O F THE U N IVER.5ITY or ILLINOIS 549 N542e 1873 Geol. GEOLOGY LIBRARY. . The person charging this material is re- sponsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN AUG 2 i m L161 — O-1096 ELEMENTS OF MI NEE A LOGY A GENERAL INTEODUCTION TO THE SCIENCE, WITH DESCEIPTIONS OF THE SPECIES BY JAMES NICOL, F.R.S.E., F.G.S., PROFESSOR OF NATURAL HISTORY IN THE UNIVERSITY OF ABERDEEN UNIVERSITYOF ILUMOISLIBB^ARY^^^^ SECOND EDITION uFBANA'CHAMPAKSN ' . GECIOGY Ellustrateti Numerous OTaotitute EDINBUEGH ADAM AND CHAELES BLACK 1873 Printed byV.. & R. Clakk, Edinburgh. PEEFACE. This Treatise was originally intended to furnish a summary of the leading principles and more important facts of Mineralogy, specially for the use of persons wishing to acquire a knowledge of the science, — some it might be as a branch of general education, others with a view to its practical applications to geology, mining, agriculture, or other connected pursuits. Hence the facts and principles were stated in the simplest language consistent with scientific accuracy, and the more important results ascertained in regard to the physical properties and chemical composition of mine- rals were given without those details which often prove more embarrassing than useful to the student. The call for a new edition shows that it has so far served the purpose for which it was prepared. But in the last few years most important additions have been made to this science. The forms and composition of many, even of the older known minerals, have been determined with more accuracy, and several highly interesting new species have been discovered. In the present edition this new matter has been introduced so far as consistent with the plan of the work. Every portion of it has been carefully revised and corrected, so iv PEEFACE. as to render the definitions and descriptions of the lead- ing minerals fuller, more precise, and more easily intel- ligible to the student. Supposed species, which have not stood the test of investigation, have been omitted, or are noticed only as varieties, while the more inte- resting of those recently discovered have taken their place. No change has been made on the classification, the mixed system being preferred, both as admitting of a more natural grouping of minerals, and as better adapted to promote the progress of the student than either a rigid chemical or crystallographic arrangement. The Author has been glad to find his views on this point confirmed by the adoption of like or identical groups and families of minerals in several recent publications on the subject. The Author regrets that the plan and limits of this treatise do not admit of full references to the many authors whose works and memoirs he has consulted, and to which he is indebted for much valuable material. In revising this volume he has found much assistance from the last edition of the admirable manual of Professor Naumann, whose system and symbols of the forms of crystals he retains, regarding them as simpler, more philosophical, more generally used, and thus also more useful, than any other. In the chemical department the works of Eammelsberg are still our best guides. The changes in that science are, however, one of the chief difficulties the teacher of mineralogy has to encounter. Though, for reasons stated in the text, and on the advice of some esteemed scientific friends and PKEFACE. V teachers of the science, he has chiefly retained the old formulse, he has also given others of the more import- ant species, conformable to the new views. It need hardly be stated that the chemical composition, as given in per cents, is the same on either theory. Those families and species which, from their fre- quent occurrence, their geological importance as con- stituents of rock formations, or from their economic properties or products, are most worthy of notice, have now been indicated throughout, — the most important by two the less by one (*) asterisk. For a first course in the science, or for reading our best works on geology, the former selection (**) contains almost all the species to which the student's attention need be specially directed. In conclusion, the Author would anew express his trust that, notwithstanding any errors or omissions, which in a work so full of minute facts and figures he can hardly hope to have avoided, this volume may still continue to promote — what was his chief object in first preparing it — an increased knowledge of this most important and beautiful portion of the works of the Creator. Aberdeen, l^th Jidy 1873. Digitized by tlie Internet Arcliive in 2015 littps://arcliive.org/details/elementsofmineraOOnicli CONTENTS. PAGE Introduction . . . . . . . i PAET 1. TERMINOLOGY. Chap. I, Foem of Minerals . . . . .3 Ceystals ...... 3 Systems of Crystallisation ... 4 1. Tesseral System .... 5 2. Tetragonal System . . .17 3. Hexagonal . . . .21 4. Rhombic . . . . .26 5. Monoclinic . . . .30 6. Triclinic . . . . .33 Imperfections of Crystals . . .35 Goniometer and Measurement of Crystals . 38 Macles or Twin Crystals . . .41 Crystalline Aggregates . . . .49 Pseudomorphism . . . .52 Chap. II. Physical Properties of Minerals - . .54 Cleavage and Fracture . . . .54 Hardness and Tenacity . . . .56 Specific Gravity . . . .58 Optical Relations . . . .60 Double Refraction . . . .60 Polarisation . . . . .62 Pleochroism . . . . .65 Lustre ..... 66 Colour . . . . .68 viii CONTENTS. Chap. 11. Physical Properties op Minerals — continued. Phospliorescence Electricity Magnetism Smell, Taste, Touch Chap. III. Chemical Properties of Minerals Composition of Minerals Table of Elements Table of Oxygen Compounds Influence of Chemical Character Dimorphism Isomorphism Chemical Keaction of Minerals Use of Blowpipe Eeagents Non-metallic Elements . Alkalies and Earths Metals . Chap. IY. Classification of Minerals Mineral Species Systems of Classification Mode of Description 70 71 72 72 73 74 76 79 82 82 83 85 85 87 89 91 92 97 97 98 102 PAKT II. DESCRIPTION OF MINERAL SPECIES. Order I. The Oxidised Stones II. Saline Stones III. Saline Ores IV. Oxidised Ores V. Native Metals VI. Sulphuretted Metals VII. Inflammables 103 190 222 252 274 287 314 MINEEALOGY. Mineralogy is sometimes understood as comprising the natural history of every portion of inorganic nature. Here we consider it as limited to the natural history of simple minerals or mineral species. In the strictest sense, a mine- ral species is a natural inorganic body, possessing a definite chemical composition, and assuming a regular determinate form or series of forms. This definition excludes many bodies often regarded as minerals : as, all the artificial salts of the chemist, all the inorganic secretions of plants and animals, all the remains of former living beings now imbed- ded in rocks. Some substances originally organic products have indeed, by common consent, found a place in mineral systems, as coal, amber, and mineral resins ; but this is a departure from the strictness of the definition, and in most cases had better have been avoided. So also some amor- phous substances, with no precise form or chemical com- position, as some kinds of clay, have been introduced into works on mineralogy, but we believe often improperly, and with no beneficial result. Aggregates of simple minerals or rocks are likewise excluded from this science, though the various associations of minerals, their modes of occurrence, and their geological position, are important points in the history of the difi'erent species. One most important object of a treatise on mineralogy is to give such descriptions of minerals, their essential pro- perties and distinctive characters, as will enable the student to distinguish the various species, and to recognise them when he meets with them in nature. But to accomplish this he must first become acquainted with the terminology B 2 MINERALOGY. or nomenclature of the science ; that is, with the meaning of the terms used in describing these properties, and the various modifications they may undergo. With this is necessarily conjoined an account of the properties them- selves, and of the more general laws by which their various changes are regulated. Closely related to this is an ac- count of the system or classification, explaining the order in which the species are arranged, and the reasons for which it has been adopted. The second and most important part of mineralogy, to which the former is properly preparatory, is the physiography or description of the various species, pointing out the characters by which they may be recog- nised, and giving an account of their appearance or external aspect and forms ; their principal physical and chemical properties ; their mode of occurrence, with their geological and geographical distribution ; and their various uses, whether in nature or in the arts. Each of these depart- ments will be considered in the following treatise in the order just mentioned. PAET I.-TEEMINOLOGY. The more important properties of a mineral regarded as a body existing in space, and consisting of matter aggregated in a peculiar way, are — ^its form as shown in crystallisation ; its structure as determining its mode of cleavage and frac- ture ; its hardness and tenacity; its weight or specific gravity ] and its relations to light, heat, electricity, and magnetism. CHAPTER I. FORM OF MINERALS. Crystalline and Amorphous. — Mineral substances occur in two distinct modes of aggregation. Some consist of minute particles simply collected together, with no regularity of structure or constancy of external form, and are named amorphous. All fluid minerals are in this condition, together with some solid bodies, which appear to have condensed either from a gelatinous condition like opal, when they are named porodine, or from, a state of igneous fluidity like obsidian and glass, when they are named hyaline. The other class have their ultimate atoms evidently arranged according to definite law, and are named crystalline, when the regularity of structure appears only in the internal dis- position of the parts ; and crystallised, when it also produces a determinate external form, or a crystal. Faces, Edges, Angles, Axes of Crystals, — The word crys- tal in mineralogy designates a solid body exhibiting an 4 SYSTEMS OF CRYSTALLISATION. original (not artificial) more or less regular polyhedric form. It is bounded by plane surfaces, named faces, which intersect in straight lines or edges, and these again meet in points and form solid angles, bounded by three or more faces. The space occupied by a crystal is often named a form of crystallis- ation, which is thus the mathematical figure regarded as in- dependent of the matter that fills it. Crystals bounded by equal and similar faces are named simple forms. The cube or hexahedron (Fig. 1), bounded by six equal and similar squares ; the octahedron (Fig. 2), by eight equilateral tri- angles ; and the rhombohedron, by six rhombs, — are thus simple forms. Crystals of which all the faces are not equal and similar are named compound forms, or combinations, being regarded as produced by the union or combination of two or more simple forms. An axis of a crystal is a line passing through its centre and terminating either in the middle of two faces, or of two edges, or in two angles ; and axes ter- minating in similar parts of a crystal are named similar axes. In describing a crystal, one of its axes is supposed to be vertical or upright, and is then named the principal axis, and that axis is chosen which is the only one of its kind in the figure. Eound this axis the faces belonging to a certain form of crystal often group themselves in regular zones. A few other technical terms used in describing crystals will be explained as they occur. Sijstems of Crystallisation. — The forms of crystals that occur in nature seem almost innumerable. On examining them, however, more attentively, it is discovered that these forms can be arranged in certain groups, of which each member is intimately related to all the others — specially they all agree in the proportion of their axes and in the angles at which these intersect each other. Then they can all be deduced or derived from one simple form, or Primary form as it is named, by changes produced on it according to definite laws. When viewed in this manner, the vast variety of crystals occurring in nature may all be reduced to six distinct groups, or, as they are named, Systems of Crys- tallisation. The following are the names given to these systems of crystallisation in some of the best authors : — TESSEKAL SYSTEM. Naumann. I. Tesseral System. II. Tetragonal System. III. Hexagonal System. IV. Ehombic System. V. Monoclinic System. VI. Triclinic System. Mohs. Tessular. Pyramidal. Ehombohedral. Orthotype. Hemiorthotype. Anorthotype. Weiss and G. Rose. Regular. 2 and 1 axial, 3 and 1 axial. 1 and 1 axial. 2 and 1 membered. 1 and 1 membered. Miller names them — I. Cubic, II. Pyramidal, III. Ehom- bohedral, IV. Prismatic, V. Oblique, and VI. Anorthic. In the following treatise the terminology of Naumanu is adopted, his method of classifying and describing crystals appearing the simplest and best adapted to promote the pro- gress of the student. Formerly he named systems V. and VI. Monoclinohedric and Triclinohedric, but the shorter names are preferable. The first, or Tesseral System, named from tessera, a cube, which is one of the most frequent varieties, is characterised by three equal axes intersecting each other at right angles. Properly speaking, this system has no chief axis, as they are all similar, and with similar faces formed round them, so that any one axis may be placed upright in drawing and describing the crystals. Of these there are thirteen varieties, named from the number of their faces : — 1. One Tetrahedron, or form with four faces. 2. One Hexahedron, with six faces. 3. One Octahedron, with eight faces. 4. Four Dodecahedrons, with twelve faces. 5. Five Icositetrahedrons, with twenty-four faces. 6. One Tetracontaoctahedron, with forty-eight faces. The dodecahedrons are further distinguished, according to the form of their faces, into rhombic, trigonal, deltoid, and pentagonal dodecahedrons ; and some of the icositetra- hedrons have also received peculiar names. The following is a description, with figures, of the differ- ent forms above mentioned : — 1. The hexahedron or cube (Fig. 1) is bounded by six equal squares, has twelve edges, formed by faces meeting at 90°, and eight solid trigonal angles. The principal axes join the centre points of each two opposite faces. — Examples are fluor spar, galena, boracite. « 6 TESSERAL SYSTEM. 2, The octahedron (Fig. 2), bounded by eight equilateral triangles, has twelve equal edges, with planes meeting at Fig. 1. The Hexahedron. Fig- 2. The Octahedron. 109° 28', and six tetragonal angles. The principal axes join the opposite angles, two and two. — Examples, alum, spinel, magnetite. 3. The rhombic-dodecahedron (Fig. 3) is bounded by twelve equal and similar rhombs (diagonals as 1 and \/2), has twenty-four equal edges of 120°, and six tetragonal and eight trigonal angles. The principal axes join two opposite tetragonal angles.— Ex., garnet, boracite, cuprite. Fig. 3. Rhombic-dodecahedron. Fig. 4. Tetrakishexahedron. 4. The tetrakishexahedrons (variety of icositetrahedron. Fig. 4) are bounded by twenty-four isosceles triangles. FORMS OF CEYSTALS. 7 arranged in six groups of four each. They have twelve longer edges, which correspond to those of the primitive or inscribed cube, and twenty-four shorter edges placed over each of its faces. The angles are eight hexagonal and six tetragonal; the latter joined two and two by the three principal axes. This form varies in general aspect, approach- ing, on the one hand, to the cube ; on the other, to the rhombic-dodecahedron. — Ex., fluor spar, gold. 5. The triakisoctahedrons (variety of icositetrahedron, Fig. 5) are bounded by twenty-four isosceles triangles, in eight groups of three, and, like the previous form, vary in general aspect from the octahedron on one side, to the rhombic-dodecahedron on the other. The edges are twelve longer, corresponding mth those of the inscribed octahedron, and twenty-four shorter, three and three over each of the faces. The angles are eight trigonal and six ditetragonal (formed by eight faces) ; the latter angles joined two and two by the principal axes. — Ex., galena, diamond. Fig. 5. Triakisoctahedron. ' Fig. 6. Icositetrahedron. 6. The icositetrahedrons (most common variety. Fig. 6) are bounded by twenty-four deltoids or figures with four sides, of which two and two adjacent ones are equal. This fonn varies from the octahedron to the cube, sometimes ap- proaching the former and sometimes the latter in general aspect. The edges are twenty -four longer and twenty-four shorter. The angles are six tetragonal joined by the prin- cipal axes, eight trigonal, and twelve rhombic, or tetragonal with unequal angles. 8 TESSERAL SYSTEM. 7. The hexakisoctahedrons (Tig. 7), bounded by forty- eight scalene triangles, vary much in general aspect, ap- proaching more or less to all the preceding forms ; but most frequently they have the faces arranged either in six groups of eight, or eight of six, or twelve of four faces. There are twenty-four long edges, often corresponding to those of the /^^-A''' rhombic-dodecahedron ; twenty- y^^-^t^TT — ""^<;^\ intermediate edges lying in J^l \ / / \/i ^\n\ pairs over each edge of the in- ^f'''\rX~~}^\ — scribed octahedron ; andtwenty- VV^ X. '> I' lyf four short edges in pairs over n\ ~a4V^\ ' ' >V/ ^^^^ edges of the inscribed cube. There are six ditetragonal angles ^^^C/'/y^ joined by the principal axes, eight hexagonal and twelve Fig. 7, Hexakisoctahedroii. rhombic angles. — Ex., fluor spar, garnet, diamond. The seven forms of crystals now described are related to each other in the most intimate manner. This will ap- pear more distinctly from the following account of the derivation of the forms, with w^hich is conjoined an explana- tion of the crystallographic signs or symbols by which they are designated. We have adopted these symbols throughout this work, in the belief that they not only mark the forms in a greatly abbreviated manner, but also exhibit the rela- tions of the forms and combinations in away which words could hardly accomplish. The derivation of forms is that process by which, from one form chosen for the purpose, and considered as the type — ^the fundamental or primary form — all the other forms of a system may be produced, according to fixed principles or general laws. In order to understand this process or method of derivation, the student should keep in mind that the posi- tion of any plane is fixed when the positions of any three points in it, not all in one straight line, are known. To determine the position, therefore, of the face of a crystal, it is only necessary to know the distance of three points in it from the centre of the crystal, or the point in which the DERIVATION OF FORMS. 9 axes intersect each other. Usually the points in which the face or its supposed extension meets the three axes of the crystal are chosen, and the portion of the axes between these points and the centre are named parameters, and the position of the face is sufficiently known when the relative length or proportion of these parameters is ascertained. When the position of one face of a simple form is thus fixed or described, all the other faces are in like manner fixed, since they are all equal and similar, and have equal para- meters — that is, intersect the axes in a uniform manner. Hence the expression which marks or describes one face, marks and describes the whole figure, with all its faces. The octahedron is adopted as the primary or funda- mental form of the tesseral system, and distinguished by the first letter of the name, 0. Its faces cut the half- axes at equal distances from the centre ; so that these semi- axes, or the parameters of the faces^ have to each other the proportion 1:1:1. In order to derive the other forms from the octahedron, the following construction is employed. The numbers in brackets refer to the descrip- tions above. Suppose a plane so placed in each angle of the octahe- dron as to be vertical to the axis passing through that angle, and consequently parallel to the two other axes (or to cut them at an infinite distance = co) ; then the hexahedron or cube (1) is produced, designated by the crystallographic sign 00 0 00 ; expressing the proportion of the parameters of its faces, or oo : oo : 1. If a plane is supposed placed on each edge parallel to one axis, and cutting the two other axes at equal distances, the resulting figure is the rhombic- dodecahedron (3), designated by the sign ooO, the propor- tion of the parameters of its faces being oo : 1:1. The triakisoctahedron (5) arises when on each edge of the octa- hedron planes are placed cutting the axis not belonging to that edge at a distance from the centre m which is a rational number greater than 1. The proportion of its parameters is therefore m: 1 : 1, and its sign mO ; the most common varieties being fO, 20, and 30. When, on the other hand, from a similar distance m in each two semiaxes pro- 10 TESSEKAL SYSTEM. longed, a plane is drawn to the other semiaxis, or to each angle, an ikositetrahedron (6) is formed ; the parameters of its faces have consequently the proportion m\m \ 1, and its sign is mOm ; the most common varieties being 202 and 303, the former very frequent in leucite, analcime, and garnet. When, again, planes are drawn from each angle, or the end of one semiaxis of the octahedron, parallel to a second axis, and cutting the third at a distance % greater than 1, then the tetrakishexahedron (4) is formed, the parameter of its faces oo : 1 ; its sign odOti; and the most common varieties in nature ooOf, oo02, and oo03. Finally, if in each semiaxis of the octahedron two distances, m and be taken, each greater than 1, and m also greater than Uy and planes be drawn from each angle to these points, so that the two planes lying over each edge cut the second semiaxis belonging to that edge, at the smaller dis- tance and the third axis at the greater distance m, then the hexakisoctahedron (7) is produced, the parameters, which are m : n : 1, its sign mOn^ and the most common varieties 30f, 402, and 50f. It must be observed that the numbers in these signs refer to the parameters of the faces, not to the axes of the crystal, which are always equal. One parameter also is always assumed = 1, and then that either one only of the two other parameters marked by the number before 0, or both of them marked by the numbers before and after 0 may be changed, and in the proportion of these numbers. The forms of crystals now described are named EolO" hedral^ the whole faces of each form being seen on them. But there are other crystals which appear as if formed by one half the faces of these forms, which have increased so as to suppress the other half of the faces alternating with them. These are named Hemihedral, and occur both in this system and in all the others. These Hemihedral, or, as they are sometimes named in this system, Semitesseral, forms are : — (1.) The tetrahedron (Fig. 8), bounded by four equilateral triangles. It has six equal edges with faces meeting at 70° 32', and four trigonal angles. The principal axes join the HEMIHEDRAL FORMS. 11 middle points of each two opposite edges. — Ex., fahlore, boracite, and helvine. Fig. 8. Tetrahedron. Fig. 9. Trigonal-dodecahedron. (2.) The trigonal-dodecahedrons (Fig. 9) are bounded by twelve isosceles triangles, and vary in general form from the tetrahedron to the hexahedron. There are six longer edges corresponding to those of the inscribed tetrahedron, and twelve shorter, placed three and three over each of its faces ; and four hexagonal and four trigonal angles. — Ex., fahlore. (3.) The deltoid-dodecahedrons (Fig. 10) are bounded by twelve deltoids, and vary in general form from the tetra- hedron on the one hand, to the rhombic-dodecahedron on the other. They have twelve longer edges lying in pairs Fig. 10. Deltoid-dodecahedrons. Fig. 11. Hexakistetrahedron. over the edges of the inscribed tetrahedron j and twelve shorter edges, three and three over each of its faces. The angles are six tetragonal (rhombic), four acute trigonal, and four obtuse trigonal angles. The principal axes join two and two opposite rhombic angles. — Ex., fahlore. 12 TESSERAL SYSTEM. (4.) The hexakistetrahedrons (Fig. 11) are bounded by twenty-four scalene triangles, and most commonly have their faces grouped in four systems of six each. The edges are twelve shorter and twelve longer, lying in groups of three over each face of the inscribed tetrahedron, and twelve inter- mediate in pairs over its edges. The angles are six rhom- bic, joined in pairs by the principal axes, and four acuter and four obtuser hexagonal angles. — Ex., diamond. In these forms, often named tetrahedral, the faces are oblique to each other. Their derivation and signs are as fol- lows : — The tetrahedron arises when four alternate faces of the octahedron, two opposite above, and two intermediate below, are enlarged, so as to obliterate the other four, and its sign is hence ^ • But, as either four faces may be thus en- 2 larged or obliterated, two tetrahedrons can be formed similar in all respects except in position, and together making up the octahedron. These are distinguished by the signs + and — , added to the above symbol, but only the latter in general expressed thus — ~. In all hemihedric systems two forms similarly related occur, which may thus be named comple mentary forms. The trigonal dodecahedron is derived from the icositetrahedron by the expansion of the alternate tri- gonal groups of faces. Its sign is ^ , the most common 202 variety being -— — . The deltoid-dodecahedron is in like z manner the result of the increase of the alternate tris^onal groups of faces of the triakisoctahedron, and its sign is Lastly, the hexakistetrahedron arises in the development of alternate hexagonal groups of faces in the hexakisocta- hedron, and its sign is . Two semitesseral forms with parallel faces occur. (1.) The pentagonal dodecahedrons (Fig. 12) bounded by twelve symmetrical pentagons, and varying in general aspect HEMIHEDRAL FORMS. 13 between the hexahedron and rhombic-dodecahedron. They have six regular (and in general longer) edges, lying over the faces of the inscribed hexahedron, and twenty-four generally shorter (seldom longer) edges, usually lying in pairs over its edges. The angles are eight of three equal Fig. 12. Pentagonal-dodecahedrons. Fig. 13. Dyakisdodecahedron. angles, and twelve of three unequal angles. Each principal axis unites two opposite regular edges. This form is de- rived from the tetrakishexahedron, and its sign is one 2i oo 0 *^ of the most common varieties being-— ^, found frequently in iron pyrites and cobaltine. (2.) The dyakisdodecahedron (Fig. 1 3), bounded by twenty-four trapezoids with two sides equal, has twelve short, twelve long, and twenty-four inter- rig. 14. Pentagonal-dodecahedron. Fig. 15. Pentagonal-icositetrahedron. mediate edges. The angles are six equiangular rhombic, united in pairs by the principal axes, eight trigonal, and 14 TESSERAL SYSTEM. twenty-four irregular tetragonal angles. It is derived from the hexakisoctahedron, and its sign is j^^^^J, the brackets being used to distinguish it from the hexakistetrahedron, also derived from the same primary form. It occurs in iron pyrites and cobaltine. There are two other tetrahedral forms, the pentagonal dodecahedron (Fig. 14), and the pentagonal icositetrahedron (Fig. 15), both bounded by irregular pentagons, but not yet observed in nature. Combinations. — These forms of the tesseral system (and this is true also of the five other systems of crystallisation) not only occur singly, but often two, three, or more united in the same crystal, forming what are named combinations. In this case it is evident that no one of the individual forms can be complete, because the faces of one form must partially interfere with the faces of other forms. A combination therefore implies that the faces of one form shall appear symmetrically disposed between the faces of other forms, and consequently in the room of certain of their edges and angles. These edges and angles are thus, as it were, cut off, and new ones produced in their place, which properly belong neither to the one form nor the other, but are edges or angles of combination. Usually, one form predominates more than the others, or has more influence on the general aspect of the crystal, and hence is distinguished as the pre- dominant form, the others being named subordinate. The following terms used on this subject require explanation. A combination is developed when all the forms contributing to its formation are pointed out; and its sign consists of the signs of these forms, written in the order of their in- fluence on the combination, with a point between. An angle or edge is said to be replaced when it is cut off by one or more secondary planes ; it is truncated when cut by one plane, forming equal angles with the adjacent faces ; and an edge is bevelled when replaced by two planes, which are equally inclined to the adjacent faces. It will be readily seen that such combinations may be exceedingly numerous, or rather infinite ; and only a few of the more common can be noticed, simply as specimens COMBINATIONS. 15 of the class. Many others more complicated will occur in the descriptive part of this treatise. Among holohedral combinations, the cube, octahedron, and also the rhombic- dodecahedron, are the predominant forms. In Fig. 16 the \ Fig. 16. Combination : Hexahedron and Oetaliedron. Fig. 17. Octahedron and Hexahedron. cube has its angles replaced by the faces of the octahedron, and the sign of this combination is oc 0 oo . 0. In Fig. 1 7 this process may be regarded as having proceeded still far- ther, so that the faces of the octahedron now predominate, and the sign, of the same two elements but in reverse order, is 0 . GoOco . In Fig. 18 the cube has its edges replaced Fig. 18. by the faces of the rhombic-dodecahedron, the sign being ooOgo . coO ; whilst in Fig. 19 there is the same combina"^ tion, but with the faces of the cube subordinate, and hence the sign is goO . ooO(X) . The former figure, it will be seen, has more the general aspect of the cube ; the latter of the dodecahedron. In combinations of semitesseral forms with oblique faces, 16 TESSERAL SYSTEM. the tetrahedron, the rhombic-dodecahedron, or even the hexahedron, seldomer a trigonal-dodecahedron, are the more Fig. 20. Fig. 21. common predominant forms. In Fig. 20 two tetrahedrons in opposite positions, ^ .- ^, are combined. In Fig. 21 a very complex combination of seven forms is represented in a crystal of fahlore, its full sign being — . ocOoo (/) . cOio) . ^(P). - ^^(r).l^(«') . cc03(s) ; the letters in brackets connecting them with the respective faces of the figure. As examples of combinations of semi- Fi'^ 22. Fiff. 23. tesseral forms with parallel faces, we may take Fig. 22, in which each of the angles of the cube is unsymmetrically replaced by three faces of the dyakisdodecahedron, and hence ocOoo . j^^^J ^ ^^S- ^3, in which the pentagonal- TETKAGONAL SYSTEM. 17 dodecahedron has its trigonal angles replaced by the faces of the octahedron, consequently with the sign 0. 2 Figure 24 represents the same combination but with greater predominance of the faces of the octa- hedron, the crystal being bounded by eight equilateral and twelve isosceles triangles. In interpreting a combination it should be observed that the faces of each form are all similar. When in a combination, therefore, there are only 4 faces similar to each other, they belong to the tetrahedron ; if only 6, to the hexahedron ; if only 8, to the octahedron ; if only 12 parallel, to the rhombic or pentagonal dodeca- hedron; and if 12 not parallel, to the trigonal or deltoid dodecahedron. In the following systems there is always one axis un- equal to (longer or shorter than) the others. This is placed vertical and named the chief axis ; its ends are poles, and the edges connected with them polar edges. The other axes are named subordinate or lateral axes, and the plane that passes through them is the base. A plane through the chief and a lateral axis is a normal chief section. In these systems also the three following forms occur: — 1st, Pyra- mids, of which the faces are triangles, and each composed of two geometric pyramids placed base to base, and named closed forms, as the crystals are shut in by definite faces on every side. 2d, Prisms bounded by plain faces parallel to one axis. They are thus of unlimited extent in the direction of that axis, and therefore named open fovrus, but in crystals are shut in by faces of other forms. 3d, Pina- coids or Tables — two faces intersecting one axis and parallel to the others, and thus also open forms, or unlimited in the direction of these axes. 11. Tetragonal System. — This system has three axes at right angles, two of them equal, and one, the chief axis, unequal. The name tetragonal is derived from the form of c 18 TETRAGONAL SYSTEM. There are eight the basis, which is usually quadratic, tetragonal forms, of which five are closed. (1.) Tetragonal pyramids (Figs. 25, 26) are inclosed by eight isosceles triangles, with four middle edges all in one Tetragonal Pyramids Fig. 25. Obtuse. Fig. 26. Acute. plane, and eight polar edges. There are three kinds of this form, distinguished by the position of the lateral axes. In the first these axes unite the opposite angles ; in the second they intersect the middle edges equally ; and in the third Fig. 27. Ditetragonal Pyramid. Fig. 28. Tetragonal Sphenoids. tliey lie in an intermediate position, or divide tliese edges unequally ; the latter being lienuhedral forms. These pyra- mids are" also distinguished as obtuse (Fig. 25) or acute (Jig. FORMS OF CRYSTALS. 19 26), according as the vertical angle is greater or less than in the octahedron, which, though intermediate, is never a tetragonal form. (2.) Ditetragonal pyramids (Fig. 27) are bounded by sixteen scalene triangles, whose base-lines are all in one plane. This form rarely occurs except in combi- nations. (3.) Tetragonal sphenoids (Fig. 28), bounded by four isosceles triangles, are the hemihedral forms of the first variety of tetragonal pyramids. (4.) The tetragonal scaleno- hedron (Fig. 29), bounded by eight scalene triangles, whose bases rise and fall in a zigzag line, is the hemihedral form of the ditetragonal pyramid. The latter two forms are rare. Open forms, — (1.) Tetragonal prisms (Fig. 30), bounded by four planes parallel to the principal axis ; (2.) ditetragonal prisms by eight similar planes ; and (3.) the basal pinacoid, consisting merely of two parallel faces bounding the prisms at the ends above and below. The various series of tetragonal crystals are distinguished from each other only by their relative dimensions. To determine these, one of the series must be chosen as the primary form, and for this purpose a tetragonal pyramid of the first variety, designated by P as its sign, is selected. The angle of one of its edges, especially the middle edge, found by measurement, determines its angular dimensions ; whilst the proportion of the principal axis {a) to the lateral axes sup- posed equal to 1, gives its linear dimensions. The parameters, therefore, of each face of the fundamental form are 1 : 1 : a. Fig. 29. Tetragonal Scalenohedron. Fig. 30. Tetragonal Prism. 20 TETRAGONAL SYSTEM. Now if m be any (rational) number, either less or greater than one, and if from any distance ma in the prmcipal axis planes be drawn to the middle edge of P, then new tetra- gonal pyramids of the first kind, but more or less acute or obtuse than P, are formed. The general sign of these pyra- mids is mP, and the most common varieties ^P, 2P, ii-, with the chief axis equal to \, twice or thrice that oi P. ^ It m becomes infinite, or = , a tetragonal pyramid ot the secokd'kind arises, designated generally by mPoo the niost common in the mineral kingdom being Pco and 2Pco . ihe relation of these to pyramids of the first kind is shown m Pig 31 where ABBBX is the first, and ACCCX the second kind of pyramid. In like manner from the prism ooP, is ooPco . COMBINATIONS. 21 The combinations of the tetragonal system are either holohedral or hemihedral ; but the latter are rare. Prisms and pinacoids must always be terminated on the open sides by other forms. Thus in Fig. 32 a square prism of the first kind is terminated by the primary pyramid, and has its lateral angles again replaced by another more acute pyra- mid of the second kind, so that its sign is ooP . P . 2Poo . Fig. 33. Fig. 34. In Fig. 33 a prism of the second kind is first bounded by the fundamental pyramid, and then has its edges of combi- nation replaced by a ditetragonal pyramid, and its sign is here ooPoo . P . 3P3. In Fig. 34 the polar edges of the pyramid are replaced by another pyramid, its sign being P . Poo . In Fig. 35 a hemihedric form very characteristic of chalcopyrite is represented, P and P' being the two sphenoids, a the basal pinacoid, and 5, c, two ditetra- gonal pyramids. III. The Hexagonal System. — The essential character of this system is, that it has four axes — three equal lateral axes intersecting each other in one plane at 60°, and one prin- cipal axis at right angles to them. The plane through the lateral axes or the basis, from its hexagonal form gives the name to the system. As in the last system, its forms are Fig. 35. 22 HEXAGONAL SYSTEM. either closed or open ; and are divided into holohedral, hemihedral, and tetartohedral— the last forms with only a fourth part of their faces developed. Many of the latter forms are rare, and only a few of the more common require to he here described. The hexagonal pyramids (Figs. 36, 37) are bounded by twelve isosceles triangles, and are of three kinds, accordmg as the lateral axes fall in the angles, in the middle of the lateral edges, or in another point of these edges, the latter being hemihedral forms. They are also classed as acute or obtuse, but without any very precise limits. The trigonal Fig. 86. Eig. 37. pyramid is bounded by six triangles, and may be viewed as the hemihedral form of the hexagonal. The dihexagonal pyramid is bounded by twenty-four scalene triangles, but has never been observed alone, and rarely even in combinations. The more common prisms are the hexagonal of six sides, and the dihexagonal of twelve sides. As the fundamental form of this system a particular pyramid P is chosen, and its dimensions determined either from the proportion of the lateral to the principal axis (1 : a), or from the measurement of its angles. From this form (mP) others are derived exactly as in the tetragonal system. Thus dihexagonal pyramids are produced with the general sign mP?i, the chief pecuHarity being that, whereas COMBINATIONS. 23 in the tetragonal system n might have any rational value from 1 to 00, in the hexagonal system it can only vary from 1 to 2, in consequence of the geometric character of the figure. When n-2 the dihexagonal changes into a hexa- gonal pyramid of the second kind, whose sign is mP2. When m is = 00 various, prisms arise from similar changes in the value of n ; and when m = 0 the basal pinacoid. Few hexagonal mineral species form perfect holohedral combinations. Though quartz and apatite appear as such, yet properly the former is a tetartohedral, the latter a hemihedral species. In holohedral species the predominant faces are usually those of the two hexagonal prisms ooP and 00 P2, or of the pinacoid OP ; whilst the pyramids P and 2P2, are the most common subordinate forms. Figure 38 represents the prism, bounded on the extremities by two pyramids ; one, P, forming the point, the other 2P2 the rhombic faces on the angles, or ooP . P . 2P2. In some crystals the lateral edges of the prism are replaced by the Fig. 38. Fig. 39. second prism ooP2, producing an equiangular twelve-sided prism, which always represents the combination ooP . ooP2, and cannot occur as a simple form. An example of a more complicated combination is seen in Fig. 39, of a crystal of apatite, whose sign with the corresponding letters is 00 P(ilf) . 00 V2{e) . OP(P) . iP(r) . V{x) . 2P(^) . P2(a) . . 2P2(s) . 4P2(^^). 24 HEXAGONAL SYSTEM. Hexagonal minerals more frequently crystallise in those series of hemihedral forms that are named rhombohedral, from the prevalence in them of rhombohedrons. These are (Fig. 40) bounded by six rhombs, whose lateral edges Fig. 40. Rhombohedrous. do not lie in one plane, but rise and fall in a zig-zag manner. The principal axis unites the two trigonal angles, formed by three equal plane angles, and in the most common variety the secondary axes join the middle points of two opposite edges. When the polar edges form an angle of more than 90° the rhombohedrons are named obtuse ; when of less, acute. Hexagonal scalenohedrons (Fig. 41) are bounded by twelve scalene triangles, whose lateral edges do not lie in one plane. The principal axis joins the two hexagonal angles, and the secondary axis the middle points of two opposite lateral edges. The rhombohedron is derived from the first kind of hexagonal pyramid by the hemihedral development of its alternate faces. Its general sign should therefore be ^. — ; but on several grounds it is found Fig. 41. 2 scaienohedron. ^^^^^^ designate it by R or mE, and its complimentary figure by -mR. When the prism or pinacoid arise as its limiting forms, they are designated by ooR and OR, though in no respect changed from the limiting forms ooP and OP of the pyramid. The scaieno- hedron is properly the hemihedral form of the dihexagonal EHOMBOHEDRAL FORMS. 25 pyramid, but is better derived from the inscribed rhombo- hedron mE. If the halves of the principal axis of this are multiplied by a definite number ,v and then planes drawn from the extremities of this enlarged axis to the lateral edges of the rhombohedron, as in Figure 42, the scalenohedron is constructed. It is now designated by mRn (the n on the right though referring to the chief axis) and the dihex- agonal prism in this series by GoR?2 (formerly m& and ooR^). The combinations of rhombo- hedral forms are very numerous, some hundreds being described in calc-spar alone. Among the more common is the prism in combination with a rhombohe- dron, as in the twin crystal of calc-spar (Fig. 43), with the sign 00 R . -|R, the lower half being the same form with the upper, but turned round 180°. In Fig. 44, the rhombohedron mR has its polar edges replaced by Fig. 42. Fig. 43. Fig. 44. another rhombohedron — ^mR ; and in Fig. 45 its lateral 26 EHOMBIC SYSTEM. edges bevelled by the scalenohedron mRn. A more com- plex combination of five forms is represented in the crystal of calc-spar, Fig. 46, its sign with the letters on the faces being E5(?/) . E3(r) . E(P) . 4E(m) . ooE(c). Tetartohedral combinations are seen most distinctly in pure quartz or rock-crystal. Fig. 45. Fig. 46. IV. Rhombic System. — The rhombic system is character- ised by three axes, all unequal, but at right angles to each Fig. 47. Fig. 48. other. Any one of these may be assumed as the chief axis, when the others are named subordinate. The plane pass- ing through the secondary axes or the basis forms a rhomb. FORMS. 27 and from this the name is derived. This system comprises only a few varieties of forms that are essentially distinct, and its relations are consequently very simple. The closed forms are — {1st.) The rhombic pyramids (Figs. 47, 48), bounded by eight scalene triangles, whose lateral edges lie in one plane, and form a rhomb. They have eight polar edges — four acute and four more obtuse — and four lateral edges, and six rhombic angles, the most acute at the extremities of the longest axis. (2d.) The rhombic sphenoids (Fig. 49) are bounded by four scalene triangles with their lateral edges not in one plane; and are a hemihedral form of the rhombic pyramid of unfrequent occurrence. The open forms again are, (3d.) Rhombic prisms bounded by four planes parallel to one of the axes which is indefinitely extended. They are divided into up- right and horizontal prisms, according as either the principal or one of the lateral axes is supposed to become infinite. For the latter form the name doma or dome has been used ; and two kinds, the macrodome and the brachydome, have been distinguished. Rhombic pinacoids also arise when one axis becomes ==0, and the two others are indefinitely ex- tended. In deriving these forms from a primary, a particular rhombic pyramid P is chosen, and its dimensions determined either from the angular measurement of two of its edges, or by the linear proportion of its axes a : b : c ; the greater lateral axis b being assumed equal to 1. To the greater lateral axis the name macrodiagonal is frequently given ; to the shorter, that of brachydiagonal ; and the two principal sections are in like manner named macrodiagonal and brachydiagonal, according to the axis they intersect. The same terms are applied throughout all the derived forms, where they consequently mark only the position of the faces Fig. 49. Rhombic sphenoids. 28 EHOMBIC SYSTEM. in respect to the axes of the fundamental crystal, without reference to the relative magnitude of the derived axes. By multiplying the principal axis by any rational num- ber m, greater or less than 1, a series of pyramids arise, whose general sign is mP, and their limits the prism and pinacoid, the whole series being contained in this formula, QP p mP ooP ; which is the funda- mental series, the lateral axes always remaining unchanged. From each member a new series may, how- ever, be developed in two directions by in- creasing one or other of the lateral axes. When the macrodiagonal is thus multiphed by any number n greater than 1, and planes drawn from the distance n to the polar edges, a new pyramid is produced, named a macropyramid, with the sign 7nPn, the mark over the P point- ing out the axis en- larged. When n — CO a macrodome results, with the sign mPoo . If the shorter axis is multiplied, thenbrachy- pyramids and brachy- domes are produced with the signs mfn and ?7iPoo . So also from the prism ooP, on the one side, numerous macroprisms ooPtz, with the limiting macropinacoid ocPoc ; on the other, numerous brachyprisms ooPt^, with the limit form odPoo, or the brachypinacoid. In Figs. 50, 51, the two domes are shown in their relation to the primitive pyramid. The pyramids seldom occur independent, or even as the Fig. 60. Macrodome. Fig. 51. Brachydome. COMBINATIONS. 29 predominant forms in a combination — sulphur, however, being an exception. Prisms or pinacoids usually give the M Fig. 52. Fig. 53. Fig. 54. Fig. 55. general character to the crystal, which then appears either in a columnar or tabular, or even in a rectangular pyramidal form. The determination of the position of these crystals, as vertical or horizontal, depends on the choice of the chief axis of the funda- mental form. In the topaz crystal (Fig. 52) the brachyprism and the pyramid are the predomi- nant elements, associated with the prism, its sign and letters being ocP2(/) . P(o) . ooP(w). Fig. 53 of stilbite is an other example, the macropinacoid ooPco or M, being combined with the pyramid P(r), the brachy- pinacoid ooPoo (T), and the basal pinacoid OP (P). An- other instance is Fig. 54 of a lievrite crystal, where the brachyprism and pyramid combine with the macrodome, or G0P2.P.P00. The above figures are very common forms of barytes ; Figs. 55 and 56 being both composed Fig. 56. 30 MONOCLINIC SYSTEM. of the pinacoid, a brachydome and macrodome, with sign OP (c) . P 00 (/) |P co(d), the variation in aspect arising from the predominance of different faces ; and Fig. 57 consisting of the mac- rodome |Poo , the prism 00 P (g)j and the pinacoid V. The Monodimc System. — This system is characterised by three unequal axes, two of which intersect each other at an obhque angle, and are cut by the third at right angles. One of the oblique axes is chosen as the chief axis, and the other axes are then distinguished as the orthodiagonal (right- angled), and clinodiagonal (oblique-angled). The same terms are applied to the chief sections, and the name of the system refers to the fact that these two planes and the base, to- gether with two right angles, form also one oblique angle (7. The forms of this system approach very near to those of the rhombic series, but the inclination of the axes, even when almost a right angle, gives them a peculiar character, by which they are always readily distinguished. Each pyra- mid thus separates into two altogether independent forms or hemipyramids. Three varieties of prism also occur — ver- tical, inclined, and horizontal — with faces parallel to the chief axis, the clinodiagonal or the orthodiagonal. The hori- zontal prisms, like the pyra- mids, separate into two inde- pendent partial forms, named hemiprisms or hemidomes. The inclined prisms are often designated clinodomes, the term prism being restricted to the vertical forms. Orthopina- coids and clinopinacoids are also distinguished from their position in relation to the axes. The monoclinic p} ramids (Fig. 58) are bounded by eight / -V Fig. 58. Monoclinic pyramid. FOKMS. 31 scalene triangles of two kinds, four and four only being similar. Their lateral edges lie all in one plane, and the similar triangles are placed in pairs on the clinodiagonal polar edges. The two pairs in the acute angle between the orthodiagonal and basal section are designated the positive hemipyramid ; whilst the two pairs in the obtuse angles of the same sections form together the negative hemipyramid. But as these hemipyramids are wholly independent of each other, they are rarely observed combined. More frequently each occurs alone, and then forms a prism-like figure, with faces parallel to the polar edges, and open at the extremities. Hence, like all prisms, they can only appear in combination with other forms. The vertical prisms are bounded by four equal faces parallel to the principal axis, and the cross section is a rhomb ; the clinodomes have a similar form and section ; whilst the horizontal prisms or domes have unequal faces, and their section is a rhomboid. The mode of derivation of these forms closely resembles that of the rhombic series. A complete pyramid is assumed as the fundamental form, and designated =±= P, in order to express the two portions of which it consists. Its dimen- sions are given when the proportion of its axes a:h : and the angular inclination of the oblique axes C, which is also that of the orthodiagonal section to the basis, are known. The fundamental series of forms is, OP =t mP =t P ± mP 00 P ; from each of whose members, by changing the dimensions of the other axes, new forms may be again derived. Thus from ± mV, by multiplying the orthodiagonal by any number a series of orthopyramids ± m?''n is produced, with the orthodomes mP^'oo as limiting forms. The clinodiagonal produces a similar series of chno- pyramids ± m?% with the limiting clinodome mP'^oo always completely formed, and therefore without the signs =t attached. From ooP arise orthoprisms and the orthopinacoid ccP^co , and clinoprisms ooV\ and the cHno- pinacoid oo P'go . In these signs the o or c attached to the P indicates that the orthodiagonal or clinodiagonal axis has been multiplied. Formerly the latter forms were enclosed in brackets, thus (mPoo ) = mP^oo . The combinations of this system may be easily under- 32 MONOCLINIC SYSTEM. stood from their resemblance to those of the rhombic ; the chief difficulty being in the occurrence of partial forms, which, however, closely resemble the hemihedral forms of the previous systems. We shall therefore only select a few examples frequently observed in the mineral kingdom. Fig. 59. Fig. 60. Fig. 59 represents a very common form of gypsum crystals ooP'oo . (P) . ooP(/) . P(&). The most common form of augite is represented in Fig. 60, with the sign ooP(m) . ooP^oo (r) . ooP^oo (/) . P(s). Fig. 61 is a crystal of com- mon felspar or orthoclase, composed of the clinopinacoid Fig. 61. Fig. G2. odP'oo (71/), the prism a)P (T), the basal pinacoid OP(P), and the hemidomcs 2P^oo (//) : to which, in Fig. 62 of the same mineral, the hcmipyramid P(o), and the clinodome 2P'oo {n) are added. TKICLINIC SYSTEM. 33 VI. Triclinic System. — This is the least regular system, and departs the most widely from symmetry of form. The axes are all unequal, and inclined at angles none of which are right angles, so that to determine any crystal, or series of forms, the proportion of the axes a:h : c, and also their angles, or those of the inclination of the chief sections, must be known. As in the previous system, one axis is chosen as the principal axis, and the two others distinguished as the macrodiagonal and brachydiagonal axes. In consequence of the oblique position of the principal sections, this system consists entirely of partial forms wholly independent on each other, and each composed only of two parallel faces. The complete pyramid is thus broken up into four distinct quarter pyramids and the prism into two hemiprisms. Each of these partial forms is thus nothing more than a pair of parallel planes, and the various forms consequently mere individual faces. This circumstance renders many triclinic crystals very unsymmetrical in appearance. Triclinic pyramids (Fig. 63) are bounded by eight triangles whose lateral edges lie in one plane. They are equal and parallel two and two to each other ; each pair forming, as just stated, a tetartopyramid or open form, only limited by combination with other forms, or, as we may suppose, by the chief sections. The prisms are again either vertical or inclined ; the latter named domes, and their section is always rhomboidal. In deriving the forms, the fundamental pyramid is placed upright with its brachydiagonal axis to the spectator, and the partial forms designated, the two upper by 'P and P', the two lower by ^P and P^, as in the figure. The further derivation now follows as in the rhombic system, with the modifications already mentioned, so that we need not delay on it longer, especially as the minerals crystallising in these forms are not numerous. Triclinic pyramid. 34 TRICLINIC SYSTEM. Some combinations of this system, as the series exhibited by most of the felspars, approach very near to the mono- clinic system ; whilst others, as cyanose or blue vitriol and axinite, show great incompleteness and want of symmetry. In the latter case the determination of the forms is often difficult and requires great attention. As specimens, we may notice the albite crystal (Fig. 64), in which P is the basal M Fig. 64. pinacoid OP ; M the brachy diagonal pinacoid ooPoo ; 5 the upper right pyramid P' ; I the right hemiprism oo P' ; T the left hemiprism oo'P, and x the hemidome 'P'oo . Figures 65 and 66 are crystals of axinite, the former from Dauphine, the latter common in Cornwall, of whose faces_the following is the development : — r the macropinacoid ooPco ; P the left hemiprism ooT 3 u the left upper quarter pyramid T ; / the left upper quarter pyramid 2T ; s the left upper partial form of the macropyramid 3T3, and x the hemidome 2T' qo . IMPEEFECTIONS OF CRYSTALS. 35 Imjperfections of Crystals. In the foregoing description of the forms of crystals the planes have been supposed smooth and even, the faces equal and uniform, or at the same distance from the centre or point of intersection of the axes, and each crystal also perfect or fully formed and complete on every side. In nature, how- ever, these conditions are rarely if ever realised, and the edges of crystals are seldom straight lines, or the faces mathematical plane surfaces. A very interesting variety of these irregularities, which pervades all the systems ex- cept the tesseral, is named hemimorphism. In this the crystals are bounded at the opposite ends of their chief axis by faces belonging to distinct forms, and hence only the upper or under half of each form is produced, or the crystal, as the name implies, is half-formed. Figure 67 represents Fig. 67. I Fig. 68. a common variety of tourmaline, bounded on the upper end by the planes of the rhombohedrons E and - 2R, and on the lower end by the basal pinacoid. In Fig. 68 of galmei the upper extremity shows the basis two brachydomes o and p ; and two macrodomes m and I ; whilst on the lower end it is bounded by the faces P of the primary form. This appearance becomes more interesting from the fact that many hemimorphic crystals acquire polar electricity from heat — that is, exhibit opposite kinds of electricity at opposite ends of the crystal. 36 IRKEGULARITY OF FORMS. The faces of crystals are very frequently rendered im- perfect by strice or minute linear and parallel elevations and depressions. These arise in the oscillatory combination of two crystal forms, alternately prevailing through small spaces. The striae, therefore, are in reality the edges of combined forms. They are very common on quartz, shorl, and some other minerals ; and frequently indicate combina- tions where only a simple form would otherwise appear to exist. The cubes and pentagonal dodecahedrons of iron pyrites are frequently striated, and in three directions at right angles to each other. In calc-spar the faces of the rhombohedron, — JR (g in Fig. 43 above), are almost never without striae parallel to the oblique diagonal. The stria- tion is said to be simple when only one series of parallel lines appears on each face, or feathered when two systems diverge from a common line. In other crystals the faces, then said to be dimsy, are covered by numerous projecting angles of smaller crystals ; an imperfection often seen in fluor spar. The faces of crystals occasionally appear curved either as in tourmaline and beryl from the peculiar oscilla- tory combination mentioned, or by the union of several crystals at obtuse angles, like stones in a vault, as in stilbite and prehnite. A true curvature of the faces probably oc- curs in the saddle-shaped rhombohedrons of dolomite and siderite, in the lens-like crystals of gypsum, and in the cur- ved faces so common on diamond crystals. In chabasite similar curved faces occur, but concave. In galena and augite the crystals are often rounded on the corners, as if by an incipient state of fusion. On other crystals the faces are rendered uneven from inequalities following no certain rule. These imperfections furnish valuable assistance in develop- ing very complex combinations, all the faces of each indi- vidual form being distinguished by the same peculiarity of surface. Irregularities in the forms of crystals are produced when the corresponding faces are placed at unequal distances from the centre, and consequently differ in form and size. Thus the cubes and octahedrons of iron pyrites, galena, and fluor spar, are often lengthened along one axis. Quartz is subject CONSTANCY OF ANGLES. 37 to many such irregularities, which are seen in a very remark- able manner on the beautiful transparent and sharply angular crystals from Dauphin^. In such irregular forms, instead of one line, the axes are then represented by an in- finite number of lines, parallel to the ideal axis of the figure. The same irregularity carried to a greater extent frequently causes certain faces, required for the symmetry of the form, altogether to disappear. Again, some crystals do not fill the space marked out by their outline, holes and vacancies being left in the faces, occasionally to such an extent that they seem little more than mere skeletons. This appear- ance is very common on crystals produced artificially, as in common salt, alum, bismuth, silver, etc. A perfect crystal can only be produced when during its formation it is com- pletely isolated, so as to have full room to expand on every side. Hence the most perfect crystals have been originally imbedded singly in some uniform rock mass. Next to them in perfection are forms that grow singly on the surface of some mass of similar or distinct composition, especially when the point of adherence is small. An incompleteness of form, or at least a difficulty in determining it, arises from the minuteness of some crystals, or from their contracted dimen- sions in certain directions. Thus some appear mere tabular or lamellar planes, whilst others run out into acicular, needle- shaped, or capillary crystals. Amid all these modifications of the general form of the crystal, of the condition and aspect of its individual faces, or of its linear dimensions, one important element, the angular measurement, remains con- stant. In some crystals, indeed, increase of temperature produces an unequal expansion in diff'erent directions, slightly changing the relative inclination of the faces, but so small as to be scarcely perceptible in common measurements, and hence producing no ambiguity. More important are the angular changes which in many species accompany slight changes in chemical composition, particularly in the relative proportions of certain isomorphous elements. But notwith- standing these limitations, the great truth of the permanence of the angular dimensions of crystals, announced by Kom6 de risle, remains unaffected ; only, as Mohs well states, it 38 GONIOMETER. must not be interpreted with a rigid immutability, incon- sistent with the whole analogy of other parts of nature. The Goniometer and Measurement of Crystals, The fact just stated of the permanence of the angular dimensions of crystals shows the importance of some accu- rate method of measuring their angles ; that is the inclina- tion of two faces to each other. Two instruments have been specially used for this purpose, — the common or con- tact goniometer, invented by Caringeau, and the reflecting goniometer of Wollaston. The former is simply two brass rulers turning on a common centre, between which the crystal is so placed that its faces coincide with the edges of the rulers, and the angle is* then measured on a graduated arc. This instrument is sufficiently accurate for many purposes and for large crystals ; but for precise determination is far inferior to the reflecting goniometer. This requires smooth and even faces, but these may be very small, even the hundredth of an inch, in skilful hands ; and as small crystals are gener- ally most perfect, far greater accuracy can be attained, and the measurement de- pended on to one minute (1'). The reflecting goniometer is represented in the annexed figure. It consists essentially of a graduated circle mm, divided on its edge into twice 180°, or more often into half- rig. 69. Goniometer. MEASUREMENT OF CRYSTALS. 39 degrees, the minutes being read off by the vernier hh This circle turns on an axis connected with U, so that by turning this the circle is moved round, but is stopped at 180°, when moving in one direction, by a spring at k The other part of the instrument is intended to attach and adjust the crystal to be measured. The first axis of mm is hollow, and a second axis, aa, passes through it from 5S, so that this and all the connected parts from h to f can be turned with- out moving the circle mm. The axis d passes through a hole in he, so that it can turn the arm de into any required position ; / is a similar axis turning the arm og ; and a fourth axis, in like manner movable in ^, and with a small knob at ^, to which the crystal to be measured is attached. When about to use the instrument it should be placed on a table, with its base horizontal, which is readily done by the screws in it, and opposite to a window at about 1 2 or 15 feet distance, so that its axis shall be parallel to the horizontal bars of the window. One of the upper bars of the window, and also the lower bar, or, instead of the latter, a white line on the floor or table parallel to the window, should then be chosen in order to adjust the crystal. The observer places himself behind the instrument with the side a at his right hand. The crystal is then attached to 3' by a piece of wax with the two faces to be measured upwards. The axis fo is made parallel to aa, and the eye being brought near to the first face of the crystal, the axes aa and p are turned till the image of the window is seen reflected in the face with the horizontal and vertical bars in their position. The axis d is then turned through a considerable angle (say 60°), and the image of the window again sought and brought into its proper place by turning the axis /, without moving p. When this is done that face is brought into its true posi- tion, normal to d^ so that no motion of d can disarrange it. Hence the image of the window may now be sought in the second face and brought into its true position, with the hori- zontal bars seen horizontal, by moving the axes d and a. When this is done the crystal is properly adjusted, and the angle is thus measured. First bring the zero of the circle and vernier to coincide, and then turn the inner axis a or 40 MEASUREMENT OF CRYSTALS. ss, and move the eye till the image of the upper bar of the window reflected from the more distant face of the crystal coincides with the lower bar or horizontal line seen directly. Keeping the eye in its place, turn the outer axis U till the reflected image of the upper bar in the other face in like manner coincides with the lower line, and the angle of the two faces is then read off on the divided circle. As the angle measured is not directly that of the faces, but of the rays of light reflected from them, or the diff"erence of the angle wanted from 180°, the circle has the degrees numbered in the reverse direction, so as to give the angle without the trouble of subtracting the one from the other. The above apparatus for adjusting the crystal is an im- provement suggested by Naumann. In the original instru- ment the axis fo was made to push in or out in a sheath, and had a small brass plate, bent at right angles, inserted in a cleft at o, to which the crystal was attached. The crys- tal was adjusted, as formerly, by moving the plate, or the axis fo, and by slight motion of the arm de, which should be at right angles nearly to be when used. A considerable improvement is, to have a small mirror fixed on the stand below the crystal, with its face parallel to the axis aa, and in- clined at 45° to the window, when the lower line can be dis- pensed with, and the instrument used for various other pur- poses of angular measurement. Many alterations have been suggested for the purpose of insuring greater accuracy ; but the simple instrument is sufiicient for all purposes of deter- minative mineralogy, and the error from the instrument will in most cases be less than the actual variations in the dimen- sions of the crystals. Greater simplicity is indeed rather desirable, and the student will often find it sufiicient to attach the crystal by a piece of wax to the axis a directly, and give it the furthur adjustment by the hand. The only use of the parts from Z> to ^ is to enable the observer to place the crystal properly ; that is, with the edge to be measured parallel to the axis of the instrument, and as nearly as pos- sible coinciding with its centre. This is eff'ected when the reflection of the horizontal bar in the two faces appears parallel to that edge. MACLES. 41 Macles or Twin Crystals. When two similar crystals are united with all their similar faces and axes parallel, the one is merely a con- tinuation or enlargement of the other, and every crystal may be regarded as thus built up of a number of smaller crystals. Where, however, crystals are united with only some, not all, their similar faces and axes parallel, they are named macles or twin crystals. There are two kinds of macles, the first with the axes of the separate crystals parallel ; the second with these axes inclined or oblique. The first only occur in hemihedral forms, and the two crystals are then combined in the exact position i in which they would be de- rived from or reproduce the primary holohedral form. The second class, with oblique axes, occur both in holohedral and hemihedral forms, and the two individuals are placed in perfect symmetry to each other, in reference to a parti- cular face of the crystal which forms the plane of union or the equator of the made. We may also suppose the two crystals originally parallel, and the one turned round the normal of the united faces by 180°, whilst the other is stationary. Or we may suppose a crystal cut into halves in a particular direction, and one-half turned 180° on the other j and hence the name of hemitrope given to them by Hauy. The position of the two individuals in this case cor- responds with that of an object and its image in a mirror, whose surface then represents the plane of union. The manner in which the crystals unite also differs. Some are merely opposed, or the faces of union in simple contact ; others are, as it were, grown together, and mutu- ally interpenetrate, occasionally so completely as to appear like one individual. The twin edges and angles in which the two unite are often re-entering ; or the faces may coincide in one plane, when the line of union is either imperceptible, or is only marked by the meeting of two systems of striae, or other diversity in the physical characters of the two faces. The formation of twin crystals may be again repeated, forming groups of three, four, or more. When the planes 42 MACLES — TESSERAL. of union are parallel to each other, the crystals form rows of indeterminate extent ; where they are not parallel, they may return into each other in circles, or form bouquet-like or other groups. Where crystals are merely in juxtaposition, they are sometimes much shortened in the direction of the twin axis ; and where many occur in a series with parallel position, are often compressed into very thin plates, fre- quently not thicker than paper, giving to the surface of the aggregate a peculiar striated aspect. Only a few twin crystals in the different systems can Fig. 70. Fig. n. be noticed, chiefly as examples of this mode of formation. In the tesseral system forms that unite with parallel axes produce intersecting macles like the pentagonal dodeca- Fig. 72. Fig. 73. hedrons of iron pyrites in Fig. 70, and the tetrahedrons of fahlore in Fig. 7 1 , a similar formation also occurring in the TETRAGONAL. 43 diamond. In macles with inclined axes the two forms almost always unite by a face of the octahedron, and the two individuals are then generally apposed and shortened in the direction of the twin axis by one-half, so that they appear like a crystal that has been divided by a plane parallel to one of its faces, and the two halves >A^ turned round on each other by an angle of 1 80°. In this manner two /-y ^^"\..pX octahedrons of the spinel, magnetite jP<\~^^^^~)A^^^ automolite (Fig. 72), are frequently A V / p \\\ united. The same law prevails in \ \ \ \yf the intersecting cubes of fluor spar, \pA / \/y iron pyrites, and galena, represented \ in Fig. 73. In Fig. 74 of blende two rhombic dodecahedrons are fiTtT united by a face of the octahedron. In the tetragonal system twin crystals with parallel axes rarely occur, but are seen in chalcopyrite, and one or two other minerals. Where the axes are inclined the plane of union is very often one of the faces of the pyramid Poo , or one of those faces that would regularly replace the polar edges of the fundamental form P. The crystals of tin ore obey this law, as seen in Fig. 75, where the individuals are pyramidal, and in the knee-shaped crystal (Fig. 76), where they are more prismatic. Hausmanite appears like Fig. 77, in which the fundamental pyramid P prevails, on whose Fig. 75. Fig. 76. 44 MACLES — HEXAGONAL. polar edges other crystals are often very symmetrically re- peated, a central individual appearing like the support of all the others. Almost identical forms occur in chalcopyrite. In the hexagonal system twin crystals with parallel axes are common, as in calc-spar, chabasite, haematite, and other rhombohedral minerals. In calc-spar they often form very regular crystals, the two individuals uniting by a plane parallel to the base, so as to appear like a single crystal, as in Fig. 78, where each end shows the forms ooE — ^E, but in a complementary position ; or in Fig. 79 of two scalenohedrons E3 from Derbyshire. The rhombohedric crystals of chabasite often appear intersecting each other, like those of fluor spar in Fig. 73 above. The purer varieties of quartz or rock- \c 4"-'-' \c' \c ! Fig. 78. Fig. 79. Fig. 80. crystal, in consequence of the tetartohedral character of its crystallisation, often exhibit twins. In these the pyramid P separates into two rhombohedrons P and r, which, though geometrically similar, are yet physically dis- tinct. In Fig. 80 the two individuals are only grown to- HEXAGONAL. 45 gether, but more commonly they penetrate each other in an irregular manner, forming apparently a single crystal. Twins with oblique axes are also common, the plane of union being usually one face of the rhombohedron. Thus in calc-spar two rhombohedrons are often joined by a face of — ^R, the Fig. 81. Fig. 82. two axes forming an angle of 127° 34' ; occasionally a third individual is interposed in a lamellar form, as in Fig. 81, when the two outer crystals become parallel. This latter ar- rangement is very common in the highly cleavable varieties or Iceland spar. When the crystals unite in a face of the rhombohedron R, Fig. 82, they form an angle of 89° 8', differing little from a right angle, by which the occurrence of this law is very easily recognised, especially in prismatic varieties. Fig. 83. Fig. 84. Fig. 85. In the rhombic system twin crystals with parallel axes are very rare, but those with oblique axes common, the plane 46 MACLES — KHOMBIC. of union being one of the faces of the prism ooP. Twins of this kind are very distinctly seen in arragonite, cerussite, marcasite, stephanite, mispickel, and other minerals. In arragonite the crystals partly interpenetrate, partly are in mere juxtaposition, as in Fig. 83, where the individuals are formed by the combination ooP(m) . ooPoc (A), Poo (^), and in Fig. 84 where several crystals of the same combination form a series with parallel planes of union ; the inner mem- bers being so shortened that they appear like mere lamellar plates producing striae on the faces Poo and ooPoo of the made. In Fig. 85 four crystals, each of the combination ooP . 2Poo , having united in inclined planes, form a circular group, returning into itself. Cerussite often occurs in macles Fig. 86. Fig. 87. in all respects similar. In staurolite, individuals of the prism- atic combination ooP . ooPoo . OP, combine either, as in Fig. 86, by a face of the brachydome f Poo , with their chief axes almost at right angles ; or, as in Fig. 87, by a face of the brachypyramid f Pf , the chief axes and the brachypina- coids (o) of the two single crystals meeting at an angle of about 60°. Harmotome (Fig. 88) is often regarded as form- ing macles of two crystals intersecting so nearly at right angles that their principal axes seem to coincide. In the monoclinic system the most common macles are those in which the principal axes and the chief sections of MONOCLINIC. 47 the two crystals are parallel to each other, and consequently the principal axis is also the twin axis. Usually the two individuals are united by a face parallel to the orthodiagonal chief section, as in Figure 89 of gypsum, where two crystals of the combination ooP'^oo . ooP. - P, shown in Fig. 59, unite M II Fig. 88. Fig. 89. Fig. 90. SO regularly that the faces of the pinacoids (P and P) form only one plane. In a similar manner the augite crystals of the combination ocP . ooP'oo . ooP'oo . P, represented singly in Fig. 60, are in Fig. 90 united in a made so very symme- trical and regular that the line of junction cannot be observed on the face of the clinopinacoid. The two hemipyramids P {s) (like - P (/) in the gypsum crystal above) form on one side a re-entering, on the other a salient angle. Hornblende, wolfram, and other minerals, exhibit a similar ap- pearance. In other cases the indi- viduals partially penetrate each other, being, as it were, crushed together in the direction of the orthodiagonal. This mode of union is not uncommon in gypsum, and very frequent in orthoclase felspar, crystals of the latter, of the combination ooP'^oo . ooP SP^oo, as in Fig. 61 above, are often pushed side wise into each other as shown in Fig, 91. Fig. 91. Two OP. 48 MACLES — TRICLINIC. In the triclinic system some twin formations are of great importance as a means of distinguishing the triclinic from the monoclinic species of felspar. In one variety the twin axis is the normal to the brachy diagonal chief section. But in the triclinic felspars this section is not perpendicular to the bases, and consequently the two bases form on one side a re-entering, on the other a salient angle ; whereas in the monoclinic felspars (where the brachydiagonal chief sec- tion corresponds to the clinodiagonal) no twin crystals can be produced in conformity to this law, and the two bases fall in one plane. The albite and oligolase very often exhibit such twins as in Figure 92, where the very obtuse angles Fig. 92. Fig. 93. formed by the faces of OP, or P and P (as well as those of 'T'oo , or X and x') are a very characteristic appearance, marking out this mineral at once as a triclinic species. Usually the twin formation is repeated, three or more crys- tals being combined, when those in the centre are reduced to mere plates. When very numerous, the surfaces P and X are covered with fine strise, often only perceptible with a microscope. A second law observed in triclinic felspars, particularly the albite and labradorite, is that the twin axis corresponds with that normal of the brachydiagonal which is situated in the plane of the base. In pericline, a variety of albite, these twins appear as in Fig. 93, where the two crystals are united by a face of the basil pinacoid P, whilst the faces of the two brachypinacoids {M and ]\T) form edges CRYSTALLINE AGGREGATES. 49 with very obtuse angles (173° 22^, re-entering on the one side and salient on the other. These edges, or the line of junction between M and M', are also parallel to the edges formed by these faces and the base, or those between M and F. In this case also the macles are occasionally several times repeated, when the faces appear covered with fine striae. Irregular Aggregation of Crystals. Besides the regular unions now described, crystals are often aggregated in peculiar ways, to which no fixed law can be assigned. Thus some crystals, apparently simple, are composed of concentric crusts or shells, which may be removed one after the other, always leaving a smaller crys- tal like a kernel, with smooth distinct faces. Some speci- mens of quartz from Beeralston in Devonshire consist ap- parently of hollow hexagonal pyramids placed one within another. Other minerals, as fluor spar, apatite, heavy spar, and calc-spar, exhibited a similar structure by bands of dif- ferent colours. Many large crystals, again, appear like an aggregate of numerous small crystals, partly of the same, partly of dif- ferent forms. Thus some octahedrons of fluor spar from Schlaggenwald are made up of small dark violet-blue cubes, whose projecting angles give a drusy character to the faces of the larger form. Such polysynthetic crystals, as they may be called, are very common in calc-spar. A similar, but still more remarkable formation, is where two crystals of distinct species are conjoined. Such unions of cyanite and staurolite have been long well known, and the graphic granite exhibits a similar union between large felspar crystals and many smaller ones of mica and quartz. Forms of Crystalline Aggregates.— Crystals have often been produced under conditions preventing the free deve- lopment of their forms. They then compose crystalline aggregates, of which the following may be distinguished :— Granular, formed of grains, generally angular, but rarely rounded or flattened. Lamellar consist of broad plates, which are tabular when of uniform thickness, lenticular E 50 CRYSTAL GROUPS. when becoming thinner on the edges, wedge-shaped when sharpened towards one edge, and scaltj when the plates are very small. Columnar, in which the individuals are drawn out in one direction more than in the others ; hacillary or rod-like, in which the columns are of uniform thickness ; acicular or needle-shaped, in which they are pointed ; and fibrous, in which they are very fine. In the broad-colum- nar the columns are, as it were, compressed, or broader in one direction than the other. The distinctions of large, coarse, small, or fine-granular ; thick or thin scaly ; straight, curved, or twisted- columnar ; parallel, diverging, or con- fused-fibrous ; and such like, are easily understood. Aggregates which have been able to crystallise, at least with a certain degree of freedom, have been distinguished by Mohs into crystal groups and druses ; the former includ- ing all unions of several imbedded crystals with no distinct basis ; the latter those of crystals that have grown together on a common support. In the groups crystals with their faces otherwise perfect are conjoined in various ways. Sometimes they radiate, as it were, from a common centre, and produce spheroidal, ellipsoidal, or other forms, frequent in gypsum, iron pyrites, and other minerals imbedded in clay. Where many such masses are united, they are named hotryoidal when like bunches of grapes, mammeUated where the spheres are larger and less distinct, and reniform- or kid- ney-shaped where the masses are still larger. Some groups are partially attached by a small point ; but the mass is generally free. Crystals are often grouped in rows or in one direction, forming, when they are very small, capillary or hair-like, and filiform, thread, or wire-like forms, which are common among native metals, as gold, silver, copper, and bismuth, in argentite and a few other minerals. Sometimes the masses are dentiform, consisting of portions resembling teeth ; as is very common in silver. Often these groups expand in several directions, and produce arborescent, den- dritic, foliated, feathered, or other forms, very common in copper. In these groups, however, a certain dependence on the crystallographic cliaracter of the species may be ob- DRUSES. 51 served. The lamellar minerals often form fan-shaped, wheel- like, almond-shaped, comb-like, or other groups. The fibrous types, again, are disposed in parallel or diverging bundles, or in radiating, stellar, and other masses. Coral- loidal (like coral), fruticose (like cauliflower), and other forms, have also been observed. In druses, many crystals rise side by side from a common support ; in some only the granular mass composed of their united bases, in others a distinct body. The form of a druse is determined by that of the surface on which it grows, and consequently is often very irregular or wholly acci- dental. Where completely inclosed they have been named drusy cavities, and when of a spheroidal form, geodes. A drusy crust, again, consists of a thin layer of small crystals investing the surface of a large crystal or of some other body. The minute or cryptocrystalline minerals form similar aggregates. When globular or oolitic the minute crystals often appear to radiate from a centre, or form concentric crusts. Somewhat similar are the stalactites and stalagmites, m which the mineral, especially rock-salt, calc-spar, chalce- dony, opal, limonite, has been deposited from a fluid dropping slowly from some overhanging body. In this case the prin- cipal axis of the figure, generally a hollow tube, is vertical, whilst the individual parts are arranged at right angles to it. ^ In other cases the mineral has apparently been de- posited from a fluid mass moving slowly in a particular direction, which may be regarded as the chief axis of the figure, whilst the axes of the individual crystals may assume a difl'erent position. By far the largest masses of the mineral kingdom have, however, been produced under conditions in which a free development of their forms was excluded. This has been the case with the greater portion of the minerals com- posing rocks or filling veins and dykes. The structure of these masses on the large scale belongs to geology, but some varieties of the texture, visible even in hand specimens, may be noticed. The individual grains or masses have seldom any regular form, but appear round, long, or flat. UNIVERSITY OF laiNOlS UBRARX 52 PSEUDOMORPHISM. according to circumstances, and as each has been more or less checked in the process of formation. Even then, how- ever, a certain regularity in the position of the parts is often observable, as in granite, in which the cleavage planes, and consequently the axes of the felspar crystals, are parallel. Where these grains are all pretty similar in size and shape, the rock is named massive when they are small, or granular when they are larger and more distinct. Sometimes the rock becomes slaty, dividing into thin plates ; or con- cretionary, forming roundish masses ; at other times the interposition of some foreign substance (gas or vapour) has rendered it porous, cellular, or vesicular, giving rise to drusy cavities. These cavities are often empty, but have occasion- ally been filled by other minerals, when the rock is named amygdaloidal, from the almond-like shape of the inclosed masses. Many of the above external forms appear also in the amorphous solid minerals, in which no trace of individual parts, and consequently of internal structure, is observable. They are not unfrequently disposed in parallel or concen- tric layers, of uniform or distinct colours ; and may assume spherical, cylindrical, stalactitic, and other appearances. Pseudomorphism, When the substance of one mineral assumes the external form of some other mineral it is named a pseudomorph. In some named incrusting pseudomorphs the original crystal is covered by a rough or drusy surface of the second mineral, frequently not thicker than paper. Occasionally the first crystal has been removed, and the shell alone remains ; or the cavity has been filled by a distinct mineral species, or a crystalloid, as it may be named, forming an exact repre- sentation of the original, but of a difi'erent substance. More commonly the new mineral substance has gradu- ally expelled the old, and replacing it, as it were, atom by atom, has assumed its exact form. In other cases not the whole substance of the original crystal, but only one or more of its elements, has been changed, or the whole matter has remained, but in a new condition. Thus arragonite PETRIFACTION". 53 crystals have been converted into calc-spar, the chemical composition of both being identical ; or gaylussite has been changed into calc-spar, andalusite into cyanite, by the loss of certain elements. On the other hand, anhydrite be- comes gypsum, cuprite malachite, by addition of new matter. ^ Or the elements are partially changed, as felspar into kaolin, iron pyrites into haematite or limonite, azurite into malachite, augite into green earth. The true nature of such bodies is shown by the internal structure having no relation to the external form or apparent system of crystal- lisation. The process of petrification of organic bodies is in reality a species of pseudomorphic formation, and has been pro- duced in all the above modes. External and internal casts of organic bodies are not uncommon. In other cases the original substance has been replaced by some mineral which has preserved not merely the external form, but even the minutest detail of internal structure ; so that the different kinds of wood have been distinguished in their silicified trunks. The most common petrifying substances are silica and carbonate of lime. In encrinites, echinites, belemnites, and other fossils, the crystals of calc-spar often occur in very regular positions. In some varieties of petrified wood both the ligneous structure and the cleavage of the calc- spar are observable. Different from the above are mineralised bodies, in which the original structure is still retained, but their che- mical nature partially changed. In these a complete series may be often traced, as from wood or peat, through the varieties of brown coal, common coal, anthracite, and gra- phite, perhaps even to the diamond. 54 PHYSICAL PROPEKTIES. CHAPTER 11. PHYSICAL PROPERTIES OF MINERALS. The physical character of minerals comprehend — I.5/, Those properties derived from the nature of the substance itself, as coherence, mode of fracture, elasticity, and density or specific gravity. 2d, Those phenomena called forth in minerals by the influence of some external power or agent, as their optical, electric, or thermal relations ; and, 3d, Other characters depending on the personal sensation of the observer, on his taste, smell, and touch. All these pro- perties furnish useful characters in distinguishing and de- scribing mineral species. Cleavage and Fracture, In many species there are certain planes, at right angles to which cohesion seems to be at a minimum, so that the mineral separates along, or parallel to, these planes far more readily than in any other direction. This property is named cleavage, and these planes cleavage-planes. They have a strictly definite position, and do not show any trans- ition or gradual passage into the greater coherence in other directions. The number of these parallel cleavage- planes is altogether indefinite ; so that the only limit that can be assigned to the divisibility of some minerals, as gyp- sum and mica, arises from the coarseness of our instruments. These minima of coherence or cleavage-planes are always parallel to some face of the crystal, and similar equal minima occur parallel to every other face of the same form. Hence they are always equal in number to the faces of the form, and the figures produced by cleavage agree in every point with true crystals, except that they are artificial. They are thus most simply and conveniently described by CLEAVAGE. 55 the same terms and signs as the faces of crystals. Some minerals cleave in several directions parallel to the faces of different forms, but the cleavage is generally more easily obtained and more perfect in one direction than in the others. This complex cleavage is well seen in calc-spar and fluor spar, and very remarkably in zinc-blende, where it takes place in no less than six directions. As in each of these the division may be indefinitely continued, it is clear that no lamellar structure in any proper sense can be as- signed to the mineral. All that can be affirmed is, that contiguous atoms have less coherence in the normal of these planes than in other directions. When the cleavage takes place in three directions, it, of course, produces a perfect crystal form, from which the system of crystallisation and angular dimensions of the species may be discovered, and is thus often of very great importance. The common cleavage in the different systems is as fol- lows, those of most frequent occurrence being put in italics : — (1.) In the tesseral. Octahedral^ 0, along the faces of the octahedron ; Hexahedral, oo 0 qo , along those of the cube ; and Dodecahedral, ooO. (2.) In the tetragonal system. Pyramidal, P or 2Poo ; Prismatic, ooP or ooPoo ; or Basal , OP. (3.) In the hexagonal system with holohedral forms. Pyramidal, P or P2 ; Prismatic, ooP or ooP2 ; or Basal OP ; with rhombohedral forms, Bhombohedral, E ; Pris- matic, ooE ; or Basal, OR (4.) In the rhombic system, Pyramidal, P ; Prismatic, ooP ; Makro or Brachydomatic, Pco or Poo ; Basal, OP; Macrodiagonal, ooPoo ; or Brachydiagonal, ooPoo . (5.) In the monoclinic system, Hemipyramidal, P or — P 3 Prismatic, 00 P; Clinodomatic, P'co; Hemidomatic, P'oo or -P^oo ; Basal, OP j Ortho- diagonal, GoP^'oo j or Clinodiagonal, ooP'^oo . (6.) In the triclinic system, Hemiprismatic, 00 P' or cx)P ; Hemido- matic either along the macrodome or brachydome ; Basal, OP; Macrodiagonal, ooPoo ; ov Brachydiagonal, 00 Poo. In some minerals, as mica and gypsum, the cleavage is readily procured; these may be held in the hand and divided by a knife. Others only cleave with more or less 66 FRACTURE. difficulty ; these must be placed on a firm support resting on lead, folded paper, or cloth, and a sharp blow struck on a chisel applied in a proper direction. This may often be ascertained by examining the specimen in a strong light. The planes produced also vary much in their degree of perfection, being highly perfect in some, as mica and calc- spar; imperfect in others, as garnet and quartz. In a very few crystalline minerals cleavage-planes can hardly be said to exist. Cleavage must be carefully distinguished from the planes of union in twin crystals, and the division- planes in the laminar minerals. Fracture Surfaces are formed when a mineral breaks in a direction different from the cleavage-planes. They are consequently most readily observed when the cleavage is least perfect. The form of the fracture is named conchoidal when composed of concave and convex surfaces like shells, even when nearly free from inequalities. The character of the surface is smooth ; or splintery when covered by small wedge-shaped splinters adhering by the thicker end ; or hackly when covered by small slightly-bent inequalities, as in iron and other malleable bodies; or earthy when it shows only fine dust. Hardness and Tenacity, The hardness of minerals, or their power of resisting any attempt to separate their parts, is also an important character. As it difi*ers considerably in the same species, according to the direction and the surface on which the trial is made, its accurate determination is difficult, and the utmost that can usually be obtained is a mere approxima- tion found by comparing different minerals one with an- other. For this purpose Mohs has given the following scale : — 1. Talc, of a white or greenish colour. 2. Rock-salt, a pure cleavable variety, or semi-transparent uncrystal- Used gypsum, the transparent and crystallised varieties being generally too soft. 3. Calc-spar, a cleavable variety. 4. Fluor spar, in which the cleavage is distinct. 5. Apatite, the as] aragus-stone, or phosphate of lime. HAEDNESS. 57 6. Adularia felspar, any cleavable variety. 7. Rock-crystal, a transparent variety. 8. Prismatic topaz, any simple variety. 9. Corundum from India, which affords smooth cleavage surfaces. 10. The Diamond, Two other degrees are obtained by interposing foliated mica between 2 and 3, and scapolite, a crystalline variety, between 5 and 6. The former is numbered 2 '5, the latter, 5 '5. To ascertain the hardness of a mineral, first try which of the members of the scale is scratched by it, and in order to save the specimens, begin with the highest numbers, and proceed downwards, until reaching one which is scratched. Then take a fine hard file, and draw along its surface, with the least possible force, the specimen to be examined, and also that mineral in the scale whose hardness is imme- diately above the one which has been scratched. From the resistance they offer to the file, from the noise occa- sioned by their passing along it, and from the quantity of powder left on its surface, their relative hardness is deduced. When, after repeated trials, we are satisfied to which mem- ber of the scale of hardness the mineral is most nearly allied, we say its hardness (suppose it to be felspar) is equal to 6, and write after it H. = 6*0. If the mineral do not exactly correspond with any degree of the scale, out is found to be between two of them, it is marked by the lower with a decimal figure added. Thus, if more than 6 but less than 7, it is expressed H. = 6*5. In these experi- ments we must be careful to employ specimens which nearly agree in form and size, and also as much as possible in the shape of their angles. Where the scale of hardness is wanting, or for a first rough determination, the following experiments may serve : — Every mineral that is scratched by the finger-nail has H. = 2*5 or less. Minerals that scratch copper have H. = 3 or more. Polished white iron has H. = 4*5. Window-glass has H. = 5 to 5 '5. Steel point or file has H. = 6 to 7. Hence every mineral that will cut or scratch with a good penknife has H. less than 6. Flint has H. = 7, and only about a dozen minerals, including the pre- ciows stones or gems, are harder. 68 TENACITY. Closely allied to hardness is the TENACITY of minerals, of which the following varieties have been distinguished : — A mineral is said to be brittle when, as in quartz, on attempting to cut it with a knife, it emits a grating noise, and the particles fly away in the form of dust. It is sed'ile or mild when, as in galena and some varieties of mica, on cutting, the particles lose their connection in a considerable degree ; but this takes place without noise, and they do not fly ofl; but remain on the knife. And a mineral is said to be soft or ductile when, like native gold or lead, it can be cut into slices with a knife, extended under the hammer, and drawn into wire. From tenacity it is usual to distinguish or the resistance which minerals oppose when we attempt to break them into pieces or frag- ments. This property must not be confounded with hard- ness. Quartz is hard, and hornblende comparatively soft ; yet the latter is more difficultly frangible than the former. FlexiUlity, again, expresses the property possessed by some minerals of bending without breaking. They are elastic, like mica, if, when bent, they spring back again into their former direction ; or merely flexible, when they can be bent in difi*erent directions without breaking, but remain in their new position, as gypsum, talc, asbestus, and all malleable minerals. Specific Gravity, The density or the relative weight of a mineral, com- pared with an equal volume of pure distilled water, is named its specific gravity. This is a most important cha- racter for distinguishing minerals, as it varies considerably in diff'erent species, and can be readily ascertained Avith much accuracy, and, in many cases, without at all injuring the specimen. The whole process consists in weighing the body, first in air, and then immersed in water, the diff"er- ence in the weight being that of an equal bulk of the latter fluid. Hence assuming, as is commonly done, the specific gravity of pure distilled water to be equal to 1 or unity, the specific gravity (G) of the other body is equal to its weight in air {w), divided by the loss or difiference {d) of SPECIFIC GKAVITY. 59 weight in water (or G- = |). A simple and portable instru- ment for finding the specific gravity is the areometer of Nicholson, Fig. 94. A delicate hydrostatic balance gives the gravity with most accuracy ; but a good common balance is often sufficient. The mineral may be suspended from one arm or scale by a fine silk thread or hair, and its weight ascertained, first in the air, and then in water. There are some precautions necessary to insure accuracy. Thus, a pure specimen must be selected which is not intermixed with other substances, and when weighed injair it should be quite dry. It must also be free from cavities, and care must be taken that when weighed in water no globules of air adhere to its sur- face, which render it lighter. If the body imbibes moisture, it should be allowed to remain till fully saturated before deter- mining its weight when immersed, and it is sometimes even necessary to boil the specimen in order to expel the air from its pores. Small crystals or fragments, whose freedom from mixture can be seen, are best adapted for the purpose. The specimen experimented on should not be too heavy ; thirty grains being enough where the gravity is low, and even less where it is high. It is also of importance to repeat the trial, if possible with diff'erent specimens, which will show whether any cause of error exists, and to take the mean of the whole. A correction should be made for the variation of the temperature of the water from 60° Fahr., which is that usually chosen as the standard in mineralo- gical works. Where the difi'erence, however, does not ex- ceed ten or fifteen degrees this correction may be neglected, as it only affects the third or second decimal figure of the result. Fig. 94. Areometer. 60 OPTICAL PKOPERTIES. Ojptical Properties of Minerals. There are few more interesting departments of science than the relations of mineral bodies to light, and the modi- fications which it undergoes either, 1st, when passing through them, or 2d, when reflected from their surface. In this place, how^ever, we only notice these phenomena so far as they point out distinctions in the internal constitu- tion of minerals, or furnish characters for distinguishing one species from another. Minerals, and even diff'erent specimens of the same species, vary much in pellucidity, or in the quantity of light which can pass through them. Some transmit so much light, that small objects can be clearly seen, or let- ters read when placed behind them, and are named trans- parent They are semitransparent when the object is only seen dimly, as through a cloud ; and translucent when the light that passes through is so obscured that the objects can be no longer discerned. Some minerals are only thus translucent on the thinnest edges, others transmit no light, and are named opaque. These degrees pass gradually into each other, and cannot be separated by any precise line ; and this is also the case in nature, where some minerals pass through the whole scale, as quartz, from the fine transparent rock-crystal to opaque dark-black varieties. Such minerals may be described generally as pellucid. This change often arises from some mixture in their com- position, especially of metallic substances. Perfect opacity is chiefly found in the metals or their compounds with sul- phur, though even these seem to transmit light when re- duced to laminae of sufiicient thinness. Double Refraction. — When a ray of light passes obliquely from one medium into another of difi'erent density, it is bent or refracted from its former course. The line which it then follows forms an angle with the perpendicular, which in each body bears a certain proportion to that at which the ray fell upon it, or, as definitely stated, the sine of the angle of refraction has a fixed ratio to the sine of the angle of incidence, this ratio being named the index of DOUBLE REFRACTION. 61 refraction. Simple refraction occurs in all transparent bodies, whether crystalline, amorphous, or fluid ; but some crystals produce a still more remarkable result. The ray of light which entered them as one is divided into two rays, each following a different angle, or is doubly refracted. In minerals of the tesseral system this property does not exist, but it has been observed in all minerals belonging to the other systems, though in some only after they have been cut in a particular manner, or have been otherwise properly prepared. It is most distinctly seen in crystals of calc-spar, especially in the beautiful transparent variety from Iceland, in which it was first observed and described by Erasmus Bartholin in a work published at Copenhagen in 1669. The subjoined figure will illustrate this singular pro- perty. It represents a rhomb of Iceland spar, on the sur- face of which a ray oflightjRr falls. As seen in the figure, this ray divides into two, one of which too' follows the or- dinary law of re- fraction, or the sines of the angles of in- cidence and refrac- tion maintain a con- stant ratio. This is named the or- dinary ray 0. The other, r^e', named the extraor- dinary ray E, does not obey the usual law of the sines, and has no general index of refraction. In the plane perpendicular to the axis of the crystal, it is most widely separated from the ordinary ray, but in others oblique to it approaches nearer to 0, and in one at right angles to the first coincides, or then shows no double refraction. This plane, or rather direction, in which there is no double refraction, is named the optical axis of the crystal, or the axis of double refraction. Now, in certain minerals it is found 62 DOUBLE EEFEACTION. that there is only one plane with this property, whereas in others there are two such planes, and they have in conse- quence been di^^.clecl into monoaxial and binaxial. To the former (monoaxial) belong all crystals of the tetragonal and hexagonal systems ; to the latter (binaxial) all those of the three other systems. In the former the optic axis coincides with, or is parallel to, the crystallographic chief axis. In some crystals the index of refraction for the extraordinary ray E is greater than for the ordinary ray 0 ; and in others it is smaller. AVhen greater, they are said to have positive (or attractive), when less, negative (or repulsive) double refraction. Quartz is an example of the former, the index of refraction, according to Mains, being for 0 = 1'5484, for E= 1*5 582 ; and calc-spar of the latter, the index of 0 beings 1-6543, of E= 1-4833. The index of E is in both cases taken at its maximum. It should be observed that the optic axes are not single lines, but directions parallel to a line, or innumerable parallel lines, passing through every atom of the crystal. It is also important to remark that this property divides crystals into three precise gTOups — the tesseral, ^vith single refraction ; the tetragonal and hexagonal, with double refrac- tion and monoaxial ; those of the three other systems also, double, but binaxial. It is therefore of use to determine the system to which a mineral belongs, but is not of great value as a character for distinguishing species. Polarisation of Light. — Intimately connected with this property is that of the polarisation of light, which being- more easily and precisely observable than double refraction, is in many cases of higher value as a mineralogical cha- racter. By this term is meant a peculiar modification which a ray of light undergoes, in consequence of which its capa- bility of being transmitted or reflected towards particular sides is either wholly or partially destroyed. Thus, if from a transparent prism of tourmaline two thin plates are cut parallel to its axis, they will transmit light, as well as the prism itself, when they are placed above each other with the chief axis of both in the same direction. But when the one slip of tourmahne is turned at right angles to the POLAEISATION OF LIGHT. 63 other, either no light at all or very little is transmitted, and the plates consequently appear black. Hence, in passing through the first slip the rays of light have acquired a peculiar property, which renders them incapable of being transmitted through the second, except in a parallel posi- tion, and they are then said to be polarised. The same property is acquired by a ray of light when reflected, at an angle of 35|-^ (or angle of incidence 541°), from a plate of glass, one side of which is blackened, or from some other non-metallic body. When such a ray falls on a second similar mirror at an equal angle, but so that the plane of reflection in the second is at right angles to that in the first, it is no longer reflected, but wholly absorbed. When, on the other hand, the planes of reflection are parallel, the ray is wholly and at any intermediate angle partially reflected. A ray of light polarised by reflection is also incapable of transmission through a tourmaline slip in one position, which, however, is at right angles to that in which a ray polarised by passing through another slip is not transmitted. In order to observe the polarisation of light, either two tourmaline plates, properly prepared, or this simple instru- ment will be found useful (Fig. 96). At one end of a hori- zontal board B a black mirror a is fixed. In the middle is a pillar to which a tube cd is fastened, with its axis directed Fig. 96. Polarising instrument. 64 POLAEISATION OF LIGHT. to the mirror at an angle of 35|°. On the lower end is a cover c, with a small hole in the centre, and at the upper end another cover with a small black mirror m attached to it by two arms, as in the figure, and also at an angle of 35|°. With this instrument the mirror m can be so placed in relation to a that the planes of reflection shall have any- desirable inclination to exhibit the simple polarisation of light. This instrument furnishes a simple test whether minerals that cleave readily into thin lamellae are optically monoaxial or binaxial. Place the two mirrors with their polarisation- planes at right angles, and fix a plate of the mineral with a little wax over the hole c, and then observe what takes place in the second mirror during the time that the cover c is turned round. If the mineral belongs to the binaxial system, the light from the first mirror a, in passing through it, is doubly refracted and has its polarisation changed, and consequently can be again reflected from the second mirror m, and in each revolution of c will show four maxima and four minima of intensity. If, on the contrary, the mineral is monoaxial, the ray will pass through the lamina unaltered, and will not be en- tirely reflected from the second mirror in any posi- tion of c. Another beautiful phe- nomenon of polarised light, in like manner connected with the crystalline struc- ture of minerals, is the coloured rings which la- minae of the doubly refract- ing species, when of a proper thickness, exhibit in certain positions. These rings are easily seen in the above appa- ratus, by interposing a thin plate of gypsum or mica be- tween the two mirrors. When the interposed plate be- longs to a monoaxial mineral, there is seen in the second mirror a system (Fig. 97) of circular concentric coloured rings Fig. 97. PLEOCHROISM. 65 intersected by a black cross. If the mineral is binaxial, one or two systems of elliptical coloured rings appear, each intersected by a black stripe (Fig. 98). In certain Fig. 98. Fig. 99. cases this stripe is curved, or the two systems of rings unite in a lemniscoidal form (Fig. 99). When the planes of polarisation are parallel, the black cross and stripe ap- pear white (Fig. 100), showing that =^ in this direction the crystals act like ^^^^ ^^^^ singly-refracting minerals. Quartz, ^^^^^ ^^^^^ again, in close relation to its system fff^^M ^^^^W of crystallisation, exhibits a circular ' ' " ^ ^- polarisation of splendid prismatic \y%\^^B ^^Jjjj colours, which on turning the plate ^^^^Js change in each point in the order of '^^^C ^^^^ the spectrum, from red to yellow, green, and blue. In order to pro- i^o. duce these changes, however, in some specimens the plate must be turned to the right, in others to the left, show- ing a difference in the crystalline structure. Pkochroism. — Closely connected with double refraction 66 PLAY OF LIGHT. is that property of transparent minerals named pleochroism (many-coloured), in consequence of which they exhibit dis- tinct colours when viewed by transmitted light in different directions. Crystals of the tesseral system do not show this property ; whilst in those of the other systems it ap- pears in more or less perfection ; and in the tetragonal and hexagonal minerals as dichroism (two colours), in the rhombic and clinic systems as trichroism (three colours). In most cases these changes of colour are not very decided, and appear rather as different tints or shades than as dis- tinct colours. The most remarkable of dichromatic min- erals are the magnesian mica from Vesuvius, the tourmaline and ripidolite; of trichromatic, the iolite, the andalusite from Brazil, the diaspore from Schemnitz, and the axinite. Some crystalline minerals exhibit a very lively play or change of colours from reflected light in certain directions. It is well seen in many various hues on the cleavage-planes of labradorite, and seems produced by a multitude of very thin quadrangular pores, interposed in the mineral like minute parallel laminae. On the cleavage-planes of the hypersthene it appears copper-red, and is occasioned by numerous small brown or black laminae of some foreign substance interposed in a parallel position between the planes of the hypersthene. The chatoyant, or changing colours of the sun-stone, arise from scales of haematite similarly interposed. The play of colour in the noble opal seems to be produced very nearly in the same manner with that in the labradorite. A similar opalescence is seen in certain minerals when cut in particular forms. In the sapphire, cut hemispherically over the chief axis, it appears like a star with six rays ; in certain varieties of chrysoberl and adularia it has a bluish tint ; and is also very remark- able in the cat's-eye variety of quartz. Iridescence often arises from very fine fissures, producing semicircular arches of prismatic tints, which, like the colours of thin plates in ixeneral, are referred to the interference of light. Lustre and Colour. Though these properties admit of no precise or mathe- LUSTRE. 67 matical determination, they are of considerable value in mineralogy. One highly important distinction founded on them is that of minerals of metallic and non-metallic aspect or character. This distinction can hardly be described in words, and the student will best learn to distinguish metallic colours and lustre from non-metallic, by observing them in nature. Transparency and opacity nearly coin- cide with this division, the metallic minerals being almost constantly opaque ; the non-metallic more or less trans- parent. Minerals which are perfectly opaque, and show metallic colour and lustre, are named metallic; those with only two of these three properties, semi-metallic or metalloid ; and those with the opposite properties, non- metallic. Lustre has reference to either the intensity or the quality of the reflected light, considered as distinct from colour. Several degrees in intensity have been named. (1.) Splen- dent, when a mineral reflects light so perfectly as to be visible at a great distance, and lively, well-defined images are formed in its faces, as galena, rock-crystal, or calc- spar. (2.) Shining, when the reflected light is weak, and only forms indistinct and cloudy images, as heavy spar. (3.) Glistening, when the reflected light is so feeble as not to be observable at a greater distance than arm's length, and no longer forms an image. (4.) Glimmering, when the mineral held near the eye in full clear daylight presents only a number of small shining points, as red haematite and granular limestone. When, as in chalk, the lustre is so feeble as to be indiscernible, it is said to be dull In regard to the kind or quality of the lustre, the fol- lowing varieties are distinguished :— (1.) The metallic, seen much perfection in native metals and their compounds with sulphur, and imperfectly in glance coal. (2.) Ada- mantine, found in beautiful perfection in the diamond, and m some varieties of blende and cerussite. (3.) Vitreous or glassy, seen in rock-crystal or common glass, or inclining to adamantine in flint-glass. (4.) Resinous, when the body appears as if smeared with oil, as in pitch-stone and gar- net. (5.) Pearly, like mother-of-pearl, seen in stilbite, 68 COLOUR. gypsum, mica. (6.) Silky, the glimmering lustre seen on fine fibrous aggregates like amianthus. Colour. — This property is not in all cases of equal value as a character. Thus some minerals are naturally coloured, showing in all modes of their occurrence one determinate colour, which is therefore essential, and forms a character- istic of the species. This class includes the metals, pyrites, blendes, with many metallic oxides and salts. A second class of minerals are colourless, their purest forms being w^hite, or clear like water, as ice, calc-spar, quartz, felspar, and many silicates. But these minerals are occasionally coloured, — that is, accidentally tinged, in some from the chemical or mechanical admixture of some colouring sub- stance, as a metallic oxide, carbon, or particles of coloured minerals ; in others, from the substitution of a coloured for an uncoloured element. The colours of these minerals, therefore, vary indefinitely, and never characterise the species, but only its varieties. Thus, quartz, calc-spar, fluor spar, gypsum, and felspar, are often coloured acci- dentally by pigments mechanically mixed ; and horn- blende, augite, garnet, and other colourless silicates, acquire green, brown, red, or black tints from the introduction of metallic elements. Werner, who bestowed much attention on this portion of mineralogy, distinguished eight principal colours, — white, grey, black, blue, green, yellow, red, and brown, — each with several varieties or shades arising from intermixture with the other colours. He also divided them into metallic and non-metallic as follows : — Metallic Colours. 1. White. — (1.) Silver-white, as in leucopyrite and native silver. (2.) Tin-white ; native antimony. 2. Grey. — (1.) Lead-grey ; galena or lead glance. (2.) Steel-grey ; native platina. 3. Jilack. — (1.) Iron-black ; magnetite. 4. Yelloio. — (1.) Brass-yellow ; chalcopyrite. (2.) Bronze-yellow ; iron pyrites. (3.) Gold yellow ; native gold. 5. Red. — (1.) Copper-red ; native copper and nickeline. Non-metallic Colours. 1. White. — (L) Snow-white ; new fallen snow, Carrara marble, and COLOUES. 69 common quartz. (2.) Reddish-white ; heavy spar. (3.) Yellowish- white ; chalk. (4.) Greyish-white ; quartz. (5.) Greenish-white ; amianthus.' (6.) Milk-white ; skimmed milk, chalcedony. 2. Grey.—{1.) Bluish-grey; limestone. (2.) Pearl-grey; porcelain jasper. (3.) Smoke-grey or brownish-grey ; dense smoke, dark varieties of flint. (4.) Greenish-grey ; clay slate. (5.) Yellowish-grey ; chalcedony. (6.) Ash-grey ; wood-ashes, zoisite, zircon, and slate-clay. 3. Black.— (1.) Greyish-black ; basalt. (2.) Velvet-black ; obsidian and schorl. (3.) Pitch-black or brownish-black ; cobalt ochre, bituminous coal. (4.) Greenish-black or raven-black ; hornblende. (5.) Bluish-black ; fluor spar. 4. Blue. — (1 .) Blackish-blue ; dark varieties of azurite. (2. ) Azure-blue ; bright varieties of azurite and Lapis lazuli. (3. ) Violet-blue ; amethyst and fluor spar. (4. ) Lavender-blue ; lithomarge and porcelain jasper. (5. ) Plum-blue ; spinel and fluor spar. (6.) Berlin-blue ; sapphire, cyanite. (7.) Smalt-blue ; pale-coloured smalt, gypsum. (8.) Duck-blue ; talc and corundum. (9.) Indigo-blue ; vivianite. (10.) Sky-blue ; liroconite. 5. Green.— {1.) Verdigris -green ; amazon stone. (2.) Celandine-green ; green earth, beryl. (3.) Mountain-green ; beryl, aqua-marine, topaz. (4.) Leek-green ; common actynolite and prase. (5.) Emerald-green ; emerald. (6.) Apple-green; chrysoprase. (7.) Grass -green ; uranite, smaragdite. (8.) Blackish-green ; augite and precious serpentine. (9.) Pistachio-green ; chrysolite and epidote. (10.) Asparagus-green ; the apatite or asparagus- stone. (11.) Olive-green ; garnet and olivine. (12.) Oil-green ; olive-oil, blende, beryl. (13.) Siskin green ; uranite and pyromorphite. 6. Yellow.— {1.) Sulphur-yellow ; native sulphur. (2.) Straw-yellow; pycnite. (3. ) Wax-yellow ; opal and wulfenite. (4.) Honey-yellow ; dark honey, fluor spar, and beryl. (5. ) Lemon-yellow ; rind of ripe lemons, orpiment. (6.) Ochre-yellow; yellow-earth and jasper. (7.) Wine-yel- low; topaz and fluor spar. (8.) Cream-yellow or Isabella-yellow; bole and compact limestone. (9.) Orange-yellow, rind of the ripe orange, uran- ochre, and some varieties of wulfenite. 7. Red.—(1.) Aurora, or morning-red ; zealgar. (2.) Hyacinth-red ; hya- cinth or zircon, and garnet. (3.) Tile-red ; fresh-burned bricks and heulandite. (4.) Scarlet-red ; light red cinnabar. (5.) Blood-red ; blood, pyrope. (6.) Flesh-red; felspar and barytes. (7.) Carmine-red; car- mme, spinel, particularly in thin splinters. (8.) Cochineal-red ; cinnabar. (9.) Crimson-red ; oriental ruby and erythrine. (10.) Columbine-red ; pre- cious garnet. (11.) Rose-red ; diallogite and rose-quartz. (12.) Peach- blossom red ; blossoms of the peach, red cobalt ochre. (13.) Cherry- red ; spinel and precious garnet. (14.) Brownish-red ; reddle and colum- nar-clay ironstone. 8. Brown.— (I.) Reddish-brown ; brown blende and zircon. (2.) Clove- brown ; the clove, rock-crystal, and axinite. (3. ) Hair-brown ; wood-opal and hmonite. (4.) Broccoli-brown ; zircon. (5.) Chestnut-brown; Egyptian .lasper. (6.) Yellowish-brown; iron-flint and jasper. (7.) Pinchbeck- brown ; tarnished pinchbeck, mica. (8.) Wood-brown ; mountain wood and old rotten wood. (9.) Liver-brown; boiled liver, common jasper. (10.) Blackish-brown ; mineral pitch and brown coal. The accidentally coloured minerals sometimes present I 70 PHOSPHORESCENCE. two or more colours or tints, even on a single crystal ; very remarkable examples occurring in fluor spar, apatite, sapphire, amethyst, tourmaline, and cyanite. This is still more com- mon in compound minerals, on which the colours are variously arranged in points, streaks, clouds, veins, stripes, bands, or in brecciated and ruin-like forms. Some minerals again change their colour from exposure to the light, the air, or damp. Then either the surface alone is aftected or tanushed, and appears covered as Avith a thin film, producing in some minerals, as silver, arsenic, bismuth, only one colour ; in others, as chalopyrite, hi^^matite, stibine, and common coal, various or iridescent hues. Or occasionally the change pervades the whole mineral, the colour either becoming paler, or disappearing as in chrysoprase and rose- quartz ; or darker, as in brown spar, siderite, and rhodo- nite. In a few minerals a complete change of colour takes place, as in the chlorophieite of the Western Isles, which, on exposure for a few hours, passes from a transparent yellow-green to black. These mutations are generally con- nected with some chemical chans^e. The tarnished colours sometimes only appear on certain faces of a crystal belong- ing to a peculiar form. Thus a crystal of copper pyrites (like Fig. 35) has one face P' free from tarnish ; the faces b and c, close to P', dark-blue ; the remainder of c, first violet, and then, close to P, gold-yellow. Streak is the colour of the powder formed when a mineral is scratched by a hard body. This is often different from that of the solid mass, and is very characteristic of many minerals. It also often shows a peculiar lustre where the mineral is soft, as in talc and steatite. Phosjphorescence, Eledriciti/, Magnetism, Phosphorescence is the property possessed by particular minerals of producing liglit in certain circumstances with- out combustion or ignition. Thus some minerals appear luminous when taken into the dark after being for a time exposed to the sun's rays, or even to the ordinary daylight. Many diamonds and calcined barytes exhibit this property in a remarkable degree ; less so, arragonite, calc-spar, and ELECTEICITY. 71 chalk. Many minerals, including the greater part of those thus rendered phosphorescent by the influence of the sun, also become so through heat. Thus some topazes, dia- monds, and varieties of fluor spar become luminous by the heat of the hand ; other varieties of fluor spar and the phosphorite require a temperature near that of boiling water ; whilst calc-spar and many silicates are only phos- phorescent at from 400° to 700° Fahr. Electricity pro- duces it in some minerals, as in green fluor spar and cal- cined barytes. In others it is excited when they are struck, rubbed, split, or broken ; as many varieties of zinc- blende and dolomite when scratched with a quill, pieces of quartz when rubbed on each other, and plates of mica when suddenly separated. Friction, pressure, and heat also excite electricity in minerals. To observe this property delicate electroscopes are required, formed of a light needle, terminating at both ends in small balls, and suspended horizontally on a steel pivot by an agate cup. Such an instrument can be electri- fied negatively by touching it with a stick of sealing-wax, excited by rubbing, or positively, by only bringing the wax so near as to attract the needle. When the instrument is in this state, the mineral, if also rendered electric by heat or friction, will attract or repel the needle according as it has acquired electricity of an opposite or similar kind ; but if the mineral is not electric, it will attract the needle in both conditions alike. Most precious stones become elec- tric from friction, and are either positive or negative according as their surface is smooth or rough. Pressure even between the fingers will excite distinct positive elec- tricity in pieces of transparent double-refracting calc-spar. Topaz, arragonite, fluor spar, carbonate of lead, quartz, and other minerals, show this property, but in a much smaller degree. Heat or change of temperature excites electricity in many crystals, as in tourmaline, calamine, topaz, calc-spar, beryl, barytes, fluor spar, diamond, garnet, and others, which are hence said to be thermo- or pyro-electric. Some acquire polar pyro-electricity, or the two electricities appear in 72 MAGNETISM — SMELL — TOUCH. opposite parts of the crystal, which are named its electric poles. Each pole is alternately positive and negative — the one when the mineral is heating, the other when it is cooling. As already noticed, many polar electric minerals are also remarkable for their hemimorphic crystal forms. Magnetism, or the power to act on the magnetic needle, is very characteristic of the few minerals in which it occurs, chiefly ores of iron or nickel. It is either simple, attracting both poles of the needle ; or polar, when one part attracts, and another repels the same pole. Some magnetic iron ores possess polar magnetism, or are natural magnets ; whilst the common varieties, meteoric iron, magnetic pyrites, precious garnet, and other minerals, are simply magnetic. Most minerals are only attracted by the magnet, but do not themselves attract iron. Smelly taste, and touch furnish a few characters of minerals. Most have no smell, but some give out a peculiar odour when rubbed : as quartz an empyreumatic odour, or smell of burning ; fluor spar of chlorine ; clay of clay ; some lime- stones and marls of bitumen, or a foetid odour. Aluminous minerals acquire a smell when breathed on. Other odours caused by heat, and often highly characteristic, are noticed under tests by the blow-pipe. Taste is produced by all the salts soluble in water. Some are saline like common salt ; sweetish astringent, like alum ; astringent, like blue vitriol ; bitter, like epsom salt ; cooling, like saltpetre ; pungent, like sal-ammoniac ; alkaline, like soda ; acid or sour, like sassoline, etc. Touch. — Some minerals are distinguished by a greasy feeling like talc ; others feel meagre, like clay ; others cold. The last character readily distinguishes true gems from their imitations in glass. CHEMICAL PROPERTIES OF MINERALS. 73 CHAPTER III. CHEMICAL PROPERTIES OF MINERALS. The consideration of the chemical nature of minerals — that is, of the elements that enter into their composition — of the manner in which these elements are combined, and the variations in proportion which they may undergo without destroying the identity of the species — forms an important branch of mineralogical science. The methods of detecting the different elements, and particularly the characters thus obtained for the discrimination of minerals, are also of much value. This is especially true of the metallic ores and other substances sought for their economic qualities. N.B. — It is well known that views and theories regard- ing the chemical constitution of mineral bodies different from those of Berzelius, have recently been adopted by many dis- tinguished mineral chemists. These views, however, affect only the theoretical constitution of minerals as expressed in formula, leaving the actual composition of the body, as stated in analyses by percentages, unchanged. It has therefore seemed to me better, in what must be regarded as a transition state of the science, to retain the old language and formula as probably most acceptable to the greater number of those using this work. No new rational formulae, also, have as yet definitely taken the place of the old Berzelian formulae, which, from their short condensed form, are more readily caught by the eye, and more easily remembered, than any that have been substituted for them. In the following Tables, however, both the old and new atomic weights are given; and in the more important species, 74 COMPOSITION^ OF MINERALS. the new formulae are added, distinguished by being put in [ ]; thusH-[ffOp^ Composition of Minerals. At present above sixty elements, or substances which have not been decomposed, are known. These are divided into metallic and non-metallic, a distinction of importance in mineralogy, though not always to be carried out with pre- cision. The non-metallic elements are rarely of semimetallic aspect, and are bad conductors of heat and electricity. Some of them are commonly gaseous — oxygen, hydrogen, nitrogen, chlorine, and fluorine ; one fluid — bromine ; the others solid — carbon, phosphorus, sulphur, boron, selenium, silicium or silicon, and iodine. The metallic elements are, except mercury, solid at usual temperatures, have generally a metallic aspect, and are good conductors of heat and electricity. They are divided into light and heavy metals, the former with a specific gravity under 5, and a great affinity for oxygen, and again distinguished as either alkali- metals, potassium (or kalium), sodium (or natrium), lithium, barium, strontium, and calcium ; — or earth metals, mag- nesium, lanthanium, yttrium, glucinum, aluminium, zir- conium. The heavy metals, with a specific gravity above 5, are divided into noble, which can be reduced, or separated from oxygen, by heat alone ; and ignoble, whose affinity for oxygen renders them irreducible without other agents. Some of the latter are brittle and difficultly fusible — thorium, titanium, tantalium, tungsten (wolframium), molyb- * Naummann, in the last edition of his valuable Manual, follows the same course, for reasons more fully stated. — See Elemente der Mineralogie, 8te Auf. 1871, pp. 150-153. We quote one sentence only : — " Es bedarf wohl dieses Verfahren um so weniger einer Entschuldignng, als doch noch manche recht bedeutende Chemiker sich der alteren, nach Berzelius' Methode geschriebenen Fornieln bedienen, und als gar nicht gelaugnet werden kann, dass diese Formeln eine sehr klare und compen- diose Uebersicht der qualitativen und quantitativen Zusammensetzung der Mineralien gevviihren, dem practischen Bediirfnisse des Hiittenmannes und Technikers vollkonimen Geniige leisten, uud sich sehr leicht in die modernen empirischen Formeln iibersctzen lassen." ELEMENTS — SYMBOLS. 75 denum, vanadium, chromium, uranium, manganese, and cerium ; others are brittle and easily fusible or volatile — arsenic, antimony, tellurium, and bismuth ; and others malleable — zinc, cadmium, tin, lead, iron, cobalt, nickel, and copper. The noble metals are — quicksilver, silver, gold, platinum, palladium, rhodium, iridium, and osmium. All the chemical combinations observed in the mineral kingdom follow the law of definite proportions ; that is, two elements always combine either in a fixed proportion, or so that the quantity of the one is multiplied by two, three, four, or some other definite number seldom very large. As this law prevails throughout the whole range of elements, by assuming any one, usually hydrogen, as unity or 1, and determining from experiment the simple propor- tion in which the others combine with it, a series of numbers is obtained which also expresses the proportions in which all these elements combine with each other. These numbers, therefore, mark the combining proportions or equivalents, as they are named, of the elements. They are also named atomic weights, on the supposition that matter consists of definite atoms, and that its combinations consist of one atom (or sometimes two atoms) of one sub- stance, with one, two, three, or more atoms of another. This theory is not free from difficulties, but the language is convenient. To designate the elements, chemists generally employ the first letter or letters of their Latin names. These signs also indicate one atom or equivalent of the element. Thus, 0 means oxygen in the proportion of one atom ; H, hydrogen in the same proportion ; I^T, an atom of nitrogen ; Na, an equivalent proportion of natrium or sodium. These signs and the equivalent weights are given in the following Table, in which hydrogen is taken as unity : — TABLE OF ELEMENTS. TABLE I. — Elements, etc. Atomic Weight. "M A A/TIT' IN AMili. bign. UiQ. New. Aluminium Al 13-7 27-5 tAntimony Sb 122 122 tArsenic - - - - As 75 75 Barium - - - - Ba 68-5 137 t Bismuth _ _ _ Bi 208 208 t Boron . - - - B 11 11 t Bromine Br 80 80 Cadmium - Cd ' 56 112 Caesium Cs 133 Calcium Ca 20 40 Carbon - - - - C 6 12 Cerium - - - - Ce 46 92 t Chlorine CI 35-5 35-5 Chromium _ - - Cr 26-1 52-2 Cobalt - - . - Co 30 60 Copper - - - - Cu 31-7 63-4 Didymium - D 95 t Fluorine Fl 19 19 Glucinum Gl 4-6 9-2 tGold . - - - Au 197 197 t Hydrogen H 1 1 Indium - - - - In 72 t Iodine - - - - I 127 127 Iridium - Ir 99 198 Iron - . - - Fe 28 56 Lanthanium - La 46 92 Lead _ . - - Pb 103-5 207 tLithium Li 7 7 Magnesium Mg 12 24 Manganese . _ - Mn 27-5 55 Mercury Hg 100 200 Molybdenum - Mo 48 96 Nickel - - - - Ni 29 58 TABLE OF ELEMENTS. 77 TABLE I. — Elements, etc. — continued. Atomic Weight, oign. Old. New. Niobium m 47 94 t Nitrogen 14 14 Osmium - _ _ Os 100 200 Oxygen - 0 8 16 Palladium Pd 53 106 t Phosphorus P 31 31 Platinum Pt 99 198 tPotassium K 39 39 Ehodium Eh 52 104 Eubidium Eb 85-5 Euthenium Eu 52 104 Selenium Se 39-5 79 Silicium Si 14 28 t Silver - . _ _ Ag 108 108 tSodium - - - - Na 23 23 Strontium - - . Sr 44 88 Sulphur S 16 32 Tantalium Ta 91 182 Tellurium Te 64 128 Thallium Tl 204 Thorium Th 115-7 231-4 Tin - - - - Sn 59 118 Titanium Ti 25 50 Tungsten W 92 184 Uranium U 60 120 Vanadium V 68-6 137-2 Yttrium Y 30-8 61-6 Zinc - - . . Zn 32-8 65-6 Zirconium Zr 44-8 89-6 be seen that the elements marked t have the same atomic weights both theories, whilst the others are doubled on the new theory. 78 COMPOUNDS — SIGXS. All these elements occur in minerals, but not more than twenty are common, and only about twelve abundant. They are also very rare in their simple or uncombined state ; carbon (in the diamond and graphite), sulphur, and about a dozen of the native metals only, being thus known. More frequently minerals consist of two or more elements combined in accordance with those laws which prevail in inorganic compounds. The most important of these laws is that the combinations are binary ; that is, that the ele- ments unite in pairs, which may again unite either with another compound of two, or with a single element. Inor- ganic compounds, also, are generally distinguished from organic by their greater simplicity. The following principles are observed in designating the combinations of these elementary substances : — For those of the first order the signs of the tw^o components are con- joined, and the number of atoms or equivalents of each expressed by a number follow^ing the sign, like an algebraic exponent. Thus, SO, SO^, SO^ are the combinations of one atom of sulphur with one, two, or three atoms of oxy- gen ; FeS, FeS"^, of one atom of iron with one or two of sulphur. But as combinations with oxygen and sulphur are very numerous in the mineral kingdom, Berzelius marks the atoms of oxygen by dots over the sign of the other element, and those of sulphur by an accent ; the above compounds being then designated thus — S, S, S, and Fe', Fe''. In some cases two atoms of a base combine with three or five of oxygen or sulphur, as Al^O^ Fe'S^ In such cases Berzelius marks the double atom by a line drawn through the sign of the single atom ; thus Al is two atoms aluminium with three of oxygen or alumina ; €u, two of copper with one of oxygen or oxide of copper. Where a number is prefixed to the sign, like a coefticient in algebra, it includes both elements of the combination ; thus H is one atom water, 2 li two atoms ; CaC is one atom carbonate of lime, 2 CaC two atoms, including, of course, two of calcium, two of carbon, and six of oxygen. The most common and important binary compounds OXYGEN COMPOUNDS. 79 are those with oxygen, contained in the following Table, with their signs, atomic numbers, and amount of oxygen in 100 parts. The more electro-negative are named acids, which are often soluble in water, and then render blue vegetable colours red. The more electro-positive are named oxides or bases, and show great affinity or attractive power for the former. The most powerful are the alkaline bases, which are colourless and soluble in water ; less powerful are the earths, also colourless, but insoluble in water : TABLE II. — Binary Compounds with Oxygen. A cinie. Old Atoms. New Atoms. Alumina - - _ Ai 51-4 APQS 102-8 Antimony oxide Sb 146 Sb'O^ 292 Antimonic acid Sb 162 Sb^Qs 324 Arsenious acid As 99 As^QS 198 Arsenic acid As 115 As^O^ 230 Baryta - - . Ba 76-5 BaO 153 Bismuth peroxide Bi 232 Bi^O' 464 Boracic acid B 35 B^O' 70 Carbonic acid - 0 22 C02 44 Cerium protoxide Ce 54 CeO 108 Chromium oxide Or 76-5 153 Chromic acid - Cr 50-25 CrO^ 100-5 Cobalt protoxide Co 38 CoO 76 Copper suboxide eu 71-4 Cu'O 142-8 „ ' protoxide Cu 39-7 CuO 79-4 Glucina - Gl 12-8 GIO 25-4 Iron protoxide - Fe 36 FeO 72 „ peroxide - ^e 80 Fe'O' 160 Lead protoxide Pb 111-5 PbO 223 Lime or Calcia Ca 28 CaO 56 80 OXYGEN COMPOUNDS. TABLE II. — Binary Compounds with Oxygen — continued. Ncinie. Old Atoms. New Atoms. Lithia - - - f ,1 1 ^ LO ±JL \J SO Magnesia Mo* iVlg 90 4-0 Manganese protoxide ±¥±11 00 O ±v±iiv/ 71 1 ± peroxide jjfin 1 o ±V±li \J XU\J Molybdic acid - Mo 72 MoO'"^ 144 Nickel protoxide Ni ±> 1 O 1 NiO 74 Nitric acid IN 04: i> \j ± uo Phosphoric acid 71 142 Potassa - - - K 47 KG O A Silica Si 30 SiO dU Soda - Na 31 JNaO bZ Strontia - - - Sr 52 SrO 104 Sulphuric acid s" 40 SO^ 80 Tantalic acid - Ta 222 Ta^O^ 444 Thorina - Th 131-7 ThO' 263*4 Tin peroxide Sn 74 SnO' 148 Titanic acid Ti 41 TiO' 82 Tungstic acid - W 116 WO' 232 Uranium protoxide - U 68 uo 136 J, peroxide 144 U^O' 288 Yanadic acid - Y 92-5 YO' 185 Water H 9 H'O 18 Yttria - Y 38-8 YO 77-7 Zinc oxide Zn 40-8 ZnO 81-6 Zirconia - Zr 60-8 ZrO- 121-6 Similar to the compounds of oxygen are those with sulphur, usually named sulplmrets, and considered analo- gous to the oxidised bases. A few of more electro-negative CHEMICAL COMPOUNDS. 81* character, resembling acids, have been distinguished as sulphides. Many of these combinations occur as independent species in the mineral kingdom, especially those with oxygen and sulphur. ^ Thus the most abundant of all minerals, quartz, is an oxide, and corundum is of similar nature. Many oxides of the heavy metals, as of iron, tin, copper, and antimony, are very common. Compounds with sulphur also abound, and either as sulphides, like realgar, orpiment, and stibine; or as sulphurets, like galena, argentite, and pyrite. Less frequent are haloid salts, with chlorine and fluorine, as common salt and fluor spar; and still rarer those with iodine and bromine. On the other hand, metal- lic alloys, or combinations of two metals, are far from uncommon, especially those with arsenic, tellurium, or antimony. Combinations of these binary compounds with each other are still more common, the greater number of minerals being composed of an acid and base. By far the greater number are oxygen-salts, distinguished by giving to the acid the termination ate ; thus sulphate of lead, silicate of lime, and in like manner numerous carbonates, phosphates, arseniates, aluminates. The sulphur-salts (two metals com- bined with sulphur, and again combined with each other) are next in number, and perform a most important part in the mineral kingdom. The hydrates, or combinations of an oxide with water, are also common, and much resemble the oxygen salts, the water sometimes acting as an electro- positive, at other times as an electro-negative element. Combinations of a higher order are likewise common, espe- cially the double salts, or the union of two salts into a new body ; and even these again with water, as alum and many hydrous silicates. The chemical formulae for these com- pound salts are formed by writing the signs of the simple salts with the sign of addition between them : thus dolo- mite is CaC -f MgC, or, in the new form, [CaO . CO' + MgO . CO] — i.e. carbonate of lime and carbonate of magnesia; orthoclase, Al Si' + K Si' = [AFC . 3 SiO' + G 82 DIMOEPHISM. K'O . 3 SiO'] ; and cryolite, 3 NaF + AlT', consisting of three compound atoms of fluorine and sodium united to one compound atom, consisting of three of fluorine and two of aluminium. Mere empiric formulae are also used, written thus in the above instances : — [Ca. Mg . . 0^], [Al . K . Si\ 0^], and psV . Al . F]. Influence of the Chemical Composition on the External Characters of Minerals. That the characters of the compound must in some way or other depend on those of its component elements seems, as a general proposition, to admit of no doubt. Hence it might be supposed possible, from a knowledge of the com- position of a mineral, to draw conclusions in reference to its form and other properties ; but practically this has not yet been effected. The distinction between the mineralis- ing and minerahsable, or the forming and formed, elements, lies at the foundation of all such inquiiies. Certain ele- ments in a compound apparently exert more than an equal share of influence in determining its physical properties. Thus the more important non-metallic elements, as oxygen, sulphur, chlorine, fluorine, are remarkable for the influence they exert on the chai^acter of the compound. The sul- phurets, for example, have more similarity among them- selves than the various compounds of one and the same metal T\dth the non-metalhc bodies. Still more generally it would appear that the electro-negative element in the compound is the most influential, or exerts the greatest degree of active forming power. After the non-metallic elements the brittle, easily fusible metals rank next in power; then the ductile ignoble metals; then the noble metals ; then the brittle, diflicultly fusible ; and last of all, the metals of the earths and alkalies. Generally each chemical substance crystallises only in one form or series of forms. Some substances, however, show dimorphism, or crystallise in two forms, and thus may compose two or more minerals. Thus sulphur, which usu- ally crystallises in the rhombic system, when melted may ISOMOEPHISM. 83 form monoclinic crystals. Carbon in one form is the dia- mond, in another graphite ; carbonate of lime appears as calc-spar or arragonite ; the bisulphuret of iron as pyrite and marcasite. An example of trimorphism occurs in the titanic acid, forming the three distinct species, anatase, rutile, and brookite. It is curious that of dimorphic min- erals one form is almost always rhombic ; thus — Cyanite, Triclinic Calc-spar, Hex. Susannite, Hex. E. - Anatase / Pyrolusite, Ehom. Cuprite, Tess. Senarmontite, Tess. - Pyrite, Tess. - Kammelsbergite, Tess. Argentite, Tess. Freieslebenite, Monocl Sulphur, Monocl. Even the temperature at which a substance crystallises influences its forms, and so far its composition, as seen in arragonite, Glauber salt, natron, and borax. Still more important is the doctrine of isomorphism, designating the fact that two or more simple or compound substances crystallise in one and the same form ; or often in forms which, though not identical, yet approximate very closely. This similarity of form is generally combined with a similarity in other physical and in chemical proper- ties. Among minerals that crystallise in the tesseral system, isomorphism is of course common and perfect, there being no diversity in the dimensions of the primary form ; but for this very reason it is often of less interest. It is of more importance among crystals of the other systems, the various series of which are separated from each other by differences in the proportion of the primary form. In Ehombic form. Sillimanite. Andalusite. Arragonite. Leadhillite. Brookite. Polianite. Chalcotrichite. Valentinite. Marcasite. Chloanthite. Acanthite. Diaphorite. Sulphur. 84 ISOMORPHIC SUBSTANCES. these perfect identity is seldom observed, but only very great similarity. The more important isomorphic substances are either simple substances, as (1) fluorine and chlorine; (2) sulphur and selenium ; (3) arsenic, antimony, tellurium ; (4) cobalt, iron, nickel ; (5) copper, silver, quicksilver, gold (1) ; or combinations with oxygen, as (6) lime, magnesia, potassa, soda, and the protoxides of iron, manganese, zinc, nickel, cobalt ; (7) lime, baryta, strontia, lead-oxide ; (8) alumina, and the peroxides of iron, manganese, chromium ; (9) phos- phoric acid, arsenic acid; (10) sulphuric, selenic, chromic acids; or combinations with sulphur, as (11) sulphuret of iron and of zinc; (12) sulphuret of antimony and of arsenic ; (13) sulphuret of copper and of silver. These substances are named vicarious, from the singular property that in chemical compounds they can mutually replace each other in indefinite proportions, and very often without producing any important change in the form or other physical properties. But there are numerous instances among the silicates, where the mutual replacement of the isomorphic bodies, especially when the oxides of the heavy metals come in the room of the earths and alkalies, exerts a most essential influence on the external aspect of the species, particularly in regard to colour, specific gravity, and transparency. The varieties of hornblende, augite, garnet, epidote, and many other minerals, are remarkable proofs of this influence. This intermixture of isomorphic elements confers many valuable properties on minerals, and to it this department of nature owes much of its variety and beauty. Without the occasional presence of the colour- ing substances, especially the oxides of iron and manganese, the non-metallic combinations would have exhibited a very monotonous aspect. It is also remarkable that in some siUcates the substitution of a certain portion of the metallic oxides for the earthy bases seems to be almost a regular occurrence ; whilst in others, as the felspars and zeolites, this rarely happens. This fact is also of great economic interest, as drawing attention to important elements often combined with others of less value. Thus iron oxide and CHEMICAL REACTION. 85 chrome oxide, sulphuret of copper and sulphuret of silver, nickel and cobalt, may be looked for in connection. The general chemical formula for such compounds is formed by writing E ( = radicle or basis) for the whole isomorphic elements ; and in special instances to place their signs either one below the other, connected by a bracket, or, as is more convenient, to inclose them in brackets one after the other, separated by a comma. Thus the general sign for the garnet is Si' + fi Si, which, when fully expressed, becomes (Ca^ ^e^ Mn^) Sf + (Al, ¥e) Si, and the mineral forms many varieties as the one or other element prepon- derates. Chemical Reaction of Minerals. The object of the chemical examination of minerals is the discovery of those elementary substances of which they consist. This examination is named qualitative when the nature of the elements alone, quantitative when also their relative amount, is sought to be determined. Mineralogists are, in general, content with such an examination as will discover the more important elements, and which can be carried on with simple apparatus, and small quantities of the substance investigated. The indications thus fur- nished of the true character of the mineral are, however, frequently of high importance. Two methods of testing minerals are employed, the one by heat chiefly applied through the blowpipe, the second by acids and other re- agents in solution. Use of the Blowpipe. The blowpipe in its simplest form is merely a conical tube of brass or other metal, curved round at the smaller extremity, and terminating in a minute circular aperture not larger than a fine needle. Other forms have been proposed, one of the most useful being a cone of tin open for the application of the mouth at the smaller end, and with a brass or platina beak projecting from the side near the other or broad end. With this instrument a stream of 86 BLOWPIPE. air is conveyed from the moutli to the flame of a lamp or candle, so that this can be turned aside, concentrated, and directed upon any small object. The flame thus acted on consists of two parts — the one nearest the beak of the blowpipe forming a blue obscure cone, the other external to this being of a shining yellow or reddish-yellow colour. The blue cone consists of the inflammable gases not yet fully incandescent, and the greatest heat is just beyond its point, where this is fully efi"ected. The blue flame still needs oxygen for its support, and consequently tends to withdraw it from any body placed within its influence, and is named the reducing flame. At the extremity of the yellow cone, on the other hand, the whole gases being con- sumed, and the external air having free access, bodies are combined with oxygen, and this part is named the oxi- dating flame. Their action being so distinct, it is of great importance to learn to distinguish accurately these two portions of the flame. This is best done by experimenting on a piece of metallic tin, which can only be kept pure in a good reducing flame, and acquires a white crust when acted on by the oxidating flame. The portion of the mineral to be examined should not be larger than a peppercorn, or a fine splinter a line or two long. It is supported in the flame either by a pair of fine pincers pointed with platinum, or on slips of platinum-foil, or on charcoal. Platinum is best for the siliceous minerals, whereas for metallic substances charcoal must be employed. For this purpose solid uniform pieces are chosen, and a small cavity formed in the surface, in which the mineral to be tested can be deposited. In examining a mineral by heat, it should be first tested alone, and then with various reagents. When placed alone in a matrass or tube of glass closed at one end, and heated over a spirit lamp, water or other volatile ingredients, as mercury, arsenic, tellurium, often sulphur, may readily be detected, being deposited in the cooler part of the tube, or, like fluorine, acting on the glass. It may next be tried in an open tube of glass, through which a current of air passes, more or less strong, according to the inclination at which REAGENTS. 87 the tube is held, so that volatile oxides or acids may be formed ; and in this way the chief combinations of sulphur, selenium, tellurium, and arsenic, are detected. On charcoal, in the reducing flame, arsenic, and in the oxidating flame, selenium or sulphur, are shown by their peculiar odour ; antimony, zinc, lead, and bismuth leave a mark or coloured ring on the charcoal ; and other oxides and sulphurets are reduced to the pure metal. On charcoal or in the platinum pincers the fusibility of minerals is tested, and some other phenomena should be observed — as whether they intumesce (bubble up), effervesce, give out fumes, become shining, or impart a colour to the flame. The colour is seen when the assay is heated at the point of the inner flame, and is — Reddish-yellow, from soda and its salts ; Violet, from potash and most of its salts ; Red, from lithia, strontia, and lime ; Green, from baryta, phosphoric acid, boracic acid, molybdic acid, copper oxide, and tellurium oxide ; Blue, from chloride of copper, bromide of copper, selenium, arsenic, antimony and lead. The fusibility, or ease with which a mineral is melted, should also be observed; and is expressed by stating whether it is easy or difficult, and takes place in large or small grains, in fine splinters, or -only on sharp angles. The result or product of fusion also yields important characters, being in some eases a glass, clear, opaque, -or coloured ; in others an enamel, or a mere slag. The most important reagents for testing minerals with the blowpipe are the following : — (1.) Soda (the carbonate), acting as a flux for quartz and many silicates, and especially for reducing the metallic oxides. For the latter purpose, the assay (or mineral to be tried) is reduced to powder, kneaded up with moist soda into a small ball, and placed in a cavity of the charcoal. Very often both the soda and assay sink into the charcoal, but by continuing the opera- tion they either again appear on the surface, or, when it is completed, the charcoal containing the mass is finely pounded and washed away with water, when the reduced metal is found in the bottom of the vessel. (2.) Borax (biborate of soda) serves as a flux for many minerals, which 88 SOLUBILITY OF MINERALS. are best fused in small splinters on platina wire. The borax when first exposed to the fiame swells up or in- tumesces greatly, and it should therefore be first melted into a small bead, in which the assay is placed. During the process the student should observe whether the assay melts easily or difficultly, with or without eff*ervescence, what colour it imparts to the product both when warm and when cold, and also the effect both of the oxidating and reducing flames. (3.) Microcosmic salt, or salt of phos- phorus (phosphate of soda and ammonia) is specially im- portant as a test for metallic oxides, which exhibit far more decided colours with it than with borax. It is also a useful reagent for many silicates, whose silica is separated from the base and remains undissolved in the melted salt. (4.) Solution of cobalt (nitrate of cobalt dissolved in water), or dry oxalate of cobalt, serve as tests of alumina, magnesia, and zinc oxide. In examining minerals in the moist way, the first point to be considered is their solubility, of which three degrees may be noted : (1) minerals soluble in water ; (2) minerals soluble in hydrochloric or nitric acid ; and (3) those un- affected by any of these fluids. The minerals soluble in water are either acids (almost only the boracic acid or sassolin and the arsenious acid), or oxygen and haloid salts. These are easily tested, one part of the solution being em- ployed to find the electro-positive element or basis, the other the electro-negative or acid. Minerals insoluble in water may next be tested with the above acids ; the nitric acid being preferable when it is probable, from the aspect of the mineral or its conduct before the blowpipe, that it contains an alloy, a sulphuret, or arseniate of some metal. In this manner the carbonic, phosphoric, arsenic, and chromic acid salts, many hydrous and anhydrous silicates, many sulphurets, arseniates, and other metallic compounds, are dissolved, so that further tests may be employed. The minerals insoluble either in water or these acids are sulphur, graphite, cinnabar, some metallic oxides, some sulphates, and compounds with chlorine and fluorine, and KEACTION OF ELEMENTS. 89 especially quartz, and various silicates. For many of these no test is required, or those furnished by the blowpipe are sufficient. The silicates and others may be fused with four times their weight of anhydrous carbonate of soda when they are rendered soluble, so that further tests may be applied. Chemical Reaction of the more Important Elements, It is not intended in this place to describe the whole of those marks^by which the chemist can detect the various elements. Our object is limited principally to the conduct of minerals before the blowpipe, and to a few simple tests by which their more important constituents may be discovered. I. — NON-METALLIC ELEMENTS, AND THEIR COMBINATIONS WITH OXYGEN. Nitric Acid is not abundant in minerals. Most of its salts detonate when heated on charcoal. In the closed tube they form nitrous acid, easily known by its orange colour and smell ; clearly exhibited when the salt is mixed with copper filings and treated with concentrated sulphuric acid. Sulphur and its compounds, in the glass tube or on charcoal, form sulphurous acid, easily known by its smell. The minutest amount of sulphur or sulphuric acid may be detected by melting the pulverised assay with two parts soda and one part borax, and placing the bead moistened with water on a plate of clean silver (or a coin), which is then stained brown or black. Phosphoric Acid. — Most combinations with this acid tinge the blowpipe flame green, especially if previously moistened with sulphuric acid. When the experiment is performed in the dark, even three per cent of the acid may be detected. Selenium and Selenic Acid are readily detected by the strong smell of decayed horse-radish, and leave a grey de- posit with a metalHc lustre on the charcoal. In the glass tube selenium sublimes with a red colour. 90 EEACTION OF ELEMENTS. Chlorine and its salts. When oxide of copper is melted with salt of phosphorus into a very dark-green bead, and an assay containing chlorine fused with this, the flame is tinged of a beautiful reddish-blue colour. Iodine and its salts, treated like chlorine, impart a very beautiful bright-green colour to the flame ; and heated in the closed tube with sulphate of potassa, yield violet- coloured vapours. Bromime and its salts, treated in the same manner with salt of phosphorus and oxide of copper, colour the blow- pipe flame greenish-blue. Both it and iodine are rare in minerals. Fluorine is shown by heating the assay mth sulphate of potassa in a closed tube with a strip of logwood paper in the open end. The paper becomes" straw-yellow, and the glass is corroded. Boracic Acid. — The mineral alone, or moistened with sulphuric acid when fusing, colours the flame momentarily green. If the assay be heated with sulphuric acid^ and alcohol added, and set on fire, the flame is coloured green from the vapours of the boracic acid. Carbon, pulverised and heated with saltpetre, detonates, leaving carbonate of potassa. Carbonic acid is not easily discovered with the blowpipe, but the minerals containing it eff'ervesce in hydrochloric acid, and the colourless gas that escapes renders litmus paper red. In solution it forms a precipitate with lime-water, which is again dissolved with efi'ervescence in acids. Silica, before the blowpipe, alone is unchanged ; is very slowly acted on by borax, very little by salt of phosphorus, but with soda melts entirely with a brisk efi'ervescence into a clear glass. The silicates are decomposed by salt of phosphorus, the silica being left in the bead as a powder or a skeleton. Most of them melt with soda to a transparent glass. Some silicates are dissolved in hydrochloric acid, and this the more readily the more powerful the basis, the less proportion of silica, and the greater the amount of water they contain. EEACTION OF ELEMENTS. 91 11. THE ALKALIES AND EARTHS. Ammonia, heated with soda in a closed tube, is readily known by its smell. Its salts, heated with solution of potassa, also yield the vapour, known from its smell, its action on turmeric paper, and the white fumes that rise from a glass tube dipped in hydrochloric acid and held over it. Soda imparts a reddish-yellow colour to the external flame when the assay is fused or kept at a strong red heat. Lithia is best recognised by the beautiful carmine red colour it imparts to the flame during the fusion of a mineral containing it in considerable amount. Where the propor- tion is small, the colour appears if the assay be mixed with 1 part fluor spar and 1 \ part sulphate of potassa. Fotassa gives a violet colour to the external cone when the assay is heated at the extremity of the oxidating flame. The presence of lithia or soda, however, disturbs this reac- tion. It may still be discovered by melting the assay in borax glass coloured brown by nickel oxide, which is changed to blue by the potassa. Baryta, strongly heated at the point of the blue flame, imparts a green tinge to the outer flame. Strontia and its salts colour the flame carmine red. Lime and its salts colour the flame yellowish-red ; the colour weakest in its compounds with sulphuric acid and silica. The colour is most distinct in the sulphates of lime, baryta, and strontia, when the assay is first heated on char- coal and moistened with hydrochloric acid. The solutions of strontia and lime in hydrochloric acid impart their colours to the flames of alcohol. Magnesia, ignited with solution of cobalt, or the oxalate of cobalt, forms a light-red mass ; but the alkalies, earths, and metallic oxides more or less interfere with this test. Alumina alone is infusible. In many combinations, when ignited with solution of cobalt, it assumes a fine 92 EEACTION OF ELEMENTS. blue colour, but iron peroxide or the alkalies interfere with the reaction. Glucina, Yttria, Zirmiia, and Thorina are not properly distinguished by blowpipe tests, though the minerals in which they occur are well marked in this way. III. — THE METALS. Arsenic on charcoal yields fumes with a smell like garlic, and sublimes in the closed tube. Most of its alloys in the reducing flame leave a white deposit on the char- coal, and some also yield metallic arsenic in the closed tube. Antimony melts easily on charcoal, emitting dense white fumes, and leaving a ring of white crystalhne oxide on the support. Antimony oxide on charcoal melts easily, fumes, and is reduced, colouring the flame pale greenish- blue. Bismuth melts easily, fumes, and leaves a yellow oxide on the charcoal. Its oxides are easily reduced, and the bead left is known by its brittleness. Tellurium fumes on charcoal, and becomes surrounded by a white mark with a reddish border, which, when the reducing flame is turned on it, disappears wdth a bluish- green light. Its combinations, heated in concentrated sul- phuric acid, colour it red. Mercury in all its combinations is volatile, and yields a metallic sublimate when heated alone, or with tin or soda in the closed tube. Zinc^ when heated with soda on charcoal, forms a deposit, which, when warm, is yellow ; when cold, white ; is tinged of a fine green by solution of cobalt, and is not further volatile in the oxidating flame. Tin forms a white deposit on the charcoal behind the assay, which takes a bluish-green colour with the solution of cobalt. The oxide is easily reduced by soda. Lead colours the flame pale blue, and forms a yellow deposit with a white border on the charcoal when heated in the oxidating flame, and with soda is easily reduced. EEACTION OF ELEMENTS. 93 Cadmium produces, with soda, a reddish-brown or orange-yellow ring, with iridescent border on the charcoal, and also on platinum-foil. Manganese alone, melted with borax or salt of phos- phorus on the platinum wire in the oxidating flame, forms a fine amethystine glass, which becomes colourless in the reducing flame. In combination with other metals, the pulverised assay mixed with two or three times as much soda, and melted in the oxidating flame on platinum-foil, forms a bluish-green glass. Cobalt, melted with borax in the oxidating flame, gives a beautiful blue glass. Minerals of metallic aspect must be first roasted on charcoal. The salts of protoxide of cobalt form bright-red solutions, from which potassa throws down a blue flaky hydrate, which becomes olive-green in the air. Nickel, the assay, first roasted in the open tube and on charcoal, produces in the oxidating flame, with borax, a glass, which, hot, is reddish or violet-brown ; when cold, yellowish or dark red; and by -the addition of saltpetre changes to blue. In the reducing flame the glass appears grey. The salts in solution have a bright-green colour, and with potassa form a green precipitate, which is un- changed in the air. Copper (the assay, if apparently metallic, first roasted) forms with borax or salt of phosphorus in the oxidating flame, an opaque reddish-brown glass, a small addition of tin aiding in the result. In the reducing flame the glass, when warm, is green ; when cold, blue. With soda metal- lic copper is produced. A small proportion of copper may often be detected by heating the assay, moistened with hydrochloric acid, in the oxidating flame, which is then tinged of a beautiful green colour. Silver from many combinations is readily extracted on charcoal with soda as a white malleable bead. From its solution in nitric acid silver is thrown down by hydro- chloric acid as a white chloride, which in the light soon becomes black. Gold is easily separated from its combinations with 94 REACTION OF ELEMENTS. tellurium on charcoal. The bead, if pure, is insoluble in nitric or hydrochloric acids. If the grain is white, it con- tains more silver than gold, and must then be heated in a porcelain capsule with nitric acid, which gives it a black colour, and gradually removes the silver, if the gold is only a fourth part or less. If the proportion of gold is greater, the nitro-chloric acid must be used, which then removes the gold. From its solution in this acid the protochloride of tin throws down a purple precipitate {imr^U of Cassius), and the sulphate of iron, metallic gold. Platinum, and the metals usually found with it, cannot be separated from each other by heat. Only the Osmium- iridium strongly heated in the closed tube with saltpetre is decomposed, forming osmium acid, known from its peculiar pungent odour. The usual mixture of platinum grains is soluble in nitro-chloric acid, leaving osmium-iridium. From this solution the platinum is thrown down by sal-ammonia as a double chloride of platinum and ammonium. From the solution evaporated, and again diluted, with cyanide of mercury, the p)(^^^^dium separates as cyanide of palladium. The rhodium may be separated by its property of combin- ing with fused bisulphate of potassa, which is not the case with platinum or iridium. Cerium, when no iron-oxide is present, produces, with borax and salt of phosphorus, in the oxidating flame, a red or dark-yellow glass, which becomes very pale when cold, and colourless in the reducing flame. Lanthanium oxide forms a white colourless glass ; didymium a dark amethyst- ine glass. Iron, the peroxide and hydrated peroxide, become black and magnetic before the blowpipe, and form, with borax or salt of phosphorus, in the oxidating flame, a dark-red glass, becoming bright-yellow when cold ; and in the reducing flame, especially on adding tin, an olive-green or mountain- green glass. The peroxide colours a bead of borax con- taining copper oxide bluish-green ; the protoxide produces red spots. Salts of protoxide of iron form a green solu- tion, from which potassa or ammonia throws down the pro- toxide as a hydrate, which is first white, then dirty-green, EEACTION OF ELEMENTS. 95 and finally yellowish-brown. Carbonate of lime produces no precipitate. The salts of the peroxide, on the other hand, form yellow solutions from which the peroxide is thrown down by potassa or ammonia as a flaky-brown hydrate. Carbonate of lime also causes a precipitate. Chromium forms, with borax or salt of phosphorus, a glass, fine emerald-green when cold, though when hot often yellowish or reddish. Its solutions are usually green, and the metal is thrown down by potassa as a bluish-green hydrate, ^ again dissolved in excess of the alkali. The chrome in many minerals is very certainly discovered by melting the assay with three times its bulk of saltpetre, which, dissolved in water, gives with acetate of lead a yellow precipitate. Vanadium, melted on platinum wire with borax or salt of phosphorus, gives a fine green glass in the reducing flame, which becomes yellow or brown in the oxidating flame, distinguishing it from chrome. Uranium, with salt of phosphorus, forms in the oxidat- ing flame a clear yellow, in the reducing flame a fine green, glass. With borax its reaction is similar to that of iron. Molybdenum forms in the reducing flame, with salt of phosphorus, a green, with borax a brown, glass. Tungsten or Wolfram forms, with salt of phosphorus, in the oxidating flame, a colourless or yellow, in the reducing flame a very beautiful blue, glass, which appears green when warm. When accompanied by iron the glass is blood-red, not blue. Tantalium, as tantalic acid, is readily dissolved by salt of phosphorus, and in large quantity into a colourless glass, which does not become opaque in cooling, and does not acquire a blue colour from solution of cobalt. Or fuse the assay with two times as much saltpetre, and three times as much soda, in a platinum spoon ; dissolve this, filter and decompose the fluid by hydrochloric acid ; the tantalic acid separates as a white powder, which does not become yellow when heated. Titanium in anatase, rutile, brookite, and titanite, is shown by the assay forming, with salt of phosphorus, in the 96 REACTION OF ELEMENTS. oxidating flame, a glass which is and remains colourless ; in the reducing flame, a glass which appears yellow when hot, and whilst cooling, passes through red into a beautiful violet. When iron is present, however, the glass is blood- red, but is changed to violet by adding tin. When titanate of iron is dissolved in hydrochloric acid, and the solution boiled with a little tin, it acquires a violet colour from the oxide of titanium. Heated with concentrated sulphuric acid, the titanate of iron produces a blue colour. CLASSIFICATION OF MINERALS. 97 CHAPTER IV. CLASSIFICATION OF MINERALS. A MINERAL species was formerly defined as a natural inorganic body, possessing a definite chemical composition and peculiar external form. The account given of these properties shows that the form of a mineral species com- prehends not only the primary or fundamental figure, but all those that may be derived from it by the laws of crys- tallography. Irregularities of form arising from accidental causes, or that absence of form which results from the limited space in which the mineral has been produced, do not destroy the identity of the species. Even amorphous masses, when the chemical composition remains unaltered, are properly classed under the same species as the crystalline. The definite chemical composition of mineral species must be taken with equal latitude. Pure substances, such as they are described in works on chemistry, are very rare in the mineral kingdom. In the most transparent quartz crystals, traces of alumina and iron oxide can be detected ; the purest spinel contains a small amount of silica, and the most brilliant diamond, consujned by the solar rays, leaves some ash behind. Such non-essential mixtures must be neglected, or each individual crystal would form a distinct mineral species. The isomorphous elements introduce a wider range of varieties, and render the limitation of species more difficult. Carbonate of lime, for instance, becomes mixed with carbonate of magnesia or of iron in almost innumerable proportions; and the latter substances also with the former. Where these mixtures are small in amount, variable in different specimens, and do not sensibly aff'ect the form or physical characters, they may be neglected, and the mineral reckoned to that species with which it H 98 CLASSIFICATION OF MINERALS. most closely agrees. Where, however, the two substances are frequently found in definite chemical proportions, these compounds must be considered as distinct species, especially when they also show differences in form and other external characters. . . Amorphous minerals with definite composition must also be considered as true species. But when they show no definite composition, like many substances classed as clays and ochres, they cannot be accounted true minerals. Some of them, however, from their importance in the arts, others from other circumstances, have received distinct names and a kind of prescriptive right to a place in mine- ralogical works, from which they can now scarcely be banished. Many of them are properly rocks, or indefinite combinations of two or more minerals; others are the mere products of the decomposition of such bodies. In collecting the species into higher groups, and arrang- ing them in a system, several methods have been pursued. Some, like Mohs, have looked only at the external charac- ters, and asserted that they alone were sufficient for all the purposes of arranging and classifying minerals. Others, led by Berzelius, have, on the contrary, taken chemistry as the foundation of mineralogy, and classed the species by their composition, without reference to form or physical characters. Neither system can be exclusively adopted, and a na- tural classification of minerals should take into account all their characters, and that in proportion to their relative importance. Among these the chemical composition un- doubtedly holds a high rank, as being that on which the other properties will probably be ultimately found to de- pend. Next in order is their crystalline form, especially as exhibited in cleavage ; and then the physical characters,^ gravity, hardness, and tenacity. But the properties of minerals are as yet far from showing that subordination and co-relation which has been observed in the organic world, where the external forms and structures have a direct reference to the functions of the living being. Hence, even when all the characters are taken into account, CLASSIFICATION OF MINERALS. 99 there is not that facility in classifying the mineral that is presented by the other kingdoms of nature. Many, or rather most, of the species stand so isolated that it is scarcely possible to find any general principle on which to collect them into larger groups, especially such groups as, like the natural families of plants and animals, present important features of general resemblance, and admit of being de- scribed by common characteristics. Certain groups of species are indeed united by such evident characters, that they are found together in almost every method ; but other species are not thus united, and the general order of arrangement is very uncertain. Hence, though some classifications of very considerable merit have been proposed, no natural system of minerals commanding general assent has yet appeared. The arrangement followed in this treatise is chiefly founded on that proposed by Professor Weiss of Berlin. We have, however, made considerable changes, which the progress of the science and the more accurate knowledge of many species require. This classification appears to us to come nearer than any other we have seen to a natural system^ which in arranging and combining objects takes account of all their characters, and assigns them their place, from a due consideration of their whole nature, and is thus distinguished from artificial systems, which classify objects with reference only to one character. Besides species, two higher grades in classification seem sufficient at once to exhibit the natural relations, and to facilitate an easy and complete review of the species com- posing the mineral kingdom. These are families and orders. In forming the families, those minerals are first selected which occupy the more important place in the composition of rocks, and consequently in the crust of the globe. Thus quartz, felspar, mica, hornblende, garnet, among siliceous minerals ; calc-spar, gypsum, rock-salt, less so tiuor spar and heavy spar, among those of saline com- position stand out prominently as the natural centres or representatives of so many distinct families. To these certain metaUic minerals, as iron pyrites, lead-glance or 100 CLASSIFICATION OF MINEEALS. galena, blende, magnetite, the sparry iron ore or siderite, and a few more, are readily associated as important families. But the minerals thus geologically distinguished are not sufficient to divide the whole mineral kingdom into con- venient sections, and additional groups must be selected from the peculiarity of their natural -historical or chemical . properties. Thus the zeolites are easily seen to form such a natural group. The precious stones or gems ^ also, not- withstanding their diverse chemical composition, must ever appear a highly natural family, when regarded as individual objects. Their great hardness, tenacity, ^ high specific gravity without the metallic aspect, their brilliant lustre, transparent purity, and vivid colours, — all mark them out as a peculiar group. Only the diamond, which might naturally seem to take the chief place in this class, differs so much, not only in elementary composition, but in physical properties, that it must be assigned to a diverse place. Eound these species thus selected the other less impor- tant minerals are arranged in groups or families. It is evident that no precise definition of these famihes can be given, as the connection is one of resemblance in many points, not of identity in any single character. In other words, it is a classification rather according to types than from definitions, as every true natural classification must be. The same cause, however, leaves the extent of the families somewhat undefined, and also permits considerable license in the arrangement of species. But both circum- stances are rather of advantage in the present state of the science, as allowing more freedom in the grouping of species than could be obtained in a more rigid system of classification. In collecting the families into orders, the guidance of chemistry is followed rather than of natural history, though the latter is also taken into consideration. Chemical names are assigned to the orders, but still regarded as names de- rived from the prevailing chemical characters, and not as definitions. Hence it must not be considered an error should two or three mineral species be found in an order with whose name, viewed as a definition, they may not agree. OKDEES AND FAMILIES. 101 Guided by these and similar considerations, minerals may be divided into the following orders and families : — Oeder I. — The Oxidised Stones. Fciii lilies ; 1, Quartz. 8. Serpentine. 2. Felspar. 9. Hornblende. 3. Scapolite. 10. Clays. 4. Haloid stones. 11. Garnet. 5. Leucite. 12. Cyanite. 6. Zeolite. 13. Gems. 7. Mica. 14. Metallic stones. Order II.- —Saline Stones. Families 1. Calc spar. 4. Gypsum. 2. Fluor spar. 5. Rock salt. Q O. Heavy spar, Order III.— Saline Ores. Families . •— 1. Sparry iron ores. 3. Copper salts. 2. Iron salts. 4. Lead salts. Order IV.- —Oxidised Ores. Families . :— 1. Iron ores. 4. Red copper ores. 2. Tinstone. 5. White antimony 3. Manganese ores. Order V.— -Native Metals. Form only one family. Order VI. — Sulphuretted Metals. Families:—!. Iron pyrites. 4. Gray copper ore. 2. Galena. 5. Blende. 3. Gray antimony ore. 6. Ruby-blende. Order VII. — The Inflammables. Families:—!. Sulphur. 4. Mineral resins. 2. Diamond. 5. Combustible salts. 3. Coal. In describing the species we have followed this general DESCRIPTION OF SPECIES. plan. First, that name which it seems most expedient to adopt is given, with the principal synonyms, followed in the same line by the probable chemical formula. The new formulae are also, as stated, given for the more important species, and distinguished by being enclosed in brackets [thus]. In the descriptions the system of crystallisation is noted, and the mineral more precisely characterised by enumerating some of its more common forms and combina- tions with their characteristic angles. The physical cha- racters of the species, its state of aggregation, cleavage, fracture, hardness (H.), and specific gravity (G.), follow; then its lustre, pellucidity, colour, and any other marked peculiarities. Next come its chemical characters, or its conduct before the blowpipe (B.B.), and the effect of acids, specially the hydrochloric (A.), nitric (^.), and sulphuric (s.). The chemical composition, or the amount of the different elements in 100 parts, generally deduced from the formula, but with notices of the more important variations indicated by the best analyses either from the substitution of isomor- phous elements or other substances, are then noted. The principal localities where each species occurs, especially in our own country, with certain miscellaneous particulars, conclude the description. We have also given characters of the orders and families, so far as possible. These, of course, apply chiefly to the more important and better marked or typical species (indicated by one or two asterisks [* or **] prefixed to the name), but in most points are also descriptive of the others. Tlie possibility of forming such general characters is the best proof that the groups are so far natural, and that the object of a scientific classification has been partially at least attained. 4 PAKT IL DESCEIPTION OF MINEEAL SPECIES. Order L— THE OXYDISED STONES. The minerals contained in this order are either simple oxides or compounds of oxides. The earths and alkalies compose the greater number, whilst oxides of the true metals are not abundant, and occur generally as isomor- phous with or replacing them. SiUca almost always occurs as the acid element, but in a very few alumina appears to take its place. They are not soluble in water (or in very minute amount). They have all a stony aspect, non-me- taUic lustre, and most of them are white or colourless, and more or less translucent, except the metallic stones. All translucent stones that do not scratch with the knife (except boracite and diamond) belong to this order. **Family I. — Quartz. Characters of family chiefly those of the first species. Silica usually occurs either crystalline with G. = 2*6, or amorphous with G. = 2*2 ; but a third form crystalline and with G. = 2*3, is also known. Generally it is insoluble in water or acids, but in certain conditions, as when sepa- rating from decomposing silicates, it is soluble, and hence found in springs and rivers, and more abundant in hot springs. It is then of great importance in many organic and inorganic processes. Quartz is the true type or repre- sentative of the mineral kingdom. *^1._QUARTZ.— Si - [SiO']. Hexagonal ; the purest varieties tetartohedral. The primary pyramid P has the middle edge = 103° 34', and the QUAETZ. [Quartz polar edges = 133° 44', and is often perfect. Very fre- Ciuently it appears as a rhomboliedron E (or J P), with polar edges = 94'' 15'. Crystals often of r.P . P : ocP . P . 4P, the forms ocP and 4P being combined in an oscillatory man- ner, producins: strife on the face of the prism; ocP .^P. i{2P2) (v, 5) (Fig. 101), the last face appearing as a rhomb replacing the angles between the two other forms. They are prismatic, or pyramidal, or rhombohedral, when P is divided into E and - E ; the latter very often wanting. Twins or macles common, with par- allel axes, and either merely in juxtapo- sition (see Fig. 80), or interpenetrating. . The crystals occur either smgle, attached, or imbedded, or in groups and druses. Most freciuently granular, massive, fibrous, or columnar ; also in pseudomorphs, petrifactions, and other forms. Cleavage, rhombohedral along E very imperfect : prismatic along ccP still more imperfect. Frac- ture conchoidal, uneven, or splintery. H. = 7; G. = 2'5...2-8, or 2-65 in the purest varieties. Colourless, but more often white, gray, yellow, brown, red, blue, green, or even black. Lustre vitreous, inclining to resinous ; transparent or trans- lucent, when impure almost opaque. B.B. infusible alone ; with soda effervesces and melts into a clear glass. ^ In- soluble in acids, except the fluoric; when pulverised, shghtly soluble in solution of potash. Chem. com. 4 8 '05 siUciuni and 51-95 oxygen, but frequently a small amount of the oxides of iron or titanium, of lime, alumina, and other substances. Varieties are — Bock-cri/stal, highly transparent and colouriess ; Dauphine, Switzeriand, Tyrol, Hungary, Mada- gascar, and Ceylon. Arnethyst, violet-blue (from iron per- oxide or manganese), and often marked by zig-zag or undu- lating lines, and the colour disposed in clouds ; Siberia, Persia, India, Ceylon, Brazil (white or yellow named topaz), Hungary, Siebeiiburg, Iixdaii:d. near Cork, and Aberdeen- Family.'] QUARTZ. 105 shire. Wine yellow, or citrin and gold topaz ; the brown or smoky quartz (coloured by a substance containing carbon and nitrogen) ; and the black or morion ; Siberia, Bohemia, Pennsylvania, and other places. Cairngorm stone, brown or yellow j Aberdeenshire mountains. The above are valued as ornamental stones ; less so : — Eose-quartz, red inclining to violet-blue j Ben Macdhui, and Eabenstein in Bavaria. Milh quartz, milk-white, and slightly opalescent ; Greenland. Prase, leek and other shades of green ; Saxony and Cedar Mountain in South Africa. Cafs-eye, greenish-white or gray, olive-green, red, brown, or yellow ; Ceylon and Malabar. Avanturine, yel- low, red, or brown ; India, Spain, and Scotland. Siderite, indigo or Berlin blue ; Golling in Salzburg. Common quartz, crystallised or massive, white or gray, also red, brown, etc., is a frequent constituent in many rocks. Some impure varieties are properly rocks, as — (1.) Ferruginous quartz, or iron-Hint, red, yellow, or brown, often associated with iron ores. (2.) Jasper, red, yellow, brown, also green, gray, white, and black alone, or in spots, veins, and bands (Eibbon or Egyptian jasper) ; the Ural, Tuscan Apennines, the Hartz, and many parts of Scotland. (3.) Lydian stone, or flinty slate, black, gray, or white ; has a splintery or conchoidal fracture, breaks into irregular fragments, and passes by many transitions into clay-slate, of which it is often merely an altered portion, as in Scot- land ; used as a touchstone for gold, and at Elfdal manu- factured into ornaments. (4.) Hornstone or chert, compact, conchoidal splintery fracture ; translucent on the edges, and dirty gray, red, yellow, green, or brown ; passes into flint, flinty slate, or common quartz ; common in the mountain limestone, oolite, and greensand formations ; and often contains petrifactions, as shells, corals, and wood. Other siliceous minerals seem intimate mixtures of quartz and opal, as, — Flint, grayish-white, gray, or grayish- black, also yellow, red, or brown; sometimes in clouds, spots, or stripes ; semitransparent ; lustre dull ; fracture 106 TPJDrMITE. [Quartz flat conclioidal ; occurs chiefly in the chalk formation, as in England, Ireland, Aberdeenshire, France, Germany, and other countries ; sometimes in beds or vertical veins, oftener in irregular lumps or concretions, inclosing petrifac- tions, as sponges, echinoids, shells, or siliceous infusoria. The colour is partly derived from carbon or organic mat- ter. It is used for gun-flints, and for the manufacture of glass and pottery, and cut into cameos or other ornaments. Calcedomj, semitransparent or translucent ; white, gray, blue, green, yellow, or brown; stalactitic, reniform, or botryoidal, and in pseudomorphs or petrifactions ; Trevas- cus mine in Cornwall, Scotland, Hungary, Tyrol, Bohemia, Oberstein. Carnelian, chiefly blood-red, but also yellow, brown, or almost black ; India, Arabia, Surinam, and Siberia ; also Bohemia, Saxony, and Scotland (Perthshire). Plasma, leek or gi-ass green, and waxy lustre ; Olympus, Schwarzwald, India, and China. Chri/sojjrase, apple-gTeen ; Silesia, and Vermont in Xorth America. Heliotrope or llooddtone, dark-green, sprinkled with deep-red spots ; Siberia, Bohemia, the Fassa Valley, the island of Eum and other parts of Scotland. Agates, mixtures chiefly of calce- dony in layers, with jasper, amethyst, or common quartz, abound in the amygdaloids of our o^vn and other countries. O/vjx, alternate layers of white, brown, or black, was much used in ancient times for cameos. Some crystals are remarkable for their great size, as one in the Museum at Paris, measuring 3 feet in dia- meter, and weighing nearly 8 cwt. Other specimens con- tain cavities inclosing various substances, more than -40 known, as silver, iron pyrites, rutile, magnetite, tremolite, amianthus, mica, tourmeline, topaz ; also air, water, naph- tha, and fluid carbonic acid. 2. Tridymite. — Si. Hexagonal; P middle edge 124° 4', polar edges 127° 35'. Single crystals very minute hexagonal tables of OP. ooP, but with the edges replaced by P and (xP2, are rare. Mostly conjoined in macles of two, or oftener three. Cleav- age, basal indistinct ; fracture conclioidal. H. = 7 ; G. = Family,] OPAL. 107 2 -2 8 2... 2 '3 2 6. Colourless and transparent. Vitreous, pearly on the basis. B.B. like quartz. Chem. com. 96 silica, with some alumina, magnesia, and iron peroxide, probably from the matrix. Discovered by Von Rath in the trachyte of San Cristobal, near Pachucho, in Mexico. Also in the trachyte of Mont-Dore, Puy Capucine, the Drachenfels, and of Hungary. Many opals, treated with solution of potash, leave tridymite crystals, as those from Zimapan, CaschaU; Silesia, and the cacholong from Iceland. Where they are abundant, the opal becomes opaque or snow-white. Said also in meteoric iron, Breitenbach. *3. Opal.— Si, H, or Si H^. Amorphous ; fracture conchoidal ; very brittle. H. = 5*5...6'5 j G. = 2...2*2. Transparent to opaque ; vitreous, inclining to resinous. Colourless, but often white, yellow, red, brown, green, or gray, with a beautiful play of colours. B.B. decrepitates and becomes opaque, but is infusible ; in the closed tube yields water ; almost wholly soluble in solution of potash. Chem. com. silica, with 5 to 13 per cent water ; or probably a mere hardened natural gelatine of silica with water; but most are mixtures of various minerals. Varieties are — (1.) Hyalite, glassy -opal, or Muller's glass, transparent, colourless, very glassy ; small botryoidal, or incrusting ; Kaiserstuhl in the Breisgau, Schemnitz, Silesia, Moravia, Mexico, and other places. (2.) Fire-opal or girasol, transparent, brilliant vitreous lustre ; bright hyacinth red or yellow; Zimapan in Mexico, and the Faroe Islands. (3.) Noble opal, semitransparent or translucent; resinous inclining to vitreous; bluish or yellowish-white, with brilliant prismatic colours ; most show double refraction and are binaxial ; in irregular masses or veins near Eperies in Hungary. (4.) Common opal, semitransparent, vitreous ; white, yellow, green, red, or brown ; Hungary, also Faroe, Iceland, the Giant's Causeway, and the Western Isles of Scotland. (5.) Semi-opal, duller and less pellucid. JFood- opal^ or lithoxylon, with the form and texture of wood distinctly seen ; Hungary, Bohemia, and other countries. 108 EARTHY SILICA. [Felspar (6.) Menilite, compact, reniform ; opaque and brown or bluish-gray ; Mont Menil, near Paris. (7.) Opal jasper, blood red, brown, or yellow. (8.) Cacholong, opaque, dull, glimmering, or pearly, and yellowish or rarely reddish- white ; in veins or reniform and incrusting ; Faroe, Iceland, the Giant's Causeway. One variety is named Hydropliane, from imbibing water and becoming translucent. (9.) Sili- ceous sinter, deposited from the Geyser and other hot springs j and Pearl sinter, incrusting volcanic tufa at Santa- Fiora in Tuscany (Fiorite), and in Auvergne. That from the Geyser contains 84'4 silica, 3*1 alumina, 1*9 peroxide of iron, 1*1 magnesia, 0*7 lime, 0*9 potash and soda, and 7'9 water. 4. Earthy Silica. (a.) Spongiform quartz, coarse, earthy, soft, and often friable, and yellow or grayish-white ; porous, and swims on water till saturated ; St. Ouen, near Paris, (b.) Tripoli, coarse or fine earthy ; white, gray, or yellow ; near Tripoli in Africa, Corfu, Bohemia, Saxony, and Bavaria, (c.) Polish- ing slate (Polirschiefer), white or yellow ; slaty texture, opaque, brittle, and swims on water ; at Bilin in Bohemia ; consists chiefly of the siliceous remains of plants {Dia- tomacece), (d.) Adhesive slate, from Montmartre, near Paris. And (e.) Mountain meal, snow-white, pearly, gray, or green- ish ; have a similar origin ; Santa Flora in Tuscany, Oberohe in Hanover, Kymmenegard in Sweden (where used as food), in Bohemia, and the Isle of France. Family II. — Felspar. Crystallisation monoclinic or triclinic, both very similar in aspect and angles. Cleavage very distinct, especially the basal P ; less so the clino- or brachy - diagonal M, G. = 2-4. ..3-2, but mostly 2-5. ..2-8; H. = G, or a little more. Slightly or not at all soluble in acids. B.B. fusible, but often with difliculty. Translucent, pure varieties highly transparent. Colourless, white, or shades of red ] less com- mon, green or yellow. Cliem. com. anhydrous siUcates of alumina, and of an alkali or lime. Family.^ FELSPAR. 109 The felspars are very important constituents of the earth's crust, occurring in nearly all the igneous rocks, and in many of the stratified crystalline schists. In true strata they are found chiefly as fragments or decomposed, and in the latter state form a large part of most soils and clays. In the older mineralogists and popular language many species are conjoined under the common name of felspar which are now considered as distinct, each of them having not only its peculiar physical and chemical characters, but also geognostic position and associated group of minerals. Thus orthoclase, and the other more siliceous felspars with potash, abound in granite and the plutonic rocks ; the less siliceous, with soda and lime, characterise the volcanic rocks — as labradorite the basaltic group, glassy felspar the trachytic. Orthoclase is associated with quartz, hornblende, and mica ; glassy felspar either with hornblende and mica or with augite ; labradorite only with augite, rarely with quartz or hornblende. The felspars are best known from similar minerals by their hardness (scarce scratch with a good knife), difficult fusibility, and unequal cleavages. The following marks may aid the student in distinguishing the more common species. In orthoclase the basal cleavage plane forms a right angle with the clinodiagonal cleavage planes M on both hands ; in the triclinic or plagioclase felspars the angles are unequal. Orthoclase, albite, andesin, and oligo- clase are insoluble in acids ; ryacolite, labradorite, and anorthite more or less soluble. In granite, when decom- posing, orthoclase often becomes reddish or dark-red ; oligo- clase dull green, and at length white. S. von Walterhausen stated that the felspars were mix- tures of three true species, forming a series with the oxygen of the silica, alumina and "k^x: ?> :l : — x ranging from 24 to 4. Tschermak and most mineralogists now take a similar view, regarding orthoclase, albite, and anorthite alone as true species, of which the others are mixtures. Those consisting essentially of potash and soda only, are mechanical mixtures of orthoclase and albite, the distinct lamellae visible by the microscope ; those again that contain 110 ORTHOCLASE. [Felspar essentially lime and soda together, are chemical, isomorphous compounds of albite and anorthite in various proportions, and with corresponding transitions in crystallographic and physical properties. Monoclinic; (7-63° 57' ; ooP {T and /) 118° 47', P^'oo 65° 46', 2 P'^oo 90° 71', 2P^oo {y) 35° 45' ; crystals often of ooP . OP . P'oo ; or ooP^oo (ilf) . ooP . OP (P) . 2P''oo (Fig- 102), are short rhombic prisms, when ooP pre- dominates j or tabular when ooP^'oo ; or short hexagonal prismatic when ooP and ooP'^oc ; or rectangular prismatic when OP and ooP'^oo predominate j and occur single, at- tached, or in druses. Macles are frequent, especially with the twin axis parallel to the chief axis, and often partially interpenetrating, as in Fig. 103. Also massive and coarse or fine granular. Cleavage, basal (P) very perfect ; clino- diagonal (TIf) perfect (P to ilf=90°); and liemiprismatic odP in traces. Fracture conchoidal or uneven and splintery. H. = 6 ; G. = 2 '5 3... 2 '5 8. Tmnsparent to translucent on the edges ; vitreous, but often pearly on the more perfect cleavage ; and also opalescent, with bluish or changing colours. Colourless, but generally red, yellow, gray, or green. B.B. fuses with difficulty to an opaque vesicular glass ; not affected by acids. Chem. com. 64*6 silica, 18-5 **5. Orthoclase. ±\ Sf + K Si^ or [KW . 3 SiO' -i- K^O . 3 SiO^. Fig. 102. Fig. 103. Family.'] OETHOCLASE. Ill alumina, and 16*9 potash, but generally 10 to 14 potash, 1 to 4 soda, 0 to 1 -3 lime, 0 to 2 iron peroxide. Varieties are — (1.) Adularia and Ice-spar, transparent or translucent, splendent, and almost, or wholly, colourless. Some with a bluish opalescence are named Moonstone; St. Gotthardt, Mont Blanc, Dauphine, Arendal, Southern Norway, Greenland, and Ceylon. (2.) Common felspar, less splendent and transparent, and generally white or red, especially flesh-red, is a very com- mon constituent of many rocks. Crystals at Baveno on Lago Maggiore, Lomnitz in Silesia, Mourne Mountains and Wicklow in Ireland, Aberdeenshire (at Eubislaw, 4 or 5 inches long) in Scotland, and at Carlsbad and Elnbogen in Bohemia. Amazon stone, verdigris-green, from Lake Ilmen ; and Murchisonite, golden or grayish-yellow, from Arran and Dawlish, seem varieties. (3.) The Glassy felspar or Sanidine ((7=64° 1', ooP 119° 16') contains 3 to 12 potash, 3 to 10 soda, 0 to 3 lime, and 0 to 2 magnesia. Crystals imbedded, yellowish- white or gray ; vitreous ; transparent or translucent, and Macles of common Felspar RIGHT. LEFT. Fig. 104. often much cracked ; Drachenfels, Auvergne, Italy, Iceland, Mexico, and other countries; also in Arran, Eum, and other parts of Scotland. Ehyacolite, from Vesuvius and Lake Laach, is only an impure variety. Loxoclase, from Ham- 112 ALBITE. [Felspar mond, New York, also a variety with much soda. Baulite and KraUite from Iceland, probably mixtures with quartz. Orthoclase occurs in granite, gneiss, and porphyry in many countries. It is commonly associated with quartz, sometimes, as in the graphic granite of Portsoy and Aber- deenshire, in regular combinations. It is very liable to decomposition, when it is converted especially into kaolin, used for manufacturing porcelain and stoneware. The adularia or moonstone, and the green amazon stone, are cut as ornamental stones. Com2?act felspar, ot feldsfein, a mixture of orthoclase and quartz, often harder than the pure mineral. G. = 2-59...3. White, gray, red, or yellow, sometimes in spots or bands. The softer varieties, or claijstones, often bluish or purplish. G. = 2-21. B.B. most melt with difficulty to a white enamel (hornstone is infusible). Commxon in the porphyry rocks of many countries, as in Scotland (Cheviots, Pentland, and Ochil Hills), and Sweden {Leelite from Grythyttan). . ( Al Si' + Na Si', or ^' 1 [AVO\ 3SjO^ + IsVO . 3SiO^]. Triclinic; OP (P) to ooPoo (if) = 86° 24', ooF (/) to ooT (r) = 122° 15', but angles very variable. Crystals, generally like those of orthoclase, are tabular or prismatic M 1\ 5 Fig. 105. (Fig. 105). Macles very common, especially united by a face of 00 P (Fig. 106), the re-entering angle between the faces of OP (P and P') = 172° 48' being very characteristic. Fi^. 107 is another made common in pericline. Also Family.] ANDESINE. 113 massive and foliated, or radiating. Cleavage, basal and brachydiagonal almost equally perfect, prismatic along 00 P imperfect j fracture conchoidal or uneven. H. = 6... 6*5; G. = 2-6...2'67. Earely transparent, usually trans- lucent or only on the edges; vitreous, pearly on the cleavage. Colourless, but generally white, gray, green, red, or yellow ; streak white. B.B. difficultly fusible, tinging the flame yellow, to a white semi-opaque glass ; not aff'ected Fig. 106. Fig. 107. by acids. Chem. com. 68-6 silica, 19-6 alumina with 0*1 to 1 iron peroxide and 11-8 soda with 0*3 to 4 lime, 0 to 2-5 potash, and 0 to 0*5 magnesia. Hence albite and orthoclase both contain soda and potash, only in different proportions. Albite is best marked by the frequent re- entering angles, its more easy fusibility, and the obliquity (93° 36') of its cleavage planes, often marked with strise. Fericline, with G. - 2-54 ... 2'6, and slight diversity in angles, is only a variety. Albite is a constituent of many greenstones (Edinburgh), of granite (Aberdeenshire), syenite, gneiss, porphyry, and trachyte ; also in beds and veins ; crystals at Bareges in the Pyrenees, Bourg d'Oisans in Dauphine, St. Gotthardt, the Tyrol, Salzburg, and Arendal. Adinole is a compact gray or red mixture of albite and quartz. 7. Andesine.— Al Si' + (Na, Ca) Si. Triclinic; crystals and physical properties similar to albite ; but the cleavage less distinct. B.B. more easily I 114 LABRADORITE — AXOETHITE. fusible to a milky somewhat porous glass. Chem. com. 59-7 silica, 25*6 alumina, 7'7 soda and 7 lime, and thus nearly 1 albite and 1 anorthite, but some a little potash and magnesia ; and others nearer oligoclase, from which scarce distinct. Andes, Yosges, and Iceland. SaccJiarite, compact, or fine granular; white or apple- green j Silesia and Canada j also a variety. -r f ±1 Si' + (Ca. Xa) Si = Triclinic ; OP : a:Px - 86' 40^ OP : o^/P = llT. Crys- tals rare ; mostly massive and granular ; macles like those of albite (Fig. 107). Cleavage, basal very perfect; brachy- diagonal less so ; both usually striated. H. = 6 ; G-. = 2-68 ...2° 74. Translucent, or only on the edges ; vitreous, ^ on the cleavage pearly or resinous. Gray, passing into white, gi^een, yellow, or red. The faces of ccP^c often exhibit very beautiful changing colours— blue, green, yellow, red, or brown — somethnes in bands intersecting at certain angles. B.B. fuses more readily than orthoclase to a com- pact colourless glass ; soluble when pulverised in n. acid. Chem. com. 52-9" silica, 30-3 alumina with 1 to 2 iron per- oxide, 12-3 lime, and 4'5 soda with 0*3 to 2 potash, O'l to 2 magnesia, and 1 to 3 water — the latter probably not essential. It is thus = 1 albite and 3 anorthite. Common constituent of dolerite, greenstone, the gabbro, and hypersthene rocks. Labrador, Finland, Harz, Meiss- ner, Tyrol, Mourne Mountains, Campsie and Milngavie near Glasgow, and Skye ; also Etna and Vesuvius, and in meteoric stones. ^^9. Anorthite, / A1 Si + Ca Si, or Christianite. ( [^1' 0^ . Si 0' + CaO . Si 0']. Triclinic ; OP : ocPoo = 85° 50' ; ocP' : cr/P = 120° 30'. Crystals and macles like albite, with angle between F and P'==188° 24'. Cleavage, basal and brachydiagonal per- fect. H. - 6 ; G. = 2-7...2-76. Transparent or translu- cent ; vitreous. Colourless or white. B.B. fuses to a clear glass ; soluble without gelatinising in con. h. acid. Chem. Family,'] OLIGOCL A SE — PETALITE. 115 com. 43-0 silica, 36*9 alumina, and 20*1 lime with 1 to 5 magnesia, 0'3 to 8 soda, 0*2 to 1 potash, and 0*1 to 2 iron peroxide. Monte Somma, Iceland, Java. Amphodelite has the same composition and a close resem- blance in crystalline forms, cleavage, and macles ; is reddish- gray, or dirty peach-blossom red. Lojo in Finland, and Tunaberg in Sweden. Latrobite, massive or in indistinct crystals of a red colour from Amitok in Labrador, and Bolton, Massachusetts, is a similar variety with the alumina partly replaced by man- ganese peroxide. Lepolite from Lojo is similar. Bytown- ite from Canada, a mixture of anorthite and hornblende. *10. Oligoclase— 2 M Si' -f- (Na, Ca)' Sf. Triclinic ; OP : (xPoo - 86° 10' ; ooF : ooT = 120° 42'. Crystals, rather rare, and macles resemble albite. Cleavage, basal perfect ; brachydiagonal less perfect ; ooP' imperfect. H. = 6; G. 2-64.. .2-68. More or less translucent; vit- reous, pearly or resinous on the cleavage. White, with a tinge of green, gray, or red. B.B. melts easier than ortho- clase or albite to a clear glass; not affected by acids. Chem. com. 63 silica, 23-4 alumina, 8*4 soda, and 4*2 lime; but 20 to 24 alumina, 7 to 12 soda, 1 to 4 potash, 5 to 4 lime, 0 to 1 magnesia, and 0 to 4 iron peroxide. Thus nearly = 3 albite and 1 anorthite. Scandinavia, Ural, Harz, and North America. In granite near Aberdeen, and Ehiconich, Sutherlandshire. Distinguished from orthoclase by the marked striae on the faces ; less readily from albite, but more fusible, and G. higher. The Sunstone from Norway, Lake Baikal, and Ceylon, with a fine play of colour, belongs to this species. 11. Petalite, Castor.— 4 Al Si' + 3 (Li, Na) Si'. Monoclinic, castor with C. = 67° 34' and ooP 87°, in irregular rectangular prisms, or petalite massive and coarse granular. Cleavage, basal distinct, in a second direction (meet at 1411°) less so, and mere traces of a third. H. 6-5; G. = 2-4...2-5. Greenish, grayish, or reddish white, 116 SPODUMENE — POLLUX — ZYGADITE. [Felspar to pale red. Translucent ; -vitreous or pearly. B.B. melts easily into an obscure porous glass, colouring the flame red ; not affected by acids. Chem. com. 78'3 silica, 17-4 alumina, 3-2 lithia, and M soda. Utoe, Bolton in Massachusetts, York in Canada, and castor in Elba. 12. Spodumene, f 4 ^I 'Si' + 3 (Li, Na, K) Si, or Triphane. \ [4 (AF 0^ 3 Si 0^3 (Li^O . Si 0^)]. Monoclinic ; C. = 69° 40' ooP = 87° ; isomorphous with augite (diopside). Cleavage, prismatic coP, and ortho- diagonal perfect : chiefly massive or foliated. H. = 6 '5 . . . 7 ; G. 3-1... 3*2. Translucent; vitreous or pearly. Pale greenish-gray or white to apple-green ; streak white. B.B. intumesces slightly, tinging the flame momentarily purplish- red, and fuses easily to a colourless glass ; not affected by acids. Chem. com. 65-0 silica, 2 8 "7 alumina, and 6' 3 lithia, with O'l to 2*5 soda, 0 to 4-5 potash, and 0 to 1 lime. Utoe in Sweden, Tyrol, Killiney near Dublin, Peterhead in Scotland, and crystals at Norwich in Massachusetts. Killinite. — Crystalline foliated. Cleavage along a prism of 135°. H. = 4; G. = 2*65. Greenish-gray, yellow or brownish-green. B.B. melts difficultly to a white porous enamel. Chem. com. 2 ±\ Si' -f E Si' -f 3 H, in which R is potash, lime, magnesia, iron protoxide, and lithia. Killi- ney near Dublin, with spodumene. 13. Pollux.— Al Sf + R Si' + H. Tesseral ; faces of cube and icositetrahedron. Mostly massive, with mere traces of cleavage ; fracture conchoidal. H. - 5-5. ..6-5 ; G. = 2-87... 2*89. Transparent ; splendent vitreous. Colourless. B.B. melts on thin edges to an enamel-like porous glass, colouring tlie flame reddish-yellow. Soluble in warm h. acid. Chem. com. 44-03 silica, 15'97 alumina, 0*68 lime, 0-68 iron peroxide, 34-07 coesium oxide, 3*84 soda, and 2*40 water. Elba, with castor. 14. Zygadite.— Si, iVl, Li(?). Triclinic, in macles like albite. 11. - 5-5 ; G. = 2-51. Family.] AMOKPHOUS FELSPAR — PITCHSTONE. 117 Subtranslucent ; vitreous. Eeddish or yellowish white. Andreasberg. Probably a variety of albite, and no lithia. 15. Amorphous Felspar. Hyaline substances, with no regular structure, and rather rocks than minerals. "^'^(<2.) Obsidian. — Compact in globular grains or masses. Fracture conchoidal ; brittle. H. = 6. ..7 j G. = 2*2. ..2*6. Semitransparent to translucent on the edges ; vitreous. Black, gray, green, red, and brown, or striped and spotted. B.B. melts to a foamy mass, a glass or enamel. Chem. com. indeterminate, but 70 to 80 silica, 6 to 12 alumina, 3 to 10 soda, 3 to 6 potash, 1 to 7 lime, 1 to 2 magnesia, and 1 to 6 iron peroxide. Streams or detached masses near volcanoes, as Iceland, Lipari Islands, Milo, Santorin, Teneriffe, Mexico, and Hungary. Pumice. — Porous, vesicular^ or fibrous. Fracture conchoidal or flat ; very brittle. White, gray, yellow, brown, or black. H. = 5 ; G. in powder = 219... 2'2 ; in masses swims on water. B.B. melts more or less easily to a white enamel. Chem. com. like obsidian, of which it seems a peculiar state. Andernach on the Ehine, Lipari, and Ponza Islands. Used as a polishing material. (c.) Pearlstone. — Eoundish concentric globules im- bedded in a vesicular basis. Fracture conchoidal ; very brittle. H. - 6 ; G. = 2.2...2-4. Pearly. Eeddish, bluish, or ash gray ; also yellow, red, or brown in stripes or spots. B.B. melts to a white fungus-like mass. Chem. com. indefinite, or a mixture of felspar and opal, with 2 to 4 per cent water. Hungary, Siberia, Mexico. Sphcarulite, small spherical concretions in pearlstone in Hungary and Mexico, and in pitchstone in Arran and Meissen. *{d.) Pitchstone. — Compact, slaty, or in concentric scaly concretions. Fracture conchoidal ; splintery. H. - 5'5...6 ; G. = 2 -2... 2*3. Subtranslucent to opaque ; resinous. Gray, green, yellow, red, brown, black. B.B. melts to a porous glass or gray enamel. Chem. com. indefinite ; but 118 SCAPOLITE. [ScapoUte 64 to 76 silica, 11 to 14 akimina, 1 to 3 lime, 1 to 6 soda, 0 to 6 potash, 0 to 7 magnesia, 1 to 4 iron peroxide, and 5 to 9 water. Beds or veins at Tokai, Kremnitz, Schemnitz in Hungary, Meissen, Saxony, E"ewry in Ireland, and Arran in Scotland. The basis of that from Arran is, according to Zirkel, a nearly colourless glass containing crystals of quartz, felspar, and hornblende. FA]VIILY III. — SCAPOLITE. Crystallisation tetragonal or hexagonal (prehnite rhom- bic). Cleavage more or less perfect. H. = 5...6, or a little more in prehnite; G. 2 '6... 3. All fusible and soluble in acids, and gelatinise. Chem. com. anhydrous silicates of alkalies or lime, and of alumina. They are generally transparent or translucent. Colourless, but often with green or yellow tinge and resinous lustre. They resemble the felspars both in aspect and composition, and occur chiefly in volcanic or in plutonic rocks, but are rather rare. *16. SCAPOLITE, fAF Si' + 3 (Ca, Na) Si, or Wernerite. I [2 Al' 0\ 3 Si 0' + 3 (RO . Si 0')]. Tetragonal; P 63° 42^ Crystals ooPx) . P . od P, often long prismatic ; also massive and granular or colum- nar. Cleavage, ooPoo rather perfect, ooP less perfect. H. = 5...5*5; G. = 2*6.. .2'8. Transparent or translucent; vitreous, pearly, or resinous. Colourless, but pale gray, green, yellow, or red. B.B. melts with effervescence to a vesicular glass ; in the closed tube many show traces of fluorine ; with solution of cobalt become blue ; soluble in h. acid. Chem. com. about 49 silica, 28 alumina (with iron peroxide) and 23 lime (with soda) ; but analyses vary widely, and some come nearer 43 siL, 37 al., and 20 lime ; others 42 siL, 32 al, and 26 lime. The silica ranges from 40 to 60, alumina 16 to 36, iron peroxide 1 to 8, lime 3 to 24, soda to 9 and potash to 7 per cent. Arendal, Tunaberg, Pargas, Bolton in Massachusetts, and Governeur in New York. Easily known by its indistinct rectangular cleavage, the resinous lustre on fracture surfaces, and its action before blowpipe. Family.'] DIPYR — ^^NEPHELINE. 119 Meionite and Mizzonite from Somma; Nuttalite from Bolton ; Glaucolite from near Lake Baikal ; Strogonowite from the Sliidanka ; Ershyite from Pargas ; and Couzeranite from Couzeran in the Pyrenees, pitch black, blackish-blue, or gray, are only varieties. So also the Porcelain Spar or Fassauite from near Passau, which forms porcelain earth when decomposed. Barsowite. — Granular or compact, with one distinct cleavage. Translucent on the edges ; pearly. Snow-white. Gelatinises in warm h. acid, and dif. fusible. Barsowski, in Ural, is similar. 17. DiPYR.— 3 "^1 si -f 4 (Ca, Na) Si'. Tetragonal ; P 64° 4^ in rounded eight-sided prisms. Cleavage, prismatic distinct. H. = 6 j G. = 2.6...2'7. Translucent on the edges ; vitreous, whitish or reddish. B.B. becomes opaque, and melts readily to a white vesicular glass. Slightly affected by acids. Chem. com. 55*7 silica, 25*1 alumina, 9*1 lime, and 10*1 soda. Mauleon, and Castillon in the Pyrenees. *18. Nepheline, r ±\ Si -f 4 (Na, K) Si, or Elseolite. \ [AF 0\ 2 Si 0' + EO . Si 0^. Hexagonal; P 88° 10'. Crystals, ooP . OP, and ooP. OP. P {M, P, X, Fig. 108) ; embedded, or in druses ; also massive granular. Cleavage, basal and prismatic imperfect. Fracture conchoidal or uneven. H. = 5*5..,6; G. = 2*58...2'64. Transparent or translucent ; vitreous and resinous on fracture. Colourless or white (nepheline) ; or more --^ opaque, dull resinous, and green, red, or brown [| (elseolite). B.B. melts difficultly (nepheline), or easily with slight effervescence (elaeolite), into a ^ vesicular glass. Soluble and gelatinises in h. acid. Chem. com. 41*2 siHca, 35-3 alumina, 17 soda, 6*5 ^T^^os potash, with 0*2 to 2 lime, 0*5 to 1*5 iron peroxide, and under 2 water. Nepheline at Monte Somma, Capo di Bove, Katzenbuckel in the Odenwald, Aussig, and the Lau- sitz. Elaeolite in the zircon syenite at Laurvig, Fredriks- varn, Brevig, and Miask. Davine, long prismatic, J P 51° 46'. G. = 2*43. Seems 120 CANCRINITE — PREHNITE. [Scapolite only nepheline, with about 13 carbonate of lime. Vesuvius and Somma. 19. Cancrinite.— 2 (^1 Si + Na Si) + Ca C. ^ Hexagonal ; massive and columnar. Cleavage, prismatic perfect. H. = 5...5-5 ; G. = 2-42...2-46. Translucent or transparent ; resinous, on cleavage vitreous or pearly. Green, yellow, and rose-red. B.B. melts to a white vesicu- lar glass. Soluble with effervescence in h. acid. Chem. com, 2 atoms nepheline and 1 carbonate of lime, with about 36 silica, 30 alumina, 18 soda, and 15 carbonate of lime. Miask, and Litchfield in Maine. 20. Gehlenite.— (Al, ¥e) Si + (Ca, Mg, Fe)' Si. Tetragonal ; P 59°. Crystals, OP. ooPco , thick tabular or short prismatic. Cleavage, basal rather perfect, pris- matic traces. H. = 5.5...6 ; G, = 2-9. ..3-1. Translucent on the edges ; dull resinous. Mountain, leek, or olive green, to liver-brown. B.B. melts difficultly in thin fragments. Gelatinises with h. acid. Chem. com. 31*4 silica, 20 to 24 alumina, 3 to 6 iron peroxide, 35 to 38 lime, 0 to 4 magnesia, 0 to 1 '7 iron protoxide, and 1 to 3 water. Mount Monzoni in the Fassa valley. 21 . HuMBOLDTiLiTE.— (^1, Fe) Si+2 (Ca, Mg, Na, K) Si'. Tetragonal ;P65°30';0P.(X)Pqo, tabular or short prismatic. Cleavage, basal perfect. H. = 5...5'5 ; G = 2-91. ..2-95. Translucent on the edges; vitreous or resinous. Yellowish-white, honey-yellow, and yellowish- brown. B.B. melts easily to a light or blackish coloured glass. Gelatinises with h. acid. Chem. com. about 40 silica, 32 lime, 6 to 7 magnesia, 2 to 4 soda, 0*3 to 1*5 potash, 6 to 11 alumina, and 4 to 10 iron peroxide. Vesuvius and Capo di Bove. Melilite, SomervilUte, and Zurlite are identical. Sarkolite, from Vesuvius, is similar. *22. Prehnite, Si + 2 Ca Si -i- H, or Koupholite. |[ArO^ . SiO'-' + 2 (CaO ._SiO0 -f 0]. Ehombic; ooP 99° 5G', 3P oo 33° 0', fPo) 126° 40'. Crystals OP . ooP (Fig. 109), or ^P (m) . OP (P) . ooPoo (/) . Family.'] KARPHOLITE. 121 3 Poo (o) (Fig. 110), tabular or short prismatic, in druses, fan-shaped or cock's-comb groups. Also granular or spherical, reniform and fibrous. Cleavage, basal distinct, ooP imperfect. H. = 6... 7; G. = 2-8. ..3-0. Transparent or translucent on the edges ; vitreous, on OP pearly. Col ourless, but mostly greenish-white, olive, p . apple, or leek green, also yellow or reddish. When heated becomes polar- electric. B.B. melts easily, with much intumescence, to a porous enamel. Soluble in con. h. acid, but only gelatinises perfectly when pre- viously ignited or fused. Chem. com. 43*6 silica, 24-9 alumina, 271 lime, and 4*4 water (but with O'l to 7 peroxide of iron and manganese). Cape of Good Hope ; Bourg d'Oisans in Dauphine : Eatschinges and Fassa in Tyrol; Friskie Hall and Campsie, Dumbartonshire ; Hartfield Moss, Eenfrewshire ; Corstorphine Hill, the Castle Rock, and Salisbury Craigs, near Edinburgh ; Mull ; Skye ; and Dal- nabo, near Glengairn, Aberdeenshire. Frehnitoid, like prehnite, but scarce affected by h. acid. Wexio in Sweden. 23. KARPHOLITE.— Al Si + Mn Si + 2 H. Ehombic ; radiating or stellated and acicular. H = 5...5-5 ; G. ^ 2-9...3. Translucent ; silky. Straw to wax yellow. B.B. intumesces and forms an opaque brown glass. Scarcely affected by acids. Chem. com. 37 silica, 30*6 alumina, 21-6 manganese protoxide, 10-8 water, with iron protoxide and fluoric acid. Schlaggenwald and Wippra in the Harz. 24. The following are doubtful : — (a.) Kirwanite. — Spheroidal ; radiating fibrous. H. = 2 ; G. = 2-9. Opaque; dark olive-green. B.B. becomes black, and partially fuses. Chem. com. 40 5 silica, 11*14 alumina, 23-9 iron protoxide, 19-8 lime, and 4*4 water. Mourne Mountains, Ireland. 122 LAZULITE — CALAITE. [Haloid NeuroUte. — Fine columnar. H. = 4*5 ; G. = 2*47. Translucent or opaque. Greenish-yellow. B.B. infusible, but becomes snow-white and pulverulent. Chem. com. 7 3 silica, 17*4 alumina, 3-3 lime, 1*5 magnesia, and 4'3 water. Stamstead in Lower Canada. Family IV. — Haloid Stones. These minerals are so named from their resemblance to salts. Their crystallisation is rhombic or mono clinic. H. = 4. ..6 ; G. = 2-3. ..3-1. Soluble in acids. Generally infusible, or with difficulty. Most colour the B.B. flame bluish-green from phosphoric acid, being compounds of this acid with alumina, in some also with magnesia or iron pro- toxide. Are brightly-coloured minerals, of blue, green, or yellow tints. Most contain water, and do not form con- stituents of rocks. 25. Lazulite, Blue Spar.— AF P + (Mg, Fe)' P -{- 2 H. Monoclinic ; C. = 88° 2', ooP 91° 30', P 99°40;-P 100° 20'; crystals pyramidal, tabular or prismatic, but rare; usually massive or granular. Cleavage, prismatic, ooP im- perfect ; fracture uneven, splintery. H. = 5...6; G. = 3...3'1. Translucent on the edges ; vitreous. Indigo, smalt, or other shades of blue inclining to green or white ; streak white. In closed tube yields water and loses its colour. B.B. intumesces, but does not melt. With cobalt solution assumes a fine blue colour. Scarcely affected by acids till after ignition, when almost wholly soluble. Chem. com. 44' 1 phosphoric acid, 31*7 alumina, 9 to 12 magnesia, 2 to 10 iron protoxide, 1 to 4 lime, and 5 '7 water. Werfen in Salzburg, Vorau (Foraulite) and Kreiglach in Styria, Brazil, Georgia, and North Carolina. •^26. Calaite, Turquoise.— P + 5 H. Massive, reniform, or stalactitic. Fracture conchoidal. H. = 6; G. = 2*6. ..2*8. Opaque or translucent on the edges; dull or waxy. Skye-blue, greenish-blue, rarely green ; streak grcenish-wliite. In the closed tube yields water, decrepitates violently, and becomes black. B.B. in- Stones.] FISCHEKITE — WAVELLITE. 123 fusible, but colours the flame green. Soluble in acids. Chem. com. 47 alumina, 32*5 phosphoric acid, and 20*5 water, but mixed with phosphate of iron and copper. Silesia, Lausitz, andj Voigtland. Oriental turquoise, in veins, at Meschid near Herat ; in pebbles in Khorazan, Bucharia, and Syrian desert. Takes a fine polish, and is valued as an ornamental stone. Fariscite seems identical. 27. FiSCHERITE. — ±1 P + 8 H. Ehombic j ooP 118° 32', mostly in crusts or indistinct six-sided prisms. H. =^ 5; G. = 2'46. Transparent; vitreous; green. Slightly soluble in h. or n., wholly in s. acid, and on heating becomes white or partly black. Chem. com. 42 alumina, 29 phosphoric acid, 29 water, with a little lime and copper oxide. Nischnei Tagilsk. Peganite. — Probably rhombic ; ooP 127° nearly; in very small prismatic crystals or thin crusts. Emerald, grass- green, or white. H. = 3...4 ; G. = 2*49. ..2*54. Chem. com. like fischerite, but 6 H. Strigis in Saxony. BerliniU and Trolldte from Westana, and Evansite, colourless or bluish-white, from Hungary, are other phosphates of alumina with water. *28. WAVELLITE, f ±r P' + 12 H, or Lasionite. j [3 Al^ 0\ 2 PW + 1 2 0]. Rhombic;_oQP 126° 25', Poo 106° 46' ; crystals ooPqo (P) . ooP (6^) . Poo (o) (Fig. Ill) ; but generally small, acicu- lar, and in hemispherical radiated fibrous masses. Cleavage, along ooPandPoo rather perfect. H. = 3'5...4 ; G. = 2'3... 2-5. Translucent ; vitreous. Colourless, but generally yellowish or grayish, sometimes green or blue. In closed tube yields water. B.B. in the forceps colours the flame weak bluish-green ; on char- coal intumesces, and becomes snow-white. Soluble in acids. Chem. com. 38*0 alumina, 35*3 phos- Yig.iu. phoric acid, and 26*7 water; but generally traces of fluoric acid (2 per cent). Beraun in Bohemia, Amberg in Bavaria, Barnstaple in Devonshire, St. Austle in Corn- wall, near Clonmel, Cork, and Portrush, Ireland, and in 124 WAGNERITE — LEUCITE. [Leucite the Shiant Isles in Scotland ; also in New Hampshire and Tennessee. 29. Wagnerite.— Mg' P + Mg F. Monoclinic ; C. = 63° 25\ ooP 57° 35'. Cleavage, pris- matic and orthodiagonal imperfect. Fracture conchoidal or splintery. H. = 5...5'5 ; G. = 3*0... 3*2. Translucent or transparent ; resinous. Wine or honey yellow and white. B.B. fuses with great difficulty in thin splinters to a dark greenish-gray glass. Chem. com. 43*3 phosphoric acid, ir4 fluorine, 37'6 magnesia, and 7*7 magnesium; but with 3 to 4*5 iron protoxide, and 1 to 4 lime. Very rare ; Werfen in Salzburg. 30. Amblygonite.— P^ + (Li, mf P + ±1 F^ + (Li, Na) F. Triclinic ; crystals very rare, most coarse granular. Cleavage OP pearly, meeting two others at 105° and 87° 40'. Fracture uneven and splintery. H. = 6 ; G. = 3...3'1. Translucent ; vitreous. Grayish or greenish-white to pale mountain-green. In closed tube yields water, sometimes corroding the glass. B.B. fuses very readily to a trans- parent glass, opaque when cold. Finely pulverised it is slowly soluble in acids. Chem. com. 47*9 phosphoric acid, 34*5 alumina, 6*9 lithia, 6 soda, and 8*3 fluorine. Penig, Arendal, Montebras, also Hebron and Paris in Maine. Montehrasite, with no soda^ is perhaps distinct. Family Y. — Leucite. Tesseral; H. = 5...6 ; G. - 2-2...2-5. All fusible, ex- cept leucite, and all soluble and mostly gelatinise in hydro- chloric acid. They are silicates of alumina and of alkalies (or lime), often with chlorine, sulphur, or sulphuric acid. Their colours are white, gray, or often blue. Generally occur imbedded in volcanic rocks. ^^'^I T FTiriTE — I + 61. I.EUCITE. j ^^pQ3 ^ 3 _^ j^.Q ^ gjQ.-| Tesseral ; only 202 (Fig. 6). The crystals generally single. Cleavage, hexahedral very imperfect. Fracture Family.] SODALITE — HAUYNE — NOSEAN. 125 conchoidal. H. = 5-5... 6 ; G. = 2*4. ..2*5. Transparent to translucent on the edges ; vitreous, inclining to resinous. Colourless, but grayish, yellowish, or reddish-white or gray ; streak white. B.B. infusible ; with cobalt solution becomes blue. Soluble in h. acid, without gelatinising. Chem. com. 54*9 silica, 23*6 alumina^ and 21 "5 potash. Abundant in the lavas of Vesuvius, the tufas near Eome, and the peperino of Albano ; also at the Kaiserstuhl, and near Lake Laach. Eeadily distinguished from analcime by its infusibility and by never showing faces of the cube. 32. SODALITE.— 3 (Al Si + Na Si) + Na CI. Tesseral ; oo 0 (Fig. 3) ; massive and granular. Cleav- age, 00 0 more or less perfect. Fracture conchoidal or uneven. H. = 5*5 ; G. - 2i 3.. .2*29. Translucent ; vitreous, inclining to resinous. White, gray, and rarely green or blue. B.B. becomes white and fuses easily alone, sometimes intumescing to a clear glass ; with difficulty in borax. Gela- tinises with acids. Chem. com. 37 silica, 31*8 alumina, 19*2 soda, 4'7 sodium, and 7 '3 chlorine, but in the green sodalite from Vesuvius only 2 '5 5 chlorine. Greenland, Vesuvius, Ilmen Hills, Brevig and Fredriksvarn in Norway, and Litchfield in Maine. *33. Hauyne.— 2 (Al Si + Na Si) + Ca S. Tesseral ; chiefly oo 0, but more common in grains. Cleavage ocO moreor less perfect. H.=5...5"5 ; G.=2*4...2'5. Semi-transparent or translucent ; vitreous or resinous. Azure or skye-blue ; streak bluish-white. B.B. decrepi- tates violently, and melts to a bluish-green vesicular glass. Soluble and gelatinises in h. acid. Chem. com. 34*2 silica, 28'5 alumina, 11*5 soda, 4*3 potash, 10 '4 lime, and ll'l sulphuric acid. Vesuvius, Mount Vultur near Melfi, the Campagna of Eome, and Niedermendig near Andernach. 34. NosEAN.— 3 (Al Si -f- Na Si) + Na S. Tesseral, like hauyne, but oftener granular. H. = 5 '5 ; G. = 2*28. ..2*40. Translucent; vitreous to resinous. Ash or yellowish gray, sometimes blue, brown or black. B.B. becomes paler, and melts on the edges to a vesicular glass. 126 ITTNERITE — LAPIS-L AZULI — EUDIALITE. [Leucite Soluble in acids. Cliem. com. 36 silica, 31 alumina, 25 soda, and 8 sulphuric acid; but with 1 to 1*5 lime and 0-6 chlorine. Lake Laach and Eieden, near Andernach, on the Rhine. Zirkel says occurs in all phonolites in microscopic crystals. Skolopsite, granular, smoke-gray and reddish- white j G. = 2*53 ; is very similar. Kaiserstuhl. 35. Ittnerite.— Al Si + (Na, Ca) Si + 2 H. Tesseral, but only coarse granular. Cleavage, dode- cahedral distinct ; fracture imperfect conchoidal. H. = 5*5 j G. = 2-37. ..2*40. Translucent; resinous. Smoke, ash, or dark bluish-gray. In the closed tube yields much water. B.B. fuses, ^Y^th much effervescence and sulphur- eous smell, to a vesicular opaque glass. Soluble, and gelatinises in con. h. acid. Chem. com. by Whitney's analysis, 35-69 silica, 29*14 alumina, 5*64 lime, 12-57 soda, 1-20 potash, 4*62 sulphuric acid, 1*25 chlorine, 9-83 water and loss. Kaiserstuhl near Freiburg. Probably altered nosean. *36. Lapis-Lazuli, Lasurstein. Tesseral ; oc 0, but rarely distinct ; generally massive and fine granular. Imperfect dodecahedral cleavage. H. = 5-5 ; G. = 2-38. ..2-42. Translucent on the edges ; dull resinous or vitreous. Ultramarine or azure blue ; streak light blue. B.B. fuses readily to a white porous glass. In h. acid the powder is dissolved and gelatinises, evolving sul- phuretted hydrogen. Chem. com. by Yarrentrapp's ana- lysis, 45-50 silica, 5-89 sulphuric acid, 31*76 alumina, 9'09 soda, 3*52 lime, 0'86 iron, 0*42 chlorine, 0*95 sulphur, 0*12 water. Near Lake Baikal, China, Thibet, and Tartary, also in Monte Somma and Chili. It is used for ornamental purposes, and the preparation of ultramarine-blue. The colour both in it and the hauyne seems caused by some compound of sulphur, probably with soda. A mode of pre- paring the artificial colour was discovered by dir. Gmelin. 37. EuDiALiTE.— 6 il Si' + KZr. Hexagonal-rhoml)oliedral. li 73*^ 30'; also massive and granular. Cleavage, basal distinct. H. = 5...5*5; Family. 1 ANALCIME. 127 G. = 2*84. ..3*0. Semitranslucent or opaque; vitreous. Peach-blossom to brownish-red ; streak white. B.B. fuses easily to a light green opaque glass. Gelatinises in h. acid. Chem. com. about 50 silica, 16 '5 zirconia, and R=13 soda, 11 lime, 8 '5 protoxide of iron with manganese, and 1 -4 chlorine. Greenland ; Brevig ; and Magnet Cove in Arkansas. **Family VI. — Zeolite. Crystallisation chiefly rhombic and monoclinic ; also hexagonal, tetragonal, and tesseral. H. = 3-5...6, or mostly scratched by steel; G. = 2*0... 3*0. Mostly hyaline and white; rarely red, gray, or yellow coloured. Cleavage generally distinct. All yield water in closed tube ; all fusible B.B., mostly easily and often intumescing; all soluble in acids, and mostly gelatinise or deposit silica. They are hydrated silicates of alkalies, or alkaline earths, mostly with silicates of alumina, but rarely contain mag- nesia. Some mineralogists regard the water as basic, in union with silica, and Kenngott gives the formula in that form, thus — Analcime - [(Na'O . APO^) 2 SiO' -f 2 (ff 0 . SiO')l. Natrolite = [(Na'O . kVO') 2 SiO' -f 2 0 . SiO^. Stilbite - [CaO . KYO' + 6 (H^O . SiO')]. and the others similar. They are generally found in amygdaloidal cavities or fissures of trap or plutonic rocks, apparently as deposits from water percolating through them, and thus probably products of decomposing felspars. Never form constituents of rocks. Natrolite, Scolezite, Thomsonite, and the connected varieties, are marked by their needle-like radiating forms ; Stilbite and Heulandite by their broad foliated, pearly cleavage. AxTATnTT^rT. f + Na Si 2H, or 38. Analcime.-| ^Aroi3SiOVNa^O.Si6^+2ffO]. Tesseral ; crystals 202, seldomer cxOoo . 202 (Fig. 112), in druses; also granular. Cleavage hexahedral, very imperfect; fracture uneven. H. - 5-5 ; G. - 2*1. ..2-25. 128 XATEOLITE — SCOLEZITE. [Zeolite Fig. 112 Transparent to translucent on the edges ; vitreous. ^ATiite, grayish, greenish, yellowish, or reddish white ; also flesh- red, and very rarely leek-green. B.B. melts quietly to a clear vesicular glass. Completely soluble and gela- tinises in h. acid. Chem. com. 54'4 silica, 23*4 alumina, 14"1 soda, and 8*1 water, with occasionally a little potash or lime. Seisser Alp in Tyrol, and in Siebenburg ; Cyclopean Islands, Sicily ; the Yicentine, Xorway, Faroe, Iceland, Xova Scotia ; also Giant's Causeway ; and Glen- farg, Salisbury Crags, Dumbarton, Hebrides, and other parts of Scotland. Cuhoif, and the ClutJialite, are varieties. *39. Xatrolite. r ±1 Si' + Xa Si + 2 H, or Mesot}i)e. ' \ [Am . 2 SiO'^-^Xa'^O . SiO>2 ff 0]. Ehombic; ocP 91°, P polar edges 143° 20', and 142° 40', middle edge 53° 20'; crystals, cxP.P (Fig. 113), fine prismatic, acicular or fibrous, and radiating. Cleavage, ooP perfect. H. = 5...5-o; G. - 2-1 7. . .2-26. Pellucid: vitreous. Colourless or grayish-white, but some yellow, seldom red or brown. Is not pyroelectric. B.B. becomes obscure and melts Cjuietly to a clear glass colouring the flame yellow. Gelatinises in h. acid. Chem. com. 47 '2 silica, 27 alumina, 16*3 soda, and 9 '5 water, with a little lime and iron oxides. Clermont in Auvergne, Alpstein in Hessia, Hohent- Fig. 113. ^-g^ Swabia, Norway ; in Scotland, as in Mull, Canna, and near Tantallon Castle ; in Ireland at Glenarm and Portrush ; also in Xova Scotia, and other countries. Bergmannife, BadioJite, and Lehiuitife, are varie- ties ; also Galadite, H. - 4*5, with 4 Imie and lO'o water. Glenfarg, Kilpatrick, and Bishopstown. '''*40. ScoLEZiTE, Xeedlestone, Al Si'-t-Ca Si -f 3 H. Monoclinic ; C. = 89° 6^ ooP 91° 35', P 144° 20'; crystals, ooP . P . — P, prismatic or acicular. Twin crys- tals very common, united by a face of ocP'^oc, and one Family.'] THOMSONITE. 129 face with feathery striae (Fig. 114); also massive and radi- ating. Cleavage, ooP rather perfect. H. - 5...5'5 ; G. = 2 -2 ... 2 '3. Pellucid ; vitreous, fibrous varieties silky. SnoAV-white, grayish, yellowish, and reddish white. Distinctly pyro-electric. B.B. bends and twists in a vermicular manner, and melts easily to a porous glass. In h. acid gelatinises ; also soluble in oxalic acid, leaving oxalate of lime. Chem. com. 45-8 silica, 26*2 alumina, 14*3 lime, and 13*7 water. Very fine on StaflPa, also Mull and Skye ; at Berufiord in Iceland; in Faroe, in Tyrol, Auvergne, and India. The following are either varieties of, or closely allied to^ Scolezite or Natrolite : — Mesolite, with 4 to 6 soda and 10 to 14 water; Storr and Talisker, Skye ; Kinross ; Edinburgh ; Giant's Causeway, and Iceland, is perhaps a mixture of natrolite and scolezite. Earringtonite, compact, earthy, snow-white ; Portrush in Ireland. Antrimolite, white, fibrous, and opaque. G. = 2-096; H. = 3*75. Antrim. Foonahlite, rhombic prisms of 92° 20', otherwise like scolezite, from Poonah in Hin- dostan. Brevicite, radiated, massive, white, reddish-gray, or dark red ; Brevig. Mesole or Fawelite, radiating, fibrous ; transparent, pearly ; white, yellow, or gray. H. = 3*5. G. = 2'35. B.B. fuses with effervescence to a frothy enamel. Chem. com. 41 '3 silica, 28*4 alumina, 11*5 lime, 5*7 soda, and 13'2 water. Faroe, Schonen; Storr, Uig, and Portree in Skye. The last is perhaps a distinct species. ^*41. THOMSONITE, I 2 (M Si -f (Ca, I^a) Si) +5 H, or Comptonite. j [E AF Si' 0^ + 5 Si(i.]~-Bams. Ehombic ; ooP 90° 40', usually ooPoo ooPoo Poo or M, T, s (Fig. 115), terminating in an extremely — ^ obtuse dome xFoo (i) of 177° 23', like the basis with the plane broken. In druses, fan-shaped or radiated. Cleavage, macrodiagonal and brachy- diagonal equally perfect. H. =- 5...5-5 ; G. = 2*3 ...2-4. Translucent, but often obscure; vitreous, some- K M J 130 STILBITE — HEULANDITE. [Zeolite times pearly. White. B.B. intiimesces, becomes opaque, and fuses with difficulty to a white enamel. Soluble and gelatinises in h. acid. Chem. com. 37 '1 silica, 31*7 alu- mina, 17*3 lime but with 3 to 7 soda, and 13*9 water. Vesuvius, Sicily, Bohemia, Tyrol, Iceland, Faroe, Scotland (Lochwinnoch, Kilkpatrick Hills, St. Cyrus in Kincar- dineshire), and Nova Scotia. Chalilite and Scoulerite are varieties, Antrim. **42. Stilbite, ( M Sf + Ca Si' + 6 H, or Desmine. \ [AP 0' 3 Si 0' + Ca 0 . 3 Si 0^ + 6 0]. Ehombic ; P polar edges, 119° 16', and 114°; crystals, ooPoo (21) . ^Poo (T) . P (r) . OP (P) (Fig. 116), broad pyramidal, very often fascicular or diverging ; also radiat- ing or broad columnar, or maclecl. Cleav- age, brachydiagonal T very perfect. H. = 3-D..A; G. = 2'1...2'2. Translucent, or only on the edges ; vitreous ; pearly on T. AA'hite, red, gray, yellow, and brown. B.B. intumesces greatly, and melts to a white porous enamel. De- composed by c. h. acid, leaving slimy silica. Chem. com. 5 7 '5 silica, 16*4 alu- mina, 8*9 lime with 1 to 3 soda or po- tash, and 17*2 water. Andreasberg in the Harz, Kongsberg and Arendal, Ice- land, Faroe, and the Yendayah mountains in Hindostan ; Scotland, Talisker and Storr in Skye, Kilpatrick, Kilmalcolm, and Arran. Sj^hce- rost'ilhite and Hupost'ilhlfe are related species. jEdelforsite ; fibrous or columnar; H. = 6 ; G. = 2'6 ; is a stilbite ^\At\\ two atoms less water, or a laumonite mixed with quartz, ^delfors in Sweden. Fiix. 116. **43. HEULANDITE.— Al Si^-fCa Si' +5 H. Monoclinic ; C. = 63° 40', P^oo 50° 20'; crystals coFoo. a)Fco.P"(^ . OP. 2P {M,N,1\ T, -) (Fig. il7) ; mostly tabular, rarely prismatic; in druses or radiated lamellar. Cleavage, clinodiagonal very perfect ; brittle. Famihj,] BREWSTEKITE — EPISTILBITE. 131 H. = 3*5...4 ; Gr =2*1. ..2*2. Transparent to translucent on the edges ; vitreous or pearly. "White, but often flesh or brick red, and yellowish or hair brown. B.B. exfoliates, intumesces, and melts to a white enamel. Soluble in h. acid, leaving slimy silica. Chem. com. 59-1 silica, 16*9 alumina, 9*2 lime, and 14*8 water. Arendal, Kongs- berg, Andreasberg, Fassa Valley, Iceland, Faroe, Nova Scotia, New Jersey, and the Vendayah Mountains, Hindostan ; at Campsie, in Skye, and other parts of Scotland. Beaumontite is the same; Baltimore. Fig. 117. 44. Brewsterite. — Al Si^ + (| Sr + ^ Ba) Si' + 5 H. Monoclinic ; C. = 86''20'; crystals short prismatic, of several vertical prisms, bounded by an extremely obtuse clinodome (172°) (Fig. 118), are mostly small. Cleavage, clinodiagonal very perfect. H. = 5. ..5-5; G. = 2-12...2-2 (or 2-4). Pellucid; vitreous or pearly. White, gray, yellow, brown, or green. B.B. froths, intumesces, and fuses to a porous glass. Soluble in h. acid, and gela- tinises. Chem.. com. 54 '3 silica, 15*0 alumina, 10*1 strontia, 7-4 baryta with 1-3 lime, and 13*1 water; and thus with all the three alkaline earths. Strontian in Scotland, Giant's Causeway, Freiburg in the Bresgau, and the Pyrenees. 45. EPISTILBITE.— Al Si' + Ca Si'+ 5 H. Ehombic ; (xP (ilf) 135' 10', f^{t) 109° 46^ Poo {s) 147° 40'; in long prismatic crystals (Fig. 119). Macles united by a face of ooP ; also massive and granular. Cleavage, brachy diagonal very perfect. H. 3*5 ...4; G. = 2-3. ..2-4. Pellucid; vitreous or pearly. Colourless or white. B.B. melts with ^ ^ intumescence to a porous enamel. Soluble with- out gelatinising, but after ignition is insoluble. Chem. com. 59 silica, 17*5 alumina, 9 lime, with 1-5 soda, and 14*5 water, or like heulandite. Iceland and Faroe ; also in Skye and Nova Scotia. Fiff. 119. 132 APOPHYLLITE — PECTOLITE. [Zeolite 46 APOPHYLLITE + 2 H) + KF, or 4b. APOPHYLLITE.- , g. ^^^j^^^^ Tetragonal; P about 120° 30', but 1° less or more; crystals P. ooPoo (P, m) (Fig. 120) and OP, are pyramidal, or short prismatic, or tabular ; usually in druses or lamellar. Cleavage, basal perfect; ooPoo imperfect; brittle. H. = 4'5...5; G. = 2'3... 2-4. Pellucid ; vitreous ; on OP pearly {ichtJuh ojMIialm). Colourless, but yellowish, gray- ish, or reddish white, to rose or flesh red. B.B. exfoliates, intumesces, and melts easily to a white enamel. Powder readily soluble in h. acid, leaving slimy silica. Chem. com. 53 silica, 24*7 lime, 15*9 water, 2*1 fluorine, and 4*3 potassium. Occurs at Utoe, Aussig, the Tyrol, Anclreasberg, Siberia, Greenland, Iceland, Faroe. At Eaith in Fife, Eatho, in Skye at Talisker, Dunvegan, and Quiraing; and Port- rush in Ireland. Gi/rolite, spherical radiated concretions, with 50*7 silica, 1*48 alumina, 33*24 lime, 0'18 magnesia, and 14*1 8 water ; Storr in Skye, seems a variety. Also XylocJior from Iceland. 47. Okexite. — Ca Si' + 2 H. PJiombic; ocP 122° 19'; usually fine columnar or fibrous. H. - 5 ; G. - 2 '28... 2 '3 6. Pellucid ; slightly pearly. Yellowish to bluish-white. B.B. froths up and melts to an enamel. In powder easily soluble in h. acid, leaving gelatinous flakes; after ignition insoluble. Chem. com. 56-6 silica, 26*4 lime, and 17 water; or apophyllite without the fluoride. On Disco Island, Faroe, and Iceland. 48. Pectolite. — 4 Ca Si -f Na Sr + H. Monoclinic, but mostly spheroidal, radiating, and columnar. H = 5 ; G. = 2-74... 2 '9. Translucent on the edges ; slightly pearly. Grayish-white or yellowish. B.B. melts easily to a v/liite enamel-like glass. Soluble in h. acid, leaving flaky silica ; after ignition gelatinises per- fectly. Chem. com. 54*2 silica, 337 lime, 9*4 soda, and Family.] LEVYNE — GMELINITE. 133 2-7 water. Monte Baldo, Monte Monzoni in Tyrol. In Scotland at Talisker in Skye, near Ballantrae, white, fibrous, and nearly three feet long ; Kilsyth {Stellite), Katho, Cor- storphine, and Castle Eock, Edinburgh. Eesembles wolla- stonite in form and composition, the soda replacing the lime and the water from decomposition. 49. Levyne.— ^1 Si' + Ca (K, Na) Si-f 4 H. Hexagonal-rhombohedral ; E 79° 29'; crystals, OE. E -|E, thick tabular, in perfect intersecting macles (Fig. 121). H. = 4 ; G. = 2-1 ...2-2. Chem. com. 44*5 silica, 23*8 alumina, 10-7 lime, 1-6 potash, 1-4 soda, and 17*4 water. Otherwise like chabasite. Faroe, Glenarm, Storr in Skye, and Hartfield Moss in Eenfrewshire. 50. Chabasite, Lime-CL— A1 Si%Ca (Na,K) Si+6 H. Hexagonal-rhombohedral; E94°46'; E mostly alone but also with -^E and -2E (Fig. 122). Intersecting macles very common ; crystals in drases and striated. Cleavage, E rather perfect. H. = 4 . . . 4 '5 ; G. = 2 . . . 2 '2. ^ Transparent to translucent; vitreous. Colourless, grayish, yellowish, reddish to flesh-red. B.B. fuses to a finely porous enamel. Soluble in h. acid, leaving slimy silica. Chem. com. 47*3 silica, 20*3 alumina, 11*1 lime (with 0 to 2*5 soda and 0-2 to 3 potash) and 21-3 water. Faroe, Ice- land, Greenland, Aussig in Bohemia, Giants' Causeway, Kilmalcolm in Eenfrewshire, in Skye, and other places in Scotland. GloUalite of Thomson, from near Port-Glasgow, seems chabasite. Fhacolite, with rather less silica and more alumina, is a variety ; Leipa in Bohemia. 51. Gmelinite, Soda") ^^-.3 . /a, ttn q- , « tt Chabasite! j + K) Si + 6 H. Hexagonal; P 80° 13'; crystals P . OP . ocP (Fig. 123). The faces of P striated parallel to their polar edge; those of the prism horizontally. Cleavage, coP distinct. Gela- 134 FAUJASITE — HAEMOTONE. \_Zeolite tinises with li. acid ; otherwise like chabasite. Chem. com. 47*6 silica, 19"7 alumina, 12 soda (with 3 to 5 lime, and 0*4 to 2 jDotash) and 20*7 water. Talisker in Skye, Glenarm in Antrim, A^icenza. Lederite, with only 9 per cent water, seems a variety ; Cape Blomidon, Nova Scotia. 52. FAUJASITE.— 2 ±1 4 (Ca, 'Naf Si' + 18 H. Tesseral ; octahedrons. Fracture uneven ; brittle. H. = 7. Gr. = 1'923. Transparent; vitreous or adaman- tine. AMiite or brown. B.B. intumesces and fuses to a white enamel. Soluble in h. acid. Chem. com. 46 silica, 17 alumina, 5 lime, 5 soda, and 27 water. Kaiserstuhl. 53. Edixgtonite. — 4^:1 Si' + 3 Ba Si+ 12 H. Tetragonal, hemihedral ; P. 87° 9' ; formed as a sphe- noid (P), with polar edges 92° 51'; also (n), polar edges 129° 8', and ocP (m) (Fig. 124). Cleavage, ocP, perfect. H. = 4. ..4-5 ; G-. = 2-7.r.2'75. Translucent ; ■\dtreous. Grayish-white. B.B. fuses diffi- cultly to a colourless glass. Chem. com. 37*3 silica, 23*7 alumina, 26*5 baryta, and 12 '5 water (ctnalysis). Kil- patrick Hills, Dumbartonshire. ^*54. Harmotome, J ^1 Si' + Ba Si' + 5 H, or Cross-stone. \ [BaO . Al' 0'^ + 5 (ff 0 . Si 0^)]. PJiombic ; P polar edges 119° 4' and 121° 6' (or 120° 1' and 120° 42^, and ooP 88° 14^; crystals, ocPco (^^). ooPoo (o).P. Poo , short prismatic. Generally in perfectly intersecting macles (Fig. 125). (Xow thought monoclinic and the macles of four crystals.) Cleavage, ma- crodiagonal and brachy diagonal imperfect ; brittle ; fracture uneven. H. = 4'5 ; G. = 2*3. ..2'5. Translucent; vitreous. Col- ourless, but white, gray, yellow, brown, or red. B.B. fuses rather difficultly but quietly to a clear glass. Soluble, but not readily, in h. acid, with deposition of silica. Chem. com. Family.] PHILLIPSITE — GISMONDINE. 135 46-5 silica, 15-9 alumina, 23'7 baryta (with 1 to 3 lime and 1 to 2-5 potash), and 13-9 water. Andreasberg,^ Kongs- berg, Oberstein. Strontian (Morvenite) ; Old Kilpatrick, Campsie Hills, and Corstorphine, Scotland. 55. PHILLIPSITE.— Al Si^ + (Ca, K) Si + 5 H. Ehombic; P polar edges 119° 18' and 120° 42'. Forms, macles, and other characters, like harmotone. G. = 2*15. ..2*20. B.B. fuses easily with slight intumescence; gelatinises in h. acid. Chem. com. 48-6 silica, 20*2 alumina, 7-3 lime, 6-2 potash, and 17*7 water. Giessen, Marburg, Cassel, Iceland, and the Giants' Causeway. 56. Herschelitk— Al Si' + (Na, K, Ca) Si + 3 H. Hexagonal (or rhombic?); P polar edges, 124° 45'; crys- tals ooP . OP . H. = 4-5 ; G. - 2-06. Translucent ; pearly ; white. B.B. fuses readily to a white enamel. Chem. com. 48-5 silica, 20*1 alumina, 9*2 soda, 4*6 potash (with 0-2 to 5 lime), and 17-6 water. Aci Eeale and Palagonia in Sicily. Eichmond, near Melbourne, Australia, but with 46 silica, 22 alumina, 7'1 lime, 5*5 soda, 07 potash, and 19 water. 57. Zeagonite.— Al Si' + (Ca, K) Si + 4 H. Ehombic ; P polar edges 120° 37' and 122° 44' ; crys- tals single or in groups. H. = 5, on angles and edges = 7 or more ; G. = 2-213. Transparent ; vitreous. Colour- less, white, or bluish. B.B. becomes white, falls down, shines, and melts to a clear glass. Capo di Bove. 58. Gismondine, Abrazite. — Al Si + Ca (K) Si -i- 4 H. Tetragonal (or rhombic?); P 92° 30'; crystals, P or with ooPoo , in groups. Cleavage, P. imperfect. H. = 5, on edges and angles = 6 ; G. = 2-265. Semitransparent to translucent; vitreous. Grayish-white to pale-red. B.B. intumesces, becomes opaque, and melts to a white enamel. Chem. com. 35 silica, 29 alumina, 15*7 lime (with 2*8 potash), and 20*3 water. Vesuvius, Aci Castello, and Capo di Bove. 136 LAUMONITE — LEONHARDITE. [3Iica 59. Lauinionitk— Si^+ Ca Si + 4 H. Monoclinic ; C. = 80° 42', oo P 86° 15', oo P : ~ P^oo (or if : P) 113° 30' j crystals (Fig. 126) prismatic, also colum- nar. Cleavage, prismatic perfect ; clinodiagonal in traces ; rather brittle. H. = 3 . . . 3 '5 j G. = 2 '2 ... 2 -3. Pellucid ; vitreous ; on cleavage pearly. White, grayish, yel- \ZA lowish, and reddish. In the air soon decomposed. B.B. intumesces and melts easily to a white enamel, which becomes clear in a stronger heat. Soluble Mg. 126. gelatinises in h. acid. Chem. com. 50*9 silica, '21-9 alumina, 11*9 lime, and 15*3 water. Huel- goet, in Brittany, Eule near Prague, Fahlun, Iceland, Faroe, Snizort and Storr in Skye, Dumbarton, and other parts of Scotland, and in North America. 60. Leoxhardite.— i^l Si^ + Ca Si + 3 H. ^ Monoclinic ; ooP 83° 30', oo P : -P^oo 114° ; crystals, prismatic, and grouped in bundles ; also granular or co- lumnar. Cleavage, ocP very perfect, basal imperfect. Very friable. H. = 3...3-5j G. = 2'25. Translucent on the edges ; pearly ; yellowish-white, B.B. exfoliates, froths, and melts easily to a wliite enamel. Becomes opaque, and decomposes quickly in the air. Chem. com. 53-7 silica, 22*4 alumina, 12*2 lime, and 11*7 water. Schemnitz. Ca]oord- anite, reddish-gray, fibrous and radiating, from Caporciano, Tuscany, is identical. **Family YIL— Mica. Crystallisation monoclinic or rhombic, and hexagonal or rhombohedral. Cleavage mostly very perfect in^ one direction (basal), and thin laminae flexible. Pellucid, with a strong, often pearly or semimetallic lustre. H. = 2...3, more ^ rarely 1 ... 6 ; G. = 2 '5 ... 3. B.B. mostly fusible! Are silicates of alumina, with silicates of potash, magnesia, lithia, and protoxides of iron and manganese, with or with- out water. Lime is rare, or almost wanting. They are mostly constituents of the plutonic or volcanic rocks.* * Neither tlie oj^tical nor crystallographical characters of the micas, Nos. 67 to 71, are ^vell determined. AH magnesia micas were formerly regarded as mouoaxial and hexagonal, but some now appear to be binaxial, Family.] MUSCOVITE — LEPIDOLITE. 137 ** 61. Muscovite, ) ^. ^ ^-.g Potash-Mica, Phen- y^ 5^':^3^^ + i^^^ gite, Binaxial-Mica. j [^1 0 . SiO +E0. SiO^].-Bams. Ehombic. Crystals chiefly rhombic or six-sided tables, with ooP 120° and 60° nearly. Imbedded, or in druses j also scaly, foliated, or lamellar. Macles rather rare. Cleav- age, basal highly perfect ; sectile, and in thin laminae elastic. H. = 2...3; G. = 2-8...3-1. Pellucid in various degrees j optically binaxial ; metallic-pearly, on some faces vitreous. Colourless, but white, gray, green, red, brown, black, and rarely yellow. In closed tube usually yields water, with traces of fluorine. B.B. loses its transparency, and fuses to an obscure glass or white enamel. Not affected by h. or s. acids. Chem. com. very variable, but by second formula [EO = i K^CfffO] 45-1 silica, 38-6 alu- mina, 11*8 potash, and 4'5 water. The analyses give also peroxides of iron (or protoxide) and manganese, with traces of lime, magnesia, and soda, and most also 1 per cent or under of fluorine. The green micas (Fuchsite) also 4 to 6 chrome oxide. Abundant as a constituent of granite, gneiss, mica-slate, and other rocks. Large plates in Nor- way, Sweden, and especially in Siberia, often a yard in diameter, and used for windows, but become white on exposure. Fine crystals, Vesuvius, St. Gotthardt, Pargas, Arendal, Utoe, Fahlun, Kimito, Cornwall, and Aberdeenshire. Damoiirite. — H. = 1*5 ; soluble in sulph. acid, leaving silica, from Pontivy in Brittany ; Margarodite from Con- necticut and Ireland ; DidrimUe from Zillerthal, are only mica, as water appears to occur in all varieties as an essential constituent. Paragonite or mica-slate, from St. Gotthardt, is similar, but contains 8 '5 soda, and B.B. in- fusible. *62. Lepidolite, Lithia-Mica. Monoclinic or rhombic ; physical characters like potash- mica, but colour often rose or peach-blossom red. In with the angle between the axes small ; in biotite under 5°, often 0° to 1° or 2° ; in phlogopite, 5° to 20°, The crystallisation of the potash mica and lepidolite is most probably rhombic. The chem, com. also is not well represented by any general formula. BIOTITE. [J//,^ the closed tube shows evident fluorine reaction. B.B. melts very easih/ with efl'ervescence to a colourless, brown, or rarely black magnetic glass, colouring the flame red. Imperfectly soluble in acids, wholly so after fusion. Chem. com. very uncertain. Analyses give 40 to 52 silica, 20 to 34 alumina, 0 to 27 iron peroxide, 0 to 5 manganese peroxide, 5 to 10 potash, 2 to 6 lithia, 4 to 8 fluorine, and 0 to 2 soda. Part of the iron is pro- bably the protoxide and most show also water. Eammels- berg regards the fluorine as replacing part of the oxygen, both in the bases and acids. Penig and Zinnwald, Saxony, Ptozena, Moravia (contains rubidium), Paris and Hebron in Maine ; St. Michael's Mount, Cornwall ; Loch Fine, Ballachulish (in limestone), Portsoy (in serpentine), Scotland. Sometimes used as an ornamental stone and for preparing lithia. *^63. BiOTiTE, Magnesia- 1 ±1 Si -f (Mg, K, Fe)'^ Si, or Mica. Si' + m-R' Si. Hexagonal, rhombohedral ; E 62° 56' ; crystals mostly tabular, rarely short prisms. Cleavage, basal very perfect ; sectile ; in thin plates elastic. H. = 2'5...3 ; G. = 2'85... 2-9. Transparent, but often only in very thin plates (and generally monoxial) ; metallic, pearly. Usually dark-green, brown, or black ; streak greenish-gray or white. B.B. diflicultly fusible to a gray or black glass. Completely soluble in con. s. acid, leaving white pearly plates of silica. Chem. com. very variable. In the second formula (Bams.) B is alumina and iron per- oxide, 11 magnesia, iron protoxide, potash and water, whilst ra = 2, 3, 4 or 6. Most characteristic is the large amount of magnesia and iron. Analyses give 37 to 44 silica, 13 to 22 alumina, 2 to 27 iron peroxide, 10 to 30 magnesia, 0 to 10 potash, 0 to 2 fluorine, and 1 to 3 water. Pargas, Bodenmais, Monroe in Xew York, Greenland, near Aberdeen, and in other parts of Scotland. Ihihellan, brownish-red, Bohemia and Saxony, is a decomposed variety, ritlorjcqnfe, yellow or copper red from limestone. New York and Canada, also a magnesian mica, but the crystals rhombic and binaxial. Family.'] LEPIDOMELANE — CHLOHITE. 139 64. LEPIDOMELANE. — (±\ Pe) Si + (Fe, K) Si. Hexagonal, small six-sided tables. Cleavage, basal perfect ; rather brittle. H. = 3 ; G. = S'O. Highly vitre- ous ; opaque and raven-black ; or translucent and leek- green ; streak mountain-green. B.B. becomes brown, and fuses to a black magnetic bead. Soluble easily in h. acid, leaving pearly scales of silica. Chem. com. 35 to 37 silica, 12 to 17 alumina, 24 to 27 iron peroxide, 1 to 12 iron protoxide, 4 to 9 potash, 3 to 5 magnesia, 0*5 to 1 lime, 1 to 2 manganese protoxide, with 4 to 7 water. Thus a magnesian mica with much iron — common in the granite of Ireland and Persberg, Sweden. 65. Chlopjtoid. — Fe Si + ^1 H. Granular, foliated. Cleavage, in one direction perfect ; brittle. H. =-5-5...6; G.= 3-55. Opaque ; weak pearly. Blackish-green ; streak greenish- white. B.B. infusible, but becomes darker and magnetic. Not affected by acids. Chem. com. 23*8 silica, 40*6 alumina, and 28*5 iron protoxide, and 7-1 water, but generally 3 to 4 per cent magnesia. Kosoibrod in the Ural, Tyrol, and in Canada (chloritoid slate.) Sismondine, St. Marcel in Piedmont, is similar ; and Masonite, from Ehode Island. 66. Ottrelite.— AP Si' + 3 (Fe, Mn) Si + 3 H. Monoclinic {f} in thin hexagonal tables. Cleavage, parallel to the lateral faces, rather perfect. Scratches glass. G. = 4-4. Translucent ; vitreous. Greenish or blackish gray. B.B. melts difficultly on the edges to a black magnetic globule. Powder soluble in warm s. acid, Chem. com. 43-9 silica, 24*3 alumina, 17*0 iron protoxide, 8*5 man- ganese protoxide, and 6*3 water. In gray clay-slate at Ottrez in Belgium ; Pyrenees. Chlorite. — The minerals (6 7 to 70) formerly thus named are now divided into several species, but there is much con- fusion in the names, increased by their close agreement in chemical and physical characters. Kenngott gives for the whole, including also kammererite, [RO . 2H'0-f 2(R0 . Si 0")], or RH + 2R Si,— R being chiefly magnesia replaced in part 140 CHLOKITE— CLINOCHLORE. [Mica by iron protoxide, and the silicate Mg Si also replaced in part by alumina = Al 0 . Al 0^. All have cleavage basal highly perfect ; laminae flexible, but not elastic ; thin plates trans- parent or translucent ; pearly on the basis. Green, but red by light transmitted transverse to the chief axis. In closed tube yield water. **67. Chlorite 1 2 E Si + ^1 -i- 3 H, or (Eipidolite, G. Rose), j [2 (2 EO. Si 0') +AP 0^ 3ff 0]. Hexagonal ; P 106° 50' ; crystals tabular of OP . ooP, or OP. P (Fig. 127), often in comb-like or other groups ; ^ ^ generally foliated and scaly. H. = 1...1-5. G. ■• ) ^ = 2*78. ..2'96. Leek to blackish green ; streak Fig. 127. greenish-gray. B.B. exfoliates ; difficultly fusible on thin edges to a black glass; soluble in con. sul. acid. Chem. com. when 4 E, = 3 Mg + Fe, =:26-3 sil., 21 '8 al., 25-5 mag., 15-0 Fe, and 11-5 water. = 2Mg+2re,=24-6 ... 201 ... 15'9 ... 28-5 ... 10-9 ... but the analyses variable. Common in the Alps, Scan- dinavia, the Ural, the Harz, Cornwall, Cumberland, Wales ; Portsoy, Glen Tilt, Jura, and other parts of Scotland. 68. Pennine.— 4 Mg Si + Mg' Al + 5H. Hexagonal, rhombohedral; E 65^28' (64° 30'Kenngott). Crystals chiefly very acute rhombohedrons, with or without the basis, and in groups or druses. Lustre somewhat resinous. H. = 2... 3; G. = 2-6. ..2-77. Streak, greenish- white. B.B. exfoliates, becomes white, and fuses on the edges to a white enamel. Completely soluble in warm s. acid. Chem. com. 33'6 silica, 14*4 alumina, 39*4 magnesia, and 12- 6 water; but with 5 to 6 iron protoxide replacing magnesia. Zermatt in Valais, Schwarzen stein in Tyrol, Ala in Piedmont, and Mauleon in the Pyrenees. Leuchten- hergite, yellowish-white, from Slatoust, is the same. 69. Clinociilore, Eipidolite ) ^ Vr a ;-, (Chlorite, G. Jiose:). | 3 Mg Si+Mg' Al-f-4 H. Monoclinic ; C. = 76° 4'; ooP 121° 28', OP :P 113° 59', OP : cx)P 192° 8'. Crystals - 2P . P . 4P^ oo . OP (n, m, Fj Fig. 128). Macles common ; also in groups Family.'] KAMMERERITE. 141 and druses. Lustre somewhat vitreous or resinous. H. = 2. ..3 ; G. = 2-6. ..2-8. B.B. becomes white, and fuses on thin edges to a grayish-yellow enamel. Chem. com. 30 '3 silica, 17*3 alu- mina, 40*3 magnesia, and 12'1 water, but in most 3 to 4 iron protoxide, and some perox- ide of iron and chrome. Traversalla in Pied- mont, West Chester in Pennsylvania, Achma- towsk in Ural, and Leugast in Bavaria (massive). Ejpichlorite, Metachlorite, Helminth, Belessite, and Grengesite, are other chlorite-like minerals. 70. Kammererite. — 3 Mg Si -h Al Si + 5 H. Hexagonal ; P 140° 16^ and P : OP = 105° 52', crystals OP . 00 P tabular and prismatic ; but usually massive and foliated. Cleavage, basal perfect. Sectile, flexible. H. = 1*5. ..2; G. = 2*6. ..276. Translucent; pearly. Violet- blue, reddish, or greenish. Feels greasy. B.B. exfoliates without fusing. Chem. com. 37'0 silica, 14*2 alumina, 1*0 chrome oxide, 31*5 magnesia, 1'6 lime, 1*5 iron protoxide, and 13'0 water in that from Bissersk. Varieties from Lake Atkul, Siberia, and Texas in Pennsylvania, give 5 chrome oxide, and agree with chlorite. Rhodochrome. — Massive, fine scaly, splintery fracture. H. = 2-5...3 ; G. = 2*668. Greenish-black, in fine splinters peach-blossom red. Tino in Greece, the Ural, Styria, and near Baltimore. Tabergite from Taberg ; Fermiculite, in fine scales, twisting up B.B., from Millbury, Mass. ; smd Loganite, from Canada, are closely allied. Fyrosderite, massive (but rhombic 1). Cleavage, in two directions at right angles, the one perfect, the other im- perfect ; fracture uneven, splintery. Sectile. H. = 3 ; G. = 2 '7... 2 -8. Translucent; dull, or weak |)early. Apple, emerald, or grayish green. B.B. fuses with difficulty to a gray glass. With borax forms a chrome-green glass. Chem. com. like kammererite, and probably identical. Elba. ChanikrUe found with it is similar, but with 12 lime. 142 TALC — PYROSMALITE — CRONSTEDTITE. [Mica **71. Talc— Mg' SiVH,or [3 (MgO.SiO^)+ffO.SiO']. Ehombic, or monoclinic. Earely found in six-sided or rhombic tables. Generally massive, granular, or scaly. Cleavage, basal very perfect. Soft, sectile, and flexible, in thin plates. H. = 1 ; G.- 2*6. ..2'8. Transparent in thin plates, and optically binaxial ; pearly or resinous. Colour- less, but generally greenish or yellowish-white, to apple, leek, or olive green. Feels very greasy. B.B. emits a bright light, exfoliates, and hardens (H.==6), but is infusible ; with cobalt solution becomes red. Not soluble in h. or s. acid before or after ignition. Chem. com. 63 '5 silica, 31*7 magnesia, and 4*8 water; but analyses give 57 to 63 silica, 0 to 4*7 alumina, 30 to 35 magnesia, 0 to 2*3 iron protoxide, with traces of lime and nickel oxide, and 2 to 6 water. Greiner in Tyrol, Sala, Fahlun, the Pyrenees, Unst in Zetland, Cairnie in Aberdeenshire, and many parts of the Scottish Highlands (talc-slate). Used as crayons ; also for forming crucibles and porcelain. Steatite. — Massive. Gray, red, yellow, or green. B.B. melts in fine splinters to a white enamel ; but in other respects acts like talc, of which it seems only a compact variety. Brian9on, Wunsiedel, the Lizard Point, Cornwall, Portsoy, and near Kirkcaldy, Scotland. Savage nations cut the steatite into culinary utensils. Potstone is a mix- ture of talc, chlorite, and other minerals. 72. PYROSMALITE.— (Fe, Mn)' Si' -f 2 H. Hexagonal; P 101° 34'; crystals ocP . OP, tabular; also granular. Cleavage, basal perfect, ooP imperfect ; brittle. H. = 4...4-5; G. = 3-0. ..3-2. Translucent to opaque ; resinous, or metallic pearly. Liver-brown to olive-green. B.B. fuses to a black magnetic globule. Wholly soluble in c. n. acid. Chem. com. 35*5 silica, 27*5 iron protoxide, 21*5 manganese protoxide, 8 chloride of iron or manganese, replacing protoxide, and 7*5 water. Rare. Nordmark in SAveden. • 73. Cronstedtite, ") ••• •;. Vr ••• Cl.loro„.elan. «^ + (^'^^^ Mg/ Si + 3 H. Itliombohcdral, chiefly radiated, columnar. Cleavage, Family^ STILPNOMELAN — MAEGAKITE. 143 basal perfect; thin laminae elastic. H. = 2*5 ; Gr. = 3*3 ...3*5. Opaque or translucent; highly vitreous. Eaven- black; streak dark-green. B.B. intumesces, and melts on the edges slowly to a steel-gray globule. Gelatinises with h. or s. acid. Chem. com. 22 silica, 29 iron peroxide, 39 iron protoxide (with 1 manganese protoxide and 4 mag- nesia), and 10 water. Przibram ; Huel Maudlin, Corn- wall ; and Conghonas do Campo in Brazil (Sideroschisolite). 74. Stilpnomelan.— (Fe Mg)' (Si, ^1)' 2 H. Massive or radiating-foliated. Cleavage, one very per- fect ; rather brittle. H. = 3 . . . 4 ; G. = 3 ... 3 '4. Opaque ; vitreous, inclining to pearly. Greenish-black ; streak green- ish. B.B. fuses with difficulty to a black shining globule. Imperfectly decomposed by acids. Chem. com. 45 '3 silica, 6'9 alumina, 38*3 iron protoxide (with 2 to 3 magnesia), and 9*5 water. Zuckmantel, Silesia, and Wielburg, Nassau. 5 ESi-f 6 KAl. 75. Clintonite, Seybertite, Holmesite, Chrysophane. Hexagonal or rhombic in six-sided tables, or massive and foliated. Cleavage, very perfect in one direction, traces in another. H. = 4*5. ..5-5 ; G. = 3 to 3-16. Translucent ; pearly on the cleavage. Wax-yellow or reddish-brown. Soluble in con. h. acid. B.B. infusible alone, but some become white and colour the flame yellow. Chem. com. 20 silica, 39 alumina, 3*5 iron peroxide, 21 magnesia, and 13 '5 lime; but also some soda, potash, and (2 or less) zir- conia. Amity, New York. Disterrite, Brandisite, from Monzoni, in Tyrol ; H. =^ 5 on basis, 6... 6 '5 on the prism ; when fresh blackish-green, but reddish-brown after exposure ; Xanthophyllite from Slatoust ; and Groioioite, coarse foliated; H. = 2'5 ; G = 2*73 ; rose or brown red ; Gropptorp in Sweden ; are closely allied . 76. Margarite, Pearl-) - • - . - ■ mica, Emerylite. | -f (Ca, Na, Mg) Si + H. Ehombic ; rarely in six-sided tables ; generally granular foliated. Cleavage, one very perfect. Thin plates slightly elastic. H. = 3*5. ..4'5 ; G. = 3*0. Translucent; pearly. 144 PYROPHYLLITE — PHOLERITE. [Mica Snow-white, reddish-white, or pearl-gray. B.B. intumesces and difficultly fusible. Soluble in acids. Chem. com. 30*1 silica, 51 '2 alumina, 11*6 lime, 2-6 soda, 0*5 to 3 magnesia, and 4 '5 water. Sterzing in Tyrol ; Asia Minor and Greece, with emery; and in Pennsylvania. Diphanite, in hexa- gonal prisms, bluish-white ; B.E. fuses to an enamel ; from the Ural ; is nearly allied. Euphyllite. — Like mica, but less readily cleavable. H. = 4 ; G. = 3. Pellucid ; bright pearly ; colourless. B.B. exfoliates with a bright light, and fuses on the edges. Contains 40 silica, 42 alumina, 1*4 iron peroxide, 1*4 lime, 3*3 potash, 5 soda, and 5*5 water. Unionville, Penn- sylvania. 77. Pyrophyllite. — Al Si* -f H. Ehombic C?), but radiated, columnar, or foliated. Cleav- age very perfect ; flexible ; sectile. H. = 1 j G. = 2-8... 2 '9. Translucent ; pearly. Light verdigris-green to yellowish- white. B.B. swells up with many twistings to a white infusible mass. Partially soluble in sulphuric acid. Chem. com. 67 silica, 28 alumina, and 5 water, with 0*1 to 4 magnesia and lime. Ural, Spaa, Morbihan, Westana in Sweden, Carolina, and Brazil. 78. Anauxite.— Al Si' -f 3 H. Granular, with a very perfect cleavage in one direction. H. = 2...3; G. = 2-2,..2-4. Translucent on the edges; pearly. Greenish-white. B.B. becomes white and fuses on thin edges. Chem. com. 60*5 silica, 26 alumina, and 13*5 water. Bilin in Bohemia. 79. Pholerite, Nacrite. — Al Si' + 2 H. In minute six-sided tables, in fan-like groups ; usually fine scaly. H. = 0'5...1 ; G. = 2*35... 2*6. Glimmering or pearly. Snow or yellowish wliite. B.B. infusible, with cobalt solution blue. Chem. com. 4 6 '3 silica, 39*8 alumina, and 13 '9 water, but often impure. Thus a crystalline form of kaolin. Common in mineral veins and clay-ironstone of the coal formation, as at Fins in the Allier dept., Mons, Freiberg, and Pennsylvania. Family.] EOSELLAN — SERPENTINE. 145 80. EOSELLAN Poly- 1 g.3 ^ 0^ (3 ^ ^ Si + 2 H. argite, Eosite. J ^ Small grains, with perfect cleavage. H. = 2'5 ; G. = 2*72. Translucent; splendent; fine rose-red. B.B. fuses with difficulty to a white slag. Chem. com. 45 silica, 35 alumina, 6*6 potash, 3-6 lime, 2*45 magnesia, and 6*5 water. Aker and Tunaberg in Sweden. **Family VIII. — Serpentine. Massive or rhombic. H. = 1...4, rarely more ; G. = 2-3... 3*0. Often compact or fibrous; most feel greasy. Colour often green or yellow, with resinous lustre. B.B. not or difficultly fusible. Mostly soluble in acids. Chem. com. generally hydrated silicates of magnesia, partly re- placed by protoxide of iron. Occur in plutonic or altered rocks ; the serpentine often in large masses or beds. --81 SERPENTINE I '^^^+^ ^ = ! ^H^^ 81. TERPENTINE. | j-^ ^ ^ SiO^ -f 2 ff 0]. Crystallisation uncertain ; generally massive, and granu- lar or fibrous. Fracture flat-conchoidal, uneven, or splintery. Sectile and slightly brittle. H. = 3... 3*5 ; G. = 2*5. ..2-7. Translucent to opaque ; dull resinous. Green, gray, yellow, red, or brown, often in spots, stripes, or veins ; streak white, shining. Feels greasy, but does not adhere to the tongue. In the closed tube yields water and becomes black. B.B. becomes white, and fuses with much difficulty on thin edges. Soluble in h. or easier in s. acid. Chem. com. 43*5 silica, 43*5 magnesia, and 13 water, but with 1 to 8 iron protoxide, and also carbonic acid, bitumen, and chrome oxide. Varieties are — 1^^, Noble Serpentine, brighter coloured and more translucent; 2d, Picrolite or fibrous (H. = 3*5... 4*5) ; 3d, Common or compact ; 4:th, Chrysotile {Baltimorite, Metaxite), in fine asbestiform fibres, easily separated, with a metallic or silky lustre. G. = 2'219. Common in Nor- way, Sweden, North America, the Lizard Point in Cornwall, in Shetland, Portsoy, Ballantrae, and many parts of Scot- L 146 AXTIGORITE — PICROSMIXE. [Seiyentine land. The chrysotile, at Eeiclienstein in Silesia, the Vosges Mountains, and North America. Serpentine is often a pro- duct of decomposition or pseudomorph of various minerals, as augite, hornblende, olivine, spinel, garnet, etc. It forms whole rocks and mountains, is manufactured into various ornamental articles, and used for preparing magnesia. Marmoliie, Avith cleavage in two directions, and pro- bably monoclinic, from the serpentine of Hoboken, in Xew Jersey, and other parts of North America, also in Finnland, agrees nearly in characters and chem. com. 3 Mg Si + 2 Mg ff, "vrith serpentine. 82. Antigorite. Very thin, straight laminae. H. = 2*5; Gr. = 2-62. Transparent or translucent. Green, with brown spots; streak white. B.B. very thin edges fuse to a yellowish- brown enamel. Chem. com. 41 silica, 3 alumina, 6 iron protoxide, 37 magnesia, and 13 water. Antigorio in Pied- mont, probably serpentine. 83. Hydrophite.— (Mg, Fe)' Si' 4- 4 H. Massive or fibrous. Fracture uneven. H. = 3...4; G. = 2 '65. Mountain-green ; streak lighter. B.B. infusible. Chem. com. 39*5 silica, 24-6 iron protoxide, 20-5 magnesia, and 15-4 water, but with some alumina and (2 to 4^ man- ganese ^Drotoxide. Taberg in Sweden, and New York. 84. PiCROSMiXE. — 2 Mg Si -i- H. Ehombic, but massive. Cleavage, ccPo) perfect; less so in other directions. Very sectile. H. = 2-0...3 ; G. = 2-5.. .2-7. Translucent or opaque; vitreous, but pearly on aPco . Greenish-white, gray, or blackish-green ; streak colourless. Yields a bitter odour when breathed on (hence the name). In closed tube gives water and blackens. B.B. becomes white and hard ( = 5). Chem. com. 55*8 silica, 36-1 magnesia, and 84 water. Presnitz in Bohemia, and the Greiner in Tyrol. Monradtte. — Massive, foliated, translucent, and yel- lowish-gray. H. = G ; G. = 3-2G7. Has nearly the same Family^ VILLARSITE — BRUCITE. 14Y composition, but with half the water. B.B. infusible. Bergen, Norway. FicrojphyU. — Dark-green, foliated. G. = 2*73 ; H. = 2*5. B.B. infusible, but becoming white. Is similar or altered augite. Sala. 85. ViLLARSITE.— 2 Mg' Si+H. Ehombic ; crystals P . OP, meeting at 136° 32' ; often in macles of three ; also granular. Fracture uneven. H. = 3 ; G. = 2-9 ... 3-0. Translucent. Greenish or grayish- yellow. B.B. infusible; decomposed by acids. Chem. com. 41 silica, 53 magnesia, with 3 or 4 iron protoxide and 2 or 3 manganese protoxide, and 6 water. Tra- versella in Piedmont. 86. Spadaite.— Mg' Si' -f 4 H. Only massive, with splintery fracture. Sectile. ^ H. = 2*5. Translucent ; weak resinous. Red ; streak white. B.B. fuses to an enamel- like glass ; soluble in con. h. acid, leav- ing slimy sihca. Chem. com. 57 silica, 32 magnesia, and 1 1 water. Capo di Bove, near Eome. 87. Gymnite, Deweylite. — Mg* Si^-1- 6 H. Only massive. H. = 2...3j G. 1-9...2-2. Semi- translucent ; resinous. Pale or dirty orange-yellow. B.B. becomes dark brown, and fuses on very thin edges. Chem. com. 41 silica, 36 magnesia, and 23 water. Bare Hills near Baltimore, and Tyrol. 88. Brucite, Nemalite. — Mg H. Ehombohedral ; E 82° 22'; crystals also 2E and OE ; also fohated or columnar. Cleavage, basal very perfect. Sectile; fine laminae flexible. H. = 2 ; G. = 2-3...2-4. Translucent ; pearly. Colourless, or grayish and greenish- white. B.B. infusible ; easily soluble in acids. Chem. com. 69 magnesia and 31 water, but after exposure often contains carbonic acid and eff"ervesces. Nemalite is a fine fibrous variety with silky lustre. Swinaness in Unst, Hoboken in New Jersey, and Beresowsk in the Ural. 148 HORNBLENDE. [Hornblende **Family IX. — Hornblende. Monoclinic mostly. Distinct cleavage in several direc- tions. H. = 4...6, but generally 5, or scratch with knife j Gr. = 2-5... 4-0, but mostly high. Mostly coloured, ranging from white, through green (rarely brown), to black. Lustre vitreous, in some silky or metaUic pearly. Soluble, but not very readily, in acids; and more or less easily fusible. Chem. com. anhydrous silicates and aluminates of lime, magnesia, iron protoxide, more sparingly of soda, yttria, and manganese protoxide. The chief species are essential constituents of the igneous rocks, and form by their decom- position highly fertile soils. N.B. — Hornblende and Augite rather represent groups of mineral substances than single species. They are best distinguished, when imperfectly formed, by the cleavage and angles of the prisms. **89. Hornblende, / R Si = [EO . SiO'], or Amphibole. t 6 R Si Sf. Monoclinic; C = 75° 10', ooP 124° 30^ P 148° 30'. The crystals short and thick, or long and thin prismatic, formed especially by ooP {M) and ooP^oo {x), and bounded on the ends chiefly by OP and P {r) (Fig. 129). Macles e common, with the chief axis the twin axis. Very often radiated, fibrous or columnar, or granular. Cleavage, prismatic along ooP 124|° very perfect, orthodiagonal and clinodiagonal very imperfect. H. = 5...6 ; G. = 2*9. ..3*4. Pellucid in all degrees ; vitreous, but some- Fig. 129. ^^^^^ pearly or silky. Colourless ; white, but usually some shade of gray, yellow, green, brown, or black. B.B. fuses, generally intumescing and boiling, to a gray, green, or black glass. Those containing most iron are most fusible, and are also partially soluble in hydro- chloric acid, which scarcely affects the others. Chem. com. very variable ; the silica is partly replaced by alumina, specially in the green or black varieties ; R is chiefly Mg, Ca and Fe. The lime is the most constant element. Family.] HORNBLENDE. 149 in most from 10 to 12, magnesia and iron protoxide replace each other, the one increasing as the other diminishes. With 4 Si and E = 2 Mg+ 1 Ca -f 1 Fe, the average com. is 53-6 silica, 17-8 magnesia, 12*5 lime, and IG'l iron prot- oxide ; but analyses give 40 to 60 silica, 0 to 17 alumina, 0 to 30 magnesia, 0 to 15 lime, 0 to 36 iron protoxide (or peroxide), 0 to 4 manganese protoxide, 0 to 8 soda, 0 to 3 potash, and 0 to 1*5 fluorine, with a little water. The more remarkable varieties are — 1. Tremolite, Grammatite, or Calamite. — 3 Mg Si + Ca Si, with 58-35 silica, 28-39 magnesia, and 13-26 lime. White, gray, green, in long prismatic crystals, often striated longitudinally. Pearly or silky ; semitrans- parent or translucent. B.B. fuses readily to a white or nearly colourless glass. Sweden, the Alps, Pyrenees, Silesia, Siberia, North America, Cornwall, Cumberland, Glen Tilt, Glenelg, Tiree, Portsoy, Aberdeenshire, and Unst. 2. AdinoUte, Adinote, or Stmhlstein. — Colour green, inclining to black, gray, or brown. Translucent, or only on the edges. Long prismatic crystals, or radiated colum- nar masses. B.B. melts to a greenish or blackish enamel. Sweden, Tyrol, North America, Glenelg, Isle Oronsay, Loch Shin, and Aberdeenshire. 3. Asbestus, Amianthus, and Byssolite. — Fine fibrous. White, gray, or green. The fibres often easily separable, elastic, and flexible. Savoy, Tyrol, Corsica, and Unst. Rock-cork, felt-like, and swims on water ; Saxony, Sweden, Portsoy and Leadhills in Scotland. Rock-leather, flat and flexible ; Leadhills, Buck of Cabrach in Aberdeenshire, and Strontian ; and Rock-wood, near Sterzing, in the Tyrol. 4. Hornblende. — Green or black, seldomer brown or gray. G. = 3-1. ..3-3. B.B. Fuses rather easily to a yellow, greenish, or black enamel. Three varieties are distinguished. (a.) The noble or Pargasite, pale celadine or olive-green, and strong pearly or vitreous lustre ; at Pargas in Finland, Tyrie in Scotland, {b.) Common hornblende, dark leek or blackish green, opaque ] streak greenish-gray. A constitu- ent of many rocks, as in Norway, the Alps, and Scottish Highlands (Ballater, Ben Lair, East Bona), (c.) Basaltic, 150 AUGITE. [Hornblende foliated, with bright even cleavage, opaque, velvet-black ; streak gray or brown. Generally contains alumina (9 to 15) and much (5 to 11) iron peroxide; and Zirkel says often numerous microscopic grains of magnetite. In basalt and volcanic rocks ] Etna, Vesuvius, the Ehine, Bohemia. 5. Antho;phylUte. — Said rhombic and a distinct species, but very doubtful. Clove-brown to leek-green, translucent, radiating, and columnar ; pearly on cleavage planes. B.B. very difficultly fusible. In it the lime is chiefly replaced by protoxide of iron. Kongsberg and Modum, Norway, Greenland, and the United States. Arfvedsonite. — Massive and granular. Pure black, opaque ; streak grayish-green. Cleavage, very perfect along a prism of 123° 55'. G. = 3-44 ; H. = 6. Fusible in fine splinters in the flame of a candle. B.B. intumesces much, and melts to a black magnetic globule. Not soluble in acids. Chem. com. about 50 silica, 14 to 26 iron perox- ide, 24 to 12 iron protoxide, and 8 to 10 soda, with some alumina, lime, and magnesia. Greenland, Trederiksvarn in Norway, and Arendal. Umlite. — Dark-green or greenish-black, with the form of augite, otherwise like hornblende. The Ural. Is a pseudomorph. **90. AUGITE,| ESi,=:(Ca, Mg, Fe) Si, or Pyroxene, j [EO . Si 0^ - E Si 0' -f E' 0']. Fig. 130. Fi and many others (Fig. 135) ] but angles slightly variable. Prismatic, with faces striated; more rarely tabular or pyramidal. Also columnar or granular. Cleavage, prismatic along ocPoo and ocP, but imperfect ; fracture uneven, splintery. H. = 6-5; G. = 3-35. ..3-45 (or 4-0). Pellucid; vitreous or resinous. Yellow, green, brown, almost black, rarely azure-blue ; streak white. B.B. fuses easily with intumescence to a yel- lowish-gTcen or brown glass ; partially soluble in h. acid, after fusion wholly, and gela- tinises. Chem. com. 37 to 39 silica, 14 to 18 alumina, 7 iron peroxide (or protox- ide), 33 to 35 lime, and 2 to 3 magnesia, with 1 to 2 -^^^^ water. In the second for- mula the iron is taken as the protoxide. Vesuvius, AVilui Fig. 134. Family.] EPIDOTE. 167 River in Siberia, Mussa-alp in Piedmont, Egg in Norway, Wicklow in Ireland, Monaltrie in Aberdeenshire, and near Broadford in Skye, in Scotland. Gahnite, Lohoite, Gdkumite, from Gokum; Frugardite, from Finnland; Egeran, from near Eger; Cyprine, from Tellemark, Norway (azure-blue or green, contains copper, and B.B. melts easily in the inner flame to a red pearl) ; Xanthite, from Amity in New York — seem only idocrase. Used as an ornamental stone, the brown being named hyacinth, the green chrysolite, but not highly valued. -r.. (2(A1, re)Sf + 3Ca' Si,or *1 33. Epidote, Pis- J r3 /^^^ qs + CaO . Si 0^+ tazite, Thallite. r- q^q ^ jj^qj^ Monoclinic ; C. = 89° 27', ooFo) (M), a)F2 63° 1', P^oo (T) 64° 36', -P 70° 25', -Poo (r) 63° 42', as in Fig. 132 after Mohs, but Marignac and most recent authors choose another position with C. = 64° 36', when T=ooFoo, ilf= OP, r = P;oo, and ?i = P, with ooP 70°. Crys- ^. tals horizontal, prismatic, and often complex with many partial forms. Generally in druses; the faces often striated. Macles united by T; also columnar, granular, or compact. Cleavage, M very perfect, along T rather perfect. Meet at 1 1 5° 24'. Fracture conchoidal, uneven, or splintery. H. = 6. ..7 ; G. = 3-2... 3-5. Pellucid in all degrees ; vitre- ous, on cleavage adamantine. Especially green (Pistazite), yellow, and gray ; rarely red and black. B.B. fusible, and swells up to a dark-brown slag. Strongly ignited, or after fusion, all are soluble in h. acid, and gelatinise. Chem. com. variable, but, according to Kenngott and Ludwig, the second above with 38*3 silica, 27*4 alumina, 8*5 iron per- oxide, 23-9 lime, and 1*9 water in those from Switzerland; in those from Arendal, Bourg d'Oisans, and Sulzbach, with 37-2 silica, 21*3 alumina, 16*5 iron peroxide, 23*1 lime, and 1-9 water, the last basic. Arendal, Dauphin6, the Alps (Mont Blanc), Pyrenees, Greenland, the Ural, and North America. In Scotland, in syenite in Zetland, in gneiss in Sutherland, in trap in Mull and Skye, in quartz in Bona, in clay-slate in Arran, and in porphyry in Arran and Glen- coe. Fuschkinite from the Ural, Withamite from Glencoe, 168 ZOISITE — AXINITE. [Garnet in minute bright-red crystals; and BucMandite, in small black crystals, from Achmatowsk in Ural, are varieties ; also Piedmontite or Manganese-epidote. — With much man- ganese-peroxide (14 to 20). Dark violet-blue or reddish- black ; streak cherry-red. H. = 6*5 ; G. = 3 '4. B.B. melts easily to a black glass. St. Marcel. 133a. ZOISITE. Ehombic according to Descloizeaux ; with ooP 116° 16' to 117° b\ 00 P2 145° 28', and other forms. Cleav- age, brachydiagonal very perfect. But chiefly in large indistinct, embedded crystals, strongly striated, or foliated and columnar. H. = 6 ; G. = 3-2... 3*4 AVhite, yellowish, or brownish-gray. B.B. intumesces and forms a white or yellow porous mass, and on the edges fuses to a clear glass. Chem. com. like epidote, with 42 silica, 32 alumina, and 26 lime, and a little (2 to 7) iron oxide and magnesia. Is thus either a dimorphous form, or, as others think, monoclinic and a variety of epidote. Sterzing, Tyrol, Sau Alpe in Carinthia, the Ural, and Connecticut. Thulite, rose or peach-blossom red, from Souland in Norway, is similar. Triclinic. Crystals usually very unsymmetrical (Figs. 137 and 138), with u to P=135° 3i; u to r=115° 38^ P to r=134° 45'; attached singly, or in druses. Also laminar or broadly radiated. Cleavage, distinct along planes truncating the sharp edges between P and u and P and r. H. = 6 '5 . . . 7 ; G. = 3 '2 . . . 3 '3. Pellucid ; vitreous. 134. AXINITE. — (Al, B) Si -f 2 (Ca, Fe) Si, or [WO' . SiO' + 2 (EO . SiO')]. Fig. 137. Fig. 138. Family.^ GLAUCOPHANE — CYANITE. 169 Clove-brown, inclining to smoke-gray or plum-blue, but often cinnamon-brown in one direction, dark violet-blue in a second, and pale olive-green in a third (trichroism). B.B. colours flame green ; intumesces and fuses easily to a dark-green glass, becoming black in the ox. flame ; not soluble in h. acid till after ignition, when it gelatinises. Chem. com. 45 '9 sihca, 5-9 boracic acid, 17-5 alumina, 9-3 iron (with manganese) protoxide, and 21-4 lime. Bonrg d'Oisans in Dauphme, Botallack and other mines in Cornwall, Kongsberg, Aren- dal, Nordmarl: in Sweden, Pyrenees, St. Gotthard, Tyrol, Thum in Saxony {Thummerstein), the Ural, and North America. 1.35. GLAUCOPHANE.— 2 Al Si' + 9 E Si. Ehombic or monoclinic, only indistinct, thin, four or six sided prismatic crystals, or granular. Cleavage, pris- matic distinct; fracture conchoidal. H. = 5*5; = 3'1. Translucent or opaque ; vitreous or pearly. Gray, mdigo- blue, or bluish-black. B.B. becomes yellowish-brown, and fuses readily to an ohve-green glass ; partly soluble in acids. Chem. com. 56-5 silica, 12 '2 alumina,^ 10*9 iron protoxide, 0-5 manganese protoxide, 8 magnesia, 2 '3 lime, and 9 '3 soda. Island of Syra. Similar are— mchtijne.—M.2iSsiYe; black. B.B. fuses to a black enamel; not aff'ected by acids. Wichtis in Finnland. Violan. —UsisdYe ; opaque, resinous. Dark violet-blue. B.B. fuses easily to a clear glass. St. Marcel in Piedmont. Family XII. — Cyanite. Triclinic or rhombic, often in long prismatic forms. , H. = 5...7-5; G. = 2-9. ..3*8. B.B. infusible; insoluble in acids. "Some show fine colours and high vitreous lustre. They are chiefly anhydrous silicates of alumina. Occur especially in the crystalline strata. **136. Cyanite, Disthene.— A1 Si = [Al'O' . SiO"]. Triclinic. Generally broad prismatic lengthened crys- tals (Fig. 139) formed by two faces {M, T) M : T 106 15\ M:i 145° 41', P : ilf 93° 15'. Macles common, united by 'ilf. Also even, curved, or radiated. Cleavage, along 170 SILLIMAXITE — . -AXDAirSITE. [Cyo.nite the prisms very (or less) perfect ; brittle. H. = 5 on ^ p cleavage-planes, on other faces = 7 ; G. 3*5. ..3"7. Pellucid, vitreous ; on cleavage pearly. Colour- less, or blue, gi^av. green, yellov, or red. Xot afiected by acids. B.B. infusible. Chem. com. 36'9 silica, and 63-1 alumina. St. Gotthardt, Fig. 139. Tyrol {Bhcptlzlte), Pontivy in Prance. Bohemia, Xigg near Aberdeen, Botriphnie in Bann'sliire, and Hills- wick in Zetland. 137. SiLLDLixiTE. — ±\ Si, or Sil Ehombic. :cP 111'. Crystals long and slender: also fibrous or columnar. Cleavage, macrodiagonal highly per- fect. H. = 7...7-5: G. = 3'2...3':26. Translucent, resin- ous, on cleavage vitreous. Grayish-brov^n. clove, or hair- brown. B.B. infusible ; not afiected by acids. Chem. com. like andalusite. Chester and ^S^orvich in Connecticut, Tvedestrand in Xorway. Monrolite. from Monroe. Xew York: XenoUfe, Finnland : BucJioJzito. Fi^^i-'Iife. Bamlite, from Bamle, in Xorway, seem the same j U'orthite, an altered variety. *13S. AxDALrsiTE.— "i^l Si. or Al' Si'. Ehombic : aP 90' 50'. Px 109' -i'. Crystals x P . OP, or wiih Px (31. F. (Fig. 140 ); prismatic, attached or embedded : also columnar, or granular. Cleav- age. ccP rather indistinct: traces along aPx , :cpx and Px . Fracture uneven, splintery. H. = 7...7-5: G. = 3T...o-2. Pellucid; vitreous. i Gray, green, red, or blue. B.B. infusible ; not i :^'. i.KK afiected by acids. Chem. com. in most like cya- nite, but in some 39*6 silica and 60"-i alumina, with 1 to 2 iron peroxide. Andalusia, Lisens in T}to1. Penig in Saxony. AVestford in Massachusetts, Litchfield in Connecti- cut ; and Botriphnie in Banft shire, Pluntly and Tyrie in Aberdeenshu-e, and Killiney Bay in Wickluw. N.B. — Assuming AlSi as the true formula for cyanite, sillimanite, and andalusite, then this substance is tri- morphous. Family.] STAUROLITE. 171 Fig. 141. H. = 5...5-5; G. = 3-0. Dirty or pale gray, yellow, or red. Occurs imbedded m clay-slate, and often appears like four crystals separated by a black cross (Fig. 141). Fichtelgebirge, Brit- tany, the Pyrenees, Sierra Morena, Wolfscrag near Keswick, and on Skiddaw in Cumberland ; near Balahulish in Argyleshire, Boharm in Banffshire, and in Wicklow. *139. STAUROLITE, Staurotide.— (^1, Fe) Si+(Fe,Mg) Si. Khombic ; oo 128° 42', Poo 70° 46'. Crystals ooP (M) . 00 Poo (o) . OP (p). Macles very common, like Figs. 142 or 143. Cleavage, brachydiagonal perfect, traces along ooP; . x_ Fig. 142. Fig. 143. fracture conchoidal, or uneven and splintery. H. = 7 ; G. = 3 -5 ... 3 -8. Translucent or opaque ; vitreous, inchnmg to resinous. Eeddish to blackish brown ; streak white. B.B. infusible ; not affected by h., partially by s., acid. Chem com. of a pure variety about 30 silica, 48-5 alumina, with 5-5 iron peroxide, and 12*5 iron protoxide, with 3*5 mag- nesia, but analyses vary greatly from microscopic mixture with other minerals. A specimen from Aberdeenshire con- tained quartz, brookite, magnetite, and mica. St. Got- thardt and Greiner in Tyrol, Finisterre, Pyrenees, Spam, the Ural, and in North America; in Scotland, Bixeter Yoe in Zetland, near Huntly, Aberdeenshire, and the Hebrides. 172 DIASPORE — PERICLASE. [Gem 140. DiASPORE,— Al H, or [AlW . H'^O]. Rhombic ; jxP 129° 47', broad, indistinct prisms, chiefly of ooPoo , bounded by the curved faces of P (Fig. 144). Usually thin foliated or broad radiated. Cleavage, brachydiagonal highly perfect ; very brittle. H. = 6; G. = 3'3, . I'L Pellucid; vit- Fi- 144 ^^^^^ ' V^^^h on coPoo . Colourless, but gene- rally yellowish or greenish white ; also violet-blue. Insoluble in acids. B.B. infusible, but some decrepitate into small white scales. Chem. com. 85 alumina and 15 water. Rare. Ural and Schemnitz, Broddbo and St. Got- thardt. 141. Hydralgilite.— Al H', or [AlW. 3 ffO]. Monoclinic j in six-sided tables of OP. ooP. ooP'oo , or granular scaly. Cleavage, basal very perfect. H. = 2*5... 3; G. = 2-3...2-4. Translucent; vitreous; pearly on OP. Colourless, but greenish or reddish white. Slowly soluble in warm acids. B.B. exfoliates, and gives out a strong light, but is infusible. Chem. com. 65-5 alumina and 34*5 water. Near Slatoust in the Ural. Stalactitic, greenish or grayish white (GMsite); Richmond, Massachusetts, Villa Rica in Brazil. 142. Periclase. — Mg. Tesseral, minute octahedrons or cubes. Cleavage hexa- hedral perfect. H. - 6 ; G. = 3-6. ..3-75. Transparent; vitreous. Dark-green. B.B. infusible ; powder soluble in acids. Chem. com. magnesia, with 5 to 8 protoxide of iron. Monte Somma. Family XIII. — Gems. All very hard, H. :=7...9, or scratch quartz, except a few = 6, which are scarcely true gems; G. = 2*6. ..4*7, but mostly high in the finest. Insoluble in acids, and infusible B.B. in the true gems. These have a high lustre, brilliant colours, and take a fine polish, and are therefore much valued. They are, however, rare, and generally small. Chem. com. variable, but mostly simple. Chiefly occur in the older igneous or metamorphic rocks. Family.] ZIECON — SPINEL. 173 *143. Zircon.— Zr Si = [Zr 0\8i 0']. Tetragonal; P 84° 20'. Crystals, coP.P, often with 3 P 3 ; also ooPoo . P, or ooPoo (s) . c«P (/) . P (P) . 3 P 3 (x) . Pco (/^) . 4 P 4 (y) . 5 P 5 (z) (Fig. 145), chiefly pris- matic or pyramidal, and in rounded grains. Cleavage, along P and ooP, both rather imperfect ; fracture con- choidal or uneven. H. = 7*5 ; G. = 4-0... 4'7. Transparent to opaque ; vitreous, often adamantine. Barely white, generally gray, yellow, green, or frequently " red and brown. B.B. loses its colour, but is infusible ; not affected by any acid except con. s. acid, after long digestion. Chem. com. 66-3 zirconia, and 33*77 silica, with 0 to 2 iron peroxide as colouring matter. Southern Norway, Ilmen Mountains, Arendal, Sweden, Carinthia, Tyrol, Ceylon, and North America ; in Scotland, Strontian, and Scalpay in Harris. The colourless varieties are sold for diamonds. The more brilliantly coloured are named hyacinth. 144. Malakon. — 3 Zr Si + H. Tetragonal ; P. 83° 30'. Crystals, like zircon. H. = 6 ; G. = 3-9. ..4-1. Opaque ; resinous or vitreous. Internally bluish-white, but on the surface mostly brownish, reddish, yellowish, or blackish. Chem. com. zircon, with 3 per cent, water ; probably not essential. Hittero in Norway (Mala- kon.) (ErstecUite from Arendal, and Tachyaj^haltite from Krageroe, are probably altered zircon. *145. Spinel.— MgAl = [Mg 0 . AP 0']. Tesseral; 0 alone or predominating, ooO and 303. Macles united by a face of 0 (Fig. 146) ; also in grains or fragments. Cleavage, octahedral imperfect ; fracture con- choidal. H. = 8 ; G. = 3-4... 4*1. Transparent to opaque; vitreous. Red, blue, green, and black ; streak white. B.B. infusible and unchanged, Chem. com. 72 alumina and 28 magnesia ; but some with a little iron protoxide or per- 174 AUTOMOLITE — COEUNDUM. [Gem, oxide, and tlie red varieties 1 to 5 chrome. Varieties are — Sjjlnel or Sinnel riilij, rose-red {Balas ruhij), yellow or 20 iron protoxide; Candy in Ceylon {Candite or Zeilanite), Monte Somma, Monzoni, Arendal, Bohemia (Eercijnite), the Ural, and New York. Chlorosjjinel, grass-green, with a yellowish- white streak ; G. = 3'd9; Slatoust in the Ural. 146. AuTO^iOLiTE, Gahnite. — Zn kl. Tesseral : 0, alone or with ocO, also cubes and macles like Fig. 1-46. Cleavage, 0 perfect; brittle, with con- choidal or splinteiy fracture. H. = 7'5...8 ; G. = 4'3...4-9. Opaque or translucent on the edges ; vitreous, inclining to resinous. Dark leek-green to blackish green and blue ; streak gray. B.B. unchanged; not affected by acids or alkalis. Chem. com. 56 alumina and 44 zinc oxide, but with 4 to 6 protoxide of ii^on, and 2 to 5 magnesia. Fah- lun, Broddbo, Haddam in Connecticut, and Franklin in Xew Jersey. Lijsluife, yellowish-brown, with manganese, from Sterling, Massachusetts ; and Kreittonite^ brown, from Bodenmais, are similar. *U7. Corundum.— Al = [AP 0']. Hexagonal, rhombohedral ; isomorphous with the per- oxides of iron and chrome ; R 86° 4'. Crystals chiefly of a.P2 (.s), OR (o), R {P), are pyramidal (Fig. 147), pris- matic (Fig. 148), or rhombohedral. IMacles common, united by a face of R. Cleavage, rhombohedral along R, and basal more or less perfect. Extremely tough, and difficultly frangible. II. - 9 ; G. = 3-9...4'2. Transparent Fig. 1-46. orange-red {Euhkelle), violet (AI- maiidine riihy) or brown ; G. = 3 "5 2; from Ceylon, Ava^ and the East. Much prized as ornamental stones. ScippMr'ine, — Pale sapphire- blue to greenish or reddish blue ; G. = 3'4.".3-7; with 4 per cent iron protoxide ; Aker in Sweden, Greenland, and North America. Fleonaste, dark green or blue and black; G. = 3-65. ..3-8 ; with 8 to Family.'] TOPAZ. 175 or translucent ; vitreous, or pearly on OE. Colourless and white, but generally blue, red, yellow, brown, or gray. B.B. Fig. 147. Fig. 148. unchanged. Chem. com. alumina, with a minute propor- tion of peroxide of iron or other colouring matter. Varieties are : — (1.) Sapphire, highly transparent, very imperfect cleavage and conchoidal fracture ; colourless, blue {Salamstein), seldom er green, yellow, red (Oriental rubies), or brown ; Ceylon, Ava, Pegu, Miask, Slatoust, Bilin in Bohemia, and Expailly in Auvergne. (2.) Oonin- dum, rough crystals or foliated, less transparent and duller colours ; Malabar, Ceylon, Ava, Canton in China, Siberia, St. Gotthardt, and Piedmont. Some (Asteria or star sap- phire) show a bright opalescent star of six rays. Eecently crystals (one of 300 lbs. weight) of gray corundum with blue sapphire in the interior at Macon in North Carolina. (3.) mantine spar, with distinct cleavage, hair-brown, and ada- mantine ; Gellivara, Ural, Malabar, and North America. (4.) Emery, compact, dimly translucent, and gray or indigo- blue ; Asia Minor near Smyrna, Naxos, Spain, Saxony, and Greenland. Sapphire and rubies are highly valued as or- namental stones ; emery as a polishing material. 148 Topaz J 5 Si + (A1 F + Si P), or Rhombic; ooP (ilf) 124° 17', 2Poo {n) 92° 42', a)P2 {I) 93° 14', P (o), and numerous other forms. Crystals 176 LEUCOPHANE — CHRYSOBERYL. [Gem always prismatic (Fig. 149), often hemimorphic, and the prisms finely striated ; also granular. Cleavage, basal very perfect, traces in other directions, especially M and / in the Scottish varieties ; fracture conch oidal or uneven. H. = 8 ; G. = 3-4... 3 -6. Trans- parent to translucent on' the edges ; vit- reous. Colourless, but yellowish, reddish, or greenish white, honey-yellow, hya- cinth-red, and asparagus - green. Be- comes electric from heat or friction. B.B. infusible. Not affected by h. acid, but by long digestion in s. acid gives traces of fluorine. Chem. com. essen- tially Al Si with part of the oxygen replaced by fluorine; or nearly 33*16 silica, 56*70 alumina, and 17*50 fluorine (= 107*36). Brazil, Siberia, Ceylon, New Holland, Peru, Connecticut, Bohemia, Saxony, and Cornwall (St. Michael's Mount), Mourne Mountains in Ireland, Cairngorm Moun- tains in Aberdeenshire (one crystal nineteen ounces). The common or coarse columnar named Pyropliysalite, at Finbo, and Broddbo near Fahlun. Topaz is valued as an orna- mental stone. The purest from Brazil, when cut in facets like the diamond, closely resemble it in lustre and bril- liance, but are easily known by their electricity. Pycnite, Schorlite. — Massive. H. = 7.5; G. = 3*49... 3*54. Translucent ; vitreous. Straw-yellow to reddish- white. Variety of topaz. Altenberg in Saxony, and Schlaggenwald and Zinnwald, Durango in Mexico. 149. LEUCOPHANE.— 6 Ca Si + 3 GP Si -f 2 Na F. Rhombic ; ooP about 91° ; but crystals rare. Cleavage, basal perfect. H. = 3'5...4; G. = 2*97. In thin splinters pelhicid and almost colourless ; in thicker pieces wine- yellow or olive-green ; vitreous or resinous. B.B. fuses to a pale violet-blue bead. Melino^liane is a variety. Both near Brcvig in Norway. 150. CjiRYSOiiKUYL, Cymophane. — Gl Al. Rhombic; P with polar edges 86° 16' and 139° 53'. Family.'] CHRYSOBEPtYL — EUCLASE. 177 Crystals of ooPoo (1/) ooP^ (T) . Poo {{), or this with ooP2 {s\ and also with P {o) (Fig. 150), are short and broadly columnar, or thick tabular with vertical striae. Macles very common, united by a face of P oo . Cleav- age, brachy diagonal imperfect, macrodiagonal more so; fracture conchoidal. H. = 8*5 G. = 3'68...3-8. Transparent or translucent ; vitreous, sometimes resinous. Greenish- white, leek-green, olive-green, and greenish- gray j sometimes with a bluish opalescence, or beautiful trichroxsm. B.B. infusible; not affected by acids. Chem. com. 80 alumina, and 20 glucina with 3 to 4 protoxide of iron. Brazil, Ceylon, India, Haddam in Connecticut, and Ural. 151. EucLASE.— 2 Gl Si + H ^1. Monoclinic; G 79° 44'; ooP«2 115", 3P^3 {t) 105° 49'. Crystals specially of odP^2 . ooP^oo . {T) . 3P^3, and many other forms (Fig. 151). Cleavage, clinodiagonal highly perfect, less so in other directions. Very brittle and fragile ; fracture conchoidal. H. ^^7.5; G. = 3'0...3'1. Transparent; splendent vitreous. Pale mountain-grean, passing into Fig. 150. Fig. 151. yellow, blue, or white. B.B. intumesces, becomes white, and melts in thin splinters to a white enamel. Not affected by N 178 EMERALD— PHENAKITE. [Gem M Fig. 152. acids. Cliem. com. about 42 silica, 35 alumina, 18 glucina,and 6 water. Peru and Brazil, and Southern Ural, but very rare. *152. Emerald, Beryl.— il Si'+ 3 Gl Si. Hexagonal; P 59° 53^ Crystals of ooP . OP, and 00 P . OP . P (if, F, X, Fig. 152), are prismatic, generally with vertical stri^. Cleavage, basal rather perfect, ooP imperfect, jj 7.5^ g . G-. = 2-6...2-8. Transparent or translucent ; vitreous. Colourless or white, but generally green, some- times very brilliant, also yellow, and smalt-blue. B.B. melts with difficulty on the edges to an obscure vesicular . p glass. Not affected by acids. Chem. com. 67-5 silica, 18-7 alumina, and 13'8 glucina, with 0'3 to 3 iron peroxide, and 0*3 to 3*5 chrome oxide in the rich green emerald. Emerald, bright green; G. = 2'710... 2*759 ; occurs in Muso Valley near Bogota, also in Salzburg and the Ural. Beryl, or Aquamarine, colourless, or less brilliant; G. = 2-677. ..2-725 ; near Mursinsk, and ^Terts- chinskin Siberia, Salzburg and Brazil ; in the United States, where at Grafton, between the Connecticut and Merimac, crystals 4 to 6 feet long, and weighing 2000 to 3000 lbs., occur ; Mourne Mountains in Ireland ; Mount Battoch and Cairngorum in Scotland. Common beryl at Fahlun in Sweden, Fossum in Norway, Limoges in France, Eabenstein in Bavaria ; Nigg Bray and Eubislaw near Aberdeen {Damd- sonite). Emerald and beryl are much valued as precious stones. Known from quartz by face P. 153. Phenakite.— Gl' Si. Hexagonal and tetartohedral ; E 116° 36''. Crystals E. odP2, or ooP2 . fP2 . E. (n, s, P, Fig. 153). Macles with parallel axes and intersecting. Cleav- age, E and 00 P2 not very distinct ; fracture con- choidal. H. = 7.5. ..8 ; G. = 2-97. Transparent or translucent ; vitreous. Colourless, and Avine- yellow or brown Avhen fresh, but soon lost on exposure. B.B. infusible ; not affected by acids. Fig. 153. ^j^^^^^ ^^^^^^ ^.^.^^^^ ^^^^^ glucina. Ural, Ilmen Mountains, Framont in Alsace. Family.'] COEDIERITE. 179 Fig. 154. ^154. GoRDiERiTE, f Sf + 2 (Mg, Fe) Si, or lolite, Dichroite. \ [2 AF 0^ 3 Si 0' + 2 (Mg 0 . Si 0']. Rhombic; ooP 119° 10', middle edge of P 95° 36. Crystals coP {T) . ooPoo (/) . OP {M\ and this with ooPoo {h\ 00 P3 {d\ Pcx) (n\ and ^P {s) (Fig. 154); short, pris- matic. Cleavage, ooPoo ; rather distinct, traces along Poo ; fracture conchoidal or uneven. H. = 7... 7*5 j G-. = 2'5...2-7. Transparent or trans- lucent ; vitreous, inclining to resinous. Colourless, but chiefly dark blue, or violet, green, brown, yellow, and gray, often with distinct trichroism, on OP blue, on ooPoo gray, and on ooPoo yellowish. B.B. fuses difficultly to a clear glass ; slightly affected by acids. Chem. com. 48 to 51 silica, 29 to 33 alumina, 8 to 13 mag- nesia, 1 to 1 2 iron protoxide, and 0 to 1 -5 manganese protoxide. Cabo de Gata in Spain, Bodenmais (Feliom), Orrijerfvi (Steinheilite), Nor- way, Sweden, Greenland, North America, and Siberia. Small rolled masses of an intense blue colour and trans- parent, found in Ceylon, are the Sapphire d'Eau or Luchs- sapphir of the jewellers. The following substances seem cordierite altered, or with 2 to 6 atoms water : — (a.) Bonsdorfite, Hydrous lolite, greenish-brown or dark olive-green ; ^ near Abo. {k) Ssmarkite, Ohlorophyllite, large prisms or foliated, green or brownish ; near Brevig in Nor- way, Unity in Maine, and Haddam in Connecticut, (c.) Fahlunite, Tridasite, compact, greenish-brown or black foli- ated ; H. = 2-5... 3 ; G. = 2'5.,,2'S ; Fahlun. (d.) Euronife, granular; pearly, yellowish-green; H = 3-3; G. = 2'86. Infusible and insoluble; Lake Huron, (e.) Weissite, kid- ney-shaped and ash-gray or brown; Fahlun and Lower Canada. (/.) Pyrargillite, indistinct embedded crystals, black passing into brown or red, dull resinous lustre ; H. = 3-5; G. = 2-5; Helsingfors. {g.) Finite, crystallised, or massive and laminar, with imperfect cleavage ; H. = 2..»3 ; 180 TOURMALINE. [Gem G. = 2'7...2-9 ; semitranslucent or opaque, dull or resinous, and dirty-gray, green, or brown ; B.B. fuses to a glass, sometimes clear, at other times dark-coloured ; Auvergne, Schneeberg, Penig in Saxony, in the Harz, Cornwall, Aber- deenshire, the United States, and Greenland {Gieseckite). Oosite from Geroldsauin Baden, snow-white, opaque, fragile, is similar. (k) Gigantolite ; H. = 3'5 ; G. = 2 "8 . . . 2 -9 ; opaque, dull resinous, and greenish-gray or brown. B.B. intumesces slightly, and fuses easily to a greenish slag ; Tammela in Fmnland. {i) Fraseolite, lamellar and green ; Brevig in Norway, **155. Tourmaline, f nR Si -f Si = Schorl. t [n(R' 0' . Si 0') + 3 RO . Si 0']. Ehombohedral ; R 133° 10^ Crystals of OR {k'), - JR (155°), R (P), - 2R (103° 30 (o), ooP2 (s), and ooR (/), usually long prismatic, striated, and often as if broken. They are remarkable for hemimorphism, ooR appearing as a trigonal prism (Figs. 155, 156); also radiating, columnar, Fi- 155. Fiff. 150. or fibrous. Cleavage, R and ooP2 both imperfect; frac- ture conchoidal or uneven. H. = G'5...7-5 ; G. = 3...3-3. The black opaque, the otliers pellucid ; vitreous. Colour- less, but gray, yellow, green, blue, red, brown, and most frequently black. Often several colours in layers perpen- dicular, or parallel to the axis. By friction acquires posi- tive, by heat polar electricity ; powder white, often mag- Family.'] TOUKMALINE. 181 netic. B.B. some fuse, others only intumesce, and some both fuse and intumesce. Powder not soluble in h., only imperfectly in s. acid. Chem. com. very complex, but, according to Eammelsberg, with much general agreement. They all contain water chemically combined, also fluorine from 0*3 to O'S per cent (seldom more, 1*2 ; seldomer less), and the iron only as the protoxide. They are all one-third silicates (Drittelsilicate), but in two divisions : — I. = 3 R Si + Si with 3 R = 2 '^1 + B 11. - 8 S Si + Si with 8 S= 6 'A1+ 2 B and E consisting of Mg, Ca, Fe, Mn, and of N"a, K, Li, and H in variable proportions. I. is by far the more common, and includes the yellow, brown, and (apparently) black varieties. They contain 32 to 34 alumina, and some yellow or brown varieties are almost free from (1 per cent or less), others, the black, contain much (5 to 17 per cent) iron peroxide. II. includes the colourless, pale green, and transparent varieties, or noble tourmaline, with no iron, or almost none, also very little manganese and magnesia, and 42 to 44 alumina; also lithia in determinable amount (to 1*2). Isomorphous mixtures of the two divisions occur, and even parts of the same crystal vary in composition as in colour. Analyses give boracic acid 7 to 13, magnesia 1 to 15, lime I'G or less, soda 1 to 2*4, potash under 1, and water 1 to 3. Black varieties are the most common, and known as Schorl, the red as Rubellite, the colourless as Achroite. The finest transparent varieties or noble tourmalines come from Ceylon, Siberia, and Brazil. The dark blue or Indicollite occurs chiefly in Utoe. Large crystals of the dark opaque varieties occur in Greenland, Arendal, the Tyrol, and various parts of North America. In England, Bovey in Devonshire and St. Just in Cornwall are well- known localities ; and in Scotland large prisms, often curved or broken, abound in the granite of Aberdeenshire. Tourmaline is not much valued as a gem, the colours being rarely pure. Zeuxite seems only tourmaline. 182 CHEYSOLITE. [Gem *156. Chrysolite, Olivine, Peridot. -j^ ^ '^iO'\ Ehombic; ccP [a) 130^ J', Px (J) 76= 54^ 2Pco (A-) 80° 53'; also ocPoo (J/), ocPoo with P Q;), OP (Fig. 157). The crystals are frequently prismatic and embedded ; also massive and granular. Cleavage, ccPx rather distinct; fracture conchoidal. H. = 6*5...7 ; G. = 3*3...3'5. Transparent or trans- lucent ; vitreous. Olive-green, also yellow and brown, rarely colourless. B.B. infusible, except some ^vith much iron ; soluble and gelatinising in acids. Chem. com. 38 to 43 silica, 43 to 51 magnesia, 8 to 18 iron protoxide, with a little manganese. Chri/solite is the fine green, transparent and crystallised varieties from the East, Esne in Egypt, and Brazil. Olivine, the darker and less pellucid, from Yesumis, Unkel on the Ehine, the basalts of Germany, and the trap of Arthur Seat and other parts of Scotland ; also in meteoric iron, as in the mass found by Pallas in Siberia, and in that of Otumpa in South America. Used as an ornamental stone, but not much valued. - The following seem varieties or mixtures : — Fosferite, colourless, from Monte Somma ; and Boltonite, greenish or bluish gray, from Bolton, Massachusetts, have only 2 to 3 iron protoxide. Eyalosiderite. — Brown or yellow, very ferruginous (30 Fe) and metallic-looking; H. = 5 ; G. = 2-875 ; in other re- spects like oli^-ine ; Kaiserstuhl in the Breisgau. Chiisite, Limbelite, and Tautolite; Lake Laach. Batrachite, greenish- gray or white, translucent ; Eizoni Mountain, Tyrol. Mon- ticelUfe, transparent, colourless, or yellowish ; but ooP 133° 6', 2 Poo 82°, is probably distinct; Vesuvius. Fayalite. — Crystalline, columnar and foliated, but often as if fused. Greenish or pitch-black, brownish or brass- yellow, with a resinous metallic lustre. H. = 6*5 ; G. = 4*0 ...4*15. Partly soluble in h. acid. Chem. com. Fe' Si Family.] CHONDRODITE. 183 with 29 '4 silica, 70*6 iron protoxide, but 2 to 8 manganese protoxide. Fayal and Mourne Mountains. Knehellite. — Massive, opaque, gray, green, brown, or red. Chem. com. 32*5 silica, 32 iron protoxide, and 35 manga- nese protoxide. Ilmenau and Dannemora. Tephroite. — Granular, with two cleavages at right angles. H. = 5*5; G-. = 4...4*12. Lustre adamantine. Ash-gray, with reddish-brown tarnish. Chem. com. 70 manganese protoxide and 30 silica. Franklin and Sparta, New Jersey. 157. Chondrodite, Maclurite, Brucite, -j^^s g -2 Humite. ) ^ ^ * Ehombic ; P middle edge 156° 38', polar edges 131° 34' and 54° 28', but crystals often monoclinic in character or indistinct ; chiefly in round grains or granular. Cleavage indistinct ; fracture imperfect conchoidal. H. = 6*5 : G. = 3*1 5... 3*25. Transparent or translucent; lustre vitreous or resinous. Yellow, red, brown, green, and almost black ; streak white or yellowish. B.B. infusible, or only on very thin edges ; decomposed by acids. Chem. com. silicate of magnesia, with part of the oxygen replaced by fluorine in various proportions, but without influence on the forms. Von Eath finds three types of crystals with two axes constant, the third varying as 7 : 5 : 9. The chondrodite of Pargas belongs to the second type, the Humite mostly to the third, the first and second being rare on Vesuvius. He gives for types I., II., HI, from Vesuvius, silicium 17 '2 4, magnesium 36*94, fluorine 2'57, oxygen 43*25 ; in type II., from Sweden, silicium 17*00, magnesium 36*43, fluorine 4*94, oxygen 41. Chondrodite occurs at Pargas in o Finnland, Aker and Gullsjo in Sweden, Sparta in New J ersey, and Orange County in New York ; also in Saxony, and on Loch Ness in Scotland. Humite on Monte Somma. Family XIV. — Metallic Stones. Crystallisation predominantly rhombic ; some tesseral or monoclinic ; but many massive, or products of decompo- sition, and thus rather metallic clays or rocks. The crys- talline species are rather hard, — H. = 5*5... 6*5 ; and with 184 LIEVRITE — ANTHOSIDERITE. [Metallic Stones G. = 3*6 . . .5-6. Those with high specific gravity are mostly infusible B.B., the others fusible. Most are soluble in acids, often gelatinising. They are chiefly silicates, with a metallic base, and thus an intermediate group between the true stones and the metallic ores. Often opaque, and black or brown and yellow. They occur especially in the igneous and metamorphic rocks, or in metallic veins, and chiefly those of Scandinavia and the Ural. n58 Lii^VRiTE Yenite ( Si+ 3 (Fe Ca)^ Si + H = LIEVRITE, Yenite,^ .-p^. ^3 ^ g.Q2 4. 3 (2 RQ . Ilvaite. SiO^) + ffO.] Ehombic; P (0), polar edges 139"^ 30' and 117° 27 \ ooP 112° 38', Poo (d) 112° 49' ooP2 (s) 106° 15'. Crystals (Fig. 158), are long prismatic and vertically striated ; also radiated columnar or fibrous. Cleavages several, all imperfect ; brittle. H. = 5 -5... 6; G. 3*9...4-2. Opaque, resinous or imperfect metallic. Brownish or greenish black ; streak black. B.B. fuses easily to a black magnetic globule ; soluble in h. acid, forming a yellow jelly. Chem. com. 29*3 silica, 19-6 iron peroxide, 35*2 iron protox- ide, 13*7 lime, and 2'2 water. Eio in Elba, Fossum,Kupferberg, Ehode Island, and Green- land. WelirUte, iron-black, with greenish- gray streak, and B.B. difficultly fusible, is a variety; Hungary. 159. HisiNGERiTE, Thraulite.— Pe' Si'+2 Fe Si+10 H. Eeniform, or in crusts. H. = 3-5...4; G. = 2-6...3. Opaque ; resinous. Brownish or bluish black ; streak liver or yellowish brown. B.B. fuses with difficulty ; soluble in acids, leaving slimy silica. Chem. com. very various, but 32*5 silica, 33*5 iron peroxide, 15'1 iron protoxide, and 19 water, in the Thraulite from Bodenmais. Also Gillinge, Eydarhyttan in Sweden, and Breitenbrun {Polyhydrite), 1 60. Antiiosiderite. — Fe" Si' + 2 H. Fine fibrous or flower-like ; very tough. H. = 6'5 ; G. — 3. Opaque or translucent ; silky. Ochre -yellow to Family.] KONTEONITE — EULYTINE. 185 yellowish-brown. B.B. becomes reddish-brown, then black, and fuses with difficulty. Soluble in h. acid. Chem. com. 61 silica, 35 iron peroxide, and 4 water. Minas Geraes. 161. NoNTRONiTE.— ^Fe Si' + 5 H. Massive. Fracture uneven. H. = 2...3 ; G. = 2, ..2"3. Opaque; dull or glimmering; streak resinous. Straw- yellow, yellowish-white, or siskin-green. B.B. decrepitates, becomes black and magnetic, but without fusing ; soluble, and gelatinises in warm acids. Chem. com. nearly 43 silica, 36 iron peroxide, and 21 water, with 3*5 alumina and 2 magnesia. Nontron in France, Harz, and Bavaria. Chloropal is similar, but B.B. brown and infusible. Unghwar in Hungary, and near Passau. Finguite, sectile ; H. = 1 ; feels greasy ; and B.B. fuses on the edges ; is also a silicate of iron oxides with water ; Wolkenstein in Saxony, near Zwickau, and Suhl. 162. Chloroph^ite.— (Fe, Mgf Si* + 18 H. Massive. Cleavage in two directions ; fracture con- choidal, earthy ; very soft and sectile. G. = 2-02. When first exposed translucent and pistacio or olive-green, but soon changes to brown or black, and opaque. B.B. melts to a black glass. Chem. com. of a specimen from Faroe, 32-85 silica, 22*08 iron protoxide, 3*44 magnesia, and 41*63 water. Scuir More in Bum, Faroe, and Iceland; also in Fife, and near Newcastle. 1 6 3. Thorite.— Th Si + 2 H. Tesseral, but crystals rare. Massive. Fracture con- choidal; hard and brittle. G. = 4-63. ..4-8. Opaque; splendent, vitreous. Eeddish-brown, or black clouded with red ; streak dark-brown. B.B. infusible ; gelatinises with h. acid. Chem. com. essentially 73*4 thorina, 16*8 silica, and 9*8 water, but combined with very many other substances : lime, iron, manganese, magnesia, uranium, lead, tin, potash, soda, and alumina. Near Brevig. Orangite seems a variety with less water. Very rare ; Brevig. 164. Eulytine.— Bi' Si'. 202 , 202 Tesseral and tetrahedral ; and Ihe crys- 186 GADOLIXITE — ALLA^sHTE. [Metallic StoTies tals (like Fig. 9) very small, and often with curved faces. Cleavage very imperfect ; fracture conchoidal. H. = 4'5... 5 ; G. = 5 '9 . . . 6 • 1 . Transparent and translucent ; adaman- tine. Clove-brown, yellow, gray, or white ; streak white or gray. B.B. fuses readily with intumescence to a brown bead, lea^dng a yellow ring on the charcoal ; decomposed by h. acid, forming gelatinous silica. Chem. com. 16 '2 silica and 83*8 bismuth peroxide, but with phosphoric acid and iron peroxide. Schneeberg, and Braunsdorf near Freiberg. Eypochlonte or Green Iron-earth, from Schneeberg, reni- form or fine earthy ; and siskin or olive green. H. = 6 ; G. = 2'9...3. B.B. infusible. Insoluble. Is a mixture of silicate of iron and bismuth with phosphate of alumina. Eyjjochi or ite from Braunsdorf, is chiefly silica 88 per cent, with phosphate of iron and antimony. 165. Gadolinite. j J j ^f' J< 1 (Y, Gl, Fe, La)' Si. Monoclinic ; C. = 89° 28; ocP 116°, P 120° 56'; (but Ehombic, with ccP = 105° 52', Yon Path, etc.) Crystals rare and indistinct. Cleavage very indistinct, or none ; fracture conchoidal or splintery. H. = 6*5...7j G. = 4-0...4'4. Opaque or translucent on the edges j vitreous, often resinous. Black; streak greenish-gray. B.B. the conchoidal (^^itreous) varieties incandesce vividly, intumesce, but do not fuse ; the splintery varieties form cauliflower-like ramifications, but do not incandesce ; gelatinises in h. acid. Chem. com. uncertain, but 25 to 29 silica, 36 to 51 yttria, 10 to 15 protoxide of iron, 5 to 17 protoxide of cerium with lan- thanium, and 0 to 12 glucina. The cerium protoxide and glucina seem not to occur together. Hitteroe in Xorway, Ytterby, Broddbo, and Finbo near Fahlun. 166. Allanite, Cerin, Orthite.— Sr-I-R Si. Monoclinic, like epidote, but distinct crystals rare (Fig. 159), mostly columnar, or granular. Cleavage imperfect ; fracture conchoidal or uneven. H. = 6 ; G. = 3"4.,.3'8. Opaque or translucent in thm splinters ; imperfect metallic, to vitreous or resinous. Black inclining to green or brown; Family.'] TSCHEFFKINITE — CERITE. 187 streak greenish or brownish-gray. B.B. froths, and melts easily to a black or brown scoria or glass, often magnetic ; gelatinises with h. acid. Chem. com. very variable, but similar to garnet {Rams), with 30 to 35 silica, 12 to 18 alumina and iron peroxide, whilst R. includes protoxides of cerium (11 to 24), lanthanium (2 to 8), iron (4 to 21), and manganese (0 to 3*5), with lime (2 to 12), yttria (0*3 to 4), and mag- nesia (0'4 to 5). Allanite occurs in Greenland, and at Hitteroe, the Jotun Fjeld, Snarum, and ^.^ near Schmiedefeld in Thuringia ; also Bradford and Bethlem, Pennsylvania and Franklyn, New Jersey. Cerin at Eydderhyttan ; Orthite at Finbo, Fahlun, Arendal, and Kra- geroe. BucUandite, from Lake Laach and Arendal, is orthite. Pyr orthite, with carbonaceous and other matter ; , Ural' orthite, from the Ilmen Mountains, containing more alumina; Bodenite, from. Boden, Saxony ; and Bagrationite, from Achmatofsk, are only varieties. 167. TSCHEFFKINITE. Massive. Fracture flat conchoidal. H. = 5...5*5; G. = 4*5. Opaque ; vitreous, splendent. Velvet-black ; streak dark-brown. B.B. intumesces greatly, becomes porous, and often incandesces ; in the strongest white heat fuses to black glass ; gelatinises with warm h. acid. Chem. com. 21 silica, 20 titanic acid, 11 iron protoxide, 45 per- oxides of cerium, lanthanium, and didymium, and 4 lime and magnesia. Ilmen Mountains near Miask. 168. Cerite.— (Ce, E)' Si + H. Hexagonal ; OP . ooP, in low six-sided prisms, but very rare. Generally fine granular, almost compact. Cleavage, traces; fracture uneven, splintery ; brittle. H. = 5*5 ; G. = 4*9.., 5. Translucent on the edges, or opaque; dull, adamantine, or resinous. Clove-brown, cherry-red, or pearl- gray ; streak white. B.B. infusible, but becomes dirty yellow ; soluble in h. acid, leaving gelatinous silica. Chem. com. 20*5 silica, 73*5 protoxide of cerium (with didymium and lanthanium), and 6 water, with iron protoxide and lime. Bastnaes near Eidderhyttan. 188 PYEOCHLOEE — KEILHAUITE. [Metollk StoiUS 169. Tritomite.— Si, Ce, La, Ca, H. Tesseral in tetrahedrons. Fracture conclioidal; brittle. H. = 5'5: G. = 4"16...4-7. Yitreous ; translucent on tlie edges. Dark-broTvn. B.B. swells and cracks ; soluble in acids. Lamoe near Brevig. 170. PYEOCHLOEE.— [5 E 0' + 4 E (Ti. Tli) 0' + 4 Xa Fl]. Tesseral ; 0. Cleavage octahedral : brittle : fracture conchoidal. H. = 5 : G. = 4-0. . .4*4. Opaque or translu- cent ; resinous. Dark reddish-broT^Ti, or almost black, some crystals ruby-red and transparent ; streak pale- brown. B.B. becomes yellow and fuses with much difficulty into a blackish-brown slag ; the fine powder soluble in con. s. acid. Chem. com. very complex, but Eamelsberg gives the above formula for the Mask variety (E = Ce, Ca, Mg, Fe), in which he found 53"19 niobic acid, 10-47 titanic acid, 7*56 thoria (acid), 7'00 cerium protoxide, 14*21 lime, 0-'2'2 magnesia, 1'84 iron protoxide, 5'01 soda, and 3-06 fluorine. But those from Brevig and Fredriksvarn difter, and con- tain uranium protoxide. Also occurs on Kaiserstuhl and at Chesterfield, Massachusetts {Microlife). Fi/rr/iite. small orange-yellow octahedrons : H. = 6 ; is a niobate of zirconia, with iron and uranium. Mursinsk and Azores. 171. Oeestedtite. Tetragonal; P 84° 26', like zircon. H. =o'5; G. = 3-629. Opaque or translucent on the edges ; adamantine vitreous. Eeddish-brown. B.B. iufusible. Forchhammer found 19-71 silica, 2*61 lime, 2-05 magnesia, 1*14 iron protoxide, 68-96 titaniate of zirconia, 5-53 Avater. Ai^endal. ''ItS™' }^'(Ca Y)(Si,Ti) +(aFe)(Si,Tir. Monoclinic; C. = 58°, ooP=114°. Cleavages, along - 2 P intersecting at 138°. H. = 6...7; G. = 3-5. ..3-7. Translucent ; vitreous or resinous. Blackish-brown ; by transmitted light reddish ; streak grayish-yellow. B.B. fuses easily with effervescence to a black shining slag ; with borax forms a blood-red glass in the red. flame ; in powder Family.'] WOHLERITE. 189 soluble in li. acid. Chem. com. 29 '7 silica, 28*7 titanic acid, 2ri lime, 10*8 yttria, 6*2 alumina, and 6*5 iron peroxide. Near Arendal. 173. WoHLERTTE. Monoclinic j C. = 70° 45', ooP 90° 14', but crystals rare. Cleavage clinodiagonal distinct ; fracture conchoidal. H. = 5...6 ; G. = 3*41. Translucent ; vitreous or resinous. Yellow, inclining to red or brown. B.B. fuses to a yellowish glass ; easily soluble in warm con, h. acid, depositing silica and niobic acid. Analysis — 30'62 silica, 14'47 niobic acid, 15*17 zirconia, 3'67 iron and manganese protoxide, 26'19 lime, and 7*78 soda. Fredriksvarn {EuJcolite), and Brevig in Norway. 190 CALCITE. [Calc-spar Order II. SALINE STONES. Comprises minerals which, in external aspect and composi- tion, resemble (or are) the salts of the chemist. AVith a few exceptions, as rock-salt and fluor-spar, they are com- binations of the second order of two oxygen compounds. The acid component is one of the common acids, — the carbonic, sulphuric, boracic, or phosphoric acid, — not silica or alumina, as in the first order. They are almost all crj^stallised, and predominantly in rhombic or monoclinic forms, but some rhombohedral or tesseral. Their hardness is low; one 7, a few about 5, most lower. G. = l'5.,A'7. All are soluble in acids, except the sulphates (three) ; more than half in water. B.B. all fusible or decompose. Many of them are products of decomposition. Occur rather in veins than as components of rocks, and then generally constitute the whole mass. **Family I. — Calc-spar. Generally rhombohedral in crystals and cleavage. H. = 3... 4*5 ; G-. = 2'6...3*4, becoming higher as the metal- lic element increases. They are soluble and often effervesce in acids ; and become caustic or alkaline when burned. They form a series of closely-related compounds of carbonic acid with lime, magnesia, and isomorphous bases, as the protoxide of iron. Are generally white and translucent, with a vitreous or pearly lustre. **174. Calcite, Calc-spar, ) ^ ri rr^ ^r^-i 1 Q ' >- Ca C, = rCaO . CO 1. Calcareous bpar. j Hexagonal and rhomboliedral; R 105° 5' (Fig. 160); the forms and combinations exceedhigtliose of any other mineral. Among them are more than 40 rliombohedrons, especially - 135°, R, -211 79°, and 4R GG°, with OR and ooR as limiting forms ; eighty-five distinct scalenoliedrons, as R3, Family.] CALC-SPAR. 191 E2, and ^E2 ; and the second hexagonal prism ooP2, whilst _ 160. ■ Fig. 161. hexagonal pyramids are among the rarer forms. Some of the most usual combinations are ooE . — (c, g, Fig. 164) ; or - |E . ooE, very frequent ; also ooE . OE; likewise - 2E . E (/, P, Fig. 161) ; E3 . (xE . - 2E; E5 (y) . E3 (r) . E (P) . 4E (m).GoE (C) (Fig. 162); and many others, several hundred distinct combinations being known. Macles are not uncommon, especially with the systems of axes parallel (Figs. 163, 164), and others conjoined by a Fig. 162. Fig. 163. \c \c \c — K v_ ^ — Fi g. 164. face of E with the chief axes almost at right angles, 89° 8' (Fig. 82) ; or by a face of --^E, in which the chief axes form an angle of 127J° j and usually many times repeated, so that the centre crystals appear in lamellae not thicker 192 CALCITE. [CcJc-spar than paper (Fig. SI). Also occurs granular, lamellar, parallel or radiated fibrous, compact and earthy. Cleavage, rhombohedral along E very perfect and easily obtained, so that the conchoidal fracture is rarely observable : brittle. H. = 3; G. = 2-6...2'8 ; pure transparent crystals = 2*72. Pellucid in all degrees. Very distinct double refraction. Lustre vitreous, but several faces resinous, and OE pearly. 3Iost frequently colourless or white, but often gray, blue, green, yellow, red, brown, or black ; streak grayish-white. B.B. infusible, but becomes caustic and emits a bright lisht. Effervesces, and is entirely soluble in h. or n. acid. The fine powder, ignited on platina-foil over the spirit-lamp, forms a somewhat connected mass, and even adheres to the platina. Chem. com. of the purest varieties, carbonate of lime, with 4-i carbonic acid and 56 lime, or 40 calcium, 12-2 carbon, and 47-8 oxygen ; but usually contains mag- nesia and protoxide of iron or of manganese. Eemarkable specimens "of the crystallised variety, or proper calc-spar, are found in Andreasberg and other parts of the Harz (six- sided prisms), Freiberg. Tharand, Maxen, Alston Moor in Cumberland (fiat rhombic crystals), and in Derbyshire (pale yellow transparent pyramids). Certain varieties are distinguished, as — Iceland spar, remarkable for its transparency and double refraction, oc- curs massive in a trap rock in that island. Shite spar, thin lamellar, often with a shining white pearly lustre, and greasy feel : Wicklow in Ireland, Glen Tilt in Scotland, and Norway. Aphnte, fine scaly, from Hessia and Thu- ringia. Marlle is the massive crystalHne variety of this mineral, produced by igneous action on compact limestone. Paros, Xaxos, and Tenedos furnished the chief supply to the Grecian artists ; Carrara, near the Gulf of Genoa, to those of modern times. Some of the coloured marbles of the ancients were impure limestones, as the CipoUino, zoned with green talc or chlorite ; and Verde antique, mixed with green serpentine. Eain marble shows irregular markings like ruins : Val d'Arno (Florentine marble), and Bristol (Cotham marble). Lucullite, from Egypt, and Anthraconite, from Kilkenny in Ireland, are black from carbon. Luma- Family.'] DOLOMITE. 193 chello, from Bleiberg in Carinthia, exhibits beautiful irides- cent colours from fossil shells, sometimes deep-red or orange {Fire marble). Limestone occurs in all formations under various names, as Oolite, egg or roe-stone, round concretions, with a con- centric structure like the roe of fish ; Pisolite, or peastone, similar structure; Chalk, soft earthy: Lithographic stone, yellowish and compact, from Solenhofen ; and Marl, cal- careous matter more or less mixed with clay. Tufa, or calcareous tufa, generally a recent deposit from calcareous springs, has often a loose friable texture, but at other times is hard and compact ; and in the neighbourhood of Eome forms the common building-stone or Travertino. The sand- stone of Fontainebleau is carbonate of lime (|) mixed with quartz sand (f ), and occasionally crystallising in rhonibo- hedrons. This mineral is employed in many ways — the coarser varieties when burnt to drive off the carbonic acid, as lime, for mortar, manure, tanning ; as a flux in melting iron and other ores, or in preparing glass, and for similar purposes; the finer, as marbles, for sculpture, architecture, and orna- mental stonework; the chalk for writing, whitewashing, or producing carbonic acid. Plumhocalcite.—ClemsigQ, 1 04° 53^ White and pearly; softer than calc-spar ; but G. - 2-824. Contains 2-3 to 7-8 carbonate of lead. Wanlockhead and Leadhills, Scot- land. ""^16. Dolomite, Bitter fCa C -f Mg C. = Spar. 1 [Ca 0 . CO' -f Mg 0 . CO']. Hexagonal-rhombohedral ; E 106° 15—20'; most fre- quent form E ; also E and -^E, or OE, ooE, and 4E. Ihe rhombohedrons often curved and saddle-shaped; also granular or compact, often cellular and porous. Cleavage, rhombohedral along E. H. - 3-5...4-5 ; G. - 2-85. ..2-95. Translucent ; vitreous, but often pearly or resinous. Co- lourless or white, but frequently pale-red, yellow, or green. B.B. mfusible, but becomes caustic, and often shows traces of iron and manganese. Fragments effervesce very slightly or not at all in hydrochloric acid ; the powder is partially 194: BEErXNEEITE. [C'-jlc-s-fjar soluble, or Avliolly ,^-lieu heated : the very fine powder ignited on platina-fL'dl for a few minutes over a spiritdamp iyvu'yiuus pidverulent. hut intumesces slightly during igni- tion. Chem. com. 5 4 '3 carbonate of lime, and 45 '7 car- bonate of magnesia (30 lime and 22 magnesia), but gene- rallv carbonate of lime with more than 20 per cent carbonate of magnesia, and less than 20 per cent carbonate of iix»n. Varieties are — Lo^'yiu't^':. massive, granular, easily divi- sible, white : Bhomh or Ei'^Lr-sj'ur. larger grained, or dis- tinctlv crvstallised and cleavable, often inclining to green ; and iy:i::i-y:":'r and Fearl-Sj:":'/'. in simple crystals or ui imi- tative forms, of colours inclining to red or brown, more dis- tinct pearly lustre, and under 10 per cent carbonate of iron. Traversella in Piedmont. St. Gotthardt. Gap in France. Alston in Cumberland, in Derbyshke. and at Lead- hills and Charlestown in Scotland. Greenish, macled ; Miemo in Tuscany OliunaA and Tharand in Saxony (Tha- randit'j). G''j.r}i:'V.an. from Gurhof in Austria, is white and compact. The massive and compact varieties are very common, and valued as building-stones (cathecbal of ^lilan, York Minster, and the new houses of Parliament). The Parian marble, and also the Ljna marble in the Hebrides, have been supposed to Ijelong to this species. Freda^zi'^:. — Granular and white ; is a mixture with brncite. Predazzo in Tyi^ol. 176. Beeuxneeite. Ginbertite.— Mg C = [Mg 0 . CO']. Hex.-rhombohedral : E 107' 10— 30' : as yet only E ; and granidar or columnar. Cleavage. E very perfect, with straight faces. H. ^..A'o ; G. = 2-9. ..3T. Transparent or translucent on the edges ; highly vdtreous. Colourless, but often yellowish-brown, or blackish-gray. B.B. infusible, but generally becoming gray, or black and magnetic ; so- luble in acids, often only when pulverised and warmed. Chem. com. essentially carbonate of magnesia, ^\\\.\\ .3T7 carbonic acid and 48 "3 magnesia, but often mixed with 8 to 17 carbonate of iron or manganese. Tyrol, St. Got- thardt, Harz, Fassathal ; also Unst in Zetland. Famihj.] MAGNESITE — AEEAGONITE. 195 Mesitine-spar, splendent, yellow, lenticular crystals ; G. = 3 '35... 3 "4; Traversella in Piedmont; and Fistomasite ; G. = 4*4 j Salzburg ; are similar. 177. Magnesite. — Mg 0. Eeniform or massive. H. = 3...5; G. = 2'85...2'95. Sub-translucent or opaque ; streak shining. Snow-white, grayish, or yellowish-white, and pale-yellow. Adheres slightly to the tongue. B.B. and with acids acts like breun- nerite, of which it is only a chemical pure and compact variety. Tyrol, Norway, ^vTorth America. 178. Hydromagnesite. — Mg* C^ + 4 H. Monoclinic ; ooP 88° nearly. Crystals small, rare ; also massive. H. = 1'5...3; G. = 2'14...2'18. Vitreous silky. White. B.B. infusible ; soluble with efferves- Chem. com. 36*2 carbonic acid, 44 mag- water. Moravia, Kumi, Hoboken in New Jersey, and Texas in Pennsylvania. Lancasterite from Pennsylvania, and Hydromagnocalcite, a yellow sinter from Vesuvius, are similar. *-^179. Arragonite, Needle Spar, Flos-ferri.- — Ca C. Ehombic; (xP 116° lO*; Poo 108° 27'. The most com^mon combinations are ooPoo (A), coP (M) .Poo (k, F), generally long prismatic (like Fig. 165, and the separate or cence in acids, nesia, and 19'( 1 — h M M M Fig. 165. Fig. 166. Fig. ler. crystals in Fig. 166); coPoo. coP. OP, generally short prismatic ; 6P|- . oo P . Poo , acute pyramidal. But simple 196 FLUOEITE. [Fluor-spar crystals are rare, from the great tendency to form macles, conjoined by a face of ooP, and repeated (Figs. 166, 167). Also columnar, fibrous, and in crusts, stalactites, and other forms. Cleavage, brachy diagonal distinct, also ooP and Poo imperfect; fracture conchoidal or uneven. H. = 3-5 ...4; G. = 2-9.. .3 (massive 2-7). Transparent or translucent j vitreous. Colourless, but yellowish-white to wine-yellow, reddish-white to brick-red ; also light-green, violet-blue, or gray. In the closed tube, before reaching a red heat, it swells and falls down into a white coarse powder, evolving a little water. A portion of this powder heated in the forceps, B.B., colours the flame carmine-red when^ strontia is present ; on charcoal it becomes caustic. With acids acts like calc-spar. Chem. com. carbonate of lime, occa- sionally mixed with (01... 4) carbonate of strontia. Va- lencia, Molina, and in Arragon ; Leogang in Salzburg, and Antiparos. Flos-ferri, coralloid, in the iron mines of Styria. Satin-spar, fine fibrous silky, at Dufton; stalactitic in Buck- inghamshire, Devonshire, coast of Galloway, and Leadhills ; also deposited as tufa by the Carlsbad and other hot springs. Arragonite is most readily distinguished from calc-spar by falling to pieces at a low temperature, and by its less distinct and prismatic cleavage. Tarnowitzite contains 2 to 4 carbonate of lead. Tarno- witz in Silesia. **Famtly II. — Fluor-Spar. Crystallisation tesseral, hexagonal, or rhombic. H. 4 ...5, in one 7; G. = 2'9...4-7, but mostly about 3. All soluble in acids, and mostly fusible or altered by heat. Those containing fluorine, Avhen warmed with concentrated sulphuric acid, evolve vapours that corrode glass; those with phosphoric acid, when moistened with sulphuric acid, colour B.B. the flame green. **180. Fluorite, Fluor-spar. — Ca F, or [Ca F^]. Tesseral; the most common form is the cube ooOoo , then the octahedron 0, and the rlioml)ic do(h^.cahedron ooO ; but many other forms occur in combinations. Macles are Family.'] yttrocerite — fluocerite. 197 common ; also coarse granular, columnar, or compact and earthy. Cleavage, octahedral perfect j fracture conchoidal j brittle. H. = 4 ; G. = 3 '1 ... 3 '2. Pellucid in all degrees ; vitreous. Colourless, but generally very various, and beau- tiful shades of yellow, green, blue, and red ; often two or more in one specimen. Many varieties phosphoresce when heated {Chlorophane, with a bright green light). B.B. de- crepitates, often violently, phosphoresces and fuses in thin splinters to an opaque mass ] slowly soluble in h. or nitric acids, readily in s. acid, with evolution of hydrofluoric acid. Chem. com. neutral fluoride of calcium, containing 48*7 fluorine, and 51-3 calcium ( = 72 lime). Fluor-spar is a very common mineral, chiefly in veins, as with tin ores in Saxony, Bohemia, Cornwall; with silver at Freiberg, Marienberg, Kongsberg ; with lead in Derbyshire (near Castletown), Cumberland (Alston Moor), Northumberland, and Ireland. It is rare in Scotland, but in greenstone near Gourock, in granite near Ballater in Aberdeenshire, on the Avon in Banffshire, and in Sutherlandshire. In Derby- shire it occurs in large crystalline masses either with con- centric colours or of a rich translucent blue {Blue John), and is wrought into various ornamental articles. Fluor- spar is chiefly used as a flux in reducing metallic ores, especially iron and copper ; also for etching on glass. 181. Yttrocerite. Very similar to fluor-spar. Granular, crystalline, or in crusts. Cleavage imperfect. H. = 4...5 ; G. = 3-4... 3-5. Translucent or opaque ; weak vitreous lustre. Violet-blue to gray or white. B.B. infusible on charcoal alone, and evolves fluorine when heated with s. acid. Chem. com. fluorides of calcium, cerium, and yttrium, in variable pro- portions. Finbo and Broddbo near Fahlun, Massachusetts, and Amity in New York. 182. FLUOCERiTE.-^Ce F -f Ce' F = [Ce F' -f Ce' F']. Hexagonal; OP . ooR H. = 4...5 ; G. = 4'7. Opaque or translucent on the edges ; lustre weak. Pale brick-red or yellowish ; streak yellowish-white. In the closed tube gives out fluorine. B.B. infusible. Chem. com. 82-64 198 FLUOCEEINE— CRYOLITE— CHIOLITE. [Fluor-spar peroxide of cerium, 1-12 yttria, and 16-24 hydrofluoric acid, Berzelius. Finbo and Broddbo. 183. Flxjocerine. — Ce^T + QB.. , -j i Massive, with traces of cleavage 3 fracture conchoidal. H =4-5. Opaque; vitreous or resinous. Yellow, incUn- inc. to red or brown ; streak brownish-yellow. B K antu- sible. Analysis, 84-21 peroxide of cerium, 10-85 hydro- fluoric acid, and 4-95 water. Finbo. Bastnestte, from Bast- naes, 2 (La, Ca) C + Ce F, with 20-2 carbonic acid, 46-2 lanthanium oxide, 3-8 cerium protoxide, 21-1 cerium, and 8*7 fluorine, is similar. ^ . -, -t^st 184 CRY0LITE.-3 Na F -f F, or [3 Na F -f- Al P]. Triclinic, but crystals very small, and resemble a com- bination of the cube and octahedron. Mostly mdistmct crystalline or granular. Cleavage, one perfect, two others less so, the three nearly at right angles ; brittle. H. - 3 ■ G = 2-9 3 Translucent, and after immersion m wlter almost transparent; vitreous, but on OP rather pearly Colourless and snow-white, but often grayish, yellowish, or reddish. B.B. fuses very easily (even m the flame of a candle) to a white enamel; in open tube shows traces of fluorine ; partially soluble in h. acid ; wholly so in s., with evolution of fluorine. Chem. com. 54 A^ionne 1 3 aluminium, and 33 sodium. Ivigtok, Arksutfiord, m South Greenland, Miask in Ural. Used for preparations of soda and alumina, and as an ore of aluminium. Fachnolite, small rhombic prisms in druses of cryolite, has nearly half the sodium replaced by calcium and 9 water. I 3 Na F + 2 Al- F' = A. 185. Chiolite.— I 2 j;^,^ ^ F' = B. Tetragonal, inminute pyramids, withmiddleedge 1 1 r 44'; ocP 124° 22'; mostly granular. Cleavage, P rather perfect. H=4 Eesinous. White. Very easily fusible (more so than cryolite), colouring the flame deep yellow ; evolves fluoric acid. Chcm. com. twofold; one variety (A) with G = 2-8 2-9, containhig 1 8 0 aluminium, 23 4 sodium, and 58 fluori;; ; the second (15), with U. = 3^0...3-l, containing 16-4 aluminium, 27-8 sodium, and 55-8 fluorine Miask 111 Siberia B has been named NIpholite; and a similar Family.'] HOPEITE — APATITE. 199 mineral, but with calcium, 7 per cent, for part of the sodium, Arhsutite, occurs with the cryolite. Fluellite. — Small, white, transparent, rhombic pyramids ; polar edges 109° 6' and 82° middle 144°. Consists essentially of fluorine and aluminium. Stenna-gwyn in Cornwall. Frosoj)ite. — Crystals like datholite. H. = 4-5. Vitreous. Colourless and transparent. Scheerer found 42 alumina, 32 fluoride of calcium, 11 fluoride of siHcium, and 15 water. Altenberg ; Schlackenwald (T). 186. HOPEITE. Ehombic; oof 2, 82° 20'; P with polar edges 106° 36' and 140°. Cleavage, macrodiagonal perfect. H. = 2 "5 . . . 3 ; Gr. = 2*76. ..2-85. Vitreous or pearly. Grayish-white. B.B. melts to a clear globule, tinging the flame green ; soluble in acids without eff'ervescence. Chem. com. oxide of zinc and cadmium, with phosphoric (or boracic'?) acid, and much water. Eare. Altenberg near Aix la Chapelle. I 3 Ca^ P + Ca(Cl, F), or nS7. Apatite.-^ ^3 ^3 q ^ _^ Cap^ F^)]. Hexagonal and pyramidal-hemihedric ; P 80° 26'; the Fig. 168. Pig- 169. most common forms are ooP (ilf), ^P2 (e), OP (P), P (x); the basis OP seldom wanting. The crystals (Figs. 168, 169) are short prismatic or thick tabular, and often striated vertically. Also granular, fibrous, or compact. Cleavage, prismatic and basal both imperfect ; fracture conchoidal or uneven and splintery; brittle. H. = 5 ; G. = 3*1... 3*2 5 200 HERDEEITE — CHILDEEXITE. [Fluor-sjxf.r Transparent to opaque : vitreous, but resinous on the cleav- age-planes and fracture. Colourless and white, but gener- alh' light green, gray, blue, violet, or red. In powder phosphoresces with heat. B.B. fusible in thin splinters with much difficulty to a colourless, translucent glass \ mois- tened with sulphuric acid it colours the flame green ; soluble in nitric or h. acid. Chem. com. phosphate of lime (89 to 9'2"o), with chloride (to 11) or fluoride (to 7*7) of calcium, or both. Disseminated in gTanite, gneiss, mica, and horn- blende slates, and trap rocks. Also in beds and veins. In tin mines in Saxony, Bohemia, St. Michael's Mount, St. Agnes, and Botallack in Cornwall ; in granite, Bovey Tracey in Devonshire, Caldbeck Fell in Cumberland, near Cromarty, and in Aberdeenshire : also at St. Gotthardt, the Tyrol, and Krageroe, Hammond and Eden^dlle in Xew York, and Elmsley, Canada. Moroxife, opac^ue greenish-blue from Arendal. AsjKiragus-stone, translucent, wine-yellow crystals, from the Zilleithal in T}to1. Fhosjjhorite, massive, from LogTosan in Estremadura. Jlagnesia-avafite, fi^om Kussinsk in the Ural, contains 7 '7-1 magnesia. 188. Herdepjte, Allogonite.— Ai, Ca, P, F. PJiombic ; P polar edges 77^ 20' and 14P 16', ocP 115'' 53'. Cleavage, c/:Px and ccP imperfect: fracture conchoidaL H. = 5 ; Ct. = 2-9...3'0. Translucent; vitreous, inclinmg to resinous. Yello^vish or greenish white. B.B. difficultly fusible to a white enamel : moistened with s. acid colours the flame green ; soluble in warm h. acid. Ehren- friedersdorf in Saxony, but extremely rare. 189. Childrexite.— 2 (Fe, Mn)' P + Al- P + 15 H. Rhombic; polar edges 101' 43', 130° 10', middle 98° usual form P . 2Px . xPx (^',(7, P, Fig. 170). Cleavage, P imperfect. H. = 4"5...5. (t. = 3 • 1 8 . . . 3 '3. Translucent ; vitreous. Yel- lowish-white to wine or ochre yellow, brown, or almost black. B.B. infusible, but swells up ^' ' ' and colours the flame bluisli-green ; slowly soluble in wai^ni h. acid. Chen], com. 30*7 ii'ou protox- Family.'] XENOTIME — BOEACITE. 201 ide, 9 manganese protoxide, 14*5 alumina, 29 phosphoric acid, and 17 water. Tavistock in Devonshire, Crinnis in Cornwall, and Callington in Cumberland. 190. Xenotime.— Y' P. Tetragonal j P 82°. Crystals P . ooP. Cleavage, ooP. H. = 4*5 ; G. = 4'4...4'55. Translucent in thin splinters ; resinous. Yellowish or reddish-brown, and flesh-red ; streak paler. B.B. infusible. Chem. com. 62 yttria, and 38 phosphoric acid, but some with 8 to 11 cerium prot- oxide. Lindesnaes and Hitteroe in Norway, Ytterby, Sweden, and Georgia, U.S., and (JFiserin) St. Gotthard. 191. BORACITE.- f 2 Mg" + Mg CI, or t [2 (3 Mg 0 . 4 0') + Mg C?]. Tesseral, and liemihedral; ooOoo , coO (Fig. 171), and— * 2 Cleavage, octahedral very imperfect ; fracture conchoidal j brittle. H. = 7 ; G. = 2 -9 . . . 3. Trans- parent, or translucent on the edges. Vitreous or adamantine. Colourless or white, often grayish, yellowish, or greenish. Becomes polar electric by heat. B.B. fuses with difficulty to a clear yellowish bead, which on cooling forms a white opaque mass of needle- like crystals ; at same time colours the flame green ; soluble in h. acid. Chem. com. 62*5 boracic acid, 26*9 magnesia, 7*9 chlorine, and 2*7 magnesium. Liineberg and Segeberg in Holstein ; Stass- furt. Stassfurtite. — In very minute prismatic crystals. White. Chem. com. same as boracite, and thus perhaps dimorphous. Stassfurt in Germany. Rhodizite agrees in most characters with boracite ; only H. = 8 and G. = 3-3. ..3-42. B.B. fuses difficultly on the edges, colouring the flame first green, then green above and red below, and at last in some varieties all red. Chem. com. borate of lime. Mursinsk in Siberia. Fig. 171. 202 HYDEOBOKACITE-DATHOLITE. [Heavy Spar Hydkoborocalcite.— Ca B' + 6 H. Delicate sno.-^vhite crystals, .-ith 19 lime, 46 boraac acid, and 35 .rater. Iqiuque m Peru. 193. HYDROBORACiTE.-Ca^ + Mg B + 12 H. Radiating and foHated like gyp-m.^ ^ - -1^^^ ...2. Translucent. White, but partly ■ ^.^^^ easily, tinging the flame green ; easily soluble m y arm acids. Cheni. boracic acid, and 26-33 49-58 1^ a s com. 13-52 lime, 10-57 magnesia, _ boracic acici, and 26-33 .vater. Caucasus. A similar Sal with soda in place of magnesia is found m Peru. n94. DATHOLITE, Borate! CaB + Ca Si- + H, or of Lime. j [CaB Si H O J. V • p -^()° 51' xP (/•) 76° 38', xP°2 (f/) Mo^^clin^c;a-^^^^ ocP. (.^, P. (0) 7fI-. n2 : 0^ rhombic 4ilh ^ : / 90°, & : « 135- 1^141° 9'° and 160° 39'; also coarse graniilar. Cle vi -e, orthodiag/na/ and .P very imperfect ; fracture uneven or conclioidal. ti.-o... 5 -5 ; a = 2 -9 ... 3. Transparent or translucent ; vitreous ; on the frac- ture resinous. Colourless or white, inclining to gray, green, yellmy, and red. In closed tube )^elds water B.B. intumesces, and melts clear glass, colouring the Aame green ; the ' • ^ Chem. com. 38-1 silica, 21 6 iim^ 5-6 water. Arendal, Utoe, Hill, Glen Farg in Perthshire, and near Dunnotai , Con ''''tl-;:!iS^^rons, botryoidal or reniform, sik>^ white or hair-bvo.vn ; otherwise, and in chem. com., like datholite, but with two atoms water. Arendal. Family III.— Hea\'Y Spar. Crystallisation rhomlnc specially^ H. = 3 ..4-5 ; a = 3-2. ..4-7, but mostly 3-G...4-5. Transparent oi trans easily to a powd, ^ boracic acid, 34-7 lime. easily lo a uicai ^^c.^^, powder gelatinises in h. acid. . , « . ^ and Family.] BAEYTES. 203 H.-3...3-5; lucent ; colourless or coloured red, yellow, blue, or green. Soluble in acids, except barytes and celestine. B.B. fusible or decompose. Those containing baryta colour the flame yellowish-green ; those with strontia carmine-red, best seen when moistened with h. acid. The sulphates fused with soda and then moistened leave a black stain on silver. =^^195. Barytes, Heavy Spar.— Ba S. = [Ba 0 .^SO']. Ehombic Pooj^) 78° 20; (/) 105° 22^ co P2 (d) 77° also ooPod (c) (Figs. 173, 174, a different position, d d being placed vertical). The crystals show very many forms and combinations, and are tabular or columnar, often in druses or groups ; also foliated, fi- brous, granular, or compact. Cleavage, brachydiagonal per- fect, along Poo less perfect; basal traces. G. = 4-3 ... 4-7 (4-48). ^ 2 Transparent to translu- cent ; vitreous or resinous. Colourless and white, but generally reddish-white, or flesh-red, yellow, gray, bluish, greenish, or brown, decrepitates violently, and fuses very difficultly, or only on the edges, colouring the flame yellowish-green ; not soluble in acids. Chem. com. 34*3 sulphuric acid, and 65-7 baryta, but occasionally with 1 to 15 sulphate of strontia. Very common, chiefly in veins, either alone or accompanying ores. Crystals at Dufton, Bohemia, Felsobanya and Kremnitz in Hungary, Auvergne, and United States. Columnar at Freiberg. The radiated from near Bolog.^ or the Bolognese stone, phosphoresces in the dark. Massive or Cawh from Derbyshire and Staffordshire ; in Scotland at Leadhills, Braid Hills near Edinburgh, the Fig. 174. B.B. Fig. 175. 204 DKEELITE — WITHERITE — ALSTONITE. [Heavy Spar Pentlands and Cheviots, and Arran, where mined as a white pigment. Lime Barytes, from Freiberg, Strontian, and Derbyshire, seems a mixture with sulphate of lime ; crystals, tabular, in rosettes and other groups. G. = 4'0...4-3. Hepatite. — Dark-gray, from carbonaceous matter ; Kongsberg. AUomorpJiite, scaly, white and pearly, near Eudolstadt, agrees essentially with barytes. 196. Dreelite.— Ca S + 3 Ba S.' Ehombohedral ; E 93°. Cleavage, E imperfect. H. = 3. ..4; G. = 3'2...3'4. Lustre dull; on cleavage pearly. White. B.B. fuses to a white vesicular glass ; effervesces with h. acid, but only partially dissolves. Chem. com. 61*73 sulphate of baryta, 14*27 sulphate of lime, 8*05 car- bonate of lime, 9*71 silica, 2*40 alumina, 1*52 lime, 2*31 water. Nuissiere near Beaujeu. *197. WiTHERiTE.— Ba C, or [Ba 0 . CO']. Ehombic; ooP (if) 118° 30', 2 Poo (P) 112° (Fig. 176). Crystals not common, and often have quite a hexagonal aspect ; macles like arragonite. More common spherical, botryoidal, or reniform, with radiated columnar texture. Cleavage, coP distinct, 2 Poo and ooPoo imperfect; frac- ture uneven. H. = 3...3*5; G. = 4*2. ..4*3. Semi- transparent or translucent; vitreous, or resinous on the fracture. Colourless, but generally yellow- ish or grayish. B.B. fuses easily to a transpa- rent globule, opaque when cold; on charcoal boils, becomes caustic and sinks into the support; soluble with effervescence in nitric or h. acid. Chem. com. 22*3 carbonic acid and 77*7 baryta. Alston Moor and Hexham in Northumberland; also in Styria, Salz- burg, Hungary, Sicily, Siberia, and Chili. 198. Alstonite.— Ba C + Ca C. Ehombic, like witherite ; ^ooP 118° 50', 2 Poo llT 50' ; usual combination P . 2 Poo . (xP, resembling a hexa- gonal pyramid. Cleavage, ooP and ooPoo rather distinct. H. = 4. ..4*5 ; G. = 3*65... 3*76. Translucent ; weak resinous. Family. ] B ARYTO-C ALCITE — CELESTINE. 205 Colourless or grayish-white. Chem. com. 66 carbonate of baryta and 34 carbonate of lime, thus identical with the baryto-calcite. Fallowfield near Hexham, and Alston Moor. 199. Baryto-Calcite.— Ba C + Ca C. Monoclinic j 0.^69° 30'; ooP (h) 84° 52^ P (m) 106° 54; 61° (Fig. 177); also columnar and granular. Cleavage, P perfect, P^oo less per- fect. H.=4; a = 3-6. ..3-7. Transparent or translucent; vitreous, inclining to resinous. Yel- lowish-white. B.B. infusible, but becomes opaque y and caustic. Chem. com. like alstonite, Alston I y Moor. ^^^^ Eig. 177. *200. Celestine.— Sr S - [Sr 0 . S 0']. Ehombic; forms like barytes and anglesite; Poo 104°8', Pgo (ilf) 75° 58'. Usual combinations Poo .Poo . ooPoo , or this with GoP2 {dY(Fig. 179, also 178, but in another posi- tion) ; also columnar and foliated ; or fibrous, fine granular or compact. Cleavage, macrodiagonal perfect; along Poo less perfect. H. = 3...3-5; G. = 3-9...4. Transparent or trans- lucent ; vitreous or resinous. Colourless, but usually bluish- white to indigo-blue, and rarely reddish or yellowish. B.B. decrepitates and fuses easily to a milk-white glo- bule ; colours the flame carmine-red. Distin- guished from barytes by a splinter after ignition in the inner flame, being moistened with h. acid, and held in the blue border of the flame of a candle, colouring this of a lively purple-red. Scarcely afl"ected by acids. Chem. com. 43*6 sulphuric acid, and 5 6 '4 strontia, but often some baryta or lime. Sulphur mines of Girgenti and other parts of Sicily, Herrengrund in Hungary, Bex, Salzburg, Monte Viale near Verona, and Meudon and Montmartre near Paris ; in England near Bristol, and Knaresborough ; in Scotland at Inverness, Tantallon Castle, Calton Hill. Used for strontium preparations, and red-light in fireworks. Baryto-celestine. — Eadiating columnar or foliated. Bluish- white ; very brittle and friable. H. = 2-5 ; G. = 3-92. B.B. 206 STRONTIANITE — GYPSUM. [Gypsum difficultly fusible. Chem. com. 2 Sr S + Ba S, with 36 strontia, and 23 baryta. Diamond Island in Lake Erie, Kingstown in Upper Canada, and Binnenthal. *201. Strontianitk— Sr^C = [Sr 0 . CO']. Khombic ; ooP 117° 19; Poo 108° 12' . Crystals (Fig. 180) and macles like arragonite ; also broad columnar and fibrous. Cleavage, prismatic along ooP (ilf) and 2 Poo (P) (69° 160 imperfect. H. - 3-5 ; G. = 3'6...3-8. Translu- cent or transparent ; vitreous or resinous on fracture. Co- lourless, but often light asparagus or apple-green, more rarely -____^-.,_ -r~^ grayish or yellowish. B.B. fuses 7''' r \^-^ ~^\ in a strong heat only on very ^\ — ^s.^/^ thin edges ; intumesces in cauli- Mi flower-like forms, shines brightly, --y—J: — -~/y^ and colours the flame red ; easily r- ^..jlI-J^ soluble with effervescence in acids. Fig. 180. Paper moistened with the solution in h. acid burns with a carmine-red flame. Chem. com. 30 carbonic acid and 70 strontia, but often contains carbonate of lime (6 to 8). Leogang in Salzburg, Braunsdorf in Saxony, Hamm in Westphaha, the Harz ; at Schoharie and other parts of the United States (Emmonite) ; Strontian in Ar- gyleshire, Leadhills, Yorkshire, and Giant's Causeway. It is used to produce red fire in pyrotechnic exhibitions. Stromnite or Barystrontianite. — Yellowish- white, semi- translucent, faint pearly lustre. H. = 3'5 ; G. = 3*7. Con- tains 68-6 carbonate of strontia, 27-5 sulphate of baryta, and 2-6 carbonate of lime. Stromness in Orkney. Family IV. — Gypsum. Crystallisation rhombic or monoclinic. H. = 2...3, or less, many yield to the nail. G. 2-2... 2-9, or also low. All, except the sulphates, soluble in acids, some in Avater ; also fusible in general. Mostly translucent and colourless, but often coloured by mixtures. **202. YPSUM.— Ca S + 2 H, or [Ca 0 . SO"'' + 2lV 0]. Monoclinic ; C. = 80° 57' ; the most common forms Family.'] GYPSUM — ANHYDRITE. 207 are ooP llT 30^ P 138° 40', -P 143° 30^ and ooFoo . Two common combinations are ccP (/) . cxP'^oo (P) . — P (l) (Fig. 181), and this with P. Lenticular crystals often occur ; macles frequent (Fig. 83 above); also granular, compact, fibrous, scaly, or pulverulent. Cleavage, clinodia- gonal very perfect, along P much less per- fect ; sectile, thin plates flexible. H. = 1'5 ...2 (lowest onP); G. = 2-2. ..2-4. Trans- parent or translucent ; vitreous, on cleavage pearly or silky. Colourless and snow-white, but often red, gray, yellow, brown, and more rarely greenish or bluish. In the closed tube yields water. B.B. becomes opaque and white ; exfoliates and fuses to a white enamel, which is alkaline ; soluble in 400 to 500 parts of water, scarcely more so in acids. Chem. com. 46 '5 sulphuric acid, 32*6 lime, and 20*9 water. Gypsum is a very common mineral, often in nests or reniform masses in clay or marl. Transparent crystals, or Selenite, occur in the salt mines of Bex in Switzerland, of the Tyrol, Salzburg, and Bohemia, in the sulphur mines of Sicily, at Lockport in New York, in the clay of Shotover Hill near Oxford, at Chatley near Bath, and many other localities. Fibrous gypsum at Ilfeld in the Harz, and Mat- lock in Derbyshire. Compact gypsum at Volterra in Tus- cany (Alabaster), and in whole beds in many parts of Ger- many, France, Italy, and England, often with rock-salt. The finer varieties, or Alabaster, are cut into various ornamental articles. Plaster of Paris, used for casts and other works of art, is formed by calcining gypsum at a temperature below 300° Fahr., and grinding it down to a fine powder, which forms a paste that soon hardens by absorbing the water driven off" by the heat. *203. Anhydrite, Karstenite.— Ca S = [Ca . 0 . S 0']. Ehombic ; (xP 90° 4^ P^ 96° 30'. Crystals OP. ooPoo . ooPgo . ooP, but rare ; chiefly granular, or almost compact or columnar. Macles rare. Cleavage, macrodiagonal and 208 POLYHALITE- : — GLAUBEEITE. [Gypsum bracliydiagonal both very perfect, basal perfect. H. = 3... 3-5 j G. = 2-8...3'0. Transparent or translucent ; vitreous ; on CO Poo pearly. Colourless or white, but often blue, red, or gray; streak grayish-white. In closed tube gives no water. B.B. fuses difficultly to a white enamel ; with fluor spar fuses readily to a clear globule, which becomes opaque when cold, and, on continuation of the heat, intumesces and becomes infusible ] very slightly soluble in water or acids. Chem. com. 58-75 sulphuric acid and 41-25 lime. The crystalline, or Miiriacite, occurs in the salt mines of Bex, Hall in Tyrol, and Aussee in Styria ; also Sulz, Stass- furt, and Bleiberg. Compact at Ischel in Austria, Berch- tesgaden, Eisleben, and the Harz. Granular, or Fuljmute, near Bergamo. The contorted, or Gekrosstein, chiefly at Wieliczka and Bochnia. 204. POLYHALITE.— 2 Ca S + iMg S + K S + 2 H. Ehombic; ooP 115°; mostly columnar or fibrous. Cleavage, a:P imperfect. H. = 3-5 ; G. = 2'7...2-8. Trans- lucent ; pearly or resinous. Colourless, but generally pale red, seldom gray. Weak bitter, and slightly saline taste. Soluble in water, leaving gypsum. B.B. fuses on charcoal to an opaque reddish bead, becoming white when cold. Chem. com. sulphate of lime 45, of magnesia 20-5, of potassa 29, and water 5-5. Ischel, Aussee, and Berchtesgaden. 205. Glauberite, Brongniartin. — Xa S + Ca S. Monoclinic; G = 68° 16'; o^P 83° 20^ — P 116° 20'. Crystals OP.— P, or with cr.P (P, /, 21, Fig. 182).^ Cleavage, basal perfect, along ocP traces. H. = 2-5...3; G. = 2-75... 2-85. Translucent; vitreous to resinous. Colourless, but yellowish or grayish white, yellow, or red. Taste slightly saline and bit- ter. B.B. decrepitates violently, and melts to a clear glass ; decomposed by water, which removes the sulphate of soda. Chem. com. 51 sulphate of soda, and 49 sulphate of lime. Villarubia in Spain, Vic, Berchtesgaden ; near Brugg in Aargau, Aussee and Ischel in Austria, and Tarapaca in Peru, with 1 to 5 boracic acid. Family. ] ALUNITE— ALUMINITE — PHARMACOLITE. 209 206. Alunite,] 3 ±\ S + K S + 6 H, or Alumstone. I [K'O . SO' + 3 (AF 0' . SO^) + 6 0]. Ehombohedral ; R 89° 10^ Crystals, E, or E . OE (Fig. 183); also fine granular, earthy, or compact. Cleavage, basal rather perfect. H. = 3*5 ...4 j G. = 2-6...2-8. Translu- cent ; vitreous, on OE pearly. Colourless and white, but gray- ish, yellowish, or reddish. B.B. decrepitates; infusible alone; but Fig. iss. becomes blue with cobalt solution. Soluble in warm con. s. acid, not in h. acid. Chem. com. 37*2 alumina, 11*3 potash, 38 -5 sulphuric acid, and 13 water. Bereghszasz * in Hungary, Tolfa, Lipari Islands, Auvergne, and Milo. , Jarosite; dark yellow or brown, is isomorphous, and chem. com. similar, but Fe for Al. Spain, Saxony, and Mexico. 207. Aluminite, Websterite.— A1 "S + 9 H. Eeniform, and very fine scaly or fibrous. Fracture earthy; sectile or friable. H. = 1 ; G. = 1*7. Opaque; dull or glimmering ; snow-white or yellowish-white. In closed tube yields much water. B.B. emits sulphurous fumes, the remainder being infusible ; easily soluble in h. acid. Chem. com. 29*8 alumina, 23*2 sulphuric acid, and 47 water. Newhaven in Sussex ; Eperney, Auteuil, and Lunel Vieil in France ; Halle and Mori in Prussia. Felsd- hanyite from Hungary, in rhombic tables, is similar. 208. Phakmacolite.-{ g^^^^ + \fj^ ^ Monoclinic; C. = 65° 4'; ooP 117° 24^ - P 139° 17^ Crystals prismatic ; often acicular or capillary, or radiated fibrous crusts. Cleavage, clinodiagonal very perfect ; sec- tile and flexible. H. = 2...2-5; G. = 2'6...2-8. Trans- lucent ; vitreous ; pearly or silky. Colourless and white, but red or green. Yields water in the closed tube. B.B. fuses to a white enamel ; in the inner flame on charcoal gives arsenic fumes, and fuses to a semitranslucent grain, colouring the flame blue ; easily soluble in acids. Chem. P 210 HAIDINGERITE — BERZELIITE — STRUVITE. [EocJc-salt com. 51 arsenic acid, 25 lime, and 24 water. Andreasberg, Eiechelsdorf, Biber, Joachimstlial, Markirchen, and Wittichen. Picropharmacolite contains magnesia. Boselite, vitreous ; rose-red. B.B. with borax forms a deep-blue glass. ^ Chem. com. arsenic acid, oxide of cobalt, lime, magnesia, and water. Schneeberg in Saxony. 209. Haidingerite. — Ca^As + 3 H. Ehombic; ocP 100°. Cleavage very perfect; sectile, flexible. H. = 2...2-5; G. = 2-8. ..2-9. Otherwise like pharmacolite. Chem. com. 85*68 arseniate of lime and 14*32 water. Joachimsthal. 210. Berzeliite. — Ca'As + Mg'As. Massive, with traces of cleavage. Brittle. H. = 5.5 ; G. =:2-52. Translucent on the edges; resinous. Honey- yellow or yellowish-white. B.B. infusible, but becomes gray ; soluble in nitric acid. Contains also 2 to 4 man- ganese protoxide. Longbanshytta in Sweden. 211. Struvite, Guanite.---(NH' 0, Mg ) P + 12 H. Ehombic; Poo 63° 7\ Poo 95°. Cleavage, brachy- diagonal perfect. H. - 1-5... 2 ; G. - 1-66. ..1-75. Trans- parent or opaque; vitreous. Colourless, but yellow or brown. In the closed tube yields water and ammonia. B.B. fuses to a white enamel; -soluble in h. acid, and very slightly in water. Chem. com. 29*9 phosphoric acid, 16-3 magnesia, 10-6 ammonia, and 44 water. Under St. Mcolai church at Hamburg, and in guano from Africa. ^Family V. — Eock-Salt. Crystallisation monoclinic and rhombic, some tesseral or hexagonal. H. = 1...3, but most about 2; G. = 1*5... 3, but generally 2. All soluble in water, and B.B. fusible or decompose. When pure, mostly colourless, white, trans- lucent, and vitreous. They are chiefly products of decom- position, and occur especially in the rainless regions, or in lakes not communicating with the sea. Occasionally form beds or masses in the strata. Many are valuable in the arts, or used as medicine, and then produced artificially. **212. Eock-Salt.— Na CI. Tesseral ; almost always cubes. Generally granular and Family.] EOCK-SALT — CAENALLITE. 211 fibrous. Cleavage, hexahedral very perfect ; fracture con- choidal ; rather brittle ; yields slightly when scratched with the nail. H. = 2 ; G. = 2 1,,.2'2. Transparent or trans- lucent ; vitreous. Colourless or white, but often coloured red, yellow, gray, and rarely blue. Taste saline. In the closed tube decrepitates, and yields a little water. B.B. on charcoal fuses and partly evaporates, partly sinks into the support. With soda fuses to a clear mass, colouring the flame yellow. Very soluble in water. Chem. com. 60*7 chlorine and 39*3 sodium, but often with various impurities. This important mineral is very widely disseminated, either in thick masses, with claj^, anhydrite, and gypsum, or as an efflorescence, covering extensive tracts of country. The most celebrated European deposits occur at Wieliczka and other parts of Galicia, in Hungary, Siebenburg, Mol- davia, Styria, Salzburg (Hallein), in Tyrol (Hall) ; also in Bavaria, Wurtemburg, Switzerland (Bex), and Spain, espe- cially at Cardona. In England the chief deposits are in Cheshire, as at Northwich. In Ireland near Belfast. As an efflorescence it is most abundant on the sandy plains in Brazil, at the foot of the Atlas Mountains in Africa, in Abyssinia, in Arabia, and in the Steppes round the Caspian Sea and Lake Aral. Also as a sublimation among the lavas of Vesuvius and other volcanoes. Dissolved in the water of the ocean, salt lakes, and springs. Used for food, medicine, manures, a flux in melting ores, and in many manufactures. In 1871 the produce of the United King- dom was li million tons, worth £753,000. Sylvine, or chloride of potassium, with 52*4 potassium and 47*6 chlorine, found as a sublimation on Vesuvius, and in the rock-salt of Hallein and Berchtesgaden, agrees in most characters with rock-salt (G. = 1'9...2). 213. Carnallite.— 2 Mg CI -f K CI + 12 H. Ehorabic ; P middle edge 107° 20', odP 118° 37'; mostly massive and granular. Conchoidal fracture. H. = 2...2-5 ; G. = 1*6. Colourless, but generally more or less red from iron peroxide. Deliquesces in the atmosphere, and B.B. fuses very easily, colouring the flame pale violet. Chem. com. 34-2 chloride of magnesium, 26-9 chloride of 212 ALUM — VOLTAITE — ALUNOGENE. [Eock-salt potassium, and 38*9 water; but also traces of rubidium and csesium. Stassfurt, Kalusz in Galicia, and Manan in Persia. Tachydrite, a yellow, pellucid, very soluble salt, found in anhydrite at Stassfurt, has a similar chem. com., except chloride of calcium (21-4) instead of chloride of potassium. Crystals said to be rhombohedral. .... A f ES + (^1, Fe) S' + 24 H = *214. Alum.- | ^-^q ^ I g^a ^4 o]. Tesseral ; 0, sometimes with ooOco and 00 0. Gene- rally fibrous crusts, or as an efflorescence. Cleavage, octahedral imperfect ; fracture conchoidal. H. = 2...2-5 ; G. = 1*75. ..1-9. Translucent. Colourless and white. Taste sweetish astringent. Easily soluble in water. B.B. generally evolves sulphurous fumes. (a,) Potash-alum, with E = k, and 33-7 sulphuric acid, 10-9 alumina, 9*9 potash, and 45*5 water. In the closed tube fuses, intumesces, and yields much water. In the Silurian alum-slates of Sweden, Norway, and Scotland; the coal for- mation, HurletandCampsie in Scotland; the lias nearWhitby; in the brown coals of Hessia and the Khine ; and in the vol- canic formations of the Lipari Islands, Sicily, and the Azores. (b.) Ammonia-alum, with R = NH' 0, and about 4 per cent ammonia and 48 water. In the closed tube it forms a sublimate of sulphate of ammonia. Tschermig in Bohemia. (c.) Soda-alum, with R = Na, and 7 soda and 48 water. Like potash-alum, but more easily soluble. Near Mendoza in South America, the Solfatara at Naples, and Milo. {d) Mag7iesia-alum.—'R = yLg with Mn. Translucent and silky, but soon changes in the air. South Africa, Iquique in Peru (Pickeringite). (e.) Iron-alum {Feather- alum), with R^Fe. Hurlet near Paisley, Morsfield in Ehenish Bavaria, Krisuvig in Iceland (liver salt), 215. VoLTAiTE.— 3 (Fe, K) 8 + 2 (Fe, ^1) 8 + 12 H. Tesseral. Black, brown, or green ; greenish-gray streak. Like alum, but more difficultly soluble in water, and with 4 to 5 potash, and 2 to 5 ahimina. Solfatara of Pozzuoli. 210. Alunogene, Ilair-salt .— Al S'-fl8H. Capillary or acicular, in crusts or reniform masses. H. =- Family. 1 MIEABILITE— MELANTEEITE. 213 184); 1*5. ..2; G. = 1*6. ..1*7. Silky. White, inclining to green or yellow. Tastes like alum. B.B. in closed tube intumesces, yields much water, and is infusible. Chem. com. 36 sul- phuric acid, 15 '4 alumina, 48*6 water. Volcanoes of South America, in coal and brown coal in Germany, and on old walls. 217. MiRABiLiTE, Glauber-salt. — Na S -f 10 H. Monoclinic; 0-72° 15'; ooP(o) 86° 31', V{n) 93° 12', Crystals predominantly OP and ooP°oo {M^ but generally efflorescent crusts. Cleavage, orthodiagonal very perfect ; fracture con- choidal. H. = l-5...2; G. = 1-4... 1*5. Pel- lucid and colourless ; taste cool, saline, and bitter; decomposes readily in the atmo- sphere, and falls into powder. B.B. fuses very easily, and sinks into the charcoal ; colours the flame yellow. Chemi. com. 19*2 soda, 24'8 sulphuric acid, and 56 water. As an efflorescence in quarries, on old walls, or on the earth ; in the water of lakes and springs in Eussia and Egypt, and on Vesuvius in lava. Used in medicine, and in preparing glass and soap. The following, Nos. 218-226, form a sub-family of Metallic salts or Vitriols : — *218. Melanterite, Green or 1 Fe S + 7 H = Iron Vitriol, Copperas. j [Fe 0 . SO' 7 Monoclinic; 0-75° 45'; ooP (/) 101° 34', Foo (p)^ 67° 30' (Fig. 185) ; chiefly stalactitic, reniform, or in crusts. Cleavage, basal very perfect, prismatic less so. H.= 2; G.= l*8...r9. Translucent, rarely transparent ; vit- reous. Leek or mountain green, often with a yellow coating ; streak white. Taste sweetish astringent. Very soluble. B.B. becomes brown, then black and magnetic. Chem. com. 26 protoxide of iron, 29 sulphuric acid, and 45 water. Bodenmais, Eammels- berg in the Harz, Fahlun, Schemnitz, Bilin, and Hurlet near Paisley. Used in dyeing, in manufacturing ink, Prussian blue, and sulphuric acid. Fig. 185. 214 BOTRYOGENE — COPIAPITE — COQUIMBITE. [Bock-salt 219. BOTRYOGENE, | -^. 3 '^2 , o i^j^ 02 , o « tt /.x Eed vitriol. } ^ + 3 Fe S + 36 H (?). Monoclinic; C. = 62° 26^ ooP 119° 56'. Crystals small and short prismatic ; more common botryoidal and reniform. Cleavage, 00 P rather distinct. H. = 2...2*5; G. = 2...2'1. Translucent ; vitreous. Hyacinth-red, orange-yellow, and yellowish-brown ; streak ochre-yellow. Taste slightly astringent. Partially soluble in water, leav- ing a yellow ochre. Chem. com. sulphates of the protoxide and peroxide of iron (48), with 31 water, and about 21 per cent sulphates of magnesia and lime ; the two latter considered mixtures by Berzelius. Fahlun in Sweden. Edmerite from the Harz seems the same. 220. COPIAPITE.— Fe' + 13 H. Six-sided tables, but crystal system uncertain ; also granular. Cleavage perfect. Translucent ; pearly. Yellow. Chem. com. 34 iron peroxide, 42 sulphuric acid, and 24 water. Copiapo in Coquimbo in Chili. Also radiated fibrous masses ; dirty greenish-yellow, incrusting the former. Contain 32 sulphuric acid, and 37 water ; but both are probably mixtures. To these may be added — Fibroferrite, also from Chili. Yellow Iron-ore, from the brown coal at Kolosoruk in Bohemia and Modum in Nor- way. Both are reniform, or compact and earthy. H. 2*5 ...3; G. =27. ..2-9. Colour ochre-yellow. Not soluble in water, with difficulty in hydrochloric acid. Apatelite, reniform earthy, yellow, from Auteuil near Paris, is similar ; also Vitriol ochre from Fahlun ; and 3fis2j, from Rammelsberg in the Harz, containing sulphates of iron, copper, zinc, and other metals, a product of decom- position. 221. CoQUiMBiTE.— Fe S' + 9 H. Hexagonal ; P 58°. Crystals OP, with ocP and P ; usually granular. Cleavage, 00 P imperfect. H. = 2...2'5; G. = 2...2'1. White, also brown, yellow, red, and blue. Taste astringent. Chem. com. 28*5 iron peroxide, 42*6 sulphuric acid, and 2 8 '9 water. Co])iapo in Chili, and Calama in Bolivia. Family.] TECTIZITE — CYANOSE-^GOSLAEITE. 215 222. Tectizite. — Pe, S, H. Ehombic ; dimensions unknown. H. = 1 '5 . . . 2 ; G. = 2 nearly. Vitreous or resinous. Clove-brown. Saxony- near Schwarzenberg, and at Braunsdorf. *223. Cyanose, Blue )Cu'S + 5H = Vitriol. |[CuO.SO' + 5 H^O]. Triclinic. Crystals very unsymmetric ; ooPgc to 00 Poo (r), forms an angle of 79° 19';^F (P) to (^F (T) 127° 40', to ooPoo (n) 120° 50', to ooPoo (r) 103° 27', and 00 P' (T) to ooT (M) 123' 10' (Fig. 186). More often stalactitic, reniform, or as an incrus- tation. Cleavage, along ooP', and 00 T very imperfect ; fracture con- cboidal. H. = 2-5; G. = 2-2. ..2-3. Translucent; vitreous. Blue. Taste very nauseous. Readily soluble in water, from which metallic copper is precipitated by iron. B.B. on charcoal, especially with soda, is easily reduced to metallic copper. Chem. com. 32 protoxide of copper, 32 sulphuric acid, and 36 water. Abundant in the water of some mines, as in the Harz, Hungary, Tyrol, Fahlun, in Anglesea, Cornwall, and Wick- low. Also on the lava of Vesuvius. Used in dyeing, and in forming blue and green pigments. *224. GosLARiTE, White rZn S + 7 Vitriol. i [ZnO.SO' + 7ffO]. Rhombic; ooP 90"" 42', isomorphous with epsomite ; ooP . ocPoo . P (M, 0, I, Fig. 187). Mostly granu- lar, or stalactitic, reniform and encrusting. Cleav- age, brachy diagonal perfect. H. = 2...2*5; G. = 2...2'1. Pellucid; vitreous. White, inclining to gray, yellow, green, or red. Taste nauseous astringent. Chem. com. 28*2 zinc oxide, 27*9 sulphuric acid, and 43*9 water. Rammelsberg in the Harz, Fahlun, Schemnitz, Holywell in Flintshire, and in Cornwall. Used in dyeing and medicine. Fig. 186. Fig. 187. 216 BIEBERITE — NATROX — THERMONATRITE. [BocJc-salt 225. BiEBERiTE, Cobalt Vitriol— Co S + 7 H. Monoclinic : similar to melanterite ; usually stalactitic, or an efflorescence. Pale rose-red. Taste astringent. Chem. com. 20 cobalt oxide, 4 magnesia, 29 sulphuric acid, and 47 water. Bieber near Hanau, and Leogang. Moren- osite is a similar nickel vitriol, fibrous and emerald-green, with 27 nickel-oxide. Eiechelsdorf, and near Lake Huron. 226. JoHANNiTE. — Uran Vitriol. Monoclinic ; C. = 85° 40'; (xP 69°. Crystals similar to trona (Fig. 190), but very small and rare. H. = 2...2'5 ; G. = 3*19. Semitransparent j vitreous. Bright grass- green. Chem. com. a hydrous sulphate of uranium prot- oxide. Joachimsthal and Johann-Georgenstadt. ^227. Natron.— fNa C-f 10 H, or (^[JSV O.CO^+10 0]. Monoclinic ; C. = o7° 40'. Crystals artificial (Fig. 188); with ocP (M) 79° 4r, P (P) 76° 28'. CleavcTge, orthodiagonal distinct. H. = 1... 1*0 j G. = 1'4 ... 1'5. Pellucid ; vitreous. Colourless or grayish-white. B.B. melts easily, colouring the flame yellow. Chem. com. 22 soda, 15 carbonic acid, and 63 water ; but mixed with chloride of sodium, and other salts. Only as an efflorescence on the ground or rocks (lava of Vesuvius and Etna) in various countries, Hungary, Egypt, Tartary, and in mineral springs and lakes. Used in the manufacture of soap, in dyeing, bleaching, and medicine. 228. Thermonatrite. { ["J/q^ c6'+ 0]. ^Ehombic; ooP 2 (d) 107° 50; Poo {o) 83° 50'; with ooPcx) (P) in rectangular tables (Fig. 189). Cleavage, brachydiagonal perfect. H. = 1 "5 ; G. = 1 '5 ... 1 '6. Colour- less. B.B. like natron, but does not melt. Chem. com. 50*1 soda, 35'4 carbonic acid, and 14"5 water. I^atron Family.] TKONA — GAYLUSSITE — BOEAX. 217 lakes of Lagunilla in Colombia, of Lower Egypt, and of the steppes between the Ural and Altai. 229. Trona, Urao.— Na' C' + 4 H. Monoclinic. Crystals OP, ooP^oo (103° 15'), P (M, T, n, Fig. 190). Cleavage, orthodiagonal perfect. H. = 2'5... 3 ; G. = 2*1...2*2. Transparent to translucent ; colourless. Does not decompose in the air. Taste alkaline. Chem. com. 38 soda, 40 carbonic acid, and 22 water. Fezzan and Barbary (Trona), Lagunilla (Urao). 230. GAYLUSSITE.— ISTa C + Ca C + 5 H. Monoclinic ; C. = 78° 27'; ooP 68° 51\ P 110° 30'. Cleavage, ooP imperfect; fracture conchoidal. H. = 2*5; G. = 1*9... 1*95. Transparent ; vitreous ; colourless. Slowly and partially soluble in water. B.B. fuses readily to an opaque bead. Chem. com. 34*5 carbonate of soda, 33*6 carbonate of lime, 30 '4 water, with 1*5 clay. Lagunilla. *231. Borax, TinkaL— Na B^ + 10 H. Monoclinic; C. = 73° 25'; ooP 87°, P 122° 34'; almost isomorphous with augite. Twin crystals frequent. Cleav- age, clinodiagonal perfect; ooP less distinct ; fracture con- choidal, rather brittle. H. = 2 . . . 2 '5 ; G. = 1 '7 . . . 1 -8. Pel- lucid ; resinous. Colourless, but yellowish, greenish, and grayish-white. Taste feebly alkaline and sweetish. B.B. intumesces greatly, becomes black, and melts to a trans- parent bead, colouring the flame yellow, or, with sulphuric acid, green; soluble in 12 parts of cold water. Chem.. com. of the pure salt, 16*4 soda, 3 6 '5 boracic acid, and 47*1 water; but often with 2 phosphoric acid or other im- purities. Shores of salt lakes in Thibet and Nepal ; in Fig. 189. Fig. 190. 218 SASSOLINE— NITRE — NITRATINE. [Rock-solt California, and near Potosi. Borax is prepared from this mineral, and is used for blowpipe experiments, in preparing fine glass, in medicine, and for dyeing. ^^232. Sassolink— B + 3 H, or [B' 0' + 3 ff 0]. Triclinic ; OP: ooPco 75° 30'; usually fine scaly six- sided tables, or fibrous, and stalactitic. Macles frequent. Cleavage, basal very perfect ; sectile and flexible. H. = 1 ; G. = 1'4...1'5. Translucent ; pearly. Grayish or yellowish white. Taste acidulous and slightly bitter. Feels greasy. Easily soluble in boiling, less so in cold water. Froths up and melts in the candle flame to a hard transparent glass, colouring the flame green. Chem. com. 56*3 boracic acid, and 43*7 water. Vulcano in the Lipari Islands, hot springs of Sasso near Sienna, and lagoni of Tuscany. ^233. Nitre, Saltpetre.- f K N, or Ehombic;^oDP {M) 118° 49', 2Poo (P) 70° 55', Poo 109° 52, ooPgc (li) (Fig. 191); isomorphous with arra- gonite. In nature only occurs acicular, capillary, or pulverulent. Cleavage indis- tinct ; fracture conchoidal. H. = 2 ; G. = 1 '9 ... 2 '0. Semitransparent ; vitreous or silky. Colourless, white, or gray. Taste saline and cooling. Deflagrates when placed on hot charcoal ; and B.B. on pla- tina wire melts very easily, colouring the flame violet. Chem. com. 46*6 potash and 53*4 nitric acid, but always more or less mixed. In the limestone caves of many countries, Hungary, Spain, India. Used for producing nitric acid, in glass-making, medicine, and the manufacture of gunpowder. 234. NiTRATiNK— Na N or [Na' 0 + N' 0']. Rhombohedral ; K=10G° 30', isomorphous with dolo- mite. Cleavage rather perfect. H. = l-5...2; G. - 2"1 ...2 "2. Translucent or transparent, with very distinct double refraction ; vitreous. Colourless, or grayish and yellowish-white. Taste saline and cooling. Deflagrates V — M I 1 /~~ Fig. 191. Family.] SAL-AMMONIAC — MASCAGNINE. 219 on hot charcoal. B.B. fuses on platina wire, colouring the flame yellow. Chem. com. 36'6 soda, and 63'4 nitric aci J, but mixed with common salt and other substances. Tara- paca in Chili. Used in the arts as a substitute for nitre ; but deliquesces in the air. 235. NiTROCALCiTE. — Ca N + H. Fibrous or pulverulent. White or gray. Translucent. Taste sharp and bitter. Eeadily soluble in water, and deliquesces in the air; melts slowly on burning charcoal, with slight detonation. Chem. com. 30*8 lime, 5 9 '3 nitric acid, and 9*9 water. Lime- stone caves of Kentucky ; on old walls and limestone rocks. 236. NiTROMAGNESITE. Mg N + H. In the same places, and similar to nitrocalcite. Taste bitter. Chem. com. 24 magnesia, 65 nitric acid, and 1 1 water. *237. Sal-ammoniac— N CI, or [Am CI]. Tesseral; 0, also ooOoo, ooO, and 303. In crusts, stalactites, and earthy or pulverulent. Cleavage, 0 imper- fect ; fracture conchoidal. H. = 1 '5 . . . 2 ; G. = 1*5 ... 1 '6. Pellucid ; vitreous. Colourless, but gray or yellow, rarely green, brown, or black. Taste saline and pungent. B.B. volatilises without fusing ; on copper wire colours the flame bluish-green. Chem. com. (32 per cent ammonia, or) 33*6 ammonium, and 66*4 chlorine. Chiefly occurs as a subli- mate on active volcanoes, Vesuvius, Etna, the Solfatara, Vulcan 0, and Iceland ; also near ignited coal-seams, New- castle, and Scotland. Used in medicine, dyeing, and various metallurgic operations. 238. Mascagnine.— N ff S-fH. Ehombic; ooP 121° 8^ Poo 107° 40'; ooP . ooPoo.P (Fig. 192) ; but chiefly in crusts and stalactites. Cleavage rather perfect ; sectile. H. = 2...2'5 ; G. = 1 '7 ... 1*8. Pellucid, vitreous. Colourless, white or yellowish. Taste pungent and bitter ; easily soluble, and deliquesces. B.B. decrepitates, melts, and volatilises. Chem. com. 25 '9 ammonia, "^-^^^^-^ 60-5 sulphuric acid, and 13*6 water. Near vol- canoes, as Etna, Vesuvius, the Solfatara, the Lipari Islands, in the lagoni near Sienna, and in ignited coal-beds, as at Bradley in Stafi*ordshire. 220 AECANITE — THENAEDITE — EPSOMITE. [Eock-Salt 239. Arcanite, Glaserite. — K S. Ehombic; acute pyramids, with ooP 120° 24', 2Poo , OP, and otlier forms; bat dimorj^hous and also rliombohe- dral, with E 88° 14'. Mostly in crusts, or pulverulent. Cleavage, basal imperfect. H. = 2-5...3j G. = 2"7. Pel- lucid ; vitreous or resinous. Colourless or white. Taste saline, bitter. B.B. decrepitates, fuses, and becomes he- patic. Chem. com. 54 potash, and 46 sulphuric acid. Lavas of Vesuvius and other volcanoes. *240. Thexardite.— Na S. Ehombic ; acute pyramids P, with OP and ocP, in crusts and druses. Cleavage, basal rather perfect ; fracture uneven. H. = 2*5 ; G. 2*6. ..2*7. Pellucid, vitreous. White. Taste feebly saline. B.B. colours the flame deep yellow, and fuses. Chem. com. 43*82 soda, and 56*18 sul- phuric acid. Salinas d'Espartinas near Aranjuez, and Tara- paca. Used for preparing soda. 241. LowEiTK— 2 (Na S + Mg S) + 5 H. Tetragonal, but only compact ; cleavage, basal distinct. H. = 2*5...3; G. - 2*376. Vitreous. Yellowish-white to flesh-red. Taste slightly saline. Chem. com. 20 soda, 13 magnesia, 52 sulphuric acid, and 15 water. Ischl. -242. EPSOMITE, Epsom-salt. | '^If^^Q^ + 7 Q]. Ehombic ; P mostly hemihedric, ooP 90° 38'; ocP (M) . (xPoo (o) . P (0 (Fig. 193). Granular, fibrous, or earthy. Cleavage, brachy- diagonal perfect. H. = 2...2*5; G. = 1*75. Pellucid; vitreous ; and white. Taste saline, bitter. B.B. on charcoal fuses, incandesces, and shows alkaline reaction ; with solution of cobalt be- comes pale rose-red. Chem. com. 16*32 magnesia, 32*53 sulphuric acid, and 51*15 water. Efflorescence on various rocks, as at Hurlet near Paisley, Idria, ]\lontmartre, and Freiberg; on the ground in Spain, and the Eussian steppes ; in mineral waters, as at Ejisom in Surrey (Epsom salts). Said- Family.] KIESERITE— blOdite. 221 schiitz and Seidlitz in Bohemia. Used in medicine and in preparing magnesia. 243. KiESERiTE, Martinsite. — Mg S + H. Ehombic, but chiefly massive. G. = 2*52. Pellucid; grayish- white. Slowly soluble in water. Chem. com. 29 magnesia, 58 sulphuric acid, and 13 water. In beds at Stassfurt. 244. Blodite, Astrakanite.— (Mg Na) S + 2 H. Monoclinicj C. = 100° 43'; ooP2 = 112'^ 55' in pris- matic crystals, or efflorescent. H. = 3*5 ; Gr. = 2'2. Trans- parent. White or red. Chem. com. 47*9 sulphuric acid, 8*5 soda, 12 magnesia, and 21 '5 water. Salt lakes on the Volga near Astrakan, Ischl, Stassfurt, and near Mendoza in South America. Reussin from Seidlitz similar, but a mixture. Kainite from Stassfurt, and Kalusz in Galicia, fine granular, yellow or light-gray masses, is chiefly sulphates of magnesia and potash with water, but analyses vary much, and probably a mixture. 222 THE SPARKY lEON ORES. [S])arry Iron Order III. SALINE OEES. Resemble the saline stones both in external characters and chemical composition, forming almost a parallel series, with metallic oxides in place of the earthy bases. Lime or magnesia occasionally occur in more or less extent, and the acid element is one of the common acids of the chemist. Crystallisation in the carbonates is often rliombohedral, in the others monoclinic or rhombic. Other systems only occur in rare cases. Hardness is not high, mostly 3... 4, in a few as high as 5, or as low as 2. Their specific gravity is high, from the metallic element in their composition; mostly from 3... 4 in the salts of iron or copper, and from 5... 7 or 8 in the salts of lead and some others. They are almost all soluble in acids, and the carbonates effervesce. B.B. mostly fusible, decomposed, or reduced, and with fluxes form coloured glasses characteristic of the different metals. They are mostly translucent, rarely transparent. Their lustre is often pearly or vitreous. Some are white, others are coloured, and these colours are now characteristic of the metal as the essential element. *Family I. — The Sparry Iron Ores. Crystallisation and cleavage rhombohedral. H. = 3'5... 5 ; G. = 3-3...4'5. They are all soluble in acids, and often effervesce. B.B. they are all infusible, but decomposed, and leave a magnetic residue, or show reactions of metals. The colours are white, but often with a brown, yellow, or red tinge, especially when weathered. They chiefly occur in veins. Family.] SIDERITE — CLA.Y IRONSTONE. 223 **245. SiDERiTE, Sparry Iron, Cr^TFeO CO'l Spharosiderite, Chalybite. J L • J- Hexagonal and rhombohedral ; E 107°. Chiefly E, often curved, saddle-shaped, or lenticular, occasionally OE, — |E, 00 E, — 2E, 00 P2. Frequently fine or coarse granu- lar, more rarely botryoidal or reniform (Sphcerosiderite). Cleavage, rhombohedral along E perfect. Brittle. H. = 3'5...4*5 ; G. = 3'7...3*9. Translucent in various degrees, becoming opaque when weathered ; vitreous or pearly. Earely white, generally yellowish-gray or yellowish-brown, changing to red or blackish-brown on exposure. B.B. in- fusible, but becomes black and magnetic ; with borax and salt of phosphorus shows reaction for iron ; with soda usually for manganese. In acids soluble with effervescence. Chem. com. carbonate of iron, with 62*1 protoxide of iron and 3 7' 9 carbonic acid, but usually 0*5 to 10, or even 25 protoxide of manganese, 0*2 to 15 magnesia, and O'l to 2 lime. In beds or masses, in Styria, Carinthia, and West- phalia ; in veins in Anhalt and the Harz ; also in the Py- renees, and the Basque provinces of Spain, as near Bilboa. In crystals at Joachimstlial, Freiberg, Klausthal, Beeral- stone in Devonshire, Alston Moor in Cumberland, and in many of the tin mines of Cornwall. Clay ironstone, gray, blue, brown, or black, G-.= 2*8... 3*5 ; H. = 3'5...4*5-, is an impure variety. It occurs chiefly in slate-clay or marls, in layers or nodular masses, especially in the coal formation of Britain, Belgium, and Silesia. These ores contain 50 to 85 per cent carbonate of iron, and yield 25 to 42 metal. The Lanarkshire blackband contains 70 carbonate of iron, 23 carbonaceous matter, 7 of silica, alumina and lime, and yields 33*7 iron. In 1871 England produced 4,379,370 tons; Wales, 1,087,809 ; and Scot- land, 1,160,000 ; or, in all, 6,627,179 tons pig-iron, worth at. the place of production about seventeen millions sterling. Junkerite, from Brittany, is a mere variety. Oligon spar contains 20 per cent or more manganese protoxide ; Sidero- plesite, from Salzburg, 10*4 magnesia. Ankerite. — E 106° 12', but mostly massive and granu- lar. G. ==2*9...3'1 ; otherwise like siderite. Contains 51 224 DIALOGITE — PAEISITE. [Sparry Iron carbonate of lime, 12 to 33 carbonate of magnesia, 12 to 36 carbonate of iron, and 0 to 3 carbonate of manganese protoxide. Styria. Used as an ore or flux. 246. Dialogue, Eed Manganese. — Mn C. Hexagonal, rhomb oliedral j E 106° 56'; K and-JE, sometimes OE and ooP 2. Crystals often curved, lenticular, or saddle-shaped ; also spherical, reniform, and columnar or granular. Cleavage, E perfect. R. = S'5 ..A'5 ; G = 3-3... 3-6. Translucent; vitreous or pearly. Eose-red to flesh- red ; streak white. B.B. decrepitates and becomes gray or black, but is infusible ; with borax reaction for manganese ; the powder soluble with eff'ervescence in warm h. acid. Chem. com. 62 manganese protoxide and 38 carbonic acid, but usually mixed with carbonates of lime 0 to 1 3, mag- nesia 0 to 7, or iron 0 to 15. Freiberg, Schemnitz, Kap- nik, Nagyag, Elbingerode, and near Sargans. At the latter, also hydrated, and fibrous silky {JViserite) ; compact in Hessia and Glendree, Ireland. 247. Manganocalcite. — (Mn, Ca, Fe) C, Ehombic ; in prisms like arragonite, and bears the same relation to dialogite that arragonite does to calc-spar. H. = 4...o ; G. = 3*03. Eed or reddish- white ; vitreous. Schemnitz. 248. Lanthanite. — La C -f 3 H. . Ehombic; ooP 92° 46'; small tabular crystals; usually granular or earthy. Cleavage basal. H. = 2 ; G. = 2*7. Dull or pearly. White or yellowish. B.B. becomes brown- ish-yellow ; soluble in acids with eff'ervescence. Chem. com. 21 carbonic acid, 55 lanthanium oxide, and 24 water. Bastnaes in Sweden, Lehigh in Pennsylvania. 249. Parisite.— Ce C, Ca F, H. Hexagonal; P 164° 58'. Cleavage, basal very perfect. H. = 4*5 ; G. ^- 4*35. Vitreous ; on tlie cleavage-planes pearly. Brownish-yellow inclining to red. B.B. infusible and phosphoresces. Chem. com. 23*5 carbonic acid, 42*5 protoxide of cerium, 8*2 lanthanium oxide, 9 '6 didymium oxide, 2 '8 lime, lO'l fluoride of calcium, and 2*2 fluoride of cerium. Emerald mines of the Musso Valley in New Granada, Ural. Family.] SMITHSONITE — GALMET. 225 *250. Smithsonite, Calamine.— Zn C = [Zn 0 . CO']. Hexagonal-rhombohedral ; E 107° 40'; E, 4E, and E3. The crystals generally small, obtuse-edged,' and rounded. Usually reniform, stalactitic, and laminar or granular. Cleavage, E perfect but curved ; fracture uneven conchoidal; brittle.' H. = 5 ; G. = 4-1 ...4-5. Translucent or opaque ; pearly or vitreous. Colourless, but often pale grayish-yellow, brown, or green. B.B. becomes white, on charcoal forms a ring, yellow when hot, white when cold ; soluble in acids with effervescence ; also in solution of pot- ash. Chem. com. 6 4 '8 zinc oxide, and 35*2 carbonic acid, but with protoxide of iron 2 to 3, or of manganese 3 to 7,' lime 1 to 2, or magnesia 0 to 3. This mineral occurs in beds or veins in the crystalline and stratified rocks. It is most common in limestone, and 3S often associated with calc-spar, quartz, blende, and ores of iron and lead. Chessy near Lyons, Altenberg near Aix- la-Chapelle, Brillon in WestphaHa, Tarnowitz in Silesia, Hungary, Siberia ; also Mendip in Somersetshire, Matlock m Derbyshire, Wanlockh^ad and Leadhills in Scotland; compact at Alston Moor. Zinc is obtained chiefly from this mineral. In Silesia also cadmium. Varieties ^ve—Kapnite, with 15 to 37 per cent of iron protoxide. Zinc-Uoom, reniform, earthy, pale-yellow, and sinning streak; seems a mere product of decomposition. Bleiberg and Eaibel in Carinthia. Herrente, green, with 3 to 4 per cent copper oxide ; from Mexico. *251. Galmet, Electric f Zn' Si -fH = Calamine. j [2 Zn 0 . Si 0' + ff 01. Ehombic, and hemimorphic ; 2 P 2 (P)_with polar edges 101° 35', and 132° 26'; ooP(6^) 103^ 50', Poo {o) 117° 14', Poo (/) 128° 55'; common form odPoo {s) . ooP . Poo (Fig. 194). Also columnar, fibrous, granular, and earthy. Cleav- age, prismatic along goP very perfect, along Poo perfect. H. = 5 ; G. = 3-3...3'5. Transparent to translucent ; vitre- ous and pearly. Colourless or white, but often light gray, also yellow, green, brown, and blue ; becomes electric by Q 226 WILLEMITE — VIVIANITE. [Iron Salts d heat. B.B. decrepitates slightly, but is infusible, with cobalt solution blue and partly green ; readily soluble in acids, and gelatinises. Chem. com. 25 silica, 67*5 zinc oxide, and 7 '5 water. With calamine, as at Eaibel and Bleiberg in Carinthia, Aix-la- Chapelle, Iserlohn, Tarnowitz, and Nerts- chinsk ; Pennsylvania and Virginia ; also Mendip Hills, Matlock in Derbyshire, and Wanlockhead. Used as an ore of zinc. 252. WiLLEMiTE, Troostite.^ — Zn Si. Ehombohedral ; E 128° 30' . ooE. E ; also granular and reniform. Cleavage, basal rather perfect, ooE imperfect ; brittle. H. ^ 4-5 ; G. = 4-1. ..4-2. Translucent or trans- parent ; dull resinous. White, yellowish, or brown. B.B. in closed tube yields no water, otherwise like galmei. Chem. com. 73 zinc oxide and 27 silica, with 0 to 9 prot- oxide of manganese, 0 to 5 iron protoxide, and 0 to 3 magnesia. Aix-la-Chapelle, Liege, Eaibel, also Sterhng and Franklin in New Jersey. Family II. — Iron Salts. Crystallisation predominantly rhombic or monoclinic. H. - 2...5-5 ; Gr. 2-2...4-0. They are all soluble in acids, and many easily. B.B. all fusible, and also often easily so. Their colours are often brown, or dark blue and dark green ; the streak yellow or red. They are chiefly phosphates or arseniates of iron. The phosphates B.B., moistened with sulphuric acid, colour the flame bluish-green. The arseni- ates B.B. in the reducing flame, or with carbonate of soda, evolve odour of arsenic. •^253. ViviANiTE, Blue f iV P -f- 8 H = Iron. t Fe 0 . 0' 4- 8 0]. Monoclinic ; C. = 75° 34', c^P 108° 2', P 120° 20^ Po) 54° 40'. Crystals prismatic (Fig. 105); also spherical or reniform, and fibrous or eartliy. Cleavage, clinodiagonal, very perfect ; thin lamina3 flexible. H. = 2 ; G. = 2-G...2-7. Family.'] DUFE^NITE — TEIPLITE. 227 Translucent or transparent ; vitreous, or bright pearly on cleavage. Indigo-blue to blackish-green ; streak bluish-white, but soon becomes blue on exposure. The white earthy variety also changes to blue in the air ; the dry crushed powder is liver-brown. In the closed tube yields much water, intu- mesces, and becomes spotted with gray and red. B.B. on charcoal becomes red, and then fuses to a gray, shining, magnetic granule j easily soluble in h. or nitric acid ; becomes black in warm solu- tion of potash. Chem. com. the colourless vivianite is a hydrous phosphate of iron protoxide, with 43 iron protoxide, 28 phosphoric acid, and 29 water • but after exposure part of the water is exchanged for oxy- gen, and to six molecules of the above one of i^Q^ P' + 8 H) is added, when it acquires a blue colour, and contains 29 phosphoric acid, 33-1 iron protoxide, 12 '2 iron peroxide, and 25-7 water. Transparent indigo- coloured crystals at St. Agnes in Cornwall, and Allentown and Imleytown in New Jersey, Earthy in Cornwall, Styria, North America, Green- land, and New Zealand, and in peat mosses in Northern Germany, Sweden, Norway, and the Zetland Isles. Used as a pigment. Mullicite and Anglarite are varieties. Beraunite. — Eadiated; red or brown; streak ochre- yellow ; from Beraun, Bohemia, is a decomposed product. Kakoxene, yellow and silky, from Zbirow in Bohemia, is also similar. 254. DuFR^NiTE, Green Iron Earth. — 2 Pe' P + 5 H. Ehombic; ooP about 123°j spherical orreniform. Cleav- age brachy diagonal ; very brittle. H. - 3...3-5 G. = 3*3 ...3-4. Translucent on the edges, or opaque ; shining or dull. Dirty, leek, or blackish green ; streak siskin-green. B.B. fuses readily to a porous, black, non-magnetic globule ; soluble in h. acid. Chem. com. 63 iron peroxide, 28 phos- phoric acid, and 9 water. Westerwald, Hirschberg, and Limoges. Kraurite is the same. 255. Triplite.— (Fe, Mn)' P + E F. Monoclinic (?) ; only granular. Cleavage, in two direc- tions at right angles; fracture conchoidal. H. -5...5-5; a 228 ZWIESELITE — TEIPHYLIXE— MOXAZITE. [Iron Salts G. = 3"6...3'8. Translucent or opaque ; resinous. Chestnut or blackish brown ; streak yellowish-gray. B.B. on char- coal fuses easily, with strong intumescence, to a black niag- netic globule ; soluble in s. acid, with reaction of fluorine. Chem. com. iron and manganese protoxides, with 33 phos- phoric acid and 7 or 8 fluorine. Limoges, Schlaggenwald. 256. ZwiESELiTE, Eisenapatit.— (Fe, Mn)' P 4- Fe F. Ehombic, but only massive. Cleavage, basal rather perfect, two others imperfect. R = 4-0...5 j G. 3'9o,.A. Brown ; streak yellow. B.B. decrepitates and fuses easily. Chem. com. like triplite, and identical or i^omorphous. Zwiesel in Bavaria. Alluaudite, clove-brown, from Chante- loube, near Limoges, is altered triplite. 257. Triphylixe.— (2 Fe + Li) P. Ehombic; ccP 133''; chiefly granular. Cleavage, basal perfect, prismatic and diagonal imperfect. H. = 5 ; G. = 3 '6. Translucent on the edges ; resinous. Greenish-gray with blue spots. B.B. fuses very easily to a dark steel- gray magnetic bead ; easily soluble in h. acid. Chem. com. 45 phosphoric acid, 40 iron protoxide, o'o manganese prot- oxide, 7*5 lithia, and 2 magnesia. Bodenmais in Bavaria, Norwich in Massachusetts. Tetra])hyline or Ferowskbie, from Tammela in Finland, is similar. 258. MoxAZiTE.— (Ce, La)' P. Monoclinic; C. - 76^ 14', ccV 93° 23'; crystals (like Fig. 196), thick, tabular, or very short prismatic. Cleav- age, basal perfect. H. = 5...5-5 ; G. = 4-9. ..5-25. Trans- e lucent on the edges ; dull resinous. Flesh- red, hyacinth-red, and reddish-brown. B.B. infusible ; moistened with sulphuric acid, colours the flame green ; soluble in li. acid. Chem. com. 28 phosphoric acid, 37 to 46 cerium protox- ide, 24 to 27 lantlianium oxide (18 thorina '?), with 2 tin oxide, 1*5 lime, and some magnesia and manganese. Miask, Norwich in Connecticut {Edicardslfe), and New Granada. Monazitoid. — G. 5-28; l)rown,with 18 phosphoric acid; probably a variety. Also Ere/nile, from N. America. Family.] CKYPTOLITE — PISSOPHANE. 229 259. Cryptolite. — Ce'P. Acicular crystals, embedded in apatite. G-. = 4'6. Trans- parent. Pale wine-yellow. Powder soluble in con. s. acid. Wohler found 73*70 cerium protoxide, 27*37 phosphoric acid, and 1 *5 1 iron protoxide. Arendal. 260. HuREAULiTE.— (Mn, Fe)^ P'-f 5 H. Monoclinic ;C.-89°27;ooP61°j fracture conchoidal. H. = 3*5 j G. = 3*2. Translucent ; resinous. Eeddish- yellow or brown. B.B. fuses easily to a black metallic globule ; soluble in acids. Chem. com. 39 phosphoric acid, 8 iron protoxide, 42 manganese protoxide, and 12 water. Bureaux near Limoges. Heterozite. — H. = 5 ; G, = 3*5. Opaque ; vitreous or resinous. Dark-violet or blue to greenish-gray; streak violet-blue or crimson-red. Hureaux. Probably decom- posed triphyline. 261. DiADOCHiTE.— Fe P' + 4 Pe S -f 32 H. Eeniform and stalactitic. Fracture conchoidal. H. 3 ; G. = 1*9... 2*0. Eesinous ; vitreous. Yellow or yel- lowish-brown ; streak white. B.B. intumesces and fuses on the edges to a black magnetic enamel. Chem. com. 36*7 iron peroxide, 14*8 phosphoric acid, 15*2 sulphuric acid, and 30*3 water. Graf en thai and Saalfeld in Thuringia. 262. Delvauxene, Delvauxite.— Pe' P + 24 H. Massive and earthy. H. 2*5 ; G. = 1*85. Eeddish or blackish-brown or yellow. B.B. decrepitates, and fuses to a gray magnetic bead. In h. acid forms a brown solu- tion. Chem. com. 35*8 iron peroxide, 48*3 water, and 15*9 phosphoric acid. yis6 in Belgium. Perhaps only dufrenite with water. Delvauxene, from Leoben in Styria, with less water, is probably distinct. 263. PISSOPHANE.— (Al, Pe)' S + 15 H. Stalactitic ; fracture conchoidal ; very easily frangible. H. = 2 ; G. = 1*9...2. Transparent or translucent ; vitreous. Olive-green to liver-brown ; streak greenish-white to pale yellow. B.B. becomes black; easily soluble in h. acid. Chem. com. 7 to 35 alumina, 10 to 40 iron peroxide, 12 sulphuric acid, and 41 water. Saalfeld and Eeichenbach in Saxony. 230 PITTICITE — SYMPLESITE— SCOHODITE. [Iron Salts KarpJwsiderite, reniform opaque, resinous, and straw- yellow, with a greasy feel, is related. H. = 4*5 ; G. = 2 '5. B.B. becomes red and fuses to a black magnetic bead; consists of hydrous sulphate of iron. Labrador. ^ 264. PiTTiciTE, Iron Sinter.— Fe' S' + 2 Pe As + 24 H. Eeniform and stalactitic ; brittle ; fracture conchoidal. H. = 2...3 ; Gr. = 2 -3... 2*5. Translucent, or on the edges ; resinous, inclining to vitreous. Yellowish, reddish, or blackish-brown, sometimes in spots or stripes j streak light- yellow, or white. B.B. on charcoal fuses easily, with effervescence and strong arsenical fumes, to a black mag- netic globule ; easily soluble in h. acid to a yellow fluid. Chem. com. 35 iron peroxide, 26 arsenic acid, 14 sulphuric acid, and 24 water. In many old mines, as Freiberg and Schneeberg. 265. Symplesite. Monoclinic, like gypsum ; in very fine prismatic crystals or groups. Cleavage perfect. H. = 2'5 ; G. = 2'957. Transparent or translucent ; vitreous, pearly on the cleav- age. Pale indigo to celadine-green, with bluish-white streak. B.B. emits arsenic odours, becomes black and magnetic, but does not fuse. Chem. com. arseniate of iron protoxide with water. Lobenstein in Reuss, Lolling. 266. SCORODITE, Neoctese. — Fe As + 4 H. Ehombic; P, with polar edges 103° 5^ and 114° 34'. h Crystals P (P) ooPoo and ooPoo (r); also OP (A), ooP 2(6^)120° 10', and 2 Poo (m) 132° (Fig. 197) ; also columnar and fibrous. Cleavage imperfect ; rather brittle. H. = 3*5 ...4; G. = 3-1. ..3-2. Translucent; vitreous. Leek-green to greenish- black, also indigo-blue, red, and brown. In closed tube yields water and becomes yellow. B.B. on char- coal fuses easily, emitting arsenic vapours, to a gray magnetic slag ; easily soluble in h. (not in nitric) acid, forming a brown Family.] AESENIOSIDERITE — PHAEMACOSIDERITE. 231 solution. Chem. com. 49*8 arsenic acid, 34*6 iron perox- ide, and 15*6 water. St. Austle in Cornwall, near Limoges in France, Schwarzenberg, Lolling in Carinthia, Brazil, and Siberia. 267. Arseniosiderite. — Ca^ As + Fe' As + 6 H. Spherical and fibrous ; friable, and leaves a mark on paper. H. = 1...2; G. = 3'52...3*88. Opaque; metallic pearly. Ochre-brown, becoming darker in the air ; streak brownish-yellow. B.B. fuses easily, with reaction for iron and arsenic. Chem. com. 38 arsenic acid, 39 iron peroxide, 14 lime, and 9 water. Eomaneche near Ma^on. 268. Pharmacosiderite, Cube Ore. — ¥e* As^ -f 15 IT. Tesseral and tetrahedral; usually ooOoo , with or ooO. Cleavage, tesseral very imperfect ; rather brittle. H. = 2*5 ; G-. = 2 '9 . . . 3'0. Semitransparent to translucent ; adamantine or resinous. Olive to emerald green, honey-yellow, and brown ; streak straw-yellow. Pyro-electric. In closed tube yields water and becomes red. B.B. on charcoal fuses easily to a steel-gray magnetic slag ; easily soluble in acids. Chem. com. 43 arsenic acid, 40 iron peroxide, and 17 water. Huel Gorland, Huel Unity, and Carharrak in Cornwall ; Burdle Gill in Cumberland ; also Lobenstein in Reuss, Schwarzenberg in Saxony, North America ; and the gold- quartz of Australia. JBeudantite, rhombohedral ; R 91° 18'. H. = 3*5 ; G. = 4. Vitreous ; olive-green, streak greenish-yellow. Chem. com. oxides of iron and lead, with arsenic acid, phosphoric acid, and water ; but probably a mixture of pharmacosiderite with sulphate of lead. Horhausen in Nassau; Cork in Ireland. *Family III. — Copper Salts. Crystallisation generally rhombic and monoclinic. Hard- ness generally from 2... 3 '5, but a few as low as 1.,.2, others 4 ... 5. Gravity 2 ... 4, but mostly 3 ... 4. The colours are predominantly green, and rarely blue. They are all 232 DIOPTASE — CHRYSOCOLLA — AZURITE. [Co]jper Salts soluble in acids, and mostly easily so. Mostly fusible B.B. and on charcoal, when moistened with hydrochloric acid, the copper is known by colouring the flame blue. With soda they are reduced to metallic copper. They are, with a few exceptions, compounds of copper with one of the common acids, and some used as ores of that metal. They occur especially in veins. 269. DioPTASE, Emerald Copper.— Cu Si + H. Hexagonal and rhombohedral ; E 125° 54^; a)P2 (5) . - 2E (r) 95° 28' (Fig. 198). Cleavage, E perfect; brittle. H. = 5; G. = 3-2...3-3. Transparent or translucent ; vitreous. Emerald-green, rarely verdigris or blackish green ; streak green. B.B. in the outer flame becomes black, in the inner red, but is infusible ; soluble, and gelatinises in h. or s. acid, and also in ammonia. Chem. com. 38*7 silica, 50 copper prot- oxide, and 11 '3 water. Altyntubeh in the Kirgis Steppe. 270. Chrysocolla, Copper-green. — Cu Si + 2 H. Botryoidal, reniform, or investing ; brittle ; fracture conchoidal, and fine splintery. H. = 2...3; G-. = 2*0. ..2*3; Translucent or semitransparent ; weak resinous. Verdigris to emerald green or azure-blue ; streak greenish-white. B.B. and with acids like dioptase. Chem. com. 34*83 silica, 44*94 copper protoxide, and 20*23 water. Saxony, Bavaria, Ural, Cornwall, Hungary, the Tyrol, Spain, the Harz {Siliceous malachite), Mexico, and Chili. fCu^C-^ + H = ^oppei. I [3 Q 2 CO' -f ff 0]. Monoclinic ; C. - 87° 39', ooP {M) 99° 32', - P (Z;') 106° 14'. Crystals OP . ooP . ocP^'oo . - P, (or h, M, s, Jc, in Fig. 199, but in another position) ; also radiated and earthy. Cleavage, clinodomatic (P) 59° 14', rather perfect ; fracture conchoidal, or splintery. H. = 3*5...4*2 ; G. = 3*7 ...3*8. Translucent or opaque ; vitreous. Azure-blue, the Fig. 198. *271. AzuRiTE, Blue < Family^ MALACHITE. 233 Fig. 199. Australia; also Eedruth in Wanlockhead : massive in earthy varieties (and streak) smalt-blue. B.B. on charcoal fuses and yields a grain of copper; soluble with efferves- cence in acids and also in ammonia. Chem. com. 69*1 protoxide of copper, 25*7 carbonic acid, and 5*2 water. Crystals at Chessy near Lyons, in Siberia, Moldawa in the Bannat ; Burra-Burra, Cornwall, Alston Moor and Cornwall, Thuringia, the Harz, Hessia, and the Ural. Common as a pseudomorph. Valued as an ore of copper. **272 Malachite | C^'C + H=.[2CuO . COWO],or Z i Z. MALACHITE. | [Qu 0 . 0 + Cu 0 . CO^]. Monoclinic; C. = 6r 50^ ooP 104° 20'; crystals ooP (M) . ooP^oo (i) . OP (P), in macles (Fig. 200). In general acicular, scaly, or reniform, stalactitic, and radiated fibrous. Cleavage, basal and clinodiagonal very perfect. H. = 3-5 ...4; G-. = 3*6...4*0. Transparent or translucent on the edges ; adamantine, vitreous, silky or dull. Emerald and other shades of green ; streak apple-green. B.B. and with acids, like azurite. Chem. com. 71*8 copper protoxide. (•=57*5 copper), 20 carbonic acid, and 8*2 water. Crystalline at Eheinbreitenbach on the Rhine, and Zellerfeld in the Harz ; fibrous and compact at Chessy in France, Siberia, the Ural, Saalfeld in Thuringia, Moldawa in the Bannat, Sandlodge in Zetland, Cornwall, Wales, and Ire- land, and in North America, and Australia. Frequent pseudomorph after copper and its after calcite and cerussite. It is a valuable ore of copper, and the finer varieties are prized for ornamental purposes. Lime-Malachite. — Eeniform, botryoidal, and radiated fibrous; brittle. H. = 2*5. Silky; verdigris-green. B.B. blackens and fuses to a black slag; soluble in h. acid, leaving gelatinous gypsum. Seems a hydrous carbonate of copper and lime, with sulphate of lime and some iron. Lauterberg in the Harz. Mysorine, compact, blackish- Fig. 200. ores ; also 234 AUPJCHALCITE — TIROLITE. [Copper Salts brown, and soft, G. = 2*62, is a mixture of a carbonate of copper with iron peroxide. Mysore in the East Indies. 273. AuRiCHALCiTE.— 2 Cu C + 3 Zn H. Acicular. H. = 2. Translucent, pearly, and verdigris- green. B.B. on charcoal in the inner flame de23osites zinc oxide, and with fluxes shows reaction for copper; soluble with efferyescence in h. acid. Chem. com. 29*2 copper protoxide, 44*7 zinc oxide, 16 '2 carbonic acid, and 9*9 water. Lok- tefskoi in the Altai ; Matlock in Derbyshire. Buratite, azure-blue, like aurichalcite, but perhaps mixed with lime. Loktefskoi, Chessy, and Volterra. 274. Chalcophyllite, ( Cu^ As + 23 H, or Copper-mica. \ c,,« As + 1 2 H. Hexagonal and rhombohedral j E 69° 48'. Crystals, OE (o) . E (Fig. 201). Cleavage, basal very perfect; sec- tile. H. = 2 j Gr. = 2'4. . .2-6. Translucent or transparent ; vitreous inclining to adamantine ; pearly on OE. Emerald soluble in acids and ammonia. Chem. com. 49 "6 copper protoxide, 18 arsenic acid, and 32*4 water; or 51 '6 copper protoxide, 25 arsenic acid, and 23*4 water; but also 2 alumina and I'o phosphoric acid. Tingtang, Huel Gor- land and Huel Unity Mines near Eedruth ; also Saida in Saxony, and Moldawa in the Bannat. 275. TiROLiTE.— Cu^ As -I- 5 H 4- Ca C. Ehombic (1) ; reniform, or radiating foliated. Cleavage, basal very perfect ; sectile. Thin lamim-e flexible. H. = 1 '5 ... 2 ; G. = 3 ... 3* 2. Translucent ; pearly or vitreous. Yerdigris-green to azure-blue ; streak paler. B.B. decrepi- tates violently and fuses to a steel-gray bead ; soluble in acids, evolving carbonic acid. Chem. com. 50 '4 copper oxide, 29*1 arsenic acid, 94 water, and 11 '4 carbonate of lime. Analyses give more water, and the carbonate of lime is essential. Falkenstein in Tyrol, in Hungary, Eeichelsdorf, Fig. 201. to grass or verdigris green ; streak light- green. B.B. decrepitates ^do- lently, emits arsenical vapours, and fuses to a gray metallic grain; easily Family.] ERINITE — LIKOCONITE— OLIVENITE. 235 Saalfeld, Piombino in Italy, in Asturia and at Linares in Spain, and Matlock in Derbyshire. 276. Erinite.— Cu^ As+ 2 H. Eeniform and foliated ; conchoidal fracture. H. = 4*5 ...5; G. = 4...4-l. Translucent on the edges; dull resi- nous. Emerald or grass green ; streak similar. Chem. com. 59*9 copper protoxide, 34*7 arsenic acid, and 5*4 water. Said from Limerick, but probably Cornwall. Corn- wallite is similar, but dark-green, and with 13 water or 5 H. Cornwall. 277. Liroconite. — Cu^ As + Al As + 24 H. Monoclinic ; C. - 88° 33' ; ooP {d) 61° 31', Foo {o) 74° 21' (Fig. 202). Cleavage, prismatic imperfect. H. = 2... 2*5 ; G. = 2-8...3'0. Translucent ; vitreous, or resinous on fracture. Azure-blue to verdigris- green ; streak paler. In the closed tube does not decrepitate, but becomes green j then ignites and brown. B.B, on charcoal emits arsenical vapours and fuses ; soluble in acids and am- monia. Chem. com. 36*6 copper protoxide, 11*9 alumina, 2 6 '6 arsenic acid, and Eedruth ; also Herrengrund in Hungary. ^^no r^ f Cu^ (^S P) + H, OT -278. Olivenite. | ^4 qIi 0 . As^ 6^ + H Ehombic; ooP {r) 92° 30', Poo (/) 110' (Fig. 203) ; also spherical and reni- form, and columnar or fibrous. Cleav- age (r) and (l) very imperfect. H. = 3 ; G. - 4-1... 4-6. Pellucid in all degrees ; vitreous, resinous, or silky. Leek, olive, or blackish green, also yellow and brown ; streak olive-green or brown. B.B. in the forceps fuses easily to a dark-brown adamantine bead covered with radiating crystals ; on charcoal detonates, emits arsenical vapours, and is reduced ; soluble in acids and ammonia. Chem. com. 56*5 copper protoxide, Fig. 202. 24*9 water. Near 0.] _ 50'; ooPoo(w) 236 EUCHKOITE — PHOSPHOROCHALCITE. [Copper Salts 39*5 arsenic acid, and 4 water, but also 1 to 6 phosphoric acid. Carharrach, Tin Croft, Gwennap, and St. Day, in Cornwall; also Alston Moor, Thuringia, Tyrol, Siberia, Chili. 279. EucHROiTE. — Cu^ As + 7 H. Ehombicj ooP {M) 117° 20', Poo {n) 80° 52', with ooP2 (0, and OP (P), (Fig. 204). Cleav- age M and n imperfect ; rather brittle. H. = 3-5...4; = 3-35. ..3-45. Trans- parent or translucent ; vitreous. Eme- rald or leek green ; streak verdigris- green. B.B. in forceps fuses to a green- ish-brown crystallised mass ; easily soluble in nitric acid. Chem. com. 47 copper protoxide, 34 arsenic acid, and Libethen in Hungary. Fig. 204. 19 water. 280. Klinoclase, Aphanese, Abichite. — Cu' As-1-3 H. Monoclinic; C. = 80° 30', ooP56°; also hemispherical radiated masses. Cleavage, basal highly perfect. H. = 2*5 ...3 ; G. = 4'2...4'4. Translucent or opaque ; vitreous ; pearly on the cleavage. Dark verdigris-green inclining to sky-blue ; streak bluish-green. B.B. becomes black, and is reduced ; soluble in acids and ammonia. Chem. com. 62-6 copper protoxide, 30*3 arsenic acid, and 7*1 water. Corn- wall, Tavistock, and the Erzgebirge. 281. PHOSPHOROCHALCITE, Lumiite. — Cu' P + 3 H. Monoclinic ; crystals ooP''2 (/) 38° 56', P (P) 117° 49^ with OP [a) and ooP^'oo (e) (Fig. 205); usually small and indistinct, more common in spherical or reniform, and radiated fibrous masses. Cleavage, (e) imper- f(^ct ; fracture uneven and splintery. 11.-5; G. = 4-1 ...4-3. Translucent, or on the edges; adamantine or resin- ous. IMackisli, emerald, or verdigris green. B.B. decrepitates, or blackens and fuses to a black Fig. 205. Family.] THEOMBOLITE — EHLITE. 237 globule ; easily soluble in nitric acid or ammonia. Chem. com. 70*8 copper protoxide, 21 '2 phosphoric acid, and 8 water, but some arsenic acid, which occurs also in the other phosp. of copper. Eheinbreitenbach, Nischne-Tagilsk, and in Cornwall. Bihydrite, G. = 4*4 and 6 water, and Copper-diaspore, seem varieties. 282. Thrombolite.— Cu + 6 H. Porodine. Fracture conchoidal ; brittle. H. = 3...4; = 3'38...3'40. Opaque; vitreous. Emerald, leek, or dark green. B.B. colours the flame blue and then green ; on charcoal fuses easily. Chem. com. 45' 1 phosphoric acid, 37*8 copper protoxide, and 17*1 water. Eetzbanya. 283. LiBETHENITE. Cu^ P -f H. Ehombic ; ooP (u) 92° 20', Poo (o) 109° 52', and P . (Fig. 206). Cleavage, brachy diagonal and macrodiagonal imperfect. H. = 4; G. = 3-6. ..3-8. Translucent on the edges ; resinous. Leek, olive, or blackish green ; streak olive-green. B.B., and with acids, like phospho- rochalcite. Chem. com. 66 copper protoxide, 30 phosphoric acid, and 4 water. Libethen in Hungary, Tagilsk, and Gunnislake in Cornwall. 284. Tagilite.— Cu^ P4-3 H. Monoclinic but botryoidal, and radiating fibrous or earthy. H. = 3 j G. = 4*0. Emerald-green. Chem. com. 61*8 copper protoxide, 27*7 phosphoric acid, and 10*5 water. Nischne-Tagilsk, and near Hirschberg. 285. Ehlite.— Cu^ P + 3 H. Ehombic ; but botryoidal or reniform, and radiating foliated, or compact. Cleavage in one direction perfect. H. = 1-5. ..2 ; G. = 3-8. ..4-27. Translucent on the edges ; pearly on the cleavage. Verdigris-green ; streak paler. B.B. breaks violently into small fragments. Chem. com. 67 copper protoxide, 24 phosphoric acid, and 9 water. Ehl on the Ehine, Nischne-Tagilsk, and Libethen. Prasin is similar. Fig. 206. 238 AT AC AMITE — BROCIIANTITE. [Co2:>per Salts 286. Atacamite.— Cu CI + 3 Cu H. ' Ehombic; ooP (ilf) 112° 25^ Poo (P) 106° 10', and 00 Poo (A) "(Fig. 207); also reniform and columnar or gra- nular. Cleavage (h) perfect. H. = 3... 3'5 ; G. = 3'7...3'9, Semi transparent or translucent on the edges ; vitreous. Olive, grass, or emerald green ; streak apple- green. B.B. fuses, and leaves copper ; easily soluble in acids. Cliem. com. 55*85 copper protoxide, 14*86 copper, 16*61 chlorine, and 12*68 water; or 74*46 cop- per protoxide and 17*09 h. acid. Eemo- linos and Santa Eosa in Chili, Tarapaca in Bolivia, Schwarzenberg, Burra-Burra, Australia, and on the lavas of ^tna and Vesuvius. Used as an ore of copper. Fercylite, tesseral crystals, from Sonora, Mexico. Azure- blue. Contains chlorides of lead and copper, with oxides of lead and copper, and water. 287. VoLBORTHiTK— (Cu Ca)' V + H. Hexagonal; small tabular crystals, OP . ooP, single or in groups. H. 3 ; G. = 3*45... 3 '8 9. Olive-green ; streak almost yellow. B.B. on charcoal fuses easily, and forms a graphite-like slag, . containing grains of copper; on platina wire, with salt of phosphorus, forms a green glass ; soluble in nitric acids, and with water gives a brick-red precipitate. Chem. com. 37 to 38 vanadic acid, 39*4 to 46 copper oxide, 18*5 to 13 lime, 3*6 to 5 water. Syssersk, Nischne-Tagilsk, and Friedrichrode in Thuringia. 288. Brochantite.— Cu S + 3 Cu H. Ehombic; ooP 104° 32', Poo 152° 37', and (xPoo ; also reniform. Cleavage, brachydiagonal very perfect. H.' = 3*5. ..4; G. = 3*75. ..3*9. Transparent or translucent; vitreous. Emerald or blackish green ; streak briglit green. B.B. on charcoal fuses, leaving copper; easily soluble in acids. Chem. com. 70 copper protoxide, 18 sulphuric acid, and 12 water. Eezbanya, Katliariuenbni'g, and Eougliton Gill in Cumberland ; also Krisuvig in Iceland {Ivrisuvigite), Family.] LANGITE — ZEUNERITE. 239 289. Langite.— Cu S + 5 H. Ehombic ; ooP=123'' 44'. Crystals, long tabular, mostly in macles. Cleavage, basal and brachydiagonal. H. = 2*5; G. = 3*5. Vitreous. Greenish-blue. Easily soluble in acids and ammonia. Chem. com. 65 '1 copper protoxide, 16*4 sulphuric acid, and 18 '5 water. Cornwall. Warringtonite is similar ; also Konigine from Siberia. 290. Uranite, Lime-Uranite, \ i^^2^ ^ , g jj Autunite. Uran-Mica in part. J ^ ~r ^ ) -r Ehombic ; (xP = 90° 43', P middle edge 127° 32' ; thus nearly tetragonal, and crystals flat, tabular, and very like those of chalcolite. Cleavage, basal very perfect ; sectile. H. = 1...2; G. = 3...3-2. Translucent; pearly on OP. Siskin-green to sulphur-yellow ; streak yellow. B.B. on charcoal fuses to a black semicrystalline mass ; with soda forms a yellow infusible slag ; in n. acid forms a yellow solution. Chem. com. 15 '5 phosphoric acid, 62*6 uranium peroxide, 61 lime, and 15*8 water. Johann Georgenstadt and Eibenstock in Saxony, Autun and Limoges in France, Chesterfield in Massachusetts, and Cornwall. ^""vZ^e^' ^'^^'"1 (Cu+^J^)P+8 H. Tetragonal: P middle edge 142° 8', Poo 128° 14'. Crystals, OP . P (o, P) (Fig. 208), or with ooP. Cleavage, basal very perfect, and pearly lustre. Brittle. H. = 2,.. 2'5 ; G. = 3*5.. .3*6. Grass to emerald or g — verdigris green ; streak apple-green. B.B. rC j* p \ like uranite, but with soda yields a grain of — ^ copper. Chem. com. 15*2 phosphoric acid, 61 uranium peroxide, 8*5 copper protoxide, and 15*3 water. Johann-Georgenstadt, Eibenstock, Schneeberg, Bodenmais, near Baltimore, North America, and near Eedruth, and St. Austle. 292. Zeunerite.— (Cu' + As'+ 24 H. Tetragonal ; and in form, cleavage, colour, and H. like chalcolite. But G. = 3*2. Chem. com. 15*1 arsenic acid, 55*6 uranium peroxide, 8*7 copper protoxide, 14-5 water, 240 ERYTHEINE— ANNABERGITE. [Copper Salts with 5-2 iron peroxide, and 1'2 lime. Neustadtel, Schnee- berg. *293. Erythrine, Cobalt-Bloom.— Co' As + 8 H. Monoclinic; cxP^oo (P) . ooP^oo (T) . Poo (M) (like Fig. 195), with M: T=55' 9'; also ooP3 (k), and P (I) 118° 23' (Fig. 209). Cleavage, clinodia- gonal (P) very perfect; sectile; thin laminse flexible. H. = l-5,.,2-5 ; G. = 2'9...3-0. Translucent ; vitreous ; pearly on the cleav- age. Crimson or peach-blossom red. B.B. on charcoal fuses with arsenic fumes to a gray globule; colours borax blue; easily 1^ L-fy" ^^-^^^^^ (^^^) acids. Chem. com. 38*2 ( /V^/ arsenic acid, 37 '8 cobalt protoxide, 24 \l /Jy^ water ; but often with 0 to 8 lime, or the ^^^^^ protoxides of iron 1 to 4, and nickel 0 to 9. Schneeberg, Saalfeld, Allemont, Eiech- elsdorf, the Pyrenees, and Modum in Norway ; also Corn- wall, Alston in Cumberland, at Alva in Stirlingshire, and Tyndrum in Perthshire. Used in preparing blue colours. Kottigite, — White or peach-blossom red incrustations of minute crystals like erythrine, with which it agrees, but the cobalt almost wholly replaced by zinc. Schneeberg. KohaUheschlag, or Earthy-encrmting Cobalt, reniform, is a mixture of erythrine with arsenious acid. Lavendulan. — Thin reniform lavender-blue crusts ; trans- lucent ; resinous or vitreous. H. = 2'5..,3; Gr. = 2-95... 3*1. B.B. fuses very easily, colouring the outer flame blue. Consists of arsenic acid, protoxides of cobalt, nickel, and copper, with water. Annaberg. 294. Annabergite, Nickel-ochre. — Ni' As -|- 8 H. Monoclinic (?); in capillary crystals, also massive, earthy; rather sectile. H. = 2...2-5; G. -3...3-1. Dull or glis- tening. Apple-green or greenish-white; streak greenish- white and shining. B.B. on charcoal fuses with arsenical vapours ; easily soluble in acids. Chem. com. 387 arsenic acid, 37*3 nickel protoxide, and 24 Avatcr, but with a little cobalt or iron. Andreasberg, Annaberg, Saalfeld, Eiechels- sJi\ \^\k si^l Family.] EMERALD-NICKEL — CERUSSITE. 241 dorf, Joachimsthal, and Leadhills. Used in preparing blue colours. 295. Emerald-Nickel, Zaratite. — M C + 6 H. Amorphous, reniform, and encrusting. H. = 3 ; G. 2-6... 2-7. Translucent; vitreous. Emerald-green. B.B. infusible, becomes black and shows reaction for nickel. Effervesces and forms a green solution in acids. Chem. com. 59-3 nickel protoxide, 11*7 carbonic acid, and 29 water. On chromite at Swinaness, Unst, Texas in Penn- sylvania. Also Cape Ortegal, Spain, and Tyrol. Family IV. — Lead-Salts. Crystallisation predominantly rhombic and monoclinic in the lead compounds, but in some salts of other metals tetragonal or hexagonal. Hardness moderate, generally from 2... 4 -5, or about calc-spar. All have a high specific gravity, or from 5 -3.., 8,— this family including all minerals without metallic lustre and aspect, with Gr. above 5-5. They are all soluble in nitric acid, and form coloured solu- tions or precipitates. They are all easily fusible, and mostly readily reduced alone, or with soda, to lead. They are mostly compounds of lead, and the cerussite is an ore of this metal. The others are not abundant, but often show fine colours. Occur chiefly in veins and mines with other ores of lead. Lead B.B. on charcoal forms a greenish or sulphur- yellow coating round the assay. Solutions in nitric acid give, with sulphuric acid, a white precipitate, reduced B.B. ; and with chromate of potassa, a yellow precipitate. **296. Cerussite, Lead Spar.— Pb C = [Pb 0 . CO']. Ehombic ; isomorphous with arragonite and nitre ; ooP (M) 117° U; Po) 108° ly, 2Poo (u) 69° 18'; also OP, P (t), ^Pgc (s), (xPgo (/), a)P3 (e)(Figs. 210, 211). Macles are very common (Fig. 212); also granular or earthy. Cleavage, ooP and 2Poo rather distinct; fracture con- choidal; brittle and easily frangible. H. = 3...3-0 ; G. = 6-4... 6-6 (earthy 5-4). Transparent or translucent; ada- r 242 ANGLESITE. [Lead-salts mantine or resinous. Colourless and often white, but also gray, yellow, brown, black, rarely green, blue, or red; streak white. B.B. decrepitates violently, but easily fused and reduced ; soluble with effervescence in nitric acid. Fig. 210. Fig. 211. Fig. 212. Chem. com. 83*5 protoxide of lead and 16*5 carbonic acid. Very common at Przibram, Mies, and Bleistadt, Tarnowitz, Johann-Georgenstadt, Zellerfeld, Klausthal, Beeralston in Devonshire, St. Miniver's in Cornwall, Alston Moor, Kes- wick, Leadhills, and Wanlockhead, and many other places. *297. Anglesite.— Pb S = [Pb 0 . SO']. Ehom_bic; ooP 103° 43', Poo 75° 35'. The crystals of many forms and combinations, are short prismatic, or pyra- midal, or tabular; like Fig. 213 (but often placed in other positions). Cleavage, prismatic along ooP and basal, neither very perfect ; fracture conchoidal ; very brittle. H. = 3 ; y — r\ G. = 6'2...6'35. Transparent or translucent; adamantine or resinous. Colourless and white, but occasionally yellow, gray, brown, or blue ; streak white. Decrepitates in candle; B.B. on charcoal fuses in the ox. flame to a milk-white Fig. 213. ])ead ; very difficultly soluble in acids, wholly in solution of potash. Chem. com. 73*7 lead protoxide and 26*3 sulphuric acid, in some with a little silver. Zellerfeld, Claus- thal, Badenweiler, Siogen, Silesia, Linares, Phoenixville in Pennsylvania, l^iiys Miiu^ in Auglesea, St. Ives in Cornwall, Derbyshire, Leadhills, and Wanlockhead. Compact (Blei- (jlas), Alston Moor in Cumberland. Family?^ LEADHILLITE — CALEDONITE. 243 298. Leadhillite. — 3 Pb C + Pb S. Ehombic; P middle edge 137°, ooP 120° 20', 2Poo 43° 12'. Crystals, OP. goP . coPoo {c, m, a, Fig. 214), mostly tabular 3 also macles. Cleavage, basal very perfect ; slightly brittle. H. = 2*5; G. = 6*26 ... 6-44. Transparent or translucent; resinous or adamantine, pearly on OP. Yellowish-white, inclining to gray, green, f j ^ yellow, or brown. B.B. on charcoal intumesces, and becomes yellow, but again white when cold, and easily reduced ; soluble with effervescence in nitric acid, leaving sulphate of lead. Chem. com. 72*6 carbonate and 27*4 sulphate of lead. Leadhills, Taunton ; also Grenada and Nertschinsk. Maxite, found with it at Igle- sias, Sardinia, with 2 water, is probably the same. 299. SusANNiTE.— 3 Pb C + Pb S. Ehombohedral j R 72° 30'. Cleavage, basal perfect. H. = 2"5; G. = 6*55. White, green, yellow, or brown. Otherwise like leadhillite. Susannah Mine, Leadhills, Moldawa. According to Kenngott, may be only triple macles of leadhillite, but G. higher. 300. Lanarkite. — Pb "S + Pb C. Monoclinic; ooP (a) 49° 50' . OP : P'oo (h : c) 59° 15' (Fig. 215). Cleavage, basal very perfect; sectile, thin laminse flexible. H. = 2...2-5; G = 6*3. . .6*7. ^ \ Transparent ; resinous or adamantine ; on OP | X ^ pearly. Greenish or yellowish w^hite, inclin- x /^ \J ing to gray ; streak white. B.B. on char- coal fuses to a white globule containing metallic lead ; partially soluble in n. acid with effervescence. Chem. com. 53 sulphate and 47 carbonate of lead. Leadhills, rare. Pisani says is nearly pure Pb S, and no effervescence. 301. CALEDONITE.— 3 Pbjs -}- 2 Pb 0 -f Cu C. ^Rhombic; ooP 94° 47', Poo 109° 38'. Crystals OP . ooPoc . ccP (c, a, m, Fig. 216) (or Monoclinic, with a to c 90° 30', and a to m 132° 32", Schrauf). Cleavage, brachy- diagonal (a) distinct, two others (m, c) imperfect. H. = 2'5 .0.3 ; G. = 6'4. Transparent or translucent; resinous. Ver- digris to mountain green ; streak greenish- white. B.B. on 244 LINAKITE — MEXDIPITE. [Lead-salts charcoal easily reduced ; soluble in nitric acid, leaving ^ sulphate of lead. The solution is greenish, and shows reaction for lead and copper, j Chem. com. 55-8 sulphate of lead, 3 2 '8 car- bonate of lead, and 11 "4 carbonate of cop- Fio" 216 °' * per. Leadhills, Eed Gill in Cumberland, and Eezbanya. 302. LiNARiTE.— Pb S + Cu H. Monoclinic; C. = 77° 27', (xP 61° 36', 2P^cc 52" 38'. Crystals ocP'oo . OP, with the above or other forms ; macles united by ocP^'oc . Cleavage, orthodiagonal very perfect, basal less so ; fracture conchoidal. H. = 2-5...3 ; G. = 5'2 ...5'45. Translucent; adamantine. Azure-blue; streak pale-blue. Chem. com. 75*7 sulphate of lead, 19 "8 copper protoxide, and 4 '5 water. Leadhills, Eed Gill, Eoughten Gill, Linares, and Xertschinsk. Pb CI + Pb C. 303. Phosgenite, Corneous Lead, Cerasine. Tetragonal; P 113° 56\ Crystals short prismatic or sharp pjTamidal. Cleavage, ocP rather perfect; fracture conchoidal. H. = 2'5...3; G. = 6...6-2. Transparent or translucent ; resinous adamantine. White, yellow, green, or gray. B.B. fuses easily to an opaque yellow globule, crystalline on cooling ; soluble with effervescence in nitric acid. Chem. com. 51 chloride and 49 carbonate of lead. Very rare ; Matlock and Cromford, Derbyshire, and Stott- field near Elgin in Scotland ; Tarnowitz. 304. Mendipite, Berzelite.— Pb CI + 2 Pb. Ehombic ; but chiefly massive. Cleavage, along ooP 102° 36' highly perfect; fracture conchoidal or uneven. H. = 2*5. ..3 ; G. = 7"0...7*1. Translucent ; adamantine- pearly on the cleavage. Yellowisli-white to straw-yellow and pale-red ; streak white. B.B. decrepitates, fuses easily, and becomes more yellow ; easily soluble in nitric acid. Chem. com. 40 chloride and 60 protoxide of lead = 85-8 lead, and 9*8 chlorine. Churchill in the Mendip Hills, and Brilon in Westphalia. Family.] MATLOCKITE — MIMETESITE. 245 305. MATLOCKITE.— Pb CI + Pb. Tetragonal ; P 136° 17'. Crystals, OP . P . Poo , small, thin, tabular. Cleavage, basal indistinct ; fracture uneven conchoidal. H. = 2'5 ; G. = 7*21 (Greg.), 5*39 {Bam.) Transparent or translucent ; adamantine. Yellowish or greenish. B.B. decrepitates and fuses to a grayish-yellow globule. Chem. com. 55*6 chloride of lead, and 44-4: lead oxide. Cromford, on galena. 306. COTUNNITE, Cotunnia.— Pb Cl = [Pb CI']. Ehombic ; ooP 118° 38^ Poo 126° 44^ Small acicular crystals. Transparent ; adamantine. White. H. = 2 j G-. = 5*238. B.B. on charcoal fuses easily, colours the flame blue, volatilises, forms a white ring, and leaves a little lead. Chem. com. 74 lead and 26 chlorine. Crater of Vesuvius after the eruption of 1822. *307. Pyromorphite. I ^ ^ + ? ( = [3 (3PbO.F 0') + Pb CF]. Hexagonal; P 80° 44'. Crystals ooP . OP, with ooP2, or P (M, F, x) (Fig. 217), occasionally thicker in the middle, or spindle-shaped ; also reniform or botryoidal. Cleavage, P very imperfect, ooP in traces ; fracture conchoidal or uneven. H. = 3'5...4; G. = 6*9. ..7*0. Translucent j resinous or vitreous. Colourless, but generally grass, pis- tacio, olive, or siskin green, and clove or hair brown. B.B. fuses easily, with a transitory igni- tion, to a crystalline granule ; soluble in nitric acid and in solution of potash. Chem. com. 89*7 phosphate and 10*3 chloride of lead, but wdth 0 to 9 arseniate of lead, 0 to 1 1 phosphate of lime, and 0 to 1 fluoride of calcium. Przibram, Mies and Bleistadt in Bohemia, Zschopau, Clausthal, Poullaouen, Beresof, PhoBuixville in Pennsylvania, and Mexico; also Cornwall, Derbyshire, Yorkshire, Durham, Cumberland, Wicklow, Strontian, Leadhills, and Wanlockhead. Miesite, Polysphcerite, and Nussierite, from near Beaujeu, are varieties. *308. Mimetesite.— 3 Pb' As + Pb CI. Hexagonal ; P 81° 48^ Crystals, ooP . OP . P (Fig. 217), or P . OP. Cleavage, P rather distinct, ooP very imperfect ; 246 plombgom:me — ^yanadinite. [Lead-salts fracture conchoidal or uneven. H. = 3-5. ..4*0; G. = 7*19... 7 '25. Translucent. Colourless, but usually honey or wax yel- low, yellowish-green, or gray. B.B. on charcoal fusible, but less easily than pyromorphite, with strong arsenious vapours. Chem. com. 90'7 arseniate and 9*3 chloride of lead ; but part of the arsenic occasionally replaced by phosphoric acid. Johann-Georgenstadt, Zinnwald, Badenweiler, St. Prix in France, Xertschinsk, and Zacatecas in Mexico : Huel Alfred and Huel Unity in Cornwall, Eoughten Gill and Dry Gill, Cumberland ; Beeralston in Devonshire, and Leadhills. Karapyllte. — Orange-yellow ; G. = 6°8...6'9. Chem. com. like mimetesite, but contains phosphate of lime and chromate of lead. Alston in Cumberland and Badenweiler. Hediiijhane. — Crystalline masses with an imperfect hex- agonal cleavage. G. = 5'4...5'5. Translucent; resinous adamantine. White. Chem. com. like mimetesite, but 13 arseniate and 15 'o jAosphate of lime. Langbanshj-tta. 309. Plo:.ibgo3Die.— Pb' P + 6 Al ff. Eeniform or stalactitic. Fracture conchoidal and splin- tery. H. = 4...4'5; G. = 6*3. ..6-4. Translucent; resinous. Yellowish or greenish- white to reddish-brown. B.B. on charcoal becomes opaque and white, intumesces, and par- tially fuses ; soluble in nitric acid. Chem.com. 38 prot- oxide of lead, 35 alumina, 8 phosphoric acid, and 19 water ; but with 2 chloride of lead. Poilllaouen and Xussiere near Beaujeu. It much resembles gum-arabic. 310. Bleinierite. — Pb, Sb, iS. Eeniform, spheroidal ; earthy, or encrusting. H. = 4 ; G. = 3-9...1:"76. Opaque; dull resinous, or earthy. Gray, brown, red, or yellow ; streak grayish or yellowish white. B.B. on charcoal reduced with antimony fumes. Chem. com. mixture of protoxide of lead (40 to 62), antimony oxides (31 to 47), and water (G to 12); some also contain arsenic acid. Xertschinsk, Lostwithiel in Cornwall. 311. Vanadinite.— 3 Pb' Y + Pb CI. Hexagonal; P 78° 4G^ to 80°, like pyromorpliite. H. = 3- G. = G*S...7'2. Ojxaque ; resinous. Yellow and brown ; streak white. B.B. decrepitates violently, and on Family.'] DECHENITE — WULFENITE. ' 247 charcoal fuses to a globule, which emits sparks and is re- duced ; in nitric acid forms a yellow solution ; n. acid dropped on the crystals colours them first deep red, then bright yellow. Chem. com. 89*7 vanadiate, and 10*3 chloride of lead. Zimapan in Mexico, Beresof, and Wanlockhead. 312. Deghenite. — Pb Y. Ehombic; P middle edge 91°, but mostly botryoidal or thin lamellar. H. = 3'5...4: ; G-. = 5'81. Eesinous ; trans- lucent on the edges. Eed or reddish-yellow ; streak yellow. B.B. fuses easily to a yellow bead, and on charcoal reduced to lead; easily soluble in nitric acid. Chem. com. 54*7 lead oxide, and 45 '3 vanadic acid, but analysis gave 46 to 49 of the latter. Niederschlettenbach in Ehenish Bavaria. Kappel in Carinthia. Descloizite. — Small rhombic crystals ; olive-green to black j on fracture concentric yellow and brown zones. La Plata. Is probably identical. Similar are — Arceoxene ; botryoidal ; red, with a brown tinge. Chem. com. vanadic acid, with 48 '7 lead oxide, and 16"3 zinc oxide. Dahn on the Ehine. Eusynchite. — Yellowish-red ; opaque. B.B. melts easily to a lead-gray globule. Chem. com. 56 lead oxide, 23 vanadic acid, and 2 1 deutoxide of vanadium. Freiburg. Eosite. — Minute tetragonal crystals, aurora red, with brownish orange-yellow streak. Show reaction for moly- dena, vanadium, and lead. Leadhills. 313. Wulfenite. — Pbiiio. Tetragonal; P 131° 48'; OP (a), ^P {h), P, ooP, and Pgo (Fig. 2 1 8). Cleavage, P rather perfect, basal imperfect ; fracture conchoidal to un- even ; rather brittle. H. = 3; G. = 6-3. ..6-9. Pel- lucid ; resinous or ada- mantine. Colourless, but generally yellowish-gray, wax, honey, or orange yellow. B.B. decrepitates violently ; on charcoal fuses and sinks into the support, leaving lead ; in con. h. acid forms a yellow solution. Chem. com. 61*5 protoxide of lead and 3 8 '5 molybdic acid, but in some red 248 SCHEELITIXE— MELAXOCHEOITE. [Lead-salts varieties chrome preponderates. Bleiberg and Windisch Kappel, Eetzbanya, Badenweiler ; Plioenix\-ille in Pennsyl- vania, and Zacatecas. 314. ScHEELiTiNE, Stolzite.— Pb \Y. Tetragonal and hemihedric j P 131° 25'. Crystals, 2 P . P . ocP, spindle-shaped. Cleavage, P imperfect, h! = 3 • G. = 7-9,.. 8*1. Semitransparent or translucent: resinous. Gray, brown, yellow, or green. B.B. fuses to a dark crys- taUme gram, with salt of phosphorus in red. flame to a blue glass; soluble in nitric acid, with a yellow precipitate. Chem. com. 51-6 tungstic acid, and 48-4 protoxide of lead. Zinnwald ; Coquimbo ; and near Keswick. 315. Crocoisite, Krokoit. — Pb Cr. Monoclinic; C.= 77'27'; ocP 93° 42771/), P 119° 1'^ (0, ocP^2 (r) 56° lo; ^PV. {g) (Fig. 219). Cleavag-;, 00 P rather distinct; sectile. H. = 2-5. ..3; G. = 5-9...6-l. Trans- lucent j adamantine. Hyacinth or aurora red ; streak orange-yellow. B.B. decrepitates, blackens, and fuses on charcoal, the lower part being reduced ; with borax or salt of phosphorus in the ox. flame a green, in the red. flame a gray glass ; soluble in warm h. acid. Chem. com. 31 chromic acid, and 69 lead protoxide. Beresof, Mur- sinsk, and Xischne-Tagilsk in the Ural ; Congonhas do Campo in Brazil, Eezbanya, Moldawa, and Tarnowitz. Used as a pigment, but not permanent. 316. Melaxochroite, Phoenicochroite.— Pb' Cr'. Pthombic ; dimensions unknown. Cleavage imperfect. H. ==3...3*5; G. = 5.75. Transhicent on the edges; re- sinous or adamantine. Cochineal to hyacinth red"; streak brick-red. B.B. on charcoal fuses easily to a dark 'crystal- line m.ass ; in the red. flame yiekls lead ; soluble in li. acid. Chem. com. 23 chromic acid, and 77 protoxide of lead. Beresof. Family.] VAUQUELINITE — KERATE. 249 317. VAUQUELINITE.— Cu' "C/+ 2 Pb' Crl Monoclinic ; C. = 67° 15'. Crystals OP . - P . - P^oo (or P, f, h), always macled (Fig. 220), the faces of OP forming an angle of 134° 30'; also botryoidal or reni- ^„-p-^__^ form. H.=:2-5...3j G. = 5-5. ..5-8. Semi- "{/j^^^j. translucent or opaque ; resinous. Blackish or ^^^^f^^o dark olive-green ; streak siskin-green. B.B. on charcoal intumesces, froths up, and fuses to a dark-grey metallic globule surrounded by small grains of lead ; in nitric acid forms a dark-green solution with a yellow re- sidue. Chem. com. 6 1 lead protoxide, 1 1 copper protoxide, 28 chromic acid. Beresof, Congonhas do Campo. 318. BiSMUTHiTE.— Bi' + 4 H. Disseminated, investing, or acicular. Fracture conchoidal or uneven; very brittle. H. = 4...4*5; G. = 6*8 ... 6*91. Opaque; dull vitreous. Gray, yellow, or green. B.B. de- crepitates, fuses very readily, and is reduced with efferves- cence ; in h. acid it forms a deep-yellow solution. Chem. com. 90'1 bismuth oxide, 6*4 carbonic acid, and 3*5 water. Ullersreuth near Hirschberg, Schneeberg, and Johann- Georgenstadt ; also Chesterfield in S. Carolina, where like cerussite. Fucherite ; minute rhombic crystals, ooP . OP. Cleav- age, basal perfect. H. = 4 ; G. = 5*9... 6*0. Vitreous; reddish-brown or red ; streak yellow. B.B. decrepitates, fuses, and with soda yields bismuth. Easily soluble in acids. Chem. com. Bi V, with 17 bismuth oxide, and 28 vanadic acid. Schneeberg in Saxony. 319. Kerate, Hornsilver. — Ag CI. Tesseral ; chiefly ooOoo ; small or very small ; also mass- ive. Fracture conchoidal ; malleable and yields to the nail. H. = 1 . . . 1 -5 ; G. = 5 '5 . . . 5 "G. Translucent ; adaman- tine resinous ; gray, occasionally bluish or greenish. B.B. fuses very easily to a gray, brown, or black bead, which in the inner flame is reduced ; slightly affected by acids, and slowly soluble in ammonia. Chem. com. 7 5 silver and 25 chlorine, but with some (0 to 6) iron peroxide. Johann- Georgenstadt, Joachimsthal, Huelgoet, Kongsberg in Nor- way, Spain, and Cornwall ; now chiefly from Mexico and Peru. 250 CALOMEL — EMBOLITE. [Lead-salts Carbonate of Silver (Selbite), ash-gray, massive, very soft, effervescing in nitric acid, and B.B. easily reduced, seems a mixture. Wolfach in Baden, and Eeal de Catorce in Mexico (Plata azul), a rich silver ore. 320. Calomel.— Hg' 01 = [Hg CI]. Tetragonal; P 135° 50'. Crystals like Fig. 120 above, but very small; sectile. H. = 1...2; G. = 6-4...6'5 (arti- ficial 7*0). Translucent; adamantine. Grayish or yel- lowish-white. In the closed tube it sublimes as a white mass, and with soda yields mercury. B.B. on charcoal, when pure, wholly volatilises ; in nitric acid not soluble, in h. acid partially. Chem. com. 15 chlorine and 85 mercury. Moschellandsberg in Ehenish Bavaria, also Idria and Almaden. 321. lODITE. — Ag I. Hexagonal, but usually in thin flexible plates. Malle- able. H. = 1...1-5 ; G. = 5-5...5-7. Translucent; resinous or adamantine. Pearl-gray, greenish or orange yellow. B.B. on charcoal becomes red, fuses easily, colouring the flame purple-red, and leaves a grain of silver. Chem. com. 54 iodine and 46 silver. Albarradon in Zacatecas ; Arqueros in Chili, and Guadalajara in Spain. 322. CocciNiTE.— Hg I. Scarlet-red, easily fusible, and subliming ; said to occur at Casas Viejas in Mexico, and to be used as a pigment. Chem. com. probably 44*3 mercury and 557 iodine, like the artificial salt, which crystallises in tetragonal pyramids. 323. — Bromtte. — Ag Br. Tesseral; goOgo and 0. Crystals very small; also crystalline grains. H. = 1...2; G. = 5-8...6. Very splen- dent. Olive-green or yellow, with gray tarnish; streak siskin-green. B.B. very easily fusible ; scarcely afi'ected by acids. Chem. com. 57*5 silver and 42*5 bromine. San Onofre in the district of Plateros in Mexico {Plata vtrde), and used as an ore of silver. 324. Embolite.— 2 Ag Br-f 3 Ag CI. Tesseral; ooO-ite.— ie. Zn. AIn; (?e, Mn). Tesseral : ij an 1 0 . y: 0 : als o granular. Cleayage, octatedraL bur very imperfect : fracture conchoidal or un- even : brittle. R = 6 ... 6 5 : G. = 5 0. . .5 3. Opaque ; imperfect metallic lustre. Iron-black ; streak dark reddish- brown. B.B. infusible, but shines brightly and gives out sparks when strongly heated. On charcoal, with soda, a deposition of zinc ; soluble in L acid with strong extrica- tion of chlorine. Chem. com. 66 to 69 iron and 15 to 18 manganese peroxides (or in part protoxides), and 1C> : : '27 zinc oxide. Fra nk lin and Sterling in Xew Jersev. Byduite, from Sterling, X. J. : dark or yello ^ : Titreons; G. = .t o : contains 30 per cent alnini «330. H_E-_ir"z. S-^cularlroii.— rr = J- 0^". Hexa^ : i l i iiedral ; E 86'. Crystals rh rni- bohedric. : li :i i : Jar, of E. OE (Fig." 223 . . E . JE (or n, F, s), iRg. '224:). Mades witli . : and mostly intersecting. Cleavage, E and OE, but seldom distinct ; fracture conchoidal or uneven ; brittle. H. = 5 5 ...6'5 ; G. = 5 1...5 3. Opaque, or in very thin laminae translucent and deep blood-red. Metallic : iron-black to steel-gray, but often tarnished, also red ; streak cherry-red or reddish-brown. Some weak magnetic. B.B. in the red. flame black and magnetic ; slowly soluble in acLls. Chem. com. 70 iron and 30 oxygen, but some contain oxide of titanium, chrome, or silica. Specular Iron Ore, varieties with crystalline structure and high metallic lustre, includes micaceous iron, thin lamellar ; and red iron froth, finer or scaly. The Bed Hotmatite or Family.] IRITE — LIMONITE. 255 red iron ore, with inferior lustre, lower specific gravity (4-5. ..4-9), and hardness (3. ..5), and deeper blood-red or brownish-red colours ; comprises the fihrous red iron, reni- form, botryoidal, and stalactitic, often with an irregular concentric structure; the compact and oclirey iron ores more earthy or minute ; the reddle or red chalk, still more earthy, and used as a drawing material ; and the jaspery, columnar, and lenticular clay iron, mere impure varieties. Crystals, Elba, St. Gotthardt, Framont in the Vosges, Arendal, Langbanshytta, Tilkerode in the Harz, Altenberg, Capas in Brazil, Katherinenburg and Nischne-Tagilsk. Micaceous, Zorge in the Harz, Tincroft in Cornwall, Tavis- tock in Devonshire, Wales, Cumberland, and Birnam in Perthshire; also in Auvergne, on Vesuvius, -^tna, and Stromboli. The Bed Ecematite, the Harz, Ulverstone in Lancashire, St. Leonards near Edinburgh, near Ballater and Allerg in Aberdeenshire, Arndilly on the Spey, and many other parts of Britain. A most abundant ore of iron. Martite. — Tesseral, 0, 0 . ooO and 0 . ooOoo . H. = 6 ; G. = 4-6. ..5-33. Iron-black; streak reddish-brown. A pseudomorph after magnetite, or a dimorphous form of hematite. Brazil, Monroe in New York, Framont, and Auvergne. 33 L Irite.— (Ir, 6s, Fe) ir, Os, Cr). Tesseral ; 0 ; but in fine iron-black scales, with strong metallic lustre, which mark paper. G. = 6*506. Strongly magnetic. B.B. fused with nitre gives out the odour of osmium; insoluble in acids. Chem. com. 62*86 peroxide of iridium, 10*30 osmium protoxide, 12*50 iron protoxide, 13*7 chrome oxide. Ural, with platina. *'^332. LiMONiTE, Brown J 2 Fe -f 3 H = Iron Ore. ([2 Fe' 0\ 3 0]. Fine fibrous, in spherical, reniform, and stalactitic ma;Sses ; also compact and earthy. H. = 4'5...5*5 ; G. — 3*4 ...3*95. Opaque; lustre weak silky, glimmering, or dull. Colour brown, especially yellowish, clove, hair, and blackish- 256 gOtheite. [Oxidised Iron brown, also yellow and green ; streak yellowish-brown to ochre-yellow. In the closed tube yields water, and the powder becomes red. B.B. in the outer flame red on igni- tion ; in the inner flame thin splinters fuse to a black magnetic glass. Chem. com. 85 '6 peroxide of iron (=60 iron), and 14*4 water; but occasionally with silica, alumina, or phosphoric acid. Harz, Thuringia, Siegen near Bonn, Naussau, Styria, Carinthia, Pyrenees, Siberia, Brazil, and the United States ; in Britain in Cornwall, at Clifton near Bristol, Sandlodge in Zetland, and in many other places. A valuable ore of iron, the iron usually uniting hardness with tenacity. Stilpnosiderite, Lepidokrokite, and Yellow ochre seem partly this mineral, partly gotheite, or mixtures. Bog-Iron Ore is also a hydrated oxide of iron, with no de- finite composition, and often containing thirty to fifty per cent of impurities. Phosphoric acid to 11 per cent. Occurs chiefly in bogs, meadows, and lakes, as in North Germany, Sweden, and Britain ; especially the northern and western counties and islands of Scotland. Other deposits from springs contain two or three atoms water to one atom iron peroxide. ^333. Got™^^ } Fe H ^ [Fe^ 0^ . 0]. Ehombic; P wjth polar edges 121° 5' and 126° 18', ooP {g) 94° 53; ooP2 {d) 130° 40', Poo (&) 117° 30', with (xP(X) {M) and P (P), (Figs. 225,226); also columnar, fibrous. 22G. or scaly. Cleavage, bracliydiagoiial very perfect ; brittle. H. = 5...5.5; G. = 3'8...4'4. 02)a(]ue, or in fine lamella} Family. 1 ILMENITE. 257 translucent and hyacinth-red ; lustre adamantine or silky. Colour yellowish, reddish, or blackish-brown ; streak brown- ish or reddish yellow. In the closed tube the powder yields water, and becomes reddish-browm. B.B. in the ox. flame also brown ; in the red. flame black and magnetic ; diffi- cultly fusible; soluble in h. acid, often leaving a little silica. Chem. com. 90 peroxide of iron and 10 w^ater, with silica and manganese peroxide. Foliated, Eiserfeld near Siegen. Crystals, Lostwithiel in Cornwall, and Clifton near Bristol. Capillary, Przibram, Hiittenberg in Carinthia, and Norway. Compact, Saxony, the Pyrenees, Ural, North America, and many other localities. Often a pseudomorph from pyrite. Turgite, with 94*15 peroxide of iron and 5*85 water; compact reddish-brown ; G. = 3'54...3.74 ; Turginsk in the Ural ; is probably a mixture. ^334. Ilmenite, [Pe, ti, or Titanitic Iron, j [Fe 0 . Ti 0' -1- Fe' 0']—Rams, Hexagonal and rhombohedral, isomorphous with hsema- tite, but sometimes tetartohedral ; E 86° (85° 40' to 86° 10'). Crystals tabular or rhombohedral, of OR {a) and R, with - iR {e\ - 2 R {d\ and ^(aP 2 {h'\ (Fig. 227). Also in macles, granular or foliated, or in loose grains. Cleavage, basal more or less perfect, and rhombohedral R less distinct ; fracture conchoidal or uneven. H. = 5 ... 6 ; G. = 4-66. ..5. Opaque ; semimetallic. Iron- black, often inclining to brown, rarely to steel-gray ; streak black, or in some reddish-brown. Slightly or not at all magnetic. B.B. infusible alone, but with salt of phosphorus in the red. flame a red glass; soluble, but often with much difficulty in h. acid. Chem. com. peroxide of iron Avith 8 to 53 blue oxide of titanium. Umen mountains ; Gastein in Salzburg {Kihdelophan) ; Eger- sund in Norway; near Arendal (Hystatit) ; Menaccon in Cornwall (Menacconite) ; Bourg d'Oisans in Dauphin6 (Crich- tonite) ; Massachusetts {JVashingtonite). s 258 CASSITEPJTE. [Tin Ore Iserhie, or magnetic iron sand, in cubes, octahedrons, and dodecahedrons, generally with rounded edges or in loose grains; strongly roagnetic. In chemical action and comjDosition it resembles ilmenite, but is perhaps only mag- netite mixed with peroxide of titanium. Iserweise in Bohemia, the Eifel, Auyergne, near Eome and Xaples : also in Xorthern Germany, Canada, and Xew Zealand : Corn- wall, sands of the Don in Aberdeenshire, and Loch of Tristan in Zetland. F.i^iiLY II.— Tlx Ore. Crystallisation tetragonal, rhombic, or rarely monoclinic, with prismatic forms. Hardness 5-5... 6 '5 or 7. Grayity 3-4:. ..4-3 in the titanium compoimds: 4*6. ..8 in the remain- der. Mostly not soluble, or yery difficultly, in acids, and also B.B. yery difficultly or not fusible. Colours dark, as black, brown, or red. Lustre resinous, semimetallic, or adamantine. Occur chiefly in the older crystalline strata, or in granite and syenite. **335. CASSITEPJTE. Tin Ore.— Sn-[Sn 0"^. Tetragonal : P 87' 7', Px 67° 50'. Crystals ocP . P : :r,P (.7) . P (,■) . xPx (/). or with Px (P). (Fio-. 22$) : and also xP2 (/•), and 3P|- (z), (Fig. 229). ' Macles yery com- i ^ r r Fig. 228. Fig. 229. mon, combined by a face of Px , with the chief axes 112^ 10' (Figs. 230, 231); also granuhir or iibrous {wood tin), or in rounded fragments and grains (stream tin. FamUy.'] WOLFEAM. 259 Cleavage, prismatic along ocP and ooPoo , rather imperfect; brittle. H. = 6...7j G=6"8...7'0. Translucent or opaque ; adamantine or resinous.. AVhite, but usually gray, yellow, red, brown, and black ; streak white, light-gray^ or brown. B.B. in the forceps infusible 3 on charcoal, in the inner flame (more easily with soda), reduced to tin. Not aff'ected by acids. Chem. com. 78'6 tin and 21 '4 oxygen, but often mixed with peroxide of iron or manganese, tantalic acid, or silica. Cornwall, Bohemia, Saxony, Galicia in Spain, and Portugal ; also Silesia, the Haute Yienne in France, Green- land, Sweden, Eussia, Xorth and South America, Malacca, Banca, and Queensland, Australia. The only ore of tin. The produce of the British mines in 1871 was 16.272 tons ore, yielding about 10,000 tons tin, worth H million sterling, the average price being about £138 per ton. Iti the same year the Dutch mines produced 7500 tons. Stannite. — Compact, brittle ; H. = 6*75; G. = 3-5. Yel- lomsh- white to yellow. Chem. com. 36-5 tin oxide with silica and alumina. A mixture with quartz. Cornwall. *336. WoLFRMi.— (Fe, Mn) W - [FeO, MnO . AYO']. Monoclinic; C. = 89° 22'; (xP (r) 100° 37', -^PV (/) 61° 54', Foo {u) 68° 6', ooPoo {M\ (Fig. 232). Macles rather common, also columnar, laminar, or coarse granular. Cleavage, clinodiagonal very perfect ; orthodiagonal im- perfect ; fracture uneven. H. = 5...5-5; G. = 7-1...7'5. Opaque ; resinous, metallic-adamantine on the cleavage. Brownish- black j streak black (varieties with most iron) to Fig. 230. Fig. 231. 260 COLUMBITE. [Tin Ore Fig. 232. reddish-brown (most manganese). Sometimes weak mag- netic. B.B. on charcoal fuses to a magnetic globule covered with small crystals ; soluble in warm h. acid, leaving a yellow residue. Chem. com. 76 tungstic acid, 9 '5 to 20 protoxide of iron, and 4 to 15 prot- oxide of manganese, in some with a little lime or magnesia, in others 0'3 to 1*1 niobic acid. Altenberg, Geyer, Ehrenfriedersdorf, Schlaggen- wald, Zinnwald, the Harz ; East Pool, Carnbroe, and mines near Eed- ruth ; Eona in the Hebrides ; also the Ural, Ceylon, and North America. Used for preparing pigments and steel. Blumite, Megahasite, yellowish or clove brown. H. = 3*5, with 71*5 tungstic acid, 23'1 manganese protoxide, and 5'4 iron protoxide, from Schlaggenwald and Peru, is closely related. Also Ferberite, from Spain. 337. CoLUMBiTE, Xiobite.— (Fe, Mn) (5^b, Ta). Ehombic; P middle edge 83° 8', ocP 135° 40', 2 Poo 112° 26'. Tabular, or broad prismatic (Eig. 233 in other posi- tion). Macles with chief axes at 62° 40'; also foliated or granular. Cleavage, brachydiagonal very distinct, macro- diagonal less so, and basal imperfect. H. = 6 ; G. =^ 5-4... ^ , 6 '4. Opaque; m.etallic adamantine. Brownish or iron black ; streak reddish brown or black. B.B. infusible ; not affected by acids. Chem. com. 13 to 18 protoxide of iron, 3 to 7 protoxide of manganese, and 77 to 81 niobic acid (but 3 to 35 tantahc acid in some), with a little oxide of tin or copper. Middletown and Haddam in Connecticut, and Chesterfield in Massachusetts ; Eabenstein near Bod- enmais, and Ilmen Mountains in granite. Evigtok, Green- land, in cryolite. Columbite and tantalite are botli isomorphous mixtures of niobic and tantalic acids witli protoxide of iron (or man- ganese). The pure columbite would give 78'8 niobic acid, \y Fig. 233. Family.] SAMARSKITE — YTTROTANTALITE. 261 pure tantalite 86 tantalic acid. In both G. rises as the tantalic acid is more abundant ; but the columbite is the best crystallised and in the finest crystals. 338. Samarskite, Uranotantalite, Yttroilmenite. Ehombic ; isomorphous with columbite ; mostly in flat somewhat polygonal grains. Fracture conch oidal ; brittle. H. = 5*5; Gr. = 5*6... 5'75. Opaque; strong semi-metallic. Velvet-black j streak dark reddish-brown. B.B. fuses on the edges to a black glass. In the closed tube decrepitates, yields water, incandesces, and becomes brown. Soluble in h. acid with difficulty, but wholly, to a greenish fluid. Chem. com. 50 niobic acid, 12 iron (with some manganese) protoxide, 1 1 uranium oxide, 6 thorium oxide, 4 zirconia, and 16 yttria with lime and magnesia. Ilmen Mountains in miascite. 339. Tantalite.— Fe (Ta, Nb), or [Fe 0 . Ta' 0']. Ehombic; P with polar edges 126"" and 112° 30', middle 91° 42'. Cleavages all very indistinct; fracture conch oidal or uneven. H. = 6...6-5; G. = 6-1...8. Opaque; semimetallic, adamantine, or resinous. Iron-black ; streak cinnamon or cofi'ee brown. B.B. infusible ; scarcely aff'ected by acids. Chem. com. 76 to 42 tantalic acid, 7*5 to 40 niobic acid, 9 to 16 iron protoxide, and 1 to 6 manganese protoxide. But some 1 to 10 tin oxide. (Cassiterotantalite) also in union with iron (manganese) protoxide. Kimito and Tammela in Finnland ; Broddbo and Finbo near Fahlun, and Chanteloube near Limoges ; always in granite. Tapiolite from Tammela, black with bright lustre. G. = 7*17. ..7*37, has the same composition, but is tetra- gonal like rutile. P middle edge 84° 52'. 340. YTTROTANTALITE.— (Y, Ca, Fe, U)'(Ta,W, 5?b). In two varieties — (a) Black Y., Rhombic, in short prismatic or tabular crystals, also in grains and lamellae. Cleavage, brachy diagonal indistinct ; fracture conchoidal or uneven. Opaque, or in thin splinters translucent. Iron- black, semimetallic lustre, and greenish-gray streak. H. = 5-5 ; G. = 5*4. ..5-7. {h) Yellow Y., Amorphous, yellowish- brown, or yellow, often striped or spotted; resinous or vitreous ; streak white. G. = 5*46. ..5*88. Both varieties 262 EUXENITE — AESCHYNITE. [Tin Ore B.B. infusible, but become brown or yellow ] not affected by acids. Chem. com. 57 to 60 tantalic acid, 1 to 8 tungstic acid, 0 to 20 niobic acid, 20 to 38 yttria, 0*5 to 6 lime, 0-5 to 6 uranium peroxide, and 0*5 to 3 '5 iron peroxide. Ytterby, and near Fahlun. Hjelmite is very like Black Y. Azorite, minute, greenish or yellowish white tetragonal pyramids from the Azores, seems a tantalate of lime. The Brown Yttrotantalite is Fergusonite. 341. EuxENiTE.— Y, li, Ce, Ca (Sb, Ti). Monoclinicj also compact, with no trace of cleavage. Fracture imperfect conchoidal. H. = 6'5j G. = 4*6. ..4-9. Opaque ; thin splinters reddish-brown translucent ; metallic vitreous. Brownish-black; streak reddish-brown. B.B. infusible; not affected by acids. Chem. com. 18 to 38 niobic acid, 14 to 35 titanic acid, 13 to 29 yttria, 5 to 8 uranium protoxide, and 3 to 8 cerium protoxide, chiefly ; the water is not essential. Hitteroe and Arendal. 342. Fergusonite.— (Y, Er, Ce)' (N^b, Ta). Tetragonal and hemihedric ; P 128° 28'. Usual form pPf .P.l^Pf . OP {z, s, r, i, Fig. 234). Cleavage, traces along P ; fracture imperfect conchoidal ; brittle.^ H. -5-5...6; G. = 5-6. ..5-9. Trans- lucent in thin splinters; semimetallic. Brownish- black ; streak pale-brown. B.B. infusible. Chem. com. chiefly niobic acid and yttria, with erbia, also a little cerium protoxide, tin oxide, uranium Fig. 234. oxide, and iron protoxide. Cape Farewell in Greenland, Ytterby, and Eiesengebirge. Tyrite, hvown, resinous or semimetallic; H. = 6*5; G. = 5-13...5'36 ; Helle, near Arendal ; is similar or identical. 343. Aeschynite. ^ Ehombic; cxP (m) 128° 6', 2 Poo (x) 73° 10'. h/\ Crystals long prismatic (Fig. 235). Cleavage, traces ; i m fracture imperfect conclioidal. H. = 5...5-5; G. = ? j 4-9.. .5*1. Opaque; submetallic or resmous. Iron- k 7 black or brown; streak yellowish-brown. B.B. iV2'i5 ^^^^^^ becomes yellow or brown, but is in- fusible ; not soluble in h. acid, partially in con. s. acid. Chem. com. about 51 niobic and titanic acids with Family. '\ SPHENE. 263 thorium oxide (16) and cerium protoxide (18) chiefly, but also some lanthanium and didymium oxides, and other substances. Miask in the Ural. *344. Sphene, Titanite.— Ca Si' + Ca Til Monoclinic; C. = 85° 22'; ooP (/) 133° 52', JP^o) (^) 55° 21, P^oo {y) 34° 21', OP (P), ooP^oo (^), ooP«3 {M\ and -|P^2 (??.) 136° 12'. Crystals horizontal prismatic or tabular, or very often oblique prismatic (Figs. 236, 237). Macles frequent ; also granular or foliated. Cleavage, in many ^ooP ; in others P^oo (r) 113° 30', imperfect. H. = 5...5-5 ; Gr. = 3*4...3*6. Semitransparent or opaque; adamantine or often resinous. Brown, yellow, or green. B.B. fuses on the edges to a dark glass ; with salt of phosphorus in the red. flame reaction for titanic acid ; wholly soluble in s. acid, which forms sulphate of lime. Chem. com. 31*3 silica, 40*4 titanic acid, and 28*3 lime, with 0 to 5 iron protoxide in the brown varieties. Dauphin^ near Mont Blanc, St. Gotthard, Tyrol, Arendal, Sweden, Saxony, France, America, and the Ural ; also Lake Laach and Ve- suvius ; in Scotland, in Criff'ell, near King's House, Ben Nevis, Strontian, Loch Ness, Aberdeenshire, Fetlar and Burra in Zetland. Greenovite, flesh-red, from St. Marcel in Piedmont, with much protoxide of manganese, is not distinct. Schorlamite, tesseral, black shining; H. = 7...7-5; G. - 3-78. ..3-86 ; from Arkansas, is similar. Fig. 236. Fig. 237. 264 BIIOOKITE— EUTILE— ANATASE. [Tin Ore 345. Brookite. — Ti. ^Ehombic ; P (e) with polar edges 135° 37' and 101° 3'. 00 P 2 (m) 99° 50', cxPoo (h) (Fig. 238). (Monoclinic like Wolfram, Schmuf.) Cleavage macrodiagonal. H. = 5 ' 5 . . . 6 ; G. = 3 -8 6... 4*2. Opaque or translucent ; metallic adamantine. Yellowish, reddish, or hair brown ; streak yellowish-white. B.B. infusible ; with salt of phosphorus forms a brownish-yellow glass. Chem. com. titanic acid, with 1*4 to 4-5 percent peroxide of iron. Bourg d'Oisans, Chamouni, and Fig. 238 ^^^^ Amstag in the Canton Uri, Miask, Magnet Cove in Arkansas (Arkansite) ; Snowdon and Tremaddoc, in North Wales. **346. EuTiLE, Nigrine.— Ti. Tetragonal; P 84° 40', Poo 65° 35'. Crystals ooP . 00 Poo . P, and ooP 3 . P (A, c, Fig. 239). Macles very com- mon (like Fig. 231) with chief axes at 114° 26' ; also em- bedded or granular. Cleavage, ooP and ooPoo perfect. H. =6... 6*5; G. = 4'2...4-3. Translucent or opaque; f^yj\. metallic adamantine. Eeddish-brown to red, also yellowish and black {Nigrine) ; streak yel- lowish-brown. B.B. unchanged alone ; with borax in the ox. flame forms a greenish, in the red. flame a violet glass ; not afl'ected by acids. Fig 239 titanic acid, with 1-5 per cent * ■ or more peroxide of iron. Alps, Spain, St. Yrieux near Limoges, Norway, the Ural, Brazil, and North America ; Craig Cailleach near Killin, Ben-y-gloe and Crianiarich in Perthshire, Ballater in Aberdeenshire, Hills- wick and Burra in Zetland. Used in painting porcelain to produce a yellow colour. 347. Anatase, Octaedrite. — Ti. Tetragonal; P 136° 36'. Crystals P . OP (P, Fig. 240), or P . -J P. Cleavage, basal and P both perfect ; brittle. H. -5-5...6 ; G. = 3-8...3-93. Semitransparent or opaque ; metallic adamantine. Indigo-blue or almost black, red, yellow, or brown, rarely colourless; streak white. Family?^ POLYMIGNITE — MENGITE. 265 B.B. infusible ; only soluble in warm con. s. acid. Chem. com. titanic acid with a little peroxide of iron, or rarely tin oxide. The Alps, as Bourg d'Oisans, Dauphin6,Valois, and Salzburg; Hof in Bavaria, at Slidre in Norway, Ural, Minas Geraes in Brazil ; near Liskeard and Tintagel in Cornwall ; also at Tavistock and Tremaddoc. 348. POLYMIGNITE. Ehombic; P with polar edges 136° 28' and 116° 22', ooP 109° 46'. Crystals long prismatic, and vertically striated. Cleavage imperfect ; fracture conchoidal. H. = 6'5 ; G. = 4*8. Opaque ; semimetallic. Iron-black ; streak dark brown. B.B. infusible ; soluble in con. h. acid. Ana- lysis by Berzelius — 46-30 titanic acid, 14*14 zirconia, 12-20 iron peroxide, 2*70 manganese peroxide, 5 '00 cerium per- oxide, 11*50 yttria, 4*20 lime {= 96*04). Fredriksvarn. 349. PoLYCRASE.— 4 E Ti + E«b. Ehombic, six-sided tables, ccP 140°. Cleavage, not observable ; fracture conchoidal. H. = 5 . . . 6 ; G. = 5 *0 . . . 5*15. Opaque, or in very fine splinters translucent yel- lowish brown. Black ; streak grayish-brown. B.B. de- crepitates violently and incandesces, but is infusible ; imper- fectly soluble in warm h. acid, wholly in s. acid. Chem. com. 27 to 29 titanic acid, 20 to 25 niobic (4tantalic) acid, 23 to 24 yttria, 7 to 9 erbia, also 2*6 to 2*9 Ce, 7*7 to 5*6 U, 2*7 to 0-5 Fe, and 4 to 3 water. Hittero. 350. Perowskite. — Ca Ti. Tesseral; especially ooOoo, also 303 and many other forms. Cleavage hexahedral. H. = 5*5;G. = 4. Opaque, or translucent on the edges ; adamantine. Dark reddish- brown, also grayish or iron-black. B.B. infusible ; slightly affected by acids. Chem. com. 58*9 titanic acid, and 41*1 lime, with 2 to 5 iron protoxide. Slatoust, Kaiserstuhl. 351. Mengite, G, Rose,—¥Q,'^T,Tl Ehombic ; ooP 136° 20'. The crystals small, prismatic ; fracture uneven. H. = 5. ..5*5 ; G. = 5*48. Opaque ; semi- metallic. Iron-black ; streak chestnut-brown. B.B. infusible, but becomes magnetic ; almost wholly soluble in warm con. s. acid. Ilmen mountains. Mengite of Brooke is monazite. 266 PECHURANE— PYKOLUSITE. [Tin Ore 352. Pechurane, Pitcli-blende.— TJ ©. Tesseral ; 0 ; also granular, reniform, columnar, or lamellar. H. = 5...6; G. = Q'5 or 7' 9... 8. Opaque; im- perfect metallic or resinous. Grayish, greenish, or brown- ish-black ; streak greenish -black. B.B. infusible; not soluble in h. acid, but easily in warm n. acid. Chem. com. proto-peroxide of uranium, or 84*78 uranium, and 15'22 oxy- gen, but with lead, iron, arsenic, lime, magnesia, silica, and other impurities. Some contain vanadium, others also selenium {Gummierz, H. = 2-5...3). Johann-Georgenstadt, Marienberg, Annaberg, Przibram, Eezbanya, and near Eed- ruth in Cornwall. Used in porcelain-painting. Fittinerz, olive-green streak; H. = 3-0. ..3-5 ; G. = 4*8... 5-0 ; and Coracite, from Lake Superior, seem mixtures. Lie- Mgite, crystalline, concretionary, apple-green, and Foglite, bright green pearly scales, found on pechurane at Joachims- thal, are carbonates, the first of uranium protoxide and lime, the second also of copper protoxide, both with water. 353. Plattnerite. — Pb. Hexagonal; coP . OP . P. Cleavage indistinct; frac- ture uneven; brittle. G. = 9-39. ..9-44. Opaque ; metallic adamantine. Iron-black ; streak brown. Chem. com. 86*2 lead and 13*8 oxygen, with trace of sulphuric acid. Leadhills in Scotland. Family III. — Manganese Ores. Crystallisation rhombic, tetragonal, and monoclinic. Crystals often prismatic. H. = 1 ...7; G. = 2-3...5. Opaque; lustre more or less perfect metallic. Colour black or brown. B.B. infusible, mostly give out much oxygen, and do not become magnetic ; soluble in hydrochloric acid, with fumes of chlorine. The solution, saturated with carbonate of lime and filtered, gives, with chloride of lime, a copious dark- brown precipitate which acts like manganese oxide. Occur chiefiy in veins in tlie older rocks, often along with barytes. '^354. Pyrolusite. — Mn. Rhombic; coF (M) 93° 40'; Poo (d) 140°; oopoo (tv) and ooPgo (v). Crystals short, prismatic, or pointed (Fig. Family.'] POLIANITE — MANGANITE. 267 Fig. 241. 241); generally massive or reniform, and radiating, fibrous, earthy, or compact. Cleavage, ooP, also macro- and brachy- diagonal ; rather brittle or friable. H. = 2...2'5 ; G. = 4'7 ...5-0. Opaque; semimetallic or silky. Dark steel-gray, bluish, or iron-black ; streak black and soiling. B.B. infusible, loses oxygen^ and becomes brown ; soluble in h. acid, with large evolution of chlo- rine. Chem. com. 63 manganese and 37 oxygen. Ilmenau, Ihlefeld, Goslar, Johann-Georgenstadt ; also France, Hungary, Brazil, Cornwall, and Devon. Used for producing oxygen, chlorine, and chloride of lime, re- moving the brown and green tints in glass, in painting glass and enamel work, and for glazing and colouring pot- tery. Mostly a product of oxidation of polianite, man- ganite, and other manganese ores. Farvicite. — ^With 5 water, pseudomorphs after calc-spar ; also crystals with ooP = 99° 36', or columnar, and fibrous. G. = 4-5...4-6. Semimetallic. Iron-black to steel-gray; streak black. Warwickshire. 355. Polianite. — Mn. Ehombic; ooP 92° 52-; Poo 118°. Crystals like pyro- lusite, and vertically striated; also granular. Cleavage, brachydiagonal perfect. H. = 6*5...7; G. = 4*84. ..4*88. Weak metaUic. Light steel-gray. Chem. com. identical with pyrolusite, which thus a less hard variety. Platten, Schneeberg, Johann-Georgenstadt, and Cornwall. 356. MANGANITE.— Mn + H, or [Mn 0' -f ff 0]. Ehombic, sometimes hemihedric ; ooP (M) 99° 40', (xP2 (0 n8° 44',_Poo 114° 19'; also P3 (g\ ooP2 (r) 2P (m), and 2P2 (n), (Fig. 242). Crystals pris- matic, vertically striated, and in bundles ; also columnar or fibrous. Macles common. Cleavage, brachydiagonal very perfect, basal and ooP less perfect ; rather brittle. H. = 3.5...4; G. = 4-3. ..4-4. Opaque; imperfect metallic. Dark steel-gray to iron-black, or often brownish-black and tar- Mi Fig. 242, 268 HAUSMANNITE — PSILOMELANE. [Manganese Ores nished ; streak brown. B.B. infusible; soluble in warm con. h. acid. Chem. com. 89-9 manganese peroxide and lO'l water. Ihlefeld, in the Harz, Thuringia, Christiansand in Norway, Undenaes in Sweden, Nova Scotia, and Danestown near Aberdeen. 357. HAUSMANNITE. — Mn + Mn, or Mn^ Mn. Tetragonal; P 116° 5 9^ Poo 98° 32\ Crystals P or P . -i-P. Macles common (Fig. 243); also granular. Cleavage, basal rather perfect, less distinct P and Poo ; fracture uneven. H. = 5*5 ; G. = 4*7...4'8. Opaque; strong metal- lic ; Iron-black ; streak brown. B.B. like peroxide of mangan- ese ; soluble in h. acid, with escape of chlorine ; powder colours con. s. acid bright red in a short time. Chem. com. 31 protoxide and 69 peroxide of man- ganese, or 72 manganese and 28 oxygen. Ihlefeld, II- menau, and in Sweden. 358. Braunite.— Mn, or [3 Mn' O'+MnO.SiO^ Bams.] Tetragonal; P 108° 39'; hence almost an octahedron. Crystals P and P . OP. Cleavage, P rather perfect ; brittle. H. = 6...6*5; G. = 4-7. ..4-9. Imperfect metallic. Colour and streak dark brownish-black. B.B., and with acids like manganite. Chem. com. 70 manganese and 30 oxygen, but some 7 to 15 sihca. Elgersburg, Oehrenstock, Ihlefeld, and St. Marcel. 359. PsiLOMELANE.— (Mn, Ba, K, Cu) Mn' + H. Massive, botryoidal, or stalactitic. Fracture conchoidal or uneven. H. =:5'5...6; G. = 4*1. ..4-3. Dull or glim- mering. Iron-black or bluish-black ; streak brownish-black and glistening. B.B. infusible. Chem. com. 4*7 to 11 protoxide of manganese, 80 hyperoxide (but 20 to 50 mixed), 6 to 16 baryta, 2 to 5 potash, 0 to 1 copper, and 0*5 cobalt protoxide ; and tlms a mixture. Sclmeeberg, Ilmenau, France, Vermont, Cornwall, and Devon. Family.] CREDNERITE — WAD. 269 360. Crednerite. — Cu Mn'. Granular, foliated. Cleavage, very distinct along one face of an oblique rhombic prism, less so two others. H. = 4'o...5; G. = 4-9...5'05. Iron-black; streak brownish- black. B.B. very thin foliae scarce fusible on the edges ; with salt of phosphorus in the inner flame forms a glass, first green, then, copper-red; in h. acid it forms a green solution. Chem. com. -iS'S copper protoxide and 56 7 per- oxide of manganese. Friedrichsrode in Thuringia. 361. Cupreous Manganese. — (Mn, Cu) Mn' + 2 H. Amorphous ; botryoidal, stalactitic, or earthy. Eather brittle or friable. H. = 3-5 or less ; G. = 3'1 . ..3 2. Vitre- ous. Black, inclining to brown or blue ; streak similar. B.B. fusible, and yields copper. Contains 16 to 17 copper protoxide and 55 oxides of manganese, 15 to 18 water, with baryta, lime, protoxide of cobalt, and other substances ; thus scarcely a true species. Silesia, Saxony, the Harz, and Cornwall. Black copper, with 29-5 water and 30 manganese, 11 "5 copper and 28 iron peroxide, is similar. Harz. 362. KiRTHY Cobalt.— (Co, Cu) Mn + 4 H. Amorphous; reniform, sectile. H. = 1...1'5 ; G. = 2*1 2*2. Bluish or brownish black ; streak black, shining, and leaves a mark. B.B. infasible. Contains about 20 cobalt protoxide, 4-5 copper protoxide, and 21 water. Saalfeld, Gliicksbrun, Riechelsdorf, and Alderley Edge in Cheshire. Eorn-cohalt, Siegen, is a mixture with quartz. *363. ^Yad.— Mn (Ca, Ba, K) Mn + 3 H. Massive ; reniform, stalactitic, or froth-like ; also scaly, earthy, or compact. Very soft and sectile (rarely brittle, and H. = 3) ; G. = 2-3... 37 ; or porous, and swims on water. Semimetallic, and shining or dull. Colour and streak brown or black. B.B. like peroxide of manganese ; soluble in h. acid. Chem. com. very uncertain. Saxony, Harz, France, Devonshire, and Cornwall. GroroUife is a variety, and Neivkirkite related. 270 COBALT-OCHEE- ; — UEAXirM-OCHEE. [Ochres. OCHEES. The following sulDstances, chiefly products of decomposi- tion, and all compact, earthy, or disseminated, and scarcely true mineral species, may be described here : — 364. CoBALT-ocHEE, Earthy Cobalt.— Fe. As, Co, Ca, H. H. = 1...2; G. = 2...2"65. YelloT\'ish-gray or brown to liver-brown ; streak brown or yello^vish-gray and shining. In the closed tube yields water. B.B. emits odour of arsenic, and fuses to a black magnetic slag. Saalfeld, Pde- chelsdorf, Dauphine, and other localities. ' 365. MOLYBDEXA-OCHEE. Mo. Opacjue j dull. Straw, sulphur, or orange yellow. B.B. fuses and smokes ; soluble in h. acid. Sweden, Xorway, the Tyrol, and on Corybuy near Loch Creran in Scotland. 366. BlSMUTH-OCHEE. — Bi. Very soft and friable. G. = 4-36...4"7. Opacjue : dull, or glimmering. Straw-yelloAv to light-gray or green. B.B. fusible and easily reduced ; easily soluble in nitric acid. Schneeberg, Siberia, and St. Agnes in Cornwall. 367. AXTBIOXY-OCHEE. — Sb, H. Soft and friable. G. = 3'7...3'8. Opaque: dull or glimmering, with glistening streak. Yellow, yellowish-gray, or white. B.B. easily reduced. Harz, Hungary, Saxony, France, Spain, and Pad stow in England. 368. Stiblite.— Sb "Sb, H. Granular or compact. H. = 5*5 : G. = 5-28. Eesinous or dull. Yellowish-white or yellow. B.B. not reduced alone, but easily with soda. Chem. com. 75 antimony, 20'5 oxygen, and 5*5 water. Kremnitz, Felsobanya, and Mexico. 369. Tungsten-ochee. — AV. Soft. Earthy; dull. Yellow or yellowish-green. Soluble in caustic ammonia. Huntington, Connecticut. 370. Uranium-ociike. — ^J, H. Sectile, soft, and friabU\ Opaque ; dull. Straw, sul- phur, or orange yellow. In the closed tube yields water, Ochres.] MINIUM — CUPEITE. 271 and becomes red. B.B. in the red. flame becomes green, but does not fuse; easily soluble in acids. Joachimstlial, Johann-G-eorgenstadt, and St. Symphorien in France. 371. Minium (Native).— Pb + 2 Pb. Massive or earthy. H. = 2 . . . 3 ; G-. = 4'6 . Dull resinous. Aurora-red ; streak orange-yellow. B.B. fuses easily, and reduced; in h. acid loses its colour, and changed into chloride of lead. Chem. com. 90*7 lead and 9 '3 oxygen. Schlangenberg in Siberia, Badenweiler, Anglesea, Grassing- ton Moor and Weirdale in Yorkshire. 372. Lead-ochre. — Pb. G. = 8*0. Opaque ; dull. Sulphur or lemon yellow. Popocatepetl in Mexico. 373. Chrome-ochre.— Or. Opaque, or translucent on the edges ; dull. Grass- green to siskin or yellowish green. B.B. infusible ; soluble to a green fluid in solution of potash. Unst in Zetland, Creuzat in France, and Sweden. TVolchonskoite, emerald or blackish green, from Okhansk in Perm, is similar. 374. Tellurite. — Te. Spherical, and radiated fibrous. Yellowish or grayish white. SiebenbtLrg. Family IV. — The Eed Copper Ores. Tesseral and hexagonal. H. = 3*5.. .4*5 ; G. = 5*4. ..6. Translucent ; metallic. Eed or dark-gray. Soluble in acids, and B.B. fusible, except zincite. Are oxides of copper or zinc. *375. Cuprite, Eed Copper Ore.— eu=:[Cu 0]. Tesseral; 0, ooO, and ooOoo ; granular or compact. Cleavage, octahedral rather perfect; brittle. H. = 3'5...4; G = 5 '7 . . . 6 '0 . Translucent or opaque ; metallic-adaman- tine. Cochineal to brick red, with a lead-gray tarnish ; or crimson in transmitted light ; streak brownish-red. B.B. on charcoal becomes black, fuses, and reduced ; soluble in acids and ammonia. Chem. com. 88*9 copper and 11 '1 oxygen. Siberia, the Bannat, Chessy near Lyons, Linares 272 CHALCOTRICHITE— VALENTINITE. [Red Copper in Spain, Ural, South Africa ; and in the Huel Gorland, Huel Muttrel, Carvath, and United Mines in Cornwall. Valuable copper ore. 376. CHALCOTRICHITE. Ehombic or tesseral in fine capillary crystals (prisms or cubes). Cochineal and crimson red. In other characters like cuprite. Eheinbreitenbach, Moldawa, and Huel Gor- land, Carharrack, and St. Day in Cornwall. Tile-ore. — Eeddish-brown, or brick-red and earthy. Chem. com. suboxide of copper, mixed with much peroxide of iron and other substances. Bannat, Thuringia, Cornwall, and Shropshire. 377. Tenorite. — Cu. Ehombic, in thin tables ; also fine scaly or earthy. Translucent and brown ; metallic. Dark steel-gray or black. On lava, Vesuvius. 378. Melaconite. — Cu. Tesseral ; ooOqo . 0; also compact. H. = 3. ..4; G. = 6 ...6*3. Steel-gray or black. B.B. infusible in ox. flame ; soluble in acids. Chem. com. copper protoxide, in some a little iron peroxide or silica. Near Lake Superior. Maske- lyne describes melaconite from Cornwall as monoclinic with C. = 80° 28'. Copper protoxide would thus seem trimor- phous. 379. ZiNCiTE, Eed Zinc. — Zn. Hexagonal ; granular or foliated. Cleavage, basal and ooP very perfect. H. = 4. ..4*5 ; G. = 5'4...5-5. Translu- cent on the edges ; adamantine. Blood or hyacinth red ; streak orange-yellow. B.B. infusible, but phosphoresces. Chem. com. 80 ''2 6 zinc and 19 '7 4 oxygen, but with 3 to 12 manganese peroxide. Franklin and Sterling in New Jersey. Ore of zinc. Family V. — The White Antimony Ores. 380. Valentinite, White Antimony.— Sb, or [Sb' 0']. Eliombic; ooP 137°, Boo 70|°. Crystals oo Poo . ocP . Poo (7)f, A, Fig. 244) ; broad prismatic, or long tabular; Ores Family^ SENAEMONTITE — . -AESENITE. 273 Fig. 244. also granular, columnar, or foliated. Cleavage, ooP very perfect, brachy diagonal imperfect. H. = 2*5...3; G. =:5'5 ...5*6. Translucent; adamantine or pearly. Yellowish and grayish- white, brown, gray, and . rarely peach-blossom red ; streak white. B.B. ^ becomes yellow, and fuses (in the flame of a candle) to a white mass. In the closed tube wholly sublimes ; on charcoal forms a thick white coating ; easily soluble in h. acid ; the solution yields with water a white precipitate. Chem. com. 83*6 antimony and 16*4 oxygen. Przibram, Braunsdorf in Saxony, Harz, Hungary, AUemont in Dau- phin 6, and Siberia. 381. Senarmontite. — ^h. Tesseral ; 0 ; also massive. Cleavage, 0 imperfect. H. = 2...2-5; C = 5-2...5'3. Transparent to translucent; brilliant resinous or adamantine. White or gray. B.B. and chem. com. like valentinite. Sensa, near Constantine in Algeria, Perneck in Hungary, South Ham in Canada. 382. Cervantite. — Sb '^h. Acicular or incrusting. G. ==4'1. Eesinous. Yellow or white. B.B. infusible, but reduced on charcoal ; soluble in h. acid. Chem. com. 79*5 antimony, 20*5 oxygen. Cervantes in Spain, Auvergne, Hungary, and Pereta in Tuscany. 383. Arsenite. — As. Tesseral ; 0 (but also rhombic in smelting processes) ; usually capillary, flaky, or pulverulent. Cleavage octahe- dral. ^H. = 1-5 (3, Breit.) ; G. = 3-69. ..3-72. Translucent; vitreous. Colourless and white. Taste sweetish astringent ; highly poisonous. B.B. in closed tube sublimes in small octahedrons ; on charcoal volatilises with strong smell of garlic. Chem. com. arsenious acid, with 75*76 arsenic and 24*24 oxygen. Andreasberg, Joachimsthal, Kapnik, Alsace, and Pyrenees. The capillary varieties are probably rhom- bic, like the artificial, and the substance dimorphous. T 274 PLATINA. [Native Metals Order V. NATIVE METALS Form two groups or families. The first or Electropositive group — including platina, palladium, iridium, gold, silver, mercury, lead, tin, copper, and iron — have crystallisation tesseral, mostly in regular octahedrons or cubes. Some of them — as platina, palladium, iridium, and iron — are infusible B.B., gold, silver, and others easily fusible, and mercury fluid at ordinary temperatures. The second or Electro- negative group — including antimony, arsenic, osmium, tellurium, zinc, and bismuth — have crystallisation hex- agonal or rhombohedral, with E = 86° to 88° (thus almost an octahedron); they are easily fusible and burn and fume. Metals range in H. from mercury (fluid) = 0 and lead = 1*5 to iridium 6... 7 ; in G. from arsenic = 5 '7 to iridium = 23*0. They are all opaque, have metallic lustre and pure metallic colours (not lead-gray nor black) ; streak similar and shining. Are simple metals or alloys — that is, combi- nations of metals, as isomorphous elements in indefinite proportion. *384. Platina.— Pt, Fe. Tesseral ; very rarely in small cubes, commonly in minute, flat, or obtuse grains and roundish lumps. Cleav- age wanting ; fracture hackly ; malleable and ductile. H. = 4. ..5; G. = 17...19 (hammered 21-23). Steel-gray, in- clining to silver-white. Some shghtly magnetic (from iron). Very difficultly or not fusible ; in nitrochloric acid forms a red coloured solution. Cliem. com. platina, but always alloyed with 4 to 13 iron, 1 to 5 iridium, osmium, rhodium, palladium, or other metals. Found in diluvial deposits from serpentine in Columbia, Brazil, and St. Domingo ; in the Ural ; also in California, Canada, Borneo, the Harz, and France. The largest mass from South America weighs Family.] PALLADIUM — IRIDIUM. 275 1 lb. 9-^- oz. ; from the Ural, 18^ lb. English avoirdupois. Its hardness, infusibility, power of resisting acids, and other properties, render platina a very important material for chemical, mathematical, and philosophical instruments. In Eussia also used for money. Flatiniridium, Brazil, in minute silver-white grains, G-. = 16*94, contains 55*44 platina, 27*79 iridium, 6*86 rhodium, 4*14 iron, 3*30 copper, and 0*49 palladium. 385. Palladium. — Pd. Tesseral ; in very minute octahedrons ; mostly small grains or scales. Malleable. H. = 4*5...5; G. = 1 1*8. ..12*2. Light steel-gray or silvery-white. B.B. infusible ; in nitric acid forms slowly a brownish-red solution. Chem. com. palladium, alloyed with platinum and iridium. Brazil, in gold sands ; Tilkerode in the Harz, in very small, brilliant, hexagonal tables ; — hence rhombohedric and dimorphous. Used for astronomical and other instruments. 386. OsMiUM-iRiDiUM. — Ir, Os. (a.) Light Osmium-iridium or Newjanshite. — Hexagonal ; P 124°j OP . P . ooP (Fig. 245), more com- mon in small flat grains. Cleavage, basal rather perfect. Slightly malleable. Tin- white. H.=:7; G. = 19*38. ..19*47. B.B. not altered. Not affected by acids. Analy- sis, 46*77 iridium, 49*34 osmium, 3*15 rhodium, 0*74 iron, and trace of palladium. Newjansk in Ural, Brazil. [h.) Dark Osmium-iridium — -Iridosmium or Sisserkite. — PJiombohedral ; E = 84° 28 Lead-gray. H. = 7 ; G.= 21*118 (G. Rose). B.B. on charcoal becomes black, with a very strong odour of osmium ; in the flame of a spirit- lamp shines brightly and colours it yellowish-red. In one variety Berzelius found 25 iridium and 75 osmium, or Ir Os'; in another, 20 iridium and 80 osmium, or Ir Os\ Nischne-Tagilsk in Ural, Brazil, and California. Used for pointing gold pens. 387. Iridium.— Ir, Pt. Tesseral ; ooOoo . 0 ; also small rounded grains. Cleav- age, traces ; slightly malleable. H. = 6 . , . 7 ; G. = 2 1 '57 . . . 276 GOLD — SILVER. [Xo.tive Metals 2 3 "46. Silver- white, inclinirig to yellow on the surface. B.B. unalterable ; insoluble in acids, even the nitrochloric. Chem. com., by Svanberg's analysis, 76"S0 iridium, 19 '64 platina, 0"89 palladium, and TTS copper. Xischne-Tagilsk and Xewjansk. Used in porcelain-paintmg. **388. Gold.— Au. Tesseral; 0, ocOx, ocO, 303, ^02, and other forms. Crystals small, often elongated, deformed, and indistinct : also capillary, wire-like, arborescent, and in plates and grains. Eemarkably ductile and malleable. H. = 2'5... 3*0; G. = 1 7'0. . .19"4. Gold-yellow to brass or bronze yellow. B.B. easily fusible ; soluble in aqua regia, often with a precipitate of chloride of silver. The solution is yellow, and colours the skin deep purple-red. Cliem. com. gold with silver to 38 per cent, and copper and iron under 1 per cent. In beds and veins, often with Cjuartz. and in alluvial deposits in many parts of the world, — the Ural, Brazil, California, Australia ; in the sand of many rivers, as the Ehine and Tagus ; in Britain in many of the Cornish stream-works : in mineral lodes near Dolgelly, Xorth AVales ; in Scotland at Leadhills, Tyndrum, and Glen Coich, Perthshire ; and in Ireland in AVicklow. Australia yields above five millions sterling of gold annually ; the United States (California. Xevada, etc.) about fifteen millions : and whole earth probably over twenty- two millions sterling. Eledrum or alloys of gold and silver occur in all propor- tions, with colour ranging from purest gold -yellow to brightest silver-white, and G. from 19-0 to KVO. It has been proposed to limit the name to those with at least 15 per cent silver, and not less than 38 per cent gold. Fo7-pezite, from Porpez in Brazil, contains 10 palladinm and 4 silver ; lihodium-gold, from Mexico, 34 to 43 rhodium, and G. = 15-5...1G-8. *389. Silver.— Ag. Tesseral; cubes and octaliedrons ; also ccQ, 303, and oc02. Crystals small and often misshapen ; also capillary, filiform, arborescent, or tooth-like, and in leaves, plates, or Family.] MEKCUEY — AMALGAM— LEAD. 277 crusts. Malleable and ductile. H. = 2-5...3; G-. = lO'l ...iri. Silver- white, but often tarnished yellow, red, brown, or black. B.B. easily fusible; easily soluble in nitric acid; the solution colours the skin black. Chem. com. silver, often with copper, iron, gold (28 per cent), platina, antimony, and arsenic. Chiefly in veins, as at Andreasberg, Freiberg, Johann-Georgenstadt, and Kongs- berg in Norway (one mass 7 1 cwts.) ; Lake Superior ; Nevada, Mexico and Peru ; St. Mewan, St. Stephens, Huel Mexico, and Herland in Cornwall ; and at Alva in Stirlingshire. Britain produced 761,490 ounces silver, worth £190,000, in 1871, chiefly from lead ores. The annual produce of silver in the whole world, from all sources, is about eight to ten millions sterling. 390. Mercury, Native Quicksilver. — Hg. Fluid ; but at - 40° congeals, and forms tesseral crys- tals, a = 13-596 fluid, 15 '6 12 solid. Bright metallic; tin-white. B.B. wholly volatile, or leaves a little silver. Chem. com. mercury, sometimes with a little silver. Idria, Almaden, Wolfstein, and Morsfeld on the Ehine, the Harz, Peru, China, and California. 391. Amalgam. — Ag Hg^ and Ag Hg^ Tesseral; ooO, with 202, 0, (xOo) , 30f, and oo03 ; also compact, or in crusts and plates. Cleavage, traces along ooO; rather brittle. H. = 3...3-5; G. = 13-7...14-L Silver-white, and leaves the same colour on copper. In the closed tube yields mercury and leaves silver ; easily soluble in nitric acid. Chem. com. 35 and 2 6 '5 per cent silver; but varieties with more silver at Kongsberg 86*3 and 95*1 occur. Morsfeld and Moschellandsberg, Hungary, Sala, Allemont, and Almaden. Arquerite in small octahedrons or arborescent; ductile and malleable. H. = 2...2-5; G. = 10-8. Chem. com. 86*5 silver. Forms the chief ore in the rich silver mines of Arqueros near Coquimbo. Gold- Amalgam with 39 gold, occurs in Columbia and California. 392. Lead. — Pb. Tesseral, but only capillary, filiform, or in thin plates. Ductile and malleable. H. -1-5; G. = 11-36. ..11-40. 278 TIN — COPPER — lEON. [Native Metals Bluish-gray, with a blackish tarnish. B.B. very easily fusible ; on charcoal volatilises and forms a sulphur-yellow coating soluble in nitric acid. Said at Alston Moor, also near Kenmare in Ireland ; in the gold sands of Olahpian, the Ural, and Altai ; in dolomite at Pajsberg and Nord- mark ; in Mexico ; and in meteoric iron from Chili. 393. TiN.~Sn. This metal has not certainly been found native, though quoted from Cornwall and Miask. The fused metal crys- tallises in regular octahedrons. That formed by galvanic action is described as tetragonal, with P 57° 13'. *394. Copper.— Cu. Tesseral ; 0, ooOoo, ooO, oo02. Crystals small, and generally irregular and deformed. Macles united by a face of 0. Often filiform and arborescent, or in plates and laminae. Malleable and ductile. H. = 2 '5 . . . 3 ; G. = 8 '5 . . . 8*9. Copper-red, with yellow or • brown tarnish. B.B. rather easily fusible, colouring the flame green ; readily soluble in nitric acid. In large masses (one measured 65 feet long, 32 broad, and 4 to 7 thick), near Lake Superior, with native silver. Cornwall, near Eedruth and the Lizard ; Yell in Zetland, Chessy near Lyons, the Bannat, and Hungary ; Faroe Islands, Siberia, China, Canada, Mexico, Brazil, Chili, and near Ballarat, Victoria. *395. Iron.— Fe. Tesseral ; chiefly the octahedron. Cleavage hexahedral, but often mere traces ; fracture hackly ; malleable and ductile. H. = 4-5; G. = 7-0. ..7*8. Steel-gray or iron- black, often with a blackish tarnish. Very magnetic. B.B. infusible, or only in thin plates with a strong heat ; soluble in h. acid. Two varieties are distinguished : — (a.) Telluric Iron. — Li grains and plates, or disseminated. Almost pure iron, or contains carbon, graphite, lead or copper, but not nickel. Mulhausen in Thuringia, Cliotzen in Bohemia; in the gold sands of Brazil, tlie Ural and Olahpian ; in veins in Siberia, Soutli Afi'ica ; also at Lead- hills in Scotland, and in basalt in north of Ireland. Lately Family.'] ANTIMONY — AESENIC-ANTIMONY — AESENIC. 279 large masses, one of 44,000 lbs. found near Disco Bay in Greenland, it is said in basalt, but contain nickel. (6.) Meteoric Iron. — Steel-gray and silver-white ; always contains nickel, witlr cobalt, copper, and other substances. Polished and etched with nitric acid, the surface is marked bylines intersecting at 60° or 120°, named Widmanstadt's figures. Has fallen from the sky in very many countries, — Siberia, Brazil, North America, South Africa, Hungary, Britain, and Ireland. 396. Antimony. — Sb. Hexagonal-rhombohedral ; E 87° 35', but very rarely crystallised, generally massive or spherical, and botryoidal. Cleavage, basal highly perfect ; E perfect, and - 2R imper- fect ; rather brittle and sectile. H. = 3...3-5; G. =-6-6... 6*8. Tin-white, with a grayish or yellowish tarnish. B.B. easily fusible ; on charcoal burns with a weak flame ; vola- tilises and forms a white deposit. Chem. com. antimony, with a little silver, iron, or arsenic. Andreasberg, Przi- bram, Sala, Allemont, and southern Canada. 397. Arsenic- Antimony, Allemontite. — Sb Asl Hexagonal-rhombohedral ; spherical or reniform. H. = 3-5; G. = 6-1. ..6-2. Tin-white to lead-gray, and tar- nished with brownish-black. B.B. gives out a strong smell of arsenic. Chem. com. 38 antimony and 62 arsenic; but other isomorphous compounds. Allemont j also Przibram, Schladming, and Andreasberg. 398. Arsenic. — As. Hexagonal-rhombohedral; E 85° 36'; OE, E, — -JE (Fig. 246) ; usually fine granular, rarely columnar, botry- oidal, or reniform. Cleavage, basal perfect, - |E imperfect : brittle. H. = 3-5 ; G. = 57 . . .5'8. Whitish lead-gray, but in a few hours acquires a grayish-black tar- nish. When broken or heated gives out arsenical odours. B.B. easily fusible, but on charcoal gives off dense white vapours, and maybe wholly volatilised without fusing. Chem. com. arsenic, with some antimony, and traces of iron, silver, or gold. Andreasberg, Annaberg, Schneeberg, Marienberg, 280 TELLURIUM— BISMUTH. [Native Metals Freiberg, Joachimsthal, Kapnik, Orawitza, Allemont, St. Marie aux Mines in Alsace, and Kongsberg ; Tyndrum in Perthshire ; also the Altai, North America, and Chili. Arsenic-silver is a compound with silver; Kongsberg. Arsenic-glance, -with 3 bismuth; H. = 2 ; G. = 5'36...5.S9 ; dark lead-gray ; takes fire at the flame of a candle, and burns; Marienberg. Arsenic is used in various pharma- ceutical preparations and metallurgic processes. 399. Tellurium. — Te. Hexagonal-rhombohedral ; E 86' 50^; small prismatic crystals ; usually massive, and fine granular. Cleavage, ooE perfect, basal imperfect; slightly sectile. H. = 2...2'5; G-. = 6-1 . . .6-3. Tin-white. B.B. very easily fusible ; burns with a^ greenish flame and much smoke, which forms a white ring with a reddish margin on charcoal. In con. s. acid forms a bluish-red solution. Chem. com. tellurium, with a little gold or iron. Facebay in Siebenburg. *400. Bismuth.— Bi. Hexagonal-rhombohedral ; E 87° 40'. Crystals E . OE, but often misshapen, also arborescent or reticulated ; often massive and granular. Cleavage, - 2 E 69° 28^, and basal perfect. Not malleable ; very sectile. H. = 2' 5 ; Gr. = 9-6 ...9-8. Eeddish silver-white, often with a yellow, red, brown, or parti-colour tarnish. B.B. very easily fusible^ even in the flame of a candle. On charcoal volatilises' leaving a citron-yellow coating. Soluble in nitric acid. Chem. com. bismuth ; often with a little arsenic or tellurium. Schneeberg, Annaberg, Marienberg, Joachimsthal ; Bieber ; Wittichen ; also Modum and Fahlun ; Bolivia ; near Eed- ruth ; Carrick-Fell in Cumberland, and Alva in Stirlino'- shire. Only source of bismuth. Maldonite or Bismuth-gold. — Silver-white with black tar- nish ; H. = l-5...2; G. = 8-2. ..9-7, contains 64'5 gold and 35-5 bismuth, or Au' Bi. Granite veins Maldon, Victoria. Zinc, said to occur native near Melbourne in Australia, is also hexagonal or rhombohedral. Family.] PYRITES. 281 Order VI. SULPHURETTED METALS. Crystallisation often tesseral (fths), rhombic (Id), or hexagonal and rhombohedral (|th), rarely other forms. H. = 1...7; G. = 3-4...9. Soluble in acids, and mostly B.B. easily fusible, many yielding fumes characteristic of sulphur, arsenic, or antimony. All (except one or two blendes) are opaque, and show metallic lustre and colour. Are all compounds of metals with sulphur, arsenic, or anti- mony, rarely witli selenium or tellurium. Occur frequently in veins, more rarely disseminated in rocks ; and many very valuable ores. Family I. — Pyrites. Crystallisation tesseral, rhombic, or hexagonal (chalco- pyrite tetragonal). Brittle, except bornite. H. = 3...6'5, the iron pyrites being the harder, the copper ores the softer ; G. = 4*1...8-1, but sulphur compounds = 4-1 ...5*3, arsenic or antimony 6-6...8'l, sulphur with arsenic or antimony 6... 6 -5. Colour mostly yellow, becoming lighter or more gray in those with less sulphur. They are all soluble in nitric acid, and solutions generally coloured ; B.B. all fusible, and give out fumes. a. Iron Pyrites. Nos. 400 to 404. **40L Pyrite, Iron Pyrites.— Fe", or [Fe S']. Tesseral, and dodecahedral-semitesseral. The cube ooOoo , then 0,^^ (Figs. 247, 248), and others (54 forms and about 90 combinations known), and macles (Fig. 249). In druses or groups, spheroidal or reniform, and massive, often in pseudomorphs. Cleavage, hexahedral or octahe- dral very imperfect or scarcely perceptible ; brittle. H. = 6...6-5 ; G. = 4-9...5-2. Bronze-yellow, inclining to gold- 282 MARCASITE. [Pyrites yellow, often with a brown or rarely variegated tarnish ; streak brownish-black. AVhen broken emits a smell of sulphur. In the closed tube sulphur sublimes. B.B. on charcoal burns with a bluish flame, and a strong smell of sulphur. In the red. flame fuses to a black- ish magnetic bead. Soluble in nitric acid with deposition of sulphur; scarcely afl'ected by h. acid. Chem. com. 46-7 iron and 5 3 '3 sulphur. V ery often contains gold, silver, or silicium, the gold occa- sionally in visible grains. Common in rocks of all ages and classes, often causing them to decompose. Fine varie- Fig. 248. Fig. 249. ties, Elba, Cornwall, Persberg, Traversella; also Alston Moor and Derbyshire. Auriferous pyrites, Beresof, Mar- mato, Mexico, Aedelfors in Sweden, and many parts of England and Scotland. Used for the manufacture of sul- phur, sulphuric acid, and alum. **402. Marcasite, White Iron Pyrites.— Fe'' = [Fe S']. Rhombic; ooP(7I/) 106° 5', J- foo 136° 54', Poo (/) 80° 20', P^ (r/) 64° 52', also P and OP (P) (Fig. 250). Crystals tabular or thin prismatic, or pyramidal. Macles frequent (Fig. 251) ; also cockscomb-like groups, or spherical, reniform, and stalactitic. Cleavage, ooP indistinct. Poo traces ; fracture uneven ; brittle. H. = 6 ... 6-5 ; G. = 4-65 ... 4*9. Pale, or grayish bronze- yellow, sometimes almost greenisli-gray ; streak dark Family.] PYRRHOTINE — LEUCOPYRITE. 283 Fig. 250. greenish-gray or brownish-black. B.B. and with acids acts like pyrite. It is more easily decomposed by the atm.osphere and changed into vitriols. Varieties are : — Radiated pijrites, radiated fibrous masses. Spear j^yrites, macles (Fig. 251) very fine at Littmitz, Przibram, Schemnitz, and Freiberg. Hepa- tic pyrites, or Leberkies, liver- brown, generally decomposing ; Harz, Saxony, Sweden, Derbyshire, and Cornwall. Cocks- comb pyrites, compound comb-like crystals, often greenish, or with a brown tarnish ; Derbyshire and the Harz. TFas- serkies or Hydrous pyrites contains water ; the Kyrosite copper and arsenic ; Lonchidite also arsenic. *403. Pyrrhotine, f Fe' = [Fe S], or Magnetic Pyrites. ( Fe^' Fe^"= [5 Fe S . Fe' S^. Hexagonal ; P 126" 38' to 50^ Crystals OP. ooP, or with P (P, M, r, Fig. 252) tabular or short prismatic, but rare. Commonly massive, granular, or compact. Cleavage, 00 P imperfect, laminar structure along OP ; brittle. H. = 3-5. ..4-5; G. = 4-5...4-6. Colour between bronze-yellow and copper-red, with a pinch- beck-brown tarnish ; streak grayish-black, more or less magnetic. Unaltered in the ^.^ closed tube ; in the open tube yields sulphu- rous fumes, but no sublimation. B.B. on charcoal in the red. flame fuses to a black strongly magnetic globule j soluble in h. acid. Chem. com. 63*65 iron and 36*35 sulphur, or 60-44 iron and 39*56 sulphur, in some with 2 to 6 nickel. Bodenmais, Fahlun, Kongsberg, Andreasberg, Moel Elion and Llanrwst in Caernarvonshire, Cornwall, Balahulish in Argyleshire, and Vesuvius ; also in some meteoric stones. Best distinguished by red colour, and solubility in h. acid. *404. Leucopyrite, Arsenical \a. Fe As==[Fe As^]. Pyrites, Lollingite. _ ] b. Fe' As^ - [Fe' As']. Ehombic; (xP 122° 26', Poo 51° 20', Po) 82° 21^ Crystals ooP . Poo (d^, a, Fig. 253). Generally massive, 284 MISPICKEL — COBALTINE. [Pyrites granular, or columnar. Cleavage, basal rather perfect, Pco imperfect; fracture uneven; brittle. H. = 5...5'5; G. = 7'0...7-4. Silver-white to steel-gray, with a darker tarnish ; streak grayish-black. B.B. on char- coal emits a strong smell of arsenic, and fuses to a black magnetic globule. Chem. com. a, 27-2 iron and 72-8 arsenic, with G. = 7-1... 8-7; or &, 32-2 iron and 66-8 arsenic, and G. = 6-3. ..7-0; but always 1-3 to 6 sulphur, and some 13-4 nickel, and 5 cobalt. Eeich- enstein in Silesia ; Schladming in Styria ; Lolling in Car- inthia; Andreasberg ; and Fossum in INorway. Used for the manufacture of arsenious acid. *405. MispiCKEL.— Fe S'+^Fe As, or [FeS'+Fe As^]. Ehombic; ooP 111° 12; ^ Foo 146° 28^ Poo 79° 22^ Poo 59°12; Crystals GoP. 1 Poo (ilf,>, Fig. 254) (the latter with horizontal striae) are short prismatic or tabular ; macles common, also massive, granular, or columnar. Cleavage, GoP rather distinct; fracture uneven; brittle. H. = 5-5 ..,6; G. = 6-0...6-2. Silver-white to steel- gray, with a grayish or yellowish tarnish; streak black. In the closed tube yields first a red, then a brown sublimate of sulphuret of arsenic, and then metallic arsenic. B.B. on charcoal fuses to a black magnetic globule. Soluble in n. acid, with separation of arsenious acid and sulphur. Chem. com. 19*6 sulphur, 46-1 arsenic, and 34*3 iron, but some contain silver or gold, others 5 to 9 cobalt. Freiberg, Altenberg, Joachims- thal, Zinnwald, Schlaggenwald, Andreasberg, Sweden, North America, and in many Cornish tin mines. Cohalt-mis- pickel, from Skutterud in Norway. Danaite and Plinian seem the same mineral. Used as an ore of arsenic or of silver. h. Cobalt-Pyrites, Nos. 405-409. *406. COBALTINE.— Co S' + Co As. Tcsseral and semitesseral, like pyiito ; also massive or granular, disseminated. Cleavage, hexahcdral perfect ; brittle. H. = 5*5 ; G. - G-0...G-3. Brilliant, reddish silver- Family.] SMALTINE — MODUMITE. 285 white or gray, with a grayish or yellowish tarnish ; streak grayish-black. B.B. on charcoal fuses with strong smell of arsenic to a gray, weak magnetic globule ; after roasting forms, with borax, a beautiful blue glass. Chem. com. 35*9 cobalt (with 3-6 iron), 44*9 arsenic, and 19-2 sulphur. Skutterud in Norway, Tunaberg, Querbach in Silesia, Sie- gen, and St. Just in Cornwall. Glaucodote. —Rhombic like mispickel. Dark tin- white ; streak-black; with 11-9 iron, 24*8 cobalt. Huasco and Valparaiso in Chili, Orawitza. *407. Smaltine. — Co As, or [Co As^]. Tesseral; chiefly the cube and octahedron (Fig. 255), the faces of the cube convex or cracked; also reticulated, reniform, or granular compact. Cleavage, traces along coOco and 0; fracture uneven ; brittle. H. = 5*5 ; G. = 6-4...7-3. Tin- white or steel-gray, with a dark-gray or iridescent tarnish ; streak grayish- black. Gives out an odour of arsenic when broken. In the closed tube gives no sublimate of arsenic. B.B. fuses easily, with a strong smell of arsenic, to a white or gray magnetic globule. Chem. com. 71*4 arsenic and 28-6 cobalt, but with 3 to 19 iron and 1 to 1 2 nickel ; others 1 to 3 bismuth. Schnee- berg, Annaberg, Eiechelsdorf, Allemont, Tunaberg ; Chat- ham in Connecticut ; Huel Sparnon, Doalcoath, and Eed- ruth in Cornwall. Gray Smaltine has 10 to 18 iron, and G. =^ 6'9 to 7 '3. Smaltine and cobaltine are used in pre- paring blue colours for painting porcelain and stoneware. 408. MoDUMiTE, Skutterudite. — Co' As', or [Co As']. Tesseral ; 0 and oo 0 oo , or granular. Cleavage, hexa- hedral distinct ; fracture conchoidal or uneven ; brittle. H. = 6; G.== 6-74. ..6-84. Tin-white to pale lead-gray, some with an iridescent tarnish. Lustre rather brilliant. In the closed tube gives a sublimate of metallic arsenic ; in other respects like smaltine. Chem. com. 79 arsenic, and 21 cobalt. Skutterud, near Modum in Norway. 286 LINNEITE — GERSDOEFFITE. [Pyrites 409. LiNNfiiTE.— (M; Co; FeO + (5?r, Pe'"), Tesseral ; in octahedrons and cubes, or macled ; also massive. Cleavage, hexahedral imperfect; brittle. H. = 5*5 j G-. = 4'9...5'0. Silver-white inclining to red, often with a yellowish tarnish; streak blackish^gray. B.B. on charcoal fuses in the red. flame to a gray magnetic globule, bronze-yellow when broken. Chem. com. 11 to 53 cobalt, 0 to 42-6 nickel, 2 to 5 iron, and 1 to 15 copper. Bastnses, Miisen near Siegen, also Maryland and Missouri. 410. Jyepoorite, Syepoorite.. — Co'. Massive. Steel-gray or yellowish. G. - 5*45. Chem. com. 65-2 cobalt, and 34 '8 sulphur. Jyepoor (misspelt Syepoor) near Eajpootanah in North-West India. The Indian jewellers use it to give a rose colour to gold. c. Nkhel-Pyrites. Nos. 410-418. 411. Grunauite, Saynite. Tesseral; 0 and coOgo ; also granular. Cleavage, octahedral ;' brittle. H. - 4-5 ; G. = 5*14. Light steel- gray inclining to silver-white, with a yellow or grayish tarnish. B.B. fuses to a gray, brittle, magnetic bead, yel- low on the fracture, and colours the support yellow. The solution in nitric acid is green. Chem.^ com. nickel, bis- muth, sulphur, iron, cobalt, copper, lead, in variable pro- portions. Griinau in Sayn-Altenkirchen. 412. Gersdorffite.— (Ni, Fe) As -f (Ni, Fe) S'. Tesseral; 0, ooOgc ; usually granular. Cleavage, hexahedral rather perfect; fracture uneven; brittle. H. ^5*5; G. = 6-0. ..6-7. Silver-white to steel-gray, with a grayish tarnish. In the closed tube decrepitates violently. B.B. fuses to a brittle, black, slag-like globule ; partially soluble in nitric acid. Chem. com. 35*2 nickel (with 2*4 to 6 iron, 0 to 3 cobalt), 45*4 arsenic, and 19*4 sulphur; but others give different formula, wiih 10 to 15 iron and 14 cobalt. The Harz, Schladming, Camsdorf, Sweden; also Spain and Brazil. Craigmuir, near Loch Fyne, with 23 nickel and 6 cobalt. Used as an ore of nickel. Korynite, in octahedrons, from Olsa, Carinthia ; and WolfacMte, from Wolfacli, but rhombic, give about 13 anti- mony, and 38 arsenic. Family.] ULLMANNITE — CHLOANTHITE. 287 413. Ullmannitk— M Sb+M or [Ni SF+NiS^. Tesseral j 0, ooOoo, ooO ; usually granular. Cleav- age, hexaliedral perfect; fracture uneven. H. = 5...5'5; G. = 6*2. ..6*5. Lead-gray to tin-white or steel-gray ; with a grayish-black or iridescent tarnish. B.B. fuses with dense fumes, and slight odour of arsenic ; soluble in con. nitric acid. Chem. com. 27*4 nickel, 57*5 antimony, and 15'1 sulphur, in some with 2 to 1 2 arsenic. Westerwald, Siegen, Harzgerode, Lolling, Lobenstein, and Bleiburg, Carinthia. 414. Breithauptite. — Ni^ Sb, or [Ni Sb]. Hexagonal; P 112° 10'. Crystals, thin striated hex- agonal tables of OP . ooP. B.. = 5; G. = 7'5...7'6, Bril- liant. Light copper-red, with violet-blue tarnish. B.B. fumes but fuses with great difficulty. Chem. com. 32*2 nickel, and 67*8 antimony, but mixed with 6 to 12 sul- phuret of lead. Andreasberg. 415. NiCKELiNE, Copper Nickel. — As or [Ni As]. Hexagonal; P 86° 50'. Crystals, ooP, OP, very rare and indistinct ; also arborescent, reniform, or generally massive. Fracture conchoidal and uneven ; brittle. H. ^ 5*5 ; G-. = 7*5...7'7. Light copper-red, with a tarnish first gray then blackish. It forms no sublimate in the closed tube. B.B. fuses with strong fumes to a white, brittle, metallic globule. Chem. com. 43*6 nickel and 56*4 arsenic, but with 0 to 2 cobalt, 0*2 to 9 iron, O'l to 4 sulphur, and 0 to 29 antimony. Freiberg, Schneeberg, Joachimsthal, Sangerhausen, Andreasberg, Chatham in Connecticut, Pen- gelly and Huel Chance in Cornwall, and Leadhills in Scot- land. Used as an ore of nickel. Plakodine is a furnace product, not a native mineral. 416. Chloanthite, White Nickel. — NiAs,M' [Ni As']. Tesseral ; 0, ooOoo , ooO ; also fine granular or com- pact. Fracture uneven ; brittle. H. = 5*5 ; G. = 6*4... 6*6. Tin-white, but first a gray, then a blackish tarnish, and loses its lustre. Yields an odour of arsenic when broken. In the closed tube forms a sublimate of metallic arsenic, and becomes copper-red. B.B. on charcoal fuses easily with much smoke, continues long ignited, becomes 288 RAMMELSBERGITE — CHALCOPYRITE. [Pyrites invested with crystals of arsenious acid, and leaves a brittle grain of metal. Chem. com. 28 nickel and 72 arsenic, but often with cobalt ; and many so-called smaltines belong to this species. Schneeberg, Eiechelsdorf, Allemont, Chat- ham in Connecticut. 417. Eammelsbergite. — M As. Ehombic; ooP 123°... 124°. G. = 7*099 ... 7*188. Colour tin-white, inclining to red on the fresh fracture. Otherwise like chloanthite, with which it occurs. The names are sometimes transposed. 418. Millerite. — Wi, or [Ni S]. Hexagonal-rhombohedral ; E 144° 8', in fine acicular prisms of ooP2 . E. Brittle. H. = 3'5 ; G. = 4*6 (or 5*26 ...5 '6 5). Brass or bronze yellow, with a gray or iridescent tarnish. B.B. fuses easily to a blackish metallic globule, which boils and sputters. In nitrochloric acid forms a green solution. Chem. com. 6 4 '4 nickel and 35 '6 sulphur. Johann-Georgenstadt, Joachimsthal, Przibram, Camsdorf, Eiechelsdorf, Pennsylvania ; near St. Austle in Cornwall, and at Merthyr-Tydvil. 419. Pentlandite, Inverarite. — 2 Fe' + W\. Tesseral j massive and granular. Fracture uneven ; brittle. H. = 3'5...4; G. = 4 6. Light pinchbeck-brown, with darker streak. Not magnetic. B.B. acts in general like pyrrhotine ; the roasted powder forms with borax in the red. flame a black opaque glass. Chem. com. 36 sul- phur, 42 iron, and 22 nickel j but mixed with pyrrhotine and chalcopyrite. Lillehammer in Southern Norway, near Inverary in Scotland, but only 1 1 nickel. d. Copper Pyrites. Nos. 419 to 421. 420. Chalcopyrite, \ Cu + Fe = [Cu S -f Fe S], or Yellow Copper Ore. j Gu' + Pe'^' = [Cu' S . Fe' S^]. Tetragonal and sphenoidal-hemihedric ; ^ P (P) with polar edges 71° 20'; Poo (h), 89° 10', 2Poo ((;) 126° 11', OP (tt), P and 00 Poo . Crystals generally small and de- formed (Fig. 256); macles very common, like Fig. 257. Most commonly compact and dissoiniiiated ; also botryoidal and rcniform. Cleavage, pyramidal 21* oo sometimes rather Family^ CHALCOPYRITE. 289 distinct; fracture conchoidal or uneven. H. = 3'5...4; Gr. = 4*1...4*3. Brass-yellow, often with a gold-yellow or iridescent {^peacock copper ore) tarnish ; streak greenish- black. B.B. on charcoal becomes darker or black, and on cooling red. Fuses easily to a steel-gray globule, which at length becomes magnetic, brittle, and grayish-red on the fractured surface. With borax and soda yields a grain of copper. Moistened with h. acid colours the flame blue. Chem. com. essentially 1 atom copper, 1 atom iron, and 2 atoms sulphur, with 34*5 copper, 30-5 iron, and 35 sulphur. The most abundant ore of copper. Anglesea (Parys Mine)? Derbyshire, Staffordshire, Cumberland ; Wicklow in Ire- land ; also in the Cornish mines (Gunnis Lake and St. Austle) ; in Scotland in Kirkcudbrightshire and Wigtown- shire, Tyndrum in Perthshire, Inverness-shire, Zetland, and other places. Of foreign European localities, Fahlun, Koraas, Freiberg, Mansfield, Goslar, Lauterberg, Musen, may be mentioned ; also in Siberia, California, Canada, the United States, and Australia. The ores raised in Cornwall and Devon give 8 per cent metal on the average ; and that picked for sale at Eedruth rarely yields 12, some- times only 3 or 4 per cent. The richness of the ore may in general be judged of by the colour ; if of a fine yellow hue, and yielding readily to the hammer, it may be con- sidered a good ore ; but if hard and pale yellow, it is assuredly a poor one, being mixed with iron pyrites. From Fig. 256. Fig. 257. U 290 BOENITE — DOMEYKITE. [Pyrites pyrite it is distinguished by yielding readily to the knife, by its tarnish, and by soon forming a green solution in nitric acid. The produce of the United Kingdom in 1871 was 97,129 tons ore, giving 6280 tons copper, worth £475,000. Cuban. — Cu S . Fe^ Tesseral ; or massive, with a hexahedral cleavage. G. = 4'02...4'18. B.B. very easily fusible, otherwise like chalcopyrite. Chem. com. 24 copper, 35 iron, and 41 sulphur. Bacaranao in Cuba, also Tuna- berg and Kafveltorp in Sweden. *421. BORNITE Variegated) ^ „, ^ ^3 c^^g.^e^S^ or Purple Copper. ) Tesseral. Crystals, goOoo , and ooOoo . 0, but rare, and generally rough or uneven ; also macles. Mostly massive. Cleavage, octahedral very imperfect ; fracture conch oidal or uneven ; slightly brittle, or almost sectile, H. = 3 j G. = 4*9. ..5*1. Colour between copper-red and pinchbeck- brown, with tarnish at first red or brown, then violet or sky-blue ; streak grayish-black. B.B. acts like chalcopyrite; soluble in con. h. acid, leaving sulphur. Chem. com. 3 atoms copper, 1 atom iron, and 3 atoms sulphur, with 55*6 copper, 16*4 iron, and 28 sulphur, but often, especially when compact, mixed, and then 56 to 71 copper, and 6 to 1 7 iron. Crystals near Eedruth and St. Day in Cornwall ; massive at Killarney in Ireland ; also Norway, Sweden, Mansfeld, Silesia, Tuscany, and Chili. An ore of copper. 422. DOMEYKITE.— Cu' As [Cu' As]. Botry oidal, reniform, or massive. Fracture uneven or conch oidal ; brittle. H. = 3 . . . 3 '5 ; G. = 7 '0 . . . 7 '5 . Tin or silver white, inclining to yellow, with an iridescent tarnish. B.B. fuses easily with strong odour of arsenic; not affected by h. acid. Chem. com. 71*63 copper and 2 8 '3 7 arsenic. Calabazo in Coquimbo and Copiapo in Chili. Also near Zwickau with H. = 5; G. = 6-8... 6*9. Condurrite. — Massive, soft, and soils the fingers. Frac- ture flat conchoidal. Colour brownish or bluish black. G. = 4-20...4'29. B.B. on charcoal fuses, with escape of arsenic va])ours, to a globule, which, on cooling, cracks, swells, and falls to pieces. With soda and borax leaves a Family] ARSENIURET OF MANGANESE — GALENA. 291 grain of copper. Seems an impure variety. Condurrow Mine and near Eedruth. Algodonite from Lake Superior ; Whitneyite from Mexico ; and Darwinite (88 copper) are also identical or similar. 423. Arseniuret of Manganese. — Mn^ As. Massive and botryoidal, granular or foliated. Fracture uneven ; brittle. G. = 5*55. Grayish-white, with a black tarnish. B.B. burns with a blue flame, and emits fumes of arsenic; soluble in nitrochloric acid. Chem. com. 42*75 manganese, 57*25 arsenic, with trace of iron. Saxony] 424. Laurite.— 12 Eu^' + Os'". Tesseral ; in very small grains or crystals of octahedrons and tetrakishexahedrons combined with cubes. Brittle. H. = 7*5; G. = 6*99. Dark iron-black, with brilliant lustre. Insoluble even in nitrochloric acid, Chem. com. 62*9 ruthenium, 5 osmium, and 32*1 sulphur. With gold, platina, and diamonds, in Borneo, and Oregon. FajViily II. — Lead Glance. Crystallisation, chiefly tesseral ; also rhombic and hexagonal-rhombohedral. H. = 1...2*5, rarely more ; G. = 4 '6... 8 '9, and mostly 5*5, or higher. Colours generally lead-gray, and more or less dark. All soluble in acids. B.B. all fusible, and mostly very easily, and easily reduced. They are compounds with sulphur, selenium, or tellurium, known by their fumes. Chiefly occur in veins and some valuable ores. '-^425. Galena, Sulphuret of Lead.— PV or [Pb S]. Tesseral ; crystals chiefly cube, octahedron, and rhombic dodecahedron ; seldomer 20 and 202. Also massive and granular, compact, or laminar j and in pseudomorphs of pyromorphite and other minerals. Cleavage, hexahedral very perfect ; fracture scarcely obser viable ; sectile. H. = 2*5; G. = 7'2...7*6. Lead-gray, with darker, or rarely iridescent, tarnish; streak grayish-black. B.B. decrepi- tates, fuses, and leaves a globule of lead ; soluble in nitric acid. Chem. com. 86*7 lead and 13*3 sulphur, but usually contains a little silver, — ranging from 1 to 3, or 5 parts in 10,000 j rarely 1 per cent or more. Some contain copper, 292 CUPEOPLT^rBITE — SELEXCOPPERLEAD. [LeoA Glo.nce zinc, or antimonv. others selenium, and others (the super- suJjjhurtf) probably free snlphiir (2 to 8 per cent). Most common ore of lead in many countries. Cornwall, Derby- shii^e (Castletovrn). AVales. Cumberland. Alston Moor. Durham ( Allenhead) : Isle of Man : Leadhills. Pentland Hills, LinhthgOTVj Inverkeithing. Monaltrie. Tyndrum, Strontian. Islay. and many other pkces in Scotland. In 1855 the produce was, — England. 59.592 tons : AVales, 34.373 : Isle of Man, 4645 : Ireland, 1105 : and Scotland, 3393 tons. The total produce was about 94.U00 tons ore, yielding 69.000 tons lead, worth £1,252.000 : and 761,490 ounces silver, worth £190,372. The price of lead was about £19 per ton, and each ton contained 11 ounces silver. 426. CUPROPLOIBITE. Tesseral ; massive, with distinct hexahedral cleavage. H. = 2'5: G. = 6'41...6'43. Blackish lead-gray: streak black. B.B. does not decrepitate. Chem. com. 65 lead. 19*9 copper, and 1 5 'I sulphur (^vith 0"5 sih^er). Chili. Probably a mixture. 427. Clausthalite. — Pb Se. Tesseral ; but massive and fine granular, with hexa- hedral cleavage. H . = 2 '5 . . . 3 : G. = 8 '2 . . . S '8. Lead-gray ; streak gray. B.B. on charcoal fumes, smells of selenium, colours the flarne blue, stains the support red, yellow, and white ; and volatilises, except a small remainder, without fusing. Chem. com. 7 2 "7 lead (with 11-6 silver), and 27*3 selenium. Lerbach, Zorge and Tilkerode in the Harz. T/Jkerodite, with 3 cobalt ; G. = 7*7 ; colours borax-glass smalt-blue. L^hrliochlfe ; Lehrbach and Tilkerode; with 17 to 45 mercury, seems a mixture. 428. Selencopperlead. — (6u, Pb) Se. Massive and fine granular. Sectile. H. = 2 5 ; G. = 5-6 ...7 "5. Light lead-gi'ay inclining to brass-yellow, or witli a bluish tarnish ; streak darker. B.B. like clausthalite, only some fuse slightly on the surfiice, others easily forming a gray metallic mass. Cliom. com. 30 to 35 selenium, 47 to 64 lead, and 4 to 16 copper (with 0 to 1'3 silver). Family^ ONOFRITE — AKGENTITE. 293 Tilkerode, Zorge, and near Gabel in Thuringia. Perhaps more than one species. 429. Onofrite. — Hg Se + 4 Hg S. Massive, and granular. H. = 2-5. Blackish lead-gray or steel-gray ; streak shining. In the closed tube wholly volatile with a black sublimate. With soda gives metallic mercury. Chem. com. 82*8 mercury, 6 '6 selenium, and 10 '6 sulphur. St. Onofre in Mexico, Zorge in the Harz. 430. TiEMANNiTE. — Hg Se, Of Hg' Se'. Fine granular ; brittle. H. = 2 '5 j G. = 7 • 1 . . . 7 -4. Bril- liant. Dark lead-gray. In the closed tube decrepitates, swells, fuses, and volatilises to a black and brown deposit. Only soluble in nitrochloric acid. Chem. com. 75 mercury, 25 selenium. Clausthal and Zorge. 431. Naumannite. — Ag Se = [Ag^ Se]. In thin plates and granular. Cleavage, hexahedral perfect. Malleable. H. = 2'5 ; G. = 8*0. Iron -black ; splendent. B.B. on charcoal fuses ; with soda a grain of silver ; easily soluble in con. nitric acid. Chem. com. 7 3 silver and 27 selenium, with 4*91 lead. Tilkerode. Silveiyhyllinglanz. — Massive, foliated ; perfect cleavage ; thin lamina flexible. H. = 1 . . . 2 ; G. = 5-8. . .5' 9. Dark gray. Chem. com. antimony, lead, tellurium, gold, and sulphur (Flattner). Deutsch-Pilsen in Hungary. *432. Argentite, Sulphuret of Silver. — Ag' = [Ag' S]. Tesseral; ooOcx) , 0, ooO, and 202 (Fig. 258). Crys- tals generally misshapen, with un- even or curved faces ; in druses, or linear groups ; also arborescent, ca- pillary, or in crusts. Cleavage, very indistinct traces along ooO and coOgo ; fracture uneven and hackly ; malleable and flexible. H. — 2 ... 2 '5 ; G. = 7 '0 ... 7 '4. Earely brilliant ; more so on the streak. Blackish lead- gray, often with a black, brown, or rarely iridescent tar- nish. B.B. on charcoal fuses, intumesces greatly, and leaves a grain of silver ; soluble in con. nitric acid. Chem. 294 ACANTHITE — STEOMEYERITE. [Lead Glance com. 87 silver and 13 sulphur. Freiberg, Marienl3erg, Annaberg, Sclineeberg, Joliann-Georgenstadt ; Joacliims- thal ; Schemnitz and Kremiiitz ; Kongsberg ; Huel Duchy, Dolcoath, Herland, and near Callington, in Cornwall ; Alva in Stirlingshire. Common ore at Guanaxuato and Zaca- tecas in Mexico, in Peru, and Blagodat in Siberia. Valuable ore of silver. Pohjargijrite, from AYolfach, gives 7 antimony. 433. ACANTHITE. — Ag. Ehombicj P middle edge 120° 36; ocP 110° 54'. Crystals, short pyramidal, often twisted. G. = 7"2...7"3. Splendent. Lead-gray, darker than argentite. Cheni. com. like argentite, thus dimorphous. Freiberg and Claus- thal on argentite, also at Copiapo. 434. AXTDIOXY-SlLVER,DlSCRASITE. — Ag' ^hAo Ag'Sb. Ehombic; P with polar edges 132° 42' and ' 92°, ocP 120° nearly. Crystals short prismatic or thick tabular, and vertically striated ; macles united by a face of ooP ; often in stellar groups (Fig. 259) ; also mas- sive or granular. Cleavage, basal and Px distinct ; ocP imperfect ; rather brittle, and slightly malleable. H. = 3 -5 ; G. = 9 '4 . . . 9*8. Silver- white to tin-white, with a yel- low or blackish tarnish. B.B. fuses easily ; fumes, staining the charcoal white, and leaves a grain of silver; soluble in nitric acid. Chem. com. 64 to 84 silver, and 36 to 16 antimony. Andreas- berg, AUemont in Dauphine, Spain, and Arqueras in Co- quimbo. A valuable ore of silver. 435. StromeyePvIte. — €u' -f Ag'. Ehombic ; isomorphous with redruthite. Crystals rare ; usually massive, or in plates ; fracture flat, con- choidal, or even; very sectile. H. = 2'5...3; G. = 6-2... 6-3. Bright. Blackish lead-gray. B.B. fuses easily to a gray metallic semimalleable globule. Chem. com. 534 silver, 31*2 copper, and 15*7 sulphur, but often indeter- minate proportions of silver 3 to 53, and copper 30 to 75. Schlangenberg in Siberia, Paidelstadt in Silesia, and Ca- temo in Chili. Ore of silver and copper. Family,] EEDRUTHITE — KUPFERINDIG. 295 **436. Eedruthite, Copper Glance. — G\jl = [C\i^ S]. Ehombic; ooP (o) 119" 35', P (P) middle-edge 125° 22', -|-P (a) middle-edge 65° 40', 2 Poo (d) middle-edge 125° 40; f Poo (e) middle-edge 65° 48'. Crystals OP , (5) ooP . (0) 00 Poo (p) (Figs. 260, 261), mostly thick tabular, with hexagonal aspect ; also macles ; and massive, in plates or lumps. Cleavage, ooP imperfect; fracture conchoidal or uneven ; very sectile. H. = 2-5...3 ; G. = 5-5...5-8. Eather dull ; brighter on the streak. Blackish lead-gray, with a blue or other tarnish. B.B. colours the flame blue; on charcoal in the ox. flame sputters and fuses easily ; in the red. flame becomes solid. With soda gives a grain of cop- per. Green solution in nitric acid leaving sulphur. Chem. com. 79-8 copper, and 20*2 sulphur. Saxony, Silesia, Norway, the Bannat, Siberia, and the United States ; near Eedruth and Land's End in Cornwall ; Fassnet Burn in Haddingtonshire, in Ayrshire, and in Fair Island, Orkney. Important copper ore. Digenite.—Msissive. G. = 4-568. ..4-680 ; in other re- spects like redruthite. Contains 70*20 copper, 29*56 sul- phur, and 0*24 silver. Sangerhausen, the Bannat, and Chili. 437. KuPFERiNDia, Covelline. — Cu. Hexagonal. Crystals ooP . OP rare ; usually reniform, and fine granular. Cleavage, basal often very perfect ; sectile, and thin laminae flexible. H. = 1*5...2; G. = 3*8 or 4-6. Dull resinous, inclining to metallic. Indigo-blue, inclining to black ; streak black. B.B. burns with a blue flame ; on charcoal like redruthite, but remains fluid in the inner flame; soluble in nitric acid. Chem. com. 66*7 cop- Fig. 260. Fig. 261. 296 EUKAIPJTE — SILVAXITE. [_Lead Glance per. and 33'3 sulphur. Vesumis. Sana-erhausen, Baden- weiler,^ Leogang. Chili, Angola in Africa, New Zealand, ^ ictoria. and Cairn Beg in Cornwall. -438. EuKAiRiTE. — Cu' Se -f Ag Se. Massive and fine gi^anular. Soft (cuts with the knife). Lead-gray: streak sliining. B.B. fuses to a brittle grav metallic grain. Chem. com. 43 silver. 25 '2 copper, "and 31-8 selenium. Skrikerum. Atacama. Chili. 439. Berzelixe. — Cir Se. ^ Crystalline, in thin dendritic crusts. Soft. Silver- white : streak shining. B.B. on charcoal fuses to a crrav. slightly malleable bead. With soda a grain of copper.' Chem. com. 61'5 cojDper and 3S'5 selenium. Skrikerum in Smoland, Lerbach in the Harz. CroohsUe. horn Ski^ikemm, contains 17 thalium. with copper, silver, and selenium. Is lead-gray, and B.B. colours the flame intense green. 440. Altaite. — Pb Te. Tesseral and granular : hexahedral cleava^^e. Fracture uneven: sectile. H. = 3...3-o: G. = Sd ...8-2. Tin-white mclming to yellow, with yellow tarnish. B.B. on charcoal colours the flame blue : m the red. flame fuses to a globule that almost wholly volatilises. Chem. com. 61 '9 lead, with 1*28 silver, and 38 "1 telluriimi. Sawodinski mine in the Altai : California. 441. XAGYACiiTE, Black or Foliated Tellurium. Tetragonal : P 137' 52', Fx 122' 50' and OP. Crvs- tals tabular, but rare : in general thin plates or foliated. Cleavage, basal very perfect ; very sectile : the thin lanmn-e flexible. H. = 1 ... Fo : G. = 6-85 ... 7-2. Splendent. Blackish lead-gray. B.B. fuses easily, with white fumes, and forms a yellow deposit on the charcoal ; with soda leaves a grain of gold ; soluble in nitric acid, with residue of gold. Chem. com. 51 to G 3 lead, 6 to 9 irold, 1 copper and silver, 13 to 32 tellurium, 3 to 12 sul])hur. and 0 to 4-5 antimony. Xagyag in Siebenburg, and Oflenbanya. 442. SiLVANiTE.— Ag Te^ + Au Tel Ehombic, Schrauff, (or Monoclimc ; C. = 55° 21^ ocP Family] HESSITE — MOLYBDENITE. 297 94° 26', -P^oo 19° 21', P^oo 62° 43'. Fwse and Von Kok- sharow.) Crystals very small, short acicular, and often grouped in rows like letters. Cleavage in two directions, one very perfect ; sectile, but friable. H. = 1*5...2 ; G. = 7 -9 9... 8 -3 3. Steel-gray to tin- white, silver- white, and pale bronze-yellow. B.B. on charcoal forms a white coating, and fuses to a dark-gray globule, with soda reduced to a malleable grain of argentiferous gold ; soluble in nitrochloric acid, depositing chloride of silver ; and in nitric acid leav- ing gold. Cliem. com. 59*6 tellurium, with 0*6 to 8*5 an- timony, 26-5 gold (in some 30), and 13-9 silver, with 0'2 to 15 lead. Offenbanya {Graphic Tellurium), Nagyag {Yel- low Tellurium), and California. 443. Hessite. — Ag Te. Ehombic or tesseral. Massive and granular ; slightly malleable. H. = 2'5...3 ; G. = 8-3...8'8. Blackish lead- gray to steel-gray. B.B. on charcoal fumes, fuses to a black grain with white spots, and leaves a brittle grain of silver. Chem. com. 62-8 silver, and 37*2 tellurium, but some {Fet- zite) 18 to 25 gold. Sawodinski mine in the Altai, Nagyag, and Eezbanya. 444. Tetrad YMiTE. — 2 Bi Te'-fBi S'. Hexagonal-rhombohedral ; 3K 68° 10'. Crystals 3E . OE ; almost always macles, with the faces of OE at 95° ; also granular foliated. Cleavage, basal very perfect ; sectile, and in thin laminae flexible. H. = 1...2 ; G. = 7*2 ...7 -5. Dull. Tin- white to steel-gray. B.B. on charcoal fases easily, occasionally with odour of selenium, staining the support yellow and white ; at length yields a white grain of metal, almost entirely volatile ; soluble in nitric acid. Chem. com. 59'6 bismuth, 35*9 tellurium, and 4*5 sulphur, with traces of selenium. Schubkau near Schem- nitz, Deutsch-Pilsen in Hungary, San Jose in Brazil, Vir- ginia and Carolina. *445. Molybdenite.— Mo" = [Mo S]. Hexagonal; but only tabular or short prismatic crystals of OP . odP or OP . P. Generally scaly or curved foliated. Cleavage, basal very perfect ; very sectile, and thin laminae 298 STIBINE. [Gray Antimony flexible. Feels greasy. H. = 1 . . . 1 -5 ; G. = 4*6 = 4-9. Eeddish lead-gray ; makes a gray mark on paper, a greenish mark on porcelain. B.B. in the forceps, colours the flame siskin-green, but is infusible. On charcoal yields sulphu- rous^ fumes, and forms a white coating, but burns slowly and imperfectly. In warm nitrochloric acid forms a greenish, in boiling sulphuric acid a blue solution. Chem. com. 59 molybdena and 41 sulphur. Arendal, Altenberg, Ehren- friedersdorf, Zinnwald, Schlaggenwald, Mont Blanc, Shutes- bury in Massachusetts, in Maine, Haddam in Connecticut ; Yea in Victoria; Caldbeckfell in Cumberland, Shap in Westmoreland, Huel Gorland, and many Cornish mines ; Peterhead, and near Inverurie in Aberdeenshire, Corybuy. on Loch Creran, and Glenelg. Eeadily distinguished from graphite by its streak, lustre, gravity, and action before the blowpipe. Used for preparing blue carmine for colouring porcelain. Family III.— Gray Antimony Ore. Crystallisation rhombic, rarely tesseral or hexagonal. H. = 3...3-5, or less; G. = 4...6-8. Colour steel or lead gray. All soluble in acids with precipitates; generally very easily fusible, even in the flame of a candle, and give out fumes. *446. Stibine, Antimonite.— SV'' = [SV S']. ~ Ehombic ; P polar edges 109° 26\ and 108° 2lVooP 90° 5i\ Crys- tals a)P (m) . cx)Poo (o) . P (P), or with iP^ (a), 2P2 (h), fP2 (e), iP (5), (Fig. 262). Mostly long prismatic or acicular, with strong vertical stria3, often in druses or stellar groups ; also radiating, fibrous, or fine granu- lar. Cleavage, bracliy diagonal (0) highly perfect, and often horizontally striated ; also basal, 00 P, and macro- diagonal imperfect ; sectile. H. = 2 ; G. = 4'6...4-7. Bril- liant. Lead-gray, with a blackish or iridescent tarnish. 2G2. Ore Family.'] JAMESONITE — PLAGIONITE. 299 B.B. fuses easily, colouring the flame green, and volatilises, leaving a white coating on the support ; soluble in warm h. acid. Chem. com. 71*8 antimony and 28*2 sulphur. Frei- berg, Wolfsberg in the Harz, Przibram, Felsobanya, Krem- nitz, Schemnitz, Auvergne, Spain, and North and South America; also near Melbourne, Victoria; St. Stephen's, Padstow, and Endellion in Cornwall; Glendinning in Dumfriesshire, New Cumnock in Ayrshire, and in Banff- shire. Chief ore of antimony. 447. Jamesonite.— PV' SV = [3 Pb S . 2 SF S^. Ehombic; ooP lOT 20'. Crystals ooP . ooPoo , long prismatic, parallel, or radiating. Cleavage, basal very per- fect, ooP and brachydiagonal imperfect ; sectile. H. = 2... 2*5; G. =^ 5*5...5*7. Steel-gray to dark lead-gray. B.B. decrepitates, fuses easily, and wholly volatilises, except a small slag; soluble in warm h. acid. Chem. com. 44*5 lead, with 2 to 4 iron, 34*9 antimony, and 20*6 sulphur, Cornwall, Estremadura, Hungary, Siberia, and Brazil. 448. ZiNCKENITE.— PV Sb'^'. Ehombic; {d) 120' 39', Poo {o) 150° 36' (Fig. 263), but doubtful. Crystals, prismatic or acicular, vertically striated, and macled in threes. Cleavage, prismatic very imperfect ; fracture uneven; rather sectile. H. = 3...3*5; G. = 5*3...5*35. Dark steel-gray to lead-gray, with a steel-blue or iridescent tarnish. B.B. like jamesonite. Chem. com. 35*9 lead, 42 antimony, 22'1 sulphur, with 0*42 copper. Wolfsberg in the Harz. 449. PLAGIONITE.— Pb'' Sb"". Monoclinic; C. = 72° 28', P 134° 30' and 142° 3', -2P 120° 49'. Crystals thick tabular, minute, and in druses. Cleavage, — 2P rather perfect; brittle. H. = 2*5; G. = 5*4. Blackish lead-gray. B.B. decrepitates violently, fuses easily, sinking into the charcoal, and leaves metallic lead. Chem. com. 41 lead, 38 antimony, and 21 sulphur. Wolfsberg in the Harz. 300 BOULANGERITE— PLUMOSITE. [Gray Antimony 450. BOULANGERITE.— PV SV. Fine granular, columnar, radiating, or fibrous. Slightly sectile. H. = 3; G. = 5-8...6. Silky, metallic. Blackish lead-gray, with darker streak. B.B. like jamesonite. Chem. com. 60 lead, 22-8 antimony, and 18-2 sulphur. Molieres in France, Ober-Lahr, Lapland, and Siberia. Flumbostib or EmbritUte, Nertschinsk, only a variety. 451. Meneghinite.— Sb'''. Monoclinic. C. = 72° 8', ooP 140° 24^ Foo 70° Crys- tals, very small, acicular, chiefly of ooP^oo . ooP^'oo . ooP, but rare ; mostly fibrous. Cleavage, orthodiagonal distinct.' Splendent; lead-gray. H. = 3 ; G. = 6-34. ..6-37. Chem. com. 64 lead, 19 antimony, and 17 sulphur. Bottino in Tuscany, and near Schwarzenberg in Saxony. 452. Geokronite.— PV' (Sb^^; As"'). Ehombic; P polar edges 153° and 64° 45', ooP2 = I19° 44', mostly massive, or lamellar. Cleavage, ooP2 ; fracture conchoidal or even ; sectile. H. = 2 . , . 3 ; G. = 6 '45 ... 6 "5 4. Pale lead-gray, with a slight tarnish. B.B. fuses easily and volatilises. Chem. com. 67 lead, with 1 to 2 copper and iron, 16 antimony, with 47 arsenic, and 17 sulphur. Sala in Sweden, Meredo in Spain, and near Pietrosanto in Tus- cany. Kilbrkkenite, massive, granular, or foliated ; County Clare in Ireland. 453. Steinmannite.— Pb', Sb'". Tesseral ; 0 ; also botryoidal and reniform. Cleavage, hexahedral rather imperfect ; sectile. H. = 2*5 ; G. = 6-833.' Lead-gray. B.B. decrepitates violently ; on charcoal fuses readily, leaving lead and silver. Przibram. 454. Plumosite, Feather Ore.— PV Sb'". Ehombic ; isomorphous with stibine ; but acicular or ca- pillary, in felt-like masses, tl. = 1 . . . 3 ; G. = 5 '7. Dull or glimmering.^ Dark lead or steel gray, sometimes iridescent. B.B. and with acids acts like jamesonite, of which Eam- melsberg makes it a variety ; fuses even in the flame of a candle. Chem. com. 51 lead, 29-5 antimony, and 19*5 sul- phur. Wolfsberg, Andreasbcrg, and Clausthal ; Neudorf in Anhalt, Freiberg, and Scliemnitz. Ore Family.'] ENAEGITE — BERTHIERITE. 301 455. Enargite.— Gu" As^'' = [3 Cu^ S . As' S^]. Ehombic; ooP 97° 53', PoolOO° 58', mostly massive and granular. Cleavage, ooP perfect, brachy- and macro- diagonal less so; brittle. H. = 3 ; G-. = 4*3...4*5. Iron- black. In the closed tube yields first sulphur, then fuses. B.B. with borax, a bead of copper. Chem. com. 48'3 copper, 19*1 arsenic, and 32*6 sulphur. Morocacha in Peru. 456. DuFRENOYSiTE, DamouT. — 6u ^ As'^'l Tesseral. Crystals ooO . 202. Fracture uneven ; brittle. H. = 2...3j G. = 4*4... 4*7. Steel-gray; streak reddish-brown. In the closed tube gives a reddish-brown sublimate. B.B. fuses easily, leaving a grain of copper. Eeadily soluble in warm acids. Chem. com. 39-3 copper (with 2-8 lead, 1'3 silver), 31 arsenic, and 29*7 sulphur, but some agree with enargite, which thus dimorphous. Binnenthal, St. Gotthardt. 457. Skleroclase, Binnite. — PV^ As'". Ehombic; P polar edges 96° 31' and 102° 41'; ooP 93° 39'; Poo 63°. Crystals, thick tables or broad prismatic, acicular or fibrous ; very brittle and friable. Cleavage, basal perfect. H. = 3 ; G. = 5-55. Bright metallic. Dark lead- gray; streak reddish-brown. Chem. com. 57*2 lead, 20*7 arsenic, 22*1 sulphur, with traces of silver, copper, and iron. St. Gotthardt, with dufrenoysite. Jordanite, rhombic, with a hexagonal aspect, is very similar; but distinguished by distinct brachy diagonal cleavage and black streak, occurs with skleroclase. 458. WoLESBERGiTE.— Gu'^Sb'", or [Cm' S . SV S^. Ehombic; ooP 135° 12', ooP2 111°. Crystals tabular; also fine granular. Cleavage, brachydiagonal very perfect, basal imperfect ; fracture conchoidal or uneven. H. = 3*5 ; G. = 4*748. Lead-gray to iron-black, sometimes iridescent; streak black, dull. B.B. decrepitates, fuses easily, and with soda gives a grain of copper. Chem. com. 25*4 copper, 49 antimony, and 25*6 sulphur. Wolfsberg in the Harz. 459. Berthierite. — Fe', SV". Massive ; columnar or fibrous, with indistinct cleavage. 302 BISMUTHINE— KOBELLITE. [Gray Antimony H -2...3; G. = 4-0...4'3. Dark steel-gray, yellowish or reddish; easily tarnished. B.B. on charcoal fuses easily, with fumes of antimony, to a black magnetic slag ; soluble m n. acid. Chem. com. sulphurets of iron and antimony in variable proportions, or 9-8 to 16 iron, 52 to 61*6 anti- mony, and 29-1 to 31 sulphur. Auvergne and Anglar in France, Braunsdorf in Saxony, Tintagel and Padstow in Cornwall. In France used as an ore of antimony. 460. BiSMUTHiNE. — Bi''' = [Bi' S']. ^ Ehombic; coP 91° 30^ Crystals long prismatic or acicular, with strong striae j also granular or columnar, foliated or radiated. Cleavage, brachydiagonal perfect' macrodiagonal less distinct; sectile. H. = 2...2-5; G. = 6-4. ..6-6. Light lead-gray to tin-white, with a yellowish or iridescent tarnish. B.B. on charcoal fuses easily in the inner flame, sputters, and yields a yellow coating with a grain of bismuth ; soluble in nitric acid. Chem, com. 81-2 bismuth and 18-8 sulphur. Eiddarhyttan, Bastnaes, Jo- hann-Georgenstadt, Altenberg, Joachimsthal ; Haddam in Connecticut ; Ballarat in Victoria ; near Eedruth, Botal- lack, Dolcoath, and Herland in Cornwall, and Caldbeckfell in Cumberland. 461. AcicuLiTE, Needle-ore.— Pb'' Bi'''-f Cu' Bi'''. Ehombic ; long thin crystals embedded in quartz, often bent or broken, with strong vertical strise. Cleavage im- perfect ; fracture conchoidal or uneven; rather brittle. H. = 2*5 ; G. = 6-7...6'8. Blackish lead-gray or steel-gray^ with a brownish tarnish. B.B. fuses very easily, smokes, stains the charcoal white and yellow, and leaves a metallic globule; soluble in nitric acid. Chem. com. 36 lead, 11 copper, 36 bismuth, and 17 sulphur. Beresof in Siberia, and in Georgia. ' 462. KoBELLiTE.— Pb'' Bi'''-f PV' Sb'^ Eadiated columnar; soft. G. = 6-2. ..6-3. Blackish lead-gray; streak black. B.B. fuses (at first boiling, then quietly), and stains the charcoal wliite and yellow, and leaves a white grain of metal; soluble in con. h. 'acid. Chem. com. 53 lead, 20 bismuth, 10 antimony, and 17 sul- phur, tlvena in Nerike, Sweden. Ore Family.'] TETEAHEDRITE, 303 Family IV.— Gray Copper Ore. Crystallisation rhombic and tesseral. H. = 1...4, the ores of copper being above 3, the ores of silver below 3 ; G. = 4*2. ..6*3. Colour steel or lead gray, in a few inclin- ing to black or brown. All soluble in nitric acid. B.B. fusible, often easily, with fumes of sulphur or arsenic. Mostly sulphurets of copper and silver, with sulphurets of arsenic or antimony. '^-463. Tetrahedrite, f (Cu, Ag', Fe',Zn , Hy )' (SV", Fahlore, Gray Copper. ( As'"), or [4 Cu' S . Sb' S^. 0 0 202 Tesseral and tetrahedral. In crystals - ooO, — ^ (Fig. 264, and Figs. 19, 20). Macles (Fig. 265), not un- common ; most abundant massive and disseminated. Cleavage, octahedral imperfect, with traces in other direc- tions ; fracture conchoidal, ♦ uneven, or fine granular ; brittle. H. = 3...4; G. = 4-5....5-2. Steel-gray to iron- black; streak black (dark- red when containing zinc), B.B. on charcoal boils slightly, and fuses to a steel-gray slag, usually magnetic, and with soda gives copper. In nitric acid the powder forms a brownish-green solution. Chem. com. essentially^ Cu^ S in combination with Sb^ S^ But part of the copper is replaced by silver, iron, zinc, or mercury ; part of the antimony by arsenic. The pure an- timony (25 to 28 per cent) fahlores are dark coloured, contain most silver, and fusedin closed tube give a dark-red sublimate. Fig. 264. Fig. 265. 304 TENNANTITE — BOCJRNOXITE. [Gray Copjjer The pure arsenic (14 to 19 per cent) fahlores are paler coloured, contain no silver, and give in closed tube a sub- limate of sulphuret of arsenic. Analyses give 30 to 40 copper, 0 to 10 silver, 1 to 6 iron, 1 to 7 zinc, 0 to 7*5 mercury, and 23 to 27 sulphur. Harz, Miisen, Freiberg, Camsdorf, Alsace, Kremnitz, Kapnik ; Crinnis and other Cornish mines near St. Austle ; Airthrie near Stirling, and Sandlodge in Zetland. Those with 17 to 31 silver are the Silver Fahlore (Freiberg). Ore of copper and silver. 464. Tennaxtite.— (€u, Fe^ As"^ Tesseral ; like fahlore, and scarcely distinct. Cleavage, ocO very imperfect; brittle. H. = 4 ; G. = 4*3. ..4*5. Blackish lead-gray to iron-black ; streak dark reddish-gray. B.B. decrepitates, burns with a bluish flame and odour of arsenic, and fuses to a magnetic slag. Chem. com. 49 cop- per, 4 iron, 19 arsenic, and 28 sulphur. Eedruth and St. Day, Cornwall, and Skutterud. CopiJerUende, with brown- ish-red streak ; Gr. ^4-3; contains 8*9 zinc; Freiberg. 465. BouPvNOXiTE.— PV* Sb"'-j-Cu' Sb'". Ehombic; ooP {d) 93° 40^ Poo {n) 96° 13', Poo {e) 92° 34; OP (r), (xPoo (s), ooPoo {k) (as in Fig. 266, but in other position). Crystals generally thick tabular, very often macled by a face of 00 P, and several times repeated; ^ also granular or disseminated. Cleav- age, brachydiagonal imperfect, traces in other directions ; fracture uneven to conchoidal ; rather brittle. H. = 2-5. ..3; G. = 5-7. ..5-9. Lustre bril- liant metallic. Steel-gray, inclining to lead-gray and iron-black. B.B. usually decrepitates and fuses easily to a black globule, staining the char- coal first white, then yellow, and with soda leaves a grain of copper. In nitric acid a bhie solution. Chem. €om. 42*4 lead, 13 copper, 25 antimon}^, and 19*6 sul- l)hur. Harz (Neudorf), Ih'iiunsdorf, Kapnik, Servoz, Alais and Pontgibaud, Eedruth and Beeralston. WblcMte from Wolch in Carinthia is only a variety. n i ^ TL S I Fig. 260. Ore Family.'] FEEIESLEBENITE — POLYBASITE. 305 466. Freieslebenitk— Ag' SV" + PV' Sb^^ Monoclinic; C. = 87° 46' ; ooP 119° 12^ P'^oo 31° 4r, in prisms with curved reed-like faces and strong vertical striae. Macles intersecting ; also massive. Cleavage, ooP perfect ; fracture conchoidal or uneven j rather brittle. H. = 2. ..2*5; G. = 6'2...6*4. Steel-gray to dark lead-gray; streak the same. B.B. on charcoal fuses to a grain of silver. Chem. com. 22 '5 silver, 32*4 lead (with copper), 2 6 '8 an- timony, and 18 '3 sulphur. Pare. Freiberg in Saxony; Hiendelaencina, Spain. Diaphorite with the same chem. com., but in rhombic crystals, with G. =5-90. At Przibram alone, also at Frei- berg. 467. Stephanitk— Ag' Sb"'- [5 Ag' S . SV S']. Ehombic; ooP {o) 115° 39', P (P) middle edge 104° 20', 2Poo {d) middle edge 107° 48', OP {s\ ooPoo {p\ (Figs. 267, 268), thick tabular or short prismatic. Macles frequent, repeated three or four times ; also massive. Cleav- age (d and j?), both imperfect ; fracture conchoidal or un- Fig. 268. even; sectile. H. = 2...2'5; G. = 6*2. ..6-3. Iron-black to blackish lead-gray, rarely iridescent. B.B. on charcoal (odour of arsenic) fuses to a dark-gray globule ; with soda, a grain of silver. Chem. com. 6 8 '5 silver, 15 '3 antimony, and 16-2 sulphur, but with under 5 iron, 4 copper, and 3*3 arsenic. Freiberg, Schneeberg, Johann-Georgenstadt, and Annaberg ; Joachimsthal and Przibram, Schemnitz, the Harz, Mexico, Peru, Siberia, and Cornwall. Valuable ore of silver. 468. Polybasite.— (Ag , Cu')^ (Sb'", As'"). Hexagonal; P 117°. Crystals OP . oo P and OP . P X Fig. 267. 306 STERNBERGITE — WITTICHENITE. [Gray Copper (Fig. 269), tabular, and often very thin ; also massive. Cleavage, basal imperfect ; sectile, and easily frangible. H. = 2...2'5; G. = 6"0...6*25. Iron-black; in very ^ thin lamellae, translucent red. B.B. decrepitates slierhtly, and fuses very easily. Chem. com. 64 Fiff 269 o J ? J J to 72 silver, 3 to 10 copper, 16 to 17 sulphur, 0*2 to 8 antimony, and 1 to 6 arsenic. Freiberg, Joachims- thal, Schemnitz, Guanaxuato, Nevada, and Idaho. Eich ore of silver. 469. STERNBERGITE.— (Ag + 2 Fe ) ¥q"\ Ehombic ; P middle edge 1 1 8°. Crystals usually thin tabular, in macles or in fan-like and spheroidal groups. Cleavage, basal very perfect ; sectile, and flexible in thin laminse. H. = 1...1*5; G. 4*2. ..4-25. Dark pinchbeck- brown, often a violet-blue tarnish ; streak black. B.B. on charcoal fuses to a magnetic globule covered with silver, with borax, a grain of silver ; decomposed by nitrochloric acid. Chem. com. 34*2 silver, 35*4 iron, and 30*4 sulphur. Joachimsthal, Schneeberg, and Johann-Georgenstadt. Flexible Sulj)huret of Silver is identical ; Hungary and Freiberg. 470. Stannine, Tin Pyrites.— Gu'^ Sn" + (FeVZu^ Sn". Tesseral ; in cubes very rare, generally massive and granular. Cleavage, hexahedral very imperfect ; fracture uneven or small conchoidal ; brittle. H. = 4 ; G. = 4*3... 4 '5. Steel-gray (yellowish from copper pyrites) ; streak black. B.B. on charcoal fuses, forming round the assay a white coating ; witli soda, a grain of copper ; easily decom- posed by nitric acid, leaving tin peroxide and sulphur ; the solution is blue. Chem. com. 26 to 32 tin, 24 to 30 cop- per, 5 to 12 iron, 2 to 10 zinc, and 30 sulphur. Huel Eock near St. Agnes, St. Michael's Mount, and Carn Brea, Cornwall ; and Zinnwald. Bell-metal ore. 471. Wittichenite, Cupreous Bismuth. — Ou'^ Bi''". Ehombic ; in tabular crystals like bournonite, but chiefly massive. Fracture uneven; sectile. H. =2*5; G. = 4*3... 5. Steel-gray, with lead-gray tarnish; streak black. B.B. fuses very readily, froths, and stains the charcoal yellow ; with soda, a grain of copper. Chem. Ore Family.'] EMPLECTITE — SPHALEEITE. 307 com. 38-5 copper, 42 bismuth, and 19*5 sulphur. Witti- chen in Schwarzwald. Klapvthite, long prismatic crystals ODP = 107°j with very distinct macrodiagonal cleavage, strongly striated and yellowish steel-gray, occurs with wittichenite, but gives Ou ' Br''', or 25-2 copper, 55*6 bismuth, and 19*2 sulphur. The Bismuthic silver of Klaproth is probably a mixture. 472. Emplectite. — Gu' Bi'''. Ehombic ; c»P, 102° 42', Poo 101° 38', in thin acicu- lar prisms, strongly striated. Cleavage, macrodiagonal per- fect, basal distinct ; sectile. Tin-white, with yellow tar- nish. H. = 2 ; G. = 5*14. ..5*26. In warm n. acid gives a dark greenish-blue solution. Chem. com. 19 copper, 62 bismuth, and 19 sulphur. Schwarzenberg in Saxony, Freu- denstadt in Wiirtemberg, and Copiapo, Chili. Family V. — Blendes. Crystallisation mostly tesseral ; cleavage distinct. H. = 3*5. ..4-5; G. = 3*5.. .4*9. Lustre adamantine or resin- ous ; more or less translucent. Colours and streak red, yellow, brown, or black. All soluble in acids. B.B. often decrepitate, but fuse with difficulty. "^*473. Sphalerite, Blende, Zinc-blende.— Zn' = [Zn S]. Tesseral and tetrahedral j 5, - - (sometimes as 0), ooO, 303 2 2' — ^-and ooOoo. Macles remarkably common, united by a face of 0 (Fig. 270) and several times repeated ; frequently massive and granular. Cleavage, ooO very per- fect; very brittle. H.=:3-5...4j G. = 3*9 ... 4*2. Semitransparent to opaque ; adamantine and resinous. Brown or black, also red, yellow, and green, rarely colourless or white. B.B. decrepitates often violently, but only fuses on very thin edges ; soluble in con. nitric acid, leav- ing sulphur. Chem. com. 67 zinc and 33 sulphur, but 308 WUEZITE— HAUERITE. [Blendes generally in the darker varieties with 1 to 15 iron, 0 to 3 cadmium. Very abundant, the Harz, Freiberg, Przibram, Schemnitz, Kapnik, North America, Peru, Cornwall, Derby- shire, Cumberland, Leadhills, Tyndrum, and Stotfield, near Elgin. Used for producing zinc vitriol, sulphur, and re- cently as an ore of zinc. 474. WuRZiTE.— Zn'. Hexagonal ; ooP . with strong horizontal strise. Cleavage, basal and prismatic. H. = 3'5...4j G. = 3.9 ...4*1. Brownish-black j streak light brown. Chem.com. like blende, which thus dimorphous. Oruro in Bolivia, and Przibram {Radiated blende). 475. VoLTZiNE. — 4 Zn + Zn. Hemispherical, curved lamellar incrustations. Fracture conchoidal. H. 4*5 ; G. = 3'5...3'8. Brick-red to yellow or brown. Opaque or translucent ; vitreo-resinous ; pearly. B.B. like zinc-blende; soluble in h. acid. Chem. com. 82'8 sulphuret and 17*2 oxide of zinc. Pontgibaud and Joa- chimsthal. 476. Alabandine. — Mn'. Tesseral ; 0 and ooOoo ; usually massive and granular. Cleavage, hexahedral perfect ; fracture uneven ; rather brittle. H. = 3 -5 . . . 4 ; G. = 3 '9 ... 4 '0. Opaque ; semi- metallic. Iron-black to dark steel-gray, brownish-black tarnish ; streak dark green. B.B. fuses on thin edges to a brown slag; soluble in h. acid. Chem. com. 63 man- ganese and 37 sulphur. Nagyag, Kapnik, Alabanda, Mexico, and Brazil. 477. Hauerite. — Mn'. Tesseral; 0, ooOoo , and ooO. Crystals single or in spherical groups. Cleavage, hexahedral perfect. H. 4 ; G. = 3*463. Semi -translucent on very thin edges; metal- lic-adamantine. Reddish-brown to brownish-black ; streak brownish-red. In the closed tube yields sulphur, and leaves a green mass, which B.B. becomes brown on the surface, and is soluble in h. acid. Chem. com. 46 man- ganese and 54 sulphur. Kalinka, near Neusohl in Hun- Family.] GREENOCKITE — PYRAKGYEITE. 309 478. Greenockite. — Cd'. Hexagonal and hemimorphic ; P 86° 21', 2P 123° 54'. Crystals 2P . OP . ocP . P, or P . 2P . ooP; attached singly. Cleavage, coP imperfect, basal perfect. H. = 3...3*5j G. = 4'8...4'9. Translucent; brilliant resinous, or adaman- tine. Honey or orange yellow, rarely brown ; streak yel- low. B.B. decrepitates and becomes carmine-red, but again yellow when cold ; fused with soda forms a reddish-brown coating on charcoal; soluble in h. acid. Chem. com. 77*6 cadmium, and 22*4 sulphur. Bishoptown in Eenfrewshire, Przibram, and Friedensville in Pennsylvania. Family VI. — Euby-Blendes. Crystallisation rhombohedral, monoclinic, or rhombic. Cleavage rarely distinct. H. = 1-5...2-5 ; G. = 3-5. ..8-2. Lustre adamantine. Colour yellow, red, or gray ; streak deep red, rarely brownish or yellow. Soluble in nitric acid. B.B. fusible and reduced, often with fumes, or sublime. Occur chiefly in veins in the igneous, the meta- morphic, and older stratified rocks. Those with silver are valuable ores of that metal. *479. Pyrargyrite, f A'g' SV" = [3 Ag' S . Sb' S^, or Bed Silver. { [Ag' Sb S']. Hexagonal-rhombohedral ; E (P) 108° 42', - ^-E 137° Fig. 271. Fig. 272. 5 8', OE, - 2E (r), E3, ooP2 (s), and ooE (I). Crystal. 310 PROUSTITE — MIAKGYRITE. [Ruhy-hUndes prismatic (Figs. 271, 272); macles common of various kinds ; also massive, dendritic, or investing. Cleavage, E rather perfect ; fracture conchoidal to uneven and splintery; slightly sectile, sometimes almost brittle. H. = 2...2-5; G. = 5*75. ..5-85. Translucent on the edges to opaque; crimson-red to blackish lead-gray ; streak cochineal to cherry-red. B.B. on charcoal fuses easily, gives out sul- phurous acid and antimony fumes, and leaves a grain of silver ; soluble in nitric acid, leaving sulphur and antimony protoxide ; solution of potash extracts sulphuret of anti- mony. Chem. com. 60 silver, 22*3 antimony, and 17*7 sulphur. Andreasberg, Freiberg, Johann-Georgenstadt, Annaberg, Schneeberg, and Marienberg; Przibram, Schem- nitz and Kremnitz, Kongsberg, Mexico, Nevado, etc. ; Huel Brothers and Huel Duchy in Cornwall. *480. Proustite.— Ag ' As'" = [3 Ag' S . As' S']. Ehombohedral, like pyrargyrite, except E, 107° 50'. Gr. Semitransparent to translucent on the edges. Cochineal to crimson red ; streak aurora-red to cochineal- red. B.B. arsenical odour, and leaves a brittle metallic grain difficultly reduced to pure silver; soluble in nitric acid, with remainder of sulphur and arsenious acid ; solu- tion of potash extracts sulphuret of arsenic. Chem. com. 6 5 '5 silver, 15*1 arsenic, and 19*4 sulphur. In the same localities with pyrargyrite, and both valuable ores of silver. (Eed orpiment has a lower specific gravity and yellow streak ; cinnabar volatilises before the blowpipe.) 481. MlARGYRITE. Ag' Sb'''. Monoclinic; C. - 81° 36', P 90° 53', - P 95° 59'. Crystals pyramidal, short prismatic, or tabular (Fig. ^ \ 273); also massive. Cleavage, indistinct IK — ----'^ traces ; fracture imperfect conchoidal or YIIZS:\^ uneven; sectile. H. = 2...2-5 ; G. = 5'2 Fig. 273. ...5-3. Opaque; thin splinters dark blood- red, translucent ; metallic adamantine. Blackish lead-gray to iron-black and steel-gray; streak cherry-red. B.B. with soda, a grain of silver ; with acids, like pyrargyrite. Chem. com. 37 silver, 41 antimony, and 2 2 sulphur. Briiunsdorf near Freiberg, Przibram, and Potosi. Family. ] XANTHOKON — KEKMES — CINNABAR. 311 Rittingerite.—MonodimG', C. = 88° 26', ooP 126° 18'. Crystals small tabular. Cleavage basal imperfect ; brittle. H. = 2-5...3. Translucent honey-yellow to red. Colour iron-black, on OP brown tarnished ; streak orange-yellow. B.B. melts easily, with arsenic fumes, leaving much silver. Joachimsthal. 482. XANTHOKON.— Ag' As'"-fAg' As'" Hexagonal-rhombohedral. Crystals very thin hexa- gonal tables, with R : OR 110° 30', -2R : OR 100° 35'. Cleavage, R and OR more or less perfect ; rather brittle, very easily frangible. H. = 2 . . . 2 '5 ; G. = 5 '0 ... 5 '2. Trans- lucent and transparent ; adamantine. Orange-yellow or brown ; streak slightly darker. In the closed tube fuses very easily, becomes lead-gray. Chem. com. 63*4 silver, 14*7 arsenic, and 21*9 sulphur. Himmelsfiirst Mine at Freiberg. Fireblende. — In thin tabular crystals (like heulandite), with one perfect cleavage ; sectile and slightly flexible. Gr. = 4*2 ... 4*3. Hyacinth-red. B.B. like pyrargyrite. Contains sulphur, antimony, and silver. Freiberg and Andreasberg. 483. Kermes, Antimony-blende.— Sb'"^ Sib. Monoclinic. Crystals acicular, capillary, and diverging ; also radiating fibrous. Cleavage, very perfect along the axis of the crystals, less perfect at right angles ; sectile. H. = 1...1-5 ; G-. = 4*5. ..4*6. Semitranslucent ; adaman- tine. Cherry-red ; streak similar. B.B. acts like stibine; soluble in h. acid ; in solution of potash the powder be- comes yellow and dissolves. Chem. com. 75*3 antimony, 19*8 sulphur, and 4*9 oxygen; or 70 sulphuret and 30 protoxide of antimony. Braunsdorf near Freiberg, Przi- bram, Allemont, and Southam, Canada. Zundererz, or Tinder ore, soft, flexible, tinder-like masses, cherry or blackish red, is a mixture. Andreasberg. 484. Cinnabar. — Hg'. Hexagonal-rhombohedral; R 71° 48', R. OR. ooR . fR (n, 0, m, i, Fig. 274). Crystals rhombohedral or thick tabular ; also disseminated and granular, compact, or earthy. 312 REALGAR— DIMOEPHINE. [Fiuhy -blendes Cleavage, ooE rather perfect ; fracture uneven and splin- tery ; sectile. H. = 2...2-5; a = 8-0...8'2. Semitranspa- rent, with circular polarisation like quartz, or opaque ; ada- mantine. Cochineal-red, with lead-gray and scarlet-red tarnish ; streak scarlet-red. In the open tube sublimes, partly as cinnabar, partly as metallic mercury ; perfectly soluble in nitrochloric acid, but not in hydro- chloric acid, nitric acid, or solution of potash. Chem. com. 8 6 "2 mercury and 1 3 "8 sulphur. Idria in Carniola, Almaden and Almadenejos in Spain, Wolfstein and Moschellandsberg in Ehenish Bavaria, Hartenstein in Saxony, Szlana and Eosenau in Hungary, Eipa in Tuscany ; New Almaden in California, Mexico, and Peru. Principal ore of mercury ; also used as a pigment. Fibrous and Hejoatic Cinnabar are mixtures. '^485. Eealgar, Eed Orpiment. — As'', or [As S]. Monoclinic ; C. - 66° 5^ ccP (Jf) 74° 26', Foo {n) 132° 2', ocF2 (/) 113° 16'. Crystals prismatic (Fig. 275); also massive and investing. Cleavage, basal and clinodiagonal rather perfect, prismatic im- perfect ; fracture small conchoidal to uneven or splintery ; sectile. H. = 1 'o . . . 2 ; G. = 3 '4 ... 3 "6. Semitransparent or opacjue ; resin- ous. Aurora-red; streak orange-yellow. In the closed tube sublimes as a dark-yellow or red mass ; B.B. on charcoal fuses and burns with a yel- lowish-white flame ; acids act on it with difficult}^ Chem. com. 70 arsenic and 30 sulphur. Kapnik, Xagyag, Felso- banya, and Tajowa, Andreasberg, St. Gotthardt, Vesuvius, and the Solfatara. 486. DiMORPHINE. — As'". Ehombic, in two types ; more common short prismatic, with GoP 96° 34' and Poo 103° 50'; the other more pyra- midal (but both derivable from form of orpiment — Kenngott). Very fragile. H. = 1*5; G. = 3*58. Splendent adaman- tine j translucent or transparent. Orange-yellow ; streak Fig. 275. Family.] ORPIMENT, 313 similar. Chem. com. 75-5 arsenic, and 24*5 sulphur. Sol- fatara, Naples. 487. Orpiment.— As''', or [As' S^]. Ehombic ; ooP (h) 117° 49', Po) (o) 83° 37', (xP2 {u), ooPoo (5). Crystals short prismatic (Fig. 276), disseminated, columnar or foliated. Cleavage, brachy diagonal very per- fect, striated vertically ; sectile, and in thin la- minae flexible. H. = 1-5. ..2; a -3-4. ..3-5. Semi- transparent or opaque ; resinous or pearly. Citron- yellow to orange-yellow. In the closed tube yields a dark-yellow or red sublimate ; fused with soda it yields metallic arsenic ; soluble in nitro- chloric acid, in potash, and in ammonia. Chem. com. 61 arsenic and 39 sulphur. Tajowa near Neusohl, Servia, Wallachia, Natolia, Felsobanya, Kapnik, and An- dreasberg ; the Solfatara, and Zimapan in Mexico. Fig. 276. 314 SULPHUR. [Sulphur Oeder VII. THE INFLAMMABLES. Named from the substances all burning before the blow- pipe, whereas the former minerals only fused or gave out fumes, and left a residue. Few of them are crystallised, and many are rather organic remains or rocks than simple minerals. In chemical composition a few are simple ele- ments, as sulphur and carbon, the others mostly formed on the plan not of the mineral kingdom, but of organic nature. Except the diamond, their hardness is low, or less than 2'5 ; and their specific gravity also 2'2, or under. Family I. — Sulphur. **488. Sulphur.— S. Ehombic ; P polar edges 106° 38^ 84° 58', middle edge 143° ir; (xP lOr 58; OP, iP, Poo. Crystals pyra- midal P. OP (F, C, Fig. 277), single or in druses; also reniform, spherical, stalactitic, disseminated, incrusting, or pulverulent. Cleavage, basal and ooP imperfect ; fracture conchoidal to uneven or splintery; rather brittle. H. = 1*5 c ...2'5; Gr. = 1'9...2-1. Transparent or trans- lucent on the edges ; resinous or adamantine. Sulphur-yellow, passing into brown and red, or into yellowish-gray and white. In the closed tube^it sublimes; at 227° Fahr. fuses, and at 518° takes fire and burns with a blue flame, forming sulphurous acid. Chem. com. sulphur, occasionally more or less mixed with other substances. Found chiefly in tertiary strata and near volcanoes. Sicily, at Girgenti, Cataldo, etc. ; tlie Lipari Islands, the Solfa- tara near Naples, Poland, Iceland, Java, Sandwich Islands, Family.] SELEN-SULPHUR — DIAMOND. 315 Peru, and Chili ; from springs at Aix-la-Chapelle, and in Scotland. Fused sulphur crystallises in transparent mono- clinic prisms, which soon become obscure and change their form when cold. Used for making gunpowder and sul- phuric acid ; in medicine, and for many other purposes. 489. Selen-Sulphur. Orange-yellow or yellowish-brown. Fuses readily in the closed tube, and volatilises. B.B. on charcoal burns, and gives out fumes of selenic and sulphurous acids. Con- sists of sulphur and selenium. Vulcano, Lipari, and Kilauea in Hawai. Native Selenium. — -Brownish-black or lead-gray. Thin splinters red translucent. H. = 2 ; G. = 4*3. Culebras in Mexico. Family II. — Diamond. *490. Diamond. — C. 0^0 Tesseral and tetrahedral - semitesseral ; ^ and - j mostly conjoined, ooO, ooOn, mO, mOn ; or the octahe- dron, rhombic dodecahedron, and hexakisoctahedron (Figs. 2, 3, 7, and 5). The crystals have often curved faces (Fig. 278), and occur loose and embedded singly. Macles common, united by a plane of 0, like Fig. 270. Cleavage, octahedral perfect ; fracture conchoidal ; brittle. H.-10; G., = 3-5. ..3-6. Trans- parent or translucent when dark-coloured. Eefracts light strongly; brilliant adaman- tine. Colourless, but often white, gray, or brown tints, also green, yellow, red, blue, ^ig. 278. and rarely black. Becomes positive electric by friction. Insoluble in acids, and B.B. infusible; but burns in oxygen gas, and forms carbonic acid. When air is excluded remains unchanged at the temperature of melting cast-iron, but at that of melting bar-iron changes into graphite. Chem. com. pure carbon. Hindostan on the east of the Deccan, between Pennar, Sonar, and the delta of the Ganges (lat. 14° to 25°) ; Borneo and Malacca ; Brazil in the district of Serro do Frio 316 GRAPHITE — ANTHRACITE. [Coals in Minas Geraes ; also in Borneo, Malacca, the Ural, Georgia, and North Carolina, California, Arizona, and the Sierra Madre, Mexico. Also recently, very many and of large size in South Africa, north of the Cape. Used as precious stones, also for cutting glass and polishing purposes. Eough diamonds till lately were worth 35s. to 45s. the carat (=3-7 grains). Cut as brilliants from £8 to £12 the carat, the value increasing as the square of the weight, and even more rapidly above 12 to 20 carats. In 1873 Cape diamonds were worth — yellows under 5 carats, 40s. to 50s. j above 5 carats, £3 to £4 per carat ; pure white stones under 5 carats, £3 to £4 ; and above 5 carats, £4 to £7 or more, according to form and lustre. ^Family III.— The Coals. **491. Graphite, Plumbago. — C. Hexagonal or monoclinic ; but only tliin tabular or short prismatic crystals of OP . ooP. Usually foliated, radiating, scaly, or compact. Cleavage, basal perfect; very sectile, flexible in thin laminae. Feels greasy. H. = 0-5... 1; G. = 1-9... 2-2. Opaque; metallic. Iron-black. Leaves a mark on paper. Is a perfect conductor of electricity. B.B. burns with much difficu%, the foliated more so even than the diamond ; and heated with nitre in a platina spoon only partially detonates. Chem. com. carbon, but mixed with iron, lime, alumina, or other matter. Pargas, Arendal, Passau, Spain, Ticonderoga in New York, Ceylon, Siberia, also Borrowdale in Cumberland, Glenstrathfarrer in Inverness-shire, Strathdon and other parts of Aberdeen- shire, Kirkcudbright, and Craigman in Ayrshire. At the latter it is evidently common coal altered by contact with trap. Is used for making pencils, and to form crucibles. *492. Anthracite. — Glance-Coal. Massive and disseminated ; rarely columnar, or fibrous and pulverulent. Fracture conchoidal ; brittle. H. = 2... 2-5; G. = 1-4... 1-7. Opaque; brilliant metallic. Iron- black or grayish-black; streak unaltered. Perfect con- ductor of electricity. Burns difficultly with a very weak Family.] COMMON COAL. 317 or no flame, and does not cake ; in the closed tube yields a little moisture, but no empyreumatic oil : detonates with nitre. Chem. com. carbon above 90 per cent, with 1 to 3 oxygen, 1 to 4 hydrogen, and 0 to 3 nitrogen ; and ashes chiefly of silica, alumina, lime, and peroxide of iron. Very common in some parts of the English, Scottish, and Irish coal-fields; in the Alps, as the Valais, Piedmont, Savoy, and Dauphine ; in the Pyrenees, and in various parts of France ; in Silesia, Bohemia, Saxony, and the Harz ; and in the United States, as in Ehode Island, Massachusetts, and above all in Pennsylvania. Used for manufacturing metals, and for economic and household purposes. *"'493. Common Coal, Black, Stone, Bituminous Coal. Compact, slaty, or confusedly fibrous ; often dividing into columnar, cubical, or rhomboidal fragments. Fracture conchoidal, uneven, or fibrous ; rather brittle or sectile. H. = 2...2-5; Gr. =^ 1-2...1-5. Vitreous, resinous, or silky in the fibrous variety. Blackish-brown, pitch-black, or velvet-black. Burns easily, emitting flame and smoke, with a bituminous odour ; heated in the closed tube yields much oil, and with powdered sulphur gives out sulphu- retted hydrogen. Chem. com. 74 to 90 carbon, with 0*6 to 8 or 15 oxygen, 3 to 6 hydrogen, 0*1 to 2 nitrogen, 0*1 to 3 sulphur, and 1 to 11 earthy matters or ash, in 100 parts. Slate-coal has a thick slaty structure, and an uneven fracture in the cross direction. Cannel-coal, a resinous, glimmering lustre, and a large or flat conchoidal fracture ; breaks into irregular cubical fragments, but more solid, and takes a higher polish than other varieties. It burns with a bright flame, and yields much gas. Torhanite, from Torbanehill near Bathgate, dull, brown, with yellowish streak, contains 9 hydrogen, and only 4 to 6 oxygen, with 20 to 25 ashes, chiefly alumina. Coarse or foliated coal, massive or lamellar, breaks into cubical or irregular angular masses, with a more splendent lustre and less com^pact texture than cannel-coal, and more easily frangible. Earthy coal, loose powdery masses, often brown or dirty in colour, and apparently semi-decomposed. Abundant in many lands, as 318 BROWN COAL — PEAT. [Mineral Besins in England, Scotland, and Ireland ; in Belgium and France, in Germany and Southern Eussia. British America and the United States possess immense fields, specially in the valley of the Mississippi. Also found in China, Japan, Hindostan, Aus- tralia, Borneo, and several of the Indian Islands. Its uses are too well known to need notice. In 1871 England pro- duced 90,128,087 tons; Wales, 11,620,000 ; Scotland, 15,438,291 ; and Ireland, 165,750; or in all 117,352,028 tons coal, worth £35,205,608. *494. Broato Coal. — Lignite, Jet. Distinctly vegetable in origin, the external form, and very often the internal woody structure, being preserved. The texture is compact, woody, or earthy. Fracture con- choidal, woody, or uneven ; soft and often friable. G-. = 0'5...1"5. Lustre sometimes resinous, mostly glimmering or dull. Brown, black, or rarely gray. Burns easily with an unpleasant odour ; colours solution of potash deep brown ; heated with sulphur evolves much sulphuretted hydrogen. Chem. com. 47 to 73 carbon, 2-5 to 7*5 hydro- gen, 8 to 33 oxygen (with nitrogen), and 1 to 15 ashes. Jet is pitch-black, with conchoidal fracture and resinous lustre. Brown coal occurs at Bovey Tracy in Devonshire ; also in Germany, Hungary, France, Italy, and Greece. The Siirturbrand of Iceland seems a variety. Used as fuel, but much inferior to common coal. The oolitic coals of York- shire, Antrim, Brora, Mull, and Skye, are intermediate varieties. *495. Peat. A mass of more or less decomposed vegetable matter of a brown or black colour, closely connected with coal, and, like it, rather a rock than a simple mineral. Contains 50 to 60 carbon, 5 to 6 hydrogen, 30 to 39 oxygen, 0 to 2 nitrogen, and 1 to 14 ashes in 100 parts. Common every- where in the colder parts of the earth. Family IV. — The Mineral Eesins. Named from their resemblance in aspect and composi- tion to vegetable resins, and many of them only such Family.] BITUMEN — ELATEKITE — ASPHALTUM. 319 slightly altered. Bitumen is fluid ; the others solid with H. = 1 to 2 or 2*5. Most are amorphous, a few crystalline and monoclinic. G. = 0-6... 1*6. Mostly resinous, colour- less or coloured, brown, yellow, or red, with paler streak. Soluble in acids, alcohol, ether, and oils. Melt readily, and burn with flame and smoke. Compounds of carbon and hydrogen, or also oxygen, and rarely nitrogen. But many very uncertain, and hardly true minerals. *496. Bitumen, Naphtha. — Off. Liquid. Colourless, yellow, or brown ; transparent or translucent. G. = 0-7... 0*9. Volatilises in the atmosphere with an aromatic bituminous odour. Chem. com. 84 to 88 carbon, and 12 to 16 hydrogen. Varieties are : — Naphtha. — Very fluid, transparent, and light yellow. Tegern Lake in Bavaria, Amiano near Parma, Salies in the Pyrenees, Eangun in Hindostan, Baku on the Caspian Sea, China, Persia, and North America. Used for burning and preparing varnishes. Petroleum. — Darker yellow or blackish-brown ; less fluid or volatile. Ormskirk in Lan- cashire, at Coalbrookdale, Pitchford, and Madeley in Shrop- shire ; St. Catherine's Well, south of Edinburgh ; Isle of Pomona ; and in many other parts of Europe. The oil- springs in the United States and Canada yield about £15,000,000 sterling worth in the year. 497. Elaterite, Elastic Bitumen,) ^^-2 Mineral Caoutchouc. ) Compact ; reniform or fungoid ; elastic and flexible like caoutchouc ; very soft. G. = 0-8... 1*23. Eesinous. Black- ish, reddish, or yellowish brown. Strong bituminous odour. Chem. com. 84 to 86 carbon, 12 to 14 hydrogen, and a little oxygen. Derbyshire, Montrelais near Nantes, and Woodbury in Connecticut. ^498. Asphaltum. Compact and disseminated. Fracture conchoidal, some- times vesicular ; sectile. H. = 2 ; G. = 1-1...1-2. Opaque, resinous, and pitch-black ; strong bituminous odour, espe- cially when rubbed. Takes fire easily, and burns with a bright flame and thick smoke ; soluble in ether, except a 320 PIAUZITE— IXOLYTE — AMBEE. [Mineral Beslns small remainder, ^vlncli is dissolved in oil of turpentine. Chem. com. 76 to 88 carbon, 2 to 10 oxygen, 6 to 10 hydrogen, and 1 to 3 nitrogen. Limmer near Hanover, Seyssel on the Ehone ; Yal Travers in Xeiifchatel, Lob- sann in Alsace, in the Harz ; Dead Sea, Persia, and Trini- dad j Cornwall, Hanghmond Hill, Shropshire ; East and AYest Lothian, Burntisland in Fifeshire, and near Strath- peffer in Eoss-shire. The last is similar to the Albertite from Hillsborough, in XeTv Brunswick. 499. Pliuzite. Massive; imperfect conchoidal : sectile. H. = 1"5; G. = 1'22. Dimly translucent on very thin edges; resinous. Blackish-brovrn ; streak yellowish-brown. Fuses at 600^ Fahr., and burns with an aromatic odour, lively flame, and dense smoke ; soluble in ether and caustic potash. Piauze in Carniola. 500. IXOLYTE. Massive; conchoidal fracture. H. = 1 ; G. = 1'008. Eesinous. Hyacinth-red ; streak ochre-yellow. Eubbed between the fingers it emits an aromatic odour, and be- comes soft at 119°, but is still viscid at 212^. Oberhart near Gloggnitz in Austria. *501. A3IBER, Succinite.— C'' 0. Eound irregular lumps, grains, or drops, often enclosing insects and fragments of plants. Fracture perfect con- choidal ; slightly brittle. H. -2...2-5; G. = 1-0...1T. Transparent to translucent or almost opaque : resinous. Honey-yellow, but from hyacinth-red or brown to yellowish- white ; also streaked or spotted. YTien rubbed emits an agreeable odour, and becomes negatively electric. It melts at 550^, emitting water, an empyreumatic oil, and succinic acid ; it burns with a bright flame and pleasant odour, leaving a carbonaceous remainder ; only a small part is soluble in alcohol. Chem. com. 79 carl)on, 10 '5 hydrogen, and 10*5 oxygen. Derived chiefly from an extinct coni- ferous tree {Pinites succinifer), and found in the tertiary and diluvial formations of many countries, especially North- ern Germany and shores of the I]aUic, Sicily, Spain, and Family. ] EETIN ITE — BERENGELITE. 321 Northern Italy; rarely in England, as on the shores of Norfolk, Suffolk, and Essex, and at Kensington, near Lon- don. Often contains fragments of extinct plants, of insects, spiders, and other arthropoda (above 1000 species). Used for ornamental purposes, and for preparing succinic acid and varnishes. 502. Reunite, Eetinasphalt. Roundish or irregular lumps. Fracture uneven or con- choidal ; very easily frangible. H. = r5...2 ; Gr, = 1*05... 1*15. Translucent or opaque; resinous or glistening. Yellow or brown. Melts at a low heat, and barns with an aromatic or bituminous odour. Chem. com. in general carbon, hydrogen, and oxygen, in very uncertain amount. Bovey, Halle, Cape Sable, and Osnabriick. 503. Walchowite.— C'' 0. Rounded pieces, Avith a conchoidal fracture. H. = 1 "5 ...2; G. — 1'035...1'069. Translucent, resinous. Yellow with brown stripes ; and a yellowish-white streak. It fuses at 482°, and burns readily ; soluble partially (7-5 per cent) in ether, and in sulphuric acid forms a dark-brown solu- tion. Chem. com. 80-4 carbon, 10'7 hydrogen, and 8*9 oxygen. "VYalchow in Moravia. 504. CoPALiNE, Fossil Copal, \^,o tt64 ^ Irregular fragments. H. = 1*5 ; G. = 1-046. Translu- cent, resinous, and light-yellow or yellowish-brown. Burns easily with a bright yellow flame and much smoke ; alco- hol dissolves very little of it, which is precipitated by water; becomes black in sulphuric acid. Chem. com. 85*54 car- bon, 11-63 hydrogen, 2*76 oxygen. Highgate near Lon- don. A similar resin from Settling Stones in Northumber- land, found in flat drops or crusts on calc-spar, is infusible at 500°Fahr.; G. = M6...1-54 ; and contains 85*13 car- bon, 10-85 hydrogen, and 3*26 ashes; or C H'.. 505. Berengelite. — C H'" 0'. Amorphous ; conchoidal fracture. Dark-brown, inclin- ing to green ; yellow streak. Resinous ; unpleasant odour, and bitter taste. Fuses below 212°, and then continues Highgate Resin. Y 322 GUYAQUILLITE — OZOKERITE. [Mineral Eesins soft at ordinary temperatures ; easily soluble in alcohol. Chem. com. 72-40 carbon, 9'28 hydrogen, 18-31 oxygen. St. Juan de Berengela in South America. 506. GUYAQUILLITE.— H^^ 0\ Amorphous; }delding easily to the knife, and very friable. = 1-092. Pale yellow. Slightly resinous. Fluid at 212°, viscid when cold ; slightly soluble in water and largely in alcohol, forming a yellow fluid with a bitter taste. Chem. com. 77-01 carbon, 8*18 hydrogen, and 14*80 oxygen. Guyaquil in South America. Bogbutter, from the Irish peat mosses, is similar ; melts at 124°, easily soluble in alcohol, and contains 73-70 car- bon, 12-50 hydrogen, and 13*72 oxygen. 507. Hartine.— 0^ Spermaceti-like masses. G. = 1-115. "White; without taste or smell. Becomes soft at 392°, and at 410° melts to a clear yellow fluid ; burns with a bright flame ; it is not soluble in water, very little in ether, and less in alcohol. Chem. com. 78-26 carbon, 10*92 hydrogen, 10-82 oxygen. Oberhart in Austria. 508. Middletonite.— C'° Br' + HO. Eound masses or thin layers. Brittle, but easily cut with a knife. G. = 1*6. Eesinous. Eeddisli-brown by reflected, deep-red by transmitted, light ; streak, light-brown. Becomes black on exposure. Chem. com. 86*43 carbon, 8-01 hydrogen, 5*56 oxygen. In the main coal seam at Middleton near Leeds, and at Newcastle. 509. Ozokerite, Native Parafine. — CH. Amorphous, sometimes fibrous. Very soft, pliable, and easily fashioned with the fingers. G. = 0-94. ..0-97. Glim- mering or glistening; semitranslucent. Yellowish-brown or hyacinth-red by transmitted, dark leek-green by reflected, light. Strongparafine or aromatic odour; fuses easily (at 1 44°, Schrutter; at 183°, Alalia rjiiffi) to a clear oily fluid, again becoming solid when cold, and at higher temperatures burns with a clear flame, seldom leaving any ashes ; readily sol- uble in oil of turpentine, with great difficulty in alcohol or ether. Chem. com. 85*7 carbon, and 14*3 hydrogen. Famihj.] HATCHETINE — SCHEERERITE. 323 Slanik and Zietriska in Moldavia, near Gaming in Austria, and Baku. Also Urpeth coal mine near Newcastle-on-Tyne. 510. Hatchetine, Mineral Tallow. Flaky, like spermaceti ; or sub-granular, like bees' wax ; soft and flexible. G. = 0*6. Translucent ; weak pearly. Yellowish- white, wax-yellow, or greenish-yellow. Greasy ; inodorous; readily soluble in ether. Chem. com. 85*91 carbon, and 14*62 hydrogen, or similar to ozokerite. Gla- morganshire (fusible at 115°); Loch Fyne near Inverary. Also Merthyr-Tydvil (melts at 170°), and Sooldorf in Schaumburg. 511. FiCHTELITE.— G* ff. Crystalline (mono clinic) lamellae, which swim in water, but sink in alcohol. White and pearly. Fuse at 115°, but again become crystalline on cooling ; very easily soluble in ether, and precipitated by alcohol. Chem. com. 88*9 carbon and 11*1 hydrogen. In pine-trees in a peat moss near Eedwitz in Bavaria. 512. Hartite.— C ff. Triclinic, but mostly like spermaceti or white wax, and lamellar. Sectile, but not flexible. H. =^ 1 ; G. = 1*046. Translucent ; dull resinous. White. Melts at 165°, and burns with much smoke ; very soluble in ether, much less so in alcohol. Chem. com. 87*8 carbon, and 12*2 hydro- gen. Oberhart in Austria. 513. KONLITK— C H. Crystalline folise and grains. Soft. G. = 0*88. Trans- lucent ; resinous. White, without smell. Fuses at 120° to 137° Fahr. ; soluble in nitric acid, and precipitated by water in a white crystaUine mass. Chem. com. 92*3 car- bon and 7*7 hydrogen. Uznach near St. Gallen, Eedwitz in Bavaria. 514. SCHEERERITE. Cff. Monoclinic ; tabular or acicular. Soft and rather brittle. G. = 1*0... 1*2. Translucent; resinous or ada- mantine. White, inclining to yellow or green. Feels greasy, has no taste, and when cold no smell, but when 324 IDRIALITE — OXALITE. [Infj:unmahle Salts heated a weak aromatic odour. InsoMDie in water : but readily in alcohol, ether, nitric, and sulphuric acid. Chem. com. 75 carbon, and 25 hydrogen. Uznach. Branchite, white, translucent, feels greasy, and fuses at 167°, is simi- lar. Monte Yaso in Tuscany. 515. Idrialite. — (Idrialine = C^H). Massive ; fracture uneven or slaty. Sectile. H. = I'O ...1-5; G. = l-4...1-6 (1-7. ..3-2). Opaque; resinous. Grayish or brownish black ; streak blackish-brown, inchn- ing to red. Feels greasy. Burns with a thick smoky flame, giving out sulphurous acid, and leaving some reddish- brown ashes. Chem. com. 77 idrialine (=947 carbon, and 5-3 hydrogen) and 18 cinnabar, with a little silica, alumina, pyrite,"and lime. The idrialine may be extracted by warm olive oil or oil of turpentine, as a pearly shining mass ; difficultly fusible. Idria. Fa^iily T. — Inflammable Salts. 516. Mellite, Honey Stone.— ^1 M' + 18 H. Tetragonal j P 93' o. Crystals, P alone, or with OP, Pod , and c^Px ; also massive and granular. Cleavage, P very imperfect ; fracture conchoidal ; rather brittle. H. = 2*0. . .2-5 ; Ct. = l-5...r7. Transparent to translucent; distinct double refraction ; resinous or vitreous. Honey- yellow to wax-yellow or reddish ; streak whitish. In the closed tube it yields water. B.B. carbonises without any sensible odour, at length burns white, and acts like pure alumina ; easily soluble in nitric acid or solution of potash. Chem. com. 40-3 melUc acid (M = C 0'), 14*4 alumina, and 45-3 water. In brown coal at Artern in Thuringia, and Lauscliitz in Bohemia ; Walchow in Moravia, creta- ceous ; in true coal at Malowka in Tula. 517. Oxalite, Humboldtine. — 2 Fe 6' -f 3 H. Capillary crystals ; also botryoidal or in plates, and fine irranular, fil^rous, or compact. Fracture uneven or earthy ; slightly sectile. H. = 2 ; G. = 2'15...2-25. Opaque; weak resinous or dull. Ochre or straw yellow. B.B. on char- coal becomes first black then red ; easily soluble in acids Family.^ WHEWELLITE — WATER — ICE. 325 with yellow colour. Chem. , com. 42*1 oxalic acid, 42*1 iron protoxide, and 15*8 water. In brown coal at Koloso- ruk near Bilin, Duisbiirg, and Gross Almerode in Hessia. 518. Whewellite. — Ca 0 + H. Monoclinic; 0. = 72° 41', ooP 100' 36'. Cleavage, basal perfect; very brittle. H. = 2-5...2-8 ; G. = 1-833. Transparent to opaque j vitreous. Colourless. Ctiem. com. 49'31 oxalic acid, 38*36 lime, 12*33 water. Locality unknown. Hungary 1 Though scarcely a simple mineral, the characters of water in its fluid and solid conditions may be noted here. ^-519. Water.— HO, or [ffO]. Fluid and amorphous. G. = 1*000 when pure, but sea- water 1*027 and 1*0285 at 62° Fahr. When pure it is w^ithout taste or smell, and colourless in small quantities, but in larger masses green or blue. Chem. com. hydrogen- oxide, with C^"9 oxygen and 11*1 hydrogen. Attains its greatest density at 39°*1, boils at 212°, and at 32° Fahr. freezes and changes to 520. Ice. Hexagonal-rhombohedral ; R 117° 23' (120°) ; usually six-sided tables of OE . ooR ; also acicular crystals, macled in delicate groups or stars with six rays. Cleavage, pro- bably basal. H. = 1*5 ; G:= 0*918 {Brunner at 32° Fahr., and quite pure). Dufaur, as mean of 22 observations, gives 0*9175. Hence 1000 water = 1089*5 ice; or water expands 1-1 1th in freezing. Transparent; vitreous. Col- ourless, but in large masses greenish or bluish. Refracts double. The water found on the earth is never pure, but con- tains more or less of various substances, — atmospheric air, carbonic acid, nitrogen gas ; silica, alumina, and salts (car- bonates, sulphates, nitrates, phosphates) of lime, magnesia, soda, potash, protoxides of iron and manganese ; or chlo- rides, and fluorides of the metallic bases ; and in the sea and some saline springs also iodine, bromine, and the rare metal thallium. 326 521. ADDITIONS AND COEEECTIONS. Page 104, line 7, for o, ]), 5, read r, p, s. Page 106, line 8 from below, for tourmeline, read tourmaline. Page 112, 3 from below, for ooPco, read ooPoo. Page 120, line 6 from foot, /or Melilite, read Mellilite. Page 124, No. 31. Leucite-— Yon Katb has recently shown that this mineral belongs not to the tesseral, but to the tetragonal system : the so-called icositetrahedron, like Fig. 6, being formed in the middle by 16 faces of a ditetragonal pyramid 4P2, and on the ends by 4 + 4 faces of the primary pyramid P, both very equally formed. 2Poo and ooP also occur as subordinate forms. Macles, marked by striae on the faces, and united by a face of 2Poo, are frequent. P has middle edge 73° 19|', polar edges 130° 3', and the middle edge of 4P2 is 133° 58'. Leucite thus, in its primitive form, comes close to idocrase, and adds another to the remarkable series of tetragonal minerals so characteristic of Vesuvius —idocrase, zircon, humboldtilite, sarkolite, meionite, and mizzonite. Page 152, after Augite msert Aegirine. Monoclinic ; striated or reed-like prisms of 86°*30' to 87° 45'. Cleavage, orthodiagonal perfect, less distinct clinodiagonal, and prismatic. H. =5-5...6; G. = 3*4. ..3-5 or 3'6. Yitreous, trans- lucent on edges, or opaque ; greenish-black. B.B. fuses easily, colour- ing the flame yellow ; scarcely afl*ected by acids. Chem. com. 3 (Na, Ca, Fe) Si + Fe Si^, with 50*5 silica, 217 iron peroxide, 10*1 iron (and manganese) jn'otoxide, 7*2 lime, and 10-5 soda, with a little magnesia and potash. Has the same relation to augite as arfvedson- ite to hornblende. Near Brevig and Barkevig in Norway. Page 175, line 16, for man tine, read Adamantine. Page 245, line 27, for 17, read 71. INDEX OF SIMPLE MINERALS. [The Numhers refer to the Paragraphs.] Abichite, 280. Abrazite, 58. Acanthite, 433. Achroite, 155. Aciculite, 461. Acinite, 98. Actinolite, 89. Actinote, 89. Adamantine-spar, 147. Adinole, 6. Adularia, 5. Aedelforsite, 42. Aegirine, 2^cig^ 326. Aeschynite, 343. Agalmatolite, 122. Agate, 1. Alabandine, 476. Alabaster, 202. Alalite, 90. Albertite, 498. Albite, 6. Algodonite, 422. Alizite, 127. AUagite, 96. Allanite, 166. Allemontite, 397. Allochroite, 129. Allogonite, 188. Allomorphite, 195. Allophane, 115. Alluaudite, 256. Almandine garnet, 129. ruby, 145. Alstonite, 198. Altaite, 440. Alum, 214. Aluminite, 207. Alumstone, 206. Alunite, 206. Alunogene, 216. Amalgam, 391. Amazon-stone, 5. Amber, 501. Amblygonite, 30. Amblystegite, 93. Amethyst, 1. Amianthus, 89, 90. Amphibole, 89. Amphodelite, 9. Analcime, 38. Anatase, 347. Anauxite, 78. Andalusite, 138. Andesine, 7. Anglarite, 253. Anglesite, 297. Anhydrite, 203. Ankerite, 245. Annabergite, 294. Anorthite, 9. Anthophyllite, 89. Anthosiderite, 160. Anthracite, 492. Anthraconite, 174. Antigorite, 82. Antimonite, 446. Antimony, 396. Blende, 483. , Ochre, 367. Silver, 434. White, 380. Antimony-Ores Gray fam., 446-462. White fam., 380-383. Antriniolite, 40. Apatelite, 220. Apatite, 187. Aphanese, 280. Aphrite, 174. Aphrodite, 126. Apophyllite, 46. Aquamarine, 152. Arseoxene, 312. Arcanite, 239. Arkansite, 345. Arfvedsonite, 89. Argentite, 432. Arquerite, 391. Arragonite, 179. Arsenic, 398. Arsenic -antimony, 397. Arsenic -glance, 398. Arsenic-silver, 398. Arsenical-pyrites, 404. Arseniosiderite, 267. Arsenite, 383. Asbestus, 89. Asparagus-stone, 187. Asphaltum, 498. Asteria, 147. Astrakanite, 244. Atacamite, 286. Augite, 90. Aurichalcite, 273. Autunite, 290. Automolite, 146. Avanturine, 1. Axinite, 134. Azorite, 340. Azurite, 271. Babingtonite, 99. Bagrationite, 166. Baikalite, 90. Balas Ruby, 145. Baltimorite, 81. Bamlite, 137. Barsowite, 16. Barystrontianite, 201. Baryta — Carbonate of, 197. Sulphate of, 195. Barytes, 195. 328 INDEX OF Baryto-calcite, 199. Baryto-celestiue, 200. Barytostrontiaiiite, 201. Bastite, 95. BatracMte, 156. Baiilite, 5. Beaiimoiitite, 43. Bell-metal ore, 470. Beraunite, 253. Bereugelite, 505. Bergmannite, 39. Bergseife, 107. Beiiinite, 27. Bertliierite, 459. Beryl, 152. Berzeline, 439. Berzeliite, 210. Berzelite, 304. Bendantite, 268. Bieberite, 225. Bimiite, 457. Biotite, 63. Bismuth, 400. Cupreons, 471. Gold, 400. Sulphiiret of, 460. Bismutliic silver, 471. Bismutliine, 460. Bismuthite, 318. Bismuth- ochre, 366. Bitter-spar, 175. Bitumen, 496. Elastic, 497. Bleiglas, 297. Bleinierite, 310. Blende, 473. Blende, radiated, 474. Blendes family, 473-478. Blendes, ruby, 479-487. Blodite, 244. Bloodstone, 1. Blue Iron, 253. Blue John, 180. Blue Spar, 25. Blumite, 336. Bodenite, 166. Bog-butter, 506. Bog-Iron ore, 332. Bole, 117. Bolognese-stone, 195. Boltonite, 156. Bousdorhte, 154. Boracite, 191. Borax, 231. , Bornite, 422. Botryogene, 219. Botryolite, 194. Boulangerite, 450. Bournonite, 465. Brandisite, 75. Braunite, 358. Breislackite, 90. Breithauptite, 414. Breunnerite, 176. Brevicite, 40. Brewsterite, 44. Brochantite, 288. Bromite, 323. Brongniartin, 205. Bronzite, 94. Vanadine, 92. Brookite, 345. Brown coal, 494. Brown-spar, 175. Brucite, 88, 157. Bucholzite, 137. Bucklandite, 133, 166. Buratite, 273. Bustamite, 96. Byssolite, 89. Bytownite, 9. Cacholong, 3. Cairngorum-stone, 1. Calaite, 26. Calamine, 250. Calamine, electric, 251. Calamite, 89. Calcareous-spar, 174. Calcedony, 1. Calcite, 174. Calc-spar family, 174-179. Calc-spar, 174. Caledonite, 301. Calomel, 320. Cancrinite, 19. (^andite, 145. ( ';i])(>i-c'iaiiite, 60. Cariiallilc, 213. (^aniat, 120. Cnriiclian, 1. Cass iter ite, 335. Cassiterotantalite, 339. Castor, 11. Cat's-eye, 1. Catlinite, 125. Caoutchouc, Mineral, 497. Cawk, 195. Celestine, 200. Cerasine, 303. Cerin, 166. Cerite, 168. Cerussite, 296. Cervantite, 382. Chabasite, 50. Chalcolite, 291. Chalcophyllite, 274. Chalcopyrite, 420. Chalcotrichite, 376. Chalilite, 4l. Chalk, 174. Black, 106. Chalybite, 245. Chanicrite, 70. Chert, 1. Chiastolite, 138. Childrenite, 189. Chiolite, 185. Chloanthite, 416. Chlorite, 67, 69. Chloritoid, 65. Chloromelan, 73. Chloropal, 161. Chloroph£eite, 162. Chlorophane, 180. Chlorophyllite, 154. Chlorospinel^ 145. Chondrodite, 157. Christianite, 9. Chromite, 328. Clirome-ochre, 373. Chrome, oxide of, 328. Chrysoberyl, 150. Cln-ysocolla, 270. Clirysolite, 156. Chrysopliane, 75. Clirysoprase, 1. Chrysotile, 81. Chusite, 156. Cimolitc, 122. Cinnabar, 484. Cinnamon-stone, 129. Cipollino, 174. J Citrin, 1. SIMPLE MINERALS. 329 ClansttLalite, 427. Clay family, 105-128. Clay, 106. ^ Clay stone, 5. Cleavelandite, 6. Clinoclilore, 69. Clintonite, 75. Cluthalite, 88. Coals family, 491-495. Coal, Anthracite, 492. Biwn, 494. Cannel, 493. Common, 493. Glance, 492. Colaalt, earthy, 362. encrusting, 293. Cobalt-hloom, 293. Cobaltine, 406. Coloalt-mispickel, 405. Cohalt-ochre, 364. Cobalt-pyrites, 406-410. Coccinite, 322. Coccolite, 90. Colophonite, 129. Colnmbite, 337. Comptonite, 41. Condnrrite, 422. Copaline, 504. Copiapite, 220. Copper, Native, 394. Black, 361. Blue, 271. Carbonate of, 271, 272. Emerald, 269. Glance, 436. Gray, 463. Purple, 421. Variegated, 421. Copperas, 218. Copperblende, 464. Copper-green, 270. Copper-mica, 274. Copper-nickel, 415. Copper- ore, Gray, fa- mily, 463-472. Red, 375. Eed,fam. of, 374-379. Yellow, 420. Copper-pyrites,420-422. Copper - salts family, 269-295. Coquimbite, 221. Coracite, 352. Cordierite, 154. Cormvallite, 276. Corundum, 147. Cotunnite, 306. Couzeranite, 16. Covelline, 437. Crednerite, 360. Crichtonite, 334. Crocoisite, 315. Cronstedtite, 73. Crookesite, 439. Crosstone, 54. Cryolite, 184. Cryptolite, 259. Cuban, 420. Cube-ore, 268. Cuboit, 38. Cuprite, 375. Cux)roplumbite, 426. Cyanite fam., 136-142. Cj^anite, 136. C a^pMse, 223. ' --■^ -^hane, 150. L)pix]ie, 132. Damouhite, 61. Danaite, 405. Danalite, 131. Darwinite, 422. Datholite, 194. Davidsonite, 152. Davine, 18. Dechenite, 312. Delessite, 69. Delvauxene, 262. Delvauxite, 262. Dermatin, 128. Descloizite, 312. Desmine, 42. Dewe^dite, 87. Diaclasite, 92. Diadochite, 261. Diallage, 92, 93. Diallogite, 246. Diamond, 490. Diaphorite, 466. Diaspore, 140. Copper, 281. Dichroite, 154. Didrimite, 61. Digenite, 436. Dihydrite, 281. Dimorphine, 486. Diopside, 90. Dioptase, 269. Diphanite, 76. Dipyr, 17. Discrasite, 434. Disterrite, 75. Disthene, 136. Dolomite, 175. Domeykite, 422. Dreelite, 196. Dufrenite, 254. Dufrenoysite, 456. Dysluite, 146, 329. Edi^^gtoxite, 53. Echvardsite, 258. Egeran, 132. Ehlite, 285. Eisenapatit, 256. ElcTolite, 18. Elaterite, 497. Electric Calamine, 251. Electrum, 388. Embolite, 324. Embrithite, 450. Emerald, 152. Emerald-nickel, 295. Emery, 147. Emerylite, 76. Emmonite, 201. Emplectite, 472. Enargite, 455. Enstatite, 94. Eosite, 312. Epichlorite, 69. Epidote, 133. Epistilbite, 45. Epsomite, 242. Epsom-salt, 242. Eremite, 258. Erinite, 276. Thomson, 108. Ersbyite, 16. Erythrine, 293. Esmarkite, 154. Euchroite, 279. Euclase, 151. Eudialite, 37. Eukairite, 438. 330 INDEX OF Eukolite, 173. Eulytine, 164. Euphyllite, 76. Eusynchite, 312. Euxenite, 341. Evansite, 27. Fahlore, 463. Fahlunite, 154. Faroelite, 40. Fassaite, 90. Faujasite, 52. Fayalite, 156. Featlier-alum, 214. Featlier-ore, 454. Feldstein, 5. Felsobanyite, 207. Felspar family, 5-15. Amorphous, 15. Compact, 5. Glassy, 5. Plagioclase, p. 109. Ferberite, 336. Fergusonite, 341. Fettbol, 117. Fibroferrite, 220. Fibrolite, 137. Fichtelite, 511. Figure-stone, 122. Fiorite, 3. Fireblende, 482. Fischerite, 27. Flint, 1. Flinty-slate, 1. Flos-ferri, 179. Fluellite, 185. Fluocerine, 183. Fluocerite, 182. Fluorite, 180. Fluor spar family, 180-194. Fluor-spar, 180. Foster] te, 156. Fowlerite, 96. Franklinite, 329. Freieslel)eiiite, 466. Frugardite, 132. Fuclisite, 61. Fuller's earth, 114. Gadolinite, 165. Gahnite, 132, 146. Galactite, 39. Galena, 425. Galmei, 251. Garnet family, 129-135. Garnet, 129. Gaylussite, 230. Gehlenite, 20. Gekros stein, 203. Gems family, 143-157. Geokronite, 452. Gersdorffite, 412. Gibbsite, 141. Gieseckite, 154. Gigantolite, 154. Giobertite, 176. Girasol, 3. Gismondine, 58. Glance-coal, 492. Glaserite, 239. Glauberite, 205. Glaubersalt, 217. Glaucodote, 406. Glaucolite, 16. Glauconite, 110. Glaucophane, 135. Glottalite, 50. Gmelinite, 51. Gokumite, 132. Gold, 388. Gold amalgam, 391. Goslarite, 224. Gotheite, 333. Grammatite, 89. Graphite, 491. Green earth, 109. Green Iron-earth, 164. Greenockite, 478. Greenovite, 344. Grengesite, 69. Groppite, 75. Groroilite, 363. Grossular, 129. Griinauite, 411. Guanite, 211. Gummierz, 351. Giirliofian, 175. Guyaquillite, 506. Gymnite, 87. Gypsum family, 202-211. Gypsum, 202. Gyrolite, 46. HAEMATITE, 330. Hafnefiordite, 10. Haidingerite, 209. Hair-salt, 216. Halloysite, 113. Haloid-stones family, 25-30. Halotrichite, 216. Harmotome, 54. Harringtonite, 40. Hartine, 507. Hartite, 512. Hatchetine, 510. Hauerite, 477. Hausmannite, 357. Hauyne, 33. Heavy-spar family, 195-201. Heavy spar, 195. Hedenbergite, 90. Hedyphane, 308. Heliotrope, 1. Helminth, 69. Helvine, 131. Hepatite, 195. Hercynite, 145. Herderite, 188. Herschelite, 56. Herrerite, 250. Hessite, 443. Hessonite, 129. Heterozite, 260. Heulandite, 43. Highgate resin, 504, Hisingerite, 159. Hjelmite, 340. Holmesite, 75. Honey-stone, 516. Hopeite, 186. Hornblende family, 89-104. Hornblende, 89. Horn-cobalt, 362. Horn-manganese, 96. Horn-silver, 319. Hornstone, 1. Humboldtilite, 21. Huniboldtine, 517. Humboldtite, 194. Humite, 157. Hureaulite, 260. Huron ite, 154. SIMPLE MINERALS. 331 Hversalt, 214. Hyacinth, 129, 143. Hyalite, 3. Hyalomelan, 104. Hyalosiderite, 156. Hydrargillite, 141. Hydroboracite, 193. Hydroborocalcite, 192. Hydromagnesite, 178. Hydromagnocalcite, 178. Hydrophane, 3. Hydrophite, 83. Hydropite, 96. Hypersthene, 93. Hypochlorite, 164. Hypostilbite, 42. Hystatit, 334. Ice, 520. Ice spar, 5. Iceland spar, 174. Ichthyopthalm, 46. Idocrase, 132. Idrialine, 515. Idrialite, 515. Ilmenite, 334. Ilvaite, 158. Indicolite, 155. Inflammable salts family, 516-518. Inverarite, 419. lodite, 321. lolite, 154. Iridium, 387. Iridosmium, 386. Irite, 331. Iron, Nat., 395. • Blue, 253. Carbonate, 245. Chromate of, 328. Phosphate of, 253. Pyrites, 401. Sparry, 245. Specular, 330. Sulphuret, 401. Titanitic, 334. Iron-clay, 106. Iron-flint, 1. Iron-froth, 350. Iron-mica, 330. Iron-ore, Bog, 332. Brown, 332. Green, 254. Magnetic, 327. Yellow, 220. Iron-ores, Oxidized, family, 327-334. Iron -salts family, 253-268. Iron-sand, 334. Iron-sinter, 264. Ironstone-clay, 245. Iserine, 334. Isopyre, 103. Ittnerite, 35. Ixolyte, 500. Jade, 91. Jamesonite, 447. Jarosite, 206. Jasper, 1. Jeffersonite, 90. Jet, 494. Johannite, 226. Jordanite, 457. Junkerite, 245. Jyepoorite, 410. Kainite, 244. Kakoxene, 253. Kammererite, 70. Kampylite, 308. Kaneelstein, 129. Kaolin, 105. Kapnite, 250. Karpholite, 23. Karphosiderite, 263. Karstenite, 203. Keilhauite, 172. Kerate, 319. Kermes, 483. ■ Kerolite, 121. Kibdelophan, 334. Kieserite, 243. Kilbrickenite, 452. Killinite, 12. Kirwanite, 24. Klaprothite, 471. Klinoclase, 280. Knebellite, 156, Kobaltbeschlag, 293. Kobellite, 462. Kollyrite, 119. Konlite, 513. Konigine, 289. Korynite, 412. Kottigite, 293. Koupholite, 22. Krablite, 5. Kraurite, 254. Kreittonite, 146. Krisuvigite, 288. Krokoit, 315. Krokydolite, 101. Kupferindig, 437. Kyrosite, 402. Labradoeite, 8. Lanarkite, 300. Lancasterite, 178 Langite, 289. Lanthanite, 248. Lapis-lazuli, 36. Lasionite, 28. Lasurstein, 36. Latrobite, 9. Laumonite, 59. Laurite, 424. Lavendulan, 293. Lazulite, 25. Lead, 392. Arseniate of, 308. Carbonate of, 296. Chromate, of, 315. Corneous, 303. Phosphate of, 307. Sulphate of, 297. Sulphuret, 425. Lead-glance family, 425-445. Leadhillite, 298. Lead-ochre, 372. Lead-salts family, 296-326. Lead-spar, 296. Leberkies, 402. Lederite, 51. Leelite, 5. Lehrbachite, 427. Lehuntite, 39. Lenzinite, 113. Leonhardite, 60. Lepidokrokite, 332. Lepidolite, 62. 332 INDEX OF Lepidomelane, 64. Lepolite, 9. Leuclitenbergite, 68. Leucite family, 31-37. Leucite, 31 ; page 326. Leiicophaue, 349. Leiicopyrite, 404. Levyne, 49. Llierzolite, 90. Libethenite, 283. Liebigite, 352. Lievrite, 158. Lignite, 494. Limbelite, 156. Lime, Borate of, 194. Lime, Carbonate of, 174. Fluate of, 180. Phosphate of, 187. Sulphate of, 202. Limonite, 332. Linarite, 302. Linneite, 409. Liroconite, 277. Lithia-mica, 62. Lithographic stone, 174. Lithomarge, 120. Lithoxylon, 3. Loam, 106. Loboite, 132. Loganite, 70. Lollingite, 404. Lonchidite, 402. Loweite, 241. Loxoclase, 5. Lnchssapphir, 154. Lncullite, 174. Lnmachello, 174. Lnnnite, 281. Lydianstone, 1. Maclurite, 157. Magnesia-apatite, 187. Magnesia, Borate of, 101 Carbonate of, 176, 177. Sulphate of, 242. Magnesite, 177. Magnetic iron, 327. Pyrites, 403. Magnetite, 327. Malachite, 272. Lime, 272. Siliceous, 270. Malacolite, 90. Malakon, 144. Maldonite, 400. Manganese, Arseniuret of, 423. Carbonate of, 246. Cupreous, 360. Earthy, 363. Red, 246. Manganese-ores family, 354-363. Spar, 96. Manganite, 356. Manganocalcite, 247. Marble, 174. Marcasite, 402. Marceline, 358. Margarite, 76. Margarodite, 61. Marl, 174. Marmolite, 81. Martinsite, 243. Martite, 330. Mascagnine, 238. Masonite, 65. Matlockite, 305. Maxite, 298. Meerschaum, 126. Megabasite, 336 Meionite, 16. Melaconite, 378. Melanochroite, 316. Melanite, 129. Melanterite, 217. Melinophane, 1 49. Mellilite, 21 . ' Mellite, 516. Melopsite, 120. Menacconite, 334. Mendipite, 304. Meneghinite, 451. Mengite, 350. Menilite, 3. Mercury, 390. Chloride of, 320. Sulpliurct, 484. Mesitine-spar, 176. Mesole, 40. Mesolite, 40. Mesoty])e, 39. Metachlorite, 69. Metallic stones family, 158-173. Metals, Nat., 384-400. Metaxite, 81. Miargyrite, 481. Mica family, 61-80. Lithia, 62. Magnesia, 63. Potash, 61. Microlite, 170. Middletonite, 508. Miemite, 175. Miesite, 307. Millerite, 418. Miloschin, 120. Mimetesite, 308. Mineral resins family, 496-515. Tallow, 510. Minium, Native, 371. Mirabillite, 217. Mispickel, 405. Misy, 220. Mizzonite, 16. Modumite, 408. Molybdena-ochre, 365. Molybdenite, 445. Monazite, 258. Monazitoid, 258. Monradite, 84. Monrolite, 137. Montebrasite, 30. Monticellite, 156. Moonstone, 5. Morenosite, 225. Morion, 1. Moroxite, 187. Morvenite, 54. INfountain Meal, 4. Muller's Glass, 3. Mullicite, 254. Murchisonite, 5. Muriacite, 203. Muscovite, 61. IMussite, 90. Myelin, 120. Mysorine, 272. Nacrtte, 79, 105. Nagyagite, 441. Naphtiia, 496. Natrolite, 39. SIMPLE MINERALS. 333 Natron, 227. Naumannite, 431. Needle-ore, 461. Needle-spar, 179. Needlestone, 40. Nenialite, 88. Neoctese, 266. Nepheline, 18. Nephrite, 91. Neurolite, 24. Newjanskite, 386. Newkirkite, 363. Nickel, Antimonial, 41 3. Arsenical, 415. Pyrites, 411- 419. „ White, 416. Nickeline, 415. Nickel-oclire, 294. Nigrine, 346. Niobite, 337. Nipholite, 185. Nitratine, 234. Nitre, 233. Nitrocalcite, 235. Nitromagnesite, 236. Nontronite, 161. Nosean, 34. Nussierite, 307. Nuttalite, 16. Obsidian, 15. Ochran, 117. Ochre, vellow, 332. Ochres,"363-373. Octaedrite, 347. Oerstedtite, 144, 171. Okenite, 47. Oligoclase, 10. Oligon-spar, 245. Olivenite, 278. Olivine, 156. Onkosin, 124. Onofrite, 429. Onyx, 1. Oolite, 174. Oosite, 154. Opal, 3. Orangite, 163. Orpiment, 487. ,, red, 485. Orthite, 166, Orthoclase, 5. ' Osmium-iridium, 386. '. Ottrelite, 66. Oxalite, 517. Oxidized Iron Ores : family, 327-334. Ozokerite, 509. Pachnolite, 184. Pagodite, 122. Paishergite, 96. Palagonite, 112. Palladinm, 385. Paratine, native, 509. Paragonite, 61. Pargasite, 89. Parisite, 249. Passauite, ]6. Paulite, 93. Pearl-mica, 76. Pearl-spar, 175. Pearlstone, 15. Peat, 495. Pechurane, 352. Pectolite, 48. Peganite, 27. Peliom, 154. Pennine, 68. Pentlandite, 419. Percylite, 286. Periclase, 142. Pericline, 6. Peridot, 156. Perowskine, 257. Perowskite, 350. Petalite, 11. Petroleum, 496. Petzite, 443. Phacolite, 50. Pharmacolite, 208. Pharmakosiderite, 268. Phenakite, 153. Phengite, 61. Phillipsite, 55. Phlogopite, 63. Phoenicochroite, 316. Pholerite, 79, 105. Phosgenite, 303. Phosphorite, 187. Phospliorochalcite, 281. Photicite, 96. Piauzite, 499. Pickeringite, 214. Picrolite, 81. Pier opharmacolite, '208. Picrophyll, 84. Picrosmine, 84. Piedmontite, 133. Pimelite, 127. Pinguite, 161. Pinite, 154. Piotine, 123. Pipe-clay, 106. Pipestone, 125. Pisolite, 174. Pissophane, 263. Pistazite, 133. Pistomasite, 176. Pitch-Blende, 352. Pitchstone, 15. Pitticite, 264. Pittinerz, 352. Plagionite, 449. Plakodine, 415. Plasma, 1. Plaster of Paris, 202. Platina, 384. Platiniridium, 384. Plattnerite, 353. Pleonaste, 146. Plinian, 405. Plinthite, 108. Plombgomme, 309. Plumbago, 491. Pliimbocalcite, 174. Plumbostib, 450. Plumosite, 454. Polianite, 355. Polishing slate, 4. Pollux, 13. Polyargite, 80. Polyargyrite, 432. Polybasite, 468. Poly erase, 349. Polyhalite, 204. Polyhydrite, 159. Polylite, 90. Polymignite, 348. Polysphserite, 307. Poonahlite, 40. Porcelain-earth, 105. . Porcelain-spar, 16. Porpezite, 388. Potstone, 71. 334 Potter's-clay, 105. Prase, 1. Praseolite, 154. Prasin, 285. Preclazzite, 175. Prelmite, 22. Preliiiitoid, 22. Prosopite, 185. Proustite, 480. Psilomelane, 359. Pucherite, 318. Pumice, 15. Pusclikinite, 133. Pycnite, 148. PjTaUolite, 102. Pja^argillite, 154. Pp-argyrite, 479. P}T:eneite, 129. P}Tite, 401. Pyrites family, 401-424. Ai\senical, 404. Col3alt, 406-410. Cocks-comb, 402. Hepatic, 402. Iron, 401-405. Magnetic, 403. Nickel, 411-419. Tin, 470. White Iron, 402. PjTochlore, 170. Pyrolusite, 354. Pyromorphite, 307. Pyrope, 130. Pyrophyllite, 77. Pyrophysalite, 148. Pyrorthite, 166. Pyrosclerite, 70. Pyrosnialite, 72. Pyroxene, 90. Pyrrliite, 170. Pyrrhosiderite, 333. Pyrrhotine, 403. Quartz family, 1-4. Quartz, 1. ,, spongiform, 4. Quicksilver, Nat., 390. Radioltte, 89. Rammelsbergite, 416. Realgar, 465. INDEX OF Red Copper Ore, family, 375-379. Reddle, 330. Redruthite, 436. Retinasphalt, 502. Retinite, 502. Reussin, 244. Rliaetizite, 136. Rhodium-gold, 388. Rhodizite, 191. Rhodochrome, 70. Rhodonite, 96. Rhomb-spar, 175. Rhyacolite, 5. Ripidolite, 67, 69. Rittingerite, 481. Rock-cork, 89. Rock-crystal, 1. Rock-leather, 89. Rock-salt family, 212- 244. Rock-salt, 212. Rock-soap, 107. Rock-wood, 89. Romanzowite, 129. Romeine, 325. Romeite, 325. Romerite, 219. Roselite, 208. Rosellan, 80. Rosite, 80. Rothoffite, 129. Rubellan, 63. Rubellite, 155. Rubicelle, 145. Ruby, Almandine, 145 Ruby, Elie, 130. Oriental, 147. Spinel, 145. Ruby- blende family, 479-487. Ruby-blende, 479. Ruby-silver, 479. Rutile, 346. Sacciiarite, 7. Salilite, 90. Sal-ammoniac, 237. Salamstein, 147. Salt, Common, 212. Epsom, 242. Glauber, 217. Saltpetre, 233. Samarskite, 338. Sanidine, 5. Saponite, 123. Sapphire, 147. D'Eau, 154. SajDphirine, 146. Sardonyx (Galcedony),l. Sai^kolite, 21. Sassoline, 232. Satin-spar, 179. Saynite, 416. Scapolite family, 16-24. Scapolite, 16. Scarbroite, 119. Scheeletine, 314. Scheelite, 326. Scheererite, 514. Schiller-spar, 95. Schorl, 155. Schorlamite, 343. Schorlite, 148. Schrotterite, 116. Scolezite, 40. Scorodite, 266. Scoulerite, 41. Seladonite, 109. Selbite, 319. Selencopperlead, 428. Selenite, 202. Selenium, Native, 489. S el en -sulphur, 489. Senarmontite, 381. Serbian, 120. Serpentine f am. , 81-88. Serpentine, 81. Sevbertite, 75. Shale, 106. Siderite, 245. Sideroplesite, 245. Sideroschisolite, 73. Silica, earthy, 4. Sillimanite, 137. Silvanite, 442. Silver, 389. Antimony, 434. Bismuthic, 471. Bromic, 323. Carbonate of, 319. Chloride of, 319. Horn, 319. I Iodic, 321. SIMPLE MINERALS. 335 Silver, Red, Ruby, 479. Sulpliuret, 432. . Silver Fahlore, 463. Silverphyllinglanz, 431. Sinopite, 117. Sinter, Iron, 264. Pearl, 3. Siliceous, 3. Sismondine, 65. Sisserkite, 386. Skleroklase, 457. Skolopsite, 126. Skutterudite, 408. Slate, Adhesive, 4. Polishing, 4. Slate-clay, 106. Slate-spar, 174. Smaltine, 407. Smithsonite, 250. Soapstone, 123. Soda, Carbonate, 227. Nitrate, 233. Sulphate, 217. Sodalite, 32. Sodium, Chlor. of, 212. Somervillite, 21. Sordawalite, 100. Spadaite, 86. Sparry iron -ores family, 245-252. Sparry iron, 245. Specular iron, 330. Sphserulite, 15. Sphaerosiderite, 245. Sphserostilbite, 42. Sphalerite, 473. Sphene, 344. Spinel, 145. Spodumene, 12. Stannine, 470. Stannite, 335. Stassfurtite, 191. Staurolite, 139. Staurotide, 139. Steatite, 71. Steinheilite, 154. Steinmannite, 453. Steinmark, 120. Stephanite, 467. Sternbergite, 469. Stibine, 446. Stiblite, 368. Stilbite, 42. Stilpnomelan, 74. Stilpnosiderite, 332. Stolpenite, 117. Stolzite, 314. Strahlstein, 89. Stroganowite, 16. Stromeyerite, 435. Stronmite, 201. Strontianite, 201. Struvite, 211. Succinite, 501. Sulphur, 488. Sunstone, 10. Surtur brand, 494. Susannite, 299. Syepoorite, 410. Sylvine, 212. Symplesite, 265 Tabergite, 70. Tabular-spar, 97. Tachyaphaltite, 144. Tachydrite, 213. Tachylite, 104. Tagilite, 284. Talc, 71. Tallow, Mineral, 510. Tantalite, 339. Tapiolite, 339. Tarnowitzite, 179. Tautolite, 156. Tectizite, 222. Tellurite, 374. Tellurium, 399. Black, 441. Foliated, 441. Graphic, 442. Tennantite, 464. Tenorite, 377. Tephroite, 156'. Teratolite, 118. Tetradymite, 444. Tetrahedrite, 463. Tetraphyline, 257. Thallite, 133. Tharandite, 175. Thenardite, 240. Therm onatrite, 221. Thomsonite, 41. Thorite, 163. Thraulite, 159. Thrombolite, 282. Thulite, 133a. Thummerstein, 134. Tiemannite, 430. Tile ore, 376. Tilkerodite, 427. Tin, Nat., 393. Oxide of, 335. Sulphuret of, 470. Tin-ore family, 335-352. Tin pyrites, 470. Tinder-ore, 483. Tinkal, 231. Tirolite, 275. Titanite, 844. Titanitic iron, 334. Topaz, 148. Gold, 1. Torbanite, 493. Tourmaline, 155. Travertino, 174. Tremolite, 89. Triclasite, 154. Tridymite, 2. Triphane, 12. Triphyline, 257. Triplite, 255. Tripoli, 4. Tritomite, 169. Trolleite, 27. Trona, 229. Troostite, 252. Tscheffkinite, 167. Tuesite, 113. Tufa, Calcareous, 174. Tungsten, 326. Tungsten -ochre, 369 . Turgite, 333. Turquoise, 26. Tyrite, 342. Ullmannite, 413. Uralite, 89. Ural-orthite, 166. Uran-mica, 290. Uranite, 290. Uranium-ochre, 370. Uranotantalite, 338. Urao, 229. Uwarowite, 129. Yalentinite, 380. 336 IXDEX OF SIMPLE MINERALS. Vanaclinite, 311. Yariscite, 26. Varvicite, 354. Yaiiquelinite, 317. Yerde antique, 174. Yermiciilite, 70. Yesiivian, 132. Yillarsite, So. Yiolan, 135. Yitriol, Bine, 223. Cobalt, 225. Green, 218. Iron, 218. Eed, 219. Uran, 226. White, 224. Yitriol- oclire, 220. Yivianite, 253. Yoglite, 352. Yolbortliite, 287. Yoltaite, 215. Yoltzine, 475. Yoranlite, 25. Yulpinite, 203. Wad, 363. Y'agnerite, 29. Walcliowite, 503. Y^alkerde, 114. Warringtonite, 289. Washingtonite, 334.- Y'ater, 519. Wavellite, 28. Websterite, 207. Y^ehrlite, ] 58. AA'eissite, 154. Y^ernerite, 16. YTiewellite, 518. Y^hite Antimony-ores family, 379-382. YlclitAme, 135. Y'illemite, 252. Y^iserin, 190. Y^ithamite, 133. Witherite, 197. Y'ittichenite, 471. Y^certhite, 137. Y^ohlerite, 173. Y^olcliite, 465. WolfacMte, 412. Y^olfram, 336. Wolfsbergite, 458. WoUastonite, 97. Y^od-opal, 3. AA^ilfenite, 313. Y'urzite, 474. Xaxthite, 132. Xantbokon, 482. Xantbo^^byllite, 75. Xenolite, 137. Xenotime, 190. XylocMor, 46. Yellow-earth, 111. Yellow-ochre, 332. Yenite, 158. Yttrocerite, 181. Yttroilmenite, 338. Yttrotantalite, 340. Yttrotitanite, 172. Zaratite, 295. Zeagonite, 57. Zeilanite, 147. Zeolite family, 38-60. Zeunerite, 292. Zeuxite, 155. Zinc, Xat, 400. Zinc, Carbonate of, 250. Red oxide of, 379. Silicate of, 251. Sulphate of, 224. Sulphur et of, 473. Zinc-blende, 473. Zinc-bloom, 250. Zincite, 379. Zinckenite, 448. Zircon, 143. Zoisite, 133«. Zundererz, 4S3. Zurlite, 21. Z^^ieselite, 256. Zygadite, 14. THE END. Printed by R. R. Ci-ARiv, Edinburgh. In fc]). 8vo, doth, pice bs. ELEMENTS OF ZOOLOGY FOE THE USE OF SCHOOLS AND SCIENCE CLASSES BY ANDKW WILSON. ILLUSTRATED WITH ONE HUNDRED AND FIFTY WOOD ENGRAVINGS. Edinburgh Medical Journal. The style is clear and easily read, and while a sufficient nnmber of examples have been given, the text is not overloaded with detail. The chief merit of the work is that any one reading it is not only put in possession of some facts in natural history, but is put in a position to carry out the study of the subject for himself in larger works. Upon the whole, we may congratulate the author upon having supplied a want, and written a book which, if nothing very great or original, is likely to be useful. Standard. It is admirably adapted for the purpose for which it is intended. The author, himself a lecturer on Zoology, had long felt the want of a book which should be at once constructed on scientific principles, and giving the outlines of science required, and yet free from the great practice of that technicality which so worries and disgusts young students. The most re- cent and best methods of classification have been adopted, and equal attention is given to the vertebrate and invertebrate forms. The work will be hailed alike by teachers and students, and parents will find it a most welcome gift-book for studious boys and girls who are always " wanting to know." Scotsman. A particularly handy book, convenient in shape. Written with re- markable conciseness, and carefully calculated for the wants of students v/orking in advanced classes. A most welcome book to a large number of students. Glasgow Herald. A valuable text-book for students in mastering the principles of a science which is now receiving much more attention than was bestowed upon it in the past. Edinburgli Courant. No better book can be placed in the hands of a young man desirous of entering upon a study which affords to the intelligent mind inexhaustible sources of delight. It is strictly what it professes to be, an elementary treatise, adapted for the use of schools and science classes, and takes in the whole field of Zoology, whilst a due proportion is assigned to each of the diff'erent parts. \_Over. 2 In fcp, Svo, doth, illustrated, price is. 6d. dUKES^S SCHOOL MANUAL OF GEOLOGY. NUTF EDITION, ^ Edited by ALFRED J. JUKES -BROWNE, St. Jolm's College, Cambridge. Quarterly Journal of Science. With the exception of the classic writings of Sir Charles Lyell, there are perhaps no modern text-books better known to the student than the Manuals of the late Professor Jukes. His were no mere compilations, as elementary treatises too often are, but were the w^ork of a field geologist, whose heart was in his hammer. The success of Jukes's larger volume, the "Students' Manual," induced the author, about ten years ago, to write an introductory work, under the title of the " School Manual of Geology.'* Since the lamented death of Professor Jukes, new editions of both works have been called for ; the editing of the larger Manual was entrusted to the author's colleague. Professor Geikie ; that of the smaller Manual to the author's nephew, Mr. A. Jukes-Browne, Since the original appearance of the "School Manual" geology has made great advances. But whilst duty to the reader has compelled the editor to effect many alterations, he has wisely forborne, from respect to his uncle's memory, to unnecessarily interfere with the original plan of the work. Jukes's "School Manual" remains, then, what it has always been — one of our best text-books for the student of elementary geology. Mining World. We have been highly pleased with a new edition of an elementary w^ork, "The School Manual of Geology," by J. Beete Jukes, Esq., M.A., F.R.S., edited by Alfred J. Jukes-Browne, Esq. Written for the express use of young persons, this work leads on gradually to the more abstruse portions of the subject, and prepares the student by easy degrees for works of more difiicult comprehension ; and whilst giving sufficient explanations of the different fauna which existed at each period, to make the general descrip- tions intelligible, must naturally awaken a desire not only to prosecute the inquiry, but also to acquire a knowledge of the kindred studies of botany, zoology, and mineralogy. In France an excellent series of elementary works on these topics by Jussieii, Milne Edwards, and Beudant, were pub- lished many years ago ; but apart from the difficulty of language, they were perhaj)s too technical and abstruse for the use of schools. In the book before us this latter defect has been avoided; and as to the mature reader Hugh Miller's old red sandstone is a rare treat, so to the younger it must prove a charming as well as highly instructive work. There is, perhaps, no uiore difficult task than to wi itc (\isily and M ith simplicity on a difficult subject, and to do so well rciiniros tlic most intimate knowledge of it. This Mr. Jukes was admirably u(laj)ted to do, and he carried to his task that love which rarely fails to find a res2)onse in the breast of youth. 3 Well illustrated, well printed, neatly bound, and of a convenient size, the " School Manual of Geology " is a fitting specimen of what such educa- tional works ought to be, and will no doubt be appreciated by all who have the interest of a general high -class education for the rising generation at heart. Mining Journal. The facility with which a sound knowledge of a science may be obtained, and the interest attaching to the study of it, is almost entirely dependent upon the character of the books whence the earlier introduction to the sub- ject is derived, and among the most interesting and instructive volumes issued the " School Manual of Geology," by the late Prof. J. Beete Jukes is certainly entitled to the prominent place which has ever been assigned to it. To keep the work well up to the knowledge of the day a second edition has just been completed by his nephew, with the assistance of the Rev. T. G. Bonney, Fellow of St. John's, Cambridge, and the additions and emendations have even increased the value of the book. It is remarked that in prepar- ing the new edition regard has been had to the great advance of geology and its associate sciences since the first appearance of the Manual, and that it has been found necessary to re-write some parts and to re-adjust several of the chapters. Mr. Jukes-Browne's endeavour has been to preserve as far as practicable the style and method of treatment pursued by the author, and to carry out as completely as he could his object in writing the work. The explanation of acids and bases contained in the fii'st edition has been wisely preserved as more easily explaining facts than more recent theories, and the classification of rocks has likewise been retained, partly because it is so kept in the third edition of the larger Manual to which the school edition forms a kind of introduction, and partly because he thinks it is easier to comprehend than any more elaborate arrangement. The general character of the "School Manual of Geology" is already well known to the readers of the " Mining Journal : " it directs the student's attention to geological operations at present going on around him, and which he can consequently examine for himself, and then explain the changes which these actions would in time bring about, accounting for the geo- logical features elsewhere observed. With regard to the earth as a whole, it is remarked that we can hardly avoid arriving at the conclusion that the interior of the earth is intensely hot. If we were to suppose that the in- crease of temperature went on at the same rate indefinitely into the interior as that which regulates it in our mines and wells, or even if we allowed that it increased at a slower rate, say for instance, 1° Fahr. for every 100 feet of descent, we should arrive very shortly at an intense temperature ; at 50 miles we should have a temperature sufficient to melt steel, and at 100 miles we should get a temperature equal to more than 5000 Fahr., which is a heat greater than any we know at the surface. It is not by any means necessary, however, to suppose that the temperature does increase inde- finitely into the interior, or that the rate which regulates its increase near the surface continues to be the same for such depths as those just mentioned. Neither does it follow that the materials, whatever they may be, which ex- ist at great depths, would be melted by the same heat that would fuse them at the surface, since the enormous amount of pressure which they must experience may keep them solid in spite of the heat. After chapters on volcanoes and earthquakes, there is an interesting one on rise and fall of ground, the conclusion arrived at concerning which is that 4 the crust of the earth, is in frequent, if not in constant, movement m some part or other ; lai^ge parts remaining stationary for long periods, while others are being elevated, and others agaia depressed. We know that the sea, with its present level, has once flowed over the spots now occupied by our loftiest mountaius. On the other hand, there is nothing improbable in the belief that land once existed where now the deepest pans of ocean ai'e to be found. Mr. Darwin observes of the earthquake which he felt at Valdivia in 1S35 : — " It was something like the movement of a vessel in a little cross-ripple, or still more like that felt by a person skating over thin ice which bends under the weight of his body. A bad earthquake at once destroys the oldest associations ; the world, the very emblem of all that is solid, has moved beneath om- feet like a cmst over a fluid." The geologist, as he pm^sues his studies, learns to generalise this feeling and to apply it to the whole crust of the earth duiing all geological time. He finds that it always has been as it now is, utterly unstable, rising here and falling there, with long slow undulations ever shifting imder the liquid ocean, and moving it fi'om place to place as parts of its old bed are lifted up above its surface, and new hollows formed by the sinking of other shores. An outline of chemical nomenclature is given to prepare the way for accounts and descrip- tions of minerals and igneous rocks, rocks formed of animals and plants, and mechamcally formed rocks. The following chapter, which is a summary of the prece'iiTig ones, concludes the first part. Tiie second pai't of the book explains the principal facts observable on the ciTLSt of the eaiTh, the structure of rock beds, inclined beds, bent or broken beds, denudation, unconiormability, metamorphic or altered rocks, concretions, and veil:.? an:l irssils, and their mode of occurrence ; and the rhiivl pait embrace^ :"-r l_:^::ry of the formation of the earth's crust, de- duced from the fa;:> :V;r:T:;;jle in it as interpireted by the processes now in operation. After tracing the various geological changes which have marked the several periods, it is remai^ked that the geological histoiy of the earth thus closes with the appearance of man extenninating races of animals, just as preceding races have been exterminated by other animals than man. If this history were to be made complete, it should include an account of the aqueous rocks that were deposited, the igneous rocks that were intruded or ejected, the preceding aqueous rocks that were altered or destroyed, the animals and plants that made their appearance and those that disappeared during each period of the history, and for eveiy large division of the globe. " Geologists were, before the appearance of Sir C. Ly ell's " Piinciples," mostly led away, for want of sufficient knowledge, into mere speculations as to what might have produced the earth's crust, instead of patiently studying the actions which were now operating in that produc- tioiu Hence arose such notions as that gi^anite was necessarily the most ancient of all rocks, and that after the formation of granite came that of gneiss, and so om It is true it is remarked that the spread of a cold climate seems to have been veiy general over the world during part of the pleisto- cene period ^though probably the glacial epochs in the northern and southern hemispheres may not have been s^Tichronous) and to have formed a marked expression to the meteorological conditions that had pre^iously prevailed. During former periods the climate of the whole earth seems to have been more genial and more equable than it is now. The change, how- ever, seems to have been a gradual one, both in its incoming and in its outgoing, and a mere extension to lower latitude of the climate which re- mains now in the polar regions of the earth. However it may have been 5 caused, we do not find here or elsewhere in the history of the earth any evidence of an abrupt termination of one order of things, and a sudden in- troduction of another. Few and scanty and broken as are our records of the past, they contain far more evidence of the slow and gradual and continuous action of the natural forces than of rapid or capricious or intermittent change. The present day is linked indissolubly with all past time, and that which we see around us is the result of that which has been before. Whether considered as a separate text-book, or as an introduction to the larger Manual, this volume is worthy of high commendation. It con- tains an abundance of information of a thoroughly reliable character, and although the outline necessarily leaves many details to fill in, the student will have nothing to unlearn, and will learn nothing that is useless to him. Popular Science Review. Mr. Jukes-Brovme's little book is a capital introduction to geology. It V7as, even when it was first brought out by the late Professor Jukes him- self, an excellent work ; and now the editor has taken so much trouble, and has exercised such judicious skill in the direction of his amendments, that the volume is for the present date as good a book as it unquestion- ably was when it first appeared about ten years since. Parts of some chapters have been quite re-written, and others have been modified in accordance with the changes that the science has undergone since. But it seems to us that the editor very wisely left the chemical part as it was. So many systems are now in vogue, and it is so impossible to say which will eventually hold its own against its compeers, that a wise discretion was shown in the maintaining of this section as in the old book. The general plan has not been altered, but many woodcuts have been intro- duced, and the entire work has been brought down to 1873 with skill and discretion. On the whole, we are very much pleased with this second edi- tion, and we wish it what it deserves — a very good sale. JUKES'S G-EOLOGY-lsrEW EDITION BY GEIKIE. Now ready, in crown 8vo, price 12s. 6d. The Student's Manual of Geology. By J. BEETE JUKES, M.A., F.R.S., Late Director of the Geological Survey of Ireland. Third Edition, Kecast, and in great part Rewritten. Edited by ARCHIBALD GEIKIE, F.R.S., Director of the Geological Survey of Scotland, and Regius Professor of Geology and Mineralogy in the University of Edinburgh. Illustrated by 166 Figures and 47 Fossil Groups. 6 In one vol. royal Svo, pp, 1117, with 1800 Illustrations, pice 21 5. CLASS-BOOK OF BOTANY. Being an Introduction to the Study of the Vegetable Kingdom. By J. HUTTON BALFOUE, M.D., F.E.S., Professor of Medicine and Botany in the University of Edinburgh, and Regius Keeper of the Royal Botanic Garden. (May also he had in two ^oarts^ ])™^ 2\s) " In Dr. Balfour's ^ Class-Book of Botany/ the author seems to have exhausted every attainable source of information. Few, if any, works on this subject contain such a mass of carefully collected and condensed matter, and certainly none are more copiously or better illustrated." — Hooker'' s Journal of Botany. " Professor Balfour's ^ Class-Book of Botany ' is too well and favourably known to botanists, whether teachers or learners, to require any introduction to our readers. It is, as far as we know, the only work which a lecturer can take in his hand as a safe text-book for the whole of such a course as is required to prepare students for our University or medical examinations. Every branch of botany, structural and morphological, physiological, systematic, geographical, and palseontological, is treated in so ex- haustive a manner as to leave little to be desired. " The work is one indispensable to the class-room, and should be in the hands of every teacher." — Nature. " The voluminous and profusely illustrated work of Dr. Bal- four is too well known to need any words of comment." — Lancet. 7 WOEKS BY SIE J. F. W. HEESCHEL, BAET, K.H., &c. &c. 1. In crown Svo, doth, Third Edition, price 5s. PHYSICAL GEOGRAPHY OF THE GLOBE. Contents— The Sea— The Land— Eivers— Springs— Caves- Plains — Climate — Eain —Thunderstorms— Hurricanes and Earthquakes — Terrestrial Magnetism — Mineral Products Gems — Salt— Coal — Sulphur— Plants — Animals — Fossil Eemains — Ethnology, etc. "An>dmirable Manual of the whole science/'— British Quarterly Review, ^ ^ "It is utterly impossible to give an account of the immense amount of information so admirably and lucidly compressed in the volume before us." — London Review. II. In f cap. Svo, cloth, pice 3s. 6d. METEOROLOGY. Contents— Air— Altitudes— Aurora Borealis— Balloon Ascents — Barometer — Barometri c Pressures — Climate — Clouds Cold— Currents — Cyclones — Density of Air — Dew Dry- ness — Dust — Electricity — Evaporation — Fogs — Frosts Gulf Stream— Hail— Heat— Hoar Frost— Humidity— Hur- ricanes —Ice — Icebergs — Kite, Electrical — Lightning— Meteorolites— Monsoons — Ocean — Eain — Rainbow— Sea- sons — Snow — Sun — Temperature — Thunder — Tides Vapour — Wind, etc. As text-books for Colleges and School use, on the subjects on which they respectively treat, there is nothing in the whole range of our educational literature which can at all be compared with ihem." —Educational Times OWEN'S PAL/EONTOLOGY. In Svo, Second Edition, with Index and Glossary, and Illustrated with nearly Tivo Hundred Wood Engravings, price 7s.'6d. PAL/EONTOLOGY; Or, a Systematic Summary of Extinct Animals and their Geological Eelations. By EICHAED OWEN, F.E.S., Superintendent of the ITatural History Departments in the British Museum. *'iVo 07ie vjith any . 20Tetensions to science should he without Oweii's Palceontology.'' — Lancet. * ' The Prince of Palceontologists has here iiresented us with a most comjprehensive survey of the characters^ succession, geological j^osition, and geographical distribution of the various forms of life that have 2^cissed ctway.'' — Medical Times and Gazette. Uniform with " Jukes's School Geology." In fcap. Svo, with 427 TFood Engravings, price 3s. 6d. ELEMENTS OF BOTANY By J. HUTTON BALFOUR, M.D., Professor of Medicine and Botany in the University of Edinburgh. EDINBURGH : ADAM AND CHARLES BLACK.