COPYRIGHT, 1916, 
 
 BY 
 
 JOHN WILEY & SONS, INC. 
 
 
 Stanbopc flbreas 
 
 F. H. GILSON COMPANY 
 BOSTON, U.S.A. 
 
PREFACE 
 
 ANALYSIS, that valuable tool of Science, can obviously be used 
 only when the basal elements or units are recognized and under- 
 stood. In geologic science it was early realized that a far 
 greater insight into the character and significance of rocks than 
 that afforded by their bulk composition is gained by knowledge 
 of the kinds and proportions of their constituent minerals, which 
 stand in relation to geology much as do the elements to chemistry. 
 In consequence, mineralogy changed from an engaging phase 
 of the collecting mania to a fundamental requisite in our study of 
 the rocks, and microscopic petrography evolved as its specialized 
 application to these natural associations of the minerals, whereby 
 understanding of the nature and origin of materials forming our 
 planet has been greatly extended. 
 
 One class of geologic bodies, the ores, relatively neglected in 
 earlier stages of geologic advance, have of late years received in- 
 creasing attention, partly because of their inherent interest, 
 partly because they so sensitively record as to illuminate many 
 complex geologic processes, but above all because of their enor- 
 mous economic importance. Microscopic study of ores, however, 
 was on a basis now known to be one-sided and inadequate, until 
 application of the reflecting microscope, virtually beginning with 
 Campbell's paper in 1906, permitted as minute and satisfactory 
 observation of the opaque, metalliferous minerals, as had long been 
 possible for the transparent varieties. This new method, quickly 
 adopted by numerous American investigators, has already demon- 
 strated its immeasurable value and is rapidly disclosing new 
 and unsuspected truths regarding the opaque minerals. Indeed, 
 it opens an entire new field of geologic science that promises to 
 do for the ores what petrography has done for the rocks; for 
 this the name " Mineralography " is herein proposed. 
 
 One serious handicap, lack of adequate means for identifying 
 the mineral varieties, has hindered the fullest development and 
 delayed wider adoption of this new method. Several lists of 
 
 iii 
 
 340247 
 
iv PREFACE 
 
 properties of certain minerals and one or two essays at more 
 systematic identification have appeared. However, the necessity 
 for completeness, emphasized by Dana, for mineral determina- 
 tion in general, is even greater for the opaque varieties, owing 
 to the closely similar properties of many. In other words, no 
 determinative scheme for the opaque minerals can be satisfactory 
 or reliable unless it includes them all. It cannot be concluded, 
 for example, that a given mineral grain is tetrahedrite, because 
 in certain tests it behaves like that species it is necessary to 
 prove that the grain in question actually ia tetrahedrite and not 
 something else, such as bournonite or polybasite, which closely 
 resemble it in many ways; even the probabilities of the case 
 cannot be relied upon, for it is now evident that many supposedly 
 rare minerals are actually rather common in sulphide ores, are 
 often of important geologic significance, and can in no case be 
 safely ignored. 
 
 The scheme of determination of opaque minerals here presented 
 embraces nearly every species of recognized identity that could be 
 secured from the principal mineral collections of the United States, 
 and thus includes many names probably familiar only to the pro- 
 fessional mineralogist. One, who, like the geologist of a mine, 
 may wish simply to examine the intimate relations of the minerals 
 in a familiar ore, might therefore conclude that this treatise is 
 too purely scientific and detailed for the needs of a busy, prac- 
 tical man. But he may be assured that even the simplest sulphide 
 ore is more than likely to hold unsuspected constituents whose 
 identity and significance, when determined, may prove of direct 
 value. 
 
 Nor is specialized training or technique a pre-requisite to intelli- 
 gent use of this plan of identification. Intricacies of crystallog- 
 raphy and optics, essential to thin-section petrography, and 
 generally mastered only under expert instruction, are not here 
 involved; absence of the diagnostic optical properties of trans- 
 parent minerals is balanced by ease of applying physical and 
 chemical tests to the polished surface; even the microchemical 
 reactions need not be understood to be used correctly. Prac- 
 tically the only requirement is to follow the simple directions 
 indicated and the plan of indexing employed will lead almost 
 automatically to the proper result. The entire scheme may be 
 mastered by any one possessing common sense and a good eye. 
 
PREFACE V 
 
 In the matter of equipment, likewise, the demands are modest. 
 Though elaborate instruments are advisable under certain cir- 
 cumstances, satisfactory results may be secured with the simplest 
 outfit. Almost any microscope, for whatever purpose designed, 
 may be adapted for this study at slight expense by attaching a 
 prism reflector that permits Daylight illumination. Or a satis- 
 factory microscope may be had complete for less than $30.00. 
 Mounting clay, glass tubing, and a few reagents complete the 
 necessary equipment for examination, while the specimens may 
 be prepared without delay by means of a file, emery cloth, chamois 
 skin and rouge, if better means are not at hand. For the opaque 
 minerals this determinative method should in time largely sup- 
 plant blowpipe analysis, since it can in most cases yield better 
 and quicker results with equal or greater simplicity, and perhaps 
 as cheaply, if widely adopted. 
 
 Notwithstanding its fitness for elementary and for practical 
 determinative uses, this text is intended equally for serious re- 
 search. Mineralographic methods show that to a far greater 
 degree than is true of the transparent species, the sulphide min- 
 erals tend to be microscopically mingled and intergrown in most 
 intimate fashion, also that they may undergo serious alteration 
 of which no outward sign may exist. In consequence, the compo- 
 sition ascribed to many species is discredited, the right to stand 
 as independent species is disproved for others, and new species 
 as yet unnamed have appeared, even in specimens from the 
 best-known collections of the country identified unquestionably 
 with the greatest accuracy possible hitherto. In short, the min- 
 eralogy of the sulphides needs complete revision. Henceforth, 
 he who describes or analyzes an opaque mineral, without first 
 establishing its purity by closest mineralographic scrutiny, dis- 
 counts his own reliability and that of his results. 
 
 In more practical directions, the wide applicability of this method 
 of mineral investigation may be indicated by a list of typical problems 
 it has solved in materials submitted to the Harvard laboratories: 
 
 (a) Method of occurrence and state of combination of gold, 
 silver and other metals in ores as affecting choice of treatment 
 to be adopted. 
 
 (6) Condition of metals lost in mill tailings (up to 100-mesh 
 powders) and in slags, that suitable improvements in recovery may 
 be applied. 
 
Vi PREFACE 
 
 (c) Extent and effect of roasting and of subsequent leaching 
 of sulphide-bearing tailings from concentration. 
 
 (d) Character of furnace mattes, whether homogeneous or 
 complex. 
 
 (e) Various practical geological problems difficult or impossible 
 of solution otherwise, such as determining whether metal values 
 in churn-drill pulps are primary or are due wholly or in part to 
 secondary enrichment; also distinction between primary and 
 secondary chalcocite. 
 
 The investigation embodied in this book originated as one of 
 the essential preliminaries to a study of mineral occurrence and 
 alteration being carried on by the Secondary Enrichment Inves- 
 tigation. It has been steadily pursued by Dr. Murdoch since 
 1911 and has had the benefit of trial in actual practice by members 
 of the Secondary Enrichment staff and in the Harvard labora- 
 tories during the last two years, also in the Geological Depart- 
 ment of the Massachusetts Institute of Technology during the 
 past year. 
 
 L. C. GRATON. 
 
 CAMBRIDGE, MASS. 
 August, 1915. 
 
CONTENTS 
 
 PAGE 
 
 FRONTISPIECE '. 
 
 PREFACE iii-vi 
 
 INTRODUCTION 1 
 
 HISTORY 1 
 
 IMPORTANCE OF THE SUBJECT 3 
 
 PREVIOUS WORK 4 
 
 SCOPE OF PRESENT WORK 14 
 
 BIBLIOGRAPHY 16 
 
 TECHNIQUE OF MINERALOGRAPHY 19 
 
 POLISHING 19 
 
 MOUNTING 23 
 
 EXAMINATION 24 
 
 MAGNIFICATION 25 
 
 PHOTOGRAPHING 25 
 
 COLOR COMPARISON 26 
 
 HARDNESS DETERMINATION 29 
 
 MlCROCHEMICAL TESTS 30 
 
 METHOD OF APPLICATION 30 
 
 REACTIONS 31 
 
 REAGENTS 32 
 
 MINERAL COMPOSITION AND IDENTITY 33 
 
 OBSERVED MIXTURES 36 
 
 PROBABLE MIXTURES AND DOUBTFUL MINERALS 38 
 
 PLAN OF CLASSIFICATION 40 
 
 COLOR 40 
 
 COLORED 40 
 
 WHITE 40 
 
 GRAY 41 
 
 TRANSPARENT AND GANGUE MINERALS 41 
 
 EFFECT OF SURFACE ON COLOR 42 
 
 HARDNESS 42 
 
 MlCROCHEMICAL TESTS 42 
 
 EXPLANATION OF TABLES 42 
 
 DIRECTIONS FOR USE 42 
 
 EXAMPLES 43 
 
 ' CROSS-REFERENCES 44 
 
 ABBREVIATIONS 45 
 
 OUTLINE OF THE CLASSIFICATION 47 
 
 TABLES FOR MINERAL IDENTIFICATION 57-152 
 
 MISCELLANEOUS TABLES 153 
 
 CONDENSED DETERMINATIVE TABLE 154 
 
 ODOR AND STREAK OF MINERALS 156 
 
 MINERALS TABULATED BY ELEMENTS 157 
 
 INDEX OF MINERALS 163 
 
 vii 
 
MICROSCOPICAL DETERMINATION OF 
 THE OPAQUE MINERALS 
 
 * INTRODUCTION 
 
 HISTORY 
 
 THE microscope was first applied to the study of thin sections 
 of transparent minerals in 1828 by Nicol, 41 but the first prac- 
 tical use of it in studying thin sections was made in 1851 by 
 Sorby. 40 This method of investigation has now been brought 
 to a high point of efficiency and perfection. By means of the 
 petrographic microscope, transparent minerals can be identified, 
 and their most minute relationships observed, so that this instru- 
 ment has gone far towards solving many of the important prob- 
 lems connected with ore and rock genesis, mineral constitution 
 and alteration. The ordinary petrographic microscope is thus 
 entirely satisfactory for the study of minerals which appear 
 transparent in thin section, but, for the following reasons, loses 
 much of its value when applied without modification to the study 
 of ores, in which most of the important minerals are opaque. 
 
 In grinding a thin section, one of the fundamental requisites is 
 to secure a plate of uniform thickness, as nearly plane as possible 
 on both sides, with no difference in relief developed between 
 hard and soft minerals. In this way comparison, which would 
 not be possible otherwise, may be made of the different optical 
 properties of minerals. But even with modern methods of prep- 
 aration, if the surface is ground so that the harder minerals are 
 perfectly smooth and shiny, the softer ones will be polished out, 
 and the section will go to pieces; consequently the best that 
 can be done in producing the plate of uniform thickness is to leave 
 its surface microscopically rough. When observed by means of 
 reflected light, the opaque minerals in such a section appear so 
 rough that only the larger relations are usually apparent and they 
 reflect in the desired direction so little light, that it is frequently 
 
 Note. The determinative tables of this book, in practically their present form, con- 
 stitute the principal portion of a thesis presented as part of the requirement for the 
 degree of Doctor of Philosophy at Harvard University. 
 
2 MICROSCOPICAL DETERMINATION 
 
 difficult or impossible to differentiate between closely similar 
 minerals, without some further means of testing. Moreover, 
 with vertical illumination, the coverglass on a thin section reflects 
 much of the light before it reaches the section, so a dim image is 
 produced, and the difficulty of accurate observation is increased. 
 Until recently, however, most microscopic investigation of the 
 sulphide minerals has been accomplished in this way. 
 
 In 1814, Berzelius 6 polished a section of pyrrhotite, in the hope 
 of ascertaining why the composition was variable, and found 
 another sulphide intergrown with it, showing a different color. 
 He does not mention using a microscope in this examination. In 
 1863, Sorby 40 published an account of the microscopic examination 
 of polished surfaces of iron. His methods of examination were 
 practically those use.d today by metallographers, though of course 
 the apparatus and methods of polishing have since been improved. 
 This marked the beginning of the science of metallography, but 
 the method was not applied to the examination of opaque minerals 
 until 1885, when Baumhauer 4 polished some bornite and noted 
 microscopically admixed chalcocite, chalcopyrite and galena, and 
 gave some micro-drawings of the sections. Then, in 1887, A. A. 
 Julien, 21 in studying pyrite, examined the smooth and etched 
 natural surfaces of crystals with the Sorby reflecting microscope. 
 He did not artificially polish any of his specimens. In 1904, E. 
 Hussak 19 studied microscopically some polished surfaces of titanif- 
 erous magnetite from Brazil, and also etched and photographed 
 them. 
 
 About 1900, William Campbell, a metallurgist, polished and 
 examined under the metallographic microscope, some specimens 
 of natural pyrrhotite in order to ascertain, if possible, the cause 
 of their magnetic quality; he was at once so much impressed 
 with the possibilities of this method for the study of opaque 
 ores, that he determined to pursue the subject further. In 1906 
 he published a paper 12 describing rather fully the application 
 of metallographic methods to opaque minerals, giving details 
 of manipulation and examination of specimens. This paper, 
 in which for the first time was emphasized the extreme value 
 to the geologist and mineralogist of the method so successfully 
 employed for metals and alloys, may be said to mark the be- 
 ginning of the serious application of the reflecting microscope to 
 opaque ores. Though Campbell's paper attracted a considerable 
 
 t < , , 
 
OF THE OPAQUE MINERALS 3 
 
 amount of attention at the time of its publication, for several 
 years following little was published involving the use of this 
 method. More recently there has been rapidly increasing evi- 
 dence of the use of this means of examination by students of 
 mining geology, though its practice is still mainly confined to 
 this country. 
 
 IMPORTANCE OF THE SUBJECT 
 
 The examination of opaque minerals and ores by the reflecting 
 microscope is now established as a definite branch of geologic 
 investigation, and merits a designation of its own. For this, the 
 term " mineralography " is suggested; it is analogous to " pe- 
 trography," which now commonly implies the microscopic study 
 of rocks, and to " metallography," the microscopic study of 
 metals and alloys, while its etymology signifies its relation to 
 the broad science, mineralogy, as petrography is related to the 
 more inclusive subject, petrology. The possible objection that 
 the subject is really narrower than its name implies, since it deals 
 with only one division of minerals, is also applicable to crystal- 
 lography, which does not claim to usurp the entire field of crystal 
 study, and to metallography, which deals only with certain 
 features of metals; and indeed, it is because petrography has in 
 practice been limited to less than its name implies, that there is 
 room and need for this new subject, mineralography. Petrog- 
 raphy and mineralography are complementary, and together 
 will cover both the rocks and the ores. 
 
 By the methods of mineralography the appearance and struc- 
 tures of opaque minerals can be observed as accurately and easily 
 as those of transparent species in the ordinary thin section. 
 Mining geologists are beginning to realize that the careful micro- 
 scopic study they have been giving to the transparent gangue 
 minerals in ores yields only a part of the information required, 
 and that it is necessary to gain equally detailed and accurate 
 knowledge concerning the microscopic relations of the opaque 
 minerals, which are, in fact, the most important constituents of 
 most ores. It is in this direction that the subject will find its 
 widest economic application. 
 
 Mineralography should also be of the greatest assistance to 
 the mineralogist, in determining the purity of opaque minerals. 
 Examination of several thousand ore and mineral specimens shows 
 
4 MICROSCOPICAL DETERMINATION 
 
 that even well-crystallized material is commonly very impure 
 and quite unsuited for accurate determination of mineral compo- 
 sition. To secure a few grams of even the common sulphide 
 minerals unmixed with other species usually requires long search; 
 rarely does a polished surface a centimeter square show the 
 presence of only one constituent. It also has been shown that the 
 variable composition or doubtful character of a number of minerals 
 is due to mechanical mixture of two or more constituents, and 
 undoubtedly others will be similarly explained. Accordingly, 
 there is imperative need for mineralographic examination to 
 accompany chemical investigation of the opaque minerals, because 
 without it, the significance of the analysis must be in doubt. 
 Besides, it will save the time and expense of analysis of material 
 that is in reality impure. 
 
 This branch of geologic science is undoubtedly one of great 
 promise, capable and worthy of development to a high point of 
 efficiency, and comparable in value to the study of transparent 
 minerals by the petrographic microscope. 
 
 Before any conclusions can be drawn from the study of a pol- 
 ished section it is absolutely essential to be able to identify the 
 minerals it contains. As yet, however, no comprehensive sys- 
 tematic scheme of opaque mineral identification has been published, 
 and accordingly each investigator has had to work out his own 
 problems in identification, with little help from others. It is 
 clear from the fact that various minerals are mentioned in papers 
 dealing with mineralographic descriptions, that the writers have 
 devised some means of identification, but in most cases these are 
 not given, and undoubtedly some determinations have been 
 erroneous. 
 
 PREVIOUS WORK 
 
 The following paragraphs briefly summarize all the published 
 data on opaque mineral identification found in careful search 
 through the literature. 
 
 1814. Berzelius 6 sliced and polished pyrrhotite, and observed 
 that it was veined through by a different colored mineral, so that 
 he could distinguish the two by their colors. He did not use a 
 microscope. 
 
 1885. Baumhauer 4 noted the importance and desirability of 
 microscopic examination of polished surfaces of opaque minerals 
 in reflected light, since meteorites had been successfully studied 
 
OF THE OPAQUE MINERALS 5 
 
 in that way. He examined polished sections of massive bornite 
 from Chloride, N. M., and saw many included areas of bluish 
 gray chalcocite. He developed different crystal grains in the 
 bornite by etching a short time with HNOa, and also observed 
 that the chalcocite, etched a short time with concentrated HN0 3 , 
 developed " a kind of striation" having different directions in 
 different grains. Some areas etched more deeply than others. 
 He noted that chalcocite was as hard as bornite, and showed 
 no cleavage. He also noted a little chalcopyrite, but did not 
 describe its characteristics, and certain areas of a mineral whiter 
 than chalcocite, full of triangular pits, which he suggested might 
 be galena, but about which he would not commit himself. It is 
 clear from his description and drawing that it was really galena, 
 as the characteristics he describes are conclusive and his drawing 
 confirms these. 
 
 1887. l Julien 21 described the appearance of crystal faces of 
 pyrite. 
 
 1897-8. Beijerinck 5 wrote a very important paper on the 
 electric conductivity of minerals, especially the opaque varieties. 
 He sometimes used polished surfaces to give the " pattern " of 
 impurities on a gelatine plate, formed by local electric currents 
 set up by the differences of potential of the different minerals. 
 He said that he discovered impurities in his material this way. 
 He did not, however, study these polished sections with the 
 microscope. 
 
 1904. Hussak 19 polished titaniferous magnetite, etched it with 
 strong HC1, and thereby developed a distinction between ilmenite, 
 which did not blacken, and magnetite, which did. 
 
 1906. Campbell 12 suggested the possibilities of identification 
 by different reagents, and by different colors and appearances of 
 minerals. 
 
 - Campbell and Knight 13 described the appearance of niccolite, 
 smaltite, argentite, silver, and two unknown minerals, from Cobalt, 
 Ontario, but gave no record of tests. 
 
 1907. Campbell and Knight 14 summarized briefly a few -char- 
 acteristics of the Sudbury ore minerals as follows: 
 
 Chalcopyrite. Clear yellow color. Takes a good polish. 
 H. - 4. 
 
 Its color is its chief distinguishing characteristic. 
 
6 MICROSCOPICAL DETERMINATION 
 
 Magnetite. Steel gray color. Polishes very well* but 
 more slowly than chalcopyrite. H. = 5.5 6.5. It etches 
 differentially along cleavage planes, often yielding a " grid- 
 iron " structure. 
 
 Pentlandite. Light bronze color. Polishes better than 
 pyrrhotite; is not so brittle. H. = 4. Sometimes shows a 
 distinct cleavage. Easily distinguished from pyrrhotite by 
 etching. 
 
 Pyrite. Pale brass color. Polishes with difficulty. 
 Retains scratches long after other constituents. H. = 6 - 
 6.5; therefore it polishes in relief. 
 
 Pyrrhotite. Light bronze color, similar to pentlandite. 
 More brittle than pentlandite and shows a more pitted 
 surface. H. = 4. By immersing in hot HC1 (1 acid to 1 
 water) pyrrhotite is attacked, pentlandite is not. 
 
 1908 Simpson 37 summarized the characters of a few minerals 
 as follows: 
 
 Bornite. Copper red to pinchbeck brown in color. 
 H. = 3. Easily attacked by nitric acid. This acid gives 
 the bornite a tarnished appearance. When with pyrite, an 
 extremely smooth surface of this mineral is difficult to 
 obtain, on account of the great difference in hardness be- 
 tween the two.- 
 
 Chalcocite. Blackish lead gray in color. H. = 2. 
 When etched with nitric acid, a distinct blue color is ob- 
 tained. This is the best means of identification. 
 
 Chalcopyrite. Color, brass yellow. H. = 3.5 4. The 
 color is the best characteristic. Soluble in nitric acid. 
 
 Enargite. Color steel gray to grayish black. H. = 3. 
 Soluble in Aqua Regia only. Its insolubility in nitric 
 acid is the best means of distinguishing it from chalco- 
 cite. 
 
 Pyrite. Its pale brass yellow color is one of the best 
 means of identification. On account of its hardness, it 
 retains scratches long after the other constituents. H. = 6 
 - 6.5. Etched by nitric acid. 
 
 * Probably because in the Sudbury ores, magnetite is present in small grains in a 
 softer matrix. 
 
QLO 
 
 OF THE OPAQUE MINERALS 7 
 
 These colors were apparently taken by Simpson from the 
 descriptions in a text-book on mineralogy, and do not in all cases 
 represent the colors on the polished surface. 
 
 - Warren 44 described briefly the appearance of magnetite and 
 ilmenite (in titaniferous magne.tite) etched by strong HC1, and 
 unetched, saying that the ilmehite appeared as bright gray, narrow 
 strips, and the magnetite as duff black. 
 
 - Koenigsberger 22 devised a method for observing the optical 
 character of opaque minerals in reflected light. He used a re- 
 flecting prism for a vertical illuminator, and employed a Savart 
 plate of calcite, a movable plate of plane glass and one nicol. 
 The magnification recommended was about 100 diameters. The 
 apparatus was adjusted with an isotropic metallic mirror so that 
 the Savart bands were not visible when the glass plate was hori- 
 zontal, but appeared when this was rotated vertically through 
 a large angle. Isotropic minerals behave like the glass, but 
 anisotropic minerals show the Savart bands, with four positions of 
 extinction and four of greatest brightness, as the stage is rotated. 
 His claims are as follows: He could distinguish the relation be- 
 tween optic and crystal symmetry by means of a contrast plate 
 attached in front of the prism illuminator. By the determina- 
 tion of extinction angles on oriented sections, he could discriminate 
 between monoclinic and orthorhombic minerals. If a mineral is 
 weakly anisotropic, it may be confused with isotropic minerals. 
 Some minerals are isotropic for one color of light, and not for 
 another. He could tell whether or not symmetry is reached by 
 hidden twinning. When crystal faces are not available, isotropism 
 or anisotropism can be determined more easily this way than by 
 study of any physical properties. He found that a basal plate 
 of molybdenite was isotropic. Hematite, pyrite, chromite, frank- 
 linite, argentite and tetrahedrite are also isotropic on basal sec- 
 tions. Pyrrhotite, parallel to the base, is made up of feebly 
 anisotropic parts. Glaucodot is feebly anisotropic perpendicular 
 to the vertical axis; chalcopyrite is strongly anisotropic. Chalco- 
 cite is isotropic on the base. Manganite, columbite, hematite and 
 ilmenite are quite strongly anisotropic. 
 
 For a fuller description of Koenigsberger 's apparatus and 
 methods the reader is referred to his paper, 22 or the translated 
 abstract in Winchell's Optical Mineralogy. 46 He laid great stress 
 on the necessity of very careful and perfect polish, and recom- 
 
8 MICROSCOPICAL DETERMINATION 
 
 mended chrome oxide for the final polish. Little success appears 
 to have attended the trial of this method in this country and the 
 validity of some of his premises is not universally accepted. 
 
 191 i. Laney 24 etched chalcocite with nitric acid, and devel- 
 oped cleavages in it, which he suggested were prismatic and basal. 
 Lee 26 investigated a number of minerals on the polished surface, 
 and gave an elaborate table of tarnish colors and coatings formed 
 by various reagents. His plan involved etching the whole speci- 
 men, and moreover it appears that he was unable to secure a good 
 polish on his minerals, so that the difficulty of identification, 
 especially of small areas, seems too great for practical use of his 
 methods. Below is given a list of the minerals studied by Leo. 
 
 Pyrrhotite Pyrite Barnhardtite [mixture] 
 
 Pentlandite Marcasite Linnaeite 
 
 Millerite Bornite Cubanite [mixture] 
 
 Horbachite Chalcopyrite Polydymite 
 
 - Lincoln 27 gave a valuable table for the identification of gold 
 minerals and some associated minerals. This table is reproduced 
 on the following page. 
 
 1912. Bastin 2 mentioned galena, chalcopyrite, sphalerite, 
 pyrite, polybasite, proustite and stephanite, but does not give 
 determinative criteria for all. He noted the triangular pits in 
 galena, and gave the following characteristics of polybasite. 
 " The freshly polished surface (of polybasite) has much the ap- 
 pearance of chalcocite . . . but unlike chalcocite it does not 
 tarnish or etch readily when treated with HN0 3 . When treated 
 with concentrated HN0 3 , a tarnish begins to appear on this 
 mineral at about the same time that it appears on the chalcopyrite 
 of the ore. When the chalcopyrite shows a faint peacock tarnish 
 the polybasite exhibits a yellowish brown color, in places showing 
 slight iridescence. In specimens where the polybasite is present 
 in too small amounts to be isolated, it may be identified in the 
 polished section by this characteristic behavior with HN0 3 ." 
 
 - Singewald 38 said that on the polished surface etched with hot 
 HC1, ilmenite appears bright and unaltered, and magnetite is some- 
 what dull black. 
 
 -Brunton 10 described the same minerals as Singewald. He 
 could see no difference on the unetched surface between ilmenite and 
 magnetite. He also polished rutile, and said it has a reddish tinge. 
 
OLO 
 
 OF THE OPAQUE MINERALS 
 
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10 MICROSCOPICAL DETERMINATION 
 
 1913. Graton and Murdoch 17 gave a brief account of the sig- 
 nificance of the commoner sulphides in ores of copper, with no 
 attempt to give other determinative characteristics than are 
 implied by manner of occurrence. 
 
 1914. Thompson 41 described the appearance of the following 
 minerals. 
 
 Chalcopyrite, smooth, bright brass color. 
 Pyrrhotite, generally pitted, distinctive light bronze. 
 Galena, dazzling white. 
 Sphalerite, smooth, blue. 
 Chalcocite, etched by nitric acid. 
 
 Tetrahedrite ] ... 
 
 \ no criteria given. 
 Bornite j 
 
 -Bruce 9 has assembled a number of tests made by pre- 
 vious investigators, and has added a considerable number made 
 by himself. In addition he gave brief notes on manipulation 
 and chemical tests, and listed a few reactions for elements, as 
 follows : 
 
 Iron. Fresh K 4 Fe(CN) 6 + acid gives deep blue. 
 
 Nickel. First a mixture of HNO 3 and tartaric acid is applied, 
 and allowed to evaporate, then touched with a drop of dimethyl- 
 glyoxime, freshly made ammoniacal, which gives a brilliant red. 
 
 Copper. A mixture of HNO 3 and K 4 Fe(CN) 6 gives a deep red. 
 With iron present, also, this is followed by green. 
 
 Manganese. Most manganese minerals are soluble in HC1, 
 giving a deep brown solution, which is rendered colorless by 
 addition of H 2 2 . 
 
 Silver. First HNO 3 , which is allowed to evaporate, then is 
 touched with HC1, giving a white precipitate. Lead and mercury 
 minerals give the same. 
 
 Bismuth. First HN0 3 , evaporated, then HC1 added. Then 
 water is added, producing a white precipitate. 
 
 Bruce's table of tests is given below. 
 
 I. MINERAL BY INCLINED ILLUMINATION is YELLOW. 
 
 A. Etched by HC1. 
 
 Pyrrhotite. Bronze yellow. Surface rough. Reacts for Fe. 
 
 B. Etched by HN0 3 , not by HC1. 
 
 (a) Without noticeable tarnish or deposit. 
 Pyrite. Pale yellow. Slightly rough. Reacts for Fe. 
 
OF THE OPAQUE MINERALS 11 
 
 Marcasite. Pale yellow. Slightly rough. Reacts for Fe. 
 
 Precipitates Ag (?). 
 
 Millerite. Slightly rough*. Reacts for Ni. 
 (6) With tarnish. 
 Chalcopyrite. Deep yellow. Rough. Reacts for Fe and Cu. 
 
 Iridescent tarnish. 
 C. Not attacked by single acids. 
 
 Gold. Deep yellow. Smooth. Amalgamates with Hg. 
 
 II. MINERAL is WHITE 
 
 A. Etched by HC1. 
 
 B. Etched by HN0 3 . 
 
 (a) With no tarnish or deposit. 
 
 Smaltite. Rough with bright facets. Gives Ni test. 
 
 Arsenopyrite. Rough with bright facets. Becomes gray with 
 reddish spots. Reacts for Fe, not for Ni. 
 
 Leucopyrite.* White. Very rough. Reacts for Fe. 
 
 Silver. Smooth. Reacts for Ag. 
 
 Bismuth. Smooth. Reacts for Bi. 
 (6) With deposit. 
 
 Arsenic. Chalky white deposit. 
 
 Antimony. Chalky white deposit. 
 
 C. Unattacked by single cold acids. 
 
 Cobaltite. Slightly rough. Etched by HNO 3 . 
 Niccolite. Slightly rough with reddish tinge. Treated with 
 Aqua Regia reacts for Ni. 
 
 III. MINERAL is BLACK OR GRAYISH BLACK 
 
 A. Etched by HC1. 
 
 Magnetite. Shows intersecting parting planes. Etches easily. 
 Fe reaction. 
 
 Franklinite. Fairly smooth. Etches less readily than mag- 
 netite. 
 
 Ilmenite. Fairly smooth. Etches very slowly. 
 
 Hematite. Steel gray. Smooth. Red streak. 
 
 Manganite. Dull black. Brown solution. 
 
 Psilomelane. Brown and black areas. Brown solution. 
 
 Braunite. Black. Etches to bluish black. Brown solution. 
 
 * Same as lollingite. 
 
12 MICROSCOPICAL DETERMINATION 
 
 Alabandite. Smooth, grayish black. Very easily attacked. 
 
 (40 sec.) 
 Pyrolusite. Black fibrous surface. Soft. Brown solution. 
 
 B. Etched by HNO 3 , not by HC1. 
 (a) Without tarnish. 
 
 Enargite. Dull grayish black. Etches to fibrous structure. 
 Cu test. 
 
 Argentite. Smooth dull black. Ag test. Sectile. 
 
 Stephanite. Smooth dull black. Ag test. 
 (6) With a tarnish. 
 
 Chalcocite. Smooth black. Etched to a bluish tarnish, 
 later becoming peacock colors. 
 
 Bornite. Pitted. Purple color. Etches to a peacock tarnish. 
 
 Reacts for both Fe and Cu. 
 (c) With a deposit. 
 
 Galena. Smooth black. Etches easily, with a yellow de- 
 posit. 
 
 Bournonite. Smooth dull black. Etches easily, with yel- 
 lowish opalescent deposit. Cu test. 
 
 Stibnite. Smooth dull black. Etches fairly slowly to a 
 fibrous structure with a chalky deposit. 
 
 Tetrahedrite. Smooth. Bluish black. Etches with an opal- 
 escent deposit. Reacts for copper. 
 
 C. Unattacked by single acids. 
 Molybdenite. 
 
 Chromite. 
 
 Cassiterite. Black deposit by electric etching. 
 
 Columbite. 
 
 This paper, dealing with 37 species, is the most extensive so 
 far published on opaque mineral identification, and is intended 
 as a summary of results up to date. In etching, Bruce used con- 
 centrated acids for periods of several minutes, so that the reactions 
 are in many cases quite different from those produced by the 
 more dilute reagents and shorter time of etching advocated in 
 the present book. It is not clear, however, why oblique illumi- 
 nation alone has been employed for Bruce's determinations. 
 This has been found of considerable service in examining trans- 
 parent sulphides, like sphalerite or ruby silver, but this result 
 may easily be obtained by cutting off the vertical illumination 
 temporarily. Experience has indicated that vertical illumination 
 
OF THE OPAQUE MINERALS 13 
 
 is more effective in the case of opaque minerals, since the per- 
 fectly smooth surface of any opaque substance, regardless of its 
 real color, will appear black, or nearly so, with oblique light, 
 except with very low powers; and a rough surface, which alone 
 will show the true color of tha mineral by inclined illumination, 
 is extremely undesirable from* many standpoints. 
 
 - Rogers 44 stated that magnetite has a rough surface ; hematite 
 is rather smooth, faintly scratched; bornite and chalcopyrite are 
 easily recognized by their colors. He also said that with plane 
 polarized light, covellite shows pleochroism, deep blue (parallel 
 to the plane of vibration of the nicol) to light blue (perpendicular 
 to this). 
 
 -Kraus and Goldsberry 23 examined polished bornite crystals 
 to ascertain their purity, and analyzed material from the same 
 crystals, but gave no determinative criteria for identifying this 
 mineral. 
 
 1915. Chamot 15 published a valuable book on microchemistry, 
 giving microchemical tests for the elements, manipulation, etc., 
 and methods of polishing, intended especially for metals and 
 alloys, but applicable to a great extent to opaque minerals as 
 well. 
 
 Thompson 43 mentioned the following minerals but gave no 
 criteria for their identification: Pyrite, chalcocite, bornite, chal- 
 copyrite, covellite, enargite, sphalerite, tetrahedrite and a white 
 alteration product of enargite. Following earlier work by others, 
 he etched covellite and enargite with KCN and stated that it 
 developed a structure in them. 
 
 From this summary it is evident that a considerable number 
 of the commoner and some of the rarer opaque minerals have 
 been studied and described, and in addition undoubtedly much 
 valuable work of this nature has been done, but not yet pub- 
 lished. Nevertheless, no systematic attempt appears to have 
 been made to cover the whole field of the opaque minerals, and 
 little attention has been paid to standardization of methods, many 
 of which appear to have been developed without regard to previous 
 work. In consequence, much effort has been wasted in duplica- 
 tion, and variable results have often been obtained, while most of 
 the opaque minerals have been left without means of determination 
 by the microscopic method. 
 
14 MICROSCOPICAL DETERMINATION 
 
 SCOPE OF PRESENT WORK 
 
 In 1911, a mineralographic investigation of some of the sulphide 
 ores of copper was undertaken by L. C. Graton and the author. 17 
 It was at once seen to be very essential to know what the differ- 
 ent ore minerals looked like, and how they behaved chemically, 
 under the microscope. Accordingly, many previously deter- 
 mined specimens of the commoner opaque minerals were assembled 
 and studied, and thus it was possible to reduce materially the 
 uncertainties in determination, and often in interpretation of 
 structure. The author has continued the determinative part 
 of this work in the laboratory of Mining Geology of Harvard 
 University, and the present book is the result of investigations 
 carried on over a period of nearly four years. It does not discuss 
 the paragenesis or significance of the minerals and structures 
 involved. The great importance of these problems is evident, 
 but this book has been strictly confined to mineral identification. 
 It is devoted solely to determination of the physical and chemical 
 properties of the opaque minerals, as observed under the micro- 
 scope, with a classification of these data in such form as to permit 
 their ready application to problems of identification, somewhat 
 after the manner of Brush and Penfield's or Johannsen's deter- 
 minative tables. The primary object has been the production of a 
 practical and simple scheme of mineral identification, and accord- 
 ingly only those lines of investigation have been pursued which 
 contributed directly toward this end. Further work will probably 
 modify some of the results attained, especially when extended to 
 additional associations of minerals and to sub-species and varia- 
 tions not yet studied. The methods of investigation will also 
 doubtless be improved, b.ut the present results have been found 
 to afford a practical means of mineral determination and may 
 serve as a ground work for future research in a field that promises 
 to be of great importance. In a work dealing with so new a field, 
 however, errors and omissions are likely to be found, and notice of 
 any such will be much appreciated. 
 
 The collection studied includes 186 definite minerals, a few of 
 which are as yet unidentified, or perhaps new; a few mixtures, 
 with known and with unknown constituents, which have been 
 previously regarded as true minerals, and as such have been given 
 mineral names ; and some definite varieties of known species, such 
 as the argentiferous tetrahedrite, freibergite. The minerals have 
 
OF THE OPAQUE MINERALS 15 
 
 been assembled from the collections of various mineralogical mu- 
 seums, with some from private collections and mineral dealers. 
 The list comprises a few metallic elements and oxides, and prac- 
 tically all the minerals of the sulphide and sulpho-salt groups, in- 
 cluding selenides, tellurides and arsenides. A few, like cuprite or 
 the ruby silvers, are transparent, but are included because of their 
 character and associatiens. Tfiere are a number of named species 
 not represented, but only a few of these are true minerals, most of 
 them being admittedly mixtures, or very dubious. 
 
 In the case of each mineral, specimens from two or more local- 
 ities have been secured and studied, whenever possible, as a 
 check on the uniformity of the findings, and specimens previously 
 determined by chemical or crystallographic methods have been 
 given preference in every instance. Nevertheless, many species 
 are represented by but a single specimen, and in order that the 
 reader may judge of the reliability of the determination, the 
 number of localities from which specimens have been secured 
 and studied has been put in parentheses after each mineral 
 name in the Index of Minerals, (n) indicates more than five 
 localities. When only one specimen was available, or when the 
 mineral is dubious, a letter or symbol is added to indicate the 
 value of the description. Thus: G = Reliable. F = Probably 
 reliable. ? = Doubtful. For example, there is only one specimen 
 of glaucodot in the collection, but it is a large crystal, definitely 
 identified. This, of course, increases the value of the observa- 
 tions on this mineral, but does not assure that its properties would 
 be constant in different localities. It has been found, however, 
 that specimens of the same mineral from different localities 
 usually correspond very closely. For the commoner minerals, 
 especially, this fact has been established by observations on hun- 
 dreds of specimens of ore from various parts of the world. 
 
 The author wishes especially to express his indebtedness to 
 Professor L. C. Graton, of Harvard University, for much valuable 
 advice and helpful criticism throughout this work, and for sup- 
 plying much material of great value to the study. Professor 
 J. E. Wolff and Professor Charles Palache, of Harvard University, 
 have very kindly furnished much material from the Museum 
 Collections, and have given information that has been of great 
 assistance. Professor Waldemar Lindgren, of the Massachu- 
 setts Institute of Technology, has been kind enough to give this 
 
16 MICROSCOPICAL DETERMINATION 
 
 work, in manuscript form, a practical trial and to offer valuable 
 suggestions. To the generosity of Mr. W. A. Roebling of Trenton, 
 N. J., is due the opportunity to study many very rare and valuable 
 specimens of his collection, thereby adding greatly to the complete- 
 ness of the work. Much valuable material has been obtained 
 through the courtesy and generosity of Drs. G. P. Merrill and 
 J. E. Pogue of the National Museum at Washington; Professor 
 W. E. Ford of Yale University; and Dr. L. P. Gratacap of the 
 American Museum of Natural History, N. Y., to whom grateful 
 acknowledgment is made. The spirit which has led numerous 
 practicing geologists and engineers to transmit interesting and 
 unusual materials from many parts of the world is also much 
 appreciated. 
 
 BIBLIOGRAPHY 
 
 The following list includes the titles of all papers known to 
 the author, in which use has been made of mineralography whether 
 dealing directly with mineral identification or not, or which have 
 been referred to in preparing this work; it may be regarded as 
 fairly complete. The papers are referred to by number in the 
 text. 
 
 1. ALLEN, E. T. Private communication. 
 
 2. BASTIN, E. S. Metasomatism in downward sulphide enrichment. Econ. 
 
 Geology, Vol. VIII, 1912, p. 51. 
 
 3. - - Geology of the pitchblende ores of Colorado. U. S. Geol. Survey, 
 
 Prof. Paper 90-A, 1914. 
 
 4. BAUMHAUER, H. Ueber die mikroskopische Beschaffenheit eines Bunt- 
 
 kupfererzes von Chloride (New Mexico). Zeitschr. fiirKryst., etc., Vol. 
 10, 1885, p. 447. 
 
 5. BEIJERINCK, F. Ueber das Leitungsvermogen der Mineralien fiir Elektri- 
 
 citat Jahrb. fiir Min., etc., Beilage Band 11, 1897-8, pp. 403-474. 
 
 6. BERZELIUS, J. J. [note] Gilb. Ann., Vol. XLVIII, 1814, p. 209. 
 
 7. BEYSCHLAG, VOGT and KRUSCH. Ore deposits, Vol. I. Translated by S. J. 
 
 Truscott, London, 1914 (original, 1909). 
 
 8. BOYLE, A. C., JR. Geology and ore deposits of the Bully Hill mining dis- 
 
 trict, California. Am. Inst. Min. Eng., Trans., Vol. XLVIII, 1914, pp. 
 67-114. 
 
 9. BRUCE, E. L. Microscopic tests on opaque minerals. School of Mines 
 
 Quarterly, Vol. 35, 1914, p. 187. 
 
 10. BRUNTON, S. Some notes on titaniferous magnetite. Econ. Geology, 
 
 Vol. VII, 1912, p. 670. 
 
 11. BUTLER, B. S. Geology and ore deposits of the San Francisco region, 
 
 Utah. U. S. Geol. Survey, Prof. Paper 80, 1913. 
 
OF THE OPAQUE MINERALS 17 
 
 12. CAMPBELL, W. The microscopic examination of opaque minerals. Econ. 
 
 Geology, Vol. I, 1906, p. 751. 
 
 13. and KNIGHT, C. W. A microscopic examination of the cobalt nickel 
 
 arsenides and silver deposits of Temiskaming. Econ. Geology, Vol. I, 
 1906, p. 767. 
 
 14. The microstructure ol nickeliferous pyrrhotite. Econ. Geology, 
 
 Vol. II, 1907, p. 350. 
 
 15. CHAMOT, E. M. Elementary chefcnical microscopy. New York, 1915. 
 
 16. FINLAYSON, A. M. The pyritic deposits of Huelva, Spain. Econ. Geol- 
 
 ogy, Vol. V, 1910, pp. 357 and 403. 
 
 17. GRATON, L. C. and MURDOCH, J. The sulphide ores of copper; some re- 
 
 sults of microscopic study. Am. Inst. Min. Eng., Trans., May, 1913, 
 p. 741. 
 
 18. HARRINGTON, B. J. On the formula of bornite. Am. Jour. Sci., 4th series, 
 
 Vol. 16, 1903, p. 151. 
 
 19. HUSSAK, E. Ueber die Mikrostruktur einiger Brasilianischer Titanmag- 
 
 neteisensteine. Neues Jahrb. fur Min., etc., Vol. I, 1904, p. 94. 
 
 20. JOHANNSEN, A. Manual of petrographic methods. New York, 1914, p. 572. 
 
 21. JULIEN, A. A. On the variation of decomposition of the iron pyrites, its 
 
 cause and relation to density. Ann. N. Y. Acad. Sci., Vol. IV, 1885, 
 p. 141. 
 
 22. KOENIGSBERGER, J. Ueber einen Apparat zur Erkennung und Messung 
 
 optischer Anisotropie undurchsichtiger Substanzen und dessen Verwen- 
 dung. Centralblatt fur Min., etc., 1908, pp. 565, 597. 
 
 23. KRAUS, E. H. and GOLDSBERRY, J. P. The chemical composition of born- 
 
 ite and its relation to other sulpho-salts. Am. Jour. Sci., 4th series, Vol. 
 37, 1914, p. 539. 
 
 24. LANEY, F. B. The relation of bornite and chalcocite in the copper ores of 
 
 the Virgilina district of North Carolina and Virginia. Econ. Geology, 
 Vol. VI, 1911, p. 399. 
 
 25. LEE, M. L. A geologic study of the Elisa mine, Sonora, Mexico. Econ. 
 
 Geology, Vol. VII, 1912, p. 324. 
 
 26. LEO, M. Die Anlauffarben. Dresden, 1911. 
 
 27. LINCOLN, F. C. Certain natural associations of gold. Econ. Geology, 
 
 Vol. VI, 1911, p. 247. 
 
 28. LINDGREN, W. Mineral deposits. New York, 1913. 
 
 29. and WHITEHEAD, W. L. A deposit of jamesonite near Zimapan, 
 
 Mexico. Econ. Geology, Vol. IX, 1914, p. 435. 
 
 30. RANSOME, F. L. Copper deposits near Superior, Arizona. U. S. Geol. 
 
 Survey., Bull. 540, Part I, 1914, p. 139. 
 
 31. RAY, J. C. The reflecting microscope in mining geology and metallurgy. 
 
 Min. & Sci. Press, June, 1914, p. 922. 
 
 32. - - Paragenesis of the ore minerals in the Butte district, Montana. Econ. 
 
 Geology, Vol. IX, 1914, p. 463. 
 
 33. RIDGWAY, R. Color standards and nomenclature. Olney, 111., 1912. 
 
 34. ROGERS, A. F. Upward secondary sulphide enrichment and chalcocite 
 
 formation at Butte, Montana. Econ. Geology, Vol. VIII, 1913, p. 781. 
 
18 MICROSCOPICAL DETERMINATION 
 
 35. Secondary sulphide enrichment of copper ores with special reference 
 
 to microscopic study. Min. & Sci. Press, October, 1914, p. 681. 
 
 36.. - The chemical composition of bornite. Science, new series, Vol. 
 XLII, 1915, p. 386. 
 
 37. SIMPSON, J. F. The relation of copper to pyrite in the lean copper ores of 
 
 Butte, Montana. Econ. Geology, Vol. Ill, 1908, p. 628. 
 
 38. SINGEWALD, J. T. Microstructure of titaniferous magnetite. Econ. Geol- 
 
 ogy, Vol. VIII, 1913, p. 207. 
 
 39. - The titaniferous magnetites of the United States, U. S. Bureau of 
 
 Mines, Bull. 64, 1913. 
 
 40. SORBY, H. C. On the microscopic structure of the calcareous grits of the 
 
 Yorkshire coast. Quart. Jour. Geol. Soc., Vol. VII, 1851, pp. 1-6. 
 
 41. - Preparation of transparent sections of rocks and minerals. Northern 
 
 Microscopist, Vol. II, 1828, pp. 101-106, 133-140. 
 
 42. THOMPSON, A. P. The relation of pyrrhotite to chalcopyrite and other 
 
 sulphides. Econ. Geology, Vol. IX, 1914, p. 153. 
 
 43. - The occurrence of covellite at Butte, Montana. Am. Inst. Min. Eng., 
 
 Bull. 100, April, 1915, p. 645. 
 
 44. TURNER, H. W. and ROGERS, A. F. A geologic and microscopic study of a 
 
 magmatic copper sulphide deposit in Plumas County, California, and its 
 modification by ascending secondary enrichment. Econ. Geology, Vol. 
 IX, 1914, p. 359. 
 
 45. WARREN, C. H. Petrography and mineralogy of Iron Mine Hill, Cumber- 
 
 land, R. I. Am. Jour. Sci., 4th series, Vol. 25, 1908, p. 15. 
 
 46. WINCHELL, N. H. and WINCHELL, A. N. Elements of optical mineralogy. 
 
 2d Appendix. New York, 1909. 
 
 47. BERG, G. Mikroskopische Untersuchung der Erzlagerstatten. Berlin, 1915. 
 
 (This came to hand too late for more than a brief note. Berg has classified 
 a number of the commoner ore minerals by their appearance in reflected 
 light (in thin sections) and by their different microchemical behavior. 
 He apparently has not used polished sections.) 
 
TECHNIQUE OF MINERALOGRAPHY 
 
 P ( OLISfflNG 
 
 The mineral to be examined %hould be polished so that it has 
 rather large areas shiny, or very smooth, and free from pits, and 
 should have few or no scratches. This relatively perfect polish 
 is necessary in this work, as a much pitted or scratched surface 
 often obscures the true color of a mineral, and may even modify 
 somewhat the microchemical reactions. For example, some of 
 the hard minerals, like hematite or magnetite, appear gray instead 
 of white, if the surface has not at least fair-sized areas free from 
 pits. Minerals, like pyrite, which scratch instead of pitting, 
 should not be polished too shiny after they have reached a con- 
 dition permitting identification, as this would develop too much 
 relief as compared with adjacent softer minerals a thing which 
 is not desirable. 
 
 Campbell 12 and Ray 31 give accounts of polishing methods for 
 which the reader is referred to their respective papers. Other 
 workers have variations of their own, and individual preferences will 
 differ. The following method has been found most satisfactory 
 in the opinion of the author. 
 
 FIG. 1. Polishing Apparatus. 
 
 The grinding apparatus used is Sauveur's machine for polishing 
 steel. (See Fig. 1.) It consists of a horizontal spindle with two 
 vertical iron discs 8 inches diameter and f inch thick, run at about 
 
 19 
 
20 MICROSCOPICAL DETERMINATION 
 
 1200 revolutions per minute. This gives four polishing surfaces. 
 The first is a J-inch carborundum wheel laid against one side of 
 the first iron disc. The carborundum wheel that gives best 
 results is a mixture of 40-, 60- and 80-mesh carborundum, soft- 
 bonded, so it will not readily clog or grow dull.* On the other 
 side of the first disc is stretched a heavy canvas cover, armed with 
 220-mesh carborundum powder, mixed with water to a thin pasty 
 consistency, and applied to the revolving wheel with a flat brush 
 about 1| inches wide. The other disc is covered on both sides 
 with broadcloth, to which is similarly applied a very thin paste of 
 tripoli powder, on one side, and of rouge on the other. The rouge 
 and tripoli used in polishing steel are quite satisfactory for minerals, 
 and if carborundum powder is not available, flour emery instead 
 may be used on the canvas wheel. 
 
 Specimens varying in size from over two inches in diameter 
 down to the smallest piece that can be held in the fingers may be 
 handled on these wheels. Preferably, the rough chips are about 
 half an inch to an inch square and half an inch thick, and with 
 one fairly even side or face to begin with, as by polishing on this 
 face, time is saved in the grinding. The surface may be most rapidly 
 flattened by pressing it diagonally against the corner of the carbo- 
 rundum wheel, before applying it to the smooth side of the wheel. 
 
 The carborundum wheel is generally used dry, but may be fed 
 with water if the specimen to be ground is brittle, or likely to be 
 injured by heating. In either case, it is often advisable to cool 
 the specimen from time to time by a moment's immersion in 
 water. On delicate specimens, a diamond saw may be used 
 instead of this wheel, but for general work, the carborundum 
 wheel is more satisfactory and much cheaper. The purpose of 
 the carborundum wheel is to cut a flat surface preparatory to the 
 real polishing. It is also used to bevel off the edge of the ground 
 face all the way around, which must be done to avoid the danger 
 of tearing the cloth of the other wheels by sharp or irregular pro- 
 jections. When this has been done, the specimen and the hands 
 are carefully rinsed, to remove any particles of carborundum or 
 loose fragments of the specimen, and this procedure is repeated 
 after the operation on each wheel has been completed and before 
 passing to the next wheel. 
 
 * The Carborundum Company's specifications are as follows: Grit 403; Grade M; 
 Bond B3. 
 
HITE/ COLOR 
 
 OF THE OPAQUE MINERALS 21 
 
 Then the specimen is applied to the canvas . wheel, which is 
 kept wet and well supplied with carborundum powder. Here the 
 pits produced by the coarse wheel are ground out, and the harder 
 minerals, like magnetite or pyrite, are given practically whatever 
 polish they are to receive. I^it'tle or no relief is developed here, 
 and the wheel is very valuable Jor producing a plane surface free 
 from pits. Most specimens should be kept here longest, so as to 
 save time and trouble later on. Very soft or brittle specimens, 
 like massive chalcocite, should be started on this wheel, to avoid 
 " burning " or cracking by heat on the carborundum wheel. Con- 
 siderable pressure may be applied here, but it is desirable that this 
 be lessened at the end of grinding, to make the scratches less deep. 
 
 When the surface is plane and unpitted, and the specimen 
 and hands have been rinsed, polishing on the third, or tripoli, 
 wheel is begun. The specimen should not be pressed heavily, 
 but only moderately, against this wheel. Here the softer min- 
 erals, such as chalcopyrite, are polished, though usually with 
 fine scratches still visible. This wheel also develops relief, by 
 attacking the softer without much affecting the harder constitu- 
 ents. Too great relief is not desirable, as the hard constituents 
 would then stand high and prevent the formation of a flat surface 
 on the softer ones, which, though shiny, would then appear grooved 
 and uneven, and their relationships would be obscured. More- 
 over, these hard minerals, if projecting prominently, tear the 
 surface of the cloth, and wear it out very rapidly. All these 
 difficulties are avoided by removing most of the pits on the canvas 
 wheel, and not polishing too long or too hard on the tripoli wheel. 
 
 When the softer minerals appear smooth, the specimen is again 
 rinsed, and transferred to the last, or rouge, wheel. This usually 
 does little more than give a burnish to the specimen, but in the 
 case of chalcocite, or a similarly soft mineral, considerable polish- 
 ing is done here, and the scratches from the tripoli wheel are 
 removed. This final burnish is very important, but it is not usually 
 necessary to polish on this wheel more than five or ten seconds. 
 The specimen is then dried by wiping thoroughly with a soft 
 cloth, or by rinsing in alcohol and drying in an air blast, as any 
 moisture will injure the surface of the rouge block, to which the 
 specimen is next transferred for the last step in its preparation. 
 The rouge block consists of a piece of chamois skin stretched 
 over a flat block of wood and fed with a little dry rouge. On this 
 
22 MICROSCOPICAL DETERMINATION 
 
 the specimen is rubbed briskly, but without excessive pressure, 
 for a few seconds, to give it a final burnish, and to remove any 
 films or specks of dirt that may have adhered to the surface. The 
 rouge block must be kept free from all grit and dirt, as this would 
 scratch and mar the surface of the specimen. It should be kept 
 covered, except when in actual use, and all mineral or dirt frag- 
 ments removed by brushing. 
 
 After a moderate amount of practice, in which experience is 
 gained as to the appropriate pressure to apply, and the minimum 
 of time required to produce the desired effect, an average specimen 
 may be polished in six or seven minutes. 
 
 Specimens too small to be held in the fingers may be polished 
 by first mounting them in partly melted sealing wax, and a flat 
 surface produced before the wax hardens by pressing the wax 
 containing the chip, face down on a wet glass plate, or by laying 
 the piece face down on a wet glass and running melted wax over 
 it. Then the wax and specimen together may easily be polished. 
 Of course it is not to be put on the dry carborundum wheel, as 
 the heat of friction would melt the wax, but is to be started on the 
 canvas. 
 
 For polishing powders, or small grains of minerals, the following 
 procedure is convenient. A flat surface of sealing wax is softened, 
 and the powder sprinkled thickly over this. It may be pressed 
 in by the finger while the wax is still soft, or melted in by 
 additional heat. Then the softened surface is pressed on a wet 
 glass plate, so as to produce a flat surface, which is polished 
 in the ordinary way, except that in the case of fine powders, 
 the tripoli wheel is the coarsest one used. By this means, al- 
 most impalpable powders may be polished and studied, and it 
 is especially valuable for the examination of churn drill pulps, 
 mill tailings or concentrates, powders and minute fragments of 
 synthetic minerals, or tiny crystals of rare minerals. In the case 
 of crystals, polishing may be done in carefully oriented direc- 
 tions, and a number of oriented surfaces may be polished on 
 a single piece. Crystal-lined vugs, or crusts of crystals, may be 
 filled with melted wax and polished down carefully without 
 destroying either the crystals or their arrangement or injuring the 
 polishing wheels. Fusible alloys, or dental enamel, may be used 
 instead of wax, especially for mineral grains that are hard and 
 apt to tear out when polished. 
 
H 
 
 OLOR 
 
 OF THE OPAQUE MINERALS 
 
 23 
 
 The method of polishing outlined above, or a similar one, is 
 very desirable as a time- and labor-saving arrangement, but is not 
 absolutely essential. As a matter of fact, even at a remote mine 
 or prospect, satisfactory polished sections may be secured without 
 an excessive expenditure of ti^tie, with nothing more elaborate 
 than a file or two, a number of sheets of emery paper of varying 
 degrees of fineness, a strip of chamois skin and a little rouge. 
 If a grindstone is available, of course much time can be saved in 
 preparing a flat surface on the ore chips. 
 
 Glass plate 
 
 Specimen / 
 
 Mounting wax 
 
 SIDE VIEW 
 
 TOP VIEW 
 
 FIG. 2. Method of Mounting. 
 MOUNTING 
 
 Specimens may be mounted for examination on the stage of the 
 microscope in any one of a number of ways by which the polished 
 surface is held perpendicular to the axis of the microscope. It 
 has been found convenient to mount the specimen, by means of a 
 lump of modeling wax, on a metal plate 3 inches long, 1 inch wide 
 and J inch thick. The polished surface is made parallel to the 
 bottom of the mount by pressing it down with a piece of plate 
 glass until this rests on the top of a metal ring of uniform height, 
 conveniently about f inch, which is placed temporarily on the 
 steel plate and around the specimen. (See Fig. 2.) This is a 
 modification of Campbell's cup method. The mounted specimen 
 may then be placed on the microscope stage without need of 
 further adjustment. To permit chemical and physical tests on 
 the polished surface directly under the microscope, a type of in- 
 strument that holds the specimen with the polished surface upward 
 should be used, but for other purposes, instruments employing in- 
 verted mounting are as satisfactory. 
 
24 
 
 MICROSCOPICAL DETERMINATION 
 
 EXAMINATION 
 
 For the microscopic examination of polished surfaces of opaque 
 minerals, an ordinary metallographic microscope is used. This 
 carries a special reflector, called a " vertical illuminator/' screwed 
 into the microscope tube like an objective, by means of which 
 light is directed vertically downward on the polished surface, and 
 reflected back from this up through the instrument to the eye. 
 Any ordinary microscope, t>h&t permits sufficient elevation of 
 the tube to admit the vertical illuminator and the mounted 
 specimen, may be used for this work. If the petrographic micro- 
 
 FIG. 3. Prism 
 Illuminator. 
 
 FIG. 4. Plane Glass 
 Illuminator. 
 
 FIG. 5. Short-mounted 
 Objective. 
 
 scope is used, the analyzer ordinarily should be thrown out. For use 
 with daylight, the vertical illuminator is a totally reflecting prism 
 (Fig. 3) ; with artificial light, more even illumination is secured 
 by the use of a reflector consisting of a plane glass disc (Fig. 4). 
 
 If daylight is used, care must be taken also to avoid reflec- 
 tions from buildings, trees, or clouds, as these affect the colors 
 of minerals. For the most accurate results, an open, cloudless 
 sky is necessary; moreover it must not be too late in the afternoon, 
 as the quality of light changes rapidly then, and becomes somewhat 
 polarized. In using objectives of higher power than about 16 mm. 
 by daylight, the short-mounted form (Fig. 5) should be used, as 
 with the ordinary mounting only a narrow strip across the field is 
 properly illuminated by the prism. 
 
 The most satisfactory artificial light has been found to be that 
 of an electric arc, reduced in intensity by passing through a ground 
 glass screen. This gives practically the same color values as 
 daylight. The colors of minerals have been standardized by 
 this light or daylight. 
 
 Methods of comparing colors under the microscope will be 
 found on page 26. All bright oblique light should be shut off 
 from the specimen by a screen which allows light from the side 
 to fall only on the aperture of the vertical illuminator. This 
 
WHITE/ 
 
 OF THE OPAQUE MINERALS 25 
 
 will eliminate the confusion arising from the mingled effects of 
 vertical and oblique light. For observing transparent minerals, 
 the screen is removed, and the aperture of the vertical illuminator 
 closed, so that oblique light alone falls on the surface, and by this 
 means their color by transmitted light may be observed, even in 
 very small grains. 
 
 MAGNIFICATION 
 
 The most convenient magnification for ordinary purposes is 
 about 50 diameters, but frequently 200 may be employed to ad- 
 vantage. For very detailed examination, by artificial light, this 
 may be increased to 800 or more (with an oil immersion objective). 
 In daylight, 400 diameters is about the upper working limit, 
 as above this the image is usually too faint and blurred to be 
 observed accurately. In some cases a low power objective, or 
 even a hand lens, may be used advantageously to observe the 
 larger relationships of minerals. 
 
 PHOTOGRAPHING 
 
 Microphotographs of polished specimens can be made with 
 little difficulty. They are very useful for purposes of record and 
 comparison, and in written reports give a clearer idea of the 
 material than could possibly be conveyed by a lengthy description. 
 Microphotography may be accomplished by attaching a camera 
 box to the end of the microscope, which itself serves as the camera 
 lens. Artificial light is usually employed and the ground glass 
 screen omitted, to permit of shorter exposures. In general, the 
 equipment and procedure are the same as in metallography. 
 The colors of the common minerals occurring in ores, however, 
 such as chalcopyrite, bornite, covellite, etc., require the use of 
 color screens to develop contrast between two or more minerals 
 which in white light may have almost the same photographic 
 intensity. For instance, with an ordinary contrast plate and 
 no color screen, in the combinations bornite and chalcocite, 
 covellite and chalcocite, and chalcopyrite and galena, the compo- 
 nent minerals have practically the same color values, and often 
 the contact between them is hardly visible. But with a mono- 
 chromatic screen which will make one of each pair appear dark, 
 beautiful results may be obtained. 
 
 For color screens, Wratten and Wainwright light filters have 
 been used with great success in this sort of microphotography, and 
 
26 MICROSCOPICAL DETERMINATION 
 
 the following grades have been employed: K2 = yellow; A = red; 
 B = green; C = blue. The red of course can be used success- 
 fully only with panchromatic plates. The others can be used with 
 Cramer Contrast or Seed L ortho, non-halation plates. 
 
 The following data will serve as a guide in photographing these 
 or similar combinations of minerals. 
 
 WHITE LIGHT. Cramer Contrast plate sphalerite and galena ; 
 etched chalcocite; pyrite, galena, or chalcopyrite, in gangue. 
 
 YELLOW SCREEN. Cramer Contrast plate bornite and chal- 
 cocite; bornite and chalcopyrite; covellite and chalcocite; covellite 
 and chalcopyrite; pyrite and chalcopyrite; " mottled chalcocite." 
 
 GREEN SCREEN. Cramer Contrast or Seed L Ortho (n.h.) plate 
 - same as with yellow screen, but Cramer Contrast requires 
 very long exposure, and Seed plate does not give so bright a 
 negative. The yellow screen is better in most cases. 
 
 BLUE SCREEN. Cramer Contrast or Seed L Ortho plate - 
 chalcopyrite and chalcocite; tennantite and enargite. 
 
 RED SCREEN. Panchromatic plate covellite and bornite. 
 
 The preceding paragraphs apply best to pairs of minerals, but 
 when three or more are to be photographed the best combination 
 to use is Seed's L Ortho, or a panchromatic plate * with the K2, 
 or yellow screen. This will give nearly the true color values to a 
 complex combination of minerals, such as sphalerite, galena, chal- 
 copyrite, tennantite or tetrahedrite, bornite, and gangue, a not 
 unusual assemblage in certain types of sulphide ore. 
 
 The table of exposures given on the following page is not com- 
 plete, but covers the parts likely to be of use in ore photography, 
 both as regards magnifications and combinations of minerals. 
 
 COLOR COMPARISON 
 
 The accurate determination of the colors of minerals is one 
 of the most important steps in their identification, and for this 
 reason demands careful attention. It is also one of the most 
 difficult things to accomplish, and for the most precise distinctions 
 requires a certain amount of practice. The importance of color 
 is due to the fact that in reflected light more than three-quarters 
 of the sulphide minerals are white, or nearly white, and in con- 
 
 * Very recently the Eastman Kodak Co. has put on the market the Wratten M Plate, 
 especially designed for microscopic photography. It is highly efficient, and their accom- 
 panying booklet, " Photomicrography," is also highly to be recommended to workers in 
 this line. 
 
HI 
 
 OLOR 
 
 OF THE OPAQUE MINERALS 
 
 EXPOSURES 
 
 27 
 
 Screen 
 
 None 
 
 Green "B" 
 
 Yellow "K2" 
 
 Blue " C " 
 
 Red 
 "A" 
 
 Plate 
 
 C.C. 
 
 SLO 
 
 C.C. 
 
 w+w 
 
 SLO 
 
 C.C. 
 
 W+W 
 
 SLO 
 
 C.C. 
 
 W+W' 
 
 W+W 
 
 Magnification: 
 45 
 55 
 65 
 85 
 130 
 170 
 250 
 300 
 375 
 750 
 840 
 1670 
 
 1 
 
 2 
 
 "l'* 
 
 '."Si' 
 
 60' 
 1*15 
 
 > 
 
 
 2 
 2^ 
 3 
 4 
 5 
 7 
 
 10 ' 
 15 
 
 "Y 
 
 .... 
 
 'ii' 
 
 "2 
 
 2 
 
 '2 
 
 
 
 "4" 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 6 
 
 2* 
 
 
 5- 
 5+ 
 10 
 
 
 
 
 
 
 
 
 
 3* 
 
 12+ 
 20 
 
 
 
 
 
 | 
 
 10 
 12 
 15 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Key: SLO = Seed L Ortho, non-halation plate. 
 
 C. C. = Cramer Contrast plate. 
 
 W + W = Wratten and Wainwright Panchromatic plate. 
 * = minutes. Ordinary figures indicate seconds. 
 
 Note. These exposures are figured for the B. & L. Model D Balopticon, but the 
 same proportions will hold for light of different intensity. 
 
 sequence comparatively delicate distinctions must be made to 
 separate this large class into smaller groups which may be more 
 readily sub-divided by microchemical tests. Fortunately many 
 of these minerals possess various tints, such as creamy, or bluish, 
 or grayish white, and may conveniently be separated into groups, by 
 comparison with a standard. The primary standard is pure galena, 
 and the position in the color scale of every white mineral is estab- 
 lished by its appearance when compared with galena. There are 
 also subordinate standards for the different qualities of white, such 
 as silver (pure, not coin silver) for the creamy white minerals, 
 tetrahedrite for the grayish white, and cuprite for the bluish white. 
 For distinctly gray minerals, dark colored sphalerite may be used, 
 if necessary. 
 
 The comparison may be made in several ways. The essential 
 principle is to get the two objects to be compared as close together 
 as possible in the field of vision. The following method has been 
 used in this work and found to be very satisfactory. Each of the 
 color standards is so ground that one side of the polished surface 
 is bounded by a straight line;- the specimen to be compared is 
 similarly prepared and is mounted, together with the standard, 
 so that the straight edges of the two are in contact and the two 
 
28 
 
 MICROSCOPICAL DETERMINATION 
 
 polished surfaces are in the same plane, and can be directly com- 
 pared under the microscope. (See Fig. 6.) Exceedingly delicate 
 comparisons of color may be made in this way, and usually it is 
 easy to prepare the specimen, though in the case of small grains in- 
 cluded in other minerals the specimen has to be cut down care- 
 
 standard 
 
 Metal plate 
 New mineral Standard mineral / 
 
 Mounting 
 
 Metal plate 
 
 SIDE VIEW 
 
 Mounting: 
 
 TOP VIEW 
 
 FIG. 6. Method of Comparing Colors. 
 
 fully until an area of the mineral in question is at the straight edge. 
 Another method employs a comparison eyepiece, which projects 
 the images from two separate objects into one eyepiece, so that one- 
 half the field is occupied by the image of one object and the other 
 half by that of the other. This has the advantage that a small 
 area in the middle of a specimen may be easily and quickly com- 
 pared with the standard. 
 
 The beginner in this work may at the very outset experience 
 some difficulty in this matter of color determination, but it has been 
 found that the ability to distinguish minute differences in color 
 grows very rapidly with experience, and it is astonishing how much 
 more can be seen after a week's work than at the start. 
 
 As stated above, these determinations are comparative, with 
 an arbitrary standard, because the eye is not accurate enough to 
 carry such slight differences. Moreover, except in the case of 
 the distinctly colored minerals, the differences are so slight that 
 even spectroscopic measurements of the reflected wave length 
 would probably be ineffective. The books on colors and color 
 standards deal with far brighter colors than most of the tinted 
 white minerals show. Ridgway's book on " Color Standards and 
 Nomenclature/' 34 giving 1100 named colors, is the best and latest 
 of its sort. He gives colored plates reproducing the shades and 
 tints of the spectrum colors, with a white blank for comparison 
 with the lightest tint of each color. Unfortunately, except for 
 the distinctly colored and gray minerals, which are relatively 
 few in number, all the sulphide minerals have colors falling some- 
 where between pure white and his lightest tint, usually much 
 
/ COLOR 
 
 OF THE OPAQUE MINERALS 29 
 
 nearer the white end, so his standards are of little use in this 
 connection. 
 
 HARDNESS DETERMINATION 
 
 Hardness is often indicated by the character of the polish which 
 a mineral will take. Very tiafd minerals may be either shiny 
 and very much pitted, like magnetite, or dull and scratched, like 
 pyrite. Medium minerals are smooth, or somewhat pitted, ac- 
 cording to their brittleness. These can usually be smoothed off 
 rather easily. Enargite is often considerably pitted, especially 
 with insufficient polishing. Soft minerals practically always 
 have a smooth, unpitted surface, but they are usually very easily 
 scratched. An exception is galena, which usually shows triangular 
 pits, not removed by later polishing, where fragments have been 
 torn out along the cubic cleavage by the coarse grinding. Or- 
 dinarily even minerals with perfect cleavage give no indication 
 of this on the polished surface. 
 
 c 
 
 edle^- 
 
 Handle j Needle 
 
 FIG. 7. Needle Mounted for Testing Hardness. 
 
 For determining the hardness of opaque minerals on the pol- 
 ished surface, it is convenient to use a fine needle (No. 10 Sharp), 
 mounted at an angle of about 30 to a J-ounce handle, 5 inches 
 long. (See Fig. 7.) The idea is to have weight enough in the 
 handle, when held near the middle, to cause the needle point to 
 scratch soft minerals without additional pressure of the hand. This 
 may be handled directly under the microscope, so that very small 
 areas may be tested easily. 
 
 Careful investigation with specially designed apparatus per- 
 mitting accurate determination of the hardness of minerals on the 
 polished section indicates that many minerals possess distinctly dif- 
 ferent hardness in different crystal directions, so that two random 
 sections of the same mineral in a polished section might give discord- 
 ant results on accurate measurement, and lead to the erroneous 
 supposition that two different minerals were present. On this ac- 
 count, it has not been considered advisable in this work to carry this 
 determination of hardness too far, lest confusion arise from the over- 
 lapping of hardness ranges of various minerals. Accordingly, only 
 three degrees of hardness are recognized: high, medium and low. 
 
30 MICROSCOPICAL DETERMINATION 
 
 With oblique light, harder minerals in contact with softer ones 
 show a bright rim on the side of the harder mineral towards the 
 direction of illumination (reversed, of course, in the field of view 
 of the microscope). With the prism illuminator this effect is most 
 delicately observed when the area under observation is close to the 
 edge of the field of view nearest the observer. This is the best 
 method of determining the relative hardness of minerals. 
 
 MICROCHEMICAL TESTS 
 
 Microchemical tests are the most important of the means of 
 classification, and in most cases are absolutely necessary, owing to 
 the fact that very many minerals have practically the same phys- 
 ical characteristics. 
 
 (PI 
 
 FIG. 8. Pipette. 
 
 Method of Application. The desired chemical reagent is best 
 applied by means of a capillary pipette, so that a very small drop 
 may be placed on the polished surface. This drop should be be- 
 tween 0.25 mm. and 2 or 3 mm., though in some cases it is allow- 
 able to use a larger drop, if the area of the mineral to be tested is 
 considerable. The pipette may be made of small soft glass tubing 
 drawn out to a fine point, so that the opening is about 0.25 mm. 
 in diameter. It is convenient to have the tip of the pipette bev- 
 elled, to facilitate the flow of reagent when the instrument is 
 touched in an inclined position to the specimen. (See Fig. 8.) The 
 surface to be tested must be made absolutely clean by first rubbing 
 on the rouge block, as any dirt or grease may not only render diffi- 
 cult the deposition of a drop of the reagent on the surface, but also 
 may retard or prevent reaction which would otherwise take place, 
 and so nullify the test. A separate pipette should be provided 
 for each reagent and labelled appropriately. After using, the 
 pipette should invariably be freed of excess reagent, either by 
 washing or otherwise; failure to observe this precaution may lead 
 to annoyance and even to erroneous results. 
 
 The application of the reagent may generally be best performed 
 directly in the field of view of the microscope, so that any point 
 may be selected and treated, thus permitting the testing of very 
 small grains of a mineral surrounded by other opaque minerals or 
 by gangue. (See Fig. 9.) This is important, as hybrid reactions 
 are often obtained by etching mixtures of minerals, leading to 
 
HI 
 
 OLOR 
 
 OF THE OPAQUE MINERALS 
 
 31 
 
 confusion in identification. This method of application of the 
 reagent has the advantage that the very beginning of a reaction 
 may be observed, and. the result followed through to the end. 
 This is very essential for some reactions, which start almost in- 
 stantly, and would be too far advanced to 
 observe if the specimen had* to be taken 
 from under the microscope, fne reagent 
 applied, and the specimen replaced for in- 
 spection of the effect. Moreover, instead of 
 spoiling the whole specimen, only so much 
 of the surface is etched as is desired, so 
 that comparison, may be made immediately 
 of etched and unetched areas of a mineral. 
 Reactions. After the reagent is applied, 
 a reaction is watched for. If there is no 
 indication that any change is beginning, 
 either in the mineral or reagent (except pos- 
 sibly that the latter evaporates rapidly), in 
 about twenty seconds, the reaction is pro- 
 nounced negative. If there is a reaction, 
 its rate, and the changes both in reagent 
 (coloration, evolution of gas, etc.) and 
 mineral, must be carefully noted. Then FlG - 9. Method of Using Pi- 
 
 ..! . . .1 . .1 pette (hardness may be tested 
 
 without unmounting the specimen, the re- f n the v same way / usmg t ,he 
 agent is gently rinsed off with water or al- mounted needle. See Fig. 7). 
 cohol, and before rubbing, which would destroy any coating that 
 had been formed, the specimen is examined again to observe the 
 nature of the change, whether tarnish, or coating (black by vertical, 
 and white or colored by oblique, light), or solution of the surface, 
 shown by a roughening, with or without blackening. Sometimes 
 etch-figures are developed. Some minerals are tarnished by acid 
 fumes, while the acid itself leaves them apparently unchanged; 
 this results in a halo of alteration surrounding the drop of reagent, 
 but no evident attack on the area actually covered by the drop. 
 
 Then the specimen is dried off, rubbed on the rouge block and 
 again examined, to determine whether the tarnish or coloration 
 of the mineral is persistent, or whether it rubs off, leaving a clean 
 surface with practically the original color of the mineral. 
 
 The different types and speeds of reaction are often very im- 
 portant in distinguishing minerals, several of which might be at- 
 
32 MICROSCOPICAL DETERMINATION 
 
 tacked by the same reagent, but in different ways. It is therefore 
 necessary to note carefully each feature of the reaction. 
 
 Some reactions are affected by the presence of other minerals. In 
 testing very small areas, the drop of reagent necessarily overlaps 
 onto the surrounding minerals, some of which may be affected. 
 Calcite is particularly apt to obscure reactions with acid by neu- 
 tralizing the reagent so quickly that it does not have time to make 
 appreciable attack on the mineral for which it was intended. This 
 possibility of interference of other minerals is the one perhaps most 
 likely to cause erroneous results, but with the exercise of care in 
 suspicious cases, difficulties may usually be avoided. In case of 
 doubt, it is best, wherever possible, to find a grain of the mineral 
 in question large enough entirely to hold a small drop of the 
 reagent. 
 
 Reagents. The following reagents have been used, to greater or 
 less extent : the first eight have been found most useful. With 
 further work, undoubtedly other reagents will be found to prove 
 valuable in special cases. The symbols or abbreviations in the 
 list below are the same as those used in the determinative tables 
 of this book. 
 
 LIST OF REAGENTS 
 
 1. HN0 3 Concentrated nitric acid diluted with equal volume of water. 
 
 2. HN0 3 cone. Concentrated nitric acid. 70% (sp. gr. 1.42). 
 
 3. KCN 20% solution. 
 
 4. HC1 Concentrated hydrochloric acid diluted with equal volume of water. 
 
 5. HC1 cone. Concentrated hydrochloric acid. 37% (sp. gr. 1.19). 
 
 6. Aq. Reg. Freshly made Aqua Regia (3 HC1 + HN0 3 ). 
 
 7. FeCl 3 20% solution. 
 
 8. KOH Concentrated solution. 
 
 9. NaOH Concentrated solution. 
 
 10. NH 4 OH 28% solution. 
 
 11. (NH^S*. 
 
 12. Iodine Solution in alcohol. 
 
 13. KsFe(CN) 6 20% solution. 
 
 14. K4Fe(CN) 6 20% solution. 
 
 15. H 2 S04 dilute or concentrated. 
 
 16. AgN0 3 3% 10% solution. 
 
 17. KClOs Saturated solution, followed by cone. H 2 S04. 
 
 The reagents are used cold, unless otherwise stated. Hot 
 reagents are desirable in certain cases, though they usually have 
 to be applied to the whole surface, thus making it necessary to 
 re-polish the specimen for further examination. - 
 
WHITE/ COLOR 
 
 MINERAL COMPOSITION AND IDENTITY 
 
 
 
 THE microscopic examinatioiUiOf polished surfaces is competent 
 to detect mechanical mixtures of minerals, even when exceedingly 
 minute. Moreover, it may be relied on to perceive even very 
 slight color differences, due not to mechanical mixture, but to 
 variation in chemical composition. Finally, specimens, which 
 have been shown by crystallographic or other means to belong 
 to the same species and which appear physically similar under the 
 microscope, may show differences in microchemical behavior 
 which must signify that the mineral in question is actually variable 
 in chemical composition. It must be borne in mind, however, 
 that color differences may also be caused by difference in perfec- 
 tion of polish; the variations due to actual differences in composi- 
 tion, however, are ordinarily exceedingly slight, while those due to 
 imperfection of surface may be avoided by taking sufficient care in 
 polishing, but with growing experience due allowance can be made 
 for the effect produced on the true color by minute pits and 
 scratches. 
 
 For purposes of discussion of composition and identity, miner- 
 als may conveniently be divided into a number of groups according 
 to the prevailing view. 
 
 1. Minerals of thoroughly established identity and constant 
 composition, such as pyrite or chalcopyrite. 
 
 2. Minerals of definitely established identity and variable com- 
 position, such as tetrahedrite or polybasite. 
 
 3. Minerals of fairly well established identity, supposed to be 
 constant in composition, such as mohawkite. 
 
 4. Minerals described as definite species though believed by 
 some to be mixtures, like cubanite. 
 
 With regard to these groups, mineralographic examination leads 
 to the following conclusions. 
 
 1. The validity of this group is clearly established. 
 
 2. Some members of this group have been shown to owe their 
 variable composition to the presence of other elements in chemical 
 combination with the normal constituents of the mineral. This 
 
 33 
 
34 MICROSCOPICAL DETERMINATION 
 
 variation in some cases does not appear to affect the physical or 
 microchemical properties. Here, for example, belongs pyrrhotite, 
 which has a variable amount of sulphur in excess of FeS, but 
 which does not show any perceptible variation in properties and 
 appearance under the microscope. Thus it appears that in the 
 case of solid solutions, such as pyrrhotite has been shown to be, the 
 variation may not appear in any way other than by a chemical 
 analysis. In other cases there are small but perceptible differences, 
 as in the case of polybasite, which shows by analysis a rather 
 wide variation in composition, as regards the ratio of bases 
 present. 
 
 The analyses of the tetrahedrite-tennantite series (Cu 8 Sb 2 S 7 - 
 Cu 8 As2S 7 ) are so variable that Hintze and Dana give different 
 formula, and even then have to assume that various metals 
 replace the copper to a greater or less extent. As a matter of 
 fact, microscopic examination of many specimens shows that 
 these minerals, even in good crystals, have a strong tendency to 
 be intergrown with other sulphides, thus giving, in most of these 
 instances, a simple explanation of the variation in composition 
 shown by the analyses, and also accounting for many of the extra 
 metals present. Pure material of this series shows but slight 
 variation in color, the pure arsenic and pure antimony compounds 
 being slightly though distinctly different, while the intermediate 
 members of the series frequently cannot, without very close 
 scrutiny, be distinguished from either end member. The copper 
 may be in part replaced by silver, without change in color, though 
 the microchemical properties are affected. It is quite probable 
 that other metals may occur similarly, without changing the phys- 
 ical properties of the mineral. 
 
 Steinmannite, which is galena with chemically combined arsenic 
 and antimony, exactly resembles galena in physical properties, 
 but is somewhat different in microchemical behavior. 
 
 Many analyses of galena show the presence of other elements, 
 such as arsenic, antimony, silver and sometimes bismuth, which 
 the microscope has shown to be chemically combined with it, 
 and which change only the microchemical properties. Some so- 
 called argentiferous galenas are found on microscopic examination 
 to contain small amounts of distinct silver minerals, which account 
 for the silver content in these cases. 
 
 The various cobalt and nickel arsenides (such as smaltite, skut- 
 
OLOR 
 
 OF THE OPAQUE MINERALS 35 
 
 terudite, chloanthite, etc.) occur in mixtures with all proportions 
 of these various minerals, along with minerals not belonging to 
 the series. The crystals appear to be zoned, and this structure is 
 generally revealed by etching, if not visible before. It is also sug- 
 gested by differences in solubilities that have been noted in pre- 
 vious chemical work on these hiinerals. Inclusions of minerals not 
 of the series have a strong tendency to take the form of suspended 
 droplets or blebs in the host, like an emulsion. It is accordingly 
 not surprising that analyses, even of crystals, have given variable 
 results, and consequently some of the formulae assigned to these 
 minerals are probably wrong. 
 
 Other members of the second group owe their supposed variation 
 to mechanical admixture, such as bornite. Analyses of bornite have 
 varied between wide limits, and though it has long been recognized 
 that this variation is usually due to mechanically admixed chal- 
 cocite, it has been a great question whether bornite really is of 
 constant composition or not. In 1905, Harrington 18 analyzed pure 
 material from several localities, both massive and in crystals, 
 and established the definite formula CusFeS^ which has since 
 been generally accepted. Mineralographic study has shown that 
 very rarely indeed is absolutely pure bornite found in amounts 
 large enough to analyze, and that the usual impurity is chalcocite, 
 either intergrown with it, or formed in it as the result of altera- 
 tion, though chalcopyrite is not uncommon, and other sulphides 
 also occur. A large area of especially pure massive bornite, 
 subjected to a careful geometric analysis on the polished surface, 
 revealed only about 0.3 per cent of impurity, quite uniformly dis- 
 tributed through the material and consisting of chalcocite, chal- 
 copyrite, tetrahedrite and galena. Selected portions of this 
 material were sent for analysis to Dr. E. T. Allen of the Geo- 
 physical Laboratory in Washington. Dr. Allen's results 1 agreed 
 with Harrington's and also with determinations which he made on 
 some of Harrington's material and on other specimens of pure 
 bornite, thus positively confirming Harrington's formula for the 
 mineral. Furthermore, mineralographic examination of polished 
 surfaces of bornite from at least 30 different localities has revealed 
 only an exceedingly slight variation in color, and practically none 
 in microchemical behavior. 
 
 In the face of all this concordant testimony and of the fact, 
 noted by Harrington and confirmed by mineralographic examina- 
 
36 MICROSCOPICAL DETERMINATION 
 
 tion of bornite crystals from Butte, Montana, and Cornwall, 
 England, that many crystals of this mineral are pure externally 
 but contain much intermixed chalcocite or chalcopyrite in the 
 interior, the conclusion by Kraus and Goldsberry 23 that bornite 
 is of variable composition must be regarded with doubt, especially 
 as it appears that, although they sought to establish the purity 
 of their material by microscopic examination with reflected light, 
 they unfortunately failed to examine the material actually 
 analyzed. Rogers 36 has come to the conclusion that the variability 
 of bornite is due to the solid solution of chalcocite in bornite, and 
 considers that Kraus and Goldsberry have proved that bornite 
 really is variable in composition. 
 
 This occurrence of an impure basal or central portion in crys- 
 tallized material is found to be surprisingly common in most 
 sulphides, and is a possible source of error which should be guarded 
 against by selecting for analytical purposes only material that has 
 been very carefully and thoroughly examined microscopically 
 in several crystallographic directions. 
 
 3. Minerals of this group have been shown in many cases to be 
 mechanical mixtures : mohawkite or schapbachite, for instance. 
 
 4. Some minerals of this group have been definitely shown to be 
 mechanical mixtures, like cubanite, thus confirming the prevalent 
 opinion about them. 
 
 Sphalerite very frequently occurs filled with an " emulsion " 
 of minute blebs or crystals of chalcopyrite, often arranged along 
 crystallographic directions in the sphalerite. These would not 
 appear in the hand specimen, and probably would not be visible 
 even in thin section, especially if, as is apt to be the case, the 
 sphalerite were rich in iron, and, hence, very dark. This same 
 " emulsion " structure occurs in much greater perfection with 
 bornite in chalcocite. Here there are often beautiful patterns 
 of bornite droplets in the chalcocite, along both straight and 
 curved lines. The droplets are often elongated in one direction, 
 adding to the variety of the pattern, and approaching the typical 
 " eutectic " structure. 
 
 OBSERVED MIXTURES 
 
 The following supposed mineral species, some of which have 
 been regarded with doubt by mineralogists, have been shown 
 with more or less certainty by mineralographic study to be mixtures 
 
OLOR 
 
 OF THE OPAQUE MINERALS 37 
 
 of two or more minerals. Some of these constituents are known 
 while some, mainly because of their minute size, are as yet uniden- 
 tified and it is very probable that several of them are actually 
 new species. Unknown constituents have been treated at the 
 appropriate places in the determinative tables. 
 
 Algodonite. A mixture, or yatergrowth of two unknown con- 
 stituents, one creamy, the other grayish. The gray is rather less 
 in amount, on the average. Determined in two specimens. 
 
 Alloclasite. Probably glaucodot, or a similar mineral, with 
 blebs of bismuth (?) and a bluish gray, soft mineral, scattered 
 through it. There is also native gold, but this was recognized 
 in the analyses. Only one piece was polished, but the material 
 is typical, and undoubtedly the finding is reliable. The specimen 
 appears like an emulsion of the softer minerals in the glaucodot. 
 
 Animikite. Only one small specimen studied, but appears to 
 be a mixture of several minerals. Possibly the study of more 
 material would establish its identity more fully. 
 
 Barnhardtite. A mixture resulting from the alteration of chal- 
 copyrite to covellite and chalcocite. This has previously been 
 recognized as a probable mixture, and the present determination, 
 made on a piece of the type material, confirms this conclusively. 
 
 Brogniardite. Appears in some specimens labelled brogniardite 
 to be a mixture of ruby silver, galena (?) and possibly miargyrite; 
 other specimens show a distinct mineral close to argentiferous 
 jamesonite. Very dubious. 
 
 Carrolite. Probably linnaBite with intergrown bornite and 
 chalcopyrite. Differs only slightly from linnseite from Siegen, 
 agrees with linnseite from Mine La Motte, Missouri, and is 
 intimately intergrown with enough of the copper minerals to fur- 
 nish the copper required by the formula ascribed to carrolite. 
 This determination is not final, but is highly probable. 
 
 Chalcopyrrhotite. Probably a mixture of chalcopyrite with 
 pyrrhotite, and some chalmersite. This is not certain, but is 
 highly probable. 
 
 Cubanite. A mixture of pyrite or pyrrhotite with chalcopyrite. 
 Four specimens, from different localities, were examined and none 
 was homogeneous, so the conclusion that cubanite is not a definite 
 mineral but a mixture is probably reliable. 
 
 Domeykite. Three specimens have the same characteristics as 
 algodonite. Another has mixture of cream and purple. 
 
38 MICROSCOPICAL DETERMINATION 
 
 Harrisite. A pseudomorph of chalcocite after galena. 
 
 Homichlin. Chalcopyrite altering to limonite, with a little 
 chalcocite. This was determined on a large piece from the type 
 locality, and is surely reliable. 
 
 Keweenawite. A mixture of smaltite, niccolite, and domeykite, 
 with usually a little stromeyerite (?) . Determined from two pieces, 
 one identified by Kcenig himself as keweenawite, and is conclusive. 
 
 Klaprotholite. Alteration product of an unknown creamy 
 mineral (?) with bismuth (?) and covellite. This was determined 
 on only one specimen and may not be reliable, though as the 
 material came from the type locality, the validity of klaprotholite 
 seems doubtful. 
 
 Kobellite. Intergrowth of galena with a mineral like bismuth- 
 inite or stibnite. Also determined on only one piece, which may 
 not have been representative. 
 
 Mohawkite. Mixture of two unknown constituents, one 
 creamy and one grayish, like those in algodonite, but with more 
 of the gray, and the two (algodonite and mohawkite) may not 
 be exactly the same, though they appear very similar. 
 
 Plenargyrite. Mixture of two unknown components, one soft 
 and bluish, the other harder and creamier. 
 
 Schapbachite. Practically the same as plenargyrite, but with 
 slightly different properties. 
 
 Smaltite. The group of cobalt and nickel arsenides shows prob- 
 able zoning of different members in any one crystal, so that analyses 
 cannot be relied on to show the composition of individual species. 
 
 Tapalpaite. A mixture of creamy and grayish unknown com- 
 ponents (?) Perhaps the creamy part is the true mineral. One 
 good specimen studied. 
 
 Temiskamite. A mixture of maucherite and niccolite, with a 
 little cobaltite. Determined from the type specimen, and surely 
 reliable. 
 
 PROBABLE MIXTURES AND DOUBTFUL MINERALS 
 
 The following names have been ascribed to certain supposed 
 mineral species which are regarded in the standard text-books 
 as doubtful. None of these has been examined by the author, 
 but the similarity of the evidence in many cases to that for sup- 
 posed minerals which actually have been examined, tends to 
 indicate that examination would confirm the suspicion, and ac- 
 
WHITE/ COLOR 
 
 OF THE OPAQUE MINERALS 
 
 39 
 
 cordingly they are tentatively placed under this heading, pending 
 investigation. The probable nature of each is indicated after 
 the name. > indicates "altering to " or " altered to." For mean- 
 ing of abbreviations see p. 46. 
 
 Acanthite = Distorted argentite" 
 Alisonite = gn > cv or cc 
 Antimon-luzonite = famatinite? 
 Arite = NiSb and NiAs (mixture) 
 Arsenotellurite - Te, As, C? ? 
 Barracannite impure material 
 Beyrichite = impure polydymite 
 Blueite = py 
 Bolivianite - Ag, Sb, S? 
 Bolivite impure material 
 Bravoite impure material 
 Cantohite = bn cv 
 Castillite = bn and Ag? 
 Clarite = en 
 Clayite - Pb, Cu, Sb, As, S 
 
 (altn. prod.?) 
 
 Coolgardite impure material 
 Corynite - Ni, (Sb As), S 
 Crucite = arsenopyrite > hem- 
 atite 
 
 Cuproplumbite = gn > cc and cv 
 Daleminzite = Ag 2 S (orth.) 
 Danaite = Cobaltif . arsenopyrite 
 Dimorphite As 4 S 3 ? 
 Ducktownite impure material 
 Durfeldtite - (Ag, Pb, Sb, S)? 
 Fieldite = impure td. 
 Folgerite = pentlandite 
 Grunauite= impure polydymite? 
 Guadalacazarite = Hgs and ZnS? 
 Gunnarite = pentlandite 
 Heazlewoodite = pentlandite 
 Histrixite Cu5Fe 5 Bii4Sb 4 S37 (mix- 
 ture)? 
 
 Horbachite -4 Fe 2 S 3 Ni 2 S 3 (mix- 
 ture) . 
 
 Huascolite = gn and si? 
 
 Jaipurite CoS? 
 
 Joseite = tetradymite? 
 
 Kaneite = Mn, As ? ? 
 
 Kilbrickenite = geocronite 
 
 Kroeberite (not analyzed) 
 
 Lautite = en and As 
 
 Ledouxite impure material 
 
 Leviglianite Ag2S orth. and Fe? 
 
 Marrite (not analyzed) 
 
 Metastibnite St^Ss (amor- 
 phous)? 
 
 Miillerine = impure krennerite 
 
 Nepaulite = td 
 
 Orileyite = impure domeykite? 
 
 Osbornite - Ca, Ti?, S, O (me- 
 teoric) 
 
 Pacite = impure arsenopyrite? 
 
 Plumbomanganite (MnPb), S? 
 
 Plumbostannite-Pb, Sn, Sb, S? 
 
 Quirogite = impure galena 
 
 Silaonite impure material 
 
 Silverphyllinglanz = nagyagite?. 
 
 Sommarugaite = Aurif. gers- 
 dorffite 
 
 Tombazite = py 
 
 Valeriite - Cu, Fe, Al, Mn 2 , H 2 , 
 O, S?? 
 
 Warrenite = jamesonite and 
 zinkenite 
 
 Wehrlite - Bi, Te, S, Ag? 
 
 Whartonite = pyrite 
 
 Wolfachite near corynite 
 
 Youngite - Pb, Zn, Fe, S, Mn? 
 
 Zorgite = clausthalite + uman- 
 gite? 
 
PLAN OF CLASSIFICATION 
 
 THE plan of classification in the tables that follow is based 
 first of all on the color of polished minerals as seen under the 
 microscope. The next test is relief or hardness. Subordinate to 
 relief in part of the tables, color is again employed as a basis for 
 subdivision. Microchemical tests come last. 
 
 COLOR 
 
 The opaque minerals are here divided into three main groups 
 primarily by determination of color that is, the color of the min- 
 eral as observed alone under the microscope, not compared with 
 anything else. If the mineral has a decided color, it is called 
 colored. If very pale colored, or white, it is classified as white. 
 If distinctly gray, it is put under that heading. 
 
 Colored. If a mineral has a distinct color, its identification 
 is very simple, as there are comparatively few colored opaque 
 minerals. Chalcopyrite, for instance, is yellow, covellite is blue, etc. 
 
 White. If the mineral is white, or approximately so, the identi- 
 fication on the polished surface is more complicated, because a 
 large majority of the sulphides fall in this class. It is, therefore, 
 necessary to establish three subdivisions on the basis of hardness 
 or relief. The subdivision with high relief needs no further color 
 determination, except incidentally, but the other two, medium 
 and low relief, are so extensive as to require still further subdivi- 
 sions by color. This is made by color comparison with a standard, 
 as described on page 26. It is exceedingly important that this 
 step be made with care, because of the close similarity in appear- 
 ance of many minerals. In fact, this is one of the most important 
 and effective points in the classification, and without it the task 
 of identifying a mineral in either of these groups would be tedious 
 and difficult. With practice, the differences between the color 
 subdivisions are easily recognized, the eye rapidly acquiring 
 facility in detecting variations. To aid identification, in the case 
 of minerals whose tints fall between two of the established groups, 
 the mineral description in full is put in the group it appears to 
 approach most closely and a reference to this is given in the ap- 
 propriate place in the other group. Unfortunately, there are 
 
 40 
 
WHITE/ COLOR 
 
 ^^^^^IM^MMi^^^^^ ^v^ -^ 
 
 OF THE OPAQUE MINERALS 41 
 
 a number of such minerals, but it is believed that with the full 
 cross-referencing no trouble will arise from this source. 
 
 The secondary subdivisions by color, established by this com- 
 parison, are as follows: 
 
 Galena White. This term has been used to denote the color of 
 galena itself, and in this group are placed, in one subdivision, all 
 minerals that appear pure whitfe against galena, and in the other, 
 all those the same color as galena, or only very slightly different. 
 
 Creamy White. This is approximately the color of pure silver 
 compared with galena, and in this group are placed all minerals 
 appearing creamy white against galena. A division has been made 
 of this group, using silver as a standard, into minerals paler than 
 silver, or the same color, and minerals darker than silver. 
 
 Bluish White. Minerals appearing bluish white against galena. 
 Many of these are transparent. 
 
 Pinkish White. Minerals appearing pinkish white against galena. 
 
 Grayish White. Minerals appearing grayish white or grayish- 
 greenish white against galena. 
 
 Other color values within the limits of white exist, but they are 
 too indefinite for separate grouping and are noted by a qualifying 
 adjective in the description of the mineral's color. 
 
 Gray. If a mineral is distinctly gray, it may be compared 
 with dark sphalerite, though this is not usually necessary, and may 
 be used as a supplementary test. Some hard white minerals 
 polish with difficulty, and often appear gray, because finely pitted. 
 
 Transparent and gangue minerals. Some sulphides are trans- 
 parent. This property may be detected by observing with oblique 
 light, which may be obtained by temporarily stopping the aper- 
 ture of the vertical illuminator. Transparent red minerals, like 
 cuprite or ruby silver, reflect the complement of their transmitted 
 color and appear bluish. All the transparent sulphides have a 
 very high index of refraction, and probably for this reason appear 
 bright on the polished surface by vertically reflected light. Sphal- 
 erite is the darkest of these and appears grayer than any other 
 sulphide. Most gangue minerals are transparent, and practically 
 all appear decidedly darker than sphalerite, which thus occupies 
 an intermediate position. The transparent gangue minerals, 
 usually with a fairly low index of refraction, appear dark gray 
 because the light in large part penetrates the grain and is dispersed 
 and lost on the irregular lower surface, while only a small portion 
 is reflected back from the polished face. 
 
42 MICROSCOPICAL DETERMINATION 
 
 Effect of surface on color. Poorly polished surfaces appear 
 darker than smooth ones, and pits on the polished surface appear 
 black, because most of the light is scattered from the uneven 
 bottom and sides. Minerals with high relief, surrounded by much 
 softer ones, appear to be surrounded by a black rim, due to the 
 sloping contact between the higher and lower mineral, which 
 deflects the light obliquely.. 
 
 HARDNESS 
 
 The second main division is based on hardness, as determined 
 either by the actual relief of a mineral on the polished surface 
 against a known constituent, by the character of the polish ob- 
 tained, or by scratching directly under the microscope, with a 
 fine needle point. By this means, three main groups are estab- 
 lished, which are very satisfactory for rapid determination. Cross- 
 referencing avoids error in cases of doubt as to the group in which 
 a mineral actually falls. 
 
 1. Hardness High. Minerals which are distinctly hard, .stand 
 up above most minerals, except quartz, and are scratched with 
 difficulty, if at all, by the needle. Minerals from 4.5 to 5.5 in the 
 scale of hardness can be grooved by a moderate pressure of the 
 needle point, but do not show a typical scratch. Examples: 
 pyrite, magnetite. 
 
 2. Hardness Medium. Minerals which are not scratched by 
 the weight of the handle alone, with no extra pressure applied, but 
 are readily scratched by moderate pressure on the needle. Ex- 
 amples: chalcopyrite, enargite, tetrahedrite. 
 
 3. Hardness Low. Minerals easily scratched by the weight 
 of the handle alone. Examples: chalcocite, galena, bornite. 
 
 MICROCHEMICAL TESTS 
 
 The final determinative tests are microchemical, as in most 
 cases a mineral cannot be identified by its physical properties 
 alone. These separate the larger divisions into small groups in 
 which any one mineral may be readily identified. The method 
 of using these tests has already been described (p. 30). 
 
 EXPLANATION OF TABLES 
 
 Directions for Use. The main divisions of the classification, 
 colored, white, and gray, are indicated by the tabs of a thumb index 
 at the top of the book. These are the only tabs on the upper margin 
 
OF THE OPAQUE MINERALS 43 
 
 of the page, all others being on the outer margins. The first step in 
 usirjg the tables is to open them to the beginning of one of the main 
 divisions, by holding down with the thumb the appropriate tab. 
 This exposes the first subdivision, marked by a series of tabs on 
 the outer margin of the right hand page. One of these tabs is then 
 similarly held down, and the tables opened to the page carrying 
 that tab, revealing the tabs^of the second subdivision on the 
 outer margin of the left hand page. This procedure is continued, 
 the tabs alternating from right to left, until no more new sets 
 appear, showing that the last subdivision has been reached. This 
 is usually indicated by negative reactions on the left page and 
 positive reactions on the right page; as, for instance, KCN neg. 
 on the left and KCN on the right. (See pages 116-117.) 
 
 When this stage is reached, the full descriptions of the desired 
 group of minerals will be found. A mineral name, followed by a 
 reference to another page, indicates that the mineral does not 
 properly belong in this group, but its full description may be 
 looked up on the page indicated to make entirely sure in doubtful 
 cases that it is not the mineral undergoing test. In running 
 down a mineral, the tables must always be opened to the page 
 which carries the tab for the test just made, and the next test to 
 be applied is indicated by the tabs on the opposite margin as the 
 book is held open. 
 
 Examples. One or two examples will show clearly how the 
 tables are intended to be used. 
 
 1. Suppose a mineral has been polished and inspected under 
 the microscope. It appears yellow; therefore, hold down the 
 colored tab and open to that page (p. 57). It is yellow, so 
 hunt on the right hand margin for yellow. Place the thumb 
 on this tab, and open to that page (p. 63). There are no tabs 
 on the left, so the mineral in question must be found on the pages 
 now open. The right hand page is headed pale, the left hand, 
 bright. The mineral appears bright yellow, so it is sought on 
 the left page, where are found chalcopyrite, gold, and yellowish 
 and orange " bornite." Looking up the reference to yellowish 
 and orange " bornite," one finds that these are not really bright 
 yellow but always orange or brownish, so they may be eliminated. 
 Under Diff. in the two minerals remaining, it is seen that they 
 are distinguished from each other by color, behavior with KCN 
 and character of surface. The chemical test is surest so KCN 
 
44 , MICROSCOPICAL DETERMINATION 
 
 is tried; it roughens and dissolves the surface of the yellow min- 
 eral, thus proving it to be gold. 
 
 2. Taking a white mineral this time, place the thumb on the 
 white tab, open the book to that page (p. 81), and look on the right 
 hand margin. Hardness appears to be the next test. The min- 
 eral appears smooth, and is easily scratched with a needle, showing 
 it to have low hardness. Place the thumb on the tab hardness 
 low, and open to that page (p. 143). Looking on the left hand 
 margin, it is seen that the outer tabs refer to color, compared 
 with galena, so the mineral is compared with galena and found 
 to look faintly bluish. Place the left thumb on the tab marked 
 bluish white, and open to the page carrying that tab (p. 114). 
 Look on the right again. The next test is with HNO 3 , so make 
 that test, finding that the mineral is attacked by HNO 3 , noting 
 that it is plated almost instantly with a film that looks like metallic 
 copper and that part of this film dissolves off quickly, and the 
 mineral turns dark; in other words, HNO 3 gives a positive reac- 
 tion, so hold down the HNO 3 tab and open to that page (p. 117). 
 There are no more tabs on the left, so the final pages have been 
 reached. The left says KCN neg., the right says KCN, so test with 
 KCN, finding that the mineral is rapidly etched and somewhat 
 darkened. This puts it on the right hand side with a choice of 
 cuprite, stromeyerite and chalcocite. The descriptions of these 
 minerals indicate that chalcocite turns darker blue and effervesces 
 with HN0 3 , which rules it out; stromeyerite does not act with 
 HNO 3 as the mineral in question has behaved, whereas cuprite 
 fits the case exactly. A final assurance may be made by prov- 
 ing that the mineral is transparent red by oblique light, since chal- 
 cocite and stromeyerite are both opaque. 
 
 These directions have been made very explicit so that there 
 shall be no chance for mechanical error in using the tables. To 
 make sure no mistake or omission has occurred in running down 
 a mineral, the sequence of tests identifying a given group is placed 
 in the upper corner of the left hand page, so they all may be seen 
 together, and checked up. By this means, the fewest possible tests 
 need be applied, resulting often in a considerable saving of time. 
 When the full description of the mineral is reached, other tests may, 
 of course, be applied to check up the accuracy of the determination. 
 
 Cross-References. As previously explained, numerous cross- 
 references have been made in the case of minerals on the border 
 
OF THE OPAQUE MINERALS 46 
 
 line between two or more colors or tints, or two classifications 
 of relief, or with doubtful chemical behavior. That is, if a min- 
 eral might conceivably, be called either pale yellow, or cream colored, 
 or white, like pyrite, for example, its full description is placed 
 under the heading cream and references to this are given in the 
 proper place under each of 'the other two headings, so it can be 
 found if the observer -assigns "it to any one of these colors. Sim- 
 ilarly, a mineral like bournonite, which is intermediate in hard- 
 ness between minerals of medium and of low relief, probably 
 nearer medium, is fully described under hardness medium, and 
 a reference given to this in the appropriate place under hardness 
 low. The cross-referencing has been especially complete among the 
 white and faintly tinted minerals, as here the color differences are 
 very slight at best, and some intermediate tints are indefinite 
 even to the practiced eye. 
 
 Abbreviations. The abbreviations on the tabs are as follows: 
 HN0 3 is taken as an example; abbreviations for other reagents 
 may be found on page 32. 
 
 Abbreviation Meaning 
 
 HN0 3 . - Attacked by HN0 3 (visibly changed or af- 
 
 fected). 
 
 HNO 3 neg. - Not attacked visibly by HNO 3 . 
 
 Fumes HN0 3 . Tarnished by the fumes of HN0 3 but not 
 visibly attacked by the liquid, so that a ring 
 of tarnish is formed around a clear spot, 
 which was covered by the reagent. 
 
 Eff. HN0 3 . Attacked by HNO 3 , with effervescence. 
 
 No Eff.HNO 3 . Attacked by HNO 3 , but without effervescence. 
 
 In the descriptions of the minerals, the following abbreviations 
 are used: 
 
 Col. Color, including transparency. 
 
 Occ. Habit of occurrence, if distinctive (such as platy, or 
 in crystals or crystalline grains). 
 
 Hard. Hardness. 
 
 Surf. Character of polished surface. 
 
 H. Hardness as given in Dana's System of Mineralogy; 
 supplemented by comparison, where possible, with relative hard- 
 ness to accompanying minerals. 
 
46 
 
 MICROSCOPICAL DETERMINATION 
 
 Chem. Microchemical tests. 
 
 Diff. Distinctive characters, physical or chemical, which 
 serve to distinguish a mineral from others of the group. 
 . - Negative test. 
 
 The following abbreviations have been found convenient for 
 designating some of the commoner sulphides: 
 
 PY = pyrite 
 cp = chalcopyrite 
 bn = bornite 
 cc = chalcocite 
 cv = covellite 
 td = tetrahedrite 
 
 en = enargite 
 si = sphalerite 
 gn = galena 
 po = pyrrhotite 
 mg = magnetite 
 G= gangue, including all the 
 transparent, non-metallic 
 minerals. 
 
WHITE/ COLOR/ 
 
 OUTLINE OF THE CLASSIFICATION 
 
 (Parentheses around a mineral indicate a cross reference, and that the full description 
 is to be found elsewhere in the tables.) & 
 
 1. COLORED 
 
 1. BLUE 
 
 1. BRIGHT 
 
 1. Covellite 
 
 2. (Chalcocite) 
 
 2. PALE 
 
 g ee: WHITE HARDNESS Low BLUISH WHITE. 
 
 2. PURPLE 
 
 1. BRIGHT 
 
 1. Umangite 
 
 2. Rickardite 
 
 3. (Purplish brown " bornite ") 
 
 2. PALE 
 
 1. (Purple "galena") 
 
 2. (Color adoite) 
 
 3. YELLOW 
 
 1. BRIGHT 
 
 1. Chalcopyrite 
 
 2. Gold 
 
 3. (Orange "bornites") 
 
 2. PALE 
 
 1. HNO 3 NEG. 
 
 1. Millerite 
 
 2. (Pyrrhotite) 
 
 3. (Sulvanite) 
 
 4. (Chalmersite) 
 
 5., (Gold, var. electrum) 
 
 2. HN0 3 
 
 1 . (Marcasite) 
 
 2. (Pyrite) 
 
 . 3. (Bismuth) 
 4. BROWN 
 
 1. HNO 3 NEG. 
 
 1. Orange * bornites" 
 
 2. (Pyrrhotite) 
 
 3. (Kalgoorlite) 
 
 2. HN0 3 
 
 1. Purplish brown "bornite" 
 
 2. Sternbergite Frieseite 
 
 3. Bornite 
 
 4. Unknown brown, Bisbee 
 
 5. (" Bronze enargite ") 
 
 47 
 
48 MICROSCOPICAL DETERMINATION 
 
 5. PINK 
 
 1. HNO 3 NEG. 
 
 1. (Luzonite) 
 
 2. (Unknown pink with mohawkite) 
 
 2. HNO 3 
 
 1. KCNNEG. 
 
 1. Niccolite 
 
 2. Breithauptite 
 
 3. (Maucherite) 
 
 4. (Bismuth) 
 
 2. KCN 
 
 1. Copper 
 
 2. (Bornite) 
 
 3. (Algodonite) 
 
 4. (Whitneyite) 
 
 5. (Cobaltite) 
 
 6. (Famatinite) 
 
 6. CREAM 
 
 1. HARDNESS HIGH 
 
 1. HN0 3 N EG . 
 
 1. Pyrrhotite. 
 
 2. Unknown pink with mohawkite 
 
 2. HN0 3 
 
 1. SURFACE DULL 
 
 1. Pyrite 
 
 2. Marcasite 
 
 2. SURFACE SHINY 
 
 1. Linnseite 
 
 2. Maucherite 
 
 3. Hauchecornite 
 
 4. (Pentlandite) 
 
 5. (Niccolite) 
 2. HARDNESS MEDIUM 
 
 1. HNOsNEG. 
 
 1. Sulvanite 
 
 2. Chalmersite 
 
 3. (Millerite) 
 
 4. (Unknown, Butte, N 13) 
 
 5. (Pyrrhotite) 
 
 6. (Delafossite) 
 
 2. HN0 3 
 
 1. " Bronze enargite " 
 
 2. Algodonite (Cream) 
 
 3. Mohawkite (Cream) 
 
 4. Whitneyite 
 
 5. (Pentlandite) 
 
 6. (Aikinite) 
 
 7. (Niccolite) 
 
 8. (Linnaeite) 
 
 9. (Copper) 
 
 10. (Hauchecornite) 
 
WHITE/ COLOR 
 
 ^^^^^^^^^^^^^^ 
 
 OF THE OPAQUE MINERALS 49 
 
 3. HARDNESS Low 
 
 See: WHITE HARDNESS Low CREAMY WHITE. 
 
 2. WHITE 
 
 1. HARDNESS HIGH 
 
 1. HNO NEG. 
 
 1. HCL CONC. NEG. t " 
 
 1. Rutile 
 
 2. Ilmenite 
 
 3. Hematite 
 
 4. (Pyrrhotite) 
 
 5. (Franklinite) 
 
 2. HCL CONC. 
 
 1. [ Magnetite 
 
 2. Sperrylite 
 
 3. (Unknown pink with mohawkite) 
 
 2. NOEFF. HNO 3 
 
 1. HCL UNCHANGED 1' 
 
 1. No EFF. AQ. REG. 
 
 1. AQ. REG. NEG. 
 
 1. Cobaltite 
 
 2. (Linnseite) 
 
 2. AQ. REG. 
 
 1. Glaucodot 
 
 2. (Pentlandite) 
 
 2. EFF. AQ. REG. 
 
 1. FECL S NEG. 
 
 1. Lollingite 
 
 2. Ullmannite 
 
 3. (Arsenopyrite) 
 
 2. FECLa 
 
 1. Chloanthite 
 
 2. Rammelsbergite 
 
 2. HCL TURNS YELLOWISH GREEN 
 
 1. Gersdorffite 
 
 3. EFF. HNO 3 
 
 1. AQ. REG. NEG. 
 
 1. (Pyrite) 
 
 2. (Marcasite) 
 
 3. (Argyropyrite) 
 
 2. AQ. REG. 
 
 1. FECL 3 NEG. 
 
 1. Arsenopyrite 
 
 2. Kallilite 
 
 3. Willyamite 
 
 4. Poly dy mite 
 
 2. FECL 3 
 
 1. Safflorite 
 
 2. Smaltite 
 
 3. Skutterudite 
 
 4. (Maucherite) 
 
50 MICROSCOPICAL DETERMINATION 
 
 2. HARDNESS MEDIUM 
 
 1. GALENA WHITE 
 
 1. KOHNEG. 
 
 1. Chalcostibite 
 
 2. (Bournonite) 
 
 3. (Polybasite) 
 
 4. (Geocronite) 
 
 5. (Kallilite) 
 
 2. KOH 
 
 1. Berthierite 
 
 2. Guejarite 
 
 2. CREAMY WHITE 
 
 1. No EFF. HNO 3 
 
 1. Pentlandite 
 
 2. (Sulvanite) 
 
 3. (Chalmersite) 
 
 4. (" Bronze Enargite ") 
 
 5. (Berthierite) 
 
 6. (Linnaeite) 
 
 7. (Hauchecornite) 
 2. EFF. HN0 3 
 
 1. Argyropyrite 
 
 2. Aikinite 
 
 3. (Domeykite) 
 
 4. (Algodonite, Cream) 
 
 5. (Mohawkite, Cream) 
 
 6. (Whitneyite) 
 , 7. (Kallilite) 
 
 3. PINKISH WHITE 
 
 1. HN0 3 NEG. 
 
 1. Luzonite 
 
 2. (Enargite) 
 
 2. HNO 3 
 
 1. Famatinite 
 
 2. (Argyropyrite) 
 
 3. (Geocronite) 
 
 4. (Breithauptite) 
 
 4. GRAYISH WHITE 
 
 1. HNO 3 NEC. 
 
 1. KCN NEC. 
 
 1. Bournonite 
 
 2. Tenorite 
 
 3. Delafossite 
 
 4. (Tetrahedrite) 
 
 5. (Regnolite) 
 
 2. KCN 
 
 1. (Polybasite) 
 
 2. (Enargite) 
 
 3. (Argyrodite) 
 
WHITE/ COLORIp/ 
 
 OF THE OPAQUE MINERALS 51 
 
 2. FUMES HNO 3 
 
 1. KCN NEG. 
 
 1. Tetrahedrite 
 
 2. Tennantite 
 
 3. Hauerite 
 
 4. (Bournonite) 
 
 2. KCN 
 
 !.* Enargite 
 
 3. HN0 3 
 
 1. KCN NEG. 
 
 1. Algodonite (Gray) 
 
 2. Polytelite 
 
 3. Alabandite 
 4 (Geocronite) 
 
 5. (Freibergite) 
 
 6. (Baumhauerite) 
 
 7. (Mohawkite gray) 
 
 8. (Crookesite) 
 
 9. (Plagionite) 
 
 10. (Stylotypite) 
 
 11. (Bournonite) 
 
 2. KCN 
 
 1. Mohawkite (gray) 
 
 2. Stylotypite 
 
 3. (Plagionite) 
 
 3. HARDNESS Low 
 
 1. GALENA WHITE 
 
 1. PURE WHITE 
 
 1. HCLNEG. 
 
 1 . G alenobismutite 
 
 2. Bismuthinite 
 3'. Eucairite 
 
 4. Tellurium 
 
 5. Unknown (white), Bisbee 
 
 6. Lehrbachite 
 
 7. Berzelianite 
 
 8. Antimonial Bismuthinite 
 
 9. (Matildite) 
 
 2. HCL 
 
 1. Altaite 
 
 2. Clausthalite 
 
 3. Naumannite 
 
 2. SAME AS GALENA OR DARKER 
 
 1. HNO 3 NEG. 
 
 1. KOHNEG. 
 
 1. No EFF. AQ. REG. 
 
 1 . Jalpaite 
 
 2. Matildite 
 
 3. Unknown (Tonopah) 
 
52 MICROSCOPICAL DETERMINATION 
 
 2. EFF. AQ. REG. 
 
 1. Schirmerite 
 
 2. Rathite 
 
 3. Lengenbachite 
 
 4. Cinnabar 
 
 5. (Matildite) 
 
 6. (Polybasite) 
 
 7. (Bournonite) 
 2. KOH 
 
 1. Livingstonite 
 
 2. Stephanite 
 
 3. Sartor ite 
 
 4. Dufrenoysite 
 
 5. (Berthierite) 
 
 6. (Miargyrite) 
 2. HN0 8 
 
 1. KCNNEG. 
 
 1. HCLNEG. 
 
 1. FECLS NEC. 
 
 1. No EFF. HNO 3 
 
 1. Nagyagite 
 
 2. Freieslebenite 
 
 3. Guitermannite 
 
 4. Beegerite 
 
 5. Jordanite? 
 
 6. Andorite 
 
 7. Epiboulangerite 
 
 8. Unknown (near Andorite) 
 
 9. (Bismuthinite) 
 
 10. (Lengenbachite) 
 
 11. (Baumhauerite) 
 
 12. (Jamesonite) 
 
 2. EFF. HNO 3 
 
 1. Boulangerite 
 
 2. Dognacskaite 
 
 3. Horsfordite 
 
 4. Plagionite 
 
 5. (Chiviatite) 
 
 2. FECLS 
 
 1. Arsenic 
 
 2. "Alloklas" 
 
 3. Rezbanyite 
 
 4. Plenargyrite (hard) 
 
 5. Schapbachite (hard) 
 
 6. Petzite 
 2. HCL 
 
 1. FECLS NEG. 
 
 1. Geocronite 
 
 2. Meneghinite 
 
 3. Semseyite 
 
 4. (Zinkenite) 
 
 5. (Plagionite) 
 
 6. (Jamesonite) 
 
COLORI7 
 
 OF THE OPAQUE MINERALS 53 
 
 2. 
 
 1. Lillianite 
 
 2. Galena 
 
 3. Steinmannite 
 
 4. Tetradymite? 
 
 2. KCN .- 
 
 1. itermesite 
 2. Sti&iite 
 
 3. Hessite 
 
 4. (Guejarite) 
 
 5. (Brogniardite) 
 
 CREAMY WHITE 
 
 1. SAME AS SILVER, OR WHITER 
 1. FECLS NEG. 
 
 1. KOHNEG. 
 
 1. Matildite? 
 
 2. Guanajuatite 
 
 3. Chiviatite 
 
 4. (Bismuthinite) 
 
 5. (Galenobismutite) 
 
 2. KOH 
 
 1. Wittichenite 
 
 1. No EFF. AQ. REG. 
 
 1. Hessite? 
 
 2. Silver 
 
 3. (Altaite) 
 
 2. EFF. AQ. REG. 
 
 1. Huntilite 
 
 2. DARKER THAN SILVER 
 
 1. HNO 3 NEG. . 
 
 1. Unknown (creamy, Butte) 
 
 2. (Sulvanite) 
 
 3. (Chalmersite) 
 
 4. (Berthierite) 
 
 5. (Gold, var. electrum) 
 
 2. HNO 3 
 
 1. FECLs NEG. 
 
 1. Cosalite 
 
 2. Emplectite 
 
 3. Metacinnabarite 
 
 4. Sylvanite 
 
 5. (Frankeite) 
 
 6. (Wittichenite) 
 
 7. (Aikinite) 
 
 8. (Chiviatite) 
 
 9. (Freieslebenite) 
 
54 MICROSCOPICAL DETERMINATION 
 
 2. 
 
 1. HCLNEG. 
 
 1. Melonite 
 
 2. Calaverite (Krennerite) 
 
 3. Kalgoorlite 
 
 4. (Sylvanite) 
 
 5. (Arsenic) 
 
 6. (Hessite) 
 
 7. (Copper) 
 
 8. (Tapalpaite) 
 
 9. (Petzite) 
 
 2. HCL 
 
 1. Domeykite 
 
 2. Bismuth 
 
 3. Dyscrasite 
 
 4. Tapalpaite 
 
 5. Chilenite 
 
 6. (Teallite) 
 
 BLUISH WHITE. 
 
 1. HNO 3 NEG. 
 
 1. KOH NEC. 
 
 1. Tiemannite 
 
 2. Onofrite 
 
 3. Polyargyrite 
 
 4. Stiitzite 
 
 5. Unknown (Tonopah) 
 
 6. (Covellite) 
 
 7. (Kalgoorlite) 
 
 8. (Rathite) 
 
 9. (Cinnabar) 
 
 2. KOH 
 
 1. Proustite 
 
 2. Pyrargyrite 
 
 3. Unknown, bluish, with Sternbergite 
 
 4. Vrbaite 
 
 5. Miargyrite 
 
 6. (Stephanite) 
 
 2. HN0 3 
 
 1. KCNNEG. 
 
 1. Purple "galena" 
 
 2. Plenargyrite (" soft ") 
 
 3. Schapbachite ("soft") 
 
 4. (Coloradoite) 
 
 2. KCN 
 
 1. Cuprite 
 
 2. Stromeyerite 
 
 3. (Chalcocite) 
 
 4. (Polyargyrite) 
 
 5. (Brogniardite) 
 
WHITE/ COLORE 7 
 
 OF THE OPAQUE MINERALS 55 
 
 4. GRAYISH WHITE i i ^ 
 
 1. HNOaNEG. 
 
 1. KCNNEG. ' ;, : 
 
 1. Molybdenite 
 
 2. Regnolite 
 
 3. Seligmaunite 
 
 4. " Argentiferous Jamesonite " 
 
 5. (Cinnabar) 
 f5. (Kalgoorlite) 
 
 7. (Bournonite) 
 
 8. (Tiemannite) 
 
 9. (Rathite) 
 
 10. (Lengenbachite) 
 
 2. KCN 
 
 1. Orpiment 
 
 2. Argyrodite 
 
 3. Polybasite 
 
 4. Pearceite 
 
 5. (Jalpaite) 
 
 6. (Miargyrite) 
 
 7. (Stephanite) 
 
 8. (Livingstonite) 
 
 2. HN0 3 
 
 1. FECL 3 NEG. 
 
 1. HCL NEG. 
 
 1. Stannite 
 
 2. Baumhauerite 
 
 3. Realgar 
 
 4. Crookesite 
 
 5. (Freieslebenite) 
 
 6. (Guanajuatite) 
 
 7. (Andorite) 
 
 8. (Unknown near Andorite) 
 
 2. FUMES HCL 
 
 1. Cylindrite 
 
 2. Frankeite 
 
 3. Brogniardite 
 
 4. Jamesonite 
 
 5. Zinkenite 
 
 3. HCL 
 
 ' 1. (Alabandite) 
 2. (Cosalite) 
 
 2. 
 
 1. KCN NEG. 
 
 1. Teallite 
 
 2. Aguilarite 
 
 3. Petzite? 
 
 4. Coloradoite 
 
56 MICROSCOPICAL DETERMINATION 
 
 2. KCN 
 
 1. Chalcocite 
 
 2. "Tapalpaite" (gray) 
 
 -3. (Unknown, Qrayish, Butte, N 13) 
 
 4. Argentite 
 
 5. (Stromeyerite) 
 
 6. (Pearceite) 
 
 3. GRAY 
 
 1. HARDNESS HIGH 
 
 1. HCL CONC. NEG. 
 
 1. AQ. REG. NEG. 
 
 1. Cassiterite 
 
 2. Limonite 
 
 3. Chromite 
 
 4. (Rutile) 
 
 5. (Franklinite) 
 
 6. (Hematite) 
 
 7. (Ilmenite) 
 
 2. AQ. REG. 
 
 1. Uraninite 
 
 2. HCL CONC. 
 
 1. Franklinite 
 
 2. Psilomelane 
 
 3. (Magnetite) 
 
 2. HARDNESS MEDIUM 
 
 1. HCL NEG. 
 
 1. Sphalerite 
 
 2. Wurtzite 
 
 3. Voltzite 
 
 4. Erythrozincite 
 
 5. (Uraninite) 
 
 6. (Argyrodite) 
 
 2. HCL 
 
 1. Cuprodescloizite 
 
 2. (Cuprite) 
 
 3. (Alabandite) 
 
 4. (Tenorite) 
 
 5. (Delafossite) 
 
 3. HARDNESS Low 
 
 1. Lorandite 
 
 2. (Stannite) 
 
 3. ("Petzite?") 
 
 4. (Argyrodite) 
 
 5. (Erythrozincite) 
 
 6. (" Tapalpaite " gray) 
 
COLORED 
 
 TABLES FOR MINERAL IDENTIFICATION 
 
 57 
 
COLORED 
 BLUB 
 
 Bright 
 
 COVELLITE CuS 
 
 COL. Blue. Varies from deep bright blue, sometimes purple, to very 
 pale blue, almost white, like chalcocite. 
 
 Occ. Usually in minute plates appearing as needles in section, some- 
 times even feathery aggregates. Rarely in large plates, up to two 
 inches across. 
 
 HARD. Low. SURF. Smooth.' H. 1.5-2 j > rnite 
 
 CHEM. 1. HNOs . 2. HNOs cone. . 3. KCN. Instantly deep 
 
 violet, rapidly darker; rubs off, leaving a yellowish coating and 
 rough surface. 4. HC1 . 5. HC1 cone. . 6. Aq. Reg. In- 
 stantly effervesces a short time, then stops; turns pinkish where 
 
 bubbles started; rubs clean easily. 7. FeCls . 8. KOH . 9. 
 
 NaOH . 10. (NH 4 )2S X . 11. AgNO 3 3 per cent . Quickly 
 
 plated with silver, persistent. 12. K 4 Fe(CN) 8 . 13. Iodine . 
 
 14. KaFe(CN).. Slowly greenish, persistent. 15. NH 4 OH . 
 
 DIFF. Col. Chem. 1. 
 
 NOTE. Covellite, observed in plane polarized light, is pleochroic, 
 dark blue (parallel to the plane of vibration of the nicol) , to light 
 blue (perpendicular to this). Sections which appear dark blue 
 in ordinary light do not change color in polarized light. 
 
 CHALCOCITE See page 107. 
 
 58 
 
WHIT 
 
 Pale 
 
 See WHITE. HARDNESS Low. BLUISH WHITE, pp. 114-117. 
 
 Many pale blue minerals are transparent red with oblique illumination, 
 
 9 
 
 
 
 i 
 
 I 
 
 o 
 
 a 
 
 59 
 
 < 
 
 tu 
 ^ 
 u 
 
COLORED 
 PURPLE 
 
 Bright 
 
 UMANGITE CtuSej 
 
 COL. Bright reddish purple, very close to Rickardite. 
 
 HARD. Low. SURF. Smooth. H. 3. 
 
 CHEM. 1. HNO 3 . Turns bluish, persistent. 2. KCN . 3. HC1. 
 
 Turns bluish, persistent. 4. Aq. Reg. Turns a little bluish; rubs 
 
 to original color. 5. FeCls. Turns bluish, persistent. 6. KOH. 
 
 Slowly coated with brown; rubs easily to bluish. 7. (NH 4 )2S X . 
 
 Turns bluish; rubs to light blue. 
 DIFF. Col. Chem. 1. 
 
 RICKARDITE Cu 4 Tes 
 
 COL. Bright reddish purple, almost red, slightly brighter than umang- 
 ite. Microscopically mottled, with bluish and yellowish patches 
 mixed. 
 
 HARD. Low. SURF. Smooth. H. 3.5. 
 
 CHEM. 1. HNOs. Instantly effervesces and blackens. 2. KCN. 
 Faintly bluish. 
 
 DIFF. Col. Chem. 1. 
 
 PURPLISH BROWN " BORNITE " See page 65. 
 
 60 
 
WHITE/ 
 
 Pale 
 
 PURPLE " GALENA See page 116. 
 
 COLORADOITE See page 106. 
 
 
 
COLORED 
 YELLOW 
 
 Bright 
 
 CHALCOPYRITE CuFeSa 
 
 COL. Bright brass yellow. Sometimes appears pale, by association 
 
 with colored minerals. 
 
 HARD. Medium. SURF. Smooth. H. 3.5-4 = bn. 
 
 CHEM. 1. HNps . 2. HNO 3 . Hot. Tarnishes the mineral bright 
 
 colors, then dissolves it. 3. HNO 3 cone. Turns deep yellow; rubs 
 
 off. 4. KCN (but occasionally develops structure). 5. HC1 . 
 
 6. HC1 cone. . 7. HC1. Hot, same as hot HNO 3 . 8. Aq. Reg. 
 
 Tarnished iridescent. 9. FeCls . 10. KOH . 11. NaOH . 
 
 12. (NH 4 ) 2 Sx . 13. K 4 Fe(CN) 6 . 14. KsFe(CN) 6 . 15. 
 
 Iodine . 
 
 DIFF. Col. Surf. Chem. 4. 
 
 GOLD Au 
 
 COL. Golden yellow, richer than chalcopyrite, and usually deeper. 
 HARD. Low. SURF. Smooth, metallic. H. 2.5-3. 
 
 CHEM. 1. HNO 3 . 2. HNO 3 cone. . 3. KCN. Quickly 
 
 darkens and produces rough surface; sometimes develops structure. 
 
 4. HC1 . 5. HC1 cone. . 6. Aq. Reg. . 7. FeCl 3 . A little 
 
 pale and tarnished (?) ; rubs off very easily. 8. KOH . 9. 
 
 NaOH . 10. (NHOaSx . 11. K 4 Fe(CN) 6 . 12. KsFe(CN) 
 
 . 13. Iodine . 
 
 DIFF. Col. Surf. Chem. 3. 
 
 NOTE. Gold is variable in color, according as it is alloyed with 
 silver. Electrum is very pale yellow. A very good test for 
 small pieces of gold is to amalgamate by rubbing on a mercury 
 covered chamois skin. The gold will turn bright white. (F. C. 
 Lincoln devised this test.) 
 
 YELLOWISH AND ORANGE " BORNITES " See page 64. 
 
 62 
 
 
WHITER 
 
 Pale 
 
 HNOtNeQ 
 
 m 
 
 MILLERITE NiS 
 
 COL. Very pale yellow. 
 
 HARD. Medium. SURF. Smooth. H. 3-3.5 <po. 
 
 CHEM. 1. HNOa . 2. HNO 3 cone. Quickly bright yellowish 
 
 brown; rubs off easily to very pale. 3. KCN . 4. HC1 . 5. 
 
 HC1 cone. . 6. Aq. Reg. Slowly bright brown; fumes tarnish 
 
 brown; rubs clean easily. 7. FeCla . 8. KOH . 9. NaOH . 
 
 10. (NH 4 ) 2 S X . 11. K 4 Fe(CN) . 12. KaFeCCN), . 13. 
 
 Iodine . 
 
 DIFF. Col. Chem. 2, 6. 
 
 PYRRHOTITE See page 76. 
 SULVANITE See page 72. 
 CHALMERSITE See page 72. 
 GOLD (var. electrwri) See page 62. 
 
 o 
 tt 
 
 HNOi 
 
 MARCASITE See page 78. 
 PYRITE See page 78. 
 BISMUTH See page 125. 
 
 63 
 
 EC 
 
 C* 
 
 u 
 
COLORED 
 BBOWN 
 
 HNOs Neg. 
 
 UNKNOWN MINERAL " Orange Bornite " 
 
 A group of unknown minerals, ranging in color from orange yellow to 
 bright yellowish brown, occurring in small bits in bornite ores. Ap- 
 parently not affected by HNOs, but all reactions obscured by pres- 
 ence of easily soluble bornite. Usually resistant to enriching 
 solutions. 
 
 PYRRHOTITE See page 76. 
 KALGOORLITE See page 124 
 
 64 
 
WHITER 
 
 HNO, 
 
 UNKNOWN MINERAL Ejirplish brown " Bornite " 
 
 COL. Purplish brown. With bornite, distinctly purplish. 
 
 HARD. Low. SURF. Smooth. H = bn? 
 
 CHEM. 1. HNOs. Dissolves readily with effervescence, leaving rough 
 
 surface, pale gray or pinkish (more vigorous than ordinary bn). 
 DIFF. Col. Chem. 1. 
 
 NOTE. May be argentiferous bornite, as it occurs with silver 
 minerals and native silver in the two specimens studied. 
 
 STERNBERGITE-FRIESEITE Ag 2 Fe 6 S 8 or AgFe 2 S 3 
 
 COL. Pale yellowish brown. With bornite, pale yellowish brown, no 
 
 pink. 
 
 HARD. Low. SURF. Smooth. H. 1-1.5. 
 
 CHEM. 1. HNOs. Quickly bright iridescent; rubs to persistent gray. 
 
 2. KCN . 3. HC1 . 4. Aq. Reg. Faint brown. 5. FeCh . 
 
 6. KOH Quickly bright brown, rubs off. 
 DIFF. Col. Chem. 1, 2. - 
 
 BORNITE Cu 5 FeS 4 
 
 COL. Pinkish brown. 
 
 HARD. Low. SURF. Smooth. H. 3 < cp. 
 
 CHEM. 1. HNOs. Quickly golden brown, with effervescence, occasion- 
 ally developing "cleavage." 2. HNOs cone. Effervesces, tarnishes 
 bright reddish brown, which rubs off, showing fine-grained "cleav- 
 age." 3. KCN. Quickly brown, developing "cleavage, "like HNOa. 
 
 A more dilute sol. (3 per cent) produces coarser etching. 4. KC1 . 
 
 5. HC1 cone. 6. Aq. Reg. Instantly effervesces and etches 
 
 slightly ; turns pale yellowish brown ; fumes tarnish dark brown and 
 
 iridescent. 7. FeCls . Boiled with 5 per cent sol. a few minutes, 
 
 etches better than KCN. 8. KOH . 9. NaOH . 10. (NH 4 ) 2 S X . 
 
 Quickly blue and iridescent, rubs off easily. 11. H 2 SO 4 cone. . 
 
 12. NH 4 OH . 13. KsFe (CN) 6 . Very bright, uniform brown, 
 
 rubs off fairly easily. 14. K 4 Fe(CN) 6 + HC1 cone. Brilliant iri- 
 descent, persistent. 15. Iodine. Dissolves slightly. 
 
 DIFF. Col. Chem. 1. 
 
 NOTE. Color varies very slightly, from yellower to pinker brown. 
 
 UNKNOWN MINERAL (Brown, from Bisbee) 
 
 COL. Pale coffee brown. With bornite, pale grayish, yellowish, 
 brown, no red; with stern bergite, faintly grayer brown, very close; 
 with "orange bornite" slightly creamier brown, no red. 
 
 HARD. Medium or low. SURF. Smooth. H > bn. = cp. 
 
 CHEM. 1. HNOs. Rather quickly tarnished slightly darker brown; 
 
 rubs off easily. 2. KCN . 3. HC1 . 4. Aq. Reg. (or 
 
 slowly tarnished, with slight effervescence. Reaction may be modi- 
 fied by the presence of bornite). 5. FeCls . 6. KOH . 
 
 DIFF. Col. Chem. 1, 2. 
 
 BRONZE ENARGITE See page 74. 
 
 65 
 
COLORED 
 
 PINK 
 
 HNOi 
 
 KCN Neg. 
 
 NICCOLITE NiAs 
 
 COL. Creamy pink. With galena, distinctly pinkish cream; with 
 maucherite, pale, decidedly yellowish brown; with copper, pale 
 yellowish brown; with whitneyite, deep pinkish cream. 
 
 HARD. High. SURF. Shiny, pitted. H. 5-5.5. 
 
 CHEM. 1. HNOs. Instantly effervesces, darkens and etches. Coated 
 with white flocculent precipitate. Rubs off clean to show etched 
 
 surface. 2. KCN . 3. HC1 . 4. HC1 cone. . 5. Aq. Reg. 
 
 Slowly brown, with moderate effervescence. 6. FeCls . 7. 
 
 KOH . 8. NaOH . 9. (NHOS X . 10. NH 4 OH . 11. 
 
 K3Fe(CN) 6 . 12. K4Fe (CN) . 13. Iodine . 
 
 DIFF. Col. Chem. 1, 6. 
 
 NOTE. Niccolite with Sb shows intergrown breithauptite, or some 
 other mineral, and does not appear to grade chemically into breit- 
 hauptite. 
 
 BREITHAUPTITE NiSb 
 
 COL. Pink. With copper, very pale pink, no yellow tinge; with 
 niccolite, pink, with no yellow tinge. 
 
 HARD. Medium. SURF. Smooth. H. 5.5 niccolite. 
 
 CHEM. 1. HNOa. Quickly blackens and tarnishes; black persistent. 
 2. KCN . 3. HC1 . 4. HC1 cone- . 5. Aq. Reg. In- 
 stantly effervesces, slowly turns brown and etches; rubs to per- 
 sistent brilliant iridescent. 6. FeCla. Rapidly darkens; rubs clean, 
 
 showing pitted surface. 7. KOH . 8. (NH 4 ) 2 S X . 9. NH 4 OH 
 
 . 10. Iodine . 11. KsFeCCN). . 12. K4Fc(CN) 6 . 
 
 DIFF. Col. Chem. 6. 
 
 MAUCHERITE See page 79. 
 BISMUTH See page 125. 
 
 I 
 
 66 
 
WHITE/ 
 
 KCN 
 
 COPPER Cu 
 
 COL. Pink." With bornite, bright pink; with breithauptite, de- 
 cidedly yellowish pink. 
 
 HARD. Medium. SURF. Metallic, smooth. H. 2.5-3 > cc. 
 
 CHEM. 1 . HNOs. Dissolves rapidly, but merely roughens, and does not 
 change color. 2. HNOs cone. Instantly dissolves, tarnishes bright 
 iridescent, shows crystal (?) structure. Fumes tarnish iridescent, 
 persistent. 3. KCN. Slowly tarnishes brown; rubs off to show 
 
 very fine-grained solution surface. 4. HC1 . 5. HC1 cone. 
 
 Tarnishes slightly. 6. Aq. Reg. Blackens rapidly ; rubs black and 
 smooth. 7. Feds. Instantly blackens and makes a solution pit. On 
 washing off, the dilute solution tarnishes copper brilliant red, which 
 rubs off. 8. KOH. Slowly tarnished bright brown, then red, then 
 bright blue, persistent. 9. (NH^Sx. Instantly blackens, persistent. 
 Fumes tarnish brilliant. 10. NaOH. Turns light reddish brown, 
 persistent. 11. Iodine. Makes white coating, which rubs off very 
 easily, showing roughened surface below. 
 
 DIFF. Col. Surf. 
 
 BORNITE See page 65. 
 ALGODONITE See page 74. 
 WHITNEYITE See page 75. 
 COBALTITE See page 86. 
 FAMATINITE See page 99. 
 
 UJ 
 
 u 
 u 
 
COLORED 
 PINK 
 HN0 3 NBQ. 
 
 I 
 I 
 
 LUZONITE See page 98. 
 
 UNKNOWN PINKISH MINERAL (in Mohawkite) See page 76. 
 
WHITER 
 
 I 
 
 
 ot 
 u 
 
COLORED 
 CREAM 
 HARDNESS Low 
 
 See WHITE. HARDNESS Low. CREAMY WHITE, pp. 118-127. 
 
 70 
 
WHITER 
 
 
 
 * 
 
 cu 
 
 u 
 u 
 
COLORED 
 CREAM 
 
 HARDNESS MEDIUM 
 HNO 3 NEG. 
 
 SULVANITE CuaVS* 
 
 COL. Cream. With galena, very pale lemon yellow, almost cream; 
 
 with silver, pale yellowish cream. 
 
 HARD. Medium. SURF. Smooth. H. 3.5. 
 CHEM. 1. HNOs . Fumes tarnish ; rubs clean easily. 2. KCN . 
 
 3. HC1 . 4. Aq. Reg. Tarnishes bright brown, rubs clean easily. 
 
 5. FeCla . 6. KOH . 
 
 DlFF. Col. 
 
 CHALMERSITE CuFe 2 S 8 
 
 COL. Cream. With galena, decidedly cream colored; with chal- 
 
 copyrite, pale cream; with calaverite, decidedly yellower. 
 HARD. Medium. SURF. Smooth. H. 3.5 > cp. 
 
 CHEM. 1. HNO 3 . Fumes tarnish slightly. 2. KCN . 3. 
 
 HC1 . 4. Aq. Reg. Effervesces slightly; instantly bright iri- 
 descent, rubs clean easily. 5. FeCla . 6. KOH . 
 
 5? DIFF. Col. 
 
 M 
 
 !5J MILLERITE See page 63. 
 
 C/} UNKNOWN CREAMY MINERAL (Butte, N 13) See page 126. 
 
 
 
 Q PYRRHOTITE See page 76. 
 
 or 
 
 3 DELAFOSSITE See page 92. 
 
 S 
 
 a 
 
 5 
 
 72 
 
WHITE 
 
 
 
 2 
 O 
 
 
 
 2 
 
 E 
 
 73 
 
I 
 
 COLORED 
 
 CREAM 
 
 HARDNESS MEDIUM 
 
 HNO 
 
 BRONZE ENARGITE (CuSn), (SbAs), S ? 
 
 COL. Cream. With pyrrhotite, same; with galena, pale brownish 
 
 cream; with silver, pale brownish cream. 
 
 HARD. Medium. SURF. Shiny. H. = en. 
 
 CHEM. 1. HNOs. Very slowly bright brown. 2. HNOs cone. Rather 
 
 quickly brown, gradually turning brighter and iridescent. Rubs 
 
 easily to very faint brown, often showing a little structure (?). 3. 
 
 KCN. Solution slowly turns purplish red, increasing in intensity. 
 
 Mineral is slightly etched, but does not develop structure. 4. 
 
 HC1 - . 5. HC1 cone. - . 6. Aq. Reg. Quickly bright brown 
 
 iridescent; rubs clean easily. 7. FeCls - . 8. KOH - . 9. 
 
 NaOH - . 10. NH 4 OH - . 11. Iodine - . 12. K 4 Fe(CN) 6 - . 
 
 13. KsFe (CN) 6 - . 
 DIFF. Chem. 3. 
 
 NOTE. Contains Cu, Sn, Sb, As, S. Probably analogous to 
 enargite in composition, but with different crystal form. 
 
 ALGODONITE (CREAM) Cu,As (?) 
 
 COL. Cream. With galena, pale pinkish cream; with whitneyite, 
 pale cream; with mohawkite (cream), same. 
 
 HARD. Medium. SURF. Smooth. H. 4. 
 
 CHEM. 1. HNOs. Instantly blackens with effervescence, leaving a 
 rough surface. 2. KCN. Slowly brown, with slight effervescence. 
 Rubs to pale gray and shows structure. 3. HC1 - . 4. Aq. Reg. 
 Effervesces slightly and darkens and etches. 5. FeCls. Instantly 
 blackens. 6. KOH. Rapidly iridescent. 7. (NH 4 ) 2 S X . Instantly 
 bright iridescent. 8. Iodine. Turns gray. 9. NH 4 OH. Slowly pale, 
 even, brown. 10. K 4 Fe(CN) 6 . Tarnished gray, rubs off. 11. 
 K3Fe(CN) 6 . Faint brown, rubs off. 
 
 DIFF. Chem. 3, 6. 
 
 MOHAWKITE (CREAM) CusAs (with Ni and Co) 
 
 COL. Cream. With galena, pale pinkish cream; with algodonite 
 (cream), same. 
 
 HARD. Medium. SURF. Smooth. H. 4. 
 
 CHEM. 1. HNOs. At once black, with violent effervescence. 2. KCN. 
 
 Dissolved and turned brown; rubs off pale. 3. HC1 (when with 
 
 an unknown, harder mineral, blackens). 4. HC1 cone. Same as 
 3. 5. Aq. Reg. Same as 3. 6. FeCls. Instantly blackens, develops 
 
 structure (?) 7. KOH . 8. (NH 4 ) 2 S X . Instantly yellow. 9. 
 
 KsFe(CN)e. Slowly brilliant persistent tarnish; dissolves visibly. 
 10. K4Fe(CN)e. Slowly faint tarnish, forming persistent ring. 11. 
 Iodine. Turns bluish gray. 
 
 DIFF. Col. Chem. 3, 7. 
 
 NOTE. May be about the same as algodonite cream. 
 
 WHITNEYITE CuAs 
 
 COL. Cream. With galena, rather deep pinkish cream ; with maucher- 
 ite, pale brownish cream; with niccolite, cream; with copper, very 
 pale yellowish brown. 
 
 HARD. Medium. SURF. Smooth, but apt to be finely pitted. H. 3.5. 
 
 CHEM. 1. HNOs. Effervesces violently, and rapidly turns bright brown. 
 Dissolved. 2. KCN. Quickly dark brown; rubs to gray, showing 
 structure. 3. HC1. Tarnishes instantly; rubs clean. 4. Aq. Reg. 
 Instantly blackens and dissolves; develops structure. 5. FeCls. 
 Instantly blackens; rubs to dark gray. 6. KOH. Tarnishes quickly 
 bright yellow, then brown. 7. NH 4 OH. Slowly deep yellowish brown, 
 rubs to very faint purplish tinge. 8. (NH 4 )2S X . Instantly iridescent ; 
 rubs to dark gray. 9. KsFe(CN)g. Instantly brown; rubs clean very 
 easily. 10. K 4 Fe(CN). Faint brown, rubs clean. 11. Iodine, dark 
 gray iridescent. 
 
 DIFF. Col. Chem. 3, 6. 
 
WHITE 
 
 PENTLANDITE See page 100. 
 AIKINITE See page 10 l v 
 NICCOLITE See page 66. 
 LINN-EITE See page 79. 
 COPPER See page 67. 
 HAUCHECORNITE See page 79. 
 
 6 
 
 z 
 
 K 
 
 75 < 
 
 m 
 
 & 
 o 
 
COLORED 
 CREAM 
 
 HARDNESS HIGH 
 HNO 3 NEQ. 
 
 
 PYRRHOTITE FeS(S) x 
 
 COL. Cream. With galena, very pale brown; with silver, very pale 
 brownish cream; with arsenopyrite, very pale creamy brown. 
 
 HARD. High. SURF. Shiny but pitted. H. 3.5-4.5 ; cp. 
 
 CHEM. 1. HNOs - . Slowly very faint brown. Fumes tarnish 
 slightly. 2. HNO 3 cone. - ? 3. KCN - . 4. HC1 - . Fumes 
 quickly tarnish. 5. HC1 cone. - . 6. Aq. Reg. Effervesces slowly, 
 turns quickly brilliant iridescent in centre of drop, and brown near 
 edges. Fumes instantly tarnish brown. Rubs off easily to pale 
 brown. 7. FeCls - . 8. KOH. Slowly tarnishes brilliant irides- 
 cent colors, persistent. 9. NaOH, same as KOH. 10. (NH^zSx - . 
 11. K 4 Fe(CN) 6 - . 12. K3Fe(CN) 8 - . 13. Iodine -- . 14. Hot 
 HC1 tarnishes quickly bright colors, different on different grains, 
 then blackens and dissolves. 
 
 DIFF. Col. Chem. 6 and 14. 
 
 NOTE. Practically constant in color, though variable in sulphur 
 content. 
 
 UNKNOWN MINERAL (pinkish, in Mohawkite) ? 
 
 COL. Pale pinkish cream. With galena, very pale brown or cream, 
 
 with a tinge of pink; with maucherite, about same color. 
 HARD. High. SURF. Shiny, pitted. H. > mohawkite. 
 
 CHEM. 1. HNOs . Fumes tarnish slightly. 2. KCN . 3. 
 
 HC1 . 4. HC1 cone. . 5. Aq. Reg. . 6. FeCla . 7. 
 
 KOH . 
 
 DIFF. Col. Chem. 6. 
 
 NOTE. Some of the apparent inertness of this mineral may be 
 due to the fact that it occurs surrounded by the readily attacked 
 mohawkite, which may obscure or retard any reaction. Its 
 presence certainly affects some of the reactions of the mohawk- 
 ite. 
 The mineral may carry much Ni or Co, but this cannot be proved. 
 
 s 
 
 C/) 
 
 I 
 
 1 
 
WHITE 
 
 o 
 
 z 
 
 E 
 
 
 
 z 
 
 B 
 
 77 
 
 < 
 
 UJ 
 ^ 
 
 
s 
 
 J^< COLORED 
 
 Hj CREAM 
 
 HARDNESS HIGH 
 f/i HNO 3 
 
 Surface Dull 
 
 
 s 
 
 I 
 
 i 
 
 PYRITE FeSj 
 
 COL. Cream. With galena, pale creamy yellow; with arsenopyrite, 
 
 pale yellow. 
 Occ. Rounded or irregular grains, or in crystals, practically always 
 
 the oldest sulphide present. 
 
 HARD. High. SURF. Scratched and dull. H. 6-6.5. 
 
 CHEM. 1. HNO 3 . Slowly faint brown, with very slow effervescence. 
 
 Persistent. 2. HNO 3 cone. Same. 3. KCN - . 4. HC1 - . 5. 
 
 HC1 cone. - . 6. Aq. Reg. - . 7. FeCls - . 8. KOH - . 9. 
 
 NaOH - 10. K 4 Fe(CN) 6 -- . 11. K 3 Fe(CN) 8 - . 12. Io- 
 
 dine - . 13. (NH^Sx. Slightly tarnished ordinarily, but with 
 
 enargite, rather brightly tarnished. 
 DIFF. Hard. Occ. Col. Chem. 1. 
 
 MARCASITE FeSa 
 
 COL. Cream. With galena, pale creamy yellow; with silver, creamy 
 white; with arsenopyrite, decidedly yellowish; with pyrite, slightly 
 paler (usually) ; with millerite, paler and browner. 
 
 Occ. Frequently in radial growths, or intergrown with pyrite. 
 
 HARD. High. SURF. Scratched and dull. H. 6-6.5 = pyrite. 
 
 CHEM. 1. HNOs. Slowly effervesces, and turns brown to black, slowly; 
 persistent. 2. HNO 3 cone. Same. 3. KCN - . 4. HC1 - . 5. 
 HC1 cone. -- . 6. Aq. Reg. Very slowly faint brown, persistent. 
 7. FeCl 3 - . 8. KOH - . 
 
 DIFF. Col, Chem. 1. 
 
 78 
 
WHITE 
 
 Surface Shiny 
 
 LINN^EITE COsS, 
 
 COL. White. With galena, pale pinkish creamy white; with silver, 
 
 very pale brownish cream; with arsenopyrite, very pale pinkish 
 
 cream. 
 
 HARD. High. SURF. Shiny but usually pitted. H. 5.5 ; cp. 
 
 CHEM. 1. HNOs. Very faintly brownish; fumes slowly tarnish brown. 
 
 2. KCN - . 3. HC1 - . 4. HC1 cone. Slowly very faint brown. 
 
 5. Aq. Reg. - Fumes tarnish slightly. 6. FeCls - . 7. KOH - . 
 
 8. NH 4 OH -- . 
 DIFF. Col. Chem. 1. 
 
 MAUCHERITE Ni 3 As 2 
 
 COL. Cream. With galena, faintly pinkish cream; with silver, same 
 as with galena; with niccolite, very pale gray; with whitneyite, pale 
 grayish cream; with arsenopyrite, pale pink. 
 
 HARD. High. SURF. Shiny, pitted. H. 5. 
 
 CHEM. 1. HNOs. Effervesces vigorously, and blackens almost im- 
 mediately, rubbing clean to show roughened surface. 2. KCN . 
 
 3. HC1 . 4. HC1 cone. . 5. Aq. Reg. Slowly brown, with 
 
 moderate effervescence. 6. FeCls. Slowly faint brown, rather per- 
 sistent. 7. KOH . 8. (NH 4 ) 2 S X . 9. NH 4 OH . 10. 
 
 K 4 Fe(CN) 6 . 11. K 3 Fe(CN) 6 . Pale brown iridescent tarnish, 
 
 rubs off clean. 
 
 DIFF. Col. Chem. 1, 6. 
 
 HAUCHECORNITE (NiCo) 7 (Bi,S,Sb) 8 
 
 COL. Cream. With galena, rich cream color; with pyrrhotite 
 
 slightly less yellow, more of a pink tinge; polishes smoother, but is 
 
 very close; with millerite, purplish gray. 
 
 HARD. High-medium. SURF. Smooth. H. = 5 ? > millerite. 
 
 CHEM. 1. HNOs. Very slowly brown. Fumes tarnish slightly. Rubs 
 
 clean easily, leaving a slightly etched surface. 2. KCN . 3. 
 
 HC1 . Fumes tarnish slightly. 4. Aq. Reg. Quickly turns bright 
 
 brown, fumes tarnish slightly. Rubs clean very easily. 5. FeCls . 
 
 6. KOH . 
 
 DIFF. Chem, 4. 
 
 PENTLANDITE See page 100. Q 
 
 z 
 
 NICCOLITE See page 66. J3 
 
 79 
 
WHITE 
 
 HARDNESS HIGH 
 EFF. HNOi 
 AQ. REG. NEG. 
 
 ARGYROPYRITE See page 101. 
 MARCASITE See page 78 
 PYRITE See page 78. 
 
 ! 
 
 80 
 
WHITE 
 
 E 
 
 O 
 
 
 v) 
 
 s 
 
 i 
 
 i 
 
 5 
 
 o 
 
 ! 
 
 UJ 
 Q 
 
 81 
 
WHITB 
 
 HARDNESS HIGH 
 EFF. HNOi 
 AQ. REG. 
 
 FeCla Neg. 
 
 ARSENOPYRITE FeAsS 
 
 COL. White. With galena, pale cream; with silver, almost white, 
 slightly creamy; with chloanthite, pale yellowish white. 
 
 HARD. High. SURF. Scratched and dull usually. H. 5.5-6 < py? 
 
 CHEM. 1. HNOs. Quickly darkens (with effervescence) through iri- 
 descent colors to deep brown, with rough surface. 2. KCN . 3. 
 
 HC1 . 4. HC1 cone . 5. Aq. Reg. Slowly dark brown, with 
 
 slight effervescence. 6. FeCla . 7. KOH . 8. NH 4 OH . 
 
 DIFF. Col. Chem. 1, 6. 
 
 NOTE. Sometimes reaction 1 goes quite slowly. Gives off 
 arsenic odor when ground on coarse wheel. 
 
 KALLILITE NiBiS(Sb, As) 
 
 COL. White. With galena, very pale creamy white. 
 
 HARD. High (medium). SURF. Smooth. H. > cp. 
 
 CHEM. 1. HNOs. Quickly tarnishes iridescent. Effervesces slowly, 
 darkens. Coated with white, some parts more than others. 
 
 Rubs off to show gray, etched surface. 2. KCN . 3. HC1 . 
 
 4. Aq. Reg. Instantly effervesces, turns slowly brown, darker where 
 bubbles formed, and fumes tarnish brown instantly. Rubs clean, 
 showing etched surface. 5. FeCls . 6. KOH . 
 
 DIFF. Surf. Chem. 1, 4. 
 
 NOTE. Very like willyamite, but softer? 
 
 WILLYAMITE (CoNi)SbS 
 
 COL. White. With galena, pale creamy white. 
 
 HARD. High. SURF. Shiny, pitted. 
 
 CHEM. 1. HNOs. Instantly bright iridescent, then slowly dark brown. 
 Slight effervescence. Coated with white. Rubs to gray etched 
 surface. 2. KCN . 3. HC1 . 4. Aq. Reg. Instantly effer- 
 vesces, then slowly turns light brown, darker where bubbles formed. 
 Rubs clean easily, leaving practically no trace of etching. 5. 
 FeCls . 6. KOH . 
 
 DIFF. Surf. Chem. 1, 4. 
 
 NOTE. Very like kallilite, but harder? 
 
 POLYDYMITE Ni 4 S. 
 
 COL. White. With galena, pale creamy white; with arsenopyrite 
 practically pure white; with rammelsbergite, very pale pink. 
 
 HARD. High. SURF. Shiny but pitted. H. 4.5 > cp. 
 
 -^ CHEM. 1. HNOs. Slowly bright iridescent with slow effervescence. 
 
 JO Develops crystal structure. 2. KCN . 3. HC1 acid turns 
 
 i^ bright yellowish green. 4. HC1 cone. Same as HC1. 5. Aq. Reg. 
 
 V* Very slowly brown with slow effervescence. Acid turns greenish 
 
 *" yellow. Fumes tarnish slightly. 6. FeCls . 7. KOH . 8, 
 
 f . NH 4 OH . 
 
 U, DIFF. Chem. 1. 
 
 82 
 
SAFFLORITE CoAs 2 
 
 COL. White. With galena and silver, pure white; with arsenopyrite, 
 pure white; with smaltite, pure white. 
 
 HARD. High. SURF. Shiny but pitted. H. 4.5-5 < py. 
 
 CHEM. 1. HNOs. Effervesces and blackens quickly. Rubs clean to 
 show roughened surface. 2. KCN - . 3. HC1 - . 4. HC1 
 cone. - . 5. Aq. Reg. Slow effervescence, increasing in amount. 
 Mineral slowly turns faint brown, acid turns yellowish green. Rubs 
 off to very faint brownish stain. 6. Feds. Very slowly tarnishes 
 bright, and rubs off to show differential etching along crystal direc- 
 tions. 7. KOH - . 
 
 DIFF. Col. Chem. 6. 
 
 NOTE. Gives off arsenic odor when ground on coarse wheel. 
 
 SMALTITE CoAs 2 
 
 COL. White. With galena, pale creamy white; with arsenopyrite, 
 
 white; with safflorite, creamy white. 
 
 HARD. High. SURF. Shiny but pitted. H. 5.5-6 = Py. 
 
 CHEM. 1. HNOs. Instantly blackens with effervescence. Rubs to 
 
 persistent gray. 2. KCN-. 3. HC1 - . 4. HC1 cone. - . 5. 
 
 Aq. Reg. Effervescence begins very slowly and increases in rapidity. 
 
 Then mineral begins to turn brown rather quickly and develops 
 
 structure. Rubs off to show roughened gray surface, with structure 
 
 well brought out. 6. FeCls. Rapidly blackens, and shows etched 
 
 surface. 7. KOH - . 8. NH 4 OH - . 
 DIFF. Col. Chem. 6. 
 
 NOTE. Gives off arsenic odor when ground on coarse wheel. 
 
 SKUTTERUDITE ? CoAs 3 
 
 COL. White. With smaltite, practically the same (creamier?). 
 HARD. High. SURF. Shiny, pitted. H. = 6 
 
 CHEM. 1. HNOs. Quickly blackens with effervescence, showing a 
 white coating. Zonal structure developed by differential etching. 
 Rubs to very rough surface. 2. KCN - . 3. HC1 - . 4. Aq. Reg. 
 Effervesces quickly at first, then slowly and again increases. 
 Slowly turns brown. Etched differentially. Rubs clean. 5. FeCls. 
 Quickly brown, differentially, one part practically untouched. 6. 
 KOH - . 
 DIFF. Col. Chem. 1. 
 
 NOTE. May be smaltite, or smaltite may be skutterudite. Gives 
 off arsenic odor when ground on coarse wheel. , 
 
 MAUCHERITE See page 79. 
 
 r 
 
 2 
 
 03 
 
 tr 
 
 83 
 
WHITE 
 
 HARDNESS HIGH 
 No EFF. HNOs 
 HC1 UNCHANGED 
 Err. AQ. REG. 
 
 
 I 
 
 FeCls Neg. 
 
 LOLLINGITE FeAsi 
 
 COL. White. With galena, very faint creamy white; with silver, 
 practically pure white with a suggestion of pink; with arsenopyrite, 
 same as with silver. 
 
 HARD. High. SURF. Shiny but pitted. H. 5-5.5 = py. 
 
 CHEM. 1. HNOs. Very faintly brown, especially by fumes. 2. KCN 
 - . 3. HC1 - . 4. HC1 cone. - . 5. Aq. Reg. Slowly effervesces 
 and very slowly turns faint brown, easily rubbed clean. 6. FeCls - . 
 7. KOH - . 8. NaOH - . 9. (NH 4 )2S*. Slowly brown, dries 
 iridescent brown; rubs clean easily. 10. NH4OH - . 
 
 DIFF. Chem. I, 6. 
 
 NOTE. Gives off arsenic smell when ground on coarse wheel. 
 
 ULLMANITE NiSbS 
 
 COL. White. With galena, white with very faint creamy tint; with 
 arsenopyrite, practically pure white. 
 
 HARD. High. SURF. Shiny but pitted. H. 5.^6. 
 
 CHEM. 1. HNOs. Tarnishes quickly brown, then bright, repeating 
 with higher order colors; rubs to persistent iridescent gray. 2. KCN 
 - . 3. HC1 - . 4. HC1 cone. - . 5. Aq. Reg. Effervesces strongly 
 and blackens rapidly, effervescence stopping when black film forms. 
 Rubs to persistent dull gray. 6. FeCls - . 7. KOH - . 8. 
 NH 4 OH - . 
 
 DIFF. Chem, 1, 6. 
 
 ARSENOPYRITE See page 82. 
 
 i 
 
 84 
 

 E 
 O 
 
 X 
 M 
 
 1 
 
 4 c* 
 
 c < 
 
 CHLOANTHITE NiAs, jj C 
 
 COL. White. With arsenopyrite, pure white; with galena, faintly 
 
 creamy white; with silver, pure white; with rammelsbergite, same 
 
 color. >-> 
 
 HARD. High. SURF. Shiny but pitted. H. 5.5-6. ^ 
 
 CHEM. 1. HNOs. Rather quickly brown, with tarnish around edges of _H 
 
 drop; rubs to brownish gray, roughened surface. 2. KCN . 3. O 
 
 HC1 cone. . 4. Aq. Reg. Effervesces and slowly darkens. Rubs ^ 
 
 faint. 5. FeCls. Mineral practically unchanged, but solution turns K 
 
 dark yellowish brown. 6. KOH . s_ 
 
 DIFF. Chem. 4, 5. 
 
 NOTE. Gives off arsenic odor when ground on coarse wheel. 
 
 RAMMELSBERGITE NiAs, S 
 
 COL. White. With galena, pale creamy white; with silver, practi- < 
 
 cally pure white; with chlpanthite, same; with arsenopyrite, white. 
 
 HARD. High. SURF. Shiny but often pitted. H. 5.5-6. !^ 
 
 CHEM. 1. HNOs. Rather quickly brown, with tarnish around the UJ 
 
 edges. Shows a roughened surface. 2. KCN . 3. HC1 . Jg 
 
 4. HC1 cone. . 5. Aq. Reg. Effervesces slowly and solution turns 
 
 greenish yellow; shows roughened surface. 6. FeCla. Very slowly fa 
 
 faint brown, persistent. 7. KOH . 
 
 DIFF. Chem. 5, 6. 
 
 NOTE, Gives off arsenic odor when ground on coarse wheel. ^ 
 
 O 
 
 | 
 
 i * 
 
 ": i 
 
 CA 
 
 3 CA 
 
 W 
 
 Q Q 
 
 8 Sj 
 
 85 E 
 
WHITE 
 
 HARDNESS HIGH 
 No EFF. HNOj 
 HC1 UNCHANGED 
 No EFF. AQ. REG. 
 
 Aq. Reg. Neg. 
 
 I 
 
 COBALTITE CoAsS 
 
 COL. White. With galena, pale creamy brown; with silver, same as 
 with galena; with arsenopyrite, pale pinkish brown. 
 
 HARD. High. SURF. Scratched and dull. H. 5.5-6 = py. 
 
 CHEM. 1. HNOs. Very faintly browned, shows only after rubbing. 2. 
 
 HC1 . 3. HC1 cone. . 4. KCN. Slowly very pale brown, rubs 
 
 clean. 5.Aq.Reg. . 6.FeCl 3 . 7.KOH . 8.HN4OH . 
 
 DIFF. Col. Chem. 5. 
 
 LINN JEITE See page 79. 
 
 I 
 
 I 
 
 I 
 I 
 
 I 
 
 
 86 
 

 
 O 
 
 53 
 
 Aq. Reg. 
 
 GLAUCODOT (CoFe)AsS 
 
 COL. White. With galena, pale (brownish) creamy white; with 
 silver, very pale brownish white; with arsenopyrite, very pale pink- 
 ish white. (Observed on a crystal face, not an artificially polished 
 surface.) 
 
 HARD. High. SURF. Scratched and dull. H. 5. 
 
 CHEM. 1. HNOs. Readily turns dark gray, producing rough surface. 
 
 2. KCN . 3. HC1 . 4. HC1 cone. . 5. Aq. Reg. Very 
 
 slowly tarnished dark brownish gray, persistent. 6. FeCls . 7. 
 
 KOH . 8. Ammonium molybdate, 10 per cent . 
 
 DIFF. Col. Chem. 1, 5. 
 
 NOTE. Gives off arsenic odor when ground on coarse wheel. 
 
 PENTLANDITE See page 100. 
 
 i 
 
 I 
 
 U 
 
 E 
 
 u: 
 
 Q 
 
 
 
 a 
 
 LU 
 
 S 
 
 ca 
 
 I 
 
 a 
 
 87 
 
 s 
 
 ca 
 ca 
 
 UJ 
 
 Z 
 
 Q 
 U 
 < 
 E 
 
V 
 
 WHITE 
 
 HARDNESS HIGH 
 
 No EFF. HNO 3 
 
 HC1 TURNS YELLOWISH GREEN 
 
 GERSDORFFITE NiAsS 
 
 COL. White. With galena, faintly brownish creamy white; with 
 arsenopyrite, practically pure white. 
 
 HARD. High. SURF. Shiny, but rough. H. 5.5. 
 
 CHEM. 1. HNOs. Immediately tarnishes bright, then in a few seconds 
 
 blackens; rubs to gray roughened surface. 2. KCN . 3. HC1 
 
 acid turns bright yellowish green. 4. HC1 cone. Same as HC1. 
 5. Aq. Reg. Very slowly tarnishes brown, sometimes with efferves- 
 cence; persistent. 6. FeCls . 7. KOH . 8. NH^OH . 9. 
 
 Picric acid 10 per cent . 
 
 DIFF. Chem. 1, 5. 
 
 I 
 
 I 
 I 
 
 I 
 I 
 
I 
 
 Cfl 
 
 I 
 
 
 
 5 
 
 OJ 
 
 UJ 
 
 a 
 
 ^ 
 
 E 
 
 i! 
 
 S 
 
 H 
 
 s 
 
 LU 
 
 z 
 
 a 
 c* 
 
WHITE 
 
 HARDNESS HIGH 
 HNO 3 NEG. 
 
 HC1 Cone. Neg. 
 
 I" 
 
 ! RUTILE TiOa 
 
 COL. White. With galena, pale grayish white; with tetrahedrite, 
 very slightly grayer. Sometimes shows transparent red with oblique 
 light, and is then bluer by vertical illumination. 
 
 HARD. High. SURF. Shiny, pitted. H. 6-6.5. 
 
 CHEM. Not attacked by any reagents. 
 
 DIFF. Chem. Col. 
 
 NOTE. Very hard to polish free from pits. 
 
 ILMENITE FeTiOi 
 
 COL. White. With galena, pale grayish white; with sphalerite, dis- 
 
 tinctly whiter; with magnetite, pale purplish; with hematite, 
 
 distinct pale purplish gray; with tetrahedrite, slightly grayer. 
 
 HARD. High. SURF. Shiny, pitted. H. 4.5-5 > magnetite. 
 
 CHEM. 1. HNO 3 - . 2. KCN - . 3. HC1 cone. - . 4. HC1 cone. 
 
 hot - . 5. Aq. Reg. - . 
 DIFF. Col. Chem. 
 
 NOTE. Very hard to polish free from pits. Sometimes shows 
 slight variation in color. Frequently intergrown with magnetite. 
 
 HEMATITE Fe 2 O 3 
 
 COL. White. With galena, pale creamy grayish white; with magne- 
 
 tite, white; with tetrahedrite, lighter, bluish? white. 
 Occ. Often as plates (specularite) , and then easily recognized by form 
 
 and hardness alone. Sometimes massive, intergrown with magnetite. 
 HARD. High. SURF. Shiny, pitted. H. 5.5-6.5 = mg. 
 
 CHEM. 1. HNOs - . 2. KCN - . 3. HC1 - . 4. HC1 cone. - . 
 
 5. Aq. Reg. - . 6. FeCl 3 - . 7. KOH - . 8. HC1 cone, hot - . 
 
 9. HNO 3 hot - . 
 DIFF. Col. Occ. Chem. Hard. 
 
 NOTE. Very hard to polish free from pits. 
 
 PYRRHOTITE See page 76. 
 FRANKLINITE See page 144. 
 
 I 
 I 
 
 90 
 
HC1 Cone. 
 
 MAGNETITE Fe 3 O4 
 
 COL. White. With galena, very dull (purplish) grayish white; with 
 
 sphalerite, distinctly lighter, with suggestion of creamy; with hema- 
 tite, faint creamy brown; with ilmenite, lighter and creamy; with 
 
 tetrahedrite, very pale grayish brown. Sometimes has a purnlish 
 
 tarnish, persistent. 
 
 HARD. High. SURF. Shiny, pitted. H. 5.5-6.5 < ilmenite and hematite. 
 CHEM. 1. HNO 3 cone. . 2. KCN . 3. HC1 cone, slowly turna 
 
 brown, some grains faster than others. Acid turns yellow. 4 Aq. 
 
 Re f- Sam e as HclcoQ c. 5. HC1 cone. hot. Readily blackened 
 
 and dissolved. 
 DIFF. Col. Chem. 5. 
 
 NOTE. Very hard to polish free from pits. 
 
 SPERRYLITE PtAs 2 Jg 
 
 C L. White (not compared with any mineral, but appears white). 
 
 1 he specimens examined were not polished, but were minute crys- M 
 
 tals, mounted in sealing wax, and the reactions observed on the O 
 
 crystal faces. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 .^t^Hd cone* 5? 
 
 Very slowly faint yellow, washes off, leaving surface unchanged. 
 
 Yellow probably due to coloration of acid. Test doubtful. 5. Aq. t/\ 
 
 Keg. bame as HC1 cone, but slower. 6. FeCls . 7. KOH . 8 JJ? 
 
 KClOs and H 2 SO 4 cone. Quickly bright orange yellow, then darker' % i 
 
 to bright yellowish brown. Washes off to very pale brown, which fes 
 
 rubs off easily. 9.H 2 SO 4 conc. Slowly light brownish yellow, deep- Z 
 
 enmg gradually, easily washes off clean. Like KC1O 3 and H 2 SO< O 
 
 cone, but less vigorous. *-* 
 
 DITF. Chem. 8, 9. UZ 
 
 UNKNOWN PINKISH MINERAL (in Mohawkite) See page 76. 
 
 91 
 
WHITE 
 
 HARDNESS MEDIUM 
 GRAYISH WHITE 
 HNOs NEQ. 
 
 KCN Neg. 
 
 BOURNONITE (PbCu 2 ) 3 Sb 2 S6 
 
 COL. White. With galena, very pale grayish white, very nearly 
 same; with silver, dull grayish (bluish) white; with tetrahedrite, 
 grayish white, no brown. 
 HARD. Medium or low. SURF. Smooth. H. 2.5-3 < td. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 . 4. HC1 cone. . 
 
 5. Aq. Reg. Quickly blackens with effervescence, produces a coating 
 
 of free sulphur. 6. FeCls . 7. KOH . 8. NH 4 OH . 
 
 DIFF. Chem. 2, 5. 
 
 NOTE. Some bournonite is turned brown by HNOa, acid and 
 fumes, or by acid alone. Brighter along cracks in the mineral, 
 or around pyrite grains. 
 
 TENORITE CuO 
 
 COL. White. With galena, pale greenish gray, and darker greenish 
 gray (hard and soft portions); with tetrahedrite, hard part nearly 
 the same, and soft decidedly darker. The soft part is probably the 
 earthy form, melaconite. 
 
 Occ. Often crusted, like some limonite, with layers of varying hard- 
 ness; or in minute plates or crystals. 
 
 HARD. Medium. SURF. Smooth. H. 3-4. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1. Quickly darkens; drop 
 
 spreads out rapidly, forming and carrying with it a ring of pale green- 
 ish blue coating. Then acid rapidly evaporates, leaving a mass of 
 minute acicular, nearly colorless crystals on the surface. Fumes 
 tarnish brilliant iridescent. Fumes and coating wash off readily. 
 4. Aq. Reg. Same as HC1. 5. FeCls. Very slowly faint brown, rubs 
 clean easily. 6. KOH . 
 
 DIFF. Chem. 3. 
 
 DELAFOSSITE Cu, Fe, O 
 
 COL. Pale creamy gray. With galena, creamy gray; with sphalerite, 
 grayish cream; with tetrahedrite, slightly yellower and duller. 
 
 HARD. Medium. SURF. Smooth. H. 2.5 > copper. 
 
 CHEM. 1. HNOs . 2. KCN . 3. HC1. Darkens slightly and 
 
 rather rapidly dissolves, developing structure. Shows etched sur- 
 face clearly after rubbing. 4. Aq. Reg. Etches rather slowly and 
 
 slightly. Acid quickly turns yellowish green. 5. FeCls . 6. 
 
 KOH . 
 
 DIFF. Col. Chem. 3. 
 
 TETRAHEDRITE See page 94. 
 R REGNOLITE See page 104. 
 
 1 
 
KCN 
 
 
 
 z 
 
 8 
 
 POLYBASITE See page 105. 
 ENARGITE See page 95. 
 ARGYRODITE See page 105. 
 
 5 
 
 6 gj 
 
 2 S 
 
 C W 
 
 8 S3 
 
 S z 
 
 3 O 
 
 I* or 
 
 6 
 
 z 
 
 E 
 
WHITE 
 
 HARDNESS MEDIUM 
 GRAYISH WHITE 
 FUMES HNO 3 
 
 KCN Neg. 
 
 TETRAHEDRITE Cu8Sb 2 S 7 
 
 COL. Grayish white. With galena, dull pale gray with a suggestion 
 
 of brown. Slightly variable, grading towards tennantite in color. 
 HARD. Medium. SURF. Smooth. H. 3-4.5 = cp. 
 
 CHEM. 1. HNOa . Fumes tarnish slowly light brown, rubs off easily 
 
 (sometimes not affected even by fumes). 2. KCN (see note). 
 
 3. HC1 . 4. HC1 cone. . 5. Aq. Reg. Slowly effervesces, 
 
 acid turns greenish yellow; after a few minutes shows a coating of 
 sulphur, which can be rubbed off, leaving a pitted surface. 6. 
 
 FeCls . 7. KOH . 8. (NH 4 ) 2 S X . Slowly tarnished bright 
 
 brown, rubs off. 9. K 4 Fe(CN) 6 . 10. K3Fe(CN) 6 . 
 
 DIFF. Col. Chem. 1, 5 (grades towards tennantite in properties). 
 NOTE. Freibergite, the silver bearing tetrahedrite, is very close 
 
 to this, but is tarnished bright iridescent with HNOs. 
 Mercurial tetrahedrite is slightly bluer, and is slowly tarnished 
 bright iridescent with HNOs. KCN left on for about a minute 
 and a half turns ordinary tetrahedrite very faint brown, and 
 etches it slightly. 
 Gives a reddish streak on the canvas wheel. 
 
 TENNANTITE Cu 8 As 2 S 7 
 
 COL. Grayish white. With galena, dull grayish, with a suggestion of 
 green; with tetrahedrite, slightly bluer gray, grading towards the 
 same color. 
 HARD. Medium. SURF. Smooth. H. 3-4.5 = cp. 
 
 CHEM. 1. HNOs . Fumes tarnish bright brown, rubs off. 2. KCN 
 
 (see note). 3. HC1 . 4. HC1 cone. . 5. Aq. Reg. Slowly 
 
 effervesces, tarnishes bright iridescent in a few moments. Rubs off 
 
 to show a pitted surface. 6. FeCla . 7. KOH . 8. (NH 4 ) 2 S X . 
 
 Rather quickly bright brown. 9. K 3 Fe(CN) 6 . Slowly tarnished 
 
 brown, rubs off. 10. K 4 Fe(CN) 6 . 11. Iodine . 
 
 DIFF. Col. Chem. 1, 5 (grades towards tetrahedrite in properties). 
 NOTE. With KCN for 1^ minutes acts same as tetrahedrite. 
 Gives a reddish streak on the canvas wheel. 
 
 HAUERITE MnS 2 
 
 COL. Grayish white. With galena, pale gray or grayish white; with 
 
 tetrahedrite, slightly white, or more neutral, with no yellowish 
 
 tinge. Practically opaque. 
 
 HARD. Medium. SURF. Smooth. H. = 4. 
 CHEM. 1. HNO 3 . Fumes tarnish a little, very slowly. 2. KCN . 
 
 3. HC1 . 4. Aq. Reg. Slowly very faint brown. Fumes tarnish 
 
 faintly. Rubs clean easily, leaving a smooth surface. 5. FeCla . 
 
 6. KOH . 
 
 DIFF. Chem. 4. 
 
 NOTE. Gives an orange streak on the canvas wheel. 
 
 BOURNONITE See page 92. 
 
 
 l 
 
KCN 
 
 ENARGITE 
 
 COL. White. With galena, very dull grayish white, with a suggestion 
 of pinkish brown; with silver, very dull grayish white; with argen- 
 tite, dull pinkish gray; with tetrahedrite, decidedly pinkish gray. 
 HARD. Medium. SURF. Smooth. H. 3 = cp. 
 
 CHEM. 1. HNOs . Fumes slowly tarnish faint brown. 2. KCN. 
 
 Quickly blackens and etches. Rubs clean, showing etched surface 
 
 with structure or cleavage developed. 3. HC1 . 4. HC1 cone. . 
 
 5. Aq. Reg. Quickly brown, appears to roughen ; rubs clean easily. 
 
 Fumes tarnish slightly. 6. FeCl 3 . 7. KOH . 8. (NH 4 )2S X - 
 
 Slowly bright brown, iridescent; rubs clean easily. 9. KiFe(CN). 
 
 . 10. K 4 Fe(CN) 6 . 11. Iodine . 
 
 DIFF. Chem. 2, 5. 
 
 NOTE. Ordinary enargite, faintly pinkish, is here called white 
 enargite. This shows perfect cleavage, and may be wholly pure 
 Cu;iAsS4, or, as in some cases, may carry considerable antimony 
 without appreciably altering its physical or microchemical 
 
 properties. (Some antimonial enargite from Peru, however, is JJ 
 
 browned and etched by HNOa, while ordinary enargite is not.) 
 
 Massive white enargite, without cleavage, but in crystal ~ ^ 
 
 grains, as shown by etching, has been observed from Goldfield. Q UJ 
 
 This carries equal portions of antimony and arsenic. ^ 5 
 
 Pink enargite, which shows decidedly pink against ordinary X-i 
 
 enargite, has not been observed in crystals, except granular T t\ 
 
 aggregates, without good crystal form, and never shows cleav- 
 age. It carries apparently all proportions between practically 
 all arsenic and no antimony, to nearly all antimony and no 
 arsenic. The former corresponds to luzonite, and the latter to 
 famatinite. An intermediate member occurs in Goldfield, with 
 about equal amounts of antimony and arsenic. This has 
 slightly different microchemical properties from other pink 
 enargites. 
 
 A whiter form of famatinite, with cleavage, that is, the anti- 
 mony end-member of the normal enargite series, has not yet 
 been observed. 
 
 Enargite is frequently intergrown curiously with tennantite, 
 giving the former a mottled appearance. This is very common 
 at Butte, and has been called "mottled enargite" by L. C. 
 Graton and the writer. The enargite in this intergrowth is free 
 from antimony, and also varies perceptibly in degree of pinkness. 
 
 o 
 
 Z c/) 
 
 8 m 
 
 Q 
 
 95 
 
fi 
 
 i 
 
 WHITE 
 
 HARDNESS MEDIUM 
 GRAYISH WHITE 
 HN0 3 
 
 KCN Neg. 
 
 ALGODONITE (GRAY) CuAs? 
 
 COL. Grayish white (part of a mixture). With galena, very pale 
 gray. 
 
 HARD. Medium. SURF. Smooth. H. 4? 
 
 CHEM. 1. HNOs. Instantly blackens, with effervescence, leaving a 
 
 rough surface. 2. KCN . 3. HC1 . 4. Aq. Reg. . 5. 
 
 FeCl 3 . 6. KOH. Turns yellowish brown. 7. (NHOzSx. In- 
 stantly bright iridescent. 8. Iodine . 9. K 4 Fe(CN) 6 . Blackened, 
 
 rubs clean. 10. KsFe(CN) G . Faint brown, rubs clean. 
 
 DIFF. Chem. I, 4. 
 
 POLYTELITE 4(PbAgFeZn)S-Sb 2 S 3 ? 
 
 COL. White. With galena, dull grayish white; with tetrahedrite, 
 
 slightly grayer? 
 
 HARD. Medium. SURF. Smooth. H.? = Td? 
 CHEM. 1. HNOs. Slowly bright brown and iridescent, persistent. 2. 
 KCN . 3. HC1 . 4. Aq. Reg. Instantly bright brown, effer- 
 vesces and blackens, persistent. 5. FeCls . 6. KOH . 
 
 DIFF. Chem. 1, 2. 
 
 NOTE. Distinguished from freibergite only by the absence of 
 copper. This is a very doubtful species. 
 
 ALABANDITE MnS 
 
 COL. Grayish white. With galena very pale dull gray; with silver, 
 pale bluish gray; with argentite, slightly darker. Transparent green 
 by oblique light. 
 
 HARD. Medium. SURF. Smooth. H. 3.5-4 = cp. 
 
 CHEM. 1. HNOs. Instantly effervesces and darkens; rubs to light gray 
 with little solution pits. If patch is large enough, odor of HsS is 
 
 evident. 2. HNO 3 cone. Same. 3. KCN . 4. HC1. Same as 
 
 HNO 3 . 5. HC1 cone. Same. 6. Aq. Reg. Dissolves readily with 
 
 evolution of H 2 S. Leaves a rather smooth solution pit. 7. FeCls . 
 
 8. KOH . 9. NaOH . 10. Iodine. Brilliant tarnish; rubs 
 
 off rather easily to faint. 11. (NH^Sx. Very slowly iridescent; 
 
 rubs clean easily. 12. NH 4 OH . 13. K 3 Fe(CN) 6 . Slowly faint 
 
 brown; rubs off easily. 14. K4Fe(CN)e. Same. 
 
 DIFF. Col Chem. 1, 6. 
 
 GEOCRONITE See page 132. 
 
 FREIBERGITE See page 94 (note under tetrahedrite). 
 
 BAUMHAUERITE See page 108. 
 
 MOHAWKITE (GRAY) See page 97. 
 
 CROOKESITE See page 109. 
 
 PLAGIONITE See page 135. 
 
 STYLOTYPITE See page 97. 
 
 BOURNONITE See page 92. 
 
 [2 
 
 ^ 96 
 
KCN 
 
 UNKNOWN MINERAL (QuATisH WHITE, Butte, N. 13) 
 
 COL. White. With galena, faint brownish grayish white; with silver, 
 
 decidedly grayish white; with tetrahedrite, about same, but less 
 
 yellowish, or brown (?). 
 
 HARD. Medium to low. SURF. Smooth. H. > bn < unknown 
 
 creamy, Butte, N 13. 
 CHEM. 1. HNOs. Instantly effervesces and turns gray, persistent. 
 
 Develops cracks, rubs off rough. 2. KCN. Instantly brilliant iri- 
 descent. Rubs easily to pale, persistent tarnish. 3. HC1 . 4. 
 
 Aq. Reg. Quickly darkens and roughens. Rubs fairly easily to 
 
 original color. 5. FeCl 3 . Rather quickly darkens, finally grayish 
 
 brown; develops cracks; rubs off easily. 6. KOH . 
 
 DIFF. Chem. 1, 2. 
 
 NOTE. Probably carries Bi. 
 
 MOHAWKITE (GRAY) Cu 3 As (with Ni and Co)? 
 
 COL. Grayish white. With galena, very pale (yellowish ?) gray; 
 
 with silver, same 'as with galena. Has needles of purplish color in it, *D 
 
 like those in domeykite. ** 
 
 HARD. Medium. SURF. Smooth. H. 4. Q 
 
 CHEM. 1. HNO 3 . Effervesces violently, turns purple, then black. 2. 
 
 KCN ? (with unknown pinkish mineral, is slowly etched). 3. M 
 
 HC1 (with unknown pinkish mineral is etched). 4. Aq. Reg. ^ 
 
 (with unknown pinkish mineral, is etched). 5. FeCls . 6. KOH. 
 
 Tarnishes bluish, rubs off, leaving purplish tinge. 7. NaOH. Tar- W) 
 
 nishes brown, then brilliant, persistent. 8. NH 4 OH. Blackens, then (/) 
 
 turns iridescent. 9. (NH^Sx. Instantly iridescent. 10. [Tj 
 
 K3Fe(CN) 6 . Slowly brilliant colors, very persistent. Forms solu- 5 
 
 tion pit. -* 
 
 DIFF. Occurrence as part of intergrowth. Chem. 6. Q 
 
 * 
 
 STYLOTYPITE (Cu 2 Ag 2 Fe) 3 Sb 2 Se? 
 
 COL. White. With galena, grayish white; with tetrahedrite, prac- 
 tically the same. 
 
 HARD. Medium. SURF. Smooth. H. 3 = cp. 
 
 CHEM. 1. HNO 3 . Very slowly brownish yellow and red. Some grains 
 
 hardly touched. Fumes tarnish slightly. Rubs clean easily. 2. 
 
 KCN. Turns faint gray? Rubs clean easily, leaving a slightly 
 
 roughened surface. (Test is not well established.) 3. HC1 . 4. 
 
 Aq. Reg. Slowly pale brown. After a while effervesces slightly. 
 
 Fumes tarnish a little. Rubs clean easily. 5. FeCls . 6. KOH. 
 
 Very slowly faint brown. Rubs easily to very faint brown, slightly 
 
 roughened surface. 
 DIFF. Chem. 1. 
 
 PLAGIONITE See page 135. 
 
 
 
 z 
 
 E 
 
 97 
 
WHITE 
 
 HARDNESS MEDIUM 
 
 PINKISH WHITE 
 
 HNO 3 Neg. 
 
 LUZONITE 
 
 COL. Pink. With galena and silver, pale pink; with enargite, dis- 
 tinctly pale pink. Color variable faint to decided pink. 
 
 HARD. Medium. SURF. Smooth. H. 3.5 = en. 
 
 CHEM. 1. HNO 3 . Fumes tarnish slightly. 2. KCN. Slowly 
 
 darkens and dissolves, like enargite, the darker pink more quickly 
 
 than the paler. 3. HC1 . 4. Aq. Reg. Quickly bright iridescent, 
 
 rubs off easily. 5. FeCls . 6. KOH . 
 
 DIFF. Col. Chem. 2. 
 
 See note under enargite, page 95. 
 
 ENARGITE See page 95. 
 
 is 
 1 
 
 s 
 
RA 
 
 HNOt 
 
 FAMATINITE 
 
 COL. White. With galena, decidedly pinkish white; with enargite, 
 
 distinctly pinkish white; with luzonite, about the same. 
 HARD. Medium. SURF. Smooth. H. 3.5. 
 
 CHEM. 1. HNOs. Very slowly etched, turning brown, some parts 
 
 more rapidly than others; at last iridescent. Fumes tarnish faintly. 
 
 Rather persistent, shows etched surface. 2. KCN. Rather quickly 
 
 brown, then iridescent, slowly, and is etched. Rubs to grayish 
 
 brown, etched surface. 3. HC1 . 4. Aq. Reg. Rather quickly 
 
 brown, slight effervescence. Fumes tarnish. Rubs clean quite 
 
 easily. 5. FeCls . 6. KOH . 
 
 DIFF. Col. Chem. 1, 2. 
 
 NOTE. See note under enargite, page 95. A pink mineral from 
 Goldfield, carrying equal parts of As and Sb, with the com- 
 position of an enargite, shows the following behavior: 1. HNOa 
 
 . Fumes tarnish faintly. 2. KCN. Very quickly dark 
 
 brown, then black. Etches deeply. 
 
 3 
 
 OJ 
 
 ARGYROPYRITE See page 101. Jg 
 
 Cft 
 GEOCRONITE See page 132. Cfl 
 
 z 
 
 BREITHAUPTITE See page 66. Q 
 
 Qtf 
 
 V) 
 CO 
 
 UJ 
 
 Q 
 tt 
 
 99 
 
WHITE 
 
 HAKDNESS MEDIUM 
 
 CHEAMY WHITE 
 
 No Eff. HNO 8 
 
 PENTLANDITE (FeNi)S 
 
 COL. Creamy white. With galena, very pale (creamy) yellow, not 
 
 brown; with silver, about the same as with galena. 
 HARD. Medium. SURF. Shiny. H. 3.5-4 < po > cp. 
 
 CHEM. 1. HNOa. Slowly light yellowish brown tarnish ; rubs off . 2. 
 
 HNOs cone. Slowly tarnishes bright yellow; rubs clean easily. 3. 
 
 KCN . 4. HC1 cone. . 5. Aq. Reg. Quickly bright brown, 
 
 fumes slightly brown ; rubs clean easily. 6. FeCls . 7. KOH . 
 
 S.NaOH . 9. (NH 4 ) 2 S X . 10. H 2 SO4 cone. . ll.K3Fe(CN) 6 
 
 . 12. K 4 Fe(CN) 6 . 13. Iodine . 
 
 DIFF. Chem. 1, 2. 
 
 SULVANITE See page 72. 
 CHALMERSITE See page 72. 
 BRONZE ENARGITE See page 74. 
 
 BERTHIERITE See page 103. 
 LINNJEITE See page 79. 
 HAUCHECORNITE See page 79. 
 
 100 
 
RA 
 
 Eff. HNOs 
 
 i 
 
 ARGYROPYRITE Ag, Fe, S and As ? 
 
 COL. White. With galena, pale creamy white; with silver, same as 
 
 silver. 
 
 HARD. Medium. SURF. Smooth or slightly rough. H. 3.5-4 > arsenic. 
 CHEM. 1. HNOs. Slowly blackens, with effervescence; rubs off to 
 
 black and rough surface. 2. KCN . 3. HC1 . 4. AQ. Ree. 
 
 5. FeCb . 6. KOH . 
 
 DIFF. Chem. 1. 
 
 NOTE. Intermediate between argentopyrite and sterabergite, 
 in composition. 
 
 AIKINITE PbCuBiSa 
 
 COL. White. With galena, pale creamy; with silver, very pale 
 
 grayish white. 
 
 HARD. Medium or low. SURF. Smooth. H 2-2.5. > bn. 
 
 CHEM. 1. HNO 3 . Effervesces and blackens, shows whitish coating 
 
 (yellow and white mixed) on surface by oblique light. Fumes tarnish 
 
 instantly iridescent then blacken. 2. KCN . 3. HC1 . 4. HC1 
 
 cone. Instantly dark brown, persistent. 5. Aq. Reg. Turns brown IT* 
 
 with slow effervescence, blackens. Rubs gray and rough. Shows UJ 
 
 slight white coating. Fumes tarnish instantly bright brown. 6. 
 
 DIFF. Col Chem. 2. y* 
 
 CD 
 ED 
 
 DOMEYKITE See page 125. ^ 
 
 ALGODONITE (CREAM) See page 74. C 
 
 MOHAWKITE (CREAM) See page 74. 
 WHITNEYITE See page 75. 
 KALLILITE See page 82. 
 
 3 
 
 CD 
 
 CD 
 
 UJ 
 
 Q 
 
 
a 
 
 I 
 
 WHITE 
 
 HARDNESS MEDIUM 
 
 GALENA WHITE 
 
 S 
 
 KOH Neg. 
 
 
 1 
 
 1 
 
 CHALCOSTIBITE CttSbSa 
 
 COL. White. With galena, very pale grayish white. 
 
 HARD. Medium. SURF. Smooth. H. 3-4. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 . 4. Aq. Reg. Fumes 
 
 instantly tarnish narrow rim bright. Acid slowly very faint brown- 
 ish gray. Rubs clean easily. 5. FeCla . 6. KOH . 
 
 DIFF. Chem. 6. 
 
 BOURNONITE See page 92. 
 POLYBASITE See page 105. 
 GEOCRONITE See page 132. 
 KALLILITE See page 82. 
 
 H! 
 
 S 
 
 1 
 
 I 
 I 
 
 102 
 
KOH 
 
 BERTHIERITE FeSb 2 S 
 
 COL. White. With galena, practically the same; with silver, like 
 
 galena. 
 
 HARD. Medium. SURF. Smooth. H. 2-3. 
 
 CHEM. 1. HNOs - . KCN - . 3. HC1 cone. - . 4. Aq. Reg. 
 
 Effervesces and turns slowly bright yellowish brown; fumes tarnish, 
 
 rubs clean easily. 5. FeCls - . 6. KOH. Slowly bright brown. 
 
 7. NaOH Same as KOH, but more quickly. 
 DIFF. Chem. 1, 6. 
 
 GUEJARITE 
 
 COL. White. With galena, nearly the same (faintly creamy). 
 
 Shows two colors, grayer and whiter (probably due to orientation). 
 
 HARD. Medium. SURF. Smooth. ^, 
 
 CHEM. 1. HNOs. Quickly bright iridescent, then blackens. Rubs 2 
 
 easily to gray, roughened surface. 2. KCN. Slowly faint brown. 
 
 Rubs clean easily. 3. HC1 - . 4. Aq. Reg. Slowly bright irides- S< 
 
 cent. Slowly efferyesces. Rubs clean easily. 5. FeCls - . 6. 
 
 KOH. Instantly iridescent, then blackened rapidly. Coated with 
 
 yellow. Rubs off clean to show deeply dissolved and roughened 
 
 surface. 5? 
 
 DIFF. Chem. 6. 
 
 NOTE. Observations were made on minute crystals mounted in CO 
 
 sealing wax, so that reactions may be somewhat affected. (/) 
 
 01 
 O 
 
 s 
 
 EH 
 
 z; 
 
 Q 
 
 e 
 
 103 
 
WHITE 
 
 HARDNESS Low 
 GRAYISH WHITE 
 HNO 3 NEG. 
 
 KCN Neg. 
 
 MOLYBDENITE MoS 2 
 
 COL. White. With galena, mixture of dull grayish white (with 
 purple tinge), and white; with silver, mixture of dull purplish gray 
 and white. Different colors due to different orientation? 
 
 HARD. Low. SURF. Smooth. H. 1-1.5 > cc.? 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 . 4. Aq. Reg. . 5. 
 
 FeCla . 6. KOH . 7. NH 4 OH . 
 
 DIFF. Col. Chem. 1, 2, 4. 
 
 REGNOLITE Cu 7 As 2 Si 2 
 
 COL. Grayish white. With galena, greenish grayish white; with 
 
 tetrahedrite, pale greenish. 
 
 HARD. Low. SURF. Smooth. H. < SI. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 . 4. Aq. Reg. 
 
 Rather slowly bright brown. Fumes tarnish faintly. Rubs clean 
 
 easily. 5. FeCls . 6. KOH . 
 
 DIFF. Chem. 4. 
 
 SELIGMANNITE CuPbAsS 3 
 
 COL. White. With galena, grayish white; with tetrahedrite, very 
 
 slightly lighter. 
 
 HARD. Low. SURF. Smooth. H. = 3. 
 
 CHEM. 1. HNOs . 2. KCN . 3. HC1 . 4. Aq. Reg. Very 
 
 quickly blackens with effervescence. Thinly coated with white. 
 
 Rubs to rough gray surface. 5. FeCls . 6. KOH. Rather 
 
 slowly darkens to pale bluish iridescent. Rubs clean easily. 
 DIFF. Chem. 6. 
 
 NOTE. Practically the same as rathite in chemical properties. 
 
 ARGENTIFEROUS JAMESONITE (near Brogniardite) 
 
 COL. White. With galena, pale grayish white. 
 
 HARD. Low. SURF. Smooth. H. < cp. 
 
 CHEM. 1. HNOs . Fumes slowly faint brown. 2. KCN ? (or 
 
 possibly very faint gray). 3. HC1 . 4. Aq. Reg. Effervesces 
 
 slightly, and turns brown and iridescent. Fumes tarnish instantly. 
 
 Rubs to faint gray, roughened surface. 5. FeCls . 6. KOH . 
 
 DIFF. Chem. 4. 
 
 NOTE. This mineral is distinctly browner than ordinary jame- 
 sonite, and does not agree in properties with any other mineral 
 in this collection. 
 
 CINNABAR See page 141. 
 
 KALGOORLITE See page 124. 
 
 BOURNONITE See page 92. 
 
 TIEMANNITE See page 114. 
 
 CQ RATHITE See page 141. 
 
 ^ LENGENBACHITE See page 141. 
 
 t UNKNOWN (Tonopah) See page 114. 
 
 1 
 
 U< 104 
 
KCN 
 
 ORPIMENT As 2 S 3 
 
 COL. White. With galena, pale grayish white; with proustite, pale J? 
 
 (purplish) grayish white; with tetrahedrite, dull bluish gray; with O 
 
 cuprite, same as with proustite? Transparent yellow by oblique ^ 
 
 light. XH 
 
 HARD. Low. SURF. Smooth. H. 1.5-2. 
 
 CHEM. 1. HNO 3 - . 2. HNO 3 cone. - . 3. KCN. Quickly dark, 
 persistent. 4. HC1 cone. - . 5. Aq. Reg. Fumes darken? 6. 
 FeCl 3 - . 7. KOH. Instantly blackens and dissolves. 8. (NH 4 ) 2 S X . 
 Dissolves and forms rough surface. 9. K3Fe(CN) 6 - . 
 
 DIFF. Col. Chem. 3, 4. 
 
 ARGYRODITE AgeGeSs 
 
 COL. White. With galena, dull grayish white; with tetrahedrite, 
 
 very pale bluish gray, no brown. 
 
 HARD. Low. SURF. Smooth. H. 2 5 
 
 CHEM. l.'-.HNOs - . 2. KCN. Rather quickly brown, developing 
 
 structure by differential attack. Rubs easily to a faintly etched 
 
 surface. 3. HC1 - . 4. Aq. Reg. Instantly iridescent; rubs bright 
 
 iridescent, persistent. 5. FeCls - . 6. KOH - . 
 DIFF. Chem. 2, 4, 5. 
 
 POLYBASITE Ag 9 SbS 6 
 
 COL. White. With galena, very pale grayish (greenish) white; with 
 
 silver, bluish grayish white; with argentite, practically white; with 
 
 tetrahedrite, grayish white, no brown. Color is slightly variable. 
 HARD. Low. SURF. Smooth. H. 2-3 = gn 
 
 CHEM. 1. HNO 3 - . 2. KCN. Rather quickly dark brown, then black ; 
 
 persistent, shows much roughened surface, sometimes with structure 
 
 developed. 3. HC1 - . 4. HC1 cone. Fumes sometimes blacken, 
 
 but this varies with different specimens, and some polybasite is not 
 
 affected even by fumes. 5. Aq. Reg. Iridescent, with very slow 
 
 effervescence, and not much tarnishing by fumes. Rubs clean, 
 
 leaving a somewhat roughened surface, usually. 6. FeCl 3 - . 7. 
 
 KOH - . 8. (NH4)2S X . Very slowly blackens, partially? This 
 
 test is doubtful. 
 DIFF. Chem. 2, 5, 6. 
 
 PEARCEITE Ag 9 AsS, 
 
 COL. Grayish (greenish) white. With galena, very pale grayish Z 
 
 green. M 
 
 HARD. Low. SURF. Smooth. H. 3 = gn. ** 
 
 CHEM. 1. HNO 3 - . Fumes tarnish; tarnish washes off. 2. KCN. Very 
 
 uickly blackens and dissolves. Rubs to pale gray, rough surface. 
 H 9l l " ' 4 - HC1 conc - - 5 - M- Reg. Instantly effervesces, 
 
 turns iridescent, and darkens quickly. Rubs clean very easily. 6. p^ 
 
 FeCls. Quickly bright iridescent. Rubs clean easily. 7. KOH - . ^ 
 
 DIFF. Chem. 6. Q 
 
 JALPAITE See page 140. ^ 
 
 MIARGYRITE See page 115. C/) 
 
 STEPHANITE See page 142. J 
 LIVINGSTONITE See page 142. 
 
 105 
 
WHITB 
 
 HARDNESS Low 
 GRAYISH WHITE 
 HNOs 
 FeCls 
 
 KCN Weg. 
 
 TEALLITE PbSnSa 
 
 COL. White. With galena, creamy (?) grayish white; with tetra- 
 
 hedrite, slightly lighter. 
 
 HARD. Low. SURF. Smooth. H. 1-2. 
 
 CHEM. 1. HNOs. Bright brown, then brilliant iridescent, some grains 
 
 quickly, some more slowly. Rubs clean easily. 2. KCN - . 3. 
 
 HC1. Slowly yellowish brown, fumes tarnish. Rubs clean easily. 4. 
 
 Aq. Reg. Instantly iridescent, with effervescence; darkens, fumes 
 
 tarnish. Rubs to gray, persistent. 5. FeCls. Slowly faint brown. 
 
 6. KOH. Slowly faint brown. 
 DIFF. Chem. 1, 3. 
 
 AGUILARITE AgzS-AgzSe 
 
 COL. White. With galena, pale gray, with greenish tinge (?) ; with 
 
 silver, dull pale grayish white. 
 
 HARD. Low. SURF. Smooth. H. 2.5 < cp. 
 
 CHEM. 1. HNO 3 . Slowly tarnished brownish, rubs off very easily. 2. 
 
 KCN - . 3. HC1 - . 4. HC1 cone. - . 5. Aq. Reg. - ? 6. 
 
 FeCls. Slowly bright iridescent, rubs clean easily. 7. KOH - . 
 DIFF. Chem. 1, 3, 5. 
 
 (PETZITE ? unknown) ? 
 
 COL. White. With galena, purplish grayish white; with silver, de- 
 
 cidedly purplish grayish white. 
 
 HARD. Low. SURF. Smooth. H. 2.5-3 < gold. 
 
 CHEM. 1. HNOs. Instantly blackens, rubs to gray. 2. KCN - . 3. 
 HC1 - . 4. Aq. Reg. Instantly bright iridescent, rubs clean. 5. 
 FeCh. Instantly iridescent; fairly persistent, dries bright. 6. 
 KOH - . 
 DIFF. Chem. 1, 3, 4. 
 
 NOTE. Not true petzite, and usually with native gold. For 
 petzite, see page 137. 
 
 COLORADOITE HgTe 
 
 COL. Grayish white. With galena, dull pale gray; with silver and 
 tetrahedrite, same; same color as petzite (?). 
 
 HARD. Low. SURF. Smooth. H. 3. 
 
 CHEM. 1. HNOs. Very slowly bright brown, then brilliant iridescent; 
 rubs clean. 2. KCN - . 3. HC1 - . 4. Aq. Reg. Slowly bright 
 iridescent, with effervescence; rubs clean easily. 5. FeCla. Slowly 
 faint brownish. Tarnished at edges of drop, rubs clean easily. 6. 
 KOH - . 
 
 DIFF. Chem. 1,3,4, 5. 
 
 I 
 
 fc 
 
 g 
 I 
 
 106 
 
KCN 
 CHALCOCITE Cu 2 S 
 
 COL. Grayish or bluish white. Sometimes "mottled," with bright 
 colors, blue or green. With galena, pale bluish or grayish white; 
 with silver, pale bluish white; with cuprite, slightly whiter. 
 HARD. Low. SURF. Smooth. H. 2.5-3 < bn. 
 
 CHEM. 1. HNOs. Effervesces vigorously and etches, turning more or 
 less blue. Develops cleavage or irregular cracking. 2. HNOa cone. 
 Effervesces, turns blue, and dissolves, very rapidly, but does not 
 develop cleavage. 3. KCN. Very rapidly blackens, rubs off to show 
 cleavage or cracking, very fine graixied. Dilute KCN. Produces 
 coarser etching. 4. HCJi. Change's color slightly and dissolves a 
 little. 5. HC1 cone. Same as HC1. 6. Aq. Reg. Dissolves readily, 
 effervesces and develops cleavage, but changes color only slightly. 
 7. FeCls. Dissolves and turns slightly paler (?). Does not develop 
 
 structure. 8. KOH . 9. NaOH . 10. NHiOH . 11. 
 
 K3Fe(CN) 6 . 12. K 4 Fe(CN) 8 . Slowly faint brown. 
 
 DIFP. Col. Chem. 1. 
 
 NOTE. Color variation of chalcocite is due partly to admixture 
 of covellite in sub-microscopic fragments or solid solution. The 
 reds and greens sometimes observed may not be due to this. 
 "Mottled" chalcocite of this sort shows true chalcocite cleav- 
 age on etching. 
 
 e CLEAVAGE. The writer has found by etching oriented sec- 
 tions of chalcocite crystals that this mineral possesses good 
 cleavages parallel to the base and side pinacoid, and a poor one 
 parallel to the front pinacoid. Therefore, no section will show 
 more than two good cleavage directions, and will much more 
 often show one good cleavage and one poor one. This affords 
 a sure distinction between chalcocite which has its own crystal 
 form, and chalcocite derived from bornite, which retains the 
 structure of the bornite. In this case any section will show at 
 least three directions of cleavage, of equal perfection though not 
 necessarily equally abundant in development. These are octa- 
 hedral directions. It has not been observed in unaltered bornite, 
 but only when bornite is altering to chalcocite apparently under 
 special conditions. 
 
 Anomalous cleavages have been noted in chalcocite crystals 
 from certain localities, and these are not yet fully explained. 
 
 When in too small grains to show much cleavage, there is 
 often a tendency for a single cleavage direction to be revealed, 
 though the smaller areas do not show even this. 
 
 The hardness of chalcocite is slightly variable in different 
 crystallographic directions. 
 
 UNKNOWN " TAPALPAITE " (GRAY) ? 
 
 COL. Grayish white. With galena, grayish white. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs. Slowly iridescent, with effervescence, coated with 
 
 white. Rubs clean. 2. KCN. Slowly darkens. Rubs clean. 3. 
 
 HC1 . 4. Aq. Reg. Instantly effervesces and turns iridescent. 
 
 Fumes tarnish iridescent. Rubs clean easily. 5. FeCla. Instantly 
 
 iridescent, brilliant. Coated thinly with white? Rubs clean. 6. 
 
 KOH . 
 
 DIFF. Chem. 1. ^S? 
 
 ARGENTITE Ag 2 S ~ 
 
 COL. Grayish white. With galena, dull pale grayish white; with 
 
 silver, same; with tetrahedrite, duller gray, no brown tinge; with 3C 
 
 enargite, very pale greenish, no pink tinge; with polybasite, very 
 
 pale (greenish) gray; with stephanite, very pale greenish yellow; 
 
 with dyscrasite, very dull gray. 
 
 HARD. Low. SURF. Smooth, but easily scratched. H. 2-2.5 <=gn. 
 CHEM. 1. HNOs. Slowly light brown; fumes tarnish faintly; rubs off 
 
 easily, and shows structure by differential etching. 2. HNOs cone. 
 
 . 3. KCN. Slowly or quickly dark brown, rubs off readily. ^ 
 
 Sometimes only faint brown, slowly. 4. HC1 . 5. HC1 cone. -J 
 
 Instantly tarnished iridescent by the fumes, and blackened by 
 
 acid, forming a thick, persistent tarnish film. 6. Aq. Reg. In- CrJ 
 
 stantly iridescent. Fumes tarnish brighter than acid, persistent. t/) 
 
 7. FeCls Slowly turns brown, dries iridescent; rubs off. 8. KOH 
 
 . 9. NaOH . 10. (NH<) a S x . ^ 
 
 DIFF. Chem. 3, 6, 7. ~* 
 
 NOTE. With much galena; Aq. Reg. doea not tarnish argentite Q 
 
 so quickly or so much. Q^ 
 
 STROMEYERITE See page 117. < 
 
 PEARCEITE Bee page 105. 
 
 107 
 
WHITE 
 
 HARDNESS Low 
 GRAYISH WHITE 
 HNOs 
 FeCl 3 NEG. 
 
 HC1 Neg. 
 
 Q STANNITE SnCu 2 FeS 4 (Hintze) 
 
 ^ [(Sn, Cu, Fe, Zn)S] 
 
 COL. Pale olive gray. With galena, pale yellowish brown, or greenish 
 
 ** gray; with silver, pale dull brownish gray, or yellowish gray; with 
 
 W tetrahedrite, dull brownish gray. Color is apparently variable, from 
 
 ^) different localities. 
 
 ** HARD. Low. SURF. Smooth. H. 4 = cp. 
 
 CHEM. 1. HNOs. Quickly brown, then brilliant iridescent; rubs off. 
 2. HNOs cone. Darkens quickly, then turns green, and effervesces, 
 washes off black showing solution surface. Rubs clean, showing 
 differential solution. 3. KCN . HC1 . Fumes tarnish brown- 
 ish. 4. HC1 cone. Same as HC1. 5. Aq. Reg. Instantly effervesces 
 and turns iridescent; develops grains; rubs clean easily. 6. FeCls 
 
 . 7. KOH . 8. NaOH . 9. (NHO^S* . 10. NH 4 OH 
 
 . 11. K3Fe(CN) 6 . Slowly faint brown, dries darker, rubs off 
 
 easily. 
 DIFF. Chem. 1, 7. 
 
 BAUMHAUERITE Pb 4 As 6 Si3 
 
 COL. White. With galena, pale grayish white; with tetrahedrite 
 
 light grayish white, no brown. 
 
 HARD. Low. SURF. Smooth. H. 3. 
 
 CHEM. 1. HNOs. Very slowly turns some portions light brown, others 
 
 much less easily; rubs off easily. 2. KCN . 3. HC1 . 4. 
 
 Aq. Reg. Instantly iridescent, blackens with effervescence; rubs to 
 
 persistent black. 5. FeCl 3 . 6. KOH. Quickly iridescent, with 
 
 rapidly changing colors; rubs clean easily. 
 DIFF. Chem. 1, 6. 
 
 REALGAR AsS 
 
 COL. White. With galena, dull grayish white; with proustite, 
 
 faintly purplish grayish white. Transparent orange by oblique light. 
 
 HARD. Low. SURF. Smooth. H. 1.5-2. 
 
 CHEM. 1. HNOs. Effervesces but does not change color. 2. HNO 3 
 
 cone. Same. 3. KCN . 4. HC1 . 5. Aq. Reg. Effervesces, 
 
 turns brown and darkens, rubs to rough gray. 6. FeCls . 7. 
 
 KOH. Instantly brown, then blackens and dissolves very rapidly. 
 
 8. (NH 4 ) 2 S X . 9. K 3 Fe(CN) 6 . 
 
 DIFF. Col. Chem. 1, 7. 
 
 NOTE. Realgar with lorandite from Macedonia is transparent 
 red by oblique light. Also is blackened, without effervescence, 
 by HNOs; and is slowly blackened by KOH. 
 
 CROOKESITE (CuTlAg) 2 Se 
 
 COL. Grayish white. With galena, grayish (brownish) white; with 
 
 tetrahedrite, practically the same. 
 
 HARD. Low (medium) . SURF. Smooth. H. = 2.5-3. 
 
 CHEM. 1. HNOs. Slowly faint brown. Fumes instantly light brown. 
 
 Rubs clean easily. 2. KCN ? (test not positive). 3. HC1 . 
 
 4. Aq. Reg. . 5. FeCla . 6. KOH ? (possibly very faint 
 
 brown, doubtful). 
 DIFF. Col. Chem. 1. 
 
 108 
 
 1 
 
RA 
 
 I 
 
 m 
 
 FREIESLEBENITE See page 134. 
 GUANAJUATITE See page 120. 
 ANDORITE See page 134. 
 UNKNOWN (near Andorite) See page 134. 
 
 
 
 z 
 
 E 
 
 109 
 
 I 
 
 LU 
 Q 
 
WHITE 
 
 HARDNESS Low 
 GRAYISH WHITE 
 HNO 
 FeCla NBG. 
 
 Fumes HC1 
 
 . CYLINDRITE 3 PbSnS 2 + SnFeSb 2 S 8 
 
 COL. White. With galena, pale grayish white; with tetrahedrite, 
 ^, almost the same, but no brown. 
 
 ^ HARD. Low. SURF. Smooth. H. 2.5-3. 
 
 w CHEM. 1. HNOs. Slowly brown, then iridescent; rubs clean. Fumes 
 
 Q tarnish slightly. 2. KCN . 3. HC1 . Fumes tarnish pale 
 
 QJ brown. 4. Aq. Reg. Immediately brown, then iridescent; rubs 
 
 {> clean easily. Fumes tarnish. 5. FeCla . 6. KOH. Slowly brown, 
 
 then iridescent; rubs clean easily. 
 DIFF. Chem. 1, 6. 
 
 FRANKEITE 3 PbSnS 2 + Pb 2 FeSb 2 S 8 
 
 COL. White. With galena, creamy grayish white; with silver, pale 
 
 grayish white; with tetrahedrite, very close, but a little lighter. 
 HARD. Low. SURF. Smooth. H. 1-2. 
 
 CHEM. 1. HNOa. Rather quickly brown, then brilliant iridescent; 
 
 rubs clean easily. 2. KCN . 3. HC1 . Fumes tarnish slightly. 
 
 4. Aq. Reg. Instantly iridescent, effervesces a moment; rubs clean 
 
 easily. Fumes tarnish bright. 5. FeCla . 6. KOH. Slowly pale 
 
 brown, rubs clean. 
 DIFF. Chem. 1, 6. 
 
 BROGNIARDITE PbAg 2 Sb 2 S 6 ? 
 
 COL. White. With galena, pale (bluish) white; with tetrahedrite, 
 distinctly bluish white. 
 
 HARD. Low. SURF. Smooth. H. = gn? 
 
 CHEM. 1. HNO 3 . Slowly pale brown (differentially) ; rubs clean easily. 
 2. KCN. Slowly faint brown (uniform) ; rubs clean easily. 3. HC1. 
 Very faint brown, slowly. Fumes tarnish light brown. Rubs clean 
 easily. 4. Aq. Reg. Immediately effervesces and turns iridescent, 
 darkening and developing a white coating. Fumes tarnish brilliant 
 iridescent. Rubs to gray rough surface. Fumes rub clean. 5. 
 
 FeCla . 6. KOH. Instantly bright iridescent; rubs clean easily, 
 
 showing etched surface. 
 
 DIFF. Chem. 1, 6. 
 
 NOTE. Close to jamesonite. 
 
 JAMESONITE Pb 2 Sb 2 S 6 
 
 COL. White. Mixture of grayish and pale creamy whites, the gray 
 decidedly harder. Act about the same chemically and appear to be 
 differently oriented individuals. With galena, decidedly grayish 
 creamy white, and almost same; with silver, same as with galena; 
 with tetrahedrite, slightly grayer, and pure white. 
 
 HARD. Low. SURF. Smooth. H. 2-3. 
 
 CHEM. 1. HNOs. Instantly brown, then black. White coating shown 
 by oblique light. Rubs easily to brilliant iridescent, persistent. 2. 
 KCN - . 3. HC1 - . Fumes tarnish slowly bright; rubs easily to 
 faint brown, persistent. 4. Aq. Reg. Rather quickly brown, with 
 effervescence, then blackens. Gray quicker than white. Yellowish 
 coating formed ; rubs to gray rough surface. Fumes tarnish brilliant 
 iridescent. 5. FeCk - . 6. KOH. Slowly blue and purple tarnish, 
 white less touched, and some gray grains more than others. 
 
 DIFF. Chem. 1, 4, 6. 
 
 
 1 
 
RA 
 
 ZINKENITE PbSbzS, 
 
 COL. White. With galena, pale grayish white; with tetrahedrite, 
 lighter grayish white, no brown ; with j amesonite, about same, may 
 be a little bluer. Color slightly variable, due to different orienta- 
 tion of individuals. 
 
 HARD. Low. SURF. Smooth. H. 3 +. 
 
 CHEM. 1. HNOs. Quickly blackens with effervescence, rubs to irides- 
 cent gray, rough. 2. KCN . 3. HC1 . Fumes slowly tarnish 
 
 brown. 4. Aq. Reg. Instantly brown, then black; rubs to gray 
 
 rough surface. Fumes tarnish instantly. 5. FeCla . 6. KOH. 
 
 Some grains instantly iridescent; some untouched. Rubs easily to 
 pale colors. 
 
 DIFF. Chem. 1, 4, 6. 
 
 
 
 z 
 
 K 
 
 I 
 
 V) 
 CO 
 LU 
 Z 
 
 Q 
 
 111 
 
WHITE 
 
 HARDNESS Low 
 GRAYISH WHITE 
 HN0 8 
 FeGl Ncu 
 
 HC1 
 
 I 
 I 
 
 ALABANDITE See page 96. 
 COSALITE See page 122. 
 
 ss 
 I 
 
 I 
 
 112 
 
RA 
 
 ... 
 
 d 
 
 z 
 
 E 
 
 1 
 
 UJ 
 
 Q 
 
 113 
 
1 
 
 WHITE 
 
 HARDNESS Low 
 BLUISH WHITE 
 HNOjNuo. 
 
 KOH Neg. 
 
 TIEMANNITE HgSe 
 
 COL. White. With galena, distinctly pale blue; with silver, pale 
 
 blue, darker than with galena. 
 
 HARD. Low. SURF. Smooth. H. 2.5. 
 
 CHEM. 1. HNO 3 - . 2. HNO 3 cone. - . 3. KCN - . 4. HC1 - . 
 
 5. HC1 cone. - . 6. Aq. Reg. Rapidly blue, red, iridescent, then 
 coated with orange yellow, rubbing to uniform gray. 7. FeCls - . 
 8. KOH - . 9. (NH 4 ) 2 S X . Very slowly brown, rubs clean. 10. 
 NH4OH . ll.K4Fe(CN)e - . 12. K3Fe(CN) 6 - . 13. Iodine. 
 Bright iridescent; rubs to persistent gravish green. 
 
 DIPF. Chem. 1, 6, 7. 
 
 ONOFRITE Hg(SSc) 
 
 COL. White. With galena, pale bluish white; with cuprite, bluish 
 white, makes latter look creamy; with tiemannite, same. Shows 
 intergrowth of whiter and browner portions, showing crystal out- 
 lines. May be due to different orientation. 
 
 HARD. Low. SURF. Smooth. H. 2.5. 
 
 CHEM. 1. HNOs - . 2. KCN. Faintly blue and roughens. Rubs 
 clean, showing shallow solution pit. 3. HC1 - . 4. Aq. Reg. 
 Quickly iridescent, growing brilliant; effervesces; finally coated with 
 yellow. Rubs clean, showing deeply etched surface. 5. FeCls - . 
 
 6. KOH - . 
 DIFF. Chem. 2, 4, 5. 
 
 POLYARGYRITE 
 
 COL. Bluish white. With galena, pale blue; with cuprite, bluish 
 
 greenish gray, grayer than cuprite. 
 
 HARD. Very low. SURF. Smooth. H. 2.5 <3C cp. 
 
 CHEM. 1. HNOa - . Fumes^tarnish. When with chalcopyrite, tar- 
 nishes slightly brown and iridescent. Rubs clean easily. 2. KCN. 
 Instantly turns brown. Dries brilliant iridescent when rinsed off. 
 Rubs clean rather easily. 3. HC1 - . 4. Aq. Reg. Instantly bril- 
 liant iridescent, with effervescence. Fumes tarnish brilliant iri- 
 descent. Rubs clean easily. 5. FeCla. Rather quickly darkens and 
 
 r ^ appears to roughen. Rinses off to brilliant iridescent. Rubs clean 
 
 Cq easily. 6. KOH - . 
 
 S-, DIFF. Chem. 2, 5. 
 
 1C; STUTZITE Ag4Te ? 
 
 ^ COL. White. With galena, very pale bluish white. 
 
 * HARD. Low. SURF. Smooth. H. = tellurium. 
 
 ^ CHEM. 1. HNO 3 - . 2. KCN - . 3. HC1 - . 4. Aq. Reg. Effer- 
 
 5j vesces and slowly turns bright iridescent then dark. Rubs easily to 
 
 ff) gray iridescent surface, roughened, and spotted with minute clean 
 
 < areas. 5. FeCla - . 6. KOH - . 
 
 j^ DIFF. Chem. 4. 
 
 3 UNKNOWN (silver mineral, Tonopah, Nev.) ? 
 
 ^ COL. Bluish white. With galena (grayish), bluish white; with silver, 
 
 bluish white. 
 
 HARD. Low. SURF. Ragged. H < silver. 
 
 CHEM. 1. HNO 3 - . Fumes tarnish slightly. 2. KCN - . 3. HC1 - . 
 4. HC1 cone. - . Fumes tarnish slightly. 5. Aq. Reg. Instantly bril- 
 liant iridescent. Fumes same, rubs clean easily. 6. FeCla. Slowly 
 darkens and turns iridescent. Rubs clean easily. 7. KOH - . 
 DIFF. Chem. 2, 6. 
 
 fY> NOTE. Same as polyargyrite except that it does not effervesce 
 
 *U with Aq. Reg., and is not attacked by KCN. 
 
 COVELLITE See page 58. 
 KALGOORLITE See page 124. 
 RATHITE See page 141. 
 CINNABAR See page 141. 
 
 114 
 
RA 
 
 KOH 
 PROUSTITE AgsAsSi 
 
 COL. Bluish white. With galena, bluish white; with cuprite, about 
 
 the same. Transparent brilliant red with oblique light. 
 HARD. Low. SURF. Smooth. H. 2.5 = gn. 
 
 CHEM. 1. HNO 3 . 2. HNOs cone. . 3. KCN. Slowly light 
 
 brown, developing scratches. When rinsed off, without rubbing, 
 
 shows little or no orange yellow jjoating, rubs clean easily. 4. 
 
 HC1 . 5. HC1 conc.-r . 6. Aqf Reg. Brown, then iridescent, 
 
 then effervesces slowly, and blackens. Rubs easily to persistent 
 
 light brown. Fumes tarnish. 7. FeCls. Slowly faint tarnish? 8. 
 
 KOH. Instantly brown, quickly darkening. Rubs to pale yellowish 
 
 roughened surface. 9. NaOH. Same as KOH. 10. (NH 4 ) 2 S X . 
 
 Slowly faint brown, rubs off clean. 11. NH*OH . 12. K*Fe(CN) 
 
 . 13. KsFe (CN) 6 . 
 
 DIFF. Col. Chem. 3. Jr 
 
 NOTE. The presence of some Sb probably accounts for any coat- 
 ing with KCN. Q 
 
 PYRARGYRITE AgsSbSs 
 
 COL. Bluish white. With galena, pale bluish white; with proustite, 
 
 slightly lighter? Transparent brilliant red by oblique light. 
 HARD. Low. SURF. Smooth. H. 2.5 = gn. 
 
 CHEM. 1. HNOs . 2. HNOs cone. . 3. KCN. Slowly light 
 
 brown, developing scratches. When rinsed off, shows orange yellow 
 
 coating, rubs off, leaving solution pit. 4. HC1 . 5. HC1 cone. . 
 
 6. Aq. Reg. Brown, then iridescent, then effervesces slowly and 
 blackens. Rubs easily to light brown, persistent. Fumes tarnish. 
 
 7. FeCls. Dissolves (?) slightly, but does not change color. 8. 
 KOH. Instantly iridescent, and immediately blackens and dissolves. 
 Rubs off to show solution pit colored pale brownish yellow. 9. 
 NaOH. Same as KOH. 10. (NH 4 ) 2 S X . Slowly faint brown, rubs off 
 clean. 11. NH 4 OH . 12. K4Fe(CN) 8 . 13. KsFe(CN) 6 . 
 
 DIFF. Col. Chem. 3. 
 
 UNKNOWN (Bluish white, with sternbergite, from Joachimsthal) ^ 
 
 COL. Bluish white. With galena, pale bluish white; with silver, de- 
 cidedly bluish white. 
 
 HARD. Very low. SURF. Smooth. H. = cc.? 
 
 CHEM. 1. HNOs . 2. KCN. Darkens to gray, develops structure. 
 
 3. HC1 . 4. Aq. Reg Black and iridescent, persistent. 5. KOH. 
 
 Rapidly iridescent, then black. Rubs clean showing solution sur- 
 face. 6. FeCls . 
 
 DIFF. Col. Chem. 2, 4. 
 
 NOTE. Possibly near miargyrite. 
 
 VRBAITE TlAs 2 SbS 6 
 
 COL. Bluish white. About like cuprite. Transparent red by oblique 
 
 light. 
 
 HARD. Low. SURF. Smooth. 
 CHEM. 1. HNOs . 2. KCN . 3. HC1 . 4. Aq. Reg. Quickly 
 
 effervesces and blackens. Rubs to gray, rough surface. 5. FeCls 
 
 . 6. KOH. Instantly iridescent. Rubs to persistent gray, 
 
 roughened surface. 
 DIFF. Chem. 2. 
 
 MIARGYRITE AgSbS 2 Q j 
 
 COL. White. Faintly mottled, in various shades, like chalcocite. *p 
 
 With galena, bluish white; with silver, bluish white. Deep red " * > 
 
 transparent with bright oblique light. ^ 
 
 HARD. Low. SURF. Smooth. H. 2-2.5. C 
 
 CHEM. 1. HNOs . 2. KCN. Slowly pale brown, rubs faint, per- ( 
 
 sistent. 3. HC1 . 4. Aq. Reg. Quickly brown, with effervescence, 
 
 then iridescence. Yellowish white coating formed. Rubs to gray, y* 
 
 roughened surface. Fumes tarnish slowly, bright iridescent. 5. ' CT 
 
 FeCls . 6. KOH. Instantly iridescent, with rapid change of J 
 
 colors to higher orders, the last stage brownish gray and dark brown. ) ** 
 
 Rubs to gray, rough surface, showing differential solution; white Z 
 
 usually more resistent. 
 
 DIFF. Col. Chem. 2,4. ) 
 
 STEPHANITE See page 142. 9 
 
 115 - 
 
 d 
 
WHITE 
 
 HARDNESS Low 
 BLUISH WHITE 
 HNOs 
 
 KCN Neg 
 
 UNKNOWN " Purple Galena." 
 
 COL. Pale purplish gray. With galena or silver, pale purplish gray; 
 
 with coloradoite, somewhat bluer. 
 
 HARD. Low. SURF. Smooth but with triangular H. ? 
 
 cleavage pits like galena. 
 
 CHEM. 1. HNOs. Bright iridescent. 2. KCN . 3. HC1. Slowly 
 
 brown, faint. Fumes tarnish bright iridescent. 4. Aq. Reg. In- 
 stantly tarnishes bright which quickly darkens to deep blue; rubs 
 clean easily. 5. FeCl 2 . Slowly iridescent, rubs off clean. 6. KOH 
 
 DIFF.' Col. Surf. 
 
 NOTE. Reactions may be modified by the presence of calcite, or 
 native silver and niccolite, in the specimens tested. 
 
 PLENARGYRITE (soft) ? 
 
 COL. Bluish white. With galena, pale bluish white. 
 
 HARD. Low. SURF. Smooth. H < plenargyrite. 
 
 CHEM. 1. HNOa. Instantly iridescent, persistent. 2. KCN . 3. 
 
 HC1. Darkened and etched; fumes tarnish. Rubs clean easily. 4. 
 
 Aq. Reg. Instantly effervesces; turns iridescent, then black. Rubs 
 
 black and rough. 5. FeCls. Slowly dark brown, iridescent. Rubs 
 
 clean easily. 6. KOH . 
 
 DIFF. Chem. 3, 6. 
 
 NOTE. Occurs with plenargyrite exactly the same as "schap- 
 bachite" (soft), with schapbachite. 
 
 SCHAPBACHITE " (soft) ? 
 
 U4 COL. Bluish white. With galena, bluish white? 
 
 f^ HARD. Low. SURF. Smooth. H. < schapbachite. 
 
 JN CHEM. 1. HNO 3 . Instantly blackens, persistent. 2. KCN . 3. 
 
 I^j HC1. Instantly darkened and etched. Rubs clean. 4. Aq. Reg. In- 
 
 N. stantly blackens, persistent. 5. FeCls. Rather slowly brown, then 
 
 ^ bright and iridescent. Rubs clean easily. 6. KOH. Slowly brown. 
 
 Rubs clean easily. 
 |g DIFF. Chem. 3, 6. 
 
 I 
 
 hj 
 
 QQ COLORADOITE. See page 106. 
 
 | 
 
 I 
 
RAY. 
 
 KCN 
 
 CUPRITE Cu 2 O 
 
 COL. White. With galena, decidedly bluish white; with proustite 
 the same color. Transparent deep red by oblique light. 
 
 HARD. Medium. SURF. Shiny but usually pitted. H. 3.5-4> cc. 
 
 CHEM. 1. HNOs. Instantly plated with metallic copper, which blackens 
 and appears to dissolve immediately, with effervescence. On wash- 
 ing off and drying without rubbing, a film of copper is seen on the 
 surface, pink by oblique light. Rubs off easily, leaving a brilliant 
 iridescent surface on some grains, and some blackened. Fumes 
 tarnish iridescent. 2. HNOs cone. Effervesces, blackens and dis- 
 solves. 3. KCN. Quickly etches and develops a "cleavage" or 
 crystal structure (?) . 4. HC1. Instantly blackens and is coated with 
 white (seen by oblique light); rubs off. Fumes tarnish brilliant 
 iridescent. 5. HC1 cone. Same as HC1. 6. Aq. Reg. Same as HC1. 
 
 7. FeCl 3 . Rather quickly persistent dark iridescent. 8. KOH . 9. 
 
 NaOH . 10. (NH 4 )2S X . Quickly blackens and turns iridescent; 
 
 shows rough solution surface on rubbing. 
 
 DIFF. Col. Chem. 1 and 4. 
 
 NOTE. Practically always carries intermixed native copper. 
 
 STROMEYERITE (AgCu) 2 S 
 
 COL. White. With galena, bluish grayish white; with chalcocite, 
 purplish. 
 
 HARD. Low (very low). SURF. Smooth or "ragged." H. 2.5-3 < cc. 
 
 CHEM. 1. HNOs. Darkened slightly, and etched, developing a cleav- 
 age on some grains. Fumes tarnish brown, some grains more than 
 others. Tarnish washes off. 2. KCN. Quickly brown, dries darker, 
 and rubs off easily, leaving a clean, faintly creamy white, surface. 
 
 3. HC1 . Fumes slowly form a narrow tarnish ring around the drop. 
 
 Rubs off. 4. HC1 cone. Instantly dark and rough. Fumes tarnish 
 bright iridescent. Rubs off hard, leaving a roughened surface. 5. 
 Aq. Reg. Quickly speckled with black, rubs off to show slight rough- 
 ening (?). 6. FeCls. Instantly bright iridescent, showing structure. 
 Rubs easily to pale blues, and white, with a shallow solution pit. 7. 
 KOH . 
 
 DIFF. Hard. Col. Chem. 1. 
 
 CHALCOCITE See page 107. 
 
 09 
 
 J 
 
 POLYARGYRITE See page 114. 22 
 
 E I 
 
 BROGNIARDITE See page 110. 
 
 3 
 
 
 
 117 D 
 
WHITE 
 
 HARDNESS Low 
 
 CREAMY WHITE 
 
 SAME AS SILVER, OB WHITER 
 
 FeCls 
 
 s 
 
 I 
 
 I 
 
 No Eflf. Aq. Reg. 
 
 (HESSITE ?) ? 
 
 COL. White. With galena, pale creamy white; with silver, same. 
 
 HARD. Low. SURF. Smooth. H. 2-3 < gn. 
 
 CHEM. 1. HNOs. Instantly blackens with effervescence; rubs to gray, 
 and with continued rubbing to white again, with roughened surface. 
 2. KCN - ? 3. HC1 - . 4. Aq. Reg. - . 5. FeCls. Slowly bright 
 iridescent, persistent. 6. KOH - . 7. NaOH - . 8. (NH 4 ) 2 S X . 
 Quickly light iridescent; rubs off easily. 9. Iodine. Fumes, in- 
 stantly brilliant colors, rub off easily. Liquid, gray iridescent or 
 yellow, persistent. 
 
 DIFF. Surf. Chem. 1, 4. 
 
 NOTE. Differs in properties from crystallized hessite from Felso- 
 banya, Hungary. (See page 138.) 
 
 SILVER Ag 
 
 COL. White. With galena, pale creamy white. 
 
 HARD. Low. SURF. Metallic, smooth. H. 2.5-3. 
 
 CHEM. 1. HNOs. Blackens quickly, due to the formation of a very 
 rough solution surface, often showing crystalline etch figures. 2. 
 KCN - . 3. HC1 - . Fumes tarnish white, washes off. 4. HC1 
 cone. same. 5. Aq. Reg. Tarnishes quickly yellow, red, blue, bril- 
 liant colors, persistent. 6. FeCls. Quickly bright iridescent, per- 
 sistent. 7. KOH - . 8. (NH 4 ) 2 Sx - . Fumes tarnish brownish. 
 9. NH 4 OH - . 10. Iodine. White coating, rubs off bright iridescent. 
 
 DIFF. Col. Surf. Chem. 1, 5. 
 
 ALTAITE See page 128. 
 
 
 i 
 1 
 
 ^ 118 
 
 i 
 
GRAY. 
 
 
 t 
 
 Eff. Aq. 'Reg. 
 
 HUNTILITE AgaAs ? 
 
 COL. White. With galena, pale creamy white; with silver, practi- 
 cally same color; with algodonite (cream), nearly pure white. 
 
 HARD. Medium. SURF. Smooth. 
 
 CHEM. 1. HNOs. Instantly blackens, with vigorous effervescence; 
 forms very rough surface. 2. KCN. Slowly brown, then black. 
 
 Parts very resistant; rubs clean to show solution pits. 3. HC1 . 
 
 Fumes tarnish deep colored, persistent. 4. Aq. Reg. Instantly iri- 
 descent; effervesces, turns bright brown; rubs to bright iridescent, 
 persistent. 5. FeCls. Instantly iridescent, persistent. 6. KOH . 
 
 DIFF. Chem. 2. 
 
 NOTE. Only specimen available is much altered, to pale yellowish 
 gray mineral in dendritic veinlets. 
 
 
 
 1 
 
 (0 
 
 
 
 <0 
 
 u 
 
 S 
 
 CO 
 
 I 3 
 1 
 
 ! 
 
 119 
 
WHITE 
 
 HARDNESS Low 
 CREAMY WHITE 
 SAME AS SILVER, OR W: 
 FeCl* NEQ. 
 
 KOH Neg. 
 
 (MATILDITE ?) ? 
 
 COL. White. With galena, faint creamy white, like silver; with 
 
 silver, practically pure white. 
 j** HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs. Slowly bright yellowish brown; rubs to roughened 
 
 surface. 2. KCN . 3. HC1 . 4. HC1 5 cone. . 5. Aq. 
 
 Reg. Tarnishes and blackens quickly; rubs to rough, dark surface. 
 
 UJ 6. FeCU . 7. KOH . 
 
 ^ DIFF. Chem. 1, 4. 
 
 Ejj NOTE. Differs from true matildite, see page 140. 
 
 GUANAJUATITE Bi 2 Se 
 
 ^ COL. White. With galena, pale creamy white; with silver, practi- 
 
 ta cally white. Shows intergrowth of white and pale creamy gray 
 
 ^ (orientation different ?). 
 
 ^* HARD. Low. SURF. Smooth. H. 2.5-3.5. 
 
 Q> CHEM. 1. HNOa. Rapidly brilliant iridescent; rubs clean easily leaving 
 
 ZJj rough surface, white portions little touched. 2. KCN . 3. 
 
 y* HC1 . 4. HC1 cone. . 5. Aq. Reg. White untouched; grayer 
 
 O part instantly iridescent, with vigorous effervescence, then orange 
 
 yellow (?) coating formed, persistent, with rough surface. 6. 
 
 FeCl 3 . 7. KOH . 
 
 DIFF. Chem. 1, 4. 
 
 CHIVIATITE Pb 2 Bi 6 Su 
 
 rr> COL. Creamy white. With galena, pale creamy white; with silver, 
 
 faintly grayish white. 
 HARD. Low. SURF. Smooth. 
 
 s*J CHEM. 1. HNOs. Slowly tarnishes iridescent with slow effervescence. 
 
 I^i At last dark grayish. Thinly coated with white. Rubs clean easily, 
 
 showing slightly roughened surface. 2. KCN . 3. HC1 . 4. 
 
 Aq. Reg. Quickly brown, with vigorous effervescence. Coated with 
 
 ^ white. Rubs clean easily, showing a pitted surface. 5. FeCls . 
 
 El 6. KOH . 
 
 C/5 DIFF. Chem. 1. 
 
 a 
 
 BISMUTHINITE See page 130. 
 GALENOBISMUTITE See page 130. 
 
 I 
 
 I 
 
 ^ * 
 
 i 
 
 120 
 
GRAY. 
 
 KOH 
 
 WITTICHENITE 
 
 COL. White. With galena, creamy white; with silver, practically 
 same. 
 
 HARD. Low. SURF. Smooth. H. 3.5. 
 
 CHEM. 1. HNOs. Turns faintly yellowish, persistent, when washed off. 
 
 Fumes tarnish slowly. 2. KCN . 3. HC1 cone. . 4. Aq. Reg. 
 
 Rather quickly bright brown with slow effervescence. Fumes in- 
 stantly tarnish brown. Rubs clean rather easily. 5. FeCla . 6. 
 
 KOH. Slowly faint brown, rubs clean. 
 
 DIFF. Chem. 1, 4. 
 
 121 
 

 WHITE 
 
 HABDNESS Low 
 CREAMY WHITE 
 DARKER THAN SILVER 
 HNO, 
 FeCls NEQ. 
 
 COSALITE Pb 2 Bi 2 Ss 
 
 COL. White. With galena, creamy white; with silver, creamy white. 
 Mixture of creamy white and pale gray needles, due possibly to 
 difference in orientation of individuals. 
 
 HARD. Low. SURF. Smooth. H. 2.5-3. 
 
 CHEM. 1. HNOs. Creamy part instantly blackened, with effervescence; 
 
 gray hardly touched. 2. KCN . 3. HC1. Slowly faint yellowish, 
 
 rubs clean easily. 4. Aq. Reg. Instantly effervesces and tarnishes 
 iridescent, then blackens; fumes tarnish bright brown; rubs to gray 
 
 rough surface. 5. FeCl3 . 6. KOH. Rather quickly bright brown, 
 
 Q> .then iridescent. 
 
 DIFF. Chem. 1, 6. 
 
 Jj^ 
 
 JC EMPLECTITE CuBiS 2 
 
 ^ COL. White. With galena, decidedly creamy (brownish); with 
 
 . silver, pale brownish cream. 
 
 >* HARD. Low. SURF. Smooth. H. 2. 
 
 ]2J CHEM. 1. HNOs. Rather slowly light brown, with slight effervescence. 
 
 Fumes tarnish slightly. Rubs clean. 2. KCN . 3. HC1 . 4. 
 
 Aq. Reg. Rapidly blackens, with effervescence. Rubs to gray, with 
 
 U^ rough solution surface. Fumes tarnish yellowish brown. 5. 
 ^ FeCls . 6. KOH. Same as HNO 3 , but more slowly. 7. (NH^Sx 
 
 >^ DIFF. Chem. 1, 6. 
 
 METACINNABARITE HgS 
 
 COL. White. With galena, pale creamy and faint purple; with 
 
 silver, same as with galena. Intergrowth of pale blue (cinnabar ?) 
 
 and pinkish purple with creamy white. 
 U} HARD. Low. SURF. Smooth. H. 3. 
 
 t^ CHEM. 1. HNOs. Very slowly faintly yellowish. 2. KCN . 3. 
 
 N*, HC1 cone. Same as HNO 3 . 4. Aq. Reg. Quickly blackens, with 
 
 effervescence, leaving very rough surface. 5. FeCl 3 . 6. KOH. 
 
 Same as HNO 3 . 
 l DIFF. Chem. 1. 
 
 C/3 SYLVANITE AuAgTez 
 
 I^J COL. White. With galena, decided pale creamy white; with silver, 
 
 O pale cream. 
 
 i^ HARD. Low. SURF. Smooth. H. 1.5-2. 
 
 QQ CHEM. 1. HNOs. Instantly bright brown, iridescent around edges, per- 
 sistent; develops cleavage. 2. KCN . 3. HC1 . 4. Aq. Reg. 
 
 -^? Slowly effervesces, tarnishing, and dissolving where bubbles start. 
 
 Q Rubs clean to show pits. Fumes tarnish. With alabandite, in- 
 
 ^ stantly effervesces and etches, brown, persistent. 5. FeCls . Or 
 
 Jjj occasionally very slowly faint brown (doubtful). 6. KOH . 
 
 DIFF. Chem. 1, 6. 
 
 8 
 S5 
 
 122 
 
GRAY. 
 
 5 
 | 
 
 FRANKEITE See page 110. 
 WITTICHENITE See page 121. 
 AIKINITE See page 101. 
 CHIVIATITE See page 120. 
 FREIESLEBENITE See page 134. 
 
 123 
 
 6 
 a 
 f) 
 
WHITE 
 
 HARDNESS Low 
 
 CREAMY WHITE 
 
 DARKER THAN SILVER 
 
 HNOa 
 
 FeCla 
 
 HC1 Neg. 
 
 MELONITE 
 
 COL. Cream. With galena, decidedly creamy; with silver, de- 
 cidedly creamy. 
 
 HARD. Low. SURF. Smooth. H. 1-2 > gold. 
 
 CHEM. 1. HNOs. Instantly effervesces and blackens; rubs to irides- 
 cent and gray; showing some parts not discolored. 2. KCN . 3. 
 
 HC1 . 4. Aq. Reg. . 5. FeCls. Slowly darkens to light brown, 
 
 rubs to roughened surface. 6. KOH . 7. NaOH . 8. 
 
 (NH<) 2 S X . 
 
 DIFF. Chem. 1, 4 
 
 CALAVERITE AgAuTej 
 
 COL. Creamy white. With galena, decidedly deep cream color; with 
 silver, very pale cream; with melonite, very close, nearly the same. 
 
 HARD. Low. SURF. Smooth. H. 2.5. 
 
 CHEM. 1. HNOs. Quickly bright brown with slow effervescence; rubs 
 to light brown with iridescent edges. Develops delicate cleavage in 
 
 crystals. 2. KCN . 3. HC1 . 4. Aq. Reg. Effervesces and 
 
 slowly tarnishes green. 5. FeCls. Slowly brown, then bright irides- 
 cent; rubs clean to show solution pit. 6. KOH. Slowly tarnished 
 brownish; rubs off to pale yellow. 7. NaOH ? " 
 
 DIFF. Chem. 1, 4. 
 
 NOTE. Krennerite is the same as calaverite. 
 
 KALGOORLITE HgAu 2 Ag 6 Te ? 
 
 COL. White. With galena, pale creamy brown ; with silver, dull pale 
 
 creamy gray; with calaverite, decidedly paler creamy (gray). 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs. Very slowly faint brown. 2. KCN . 3. HC1 . 
 
 4. Aq. Reg. Instantly effervesces and turns iridescent, at last bril- 
 liant, with a persistent white coating. Covered with minute round 
 *^ pits formed by etching. 5. FeCls. Rapidly brilliant iridescent, per- 
 
 ^ sistent. 6. KOH . 
 
 C/} DIFF. Col. Chem. 1, 5. 
 
 *4 SYLVANITE ? See page 122. 
 
 Q ARSENIC See page 136. 
 
 ft5 HESSITE See page 138. 
 
 COPPER See page 67. 
 
 !5 TAPALPAITE See page 125. 
 
 PETZITE See page 137. 
 
 124 
 
 i 
 
GRAY. 
 
 HCl 
 
 DOMEYKTTE (Mixture) ' CtiaAs (Sb)? 
 
 x COL. White. With galena, pale yellowigh creamy gray and very pale purple; 
 
 with silver, same as with galena. 
 
 HARD. Low or medium. SURF. Smooth. H. 3-3.5. 
 
 CHEM. 1. HNOs. Effervesces and blackens immediately, dissolves. 2. HNOs cone. 
 Same. 3. KCN. - . Purple portion turned pinkish. 4. HCl. Develops struc- 
 ture in white part; purple - . 5. HCl Cone. Same. 6. Aq. Reg. Instantly 
 effervesces and etches, developing a structure. Fumes tarnish iridescent. 
 Rubs clean easily. 7. Feds- Instantly dark iridescent; rubs to clean rough 
 surface. 8. KOH. Tarnishes rapidly to brilliant iridescent; rubs clean easily; 
 purple tarnishes first. 9. (NH4) 2 S X . Quickly darkens, dissolves white quicker 
 than purple. 10. NH4OH. Purple, bright yellowish brown, white hardly 
 touched. 11. KiFe(CN) 8 . Purple turns black, white turns brown, persistent. 
 12. K3Fe(CN) 6 . Same as 11. 
 DIFF. Chem. 1, 2. 
 
 NOTE. Only one specimen showed this mixture. Three others show the 
 same components as algodonite. 
 
 BISMUTH Bi 
 
 COL. Creamy white, tarnishing very rapidly pale yellow, persistent. With 
 galena, pinkish creamy white; with silver, pale pinkish creamy white, not so 
 yellow as with galena. 
 
 HARD. Low. SURF. Metallic, smooth. H. 2-2.5 < silver. 
 
 CHEM. 1. HNOa. Instantly blackens with vigorous effervescence; rubs to light 
 gray coating. 2. KCN - . 3. HCl. Slowly darkens, persistent, and dissolves. 
 4. Aq. Reg. Rapidly blackens with effervescence; dissolved deeply. 5. FeClj. 
 Instantly attacked, differentially, some grains hardly touched, others dark- 
 ened. 6. KOH - . 
 DIFF. Col. Chem. 1, 2. 
 
 NOTE. The friction of rubbing lightly on a rouge block tarnishes bismuth 
 yellow. This yellow is very distinctive for bismuth. If dried without 
 rubbing, the true color is preserved. 
 
 DYSCRASITE AgsSb, Ag 9 Sb, etc. 
 
 COL. White. With galena, pale creamy white; with silver, pale creamy white; 
 with argentite, white. 
 
 HARD. Low. SURF. Smooth. H. 3.5-4 <C niccolite. 
 
 CHEM. 1. HNOs. Tarnishes and rapidly develops " felted " acicular structure or 
 coarser intergrowth, differentially etched. 2. KCN. Develops brownish needles 
 or patches rather slowly, and faint, on white ground. 3. HCl. About the same as 
 HNO 3 , not so good. 4. HCl cone. Same as HCl. 5. Aq. Reg. Sometimes with 
 effervescence. Instantly iridescent, then pale brownish, rubs off to brilliant 
 iridescent colors. 6. FeCl 3 . Instantly brilliant iridescent. Differential tarnish, 
 part turned yellowish, part with needles brilliant, persistent. 7. KOH - . 8. 
 (NH 4 ) 2 S X . Quickly develops " felted " structure, in bright brown, then darkens 
 to very dark green, which rubs off easily, showing structure again. 9. NHiOH 
 
 DIFF. Chem. 1, 2. 
 TAPALPAITE. 3 Ag 2 (S,Te).Bi 2 (S, Te) 3 ? Mixture? 
 
 Jj 
 
 ^ 
 
 COL. Creamy white. (Shows intergrowth of gray and creamy white. Only 
 creamy part of specimen is considered here. For gray 'part, see page 107.) 
 With galena, creamy white; with silver, slightly creamier white. 
 
 HARD. Low. SURF. Smooth. (/) 
 
 CHEM. 1. HNO 3 . Instantly blackens with effervescence; coated with white (?); 
 
 fumes tarnish. Rubs to blackened, etched surface. 2. KCN . 3. HCl. m fj 
 
 Faint brown, fumes tarnish faintly. Rubs clean. 4. Aq. Reg. Effervesces and rt . 
 
 slowly turns grayish. Fumes tarnish slightly; rubs clean easily. 5. FeCla. V /* 
 
 Instantly iridescent, darkening. Rubs to gray, rough. 6. KOH - . TT. A 
 
 DIFF. Chem. 1,2,3. 
 
 CHILENITE ga ^ 
 
 COL. Creamy white. With galena, deep creamy white; with silver, slightly Q) V 
 
 creamier. yj 
 
 HARD. Low. SURF. Smooth. T* T 
 
 CHEM. 1. HNOs. Instantly effervesces and blackens. Dissolves; rubs clean, JJ ^ ~.~ 
 
 giving very rough surface. 2. KCN. Instantly yellowish brown; rubs clean 9 - \/4 
 
 . . . - 
 
 easily. 3. HCl. Instantly iridescent, then brown, shows roughened surface. fj 2 C/) 
 
 Rubs to persistent iridescent. 4. Aq. Reg. Like HCl, but more vigorous. 5. QJ 
 
 *+ 
 
 ^ t 
 
 Q; 
 
 . 
 
 FeCl 3 . Instantly brilliant, then darker, iridescent. Rubs to persistent irides- 
 
 cent gray. 6. KOH - . ^ ^ t 
 
 DIFF. Chem. 2, 3. 
 
 TEALLITE. See page 106. 
 
 125 
 
SH 
 
 I 
 
 1 
 
 3! 
 
 S 
 I 
 
 WHITE 
 
 HARDNESS Low 
 CREAMY WHITE 
 DARKER THAN SILVER 
 HNOs NEQ. 
 
 UNKNOWN (creamy, from Butte, Mont.) ? 
 
 COL. Creamy white. With galena, faintly creamy white; with 
 
 silver, faintly grayish white. 
 
 HARD. Low. SURF. Smooth. H. = bn. 
 
 CHEM. 1. HNO 3 - . 2. KCN. Slowly pale purple tarnish; rubs clean 
 easily. 3. HC1 - . 4. Aq. Reg. - . 5. FeCb - . 6. KOH - . 
 DIPT. Chem. 1, 2. 
 
 NOTE. Probably carries bismuth. 
 
 8 
 
 ft SULVANITE See page 72. 
 
 I 
 
 . CHALMERSITE See page 72. 
 
 ^- BERTHIERITE See page 103. 
 
 I 
 
 GOLD (var. electrum) See page 62. 
 
 S: 126 
 
 I 
 
GRAY 
 
 I 
 
 (0 
 
 I 
 
 UJ 
 
 z 
 
 Q 
 
 c* 
 
 127 
 
s 
 
 I 
 
 WHITE 
 
 HARDNESS Low 
 GALENA WHITE 
 PURE WHITE 
 HC1 
 
 PbTe 
 
 With galena, pure white; 
 
 with silver, whiter than 
 
 I 
 
 ALTAITE 
 
 COL. White, 
 silver. 
 
 HARD. Low. SURF. Smooth. H. 3 +. 
 
 CHEM. 1. HNOa. Quickly brown with effervescence, develops little 
 crystallites ? (or crosses and treelike forms) in it. Rubs to gray, 
 
 showing etch figures better. 2. KCN . 3. HC1. Quickly bright 
 
 iridescent; rubs to grayish brown, develops cracking, and leaves 
 some uncolored patches. 4. Aq. Reg. Instantly bright iridescent 
 tarnish; dries pale, and rubs clean readily. 5. FeCls. Instantly 
 bright brown iridescent, persistent; rubs to gray and rough. 6. 
 
 KpH . 7. NaOH . 8. (NHOaS x . 9. Iodine, Tarnishes 
 
 bright yellowish, rubs clean easily. 
 
 DIFF. Chem. 1. 
 
 CLAUSTHALITE PbSe 
 
 COL. White. With galena, pure white; with silver, white with faint 
 bluish cast. 
 
 HARD. Low. SURF. Smooth. H. 2.5-3. 
 
 CHEM. 1. HNO 3 . Brick red coating forms instantly, which rubs off, 
 
 leaving a grayish brown stain. 2. KCN . 3. HC1. Slowly darkens, 
 
 brownish, rubs clean. 4. HC1 cone. Same. 5. Aq. Reg. Instantly 
 bright iridescent; rubs to greenish gray. 6. FeCls. Slowly darkens, 
 coated with mixed blue and yellow, yellowish by oblique light; per- 
 sistent. 7. KOH . 
 
 DIFF. Chem. 1. 
 
 H 
 
 I 
 
 I 
 
 Si 
 
 NAUMANNITE (Ag 2 Pb) Se 
 
 COL. White. With galena, pure white; with silver, white with 
 bluish cast. 
 
 HARD. Low. SURF. Smooth. H. 2.5. 
 
 CHEM. 1. HNOs. Instantly blackens with effervescence; leaves very 
 rough surface. 2. KCN . 3. HC1. Slowly bright brown irides- 
 cent. 4. Aq. Reg. Instantly iridescent, and blackens with efferves- 
 cence; rubs to gray. 5. FeCU. Slowly bright brown; rubs clean 
 easily and leaves very shallow solution pit. 6. KOH . 
 
 DIFF. Chem. 1. 
 
 a: 
 
 g 
 
 128 
 
GRAY 
 
 I 
 
 ! 
 
 uu 
 z 
 
 Q 
 
WHITE 
 
 HARDNESS Low 
 GALENA WHITE 
 PURE WHITE 
 HC1 NEQ. 
 
 ^ GALENOBISMUTITE PbBi 2 S4 
 
 W COL. White. Mixture (?) of silvery white and faintly yellowish 
 
 white, somewhat harder. With galena, mixture of slightly different 
 shades of creamy white; with silver, practically white. 
 . Occ. As blades or plates. 
 
 bO HARD. Low. SURF. Smooth. H. 3-4. 
 
 ^ CHEM. 1. HNOs. Instantly bright brown, then black. Washes off to 
 
 i^ show whiter portion black, and grayer part coated with orange 
 
 yellow. White more dissolved than other. 2. KCN . 3. 
 
 ?* HC1 . 4. Aq. Reg. . 5. FeCls . 6. KOH . 
 
 |j) DIFF. Chem. 1, 4. 
 
 Cq BISMUTHINITE Bi 2 S 3 
 
 ^ COL. White. With galena, whiter, and less bluish; with silver, pale 
 
 J*2 grayish white. Shows different colors along and across the cleavage. 
 
 !^J Occ. As blades and plates. 
 
 ^ HARD. Low. SURF. Smooth. H. 2. 
 
 ^ CHEM. 1. HNOs. Blackens immediately, leaving a rough solution sur- 
 
 face. 2. KCN . 3. HC1 . 4. HC1 cone. Tarnishes iridescent. 
 
 ^ 5. Aq. Reg. Eff ervesces slightly and slowly turns brown; rubs clean f 
 ^ showing roughened surface. 6. FeCls . 7. KOH . 8. NaOH 
 
 . 9. (NH) 2 Sx . 10. NH 4 OH . 
 
 ^ DIFF. Chem. 1, 5. 
 
 i 
 
 O EUCAIRITE Cu 2 Se.Ag 2 Se 
 
 COL. White. With galena, bright white, makes galena look yellow- 
 ish; with silver, bright white. 
 
 HARD. Low. SURF. Smooth. H. 2.5. 
 CHEM. 1. HNOs. Unchanged for a moment, then rapidly tarnished and 
 blackened. Coated with orange yellow or reddish. Rubs to green- 
 ish gray. 2. KCN . 3. HC1 . 4. Aq. Reg. Instantly effer- 
 vesces, then stops, and turns slowly faint brown. Rubs clean easily. 
 U4 Places where bubbles started marked by white coating. 5. FeCl 3 . 
 
 5^ Slowly very faint brown. 6. KOH . 
 
 J> DIFF. Chem. 1, 4, 5. 
 
 JC NOTE. Gives off selenium odor when ground on the coarse wheel. 
 
 > TELLURIUM Te 
 
 (/) COL. White. With galena, almost pure white; with silver, practi- 
 
 i*4 cally pure white; with altaite, very pale creamy white. 
 
 HARD. Low. SURF. Semi-metallic, smooth. H. 2-2.5. 
 
 CHEM. 1. HNOs. Instantly effervesces and blackens; rubs to dark 
 
 J2 gray, rough surface. 2. KCN . 3. HC1; . 4. Aq. Reg. Effer- 
 
 ^ vesces and turns brown, then black, forming white coating. Rubs 
 
 to rough and gray. 5. FeCls. Slowly iridescent, brilliant. Persis- 
 tent; shows solution surface. 6. KOH . 
 
 DIFF. Chem. 1, 6. 
 
 UNKNOWN (white, from Bisbee, Ariz.) ? 
 COL. White. With galena, pure white. 
 HARD. Low. SURF. Smooth. H. = gn. 
 
 CHEM. 1. HNO 3 . 2. KCN. Very slowly brown, then iridescent; 
 
 rubs clean easily. 3. HC1 . 4. Aq. Reg. Instantly iridescent, 
 
 JS then black;| rubs to roughened black surface. 5. FeCls. Quickly iri- 
 
 5S descent and blackens; rubs clean, showing roughened surface. 6. 
 
 j^ KOH. Rather quickly iridescent then black, persistent. 
 
 DIFF. Chem. 6. 
 
 5 
 
 5 130 
 
 1 
 
GRAY 
 
 LEHRBACHITE PbSe -f HgSe 
 
 COL. Pure white. With gajena, pure white. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 . 4. Aq. Reg. . 5. 
 
 FeCls . (Possibly FeCls browns slightly, but observations were 
 
 made in presence of soluble gangue, so reactions may be modified.) 
 6. KOH . 
 
 DIFF. Chem. 1. 
 
 BERZELIANITE Cu 2 Se 
 
 COL. Pure white. With galena, pure white. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOa. Untouched an instant, then quickly bright irides- 
 cent, with a little reddish coating. Rubs to greenish gray tarnish. 
 
 2. KCN . 3. HC1 . 4. Aq. Reg. Quickly brown, then bright 
 
 iridescent. Rubs to pale gray. 5. FeCla. Rather soon light brown 
 (seen on rinsing off reagent). Rubs clean easily. 6. KOH . 
 
 DIFF. Chem. 1, 4, 5. 
 
 ANTIMONIAL BISMUTHINITE Bi 2 (S,Sb) 3 
 
 COL. White. With galena, pure white, or with a faint creamy tinge. 
 Occ. Plates, usually thin, or blades, appearing as needles in the 
 
 section. 
 
 HARD. Low. SURF. Smooth. H.<C en = gn. 
 
 CHEM. 1. HKOs. Slowly tarnishes, then blackens, finally thinly coated 
 
 with white. Rubs off gray, and rough. 2. KCN . 3. HC1 . 
 
 4. HC1 cone. . 5. Aq. Reg. Quickly bright brown, then black. 
 
 Rubs to persistent rough, dark surface, showing much solution. 6. 
 
 FeCk . 7. KOH . 
 
 DIFF. Occ. Chem. 1, 5. 
 
 MATILDITE See page 140. 
 
 * * 
 
 <0 
 
 : s 
 
 
 
 s 
 
 D 
 
 131 
 
 fi 
 
 (0 
 
 (0 
 
S WHITE 
 
 S^ HARDNESS Low 
 
 GALENA WHITE 
 SAME AS GALENA OB DABKEB 
 
 ^ HN0 3 
 
 KCN NEQ. 
 
 < HC1 
 
 3 
 
 QQ 
 
 I 
 
 FeCls Neg. 
 
 GEOCRONITE 
 
 COL. White. With galena, very slightly creamy, almost the same; 
 
 with silver, faintly bluish white. 
 
 HARD. Low. SURF. Smooth. - H. 2.5. 
 
 CHEM. 1. HNOs. Quickly tarnishes and blackens, with white coating; 
 
 rubs to iridescent gray, showing little "crystallites." 2. KCN . 
 
 3. HC1. Very slowly faint brown. 4. HC1 cone. Instantly bright 
 
 brown. 5. Aq. Reg. Rapidly tarnishes brilliant iridescent. 6. 
 
 FeCls . 7. KOH . 8. NaOH . 
 
 DIFF. Chem. 1, 2, 5, 6. 
 
 rr> 
 
 ^, MENEGHINITE 
 
 ]2J COL. White. With galena, faintly grayish (or creamy white) very 
 
 close. 
 HARD. Low. SURF. Smooth. H. = gn. 
 
 1^ CHEM. 1. HNOs. Untouched a moment, then very rapidly blackens. 
 
 (V Appears gray by oblique light. Rubs to gray surface, showing 
 
 smooth white crystallites, like geocronite. 2. KCN. - 3. HC1. 
 
 >* Slowly gray, some grains more than others. Fumes tarnish a bright 
 
 ring. Rubs off, leaving a shallow, grayish pit. 4. Aq. Reg. Turns 
 rather slowly iridescent. Fumes tarnish. Rubs to persistent iri- 
 descent. 5. FeCls - . 6. KOH. Very slowly colored blue or 
 reddish. 
 DIFF. Chem. 1,5,7. 
 
 SEMSEYITE Pb 7 Sb 6 Si 
 
 COL. White. With galena, very slightly grayish (creamy) white, 
 ^j almost same. Two faintly different colors observed, apparently due 
 
 to orientation. 
 ^ HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs. After a moment bright iridescent, quickly blacken- 
 
 j^ ing; coated thinly with white. Rubs off to show persistent gray, 
 
 j< slightly roughened surface. 2. KCN - . 3. HC1. Slowly very faint 
 
 brown. Fumes tarnish narrow ring, brightly. Rubs clean easily. 
 
 ^j 4. Aq. Reg. Instantly iridescent, then blackens, with effervescence. 
 
 J Fumes tarnish brilliant. Rubs to faint gray, roughened surface. 
 
 5. FeCla - . 6. KOH - . 
 DIFF. Chem. 1. 
 
 < 
 I 
 
 ZINKENITE See page 111. 
 PLAGIONITE See page 135. 
 JAMESOKITE See page 111. 
 
GRAY 
 
 FeCL 
 
 LILLIANITE , Pb 3 Bi 2 S 
 
 COL. White. With galena, same. Shows cubic cleavage by incip- 
 ient alteration. 
 
 HARD. Low. "SuRF. Smooth. H. = gn? 
 
 CHEM. 1. HNO 3 . Instantly iridescent. Ru bs clean and smooth easily. 
 
 2. KCN . 3. HC1. Slowly light brown (differential action on 
 
 different grains). Fumes tarnish bright. Rubs off rather easily, 
 
 smooth and clean. 4. Aq. Reg. Instantly dark brown, then nearly 
 
 black, coated with white. Fumes tarnish a narrow rim, bright. 
 
 Rubs clean and smooth easily. 5. FeCls. Slowly bright iridescent. 
 
 Rubs smooth and clean easily. 6. KOH . 
 
 DIFF. Surf. Chem. 1. 
 
 GALENA PbS 
 
 COL. White. With silver, bluish white. 
 
 HARD. Low. SURF. Smooth, but usually H. 2.5-2.75. 3C 
 
 shows triangularlpits. 
 CHEM. 1. HNOs. Blackens quickly with a dark, persistent coating. 2. 
 
 KCN . 3. HC1. Slowly faint brown. 4. HC1 cone. Quickly brown, 
 
 fumes tarnish. 5. Aq. Reg. Instantly blackens. 6. FeCls. Bright, 
 
 iridescent, persistent. 7. KOH . 8. (NH 4 ) 2 Sx . 9. NH 4 OH 
 
 DIFF.' Surf. Chem. 1. 
 
 NOTE. A specimen of galena from Central City, Col., intergrown 
 with tellurides and native tellurium, with HNOs is unchanged 
 for an instant, then turned dark brown; rubs clean to show 
 smooth solution pit, cream colored. 
 
 Galena with intergrown pure white or creamy minerals, such 
 as selenides or tellurides is apt to appear very purple, and care 
 must be taken not to confuse it with purple "galena," which is 
 really purplish, as is shown by comparing it with ordinary galena. 
 
 STEINMANNITE PbS (As, Sb) (var. galena) 
 
 COL. White. With galena, same. 
 
 HARD. Low. SURF. Smooth, with triangular cleavage pits. H = gn? 
 CHEM. 1. HNOs. Instantly iridescent, then blackens with efferves- 
 cence; coated with white. Rubs to gray rough surface. 2. KCN 
 
 . 3. HC1. Rather quickly blackens, and is coated with white. 
 
 Rubs off to show rough gray surface, with spots which rub clean and 
 
 smooth. 4. Aq. Reg. Instantly iridescent, then black. Coated 
 
 thinly with white; rubs clean easily and shows slightly roughened 
 
 surface. 5. FeCls. Slowly bright iridescent. Rubs clean and smooth 
 
 easily. 6. KOH . 
 
 DIFF. Surf. Chem. 1. 
 
 TETRAD YMITE ? Bi 2 (TeS) 3 
 
 COL. White. With galena, very slightly yellowish or grayish, prac- . 
 tically the same; with silver, pale, decidedly purplish grayish white; 
 
 with bismuthinite, decidedly purplish gray. H t% 
 
 HARD. Low. SURF. Smooth. H. 1.5-2. {J * 
 
 CHEM. 1. HNOs. Rather rapidly deep brown, then black fumes tarnish M ^ 
 
 brownish. Rubs to rough, light gray surface. 2. KCN . 3. J2 
 
 HC1. Slowly bright brown; rubs to uneven pale brown. 4. HC1 ^ 
 
 cone. Quickly brown, then iridescent. 5. Aq. Reg. Slowly brown, ^ 
 
 somewhat persistent. 6. FeCls. Slowly faint brown, persistent. 
 
 Rubs clean, shows solution surface. 7. KOH . 8. (NH4) 2 Sx. 
 
 Darkens to deep grayish brown, rubs clean. <fl 
 
 Rubs clean, shows solution surface. 7. KOH . 8. (NH4) 2 Sx. C/) 
 
 Darkens to deep grayish brown, rubs clean. <fl r/\ 
 
 DIFF. Surf. Chem. 1,2. fi 
 
 NOTE. Shows galena (?) cleavage, and may possibly be only ^ 
 
 galena carrying tellurium. Intergrown with a little of a creamy ~* 
 
 mineral which might be the true tetradymite. e* Q 
 
 * I 
 
 133 
 
 6 
 
WHITE 
 
 HARDNESS Low 
 
 GALENA WHITE 
 
 SAME AS GALENA OR DAI 
 
 HNOa 
 
 KCN NEQ. 
 
 HQ NBQ. 
 
 FeCl NEQ. 
 
 No Eff. HNOs 
 NAGYAGITE Au 2 Pb 10 Sb 2 Te 6 S 15 (Hintze) 
 
 COL. White. With galena, very pale grayish white; nearly same; with silver, 
 
 pale bluish grayish white. 
 
 HARD. Low. SURF. Smooth. H. 1-1.5. 
 
 CHEM. 1. HNO 3 . After a short time suddenly iridescent, bright; rubs to dark 
 
 gray. 2. KCN . 3. HC1 . 4. Aq. Reg. Quickly iridescent, then black. 
 
 5. FeCl 3 . 6. KOH . 
 
 DIFF. Chem. 1. 
 
 FREIESLEBENITE (PbAg^Sb^Sn 
 
 COL. White. With galena, pale creamy white; with silver, pale (brownish) 
 
 cream. 
 
 HARD. Low. SURF. Smooth. H. 2-f. 
 
 CHEM. 1. HNO 3 . Blackened and roughened. 2. KCN . 3. HC1 . 4. Aq. 
 
 Reg. Instantly effervesces then turns bright brown iridescent, rubs clean easily. 
 
 5. FeCl 3 . 6. KOH . 7. NaOH . 8. 
 
 DIFF. Chem. 1, 6. 
 
 GUITERMANITE Pb3As 2 S 6 
 
 COL. White. With galena, very close, slightly grayish (?). 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNO. Instantly bright iridescent. Rubs clean, leaving roughened 
 
 surface. 2. KCN . 3. HC1 . 4. Aq. Reg. Instantly iridescent, with 
 
 effervescence; then darkens. Rubs to gray roughened surface. 5 FeCl . 
 
 6. KOH . 
 DIFF. Chem. 1, 4. 
 
 BEEGERITE Pb,,Bi 2 S 9 
 
 COL. White. With galena, very pale creamy white; with silver, decidedly 
 
 grayish white. 
 
 HARD. Low. SURF. Smooth. H. < cp. 
 
 CHEM. 1. HNO 3 . Parts instantly, parts slowly, iridescent. Fumes tarnish 
 
 brown. Rubs easily to pale gray. 2. KCN . 3. HC1 . 4. Aq. Reg. 
 
 Instantly effervesces slowly, and turns bright iridescent, then black. Fumea 
 tarnish bright. Parts coated with white. Rubs to iridescent gray. 5. 
 
 UJ FeCl 3 . 6. KOH . 
 
 Kj DIFF. Chem. 1, 4. 
 
 JORDANITE ? PbiAszS: ? 
 
 COL. White. With galena, very pale grayish white, very close; with tetrahe- 
 
 drite, practically white. 
 
 HARD. Low. SURF. Smooth. H. < si. 
 CHEM. 1. HNO 3 . Untouched a moment, then slowly light gray. Rubs very pale 
 gray, slightly rough. 2. KCN . 3. HC1 . 4. Aq. Reg. Instantly irides- 
 cent, effervesces and blackens. Rubs to gray roughened surface. 5. FeCl . 
 
 6. KOH . 
 
 j\ DIFF. Chem. 1. 
 
 L^ ANDORITE Pb 2 Ag 2 Sb 6 S 9 
 
 JL COL. White. With galena, very pale (creamy) grayish white; with silver, dull 
 
 SN, grayish white; with tetrahedrite, much lighter, grayish white. 
 
 M^ HARD. Low. SURF. Smooth. H. = 3-3.5? 
 
 J^. CHEM. 1. HNO 3 . Rather slowly iridescent, rubs clean easily. 2. KCN . 3. 
 
 ^ HC1 . 4. Aq. Reg. Slowly brown, then brilliant iridescent, with increasing 
 
 effervescence. Fumes tarnish brilliant ring quickly. White coating formed. 
 
 S Rubs off to show deeply etched surface. 5. FeCl 3 . 6. KOH. Slowly pale 
 
 *^< brown, darkening to bluish iridescent. Rubs clean easily. 
 
 C/} DIFF. Chem. 4, 6. 
 
 ^J EPIBOULANGERITE Pb 3 Sb 2 S 8 
 
 ^ COL. Galena white. With galena, practically the same. Faintly greenish gray. 
 
 i^ HARD. Low. SURF. Smooth. H. 
 
 ^* CHEM. 1. HNO 3 . Untouched a moment, then blackens, and is coated with white. 
 
 **N Rubs off to show gray surface studded with little white crystals which have 
 
 p ^ rubbed clean. 2. KCN . 3. HC1 . Fumes tarnish slightly. 4. Aq. Reg. 
 
 fS y Instantly effervesces and blackens. Fumes tarnish bright iridescent. Rubs to 
 
 : !^J gray, etched surface. 5. FeCl 3 . 6. KOH . 
 
 ^ DIFF. Chem. 1. 
 
 Kj UNKNOWN (near andorite) ? 
 
 COL. White. With galena, very pale (greenish) grayish white, rather close. 
 HARD. Low. SURF. Smooth. H. gn. 
 
 CHEM. 1. HNO 3 . Very slowly brown and iridescent; rubs to faint gray. 2. 
 
 KCN . 3. HC1 . 4. HC1 cone. . Fumes tarnish light brown. 5. Aq. 
 
 IJj Reg. Instantly effervesces and turns iridescent, darkens, with little or no white 
 
 l^ coating. Fumes tarnish brilliant iridescent; rubs to gray roughened surface, 
 
 ^ fumes rub clean. 6. KOH . 7. FeCl 3 . 
 
 s^J DIFF. Chem. 6. 
 
 t^ NOTE. Very close to andorite in properties. 
 
 BISMUTHINITE See page 130. 
 
 LENGENBACHITE See page 141. 
 
 *^ BAUMHAUERITE See page 108. 
 
 j JAMESONITE See page 111. 
 
 < 134 
 
GRAY 
 
 Eff. HNOs 
 
 BOULANGERITE ~Pb 3 Sb 2 S 
 
 COL. White. With galena, very pale grayish white, with silver, very 
 
 pale bluish grayish white. 
 
 HARD. Low. SURF. Smooth. H. 2.5-3. 
 
 CHEM. 1. HNOs. Rapidly blackens with effervescence. 2. KCN . 
 
 3. HC1 . 4. Aq. Reg. Same as HNO 3 but slower. 5. FeCl* . 
 
 6. KOH . 7. NaOH . 8. (NH 4 ) 2 S X . ^ 
 
 DIFF. Chem. 1. 
 
 DOGNACSKAITE Bi,Cu,S ? j 
 
 COL. White. With galena, pale creamy white; with silver, pale ^J 
 
 grayish white. Also shows some intergrowth of a bluish mineral, 
 
 same hardness. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs. Instantly effervesces and tarnishes iridescent, then 
 
 blackens. Coated with pale yellowish white. Fumes tarnish, rubs 
 
 to rough black. 2. KCN . 3. HC1 . 4. Aq. Reg. Instantly 
 
 effervesces and tarnishes brown. Fumes tarnish. Rubs clean 
 
 easily, showing slight solution pits where bubbles started. 5. 
 
 FeCls . 6. KOH . 
 
 DIFF. Chem. 1, 6. 
 
 HORSFORDITE Cu 6 Sb ? 
 
 COL. White. With galena, very pale creamy, almost same; with 
 silver, pale bluish or grayish white. 
 
 HARD. Low. SURF. Smooth. H. 4-5. 
 
 CHEM. 1. HNOs. Instantly blackens with slight effervescence; rubs to 
 light gray iridescent. 2. KCN . 3. HC1 . 4. Aq. Reg. In- 
 stantly etches; part brown, part little changed; rubs to pale gray. 
 
 Fumes tarnish bright. 5. FeCls . 6. KOH. Slowly faint brownish 
 
 and bluish; rubs faint. 
 
 DIFF. Chem. 1, 6. 
 
 PLAGIONITE PbsSbsSn 
 
 COL. White. With galena, very pale grayish white, very near. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs. Untouched a moment, then quickly dark iridescent, 
 
 with effervescence; finally black. Rubs to persistent gray. 2. 
 
 KCN . (Or very slowly faint brown?). 3. HC1 . Fumes tarnish 
 
 bright. 4. Aq, Reg. Instantly effervesces and tarnishes bright. 
 
 Fumes tarnish brilliant. Rubs clean easily. 5. FeCls . 6. KOH. 
 
 Slowly brown, then purple, then blue, iridescent. Washes to pale ( 
 
 blue. Rubs clean very easily. ^ 9) 
 
 DIFF. Chem. 1, 6 " 
 
 a 
 
 : s 
 
 CHIVIATITE See page 120. 
 
 2 
 
 i 
 
 135 0) 
 
 i 
 

 
 Vl WHITE 
 
 |S< HARDNESS Low 
 
 ^ GALENA WHITE 
 
 "^ SAME AS GALENA OB DARKER 
 
 ^ HNO 3 
 
 KCN NEQ. 
 < HC1 NEQ. 
 
 FeCU 
 
 ARSENIC AS 
 
 COL. White. With galena, faintly creamy white, almost the same; 
 
 with silver, very close, with a suggestion of gray. 
 HARD. Low. SURF. Smooth. H. 3.5. 
 
 CHEM. 1. HNOs. Instantly darkens, through brown to black, with slow 
 
 effervescence; rubs to bluish gray. 2. KCN . 3. HC1 . 4. 
 
 Aq. Reg. Turns slowly brown with effervescence; rubs off to show 
 fT> uneven solution surface. 5. FeCls. Quickly darkens, brownish, 
 
 WJ persistent. 6. KOH . 
 
 ^ DIFF. Chem. 5. 
 
 J^j NOTE. Gives off arsenic odor when ground on the coarse wheel. 
 
 UNKNOWN ("ALLOKLAS") ? 
 
 ^, COL. White. With galena, pale creamy white, rather close. 
 
 _ HARD. Low. SURF. Smooth. H. < cp. 
 
 ^ CHEM. 1. HNOs. Instantly effervesces and blackens; coated with 
 
 ^ white. Rubs to black etched surface. 2. KCN . 3. HC1 . 
 
 Q> 4. Aq. Reg. Instantly effervesces and tarnishes brown. Fumes 
 
 Zj tarnish bright brown. Rubs off to show grayish etched surface. 5. 
 
 p5 FeCls. Slowly very faint brown. 6. KOH . 
 
 O DIFF. Chem. 1, 5. 
 
 NOTE. This is a specimen labelled alloklas, but not agreeing with 
 the descriptions of alloclasite. 
 
 REZBANYITE Pb 4 BiioSi9 
 
 COL. White. With galena, very pale grayish white (two faintly dif- 
 r> ferent shades, probably due to different orientation). 
 
 HARD. Low. SURF. Smooth. H. = 2.5-3. 
 
 ^J CHEM. 1. HNOs. Instantly iridescent; fumes tarnish bright. Etched 
 
 s5J differentially, some grains more rapidly than others. Rubs to pale 
 
 ^ gray, etched surface. 2. KCN . 3. HC1 . 4. Aq. Reg. In- 
 
 ^ stantly effervesces and tarnishes iridescent. Fumes tarnish bright. 
 
 Rubs to pale gray etched surface. 5. FeCls. Slowly faint brown. 
 
 ^ 6. KOH . 
 
 ^ DIFF. Chem. 1, 5. 
 
 
 
 PLENARGYRITE (hard) AgBiS? (mixture) 
 
 ML COL. Shows intergrowth of creamy (hard) and bluish (soft) whites. 
 
 "^ With galena, very pale creamy (?) white; with silver, grayish white. 
 
 w c *- HARD. Low. SURF. Smooth. H. = 2.5? 
 
 O sj CHEM. 1. HNOs. Slowly iridescent. Rubs clean easily. 2. KCN . 
 
 J^ '"S 3. HC1 . 4. Aq. Reg. Quickly bright iridescent, then darker. 
 
 S Fumes brilliant iridescent. Rubs black and rough, showing deep 
 
 *N 1 solution. 5. FeCla. Very slowly brown. Rubs clean easily. 6. 
 
 KOH . 
 
 DIFF. Chem. 1, 4. 
 
 NOTE. Very like schapbachite in general appearance. 
 
 I 
 I 
 
 136 
 
GRAY 
 
 SCHAPBACHITE (hard) PbAgsBisSs (mixture) 
 
 COL. White. Mixture of creamy (?) (harder) and bluish (softer) 
 whites. With galena, pale creamy white. With silver, grayish 
 white. bo 
 
 HABD. Low. SURF. Smooth. H. < cp. 
 
 CHEM. 1. HNOs. Slowly brown; rubs clean. 2. KCN . 3. HC1 . JZj 
 
 4. Aq. Reg. Slowly pale brown, finally dark (like HNO 3 ). Rubs 
 clean. 5. FeCl 3 . Very slowly pale brown. Rubs clean. 6. KOH . 
 
 DIFF. Chem. 1,4. 
 
 NOTE. Very like plenargyrite in general appearance. 
 
 PETZITE (AgAu) 2 Te 
 
 COL. White. With galena, very pale grayish brownish white (nearly 
 the same as hessite ?). 
 
 HARD. Low. SURF. Smooth. H. 2.5-3 < galena. 
 
 CHEM. 1. HNOs. Instantly effervesces, then dark brown. Rubs clean, 
 
 showing roughly etched surface. 2. KCN . 3. HC1 . 4. 
 
 Aq. Reg. Instantly brilliant iridescent, with effervescence. Fumes 
 tarnish brilliant. Rubs clean easily. 5. FeCls. Quickly iridescent, 
 deepening rapidly. Rubs clean easily. 6. KOH . 
 
 DIFF. Chem. 5. 
 
 i 
 
 i 1 
 
 r* Z 
 
 <U ><*s 
 
 g 
 
 s I 
 
 137 q, 
 
 m 
 
B 
 
 >J5 WHITE 
 
 JS HARDNESS Low 
 
 ^ GALENA WHITE 
 
 ** SAME AS GALENA OB DARKER 
 
 HN0 3 
 S 
 
 GQ 
 
 1 
 I 
 
 KERMESITE Sb 2 S 2 O 
 
 COL. White. With galena, slightly darker, almost same; with silver, 
 
 pale bluish white, very nearly same. Red transparent by oblique 
 
 light. 
 
 HARD. Low. SURF. Smooth. H. 1-1.5. 
 
 CHEM. 1. HNO 3 . Quickly light brown, persistent. 2. KCN. Slowly 
 
 darkens, slightly, and rubs to lighter brown. 3. HC1 - . 4. Aq. 
 
 Reg. Effervesces vigorously, and darkens slightly. 5. FeCla - . 6. 
 
 KOH. Instantly iridescent, then coated with bright yellow, which 
 
 rubs off easily. 
 DIFF. Col. Chem. 4, 6. 
 
 STIBNITE Sb 2 S 3 
 
 COL. White. With galena, very faintly creamy, with silver, faint 
 
 grayish white. Differently oriented sections vary slightly in color. 
 HARD. Low. SURF. Smooth. H. 2. 
 
 CHEM. 1. HNOs. Quickly darkens, at last dark brown. 2. KCN. Dis- 
 
 solves and roughens surface, but does not change color. 3. HC1 - . 
 
 4. Aq. Reg. Blackens rapidly with effervescence. 5. FeCls - . 6. 
 
 KOH. Quickly coated with bright orange yellow, soon turning reddish 
 
 brown. Washes off easily, leaving rough surface. 7. NaOH - . 
 
 8. NH 4 OH - . 
 DIFF. Col. Chem. 4, 6. 
 
 HESSITE Ag 2 Te 
 
 COL. White. With galena, very slightly creamy, almost the same; 
 with silver, distinctly bluish gray. 
 
 HARD. Low. SURF. Smooth. H. = 2-3 < gold. 
 
 CHEM. 1. HNOa. Instantly iridescent, then darkens to dark brown. 
 Rubs clean, leaving a roughened surface. 2. KCN. Slowly blackens 
 and dissolves, giving a very rough surface. 3. HC1 - ? 4. Aq. Reg. 
 Instantly brilliant iridescent with effervescence. Fumes tarnish 
 brilliant. Rubs clean easily. 6. FeCla. Instantly iridescent. Rubs 
 clean easily. 6. KOH - . 
 
 DIFF. Chem. 5 (1), 6. 
 
 I 
 
 GUEJARITE See page 103. 
 
 03 
 
 BROGNIARDITE See page 110. 
 
 2 
 
 i 
 
GRAY 
 
 3 
 
 
 
 1 
 g 
 
 139 ^ 
 
 e 
 
 (0 
 
8 
 
 5 WHITE 
 
 C; HARDNESS Low 
 
 ^ GALENA WHITE 
 
 ^ SAME AS GALENA OK DARKER 
 
 HNO 3 NEQ. 
 
 ^ KOH NEQ. 
 
 No Eff. Aq. Reg. 
 
 I 
 
 JALPAITE 3 AgjS-CusS ? 
 
 COL. White. With galena, very pale creamy gray, almost same; 
 
 with silver, dull grayish white; with argentite, pale brownish cream ; 
 
 with tetrahedrite, very close, almost same (?). 
 
 HARD. Low. SURF. Smooth. H. 2-2.5. 
 
 CHEM. 1. HNO 3 - . 2. HNO 3 cone, - . 3. KCN. Very slowly 
 
 browned, develops scratches; rubs off rather easily. 4. HC1. Slowly 
 
 effervesces a little, solution turns green, surface is roughened. 5. 
 
 Aq. Reg. Instantly iridescent, deepens rapidly, persistent. 6. 
 
 FeCl 8 . 7. KOH - . 
 DIFF. Chem. 3, 5. 
 
 MALTILDITE AgBiS 2 
 
 COL. White. With galena, very slightly creamy or grayish white, 
 almost same; with silver, distinctly grayish white; with matildite 
 (?) from Japan, grayer, less creamy. 
 
 HARD. Low. SURF. Smooth. H. 2.5? 
 
 CHEM. 1. HNO 3 - . 2. KCN - . 3. HC1 - . 4. HC1 cone. - . 
 5. Aq. Reg. Fumes instantly tarnish brilliant iridescent, acid same, 
 less quickly, and darker finally. Effervesces slightly (?). Rubs 
 easily to a clean, very slightly roughened surface. 6. FeCli - . 7. 
 KOH - . 
 
 DIFF. Chem. 2, 5. 
 
 ^ UNKNOWN (Tonopah) See page 114. 
 
 I 
 I 
 
 140 
 
GRAY 
 
 Eflf. Aq. Reg. 
 
 SCHIRMERITE ( 
 
 COL. White. With galena, practically the same (faintly creamier). 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNO 3 - . 2. KCN - . 3. HC1 - . 4. Aq. Reg. In- 
 stantly iridescent, then blackens, with effervescence; coated with 
 white. Rubs to roughened iridescent surface. 5. FeCls - . 6. 
 KOH - . 
 
 DIFF. Col. Chem. 4, 6. 
 
 RATHITE Pb(As,Sb),S ? 
 
 COL. White. With galena, very pale bluish (grayish) white. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs - . 2. KCN - . 3. HC1 - . 4. Aq. Reg. Effer- 
 
 vesces quickly and turns brown, then black; thinly coated with 
 
 white. Rubs to rough gray surface. 5. FeCls - . 6. KOH. 
 
 Rather quickly pale brown, then pale purple and blue iridescent. 
 
 Rubs to very pale purplish color. 
 DIFF. Chem. 6. 
 
 NOTE. Same chemical properties as seligmannite, but looks 
 
 bluish instead of creamy. 
 
 LENGENBACHITE Pb 6 (AgCu) 2 As4S 
 
 COL. White. With galena, very pale grayish white; with tetra- 
 
 hedrite, distinctly whiter. 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNOs - ? (Edge of specimen slowly tarnished iridescent, 
 
 but perhaps due to sealing wax mount.) 2. KCN - . 3. HC1 - . 
 
 4. Aq. Reg. Instantly iridescent, effervesces, finally blackens. Rubs 
 
 to faintly gray, roughened surface. 5. FeCls - . 6. KOH - . 
 DIFF. Chem. 4, 6. 
 
 CINNABAR HgS 
 
 COL. White. With galena, pale bluish gray; with tetrahedrite, dull 
 grayish white. Transparent brilliant red with oblique light. 
 
 HARD. Low. SURF. Smooth. H. 2-2.5. 
 
 CHEM. 1. HNOs . 2. KCN . 3. HC1 cone, . 4. Aq. Reg. 
 
 Effervesces and darkens, iridescent. Rubs clean. 5. FeCla . 6. 
 
 KOH . 7. (NH4) 2 Sx . 
 
 DIFF. Col. 
 
 T3 O 
 
 * U J 
 
 
 MATILDITE See page 140. 
 
 OJ 
 
 POLYBASITE See page 105. J* 
 
 g 
 
 BOURNONITE See page 92. ^ J* 
 
 141 C 
 
 e 
 
 (0 
 
6 
 
 Hj WHITE 
 
 HARDNESS Low 
 
 ^ GALENA WHITE 
 
 SAME AS GALENA OR DARKER 
 
 ^ HNOs NEG. 
 
 < KOH 
 
 a 
 
 UJ 
 
 bo LIVINGSTONITE HgSb 4 S7 
 
 ,* COL. White. With galena, very pale grayish white, practically the 
 
 ^ same; with silver, very pale (bluish) grayish white. Transparent 
 
 w deep red by oblique light. 
 
 Q HARD. Low. SURF. Smooth. H. 2. 
 
 J^, CHEM. 1. HNO 3 - . 2. HNOs cone, - . 3. KCN. Very slowly faint 
 
 Jrj gray. 4. HC1 - . 5. HC1 cone. - . 6. Aq. Reg. Slowly brown 
 
 H with effervescence. 7. FeClj - . 8. KOH. Instantly bright yellow- 
 
 ish brown. 
 DIFF. Col. Chem. 5, G, 8. 
 
 STEPHANITE Ag 6 SbS 4 
 
 COL. White. With galena, very pale grayish white; with silver, de- 
 cidedly bluish gray; with argentine, almost pure white; with tetra- 
 hedrite, bluish gray; with proustite, nearly pure white. 
 
 HARD. Low. SURF. Smooth. H. 2-2.5. 
 
 CHEM. 1. HNOs - . 2. KCN. Immediately darkens; rubs clean 
 easily, leaving brown edged cracks. 3. HC1 - . Fumes very 
 slowly brown, then iridescent. Rubs off. 4. HC1 cone, - . Fumes 
 tarnish iridescent, persistent, forming a brilliant ring on the surface. 
 5. Aq. Reg. Instantly iridescent, blackens with slight effervescence; 
 rubs to dark gray, persistent, and shows a shallow solution pit. 
 Fumes tarnish brighter than acid. 6. FeCl 3 . Slowly develops little 
 black flecks, white by oblique light. Rubs clean easily. 7. KOH. 
 Rapidly darkens to dark brown; rubs clean easily, showing solution 
 surface. 8. NaOH. Same as KOH, but not as rapid. 9. NH 4 OH - . 
 10. (NH 4 ) 2 S V . Slowly brown, rubs clean easily. 
 
 DIFF. Chem. 4, 7. 
 
 SARTORITE PbAs 2 S 4 
 
 COL. White. With galena, very close. 
 
 HARD. Low. SURF. Smooth. H. = 3? 
 
 CHEM. 1. HNOs - . 2. KCN - . 3. HC1 - . 4. Aq. Reg. - , or 
 
 very slowly faint brownish (doubtful, because of mounting wax) . 5. 
 
 FeCla - . 6. KOH. Quickly faint gray (?), slowly etches, de- 
 
 veloping structure. Rinses off white showing etching lines (cleavage 
 
 or structure). 
 DIFF. Chem. 4, 6. 
 
 DUFRENOYSITE Pb 2 As 2 S 6 
 
 COL. White. With galena, very close (slightly creamy ?). 
 HARD. Low. SURF. Smooth. H. - 3? 
 
 CHEM. 1. HNO 3 - . 2. KCN - . Or very pale tarnish, slowly? 4. 
 Aq. Reg. Quickly brown, then iridescent, effervesces slowly. Finally 
 very dark, with white coating. Rubs to blackened rough surface. 
 * 5. FeCl 3 - . 6. KOH. Rather quickly pale iridescent, developing 
 
 C different grains; then gray. Rubs clean easily, showing very 
 
 > strongly differential etching. 
 
 J DIFF. Chem. 4, 6. 
 
 NOTE. Called binnite by Heusser. 
 
 BERTHIERITE See page 103. 
 MIARGYRITE See page 115. 
 
 142 
 
 i 
 
GRAY 
 
 
 I 
 
 <o 
 -0 
 
 
 
 (0 
 
 s 
 
 CO 
 
 143 
 
GRAY 
 
 HARDNESS HIGH 
 HC1 CONG. 
 
 FRANKLINITE FeZnMnO-(FeMn) s O 
 
 COL. Gray. With galena, dull gray; with sphalerite, distinctly 
 
 lighter; with hematite, grayer. 
 HARD. High. SURF. Shiny, pitted. H. 5.5-6.5. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 cone, . Acid turns 
 
 yellowish brown, slowly. 4. Aq. Reg. Same as HC1 cone. 5. 
 
 KOH . 6. FeCla . 
 
 DIFP. Col. Chem. 3. 
 
 NOTE. Very hard to polish free from pits. 
 
 PSILOMELANE H 4 MnOs ? 
 
 COL. Gray. With sphalerite, somewhat lighter, and creamy; with 
 
 galena, dull gray. 
 
 HARD. High. SURF. Smooth. H. 5-6. 
 
 CHEM. 1. HNO 3 cone, . 2. HC1. Quickly darkens, rubs to pale 
 
 brown. 3. HC1 cone. Immediately blackens and dissolves. Acid 
 
 turns brown. 4. Aq. Reg. Very slowly faint brown, persistent. 5. 
 
 KOH . 6. FeCls . , 
 
 DIFF. Col. Chem. 2, 3. 
 
 MAGNETITE See page 91. 
 
 i 
 
 144 
 
GRAY 
 
 (A 
 
 2 
 
 a 
 c* 
 
 E 
 
 s 
 
 Cft 
 M 
 
 tu 
 a 
 
 Q( 
 
 145 E 
 
GRAY 
 
 HARDNESS HIGH 
 HC1 CONG. NEO. 
 
 Aq. Reg. Neg. 
 
 0? CASSITERITE SnOa 
 
 ^ COL. Gray. With galena, dull brownish (?) gray; with sphalerite, 
 
 slightly lighter (?) and creamy; with hematite, dull gray; with 
 
 ^J magnetite, dull gray; sometimes transparent yellow or brown by 
 
 jjj oblique light. 
 
 5 HARD. High. SURF. Shiny, pitted. H. 6-7. 
 
 r\ CHEM. 1. HNO 3 . 2. HNO 3 cone. . 3. KCN . 4. HC1 
 
 cone. . 5. Aq. Reg. . 6. FeCU . 7. KOH . 
 
 %, DIFP. Col. Chem. inertness. 
 
 >J NOTE. Very hard to polish free from pits. 
 
 LIMONITE 2 Fe 2 O 3 -3 H 2 O ? 
 
 COL. Gray. With galena, pale slate gray to dull gray; with sphaler- 
 ite, slightly bluish gray. Often transparent reddish brown or yellow 
 by oblique light. Color appears brighter on a smooth surface than 
 on a rough one. 
 
 HARD. High. SURF. Smooth, or pitted. H. 5-5.5. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 cone, . 4. Aq. Reg. 
 
 . 5. FeCk . 6. KOH . 
 
 DIFF. Col. Chem. 
 
 CHROMITE FeCr,O 
 
 COL. Gray. With galena, very dull gray; with sphalerite, darker, 
 
 dull gray. 
 
 HARD. High. SURF. Shiny, much pitted. H. 5.5. 
 
 CHEM. 1. HNOs . 2. KCN . 3. HC1 cone. . 4. Aq. Reg. 
 
 DIFF.' Col Surf. 
 
 NOTE. Very hard to polish free from pits. 
 
 RUTILE See page 90. 
 FRANKLINITE See page 144. 
 U HEMATITE See page 90. 
 
 
 
 ^ ILMENITE See page 90. 
 
 G 
 
 
 146 
 
E 
 
 O 
 
 E 
 
 Aq. Reg. 
 
 URANINITE (A uranate of uranyl with other bases) Q 
 
 COL. Gray. With sphalerite, slightly darker and faintly brown- ON 
 
 ish (?). ^ 
 
 HARD. High. SURF. Smooth. H. 5.5 > si. w 
 
 CHEM. 1. HNOs . 2. KCN . 3. HC1 . 4. HC1 cone, . * 
 
 5. Aq. Reg. Slowly blackens, rubs off to darker gray, roughened 
 
 surface. 6. FeCls. Slowly darkens, roughens slightly, persistent. 
 
 7. KOH . 
 
 DIFF. Col. Chem. 5, 6 
 
 s 
 
 UJ 
 
 UJ 
 
 Q 
 Q^ 
 
 E 
 
 
 
 s 
 
 I 
 
 o 
 < 
 
GRAY 
 
 HARDNESS MEDIUM 
 
 HC1 Neg. 
 
 SPHALERITE ZnS 
 
 COL. Gray. With galena, bright steely gray. Sometimes bluish, or 
 
 slate gray, or reddish when in very small areas. Transparent yellow 
 
 to brown by oblique light. Color only slightly different for black and 
 
 for pure varieties. 
 
 HARD. Medium. SURF. Smooth. H. 3.5-4 =or > cp. 
 
 CHEM. 1. HNO 3 . Faintly browned, slowly, often showing crystal 
 
 structure. 2. HNO 3 cone. Same. 3. KCN . 4. HC1 . 5. 
 
 HC1 cone. . 6. Aq. Reg. Instantly effervesces and blackens. 
 
 Rubs off to show rough etched surface. Fumes tarnish brown. 7. 
 
 FeCls . 8. KOH . 9. (NH^Sx . 10. K 4 Fe(CN) 6 . 
 
 11. K3Fe(CN)6 . 12. Iodine . 13. NH 4 OH . 
 
 DIFF. Col. Chem. 1. 
 
 WURTZITE ZnS 
 
 COL. Gray. Transparent yellow or brown by oblique light. Same 
 
 color as sphalerite. 
 
 HARD. Medium. SURF. Smooth. H. 3.5-4. 
 
 CHEM. 1. HNOs. Slowly faint brown. 2. HNO 3 cone. Same. 3. 
 
 KCN . 4. HC1 . 5. HC1 cone. . 6. Aq. Reg. . 7. 
 
 FeCl 3 . 8. KOH r. 
 
 DIFF. Chem. 1. 
 
 VOLTZITE Zn5S 4 O 
 
 COL. Gray. With sphalerite, slightly lighter gray. Transparent 
 
 reddish yellow or brown by oblique light. 
 
 HARD. Medium. SURF. Smooth. H. 4-4.5. 
 
 CHEM. 1. HNO 3 . Fumes tarnish faintly. 2. KCN . 3. HC1 . 
 
 4. Aq. Reg. . Fumes tarnish brown. 5. FeCls . 6. KOH . 
 
 DIFF. Chem. 1. 
 
 ER YTHROZINCITE (MnZn) S 
 
 COL. Gray. About like limonite. 
 Occ. Coatings and yeinlets on and in pyrite. 
 HARD. Low to medium. SURF. Smooth. H. 
 
 CHEM. 1. HNO 3 ? 2. KCN . 3. HC1 . 4. Aq. Reg. . 
 
 5. FeCls . 6. KOH . 
 
 DIFF. Chem. 1, 4. 
 
 URANINITE See page 147. 
 ARGYRODITE See page 105. 
 
 148 
 
HC1 
 
 CUPRODESCLOIZITE 
 
 \ ' MV/* 2vy-*AZW 
 
 GOL. Gray. With galena, dull gray. Sometimes transparent green- 
 ish or brownish with oblique light. 
 
 HARD. Medium. SURF. Smooth. -V H35 
 
 CHEM. 1 HNO 3 . Quickly blackens and dissolves; shows yellow coat 
 ing with oblique light. 2. KCN . 3. HC1 same as HNO 3 4. 
 Aq. Reg. Dissolved, coated quickly with yellowish green, which 
 shows white after acid is washed off. Fumes tarnish iridescent in- 
 stantly, then tarnish turns black. 5. FeCla . 6. KOH -. 
 
 DIFF. Chem. 1. 
 
 CUPRITE See page 117. 
 ALABANDITE See page 96. 
 
 Q 
 
 TENORITE See page 92. S 
 
 DELAFOSSITE See page 92. CO 
 
 Q 
 
 s 
 
 U 
 
 a 
 
 
GRAY 
 HARDNESS Low 
 
 LORANDITE TlAsS 2 
 
 GOL. Gray. With galena, distinctly gray; with sphalerite, slightly 
 darker. Transparent orange red by oblique light. 
 
 HARD. Low. SURF. Smooth. 
 
 CHEM. 1. HNO 3 . 2. KCN . 3. HC1 . 4. Aq. Reg. . 5. 
 
 FeCla . 6. KOH. Instantly coated with orange. Rubs off to 
 
 show very rough solution surface. 
 
 DIFF. Chem. 6. 
 
 STANNITE See page 108. 
 "PETZITE" See page 106. 
 ARGYRODITE See page 105. 
 ERYTHROZINCITE See page 148. 
 TAPALPAITE " (GRAY) See page 107. 
 
 160 
 
I 
 
 Q 
 
 151 
 
MISCELLANEOUS TABLES 
 
 INDEX 
 
CONDENSED DETERMINATIVE TABLE 
 
 The more important minerals are printed in conspicuous type, 
 so that they can be readily picked out. The parentheses around a 
 mineral name indicate that the reaction changes in character as it 
 progresses, and that the first stage places the mineral in a certain 
 group, while the final effect puts it elsewhere. For example, mar- 
 casite first turns brown, and then finally blackens, with HNO 3 , and 
 so is referred to in parentheses under HNO 3 Eff. Browns, and 
 without parentheses under HNO 3 Eff. Blackens FeCl 3 neg. 
 
 HNO 3 Neg. 
 
 KCN neg. 
 
 KCN 
 
 Aq. Reg. neg. 
 
 KOH neg. 
 
 Cassiterite Lorandite 
 
 Argentite 
 
 Chromite Magnetite 
 
 Argyrodite 
 
 Erythrozincite Millerite 
 
 Covellite 
 
 Franklinite Molybdenite 
 
 Gold 
 
 Hematite Rutile 
 
 Jalpaite 
 
 Ilmenite Sartorite 
 
 Onofrite 
 
 Lehrbachite 
 
 Polybasite 
 
 Limonite 
 
 
 Aq. Reg. 
 
 
 KOH 
 
 No Eff. 
 
 Eff. 
 
 
 Berthierite 
 
 Bournonite 
 
 Livingstonite 
 
 Chalcostibite 
 
 Dufrenoysite 
 
 Miargyrite 
 
 Chalcopyrite 
 
 Kalgoorlite 
 
 Orpiment 
 
 Delafossite 
 
 Lengenbachite 
 
 Proustite 
 
 Matildite (?) 
 Psilomelane 
 
 (Onofrite) 
 Rathite 
 
 Pyrargyrite 
 Stephanite 
 
 Regnolite 
 
 Schirmerite 
 
 
 Sperrylite 
 
 Seligmannite 
 
 
 Tenorite 
 
 Stiitzite 
 
 
 Tiemannite 
 
 Vrbaite 
 
 
 Uraninite 
 
 
 
 Fumes HNO ; 
 
 Chalmersite 
 Enargite 
 Hauerite 
 Luzonite 
 Pearceite 
 Polyargyrite 
 
 Sulvanite 
 Tennantite 
 Tetrahedrite 
 Voltzite 
 
 HNO. 
 
 No Eff. 
 Blackens 
 FeCls neg. 
 
 Bismuthinite 
 Cuprodescloizite 
 Epiboulangerite 
 Freieslebenite 
 Galenobismutite 
 Geocronite 
 Gersdorffite 
 
 Glaucodot 
 Guejarite 
 Jamesonite 
 Jordanite 
 Meneghinite 
 Realgar 
 Semseyite 
 
 Eff. 
 Blackens 
 FeCl 3 neg. 
 
 Aikinite 
 Alabandite 
 Algodonite (gray) 
 Arsenopyrite 
 Boulangerite 
 Cinnabar 
 Cosalite 
 
 Marcasite 
 Dognacskaite 
 Horsfordite 
 Mohawkite (cream) 
 Niccolite 
 Zinkenite 
 
 154 
 
OF THE OPAQUE MINERALS 
 
 155 
 
 No Eff. (continued') 
 
 Eff. (continued) 
 
 FeCls 
 
 Breithauptite 
 Clausthalite 
 Euoairite 
 Galena 
 SUver 
 Tetradymite 
 
 fr T 
 
 ; -P 
 
 FeCl 3 
 
 Algodonite (cream) 
 Arsenic 
 Bismuth 
 Chilenite 
 Cuprite 
 Hessite (?) 
 Huntilite 
 Maucherite 
 Melonite 
 Mohawkite (gray) 
 
 Naumannite 
 Petzite (?) 
 Rickardite 
 Safflorite 
 Skutterudite 
 Smaltite 
 Steinmannite 
 Tapalpaite 
 Tellurium 
 
 Browns 
 Slowly 
 
 Aguilarite 
 Baurnhauerite 
 Brogniardite 
 Cobaltite 
 Coloradoite 
 Crookesite 
 Cylindrite 
 Famatinite 
 Hauchecornite 
 Kermesite 
 Linnaeite 
 Lollingite 
 
 Matildite (?) 
 Metacinnabarite 
 Pentlandite 
 Polydymite 
 (Polytelite) 
 Pyrrhotite 
 Sphalerite 
 Stylotypite 
 Wittichenite 
 Wurtzite 
 
 Browns 
 
 Altaite 
 (Arsenic) 
 Bornite 
 Calaverite 
 Petzite 
 Pyrite 
 Whitneyite 
 Willyamite 
 (Marcasite) 
 
 > 
 
 Quickly 
 
 Chloanthite 
 Emplectite 
 Frankeite 
 (Galenobismutite) 
 Hessite 
 (Jamesonite) 
 Rammelsbergite 
 
 (Stannite) 
 Stibnite 
 Sylvanite 
 
 (Teallite) 
 (Tetradymite) 
 (Ullmannite) 
 " Bronze Enargite " 
 
 Turns iridescent 
 FeCls neg. 
 
 Andorite 
 Beegerite 
 (Cylindrite) 
 (Frankeite) 
 Freibergite 
 (Gersdorffite) 
 Guanajuatite 
 (Guejarite) 
 Guitermanite 
 
 Lengenbachite 
 Nagyagite 
 Polytelite 
 Semseyite 
 Stannite 
 Stern bergite 
 Ullmannite 
 
 Turns iridescent 
 
 (Arsenopyrite) 
 Chiviatite 
 (Dognacskaite) 
 Kallilite 
 (Steinmannite) 
 (Willyamite) 
 
 FeCls 
 
 Berzelianite 
 (Breithauptite) 
 (Coloradoite) 
 Dyscrasite 
 
 (Hessite) 
 Lillianite 
 Rezbanyite 
 Teallite 
 
 Turns blue 
 
 Umangite 
 
 Turns blue 
 Chalcocite 
 
 Color unchanged 
 
 Copper 
 Stromeyerite 
 
 Color unchanged 
 Realgar 
 
ODOR AND STREAK OF MINERALS 
 
 A number of minerals carrying arsenic give off a characteristic 
 odor when ground dry on the coarse carborundum wheel. Many 
 arsenic minerals do not give this, however, so absence of odor does 
 not necessarily mean absence of arsenic. Selenium occasionally 
 gives an odor under the same conditions. Some minerals leave a 
 characteristic streak when polished on the canvas wheel. These 
 several groups of minerals are listed below. 
 
 ARSENIC ODOR 
 
 Arsenic Lollingite 
 
 Arsenopyrite Safflorite 
 
 Chloanthite Smaltite 
 
 Glaucodot Skutterudite 
 
 (Enargite under some conditions, but not usually) 
 
 SELENIUM ODOR 
 Eucairite 
 
 (Probably some other selenides also, but none were obtained large enough to test fairly 
 in this respect.) 
 
 STREAK 
 
 Tetrahedrite reddish 
 Tennantite reddish 
 Hauerite orange 
 Sphalerite brown to whitish 
 Limonite brown to reddish 
 
 156 
 
MINERALS TABULATED BY ELEMENTS 
 
 (Brackets indicate that the enclosed mineral has not been studied in this investigation) 
 
 ARSENIC 
 
 Algodonite CueAs (mixture) 
 
 Argyropyrite Ag, Fe, S, As 
 
 Arsenic As 
 
 Acsenopyrite FeAsS 
 
 [Badenite (CoFeNi) 2 (AsBi) 8 ] 
 
 Baumhauerite Pb4AseSi 3 
 
 "Bronze Enargite" (CuSn), (AsSb), 83 ? 
 
 Chloanthite NiAsz 
 
 Cobaltite CoAsS 
 
 Domeykite CusAs (+Sb) (mixture) 
 
 Dufrenoysite Pb 2 As 2 S6 
 
 Enargite Cu 3 AsS4 
 
 [Epigenite R 7 As 2 Si 2 (R = 8 Cu + 3 Fe)] 
 
 Gersdorffite NiAsS 
 
 Glaucodot (CoFe)AsS 
 
 Guitermanite PbsAsaSe 
 
 Huntilite AgsAs ? 
 
 [Hutchinsonite Tl, Ag, Cu, Pb, As, S ?] 
 
 Jordanite Pb4As 2 Sr 
 
 Kallilite NiBiS + As, Sb ? 
 
 Lengenbachite Pbs(AgCu) ^34818 
 
 [Liveingite PbsAssSi?] 
 
 Lollingite FeAs 2 
 
 Lorandite TlAsS 2 
 
 Luzonite CusAsS4 
 Maucherite NisAss 
 Mohawkite CusAs (mixture) 
 Niccolite NiAs 
 Orpiment As 2 Sa 
 Pearceite Ag 9 AsS 
 Proustite Ag 3 AsS 3 
 Rammelsbergite NiAss 
 Rathite Pb, As, Sb, S ? 
 Realgar AsS 
 Regnolite Cu 7 As 2 Si 2 
 Safflorite CoAs 2 
 Sartorite PbAs2S4 
 Seligmannite CuPbAsSs 
 Skutterudite CoAss 
 Smaltite CoAs 2 
 [Smithite AgAsS 2 ] 
 Sperrylite PtAs 2 
 Steinmannite Pb(As, Sb, S) 
 Tennantite CugAs 2 S 7 
 [Trechmannite AgAsS 2 ] 
 Vrbaite TlAs 2 SbS 5 
 Whitneyite CuoAs 
 [Xanthoconite 
 
 ANTIMONY 
 
 Andorite 
 
 Berthierite FeSb 2 S 4 
 
 Boulangerite PbsSb^o 
 
 Bournonite (PbCu 2 ) 3 Sb 2 S 6 
 
 Breithauptite NiSb 
 
 Brogniardite PbAg 2 Sb 2 S 5 ? 
 
 " Bronze Enargite " (CuSn), (AsSb), S ? 
 
 Chalcostibite CuSbS 2 
 
 Cylindrite 3 PbSnS 2 + SnFeSb 2 S 8 
 
 [Diaphorite (PbAg 2 ) 5 Sb4Sn] 
 
 Domeykite CuaAs + (Sb) (mixture) 
 
 Dyscrasite AgeSb 
 
 [Eichbergite (CuFeJBiaSbsSs] 
 
 Epiboulangerite PbsSb 2 S8 
 
 Famatinite Cu 3 SbS 4 
 
 Frankeite 3 PbSnS 2 + PbsFeSbtSg 
 
 Freibergite (CuAg) 8 Sb 2 S7 
 
 Freieslebenite (PbAg 2 ) 5 Sb4Su 
 
 Geocronite Pb 5 Sb 2 S 8 
 
 Guejarite Cu 2 Sb 4 S7 
 
 Hauchecornite (NiCo) 7 (BiSbS) 8 
 
 [Histrixite Cu 5 Fe5Bi 14 Sb4S 3 7 (mixture) ?] 
 
 Horsfordite CueSb ? 
 
 Jamesonite Pb 2 Sb 2 S6 
 
 Kallilite NiBiS + As, Sb ? 
 
 Kermesite Sb 2 S 2 O 
 
 Kobellite Pb 2 (BiSb) 2 S 5 (mixture ?) 
 
 Livingstonite HgSb4S? 
 
 Meneghinite Pb4Sb2S 7 
 
 Miargyrite AgSbS 2 
 
 Nagyagite Au 2 Pb l0 Sb 2 Te6Si 8 
 
 Plagionite PbsSbsSn 
 
 Polyargyrite Ag 2 4Sb 2 Sis 
 
 Polybasite Ag 9 SbS 6 
 
 Polytelite (PbAgFeZn) 4 Sb 2 S7 ? 
 
 Pyrargyrite AgsSbSs 
 
 [Pyrostilpnite Ag 3 SbS 3 ] 
 
 Rathite Pb, As, Sb, S ? 
 
 [Richmondite ReSb 2 S9 (R = Pb, Cu, Ag, Fe, 
 
 Zn)] 
 
 [Sampsonite" (Ag 4 Mn)Sb 2 S] 
 Semseyite PbrSbeSw 
 Stephanite Ag B SbS 4 
 (Steinmannite) Pb(As, Sb, S) 
 Stibnite Sb 2 S 3 
 
 Stylotypite (Cu 2 Ag 2 Fe) s Sbi& 
 Tetrahedrite CusSbsS? 
 Ullmannite NiSbS 
 Vrbaite TlAs 2 SbS B 
 Willyamite (CoNi)SbS 
 Zinkenite PbSb 2 S 4 
 
 157 
 
158 
 
 MICROSCOPICAL DETERMINATION 
 
 BISMUTH 
 
 Aikinite PbCuBiSj 
 [Badenite (CoFeNi),(AsBi),] 
 Beegerite PbeBi 2 S 
 Bismuth Bi 
 Bismuthinite BijSs 
 Chilenite AgBi ? 
 Chiviatite Pb 2 BiSn 
 Cosalite PbzBizSs 
 [Cuprobismutite CueBigSu] 
 Dognacskaite Bi, Cu, S ? 
 [Eichbergite (CuFe)Bi3Sb 8 S 6 ] 
 Emplectite CuBiS* 
 Galenobismutite PbBi 2 S4 
 [Grunlingite Bi 4 TeS s ] 
 Guanajuatite Bi 2 Se 3 
 Hauchecornite (NiCo) 7 (Bi, S, Sb) 8 
 
 [Histrixite 
 
 KaUiUte Ni, Bi, S ? (+Sb, As) 
 
 Klaprotholite GueBi4S 
 
 Kobellite Pb2(BiSb) 2 S 8 (mixture?) 
 
 Lillianite PbsBi^ 
 
 Matildite AgBiSs 
 
 [Platynite PbBi 2 Sa] 
 
 Plenargjrrite AgBiS 2 ? 
 
 Rezbanyite Pb4BiioS 19 
 
 Schapbachite PbAg 2 Bi 2 S 6 ? (mixture) 
 
 Schirmerite (Ag 2 Pb)3Bi 4 S 9 
 
 Tapalpaite 3 Ag z (S, Te)-Bi 2 CSTe) 
 
 Tetradymite Bi 2 (TeS) 3 
 
 [Von Diestite Ag, Bi, Te ?] 
 
 [Weibullite Pb 2 Bi 4 S 5 Se3] 
 
 Wittichemte CuaBiSs 
 
 [Greenockite CdSJ 
 
 [Oldhamite CaS] 
 
 CADMIUM 
 
 CALCIUM 
 
 Chromite FeCr 2 O4 
 
 CHROMIUM 
 
 [Daubreelite FeCrtSi] 
 
 [Badenite (CoFeNi) 2 (AsBi) 3 ] 
 Cobaltite CoAsS 
 Glaucodot (CoFe)AsS 
 Hauchecornite (NiCo) 7 (Bi, S, Sb) a 
 Linnaeite 
 
 COBALT 
 
 Safflorite CoAst 
 Skutterudite CoAsa 
 Smaltite CoAs, 
 [Sychnodymite (CoCu)4S] ? 
 WiUyamite (CoNi)SbS 
 
OF THE OPAQUE MINERALS 
 
 159 
 
 COPPER 
 
 Aikinite PbCuBiSj 
 
 Algodonite Cu&As (mixture) 
 
 Berzelianite Cu 2 Se 
 
 Bornite Cu 6 FeS 4 
 
 Bournonite (PbCuOsSb^e 
 
 1 ' Bronze Enargite ' ' (CuSn) , (SbAs) , S ? 
 
 Chalcocite Cu 2 S 
 
 Chalcopyrite CuFeS 2 
 
 Chalcostibite CuSbSj 
 
 Chalmersite CuFe 2 S 3 
 
 Copper Cu 
 
 Covellite CuS 
 
 Crookesite (CuTlAg^e 
 
 Cuprite Cu 2 O 
 
 [Cuprobismutite CueBiaSu] 
 
 Cuprodescloizite (PbZnCu) 4 V 2 O-H 2 O 
 
 Delafossite Cu, Fe, O 
 
 Dognacskaite Bi, Cu, S ? 
 
 Domeykite CuaAs ( +Sb) (mixture) 
 
 [Eichbergite (CuFe)Bi3Sb 2 S 6 ] 
 
 Emplectite CuBiS 2 
 
 Enargite CusAsS 4 
 
 [Epigenite R 7 As 2 Si 2 (R = 8 Cu + 3 Fe) ] 
 
 Eucairite Cu 2 Se-Ag 2 Se 
 
 Famatinite CusSbS4 
 
 Freibergite (CuAg) 8 Sb 2 S7 
 
 Guejarite 
 
 [Histrixite CmFesBii^b^? (mixture)] 
 
 Horsfordite Cu 6 Sb 
 
 [Hatchinsonite Tl, Ag, Cu, Pb, As, S ?] 
 
 Jalpaite CuuS-3 Ag 2 S 
 
 Klaprotholite CueBi^* 
 
 Lengenbachite Pb 6 (AgCu) 2 As4Su 
 
 Luzonite Cu 3 AsS 4 
 
 Mohawkite CusAs (mixture) 
 
 Regnolite Cu7As 2 Si 2 
 
 [Richmondite RoSb 2 S9 (R = Pb, Cu, Ag, Fe, 
 
 Zn)J 
 
 Rickardite Cu 4 Te 3 
 Seligmannite CuPbAsSs 
 Stannite Sn, Cu, Fe, Zn, S ? 
 Stromeyerite (AgCu) 2 S 
 Stylotypite (Cu 2 Ag 2 Fe) 3 Sb 8 S 
 Sulvanite Cu 3 VS 4 
 [Sychnodymite (CoCu)4S 6 ?] 
 Tennantite 
 Tenorite CuO 
 Tetrahedrite 
 Umangite Cu 3 Se 2 
 Whitneyite CuaAs 
 Wittichenite Cu 3 BiS 
 
 Argyrodite Ag 8 GeS 6 
 
 Calaverite AgAuTej 
 Gold Au 
 
 Kalgoorlite HgAu 2 Ag 8 Tee 
 
 Nagyagite Au 2 Pb 10 Sb 2 Te 6 Si 5 
 
 [Argentopyrite Ag, Fe, S ?] 
 
 Argyropyrite Ag, Fe, S, As ? 
 
 Arsenopyrite FeAsS 
 
 [Badenite (CoFeNi) 2 (AsBi) 3 ] 
 
 Berthierite FeSb 2 S 4 
 
 Bornite Cu 8 FeS 4 
 
 Chalcopyrite CuFeS 2 
 
 Chalmersite CuFe 2 S 3 
 
 Chromite FeCr 2 O 4 
 
 Cylindrite 3 PbSnS 2 + SnFeSbuSs 
 
 [Daubreelite FeCr 2 S 4 ] 
 
 Delafossite Cu, Fe, O 
 
 [Eichbergite (CuFe)Bi3Sb 3 S 8 ] 
 
 [Epigenite R 7 As 2 Si 2 (R = 8 Cu + 3 Fe)l 
 
 Frankeite 3 PbSnS 2 + Pb 2 FeSbjS 8 
 
 Franklinite FeaZnMnsCh 
 
 Frieseite AgFe 2 Ss 
 
 Glaucodot (CoFe)AsS 
 
 GERMANIUM 
 
 [Canfieldite Ag8(SnGe)S 8 J 
 
 GOLD 
 
 Petzite (AgAu) 2 Te 
 [Speculite AgAuTe] 
 Sylvanite AgAuTej 
 
 IRON 
 
 Hematite Fe 2 O 3 
 
 [Histrixite CusFesBiuSb^s? (mixture) J 
 
 Ilmenite FeTiO 3 
 
 Limonite 2 Fe 2 O 3 -3 H 2 O 
 
 Lollingite FeAs 2 
 
 Magnetite Fe 3 O 4 
 
 Marcasite FeSis 
 
 Pentlandite (FeNi)S 
 
 Polytelite (PbAgFeZn) 4 Sb J S7 ? 
 
 Pyrite FeS 
 
 Pyrrhotite FeS(S) z 
 
 [Richmondite R 6 Sb 2 S9 (R= Pb, Cu, Ag, Fe, 
 
 Zn)] 
 
 Stannite (Sn, Cu, Fe, Zn), S 
 Sternbergite Ag 2 Fe5S 
 Stylotypite (Cu 2 Ag 2 Fe) 3 Sb 2 S 
 [Troilite FeS] 
 
160 
 
 MICROSCOPICAL DETERMINATION 
 
 LEAD 
 
 PbAg 2 Sb 2 S 5 ? 
 
 Aikinite PbCuBiSa 
 
 Altaite PbTe 
 
 Andorite 
 
 Baumhauerite 
 
 Beegerite PbBi 2 S 9 
 
 Boulangerite 
 
 Bournonite 
 
 Brogniardite 
 
 Chiviatite 
 
 Clausthalite PbSe 
 
 Cosalite Pb 2 Bi 2 S 6 
 
 Cuprodescloizite (PbZnCu) 4 V 2 O 8 -H 2 O 
 
 Cylindrite 3 PbSnS 2 + SnFeSbaSs 
 
 [Diaphorite (PbAg 2 ) 6 Sb 4 Su] 
 
 Dufrenoysite Pb 2 As 2 S6 
 
 Epiboulangerite Pb 3 Sb 2 S 8 
 
 Frankeite 3 PbSnS 2 + PbzFeSbaSs 
 
 Freieslebenite (PbAg 2 ) 6 Sb 4 Su 
 
 Galena PbS 
 
 Galenobismutite PbBi 2 S 4 
 
 Geocronite PbsSbizSg 
 
 Guitermannite PbsAs 2 Se 
 
 [Hutchinsonite Tl, Ag, Cu, Pb, As, S ?] 
 
 Jamesonite P^SbaSs 
 
 Jordanite Pb 4 As 2 S? 
 
 Kobellite Pb 2 (BiSb) 2 S 6 (mixture?) 
 
 Lehrbachite PbSe + HgSe 
 
 Lengenbachite Pb 6 (AgCu) 2 As4S 1 3 
 
 Lillianite Pb 3 Bi 2 S 6 
 
 [Liveingite PbsAssSn] 
 
 Meneghinite 
 
 Nagyagite 
 
 Naumannite (Ag 2 Pb)Se 
 
 Plagionite PbsSbsSn 
 
 [Platynite PbBizSs] 
 
 Polytelite (PbAgFeZn) 4 Sb 2 S7 ? 
 
 Rathite Pb, As, Sb, S ? 
 
 Rezbanyite Pb 4 Bi 10 Si9 
 
 [Richmondite ReSbizSg (R= Pb, Cu, Ag, Fe, 
 
 Zn)] 
 
 Sartorite PbAs 2 S 4 
 Schapbachite PbAg 2 Bi 2 S 5 (mixture) 
 Schirmerite (Ag 2 Pb) 3 Bi 4 S9 
 Seligmannite CuPbAsS 3 
 Semseyite Pb 2 Sb 6 S 16 
 Steinmannite Pb(As, Sb, S) 
 Teallite PbSnS 2 
 
 Uraninite U, O, Pb, La, Th, Di, Y, etc. ? 
 [Weibullite Pb 2 Bi 4 S 6 Se 3 ] 
 Zinkenite PbSb 2 S 4 
 
 MANGANESE 
 
 Alabandite MnS 
 Erythrozincite (MnZn)S ? 
 Franklinite Fe 3 ZnMn 3 O 4 
 
 Hauerite MnS 2 
 Psilomelane H 4 MnOs 
 [Sampsonite ( Ag 4 Mn) Sb 2 S 6 ] 
 
 Cinnabar HgS 
 Coloradoite HgTe 
 Kalgoorlite HgAu 2 AgeTee 
 Lehrbachite PbSe + HgSe 
 
 MERCURY 
 
 Livingstonite HgSb 4 S? 
 Metacinnabarite HgS 
 Onofrite Hg(SSe) 
 Tiemannite HgSe 
 
 MOLYBDENUM 
 
 Molybdenite MoS 2 
 
 NICKEL 
 
 [Badenite (CoNiFe) 2 (AsBi)j] 
 Breithauptite NiSb 
 Chloanthite NiAs 2 
 Gersdorffite NiAsS 
 Hauchecornite (NiCo) 7 (Bi, S, Sb) 8 
 Kallilite NiBiS(AsSb) 
 Maucherite NisAsj 
 Melonite NizTei 
 
 Millerite NiS 
 Niccolite NiAs 
 Pentlandite (FeNi)S 
 Polydymite Ni^j 
 Rammelsbergite NiAsz 
 Ullmannite NiSbS 
 Willyamite (CoNi)SbS 
 
OF THE OPAQUE MINERALS 
 
 161 
 
 OXYGEN 
 
 Cassiterite SnO 2 
 
 Chromite FeCr 2 O4 
 
 Cuprite Cu 2 O 
 
 Cuprodescloizite (PbZnCu)4VjO-HO 
 
 Delafossite Cu, Fe, O * 
 
 Franklinite FesZnMnaCh 
 
 Hematite Fe 2 O 3 
 
 Ilmenite FeTiOs 
 
 Kennesite SbzSjO 
 
 Limonite 2 Fe 2 O 3 -3 HjO 
 
 Magnetite FesO4 
 
 Psilomelane H4MnOe 
 
 Rutile TiO 
 
 Tenorite CuO 
 
 Uraninite U, O, Pb, La, Th, Di, Y, etc. ? 
 
 Voltzite 
 
 Sperrylite PtAsz 
 [Laurite RuAs 2 ] 
 
 PLATINUM 
 
 RUTHENIUM 
 
 SELENIUM 
 
 Aguilarite Ag 2 S-Ag 2 Se 
 Berzelianite Cu 2 Se 
 Clausthalite PbSe 
 Crookesite (CuTlAg) 2 Se 
 Eucairite (CuAg) 2 Se 
 Guanajuatite Bi 2 Se 3 
 
 Lehrbachite PbSe + HgSe 
 Naumannite (Ag 2 Pb)Se 
 Onofrite HgSSe 
 Tiemannite HgSe 
 Umangite Cu 3 Se 2 
 [Weibullite 
 
 SILVER 
 
 Aguilarite Ag 2 S-Ag 2 Se 
 
 Andorite Pb 2 Ag 2 SbeS9 
 
 Argentite Ag 2 S 
 
 [Argentopyrite Ag, Fe, S ?] 
 
 Argyrodite AgeGeSs 
 
 Argyropyrite Ag, Fe, S, As ? 
 
 Brogniardite PbAg 2 Sb 2 S 6 ? 
 
 Calaverite AgAuTe 2 
 
 [Canfieldite Ag 8 (SnGe)S 8 ] 
 
 Chilenite AgeBi 
 
 Crookesite 
 
 [Diaphorite 
 
 Dyscrasite AgeSb 
 
 Eucairite (CuAg) 2 Se 
 
 Freieslebenite (PbAg 2 ) 5Sb4Su 
 
 Freibergite (CuAg^bsSi 
 
 Frieseite, AgFe 2 S 3 
 
 Hessite Ag 2 Te 
 
 Huntilite AgsAs ? 
 
 [Hutchinsonite Tl, Ag, Cu, Pb, As, S ?1 
 
 Jalpaite 3 Ag2S-Cu 2 S 
 
 Kalgoorlite HgAu 2 Ag 6 Te 6 
 
 Lengenbachite 
 
 Matildite AgBiS 2 
 
 Miargyrite AgSbS 2 
 
 Naumannite (Ag 2 Pb)Se 
 
 Pearceite AgAsS 
 
 Petzite (AgAu) 2 Te 
 
 Plenargyrite AgBiS 2 ? (mixture) 
 
 Polyargyrite Ag 24 Sb 2 Si S 
 
 Polybasite Ag 9 SbS 6 
 
 Polytelite (PbAgFeZn) 4 Sb 2 S7 ? 
 
 Proustite AgsAsSs 
 
 Pyrargyrite AgsSbSs 
 
 [Pyrostilpnite Ag 3 SbS 3 ] 
 
 [Richmondite R 6 Sb 2 S 9 (R = Pb, Cu, Ag, Fe, 
 
 Zn)] 
 
 [Sampsonite (Ag 4 Mn)Sb 2 S 6 ] 
 Schapbachite PbAg 2 Bi 2 S 5 (mixture) 
 Schirmerite (Ag 2 Pb) 3 Bi4S 
 Silver Ag 
 [Smithite AgAsS 2 ] 
 [Speculite AgAuTe] 
 Stephanite Ag 5 SbS 4 
 Sternbergite Ag 2 FesS3 
 Stromeyerite (AgCu)^ 
 Stutzite Ag 4 Te ? 
 Stylotypite (Cu 2 Ag 2 Fe) 3 SbS, 
 Sylvanite AuAgTe 2 
 Tapalpaite 3 Ag 2 (STe)-Bi 2 (STe) 8 
 [ Trechmannite AgAsS 2 ] 
 [Von Diestite Ag, Bi, Te ?] 
 [Xanthoconite AgsAsS4] 
 
162 MICROSCOPICAL DETERMINATION 
 
 TELLURIUM 
 
 Altaite PbTe Rickardite Cu 4 Tes 
 
 Calaverite AgAuTej [Speculite AgAuTe] 
 
 Coloradoite HgTe Stiitzite Ag 4 Te ? 
 
 [Grttnlingite Bi4TeS 8 ?J Sylvanite AuAgTe 2 
 
 Hessite Ag 2 Te Tapalpaite 3 Ag 2 (STe)-Bi 2 (STe)8 
 
 Kalgoorlite HgAu2AgTe Tellurium Te 
 
 Melonite Ni 2 Te 3 Tetradymite Bi 2 (TeS)s 
 
 Nagyagite Au 2 PbioSb 2 TeSi5 [Von Diestite Ag, Bi, Te ?J 
 Petzite (AgAu) 2 Te 
 
 THALLIUM 
 
 Crookesite (CuTlAg) 2 Se Lorandite TlAsS 
 
 [Hutchinsonite Tl, Ag, Cu, Pb, As, S ?] Vrbaite TlAs 2 SbS 6 
 
 THORIUM 
 
 (with Lanthanum, Yttrium, Nitrogen, etc.) 
 Uraninite U, O,'Y, N, Di, Th, La, etc. 
 
 TIN 
 
 " Bronze Enargite" (CuSn), (SbAs), S ? Stannite Sn, Cu, Fe, Zn, 8 
 
 Cassiterite SnO 2 Teallite, PbSnS 2 
 
 Cylindrite 3 PbSnS 2 + SnFeSb 2 Ss [Canfieldite Ag8(SnGe)S 6 ] 
 Frankeite 3 PbSnSj + Pb 2 FeSb 2 S8 
 
 I TITANIUM 
 
 Ilmenite FeTiOi Rutile TiOj 
 
 URANIUM 
 
 Uraninite U. O, Pb, Y, N, Di, La, Th, etc. 
 
 VANADIUM 
 
 Cuprodescloizite (PbZnCu) 4 V 2 O-H 2 O Sulvanite 
 
 [Patronite VS 4 ? ] 
 
 ZINC 
 
 Cuprodescloizite (PbZnCu) 4 V 2 O 9 -H 2 O Sphalerite ZnS 
 
 Erythrozincite (ZnMn)S ? Stannite Sn, Cu, Fe, Zn, S 
 
 Franklmite FesZnMr^ Voltzite Zn8S 4 O 
 
 Polytelite (PbAgFeZ^^bzST Wurtzite ZnS 
 (Richmondite RaSb 2 S 9 (R = Pb, Cu, Ag, Fe, 
 Zn)] 
 
INDEX OF MINERALS 
 
 The number in parentheses after each name indicates the number 
 of localities from which material has been studied, (n) indicates 
 more than 5 localities. The letter or symbol, in the case of single 
 specimens, indicates the probable value of the specimen as a repre- 
 sentative of its species. G = reliable. F = fairly reliable. ? = 
 doubtful. 
 
 MINERAL 
 
 Aguilarite (1) G 
 
 Aikinit.fi (1) G 
 
 Alabandite (3) 
 
 Algodonite (mixture) (1) . 
 
 Cream constituent 
 
 Gray constituent 
 
 Alloclasite (mixture ?) (1) 
 
 Altaite (3) 
 
 Andorite (1) G 
 
 Animikite (mixture ?) (1). 
 
 Argentite (4) 
 
 Argyrodite (2) 
 
 Argyropyrite (1) ? 
 
 Arsenic (2) 
 
 Arsenopyrite (n) 
 
 PAGE 
 
 10A 
 
 101 
 
 96 
 
 37 
 
 74 
 
 96 
 
 37 
 
 128 
 
 134 
 
 37 
 
 107 
 
 105 
 
 101 
 
 136 
 
 82 
 
 Barnhardtite (mixture) (1) 
 
 Baumhauerite (1) G 
 
 Beegerite (1) G 
 
 Berthierite (3) 
 
 Beraelianite (1) G 
 
 Bismuth (n) 
 
 Bismuthinite (3} 
 
 Antimonial (1) G 
 
 Bornite (n) 
 
 Boulangerite (2) 
 
 Bournonite (4) 
 
 Breithauptite 
 
 Brogniardite (1) ? 37, 
 
 Calaverite (1) G 
 
 Carrollite (mixture ?) (1) 
 
 Gassiterite (3) 
 
 Chalcocite (n) 
 
 Chalcopyrrhotite (mixture) (1) 
 
 Chalcostibite (1) G 
 
 Chalcopyrite (n) 
 
 Chalmersite (3) 
 
 Ctolenite (1) G 
 
 Chiviatite (1) G 
 
 Chloaathite (2) 
 
 37 
 108 
 134 
 103 
 131 
 125 
 130 
 131 
 
 65 
 135 
 
 92 
 
 66 
 110 
 
 124 
 
 37 
 
 146 
 
 107 
 
 37 
 
 102 
 
 62 
 
 72 
 
 125 
 
 120 
 
 85 
 
 MINERAL 
 
 PAGE 
 
 Chromite (2) 146 
 
 Cinnabar (2) 141 
 
 Clausthalite (1) G 128 
 
 Cobaltite (2) 86 
 
 Coloradoite (1) G 106 
 
 Copper (n) 67 
 
 Cosalite (1) F 122 
 
 Covellite (n) 58 
 
 Crookesite (1) F 108 
 
 Cubanite (mixture) (4) 37 
 
 Cuprite (n) 117 
 
 Cuprodescloizite (1) G 149 
 
 Cylindrite (1) G 110 
 
 Delafossite (1) G 92 
 
 Dognacskaite (1) G 135 
 
 Domeykite (2) 37, 125 
 
 Dufrenoysite (1) G 142 
 
 Dyscrasite (2) 125 
 
 Emplectite (3) 122 
 
 Enargite (n) 95 
 
 Epiboulangerite (1) G 134 
 
 Erythrozincite (1) G 148 
 
 Eucairite (1) G 130 
 
 Famatinite (3) ? 99 
 
 Frankeite (1) G 110 
 
 Franklinite (1) G 144 
 
 Freibergite (2) 94 
 
 Freieslebenite (1) G 134 
 
 Galena (n) 133 
 
 Galenobismutite (1) ? 130 
 
 Geocronite (1) F 132 
 
 Gersdorffite (2) 88 
 
 Glaucodot (1) G 87 
 
 Gold (n) 62 
 
 Guanajuatite (1) G 120 
 
 Guejarite (1) G 103 
 
 Guitermanite (1) G 134 
 
 163 
 
164 
 
 MICROSCOPICAL DETERMINATION 
 
 MINERAL 
 
 PAGE 
 
 Harrisite (pseudomorph) (1) G 38 
 
 Hauchecornite (2) 79 
 
 Hauerite (2) 94 
 
 Hematite (n) 90 
 
 Hessite (2) 138 
 
 Homichlin (mixture) (1) G 38 
 
 Horsfordite (1) G 135 
 
 Huntilite (1) F 119 
 
 Ilmenite (5) 90 
 
 Jalpaite (1) F 140 
 
 Jamesonite (2) 110 
 
 Jordanite ? (1) ? 134 
 
 Kalgoorlite (1) G 124 
 
 Kallilite (1) F 82 
 
 Kermesite (1) G 138 
 
 Keweenawite (mixture) (2) 38 
 
 Klaprotholite (mixture ?)(!)? 38 
 
 Kobellite 38 
 
 Krennerite (1) G 124 
 
 Lehrbachite (1) F 131 
 
 Lengenbachite (1) G 141 
 
 Lillianite (1) G 133 
 
 Limonite (n) 146 
 
 Linnaeite (2) 79 
 
 Livingstonite (1) G 142 
 
 Lollingite (2) 84 
 
 Lorandite (1) G 150 
 
 Luzonite (3 ?) 98 
 
 Magnetite (n) 91 
 
 Marcasite (n) 78 
 
 Matildite (1) G 140 
 
 Maucherite (2) 79 
 
 Melonite (1) G 124 
 
 Meneghinite (1) G 132 
 
 Metacinnabarite (1) G 122 
 
 Miargyrite (1) G 115 
 
 Millerite (3) 63 
 
 Mohawkite (mixture) (1) G 38 
 
 Cream constituent 74 
 
 Gray constituent 97 
 
 Molybdenite (4) 104 
 
 Nagyagite (2) 134 
 
 Naumannite (1) G 128 
 
 Niccolite (n) 66 
 
 Onofrite (1) F 114 
 
 Orpiment (2) 105 
 
 Pearceite (1) F 105 
 
 Pentlandite (1) G 100 
 
 Petzite (2) 137 
 
 Plagionite (1) G 135 
 
 Plenargyrite (mixture) (1) F 38 
 
 Hard constituent 136 
 
 Soft constituent 116 
 
 Polyargyrite (1) G 114 
 
 MINERAL PAGE 
 
 Polybasite (3) 105 
 
 Polydymite (2) 82 
 
 Polytelite (1) ? 96 
 
 Proustite (n) 115 
 
 Psilomelane (2) 144 
 
 Pyrargyrite (6 ?) 115 
 
 Pyrite (n) 78 
 
 Pyrrhotite (n) 76 
 
 Rammelsbergite (1) G 85 
 
 Rathite (1) G 141 
 
 Realgar (3) 108 
 
 Regnolite (1) G 104 
 
 Rezbanyite (1) G 136 
 
 Rickardite (1) G 60 
 
 Rutile (2) 90 
 
 Safflorite (1) G 83 
 
 Sartorite (1) F 142 
 
 Schapbachite (mixture) (1) F 38 
 
 Hard constituent 137 
 
 Soft constituent 116 
 
 Schirmerite (1) F 141 
 
 Seligmannite (1) G 104 
 
 Semseyite (1) G 132 
 
 Silver (n) 118 
 
 Skutterudite (1) ? 83 
 
 Smaltite (3) 38, 83 
 
 Sperrylite (1) G 91 
 
 Sphalerite (n) 148 
 
 Stannite (3) 108 
 
 Steinmannite (var. Galena) (1) G 133 
 
 Stephanite (2) . 142 
 
 Sternbergite (1) G 65 
 
 Stibnite (3) 138 
 
 Stromeyerite (3) 117 
 
 Stutzite (1) G 114 
 
 Stylotypite (1) F 97 
 
 Sulvanite (1) G 72 
 
 Sylvanite (2) 122 
 
 Tapalpaite (mixture ?) (1) G 38, '125 
 
 Teallite (1) G 106 
 
 Tellurium (3) 130 
 
 Temiskamite (mixture) (1) G 38 
 
 Tennantite (n) 94 
 
 Tenorite (2) 92 
 
 Tetradymite (2) ? 133 
 
 Tetrahedrite (n) 94 
 
 Tiemannite (1) G 114 
 
 Ullmannite (1) G 84 
 
 Umangite (3) 60 
 
 Unknown minerals: 
 
 Algodonite cream 74 
 
 gray 96 
 
 " Alloklas" from Orawitaa 136 
 
 Argentiferous "Jamesonite" 104 
 
OF THE OPAQUE MINERALS 
 
 165 
 
 MINERAL 
 
 PAGE 
 
 4 'Brogniardite" (near andorite) .... 134 
 
 Bluish white, Joachimsthal 115 
 
 Bluish white, Tonopah r/ . 114 
 
 " Bronze Enargite " ; . . . . 74 
 
 Coffee brown ^ . 65 
 
 Creamy bismuth minertd 126 
 
 Grayish bismuth mineral 97 
 
 "Hessite" 118 
 
 " Matildite" Japan 120 
 
 Mohawkite cream 74 
 
 gray 97 
 
 Orange " bornite" 64 
 
 "Petzite" 106 
 
 Pink mineral in mohawkite 76 
 
 Purple "bornite" 65 
 
 Purple "galena" 116 
 
 MINERAL PAGE 
 
 Plenargyrite, hard constituent 136 
 
 Soft constituent 116 
 
 Schapbachite, hard constituent 137 
 
 Schapbachite, soft constituent 116 
 
 " Tapalpaite" Gray 107 
 
 Pure white mineral, Bisbee 130 
 
 Uraninite (1) G 147 
 
 Voltzite (1) G 148 
 
 Vrbaite (1) G 115 
 
 Whitneyite (1) G 74 
 
 Willyamite (1) G 82 
 
 Wittichenite (1) F 121 
 
 Wurtzite (1) G 148 
 
 Zinkenite (2) Ill 
 
f ; 
 A 
 
34024? 
 
 UNIVERSITY OF CALIFORNIA LIBRARY 
 

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