizite ; black tourmaline, from Krageroe, Norway. (Zi) Columnar und black ; coarse columnar. Resembles somewhat ho nblende, but nas a more resinous fracture, and is without distinct cleavage or anything like a fibrous appearance in the texture. Comp. — Q. ratio of all varieties for II : Si=3 : 2 (Rammelsberg), consequently the general II I i ;i formula is Il£(R,;,fi)Si05. R may represent here H, K, Na, Li ; also R=Mg(Ca).Fe,Mn, and R=3tl,B2 ; further thau this the Si is often in part rejilaced by Fj. Rammelsberg distin- guishes two groups, where the Q. ratio for B : i^l : Si=iJ : G : 8, and (2) with the Q. ratio for B : Al : Si = l : 3 : 8. In the first group fall most of the yellow, brown, and black varieties, II I the bivalent elements (Mg,Fe) predominating, the general formula being R3(Rc)RaSi40;o. The second group includes the colorless, red, and slightly green kinds, the univalent elementa I II appearing most prominent, especially lithium. The general formula is Rc(R:;)ftfSia046. Several distinct varieties are made under these groups, which wUl be sufliciently illustrated by the following analyses, by Rammelsberg. I. Gouverneur, brown-; G. =o*0-;9. II. Haddam, black; G.=313G. III. Goshen, bluish-black; G.=3-203. IV. Paris, Me., red; G.=3-U19. V. Chesterfield, Mass., green; G.=3-069. SiOi B..O3 AIO3 FeO MnO MgO CaO Na.,0 K.O Li,0 F H,0 I. 38-85 (8-35) 31-32 1-14 14 89 1-60 1-28 0-26 2-3U r 100 -00 II. 37 oO (9-02) 30-87 8-54 8-60 1-33 1-60 73 1-81 = = 100-00 III. 3G-22 10-65 33-35 11-95 1-25 0-63 1-75 0-40 0-84 0-82 2-21 = = 100-82 IV. 38-19 9-97 42-63 1-94 0-39 0-45 2-60 0-68 1-17 1-18 2 00= = 100-20 V. 38-46 9-73 36-80 6-38 0-78 1-88 2-47 0-47 0-72 0-55 2-31 = = 100-55 Fyr., etc. — I. fuse rather easily to a white blebby glass or slag ; II. fuse with a strong heat to a blebby slag or enamel ; III. fuse with diflScult\ , or, in some, only on the edges ; IV. fuse on the edges, and often with great difficulty, and some are infusible ; V. infusible, but becom- ing white or paler. With the fluxes many varieties give reactions for iron and manganese. Fused with a mixture of potassium bisulphate and tluorite gives a strong reac'^ion for boracic acid. By heat alone tourmaline loses weight from the evolution of silicon fluoride and per- haps also boron fluoride ; and only after previous ignition is the mineral completely decom- posed by fluohydvic acid. Not decomposed by acids (llamm. ). After fusion perfectly decom- posed by sulphuric acid (v. Kobell). Diff. — Distinguished by its form, occurring commonly in three sided, or six-sided prisms; absence of cleavage (unlike hornblende). It is less easily fusible than garnet or vesuvianite. B. B. (see above) gives a green flame (boron). Obs. — Tourmaline is usually found in granite, gneiss, syenite, mica, chloritic or talcose schist, dolomite, granular limestone, and sometimes in saudstoi;e near dykes of igneous rocks. The variety in granular limestone or dolomite is commonly brown. Prominent localities are Katherinenburg iu Siberia ; Elba ; Windisch Kappell in Carinthia ; ttozena ; Airolo, Switzerland ; St. Gothard. In Great Britain. Bovey Tracey in Devon : Cornwall, at different localities ; Aberdeen in Scotland, etc. In the U. States, in Maine, at Paris and Hebron. ■ In Mass., at Chesterfield ; at Goshen, bjuc. In iV. Hamp., Grafton ; Acworth, etc. In Couu.. at Monroe and Haddam, black. In JV. Vork^ OXYGEN COMPOUNDS — ANHYDROUS SILICATES. 331 QcarGouvemeur; near Port Henry, Essex Co., enclosing orthoclase (see p. 109); Pierrepont; near Edenville. In Penn. , near Unionville; at Chester; Middletown, and elsewhere. la Cnnndd, at G. Calumet Id. ; at Fitzroy, C. W, ; at Hunterstown, C. E. ; at Bathurst and Klmsley, C. W. GEHliENiTE. — Tetragonal. Color grayish-green. Q. ratio for R : R : Si=3 : 3 : 4, or 3 : 2 for bases and silicon. Formula CasRSi-.Oio, with K=:^l : Fe=5 : 1 ; this requires SUica 29-9, alumina 21-5, iron sesquioxide 6-6. lime i '20 = 100. Mt. Monzoni, Fassathal, Tyrol. K/ ANDALUSITE. Orthorhorabic. /A /= 90° 48', O A l-l = 144° 32' ; : 1*01405 : 1. Cleavage : / perfect in crystals from Brazil; i-l less perfect; i-l in traces. Massive, im- perfectly columnar, sometimes radiated, and grannlar. II. = 7*5 ; in some opaque kinds 3-6. G. = 3"05- 3-35, mostly 3-1-3-2. Lustre vitreous ; often weak. Color whitish, rose-red, flesh-red, violet, pearl-gray, reddish-brown, olive-green. Streak nncolored. Trans- parent to opaque, nsually snbtranslucent. Fracture uneven, subconclioidal. Var. — 1. Ordinary. H. =--7*5 on the basal face, if not elsewhere. 2. Chiastolite (made), Sterling. Mass. Stout crystals having the axis and angles of a different color from the rest, owing to a regu- lar arrangement of impurities through the interior, and hence ex- hiLiiing a colored cross, or a tesselated appearance in a transverse section. n.=3-7'5, varying much with the degree of impurity. The following figure shows sections of some crystals (,see also p. 110). c\l\d^ 0-71241 604 Comp.— Q. ratio for ft : Si=3 : 2 ; AlSi05=Silica 36 9, alumina 631 = 100. Sometimes a little FeOa is present. Pyr., etc. — B.B. infusible. With cobalt solution gives a blue color. Not decomposed by acids. Decomposed on fusion with caustic alkalies and alkaline carbonates. Diflf. — Distinguishing characters: infusibdity ; hardness; and the form, being nearly that of a square prism, unlike staurolite. Obs. — Most common in argillaceous schist, or other schists imperfectly crystalline ; also in gneiss, mica schist, and related rocks. Found in Spain, in Andalusia, and thence the name of the species ; in the Tyrol. Lisens vaUey ; in Saxony, at Briiun.sdorf, and elsewhere. In Ireland. In Brazil, province of Minas Geraes (transparent). Common in crystalline rocks of New England and Canada; good crystals have been obtained in Delaware Co., Perm., etc.' also in California; in Mass., at Sterling {chiastolite). i FIBROLITE. Bucholzite. Sillimanite. Orthorliouibic. /a/=96° to9S° in the smoothest crystals ; nsually largei, the faces /striated, and passing into i-^. Cleavage : i-l very perfect, bril- liant. Ci-vstals (;omm<)nlv lono; and slender. Also iibrous or columnai niHssne, sonietmies radiatmor. 332 DESCRIPTIVE MINERALOGY. II. = 6-T. G.=3*2-3'3. Lustre vitreous, approaching siibadainantiije Color liair-browii, gra^'isli-browii, grayish-wliite, grayish-green, pale olive- green. Streak uncolored. Transparent to translucent. Var. — 1. Sillimanite In long, slender crystals, passing into fibrous, with the fibres separ* able. 2. FibroUte. Fibrous or fi.ne columnar, firm and compact, sometimes radiated ; gray« ish-white to pale brown, and pale olive-green or greenish- gray. Bucholzite and monrolite are here included ; the latter is radiated columnar, and of the greenish color mentioned. Comp. — lUiSiOs, as for andalusite= Silica ^JGO, alumina 01) 1 = 100. Pyr., etc.— Same as given under andalusite. Di£f. — Distinguished from tremolite by its infusibility ; also by its brilliant diagonal cleav- age, in which and in its specific gravity it differs from cyanite. Obs. — Occurs in gneiss, mica schist, and related metamorphic rocks. In the Fassathal, Tyrol (bucholzite) ; at Bodenmais in Bavaria, etc. In the United States, at Worcester, Mass. Near Norwich, Conn. ; at Chester, near Saybrook {ifiUinmnite). In N. York, in Monroe, Orange Co. (monroUte). In Penn., at Chester on the Delaware; in Delaware Co., etc. In Delaware, at Brandy wine Springs. In N. Carolina, with corundum. Fibrolite was much used for stone implements in western Europe in the " Stone age." WoRTiiiTE, a hydrous fibrolite ; Westakite (Sweden) is related in composition. CTANITB.* Kyanite. Disthene. Triclinic. In flattened prisms ; rarely observed. Crystals oblong, usually very long and blade like. Cleavage : ^-^ distinct ; i-i less so ; O imperfect. Also coarsely bladed columnar to subfibrous. 11.:= 5-7*25, the least on the lateral planes. G. = 3-45-3-7. Lustre vit- reous — pearly. Color blue, white, blue al(>ng the centre of the blades or crystals with white margins ; also gray, green, black. Streak uncolored. Transl ucent — transparen t. Var. — The white cyanite is sometimes called Rhoetizite. Comp. — AlSi05=Silica 369, alumina 6o"l = 100, like andalusite and fibrolite. Pyr., etc. — Same as for andalusite. Diff. — Unlike the amphibole group of minerals in its infusibility ; occurrence in thin-bladed prisms characteristic. Obs. — Occurs principally in gneiss and mica slate. Found at St. Gothard in Switzerland ; at Greiner and Pfitsch in the Tyrol; also in Styria ; Carinthia ; Bohemia. In. Mass., aX Chesterfield, etc. In (7o?i;z., at Litchfield; at Oxford. In FcJV/w/i^, at Thetf ord. In Penn.^ in Chester Co. ; and Delaware Co. In N. Carolina. TOPAZ. » Orthorhombic. /A / = 124° 17', 6> A l-^ = 138° 3' ; c:l'. a =0-90243 : 1-8920 : 1 0M = 134° 25', 1 A 1, macr., = 141° 0'. Crystals usually hemihedra., the extremities being unlike; habit prismatic. Cleavage: basal, highly perfect. Also firm columnar ; also granular, coarse or fine. H. = 8. G. = 3-4-3-65. Lustre vitreous. Color straw-yellow, Mdne- yellow, white, grayish, greenish, bluish, reddish ; pale. Streak uncolored Transparent — ^subtranslucent. Fracture subconchoidal, uneven. Pyro- OXYGEN COMPOmsroS — ANHTDEOTJS SILICATES. 333 electric. Optic-axial plane i-l ; divergence very variable, sometimes differ- ing much in different parts of the same crystal ; bisectrix positive, norraa^ to O. 605 5? 606 609 607 \ I 12 u 608 tn w Trumbull, Ct. Schneckensteln. 0=1 :5= Oomp. — AlSiOs, with part of the oxygen replaced by fluorine (F;) ; ratio of Fo Silicon 15-17, aluminum 29-58, oxygen 34-67, fluorine 20-58=100. Pyr., etc. — B.B. infusible. Some varieties take a wine-yellow or pink tinge when heated. Fused in the open tube with salt of phosphorus gives the reaction for fluorine. With cobalt solution the pulverized mineral gives a fine blue on heating. Only partially attacked by sul- phuric acid. Diff. — Distinguishing characters: — hardness, greater than that of quartz; inf usibility ; perfect basal cleavage. B.B. yields fluorine. Ob3. — Topaz occurs in gneiss or granite, -with tourmaline, mica, and beryl, occasionally with apatite, fluorite, and tin ore ; also in talcose rock, as in Brazil, with euclase, etc., or in mica slate. Fine topazes come from the Urals ; Kamschatka ; Brazil ; in Cairngorm, Aberdeenshire ; at the tin mines of Bohemia and Saxony. Physnlite (a coarse variety), occurs at Fossum, Norway ; also in Durango, Mexico ; at La Paz, province of Guanaxuato. In the United States, in Conn., at Trumbull. In N. Car., at Crowder's Mountain. In Utah., in Thomas's Mts. ; from gold washings of Oregon. EUCLASE.* d-^yiy*.^^i Monocliuic. C - 79° 44'= A ^-^, /A /= 115° 0', 6> A 14 = 146° 45' ; c:l:d = 1-02943 : 1-5446 : 1 = 1 : 1-50043 : 0-97135. Cleavage : i-\ very perfect and brilliant ; 0, i-i mnch less distinct. Found only in crystals. H. = 7*5. G. t=3-09S (Ilaid.). Lnstre vitreous, some- what pearly on the cleavage-face. Colorless, pale moun- tain-green, ])assing into blue and white. Streak nn- colored. Transparent; occasionally subtransparent. Fractui-e conchoiclal. Very brittle. Comp.— Q. ratio for H : Be : r»tl : Si=l : 2 : 3 : 4, forR : Si=3 : 2 (H,=R, and 3R=A1), formula, H,Be,AlSi20,o=Silica 41*20, alumina 85-22, glucina 1739, water 6 19=100. Pyr., etc. — In the closed tube, when strongly Ignited, B.B. gives off water (Damour). B.B. in the forceps cracks and whitens, throws out points, and fuses at 5 5 to a white enamel. Not acted on by acids. Obs. — Occurs in Brazil, at Villa Rica ; in southern Ural, near the river Sanarka. 334 DESCRIPTIVE MINERALOGY. DATOLITE. Humboldtite. Monoclinic. C= 89° 54'= O (below) A i-i, /A /= 115° 3', 6> A 14 = 162° 27'; c : J :« = 0-49695 : 1-5712 : 1. 6>A -2-^ = 135° 13', 6>Al = 149° 33', /A /front = 115<^ 3', 24 A 24, ov. O, = 115° 21', i-^ A i-li, ov. i-i, — 76" 18', 44 A 44, ov. 6>, = 76° 88. Cleavage : 6> distinct. Also botry- oidal and globular, having a columnar structure ; also divergent and radi- ating ; also massive, granular to compact. Bergen Hill, Bergen Hill. ArendaL H.==:5-5-5.^ G.=2-8-3; 2-989, Arendal, Haidinger. Lustre vitreous, rarely subresinous on a surface of fracture ; color white ; sometimes gray- ish, pale-green, yellow, red, or amethystine, rarely dirty olive-green or honey-yellow. Streak white. Translucent; rarely opaque white. Frac- ttire uneven, subconchoidal. Brittle. Plane of optic-axes i-\\ nngle of divergence very obtuse ; bisectrix makes an angle of 4° with a nonuMl to i-v Var. — 1. Ordinary. In crystals, glassy in aspect. Usual forms as in figures. 2 CmnfoA OXYWEN COMPOUNDS — ANHTDEOTTS SILICATES. 335 massive. White opaque, breaking with the surface of porcelain or Wedg-ewood waie. From the L. Superior region. 3. Botryoidal ; BotryoUte. Radiated columnar, having a botrjoidal surface, and containing- more water than the crystals. The original locality of both the crys- tallized and botryoidal was Arendal, Norway. Haytorite is datolite altered to chalcedony, from the Haytor Iron Mine, England. Comp — Q. ratio for H : Ca : B : Si=l : 2 : 3 : 4, lilce euclase: formula HjCa2BjSiaOio= Silica 37-5, boron trioxide 2l"fl, lime35 0, water5'G = 100. Botryolite contains 10 (54 p. c. water. Pyr., etc. — In tlie closed tube gives off much water. B.B. fuses at 2 with intumescence to a clear glass, coloring the flame bright green. Gelatinizes with hydrochloric acid. Diff. — Distinguishing characters: glassy lustre; usually complex crystallization; B.B. fuses easily with a green flame ; gelatinizes with acids. Obs. — Datolite is found in trappean rocks ; also in gneiss, dioryte, and serpentine ; in me- tallic veins ; sometimes also in beds of iron ore. Found in Scotland ; at Arendal ; at Andreas- berg ; at Baveno near Lago Maggiore ; at the Seisser Alp, Tyrol ; at Toggiana in Modena, in serpentine. In good specimens at Roaring Brook, near New Haven ; also at many other localities in the trap rocks of Connecticut ; in N. Jersey, at Bergen Hill ; in the Lake Superior region, and on Isle Royale. San Carlos, Inyo Co., Cal., with garnet and vesuvianite. J TITANITE.* Sphene. MonocHnie. C = 60° 17' = 6> A i-i ; IM = 113° 31', M-l = 159" 39'; c : b : d =^ 0*56586 : 1*3251 : 1. Cleavage: I sometimes nearly per- fect ; i-i and —1 much less so ; rarely (in greenovite) 2 easy, —2 less so ; sometimes hemimoi-pliic. Twins : tv/inning-plane i-i ; iisnally producing thin tables with a reentering angle along one side ; sometimes elongated, as in f. 623. Sometimes massive, compact ; rarely lamellar. Ledbrite. Spintliere. SchWatiensteln. lI. = 5-5-5. G.=3"4:-3*56. Lustre adamantine — resinous. Coloi brown, gray, yellow, green, and black. Streak white, slightly reddish in greenovite 336 DESCRIPTIVE MINERALOGY. Transparent — opaque. J3rittle. Optic-axial plane i-t ; bisectrix positive Tery closely normal to 1-i (x) ; double i-efraction strong ; ax'al divergence 53''-5C° for the red rays, 46''-45» for the blue ; DesCl. Oomp., Var.— Q. ratio for Ca : Ti : Si=l : 2 : 2, or making the Ti basic (Ti=2R), R : Si s=3 : 2 ; formula (eqmvalent to RSiOe) CaTiSiOi = Silica 30-61, titanic oxide 40-82, lime 28 -5? =100. Var. — Ordinary, {a) Titanite ; brown to black, the original being thus colored, also opaque or subtranslucent. (b) Sp/iene {named fvom (T7, alumina 5192, iron protoxide 13 0(5, magnesia 2o3. water 1 ■52 = 100. The iron was first taken as FeOa, but JNIitscherlich showed that it was really FeO. Staurolita often includes impurities, especially free quartz, as first shown by Lechaitier, and since then by Fischer, Lasaulx, and Rammelsberg. This is the cause of the variation in the amount of BUica appearing in most analyses, there being^ sometimes as much as 50 p. c. Pyr., etc. — B.B. infusible, excepting the manganesian variety, which fuses easily to a black magnetic glass. With the fluxes gives reactions for iron, and sometimes for manganese. Imperfectly decomposed by sulphuric acid. Diff. — Always in crystals ; the prisms obtuse, having an angle of 129^. Obs. — Usually found in mica schist, argillaceous schist, and gneiss ; often associated with garnet, cyauite, and tourmaline. Occurs witi cyanite vnparagonite schist, at Mt Campione, Switzerland ; at the Greiner niountain. and elsewhere in the Tyrol ; in Brittany ; in Ireland. Abundant thioughout the mica slate of New England. In Maine, at Windham, and elsewhere. In Mass., at Chesterfield, etc. In Peiin. In Georgia, at Canton ; and in Fannin Co. SCHORLOMiTE. — Q. ratio for Ca+Fe + Ti : Si=2 : 1, nearly. Analysis by Ramm., Arkan- sas, SiOs 2G-09, TiOg 21 ol, FeOa 20-11, FeO 1-57, CaO 29-38, MgO 1-3(3=99-85. Color black. Fracture conchoidaL Magnet Cove, Arkansas ; Kaiserstuhlgebii-ge in Breisgau. HYDROUS SILICATES. L General Section. A. Biselicates. V PECTOLITE. Mouoclinic, isomorphous with wollastonite. Greg. Cleavage : i-i (orthoa.) perfect. Twins : twinning-plane i-i. Usually in close aggregations of aci- cular crystals. Fibrous massive, radiated to stellate. H.=5. G. = 2-68-2-78. Liretre of the surface of fracture silky or sub- vitreous. Color whitish or grayish. Subtranslucent to opaque. Tough. For Bergen mineral optic-axial plaue parallel to orthodiagonal, and very nearly normal to i-i\ acute bisectrix positive, parallel to orthodiagonal, and obtuse bisectrix nearly normal to cleavage plane or i-i ; axial angle in oil, through cleavage-plates, 143''-145° ; DesCl. Var. — Almost always columnar or fibrous, and divergent, the fibres often 2 or 3 inches long, and sometimes, as in Ayrshire, Scotland, a yard. Resembles in aspect fibrous varieties ol Datrolite, okenite. thomsonite, tiremolite, and woUastonite. 338 DESCRIPTIVE MINERALOGY. Comp.— Q. ratio for H : Na : Ca : Si=l : 1 ; 4 : 12, and for R : Si (where R includos Ca, tinu no,Na2) = l : 2, like wollastonite ; hence formula HNaCa.2Si30d = SLlica 54'2, lime 38"8, soda 9 3, water 2 •7=1 00. If the H does not belong with the bases, then the formula may be (Ramm.) NaoCaiSicOn + aq. Pyr., etc. — In the closed tube yields water. B.B. fuses at 2 to a white enamel Gela tinizes with hydrochloric acid. Often gives out a light when broken in the dark. Obs. — Occurs mostly in trap and related rocks, in cavities or seams ; occasionally in meta- morphic rocks Found in Scotland, near Edinburgh; in Ayr.shire; and at Taliver, etc., I. Skye ; at Mt. Baldo and Mt. JMonzoni in the Tyrol ; in Wermland ; at Bergen Hill, N. J. ; compact at Isle lloyale, L. Superior. Monoclinic. \J LAUMONTITE, Caporcianite. C=68°40', /A/=86°16', (9 A 1-i = 151° 9' ; c\h:d = 0"516 : 0*8727 : 1. Prism with very oblique terminal plane 2-^, the most common form. Cleavage : i-i and /perfect; ^-^ imperfect. Twins: twinning-plane ^-^. Also columnar, radiating or divei-gent. H.=3-5-4. G.=:2-25-2-36. Lustre vitreous, inclining to peai'ly upon the faces of cleavage. Color white, passing into yellow or gray, sometimes red. Streak uncolored. Transparent — translucent ; becoming opaque and usually pulverulent on exposure. Fracture scai-cely observable, uneven. Not very biittle. Double refraction weak ; optic- axial plane i-%; divergence 52° 24' for the red rays; bisec- trix negative, making an angle of 20° to 25° with a normal to i-i ; r)esCl. Comp.— Q. ratio for R : R : Si : H-1 : 3 : 8 : 4 ; and R : Si=l : 2 (8R=R). R=Ca, R =A1, and the formula is hence CaAlSi40i2+4aq= Silica 50 0, alumina 21 "8, lime 11 "9, water 16-3=100. Pyr., etc. — Loses part of its water over sulphuric acid, but a red heat is needed to drive off all. B.B. swells up and fuses at 2'7-3 to a white enamel. Gelatinizes with hydrochloric acid. Obs. — Laumontite occurs in the cavities of trap or amygdaloid ; also in porphyry and sye nite, and occasionally in veins traversing clay slate with calcite. Its principal localities are at the Faroe Islands ; Disko in Greenland ; in Bohemia, at Eule ; St. Gothard in Switzer- land ; the Fassathal ; the Kilpatrick hills, near Glasgow. Nova Scotia affords line specimens ; also Lake Superior, in the copper region, and on I. Royale ; also Bergen Hill. N. J. Okknite. — Formula H.CaSi-jOe + aq. having half the water basic = Silica 50 "(J, lime 26*4, water 17-0=100. Commonly fibrous. Color white, Faroe Is.; Disco, Greenland; Iceland. Gyuolite. — Occurs in radiated concretions at the Isle of Skye ; Nova Scotia. Formula perhaps HjCa^SisOu + aq. Centrallassite. Related to okenite, but contains 1 molecule more water. In trap of Nova Scotia. OHRYSOCOLLA.* Kieselkupfer, Genn. Cryptocrystalline ; often ojial-like or enamel-like in texture; earthy. Incrusting, or filling seams. Sometimes botryoidal. H.. = 2-4:. G. = 2-2-238. Lustre vitreous, shining, earthy. Color moun- tain-green, bluish-green, passing into sky-blue and turquois-blue ; brown to black when impure. Streak, when pure, white. Translucent — opaque. Fracture conchoidal. Rather sectile ; translucent varieties brittle. OXYGEN COMl'ODiJDS — HYDROUS SILICATES. 339 Comp. — Compofdtion varies much through impurities, as with other amori3hous substances, resulting from alteration. As the silica has been derived from the decomposition of othei silicates, it is natural that an excess should appear in many analyses. True chrysocolla cor- responds to the Q ratio for Cu : Si : H, 1:2: 2=CuSi034-2aq= Silica 34-2, copper oxide 45-8, watT 20 5 = 100. But some analyses afford 1:2:3, and 1:2:4. Impure chrysocolla may contain, besides free silica, various other impurities, the color varying from bluish-green 'to brown and black, the last especially when manganese or copper is present. Pyr., etc. — In the closed tube blackens and yields water. B.B. decrepitates, colors the flame emerald-green, but is infusible. With the fluxes gives the reactions for copper. With soda and charcoal a globule of metallic copper. Decomposed by acids without gelatinization. Diflf — Color more bluish-green than that of malachite, and it does not effervesce with acids. Obs. — Accompanies other copper ores, occurring especially in the upper part of veins. Found in most copper mines in Cornwall ; at Libethen in Hungary ; at Falkenstein and Schwatz in the Tyrol ; in Siberia ; the Bannat ; Thuringia ; Schneeberg, Saxony ; Kupfer- berg, Bavaria; South Australia ; Chili, etc. In Somerville and Schuyler's mines, New Jersey; at Morgantown, Pa. ; at Cornwall, Lebanon Co. ; JSova Scotia, at the Basin of Mines; also in Wisconsin and Michigan. Demidopfite ; CvANOCnALCiTK ; Resanite ; near chrysocolla. Catapleiite.— Analysis (Ramm.), SiO.> 39 78, ZrO^ 40-12, CaO 3-45, Na^O 7-59, RiOQUA =100 "18. Hexagonal. Color yellowish-brown, Lamoe, near Brevig, Norway. / B. UNISILICATES. CALAMINE. Galmei ; Kieselzinkerz, Oerm. Ofthorhorabic ; hemiinorpliic-heinihedral. /aZ=104:° 13', Oa1-1 = 148° 31', Daubar; c : 3 : « = 6124 : 1-2850 : 1. Cleav- age: /, perfect; O, in traces. Also stalactitic, inainmil- lated, botryoidal, and fibrous forms; also massive and granular. H. = 4-5-5, the latter when crystallized. G. = 3-lG-3-9. Lustre vitreous, suhpearly, sometimes adamantine. Color white ; sometimes with a delicate bluish or L'reenish siiade ; also yellowish to brown. Streak white. Transparerit — translucent. Fracture uneven. Brittle. Pyroelectric. Comp.— Q. ratio for R : Si : H=l : 1 : ^ ; Zn^SiOi-i-aq^ Silica 25 0, zinc oxide (J7'5, water 75 = 100. Pyr., etc. — In the closed tube decrepitates, whitens, and gives ofF water. B.B. almost infusible (F. = ()>; moistened with cobalt solution gives a green color when heated. On charcoal with soda gives a coating which is yellow while hot, and white on cooling. Moistened with cobalt solution, and heated in O.F., this coating assumes a bright green color. Gelatinizes with acids even when previously ignited. Decom- posed by acetic acid with gelatinization. Soluble in a strong solution of caustic potash. Diff. — D'stinguishing characters: gelatinizing with acids; infusibility ; reaction for zinc. Obs. — Calamine and smithsonite are usually found associated in veins or beds in stratified calcareous rocks accompanying blende, ores of iron, and lead, as at Aix la Chapelle; Bleiberg in Cariuthia ; Retzbanya ; Schemnitz. At Roughten Gill in Cumberland ; at Alston Moor ; near Matlock in Derbyshire ; at Castleton ; Leadhills, Scotland. In the United States occurs with smithsonite in Jefferson county, Missouri. At Stirling Hill, N. J. In Pennsylvania, at the Perkiomen and Phenixville lead mines; at Bethlehem; at Friedensville. Abundant in Virginia, at Austin's mines. 340 DESCRIPflVE MINERALOGY / PREHNITE. Orthorhombic. / A /= 99° 56', 6> A 1-i = 146^ llj' ; h\l\a= 0-669(53 : 1'19035 : 1. Cleavage : basal, distinct. Tabular crystals often united bj O^ making broken forms, often barrel-shaped. Usually reniforin, globular, and stalactitic with a crystalline surface. Sti-ucture imperfectly columnar or lamellar, strongly coherent ; also compact gi-anular or impalpable. II. = 6-6"5. G. = 2-8-2-953. Lustre vitreous; O weak pearly. Color light green, oil-green, passing into white and gray ; often fading on expo- sure. Subtransparent — translucent ; streak uncolored. Fracture uneven. Somewhat brittle. Comp. — Q. ratio for R:ft:Si:H=2:3:G:l, whence, if the water is basic, for bases and silicon, 1:1; formula HoCa^TtlSiaOio or Ca5AlSi30ii+aq= Silica 43'6, alumina 24-9, lime 27-1, water 4-4=100. Pyr., etc. — In the closed tube yields water. B. B. fuses at 2 with intumescence to a blebby enamel-like glass. Decomposed by hydrochloric acid without gelatinizing. Coupholite, which often contains dust or vegetable matter, blackens and emits a burnt odor. Diff. — B. B. fuses readily, unlike beryl and chalcedony. Its hardness is greater than that of the zeolites. Obs. — Occurs in granite, gneiss, syenite, dioryte, and trappean rocks especially the last. At Bourg d'Oisans in Isere ; in the Fassathal, Tyrol ; Ala in Piedmont ; Joachimsthal in Bohemia ; near Andreasberg ; Arendal, Norway ; jEdcIfors in Sweden ; in Dumbartonshire ; in Renfrewshire. In the United States, in Connecticut ; Bergen Hill, N. J. ; on north shore of Lake Superior ; , in large veins in the Lake Superior copper region. "^ Chlorastrolite and Zonochlorite from Lake Superior are mixtures, as shown by Hawes. ViLLARSiTE. — Probably an altered chrysolite. Formula RiSi04-t-iaq (or i^aq) R=Mg : Fe = 11 : 1. Traversella. V Cerite, Sweden, and Tritomite, Norway, contain cerium, lanthanum, and didymium. Thorite and Orangite contain thorium Norway. Paratiiorite. — In minute orthorhombic crystals, imb^ded in danburite at Danbury, Ct. Chemical nature unknown. PYROSMAi.rrE.— Analysis by Ludwig, SiO, 84G(i, FeO 27-05, MnO 25-()B, CaO 0-52, MgO 0-93 HiO 8-31, CI 4-88=101-85. In hexagonal tables. Color blackish-green. Nya-Koppai- berg, etc. , Sweden. \l APOPHYLHTE.* Tetragonal. O M-i = 128° 38'; c = 1-2515 rod. Streak uncolored. Crystals sometimes nearly cylindi'icul or barrel- shaped. Twins : twin- niug-plane the octahe- dron 1. Cleavage : highly perfect ; / less so. Also massive and lamellar. II. = 4-5-5. G. = 2-3- 2-4. Lustre of O pearly ; of the other faces vitre- ous. Color white, oi giayish ; occasionally with a greenish, yellow- ish, or rose- rod tint, flesh Transparent ; rarely opaque. Brittle. OXYGEN COMPOUNDS — HYDROUS SILICATES. 341 Oomp.— Q ratio for R : Si : H usually taken as 1 : 4 : 2, part of the oxygen replat.-ed by fcaorine (Fo). According to Rammelsberg the ratio is 9 : 82 : 16 ; he writes the formula 4(HoCaSi,0*o + aq) + KF. This requires: Silica 52 97, lime 24-72, potash 5-20, water lo-fiO, fluorine 2-10 = 100 '89. It maybe taken as a unisilicale if part of the silica is considered accessory. Pyr., etc— In the closed tube exfoliates, whitens, and yields water, which reacts acid. In the open tube, when fused with salt of phosphorus, gives a fluorine reaction. B. B^ exfoliates, colors the flame violet (i)otash), and fuses to a white vesicular enamel. F. =15. Decom- posed by hydrochloric acid, with separation of slimy silica. Diff. — Distinguishing characters : its occurrence in square prisms ; its perfect basal cleav- age, and pearly lustre on the base. Obs. — Occurs commonly in amygdaloid and related rocks, with various zeolites ; also occa- sionally in cavities in granite, gneiss, etc. Greenland, Iceland, the Faroe Islands, Andreas- berg, the Syhadree Mountains in Bombay, afford fine specimens. In America, found in Nova Scotia ; Bergen Hill, N. J.; the Cliff mine, Lake Superior region. CnALCOAfonPiniG (v. linth), from limestone inclosures in the lava of Niedermendg. Hexagonal. Essentially an hydrous calcium silicate. Edingtonite.— Analysis by Heddle, SiO, 3(j-98, AIO3 22-63, BaO 26-84, CaO tr, Na^O tr., HoO 12-46=98-91. Tetragonal. Dumbarton, Scotland. ars.MONDiTE.— Analysis. Madgnac, SiO, 35-38, AIO3 27-23, Ca013-12, K20 2-83, H,O21-10 = 100-18. Capo di Bove, near Rome ; Baumgarten, near Giessen, etc. Carpholite.— In radiated tufts in the tin mines of Schlackenwald ; Wippra in the Harz, Bases mostly in sesquioxide state (A:l,Mn,Fe). SUBSILICATES. (/" ALLOPHANE. Amorphous. In incrustations, usually thin, with a mammillary surface, and hyalite-like ; sometimes stalactitic. Occasionally almost pulverulent. H.=3. G. = l*85-1"89. Lustre vitreous to subresinous ; bright and waxy internally. Color pale sky-blue, sometimes greenish to deep o-reen, brown, yellow, or colorless. Streak uncolored. Translucent. Fracture imperfectly conchoidal and shining, to earthy. Very brittle. Comp — Q. ratio for Arl : Si : H, mostly=3 : 2 : 6 (or 5) ; AlSiOj+fiaq, or A:lSi05+5aq= Silica 23-75, alumina 40-62, water 35-63 = 100. Phimballophane, from Sardinia, contains a little lead. The coloring matter of the blue variety is due to traces of chrysocoUa, the green to mala- chite, and that of the yellowish and brown to iron. Pyr., etc — Yields much water in the closed tube. B.B. crumbles, but is infusible. Gives a blae color with cobalt solution. Gelatinizes with hydrochloric acid. Obs. — Allophane is regarded as a result of the decomposition of some aluminous silicate (feldspar, etc.) ; and it often occurs incrusting fissures or cavities in mines, especially those of copper and limonite, and even in beds of coal. Found at Schneeberg in Saxony ; at Gera- bach ; at the Chessy copper mine, near Lyons; near Woolwich, in Kent, England. In the U. S. it occurs at Richmond, Mass.; at the Friedensville zinc mines, Pa,, etc. COLI.YRITE. — A hydrous silicate of aluminum. Clay-like in structure, white. Hove, England ; Schemnitz. Uranophane, from Silesia, and Uranotile , from Wolsendorf, Bavaria, are silicates con taiuing uranium. 342 DESCRIPTIVE MINERALOGY. / II. Zeolite Section. THOMSONITE. Comptonne. Orthorhombic. /A /= 90° 40' ; 0^ l-l = 144° a' ; c\l'.d =0-7225 ; I'OllT : 1. Cleavage: i-l easily obtained ; *4 less sc ; O in traces. Twins : crncifoi-in, having the vertical axis in common. Also columnar, structure radiated ; in radiated spherical concretions ; also amorphous and compact. n. = 5-5*5. G. = 2-3-2-4. Vitreous, more or less pearly. Snow-white ; impure varieties brown. Streak uncoloi-ed. Transparent — translucent. Fracture uneven. Bi'ittle. Pyroelectric. Double I'cfraction weak ; optic- axial plane parallel to 0\ bisectrix positive, normal to i-l ; divero-ence S2°-82^° for red rays, from Dumbarton ; DesCl. Var. — Ordinary, {a) In regular crystals, usually more or less rectangular in outline, {h) Tn slender prisms, often vesicular to radiated, {c) Radiated fibrous, {d) Spherical concre- iions, consisting of radiated fibres or slender crystals, [e) Massive, granular to impalpable, and white to reddish-brown. Ozarkite is ma.ssive thomsouite ; rmiite (Norway) is related. Comp.— Q. ratio for Il( = Ca,Nao) : ^(Al) : Si : H=] : 8 : 4 : 2^, Ca : Na.;=2 : 1, or 3 : 1 ; formula 2(Ca,Nao)rVlSi20y + 5aq. Analysis, Rammelsberg, Dumbarton, SiOa 38*09, AlOs 31-62, CaO 12-(i0,'Na,O4G2, H.,0 13-40=100-20. Pyr., etc. At a red heat loses 13 3 p. c. of water, and the mineral becomes fused to a white enamel. B.B. fuses with intumescence at 2 to a white enamel. Gelatinizes with hydrochloric acid. Obs. — Found in cavities in lava and other igneous rocks ; and also in some metamorphic rocks, with elteolite. Occurs near Kilpatrick, Scotland ; in the lavas of ^omxaa, (comptonite) ; in Bohemia ; in Sicily ; in Faroe ; the Tyrol, at Theiss ; at Monzoni, Fassathal ; at Peter's Point, Nova Scotia ; at Magnet Cove, Arkansas {ozarkite). \J NATROLITE. Mesotype. Nadelzeolith, Germ. Orthorhombic. 640 It. I =21°, 6> A 14 = 144° 23'; c ; B :« = 0-35825 : 1*0176 : 1. Crystals usually slender, often acicular ; fre- quently interlacing ; divei'gent, or stellate. Also librous, radiating, massive, granulai', or compact. IL = 5-5-5. G. = 2-17-2-25 ; 2*249, Bergen Hill, Brush. Lustre vitreous, sometimes inclining to pearly, especially in fibrous varieties. Color white, or colorless ; also grayish, yellowish, reddish to red. Streak nncolored. Ti-ansparent — translucent. Double refraction weak ; op- tic-axial plane i-i] bisectrix positive, parallel to edge ///; axial divergence 94°-96'^, red rays, for Anvergne crystals; 95° 12' for brevicite; DesCl. Comp.— Q. ratio for R : R : Si : H=l : 3 : 6 : 2 ; and for R : Si= 2 : 3(R=Nao,3R=R) ; formula NajAlSiaO,o+2aq=Silica 4729, alumina 26-96, soda 16-30, water 9-45 = 100. Pyr., etc In the closed tube loses water, Avhitens and becomes opaque. B.B. fuses quictlj at 2 to a colorless glass. Fusible in the *larae of an ordinary stearine or wax caJidle. Gela tinizoB with acids. ^^-^ 7% P^ tt i\ /^ 1 11 t\ i) OXYGEN CO^IPOUNDS — HYDROUS SILICATES. 34) Dilf. — Some varietiea resemble pectolite, thomsonite, but distinguished B. R. Obs. — Occurs in cavities in amygdaloidal trap, basalt, and other igjneous rocks ; and some- timos in seams In granite, gneiss, and syenite. It is found in Bohemia ; in Auvergne ; Fassa thai, Tyrol ; Kapnik ; at Glen Faig in Fifeshire ; in Dumbartonshire. In Xorth America, occurs in the trap of Nova Scotia ; at Bergen Hill. X. J. ; at Copper Falls, Lake Superior. t/s SCOLECITE. Poouahlite. 2. C= 89° 6', lAl= 91° 36', 6> A l-l = 161° 16^' ; c : •0282 : 1. Crystals loiior or slioi't prisms, or l:a Monocliuic. acicular, rarely well terminated, and always compound. Twins: twinning-plane ^-^. Cleavage: /nearly perfect. Also in nodules or massive; iibntns and radiated. PL=5-5-5. G. = 2"16-24. Lustre vitreous, or silky when Hbrous. Transparent to sul)transliiceut. Pyro- electric, the free end of the crystals the antilogne pole. Double refraction weak ; optic-axial plane normal to i-l ; divergence 53° 41', for the red i ays ; bisectrix negative, paraltel to i-l ; plane of the axis of the red rays and their bisectrix inclined about 17° 8' to i-i, and 93° 3' to l-^. Comp.— Q. ratio f or R : R : Si : H=l : 3 : 6 : 8 ; forR,3R=R) : Si=2 : 3, as in natrolite ; R— Ca,R=:r^l; formula CaiySiaOio+^aq^Silica 45 85, alumina 2[j"13, lime 14 26, water 13 -76 = 100. Pyr., etc. — B.B. sometimes curls up like a worm (whence the name from (tk'mKv^, a worm, which gives scohcite, and not scole^ite or scolezUe) ; other varieties intumesce but slightly, and all fuse at 2-2 2 to a white blebby enamel. Gelatinizes with acids like natrolite. Diff. — Characterized by its pyrognostics. Obs. — Occurs in the Beruflord, Iceland ; also at Staff a ; inSkye, atTalisker ; near Poonah, llindostan {Poouahlite) ; in Greenland ; at Pargas, Finland, etc. Mesolite. — (Ca.Na-^-'^lSisOio+oaq (5 p. c. Xa-iO). Near scolecite. Iceland; Nova Scotia. Levtnite. — Rhombohedral. Q. ratio f or R : fi : Si : H=l : 3 : 6 : 4. Analysis, Damour, Iceland, SiOa 4576, i^Oa 23 06, CaO 10 57, Na.O 136, K^O 1-64, H.O 17 33 = 100-22. Ire- land ; Faroe ; Iceland. /, ANALCITE.* Isometric (?) . Usually in trapezohedrons (f. 54, p. 18). Cleavage; cubic, in traces. Also massive granular. n. = 5-55. G. = 2-22-2-29 ; 2-278, Thomson. Lustre vitreous. Color- less ; white ; occasionallj' grayish, greenish, yellowish, or reddish-white. Streak white. Transparent — nearly opaque. Fracture subconehoidal, uneven, Lrittle. Oomp.— Q. ratio f or R : R : Si : H=l : 3 : 8 : 2, R=Nao, R=A1=3R ; R : Si=t : 2. For mula Na^rVlSijO, 2 f2aq= Silica 54-47, alumina 23-29, soda 14-07, water 817 = 100. Pyr., etc. — Yields water in the closed tube. B.B. fuses at 2-5 to a colorless glass. Gelati- nizes with hydrochloric acid. Diff. — Distinguishing characters : crystalline form ; absence of cleavage ; fusion B.B. t«YA- imt intumescence to a clear glass (unlike chabazite). Obs. — Some localities are : the Tyrol ; the Kilpacnck Hills in Scotland ; the Faroe Islands ; Iceland ; Ausaig, Bohemia ; Nova Scotia ; Bergen Hill, New Jersey ; the Lake Superior region. Schrauf has found that the analcite ol r rieueck, Bohemia, is properly tetragonal ; th« (simplest crystals showing evidence of repeated iwmning. 344 DESCRIPTIVE MINERALOGY. Faujasite. — An octahedral zeolite from the Kaiserstuhlgebirge. Analysis, Damour, SiOi 46-12, AIO3 16-81, CaO 479, Na,0 509, HoO 27 02 = 99-83. EUDNOPHITE. Near analcite. In syenite near Brevig, Norway. PlLlNlTE. —In slender needles (orthorhombic) ; white; lustre silky. Analysis SiOa 55 "70, AlOsCFeOa) 18-64, CaO 19.51, Li^O (1-18), H5O 4-97=100. In granite of Striegau, SUesia [Lasaulx). CHABAZITE.* Rhombohedral. i? A ^ = 94° 4G', 6> A ^ = 129° 15' ; c = 1*06. Twins : twinning-plane 0, very common, and usually in compound twins, as in f. 644 ; also _S, rare. Cleavage rhombohedral, rather distinct. 642 Haydenite. H.=4-5. G. = 2-08-2-19. Lustre vitreous. Color white, flesh-red ; streak uncolored. Transparent — translucent. Fracture uneven. Bnttle. Double refraction weak ; in polarized light, images rather confused ; axis in some crystals (Bohemia) negative, in otliers (from Andreasberg) posi- tive ; DesCl. Var. — 1. Ordinary. The most common form is the fundamental rhombohedron, in which the angle is so near 90'' that the crj'stals were at first mistaken for cubes. Acadialite, from Nova Scotia (Acadia of the French of last century), is only a reddish chabazite ; sometimes nearly colorless. In some specimens the coloring matter is arranged in a tesselated manner, or in layers, with the angles almost colorless. 2. PhacoUte is a colorless variety occurring in twins of mostly a hexagonal form, and often much modified so as to be lenticular in shape (whence the name, from tta/coy, a bean) ; the original was from Leipa in Bohemia; HaU =94° 24', fr. Oberstein, Breith. Comp.— Making part of the water basic (at 300'' C lo.ses 17-19 p. c. ) Rammelsberg writes the formula (H,K),CaA:lSi50,6+6aq, where theQ. ratio for R : R : Si = 2 : 3 : 10, R .= H,,Na2, Ca; or (3R=R), R : Si=l : 2. The formula corresponds to Silica 5050, alumina 17-20, lime 9-43, potash 1-98, water 2083 = 100. Pyr., etc. — B.B. intumesces and fuses to a blebby glass, nearly opaque. Decomposed by hydrochloric acid, with separation of slimy silica. Diff. — Its rhombohedral form, resembling a cube, is characteristic ; is harder, and does not effervesce with acids like calcite ; is unlike fluorite in cleavage; fuses B.B. with intumes- cence to a blebby glass, unlike analcite. Obs. — Chabazite occurs mostly in trap, basalt, or amygdaloid, and occasionally in gneiss, syenite, mica schist, hornblendic schist. At the Faroe Islands, Gr>enland, and Iceland ; at Aussig in Bohemia ; Striegau, Silesia. In Nova Scotia, wine-yellow or tlesh-red (the last the acadi(d'ite), etc.; at Bergen Hill, N. J.; at Jones's Falls, near IJaltimore (haydenite). Seebaciiite (Bauer j from Richmond, Victoria. . is, according to v. Rath, identical with phacolite ; and h» suggests the same may be true of herschelite, from Aci Castello, Sicily. OXYGEN COMPOUNDS— HTDROrS 8ILTCATE8. 345 r^^^-"^. aMELINITE. llhorabohedral. IiAB = 112° 20', OaB= O A-1 = 140" 3' ; 6 0*7254. Crystals usually hexagonal in aspect ; sonie- ciines habit rlioinboliedral; i often horizontally stri- ated. Cleavage: i perfect. Observed only in crystals, aud never as twins. H.=4-5. G. = 2-04-2-17. Lustre vitreous. Colorless, yellowish- white, greenish - white, reddish-white tiesh- red. Transparent to trans- lucent. Brittle. C. Blomidon, etc. C. Blomidon. Oomp.— Q. ratio forR : R : Si : H=l : 3 : 8 : 0, Il=Ca(Na.,KO, R=A1. Fonnula (Ca,Na2i .WSi^O.^ + Gaq. Analysis by Howe, Berg-en Hill, SiO. 48-67, AIO3 18-73, FeOs 010, CaO 2-60, Na,0 9-14, H,0' 21 -35 = 100 -08 (Am. J. Sci.. III., xii., 270, 1876). Pyr., etc. — In the closed tube crumbles, gives ofE much water. B. B. fuses easily to a white enamel. Decomposed by hydrochloric acid with gelatinization. DiS. — Closely resembles some chabazite, but differs decidedly in angle. Obs. — Occurs at Andreasberg; in Translyvania ; in Antrim, Ireland ; near Lame ; at Talisker in Skye ; at Cape Blomidon and other localities in Nova Scotia {ledererite) ; in fine crystals of varied habit at the Bergen Hill tunnel of 1876. PHILLIPSITE.* Orthorhombic. /a/= 91° 12' ; 1 A 1 = 121° 20', 120° 44', and 88° 40' Marignac. Faces 1 and i-l striated parallel to the edge between them. Simple crystals nn- 647 known. Commonly in cruciform crystals, consist- ing of two crossing crystals, each a twinned prism (f. 647). Ciystals either isolated, or grouped in tufts or spheres that are radiated within and bristled with angles at surface. II. =4-4-5. G.=2'2U1. Lustre vitreous. Color white, sometimes reddish. Sti-eak un- colored.' Translucent — opaque. Comp — Q. ratio for R : ft : Si : H=:l : 3 : 8 : 4, R=Ca and KslNa,) ; Ca : K.=3 : 1, 2 : 3, etc.. Fonmila RAlSi40,a -h4aq. Analysis by Ettling. Nidda. Hessen, SiOa 48 13, AlOa 21-41, CaO 8-21, K3O 5 20, Na.O 0'70, H,0 16 78= 100-48. Pyr.. etc. — B.B. crumbles and fuses at 3 to a white enamel. Gelatinizes with hydrochloric acid. DIff. — Resembles harmotome, but distinguished B.B. Obs. — At the Giant's Causeway, Ireland ; at Capo di Bove. near Rome ; in Sicily ; Annerode, near Giessen ; in Silesia ; Bohemia ; on the west coast of Iceland. Streug (Jahrb. Min., 1876, 585) shows that the forms are exactly analogous to those of harmotome, and suggests that it may be also monoclinic. C. di Bove. 3^6 DESCRIPTIVE MmEKALOGY. ^ HARMOTOME. Monoclinic (DesCloizeaux). Cleavage /, 0^ easy. SiinjDle ciystals un- known. Occurring in penetra- tion-twins. Unknown massive. H. =4-5. G. =2 -44-2 -45. Lustre vitreous. Color white ; passing into gray, yellow, red, or brown. Sti-eak white. Sub- transparent — translucent. Fj-ac- ture uneven, imperfectly con- ^ __^ . ._ , , choidal. Brittle. ^^-i->^Z^ "^''^^^::::::r45=^ Comp.— Q. ratio for R : ft : Si : H c ,. A J 1 =1 : 3 : 10 : 5: here Il=Ba mostly, Strontian. Andreasberg. ^j^^ K. ; R=A1. Formula RiVlSi^O,; -|-5aq. If one-fifth of the water ia chemically combined (Rammelsberg), then the formula corresponds to HoR7\lSi60,B+4aq. Both formulas give Silica 45-91, alumina 15'70, baryta 20-0(), potash 8o4. water 14-99 = 100. Pyr., etc. — B.B. whitens, then crumbles and fuses at 8'5 without intumescence to a white translucent glass. Some varieties phosphoresce when heated. Decomposed by hydrochloric acid without gelatinizing. Diff- — Characterized by its crystallization in twins ; the presence of barium separates it from other species. Obs — Harmotome occurs in amygdaloid, phonolyte, trachyte ; also on gneiss, and in some metalliferous veins. At Strontian in Scotland ; at Andreasberg ; at Rudelstadt in Silesia , Schiffenberg, near Giessen, etc. ; Oberstein ; in the gneiss of upper New York City. DesCloizeaux, who has shown the monoclinic character of the species by optical means, has adopted a different position for the crystals (1=/, etc.). ^ STILBITE.* Desmine. 6o0 Orthorhombic. iKl- 94° 16', 1 A 1, front, = 119° 16', side, 114° 0'. Cleavage : i-l pei-fect, i-\ less so. Forms as in f. 650 ; more common with the prism flattened parallel to i-l or the cleavage-face, and jiointed at the extremities. Twins: cruciform, twinning-plane. 1-i, rare. Common in sheaf-like aggregations ; divergent or radiated ; some times globular and thin lamellar-columnar. ri. = 3-5-4. G.=:2-004-2-205. Lustre of z-i pearly , of other faces viti'eous. Color white ; occasionally yellow, brown, or red, to brick-red. Streak uncolored. Transparent — translucent. Fracture uneven. Brittle. Var. — 1. Ordinary. Either {n) in crystals, flattened and pearly parallel to the plane of cleavage, or sheaf -like, or divergent gi'oups ; or ib) in radiated stars or hemispheres, with the radiating individual* showing a pearly cleavage surface. Sjyhan'ostilbite, Beud, is in spheres, radiated within with a pearly fracture, rather soft externally. Comp.— Q. ratio for R : ft : Si : H=l : 8 : 12 : G ; R=Ca(Nao),ft=:7Vl. Formula RAlSiaO,, -f 6aq. If two parts of water are basic (Ranim.) the ratio becomes (R=Ca,Ho.Na2) 3 : 8 : 19 : 4, or R : Si=l : 2, and the formula if* HiRMSinOi6-f-4aq. Analysis, Petersen, Seisser AlpV* SiOo 55-61, AlOs 15 02, Ca0 7:33, Na,.0 2 01, K.O 0-47, H,0 18-19=99-23. Pyr., etc. — B.B. exfoliates, swells up, curves into fan-like or vermicular forms, and fus«B \ -1 OXYGEN COMPOUNDS HTDEGUS SIMCATES. 347 to a white enamel. F. =3-2-5. Decomposed by hydrochloric acid, without gelatinizing. The spkcerostilbite gelatinizes, but Heddle says this is owing to a mixture of mesolite with the stil- bite. Di£f. — Prominent characters: occurrence in sheaf -like forms, and in the rectangular tabular crystals ; lustre on cleavage-faoe pearly ; does not gelatinize with acids. Obs. — Stilbite occurs mostly in cavities in amygdaloid. It is also found in some metal- liferous veins, and in granite and gneiss. The Faroe Islands, Iceland, and the Isle of Skye ; in Dumbartonshire, Scotland ; at Andreasber:? ; Arendal in Norway ; in the Syhadree Mts., Bombay ; near Fahlun. in Sweden. In North America, at Bergen Hill, New Jersey ; at the Michipicoten Islands, Lake Superior ; Nova Scotia, etc. The name stilbite is from ariXSr/, lustre; and desmine txoxa. (^ta^u?}, a bundle. The species etilbite, as adopted by Haiiy, included Strahlzeolith Werii. (radiated zeolite, or the above), and Blatterzeolith Wer/i. (foliated zeolite, or the species heulaudite beyond;. The former was the typical part of the species, and is the first mentioned in the description ; and the lattei he added to the species, as he observes, with much hesitation. In 1817, Breithaupt separated the two zeolites, and called the former desmine and the latter euzeolite, thus throwing aside entirely, contrary to rule and propriety, Haiiy' s name stilbite, which should have been accepted by him in place of desmine. it being the typical part of his species In 1822, Brooke (ap- parently unaware of what Breithaupt had done) used stilbite for the first, and named the other heulandit". In this he has been followed by the French and English mineralogists, while the Germans have unfortunately followed Breithaupt. Epistilbite (/?m«'0 9.35, F tr=10d-33. Pyr., etc. — Yields water. B.B. fuses to a white blebby glass. Not acted upon by acids. Pyrargillite is difficultly fusible, but is completely decomposed by hydrochloric acid. Obs. — Fahlunite (and tridasite) from Fahlun, Sweden. The following are identical, or nearly so: Esmarkite and praseoUte, Brevig; raumite, Raumo, Finland; cIdorojjhyUite, JJnity, Me. ; pyrargillite, Helsingfors ; polychroilite, Krageroe, and aspasioUte^ Norway ; huronite, Lako Huron ( Weissite^ Fahlun). MARGARODITE. Like muscovite or common mica in crystallization, and in optical and other phj'sical characters, except usually a more pearly lustre, and the color more commonly whitish or silvery. C6mp.— Q. ratio for R : R : Si : H mostly 1:6:9:3; whence the formula H.RsAliSiaOsg, the water being basic. Sometimes Q. ratio 1 : 9 ;12 : 2; but this division belongs with damourite, if the two are distinguishable. This species appears to be often, if not always, a result of the hydration of muscovite, there being all shades of gradation between it and that species. Jluscovite has the Q. ratio for bases and silicon of 4 : 5, or nearly. Analysis, Smith and Brush. Litchfiold, Ct., SiO., 44(;0, Al^Oa 3a-33,Fe.,03l-34,MgO 037, CaO 0-50, Na204-lO, K,0 6 20, H,0 5-26, P tr.^ 100-60. For pyrognostics and localities, see muscovite, p. 313. GiLBERTiTE. — Essentially identical with margarodite ; tin mines, Saxony. V DAMOURITJEJ. An aggregate of fine scales, mica-like in structure. H. = 2-3. G,=: 2*792. Lustre pearly. Color yellow or yellowish- white Optic-axial divergence 10 to 12 degrees ; for sterliugite 70°. Comp. — A hydrous potash-mica, like margarodite, to which it is closely related. Q. ratio 23 354 DESCRIPTIVE AIINERALOGY. for R : 11 : Si : H=:l : 9 : 12 : 2, or 1 : 1 for bases to silicon, if the water is basic. Formula HiKoAlsSieOai. Analysis, Monroe, from Sterling, Mass. (sterlmgiie), SiOa43"87, AlOsBG'iS. FeOa 3-36, K.2O 10 86, HoO 519=99-73. It is the gangne of cyanite at Pontivy in Brittany; and the same at Horrsjoberg, Werm- land. Associated with corundum in North Carolina; with spodumene, at Sterling, Mass. PARAGONITE. Pregrattite. Cossaite. Massive, sometimes consisting distinctly of fine scales ; the rock slaty 01 Bchistose. Cleavage of scales in one direction eniiiient, mica-like. II. = 2-5-3. G. = 2-779, paragonite; 2 S95, pregrattite, CEllacher. Lustre strong pearly. Color yellowish, grayish, grayish-wliite, greenish, light apple- greeu. Translucent ; single scales transparent. I Comp A hydrous sodium mica. Q. ratio for R : fi : Si : H=l : 9 : 12 : 2, or 1 : 1 for bases and silicon, if the water be made basic. Formula H4Nao2Vl3Si6024(K : Na=l : 6)= Silica 46-60, alumina 39-96, soda 690, potash 1 74, water 4-80=100. Pyr. — B.B. the paragonite is stated to be infusible. The pregrattite exfoliates somewhat Uke vermiculite (a property of some clinochlore and other species), and becomes milk-white on the edges. Obs. — Faragonite constitutes the mass of the rock at Monte Campione, in the region of St. Gothard, containing "cyanite and staurolite, called paragonitic or talcose schist. The pregrattite is from Pregratten in the Pusterthal, Tyrol ; co-saite, from mines of Borgofranco, near Ivrea. IviGTiTE. — Occurs in yellow scales, also granular, with cryolite from Greenland. EUPHYLiiiTE. — Associated with tourmaline and corundum at Unionville, Perm. Q. ratio for R:K:Si:H=l;8:9:2. Average composition, Silica 41 '6, alumina 42 3, lime 1'5, potash 3 2, soda 5-9, water f)-o = 100. Ephesite, LEsiiEYi'i'E. — Hydro -micas, perhaps identical with damourite. Occur with corundum, and impure from admixture -with it. OilLLACnERlTE. — A hydro-mica, containing 5 p. c. baryta. Pfitschthal, Tyrol. CooKEiTE. — A hydrous lithium mica. From Hebron and Paris, Me., apparently a pro- duct of the alteration of rubellite. HISINaERITE. Amorphous, compact, without cleavage. II. = 3. G. = 304:5. Lustre greasy, inclining to vitreous. Color black to brownish-black. Streak yellowish-brown. Fractnre conchoidal. Comp.— Q. ratio for R+li : Si : H=:2 : 3 : 3 ; formula R6ft2Si30iB-l-4aq (with one-tliird of the water basic). R=Fe,H. ; ft=Fe. Analysis, Cleve, from Solberg, Norway, SiO-35-33, FeOs 32-14, FeO 7-08, MgO 3-'00, H,0 2204=100-19. Pyr., etc. — Yields much water. B B. fuses with difficulty toya black magnetic slag. With the fluxes gives reactions for iron. In hydrochloric acid easily decomposed without gelatin- izing. Obs. — Found at Longban, Tunaberg, Sweden ; Riddarhyttan ; at Degeri) (degeivite), neai Helsicgfors, Finland. Ekmannite. — Foliated, also radiated. Color green, resembles chlorite. Analysis, Iget Btrom, SiO, 3430, FeOa 497, FeO 35-78, MuO 1145, MgO 299, H,0 1051 = 100. With magnetite at Grythyttan, Sweden. Neotocite. — Uncertain alteration-products of rhodonite; amorphous. v>on tains 20-30 p. c. MnO. Paisberg, near Filipstadt, Sweden ; Finland, etc. GiLLrNGiTE ; Sweden. Jollyte ; Bodenmais, Bavaria. OXYGEN COMPOUNDS — IIYDEOrS SILICATES. 355 Venniculite Group.* The vERMicuLTTKS liavG a micaceous sti-uctnre. The}' are all unisilicates, having the f^eiieral quaiitivalent ratio H + R : Si : 11 = 2 : 2 : 1, the water being solely water of crystallization. The varieties differ in the ratio of the bases present in the protoxide and sesquioxide states.* V JEFFERISITE. Orthorhoinhic (?). In broad cr^'stals or crystalline plates. Cleavage : basal eminent, afford'ng easih' very thin folia, like mica. Surface of plates often triangularly marked, by the crossing of lines at angles of 60° and 120°. H. = 1'5. G. = 2"30. Lustre peai-ly on cleavage surface. Color dark yellowish-brown and brownish-yellow; b'ght yellow by transmitted light. Transparent only in very thin folia. Flexible, almost brittle. Optically biaxial : DesCl. Plates often several inches acrosSi 3.andforR+ft : Si : H = 3 : 2 : 1. Color green. Elba. CuoNiCKiTE, V' Comp.— Q. ratio for R : R : Si : H=3 : 3 : 5 : 2^, and R f R : Si : H=2 : 3 : 1 ; whence R4RoSio0.o-)-5aq. Analysis: Brush, Westchester, SiOo 37-10, AIO3 17-57, FeOs 10-54, FeO 1-26, MgO 19-05, CaO 0-50, Na.O tr., K.O 0-43, H,0 13-70=100 87. Pyr., etc. — When heated to 300° C. exfoliates very remarkably (like verraictdite) ; B.B. in fo'-ceps after exfoliation becomes pearly-white and opaque, and ultimately fuses to a dare gray mass. With the fluxes reactions for silica and iron. Decomposed by hydrochloric acid. Obs. — Occurs in veins in serpentine at Westchester, Pa. Pyroscl,p:ritk. -Q. mtio for R : R : Si : H=4 : 2 : (5 Silica 08-9, alumina 14-8, magnesia 346, water 11 "7 = 100. also Elba, has the ratio 3:2:5:2. Vermiculite.— Q. ratio for R : R : Si : H=4 : 3 : 6 : 3. Milbury, Mass. Culsageeitb. Q. ratio R : R : Si : H=2 : 1 : 1 : 1. Jeuk's mine. N. C. Hallite, same ratio=2 : 1 : 3 : 2. East Nottingham, Chester Co., Penn. Peliiamite, same ratio = : 4 : 10 : 5. Pelham, Mass. Similar mineral from Lenni, Delaware Co., Pa., above ratio=6 : 4 : 10 : 5. In all of the .above R = Mg mostly, and R=A1 and Fe. Kerrite. — q! ratio=6 : 3 : 10 : 10 ; and Maconite, Q. ratio=3 : 6 : 8 : 5, are both from Culsagee mine, Macon Co., N. C. VAALTfE, Q. ratio=6 : 3 : 10 : 4. South Africa. Dxabantite, Haices (diabantachromyn, Liebc). — Fills cavities in amygdaloidal trap. Color dark green. Q. ratio for R:R:Si:H=4:2:G:3, but iron a more prominent ingre- dient than in pyi-osclerite (see above). Analysis : Hawes, Farraington, Ct., 5 SiO. 33 68, AlOj 10-84, FeOs 2-86, FeO 24-33, MnO 038, CaO 073, MgO 16-52, Na,0 0-33, HaO 10-02=99-69. StJBSILICATES. ChloritQ Group. ^PENNINITE. Kiimmererite. Khombohedral. li A R-G5° Cleavage ; basal, highly perfect, groups. Also massive, consisting pact cryptocry stall ill e. 36', O AjR = 103° 55 ; c = 3-4951. Crystals often tabular, and in crested of an aggregation of scales ; also com- * These relations were brought out by Cooke, ibid,, 1875. 453. Proc. Amer. Acad., Boston, 1871, 35; 356 DESCRIPTIVE SnXEKALOGT. 652 653 II. = 2-2*5 ; 3, at times, on edges. G.=2'6-2-85. Lustre of cleavage sui-face pearly ; of lateral plates viti eons, and sometimes brilliant. Color green, a])ple-green, grass- gi'cen , gray isli-green , olive-green ; also reddish, violet, rose-red, pink, giayish-i'ed ; occasionally yellowish and silvei- white; violet crystals, and sometimes the green, hyacinth-i-ed by trans- mitted light along the vertical axis. Transparent to snbtranslu cent. LamintXi flexible, not elastic. Donble refraction feeble; axis either negative or positive, and sometimes positive and negative in different lamina3 of the same plate or crystal. Comp. — Q. ratio for bases and silicon 4 : 3, but varying from 4 : 3 to 5 : 4. Exact deduc- tions fiom the analyses cannot be made until the state of oxidation of the iron in all cases is ascertained. Analysis: Schweizer, from Zermatt, SiO. 38-07, AIO3 969, FeO 11-36, MgO 33-34, H,0 12 -58 = 99 -08. Pyr., etc. — In the closed tube yields water. B.B. exfoliates somewhat and is diflRcnltly fusible. With the fluxes all varieties give reactions for iron, and many varieties react for chromium. Partially decomposed by acids. Obs. — Occurs with serpentine in the region of Zermatt, Valais, near Mt. Rosa ; at Ala, Piedmont ; at Schwarzenstein in the Tyrol ; at Taberg in Wermland ; at Snarnm. Kdm,' mererite is found near Miask in the Urals; at Haroldswick in Unst, Shetland Isles. Abun- dant at Texas, Lancaster Co., Pa., along with clinochlore, some crystals being imbedded in clinochlore, or the reverse. The following names belong here: tabergite ; psttidopJiite, compact, massive {allopJdte)\ hganite. Dclessite, euralite, aphrosiderite, chlorophmte are chloritic minerals, occurring under simi- lar conditions, in amygdaloid, etc REPIDOLITE. Clinochlore. Klinochlor, Oerm. MonocHnic. C = 62° 51' = 6» A i-i, lhl= 125° 14': c 655 Achmatovsk. 37', 6> A 44 = 108° \ h : d = 1-47756 : 1-73195 : 1. Cleavage : eminent ; crystals often tab- nlar. also oblong ; frequent- ly rhombohedial in aspect, the plane angles of the base being 60° and 120°. Twins: twinning-plane 3, making stellate groups, as in f. 656, 657, very common. Crystals often grouped in rosettes. Massive coarse scaly frranular to fine granular and Achmatovsk. earthy. Il. = 2-2-5. G.=2-65-2-78. Lv'.ttre of cleavage-face somewhat pearly. Color deep grass-green to olive- green ; also rose-red. Often strongly dichroic. Streak greenish-white to uncolored Transparent to translucent. Flexible and somewhat elastic OXYGEN COMPOUNDS — HYDKOTJS SILICATES. 357 6:4; corresponding to MgoAlSisOiH^aqn G5^ \ Texas. Comp.— Q. ratio for R : R : Si : H=5 : 3 Silica '32'~), alumina 18 '0, magnesia 36 "0, water 12-9 = 100. Sometimes part of the Mg ggg is replaced by Fe. Pyr., etc. — Yields water. B.B. in the platinum forceps whitens and fuses with difficultj' ou the edges to a grayish-black glass. With borax a clear glass colored by iron, and sometimes chromium. In svd- phuric acid wholly decomposed. The variety from Willimantic. Ct., exfoliates in worm- like forms, like vermiculite. Obs. — Occurs in connection with chloritic and talcose rocks or schist, and serpentine. Westohpster Found at Achmatovsk ; Schwarzenstein ; Zillerthal, etc. ; red [koUchubeite) in the dis- trict of Ufaleisk. Southern Ural; at Ala, Piedmont; at Zermatt ; at Marienberg, Saxony. In the U. S. , at Westchester and Uniouville, and Texas, Pa. ; Brewster, N. Y. Named ripidolite from pi-iq^ a fan, in allusion to a common mode of grouping of the crys- tals. Leucutenbergite. — A prochlorite with the protoxide base almost wholly magnesia. Slatoust, Urals. PROCHLORITE. Hexagonal (?). Cleavage : basal, eminent. Crystals often implanted hy their sides, and in divergent groups, fan-shaped, or spheroidal. Also in large folia. Massive granular. H. = l-2. G.=2-78-2-06. Translucent to'opaque; transparent only in very thin folia. Lustre of cleavage surface feebly pearly. Color green, grass-green, olive-green, blackish-green; across the axis by transmitted light sometimes red. Streak uncolored or greenish. Laminae flexil^le, not elastic. Double refraction very weak ; one optical negative axis (Dauphiny) ; or two very slightly diverging, apparently normal to plane of cleavage. Comp. — Q. ratio for R : R : Si : H=12 : 9 : 14 : 9| ; for bases and silicon 3 : 2. Average composition = Silica 26 "8, alumina 197, iron protoxide 27 '5, magnesia 15'3, water 107=100. Pyr., etc. — Same as for ripidolite. Obs. — Like other chlorites in mode of occurrence. Sometimes in implanted crystals, as at St. Gothard, etc. ; in the Zillerthal, Tyrol; Traversella in Piedmont; in Styria, Bohemia. Also massive in Cornwall, in tin veins (where it is called peach) ; at Arendal in Norway. Cronstkdtite.— Q. ratio R : R : Si : H=3 : 3 : 4 : 3. Przibram; Cornwall. Stkigovite. — Q. rations : 2 : 4 : 2. In granite of Striegan, Silesia. Grochauite same locality. ^ MARGARITE. Perlglimmer, Germ. /A/=119°- 659 Orthorhombic (?) ; hcmihedral, with a monoclinic aspect. 120°. Lateral planes horizontally striated. Cleavage: basal, eminent. Twins: common, composition-face /, and forming, by the crossing of 3 ci-ystals, groups of 6 sectors. Usuallv in intersectinc: or airo'reo'ated laminaj; sometimes massive, with a seal}' structure. H.=3-5-4-5. G. = 2-99, Hermann. Lustre of base pearly, laterally vitreous. Color grayish, red- dish-white, yellowish. Translucent, subtranslucent. Laminae rather brittle. v/ 358 DESCRIPTIVE MINEEALOGT. Optic-axial angle very obtuse ; plane of axes parallel to the longer diagonal ; dispersion feeble. Comp. — Q. ratio for R : R : Si : H=l : 6 : 4 : 1 ; whence, if the water be basic, for basea andsilicon=:3 : 1, formula RftSiOe ; that is, HCartl.^SiOio. Aualj'sis, Smith, Chester, Mass., SiOo 32-21, 7^103 48-87, FeOa 2-50, MgO 0-32, CaO 10 02, Na,0(K,0) 101, H,0 4-61, Li,0 0-32, MuO 0-20:= 100 -96. Pyr., etc. — Yields water in the closed tube. B.B, whitens and fuses on the edges. Obs. — Margarite occurs in chlorite from the Greiner Mts. ; near Sterzing in the Tyrol ; at different localities of emery in Asia Minor and the Grecian Archipelago ; with corundum in Delaware Co., Pa.; at Unionville, Chester Co., Pa. (coriindellite); in Madison Co. [ding- manite), and elsewhere in North Carolina ; at the emery mines of Chester, Mass. OHLORITOID. Monoclinic, or trielinic. I A I' about 100° ; O (or cleavage surface) on lateral planes 93°-95°, DesCl, Cleavage: l)asal perfect: parallel to a lateral plane inipei'fectt. Usually coarsely foliated massive ; folia oftei curved or bent, and brittle; also in thin scales or small plates disseminatec through the containing rock. H. = 5"5-6. G. = 3*5-3'6. Color dai-k gray, green ish-gi-a}', greenish- black, grayish-black, often grass-green in vei-y thin plates ; stj-ongly dichroic. Streak uncolored, or gi-ayish, or very slightly greenish. Lustre of surface of cleavage somewhat pearly. Brittle. Var. — 1. The original cJiloritoid (or chloritspath) from Kossoibrod, near Katharinenburg in *he Ural. 2. The Sismondine, from St. Marcel. 3. Masoidte, from Natic, R. I., in very broad plates of a dark grayish-green color. The Canada mineral is in small plates, one-fourth in. wide and half this thick, disseminated through a sch\gt (like phyllite), and also in nodules of radiated structure, half an inch through. That of Gumuch-Dagh resembles sismondme, is dark green in thick folia and grass-green in very thin. Comp. — Q. ratio for R : ft : Si : H = l : 3 : 2 : 1, for mcst analvses. Analysis by v. KobeU, Bregratten, SiO, 2019, AIO3 38-30, ¥eO^ « 00. FeO 21 11, MgO 330, H..0 5 00=100 40. Pyr., etc — In a matrass yields water. B.B. nearly infusible ; becomes darker and magne- tic. Completely decomposed by sulphuric acid. The masouite fuses with difficulty to a dark green enamel. Obs. — The Kossoibrod chloritoid is associated with mica andcyanite ; the St. Marcel occurs in a dark green chlorite schist, with garnets, magnetite, and pyrite ; the Rhode Island, in an argillaceous schist ; the Chester, Mass. , in talcose schist, with emer.y, diaspore, etc. Phyllite {ainA ottrelite) closely resembles chloritoid, though the analyses hitherto made show a wide discrepancy, perhaps from want of purity in the material analyzed. Occurs in small, oblong, shining scales or plates, in argillaceous schist. Color blackish gray, greenish -gray, black. Phyllite occurs in the schist of Sterhng, Goshen, Chesterfield, Plainfield, etc., in Massachusetts, and Newport, R. I. {newportite). Ottrelite is from a similar rock near Ottrez. Seybektite. — Orthorhombic. I ,\ 1 = 120". In tabular crystals, sometimes hfxagonal ; also foliated massive ; sometimes lamellar radiate. Cleavage : basal perfect. Structure thin foliated, or micaceous parallel to the base. H. =4-5. (i. =3-3-1. Lustre pearly submetallic. Color reddish-brown, yellowish, copper-red. Folia brittle. Analysis. Brush, Amity, SiOa 80-24, AIO3 39-13, FeO., 3-27, MgO20-84, CaO 13-69. H,0 1-04. Na.>0 K_0, 1-43, ZrO, O-lo^ 100*39. Amity, N. Y. {clintoniid} ; FassiSLthal {bra ndisitei; Slaioust (xaut/io-p/ipUite). COKUNDOVIIILITE.--A chlorite with the Q. ratio=l : 1 : 1 : f . Occurs with corundum at Aflheville, N. C; Chester, Mass. DuDLEYiTE. — Alteration product of margarite. Clay Co., N. C. ; Dudleyville, Ala. WiLLCoxiTE. — Near margarite. Decomposition product of corundum. Q. ratio for R : R : Si : H=3 : 6 : 5 : 1. TnuRiNGiTE.— Q. ratio 2:3:3:2. Contains principally iron (Fe and Fe). Hot Springs^ Arkansas; Harper's Ferry ipwenite). Patternonite from Unionville, Pa., near thuringite. OXTOEN COMPOUNDS. — TANTALATES. C0LUMBATE8. 359 2. TANTALATES, OOLUMBATES. PYROCHLORE.* Isometric. Commonly in octahedrons. Cleavage: octahedral, some- times distinct, especially in the smaller crystals. jj _5_5.5^ G.=4-2-4-35. Lustre vitreous or resinous. Color brov/n, dark reddish- or blackish-brown. Streak light brown, yellowish- brov//i. Subtranshicent — opaque. Fracture conchoidaL Comp.— A columbate of calcium, cerium, and other bases in varying amounts. Analyi-is, by Rammelsberg. Brevig, CbO, oS^T, TiO, 5-^8, ThO^ 4 9(5, CeO 550, CaO 10-93, FeO.UOa) 5-53, NaO 5 31, F8-75, H,0 1-53=10M0. . Obs.— Occurs in syenite at Friederichsvarn and Laurvig, Norway; at Brevig; near Miask in the Urals ; Kaiserstuhlgebirge in Breisgau {koppite) ; with samarskite in N. Carolina (G-.= 4'794, chemical character unknown). MiCROLiTE.* — In minute yellow octahedrons in feldspar. G.=5o. Near pyrochlore, but probably coutaining more tantalum pentoxide. Chesterfield, Mass. PYRRiiri'E.— In isometric octahedrons. Color orange-yellow. Chemical character un- known. From Mursinsk in the Ural. A mineral supposed to be similar from the Azorea contains essentially, according to Hayes, colurabium, zirconium, etc. AzoRiTE. — In minute tetragonal octahedrons resembling zircon. From the Azores in albito. Chemical character unknown. v; 660 TANTALITE.* Orthorhombic. Observed planes as in the figure. /A 7=101^ 3Sj', OM-'i= 123° 3i' ; c:b:d= 1-596T : 1-2247 : 1. 0^ l-i - 117° 2', i-% A 1-2 = 143° 64', 1-2 A 1-2, adj., = 141° 48', ?'-iA'i-f = 118° 33'. Twins: twinning-plaue i-l^ common. Also massive. H. = 6-6-5. G.=7-8. Lustre nearly pure metallic, Bomewhat adamantine. Color iron-black. Streak red- dish-brown to black. Opaque. Brittle. IT Comp., Var. — A tantalate either (1) of iron, or (2) of iron and manganese, or (3) a stanno- tantalate of these two bases. Formula Fe(Mn)Ta:Oo. Sn is also often present (as FeSnOs. according to Ram- melsberg , and some of the tantalum is often replaced by columbium. Analysis. Ramm., Tamraela (G.=7-384), Ta,05 76-34, Cb.Os 7-54, SnOi 0-70.FeO 13-90, MnO 1-42=99 -90. Other varieties contain much more Cb.O^, the kinds shade into one another. Pyr. etc. — BE. unaltered. Witli borax slowly dissolved, yielding an iron glass, which, ali a certain xioint of saturation, gives, when treated in R.F. and subsequently tlamed, a gray- ish-white bead; if completely saturated bocm-nes of itself rloudv on cooling. With salt of pho.sphorus dissolves slowly, giving an iron glass, which in R.F. , if free from tungsten, is pale yellow on cooling ; treated with tin on charcoal it becomes green. If tungsten is present the bead is dark red, and is unchanged in color when treated with tin on charcoal. With soda and nitre gives a greenish-blue manganese reaction. On charcoal, with soda and suffi- oient borax to dissolve the iron, gives in R.F. metallic tin. Decomposed on fusion with 360 DESCKIPTIVE MmERAT.OGY» potaesiam bisulphate in the platinum spoon, and gives on treatment with dilute hydrochlorfo acid a yellow solution and a heavy white powder, which, on addition of metallic zinc, assumes u Bmalt-blue color ; on dilution with water the blue color soon disappears (v. Kobell). Obs. — Tantahte is confined mostly to albite or oligoclase granite, and is usually associated with berj'l. Occurs in Finland, at several places ; in Sweden, in Fahlun, at Broddbo and Finbo ; in France, at Chanteloube near Limoges, in pegmatite ; in North Carolina. Named Taiitalite by Ekeberg. from the mythic Tantalus, in playful allusion to the diflScul- ties (tantalizing) he encountered in his attempts to make a solution of the Finland mineral in acids. \J COLUMBITE.* NiobiLe. FerroUmenite. Ortliorhombic. /A /= 101° 26', O M-l = 134° 53^' ; c\h'.&^ 1-0038 : 1-2225 : 1. 6> A 14 = 140° 36', 6> A 1-S = 138° 2''6', i-l A 1-8 = 104° 30', 1-g A 1-5, adj., = 151°, U A e-3, ov. i-%, = 135° 40', i-1 A ^-2, ov. i-\ = 135° 30'. Twins : twinning-plaiie 2-1 Cleavage : i-l and i-i, the former most distinct. Occurs also rarely massive. 661 ^63 663 Haddam. Middletown, Conn. Greenland. ri. = 6. G. = 5*4-6'5. Lustre submetallic ; a little sliining. Color iron- black, brovrnish-black, grajisli-black ; of leu iridescent. Sti-eak dark red to black. Opaque. Fracture subconchoidal, unQven. Brittle. \/>J^ , - K J Comp., Var. — FeCb2(Tao)06, with some manganese replacinar part of the iron. The ratio of Cb : Ta generally — 3 : 1 (Bodenmais, Haddam), sometimes 4 : 1, 8 : 1, 10 : 1, etc.; in the Greenland columbite the Ta-Os is almost entireljf absent. Analyses, Blomstrand, (1) Haddam ^G.=:6 15), (2) Greenland (G.=5 395). Cb,06 Ta.Os WO3 SDO2 ZrOi FeO WnO HO (1) 51-53 28 05 0-76 0-34 0-34 13-54 4 97 016=10019 (a) 77-97 0-13 0-73 13 17-33 3 51 — = 99-80 Pyr., etc. — Like tantalite. Von Kobell states that when decomposed by fusion with caustic potash, and treated with hydrochloric and snlphuric acids, it gives, on the addition of zinc, a blue color much more lasting than with tantalite ; and the variety dumite, when similarly treated, gives, on boiling with tin-foil, and dilution with its volume of water, n sapphire-blue fluid, while, with tantalite and ordinary columbite, the metallic acid remains undissolved. The variety from Haddam, Ct., is partially decomposed when the powdered mineral is evaporated to dryness with concentrated sulphuric acid, its color is changed to white, light gray, or yellow, and when boiled with hydrociiloric acid and metallip zinc it gives a beautiful blue. The remarkably pure and unaltered columbite from Arksut-fiord in Green- land is also j)art.ially decomposed by sulphuric acid, and the product gives the reaction test with zinc, as above. Obs. — Occurs at Rabenstein, Bavaria; at Tirschenreuth. Bavaria ; at Tammela in Finland ; at Chanteloube, near Limoges ; near Miask in the Hmen Mts. ; at Hermanskjir, near Bjorskar, in Finlaad ; in Greenland, at Evigtok. OXYGEN COMPOUNDS. — TANTALATE8, C0LUMBATE8. 361 jii the United States, at Haddam, in. a granite vein, and near TVliddletown, Conn. ; at Chesterfield, Mass. ; Standish, Me. ; Acworth, N. H. ; also Beverly, Mass. ; Northfield, Mass, ; Plymouth, N. H. ; Greenfield, N. Y. The Connecticut crystals are usually rather fragUe from partial change ; while those of Greenland and of Maine are very firm and hard. Hekmannolite (Shepard). — From the columbite locality at Haddam, Ct. , and a variety of columbite due tc alteration. G. =5 85. Supposed by Hermann to contain " ilmenium " pent oxide (II.O5). Tapiolite.— Tetr.igonal. «} = -G4G4 (rutile «=-6442). FeTa2(Cb3)Oo, with Ta : Cb=4 : 1. Tammela, Finland. Hjelmite. — A stanno-tantalate of iron, uranium and yttrium. Massive. Color black. Near Fahlun, Sweden. YTTROTANTALITE. Black YttrotantaUte. Orthorhombic. /A 7= 123° 10' ; (9 A 2-1 = 103° 2Q';c:b:d= 2-0934 : 1*8482 : 1. Crystals often tabular parallel to i-i. qq^ Also massive; amorphous. H. = 5-5'5, G.=^5-4r-5 9. Lustre submetallic to vitreous aud greasy. Color black, browu. Streak gray to colorless. Opaque to subtrauslucent.- Frac- ture small eonchoidal to granular. 12 /2 Ytterby. Comp. — Mostly JlQ(Ta,Cb)..07, with two equivalents of water, perhaps from alteration ; R=:Fe : Ca : Y(Er,Ce)=:;l : 2 : 4. Con- taining also WO3 and SnOo. Analysis (Ramm. ), Ytterby. TaoOs 46-25, Cb.,05 13 ;}2, SnO, 1-12, WO3 2 36, UC 1-61,Y0 10 ■52, ErO 6-71, FeO 8-80, CeO 222, Ca 5-73, H,0 6 31=98 95. Pyr., etc. — In the closed tube yields water and turns yellow. On intense ignition becomes white. B.B. infusible. With salt of phosphorus dissolves with at first a separation of a white sl 4-78, CeO 3-17, FeO 1-38, H,0 203 =99-68. Obs. — Occurs at Jolster in Norway ; near Tvedestrand ; at Alve, island of Tiomoen, neat Arendal ; at Moretjiir, near Naskilen. Named by Scheerer from eii^evos, a stranger, in allusion to the rarity of its occurrence. iEsciiYNiTK.— Orthorhombic. H. =5-6. G. =4-9-5 14. Lustre submetallic to resinous, nearly dull. Color nearly black. Streak gray. Fracture small subconchoidal. Analysis, Ramm., Cb.Os 28 81, TiOo 2204, SnOo 018, ThO, 15-75, Fe0 317, CeO 18-4il. LaO(DiO) 5-60, YO 1-12, CaO 2-75, H,0 1 •07=99-58. In feldspar with mica and zircon. Miask in the Urals. POLYMIGNITE. — Orthorhombic. In slender crystals. H =6-5. G. = 4-77-4-85. Lustre brilliant. Color black. Streak dark brown. Fracture perfect couchoidal Composition doubtful. Fredericksviirn, Norway. Perhaps identical with geschynite (Frankenheim). PoLYCRASE. — Orthorhombic. H. =5-5. G. =5 09-5-12. Lustre bright. Color black. Streak grayish-brown. Fracture conchoidal. Analysis, Ramm., CbjOs 20-35, TaOs 400, TiO, 26-59, YO 23 32, FeO 2-72, CeO 2 61, UO, 7 70 H.O 4 02=98-84. In crystals in granite at Hitteroe, Norway. Mengite. — Occurs in short prisms. H. =5-5 5. G. =5-48. Color iron-black. Containe zirconium, iron, titanium. In granite veins in the Ilmen Mts. EUTUEREORDITE. — Doubtf ul ; contains titanium, cerium, etc. Rutherford Co., N. G FERGUSONITE.* Yellow Yttrotantalite. Tyrite. Bragite. Tetragonal, hemiliedral. O M-i - 124° 20' ; c = 1-464. Cleavage : in distinct traces. OXYGEN COMPOUNDS. TANTALATES, C0LUMBATE8. 363 H.=5-5-6. G.=5-S38, Allen ; 5-800, Turner. Lustre externallj dull, on the fracture brilliantly vitreous and submetallic. Color brownish-black; in thin scales pale liver-brown. Streak pale brown. Subtrauslucent — opaque. Frac- ture imperfect conchoidal. Comp. — According to Rammelsbersr, essentially R3(Cb,Ta)o08. Analysis, Ramm., Greenland, Cb.Os 44 45. TaoO.s "GSO. SnO^ 047, WO3 015, YO 24-87.Er0 9vsi, CeOT-63 (563 LaO.DiO), UO2 2-58, FeO 0-74, CaO 0-61, H,0 1 -49-99 10. The amount of water varies from 1-49-7 p. c, and is regarded by Ramm elsberg as arising from alteration. Obs. — Fergusonite occurs near Cape Farewell in Greenland, dis- seminated in quartz. Also found at Ytterby. Sweden ; in SOesia. Bragite is from Helle, Alve, and elsewhere in Norway. Tyiite is associated with euxenite at Hampemyr on the island of Tromoe, and Helle on the mainland ; at Nasskul, about ten miles east of Arendal. KocHELiTE. — Near fergusonite. In yellow square-octahedrons and crusts in granite. Kochelwiesen, near Schreiberhau, Silesia. Adelpholite. — A columbate of iron and manganese, containing 41-8 p. c. of metallic acids, and 9' 7 p. c. of water. Tetragonal. H. =3*5-4 '5. 6. =3-8. Tammcla, Finland. A.. 364 DRSCEIPTrVE MINEEALOGT. 3. PHOSPHATES, AESENATES, VANADATES, ETO. Anh\t)kous Phosphates, Arsenates, etc, (?-./JX^ ' XENOTIME. Ytterspath, Germ. ' Tetragonal. 0M = 138^ 45' ; c = 0-6201. 1 A 1, pyrara., = 124° 26' ; basal, = 82° 30'. Cleavage : 7, perfect. H.=4-5. G.=4-45-4-56. Lusti-e resinous. Color yellowish-brown, reddish-brown, hair-bi'Own, flesh-red, grayisli-M'hite, pale yellow ; streak pale brown, yellowish, or reddish. Opaque. Fracture uneven and splintery. Comp. — Y3Pii08=Phosphorus pentoxide (PjOs) 37 "87, yttria 6213=100. Pyr., etc. — B.B. infusible. When moistened with sulphuric acid colors the flame bluish-green. Difficultly soluble in salt of phosphorus. Insoluble in acids. Obs. — From a granite vein at Hitteroe ; at Ytterby, Sweden ; St. Gothard ; Binnenthal. In the U. S., in the gold washings of Clarksville, Georgia ; in McDowell Co., N. C; in the diamond sands of Bahia, Brazil. The wiserine of Kenngott has been shown by Klein to be octahedrite (vide p. 255). Cryptolite {Phosphocerite). — CesP^Os (with some Di), like monazite. Occurs in minute grains imbedded in apatite at Arendal ; Siberia. Apatite Grouj). t/ APATITE.^ Hexagonal ; often hemihedral. M = 139° 41' 38", Kokscharof ; c = 0*734603. (? A 2-2 =• 124° 14^'. Cleavage : ^>, imperfect ;/, more so. Also 670 St. Gothard. globular and reniform, with a fibrous or imperfectly columnar structure , also massive, sti ictiire granular. OXYGEN COMPOUNDS. — PHOSPHATES, ARSENATES, ETC. 365 H, =5, sometimes 4'5 when massive. G. = 2*92-3*25. Lustre vitreous, inclining to subresinous. Streak white. Color nsually sea-green, blnisli- green ; often violet-blue; sometimes white ; occasionally yellow, gray, red, flesh-red, and brown ; none bright. Transparent — opaque. A bhiisli opalescence sometimes in the direction of the vertical axis, especially in white varieties. Cross fracture conchoidal and uneven. Brittle. Var. — 1. Ordinary. Crystallized, or cleavable and granular massive, (a) The asparagus stone (originally fromMurcia, Spain) and moroxite (from Arendal) are ordinaiy apatite. The former was yellowish-green, as the name implies ; the lattqr was in greenish-blue and bluish crystals ; and the names have been used for apatite of the same shades from other places. 2. Fibrous, concretionary, stalactitic. The name Plwyfhorite was used by Kirwan for all apatite, but in his mind it especially included the fibrous concretionaiy and partly scaly mineral from Estremadura, Spain, and elsewhere. 3. Fluor-apatite, Uhlor-apatite. Apatite also varies as to the proportion of fluorine to chlorine, one of these elements sometimes replacing nearly or wholly the other. Comp. — The formulas of the two varieties are 3Ca3P...Oe + CaClo^Phosphorus pentoxide 40-92, lime 53-80. chlorine 6 -82 =101 '54 ; and SCasP.OB-l-CaFo = Phosphorus pentoxide 42 26, lime55o5, fluorine 377 = 101 08. .Sometimes both calcium chloride (CaClo), and calcium fluoride (CaFj), are present. Pyr.; etc. — B.B. in the forceps fuses with difficulty on the edges (F.=r4"5-5), coloring the flame reddish-yellow ; moistened with sulphuric acid and heated colors the flame pale bluish- green (phosphoric acid) ; some varieties react for chloriue with salt of phosphorus, when the bead has been previously saturated with copper oxide, while others give fluorine when fused with this salt in an open glass tube. Gives a phosphide with the sodium test. Dissolves in hydrochloric and nitric acid, yield?j3g with sulphuric acid a copious precipitate of calcium sulphate ; the dilute nitric acid solution gives with lend acetate a white precipi- tate, which B.B. on charcoal fuses, giving a globule with crystalline facets on cooling. Some varieties of apatite phosphoresce on heating. "DiS. — Characterized by its hexagonal form. Distinguished by its softnes? lirom beryl ; does not effervesce with acids like the carbonates ; unlike pyromorpbite, yields no lead B.B. Obs. — Apatite occurs in rocks of various kinds and ages, but is most common in naetamor- phic crystalline rocks, especially in granular limestone, granitic and many metalliferous veins, particularly tho.se of tin, in gneiss, syenite, hornblendic gneiss, mica schist, beds of iron ore; occasionally in serpentine, and in igneous or volcanic rocks ; sometimes in ordinary stratified limestone, beds of sandstone or shale of the Silurian, Carboniferous, Jurassic, Cretaceous, or Tertiary formations ; also in microscopic crj'stals in many igneous rocks, doleryte, etc. It has been observed as the petrifying material of wood. Among its prominent localities are Ehrenfriedersdorf in Saxony ; region of St. Gothard in Switzerland ; Mussa-Alp in Piedmont ; Untersulzbachthal and elsewhere in the Tyrol ; Bohemia ; in England, in Cornwall, with tin ores ; in Cumberland ; in Devonshire ; at Wheal Franco {fraiicolite), etc. The variety, moroxite, occurs at Arendal, Snarum, etc.. in Norway. The asj)(tragus stone or Spargelstein of Jumilla, in Murcia, Spain, is pale yellowish-green in color; and a variety from Zillerthal is wine-yellow. The phosplwrite, or massive radiated variety, is obtained abundantly near the junction of granite and argillyte, in Estremadura Spain ; at Scblackenwald in Bohemia ; at Krageroe, etc. In Mass., at Norwich; at Bolton, and elsewhere. In Neio Yoi'k, in St. Lawrence Co., in granular limestone; in Rossie; Sanford mine, Essex Co.; near Edenville, Orange Co. In New Jersey, near Suckasunny, ; Mt. Pleasant mine, near Mt. Teabo ; at Hurdstown, Sussex Co. In I'enn., at Leiperville, Delaware Co.; in Chester Co. In Delaware, at Dixon's quarry, Wilmington. In Canada, in North Elmsley, and passing into South Burgess ; similar in Ross ; at the foot of Calumet Falls ; at St. Roch, on the Achigan. Apatite was named by Werner from inraTaw, to deceive, older mineralogists having referred it to aquamarine, chrj^olite, amethyst, fluor, schorl, etc • ^« ' OsTEOi.iTK is massive impure altered apatite. The ordinary compact variety looks like lithographic stone of white to gray color. It also occurs earthy. Hanau. Guano. — Guano is bone-phosphate of calcium, or osteolite, mixed with the hydrous phos- phate, brushite, and generally with some carbonate of calcium, and often a little magnesia, alumina, iron, silica, gypsum, and other impurities. It often contains 9 or 10 p. c. of water. It is often granular or oolitic ; also compact through consolidation produced by infiltrating waters, in which case it is frequently lamellar in structure, and also occasionally stalagmitic and stalactitic. Its colors are usually grayish -white, yellowish and dark brown, and Bomo- times reddish, and the lustre of a siu-face of fracture earthy to resinous. 366 DESCRIPTIVE MFNERALOGT. PnosPHATic Nodules. Coprolites.— Phosphatic nodules occur in many foMsiliferoug rocks, which are probably in all cases of organic origin. They sometimes present a spiral or other interior structure, derived from the animal organization that afforded them, and in such cases their coprolitic origin is unquestionable. In other cases there is no structure to aid in deciding whether they are true coprolites or not. / PYROMORPHITE* Gninbleierz, Oerm. Ilexaojonal. riemihedral. ^ A 1 = 139^ 38' ; c = 0-7362. Cleavage: / and 1 in tia(;es. / conimonlv striated horizontally. Often globular, renifoi-m, and botryoidal or verrnciforni, with usually a subcolnranar struc- ture ; also fibrous, and granular. H.=3*5-4. G. = 6*5-7'l, mostly when without lime; 5-6'5, when con taining lime. Lustre resinous. Color green, yellow, and brown, of differ ent shades ; souietimes wax-yellow and fine orange-yellow ; also grayish white to milk-white. Streak white, sometimes yellowish. Subtransparent — subtranslucent. Fracture subconchoidal, uneven. Brittle. Comp.— Analogous to apatite, 3Pb3P208+PbCl3=Phosphoruspentoxide 15'71, lead oxide 82 27, chlorine 2-(j2=10060. Some varieties contain arsenic replacing part of the phosphorus, and others calcium replacing the lead. Pyr., etc. — In the closed tube gives a white sublimate of lead chloride. B.B. in the forceps fuses easily (F.=l'o), coloring the flame bluish-green ; on charcoal fuses without reduction to a globule, which on cooling assumes a crystalline polyhedral form, while the coal is coated white from the chloride, atd, nearer the assay, yellow from lead oxide. With soda on charcoal yields metallic lead ; some varieties contain arsenic, and give the odor of garlic in R.F. on charcoal. With salt of phosphorus, previously saturated with copper oxide, gives an azure- blue color to the flame when treated in O.F. (chlorine). Soluble in nitric acid. Diff. — Characterized by its high specific gravity, and pyrognostics. Obs. — Pyromorphite occurs principally in veins, and accompanies other ores of lead. Occurs in Saxony ; at Przibram, Mies, and Bleistadt, in Bohemia ; near Freiberg ; Clausthal in the Harz ; at Nassau ; Beresof in Siberia; Cornwall, Derbyshire, and Cumberland, in England; Leadhills in Scotland ; Wicklow, and elsewhere, Ireland. In the U. S. at Phenixville, Penn.; also in Maine, at Lubec and Lenox ; in Davidson Co. , N. C. The figures produced by etching (see p. 118) show that pyromorphite is hemihedral like apatite (Baumhauer). Named from irvp, fire, fiop(pri, form, alluding to the crystalline form the globule assumes on cooling. O MIMETITE.* Mimetesite. Hexagonal. 6> A 1 - 139° 58' ; c = 0-7276. Cleavage : 1, imperfect. II. = 3-5. G. = 7-0-7-25, mimetite; 5-4-5-5, hedy- ^"^ phane. Lustre resinous. Color pale yellow, jDassing yr^f\s. into brown; orange-yellow; white or colorless. Streak yy^ / /\\^ white or nearly so. Subtransparent — tianshicent. '^^^/. 8 , . ; \">n Comp.— Formula SPbsAsiOs-f-PbCU^Arsenic pentoxide 2320, 7| I \ K ^^^^ °^^^^ 74-96, chlorine 2*39=100-55. Generally part of the i I arsenic is replaced by phosphorus, and often the lead in part by cal- ••■■'v' •.-••".'. '■_iJ ciura. ^^^ ~ ' 2 J ^ ^ Pyr. etc.— In the closed tube like pyromorphite. B.B. fuses at 1, nJ \ 1/ X/^ and on charcoal gives in R.F. an arsenical odor, andiseas'ly reduced nA i//^ to metallic lead, coating the coal at first with lead chloride, and ^*|^ later with arsenous oxide and lead oxide. Gives the chlorine reac tions as under pyromorphite. Soluble in nitric acid. Obs. — Occurs at several of the mines in Cornwall ; in Cumberland. At St. Prix in France , kt Johanngeorgenstadt ; at Nerteehinsk, Siberia. At the Brookdale mine, Phenixville, Pa. OXYGEN COMPOUNDS. — PHOSPHATES, ARSENATES, ETC. 367 Mimetitc is hemihedral like apatite and pyromorphite, as shown by etohinj (Baumliauer), Named from ^lyurjr^jy, imitator, it closely resembling pyromorphite. Hepyphane. — A variety containing much calcium. Campyi.ite contains much lead pho» phate. l V iVANADINITE.* Jlexaijoiial. In simple hexagonal prisms, and prisms terminating in planes of tlie pyramids ; 1 A 1, over terminal edge, 142° 58', O Al = 140° 34', /a 1 = 130°. Usually in implanted globules or incrustations. H.='2-75-3. G. = 6-6623-7.23. Lustre of surface of fracture resinous. Color liglit brownish-yellow, straw-yellow, reddish-brown. Streak white or yellowish. Subtranslucent — opaque. Fracture uneven, or flat conchoidal. ferittle. Comp. — Formula 3Pb3V206+PbCl2 = Vanadium pentoxide 1936, lead oxide 7870 chlorine 3-50=100-56. Pyr., etc. — In the closed tube decrepitates and yields a faint white sublimate. B.B. fuses easily, and on charcoal to a black lustrous mass, which in R.P. yields metallic lead and a coat- ing of chloride of lead ; after completely oxidizing the lead in O. F the black residue give.s with salt of phosphorus an emerald-green bead in R.F., which becomes light yellow in O.F. Gives the chlorine reaction with the copper test. Decomposed by hydrochloric acid. If nitric acid be dropped on the crystals they become first deep red from the separation of vanadium pentoxide, and then yellow upon its solution. Obs. — This mineral was first discovered at Zimapan in Mexico, by Del Rio. Since obtained at Wanlockhead in Dumfriesshire ; also at Beresof in the Ural ; and near Kappel in Carinthia. DEcnfcNiTE. — PbVoOo (or with some Zn)=Vanadium pentoxide 45'1, lead oxide 54 9 = 100 Massive. Color deep red. Dahn, near Niederschlettenbach, Rhenish Bavaria. Freiberg in Breisgau (etisynchite). Descloizite.*— Pb,V;07=Vanad um pentoxide 291, lead oxide 70 9 = 100. Orthorhombic, South America. Wheatley Mine, Penn. PuciiEUiTE (^rewse^.— Orthorhombic, near brookite in form {Websky). Occurs in small implanted crystals. Color reddish-brown. In composition a bismuth vanadate, BiVOi = Vanadium pentoxide 28-3. bismuth oxide 71 7. Pucher mine, Schneeberg, Saxony. RoscoELlTE. — Occurs in thin micaceoua scales, arranged in stellate or fan-shaped groups. Color dark brownish-green. Soft. G.=2 9a8 (Genth) ; 2-902 (Roscoe). Analyses : 1. Ros- coe (Proc. Roy. Soc, May 10, 1876); 2. Genth (Am. J. Sci., July, 1870). CaO K.O NaoO H 61 8-56 0-82 1-08 moisture 2 27 = 101-62 tt. 7-59 Oiyign.4'96 0-85 gangue- 100-23 The above analyse."!, made upon material derived from the same source, differ widely, especially in regard to the state of oxidation of the vanadium. Genth makes it VeOn^: 2V2O:,, VjOt,. The formula given by Rosooo is 2.\1V.0„ 4- K,Si„Ojo + aq. Found in fi.ssuren in the porphyry, and in cavities in quartz at the gold mine at Granite Creek, El Dorado Co. , Cal. Named by Dr. Blake, who discovered xt. See further on p. 435. SiO, ?4t-25 V.O. 28-60 AIO3 1414 FeOa 113 MnOs 115 MgO 2-01 47-69 22 02VeOu 1410 1-67 FeO 2-00 368 DESCRtPTIVU MINERALOOT. WAGNERITB. ^ Monocliiiic. C = 71° 53', /A /= 95° 25', OaU = 144° 25', B. & M. ; c : b : d ^= 0'78654 : 1*045 : 1. Most of the prismatic planes deeply stiiated. Cleavage : /, and the orthodiagonal, imperfect ; O in traces. H.=5-5'5. G. =3*068, transparent crystal; 2'9S5, untransparent, Kam- melsberg. Lustre vitreous. iStreak white. Color vellow, of different shades ; often grayish. Translucent, Fracture uneven and splintery across the prism. Comp. — MgsPsOs+MgFarrPhosphorus pentoxide 43 8, magnesia 371, fluorine 11'7, mag- nesium 7*4 =100. Pyr., etc. — B.B. in the forceps fuses at 4 to a greenish-gray glass ; moistened with sulphu- ric acid colors the flame bluish-green. With borax reacts for iron. On fusion with soda effervesces, but is not completely dissolved ; gives a faint manganese reaction. Fused with salt of phosphorus in an open glass tube reacts for fluorine. Soluble in nitric and hydro- chloric acids. With sulphuric acid evolves fumes of fluohydric acid. Obs. — Occurs in the valley of Hollgraben, near Werfen, in Salzburg, Austria. Kjerulfine (v. Kobell). — Stands near wagnerite, but exact nature uncertain. In masses of a pale red color at Bamle, Norway. MONAZITE.* Monoclinic. <7= 76° 14', /A /=93° 10', 0M-\ = 0-94715 673 : 138° 8'; c'.h'.d 1-0265 : 1. Crys- tals usually fiatteued parallel to i-i. Cleavage : O very perfect, and brilliant. Twins: twin- ning plane O. II. = 5-5-5. G. = 4-9-5-26. Lusti'e inclining to resinous. Color brownish-hyacinth-red, (;l<)ve-bi'o\vn, or yellowish- brown. Subtransparent — sub- translucent. Ivather brittle. Oomp. — According to Rammelsberg, r)R3PoO„-t-Th,P,0„, where E=Ce,La, Di. Analysis by Kersten, Slatoust, P,0» 28-50, ThOi 17-95, SnOi 310, CeO 26 00, LaO 23-4C, MnO l-8(i, CaO 1-(J8, K.O and TiO, er. = 101-49. Pyr., etc. — B.B. infusible, turns gray, and when moistened with sulphuric acid colors the flame bluish-green. With borax gives a bead yellow while hot and colorless on cooling ; a saturated bead becomes enamel-white on flaming. Difficultly soluble in hydrochloric acid. Diff. — Its brilliant basal cleavage is a prominent character, distinguishing it from tita- nite. Obs.— Monazite occurs near Slatoust in the Ilraen Mtn. ; also in the Ural ; near Notero in Norway ; at Schreiberhau. In the United States, with sillimunite at Norwich ; at Yorktown, Westchester Co., N.Y.; near Crowder's Mountain, N. C. Named from /iomCw, to be aoUtdry, in allusion to its rare occunrence. TURNERITE. — Identical with monazite, as first suggested by Prof. J. D. Dana. Occurs in minute yellow to brown cry.stals, rarely twins, at Mt. Soiel. Dauphiny ; Santa Brigritta, Tavetsch ; Lercheltiny Alp, Binnenthal ; Laacher See (v. Rath.), c : b : (i= -021096 : 1 . 0'958444. C.=77° 18' (Trechmann). KORABFVEITE (liodomiivski) . — A cerium phosphate containing fluorine; near monazite Occurs in large crystalline masses of a yellowish "color at Korarfvct, near Fahlun, Sweden. . Nonvich Watertown, Ct. OXYCJEN COMPOUNDS. — PHOSPHATES, ARSENATES. ETC. 369 \J TRIPHYLITE.* Tripbyline. Orthorhombic. /A 1= 98°, OAi-l = 129° 33', Tschennak ; c:l:a~--- 1'211 : 1*1504: : 1. Faces of crystals usually uneven. Cleavage : O nearly perfect in unaltered crystals. Massive. IL=:5. G. = 3-54-3'6. Subresinous. Color green ish- giay ; also bluish ; often brownish-black externally. Streak grayish- white. Translucent in thin fragments. Comp.— RsP.Os, where R=Fe, Mn, (Ca) and Lij (Ko, Nan). Analysis byOesten, from Bodenmais. P-.Oi 4419, FeO 38-21. MnO 5 03, MgO 2-39, CaO 0-7G, Li.O 769, Na.O 0-74, K,0 004, SiO, 40=10005. The analyses vary much, owing to the impure material employed. Pyr., etc. — In the closed tube sometimes decrepitates, turns to a Norwich, dark colcv, and gives off traces of water. B.B. fuses at 15, coloring the rtame beautiful lithia-red in streaks, with a pale bluish-green on the exterior of the cone of tlanie. The coloration of the flame is best seen when the pulverized mineral, moistened with sulphuric acid, is treated on a loop of platinum wire. With borax gives an iron bead ; with soda a reaction for manganese. Soluble in hydrochloric acid. Obs. — Triphylite occurs at Rabenstein near Zwiesel in Bavaria ; also at Keityo in Finland ; Nor,vich, Mass. Named from rp/f, three-fold^ and ^uAtj, family, in allusion to its containing three phos- phates. TRIPLITE.* ZwieseUte. Orthorhombic. Imperfectly crystalline. Cleavage: unequal in three directions perpendicular to each other, one much the most distinct. II.=5-5-5. G. = 344-3'8. Lustre resinous, inclining to adamantine. Color brown or blackish-brown to almost black. Streak yellowish-gray or brown. Subtranslucent — opaque. Fracture small conchoidal. Comp.— RsPOs+RFn; R=Fe, Mu(Ca). Analysis, v. Kobell, Schlackenwald, P,06 33-85, Fe03 3-50, FeO 23-38, MnO 3000, CaO 220, MgO 3 05, F=810=104-08. Pyr., etc. — B.B. fuses easily at 1-5 to a black magnetic globule; moistened with sulphuric acid colors the flame bluish -green. With borax in 0. F. gives an amethystine colored glass (manganese); in R F. a strong reaction for iron. With soda reacts for .manganese. With sulphuric acid evolves fluohydric acid. Soluble in hydrochloric acid. Obs. — Found by AUuaud at Limoges in France, with apatite ; at Peilau in Silesia. Zwienelite^ a clove-brown variety, was found near Rabenstein, near Zwiesel in Bavaria, in quartz (G. =3-97, Fuchs). Sarcopside. — Near triplite. Valley of the Mlihlbach, Silesia. si AMBLYGONITE.* Triclinic. Cleavage : O perfect ; i-'i nearly perfect, angle between these cleavages 104^° ; also /imperfect. Usually massive, cleavable ; sometimes columnar. H. = 6. G.=:3-3'll. Lustre pearly on face of perfect cleavage {0)\ vitreous on t-i, less perfect cleavage-face ; on cross-fracture a little greasy. Color pale mountain or sea-green, white, grayish, brownish-white. Sub- transparent — translucent. Fracture uneven. Optical axes very divergent ; plane of axes nearly at i-ight angles to i-l', bisectrix of the acute angle negative, and parallel to the edge O Ji-%\ DesCl. 24 370 DESCRIPTIVE MENERALOGT. Oomp. — According to Rammelsberg, 2MPj08+3Li(Na)F. If Na : Li=l : 4, the foncula requires : Phosphorus pentoxide 4924, alumina 35 "58, lithia 6"24. soda 8-23, lluorme 9 '88 = 104 -17. Pyr., eto. — In the closed tube yields water, which at a high heat is acid and corrodes the glass. B. B. fuses easily at 2, with intumescence, and becomes opaque-white on cooling. Colors the flame jellowish-red with traces of green ; the Hebron variety gives an intense lithia-red ; moistened with sulphuric acid gives a bluish-green to the flame. With cobalt solution assumes a deep blue color (alumina). With borax and salt of phosphorus forms a transparent colorless glass. In fine powder dissolves easily in sulphuric acid, more slowly in hydrochloric. Diff.— Distinguished by its easy fusibility ; reaction for fluorine and lithia ; greasy lustre in the mass, etc. Obs. — Occurs at Chursdorf and Arnsdorf, near Penig in Saxony ; also at Arendal, Norway. In the U. States, in Maine, at Hebron (hebronite), imbedded in a coarse granite with lepidolite, albite, quartz, i-ed, green, and black tourmaline; also at Mt. Mica in Paris, 8 m. from Hebron, with tourmaline. The name is from a/ifiM.ig, blunt, and yow, angle. Hebronite. — The mineral from Hebron, Me. (see above), has been shown by DesCloizeaux to differ in optical character (v > />) from the Penig amblygonite. On this ground, as well as on account of a variation in the composition, it has been proposed (v. Kobell) to make it a new species. The same optical character and composition belong to the mineral from Montebras (called monttbrasite on the basis of an erroneous analysis). Analysis of hebronite, Pisani, P2O5 4G'G5, AlOi 3G-00, Li.O 9-75, HoO 4 20, F 5-22 = 101 82. Heudeuite. — Supposed to be an anhydrous aluminum-calcium phosphate, with fluorine. Color yellowish-white. Ehrenfriedersdorf. Ddrangite.— Monoclinic Cleavage prismatic (110^ 10). H.=5. G. =3937-4 -07. Color bright orange-red. Analysis, Hawes, Arsenic pentoxide 5311, alumina 1719, iron sesqui- oxide 923, manganese sesquioxide 208, soda 1306, lithia 0*65, fluorine 7'67=102-99. I Formula RnRAs^jOa (with one-ninth of the oxygen replaced by fluorine), or RASiOs-l-SRF. Here R=Na : Li=10 : 1 ; R=A1 : Fe : Mn=15 : 5 : 1. Other varieties, having a lighter color, have Al : Fe = 5 : 1. Occurs with cassiterite, near Durango, Mexico (Brush). Hebronite, Maine. Anhydrous Antimonates. MoNiMOMTE. — Mainly an an tim on ate of lead. YelltAv. G.=5'94. Paisberg, Sweden. Nadokite. — PbSb,04-i-PbCl2. In yellow translucent crystals. H. =3. G. =7 02. Djebel- Nador, province of Constantine, Algiers. ROMEITE. — An antimonate (or antimonite) of calcium. Occurs in groups of minute tetra- gonal crystals. Color yellow. St. Marcel, Piedmont. IlivoTiTi:. — Contains antimonic oxide, carbon dioxide, and copper. Amorphous. Coloi yellowish-green. Sien-a del Cadi. Stibioferrite. — Amorphous coating on stibnite, from Santa Clara Co. , Cal. Mixture (?). Hydrous Phosphates, Arsenates, etc. VT PHARMACOLITE. Monoclinic. /A 7= 111° 6', i-\ A *-2 = 109'' 26', 1 A 1 = 117° 24'. Cleavage: i-\ eminent. One of the faces 1 often obliterated by the exten sion of the other. Surfaces i-i and f 2 usually striated parallel to theii mutual interstjction. Rarely in crystals; commonly in delicate silky fibres or acicular ci-ystallizations, in stellated groups. Also botryoidal and stake- titic, and sonictiuics massive. OXYGEN COMPOUNDS. — PHOSPHATES, ARSENATES, ETC. 371 H.=--!2-2-5. G. = 2-6-Jr-"2-73. Lustre vitreous ; on /-Hncliuiug to pearlj Color white or g-ravisli ; frequently tinged red by arsenate of c A l-l = 144° 14' ; c 1-0446 : 1. Cleavage: / and 14 in traces. Sumetiines aci- cular. Also globular and reniforni, indistinctly fibrous, fibres straight and divergent, rarely promiscuous; also curved lamellar and granular. 1L = 3. G. = 4-l-4-4. Lustre adamantine — vitreous; of some fibrous varieties pearly. Color various shades of olive- green, passing into leek-, siskin-, pistachio-, and blackish- green ; also liver- and wood-brown ; sometimes straw-yellow and grayish-white. Streak olive-green — l)i-own. Subtrans- parent — opaque. Fracture, when observable, conchoidal — uneven. Brittle. J Comp. — Cu4As20j-|-aq=Cu3As20e+H2Cu02 (Ramm. ):^ Arsenic pentoxide 40-6(5, coppei oxide 5615, water 319 =100. Pyr., et=. — In the closed tube gives water. B.B. fuses at 2, coloring the flame bluish-green, aud on cooling the fused mass appears crystalline. B B. on charcoal fuses with deflagration, gives off arsenical fumes, and yields a metallic arsenide, which, with soda yields a globule of copper. With the fluxes reacts for copper. Soluble in nitric acid. Obs. — The crystallized varieties occur in many of the Cornwall mines ; near Tavistock in Devonshire ; also at Alston Moor in Cumberland ; at Camsdorf and Saalfeld in Thuringia ; the Tyrol ; the Banat ; Siberia ; Chili ; and other plades. Ad.\mite — ZnaASiOe-i-H.ZnO.^Arsenic pentoxide 402, zinc oxide 56-7, water 31=100. Color yellow. Chanarcillo, Chili ; Cap Garonne. Taqilite — CujP^Og-i-Saq (=Cu3P;Os-i-HjCuOj+2aq). Color emerald-green. Nischne- Tagilsk. IsoCLASiTE. CajP-.Og-l-oaq (=Ca3P208-i-H3Ca02-f-4aq). Colorless to snow-white. Joachimsthal. EuCHKOirK. — Cua.^SjOs-fHjCuOi-f 6aq (Ramm. )= Arsenic pentoxide 34-1, copper oxide 47-2. water 18 7=100. Color emerald-green. Libethen, Hungary. CnroKOTiLE. — Cu: As,;0a + 6aq. In capillary crystals. Also fibrous ; massive. Color apple- green. In quartz at Schneeberg and Ziunwall ; Thuringia; Chili (F/'e/icei). VeSzeltite (Schrdiif). — A hydrous copper phosphate ; composition 4Cu3P20g-l-5aq. Tri clinic. Occurs in crystalline crusts on a gamet-rock at Morawioza in the Banat. 374 DESCRIPnVE mineralogt. LIROCONITE. Linsenerz, Oerm. MonocHnic. IaI=7^° 21', DesCl. (7=88° 33'. Cleavage lateral, )>ut obtained with difficulty. Rarely granular. ri. = 2-2*5. G. = 2-8S-2*98. Lnsti-e vitreous, iniilining to resinous. Color and streak sky-bine — verdigris-green. Fracture imperfectly ''on- choidal, uneven. Imperfectly sectile. Comp.— Formula Cu3(Al) Asi(P,)08-l-H6(Cu3.Al)06 -l-9aq, with Cua : M=3 : S, and As: P=l : 4. This requires arsenic pentoxide 23 "1, phosphorus pentoxide 3 6, copper oxide 35 "9; alumina 10"3, water 27"1=100. Pyr., etc. — In the closed tube gives much water and turns olive-green. B.B. cracks open, out does not decrepitate ; fuses less readily than olivenite to a dark gray slag ; on charcoal oracks open, deflagrates, and gives reactions like olivenite. Soluble in nitric acid. Obs. — With various ores of copper, pyrite, and quartz, at Wheal Gorland, Wheal Muttrell, etc., in Cornwall ; also in minute crystals at Herrengrvind iu Hungary ; and in Voigtland. PSKUDOMALACHITE PhospJiochnlcUe. — CucP.Oi , +3aq = Cu3P.O,+3HjCuO. = PcOa 21 1, CuO 70-9, H,0 8-0=100. Trlclinic (Schrauf). G.=4-34. Color emerald-green. Related sub-species: Ehlite (P^rmfte), CusPjOs-f 2H,CuOj + aq (Ramm. ) ; DinvDUiTE, Cu3P2064- 2H2CUO2. Ehl, near Liuz, on the Rhine ; Libethen, Hungary ; Nischne Tagilsk ; Cornwall. Erinite. — Cu3Aso08-t-2H2CuO... In mammillated crystalline groups. Colorgreen. Corn- wall. CoRNWALLiTE. — Cu6A8,Oio+3aq (=Cu3A8,08-l-2H.>Cu02 + aq). Amorphous. Colorgreen. Cornwall [Church). PsiTTAClNlTE. — Occurs in thin crypto-crystalline coatings, sometimes having a botryoidal structure ; also pulverulent. Color siskin green to olive-green. Formula 2R3V..08-f-3HoCuOa -f 6aq, with R=Pb : Cu = 3 : 1. This requires : Vanadium pentoxide 1932, lead oxide 53'15, copper oxide 18'9o, water 8-58=100. Found at the gold mines in Silver Star District, Mon- tana (Genth. Am. J. Sci. , III., xii., 35, 187(3). MoTTilAMiTE. — Occurs as a thin crystalline incrustation, which is sometimes velvety, con- sisting of minute crj'stals ; more generally compact H. =3. G. =5'894. Color black by reflected light, in thiu particles yellowish, translucent (crystals) ; purplish-brown, opaque, (compact). Formula (Pb,Cu)3V-.:Oe + 2H.2(Pb,Cu)0:, which requires vanadium pentoxide 18'74, copper oxide 2039, lead oxide 57'18, water 3'G9=100. Related to dihydrite and **rinite. Found in Keiiper sandstone at Alderley Edge and Mottram St. Andrew's, in Cheshire, England (Roscoe, Proc. Roy. See, xxv., Ill,, 1876). VOLBORTHITE. — R4V209-i-aq, with R=Ca : Cu=2 : 3 (or 3 : 7), Ramm. From the Urala Kalk-volborthit {Germ.), Friedrichsrode, contains calcium. CLINOCLASITE. Strahlerz. Oerm. Monoclinic. 0= 80° 30', I A I, front, =M°. Cleavage : basal, highly perfect. Also massive, fiemispherical, or reniform ; 681 structure radiated fibrous. ' H.=:2-5-3. G.=4-19-4'36. Lustre: O pearly; elsewhere vitreous to resinous. Color internallj' dai-k verdigris-green ; externally blackish-blue gi'een. Streak bluish-green. Subtranslucent. Not very brittle. Comp.— Cu3As20.-+-3H2Cu02=Arsenic pentoxide 30*2, conpei oxide 62-7, water 7 1=^100. Pyr., etc. — Same as for olivenite. Obs. — Occurs in Cornwall, with other ores of copper, at scvenj mines. Also found in the Erzgebirge ^i . 1/ Tyrolite (Kupferschaum). — A hydrous arsenate of copper (Cui As:Oio-l-«aq), containing al.so calcium carbonate (as an impurity ? ) Color pale apple-green. Libethen. Hungary ; Schneeberg, etc. OXYGEN COMPOUNDS. PHOSPHATES, AKSENATES, ETC. 375 CHALCOPnYLMTE (Copper mica ; Kupferglimmer, ffer/w.)-— CusAajOj-l-SHoCuOo + 7HoO=t Arsenic pentoxidi- 21 3, copper oxide 587, water 200=100. Copper miaes of Cornwall, Hungary ; Moldawa. \/: LAZULITE. Blauspath, Germ. Monoclinic. 0= 8S° 15', J A I = 91° SO', 6> A 14= 139^ 45', Prufer; c:h:d = 0-8G004 : 1-02G0 : 1. Twins: twiuning-plane i-i; also O. Cleav- age: lateral, indistinct. Also massive. 683 683 684 H. = 5-6. G. = 3"057, Fnchs. Lustre vitreous. Color azure blue ; com- monly a fine deep blue viewed along one axis, and a pale greenish-blno along anotlier. Streak white. Subtranslucent — opaque. Fracture uneven. Brittle. Comp.— RAlP;03+aq=AlP208VH2(Mg,Fe;OQ (Dana)= Phosphorus pentoxide 46-8, alu- mina 340, magnesia 13 2, water 6'0=100. Pyr., etc. — ^In the closed tube whitens and yields water. B.B. with cobalt solution the blue color of the mineral is restored. In the forceps whitens, cracks open, swells up, and without fusion falls to pieces, coloring the flame bluish- green. The green color is made more intense by moistening the assay with sulphuric acid. With the fluxes gives an iron glass ; with soda on charcoal an infusible mass. Unacted upon by acids, retaining perfectly its blue color. Diflf.— Characterized by its fine blue color; blue flame B.B. Obs. — Occurs near Werfen in Salzburg; in Gratz, near Vorau ; in Krieglach, in Styria; at Hochthiiligrat, at the Gomer glacier, in Switzerland ; in Horrsjoberg, Wermland ; Y/estaua, Sweden ; also at Tijuco in Minas Geraes. Brazil. Abundant at Crowder's Mt., Lincoln Co., N. C; and on Graves Mt. , Lincoln Co., Ga., 50 m. above Augusta. ^^ SCORODITE. I A 1=98° 2', 6> A 1-1 = 132° 20'; c Cleavage : *-2 imperfect, i-i and i-l in Ortliorhombic. 1-1511 : 1, Miller traces. H. = 3"5-4. G.=3'l-3*3. Lusti-e vitreous — snbadaman- tine and subresinous. Color pale leek-green or liver-brown. Streak wliite. Subtransparent — translucent. Fracture uneven. Comp. — FeA8208 4-4aq=Ar8enic pentoxide 49'8, iron sesquioxide 34-6, water 15-6=100. Pyr., etc. — In the closed tube yields neutral water and turns yellow. B.B fuses easily, coloring the flame blue. B.B. on charcoal gives arsenical fumes, and with soda a black magnetic scoria. With the fluxes reacts for iron. Soluble in hydrochloric acid. b:d = 1-0977 . 685 376 DESCRIPTIVE MINERALOGY. Obs. — Found at Schwarzenberg in Saxony ; at Nertschinsk. Siberia ; Dembach in Nassau ; in the Cornish mines ; at the Minas Geraes, in Brazil ; in Popayan ; at the gold mines of Vic- toria in Au. tralia. Occurs in minute crystals and druses, near Edenville, N. Y .: in Cabarraa Co., N. C. ^ WAVELLITE. Ortliorhombic. /A /= 126° 25', (9 A 1-i = 143° 23' ; c\l\&=^ 0-7431 : 1*4943 : 1. Cleavage : / rather perfect ; also brachydia' 686 gonal. Usnalh' in lieniispherical or globular concretions, having a radiated strnctnre. IT. = 3-25-4. G. = 2-316-2-337. Lustre vitreous, inclin- ing to pearly and resinous. Color white, 2~)assing into yel- low, green, gray, brown, and black. Streak white. Trans- lucent. Comp— AlsP^Ol9,12aq=2AlPo08 + HfiAI06+9fl,q=Phosphoruspentox- ide35"16, alumina3810, water 26 74=100 ; 1 to 2 p. c. fluorine is often present, replacing the oxygen. Pyr., etc. — In the closed tube gives off much water, the last portions of which react acid and color Brazilwood paper yellow (fluorine), and also etch the tube. B B. in the forceps swells up and splits frequently into fine aciculai particles, which are infusible, but color the flame pale green ; moistened with sulphuric acid the green becomes more intense. Gives a blue with cobalt solution. Some varieties react for iron and manganese with the fluxes. Heated with sulphuric acid gives off fumes of tluo- hydric acid, which etch glass. Soluble in hydrochloric acid, and also in caustic potash. Diff. — Distinguished from the zeoUtes and from gibbsite by its giving a phosphorus reac- tion; it dissolves in acid intlwut gelatinization. Obs. — Found near Barnstaple, Devonshire ; at Clonmel and Cork, Ireland ; in the Shiant Isles of Scotland ; at Zbirow in Bohemia; Zajecov in Bohemia; at Frankenberg and Langen- striegis, Saxony ; Diensberg, near Giessen, Hesse Darmstadt ; in a manganese mine in Wein- bach, near Weilburg, in Nassau ; at VUla Rica, Minas Geraes, Brazil. In the United States, at the slate quarries of York Co., Pa.; at Washington mine, Davidson Co., N C; at White Horse Station, Chester Co. , Pa ; Magnet Cove, Ark. ZEPnAROViCHiTH — Near wavellite. Composition AlPoOs + 6aq (or 5aq, Ramm.). Compact. Color greenish to grayish. Occurs in sandstone at Treuic, Bohemia. CcERULEOLACTiTE. — Crypto-crystalline. Color milk-white to light blue. Composition (Petersen) Al.qP^Oig + lOaq. Katzenellnbogen. Nassau. Also Chester Co., Penn. (Genth^ who regards the copper, 4 p. c, as belonging to the mineral.) ^ PHARMACOSIDERITE. Wiirfelerz, Germ. Isometric ; tetrahedral. Crystals modified cubes and tetrahedrons. Cleavage: cubic, imperfect. O sometimes striated parallel to its edge of intersection with plane 1 ; planes often curved. Rarely granular. H. = 2-5. Ct. = 2-9-3. Lustre adamantine to greasy, not very distinct Color olive-green, passing into yellowish-brown, bordering scnnetimes upon hyacinth-red and blackish-brown ; also passing into grass-green, emerald- green, and honey -yellow. Streak gi-een — brown, yellow, pale. Snbtians- parent — snbtranslucent. Hather sectile. Pyroelectric. Comp.— Fe4Asr,Oj7,15aq-3FeAs.208-|-H6FeOB -f 12HoO=Ar3enic pentoxide 43 13, iron ■esquiozide 4000, water 16-87=100. Pyr., etc. — Same as for scorodite. Obs.- -Formerly obtained at the mines of ANTieal Gorland, WTieal Unity, and Carharrack, in Cornwall ; now found at Burdle Gill in Cumberland ; in minute tetrahedral crystals a1 WhealJane ; also in Australia ; at St. Leouard in 7 ranee and at S^aneeberg and Schwar- cenbi'.ig in Saxony. OXYGEN COMPOUNDS. — PnoSPHATES, ABSENATES, ETO. 377 Named from (pipfxaKov, poiscm (in allusion to the arsenic present), and irlSripos, iron. Wuvfd- erz, of the Germans, means cube-ore. Rhagite {Weisbach). — Composition BiioAs40n6+9aq=2BiA804+3H3Bi03=Arsenic pent- oxide 15'6, bismuth oxide 78-9, water 55=100. Spherical crystalline aggregates. Coloi bright green. Schneeberg, Saxony. Plumbogummite. — Composition uncertain. Contains essentially alumina, lead, water, and phosphorus pentoxide. Huelgoet ; Cumberland ; Mine la Motte, Mo. CHILDRENITE.* Orthorhorabic. 7 A /= 111° 54', OM-l= 136° 26' ; c'.b:d = 0-9512 1-4798 : 1. Plane O sometimes wanting, and the form a double six- sided pyramid, made up of the planes 1, 24, with ^-^ small. Cleavage : i-i^ imperfect. H.=4'5-5. G. — 3-18-3-24. Lustre vitreous, inclining to resinous. Color yellowish-white and pale yellowish-brown, also brownish-black. Streak white, yellowish. Translucent. Fracture uneven. Comp. — Formula somewhat uncertain. Analysis: Rammelsberg, PoOs 28 92, AIO3 14-44, FeO 30-68, MnO 907. MgO 014, H.O 1698=100 -23. "Pyr-i etc. — lu the closed tube gives off neutral water. B.B. swells up into ramifications, and fuses on the edges to a black mass, coloring the flame pale green. Heated on charcoal turns black and becomes magnetic. With soda gives a reaction for manganese. With borax and salt of phosphorus reacts for iron and manganese. Soluble in hydrochloric acid. Obs. — Occurs near Tavistock ; also at Wheal Crebor, in Devonshire ; on slate at Crinnia mine in Cornwall. Hebron, Me. (f. 688.). TaRQUOlS. Callaite. Kallait, Kalait, Germ. Reniform, stalactitic or incrusting. Cleavage none. II. = 6. Gr.=:2-6-2-83. Lustre somewhat waxy, feel)le. Color sky-blue, bluish-green to apple-green. Streak white or greenish. Feebly subtrans* lucent — opaque. Fracture small conchoidal. Comp. — Hydrous aluminum phosphate, perhaps A]2p20ii-f6aq=Phospho:us pentoxide 32-6. alumina 46-9, water 20-5=100 Pyr., etc. — In the closed tube decrepitate.'^, yields water, and turns brown or black. B.B. in the forceps becomes brown and assumes a glassy appearance, but does not fuse ; colors the flame green; moistened with hydrochloric acid the color is at first blue (copper chloride). With the sodium test gives phosphuretted hydrogen. With borax and salt of phosphorus gives beads in 0. F. which are yellowish green while hot, and pure green on cooling. With salt of phosphorus and tin on charcoal gives an opaque red bead (copper). Soluble in hydrocldoric acid. Obs.— Occurs in clay slate in a mountainous district in Persia, not far from Nichabour. According to Agaphi, the only naturalist who has visited the locality, turquois occurs only in veins, which traverse the mountain in all directions. An impure variety is found in Silesia, 378 DKSCRIPTITJi; liirNERALOGT. and at Oelsnitz in Saxony. W. P. Blake refers here to a hard yello.\ ish- to bhush-green stcnc (which he identifies with the chakhihuitl of the Mexicans) from the mountains Los Cerilhis, 20 m. S. E. of Santa Fe. A pale green turquois occurs in the Columbus d'strict, Nevada. Turquois receives a good polish, and is highly esteemed as a gem. The Persian king is Baid to retain for his own use all the larger and finely tinted specimens. Peganite.— Composition tVLP-.O,, -h6aq = Phosphorus pentoxide ;n 1. alumina 31 "l, water 237 = 100. Striegis, Saxony. DUFREKITE.— Composition Fe.P.0u-t-3aq (FeP,0,,+H6FeOfl^ = Pho!=phorus pentoxida 27-5, iron sesquioxide 62-0, water 10-5=100. Anglar, Dept. of Haute Vieune ; Hirschberg, Westphalia ; Allentown, N. J. In deposits of nodules 1 to (j in. thick, in Kockbridge Co., Va Andrewsite. — In globular forms, having a radiated structure. H.=4. G. =3-475 Color dark green. Analysis, Flight. PjO^ 26-09, FeOj 44-64, rVlO^ 0-92, CuO 1086, FeO 7-11 MnO 0-60, CaO 09, SiO, 49, H^O 8-79=99-59. In a tin lode, West Phenix mine, near Liskeard, Cornwall. Chalcosideuite. — In bright green crystals (triclinic) on Andrewsite (see above). H = 4-5. G.=3]0.S. Analysis, Flight, P-.Oo 2993, As.^Os OOl. FeOa 42 81. i^lOa 4-45, CuO 8-14, H O 15-00. UOstr. =100-94. Also as a coating on dufrenite. Cornwall. Sayn, Westphalia. Henwoodite.— In globular forms, with a radiated stracture. H. =4-4-5. G.=2-67.' Color turquois-blue to bluish-green. B.B. infusible. Analysis. P-O^ 48-94, rVlO^ 18-24 FeOs 2-74, (JuO 7 10. CaO 54. H,0 1710. SiC, 1-37, loss 397 = 100. Occurs on limonite at the West Phenix mine, Cornwall [Collins, Min. Mag., 1, p. 11). Cacoxenite.— Supposed to be an iron wavellite. Composition Fe..,P..0,, + 12aq. lu ra- diated tufts. Color yellow. Hrbeck mine. Bohemia. ARSENiosiDEKiTK.^-Analysis by Church, As^Os 39 86, FeOa 35-75, CaO 15-53, MgO 018 KgO 0-47, H,0 7-87=9966. Formula (Ramm.) 2CasA8208+FeASiO, + 3HoFe06. Eo- maneche. Atelestite. — Essentially a bismuth arsenate. In minute yellow crystals at Schneeberg. ^J TORBERNITE. Chalcolite. Kupfer-Uranit, Oerm. Tetragonal. 6> A 14 = 134° 8' ; c = 1'03069. Forms square tables, with often replaced edges ; rarely snboc.tahedral. Cleav- age : basal liiglilj perfect, micaceous. Unknown massive or earthy. H. = 2-2-5. G.=3-4-3'6. Lustre of 6> pearly, of other faces subadamaiitine. Color emerald- and grass-green, and sometimes leek-, apple-, and sis- Cornwall, kin-green. Streak somewhat paler tlian the color Transparent— subtranslucent. Fractnre not ob- servable. Sectile. Laminae brittle and not flexible. Optically uniaxial ; double refraction negative. Comp.— Q. ratio for R : IT : P : 0=1 : 6 : 5 : 8 ; formula CutToP.>0,o-f 8aq=2(tJO.,^3p.>Oi 4-Cu3P.08-l-24aq. The formula requires: Phosphorus pentoxide 15*1, uranium tric^dde 61-2, copper oxide 8-4, water 153 = 100. Pyr., etc. — In the closed tube yields water. In the forceps fuses at 2 5 to a blackish mass, and color.i the flame green. With salt of phosphoru.s gives a green bead, which with tin on charcoal becomes on cooling opaque red (< opper). With soda on charcoal gives a globule of copper. Affords a phosphide with the sodium test. Soluble in nitric acid. Obs — Guimis Lake, Tincroft and Wheal Buller, near Redruth, and elsewhere in Com-,vall. Found also at Johanngeorgenstadt, Eibenstock, and Schneeberg, in Saxony ; in Bohemia, at Joachimsthal and Zinnwald ; in Belgium, at V'ielsalm. Both this species and the autunite have gone under the common name of ura»jY< / th* former also as Copper-uranUe^ the latter Lime-uranit4> v/ OXYGEN COMPOUNDS. PHOSPHATES, AE8ENATE8, ETO. 379 AUTUNTTE.* Uranit; Kalk-Urangliinmer, Kalk-Uranit, Oerm. Orthorhombic ; but form very nearly square, and crystals resembling closely those of torbernite. Cleava^^e : basal eminent, as in torbernite. H. = 2-'^*5. G.=:3"05-3*19. Lustre of 6^ pearly ; elsewhere snbadaman- tine. Color citron- to sulphur-yellow. Streak yellowish. Translucent. Optically biaxial, DesCl. Coinp.— Q. ratio f or R : U : P : H=l : 6 : 5 : 10. Formula CaXJoPiOi^ 4-lOaq, which may be written 2(UOo)3P2O8+Ca3P2Og+30aq. The formula requires : Phosphorus pentoxide 14 9, uranium trioxide (UOa) 60'4, lime 5'9, water 18-8=100. Pyr., etc. — Same as for torbernite, but no reaction for copper. Obs. — Occurs at Johanngeorgenstadt ; at Lake Onega, Wolf Island, Russia; near Limoges; near Autun ; formerly at South Basset, Wheal Edwards, and near St. Day, England. Occura sparingly at Middletown, Ct. ; also in minute crystals at Chesterfield, Mass. ; at Acworth, N. H. Trogerite. — Composition UsAs20i4 i-13aq=(U02)3As208 + 12aq. This requires : Arsenic pentoxide 17-(5, uranium trioxide (35 9, water 1G-5=:100. Monoclinic. In thin tabular crys- tals of a lemon-yellow color. Schneeberg, Saxony. Walpurgite.— Composition BiioU3As4034 + 12aq=(U02)3As.,Oe+2BiAs04 + 8H;iBi03. This requires: Arsenic pentoxide 11 9, bismuth oxide 000, uranium trioxide 224, water5'7=:100. Monoclinic. In thin scaly crystals. Color wax-yellow. Schneeberg, Saxony. URANOSriNlTB. — An arsenic autunite. Composition CaU2AS;:0i2-t-8aq=2(U0j)sAs.;0e-t- Ca3A820B+24aq=Arsenic pentoxide 229, uranium trioxide 57 "2, lime 5 'G, water 14 '8 = 100. Color green. Schneeberg, Saxony. Ukanosph^uite. Color yellow. Analysis, Winkler ; \J O3 50-88, BijOs 44-34, H,0 4-75. Schneeberg. Zeunerite. — According to Winkler, an arsenic chalcolite, with which it is isomorphous. Composition CuUQAsoOi2+8aq=2('U02)3As20e + Cu3As208+24aq=Arsenic pentoxide 22-3, nranium trioxide 5(3 0, copper oxide 7 7, water 14-0=100. Color bright green. Schneeberg, Zinnwald, Saxony ; Cornwall. PiTTiCiTE. — Iron-sinter. Composition uncertain, contains As^Oa, FeOj, SO3, H^O. DiA- •WCHITK is similar, but contains PaOs instead of AsaOs. Hydrous Antimonates. BraDHEiMlTE (Bleini6re). — Amorphous, reniform, or spheroidal ; also earthy or Incrustlng. H.=4. G. =4-60-4-76. Color white, gray, brownish, yellowish. Composition uncertain; aiialysis by Hermann : Sb.Os 31-71, PbO 61-83, HoO 6-4(3 = 100. Results from the decompo- sition of other antimonial ores. From Nertschinsk in Siberia ; Horhausen ; near Endellion in Cornwall, with jamesonite, from which it is derived. Nitrates. The nitrates are all soluble, and hence are rarely met with la aatufe. They lr.( lude ; Nitre, potassium nitrate (KNO3). Found generally in crusts on the surface of the soil, oil walls, rocks, etc. Also found in numerous caves in the Mississippi Valley. Soda Nitre, sodium nitrate (NaNO,). Tarapaca, Chili. NlTROCAT.ClTE, calcium nitfate (CaNaO,,). Occurs in silky efflorescences in linjestone Caverns. NlTROMAGNEstTE, magnesium nitrate (MgNjOo). Prom limestone cavea NlTBP- GliAUBERTi K, nitro -sulphate of sodium. Desert of Atacama, Chili 380 DESCRIPTIVE MINEEALOOT. 4. BORATES. \j SASSOUTE. Triclinic. 7 A 1' - 118° 30', 6> A /=r 95° 3', O A 2' = 80° .rr . b &K Twins: com position -face 0. Cleavage: basal very perfect Ibnully ir small scales, apparently six-sided tables, and also in stalactiti-; forms, com- posed of small scales. H. = l. G. = 1*4S. Lustre pearly. Color white, except when tinged yellow by sulphur; sometimes gray. Feel smooth and unctuous. Taste acidulous, and slightly saline and bitter. Oomp — H6B,06=Boroii trioxide (B.Oa) 5646, water 43-54=100. The native stalactitic salt contaius, mechanically mixed, various impurities, as sulphate of magfiesium and iron, sulphate of calcium, silica, etc. Pyr., etc. — In the closed tube gives water. B.B. on platinum wire fuses to a clear glass and tinges the tlame yellowish-green. Soluble in water and alcohol. Obs. — First detected in nature by HiJfer in the waters of the Tuscan lagoons of Monte Rotondo and Castelnuovo, and afterward in the solid state at Sasso by Mascagni. The hot vapors of the lagoons consist largely of it. Exists also in other natural waters, as at Wies- baden ; Aachen; Krankenheil near Folz ; Clear Lake in Lake Co., California; and it haa been detected in the waters of the ocean. Occurs also abundantly in the crater of VuJcano, one of the Lipari islands, forming a layer on sulphur and about the fumaroles, where it was discovered by Dr. Holland in 1813. SUSSEXITE (Brush). In fibrous seams or veins. H.=3. G.=3*42. Lustre silky to pearly. Color white, with a tinge of pink or yellow. Translucent. Comp.— R-B Os+aq, with R=Mn : Mg=4 : 3 = Boron trioxide 34-3, manganese protoxide 39-9. magnesia 16-0, water 8'0 = 100. Pyr., etc. — In the closed tube darkens in color and yields neutral water. If turmeric paper .8 moistened with this water and then with dilute hydrochloric acid it assumes a red color (boron). Fuses in the flame of a caudle, and B.B. inO.F. yields a black crystalline maea coloring the flame intensely yellowish-green. Reacts for manganese with the fluxes. Soluble in hydrochloric acid. Obs. — Found on Mine Hill. Franklin Furnace, Sussex Co., N. J.; associated witli franklin- ite. zincite, willemite, and other manganese and zinc minerals. SZAIDELYITE. — A hydrous magnesium borate, MgsBjOuH-Saq (or 2ai)« Occurs in aclculat crystals. Color white. Hungary. LuDWiGiTE (T^WienrtaA;).— Finely fibrous masses. H. =5. G.=3-007-4-016. Color black ish-green to black. Composition R4FeBoOio, with R=Fe : Mg=l : 5, or 1 : 3. For the latter the formul.i requires : Boron trioxide 16 6, iron sesquioxide 37 9, iron protoxide 17'1, toagnesia 28 4. Occurs in a crystalline limestone with magnetite at Morawicza in the Bauat, also altered to limonite. OXTGBW COMPOUNDS. — BORATES. 381 V BORACITE.* Isoraetrlc; tetrabedral. Cleavage: octahedral, in traces. Cubic facee Rometimes striated parallel to alternate pairs of edges, as in pvrlte. II. = 7, in crystals; 4*5, massive. G. = 2-974, Ilaidinger. Lustre vitre- ous, inclining to adamantine. Color white, inclining to gray, yellow, and green. Streak white. Sub- 690 transparent — translucent. Fracture concboidal, un- even. Pyroelecti-ic, and polar along the four octa- hedral axes. Comp MgiBieCl Oso = 2Mg3BfeOi6+MgCl2 == Boron trioxide G2 57, magnesia 31-28, chlorine 7 93 = 101 78. Pyr., etc. — The massive variety gives water in the closed tube. B.B. both varieties fuse at 2 with intumescence to a white crys- talline pearl, coloring the flame gi'een ; heated after moistening with cobalt solution assumes a deep pink color. Mixed with copper oxide and heated on char- coal colors the flame deep azure-blue (copper chloride). Soluble in hydrochloric acid. Altera very slowly on exposure, owing to the magnesium chloride present, which takes up water. Obs. — Observed in beds of anhydrite, gypsum, or salt. In crystals at Kalkberg and Schild- Btein in Liineberg, Hanover ; at Segeberg. near Kiel, in Holstein ; at Luueville, La Meurthe, France ; massive and crystallized at Stassfurt, Prussia. ^ BORAX. Tinkal of India. Monoclinic. 6'= 73° 25', /A 7=87°, A 2-1 = 132° W ; c:b:a^ G'4906 : 09095 : 1. Cleavage: i-i perfect,; /less so; i-l in traces. II.=2-2'5. G. = 1'716. Lustre vitreous — resinous; sometimes earthy. Color white ; sometimes grayish, bluish, or greenish. Streak white. Translucent — opaque. Fracture concboidal. Rather brittle. Taste sweet- ish-alkaline, feeble. Comp — Na2B4O,-l-10aq=2(NaBO2 + HBO.)-l-9aq=Boron trioxide 36-6, soda 16-2, water 47-2 Pyr., eto. — B. B. puffs up, and afterwards fuses to a transparent globule, called the glass of borax. Soluble in water, yielding a faintly alkaline solution. Boiling water dissolves double its weight of this salt. Obs. — Borax was originally brought from a salt lake in Thibet. It is announced by Dr. J. A. Veatch as existing in the waters of the sea along the Calif onaia coast, and in those of many of the mineral springs of California. Occurs in the mud of Borax Lake, near Clear Lake, Cal. Also found in Peru ; at Halberstadt m Transylvania ; in Ceylon. It occurs in solution in the mineral springs of Chambly, St. Ours, etc., Canada East. The waters of Borax Lake, California, contain, according to G. E. Moore, 535 '08 grains of crystallized borax to the gallon. V UIjEXITC Boronatrocalcite, Natronborocalcite. In rounded masses, loose in texture, consisting of fine fibres, which are acicular or capillary crystals. II. = 1. G.=:l-65, IN, Scotia, How. Lustre silky within. Color white. Tasteless. Comp.~NaCaB509+5aq=Boron trioxide 49 7, lime 15-9, soda SS, water 25G=100. Pyr., etc. — Yields water. B.B. fuses at 1 with intumescence to a clear blebby glass, cclor 382 DESCRIPTIVE MINER ALOOr. ing the flame deep yellow. Moistened with sulphuric acid the color of the fluu e is luoment* urily changed to deep green. Not soluble in cold water, and but little so in hot ; the solution alkaline in its reactions. Obs — Occurs in the dry plains of Iquique, Southern Peru ; in the province of Tarapaca (where it is called tiz A 1 = 115° 42' ; I A "l-t, top, =- Crystals iisu- as in figures ; sometimes prismatic : 1-2276 : 1 102° 17' ; 1-1 A l-^, top, = 74° 36 ally tabular in tbe direction of the different axes. Cleavacre basal rather perfect ; /sonievAdiat less so; i-l imperfect. Also in globular forms, fibrous or lamellar, crested ; coarsely laminated, lamina; convergent and often curved ; also granular ; colors sometimes banded, as in stalagmite. H. = 2'5-3"5. G. = 4-3-4*72. Lustre vitreous, inclining to resinous; sometimes pearly. Streak white. Color white; also inclining to yellow, gray, blue, red, or brown, dark brown. Transparent to translucent — opaque. Sometimes fetid, when rubbed. Optic-axial plane brachydiagonal. Comp. — BaS04 = Sulphux trioxide 34 3, baryta 65 "7 = 100. Strontium and sometimes cal- cium replace part of the barium ; also silica, clay, bituminous or carbonaceous substances are often present as impurities. Pyr., etc. — B.B. decrepitates and fuses at 3, coloring the flame yellowish-green ; the fused mass reacts alkaline with test paper. On charcoal reduced to a sulphide. With soda gives at first a clear pearl, but on continued blowing yields a hepatic mass, which spreads out and soaks into the coal. If a portion of this mass be removed, placed on a clean silver surface, and moistened, it gives a black spot of silver sulphide. Should the barite contain calcium sulphate, this will not be absorbed by the coal when treated in powder with soda. Insoluble in acids. Diflf. — Distinguishing characters : high specific gravity, higher than celestite or aragonite ; cleavage ; insolubility ; green coloration of the blowpipe flame. Obs. — Occurs commonly in connection with beds or veins of metallic ores, as part of th<' gangue of the ore. It is met with in secondarj' limestone, sometimes forming distinct veins. and often in crystals along with calcite and celestite. At Dufton, in Westmoreland. Eng 388 DESCRIPl'IVE MINERALOGY. land ; in Cornwall, near Liskeard, etc., in Cumberland and Lancashire, in Derbyshire, Staf fordshii'e, etc.; in Scotland, in Argj'leshire, at Strontian. Some of the most important European localities are at Felsjbauja and Kremnitz, at Freiberg, Marienberg, Clausthal, Przibram. and at Roya and Roure in Auvergne. In the U. S. , in Conn. , at Cheshire. In N. York, at Pillar Point ; at Scoharie ; in St. Lawrence Co.; at Fowler; at Hammond In Virgiiiiit. at Eldridge's gold mine in Buckingham Co.; near Lexington, in Rockbridge Co.; Fauquier Co. In Kentucky, near Paris ; in the AV. end of I. Royale, L. Superior, and on Spar Id., N. shore. In Canada, at Landsdo\vn. In fine crystals near Fort Wallace, New Mexico. The white varieties of barite are ground up and employed as a white paint, either alone or mixed with white lead. V OELESTITE. Ortborhombic. /A 7=104° 2' (103° 30'-] 04° 30'), 6>Al-i = 121° 19^' ; G:h;d= 1-6432 : 1-2S07 : 1. 6> Al = 115° 38', O A \-l = 127° 56', 1 A 1, mac, = 112° 35', 1 A 1, bracb., = 89° 26'. Cleavage : O perfect ; /distinct; «4 less distinct. Also fibrous and radiated; sometimes globu- lar ; occasionally granular. 702 703 L. Erie. H. =3-3-5. G.=:3-92-3-975. Lustre vitreous, sometimes inclining to pearly. Streak wbite. Color wbite, often faint bluisli, and sometimes red- disb. Transparent — snbtranslucent. Fracture imperfectly coiicboidal- nneven. Yery brittle. Tricbroism sometimes very distinct. Comp. — SrS04=Sulphur trioxide 43-6, strontia 56-4r=100. Wittstein finds that the blue color of the celestite of Jena is due to a trace of a phosphate of iron. Pyr., etc. — B.B. frequently decrepitates, fuses at 3 to a white pearl, coloring the flame strontia-red ; the fused mass reacts alkaline. On charcoal fuses, and in R.F. is converted into a difficultly fusible hepatic mass ; this treated with hydrochloric acid and alcohol gives an intensely red flame. With soda on charcoal reacts like barite. Insoluble in acids. Diff. — Does not effervesce with acids like the carbonates ; specific gravity lower than that of barite ; colors the blowpipe flame red. Obs. — Celestite is usually associated with limestone or sandstone. Occurs also in beds of gypsum, rock salt, and clay ; and with sulphur in some volcanic regions. Found in Sicily, at Girgenti and elsewhere ; at Bex in Switzerland, and Conil in Spain ; at Domburg, near Jena ; in the department of the Garonne, France ; in the Tyrol ; Retzbanya ; in rock salt, at Ischl, Austria. Found in the Trenton limestone about Lake Huron, parti cuarly on Strontian Island, and at Kingston in Canada ; Chaumont Bay, Scoharie, and Lockport, N. Y. ; also the Rossie lead mine ; at Bell's IVIills, Blair Co.. Penn. Named from caleatis, celestial^ in allusion to the faint shade of blue often presented by the mineral. Barytocelestite. — Celestite containing barium sulphate 26 p. c. (Griineri, 204 p. c. (Turner). l-< 14=74' 54A', .i-lA^-i = 100 35, on crystals from Imfeld in the Binnenthal (Neminar). Drummond I.. Lake Erie: Niirten, Hanover. OXYGEN COMPOUNDS. — SULPHATES, ETC. 389 1/ ANHYDRITJB. r Orthorhombic. /A /= 100° 30', 6> A 1-i = 127° 19' ; c : ^ : (X = 1-3122 : 1-2021 : 1. \-l A 1-i, top, = 85°. Cleavage : i-l very per- 704 feet ; i-l also perfect ; O somewhat less so. Also librous, ~7j lamellar, granular, and sometimes impalpable. The ^\^ lamellar aiid columnar varieties often curved or contorted. lI.=:3-3 5. G-. = 2-899-2-9S5. Lustre : i-^ and t-i some- N it'gj- 'y\ what pearly ; vitreous ; in uiassive varieties, vitreous ■S ^ T V inclining to pearly. Color white, sometimes a grayish, ' — bluish, or reddish tinge; also briiiLouid. Streak grayish- ^ (S;- — -^ — =p1 white. Fracture uneven ; of finely lamellar and tibroua ^ iV 1 ^^J varieties, si)lintery. Optic-axial plane parallel to /-i, or Stassfurt. plane of most perfect cleavage; bisectrix normal to 0\ Grail ich. Var.— (a) Crystallized ; cleavable in its three rectangular directions. (6) fibrous ; either parallel, or radiated, or plumose, (c) Fine granular, (rf) Sc.ily granular. Vulpi/ute is a scaly granular kin;i from Yulpino in Lombardy ; it is cut and polished for ornamental purposes. It does not ordinarily contain more silica than common anhydrite. A kind in contorted concre- tionary forms is the tripestone {Gekrosxlein). Comp.— CaS04=Sulphurtrioxide 58 8, Ume 41-2=100. Pyr., etc.— B.B. fuses at 3, coloring the tlame reddish-yellow, and yielding an enamel-like bead which reacts alkaline. On charcoal in R.F. reduced to a sulphide ; with soda does not fuse to a clear globule, and is not absorbed by the coal like barite ; it is, however, decomposed, and yields a mass which blackens silver ; with fluorite fuses to a clear pearl, which is enamel-white on cooling, and by long blowing swells up and becomes infusible. Soluble in hydrochloric acid. Diflf. — Characterized by its cleavage in three rectangular directions ; harder than gypsum ; does not effervesce with acids like tlie carbonates. Obs. — Occurs in rocks of various ages, especially in limestone strata, and often the same that contain ordinary gypsum, and al.so very commonly in beds of rock salt. Occurs neai Hall in Tyrol ; at Sulz on the Neckar, in Wiirtemberg ; Bleiberg in Caxinthia ; Liineberg, Hanover; Kapnik in Hungaiy; Ischl ; Aussee in Styria ; Berchtesgaden ; Stassfurt, in fine crystals. In the U. States, at Lockport, N. Y. In Nova Scotia. V ANGLE SITE. Blci vitriol, Germ. Orthorhombic. /A 7=103° 43^, 6>Al-i, = 121° 20^', Kokscharof; c'.b'.d= 1-64223 : 1-273634 : 1. Oh 14 = 127° 48' ; 6> A 1 = 115° 35^' ; l-^ A 1-i, top, = 75° 35^'. Crystals sometimes tabular ; often oblong pris- matic, and elongated in the direction of either of the axes (as seen in the figures). Cleavage: 7, O, but interrupted. The planes 7 and z-i often vertically striated, and ^-l horizontally. Also massive, granular, or hardly BO. Sometimes stalactitic. H. = 2-75-3. G.=:612-6-39. Lustre highly adamantine in some speci- mens, in others inclining to resinous and vitreous. Color white, tinged yellow, gray, green, and sometimes blue. Streak uncolored. Transparent )paque. Fractui-e conchoidal. Very brittle. Comp.—PbSO^^ Sulphur trioxide 26-4. lead oxide 73-6=100. Pyr., etc. — B B. decrepitates, fuses in the flame of a candle (F. =l-5). On charcoal in 0. F. fuses to a clear pearl, which on cooling becomes milk-white ; in R. F. is reduced with effer- vescence to metallic lead. With soda on charcoal in R.F. gives metallic lead, and the soda is absorbed by the coal ; -when the surface of the coal is removed and placed on bright eilvei and moistened with water It tarnishes the metal black. Difficultly soluble in nitric acid. 390 DESCRIPTIVE MINEKALOOT- DiflF. — Does not effervesce with acid like cerussite (lead carbonate) ; listinguiahed by blow- pipe bests from other resembling species. Siegen. Obs. — This ore of lead was first obser\-ed by Monnet as a result of the decomposition of galenite, and it is often found in its cavities. Occurs in crystals at Leadhills ; at Pary's mine in Anglesea ; also at Melanoweth in Cornwall ; in Derbyshire and in Cumberland : Clausthal, Zillerfeld, and Giepenbach in the Harz ; near Siegen in Prussia ; Schapbach in the Black Forest ; in Sardinia ; massive in Siberia. Andalusia, Alston Moor in Cumberland ; in Aus- tralia. In the U. S., in large crystals at Wheatley's mine, Phenixville, Pa. ; in Missouri lead mines ; at the lead mines of Southampton, Mass. ; at Rossie. N. Y. ; at the Walton gold mine, Louisa Co., Va. Compact in Arizona, and Cerro Gordo, Cal. Dreelite. — Rhombohedral. H.=3'5. G.=3-2-3-4. Color white. Composition given a« CaS04 + 3BaS04. Occurs in small crystals at Beaujeau, France; Badenweiler, Baden. DotiEROPHANlTE {Scacchi). — CujSOo. In minute crystals. Monoclinic. Color brown, Vesuvius. Hydroctanite {Scacchi). — Anhydrous copper sulphate, CuSOi. Color sky-blue. Very Boluble. Vesuvius. Aphthitalite, Arcanite. — KoS04=Potash54-l, sulphuric acid 45 "9=100. Vesuvius. Thenardite.— Sodium sulphate, NajSO*. Spain; Vesuvius. LEADHILLITE. Orthorhombic. /a/=103M6', 6> A 1-t = 120 °10'; c : ^ : <^ = 1-7205 : 1-2632 : 1, Hernihedral in 1 and some other planes ; hence monoclinic in aspect, or rhombohedi-al when in compound crystals. Cleavage : i-l ver;y perfect ; i-'i in traces. Twins, f. Y12, consistincr of three crystals ; twinning plane, 1-/ (see f. 298, p. 97) ; also parallel with /. OXYGEN COMPOUNDS. — SULPHATES. 391 H.=2'5. G. = 6-26-6-44. Lustre of t-ipearlj,otlier parts resinous, some- what adaniantiue. Color white, passing into yellow, green, 711 712 or gray. Streak uncolored. Transparent — translucent, Conchoidal fracture scarcely ohservable. Rather sectile. Comp. — Formerly accepted for- mula, PbS04-|-:^PbC0, = Lead sul- phate 27 i~), lead carbonate 72 -00 = 100. Recent investigations by Las- pevres (J. pr., Ch II., v., 470; vii. , 127; xiii., 370), and Hintze (Fogg. Ann., clii., loG), though not entirely accordant, give diif ereut results, both show the presence of some water. Laspeyres writes the formula empirically, PbisCuSiOsi-f 5HjO, and Hintze, PbjC4S20oi+2H20. Analyses: 1. Laspeyres; 2, Hintze: SOs CO., PbO H.,0 1. 8-14 808 81 -yi 1-87=100, Laspeyres. 2. 8-17 918 80-80 200=:10015, Hintze. Pyr., etc. — B.B. inturaesces, fuses at I'S, and turns yellow ; but white on cooling. Easily reduced on charcoal. With soda affords the reaction for sulphuric acid. EfiEervesces briskly in nitric acid, and leaves white lead sulphate undissolved. Obs. — This ore has been found at Leadhills with other ores of lead ; also in crystals at Red Gill, Cumberland, and near Taunton in Somersetshire ; at Iglesias, Sardinia (mnxite). Sus.\NNiTE. — Composition as for leadhillite, but form rhombohedral. Leadhills; Nert- schinsk, Siberia. CoNNELi-iTE. — Hexagonal. In slender needle-like blue crystals. Contains copper sulphate and copper chloride. Exact c mposition uncertain. Cornwall. CvLKDONTTB. — Monoclinic (.Sc/inf?//). H. =2-5-3. G. =0-4. Color bluish-green. RoSOj -haq (Flight), with R=Pb : Cu=7 : 3, or 5PbS04+3H,CuO..+2H,Pb02. This requires : Sulphuric trioxide 19-1, lead oxide 65 "2, copper oxide 114, water 43=100. Leadhills, Scot- land ; Red Gill ; Retzbanya ; Mine la Motte, Missouri. Lanarkite. — Monoclinic. H. =2-2-5. G. =()-3-6-4. Color pale yellow, or greenish- white. Transparent. Compo.sition as formerly accepted, PbS04 + PbC03. New analyses by Flight, and by Pisani, show the absence of both carbon dioxide and water ; composition accordingly Pb3S05=PbS04+PbO, which requires : Lead sulphate 57-6, lead oxide 424=100. Leadhills ; Siberia, etc. GLAUBERITE. Monoclinic. C = Q^° W , lAl=S3°2(y, 6> A 1-i = 136° 30' ; c:b:a -= 0-8154 : 0-8267 : 1. Cleavage : O perfect. II. = 2-5-3. G. = 2-64:-2-85. Lustre vitreous. Color pale yellow or gray; sometimes brick-red. Streak white. Fracture conchoidal ; brittle. Taste slightly saline. Comp.— NaoCaSaO„=Sulphur trioxide 57-6, lime 201, soda 22-3= 100. Pyr., etc. — B.B. decrepitates, turns white, and fuses at 15 to a white enamel, coloring the flame intensely yellow. On charcoal fuses in 0. F. to a clear bead ; in R. F. a portion is absorbed by the charcoal, leaving an infusibe hepatic residue. With .soda on charcoal gives the reaction for sulphur. Soluble in hydjochloric acid. In water it loses its transparency, is partially dissolved, leaving a residue of calcium Bulphate, and in a large excess this is completely dissolved. On long exposure absorbs moisture and falls to pieces. Obs. — In crystals in rock salt at Villa Rubia in New Castile ; also at Aussee in Upper Austria ; in Bavaria ; at the salt mines of Vic in France ; and at Borax Lake, CaUfomia ; Province of Tarapaca, Peru. 392 DESCRIPTIVE MINERALOOT. Hydrous Sulphates. MIRABII.ITE. Glauber Salt. \r Monoelinic. 6"= 72° 15', /a/= SG° 31', O Al-l = 130" 19'; c:b:,i = 1-1089 : 0-8962 : 1. Cleavage : i-i perfect. Usnallj in efflorescuiit crusts. II.= 1-5-2. G. = l-481. Lustre vitreous. Color white. Transparent — opaque. Taste cool, then feebly saline and bitter. Comp.— Na,SO4 + 10aq=Sulphur trioxide 248, soda 19-3, water 55-9=100. Pyr., etc. — In the closed tube rauch water ; gives an intense yellow to the flame. Very soluble in water ; the solution gives with barium salts the reaction for sulphuric acid. Falla to powder on exposure to the air. and becomes anhydrous. Obs. — Occurs at Isehl and Hallstadt ; also in Hungary ; Switzerland ; Italy; at Guipuzcoa in Spain, etc. ; at Kailua on Hawaii; at Windsor, Nova Scotia ; also near Sweetwater River, Rocky Mountains. Mascagnite, Boussinqaultite (cerbolite), Lecontite, and Goanovulite are hydrous Bulphates containing ammonium. ^ GYPSUM. Monoelinic. C= G6° 14', if the vertical prism / (see f. 710) correspond to the cleavage prism (second cleavage), and the basal plane O to the direction of the third cleavage. /A 7 =138° 28', 1 iAl-i = 128° 31' ; c:b:d- 0-9: 2-4135 : 1. Oa 1 = 125° 35', A 24=145° 41', 1 A 1 = 143° 42', 2-iA2-i=lll°42'. Cleavage: (1) i-l, or clinodiagonal, eminent, affording easily smooth pol- ished folia ; (2) /, imperfect, fibrous, and often appareut in iuterual rifts or linings, makiug with O (or the edge 2-i/2-i) the angles 6Q° 14', and 113" 46', corresponding to the obliquity of the fundamental prism ; (3) O, or basal, imperfect, but affording a nearly smooth surface. Twins: 1. Twin- ning-plane common (f. 717) ; also l-^, or edge 1/1, Simple crystals often with warped as well as curved surfaces. Also foliated massive ; lamellar Btellate; often granular massive; and sometimes nearly impalpable. OXYGEN COMPOUNDS. — bJLPHATES. 393 1J. = 1-5-2. G. = 2-314-2-328, when pure crystals. Lustre of i-i pearly and shining, other faces subvitreous. Massive varieties often glistening, sometimes dull earthy. Color nsnally white ; sometimes gray, liesh-red, lioney-yeHow, ochre-yellow, blue ; impure varieties often black, brown, red or reddish-brown. Streak white. Ti'ansparent — opaque. Var 1. Crystnllized. or Selenite ; either in distinct crystals or in broad folia, fhe folia Bometimes a yard across and transparent throughout. 2. Fibrous ; coarse or fine, {(t) Satin »par, when fine-fibrous a variety which has the pearly opalescence of moonstone ; {h) plumose, when radiately arranged. 3. Massive; Alabaster, a fiue-grained variety, either white oi delicately shaded ; sea ly- granular ; earthy ox rock-rjypsum, a dull-colored rock, often impurn with clay or calcium carbonate, and sometimes with anhydrite. Comp. — CaS04 + 2aq= Sulphur trioxide 4(3 i"), lime ;{2 (i, water 209 = 100. Pyr., etc. — In the closed tube gives off water and becomes opaque. Fuses at 2'0-3, color- ing the flame reddish-yellow. For other reactions, see Anhydrite, p. 389. Ignited at a temperature not exceeding 260' C. , it again combines with water when moistened, and becomes firmly solid. Soluble in hydrochloric acid, and also in 400 to 500 parts of water. Diff Characterized by its softness ; it does not eilervesce nor gelatinize with acids. Some varieties resemble heulandite, stilbite, talc, etc.; and in its fibrous forms it is like some calcite. Ob5. — Gypsum often forms extensive beds in connection with various stratified rocks, espe- cially limestone, and marlytes or clay beds. It occur.s occasionally in crystalline rocks. It is also a product of volcanoes ; produced by the decomposition of pyrite when lime is present ; and often about sulphur springs ; also deposited on the evaporation of sea-water and brines, in which it exists in solution. Fine specimens are found in the salt mines of Bex in Switzerland ; at Hall in the Tyrol ; in the sulphur mines of Sicily ; in the gj'psum formation near Ocana in Spain ; in the clay of Shotover Hill, near Oxford ; at Montmartre, near Paris. A noted locality of alabaster occurs at Castelino, 85 m. from Leghorn. In the U. S. this species occurs in extensive beds in N. York, Ohio, Illinois, Virginia, Tennessee, and Arkansas ; it is usually associated with salt springs. Also in Nova Scotia, Peru, etc. It is characteristic of the so-called triassic, or red beds, of the Rocky Mountain region ; also of the Cretaceous in the west, particularly of the clays of the Fort Pierre group, in which it occurs in the form of transparent plates. Handsome selenite and snowy gypsum occur in N. York, near Lockport ; also near Camil- las, Onondaga Co. In Maryland, on the St. Mary's, in clay. In Ohio, large transparent crystals have been found at Poland and Canfield, Trumbull Co. In Tenii., selenite and ala- baster in Davidson Co. In Kentucky, in Mammoth Cave, in the form of rosettes, etc. In N. Scotia, in Sussex, King's Co., large crystals, often containing much symmetrically dis- seminated sand (Mar.sh). Plaster of Paris (or gypsum which has been heated and ground up) is used for making moulds, taking casts of statues, medals, etc. ; for producing a hard finish on walls ; also in the manufacture of artificial r.iarble, as the scagliola tables of Leghorn, and in the glazing of. porcelain. / POLYHALITE. Monoclinic (?). A prism of 115°, with acute edges truncated. Usually in compact fibrous masses. 11. = 2-5-3. G. = 2-7689. Lustre resinous or slightly pearly. Streak red. Color fiesh- or brick-red, sometimes yellowish. Translucent— opaque Taste bitter and astringent, but very weak. Comp.— 2RS04+aq, where R=Ca : Mg : K. in the ratio 2:1:1; that is, K,MgCa,S40,, -I- 2aq= Calcium sulphate 45 '2, magnesium sulphate 19 9, potassium sulphate 2b 9, water 6 -Or: 100. Pyr,, etc. — In the closed tube gives water. B.B fuses at 1 '5. colors the flame yellow. On charcoal fuses to a reddish globule, which in R.F. becomes white, and on cooling has a saline hepatic taste ; with soda like glauberite. With fluor does not give a clear bend. Partially soluble in water, leaving a residue of calcium sulphate, which dissolves in a larga amount cl water 394 DESCETPTIVE MINERALOGY. Obs. — Occurs at the mines of Ischl, Ebensee, Aussee, Hallstfitt, and Hallein iu Ausiria, with common salt, gj'psum, and anhydrite ; at Berchtesgaden in Bavaria ; at Vic in Lorraine. The name Polyhalite is derived from iroAuj, many^ and oAs, salt, in allusion to the numbel of salts in the constitution of the mineral. Synoenite, «. Zefilmrovicli ; Kainszite. Ji'nnpf. — Near polyhalite. Composition RS04 + aq, \Aith R=Ca : Ko=l : 1, that is, K.2CaS,Otf+aq = Potassium sulphate 53 1, calcium sul' phate 41 4, water 5 -5 = 100. Monoclinic. Occurs in small tabular ciystals in cavities in balito at Ralusz, East Galicia. KlESERiTE.— MgS04+aq=Sulphur trioxide 580, magnesia 28-0, water 18 0=100. Sta-ss- furt. PiCROMERiTE is K»MgS208+6aq=Sulphur trioxide 39 "8, magnesia 9 9, potash 23 4, watfti 26-9=100. Vesuvius; Stassfurt. Bloedite. — Composition NaoMgS..08 + 4aq= Sulphur trioxide 47-9, magnesia 12-0, soda 18-6, water 21*5=100. Salt mines of Ischl ; also in the Andes. SiMONtlTE {TucheiiTiak) la identical. LmwEiTE.— 2Na2MgS208+5aq=Sulphur trioxide 52*1, magnesia 130, soda 202, watei 14-7=100. From IschL EPSOMITE. Epsom Salt. Bittersalz, Onrm. Orthorhombic, and generally hemiheclral in the octahedral modiiications. /A /= 90° 34', A l-l = 150° 2' ; c : b : d = 0-5766 : 1-01 : 1. 14 A 1-i, basal, = 59° 27', l-l A 1-i, basal, = 59° 56'. Cleavage : brachydiagonal, perfectt. Also in botryoidal masses and delicately librous crusts. 11. = 2-25. G.=l-751 ; 1*685, artificial salt. Lustre vitreous — earthy, Streak and color white. Transparent — translucent. Taste bitter and saline. Comp. — MgS04+7aq, when pure = Sulphur trioxide 32'5, magnesia 163, water 51-2=100. Pyr., etc. — Liquifies in its water of crystallization. Gives much water in the closed tube at a high temperature; the water is acid. B.B. on charcoal fuses at first, and finally yields an infusible alkaline mass, which, with cobalt solution, gives a pink color on ignition. Very soluble in water, and has a very bitter taste. Obs. — Common in mineral waters, and as a delicate fibrous or capillary efflorescence on rocks, in the galleries of mines, and elsewhere. In the former state it exists at Epsom, Eng- land, and at Sedlitz and Saidschutz in Bohemia. At Idria in Carniola it occurs in silky fibres, and is hence called hairsnlt by the workmen. Also obtained at the gypsum quarries of Mont- martre, near Paris ; in Aragon and Catalonia in Spain ; in Chili ; found at Vesu\'ius, etc. The floors of the limestone caves of Kentucky, Tennessee, and Indiana, are in many instances covered with epsomite, in minute crystals, mingled with the earth. In the Mam- moth Cave, Ky. , it adheres to the roof in loose masses like snowballs. Fauseritk. — A hydrous manganese-magnesium sulphate. Hungary. Copperas Group. OHALOANTHITE. Blue Vitriol. Kupfervitriol, Oerm. Triclinic. (9a/=109° 32', OhT = 127° 40', /a/' = 123° 10', OM ==125° 38', (9 A *-* = 120° 50', 0^i-^-lQ^° 27'. Cleavage: / imper- fect, /' very imperfect. Occurs also amorphous, stalactitic, reniform. II. = 2-5. G. = 2-213. Lustre vitreous. Color Berlin-blue to sky-blue, of different shades ; sometimes a little greenish. Streak uncolored. Sub- transparent — translucent. Taste metallic and nauseous. Somewhat brittle. Oomp.— CuSOi -f 5aq=Sulphur trioxide 321, copper oxide 31-8, water 36-1 = 100. Pyr., etc. — In the closed tube yields water, and at a higher temperature sulphuric acid. B.B. with soda on charcoal yields metallic copper. With the fluxes reacts for copper. Solu- ble in water; a drop of the solution placed on a surface of iron coats it with metallic copper. Obs. —Blue vitriol is found in waters issuing from mines, and in connection with rocks con- taining chalcopyrite, by the alteration of which it is formed. Some of its foreign localitiei OXYGEN COMPOUNDS. SULPHATES. 395 are the Rammelsberg mine, near Qoslar, in the Harz ; Fahlun in Sweden ; at Parys mine. Anglesey ; at various mines in Co. of Wicklow ; Rio Tinto mine, Spain. Found at the Hiwassee copper mine, and other mines, in Polk Co. , Tennessee ; at the Canton mine, Georgia ; at Copiapo, Chili, with styptiaite. When purified it is employed in dyeing operations, and in the printing of cotton and linen, and for various other purposes in the arts. It is manufactured mostly from old sheathing, copper trimmings, and reiinery scales. Other vitriols are : — Melanterite, iron vitriol ; Pisanite, iron-copper vitriol ; Goslar- fTE, zinc vitriol; Biebekite, cobalt vitriol ; Morenosite, nickel vitriol ; CUPROMAGNESITE, copper-magnesium vitriol (Vesuvius). These are all alike in containing 7 molecules of watel of crystallization. Alunogen (Haarsalz, Germ.). — AlS3Oi2+18aq=Sulphurtrioxide36"0, aluminal5"4, watei 48'6=:100. Taste like that of alum. Vesuvius; Konigsberg, Hungary. CoQUiMBiTE. — FeS30i2+9aq=Sulphur trioxide 43-7, iron sesquioxide 28-5, water 28'8= 100. Coquimbo, ChiU. Ettringite (Ze/manra).— Analysis, SOs 16-64, AIO3 7-76, CaO 27-27, HjO 45-82. In hexa- gonal needle-like crystals from the lava at Ettringen, Laacher See. Alum and Hahtrichite Groups. Here belong: Tschermigite, ammonium alum. KAi.rNiTE, potassium alum, or common alum. Mendozite, sodium alum. i/Pickeringite, magnesium alum. Apjohnite, man- ganese alum. Bosjemannite, mangano-magnesium alum. Halotrichite, iron alum. Also RCEMERITE, and Voltaite. OOPIAPITE. Hexagonal (?). Loose aggi'egation of crystalline scales, or granular massive, the scales rhombic or hexagonal tables. Cleavage : basal, perfect. In- crnsting. H. = l-5. G. = 2'14, Borcher. Lustre pearly. Color sulphur-yellow, citron-yellow. Translucent. Comp.-i'e^SsO,,! + 13aq; sFeSsO,^ -f HjE'eOe + 36HoO = Sulphur trioxide 41 '9, iron sesquioxide 33-5, water 24-5 = 100. Pyr., etc. — Yields water, and at a higher temperature sulphuric acid. On charcoal be- comes magnetic, and with soda afifords the reaction for sulphur. With the fluxes reactions for iron. In water insoluble. Obs — Common as a result of the decomposition of pyrite at the Rammelsberg mine, near Qoslar in the Harz, and elsewhere. This species is the yellow copperas long called misy, and it might well bear now the name Mi'^ylite. Raimondite. — Composition FeaSads+Yaq. FibroferriTE (stypticite). — Composition FeS.Oa + lOaq. Botryogen is red iron vitriol, exact composition uncertain. Fahlun, Sweden. Bartho- LOMiTE, West Indies, is related. Iiileite. — Fe S30i24-12aq. Occurs ae a yellow efflorescence )n gi-aphite from Mugxaa, Bohemia (Schrauf). ALUMINITE. Reniforra, massive ; impalpable. H.=l-2. G.=1'66. Lustre dull, earthy. Coloi' white. Opaqne. Fracture earthy. Adheres to the tongue ; meagre to the touch 396 DESCRIPnVE mineealog\ Comp — AlS06+9aq= Sulphur trioxide 23-2, alumina 29-8, water 47 0=100. Pyr., etc. — In the closed tube gives much water, which, at a high temperature, beoomei acid from the evolution of sulphurous and sulphuric oxides. B.B. infusible. With cobalt solution a fine blue color. With soda on charcoal a hepatic mass. Soluble in acids. Obs. — Occurs in connection with beds of clay in the Tertiary and Post- tertiary formatious. Found near Halle ; at Newhaven, Sussex ; Epernay, in Lunel Vieil, and Auteuil, in France / WEUTnEMANiTE.— rVlSOa + Saq. G.=2-80. Occurs near Chachapoyas, in Peru. ^ Alunite, Alaunstein, Germ. — Composition KnAl3S40oo + 6aq. Rhombohedral. Also massive, fibrous. Forms seams in trachyte and allied rocks. Tolfa, near Rome ; Tuscany; Hungary ; Mt. Dore, France, etc. LiiwiGiTE. — Same composition as alunite, but contains 3 parts more of water. Tabrze, Silesia. LINARTTE. Bleilasur, Kupferbleispath, Germ. Monoclinic. C= 77° 27' ; 7a /, over i-i, = 61° 36', 6) A 14 = 141° 5', c:J):d = 0-48134 : 0-5S19 : 1, Hesseiiberg. Twins: twinniiig-plane i-i coininon ; 6^A(?' = 154° 54'. Cleavage : i-i very perfect ; less so. lI. = 2-5. G. = 5.3-5'45. Lustre vitreous or ada- mantine. Color deep azure-blue. Streak pale blue. Translucent. Fracture conclioidal. Brittle. Comp.— PbCuSO5+aq=(Pb.Cu)SO4+H,(Pb,Cu)O,-Sulphurtrioxide20 0, leadoxide55-7, copper oxide 10 8, water 45 = 100. Pyr., etc. — In the closed tube yields water and loses its blue color. B.B. on charcoal fuses easily to a pearl, and in R.F. is reduced to a metallic, globule which by continued treatment coats the coal with lead oxide, and if fused boron trioxide is added yields a pure globule of copper. With soda gives the reaction for sulphur. Decomposed with nitric acid, leaving a white residue of lead sulphate. Obs. — Formerly found at Leadhills. Occurs at Roughten Gill, Red Gill, etc. , in Cumber- la ud ; near Schneeberg, rare; in Dillenburg; atRetzbanya; in Nertschinsk ; and near Beresof in the Ural ; and supposed formerly to be found at Linares in Spain, whence the name. BROCHANTITE. Monoclinic. C = 89° 27^'. 1^T^ 104° 6^', O M-l = 1.54° 12^'; c : b : d = 0-61983 : 1*28242 : 1. Sclirauf distinguishes four types of forms : I. Brochantite from Retzbanya (two vai'ieties), also from Cornwall and Russia, triclinic ; II. Warri)igto7iite from Cornwall, a third variety from Retzbanya, monoclinic (?) ; 111. Brochantite from Nischne-Tagilsk, mono- clinic — triclinic ; IV. Konigine from Russia, and a fourth variety from Retz- banya, monoclinic (or orthorhombic). Also in groups of acicular crystals and drusy crusts. Cleavage : t-\ very pei'f ect ; 1 in ti-accs. Also massive; reniform with a columnar structure. II. = 3-5-4. G. = 3-78-3-S7, Magnus ; 3-9069, G. Rose. Lustre vitreous; a little pearly on the cleavage-face. Color emerald-green, blackish green. Streak paler green. Transparent — translucent. Comp.— Cu^SO, -l-3H,0=CuS04 + 3H2Cu02=Sulphur trioxide 17-71, copper oxide 70 34, water 11 95=100. This formula belongs to type IV., above; the warrLngtonite corresponda more nearly to CuSOi+oH.CuOj-hHiO, and the existence of other varieties has been also assumed. Pyr., etc. — Yields water, and at a higher temperature sulphuric acid, in the closed tube, and becomes black. B.B. fuses, and on charcoal affords metallic copper. With soda give* the reaction for sulphuric acid. OXYGEN COMPOUNDS. — SULPHATES. 397 Cbs.— Occurs at Gumeschevsk and Nischne-Tagilsk in the Ural ; the Konigine (or Kdnigite] was from Gumeschevsk ; near Roug-hten Gill, in Cumberland ; in Cornwall (in part warring- tonite) ; at Retzbanya ; in Nassau ; at Krisuvig in Iceland (krisuvigite) ; in Mexico {biongnar- tine) ; in Chili, at Audacollo ; in Australia. Named after Brochant de Villiers. Langite. — CuS04-i-2H;CuO, + 2aq. In crystals and concretionary crusts of a blue color. G. =;!'•'). Cornwall. CvANOTRiciiiTE. Lettsomitc. Kupfersammterz, Germ. — In velvety druses. Color blue. A hydrous sulphate of copper and aluminum. Moldavain the Banat. WOODWARDITE, near the above. KunNKiTE — CUSO4 4- Na2S04 + 2aq=Copper sulphate 47*2, sodium sulphate 421, water 10'7=100. In irregular crystalline masses of a coarse fibrous structure, prismatic. Color azure-blue. Moist to the touch. Found in the copper mines near Calama, Bolivia. (Domeyko.^ Pnn.i.iPfTK. — CuS04 + i*eS;,Oi2 + waq. In irregular fibrous masses, not prismatic. Coloj blu(\ In the cordilleras of Condes, Santiago, Chili. (Domeyko. ) EXYSITE.— Occurs in stalactitic forms in a cave. H. =:2-2"4. G. =1"59. Color bluish- green. B.B. infusible. Analysis: SO3 8-12, AIO3 29-85, CuO 16-91, CaO 1-85, H.O 3942, SiO, 3-40. COo 1 05 = 100. Near St. Agnes, Cornwall. (Collins, Min Mag., 1, p. 14.) UitANiUM-suLPHATES. — There are included herejohaiinite, iwauockalcUe, medjidite, zliypeite, vo'jlianite, uraconiie. These are secondary products found with other uiauinm minerals at JokchimsthaL Tellueates. MONTANITE. Incmsting ; without distinct crystalline structure. Soft and earthy. Lustre dull to waxy. Color yellowish to white. Opaque. Comp.— Bi2Te06-l-2aq=Tellurium trioxide 26-1, bismuth oxide 68-6, water 5-3=100, Pyr., etc. — ^Yields water in a tube when heated, B.B. gives the reactions of bismuth and tellurium. Soluble in dilute hydrochloric acid. Obs. — Incrusts tetradymite, at Highland, in Montana ; Davidson Co. , N. C. 398 DE8CKIPTIVE MTNEKALOOY. 7. CARBONATES. Aneydrous Carbonates. Calcite Group. CALCITE. Calo Spar. Kalkspath, Gtrm. Rhorabohedral. RhR, terminal, = 105° 5', 6>A^ = 135° 23'; ) Stalag- mite is the same material covering the floors of caverns, it being made from the waters that drop from the roofs, or from sources over the bottom or sides ; cones of it sometimes rise from the floor to meet the stalactites above. (c) Calc-sinter, Travertine, Calc Tufa. Traxerivixe (Con fetto di Tivoli) is of. esseniiaWy fhe same origin with stalagmite, but is distinctively a deposit from springs or rivers, especially where in large deposits, as along the river Anio, at Tivoli. near Rome, where the deposit is scores of feet in thickness. It has a very cavernous and irregulaiiy banded structure, owing to its mode of formation. (rf) Agaric mineral; Rock-milk [Bergmilch, Montmilch, Germ.) is a very soft, white material, breaking easily in the fingers, dei^osited sometimes in caverns, or about sources holding lima in solution. OXYGEN COMPOTJNDS. — CAKBONATES. 401 («) Rock-meal [BergmeM, Germ.) is white and light, like cotton, becoming a powder on tlie slightest pressure. It is an efflorescence, and is common near Paris, especially at the quarries of Nanterre. Pyr., et3. — In the closed tube sometimes decrepitates, and, if containing metallic oxides may change its color. B.B. infusible, but becomes caustic, glows, and colors the tlauie red after ignition the a.ssay reacts alkaline ; moistened with hydrochloric acid imparts the charac- teristic lime color to the tlame. In borax dissolves with effervescence, and if saturated, j-ields on cooling an opaque, milk-white, crystalline bead. Varieties containing metallic oxides color the borax and salt of phosphorus beads accordingly. With soda on platinum foil fuses to a clear mass; on charcoal it at first fuses, but later the soda is absorbed by the coal, leaving an infusible and strongly luminous residue of lime. In the solid mass effervesces when moistened with hydrochloric acid, and fragments dissolve with brisk effervescence even iu cold acid. Diflf. — Distinguishing characters : perfect rhombohedral cleavage ; softness, can be scratched with a knife ; effervescence in cold ddute acid ; inf usibUity. Less hard and of lower specific gravity than aragonite. Obs. — Andreasberg in the Harz is one of the best European localities of crystallized calcite ; there are other localities in the Tyrol, Styria, Carinthia, Hungary, Saxony, Hesse Darmstadt (at Auerbach), Hesse Cassel, Norway, France, and in England in Derbyshire, Cumberland, Cornwall ; Scotland ; in Iceland. In the U. States prominent localities are : in If. York, in St. Lawrence and Jefferson Cos., especially at the Rossie lead mine ; in Antwerp; dofj-tooth spnr, in Niagara Co., near Lock- port ; near Booueville, Oneida Co. ; at Anthony's Xose, on the Hudson ; at Watertown, Agaric mineral \ at Schoharie, fine stalactites in many caverns. In Conn., at the lead mine, Middletown In N. Jersey, at Bergen. In Virginia, at the celebrated Wier's cave. i> of great beauty; also in the large caves of Keittucky. At the Lake Superior copper mines, splendid crystals often containing scales of native copper. At Warsaw, Illinois j at Quincy. lU.; at Hazle Green, Wis. In Nova Scotia, at Partridge I. DOLOMITE. Rhombohedral. RhR = 106° 15', OhR- 136° 8^' ; c = 0-8322. RhE varies between 106° 10' and 106° 20'. Cleavage : R perfect. Faces R often curved, and secondary planes usually with horizontal striae. Twins : similar to f . 733. Also in imitative shapes ; also amorphous, granular, coarse or fine, and grains often slightly coherent. H.=3-5-4. G. = 2-8-2-9, true dolomite. Lustre vit- reous, inclining to pearly in some varieties. Color white, reddish, or green- ish-wliite ; also rose-red, green, brown, gray, and black. Subtransparent to translucent. Brittle. Comp., Var. — (Ca,]yig)C03, the ratio of Ca : Mg in normal or true dolomite is 1 : l=Cal- cium carbonate o-t'oo, magnesium carbonate 45 05. Some kinds included under the name have other proportions ; but this may arise from their being mixtures of dolomite with calcite or magnesite. Iron, manganese, and more rarely cobalt or zinc are sometimes present. The varieties are the following : Crystallized, i'earl spar includes rhombohedral crystallizations with curved faces. Colum- nar or fibrous. Granular constitutes manj' of the kinds of white wtatuary marble, and white and colored architectural marbles, names of some of which have been mentioned under calcite. Compact ma.ssive, like ordinary limestone. Many of the limestone strata of the globe are here included, and much hydraulic limestone, noticed under calcite. Ferriferous : Brown spar, in part. Contains iron, and as the proportion increases it gradu- ates into ankerite (q. v.). The color is white to brown, and becomes brownish on exposure through oxidation of the iron. Manganiferoits. Colorless to fleah-red. i2Ai?=106^ 23' ' 106MG. Cohaltiferous. Colored reddish ; G. =2-921, Gibbs. The varieties based on variations in the proportions of the carbonates are the following ; (a) Normal dr^mite, ratio of Ca to Mg=l : \, (b) ratio H •" 1=3 : 2 ; ratio=:2 : 1 ; ratio 3 : 1 ; ratio=5 : 1 ; ratio 1 : 3. The last (/) may be dolomitic magnesite ; and the others, from 26 402 DESCRIPTIVE MINERALOOr. (5). dolomitic calcite, or calcite + dolomite. The manner in which dolomite is ofted mixed wiLh calcite, forming its veins and its fossil shells (see below), shows that this is not improb- able. Pyr., etc. — B.B. acts like calcite, but does not give a clear mass when fused with soda on platinum foil. Fragments thrown into cold acid are very slowly acted upon, while in powder in warm acid the mineral is readily dissolved with effervescence. The ferriferous dolomites become brown on exposure. Diff.- -Resembles calcite, but generally to be distinguished in that it does not effervesce readily in the mass in cold acid. Obs. — Massive dolomite constitutes extensive strata, called limestone strata, in various regions. Crystalline and comi)act varieties are often associated with serjientine and other magnesian rocks, and with ordinary limestones. Some of the prominent localities are at Salz- burg ; the Tyrol ; Schemnitz in Hungary ; Kapnik iu Transylvania ; Freiberg in Saxony ; the lead mines at Alston in Derbyshire, etc. In the U. States, in Vermont, at Roxbui-y. In Rhode Tdand, at Smithfield. In N". Jcruy, at Iloboken. In N. York, at Lockport, Niagara Falls, and Rochester ; also at Glenn's Falls, in Richmond Co., and at the Parish ore bed, St Lawrence Co.; at Brewster, Putnam Co. Named after Dolomieu, who announced some of the marked characteristics of the reck in 1791 — its not effervescing with acids, while burning like limestone, and its solubility after heating in acids. ANKERITE. Rhomhohedral. i?A^ = 106°7', Zepharovich. Also crystalline mas- sive, coarse or fine granular, and compact. H.=3"5-4. G. = 2-95-3*l. Lustre vitreous to pearly. Color white, gray, reddish. Translncciit to subtransliiccnt. Comp. — CaCOs+FeCOg+^CCaMgCoO,,). Here, according toBoricky, .t may have the values t, 1, ^, f, f, 2, 3, 4, 5, 10. The varieties having the five higher values of x he calls paran- kente, while the others are normal ankerite. If x=l, the formula is equivalent to 2CaC03 4- MgCOa + FeCOs, and requires: Calcium carbonate 5'\ magnesium carbonate 21, iron carbon- ate 29 = 100. Manganese is also sometimes present. Pyr., etc. — B.B. like dolomite, but darkens in color, and on charcoal becomes black and magnetic ; with the fluxes reacts for iron and manganese. Soluble with effervescence in the acids. Obs. — Occurs with siderite at the Styrian mines ; in Bohemia; Siegen ; Schneeberg; Nova Scotia, etc. / MAGNESITE. Ehomhohedral. J^ A B = 107° 29', (9 A 7? = 136° 56' ; c = 0-8095. Cleavage: rhombohedral, perfect. Also massive; granular, to very com- pact. H.=n:3-5-4-5. G. = 3-3-08, cryst. ; 2-8, earthy; 3-3-2, when ferriferons. Lustre vitreous; fibrous varieties sometimes silky. Color white, yellowish or grayish-white, lu'own. Transpai-ent— opaque. Fracture flat conchoidal. Var. — Ferriferovx, Breunerite ; containing several p. c. of iron protoxide; G. =3-3-2, white, yellowish, brownish, rarely black and bituminous; often becoming brown on exposure, and hence called Brown Spnr. Comp. — Magnesium carbonate, MgC03 = Carbon dioxide 52 4, magnesia 4'i •6 = 100; but iron often replacing some magnesium. Pyr., etc.— B. I'., resembles calcite and dolomite, and like the latter is but slightly acted upon by cold acids ; in powder is readily dissolved with effervescence in warm hydrochloric acid. Obs. — Found in talcose schist, serpentine, and other magnesian rocks ; as veins in serpen- tine, or mixed with it so as to form a variety of verd-antique marble (magaesiUo ophidite of OXYGEN COMPOUNDS. — CARBONATES 403 735 Hunt) ; also in Canada, as a rock, more or less pure, associated with steatite, serpentine, and dolomite. Occurs at Hrubschiitz in Moravia; in Styria, and in the Tyrol; at Frankenstein in Silesia; Snarura, Norway ; Baudissero and Castellamonte in Piedmont. In America, at Bolton, Mass.; at Barehills, near Baltimore, Md. ; in Penn., at West G-oshen, Chester Co. ; near Texas, Lan- /Caster Co. ; California. ^ Mesititr and PiSTOMESiTE come under the general formula (Mg,Fe)C03 ; with the formei Mg : Fe=2 : 1 ; with the latter=l : 1. ^ SIDE RITE. Spathic Iron. Chalybite. Eisenspath, Gsrm. Rhoinbohcdi-al. RaR= 107°, A Ji == 130° 37' ; c = 0-81715. The faces often curved, as below. Cleavage: rhoiii- bohedral, perfect. Twins: twinning-plane — -1. Also in l)Oti-yoidal and globular forms, sub- fibrons within, occasionally silky fibrous. Often cleavable massive, with cleavage planes undu- lating. Coarse or fine gi-anular. H.'=3-5-4-5. G. = 3-7-3-9. Lustre vitreous, more or less pearly. Streak white. Color ash- gray, yellowish-gray, greenish-graj', also brown and brownish-red, i-arely green ; and sometimes white. Translucent — subtranslucent. Fracture uneven. Brittle. Comp., Var. — Iron carbonate, FeC03 = Carbon dioxide o7'9, iron protoxide 631. But part of the iron usually replaced by manganese, and often by raagnesium or calcium. Soma varieties contain 8-10 p. c. MnO. The principal varieties are the following : (1) Ordi/inri/. {a) Cri/-s(aUized. [b) €'oncretionat-7/=Sp7ierosiderite ; in glohnlciT concretions, either solid or concentric scaly, with usually a fibrous structure, (c) Granuhtr to compact mas- site. (d) Odlitic, like oolitic limestone in structure. {e) Earthy, or stony, impure from mixture with clay or sand, con.stituting a large part of the clay iron-stone of the coal forma- tion and other stratified deposits ; H. ^=3 to 7, the last from the silica present ; G. =3'0-3"8, or mostly 8 15-3()o. Pyr., eto. — In the closed tube decrepitates, evolves carbon oxide and carbon dioxide, blackens and becomes magnetic. B.B. blackens and fuses at 4o. With the fluxes reacts for iron, and with soda and nitre on platinum foil generally gives a manganese reaction. Only slowly acted upon by cold acid, but dissolves with brisk effervescence in hot hydrochloric acid. Diff. — Specific gravity higher than that of calcite and dolomite. B.B. becomes magnetic readily. Obs. — Siderite occurs in many of the rock strata, in gneiss, mica slate, clay slate, and aa clay iron-stone in connection with the Coal formation and many other stratified deposits. It is often associated with metallic ores. At Freiberg it occurs in silver mines. In Cornwall it accompanies tin. It is also found accompanying copper and iron i:)yrites, galenite, vitreous copper, etc. In New York, according to Beck, it is almost always associated with specular iron. In the region in and about Styria and Carinthia this ore forms extensive tracts in gneiss. At Harzgerode in the Harz, it occurs in fine crystals; also in Cornwall. Alston- Moor, and Devonshire ; near Glasgow ; also at iMouillar, Magescote, etc.. in France, etc. In the U. States, in Vermont, at Plymouth. In Mum., at Sterling. In Conn., at Roxbury. In N. Fork, at the Sterling ore bed in Antwerp, Jeflierson Co. ; at the Rossie iron mines, St. Lawrence Co. In N. CaroUiui, at Fentress and Harlem mines. The argillaceous carbonate, in nodules and beds (clay iron-stone), is abundant in the coal regions of Penn., Ohio, and manj parts of the country. J RHODOCHROSITE.* Dialogite. Manganspath, Germ. RhombohedraL R/\R = 10()° 51', 6>a7?=136° 31^; 6' = 0-S211. Cleavage : 7?, jierfect. Also globular and botryoidal, having a columiiai structure, sometimes indistinct. Also granular massive; occasionally im palpable; iucrusting. 401 DESCRIPTIVE MINERALOGT. H. =3'5-4-5. G. = 3*4-3-7. Lustre vitreous, inclining to pearly, Coloi shades of rose-red, yellowish-gray, fawn-colored, dark red, bi-own. Streak white. Translncent — subtranslucent. Fracture uneven. Brittle. Comp. — MnC03=Carbon dioxide 383, manganese protoxide 61 7; but part of tlie man- ganese usually replaced by calcium, and often also by magnesium or iron ; and sometimes by cobalt. Pyr., etc. — B.B. changfs to gray, brown, and black, and decrepitates strongly, but is in- fusible. With salt of phosphorus and borax in O.F. gives an amethystine-colored bead in II.F. becomes colorless. With soda on platinum foil a bluish-green manganate. Dissolves with effervescence in warm hj'drocbloric acid. On exposure to the air changes to brown, and pome bright rose-red varieties become paler. Obs. — Occurs commonly in veins along with ores of silver, lead, and copper, and with other ores of manganese. Found at Sc.hemuitz and Kapnik in Hungary ; Nagyag in Transylvania ; near Elbingerode in the Harz ; at Freiberg in Saxony. Occurs in New Jersey, at Mine Hill, Franklin Furnace. Abundant at the silver mines of Austin, Nevada ; at Placentia Bay, Newfoundland. Named rhodochrosite from p6^ov, a rose, and xp^^c's, color ; and dialogite, from Sia\oyf), doabt. J SMITHSONITE. Calamine pt. Galmei pt. Zinkspath, Genn. Ehombohedral. Ji A Ji = 107° 40', OaR = 137° 3' ; c = 0-8062. Ji generally curved and rough. Cleavage : Ji perfect. Also renifonn, botry- oidal, or stalactitic, and in crystalline incrustations ; also gnuiular, and sometimes impalpable, occasionally earthy and friable. H. = 5. G.=4-4'45. Lustre vitreous,. inclining to pearly. Streak white. Color white, often grayish, greenish, brownish-white, sometimes green and brown. Subtransparent — translucent. Fracture uneven — imperfectly conchoidal. Brittle. Comp., Var. — ZnCOs^Carbon dioxide 33 S, zinc oxide 64-8 = 100; but -part of the zinc often replaced by iron or manganese, and by traces of calcium and magnesium ; sometimes by cadmium. Varieties. — (1) Oi'dinary. (a) Ci'pstaUized ; (b) botryoidal and stnlnctitic, common; (c) granular to compact mo usite ; (d) eai-thy, impure, in nodular and cavernous masses, varying from grayish-white to dark gray, brown, brownish-red, brownish-black, and often with drusy surfaces in the cavities ; "dry-bone " of American miners. Pyr., etc. — In the closed tube loses carbon dioxide, and, if pure, is yellow while hot and colorless on cooling. B.B. infusible; moistened with cobalt solution and heated in O.F. gives a green color on cooling. With soda on charcoal gives zinc vapors, and coats the coal yellow while hot, becoming white on cooling ; this coating, moistened with cobalt solution, gives a green color after heating in 0. F. Cadmiferous varieties, when treated with soda, give at first a deep yellow or brown coating before the zinc coating appears. With the fluxes some varieties react for iron, coiiper, and manganese. Soluble in hydrochloric acid with efferves- cence. Diff. — Distinguished from calamine by its effervescence in acids. Obs. — Smithsonite is found both in veins and beds, especially in company with galenite and blende ; also with copper and iron ores. It usually occurs in calcareous rocks, and ia generally associated vrith calamine, and sometimes with limonite. It is often produced by the action of zinc sulphate upon calcium or magnesium carbonate. Found at Nertschinsk in Siberia ; at Dognatzka in Hungary ; Bleiberg and Raibel in Carin- thia; Moresnet in Belgium. In England, at Roughten Gill, Alston Moor, near Matlock, in the Mendip Hills, and elsewhere; in Scotland, at Leadhills; in Ireland, at Donegal. In the U. States, in N. Jerney, at Mine Hill, near the Franklin Furnace. In Pcnn., at Lancaster abundant ; at the Perkiomen lead mine ; at the Ueberroth mine, near Bethlehem. In Wisconsin, at Mineral Point, ShuUsburg, etc. In Minnesota, at Ewing's diggings, N. W. of Dubuque, etc. In Missouri and Arkansas, along witli the lead ores in Lower Silurian limestone. OXYGEN COMPOUNDS. CARBONATES. 405 Aragonite Group, "^ARAGONITE. Orthorhombic I^l = 116° 10', OM-l=: 130° 50' ; c'.l'.d-. 1-1571 : 1 -0055 : 1. M = 126° 15', OM-l = 137° 15', 1-i A \-i, top, := 108= 26'. Crystals usually having O striated parallel to the shorter diagonal ; often tapering from the presence of acute domes and pyramids, which have unusual indi(;es. Cleavage: I imperfect; i-i distinct; l-i imj)erfect. Twins : twinning-plane 7, producing often hexagonal forms, f. 738, compare figures on pp. 96, 97. Twinning often many times repeated in the same crystal, producing successive reversed layers, the alternate of which may be exceedingly thin ; often so delicate as to produce by the succession a iine striation of the faces of a prism or of a cleavage plane. Also globular, reniform, and coralloidal shapes ; sometimes columnar, composed of straight and divergent fibres; also stalactitic; incrusting. 737 738 /fSi7 \\j^^L^ H.= 3*5-4. G. =2*931, Haidinger. Lustre vitreous, sometimes inclin- ing to resinous on surfaces of fracture. Color white ; also gra}^ yellow, green, and violet ; streak uncolored. Transparent — translucent. Fracture subconchoidal. Brittle. Var. — 1. Ordinary, {a) Crystallized in simple or compound crystals, the latter much the most common ; often in radiating groups of acicular crystals, (b) Columnar ; a fine fibrous variety with silky lustre is called iSatiii spar, (c) Massive. Stalactitio or stalngmitic (either compact or fibrous in structure), as with calcite ; Sprudelstein is stalactitic from Carlsbad. Coralloidal ; in groupings of delicate interlacing and coalescing stems, of a snow-white color, and looking a little like coral. Comp. — CaCOs, Uke calcite, = Carbon dioxide 44, lime .IG^IOO. Pyr., etc. — B.B. whitens and falls to pieces, and sometimes, when containing strontia, im- parts a more intensely red color to the flame than lime ; otherwise reacts like calcite. Diflf.— See calcite, p. 401. Obs. — The most common repositories of aragonite are beds of gypsum, beds of iron ore (where it occurs in coralloidal forms, and is denominated flos-ferri, ''flower of iron,.,'''' Eisen- bliithe, Germ.), basalt, and trap rock; occasionally it occurs in lavas. It is often associated with copper and pyrite, galenite, and malachite. First discovered in Aragon, Spain (whence its name), at Molina and Valencia. Since £oaud at Bilin in Bohemia ; at Herrengrund in Hungary, f , 738 ; at Baumgarten in Silesia ; 406 DESCEIPXrVE MINERALOGY. at Leogan^ in Salzburg ; in Waltsch, Bohemia, and many other places. The flonferri varietur is foiind in great perfection in the Styrian mines. In Buckinghamshire, Devonshire, ux caverns; at Leadhills in Lanarkshire. Occurs in serjjentine at Hoboken, N. J.; at Edenville, N. Y.; at the Parish ore bed, Rossie, N. Y.; at Haddam. Conn.; at New Garden, in Chester Co., Penn. ; at Wood's Mine, Lanca«i- ter Co. , Penn.; at Warsaw, 111. , lining geodes. Manganocalcite. — Composition 2MnC03-h(Ca,Mg)C03, with a little iron replacing part of the manganese. G. =3-087. Color flesh-red to reddish-white. Schemnitz, Hungary. WITHERTTE. Orthorliombic. /A /= 118° 30', OM-l = 128° 45' ; c:l:d = 1-246 : 1*6808 : 1. Twins : all the annexed figures, com- position parallel to /; reentering angles some- times observed. Cleavage : / d^tinct ; also in globulai-, tuberv)se. and botryoidal forms; struc- ture either columnar or granular ; also amor- phous. H. = 3-3-75. G. = 4-29-4-35. Lustre vitreous, inclining to resinous, on surfaces of fracture. Color white, often yellowish, or grayish. Streak white. Subtransparent — translucent. Fracture uneven. Brittle. Comp.—BaC03 = Carbon dioxide 22 3, baryta 77-7-100. Pyr., etc. — B.B. fuses at 2 to a bead, coloring the flame yel- lowish-green; after fusion reacts alkaline. B.B. on charcoal with soda fuses easily, and is absorbed hy the coal. Soluble in dilute hydrochloric acid; this solution, even when very much diluted, gives with sulphuric acid a white precipitate which is insoluble in acids. Diflf. — Distinguishing characters : high specific gravity ; effervescence with acids ; green coloration of the flame B.B. Obs. — Occurs at Alston-Moor in Cumberland ; at Fallowfield, near Hexham in Northumber- land ; Tarnowitz in Silesia ; Leogang in Salzburg ; Peggau in Styria ; some places in Sicily ; the mine of Arqueros, near Coquimbo, Chili; near Lexington, Ky., with barite. Witherite is extensively mined at Fallowfield, and is used in chemical works in the manu- facture of plate-glass, and in France in making beet- sugar. Bkomlite. — Formula as for barytocalcite, but orthorhombic in form. J STRONTIANITE. Orthorhombic. /A /= 117° 19', OM-l = 130° 5' ; c:l:d = 1-1883 : 1-6421 : 1. 6> A 1 = 125° 43', OM-i = 144° 6', 1 A 1, mac, = 130° 1', 1 A 1, brack, = 92° 11'. Cleavage : 1 nearly perfect, i-l in traces. Crys- tals often acicular and in divergent groups. Twins: like those of aragonite. O usually stri- ated parallel to the shoiler diagoiuil. Also in columnar globular forms ; iibrous and granulai'. II. = 3-5-4. G. = 3-605-3-713. Lustre vitre- inclining to resinous on uneven faces of ous Olio, ijijuiiiiiiig y,y) iconiv.»i4o ym iijn.->v-ii xt\,\j\,a ^^ Color j)ale aspai-agus-green, apple-green ; also white, gray, yel- yellowish-brown. Streak white. Transparent — translucent. fracture. low, and Fracture uneven. Biittle. OXYGEN COMPOUNDS. CARBONATES. 407 Comp.—SrC03 = Carbon dioxide 29 7, strontia 703 ; but a small part of the strontium often replaced by calcium. Pyr., etc. — B.B. swells up, throws out minute sprouts, fuses only on the thin edges, and colors the flame strontiared ; the assay reacts alkaliue after ignitinn. Moistened with hydro- chloric acid and treated either B.B. or in the naked lamp gives an intense red color. With soda on charcoal the pure mineral fuses to a clear glass, and is entirely absorbed by the coal ; Lf lime or iron be present they are separated and remain on the surface of the coal. Soluble in hydrochloric acid ; the dilute solution when treated with sulphuric acid gives a white pre- cipitate. Diff. — Differs from related minerals, not carbonates, in effervescing with acids ; lower specific gravity than witherite, and colors the tlaine 7'ed. Obs. — Occurs at Strontian in Argyleshire ; in Yorkshire, England ; Giant's Causeway, Ire- land ; Clausthal in the Harz ; Braunsdorf , Saxony ; Leogang in Salzburg. In the U. States it occurs at Schoharie, N. Y., in granular and columnar masses, and also in crystals. At Muscalonge Lake; at Chaumont Bay and Theresa, in Jefferson Co., N. Y. ; Mifflin Co., Perm V CERUSSITE. Weissbleierz, Bleispath, Germ. 745 746 Orthorhoinbic. /A /= 117° 13', A l-l = 130° 9^' ; c:b:d= 1-1853 : 1-6388 : 1. O A 1 = 125° 46', 6>Al4=14^-° 8', lAl, mac, = 130°, 1 A 1, brach., = 92° 19'. Cleavage: /often imperfe(;t ; 2-t hardly less so. Crystals usually thin, broad, and brittle ; souietiines stout. Twins : very common ; twin- ning-plane ly producing usu- ally cruciform or stellate forms ; also less commonly, twinuing-plane i-L Ilarely fibrous, often granular mas- sive and compact. Sometimes stalactitic;. II. = 3-3-5. G.=:6-465-6'480 ; some earthy varieties as lovt^ as .5-4w Lustre adamantine, inclining to vitreous or resinous; sometimes pearly; sometimes submetallic, if the colors are dark, or from a superficial change. Color white, giay, grayish-black, sometimes tinged blue or green by some of the salts of copper; streak uncolored. Transparent — subtranslucent. Fracture conclioidal. Very brittle. Comp PbC03=Carbon dioxide 16-5, lead oxide 83-5=100. Pyr., etc.— In the closed tube decrepitates, loses carbon dioxide, turns first yellow, and at a higher temperature dark red, but becomes yellow again on cooling. B.B. on charcoal fuses very easily, and in R.F. yields metallic lead. Soluble in dilute nitric acid with effervescence. Diflf. — Unlike anglesite, it effervesces with nitric acid. Characterized by high specific gravity, and yielding lead B.B. Obs. — Occurs in counection with other lead minerals, and is formed from galenite, which, as it passes to a sulphate, may be changed to carbonate by means of solutions of calcium bicarbonate. It is found at Johanngeorgenstadt ; at Nertschinsk and Bere.sof in Siberia ; at Clausthal in the Harz ; at Bleiberg in Carinthia ; at Mies and Przibram in Bohemia ; at Retz- banya, Hungary; in England, in Cornwall; near Matlock and Wirksworth, Derbyshire; at Leadhills, Scotland ; in Wicklow, Ireland. Found in Fe?in. , at Phenixville ; at Perkiomen. In iV. York, at the Rossie lead mine. In Virrjinia, at Austin's mines, Wythe Co. In iV. Carolina, at King's mine, Davidson Co. , good. In Wisconsin and other lead mines of the northwestern States, rarely in crystals; near the Blue Mounds, Wise. , in stalactites. 408 DESCKIPITVE ^mSTEKALOGY. / BARYTOOALCITE. Monoclinie. C - 73° 52', /A /= 106° 54', 6> A l-l = 149" ; c\l\a-- 0'81035 : 1"29583 : 1. Cleavage: /, perfect; 6>, less perfect ; also massive. fl.=4. G. = 3-6363-3*66. Lustre vitreous, inclining to resinous. Color white, gra^'ish. greenish, or yellowish. Streak white. Transparent — translucent. Fracture uneveri. Comp. — (Ba,Ca)C03, where Ba : Ca=l : l=Bariuin carbonate 663, calcium carbonate 33-7=100. Pyr., etc. — B.B. colors the flame yellowish -green, and at a higher temperature fuses or. the thin edges and assumes a pale green color ; the assay reacts alkaline after ignition. With the fluxes reacts for manganese. With soda on charcoal the lime is separated as an infusible mass, while the remainder is absorbed by the coal. Soluble in dilute hydrochloric acid. Obs. — Occurs at Alston-Moor in Cumberland, in the Subcarboniferous or mountain lime- stone. Pakisite. — A carbonate containing cerium (also La,Di), and calcium with 6 p. c. fluorine. Exact composition uncertain. In hexagonal crystals. Color brownish-yellow. Mu.50 valley, New Granada. KisciiTiMlTE, from the gold washing of the Barsovska river, Urals, is similar in composition, but contains no calcium. Bastnasite (Hamartite). — Composition 2RCO3+RF.., with R=Ce : La=2 : 3. Analysis, Nordenskiol.l, CO.2 19-50, LaO 45-77, CeO 28-49, H,0 101, F,0, (5-23) = 100. Found in small masses imbeddM between allanite crystals. Riddarhyttan, Sweden. PHOSGENITE. Bleihornerz, Germ. Tetragonal. 6> A 1-^ = 132° 37'; c = 1-0871. Cleavage: / and i-i bright ; also basal. H. = 2'75-3. G. = 6-6'31. Lustre adamantine. Color white, gray, and yellow. Streak white Transparent — translucent. Rather sectile. Comp. — PbCOa-f PbCl2=Lead carbonate 49, lead chloride 51=100, or lead oxide 81 -9, car- bon dioxide 8-1, chlorine 13-0 = 102-9. Pyr., etc. — B.B. melts readily to a yellow globule, which on cooling becomes white and crystalline. On charcoal in R.F. gives metallic lead, with a white coating of lead chloride. With a salt of phosphorus bead previously saturated with copper oxide gives the chlorine reaction. Dissolves with effervescence in nitric acid. Obs. — At Cronrford near Matlock in Derbyshire ; very rare in Cornwall ; in large crystak at Gibbas and Monteponi in Sardinia ; near Bobrek in Upper Silesia, HyDKOUS CAEBONATiiB. TRONA. Monoclinic. (9 A ^-^ = 103° 15'. Cleavage :«-** perfect. Often fibroaa or columnar massive. H. = 2-5-3. G. = 2-ll, Lustre vitreous, glistening. Color gray or jcl- lowish-white. Translucent. Taste alkaline. Not altered by exposure to a dry atmosphere. Comp Na4C,08+3aq=Carbon dioxide 40-2. soda 378. water 220. Pyr., etc. — In the closed tube yields water and carbon dioxide. B.B. imparts an intensely yellow color to the flame. Soluble in water, and efiEervesces with acids. Reacts alkaline with moistened test paper. Obs. — The specimen analyzed by Klaproth came from the province of Suckenna, two days' journey from Fezzen, ica. To this species belongs the urao found at tha bottom of a lake OXYGEN COMPOUNDS. CARBONATES. 409 hi Maracaibo, S. A. , a day's journey from Merida. EfBorescences of trona occur near the Sweetwater river, Rocky Mountaius, mixed with sodium sulphate and jommon salt. Natron or Soda (sodium carbonate, NajCOa+lOaq). Thermonatrite, NajCOa + aq. Teschemacherite. Ammonium carbonate. Maracaibo. Nevada. GAY-LUSSITE. Monocliuic. C = 78° 27', /a /= 68° 50' and 111° 10', A 1-i = 125° 15' ; c:b:d = 0-96945 : 0-67137 : 1. 14 A 14, adj., = 109° 30', ^ A i = 110° 30'. Crystals often len^rthened, and prismatic in the direction of 14 ; also in that of ^ ; also (f r. Nevada) not elongate, but thin in the direction of the orthodia- goiial, O being very narrow or -wanting ; snrfaces usually nneveu, being formed of minute subordinate planes. Cleav- age : / perfect ; O less so, but giving a retlected image in a strong light. H.=2-3. G. = 1-92-1^99. Lustre vitreous. Color white, yellowish- white. Streak nncolored to grayish. Translucent. Fracture conclioidal. Extremely brittle. Not phosphorescent by friction or heat. Oomp. — Na3C03 + CaC03 + 5aq= Sodium carbonate 35 "9, calcium carbonate 33 8, water 30-3 = 100. Pyr., etc. — Heated in a matrass the crystals decrepitate and become opaque. B B fuses easily to a white enamel, and colors the flame intensely yellow. With the fluxes it behaves like calcium carbonate. Dissolves in acids with a brisk effervescence ; partly soluble in water, and reddens turmeric. Obs. — Abundant at Lagunilla, near Merida, in Maracaibo, where its cry.stals are dis-semi- nated at the bottom of a small lake, in a bed of clay, covering unto ; the natives call it clavos or iKiils, in allusion to its ci';5stalline form. Also on a smal] island in Little Salt Lake, near Ragtown, Nevada, about 1^ m. S. of the main emigrant road to Humboldt. The lake is in a crater-shaped basin, and its watei's are dense and strongly saline. The distorted crystals from Sangerhausen have been long considered pseudomorphs after gay-hissite, though Des Cloizeaux regards them as pseudomorphs after celestite. Groth regards them as perhaps pseudomorphs after anhydrite. See also thinolite, p. 438. H7DROM AGNE SITE. (7=82"-S3°, I A 1=87° 52'-88°, 6> A 24 = 137°; e Crystals small, usually Also amorphous ; as Monocliuic : d = (nearly) 0455 : 1-0973 : 1. acicular or bladed, and tufted, chalkv or mealy crusts. II. of crystals 3-5. G. = 2-li5-2-18. Smith & Brush. Lustre vitreous to silky or subpearly ; also earthy. Color and streak white. Brittle. Comp.—3MgC03 + H2MgOj-|-3aq= Carbon dioxide 36-3, magnesia 43-9. water 19 -ft = 100. Pyr., etc. — In the closed tube gives off water and carbon dioxide. B.B. infusible, but whitens, and the assay reacts alkaline to tuimeric paper. Soluble in acids ; the crystalline compact varieties are but slowly acted upon by cold acid, but dissolves with effervescence in hot acid. 410 DESCRIPTIVE MINERALOGY. Cpbs — Occurs at Hrubschitz, in Moravia, in serpentine; in Negroponte, near Kami; at Kaiserstuhl, in Baden, impure. In the U. States, near Texas, Lancaster Co., Peim. ; at Hoboken, N. J. Hyuuodolo. MITE. —Composition 3(CaMg)C03H-aq. From Mt Somma. PK.N>aTE from Texas, Pa. . is similar. Pkedazzite and Pencatite are mixtures of calcite and brucite. Tyrol. Dawsonite.— In thin-bladed, white, transparent crystals on trachyte. 11.=;). G.=2-40. Analysis, Harrington, 7VIO3 ;53 84, MgO tr., CaO 5-!)5, Na,0 20-20, K.O 38, H.,0 II-'JI. CO, 29'88, SiOo 0-40--101'5G. Regarded as '' a hydrous carbonate of aluminum, calcium, and )?odium ; or perhaps as a hydrate of aluminum with carbonates of calcium and sodium." Montreal, Canada. HoviTE. — Supposed to be a hydrous carbonate of aluminum and calcium. Soft, white, and friable; earthy in fracture. From Hove, near Bri-hton, with colly rite. LANTHANITE. Orthorhombic. 7a 7= 93° 30'-94°, Blake, 92° 46', v. Lan^r ; /a 1 :^ 142° 36' ; c:b'.d = 0-99898 : 1-0496 : 1, v. Lang. In thin four-sided plates or minute tables, with bevelled edges. Cleavage micaceous. Also fine granular or earthy. H. = 2-5 — 3. G. = 2-666. Lustre pearly or dull. Color grayish-white, delicate pink, or yellowish. Comp.— LaC03-l-3aq=Lanthana 52*6, carbon dioxide 21-3, water 26-1=100. There is some oxide of didymium with the lauthana, according to Smith. Pyr., etc — In the closed tube yields water. B.B. infusible ; but whitens and becomes opaque, silvery, and brownish ; \vith borax, a glass, slightly bluish, reddish, or amethystine, on cooling ; with salt of phosphorus a glass, bluish amethystine while hot, red cold, the bead becoming opaque when but slightly heated, and retaining a pmk color. Effervesces in the acids. Obs. — Found coating cerite at Bastnis, Sweden ; also with the zinc ores of the Saucon valley, Lehigh Co., Pa. ; at the Sandford iron-ore bed, Moriah, Essex Co.. N. Y. Tengerite.— Yttrium carbonate. As a coating on gadolinite from Ytterby. Zaratite. Emerald Nickel, iSillima/i. Nickelsmaragd, &'€/■;«.— Composition NigCOs-f- 6aq, or NiC03 + 2H.NiO,-l-4aq. This requires: Carbon dioxide 11-8, nickel oxide 59-3, water 28 "9 = 100. Usually as an emerald-green coating; thus on chromite at Texas, Peim., where it was first noticed ; Swinaness, Shetland ; Cape Ortegal, Spain. Eemingtonite.— A hydrous cobalt carbonate. Finksburg, Md. y HYDROZINCITE. Zinkbliithe, Oerm. Massive, earthy or compact. As incrustations, the crusts sometimes con- centric and agate-like. At times reniform, pisolitic, stalactitic. H. = 2-2-5. G.=3-5S-3-8. Lustre dull. Color pui-e white, grayish or yellowish. Streak shining. Usually earthy or chalk-like. Comp — In part ZnCOa -I- 2H2ZnO, = Carbon dioxide 18-6, zinc oxide 75-3, water 11-1=100. Pyr., etc. — In the closed tube yields water ; in other respects resembles smithsonite. Obs. — Occurs at most mines of zinc, and is a result of the alteration of the other ores oi this metal. Found in great quantities at the Dolores mine, Udias valley, province of Santan- der, in Spain ; at Bleiberg and Raibel in Carinthia ; near Reimsbeck, in Westphalia In the U. States, at FriedensviUe, Pa.; at Linden, in Wisconsin; in Marion Co., Arkansas {marionite) . AuRiCHAiiCiTE. — A cupreous hydrozincite. Usually in drusy incrustations. Altai ; Matlock, Derbyshire ; Spain ; Lancaster, Pa. OXYGEN COMPOUNDS. — CARBONATES. 411 ^ MALACHITE. Monoclinic. C= 88° 32', /A 1= 104° 28', i-i A -\-i = 118° 15', Zepliaro vich; c : 5 :« = 0-51155 : 1-2903 : 1. Coiunion form f. 750 ; also same with other terminal planes; also with i-i wanting ; also with i-i^ i-\ very large, making a rect- angular prism ; also with the vertical prism very short, as in f. 321. Crystals rarely simple. Twins : twinning- plane «-i, f . 750 ; often penetration twins, as in f. 321, 322, p. 99. Cleavage : basal, highly perfect ; clino- diagonal less distinct. Usually massive or inci"usting, with surface tubei-ose, botryoidal, or stalactitic, and struc- ture divergent ; often delicately compact fibrous, and banded in color ; frequently granular or earthy. H. = 3-5-4. G. = 3-7-4-01. Lustre of crystals adaman- tine, inclining to vitreous ; of fibrous varieties more or less silky ; often dull and earthy. Color bright green. Streak paler green. Translucent — subtranslucent — opaque. Fracture siibconchoidal, uneven. Comp. — Cu3C04+H20=CuC03 + H2Cu02=CaxboQ dioxide 199, copper oxide 719, watei R-2:=100. Pyr., etc. — In the closed tube blackens and yields water. B.B. fuses at 2, coloring the flame emerald-green ; on charcoal is reduced to metallic copper ; with the fluxes reacts like tenorite. Soluble in acids with effervescence. Diff. — Differs from other copper ores of a green color in its effervescence with acids. Obs. — Green malachite accompanies other ores of copper. Perfect crystals are quite rare. Occurs abundantly in the Urals ; at Chessy in France ; at Schwatz in the Tyrol ; in Cornwall and in Cumberland, England ; Sandlodge copper mine, Scotland ; Limerick, Waterford. and elsewhere, Ireland ; at Grimberg. near Siegen in Germany. At the copper mines of Nischne- TagUsk, belonging to M. Demidoff, a bed of malachite was opened which yielded many tons of malachite. Also in handsome masses at Bembe, on the west coast of Africa ; with the copper ores of Cuba ; Chili ; .\ ustralia. In N. Jersey, at New Brunswick. In Pennsylvania, near Morgantown, Berks County ; at Cornwall, Lebanon Co. ; at the Perkiomen and Phenixville lead mines. In Wisconsin, at the copper mines of Mineral Point, and elswhere. In California, at Hughes's mine in Calaveras Co. Green malachite admits of a high polish, and when in large nia.sses is cut into tables, snuff- boxes, vases, etc. Named from uaKaxhi maUows, in allusion to the green color. CUPBOCALCITE. — Massive. H. =3. G-.=8 90. Color vermUion-red. Analysis, Raymondi, CuoO 50-4o, CaO 2016, CO., 24 00, H,0 320, FeOa 0*60, i^lOs 020, MgO 097, SiOa 0-30= 99 86 . Occurs with a ferruginous calcite at the copper mines of Canza in Peru. AZURITE. Kupferlasur, Germ. Monoclinic. C = b7° 39' ; /A /= 99= 32', O M-l = 138° 41'; c:h:d = 1-039 : 1*181 : 1. O usually etriated parallel with tlie clinodiagonal. Cleavage: 24 rather perfect; i-i less distinct; / in traces. Also massive, and presenting imitative shapes, having a columnar composition ; also dull and earthy. II. = 3-5-4-25. G. = 3-5-3-831. Lustre vitreous, almost adamantine. Color various shades of azure-blue, passing into Berlin-blue. Streak blue, lighter than the color. Transparent — subtranslucent. Fracture conchoidal. Brittle. h^) ^^-r^XAi rj-'r^^-^ ^>t=^0 '^7 412 DESCRIPTIVE MINERALOGY. Comp. — Cu3Ci07+H.)0=2CuCOa + HaCuOa=Carbon dioxide 25-6, copper oxide 69*2, water 5 2=100. Pyr., etc. — Same as in malachite. Obs. — Occurs at Chessy, near Lyons, whence its name Chessy Copper. Also in Siberia ; at Moldava in the Banat ; at Wheal BuUer, near lledruth in Cornwall • also in Devonshire and Derbyshire. In Peiiii. , at the Perkiomen lead mine ; at Phenixville, in crystals ; at Cornwall. In WUt eoiiHin, near Mineral Point In Culifaruia, Calaveras Co., at Hughes's mine. According to Schrauf, who has given a crystallugraphic monograph of the species, the form \» closely related to that of epidote (Ber, Ak. Wien, July 3, I87i). BISMUTITE. Wismuthspath, Oerrn. In implanted acicular crystallizations (pseudomorphous) ; also incrusting or aniorplions ; pulverulent. Il.=4-4-5. G. = 6'86-6"909. Lustre vitreous, when pure; sometimes dull. Color white, mountain-green, aud dirty siskin-green ; occasionally etraw-yellow and yellowish-gray. Streak greenish-gray to colorless. Sub- transl ucunt — opaque. Brittle. Comp. — 2Bi6C30i8 f 9H2O, Ramm. (S. Carolina) = Carbon dioxide 6*.S8, bismuth oxido 89-75, water 3-87=100. Pyr., etc. — In the closed tube decrepitates and gives off water. B.B. fuses readily, and on charcoal is reduced to bismuth, and coats the coal with yellow bismuth oxide. Dissolves in nitric acid, with slight effervescence. Dissolves in hydrochloric acid, affording a deep yellow solution. Obs. — Bismutite occurs at Schneebsrg and Johanngeorgenstadt ; at Joachimsthal ; near Baden ; also in the gold district of Chesterfield, S. C. ; in Gaston Co., N. C, in yellowish- white concretions. LiEBiGiTE; VoGLiTE (Urankalk, Germ.). — Carbonates of uranium and calcium, from the decomposition of uraninite. Exact composition doubtful. Sciiiiockingerite is an oxycar- bonate of uranium (Schrauf). Orthorhombic. Occurs in six-sided tabular crystals. Joachims- thai Whewellite. — An oxalate of calcium. In minute monoclinic crystals on calcite. HUMBOLDTITE. — A hydrous oxalate of iron, 2FeC204 -t- 3aq. Compact; earthy. In brown- coal of Koloseruk, near Bilin; also in black shales at Kettle Point; in Bosanquet, Canada. MEiiiiiTE (Honigstein, Germ.), — Tetragonal. In octahedrons ; also massive, honey -yellow, reddish, or brownish, rarely white. AH. Cin0i2-+-18aq=Alumina 14'30, mellitic acid 40'30, water 45 34=100. Artern, Thuringia; Luschitz, Bohemia; Walchow, Morav^; Nertschiusk, etc. HTDROCAEBON COMPOUNDS. 413 VI. HYDROCARBON COMPOUNDS The Hydrogen-Carbon Compounds include (1) the simple hydrocarbons ; and (2) the oxygknated hydrocarbons. 1. The SIMPLE HYDRO CARBONS embrace : (a) The Marsli Gas series. General formula CnH2u^.2. Here belong the liquid navht/ias, the more volatile parts of petroleum ; also the butter-like solids scheererite and chrismatite. Petroleum. — Mineral oil. Kerosene. Bergol, Steinol, Erdol, G'erw. Petroleum is a thick to thin fluid. Color yellow or brown, or colorless ; translucent to transparent. The specific gravity varies from 0'7 to Oi). Chemically it consists essentially of carbon and hydrogen ; contain- ing several members of the naphtha group, as also the oils of the ethylene series, and the paraffins. The proportion of the latter constituents increases with the increase of the density or viscidity of the fluid. It grades insensibly into pittasphalt, and that into solid bitumen. Occurs in rocks or deposits of nearly all geological ages, from the Lower Silurian to the present epoch. It is associated most abundantly with argillaceous shales and sandstones, but is found also permeating limestones, giving them a bituminous odor, and rendering them Bometimes a considerable source of oil. From these oliferous shales and limestones the oil of ceu exudes, and api^ears floating on the streams or lakes of the region, or rises in oil springs. It also exists collected in subterranean cavities in certain rocks, whence it issues in jets or fountains whenever an outlet is made by boring. These cavities are situated mostly along the cour.se of gentle anticlinals in the rocks of the region ; and it is therefore probable, as has been suggested, that they originated for the most part in the displacements of the strata caused by the slight uplift. The oil which fills the cavities has ordinarily been derived from the subjacent rocks ; for the strata, in which the cavities exist, are frequently barren sandstones. Obtained in large quantities from the oil wells of Pennsylvania ; also found in eastern Vir- ginia, Kentucky, Ohio, Illinois, Michigan, and New York. In Canada, at several places ; in Boutheru California ; in Mexico ; Trinidad. Some well-known foreign localities are : Rangoon, Bunnah ; western shore of the Caspian Sea ; in Parma, Italy ; Sicily ; Galicia ; Tegernsee, Bavaria ; Hanover. (b) The Olefiant or Ethylene series. General formula Cnll2n. Here belong the pittoliuni group of liquids, ox jpittasphalU (mineral tar), and the jparajjiiis. Paraffin guoup. — Wax-like in consistence ; white and translucent. Sparingly soluble in alcohol, rather easily in ether, and crystallizing more or less perfectly from the solutions. G. about 0'8.5-0 -98. Melting point for the following species, o3^-90\ The different species varying in the value of «, vary also in boiling point, and other characters. Paraffins occur in the Pennsylvania petroleum, a freezing mixture reducing the tempera- ture being sufficient to separate it in crystals. Also in the naphtha of the Caspian, in Ran- goon tar, and many other liquid bitumens. It is a result of the destructive distillation of peat, bituminous coal, lignite, coaly or bituminous shales, most viscid bitumens, wood-tar, and many other substances. The name is from the Latin parum, little, and affinis, alluding to the feeble affinity for othei substances, or, in other words, its chemical inditi'erence. To the Paraffin (iroup belong: Uri'etiute.— Consistency of soft tallow. Melting point 39" C. Soluble in cold ether Urpeth Colliery, 414 DESCRIPTIVE MIKERALOOlf. Hatchettite. — In thin plates or massive. Color yellowish, or greenish- white ; blackene on exposure. Melting point 46" C. In the coal-measures of Glamorganshire ; Rossitz, Moravia. Ozocerite. — Like wax or spermaceti in appearance and consistency. G. =0'85-0'90. ODlorle.ss to white when pure ; often leek-green, yellowish, bro\\Tiish-yellow, brown. Trans lucent. Greasy to the touch. Fusing point 56' to 63" C. Occurs in beds of coal, or associ- ated liturainjus deposits ; that of Slanik, Moldavia, beneath a bed of bituminous clay shale ; in masses of sometimes 80 to 100 lbs., at the foot of the Carpathians, not far from beds of coal and salt; that of Boryslaw in a bituminous clay associated with calciferous beds in the formation of the Carpathians, in masses. The same compound has been obtained from mine- ral coal, peat, and petroleum, mineral tar, etc., by destructive distillation. Named from 6,'(j, smeUy and mipvc^ icnx, in allusion to the odor. Elateuite. — IMassive, .soft, elastic; often like india-rubber, though sometimes hard and brittle. It is found at Castleton in Derbj'shire, in the lead mine of Odin, along with lead ore and calcite, in compact reniform or fungoid masses, and is abundant. Also reported from St. Bernard's Well, Edinburgh, etc. Zietrisikite and Pybopissite belong here. (c) The Camphene Series. General Formula CnH2n_4. FichteI/ITE. — In white monoclinic crystals. Brittle. Solidifies at 36° 0. Soluble in ether. The mineral occurs in the form of shining scales, flat ci-ystals, and thin layers between the rings of growth and throughout the texture of pine wood (identical in species with the modem Pinus sylve)artly or wholly in ether ; commonly partly in alcohol. The more solid kinds graduate into the pittasphalts or mineral tar, and through these there is a gradation to petroleum. The Huid kinds change into the solid by the loss of a vaporizable portion on exposure, and also by a process of oxidation, which consists first in a loss of hydrogen, and finally in the oxygenation of a portion of the mas^s. Obs. — Asphaltum belongs to rocks of no particular age. The most abundant deposits are Buperficial. Bat these are generally, if not always, connected with rock deposits containing some kind of bituminous material or vegetable remains. Some of the noted localities of asphaltum are the region of the Dead Sea, or Lake Asphal- tites, on Trinidad; at various places in S. America, as at Caxitambo, Peru ; at Berengela, Peru, not far from Arica (S.) ; in California, near the coast of St. Barbara. Also in smaller quantities, sometimes disseminated through shale, and sandstone rocks, and occasionally lime- stones, or collected in cavities or seams in these rocks ; near Matlock, Derbyshire ; Poldice mine in Cornwall ; Val de Travers, Neuchatel ; impregnating dolomite on the island of Brazza in Dalmatia ; in the Caucasus ; in gneiss and mica schist in Sweden. The following substances are closely related to asphaltum, and, like it, are mixtures of un- determined carbohydrogens. Grauamite, Wurtz. — Resembles the preceding in its pitch-black, lustrous appearance; H. —2; G. =l'14o. Soluble moetly in oil of turpentine ; i^artly in ether, naphtha, or benzole ; not at all in alcohol ; wholly in chloroform and carbon disulphide. No action with alkalies or hot nitric or hydrochloric acid. Melts only imperfectly, and with a decomposition of the surface ; but in this state the interior may be drawn into long threads. Occurs in W. "Vir- ginia, about 20 m. in an air line S. of Parkersburg, filling a fissure (shrinkage fissure) in a sandstone of the Carboniferous formation ; and supposed to be, like the albertite, an inspis- sated and oxygenated petroleum. Albertite, liobb. — Differs from ordinary asphaltum in being only partially soluble in oil of turpentine, and in its very imperfect fusion when heated. It has H. =1-2; G.=-1'097; lustre brilliant, pitch-like ; color jet-black. Softens a little in boiling water ; in the flame of a candle shows incipient fusion. According to imperfect determinations, onlj' a trace soluble in alcohol ; 4 p. c. m ether ; 30 in oil of turpentine. Occurs filling an irregular fissure in rocks of the Subcarboniferous age (or Lower Carboniferous) in Nova Scotia, and is regarded as an inspissated and oxygenated petroleum. This and the above are very valuable in gas- making. PlAUZiTE. — An asphalt-like substance, remarkable for its high melting point, 315° C. It occurs slaty massive ; color brownish- or grefnish-black ; thin splinters colophonite-brown by transmitted light ; streak light brown, amber-brown ; H.=:l '5 ; G. = 1220; 118G, Kenngott. It comes from a bed of brown coal at Piauze, near Neustadt in Camipla ; on Mt. Chum, neai Tiiffer in Styria WoLT.ONOONorTE, SilUman. — Occurs in cubic blocks without lamination. Fracture brood oonchoidal. Color greenish- to brownish-black. Lustre resinous. In the tule does UDt melt, but decrepitates and gives off oil and gas ; jnelds by dry distillation 82 5 p. c. volatile matter Insoluble in ether or benzole. New South Wales. HTBROCARBON COMPOUNDS. 417 MINERAL COAL The distinguishing characters of Mineral Coal are as follows : Coinpac t massive, without crystalline structure or cleavage ; sometimes breaking with a degree of regularity, but from a jointed i-atlier than a cleavage struc- ture. Souietimes laminated ; often faintly and delicately banded, successive layers differino- slightly in lustre. H.=0-5-2-5. G. = l-l-80. Lustre dull to brilliant, and either earthy, resinous, or submetallic. Color black, giayish-black, brownish-black, and occasionally iridescent ; also sometimes dark brown. Opaque. Fracture conchoidal — uneven. Brittle ; rarely somewhat sectile. Without taste, except from impurities present. Insoluble or nearly so in alcohol, ether, naphtha, and benzole. Infusible to subfusible ; but often becoming a soft, pliant, oj" paste-like mass when heated. On distillation inost kinds afford more or less of oily and tarry substances, which are mixtures of hydrocar- bons and parafHn. Mineral coal is made up of different kinds of hydrocarbons, with perhaps in some cases free carbon. Var, — The variations depend partly (1) on the amount of the volatile ingredients afforded on destructive destination ; or (2) on the nature of these volatile compounds, for ingredients of similar composition may differ widely in volatility, etc. ; (3) on structure, lustre, and other physical charactei's. 1. Anthracite. H, =2-2-5. G. =1-32- 1 -7, Pennsylvania ; 1 SI. Rhode Island ; 1-2G-1 -36, South Wales. Lustre bright, often submetallic, iron black, and frequently iridescent. Frac- ture conchoidal. Volatile matter after drying 3 to 6 p. c. Burns with a feeble Hame of a pale color. The anthracites of Pennsylvania contain ordinarily Si) to \)o per cent, of carbon ; those of South Wales, 88 to 95 ; of France, 80 to 83 ; of Saxonj', 81 ; of southern Russia, some- times 94 per cent. Anthracite graduates into bituminous coal, becoming less hard, and con- taining more volatile matter ; and an intermediate variety is called free-huriung anthracite. Bituminous Coals (Steinkohie pt, , Genii.\ Under the head of Bituminous Coals, a number of kinds are included which differ strikingly in the action of heat, and which there- fore are of unlike const'tution. They have the common characteristic of burning in the iire with a yellow, smoky tlame, and giving out on distillation hydrocarbon oils or tar, and hence the name bitumi/iou.s. The ordinnri/ bituminous coals contain from 5 to 15 p. c. (rarely IG or 17) of oxygen (ash excluded) ; while the so-called brown coal or Ugnits contains from 20 to 36 p. c, after the expulsion, lA lOi) C. , of 15 to 36 p. c. of water. The amount of hydrogen in each is from 4 to 7 p. c. Both have usually a bright, pitchy, greasy lustre (whence often called Pcchkohle in German), a firm compact texture, are rather fragile compared with anthra- cite, and have G. =1'14-1"40. The brown coals have often a brownish-black color, whence the name, and more oxygen, but in these respects and others they shade into ordinary bitu- minous coals. The ordinarv bituminous coal of Pennsylvania has G.=l •26-1*37 ; of New- castle, England, 1-27; of Scotland. 1-27-1 -32; of France, 1*2-1 '33; of Belgium, 1-27-1-3. The most prominent kinds are the following: 2 Caking C »ai-. A bitummous coal wiiich softens and becomes pasty or semi-viscid in the fire. This softening takes place at the temperature of incipient decomposition, and ia attended with the escape of bubbles of gas. On increasing the heat, the volatile products which result from the ultimate decomposition of the softened mass are driven off, and a coherent, grayish-black, cellular, or fritted mass (coke) is left. Aniount of coke left (or part not volatile) varies from 5Q to 85 p. c. Bj/rrlte is from Middle Park, Colorado. 3. Non-Caking Coal. Like the preceding in all external characters, aad often in ultimate composition ; but burning freely without softening or any appearance of incipient fusion. 4. Cannel Coal (Parrot Coal). A variety of bituminous coal, and of ten caking ; but dif- fering from the preceding in texture, and to some extent in composition, as shown by ita products on distillation. It is compact, with little or no lustre, and without any appearance of a banded structure; and it breaks with a conchoidal fracture and smooth surfaces; coloi dull black or grayish- black. On distillation it affords, after drying, 40 to 6() ol volatile mat- ter, and the material volatilized includes a large proportion of burning and lubricating oils, 27 413 DESCRIPTIVE MINERALOGr. mnch larger than the above kinds of bituminous coal ; whence it is extensively used for the manufacture of such oils. It graduates into oil-producing coaly shales, the more compact of which it much resembles. 5. TdUB.vxiTE. A variety of cannel coal of a dark brown color, yellowish streak, without lustre, having a subconchoidal fracture; H. =2-25 ; G. = 1-17-1 -2. Yields over 00 p. c. of volatile matter, and is used for the production of burning and lubricating oils, paraffin, illu- minating gas. From Torbane Hill, near Bathgate in Linlithgowshire, Scotland. Also called Boghend Uminel. is. Bkown Co.\l (Brauukohle Genu.. Pecbkoble pt. Givm., Lignite\ The prominent characteristics of brown coal have already been mentioned. They are non-caking, but afford a large proportion of volatile matter They are sometimes pitch-black (whence Peohkohle pt. (?«'m.), but often rather dull and brownish-hlack. G. = ri5-1 ■;> ; sometirnes higher from impurities. It is occasionally somewhat lamellar in structure. Brown coal is often called lignite. But this term is sometimes restricted to masses of coal which still retain the form of the original wood. Jit is a black variety of brown coal, compact in texture, and taking a good polish, whence its use in jewehy. 7. Earthy Buown Co.\i, (Erdige Brnunkohle) is a brown friable material, sometimes form- ing layers in beds of brown coal. But it is in general not a true coal, a considerable part of it being soluble in ether and benzole, and often even in alcohol; besides affording largely of oils and paraffin on distillation. Comp. — Most mineral coal consists mainly, as the best chemists now hold, of oxygenated hydrocdvbotis. Besides oxygenated hydrocarbons, there may also be present simple hydrocar- bons (that is. containing no oxygen). Sulphur is present in nearly all coals. It is supposed to be usually combined with iron, and when the coal affords a 7'ed ash on burning, there is reason for believing this true. But Percy mentions a coal from Xew Zealand (anal. 18) which gave a peculiarly white ash, although containing 2 to 3 p. c. of sulphur, a fact showing that it is present not as a sulphide of iron, but as a constituent of an organic compound. The discovery by Church of a rcain containing sulphur (see T.\smasite, p. 415), gives reason for inferring that it may exist in this coal in that state, although its presence as a constituent of other organic compounds is quite possible. The chemical relations of the different kinds of coals will be understood from the follow- ing analyses : Carbon. Hydrogen. Oxvgen. ^Nitrogen. Sulphur. Ash. 1. Anthracite, S. Wales 92-56 3 33 2-53 1-58 3. Caking Coal, Northumberland 78-69 600 10-07 237 1-51 1-36 3. Non-Caking Coal. Zwickau 8025 401 10 98 0-49 2-99 1-57 4. Cannel Coal, Wigan 80-07 5-53 810 2-12 ISO 2-70 5. Torbanite. Torbane HUl 64-02 8 90 5 66 0-55 50 20 32 6. Bro^\Ti Coal, Meissen, Sax. 58-90 5-36 21-63 6 61 7 50 Coal occurs in beds, inter.stratified with shales, sandstones, and conglomerates, and some- times limestones, forming distinct layers, which vary from a fraction of an inch to 30 feet or more in thickness. In the United States, the anthracites occur east of the Alleghany range, in rocks that have undergone great contortions and fracturings, while the bituminous are found farther west, in rocks that have been less disturbed ; and this fact and other observa- tions have led some geologists to the view that the anthracites have lost their bitumen by the action of heat. The origin, of coal is mainly vegetable, though animal life has contributed somewhat to the result. The beds were once beds of vegetation, analogous, in most respects, in mode of formation to the psat beds of modem times, yet in mode of burial often of a very different character. This vegetable origin is proved not only by the occurrence of the leaves, stems, and logs of plants in the coal, but also by the presence throughout its te.xture, in many cases, of the forms of the onginal fibres; also by the direct observation that peat is a transition .state between unaltered vegetable dobris and brown coal, being sometimes found passing completely into true brown coal. Peat differs from true coal in want of homo- geneit}', it visibly containing vegetable fibres only partially altered ; and wherever changed to a fine-textured homogeneous material, even though hardly consolidated, it may be true brown coal. Extensive beds of mineral coal occur in Great Britain, covering 11.859 square miles; in France about 1.719 sq. m. ; in Spain about 3,408 sq. m. ; in Belgium 518 sq. m. ; in Nether- lands, Prussia. Bavaria, Austria, northern Italy, Silesia, Spain, Russia on the south near the Azof, and also in the Altai. It is found in Asia, abundantly in China, etc.. etc. In the United States there are fo-ar separate coal areas. One of these areas, the Appala- chian coal field, commences on the north, in Pennsylvania and southeastern Ohio, and sweep HYDROCARBON COMPOUNDS. 419 Ing south over western Virginia and eastern Kentucky and Tennessee to the west of the Appalachians, or partly involved in their ridges, it continues to Alabama, near Tuscaloosa, where a bed of coal has been opened. It has been estimated to cover 00,000 sq. m. A sec- ond coal area (the Illinois) lies adjoining the Mississippi, and covers the larger part of Illinois, though much broken into patches, and a small northwest part of Kentucky. A third covers the central portion of Michigan, not far from 5,000 sq. m. in area. Besides these, there ia a smaller coal\egion (a fourth) in Rhode Island. The total area of workable coal measures in the United States is about 123,000 sq. m. Out of the borders of the United States, on the northeast, commences a fifth coal area, that of Nova Scotia and New Brunswick, which covers, in connection with that of Newfoundland, 18,000 sq. m. The mines of western Pennsylvania, those of the States west, and those of Cumberland or Fro.stburg, Maryland, Richmond or Chesterfield, Va., and other mines south, are bituminous. Those of eastern Pennsylvania constituting several detached areas— one, the Schuylkill coal field— another, the Wyoming coal field— those of Rhode Island and Massachusetts, and tome patches in Virginia, are anthracites. Cancel coal is found near Greensburg. Beaver Co., Pa., in Kenawha Co , Va.. at Peytona etc. ; also in Kentucky, Ohio, Dlinois, Missouri, and Indiana ; but part of the so-called cannel is a coaly shale. Brown coal comes from coal beds more recent than those of the Carboniferous age. But much of this more recent coal is not distinguishaljle from other bituminous coals. The coal of Richmond, Virginia, is supposed to be of the Liassic or Triassic era ; the coal of Brora, in Sutherland, and of Gristhorpe, Yorkshire, is Oolitic in age. Cretaceous coal occurs on Van- couver Island, and Cretaceous and Tertiary coal in many places over the Rocky Mountains, where a " Lignitic formation" is very widely distributed. PART in.— DESCRIPTIVE MINERALOGY. SUPPLEMENTAEY CHAPTER.* Abriachanite, Hoddle. — A soft blue clay-like substance, filling seams and cavities in granite. Probably neai- crocidolite (p. 29S) in composition. From the Abiiachan district near Loch Ness, Scotland. Adamite p. 373. — Occurs in colorless to deep green crystals, and in iiiammillary groups, at the ancient mines, recently reopened, at Laurium, Greece. Aglaite. — Same as cymatolite ; that is, an alteration product of spodumene, consisting of an intimate mixture of albite and museovite. From Goshen, Mass. Alaskaite, Kfinig.— Massive. G. = 6-878. Lustre metallic. Color whitish lead-gray. Composition probably (Ag,.,Cuo,Pb)S + BioSa. Analysis after deducting impurities. S 17-63, Bi 50-1)7, Sb 0-62, Pb 11 79, Ag 8-74, Cu 3-40, "Zn 0-79 = 100. From the Alaska mine, Poughkeepsie Gulch, Colorado. Silbervvismuthglanz of Rammelsberg, from Moro- coeha, Peru, is pure AgoS + BioSa. Albite. p. 323. — Has been made artificially, identical in form and composition with natu- ral crystals, by Ilautefcuille. Ajiblygonite, p. 869. — Penfield has analyzed specimens from Penig, Montebras, Hebron and Auburn, Me., Branchville, Ct. (including •' hebronite "' and '• montebrasite "). Ho shows that, while the varieties vary from F 11-26, HjO 1-75 in one sample to F 1-75, IIo06-6I, in another, they all conform to the general formula: AIjP-jOb + 2R(F,0H), differing only in the extent to which the hydroxyl replaces the fluorine. Amphibole, p. 29(). — A variety containing only 09 p.c. MgO, has been called hergamas- kite by Lucchetti Occurs in a hornblende porpliyry. Monte Altino, Bergamo, Italy. Phddcfinite (Bertels) is a chloritic alteration product from a rock called isenite. is''assau, Germany. Analcite, p. 343. — On the crystalline system, see p. 189. Picrcmalcite, of Bechi. is identical with ordinary analcite, containing only a trace of magnesia, according to Bamberger. Animikite, Wurtz. — An impure massive mineral supposed to be a silver antimonide (Sb 11-18, Ag 77-58). Silver Islet, Lake Superior. Anner()DITE, Brogger. — A rare columbate, almost identical with samarskitc in composi- tion, but in form very near columbite. From a pegmatite vein at Anaerod, near Moss, Norway. Apatite, n. 364. — Large deposits of apatite, affording sometimes gigantic crystals, and sometimes mined for commercial purposes, occur in Ottawa County, (Quebec, Canada ; also large crystals, with zircon, titanite and amphibole in Renfrew County, Ontario, and else- where ; there are similar deposits at Kjrirrestad, Bamle, Norway. A variety from San Roque. Argentine Republic, containing 0-7 p.c. MnO. has been called mangfmctpatite by Siewert. Penfield found 106 p.c. MnO in a bluish-green specimen from Branchville, Ct. Pseudo-hexagonal, Mallard, see p. 187. * For fnllcr descriptions of new species, references to original papers, etc., see Appendix III. (1882), Sj'stem of Mineralogy. 420 DESCRIPTIVE MINERALOGY. 421 Apophyllite, p. 340.— Pseudo-tetragonal (monoclinic), according to Mallard and Rumpf, but the correctness of their conclusions is doubtful ; see p. 185 et seq. Aragonite, p. 405.— A variety from the Austin mine, Wythe Co., Va., afforded 7'29 p,c. PbCOa. Arctolite, Blomstrand.— a doubtful silicate, composition near prehnite, prismatic angle near hornblende, llvitholm, near Spitzbergen. Arequipite, Raimondi.— a honey-yellow compact substance, supposed to be a silico-anti- monate of lead, but probably a mixture. Victoria mine. Province of Arequipa, Peru. Arfvedsonite, p. 298. — Occurs with zircon and astrophyllite in El Paso Co., Colorado. Arrhenite, Nordenskiold. — A silico-tantalate of yttrium, erbium, etc., resembling feld- spar in appearance. Probably an uncertain decomposition product, Ytterby, Sweden. Arsenaegentite, Hannay. — An uncertain silver arsenide of doubtful source. ASMANITE, p. 288. — According to Weisbach and v. Lasaulx, identical with tridymite ; observed in tne meteoric iron of Rittersgriin, Saxony. Astrophyllite, p. 813. — Referred to the triclinic system by Brogger ; properly a mem- ber of the pyroxene group, not one of the true micas. Occurs with arfvedsonite and zircon in El Paso Co., Colorado. Ateltne (or atelite\ Scacchi.— An alteration product of tenorite at Vesuvius ; near ata- camite in composition. Atopite, Nordenskiold. — In isometric octahedrons. H. = 5'5-6, G. = 5 03. Color yellow to brown. Composition essentially CasSb^O; (near roraeite). Imbedded in hedyphane at Langban, Sweden. Autunite, p. 379.— Monoclinic (or triclmic), according to Brezina. Balvraidite, Heddle.— a doubtful substance having a saccharoidal structure, and pale purpli.sh- brown color. G. = 2-9. An analysis gave, SiO^ 46 04, AI2O3 20-11. Fe-.Os 2-52, MnO 0-79, MgO 8-30, CaO 13-47, Na,0 272, K,0 1-36, H^O 4-71 = 10002. In limestone at Balvraid, Inverness-shire, Scotland. Barcejtite, Mallet. — An uncertain alteration product of livingstonite, massive, earthy, color dark gray. G. = 5-343. Iluitzuco, Guerrero, Mexico. Barylite, Blomstrand. —In groups of prismatic crystals. Two distinct cleavages (84°). H. = 7. G. = 403. White. BB. infusible. A silicate of aluminum and barium (46 p.c. BaO). In limestone at Langban, Sweden. Beeoerite, K()nig. — In elongated isometric crystals. Cleavage cubic. G. — 7'273. Color gray. Lustre metallic. Composition, 6PbS + Bi.Sa = S 14-78, Bi 2136, Pi) 63-84 = 100. From the Baltic Lode, Park Co., Colorado. Beryl, p, 299. — Pseudo-hexagonal, according to Mallard, see p. 186. A variety in short prismatic to tabular crystals has been called rosterite by Grattarola, Locality, Elba. Found (W. E. Hidden) in fine crystals of large size (to 10 inches in length), and emerald color, in Alexander Co., N. C, also in highly modified crystals of pale green color. Berzeliite. — This arsenate from Langban, Sweden, is isometric according to Sjogren ; honey to suliihur yellow, lustre resinous. Lindgren regards the ortho-arsenate of calcium and magnesium, anisotrope, of the same locality, as distinct, and says that earlier descrip- tions of berzeliite belong to it. 422 DESCRIPTIVE MINERALOGY. Bhreckite (or Vreekite), Heddle. — A doubtful soft apple-green substance, coating quartz crystals. A hydrous silicate of aluuiina, iron, magnesia and lime. From the hill Ben Bhreck, Sutherland, Scotland. BiSMCTOSPH/ERlTE, Weisbach. — In spherical forms, with concentric, fine fibrous radiated structure. Kegarded as an anhydrous bismuth carbonate. From Neustiidtel, Schnceberg, Saxony. Blomstrandite, Lindstrom. — A columbo-titanate of uranium, allied to samarskite. Prom Nohl, Sweden. BoLiviTE. Domeyko. — An alteration product of bismuthinite, probably a mechanical mixture of BioOa and BioSs. Mines of Tazna, Province of Choroloque, Bolivia. BoEAClTE, p. 381.— On the crystalline system, see p. 189. BowLiNGiTE, Hannay. — A soft, soapy, green substance, containing silica, alumina, iron, magnesia, lime, water ; doubtless heterogeneous. Bowling on the Clyde, Scotland. Bravaisite, Mallard. — In fine crystalline fibres, of a grayish color, forming layers in the coal schists at Noyant. Allier Dep't. Prance. G. = 2-6. Analysis, SiOa 51-4, AI..O3 18 9, Fe^Oa 4 0, CaO 2-(», MgO 3-3, K.,0 6-5, HnO 18 3 = 99-4. Brooktte, p. 277. — In Mallard's view, brookite, rutile and oetahedrite are all monoclinic, having the same primitive form, but differing in the way in which the individuals are grouped, see p. 186. Brucite. p. 281. — Manganhrucite figelstrum) is a manganesian variety of brucite (1416 MnO) from the manganese mines of the Jakobsberg, Werraland, Sweden. In fine granular form with hausmannite in calcite. Eisenb)nicUr. Santlberger. — A doubtful substance resulting from the alteration of bru. cite. Sieberlehn near Freiberg. Cabrerite. — Occurs in crystals (isomorphous with erythrite) at the zinc mines of Lau- rium, Greece An analysis by Damour corresponds to NisAsoOn -|-8 aq. Calamixe, p. 329. — According to Groth, the formula should be written HoZnoSiOs. Calaverite. p. 249. — Occurs at the Keystone and Mountain Lion mines, Colorado. Com- position (Genth) : (Au,Ag,Teo, with Au : Ag = 7 : 1. H. = 2-5. G. = 9-043. Cancrixite, p 317. — An original species (Rauff, Koch), and not an alteration product of nephelite, the carbon dioxide being essential and not due to calcite. Caryinite, Lundstrom. — Massive, monoclinic ; two cleavages (130"). H. = 3-3'5. G. = 4-25. Color, brown. Composition, RjAs^Of, with R = Pb,Mn,Ca,Mg. Occurs with calcite and hausmannite at Ldngban, Sweden. Chabazfte, p. 344. — Triclinic, according to Becke, the crystals being complex twins of several individuals. Chalcomexite. Des Cloizeaus and Damour. —Monoclinic. / a I~ 108" 20'. a i-i = 89° 9'. G. = 3-76. Color, bright blue. Composition. CuSeOa + 2 aq, or a copper sele- nite. From the Cerro de Cacheuta, Mendoza, Argentine Republic. Chalcopyrite, p. 244. —Found well crystallized, often coated with crystals of tetrahe- drite in parallel position, near Central City, Gilpin Co , Colorado. Childrenite, p. 377.— Formula, as shown bv Penfield, RoAloP^Om + 4HoO. or AUPjO? + 2RH,0 + 2 an. with R = Fe principally, also Mn. This requires: P,0» 30-80, AlO, 22-31 FeO 26-37, MnO 4-87, H^O 15-65. DESCRIPTIVE MINERALOGY. 423 A mineral closely related to childrenite has been called eosphorite by Brash and E S- Dana. Urthorhombic. In prismatic crystals (see tig.), near chil- drenite. /Ai= 104' 19' : p /\ p (I r^l) --^ 1JJ3° 33' (front), = 118' 58' (side). Here 7, and a [i-'i] = 2-/ and of childrenite. Also mass- ive, cleavable to compact. Cleavage parallel a(;i-'i) nearly perfect. H. = 5. G. = 3 11-3 145. Lustre vitreous to sub-resinous, also greasy. Color rose pink, yellowish, colorless, when compact various ."^hades of white. Streak white. Transparent to translucent. (Jeneral formula like childrenite (see above), but witii much man- ganese and little iron dO : :;)• Percentage composition: P-jO^ 30-93, AlsOa 2- -35, MnO 23-80, FeO 7-24. HoU 15-68 = 100. B. B. in the forceps cracks opens, sprouts and whitens, colors the flame pale green and fuses at 4 to a black magnetic mass. Keacts for manga- nese and iron ; is soluble in acids. Occurs with other manganesian phosphates in a vein of pegmatite at Branchville, Conn. a Chlorallumixite, Scacchi. — Hydrous aluminum chloride from Vesuvius. Chloromagnesite. Scacchi. — Hydrous magnesium chloride from Vesttxdus. Bischofite /Ochsenius and Pfeiffer) from Leopoldshall, Prussia, has the composition MgCL -i- 6 aq. Crystalline, massive, foliated or fibrous. Colv Also from the Skopi, Switzerland, in transparent crystals. DESCRIPTIVE MINERALOGY. 425 Davreuxtte, de Koninek. — In ae^gregates of minute acicular crystals. Color white, with tinge of red. Calculated composition : SiO. 46-89. Al.Os 40-19, MnO 6-93, ^NlgO 1-30, HjO 4-69 = 100. Occurs in quartz veins in the Ardennes schists at Ottre, Belgium. Da-«'soxite. p. 410. — Occurs (C'haper) in the province of Siena, Pian (astagnaio. Tuscany. Analvsis gave Friedel : (i) CO-j 29-09, AI0O3 35 89, Na,0 19-13, H,0 12-00, WgO 1-39, CaO 0-4-.>. Delessite, p. 3")6. — More or less related to the chloritic delessite are : Subdelessife from the Thuringer Walcl ; HuUite, Cammoney Hill, near Belfast, Ireland. Bescloizite. p. 367.— Occurs in the Sierra dc Cordoba, Argentine Republic : perhaps also in Arizona. Composition of South American mineral (Rammelsbcrg) R3V..0,* + RHjOn, ■with R ^ Pb (56 p.c. ■, Zn ( 17 p.e.) Bracl-ehnschik from C ordoba, Argentine Republic, occurs in small striated crystals. Color black, i omposition perhaps RaV^O^ + H...0, -with R = Pb : Fe : Mn = 4:1 : 1. Destixezite, Forir and Jorissen. — An iron phosphate from Argenteau, Belgium ; occurs in yellowish white earthy masses. Diamond, p. 228. — Has been made artificially, in the form of a fine sand, by J. B. Hannay. DiCKiNSONiTE. G. J. Brush and E. S. Dana. — Monoclinic. pscudo-rhombohedral, (5= 61° 30 . c/\a - 118" 30', cap - 118" 52', c/\s = 97" 58' : c ^0,p=l,s = 2, .v = - 3-/. Com- monly foliated to micaceous. Cleavage basal perfect. H. = 3-5-4. G. = 3-338-3-343. Lustre vitreous, on c pearly. Color various shades of green. Composition 4R3P'>0^ + 3aq. with R = Mn,Fe,' a.Na,, requiring: P,05 40-a5, FeO 12-69. :Mn0 25-04, CaO 11-85, XaoO 6-50, HjO 3-81=10'. Occurs with eosphorite, triploidite, etc., in pegmatite at Branchvil'.e, Conn. DiETRiCHiTE, V. Schr<)ckinger. — A zinc-iron-manganese alum, related to mendozite, etc. A recent formation at Felsobanya, Transylvania. DoppLERiTE. p. 415. —A black gelatinous hv-drocarbon from a stratum of muck below a peat bed at Scranton, Penn., is called by H. C. Lewis phytocoliite ; empirical formula C,„H,,0,e. DoUGLASiTE, Ochsenius, Precht.— From Douglasshall, formula, 2KCl,FeCl2,2H20. DvMORTiERiTE. Damour, Bertrand. — In minute prismatic crvstals of a cobalt blue color, imbedded in gneiss. Analysis (Damour) : SiO. 29-85, ALOs 6602, Fe.Os 1-01, MgO 0-45, ign. 225 = 99-58 ; near andalusite. From the gneiss at Chaponost, near Lyons, France. DuPORTHiTE, Collins. — An asbestiform mineral filling fissures in serpentine. Color green- ish to brownish gray. Contains silica, alumina, iron, magnesia, and water. Duporth, St. Austell, Cornwall. DiJRrELDTiTE, Raimoudi. — Massive, indistinctlv fibrous. Color light gray. Metallic. Composition 3RS + Sb-^Ss (if the results of an analysis after deducting 31 p.c. gangue can be trusted^, with R = Pb,Ago,Mn, also Fe,Cuo. From the Irismachay mine, Anquimarea, Peru. Dysanalyte. Knop. — The perofskite of the Kaiserstuhl is, according to Knop, a new columbo-titanate of calcium and iron (with also Ce,Na). Eggonite, Schrauf. — In minute, grayish-brown crystals (trielinic) near barite in habit. Supposed to be a cadmium silicate. Occurs with calamine and smithsonite at Altenberg. Ekdemite, Xordenskiold. — Massive, coarsely granular, also incrusting. Cleavage basal. H. = 2-5-3. G. = 7-14. Color bright vellow to green Composition PbsAs 0^ -1- 2PbCli - As,O.,10-59, PbO 59-67, CI 7-58, Pb 22-16 = 100. .Found at Langban, Sweden. 426 DESCRIPTIVE MINERALOGY. Eleoxorite, Nios. — Monoelinic ; often in ("Irusesand in radiated crusts. Cleavage ortho- diagonal. II. = 8-4. Lustre vitreous. Color red brown to dark hyacinth red. Streak yellow. Coinposition (Strens?) 2Fc..l*...0„ ^ FeoH,;0n + 5 acj. From the Elconore mine on the Dtinshers-, near Gicssen, and the Rothlaufchen mine near Waldgirmes. Perhaps identiciU with the iron phosphate beraunite from Benigna, Bohemia. Ellonite, Hcddle. — Imjiure silicate of magnesia, containing SiOo. Aberdeenshire, Scotland. In gneiss near Ellon, Elroquite, Shepard. — A heterogeneous substance containing silica, alumina, iron oxide, ■water and (as an impurity) 32 p.c. PjOo. Island of Elroque, Caribbean Sea. Enysite, Collins. — A bluish-green stalagnutic substance consisting of aluminum hydrate, basic copper sulphate, caleite, etc. St. Agnes, Cornwall. Epistilbite, p. identical. 347. — Monoelinic, Des Cloizeaux. Puradilhite and reissite are probably Epsomite, p. 394. — Reichardtite (Krause) is a massive variety from Stassfurt and Leo- poldshali. Ebilite, Lewis. — Aeicular, wool-like crystals of unknown nature occurring in a cavity in the quartz from Herkimer Co., N. Y. Eriochalcite, Seacehi. — Copper chloride from Vesuvius. Erythrozincite, Damour. — In thin crystalline plates. Color red. Perhaps (Des Cloi- zeaux) a manganesian variety of wurtzite. EucLASE, p. 333. — Found in good crystals in the Tyrol, from the Hohe Tauern, perhaps at Rauris. EucRASiTE, PaijkuU. — A mineral from Brevig, Norway, near thorite. EucRYPTiTE, G. J. Brush and E. S. Dana. — Hexag- onal. In regularly arranged crystals imbedded in albite (like graphic granite, see fig.) both of which have resulted from the alteration of spodumene. G. = 2'667. Composition LioAl.Si.OH = SiOo 47-51, Al.Oa 40-61, LioO 11-88 =r 100. Branchville, Conn. EULYTITE, p. to Bertrand. 302. — Pseudo rhombohedral according EusYNCHiTEis (Rammelsberg) 4Pb3Vn08 -i- SZuaVjOs. Ariioxene is 2(Pb,Zn);,V,0„ + (Pb,Zn):,As2 0,. TrifocJwrite (Frenzel) is related, composition RaVaOg, with R = Pb (54 p.c), Cu (7 p.c), Zn (11 p.c). Lo- cality uncertain. Fairfieldtte. G. J. Brush and E. S. Dana. — Triclinic Foliated or lamellar, crystalline; also in radiating masses, curved foliated or fibrous. Cleavage brachydiagonal perfect. Lustre pearly to subadamantine. Color white to pale straw yellow. Transparent. Com- position R:,P.O. + "aq, with R = Ca : (Mn + Fe) = 2 : 1. This requires : P.O., 39-80. FeO 6-64. MnO 13-10. CaO 30-99, H,0 997 = 100. Occurs with other manganesian phosphates at Branchville, Conn. Lenromangamte (Sandberger) from Rabenstein, Bavaria, may be identical ; not yet described. Feldspar Group.— Schuster has shown that in the series of triclinic feldspars there is DESCRIPTIVE minj:kalogy. 427 in optical relations the same gradual transition from the one extreme (alljite'; to the other (anorthite) as exists in composition. Tiius, he finds tiiat the directions of light-extinction, as observed on the basal and cliiiodiagonal sections, the position of tlie axes of elasticity, the dispersion of the axes, and the axial angle all show tins gradual change in the same direction. These results confirm tlie accepted view of Tscherraak that the intermediate triclinie feldspars are to be regarded as isoraorphous mixtures of albite and anorthite in varying proportions ; moreover, they explain the apparent difficulties raised by the obser- vations of Des Cioizeaux {p. 8l!»). The angles given on p. 320 are then true only in special cases, since in the varieties varying in composition these values will also vary. The values for angles (given by Schuster) made by tlie extinction-directions with and i-i are as follows : With With i-l Albite +4° to +3° -f 18° Varieties between Albite ) , oo . ho mo and Oligoclase f + ^ *^ +1 +^^ Oligoclase +2° to -i- 1° +3° to -f 2° Andesite - 1" to — 2° — 4° to — 6° Labradorite —4° to —5° —17° Varieties between Labra- ) ir-o <_ -,r,o one, dorite and Anorthite.... f -^^ *« -^^ - 2^ Anorthite -38° -40° Fekgusonite, p. 3fi2. — New localities : Rockport, Mass. (J. L. Smith) ; Burke Co., N. C. (Hidden) ; Mitchell Co., N. C. (Shepard). Ferrotellurite, Gcnth. — In delicate radiating crystalline tufts of a yellow color. Per- haps an iron tcllurate. Keystone mine. Magnolia District, Colorado. FiLLOWiTE, G. J. Brush and E. S. Dana. — Monoclinic ; pseudo-rhombohedral. Gener- ally in granular crystalline masses. H. = 45. G. = 3'43. Lustre subresinous to greasy. Color wax vellow, vellowish to reddish brown. Composition SRsP. 0^ + aq, with R = Mn, Fe, Ca, Na^ ; requiring : P.,0, 40-19, FeO 680, MnO 4019, CaO 5-28, NaoG 5 84, H^O 1-70 = 100. Occurs with other manganesian phosphates in pegmatite at Branchville, Conn. Fluorite, p. 263. — Pseudo-isometric, according to Mallard ; see p. 186. FoRESiTE, p. 347. — Probably identical with stilbite. Franklaxdite, Reynolds. — Near ulexite. Massive. White. G. = 1*65. Composition Na4CanBi20...j, loHoO. Tarapaca, Peru. Freyalite, Esmark, Damoiir. — A silicate of cerium, thorium, etc. G. = 4-06-4*17, Color brown. From Brevig, Norway. Gadolinitf, p. 309. — Contains the new earth ytterbium (Marignae), also scandium (Cleve) Galexobtsmxjtite, H.Sjogren.— Massive, compact. H. = 3-4. G. =: 6-88. Lustre me, tallic. Color tin white. Streak grayish black. Composition PbBioS4 or PbS + BioSs, requiring, S 16-95, Bi 55-62, Pb 27-43 = 100. Occurs with bismutite at the Kogrufva, Nordmark, Sweden. Ganomalite, Nordenskiold.— Massive. H. =4. G. = 4-98. Lustre greasy. Colorless to white or whitish gray. Transparent. Composition (Pb,Mn)Si03 ; analvsis (Lind- strom : SiO, 3455, PbO" 34-89, MnO 2001, CaO 4-89, MgO 3-68, alk., ign. r88=99-58. Occurs with tephroite, native lead, etc., at Langban, Sweden. Garnet, p. 302. — Pseudo-isometric, according to Mallard and Bertrand, see p. 186. Nearly colorless garnets occur at Hull, Canada ; others containing 5 p.c. Cr20a at Wakefield, Quebec. Large perfect crystals in mica schist near Fort Wrangell, Alaska. Garnierite, p. 351. — An allied hydrated silicate of magnesium and nickel has been found in Southern Oregon, at Piney Mountain, Cow Creek, Douglas Coxrnty. 428 DESCKIPTIYE MINERALOGY. GiNiLSiTE, Fischer. — A doubtful silicate from the Ginilsalp, Graubiinden, Switzerland. QisMONDiTE, p. 341. — Tricliuic, complex twins, according to Schrauf and v. Lasaulx. GuANAjUATiTE, Femandez, 1873. — The same mineral as that afterward called frenzelite (p. 223). Composition (Mallet), BinScs, with a little Se replaced by S. ISilaonite is a mechanical mixture of this mineral and native bismuth. GuNXTSoxiTE, Clarke and Periy (Am. Chem. Journ., iv., 140). — A massive substance, of a deep purple color, mixed with caleite. An analysis, after deducting 12-75 CaCUa. yielded CaPo 74-89, CaO 1144, SiOo 6-87, AI0O3 595, Na,0 0-85 = 100. Probably an impure fiuorite ; perhaps altered ; certainly not a homogeneous mineral. GuEJARiTE, Curaenge. — Orthorhombic ; in prismatic crystals, form near that of chalco- stibite. H. = 3-5. G. =503. Color steel gray. Composition CuoSbiS; or CuoS + 2Sb2S3. From the copper mines in the district of Guejar, Andalusia. GuMMiTE. — This decomposition product of uraninite occurs in considerable masses at the Flat Rock mine, Mitchell Co., N. C. Gyrolite, p. 328. — Tohermorite of Heddle, is near gyrolite and okenite. Massive. Color pinkish white. G. = 2-423. Analysis : SiO, 46-62, AI0O3 3-99, F^Og 066, FeO 1-08, CaO 33-98, K,0 0-57, NajO 089, HoO 1211 - 99-81. Filling cavities in rocks near Tobermory, Island of Mull. Halloysite, p. 352. — Indianaite of Cox, is a white porcelain clay, useful in the arts, occurring in considerable beds in Lawrence Co., Indiana. Hannayite, vom Rath. — In triclinic prismatic crystals. G. = 1-893. Composition H4(NH4)Mg3P40ir, + 8 aq. Occurs in guano of the Skipton Caves, Victoria. Hatchettolite, J.L. Smith. — Isometric, habit octahedral. H. = 5. G. = 4-77^90. Lustre resinous. Color yellowish brown. Translucent. Fracture conchoidal. A columbo-tan- talate of uranium and calcium, containing 5 p.c. water ; closely related to pyrochlore. With samarskite in the mica mines of Mitchell Co., N. C. HAYESiira. — According toN. H. Darton, this borate occurs sparingly with datolite and cal- eite at Bergen Hill, N. J. Hedyphane, p. 367. — A variety from Langban contains (Lindstrom) 8 p.c. BaO. Mono- clinic (Des Cloizeaux), and perhaps isomorphous with caryinite, p. 422 ; this would sepa- rate it from mimetite. Heldburgite, Liidecke. — In minute tetragonal crystals, resembling guarinite. Color yellow. H. = 6-5. Composition unknown. In feldspar of the phonolyte ot the Heldburg, near Coburg. Helvite, p. 302. — Occurs at the mica mine near Amelia Court House, Amelia Co., Vir- ginia. In crystals and crystalline masses, of a sulphur-yellow color, imbedded in ortho- clase. Henwoodite, Collins. — In botryoidal globular masses, crystalline. H. = 4^4-5. G. = 2-67. Color turquoise blue. A hydrous phosphate of aluminum and copper (7 p.c. CuO). West Phenix mine, Cornwall. Herrengruxdite, Brezina (= Urvolgyite, SzaboV — In spherical groups of six-sided tabu- lar crystals (monoclinie). Cleavage basal perfect. H. = 2-5. G. = 3-132. Lustre vitreous, pearly on cleavage face. Color emerald to bluish green. A hydrous basic sulphate of copper, allied to langite. From Ilerrengrund (= Urvulgy) in Hungary. DESCRIPTIVE MINERALOGY, 429 Hessite, p. 228. — Pseudo-isometric (triclinic) according to Becke, but the conclusion is not beyond question. Het.,erolite (Hetairite), G. E. Moore.— In botryoidal coatings, with radiated structure. H. =0. Gr. = 4-983. Stated to be a zinc hausinaunite. Occurs with chalcophauite at Sterling Hill, New Jersey. Heubachite, Sandberger. — In thin soot-like incrustations, also dendritic. Color black. A hydrous oxide of cobalt and nickel. Heubachthal, near Wittichen. Baden. Heulandite, p. 347. — Oryzite of Grattarola may be identical with liciil; in i!o. In minute white crystals, resembling rice grains {ppvC,a, rice). Elba. HtBBERTiTE, Heddle. — A lemon-yellow powder in kammererite ; in composition probably a mixture of magnesium hydrate and calcium carbonate. From the ehromite quarry in the island of Unst, Scotland. HiERATiTE, Cossa (Traus. Acad. Line, III., vi., 14). — A potassium fluo-silicate, 2KP -f SiFj, obtained in octahedral crystals from an aqueous solution of part of stalactitic concre- tions found at the f umaroles of the crater of Vulcano. The concretions have a grayish color, a spongy texture, rarely compact, and consist of hieratite, lamellas of boracic acid, with selensulphur, arsenic sulpliide, etc. HoMiLTTE, Paijkull. — Near gadolinite and datolite in angles and habit. H. =4'5-5. G. = 3"34. Lustre resinous to vitreous. Color black or blackish brown. Translucent in thin splinters. Composition FeCaBsSiaOio, or analogous to datolite. From the Stocko, near Brevig, Norway. HoPEiTE. — Composition probably ZusPnOs 4- 4 aq. Orthorhombic. Altenberg. HiJBNERiTE, p. 383. — Found (Jenney) near Deadwood, Black HUls, Dakota. Alsoinrho- dochrosite at Adervielle, in the Ilautes Pyrenees. HuNTiLiTE, Wurtz. — An impure massive mineral from Silver Islet, Lake Superior, re- garded as a basic silver arsenide. Hyalotekite, Nordenskiold. — Coarsely crystalline, massive. H. = 5-5'5. G. = 3"81. Lustre vitreous to greasy. Color white to pearly gray. Analysis (incomplete) : SiOn 39 62, PbO 25-30, BaO 20-CG, CaO 700, ign. 0*82, AlaOaK.O, etc., tr. From Langban, Sweden. HYDROfERU.ssiTE, Nordcnskiold. — A hydrous lead carbonate, occurring in white or color- less crystalline plates on native lead at Langban, Sweden. Htdrofranklinite, Ecepper. — A hydrous oxide of zinc, manganese and iron, occurring in brilliant regular octaliedrons, with perfect octahedral cleavage. Sterling HUl, N. J. Never completely described. Htdrophilite, Adam. — Calcium chloride ; see chlorocalcite, p. 260. Hydrorhodonite, Engstrom. — A hydrous silicate of manganese (MnSiOs + aq). Massive, crystalline. Color red brown. L&ngban, Sweden. Ilesite, Wuensch. — In loosely adherent ciystalline aggregates. Color white. Taste bitter, astringent. Composition (M. W. lies) RSO4 +4 aq, with R = Mn : Zn : Fe=: 5 : 1 : 1. Occurs in a siliceous gangue in Hall Valley, Park Co., Colorado. Iodobromite, v. Lasaulx. — Isometric, octahedral. G. = 5 713. Color sulphur yellow, sometimes greenish. Composition 2Ag(Cl,Br) + Agl. From the mine "Schone Aus- sicht," Dernbach, Nassau. Iron, p 226. — The later investigations of the so-called meteoric iron of Ovlfak, Disco 430 DESCRIPTIVE MINERALOGY. Bay, Greenland, more especially by Tomebohm and J. Lawrence Smith, leave no doubt that it is in lact terrestrial. Jamesonite, p. 251. — Occurs in Sevier Co., Arkansas, with other ores of antimony. Jakosite. — Occurs in tabular rhombohedral crystals at the Vulture mine, Arizona (Silliraan), and at the Arrow mine, Chaifee Co., Colorado (Konig). Composition K2S0i + FeaSsO.o + 2PeoHoOo. Kentrolite, Damour and vera Rath. — In minute orthorhombic crystals, jjrouped in sbeaf-like forms like stilbite. H. = 5. G. =0-19. Color dark reddish brown. Composition probably PbaMunSioOa. From Southern Chili. Krennerite, vom Rath {Bunsenin, Krenner). — Orthorhombic ; in vertically striated prismatic crystals. Color silver white to brass yellow. Lustre metallic, brilliant. A tellu- ride of gold, perhaps related to calaverite. Nagyag, Transylvania. Lautite, Frenzel — Generally massive. H. =3-3-5. G=4-96. Metallic. Color iron black. Formula given CuAsS, but very probably a mixture. Lauta, Marienberg, Saxony. Lawrencite, Daubree. — Iron protochloride occurring in the Greenland native iron, etc. Leadhillite, p. 390. — Susannite is veiy probably identical with leadhillite. Leidyite, Konig. — In verruciform incrustations, consisting of fine scales. Color various shades of green. A hydrous silicate of aluminum, iron, magnesium, and calcium. Leiper- ville, Delaware Co., Penn. Leucite, p. 318. — Has been made artificially by Fouque and Levy ; also an iron leucite has been made by Hautefeuille ; optical character as of natural crystals. LEUCOCriALCiTE, Sandbergcr. — In slender, nearly white crystals. According to an imper- fect description, an arsenical tagilite. Wilhelmine mine in the Spessart. Leucophanite, p. 300. — Monoclinic (Bertrand, Groth), twins analogous to those of har- motome. Leucotile, Hare. — In irregularly grouped silky fibres of a green color. Analysis : SiOj 28-98, AI2O3 6-99, Fe^Os 8-16, MgO 29-78, CaO 7-37, Na^O 1-32, K^O tr., H^O 1729 = 99-89. Reichenstein, Silesia. LiBETHENiTE, p. 373. — Pscudo-orthorhombic, monoclinic, according to Schrauf. LiSKEARDiTE, Maskelyuc. — Massive, incrusting. Color white. Stated to have the compo- sition AlcAsjO, ,,1611.20. Not fuUy described. Liskeard, Cornwall. LiviNGSTONiTE, p. 232.— Composition probably HgaS + 4Sb2S3. LouisiTE, Honeymann. — A transparent, glassv, leek-green mineral. H. = 6-5. G. = 2-41. Analysis (H. Louis): SiO, 6374, Al.O^ 57, FeO 125, MnO tr., CaO 17-27, MgO 0-38, KoO 3-38, Na,O008, H.,0 12 96 = 99-63. Macfarlanite, Sibley. — A name given to the complex granular silver ore of Silver Islet, Lake Superior, which lias yielded the supposed huntilite. Magnolite, F. A. Genth. — In radiating tufts of minute acicular crystals. Color white. Lustre silky. Composition perhaps TTg.,Te04. A decomposition product of coloradoite, Keystone mine, Magnolia District, Colorado. DESCKIPTIYE MINEKALOGr. 431 Mallardite, Camot. — In colorless cystalline fibrous masses. Composition MnSOi + 7aq. From the ''Lucky Boy" silver mine, Butterfield Canon, near Salt Lake, Utah. Maxgaxosite, Blomstrand. — Isometric. Cleavage cubic. H. = 5-6. tJ. = 5'118. Lustre vitreous Color emerald green on fresh fracture, becoming black on exposure. Composition ]VInO. From Langban, and from the Mossgrufva, Xordmark, Sweden. Marmairolite. Hoist. — In fine crystalline needles. H. = 5. G. = 3 07. Color pale yellow. Composition near enstatitej but with 6 p.c.NajO and 1-9 p.e. K..,0. Langban, Sweden. Matricite, Hoist. — In crystalline masses. H. = 3-4. G. =2*53. Color gray. Feel greasy. A hydrous silicate of magnesium, near villarsite, but with one molecule H2O. From the Kraugriiiva, Wermland, Sweden. Melaxotekite, Lindstrora. — Massive, cleavable. H. = 6 3. G. = 5 73. Lusti-e metallic to resinous. Color black to blackish gray. Composition PboFe-SijOa (analogous to ken- trolite). With magnetite and yellow garnet at LSngban, Sweden. Melaxothallite, Scacchi. — Copper chloride from Vesuvius. Melaxterite, p. 395. — Lriclife of Camot is a variety containing 19 p.e. MnO. " Lucky Boy " silver mine, Butterfield Canon, near Salt Lake, Utah. MELIPHA^^TE, p. 300. — Tetragonal according to Bertrand. ISfEXACCAXTTE, p. 269. — HydroUvienite cti Blomstrand is a partially altered variety, con- taining a little water. From Smaland, Sweden. Mica Group, pp. 311 to 315. — Tschermak has shown that all the species of the mica group are monocUnic. an axis of elasticity being inclined a few degrees to the plane of cleavage ; these conclusions are confirmed by Bauer ; and von Kokscharof shows that in angle there is no sensible deviation from the orthorhombic type. Tschermak divides the species into two groups as follows : I. II. Biotites: Anomite. Meroxene, Lepidomelane. Phlogopiles : Phlogopite, Zinnwaldite. ( Lepidolite, Muscovites : < Muscovite, ( Paragonite. Margarites : Margarite. In group I. are included all the micas in which the optic axial plane is perpendicular to the plane of symmetry ; and group II. includes those in which it is parallel to the plane of symmetry. Thus, the former species biotite is divided on this principle into anomiie {cxvoftoi, contrary to law) and n\eroxene (Breithaupt's name for the Vesuvian biotite). For example, the mica occurring with diopside in granular ealcite at Lake Baikal is anomite, as also that from Greenwood Furnace, N. Y. Meroxene is represented by the Vesuvian magnesian mica. Muscovite includes also some of the "hydro-micas" to all of which belong the formula (II.K)..,Al,.Si..O. : plienuite is a name given to some muscovitcs approach- ing lepidolite in composition, and thus not conforming to the imisilicate type. For the full discussion of the subject, see the original memoirs of Tschermak and also those of Rammels- berg, etc., referred to in Appendix III. llanrldonit'' (Ileddlel, from Scotch granite, etc., is a varietv of biotite, characterized by containing much PeO (to 19 p.e ) and little MgO. SiderophyUite (H. C. Lewis) from Col- orado contains all FeO (25-5 p c.) and only a trace of magnesia. MicROLiTE, p. 359 —In small brilliant octahedrons, light gravish vellow to blackish broMm (Nordenskiold), at Uto, Sweden. G. = 5'25. Composition Ca.Tao'OT, with also MnO and MgO. 432 DESCRIPTIVE MINERALOGY. Occurs at the mica mines of Amelia Co., Virginia (Dunnington). In modified octa- hedrons, also in large (to 4 lbs.) imperfect crystals. G. = 5G56. Composition essentially CagTaoU:, with also !, CbOFa. Also occurs at Branchville, Conn. (Brush and Danaj. Maddainite of Shepard. from lladdam, Conn., is related, perhaps identical. MiLARiTE. — Orthorhombic, pseudo-hexagonal. Composition HKCaoAl-jSiioOjo. Origin- ally described from Val Milar, but really (Kuschel) from Val Giuf, Switzerland (giuiite). MiMETiTE, p. 366. — According to Bertrand and Jannettaz, crystals of pure lead arsenate are biaxial ; as the amount of lead phosphate increases the angle diminishes and pure lead phosphate (jjyromorphite) is uniaxial ; but this may be due to the grouping of uniaxial crystals in positions not quite parallel. Occurs with vauadinite in Yuma Co., Arizona (Silliman, Blake). MixiTE, Schrauf. — Incrusting, crypto crystalline. Color emerald to bluish green. H. = 3-4. Gr. =2"66. A hydrous arsenate of copper and bismuth. Joachimsthal. MoLYBDEXiTE, p. 233. — Perhaps orthorhombic (Groth). MoLYBDOMEXiTE, CoBALTOMEXiTE, Bertrand (Bull. Soc. ^[in., v. 90). — Minerals belonging to the same group of selenites as chaleomenite. Molybdomenite is a lead selenite, occur- ring in thin white lamellae, nearly transparent, orthorhombic, two cleavages. CobaUome- nite is a cobalt selenite in minute rose-red crystals occurring in the midst of the selenides of lead and cobalt. From Caeheuta, Argentine Republic. MoNAZiTE, p. 368. — From Arendal, a normal phosphate (Rammelsberg) of cerium, lan- thanum and didymium, containing no thorium nor zirconium. Penfiekl has proved that the tliorium sometimes found is due to admixed thorite. Turneriie, according to Pisani, has the same composition. Occurs in very brilliant highly modified crystals at Milholland's MiU, Alexander Co., N. C. ; also at other localities in North Carolina (Hidden). In large masses with microlite at the mica mines of Amelia Co., Va. ; also at Portland (near Middletown; Conn. MoNETiTE, C. U. Shepard and C. U. Shepard, Jr. — In irregular aggregates of small tri- clinic crystals. H. = 3-5. G. =2'75. Lustre vitreous. Color pale vellowish white. Semi- transpareut. Composition HCaPO^, requiring PoO, 52-20, CaO 41 18. H,,0 6-62 = 100. Occurs with gypsum and monite at the guano islands, Moneta and Mona, in the West Indies. jNIoxite occurs as a slightly coherent, uncrystalline, snow-white mineral. G. = 2"1. Composition perhaps CajPaOo + H-^O. MoRDEXiTE. — Steeleite of How is an altered mordenite from Cape Split, N. S. ^lor- denite (How) has the composition SiOj 6840, Al.Og 12-77, CaO 346, Ka^O 2-35, H.,0 13-02 = 100. Nagtagite, p. 249. — Perhaps orthorhombic (Schrauf). Natrolite, p. 342. — Monoclinic, according to Liidecke. Neoctaxite, Scacchi. — In minute tabular crystals of a blue color. Supposed to be an anhydrous copper silicate. Mt. Vesuvius. Nephrite, p. 297.— The general subject of nephrite and jadeite in their mineralogical and archa?ological relations has been exhaustively discussed by Fischer in a special work on that subject. Newbektite, vom Rath. — In rather large tabular orthorhombic crj-stals, Composition MgaH^PoOs -h 6 aq. From the guano of the Skipton Caves, Victoria. DESCRIPTIVE MINEPwALOGY. 433 ^NlTROBARiTE.— Crystals of native barium nitrate have been obtained from Chili; in apparent octahedrons formed of the two tetrahedrons. NocERiXE, Scucchi. — In white acicular crystals, perhaps rhombohedral ; regarded as a double fluoride of calcium and magnesium. From the volcanic bombs of Nocera. OcTAHEDRiTE (Anatase), p. 377.— Belongs to the monoclinic system, according to Mal- lard's view (see p. 186). Found in nearly colorless transparent crystals at Brindletown, Burke Co., N. C. (Hidden). Onofritk.— A massive mineral (G. = 7 63), from Marysvale, Utah, has the composition Hg(S,Se), with S : Se = 6 : 1. It thus corresponds nearly with Haidinger's onofrite, which has S : Se ::= 4 : 1. Orpiment (p. ','31) and realgar (p. 231) occur in Iron Co., Utah (Blake). Orthoclase, p. 325. — Klockmann (Z. Krysi, vi., 493) has described twins of orthoclase from the Scholzenberg, near Warmbrunn, in Silesia, the twinning planes in different cases were i-i, 0, 2-i, 2~i, /, i-3. Orthite, p. 308. — Found in imperfect bladed crystals at the mica mines in Amelia Co., Virginia, with monazite, columbite, etc Ottrelite, p. 358. — A variety of ottrelite from Venasque, in the Pyrenees, has been called venasquiie (Damour). OxAMMiTE. — Ammonium oxalate (Shepard) from the Guanape Islands. Also called guana- pite by Raimondi. Ozocerite. — A related mineral was has been found in large quantities in Utah. Pachnolite, p. 265. — See thomsenoUte, p. 438. Peckhamite, J. L. Smith.— From the Estherville, Emmet Co., Iowa, meteorite. In. rounded nodules, with greasy lustre, and light greenish-yellow color. G. = 3'23. Compo- sition equivalent to two molecules of enstatite and one of chrysolite. Pectolite, p. 327. — Walkerite (Heddle) is a closely related mineral from the Corstor- phine Hill, near Edinburgh, Scotland. Pelagite, Church.— a nam6 given to the composite manganese nodules obtained by the '* Challenger" from the bottom of the Pacific. Penwithite, Collins.— Described as a hydrated silicate of manganese (MnSiOs -t-2aq) from Penwith, (.'ornwall. Peropskite, p. 270. — Recent observations refer it to the orthorhombic system, the crys- tals being complex twins. Ben-Saude, however, regards it as isometric and parallel hemihedral, the observed double refraction being due to secondary causes, see p. 190. Petalite, p. 295. — Hydroeastorite is an alteration product of castorite from Elba (Grat- tarola). Phaemacosideritb, p. 376. —Pseudo-isometric, according to Bertrand, see p. 186. Phenacite, p. 301.— Obtained well crystallized from Switzerland, perhaps from Val Giuf. Also (Cross and Hillebrand) from near Pike's Peak, El Paso Co., Colorado. PHILLIPSITE, p. 345.— Crystalline system monoclinic (Streng), with a higher degreo of pseudo-symmetry due to twinning. 28 434 DESCKIPTIVE MINERALOGY. Phosphurantlite, Genth. — As a pulverulent incrustation, of deep lemon-yellow color. Composition probably (U0o)3P.;0„ + 6 aq Occurs witli other uranium minerals at the Flat Kocii mine, Mitchell Co., N. C. PiciTE, Nies. — An amorphous, dark biown hydrous iron phosphate from the Eleonore mine and the Rothlilufchen mine, near Giessen". Of doubtful homogeneity. PiCKERiNGTTE, p. 395. — SoHomaife (Goldsmith), from the Geysers, California, andpicroal- lumogene (lioster), from Elba, are closely related minerals. PiLOLiTE, Heddl*!. — A name sugsjcsted for some minerals from Scottish localities of nearly related composition, which have gone by the names "mountain leather" and '-mountain cork." Plagiocitrite, Sandberger, Singer. — A hydrous sulphate of alumina, iron, potassium, sodium, etc., occurring in lemon-yellow microii^copic crystals, and formed from the decom- position of pyrite at the Bauersberg, near Bischofsheim vor der Rhon. Platinum, p. 223. — A nugget weighing 104 grams, and consisting of 46 p.c. platinum and 54 p.c. chromite, was found near Pittsburgh, N. Y. (Collier). Plumbomanganite, Hannay. — Described as a sulphide of manganese and lead, but doubt- less a mixture. Source unknown. Plujtbostanxite, Raimondi. — An impure massive mineral, described as a sulph-antirao- nite of tin, lead and iron, but of doubtful homogeneity. From the district of Moho, Peru. PoLYDYMiTE, Laspcyrcs. — Isometrlc, octahedral. H. = 4-5. G. = 4-808-4-816. Com- position Ni4S5. From Griinau, Westphalia. Laspeyi-es regards the saynite of von Kobell, griinauite of Nicol, as an impure polydymite. PoLYHALiTE, p. 393. — Krugite (Precht) is a related mineral from Xew Stassfurt. Com- position, if homogeneous, K.JSO4 + MgSOi -I- 4CaS04 H- 2 aq. Priceite, p. 382. — Pandermite (vom Rath) is a borate from Pandermaon the Black Sea, near priceite, if not identical with it. PsEUDOBRooKiTE, Koch. — In thin tabular striated crystals, orthorhombie. H. = 6. G. = 498. Lustre adamantine, on crystalline faces. Color dark brown to black. Con- tains principally the oxides of iron and titanium. From the andesite of the Aranyer Berg, Transylvania, and Riveau Grand, Monte Dore, also with the asparagus stone of Jumilla, Spain (Lewis). Near brookite. Pseudonatrolite, Grattarola. — In minute acicular crystals. Colorless. A hydrous silicate (02-6 p.c. SiOj) of aluminum and calcium. From San Piero, Elba. Psilomelane, p. 282. — Calvonigrita (Laspeyres) from Kalteborn is a variety. Pyrite, p. 243. — Occurs in highly modified crystals in Gilpin Co., Colorado. Pybolusite, p. 278. — According to Groth, the prismatic angle is 99° 30'. Pyrophosphorite. C. U. Shepard. Jr. — A massive, earthy, snow-white mineral from the West Indies. Described as a pyrophosphate of calcium and magnesium. Pyrrhotite, p. 241. — Perhaps only pseudo-hexagonal, the apparent form due to twin- ning. Quartz, p. 284. — The smoky quartz of Branchville, Conn. , contains very large quanti- ties of liquid COa (Hawes), also N,H,S,S02,H3-N,P (A. W. Wright). DESCRIPTITE MINERALOGY. 435 Ralstokite, p. 265.— Composition (Brandl) 3iNa.;,Mg,Ca)Fg + 8A1..F„+ 6H0O. Raxdite, Konig. — A canary yellow incnistatiou on granite at Frankford, near Phila- (leiijhia. Contains calcium and uranium, but composition doubtful. Reddingite, G. J. Brush and E. S. Dana.— Orthorhombic ; habit octahedral ; form near that of scorodite. H. =8-3;j. G. =8-l0. Lustre vitreous to sub-resinous. Color pale rose pink to yelldwish white. Composition MuaP.jO,. + 3 aq, with a varying amount of iron (5-8 p.c.FeO). With other manganesian phosphates at Branch vilie, Conn. REmiTE, K. V. Fritsch, Liidecke. — A tetragonal iron tungstate (FeAV04) near seheolite in form, and perhaps a pseudomorph. From Kimbosan, Japan. Resin. — The following are names I'ccently given to various hydrocarbon compounds : ajkite, bernardinite, celestialite, duxite, gedanite, hofmannite, huminite, ionite, kullachite, muckite, neudorlite, phytocollite, posepnyte. Rhabdophaxe, Lettsom. — A cerium phosphate, perhaps the same as phosphocerite. Rhodochrosite, p. 403. — A Hungarian variety, containing S9 p.c. FeCOg, has been called manganosiderite (Bayer). Occurs at Branchville, Conn,, containing 16'76 p.c. FeO (Penficld). Rhodizite. — According to Damour, rhodizite of Rose, from the Ural, is an alkaline boro- aluminate. Pseudo-isometric according to Bertrand. RoGERSiTE, J. L. Smith. — A thin mammillary crust, of a white color, on samarskite. A hydrous eolumbate of yttrium, etc., exact composition undetermined. Mitchell Co., X. C. RoscoELiTE, p. 367. — A silicate, according to recent analyses by Genth, having the for- mula K(Mg,Fej(Aln,Vo)oSi,„03n + 4 aq ; also (Hanks) from Big Red Ravine, near Sutter's Mill, Cal. RosELiTE, p. 372. — True composition RsAsjOa + 2 aq (Winkler), hence analogous to fair-, fieldite, p. 426. RuBiSLiTE, Heddle. — An uncertain chloritic substance from the granite of Riibislaw, near Aberdeen, Scotland. RuTiLE, p. 276. — Pseudo-tetragonal according to the view of Mallard (see p. 186). Occurs in splendent ci-ystals in Alexander Co., N. C (Hidden). Samarsktte, p. 361. — The North Carolina mineral has been shown to contain erbium, ter- bium, phillipium, decipium (Delafontaine. Mai'ignac). A siipposed new element, mosan- drum. was also announced by Smith. Vietlnghvfite is a ferruginous variety from Lake Baikal, in the Ural. Sarawakite. Frenzel. — Occurs in minute crystals in the native antimony of Borneo; perhaps scnarraontitc. ScAPOUTE, p. 817. — The scapolites have been shown by Adams to contain chlorine (up to 248 p. c.) when quite unaltered. The analyses of Neminar, Sipocz, and Becke prove the same. OntariolUe (Shepard) is a variety occurring in limestone at Galway, Ontario, Canada. SoHNEEBERGlTE. Brezina.— -In isometric octahedrons of a honey-yellow color from Schnee- berg, Tyrol. Contains lime and antimony, but exact composition unknown. ScHoRLOMTTE. p. 337. — Thesocalled schorlomite of the Kaiserstuhl is, according to Knop, either a titaniferous melanite or pyroxene. 436 DESCKIPTITE MINEKALOGY. Semseyite, Krenner. — Stated to be related to plagionite ; from Felsobanya. Not yet described. Senarmontite, p. 384. —Pseudo-isometric according to Mallard (p. 186). Grosse-Bohle, who has investigated the subject, suggests the same for arsenolite. Sepiolite, p. 349. — Chester has analyzed a fibrous variety from Utah. Serpentine, p. 3.50. — Schrauf (Z. Kryst., vi.. 321) has studied the magnesia silicates from the serpentine region near Budweis, Southern Bohemia. He introduces the following new names : Kelyphite, a serpentinous coating of altered crystals of pyrope ; J:Jiiophife. a chloritic variety of serpentine ; LeritiUte (wrong orthography for lennilite) in composition near the vermiculite of Lenni (Cooke), hence name ; tSiHciojjhite, a heterogeneous substance high in silica ; Hydrohiotite (same name used by Lewis) a hydrated biotite ; Berlanite, a chloritic substance filling cavities oetween the granite and serpentine ; Schuchardtile, the so-called chrysopraserde from Gliisendorf, Silesia. He also uses the general name parachlorite for substances conforming to mAlsSisOia + ??R2Si04 + /Jaq, and protochlorite for those corre- sponding ton^Al.SiOs + ^(RjSiOi) 4- piq. Totaigite (Heddle) is an uncertain serpentinous mineral, derived from the decomposition of malacolite. From Totaig, Rosshire, Scotland. Serpierite, Des Cloizeaux. — In minute tabular crystals ; orthorhombic. Color greenish. Stated to be a basic sulphate of copper (Damour). Prom Laurium, Greece. Stderazot, Silvestri— Iron nitride, a coating on lava at Etna. Sideronatrite, Raimondi. — Sidpronatrite, from Huantajaya, Peru, and urusite (Frenzel) from the island Tschleken, Caspian Sea, arc hydrous sulphates of iron and sodium, near each other and related to the doubtful bartholomite. Sipylite, Mallet. — Tetragonal, in octahedrons. Form near that of fergusonite. Cleav- age octahedral ; usually massive, crystalline. H — G. G. = 4-89. Color brownish black to brownish orange. Essentially a eolumbate of erbium, cerium, lanthanum, didymiura, uranium, etc. With allanite on the Little Friar Mt., Amherst Co., Va. Smaltite, p. 245. — Occurs near Gothic, Gunnison County, Colorado. Sph^rocobaltite, Weisbach.— In small spherical masses, concentric, radiated. Color within rose-red. H. =4. G. = 4'02-4 13. Composition C0CO3. With roselite at Schneeberg, Saxony. Spodiosite, Tiberg. — In flattened prismatic crystals. A calcium j^hosphate, and per- haps pscudomoz'phous. From the Krangrufra, Wermland, Sweden. Sphalerite, p. 237. — The sphalerite from the Pierrefittc mine, Vallee Argeles, Pyrenees, contains gallium (L. de Boisbaudran), and various American (Cornwall) and Norwegian (Wleugel) varieties afEord indium. Spodumene, p. 29.5. — The true composition is expressed by the formula LioAl.jSijOia, as proved by numerous recent analyses. Occurs in small prismatic crystals of a deep emerald green to yellowish green color, with beryl (emerald), I'utile. monazite, etc., in Alexander Co., N. C. This variety, which has been extensively introduced as a gem, was called hiddenite by J. L. Smith, after W. E. Hidden. The alteration products of the spodumene of Chesterfield and Goshen, Mass., have been described by A. A. Julien. Occurs iii immense crystals at Branchville, Conn. (Brush and Dana). The unaltered min- eral is of an amethystine pui*ple color and perfectly transparent, but the crystals are mostly altered. This alteration lias yielded (1) a substance called y^-spodumene, apparently homo- geneous, but in fact an intimate mixture of albite and eucryptite (q. v. , p. 42'!) ; also cvmatolite, a mixture of albite and muscovite ; also albite alone; muscovite ; microcline, and killinite. DESCRIPTIVE MINERALOGY. 437 Staurolite, p. ZZQ.—XanthoUte (Ilecldle) from near Milltown, Loch Ness, Scotland, is a closely related mineral. Sternbergite, p. 240. — Argentopyrite, Argyropyrite and Frieseiie are varieties, or at least closely related minerals. They are essentially identical in form, while Strong shows that the composition of the series may be expressed by the general formula AgaS -t- Stibianite, Goldsmith. — A doubtful decomposition product of stibnite, near stibiconite. From Victoria. Stibiconite. — Extensive deposits of an antimony oxide, near stibiconite, occur at Sonora, Mexico. The ore carries silver chloride. Stibnite, p. 232. — Occurs with other antimony minerals in Sevier Co., Arkansas. In groups of large splendent crystals on an island in western Japan. Stilbite, p. 346. — Monoclinic, and isomorphous with harmotome and phillipsite (v. Lasaulx). Strengite, Nies. — Orthorhombic, and isomorphous with scorodite. Generally in spherical and botryoidal aggregates. H. = 3-4. G. = 2-87. Lu.stre vitreous. Color various shades of red to colorless. Composition Fe.P.OH -i- 4 aq. From the Elconore mine near Geissen, the Rothiilufchen mine near Waldgirmes ; also in cavities in the dufrenite from Rockbridge Co. , Va. (Konig). Strontianite, p. 406. — Occurs at Hamm, WestphaUa, sometimes in highly modified pseudo-hexagonal crystals, resembling common forms of aragonite (Laspeyres). StIjtzite, Schrauf. — A silver telluride, occurring in pseudo-hexagonal crystals of a lead gray color. Named from a single specimen probably from Nap-yag. Szaboite, Koch. — In minute triclinic crystals, near rhodonite in form. H. = 6-7. G. = 3*505. Lustre vitreous ; sometimes tending to metallic and pearly. Color hair brown ; in very thin translucent crystals brownish red. A silicate of calcium and iron (KSiOs) re- lated to babiiigtonite. Occurs with pseudobrookite in the andesite of the Aranyer Berg, Transylvania; Mt. Calvario, Etna ; Riveau Grand, Monte Dore. SzMiKiTE, v. Schrockinger. — Amorphous, stalactitic. Color whitish to reddish. Com- position MnSOj + H.jO. Felsobanya, Transylvania. TaIiKTRIplite (Igelstrom). — A phosphate of iron, manganese, magnesium and calcium ; probably a triplite remarkable as containing MgO (17"43 p.c.) and CaO (14'91). From Horrsjoberg in Wermland, Sweden. Tantalite, p. ."59. — Occurs in North Carolina; in Coosa Co., Ala. Mangantantalite (Nordenskiold) is a manganesian variety (9 p.c. MnO) from Uto, Sweden. Tarapacaite, Raimondi. — A supposed potassium chromate, occurring in bright yellow fragments in the midst of the soda nitre from Tarajmca, Peru. Taznite, Domeyko. — Regarded as an arsenio-antimonate of bismuth, but probably a heterogeneous substance. Tellurite. — The tellurium oxide (TeOj) occurs in minute prismatic, yellow to white crj'stals, iinbeildcd in native tellurium ; also incrusting. Keystone, Snmggler and John Jay mines in Colorado. Tellurium, p. 227. — An impure A'ariety from the Mountain Lion mine, Colorado, has been called lignite. 438 DESCEIPTIVE MINERALOGY. Tenxantite, p. 256. — Fredricite (H. Sjogren) is .a variety from Palu, Sweden, con- taining lead (U p.c.), tin (1-4 p.e.) and silver (2*9 p.c.). Tenorite, p.. 267. — Made triclinic, on optical grounds, by Kalkowsky. Tequesquite. — A corruption of tequixtjuitl, a name used in Mexico to designate a mix- ture of different salts. Tetrahedrite, p. 255. — Occurs near Central City, Gilpin Co., Colorado, in crystals coating clialcopyrite in parallel position. Also at Newburyport, Mass. ; in Arizona (16*23 p.c. Pb). Frigidite (D'Achiardi) is a variety with 12-7 p.c. Fe, etc., from the Valle del Prigido, Apuan Alps. Thaumasite, Nordenskiold. — Massive, compact. H. = 3*5. G. =1-877. Color white. Lustre greasy, dull. Composition deduced CaSiOa + CaCOs + CaSOj + 14 aq, but it is very doubtful whether the material analyzed was homogeneous. Thenardite, p. 390. — Occurs in large deposits on the Rio Verde, Arizona (Silliman). Thomsenolite, p. 265. — According to Klein and, later, Brandl and Groth, thomsenolite and pachnolite are distinct minerals. ThomsenoUte is monoclinic, /i = 89° Z'i^', and c (vert.) -.h-.a — 1-0877 : 1 : 09959, and has the composition (Na + Ca)P3 + AloPeV H.2O. Pachnolite is monoclinic,/^ = 89" 40', c (vert.) : & : a = 1-5320: 1 : 1 626, and has the compo- sition (Na 4- Ca)P3 + AloPe. Pachnolite is a cryolite with two sodium atoms replaced by one calcium atom, and thomsenolite is the same, with also one molecule of water. Thomsonite, p. 342. — Occurs in amygdules in the diabase of Grand Marais, Lake Supe- rior ; also in polished pebbles on the lake shore. The j^ebbles are sometimes opaque white, like porcelain ; sometimes green in color and granular (variety caDed lintonite) ; some- times with fibrous radiated structui'e, of vg-rious colors, and of great beauty. The last are valued as ornaments. Thinolite. — Calcium carbonate, forming large tufa-like deposits in Nevada, a shore formation of the former Lake Lahontan. Regarded by King as pseudomorph after gay- lussite, but this is doubtful. Thorite, p. 840. — A variety of thorite is called uranothorite by Collier ; it contains 9-96 UoOs. Massive. G. = 4-126. Color dark red-brown. From the Champlain iron region, N. Y. Titaxite, p. 335.— Occurs, often in enormous crystals or groups of crystals, at Renfrew, Canada, with zircon (twins), apatite and amphibole. AUhedite (Blomstrand) is a variety from Smaland, Sweden, containing 2-8 p.c. YO. Titanomorphite is a name given by v. Lasaulx to a part of the white granular aggregates surrounding rutile and menaccanit'.'/and derived from their alteration. It is a calcium tita- nate, according to Bettendorff's analysis, but Cathrein (Z. Kryst.. vi., 244) shows that it is really a variety of titanite. Leucosene is a name earlier (1374) given by Glimbel for a similar substance of doubtful chemical natui-c often observed in rocks ; according to Cathrein it is a titanite with or without a mixture of rutile mierolites. Topaz, p. 332. — Pseudo-orthorhombic (monoclinic), according to the view of Mallard (see p. 186). Occurs near Pike's Peak, El Paso Co. , Colorado, and at Stoneham, Maine. Torbanite, p. 418.— WoUon/fonfjife (p. 416) is referred to torbanite by Liversidge ; it is from Hartley, New South Wales, not Wollongong, so that the name is inappropriate. Tourmaline, p. 329.— Pseudo-rhombohedral. according to the view of Mallard (see p. 186). Occurs in white, nearly colorless crystals, at De Kalb, St. Lawrence Co. , N. Y. DESCRIPTIVE MINERALOGY. 439 Tridymite, p. 288. — Pseudo-hexagonal (triclinic), according to Schuster and also v. Lasaulx. Asmanite is probably identical with it. Hautefeuille has made it artilicially ; and it has been observed with zinc spinel as a result of the alteration of zinc muffles. Triphylite, p. 369.— The composition (Penfield) is LiFeP04 = LiaPOi + FeaP.O,, with the iron replaced by manganese in part. Lithidphilite (Brush and Dana) is a variety almost free from iron (down to 4 p.c), and corrcsjwiiding to the lorniula LijMnP04 = LisPOj + MnsP-On. Massive, cleavable {0. 1, i-^. Color salmon,— honey yellow, yellowish brown, light clove brown. Occurs with other mangauesian phosphates in pegmatite, at Kranchville, Fairtield Co., Conn. Triploidite (G. J. Brush and E. S. Dana). — Monoclinic, near wagnerite in form. Gen- erally in fibrous crystalline aggregates II. =40-5. G. = 3 G97. Lustre vitreous to greasy adamantine. Color yellowish to reddish brown, topaz yellow, hyacinth red. Trans- parent. Composition R:,P208 + K(0H)2, with R = Mn : Fe"=- 3:1; hence analogous to triplite, but with (OH) replacing P. With other manganesian phosphates (eosj^horite, lithiophilitc, etc .) from Branch vilJe, Conn. Trippkeite, Damour and vom Rath. — In small brilliant crystals, tetragonal. Color bluish green. Stated to be a hydrous arsenitc of copper. With olivenite in cuprite from Copiapo, Chili. Tysonite, Allen and Comstock. — Hexagonal. Cleavage basal. H. =4*5-5. G. =6'18. Lustre viti-eous to resinous. Color pale wax yellow. Composition (Ce,La,Di)2F6. From near Pike's Peak, Colorado. The crystals are mostly altered to bastnasite (also called hamartite), which is a fluo- carbonate, near parisite. Uraninite, p 274.— Occurs in brilliant black octahedral crystals at Branchville, Conn. G = 9-25. Analysis: UOa 40-08, UO, 54 51, PbO 4-27, FeO 049, HoO 0-88 = 100-23. Also from Mitchell Co.. N. C. ; mostly altered to gummite. Uranocircite, Weisbach. — Orthorhombic, like autunite. Cleavage basal perfect. G. = 8-53. Color yellow green. Composition BaU..P.20j2 + 8 aq. In quartz veins, Saxon Voightland. Franothallite, Schrauf (Z. Kryst., vi., 410). — A uranium carbonate from Joachims- thal, originally mentioned by Vogl. Occurs in confused aggregates of orthorhombic ciys- tals. Calculated formula UCaOe + SCaCOa + 10 aq. Uranotile. p. 341. — Occurs in Mitchell Co., N. C. Genth writes the formula, Ca3(UO,)r,Sio02: + 18 aq. Vanadinite, p. 3G7.— Occurs in highly modified crystals in the State of Cordoba, Argen- tine Republic. Also in very beautiful ruby-red crystals at the Hamburg and other mines in Yuma Co., Arizona (Silliman; Blake), and in yellow to nearly white crystals at other localities in Arizona. Varisctte.— The so-called peganite from Montgomery Co., Ark., is shown by Chester to be identical with Breithaupt's variscite. Composition AliPaOs H- 4 aq. Venerite, Hunt. — An impure chloritic mineral containing copper ; mined as copper ore at Jones' mine, near Springfield, Berks Co., Penn. Vermictjlite, p. 3.~5. — Profovermicniite (Konig) and phUndelpJiite. (Lewis) are minerals related to the other " vermiculites," the whole group being decomposition products of other micas. Vesbtne, Scacchi.^Forms thin yellow crusts on lava of 1631, Vesuvius ; supposed to contain a new element, vesbium. 440 DESCRIPTIVE MINERALOGY. Vesuvianite, p. 405.— Pseudo-tetragonal, according to the view of Mallard (see p. 186> A variety from Jordan&miihl contains 3 p.e. MnO (manganidocrase). Veszelytte. p. 373.— Composition, according to Schrauf, 2(Zn,Cu)3As208+9(Zn,Cu)H,0, -f 9 aq, with Cu : Zn = 3 : 2, and As : P = 1 : 1. Wad, p. 28S.—Lepidophceite (Weisbach) is a related mineral from Kamsdorf, Thuringia. Composition stated to be CuMueOja + 9 aq. Wagnerite, p. 368. — Kjerulfine has been shown to be identical with wagnerite in form and composition ; often partially altered. ■^^'ALPURGITI;, p. 379. — Triclinic (pseudo-monoclinie), according to Weisbach. Wattevillite, Singer. — In minute acicular snow-white crystals, A hydrous sulphate of calcium, sodium, potassium, etc Formed from the decomposition of pyrite at the Bauersberg, near Bischofsheim vor der Rhon. WuLFENiTE, p. 384. — Occurs in fine crystals in the Eureka district, Nevada ; also in Yuma Co., Arizona, sometimes in simple octahedral crystals (Silliman). Xanthophyllite, p. 358. — "Waluewite (v. Kokscharof) is a well crystallized variety from Achmatovsk, Ural. Xenotime, p. 364. — Occurs compounded with zircon in Burke Co., N. C. (Hidden). YouNGiTE, Hannay. — Described as a sulphide of lead, zinc, iron and manganese, but doubtless a mixture. ZixcALUMijnTE, Bertrand and Damour. — Tn thin hexagonal plates, minute. H. =2 5-3. G. - 2-26. Composition 2ZnS04 + 4ZnH,02 + SAliHeOs + 5 aq. From the zinc mines of Lam'ium, Greece. Zircon, p. 304. — Occurs in fine twin crystals (1-/, like rutile and eassiterite) with titanite and apatite, in Renfrew Co. , Canada (Hidden). Also with astrophyllite and arfvedsonite in El Paso Co. , Colorado. Pseudo-tetragonal, according to the view of Mallard (see p. 186). Beccarite (Grattarola) is a variety from Ceylon. APPENDIX A. SYNOPSIS OF MILLER'S SYSTExM OF CEYSTALLOGRAPHY. The followinf^ pages contain a concise presentation of the System of Crystallography pro- posed by Prof. W. H. Miller in 1839, and now employed by a large proportion of the workers in Mineralogy. The attempt has been made to present the subject briefly, and yet with suffi- cient fulness to enable any one having some previous knowledge of Crystallography not only to understand the System, but also to use it himself. For the full development of the subject, especially of its theor&tical side, reference must be made to the works of jVIiller, Grailich, Ton Lang. Schrauf and Bauerman (see the Introduction), as also to the admirable Lectures of Prof. Maskelvne. printed in the Chemical News for 1873 (vol. xxxi., 3, 13, 24,63, 101, 111, 121, 153, 200, 232). General Principles. The indices of Miller and their relation to those of Naumartn.— The position of a plane ABC (f. 751) is determined when the distances OA, OB, OC are known, which it cuts ofE in the 751 aeramed axes X, Y, Z from their point of intersection 0. The lengths of these axes for a single plane of a crystal being taken as units, thus OA = a, OB = i^. OC — r, it is found that the lengths of the corresponding lines OH, OK. OL for any other plane, IIKL, of the same crys- 442 APPENDIX. fcal always bear some simple relation, expressed in whole numbers, to these assumed units This relation may be expressed as follows : OH or in the more common form = h ^- 1 a 1 b /t ■ OH " ~~ k' OK 01 = '. I OL = 1 (1) The numbers represented by //, A;, I are called the indices of the plane and determine its position, when the elements of the crystal — the lengths and mutual inclinations of the axes — are known. When the lines are taken in the opposite direction from O, they are called nega- tive ; the corresponding negative character of th^i indices is indicated by tbe minus sign placed ote/' the index, thus, /<, Jx, or I. When the unit, or fundamental form, is appropriately chosen, the numbers representing h, k, I seldom exceed six. The above relation may also be written in the form : OH OK OL Here i\ ??, ??i, which are obviously the reciprocals of the indices h, k, i respectively, are essentially identical with the symbols of Nauinann. For example, if h = 3, k = 2, I = 2, then ?• = J-, n — ^, ?« = ^, and the symbol (^23) of Miller becomes ^a : ^b : i'-; but by Nau- mann's usage this is so transformed that ?■ = 1, and n > 1 (or sometimes ?i = 1, and r > 1), in other words, by multiplying through by 3, in this case, the symbol takes the form a : ?,h : ^e,* or, as abbreviated, J-^ (fPf)- The symbol a : xb : fc properly belongs to the plane MNR (f. 751), which is parallel to, and hence crystallographically identical (p. 11) with the plane HKL. Special values of the indices h, k, I. It is obvious that several distinct cases are possible : (1) The three indices h, k, I are all greater than unity, then including the various pyramidal planes. The number of similar planes corresponding to the general form j hkl (■ depends upon the degree of symmetry of the crystalline system, and upon the special valu(is of k, k, I, e.g.. h = k, etc. These cases are considered later in their proper place. (2) One of the three indices may be equal to zero, indicating then that the plane is parallel to the axis corresponding to this inde.x. Thus the symbol (hkO), = « : ?!Z» : oo c, or na : b : nc (p. 11), belongs to the planes parallel to the vertical axis '■, as shown in f. 752. They are called prismatic planes. The symbol (hOl), = a : od b : me {-p. 11) belongs to the planes par- allel to the axis b, as in f. 753. The symbol {Okl}, — cca : b : vie, belongs to the planes parallel to the axis a, f . 754. 752 ■■■»,..^ ... 1- ■ "T ' c I hkO 755 -::: c ■ ■....>^ 001 (3) Two of the indices may be zero, the symbol {Jikh then becomes (001), -cca aoi : 5. the basal plane, f. 755 ; (010), = ooa : 5 : ooc; and (100), — a: zob: tdc. These are the three diametral or pinacoid planes. The symbol (010) represents Uio cUmpinacoid (*4) of the Monoclinic system, and (following Groth) the hrachypinark>l. a : na : ma [m-n]. 2. [hkk] h^k. a ma : ma [m-m} 3. [lihk] h>k. a n : ma [m]. 4. [Ill] h = k = l = l. a a : a [1]. 5. [MO] ; 1 = 0. a na : coa [i-n]. 6. [110] h~k = l; 1 = :0. a a : cca [*1. 7. [100] h~l,k = l = 0. a : ■jaa : coa [S]. The seven distinct forms corresponding to these symbols are as follows, taken in the samfl order as on ) p. 14-20, where the forms are described : Cube (f. 7iil).— Symbol [lOOj, including the six planes (100), (010), (100), (OiO), (001). (OOI). See also the spherical projection (f. T(56). 765 [100 [111] [110] [100] [111] [100] [110] [111] Octahedron _(f . 7i)2)^ — Symbol [11 1], including the eighb planes taken in order shown tn f. 762, (111), (111), (ill), (111), (111), (111), (111], (Hi). 'In general the indices of any individual plane are written {hkt), wherea.-! the general symbol [hkl] indicates all the planes belonging to the form, varying in number in the different systems; thus, in this system, [100] is the general symbol for the six similar planes of tht cube. U8 APPENDIX. Dodecahedron it. 763).— Symbol [110], including the twelve planes, (110). fllO) (110^ nio), (101), (Oil), (101). (Oil), (loi), (Oii), (loi), (Oli). ' ^ ^' The relations between these three forms are given in full on pp. 15, 16, and need not b€ repeated. It is to be noticed that the distance between two contiguous poles of [lOOj and fllO] is 45° (see f. 766) ; between those of [lOOJ and [HI] it is 54" 44', and between (110) and (111) it is 35" 16'. Moreover, the angle between (111) and (ill) is 70' 32'. and between (11H and (ill), 109° 28'. ^ ' 766 «1o< y --^ "X^^ ~4io K- / • 201 \ Cor • \ ^ Toi * / ^ yiTu /^ • \^ / • • ^\ ^ \ opt oil dJS (X \{ «p tn q;; \| \^ 152 1?» / 1U2 x /■v 1 tt(X 231. / \ An Mk \^ w 1- Vx ..*\ 201 / JiWN. / l7o*C \ / ym iio^ OJ /l^ .--iio [211] [3111 Tetragonal trisoctfihedron (f. 767, 768). — Symbol [hkk], with 7i,>k, comprising twenty-fom similar planes. Trigonal trisoctaJiedron (f. 769). — Symbol \hhk], with h>k^ also embracing twenty -four bke planes. 771 ^^***^ \ P^ \ '"^ / H /• is U [210] [810] [321] TetraJiexaJiedron (f. 770. 771). — Symbol \JiU)\ including twenty-four like planes. As seen on Ihe spherical projection (f. 76G), the planes of the form [AAOJ lie in a zone with the dodeca- hedral planes, between two pinacoid planes. Hexoetaliedron (f. 772), [hkl\ . — This is the most general form ia the system, including the forty-eight planes enumerated on p. 447. Their position (/t = 3, A; = 2, i = 1) is shown on the spherical projection (f. 766). B. Semihedral Forms, There are two kinds of hemihedral forms observed, as shown on p. 20: (1) the heMiholo> fiedral, where half the quadrants have the whole number of planes ; and (2) the holoheinihedrai where all the quadrants have half the full number of planes. The first kind produces inclined hemihcdrons, indicated by the symbol sjikl].- and the second kind produces j^arrtfZ^e^ hemihe- drone, indicated by the symbol izlkkl}. The resulting forma in the several eases are lui f oUowr ' MILLER'S SYSTEM OF CKYSTALLOGRAPHT. 449 Inclined Hemihedrism. — Tetrahedron (±1). Symbol «[111]. The pliia tetrahedron (f. 773) includes the four planes (111), (111), (111), (111). The minus tetrahedon (f. 774) includes the planes (HI), (111), (Hi), (ill). 774 776 777 4111] K\ll\] K[211] «[121] «[321] Hemi-trisoctaTiedrans. — The symbol K[7i,kk] denotes the solid shown in f. 775, knd /.[/i/nAj the solid shown in f . 776. They are the hemihedral forms of the tetragonal and trigonal trisoctahedrons respectively. Hemi-hexoctahedroii. — The same kuid of hemihedrism applied to the hexoctahedron pro- duces the form shown in f. 777, havincr the general .symbol K[hkl\. Inclined hemihedrism as applied to the three other solids of this system produces forms in no way different, in outward appearance, from the holohedral forms. Parallei, Hemihedrism produces distinct, independent, forms only in the case of the tetrahexahedron and the hexoctahedron. The symbol of the former is -[MO], and of th« latter, - [Mi] ; they are shown in f . 778-782. 7r[210] 7r[210] 7[120] 7r[210] [100] 7r[321J Tetartohedral forms of several kinds are possible in this system, but they are of ^mall piactical interest. MatJiematicnl Relations of the Isometric System. (1) The distance of the pole of any plane P{hkl) from the cubic ( or pinacoid) planes is given by the following equations. These are derived from equation (2), p. 443. Here PX(=PA) is the distance between {hkl) and (100) ; PY(=PB) is the distance between (hkl) and (010); aud PZ(=PC) that between {hkl) and (001). The following equations admit of much simplification in special cases, for {hkO), {7ihk), etc. cos- PA = h^ h^ + k-' + I' cos- PB = *» h'^ 4- k'^ + ^■ ' cos' PC h^ + k'^ + P (2) The distance between the poles of any two planes {hkl) and (pqr) is given by the fol- lowing equation, which in special cases may also be more or less simplified : cos PQ = 7ip + kg + Ir y/{Jt?+h?-{-P){p' + q-' + ri)' (3; Calculation of the values of h, k, I, for the several forms. — {a) Tetragonal trisoctahe a/ on (£. 767). B and C are the supplement angles of the edges as lettered in the figure. cos B = 29 A» 4- 2A" cos C = 2hk + k"" 450 APPENDIX. J or the hemihedral form (f . 775), cos B = /t« + 2k'' (b) Trigonal trisoctahedron. — The angles A and C are, as before, the supplemenca of the iiiterfacial angles of the edges lettered as in f. 769. cos A = „:;-- - - . cos B = ,r^ri rs. 2A^ + k^ 2A« + J^ For the hemihedral form (f. 770), cos B = - "^ ■ . Tetrahexahedran (JL. 770), h? ^ 2hk Jii — k^ ^ For the hemihedral form (f. 778), cos A' = r-r — . cos C = /f^ + k-i •''"'' A» + k^' HexoctaTiedron (f. 773). h-' + 2ki ^ h-' + k'^-r- ^ 2hk + P C03 A = ,„ , „ -„ ; cos B = „ , , , , ,/ , cos C = h'^ + k^ + l'' h' + k^ + l^' ^~ h^hk^+P' h^ - 2kl For the hemihedral form K\hkl\ (f . 777), cos B' li^ + k^ + li' ' Fo, :r[AA:Z], cos A = ^^^_^^— ^; cos C = ;,,^^..^^ . For planes lying in the same zone the methods of calculation given on p. 444 and p. 446 are made use of. In many cases, however, the simplest method of solution of a given prob- lem is by means of the spherical triangles on the projection (f. 766). II. Tetragonal System. In the Tetragonal System, since the vertical axis c has a different length from the two equal lateral axes, the index?, referring to it, is never exchangeable for the other indices, Aand^. TJie general form [hkl] consequently embraces all the planes which have as their symbols the different arrangements of ±h, ±k, ±1, in which I always holds the last place. We thus obtain : Ml JiU 7Jcl hkl kKl m m khl hkl m m hkl khl m m m A. Holohedral Forms. According to the values of 7i, k, and I in this general form (A = 0, k =h, etc.), different cases may arise. By this means we obtain a list of all the possible distinct holohedral forma i D tliis system. They are analogous to those of the Isometric System. Miller. Naumann 1. \^m; h>k. a : na : mc [m-n\ 2. \hhl] ; h = k. a : a : mc [ml. •d. [hOl\ ; h or h = 0. a : CO a : mo [m-%\. 4. [hk^] h>kj = 0. a : na : COG \i-n\. 5. fllOl ; h = k^l,l^ 0. a : a : TO11 > \^ y" l''TO (i v^ ^ K/ "^\ /\xy ^ -A ^^y\ \ Tdhi ^ d^^SJ A ch \ htki\ ifooV^ 1 /^ (Oil ^s)iio .% / y^ \ im SJ /X^ihii i^M^ > sT2lO (hklt) iUki) (klhi) (ikJii) (Ihkl (Bli) (hkli) (Jilki) (Jdhi) {Uchi) {Ihki (khh) In this general form IhkH] the following special cases are possible, each one giving riM to an independent form or group of forms, as seen below : 454 APPENDIX. 3. 4. Bravais-Miller. [hkli] {hkpi 2i] ; k = h.:l = 2h [1122] ; h = k = \.'. 1 = 2,1 = 2, [i / i 7 i V. ;i2^ > J / [0110] [1120] [0111] [M/i] {b) Pyramids of the second, or diagonal series. General symbol [/i?i2h2i], including twelve planes, analogous to those of the pyramid unit series. All the pyramids of this series lie in a zone between the diagonal prism, whose general symbol is [1120], and the basal plane [0001]. Twelve-sided pyramids, or Berylloids (f. 797). — General symbol [hkli], including the twenty- four planes enumerated on p, 453. * The ordot of the terms in the symbols below is made to correspond to that of the indioei I,*, I MILLER S SYSTEM OF CRYSTALLOGRAPnT. 45C B. HemilLedral Forms. The most important of the hemihedral forms in this system are as foil >ws : 1. Pyramidal, bemihedrism. — This comes under the head of holohemihedral forms, which are vertically direct (see pp. 34, 35). It is indicated like the corresponding hemihedrism in the tetragonal system n[hkli\. It is common on apatite. 2. RnoMBOHiODKAL hemihedrism. — These included here are hemiholohedral, and vertically alternate. They are indicated in general by K[1ikli]. This class is import- ant, since it embraces the Ruomboiiedkal Division. («) Rhombohedvons. Symbol K[0/i/i4] ; the unit, or fundamental rhombohedron (+i2, f. 798) has the symbol »c[pill], including the six planes: (Olll), (1011), (1101), (1011), (1101), (Olll). The negative rhombohe- dron (-i?, f. 799) includes the planes: (1101), (Olll), (loli), (Olll), (ioii), (liol). (5) ScalenoliCdronH (f. 800). Symbol KVikli]. '6. Gyroidal, or trapezohedral hemihedrism. — The forms here included are holohemihedral, and vertically alternate. They are indicated by k" \JikU] . see p. 39. 4. Tetratohedrism. — This may be (1) rltmnbohedral, indicated by Kir[hkli] ; or (2) tra/pezohedral (gyroidal), as common on quartz, having the gen- eral symbol kk [Iikli\. Mathematical Relations of the Hexagonal System. In the Hexagonal System, as has been explained, the symbol in general has the form [likli]. where the algebraic sum of A, A, and I is zero. This general symbol has four in- dices, refemng respectively to the three equal lateral axes and the vertical axis, as sho'wn in f. 793, thus showing the fundamental hexngoiinl syriimetry of the forms. Since, however, the position of a plane is known by its intersection with three axes alone, two of the three indices A, k, I are all that are needed in calculation, the third, i, being a function, as given above, of h and k. The mathematical relations of the planes in this system are brought out by referring them to three axes, viz., two equal lateral axes H, K, {= a — 1) oblique (120^ and 60 ) to one another, and a third axis (c) of unequal length perpendicular to their plane. This applies also to the calculation by zonal equations. The indices (u, v, w) of the zona in which the planes {hkli), {pqrt) lie, are given by the scheme : h k h k XXX Xi. = kt — qi v = ip — 7it yr = hq — kp. (1) The distances (see f. 793) of the pole of any plane {7ikli) from the poles of the planc« (1010), (0110), (1100), and (0001) are given by the following equations: 6{2h + k) y/^P -f 4c Vi" + *' -+- hk)' c{h + 2k) y/di" + Ac\h' + k- + hk)' ijk - h) V^i'' + U^h' + ki' + hk)' «. PO = CO. (»•) ,0001) = ,^ 3.,^,,4/i.f.^,, . cos PA. = cos {hkli) (lOlO) = cos PB = cos {hkli) (OliO) = cos PM = cos {hkli) (IlOO) = 456 APPENDIX. (2) The distance (PQ) between the poles of any two planes {7ikli) and ( pgrt) is sfiven by th» equation : pog PQ ^ 3if + 2P(hq + pk + 2hp + 2kq) V [Si- + 4:6-(h- + k' + hk)] [df + 4:c\p' + q' + pq)]' (3) For special cases the above formula becomes simplified ; it serves to give the value ol the normal angles for the several forms in the system. They are as follows : (a) Hexagonal Pyramid [07i/«] , f . 796, cos X (termmal) = ;^, ytttt, \ cos Z (basal) = ^r-r, -rrr-,- For the hexagonal pyramids of the second series [0A27t2i] the angles have the same value. {b) Dihexagonal Pyramid [likH], cosX(seef.797) = 5t-±-f!! Jc. h> k. h = k. k = 0. h = 0. I =0, h> k. [kJiO] ; I = 0,h> k. lllO] ; h=k = l, 1=0. [100] ; k=l =0. [010] ; h = 1 -0. [001] ; h = k -0. d :nb : m'c nd:h : mb a lb •.m'c &: ooh ; m'c cod :h : mc d : nb ; aoc nd :b : cob d : b :_ooc d : cob : ooc ccd :b : cob aod : cob : b [m-u] [m-fi [m]. [m-l], [m->q. [i-h]. li-n]. P4 [0]. These symbols belong to the various distinct forms of this system, as follows : Pinacoids. — («) Basal plane. Symbol [001], including the two planes (001) and (001). (5) Macropinacoid. Symbol [100], including the plane [100], and [100] opposite to it. (c) Brachypinacoid. Symbol [010], including the planes [010] and [010]. Prisms.— (a) Unit prism (/). Symbol 110, including four planes, (110), (ilO), (lIO), (110). (b) Macrodiagonal and brachydiagonal prisms, having respectively the symbols [hkO] and [A-AO], if ?i is greater than k. Thus the symbol t-3 corresponds to [210]> and i-2 to [120]. Domes. — (^7) Macrodiagonal, or macro- domes, having the symbol [hOl] ; and (b) brachydiagonal, or brarhydomes, with the symbol [0A7]. In each case the symbol embraces four similar planes. Octahedrons or Pyramids. — The sym- bol [hhl] belongs to the eight planes of the unit pyramids, all lying in the zone be- tween the unit prism [110], and the base [001]. It h = l tlie form is then [111], and the eight pianos are : (111), (111), (ill), (111), (111), (ill), (iii), (lii). Of the general pyramids two cases are possible, either [/iA;/] or [khl], when h>k, these correspond resjiectively to the prisms [M-0] and [khO]. They are the macrodiagonal and brachydiagonal pyra- mids of Naumann ; thus 2-2 (= a: 26 : 2c) is [211], according to Miller, and 2-2 {=2d'.b: 2c) is [121]. * The same lettering is employed here as in the early part of this work ; it differs from that of Miller in that with him a is the macrodiagonal, and b the brachydiagonal Sixis, Follo'ving G-roth, and later writers (Bauerman, etc.), the macropinacoid has the symbol (lO')^, and the brachypinacoid the symbol (010) ; similarly the macrodomes are in general (¥)l). p.ad the brachydomes (Okl). 458 APPENDIX. For the figures of the above-mentioned forms see pp. 42-44. Their relations will be under- stood from an examination of f. 801. showing the projection of the crystals in f . 758, p. 444. It will be seen that all the macrodiagonal planes lie between the zonal circles (diameters) (110) (001), and (100) (001), and the braehydiagonal planes between (110)(001j and (010) (001). Mathematical Relations of the Orthorhomhic System. (1) For the distance between the pole of any plane P (hlcl) and the pinacoid planes we have in general : cos' PA = cos' QiM) (100) = ^'^'^^ cos* PB = cos'' {hkl) (010) = cos^ PC = cos' m (001) = ^,^,^, ^ ^^^ ^-^^, . (2) For the distance (PQ) between the poles of any two planes {hkl) and {pqr) : hph'^c^ + kga'-c"^ + lra''¥ h h-c" + k^a^(r' + ZWft' h^¥c-' + + l-a'^y^ cos PQ = \\h''h''-c^ + ^•'c^'c' + PaW\ [^j^ftv + fa'c" + r'a'^y^ (3) For planes lying in a zone, the general relation (p. 446) is to be employed. For the special cases, practically of most importance, the simplified equations which follow are used, (4) To determine the lengths of the axes, the general equation may be employed : •r- cos PA = -r cos PB = -y cos PC. h Ti I Here PA, PB, PC are the distances from the pole of any plane ijikl) to the pinacoid planes (100), (010), (001) respectively. The brachydiagonal axis", ^, is made the unit. If the angle between any ^ome or prism "and the adjoining pinacoid plane is given, the relations follow immediately : Xk tan PA = tan Qik^) (100) = -r- oh tan PB = tan (OZ;A (010) = ^ ck tan PC = tan Qi^T) (001) = ^ V. MoNocLtNic System. In the Monoclinic System there are three unequal axes, and one of these makes an oblique angle with a second. The axes are lettered as ehowTi in f. 803, c is vertical, b the orthodiagonal axis, and a the clinodiagonal axis oblique to '•, but at right angles to b. The symbol \Ji}d\ embraces only four similar planes in the most general case, for in consequence of the obliquity of one of the axes, the quadrants above in front correspond alone to those below and b-shind, and those above behind correspond to those below in front. This is seen clearly in the projection of f. 803. For ±h, ±k, ±1 the Bymbol [hkl] includes ttoo distinct forms, viz. : (1) {hkt) {hU, {hkl) (M:\ and (2) {hkl) {hkl) (hkl) {hhl, The various forms are as follows : MILLER 8 SYSTEM OF CRYSTALLOGRAPHY. 459 Pinacoids.— Base [001]. Orthopinacoid [100]. Clinopinacoid [010]. Each symbol, of oooxse, comprehending two planes only. 803 80i Crocoite. Prisms.— [a) Unit prism [110], = (i : ft : oo c (/) of Naumann. This symbol embraces foui similar prismatic planes, [b) Orthodiagonal prisms [AArO], where 7i > k. the poles .of these pri-ms fall on the prismatic zonal circle between 100 and 110 (see f. 803). They correspond to the prisms i-n {= d : nb : oor) of Naumann. (c) Clinodiagonal prisms. Symbol [MO], h > k, lying between (110) and fOlO). They correspond to 4-/6 ( = ."4 : ^ : <»c) of Naumann. Domes.— [a) Hemi-orthodomes, including two cases, (101) and (lOJ), the mimts domes of Naumann (opposite the obtuse angle) ; and also (101) aJid (101)), the plus domes of Naumann (opposite the acute angle fi). [b) Clinodomes. Symbol [OA?], embracing four similar planes (OAi) (OAO, (OW), {Okt). The clinodome [Oil], equivalent to 1-i (=:QC>(i : b : vie), is one case in this form. Pyramids.— The pyramids are all hemi-pyramids. {a) The symbol {hU] includes the unit pyramids in a zone between [110] and [001]. {b) The symbol {hkl\ includes two sets of hemi- pyramids, whose indices have been given on p. 416, corresponding respectively to — P and +P of Naumann. If A is greater than k these are orthodiagonnl pyramids, corresponding to ±{A : nb : a^ c) of Naumann. The symbol [khl] on the same supposition includes two sets of planes, like those of p. 4.1 S, and differing only in being clinodiagonal ; equivalent to {nd : ^ : oo c) of Naumann. The orthodiagonal plailes lie between the zone (100), (001) and (110), (001), while the clino- diagonal are between the latter zone and (010) (001), as is seen on f. 803, which {fives the projection for f. 804. Mathematical Relations for the Monodinic System. (1) The distances of the pole of any plane {JikV) from the pinacoid planes are given by the f( Uowing equations : cos PA = COS (hkt) (100) = hbc + lab COS ^ Vk-b-C^ + k^ord^ Bin'^ /3 + l-a^b- + 2hlab-c cos )3 ' kac sin )3 cos PB = COB (JiM) (010) = 1 .,,,,-^ — -.■.'-:--^ .. ..,-—„, ' , to- — ^ s/Pb'^d^ + A-^a-2(j2 Bin^ /3 -+- i-o'J'^ + Zhlab'-c cos j3 COS PC = COS [hkC) (OOn = 27 lab + Mc COS B s/h'b-e^ + k^a-^c^ sin* fi + l^a-b'^ + 2hlab-c cob /9 460 APPENDIX. (2) The distance between any two planes may be sxpressed in general form, but in all practically arising oases the end can be attained by the solution of one or more spherical tri- angles on the projection. (3) For the relation between the planes in a zone the general equation before given holds good : cot PS - cot PR _ (PQ) . (SR ) cotPQ - cot PR ~ (QR) . (PS)" (4) For all zones passing through the clinopinacoid (010), the value of PR may be taken aa 90°, and the above equation consequently simplified : h _k tanPB _ I J) ~ q ' tan QB ~ r This equation is especially valuable for determining the indices of planes in the prismatio and clinodome series. (5) To determine the axial relations the general equation admits of being transformed so aa to read : h sin PYA p sin QYA a I ' sin PYG ~ r ' sin QYC ■" c. k sin PYA _ q cot PY ~ 7- ■ sin QYA b cotQY ~ c and The angles PYA , PYG are angles which may be calculated directly by spherical triangles from the measured angles. Similarly for QYA, QYC. PY and QY are the angles between the given plane P or Q with the clinopinacoid. VI. Triclinic System. In the TricHnic System, since the axes are unequal and all mutually oblique, there can be no plane of symmetry, and there can in no case be more than two planes included in a single form. The three axes are distinguished as a vertical, c, a longer lateral, or macrodiagonal axis, b, and a shorter lateral, or brachydiagonal axis, a. The position assumed for the axes is shown in f. 259, p. 80. The general symbol {hkl\ , which includes eight similar planes in the orthorhombic system, is here resolved into four independent forms, embracing two opposite planes only. They aie thus : ... [hkl) ,ox {Md) ,ox ijikl) ,.. (hkl) (^) (/ikl) ^^^ (hkl) ^^> (MO ^^> {hkl) These correspond respectively to mF'n (1), rnVn (2), 7nF,Ti (3), m,Fn (4) of Naumann, oi ~m-n , — wi-71, m-n', m-n', as the abbreviated symbols are written in the earlier part of this work. Contrary to the usage in the orthorhombic system, it is customary to make [100] the macropmacoid {i-l — a : rtil : rcc\ and [OlOJ the brachypinacoid (i-i — cou:b: ccc . Planes having the symbol \hO[] are then macrcdo.iaos ; and those of the symbol [Qkl] are brachy- domes. Similarly then pyramids {h > k) of the form [hkl] are macrodiagonal planes, and those of the form {hkl) are brachydiagonal planes. The unit prism consists of two independent foi-ms (110), (iiO) (I=aoP,'), and (110;, (110) (I =« ',P). Mathematical Relations of the Triclinic System, fn consequence of the obliquity of the axes in the Triclinic System the mathematical rela- tions are less simple, and the general equations deduced as before become so complicated as to be seldom of much practiced value. Most problems which arise may be solved by the zonal relations, or by the solution of the spherical triangles in the projection. Some of the most important relations (given by Schrauf) are as follows: miller's system of crystallography. 461 If tho angle between the axes X and Z = tj, between X and Y = C and between Y and Z = I (see f. 757) ; if also a, /3, 7 are the corresponding angles between the pinacoid planes- then • cos I = and where Also cos /3 cos y — cos a sin y3 sin 7 COSTJ = cos^ PX = hWc^ A. cos 7 COS a — COS sin 7 sin a k"a"c- A- cos- PY cosC = cos- PZ = cos /3 c os g — COS •> sin a sin Pa"-¥ A, M. • "^^ Mi ■ ' " Ml Ai = [1 -+- 2 cos a cos i3 cos 7 — (cos- a + cos** /3 + cos"'' 7)]. M) = Ti-b'^a^ sin'^ o + ^'aV sin^ + f-a-5- sin* 7 + 2abG (Mb cos J3 sin o sin 7 + hkc cos 7 sin a sin )3 + kla cos a sin )8 sin 7). cos' AX = A, cos BY = A. sin'' i3 ' cos CZ = A, Bin- 7 805 When PX, PY, PZ have been found by calculation, then the following equation gives the relation of the axes : 4- cos PX = ^ cos PY = -T- cos PZ. h k I As seen in f . 805. cos PX = sin PBC sin PB = sin PCB sin PC cos PY = sin PGA sin PC = sm PAG sin PA cos PZ = sm PAB sin PA = sin PBA sin PB and also from these it follows that — •|- sin PAC = -f sin PAB ; 4- Bin PBA = -^ sin PBC ^ sin PCB = 4-8"! PCA. h ft X = 180° - CAB ; 7j = 180° - ABC ; f = 180° - ACB. Relations of the Six Crystalline Systems in Respect to Symmetry. From a careful study of the spherical projections for the successive systems a very cleai idea may be obtained of the degree of symmetry which characterizes each. It is well under- stood that in the Isometric System there are nine planes of symmetry; in the Tetrngonal, five; in the Hexagonal, seven ; in the Orthorhombic, three; and in the Monoclinic only one. These relations are shown on the projections by the symmetrical distribution of the poles abort the respective great circles. These zone-circles of symmetry are as follows : Isometric System (f . 766) : 1st, the three diametral zones : 3. (010), (001), (010). 1. (100), (010), (100). Also the diagonal zones : 2. (100), (001), (100). 8. 4. (110), (001), (110). 6. (100), (Oil), (100). 5. (liO), (001), (110). 7. (100), (Oil), (iOO). Tetragonal System (f . 790) : 1. (100), (010), (100). 2. (100), (001), (100). Also t 4. (110), (001), (lIO). 5. (110), (001), (110) (010), (101), (010). (010), (101), (OiO). 3. (010), (001), (OlOX 462 APPENDIX. Hexiigonal System (f. 793) : 1. (1010), (0001), (TOlO). 4. (1120), (0001), (1120). Orihorhovihic System (f. 801) 1. (100), (010), (100). M&nodinic System (f. 804) : 2. (0110), (0001), (0110). 5. (1210), (0001), (1210). 7. (1010), (0110), (1100). 1. (100), (001), (TOO). (100), (001), (100). In the Triclinic System there is no plane of symmetry. 3. (ilOO), ((/OOlj, (ITOO). 6. (2110), (0001), (2110). 3. (010), (001), (010). The Rhombohedral Division op Miller. The following projection (f. 806) is added in order to show the relation of the forms in the Hexagonal and Rhombohedral Systems as referred to the three equal oblique axes of Miller. The forms are as follows : The planes having the indices (100), (010), (001) are those of the (plus) funda- mental rhombohedron, while the plane (111) is the base. The planes (221), (121), (122) are those of the minus fundamental rhombohedron ; with the planes (100), (010), (001) they form the unit hexagonal pyramid. The hexagonal unit prism (/= [0110]) has the symbols : (211), (121), (112), (211), (I2i), (112). The second, or diagonal hexa- gonal prism (i-2_= [1120]) has the symbols : (101), (110). (Oil), (101), (110), (Oil). The dihexagonal pyramid embraces, like the simple hexagonal pyramid, two forms, [hkl\ and [^^^J ; the symbol [hkl] hence belongs to the plus scalenohedron, and [efg] to the minus. In this as in other cases it is true that : e— — h + 2k + 21, fr=2h-k + 2l,g^ 2h + 2k-l. The dihexagonal prism includes the six planes of the form [/iA;0] , and the remain- ing six of the form [e/0]. Most of the problems arising under this system can be solved by the zone equations, or by the working out of the spherical triangles on the sphere of projection. APPENDIX B. OH THE DRAWING OF FIGURES OF CRYSTALa In the projection of crystals, the eye is supposed to be at an infinite distance, so that the rays of light fall from it on the crystal in parallel lines. The plane on which the crystal is projected is termed the plane of projection. This plane may be at right angles to the ver- tical axis, may pass through the vertical axis, or may intersect it at an oblique angle. These different positions give rise, respectively, to the horizontal, vertical, and oblique pro- jections. The rays of light may fall perpendicularly on the plane of projection, or may be ohliquely inclined to it ; in the former case the projection is termed orthographic, in the second CLiNOGR.\pnic. In the horizontal position of the plane of projection, the projection is always orthographic. In the other positions, it may be either orthographic or clinographic. It is generally preferable to employ the vertical position and clinographic projection, and this method is elucidated in the following pages. 807 Projection op the Axes. The projection of the axes of a crystal is the first step preliminary to the projection of the form of the crystal itself. The projection of the axes in the isometric system, which are equal and intersect at right angles, is here first given. The projection of the axes in the other systems, with the exception of the hexagonal, may be obtained by varying the lengths of the projected isometric axes, and also, when oblique, their inclinations, as shown beyond. Isometric System. — When the eye is directly in front of a face of a cube, neither the sidee nor top of the cry.-stal are visible, nor the planes that may be situated ou the intermediate edges. On turning the crystal a few degrees from right to left, a side lateral plane is brought in view, and by elevating the eye slightly, the terminal plane becomes apparent. In the following demonstration, the angle of revolution is designated 5, and the angle of the ele- vation of the eye, e. Fig. 807 represents the normal position of the horizontal axes, supposing the eye to be in the direc- tion of the axis BB ; BB is seen as a mere point, while CO appears of its actual length. On revolving the whole through a number of degrees equal to BMB' (5) the axes have the position exhibited in the dotted lines. The projection of the semiaxis MB is now lengthened to MN, and that of the semi- axis MO is shortened to MH. If the eye be elevated (at any angle, «), the lines B'N, BM, and OH will be projected respectively below N, M, and H, and the lengths of these projections (which we may designate 6'N, JM, and c H) wQl be di- rectly proportional to the lengths of the lines B N, BM, and C'H. It is usual to adopt such a revolution and such an elevation of the eye as may be expressed by a simple ratio between the projected axes. The ratio between the two axes, BIN : MH, as projected after the revolution, is designated by 1 : r ; and the ratio of 6'N to ilN by 1 : « Suppose /• to equal 3 and s to equal 3, then proceed as follows : ^ ] a .b' \ i ^ \ N ] r" ^ ;* 4G4 APPENDIX. B B is the pro- 809 Draw two lines AA', H'H (f. 808), intersecting' one another at right angles. Make MH .-= MH' = b. Divide HH' into 3 (?■) parts, and through the points, N, N', thus determined, draw perpendiculars to HH'. On the left hand vertical, set off, below H , a part H'R, equal to— b = — H M; aud from R draw RM, and extend the same to the vertical N'. jection of the front horizontal axis. Draw BS parallel with MH and connect SM. From the point T in which SM intersects BN, draw TC par- allel with MH. A line (CC) drawn from C through M, and extended to the left vertical, is the projection of the side horizontal ax.s. Lay off on the right vertical, a part HQ equal tc -MH, and make MA = MA'= MQ ; A A' is the vertical o axis. If, as here, r = 3, and s = 2, then 5 = 18° 26 , and e = 9° 28', for cot ^ ^r^ and cot e = rs. Tetragonal and rtliorhombie Systems. — The axes AA', CC , BB, constructed in the mannei described, are equal and at right angles to each other. The projection of the axes of a tetra- gonal crystal is obtained by simply laying off, with a scale of proportional parts, on MA and MA' taken as units, the value of the vertical axis (/) for the given species. Thus for zircon, where c = -(Ji, we must lay off "64 of MA above M and the same length below. For an orthorhombic crystal, where the three axes are unequal, the length of c must as before be laid off above and below from M, and that of b to the right and left of M, on CC , MC being taken as the unit. It is usual to make the front axis MB = a = 1. Monoclinic System. — The axes c and d in the monoclinic system are inclined to one another at an obliqe angle — ;8. To project this inclination, and thus adapt the isometric axes to a monoclinic form, lay off (f . 809) on the axis MA, Mrt = SIA cos &, and on the axis BB' (before or behind M, according as the inclination of d on c, in front, is acute or obtuse) M.b = MB x sin j8. From the points b and rt, draw lines parallel respectively with the axes AA' and BB', and from their intersection D', draw through M, D'D, making MD = MD'. The line DD' is the clinodiagonal, and the lines AA, C C, DD re- present the axes in a monoclinic solid in which a = Z* = o = 1. The points a aud b and the position of the axis DD will vary with the angle j3. The relative values of the axes may be given them as above explained ; that is, if d = 1, lay off in the direction of MA and ]VIA a line equal to c, and in the direction of MC and MC a line equal to &, etc. Tridi/dc Syatem. — The vertical sections through the horizontal axes in the triclinic system are obliquely in- clined ; also the inclination of the axis a to each axis b In the adaptation of the isometric axes to the triclinic forms, it is there- fore necessary, in the first place, to give the requisite obliquity to the mutual inclination of the vertical sec- tions, and afterwards to adapt the horizontal axes. The inclination of these sections we may designate A, and as heretofore, the.angle between a and 6, 7, and a and c, ^. BB' is the analogue of the brachydi 'igonal, and CC of the macrodiagoual. An oblique iucliuaiion may be given the vertical sections, by varying the position of either of these fectious. Permitting the brachydiagonal section ABA B' to remain unaltered, we may vary the other sec- tion as follows : Lay off (f. 810) on MB, M6'= MB x cos A, and on the axis C C (to the right or left of M, according as the acute angle A is to the right or left), Mc = MC x sin A ; completing the parallelogram Mb' Dc, and drawing the diagonal MD, extending the same to D' so as to make MD — MD, we obtain the line DD' , the vertical socti on and c, is oblique. 810 ON THE DEAWIXG OF FIGUKES OF CRYSTALS. 4G5 passing through this line is the correct macrodiagonal section. The inclination of a to the new macrodiagonal DD' is still a right angle ; as also the inclination of , their oblique inclinations may be given them as follows: Lay oif on MA (f. SlOj, M^ = ^lA x cos P, and on the axis BB (brachydiagonal), ^Ib — MB' x sin 0. By completing the parallelogram 'Mrr,. "E'b, the point E is determined. Make ME = !ME; EE is the projected brachydiagonal. Again lay off on MA, Ma'= MA x cos a. and on 3ID , to the left. M(^ = MD x sin o. Draw lines from a' and d jiarallel to MD and MA ; F . the intersection of these lines, is one extremity of the m.-.crodiagonal ; and the line FF . in which MF = MF , is the macrodiagonal. The vertical a.^is AA and the horizontal axes EE (brachydiagonal) and FF (macrodiagonal) thus obtained, are the axes in a triclinic form, in which a = b — c = 1. Different values may be given these axes, according to the method heretofore illu.sti'ated. Hexagonal Syntem. — In this system there are three equal horizontal axes, at right angles tjectio>i. —The process of determining the diiection of the intersection -edges is much simplified if the principles of Quenstedt's Projection (p. 5o) are made use of. In other words, the symbol of every plane is so transformed that for it lli ^ length of the vertical axis is vniti/. This extremity of the vertical axis is then <»ie point of intersection for all planes whatsoever, and the second point will always lie in the horizontal plane, that of the lateral axes. The change in the symbol requires nothing but that the symbol, expressed in full, should be divided by the coefficient of the vertical axis. The direc- tion of each intersection-edge, when determined, is transferred to the figure in process of construction by means of a small triangle sliding against a ruler some 8 inches in length. It will be found in practice that, especially when this method is employed, it is not necessary to actually draw all the lines representing each plane, but to note simply the required points of intersection. This method and its advantages (see Klein, Einleitung in die Krystallberech- nung, II„ p. 387) will be made clear by an example. It is required to project a crystal of andalusite of prismatic habit, showing also the planes i-'l, ^-^, l•^", 1, 3-i, 1-4, and 0. It is evident that an indefinite number of figures may be made, including the planes men- tioned, and yet of very different appearance according to the relative size of each. It is usually desirable, however, to represent the actual appearance of the crystal in nature, only in ideal symmetry, hence it is very imi)ortant in all cases to have a sketch of the crystal to be represented, showing the relative development of the different planes. If this sketch is made with a little care, so as to show also the parallelism of the intersection-edges in the occurring zones, it will give material aid. The zones, it is to be noted, are a great help in drawing figures of crystals, and they should be carefully studied, since the common direction of the intersection-edge once determined for any two planes in it, will answer for all others. The first step is to take the projection of the isometric axes already made once for all on a conveniently large scale, and which, as before suggested, is kept on a card of large size, and ready to be pierced through on to the paper employed. These axes, now of equal length, must be adapted to the species in hand. For andalusite the axial ratio is i- : h : ' — 0'712 : 1"014 : 1 ; hence the vertical axis c must have a length "71 of what it now has, and the lateral axis one 1 "01 ; these required lengths are determined in a moment with a .scale of equal parts The next step is to draw the predominating form, the prism /. Obviously its intersection- edges are parallel to the vertical axis, and its basal edges, intersecting 0, are parallel to ps, tq in the projection (f. 820). The planes i-t, and i- 2 are now to be added, whose inter.'-ectious with each other and with I are parallel to c. The position of one edge, I, i-2, having beau taken, that of the other on the other side is determined by the point where a line parallel tc 470 APPENDIX. the axis h meets the basal edg« of the pri?m. Similarly the position of the same prisniatio edges behind are given by the intersection of lines from front to roar parallel to the axis ?. The prisms drawn, it remains to add the terminal planes, and as they thus nifrflify one an- other's position, they are drawn together. The required intersection-lines are eri.sily obtained. The macrodome l-l is the plane passing through the point c and intersecting the horizontal plane in the line jxiq ; this line is obviously the direction of its intersection-edge with i-i and with 0. The prism ^-2 appears (f. 820) as the two lines ?«/«', tin ; the line van produced beyond m meets pnq at 2, this will be one common point for the two planes 1-7 and i-~l ; the second common poirt is, as always, the point c, hence the line joining these two points, trans- ferred to the crystal in the way described, gives the required intersection- edge for i-i and 1-i. Similarly for i-'l on the right, the two points of intersection are f, and the point where n n and gry), produced, meet, and this gives the second intersection-edge. The planes l-l and 1 (right) meet at d and c ; hence the line cd gives the direction of their in' ersection-edge, whic-l is also the direction of that of 1-i and 1 (left), and of 1 and 2-^_, right and left on both sides. Still again, the plane 2-i^ has the full symbol 2 • : 6 : 2 7. or c : -J-i : d ; and hence intersects the horizontal plane (f. 820) in the lines as (right), nt (left), and n'q, a'p (behind). Hence the intersection-edge of 7. 2-2, l-l has the direction of the line joining the points c and s (right), and similarly to the left and behind. The intersection- edge of 2-2 front, and 2-2 behind, haa the direction of the line joining the points c and x (right) and c and y (left). The method of obtaining the intersection-edges of the planes will be clear from this ex- ample. Practical facility in drawing figures by this or any other method is only to be obtained by practice. It will be found that at almost every step there is an opportunity to test the accuracy of the work — thus every point of intersection on the basal plane behind must lie on a line drawn from the cor- responding point in front on the basal plane, in the direction of the axis n ; so, too, the point of intersection of 2-2 and 1 (front), 2-2 and 7 (behind), on one side, must be in the line of the horijzontal axis {b) with that on the other side, and similarly in other cases. If it were required, as is generally necessary, to complete the form (f. 821) below, it is unnecessary to obtain any new intersec- tion lines, since every line above has its corresponding line oppo- site and parallel to it bdlow. Moreover, in an orthorhombic crys- tal every point above has a corresponding point below on a line parallel to the vertical axis. This, as above, will serve as a control of the accuracy of the work. There is another method of drawing complex crystalline forms which has many advantages and is sometimes to be preferred to any other; it can be explained in a very few words. After the axes have been obtained the diametral prism is constructed upon them. Upon the solid angles of this each plane of the required form is laid off, the edges being taken instead of the 822 823 824 iixe.s. Suppose that f. 822 represents the diametral prism of an orthorhombic crystal Here obviously the edge e — 2 ', e = 2*'', ^ = 2 7. The plane 1 ('• : h : o) may be laid off on it by lalung from the angle a equal portions of the edges e, e, e, for instance, conveniently one ON THE DRAWING OF FIGURES OF CRYSTALS. 471 half of each, heuce the plane appears as mno. Again the plane 2 (2« : 5 : «) is laid off by taking the unit lengths of the edges e (/>), and e (u) and twice the unit length of e (y), the plane ia then irmb. Again, the plane 4-5 (4r : b : 2\) takes the position npb^ since ap = 2';, ap = iA, and an = u, the ratio of the edges (axes) being the same as in the symbol. So also the plane 2-2 (2(5 : 2^ : u) has the position rmo, since ao = (', am = b, and ar = ^z, here, too, the ratio of the axes being preserved. By plotting the successive planes of the crystal in this way, each solid angle corresponding to an octant, the direction of the intersection-edge.s for the given form are at once obtained. For example, the inter.section-edge for 1, and the basal plane, as also for 1 and 2, it is the line mil ; for 1 and 4-5 it is the dotted line joining the comiaou points n and a ; for 1 and 2-2 it is the line mo ; for 2 and 4-5, also for 2 and 2-2, it is the line joining the common points fix. The direction of the required intersection-edges being obtained in this way, they are used to construct the crystal itself, being transferred to it in the usual way. In f. 823 they have been placed upon the diametral prism, and when this process has been completed for the other angles, and, too, the domes e\ e', are added, the form in f. 824 results. On the Drawing op Twin Crystals. In order to project a compound or twinned crystal it is generally necessary to obtain first the axes of the second individual, or semi-individual, in the position in which they are brought by the revolution of 180". This is accomplished in the following manner. In f. 825 a com- pound crystal of staurolite is represented, in which twinning has taken place (1) on an axis normal to 3-1, and (2) on an axis normal to f-^^. The second, being the more general case, is of the greater importance for the sake of example. In f. 825, cc', bb', aa' represent the rect- an^lar axes of staurolite (c = 1 -441, b — 2112, a = 1). The twinning-plane f-| (fc : —b : |a) 825 has the position MNR. It is first necessary to construct a normal from the centre to thia {)lane. If perpendiculars be drawn from the centre to the lines MN, NR, WSi, they will meet them at the points z, y^ 2, dividing each line into segments proportional to the squares of the adjacent axes ;* or Na; : Ma; = ON' : OM'. In thLs way the points x, y, z are fixed, and lines * This is true since the axial angles are right angles. In the Monoclinic System two of the axial intersections are perpendicular, and they are sufficient to allow of the determina- tion of the point T, as above. In the Triclinic System the method needs to be slightly modified. 472 APPENDIX. drawn from any two of them to the opposite angles R, N, or M will fix the point T. A line joining T and O is normal to the plane (MNR = J-^). Furthermore, it is obvious that if a revolution of 180' about TO take place, that every point in the plane MNR will remain equally distant from T. Thus, the point M will take the place ^(MT = T/.i), the point b' the place y3' (XT— T)3'), and so on. The lines joining these poiuts ;u, 0', x, and the common centre will be the new axes corresponding to MO, NO, RO. In order to obtain the unit axes corresponding to /•, l>, a it is merely necessary to draw through c a line parallel to MT/x, meeting /xO at 7, then 7O7' is the new vertical axis con-esponding to cOc , also fiOfi corresponds to bOb', and aOa' corresponds to aOd'. These three axes then are the axes for the second individual in its twinned position ; upon them, in the usual way, the new figure may be constructed and then transferred to its proper position with reference to the normal crystal. For the second method of twinning, when the axis is normal to |-?, the construction is more simple. It is obvious the axis is the line Oa;, and using this, as before, the new axes are found ; kOk corresponds to cOc' (sensibly coinciding with bb ), since A f-* = 134 21', and so on. In many cases the simplest method is to construct first the normal crystal, then draw through its centre the twtnning-plane and the axis of revolution, and determine the angular points of the reversed crystal in the principle alluded to above: that by the revolution every point remains at the same distance from the axis, measured in a plane at right angle to the axis. Thus in f. 827 when the scalenohedron has been drawn, since the twiuning-plane is the basal plane, each angular point, by the revolution of 180', obtains a position equidistant from this plane and directly below it. In this way each angular point is determined, and the oo.m- pound crystal is completed in a moment. Calcite. APPENDIX C. CATALOGUE OF AMERICAN LOCALITIES OF MINERALS. The following catalogue * may aid the mineralogical tourist in selecting his routes and arranging the plan of his journeys. Only important localities, which have afforded cabinet specimens, are in general included; and the names of those minerals which have been obtained in good specimens are distinguished hij italics, the addition of an exclamation mark (!), or of two (!!), indicates the degree of excellence of the specimens. Many of the localities mentioned have been exhausted, others will now yield good specimens only when further explored with blasting, etc. In general, only those of the localities mentioned can be relied upon as likely to reward the\isitor liberally where active work is being continually carried on. MAINE. Ai-BANY. — Beryl! green and black tourmaline, feldspar, rose quartz, rutile. Aroostook. — Red hematite. Auburn. — Lepidolite, amblygonite {hebronite), green tmirmaliju. Bath. — Vesuvianite, garnet, magnetite, graphite. Bethel. — Cinnam,on garnet, calcite, sphene, beryl, pyroxene, hornblende, epidote, graphite, talc, pyrite, arsenopyrite, magnetite, wad. Bingham. — Massive pyrite, galenite, blende, andalusite. Blue Hill Bat. — Arsenical iron, molybdenite ! galenite, apatite! fluorite! black tourma- line (Long Cove), black oxide of manganese (Osgood's farm), rhodonite, bog manganese, wolframite. BowDoiN. — Rose quartz. BowuoiNHAXi. — Beryl, molybdenite. Brunsw^ick. — Oreenmica, garnet! black tourmaline! molybdenite, epidote, calcite, mu» covite, feldspar, beryl. BucKPiELD.— -Garwe^ (estates of Waterman and Lowe), iron ore, muscotite! tourmaline^ magnetite. Casidage Farm. — (Near the tide mills), molybdenite, wolframite Camden. — Made, galenite, epidote, black tourmaline, pyrite, talc, magnetite. Caumel (Penobscot Co.). — Stibnite, pyrite, made. CoRiNNA. — Pyrite, arsenopyrite. Deer Isle. — Serpentine, verd- antique, asbestus, diallage, magnetite. Dexter. — Galenite, pyrite, blende, chalcopyrite, green talc. DiXFiELD. — Native copperas, graphite. East Woodstock. — Muscovite. Far.mingtok. — (Norton's ledge), pyrite, graphite, bog ore, garnet, staurolite. Fkeeport. — Hose quartz, garnet, feldspar, scapolite, graphite, miiscomte. Fryeburg. — Gurnet, beryl. Georgetown. — i Parker's island), ben'yl! black tourmaline. Greenwood. — Graphite, black manganese, beryl! arsenopyrite, cassiterite, mica, rost quartz, garnet, corundum, albite, zii'con, molybdenite, magnetite, copperas. * The catalogue is essentially the same as that published in the 5th Edition of Dana's Sya tern of Mineralogy. 1868. The names of a considerable number of new localities have been added, however, which have been derived from various printed sources, and also from privata contributions from Prof. G. J. Brush, Mr. G. W Hawes, Mr. J, Willcox, and others. See further on pp. 503 to 508. 474 APPENDIX. Hebron. — Cassiterite, arsenopyrite, idocrase, lepidoUte, amblt/gonite {7iebron'te), rubeUiUl indicolite, green tourmaline, mica, beryl, apatite, albite, childrenite, cookeite. Jkwell's Island.— Pyrite. Kataiidin Ikon Wouks. — Bog-iron ore, pyrite, magnetite, quartz. Lktteu E, Oxt'ord Co. — Staurolite, made, copperas. Linnaeus. — Hematite, limonite, pyrite, bog-iron ore. LiTCUFiELD. — iSudalite, cancrinite, ela'oUte, zircon, spodumene, muscovite, pyrrhotite. LuBEC Lead Minks. — Galeidie, chalcuqiyrile, blende. MACHiASPOitT. — Ja,'*y)fr, epidote, laumontite. Madawaska Settlements. — Vivianite. Ml NOT. —Beryl smoky quartz. MoNMODTii. — Actinolite, apatite, elo'oUte, zircon, staurolite, plumose mica, beryl, rutile. Mt. Aeraiiam. — Andnlusite, staurolite. NoHWAY. — Chrysoberyl ! molybdenite, beryl, rose quartz, ortlioclase, cinnamon garnet. Ork's Island. — Steatite, garnet andalusite. Oxford. — Garnet, beryl, apatite, wad, zircon, muscovite, orthoclase. PAiiis. — Green! red! black, and blue tourmaline! mica! lepidoUte! feldspar, albite, quarti crystals ! rose quartz, cussiterite, aniblygonite, zircon, brookite, beryl, smoky quartz, spodu- mene, cookeite, Jeucoijyrite. Paksonsfield. — Vesuvianite ! yellow gam et, pargasite. adularia, scapoliie, galenite, blende, chalcopyrite. Peru — Crystallized pyrite. PniPi'SBURG. — Yellow garnet ! tnanganesian garnet, vesuvianite, pargasite, axinite, laumon- tite ! chabazite, an ore of cerium ? Poland. — Vesuviauite, smoky quartz, cinnamon garnet. Portland. — Prehnite, actinolite, garnet, epidote, amethyst, calcite. PowNAL. — Black tourmaline, feldspar, scapolite, pyrite. actinolite, apatite, rose quartz. Raymond. — Magnetite, scapolite, pyroxene, lepidoUte, tremolite, hornblende, epidote, orihC' clase, yellow garnet, pyrite, vesuvianite. Rockland. — Hematite, tremolite, quartz, wad, talc. Rumford. — Yellow garnet, vesuvianite, pyroxene, apatite, scapolite, graphite. Rutland. — Allanite. Sandy River. — Auriferous sand. Sanpord, York Co. — Vesuvianite ! albite, calcite, molybdenite, epidote, black tourmaJine, labradorite. Searsmont . — Andalusite, tourmaline. South Berwick. — Made. Standish. — Columbite ! Streaked Mountain. — Beryl! black tourmaline, mica, garnet. Tuomaston. — Calcite, tremolite, hornblende, sphene, arsenical iron (Owl's head), black- manganese (Dodge's mountain), thomsonite, talc, blende, pyrite, galenite. Topsuam. — Quartz, galenite, blende, tungstite ? beryl, apatite, molybdenite, columbite. Union. — Magnetite, hog-iron ore. Wales. — Axinite in boulder, alum, copperas. Waterville — Crystallized pyrite. Winduam (near the bridge). — Staurolite, spodumene, garnet, beryl, amethyst, eyanite, tourmaline. WiNSLO w. — Cassiterite. WiNTiiROP. — Staurolite, pyrite, hornblende, garnet, copperas. Woodstock. — Oraphite, hematite, prehnite, epidote, calcite. YoBK. — Beryl, vivianite,, oxide of manganese. NEW HAMPSHIRE. AcwoKTn. — Beryl!! mica! tourmaline, feldspar, albite, rose quartz, columbite! cyanite, autunite. Alstead. — Mica! ! albite, black tourmalivbe, molybdenite, andalusite, staurolite. Amherst. — Vesuvianite, yellow garnet, pargasite, calcite, amethyst, magnetite. Bartlett. — Magnetite, liematite, brown iron ore in large veins near Jackson (on " Bale face mountain "), quartz crystals, smaky quartz. Bath. — Galenite, chalcopyrite. Bedford. — TremoUte, epidote, graphite, mica, tourmaline, alum, qaartz. Bellows Falls. — Cyanite, staurolite, wavelJite. Bbistol. — Oraphite. AMERICAN LOCALITIES. 475 Camp"0"". — Beryl! Cana.an. — Gold in pyrites, garnet. Chakleston. — StauroUte made, andnlimte made, bog-iron ore, prehnite, cyanite. CoRNi,;ii. — Stibnite, tetrahedrite, rutile in quartz! (rare), stauroUte. Croyd':n. — loUte ! chalcopyrite, pyrite, pynrhotite, blonde. Enfiei D. — Gold, galenite, staurolite, green quartz. FitANciJSTON. — Soapsto/ie, arseuopyrite, quartz crystals. FnAN<"<'MA. — Hornblende, stauroUte! epidote! zoisite, hematite, magnetite, black and red manga.iesiAin cpirnets, arseuopyrite {danaite), chalcopyrite, molybdenite, prehnite, green quartz, mtAachite, azurite. GiLFOK.') (Gunstock Mt.). — Magnetic iron ore, native "loadstone." Goshen — Oraphite, black tourmaline. GiLMANTOWN. — Tremolite, epidote, muscovite, tourmaline, liinonite, red and yellow quartz crystals. GiiAFTOX. — Mica! (extensively quarried at Glass Hill, 2 m. S. of Orange Summit), albitef blue, ^'reen. and yeUow brn-yls! (1 m. S. of 0. Summit), tourmaline, garnets, triphyiite, apa- tite, fluorite. Grantuam.— Oray staurolite ! Groton. — Arsenopyrite, blue beryl, muscovite crystals. Hanover. — Garnet, a boulder of qu.irtz containing rutile ! black tourmaline, quartz, eya- n\te, labradorite, epidote. Haveriii-Ll. — Garnet! arsenopyrite, native arsenic, galenite, blende, pyrite, chalcopy- rite, magnetite, marcasite, steatite. HiLLSBORO' (Campbell's mountain). — GrapJdte. Hinsdale. — Jihodomte, black oxide of manganese, molybdenite, indicolite, black tour- maline. Jackson. — Drusy quartz, tin ore, arsenopyrite, native arsenic, fluorite, apatite, magnetite, molybdenite, wolframite, chalcopyrite, arsenate of iron. Japprey (Monadnock Mb.). — Cyanite, limonite. Keene. — Graphite, soapstone, milky quartz, rose quartz. L\ND.\FP. — Molybdenite, lead and iron ores. Leij.\non. — Bog-iron ore, arsenopyrite, galenite, magnetite, pyrite. Lisbon. — Staurolite, black and red ^r^uviete, granular magnetite, hornblende, epidote, zoiaite^ h?jmatite, arsenopyrite, galenite, gold, ankerite. Littleton. — Ankerite, gold, bornite, chalcopyrite. malachite, menaccanite, chlorite. Lyman. — Gold, arsenopyrite, ankerite, dolomite, galenite, pyrite, copper, pyrrhotite. Lyme. — Cyanite (N. W. part), black tourmaline, rutile, pyrite, chalcopyrite (E. of E. vil- lage), stibnite, molybdenite, cassiterite. Madison. — Galenite, blende, chalcopyrite, limonite. Merrimack. — Rutile! (iu gneiss nodules in granite vein). MiDDLETowN. — Jlutile. Monadnock Mountain. — Andalusite, hornblende, garnet, graphite, tourmaline, ortho- clase. Moosilauke Mt. — Tourmaline. MouLTONBOROUGH (Red lli]\).—IIornbende, bog ore, pyrite, tourmaline, Newington. — Garnet, tourmaline. New London. — Beryl, molybdenite, muscovite crystals. Newport — Molybdenite. Or.\nge. — Blue beryls! Orange Summit, chrysoberyl, mica (W. side of mountain), apatite, galenite, limonite. Orford. — Brown tourmaline (now obtained with difficulty), steatite, rutile, cyanite, brown iron ore, native copper, malachite, galenite, garnet, graphite, molybdenite, pyrrhotite, mela- couite, chalcocite, Hpidolite. Pelham. — Steatite. Piermont. — Micaceous iron, barite, green, white, and brown mica, apatite, titanic iron. Plymocth. — Columbite, beryl. Richmond. — lolite! rutile, steatite, pyrite, anthophyllite, talc. Rye. — Ghiastolite. Saddleback Mt. — Black tourmaline, garnet, spinel. SiiEiiBORNE. — Galenite, black blende, chalcopyrite, pyrite, pyrolusite. Springfield.— Beryls (very large, eight inches diameter), manganesian garrieta! black touiinaline ! in mica slate, albite, mica. Sdli,ivan. — Tourmaline (black), in quartz, beryl. Surrey. — Amethyst, calcite, galenite, limonite, tourmaline. SwANZEY (near Keene). — Magnetic iron (in masses in granite). 476 APPENDIX. Tamworth (near White Pond).— Galenite. Unity (estate of James Neal). — C(ypper and iron pyrites, ehlorophyUite, green mCca, radt ated nctinoUte, garnet, titaniferous iron ore, magneiite, tourmaline. Walpole (near Bellows Falls). —Made, staurolite, mica, graphite. ' Ware. — Grapliite. Warki;n. — Chalcfypyrite, blende, epidote, quartz, pyrite, trotwlite, gnleniu, rutile, talc, molybdenite, cinnamoa stone ! pyroxene, hornblende, heryl, cyanite, tourmaline (massive). Watekville — Labradorite, chrysolite. Westmoreland (south part). — Molybdenite ! apatite! blue fddapar, bog inanorineHe (north village), quartz, fluorite, chalcopyrite. oxide of molybdenum and uranium. White Mts. (Notch near the "Crawford House").— Green octahedral fluoiice, quarta crystals, black tourmaline, chiastohte, beryl, calcite, amethyst, amazonstone. WiLMOT. —Beryl. Winchester. — Pyrolusite, rhodochrosite, psilomelane, magnetite, granular quartz, spodu- mene. VERMONT. Addison. — Iron sand, pyrite. Albdrgh. — Quartz crystals on calcite, pyrite. Athens. — Steatite, rhomb spar, actinolite, garnet. Baltimor e. — Serpentine, pyrite I Barnet. — Graphite. Belvidere.— Steatite, chlorite. Bennington. — Pyrolusite, brown iron ore, pipe clay, yellow ochre. Berkshire. — Epidote, hematite, magnetite. Bethel. — Actinolite! talc, chlorite, octahedral iron, rutile, brown spar in steatite. Brandon. — Braunite, pyrolusite, psilomelane, limonite, lignite, white clay, statuary marble ; fossil fruits in the lignite, graphite, chalcopyrite. Brattleborough. — Black tourmaline in quartz, mica, zoisite, rutile, actinolite. scapolite, epodumene, roofing slate. -» Bridgewater. — Talc, dolomite, magnetite, steatite, chlorite, gold, native copper, blende, galenite. blue spinel, chalcopyrite. Bristol. — Rutile, limonite, manganese ores, magnetite. Brookpield. — Arsenopyrite. pyrite. Cabot. — Garnet, staurolite, hornblende, albite, - Castleton. — Baojing sJate, jasper, manganese ores, chlorite. -^ Cavendish. — Garnet, serpentine, talc, steatite, tourmaline, asbestus, tremolite. Chester. — Asbestus, feldspar, chlorite, quartz. Chittenden. — Psilomelane, pyrolusite, brown iron ore, hematite and magnetite, galenite, iolite. » Colchester. — Brown iron ore, iron sand, jasper, alum. Corinth. — Chalcopyrite (has been mined), pyrrhotite, pyrite, rutile, quartz. Coventry. —Rhodonite. Craptsbury. — Mica in concentric balls, calcite, rutile. Derby. — Mica {(uknnsite). Dummerston. — Rutile, roofing slate. Fair Haven. —Hoofing slate, pyrite. Fletcher. — Pyrite, magnetite, acicular tourmaline. Grapton. — The steatite quarry referred to Grafton is properly in Athens ; qiiartz, acti* nolite. Guilford. — Scapolite, rutile, roofing slate. Hartford. — Calcite, pyrite! cyanite in mica slate, quartz, tourmaline. Irasburgh. — Rhodonite, psilomelane. Jay. — Chromic iron, serpentine, amianthus, dolomite. Lowell. — Picrosmine, amianthus, serpentine, cerolite, talc, chlorite. Marlboro'. — Rhomb sjyar, steatite, garnet, magnetite, chlorite. Mendon. — Magnetic iron ore. Middlebury. — Zircon. Middlesex.— Rutile ! (exhausted). "Mo^K-ro^.— Pyrolusite, brown iron ore, pipe clay, feldspar. Morftown. — Smoky quartz! steatite, talc, wad, rutile, serpentine. Morristown. — Galenite. Mount Holly. — Asbestus, chlorite. New Fane. — Olassy and asbestiform actinolite, steatite, green quartz (called cbrysoprnM AMERICAN LOCALITIES. 477 at the locality), chalcedony, drusy quartz, garnet, chromic and titanic iron, rhomb tpar^ serpentine, rutile. "SoViVfiCTL.—ActinoUte, feldspar, broion spar in talc, cyanite, zoisite, chalcopyrite, pyrita PiTTSFOUD. — Brown iron ore, manganese ores. Plymouth. — Siderite, magnetite, hematite, gold, galenite. Pltmpton. — Massive hornblende. Putney. — Fluorite, brown iron ore, r^itile, and zoisite, in boulders, staurolite. Reading. — Glassp nctinoUte in talc. ^ — Readsboro'. — Ulasst/ actinolife, steatite, hematite. RiPTON. — Brown iron ore, augite in boulders, octahedral pyrite. Rochester. — Jlutile, hematite cryst., magnetite in chlorite slate. Rockingham (Bellows Falls). — Cyanite, indicolite, feldspar, tourmaline, fluorite, caioite, jffehnite. staurolite. RoxBURY. — Dolomite, tale, serpentine, asbestus, quartz. Rutland. — Ma gnesite, "white marble, hematite, serpentine, pipe clay. Salisbury. — Brown iron ore. Sharon. — Quartz crystals, cyanite. Shoreham.— /'^/yVc, black marble, calcite. Shrewsbury. — Magnetite and chalcopyrite. Starksboro'. — Bro^vn iron ore. Stirling. — Chalcopyrite, talc, serpentine. Stockbridge — Arsenopyrite, magnetite. y- r::=:;STR afford. — Magnetite and chalcopyrite (has been worked), native copper, hornblende, ^ ^ copperas. Thetford. — Blende, galenite, cyanite, chrysolite in basalt, pyrrhotite, feldspar, roofing slate, steatite, garnet. Townsiiend. — Actinolite, black mica, talc, steatite, feldspar. Troy. — Magnetite, talc, serpentine, picrosmine, amianthus, steatite, one mile southeast of village of South Troy, on the farm of Mr. Pierce, east side of Missisco, chromite, zaratito. Veushire. — Pyrite, chalcopyrite, tourmaline, arsenopyrite, quartz. Wardsboro'. — Zoisite, tourmaline, tremolite, hematite. _. Warren. — Actinolite, magnetite, wad, serpentine. Waterbury. — Arsenopyrite, chalcopyrite, rutile, quartz, serpentme. Waterville. — Steatite, actinolite, talc. - Weathersfield. —Steatite, hematite, pyrite, tremolite. Wells' River.— Graphite. Westfieli). — Steatite, chromite, serpentine. Westminster. — Zoisite in boulders. Windham. — Glassy actinolite, steatite, garnet, serpentine. Woodbury. — Massive pyrite. Woodstock. —Quartz crystals, garnet, zoisite. MASSACHUSETTS. AliPORD. — Galenite, pyrite. Athol. — Allanite, fibrolite (?), epidote! babingtonite ? Auburn. — Masonite. Barre. — Rutile! mica, pyrite, beryl, feldspar, garnet. Great Barrington. — Tremolite. Bedford. — Oarnet. B K LCHE rton. — Allanite. Bern.'^rdston. — Magnetite. 1^/ Beverly. — Columbite, green feldspar, cassiterite. r Blanford. — Serpentine, anthophyllite, actinolite! chromite, cyanite, rose quartz ill boulders. Bolton. — ScapoUte ! petalite, sphene, pyroxene, niittalite, diopside, boltonite, apatite, mag* nesite. rhomb spar, allanite, yttrocerite ! cerium ochre? (on the scapolite). spmel. Boxborough. — Scapolite, spinel, garnet, augite, actinolite, apatite. Brighton. — Asbestus. / Brimfield (road leading to Warren).— ifiiYe, adularia, molybdenite, mica, garnet / /^ Carlisle. — Tourmaline, garnet! scapolite, actinolite. ^ Charlestown. —Prehnite, laumontite, stilbite. chabazite, quartz crystals, melanolite. Chelmsford. — Scapolite (chelmafordite), cJumdrodite, blue spinel, aminnt/iua! toMb quartz. 478 APPENDIX. Chjjster. — Hornblende, scapoltte, zoisite, spodnmene, indieolite, apatite, magnetite, cliro- mite, Btilbite, heulandite, analcite and chabazite. At the Emery Mine, Chester Factories.— C&rundum, margnrite, dianpore, epidote, corundophilite, chloritoid, tourmaline, menaccaU' Ue ! nitile, biotite, indianite? andesite ? eyanite, amesite. CHESTKUPIET-D. — Blue, green, and red tourmnUne, cleavelnndite (albite), lepidolite, smok^ quartz, microlite, sjwdiimene, ci/anife, apatite, 7vse beryl, garnet, quartz crystals, stnurolite^ cassiterite, cokimbite, zoisite, uranite, brookite (eumanite), scheelite, anthophyllite, boinite. Conway.— Pyroiusite, fluorite, zoisite, rutile ! ! native alum, galenite. CUMMINGTON. — Rhodonite! cummingtonite (hornblende), marcasite, garnet. Dedham. — Asbestus, galeuite. Deerfiei,d. — Chabazite, heulandite, stilbite, amethy.st, carnelian, chalcedony, agute. FlTCHBURG (Pearl Hill). — Beryl, staurolite! garnets, molybdenite. FoxBOROUGii. — Pyrite, anthracite. Franklin. — Amethyst. Goshen. — Mica, albite., spodvmene! blue and green tourmaline, beryl, zoisite, smoky quartz, colnmbite, tin ore, galenite, beryl (goBhenite), pihlite (cyraatolite). Greenfield (in sandstone quarry, half mile east of village). — AUophane, white and greenish. Hatfield. — Barite, yellow quartz crystals, galenite, blende, chalcopyrite. Hawley. — Micaceous iron., massive pyrite, magnetite, zoisite. Heath. — Pyrite, zoisite. Hinsdale. — Brown iron ore, apatite, zoisite. Hubbardston. — Massive pyrite. Lancaster. — Cyanite, chiastoUte! apatite, staurolite, pinite, andalusite. Lee. — Tremolite! sphene! (east part). Lenox. — Brown hematite, gibbsite(?) Lkverktt. — Barite, galenite, blende, chalcopyrite. ,;:^Leyden. — Zoisite, rutile. LiTTLEFiELD. — Spinel, scapolite, apatite. Lynnfiei,d. — Magnesite on serpentine. Martha's Vineyard. — Brown iron ore, amber, selenite, radiated pyrite. Mendon. — Mica! chlorite. Middlefield. — Glassy actinoUte, rhomb spar, steatite, serpentine, feldspar., drusy quarti, apatite, zoisite, nacrite, chalcedony, talc! deweylite. Milijury. — VermicuUte. Montague. —Hematite. Newbury. — Serpentine, chrysotile, epidote, massive garnet, siderite. Newburyport. — Serpentine, nemalite, uranite. — Argentiferous galenite, tetrahedrite, chalcopyrite, pyrargyrite, etc. New Braintree. — Black tourmaline. :=^'NoiiVficn.— Apatite ! black tourmaline, beryl, spodumme! tyiphylite (altered), blende, quartz crystals, cassiterite Northfield. — Columbite, fibrolite, cyanite. Palmer (Three Rivers). — Feldsjmr, prehnite, calc spar. Pelham.— J,s7)fstM«, serpentine, quartz crystals, beryl, molybdenite, green hornsUme, epidote, araethvst, corundum, vermiculite (pelhamite). Plainfield. — Cummingtonite,, pyroiusite, rhodonite. Richmond. — Brown iron ore, gibbsite! alloj)hane. Rockport. — Danalite, cryophylUte., annite, cyrtolite (altered zircon), green and icJiite oi-tho- tlase. RoWE. — Epidote, talc. South Royalston.— .Bej-^L^.^ (now obtained with great difficulty), mica! ! feldspar I ftllanitc. Four miles beyond old loc, on farm of Solomon Hey wood, mica ! beryl! jeldsparl menaccanite. RussEL —Schiller spar (diallage ?), mica, serpentine, beryl, galenite, chalcopyrite. Salem. — In a boulder, cancrinite, sodalite, elaeolite. Saugus. — Porphyry, jasper. ^ilK¥ViKi.V) .— A.''««k/<l\n . — Dolomite. Dover. — Dolomite, tremolite, garnet (Fc^s ore bed), staurolite, lim/mite. FiSHKiLi,. — Dolomite; near Peckville, talc, asbestus, gra/phite, hornblende, augite, cietino- lite, hydrous anthophyllite, Umonite. North East. — Chalcocite, chalcopyrite, galenite, blende. Pawling. — Dolomite. Rhinebeck. — Calcite, green feldspar, epidote, tourmaline. Union Vale. — At the Clove mine, gibbsite, Umonite. ESSEX CO. — Alexandria. — Kirby's graphite mine, grapJiite, pyroxene, seapoUte, sphene. Crown Point. — Apatite (eupyrchroite of Emmons), bj-own tourmaline! in the apatite, chlorite, quartz crystals, pink and blue calcite, pyrite ; a short distance south of J. C. Ham- mond's liouse, garnet, scapoUte, chalcopyrite, aventurine feldspar, zircon, magaetie iron (Peru), epidote, mica. Kekne. — Scapohte. Lkwis.— Tabular spar, colopJionite, garnet, labradorite, Iiornblende, actinolite; ten milea south of the village of Keeseville, mispickel. Long Pond. — Apatite, garnet, pyroxene, idocrase, coccoUte! / scapoUte, magnetite, blue calcite. McIntyre. — Labradorite, garnet, magnetite. Moriah, at Sandford Ore Bed. — Magnetite, apatite, aManite ! lanthanite, actinolite, and feldspar ; at Fisher Ore Bed, magnetic iron, feldspar, quartz ; at Hall Ore Bed, or "New Ore hed.''^ jnagnetite, zircons; on Mill brook, calcite, pyroxene, hornblende, albite; in the town of Moriah, magnetite, black mica ; Barton HUl Ore Bed, albite. Newco.mb. — Labradorite, feldspar, magnetite, hypersthene. Port Henry. — Brown tourmaline, mica, rose quartz, serpentine, green and black pyroxene, hornblende, cryst. pyrite, graphite, wollastonite, pyrrhotite, adularia ; phlogopite ! at Cheevei Ore Bed, with magnetite and serpentine. Roger's TXoc^. — Graphite, wollastonite, garnet, colopJionite, feldspar, adxAaxia,, pyroxene, aphenc, coccolite. Schrdon. — Calcite, pyroxene, chondrodite. Ticonderoga. — Graphite! pyroxene, sahlite, spliene, black tourmaline, cacoxene? (Mt Defiance). Westport. — Labradorite, prehnite, magnetite. Willsboro'. — Wollastonite, colophonite, garnet, green coccolite, hornblende. ERIE CO.— Elltcott's HIilIjS.— Calcareous tufas. 31 482 A.rPENDix. FRANKLIN CO.— Chateaugay. — Nitrogen springs, calcareous tnfu. Mai.one. — Massive pyrite^ magnetite. GENESEE CO. — Acid springs containing sulphuric acid. GREENE CO.— Catskill.— ttrfc/te. Diamond Hill. — Quartz crystals. HERKIMER CO. — Fairfield. — Quartz crystals, fetid barite. Little Falls. — Quartz crystals' barite, calcite, anthracite, pearl spar, fimoky guarta, one mile south of Little Falls, calcite. brown spar, feldspar. Middlevil: K. — Quartz crystals ! calcite, brown and pearl spar, anthracite. Newport. — Quartz crystals. Salisbuuy. — Quartz ci-ystals ! blende, galenite, pyrite, chalcopyrite. Stark. — Fibrous celestite, gypsum. HAMILTON CO.— Long Lake.— Blue calcite. JEFI'ERSON CO.— Adams.— Fluor, calc tufa, barite. Alexandria. — On the S.E. bank of Muscolouge Lake, f^xxorite, pldogopite, chalcopyrite, apatite; on High Island, in the St. Lawrence River, feldspar, tourmaline, hornblende, ortho- clase, celestite. Antwerp. — Stirling iron mine, hematite, chakodite, siderite, millerite, red hematite, crys taliized quartz, yelloic aragonite, niccoliferous pyrite, quartz crystals, pyrite ; at Oxbow, cal- cite! porous coralloidal heavy spar; near Vrooman's Icke, calcite/ \esuYianite, phlogopite / pyroxene, sjJicne, fluorite, pyrite, chalcopyrite ; alno feldspar, bog-iron ore, scapolite (farm ol David Eggleson), serpentine, tourmaline (yellow, rare). Brownsville. — Celestite in slender crystals, calcite (four miles from Watertown). Natural Bridge. — Feldspar, giescckite ! steatite p!seudomorp?u)us after pyroxene, apatite. New Connkcttcut. — I'vphcne, broira p/ilogo2)ite. Omar. — Beryl, feldspar, hematite. PniLADELPiiiA. — Garnds on Indian river, in the village. Pamelia. — .Ujaric mineral, calc tufa. PlEitiiKi'oNT. — Tourmaline, sphene, scapolite, hornblende. Pillar Point. — Nassice barite (exhsLUsted). Tnr,nES\.— Fluorite, calcite, hematite, hornblende, quartz crystals, serpentine (associated with hematite), celestite, stroutianite ; the Muscolonge Lake locality of tiuor is exhausted. Watertown. — Tremolite, agaric mineral, calc tuta, celestite. WiLNA.— One mile north of Natural Bridge, calcite. LEWIS CO. — Diana (localities mostly near junction of ciystalline and sedimentary rocks, and within two miles of Natural Bridge). — JScapolite / woUastouite, green coccolite, feldspar, tremolite, pyroxene I sphene.! ! mica, quartz crystals, drusy quartz, cryst. pyrite, pyrrhotite, blue calcite, serpentine, rensselaerite, zircon, graphite, chlorite, hematite, bog-iron ore, iron Band, apatite. Greig. — Magnetite, pyrite. Lowville. — Calcite. tiuorite, pyrite, galenito, blende, calc tufa. Martinsiuirgii. — Wad, galenite, etc., but mine not now opened, calcite. Watson, Bremen. — Bog-iron ore. MONROE CO.— Rocuester. — Pearl spar, calcite, snowy gypsum, fluor, celestite, galenite, blende, barite, hornstone. MONTGOMERY CO.— Canajoharie. —Anthracite. Palatine. — Quartz crystals, drusy quartz, anthracite, hornstone, agate, garnet. Root. — Draxy quartz, blende, barite, stalactite, stalagmite, galenite. pyrite. NEW YORK CO.— Corlear's Hook.— Apatite, brown and yellow feldspar, sphene. KiNGSBRiDGE. — Tremolite, pyroxene, mica, tourmaline, pyrites, rutile, dolomite. Harlk.m. — Epidor^e, apophyllite, stUbite, tourmaline, vivianite. lamellar feldspar, mica. New York. — Serpentine, amianthus, actinolite, pyroxene, hydrous anthophyllite, garnet, itaurolite, molybdenite, graphite, chlorite, jasper, necronite, feldspar. In the excavations foi the 4th Avenue tunnel, iy75, harmotome, stilbite, chabazite, heulandite, eto. AMERICAN LOCALITIES. 483 NIAGARA CO. — Le wiston. — Epsomite. LocKPOuT. — Celestite, calcite, selenite, anhydnte, jluorite, dolomite, blende. NiAGAUA Falls.- -6'afciie, fluorite, blende, dolomite. ONEIDA CO. — BooNViLLE. — Caldte. woUastonite, coccoUte. Clinton. — Blende, Icnticidiir argillaceous iroaore; in rocks of the Clinton Group, stronti anite, celesbite, the former covering the latter. ONONDAGA CO. — Camcllus. — Selenite 00.6. fibrous gypsum. Cold Spring— Axinite. Manlius. — GypKum and fluor. Syracuse. — Serpentine, celestite, selenite, barite. ORANGE CO. — Cornwali,. — Zircon, chondrodite, hornblende, spinel, massive feldspar, fibrous epidote, hud-e»tus ; near E. Taylor's mill, chromite in octahedral crystals, dewcylite, radiated magnesite, aragonite, staurotile. garnet, asbe.stus, epidote; zoi.iite on hornblende at West Chester water-works (not acces.«ible at present*. New Garden. — At Nivrn's limestone quarry, brown tourmaline, necronite, scapolite, apa- tite, bro\vn and green mica, rutile, a ragonitt, Jibr. — In the railroad tunnel at Piicenixville, dolomite! sometimes coated with pyrite, quartz crystals, yellow blende, brookite, C(dcite in hexagonal crystals enclosing pyrite ; at the WiiEATLEY, Brookdale, and Chester County lead mines, one and a half mile S. QiVh.(£,vi\y.v\\{%,pyiomorphite! ceruaaite ! galenite, angledte! ! quartz crystals, chalcopy- rite, barite, fluorite (white), stokite, wulfenite! calamine, vccnadiuite, blende! mimetite! descloizite, guthite, chrysocolla, native copper, malachite, azurite, liTnonite, calcite, sulj)hury pyrite, melaconite, pseudomalachite, gersdorffite, chalcocite ? covellite. Tiiornbury. — On Jos. H. Brinton's farm, muncoDite containing acicular crystals of tour- maline, rutile, titaniferous iron. Tredyffkin— /-*^;'i.— Andalusite, tourmaline, beryl, titanic iron, garnet; on Fell's Laurel Hill, beryl, garnet; near Beattie's mill, staurolite, apatite; near Lewis's paper-mill, tourmaline, mica. Thornbury, — Amethyst. HUNTINGDON CO. — Near Frankstown. — In the bed of a stream and on the side of a hill, fibrous celestite (abundant), quartz crystals. LANCASTER CO. — Drumore Township.— Qaartz crystals. Fulton. — At Wood's chrome mine, noar the village of Texas, brucitef ! zaratite (emerald nickel), pennite ! ripidolite! kdmrnereritc ! b(dtimorite, chromic iron, williamsite, chrysolite! marmolite, picrolite, hydromagnesite, dolomite, magnesite, aragonite, calcite, serpentine, hematite, menaccanite, genthite, chrome-garnet, bronzite, milleritc ; at Low's mine, hydro- magnesite, brucite (lanca.sterite), picrolite, magnesite, williamsite, chromic iron, ta'c, zaratite, baltimorite, serpentine, hematite ; on M. Boice's farm, one mile N.W. of the village, pyrite in cubes and various modifications, antliophyllite ; near Rock Springs, chidcedony. camelian, moss agate, green tourmaline in talc, titanic iron, chromite, octahedrnji/i««?/irte (pseud, of dolomite), aurichalcite. AMERICAN LOCALITIES. 489 LEBANON CO.— Cornwall. — Magnetite, pyrite (cobaltiferous), chalcopyrite, native cop- per, azurite, malachite, chrysocolla, cujirite (hydrocuprite), allophane, brochantite, aerpentine, quartz pseudomorphs ; galenite (with octahedral cleavage), tiuorite, covellite, heinajite (mi caceous), opal, asbestus. LEHIGH CO — FRiEDENSviLLE.^At the zinc mines, Mlmnine, smitlisonite, hydrozinciie, massive blende, greenockite, quartz, allophane, zinciferous clay, mountain leather, aragonite, eauconite ; near Allentown, magnetite, pipe-iron ore ; near Bethlehem, on S. Mountain, alianite, with zircon and altered sphene in a single isolated mass of syenite, magnetite, mar- tite, black spinel, tourmaline, chaJcocite. JUFFLIN CO.— Strontianite. MONROE CO. — In Ciiekry Valley. — Galcite, chalcedony, quartz; in Poconac Valley, near Judge Mervine's, cryst. quartz. MONTGOMERY CO. — Conshohocken. — Fibrous tourmaline, menaccanite, aventurine quartz, pbyllite ; in the quarry of Geo. Bullock, calcite in hexagonal prisms, aragonite. Lower Providence. — At the Perkiomen lead and copper mines, near the village of ShannonvUle, azurite, blende, galenite, pyromorphite, cerassite, wulfenite, anglesite, barite, calamine, chalcopyrite, malachite, chrysocolla, brown spar, cuprite, covellite (rare), mela- conite, libethenite, pseudomalachite. White Marsh. — At D. 0. Hitner's iron mine, five and a half miles from Spring Mills, limonite in geodes and stalactites, gutldte, pyrolusite, wad, lepidocrocite ; at Edge Hill Street, North Pennsylvania Railroad, titanic iron, braunite, pyrolusite; oie mde S.W. of Hitner'a iron mine, Uinonite, velvety, stalactitic, and fibrous, fibres three inches long, turgite, gothitc, pyrolusite, velvet manganese, wad ; near Marble Hall, at Hitner's marble quarry, white mar- ble, granular barite, resembling marble ; at Spring Mills, limonite, jiyrolusite, gothite ; at Flat Rock Tunnel, opposite Manayxink, utilbite, heulandite, chabasite, ilvaite, beryl, feldspar, mica. Lafayette, at the Soapstone quarries. — Talc, jefferisite, garnet, albite, serpentine, zoisite, etaurolite, chalcopyrite ; at Rose's Serpentine quarry, opposite Lafayette, enstatite, serpen- tine. NORTHUMBERLAND CO.— Opposite Selim's Grove.— Calamine. NORTHAMPTON CO.— Bushkill Township.— Crystal Spring on Blue Mountain, quam crystals. Near Easton. — Zircon! (exhausted), nephrite, coccolite, treraolite, pyroxene, sahlite, limonite, magnetite, purple calcite. Williams Township. — Pyrolusite in geodes in limonite beds, gothite (lepidocrocite) at Glendon. PHILADELPHIA CO. — Frankpord. — Titanite in gneiss, apophyllite ; on the Philadelphia, Trenton and Connecting Railroad, basanite ; at the quai-ries on Frankford Creek, stilbite. molybdenite, hornblende ; on the Connecting Railroad, wad, earthy cobalt ; at Chestnut HUl, magnetite, green mica, chalcopyrite, fluorite. Fair.mocnt Water Works. — In the quarxies opposite Fairmount. autiinite ! torbernitt crystals i^ffeldxpar, beryl, pseudomorphs after beryl, tourmaline, albite, wad, menaccanite. GouGAs' and Crease's Lane. — Tourmaline, cyanite, staurolite, hornstone. Near Germantown.— ^toc^• tourmaline, laumontite, apatite; York Road, tourmaline, beryl. Hestonville. — Alunogen, iron alum, orthoclase. Heft's Mill. — Alunogen, tourmaline, cyanite, titanite. Manayunk. — At the soapstone quarries above Manayunk, talc, steatite, chlorite, vermicu- lite. antliophyllite, staurolite, dolomite, apatite, asbestus, brown spar, epsomite. Mf,.\gargee's Paper-mill. — Staurolite, titanic iron, hyalite, apatite, green mica, iron gar- nets in great abundance. McKinney's Quarry, on Rittenhouse Lane. — Feldspar, apatite, stilbite, natrolite, Iteulan- dite. epidote, hornblende, erubescite, malachite. Schuylkill Falls. — Chabazite, titanite, fluorite, epidote, muscovite, tourmaline, pro- chlorite. SCHUYLKILL CO.— Tamaqua, near Pottsville, in coal mines. — Kaolinite, YORK CO. — Bornite, rutile in slender prisms in granular quartz, calcite. 490 APPENDIX. DELAWARE. NEWCASTLE CO. — Brau dywine Springs. — Buc7iolgite, fibroUte nhnndant, sahlite, pyrox ene ; Brandy wine Hundred, muscovite, enclosing reticulated magnetite. Dixon's Fkldspar Quarries, six miles N. W. of Wilmington (these quarries have been worked for the manufacture of porcelain). — Adtdaria, albite, oligodase, be7'yl, apatite, cinna- mon-stone! ! (both granular like that from Ceylon, and crystallized, rare), inagnesite, serpen- tine, asbestus. black tourmaline ! (rare), indicolite! (rare), sphene in pyroxene, cyanite. Ddpont's Po^vder Mills. — •' Hypersthene." Eastburx's Limestone Quarries, near the Pennsylvania line. — Tremolite, bromite. QuARRYViLLE. — Garnet, sp'idumene, fibrolite. Near Newark, on the railroad. — Sphserosiderite on drusy quartz, jasper (ferruginous opal), cry.st. spathic iron in the cavities of cellular quartz. Way's Quarry, two miles south of Centreville. — Feldspar in fine cleavage masses, apatite, mica, dewn/lite. grannlar quartz. Wilmington. — In Christiana quarries, mdalloidal di^tone ! ! smoky quartz! aventurine fddspaTy ame thyst, albite^ fluorite, hematite, anhydrite (rare), columbite. CANADA. CANADA EAST. Abercrombie. — Labradorite. Bay St. PAVh.—3feniiaecainte/ apatite, allanite, rutile (or brookite ?) Aubert. — Gold, iridosmine, platinum. 'BohTO'S. — Chromite, magnesite, serpentine, picrolite, steatite, bitter spar, wad. BocrciiERVlLi,E. — Augite in trap. BuoMK. — Magnetite, chalcopyrite, sphene, menaccanite, phyllite, sodalite, cancruiite, galenite, chloritoid. CiiAMiJi.Y. — Analcite, chabazite and calcite in trachyte, menaccanite. Chateau Richer. — Lnbradorite, hyperstheue, andesite. Daillebdut. — Blue spinel with clintonite. Grenvii.le. — Wollastonite, sphene, vesuvianite, calcite, pyroxene, steatite (rensselaerite), garnet (cinnamon-stone), zircon, graphite, sea polite. Ham.— Chromite in serpentine, diallage, antimony ! senarmontite ! kermesite, valentinite, etibnite. Inverness. — Vnrigatcd caliper. Lake St. Francis. — Aiuldusite in mica slate. Landsdown. — Biirite. Leeds. — Dolomite, chalcopyrite, gold, chloritoid. MiLLE Isles. — Labrndoritt ! menaccanite, hypersthene, andesite, tircon. Montreal, — Otdcite, augite, sphene in trap, chrysolite, natrolite, dawsonite. MoRlN. — S])he.nc, apatite, labradorite. Orford. — White garnet, chrome garnet, millerite, serpentine. Ottaw.v. — Pyroxene. PoLTON. — Chromite, steatite, serpentine, amianthus. RoUGEMONT. — Augite in trap. Sherbrook. — At Suffield mine, albite ! native silver, argentite, chalcopyrite, blende. St. Ar.mand. — Micaceous iron ore with quartz, epidote. St. Fran(,ois Beauce. — Gold, platinum, iridosmine, menaccanite, magnetite, serpentine, chromite, soapstone, barite. St. Jekom,;. — Sphene, apatite, chandrodite, phlogopite, tourmaline, zircon, molybdenite, pyrrhotite. St. Norijert. — Amethyst in greenstone. Stukeley. — Serpentine, verd-antique ! schiller spar. Sutton. — Magnetite in fine crystals, hematite, rutile, dolomite, magnesite, chromiferoui talc, bitter spar, steatite. Upton. — Chalcopyrite, malachite, calcite. Vaudreuil. — Limonite, vivianite. YA.MASICA. — Sphene in trap. CANADA WEST. Arnprior. — Calcite. Balsam Lake. — Molybdenite, scapolite, quartz, pyroxene, pyrlte. Brantford. — Sulphuric acid spring (42 parts of pure sulphuric acid in 1000). Bathurst. — Barite, black tourmaline, perthite (orthoclase), pcmimie (albite), bytoi/DntUy pyroxene, wilsonite, scapolite, apatite, titanit*. 500 APPENDIX. Brockville. — Pyrite. Brome. — Magnetite. Bruce Mines. — Calcite, dolomite, quartz, chalcopyrite. Burgess. — Pi/roxene, albite, mica^ mpphire^ sphene, chalcopyrite, apatite, black apintlt Bpodumene du a boulder), serpentine, biotite. Bytown. — Calcite, bytownite, chondrodite, spinel. Cape Ipperwash. Lake Huron. — Oxalite in shales. Clarendon. — Vesuvianite. DALnousiE. — Hornblende, dolomite. Drummund. — Labradorite. Elizabethtown. — PyrrJiotite, pyrite, calcite, magnetite, talc, phlogopite, siderite, apa- tite, cacoxenite. Elmsey. — Pyroxene, sphene, feldspar, tourmaline, apatite, biotite, zircon, red spinel, chondrodite. FiTZROY. — Amber, brown tourmnline, in quartz. GffiTiNEAU River, Blasdell's Mills.— Calcite, apatite, tourmaline, hornblende, pyroxents. Grand Calumet Island. — Apatite, pWogofite ! pyroxene ! sphene, vesuvianite ! ! serpen* tine, tremolite, scapolite, brown and black tourmaline ! pyrite, loganite. High Falls op the Madawaska. — Pyroxene! hornblende. Hull. — Magnetite, garnet, graphite. HUNTERSTOWN. — ScapoHte, S2)hene, vesuvianite, garnet, broicn tourmaline/ Huntington. — Calcite ! Inniskillen. — Petroleum. Kingston. — Celestite. Lac des Chats, Island Portage. — Brown tourmaline! pyrite, calcite, quarts. L.\NARK. — Raphilite (hornblende), serpentine, asbestus. Landstown. — Barite! vein 27 in. wide, and fine crystals. Madoc. — Magnetite. Mamora. — ]Magnetite, chalcolite, garnet, epsomite, specular iron. Maim ansr. — Pitchblende (coracitej. McXab. — Hematite, barite. JMiciiipicoten Island, Lake Superior. — Domeykite, niccolite, genthite, Newborough. — Chondrodite, graphite. Packenham.— Hornblende. Perth. — Apatite in large beds, phlogopite. South Crosby. —Chondrodite in lime.stone, magnetite. St. Adkle. — Chondrodite in limestone. St. Ignace Island. — Calcite, native copper. Sydenham. — Celestite. Terrace Cove, Lake Superior. — Molybdenite. Wallace Mine, Lake Huron. — Hematite, nickel ore, nickel vitriol. NEAV BRUNSWICK* Albert Co. — Hopewell, gypsum ; Albert mines, coal (albertite) ; Shepody Mountain, alunite in clay, calcite, iron pyrites, mangavite, psilomelane, pyrohisite. Carleton Co. — Woodstock, chalcopyrite, hematite, limonite, wad. Charlotte Co. — Campobello, at Welchpool, blende, chalcopyrite, bornite, galenite, pyrite; at head of Harbor de Lute, galenite ; Deer Island, on west side, calcite, magnetite, quart.z crystals; Digdignash River on west side of entrance, calcite! (in conglomerate), chalcedony ; at Rolling Dam, graphite ; Grandmanan, between Northern Head and Dark Harbor, agate, amethyst, apnpJiyUite, ca'cite. hematite, heulandite, jasper, magnetite, natro- lite, stilbite ; at Whale Cove, calcite ! heulandite, laumontite. stilbite, semi-opal! Wagagua- davic River, at entrance, azurite, clialcopyrite in veins, malachite. Glodcestek Co. — Tete-a-Gouche River, eight miles from Bathurst, chalcopyrite (mined), oxide of mangaue-ie! ! formerly mined. Klngs Co. - -Sussex, near Gloat's mills, on road to Belleisle, argentiferous galenite ; one mile north of Baxter's Inn, specular iron in crystals, limonite; on Capt. McCready's farm, ielenite! ! Restigouciie Co. — Belledune Point, calcite! serpentine, verd-antdgue ; Dalhousie, agate, oamelian. * For a more complete list of localities in New Branswick, Nova Scotia, and Newfoand land, see catalogue by O. C. Marsh, Am. J. Sci., II. xxxv. 210, 1863. AMERICAN LOCALITIES. 501 Saikt John Co, — Black River, on coast, calcite, chlorite, chal(x->p7rite, hematite ! Brandj Brook, epidote, hornblende, quartz crystals ; Carleton, near Falls, calcite ; Chance Harbor, ca/ci7e in quartz veins, chlorite in argillaceous and talcose slate; Little Dipper Harbor, on west side, in greenstone, amethyst, barite, quartz crystals ; Moosepath, feldspar, hornblende, muscovite, black tourmaline ; Musquash, on east side harbor, copperas, graphite, pyrite ; at Shannon's, chrysolite, serpentine; cast side of Musquash, quartz crystals! ; Portland, a< the Falls, graphite ; at Fort Howe Hill, calcite, graphite ; Crow's Nest, asbestus, chrysolite, magnetite, serpentine, steatite; Lily Lake, white augite? chrysolite, graphite, serpentine steatite, talc; How's Road, two miles out, epidote (in syenite), steatite in limestone, tremo lite ; Drary's Cove, graphite, pyrite, pyrallolite ? indurated talc ; Quaco, at Lighthouse Point, large bed oxyd of manganese ; Sheldon's Point, actinolite, asbestus, calcite, ejddote, mala- chite, specular iron ; Cape Spenser, asbestus, calcite, chlorite, specular iron (in crystals) ; Westbeach, at east end, on Evans' farm, chlorite, talc, quartz crystals ; half a mile west, chlorite, chalcopyrite, raagnesite (vein), magnetite ; Point Wolf and Salmon River, asbestus, chlorite, chrysocolla, chalcopyrite, bomite, pyrile. Victoria Co. — Tabique River, agate, cariielian, jasper; at mouth, south side, galenite ; at mouth of Wapskanegan, gypsum, salt spring ; three miles above, stalactites (abundant) ; Quisabis River, blue phosphate of iron, in clay. Westmorei.and Co. — BeUevue, pyrite; Dorcester, on Taylor's farm, cannel coal; clay ironstone ; on Ayres's farm, asphaltum, petroleum spring; Grandlance, apatite, selenite (in large crystals) ; Memramcook, coal (albertite) ; Shediac, four miles up Scadoue River, coaL York Co. — Near Fredericton, stibnite, jamesonite, berthierite ; Pokiock River, stibmte, tin pyrites f in granite (rare). NOVA SCOTIA. Annapolis Go.— GhvAe's Co\e^ npoyhyllite, uatroWte^ Gates' Mountain, analcite, magne- tite, mesoHte! natrolite, stilbite ; Martial's Cove, ana'lcite! chabazite, Jieulandite ; Moose River, beds of mag-netite ; Nictau River, at the Falls, bed of hematite ; Paradise River, black tourmalin'^, smoky quartz !! ; Port George, fari'jelite, laumontite, mesolite, stilbite; east of Poit George, on coast, apophyllite containing gyrolite ; Peter's Point, west side of Stonock's Brook, apophy'iite ! calcite, heulandite, lawtwntite ! (abundant), native copper, stilbite; St. Croix Cove, chabazite, heulandite. CoLCiiKSTEit Co. — Five Islands, East River, barite! calcite, dolomite (ankerite), hematite, chalcopyrite ; Indian Point, malachite, magnetite, red copper, tetrahedrite ; Pinnacle Islands, analcite, calcite, cliabazite! natrolite, siliceous sinter; Londonderry, on branch of Great Village River, barite, ankerite, hematite, limonite, magnetite; Cook's Brook, ankerite, hema- tite ; Martin's Brook, hematite, limonite ; at Folly River, below Falls, ankerite, pyrite ; on high land, east of river, ankerite, hematite, limonite ; on Archibald's land, ankerite, barite^ hematite ; Salmon River, south branch of, chalcopyrite, hematite ; Shubenacadie River, anhydrite, calcite, barite, hematite, oxide of manganese ; at the Canal, pyrite ; Stewiacke River, barite (in limestone). CuMBKKi.AND Co. — Cape Chiegnecto, barite; Cape D'Or, analcite, aqiophyllite ! ! chaba- eite, faroelite, laumontite, mesolite, malachite, natrolite, native copper, obsidian, red copper (rare), vivianite (rare); Horseshoe Cove, east side of Cape D'Or, analcite, calcite, stilbite; Isle Haute, south side, analcite, apojihyllite ! ! calcite, heulandite! ! natrolite, mesolite, stil- bite ! Joggins, coal, hematite, limonite ; malachite and tetrahedrite at Seaman's Brook ; Partridge Island, analcite, apophyllite! (rare), amethyst! agate, apatite (rare), calcite! ! chabazite (acadialite), chalcedony, cat's-eye (rare), gypsum, hematite, heulandite ! magne- tite, stilbite! ! ; Swan's Creek, west side, near the Point, calcite, gypsum, heulandite, pyrite ; east side, at Wasson's Bluff and vicinity, analcite! ! apophyllite! (rare), calcite, cha.bazite ! ! (acadialite), gypsum, heulandite ! ! natrolite! siliceous sinter; Two Islands, moss agate, analcite, calcite, chabazite, heulandite ; McKay's Head, analcite, calcite, heulandite, siliceoiis sinter ! DiGBY Co. — Brier Island, native copper, in trap; Digby Neck, Sandy Cove and vicinity, agate, amethyst, calcite, chabazite, hematite ! laumontite (abundant), magnetite, stilbite, quartz crystals; Gulliver's Hole, magnetite, stilbite! ; Mink Cove, amethyst, chabazite I quartz crystals; Nichols Mountain, south side, amethyst, magnetite! ; Williams Brook, Dr;ar source, chabazite (green), heulandite, stilbite, quartz crystal. GuYSBORo' Co. — Cape Canseau, andahisite. Halifax Co. — Gay's river, galenite in limestone ; southwest of Halifax, garnet, staurolite, tourmaline: Tangier, gold! in quartz veins in clay slate, associated with auriferous pyrites, galenite, hematite, mispickel, and niaguetite ; gold has also been found in the same forma- tion, at Country Harbor, Fort Clarence, Isaac's Harbor, Indian Harbor, Laidlow'a farm, Lawrencetown, Sherbrooke, Salmon River, Wine Cove, and other places. 502 APPENDIX. Hants Co. — Cheverie, oxide of manganese (in limestone) ; Petite River, gypsum, oxiile of manganese ; Windsor, calcite, cryptomorphite (boronatrocalclte) , howlite, glauber dalt. The last three minerals are found in beds of gypsum. Kings Co. — Black Rock, centrallassite, cerinite ; cyanolite ; a few miles east of Black Rock, prehnite '{ stilbite ! ; Cape Blomidon, on the coast between the cape and Cape Split, the following minerals occur in many places (some of the best localities are nearly opposite Cape Sharp): aualcite! ! agate, amethyst! ajwphyllite ! calcite, chalcedony, chabazite, gme- Unite (ledererite), hematite, heidandite ! laumontite, magnetite, malachite, mexolite^ native copper (rare), natrolite ! psiloraelane, stilbite ! thomsonite. faroelite, quartz; North Moun- tains, amethyst, bloodstone (rare), ferrvginons quartz, memlite (in soil) ; Long Point, five miles west of Black 'Rock. ?ieulandite, laumontite! ! stilbite! ! ; Morden, apoj^hyllite, mor- denite ; Scot's Bay, agate, amethyst, chalcedony, mesolite, natrolite ; Woodworth's Cove, a few miles west of Scot's Bay, agate ! chalcedony ! jasjter. LuNJONBURG Co. — Chester, Gold River, gold in quartz, pyrite, mispickel ; Cape la Have, pyrite ; The " Ovens," gold, pyrite, arsenopyrite ; Petite River, gold in slate. PiCTOU Co. — Pictou, jet, oxide of manganese, limonite ; at Roder's Hill, six miles west of Pictou, barite ; on Carribou River, gray copper and malachite in lignite ; at Albion mines, coal, limonite ; East River, limonite. Queens Co. — Westfield, gold in quartz, pyrite, arsenopyrite ; Five Rivers, near Big Fall, gold in quartz, pyrite, arsenopyrite, limonite. Richmond Co. — West of Plaister Cove, barite and calcite in sandstone ; nearer the Cove, caicite, Jluo7-ite (blue), siderite. Shelburne Co. — Shelbume, near mouth of harbor, garnets (in gneiss); near the town, rose quartz ; at Jordan and Sable River, stuuroHte (abundant), schiller spar. Sydney Co. — Hills east of Lochaber Lake, pyrite, chalcopyrite, sideride, hematite ; Mor- ristown, epidote in trap, gypsum. Yarmouth Co. — Cream Pot, above Cranberry HiU, gold in quartz, pyrite; Cat Rock, Fouchu Point, asbestus, calcite. NEWFOUNDLAND. Antony's Island. — Pyrite. Catalina Harbor. — On the shore, pyrite! Chalky Hill. — FeldsjMir. Copper Tsl.\nd, one of the Wadham group. — Clialcopyrite. Conception Bay. — On the shore south of Brigus, bornite and gray copper in trap. Bay of Islands. — Southern shore, pyiite in slate. La"w:n. — Galenite, cerargynte, proustite, argentite. Placentia Bay. — At La Manche, two miles eastward of Little Southern Harbor, g rlenite ' ; on the opposite side of the isthmus from Placentia Bay, barite, in a large vein, occasion! Jj B(!Companied by chalcopyrite. Shoal Bay. — South of St. John's, chalcopyrite. Trinity Bay. — Western extremity, barite. Habbob Great St. Lawrence. — West side, fluo. lie, galenite. APPENDIX D. SUPPLEMENTARY CATALOGUE OF AMERICAN LOCALITIES OF MINERALS. MAINE. Norway. — Tripbylite (lithiophilite\ clirysobcryl, eooteite. Paris. — Colunibite, mica, triphylite. Parsonfield, — Labradorit e, crystallized. Peru. — Triphvlite (erystallizi'd), columbite. beryl, spodumene. Stoneuam. — Triplite, columbite, topaz, curved mica. NEW HAMPSHIRE. Baetlett. — At the iron mine, danalite. MASSACHUSETTS. Deerfield. — In diabase, datolite, stilbite, chabazite, prehnite, heulandite, natrolite, analcit^, calcite, llnorite, albite, c])idote, axinitc, tourmaline, diabantite, saponite, chloro- phfpite, kaolin, pyrite. malachite, llmonite, wad. RocKPOBT. — Fcrgusonito, __ CONNECTICUT. Branchtille.— In a large vein of pegmatite in gneiss, mica (curved concentric), microc-line, albite (also crystallized), (piartz (inclosing liquid C0..\ spodumene and various alteration produces (eucryptite, cvmatolite, killinite, etc.), columbite, apatite (also manganapatite), amblygonite, lithiophilite, eosphorite, Iriploidite, dickinsonite, reddingite, fairfieldite, fiUowite, rhodoelirosite, uraninite (crystals^ cyrolite, microlite, uranium phosphates, chabazite, stilbite, heulandite and other species. Litchfield. — Staurolite in mica schist. New Haven. — At Mill Rock, contact surface of trap and sandstone, garnet (topazolite); at East Rock, on columnar surfaces of trap, garnet (mclanite), magnetite, pyroxene, apatite, calcite. Portland. — At Pelton's feldspar quai*ry, monazite. NEW YORK. CLINTON CO. — Plattsburg, nugget of platinum in drift. ESSEX CO. — Port Henry, black tourmaline enclosing orthoclase; Champlain iron region, uranothnrite. ST. LAWRENCE CO.-DeKalb, white tourmaline. PiCTAiRX. — Titanite. Russell.— In veins in a granitic rock, danburite with pyroxene, titanite, black mica. NEW JERSEY. Bergen. — Hayesine. Franklin Furnace and Sterling. — Chalcophanite, hetserolite, pyrochroite. 503 50i APPENDIX. PENNSYLVANIA. BEDFORD CO.— Bridgeport, barite. BEUKS CO. — Jones's mine, aurichalcite, melaconite, byssolite. BUCKS CO. — l^HEXixviLLE, ankeiite. Bridgewater Station. — Titanile. CHESTER CO.— Yellow Springs, allanite. DELAWARE CO.— Waterville, near Chester, and Uplar.d, chabazite. Mineral Hill, columbite. Leiperville. garnet, zoisite, heulandite, leidyite. FRANKLIN CO. — Lancaster Station, barite. HlNTiNGTON CO.— Broad Top Mointain, barite. LEHIGH CO. — Shimerville, corundum. LUZERNE CO. — Scranton, under a i:)eat-bed, phytocoUite (dopplerite). Drifton, pvrophvllite. MIFFLIN CO.— Strontianite. MONTGOMERY CO. -Upper Salford mine, azmite. NORTHAMPTON CO.— Bethlehem, axinite. PHILADELPHIA CO.— Germantown. fahlunite. SCHUYLKILL CO., near Mahanoy City, pyrophyllite, alunogen, copiapite, in eoa! mines. DELAWARE. Dixon's Quarry. — Columbite. Newark. — Quartz crystals, doubly terminated, loose in soil. VIRGINIA. AMELIA CO. — From a granite vein (mica mine) in gneiss near Amelia Court House, mica in large sheets, quariz, orthoclase, microlite. monazite, columbite, orthite, heivite with topazolite, beryl, fluorite, amethyst, apatite (rare). AMHERST CO. — From a feldspar vein in a gneissoid rock on the northwest slope of Little Friar Mt., allanite, sipylite. magnetite, zircon. ROCKBRIDGE CO. — Underlying limonite, dufrenite in an irregular bed ten inches deep, strengite in cavities in dufrenite. WYTHE CO.— Austin mine, aragonite (7 p. c. PbCOa). NORTH CAROLINA.* Alexander Co. — Near Stony Point, in narrow veins or pockets in a gneissoid rock (in part also loose in overlying soil"), spodumene (hiddenite), beryl (emerald), rutiie, monazite, allanite, quartz. At White Plains, quartz ciystals, spodumene (hiddenite), beryl, rutiie, scorodite, columbite, tourmaline. At Milholland's mill, rutiie, monazite, muscovite, quartz. Burke Co. — In the auriferous gravels at Brindletown, octahedrite (transparent), brookite, zircon, fergusonite, monazite, xenotime (compounded with zircon\ garnet, tourmaline, magnetite and other species. Mitchell Co. — At the mica mines, muscovite in large quantities, ortlioelasc. albite, samarskite. columbite, hatchettolite, rogersite, fergusonite, monazite, uraninite, gummite, phosphuranylite, uranotile. allanite, beryl, zoisite. garnet, mcnaccanite. Yancey Co. — At the Ray mica mine, muscovite, tantalite (columbite), monazite, beryl, garnet, zircon, rutiie, etc. At Hampton's, chromite, epidote, enstatite, tr»^raolite, chrysolite, serpentine, talc, niagnesite, etc. ALABAMA. COOSA CO.— Cassiterite, tantalite. * For a complete list of the minerals and mineral localities of North Carolina, see Geology of North Carolina, vol. II., chap. I.. Mineralogy by F. A. Genth and W. C. Kerr, with notes by W. E. Hidden; 122 pp., Svo, Raleigh, 1881. " AMERICAN LOCALITIES. MICHIGAN. 505 Negaunee. — Manganite, gothite, liematite, barite, kaoUnite. Gkand Marais. — Thomsonite (lintonite). * MISSOURI.* ADAIR CO.— Gothite with calcite in concretionary masses of clay iron-stone. BAliTON CO.— McCarrow's coal bank, pickeringite, as a white efflorescence on sandy shales of coal measure.-. BENTON CO — Limonite. BOLLINGER CO. — Limonite, bog manganese, psilomelane. CALLAWAY CO.— Hematite, clay iron ore. CHARITON CO — Selenite. COLE CO —Barite. At the Eureka mines, galenite, smithsonite. COOPER CO. —Collins mine, malachite, azurite, chalcopyritL-, smithsonite, galenite sphalerite, limonite. CRAWFORD CO.— Scotia iron banks, hematite, quartz, jasper, amethyst, gothite, malaeliite. DADE CO.— Smithsonite. DENT CO.— Simmon's Mountain, hematite. FRANKLIN CO. — Cove mines, galenite, cerussite, anglesite, barite. Mino-a-Burton, galenite, cerussite, anglesite. Moselle, limonite. Mount Hope mine, galenite, sphalerite, calamine, smithsonite. Stanton Copper mines, native copper, chalcotrichite, malachite, azurite, chalcopyrite. Virginia mines, galenite, anglesite, cerussite, minium. IRON CO. — Pilot Knob, hematite, serpentine, magnetite, quartz, manganese ore. JASPER CO.— Joplin mines, galenite, sphalerite, pyrite, marcasite, cerussite, bitumen. Oroxogo. — Galenite, sphalerite, cerussite, smithsonite, anglesite. Webb City. — Galenite, sphalerite. JEFFERSON CO.— Palmer mines, galenite, cerussite, plumbogummite. Valle mines, galenite, cerussite, anglesite, calamine, smithsonite, hydrozincite, mala- chite, azurite. MADISON CO. — Enistein silver mine, galenite, sphalerite, wolframite, pyrite, quarts, muscovite, actinolite, fluorite. MiNE-LA-MoTTE. — Galenite, linna^ite (siegenite), cerussite, anglesite, pyrrhotite, earthy cobalt, bog manganese, plumbogummite, chalcopyrite, annabergite. In granites, porphyries, etc., quartz, agate, hornblende, asbestos, serpentine, chlorite, epidote, feldspar. MONITEAU CO —Sampson's coal mine, galenite and sphalerite in cannel coal. MORGAN CO.— Buffalo mines, galenite. Humes Hill, barite. NEWTON CO.— Granby mines, galenite, cerussite, pyromorphite, calamine, greeno- chite. sphalerite, smithsonite, hydrozincite, buratite, dolomite, calcite. PHELPS CO — Hematite, siderite, limonite, ankerite. ST. FRANCOIS CO. — Iron mountain, hematite, apatite, tungstite, wolframite, magne- tite, menaccanite. ST. GENEVIEVE CO. — St. Genevieve copper mines, chalcopyrite, cuprite, malachite, azurite, covellite, chalcocite, bornite, melaeonite, chalcanthite. ST. LOUIS CO.— St. Louis. — In cavities in limestone, miUerite, dolomite, calcite, fluorite, anhydite, gypsum, strontianite. SALINE CO. — Halite in incrustations. WAYNE CO.— Limonite. KANSAS. BROWN CO.— Celestite. ARKANSAS. Sevier Co. — Stibnite, stibieonite, bindheimite, jamesonite. Hot Springs Co. — Rutile in eightling;, variscite. *See Notes on the Mineralogy of Missouri, by Alexander V. Leonhard, St. Louis, 1883. 506 APPENDIX. COLORADO. Boulder Co — Magnolia district (especially the Keystone, Mountain Lion and Smuggle* mines), native tellurium, coloradoite, calaverite, tellurite, magnolite, ferrotellurite, sylvaiiite. Chaffee Co. — Arrow mine, jarosita with turgite. . Custer Co. — Silver cliff, niccolite. El Paso County. — Ne.ir I'ike's Peak, arfvedsf mite, astrophy lite zircon; fiderophyllite, topaz, phenacite, cryolite, tS.onisenoliie (and otlier tiiiorides), tysonite, bastnasite. Gilpin Co — Near Central City, pyiite in mociiied crystals, chalcopyrltc oiten coated by tetraiiedrite in parallel jxisit.on, crystallized gold on pyrite. Gunnison Co. — Near Gotliic, smalt, te. JcyFERSON Co. — Near Golden, in basalt of 'I'able Mountain, cht-bazile, thomsonite, analeite. apophyllite, calcite, mesolite, laumontite. La Plata Co. — Poughkeepsie Gulch, Alaska mine, alaskaite with tetrahedite, chalco- pyrite, barite. Lake Co. — Tjeadville, eerussite carrying silver, anglesite, pyromorphite, sphalerite, calamine, minium, dechenite (?), rhodochiosite with galenite, chakopyrite. Golden Queen mine, scheelite with gold. Ute and Ule silver mine, stephanite, galenite, sphalerite, chalcocite. Park Co.— Grant P. 0., Baltic lode, beegerite. Hall Valley, ilesite. CALIFORNIA. Inyo Co. — San Carlos, datolite with grossular garnet and vesuvianite. Los Angeles Co. — Brea Ranch, vivianite in nodules with asphaitum. OREGON. Douglas Co.— Cow Creek, Piney Mountain, considerable deposits of a hydrous nickel silicate, allied to garnierite. Grant Co. — Canyon City, cinnabar with calcite. UTAH. Iron Co.— Coyote District, orpiment and realgar in a thin bed in the horizontal sediment- ary formations underlying lava. Piute Co. — Marysvale, onofrite. Salt Lake Co. — Butterfield Canon, mallardite, luckite. Wahsatch Range, head waters of Spanish Fork, ozocerite in considerable beds. NEVADA. Elko Co. — Emma mine, chrysocolla; Blue Hill mine, azurite, malachite. Lander Co. — Austin, polybasite, chalcopyrite, azurite, whitneyite. Lincoln Co. — Halite, cerargyrito. Nye Co. — Anglesite, stetefeldtite, azurite. eerussite, silver ore. cerargyi'ite. White Pine Co. — Eberhardt mine, cerargyrite; Paymaster mine, freieslebenite. NEW MEXICO.* Dona Ana Co. — Lake Valley, cerargyrite in the Sierra mines in large masses, rarely crystallized, associated with embolite, cenissite, galenite, vanadinite in small canary-yellow crystals, native silver, pyrolusite, manganite, fluorite, ankerite, apatite, chert. Victoria mine, 40 miles below Nutt, massive anglesite. Kingston, in Black Range, argentite in large masses. Socorro Co.— Socorro Mt., 3 miles from town of Socorro, large veins of barite carrying cerargyrite, vanadiferous mimetite, vanadinite in barrel-shaped crystals resembling pyromor- phite. Magdalena Mountains, 27 miles west of Socorro, eerussite in heavy veins Avith galenite, sphalerite, etc. Green and blue calamine on the Kelly location. Sophia mine, stromeyerite? Grafton, on a large quartz vein, Ivanhoe mine, gold in black eerussite, , chalcocite, bornite, malachite, azurite, chalcopyrite, cerargyrite, amethystine quartz. New Elk Mountain, 100 miles south of Socorro, eerussite carrying silver. *The author is indebted for the following notes, as also for others under Arizona and Montana, to Prof. B. Silliman. AMERICAN LOCALITIES. 507 Grant Co. — Silver City, Bremen's mine, argentite, eerargyrite. argontite pseudomorph of mollusca, barite with corargyrite, native silver in filagree and denclrites on slate; Santa Rita copper mines, native copper, tenorite. jMogoUon and Burro mountains, Coony mining district. Dry Creek; in Mundo mine, melaconite; Silver Twigg mine, bornite, copper; Alba- tross mine, bornite, malachite; Cooney mine, chalcopyrite. azurite, bornite; Cliiton mine, native copper, cuprite, azurite, malachite, wuUenite. Georgetown, Naiad Queen mine, argentite pseudomorph of mollusca. cerargyrite, native silver in dendritic form on slate. San Miguel Co. — Cerillos, Mt. Chalchuitl, turquoise in tuff. In the Cerillos district are numerous minei-al veins, carrying silver lead and salts of lead, rarely wulfenite and vanadinite, azurite, malachite, sphalerite, etc. ARIZONA. In the Silver District, Yuma Co.. at the Hamburg, Princess and Red Cloud mines, in connection with quartz veins carrying arg'entifei'ous galena, fine ruby-red vanadinite, red wulfenite, massive anglesite. Silent District, Black Rock mine, vanadinite. At the Castle Dome mines, vanadinite, mimetite, wulfenite, cerussite, galenite, fiuorite. Also wulfenite at the Melissa mine and Rover mine. In the Vulture District (also called White Picacho District^ Yavapai and Maricopa Cos.. numerous veins of gold-bearing cjuartz, carrying lead. Vulture mine, eryst. gold, jarosite, wulfenite. Hunter's Rest mine, gold in tourmaline rock. Fai'ley's Collateral mine, and tlie Phenix mine, 20 miles north-east of Vulture, yellow vanadinite with calcite, wulfenite, cerussite, descloizite (?), volborthite (?) crocoite, vauquelinite, phojni- cochroite. Montezuma mine, vanadinite, cerussite. Sante Domingo mine, mimetite, argentite. Silver Star mine, native silver, cerussite, argentite, crocoite, vanadinite. Tiger mine, native silver, cerargyrite. Tip Top mine, native silver, sphalerite, argentite, pyrargyrite. From the Rio Verde, Maricopa Co., thenardite in large deposits. Mohave Co. — Moss lode, gold in crystalline plates; fiuorite a frequent gangue material. Pinal Co — Mule Pass, Bisbey, Copper Queen mine, native copper, copjwr oxide, mala- chite, azurite, calcite. From the Silver King mine. Pioneer District, Pinal Co. — Fine crystallized native silver, argentite, sphalerite, pyrite. Stonewall Jackson mine, cryst. silver, argentite. From the Bon Ton mines, Chase Creek, neyr Clifton, dioj^tase with cuprite and limonite. MONTANA. Butte Co. — Butte City, Alice silver mine, rhodonite, a common gangue of native silver and other silver ores, rhodochrosite. Same in Magna Charter mine. Parrot, Mountain, Bell, and other copper veins yield various copper salts and arsenical copper glance with silver. " Original Butte mine," wurtzite with pyrite. Clear Grit mine, native silver, argentite, chalcopyrite, s])halerite, calcite, rhodochrosite. Colusa mine, chalcocite. ALASKA. Ft. Wrangell at mouth of the Stickeen River, fine garnets in mica schist. CANADA — Province of Quebec, Montreal. — Analcite, sodalite, nephelite (in nephelite-syenite). Ottawa Co. — Veins carrying apatite and pyroxene in large quantities are common in Buckingham, Burgess, Templeton, and other townships; also calcite, quartz, amphibole, scapolite, garnet, tourmaline, titanite, zircon, orthoelase, phlogopite and other species. Templeton, vesuvianite, garnet (cinnamonstone), pyroxene. Hull, colorless garnets, vesuvianite, white pyroxene. Wakefield, chrome garnet. CANADA— Province of Ontario. Frontenac Co. — Scapolite, apatite. Renfrew Co. — Eganville, large crystals of apatite, titanite, zircon (also twins), amphibole. 508 APPENDIX. NOVA SCOTIA. Cumberland Co. — Alunogen. Colchester Co. — New Annan, covellite. Klngs Co. — Black Koek, in tru]) with stilbite, ulexite, heulandite. CANADA — Keewatin District. Churchill River. — Lazulilc. KyEE Lake. — Magnetite Island, magnetite. CANADA — British Columbia. Cariboo District. — Native gold, galenite. On Frazer River.— Gold, argentiferous tetraliedrite, cerargyrite, cinnabar. North T.'ioinpson River, cyanite. Ho>VE Sound. — Bornite, chalcopyrite, molybdenite, mica. O.MiMicA District. — Gold, galenite, silver, silver amalgam. Cassi.\r District. — Gold. Texaea Island. — "Magnetite. QuEE>" Charlotte Islands. — Skincuttle Inlet, Harriet Harbor, magnetite, chalcopyrite. APPENDIX E. TABLES TO ]3E USED IN THE DETERMINATION OF MINERALS. TABLE I. Minerals arranged according to their Physical and ISlowpijye Characters. Thk following table is intended especially for use in instruction in Mineralogy. With thJa end in view it is limited to those species described in full in the body of this work, aLi the method of arrangement has been made to conform as nearly as possible to the chemical sys- tem of classification there followed. Table II., on the contrary, is made to embrace all species whose crystalline system is ^owu : General Scheme of Clnsitificnlion. I. MALLEABLE, OR EMINENTLY SECTILE. Many of the native metnU are here included. 1. Lustre metallic. 8 Lustre unmetallic. IL VAPORIZABLE, OR B.B. EASILY YIELDING FUMES, '^\xe sulphides, seleiudet, etc., also the sulpharsenite», sulphantimonitee, etc., are here Ifl eluded; also some native metals. Part I. Wholly Vaporizable. 1. Lustre unmetallic. 2. Lustre metallic. Part II. YiELDrNG Fumes readilt, but not wiiolly V kvoux7..\uxm. 1. Lustre unmetallic. 2. Lustre metallic. III. NOT MALLEABLE; NOT VAPORIZABLE, NOR EASILY YIELDING FUMES. Part I. LuarnE Metai-lic. 1. Streak unmetallic. — A. Infusible or nearly so ; B. Fusible. 2. Streak metallic. Part II. LusTUE UnmeTalhO. 1. Carbonates. a. Infusible. h. Fusible. • 510 APPENDIX. 2. Sulphates. 1 Soluble in water, or having taste. 2 Insoluble in water. 8. Chromates. 4. Silicates, Phosphates, Oxides (pt.), etc., oto> I. Streak Col/)r(.d. 1. Infusible, or nearly so. 2. Fusible. — A. Gelatinize with acids ; B. Do not gelatinize. II. Streak Uucobred. 1. Infusible. — A. Gelatinize with acids ; B. Do not gelatinize. 2. Fusible. — A. Gelatinize with acids. a Hydrous; /3 Anhydrous. B. Do not gelatinize. o Hydrous ; ;8 AnhydrouS. I I. MALLEABLE OR EMINENTLY SECTILE. 1. Lustre metallic. (a) Yieldins? B.B. no fumes.— Gold; Silver; Platinum; PALLADroM; Copper; Iron (pp. 221-220). (^) Yielding with soda ^n charcoal a silver globule. — Argentite (p. 235), and Acan- THITE (p. 239); yield also sulphurous fumes. — Hessite (p. 239), also telluric fumes. 2. Lustre tinmetallic. On charcoal a silver globule. — Cebargyrite (p. 260). IT. VAPORIZ ABLE ; B.B. yielding fumes in the open tube; some require to be strongly heated. Part L Wholly Vaporizable; readily passing away in fumes when heated on charcoal (if pure and free from gangue). 1. Lustre Unmetallic. 1. Fumes sulphurous; burning with a flame. — Sulphur (p. 228). 2. Fumes antimonial. — Valbntinite, senarmontite (p. 284). 3. Fumes arsenical. — Realgar (p. 2.J1), color red; Orpijient (p. 231), color yellow. 4. Fumes mercurial. — Cinnabar (p. 240). 2. Lustre Metallic. 1. Fumes sulphurous; with also fumes of antimony, bismuth, etc.— Stibnite (p. 232); BiSMUTHiNiTE (p. 2;)2): some tetradymite (p. 233). 2. Fumes selenial or telluric. — Clausthalite (p. 236); Tetradymite (p. 233^. 3. Native Arsenic, Antimony, Bismuth, and Tellurium (pp. 226, 227.) Some Cinna- bar (see above) has a metallic lustre. Part II. Yielding Fumes Readily in the open Tube, but not Wholly Vaporizable. 1. LU8TBE UNMETALLIG. 1, Fumes sulphurous alone.— Sphalerite ^p, 237), infusible; Greenookite (p. 242). 2. Fume.s sulphurous, and (a) antimonial; or (^) arsenical, yield a bead of silver with Boda on charcoal.— (a) Miarqyrite (p. 219); Pyrargvrite (p. 252) — (^) Pboustite (p. 253). determination of mineral8. 511 2. Lustre Metallic. 1. Fumes arsenical. a. On charcoal a magnetic bead or mass, (a) In the closed tube unaltered. — Coualt-- ITE (p, 24(3). (/3) Do., a sublimate of arsenic sulphide. — Aesenoptrite (p. 247), color silver-white, yields also metallic arsenic; Gersdorffite (p. 246), color silver-white to steel-gray, B.B. decrepitates; Tennaktite (p. 256), color iron-black, (y) Do., a faint white crystalline sublimate of arsenous oxide. — Niccolite (p. 242), color pale copper-red. b. With soda on charcoal a malleable bead of metallic lead. — Saktorite (p. 250), decrepitates strongly, G=5'39; Dufrexoysite (p. 251), G=5-56. c. Do., metallic copper. — Domeykite (p. 234), color tin-white to steel-gray; Enar- GITE (p. 257), color iron-black. 2. Fumes antimonial. a. With soda on charcoal yield metallic copper. (The bead obtained may also be tested with borax.) (a) Contains copper and lead. — Boxjrnonite (p. 253), color steel-gray, G.=5'7-5-9. (p) Contains copper and silver. — Polybasitb (p. 357), color iron-black, {y) Tetrahedrite (p. 255). b. Yield silver or lead but no copper, (a) Contain silver. — Dyscrasite (p. 234), G. =9*4-9 8, color and streak silver-white; FREiESLEBEJsaTE (p. 252), G. =6-6-4, color and streak light steel-gray, yields also sulphurous fumes; — Stephaxite (p. 256), G.=6'27, color and streak iron-black;' Pyrargyrite (p. 252), and Miargyrite (p. 249), have both a red streak, (/s) Contain lead ;— Zixkexite (p. 250), G. =5 '30-5 35; Jamesoxite (p. 251), G.=5-5-5-8; Boulangerite (p. 254), G.=5-75-6. 3. Fumes sulphurous. a. Reaction for copper with borax. — Chalcopyuite (p. 244), color brass-yeUow; BoRNiTE (p. 237), color copper-red to pinchbeck-brown on the fresh fracture; Chalcocite (p. 239), color blackish lead-gray; Stromeyerite (p. 240), color dark steel-gray, contains also silver. b. Yield a magnetic bead or mass on charcoal, (a) Yield free sulphur in the closed tube.— Pyrite (p. 243), G.=4-8-5-2; Marcasite (p. 247), G.=:4-7^-8; some linna?ite (see below). (3) Unchanged in the closed tube. — Pyrrhotite (p. 241), color reddish bronze- yellow, magnetic; Millerite (p. 241), color brass-yellow, with borax a nickel reaction; Lin- N.a;iTE (p. 245), color pale steel-gray, contains cobalt. c. Yields metallic lead on charcoal. — Galexite (p. 235), color lead-gray. d. Not included in the above. — MoLYBDExaTE (p. 233). 4. Fumes mercurial. — Amalgam (p. 225). 5. Fumes telluric, (a) Contain silver or gold. — Sylvanite (p. 248), color steel-gray to silver-white, brittle; Hessite, Petzite (p. 238), color lead to steel-gray, sectUe. (/3) Con- tains lead. — Nagyagite (p. 249), color black lead-gray, foliated. m. NOT MALLEABLE; NOT VAPORIZABLE, NOR EASILY YIELDING FUMES. Part I. Lustre Metallic, or Submetallic. 1. Streak Unmet allic. A. Infusible, or Fusible mt% great difficulty. a. Reaction for manganese with borax. {a) Anhydrous.— VT&oiM^itt. (p. 278), G.=4-83. S.=S-2-5, streak black (brau. nlte, hausmannite, (p. 277); Franklinite (p. 273), often in octahedrons, G. = 5 07, H. = 5'5-6*5; streak dark reddish- brown; yields zinc B.B. Some Columbite (pp. 360, 423). (/3) SycZroiis.— Manqanite (p. 280); PsilomeLane (p. 283); Wad (p. 383). 513 APPENDIX. &. Reaction for iron : become magnetic upon ignition in R.F. (a) Anhydrous. — Magnetite (p. 272), streak black, magnetic ; Hematite (p. 268), streak cherry-red. Contain titanium. — Menaccanite (p. 269), G. = 4-5-5, streak black to brownish-red; Rutile (see d below). Contain tantalum or columbium. — Tantalite (p. 359), G. =7-8; Columbite (p. 360), G.5'4-6'5. Contains chromium. Chromite (p. 274), streak brown. (?) Hydrous. — Limonite (p. 280), streak yellowish-brown, G.=3"6-4. only massive; QOthite (p. 280), streak same, G.=4-4-4, often in crystals; Turgite (p. 279), streak red, decrepitates stronglj^ B.B. c. Reaction for zme on charcoal. — Zincite (p. 266), streak orange-yellow. d. Reaction for /iVawmm. — Rutile (p 276); Octahedrite (p. 277); Bkookite (p. 277); Pkrofskite (p. 270). — Euxenite (p. 302), contains columbium. e. No reactions as above. — Yttrotantalite (p. 361). B. Fusible. a. Reaction for *Vo?i, become magnetic. — Ilvaite(p. 309), G.=3'7-4"2; Allanite (p. 308), G. = 3-4-2; WoLFR.\MiTE (p. 383), G.=71-7-5; Samarskite (p. 361), G.=5-45-5-69. b. Reaction for copper. — Tenorite (p. 267) ; Cuprite (p. 266). 2. Streak Metallic. No metallic bead. — Graphite (p. 230) ; Iridosmine (p. 224). Part II. Lustre Unmetallic. 1. CARBONATES : when pulverized effervesce (give off COa) with hydrochloric or nitric acid, sometimes only on the addition of heat (p. 202).* 1. Infusible. a. No metallic reaction, or only traces; assay alkaline (p. 205) after ignition. (a) Anhydrous. — Effervesce freely in the mass in cold dilute acid ; CalciTe (p. 398), G.=2-5-2-8; Aragonite (p. 405), G.=2'9; Barytocalcite (p. 408), contains barium. Effer- vescence wanting or feeble, unless very finely pulverized or heated; Dolomite (p. 401); Magnesite (p. 402). (/3) Hydrous. — Hydromagnksite (p. 409). b. A decided reaction for iron; become magnetic upon ignition. Siderite (p. 403) ; Ankerite (p. 402). Also mesitite, pistomesite (p. 403), and some varieties of the preceding carbonates. c. A decided reaction for manganese with borax. Rhodochrosite (p. 403). Also some varieties of the preceding carbonates. d. Reaction for zinc on charcoal. (a) Anhydrous. — Smithsonite (p. 44). (P) Hydrous. — Hydrozincite (p. 410). 2. Fusible. a. No metallic reaction, or only traces ; assay alkaline after fusion. (») Anhydrous. — Withbrite (p. 406), G.=4'3, B.B., a green flame (baryta); Stron- TIANITE (p. 406), G. =3'6--7, B.B., a strontia-red flame. {P) Hydrous.— GrAY'hVssnE {p. 409); Trona (p. 408). 6. Reaction for lead on charcoal. Cerussite (p. 407); Phosqenite (p. 408), contains lead chloride; Leadhillite (p. 390) contains lead sulphate. c. Reaction for copper with borax. Hydrous.— MALAcniTE (p. 411), color green; Azurite (p. 411), color azure-blue. d. Reaction for bistnuth on charcoal. Hydrous. — BisMUTiTE (p. 412). * Nitric acid is needed only in the case of lead salts (cerussite, phosgenite, leadhillite). In addition to the proper carbonates, also leadhillite and cancrinite effervesce with acid, and with many minerals effervescense may be caused by a mechanical admixture of calcite {e.g., wollastonite), or some other carbonate (e.g., lanarkite). DETERMINATION OF MINERALS. 513 2. SULPHATES : Yield a sulphide with soda on charcoal (p. 309),* which when moistened blackens a surface of polished silver. 1. Soluble in Water ; having taste. a. Glaubertte (p. SOI); Mirabilite (p. 39'2) ; Polyhalite (p. 393); Epsomite (p. 394): Alums (p. ^95). h. Copperas group : Vitriols. — Chalcanthite, etc. (p. 394.) 2. Insoluble in Water : having no taste. a. Yield no metallic bead. Fusible; slss&y alkaline atlQi: fusion. (a) Anhydrous. — Barite (p. 387), G.=4-3-4'7, a yellowish-green flame B.B. ; Celes- TiTE (p. 388).G.=3-92-3-97, a strontia-red flame B.B. ; Anhydrite (p. y89), G.=:2-9-2-99. a reddish-yellow tlame. ((3) Hydrous: Gypsum (p. 392), H. = 1-5-2, G.-2-3. b. Reaction for aluminum ; a blue color with cobalt solution after ignition. Hydrous : Aluminite Cp. 395). €. Reaction for lead on charcoal. i^Hs/^^e.— Anglesite (p. 389); Leadhillite (p. 390), contains lead carbonate. d. Reaction for copper with borax. Brochantite (p. 396); Linarite (p. 396). e. Reaction for iron : becomes magnetic after ignition on charcoal. COPIAPITE (p. 395). 3. CHROMATES : Afford a chromium reaction with borax (p. 208). All brightly colored, and having a colored streak. Crocoite (p. 385), color hyacinth-red, streak orange-yellow ; Phcenicochroite. (p. 386), color cochineal- to hyacinth-red, streak brick-red ; Vauquelinite (p. 386), color green to brovra, streak greenish or brownish. 4. SILICATES, PHOSPHATES, OXIDES (in part), etc I. Streak Colored: having a decided color. 1. Infusible, or Fusible with great Difficulty. a. Reaction for iron, magnetic after ignition in R.P. (») Anhydrous.— 'R.miA.TVi^ (268), streak cherry-red ; some Rutile (see e below). (/3) Hydrous. — Limonite (p 280), streak yellowish-brown ; Gothite (p. 280), streak same ; Turgite (p. 279), streak red, decrepitates B.B. h. Reaction for manganese with boras. Hydrous.— ^' XD (p. 283); Psilomelane (p. 282). c. Reaction for zinc on charcoal. ZiNciTE (p. 266) ; streak orange-yellow. d. Reaction for copper: yield metallic copper with soda on charcoal. Hydrous. — Dioptase (p. 301), color emerald-green. e. Reaction for titanium : with metallic tin on evaporation a violet color to the hydro- chloric acid solution, sometimes after fusion with potassium bisulphate. . Rutile (p.) 276), G.=4"2;Warwickite (p. 3S2), G.— 3-3, moistened with sulphuric acid gives a green flame B.B. (boron).— Some Pyrochlore (p. 359); and Perofskite (p. 270). /. Reaction for tin : yields the metal with soda on charcoal. Cassiterite (p. 275), G. =r6-4-7-l. g. Not included in the above. (a) Phosphates : moistened with sulphuric acid give a bluish-green flame B.B. — Monazite (p. 368). G.=4'9-5-26; Xenotime (p. 364), G.=:4-4o-4-56. (^) Pyrochlore (p. 359), G.=4-2-4-35 ; Fergusonite (p. 362). * Note the precaution on p. 209 ; it may be remarked in addition that, in the ease of a sulphate, the reaction is generally so decided that there can be no ambiguity, even when the gas contains a little sulphur. In all cases the soda on charcoal should be first tested alone 83 514 appendix. 2. Fusible without very great Difficultt, A. Gelatinize ivith Acid {p. 203). Give a reaction for iron. Ilvaite (p. 309), yields little or no water, H. =5*5-6, G. =3-7-4 -2, streak black, HisiNGERiTE (p. 354), yields much water, H.=3, G. =3*045, streak yellowish-brown; Allaxite (p. 308), H. =5*5-6, G. =3-4-2, streak gray. B. Do not Gelatinize icith Acid. 1. Arsenates: give arsenical fumes on charcoal ; after thorough roasting yield metallic reactions as follows: a. Reaction for iron : becomes magnetic after ignition. Pharmacosiderite (p. 376 >, color olive-green to yellowish-brown stc. h. Reaction for cobalt with borax. Erythrite (p. 372), color rose-red. c. Reaction for copper with borax; also give a green flame B.B. ITydroiis. — Olivexite (p. 373), G. =4*1-4-4, color olive-green to brown ; Lieoconite (p. 374), G.=2-88-'2-98, color sky-blue to verdigris-green; Clinoclasite (p. 374), G.=3-6-3-8, color dark-green (some libethenite, see lielow). 2. No arsenical fumes; reaction for iron : become magnetic after fusion. a. Anhydrous.— B.QB.ciioniov titaniHin: Schorlomite (p. 337), H. = 7-7-5, G. =3*862. massive. — Reaction for manganese: Triplite (p. 869), H. =3-44-3*88, G. =4-5*5, colors the flame bluish-green. — Str'uture micacecous : Lepidomelane (p. 313). h. HijdroKS.— Give a bluish-green flame B.B. : Vivianite (p. 371), H. =1-5-2, G.= 2-58-2-68, streak colorless to indigo-blue (on exposure); Dufeenite (p. 378), E. =3*5-4, G. =32-3-4, streak siskin-green. 3. No arsenical fumes; reaction for copper with borax, yield an emerald-green flame B.B. (a) Anhydrous. — Cuprite (p. 266) ; Tenorite (p. 267), color steel-gray to black. l?) Hydrous. — Structure micaceous; Torbernite (p. 378), H.=2-2 5, G. =34-3-6, — Libethexite (p. 373), H.=4, G.=3-6 3-8; Pseudojiaxachite (p. 374), H.=4 5-5, G.= 4-4-4; ATACAMiTE(p. 261), H.=3-3-5, G.=3-8 II. Streak Uncolored ; sometimes slightly grayish, yellowish, etc. 1. Infusible, or Fusible with much Difficulty. A. Gelatinize with Acid forming a stiff Jelly. a. Reaction for iron with the fluxes. Chrysolite (p. 300); Choxdrodite, Httsiite (p. 326-329), yield fluorine. h. Reaction for zinc on charcoal, after being heated with soda, (a) Anliydrcus. — Willemite (p. 301). (^) ^^rfrows.— Calamine (p. 329). c. Reaction for aluminum ; a blue color with cobalt solution after ignition. Allophane (p. 341), amorphous. d. Reaction for magnesium: pink color with cobalt solution after ignition. Sepiolite (p. 349), in soft, white, compact masses. B. Do not form, a perfect Jelly mth Acid. 1. Hydrous, a. Reaction for aluminum : a blue color with cobalt solution after ignition. 1. Phosphates : give a bluish-green flame B.B.. especially after being moistened with sulphuric acid. — Wa vellite (p. 376), color white to green to black ; Lazulite (p. 375), DETERMINATION OP MINERALS. 515 color azure-blue, -with borax an iron reaction; Turquois (p. 377), color sky-blue to apple- green, with borax a copper reaction. 2 Hydrous s/A'ca/t'^-.— Structure micaceous; Margarite (p. 357), yields much water; also some hvdroiis micas (see p. 353). Kaolinite (p. 351) usually compact, soft, unctuous; Pykophyllite (p. 349), soft, yields much water. 3. act(/?5.—GiB3SiTE (p. 28-3), n. =2-5-3 5, usually in stalactitic forms ; Diaspore (p. 279), H. = (>-5-7, in crystals, scales, and foliated, usually decrepitates B.B. h. Reaction for maf/ncsiuin: a pink color with cobalt solution after ignition. Brucite (p. 281), soluble in acids; Talc (p. 348), yields water only on intense igni- tion. Also some serpentine [see below). c. No reactions as above. Opal (p. 28-), H.= 6-7. —Serpentine (p. 350). H.=2-5-4; Chloritoid (p. 358), H.=5-5-G: Gexthite (p. 351), yields a reaction for nickel with borax.— Chrysocolla (p. 338), H.=2-4, colors the flame emerald-green (copper). 2. Anhydrous. a. Reaction for aluminum : (When of great hardness, pulverizing is necessary). (tt) Decomposed by acids. — Leucite (p. 318), H. =5.5-6. (/S) Structure eminently micaceous. — Muscovite (p. 313). (y) Corundum (p. '^67), H. =9. G. =4, rhorabohedral. Chrysoberyl (p. 274), H. = 8-5, G. = 3-7, color green. Topaz ip 332), H. = 8, G.=3 5. in prisms of 124°, cleavage basal perfect. Rubellite (p. 3:!0), H. =7-5, G.=3, in three- or six-sided prisms, color violet, rose- red, reaction for boron (p. 211). ( AxDALusiTE (p. 331). H.=7-5, G. =3-2, in prisms of 93°. • ■] Fibrolite (p. 331), H. =6-7. G. =3-2. brilliant diagonal cleavage. (Cyanite (p. 332j, H. =5-7, G. =36, usually in bladed crystals, color blue to gray. b. Reaction for magnesium : a pink color with cobalt solution after ignition. Talc (p. 348), soft, foliated, yields water upon intense ignition. Enstatite pt. (p. 2!t0), H.=5-5, cleavage prismatic 93°. Spinel pt. (p. 271), H.=8, commonly in octahedrons. c. Reaction for tin : metallic globules with soda on charcoal. Cassiterite (p. 275), G. =6-4-7-l. Also some Pyrochlore (p. 359). d. No reactions as above. 1. Hardness 7. or above 7. Spinel (p. 271), H.=8, G=3'5-4-l, occurs in octahedrons. Gahnite (p. 272), H.=7-5-8, G.=4-4-4-9, octahedral, when mixed with borax gives a zinc coating on charcoal. Beryl (p. 299). H. =7-5-8, G.=2-6-2-7, always in hexagonal prisms. Phenacite (p. 301), H. =7-5-8, G. =3, rhorabohedral. OuvAROViTE (p. .304), H. =7-5, G.=3'5, color green, chromium reaction. Zircon (p. 304), H.=7o, G.=4 05-4-75, zirconia reaction (p. 213) often in square prisms. Staurolite (p. 336), H.=7, G.=3-4-3-8, always crystallized, Ja/=123°. loLiTE (p. 311), H. =7-7-5, G.=2-6, color blue! lustre glassy. Quartz ip. 284), H.=7, G.=2-6, and Tridyjiite (p. 2b8), G.=2-3. 2. Hardness below 7. (a) Give a bluish-green flame when moistened with sulphuric acid ; Xenotime (p. 864) ; MoNAziTE (p. 368); Apatite (p. 364). (^) Reaction for /(7a«7'u»i.—RuTii,E (p. 276); Brookite (p. 277); Octahedrite (p. 277), always in square octahedrons; Perofskite (p. 270). (y) Reaction for tungsten. — Scheelite (p. 384), Il.=6, G. =4-5-5. («) Not included in the above; Enstatite (p. 290)- Diallage (p. 293); Anthophyi- UTE (p. 295). 2. Fusible. A. Gelatinizing with Acid : forming a stiff Jelly upon Evaporation, 516 APPENDIX. 1. Hydrous. a. Hardness 5, or above 5. Datolite (p. 334), in glassy crystals, also rarely massive, never fibrous, fuses with a green flame (boi'on). Natrolite (p. 342), G. =2*17-2'25, fuses quietly and easily to a colorless glass. ScoLECiTE (p. 343), Thomsonite (p. 342), on fusion often curl up in worm-like forms. h. Hardness below 5. Gmelixite (p. 345), H.=4-5, in hexagonal or rhombohedral crystals. Phillipsite (p. 345), H. =4-4-5, in twinned crystals. Laumontite (p. 838), H.=3-5, becomes opaque on exposure. Pectolite and Analcite are decomposed by acid with the separation of gelatinous silica, but do not form a stiff jelly. 2. AnJiydrous. With hydrochloric acid give oflf sulphuretted hydrogen. Danalite (p. 302), with soda on charcoal gives a zinc coating, color flesh-red to gray. Helvite (p. 302), manganese reaction with borax, color yellow. With soda on charcoal a sulphur reaction. Hauynite (p. 318), color sky-blue. Sodalite (p. 317), reaction for chlorine. Wollastonite (p. 291), color white, lustre vitreous. Nephelite (p. 316), hexagonal. B. Do not form a perfect Jelly with Hydrochloric Acid, 1. Hydrous. 1. Structure eminently micaceous. Chlorites: Penninite (p. 355); Ripidolite (p. 356); Prochlorite (p. 357); laminffl tough but not elastic, colors green to black ; only partially attacked by acid. Vermieulites : Jefferisite (p. 855); also pyrosclerite, etc., colors mostly brown, yellow, also green, B.B. exfoliate largely, decomposed by acid with the separation of silica. Lepidomelane (p. 813), color black, yields a magnetic globule. AuTUNiTE p. (379), H. =2-25, color bright yellow. Fahlunite (p. 353), has a more or less distinct micaceous structure. 2. Structure not micaceous, 1. Reaction for iron: leave a magnetic residue on charcoal. (a) Arsenates : give arsenical fumes on charcoal. — Scorodite (p. 375), orthorhombic; Pharma<'osiderite (p. 376), isometric. (P) Phosphates : give a bluish-green flame after moistening with sulphuric acid. Childrenite (p. 377), reacts for manganese, fuses only on the edges, H. =4'5-5. ViviAXiTE (p. 371), H. = l'5-2, fuses easily to a magnetic globule. 2 Reaction for arsenic on charcoal. Pharmacolite (p. 370). 8. Borates : give a deep-green flame after moistening with sulphuric acid. Borax (p. 381); Boracite (p. 381); Ulexite (p. 381); Sussexite (p. 380). 4. Not included above. («) Hardness 5, or above 5 (apatite =5). Preunite (p. 340), H. = 6-6*5, color apple-green to white. Analctte (p 34:S), H.=5-5"5, fuses quickly to a clear glass. Pectolite (p. 337), H. =5, usually in aggregations of acicular crystals. Apophyllite (p. 340), H.=45-'5, B.B.. a violet-blue flame. DETERMINATION OP MINERALS. 517 (P) Hardness below 5. PixiTE (p. oi)2), H.=^2'5-3-5, compact. Pachnolite (p. 265), H. =2-4, yields fluorine. Chabazite (p. 344), H.=4-5, rhombohcdral. Apophyllite (p. 340), H.=4o-5, tetragonal. Harmotoime (p. o4C). H.=4-5, usually in compound crystals. Stilbite (p. 346), H.=;]-5-4. Heulandite (p. 347), H.=3'5-4. 2. Anhydrous 1. Yield metallic lead, with soda on charcoal. Pyromorphite (p. 366), color green, gives a bluish-green flame on fusion. Mimetite (p. 300), color yellow to brown, yields arsenical fumes on charcoal. Vanadinite (p. 367), color brownish-yellow to reddish-brown, with borax R.F. an emerald-green bead. Wulfexite (p. 384), color bright yellow to red, reaction for tungsten. 2. Reaction tor fluorine, with sulphuric acid. (a) Give a bluish-gi'een flame after moistening with sulphuric acid. Amblvgoxite ^p. 369), gives a hthia-rci) lOLlTE (p. 301) Lanthaxite (p. 410). . Talc (p. 348) Aspidolite (p. 312) Pyrophyllite ip. 349).. Phlogopite (p. 312). . . Haidingerite (p. 371). . . Prehxite (p. 310) Strengite (p. 437) Aragoxite (p. 40')i. . . . Anhydrite (p 389) Herderite (p. 3r.l) Villarsite (p. 34 Fluellite (p. 264) Danbiirite (pp. 311,424) Manganocaleite (p. 406). Diaclasite (p. 21)1) Kupfferito ip. 296) Seybertite (p. 358) T.vrolite(p. 3r4) Keddingite (p. 435) . . . Autuxite (p. 379) . . . . Anthophylijte (p. 295). Axdalusite ( p. 331) . . . HuMiTE (p. 327) MonticcUite (p. 300). . . . Eosphorite (p. 423). .. Childrexite (p. 377) . . Exstatite (p. 290) 2-41 2 -4-2 -63 1-3-5 2-5 3-3-5 2 -5-2 -59 5-5-6 2-52 2-3 2 56-2-67 7-7-5 2-a-2-67 2-5-3 2 -6-2 -8 1-1-5 2-72 1-2 2-75-2-9 1-2 2-78-2-85 2-5-3 2-85 1-5-2-5 2 -8-2 -9 6-6-5 2-87 3-4 2-93 8-5-4 2 -9-2 -98 3-3-5 2 98 5 2-99 4-5 3 3 7-7-35 3 04 4-5 3-0-) 3-5-4 8-08 5-5 3-3 1 4-5 8-3-1 1-3 3-10 3-3 5 305-3-19 2-2 5 3 1-3 -2 5-5 3-1-3 -2 75 3 1-3 -24 6-6-5 3-3-25 5-5 5 313 5 81&-3-24 4-5-5 3-1-3-3 5-5 Spec. Gravity Hardness, Uranocircite (p. 489). . Chrysobi<:ryl (p. 2741. Stroxtiaxite (p. 406) Knebelitc ip. 300) . . . . Libethexite (p. 373) . Bromlite (p. 406) Atacamite (p. 261) . . . Claudetite (p. 284)...- Hortonolite tp. 300)... . Celestite (p. 388). . . . Koepperite (p. 300) . . . . Sternbergite (p. 240) . . Cervantite (p. 284) Tepluoite (p. 800) Brook I te (p. 277) G(-)THITE (p. 2£0) Olivexite (p. 373) [Witherite (p. 406). . . iBarite I p. 3b7) iMolybdite (p. ^84).... Euxexite (p. 362) ... Polyni ignite (p. 362).. Polyorase (p. 362) .. . , I^schyxite (p. 362). . . Cotunnite (p. 261). . . . Valextixite (p. 284)., Descloizite (p. 867) .. , Pueherite (p. 367) Axglesite (p. 389) . . . Kentrolite (p 480). . . . Leadhillite (p. 390)., Cerl'ssite (p. 407). . . . Nadorite (p. 370) .Mendipite (p. 263) 3-53 3-5-3-84 8-5 3-6-3-71 3-5-4 3-71 6-5 8 6-3-S 4 37 4-4-5 8-76-3-9 3-3-5 3-85 391 6-5 3-9-3-98 3-3-5 3-98-4-08 5-5-6 4-21 1-1-5 408 4-5 4-4-12 5-5-6 4-03-4-23 5-5-6 4-4-4 5-5-5 41^4 3 4-3 3-3-75 4-3-4-7 2-5-3-5 4-5 1-3 4-6-5 6-5 4-7-4-85 6-5 5-1 5-5 4-9-5-14 5-6 5-24 soft. 5-57 3-5-3 5-84 3-5 591 4 6-1-6-39 2-75-3 619 5 6-26-6-44 2-5 6-48 3-3-5 7-02 3 7-7-1 2-5-3 B. Lustre Metallic (and Submetallic). !Spec. Gravity Hardness. 5-5-6 Jamesonite (p. 251) . . . Spec. Gravity 5-5-5-8 Hardness. Iltaite fp. 3)9) 3-7-4-3 2-3 Mangaxite (p. 280) 4-2-4-4 4 Chalcocite ip. 239) 5 5-5-8 2 5-3 Chalcostibite i p. 250). . . 4-25-5 3-4 COLUMBITE {p. 3C0) 5-4-6-5 6 Exaroite (p. 257) 4-44 3 Boukxoxite (p. 353) . . . 5-7-5-9 3-5-3 Epigenit^. (p. 25S) 3-5 Diaphorite (p. 332) 5-90 3-5-3 Spathiopyrite (p. 346). . 4-5 6-7 Glaucodot (p. 248) 6-0 5 Stibxite (p. 282). . . . 4-52 3 Aikinite (p. 254) 6-16-8 3-3-5 Famatinite (p. -258) 4-57 3-5 POLYBASITE (p. 257) 6-21 2-3 Klaprotholite (p. 251). . 4-6 2-5 Stepbaxite (p. 256). . . . 6-^7 2-2-5 Marcasite (p. 247) .... 4-7-4-85 6-6 5 Stromeverite (p. 240). . . 6-2-6-3 2-5-3 Livinsrstonite (p. 232).. 4-81 3 Woifachite (p. 247) 6-37 5-5 Stylot ypite (p. 254) .... 4-79 3 Arsenopvrite (p. 347).. . 6 6-4 5-5-6 Pyrolusite (p. 2T8). . . . 4-82 3-3 5 Jordanite (p. 25') 6-4 Wittichenite (p. 254). . . a 3-5 Geocronite (p. 257) 6-4-6-6 2-3 Guejarite (p. 4-28) 5-03 85 Alloclasite (p. 248) 66 4-0 Guanajuatite (p. 233) . . 5-15 1 BlS.MUTHfXITE (p. 232). . 6-4-7-2 3 Emplectite (p. 250) 5-1-5-26 3 3-5 Leucopvrite (p. 248) . . . 6 2-7-3 5-5-5 Zixkenite (p. 250) 5 35 3-3-5 Lollingite (p. 248) 6-8-8-7 Sartorite (p. 250) 5-39 3 Acaxthite (p. 239) 7-16-7-3 3-5 Samarskite (p. 861) 5-45-5-7 5-5-6 Taxtalite (i). 359) 7-8 6-6-5 Dufrexoysite (p. 251). 5 5-5-6 3 Hessite (p. 238) 8-3-8-6 2-3-5 Yttrotaxtalite (p. Krennerite (p. 430) .... 361) 5-4-5-9 5-55 Dysciiasite (p. 234)... 9 4-9-8 3-5-4 522 APPENDIX. CRYSTALLIZATION MONOCLINIC. A. LusTBK Unmetallic. Spec. Gravity Hardnci»8. Natron (p. 409) MiRABILITE (p. ;j93). . . Borax (p. iJBl) Copperas (p. ,^94) Gay-Ll-ssite (p. 4i)9). . Botryo<^<>ii (p. 395). . . . Whewcllite (p. 412).... Trona (|). 408) Hydroiiiiigriesite (p. 409) SCOLECITE (p. ;J43) Stilbite ipp. 34G, 437) Phillipsite (pp. 345, 433) Heuj.axuite (p. 347).. Gypsum (p. 3i)i) GlBBSITE (p. 2s2) Syngenite (p. 394) Laumontite (p. 338).. Epistii.bite (p. 347). . . Brevvstcritc (p. 347). ... Petalite ( p. 295) | IIar.moto.me (p. 346). . . j Ortuoclase (p. 321). . . | Viviasite (p. 371) Ripidolite (p. 356)... Pectoute (p. 337). . . . PUAH.M.XCOLITE (p. 370) Glauberite (p. 301). . . BioTiTE (p. 312), Lepi- DOLiiE and other Micas Muscovite (p. 813) Vaalite fp. 3.'»5) Wollasto-ntte (p. 291) Datolite (p. 334) IIyalopiiane (p. ;;22). . Prochlfji-ite (p. 357) . . . Corundoi)hilite(p. 35S). Isoclasite (p. 373) Cryolite (pp. 264. 424) ThornscnolitG (p. 4-38). . Paciinolite (p. 265). . . Leucophanite (pp. 300, 430) Maroauite (p. 357). . . A.MPfiiBoi.E (p 296 1. . . . Erytiihite (p. 372). . . Spec. Gravity llardnesK 1-42 1-1-5 1-48 1-5-2 1-72 2-2-5 1-8-2 -2 2-2-5 1-9 1-99 2-3 2-04 2-2-5 2-5-3 2-11 2-5-3 2-14-2i8 3-5 2 -1-2 -4 5-5-5 2 -09-2 -2 35-4 2-20 4-4-5 2-2 3-5-4 2 -3-2 -33 1-5-2 2-3-2-4 2-5-3-5 2 -25-2 -6 2-5 2-25-2-:;6 3-5-4 2-25-2-3fi 4-4-5 2-43 4-5-5 2 •4-2- 5 6-6-5 2-4) 4-5 2 -4-2 -6 6 6-5 2 -58-2 -68 15-2 2-6-2-8 2-2-5 2 -05-2 -8 5 2-6-2 73 2-2-5 2 6-2-85 2-5-3 2-7-3-1 2-5-3 2-7-3-1 2-2-5 2 -78-2 -9 4.5-5 2-8-3 5-5-5 2 -8-2 -9 6-6-5 2 -8-2 -96 1-2 2-9 2-5 2!}2 1-5 2-9-3 2-5 2-93-3 25-4 2-97 3-5-4 2-99 3-5-4-5 2-9-3 -4 5-6 2-95 2-2-5 I Wagnerite (p. 368). . . ' IKotti?ite (p. 372) Ludlamite (p. i>72). . . . , Spouumene (p. 295). . . j Lazulite (p. 375) ' i]ucLASE (p. 333) Herrengrunditeip. 428) Johannite (p. 397) Chondhouite (p. 327). Clinohu-mite (p. 328). . FiBRDLITE (p. 331). ... Allanite (\k ,308) Epidote (p. 307) Pyroxenr (p. 292) j iAcn;iie (p. 204) I Hoiriilite (p. 429) ^ Dickinsonite (p. 425).. . Piedmoritite (p. 308). .. Fillowite {p. 427) Kealoar ([). £31) TlTANITE (i>. 335) jEgirito (p. 294) I Keilhauite (p. 336) j AZURITE (p. 411) Barytocalcite ip. 408; Triploidite (p. 439) Chalcoinonite (p. 4-22). . Malachite (p. 411). . . Brociiantite (p. 396). Trogerite (p. 379) Durangitc (p. 370) Gadoliiiite (p. 309) I'yrostilpiiito (p. 252). . Clixoci.asite (p. 374). . Mo.nazite (p. 308), Tur- ner] to Miaroyrite (p. 249). . . LiNARITR (p. 390) Vauqitellnite (p. 386). Laxinannife (\>. 386). . . Walpurgite (p. 379)... Crocoite (p. 385) Lanarkite ip. 391) Calodonile (p. 391;. . . . Megabasite (p. 383). . . . Iliibnerite (p. 383) 3-07 3-1 312 3-1- -319 3-3 12 3-1 313 3-19 3-1-3-24 3-1-3 24 3-2-3-3 3-4-2 3-25-3-5 3-2-3-5 3-2-3 53 3-34 3-34 3 4-4 3-43 3-4-3-6 3-4-3 56 3 45-3-6 3-7 3-5-3-83 3-64-3-66 3-7 3-76 3-7-4-01 3-8-3-9 3-96 3-95-4-03 4-4-5 4-2-4-25 4-2-4-36 4-9-5-26 5 -2-5 -24 5-3-5-45 5-5-5-78 5-77 5-8 5-9-6-1 0-3-7 64 6-45 7-14 5-5 5 2-5-3 3-5 0-5-7 5-6 7-5 2-5 2-25 6-6-5 6-6-5 6-7 5-5-6 0-7 5-6 6 4-5-5 3-5-4 6-5 4-5 1-5-2 5-5-5 5-5-6 6-5 3-5-4 4 4-5-5 3-5-4 3-5-4 5 6-5-7 2 2-5-3 5-5-5 2-2-5 2-5 2-5-8 3 2 5-3 2-2-5 2-5-3 3 -.5-4 45 B. Lustre Metallic (and Submetallic). Allanite (p. 308).. , Clarile (p. 258) Crcdncrite (p. 278). . , Miaroyrite (p. 249) Plagionite (p. 251). . . Spec. Gravity Hardness.!] 3-4-2 5-5-6 4-46 3-5 4-9-5-1 4-5 5-2-5-4 2-2-5 ; 5-4 2-5 1 Mcneghiriite (p. 216).. . Freieslebe.xite ( p. 252) VVOLKRA.UITE (p. 383). . Sylvanite (p. 248). . . . Spec. Gravity Hardness, 6-34 6-6-4 7-1-7-55 8-8-3 2-5 2-2-5 5-5-5 1-5-2 DETERMINATION OF MINERALS. 523 CRYSTALLIZATION TRICLINIC. Sassolite (p. 380) Haiinayite (p. 428) Chalcanthite (p. 394). Wapplorite (p. 371) Microfline (p. 326) Albite (p. 323l Oligoclase (p. 3231. . . . Labradorite (p. 321). . MnxETiTE (p. 432) Andesite (p. 322) AXORTIIITE (p. 321) Spec. Gravity Hardness. 1-48 1 19 2-21 2-5 2-48 2-2-5 2-r)4 2 •09-2-6.) 6-7 2-6.")-2 69 6-7 2-67-2-76 6 275 3-5 i 2 -61-2 -74 6 ! 2 •66-3-78 6-7 Eggonite (p. 425) Amblygoxite (p. 369) . . Fairfieldito (\\ 426) AxiNiTE i\y 310) Hal)ingtoiiite (p. 295).. Cyanite (p. 332) KUODOXITE (p. 294). . . . Vcszclvite (p, 373) Rosclite (p. ;!72) ? Brochaxtite (p. 396\ Pseudoraiilaehite (p.374) Spec. Gravitj' Hardness. 3-3 11 3-15 3-27 3-3-3 -37 3-4-37 3 4-3-7 3-5 3-5-3-08 3-8-3-9 4-4-4 4-5 '5-7 5-6 -7-25 ■5-6-5 ■5 •5-4 5-5 ni. AUXILIARY TABLES. A. Minernh rvhose JJardness is equal to, or greater than, 7 (Quartz='T). Hardness. 7 Quartz (p. 284) Tridvmito (p. 288) Panhiirite (p. 311) 7 Boracite (ervstals) (p. 381) 7 Cvanito (p. 332) 5-7-25 Tourinalino (p. 329) 6-5-7-5 III. Garnet (p. 302) 6-5-7-5 I. Iolite(p. 311) 7-7-5 IV. Staurolite (p. 336) 7-7-5 IV. Sohorloiuite (p. 337) 7-7-5 — Cryst.* III. (R) III.? IV. I. VI. (R) Euelase (p. 333) Zircon (p. 314) Andalusite (p. 331) Beryl (n. 299) Plienacite (p. 301) Spinel (p. 271) Topaz (]>. 332) Chrysoberyl (p. 274) Corundum (p. 267) Diamond (p. 228) ardness. Crvst 75 V. 7-5 IL 7-5 IV. 7-5-8 HI. 7-5-8 111. ( 8 1. 8 IV. 8-5 IV. 9 III. ( 10 I. (R) (R) The following minerals have hardness equal to 6-7, or 6-5-7. Iridosmine, III. — Cassitorite, IE.; Diaspore, IV.; Clu-ysolite, IV.; Spodumone, V. ; Epidote, V. ; Ardeunite, IV. ; Gadolinite, V. ; Fibrolite, V. ; Feldspars, VI. ; Axinite, VI. B. Unmetallic Minerals which are distinctly foliated mj some of their varieties. 1. Micaceous: easily separable into very thin lamina\ flexible to slightly brittle. a. Micas (pp. 31 i to 315): laniiua» tough and elastic, except when they have uiuler- gone alteration; Anhydrous. Here are included tiie species: Phlogopite; Biotite; Musco- vite; Lepidolitc: Cryophyllite. Those graduate into the Hydro-jucas (pji. 353. 354), in which tiie lamina'' are inelastic and more or less brittle. Here belong: Fahlunite; i\Iargarodile; Damourite; Paragonite; Cookeite; Eu- phyllite; Oeliaclierile, etc. ; and related to these, ]\Iargarite. LeindonuMane is another mica (anhydrous or ne.-irly so) whose folia are nearly in- elastic. Astrophyllile is a micaceons nuMubcr of the jiyi'oxene family. 6. Chlorites (355 to 357): lamin;e tongli but mostly inelastic; hydrous ; color gen- erally dark-green. Here are included: Penninite; Hipidolite: Proclilorite, etc. Tiiese are related to the Vermicuettes (p. 355', in whicii the lamina^ are less tough, being more or less brittle: JelTorisite; Pyrosclerite, etc. c. Pyrophyllite. Talc, sometimes rather micaceous, lamina> .soft, and somewhat greasy to the feel. Brucite is related in character, but differs chemically in being soluble in acids. d. Torbernite, color deep-green; Autunite, color yellow to bright-green, lamina> brittle. * Ilore. as elsewhere, I. — Isometric; II. =Tetragonal; III. = Hexagonal; IV. = Ortho- rhombic; V — Mouoclinic; VI.=Tricliuic. 24 APPENDIX. 2. Not properly micaceous, though separable more or less easily into thin lamin?e. Chloritoid (p, 358) and Seybcrtito (p. 358) nre foliated, (ho lamina; not separating easily. So also Bronzite, Hypersthene, Diallage, and Marmolite. Gypsum sometimes occurs in soft, separable laminas (var. Selenite), slightly flexible Zincite and Erythrite are sometimes foliated but not separable. C. UnmetaHic Minerals ulu'ch in acme cf their varieties hate a fibrous structure. 1. Easily separable into flexible fibres. ix Asbestus (=araphibole) ; Crocidolite ; Chrj-sotile ( = serpentine) ; A nthrosid erite. 2. Fibrous, not easil^^ separable; structure ir-aduating into columnar." " ' Anhydrous Silicates: — Enstatite ; WoUastonite ; Fibrolite ; also, though more properlj columnar in structure : — Cyanite ; Epidote ; Tourmaline. Hydrous Silicates, ZeoUtes'mostlj : — Thomsonite ; Okenite ; Natrolite ; Scolecite ; Pecto- lite ; Carpholite. Also some Serpentine. Phosphates ; Arsenates : — WaveUite ; Cacoxenite ; Pharmacolite ; Dufrenite ; OIlTenite Vivianite ; Pyromorphite. Sulpliates: Anhydrite; Barite ; Celestite; Gypsum. Carbonates: — Calcite; Rhodochrosite ; Magnesite; Hydromagnesite ; Aragonite; Mala- chite. Also: — Brucite (nemalite); Sussexite; Ulexite. GENERAL INDEX TO MINERAL SPECIES Abriachanite, 420. Acadiulite, 344. Acaiitliite, 239. Achrematile, 385. Achroitc, 330. Acmito, 294. Actinclitc, 297. Adainiii'^ Adamite, 873; 420. Adelpholite, 3G3. Adular, Adularia, 825. ^girine, ^Egyrite, 294. Aerinite, ;:50. .^schynite, 362. Agalinatolite, 349, 352. Agaric mineral, 400. Agate, 286. Aglaite, 420. Ag:-icolite, 302. Aikinite, 25 i. A j kite, 4:; 5. Akimthit, v. Acanthite. Akmit, V. Acmito. Alabandite, v87. Alabaster, 393. Alalite, 293. Alaskaite, 420, Alaun V. Alum. Alaunstein, 396. Albcrtitc, 41(5. Albite 323; 420. Alexandrite, 275. Algodonite, 235. . Alrite, .'].•) 1. Alliinite, 308. Allemontitc, 227. Alioohroite, v. Andradite. AlJoclasite, 2-18. Allophane, 341. AUophite, 3-)6 Almandin, Almandite, 80]. Alshcdite, 438. Alstonite. ■». Broralite. Altaite, 237. Alum, Native, 835. Alumina -= Aluminum oxide. Aluminum carbonate. 410. chloride, 260. fluoride. 2(51, 265. fluo-silicate, 332. Aluminum hydrate, 279, 282. hydro - sulphate, 395. mellate, 412. oxide (Alumina), 367. phosphate, 875, 376, 877, 378, 439. silicate, 331, 383, 341, 349, 351. sulphate, 895, 896. Aluminite, 895. Alunite, 396. Alnnogen, 395. Amalgam, 225. Amazonstone, 325. Amber, 415. Amblygonite, 869; 430. Amblystegite, 290. Ambrite, 415. Arabrosine, 415. Amesite, 424. Amethyst, 286. Amianthus, 297, 350. Ammonia, v. Ammonium. Ammonium chloride, 260. oxalate, 433. phosphate, 371. sulphate, 392. Amphibole, 296; 420. Analcite, Analcime, 343. Anatase, 277. Andalusite, 331. Andesine, Andesite, 332. Andradite, 304. Andrewsite, 878. Aiiglesite, 889. Anliydrite, 889. Aniraikite, 420. Ankorite, 402. Aimabergite, 372. Annerodltc, 433. Annite, 313. Anomite, 431. Anorthite, 321. Antholite, v. Anthophyllite. Anthophyllite, 3t)5. Anthracite, 417. Anthracoxenite, 415. Aiitigorite. 351. Antillite, 351. Antimonblende, 284. Antiraonbliithe, v. Valentin ite. Antimonglanz, 232. Antimonite, 232. Antimonsilber, 234. Antimony, Arsenical, 227. Gray, 232. Native, 226. Red — Kermeslte, 284. White-Valentin- ite, 284. Antimony blende, 284, bloom, 284. glance, 232. oclire, 437. oxide, 284, 437. sulphide, 232. Apatite, 364; 420. Aphanesite v. Clinoclasite. Aphrite, 400. Aphrizite, 380. Aphrodite, 349, Aphrosiderite, 3r>6. Aphthalose,Aphthitalite,390. Apjohnite, 395. x\plome, 304. Apophyllite, 340; 421. Aquacrcptite, 351. Aquamarine, 299. Ara?oxene, 426. Aragonite, 405; 431. Aragotite, 414. Arcanile, 890. Arctolite, 421, Ardennjte, 310. Aroquipite, 421, Arfvedsonite, 298; 421. Argentine, 4 ,0. Argentite, 235. Argentopyrite, 437. Argvropyrite, 437. Arite, 243. Arkansite, 278. Arksutite, 365. 526 GENERAL INDEX. Arquerite, 225. Ariagonite, 405. Airheiiite, 421. Arsenargentite. 421. Arsencisen, v. Leucopyrite. Arseneisensinter, v. Pitticite. Arsenic, Aiitimonial, 227. Native, 22G. Red. 284. Yellow, 284. White, 2b4. Arsenic oxide, 284. sulphide, 231. Arsenical Antimony, 227. Arsenikkics, 247. Arsenikkupfer, 234. Arsennickclglanz, 24G. Arseuiosiderite, i]78. Arsenitc, v. Arsenolite. Arsenolite, 284. Arsenopyrite. 247. Asbestus, 297. Bliie.r. Crocidolite. Asbolan, Asbolite, 28vnite, 321. Cabrerite, 423. Cacholong, 389. Cacoxcnite, Caeoxene, 3T8. Cadmium sulphide, 243. Cairngorm stone, 280. Calaite. v. (,'allaite. Calamine, 339. 432; 404. Calaverite, 249; 423. Calcareous spar, tufa, 398 ; 400. Calcite. 398. Calcium arsenate, 370, 371. antimonate, 370, 421. borate, 383. boro-silicate, 334. carbonate, 39^^, 405. chloride, 2(i0. fluoride, 2Q'<. nitrate, 379. oxalate, 413. phosphate, 3C4, 371, 436, 433. silicate, 291, 338 ; 831. Bulphate, 389, 892; ;;91. sulphide, 235. Calcium tantalate. 359, 431. titanate, 270. tungstate, 384. Calcozincite, 367. Calc-sinter, 400. Caledonite. 391. Callais. Callaite, 377. Calomel, 260. Calvonigrite, 434. Campylite, 367. Canaanite = White Pyroxene. Cancrinite, 317; 422. Cannel Coal. 417. Capillary pyrites, 241. Caporciiinife, 338. Carbonado. 339. Carbon diamantaire, 229. Carnallite, 261. Carnelian, 2>-'6. Carpholite, 341. Caryinite, 432. Cassiterite, 275. Castor, Castorite, 295. Catapleiite, 339. Cataspilite. 353. Cat's eve, 2 6. Cavolinite, 316. Celadonite, 849. Celestialite, 435. _ Celestite, C'elestine, 388.^ Centrallassite, 338. Cerargvrite, 260. Cerbolite, 392. Ccrine, 3ii8. Cerite, 340. Cerium carbonate, 408. fluoride, 439. phosphate. 364, 368. silicates, 308, 330. Cerolite, 351. Cerussite, 407. Cervantite, 284. Cevlanite. Cevlonite, 271. Chabazite. 344; 423. Chalcanthite. 394. Chalccdonv, 286. Cha'cocite* 2y,9. Chalcodite, 350. Chalcolite, 878. Chalcoraenite, 422. Chalcomorphite, 841. Chalcophanite, 28:5. ChalcophylUte, 375. Chalcopyrite, 244; 422. Chalcosiderite, 378. Cha! cosine. 339. Chalcoslibite, 250. Chalcotrichitc, 266, Chalk, 400, Chalvbite, 403. Cliathamite, 34G. Chert, 287. Chesterlite, 326. [412. Chessy Copper, Chessylite, Chiastolite, 331. ChiUlrenite. 377; 422. Chiolite. 264. Chladnite. 390. Chloanthite, 245. Chloral luminite, 260. Chlor-apatite. 365. Chlorastrolite, 340. Chlorite Group. 355. Chloritoid. 358. Chloritspath. 358. Clilormagnesite, 260; 423. Chlorocalcite, 260. Chloropal, 350. Chlorophwite, 356. Chlorophane, 263. Chlorophvllite, 353. Chlorothionite, 2U0. Chloroti'c. 373. Chodnetiite. 364. Chondraisenite, 373. Chondrodite. 337; 423. Chonicrite, 355. Chrismatitc, 413. Chromeisenstein, 274. Chromglimmer, v. Puch- site. Chromic iron, 274. Chromite, 374; 433. Chrompicotite, 274. Chromium oxide, 374. sulphide, 242. Chrvsobervl. 374. Chrvsocolla, 338; 423. Chrysolite, 300; 423. Chrysoprase, 286. Chrvsotile, ;.50. Churchite, 371. Cinnabar, 240. Cinnamon stone, 303. Clarite, 358. Claudetite. 2S4. Clausthalite, 236. Clav, 351, ct seq. Cleavelandite, 824. Cleveite, 433. Clingmanite, 358. Clinoclasc, Clinoclosite, 374, Clinochlore, 356. Clinocrocite, 433. Clinohumite, 838. Clinophipite, 423. Clintonite, 358; 423. Cloantliite, 245. Coal, Mineral, 417. Boghead, 48. Brown, 418. Cannel, 417. Cobalt, Arsenical, 245, 246. Black (asbolite), 283. Earthy, 383, Grav (smaltite), 245. Red (ervthritc), 372. White (cobaltitc), 246. '628 GENERAL INDEX, Cobalt bloom, 373. glance, 246. arsenate, 373. arsenide, 246; 248. carbonate, 436. oxide, 283. selenite, 432. sulphate, 394. sulphide, 245. Cobaltine, Cobaltite, 246. Cobaltomenite, 432. Coecolite, 293. Coke, 417. Colestine, «. Celestite. Cceruleolactite, 376. CoUyrite. 341. Colophonite, 304. Coloradoite, 433. Columbite, 3(i0; 423. Comptonite, 342. Connellito, 8C1. Cookeite, 354. Copal, Fossil, 415. Copaline, Copalito, 415. Copiapite, 395. Copper, Antimonial (chal co- st ibite), 250. Arsenical, 234. Black (me! aconite), 2(i7. Blue, 411. Emerald (dioptase), 301. Gray, 255. Indigo, 249. ]Sative, 225. Purple, 237. Red, 266. Variegated, 237. Vitreous, 239. Copper arsenate, 373, 374, 375. arsenide, 234. arscnitc (?), 4:59. carbonate, 411. chloride, 2(;0. chromate, 380. glance, 339. mica, 375. nickel. 243. oxide. 266, 367, oxychloride, 261, 263. phosphate, 373, 374. pyrites, 244. selenide, 237. selenite, 423. silicate, 801, 33P. sulph-antimonite, 250, 254, 25.5, 257. 428. sulph - arscnite, 251, 256, 257, 25S. sulphate, 890, 894, 396. 397, 428. sulphide, 239, 249; 237, 244. Copper s u 1 p h - bismuthite, 250, 251, 254. tungstate, 384. vanadate, 874. vitrio', V. Chalcan- thite. Copper ore. Red, 266. Yellow, 344. Copperas, 394. Coprolitcs. 366. Coquimbite. 395. Cordieritc, 311. Cornwallite, 374. Coronguite, 434. Corundellite, 358. Corundophilite, 358; 424. Corundum, 267; 424. Corvnite, 247. Co.sa]ite, 252; 434. Cossaitc, 354. CossjTrite, 424 Cotunnite, 361. Covelline, Covellite, 249. Craigtonite, 424. Crednerite, 278. Orichtonite, 270. Crocidolite, 298. — ^ — Croc'Oite, Crocoisite, 885; 424. Cronstedtite. 357. Crookesite, 235. Cryolite, 264; 494. Cryophyllite, 315. Cryptohalite, 264. Cryptolite, 3(i4. Cryptomorphite, 382. Cuoan, Cubanite, 245. Culsagceite, 355. Cummingtonite, 297. Cuprocalcile, 411; 424. Cuprite, •.:66. Cupromagncsite, 395. Cupi-oscheclite, 384. Cuprotungstite, 384. Cuspidine, 424. Cyan i to, 332; 424. Cyunochaleite, 839. Cyanotrichite, 397. Cymatolite, 849, 436. Cyprusite, 424. Damourite, 353. Danaite, 248. Danalite, 3()3; 424. Danburite, 311 ; 424. Datholite, Datolite, 834. Daubreelite, 243, Daubreite, 363. Davids.nite, 299. Davreuxite, 435. Davync, Davina, 316. Dawsonitc, 410; 435. Dechenite, 367. Pegeroite, 354. Delessite, 356; 425. Delva-ixile, r. Bufrenite. I Demidoffite, 339. Derbyshire spar, v. Fluorite Deseloizito, 367; 485. Desmine, 346. Destinezite, 435. Dewalquite, 310. Deweylitc, 351. Biabantachronnyn, 355. Diabantitc, 355. Diaelasite, 291. Diadochite. 379. Diallage, Green, 293. Diallogite, Dialogite, 408 Diamond, 228; 425. Dianite, v. Columbite. Diaphorite, 252. Diaspoie, 279. Dichi-oito, 811. Dickinsonite, 425. Dietrichite, 425. Dihydrite, ;i74. Dimorphite, 232. Dinite, 414. Diopside, 293. Dioptase, 801. Dipyre, ;;16. Discrasite, v. Dyscrasits, Disterritc = Brandisite. Distheno, 332. Ditroyte, 317. Dog-Tooth Spar, 400. Dolcrophanitp, 880. Dolomite, 401. Domcykite, 234. Doppelspath, o99. Dopplerito, 415; 425. Douglasite, 425. Di-eelite, 390. Dry-bone, 404. Dudleyite, 358. Dufrenite. 378. Dufrenoysite, 251. Dumortierite, 425. Duporthile, 425. Durangite, 370. Diirfeldtite, 425. Duxite, 415. Dysanalyte, 425. Dvscrasite. 234. Dyshiite, 373. Dysodile, 415. Dysyntribite, 353. Earthy Cobalt, 283. Edenite, 297. Edingtonite, 341. Edwardsite, v. Monaaite. Eggonite, 425. Ehtite, 374. Eisenbliithe, 405. Eisenbrucite, 423. Eisenglanz, 268. Eisenglimmer, 260. GENERAL IXDEX. 529 Eisenkies, 24:]. Eisenkiescl, v. Quartz. Eisenrose. 2Gi). Eisensinter, v. Pitticite. Eisenspath, 403. Eisspath. SIQ. Ekilemitc. 4'25. Ekebergito, 316. Ekmannitc. 854. Elffiolite, 316. Elaterite, 414. Electruiii, 221. Eleonorite, 426. Ellonite,426. Elroquite, 426. Embolite, 260. Embrithite, «. Boulangerite. Emerald, ','99. Emerald nickel, 410. Emery. 268. Emplectite, 250. Emxrgite, 257. Enceladitc. v. Warwickite. Enophite, 436. Enstatite, 2S)0. Enysite, 397. Eosite, 385. Eosphorite, 423, Ephesite, 354. Epiboulangerite, 254. Epidote, 307. Epigenite, 258. Epistilbite, 347; 426. [426. Epsom Salt, Epsomite, 394; Erbsenstein, 400. Erdkobalt, 283. Erdol, 416. Erdpeeh, 416. Eremite, ®. Monazite. Erilite, 426. Erinite, 374. Eriochalcite, 426. Erubescite, 237. Erythrite, 372. Erythrosiderite, 261. Erythrozincite, 426. Esmarkite. 353. Essonite, 304. Ettringite, 395. Eucairite, 235. Eucbroite, 373. Euclase. 333; 426. Eucolite, 299. Eucrasite, 426. Eucryptite, 426. Eudialyte, Eudyalite, 299. Eudnophite, 344. Eugenglanz, t. Polybasite. Eiikairite, i\ Eucairite. Euklas, 333. Eulytine, Eulytite, 302; 426. Eumanite, 278. Euosmite, 415. Euphyllite, 354. Eusyncliite, 426. Euxenite, 362. Fahlerz. 255. Fahlunite, 353. Fairlieklite, 426. Famatinite, 258. Faserquarz, 298. Fassaite, 293. Faujasite, 314. Fauserite, : 9 L Fayalite, uwU. Feather ore 251. Federerz, ','51. Feitsui, 309. Feldspar Group, 319 ; 426. Felsite, 323, 326. Feldspath, ■». Feldspar. Fergusonite, 362; 4J7. Ferroilmenite, 360. Ferrotellurite, 427. Feuerblende, 252. Feuerstein, 287. Fibroferrite, 395. Fibrolite, 331. Fichtelite, 414. Fillowite, 427. Fiorite, 289. Fireblende, 252. Flint, 287. Float-stone, 2S9. Flos ferri, 405. Fluellite, 264. Fluocerite, 264. Fluor-apatite, 365. Fluor, Fluorite, 263; 427. Fluor Spar, 263. Flussspath, 203, Foliated tellurium, X). Nagya- gite, Fontainebleau limestone, 400. Foresite, 347; 427. Forsterite, 300. Fowlerite, 294. Francolite, 365. Franklandite, 427. Frank Unite, 273, Fredricite. 438. Freibergite, 255. Freieslebenite, 252. Frenzelite, 233. Freyalite, 427. Friedelite, 302. Frieseite, 437, Frigidite, 438, Fuchsite, 314. Gadolin, Gadolinite,309; 427. Gahnite, 272. Galena, Galenite, 235. Galenobismutite, 427. Galmei, 339, 404. Ganomalite, 427. Garnet, 802; 427. ' Gamierite, 351 ; 427. j Gastaldite, 298. I Guanovulite, 392. Gay-Lussite, 40!?. Gearksutite, 265. Gedanite, 435, Gehlenite. 331. Geierite, x. Geyerite. Gekrosstein, 389. Gelbbleierz, 384. Genthite, 351. Geocerite, 414. Geocronite, 257. Geomyricite, 414. Gersdorffite, 246. Geverite, 248. Ge'vserite, 289. Gibbsite, 282. Gieseekite, 352; 317. Gigaatolite, 353. Gilbertite, 353. Gillin^ite, 354. Ginilsite, 428. Girasol, 289. Gismondine, Gismondite, 341 ; 428. Giufite, 432. Glanakobalt, ■». Cobaltite. Glasei'ite, «. Arcanitc. Glaserz, Glanzerz, v. Argen- tite. Glauber salt, 392. Glauberite, 391. Glaucodot, 248. Glauconite, 349. Glaucophane, 298, Glimmer, v. Mica. Globulites, 110. Gmelinite, 345. Gold, 221. Gold telluride, 248, 249. 430. Goldtellur, v. Sylvanite. Goshenite, 299. Goslarite, 395. Gothite, 280. Grahamite, 416. Grammatite, 297. Granat, 302. Graphic tellurium, 248. Graphite, 230. Graukupfererz, v. Tennantite. Gray antimony, 232. copper, 255. Greenoekite, 2-12. Greenovite, 335. Grenat, «. Garnet. Grochauite, 357. Grossularite, 803. Griinauite. 237. Grunbleierz, 366. Guadalcazarite, 241. Guanajuatite, 233; 428. Guanipite, 433. Guano, 365. 530 GENERAL INDEX. Guarinite, 336. Guejarite, 428. Giimbelite, 353. Gum mite, 428. Gunnisouito, 428. Guyaquillito, 415. Gymnite, 351. Gyps, V. Gypsum. Gypsum, 3 Molybdenum oxide, 284. smphide, 233. Molybdite, 284. Moljy bdomenite, 432. Molysite, 261. Monazite, 368; 432. Mondstein, v. Moonstone. Monetite, 432. Monimolite, 370. Monite. 4;j2. Monrolite, 332. Montanite, 397. Montebrasite, 370; 420. Monticellite, 300. Montmartite, v. Gj^jsum. Montmorillonite, 349. Moonstone, 323, 324, 325. Mordenite, 432. Morenosite, 395. Moroxite, 365. Mosandrite, 309. Mottramite, 374. Mountain cork, 297. leather, 297. Muckite, 435. Muroraontite, 308. Muscovite, 313. Miisenite, v. Siegenite. Nadeleisenstein, 280. Nadelcrz, 254. Nadelzeolith, 342. Nadorite, 370. Nagyagite. 249; 433. Naiiia(|ualite, 282. Nantokite, 200. Naphtha, 413. Naphthaline, 414. GENERAL INDEX. 533 Natrolite, 342; 432. Natron, 409. Natronborocalcite, 381. Nauniannite, 235. Needle ore, v. Aikinite. Nemalite, 282. Neochrysolite. 423. Neocyanite, 432. Neotocite, 354. Nepheline, NejAelite, 816. Nephrite, 297, 432. Neudorfite, 435. Newbcryite, 432. Newjanskite, 224. Newportite, 358. Niccolite, 242. Nickel antimonide, 243, 247. arsenate, 372. arsenide. 242; 246. carbonate, 410. oxide, 267. silicate, 351, 427. sulphate, 395. sulphide, 241. telluride, 249. Nickel glance, v. Gersdorffite. Nickelarsenikglanz, 246. Nickelarsenikkies, 246. Nickelbluthe, 372. Nickel-Gymnite, 351. Nickelkies, 241. Nickelsmaragd, 410. Niobite, 360. Nitre. 379. Nitrobarite, 438. Nitrocaleite, 379. Nitroglauberite, 379. Nitromagnesite, 379. Nocerine, Nocerite, 488. Nohlite, 362. Nontronite, 850. Nosean, Nosite, 818. Noumeaite, Noumeite, 351. Nuttalite, v. Wernerite. Ochre, red, 269. Octahedrite, 277; 438. CEUacherite, 354. Okenite, 338. Oldhamite, 235. Oligoelase, 328. Olivenite, 373. Olivine, 300. Onofrite, 433. Ontariolite, 435. Onyx, 287. Oolite, 400. Opal, 288. Ophiolite, 350, 402. Orangite. 340. Orpiinent. 231 ; 433. Orthite, 308; 433. Orthoclase, 325; 438. Oryzite, 429. Osmiridium, 224. Osteolite, 365. Ottrelite, 358; 433. Ouvarovite, 304. Owenite, 858. Oxamniite, 483. Ozarkite, 342. Ozocerite, Ozokerit, 414; 433. Pachnolite, 265; 438. Pagodite, 349, 352. Paisbergite, 294. Palagonite, 353. Palladiiun, Native, 224. Pandermite, 434. Parachlorite, 436. Paraffin, 413. Paragonite, 354. Parankerite, 402. Paranthitc, 316. Para.site, v. Boracite. Parastilbite, 426. Parathorite, 340. Pargasite, 297. Parisitc, 408. Parophite, 353. Pattersonitc, 358. Pealite, 289. Pearl -mica, v. Margarite. Pearl-spar, 401. Pechkohle, 417. Pechopal, 2b9. Peckhamite, 433. Pectolite, 337; 433. Peganite, 378. Pegraatolite. v. Orthoclase. Pelagite, 433. Pelhamite, 355. Pencatite, 410. Pennine, Peiininite, 355. Penwithite, 433. Percylite, 262. Pcriclase, Perielasite, 267. Peridot, 300, 330. Perikline, I'eriklin, 324. Peristerite, 324. Perlglimnier, 357. Perthite, 826. Perofskite, 270; 483. Perowskit, 270. Petal ite, 295; 433. Petroleum, 413. Petzite, 2:19. Phacolite, 344. Phffiactinito. 420. Pharmacol ite, 370. Pharmacosiderite, 376; 433. Phenacite, Phenakit; 301; 433. Phengite, 431. Philadelphite, 439. Phillipitc, 397. Phillipsite, 345; 433. Phlogopite, 312. Phoenicochroitc, 386. Pholerite. 352. Phosgenite, 408. Phospiiocerite, 364. Phosphochalcite, 374. Phos|)hocliromite, 386. Phosphorite, 365. Phosphuranvlite, 434. PhylUte, 358. Physalite, 338. Ph'ytoeollite, 425. Piauzitc, 416, , Picite, 431. Pickeringite, 395 ; 4C4. Picotite, 271. Picranalcite, 420. Picroalhimogcne, 434. Picrolite, 351. Picromerite, 394. Picropharmacolitc, 371. Pictito, 336. Piedmontite, 308. Pihlite, 849. Pilarite, 423. Pilinite, 344. Pilolite, 434. Piraelite, 351. Pinite, 352. Pisanite, 395. Pisolite, 400. Pistacite, Pistazit, 307. Pistomesite, 403. Pitchblende, 274. Pittasphalt, 413. Pitticite, Pittizit, 379. Plagiocitrite, 434. Plagioclase, 319. Plagionite, 251. Plasma, 286. Plaster of Paris, 393. Platinum, Native, 223; 434. Platiniridium, 224. Pleonaste, v. Spinel. Plumbago, 230. Plumballophane, 341. Plumbogummite, 377. Plumbomanganite, 4o4. Plumbostannite. 434. Plumbostib, v. Boulangerite, Polianite, 278. Pollucite, Pollux, 299. Polyargitc, 353. Polyargyrite, 257. Polybasite, 257. Polycrase, 362. Polychroilite, 353. Polydvmite, 434. PolVhalite, 393; 434. Polymienite, 362. Poonahlite, 343. Porcellophite, 851. Posepnyte, 435. Potassium chloride, 260. chromate (?), 437. 534: GENERAL INDEX. Potassium nitrate, 379. silicate, 31:J, 325. sulpliate, 390. Potash = Potassium oxide, V. Potassium. Prase, 286. Prasine, 374. Praseolite, 353. Predazzite, 410. Pregattite, 354. Prehnite, 340. Prieeite, 382; 434. ProclilArite, 357. Proidonite, 264. Prosopite, 265. Protobastite, 290. Protoclilorite, 436. Protovenniculite, 439. Proustite, 253. Prussian blue, Native, 372. Przibramite, 2;J8, 28U. Pseudobrookite, 434. Pscudocotunnite, 261. Pseudomalachite, 374. Pseudonatrolite, 434. Pseudophite, 356. Psilomelane, 2S2 ; 434. Psittacinite, 374. Pucherite, 367. Purijle copper, 237. Pvcnite, v. Topaz. Pyrallolite, 348. Pyrargillite, 353. Pyragj'rite, 252. Pyreneite, 304. Pyrgom, 293; 434. Pyrite, 243. Pyi'ites, Arsenical, 247. Auriferous, 220. Capillary, 241. Cockscomb, 247. Copper, 244. Iron, 243. Magnetic, 241. Radiated. 247. Spear, 247. White iron, 247. Pvrochlore, 359. Pyrochroite, 282. Pyroconite, 265. Pyrolusite, 278; 434. Pyroinorphite, 366. Pyrope, 303. Pyrophosphorite, 434. Pyrophyllite, 349. Pyi'opissite, 414. Pyroretinite, 415. Pyrosclerite, 355. Pyrosmalite, 340. Pyrostilpnite, 253. Pyroxene, 292. Pvrrhite, 359. Pvri-hosiderite, 280. Pyrrhotite, 241 ; 434. Quartz, 284; 434. Quecksilberbranderz, 414. Quecksilberhornerz, 260. Quicksilver, 224. Riidelerz, 253. Radiated Pyrites, 247. Rairaondite, 395. Ralstonite, 265, 435. Randite, 435. Ratofkite, 263. Rauite, 342. Rauniite, 353. Realgar, 231. Red copper ore, 266. hematite, 209. iron ore, 269. ochre, 269. silver ore, 252, 253. zinc ore, 266. Reddingite, 435. Refdanskite, 351. Rcichardtite, 426. Reinite, 4 5. Reissite. 426. Remingtonite, 410. Rensselaerite, 348. Resanite, 339. Resin, Mineral, 415, 435. Restormelite, 353. Retinalite, 351. Retinite, 415. Reussinite, 415. Rhabdophane, 435. Rhajtizite, 332. Rhagite, 377. Rhodizite, 435. Rhodochrosite, 403; 435. Rhodonite, 294. Rhomb-spar, 401. Rhyacolite, 326. Rionite, 256. Ripidolite, 356. Rittingerite, 252. Rivotite, 370. Rock cork, v. Hornblende, crystal, 286. meal, 401. milk, 400. salt, 259. Roemerite, 395. Roepperite, 300. Roesslerite, 371. Rogenstein, 400. Rogers! te, 435. Romeine, Romeite, 370. Roscoelitc, 367; 435 Rose quartz, 286. Roselite, 372: 435. Rosterite, 420. Rosthornite, 415. Rosite, 353. Rothblcierz, 385. Rotheisenerz, 268. Rothgiiltigerz, 252, 253. Rothkupiererz, 266. Rothnickelkies, 242. Rothoffite, 303. Rothzinkerz, 266. Rubellite, 330. Rubislite, 435. Ruby, Spinel, Almandine,271 Oriental, 268. Ruby-blende, v. Pyrargyrite. Ruby silver. 252. 253. Rutherfordite, 362. Rutile. 276; 435. Ryacolite, v. Rhyacolite. Sahlite, 293. Sal ammoniac, 260. Salmiak. 200. Salt, Common, 259. Samarskite, 301 ; 435. Sammetblende, 280. Sanidin, 325. Saponite, 352. Sapphii-e, 208; 330. Sarawakite, 435. Sarcolite, 316. Sarcopside, 369. Sard, 287. Sardonyx, 287. Sartorite, 250. Sassolite, Sassolin, 380. Satin-spar, 393, 400, 405. Saussurite, 309. Savite, v. Natrolite. Scapolite Group, 315; 435. Schaumspath, 400. Scheelite, 384. Scheereite, 413. Schieferspath, 400. Schilfglaserz, 252. Schiller-spar, 351. Schirmerite, 251. Schmirgel, 2g8. Schneebergite, 435. Schoi-lomite, 337; 435, Schraufite. 415. Schreibersite, 242. Sehrifterz, Schrift-tellur, 24a Schrockingerite, 412. Schuchardtite, 436. Schuppenstein, 415. Schwaitzembergite, 262. Schwarzkupfererz, 267. Schwatzite, 255. Sch\veiVlkies, 243. Schwcrspath, 387. Scleretinite, 415. Scleroclase, 250. Scolccite, Scolezite, 343. Scored ite, 375. Seobachite, 344. Selcnblei, 236. Selenite, 393. Selenquecksilber, 237. I GENERAL INDEX. 535 Sellaite, 264. Semelinc, 335. Serascyite, 436. Senarmontite, 284; 486. Sepiolito, 349; 436. Serpentine, 350; 436. Serpierite, 436. Seybertite, 358. Shepardite, 242. Siderazot, 436. Siderite, 403. Sideronatrite, 436. Siderophyllite, 431. Siegburgite, 415. Siegenite, 245. Silaonite, 233: 428. Sill)eranialgam, 225. Silberglanz, 2-)5. Silbcrhoruerz, 260. Silberkupferglanz, 240. Silberwisnmthglanz, 420. Silex. V. Quartz. Silicifled wood, 286. Siliceous sinter, 287, 289. Siliciophite, 4o6. Silicoborocaleite, 382. Sillimanite, 331. Silver, 22:1 Antimonial, 234. Bismuth, 420. Horn, 260. Native, 223. Kuby, 252, 253. Vitreous, 235. Silver antimonide, 234. chloride, 260. bromide. 260. iodide, 260. selenide, 235. sulph-antimonite, 250, 2.-)2, 256. 257. sulph-arsenite, 253. sulphide, 235, 239. sulpho-bismuthite,420. telluride, 238;248,437 Silver glance, 235. Siraonyite, 394. Sinter, Siliceous, 287, 289. Sipylite. 436. Sismondine, 358. Sissei-skite, 224. Skapolith, v. Scapolite. Skleroklas, v. Sartorite. Skolezit, V. Scoleeite. Skutterudite, 246. Smaltine, Smaltite, 245; 436. Smaragdite, 297. Smectite, 349. Smithsonite, 404. Soapstone, 348. Soda = Sodium oxide, v. So- dium. Soda nitre, 381. Sodalite, 317. Sodium borate, 381. carbonate, 408, 409. chloride, 259. fluoride, 264. nitrate, 379. silicate, 323, 342. sulphate, 390, 391, 392. Sommite, 316. Sonnenstein, v. Sunstone. Sonomaite, 434. Spargelstein, 365. Spathic iron, 403. Spathiopyrite, 246. Spear pvrites, 247. Speckstein, 348, 352. Specular iron, 268. Speerkies, 247. Spessartite, 304. Speiskobalt, 245. Sphferocobaltite, 436. Sphaerosiderite, 403. Sphferostilbite, 346. Sphalerite, 237; 436. Sphene, 335. Spiauterite, 242. Spinel, 271. Spinthere, 335. Spodiosite, 430. Spoduraene, 295; 436. Sprodglaserz, 256. Sprudelstein, 405. Staffelite, v. Phosphorite. Stalactite, 400. Stalagmite, 400. Stanekite, 415. Stannite, 245. Staurolite, Staurotide, 336 ; 437. Steatite, 348. Steeleite, 432. Steinkohle, 417. Steinmark, 352. Steinol, 413. Steinsalz, 259. Stephanite, 256. Sterlingite, 354. Sternbergite, 240; 437. Stibianite, 437. Stibieonite, 437. Stibioferrite, 370. Stibnite, 232; 437. Stilbite, 346, 437; 347. Stilpnomelane, 349. Stolzite, 384. Strahlerz, 374. Strahlkies, 247. Strahlstein, 297. Strahlzeolith, v. Stilbite. Strengite, 437. Strigovite, 357. Stromeyerite, 240. Strontianite, 406; 437. Strontium carbonate, 406. Strontium sulphate, 388. Struvite, 371. Stuzite, 437. Stvlotvp, Stylotypite, 254 Siibdelessite, 425. Suceinellite, 415. Succinite, 415. Sulphur, Native, 228. Sunstone, 323, 325. Susannite, 391. Sussexite, 380. Svlvanite, 248. Sylvine, Sylvite, 260. Svngenite, 394. Szaboite, 437. Szaibelvite, 380. Szmikite, 437. Tabergite, 356. Tabular spar, 291. Tachhvdrite, 261. Tafelspath, 291. Tagilite, 373. Talc, :!48. Talktriplite, 437. Tallingite, 262. Tantalite, 359; 437. Tapalpite, 239. Tapiolite, 361. Tarapacaite, 437. Tasmanite, 415. Taznite, 437. Tellur, Gediegen, 227. Tellurite, 437. Tellurium, Bismuthic, 233. Foliated, 249. Graphic, 248. Native, 227; 437. Tellurium oxide, 437. Tellursilber, 238. Tellurwismuth, 233. Tengerite, 410. Tennantite, 256; 438. Tenorite, 267; 438. Tephroite, 300. Tequesquite, 438. Tequixquitl, 438. Tesseralkies, 246. Tetradymite, 233. Tetrahedrite, 255; 438. Thaumasite, 438. Thenardite, 390; 438. Thinolite, 438. Thomsenolite, 265; 438. Thomsonite, 342; 438. Thorite, 340; 438. Thulite, 309. Thuringite, 358. Tiemannite, 237. Tile ore, 266. Tin, Native, 226. Tin ore. Tin stone, 275. oxide, 275. pyrites, v. Stannite. 536 GENERAL INDEX. Tin sulphide, 345. Tinktil, 381. Titaneisen, 309. Titanic iron, 369. Titanite, 335; 438. Titanium oxide, 370; 376, 377. Titanolivine, 423. Titanomorphite, 438. Tiza, V. Ulexite. Tobernioiite, 428. Tocornalite, 3G0. Topaz, ;!33 ; 438. False. 386. Topazolitc, 304. Torbanite, 415, 418; 438. Torbernite, Torberite, 378. Totaie:ite. 436. Tourmaline, 329, 438. Travertine, 400. Tremolite, 297. Tricliite. 110. Tricla-site, 353. Tridvniite, 288; 439. Tripiivlite, Triphyline, 369; 439. Triplite, 369. Trii)loidite, 439. Tripolite, 289. Trippkcite, 439. Tritoehorite, 426. Tritomite, 340. Trogc-rite, 379. Troilite, 242. Trona.408. Troostite, 301. Tscheflfkinite, 336. Tschermakite, 323. Tscherniigite, 395. Tufa, Calcareous, 400. Tungsten oxide, 284. Tungstite, 284. Turgite, 279. Turmalin, 329. Turnerite, 368, 433. Turcjuois, 377. Tvrite, 363. Tyrolite, 374. Tysonite, 439. Uloxite, 381. Ullmannite, 347. Ultramarine, 318. Unionite, 309. Uraconise, Uraconite, 397. Uranglimmer, 378, 379; 439. Uranin, Uraninite, 374. LTranite, 378, 379. Urinium arsenate, 379. carbonate, 413,439. oxide, 274. phosphate, 378, 379, 434. silicate, 341. sulphate, 397. Urankalk, 413. Uranmica, 378, 379. Uranochalcite, 397. Uranocircite, 439. Uranophane, 341. Uranospinite, 379. Uranotantalite, 361. Uranothallite, 439. Uranothorite, 438. Uranotilc, 341; 439. Uianpecherz, 374. Urao, 409. Urpethite, 413. Urusite, 436. Urvolgyite, 438. Uwarowit, 304. Vaalite, 355. Valentinite, 284. Vanadinite, 367; 489. Variscite, 439. Vauqueline, Vauquelinite, 386. Venasquite, 433. Venerite, 439. Verd-antique, 350. Vermiculite. 355 ; 439. Vesbine, 439. Vesuvianite, 305, 440. Veszelyite, 373, 440. Victor'ite, 290. Vietinghofite, 435. Villarsite, 340. Vitreous copper, 239. silver, 335. Vitriol. Blue, 394. Vivianite, 371. Voglianite, 397. Voglite, 413. Volknerite, 383. Volborthite, 374. Voltaite, 395. Vorhauserite, 351. Vreckite, 422. Vulpinite, 389. Wad, 383, 440. Wagnerite, 368; 440. Walchowite, 415. Walkerite, 433. Walpurgite, 379, 440. Waluewite, 440. Wapplerite, 371. Warringtonite, 396. Warwickite, 383. Wattevillite, 440. Wavellite, 376. Websterite. i'. Aluminite. Wehrlite, 333. Weissbleierz, 407. Weissite, 353. Weisspicssglaserz, 384. Wernerite, 316., Werthemanite. 396. Westanite, 332. Wheelerite, 415. Wheel-ore, 253. Whewellite, 413. Whitnevite, 235. Wichtine, Wichtislte, 399. Willcoxite, 358. Willemite. 301, Williamsite, 351. Wilsonite, 353. Winklerite, 372. Winkworthite, 382. ^^'iserine, 277. 364. Wismuth, Gediegen, 227. Wismuthglanz, 233. Wismuthocker, 284. Wismuthspath, 413. Witherite, 406. Wittichenite, 254. Wocheinite, 281. Wohlerite, 300. Wolfachite, 247. Wolfram. 383. Wolframite, 383. Wollastonite, 291. Wollongongite, 416; 4381 Wood-opal, 289. Wood tin, 275. Wcodwardite, 397. Worthite, 332. Wulfenite, 384; 440. Wiirfelerz, 376. Wurtzite, 243, 426. Xantholite, 437. Xanthophyllite, 358; 440. Xanthosiderite, 281. Xenotime, 364; 440. Xyloretinite, 415. Yenite, 309. Youngite, 440. Yttergranat, 303. Ytterspath, 364. Yttrium phosphate, 364. Yttroeerite, 364. Yttrogummite, 433. Yttrotantalite, 3G1, 863. Yttrotitanite,386. Zaratite, 410. Zeolite section, 342, Zepharovichite, 376. Zeunerite, 379. Ziegelerz, 266. Zietrisikite, 414. Zinc, Native, 226. Zinc aluminate. 273. arsenate, 373. blende, 237. bloom, V. Ilydrozincite, carbonate, 404, 410. GENERAL INDEX. 537 Zinc ore. Red, 266. oxide, 206, 373. silicate, 301, 339. sulphate, 395, 440. sulphide, 237, 242. Zincaluminite, 440. Zincite, 266. Zinkbliithe, 410. Zinkenite, 250. Zinkspath. 404. Zinnerz, Zinnstein, 275. Zinnkies, 245. Zinnober. 240. Zippeite. 397. Zircon, 304; 440. Zoisite, 308. Zoblitzite, 351. Zonofhlorite, 340. Zorurite. 237. 1 Zinnwaldite, v. Lepidolite. Zwieselite, 369. \ \^