THE UNIVERSITY 
 
 OF ILLINOIS 
 
 LIBRARY 
 
 549 
 
 Dl9r3 
 
Return this book on or before the 
 Latest Date stamped below. 
 
 University of Illinois Library 
 
 ^ u u C 
 
 9 
 
 
 L161 — H41 
 
THE UNIVERSITY 
 
 OF ILLINOIS 
 
 LIBRARY 
 
 549 
 
 D\9r3 
 
* / tf/S 
 
'1 
 
 f 
 
 
 
THE LIBRARY 
 
 Of THE 
 
 UNIVERSITY Of ILLINOIS 
 
John, fVeole, Mph JJdtterh 1840 . 
 
RUDIMENTARY TREATISE 
 
 ON 
 
 MINERALOGY 
 
 THIRD EDITION: 
 
 TO WHICH IS ADDED, 
 
 1 i'rrntisE m Units nt ffljnmi iggrigntrs, 
 
 BY JAMES DANA, A.M., 
 
 OF THE UNITED STATES. 
 
 TWO PARTS, COMPLETE IN ONE VOLUME. 
 
 With Illustrations. 
 
 LONDON: 
 
 JOHN WE ALE, 59, HIGH HOLBOllN. 
 1856. 
 
LONDON ’ 
 
 , K1NG ? S HEAD COURT, GOUGH SQUARE. 
 
 PRINTED BY JOHN WE ALE, 
 
r V f 
 
 T . 
 
 sj 
 
 A IDV3n-3 
 
 . v i , / ( 
 
 * ADVERTISEMENT. 
 
 & 
 
 4- 
 
 In the following pages the Student and Amateur in 
 Natural Science are furnished with some information 
 about most of the mineral substances that are met 
 with, either on the surface of the earth, in rocks, or in 
 mines. There are still many others in Nature, besides 
 those herein described ; some of w T hich are rare ; several 
 have never been analyzed ; others only partially ex- 
 amined, and their proper situation hardly established ; 
 and the majority of them are unimportant, especially 
 to one little acquainted with the subject. 
 
 In accordance with the natural systems which prevail 
 in other branches of Natural History, the classification 
 adopted is chemical, and is nearly that of Beudant ; a 
 system which recommends itself by its simplicity. 
 
 A third edition of this useful work being called for 
 by the extensive sale of the first and second editions, 
 I have added in this edition Mr. Dana’s admirable 
 Treatise on Rocks. 
 
 November 1 st, 1855. 
 
 J. W. 
 

 ' s- 
 
 ' 
 
 
THE LIBRARY 
 
 OF THE 
 
 UNIVERSITY Of ILLINOIS 
 
n 
 
 u 
 
 22 
 
 X?5| 
 
 
 JoJuvWeaU.59 . EiqhHolborrv I84&. 
 
 J.W.Louoy/c. 
 
J TrZowv. Sr 
 
 John. Tft-aZe.59 High JSolbam. 
 
J. T1\Zo (/Vi .Sr., 
 
MINERALOGY. 
 
 L. Natural History is a science which consists of many 
 anches ; one, which treats of animals, is called Zoology ; 
 other, Botany, teaches the structure and properties of 
 ants ; the third, which makes us acquainted with the inor- 
 mic portions of our planet, namely, stones or minerals, is 
 lied Mineralogy ; and if, at first sight, it should appear less 
 tractive or less useful than the other two branches, a very 
 tie consideration will prove that it is of equal importance to 
 ankind, and contributes materially to their comfort, wealth, 
 id luxury. From materials found in the interior of the earth 
 e erect our dwellings, we supply ourselves with fuel, we con- 
 ruct numberless tools and machines, and, finally, we obtain 
 ir most brilliant ornaments. 
 
 Some knowledge of many of these substances must have 
 een possessed at a very remote period. The most ancient 
 ations of whom we have any record manufactured arms, and 
 rnaments of gold and silver. The Romans, who made great 
 nprovements in the arts of civilisation, greatly enlarged this 
 nowledge ; bringing to light many substances previously 
 nknown, and employing them for useful or ornamental pur- 
 poses : they were acquainted with several of the precious 
 tones, and, with the exception of the diamond, succeeded in 
 utting and engraving on them. 
 
 The elder Pliny, a man of enquiring mind and unwearied 
 liligence in the pursuit of knowledge, collected, from every 
 source within his reach, accounts of all the natural productions 
 
 B 
 
2 
 
 MINERALOGY. 
 
 that were then known, or of which any description existed in 
 his time ; and he added to these his own observation on such 
 as he had actually examined. It is much to be regretted that 
 the latter were not more numerous ; for he too often copied, 
 without enquiry, the descriptions he met with ; and has trans- 
 mitted to us a vast number of inaccuracies and absurdities, 
 such as accounts of the magical properties of certain stones, 
 plants, and animals, and charms by which particular diseases 
 might be cured. 
 
 As civilisation extended, and the arts of life advanced, a 
 greater number of useful minerals became known : improve- 
 ments in machinery and practical science led to greater facility 
 in the working of mines, metals were more sought after, new 
 ones were discovered, and new and rich ores of those already 
 known were found to exist, which had formerly been thrown 1 
 aside as valueless, from ignorance of their nature. Mineralogy 
 now became a subject of importance, and much attention was 
 paid to it : but it still retained somewhat of a vague and 
 unsatisfactory character, from want of knowledge of the prin- 
 ciples on which it ought to be based. Chemistry, indeed, 
 lent its aid in the analysis of minerals : but it was before 
 chemistry itself had been raised to the state of an exact 
 science by the wonderful and beautiful law of definite propor - 
 tionSy — a law which pervades all chemical combinations, whe- 
 ther natural compounds or the result of operations in our 
 laboratories. This law assists us in ascertaining with precision 
 the composition of mineral substances, and consequently in 
 identifying mineral species, and giving them their true place 
 in a scientific classification. 
 
 The want of some knowledge of the real nature of stones, 
 which even a slight acquaintance with mineralogy would fur- 
 nish, has occasioned to many persons, within a comparatively 
 recent period, very ruinous loss ; whilst others have rapidly 
 acquired a fortune from profiting, under similar circumstances, 
 by opportunities that had been unseen or totally neglected. 
 It is not above fifty years since a man found in Shropshire a 
 
UNORGANISED BODIES. 
 
 3 
 
 considerable vein of sulphate of baryta, which, in consequence 
 of its weight, he mistook for white lead ore, and he erected a 
 smelting-house and furnaces for the purpose of reducing it to 
 a metallic state. Another person in the same county, having 
 met with some mica in the form of small silvery scales or 
 spangles, was persuaded that he had found a silver mine, and 
 ruined himself in attempts to obtain the silver. 
 
 Among many other unfortunate adventures which have 
 arisen from ignorance of mineralogy, may be mentioned that 
 of a poor man, who was persuaded* to lay out a hundred 
 pounds, nearly the whole of some years’ economy, in the 
 purchase of a few pieces of white topaz, under the idea that 
 they were diamonds. But independently of the utility of this 
 science, any one who studies natural history for his amuse- 
 ment , will be richly rewarded by the wonders and the beauties 
 displayed in the mineral kingdom. 
 
 § 2. The bodies which are the objects of study to the 
 mineralogist, comprise the earthy, metallic, saline, and other 
 substances which compose our earth ; that is to say, the un- 
 organised part of the creation. 
 
 To understand clearly what is meant by the term unor- 
 ganised, let us remember that an animal and a plant are said 
 to be organised , because they consist of several different parts, 
 all varying in their form, their position, and their functions, 
 yet all equally necessary to form a perfect animal or a perfect 
 plant; so that to remove any one of them, would be to destroy, 
 or at least to render imperfect, the body to which it belongs. 
 These parts are called organs ; in animals we find a stomach to 
 digest the food they convey to it, and by means of which they 
 are nourished and have life ; nerves and muscles for sensation 
 and motion : in plants we observe a root to fix them to the 
 ground, and absorb nourishment from it, and vessels for the 
 circulation of the sap . 
 
 But in a mineral, in its most perfect state, all the parts 
 exactly resemble each other ; so that, by breaking it, we 
 diminish it in size without destroying its existenqe or its com- 
 
 b 2 
 
4 
 
 CHARACTERS OF MINERALS. 
 
 pleteness. Take, for example, a flint pebble, or a fragment of 
 limestone from a quarry, and break it : we shall find that each 
 substance is of the same texture and composition throughout. 
 It is true that we may also take up a stone, or break off a 
 piece of rock, which has not this homogeneous structure ; as, 
 for instance, a granite paving stone : but granite is an aggre- 
 gate rock, which consists essentially of three simple minerals, 
 each of which may plainly be distinguished on inspection ; and 
 mineralogy teaches us to recognise in it, 1st, quartz, which 
 usually appears in greyish semi-transparent grains, of a some- 
 what glassy appearance ; 2nd, felspar, of a reddish or yellow- 
 ish white, and opake ; 3rd, mica, in small scales which have a 
 shining and somewhat metallic lustre. 
 
 The present work is designed to afford such information in 
 mineralogy as may assist any one to ascertain the names and 
 properties of minerals either in studying this branch of science 
 at home, or as a means of increasing the interest he may feel 
 in collecting during his travels. 
 
 It is true that the essential difference of minerals consists in 
 their composition ; but it is not, therefore, necessary to subject 
 every mineral to chemical analysis in order to know something 
 of its nature. The difference of composition is manifested in 
 difference of form, structure, colour, weight, hardness, trans- 
 parency, &c. ; and an acquaintance with these and some other 
 properties or characters will, in most cases, enable us to recog- 
 nise a mineral species ; and to know of what elementary sub- 
 stances it principally consists. With these, which are called 
 the external and physical characters , we shall endeavour to 
 make the student acquainted. 
 
 But it sometimes happens that we meet with a specimen in 
 which these characters are not clearly marked ; or some of 
 them may have a great resemblance to those of another spe- 
 cies : in such cases we may derive great assistance from an 
 examination of some of the chemical characters , by means of 
 acids and the action of the blowpipe, which have a very 
 different effect on different species. 
 
CRYSTALLINE FORMS. 
 
 0 
 
 § 3. Among the characters of minerals, the most impor- 
 tant, because the most constant and obvious, is their regular 
 or crystalline form . 
 
 The regular figures of rock crystal and the diamond, 
 attracted the attention of the ancients, and are mentioned by 
 Pliny : but they were considered, till a much later period, only 
 as curious accidental circumstances. Linnaeus was the first 
 who suggested that they must be the result of constant pro- 
 perties, and might be important in the study of minerals : but 
 he appears to have been acquainted with very few, and to have 
 neglected the subject. 
 
 Rom de Lisle, a French mineralogist, collected a vast num- 
 ber of crystals of different substances, examined them with 
 care, and, by comparing together those of the same species, 
 found, not only that certain angles were invariable, but that 
 figures the most unlike had a relation to each other ; that they 
 were derived from some fundamental form, altered by the 
 solid angles or edges appearing to be removed, and replaced 
 by one or more planes, sometimes small, sometimes so large 
 as to efface those of the original solid, and to produce another. 
 
 § 4. As an example of this relation, let us compare some of 
 the crystals which are common to Galena (PI. I.). Fig. 1 is 
 a perfect cube : in fig. 2 the solid angles appear to be removed 
 and to be replaced by small triangular planes : in fig. 3 the 
 triangular planes are increased so as to meet each other : in 
 fig. 4 they are still larger, and intersect each other. The 
 crystal now assumes the appearance of an octahedron of which 
 the solid angles are replaced by small square planes. When 
 the triangular faces increase in size, to the exclusion of the 
 square ones, we have a complete and regular octahedron, 
 fig. 5. 
 
 If the edges instead of the angles of the cube be replaced by 
 planes inclining equally on the adjoining faces, fig. 8, they 
 will, if increased, produce a dodecahedron with rhombic faces 
 (fig. 9). The same form will be obtained if the planes which 
 replace the edges of the octahedron, as in fig. 10, be enlarged 
 
6 
 
 CRYSTALLOGRAPHY. 
 
 till the original ones disappear. In this figure, the solid 
 angles are of two kinds : six, which coincide witji those of the 
 inscribed octahedron, are formed by the meeting of four acute 
 plane angles ; the remaining eight, which agree with the angles 
 of an inscribed cube, are composed of three obtuse plane 
 angles. 
 
 This connection between solids of very different form will 
 be better understood if the student will take a cubic crystal of 
 fluorspar, and with a knife, properly placed, and a sharp blow 
 from a hammer, detach from each solid angle a small three- 
 sided pyramid. The faces so produced will always he equi- 
 lateral, and the solid obtained will be similar to fig. 2 or 3, 
 PI. I. 
 
 If only four alternate angles of the cube be 
 removed (in the direction of the dotted lines 
 No. 1), or, which is the same thing, if four 
 alternate faces of the octahedron be enlarged 
 till the others disappear, he will obtain (fig. 6.) 
 the regular tetrahedron. 
 
 The modification represented in fig. 12, PI. I., a bevelled 
 cube, if carried to its greatest extent, would produce a solid 
 of 24 faces, whieh is not uncommon in fluorspar : but it often 
 happens that only half of the modifying planes occur, and that 
 they are then placed alternately on the similar edges (as in 
 the last example they were plaeed on the alternate angles) : 
 the cube thus modified would be represented by fig. 13, 
 and if the bevelling planes were enlarged till they effaced 
 those of the cube, we should have a pentagonal dodecahedron, 
 fig. 14. 
 
 The same planes occur on alternate angles of the octahe- 
 dron (fig. 15), and when they are increased, the two modi- 
 fications together produce the icosahedron, fig. 16, a solid 
 of 20 faces. 
 
 The angles of the cube are sometimes replaced by three 
 planes, as in fig. 17, which, if enlarged, would finally produce 
 a solid of 24 faces, called a trapezohedron, fig. 18, a form often 
 
 No. I. 
 
CRYSTALLOGRAPHY. 
 
 7 
 
 met with in the garnet. It will easily be seen that the same 
 form is derivable from an octahedron. 
 
 § 5. In this manner, the multitude of crystalline forms at 
 present known, and which amount probably to some thou- 
 sands, may be referred to a very small number of simple 
 figures, each of which is the base or type of a group. The 
 first of these groups consists of the solids we have enumerated, 
 which may all be referred either to the cube or the octahe- 
 dron ; besides an indefinite number which may be conceived 
 to arise from the replacement of angles and edges by addi- 
 tional planes, and various combinations of those above men- 
 tioned. 
 
 The simple forms from which those of the second series are 
 derived, are the hexagonal A No. 2. A No. 3. 
 
 prism and the rhombohe- 
 dron. The latter solid is of 
 two kinds ; No. 2 represents 
 an obtuse, No. 3 an acute 
 rhombohedron. They must 
 not be confounded with the 
 
 oblique rhombic prisms ; for ^ 
 
 the faces of a rhombohedron 
 
 are always exactly similar and equal : and it is represented in 
 a symmetrical position when the axis, A X, is vertical ; and all 
 the modifications to which it is liable take place symmetri- 
 cally with relation to this line, which passes through the sum- 
 mits of the rhombohedron. If the student examine a model 
 of this solid, he will see that these summits differ from the 
 other solid angles, (whicfli are termed lateral ,) being formed 
 by the meeting of three equal plane angles : in No. 2 these 
 are obtuse, in No. 3 acute. He will also distinguish the 
 terminal edges , t t t, which meet at the summits, from the 
 lateral edges which meet in the lateral angles. 
 
 Equilateral six-sided pyramids and triangular dodecahe- 
 drons of which the edges are alternately equal twelve- 
 sided prisms, either simple or united with some of these, 
 
8 
 
 CRYSTALLOGRAPHY. 
 
 and rhombohedrons of various angles, also belong to this 
 group. 
 
 The replacement of the terminal edges No. 4 produces a 
 rhombohedron more obtuse than the primary one No. 5, and 
 
 the replacement of the lateral edges gives the regular hex- 
 agonal prism No. 6 ; its bases resulting from the replacement 
 of the summits of the rhombohedron No. 7. 
 
 But if the lateral edges be replaced by two planes this modi- 
 
 No. 8. No. 9. No. 10. 
 
 fication, if continued so as to destroy the primary faces, would 
 produce a scalene dodecahedron No. 8 : that is to say, of 
 which the triangular planes have their sides unequal. 
 
 The double six-sided pyramid with equal faces No. 9, and 
 another hexagonal prism No. 10, arise from the replacement 
 of the lateral angles of the primary solid ; and it will be seen 
 that the lateral faces of this prism correspond in situation with 
 the edges of the one above described. 
 
 Among the crystals of calcspar, the student will find all 
 these modifications of the rhombohedron and very many 
 others. 
 
 The square prism (fig. 19) is the basis of a very symmetri- 
 
CRYSTALLOGRAPHY. 
 
 9 
 
 cal group, all the lateral faces being equal, and similarly 
 situated : for it is a general law in crystallization, that what- 
 ever secondary planes are found to replace any solid angle 
 or edge of a crystal, every similar angle or edge will be simi- 
 larly modified. In the cube, therefore, and all the simple 
 solids of that series, every edge and angle undergoes the same 
 alterations. 
 
 Various octahedrons, both acute and obtuse (figs. 20, 21), 
 prisms with eight, or twelve, or sixteen sides (figs. 23, 24), 
 and rhomboidal dodecahedrons, which, though symmetrical, are 
 not regular (fig. 22), belong to this type (figs. 19 to 24). 
 
 The crystals derived from a right prism with a rectangular 
 base, form a series which has less symmetry than these, be- 
 cause only the opposite faces, two and two, are equal ; and the 
 longer and shorter edges exhibit separate and sometimes very 
 different modifications : of these, four and four are equal, and 
 in all respects similarly situated, as marked in the diagram. 
 
 No. 11. No. 12. No. 13. 
 
 a b 
 
 b a 
 
 The second and third figures show the relation of the right 
 rhombic prism to this parallel op iped : in the one, by removing 
 the lateral edges of the rectangular prism, by planes parallel 
 to its diagonals, we obtain one with a rhombic base : and in 
 the same manner the rectangular prism may be obtained from 
 the rhombic one. Both are primary forms, and from them 
 are derived octahedrons with a rectangular or a rhombic base. 
 
 In the same manner, from an oblique prism with a rectan- 
 gular base, we derive a rhombic one, of which the axis . and 
 lateral faces will have the same inclination to the base ; these 
 are fundamental figures of the fifth series. The symmetry 
 
 b 5 
 
10 
 
 CRYSTALLOGRAPHY. 
 
 No. 14. 
 
 No. 15. 
 
 No. 16. 
 
 M 
 
 and equality of the edges and solid angles are indicated by a 
 repetition of the same let- 
 ters : the secondary forms, 
 which are the consequence 
 of their various modifica- 
 tions, will be noticed in the 
 description of such minerals 
 as have one or other for 
 
 their primary crystal. It should be observed, that if the 
 oblique prism with a rectangular base be 
 placed on one of its lateral faces, it may be 
 considered to be a right prism, with a rhom- 
 boidal base : by comparing the annexed dia- 
 gram No. 16 with the former one No. 15, 
 the identity of the two solids will be evident. 
 
 The last group has for its basis a parallelo- 
 piped which has the least possible symmetry ; an oblique 
 prism with an oblique angled parallelogram 
 for its base. No. 17. The only equality both 
 of sides and angles, in this solid, is in those 
 which are diagonally opposite. 
 
 The forms belonging to some of these 
 groups are common to several different sub- 
 stances, as for instance, the cubic series, 
 which includes the crystals of the native 
 metals, of galena, spinel ruby, fluorspar, and several others : 
 in the rhombohedral series we find the crystallizations of 
 calcspar, the beryl, phosphate of lime and of lead, red silver 
 ore, &c. 
 
 § 6. Crystals are found much more commonly in groups 
 than singly, and their modes of arrangement are very various. 
 Cubes are sometimes aggregated so as to form an octahedron, 
 as we see in fluorspar ; rhombohedrons are sometimes built 
 up into the form of a triangular dodecahedron, as in calcspar ; 
 prismatic crystals are very often united together at one ex- 
 tremity, forming a radiating mass with pointed terminations 
 
 No. 17. 
 
HEMITROPES DISTORTED CRYSTALS. 
 
 11 
 
 on the exterior part : this is the case with several kinds of 
 zeolite, amethyst, and many other substances. 
 
 § 7. But the most singular groups are those called macles 
 or hemitropeSy because they resemble a crystal which has been 
 cut in two, and of which one part has been turned half round 
 and re-united to the other. 
 
 Such a division and re-union, 
 has, of course, never taken 
 place ; a made consists in 
 reality of two crystals, united 
 by a corresponding face of 
 each, but placed inversely with 
 respect to each other, and which appear to have increased 
 after their union, by a continual addition of particles to each, 
 until the plane of junction is considerably extended. This 
 plane is sometimes parallel to two opposite faces of the pri- 
 mary crystal, as in the example of the regular octahedron : 
 sometimes diagonal, as in the oxyde of tin, felspar, and other 
 minerals. 
 
 § 8. In all these numerous forms, we find in the same 
 species, the same angles or inclinations of planes, however 
 irregular they may appear from the unequal size of the faces. 
 Distorted crystals of quartz are of very common occurrence, — 
 one face of the pyramid is often much enlarged at the expense 
 of the others ; yet the inclinations of the corresponding faces 
 in this and the regular hexagonal pyramids will be found to 
 be the same in both. 
 
 § 9. In order to ascertain the measure of these angles, 
 and thus establish the identity of a species, an instrument 
 called a Goniometer* is employed. There are several kinds, 
 but that invented by Dr. Wollaston is most generally used, 
 being simple in its construction, and easy of application. It 
 consists. No. 20, of a graduated circle A B, placed vertically, 
 the axis being hollow, in order to enclose an interior one 
 
 * From two Greek words, gonia an angle, and metreo I measure. 
 
12 
 
 GONIOMETER. 
 
 No. 20. 
 
 supporting a moveable apparatus C, which is turned by means 
 of the small circle b. In order to make use of it, the large 
 circle, which is divided twice into 180 degrees, must be placed 
 at zero (or 180 °), and 
 the crystal attached 
 with a little wax to a 
 small plate a , so that 
 the edge may be hori- 
 zontal, and as nearly 
 as possible in a line 
 with the axis of the 
 circle. 
 
 Place the instru- 
 ment on a firm table 
 before an open win- 
 dow, from which the 
 horizontal lines of some 
 building may be clear- 
 ly seen, such as the 
 ridge of the roof, the 
 rail of a balcony, &c. ; 
 let the plane of the circle be also, as nearly as possible, per- 
 pendicular to the plane of the building so viewed. 
 
 Placing the eye then very near, and somewhat above the 
 crystal, the inner axis is to be gently turned, until the reflec- 
 tion of one of these lines (the higher ones are generally the 
 best for the purpose,) is distinctly seen by reflection, on the 
 upper face of the crystal; and this movement is to be con- 
 tinued until the reflection appears to coincide with some other 
 horizontal line, seen by direct vision ; such as the lower edge 
 of the open window, or the edge of the table. If these two 
 lines correspond exactly, the face of the crystal is placed 
 horizontally ; if not, its position must be gently altered by 
 means of the jointed apparatus which supports it, or by turn- 
 ing the circle d . The same operation is to be repeated with 
 the second face ; and if its position requires to be corrected, 
 
MEASUREMENT OF ANGLES OF CRYSTALS. 
 
 13 
 
 the first face must be re-examined, lest its horizontally should 
 have been deranged. 
 
 Supposing the crystal to be now perfectly adjusted, and the 
 reflected line on the first face brought to coincide with a lower 
 one, the great circle must be turned by means of c (the crys- 
 tal being turned by the same motion,) until the same distant 
 line is reflected in the second face, and brought to correspond 
 with the same lower line. 
 
 We shall find the value of the angle sought indicated on 
 the graduated circle, which has turned through the space of 
 the supplementary angle ; but being graduated in a contrary 
 direction, the true angle is read off. 
 
 § 10. It will generally be found that the faces of small 
 crystals are more pefectly even than those of large ones ; 
 they are therefore, in every respect, better adapted for exa- 
 mination by the reflecting goniometer. But even in those 
 which appear the most perfect, a comparison of the angles of 
 several crystals, shows that they sometimes differ to a very 
 small extent , in consequence of slight depressions or elevations 
 on their surfaces. But in a great number of substances, 
 their natural structure affords us the means of ascertaining 
 the angles of the primary form with the greatest precision. 
 
 This structure, which is inherent in their nature, depending 
 on the arrangement of the minute particles of which they 
 consist, becomes perceptible by the manner in which they 
 divide or split when we break them. A slight blow on a 
 piece of calcspar will separate it into fragments which are 
 either rhombohedrons or parallelopipeds, of which the faces 
 meet at the same angles as the planes of the rhombohedron : 
 this solid is therefore, from its symmetry, considered to be the 
 primary form of its crystals. 
 
 If the blow be too slight to shatter the specimen, it will 
 often produce internal fissures, which are distinctly seen, in 
 consequence of the light they reflect, to be plane surfaces 
 parallel to the external ones : these are called planes of cleav- 
 age ; and calcspar is capable of this kind of division in three 
 
14 
 
 CLEAVAGE. 
 
 directions, with equal facility. Sulphate of baryta, also, has 
 three cleavages, which are parallel to the faces of a right 
 rhombic prism. In this case also, the regular solid obtained 
 by cleavage is considered to be the primary form of the 
 species, though in the latter instance, the same crystals might 
 be derived from (or referred to) a right prism w r ith a rectan- 
 gular base. 
 
 § 11. It w r ill be evident then, that the observation of crys- 
 talline structure, where it exists, is of the greatest importance 
 in mineralogy, not only as showing the relation between forms 
 the most dissimilar, but as affording ready proof of the identity 
 of a species, in circumstances where it would otherwise be 
 extremely difficult to distinguish it ; when, for instance, it is 
 disseminated in minute portions through some other mineral : 
 felspar, diallage, and some other substances frequently occur 
 in such a situation. 
 
 Some minerals, however, may be cleaved with much greater 
 ease in one or in two directions than in the third. Some yield 
 to cleavage in one direction only, as in the case of mica and 
 selenite. 
 
 § 12. Besides the regular and perfect crystallizations of 
 minerals, of which we have given an outline, the aggregation 
 of crystals more or less perfect gives rise to numerous con- 
 figurations, some of which are peculiar to certain species. In 
 some, the crystals are grouped into spheroidal masses, the 
 edges or points of the crystals appearing on the exterior of 
 the mass, as in blue carbonate of copper, iron pyrites, &c. 
 
 The slender prisms in which many substances crystallize are 
 often compressed together lengthwise, and form cylindroidal 
 or bacillar groups ; the crystals, even on the exterior, being 
 always deformed and their edges rounded. 
 
 The branched and leafy forms and moss-like aggregations, 
 so frequently met with in some of the native metals, consist of 
 more or less perfect crystals. When the crystals are very 
 minute and the branches of a more even thickness, they pre- 
 sent the form of coral. 
 
STALACTITES EXTERNAL FORM. 
 
 15 
 
 § 13. The stalactites which so often occur in caverns, 
 irregularly conical or cylindrical in their form, or incrusting 
 their walls, are produced by the deposition of minute particles, 
 generally calcareous, from water which percolates through 
 their roof or sides. When a small quantity of moisture arrives 
 at the inner surface of the roof, before a drop is formed suffi- 
 ciently large to fall by its own weight, a portion of it evapo- 
 rates, and a ring-shaped film of solid matter is left adhering to 
 the rock. Every succeeding drop increases the thickness of 
 this film, until at length a slender tube is formed, which is 
 constantly increased in thickness as well as in length. In 
 general the interior is quickly filled up, and becomes perfectly 
 solid : but sometimes the stalactites are hollow throughout a 
 great part of their length. When the water drops more 
 rapidly, a portion of it falls on the floor of the cave, depositing 
 there solid particles, which accumulate and produce masses 
 resembling moss, fungi, and cauliflowers, which are sometimes 
 called stalagmites. 
 
 § 14. Minerals, also, which do not crystallize, often assume 
 definite forms externally, which are characteristic and deserv- 
 ing of attention. In some the surface consists of portions of 
 spheres of different dimensions : when these are small, some- 
 what resembling a bunch of grapes closely pressed together, 
 the mass is termed botryoidal:* when the globular surfaces are 
 of larger dimensions, it is said to be mamillated :f calcedony 
 and malachite are good examples of these forms : and the no- 
 dules of iron pyrites, which exhibit a similar surface on a 
 smaller scale, are called reniform.\ 
 
 § 15. We have already remarked that in many substances 
 which crystallize, their regular or laminated structure becomes 
 visible on breaking them : but minerals which do not yield to 
 cleavage in any direction, or with difficulty and uncertainty, 
 break into indeterminate fragments : their form varying with 
 the texture of the mineral. In those which are crystalline 
 
 * From the Greek word hotrm } a cluster of grapes. 
 
 f Lat. mamma , the breast. J Lat. ren, a kidney. 
 
16 
 
 FRACTURE. 
 
 and may be termed vitreous, as Quartz and Beryl, the fracture 
 of the broken part is said to be conchoidal , a form which is 
 illustrated in the fragments of glass ; a still better example of 
 the conchoidal fracture is to be found in breaking a large flint 
 pebble ; the texture of flint is compact and even , and all 
 minerals possessing the same kind of structure or texture, 
 break in a similar manner. 
 
 In others, which are less hard and compact, the fracture 
 will be uneven or earthy. The native metals, if they do not 
 afford cleavages, have a hackly fracture, which may be observed 
 on breaking a piece of thick wire, or plate of metal. 
 
 The fibrous structure common to many species, arising from 
 an aggregation of delicate prisms, sometimes parallel, some- 
 times divergent or radiated, is also evident in the appearance 
 of the fracture. Hence the fresh fracture of a mineral makes 
 us somewhat acquainted with its structure, and should always 
 be remarked. 
 
 § 16. Among the optical characters of minerals, some are 
 not only very remarkable, but, like their crystalline forms, 
 they belong to the disposition of their particles, and are equally 
 constant in the same species. Of such kind are the phenomena 
 of refraction : other properties relating to light, such as the 
 colours and transparency of minerals, are in some species 
 characteristic ; but in others they are frequently varied by 
 accidental causes. 
 
 The property of double refraction possessed by many sub- 
 stances, is particularly evident in the transparent varieties of 
 calcspar, which have obtained from this circumstance the 
 name of doubly refracting spar. If a line traced on paper be 
 viewed through a fragment of this mineral, two lines will 
 appear ; and on turning the calcspar round, as it lies on it, 
 both images will move until they coincide ; and on turning it 
 still farther, one will seem to pass over the other. This is 
 because one portion of the light is refracted in the ordinary 
 manner, as we see in glass and water; the other portion, 
 called the extraordinary ray , is refracted in a different manner : 
 
DOUBLE REFRACTION. 
 
 17 
 
 and it is found that excepting those substances whose crystals 
 belong to the cubic system, and such as do not crystallize, all 
 minerals have, in a greater or less degree, the same property. 
 
 But there is one direction in which a line (or any other 
 object) may be viewed through calcspar, without appearing 
 double ; this is in the direction of the axis of the rhombohe- 
 dron. If the two summits of a rhombohedron, or the bases 
 of an hexagonal prism be polished, on placing it over a dot, 
 and the eye immediately above it, we shall see but one image 
 of it. 
 
 In the crystals also, which are referable to a square prism, 
 no double refraction is perceptible in the direction of their 
 axis : in both cases it is called the axis of double refraction . 
 
 In crystals where this kind of symmetry does not exist, as 
 wdien they are derived from prisms that are oblique, or have 
 not a square base, there are two axes of double refraction, 
 or two directions in which only a single image will be per- 
 ceived. 
 
 The property of double refraction may therefore be valuable 
 in assisting us to distinguish minerals, which at first sight 
 appear to resemble each other, if, being cut and polished, or 
 in irregular fragments, we have no indication of their external 
 form. A fragment of red topaz, for instance, will refract 
 doubly : one of spinel ruby, the crystals being octahedral, 
 will not. 
 
 § 17. But as the amount of double refraction is, in most 
 substances, very small compared with that of calcspar, it is 
 seldom possible to discover, by merely looking through them 
 at a line or dot, whether they really possess this property ; 
 besides the difficulty there may be of having traasparent frag- 
 ments of sufficient size to be cut in different directions. A 
 simple experiment, however, with polarized light, will deter- 
 mine the point. 
 
 Light may be polarized by several different methods ; as, 
 by reflection at a certain angle, from a polished surface ; by 
 transmission through plates of tourmaline, &c. For the 
 
13 
 
 POLARIZATION COLOURED RINGS. 
 
 mineralogist, two thin plates of this subtance, cut parallel to 
 the axis of the crystal, afford the most convenient apparatus. 
 They are to be fixed, each in the aperture of a short tube of 
 wood or brass, of such dimensions that one shall be capable of 
 turning within the other. On looking through the two plates, 
 placed with their axes parallel , we shall see, as in any similar 
 case, the brown or green colour of the tourmaline ; but if one 
 of them be turned, so that its axis shall be at right angles to 
 that of the other (their planes being still parallel), the light 
 will be wholly, or almost entirely, intercepted. On introduc- 
 ing between them a fragment or plate of the mineral under 
 investigation, if it do not possess the property of double re- 
 fraction, no change will take place : but if it refract doubly, 
 light will be visible, and in a very singular manner : a number 
 of concentric coloured rings will be seen, intersected by a 
 black cross. On turning either plate of tourmaline one quad- 
 rant of the circle, the appearance will still be the same ; as 
 also when it has described half or three quarters of a revolu- 
 tion : but at all the four intermediate points, a white cross will 
 take the place of the black one, and the coloured rings will 
 occupy the dark spaces that intervened between those of the 
 former set, figs. 1 and 2. 
 
 If the mineral have but one axis of double refraction, and 
 the plate be cut perpendicularly to it, the rings will be circu- 
 
 No. 21. No. 22. No. 23. No. 24. 
 
 lar ; if obliquely, they will be elliptic. 
 
 But if the crystal belong to any of those series which indi- 
 cate two axes of double refraction, there will be two adjoining 
 
TRANSPARENCY LUSTRE. 
 
 19 
 
 systems of coloured rings, traversed by a black cross, No. 23 ; 
 and on turning one of the plates of tourmaline so as to produce 
 the complementary system of rings, they will have the appear- 
 ance represented in No. 24. Many other phenomena pre- 
 sented by minerals, when viewed with polarized light, are 
 extremely curious and beautiful, but they are far too numerous 
 to be detailed here. 
 
 § 18. The character of transparency exists in various de- 
 grees in minerals : some are perfectly transparent (and when 
 colourless also, are said to be limpid ); others, which allow 
 objects to be indistinctly seen through them, are semi-trans- 
 parent : when they transmit only a little light, they are said to 
 be translucent. Some are translucent only on the thin edges 
 of fragments ; others are quite opaque. But it should be 
 observed whether opacity is really a character of the species, 
 or whether it is caused by the intermixture of some foreign 
 matter. Opacity is sometimes also the consequence of decom- 
 position, loss of water, &c. 
 
 § 19. With regard to the brilliancy of minerals, there are 
 several kinds of lustre which are very distinct from each 
 other : for instance, some have a metallic lustre, others a 
 vitreous or glassy lustre : others, again, either from the nature 
 of their texture or structure, exhibit an adamantine , oily, resin- 
 ous, waxy, pearly, or silky lustre.* Many substances, being 
 of an earthy texture, are without lustre, or quite dull: in 
 others, according to their degree of compactness, we find 
 several degrees and varieties of lustre in various parts of the 
 same mass. 
 
 There is also a kind of lustre peculiar to some minerals, 
 denominated semi-metallic ; it is very commonly found in mica, 
 as well as in some metallic ores. 
 
 § 20. The degrees of lustre should also be remarked ; the 
 highest degree, splendent, is applied almost exclusively to the 
 
 * The pearly lustre which is often to be observed on the bases of 
 prismatic crystals, appears to be the result of a laminated structure ; and 
 the silky lustre, of a fibrous structure. 
 
20 
 
 COLOURS OF MINERALS, 
 
 diamond and white carbonate of lead, which from their very 
 high refractive power have a greater brilliancy than any other 
 substance. 
 
 Many crystals are brilliant ; others are shining , glistening , 
 or glimmering : and these terms apply also to the appearance 
 of the fracture, which should always be observed when re- 
 cently made, and before it loses the form and lustre that are 
 peculiar to it. 
 
 Some minerals which are soft, and have little or no lustre, 
 become shining when scratched by a sharp point. 
 
 § 21. The colours of minerals are either essential to them, 
 as in the sulphurets, oxydes, and acidiferous compounds of 
 most metals, and in those species of which they are essential 
 constituents ; or they are the effect of a casual intermixture of 
 these substances in species which, when pure, are naturally 
 colourless. Of the latter sort are the colours of felspar, calc- 
 spar, rock salt, marble, and jasper, in which the various tints 
 of red and yellow are generally due to the oxyde and hydrous- 
 oxyde of iron. Other minerals derive a brilliant green colour, 
 some from carbonate of copper, others from the oxyde of 
 nickel or of chrome. In species of which the colour is a 
 permanent character, its intensity is often so far varied by a 
 difference of texture or a confused crystallization, that red, 
 brown, and green substances appear, in a mass, to be black ; 
 but on being pulverised, their true colour will be seen ; it is 
 therefore advisable, in describing a mineral, to state what its 
 colour is when reduced to powder. 
 
 The intermixtures of colouring matter, which are merely 
 mechanical, render a mineral more or less opaque : thus, the 
 red and yellow jasper, already mentioned, are calcedony (which 
 when pure is highly translucent, or even semi-transparent), 
 coloured by minute particles of oxyde of iron, which are them- 
 selves opaque. But colours, which, though they may not be 
 essential to a species, are the result of chemical combination , do 
 not impair its transparency: such is the violet tint of amethyst, 
 which is derived from a minute portion of the oxyde of man- 
 
ESSENTIAL OR ACCIDENTAL. 
 
 21 
 
 ganese combined with the quartz ; and the green of the eme- 
 rald, which is owing to the oxyde of chrome. 
 
 In consequence of the variable quantity of colouring matter, 
 whether chemically combined or otherwise, many substances 
 present various tints and shades of colour ; so that we par- 
 ticularise them as blood-red , flesh-red , chestnut -brown, lemon- 
 yellow , sky-blue , &c. 
 
 Accidental colours, being unequally distributed, often pro- 
 duce parallel bands, either straight or curved, and clouded 
 forms, as in agates : sometimes the colour takes the form of 
 leaves and moss, or runs through the mass in veins, as in 
 marble. 
 
 § 22. There are still other colours, which are neither essen- 
 tial to minerals, nor yet produced by intermixture. Some, as 
 the sulphuret of antimony, exhibit a brilliant superficial tar- 
 nish, in which the prismatic colours are regularly arranged. 
 In transparent substances, prismatic colours are perceived in 
 the interior, and arise from minute cracks or fissures contain- 
 ing films or particles of air : these are often moveable by a 
 slight pressure. 
 
 § 23. A very curious peculiarity of colour called polychro - 
 ism * is connected with the phenomenon of double refraction. 
 Some minerals, placed between the eye and the light, transmit 
 different colours in different directions : tourmalines, viewed 
 parallel to their axis, are generally opaque ; perpendicularly to 
 it, they appear to be green, red, brown, &c. This difference 
 is not observable in all doubly refracting substances ; but in 
 some which have two axes of double refraction, three different 
 tints have been observed. Minerals crystallizing in the cubic 
 system never transmit more than one colour, if their composi- 
 tion and texture be homogeneous throughout. 
 
 § 24. In some minerals, a peculiar light is produced either 
 by friction or by heating them, which is called phosphorescence. 
 On rubbing together two fragments or pebbles of quartz, a 
 faint greenish light will be perceived : the same effect results 
 * From two Greek words — polus, many, and chroa , colour. 
 
22 
 
 PHOSPHORESCENCE — HARDNESS. 
 
 from certain marbles. Other substances, when placed on a 
 heated shovel, emit a brilliant phosphorescence, which in 
 some is green ; in others, pale violet. The best mode of con- 
 ducting this experiment, if the specimen is powdered, or in 
 small fragments, is to strew it on a shovel heated nearly to 
 redness : but if it be an inch or two in length, it is better to 
 heat it slowly, and not beyond the necessary degree ; by 
 which means the operation may be frequently repeated without 
 injuring it. 
 
 § 25. The hardness of minerals is a character very useful in 
 distinguishing them : but it is necessary to ascertain it with 
 some precision, by comparing it with that of others. In 
 order to facilitate this comparison, a scale of hardness has 
 been arranged, which obviates the use of the indefinite terms, 
 hardy very hard , rather softy &c., and it is almost equally vague 
 to say that a mineral is harder or softer than some others, 
 unless these standards of comparison be very limited in num- 
 ber. The scale of hardness invented by Mohs, and which is 
 very generally adopted, is subjoined, and may be referred to 
 when this character is described, which is now very usual, 
 by a numeral. 
 
 1 . Talc — laminated variety 
 
 2. Rocksalt (or uncrystallized Gypsum) 
 
 3. Calcspar — transparent 
 
 4. Fluorspar — crystalline 
 
 5. Apatite — transparent 
 
 6. Felspar — white, crystalline 
 
 7. Quartz — transparent 
 
 8. Topaz — transparent 
 
 9. Sapphire — cleavable 
 
 10. Diamond.* 
 
 * The interval between Nos. 2 and 3, and between 5 and 6, being 
 rather greater than the others, some mineralogists have thought it advis- 
 able to introduce between the former, Foliated Mica, numbering it 2-5 
 (two and a half) ; and between the latter, Scapolite, 5*5 ; in order not to 
 alter the original numeration of the scale. 
 
TENACITY ELASTICITY. 
 
 23 
 
 It must be remembered that hardness signifies, in mineralogy, 
 the resistance which a mineral offers when we attempt to cut 
 or scratch it ; and is very different from its tenacity , by which 
 we understand its power of resisting a blow. The diamond 
 and the sapphire, the former the hardest substance in nature, 
 and the latter capable of cutting everything except the dia- 
 mond, are so brittle that they may easily be shattered by the 
 blow of a hammer ; while others, which are very soft, that 
 is to say, easily cut or scratched, offer great resistance to a 
 blow. 
 
 § 26. The degree of tenacity of minerals results from their 
 elasticity , and is a character depending on their structure. In 
 some, which are compact, it is evident from their rebounding 
 when thrown against a hard surface ; in others, which are 
 laminated, from the ease with which the laminae, after being 
 bent, return to their former position : several minerals also are 
 flexible without being elastic; this is the case with several 
 fibrous substances. 
 
 § 27. The comparative weight or specific gravity of minerals 
 is a highly important character, and will often serve to iden- 
 tify species. The difference of weight of many substances is 
 so great, that we may frequently recognise them immediately 
 by this means : jewellers will thus generally distinguish a 
 sapphire or topaz from an amethyst or rock-crystal, or from 
 coloured glass, notwithstanding a similarity of colour and 
 form. It is therefore desirable to ascertain the specific gravity 
 of minerals with precision. 
 
 In order to do so, we must have a standard of comparison 
 which may be termed unity . For this purpose we make use 
 of distilled water, at the temperature of about sixty degrees. 
 When, therefore, the specific gravity of gold is said to be 19; 
 of lead, 11 ; and of topaz, 3 5 ; it is meant that gold is nine- 
 teen times, lead eleven times, and topaz three and a half times 
 as heavy as water. 
 
 The method of determining the specific gravity of any solid 
 body is very simple : it is first to be weighed exactly, in a 
 
24 
 
 SPECIFIC GRAVITY. 
 
 delicate balance ; secondly , it is to be immersed in water, and 
 again carefully weighed ; thirdly , the second weight, which is 
 always less than the former, is to be subtracted from it ; 
 fourthly , the first or absolute weight is to be divided by the 
 difference of the two : the result will be the specific gravity of 
 the specimen under examination. For, the weight lost by the 
 immersion in water, is the weight of a quantity of water, 
 equal in bulk to that of the solid : we therefore make a com- 
 parison between a certain bulk of solid matter and an equal 
 volume of water.* 
 
 Thus, a crystal of topaz weighing 100 grains weighs, when 
 immersed in water, only 71*43 grains; and if we divide 100 
 by 28*57, which is the difference of the two weights, the result 
 will be 3*5, which is the specific gravity of topaz. 
 
 In taking the specific gravity of a mineral, it is scarcely 
 necessary to remind the student that it should be most care- 
 fully separated from every foreign substance : but even when 
 specimens are selected with the greatest regard to purity, it 
 will still be found that the results of different experiments vary 
 a little. This appears to arise from a difference in their com- 
 pacity, or mode of aggregation of their particles. In several 
 species, of which a number of specific gravities were taken by 
 M. Beudant, he found uniformly, that small well-formed crys- 
 tals gave the highest numbers. For instance, small crystals 
 of calcspar were 2*7223 to 2*7234; while portions of a large 
 dodecahedral crystal gave a specific gravity of 2' 7068, and a 
 piece of stalactite, only 2*704. It is desirable, on this account, 
 to state, in the description of a species, its highest and lowest 
 specific gravity. 
 
 § 28. The property of taste is confined to the soluble 
 minerals, of which some are astringent , as the sulphate of 
 iron; a few, alkaline , as carbonate of soda; others, bitter, 
 
 * A scale made of open wire-work is preferable for immersion 
 in water, as it offers less resistance to movement in the liquid. In 
 all cases it should be accurately balanced when in the water, against the 
 other scale. 
 
TASTE — ODOUR. 
 
 25 
 
 as Epsom salt ; or sour , as the sulphuric acid which occurs 
 among recent volcanic products : a few, as sal ammoniac, are 
 pungent. 
 
 § 29. There are very few minerals which exhale any odour , 
 unless by the application of heat or moisture. The bituminous 
 odour is generally perceptible in the varieties of bitumen, and 
 the inflammable substances which contain it ; and this becomes 
 stronger when they are heated. The smell of sulphur, which 
 is known to most persons, is immediately perceived in its 
 compounds when they are exposed to heat ; and by the same 
 means the odour of arsenic becomes evident : it has a great 
 resemblance to that of garlic. Friction is in many cases 
 sufficient to produce this effect, as in certain bituminous 
 limestones. 
 
 On the other hand, many substances when breathed on, or 
 otherwise exposed to a slight degree of moisture, give off an 
 odour which, from being strongly perceptible in all kinds of 
 clay, is called the argillaceous odour. 
 
 § 30. All minerals are more or less susceptible of becoming 
 electric , either by friction , by pressure , or by heat ; in some, 
 this property may be excited by all these methods. A topaz, 
 a tourmaline, and a number of other minerals, when rubbed 
 on a piece of woollen cloth, will, like a stick 
 of sealing-wax or glass rod (so excited,) 
 attract small light bits of cotton or thin 
 paper. But the metals, and those ores 
 which approach to a metallic state, being 
 conductors of electricity, this result cannot 
 be obtained unless they are previously iso- 
 lated, by placing them on a support of glass, 
 or some other non-conducting substance. 
 
 A very small piece of gilt paper attached by 
 a silk thread to a bent glass rod, forms a 
 simple apparatus which will exhibit the electricity a mineral 
 has thus acquired : on approaching it to the gilt paper it 
 will immediately attract it. The specimen, also, should be 
 
 c 
 
26 
 
 ELECTRICITY MAGNETISM* 
 
 suspended by a silk thread, or held in a pair of pincers* 
 having a glass handle. 
 
 The substances which become electric by heat, such as 
 tourmaline and topaz, usually exhibit electric poles : that is to 
 say, one end of the crystal becomes positively, the other nega- 
 tively, electric. This may be ascertained by previously com- 
 municating to the gilt paper either kind of electricity. For 
 instance, when the crystal is heated, let the gilt paper be 
 touched by a stick of sealing-wax that has been well rubbed : 
 if the crystal, on approaching the apparatus, repels the paper, 
 that end is also negatively electric , and it will be found that the 
 other end attracts it, and is therefore positively electric . The 
 crystals which acquire electric poles by heat, have another 
 peculiarity : namely, that their opposite extremities are dif- 
 ferently modified : tourmalines are sometimes terminated at 
 one end by three, at the other by six or nine planes. This is 
 yet more striking in the substances whose crystals are cubes 
 modified on the alternate solid angles. 
 
 However curious we may consider the electric phenomena 
 of minerals, they appear to be manifested with too much 
 uncertainty to form a distinguishing character. Different 
 crystals of the same substance will acquire, some negative, 
 others positive electricity, according as they are transparent or 
 otherwise ; in general, transparent crystals with bright po- 
 lished faces become positively electric; and such as are not 
 limpid, or have a rough exterior, become negatively electric. 
 
 § 31. The only mineral which is capable of becoming a 
 magnet or loadstone, is the magnetic oxyde of iron : this 
 mineral alone exhibits the magnetic poles; but many iron ores, 
 and even many other substances which contain a large propor- 
 tion of iron, not too highly oxydised, will attract the magnetic 
 needle perceptibly. The metals cobalt and nickel likewise pos- 
 sess this property, but less powerfully. 
 
 * The latter plan is objectionable if we wish to ascertain whether the 
 substance is capable of becoming electric by simple exposure to heat, 
 because many which are not so become electric by pressure. 
 
ELEMENTS OF MINERALS. 
 
 27 
 
 § 32. Before we speak of the characters which minerals 
 offer when chemically examined, it will be proper to say a 
 little about the various elementary substances of which they 
 consist. We are acquainted with about 500 mineral species : 
 some of these are simple or elementary substances : that is, our 
 chemical knowledge has not yet enabled us to decompose or 
 separate them into different elements. Such are the diamond , 
 which is carbon in its purest state, and the metals, as gold , 
 copper , antimony, &c.; but the greater number of these ele- 
 mentary bodies exist only in combination with these, or with 
 each other. 
 
 Many substances which might, at first sight, be thought to 
 be simple ones, are in reality compounds. Water, for instance, 
 consists of two kinds of gas, oxygen and. hydrogen, chemically 
 combined. In the atmosphere, oxygen exists with nitrogen 
 gas, in the proportion of 1 to 4. Oxygen, although it is never 
 found alone in nature, exists in so many substances, forming 
 oxydes and acids, that it is one of the most abundant mineral 
 elements. In the earths, lime, flint (or silica), clay (or alu- 
 mina), and magnesia, it is combined respectively with the 
 metals, calcium , silicium, aluminium, and magnesium, which are 
 called their bases . It exists also united with iron, copper, tin, 
 lead, and some other metals, in their ores : the above-named 
 combinations are called oxydes. With sulphur, oxygen pro- 
 duces sulphuric acid ; with nitrogen, nitric acid ; with carbon, 
 carbonic acid or fixed air. These acids, again, are combined 
 with the earths, alkalies, and other oxydised metals, forming 
 sulphates, nitrates, and carbonates. Some of the oxydised 
 metals too, as arsenic and chrome, play the part of acids, and 
 mineralise other metals and earths ; therefore, we have chro- 
 mate of lead, arseniate of iron , of lime, &c. : and, among the 
 earths, it is found that silica is the most active or mine- 
 ralizing agent ; producing silicates of the earths, alkalies, and 
 metals. 
 
 Sulphur, not acidified, is found combined with several of 
 the meffals, as iron, silver, copper, &c. : these combinations 
 
 c 2 
 
23 
 
 ISOMORPHISM. 
 
 are termed sulphurets ; two or more are often combined in the 
 same species. In like manner, the compounds of arsenic are 
 called arseniurets , of tellurium tellururets, &c. 
 
 § 33. Some metals, as iron and manganese, combine with 
 different proportions of oxygen, and these combinations, which 
 are always very different in their properties and characters, are 
 distinguished by the terms protoxyde and peroxyde , the latter 
 always implying a larger quantity of oxygen than the former : 
 in like manner, some of the earths, as silica and alumina, are 
 peroxydes; while others, as lime and magnesia, are protoxydes. 
 It is important to remember this distinction, because a curious 
 property called isomorphism* is connected with it. Isomor- 
 phism signifies similarity of form : and it is found that there 
 are in nature several elements which have so close a resem- 
 blance in the form of their molecules or particles, and in 
 their crystalline tendencies, that in numberless minerals they 
 replace each other, without sensibly affecting the crystalliza- 
 tion of the compound ; or they produce only a slight varia- 
 tion in some of the angles. Thus, in the different kinds of 
 garnets, we find in some more alumina, in others more perox- 
 yde of iron, without any change of form : and in the different 
 varieties of augite and hornblende, we find lime and magnesia 
 replaced, wholly or in part, by the protoxydes of iron and 
 manganese ; their crystallization remaining the same. These 
 elements are therefore said to be isomorphous : and besides 
 those just mentioned, the same similarity exists between the 
 protoxyde of lead and the earths baryta and strontia ; between 
 arsenic and phosphoric acid and some few other substances. 
 
 § 34. The principal distinction to be made, then, between 
 the constituents of minerals, is this : a certain number of them 
 are the active elements which mineralise the others.\ The most 
 
 * Isos, Gr., similar, and morphe form. 
 
 f To explain the classification into electro-negative and electro-positive 
 substances of the elements of the mineral kingdom, would be encroaching 
 too much on the province of Chemistry ; or, at least, would be incompa- 
 tible with a work of so limited a nature as the present. 
 
CHEMICAL EXAMINATION OF MINERALS. 
 
 29 
 
 simple compounds (consisting of only two elements) are called 
 binary , and in those which occur in nature it is found that one 
 of the constituents must always be one of the twelve following 
 substances : 
 
 Oxygen 
 
 Antimony 
 
 Sulphur 
 
 Selenium 
 
 Arsenic 
 
 Tellurium 
 
 Chlorine 
 
 Mercury 
 
 Carbon 
 
 Gold 
 
 Fluorine 
 
 Osmium 
 
 § 35. But the greater number of the fifty-nine elementary 
 substances known to us, form but a small portion of the earth, 
 as far as we are acquainted with it. The granite and trap 
 rocks, the limestone, slate, chalk, sand, and clay strata, which 
 we meet with all over the globe, consist principally of the 
 earths above named, the alkalies potash and soda, iron, car- 
 bonic acid, and chlorine. Water, also, enters largely into the 
 composition of many substances as an essential component : 
 this will not appear extraordinary, if we call to mind the familiar 
 experiment of casting with plaster of paris. 
 
 Of the metals, some, as silver, copper, tin, lead, although 
 they are abundant in comparison with tellurium, cerium, and 
 others, occur, with the exception of iron (which enters as a 
 necessary constituent into many of the so-called earthy mine- 
 rals), only in very thin beds called veins , which traverse some 
 of the siliceous and calcareous rocks ; while many have been 
 found only in a few distant localities, and are unknown, except 
 to mineralogists. 
 
 § 36. With regard to the chemical examination of minerals, 
 there are two modes of operation, called the moist and the dry: 
 in the former, they are dissolved, either in water, or, if that is 
 not possible, in some acid ; in the latter, they are exposed to 
 great heat by means of a blowpipe . For the mineralogist this 
 mode of operation is by far the most convenient; both because 
 the results are quickly obtained, and because very little appa- 
 ratus is necessary : he requires, for his furnace, only a lamp or 
 
30 
 
 BLOWPIPE. 
 
 candle ; some strips of platinum foil, and a pair of pincers with 
 tips of the same metal, for supporting the specimens to be 
 assayed; or, in some cases, a piece of well-burnt and solid 
 charcoal ; and a few small bottles containing fluxes. 
 
 § 37. The blowpipe, in its simplest form, is a bent tube, 
 nine or ten inches long ; at one extremity tapering to a fine 
 point. It is used to direct and concen- 
 trate a flame, by supplying to it a constant 
 stream of air in one direction ; the small 
 end being placed just within the flame, and 
 the air being furnished by the operator a 
 blowing through it. 
 
 Some difficulty may be experienced, at 
 first, in producing an equal and uninter- 
 rupted stream of air and a steady flame : 
 it can only be effected by supplying the 
 air, not immediately from the lungs, but 
 from the mouth, as from a reservoir , which 
 must not be allowed to become ex- 
 hausted; otherwise, the experiment will be incessantly im- 
 peded by the necessary act of respiration. 
 
 Some blowpipes have a cylindrical or globular cavity, in 
 which the moisture of the breath is condensed and retained ;* 
 it might otherwise be carried by the draught into the flame, 
 and would interfere with the experiment. 
 
 A silver tube is the best, as not liable to corrosion ; brass 
 communicates an unpleasant smell to the fingers; but a cheaper 
 instrument may be made of tinned iron, the cavity being square 
 and placed at the bend. In all cases, however, the tip should 
 be of platinum and removable, that it may be cleansed if neces- 
 sary, in acid, or by heating it to redness. 
 
 A small lamp, fed either with oil or melted tallow, will fur- 
 nish a good flame for the exercise of the blowpipe ; but a 
 candle with a large wick may be used, and, in travelling, is 
 perhaps the most convenient. 
 
 * This cavity is made in two parts and unscrews at a. 
 
FLUXES. 
 
 31 
 
 When the student can produce a steady flame with this 
 instrument, he will find that it now consists of a cone of yellow 
 light, inclosing a blue one. The heat is most intense at the 
 extremity of the blue flame : this is called the reducing flame , 
 because it de-oxydises, wholly or in part, the substances that 
 are exposed to it, and it is capable of melting a great number 
 that are not fusible in the outer one. The latter is called the 
 oxydising flame , because, as it does not entirely prevent the 
 contact of the air, it permits the subject of experiment to 
 become oxydised. 
 
 In the inner flame, some of the metallic oxydes are reduced 
 to the metallic state ; and their reduction is assisted by placing 
 them on a piece of charcoal as a support, because it absorbs 
 the oxygen from them when heated. For this purpose, a small 
 hollow may be scraped in the charcoal, and the mineral (pre- 
 viously crushed or powdered) fixed in it with a little wax 
 or tallow, which will prevent it from being displaced on expo- 
 sure to the draught of air, and will quickly burn away. 
 
 A quantity, varying from the size of a mustard seed to that 
 of a peppercorn, is ample for most experiments. Sulphurets, 
 when heated, give off the odour of sulphur, and after some 
 time they are generally reduced to the metallic state. When 
 arsenic is combined with them, the smell of garlic will be per- 
 ceived : and the few which contain selenium , afford a pungent 
 odour like that of horseradish. 
 
 § 38. Some minerals, both earthy and metallic, are fusible 
 by the blowpipe without addition : but many others cannot be 
 melted unless mixed with some alkaline or saline substance, 
 with which they fuse into a glass, more or less transparent, or 
 a kind of enamel : these salts are called fluxes : carbonate of 
 soda, borax, and salt of phosphorus, are most commonly used, 
 and they may generally be placed with the subject under 
 examination on a slip of platinum foil. In some cases, the 
 glass produced by fusion is colourless, containing small glo- 
 bules of the reduced metal ; in others, it receives from the 
 metal a colour which is peculiar to it : thus, the ores of cobalt 
 
32 
 
 SOLUTIONS EFFERVESCENCE. 
 
 melted with borax (or common glass,) will always produce a 
 fine clear blue colour : those of manganese, a rich purple like 
 that of the amethyst. It must be remarked, however, that 
 the saine metallic oxyde will produce different colours with 
 different fluxes, or in the two flames; and therefore, if the 
 result of one experiment should not be satisfactory, it may 
 often be verified by a second. The annexed table, showing 
 the results obtained by subjecting several oxydes to the action 
 of the blowpipe, with different fluxes, will be found useful for 
 reference. 
 
 When a mineral is heated in a closed glass tube, by direct- 
 ing the flame against and beneath it, if it contain water, it will 
 be volatilized, and condensed on the upper surface. If fluorine 
 be one of the components, the glass may be corroded by it : 
 but this gas is not always disengaged without fusion with salt 
 of phosphorus. 
 
 § 39. As it is not possible in this introduction to detail 
 most of the experiments for examining minerals by solution, 
 we will observe. First, that effervescence on the application of 
 an acid generally indicates a carbonate : in all carbonates of 
 lime the effervescence is very brisk, but in some other species 
 it is scarcely perceptible without the assistance of heat. Se- 
 condly, that some minerals that do not effervesce, when dis- 
 solved in acids, are converted into a gelatinous substance ; this 
 is the case particularly with some siliceous minerals that con- 
 tain a portion of alkali : heat is often necessary to accomplish 
 this change, and the acid employed should be strong ; but to 
 produce effervescence, the acid should be diluted with water. 
 
MINERALOGY, 
 
 33 
 
 P 
 
 P 
 
 O 
 
 ffi 
 
 P 
 
 co 
 
 O 
 
 a 
 
 Ph 
 
 P 
 
 O 
 
 5 
 
 <: 
 
 m 
 
 a 
 
 H 
 
 P 
 
 Ph 
 
 to 
 
 .S £ 
 
 'o 22 
 8 2 §• 
 c .g a 
 ° 8 
 -S 1 ? 2 
 
 ££ &8*2 
 03 U CO 
 
 £►» to A 
 
 - a > 
 P & 
 
 03 
 
 03 ?• 
 
 c i 2 « 
 
 O O S O 33 
 
 'o 'o o o .5 
 
 03 03 2 o ,c 
 
 £ o 
 
 2 S3 * 
 -° 0 S 3 
 
 ^ s 8 
 
 .S " H 
 
 £ ^ tO 
 O 3 ft 
 S O (D 
 
 03 03 
 
 * ^ 
 
 4 - § 
 
 V U 
 
 r*3 
 
 *03 03 
 
 X 
 
 < 
 
 a 
 
 o 
 
 ffl 
 
 a 
 
 H 
 
 P 
 
 Pp 
 
 s 3 * o £* 
 
 o 03 oT <*_ "S 
 
 w S a 
 
 £ 
 
 s^rQ bcrS o 
 
 o ° -5 a P 3 
 
 r bb 03 lib 2 
 
 •g I 
 
 C -*-j 3 ri I 
 
 2 > 03 03 * S3 13 
 
 .3 g to S 5- g 
 
 ►* g _2 S3 3 5 £ 
 
 J -ft c3 
 
 ,2 £' 
 
 C ^03 
 
 p*> iP 
 
 S S 3 33 !> 
 
 to 
 
 ,0 
 
 <« co 
 03 03 03 
 
 T 3 •'a T 3 
 
 2 rS3 ft 
 
 0^0 
 
 “ Sb 
 
 & $ * 
 
 03 
 
 »H 
 
 to 
 
 *eS 2 IP 
 
 tl O r3 
 03 g bO 
 2 *£ 
 
 T 3 r cT r o jE 2 
 
 •— • 03 03 J 2 0 
 
 O ;-i 33 ~ 
 
 03 JT 03 03 
 
 b -S *-8 
 
 > 0 ' s ■ 
 
 ft -t-> 
 '2 03 © o 
 
 ft bO 
 
 2 o ja 
 
 ^- 1 |i 
 
 Pm 
 
 O 
 
 CO 
 
 p 
 
 Q 
 
 >- 
 
 X 
 
 O 
 
 2 
 
 3 
 
 *C 
 
 2 
 
 33 .2 
 
 03 .T3 .S 
 
 « O' 
 
34 
 
 CLASSIFICATION. 
 
 SECTION II. 
 
 Minerals — and in the arrangement of the unorganised 
 portion of the globe may be included water, the air, and other 
 natural gases — are naturally divisible into three classes, based 
 on the mineralising (or electro-negative) principle they contain. 
 Each of these mineralising elements is the base or type of a 
 family; the families are divided into genera, each containing 
 one or more species. The substances which are comprised in 
 the first class have for their type elements which are capable 
 of forming 'permanent gaseous combinations with oxygen, or with 
 hydrogen, or with fluorine : they have, therefore, received the 
 name of gazolytes . These substances are silicium, boron, car- 
 bon, hydrogen, nitrogen, sulphur, chlorine, bromine, fluorine, 
 selenium, tellurium, phosphorus, and arsenic. 
 
 In the second class, the mineralising substances are charac- 
 terised by forming colourless solutions in acids, and may, there- 
 fore, be called leucolytes .* The bases of the families in this 
 class are antimony, tin, bismuth, mercury, silver, lead, alu- 
 mina, magnesia. 
 
 The third class unites minerals in which the bases of the 
 families produce coloured solutions in acids, whence they h^ve 
 been named chroicolytes : f these substances are manganese, 
 iron, cobalt, copper, uranium, palladium, platinum, gold, chrome, 
 molybdenum, tungsten, titanium, tantalum. 
 
 Family I. — Silicides. 
 
 Genus I. Silica. 
 II. Silicates. 
 
 * From two Greek words, leucos white, and lutos soluble, 
 t Chroikos coloured, and lutos . 
 
QUARTZ. 
 
 35 
 
 The genus silica contains but two species — 
 
 1. Quartz. 2. Opal. 
 
 Quartz presents very numerous varieties of form, colour, 
 transparency, &c. : but it may be distinguished into two prin- 
 cipal kinds, vitreous and calcedonic. 
 
 Vitreous Quartz in its purest and crystalline state is 
 familiarly known as rock-crystal , a transparent colourless sub- 
 stance which may be distinguished by the following cha- 
 racters : 
 
 Insoluble in all acids. 
 
 Infusible alone by the blowpipe, but easily melted with the 
 addition of caustic alkali into a glass. 
 
 Giving off no water by calcination. 
 
 Crystallizing in the rhomb ohedral system ; primary form a 
 slightly obtuse rhomb ; inclination of two adjoining faces, 
 94° 15'. 
 
 Possessing a certain degree of hardness, considerably greater 
 than that of glass, = 7. 
 
 Specific gravity = 2*65. 
 
 Lustre, when transparent, vitreous and shining or brilliant. 
 
 The cleavages are obtained seldom and with uncertainty, 
 and when they are produced the surfaces are generally some- 
 what curved, showing a tendency to the conchoidal fracture 
 which characterises most varieties of this mineral. 
 
 Primary crystals are of rare occurrence, and are generally 
 
 No. 27. No. 28. No. 29. 
 
 very small. The double six-sided pyramid, also, is seldom an 
 
36 
 
 QUARTZ — AMETHYST. 
 
 inch in diameter ; but prismatic crystals are found sometimes 
 of very large dimensions. The faces of the pyramids which 
 terminate them are sometimes equal and regular, but in other 
 specimens their size is extremely unequal. It is worthy of 
 remark, that the faces of the prism, however bright, are almost 
 invariably striated transversely to the edges ; but those of the 
 pyramids are perfectly smooth and polished. Specimens of 
 quartz frequently exhibit only the pyramids of crystals closely 
 grouped : this is mostly the case when the structure of the 
 mass is radiated. 
 
 Crystallized quartz is of various colours ; when of a purple 
 tint, it is called amethyst. The ancients valued this gem for 
 the property which their superstition attributed to it, of pre- 
 serving from intoxication any person who wore it.* 
 
 In Brazil, rock-crystal is found of a clear topaz yellow, of 
 various depths. Smoke-brown crystals, also, which are called 
 Cairn Gorm stones, f are often perfectly transparent ; but this 
 colour is sometimes so dark as to render the quartz black and 
 opaque. 
 
 Red oxyde of iron dispersed through quartz gives it a bright 
 red colour, but renders it opaque : very perfect crystals of 
 this kind, of a small size, are found at St. Jago de Compos- 
 tella, in Spain. The neighbourhood of Bristol furnishes speci- 
 mens of a similar kind, as well as yellow quartz. These ferru- 
 ginous varieties, called, by the Germans, Eisenkiesel (ironflint), 
 consist sometimes of minute crystals aggregated together, and 
 cemented by ochry oxide of iron, forming a granular mass. 
 
 Quartz is occasionally found in crystalline forms belonging 
 to other minerals, such as the cubes of fluorspar, lenticular 
 crystals of gypsum, and dodecahedrons of calcspar : these are 
 called pseudomorphous crystals, and have neither transparency 
 nor brilliancy. In some cases, the quartz has formed an in- 
 crustation on crystals which have afterwards been removed by 
 
 * A , Gr., not, and methustos drunk, 
 t From the mountain Cairn Gorm in Scotland. 
 
SAND PRASE. 
 
 37 
 
 decomposition : in others, quartz has filled up, and, as it were, 
 been cast in the empty mould left by previous decomposition. 
 
 There is also a singular variety of quartz of so spongy a 
 texture, that the multitude of insterstices filled with air enable 
 it to float on water : it is called fioatstone or nectic quartz, 
 and is found in the calcareous formations near Paris. 
 
 Massive quartz of a pale rose colour, strongly translucent, 
 is found in considerable quantity in Bavaria : it is generally 
 much veined, and the colour is unequal. It occurs in other 
 localities, but of inferior beauty. The fracture of rose quartz 
 has a somewhat oily lustre, which is observable also in the 
 white massive quartz which forms considerable veins in gra- 
 nite, slate, and other rocks : this kind is nearly or quite 
 opaque. 
 
 Sand is quartz in minute grains, rounded or angular, some- 
 times white, but more often coloured reddish or yellowish 
 brown, by oxyde of iron. In sandstone the grains are ce- 
 mented, and intermixed with sometimes siliceous, sometimes 
 argillaceous, and less often by calcareous matter. Of the 
 latter kind, beautiful groups of crystals have been obtained 
 at Fontainbleau, having the form of a rhombohedron of 
 calcspar. 
 
 Sandstone is found in Brazil and China, which, when cut 
 into thin slabs, is distinctly flexible. 
 
 Prase* is quartz rendered nearly opaque, and of a dark 
 green colour, by minute fibres of actinolite penetrating it 
 in all directions. Saxony and Bohemia produce the finest 
 specimens. 
 
 The beautiful stone called avanturine is quartz of a finely 
 granular structure, reflecting the light from an infinity of 
 brilliant points. There is another kind in which an effect 
 nearly similar arises from the interspersion of minute scales 
 of gold-coloured mica. 
 
 The Cat's Eye , a gem much prized in the East, is quartz of 
 
 * Prason , Greek, a leek ; from its colour. 
 
38 CAT’S EYE CALCEDONY — ONYX. 
 
 a closely fibrous structure, so that when cut in a convex form 
 it reflects, like satin spar, a bright band of light with a silky 
 lustre. Its most usual colours are greenish grey or a deep 
 orange inclining to brown. It has been brought from near 
 the Cape of Good Hope; but Ceylon is its chief locality. 
 The finest amethysts are brought from India and Mexico : the 
 largest rock-crystals from Madagascar. Avanturine is often 
 found in rolled pebbles, in Spain, Brittany, and some other 
 places ; also, massive (quartz rock) in some parts of the Alps, 
 and Scotland. 
 
 Calcedonic quartz . — In its chemical characters it nearly re- 
 sembles rock-crystal : but when calcined it becomes white : 
 its hardness is the same, with greater tenacity. The fracture 
 of all the varieties is conchoidal ; in black flint very large and 
 perfect, but seldom having any lustre. 
 
 Calcedony is in general strongly translucent, sometimes 
 semi-transparent, and of a bluish or yellowish- white colour; 
 more rarely of a pale blue, inclining to lavender. In some 
 rocks it fills the greater part of veins in parallel layers of 
 different shades, alternately translucent and opaque : and it 
 lines, with similar layers, large and small cavities, partly filling 
 their interior with stalactitic and mammellated forms, which 
 are sometimes covered with quartz crystals. Very fine speci- 
 mens of this kind are obtained from the basaltic and amygda- 
 loidal rocks of the Ferroe Islands and at Oberstein,* in the 
 Palatinate, where this and many other varieties of calcedony 
 and agate form large veins, and have been quarried for ages. 
 
 Onyx is a striped calcedony formed of alternate layers of 
 brown and white : this kind has been much esteemed since a 
 very early period for the small sculptures of heads and figures 
 called cameos . By the skill of the artist, a brown or a white 
 layer is made to serve as a back ground to the figures which 
 are left in relief on it : and by cutting it to different depths 
 different tints are obtained, suited to the various parts of the 
 
 * About 30 miles southward from Coblentz. 
 
CAMEOS — SARDONYX — HORNSTONE. 
 
 39 
 
 subject. The ancients have left many beautiful works of this 
 description ; among others, there is, in the National Museum 
 at Paris, one representing the Apotheosis of Augustus, which 
 measures eleven inches by nine. The Mantuan vase, at 
 Brunswick, supposed to be the largest cameo in existence, 
 is a vessel about seven inches high, shaped like a cream-jug : 
 the figures, which are white and yellow, relieved on a brown 
 ground, represent Ceres and Triptolemus in search of Pro- 
 serpine. 
 
 Carnelian* is a variety of calcedony which has a slightly 
 shining lustre when broken : the white and pale red carnelians 
 are mostly cut from pebbles which have naturally those colours: 
 but when they are deep red they have had their tints bright- 
 ened by exposure to the sun’s rays. In its native state, this 
 kind appears of an intense brownish red ; and in commerce is 
 generally called sarde.\ Carnelian pebbles are common in 
 many of the sandy plains of Africa, India, and Asia Minor. 
 
 Sardonyx implies a striped or onyx calcedony, in which some 
 of the bands are of a red colour. 
 
 Flint is a well-known variety of compact silica, which occurs 
 chiefly in pebbles or nodules. The black flints that are used 
 for guns are distributed through the chalk in extensive beds : 
 they are often partly calcedonic, or contain crystallized quartz 
 in their cavities. The analyses of flint show that in some 
 instances a minute proportion of carbon, and sometimes of 
 carbonate of lime, is combined with it, supposed to be the 
 remains of organised matter. 
 
 Hornstone differs from flint chiefly in having a less even 
 texture, and in breaking with a splintery uneven fracture ; it 
 constitutes large masses and beds in limestone rocks, and is 
 frequently the petrifying substance of wood and madrepores, 
 in which the organic structure is perfectly distinct, and the 
 colours are sometimes beautifully varied. 
 
 * Carnelian ; came from caro } Lat., flesh, on account of its colour. 
 
 f Sard ; either from Sarx , Gr., flesh, or Sardis in Lydia, whence it was 
 first obtained. 
 
40 
 
 CHRYSOPRASE — JASPER. 
 
 Chrysoprase* is calcedony of a bright clear green colour, 
 which it derives from a minute portion of the oxyde of nickel. 
 It is peculiar to Lower Silesia. When the colour is equal, and 
 the chrysoprase strongly translucent, it is very beautiful, and 
 much valued as an ornamental stone. 
 
 Bloodstone or Heliotrope f is an intimate mixture of calcedony 
 with a substance called green earth , which owes its colour to 
 iron. It is opaque, or nearly so, unless when the mixture of 
 the two minerals is incomplete. The red spots, which it often 
 contains, are jasper; but it is said that the name bloodstone 
 is not derived from these, but from a belief that the stone had 
 power to stanch an effusion of blood. 
 
 In moss agates and mochastones, green earth and other 
 colouring matters occasion dendritic forms -which resemble 
 leaves and moss. But agate is a name given to many com- 
 binations of calcedony, carnelian, quartz, amethyst, and even 
 flint and jasper. 
 
 The last-named substance is calcedony or flint coloured by 
 a large proportion of peroxyde of iron. The brown Egyptian 
 pebbles are jasper: and bright red and yellow jasper intersected 
 bv slender veins of white quartz occurs in masses of great 
 extent in Sicily and the Apennines, besides many other locali- 
 ties. It is sometimes green and deep yellow. 
 
 Flinty slate or Lydian stone, the touchstone of the jewellers, 
 is a kind of flint containing carbonaceous matter : it forms 
 strata of small extent in limestone rocks. It is black, or dark 
 blackish green, and opaque. In order to ascertain the fineness 
 of gold, it is drawn across the stone, and the trace of metal is 
 assayed with acid. 
 
 2. OpalJ (Hydrate of Silica). 
 
 * The ancients gave this name to a stone which, as the name imports, 
 was of a golden green colour ( chrusos gold) : it is doubtful whether the 
 modern chrysoprase is the same substance. 
 
 f Pliny speaks of heliotrope as a stone that was used for solar observa- 
 tions : helios the sun, and trope a turning. 
 
 x Opal, from ops the eye : it was believed, anciently, to have the power 
 of strengthening the sight. 
 
OPAL. 
 
 41 
 
 Precious or noble opal . — This variety is the one most gene- 
 rally known ; its great beauty rendering it a valuable object of 
 research. 
 
 It is vitreous, transparent, and has a pale bluish or yellow- 
 ish tinge ; sometimes also it is milky and semi-transparent. 
 It exhibits the most brilliant colours in flashes and sparkles, 
 and sometimes the interior of the stone seems filled with 
 coloured light. It is rather less hard than quartz, and more 
 fragile, particularly when much veined with cracks. Specific 
 gravity 2*11 to 2*3. By calcination it gives off water, of 
 which it contains from 6 to 1 1 per cent. 
 
 Opal sometimes loses partly, or even entirely, its beautiful 
 play of colours, especially if kept in too warm a situation : this 
 is attributed to its losing some of the water essential to its 
 composition : from the same cause it sometimes falls to pieces. 
 The largest and finest specimens are brought from Kaschau in 
 Hungary, where small masses are embedded in a cellular por- 
 phyritic rock : they seldom exceed a nut in size ; but there is 
 a splendid specimen in the Imperial collection at Vienna, about 
 as large as a man’s fist, probably unique. It has been disco- 
 vered more recently at Honduras. 
 
 Fire opal (Girasol), a Mexican variety, of a dull yellow or 
 reddish colour, semi-transparent, which reflects in the interior 
 a bright red light. 
 
 Common opal . — It is so called, when transparent and vitreous, 
 without reflecting the brilliant colours of precious opal. 
 
 Semi-opal or pitch opal (Opale ferrugineuse ; Silex resinite ; 
 Jaspe-opale,) occurs of many shades of yellow and red, passing 
 even to dark brown tints, chiefly from the intermixture of 
 peroxyde of iron and alumina, which renders it opaque or 
 feebly translucent. The fracture of semi-opal is conchoidal 
 with a waxy or resinous lustre. It is less hard than quartz, 
 and more brittle; characters which, together with its lustre, 
 will distinguish it from jasper, with which, however, it appears 
 to be sometimes intermixed, passing into it by imperceptible 
 gradations. 
 
42 
 
 HYDROPHANE. 
 
 Cacholong* is a bluish-white translucent opal, having a 
 vitreous lustre, which is sometimes interstratified with calce- 
 dony. The exterior is often in a decomposing state, and is 
 then opaque, with a compact earthy fracture, and from its 
 strong disposition to absorb water will adhere slightly to the 
 tongue. 
 
 Hydrophane f belongs to this variety ; it is opaque and dull ; 
 but on being immersed in water it gradually becomes trans- 
 lucent, emitting streams of minute air-bubbles : some pieces, 
 after immersion, present the brilliant colours of precious opal. 
 
 Menilite , so named from its locality, Menil Montant, near 
 Paris, is of a dark liver colour, sometimes greenish, and occurs 
 in flattened reniform masses, which break with a somewhat 
 slaty structure, and but little lustre. 
 
 Siliceous sinter (Opale incrustante ; Tuf du Geyser) : this 
 is a deposition of opaline silica from the water of the boiling 
 springs in Iceland. It is usually of a light grey colour, and 
 varies much in its texture : specimens from the interior of the 
 basin are compact, with a glistening lustre, and appear strati- 
 fied, as if produced by successive depositions; those from 
 without the basin are generally porous, and inclose fragments 
 of grass and herbs : sometimes it consists of small rounded 
 pearly masses. 
 
 Hyalite (Muller’s Glass) occurs in small rounded masses, as 
 if dropped on the surface of the rock. 
 
 Silicates. 
 
 The genus silicate includes the greater part of the species 
 which form the crystalline and aggregated rocks : it also 
 comprises most of the minerals called precious stones , and of 
 those which on account of their hardness and beauty are well 
 adapted for onamental purposes. 
 
 Aluminous silicates, either simple or combined with silicates 
 
 * From the river Cach in India, 
 f Hudor , Gr., water, and ephane it shines. 
 
KYANITE — GRENATITE. 
 
 43 
 
 of other bases, are the most numerous, and the most abundant 
 of the species. 
 
 1. Kyanite (Disthkne, Sappare, Rhsetizite). 
 
 In the mica-schist of St. Gothard and some parts of the 
 Tyrol are found embedded crystals of this mineral : they are 
 prisms, having generally eight sides, rarely with any perfect 
 terminations, and cleavable with ease, parallel to the broader 
 faces of the prism. Kyanite is generally pale blue, sometimes 
 colourless ; transparent, with a somewhat pearly lustre, and 
 sufficiently hard to scratch quartz. Specific gravity 3*50. 
 Before the blowpipe, infusible. The variety called Rhsetizite 
 is radiated, and sometimes of a pale red or lilac colour. 
 
 This mineral contains about 36 per cent, of silica and 64 of 
 alumina — it is a subsilicate . It is often associated, in the same 
 rock, with small garnets and the following species. 
 
 2. Grenatite (Staurotide ; * Pierre de croix). 
 
 The crystals of grenatite, when black, are opaque ; but they 
 are often of a dark brownish-red colour, and translucent. 
 They are either rhombic prisms (obtuse angle 129° 20') or 
 hexagonal, and are frequently grouped so as to form a cross. 
 The fracture is vitreous, or 
 inclining to resinous. Spe- 
 cific gravity 3*2 to 39: 
 hardness, about the same as 
 of kyanite. It has never 
 been found massive, nor in 
 slender or radiated crystals. Grenatite consists of silica with 
 alumina and peroxyde of iron ; but the proportion of the two 
 latter, being isomorphous, varies in different specimens. 
 
 3. Sillim anite, a combination, in equal proportions, of 
 silica and alumina, which crystallizes in oblique rhombic 
 prisms of a grey colour, has been found only in Connecticut : 
 it is harder than quartz. 
 
 Porcelain Earth (Kaolin), a white earthy mineral of soft 
 fine texture, has nearly the same composition ; but from some 
 * Stauros, Gr., a cross — Grenatite, from its garnet colour. 
 
44 
 
 FULLERS’ EARTH — EMERALD. 
 
 localities it contains water. It proceeds from the decomposi- 
 tion of felspar, and in some granitic districts forms extensive 
 beds. Large quantities are obtained at St. Austle’s Moor in 
 Cornwall, for the use of the porcelain manufactories. 
 
 There are several species of silicate of alumina combined 
 with water, among which are 
 
 4. Fullers’ Earth (Terre a foulon), a soft earthy sub- 
 stance of a light brown or greenish grey colour : it falls to 
 pieces in water and readily mixes with it, but does not form a 
 plastic paste. 
 
 Cimolite , a reddish earth from the island of Cimola in 
 the Archipelago, is a similar substance, and used for the same 
 purposes. 
 
 Bol, of a bright red colour, which it owes to the peroxyde 
 of iron, and a paler sort obtained from Lemnos, which is 
 much esteemed in the East for its supposed medicinal virtues, 
 are nearly the same substance. 
 
 Kollyrite, halloysite, pholerite, lenzinite, and rock soap, so 
 called from its soft soapy texture, belong to this group of 
 species : they all consist of the same constituents ; silica, 
 alumina, and water, with small quantities of iron. They do 
 not crystallize, and afford water on being heated in a closed 
 tube. 
 
 Lithomarge, of a yellowish or reddish colour, is an earthy 
 substance, which is more abundant, particularly in Saxony, 
 where it fills veins, intermixed with topazes and quartz. 
 
 Silicates of Alumina with Glucina. 
 
 5. Emerald (Smaragd). 
 
 Beryl or aquamarine. 
 
 These two minerals are essentially the same substance, and 
 differ only in their colouring matter ; which in the emerald is 
 oxyde of chrome, and in the beryl, oxyde of iron. The crys- 
 tals of both are hexagonal prisms, sometimes modified, but 
 rarely with pyramidal terminations. The prisms of the beryl 
 are often rounded and deeply streaked laterally . Their hard- 
 ness is between 7 and 8, which is greater than that of rock 
 
EUCLASE CHRYSOBERYL. 
 
 45 
 
 crystal. When broken, the fracture is generally conchoidal 
 and perfectly vitreous. Composed of silica 68*3, alumina 
 17*60, glucina 13. The beautiful green of 
 the emerald is always the same, varying only 
 in depth : the beryl is sometimes greenish- 
 blue, sea-green, of different shades of yellow, 
 and occasionally almost colourless. Small 
 and moderate sized crystals are generally 
 transparent : the finest of these come from 
 Brazil and Siberia, where they are associated 
 with quartz and topazes. The opaque beryl is of a greenish 
 or yellowish white colour, and is found in crystals of immense 
 size. In North America prisms four feet in length are said to 
 be found embedded in granite and gneiss rocks ; the planes of 
 the prisms being five inches in width. In France, also, near 
 Limoges, they occur of very large size. Both varieties are 
 fusible by the blowpipe, but with some difficulty, into a frothy 
 glass. 
 
 6. Euclase,* a very rare mineral, containing 21 percent, 
 of glucina, has been found only in Brazil and Peru, in trans- 
 parent crystals of a pale bright green colour. Its form is an 
 oblique prism variously modified. Euclase is characterised bv 
 its great brittleness, the facility with which it becomes electric 
 by heat, and the length of time it retains this property. 
 These characters and its crystallization distinguish it from 
 beryl and from the following species. 
 
 7. Chrysoberyl (Cymophane; Oriental Chrysolite). 
 
 Its crystals, derived from a right rectangular prism, are 
 often much modified, and have a tabular appearance. In 
 Connecticut and other parts of the United States, they are 
 embedded along with beryls and garnets. In Brazil and 
 Ceylon they occur as rounded pebbles in the sand of rivers, 
 intermixed with zircons, spinel rubies, and other hard sub- 
 stances which have been washed out of the debris of rocks, 
 their original repository. 
 
 * Eu, Gr., easily, and clasis a fracture ; from its brittleness. 
 
 No. 32, 
 
46 
 
 GARNET. 
 
 The colour is a very pale green inclining to yellow, some- 
 times displaying in the interior a bluish floating light. On 
 account of its pleasing colour and great hardness it is em- 
 ployed in jewellery. Its specific gravity, which is 3*6 to 3*7 — 
 its greater hardness, which is above that of topaz — its com- 
 plete infusibility and its crystallization — distinguish it from the 
 two preceding species, and from topaz. It contains 15 or 16 
 per cent, of glucina. 
 
 Silicates of alumina with lime, iron, &c. 
 
 8. Garnet. 
 
 There are several kinds of garnet, differing from each other 
 in their colour and transparency, and even in their composi- 
 tion, yet having the same crystalline forms and nearly the 
 same hardness; and being all fusible by the blowpipe, and 
 insoluble, or with difficulty soluble, in acids. Most of the 
 varieties afford distinct cleavages parallel to the faces of a 
 rhomboidal dodecahedron, which is therefore to be considered 
 their primary form; their hardness varies from 7 to 7*5, and 
 specific gravity from 3*35 to 4*24. 
 
 Pyrope (Almandine ; Precious garnet) is of a crimson-red, 
 inclining to violet or to brown ; generally transparent, or 
 strongly translucent. Crystals, either simple dodecahedrons, 
 or with the edges replaced, or trapezohedrons (figs. 9, 18), 
 which are embedded in rocks, particularly those of the older 
 formations, where it also occurs in roundish grains. Fracture 
 vitreous, and generally conchoidal. Fused by the blowpipe, 
 it becomes a black globule, sometimes semi-metallic, and 
 attractable by the magnet. 
 
 Grossular.* This kind of garnet, which contains little or 
 no iron, is of a pale yellowish green, nearly opaque ; or trans- 
 parent and of a bright yellow or orange-colour (topazolite). 
 Colophonitef is a granular variety which occurs principally in 
 veins in Norway and Sweden ; and Cinnamonstone (Essonite) 
 resembles it very much in lustre and colour, but is found in 
 
 * Groseille, from its colour. 
 
 f Kolophonia (pix), resin ; from its colour and lustre. 
 
IDOCRASE. 47 
 
 larger fragments in Ceylon, where it forms part of an aggre- 
 gate rock. It is sometimes used in jewellery. 
 
 In the variety called aplome, the faces of the crystals are 
 striated parallel to the edges of a cube. 
 
 Melanite* and Pyreneite;\ black garnets. The former 
 occurs in the Vesuvian lavas and some calcareous rocks of 
 Norway; the latter in the Pyrenees. When fused by the 
 blowpipe they produce a black globule attractable by the 
 magnet. This kind is less hard than the preceding. 
 
 Mangcinesian garnet (Spessartine) is of a dull red or reddish- 
 brown colour : manganese, in this kind, replaces the iron. 
 Another variety (from Russia) derives a bright green colour 
 from the oxyde of chrome. 
 
 The pyrope or precious garnet is the same as the carbuncle 
 of the ancients : the finest are now obtained from Bohemia 
 and Greenland. Garnets frequently occur in metalliferous 
 veins, and small ones have been found in Cornwall. 
 
 9. Idocrase J (Vesuvian; Baikalite ; Acanticone). This 
 mineral does not differ much in composition from some of the 
 garnets, consisting of silica, alumina, and lime, with some 
 protoxyde of iron ; but its crystals are derived from a square 
 prism. In hardness it is scarcely equal to quartz, and its 
 specific gravity is 3, or 3*4. The prisms are generally modi- 
 fied on all the edges, and often on the angles (fig. 24) ; those 
 which are of a clear olive-green colour are generally trans- 
 parent, and sometimes very brilliant ; the dark green ones are 
 mostly opaque. Fine crystals are obtained from the vicinity 
 of Lake Baikal ; and it is abundant in the lavas and crystalline 
 rocks ejected from Vesuvius, both green and of a dull garnet 
 colour, intermixed with mica and sommite. Fusible into a bead 
 of yellowish glass, transparent or translucent. Most varieties 
 are soluble in the acids more readily than the garnets. 
 
 * Melas, Gr., black. 
 
 f Pyreneite, found in the Pic Eredlitz of the Pyrenees. 
 
 t Eido3, Gr., a form, and tcrasis a mixture — signifying a mixed form ; 
 because it resembles several other species in its crystallization. 
 
48 
 
 SCAPOLITE — EPIDOTE. 
 
 10. Scapolite (Wernerite ; Arctizite ; Paranthine). 
 
 A mineral which is very abundant in some parts of Sweden 
 and Norway in the great tracts of iron ore, where it is often 
 intermixed with garnets, epidote, and some other substances. 
 Its colour is pale grey or greenish grey, and it occurs in 
 slender square prisms either embedded in limestone or in 
 separate groups. Hardness, rather less than that of felspar, 
 5*5; specific gravity 2*5 to 2*7 ; fusible with difficulty. It 
 has been found in North America, but not in Great Britain. 
 
 The small limpid crystals called meionite, which are found 
 in some lavas and in the dolomite of Vesuvius, appear to 
 belong to the same species : their form, hardness, and specific 
 gravity are the same ; both consist of silicate of alumina with 
 silicate of lime. 
 
 Thulite , which is of a rose colour, is very similar in compo- 
 sition ; it is found at Tellemarken, in Norway. 
 
 Gehlenite, another variety, containing more lime, occurs in 
 the Tyrol : infusible. 
 
 11. Epidote* (Thallite ; Pistacite ; Arendahlite). 
 
 This mineral crystallizes in modified rhomboidal prisms, 
 which have an unsymmetrical appearance, from the base of the 
 primary being an oblique-angied parallelogram ; they are 
 referable to the fifth series of solids. The coiour is generally 
 a rich yellow green ; varying from transparent, in small bright 
 vitreous crystals, to opaque in granular masses, or when it is 
 disseminated in rocks. Hardness varying from 6 to 7 ; brit- 
 tle ; specific gravity 3*2 to 3*46. Very large crystals are 
 obtained from the granitic rocks of Norway and Sweden ; 
 and beautiful specimens, chiefly of small groups of crystals 
 associated with felspar, from Dauphine and the Valley of 
 Chamouni. 
 
 Epidote contains 38 parts of silica, 27 of alumina, with lime 
 and protoxyde of iron. 
 
 * It received the name Thallite from Thallos , Gr., the bud of the olive 
 tree, from its colour ; Pistacite from the pistachio nut, also from its colour; 
 arendahlite from Arendahl in Norway. 
 
ZOISITE IOLITE. 
 
 49 
 
 Zoisite is considered to be a variety of the same species, in 
 which the protoxyde of iron is replaced by lime. It is gene- 
 rally of a light grey colour, opaque, rarely crystallized, but 
 cleavable in two directions. 
 
 Both kinds, when exposed to the action of the blowpipe, 
 exfoliate , or separate into laminae in the direction of the cleav- 
 ages ; but melt only on the edges. 
 
 Manganesian Epidote is a variety of a purplish-brown colour, 
 peculiar to St. Marcel, in Piedmont, occurring in manganesian 
 ores. 
 
 12. Iclite (Dichro'ite ; Indicolite; Cordierite ; Peleom; 
 Steinheilite). 
 
 The property of dichro'ism was first observed in this mineral ; 
 and as it was then thought to be peculiar to it, it obtained the 
 name dichro'ite. It is rarely crystallized in six and twelve 
 sided prisms ; generally disseminated in small masses of irre- 
 gular form, which are of a deep violet-blue colour when viewed 
 parallel to the axis of crystallization ; but in a contrary direc- 
 tion they appear yellowish or smoky grey. In its fracture 
 and lustre, it perfectly resembles glass, but is rather harder 
 than quartz. Differs from all the preceding species in con- 
 taining 10 per cent, of magnesia. 
 
 When sufficiently transparent and of a good colour, it is 
 sometimes used in jewellery, under the name of water sap- 
 phire . Found principally at Bodenmais in Bavaria; also in 
 Sweden. 
 
 Silicates of alumina with an alkali or alkaline earth. 
 
 13. Felspar (Felspath ; Adularia; Orthose*). 
 
 This is a mineral of considerable importance, from its exten- 
 sive distribution, and the variety it displays in its colour, crys- 
 tallization, and modes of occurrence. As a constituent of 
 granite it has a perfectly crystalline structure : as the base of 
 porphyries it is compact, of a close, even texture. In granite, 
 the crystals of felspar form groups in cavities or veins, often 
 
 * From Orthos , Gr., right or straight. 
 
 D 
 
50 
 
 FELSPAR. 
 
 with other crystallized substances : in porphyry the crystals 
 are embedded separately, as in a paste. 
 
 The crystals are derived from a symmetrical oblique rhombic 
 prism, obtuse angle 119°, and 
 yield to cleavage with facility, 
 parallel to its bases and to a 
 plane passing through the short- 
 er diagonal, which is perpendi- 
 cular to them (No. 33.) It is 
 important to remember this cir- 
 cumstance, because the right- 
 angled cleavage distinguishes felspar from albite, which other- 
 wise resembles it in most particulars, and was long considered 
 to be the same substance. 
 
 The macled crystals of felspar, which are of frequent occur- 
 rence, do not offer the re-entering angles which we find in the 
 hemitropes of most substances; this is a consequence of the 
 right-angled cleavage, the plane of junction being that which 
 passes through the diagonals. Its most common colours are 
 yellowish and greyish-white, and various shades of flesh-red 
 and brick-red : lustre of the fracture, bright and vitreous : 
 crystals externally from shining to dull. Specific gravity 2*39 
 to 2*6. Hardness 6. In this character it is very constant. 
 Insoluble in acids, and scarcely fusible by the blowpipe, except 
 on the edges ; but with borax it forms a colourless glass. In 
 the transparent colourless varieties, called adularia, a bluish 
 opalescent light is often visible, and small pieces, cut and 
 polished, are sold under the name of moonstone . Fine speci- 
 mens of this kind are brought from Mount St. Gothard ; and 
 very perfect opaque crystals from Baveno in Piedmont, and 
 Chudleigh in Devonshire. Composed of silica 64*20, alumina 
 18*40, potash 16*95. Compact felspar, in some of the antique 
 porphyry, is of a green colour; in other varieties, of a dark 
 garnet-red. 
 
 Large quantities are used in the manufacture of porcelain, 
 as well as of the decomposed felspar (kaolin). 
 
 No. 33. 
 
 No. 34. 
 
ALBITE — LAB RADO RITE ANDALUSITE. 
 
 51 
 
 14. Albite* (Cleavelandite ; soda felspar) differs from fel- 
 spar in containing 10 to 12 per cent, of soda, in place of the 
 potash which is a constituent of the former ; and in its crystal- 
 lizations, which belong to the sixth series of solids ; the three 
 cleavages all meeting at oblique angles. Yet the general 
 appearance of albite and felspar is so similar, that it is often 
 difficult to distinguish them ; their hardness is equal, and their 
 chemical characters the same, except that albite gives a yellow 
 tinge to the blowpipe flame. It forms the basis of granite in 
 several countries, particularly in North America, and is charac- 
 terised by its almost constant whiteness : the crystals also are 
 generally more tabular, and, when macled, have re-entering 
 angles. The bright transparent crystals generally called glassy 
 felspar , which are embedded in some porphyritic rocks and 
 lavas, belong to this species. 
 
 Anorthite , which occurs crystallized in some lavas, is nearly 
 allied to albite, but contains lime instead of soda ; in which it 
 resembles indianite, a mineral of a crystalline granular struc- 
 ture from the Carnatic. 
 
 14. Labradorite, a kind of felspar that contains both lime 
 and 4 per cent, of soda, is characterised by the brilliant colours 
 it reflects in certain positions, particularly shades of green and 
 blue : independently of these, its general colour is dark grey. 
 It is rather less infusible than felspar and albite, and may be 
 dissolved in hydrochloric (muriatic) acid. 
 
 In Labrador it is found in large masses, and is said to 
 abound in the state of New York. 
 
 15. Andalusite (Felspath Apyre ; Made; Chiastolite). 
 
 A very hard mineral, which, at first sight, appears to resem- 
 ble some felspars : but it crystallizes in prisms which are very 
 nearly square. It is generally of a pearly grey, but sometimes 
 of a rose colour ; faintly tanslucent, and breaking with a fine- 
 grained fracture, but scarcely any lustre. In hardness, inter- 
 mediate between quartz and topaz : specific gravity 3*1 to 3*3 ; 
 in these two characters, and in its crystallization, it differs 
 * Aldus , white. 
 
 n 2 
 
52 
 
 NEPHELINE — SPODUMEN. 
 
 from felspar. It was first brought from Andalusia, but has 
 since been found in several other places ; the crystals are 
 sometimes enveloped in scales of mica. 
 
 The variety named chiastolite presents a singular structure : 
 the crystals, which are nearly white, and 
 opaque, appear to include, in the centre 
 and at the angles, similar prisms of a dark 
 substance, which is considered to be the 
 same in which they are embedded. Small 
 crystals of this kind are disseminated in 
 the slate of Skiddaw. 
 
 16. Nepheline (Sommite; Icespar). 
 
 A white or yellowish-white semi-transparent mineral which 
 
 abounds in the Vesuvian lavas, intermixed with idocrase, mica, 
 and other substances. Crystallizes in hexagonal prisms, which 
 are often tabular. Rather less hard than felspar. 
 
 Elaolite* (fatstone), a greyish or bluish-green mineral with 
 an oily lustre, which is embedded in the syenite of Norway, 
 appears to be the same substance. 
 
 Gieseckite and Finite of Auvergne , which also crystallize in 
 6 and 1 2-sided prisms, belong to the same group : the latter 
 contain potash ; the two former, soda. 
 
 17. Spodumen (Triphane ; Killinite). 
 
 This mineral, as well as the following one, contains the 
 alkali lithia 3 which is detected by exposing them with soda to 
 the action of the blowpipe, on a support of platinum foil : the 
 flame will be tinged red, and a brown stain will remain on the 
 platinum. 
 
 Its colour is gr^en, or greenish-grey ; lustre, pearly or oily; 
 cleavable parallel to the planes of a rhombic prism of 100° and 
 80°; specific gravity 3*19; in hardness, intermediate between 
 felspar and quartz. It is abundantly disseminated in the 
 granitic rocks of Sudermania. It differs from felspar and 
 scapolite in chemical characters, specific gravity, and angles of 
 cleavage. 
 
 * Elacon, Gr., oil. 
 
PETALITE — OBSIDIAN. 
 
 53 
 
 18. Petalite (Berzelite; Arfwedsonite) contains more silica 
 and less alumina than the preceding species. When gently 
 heated it becomes phosphorescent, and may with some diffi- 
 culty be fused; colour white or very pale grey. 
 
 19. Obsidian (Volcanic glass ; Marekanite). 
 
 This is a black glassy substance, breaking with a large per- 
 fect conchoidal fracture ; opaque or slightly translucent on the 
 edges of fragments. On being exposed to the action of the 
 blowpipe, it swells and froths considerably, and is reduced 
 finally to a white enamel. The composition of this species 
 varies : some specimens afford soda, and others potash ; they 
 contain 72 to 78 per cent, of silica. 
 
 In Mexico, where it is abundant, and was formerly used for 
 knives and mirrors, a variety is found which reflects a chatoy- 
 ant light of a dark bronze colour. Obsidian is sometimes met 
 with, also, among the ejected matters of modern volcanos. Its 
 chemical properties and the total absence of crystallization 
 distinguish it from smoky quartz. 
 
 Pitchstone (Retinite) is less vitreous than obsidian, and the 
 conchoidal fracture less bright and perfect : the lustre is resin- 
 ous, or resembling that of pitch. It presents many colours, 
 principally deep dull greens, brownish red and ochre yellow of 
 different shades ; sometimes small bright specks of crystalline 
 felspar are scattered though it. The red and yellow varieties 
 have a great resemblance to semi-opal (ferruginous opal), but 
 may be distinguished from it by not affording water when 
 heated, and by frothing and melting in much the same manner 
 as obsidian. Abundant in some parts of Saxony, Hungary, 
 and the Isle of Arran, besides other localities. 
 
 Pearlstone (Perlite) differs little in its composition from 
 pitchstone ; it consists of rounded angular grains, closely 
 pressed together, generally of a light grey colour, and rather 
 pearly. In spherulite the grains are globular, and are some- 
 times embedded in obsidian. 
 
 Pumice (Ponce) is another substance belonging to this group, 
 which is more abundant among the productions of recent vol- 
 
54 
 
 LEUCITE — PAGODITE — CHLORITE. 
 
 canos, as the two former are among those of extinct or ancient 
 ones. It appears to be the scum or froth of lava, suddenly 
 cooled by ejection, so as to preserve its spongy form ; and is 
 so porous as to float on water. Sometimes, the pores being 
 elongated, it has a fibrous structure. In composition it ap- 
 proaches very nearly to felspar. Being hard and easily reduced 
 to powder, it is much employed for polishing marble, glass, 
 metal, wood, and other materials. 
 
 20. Leucite (A mphigene; White garnet). 
 
 This mineral is common both in ancient and modem lava, in 
 which it is scattered in trapezohedral crystals of a dirty-white 
 colour, usually opaque or translucent, and with a dull surface : 
 internally vitreous ; scarcely so hard as felspar. It contains 
 22 per cent, of potash, but is infusible. 
 
 21. Pagodite (Agalmatolite ; Figurestone). 
 
 A great part of the images and other carvings that come 
 from China are executed in this stone, which is so soft and 
 unctuous that it resembles, in texture, a compact talc or ste- 
 atite. 
 
 It is opaque, generally reddish or greyish- white, sometimes 
 veined with a deeper tint, with a feebly oily lustre. When 
 heated, it becomes harder, shining, and scaly, but is infusible. 
 Consists of silica 54, alumina 34, potash 6’2, water 4. 
 
 22. Chlorite. 
 
 A dark or blackish-green mineral, widely distributed in rocks 
 of the ancient formations, where it forms veins and small beds : 
 in the latter case it has a slaty structure, and is tolerably com- 
 pact ; in the former it is earthy and granular, or composed of 
 minute scales. It is very common in the tin veins of Cornwall, 
 and in similar deposits of ore in other countries. It is often 
 found coating the crystals of quartz, adularia, &c., or in the 
 interior of these substances, resembling moss. Sometimes, 
 but rarely, crystallized in hexagonal plates. 
 
 Its composition varies very much : but it consists principally 
 of silica, alumina, protoxyde of iron and water, sometimes with 
 magnesia, sometimes with potash. 
 
GREEN EARTH — ZEOLITES. 
 
 55 
 
 23. Green earth. 
 
 The minerals thus designated have generally a much brighter 
 colour than chlorite, and never exhibit any trace of crystalliza- 
 tion. They all contain water and protoxyde of iron ; but the 
 quantity of alumina varies so much, that very different sub- 
 stances appear to be included under the same name. 
 
 Terra verte , which is much employed as a pigment, occurs in 
 cavities in amygdaloidal rocks; sometimes, as in the neighbour- 
 hood of Verona, in considerable masses; sometimes it only lines 
 the cavities, the interior being filled by zeolitic or other minerals. 
 
 Zeolites. 
 
 The following species, from Natrolite to Prehnite, include 
 those substances which are usually termed zeolites ; and which, 
 from a resemblance in several of their characters, have been 
 generally placed in the same family or genus. They consist 
 principally of silica, alumina, water, and either some alkali or 
 an alkaline earth. They all afford water on being heated; most 
 of them dissolve in acids and form a gelatine; and the greater 
 part, when heated by the blowpipe, froth and boil violently. 
 
 24. Natrolite 1 (Mesotype ; Radiated Zeolite ; Needle 
 
 25. Skolesite / Zeolite). 
 
 These two species resemble each other so nearly, that they 
 were long confounded together under the name of mesotype . 
 The crystals of both are aci- 
 cular, or needle shaped , and 
 usually grouped in divergent 
 tufts: those of skolesite are 
 square prisms, those of na- 
 trolite, rhombic ; but the 
 difference of their angles is 
 so small as to be impercep- 
 tible to the unassisted eye. 
 
 They are colourless and 
 transparent, and when perfect are terminated by four or six 
 planes ; but both substances occur in small masses, having a 
 radiated structure and a beautiful pearly lustre. 
 
 No. 36. 
 
56 
 
 ZEOLITES. 
 
 NO. 37. 
 
 Natrolite forms also botryoidal masses composed of delicate 
 fibres, radiating from several centres : this variety is sometimes 
 red, or of a fine orange colour. Both species gelatinize when 
 dissolved in acids: natrolite contains soda;* skolesite, lime : 
 the latter may be distinguished by its twisting and curling 
 like a wormf before the blowpipe. 
 
 Thomsonite is very similar to the preceding species, but its 
 prisms are rectangular, and in general it is less transparent ; 
 sometimes massive. 
 
 26. Stilbite J (Foliated Zeolite). 
 
 This is a very beautiful substance, and offers considerable 
 variety in its appearance ; but is always charac- 
 terised by a brilliant pearly lustre. The crystals, 
 which are often hexagonal and very thin, are mo- 
 dified rectangular prisms : sometimes it is massive, 
 or appears in large rhombic prisms, but always 
 exhibits one distinct cleavage : in this it resembles 
 selenite (which will be described hereafter), but is 
 very much harder, about 4. 
 
 Stilbite exfoliates before the blowpipe, and afterwards boils 
 and fuses into a glassy substance. 
 
 27. Heulandite, when massive, is very much like stilbite, 
 but usually of a red colour : its crystals are modified rhombic 
 prisms, and are not generally so thin as those of stilbite. 
 
 Brewsterite y like the preceding, but generally colourless, and 
 contains a little soda. 
 
 28. Harmotome (Cross-stone; White hyacinth). No. 38. 
 
 Differs in composition from the other zeolites, 
 
 in containing 17 or 18 per cent, of the earth 
 baryta : and its crystals, which are modified rect- 
 angular prisms, often occur in groups, so arranged 
 as to form a cross. The crystals are always 
 white, and generally translucent. Specific gra- 
 vity 2*3 or 2*4, which is a little higher than that of the 
 
 * Formerly Natron, whence the name. f Skolex , Gr., a worm. 
 
 X Stilbe, Gr., splendour. 
 
 fh 
 
ZEOLITES. 
 
 57 
 
 preceding minerals. When heated it becomes phosphorescent, 
 and fuses without ebullition. 
 
 Phillipsite (Abrazite : Gismondine), which occurs in crystal- 
 lizations precisely similar, in some Vesuvian lavas, differs from 
 harmotome in containing lime in place of baryta. 
 
 29. Laumonite. 
 
 This is a rare substance which has been found in the lead 
 mines of Huelgoet in Brittany. It has been called efflorescent 
 zeolite from the alteration it undergoes when exposed to the 
 air; becoming opaque, and, in a short time, falling to pieces. 
 In order to prevent this change, the specimens should, as soon 
 as possible, be dipped into a solution of gum-arabic, and per- 
 fectly dried. It is white, cleavable into oblique rhombic prisms, 
 but very fragile. 
 
 30. Analcime (Cubicite; Sarcolite). 
 
 Crystallized in trapezohedrons, or cubes which are modified 
 on the angles (PI. figs. 17, 18). The crystals vary from the 
 size of a pin’s head to two or three inches in diameter : small 
 ones are brilliant and transparent; large ones often opaque and 
 reddish. When viewed in polarized light, the trapezohedral 
 crystals exhibit a singular arrangement of lines of prismatic 
 colours. It is easily fused, a circumstance which will distin- 
 guish it from leucite. 
 
 31. Chabasite (Chabasie) occurs crystallized in rhombo- 
 hedrons that are slightly obtuse, sometimes modified on the 
 terminal edges ; transparent, colourless, and generally brilliant. 
 
 Like Cubasite it is never massive nor fibrous. 
 
 32. Prehnite (Koupholite). 
 
 Crystallized prehnite is of rare occurrence. It is sometimes 
 found in thin rhombic or hexagonal plates ; but more often 
 massive, imperfectly crystallized on the exterior ; or in small 
 lens-shaped masses heaped together : compact, and sometimes 
 fibrous ; the fracture has scarcely any lustre. Its most usual 
 colour is sea-green. Hardness little inferior to that of quartz, 
 and specific gravity 2*8 to 3*; in both these characters it 
 exceeds considerably the other zeolites. In China it is cut 
 
 d 5 
 
58 
 
 TOPAZ. 
 
 into slabs for ornament, and carved into imnges which are 
 brought to Europe under the name of Oriental Jade . 
 
 The basalt rocks, and others of an igneous origin which are 
 called amygdaloidal , are the principal repositories of all this 
 group of species. The cavities of these rocks are sometimes 
 entirely filled by zeolitic substances ; others contain radiations 
 or groups of crystals, together with crystals of calcspar, but 
 rarely those of quartz. The Ferroe Isles and Staffa, in parti- 
 cular, afford fine specimens; but harmotome and prehnite 
 occur also in other situations. 
 
 Silicates of alumina with fluorine. 
 
 There are a few siliceous minerals in which fluorine is com- 
 bined : the most important are Topaz and Mica. 
 
 33. Topaz. 
 
 This is a well-known precious stone, which for ornamental 
 purposes is obtained chiefly from Brazil. It occurs there of 
 various shades of yellow and red, also colourless, and pale blue 
 and green. It is always crystallized, or in rounded pebbles. 
 The crystals are derived from a right rhombic prism, and are 
 generally well formed. In different localities, they generally 
 present different modifications which are peculiar to them : 
 thus, in Siberia, the crystals are usually characterised by two 
 terminal faces, larger than the 
 others, No. 39 ; the Saxon to- 
 
 No. i 
 
 19. 
 
 No. 40. 
 
 pazes have a plane parallel to the 
 base. No. 40; and those from 
 Brazil are mostly terminated by 
 a four-sided pyramid. The sides 
 of the prism are often streaked 
 lengthwise, like those of the be- 
 ryl ; but the topaz may be distinguished by its greater hard- 
 ness = 8, and by its very perfect and brilliant cleavage parallel 
 to the base : it is also heavier — specific gravity 3’49 to 3‘54, 
 and much colder to the touch. It contains 7 or 8 per cent, of 
 fluoric acid. The topaz is generally met with in the cavities 
 and veins of granite rocks. Splendid groups of crystals are 
 
MICA. 
 
 59 
 
 obtained from Siberia, intermixed with crystals of quartz, and 
 sometimes of beryl. In Saxony, Bohemia, and Cornwall, 
 crystallized topazes are found in the metalliferous veins, parti- 
 cularly those which afford tin ore, intermixed with fluor. 
 
 The ancients were well acquainted with this gem. It is said 
 that they first found it in an island of the Red Sea ; and as it 
 was often concealed by fogs, and difficult to find, they gave it 
 the name topazion, from topazo , to seek. 
 
 Some of the yellow Brazilian topazes, when heated with 
 proper care, acquire a beautiful rose colour ; but they are said 
 to lose this tint after some length of time. Of its natural 
 colours, the ruby tint is the most rare. 
 
 Pyrophysalite is an opaque variety of topaz with a coarse 
 texture, which, like the opaque beryl, occurs in crystals of 
 immense size. One taken from a granite quarry at Finbo, in 
 Sweden, which is preserved at Stockholm, weighs 80 pounds. 
 
 Pycnite differs but a little from topaz in the proportion of 
 its constituents : it is of a pale straw colour mixed with lilac, 
 and forms columnar masses embedded in quartz, at Altenberg, 
 in Saxony. 
 
 34. Mica* (erroneously Muscovy talc ; Muscovy glass). 
 
 Mica is a widely distributed mineral ; being, like quartz and 
 felspar, a constituent of granite and mica schist, besides its 
 frequent occurrence in other situations. In these rocks we 
 usually see it dispersed in little silvery scales, sometimes very 
 minute ; but in the granite of Siberia, and some parts of the 
 United States, transparent plates of mica are obtained from 
 two to three feet in diameter. These plates, if perfect, are 
 either rhombic or hexagonal; and the remarkably perfect 
 cleavage that all varieties of mica possess, is parallel to the 
 base of the crystals.^ 
 
 * Micare, to shine or glitter. 
 
 f Optical investigations show that there are at least three species of 
 mica : the hexagonal plates of some micas are primary crystals ; this kind 
 has been distinguished as hexagonal mica . In other specimens, the hexa- 
 gonal prisms are derived from a rhombic one, the two acute edges being 
 
60 
 
 TOURMALINE. 
 
 Its most common colours are light grey, brown, and olive 
 green ; but it is found occasionally black, deep blood-red, and 
 of a bright golden yellow. 
 
 Mica being very elastic and capable of being split into plates 
 of any thinness, it has been much employed in place of glass 
 for lanterns ; in Siberia and the Russian navy for windows : 
 and as it will bear considerable beat without injury or altera- 
 tion, it is often used for the doors of stoves and furnaces ; on 
 exposure to a greater heat it becomes opaque and white. 
 
 Lepidolite is of a lilac colour, massive, and consisting of 
 small aggregated scales. 
 
 Silicates containing boracic acid. 
 
 35. Tourmaline (Schorl; Rubellite). The crystals of tour- 
 maline are generally prismatic with 6, 9, or 12 sides; often 
 somewdiat triangular, but rounded and deeply grooved, late- 
 rally : perfect terminations are rare, and when they occur the 
 two ends are differently modified. The primary form is a very 
 
 No. 41. No. 42. 
 
 obtuse rhombohedron. It is of various colours : the black 
 variety (schorl), is perfectly opaque; blue, green, and brown 
 shades are more or less transparent : the rose-coloured has 
 been called rubellite . In Massachusetts an interesting variety 
 occurs, of a dark green externally, and the interior of a bright 
 rose colour. Acicular v crystals, both black and brown, are 
 sometimes found in radiated tufts, occasionally penetrating 
 other substances. 
 
 replaced ; and, in a third kind, the prisms are oblique. The composition 
 of mica is also variable ; some specimens contain potash, some lithia ; and 
 the quantity of fluoric acid varies from 2 to 8 per cent. 
 
AXINITE — LAPIS LAZULI. 
 
 61 
 
 The tourmaline is distinguished from all substances which, 
 in other respects, it resembles, by the facility with which it 
 becomes electric when heated, exhibiting polarity ; and by its 
 remarkable effects on light. A crystal which appears perfectly 
 transparent on looking through it across the prism , when held 
 between the eye and the light, and viewed in the direction of 
 the axis , will allow but a small quantity of light to pass through 
 it, and in many cases will be found opaque. 
 
 Very fine crystals of black tourmaline have been obtained 
 near Chudleigh ; they are some inches in length, with brilliant 
 faces. It is very widely distributed, being found in Brazil (of 
 various colours), Ceylon, Siberia (rubellite), the Alps (bright 
 green). North America, &c. The quantity of boracic acid is 
 variable. 
 
 36. Axinite* (Violet schorl ; Thumerstein). The peculiar 
 acute-edged form of its bright glassy crystals distinguishes 
 this mineral from most others. It is of a pale clove- 
 brown, inclining to purple, and transparent, unless 
 when intermixed with chlorite, which often pene- 
 trates or coats the crystals, rendering them green 
 and opaque. Hardness, barely equal to that of 
 quartz. It is fusible without much difficulty into a 
 dark green glass, which, in the oxydating flame, 
 becomes black. The finest specimens are brought from St. 
 Cristophe, in Dauphine. 
 
 Silicates containing sulphur or sulphuric acid. 
 
 37. Lapis lazuli (Lazulite). From this mineral the ultra- 
 marine blue is prepared. It has generally a fine granular tex- 
 ture, and occurs intermixed with granular limestone and pyrites, 
 filling small veins and cavities in granitic rocks, in Persia, 
 Thibet, and Bucharia. It is sometimes, but very rarely, crys- 
 tallized in rhombic dodecahedrons ; feebly translucent, and 
 having scarcely any lustre ; hardness 5 ’5 ; specific gravity 2*5 
 to 2*9. Soluble in acids, losing, at the same time, its colour, 
 which it is conjectured may be due to some combination of 
 
 * From the axe -shaped crystals. 
 
 No. 43. 
 
62 
 
 ZIRCON. 
 
 sulphur with the base of alumina : it loses its colour also by 
 fusion ; contains 23 per cent, of soda. 
 
 Hauyine . A blue mineral which is found embedded in some 
 ancient lavas near the Rhine, and appears to have some analogy 
 with the preceding species. 
 
 Hitherto we have described siliceous minerals of which alu- 
 mina forms an important constituent : we shall now speak of 
 those in which silica is united with other bases. 
 
 The earth zirconia is found in the state of silicate, and com- 
 bined, in a few rare minerals, with other substances. 
 
 38. Zircon (Zirconite; Hyacinth; Jargoon). The crystals 
 of this substance are derived from a square prism, and are 
 terminated usually by pyramids, which correspond sometimes 
 with the faces of the prism, sometimes with the edges (PI. fig. 
 20, 22, 23). Its specific gravity is 4*4, considerably higher 
 than that of most earthy minerals ; hardness, between that of 
 quartz and topaz ; lustre oily, approaching to adamantine. 
 The colour of zircon varies through shades of brownish-red 
 and garnet-red to pale yellow, grey and white in the transparent 
 varieties : these are brought chiefly from Ceylon and Pegu, 
 and are used in jewellery under the names of hyacinth and jar - 
 goon t but are not much valued. They are generally small, and 
 are found in the sand of rivers, and more or less rounded. In 
 this manner they occur at Expailly, near the Puy de Dome, in 
 France. The crystals embedded in the syenite of Norway are 
 much larger, sometimes above an inch in length: they are 
 generally dark-red brown, but not transparent. 
 
 Zircon, when heated by the blowpipe, loses its colour, but 
 is infusible alone, and even with soda is fused with difficulty. 
 This character, and its high specific gravity, will distinguish it 
 from the garnet, grenatite, and other minerals. 
 
 Eudyalite , a rare mineral from Greenland, contains zirconia, 
 with silica and soda ; its colour is reddish lilac. 
 
 39. Thorite is a hydrous silicate of thorina, which has 
 
CERITE WOLLASTONITE. 
 
 63 
 
 been found only in the Isle of Loeeven, on the coast of 
 Norway : it is black, vitreous, and hard enough to scratch 
 glass. 
 
 40. Gadolinite is a silicate of yttria, an earth which was 
 first discovered in this mineral, and named from its locality, 
 Ytterby, near Fahlun, in Sweden. It is black or brownish- 
 black, vitreous, and fusible into an opaque glass. 
 
 The minerals containing cerium are few and rare, they are 
 found in granite rocks in Sweden and Greenland. 
 
 41. Cerite (Cererite) is of a violet or rose colour, much 
 intermixed with grey or brown. It is compact, or fine 
 granular, and opaque. Specific gravity 4*93; infusible alone. 
 It contains 67 per cent of cerium, and 12 of water, with 18 of 
 silica, and 4 of lime and oxyde of iron. 
 
 Cerine contains a large proportion of iron, but no water. 
 
 Allanite and orthite have nearly the same composition ; 
 they are brownish-black, and are embedded in small acicular 
 or columnar masses, sometimes many inches in length. 
 Pyrorthite contains carbonaceous matter, which causes it to 
 burn when heated by the blowpipe. 
 
 Calcareous Silicates. 
 
 42. Wollastonite (Tablespar), and 43. Edelforsite, are 
 nearly pure silicates of lime, white or yellowish and trans- 
 lucent : the former (which contains less silica than the latter) 
 has some resemblance to felspar ; but may be distinguished by 
 its inferior hardness, and by having no right-angled cleavage. 
 It is found in several localities intermixed with garnets, tre- 
 molite, copper pyrites, and sometimes other substances. 
 
 44. Apophyllite (Fisheye- stone). The white, pearly crys- 
 tals of this mineral might, at first sight, be mistaken for those 
 of zeolite, but they are square prisms, either perfect or having 
 the angles replaced by triangular planes, which are sometimes 
 increased so as to produce a pyramid. It is also rather 
 harder than the zeolites, though scratched by felspar ; froths 
 before the blowpipe, and gelatinizes in acid. It is a silicate of 
 
64 
 
 CH RYSOLITE — CHONDRODITE TALC. 
 
 lime and potash, with water, and occurs both in the same 
 situations as stilbite, &c., and in the neighbourhood of the 
 great deposits of magnetic iron in Sweden and Norway. 
 
 Magnesian Silicates. 
 
 These, when not combined with lime, are characterised by 
 great infusibility, are very difficultly soluble in acids, and many 
 of them are very soft and unctuous. 
 
 45. Chrysolite (Peridot ; Olivine). A gem of a yellowish- 
 green colour, sometimes passing to a pale yellow-brown, 
 which is disseminated in some basaltic rocks in small trans- 
 parent grains, and more rarely in crystals, which are modified 
 rectangular prisms. It breaks with a vitreous fracture, is 
 scarcely so hard as quartz, and infusible without the addition 
 of a flux : these two characters distinguish it from the beryl 
 and chrysoberyl. It is a silicate of magnesia and iron. The 
 vitreous grains observed in basalt were named olivine from 
 their colour, before it was known that they were the same 
 substance as chrysolite ; in some of these formations, it occurs 
 in granular masses of considerable size, as at Vivarais, and the 
 banks of the Rhine. But the most remarkable situation in 
 which chrysolite has been found, is in the cavities of the cele- 
 brated mass of meteoric iron in Siberia, and it is now ascer- 
 tained that it forms a large proportion of some other masses 
 which are derived from the same source. 
 
 The finest chrysolites are brought from Constantinople, cut 
 and polished, and it is not known in Europe, whence they are 
 originally obtained. 
 
 46. Chondrodite (Brucite). A silicate of magnesia, con- 
 taining fluoric acid, which is found in translucent grains of a 
 yellowish or brownish colour, at Pargas (Finland) and New 
 Jersey (United States), embedded in limestone. 
 
 47. Talc generally occurs in foliated masses, white, or of 
 some shade of green, having a very pearly lustre. The folia 
 have no regular form, but are often divergent or stellated. 
 Talc, though flexible, is not elastic, which is a distinction 
 
STEATITE — POTSTONE. 
 
 65 
 
 between it and mica ; the laminae are also much more tender 
 than those of mica, being easily scratched by the nail (No. 1, 
 in the scale of hardness), and it is soft and unctuous to the 
 touch. Talc is a silicate of magnesia, combined sometimes 
 with hydrate of magnesia in variable quantity. 
 
 The finest specimens are obtained from the Alps of Savoy 
 and Piedmont. It is said also to have been found in the 
 United States of a rose colour, and blue. 
 
 French chalk is a variety of talc in which the folia are so 
 small that it has a somewhat granular texture and a glim- 
 mering lustre. 
 
 Steatite or soapstone has the same composition ; it has a 
 more compact and earthy appearance than French chalk, and 
 a very soapy or unctuous feel. It forms veins in serpentine, 
 and is quarried and applied to many purposes ; as, in mixing 
 with clay, &c., for the manufacture of porcelain, of which it 
 increases the transparency, and, in powder, for diminishing 
 the friction of machinery. Pencils also are made of it, instead 
 of slate ; and it is very efficacious in removing spots of 
 grease from silk and cloth. In France it is called Craie de 
 Briancon. 
 
 Potstone (Pierre ollaire) is of a dark grey or greyish- 
 green, has a somewhat slaty structure, and is opaque. It is 
 very infusible, and indeed appears quite unalterable by heat ; 
 a quality which, combined with its softness when first taken 
 from the quarry, and its hardening by exposure to the air, 
 renders it an excellent material for many objects of domestic 
 use, such as ovens, stoves, pots, &c. They are esteemed not 
 only for their indestructibility, but because they can never give 
 any bad taste or quality to the food. It is quarried at several 
 places in Piedmont ; particularly near Chiavenna and the 
 Lake of Como ; also in the Valais : it is extensively manufac- 
 tured in the Val Sesia, not far from Mount Rosa; and at 
 Zoeblitz in Saxony. The pieces of a fine even texture are 
 turned by the lathe into teapots, basins, &c. If a vessel of 
 potstone, after being used for some time, has absorbed much 
 
 I 
 
66 
 
 SERPENTINE MEERSCHAUM. 
 
 grease, it is usual to make it red hot, a process which renders 
 it as clean as new, and without injury. 
 
 Pliny speaks of this stone, and describes its application to 
 the same purposes as at present : but calls it Lapis Siphnius, 
 because at that time it was obtained from the Isle of Siphnos, 
 now Siphanto. At the convent of the Great St. Bernard 
 there is a stove of potstone. 
 
 48. Serpentine (Ophite). A compact substance, very 
 tough, breaking with an uneven fracture and waxy lustre, or 
 dull and earthy. Generally of a dark green colour intermixed 
 with black, and sometimes with red and brown : opaque, 
 except the kind called precious serpentine , which, when cut into 
 thin slabs, is semi-transparent : it is of a rich warm green 
 colour and often contains embedded garnets : this sort is 
 found at Baireuth in Austria. 
 
 Serpentine differs very much in hardness, but all specimens 
 are easily scratched by a knife, and many by calcspar. Not- 
 withstanding this, it is much employed in slabs for ornamental 
 purposes ; particularly those varieties in which, like the verde 
 antique , the dark colours are relieved by spots and veins of 
 white calcspar. Handsome serpentine is quarried at Anglesea, 
 and used under the name of Mona marble. 
 
 Marmolite is a foliated serpentine, containing less silica 
 than the preceding ; both species give off water when heated. 
 
 49. Meerschaum (Magnesite ; Ecume de Mer) is an earthy 
 opaque substance resembling white clay, but dry and harsh to 
 the touch ; partially soluble in acids, and affording much water 
 by calcination. 
 
 It is well known as a material of which pipes are made ; it 
 is extensively quarried for that purpose in Asia Minor, par- 
 ticularly at the foot of Mount Olympus, and in the Island of 
 Negropont. In some places it is used instead of soap for 
 washing linen, and is said to form a good lather when mixed 
 with water. 
 
 The adhesive slate (schiste happante) in which menilite is em- 
 bedded, is a mixture of meerschaum with argillaceous matter. 
 
DIALLAGE — SCHILLERSPAR. 
 
 67 
 
 50. Diallage. This mineral, which has not been found 
 crystallized, is embedded in serpentine, and, occasionally, 
 other rocks, in fragments which are cleavable ; there are 
 several varieties, which are composed chiefly of silica, mag* 
 nesia, and the protoxyde of iron, with only a trace of lime. 
 
 Bronzite is of a greyish brown colour, translucent and, as 
 its name implies, with submetallic lustre ; specific gravity 
 3*25. It is found in France, department of the Higher Alps. 
 
 Hypersthene* (Labrador Hornblende) ; of a dark brown 
 colour, reflecting a coppery lustre. The laminae are some- 
 times so much bent, that it has the appearance of a woody 
 structure. Specific gravity 3*3 : this mineral is much harder 
 than the preceding : its principal locality is Labrador. 
 
 Anthopyllite has generally a fibrous structure, and a pale 
 hair-brown colour ; lustre, slightly metallic : distinguished 
 from bronzite by its brittleness. 
 
 51. Schillerspar (Diallage-euphotide) . Like the pre- 
 ceding species, it occurs with a lamellar structure, but no 
 external crystallization ; embedded in serpentine, or in rocks 
 containing albite. Its colour is dark olive or greyish green ; 
 hardness about 4. It differs in composition from diallage in 
 containing 10 or 12 per cent, of water: when exposed to the 
 action of the blowpipe, it becomes magnetic, but is scarcely 
 fusible on the edges. 
 
 Smaragdite f contains 7 per cent, of the oxyde of chrome, 
 which gives it a fine clear green colour. It has a laminated 
 structure, is very translucent and brittle : fusible into a 
 blackish glass. 
 
 The rocks consisting of smaragdite intermixed with albite, 
 are cut into slabs, and when polished are very beautiful. In 
 Corsica it is abundant, and is known by the name of verde di 
 Corsica duro : it is found also in rolled masses on the borders 
 of the Lake of Geneva. 
 
 52. Nephrite (Axestone ; Jade). A compact substance, 
 
 * Huper above, and sthenos strength, from its remarkable toughness, 
 f Smaragdus the emerald, from its colour. 
 
68 
 
 AUGITE, 
 
 generally of a green colour, but sometimes grey, or reddish. 
 It breaks with an uneven but fine-grained fracture, and has a 
 feeble oily lustre. Laminse of a silvery talc are sometimes 
 dispersed through it. Hardness variable, sometimes above that 
 of quartz, and exceedingly tenacious. Specific gravity about 3. 
 
 Some of the finest specimens of dark green nephrite are the 
 war hatchets of the New Zealanders. This variety appears to 
 be the same which is found near the banks of the Oronooko, 
 but the precise locality is unknown. It is cut into ornaments 
 which are worn as amulets by the Indians, and even by the 
 Spaniards of that country. It is sometimes called Amazon- 
 stone. 
 
 Silicates of lime with magnesia, &c. 
 
 53. Augite (Pyroxene). This species maybe distinguished 
 into two kinds : the white augite, consisting essentially of the 
 bisilicates of lime and magnesia ; the black and dark green, in 
 which these bases are partly replaced by the protoxyde of iron, 
 which is isomorphous with them : the pale varieties contain 
 very little iron. The crystals of all kinds are derived from an 
 oblique rhombic prism ; obtuse angle, 92° 55'. Specific gra- 
 vity from 3*1 to 3*34 ; hardness 5 to 6. 
 
 Diopside , malacolite , alalite , mussite,* are denominations of 
 white and greenish-white augite. The crystals are often semi- 
 transparent, with bright glassy faces. Fusible No. 44. 
 by the blowpipe into a colourless, or nearly 
 
 colourless, glass. The best specimens of this 
 kind are obtained from some parts of Piedmont 
 and the Tyrol, where they form groups with 
 bright red garnets and mica. 
 
 Fassaite* or pyrgomme, is of a clear dark green colour, 
 usually in small distinct crystals, sometimes embedded in calc- 
 
 spar. 
 
 Sahlite is massive, generally of a light greyish green, trans- 
 lucent and cleavable, affording good surfaces. 
 
 * Named from the valleys of Ala and Mussa in Piedmont, and Fassa in 
 Tyrol. 
 
HORNBLENDE* 
 
 69 
 
 Coccolite* is granular augite ; the grains are usually com- 
 pressed together, and not dispersed in another substance. The 
 two latter varieties occur at Sahla, in Sweden, with pearly 
 calcspar and sometimes with scapolite, but they never have the 
 yellow-green colour of epidote. 
 
 Hedenbergite , black augite , basaltic augite , is rarely massive : 
 the crystals are often macled ; colour blackish green, black, or 
 brown : streak and powder greenish or brownish black. Fusi- 
 ble by the blowpipe into a black or dark green glass. 
 
 The crystals of this augite are abundant in 
 some kinds of lava, and especially in the ancient 
 lavas of Auvergne. It is an abundant as well 
 as a widely distributed mineral, being a compo- 
 nent of some kinds of basalt ( dolerite ) ; it is there 
 intimately mixed with albite, or with labradorite, 
 and gives the dark colour peculiar to that rock. 
 
 54. Hornblende (Amphibole). This species is subdivided, 
 in the same manner as augite : the white varieties consist of 
 silicates of lime and magnesia, with scarcely a trace of iron ; 
 the dark ones contain a large proportion of the latter base: but 
 both the light and dark-coloured hornblende contain less lime 
 than augites of the same colour. The crystals are derived 
 from an oblique rhombic prism; obtuse angle, T26° to 127°. 
 The black or blackish green variety, commonly called horn- 
 blende , is by far the most abundant. Its crystals are generally 
 short and thick, and have some resemblance to those of the 
 black augite. They are found principally in basalt and other 
 similar rocks ; but the angle of the prism (and of cleavage) is 
 much more obtuse in hornblende. It is often massive, and 
 embedded in felspar and albite ; intermixed with the former, it 
 constitutes the rock called greenstone; with the latter, a very 
 similar one called diorite : in both these we find the fragments 
 of hornblende with a crystalline structure, of all sizes, from 
 several inches in length to particles so small as to be undistin- 
 guishable to the naked eye. It is sometimes fibrous, having 
 * Coccos, a grain. 
 
 No. 45. 
 
70 
 
 TREMOLITE — ASBEST. 
 
 the appearance of black tourmaline ; but that’ 'mineral breaks 
 with a perfectly vitreous fracture, and hornblende with distinct 
 cleavage : it is particularly tough, also, and difficult to break. 
 
 Actinolite* (actinote) is of various shades of green, and crys- 
 tallizes in brilliant slender prisms, with four, six, or eight sides; 
 often acicular and radiated ; and penetrating quartz and othei 
 substances ; sometimes in masses of delicate glassy fibres, 
 which are very brittle. 
 
 Pargosite is the same substance, but generally in small sepa- 
 rate crystals embedded in limestone, at Pargas, in Finland. 
 
 Tremolite , or grammatite, occurs in white or greyish crystals, 
 of which the faces are bright and glassy ; or it forms fibrous 
 and radiated masses, sometimes with a pale green or lilac tint, 
 and generally translucent : these masses are embedded in the 
 dolomite of St.Gothard, the crystalline limestone of Sweden, &c. 
 The specific gravity of tremolite is 2*9 to 3 : of black horn- 
 blende about 3*3. In hardness they are rather inferior to 
 felspar. 
 
 Asbest , f Amianth, Byssolite. This remarkable substance is 
 a fibrous variety of hornblende or tremolite, of so soft a texture 
 that it can be spun and woven like flax : and from its incom- 
 bustible nature, the cloth made of it may be cleansed when 
 dirty, by burning it. The ancients are believed to have wrapped 
 their dead in cloth made of asbestos, previously to placing 
 them on the funeral pile, in order to preserve their ashes dis- 
 tinct from those of the wood. They used it also for the wicks 
 of their perpetual lamps : it is applied to the same purpose by 
 the Greenlanders of the present day. Charlemagne is said to 
 
 * Actin a ray of the sun. 
 
 f Asbestos unconsumed, amiantos undefiled. The singular properties 
 of this mineral, soft as flax, but perfectly incombustible, have given rise to 
 some strange ideas as to its origin. Marco Polo, who visited the East in 
 the 13th century, speaking of the mountains of Tartary, says, “ There is 
 found there a substance of the nature of the Salamander, which, being 
 woven, is incombustible.” The Chinese appear to have imagined that 
 the asbestos-cloth may have been manufactured “ of the hair of certain 
 rats that lived in the flames of certain volcanos.” 
 
YENITE. 
 
 71 
 
 have possessed a tablecloth woven of amianthus, which he used, 
 after dinner, to throw on the fire to cleanse it, for the amuse- 
 ment of his guests. In some parts of the Pyrenees, girdles are 
 made of the same substance, intermingled with silver threads, 
 which are highly prized, not only for their beauty, but as a 
 sort of charm. In Russia, attempts have been made to manu- 
 facture paper from amianth, but they were unsuccessful. The 
 ligniform or wood-like asbest , though it consists entirely of 
 delicate fibres, is so compact, as to admit of being cut and 
 polished : in this state it resembles petrified wood. The 
 colours are generally brown, inclining to green or grey. 
 
 In Mountain leather the fibres are very fine, and so interlaced 
 as to produce a texture resembling kid leather. 
 
 Mountain or rock cork is spongy and elastic ; its numerous 
 cavities enable it to float like vegetable cork. All these sub- 
 stances form little veins in serpentine rocks, and sometimes in 
 greenstone, often associated with talc. Fine specimens of the 
 wood asbestos come from Sterzing, in the Tyrol. The localities 
 of amianth are numerous ; at one time it was found so abund- 
 antly in Corsica, as to be used instead of tow for packing 
 minerals. Asbest is sometimes enclosed in rock crystal, and 
 gives it the appearance of cat’s-eye. 
 
 It must be observed, however, that some specimens of asbest 
 are found to be augite ; this is generally the case when they 
 occur in rocks of which augite is a constituent, or where it is 
 abundant : in hornblende and tremolitic rocks, on the contrary, 
 the asbest is usually of that species : but it is frequently im- 
 possible, without analysis, to know to which they should be 
 referred. 
 
 Ferruginous silicates with lime, &c. 
 
 55. Yenite (Ilvaite; Lievrite). A calcareous silicate of 
 iron, which crystallizes in right rhombic prisms variously 
 modified. Colour generally intense brown ; lustre approaching 
 to metallic. It may be fused without difficulty into a black 
 globule ; and in acids forms a jelly. Fine specimens, both 
 crystallized and massive, are obtained in the Isle of Elba, Rio 
 
72 
 
 RHODONITE — ELECTRIC CALAMINE. 
 
 la Marina, and it is found also in Norway and Siberia. There 
 are several other silicates of iron, some of them containing 
 water, as Nontronite and Hisingerite — but they are unimpor- 
 tant, and generally rare and little known. 
 
 Manganesian. 
 
 56. Rhodonite (Manganese spar; Rose Manganese) is of 
 a beautiful rose colour, inclining sometimes to violet : mostly 
 compact or fine granular; and generally translucent. It is suffi- 
 ciently hard and tenacious to strike sparks with steel. Specific 
 gravity, 3*6 to 3*9. Heated by the blowpipe, it becomes of a 
 dark brown colour, and when fused with borax forms a deep 
 rose-coloured enamel. The finest specimens are brought from 
 the mines near Ekaterinenburg, in Siberia. Being susceptible 
 of a good polish, it is sought for to cut into slabs for boxes, 
 and for inlaying. 
 
 Photizite and Allagite differ a little from this species in the 
 proportions of their constituents : the former is yellow or 
 yellowish grey ; the latter inclining to green or brown. 
 
 Zinc. 
 
 57. Electric Calamine is silica combined with zinc and a 
 small quantity of water. It received this name from be- 
 coming electric when heated ; it becomes at the same time 
 phosphorescent. It is sometimes found in very small trans- 
 parent crystals, often radiated, sometimes with a fibrous struc- 
 ture ; also in stalactitic forms, and with an earthy texture. It 
 occurs with other ores of zinc, both in Great Britain and other 
 countries, and is used for the production of both zinc and 
 brass. 
 
 Copper. 
 
 58. Chrysocolle. This is a bright green substance, which 
 does not crystallize, but often forms a coating on other ores of 
 copper. It is translucent, somewhat vitreous in its appearance, 
 and very brittle. By calcination it gives off water, and be- 
 comes black. 
 
 Dioptase is another silicate of copper, of a fine emerald 
 green colour ; in transparent crystals, extremely rare. 
 
BORAX. 
 
 73 
 
 Family II. — Borides. 
 
 Genus I. Oxyde of Boron. 
 
 This family is of little importance. Boracic acid (or Oxyde 
 of Boron) is contained in solution in the water of some lakes 
 in Tuscany; and is found deposited on their borders in the 
 form of white or yellowish pearly scales. It is particularly 
 abundant near Sasso, whence it has been called Sassoline. 
 Its taste is slightly saline and acid : it melts in the flame of a 
 candle, in consequence of the large quantity of water it 
 contains. 
 
 Genus II. Borates. 
 
 1. Borax, or Boracic acid combined with soda, is a sub- 
 stance much used in various manufactures. It is found crys- 
 tallized in modified prisms, which are white and transparent ; 
 soluble, with a sweetish alkaline taste. It was brought to 
 Europe originally from Thibet, where it was obtained in con- 
 siderable quantity from the edges and shallow parts of a salt 
 lake : at present it is manufactured chiefly from boracic acid. 
 
 2. Boracite consists of boracic acid, combined with mag- 
 
 nesia. It has been found only in small and distinct crystals, 
 embedded in gypsum, in Saxony, and at Kiel in 46 . 
 
 Holstein : these are cubes, of which the alternate ^ 
 angles only are replaced; sometimes by one, 
 sometimes by three planes ; this peculiarity dis- 
 tinguishes it from all other minerals which crys- 
 tallize in cubes, that in any degree resemble it. 
 
 Boracic acid combined with lime and silica, forms 
 
 3. Datholite, a colourless vitreous mineral, crystallizing 
 in right rhombic prisms ; but the crystals are small and rarely 
 distinct. In some of its chemical characters it resembles the 
 zeolites, but in fusing it tinges the flame green. 
 
 Botryolite is nearly the same in composition, but it does not 
 crystallize. Both minerals are found at Arendahl in Norway. 
 
 
 E 
 
7 4 
 
 DIAMOND. 
 
 Family III. — Carbonides. 
 
 Genus I. Carbon. 
 
 Carbon and its combinations afford several minerals that are 
 interesting, either on account of their utility or their beauty ; 
 among the latter we find the 
 
 1. Diamond. This gem, so highly valued, is carbon in a 
 state of perfect purity ; that element which enters so largely 
 into the composition of all animal and vegetable matter. It is 
 always found crystallized, and its forms belong to the cubic 
 series : the most common are octahedrons with the edges re- 
 placed, and dodecahedrons; and in most instances the secondary 
 faces, however brilliant, are con- 
 vex. Notwithstanding its extreme 
 hardness, far greater than that of 
 any other known substance, the 
 diamond yields readily to cleavage, 
 parallel to the planes of the regular 
 octahedron. Its specific gravity is 
 3 '48 to 3*55. It is found of many colours, rose, yellow, blue, 
 green, and brown ; bright tints, however, except yellow, are 
 rare; though it is generally transparent, unless when very 
 dark coloured ; rarely with a milky or opaline appearance. Its 
 brilliancy is very great, in consequence of its uncommonly high 
 refractive power, and its lustre is termed adamantine. 
 
 The fact of the diamond being carbon, is proved by its 
 combustion, which takes place when it is exposed to a very 
 high temperature : like charcoal, it is converted, by this opera- 
 tion, into carbonic acid. 
 
 It is still sometimes asserted that diamonds, after being 
 exposed for some time to the sun’s light, if taken into a dark 
 room, will shine, giving out the rays they have absorbed ; but 
 the account seems to have originated in an eastern tradition. 
 
 Until the beginning of the eighteenth century, diamonds 
 were obtained only from India, where they are still found in 
 several provinces, particularly that of Golconda in Hydrabad, 
 
DIAMOND. 
 
 75 
 
 and the island of Borneo: but in 1728 the existence of 
 diamonds in Brazil became known to some Portuguese co- 
 lonists, who discovered the mines at Serro do Frio. They 
 have since been found in other places, generally within ten or 
 twelve leagues of the city of Tejuco. The most extensive 
 mines are those of Mandanga on the river Jighitonhona : it is 
 said also that the Serro San Antonio and the district of Rio 
 Plata are rich in diamonds. Still more lately, in 1829, 
 diamonds were discovered on the western side of the Ural 
 Mountains, accompanied, as in Brazil, by grains of gold, and 
 sometimes of platina. 
 
 Both in India and South America the diamonds are found 
 in the beds of streams, mixed with sand and quartz pebbles 
 and grains of gold, sometimes all connected together by brown 
 ochry clay : the crystals are often so much enveloped by this 
 crust, as not to be visible till they are separated from it by 
 washing. 
 
 Diamonds were valued by the ancients, doubtless on account 
 of their hardness and scarcity ; for they were unable to cut or 
 even to polish them. The clasp of Charlemagne’s mantle, 
 which is preserved in the Museum of Paris, was adorned with 
 four uncut diamonds of octahedral form. But about the 
 middle of the fifteenth century, a young man of Bruges, ob- 
 serving the effect of rubbing two diamonds together, made the 
 experiment of cutting them by means of diamond- dust , and suc- 
 ceeded: the same method is employed at the present day. 
 Diamond cutters avail themselves also of the cleavable struc- 
 ture of the diamond to remove some parts, and thus reduce 
 them to something like the desired form. The octahedral 
 points, which cannot be removed in this manner, are reduced 
 by rubbing them against another diamond, each being fixed, by 
 means of cement, to the end of a stick. When a facet is thus 
 produced, the position of the diamond is changed, and it un- 
 dergoes the same process in another direction : and when it 
 has assumed the proper form, the facets are polished on the 
 skive ; a thin circular plate of soft iron, charged with diamond 
 
 e 2 
 
76 
 
 GRAPHITE. 
 
 powder, which is made to revolve rapidly ; the diamond being* 
 fixed by solder to a stick, and pressed moderately against it. 
 Such as are unfit for cutting are called bort : and of these, a 
 great part is broken up, reduced to powder, and sold to 
 lapidaries : splinters are sharpened to a fine point, and used as 
 drills for other hard substances, and for engraving on gems 
 and agates ; and many are set in metal, and used by glaziers 
 to cut glass : for this purpose, only the natural crystals are 
 available, and particularly such as have the edges convex. 
 
 Diamonds have also been used with advantage for the lenses 
 of microscopes, and are constantly employed by engravers, 
 instead of steel points, for ruling lines to produce flat tints. 
 
 Diamonds of a large size, that is to say, above ten or twelve 
 carats,* are rare ; though some few have been found weighing 
 upwards of a hundred. The most celebrated ones, that are at 
 oresent in the possession of different sovereigns, have already 
 been described by so many authors, that the reader is referred 
 to their works for an account of them.f 
 
 2. Graphite (Plumbago ; Blacklead ; Mine de plomb). 
 The substance called blacklead is well known to most persons ; 
 but few perhaps are aware, that when they make use of a 
 blacklead pencil they draw with a substance which is nearly 
 identical with the Diamond. It appears to be carbon, differing 
 from it, when pure, only in the state of aggregation of its 
 particles : it often contains a small quantity of earthy matter, 
 or of iron ; but as the latter amounts to only 1 or 2 per cent., 
 both are now generally considered as accidental impurities. 
 Graphite has always a metallic lustre, with sometimes a fine 
 scaly structure, and soils the fingers when handled. Specific 
 gravity, 2 to 2*45. 
 
 The best graphite is that of Cumberland, but it is found in 
 many other parts of Europe, and large blocks have lately been 
 
 * The carat is a weight used by diamond merchants, which is rather 
 less than four grains troy. 
 
 f Particularly “ Minerals and their Uses, in a Series of Letters to a 
 Lady,” by J. R. Jackson, Esq. 
 
NAPHTHA. 
 
 77 
 
 imported from Ceylon : it occurs also in Canada, and at 
 several places in the United States ; generally in detached 
 masses of various sizes, or small grains, embedded in gneiss or 
 slate rocks. 
 
 For the best pencils, it is used without any other prepara- 
 tion than that of sawing it into thin strips, which are after- 
 wards enclosed in wood, or formed into thin rods for the 
 ever-pointed pencils : but great numbers of pencils of inferior 
 quality are made of a mixture composed of blacklead dust, 
 intermixed with clay, and sometimes with lampblack, or sul- 
 puret of antimony. 
 
 Genus II. Carburet. 
 
 1. Carburetted Hydrogen. This is the gas called by 
 miners fire-damp . It is formed in abundance in coal-mines, 
 and, being highly inflammable, on the approach of a lighted 
 candle or lamp it ignites and explodes, producing serious 
 accidents, and often loss of life. 
 
 2. Naphtha (mineral oil) is a limpid fluid of a yellowish 
 colour, much lighter than water, and very inflammable ; on 
 exposure to the air, it thickens and becomes darker. There are 
 springs of this liquid in several countries ; as in Albania, and 
 at Amiano near Parma, where it is collected and employed for 
 lighting the city of Parma. On the western shores of the 
 Caspian, where the soil is light and sandy, on making a small 
 hole to the depth of a few inches, and inserting a tube, naphtha 
 may be immediately obtained : and at Baku, in the north of 
 Persia, are the remains of temples built by the ancient inha- 
 bitants, fire-worshippers, who kept it constantly burning, 
 believing it to be of sacred origin. 
 
 Petroleum (liquid bitumen) is naphtha, containing bitumen ; 
 it is nearly black, and much thicker than naphtha. It oozes 
 out of rocks in the neighbourhood of coal beds, and hardens by 
 exposure to the air, from the evaporation of the naphtha. At 
 Rangoon, in the kingdom of Ava, this substance is found in 
 great abundance : the pits, whence it is obtained, yield above 
 400,000 hogsheads annually. It is common in many other 
 
78 
 
 COAL. 
 
 countries, both of Asia and Europe, and found in several parts 
 of North America. The bricks of which Babylon was built, 
 were cemented by petroleum in place of mortar : the Egyptians 
 employed it in the process of embalming ; and to the present 
 day, the boats on the Tigris are tarred with petroleum. 
 
 Asphaltum is another variety of bitumen, which is solid and 
 hard, breaking generally with a glossy conchoidal fracture, 
 and very much resembling vegetable pitch. When pure it 
 will float on water, and in this manner is collected from the 
 Dead Sea; but it is often mixed with earthy matter, and is 
 then heavier than water. 
 
 In the island of Trinidad there is a very remarkable small 
 lake, which appears to be entirely filled with asphaltum. 
 Near the shore it is solid and hard, but at a short distance it is 
 warm and soft, and increases in temperature towards the 
 centre, where it seems to be in a boiling state ; and even 
 the surface of the solid part seems to have been cooled sud- 
 denly when in a state of ebullition. 
 
 The asphalt of Seyssel, and other parts of France and 
 Switzerland, used for some years past in paving, is of the 
 same kind.* 
 
 • 3. Coal consists chiefly of carbon, which in different kinds 
 is united with various proportions of bitumen. 
 
 Anthracite (mineral charcoal or glance coal) is the kind 
 which contains the smallest amount of hydrogen, and no bitu- 
 men ; for this reason it burns without flame or smoke, and with 
 difficulty. It is used as fuel in lime-kilns and furnaces. It is 
 hard, dry to the touch, and shining. 
 
 Common or slaty coal (houille) differs from the above in con- 
 taining bitumen : this is the substance, which, when coal has 
 been a short time on the fire, we see oozing and boiling out of 
 the cracks in the manner of pitch. Coal is a brittle mineral, 
 and most varieties have a tendency to break into somewhat 
 
 * Naphtha is found to consist wholly of carbon and hydrogen : petro- 
 leum and asphaltum appear to contain oxygen likewise, and traces of azote. 
 Naphtha is purified from the bitumen it generally contains, by distillation. 
 
LIGNITE — JET — COLOGNE EARTH. 
 
 79 
 
 rectangular fragments. Its specific gravity is not above 1*5; 
 and the hardness, which is less than that of anthracite, is variable. 
 
 Cannel coal is very compact, with an even texture; and 
 breaking with a large conchoidal fracture and scarcely any 
 lustre. It burns readily, and with so bright a flame, that thin 
 pieces have been used as candles. It is sometimes turned or 
 cut into boxes, inkstands, and other objects, but it does not 
 receive a very brilliant polish. 
 
 This is an excellent sort of coal for burning, because it con- 
 tains more hydrogen than any other : this gas, combined with 
 a portion of carbon, is obtained from coal by distillation, and is 
 the gas employed for lighting streets and houses : the bitumen, 
 also, which is volatile at a certain heat, is obtained by the same 
 process, and is used under the name of coal tar . 
 
 These, and other varieties of coal, form extensive beds, in- 
 terstratified with other rocks, principally sandstone and slaty 
 clay, or shale : the coal strata are generally much thinner than 
 the intervening beds, and often appear only at considerable 
 intervals, after several repetitions of them. 
 
 Lignite , bituminized wood , or brown coaly differs from black 
 coal in having a woody structure, and in containing a different 
 sort of bitumen, which burns with a peculiar odour : it appears 
 to be coal of imperfect or more recent formation than the other 
 kind. There is a considerable deposit of it near Bovey, in 
 Devonshire, and it is common in many other countries. 
 
 Jet is a very compact lignite, which, when broken, has a 
 brilliant lustre : the original woody structure may, notwith- 
 standing, often be perceived ; and it is even found sometimes 
 in the form of branches and stems of trees. Large quan- 
 tities of jet are found in the Department of Aude, in the South 
 of France; and several, hundred persons formerly gained a 
 living in that part, by turning and carving it for ornaments ; 
 but the consumption is now much diminished. 
 
 Cologne earth , which is used for painting, is a decomposing 
 variety of brown coal, and in the vicinity of Cologne it is 
 damped and pressed into moulds and used as fuel. 
 
80 
 
 AMBER MELLITE — CARBONIC ACID. 
 
 4. Amber (Succin). It occurs in irregular roundish pieces 
 from the size of a nut to masses weighing several pounds, 
 which are generally embedded in lignite or in the sandy strata 
 belonging to the same formation. The colour of transparent 
 varieties is yellow or brown ; the opaque specimens are often 
 white. Specific gravity 1 to 1*18; hardness 2 to 2*5. 
 
 Amber is sometimes found containing insects, which seems 
 to confirm the supposition that it is, originally, a vegetable 
 resin, hardened, and, perhaps otherwise altered by time and 
 situation. Amber may be distinguished from substances which 
 are sold under that name, by its greater hardness and tenacity, 
 and its becoming more strongly electric by friction. It burns 
 with an agreeable odour. 
 
 Retinasphalte is a mineral resin of a light brown colour, 
 nearly opaque, sometimes earthy, which occurs in lignite : it is 
 soluble in alcohol. 
 
 Highgate resin or fossil copal , schiereritey hatchetine and dyso- 
 dyle , are all minerals of a resinous nature, generally occurring 
 with lignite, or near it. 
 
 Genus III. Mellate. 
 
 Mellite, which has also been called honeystone, from its 
 colour, occurs in square octahedrons, resembling bits of yellow 
 resin, embedded in lignite, in Thuringia. It consists of alu- 
 mina and water, united to mellitic acid, which contains, by 
 weight, about equal quantities of carbon and oxygen. Burns 
 to a white ash. 
 
 Genus IV. Oxyde of Carbon. 
 
 Carbonic Acid (Fixed Air) exists in some mineral 
 waters, giving them the sparkling pungency of artificial soda 
 water. It destroys life and combustion, and being much 
 heavier than the air of the atmosphere it is dangerous to 
 descend into caverns where it is naturally generated : the 
 Grotto del Cane, near Naples, is celebrated for the effects 
 produced by the fixed air, which fills it to a level with the 
 entrance. Its compounds are comprised in the next genus. 
 
NATRON — CALCSPAR. 
 
 81 
 
 Genus V. Carbonate. 
 
 The minerals comprised in this genus are characterised by 
 their solubility in acids, at the same time disengaging carbonic 
 acid by effervescence; some, however, require heat to effect 
 their solution. 
 
 1. Natron (Carbonate of Soda) occurs in nature as a 
 powder or incrustation, which, if pure, is white ; otherwise, 
 yellowish or grey. It is perfectly soluble, and its alkaline 
 taste is generally known : crystals obtained artificially are 
 transparent at first, but effloresce by exposure to the air, and 
 are soon covered with a white pulverulent coating. 
 
 Natron is abundant in some of the lakes of Egypt, Arabia, 
 and India ; and in Hungary, during the summer months, the 
 ground often becomes white with this salt, as if covered with 
 snow. 
 
 2. Trona, which contains less water and more carbonic 
 acid, does not effloresce. Between Tripoli and Fezzan in 
 Africa, it forms a thin bed of a fibrous structure, from which 
 hundreds of tons are extracted annually. It is found likewise 
 in Columbia. 
 
 3. Carbonate of Lime. Few minerals present so great a 
 variety in their appearance, and none afford so many crystalli- 
 zations. 
 
 Calcspar , which we have mentioned more than once, is car- 
 bonate of lime in its purest state : its specific gravity is 2*6 to 
 2*73 ; hardness 3. Its crystals are derived from a rhombohe- 
 dron, No. 49, which is easily obtained by cleavage, the planes 
 meeting at an inclination of 105° 5'. 
 
 The annexed figures. No. 3, p. 7, and Nos. 5, 8, 10, p. 8, 
 
 No. 49. No. 50. No. 51. 
 
82 
 
 SATINSPAR — LIMESTONE. 
 
 occur more frequently than most others ; No. 4 and 7, p. 8, 
 also, are not uncommon. 
 
 Calcspar is generally transparent or translucent ; the faces 
 of the crystals, sometimes very brilliant ; but it is remarkable 
 that the bases of the hexagonal prisms are alway opaque. It is 
 sometimes perfectly colourless, often of a topaz or honey-yellow, 
 greyish, or reddish. When pure it consists of 56*3 of lime, 
 and 43*7 of carbonic acid: but it frequently contains some 
 carbonate of iron or magnesia, or is coloured by oxyde of iron 
 and clay. 
 
 Exposed to the blowpipe, carbonate of lime does not swell nor 
 fall to powder, but becomes white and caustic ; it is then quick 
 lime : some varieties are phosphorescent when heated, and shine 
 with a pale yellow light. Crystals of calcspar are rarely found 
 embedded in other rocks, as is so commonly the case with gar- 
 nets, tourmalines, and many other minerals; but they form 
 groups in the clefts of calcareous rocks, and the cavities of 
 metalliferous veins. The copper mines of Derbyshire and 
 Leicestershire, and the lead mines of Durham, afford beautiful 
 specimens ; and very fine crystallizations occur in the silver 
 mines of the Hartz Forest, particularly of the hexagonal prism. 
 
 Satinspar consists of fine parallel fibres, either straight or 
 waved, and has a silky lustre; it fills small veins in limestone 
 rocks, the fibres lying across the vein. 
 
 Limestone is a general name applied to all massive varieties 
 of carbonate of lime that form beds of great extent, or moun- 
 tains. Some kinds are granular, with a highly crystalline 
 structure, such as the marbles of Paros and Carrara, which are 
 employed in sculpture : they are likewise called sacharoide , 
 from their resemblance to loaf sugar. Other marbles are com- 
 pact, as the yellow marble of Sienna, several richly coloured 
 marbles of Spain (obtained chiefly from the Pyrenees), and a 
 beautiful black marble with clear white spots, which is quarried 
 in the South of France (Arriege ; Aude ; Basses Pyrenees). 
 
 There are many other sorts, containing an immense number 
 of petrifactions. Some of the grey Derbyshire marble consists 
 
ROESTONE CHALK — STALACTITES. 
 
 83 
 
 I imost entirely of portions of encrinites (called there, screw- 
 tones) ; a similar kind is found in the neighbourhood of Mons, 
 nd extensively used in Paris for tables and other furniture, 
 uder the name of petit granit . Others are full of the remains 
 of shells, both bivalves and univalves, some of which retain 
 tie pearly lustre and brilliant colours of recent shells. The 
 limestone of the South of Devon, (Plymouth marble,) which is 
 much used there for chimney pieces, &c., abounds in fossilized 
 madrepores of a grey colour, prettily veined with red and white. 
 
 Stinkstone is limestone containing a large proportion of bitu- 
 men, which when rubbed or scratched by any hard substance, 
 or slightly heated, gives out a strong fetid odour : it may be 
 observed in some of the black and grey marble of Derbyshire. 
 
 Oolite or roestone , so named from its resemblance to the roe 
 of a fish, forms large beds, extending through a great part of 
 England. The Bath and Portland building stone are good 
 examples of it. 
 
 Feast one or pisolite differs from it only in the larger size of 
 the grains. 
 
 Chalk is carbonate of lime of an earthy texture. It forms 
 the cliffs along the south-east coast of England, which acquired 
 for our island the name of Albion. The lower stratum is much 
 more compact than the upper chalk, and less white. 
 
 Rockmilk resembles chalk, but is much more tender : it is 
 found in the clefts of mountains, where it is deposited by water 
 containing calcareous particles. 
 
 Stalactites* are sometimes transparent and have the crystal- 
 line structure of calcspar, sometimes they consist of parallel 
 layers or bands of different degrees of translucidity or shades of 
 colour ; this sort is often employed for vases and slabs, under 
 the names of alabaster and onyx marble . 
 
 Calcareous tufa . In Derbyshire are several springs, called 
 there petrifying springs , which quickly incrust any object im- 
 mersed in them, by depositing on it the lime they hold in solu- 
 tion : this incrustation is tufa or tuff. But the most remarkable 
 * See p. 15. 
 
84 
 
 ARRAGONITE — DOLOMITE. 
 
 water of this kind is that of a stream at St. Allyre, near Cler- 
 mont, in Auvergne, which, having been allowed to run for a 
 length of time in the same channel, formed by degrees an 
 embankment 240 feet long, 12 feet wide, and 16 feet high 
 at the extremity ; and near it runs another stream, whose cal- 
 careous waters have raised an arch so broad and solid, thet 
 carriages pass over it in safety. 
 
 Limestone rocks are intersected by veins affording the ores 
 of lead, zinc, and copper, and afford specimens of these inter- 
 mixed with fluorspar, calcspar, and quartz. 
 
 The limestone rocks also contain the most extensive and inte- 
 resting caverns ; they are generally adorned with stalactites 
 which assume the form of obelisks, gothic architecture, groves, 
 wreaths, and draperies ; sometimes of dazzling whiteness, some- 
 times sparkling with innumerable tufts of crystals. 
 
 4. Arragonite (Hard carbonate of lime) appears to be the 
 same substance as calcspar, but differs in its greater hardness, 
 which is nearly that of fluorspar; and in its crystallizations, 
 which originate from a rhombic prism. It never forms large 
 masses like the rocks and strata of limestone, but its crystals 
 are found in several situations : very fine ones occur in a red 
 clay near Molina in Arragon, and in Valencia : and a beautiful 
 variety, in the form of a delicate coralline and snow white, is 
 brought from some of the mines of Styria and Bohemia : it was 
 formerly thought to be a carbonate of iron, and called flos-ferri. 
 
 Several analyses of arragonite indicate a very small quantity 
 of carbonate of strontia and water as constituents : but the 
 proportion being variable and not exceeding 4*7 per cent., it is 
 doubted whether these ought to be regarded as essential to its 
 composition, or accidental. 
 
 5. Dolomite (Miemite ; Bitterspar; Magnesian limestone) . 
 This is a combination of the carbonates of lime and magnesia, 
 generally in about equal parts, sometimes with a small portion 
 of carbonate of iron, which, however, does not affect the crys- 
 tallization. At first sight, the crystals of dolomite might be 
 mistaken for those of calcspar, but they present no other variety 
 
CARBONATES OF MAGNESIA AND IRON. 
 
 85 
 
 than primary rhombohedrons, sometimes large, transparent, 
 and brilliant ; or the same solid, with a single modification on 
 the lateral angles. It affords brilliant cleavages, is a little 
 harder than calcspar, and dissolves with scarcely any percep- 
 tible effervescence. 
 
 Pearlspar or brownspar is a crystallized variety, common in 
 England, particularly among the lead and copper ores ; it is 
 distinguished by its lustre, and the curvature of the faces : it is 
 sometimes of a golden-yellow colour, but more often brown : 
 translucent or nearly opaque. 
 
 Gurhofian is white and compact, with the texture of porce- 
 lain. 
 
 Granular dolomite has very much the appearance of white 
 marble ; but is more easily crumbled. A great part of Mount 
 St. Gothard, and the mountains of the Tyrol, are of this sub- 
 stance, which produces the finest crystallized specimens. 
 
 Magnesian limestone is finely granular and generally of a 
 yellowish grey colour. It forms extensive beds in the North 
 of England, and has been selected as a building-stone in the 
 construction of the New Houses of Parliament. The lime 
 obtained by burning this limestone, is said to make excellent 
 mortar. 
 
 6. Carbonate of Magnesia (Giobertite; Magnesite). — 
 This is a scarce substance ; found occasionally in serpentine, 
 either in fibrous plates, or small rhombohedral crystals. Hard- 
 ness 3 to 4. 
 
 Nemalite is the same, containing water ; sometimes in grey 
 silky fibres, sometimes white and earthy, resembling the mag- 
 nesia of the shops. Both occur at Hoboken, in New Jersey. 
 
 7. Carbonate of Iron (Ironspar; Spathic iron; Siderose). 
 This mineral also crystallizes in the same system, and presents 
 some of the same forms as calcspar. Beautiful groups of the 
 flat rhomboid. No. 5, p. 8, rounded on the edges so as to 
 have the form of a lens, are obtained in Piedmont, and at 
 Baigorry, in the Pyrenees : hexagonal prisms from St. Agnes, 
 in Cornwall, and other varieties from Cumberland, usually as- 
 
86 
 
 CARBONATES OF MANGANESE AND ZINC. 
 
 sociated with quartz. They are generally of a yellowish grey, 
 or a rust colour ; rarely white. Sometimes it is massive, with 
 a crystalline structure, filling veins, and exactly resembling 
 calcspar in appearance : it may be distinguished, however, from 
 that mineral by greater hardness = 4, higher specific gravity 
 = 3 to 3*8, and by its darkening and becoming magnetic when 
 heated by the blowpipe. . 
 
 Clay iron ore , a mineral extensively used in the English iron 
 foundries, is carbonate of iron rendered impure by an inter- 
 mixture of clay and silica, oxyde of iron, and other carbonates ; 
 it is earthy or compact, generally grey or brown, and occurs in 
 flattened nodules in the coal districts. They very generally 
 contain impressions of fossilized ferns and other plants. 
 
 8. Carbonate of Manganese (Diallagite) . Generally of 
 a pale rose colour ; cleavable parallel to a rhombohedron rather 
 less obtuse than that of calcspar. Specific gravity 3*2 to 3*6. 
 It is a rare mineral, found occasionally in Saxony and Transyl- 
 vania. Distinguished from Rhodonite by inferior hardness. 
 
 9. Carbonate of Zinc (Calamine, Smithsonite) is abun- 
 dant in many of the localities of lead ores, particularly in Eng- 
 land and Carinthia. It is massive, stalactitic, or incrusting, not 
 unfrequently crystalline, and is another example of the preva- 
 lence of the rhombohedral system in the carbonates ; but crystals 
 are small and not frequent, resembling No. 3, p. 7, and No. 8, 
 
 p. 8.* 
 
 Calamine dissolves with very perceptible effervescence ; but is 
 distinguished from calcspar by volatilizing before the blowpipe. 
 It is smelted with other ores of zinc. 
 
 * For the convenience of reference a list is annexed of the obtuse angle 
 of cleavage in the rhombohedral carbonates. 
 
 Diallagite 
 
 t— > 
 
 o 
 
 CO 
 
 o 
 
 Calcspar . 
 
 o 
 
 O' 
 
 o 
 
 cn 
 
 Dolomite 
 
 o 
 
 CTi 
 
 o 
 
 t— < 
 
 Carbonate of iron 
 
 107° 
 
 Carbonate of magnesia 
 
 107° 25' 
 
 Carbonate of zinc . 
 
 107° 40' 
 
CARBONATES OF BARYTA, STRONTIA, AND LEAD. 87 
 
 10. Witherite (Carbonate of Baryta). This mineral is 
 abundant in many of the English lead mines, particularly in 
 those of Alstone Moor, Shropshire, and Anglesark in Lanca- 
 shire; it is rarely crystallized, but occurs in large masses 
 resembling alum. When powdered and thrown on hot coals, 
 it emits a phosphorescent light; but it is distinguished from 
 most other carbonates and earthy minerals, chiefly by its high 
 specific gravity = 4*29, which, however, has occasioned its 
 being mistaken for a lead ore. Fusible, without addition, to a 
 glassy globule. 
 
 The salts of baryta used in chemical analyses, are prepared 
 from witherite, and in the North of England it is used as a 
 poison for rats. 
 
 Barytocalcite is a carbonate of baryta and lime, found at 
 Alstone Moor. 
 
 1 1 . Strontianite (Carbonate of Strontia). A mineral that 
 was first discovered among lead ores at Strontia in Argyle- 
 shire, and is still found in some few other localities. It is rarely 
 crystallized, but occurs fibrous and coarse granular, almost 
 constantly of a pale yellow-green colour, and translucent. 
 Specific gravity 3*6. It may be fused by a strong heat, and 
 gives a red colour to the flame, a property which has caused it 
 to be used in pyrotechny. 
 
 12. Carbonate of Lead (White Lead Ore; Native ceruse ; 
 Lead spar). This is the same substance as the white lead of 
 commerce, which is prepared artificially. It is abundant in 
 some lead mines, filling large veins or intermixed with other 
 ores, either compact, earthy, or crystalline. Its crystals are 
 derived from a right rhombic prism,* differing very little from 
 that of witherite, and are often grouped so as to form a cross 
 or a star. It is the only mineral which equals the diamond in 
 brilliancy ; its lustre, when pure and transparent, being ada- 
 
 * Angle of the rhombic prisms which are the primary forms of 
 Witherite . . . . 118° 57' 
 
 Strontianite . . . . 117° 32' 
 
 Carbonate of lead . . . 117° 
 
88 
 
 AZURE CbPPER ORE. 
 
 mantine. It is brittle ; and the specific gravity as high as 6*5 
 to 6*7. When fused by the blowpipe on charcoal, a bead of 
 lead is obtained ; or if dissolved in nitric 
 acid, upon immersing a piece of zinc (the 
 surface being quite clean) metallic lead 
 will quickly be precipitated on it in bril- 
 liant laminae. Either of these operations 
 will distinguish it from witherite. Some 
 of the finest crystallizations are brought from the lead mines 
 of Lanarkshire. When massive it has sometimes a crystalline 
 structure, splitting readily into large flakes with a brilliant sur- 
 face. An earthy variety, resembling chalk in its appearance, 
 is common in the lead mines of Durham 
 and Derbyshire. But it is a mineral met 
 with not only in lead mines : it is frequently 
 found with copper pyrites and blende : and 
 in Cornwall, with antimony, and other 
 minerals peculiar to that district. In these 
 situations it often forms columnar masses 
 or acicular crystals, with a silky lustre. 
 
 The sulpho-carbonate of lead, which is this substance com- 
 bined with about one third of its weight of sulphate of lead, 
 resembles it in brilliancy and weight, but when dissolved in 
 nitric acid, it leaves a residue which is sulphate of lead. 
 
 Carbonate of Copper. 
 
 This term comprises three species, differing in the propor- 
 tions of their constituents : but they are all soluble in acids, 
 and their solutions will precipitate metallic copper on the blade 
 of a knife, or any piece of clean iron immersed in them. 
 
 13. Azure Copper Ore is a beautiful mineral of a dark 
 blue colour, inclining to purple, and, when pure, semi-transpa- 
 rent and vitreous ; when powdered, a bright azure. It is 
 generally crystallized, in short oblique prisms somewhat modi- 
 fied, which are often grouped into globular and reniform 
 masses ; when more slender, in tufts. 
 
 No. 52. 
 
M AL AC H ITE — WATER. 
 
 89 
 
 The finest specimens are obtained in Hungary, and at 
 Chessy, near Lyons, where it is abundant ; it is generally 
 converted into the sulphate of copper , an application which is 
 found to be more profitable than smelting it for copper, although 
 it contains above 50 per cent, of the metal. 
 
 14. Malachite is another beautiful substance : it is rarely 
 crystallized, but occurs in botryoidal and reniform masses, 
 from the size of a nut to a foot or more in diameter, with a 
 smooth surface and a finely fibrous structure. Its colour is a 
 bright pure green ; and when broken it exhibits concentric 
 bands of various shades, following the curves of the surface. 
 It is little harder than calcspar, but is much employed for 
 objects of ornament, since, notwithstanding its softness, it 
 receives a fine polish ; and when cut, the concentric rings of 
 dark and light green have a very pleasing effect. Hitherto, the 
 large and fine blocks of malachite employed for these purposes 
 have been obtained from Siberia : but it appears probable that 
 the Burra Burra mines in South Australia may soon rival that 
 long celebrated locality ; as they have already produced com- 
 pact masses of great beauty, and crystallized specimens both of 
 this and the blue carbonate. These ores differ in composition, 
 the blue carbonate containing less copper and water, and more 
 carbonic acid, than malachite. 
 
 15. A dark brown mineral, without lustre, and sectile, has 
 been found in India, which is said to be anhydrous carbonate of 
 copper . 
 
 Family IV. — Hydrogenides. 
 
 Genus I. Hydrogen. 
 
 Pure hydrogen is rarely met with in nature ; but mixed with 
 sulphuretted hydrogen, it is often disengaged from fissures in 
 the earth, during volcanic eruptions and earthquakes. 
 
 Genus II. Water. 
 
 A great deal might be said about this most useful substance, 
 which exists in so many forms, and under so many different 
 
90 
 
 WATER — AZOTE. 
 
 circumstances. When, perfectly pure, it consists (by weight) 
 of the following matters in combination : 
 
 Oxygen 88*9 
 
 Hydrogen 11*1 
 
 But all water, whether pure or saline, contains some atmo- 
 spheric air, without which it would be unfit for the support of 
 either animal or vegetable life. The clearest springs generally 
 contain, also, particles of one or more salts in solution. When 
 the saline matters are in such quantity that the springs derive 
 from them medicinal properties, they are called mineral waters : 
 such are the springs of Cheltenham, Leamington, and others. 
 Sea water derives its bitter taste from the salts of magnesia 
 that it contains. 
 
 Warm springs are common in several countries ; and some 
 have a very high temperature. The celebrated water of Bar- 
 rages in the Pyrenees, which is impregnated with sulphureous 
 vapours, varies from 99° to 117° (Fahr.), and the spring of 
 Bagneres de Luchon, of the same kind, raises the thermometer, 
 sometimes, above 140°. 
 
 The Geysers, or boiling fountains of Iceland, at a depth of 
 some yards, must be far hotter than boiling water at the surface 
 of the earth, and hold even silica in solution. 
 
 Although water is liquid at a moderate temperature, when 
 solidified by cold it crystallizes and assumes the form of hexa- 
 gonal prisms, and a variety of stellar figures, always having six 
 rays or branches at equal angles : these crystallizations are 
 often perceptible in flakes of snow. 
 
 Family V. — Nitrides. 
 
 Genus I. Nitrogen or Azote. < 
 
 This gas is contained in the water of many springs : it is 
 said, that from one of the warm springs of Bath upwards 
 of 200 cubic feet are disengaged daily. 
 
 Azote combined with oxygen forms nitric acid : its combina- 
 tions constitute 
 
SALTPETRE — SULPHUR. 
 
 91 
 
 Genus II. Nitrates. 
 
 These salts are all soluble in water, and, when thrown on 
 live coal, cause vivid combustion. 
 
 1. Saltpetre (Nitre; Nitrate of potash). On the surface 
 of the soil and on the sides of caverns, chiefly in calcareous 
 countries, and on the walls of old buildings and cellars, this 
 salt is often met with in the form of a thin crust, or tufts of 
 minute crystals. In India, Spain, and Egypt, large quantities 
 aie collected from the ground during the hot weather succeed- 
 ing the periodical rains. In Kentucky, and some other of the 
 United States, it is obtained from the earth that forms the 
 floor of caverns. One of its principal uses is in the fabrication 
 of gunpowder, and it is employed in medicine, and in the pre- 
 paration of nitric acid. 
 
 2. Nitrate of Soda. This salt is obtained in large quan- 
 tity in Peru, near the Bay of Yquique, from a bed from two to 
 three feet thick, where it is mixed with glauber salt, sand, and 
 the remains of recent shells ; the whole appearing as if it had 
 been covered by the sea at no very distant period. Burns on 
 coal with a strong yellow light. 
 
 3. Nitrate of Lime, and 4. Nitrate of Magnesia, are 
 found dissolved in the water of some springs ; the latter cha- 
 racterised by its bitter taste : they are also formed on old walls 
 along with saltpetre. 
 
 Family VI. — Sulphurides. 
 
 This family contains a great number of substances that are 
 highly important and useful in the arts of life, particularly most 
 of the ores whence we obtain copper, silver, lead, zinc, and 
 antimony; and they are not less interesting to the minera- 
 logist from the beauty and variety of their crystallizations and 
 colours. 
 
 Genus I. Sulphur. 
 
 Native Sulphur, when crystallized, is a beautiful mineral : 
 the crystals are transparent, of a bright yellow slightly inclining 
 
92 
 
 SULPHURETTED HYDROGEN. 
 
 to green ; or, when they contain selenium, of a rich orange 
 tint. They are acute octahedrons, sometimes with the sum- 
 mits, sometimes the edges replaced, the base being a rhomb. 
 
 The finest specimens are obtained from the mines near 
 Cadiz ; and from the Val di Noto and Val di Mazzara, in 
 Sicily, where groups of brilliant crystals are prettily contrasted 
 with those of celestine, equally brilliant and of a pure white. 
 In both these localities the sulphur is embedded along with 
 gypsum, in the strata which furnish rock salt. But by far the 
 greater part of the sulphur which is employed in different ma- 
 nufactures and chemical preparations, is derived from those 
 great depositories called Solfatara , which exist in the imme- 
 diate neighbourhood of modern volcanos, such as those of Puz- 
 zuoli, near Naples, in Sicily, and Guadaloupe. It is said that 
 in 1820 Sicily produced 70,000 tons of sulphur, of which 
 40,000 were exported to Great Britain alone. Sulphur is col- 
 lected also from the crater of Vulcano (Lipari) ; and other 
 active volcanos furnish it abundantly. In these deposits the 
 sulphur is massive, in crusts and stalactitic forms, and often 
 opaque. 
 
 The uses of sulphur in the manufacture of gunpowder and 
 sulphuric acid are well known : combined with mercury , it 
 produces vermilion; and it is employed in bleaching and in 
 medicine. 
 
 Genus II. Sulphurets. 
 
 1. Sulphuretted Hydrogen. Those who have tasted the 
 Harrowgate water are acquainted with one distinguishing 
 character of this gas, — its smell, resembling that of rotten eggs. 
 It is dissolved in the water of many other springs both in 
 Europe (Pyrenees) and America (Virginia). It is owing to 
 this gas floating in the atmosphere of all large towns, that 
 silver and copper so soon become tarnished when left exposed 
 to the air ; it unites with the metal, superficially, and forms 
 sulphurets of silver and copper. 
 
 2. Cinnabar. This is a sulphuret of mercury, and occurs 
 in various states : sometimes in crystals which are perfectly 
 
CINNABAR. 
 
 93 
 
 transparent, brilliant, and of a fine deep carmine colour : some- 
 times massive, with a granular structure, the colour inclining 
 to steel grey, and the lustre slightly metallic ; and, occa- 
 sionally, as a fine powder of a rich scarlet colour (native 
 vermilion), which is contained in the cavities of massive 
 cinnabar. There is also an impure variety, with a slaty struc- 
 ture, of a dark liver-red or blackish colour, which contains, 
 besides earthy matter, carbon, and sometimes bitumen ( hepatic 
 ore). 
 
 The crystals are six-sided prisms, generally modified on 
 alternate edges ; but they are usually very small and complex. 
 The specific gravity of cinnabar, when pure, is 8, which is 
 higher than that of any ore w T hich resembles it. But if a 
 specimen should not be recognised by its external characters, 
 it may be ascertained by the blowpipe : the sulphur will burn 
 away with a pale blue flame and sulphureous smell ; and the 
 whole of the mercury will be volatilized by the heat ; and if a 
 piece of clean copper be held over the vapour of the cinnabar, 
 it will be coated with mercury. 
 
 From this ore the greater part of the mercury of commerce 
 is obtained by a -process of distillation. 
 
 There are in Europe several extensive deposits of cinnabar ; 
 particularly at Almaden, in Spain (Province of La Mancha) ; 
 at Idria, in Carniola; and at Potzberg, in the Duchy of Deux 
 Ponts, on the Rhine. Those of Idria, discovered in 1497, are 
 very extensive and productive, though the ore, which is prin- 
 cipally hepatic cinnabar, is less rich than that of Almaden. 
 Pliny records that from the latter place the Greeks imported 
 red cinnabar 700 years before the Christian era ; and that in 
 his time the Romans received thence, annually, 700,000 lbs. 
 weight. The principal vein under exploration is from 14 to 
 16 yards in thickness, and appears rather to increase than 
 diminish in width, as it descends into the earth. 
 
 In the Idrian mines, a great conflagration took place in 
 1803, and the volatilized mercury occasioned dreadful diseases 
 among 900 persons in the vicinity. The health of the work- 
 
94 
 
 SILVER GLANCE. 
 
 men employed in the quicksilver mines suffers very much 
 from the poisonous vapours constantly floating in the air they 
 breathe. 
 
 Sulphurets of Silver. 
 
 3. Silver Glance (Vitreous Silver; Argyrose). This 
 ore, when pure, consists of 8 6*5 parts of silver, and 13*5 of 
 sulphur, and furnishes the principal part of the silver of com- 
 merce, being the most abundant of its ores, and, if we except 
 native silver , the richest. It is of a dark steel-grey colour, 
 with metallic lustre, and is found both massive and crystallized 
 in forms belonging to the cubic system (figs. 2, 3, 8, 9), but 
 without any trace of cleavage ; and the surface of the crystals 
 is often bluish-black, or iridescent. Its specific gravity is 6*9 
 to 7‘2; higher than that of copper glance, the mineral which 
 it most resembles : it is soft and sectile, so that small chips 
 may be cut off without crumbling. 
 
 By exposing it to the blowpipe, a bead of silver is obtained, 
 without the addition of any flux, the sulphur gradually burning 
 away : it is soluble in dilute nitric acid, and if a piece of copper 
 be dipped into the solution, metallic silver will be deposited on 
 its surface. This test applies equally to all .silver ores when 
 dissolved in acid. 
 
 In the rich silver mines of Saxony and Bohemia, situated in 
 the mountains of the Erzgebirge, this ore forms considerable 
 veins : but those worked in the mines of Mexico and Potosi 
 greatly surpass them in size. The crystals adhere to the 
 sides of cavities, and are accompanied sometimes by calcspar, 
 sometimes by quartz, and often by copper pyrites. 
 
 4. Brittle Silver Glance (Black Sulphuret of Silver) is 
 a sulphuret of silver containing antimony, which is of a darker 
 colour than the preceding, and when powdered appears quite 
 black. The crystals, which are rare, are hexagonal prisms, 
 sometimes terminated by pyramids, or modified by planes on 
 the terminal edges. 
 
 The blowpipe reduces it to a bead of silver; the sulphur 
 burning away and the antimony being volatilized in white 
 
RED SILVER ORES. 
 
 95 
 
 fumes. It occurs principally in the silver mines of Schemnitz 
 in Hungary, and Freyberg in Saxony, where it is wrought and 
 smelted. 
 
 5. Red Silver Ore (Ruby silver; Rubinblende) is of two 
 kinds — the dark red silver ore is a sulphuret of silver and 
 antimony, the light red silver ore in place of antimony con- 
 tains arsenic : externally they differ only in depth of tint, 
 both occurring in crystallized masses of a beautiful ruby colour, 
 sometimes so intense as to appear black ; the crystals resemble 
 some of the forms which belong to calcspar, and are derived 
 from a similar rhombohedron. The powder of the antimonial 
 ore is dark red ; that of the arsenical, scarlet. When exposed 
 to the blowpipe, both kinds afford a bead of silver : the anti- 
 mony of the one evaporating in white fumes, and the arsenic 
 of the other producing the characteristic smell of garlic. They 
 contain from 59 to 64 per cent, of silver : the brittle silver 
 ore is still richer. 
 
 They are all found in several localities of silver glance, 
 though comparatively in small quantity in the European mines : 
 but in some parts of America, particularly Mexico, dark red 
 silver is the principal ore, and the mines of Somberete and 
 Cozala, where that species chiefly is raised, have produced 
 immense quantities of metal. 
 
 Myargyrite is an antimonial sulphuret, which affords but 
 36*5 per cent, of silver : externally it is black and semi- 
 metallic, but when powdered appears to be very deep red. 
 
 Polybasite , which is rich in silver, contains about 9 per cent, 
 of copper and iron : colour, dark steel-grey. 
 
 The presence of copper may be detected by dissolving the 
 globule, obtained by fusion, in nitric acid : the copper will be 
 quickly deposited on a knife blade dipped into the solution. 
 
 Stromeyerine , a sulphuret of silver and copper, has been 
 found at Schlangenberg in Siberia, in small compact masses of 
 an iron-grey colour and metallic lustre. These substances 
 occur in but few of the great depositories of silver ores, and in 
 very small quantity. 
 
96 
 
 COPPER GLANCE. 
 
 Sulpburets of Copper. 
 
 There are several combinations of sulphur with copper, 
 some of which, the copper glance, copper pyrites, and varie- 
 gated copper, are valuable ores. 
 
 6. Copper Glance (Vitreous Copper Ore). This is the 
 grey copper ore of the Cornish miners ; it has a dark steel- 
 grey colour, and when freshly broken a perfectly metallic 
 lustre ; but the exterior is often black and dull. Its crystals 
 belong to the rhombohedral system, and are generally short 
 hexagonal prisms, with the terminal edges replaced or ter- 
 minated by pyramids : and, sometimes, double pyramids 
 occur, without any intervening prism. It is more often, how- 
 ever, found in masses without any regular form, or filling 
 small veins. When not crystallized it might easily be mis- 
 taken for the sulphuret of silver, but the fracture has less 
 brilliancy, and the copper ore melts easily before the blowpipe, 
 but is not so quickly reduced without soda. The specific 
 gravity, also, does not exceed 5*8. 
 
 This is the richest of all the sulphurets of copper, affording 
 75 per cent, of metal, and being in general very free from any 
 other. It has been met with in some of the Cornish copper 
 mines, but only in small quantity ; but in the Oural mountains 
 it is an object of extensive exploitation : it is said to occur 
 there in nodules of various sizes, disseminated in veins of clay 
 and gravel. 
 
 7. Variegated Copper Ore (Phillipsite). This was long 
 considered to be the same substance as copper pyrites, of 
 which the surface was tarnished ; but it differs from it in con- 
 taining less iron and sulphur, affording about 60 per cent, of 
 copper, while copper pyrites does not yield more than 33 or 34. 
 The poorness of the latter, however, is compensated by its 
 greater abundance. Both the crystallized and mammelated 
 varieties usually exhibit brilliant colours, in which purple tints 
 are the most conspicuous : these, however, are superficial, and 
 on breaking it the colour appears to be rather browner than 
 that of metallic copper. Crystals are rare : they are generally 
 
COPPER PYRITES. 
 
 97 
 
 cubes with the angles replaced (PI. fig. 2) ; sometimes it 
 forms a thin coating on crystals of copper glance, and it is 
 often disseminated amongst quartz and other minerals. It is 
 softer than copper pyrites, and the colour much redder : and 
 it is less easily fusible than copper glance. Specific gravity 
 about 5. 
 
 8 . Copper Pyrites (Yellow Copper Ore) is the most 
 abundant of the English copper ores. Its colour is that of 
 brass, and its lustre perfectly metallic and shining, particularly 
 when fresh broken. It is easily scratched by a knife ; differing 
 in this character from iron pyrites , which is much harder. 
 Groups of small crystals, which are tetrahedrons variously 
 modified, or octahedrons, differing little from the regular one, 
 are often sprinkled over other substances, as quartz, calcspar, 
 fluorspar, galena, and blende ; but they are very seldom distinct 
 or perfect. 
 
 Copper pyrites, when pure, consists of sulphur 35*87, 
 copper 34*40, and iron 30*47. Both this and the variegated 
 ore, when fused by the blowpipe, afford a globule which is 
 attractable by the magnet. 
 
 Copper pyrites forms veins in granite, slate, and other 
 rocks, sometimes filling them entirely, sometimes distributed 
 in irregular masses varying in size, and occasionally weighing 
 some hundreds of pounds. The Derbyshire mines, those of 
 Freyberg in Saxony, and St. Marie aux Mines in Alsace, have 
 produced the most beautiful specimens of this ore. 
 
 9. Grey Copper Ore (Fahlore, or Fahlerz). The com 
 
 position of this ore varies exceedingly in different localities ; 
 but it still presents nearly the same appearance ; a light grey 
 metallic substance, either massive, or crystallized in the form 
 of the regular tetrahedron, which is gene- n 0# 54 . 
 
 rally modified by planes on the edges or 
 angles. It consists principally of sulphuret 
 of copper, antimony, and iron, with arsenic, 
 zinc, or silver, and sometimes with all 
 these metals : the proportion of silver 
 
 F 
 
98 
 
 BELLMETAL ORE. 
 
 \ 
 
 amounts in some instances to 1 7 per cent. ; the ore is then 
 worked for the sake of the silver as well as of the copper : this 
 is the case in the mines of Chili. Good crystals are sometimes 
 obtained in the Cornish mines. 
 
 10. Bellmetal Ore (Tin pyrites). A rare mineral which 
 has been found, hitherto, only in Cornwall : it is metallic, of a 
 yellowish-grey colour, inclining to red, and consists of sulphur 
 30*5, copper 30, tin 26*5, and iron 12. Does not crystallize; 
 specific gravity 4*3 to 4*78. 
 
 11. Tennantite is a sulphuret of copper and arsenic, which 
 is also peculiar to a few localities in Cornwall. It occurs in 
 small black brilliant crystals, which are rhomboidal dodecahe- 
 drons, sometimes with the angles truncated. 
 
 Sulphuret of iron. 
 
 Of this there are three species ; two of which, common and 
 white iron pyrites , differ in crystallization, but, like calcspar and 
 arragonite, consist of the same elements and in the same pro- 
 portions; namely, sulphur 52*70 and iron 47*30: the third 
 species, magnetic pyrites, is composed of sulphur 40*15 and 
 iron 59*85. Their specific gravity varies from 4*6 to 5. 
 
 12. Common Pyrites (Martial pyrites; Mundic of the 
 Miners) is a yellow metallic substance, crystallizing in cubes, 
 octahedrons, and more particularly in 
 forms presenting faces of the pentagonal 
 dodecahedron (PI. figs. 13, 14, 15, 16). 
 
 The planes of the cube are very often 
 streaked in directions corresponding to 
 these faces. Independent of its crystal- 
 lizations, which are generally perfect and 
 often on a large scale, it may be distinguished from copper 
 pyrites by its paler colour, more conchoidal fracture, and 
 greater hardness, scratching glass and striking fire with steel. 
 This latter property of pyrites was known to the ancients, who 
 gave it the name it still bears, which means fire-stone . For 
 the same reason, it was used in the early times of fire-arms, 
 instead of the gun-flints by which it was afterwards replaced. 
 
 No. 55. 
 
IRON PYRITES. 
 
 99 
 
 The ancient Peruvians are thought to have used it for mir- 
 rors, small polished plates of it having been found in some of 
 their tombs ; hence in that country it is still sometimes called, 
 piedro de los Ineas. Formerly, when steel buttons were in 
 fashion, pyrites also was cut into such ornaments, and worn 
 under the name of marcasite. 
 
 At the present time, though it is applied to none of these pur- 
 poses, it is very useful, being employed in the production of 
 sulphuric acid, alum, and sulphate of iron, or copperas. 
 
 Iron pyrites is one of the most abundant ores in nature, and 
 more universally distributed perhaps than any other mineral, 
 being found in every kind of rock that we are acquainted with. 
 In some localities, it contains particles and scales of gold : at 
 Beresof in Siberia, and Macugnaga in Piedmont, the gold 
 occurring in this manner is a principal object of research. 
 
 13. White Iron Pyrites, so called from its very pale 
 colour, occurs in groups of thin tabular crystals derived from a 
 rhombic prism, which present a number of very sharp or acute 
 edges: from its peculiar forms it has been called cockscomb 
 pyrites and spear pyrites . 
 
 The radiated nodules so common in the chalk cliffs, are 
 of this kind : their exterior is often of a brown colour, and 
 without any metallic lustre ; this is the result of decomposition, 
 by which it is converted into hydrous oxyde of iron ; entire 
 crystals have sometimes undergone this change, and are called 
 hepatic pyrites. Both kinds are found in coal, and their decom- 
 position occasions the spontaneous combustion that sometimes 
 takes place in coal mines. 
 
 Ignorant persons often persuade themselves that the small 
 veins and scales of pyrites in coal, may be gold ; but gold is 
 malleable and sectile, qualities which do not belong to pyrites. 
 
 14. Magnetic Pyrites is of a darker colour, inclining to 
 that of bronze, and is much softer than the other species; 
 when crystallized, it assumes the form of the hexagonal prism. 
 It is not a plentiful substance, but has been found in Cornwall, 
 Derbyshire, and several other countries. 
 
 f 2 
 
100 
 
 ARSENICAL PYRITES — GALENA. 
 
 15. Arsenical Pyrites (Mispikel) is nearly as white as 
 silver, and hard enough to give sparks with steel, at the same 
 time emitting a strong odour of arsenic, of which it contains 
 above 40 per cent. It abounds in the tin veins of Cornwall 
 and Bohemia, mostly in crystals, which are rhombic prisms 
 modified on the angles ; and sometimes embedded in rocks of 
 granite and micaschist ; but rarely in the veins which afford 
 silver and lead. It is sometimes radiated. 
 
 16. Alabandine (Manganblende ; Sulphuret of Manga- 
 nese). In the gold mines of Transylvania, this ore, which is 
 black and metallic, occurs, penetrating or embedded in the 
 rose-coloured manganese. Infusible. 
 
 17. Molybdenite. This ore, which is a pure sulphuret of 
 molybdenum, occurs in small masses which strongly resemble 
 graphite ; but with care they may be separated into thin 
 laminae, which are flexible, but not elastic. Sometimes, but 
 rarely, it is crystallized in hexagonal plates. 
 
 It has been found in the granite of Cumberland and the tin 
 veins of Cornwall, as well as the Alps, Norway, &c. It may 
 be distinguished from graphite by dissolving in nitric acid. It 
 was thought, in the first instance, to be a native metal, and 
 received the name molybdenum from its resemblance to lead. 
 
 18. Galena (Sulphuret of Lead). This may, in general, 
 be easily recognised by its crystallizations, and its very perfect 
 cleavages, parallel to the faces of a cube, as well as by its pure 
 lead-grey colour. 
 
 Its most common forms are figs. 3, 4, PI. ; also perfect 
 cubes and octahedrons, and, less often, cubes having the edges 
 replaced, figs. 8, 12. The surface of the crystals is often dull, 
 but that of the fracture always brilliant; and it is so brittle 
 that cleavages may be obtained by a very slight blow. The 
 same crystalline structure prevails where the galena is massive, 
 sometimes resembling that of statuary marble ; more rarely it 
 is fine granular, or compact with scarcely any lustre. Its spe- 
 cific gravity is 7*5 to 7’ 7. It is easily fused, giving off sul- 
 phureous fumes, and affording a globule of lead. 
 
BOURNONITE — BLENDE. 
 
 101 
 
 Some galena is combined with sulphuret of silver. When 
 this is in sufficient quantity to render it worth the expense of 
 separating the silver, it is called argentiferous galena. This is 
 the case in Cornwall and Devon, where several per cent, of 
 silver are obtained from the lead. 
 
 In order to know whether galena contains any silver, dissolve 
 a little in nitric acid, and dip into the solution a piece of cop- 
 per : the silver, if there be any, will be deposited as a white 
 metallic film on the copper. 
 
 There is a singular kind of galena found in Derbyshire, called 
 slickensides : it forms a thin coating on the sides of some of the 
 veins, having a polished though not always a flat surface, as if 
 produced by friction. It is said that if this film be scratched 
 it explodes violently ; for which reason, the miners, when they 
 discover a mass of slickensides, carefully avoid touching it, till 
 they are at some distance, when one of them strikes it with a 
 nail fastened to a long pole, and quickly runs out of the way. 
 
 19. Bournonite (Endellion) is a sulphuret of lead, copper, 
 and antimony, the former amounting to 40 per cent. It is 
 found in some mines in Cornwall, Saxony, and the Hartz, 
 in very small crystals, nearly black, which are rectangular 
 prisms much modified. 
 
 20. Blende (Sulphuret of Zinc; Black Jack of Miners). 
 This, when pure, is of a yellow colour, slightly tinged with 
 green; but it is much oftener dark reddish brown, or garnet 
 red, and contains some portion of sulphuret of iron. It crys- 
 tallizes in the form of the rhomboidal dodecahedron, and very 
 perfect cleavages may be obtained parallel to the faces both of 
 this solid and of the octahedron. The yellow blende is trans- 
 parent, the darker varieties more or less translucent. The 
 crystals, both externally and when fractured, have considerable 
 brilliancy, but very little metallic lustre : in specimens that are 
 not cleavable, the fracture is often waxy. Blende contains 
 from 50 to 60 per cent, of zinc, the remainder being sulphur 
 andiron; its specific gravity is 4*16. Some varieties become 
 phosphorescent by slight friction. 
 
102 
 
 NICKEL BISMUTH ANTIMONY. 
 
 Radiated Blende is of a dark brown colour ; it is said to con- 
 tain 2 or 3 per cent, of cadmium , and occurs in nodules. 
 
 Blende is found principally in the same localities as Galena, 
 and often intermixed in the same vein ; but its crystals are 
 associated also with the ore of copper, and sometimes of tin. 
 It is used in the fabrication of zinc and brass, though it was 
 formerly thrown aside as worthless. White vitriol also (sul- 
 phate of zinc) may be prepared from it by decomposition. 
 
 21. Sulphuret of Nickel (Hair pyrites). A rare sub- 
 stance, which occurs in some veins of the Bohemian and 
 Saxon silver mines, and also in Cornwall, in little tufts of 
 crystals as fine as hairs, which are of a greenish colour and 
 metallic. It is soluble in nitric acid, and the solution becomes 
 violet on the addition of ammonia. 
 
 22. Nickel Glance (Grey Nickel) is a combination of 
 nickel with sulphur and arsenic, which is found in small masses, 
 compact or lamellar, at Helsingland in Sweden. 
 
 23. Sulphuret of Bismuth (Bismuth glance). This ore 
 also occurs in tufts of slender crystals both in Cornwall and 
 some other of the localities of the nickel pyrites ; but it may be 
 distinguished by its greater fusibility, melting even in the flame 
 of a candle ; and when fused by the blowpipe on charcoal, it 
 leaves on it a yellow deposit, which is the oxyde of bismuth. 
 It contains 81 per cent, of bismuth. 
 
 Argentiferous bismuth ore has been found with fluor, at 
 Baden, in a similar form. 
 
 24. Needle Ore is a sulphuret of bismuth, lead, and copper, 
 of a lead-grey colour and metallic lustre. It occurs pene- 
 trating quartz and other earthy matters, in the mines of 
 Ekaterinenburg in Siberia, and likewise in the silver mines of 
 Bohemia, Saxony, &c. 
 
 25. Sulphuret of Antimony (Grey Antimony). From 
 this ore all the antimony of commerce is obtained. Its lustre 
 is shining and perfectly metallic, and it occurs either massive 
 or crystallized in rhombic or six-sided prisms, generally ter- 
 minated by four planes. It is seldom that more than one 
 
ZINKENITE. 
 
 103 
 
 termination is visible, the crystals being aggregated in diver- 
 gent groups : sometimes they are several inches in length : 
 very often acicular, and even capillary, intersecting each other 
 in all directions : one variety, (plumose antimony,) consisting 
 of delicate fibres interlaced, resembles felt. The surface of the 
 crystals is sometimes tarnished with brilliant prismatic colours ; 
 otherwise its colour is lead-grey. It is soft and very tender, 
 yielding to the pressure of the nail ; specific gravity 4*3 to 4*6. 
 Cleavable in one direction with ease, and affording thin laminae, 
 which are flexible. 
 
 This mineral is fusible in the flame of a candle, and when 
 exposed to the blowpipe it is entirely volatilized in white 
 fumes. It contains from 73 to 75 per cent, of antimony, the 
 remainder being sulphur. It is distributed through most 
 countries of Europe, but there are few in which it is very 
 abundant : the most extensive mines are those of Hungary 
 and the central part of France : it is met with also in Cornwall, 
 and has been brought from Borneo. 
 
 Antimony is applied to many purposes : one most impor- 
 tant use is in the composition of type metal y for which it is 
 alloyed with lead ; and in forming pewter and Britannia Metal , 
 it is combined with tin. Several medicines also are prepara- 
 tions of antimony. 
 
 26. Haidingerite (Berthierite). A sulphuret of antimony 
 containing 15 per cent, of iron and 52 of antimony, which 
 occurs in considerable quantity at Chazelle, in Auvergne, in 
 masses with a confused lamellar structure. It resembles grey 
 antimony ore in its appearance, but by exposure to the blow- 
 pipe affords a globule which is attractable by the magnet. 
 
 It has been worked as an ore of antimony, but abandoned in 
 consequence of the difficulty experienced in separating the iron. 
 
 27 and 28. Zinkenite and Jamesonite are Sulphurets of 
 antimony with lead. Both have a steel-grey colour ; the former, 
 from Wolfsberg, in the Hartz, crystallized in hexagonal prisms, 
 or fibrous ; the latter occurring in small rhombic prisms, or 
 fibrous, in Cornwall and Hungary. 
 
104 
 
 COBALT GLANCE. 
 
 Geocronite , Plagionite , and Boulangerite are all sulphurets of 
 antimony and lead, differing only in their proportions. 
 
 Kobellite is a radiated ore consisting of the sulphurets of 
 antimony, lead, and bismuth, from Hvena, in Sweden. 
 
 29. Sulphueet of Cobalt (Cobalt Pyrites) is a metallic 
 mineral of a light grey colour, breaking with a fine granular 
 fracture, which has been found massive, and, more rarely, 
 crystallized in octahedrons, at Ryddarhytten, in Sweden. Com- 
 posed of 43 per cent, of cobalt, 41 of sulphur, and a small 
 quantity of copper and iron. 
 
 30. Cobalt Glance (Cohaltine ; Silver White Cobalt). 
 This ore occurs in small distinct crystals, which are white with a 
 faint tinge of red, a perfectly metallic lustre, and considerable 
 brilliancy. It crystallizes in the same forms as iron pyrites, 
 particulaidy figs. 13, 14, 15. Cobalt glance, however, may be 
 distinguished by its colour and greater specific gravity, = 
 6*29, and being more brittle. It consists of cobalt 33, sulphur 
 20, arsenic 43, iron 2. 
 
 On heating it by the blowpipe, it gives off arsenical fumes, 
 which is not the case with the above-named ore : but both 
 substances communicate an intense blue to borax or any other 
 flux ; this result is characteristic of all the ores of cobalt. It 
 may further be distinguished from iron pyrites and arsenical 
 pyrites, by giving a rose-coloured solution in nitric acid. 
 
 Cobalt glance is found in greater quantity in Norway and 
 Sweden than in any other country, and is there intermixed 
 with copper pyrites. From this ore is prepared a great part 
 of the smalt and other cobalt blues used in the potteries and 
 for other kinds of painting. It is first converted into a sili- 
 cated oxyde, called ZafFre, by calcining the ore, in order to 
 volatilize both the sulphur and arsenic, and then heating it with 
 about twice its weight of flint reduced to a fine powder. In 
 this state it is brought to England, where smalt is prepared from 
 it, by remelting the ZafFre with a proper quantity of glass, or 
 glass and potash : this compound, while in a state of fusion, is 
 poured into cold water, which causes it to break into small 
 
REALGAR — ORPIMENT. 
 
 105 
 
 angular pieces, like gravel ; this is ground, washed, and sepa- 
 rated into smalt of different degrees of fineness. Besides its 
 use in painting on porcelain and with oil, a great deal of this 
 colour is consumed in giving a blue tinge to paper, muslin, 
 calico, &c. 
 
 Sulphuret of arsenic. 
 
 This is of two kinds : Realgar, containing 69 per cent, of 
 arsenic, and Orpiment, which contains only 62 per cent. 
 
 31. Realgar (Red orpiment) occurs in small granular 
 masses and crystals of a fine crimson red colour, which are 
 transparent or translucent, perfectly vitreous and without me- 
 tallic lustre. The crystals are derived from an oblique rhombic 
 prism and are often complex. It is so soft as to yield to the 
 nail, and is brittle. Specific gravity 3’ 3 to 3*6. 
 
 Realgar is wholly volatilized by the blowpipe, a circumstance 
 in which it differs from the red silver ores ; while the arsenical 
 fumes produced by the operation distinguish it from cinnabar : 
 it differs from cinnabar likewise in colour ; for when pulverized 
 it appears orange-red, while cinnabar is of pure crimson. 
 
 Realgar is found most abundantly in the silver mines of 
 Hungaria, Bohemia, and the Hartz ; sometimes with native 
 arsenic : and it is met with in smaller quantity in the craters of 
 volcanoes and the solfataras in their vicinity, where it is often 
 intermixed with the following species. 
 
 32. Orpiment. This is very different in appearance from 
 realgar : it is very rarely crystallized, but generally in lamellar 
 masses of a brilliant lemon or golden colour : the laminae are 
 easily separated, and have somewhat of the pearly lustre of 
 talc. The texture is sometimes compact or earthy. Its hard- 
 ness, specific gravity, and chemical characters are nearly the 
 same as those of realgar. The finest specimens of orpiment 
 come from Persia, and require no other preparation than grind- 
 ing, to be used as a pigment ; it is also prepared in Saxony, 
 artificially ; but this has not so fine a colour as the native orpi- 
 ment. Realgar also is sometimes used in painting, but unfor- 
 tunately it is not a permanent colour. 
 
 p 5 
 
106 
 
 SULPHURIC ACID — ALUM. 
 
 Genus III. Oxydes of Sulphur. 
 
 % 
 
 1. Sulphuric Acid (Oil of Vitriol). 
 
 2. Sulphurous Acid. 
 
 These are both produced by the combustion of sulphur in 
 volcanic regions. They escape from the earth in the form of 
 vapour, which is quickly absorbed by the pools and streams in 
 the vicinity, and thus produce the acidulous waters which are 
 sometimes found in subterranean cavities, such as the Grotto 
 of Santa Fiora, in Tuscany, and the caverns of the Isle of 
 Milo. 
 
 Sulphurous acid is recognised by its suffocating odour, re- 
 sembling burning sulphur : the same effect will be perceived 
 from sulphuric acid by immersing charcoal in it and heating it. 
 
 The composition of sulphurous acid is sulphur 50*14, oxygen 
 49*86; of sulphuric acid, sulphur 40*14, and oxygen 59*86. 
 
 Genus IV. Sulphates. 
 
 These salts, with very few exceptions, are transparent, crys- 
 talline substances, and the greater part of them are soluble in 
 water. 
 
 1. Alum. The alum of commerce is a well-known sub- 
 stance which may be obtained crystallized in octahedrons, either 
 simple or with the angles, and less often the edges, replaced : 
 but in nature crystallized alum is rare. It occurs most fre- 
 quently as an efflorescence, or in silky fibrous masses. At 
 Whitby, in Yorkshire, and near Paisley, the slate rocks are 
 quarried for the purpose of obtaining the alum from them ; 
 this is done likewise in France, Germany, and other countries. 
 
 The common alum of the shops consists of sulphate of alu- 
 mina, sulphate of potash, and water ; but native alum contains, 
 more frequently, iron instead of potash, and has somewhat of 
 the inky taste of the pure sulphate of iron : this kind is some- 
 times called feather alum or plumose alum , from its form : it is 
 generally of a yellowish colour. There is also feather alum , 
 which contains no other salt than the sulphate of alumina. 
 
ALUMSTONE CELESTINE. 
 
 107 
 
 Soda alum has been observed in the Isle of Milo and in 
 South America. 
 
 Magnesia alum likewise occurs in the latter country, in con- 
 siderable masses, fibrous and silky. 
 
 Ammonia alum is found in Bohemia. 
 
 2. Alumstone (Aluminite; Alumite). This mineral differs 
 a good deal from alum, being insoluble in water, and nearly as 
 hard as felspar. It exists in large masses in Hungary, at 
 Tolfa (near Rome), and in some other localities, generally com- 
 pact, and with groups of small crystals in the cavities. These 
 are obtuse rhombohedrons, transparent, or nearly so ; and 
 colourless, greyish, or reddish. 
 
 It may be dissolved in sulphuric acid : some varieties contain 
 a good deal of silica; and that in Hungary is so hard as to be 
 used for millstones. But its chief use is in the production of 
 alum, which is obtained by calcining, and then exposing it to 
 the air, moistening it frequently with water. Alumstone con- 
 tains less acid than alum. 
 
 Websterite , a white, earthy, insoluble substance, is another 
 sulphate of alumina, which has been found at Newhaven in 
 Sussex, and Halle in Saxony. Distinguished from chalk by 
 not effervescing with acid. 
 
 3. Epsom Salt (Epsomite ; Sulphate of Magnesia ; Sel 
 d’Angleterre ; Sel de Sedlitz). Few persons are unacquainted 
 with the strong bitter taste of this salt, which imparts the 
 same quality to sea water. It is most abundant in the water 
 of some springs, and received two of its names from one long 
 celebrated at Epsom in Surrey, and another at Sedlitz in 
 Bohemia. 
 
 It occurs also, as an efflorescence, on some voluminous 
 schists of Savoy, and in the earth of numerous caves in the 
 Western States of North America. In the famous mammoth 
 cave of Kentucky, it adheres to the roof in loose masses as 
 white as snow. 
 
 4. Celestine (Strontian Spar) is the sulphate of Strontia. 
 It is generally crystallized or lamellar, rarely granular or com- 
 
108 
 
 HEAVYSPAR. 
 
 pact. The primary form is a right rhombic prism, obtuse 
 angle 104° 30'; but the larger faces of most No. 56. 
 crystals are secondary. It is transparent 
 or translucent ; sometimes colourless, but 
 more frequently a very pale blue, whence it 
 received the name of celestine ; and occasion- 
 ally flesh red. In its appearance it resembles some of the 
 zeolites, but may be distinguished by inferior hardness, and 
 higher specific gravity = 3*9 or 4, and by tinging the flame 
 red when fused by the blowpipe. Composition, sulphuric acid 
 43*64, strontia 56*36. 
 
 The finest crystallized specimens are brought from Sicily, 
 where it occurs in brilliant divergent groups, with sulphur : it 
 is not common in Great Britain, but nodules are found in 
 cavities in basalt and amygdaloidal rocks, as at Calton Hill, 
 near Edinburgh ; and in red clay near Bristol ; most of these 
 are lamellar, but some, fibrous or compact. 
 
 5. Heavyspar (Barytine ; Sulphate of baryta). This is a 
 more abundant mineral than the preced- No. 57. 
 
 ing : the crystals are most commonly ~ 
 
 tabular, presenting numerous modifica- 
 tions, and often of a very large size : they ^ 
 are derived from a prism differing very little from that of 
 celestine. It is either colourless or, from an intermixture of 
 ochry clay, brownish yellow or red ; sometimes also grey, and 
 even black. Fibrous varieties are often dark brown and 
 opaque ; when earthy it is white and opaque, resembling chalk. 
 The specific gravity of heavy spar is 4*7 ; hardness generally 
 above that of calcspar. 
 
 If sulphate of baryta, after being calcined, be exposed to 
 the sun’s rays, and then taken into a dark room, it emits a 
 reddish phosphorescent light ; this property was first observed 
 in some radiated groups of crystals from Bologna, whence that 
 variety received the name of Bologna spar : and the calcined 
 substance, powdered and made into small blocks with gum 
 water, was sold under the name of Bologna phosphorus. 
 
GYPSUM. 
 
 109 
 
 Fine crystallized specimens are obtained from the Cumber- 
 land lead mines, and the mines of Saxony and the Hartz ; also 
 from the fuller’s earth pits in Surrey. 
 
 Hepatite is a variety found in the silver mines of Konigsberg, 
 which, when rubbed or heated, emits a foetid smell. 
 
 Cawk is a name given by the Derbyshire miners to the mas- 
 sive, white, earthy kind. 
 
 Heavy spar is used to adulterate the white lead used in paint- 
 ing; and for the preparation of barytic salts for chemical 
 experiments. 
 
 Sulphate of Lime. 
 
 Of this there are two species : the one containing water ; the 
 other, anhydrous. 
 
 6. Gypsum (Selenite; Plasterstone ; Alabaster). This spe- 
 cies presents considerable variety in its appearance, but its 
 essential characters are generally the same. Its crystalliza- 
 tions are derived from a right rhomboidal prism : specific gra^ 
 vity 2*32 : hardness not exceeding 2, and most varieties yield 
 to the pressure of the nail : before the blowpipe, the most 
 transparent crystals immediately become opaque, exfoliate, and 
 are easily crumbled : and all varieties after being calcined, 
 when reduced to powder and mixed with water, harden in 
 drying into a solid mass. 
 
 Selenite* is crystallized gypsum ; the 
 crystals are generally tabular with be- 
 velled edges ; sometimes macled, forming 
 what is called the arrowhead crystal : these 
 are often very large and of a deep brown- 
 ish yellow; otherwise, selenite is gene- 
 rally colourless, transparent, and of a 
 pearly lustre, somewhat resembling stil- 
 bite at first sight : but they are easily 
 distinguished by the great difference of 
 their hardness. 
 
 Selenite may be cleaved with great 
 
 * Selene , Gr., the name of the moon. 
 
 No. 58. 
 
110 
 
 ALABASTER. 
 
 ease, parallel to the broader faces of the crystals, and affords 
 thin plates as transparent as glass : the Romans are said to 
 have covered their greenhouses with laminae of selenite, before 
 the art of glass-making was understood ; and imported it for this 
 purpose from the Isle of Cyprus, Spain, and even Africa. 
 Fine groups of transparent crystals are brought from the 
 valley of Bex, in Switzerland. 
 
 Alabaster. We have already spoken of a carbonate of lime 
 which is sometimes so named ; * but the term is now more 
 generally applied to the granular variety of gypsum. 
 
 The ancients gave the name alabastron originally to small 
 vessels of white stone and peculiar form, that were manufac- 
 tured at the town of Alabastron, in Egypt ; but afterwards the 
 term was applied to others of a similar form, or that were 
 applied to a similar purpose, such as holding ointments or 
 perfumes. f 
 
 The modern alabaster is the substance so extensively used 
 for carving small statues, groups of figures and animals ; and 
 boxes and vases, which are turned in a lathe : for these pur- 
 poses it is admirably adapted by its brilliant whiteness, translu- 
 cency, and softness. The best, in point of whiteness and 
 evenness of texture, is quarried near Volterra, in Tuscany. 
 Granular gypsum forms considerable beds in several countries, 
 often associated with beds of rock salt, as in Cheshire ; and is 
 frequently tinged and veined with red or grey. This sort is 
 extensively quarried at Chellaston, near Nottingham, and is 
 burnt for plaster of Paris. The gypsum of Montmartre, near 
 Paris, contains 7 or 8 per cent, of carbonate of lime, and is 
 used generally for plaster in the construction of buildings, 
 which is said to be superior to any other : the masses of crys- 
 talline gypsum which are found embedded in it, are prepared 
 as fine plaster for modellers. 
 
 * See p. 83. 
 
 f In the Gospel of St. Luke, chap. vii. v. 37, we find mention of this : 
 
 “ And, behold, a woman of the city brought an alabaster box of 
 
 ointment.” 
 
GYPSUM — GL AUBE RITE. 
 
 Ill 
 
 Fibrous gypsum is sometimes called satin spar ; but it differs 
 from the carbonate of line so named, not only in much greater 
 softness ; it is more translucent, and the slender columns of 
 which it consists are generally very straight. 
 
 The analyses of gypsum show it to contain, when pure, sul- 
 phuric acid 46, lime 33, water 21. 
 
 7. Anhydrous Gypsum (Muriacite ; Vulpinite; Bardi- 
 glione; Cubespar; Anhydrite). This species is much harder 
 than the preceding, scratching calcspar with ease. The gra- 
 nular kind, which is nearly compact, has much the appear- 
 ance of marble, but is more translucent, and is cut into slabs 
 for the same purposes, under the names of Marmo di Bar- 
 diglio and Vulpinite, from the names of the places where it is 
 quarried. 
 
 Muriacite is a name given to the crystallized varieties, be- 
 cause they w^ere sometimes found to contain traces of salt 
 (muriate of soda). The crystals are rectangular prisms, gene- 
 rally modified by several planes on the edges, and yield readily 
 to cleavage. Specific gravity 2*5 to 2*9. 
 
 8. Glauberite. Small crystals of this substance are disse- 
 minated in the ro^k salt and saliferous clay of Villa Rubia in 
 Toledo : they are very oblique prisms, rather flat, with sharp 
 edges. Glauberite consists of 51 per cent, of glauber salt, and 
 49 of sulphate of lime, and is partly soluble, the sulphate of 
 lime forming a sediment. 
 
 Polyhallite* so named from the numerous salts it was found 
 to contain, is of a brick-red colour, and coarsely fibrous, with a 
 bitter taste : it consists of the sulphates of lime, potash, and 
 magnesia, and occurs at Ischel in Austria. 
 
 9. Glauber salt (Sulphate of Soda). This is found as an 
 efflorescence in some parts of Austria and Tyrol, and around 
 some lakes in Siberia, in the water of which it is dissolved. It 
 has a bitter taste, producing at the same time a sensation of 
 coolness in the mouth. It consists of sulphate of soda 79*8 
 and water 20*2. 
 
 * Polus many, and halos salt. 
 
112 SULPHATES OF POTASH, IRON, AND COPPER. 
 
 Thenardite is an anhydrous sulphate of soda, obtained from 
 Espartines, near Madrid. 
 
 10. Sal Polycrest (Sulphate of Potash). A soluble salt 
 of rare occurrence, which sometimes forms a thin crust on lava ; 
 taste, bitter and saline. 
 
 11. Mascagnine (Sulphate of Ammonia) is characterised 
 by a pungent, bitter taste. It occurs in the form of a mealy 
 coating, generally of a yellow colour, on the recent lavas of 
 Etna and Vesuvius. When dissolved, the smell of ammonia is 
 perceptible. 
 
 12. Sulphate of Iron (Green Copperas; Green Vitriol ; 
 Melanterite) . This salt, which is of a sea-green colour, occurs 
 in most localittes where iron pyrites is abundant, particularly 
 the white pyrites ; and is often dissolved in subterranean pools 
 and streams of water. When crystallized, it takes the form of 
 oblique rhombic prisms. 
 
 It may generally be recognised by its inky taste, and by 
 producing a black colour if a drop of tincture of nut-galls be 
 added to a solution of it, or even a drop of strong tea ; or, by 
 adding a drop of prussiate of potash, a bright blue will be 
 obtained, which is prussian blue. It contains 45 per cent, of 
 water. 
 
 Coquimbite is another sulphate of iron, which is found in 
 great abundance in South America : near Copiapo, in Chili, it 
 occurs in beds and veins ; and in Bolivia it forms part of a hill. 
 It is colourless, brown, yellow, red, or blue, and has a granular 
 or crystalline structure. 
 
 There are some other sulphates of iron, differing somewhat 
 in their composition from these, but all soluble, and affording 
 the same results with the tests above mentioned. 
 
 13. Sulphate of Copper (Cyanose; Blue vitriol). Like 
 the other soluble metallic salts, this is rarely found crystallized ; 
 but is abundant in some localities, dissolved in water. The 
 Parys copper mine in Anglesea, was discovered in consequence 
 of the water being so strongly impregnated with this salt. 
 Both here and at Wicklow, the copper is obtained by immers- 
 
SULPHATES OF ZINC, COBALT, LEAD, AND URANIUM. 113 
 
 ing bars or any thin pieces of iron in the liquid : after some 
 months, when taken up, they appear to be converted into 
 copper ; the iron being in great part dissolved, and replaced by 
 a deposition of metallic copper. When crystallized artificially 
 it has a fine blue colour, is semi-transparent, vitreous, and very 
 brittle. 
 
 Brochantite is a sulphate of copper, of a bluish-green colour, 
 insoluble in water, which has been found in Siberia. 
 
 14. Sulphate of Zinc (White vitriol; Rockbutter). A 
 white soluble salt which is produced by the decomposition of 
 blende, and principally in those parts of mines which have been 
 abandoned. Its taste is nauseous and styptic. When dissolved 
 in water, if a small quantity of potash be added, a white gela- 
 tinous precipitate takes place. It is a substance much used in 
 dying and in medicine, but is prepared artificially. 
 
 15. Sulphate of Cobalt (Cobalt vitriol ; Red vitriol) . A 
 soluble salt, distinguished by its red colour. It arises from 
 natural decomposition of the sulphurets of cobalt, and is some- 
 times found to be dissolved in the water in mines where it 
 occurs : this may be detected by adding any alkali to the solu- 
 tion, when the liquid will become blue. 
 
 16. Sulphate of Lead (Anglesite). The crystals of this 
 mineral are generally rectangular octahedrons, variously modi- 
 fied, and cleavable parallel to the faces of a prism, very nearly 
 the same as that of celestine. In its specific gravity, which is 
 6*2 to 6*3, and in its general appearance, it resembles the car- 
 bonate of lead, but is rather softer and less brilliant, and may 
 always be distinguished from it by not effervescing with any 
 acid. 
 
 Sulphate of lead was first discovered in Anglesea, on cellular 
 quartz ; the best specimens are now obtained from Leadhills in 
 Scotland, Baden, and Siberia. 
 
 Cupreous sulphate of lead of a light blue colour has been 
 found in small quantity at Leadhills : it is coloured by the 
 copper it contains. 
 
 17. Sulphate of Uranium. At Joachimsthal, in Bohemia, 
 
114 
 
 CHLORIDES ROCK SALT. 
 
 an earthy yellow substance has been observed, soluble in acids, 
 and giving off water by calcination, which is the sulphate of 
 uranium. 
 
 In the same locality, a green sulphate occurs, which contains 
 copper as well as uranium, and is soluble in water. 
 
 Family VI. — Chlorides. 
 
 Genus I. Chlorurets. 
 
 1. Muriatic or Hydrochloric Acid is a compound of 
 chlorine with hydrogen. It is often disengaged by volcanoes 
 during eruptions, and particularly by Vesuvius, where it is pro- 
 duced in such abundance that, uniting with aqueous vapour, 
 and becoming condensed, it forms pools and rivulets of liquid 
 acid. It has a strong and pungent odour. 
 
 2. Rock Salt (Common Salt; erroneously , Muriate of 
 Soda). This important substance is very abundant in nature. 
 It has a perfectly crystalline structure, and may be easily sepa- 
 rated by cleavage into cubes. It occurs also in groups of 
 cubic crystals, which are seldom modified ; it is rarely fibrous. 
 Transparent salt is generally colourless ; but it sometimes has 
 a tinge of blue, violet, or rose colour. When stained by the 
 intermixture of the clay which often lies above it, it has a dirty 
 red colour. It consists of chlorine and sodium. 
 
 Extensive beds of salt exist in many countries, particularly 
 Poland and Hungary. The mine of Wielitzka, near Cracow, 
 has been worked ever since 1251. There are three distinct 
 beds of salt, of which the uppermost is 200 feet below the sur- 
 face ; and the lower one about 800. The salt is extracted 
 chiefly from the lower bed, which is much purer than the 
 others. The excavations extend over a distance nearly two 
 leagues and a half in length ; and consist of galleries and 
 chambers of immense height, their roof supported by pillars of 
 salt left for that purpose. There are also three chapels in 
 various parts of the mine, where, on certain days, mass is per- 
 formed; all the altars, statues, and other ornaments being 
 carved in salt. 
 
SAL AMMONIAC — MERCURY. 
 
 115 
 
 Salt, in some countries, forms considerable hills above the 
 surface of the ground, as in Spain, where the town of Cardona 
 stands at the foot of a rock of salt above 300 feet high. It is 
 quarried out in the manner of building-stone, and is so pure 
 that it requires only to be crushed to powder. In Moldavia, 
 Persia, Affghanistan, and the North of Africa there are similar 
 hills, which appear to be generally on the borders of extensive 
 desert plains. 
 
 The springs which issue from saline strata afford, in many 
 countries, large quantities of salt, as at Droitwich, in Cheshire; 
 Dieuze and Chateau Salins, in France ; Schonbeck, in Magde- 
 burg, &c. The greater part of the salt made in the United 
 States is obtained in this manner. 
 
 Salt lakes also are numerous in several parts of the world ; 
 and the earth around them is generally impregnated with salt, 
 which in the dry season appears on the surface in the form of 
 an efflorescence. 
 
 3. Sal Ammoniac (Salmiac). A soluble salt characterised 
 by its sharp saline taste ; it occurs in volcanic regions, in the 
 form of a whitish crust or efflorescence ; sometimes, but rarely, 
 crystallized in octahedrons. It consists of chlorine and am- 
 monia, and before the blowpipe is entirely volatilized. 
 
 4. Sylvine, the chloride of potassium, has been observed in 
 the salt mines of Salzburg. 
 
 5 and 6. Chloruret op Calcium and of Magnesium 
 exist in the water of the seas and of salt lakes, with common 
 salt. 
 
 7. Horn Mercury (Chloruret of Mercury). This is the 
 same substance as calomel , and occurs in small quantity in some 
 quicksilver mines, either in small mammellated masses, or mo- 
 dified square prisms, which are transparent, with an adaman- 
 tine lustre. It is soft and waxy in its texture : specific gravity 
 6*5 ; and before the blowpipe is entirely volatilized. 
 
 Horn Silver (Corneous Silver Ore; Kerargyre). This 
 mineral is very similar in appearance to the last species ; but 
 the crystals, which are extremely rare, are cubes, either simple 
 
116 
 
 CERASITE — IODIDES, 
 
 or with the angles truncated. It forms small irregular masses 
 of a grey or brownish colour, or occurs as a thin crust on other 
 ores. It is translucent, soft, and sectile, with a specific gravity 
 of about 5. 
 
 In the European silver mines it is rarely met with ; but in 
 some parts of Mexico and Peru it forms a large portion of the 
 ores called pacos and colorados, in which it is mixed with earthy 
 oxyde of iron, and penetrated by numerous fine threads of 
 metallic silver. 
 
 9. Ceracite (Chloruret of Lead; erroneously. Muriate of 
 Lead). A scarce mineral, first discovered in the Mendip hills; 
 white or yellowish, nearly opaque and somewhat pearly ; spe- 
 cific gravity 7. 
 
 10. Corneous Lead Ore (Chloro-carbonate of Lead). A 
 transparent mineral, crystallizing in square prisms, with adaman- 
 tine lustre, which has been found near Matlock and in Germany. 
 Both this and the preceding species are rare ; reducible with 
 soda by the blowpipe. 
 
 11. Atacamite (Chloruret of Copper). In the desert of 
 Atacama, between Chili and Peru, this substance is found in 
 the form of a dark green sand : the grains are crystallized 
 more or less perfectly in rhombic prisms ; and some are very 
 brilliant and transparent. In Chili it is ground up and sold as 
 sand for letters, under the name of arsenillo . More recently it 
 has been found in Saxony, massive. 
 
 Family VII. — Iodides. 
 
 Iodine, which is a simple substance or element, is not found 
 uncombined. When obtained by art, it appears in the form of 
 black shining particles resembling plumbago, which, when 
 heated in a closed tube, volatilize and become an amethyst- 
 coloured vapour. 
 
 Iodine exists in combination with potassium and sodium, in 
 the water of some mineral springs, as at Ashby-de-la-Zouch. 
 
 Iodide of Mercury, of a brownish-red colour, has been ob- 
 served with some other Mexican ores. When prepared artifi- 
 
BROMIDES — FLUORIDES. 
 
 117 
 
 / 
 
 dally, and free from all impurity, it forms a red pigment, far 
 more brilliant than the common vermilion, but less permanent. 
 
 Iodide of silver, also, has been brought from Mexico ; of a 
 yellowish-white colour, and lamellar. 
 
 Iodide of zinc, from Silesia. 
 
 Family VIII. — Bromides. 
 
 Bromine, which, when obtained alone, is a dark brown 
 liquid, is contained in some mineral springs, and in the water of 
 the lake Asphaltites. 
 
 Family IX. — Fluorides. 
 
 The combinations of fluorine are few in number, and, except- 
 ing fluate of lime, are rare substances. 
 
 1. Fluorspar (Fluate of lime ; Fluoride of Calcium ; Fluo- 
 rite ; Fluorine ; Derbyshire spar) . This mineral is widely dis- 
 tributed in nature, and offers considerable variety and beauty 
 in its appearance. 
 
 Its colours are generally bright ; the crystallized fluor of 
 Durham and Yorkshire is most frequently violet with a tinge 
 of pale green, and perfectly transparent : in Derbyshire, speci- 
 mens have been raised of a fine clear topaz yellow, and also 
 colourless, often enclosing minute particles of copper pyrites, a 
 mineral which is very often found with it : the radiated fluor 
 from the same neighbourhood is generally amethyst, or deep 
 indigo blue. In Cornwall, and likewise in Saxony, fluorspar 
 of a bright green colour is often the chief veinstone of the 
 copper ores : it is seldom light blue or rose-coloured. 
 
 Fluor is crystallized most commonly in cubes, either simple, 
 or with the edges bevelled, or with a very low pyramid on 
 each face (figs. 1 and 12). Its cleavages, however, are 
 parallel to the faces of the regular octahedron, which must, 
 therefore, be regarded as its primary form, though octahedral 
 crystals rarely occur. 
 
 The specific gravity of fluorspar is 3*1 or 3*2; hardness 4, 
 
118 
 
 CRYOLITE — FLUCERINE. 
 
 scratching calcspar with ease. When moderately heated, it 
 becomes phosphorescent ; some varieties shining with a purple, 
 others with a blue, yellowish, or green light. Chlorophane is a 
 name given to a kind that, when heated, exhibits a brilliant 
 green colour ; this variety is found in Saxony. 
 
 Fluorspar may be dissolved in sulphuric acid ; by this pro- 
 cess, the fluorine is disengaged ; a gaseous acid which has the 
 power of corroding glass, and even siliceous stones. 
 
 Massive fluor with a coarsely fibrous or columnar structure, 
 is abundant in Derbyshire ; this is the kind chiefly used for 
 making vases and other ornamental objects : it is generally 
 turned in a lathe ; but great care is requisite, on account of its 
 brittleness. 
 
 The colours of this are sometimes rendered more brilliant 
 by heating the fluor. It has so much resemblance both in 
 colour and structure to some varieties of amethyst, that these 
 vases have often been sold under the denomination, root of 
 amethyst: and it is conjectured that the celebrated Murrhine 
 vases of antiquity were formed of the same substance. 
 
 Blue John is a name given by the Derbyshire miners to mas- 
 sive fluor of an intense blue, which becomes violet when mode- 
 rately heated. 
 
 2. Cryolite. This mineral, which has hitherto been found 
 in Greenland, is generally of a pure white colour, translucent, 
 and cleavable into rectangular prisms : it is characterised by 
 melting in the flame of a candle.* It is a fluate of alumina 
 and soda. 
 
 3. Fluate of Cerium (Flucerine). A rare mineral which 
 occurs at Brodbo in Sweden, in small irregular masses of a 
 pale violet colour, opaque, and with very little lustre. Consists 
 of Fluoric acid and Cerium. 
 
 Basicerine , which contains a larger proportion of cerium, is 
 of a yellowish colour and crystalline structure. 
 
 4. Yttrocerite is another combination of cerium and fluoric 
 acid with yttria and lime : its colour is grey, reddish, or violet; 
 
 * Its name is derived from Jcruos , ice, in allusion to this property. 
 
SELENIDES TELLURURETS. 
 
 119 
 
 texture compact ; scratches fluorspar. This also occurs only 
 in Sweden. 
 
 Family X. — Selenides. 
 
 Selenium, which resembles sulphur in some of its properties, 
 is found in combination with a very small number of metals : 
 they all have a metallic lustre ; and are characterised by emit- 
 ting, when heated, a strong smell of hore-radish. 
 
 Clausthalite, the seleniuret of lead, is very much like galena : 
 it occurs at Clausthal, in the Hartz. 
 
 A variety, of a yellowish colour, contains also copper. 
 
 Eukairite , composed of selenium, silver, and copper, is found 
 disseminated in the calcareous rocks of Smoland, in Sweden. 
 
 Seleniuret of silver and of zinc are said to have been found 
 in very small quantity in Mexico. All these minerals are very 
 rare. 
 
 Family XI. — Tellurides. 
 
 Tellurium occurs in the native state, and alloyed with other 
 metals. 
 
 Native Tellurium has a lamellar or granular structure 
 and metallic lustre. It is white or very pale grey, and is said 
 to be sometimes crystallized in hexagonal prisms. It is easily 
 fused, and volatilized by the blowpipe, and differs from arsenic 
 and selenium in emitting no odour when heated. When pure, 
 its specific gravity is 6*1, but it often contains a small quantity 
 of other metals. 
 
 Tellurium is found chiefly in Transylvania, where also most 
 of its combinations occur, in little veins dispersed through the 
 earthy depositories of galena, red silver ore, gold, &c. 
 
 Tellururets. 
 
 1. Graphic Tellurium (Graphic Gold; Sylvan). The 
 crystals of this alloy, when perfect, are prisms of four or six 
 sides, modified by smaller planes ; but they are always small, 
 often acicular, and grouped together so as to present a resem- 
 blance to some oriental written characters. 
 
120 
 
 PHOSPHATES. 
 
 It is obtained at Nag-y-ag and at OfFenbanya, where it is 
 worked as an ore of gold, of which it contains 30 per cent., with 
 10 of silver, and 60 of tellurium. When fused by the blow- 
 pipe, the tellurium is volatilized, and a small globule of a pale 
 yellow colour remains, which is a mixture of gold and silver. 
 
 2. Telluric Silver (White Tellurium; Mullerine). This 
 likewise contains both gold and silver ; of the former 26 per 
 cent. ; but they are combined with lead as well as tellurium : 
 crystals, which are very rare, are modified rectangular laminae . 
 
 This, like the preceding Graphic species, is sought for as a 
 gold ore. 
 
 3. Tellururet of Lead (Black Tellurium ; Elasmose) oc- 
 curs in small lamellar crystals heaped confusedly together : it 
 is of a dark grey colour, and is often accompanied by the rose 
 manganese of Nag-y-ag. 
 
 It contains a few per cent, of gold. 
 
 Family XII. — Phosphorides. 
 
 The natural combinations of phosphorus are phosphates : 
 the phosphoric acid is found combined with several of the 
 earths, and the oxydes of some other metals. 
 
 Phosphates. 
 
 1. Apatite (Phosphate of lime ; Phosphorite). This mine- 
 ral so strongly resembles, in its appearance, several others, that 
 it received its name from the Greek word 
 apataOy I deceive. It crystallizes in hexago- 
 nal prisms, which are sometimes modified on 
 the edges or the angles, or on both. The 
 crystals are vitreous, transparent or translu- 
 cent, and sometimes very bright: those which 
 are of a bluish or green colour might easily be mistaken, at 
 first sight, for beryls : some are colourless, violet, or lilac, and, 
 if not distinctly crystallized, appear extremely like fluorspar. 
 Apatite, however, is harder than fluorspar, and is not cleavable, 
 but breaks with a conchoidal fracture : on the other hand, it is 
 
 No. 58. 
 
 ^ ^ 
 
 
 
WAVELLITE. 
 
 121 
 
 less hard than beryl, being No. 5 in the scale of hardness, and 
 heavier; specific gravity 3*1 : it is soluble in nitric acid; and 
 becomes phosphorescent when heated. 
 
 Asparagus stone is apatite of a greenish yellow colour, from 
 Tyrol, where the crystals are embedded in talc. 
 
 Moroxite is a name given to bluish-green crystals from 
 Arendahl, in Norway. 
 
 Phosphorite is opaque, and white or yellowish white : when 
 broken it shows a sort of feathery structure, and numerous 
 small cavities. This variety is massive, and at Logrosso, in 
 Estramadura, forms entire hills ; it is there used as a building 
 stone. In Hungary, phosphorite occurs of a loose earthy 
 texture. 
 
 Apatite is a scarce mineral in England : small crystals have 
 been found in decomposing granite near St. Austle, in Corn- 
 wall ; and fine groups of a larger size, with tourmalines, near 
 Chudleigh, Devonshire. Fine specimens are obtained from 
 the metalliferous veins of Bohemia, Moravia, and Saxony, and 
 from the rocks of St. Gothard. 
 
 2. Wavellite (Hydrargillite) occurs in small globular or 
 semi-globular masses, seldom exceeding half or three quarters 
 of an inch in width, attached to 
 the surface of slate and other 
 rocks. They consist of minute 
 crystals diverging from a centre, 
 and when broken exhibit this 
 radiated structure and a bright 
 glassy lustre. The colour is most 
 frequently greyish or greenish white, but it has been found in 
 Scotland of a dark green colour. 
 
 Wavellite is a phosphate of alumina combined with water 
 and a very small quantity of the fluate of alumina. It was first 
 discovered near Barnstaple, in Devonshire, by Dr. Wavel, and 
 it occurs in a similar situation at Dumbarton, and near Cork. 
 It is found also at Freiberg in Saxony, in Bavaria, and at 
 several places in the United States. 
 
 G 
 
 No. 59. 
 
122 
 
 WAGNERITE VIVIANITE. 
 
 3. Bluespar (Azurite; Klaprothine). This mineral has 
 been confounded with lapis lazuli, but the blue colour inclines 
 less to purple ; its specific gravity is 3, and it is infusible, losing 
 its colour, however, before the blowpipe. It is a phosphate of 
 alumina and magnesia, and is found principally in Styria, em- 
 bedded in micaceous and quartz rocks. 
 
 The Turquoise , to which fashion has attached so high a value, 
 appears to be nearly the same substance in composition as blue- 
 spar, except that it contains a very small quantity of copper, to 
 which it owes its greenish blue colour. It occurs in small re- 
 niform masses, embedded in veins which traverse a mountain- 
 ous district of Khorassan, near Nishapur and Firozkuh ; also 
 in rolled pebbles.* 
 
 4. Wagnerite, a fluo-phosphate of magnesia, occurs at 
 Salzburg, in yellowish or greyish white oblique prisms : about 
 as hard as apatite : rare. 
 
 Phosphates of Iron. 
 
 5. Vivianite. When crystallized it is perfectly transpa- 
 rent, vitreous, or somewhat pearly, and of a deep blue colour. 
 
 The crystals are oblique prisms, variously modified, and 
 easily cleavable in one direction, parallel to their axis. It is 
 tender, and scratched with ease by calcspar ; specific gravity 
 2*66. It sometimes forms radiated nodules, and occurs also in 
 opaque earthy masses, resembling lumps of common indigo. 
 
 Vivianite consists of phosphoric acid 31 T 8, protoxyde of 
 iron 41*23, and water 27*49. When pulverized, it may be 
 fused into a scoria attractable by the magnet. 
 
 This mineral was first discovered in Cornwall, and has since 
 been found at Bodenmais in Bavaria, in Transylvania, and the 
 United States. 
 
 * In the South of France, and some other countries, semi-fossil ivory 
 and bones are found, coloured by phosphate of iron, which resemble the 
 oriental turquoise in colour and hardness : but when burnt, they exhale a 
 foetid smell of animal matter, and are said to lose their colour by exposure 
 to damp. This is called by jewellers turquoise de nouvelle roche ; the 
 other, turquoise de vieille roche. 
 
COPPER PYROMORPHITE. 
 
 123 
 
 Anglarite , of a leek-green colour, contains less phosphoric 
 acid than vivianite ; it has been observed at Limoges. 
 
 Kakoxene , a phosphate of iron with alumina and silica, is a 
 mineral of a bright straw-yellow colour, which occurs in radiated 
 tufts of silky fibres in iron ore, in Bohemia. 
 
 Triphylline , Triplite , and Hureaulite are phosphates of iron 
 and manganese, which are disseminated in small crystals in the 
 rocks of Limousin. 
 
 6. Phosphate of Copper. There are two kinds of this 
 mineral ; one has been found in Cornwall and at Libethen (in 
 Hungary), in small crystals of an intense green colour, which 
 are rectangular octahedrons ; they are generally bright, and 
 sometimes quite black externally, but the powder is a clear 
 bright green. 
 
 Pseudomalachite , the phosphate of Rheinbreitherch, has the 
 same dark green colour ; but it forms radiated masses, and in- 
 crustations of slender prismatic crystals, closely pressed to- 
 gether. Both afford water by calcination. 
 
 7. Pyromorphite (Phosphate of lead). A beautiful mineral 
 which occurs in the lead mines of various countries, though not 
 abundantly. Its colour varies from bright grass-green to yel- 
 low, orange, brown, and sometimes a dull violet. It occurs in 
 clusters of hexagonal prisms, occasionally terminated at each 
 end by alow pyramid, or modified as No. 58, p. 120; or as 
 an incrustation resembling moss. The crystals have generally 
 a greasy lustre, but are sometimes very brilliant, and mostly 
 translucent; specific gravity 7. 
 
 Pyromorphite undergoes a change by fusion, which is pecu- 
 liar to it : the melted globule in cooling becomes angular, and 
 assumes a polyhedral form. 
 
 Most specimens contain 9 or 10 per cent, of the chloruret of 
 lead ; sometimes, arseniate ; and those of an orange colour, 
 some chromate of lead. Fine specimens are obtained from the 
 lead mines of Durham, of Leadhills, Brittany, the Hartz and 
 other European localities ; besides several places in the United 
 States, particularly the Perkiomen lead mine near Philadelphia. 
 
 G 2 
 
124 
 
 URANXTE ARSENIC — ARSEN XU RETS. 
 
 8. Uranite (Phosphate of Uranium; Uran mica). The 
 lamellar structure of this mineral, somewhat resembling mica, 
 joined to its brilliant yellow or green colour, distinguishes it 
 from all others. When crystallized, it appears in square or 
 octagonal tables, sometimes modified by narrow planes on the 
 edges of the base. The yellow uranite consists of phosphate of 
 uranium and lime, with 15 per cent, of water: in the green 
 uranite (Chalkolite), of which splendid specimens are obtained 
 from some of the tin and copper mines of Cornwall, the lime is 
 replaced by copper : it is found also in Saxony and Bohemia. 
 
 Family XIII. — Arsenides. 
 
 Arsenic is found in the metallic state, both alone and form- 
 ing alloys, which are arseniurets ; its oxyde, also, producing 
 several arseniates ; but the greater part of all these species are 
 scarce and unimportant substances. 
 
 Genus I. Arsenic. 
 
 When freshly broken, arsenic is nearly white, with a bright 
 metallic lustre ; but after being exposed for a short time to 
 the air it becomes very dark grey, in consequence of tarnishing. 
 It is brittle, and when struck produces a ringing sound. It is 
 almost entirely volatile by heat, giving off a strong odour of 
 garlic. 
 
 Native arsenic is found in many of the localities of nickel and 
 cobalt ores ; and in Norway crystallized beryls are sometimes 
 embedded in it. 
 
 Genus II. Arseniurets. 
 
 1. Smaltine (Tin white Cobalt; Arsenical cobalt). Its 
 crystallizations are the same as those of Galena, and do not 
 exhibit the dodecahedral modifications of cobalt glance, from 
 which it is further distinguished by its pale grey colour : the 
 faces of the crystals are generally convex and intersected by 
 irregular cracks ; it is also massive, and reticulated. 
 
 It consists essentially of arsenic and cobalt, the quantity of the 
 
KUPFERNICKEL OXYDE OF ARSENIC. 
 
 125 
 
 latter varying from 1 8 to 26 per cent. A great part of the smalt 
 of commerce is manufactured from this ore, which is obtained 
 abundantly in Saxony and Bohemia ; it is met witlj also in 
 several other parts of Europe, but in less quantity. 
 
 2. Kupfernickel (Arsenical Nickel). A metallic substance 
 of a reddish colour and rather brittle, which is found in many 
 of the localities of the cobalt ores. Its solution in nitric acid 
 is green, but becomes violet blue by the addition of ammonia. 
 Specific gravity 7 to 7*6. 
 
 From this ore is obtained the nickel used for chemical pre- 
 parations, and in the different alloys called German silver and 
 nickel silver ; some of these contain 25 per cent, of nickel, 
 combined with zinc and copper. The white copper of the 
 Chinese is a similar alloy, containing 31 per cent, of nickel. 
 
 3. Arsenical Silver is distinguished from native silver by 
 its brittleness, and the arsenical fumes when heated : it occurs 
 in the Hartz. 
 
 4 and 5. Arsenical Antimony occurs in the Dauphine and 
 the Hartz: Arsenical Bismuth, in the silver mines of 
 Schneeberg : both are rare. 
 
 Genus III. Oxyde of Arsenic. 
 
 White Arsenic (Arsenious acid; Arsenic bloom). This 
 is the same substance as the arsenic of the shops, and is found 
 either in the form of a white powder, or in small compact 
 masses (very rarely) crystallized in octahedrons and tetrahe- 
 drons. 
 
 It has been thought to be a result of artificial heat, in conse- 
 quence of refining operations carried on in the mines ; or of 
 some natural conflagration that has occurred in them. 
 
 Genus IV. Arseniates. 
 
 1. Arseniate of Lime (Pharmacolite). When pure, this 
 substance is white, but it is often of a rose colour, from a mix- 
 ture of arseniate of cobalt ; occurs in delicate acicular crystals 
 aggregated in small parcels, or small hexagonal prisms. It is 
 
126 
 
 COBALT — LEAD — COPPER. 
 
 distinguished from the preceding substance by not being 
 wholly volatile. 
 
 2. Arseni ate of Cobalt (Erythrine). Of a crimson, or 
 rose colour, approaching to violet ; sometimes crystallized in 
 oblique prisms, but oftener in small masses of a botryoidal 
 form, with a fibrous structure. It is found with ores of cobalt, 
 and with arsenical minerals. 
 
 3. Nickel Ochre. The arseniate of nickel is of a green 
 colour, pulverulent, or in delicate filaments : it often accom- 
 panies Kupfernickel. 
 
 4. Arseniate of Lead (Mimetese). It takes the same 
 form as the phosphate of lead, but the prisms are often swelled 
 in the middle, so as to have something of a barrel shape: 
 colour, generally pale yellow-brown, and lustre often silky. It 
 is found in Cornwall and some other mining districts. 
 
 Arseniates of Copper. 
 
 There are several species of this ore, which resemble each 
 other in giving off alliaceous fumes when heated, and, if dis- 
 solved in nitric acid, depositing copper on any piece of iron 
 dipped into it. Hardness, in general, 3 to 4. 
 
 5. Copper mica (Erinite) occurs in thin transparent crys- 
 tals resembling laminae of mica, which are hexagonal and of a 
 deep emerald-green. It contains 59 per cent, of oxyde of 
 copper, with arsenious acid, and water. 
 
 6. Liroconite (Lenticular copper ore). In general, it is 
 easily distinguished by its light greenish blue colour, and the 
 form of its crystals, which are rectangular octahedrons, very 
 obtuse, sometimes with the edges truncated. This species con- 
 tains 35 per cent, of water. 
 
 7. Oliven Ore (Right prismatic arseniate). The colour 
 of this mineral is yellowish or olive-green of various shades : 
 crystals are sometimes nearly black ; they occur in little tufts 
 on quartz, or as a velvety coating. 
 
 Wood copper is a name given to specimens of this ore, which 
 have a fine fibrous texture and brownish colour : some of these 
 are very soft, and may be reduced to powder by the fingers. 
 
CUBE ORE — SAPPHIRE. 
 
 127 
 
 8. Trihedral Oliven Ore (Aphanesite) resembles the 
 preceding species in its general appearance ; but the crystals are 
 derived from an oblique prism, and most usually their trihedral 
 points only are visible. 
 
 All these species are found in some or other of the Cornish 
 mines : Liroconite appears to be peculiar to them. 
 
 Copper froth contains about 13 percent, of carbonate of lime. 
 
 Euchroite , of a fine green colour, and Condurrite, of a 
 brownish black, are also arseniates of copper. 
 
 Arseniates of Iron. 
 
 9. Cube Ore (Pharmacosiderite) occurs in very small cubic 
 crystals of a dark green colour, and usually with bright faces : 
 the cubes often have the alternate angles truncated, like the 
 crystals of boracite (No. 46, p. 73). From the mines of Corn- 
 wall, France, and Saxony, where it is found with brown haema- 
 tite and copper ores. 
 
 Skorodite* in minute, bluish, transparent crystals from the 
 same localities ; it contains less water than the preceding 
 species. 
 
 Second Class. 
 
 Leucolytes. 
 
 The elements which are the types of families in this class, 
 are susceptible of forming colourless solutions. 
 
 
 Family I. — Aluminides. 
 
 The earth alumina occurs uncombined, and also as the mine- 
 ralizing element of spinel, and some few other substances. 
 
 1. Sapphire. This beautiful gem, which, next to the dia- 
 mond, is the hardest substance in nature, is pure alumina. It 
 crystallizes in forms belonging to the rhombohedral series ; 
 generally hexagonal prisms and double pyramids, and present- 
 ing few additional planes. The primary rhombohedron, which 
 is very slightly acute, may sometimes be obtained by cleavage ; 
 
 * Skorodon, garlic. 
 
128 
 
 CORUNDUM EMERY. 
 
 but sapphire, being very tenacious as well as hard, often breaks 
 with a conchoidal fracture. Its specific gravity is 3*9 to 4*1. 
 
 The most usual colours of the sapphire are blue and bluish 
 grey ; when it is of a clear rose or crimson colour, it is called 
 oriental ruby ; when yellowy oriental topaz ; if purple, oriental 
 amethyst; and if green, oriental aquamarine or chrysolite , ac- 
 cording to the tint ; but it is easily distinguished from all the 
 stones whose names it bears, by its great hardness and weight. 
 The term oriental , it must be observed, is usually applied in jew- 
 ellery, to the hardest and most valuable kinds of gems, without 
 regard to their chemical nature. 
 
 Some sapphires, when polished with a rounded surface at 
 right angles to the axis of the crystal, exhibit a luminous 
 chatoyant star of six rays, and are called asterias; this appear- 
 ance occurs oftener in the blue and white, than in the other 
 varieties, and is quite independent of their degree of trans- 
 parency ; some asterias being perfectly transparent, and others 
 faintly translucent. 
 
 Corundum is a less pure variety of the same substance, con- 
 taining a small amount of oxyde of iron and 
 some silica. Crystals of corundum, similar 
 to those of sapphire, are found of a large 
 size ; but the faces are often very irregular, 
 and rarely smooth and bright as in most hard 
 crystalline minerals. It is more easily cleav- 
 abfe than the sapphire ; and generally of a 
 dark grey colour. 
 
 Emery is corundum in a granular form, 
 and of a dark iron-grey or brownish colour. 
 
 Some bluish varieties, translucent and com- 
 pact, have been called diamond spar , or adamantine spar . 
 
 The finest blue sapphires are brought from Ceylon, where 
 they are found, more or less rounded, in the sand of certain 
 localities with hyacinths : the best oriental rubies come from 
 the Capelan mountains near Syriam, in the kingdom of Ava. 
 Corundum, both crystallized and in irregular masses, is found 
 
GIBBSITE — SPINEL RUBY. 
 
 129 
 
 embedded in granite in various parts of India and China : 
 beautiful crystals, also, of a clear blue and rose colour, are 
 sometimes obtained from the dolomite rocks of Mount St. 
 Gothard. 
 
 Emery is found in many countries, generally in scattered 
 masses which appear to have been brought from a distance and 
 worn away by the action of water : in this condition it occurs 
 in Jersey, the Islands of the Grecian Archipelago, and Eastern 
 Prussia. It is much employed in the form of powder, for 
 polishing the surface of metal and glass, and cutting the softer 
 precious stones, such as the emerald and amethyst. 
 
 2. Gibbsite (Hydrate of alumina). A white or greenish 
 mineral occurring in stalactitic and mammellated forms, of a 
 white or greenish colour : it consists of 64*8 alumina, and 34*7 
 water, thus bearing the same relation to corundum, as opal to 
 quartz. Found in iron ore in Massachusetts. 
 
 Diaspore contains less water, and occurs in slender and 
 brilliant greenish prisms, embedded in the limestor^e of the 
 Ural Mountains. Wavellite was at first confounded with this 
 substance and received the same name, before its composition 
 was known. 
 
 Aluminates. 
 
 1. Spinel (Spinel ruby; Balas ruby). The spinel ruby 
 differs considerably from the red sapphire, or oriental ruby : it 
 crystallizes in octahedrons, which are sometimes modified 
 (figs. 5 and 10), and often macled (No. 19, p. 11). It is 
 rather less hard than the sapphire, but scratches topaz ; specific 
 gravity 3*7. Consists principally of alumina combined with 
 magnesia. 
 
 The fine red colour for which the ruby is esteemed, is 
 derived from a small quantity of chromic acid ; but spinels are 
 often colourless, yellowish, pale green and blue, and dark violet 
 and brown : the light colours are transparent, the dark ones 
 nearly opaque. 
 
 Jewellers give the name spinel generally to those stones 
 which have a colour approaching to scarlet ; they call the paler 
 
 G 5 
 
130 
 
 PLEONASTE — BRXJCITE. 
 
 ones, balas ruby ; and those which incline to an orange tint, 
 they denominate rubicelle. 
 
 The crystals of spinel occur with those of sapphire and 
 hyacinth, in the beds of streams, among sand and pebbles 
 which appear to be the debris of granitic and micaceous rocks, 
 principally in Ceylon ; where they are also met with embedded 
 in granular limestone. 
 
 The Balas rubies were brought formerly from the province 
 of Balachan, in Usbec Tartary, where they were found of great 
 beauty and value : Marco Polo makes mention of them and 
 says, that the rubies of Balachan were monopolized by the 
 Sovereign, who, in order to enhance their price, prohibited the 
 working of the mines. 
 
 Pleonaste or Ceylanite , in small black brilliant octahedral 
 crystals, is abundant in some of the micaceous rocks ejected 
 from Vesuvius : a variety of a brown colour and without lustre 
 is found at Laach, on the Rhine. Pleonaste contains from 16 
 to 20 per cent, of oxyde of iron. 
 
 Automolite resembles spinel in hardness and crystallization ; 
 but the magnesia is replaced by oxyde of zinc. It has a higher 
 specific gravity, 4*6, and its colour is generally dark iron- 
 grey. At present it is found only in Sweden and in New 
 Jersey. 
 
 2. Plombgomme (Aluminate of lead). A substance con- 
 sisting chiefly of alumina, lead, and water, which has the ap- 
 pearance of yellowish gum, but scratches fluorspar. It occurs 
 in some lead mines of Huelgoat, in Brittany. 
 
 Family II. — Magnesides. 
 
 Brucite (Hydrate of Magnesia). This mineral resembles 
 in its appearance the most beautiful varieties of white pearly 
 talc ; but as it consists wholly of magnesia and water it is 
 entirely soluble in the acids, without effervescence : this 
 character distinguishes it also from the transparent lamellar 
 gypsum. 
 
TINSTONE STREAM TIN. 
 
 131 
 
 It has been found in serpentine in New Jersey, and Unst, 
 one of the Shetland Isles. 
 
 Family III. — Stannides. 
 
 Tin is not found in the metallic state. 
 
 Oxydes. 
 
 Tinstone (Cassiterite). The oxyde of tin is its chief ore, 
 and the one from which all the tin used in the arts and manu- 
 factures is obtained. 
 
 When pure, it is colourless and transparent : but it is much 
 oftener brown, sometimes black, from the 
 oxyde of iron it generally contains. The 
 crystals are derived from a square prism ; 
 figs. 20, 23, 24, are the most common; a 
 made or twin crystal of fig. 20 also occurs 
 frequently, as here represented, and a similar 
 combination of fig. 23. In hardness it is always equal to 
 quartz, scratching glass and felspar ; and when scratched or 
 pulverized, the streak and powder are always white. Its 
 specific gravity is 6*5 to 7, which is nearly as high as that of 
 metallic tin. 
 
 Tinstone is sometimes massive and granular; in the latter 
 case, it is much intermixed with quartz, the usual veinstone of 
 tin ore ; crystals of tourmaline, apatite, fluorspar, and topaz 
 are also found in tin veins ; the latter, particularly in Saxony, 
 and occasionally in Cornwall : chlorite also is abundant in tin 
 veins. 
 
 Stream tin consists of rolled fragments of tinstone, and 
 grains of various sizes intermixed with bits of rock, sand, and 
 pebbles, in the beds of streams and other low grounds. This 
 ore is collected for smelting ; and being separated from the 
 earthy matter with which it is intermixed by washing in a 
 stream of water, the places where this operation is carried on, 
 are called stream-works, and the ore itself stream-tin. In some 
 of these localities, grains of gold are found mixed with the tin. 
 
 No. 61. 
 
132 
 
 WOOD TIN NATIVE MERCURY. 
 
 Wood tin is the same substance occurring in pebbles or 
 nodules, with a compact fibrous structure, generally of a light 
 brown colour and variegated with dark and yellowish concentric 
 bands : those which exhibit dark spots or rings on the surface 
 are sometimes called toad's -eye-tin. 
 
 Tinstone is an ore found in many parts of the globe, but 
 there are few in which it exists in great quantity. The Cornish 
 mines are by far the most productive in Europe, affording 
 probably ten times as much as all the others. They were 
 explored and worked by the ancient inhabitants of Britain, 
 who traded in this ore with the Phoenicians, afterwards with 
 the Greeks established at Marseilles, and still more lately with 
 the Romans, who took much trouble to find out whence their 
 predecessors had obtained tin. 
 
 Next to Cornwall, the greatest quantity of tin is obtained 
 from the mines of Malacca and the Island of Banca : and in 
 Europe, principally in Bohemia and Saxony, whence some of 
 the finest crystallized specimens are obtained. 
 
 The uses of tin are numerous : the ease with which it may 
 be alloyed with other metals, or spread thinly over them — its 
 brightness, ductility, and the important property of not rusting 
 by exposure to the air, or by the contact of liquids — render it 
 highly advantageous as a coating for various kinds of vessels, 
 particularly those employed in cooking : copper vessels thus 
 coated were sometimes used by the Romans, as we learn from 
 Pliny, though they were by no means common. 
 
 Tin is requisite in the preparation of a fine scarlet dye, and 
 some of the crimson and purple colours used in glass-staining. 
 
 Family IV. — Hydrargyrides. 
 
 1. Native Mercury (Quicksilver). Globules of this metal 
 are often attached to masses of cinnabar, and it is found occa- 
 sionally in larger quantity in cavities of the veins. Some- 
 times it is dispersed through the cinnabar, and oozes from it 
 on being gently heated. 
 
NATIVE AMALGAM NATIVE SILVER. 
 
 133 
 
 The appearance of metallic mercury is well known ; its pro- 
 perty of remaining fluid at ordinary temperatures distinguishes 
 it from all other metals, which are rendered liquid only by the 
 application of heat. Mercury, therefore, to become solid, 
 must be exposed to a degree of cold far greater than that 
 which we experience in this climate ; at 39° below zero of 
 Fahrenheit it becomes solid, and is then malleable. 
 
 Mercury unites readily with several other metals, for which 
 reason it is used in the extraction of gold, and sometimes of 
 silver, from their ores. The recent discovery of cinnabar in 
 Upper California will therefore be eminently useful in that 
 region ; and fluid mercury will probably be found with it, as 
 well as in other parts of Mexico. With tin it forms the 
 amalgam or silvering for the backs of mirrors. In the native 
 state it is sometimes found combined with a small quantity of 
 silver. 
 
 2. Native Amalgam (Argentiferous Mercury). In appear- 
 ance, it exactly resembles silver, crystallizing in some of the 
 same forms (figs. 3 and 9), but with little lustre. It is softer 
 than silver, and much heavier ; specific gravity 14. This also 
 is found with cinnabar, but is a rare substance. 
 
 Family V. — Argyrides. 
 
 Native Silver. Like the silver of commerce, this is a 
 white malleable metal, rather harder than 
 gold, with a specific gravity of 10*3, to 
 10*5 : it is equally liable to become 
 tarnished, and it happens sometimes that 
 in consequence of cavities in the veins, 
 or from the silver lying near the surface 
 of the earth, it is somewdiat tarnished in 
 the mine : the streak, however, is always 
 silver-white. Its crystals belong to the 
 cubic series, and are most frequently octahedral, but without 
 any trace of cleavage. The crystals are frequently grouped in 
 
 No. 62. 
 
134 
 
 NATIVE LEAD. 
 
 rows, crossing each other at right angles, not unlike the 
 branches of some kinds of fir-tree. It often occurs in wiry 
 filaments and moss-like tufts, less commonly in leaves or 
 plates, and sometimes in solid masses of great size, both in 
 Europe and America. The silver mines of Kongsberg, in 
 Norway, have produced blocks weighing 5001b. and upwards: 
 and at Schneeberg, in Saxony, a large and rich vein was dis- 
 covered in 1478, and a block was cut from it, chiefly of metal, 
 of such size, that Duke Albert of Saxony descended into the 
 mine and made use of it as a dining table : it was afterwards 
 smelted, and produced 44,000 lb. of silver. In the United 
 States, silver is found associated with native copper in the 
 mines of Lake Superior, and often penetrating it ; and in 
 Mexico and Peru it is frequently intermixed, in the form of 
 small particles and fine threads, with the chloruret of silver 
 and iron ochre. Quartz and calcspar are the earthy minerals 
 most frequently found with it. 
 
 Native silver has been obtained from some of the Cornish 
 mines, but in very small quantity : indeed, there seem to be few 
 countries in which this metal, or some of its ores, is not met 
 with. A good deal was, at one time, raised in Scotland and 
 coined : and there are mines in France which still yield a con- 
 siderable quantity. In the plain called the Pampa de Navar, 
 filaments of silver are often found adhering to the roots of the 
 grass. The silver ores of South America, however, are said 
 to be in general far less rich in metal than those of Europe ; 
 and are more productive, only because they exist there in larger 
 quantity, and are more extensively worked. 
 
 Family VI. — Plumbides. 
 
 Native Lead. A substance of rare occurrence. It has 
 been observed in small grains and laminae in some volcanic 
 products, and also, it is said, in specimens of galena from 
 Alston Moor. It may be distinguished by its softness and 
 sectility from the galena, which is hard and brittle. 
 
LEAD ANTIMONY SILVER. 
 
 135 
 
 Oxydes of Lead. 
 
 1. Minium (Red Oxyde of Lead). A red substance, oc- 
 curring in the form of powder in some veins of galena and 
 calamine. It is the same substance as the red lead used in 
 painting ; but for this and other purposes it is prepared artifi- 
 cially. 
 
 2. Yellow Oxyde of Lead (Native litharge). This 
 lead ore, which is less oxydized than the preceding species, 
 occurs sometimes as a powder, sometimes in solid masses, not 
 unlike yellow jaspar ; its great weight distinguishes it from all 
 minerals which otherwise resemble it. 
 
 Family VII. — Antimonides. 
 
 Native Antimony. A metal of silver- white colour and 
 brilliant lustre, which is found in small masses, with some arse- 
 nical and antimonial ores, as in Dauphine and the Hartz. It 
 may be distinguished from native silver by its octahedral cleav- 
 age, though it does not crystallize ; and by evaporating before 
 the blowpipe in white fumes. 
 
 Antimonuret. 
 
 Antimoni al Silver (Discrase). White and rather brittle : 
 distinguished from the preceding by affording a globule of 
 silver by the blowpipe. 
 
 Oxydes of Antimony. 
 
 1. White Antimony (White Oxyde of Antimony) occurs 
 in small lamellar masses, with a perfect rectangular cleavage. 
 It is sometimes yellowish white, and has a somewhat pearly 
 lustre: soft and extremely fragile: specific gravity 5*57: 
 fusible in the flame of a candle. It is found in very small 
 quantity with other ores of antimony. 
 
 Earthy white antimony is the same oxyde combined with 
 water, which occurs as a powder on the grey antimony ore. 
 
 2. Red Antimony Ore (Kermes). A compound of the 
 oxyde and sulphuret of antimony, which has a dull crimson 
 
136 
 
 SPARTALITE. 
 
 colour. It forms tufts of delicate acicular crystals, sometimes 
 radiating, sometimes interlaced, and as fine as hairs. It is 
 scratched by almost all other minerals. It is at present a 
 scarce substance, met with occasionally on the surface of grey 
 antimony ore, and among the ores of arsenic ; hut which, if 
 found abundantly, would be a profitable mineral. 
 
 Family VIII. — Zincides. 
 
 The principal ores of zinc have been described in the families 
 carbonate , sulphuret, &c., to which they belong. It is never 
 found in a metallic state : but we are acquainted with an oxyde 
 which is now wrought as a zinc ore. 
 
 Spartalite (Red Oxyde of Zinc). It occurs in lamellar 
 masses and grains of a fine deep red colour, and brilliant lustre, 
 strongly translucent ; or in thin fragments, transparent. Hard- 
 ness between 4 and 5, scratching red copper and red silver ore. 
 With borax it fuses to a yellow transparent glass. 
 
 Spartalite is found embedded in iron ore at Sparta, New 
 Jersey, and at Franklin in the same State. 
 
 Family IX. — Bismuthides. 
 
 This family contains only native bismuth and the oxyde of 
 bismuth. 
 
 Native Bismuth. A metal of a reddish white colour, 
 lamellar, and cleavable parallel to the planes of the octahedron : 
 sometimes it appears in the form of a crystalline arborescence ; 
 specific gravity 9*7. When heated by the blowpipe, bismuth 
 evaporates, and is converted into an oxyde which is deposited 
 as a yellow powder on the charcoal. 
 
 It is not a very abundant metal ; but a quantity sufficient 
 for the few purposes to which it is applied, is obtained from the 
 mines of Saxony and Bohemia, where it is found principally in 
 the veins that afford red silver and cobalt ores. It has been 
 met with in some of the Cornish mines, but in very small 
 quantity. 
 
BISMUTH RUTILE. 
 
 137 
 
 Bismuth has been sometimes employed in the fabrication of 
 type metal ; but one of its principal uses is in making solder ; 
 being fusible at a lower heat than any other metal, it imparts 
 this property to its alloys. Teaspoons made of a compound of 
 8 parts of bismuth, 5 of lead, and 3 of tin, will melt on boiling 
 water being poured on them. 
 
 Oxyde of Bismuth. 
 
 Bismuth Ochre occurs in the form of a yellow powder in 
 the localities of native bismuth. 
 
 Third Class. 
 
 Chroicolytes. 
 
 The types of this class are solid and metallic substances, all 
 of which are capable of forming coloured solutions in acids. 
 
 Family I. — Titanides. 
 
 Metallic titanium is not ascertained to exist in nature ; it has 
 been found in iron slags and old blast furnaces, in the form of 
 small cubes of a bright copper colour. 
 
 Oxydes. 
 
 1. Rutile (Titanite; Oxyde of Titanium). Generally of a 
 dark cherry-red ; when it contains iron, passing n 0 g 3 # 
 to brown, with a sub-metallic lustre ; but the 
 purer varieties are of a bright red, and transpa- 
 rent. Its crystals are right prisms of eight or 
 twelve sides, seldom with perfect terminations ; 
 jointed crystals sometimes occur, composed of 
 two or three of these. 
 
 It is brittle, about as hard as felspar ; and the specific gra- 
 vity 4*25, which, together with its distinct lateral cleavage, 
 will distinguish it from red schorl and some other minerals. 
 
 Rutile is found embedded in granite and other similar rocks, 
 and particularly in the quartz veins which traverse them ; its 
 
138 
 
 ANTASE — NIGRINE. 
 
 slender prisms penetrating the crystals in all directions : speci- 
 mens of rock crystal enclosing parallel fibres of this ore have, 
 when polished, a beautiful appearance, and have been sold 
 under the designation of Venus' Hair. 
 
 Fine specimens are obtained from many parts of the Alps, 
 from Spain, Norway, and North America. In Brazil and Cey- 
 lon, rolled fragments are found in the sand with the sapphires 
 and zircons. 
 
 Brookite has the same colour as rutile, but appears to crys- 
 tallize in oblique rhombic prisms or tables : it has been found 
 in Dauphine, and in the rock crystal of Snowdon, where it was 
 first observed. 
 
 2. Anatase (Octahedrite). This also is an oxyde of tita- 
 nium. It is found only in small crystals, which are acute square 
 octahedrons, of a dark violet colour, or nearly black ; translu- 
 cent, and extremely brilliant. It is scarcely so hard as rutile. 
 Dauphine and the Pyrenees afford good specimens of anatase, 
 intermixed with chlorite and adularia. 
 
 Titanates. 
 
 1. Nigrine (Iserine; Menaccanite ; Titaniferous iron sand). 
 This is a combination of iron with titanic acid, which occurs in 
 the form of black grains or sand. In Cornwall it was found in 
 the Valley of Menaccan, whence the name Menaccanite , and in 
 this substance the metal titanium was first discovered. It is 
 met with in the beds of streams in many countries, and disse- 
 minated in various serpentine rocks, and others of igneous 
 origin, sometimes in minute octahedral crystals. 
 
 Ilmenite , which occurs in somewhat larger masses in the 
 Urals near Minsk, is thought to be the same substance. 
 
 Crichtonite is another rare variety, from the Alps. 
 
 Pyrochlore, containing cerium and uranium, and Polymignite, 
 containing yttria and zirconia, combined with the oxyde of 
 titanium, are rare substances, embedded in the zircon syenite of 
 Norway. 
 
 2. Sphene (Siliceo-titanate of lime ; Spinthere; Ligurite). 
 
TANTALITE TUNGSTEN. 
 
 139 
 
 The transparent crystals of this mineral are often of a bright 
 yellow-green colour, and so brilliant that they might well pass 
 for some kind of gem : the opaque ones are dark reddish 
 brown, and, at first sight, not unlike zircons : they are derived, 
 however, from a very oblique rhombic prism, often presenting 
 numerous modifications which are difficult to distinguish. The 
 name is from sphen , the Greek for a wedge, in reference to 
 their form. Many localities in the Alps afford good speci- 
 mens : particularly, fissures in the granite and other rocks. 
 
 Family II. — Tantalides. 
 
 The few minerals in which tantalum is combined, are very 
 rare : they have been found very sparingly in the granitic 
 rocks near Fahlun in Sweden ; the tantalite also in Connecticut, 
 and baierine in Bavaria. 
 
 Tantalite (Columbite). A black substance with scarcely 
 any metallic lustre, about as hard as felspar, which occurs in 
 small masses and imperfect prismatic crystals. The metal 
 tantalum was discovered in an American specimen, and at first 
 received the name of Columbium : it was found to consist of 
 83 per cent, of the oxyde of this metal, with 17 of the oxydes 
 of iron and manganese : it sometimes contains some oxyde of 
 tin. 
 
 Baierine contains a larger proportion of iron, and crystallizes 
 in rectangular prisms. 
 
 Yttrotantalite , or Yttrocolumbite , is chiefly a tantalate of 
 yttria ; of a greenish or brownish black, and when powdered, 
 grey ; becoming yellow before the blowpipe, and after some 
 time, white ; less hard than the preceding. 
 
 Family III. — Tungstides. 
 
 The metal Tungsten or Scheelium (so named from the 
 chemist, Scheele, its discoverer) exists only as an oxyde, 
 either alone or forming tungstates. 
 
 Tungstic Ochre, or tungstic acid, is a bright yellow powder 
 
140 
 
 TUNGSTATES MOLYBDIDES. 
 
 which is found sometimes on the surface of Wolfram, or filling 
 small cavities. Insoluble, and producing with the salt of 
 phosphorus a blue glass ; thus differing in chemical characters 
 from any similar mineral. 
 
 Tungstates. 
 
 1. Wolfram (Tungstate of Iron and Manganese). A dark 
 brown mineral with semi-metallic lustre, affording distinct and 
 brilliant cleavages parallel to a right-rhomboidal prism. It 
 has a good deal of resemblance to bronzite and to uncrystallized 
 blende ; but its high specific gravity, 7*3, distinguishes it from 
 both. 
 
 It is common in many of the Cornish mines, and other 
 metalliferous districts ; but is of no use, except to afford the 
 tungstic acid, which is prepared for laboratories, and of which 
 it contains about 78 per cent. 
 
 2. Tungstate of Lime (Scheelite) crystallizes in square 
 octahedrons, both obtuse and acute, often modified by addi- 
 tional planes : translucent, and generally white. Specific 
 gravity 6. It occurs in some tin mines, but rarely in Corn- 
 wall ; and in Connecticut, with bismuth. 
 
 3. Tungstate of Lead is a scarce mineral, of a greenish 
 colour, which has been found in the tin mines of Bohemia. 
 
 \ 
 
 Family IV. — Molybdides. 
 
 Molybdic Ochre (Oxyde of Molybdenum) occurs as a 
 yellow powder thinly covering the sulphuret of this metal ; 
 melted with the salt of phosphorus, it produces immediately a 
 green glass. 
 
 Molybdate of Lead crystallizes in square octahedrons, or 
 very short prisms of 4 or 6 sides, of a dull yellow colour, and 
 translucent, which contain 64 per cent, of oxyde of lead. Its 
 chief locality is the Bleiberg (lead mountain), in Carinthia, 
 which affords great variety and fine specimens of the ores of 
 lead. 
 
CHROMIC IRON PITCHBLENDE. 
 
 141 
 
 Family V. — Chromides. 
 
 Chrome is not found in the metallic state : its oxvde is a 
 green ochry substance which is generally intermixed with 
 siliceous minerals ; sometimes in felspathic or talcose rocks ; or 
 combined with other oxydes. 
 
 1. Chromic Iron is a black ore, with but little metallic 
 
 lustre ; massive, and sometimes crystallized in octahedrons : 
 occasionally it is attractable by the magnet : specific gravity 
 4*4, hardness 5*5. * 
 
 This ore has been for some years sought after, to obtain 
 from it the chromic acid, for the preparation of the beautiful 
 chrome-yellow used in painting and dying. It has been found 
 in serpentine in the Shetland Isles, in Styria, the department 
 of Var in France, and other localities ; and very abundantly in 
 Maryland and other parts of the United States. 
 
 Distinguished from magnetic iron by less lustre, and by 
 affording a bright green glass with borax. 
 
 2. Chromate of Lead (Crocoi’se ; Red Lead ore). This 
 is the same substance as the chrome-yellow artificially pre- 
 pared. When crystallized, its colour is of a deep red-orange, 
 and, when powdered, orange-yellow ; the crystals, which are 
 semi-transparent, are oblique rhombic prisms, the base nearly 
 square. They are generally small and slender, and occur with 
 galena, and sometimes pyromorphite, at Beresof, in Siberia ; 
 it has been found more recently, also, at Congonhas do Campo, 
 in Brazil. 
 
 Vauquelinite is a chromate of lead, with 10 per cent, of 
 oxyde of copper, which has been found with the above in green 
 acicular crystals. 
 
 Family VI. — Uranides. 
 
 Besides the phosphate which has been described, uranium 
 occurs as an oxyde, alone, or combined with water. 
 
 1. Pitchblende (Oxydulated Uranium). This is a black 
 or brownish black substance with semi-metallic lustre, scarcely 
 
142 
 
 TJRAN OCHRE — PYROLUSITE. 
 
 so hard as felspar : it is infusible alone, but gives a green 
 colour to the flame. It is found in some veins of silver ore 
 in Saxony and Bohemia, also in Cornwall, but it is a rare mineral. 
 
 2. Uran Ochre occurs as a powder, of a light yellow 
 colour, which becomes orange when gently heated, and gives off 
 water when calcined. The oxyde of uranium has been applied 
 to painting on porcelain, to produce a fine orange colour. 
 
 Family VII. — Manganides. 
 
 The ores of manganese are not found in great abundance, 
 though the metal itself is one of the most widely distributed in 
 nature. As an oxyde or a carbonate, it is combined in many 
 iron ores, and exists in many earthy minerals, particularly 
 mica, of which it is often the colouring matter. 
 
 The native oxydes, of which there are several species, are 
 extensively employed in some manufacturing processes : par- 
 ticularly in the production of chlorine, so essential in bleach- 
 ing : and in glass-making, to destroy the green tinge which it 
 would often otherwise have. Melted with borax they produce 
 an amethyst-coloured glass. 
 
 Oxydes of Manganese. 
 
 1. Pyrolusite (Peroxyde of Manganese). It occurs in 
 groups of small brilliant crystals, like cut steel ; or in long 
 prisms, generally of eight sides, which have a good deal of 
 resemblance to those of grey sulphuret of antimony, but darker 
 in colour ; sometimes forming botryoidal masses with a fibrous 
 structure ; also, compact or granular, with numerous small 
 cavities, which are lined or filled with a blackish powder that 
 soils the fingers strongly, and is the same substance in an 
 earthy form. 
 
 The specific gravity of pyrolusite is 4*8 to 5 ; hardness, 
 rather above calcspar. 
 
 2. Manganite (Hydrous Oxyde of Manganese; Acerdese). 
 This ore differs from the preceding in containing 10 per cent, 
 of water united with the oxydized metal. 
 
PSILOMELANE. 
 
 143 
 
 Its appearance is very similar to that of pyrolusite, but the 
 lustre is less metallic and the colour darker. When crushed, 
 the powder is brown, while that of pyrolusite is black. It is 
 also harder than pyrolusite. 
 
 Wad is the same substance, of an earthy texture, some- 
 times appearing compact when broken : it often occurs in 
 singular dendritic and stalactitic forms, with a smooth surface, 
 but no lustre. 
 
 If this substance be mixed with linseed oil, and kneaded into 
 a dough, the mass will inflame spontaneously. 
 
 All these varieties, as well as the pyrolusite, are obtained in 
 large quantity at Upton Pyne, in Devonshire ; also, in Aber- 
 deenshire, the Pyrenees, and many other parts of Europe. 
 
 Both species are easily distinguished by the blowpipe, from 
 ores of similar appearance. 
 
 3. Psilomelane (Barytiferous Oxvde of Manganese). 
 Another hydrous oxyde which contains from 4 to 16 per cent, 
 of the earth baryta . It does not crystallize, has a bluish-black 
 colour, and when heated with glass of borax produces a violent 
 effervescence. 
 
 It occurs with the above-named ores, principally in the 
 neighbourhood of Macon in Burgundy. 
 
 Braunite and Hausmannite are rare species, crystallizing in 
 square octahedrons of a brownish-black colour, and semi- 
 metallic. 
 
 Marceline is an oxyde containing 15 or more per cent, of 
 silica, which is found abundantly in the valley of St. Marcel in 
 Piedmont, enclosing several interesting substances embedded 
 in it. 
 
 Of all these species, the pyrolusite is the most advantageous, 
 being the most highly oxydized, and free from any other sub- 
 stance, except accidental impurities. The oxygen gas em- 
 ployed in chemical experiments may be obtained from it, by 
 exposing it to heat in a retort ; and when powdered and mixed 
 with muriatic acid, chlorine is given off, which is perceptible 
 by its strong pungent odour. 
 
144 
 
 NATIVE IRON. 
 
 Family VIII. — Siderides. 
 
 Genus I. 
 
 1. Native Iron. Metallic iron is found in very small 
 quantity beneath the surface of the earth : it occurs in small 
 laminae and thin veins among iron ores ; and in small particles 
 in some lavas, both ancient and modern. 
 
 There are, however, many large masses of metallic iron 
 scattered over the earth’s surface, which are known to be of 
 meteoric origin, the period and circumstances of their fall 
 having been recorded, sometimes with great precision. They 
 are perfectly metallic, attractable by the magnet, and malle- 
 able ; and are all found to contain from 1 to 10 per cent, of 
 nickel, and sometimes a very small quantity of chrome or 
 cobalt. 
 
 There are many other metallic masses of whose descent 
 from the atmosphere we have no account, but they are found 
 to consist of a similar alloy ; and, judging from this, and the 
 similarity of their insulated situation, it is impossible not to 
 conclude that they have had the same origin. 
 
 A mass of iron weighing 71 lb., which fell with a smaller 
 fragment, on the explosion of a meteor, in Croatia, in 1751, is 
 to be seen in the Imperial Cabinet of Vienna ; and at the town 
 of Ellbogen in Bohemia, a mass of iron weighing 200 lb. is 
 preserved, which was seen to fall from the air. 
 
 The great mass of iron near Jenissek, in Siberia, which con- 
 tains grains of chrysolite embedded in it, is supposed to weigh 
 1 600 lb. : another, on the banks of the River Plata, is calculated 
 to weigh about 100,000 lb. ; and there are many others of all 
 sizes in different countries. 
 
 * 
 
 Oxydes of Iron. 
 
 1. Peroxyde of Iron (Specular Iron or Iron Glance; Red 
 Haematite ; Red Ironstone) . The crystallized varieties of this 
 ore have a dark steel-grey colour, and a splendent metallic 
 lustre ; and the surface is often tarnished like tempered steel : 
 when scratched or pulverized, however, the powder is dark 
 
HAEMATITE. 
 
 145 
 
 cherry-red, and thin fragments, viewed in a strong light, appear 
 of the same colour. The crystals are acute rhombohedrons, 
 generally with complex modifications ; some are thin hexago- 
 nal tables with oblique edges. The most brilliant specimens 
 come from the Isle of Elba, where mines of this ore have been 
 worked above 2000 years. Some specimens are attractable by 
 the magnet, but this is not a constant character. 
 
 Micaceous iron is the same substance in thin scales : in this 
 form it is scattered through some quartzose rocks, having the 
 appearance of plumbago : in this situation it occurs in Brazil 
 and Coromandel. 
 
 In the British Museum is a specimen of specular iron, in 
 hexagonal plates, in which a topaz is embedded. 
 
 Red Hcematite is always opaque, seldom with any metallic 
 lustre, of a blood-red colour, inclining to steel-grey. It occurs 
 in large nodules and stalactitic forms, with a fine radiated 
 structure : the fibres are sometimes above a foot in length. 
 
 Red ironstone is compact or somewhat granular, and often 
 very pure. 
 
 Red ochre and red chalk (reddle) have an earthy and some- 
 what unctuous texture ; they generally contain a good deal of 
 clay. 
 
 Clay ironstone. An abundant ore, consisting of the red 
 oxyde mixed with earthy substances, chiefly clay and siliceous 
 matters : it is generally dark red or brown, and sometimes 
 very hard. This must not be confounded with the impure 
 carbonate of iron which is also called clay ironstone, and will 
 effervesce in warm nitric acid. 
 
 The red iron ores are abundant in some parts of England, 
 particularly at Ulveustone, in Lancashire, where an immense 
 vein affords all the varieties, accompanied by calcspar : also in 
 Lanarkshire. 
 
 Pieces of hematite are much used in the potteries and other 
 manufactories, as burnishers; and a great deal of red chalk is 
 sawn up into crayons. 
 
 2. Brown Iron Ore (Hydrous Oxyde of Iron ; Hydrate 
 
 H 
 
146 
 
 BOG ORE — IRON ORE. 
 
 of Iron ; Limonite ; Morass Ore ; Yellow Ochre). This ore is 
 of a dark coffee-brown colour, except in the earthy varieties* 
 but when powdered, is yellow : it is softer and more brittle 
 than the red iron ore, and not so heavy. When pure, it con- 
 sists of 85*3 of peroxyde of iron and 14’ 7 of water: but it 
 often contains a little of the oxyde of manganese and silica. 
 
 Brown hcematite resembles the red haematite in its fibrous 
 structure ; but has a silky lustre, and the colour is sometimes 
 varied by bands of a lighter tint near the surface. 
 
 Brown ironstone is compact, sometimes intermixed with clav. 
 
 Bog ore and morass ore are of loose, unequal, friable texture, 
 and occur in low swampy grounds. There is not much of this 
 sort in Great Britain, except at the foot of the Cheviot Hills, 
 though in other parts of Europe it is abundant, and in France 
 is extensively smelted. 
 
 Pea iron ore is the same substance occurring in small globu- 
 lar masses compressed together : in the Jura mountains there 
 are extensive beds of it : these grains, when broken, appear to 
 consist of concentric layers. 
 
 All these varieties are much used in the iron works of France 
 and Prussia ; but until lately, those which occur in England 
 have been neglected, in consequence of the abundance of 
 richer ores. 
 
 Yellow ochre , which is used in various kinds of painting, is 
 sometimes a very pure hydrate of iron ; but the best kind for 
 these purposes contains a good deal of alumina combined with 
 it. There is a large bed of it near Oxford, which is of a very 
 good quality. 
 
 Umber , another pigment, contains a large proportion of the 
 hydrous oxyde of manganese. 
 
 Genus II. Ferrates. 
 
 1. Magnetic Iron Ore (Loadstone; Oxydulous Iron). 
 This ore has a dark iron-grey colour and metallic lustre, and 
 its hardness and specific gravity are nearly the same as of spe- 
 cular iron ore : massive varieties of these two ores resemble 
 
FRANKLINITE NATIVE COPPER. 
 
 147 
 
 each other considerably; but they may be distinguished by 
 pulverizing them : the powder of the specular iron is red ; that 
 of the magnetic iron, black. 
 
 It is always strongly attracted by the magnet, a circumstance 
 which sometimes occurs with the specular ore ; but those spe- 
 cimens which exhibit polarity are themselves natural magnets 
 or loadstones. 
 
 Magnetic iron is scarce in this country, being found only in 
 small crystals, octahedral or dodecahedral (figs. 5, 9, 10), dis- 
 seminated in serpentine and in some schistose rocks : but in 
 Norway and Sweden it forms immense beds many yards in 
 thickness, and even constitutes mountains, as at Taberg and 
 Dannemora ; and at Gellivara in Lapland. It occurs in many 
 other countries, particularly the United States, but not in such 
 extensive masses. 
 
 2. Franklinite is a combination of oxyde of iron with the 
 oxydes of manganese and zinc, which is found at Franklin, in 
 New J ersey. It crystallizes in octahedrons, and has very much 
 the appearance of magnetic iron, but somewhat less metallic, 
 and the streak is reddish brown. 
 
 CoBALTIDES. 
 
 3. Black Oxyde of Cobalt (Cobalt Ochre). A black 
 earthy substance which occurs in several places, both in Europe 
 and America, usually on the surface of other ores of cobalt, 
 and of arsenic, but seldom pure. The ore from Missouri, 
 of which a good deal is now exported to England, for the pur- 
 pose of being converted into smalt, contains 40 per cent, of 
 the oxydes of cobalt, with oxydes of nickel, manganese, iron, 
 and copper. 
 
 Family IX. — Cuprides. 
 
 Native Copper. Like most of the native metals, it crys- 
 tallizes in the octahedral system ; but perfect crystals arc 
 seldom met with. It occurs sometimes in very large masses, 
 but most frequently, in branching and leaf-like forms, scattered 
 
 h 2 
 
148 
 
 RUBY COPPER. 
 
 among the veinstone, or penetrating it : and the surface of 
 these ramifications is often thinly coated with green carbonate 
 of copper, or tarnished of a brownish colour. 
 
 In general it is very nearly pure copper, and has the colour, 
 hardness, and malleability of the refined metal, as we are ac- 
 customed to see it : sometimes it contains a minute proportion 
 of silver. 
 
 Siberia and Cornwall have for ages afforded abundance 
 of native copper, and some of the finest cabinet specimens ; 
 but Brazil and the southern shore of Lake Superior have pro- 
 duced by far the largest masses of metal. A block weighing 
 3704 lbs. was taken from the last-mentioned spot and conveyed 
 to Washington : but many larger ones are said to have been 
 obtained from the same locality. In some parts of this district, 
 the copper is penetrated by threads of pure silver, and grains 
 of the same metal are scattered through it ; a circumstance 
 which has never been observed elsewhere. 
 
 Its softness and ready solubility in every kind of acid, and in 
 ammonia, distinguish copper from the few metallic minerals 
 which at all resemble it. 
 
 Copper is one of the metals that has been known and worked 
 from the earliest period : alloyed with tin its hardness is much 
 increased ; and this alloy formed the various kinds of bronze of 
 which armour, weapons, knives, and other tools were manufac- 
 tured by the former inhabitants of both the old and the new 
 continent. Axes and knives from the tombs of the ancient 
 Peruvians and Mexicans, chisels found in the quarries of Egypt, 
 and Roman and Gaulish swords of great antiquity, have been 
 analysed, and found to contain from 75 to 96 per cent, of 
 copper alloyed with tin. 
 
 OxYDES. 
 
 Ruby Copper (Red Oxyde of Copper; Zigueline). This 
 substance is of a fine crimson colour, sometimes almost black, 
 with a vitreous lustre, varying from semi-transparent to nearly 
 opaque. It crystallizes in octahedrons and dodecahedrons. 
 
NATIVE GOLD. 
 
 149 
 
 sometimes presenting numerous modifications (figs. 4, 5, 9, 
 10, are the most common) : it is brittle, and about as hard as 
 fluorspar, with a specific gravity of 5*6. Detached crystals of 
 a bright colour are very much like spinel rubies ; but the dif- 
 ference of their hardness is a sufficient distinction. It is often 
 intermixed with native copper, but seldom with the other ores 
 of this metal. 
 
 At Chessy, large and perfect pseudomorphous crystals of 
 malachite are found, having the forms of ruby copper. 
 
 Tile ore is a variety which is intermixed with oxyde of 
 iron and other impurities, and forms thin flattisli masses some- 
 thing like dark coloured tiles. 
 
 Black oxyde of copper, which is more oxydated than the pre- 
 ceding species, occurs in the form of a fine black powder, or in 
 small masses of an earthy texture, with some other copper ores. 
 Both this and ruby copper are easily reduced on charcoal to 
 metallic copper. 
 
 Family X. — Aurides. 
 
 Gold is found only in the native or metallic state ; for, 
 though it is alloyed with silver and with tellurium, it is never 
 mineralized by sulphur, oxygen, chlorine^ &c., which, in com- 
 bining with other metals, destroy their metallic character. 
 
 1. Native Gold is often nearly pure ; but it is almost con- 
 stantly alloyed with some proportion of silver, which varies from 
 a very small fraction to 72 per cent. When the quantity of 
 silver is but small, it does not differ in appearance from the 
 gold of commerce : it has the same colour, hardness, and mal- 
 leability, but is less heavy, the specific gravity ranging from 
 12*6 to 14*7 ; this variation depends partly on the amount of 
 silver which it contains : the specific gravity of gold when 
 purified is 19*25. 
 
 Gold crystallizes in cubes and octahedrons, and other forms 
 belonging to the same series. Some of the gold sand of South 
 America consists chiefly of brilliant crystallized grains ; but 
 well-formed crystals of even moderate size are extremely 
 
150 
 
 GOLD. 
 
 scarce : it is more commonly disseminated in small irregular 
 lumps or grains, in veins of quartz or calcspar, accompanying 
 other ores : for it does not, like copper pyrites and cinnabar, 
 fill the veins in which it occurs ; nor even constitute, like 
 native silver, the principal part of their metalliferous contents ; 
 but is scattered through them in minute particles ; or spread 
 out here and there into thin leaves ; or forms, in their cavities, 
 crystallized tufts. 
 
 In Hungary and in some parts of Mexico, gold occurs with 
 the sulphurets of silver : in the Sierra Cocaes of Brazil, beds 
 of granular quartz and micaceous specular iron include a great 
 quantity of native gold in the form of spangles. 
 
 Gold was discovered some years since in lead veins in Meri- 
 onethshire, in sufficient quantity to render the working of it 
 tolerably profitable : it is there sprinkled in fine particles over 
 quartz, or mixed with iron pyrites and decomposing blende. 
 In the Hartz it is found chiefly among decomposing iron 
 pyrites. 
 
 Gold, however, is far more abundant in the sand of rivers, 
 and in alluvial tracts, than in any other situations. Most of 
 the gold of South America, and which for many years was the 
 source of the greater part of the gold circulating and manu- 
 factured in Europe, is obtained from washings in alluvial* 
 grounds. At Choco, along with the gold, platinum, hyacinths, 
 and rutile occur ; and often the trunks of petrified trees : in 
 other localities, diamonds and gold are found together. 
 
 In California, where the late discovery of gold has excited 
 such extraordinary interest, both from the extent of country 
 over which it is scattered, and the unusual size of the pepites 
 (as they are called) in which it occurs, the soil is alluvial, 
 and diamonds are said to have been met with in several spots. 
 A great quantity exists there in small grains and spangles ; the 
 
 * Alluvial is a term used to designate the deposits of loose gravel, sand, 
 and mud, which in many regions are spread over all other strata, chiefly 
 in low grounds, and appear as if carried thither by a stream or flood. 
 The word is derived from alluvio , an inundation. 
 
ELECTRUM. 
 
 151 
 
 large pepites are either of solid metal, or quartz intermixed 
 with gold, and in general strongly coloured by hydrous oxyde 
 of iron. The gold mines of the Urals are situated in alluvial 
 soil, and it is observed that the richest spots are generally 
 those which are the most ferruginous. These mines are said 
 to have been, for some years past, the most productive in the 
 world.* 
 
 The native gold of Africa is in the form of dust intermixed 
 sometimes with larger grains. That country, together with 
 Spain, furnished a great part of the gold possessed by the an- 
 cients : the mines of Gallicia, according to Diodorus Sicu- 
 lus, were worked by the Phoenicians, and afterwards by the 
 Romans. 
 
 Macedonia, Thrace, and the Isle of Thasos, near that coast, 
 also afforded them gold. 
 
 The river Pactolus, celebrated for its golden sands, was said 
 to have been a chief source of the wealth of Croesus, but they 
 have long ceased to be productive. 
 
 Borneo, Sumatra, and many other islands of the Indian Ar- 
 chipelago, as well as Cochin China and Siam, possess produc- 
 tive gold mines. 
 
 In the time of Queen Elizabeth, extensive gold-washings 
 were carried on in the mining district of Leadhills, Scotland : 
 and in the course of a few summers, the quantity collected 
 there, amounted to £100,000. In Wicklow, also, gold was 
 for a short time obtained from a small alluvial tract : and par- 
 ticles of gold occur sometimes in the Cornish stream works. 
 
 2. Electrum is a name applied to a native alloy of 64 parts of 
 gold with 36 of silver. Pliny says that “ all gold contains more 
 or less silver combined with it, and that when the latter amounts 
 to a fifth part of the weight it is called electrum. 9 * When the 
 proportion of silver is large, the alloy has a brassy colour. It 
 is met with generally in veins , in Siberia, Hungary, and Tran- 
 sylvania, but not often in sand or grains. 
 
 * The whole of the Russian mines yielded, in 1842, 42,000 lbs. troy, of 
 which half was from Siberia. 
 
152 
 
 NATIVE PLATINUM. 
 
 Gold is insoluble in every acid except aqua regia (a mixture 
 of nitric and hydrochloric acids), and neither becomes oxydized 
 nor tarnished by exposure to the air. Its extreme malleability, 
 in addition to these properties, renders it a most economical as 
 well as beautiful ornamental material, notwithstanding its high 
 value. It amalgamates readily with mercury, for which reason 
 this metal is used in some places with great advantage for 
 separating gold from the gangue or earthy matter with which it 
 is intermixed. 
 
 Family XI. — Platinides. 
 
 Native Platinum (Platina). This metal, which is the 
 heaviest known substance, is found only in the metallic 
 state, generally alloyed with a small quantity of palladium , iri- 
 dium y osmium , rhodium , or iron : sometimes it is combined with 
 two or three of these metals. It has a pale lead-grey colour, 
 and is found in grains, which are generally very small, rarely 
 as large as a pea. In this state its specific gravity is about 17, 
 but when purified it is 19*5, or rather higher than that of 
 gold.* 
 
 Platinum is a most indestructible substance ; being infusible 
 at a heat which liquifies gold, and unaffected by every acid 
 except the aqua regia ; it is, therefore, of great value as a ma- 
 terial for crucibles and other chemical apparatus. It is also 
 extremely malleable, and so ductile that it has been drawn into 
 wire less than the ten -thousandth of an inch in diameter. 
 
 Platinum was discovered about a hundred years since, in the 
 sands of Barbacoa and Choto, in South America : it was after- 
 wards found in the gold district of Brazil, whence a consider- 
 able quantity was obtained annually. But in 1824 it was 
 discovered on the western side of the Ural Mountains ; and the 
 mines of that district have for several years produced a far 
 greater quantity than all the American localities, and the most 
 
 * Platinum, which has been rendered more dense by hammering, has a 
 sp. gr. from 21 to 23. 
 
PALLADIUM IRIDOSMINE. 
 
 153 
 
 remarkable specimens in point of size and weight : one of these, 
 in the DemidofF Cabinet, weighs 21 lbs. troy; another, 11^. 
 
 Family XII.— Palladides. 
 
 Palladium. Among the grains of Platinum are generally 
 intermixed very small ones of a lighter colour, and sometimes 
 a radiated texture, which have a specific gravity of 11*3 or 
 11*8. These are Palladium: the grains have usually a flat 
 shape, and are soluble in heated nitric acid. 
 
 Palladium has been advantageously used in small slips, to 
 inlay parts of astronomical instruments, wdiere fine graduated 
 lines are cut, being nearly as white as silver, and not liable to 
 tarnish or become oxydated. In the Mint at Paris, there is a 
 highly polished cup of this metal. 
 
 Family XIII. — Osmides. 
 
 Iridosmine (Native Iridium). An alloy of Osmium with 
 Iridium, which occurs in small grains in some of the localities 
 of Platinum. Their specific gravity is above 19, and they are 
 insoluble alone, even in aqua regia. 
 
 The metal iridium received its name from iris, the rainbow, 
 because its different solutions exhibit all the colours of the 
 rainbow. 
 
 n o 
 
154 
 
 ROCKS. 
 
 ON ROCKS OR MINERAL AGGREGATES. 
 
 By James D. Dana, A.M. 
 
 General Nature of Rocks. — The rocks of the globe are min- 
 eral, and consist either of a single mineral in a massive state, 
 or of intimate combinations of different minerals. Limestone, 
 when pure, is a single mineral ; it is the species calcite or car- 
 bonate of lime. Common granite is a compound or aggregate 
 of three minerals — quartz, feldspar, and mica. Sandstones may 
 consist of grains of quartz alone, like the sands of many sea- 
 coasts, being such a rock as these sands would make if agglu- 
 tinated ; it is common to find along with the quartz, grains of 
 feldspar, and sometimes mica. Clay Slates consist of quartz 
 and feldspar or clay, with sometimes mica, all so finely commi- 
 nuted that often the grains cannot be observed. Conglome- 
 rates or pudding stones, may be aggregates of pebbles of any 
 kind : of granite pebbles, of quartz pebbles, of limestone peb- 
 bles, or of mixture of different kinds, cemented together by 
 some cementing material, such as silica, oxyde of iron, or car- 
 bonate of lime. 
 
 Texture or structure of Rocks. — Rocks differ also in texture. 
 In some, as granite, or syenite, the texture is crystalline : that 
 is, the grains are more or less angular, and show faces of 
 cleavage ; the aggregation was the result of a cotemporaneous 
 crystallization of the several ingredients. Common statuary 
 or white building marble consists of angular grains, and is 
 crystalline in the same manner. But a pudding-stone is evi- 
 dently not a result of crystallization ; it consists only of adhering 
 pebbles of other rocks with a cementing material which is often 
 not apparent. Sandstones also are an agglutination of grains 
 of sand, — just such rocks as would be made from ordinary sand 
 by compacting it together; and clay slates are often just what 
 
ROCKS. 
 
 155 
 
 would result from solidifying a bed of clay. There are there- 
 fore crystalline and uncrystalline rocks. It should be remem- 
 bered, however, that in each kind of rock the grains themselves 
 are crystalline, as all solid matter becomes solid by crystal- 
 lization. But the former kind is a crystalline aggregation of 
 grains, the latter a mechanical aggregation. 
 
 In crystalline rocks it is not always possible to distinguish 
 the grains, as they may be so minute, or the rock so compact, 
 that they are not visible. Much of the crystalline rock called 
 basalt is thus compact. 
 
 Positions , or modes of occurrence, of Rocks. — A great part of 
 the rocks of the earth’s surface constitutes extensive beds or 
 layers, lying one above the other, and varying in thickness 
 from a fraction of an inch to many scores of yards. There are 
 compact limestones, -beds of sandstone, and shales or clay 
 slates, in many and very various alternations. In some regions, 
 certain of these rocks, or certain parts of the series, may extend 
 over large areas or underlie a whole country, while others are 
 wholly wanting or present only in thin beds. The irregularities 
 in their geographical arrangement and ih the order of super- 
 position are very numerous, and it is one object of geology to 
 discover order amid the apparent want of system. Thus in 
 Pennsylvania, over a considerable part of the state, there are 
 sandstones, shales, and limestones, connected with beds of coal. 
 In New York there are other sandstones, shales, and lime- 
 stones, without coal ; and the geologist ascertains at once, by 
 his investigation, that no coal can be found in New York. 
 These rocks contain each its own peculiar organic remains, and 
 these are one source of the confident decision of the geologist. 
 The stratified rocks bear evidence in every part — in their regular 
 layers, their worn sand or pebbles, and their fossils — that they 
 are the result of gradual accumulations beneath water, marine 
 or fresh, or on the shores of seas, lakes, or rivers. 
 
 Besides the stratified rocks alluded to, there are others which, 
 like the ejections from a volcano, or an igneous vent, form 
 beds, or break through other strata and fill fissures often many 
 
156 
 
 ROCKS. 
 
 miles in length. The rock filling such fissures, is called a 
 dike. Such are the trap dikes of New England and else- 
 where; they are fissures filled by trap. Porphyry dikes, and 
 many of the veins in rocks, are of the same kind. Similar 
 rocks may also occur as extensive layers ; for the lavas of a 
 single volcanic eruption are sometimes continuous for forty 
 miles. They may appear underlying a wide region of country, 
 like granite. 
 
 The stratified rocks, or such as consist of material in regular 
 layers, are of two kinds. The worn grains of which they are 
 made are sometimes distinct, and the remains of shells farther 
 indicate that they are the result of gradual accumulation. But 
 others, or even certain parts of beds that elsewhere contain 
 these indications, have a crystalline texture. A limestone bed 
 may be compact in one part, and granular or crystalline, like 
 statuary marble, in another. Here is an effect of heat on a 
 portion of the bed ; heat, which has acted since the rock was 
 deposited. Other rocks, such as mica slate, gneiss, and pro- 
 bably some granites, have thus been crystallized. 
 
 In these few general remarks on the structure of the globe, 
 we have distinguished the following general facts : 
 
 1. The great variety of alternations of sandstone, conglo- 
 merates, clay shale, and limestones. 
 
 2. The existence of igneous rocks in beds and intersecting 
 dikes or veins. 
 
 3. The mechanical structure of sandstone, conglomerate, 
 and shales. 
 
 4. The crystalline character of igneous rocks. 
 
 5. The crystalline character of many stratified or sedi- 
 mentary rocks, arising from the action of heat upon the beds of 
 rock themselves, after they were first formed. 
 
 We follow this comprehensive survey of the arrangement 
 and general nature of rocks, with descriptions of the more 
 prominent varieties and their applications in the arts.* 
 
 * One of the most important uses of stone is for architectural purposes. 
 The character of the material depends not only upon its durability, but 
 
GRANITE. 
 
 157 
 
 GRANITE. SYENITE. 
 
 Granite consists of the three minerals, quartz, feldspar, and 
 mica. It has a crystalline granular structure, and usually a 
 greyish-white, grey, or flesh-red colour, the shade varying 
 with the colour of the constituent minerals. When it contains 
 hornblende in place of mica, it is called syenite ; hornblende 
 resembles mica in these rocks, but the laminae separate much 
 less easily and are brittle. 
 
 Granite is said to be micaceous , feldspathic y or quartzose, ac- 
 cording as the mica, feldspar, or quartz predominates. 
 
 It is called porphyritic granite, when the feldspar is in large 
 crystals, and appears over a worn surface like thickly scattered 
 white blotches, often rectangular in shape. 
 
 Graphic granite has an appearance of small oriental cha- 
 
 also its contraction or expansion from changes of temperature. This 
 latter cause occasions fractures or the opening of seams, and produces in 
 cold climates serious injuries to structures. The following table, by Mr. 
 A. J. Adie, gives the rate of expansion in length for different materials, 
 for a change of temperature of 180° F. — Proc, Roy. Soc. Edinb., i. 95, 1835. 
 
 Granite, 
 
 •0008968— • 
 
 Sicilian white marble, 
 
 •00110411 
 
 Carrara marble, 
 
 •0006539 
 
 Black marble, from Galway, Ireland, 
 
 •00044519 
 
 Sandstone, (Craigleith quarry, Scotland,) 
 
 •0011743 
 
 Slate, Penryhn quarry, Wales, 
 
 •0010376 
 
 Greenstone, 
 
 •0008089 
 
 Best Brick, 
 
 •0005502 
 
 Fire brick, 
 
 •0004928 
 
 Cast iron, 
 
 •00114676 — 
 
 Rod of wedgewood ware, 
 
 •00045294 
 
 The experiments of W. H. C. Bartlett, Lieut. U. S. Engineers, led to 
 the following results. — Amer. J . Sci., xxii. 136, 1832. 
 
 For 1° F. 
 
 Granite, -000004825 
 
 Marble, -000005668 
 
 Sandstone, -000009532 
 
 Hammered copper, *000009440 
 
 For 180° F. 
 
 •00086904 
 
 •00102024 
 
 •00171596 
 
 •00169920 
 
158 
 
 GRANITE. 
 
 racters over the surface, owing to the angular arrangement of 
 the quartz in the feldspar, or of the feldspar in the quartz. 
 
 When the mica of the granite is wanting, it is then a 
 granular mixture of feldspar and quartz, called granulite or 
 leptynite. 
 
 When the feldspar is replaced by albite, it is called albite 
 granite. The albite is usually white, but otherwise resembles 
 feldspar. 
 
 Granite is the usual rock for veins of tin ore. It contains 
 also workable veins of pyritous, vitreous, and grey copper ore, 
 of galena or lead ore, of zinc blende, of specular and magnetic 
 iron ore, besides ores of antimony, cobalt, nickel, uranium, 
 arsenic, titanium, bismuth, tungsten, and silver, with rarely a 
 trace of mercury. The rare cerium and yttria minerals are 
 found in granite, and most frequently in albitic granite. It 
 also contains emerald, topaz, corundum, zircon, fluor spar, 
 garnet, tourmaline, pyroxene, hornblende, epidote, and many 
 other species. 
 
 Granite is one of the most valuable materials for building. 
 The rock selected for this purpose should be fine and even in 
 texture, as the coarser varieties are less durable; it should 
 especially be pure from pyrites or any ore of iron, which on 
 exposure to the weather will rust and destroy, as well as de- 
 face, the stone. The only certain evidence of durability must 
 be learned from examining the rock in its native beds ; for 
 some handsome granites which have every appearance of dur- 
 ability, decompose rapidly from some cause not fully under- 
 stood. The more feldspathic are less enduring than the quartz- 
 ose, and the syenitic (or hornblendic) variety, more durable 
 than proper granite itself. The rock, after removal from the 
 quarry, hardens somewhat, and is less easily worked than when 
 first quarried out. 
 
 Massachusetts is properly the granite state of the union. 
 New Hampshire and Maine also afford a good material. The 
 Quincy quarries in Massachusetts, south of Boston, have for 
 many years been celebrated. Besides this locality, there are 
 
GNEISS. 
 
 159 
 
 others in the eastern part of this state, between cape Ann and 
 Salem, in Gloucester, at Fall River, in Troy, in Danvers ; also 
 south, between Quincy and Rhode Island, where it is wrought 
 in many places, as well as in Rhode Island, even to Providence. 
 The so-called Chelmsford granite comes from Westford and 
 Tyngsborough, beyond Lowell ; and an excellent variety is ob- 
 tained at Pelham, a short distance north in New Hampshire. 
 Masses 60 feet in length are obtained at several of the quarries. 
 They are worked into columns for buildings, many fine ex- 
 amples of which are common in Boston, New York, and other 
 cities. 
 
 Good granite is also quarried in Waterford, Greenwich, and 
 elsewhere, in Connecticut. 
 
 The granite is detached in blocks by drilling a series of 
 holes, one every few inches, to a depth of three inches, and 
 then driving in wedges of iron between steel cheeks. In this 
 manner masses of any size are split out. There is a choice of 
 direction, as the granite has certain directions of easiest frac- 
 ture. Masses are often got out in long narrow strips, a foot 
 wide, for fence posts. The granite in a rough state brings 12 
 to 15 cents, the superficial foot; ordinary hewn granite 20 to 
 40 cents, the foot ; worked into columns, 50 cents, to 1 dollar 
 the foot, according to the size. 
 
 Granite is also used for paving, in small rectangular blocks 
 neatly fitted together, as in London and in some parts of New 
 York and other cities. The feldspathic granite is of great 
 value in the manufacture of porcelain, for which purpose it is 
 therefore extensively employed. 
 
 Granite was much used by the ancients, especially the 
 Egyptians, where are obelisks that have stood the weather for 
 3000 years. 
 
 GNEISS. 
 
 Gneiss has the same constitution as granite, but the mica is 
 more in layers, and the rock has therefore a stratified appear- 
 ance. It generally breaks out in slabs a few inches to a foot 
 thick. It is hence much used both as a building material and 
 
160 
 
 MICA SLATE — TALCOSE SLATE. 
 
 for flagging walks. The quarries in the vicinity of Haddam, 
 Conn., on the Connecticut river, are very extensively opened, 
 and a large amount of stone is annually taken out and exported 
 to the Atlantic cities, even as far as New Orleans. There are 
 also quarries at Lebanon and other places, in Connecticut ; at 
 Wilbraham, Millbury, Monson, and many other places, in 
 Massachusetts. 
 
 MICA SLATE. 
 
 Mica slate has the constitution of gneiss, but is thin, slaty, 
 and breaks with a glistening or shining surface, owing to the 
 large proportion of mica, upon which its foliated structure de- 
 pends. Grey or silvery grey is a common colour. 
 
 The thin even slabs of the more compact varieties of mica 
 slate are much used for flagging, and for door and hearth 
 stones ; also for lining furnaces. The finer arenaceous varieties 
 make good scythe stones. 
 
 It is quarried extensively of fine quality, in large even slabs, 
 at Bolton in Connecticut ; also in the range passing through 
 Goshen and Chesterfield, Mass. It is worked into whetstones 
 in Enfield, Norwich, and Bellingham, Mass., and extensively 
 at Woonsocket Hill, Smithfield, R. I. The south part of 
 Chester, Vt., affords a slate like that of Bolton. Mica slate 
 is used at Salisbury, Conn., for the inner wall of the iron 
 furnace. 
 
 Hornblende slate resembles mica slate, but has not as glisten- 
 ing a lustre, and seldom breaks into as thin slabs. It is more 
 tough than mica slate, and is an excellent material for 
 flagging. 
 
 TALCOSE SLATE. TALCOSE ROCK. 
 
 Talcose slate resembles mica slate, but has a more greasy 
 feel, owing to its containing talc instead of mica. It is usually 
 light grey or dark greyish -brown. It breaks into thin slabs, 
 but is generally rather brittle, yet it often makes good fire- 
 stones. 
 
 A talcose slate in Stockbridge, Vt., is worked for scythe 
 stones and hones, and is of excellent quality for this purpose. 
 
TALCOSE ROCK — STEATITE. 
 
 161 
 
 Talcose rock is a kind of quartzose granite, containing more 
 or less talc, and often quite compact. It is usually very much 
 intersected by veins of white quartz. Much of it contains 
 chlorite (an olive-green mineral) in place of talc, here and 
 there disseminated : and there is a chlorite slate , of a dark 
 green colour, similar in general characters to talcose slate. 
 Talcose rock passes into a flinty quartz rock. 
 
 The talcose rocks are to a great extent the gold rocks of the 
 world, especially the quartzose veins, as mentioned under Gold. 
 It contains the topaz of Brazil, and also euclase, and many 
 other minerals. 
 
 STEATITE, OR SOAPSTONE. 
 
 Steatite is a soft stone, easily cut by the knife and greasy in 
 its feel. Its colour is usually greyish-green ; but when smoothed 
 and varnished it becomes dark olive-green. It occurs in beds, 
 associated generally with talcose slate. 
 
 Owing to the facility with which soapstone is worked, and 
 its refractory nature, it is cut into slabs for fire-stones and 
 other purposes, and the powder, finely prepared, is em- 
 ployed for diminishing friction, and for mixing with blacklead 
 in the manufacture of crucibles. It is also used, as observed 
 by Dr. C.T. Jackson, for the sizing rollers in cotton factories, 
 one of which is 4\ feet long and 5 to 6 inches in diameter. 
 The most valuable quarries in Massachusetts are at Middlefield, 
 Windsor, Blandford, Andover, and Chester; in Vermont, at 
 Windham and Grafton ; in New Hampshire, at Francestown, 
 and Oxford ; in Orange county. North Carolina. The Frances- 
 town soapstone sells at Boston at from 36 to 42 dollars the 
 ton, or from 3 to 3^ dollars the cubic foot. 
 
 Steatite often contains disseminated crystals of magnesian 
 carbonate of lime (dolomite,) and brown spar; also crystals 
 of pyrites and actinolite. 
 
 Potstone is a compact steatite. Rensselaerite is another 
 compact variety, found in Jefferson and St. Lawrence counties, 
 N. Y., and used for inkstands. 
 
162 
 
 SERPENTINE TRAP — BASALT. 
 
 SERPENTINE. 
 
 This dark green rock is usually associated with talcose 
 rocks, and often also with granular limestones. It has been 
 already described, and its uses alluded to. It often contains 
 disseminated a foliated green variety of hornblende called 
 diallage. A compound rock, consisting of diallage and feld- 
 spar, has been called diallage rock or euphotide . 
 
 TRAP. BASALT. 
 
 Trap is a dark greenish or brownish-black rock, heavy and 
 tough. Specific gravity 2*8 — 3*2. It has sometimes a granular 
 crystalline structure, and at other times it is very compact 
 without apparent grains. It is an intimate mixture of feldspar 
 and hornblende. It is often called greenstone ; and when con- 
 sisting of albite and hornblende, it is called diorite. 
 
 Amygdaloid (from the Latin amygdalum , an almond,) is a 
 trap containing small almond-shaped cavities, which are filled 
 with some mineral ; usually a zeolite, quartz, or chlorite. 
 
 Porphyritic trap is a trap containing, like porphyritic granite, 
 disseminated crystals of feldspar. 
 
 Basalt is a rock resembling trap, but consisting of augite 
 and feldspar. It varies in colour from greyish to black. In 
 the lighter coloured, which are sometimes denominated grey- 
 stone, feldspar predominates ; and in the darker, iron or a 
 ferruginous augite. It often contains chrysolite (or olivine) in 
 small grains of a bottle-glass appearance. Magnetic or titanic 
 iron are also frequently present in the rock. When feldspar 
 crystals are coarsely disseminated, it is called porphyritic basalt ; 
 and when containing minerals in small nodules, it is amygda- 
 loidal basalt ; when consisting of labradorite and augite, it is 
 called dolerite. 
 
 Wacke or toadstone is an earthy basalt, or a sedimentary 
 rock of trap or basaltic material. 
 
 Both trap and basalt occur in columnar forms, as at the 
 Giant's Causeway and other similar places. 
 
 Trap and basalt are excellent materials for macadamizing 
 
PORPHYRY — CLINKSTONE TRACHYTE. 
 
 163 
 
 roads, on account of their toughness. Trap is also used for 
 buildings. It breaks into irregular angular blocks, and is em- 
 ployed in this condition. For a Gothic building it is well 
 fitted, on account of an appearance of age which it has. 
 
 PORPHYRY. CLINKSTONE. TRACHYTE. 
 
 Porphyry consists mainly of compact feldspar, with dis- 
 seminated crystals of feldspar. Red or brownish-red and 
 green, are common colours ; but grey and black are met with. 
 The feldspar crystals are from a very small size to half or 
 three quarters of an inch in length, and have a much lighter 
 shade of colour than the base, or are quite white. It breaks 
 with a smooth surface and conchoidal fracture. The specific 
 gravity and other characters of the rock are the same nearly as 
 for the mineral feldspar ; the hardness is usually a little higher 
 than in that mineral. 
 
 Porphyry receives a fine polish, and has been used for 
 columns, vases, mortars, and other purposes. Green porphyry 
 is the oriental verd antique of the ancients, and was held in 
 high esteem. The red porphyry of Egypt is also a beautiful 
 rock. It has a clear brownish-red colour, and is sprinkled 
 with small spots of white feldspar. 
 
 Clinkstone or Phonolite is a greyish-blue rock, consisting, 
 like porphyry, mainly of feldspar. It passes into grey basalt, 
 and is distinguished by its less specific gravity. It rings like 
 iron when struck with a hammer, and hence its name. 
 
 Trachyte is another feldspathic rock, distinguished by break- 
 ing with a rough surface, and showing less compactness than 
 clinkstone. It sometimes contains crystals of hornblende, 
 mica, or some glassy feldspar mineral. It occurs in volcanic 
 regions. 
 
 LAVA. OBSIDIAN. PUMICE. 
 
 The term lava is applied to any rock material which has 
 flowed in igneous fusion from a volcano. Basalt is one kind 
 of lava ; and when containing cellules, it is called basaltic lava . 
 Trachyte is also a lava. There are thus both feldspathic and 
 
164 
 
 CLAY SLATE. 
 
 basaltic lavas. The feldspathic are light-coloured, and of low 
 specific gravity (not exceeding 2*8) ; the basaltic vary from 
 greyish-blue to black, and are above 2*8 in specific gravity. 
 The general term basaltic sometimes includes doleritic lava, 
 which is closely allied. Chrysolite is often present in basaltic 
 lavas ; and they are not unfrequently porphyritic, or contain 
 disseminated crystals of feldspar. 
 
 The light cellular ejections of a volcano are called scoria or 
 pumice . 
 
 Pumice is feldspathic in constitution ; it is very porous, and 
 the fine pores lying in one direction make the rock appear to 
 be fibrous. It is so light as to float on water. It is much 
 used for polishing wood, ivory, marble, metal, glass, &c., and 
 also parchment and skins. The principal localities are the 
 islands of Lipari, Ponza, Ischia, and Vulcano, in the Mediter- 
 ranean, between Sicily and Naples. Both scoria and pumice 
 are properly the scum of a volcano. 
 
 Volcanic ashes are the light cinders or minute particles of 
 rock, ejected from a volcano in the course of an eruption. 
 
 Obsidian is a volcanic glass. It resembles ordinary glass. 
 Black and smoky tints are the common colours. In Mexico, 
 it was formerly used both for mirrors, knives, and razors. 
 Pitchstone is less perfectly glassy in its character, and has a 
 pitch-like lustre ; otherwise it resembles obsidian. Pearlstone 
 has a greyish colour and pearly luster. Spherulite is a kind of 
 pearlstone, occurring in small globules in massive pearlstone. 
 Marekanite is a pearl-grey translucent obsidian from Marekan 
 in Kamschatka. 
 
 ARGILLACEOUS SHALE, OR CLAY SLATE. ARGILLITE. 
 
 Slate is an argillaceous rock, breaking into thin laminae ; 
 shale , a similar rock, with the same structure usually less per- 
 fect and often more brittle ; schist includes the same varieties 
 of rock, but is extended also to those of a much coarser lami- 
 nated structure. The ordinary clay slate has the same consti- 
 tution as mica slate ; but the material is so fine that the in- 
 
ROOFING SLATE. 
 
 165 
 
 gredients cannot be distinguished. The two pass into one 
 another insensibly. The colours are very various, and always 
 dull or but slightly glistening. 
 
 Roofing slate is a fine grained argillaceous variety, commonly 
 of a dark dull blue or bluish-black colour, or somewhat 
 purplish. To be a good material for roofing, it should split 
 easily into even slates, and admit of being pierced for nails 
 without fracturing. Moreover, it should not be absorbent of 
 water, either by the surface or edges, which may be tested by 
 weighing after immersion for a while in water. It should also 
 be pure from pyrites and everything that can undergo decom- 
 position on exposure. 
 
 Roofing slates occur in England, in Cornwall, Devon, Cum- 
 berland, and Westmoreland. 
 
 In the United States, a good material is obtained in Maine, 
 at Barnard, Piscataquies, Kennebec, Bingham, and elsewhere ; 
 also in Massachusetts, in Worcester county, in Boylston, Lan- 
 caster, Harvard, Shirley, and Peperell ; in Vermont, at Guil- 
 ford, Brattleborough, Fairhaven, and Dummerston ; in Hoosic, 
 New York ; on Bush creek, and near Unionville, Maryland ; 
 at the Cove of Wachitta, Arkansas. At Rutland, Vt., is a 
 manufactory of slate pencils from a greenish slate. 
 
 These slate rocks are also used for gravestones ; and we 
 cannot go through New England cemeteries without frequent 
 regret, that a material which is sure to fall to pieces in a few 
 years should have been selected for such records. 
 
 Drawing slate is a finer and more compact variety, of bluish 
 and purplish shades of colour. The best slates come from 
 Spain, Italy, and France. A good quality is quarried in Maine 
 and Vermont. 
 
 Novaculite , hone-slate , or whet-stone , is a fine grained slate, 
 containing considerable quartz, though the grains of this 
 mineral are not perceptible. It occurs of light and dark 
 shades of colour, and compact texture. It is found in North 
 Carolina, seven miles west of Chapel Hill, and elsewhere ; 
 in Lincoln and Oglethorpe counties, Georgia ; on Bush creek, 
 
166 
 
 QUARTZ ROCK. 
 
 and near Unionville, Maryland; and at the Cove of Wachitta, 
 Arkansas. 
 
 Argillite is a general term given to argillaceous or clay 
 slate rocks. Many shales or argillites crumble easily, and are 
 unfit for any purpose in the arts, except to furnish a clayey 
 soil. 
 
 Alum shale is any slaty rock which contains decomposing 
 pyrites, and thus will afford alum or sulphate of alumina on 
 lixiviation. 
 
 Bituminous shale is a dark-coloured slaty rock containing 
 some bitumen, and giving off a bituminous odour. 
 
 Plumbaginous schist is a clay slate containing plumbago or 
 graphite, and leaving traces like black lead. 
 
 The Pipestone of the North American Indians, was in part a 
 red clay stone or compacted clay from the Coteau de Prairies. 
 It has been named catlinite . A similar material, now ac- 
 cumulating, occurs on the north shore of Lake Superior, at 
 Nepigon bay. Another variety of pipestone is a dark greyish 
 compact argillite ; it is used by the Indians of the northwest 
 coast of ilmerica. 
 
 Agalmatolite is a soft mineral, impressible by the nail, and 
 waxy in lustre when polished, presenting greyish and greenish 
 colours and other shades. Gr.= 2*8 — 2*9. It has a greasy 
 feel. It consists of silica 55*0, alumina 30*0, potash 7*0, 
 water 3 to 5 per cent., with a trace of oxyde of iron. It is 
 carved into images, and is hence called figure-stone. 
 
 QUARTZ ROCK. 
 
 Quartz rock is a compact rock consisting of quartz, and often 
 appearing granular. Its colours are light grey, reddish, or 
 dull bluish ; also sometimes brown. 
 
 When the granular quartz contains a little mica, it often 
 breaks in slabs like gneiss or mica slate. The itacolumite of 
 Brazil, with which gold and topaz are associated, is a mica- 
 . ceous granular quartz rock of this kind. 
 
 Flexible sandstone is an allied rock of finer texture. Gran- 
 
BUHRSTONE. 
 
 167 
 
 ular quartz graduates into the proper sandstones, which are 
 treated of for convenience on a following page. The two rocks 
 are properly parts of one series. 
 
 Granular quartz is one of the most refractory of rocks. It 
 is consequently used extensively for hearthstones, for the lining 
 of furnaces, and for lime kilns. At Stafford, Conn., a loose 
 grained micaceous quartz rock is highly valued for furnaces ; it 
 sells at the quarry for about £3 8s. per ton.* 
 
 Granular quartz is also used for flagging, and a fine quarry 
 is opened in Washington, near Pittsfield, Mass.; it also occurs 
 of good quality at Tyringham and Lee, Mass. In the shape 
 of cobble stones, it is a common paving material. 
 
 A highly important use of this rock is in the manufacture of 
 glass and sandpaper, and for sawing marble. In many places 
 it occurs crumbled to a fine sand, and is highly convenient for 
 these purposes. In Cheshire, Berkshire county. Mass., and in 
 Lanesboro , > Mass., it occurs of superior quality, and in great 
 abundance. It is also in demand for the manufacture of glass 
 and pottery. In Unity, N. H., a granular quartz is ground 
 for sandpaper and for polishing-powder ; the latter is a good 
 material for many purposes. 
 
 A fine variety of granular quartz is a material much valued 
 for whet-stones. 
 
 BUHRSTONE. 
 
 Buhr stone is a quartz rock containing cellules. It is as hard 
 and firm as quartz crystal, and owes its peculiar value to this 
 quality and the cellules, which give it a very rough surface. 
 In the best stones for wheat or corn the cavities about equal 
 in space the solid part. The finest quality comes from France, 
 in the basin of Paris, and some adjoining districts. 
 
 The stones are cut into wedge-shaped parallelopipeds called 
 panes, which are bound together by iron hoops into large mill- 
 stones. The Paris buhrstone is from the tertiary formation, 
 and is therefore of much more recent origin than the quartz 
 rock above described. 
 
 * Rep. on Connecticut, by C. U. Shepard, p. 78. 
 
168 
 
 SANDSTONES. 
 
 Buhrstone of good quality is abundant in Ohio, and others 
 of the western states. It is associated therewith proper sand- 
 stones. 
 
 The quartz rock of Washington, near Pittsfield, Mass., is in 
 some parts cellular, and makes good millstones. 
 
 A buhrstone occurs in Georgia, about 40 miles from the sea, 
 near the Carolina line ; also in Arkansas, near the Cove of 
 Wachitta. 
 
 SANDSTONES. GRIT ROCKS. CONGLOMERATES. 
 
 Sandstones consist of small grains, aggregated into a com- 
 pact rock. They have a harsh feel, and every dull shade of 
 colour from white, through yellow, red, and brown, to black. 
 Many sandstones are very compact and hard, while others 
 break or rub to pieces in the fingers. They usually consist of 
 siliceous sand ; but grains of feldspar are often present. In 
 many compact sandstones there is much clay, and the rock is 
 then an argillaceous sandstone. 
 
 Sandstones are of all geological ages, from the lower Silu- 
 rian to the most recent period. The older rocks are in general 
 the most firm and compact. The “ old red ” sandstone is a 
 sandstone below the coal in age ; while the so-called “ new 
 red ” is more recent than the coal. But these terms, beyond 
 this particular point, are of somewhat indefinite application. 
 The sandstone of the Connecticut valley is called the new red 
 sandstone. 
 
 Grit rock. When the sandstone is very hard and harsh, 
 and contains occasional siliceous pebbles, it is called a grit 
 rock, or millstone grit. 
 
 Conglomerates . Conglomerates consist mostly of pebbles 
 compacted together. They are called pudding stone when the 
 pebbles are rounded, and breccia when they are angular. 
 They may consist of pebbles of any kinds, as of granite, quartz, 
 limestone, &c., and they are named accordingly granitic , 
 quartzose, calcareous , conglomerates. 
 
 The use of sandstone as a building material is well known. 
 For this purpose it should be free, like granite, from pyrites or 
 
SANDSTONES. 
 
 169 
 
 iron sand, as these rust and disfigure the structure. It should 
 be firm in texture, and not liable to peel off on exposure. Some 
 sandstones, especially certain argillaceous varieties, which ap- 
 pear well in the quarry, when exposed for a season where 
 they will be left to dry, gradually fall to pieces. The 
 same rock answers well for structures beneath water, that 
 is worth nothing for buildings. Other sandstones which are 
 so soft as to be easily cut from their bed without blasting, 
 harden on exposure, (owing to the hardening of silica in the 
 contained moisture,) and are quite durable. These are qualities 
 which must be tested before the stone is used. Moreover, 
 it should be considered that in frosty climates a weak absorb- 
 ent stone is liable to be destroyed in a comparatively short 
 time, while in a climate like that of Peru even sunburnt bricks 
 will last for centuries. 
 
 Dr. Ure observes, that “such was the care of the ancients 
 to provide strong and durable materials for their public edifices, 
 that but for the desolating hands of modern barbarians, in 
 peace and in war, most of the temples and other public monu- 
 ments of Greece and Rome would have remained perfect at the 
 present day, uninjured by the elements during 2000 years. 
 The contrast in this respect of the works of modern architects, 
 especially in Great Britain, [much more true of the United 
 States,] is very humiliating to those who boast so loudly of 
 social advancement ; for there is’ scarcely a public building of 
 recent date which will be in existence a thousand years hence.” 
 Many splendid structures are monuments (not endless) of folly 
 in this respect. He observes, also, that the stone intended for a 
 durable edifice ought to be tested as to its durability by im- 
 mersion in a saturated solution of sulphate of soda, and expo- 
 sure to the air for some days : the crystallization within the 
 stone will cause the same disintegration that would result in 
 time from frost. 
 
 The dark red sandstone ( freestone ) of New Jersey and Con- 
 necticut, when of fine gritty texture and compact, is generally 
 an excellent building material. Trinity Church in New York 
 
 i 
 
170 
 
 SANDSTONES. 
 
 is built of the stone from Belville, New Jersey. At Chatham, 
 on the Connecticut, is a large quarry, which supplies great 
 quantities of stone to the cities of the coast ; and there are 
 numerous others in the Connecticut valley, both in Connecticut 
 and Massachusetts. A variety in North Haven, at the east 
 end of Mount Carmel, has been spoken of as excellent for or- 
 namental architecture. That of Longmeadow and Wilbraham, 
 in Massachusetts, is a very fine and beautiful variety and is 
 much used. A freestone occurs also at the mouth of Seneca 
 creek, Maryland, convenient for transportation by the Chesa- 
 peak and Ohio canal ; white and coloured sandstones occur also 
 at Sugarloaf Mountain, Maryland. 
 
 The sandstone of the Capitol at Washington is from the 
 Potomac ; it is a poor material. 
 
 Sandstones that split into thin layers form excellent flag- 
 ging stones, and are in common use. 
 
 Hard, gritty sandstones and the grit rocks are used for the 
 hearths of furnaces, on account of their resistance to heat. 
 They are also much used for millstones, and when of firm tex- 
 ture make a good substitute for the buhrstone. 
 
 The true buhrstone has been described as a cellular siliceous 
 rock, without an apparent granular texture. The buhrstone of 
 Ohio approaches this character ; it is in part a true sandstone 
 containing fossils in some places, and overlying the coal. Much 
 of it contains lime ; and it is possible that the removal of the 
 lime by solution, since its deposition, may have occasioned its 
 cellular character. It has an open cellular structure where 
 quarried for millstones. It occurs in Ohio, in the county of 
 Muskingum, and the counties south and west of south, on the 
 Raccoon river and elsewhere. The manufacture commenced in 
 this region in 1807 ; and in Richland, Elk, and Clinton, and in 
 Hopewell, the manufacture is now carried on extensively. 
 Stones 4 feet in diameter bring ^§r!50. 
 
 The “ green sand” of the cretaceous formation contains 
 grains of silicate of iron and potash, to which it owes its 
 greenish tint. It occurs abundantly in New Jersey as a soft 
 
LIMESTONES. 
 
 171 
 
 rock, and is much used for improving lands ; a value it owes 
 mostly to the alkali it contains. 
 
 Pudding stones and breccias are fitted, in general, only for 
 the coarser uses of stone, as for foundations, hutments of 
 bridges. Occasionally, when of limestone, they make hand- 
 some marbles, as the <f Potomac breccia marble’’ ontheMono- 
 cacey, which forms the columns in the Hall of Representatives 
 of Washington. 
 
 Porphyry conglomerates , basaltic conglomerates , pumiceous 
 conglomerates , consist respectively of pebbles or fragments of 
 porphyry, basalt, pumice. 
 
 Tufa is a sandrock consisting of volcanic material, either 
 cinders or the comminuted lavas. Pozzuolana is a kind of tufa 
 found in the vicinity of Rome, Italy. It consists of silica 34*5, 
 alumina 15, lime 8*8, magnesia 4*7, potash 1*4, soda 4*1, 
 oxydes of iron and titanium 12, water 9*2. Peperino is a 
 coarse sandrock, made up of volcanic cinders or fine fragments 
 of scoria, partially agglutinated. 
 
 LIMESTONES. 
 
 Limestones consist essentially of carbonate of lime, and 
 belong to the species calcite, or otherwise of the carbonates of 
 lime and magnesia. They are distinguished by being easily 
 scratched with a knife, and by effervescing with an acid. They 
 are either compact or granular in texture : the compact break 
 with a smooth surface, often conchoidal ; the granular have a 
 crystalline granular surface, and the fine varieties resemble loaf 
 sugar. 
 
 Granular limestone. The finest and purest white crystalline 
 limestones are used for statuary and the best carving, and are 
 called statuary marble . A variety less fine in texture is em- 
 ployed as a building material. Its colours are white, and 
 clouded of various shades. It often contains scales of mica 
 disseminated, and occasionally other impurities, from which 
 the cloudings arise. 
 
 The finest statuary marble comes from the Italian quarry at 
 
 i 2 
 
172 
 
 LIMESTONES. 
 
 Carrara ; from the Island of Paros, whence the name Parian ; 
 from Athens, Greece ; from Ornofrio, Corsica, of a quality 
 equal to that of Carrara. The Medicean Venus and most of 
 the fine Grecian statues are made of the Parian marble. These 
 quarries, and also those of the Islands of Scio, Samos, and 
 Lesbos, afforded marble for the ancient temples of Greece and 
 Rome. The Parthenon at Athens was constructed of marble 
 from Pentelicus. 
 
 Statuary marble has been obtained in the United States, but 
 not of a quality equal to the foreign. Fine building material is 
 abundant along the Western part of Vermont, and south 
 through Massachusetts to Western Connecticut and Eastern 
 New York. In Berkshire county. Mass., marble is quarried 
 annually to the value of ^200,000 ; the principal quarries are 
 at Sheffield, West Stockbridge, New Ashford, New Marl- 
 borough, Great Barrington, and Lanesborough. The columns 
 of the Girard College are from Sheffield, where blocks 50 feet 
 long are sometimes blasted out; the material of the City Hall, 
 New York, came from West Stockbridge ; that of the Capitol 
 at Albany, from Lanesboro’. At Stoneham is a fine statuary 
 marble ; but it is difficult to obtain large blocks. The variety 
 from Great Barrington is a handsome clouded marble. Some 
 of the West Stockbridge marble is flexible in thin pieces when 
 first taken out. There are Vermont localities at Dorset, Rut- 
 land, Brandon, and Pittsford. In New York extensive quar- 
 ries are opened not far from New York, at Sing Sing ; also at 
 Patterson, Putnam county ; at Dover in Dutchess county, N.Y.; 
 in Connecticut there are marble quarries at New Prestou ; in 
 Maine at Thomaston ; in Rhode Island at Smithfield, a fine 
 statuary; in Maryland, a few miles east of Hagerstown; in 
 Pennsylvania, a fine clouded variety, 20 miles from Philadel- 
 phia. A fine dun-coloured marble is obtained at New Ashford 
 and Sheffield, Mass., and at Pittsford, Vt. 
 
 The granular limestone when coarse usually crumbles easily, 
 and is not a good material for building. But the finer varieties 
 are not exceeded in durability by any other architectural rock. 
 
LIMESTONES. 
 
 173 
 
 not even by granite. The impurities are sometimes so abun- 
 dant as to render it useless. For statuary, it is essential that 
 it should be uniform in tint and without seams or fissures ; the 
 liability of finding cloudings within the large blocks would 
 altogether discourage their use for statuary. 
 
 The common minerals in this rock are tremolite, asbestos, 
 scapolite, chondrodite, pyroxene, apatite, besides sphene, spinel, 
 graphite, idocrase, mica. 
 
 Verde antique marble — verde antico — is a clouded green 
 marble, consisting of a mixture of serpentine and limestone, 
 as already described under Serpentine. It occurs at Milford, 
 near Newhaven, Connecticut, of fine quality ; and also in 
 Essex county, N.Y., at Moria, and near Port Henry on Lake 
 Champlain. A marble of this kind occurs at Genoa and in 
 Tuscany, and is much valued for its beauty. A variety is called 
 polzivera di Genoa and vert d’ Egypt e. 
 
 The Cipolin marbles of Italy are white, or nearly so, with 
 shadings or zones of green talc. The bardiglio is a grey va- 
 riety from Corsica. 
 
 Compact limestone usually breaks out easily into thick slabs, 
 and is a convenient and durable stone for building and all 
 kinds of stone work. It is not possessed of much beauty in 
 the rough state. When polished it constitutes a variety of 
 marbles, according to the colour; the shades are very numerous, 
 from white, cream, and yellow shades, through grey, dove- 
 coloured, slate blue, or brow T n, to black. 
 
 The Nero-antico marble of the Italians is an ancient deep 
 black marble ; the paragone is a modern one, of a fine black 
 colour, from Bergamo ; and panno di morte is another black 
 marble with a few white fossil shells. 
 
 The rosso-antico is deep blood- red, sprinkled with minute 
 white dots. The giallo-antico , or yellow antique marble, is 
 deep yellow with black or yellow rings. A beautiful marble 
 from Sienna, brocatello de Siena , has a yellow colour, with 
 large irregular spots and veins of bluish-red or purplish. The 
 mandelato of the Italians is a light red marble, with yellowish- 
 
174 
 
 LIMESTONES. 
 
 white spots ; it is found at Luggezzana. At Verona, there is a 
 red marble , inclining to yellow, and another with large white 
 spots in a reddish and greenish paste. 
 
 The black marble used in the United States comes mostly 
 from Shoreham, Vt., and other places in that state near Lake 
 Champlain. The Bristol marble of England is a black marble 
 containing a few white shells, and the Kilkenny is another 
 similar. There are several quarries at Isle La Motte. It is 
 quarried also near Plattsburgh and Glenn’s Falls, N.Y. 
 
 The portor is a Genoese marble very highly esteemed. It is 
 deep black, with elegant veinings of yellow. The most beau- 
 tiful comes from Porto- Venese, and under Louis XIV. a great 
 deal of it was worked up for the decoration of Versailles. 
 
 Grey and dove-coloured compact marbles are common 
 through New York and the states West. 
 
 The bird’s-eye marble of Western New York is a compact 
 limestone, with crystalline points scattered through it. 
 
 Ruin marble is a yellowish marble, with brownish shadings 
 or lines arranged so as to represent castles, towers, or cities in 
 ruins. These markings proceed from infiltrated iron. It is 
 an indurated calcareous marl. 
 
 Oolitic marble has usually a greyish tint, and is speckled with 
 rounded dots, looking much like the roe of a fish. 
 
 Shell marble contains scattered fossils, and may be of different 
 colours. It is abundant through the United States. Crinoidal 
 or encrinital marble differs only in the fossils being mostly 
 remains of encrinites, resembling thin disks. Large quarries 
 are opened in Onondaga and Madison counties, N.Y., and the 
 polished slabs are much used. Madreporic marble consists 
 largely of corals, and the surface consists of delicate stars : it 
 is the pietra stellaria of the Italians. It is common in some of 
 the states on the Ohio. Fire marble , or lumachelle , is a dark 
 brown shell marble, having brilliant fire or chatoyant reflections 
 from within. 
 
 Breccia marbles and pudding stone marbles are the polished 
 calcareous breccia or pudding stone. 
 
LIMESTONES. 
 
 175 
 
 Stalagmites and stalactites are frequently polished, and the 
 variety of banded shades is often highly beautiful. The Gibraltar 
 stone , so well known, is of this kind. It comes from a cavern 
 in the Gibraltar rock, where it was deposited from dripping 
 water. It is made into inkstands, letter-holders, and various 
 small articles. 
 
 Wood is often petrified by carbonate of lime, and occasion- 
 ally whole trunks are changed to stone. The specimens show 
 well the grain of the wood, and some are quite handsome 
 when polished. 
 
 Marble is sawn by means of a thin iron plate and sand, either 
 by hand or machinery. In polishing, the slabs are first worn 
 down by the sharpest sand, either by rubbing two slabs toge- 
 ther or by means of a plate of iron. Finer sand is afterwards 
 used, and then a still finer. Next emery is applied of increas- 
 ing fineness by means of a plate of lead ; and finally the last 
 polish is given with tin-putty, rubbed on with coarse linen 
 cloths or baggings, wedged tight into an iron planing tool. 
 More or less water is used throughout the process. 
 
 Quicklime . Limestone when burnt produces quicklime, 
 owing to the expulsion of the carbonic acid by the heat. The 
 purest limestone affords the purest lime (what is called fat 
 lime). But some impurities are no detriment to it for making 
 mortar, unless they are in excess. Hydraulic lime , which is so 
 called because it will set under water, is made from limestone 
 containing some clay, silica, and often magnesia. The French 
 varieties contain 2 or 3 per cent, of magnesia, and 10 to 20 of 
 silica and alumina or clay. The varieties in the United States 
 contain 20 to 40 per cent, of magnesia, and 12 to 30 per cent, 
 of silica and alumina. A variety worked extensively at Ron- 
 dout, N.Y., afforded Prof. Beck carbonic acid 34*20, lime 
 25*50, magnesia 12*35, silica 15*37, alumina 9*13, peroxyde 
 of iron 2*25. Oxyde of iron is rather prejudicial than other- 
 wise. 
 
 In making mortar, the lime is mixed with water and silice- 
 ous sand. The final strength of the mortar depends principally 
 
1 76 
 
 LIMESTONES. 
 
 on the formation of a compound between water, the silica (or 
 sand), and the lime ; of course, therefore, the finer the sand, 
 the more thorough the combination. In hydraulic lime, there 
 are silica and alumina present in a thoroughly disseminated and 
 finely divided state, which is favourable for the combination 
 alluded to ; and to this fact appears to be mainly owing its hy- 
 draulic character. Much less sand is added in making mortar 
 from this lime than from that of ordinary limestone. 
 
 Pozzuolana forms an hydraulic cement when mixed with a 
 little lime and water. Similar cements may be made with 
 tufa, pumice stone, and slate clay, by varying the proportions 
 of lime; these materials consist essentially of silica and alumina 
 or magnesia with alkalies, and often some lime, and therefore 
 produce the same result as with hydraulic limestone. 
 
 In the burning of lime, the most common mode is to erect a 
 square or circular furnace of stone, with a door for managing 
 the fire below. An arched cavity for the fire is first made of 
 large pieces of limestone, and then the furnace is filled with 
 the stone placed loosely so as to admit of the passage of the 
 flame throughout : the carbonic acid is expelled by the heat, 
 and when the fires are out, the lime now in the state of quick- 
 lime, or in other words, pure lime, is taken out. Great 
 economy of fuel is secured by means of what is called a per- 
 petual kiln . The cavity within is best made nearly of the 
 shape of an egg with the narrow end uppermost. The inner 
 walls are of quartz rock, mica slate, or some refractory stone 
 or fire brick, and between the inner and outer there is a layer 
 of cinders or ashes, as in the iron furnace. Below are three 
 or more openings for furnaces which lead into the main cavity, 
 a few feet from the bottom ; and alternate with these are other 
 openings at a lower level for withdrawing the lime. The lime 
 is taken out below and the stone thrown in above, and this 
 may be kept up without intermission as long as the kiln lasts. 
 Beneath the furnaces there are also ash pits. Such a kiln is 
 most convenient for being filled and emptied when situated on 
 a side hill. 
 
SAND — CLAY. 
 
 177 
 
 The localities of limestone in the United States are too 
 common to need enumeration. Hydraulic limestone is also 
 abundant. 
 
 Quicklime is much used for improving lands ; also for clari- 
 fying the juice of the sugar cane and beet root ; for purifying 
 coal gas ; for clearing hides of their hair in tanneries, and for 
 various other purposes. 
 
 SAND. CLAY. 
 
 The loose or soft material of the surface of the earth consists 
 of sand, clay, gravel, or stones, and what we call, in general 
 terms, soil, or earth. These materials are either in layers or 
 irregular beds. Most clay beds, and many of gravel, when 
 cut through vertically, show indications of horizontal layers, a 
 result of deposition, or distribution, by water. 
 
 In geological language, these stratified deposits are often 
 classed with rocks, as they graduate into true rocks, and differ 
 only in the amount of cementing material. 
 
 The ordinary constituents of earth are quartz, feldspar or 
 clay, oxyde of iron, and lime ; but these vary with the source 
 from whence they are derived. When the rock that has 
 afforded the soil is granite, mica slate, or the allied rocks, mica 
 is usually present, as well as feldspar and quartz : so a quartz- 
 ose rock will furnish siliceous gravel ; a magnesian, will give 
 magnesia to the soil ; calcareous, lime ; trap, the ingredients 
 of decomposed feldspar or hornblende. The material will be 
 coarse or gravelly, or fine earthy, according to the nature of 
 the rock, or the condition under which it is worn down, or its 
 subsequent distribution by flowing waters. Besides the pro- 
 minent constituents mentioned, there are small proportions of 
 phosphates, nitrates, chlorides, &c., together with the results of 
 vegetable decomposition ; and these comparatively rare ingre- 
 dients are of great importance to growing vegetation. The 
 pebbles of a soil are commonly siliceous, as this kind resists 
 wear most effectually. 
 
 Sand is usually pulverized quartz, often with some feldspar. 
 Clay is a plastic earth, consisting mainly of alumina one third 
 
178 
 
 SAND — CLAY. 
 
 part, and silica (quartz) two thirds. It owes its plasticity to 
 the alumina, and ceases to be called clay when the proportion 
 of silica is too great for plasticity. It is afforded by the de- 
 composition of feldspar and all argillaceous rocks. Oxyde of 
 iron, carbonate of lime, and magnesia are often present in 
 clays. 
 
 Sand for glass manufacture should be pure silica, free from a 
 taint of iron. This purity is apparent in the clearness of the 
 grains, under a lens, or their white colour. That of Cheshire 
 and Lanesboro , , in Massachusetts, is a beautiful material. 
 
 In the manufacture of glass , the object is to form a transpa- 
 rent fusible compound, and not an opaque infusible one, as in 
 pottery. This result is secured by heating together to fusion, 
 silica (quartz sand or flint powder) and the alkali potash or 
 soda. The ingredients combine and produce a silicate of pot- 
 ash or soda — in other words, glass. 
 
 Besides these ingredients, lime or oxyde of lead are added for 
 glass of different kinds. A small proportion of lime increases 
 the density, hardness, and lustre of glass, producing a specific 
 gravity between 2‘5 and 2*6; while with lead a still denser 
 material is formed — called crystal or flint glass — whose specific 
 gravity is from 3 to 3*6. 
 
 From 7 to 20 parts of lime are added for 100 of silica, and 
 25 to 50 of calcined sulphate or carbonate of soda ; common 
 salt (chloride of sodium) may also be employed. A good 
 colourless glass has been found by analysis to consist of silica 
 76*0, potash 13*6, and lime 10*4 parts, in a hundred. For 
 coarse bottle-glass, wood-ashes and coarse sea-weed soda, 
 called kelp, or else pearlashes, are used along with siliceous 
 sand and broken glass. For a hard glass, the proportion of 
 alkali is small. 
 
 The best English crystal glass analyzed by Berthier, afforded 
 59 parts of silica, 9 of potash, 28 of oxyde of lead, and 1*4 of 
 oxyde of manganese. Crown glass contains, in general, less 
 alkali than crystal glass, and is superior in hardness. The 
 alkali, moreover, in England, is soda instead of potash. Plate 
 
SAND CLAY. 
 
 179 
 
 glass also contains soda, and this soda (the carbonate) is pre- 
 pared with great care. The proportions are 7 parts of sand, 
 1 of quicklime, 2^ of dry carbonate of soda, besides cullet or 
 broken plate. 
 
 The materials are first well pounded and sifted, and mixed 
 into a fine paste ; they are then heated together in pots made 
 of a pure refractory clay, until fusion has taken place and the 
 material has settled. The glass is afterwards worked by blow- 
 ing, or moulded, into the various forms it has in market ; and 
 it is finally annealed — or in other words, is very slowly cooled 
 — to render it tough. A little oxyde of manganese is usually 
 employed to correct the green colour which glass is apt to de- 
 rive from any oxyde of iron present. But if the manganese is 
 in excess, it gives a violet tinge to it. 
 
 The following chemical distribution of glasses has been pro- 
 posed : 
 
 Soluble glass. A simple silicate of potash or soda, or of both 
 of these alkalies. 
 
 Bohemian or crown glass . Silicate of potash and lime. 
 
 Common window and mirror glass. Silicate of soda and lime ; 
 sometimes also of potash. 
 
 Bottle glass. Silicate of soda, lime, alumina, and iron. 
 
 Ordinary crystal glass , Silicate of potash and lead. 
 
 Flint glass. Silicate of potash and lead ; more lead than in 
 the preceding. 
 
 Strass . Silicate of potash and lead — still more lead. 
 
 Enamel . Silicate and stannate, or antimonate of potash or 
 soda and lead. 
 
 Glass was manufactured by the Phoenicians and the later 
 Egyptians. According to Pliny and Strabo, the glass works of 
 Sidon and Alexandria, whence emanated beautiful articles, were 
 famous in their times. The Romans employed glass to some 
 extent in their windows, and remains of this glass are found in 
 Herculaneum. Window glass manufacture was first com- 
 menced in England in 1557. 
 
 Sand for casting is a fine siliceous sand, containing a little 
 
180 
 
 SAND — CLAY. 
 
 clay to make it adhere somewhat and retain the forms into 
 which it may be moulded. It must be quite free from lime. 
 
 Tripoli is a fine grained earthy deposit, having a dry, harsh 
 feel, and a white or greyish colour. It contains 80 per cent, 
 of silica, mostly derived from the casts of animalcules. It is 
 valuable as a polishing material. 
 
 Marl. Marl is a clay containing carbonate of lime. The 
 material is valuable as manure. The term is also improperly 
 applied to any clayey earth used in fertilizing land. The green 
 sand in New Jersey is sometimes called marl. 
 
 Fuller s earth is a white, greyish, or greenish- white earth, 
 having a soapy feel, which was formerly used for removing oil 
 or grease from woollen cloth. It falls to pieces in water, and 
 forms a paste which is not plastic. A variety consists of silica 
 44*0, alumina 23*1, lime 4*1, magnesia 2*0, protoxyde of iron, 
 2*0. Gr. = 2*45. 
 
 Lithomarge is a compact clay of a fine smooth texture, and 
 very sectile. Its colours are white, greyish, bluish- white, 
 reddish- white, or ochre-yellow, with a shining streak. Gr. = 
 2*4 — 2*5. The tuesite of Thomson, a white lithomarge from 
 the banks of the Tweed, is said to make good slate pencils. 
 
 Clay for bricks is the most ordinary kind; it should have 
 slight plasticity wfien moistened, and a fine even character 
 without pebbles. It ordinarily contains some hydrated oxyde 
 of iron, which whep heated turns red by the escape of the 
 water in its composition, which reduces it to the red oxyde of 
 iron, and gives the usual red colour to the brick. It also fre- 
 quently contains lime ; but much lime is injurious, as it 
 renders the brick fusible. A clay is extensively employed 
 at Milwaulde, in Michigan, which contains no iron, and 
 produces a very handsome cream-coloured brick. About 
 9,000,000 of this brick were made at that place in 1847. 
 
 In making bricks , the clay is first well worked by the tread- 
 ing of cattle or by machinery : after this, it is moulded in 
 moulds of the requisite size (9f inches, by 4f and 2f,) and 
 then taken out and laid on the ground. A good workman 
 
SAND CLAY. 
 
 181 
 
 will make by hand 5000 in a day, and the best 10,000. After 
 drying till stiff enough to bear handling, the bricks are trimmed 
 off with a knife when requiring it, and piled up in long walls 
 for farther drying. They are then made into a kiln by piling 
 them in an open manner (so that the flame and heated draft 
 may have passage among them), and leaving places beneath 
 for the fires. The heat is continued forty-eight hours or 
 more. 
 
 The best brick are pressed in moulds. They have a smooth, 
 hard surface. Near Baltimore, Md., bricks are thus made by 
 a machine, worked by a single horse, which wdll mould 30,000 
 bricks in twelve hours ; the bricks are dry enough when first 
 taken from the mould for immediate burning. 
 
 Burnt bricks were not used in England before the eleventh 
 century, when they were employed in the construction of the 
 abbey of St. Alban’s. But they date historically as far back as 
 the city of Babylon. Unburnt bricks have also been used in 
 all ages. Those of Egyptian and Babylonish times were made 
 of worked clay mixed with chopped straw, to prevent it from 
 falling to pieces. The adobies of Peru are large sun-baked 
 bricks or blocks of clay, and in that dry climate they are very 
 durable. 
 
 Clay for Fire-bricks should contain no dime, magnesia, or 
 iron, as its value depends on its being very refractory. There 
 is a large manufactory in the United State^, at Baltimore, from 
 the tertiary clays of» eastern Maryland. In England a slate 
 clay from the coal series is employed. 
 
 Potter s clay and pipe clay are pure plastic clays, free from 
 iron, and consequently burning white. The clay of Milwaukie, 
 from which the cream-coloured bricks are made, is much used 
 also for pottery. 
 
 In the manufacture of coarse pottery , the clay is worked with 
 water and tempered ; and then the required form of a pot or 
 pan is given on a wheel. The ware is dried under cover for a 
 while, and next receives the glaze in a cream-like state. The 
 glaze for the most common ware consists of very finely pul- 
 
182 
 
 SAND — CLAY. 
 
 verized galena, mixed with clay and water. The ware after 
 drying again is next placed in the kiln, which is very gradually 
 heated ; the heat causes the baking of the clay, and drives off 
 the sulphur of the galena, thus producing an oxyde of lead, 
 which forms a kind of glass (or glaze) with the alumina. For 
 a better stone ware, common salt is used, and it is put on after 
 the baking has begun. 
 
 For the finer earthenware, a mixture of red and white lead, 
 feldspar, silica, and flint-glass, is used for a glaze, the propor- 
 tions differing according to the ware. The clay for this ware 
 is mixed with flint powder (ground flints or sand), to render 
 it less liable to contract or break, and it is worked with great 
 care, and through various processes to prepare it for moulding. 
 The ware is usually baked to a biscuit, before the glazing is 
 put on, as in the manufacture of porcelain. 
 
 Kaolin or porcelain clay is derived from the decomposition 
 of feldspar. The foreign kaolin occurs in Saxony ; in France 
 at St. Yrieux-la-Perche, near Limoges ; in Cornwall, England ; 
 also in China and Japan. The kaolin used at the Philadelphia 
 porcelain works comes mostly from the neighbourhood of 
 Wilmington, Delaware. 
 
 The name kaolin is a corruption of the Chinese Kauling, 
 meaning liigh-ridge , the name of a hill near Jauchau Fu, where 
 this material is obtained. 
 
 In the manufacture of porcelain , the kaolin, and also the 
 other ingredients, are first ground up separately to an impal- 
 pable powder. The kaolin is mixed with a certain proportion of 
 feldspar, flint, and lime. The whole are worked up together 
 in water, by mallets and spades, and well kneaded by the hands 
 and sometimes the feet of the workmen. The plastic material 
 is then laid aside in masses of the size of a man’s head, and 
 kept damp till required ; the doughy as it is called, is now 
 ready for the potter’s lathe, (or other means,) by which it is 
 moulded into the various forms of china ware. After mould- 
 ing, they are slowly and thoroughly dried, and then taken to 
 the kiln, for a preliminary baking. They come out in a state 
 
SAND — CLAY. 
 
 183 
 
 of biscuit , and are ready for painting and glazing. The colours 
 are metallic oxydes, which are put on either from a wet copper- 
 plate impression on bibulous paper, or by means of a brush. 
 The former is used for flat surfaces ; the paper is rubbed on 
 carefully to transfer the impression to the porcelain, and is 
 then wet and washed off. It is then carefully heated to 
 evaporate any oil or grease employed in the printing. The 
 glaze is made of a quartzose feldspar ; it is ground to a very 
 fine powder and worked into a paste with water, and a little 
 vinegar. The articles are dipped for an instant into this milky 
 fluid, and as they absorb the water they come out with a deli- 
 cate layer of feldspar in a dry state. They are touched with a 
 brush wherever not well covered. They are then ready to be 
 finally baked in the kiln, for which purpose each vessel is placed 
 in a separate baked clay case or receptacle, called a sagger. 
 In this process the material undergoes a softening, amounting 
 almost to a partial fusion, and thus receives the translucency 
 which distinguishes porcelain from earthen or stone ware. 
 
 The blue colour of common china is produced by means of 
 oxyde of cobalt ; carmine, purple, and violet, by means of chlo- 
 ride of gold ; red of all shades, by oxyde of iron ; yellow, by 
 oxyde of lead, or wdiite oxyde of antimony and sand ; green, 
 by oxyde of copper or carbonate of lead ; brown, by oxyde of 
 iron, manganese, or copper. A steel lustre is produced from 
 chloride of platinum. 
 
 The best Sevres ware is made from 63 to 70 parts of kaolin, 
 15 to 22 of feldspar, nearly 10 of flint, and 5 or 6 of chalk. 
 In China the kaolin is mixed with a quartzose feldspar rock, 
 consisting mainly of quartz, called peh-tun-tsz. 
 
 Soapstone is sometimes used in this manufacture ; and as it 
 substitutes magnesia for a part of the potash, it makes a harder 
 ware ; but it is also more brittle. 
 

 
 
 
 
 
 
 
 
 
 ■ 
 
 
 
 
 . 
 
 . . ' i -■ 
 
 . 
 
 . 
 
 V 
 
 > 
 
 
 
 
INDEX. 
 
 Abrazite, page 57. 
 
 Acid, muriatic, 114. 
 
 sulphuric, 106. 
 
 sulphurous, 106. 
 
 Actinolite, 70. 
 
 Adularia, 49. 
 
 Agalmatolite, 54, 166. 
 Agate, 40. 
 
 Alabandine, 100. 
 
 Alabaster, 100. 
 
 Alalite, 68. 
 
 Albite, 51, 158. 
 
 Allagite, 72. 
 
 Allanite, 63. 
 
 Alum, 106. 
 
 Alumite, 107. 
 
 Alumstone, 113, 166. 
 Amalgam, 133. 
 
 Amber, 80. 
 
 Amianth, 70. 
 
 Amphibole, 69. 
 Amygdaloid, 162. 
 Analcime, 57. 
 
 Anatase, 138. 
 
 Andalusite, 51. 
 
 Anglarite, 123. 
 
 Anglesite, 113. 
 
 Anorthite, 51. 
 Anthophyllite, 67. 
 Anthracite, 78. 
 
 Antimonial silver, 135. 
 Antimony, native, 135. 
 
 sulphuret, 102. 
 
 oxyde, 135. 
 
 Apatite, 120. 
 
 Aplome, 47. 
 
 Apophyllite, 63. 
 Aquamarine, 44. 
 Argillaceous shale, 164. 
 
 Argillite, 164. 
 
 Arragonite, 84. 
 
 Arsenic, native, 124. 
 
 oxyde, 125. 
 
 Arseniate of cobalt, 126. 
 
 copper, 126. 
 
 iron, 127. 
 
 • lead, 126. 
 
 lime, 125. 
 
 nickel, 126. 
 
 Arsenical cobalt, 124. 
 
 antimony, 125. 
 
 bismuth, 125. 
 
 nickel, 125. 
 
 silver, 125. 
 
 • pyrites, 100. 
 
 Asbest, 76. 
 
 Asparagus stone, 121. 
 Asphaltum, 78. 
 Atacamite, 116. 
 
 Augite, 68. 
 
 Automolite, 130. 
 Avanturine, 37. 
 Axestone, 67. 
 
 Axinite, 61. 
 
 Azure copper ore, 88. 
 Azurite, 122. 
 
 Azote, 90. 
 
 Baierine, 139. 
 
 Baikalite, 47. 
 
 Baryta, carbonate, 87. 
 
 sulphate, 108. 
 
 Barytocalcite, 87. 
 
 Basalt, 155, 162, 163. 
 Bellmetal ore, 98. 
 
 Beryl, 44. 
 
 Bismuth, native, 136, 
 
 arsenical, 125. 
 
 K 
 
186 
 
 INDEX 
 
 Bismuth, sulphuret, 102. 
 
 ochre, 137. 
 
 Bitterspar, 84. 
 
 Bitumen, 77. 
 
 Bitumenized wood, 79. 
 
 Bituminous shale, 166. 
 
 Blacklead, 76. 
 
 Black tellurium, 120. 
 
 Blende, 101. 
 
 Blowpipe, 29. 
 
 its effect on oxydes, 33. 
 
 Bloodstone, 40. 
 
 Bluespar, 122. 
 
 Blue vitriol, 112. 
 
 Bog iron ore, 146. 
 
 Bole, 44. 
 
 Bologna spar, 108. 
 
 Boracic acid, 73. 
 
 Borax, 73. 
 
 Botryolite, 73. 
 
 Bournonite, 101. 
 
 Braunite, 143. 
 
 Breccia, 168. 
 
 Brewsterite, 56. 
 
 Brocatella de Siena, 173. 
 Brochantite, 113. 
 
 Bromine, 117. 
 
 Bronzite, 67. 
 
 Brookite, 138. 
 
 Brown coal, 79. 
 
 haematite, 146. 
 
 spar, 85. 
 
 Brucite, 130. 
 
 Buhrstone, 167. 
 
 Byssolite, 70. 
 
 Cacholong, 42. 
 
 Calamine, 72, 86. 
 
 electric, 72. 
 
 Calcedony, 38. 
 
 Calcspar, 81. 
 
 Calcareous tufa, 83. 
 
 Calomel, 115. 
 
 Capolin, 173. 
 
 Carbon, 27, 74, 80. 
 
 Carbonate of baryta, 87. 
 
 copper, 88. 
 
 iron, 85. 
 
 lead, 87. 
 
 lime, 81. 
 
 magnesia, 85. 
 
 manganese, 86. 
 
 soda, 80. 
 
 Carbonate of strontia, 87. 
 
 zinc, 86. 
 
 Carburetted hydrogen, 77. 
 Catlinite, 166. 
 
 Cawk, 109. 
 
 Celestine, 107. 
 
 Cerine, 63. 
 
 Cerite, 63. 
 
 Ceylanite, 130. 
 
 Chabasite, 57. 
 
 Chalcolite, 124. 
 
 Chalk, 65, 83. 
 
 Characters of minerals 
 External, 4. 
 
 Chemical, 29. 
 
 Chiastolite, 51. 
 
 Chlorite, 54, 161. 
 Chloro-carbonate of lead, 116. 
 Chlorophane, 118. 
 
 Chloruret of ammonia, 115. 
 
 copper, 116. 
 
 lead, 116. 
 
 mercury, 115. 
 
 potassium, 115. 
 
 silver, 115. 
 
 sodium, 114. 
 
 Chondrodite, 64. 
 
 Chromate of lead, 141. 
 Chromic ochre, 141. 
 
 iron, 141. 
 
 Chrysoberyl, 45. 
 
 Chrysocolle, 72. 
 
 Chrysolite, 45, 64. 
 Chrysoprase, 40. 
 
 Cimolite, 44. 
 
 Cinnabar, 92. 
 
 Clausthalite, 119. 
 
 Clay, 177. 
 
 iron ore, 86, 145. 
 
 slate, 154, 164. 
 
 Cleavage, 13. 
 
 Cleavelandite, 51. 
 
 Clinkstone, 163. 
 
 Coal, 78. 
 
 Cobalt ochre, 147. 
 
 Cobaltine, 104. 
 
 Cobalt pyrites, 104. 
 
 Coccolite, 69. 
 
 Cologne earth, 79. 
 
 Colophonite, 46. 
 
 Colorados ore, 116. 
 
 Colours of minerals, 20. 
 Columbite, 139. 
 
INDEX 
 
 187 
 
 Condurrite, 127. 
 Conglomerates, 154, 168. 
 Copper, native, 147. 
 
 oxydes, 148. 
 
 pyrites, 97. 
 
 mica, 126. 
 
 Coquimbite, 112. 
 
 Corundum, 128. 
 
 Crichtonite, 138. 
 
 Cryolite, 118. 
 
 Crystalline forms of minerals, 5 
 Cube ore, 127. 
 
 Cube spar, 111. 
 
 Cubicite, 57. 
 
 Cymophane, 45. 
 
 Datholite, 73. 
 
 Diallage, 67, 162. 
 
 Diallagite, 86. 
 
 Diamond, 74. 
 
 spar, 128. 
 
 Diaspore, 129. 
 
 Dichro'ite, 49. 
 
 Diopside, 68. 
 
 Dioptase, 72. 
 
 Disthene, 43. 
 
 Dodecahedrons, 6. 
 
 Dolomite, 84. 
 
 Double refraction, 16. 
 Dysodyle, 80. 
 
 Edelforsite, 63. 
 
 Effervescence, 32. 
 
 Egyptian pebble, 40. 
 
 Elaolite, 52. 
 
 Electrum, 151. 
 
 Elementary substances, 27. 
 Emerald, 44. 
 
 Emery, 128. 
 
 Epidote, 48. 
 
 Epsom salt, 107. 
 
 Euchroite, 127. 
 
 Euclase, 45. 
 
 Eudyalite, 62. 
 
 Eukairite, 119. 
 
 Euphotide, 67, 162. 
 
 Fahlore, 97. 
 
 Fassaite, 68. 
 
 Fatstone, 52. 
 
 Felspar, 49. 
 
 Figurestone, 54, 166. 
 
 Fixed air, 80. 
 
 Flexibility, 23. 
 
 Flexible sandstone, 166. 
 Flint, 39. 
 
 Flinty slate, 40. 
 Floatstone, 37. 
 
 Fluate of alumina, 118. 
 
 cerium, 118. 
 
 lime, 117. 
 
 Fluorine, 117. 
 
 Fluorspar, 117. 
 
 Fossil copal, 80. 
 Franklinite, 147. 
 Freestone, 169. 
 
 French chalk, 65. 
 
 Fullers’ earth, 44, 180. 
 
 Gadolinite, 63. 
 
 Galena, 100. 
 
 Garnet, 46, 54. 
 
 Gehlenite, 48. 
 Giallo-antico, 173. 
 Gieseckite, 52. 
 
 Gibbsite, 129. 
 
 Giobertite, 85. 
 
 Girasol, 41. 
 
 Gismondine, 57. 
 
 Glassy felspar, 51. 
 Glauber salt, 111. 
 Glauberite, 111. 
 
 Gneiss, 159. 
 
 Gold, native, 149. 
 Goniometer, 12. 
 Grammatite, 70. 
 
 Granite, 154, 157. 
 Granulite, 158. 
 
 Graphic gold, 119. 
 Graphite, 76. 
 
 Green earth, 55. 
 
 -vitriol, 112. 
 
 Grenatite, 43. 
 
 Grey antimony, 102. 
 
 copper ore, 97. 
 
 Grit rock, 168. 
 
 Grossular, 46. 
 
 Gurhofian, 85. 
 
 Gypsum, 109. 
 
 Haidingerite, 103. 
 
 Hair pyrites, 102. 
 Halloysite, 44. 
 
 Hardness of minerals, 22. 
 Harmotome, 56. 
 Hatchetine, 80. 
 
188 INDEX. 
 
 Hausmannite, 143. 
 
 Haiiyine, 63. 
 
 Heavyspar, 108. 
 
 Hedenbergite, 69. 
 
 Heliotrope, 40. 
 
 Hepatic cinnabar, 93. 
 
 Hepatite, 109. 
 
 Heulandite, 56. 
 
 Highgate resin, 80. 
 
 Honeslate, 165. 
 
 Hornblende, 67, 69, 160. 
 Hornstone, 39. 
 
 Horn mercury, 115. 
 
 silver, 115. 
 
 Hyalite, 42. 
 
 Hyacinth, 56, 60. 
 
 Hydrate of alumina, 129. 
 
 magnesia, 130. 
 
 Hydraulic lime, 175. 
 
 Hydrochloric acid, 114. 
 
 Hydrogen, 89. 
 
 Hydrous oxyde of iron, 145. 
 
 manganese, 142. 
 
 Hypersthene, 67. 
 
 Icespar, 52. 
 
 Idocrase, 47. 
 
 Ilmenite, 138. 
 
 Ilvaite, 71. 
 
 Indicolite, 49. 
 
 Iodides, 116. 
 
 Iodine, 116. 
 
 Iolite, 49. 
 
 Iridium, 153. 
 
 Iridosmine, 153. 
 
 Iron, native, 144. 
 
 — — glance, 144. 
 
 pyrites, 98. 
 
 spar, 85. 
 
 Iserine, 138. 
 
 Isomorphism, 28. 
 
 Itacolumite, 166. 
 
 Jade, 58, 67. 
 
 Jamesonite, 103. 
 
 Jargoon, 60. 
 
 Jasper, 40. 
 
 Jet, 79. 
 
 Kaolin, 43, 182. 
 
 Kakoxene, 123. 
 
 Kobellite, 110. 
 
 Kollyrite, 44. 
 
 Koupholite, 57. 
 Kupfernickel, 125. 
 
 Kyanite, 43. 
 
 Labradorite, 51. 
 
 Labrador hornblende, 67. 
 Lapis lazuli, 61. 
 
 Laumonite, 57. 
 
 Lava, 163. 
 
 Lead, native, 134. 
 
 oxydes, 134. 
 
 aluminate, 130. 
 
 arseniate, 126. 
 
 r carbonate, 87. 
 
 chloro-carbonate, 116, 
 
 chloruret, 116. 
 
 chromate, 140. 
 
 molybdate, 140. 
 
 phosphate, 123. 
 
 sulphate, 113. 
 
 sulpho-carbonate, 88. 
 
 sulphuret, 100. 
 
 tellururet, 120. 
 
 Lenticular copper ore, 126. 
 Lenzinite, 44. 
 
 Lepidolite, 60. 
 
 Leptynite, 158. 
 
 Leucite, 54. 
 
 Lignite, 79. 
 
 Limestone, 82, 171. 
 Lithomarge, 44, 180. 
 Lydianstone, 40. 
 
 Macled crystals, 11. 
 Magnesian limestone, 84. 
 Magnesite, 66, 85. 
 
 Magnetic iron ore, 157. 
 
 pyrites, 99. 
 
 Magnetism, 26. 
 
 Malachite, 89. 
 
 Mandelate, 174. 
 
 Manganese spar, 72. 
 Manganesian garnet, 47. 
 Manganite, 142. 
 
 Marble, 82, 154, 171, 173. 
 Marceline, 143. 
 
 Marl, 180. 
 
 Marmolite, 66. 
 
 Marekanite, 53, 164. 
 Mascagnine, 112. 
 Meerschaum, 66. 
 
 Meionite, 48. 
 
 Melanite, 47. 
 
INDEX 
 
 189 
 
 Menaccanite, 138. 
 Menilite, 42. 
 
 Mercury, native, 132. 
 
 chloruret, 115. 
 
 sulphuret, 92. 
 
 Mesotype, 55. 
 
 Mica, 59, 160. 
 
 Micaceous iron, 145. 
 Minerals, classification, 34. 
 Mineral charcoal, 78. 
 
 oil, 77. 
 
 waters, 90. 
 
 Mispikel, 100. 
 
 Mochastone, 40. 
 
 Molybdate of lead, 140. 
 Molybdenite, 100. 
 Molybdenum, oxyde, 140. 
 Moonstone, 50. 
 
 Mountain cork, 71. 
 
 leather, 71. 
 
 Muriate of soda, 114. 
 Muriacite, 111. 
 
 Mussite, 68. 
 
 Myargyrite, 95. 
 
 Naphtha, 77. 
 
 Natrolite, 55. 
 
 Natron, 81. 
 
 Needle ore, 102. 
 
 zeolite, 55. 
 
 Nemalite, 85. 
 
 Nepheline, 52. 
 
 Nephrite, 67. 
 
 Nero-antico, 173. 
 
 Nickel, arsenical, 125. 
 
 glance, 102. 
 
 ochre, 125. 
 
 — pyrites, 102. 
 Nigrine, 138. 
 
 Nipoli, 180. 
 
 Nitre, 91. 
 
 Nitrate of lime, 91. 
 
 magnesia, 91. 
 
 potash, 91. 
 
 soda, 91. 
 
 Novaculite, 165. 
 
 Obsidian, 53, 163. 
 Octahedrite, 138. 
 
 Oliven ore, 126. 
 
 Olivine, 64. 
 
 Onyx, 38, 83. 
 
 Oolite, 83. 
 
 Opal, common, 41. 
 
 precious, 41. 
 
 Ophite, 66. 
 
 Oriental stones, 45, 58, 128. 
 Orpiment, 105. 
 
 Orthite, 63. 
 
 Orthose, 49. 
 
 Osmium, 153. 
 
 Oxyde of antimony, 135. 
 
 arsenic, 125. 
 
 bismuth, 137. 
 
 • chrome, 141. 
 
 cobalt, 147. 
 
 copper, 148. 
 
 iron, 145. 
 
 lead, 134. 
 
 manganese, 142. 
 
 molybdenum, 140. 
 
 tin, 131. 
 
 titanium, 137. 
 
 uranium, 141. 
 
 zinc, 136. 
 
 Palladium, 153. 
 
 Paranthine, 48. 
 
 Pargasite, 70. 
 
 Pea iron ore, 146. 
 
 Pearlspar, 85. 
 
 Pearlstone, 53, 164. 
 
 Peastone, 83. 
 
 Peliom, 49. 
 
 Peperino, 171. 
 
 Peridot, 64. 
 
 Petalite, 53. 
 
 Petrifying springs, 83. 
 Phillipsite, 57, 96. 
 Pharmacolite, 125. 
 
 Pholerite, 44. 
 
 Phonolite, 163. 
 
 Phosphate of alumina, 121. 
 
 copper, 123. 
 
 iron, 122. 
 
 lead, 123. 
 
 lime, 120. 
 
 magnesia, 122. 
 
 uranium, 124. 
 
 Phosphorite, 120. 
 
 Photizite, 72. 
 
 Pinite, 52. 
 
 Pipestone, 166. 
 
 Pistacite, 48. 
 
 Pitchblende, 141. 
 
 Pitchstone, 53, 164. 
 
190 
 
 INDEX. 
 
 Plagionite, 104. 
 
 Plaster of Paris, 110. 
 Platinum, 152. 
 
 Pleonaste, 130. 
 
 Plombgomme, 130. 
 Plumbaginous schist, 166. 
 Plumbago, 76. 
 
 Polarization of light, 17. 
 Polybasite, 95. 
 
 Polychroism, 21. 
 
 Polyhallite, 111. 
 
 Polymignite, 138. 
 
 Polzivera di Genoa, 173. 
 Porcelain earth, 43. 
 Porphyry, 163. 
 
 Portor, 174. 
 
 Potstone, 65, 161. 
 Pozzualano, 176. 
 
 Prehnite, 57- 
 Pseudomalachite, 123. 
 Pseudomorphous crystals, 36. 
 Psilomelane, 143. 
 Puddingstone, 154, 168. 
 Pumice, 53, 163. 
 
 Pycnite, 59. 
 
 Pyreneite, 47. 
 
 Pyrgomme, 68. 
 
 Pyrochlore, 138. 
 
 Pyrolusite, 142. 
 Pyromorphite, 123. 
 
 Pyrope, 46. 
 
 Pyrophysalite, 59. 
 
 Pyrorthite, 63. 
 
 Pyroxene, 68. 
 
 Quartz, 35, 166. 
 
 Quicklime, 82, 175. 
 Quicksilver, 132. 
 
 Realgar, 105. 
 
 Red antimony, 135. 
 
 haematite, 144. 
 
 silver ore, 95. 
 
 Rensselaerite, 161. 
 Retinasphalte, 80. 
 
 Rhaetizite, 43. 
 
 Rhodonite, 72. 
 
 Rock crystal, 35. 
 
 salt, 114. 
 
 Rocks, 154. 
 
 Roestone, 83. 
 
 Rose quartz, 37. 
 
 Rosso-antico, 173. 
 
 Rubellite, 60. 
 
 Ruby copper, 148. 
 
 oriental, 128. 
 
 spinel, 129. 
 
 Rutile, 137. 
 
 Sahlite, 68. 
 
 Sal ammoniac, 114. 
 
 — polychrest, 112. 
 
 Saltpetre, 91. 
 
 Sand, 37, 177. 
 
 Sandstone, 37, 154, 166, 168, 
 Sappare, 43. 
 
 Sapphire, 49, 127. 
 
 Sardonyx, 39. 
 
 Satin spar, 82. 
 
 Scapolite, 48. 
 
 Scheelite, 140. 
 
 Schiererite, 80. 
 
 Schillerspar, 67. 
 
 Schist, 164. 
 
 Schorl, 60. 
 
 Scoria, 164. 
 
 Selenite, 109. 
 
 Selenium, 1 19. 
 
 Seleniurets, 119. 
 
 Serpentine, 66, 162. 
 
 Shale, 164. 
 
 Siderose, 85. 
 
 Silicious sinter, 42. 
 Sillimanite, 43. 
 
 Silver glance, 94. 
 
 native, 133. 
 
 Skolesite, 55. 
 
 Skorodite, 127. 
 
 Slates, 154, 160, 164. 
 Smaltine, 124. 
 
 Smaragdite, 67. 
 
 Soapstone, 65, 161. 
 
 Spartalite, 136. 
 
 Spathic iron, 85. 
 
 Specific gravity, 23. 
 
 Specular iron, 144. 
 Spessartine, 47. 
 
 Sphene, 138. 
 
 Spherulite, 53, 164. 
 
 Spinel ruby, 129. 
 
 Spodumen, 52. 
 
 Stalactite, 83. 
 
 Staurotide, 43. 
 
 Steatite, 65, 161. 
 
 Stilbite, 56. 
 
 Stinkstone, 83. 
 
INDEX 
 
 191 
 
 Stream-tin, 131. 
 Stromeyerine, 95. 
 Strontianite, 87. 
 
 Sulphate of alumina, 107. 
 
 ammonia, 112. 
 
 baryta, 108. 
 
 cobalt, 113. 
 
 copper, 112. 
 
 iron, 112. 
 
 lead, 113. 
 
 lime, 109. 
 
 magnesia, 107. 
 
 potash, 112. 
 
 soda, 111. 
 
 ■ - zinc, 113. 
 
 Sulpho-carbonate of lead, 88. 
 Sulphur, 91, 106. 
 
 Sulphuric acid, 106. 
 Sulphuret of arsenic, 105. 
 
 bismuth, 102. 
 
 c — cobalt, 104. 
 
 copper, 95. 
 
 iron, 98. 
 
 lead, 100. 
 
 manganese, 100. 
 
 — mercury, 92. 
 
 silver, 94. 
 
 zinc, 101. 
 
 Sulphurretted hydrogen, 92. 
 Syenite, 154, 157. 
 
 Sylvan, 119. 
 
 Sylvine, 114. 
 
 Tablespar, 63. 
 
 Talc, 59, 64. 
 
 Talcose slate, 160. 
 
 Tantalite, 139. 
 
 Tellurium, native, 119. 
 
 graphic, 119. 
 
 black, 120. 
 
 Tennantite, 98. 
 
 Thallite, 48. 
 
 Thenardite, 112. 
 
 Thomsonite, 56. 
 
 Thulite, 48. 
 
 Tile ore, 149. 
 
 Tin pyrites, 98. 
 
 Tinstone, 131. 
 
 Titanite, 137. 
 
 Titanium, 137. 
 
 Toadstone, 162. 
 
 Topaz, 58. 
 
 Touchstone, 40. 
 
 Tourmaline, 60. 
 
 Trachyte, 162. 
 
 Trap, 162. 
 
 Tremolite, 70. 
 
 Triphane, 52. 
 
 Triphylline, 123. 
 
 Triplite, 123. 
 
 Tufa, 83, 171. 
 
 Tungstic ochre, 139. 
 Tungstate of iron, 140. 
 
 lead, 140. 
 
 lime, 140. 
 
 Turquoise, 122. 
 
 Umber, 146. 
 
 Uran mica, 124. 
 
 ochre, 142. 
 
 Variegated copper ore, 96. 
 Vauquelinite, 141. 
 
 Verd antique, 66, 163, 173. 
 Vermilion, 92. 
 
 Vert d’Egypte, 173. 
 
 Vitreous copper ore, 96. 
 
 quartz, 35. 
 
 silver ore, 94. 
 
 Volcanic glass, 53. 
 
 Wacke, 162. 
 
 Wagnerite, 122. 
 
 Water, 89. 
 
 Wavellite, 121. 
 
 Websterite, 107. 
 
 Wernerite, 48. 
 
 Whetstone, 165. 
 
 White lead ore, 87. 
 
 vitriol, 113. 
 
 Witherite, 87. 
 
 Wolfram, 140. 
 
 Wollastonite, 63. 
 
 Wood-tin, 131. 
 
 copper, 126. 
 
 Yellow ochre, 146. 
 
 orpiment, 105. 
 
 Yenite, 71. 
 
 Yttrotantalite, 139. 
 
 Zeolite, 55. 
 
 Zinc, 72, 86, 101, 113, 136. 
 Zircon, 62. 
 
 Zinkenite, 103. 
 
 Zoisite, 49. 
 
9tobert&emtnt 
 
 MR. TENNANT, 
 
 Mineralogist to Her Majesty, 
 
 IVES private instruction in Mineralogy and Geology, at his resident \ 
 
 Ur No. 149, Strand, London. He can supply Elementary Collections 
 at 2, 5, 10, 20, 50, to 100 guineas each, and every requisite to assist those 
 commencing the study of these interesting branches of Science, a know- 
 ledge of which affords so much pleasure to the traveller in all parts of the 
 
 world. 
 
 A Collection for Five Guineas, which will illustrate the recent works on 
 Geology by Lyell, Mantell, and others, contains 200 specimens, in a plain 
 Mahogany Cabinet, with five trays, comprising the following specimens, 
 viz. : — 
 
 Minerals which are either the components of Rocks, or occasionally 
 imbedded in them : — Quartz, Agate, Chalcedony, Jasper, Garnet, Zeolite, 
 Hornblende, Augite, Asbestus, Felspar, Mica, Talc, Tourmaline, Calca- 
 reous Spar, Fluor, Selenite, Baryta, Strontia, Salt, Sulphur, Plumbago, 
 Bitumen, &c. 
 
 Native Metals, or Metalliferous Minerals ; — these are found in 
 masses or beds, in veins, and occasionally in the beds of rivers. Speci- 
 mens of the following Metallic Ores are put in the Cabinet : — Iron, Man- 
 ganese, Lead, Tin, Zinc, Copper, Antimony, Silver, Gold, Platina, &c. 
 
 Rocks : — Granite, Gneiss, Mica-slate, Clay-slate, Porphyry, Serpentine. 
 Sandstones, Limestones, Basalt, Lavas, &c. 
 
 Palaeozoic Fossils, from the Llandeilo, Wenlock, Ludlow, Devonian, 
 and Carboniferous Rocks. 
 
 Secondary Fossils, from the Lias, Oolite, Wealden, and Cretaceous 
 Groups. 
 
 Tertiary Fosstls, from the Plastic-clay, London-clay, Crag, &c. 
 
 In the more expensive Collections some of the Specimens are rare, and 
 all more select. 
 
 Mr. Tennant bought at the Stowe sale the Duke of Buckingham's 
 Collection. It contains upwards of 3,000 Specimens, many of which are 
 of great value and interest, having refused £25 for one specimen and £30 
 for another. Price of the Collection, including two Cabinets with sixty 
 drawers, 1,000 Guineas. 
 
 Persons commencing the study of Geology and Mineralogy can be fur- 
 nished with Geological Maps, Hammers, Blowpipes, Magnifying Glasses, 
 and all the recent publications relating to Mineralogy, Geology, Con- 
 chology, and Chemistry ; also single specimens of recent Shells, Minerals, 
 and Fossils. 
 
 SOPWITH’S MODELS. 
 
 Mr. Tennant is agent for the sale of Sopwith's Geological Models, 
 which can be had in sets from £2 to £5 each, with letter-press de- 
 scription. 
 
 No. 149, Strand , London , October , 1855. 
 
THE FOLLOWING ARE 
 
 WORKS ON NAVAL ARCHITECTURE. 
 
 PUBLISHED BY MR. WEALE. 
 
 In 1 volume, 4to. text, and a large atlas folio volume of plates, half-bound. 
 Price 61. 6s. 
 
 THE ELEMENTS AND PRACTICE OE NAVAL 
 
 ARCHITECTURE ; or, a Treatise on Ship Building, theoretical 
 and practical, on the best principles established in Great Britain ; with 
 copious Tables of Dimensions, Scantlings, &c. The third edition, with 
 an Appendix, containing the principles and practice of constructing 
 the Royal and Mercantile Navies, as invented and introduced by Sir 
 Robert Seppings, Surveyor of the Navy. By John Knowles, F.R.S. 
 Illustrated with a Series of large Draughts and numerous smaller 
 Engravings. 
 
 LIST OF PLATES. 
 
 Perspective of the frame of a 100-gun 
 ship. 
 
 Construction of an arch, circles, &c. 
 Cones. 
 
 Capstans, crabs. 
 
 Conducting bodies and bars. 
 
 Floating bodies. 
 
 Representation of a flying proa. 
 Experiments on stability. 
 
 Scale of solidity of tonnage and dis- 
 placen ents. 
 
 Machines for driving and drawing bolts. 
 Longitudinal section and plan of a 74- 
 gun ship. 
 
 Plates of Details. — The following are exceedingly large : — 
 
 Construction 1. Draught of a ship pro- 
 osed to carry 80 guns upon two 
 ecks, with details. 
 
 2. Disposition of the frame 
 
 for a ship of 80 guns. 
 
 3. The planking expanded 
 
 of the 80-gun ship. 
 
 4. Profile of the inboard 
 
 works of the 80-gun ship. 
 
 5. Plans of the gun deck 
 
 and orlop of ditto. 
 
 6. Plans of the quarter 
 
 deck, forecastle, and upper deck of 
 ditto. % 
 
 7. Main gear capstan of 
 
 an 80-gun ship, windlass, &c., and 
 details. 
 
 8. Midship section of a 
 
 74-gun ship ; midship section of a 74- 
 gun ship, as proposed by Mr. Snod- 
 
 grass; midship section of a 36-gun 
 frigate ; midship section of a 36-gun 
 frigate, as proposed by Mr. Snodgrass ; 
 sketches of a new plan proposed for 
 framing ships, and of the best mode 
 of adopting iron-work in the con- 
 struction, and other details. 
 
 Construction 9. Sheer draught and plans 
 of a 40-gun trigate, with launch, &c. 
 
 10. Sheer draught, half- 
 breadth and body plans of a sloop 
 of war. 
 
 11. Draught of the “Dart” 
 
 and “Arrow” sloops, as designed by 
 General Bentham. 
 
 12. A brig of war, 18 guns. 
 
 13. Inboard works of ditto. 
 
 14. • Plans of the upper and 
 
 lower decks and platforms of a brig 
 of war. 
 
2 
 
 WORKS ON NAVAL ARCHITECTURE 
 
 Construction 15. Yacht “ Royal Sove- 
 reign.” 
 
 16. Yacht built for the 
 
 Prince Royal of Denmark. 
 
 • 17. Plans and Section o. 
 
 the interior of a fire-ship. 
 
 18. Draught and plans of 
 
 a bomb vessel. 
 
 19. A cutter upon a new 
 
 construction, with mode of fitting 
 sliding keels. 
 
 20. Sheer draught, half- 
 breadth and body plans of an East 
 Indiaman. 
 
 21. Sheer draught, half- 
 breadth and body plans of a West 
 Indiaman. 
 
 22. A collier brig of 170 tons. 
 
 23. A Virginia-built boat 
 
 fitted for a privateer. 
 
 24. A fast sailing schooner. 
 
 25. A Virginia pilot boat. 
 
 26. A Berwick smack. 
 
 27. A sloop of 60 tons in 
 
 the London trade, particularly dis- 
 tinguished for her capacity and velo- 
 city. 
 
 28. A Southampton fishing 
 
 hoy. 
 
 29. The long boat of an 80- 
 
 gun ship, showing the nature and 
 construction by whole moulding. 
 
 Construction 30. A launch, pinnace, 
 eight-oared cutter, yawl, &c. 
 
 31. Wherry, life-boat, whale 
 
 boat, a gig, a swift rowing boat. 
 
 32. Laying off, plan of the 
 
 fore-body, sheer, and half-breadth 
 plan of the fore-body, belonging to 
 the square bodies, &c. 
 
 33. Plan of the after-body, 
 
 sheer, and half-breadth plans of the 
 after-body, &c. 
 
 34. After-body plan, fore- 
 body plan, sheer and half-breadth 
 plans of the after-cant body, sheer, 
 and half-breadth plans of the fore- 
 cant body. 
 
 35. Horizontal transoms, 
 
 cant transoms, sheer plan, body plan, 
 &c. 
 
 36. Square tuck, body 
 
 plans, sheer and half-breadth plans. 
 
 37. Hawse pieces, cant 
 
 hawse pieces, &c. 
 
 38. Laying off of the stem, 
 
 laying off of the harpins, plan of the 
 stem, sheer plans, body plans. 
 
 39. Plans, elevations, and 
 
 sections of the different contrivances 
 for fitting the store-rooms, &c. on 
 the orlop of an 80-gun ship, showing 
 the method of fitting all ships of the 
 line in future. 
 
 II. 
 
 Drawn and Engraved with Dimensions, 8vo. text, and folio plates, Price 12s. 
 
 THE NAVAL ARCHITECT’S PORTFOLIO, and the 
 
 Student’s Practical Instructor in the Construction and Draughting of 
 Ships for War, Mercantile, and Steam-Packet Service — Iron and 
 Timber. By H. A. Summerfeldt, Lieutenant in the Royal Norwegian 
 Navy. 
 
 in. 
 
 In 3 parts or volumes, in 12mo, with numerous plates and woodcuts, price 35. 
 
 RUDIMENTS OE NAVAL ARCHITECTURE; or, an 
 
 Exposition of the Elementary Principles of the Science, and 
 
 THE PRACTICAL APPLICATION TO NAVAL CONSTRUCTION, for the Use of 
 
 Beginners. By James Peake, Naval Architect. 
 
 IV. 
 
 In 12mo, with numerous woodcuts, price 15. 
 
 HINTS ON THE PRINCIPLES WHICH SHOULD 
 
 REGULATE THE FORM OF SHIPS AND BOATS ; derived from 
 Original Experiments. By William Bland, Esq., Author of “On the 
 Principles of Construction of Arches,” &c. 
 
PUBLISHED BY ME. WEALE, 
 
 3 
 
 y. 
 
 The plates in large atlas folio, text in folio, price 4 1. 4s 
 
 NAVAL AECHITECTUEE ; or, The Eudiments ahd 
 
 Rules of Ship Building ; exemplified in a Series of Draughts and 
 Plans, with Observations tending to the Improvement of that important 
 Art. By Marmaduke Stalkartt, N.A. 
 
 THE PLATES CONSIST OF — 
 
 1. A long boat for a third-rate, six 
 figures of various draughts. 
 
 2. A yacht of 141 tons, ten figures of 
 several draughts. 
 
 3. A sloop, 331 tons, sheer draught and 
 bottom, fore and aft-bodies. 
 
 4. A sloop of war, cant timbers. 
 
 5. The bottom and top side. 
 
 6. 44-gun frigate, fore and aft, and 
 bottom, a very fine and large en- 
 graving. 
 
 7. Draughts, several. 
 
 8. The shift of the planks in the top 
 
 side, and the dispositions of the tim- 
 bers in ditto. 
 
 9. 74-gun ship, sheer draught and 
 bottom, fore and aft-bodies. 
 
 10. Draughts, several. 
 
 11. Right aft, a level view of the stern 
 of a 74-gun ship, side view of the 
 head and quarter-gallery, &c. 
 
 12. A cutter, draughts, &c. 
 
 13. Exact method of ending the lines 
 of different sections. 
 
 14. A frigate, sheer draught, bottom, 
 fore and aft-bodies. 
 
 These plates exhibit fineness and correctness of drawing and engraving, and 
 upon a large scale of rare occurrence. 
 
 STEAM NAVIGATION. 
 
 VI. 
 
 In atlas folio size, with 25 very finely engraved plates by Le Keux, price 25 s. 
 
 THE GREAT BRITAIN ATLANTIC STEAM SHIP 
 
 of 3500 tons, constructed of iron, with engines of 1000 to 2000 horse- 
 power, and the screw propeller; with scales and figured dimensions 
 to all the parts. 
 
 LIST OF PLATES OF THE GREAT BRITAIN. 
 
 1. Section of fore-end of engine-room, 
 looking aft. 
 
 2. Section at after-end of the boilers. 
 
 3. Section through the centre part of 
 the engine-room, looking forward. 
 
 4. 5. Plans, elevations, and sections of 
 the cylinders. 
 
 6, 7. Main driving shafts and cranks, 
 details. 
 
 8, 9. Section at the fore-end of the 
 boilers. 
 
 10, 11. Air-pump, connecting-rod, ele- 
 vation and plan of the parallel motion, 
 air-pumps. 
 
 12, 13. Piston, rods, and parallel mo- 
 tion, blocks, with plan. 
 
 14, 15. Section showing the manner of 
 
 carrying the cargo deck, and dispo- 
 sition of the plate-sleepers in the 
 ship’s bottom, after end. 
 
 16, 17. Section at the after-end of the 
 vessel, showing sleepers and lower 
 cargo deck. 
 
 18, 19. Upper cargo deck, forward, 
 showing the mode of fixing to the 
 sides of the vessel. 
 
 20, 21. Plan of the engine and boiler- 
 room, upper deck. 
 
 22, 23. Longitudinal section through 
 the engines and boilers. 
 
 24, 25. End elevation of the screw pro- 
 peller; elevation of the after-end of 
 the vessel, showing screw propeller 
 and rudder. 
 
4 
 
 WORKS ON NATAL ARCHITECTURE 
 
 VII. 
 
 In one very large-sized plate, finely engraved by Lowry, price 10s. with scales 
 and measures, 
 
 THE SHEER DRAUGHT, BODY PLAN, AND 
 
 BOTTOM OF THE IRON SHIP GREAT BRITAIN. 
 
 VIII. 
 
 Collected and bound uniformly in one folio volume, with the text in medium 
 quarto, half-cloth boards, price 51. 15s. Qd. ; forming a complete and separate 
 work from any edition of Tredgold on the Steam Engine. 
 
 APPENDICES TO THE ELABORATE EDITION OF 
 
 TREDGOLD ON THE STEAM ENGINE, AND ON 
 
 STEAM NAVIGATION, complete ; being the Appendices A, B, C, D, 
 E, F, and G, and not included in the new edition of Tredgold ; com- 
 prising very amply illustrated subjects on Steam Navigation, Steam 
 Vessels, both of iron and timber; Steam Engine in the Government 
 Arsenal, Woolwich ; Marine Engines ; an investigation and complete 
 development of Screw propelling ; and an elaborate Treatise and 
 detailed Illustrations of the Cornish Engine, &c. 
 
 The Engravings are on a large scale, for practical use, and were 
 drawn, explained, and corrected under the direction of the following 
 scientific gentlemen : Messrs. Laird, Liverpool ; Seaward, Limehouse ; 
 Fairbairn; Oliver Lang, H.M. Shipwright, Woolwich; William Pitcher 
 Northfleet; Miller & Ravenhill; Sir William Symonds, &c. &c. 
 
 APPENDIX A, B. 
 
 LIST OF SUBJECTS AND PLATES, 
 
 Iron steam-yacht “ Glow-worm,” con- 
 structed by Mr. J. Laird, Birkenhead. 
 
 Iron steam-ship “ Rainbow,” belonging 
 to the General Steam Navigation 
 Company, draught lines at bottom, 
 fore-body to a large scale, by Mr. J. 
 Laird. 
 
 Plans of the engines of 90 horse-power 
 each, 50-inch cylinders, 4-6 stroke, 
 made by G. Forrester & Co., Liver- 
 pool, and fitted on board the “Rain- 
 bow.” 
 
 Side elevation and section of ditto. 
 
 Transverse section of ditto. 
 
 Draught of the American armed steam- 
 ship “ Fulton. ” Half the main 
 breadth, 17 feet ; distance between 
 the water lines, 2 feet ; fore and after 
 body precisely alike. 
 
 Plans of upper and lower deck of the 
 Admiralty yacht “Black Eagle,” 
 with fittings, &c. 
 
 Plans of upper and lower decks of the 
 iron steam-yacht “Nevka,” built for 
 the Empress of Russia, by Messrs. 
 Fairbairn & Co. 
 
 Several of these plates a; 
 
 Draught, section, and lines of the 
 “Nevka.” 
 
 Cross section of ditto, showing engines, 
 construction of vessel, and paddles. 
 
 Body plan, cross section, and saloon ; 
 showing joinings, fittings, and deco- 
 rations. 
 
 Mr. John Hague’s 12-horse condensing 
 engine, in operation at the Arsenal 
 of Woolwich : elevation, with dimen- 
 sions of parts and references. 
 
 Longitudinal section, ditto, ditto. 
 
 Plan, ditto, ditto. 
 
 Section, showing boiler, &c., ditto. 
 
 End section, showing furnace, &c., ditto. 
 
 Mr. Lang’s mode of connecting the 
 stem, stem-post, and keel together, 
 for any description of vessel ; and 
 Mr. Lang’s method of framing the 
 ribs and keels of steam vessels, with 
 a plan of timbers explained, sectional 
 parts and dimensions. 
 
 Chapman’s draught lines of bottom, fore 
 and aft bodies ; and Mr. Whitelaw’s 
 of Glasgow, new contrivances in the 
 steam engine. 
 
 of large size, and useful to practical men. 
 
PUBLISHED BY MB. WEALE, 
 
 5 
 
 APPENDIX C.— Price 14s. 
 
 LIST OF SUBJECTS AND PLATES. 
 
 General elevation of the starboard 
 engine and boilers of the “ Cyclops,” 
 showing the relative position of all 
 the parts connected therewith. 
 
 End views of both engines at the paddle 
 shaft, with a section of the vessel 
 taken at the same point, &c. 
 
 Front elevation, section in elevation, 
 and plan of the cylinder, steam 
 nozzles, and slide gear, with details 
 of the eccentric, &c. 
 
 Different views of the condensing appa- 
 ratus, feed and bilge pumps, &c. 
 Details of the parallel motion, connect- 
 ing-rod and piston, cross-head, &c. 
 Elevations of part of one paddle-whee. 
 and shaft, &c. 
 
 Front elevation of two boilers, &c. 
 Transverse sections of two boilers, &c. 
 Plans of the four boilers, &c. 
 Appendages to the boilers, &c. 
 
 Together with several details scattered over the plates. 
 
 APPENDIX D.— Price 10s. 6d. 
 
 THE ARCHIMEDEAN SCREW, or SUBMARINE PROPELLER, illus- 
 trated ; describing also the inventions and experiments on this 
 important subject. 
 
 APPENDIX E, 
 
 LIST OF 
 
 West Indian mail steam -packet “ Isis,” 
 by Mr. Pitcher, Northfleet. 
 
 The “Orion,” Ipswich steam-packet 
 vessel, by Mr. Bead, Ipswich. 
 
 Engines of the “Isis,” by Messrs. 
 Miller & Co. 
 
 The Plates are very 
 
 Sheer draught and profile of inboard 
 works and after-body of the Boyal 
 mail West India packet “Isis.” 
 
 Lines of bottom, ditto. 
 
 Plan of spar-deck, showing Captain 
 Smith’s life-boats. 
 
 Plans of upper and lower decks, ditto. 
 
 Midship section, ditto. 
 
 Sheer draught, lines of bottom, and 
 after body of the “Orion,” Ipswich 
 iron packet. 
 
 Plan of deck of ditto. 
 
 Longitudinal elevation of one of the 
 engines of the “Isis.” 
 
 End elevation of ditto, showing paddles, 
 shaft, and construction of vessel. 
 
 Plan of the engines of the “Isis,”to- 
 
 F. — Price 1?. 5s. 
 
 H.M. Steam-frigate of war “Cyclops,” 
 by Sir Wm. Symonds, Surveyor of 
 the Navy. 
 
 Engines of the “Dee” and “Solway” 
 West Indian mail steam-packets, by 
 Messrs. Scott, Sinclair, & Co. 
 
 •ge, and consist of — 
 
 gether with the boilers, engine-room, 
 &c. 
 
 Sheer draught, profile of inboard works, 
 with lines of bottom, and after body, 
 of her Majesty’s steam-frigate 
 “ Cyclops,” 
 
 Plans of upper and lower decks of ditto. 
 
 Sketch of spars, sails, &c. of ditto. 
 
 Transverse section, and part of frame- 
 work of ditto, showing the admirable 
 construction of this vessel. 
 
 Longitudinal elevation of one of the 
 engines of the Boyal mail West India 
 packets “Dee” and “Solway.” 
 
 Two end views of ditto. 
 
 Plan of Ditto. 
 
 APPENDIX G. — Price 11. 12s. 
 
 THE CORNISH PUMPING ENGINE ; designed and constructed at the 
 Hayle Copper-House in Cornwall, under the superintendence of Captain 
 J enkins ; erected and now on duty at the coal mines of Languin, 
 Department of the Loire Inf^rieur, near Nantes. Nine elaborate 
 drawings, historically and scientifically described. 
 
 LIST OF PLATES. 
 
 Plan of the engines and boilers. — Side 
 elevation of engine. 
 
 End view of engine and boilers. 
 
 Details of cylinder, nozzles, valves, 
 hand-gearing, &c. 
 
 The text in a 4to volume, ; 
 
 Details of air-pump, condensers, feed- 
 pump, &c. 
 
 Ditto boiler and boiler apparatus. 
 Elevation and sections of pumps and 
 pit-work. 
 
 , plates in a large folio size. 
 
6 WORKS ON STORMS PUBLISHED BY MR. WE ALE 
 
 ALSO, STORMS. 
 
 Third edition, in royal 8vo, boards, with 13 charts, <fcc., price 125. 
 
 AN ATTEMPT TO DEVELOP THE LAW OP 
 
 STORMS, by means of facts arranged according to place and time ; 
 and Renee to point out a cause for the Variable Winds, with a view 
 to Practical Use in Navigation. By Colonel Sir W. Reid, K.C.B., 
 and R.E., Governor of Malta. 
 
 x. 
 
 In royal 8vo, uniform with the preceding, price 95. with Charts and wood-cuts. 
 
 THE PROGRESS OP THE DEVELOPMENT OP 
 THE LAW OF STORMS, AND OF THE VARIABLE WINDS; 
 with the practical application of the subject to Navigation. By Colonel 
 Sir W. Reid, K.C.B., F.R.S., &c. &c. 
 
 XI. 
 
 In royal 8vo, uniform with the preceding, price Is. 6d. 
 
 NABBATIVES (Written by Sea Commanders) ILLUS- 
 TRATIVE OF THE LAW OF STORMS, and of its practical applica- 
 tion to Navigation. No. 1, The * Blenheim 9 Hurricane of 1851, with 
 Diagrams. 
 
 4 - 
 
 XII. 
 
 In one small volume, with many plates and wood-cuts, second edition, corrected 
 and improved, neatly bound, 45. 6d. 
 
 TEMPLETON’S OPEBATIVE MECHANIC’S WOBK- 
 SHOP COMPANION, AND THE SCIENTIFIC GENTLEMAN’S 
 PRACTICAL ASSISTANT ; containing a great variety of the most 
 useful Rules in Mechanical Science, divested of mathematical com- 
 plexity ; with numerous Tables of practical data and calculated results, 
 for facilitating mechanical and commercial transactions. 
 
In Folio, with 100 Engravings, price 100 Francs French, 
 or Four Pounds sterling . 
 
 ANCIENT SMITHERY 
 
 OF 
 
 GOLD, SILVER, COPPER, AND IRON, 
 
 MEASURED AND DRAWN 
 
 cfFrom ancient iifroMsi, 
 
 AND COMPRISED IN 
 
 ONE HUNDRED FULL-PAGED EXAMPLES, 
 
 WITH 
 
 AMPLE DETAILS OF THE MIDDLE AGE. 
 
 EXAMPLES FOP. INTERIOR DECORATIONS FOR DOMESTIC AND 
 ECCLESIASTICAL PURPOSES. 
 
 JUST ISSUED AT BRUGES, 
 
 AND NOW SOLD BY 
 
 JOHN WEALE, 
 
 59, HIGH HOLBORN. 
 
NEWLY-IMPORTED WORKS FROM FRANCE 
 
 OK 
 
 DESIGN IN ART. 
 
 'J'HE following very superior Works, which are elaborately 
 illustrated by Engravings, show, by educational means, the 
 correct mode of Instruction in Design for elementary purposes, 
 and for practice in drawing accurately, with elegance of style, 
 in the Fine and Useful Arts. 
 
 To the Trustees of Government Schools of Design, Mechanic 
 Institutes, Institutions of Civil and Mechanical Engineers, and 
 to Professional Men, the following list is especially addressed. 
 
 i. 
 
 COURS ELEMENTAIRES DE LAYIS APPLIQUE 
 
 A L’ARCHITECTURE. Folio volume, containing 40 elaborately 
 engraved plates, in Shadows and Colours, very finely executed by 
 the best artists of France. Price 21. Paris, 50/. 
 
 II. 
 
 COUPS ELEMENTAIRES DE LAYIS APPLIQUE 
 
 A MECANIQUE. Folio volume, containing 40 elaborately en- 
 graved plates, in Shadows and Colours, very finely executed by 
 the best artists of France. Price 21. Paris, 50/. 
 
 III. 
 
 COURS ELEMENTAIRES DE LAYIS APPLIQUE 
 
 A ORNEMENTATION. Folio volume, containing 20 elaborately 
 engraved plates, in Shadows and Colours, very finely executed by 
 the best artists of France. Price 11. Paris, 25/. 
 
 IV. 
 
 ETUDES PROGRESSIVES ET COMPLETES 
 
 D’ARCHITECTURE ET DE LAVIS. Par J. B. TRIPON. Large 
 folio, 24 fine plates, comprising the orders of Architecture, 
 Mouldings with Profiles, Ornaments, and Forms of their Propor- 
 tion, Art of Shadowing Doors, Balusters, Parterres, &c. &c. &c. 
 Price 11. 4s. Paris, 36/. 
 
 V. 
 
 SPECIMENS FOR DRAWING, SHADOWING, 
 
 AND ELABORATING THE EXTERIOR AND INTERIOR OF 
 HOUSES, drawn on a large scale in large Atlas folio, consisting 
 of Style Renaissance — Old French, Modern French, Italian, Vene- 
 tian, English, and Parisian. 12 plates, very finely executed. 
 Price 15s. Paris, 20/. 
 
In one Volume large 8ro., with 13 Plates , Price One Guinea , 
 in half-morocco binding , 
 
 MATHEMATICS 
 
 FOR 
 
 PRACTICAL MEN: 
 
 BEING 
 
 A COMMON-PLACE BOOK 
 
 OF 
 
 PURE AND MIXED MATHEMATICS, 
 
 DESIGNED CHIEFLY FOR THE USE OF 
 
 CIVIL ENGINEERS, ARCHITECTS, AND SURVEYORS. 
 
 BY OLINTHUS GREGORY, LL.D., F.R.A.S. 
 
 THIRD EDITION, REVISED AND ENLARGED. 
 
 BY HENRY LAW, 
 
 CIVIL ENGINEER. 
 
MATHEMATICS FOR PRACTICAL MEN 
 
 SR— 
 
 10 
 
 CONTENTS. 
 
 PART I.— PURE MATHEMATICS 
 
 CHAPTER I. — Arithmetic. 
 
 Sect. 
 
 1. Definitions and Notation. 
 
 2. Addition of Whole Numbers. 
 
 3. Subtraction of Whole Numbers. 
 
 4. Multiplication of Whole Numbers. 
 
 5. Division of Whole Numbers. — Proof of 
 
 the first Four Rules of Arithmetic. 
 
 6. Vulgar Fractions.— Reduction of Vul- 
 
 gar Fractions. — Addition and Sub- 
 traction of Vulgar Fractions. — Mul- 
 tiplication and Division of Vulgar 
 Fractions. 
 
 7. Decimal Fractions. — Reduction of 
 
 Decimals. — Addition and Subtrac- 
 tion of Decimals. — Multiplication 
 and Division of Decimals. 
 
 8. Complex Fractions used in the Arts 
 
 and Commerce. — Reduction. — Addi- 
 tion. — Subtraction and Multiplica- 
 tion. — Division. — Duodecimals. 
 
 9. Powers and Roots. — Evolution. 
 
 10. Proportion. — Rule of Three. — Deter- 
 
 mination of Ratios. 
 
 11. Logarithmic Arithmetic. — Use of the 
 
 Tables. — Multiplication and Division 
 by Logarithms. — Proportion, or the 
 Rule of Three, by Logarithms. — 
 Evolution and Involution by Log- 
 arithms. 
 
 12. Properties of Numbers. 
 
 Sect. 
 
 9. Quadratic Equations. 
 
 10. Equations in General. 
 
 11. Progression. — Arithmetical Progres- 
 
 sion. — Geometrical Progression. 
 
 12. Fractional and Negative Exponents. 
 
 13. Logarithms. 
 
 14. Computation of Formulae. 
 
 CHAPTER III.— Geometry. 
 
 1. Definitions. 
 
 2. Of Angles, and Right Lines, and their 
 
 Rectangles. 
 
 3. Of Triangles. 
 
 4. Of Quadrilaterals and Polygons. 
 
 5. Of the Circle, and Inscribed and Cir- 
 
 cumscribed Figures. 
 
 6. Of Planes and Solids. 
 
 7. Practical Geometry. 
 
 CHAPTER IV. — Mensuration. 
 
 1. Weights and Measures. — 1. Measures 
 
 of Length. — 2. Measures of Surface. 
 — 3. Measures of Solidity and Ca- 
 pacity. — 4. Measures of Weight. — 
 5. Angular Measure. — 6. Measure of 
 Time. — Comparison of English and 
 French Weights and Measures. 
 
 2. Mensuration of Superficies. 
 
 3. Mensuration of Solids. 
 
 CHAPTER II. — Algebra. 
 
 CHAPTER V. — Trigonometry. 
 
 | 
 
 I 
 
 1. Definitions and Notation. 
 
 2. Addition and Subtraction. 
 
 3. Multiplication. 
 
 4. Division. 
 
 5. Involution. 
 
 C. Evolution. 
 
 7. Surds. — Reduction. — Addition, Sub- 
 
 traction, and Multiplication. — Di- 
 vision, Involution, and Evolution. 
 
 8. Simple Equations. — Extermination. — 
 
 Solution of General Problems. 
 
 1. Definitions and Trigonometrical For- 
 
 mulae. 
 
 2. Trigonometrical Tables. 
 
 3. General Propositions. 
 
 4. Solution of the Cases of Plane Trian- 
 
 gles. — Right-angled Plane Triangles. 
 
 5 . On the application of Trigonometry 
 
 to Measuring Heights and Distances. 
 • — Determination of Heights and 
 Distances by Approximate Mechani- 
 cal Methods. 
 
MATHEMATICS FOR 
 
 CHAPTER YI. — Conic Sections. 
 
 Sect. x 
 
 1. Definitions. 
 
 2. Properties of the Ellipse. — Problems 
 
 relating to the Ellipse. 
 
 3. Properties of the Hyperbola. — Pro- 
 
 blems relating to the Hyperbola. 
 
 4. Properties of the Parabola. — Problems 
 
 relating to the Parabola. 
 
 2. The Conchoid. 
 
 3. The Cissoid. 
 
 4. The Cycloid and Epicycloid, 
 
 5. The Quadratrix. 
 
 6. The Catenary. — Tables of Relations 
 
 of Catenarian Curves. 
 
 PART II.— MIXED MATHEMATICS. 
 
 CHAPTER I.— Mechanics in General. 
 
 CHAPTER II.— Statics. 
 
 1. Statical Equilibrium. 
 
 ; 2. Center of Gravity. 
 
 3. General application of the Principles 
 of Statics to the Equilibrium of 
 Structures. — Equilibrium of Piers 
 or Abutments. — Pressure of Earth 
 against Walls. — Thickness of Walls. 
 — Equilibrium of Polygons. — Sta- 
 bility of Arches. — Equilibrium of 
 Suspension Bridges. 
 
 CHAPTER III.— Dynamics. 
 
 I 1. General Definitions. 
 
 ! 2. On the General Laws of Uniform and 
 Variable Motion. — Motion uniformly 
 Accelerated. — Motion of Bodies un- 
 der the Action of Gravity — Motion 
 over a fixed Pulley. — Motion on 
 Inclined Planes. 
 
 3. Motions about a fixed Center, or Axis. 
 
 — Centers of Oscillation and Per- 
 cussion. — Simple and Compound 
 Pendulums. — Center of Gyration, 
 and the Principles of Rotation. — 
 Central Forces. — Inquiries connected 
 with Rotation and Central Forces. 
 
 4. Percussion or Collision of Bodies in 
 
 Motion. 
 
 5. On the Mechanical Powers. — Levers. 
 
 — Wheel and Axle. — Pulley. — In- 
 clined Plane. — Wedge and Screw. 
 
 ■® — 
 
 CHAPTER IV.— Hydrostatics. 
 
 1. General Definitions. 
 
 2. Pressure and Equilibrium of Non.- 
 
 elastic Fluids. 
 
 3. Floating Bodies. 
 
 4. Specific Gravities. 
 
 5. On Capillary Attraction. 
 
 CHAPTER Y. — Hydrodynamics. 
 
 1. Motion and Effluence of Liquids. 
 
 2. Motion of Water in Conduit Pipes 
 
 and Open Canals, over Weirs, &c. — 
 Velocities of Rivers. 
 
 3. Contrivances to Measure the Velocity 
 
 of Running Waters. 
 
 CHAPTER VI. — Pneumatics. 
 
 1. Weight and Equilibrium of Air and 
 
 Elastic Fluids. 
 
 2. Machines for Raising Water by the 
 
 Pressure of the Atmosphere. 
 
 3. Force of the Wind. 
 
 CHAPTER VII. — Mechanical Agents. 
 
 1. Water as a Mechanical Agent. 
 
 2. Air as a Mechanical Agent. — Cou- 
 
 lomb’s Experiments. 
 
 3. Mechanical Agents depending upon 
 
 Heat. The Steam Engine. — Table 
 of Pressure and Temperature of 
 Steam. — General Description of the 
 Mode of Action of the Steam Engine. 
 — Theory of the Steam Engine. — 
 Description of the various kinds of 
 
 & 
 
PRACTICAL MEN. 
 
 ormul'se for calcu- 1 3. 
 Power. — Practical pli- 1 , 
 
 4. 
 
 of the foregoing Formula^lfc^ 
 Animal Strength as a Mechanical Agent. 
 
 CHAPTER VIII. — Strength op 
 Materials. 
 
 L. Results of Experiments, and Principles 
 upon which they should be practically 
 applied. 
 
 2. Strength of Materials to Resist Tensile 
 and Crushing Strains. — Strength of 
 Columns. 
 
 Elasticity and Elongation of Bodies 
 subjected to a Crushing or Tensile 
 Strain. 
 
 On the Strength of Materials subjected 
 to a Transverse Strain. — Longi- 
 tudinal form of Beam of uniform 
 Strength. — Transverse Strength of 
 other Materials than Cast Iron. — 
 The Strength of Beams according to 
 the manner in which the Load is 
 distributed. 
 
 5. Elasticity of Bodies subjected to 
 
 Transverse Strain. 
 
 6. Strength of Materials to resist Torsion. 
 
 APPENDIX 
 
 I. Table of Logarithmic Differences. 
 
 II. Table of Logarithms of Numbers, from 1 to 100. 
 
 III. Table of Logarithms of Numbers, from 100 to 10,000. 
 
 IV. Table of Logarithmic Sines, Tangents, Secants, &c. 
 
 v! Table of Useful Factors, extending to several places of Decimals. 
 
 VI. Table of various Useful Numbers, with their Logarithms. 
 
 VII. A Table of the Diameters, Areas, and Circumferences of Circles and also the 
 
 sides of Equal Squares. 
 
 VIII. Table of the Relations of the Arc, Abscissa, Ordinate and Subnormal, m the 
 Catenary. 
 
 IX. Tables of the Lengths and Vibrations of Pendulums. 
 
 X. Table of Specific Gravities. 
 
 XI. Table of Weight of Materials frequently employed in Construction. 
 
 XII. Principles of Chronometers. 
 
 XIII. Select Mechanical Expedients. 
 
 XIV. Observations on the Effect of Old London Bridge on the Tides, &c. 
 
 XV. Professor Farish on Isometrical Perspective. 
 
 CATALOGUE OE BOOKS 
 
 ON 
 
 ARCHITECTURE AND ENGINEERING, CIVIL, MECHANICAL, 
 MILITARY, AND NAVAL— NEW AND OLD. 
 
 Together with an incorporated List of Members, &c., of the several Learned 
 Societies for the Promotion of Civil Architecture and Civil and 
 Mechanical Engineering, and an Index of Contents. 
 
 Price One Shilling . 
 
 JOHN WEALE, 59, HIGH HOLBORN.