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MICROSCOPIC EXAMINATION
OF
THE ORE MINERALS
MeGraw-Hill Book Cane
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MICROSCOPIC EXAMINATION
OF
THE ORE MINERALS
BY
'W. MYRON DAVY
AND
C. MASON FARNHAM
FIRST EDITION
MCGRAW-HILL BOOK COMPANY, INC.
NEW YORK: 239 WEST 39TH STREET
LONDON: 6 & 8 BOUVERIE ST., E. C. 4
1920
COPYRIGHT, 1920, BY THE
McGRAW-HILL BOOK COMPANY, INC.
THE DIAPLE PRESS YORK PA
INTRODUCTION
The use of the reflecting microscope as a means of determining
the identity, relationship, and significance of opaque minerals in
ore deposits has been steadily increasing since William Campbell, 1
in 1906, first applied the methods then used by metallographers
in the study of metals, to the examination of opaque minerals.
Nearly a century ago Berzelius published the results of polishing
a specimen of pyrrhotite and suggested the possibilities of exam-
ining opaque minerals in this way, but no practical methods
resulted from his observations at that time. Even after Camp-
bell's paper, mining and geological literature did not reflect any
great interest in the subject until six or seven years had passed,
when some admirable papers described the studies on particular
types of ores. About this time the laboratories of mining geology
at the Massachusetts Institute of Technology, Harvard Univer-
sity, and Leland Stanford University, as well as a few other in-
vestigators, were carrying on extensive researches in this field of
study. In 1916, Dr. Joseph Murdoch? published the results of
numerous microchemical tests, arranging them in a determinative
table which was by far the most complete work on identification
of minerals under the metallographical microscope, and his book
deserves the credit for much valuable pioneer work. Several
years have now passed and new ideas have originated as the result
of further study along this line.
Work carried on steadily in the laboratories at the Massachu-
setts Institute of Technology on a wide range of ores, and at
Harvard University on the original collection of minerals that
formed the basis of Dr. Murdoch's book, justifies the following
conclusions:
1. Fine distinctions in color value between the many so-called
white minerals cannot be depended upon as a safe property on
which to base the major classifications in making identity deter-
minations. It has been found that hardly any two persons can
1 CAMPBELL, W. "The Microscopic Examination of Opaque Minerals."
Economic Geology, Vol. 1, 1906, p. 751.
2. MURDOCH, J. “Microscopical Determination of the Opaque Minerals.”
Preface by L. C. GRATON, John Wiley & Sons. 1916.
V
vi
INTRODUCTION
agree in the application of such terms as bluish white, pinkish
white, creamy white, purplish white, etc. However, if two
microscopes and a comparison eyepiece are used, or if a standard
mineral can be mounted adjacent to the unknown, most observers
will agree in pronouncing the unknown to be lighter, darker, or
the same as the stardard; but at best this method is awkward,
especially when the unknown mineral does not occur on the
edge of the section. Some minerals change color after polish-
ing, the kind of light used effects the colors seen, and a few
cases have been observed where two freshly polished specimens
of the same mineral differed so greatly in color as to fall into
widely separated groups. The observed color of a mineral may
be greatly influenced by the colors of other minerals in the field,
for example, chalcopyrite is yellow when seen alone, but if seen
adjacent to native copper it will appear to be a decided olive
green. For these reasons the scheme of identification used in
this book is independent of color distinctions which are only used
in conjunction with many other properties as an ultimate means
of separating the different minerals that fall into a final group.
2. Detailed descriptions of the way in which microchemical
reactions proceed are in many cases valueless because of the fact
that two specimens of the same mineral seldom yield exactly
identical results. In nearly every case, however, they will check
as far as reacting positively or negatively with a reagent is con-
cerned, which is all that is needed for identification. Moreover,
it has been found that slight differences in the character of the
mineral surface, slight differences in the concentrations of the
reagents, and sometimes even the crystallographic orientation
of the polished section have an important influence upon the
reactions.
3. The number of reagents which can be used advantageously
throughout a determinative scheme is limited to four or five.
Many others have been tried, but their application is very limited
and as time goes on the tendency is more and more toward
simplification. In this work no attempt is made to list all tests
known to date, but only those supplementary ones are included
which may be valuable in differentiating between two or more
minerals falling in one final group. As emphasized in the fol-
lowing paragraph, in most cases an easily applied blowpipe test is
convenient and adds far more confidence to the determination.
4. As in the early application of new developments in all lines,
INTRODUCTION
vii
mineragraphy has been pushed beyond its natural limitations in
displacing other determinative methods and now a slight reaction
is setting in. This art gives us our most useful means for ex-
amining into the genesis of ore deposits, and is in itself a very
valuable method of mineral determination; in certain cases, the
best known method. But in the determination of the minerals in
an average polished section of ore it is a handicap to restrict the
examination to mineragraphic tests alone. One of a group of
possible minerals can usually be run down quickly and confi-
dently by gouging out from the edge of the section a small piece
seen to contain the unknown, and treating it on charcoal before
the blowpipe, or heating it in the open or closed tube, etc. The
objection has been raised that the unknown cannot be cleanly
separated, but very often all the other minerals are known and
the reactions yielded by them can usually be discounted. There
is never any need to run through a blowpipe analysis as the micro-
chemical reactions narrow the possibilities down to a few min-
erals, and one or two tests suffice. Consequently it has been
found exceedingly helpful to include the characteristic blowpipe
reactions for each mineral along with its other properties in the
tables.
The foregoing considerations have largely influenced the ar-
rangement of the tables and the choice of the material to be
included in them.
The microchemical reactions listed are from various sources.
The authors have independently studied one hundred and forty-
three mineral species, thus covering all except a few of the rarest
varieties; and as most of these species are also listed in Dr. Mur-
doch's book, it is believed that this triple check results in the
accurate determination of the reactions.
Fourteen minerals not previously described in mineragraphy
have been tested and included in this work. A few very rare
and doubtful species and some mixtures described by Murdoch
have been omitted as it is felt that their presence in the tables
complicates and adds little of practical value for the average
The impression must not be gathered, however, that the
so-called rare minerals are unimportant for, although only the
more common minerals are encountered in nine out of ten ores
examined, it is of great importance to recognize the rarer ones
when they do occur. Furthermore, these uncommon minerals
are sometimes found in small quantities or as fine intergrowths
user.
viii
INTRODUCTION
and their presence is never suspected until examined micro-
scopically with vertical illumination; consequently they become
less rare and take on a greater importance in mineragraphic
study than has been the case with former mineralogical methods.
Mineragraphy is used throughout the book to designate the
art of polishing, identifying, and examining the ore minerals
under the metallographic microscope. Minera is late Latin
meaning ore and graphy has been borrowed from the well esta-
blished metallography. Whitehead' first used this name in print,
and although mineragraphy as a word is not altogether pleasing,
a name is much needed and it is here used with the hope that
something better will be suggested.
It is believed that an infallible determinative table has never
been devised on any subject, and the task is even more difficult
in this case where the available material is at best new and little-
tried. The beginner, of course, must acquire familiarity with
both the tables and the general appearance under the micro-
scope of the more common minerals, and even the experienced
mineralogist must serve a short apprenticeship in order to
obtain good results. In preparing this book it was felt that a
text was needed which could be used by both the profession and
the student of mining and geology. Communications addressed
to the laboratories of economic geology of the Massachusetts
Institute of Technology indicate that the study of ore minerals
in reflected light is to be introduced into the curriculum of
several more of the country's larger institutions, and that a
statement of the latest practice was desired. It is hoped that
this rather brief review of the subject will serve such a practical
purpose until such time as the combined experience and dis-
coveries of many workers greatly increase our present knowledge
along this line.
The authors wish to express their appreciation to Professor
Waldemar Lindgren whose able and patient guidance has made
the book possible, and to Professor L. C. Graton whose keen
interest in this work has ever been a helpful inspiration.
1 WHITEHEAD, W. L. “Notes on the Technique of Mineragraphy.”
Economic Geology, Vol. xii, No. 8, 1917, p. 697.
TABLE OF CONTENTS
PAGE
V
INTRODUCTION.
Previous work-Color an unreliable determinative factor-Lack of
consistency in reactions--Advantages of employing few reagents
in the tables-Necessity for utilizing all determinative means-
Range of material examined-Definition of mineragraphy
Acknowledgments.
CHAPTER I
1
TECHNIQUE OF POLISHING AND EXAMINING THE SPECIMEN.
Necessity for specialized polishing methods—Grinding-Polishing
-Field preparation of a specimen by hand-Examination of the
specimen-Microscope used-Optical principle involved-Con-
struction and use of finder—Method of applying tests Electrical
conductivity of minerals-Electropotential of minerals—Concen-
tration of reagents.
CHAPTER II
12
PHOTOMICROGRAPHY OF POLISHED SECTIONS.
Equipment–Need for color filters-Methods of determining proper
exposure-Exposure curves-Developing and printing.
CHAPTER III
20
USE OF THE DETERMINATIVE TABLES..
Procedure in making determinations-Abbreviations used in tables
- Outline of the tables-Determinative tables.
CHAPTER IV
.
SUPPLEMENTARY TESTS...
120
Tabular arrangement of the minerals according to: Color of surface;
Color of internal reflection; Color of powder; Electrical conduc-
tivity; Electro-potential—Tests for the elements with minerals
arranged according to elements-Mirochemical qualitative re-
actions-Standard fusibilities--Heating on charcoal-Sublimates
in the closed tube-Sublimates in the open tube-Bead colors with
borax and salt of phosphorous.
INDEX.
.. 151
ix
MICROSCOPIC EXAMINATION
OF
THE ORE MINERALS
CHAPTER I
TECHNIQUE OF POLISHING AND EXAMINING THE
SPECIMEN
Preparation of the Specimen
The successful determination of the identity of minerals
with the reflecting microscope depends primarily upon having all
minerals in the section properly polished with little relief, free
from scratches, pits, and vugs; and without having changed the
chemical character of delicate sulphides during the grinding
process. It has been observed, for example, that chalcopyrite
if ground under pressure on a rapidly revolving dry lap will
develop bornite and chalcocite; and that pyrite when treated
likewise will develop limonite.
In 1917 W. L. Whitehead1 pointed out the fact that minera-
graphic sections require grinding and polishing treatment funda-
mentally different from that of metals for metallographic study.
A metal specimen is usually one of uniform hardness and possesses
far more ductility and toughness than an ore section which often
consists of several minerals of widely differing hardness and of
more or less brittleness. Pyrite, a mineral harder than almost
any metal, is so universally present in ores that it often must
be polished in the same section with a mineral so soft as to be
scratched by the finger nail. When purely metallographic
methods are used in polishing ores this difference in hardness
presents formidable difficulties to good work. The soft broad-
cloth surface of the wheel swells outward and rapidly wears down
the soft minerals, developing a relief so pronounced that it is
1 WHITEHEAD, W. L. “Notes on the Technique of Mineragraphy."
Economic Geology, Vol. xii, No. 8, 1917, p. 697.
1
2
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
impossible to focus upon two adjacent soft and hard minerals,
especially at high magnifications.
In the laboratory, specimens are usually desired for two dis-
tinct purposes; first, for visual examination and second, for
photomicrographs. Comparatively little effort is required in
polishing sections for the former purpose, and while a badly
scratched and pitted surface should never be tolerated, very fine
and shallow scratches do not interfere with visual study at any
magnification. However, these comparatively minute scratches
and pits make photography difficult, and they require exhaustive
and careful polishing for their elimination.
The following procedure is in use at the Massachusetts In-
stitute of Technology and with minor variations can easily be
adapted to any grinding and polishing equipment. First, a
portion of the specimen is chosen which appears to represent all
the important features present, an area of a square inch or less
usually being sufficient. This may be carefully chipped or cut
off with a diamond saw. The latter method is by far the best
when such equipment is available, as it rapidly yields an approxi-
mately plane surface at any desired orientation and the opposite
face of the cut can be made into a thin section if required. The
saw used is 10 inches in diameter and is driven at 1600 R.P.M.
Any large inequalities in the surface chosen should be re-
moved by grinding wet upon a steel lap wheel with 150 emery
or alundum. A 10-inch horizontal wheel revolving at about
200 or 225 R.P.M. is used. After thorough washing of the hands
and specimen the grinding is continued on an 8-inch horizontal
glass wheel driven at 1800 R.P.M. and using the finest optical
alundum (manufactured by Norton & Co., Worcester, Mass.)
mixed to a very thin slime with water. This is perhaps the
most important stage in the preparation. Considerable pressure
may be exerted at first to quickly remove the scratches caused
by the coarse abrasive; then grinding should be continued with
light pressure until the surface is free of all except very fine
scratches and pits. More than a minute or two is seldom re-
quired at this stage, but when needed more time should be
taken, as a minute spent here saves ten minutes later.
The true grinding part of the operation is completed and from
now on the purpose of the work is to obtain a final polish. The
same preparation of finest optical alundum is next used on a high
speed 8-inch wheel covered with tightly stretched coarse linen
POLISHING AND EXAMINING THE SPECIMEN
3
(about 15 threads per cm.). This wheel is horizontal and is
driven at 1800 R.P.M. The specimen should be lightly held
and constantly turned for 30 to 60 seconds, finishing up with
about 30 seconds polishing without applying fresh alundum.
The abrasive breaks down and developes a fine polish as seen
by the naked eye.
This polish is improved by holding lightly for 30 or 60 seconds
on a similar wheel covered with fine linen (30 threads to the cm.)
using a slime of rouge and water. This wheel is an 8-inch hori-
zontal lap wheel driven at 1000 R.P.M. After thorough wash-
ing and drying the final surface is obtained on a wheel similar
to the preceding, but covered with tightly stretched calf skin.
A split calf skin with the grease removed and finished with a
very short nap on the flesh side is used. Care should be taken
here to prevent overheating with consequent altering of the
sulphides and burning of the leather. With a little practice
10 minutes will suffice for the entire process of cutting and polish-
ing a surface comparatively free from scratches and trouble-
some relief, which can be satisfactorily studied even under the
highest magnifications.
Out of a number of specimens studied from one deposit, two
or three will usually be chosen for photographing, and these
should receive additional preparation to eliminate the very fine
scratches which cannot be avoided with the foregoing procedure
alone. Chromic oxide has been found to yield the best results
of all materials tried to date. Its use is introduced between the
second optical alundum and the rouge wheels. The finest com-
mercial chrome oxide is levigated to remove any coarse material
and is used on a coarse linen wheel revolving at 1800 R.P.M. or
faster. Careful treatment here eliminates the fine scratches pro-
duced by the optical alundum. The specimen, as before, is
finished on the rouge wheel.
In discussing a method of polishing ore specimens no fixed rule
can be formulated and the more work that is done the more evi-
dent it becomes that each type of ore requires specialized treat-
ment to obtain the best surface for photography. On the other
hand, as previously stated, only a small portion of the specimens
studied need be so prepared and the standardized and rapid
method first described produces excellent results when only visual
studies are to be made.
The quality of the illustrations in many of the recent papers
4
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
on mineragraphic study proves that some of the laboratories
have highly developed polishing methods and criticisms and sug-
gestions from them should advance our knowledge of the subject.
FIELD PREPARATION OF A SPECIMEN BY HAND
The engineer studying or developing a prospect, or the geol-
ogist in the field usually lacks the necessary equipment as above
described, yet it is often important and helpful to clear up certain
points without waiting until the apparatus is available. In this
case fairly satisfactory results can be obtained by hand with a
supply of coarse and fine emery or alundum, rouge and leather.
They should all be used on surfaces similar to those described
under mechanical polishing methods. So valuable does this line
of investigation promise to become for the examining engineer
and geologist and so inexpensive is the microscopic equipment
necessary that a supply of the requisite materials should be a
part of every field outfit.
EXAMINATION OF THE SPECIMEN
A good microscope in common use is the Sauveur and Boyleston
metallographic microscope manufactured by the Bausch and
Lomb Optical Company, and illustrated in Fig. 1. It is very
convenient for examination in daylight and with moderate mag-
nifications. The objectives usually used are of the short mounted
type and are of 16 millimeters and 4 millimeters focal length.
Many types of microscopes, however, can be fitted with a vertical
illuminating prism and be used for ordinary mineragraphic pur-
poses. The simple optical principle involved is illustrated in
Fig. 1. Light enters at and is reflected vertically downward by
the prism, strikes the polished surface, and is reflected vertically
upward. A thin plane glass illuminator is used in place of the
prism at higher magnifications and with artificial illumination,
as it gives a sharper image. The plane glass reflector, however,
is unsuited for use with daylight as it does not give sufficient
intensity. Recently a silvered reflector to replace the prism has
been placed on the market and has proved satisfactory with all
kinds of light.
A devise that gives the location of any particular feature
in a polished section, and enables this feature to be brought
again immediately into the field of the microscope, may be
POLISHING AND EXAMINING THE SPECIMEN
5
easily constructed in a few minutes. (See Fig. 2.) A piece of
metric cross-section paper ruled to millimeters is sealed between
00
Capillary
Pipette-
-Reflection Prism
+ Path of Light
Polished Surface
illos
HNO3
CONC
0.
Section Mounting
Screw.Cup
Bell-Top Bottle
FIG. 1.
two thin pieces of glass which are about four and one-half centi-
meters long and two and one-half centimeters wide. (Glass slides
used in mounting thin sections may be used.) To the under
0
10
20
30
40
D
10
20
Finder
Polished Section
FIG. 2.
side, two narrow strips of wood are glued to two adjacent edges
so that their intersection will form a perfect right-angled corner.
The cross-section lines should be considered coördinate lines and
6
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
the point directly above the intersection of the wooden strips be
considered the 0-0 coördinate. It is necessary that two sides of
the polished section be ground so as to form a right-angled corner.
This rough grinding requires only a few minutes additional work
on the section, and the edges thus produced allow all minerals
at the edges to be compared directly with standard minerals.
In subsequent polishing, these sharp edges will not injure the
polishing cloth, provided the corner is pointed in the direc-
tion of revolution of the lap. When any feature in a polished
section is to be located; the procedure is as follows: (1) raise
the objective about a centimeter and gently place the finder
upon the polished section, carefully fitting the corner of the sec-
tion into the corner formed by the wooden strips on the finder;
(2) focus upon the glass surface of the finder, using the 16-mm.
objective, and place a minute drop of ink with a fountain pen in
the center of the field; and (3) remove the finder and read directly
the location as x millimeters to the right of, and y millimeters
down from the coördinate 0-0. Relocation is made in reverse
order. This method has been used on a large number of sections,
and though rather crude, has been found to be simple and effect-
ive, and almost indispensable with the highest magnifications.
The specimen is mounted by being pressed into a lump of
modelling clay on a glass slide or similar surface. The polished
surface must be perpendicular to the axis of the microscope and
probably the most convenient method of leveling it accurately
is by means of a screw bottom cup also illustrated in Fig. 1. A
piece of 2-inch pipe about 2 inches long is threaded on the inner
side and fitted with a threaded plug bottom. The slide with the
specimen pushed approximately level into the clay is placed in-
verted across the top of the cup. By adjusting the bottom the
slide is made to just clear the rim and it is then pushed firmly
down. The surface of the specimen is now parallel to the slide
which will rest upon the stage and consequently will be perpen-
dicular to the axis of the microscope.
For preliminary study and when applying reagents the 16
millimeter (low power) objective is always used. Focus upon
the surface to be examined and adjust the vertical illuminator
until the surface appears brightest. The opaque minerals will
appear white or colored, while the transparent gangue minerals
will be black or very dark gray. Tests for hardness, sectility,
color of powder, chemical behavior, etc., may now be applied.
POLISHING AND EXAMINING THE SPECIMEN
7
}
A fine sharp needle mounted in a small handle five or six inches
long will serve to test for hardness or similar properties. The
user should accustom himself to always holding it in about the
same manner when testing for hardness in order to correctly com-
pare results. Those minerals that scratch easily without pres-
sure or with very light pressure are classified as of low hardness;
those which scratch very slightly with light pressure or easily with
heavy pressure are classified as of medium hardness; and those
minerals which scratch very slightly or not at all with heavy pres-
sure are classified as of high hardness. The opaque minerals
range through a uniform gradation from the softest, to the hardest,
but after a short time it is not difficult to classify most of them
readily. When a mineral is on the border line between two
degrees of hardness it is usually found in both positions in the
tables.
Sectility or brittleness determination is another convenient
test which is sometimes of value. When testing for this property
the needle is pushed across the mineral surface with a rotary
motion; when the mineral is brittle the powder formed, if any,
usually flies away from the edge of the scratch; if the mineral is
sectile, little or no powder is formed and the needle penetrates
more or less as in cheese.
When a heavy scratch is made by pushing the needle point
across the mineral surface the color of the raised edge of the fur-
row or of the powder formed is very characteristic in the case of
certain minerals and this property is an important aid in identifi-
cation in these cases. See Table 9, page 122.
The microchemical tests are by far the most important
in identifying the minerals and should consequently be ap-
plied with care and uniformity. The reagents are conven-
iently applied to the polished surface by the use of a pipette with
a fine capillary opening fitted with a small rubber bulb. With
such a fine pipette a very small drop of the reagent can be applied
exactly where desired and great nicety of manipulation is easily
possible. It has been found desirable to use a bell top bottle in
which the pipette fits as a ground glass stopper, as the microscope
is thus guarded from the acid fumes. A method of applying the
reagents described by E. S. Bastin' has been found convenient
in some cases, especially with the weaker reagents. In this
method a small strip of blotting paper tapered at one end is used
1 Economic Geology, Vol. xi, No. 7, 1916, p. 691.
8
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
for touching the surface with the reagent and another clean strip
is used for removing it to stop the reaction when desired.
The tests should be watched under the microscope at all stages
and the following points observed: (1) Is any effervescence pro-
duced? (2) Does the surface change color? (3) Is there any
structure developed (cracks or cleavage, etc., made more promi-
nent)? (4) Do the fumes of the reagent affect the mineral sur-
face beyond the edges of the liquid ? After the reaction has
proceeded for ten seconds or up to a minute, depending upon
rate of attack, the specimen may be removed from the stage and
washed by directing a fine stream of water on the surface from a
small wash bottle or dropping tube. The section is again ex-
amined under the microscope without rubbing and the following
points noted: (1) Is the area covered by the liquid tarnished?
(2) Is there any structure or etching developed in this area? (3)
Is the area subjected to the fumes tarnished? The specimen is
again removed from the stage, carefully dried, and rubbed lightly
on a block covered with chamois skin, and again examined to
determine whether or not the effects are persistent. Before
rubbing, the surface is sometimes slightly dirty due to the evap-
oration of some of the liquid even though the reaction is entirely
negative. This should not be mistaken for a slight positive reac-
tion and may usually be avoided by carefully blotting the washed
surface with a soft handkerchief or cloth.
Electrical conductivity, in many instances, may serve to
distinguish minerals of similar physical and microchemical
properties. The test for electrical conductivity is made under
the microscope, using a 16-mm. objective, and the equipment
must be adapted to mineral surfaces as small as two millimeters
in diameter. Therefore steel needles had to be used for contacts.
At first it was thought that these contacts would have to be placed
a fixed distance apart in order to give constant readings, but
experiment has shown that the difference between having the
terminals a centimeter apart and very close together, is too small
to be recorded. The apparatus consists of two Columbia dry
cells No. 6, and a Weston D.C. voltmeter connected in series.
The voltmeter had a resistance of 251 ohms, and read 150 with
the circuit closed. As would naturally be expected the needle
points introduce additional resistance; and differences in read-
ings arise from varying pressure with which the points are
pressed upon the mineral surface, the fact that soft minerals
POLISHING AND EXAMINING THE SPECIMEN
9
allow the points to penetrate further tnan do hard minerals;
and that a rough surface will give a different reading from the
same surface when perfectly polished. This method is, there-
fore, qualitative rather than quantitative, but does serve to
arrange the minerals in a series in proper order, beginning with
those that do not conduct electricity, and ending with those that
conduct electricity as easily as copper. Only minerals that are
found widely apart in this series may be definitely distinguished
by this means. The mineral to be tested is brought into the
center of the field of the microscope, the two steel needle points
are placed upon the surface, and the voltmeter reading noted.
The mineral will immediately give either a reading of zero, of
150, or an intermediate reading; thus, giving at once three
groups: minerals apparently non-conductors, minerals with
conductivity equal to or greater than copper, and minerals
having electrical conductivity but with greater resistance than
copper. Minerals belonging to these three groups will be
found tabulated in Table 10, page 123. By this method
plagionite may be distinguished from galena, stromeyerite
from argentite, tennantite from tetrahedrite, pentlandite from
chalmersite, etc.
Electrolysis may be used to etch and bring out the structure
of minerals in polished sections. After a drop of the reagent
is placed on the polished surface under the microscope, it was
found that the chemical action could be “speeded up” by the
use of a weak electric current. The current used was furnished
by one dry cell of the same type as used in determining the
comparative electrical conductivity; and the terminals were a
sewing needle and a piece of fine platinum wire; the former being
connected to the carbon pole, and the latter to the zinc pole of
the dry battery. The needle is placed on the polished surface
just outside of the drop of reagent, and the platinum wire brought
into contact with the top of the drop of reagent. Using a 20
per cent. solution of FeCl3 a clot of metallic copper will be
produced on the end of the platinum wire by algodonite, bornite,
chalcocite, native copper, and covelite. With the same reagent
a beautiful “wood grain” structure is developed on enargite,
famatinite, and luzonite, which distinguishes them from tetra-
hedrite and tennantite. The effects of a weak current on the
microchemical reactions may be generalized as follows: (1)
a reagent that is negative when used alone may be strongly
10 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
reactive with the current; (2) any reagent that reacts alone will
give a much more intense reaction with the current; and (3)
if the reagent with the current gives no reaction, it is a good
check that the reagent is truly negative.
The electro-potentials of minerals have been investigated
not only as a possible means of identifying minerals, but also
because of their important bearing upon the processes of en-
richment of ore deposits. Although the results obtained cannot
be considered as of general value for the purpose of identi-
fication, still a summary of the work thus far accomplished
is suggestive and may well lead to further investigation. The
method used in making the test is very simple. A small drop
of dilute nitric acid is applied to the mineral while under the
microscope. The polished section is then removed and a
minute primary cell is established by bringing a standard
electrode into contact with the top of the drop and completing
the circuit, into which has been introduced a millivoltmeter,
with a wire placed on the mineral surface near the drop. Eight
standard electrodes, which are wires composed of a solid solution
of copper and gold and containing, respectively, 100 per cent.,
95 per cent., 90 per cent., 80 per cent., 70 per cent., 60 per cent.,
50 per cent. and 40 per cent. of copper, are used to determine the
direction and intensity of the electric potential difference. The
results of testing many of the minerals having high electrical
conductivity are tabulated in Table 11, page 124, and indicate
the position of the more common ore minerals in the electro-
motive series. These tests have emphasized the fact that when
an active reagent is placed upon the contact of two electrically
conductive minerals, the reagent becomes the electrolyte of a
primary cell in which the minerals in contact are electrodes,
and a weak current will be produced. The result is that
the mineral of lower potential will dissolve more rapidly than
normally, and this demonstrates the fact that microchemical
tests should only be made upon pure material, and that
the influence of impurities may give conflicting microchemical
observations.
The following reagents have been used in this work and
their effects are briefly described in the determinative
tables. They are of the same strength as those used by
Murdoch and thus it has been possible to compare directly the
results obtained.
POLISHING AND EXAMINING THE SPECIMEN
11
HNO3..
HCl.....
KCN.....
FeCl2
HgCl2...
KOH.
One part concentrated acid (sp. gr. 1.42)
and one part water.
One part concentrated acid (sp. gr. = 1.19)
and one part water.
20 per cent. solution in water. 139
20 per cent. solution in water.
N
Saturated solution in water.
Saturated solution in water.
"
s!
N
Care should be taken to use reagents of approximately the
above strength as discordant results are otherwise often ob-
tained. Care should be taken to confine the reagent to the sur-
face of the mineral under examination also because reactions with
soluble gangue substances sometimes confuse the results.
Finally, qualitative chemical tests for the elements can be
applied under the microscope. They are of great value in
certain special problems and the mineragrapher must more
and more resort to them. As a rule two or sometimes three
reagents only are required for such a test and, with very little
practice, results of such nicety can be obtained that, once used,
microchemistry will always hold its place. A condensed list
of the microchemical tests for elements commonly found in the
ore minerals is given in Table 12, page 145.
1 See CHAMOT, E. M. “Elementary Chemical Microscopy.” New
York, 1915.
CHAPTER II
PHOTOMICROGRAPHY OF POLISHED SECTIONS
For the mining geologist, photographs of the ore minerals and
the relations between them, as seen by vertical illumination are
almost indispensable in preparing reports. A well-chosen
illustration will establish a point more conclusively in the minds
of the readers than pages of written description. For the student
of ore deposits, such microphotographs are invaluable records
to be preserved as reference material.
The arrangement is simple, there being a camera in which a
microscope takes the place of the lens. Practically, however,
good results require a high-grade specially designed microscope
and strong artificial light. The procedure has beea borrowed
largely from metallography, except that metallographers seldom
have to bring out color values by optical means, while in miner-
agraphy the variety of different minerals in one section calls
for rather refined methods of color screening or filtering. The
large Leitz metallographic microscope has been used by the
writers, but any good instrument made on the same optical
principles such as the Leitz type manufactured by Bausch and
Lomb would serve equally well. A 5-ampere D.C. arc lamp is
used as the source of light with this microscope. A description
of the construction and specialized directions for the use of such
apparatus are out of place here and are always supplied by the
makers with the instruments. We are, however, concerned
with many factors dealing with the choice of subject and the
technique of photomicrography in general.
First, it is well worth the time to search carefully over all the
polished sections available in order to locate an area which will
best illustrate as many as possible of the important features in
one picture. In too many microphotographs which have
appeared in the literature the reader has to accept on faith the
writer's statement that some relationship is established by the
illustration. It is true that two people may not always interpret
a particular structure in the same way, but it is a rare specimen
which justifies positive conclusions and which does not show
an area illustrating them.
12
PHOTOMICROGRAPHY OF POLISHED SECTIONS
13
When the subject for the photograph has been chosen care
should be taken to adjust the reflector in such a way as to obtain
uniform illumination over the entire field, otherwise a negative
of uneven density will result.
The
proper color screen to bring out the contrasts between the
various minerals must now be selected. The sensitiveness of
the photographic plate to light of different colors or wave lengths
is very different from that of the human eye. Ordinary white
light and light from most artificial sources is a mixture of lights
of all wave lengths. The eye sees all of these colors through a
rather wide range, while the photographic plate "sees" colors
outside of the limits of this range and is “blind" to much that
is within it. For example the eye registers red as a bright color,
but the ordinary plate is unaffected by red light and in a picture
all red objects would appear black. For a complete and inter-
esting treatment of this subject the reader is referred to "The
Photography of Colored Objects" by Dr. C. E. Kenneth Mees.1
Certain dyes have the property of absorbing light of certain
wave lengths and by passing the light to be used through filters
made with these dyes, color effects can be controlled upon the
negative to a large extent. Table 1 lists the Wratten M filters
supplied by the Eastman Kodak Company and indicates the
approximate range of light transmitted by each.
Experience has shown that a filter should be used at all times
as several optical difficulties arise when photography is attempted
without them especially at magnifications greater than 100
diameters. For the average section with a variety of minerals
clearly distinguishable by the eye the Kyellow filter most
nearly reproduces the true values as seen (that is when used
with the Wratten M plate described below). In many cases,
however, when strong contrast is required between two minerals
it is necessary to select one of the special filters described in
Table 1, or, sometimes, one of the combinations of two filters.
This is done usually by trial, the contrast obtained with each
mineral being observed upon the ground glass screen. This
visual trial method is only trustworthy when using a pan-
chromatic plate which approximates the relative sensitiveness
of the eye. The best panchromatic plate obtainable for this
type of work is the Wratten M plate distributed by the East-
1 MEES, C. E. KENNETH. "The Photography of Coloured Objects."
Wratten and Wainwright, Ltd., London, 1913.
14 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
TABLE 11
Visual color
Wratten
filter
Range of spectral transmission in my of
wave length
A...
B...
C...
D...
Scarlet..
Green.
Blue-violet.
Purple....
From 580 to red end
From 460 to 600
From 400 to 510
From 380 to 460 and from 640 to.
red end
From 560 to red end
From 610 to red end
From 510 to red end
From 420 to 540
Wide range of lower spectrum
F..
G...
Blue.....
3
E.... Orange.
Pure red.
Strong yellow
H..
Ki.
Pale yellow (very pale).
K2.
Pale yellow
K;.
Yellow...
D and H... Violet..
Cand H... Blue
B and C... Blue-green.
B and H... Bluish-green
G and H... Pure green.
B and G... | Yellowish-green.
B and E... Greenish-yellow
A and D... Deep red...
+
About 450
About 480
About 500
About 520
About 535
About 550
About 575
About 660
man Kodak Company. It has all the color sensitiveness of the
true panchromatic plate, being even more sensitive to red light,
and has an extremely fine-grained emulsion especially designed
for microscopic photography. The worker along this line
cannot do better than to use it exclusively. All of the data
concerning proper filters and some of the factors for calculating
exposures contained in this chapter are applicable only for use
with the Wratten M plate.
Having chosen the proper filter, accurate focusing is the next
important step. It is impossible to obtain sharp, clear cut
negatives by focusing upon the ground glass screen alone.
After an approximate focus is obtained on this screen it should
be replaced by a plain glass screen upon which the final focus
is made with the use of a lens. This screen should be very
carefully removed and the photographic plate put in its place.
Everything should now be ready for the exposure.
The data for calculating the proper exposure for different
magnifications, sources of light, filters, etc., has been assembled
i From the booklet “Photomicrography" published by the Eastman Kodak Co.
PHOTOMICROGRAPHY OF POLISHED SECTIONS
15
by the Eastman Kodak Company and Tables 2 and 5 have been
taken from their booklets. The formula for calculating expo-
sures gives an approximate figure which should be tested ex-
perimentally for different types of subjects. The formula does
not take this latter factor into consideration, but the same
exposure obviously will not give equally good results on a section
composed largely of white minerals and one in which dark
gray minerals are dominant. The method of making the test
exposure is as follows: If the formula indicates that an exposure
of 20 sec. is about right, expose successive portions of the plate
for 5, 10, 20, 40, and 80 sec. by pulling out the slide and then
pushing it in one-fifth the width of the plate at the end of each
of the above periods. The exposure should increase by geo-
metric progression as indicated rather than by arithmetical
progression such as 10, 15, 20, 25, and 30 sec., as the difference
in density of negatives exposed 10 and 20 sec. respectively is
twice as great as in those exposed 20 and 30 sec. respectively.
With this test plate as a guide, the proper exposure can be easily
determined.
In making the original exposure calculation the following for-
mula is used:
Standard exposure X N.A. factor X source factor X magnifica-
tion factor X filter factor
exposure in seconds.
The standard exposure used in the above empirical equation
is taken as 10 sec.
The exposure varies inversely as the numerical aperture, N.A.
of the objective. (The numerical aperture is an optical constant
for a lens of given focal length.) The factors for the N.A. of
the objectives are given in Table 2.
The source of light naturally is of the greatest importance in
determining the length of exposure. In past publications the
factors for the source of light have been adopted from data for
transmitted light conditions. This has led to confusion because
the polished surface does not reflect all of the light by any means,
and consequently requires a longer exposure. Experience has
shown that, on the average, the factor for reflected light is two
to four times that for direct transmitted illumination. These
factors for various sources of light are given in Table 3.
1 "Photomicrography, Color Plates and Filters for Commercial Photography,
and Reproduction Work with Dry Plates." Eastman Kodak Company,
Rochester, N. Y.
16 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
TABLE 2
Focal length objective
Average N.A.
Approximate ex-
posure factor
Inches
Millimeters
4
3
2
1
23
1/2
13
14
16
78
112
100
75
50
25
16
12
8
6
0.08
0.09
0.15
0.25
0.35
0.45
0.50
0.80
0.85
0.90
1.30
40
30
10
4
2
144
1
24
29
14
74
NA O
.
.
+
.
14
TABLE 3
Exposure factor
Source of light
for M plate
Oil....
3
Incandescent gas.
1
Nernst lamp (1 amp.)
14
Acetylene...
Direct current arc (5 amps.)
18
Direct current arc (10 amps.).
233
Direct current arc (30 amps.)
1330
(It should be understood that the above factors are by nature
very approximate, dependent entirely on arrangement and
power.)
120
110
100
90
80
40mm Obj.
Obji
16 mm. oby
70
Position of Plate (cm.)
5.4 mm.
60
*3 mm. obj.
50
obj:
40
2 mm .
30
20
10
0
500
1500
2000
1000
Magnification
FIG. 3.
PHOTOMICROGRAPHY OF POLISHED SECTIONS
17
The greater the magnification, the longer is the required expo-
sure. The degree of magnifioation depends upon the focal
length of the objective, the projection eyepiece, the distance of
the photographic plate from the objective, etc. It will be found
convenient to prepare a set of curves for the instrument used,
similar to those in Fig. 3, which have been calculated for the
Leitz metallographic microscope.
In Table 4 the exposure factors for different magnifications are
listed.
TABLE 4
Magnification
Exposure factor
for M plate
Magnification
Exposure factor
· for M plate
36
56
10
25
50
100
250
500
K100
116
14
1
6
25
600
750
900
1000
2000
2500
81
100
400
625
The factor for any magnification may be calculated on the basis that
it increases with the square of the diameter.
The last variable in the exposure equation is the factor for the
filter used. These factors are dependent upon the source of
illumination since the different artificial lights have widely differ-
ing color values. Table 5 lists the multiplying factors for the
filters, singly and in pairs, calculated for the open arc and the
Wratten M plate.
TABLE 5
Filter
Factor (M plate and open arc)
Filter
Factor (M
plate and
open arc)
A..
.
1
· B...
C..
D....
E..
F.
G...
H..
K.
10
18
12
Only used in combination
8
15
8
15
114
K2...
K:..
D and G.
A and D.
B and E....
G and H.
B and C.
B and G...
D and H.
3
4%,
250
240
250
1600
600
60
60
.
The foregoing tables are used as follows: the approximate
exposure for a photograph using a 16-mm. objective (Leitz
2
18 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
No. 3), a 5-amp. D.C. arc, magnification 50, and screen K3
would be:
10 sec. X 2 X 18 X 14 X %2 = 3 sec. (approximately)
250
200
150
Magnification
16 mm. Obj.
100
50
40 mm. obj.
0
1 2 3
4
11
12
13
14
15
16
5 6 7 8 9 10
Exposure in Seconds
FIG. 4,
2200
1800
obj.
1400
2 mm.
Magnification
1000
Obj.
60.0
3 to 6 mm.
200
0
10
20 30
40 50 60 70 80 90 100 110 120 130 140 150 160
Exposure in Seconds
Fig. 5.
Figures 4 and 5 give the approximate exposures for an average
specimen consisting, say, of galena, chalcopyrite, and sphalerite.
These curves are calculated solely for the Wratten M plate.
They are for the 5 amp. open arc, wide open stop, and without
PHOTOMICROGRAPHY OF POLISHED SECTIONS
19
filter. When a filter is used the value obtained from the curves
should be multiplied directly by the filter factor taken from
Table 5. These curves are plotted from theoretical values
checked in practice and may be multiplied by a suitable factor
when another light source is used.
The Wratten plate is very sensitive to red light and con-
sequently must be opened and developed either in total dark-
ness or in the light of the Wratten Safelight, series 3, a faint
green light. With each box of plates an instruction sheet is
enclosed giving the developing formula, proper temperatures,
and times of development. These instructions, when followed,
yield excellent results and should only be varied by the most
experienced worker. In the course of the dark room treatment
it will be found advisable to wash the carbon backing off the
plates with a soft sponge while rinsing before placing in the
fixing solution.
In preparing positives a glossy paper usually yields the most
satisfactory detail and reproduces best. After developing and
fixing the print should be pressed face down upon a ferrotype
plate with a rubber roller and allowed to dry thoroughly, when
they will peel off without sticking providing a sufficient amount
of hardening solution has been used in the fixing bath. Small
amounts of a special polishing solution can be used on the ferro-
type plate when necessary and will eliminate sticking entirely.
Such a solution is sold by Burke and James of Chicago, Ill.

CHAPTER III
THE USE OF THE DETERMINATIVE TABLES
The tables have been arranged with the idea of enabling the
student to apply a uniform series of simple and positive tests at
one time to all the different minerals present in appreciable
amounts in the section. The following procedure in making
determinations has been found to yield rapid and exact results.
It must be appreciated that, as in all other things, experience
and practice make for greater skill and, although it has been
demonstrated that beginners can mechanically follow the tables
with fair success, familiarity with the appearance and micro-
chemical behavior of the common ore minerals naturally gives
confidence to the worker. No one should attempt a serious
application of this method of study to any problem without first
applying it to a few of the common minerals.
12
3
FIG. 6.
The polished section of ore pictured in Fig. 6 has been chosen
as an example. This particular ore is of value in this connection
because it illustrates the variety of tests which go toward exact
mineral determinations under the metallographic microscope.
The preliminary examination of the material should be done
20
THE USE OF THE DETERMINATIVE TABLES
21
systematically and the results recorded somewhat as in Table 6.
The different minerals should be temporarily designated by num-
ber and a brief description of their appearance. The reagents
used in the scheme of identification are preferably applied in
their order in the tables and the reactions, if any, observed and
recorded.
TABLE 6
1. Creamy white mineral 2. Yellow 3. Violet white
with high relief
HNO Unaffected for some time, Neg.
Slowly effervesces and
but slowly tarnishes
turns bluish
brown with very slow
effervescence
HCI
Neg.
Neg.
Neg.
KCN Neg.
Neg.
Neg.
Hardness Very high
Medium High to medium
FeCl3 Neg.
Neg.
Neg.
(Pyrite)
(Chalcopyrite) (Polydymite)
In first running down the unknown it is often most convenient
to use the outline of the determinative tables, especially if the
worker is familiar with the more common minerals by sight, be-
cause larger groups of minerals are seen at one time and slight
uncertainties as to the results of one or more tests can be elim-
inated. (1) Readily falls out as pyrite, (2) as chalcopyrite, and
(3) is limited to a small group of minerals. Of these, arsenopy-
rite, willyamite, kallilite, and niccolite all contain arsenic or
antimony. Blowpipe tests applied to a small piece of the mate-
rial gouged from the edge reveal neither of these elements and
polydymite is indicated by a process of elimination.
However, since the mineral was dissolved readily by nitric acid,
a qualitative microchemical test for nickel should be easily applied.
(See Table 12, page 145, for list of these tests.) After a drop of
nitric acid has remained on the supposed polydymite for a minute
or two a drop of tartaric acid is added to keep iron in solution
when a drop of concentrated ammonium hydroxide is next added
to make the solution alkaline. If a drop of a solution of dimethyl
glyoxime in alcohol is now added, a beautiful scarlet-red crystal-
line precipitate appears under the microscope. This proves the
presence of nickel in the unknown and leads to the conclusion
that it is polydymite.
22
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
The foregoing illustrates the general method to be followed in
making identity determinations. All reactions and properties
are utilized when necessary and the individual must be the judge
as to how much evidence is needed in each case before reaching
a decision. This in turn is dependent upon the individual's
experience and familiarity with the properties of the different
minerals as seen under the microscope in reflected light.
ABBREVIATIONS USED IN THE TABLES
+
B.B. = Before the blowpipe.
C. Color seen megascopically.
Fus. = Fusibility.
HNO3 -E = Reacts with HNO3 with effervescence.
HNO3 = Visible reaction such as tarnish, etc. (Without
effervescence in the case of HNO3.)
HNO3 -N = No visible reaction with HNO3. .
H = Hardness high.
L = Hardness low.
M Hardness medium.
Microchem. = Microchemical tests.
O.F. = Oxidizing flame.
R.F. = Reducing flame.
S.Ph. = Salt of Phosphorus.
Str. Streak.
:
THE USE OF THE DETERMINATIVE TABLES
23
OUTLINE OF THE DETERMINATIVE TABLE
Effervesces with HNO3
Color
Mineral
Formula
Page
HCI
KCN
MFeCl3
Cream
Creamy white
Grayish white
Whitneyite
Huntilite
Cuprite
Cu,As
Ag3As
Cu20
33
33
33
L | FeCl3
Creamy white
Creamy white
Purple
Pink
Bluish white
Galena white
Chilenite
Domeykite
Rickardite
(Native copper)?
(Chalcocite)
(HESSITE)
Ag.Bi
CuAs
Cu Tez
Cu
Cuzs
Ag2re
35
35
35
51
51
66
FeCl3-N Creamy white
(Aikinite)
3(CuzPb)S.Bi2S3 63
KCN-N| H | FeCl3_N
White (violet) (Polydymite)
Ni So
57
MFeCl3-N Grayish white
ALABANDITE
Mns
41
L | FeCl3
White
White
Creamy white
Creamy white
Creamy white
Naumannite
Altaite
Native silver
Native bismuth
Tapalpaite
43
43
43
43
(Ag2Pb)Se
PbTe
Ag
Bi
3Ag2(STe).Biz-
(STe):
5PbS.4Sb2S3
PbS
Galena white
Galena white
Plagionite
(Galena)
43
43
77
FeCl3-N Galena white
White
Galena white
Galena white
Grayish white
Grayish white
Galena white
Semseyite
(Aikinite)
(Plagionite)
(Dognacskaite)
(JAMESONITE)
(ALABANDITE)
(Horsfordite)
7PbS.3Sb2S3 45
3(Cu2Pb)S.Bi2S3 63
5PbS.4Sb2S3 43
Cu, Bi, and s 63
2PbS.Sb2S3
62
Mns
41
Cu6Sb
63
HCI-N| KCN
HFeCl3-N | White
(Polydymite)
Ni4S.
57
M] FeCl3
Pink
(Native copper)
Tu
51
L | FeCl3
Pink
Native copper
Bluish white Chalcocite
Pinkish brown (Bornite)
Cu
Cu2S
CusFeS4
51
51
53
FeCl3-N Pinkish brown Bornite
Creamy white (Aikinite)
Galena white (Stibnite)
CuFeSA
53
3(PbCuz)S.Bi2S3 63
Sb2S3
87
KCN-N| H | FeCl3
Creamy pink
Pinkish white
White
Niccolite
Maucherite
Smaltite
NiAs
Ni3AS2
CoAs?
55
55
55
1 Parentheses about a mineral indicate that it is not in its normal position,
24.
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
Effervesces with HNO:
Color
Mineral
Formula
Page
FeCl3-N White
Arsenopyrite
Violet white Polydymite
White
Willyamite
White
Kallilite
Creamy white Pyrite
Creamy white Marcasite
Creamy pink (Niccolite)
FeASS
Ni4S6
(CoNi)Sbs
Ni(SbBi)S
FeS2
FeS2
NiAs
57
57
57
57
57
57
55
MFeCl3
Creamy white
Galena white
Cosalite
Native arsenic
Pb Bi2S.
As
59
59
L | FeCl3
Cream
Creamy white
White
Galena white
Galena white
Creamy white
Creamy white
Galana white
Grayish white
Melonite
CALAVERITE
Native tellurium
Rezbanyite
Tetradymite
(KRENNERITE)
(Native silver)
(Plagionite)
(Petzite)
NizTez
Au Ter-Ag
Te
4PbS.5Bi2S.
Biz(Te, S):
AuTez-Ag
Ag
5PbS.4Sb2S3
(Ag, Au).Te
61
61
61
61
61
63
43
43
97
FeCl3-N Creamy white KRENNERITE
Creamy white Emplectite
Creamy white Chiviatite
Creamy white Aikinite
Galena white Dognacskaite
Galena white Boulangerite
Galena white Horsfordite
(jalena wbite Bismuthinite
Grayish white
REALGAR
Grayish white JAMESONITE
Grayish white Zinkenite
Bluish Gray Tungstenite
White
(Native tellurium)
Galena white (Stibnite)
AuTez-Ag
63
CuBiS2
63
Pb Bi Su
63
3(PbCuz)S.Bi2S3 63
Cu, Bi, and S 63
3PbS.Sb2S3
63
Cu6Sb
63
Bi2S3
62
Ass
62
2PbS.Sb2S3
62
PbS.Sb2S3
62
WS2
62
Te
61
Sb2S3
87
THE USE OF THE DETERMINATIVE TABLES
25
Reacts with HNO3-does not Effervesce
Color
Mineral
Formula
Page
HCI
KCN
M FeCl3-N Creamy white
Galena white
Sulvanite
(Gucjarite)
Cu3VSA
Cu2Sb4S7
65
83
L FeCl3
Creamy white Dyscrasite
Galena white Hessite
Grayish white Argentite
Grayish white Stromeyerite
Grayish white Jalpaite
Brown
(Pyrolusite)
Ag3Sb, Ag8Sb, etc. 67
Ag2Te
66
Ag2S
67
(Ag,Cu)2S
67
3Ag2S.Cu2S 67
MnO2
101
FeCl3-N Bluish white
Brongniardile
PbS.Ag2S.Sb2S3
69
KCN-N| H | FeCl3-N | Gray
PSILOMELANE
H.Mnog
71
MFeCl3
Grayish white
TENORITE
CuO
73
FeCl3-N Gray
Cuprodescloizite
(PbZnCu)4V 200.-
H2O
Zas
Cuo
Gray
Grayish white
(Sphalerite)
(TENORITE)
-
L
FeCl3
Purple
Umangite
White
Clausthalite
Galena white Galena
Galena white Lillianite
Grayish white Teallite
Grayish white Cylindrite
Grayish white Aguilarite
White
(Native antimony)
Creamy white | (Native silver)
Cu3Sez
PbSe
Pbs
3PbS.Bi2S3
PbSns,
Pb Sb2Sn&S21
Ag2S.Ag2Se
Sb
Ag
77
77
77
77
77
77
76
96
43
FeCl3-N
Galena white Meneghinite
Galena white Geocronite
Grayish white Franckeite
White
(Eucairite)
Grayish white (Cylindrite)
4PbS.Sb2S3
5PbS.Sb2S:
Pb.Sn Sb2Siz
Cu Se.Ag2Se
Pb Sb2SnoS21
79
79
79
97
77
HC1-N KCN
MFeCl3
Grayish white (POLYBASITE)
Ag,Sb Se
87
FeCl3-N Pinkish white Luzonite
Brownish white Enargite
Pinkish white FAMATINITE
Galena white Guejarite
Grayish white Freibergite
Yellow
(Chalcopyrite)
Creamy white (Sulvanite)
Grayish white (Tennantite)
Grayish white (Tetrahedrite)
CusAŞS4
Cu3ASS:
CusSbS4
CuzSb4S7
(Cu, Ag)8Sb2S7
CuFeS2
Cu3VSA
CusAs2S7
CusSb2S7
83
83
83
83
82
117
65
117
117
L FeCl3
Grayish white Pearcite
Grayish white (Argentite)
Grayish white (POLYBASITE)
Grayish white (Jalpaite)
Bluish white (Polyargyrite)
AgoA$S6
Ag2S
Ag9SbSe
3A82S,Cu2S
Ag24Sb2S16
85
67
87
67
109
26
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
Reacts with HNO3-does not Effervesce
Color
Mineral
Formula
Page
FeCl3-N Galena white
Galena white
Grayish white
Galena white
Stiboite
KERMESITE
PoLYBASITE
(Livingstonite)
Sb2S3
Sb2S20
AgoSbS.
HgSb.S7
87
87
87
111
KCN-N| H | FeCl3
White
White
White
Chloanthite
Rammelsbergite
GERSDORFFITE
NiAs2
NiA82
NiASS
89
89
89
FeCl-N
White
White
Creamy white
Pinkish white
Cream
Cream
Creamy white
White
White
White
Lollingite
Ullmannite
Linneite
GLAUCODOT
Hauchecornite
(Pyrrhotite)
(Pyrite)
(Chloanthite)
(GERSDORFFITE)
(Willyamite)
FeA82
91
NiSbs
91
COS
91
(Co,Fe) A8S 91
(NiCo)-(SSbBi)91
Fes(S)z
95
FeS2
57
NiA82
89
NiAss
89
(CoNi)Sbs
57
M FeCl3
Pink
Breithauptite
NiSb
93
FeCl3-N Pale yellow
Cream
Cream
Creamy white
Creamy white
Galena white
Grayish white
Grayish white
MILLERITE
Pyrrhotite
Chalmersite
PENTLANDITE
Wittichenite
Andorite
BOURNONITE
Stylotypite
95
95
95
95
95
95
94
Grayish white
Grayish white
Grayish white
Gray
Yellow
Creamy white
Pinkish wbite
Gray
Grayish white
Nis
FeS(S).
CuFe2S3
(Fe, Ni)S
CuzBiS
PbAgSb2S6
(PbCu2)3Sb2S6
3(CuzAg2Fe)-
S.Sb2S3
SnCuFeS4
(CuTiAg)2Se
MnS2
Zns
CuFeS2
CuaVS
CuzSbS
ZnS 0
Cu8A82S7
Stannite
Crookesite
Hauerite
Sphalerite
(Chalcopyrite)
(Sulvanite)
(FAMATINITE)
(Voltzite)
(Tennantite)
94
94
94
94
94
117
65
83
116
117
L
FeCl3
White
White
White
Creamy white
Grayish white
Grayish white
Grayish white
Creamy white
Galena white
Grayish white
Berzelianite
Eucairite
Native antimony
Kalgoorlite
Petzite
Coloradoite
Molybdenite
(Native silver)
(Plagionite)
(Aquilarite)
Cu Se
Cu Se.Ag2Se
Sb
HgAusAg Teo
(Ag,Au) Te
HgTe
MoS2
Ag
5PbS.4Sb2S.
Ag2S.Ag2Se
97
97
96
97
97
97
97
43
43
76
THE USE OF THE DETERMINATIVE TABLES
27
Reacts with HNO3-does not Effervesce
Color
Mineral
Formula
Page
FeCl3-N Pale brown Sternbergite
Galena white Lengenbachite
Galena white Rathite
Galena white Jordanite
Galena white Guitermanite
Galena white Epiboulangerite
Galena white Galenobismutite
Galena white Beegerite
Galena white Freieslebenite
Galena white Nagyagite
Creamy white Sylvanite
Creamy white Guanajuatite
White
(Eucairite)
White
(Berzellanite)
Creamy white (Emplectite)
Galena white (Stibnite)
Galena white (Geocronite)
Galena white (Andorite)
Grayish white (Crookesite)
Grayish white (Regnolite)
Grayish white (JAMESONITE)
AgFe283
99
Pbo(AgCu)zAs4S13 99
Pb(AsSb)S
99
Pb4A82S7
99
3PbS.As2S.
99
Pb3Sb2S:
99
Pb Bi2S4
98
Pb Bi2S,
98
(PbAg2)6Sb4S11 98
Au2PbioSb2TeS16 98
AuAgTez
98
BizSea
98
CuzSe. Ag2Se 97
Cu2Se
97
CuBiS2
63
Sb2S3
87
5PbS.Sb2S3 79
PbAgSb3S6
95
(CuTlAg)2Se 94
CurAs2S12
119
2PbS.Sb2S:
62
28
MICROSCOPIC EXAMINATION OF THE ORE MINERALS
Does not React with HNO3
Color
Mineral
Formula
Page
HCI
KCN
L | FeCl3
Grayish white
Brown
Grayish white
Bluish white
STEPHANITE
Pyrolusite
(Jalpaite)
(Proustite)
Ag.SbS
MnO2
3Ag2S.Cuzs
AgIAsS3
101
101
67
109
KCN-N. MFeCl3-N Grayish white Delafossile
CuO, Fe2O3.
103
HCI-N KCN
M FeCl3
Grayish white
(POLYBASITE)
Ag9SbS6
87
FeCl3-N | Yellow
(Chalcopyrite)
Brownish white (Enargite)
Grayish white (PYRARGYRITE)
CuFeS2
Cu3ASS4
Ag3SbSz'
117
83
111
L | FeCl3
Bluish white Proustite
Bluish white Polyargyrite
Grayish white Cerargyrite
Grayish white (Jalpaite)
Grayish white (Pearcite)
Ag3A$S3
Ag24Sb2S16
AgCi
3A82S.Cuis
AgoAsso
109
109
109
67
85
FeCl3-N Blue
Covellite
Yellow
Native gold
Galena white Livingstonite
Bluish white Onofrite
Grayish white
PYRARGYRITE
Bluish white Miargyrite
Grayish white | Argyrodite
Grayish white ORPIMENT
Bluish white (Proustite)
Grayish white (POLYBASITE)
Cus
Au
HgSb4S7
Hg(SS)
Ag3SbS:
AgSbS2
AgoGeS.
As2S3
Ag3ASS:
Ag9SbS6
111
111
111
111
111
110
110
110
109
87
KCN-N| H | FeCl3
Gray
Uraninite
UO3, etc.
113
FeCl3-N
White
Sperrylite
Pinkish white Cobaltite
Creamy white Hematite
Grayish white Magnetite
Grayish white Ilmenite
Grayish white Rutile
Grayish white Franklinite
PtAs2
CoASS
Fe2O3
Fe3O4
FeTiO3
TiO2
(FeZnMn)O.
(FeMn)203
115
115
115
115
115
115
115
(FeMn)W04
Grayish whitel MANGANESE
OXIDES
Grayish white | WOLFRAMITE
Grayish white Rare earths
Gray
CASBITERITE
Gray (variable) Limonite
Gray
CHROMITE
White
(Lollingite)
SnO2
2Fe2O3.3H20
FeCr204
TeAs2
114
114
114
114
114
114
91
THE USE OF THE DETERMINATIVE TABLES
29
Does not React with HNO3
Color
Mineral
Formula
Page
MFeCl3-N Yellow
Chalcopyrite
Galena white Chalcostibite
Galena white Berthierite
Grayish white Baumhauerite
Grayish white Tetrahedrite
Grayish white Tennantite
Gray
Voltzite
Gray
Erythrozincite
Pale yellow (MILLERITE)
Cream
(Pyrrhotite)
Cream
(Chalmersite)
Creamy white (PENTLANPITE)
Grayish white (BOURNONITE)
CuFeS2
CuSb S2
FeSb2S4
Pb4AsS13
CusSb2S7
Cus As2S71
ZasS40
(MnZn)S
Nis
FeS(S)
CuFeS3
(Fe, Ni)s
(PbCuz)Sb2S
117
117
117
117
117
117
116
116
95
95
95
95
94
L | FeCl3-N Galena white Dufrenoysite
Galena white Matildite
Galena white Lehrbachite
Bluish white Tiemannite
Bluish white Vrbaite
Bluish white Stützite
Grayish white Regnolite
Grayish white Seligmannite
Grayish white Cinnabar
Grayish white Metacinnabarite
Grayish white Patronite
Gray
Lorandite
Galena white (Freieslebentie)
Galena white (Berthierite)
Galena white (Lengenbachite)
Galena white (Rathite)
Grayish white (Baumhauerite)
Grayish white | (Molybdenite)
Gray
(Erythrozincite)
Pb,As2S.
119
AgBiS2
119
PbSe + HgSe 119
HgSe
119
TIAs2SbS
119
Ag4Te
119
Cu7A82S12
119
CuPbAsS3 119
HOS
118
HgS
118
VS4
118
TIASS2
118
(Pb, Ag2).Sb.Sii 98
FeSb2S4
117
Pb6(Ag Cu)2A84813 99
Pb4(AsSb)s 99
Pb4As6S13
117
MOS,
97
(MnZn)s
116
DETERMINATIVE TABLES
See summary of reactions at upper right
hand corner of each page to locate
minerals between thumb tabs.
31
HNOGE
DETERMINATIVE TABLES
HCI
KCN
Med.
FeCl3
CREAM Whitneyite Cu,As (Very Rare)
Microchem. HNO3, Effervesces and turns brown; rubs gray.
Tarnishes and rubs to faint gray showing structure. KCN, Tarnishes
brown; rubs gray with structure. FeCl3, Quickly blackeńs; rubs to
gray. HgCl2, Quickly blackens with structure; rubs light brown with
structure. KOH, Tarnishes faintly.
Hardness, Medium. 3.5. Very Sectile, Gray powder when scratched.
Description. C. and Str.-Silver-white. Usually massive.
B.B. Yields arsenic coat on charcoal (Chap. IV, 2, a) and mirror in
closed tube (IV, 2, c). Gives azure-blue copper chloride flame with
HCI (IV, 6, 6). Fus.—2.
CREAMY WHITE Huntilite? AgzAs? (Very Rare)
Microchem. HNO3, Effervesces and quickly blackens; rubs to roughened
surface. HCI, Liquid scarcely affects surface, but fumes tarnish per-
sistently.
FeCl3, Iarnishes iridescent; rubs to faint iridescence. KOH, Neg.
Hardness, Medium. KCN, Slowly turns dark; rubs to clean roughened
surface.
Description. C.-Dark gray to black. Described from Silver Islet,
Lake Superior, as massive in occurrence.
B.B. Yields arsenic coat on charcoal (IV, 2, a) and mirror in closed
tube (IV, 2, c). When reduced with the fluxes yields metallic silver
(IV, 18, a).
GRAYISH WHITE Cuprite Cu2O
Microchem. HNO3, Effervesces and forms a deposit of metallic copper;
washes to coat of metallic copper; rubs gray. Fumes tarnish. HCI,
Quickly darkens, forming a white coating as seen by inclined light;
rubs faint. Fumes tarnish. KCN, Develops structure; rubs grayish.
FeCl3
, Tarnishes; rubs to iridescence. Fumes tarnish. HgCl2, Neg.
KOH, Neg.
Hardness, Medium. 3.5-4. Slightly brittle, Blood red powder when
scratched. Internal reflection seen by inclined light is deep red.
Description. C.-Red to nearly black. Str.—Shades of red or brown.
With metallic copper it is found in the oxidized zone of all copper de-
posits.
B.B. In R.F. on charcoal yields metallic copper and colors the flame
an emerald-green. Fus.--3.
i The microchemical reactions for minerals marked with an asterisk are
from MURDOCA, JOSEPH, "The Microscopical Determination of the Opaque
Minerals.” John Wiley & Sons. 1916.
33
HNOE
,
DETERMINATIVE TABLES
нСІ
KCN
Low
FeCig
CREAMY WHITE Chilenite* Ag&Bi (Very Rare)
Microchem. HNO3, Effervesces and blackens; rubs to roughened surface.
HCI, Turns brown; rubs to iridescent roughened surface. KCN, Turns
brownish; rubs clean. FeCl3, Tarnishes iridescent; rubs gray. KOH,
Neg.
Hardness, Low.
Description. C.-Silver-white, tarnishing to yellowish. Described as
amorphous and granular.
B.B. When reduced with the fluxes yields metallic silver (IV, 18, a).
With KI & S flux yields brick-red bismuth coat (IV, 3, a).
CREAMY WHITE Domeykite Cugas (Very Rare)
Microchem. HNO3, Quickly effervesces and blackens. HCI, Most
specimens develop structure. KCN, Some portions tarnish faintly,
some practically negative. FeCl, Quickly tarnishes; rubs to rough-
ened surface. HgCl2, Tarnishes brown; rubs faint.' KOH, Quickly
tarnishes; rubs clean.
Hardness, Low to medium. 3-3.5.
Description. C.-Steel gray. Str.-Gray. Occurs reniform, botroidal,
massive, and disseminated.
B.B. Yields arsenic coat on charcoal (IV, 2, a). Gives azure-blue copper
chloride flame with HCl (IV, 6, b).
PURPLE Rickardite Cu Tes (Very Rare)
Microchem. HNO3, Blackens with violent effervescence. HCI, Turns
pale bluish and dissolves to pitted surface. KCN, Bleaches to a pale
tint. FeCl3, Bleaches to brownish. HgCl2, Bleaches to bluish-green.
KOH, Tarnishes iridescent.
Hardness, Low. 3.5. Brittle.
Description. C. and Str.-Purple. Massive; fracture irregular. .
B.B. On charcoal fuses easily to a brittle globule, yielding a pale azure-
blue flame tinged with green, and a white tellurium coat. Fus.1.
PINK
Native Copper
See page 51.
BLUISH WHITE
Chalcocite
See page 51.
GALENA WHITE
HESBITE
See page 66.
35
HNO-E
DETERMINATIVE TABLES
HCI
KCN
Low
FeCl3-N
CREAMY WHITE
Aukinite
See page 63.
37
HNO,-E
DETERMINATIVE TABLES
HCI
KCN-N
High
FeCl-N
VIOLET WHITE
Polydymite
See page 57.
39
HNO-E
DETERMINATIVE TABLES
HCI
KCN-N
Med.
FeCl3-N
GRAYISH WHITE ALABANDITE
Mas
Microchem. HNO3, Effervesces and tarnishes; rubs gray, showing solu-
tion pits. Fumes tarnish brown. HCI, Nearly the same as with #NO3.
KCN, Neg. FeCl3, Neg. HgCl2, Fumes tarnish faintly; washes to pale
brown; rubs clean. KOH, Neg.
Hardness, Medium. 3.5–4. Sectile, but slightly brittle. Olive green
powder when scratched.
Internal reflection seen by inclined light is green.
Description. C.-Iron black. Str.-Green. Has perfect cubic cleavage.
B.B. Shows manganese with the sodium carbonate bead (IV, 11, a).
Fus.--3.
41
HNO, E
DETERMINATIVE TABLES
HCI
KCN-N
Low
FeCl3
-.
WHITE Naumannite* (Ag2Pb) Se (Very Rare)
Microchem. HNO3, Quickly effervesces and blackens; rubs to roughened
surface. HCI, Tarnishes slowly to iridescence. KCN, Neg. FeCla
,
Tarnishes slowly brownish; rubs clean. KOH, Neg.
Hardness, Low. 2.5.
Description. C.-Iron-black. Str.-Black. Massive with cubic cleav-
age.
B.B. Selenium odor and coat on charcoal (IV, 17, a and b). With KI &
S flux yields lemon-yellow lead coat on charcoal (IV, 10, a). Yields
silver button on cupellation (IV, 18, a). Fus.—2.
WHITE Altaite Pb Te (Very Rare)
Microchem. HNO3, Effervesces and quickly darkens, developing crys-
tals and tree-like forms resembling microlites; rubs to grayish etched
surface. Fumes tarnish iridescent. HCI, Quickly browns; rubs to
pale brown with white patches. KCN, Neg. FeCls, Quickly tar-
nishes brownish iridescent; rubs to gray, roughened surface. Ég Cl2,
Neg. KOH, Neg.
Hardness, Low. 3. Sectile. Gray powder when scratched.
Description. C.-Tin-white. Str.-Gray. Has cubic cleavage.
B.B. Yields tellurium flame and coat on charcoal (IV, 20, a). With
KI & S flux gives a lemon-yellow lead coat on charcoal. Fus.-1.5.
CREAMY WHITE Native Silver Ag
Microchem. HNO3, Effervesces slightly for a moment; rubs to gray,
roughened surface. Fumes tarnish. HCI, Fumes tarnish slightly;
rubs clean. KCN, Neg. FeCl3, Tarnishes iridescent; rubs to irides-
cence. HgCl2, Tarnishes gray; rubs to brownish gray. KOH, Neg.
Hardness, Low. 2.5-3. Very sectile.
Description. C.-Silver-white. Str.—Silver-white. Usually in arbor-
escent, sheet, and wire forms.
B.B. Fuses easily on charcoal and yields a brown coat of silver oxide.
(For other tests see IV, 18, a.) Fus.—2.
CREAMY WHITE Native Bismuth Bi (Very Rare)
Microchem. HNO3, Quickly effervesces and darkens; rubs to brownish
gray. HCI, Slowly darkens; Fumes tarnish brown. KCN, Neg.
Fečls, Darkens quickly. HgCl., Slowly deep brown; rubs to brown.
KOH, Neg.
Hardness, Low. 2-2.5. Very Sectile.
Description. C.-Reddish silver-white. Str.-Silver-white. Arbores-
cent.
B.B. On charcoal fuses easily and volatilizes completely, yielding yellow
sublimate. With KI & S Äux gives brick-red coat on charcoal.
CREAMY WHITE Tapalpaite 3Ag2(STe). Biz(STe);? (Very Rare)
Microchem. HNO3, Quickly effervesces and darkens; rubs to dark, rough
surface. Fumes tarnish. HCI, Faintly tarnished; rubs clean. Fumes
same. KCN, Neg. FeCl3, Quickly darkens; rubs to gray, roughened
surface. KOH, Neg.
Hardness, Low.
Description. C.-Pale steel-gray. Str.-Gray. Massive.
B.B. Yields tellurium flame and coat on charcoal (IV, 20, a). With
KI & Sflux gives brick-red bismuth coat on charcoal (IV, 3, a). Fus.-1.
GALENA WHITE Plagionite 5Pb S.4Sbs (Very Rare)
Microchem. HNO3, Slowly darkens with slight effervescence; rubs to
light gray. HCI, Acid negative, but fumes tarnish bright brown.
KCN, Neg. FeCl3, Turns brown; rubs pale brown. HgCl2, Neg.
KOH, Slowly iridescent; rubs clean.
Hardness, Low. 2.5. Brittle. Gray powder when scratched.
Description. C. --Blackish gray. Str.-Black.
B.B. Yields antimony coat and sublimates (IV, 1, a-d). With KI & S
flux gives lemon-yellow lead coat (IV, 10, à). Fus.—1.
GALENA WHITE Galena See page 77.
43
.
*
HNO3-E
DETERMINATIVE TABLES
HCI
KCN_N
Low
FeCl3-N
GALENA WHITE Semseyite 7PbS.3Sb2S3 (Very Rare)
Microchem. HNO3, Slowly effervesces and blackens; rubs gray. Fumes
tarnish brown. HCI, Slowly faint brown; rubs clean. Fumes tarnish.
KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOH, Some specimens unaf-
fected; others faintly tarnish brown.
Hardness, Low. Brittle. Gray powder when scratched.
Description. C.-Gray. Str.Black. Tabular.
B.B. Yields antimony coat and sublimates (IV, 1, a-d). With KI & S
flux gives lemon-yellow coat (IV, 10, a). Fus.-1.
WHITE
Aikinite
See page 63.
GALENA WHITE
Plagionite
See page 43.
GALENA WHITE
Dognacskaite See page 63.
GRAYISE WHITE
JAMESONITE
See page 62
GRAYISH WHITE
ALABANDITE See page 41.
GALENA WHITE
Horsfordite
See page 63.
45
HNO3-E
DETERMINATIVE TABLES
HCI-N
KCN
High
FeCl-N
VIOLET WHITE
Polydymite
See page 57.
47
HNO-
DETERMINATIVE TABLES
HCl-N
KCN
Med.
FeCl2
PINK
Native Copper
See page 51.
49
HNO3-E
.
DETERMINATIVE TABLES
HCI-N
KCN
Low
FeCl3
PINK Native Copper Cu
Microchem. HNO3, Effervesces without tarnishing; rubs to roughened
surface. HCI, Neg. (Sometimes tarnishes faintly.). KCN, Slowly
browns; rubs to clean roughened surface. FeCl3, Quickly darkens
and dissolves. HgCl2, Quickly blackens; rubs to iridescence. KOH,
Slowly turns brown to bluish; rubs bluish.
Hardness, Medium. 2.5–3. Sectile. Pink when scratched.
Description. C.-Copper-red. Str.-Shining. Malleable, ductile. Shows
arborescent and irregular structures. Occurs in oxidized zone of all
copper deposits.
B.B. Easily fusible, yielding an emerald-green flame in the O.F. On
charcoal becomes black after fusion.
BLUISH WHITE Chalcocite Cu2S
Microchem. HNO3, Effervesces vigorously, turning blue, and developing
cracks or cleavage; rubs same. HCI, Tarnishes very slightly. KCN,
Quickly blackens; rubs to etched surface, with structure. FeCl3,
Tarnishes slightly. HgCl2, Tarnishes slightly. KOH, Neg.
Hardness, Low. 2.5-3. Very Sectile. Gray powder when scratched.
Description. C. and Str.—Dark lead-gray, tarnishing to blue on ex-
posure.
Occurs in zone of secondary enrichment in all copper de-
posits.
BB. Fuses easily and boils with spirting. Powdered and roasted with-
out fusing, then heated in R.F., yields metallic copper. Fus.—2–2.5.
PINKISH BROWN
Bornite
See page 53.
51
HNOZE
DETERMINATIVE TABLES
HC1-N
KCN
Low
FeCl3-N
PINKISH BROWN Bornite CusFeS4
Microchem. HNO3, Effervesces and turns yellowish brown; rubs to
brown etched surface. Fumes tarnish. HCI, Neg. KCN, Browns;
rubs to dark etehett surface. Fumes tarnish. FeCl3, Neg. HgCl2,
Neg. KOH, Neg.
Hardness, Low. 3. Sectile. Golden-brown powder when scratched.
Description. C.-Copper-red to brown; purplish bronze from tarnish.
Str.-Grayish black. Massive. Common in most copper deposits.
B.B. Fuses easily on coal in the R.F. to a magnetic globule. Roasted
and reduced with sodium carbonate, yields malleable copper buttons
(IV, 6, a). Fus.-2.
CREAMY WHITE
Aikinite
See page 63.
GALENA WHITE
Stibnite
See page 87.
53
HNO3-E
DETERMINATIVE TABLES
HCI-N
KCN-N
High
FeC13
| NiAs
7
CREAMY PINK Niccolite
Microchem. HNO3, Effervesces and tarnishes with etching; rubs to
gray, etched surface. Fumes tarnish. HCI, Neg. KCN, Neg. FeCl3,
Slowly tarnishes brown; rubs to pale brown. (Some specimens show
this reaction very weakly.) HgCl2, Tarnishes brown; washes to per-
sistent brown. KOH, Neg.
Hardness, High. 5-5.5. Very brittle. Gray powder when scratched.
Description. C.-Pale copper-red. Str.—Brownish. Occurs massive
and disseminated.
B.B. Fuses easily on coal to brittle globule, yielding arsenical odor and
possibly a white coat of oxide. With dimethyl glyoxime gives a red
precipitate (IV, 14, 6).
ܕ2
PINKISH WHITE Maucherite NizAsz (Very Rare)
Microchem. HNO3, Effervesces and blackens quickly; rubs to gray,
rough surface. HCl, Neg. KCN, Neg. FeCl3, Slowly tarnishes
brownish; rubs faint. HgCl2, Faintly browns; rubs clean. KOH,
Neg.
Hardness, High. 5. Very brittle. Gray powder when scratched.
Description. C.—Reddish silver-white, tarnishing gray copper-red.
Str. --Blackish gray.
B.B. Same as niccolite.
(NOTE: Temiskamite is not a mixture, but a homogeneous mineral
identical with Maucherite.)
WHITE Smaltite CoAs2
Microchem. HNO3, Quickly effervesces and darkens; rubs to gray, show-
ing lath structure. Fumes tarnish. HCI, Neg. KCN, Neg. FeCl3
,
Slowly tarnishes brownish, showing structure; rubs pale. (This reaction
is not always decisive.) ' HgCl2, Slowly browns; rubs clean. KOH,
Neg.
Hardness, High. 5.5-6. Brittle.
Description. C.-Tin-white. Str.-Gray-black. Occurs massive.
B.B. Easily fusible on charcoal, yielding a magnetic globule and an
arsenical odor; may yield a white arsenic coat. With borax shows a
persistent cobalt blue (IV, 5, a). Fus.—2.5.
(Safflorite is the same as smaltite.)
55
HNOz-E
DETERMINATIVE TABLES
HCI-N
KCNN
High
FeCl3-N
WHITE Arsenopyrite FeAss
Microchem. HNO3, Slowly effervesces and quickly tarnishes through
iridescence to_deep brown;
rubs to roughened surface. HCI, Neg.
KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, High. 5.5-6. Brittle. Gray powder when scratched.
Description. C.-Silver-white to steel-gray. Str.-Grayish black. Oc-
curs as orthorhombic crystals, massive, granular, or compact.
* B.B. On charcoal fuses easily to brittle magnetic globule and evolves
arsenic odor. In the closed tube it yields first an arsenious sulphide
sublimate and then an arsenic mirror. Fus.-2.
VIOLET WHITE Polydymite Ni_S. (Very Rare)
Microchem. HNO3, Slowly effervesces and turns to brownish or bluish;
rubs to brown or blue, showing structure. HCI, Neg. ,(Acid turns
green, but surface washes clean.) KCN, Neg. FeCl3, Neg. HgCl2,
Neg. KOH, Neg.
Hardness, High. 4.5. Brittle.
Description. C.-Steel-gray. Str.-Grayish black.
B.B. With dimethyl glyoxime yields red precipitate (IV, 14, b). Fus.-
2.
WHITE Willyamite* (CoNi)Sbs (Very Rare)
Microchem. HNO3, Slowly effervesces and turns dark brown; rubs gray,
showing etching. HCI, Neg. KCN, Neg. FeCl3, Neg. KOH, Neg.
Hardness, High. °5.5.
Description. C.--Tin-white to steel-gray. Str.-—Grayish black. Per-
fect cubic cleavage. Massive.
B.B. Tests for cobalt, nickel, and antimony in Chapter IV.
WHITE
Kallilite* Ni(Sb Bi)S?
(Very Rare)
Microchem. Like Willyamite.
Hardness, High to medium.
Description. C.-Light bluish gray. Str.Black. Massive.
B.B. Tests for nickel, antimony, and bismuth in Chapter IV.
CREAMY WHITE Pyrite Fes?
Microchem. HNO3, Very slowly effervesces and faintly browns; rubs
to faint brown. Fumes tarnish slowly. Other reagents negative.
Hardness, High. 6-6.5. Cannot be scratched.
Description. C.-Light brass-yellow. Str.-Greenish to brownish black.
Pyrite is the most common of all sulphides and usually the oldest.
B.B. Becomes magnetic on charcoal in the R.F. Fus.-3.
FeS2
CREAMY WHITE Marcasite
Microchem. Like Pyrite.
Hardness, High. 6-6.5.
Description. Like Pyrite except in crystal form and in occurrence.
occurs always as a secondary mineral,
B.B. Like Pyrite.
It
CREAMY PINK
Niccolite
See page 55.
57
HNO-E
DETERMINATIVE TABLES
HCI-N
KCN-N
Med.
FeCl3
CREAMY WHITE Cosalite Pb2Bi2S6 (Very Rare)
Microchem. HNO3, Instantly effervesces and blackens; rubs to dark
gray. Fumes tarnish. HCl, Neg. (Sometimes slowly faint tarnish;
rubs clean.) KCN, Neg. FeCl3, Very slowly faint brown; sometimes
appears negative. HgCl2, Fumés tarnish; rubs clean. KOH, Tar-
nishes brown to iridescent.
Hardness, Medium to low. 2.5-3. Brittle. Gray powder when scratched.
Description. C.-Lead-gray. Str.-Grayish black.
B.B. With KI & S flux shows both lead and bismuth (IV, 3 and 10).
Fus.-1.5.
GALENA WHITE Native Arsenic As (Very Rare)
Microchem. HNO3, Instantly blackens with slow effervescence; rubs to
brownish gray. HCI, Neg. KCN, Neg. FeCls, Quickly darkens
to persistent brownish. HgCl2, Slowly tarnishes pale brown; rubs
faint. KOH, Neg.
Hardness, Medium to low. 3.5. Sectile, but slightly brittle. Gray
powder when scratched.
Description. C.-Tin-white. Str.--Gray. Has a basal cleavage.
B.B. Yields white arsenic oxide coat on coal and easily volatilizes without
fusion.
59
HNO3-E
HC1-N
DETERMINATIVE TABLES
KCN-N
Low
FeCl3
CREAM Melonite*
Ni Tez
(Very Rare)
Microchem. HNO3, Quickly effervesces and blackens; rubs gray. HCI,
Neg. KCN, Neg. FeCl3, Slowly tarnishes; rubs faint. KOH, Neg.
Hardness, Low.
Description. C.-Reddish white. Str.--Gray. Has basal cleavage.
B.B. Easily fusible, but not entirely volatile, yielding white coat on
charcoal and coloring flame bright green (IV, 20, a). With dimethyl
glyoxime gives a red precipitate (IV, 14, b).
CREAMY WHITE CALAVERITE Au Teg + Ag
Microchem. HNO3, Slowly effervesces and turns brown; rubs to lighter
brown with etching. HCI, Neg. KCN, Neg. FeCl3, Slowly tarnishes
brown; rubs to faint brown. HgCl2, Neg. KOH, Tarnishes pale
brown; rubs to faint brown.
Hardness, Low. 2.5. Brittle. Gray powder when scratched.
Description. C.-Silver-white. Str.–Gray.
B.B. Gives white coat on charcoal and colors flame bright green.
Roasted and reduced with sodium carbonate, yields gold and silver;
sometimes reduces to gold bead easily without soda. Fus.-1.
WHITE Narive Tellurium Te (Very Rare)
Microchem. HNO3, Quickly effervesces and blackens; rubs to gray,
rough surface. HCl, Neg. KCN, Neg. FeCl3, Slowly tarnishes
iridescent. KOH, Neg.
Hardness, Low. 2-2.5. Somewhat sectile. Gray powder when
scratched.
Description. C.-Tin-white. Str.-Gray. Has prismatic cleavage.
B.B. Easily fusible and volatile, yielding a white coat on charcoal and
coloring the flame bright green (IV, 20, a). Fus.-1.
GALENA WAITE Rezbanyite 4PbS.5Bi2S3 (Very Rare)
Microchem. HNO3, Effervesces and tarnishes iridescent; rubs to gray
etched surface. Fumes tarnish. HCl, Neg. KCN, Neg. FeCl3,
Slowly faint brown. HgCl2, Neg. KOH, Neg.
Hardness, Low. 2.5-3. Brittle. Gray powder when scratched.
Description. C.-Lead-gray. Str.-Grayish black. Massive.
B.B. With KI & S flux shows both lead and bismuth (IV, 3 and 10).
May be isomorphous with small amounts of copper and silver.
GALENA WHITE Tetradymite Big(Te,S);
Microchem. HNO3, Quickly tarnishes with vigorous effervescence; rubs
iridescent. HCI, Neg. KCN, Neg. FeCl3
, Tarnishes slightly,
developing scratches. HgCl2
, Neg. KOH, Neg.
Hardness, Low. 1.5-2. Slightly sectile.
Description. C.-Steel-gray, splendent. Str.-Gray. Perfect basal
cleavage. Soils paper.
B.B. On charcoal fuses, gives white fumes and entirely volatilizes; tinges
the R. F. bluish-green; coats the charcoal at first white and finally
orange yellow
CREAMY WHITE KRENNERITE See page 63.
CREAMY WHITE
Native Silver
See page 43.
GALENA WHITE
Plagionite
See page 43.
GRAYISH WHITE
Petzite
See page 97.
61
GALENA WHITE Bismuthinite Bi2S3 (Very Rare)
Microchem. HNO3, Blackens with slow effervescence; rubs to gray,
roughened surface. HCI, Neg. KCN, Nég. FeCl3, Neg.: HgCia,
Tarnishes brown; rubs to faint brown. KOH, Neg.
Hardness, Low. 2. Slightly brittle. Gray powder when scratched.
Description. C.-Lead-gray.
B.B. With KI & S flux gives a brick-red bismuth coat on charcoal
(IV, 3, a). Fus.—1.
GRAYISH WHITE REALGAR
ASS
Microchem. HNO3, Effervesces without visible change. HCI, Neg.
KCN, Neg. FeCl3
, Neg. HgCl2, Neg. KOH, Tarnishes brown to
black with solution.
Hardness, Low. 1.5-2.
Internal reflection seen by inclined light is orange.
Description. C.-Dark orange-red. Str.-Lighter. Occurs with anti-
mony, arsenic, and silver ores.
B.B. On charcoal in the O.F., burns, yielding arsenic odor and no
residue when pure. In closed tube yields cherry-red sublimate of
arsenic sulphide. Fus.-1.
GRAYISH WHITE
JAMESONITE 2PbS.Sb2S3
Microchem. HNO3, Quickly brown to black with very slow effervescence
(Eff. often not detected); rubs to iridescent gray. HCI, Neg. Fumes
tarnish slowly; rubs faint. KCN, Neg. FeCl3, Neg. HgCl2, Neg.
KOH, Slowly develops grain structure; some grains are iridescent,
others gray.
Hardness, Low. 2-3. Brittle.
2-3. Brittle. Gray powder when scratched.
Description. C.-Steel-gray. Str.—Grayish black. Perfect basal cleav-
age.
Occurs fibrous or massive.
B.B. Yields antimony and lead coat on charcoal (IV, 1 and 10). With
KI & S flux gives lemon-yellow lead coat on charcoal (IV, 10, a).
Fus.-1.
GRAYISH WHITE Zinkenite PbS.Sb2S3 (Very Rare)
Microchem. Like Jamesonite.
Hardness, Low. 3–3.5.
Description. C. and Str.-Steel-gray. Occurs in columnar crystals,
striated lengthwise, also fibrous and massive.
B.B. Like Jamesonite.
BLUISH GRAY Tungstenite WS,(?) (Very Rare)
Microchem. HNO3, Does not change color, but effervesces after a few
moments. HCI, Neg.
HCI, Neg. KCN, Neg. FeCl3, Neg. HgCl2, Quickly tar-
nishes brown; rubs clean. KOH, Neg.
Hardness, Low. 2.5.
Description. C.-Dark lead-gray. Str.—Dark gray. Marks paper.
B.B. See tests for tungsten (IV, 25).
WHITE
Native Tellurium
See page 61.
GALENA WHITE
Stibnite
See page 87.
62
HNO3-E
HCl-N
DETERMINATIVE TABLES
KCNẠN
Low
FeCl3-N
CREAMY WHITE KRENNERITE Au Tez + Ag
Microchem. HNO3, Slowly effervesces and turns brown; rubs to lighter
brown with etching. HCI, Neg. KCN, Neg. FeCl3, Neg. HgCl2,
Neg. KOH, Tarnishes pale brown; rubs to faint brown.
Hardness, Low to medium. 2.5. Sectile, but slightly brittle. Gray
powder when scratched.
Description. C.-Silver-white. Str.-Gray. Has perfect basal cleav-
age. (Calaverite lacks this perfect cleavage.)
B.B. Gives white coat on coal and colors flame bright green. Roasted
and reduced with sodium carbonate yields gold and silver; sometimes
reduces to gold bead easily without soda. Fus.-1.
CREAMY WHITE Emplectite CuBiS2 (Very Rare)
Microchem. HNO3, Effervesces slightly and tarnishes pale brown; rubs
clean. Fumes tarnish faintly. HČI, Neg. KCN, Neg. FeCla,
Neg. HgCl2, Neg. KOH, Tarnishes very slowly brown; rubs clean.
Hardness, Low. 2. Slightly brittle. Gray powder when scratched.
Description. C.-Grayish white. Str.—Black.
B.B. Yields azure-blue copper chloride flame with HCl (IV, 6,5). With
KI & S flux gives brick-red bismuth coat on charcoal (IV, 3, a). Fus.-1.
CREAMY WHITE Chiviatite* Pb2Bi2S11 (Very Rare)
Microchem. HNO3, Slowly effervesces and turns iridescent to gray; rubs
to clean, somewhat roughened surface. HCI, Neg. KÖN, Neg.
FeCl3, Neg. KOH, Neg.
Hardness, Low.
Description. C.-Lead-gray. Str.—Grayish black. Commonly foli-
B.B. With KI & S flux shows both lead and bismuth (IV, 3 and 10).
CREAMY WHITE Aikinite 3(PbCuz)S.Bi2S3 (Very Rare)
Microchem. HNO3, Effervesces and blackens; rubs to heavy gray.
Fumes tarnish brown. HCI, Neg. KCN, Neg. (Some specimens very
slowly browned; rubs clean.) FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Low. 2-2.5. Brittle. Gray powder when scratched.
Description. C.-Lead-gray. Str.-Grayish black.
B.B. Gives azure-blue copper chloride flame with HCI (IV, 6,5). With
KI & S flux shows both lead and bismuth (IV, 3 and 10). Fus.-
1-1.5.
GALENA WHITE Dognacskaite Cu, Bi, and S (Very Rare)
Microchem. HNO3, Quickly effervesces and turns iridescent to black;
rubs to gray, roughened surface. Fumes tarnish. HCI, Neg. Fumes
tarnish brown; rubs to pale brown. KCN, Neg. FeCl3, Neg.
HgCl2, Neg. KOH, Neg.
Hardness, Low. Very Sectile. Gray powder when scratched.
Description. C.-Gray, tarnishing on exposure to the air.
B.B. Same as Emplectite.
GALENA WHITE Boulangerite 3PbS.Sb2S3 (Very Rare)
Microchem. HNO3, Effervesces and blackens; washes to etched struc-
ture. Fumes tarnish light brown. Other reagents negative.
Hardness, Low. 2.5-3. Sectile, but slightly brittle. Gray powder when
scratched.
Description. C.-Bluish lead-gray. Str.—Black. Occurs fibrous, granu-
lar, or compact.
B.B. Like Jamesonite.
GALENA WHITE Horsfordite Cu.Sb (Very Rare)
Microchem. HNO3, Slightly effervesces and quickly blackens; rubs to
faint gray. HCI, Practically negative; some specimens turn very
slowly faint brown and rub to very faint gray. KCN, Neg. FeCl3,
Neg. HgCl2, Tarnishes a brown rim which rubs clean. KOH, Slowly
tarnished faintly.
Hardness, Low. Very Sectile. Gray powder when scratched.
Description. C.-Silver-white. Occurs massive.
B.B. Reacts for antimony and copper. Fus.–1.5.
63
HNO:
DETERMINATIVE TABLES
NATI
HCI
KCN
Med.
FeCl3-N
CREAMY WHITE Sulvanite Cu:VS4 (Very Rare)
Microchem. HNO3, Neg. Fumes tarnish; rubs clean. HCI, Neg.
Fumes tarnish; rubs clean. KCN, Neg. Fumes tarnish; rubs clean.
FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Medium. 3.5. Brittle. Gray powder when scratched
Description. C.-Bronze-yellow. Occurs massive. (South Australia.)
B.B. Roasted and reduced with sodium carbonate and borax yields cop-
per buttons. Gives vanadium bead with the fluxes (IV, 27, a).
GALENA WHITE
Guejarite
See page 83.
65
GALENA WHITE Hessite Ag Te
Microchem. HNO3, Slowly tarnishes iridescent to brown; rubs to rough-
ened surface. (Sometimes slowly effervesces.) HCI, Tarnishes irides-
cent; rubs faint or clean. (Sometimes nearly negative.) KCN,
Slowly tarnishes. FeCl3, Tarnishes iridescent;
rubs faint to clean.
HgCl2, Tarnishes brown; rubs clean. KOH, Very slowly tarnishes
slightly; rubs faint.
Hardness, Low. 2.5–3. Quite sectile.
Description. C.-Steel-gray. Str.-Gray. Occurs crystalline, massive,
etc.
B.B. Coat and flame are not decisive. Shows tellurium with concen-
trated H2SO4. Reduced with sodium carbonate, yields silver buttons.
Fus.-1.
BROWN
Pyrolusite
See page 101.
66
HNO,
DETERMINATIVE TABLES
HCI
KCN
Low
FeCl3
CREAMY WHITE Dyscrasite Ag3Sb, Ag Sb, etc. (Very Rare)
Microchem. HNO3, Tarnishes and develops differential etching. HCI,
Slowly tarnishes with development of differential etching. KCN,
Slowly and faintly etches differentially. FeCl3, Differential iridescent
tarnish. · HgCl2, Tarnishes to brownish iridescence with structure;
rubs same. Fumes tarnish light brown. KOH, Neg.
Hardness, Low. 3.5-4. Exceedingly sectile.
Description. C.-Silver-white, sometimes tarnishing yellow or blackish.
Str. -Silver-gray.
B.B. Easily fuses to a globule, coating the charcoal with white antimony
trioxide, and finally leaving a globule of pure silver. Soluble in nitric
acid. Fus.—1.5.
GRAYISH WHITE Argentite Ag2S
Microchem. HNO3, Slowly tarnishes light brown; rubs clean. Fumes
tarnish brown. HCI, Sometimes slowly tarnishes faint brown, but
often almost negative. KCN, Tarnishes brown; rubs to faint gray.
Fumes tarnish brown. FeCl3, Slowly brown to iridescent; rubs to very
faint iridescence. HgCl2, Tarnishes brown; rubs to pale brown.
KOH, Neg. Blackened by short exposure to unscreened strong elec-
tric arc light.
Hardness, Low. 2–2.5. Exceedingly sectile. Black powder when
scratched.
Description. C.-Lead-gray. Str.--Shining gray. Common in many
silver deposits and also occurs in disseminated small crystals in silver
bearing lead minerals, etc.
B.B. Fuses with intumescence in the O.F. on charcoal, emitting sulphur
dioxide odor and a globule of pure silver. Fus.—1.5.
GRAYISH WHITE Stromeyerite
(Ag, Cu), (Very Rare)
Microchem. HNO3, Tarnishes slightly with etching; rubs to rough gray.
Fumes tarnish. HCI, Slowly very faint brown.
(Sometimes prac-
tically negative.) Fumes tarnish. KCN, Tarnishes brown; rubs to
FeCl3, Quickly tarnishes brown or iridescent with struc-
ture; rubs to brownish iridescence. HgCl2, Tarnishes brown; rubs to
pale yellowish. KOH, Neg.
Hardness, Low. 2.5–3.
2.5-3. Very sectile. Black powder when scratched.
Description. C. and Str.—Dark steel-gray. "Prismatic, massive, com-
pact.
B.B. Fuses in the 0. F. on charcoal to a semi-malleable globule, which
reacts for copper (IV, 6)
and cupelled with lead yields a silver button.
Soluble in nitric acid. Fus.-1.5.
faint gray.
GRAYISH WHITE Jalpaite 3 Ag2S.Cu2S? (Very Rare)
Microchem. HNO3, Acid has no effect, but the fumes tarnish slowly
brown; rubs clean. HCI, Acid turns green and surface is slightly
roughened, but the reaction often appears negative. KCN, Tarnishes
brown very slowly; rubs clean. FeCl3, Tarnishes and rubs to faint
greenish iridescence. HgCl2, Tarnishes brown; rubs to faint spot.
Fumes tarnish. KOH, Neg.
Hardness, Low. Specimen from Tres Puntas, Chili is brittle and has a
blood red powder when scratched. Internal reflection seen with in-
clined light is blood red.
Description. C.-Blackish lead-gray.
B.B. Like stromeyerite.
67
HNO2
DETERMINATIVE TABLES
HCI
KCN
Low
FeCl2-N
BLUISH WHITE Brongniardite* PbS.Ag2S.Sb2S3? (Very Rare)
Microchem. HNO3, Slowly tarnishes pale brown; rubs clean. HCI,
Slowly tarnishes faint brown; rubs clean. KCN, Slowly tarnishes faint
brown; rubs clean. FeCl3, Neg. KOH, Tarnishes iridescent; rubs to
clean etched surface.
Hardness, Low. 3+.
Description. C. and Str.-Grayish black. Massive.
B.B. On charcoal, decrepitates, fuses easily, and gives off sulphur dioxide
vapors. Upon roasting yields an impure globule of silver and a yellow
coating of lead oxide. In the closed tube yields a faint orange sub-
limate. In the open tube, fuses, and yields a sublimate of white anti-
mony trioxide. Fus.-1.
69
HNO3
DETERMINATIVE TABLES
нсі
KCN_N
High
FeCl3-N
GRAY PSILOMELANE HM906?
Microchem. HNO3, Acid tarnishes faintly; fumes strongly. Rubs
nearly clean. HĆI, Tarnishes and rubs faint brown. KČN, Neg.
FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, High. 5-6. Brittle.
Description. C.--Iron-black. Str.-Shining brownish black. Massive,
botroidal, reniform, and stalactitic.
B.B. Infusible. In the closed tube yields water. Yields a green bead
with sodium carbonate (IV, 11, a). Soluble in HCl with evolution of
chlorine. May contain enough iron to become magnetic when roasted.
71
HNO
DETERMINATIVE TABLES
нСІ
KCN-N
Med.
FeCl2
faint gray.
GRAYISH WHITE Tenorite Cuo (Very Rare)
Microchem. HNO3, Acid without effect, but fumes tarnish; washes clean.
HCI, Tarnishes and deposits a mass of white acicular crystals; rubs to
Fumes tarnish. KCN, Neg. FeCl3, Tarnishes pale
brown very slowly; rubs clean. HgCl2, Neg. KOH, Neg.
Hardness, Medium. 344. Slightly brittle.
Description. C.-Iron-gray to black. Str.-Black. Occurs massive,
crusted, in minute crystals, and scales. Found in oxidation zone in
some Cu deposits.
B.B. Like cuprite (page 33).
73
HNO,
DETERMINATIVE TABLES
HCI
KCN-N
Med.
FeC12-N
GRAY Cuprodescloizite (Pb, Zn, Cu).V,0,.H,O? (Very Rare)
Microchem. HNO3, Blackens; rubs to roughened surface. Fumes
tarnish brown. HCI, Tarnishes with structure, acid turning yellow;
rubs to slightly roughened surface. Fumes tarnish. KČN, Neg.
FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Medium. 3.5. Brittle. Reddish yellow powder when
scratched. Internal reflection as seen by inclined light is greenish or
yellowish brown, but may not always be noticeable.
Description. C.—Dull green to greenish black or yellowish brown.
Usually in crusts or reniform masses with mammillary surface and
columnar structure.
B.B. In the closed tube yields water. Will test for constituents in the
formula above as well as for arsenic and other impurities. (See Chap.
IV.)
GRAYISH WHITE
TENORITE
See page 73.
GRAY
Sphalerite
See page 94.
75
GRAYISH WHITE Aguilarite Ag2S.Ag Se (Very Rare)
Microchem. HNO3, Slowly tarnishes brown; rubs clean. Fumes tarnish.
HCI, Acid without effect, but fumes often tarnish brown; rubs to faint
brown. KCN, Neg. FeCl3, Slowly tarnishes iridescent; rubs to faint
iridescence. HgCl2
, Tarnishes brown to iridescent; rubs to iridescence.
KOH, Neg.
Hardness, Low. 2.5. Extremely sectile.
Description. C.-Iron-black. Štr.-Black.
B.B. On charcoal yields a white coat with metallic-like luster, also a
selenium odor and blue flame. Heated slowly in the open tube yields
metallic silver. Fus.--1.
76
ANO,
drical forms separating into distinct shell?
нс1
DETERMINATIVE TABLES
KCN-N
Low
FeCl2
PURPLE Umangite*
CuzSez
(Very Rare)
Microchem. HNO3, Turns blue; rubs same. HCI, Same as HNO3.-
KCN, Neg. FeCl3, Same as HNO 3. KOH, Slowly tarnishes brown;
rubs blue.
Hardness, Low. 3.
Description. C.-Cherry-red, tarnishing to violet-blue. Str.--Black.
Massive.
B.B. Roasted and reduced with sodium carbonate on charcoal, yields
copper buttons. Also yields a white coat with metallic-like luster, a
selenium odor, and colors the flame blue (IV, 17, a). Fus.—1.5.
WHITE Clausthalite* PbSe (Very Rare)
Microchem. HNO3, Forms brick-red coating; rubs off to brown surface.
HCI, Slowly tarnishes brown; rubs clean. KCN, Neg.
KCN, Neg. FeCl3, Slowly
tarnishes, forming bluish and yellowish coating. 'KOH, Neg.
Hardness, Low. 2.5-3.
Description. C.-Lead-gray. Str.-Black. Granular masses;
cubic
cleavage.
B.B. Decrepitates in the closed tube. Gives all tests for lead and sel-
enium. (
(See Chap. IV, 10 and 17.) Fus.-2.
GALENA WHITE Galena Pbs
Microchem. HNO3, Quickly blackens; rubs black, with rough surface.
(In some specimens shows effervescence.) HČI, Tarnishes brown;
rubs to gray.
Fumes tarnish. KCN, Neg. FeCl3, Tarnishes brown
to iridescent; rubs brown. HgCl2, Neg. KOH, Neg.
Hardness, Low. 2.5-2.75. Sectile, but slightly brittle. Gray powder.
Description. C. and Str.-Pure lead-gray. Perfect cubic cleavage.
B.B. Yields all tests for lead (IV, 10). Fus.-2.
GALENA WHITE Lillianite* 3PbS.Bi,S, (Very Rare)
Microchem. HNO3, Quickly tarnishes iridescent; rubs clean. HCI,
Slowly tarnishes pale brown; rubs clean. Fumes tarnish. KCN, Neg.
FeCl3, Slowly tarnishes iridescent; rubs clean. KOH, Neg.
Hardness, Low.
Description. C.-Steel-gray. Str.—Blck. Massive, also crystalline.
B.B. With KI & S flux shows both lead and bismuth (IV, 3 and 10).
Fus.—1-1.5.
GRAYISH WHITE Teallite*
PbSnS2
(Very Rare)
Microchem. HNO3, Tarnishes brown to iridescent; rubs clean. HCI,
Slowly tarnishes light brown; rubs clean. Fumes tarnish. KCN, Neg.
FeCl3, Slowly tarnishes faint brown. KOH, Same as FeCl3.
Hardness, Low. 1-2.
Description. C.--Blackish gray. Str.-Black. Thin flexible folia.
Perfect basal cleavage.
B.B. Yields all tests for lead and tin. (See Chap. IV.)
GRAYISH WHITE Cylindrite Pb.Sb2Sn.S21 (Very Rare)
Microchem. HNO3, Slowly tarnishes brown; rubs to iridescence. Fumes
tarnish iridescent. HCÎ, Acid is without effect, but fumes tarnish
brown; rubs to very faint gray. KCN, Neg. FeCl3, Tarnishes brown;
rubs to very faint brown. HgCl2, Neg. KOH, Tarnishes brown to
iridescent; rubs to faint gray.
Hardness, Low. 2.5-3. Very sectile. Gray powder when scratched.
Description. C.-Blackish gray. Str.-Black. Massive; also in cylin-
under pressure.
B.B. See Chapter IV for tests for antimony, tin, and lead. Fus.—1.5.
CREAMY WHITE Native Silver See page 43.
WHITE
Native Antimony See page 96.
77
ANO:
DETERMINATIVE TABLES
HCI
KCNN
Low
FeCl3-N
GALENA WHITE Meneghinite* 4PbS.Sb2S, (Very Rare)
Microchem. HNO3, Quickly tarnishes and blackens; rubs to gray, rough
surface. HCI, Very slowly faint brown to almost negative. KCN,
Neg. FeCl3, Neg. HgCl2, Neg. KOH, Tarnishes very slowly.
Hardness, Low. 2.5. Brittle. Gray powder when scratched.
Description. C.-Blackish gray. Str.-Black. Pinacoidal cleavage.
Slender prismatic crystals; also massive, fibrous, and compact.
B.B. Decrepitates and fuses very easily. Yields antimony flame and
coat on charcoal (IV, a). With KI & S ilux yields lemon-yellow lead
iodide coat (IV, 10 a). Fus.-
1.
GALENA WHITE Geocronite 5PbS.Sb2S. (Very Rare)
Microchem. Same as Meneghinite. Except KOH is negative.
Hardness, Low. 2.5. Brittle. Gray powder when scratched.
Description. C. and Str.—Light lead-gray to grayish blue. Usually
massive, granular, or earthy.
B.B. Like Meneghinite.
GRAYISH WHITE Franckeite Pb Sn Sb 2S12 (Very Rare)
Microchem. HNO3, Tarnishes brown, then iridescent; rubs faint irides-
cent. HCI, Usually tarnishes faint brown. Fumes tarnish slightly.
KCN, Neg. FeCl3, Neg.. HgCl2, Neg. KOH, Practically negative,
but sometimes faintly tarnishes and rubs clean.
Hardness, Low. 2.75. Extremely sectile. Gray powder when scratched.
Description. C.--Blackish grayStr.-Black. One perfect cleavage.
Massive.
B.B. See Chapter IV for tests for lead, tin, antimony, etc. Fus.—1.
WHITE
Eucairite
See page 97.
GRAYISH WHITE
Cylindrite
See page 77.
79
HNO,
DETERMINATIVE TABLES
HCI-N
KCN
Med.
FeCl.
GRAYISH WHITE
POLYBASITE
See page 87.
81
GRAYISH (BROWNISH) WAITE Freibergite (Cu, Ag).Sb2S,
Microchem. HNO3, Slowly tarnishes brown to iridescent; rubs pale.
Fumes tarnish brown. HCI, Neg. KCN, Tarnishes brown to irides-
cent; rubs same. FeCls, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Medium. 3-4.
Description. Similar to tetrahedrite.
B.B. Like tetrahedrite, but contains silver.
82
HNO3
DETERMINATIVE TABLES
HCl-N
KCN
Med.
FeCl3-N
PINKISH WHITE Luzonite CuzAsS (Very Rare)
Microchem. HNO3, Very slowly tarnishes faintly; washes clean. Fumes
tarnish slightly. HCI, Neg. KCN, Slowly tarnishes. FeCl3, Neg.
Hardness, Medium. 3.5. Brittle. Gray or black powder when scratched.
Description. C.--Dark reddish steel-gray. Str.-Black. Massive.
B.B. Like enargite.
BROWNISH WHITE Enargite CuzASSA
Microchem. HNO3, Very slowly tarnishes faint brown; rubs clean.
Fumes slowly tarnish faint brown. HCI, Neg. KCN, Sometimes re-
acts very faintly, but quickly darkens some specimens, rubbing to a
rough etched surface. FeCl3, Neg. HgCl2, Slowly tarnishes brown;
Hardness, Medium. 3. Brittle. Gray powder when scratched.
Description. C. and Str.-Grayish to iron-black. Often seen with pris-
matic planes vertically striated; also massive or disseminated. Colum-
nar cleavage.
B.B. In the closed tube decrepitates, yielding a sublimate of sulphur.
At a higher temperature it fuses and yields a sublimate of arsenic sul-
phide (IV, 2, c). Roasted and reduced with sodium carbonate, yields
a malleable copper button.
PINKISH WHITE Famatinite CusSbS4
Microchem. HNO3, Very slowly tarnishes brown; rubs to brown.
Fumes tarnish faintly. HCI, Neg. KCN, Slowly tarnishes brown
with etching; rubs to pale etched surface.
(Some specimens are prac-
tically negative.) FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Medium. 3.5. Brittle. Gray powder when scratched.
Description. C.-Gray with tinge of copper-red. Str.--Black.
B.B. In the closed tube decrepitates, yielding sublimate of sulphur, and
on higher heating, a sublimate of antimony sulphide (IV,1, c). Re-
duced with fluxes, yields metallic copper and, when moistened with
HCl, yields a blue copper chloride flame (IV, 6). Fus.—1-1.5.
GALENA WHITE Guejarite Cu2Sb487 (Very Rare)
Microchem. HNO3, Tarnishes dark; rubs to gray. HCI, Neg. (Some
specimens tarnish very faintly and rub clean.) KCN, Slowly tarnishes
brown; rubs to a faint brown. FeCl3, Neg. HgCl2, Tarnishes faint
brown; rubs clean. KOH, Quickly tarnishes; rubs to deeply etched
surface.
Hardness, Medium. 3.5. Sectile, but slightly brittle. Gray powder
when scratched.
Description. C.--Steel-gray with tinge of blue. Str.-Black. Prismatic
crystals. Good pinacoidal cleavage.
B.B. Like Famatinite.
ܕ2
YELLOW
Chalcopyrite
GRAYISH WHITE
Tennantite
GRAYISH WHITE
Tetrahedrite
See page 117.
See page 117.
See page 117.
See page 65.
CREAMY WHITE
Sulvanite
83
HNO3
DETERMINATIVE TABLES
HCI-N
KCN
Low
FeCl2
GRAYISH (GREENISH) WHITE Pearcite Ag Ass (Very Rare)
Microchem. HNO3, Acid without effect, but fumes tarnish and wash
clean. HCI, Neg. KCN, Quickly blackens; rubs to gray, roughened
surface. FeCl3, Iarnishes iridescent; rubs to very faint gray. (Some-
times rubs clean.) HgCl2, Tarnishes brown; rubs to iridescent brown.
KOH, Neg.
Hardness, Low. 3. Sectile.
Description. C. and Str.-Black. Tabular crystals and massive.
B.B. Yields arsenic odor and white coat on charcoal (IV, 2, a). Roasted
and reduced with sodium carbonate yields silver buttons. Fus.—-1.
BLUISH WHITE
Polyargyrite
See page 109.
GRAYISH WHITE
Argentite
See page 67.
GRAYISH WHITE
Jalpaite
See page 67.
GRAYISH WHITE
POLYBASITE
See page 87.
85
HNO,
DETERMINATIVE TABLES
HCI-N
KCN
Low
FeCl3-N
GALENA WHITE Stibnite Sb2S;
Microchem. HNO3, Tarnishes dark brown; rubs to gray. HCI, Neg.
KCN, Dissolves, bleaches, and roughens surface, but does not tarnish.
FeCl3, Neg. HgCl2, Neg. KOH, Tarnishes brown and shows yellow
coating; rubs to roughened surface often showing patches of yellow.
Hardness, Low. 2. Slightly brittle. Gray powder when scratched.
Description. C. and Str.-Lead-gray. Crystals are long prisms with
striations Parallel to elongation. Highly perfect "5" pinacoidal
cleavage.
B.B. Yields antimony flame and coat on charcoal (IV, 1, a). When
pure volatilizes entirely. Fus.--1.
GALENA WHITE KERMESITE Sb2S20
Microchem. HNO3, Tarnishes light brown; rubs pale brown. HCI,
Neg. KCN, Slowly tarnishes pale brown; rubs faint. FeCl3, Neg.
HgCl2, Neg. (?). KOH, Tarnishes iridescent and is coated with yellow;
rubs clean.
Hardness, Low. 1-1.5. Very sectile. Red powder when scratched.
Internal reflection as seen by inclined light is red.
Description. C.-Cherry-red. Str.-Brownish-red. Usually in needle-
like crystals.
B.B. In the closed tube blackens, fuses, and at first yields a white sub-
limate of antimony trioxide; after strongly heating yields the usual
black or dark red antimony sublimate in closed tube. Otherwise like
stibnite. Fus.-1.
GRAYISH WHITE POLYBASITE
Ag.SbSo
Microchem. HNO3, Some specimens practically negative. Others
tarnish_very slowly; rubs to faint gray etched surface. HCI, Neg:
KCN, Develops scratches and tarnishes dark brown; rubs to gray etched
surface. Fels, Practically negative, but some specimens tarnish faint
brown; wash clean. HgCl2, Quickly tarnishes brown to black; rubs
to faint brown. KOH, Neg.
Hardness, Low. 2-3. Sectile, but slightly brittle. Gray powder when
scratched. Internal reflection as seen by inclined light is red. (Not
always detected.)
Description. C.-Iron-black, in thin splinters cherry-red. Str.-Black.
B.B. On charcoal fuses with spirting to a globule, yielding antimony
flame and coat (IV, 1, a). Reduced with sodium carbonate yields
silver (IV, 18, a). Fus.-1.
GALENA WHITE
Livingstonite
See page 111.
87
ANO,
DETERMINATIVE TABLES
HCI-N
KCNN
High
FeCl3
WHITE Chloanthite NiAs
Microchem. HNO3, Slowly tarnishes faint brown; rubs to pale gray.
Fumes tarnish. HCl, Ñeg. KCN, Neg. FeCl3, Slowly tarnishes
faint brown, but is often almost negative. HgCl2, Neg. KOH, Neg.
Hardness, High. 5.5-6. Brittle. Gray powder when scratched.
Description. C.-Tin-white. Str.-Gray-black.
B.B. Fuses easily to a globule and yields an arsenic odor and perhaps a
white arsenic coat on charcoal. Yields a red precipitate with dimethyl
glyoxime (IV, 14, 6). Gives a cobalt reaction with borax usually due
to impurities of that element. Fus.—2.
WHITE Rammelsbergite NiAsz (Very Rare)
Like chloanthite in all properties except crystal system.
WHITE GERSDORFFITE NiAss
Microchem. HNO3, Tarnishes brown, then black; rubs to rough gray
surface. Fumes tarnish brown and develop structure. HCI, Mineral
unaffected, but acid turns bright yellow. KCN, Neg. FeCl3,
Slowly tarnishes faint brown. (Sometimes practically negative.)
HgCl2, Tarnishes brown; rubs clean. KOH, Neg.
Hardness, 5.5. Brittle.
Description. C.--Silver-white, tarnishing to gray. Str.--Grayish black.
Good cubic cleavage.
B.B. Decrepitates in the closed tube and yields a yellowish brown sub-
limate (IV, 2, c). Otherwise like chloanthite.
89
HNO3
DETERMINATIVE TABLES
HCI-N
KCN-N
High
FeCl3-N
WHITE
Löllingite
FeAsz
(Very Rare)
Microchem. HNO3, Slowly_tarnished faint brown. Fumes tarnish.
HCI, Neg. KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, High. 5–5.5. Brittle.
Description. C.-Silver-white. Str.-Black.
B.B. Fuses to strongly magnetic globule in R.F. on charcoal. Gives
arsenic coat and odor; also sublimate and mirror in open and closed
tube respectively. Fus.—2.
WHITE Ulmannite* NiSbs (Very Rare)
Microchem. HNO3, Tarnishes brown to iridescent; rubs to iridescent
gray. HCI, Neg. KCN, Neg. FeCl3, Neg. KOH, Neg.
Hardness, High. 5-5.5. Brittle.
Description. C.-Silver-gray. Str.-Grayish black. : Perfect cubic
cleavage.
B.B. On charcoal in the R.F. fuses easily to a globule, boils, and yields
an antimony coat (IV, 1, a). Yields a red precipitate with dimethyl
glyoxime (IV, 14, 6). Fus.—1.5.
CREAMY WATE Linncite Co SA (Very Rare)
Microchem. HNO3, Tarnishes very faint brown. Fumes tarnish brown
very slowly. HČI, Neg. KCN, Neg. FeCl3, Neg. HgCl2, Tar-
nishes iridescent brown. KOH, Neg.
Hardness, High. 5.5. Brittle.
Description. C.-Pale steel-gray, tarnishing copper-red. Str.-Black.
Imperfect cubic cleavage.
B.B. On charcoal fuses to a magnetic globule. The roasted mineral
yields with the fluxes reactions for nickel, cobalt, and iron usually.
Fus.--2.
PINKISH WHITE GLAUCODOT (Co,Fe) Ass (Rare
Microchem. HNO3, Slowly tarnishes; rubs to rough gray surface. HCI,
Neg. KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOÅ, Neg.
Hardness, High. 5. Brittle.
Description. C.-Gray. Str.—Black. Usually prismatic crystals or
B.B. Yields arsenic odor and coat on charcoal, etc. (IV, 2). In the
R.F. fuses to a feebly magnetic globule, black on the surface, but a
light bronze in color when freshly fractured. Fus.-2-3.
Hauchecornite (Ni,Co),(S.Sb.Bi): (Very Rare)
Microchem. HNO3, Very slowly 'tarnishes brown; rubs to very pale
brown. Fumes tarnish slightly. HCI, Neg. KCN, Neg. FeCl3,
Neg. HgCl2, Slowly tarnishes brown; rubs clean. KÓH, Ñeg.
Hardness, High to medium. 5. Very Brittle. Steel-gray powder when
scratched.
Description. C.-Light bronze-yellow. Str.-Biack.
B.B. Yields common reactions for constituents indicated in formula.
(See Chapter IV.)
massive.
CREAM
WHITE
WHITE
WHITE
CREAMY WHITE
CREAM
GERSDORFFITE
Chloanthite
Willyamite
Pyrite
Pyrrhotite
See page 89.
See page 89.
See page 57.
See page 57.
See page 95.
91
HNO3
DETERMINATIVE TABLES
HCI-N
KCN-N
Med.
FeCls
PINK Breithauptite
NiSb (Very Rare)
Microchem. HNO3, Blackens; rubs to dark gray. HCI, Neg: KCN,
Neg. FeCla, Tarnishes; rubs to clean-pitted surface. KOH, Neg.
Hardness,, Medium to high. 5.5.? Brittle. Reddish-brown powder
when scratched.
Description. C.-Light copper-red. Str.-Reddish brown.
B.B. Yields antimony flame and coat on charcoal and with dimethyl
glyoxime gives a red precipitate. (IV, 14, 6).' Fus.-1.5-2.
93
GRAYISH WHITE BOURNONITE (PbCu)3Sb2S6 (Rare)
Microchem. HNO3, Fumes usua
HNO, Fumes usually tarnish slowly; rubs clean. HCI,
Neg. KCN, Neg. FeCla, Neg. HgCl2, Tarnishes faintly at edge
of drop; rubs to very faint brown. KOH, Neg.
Hardness, Medium to low. 2.5-3. Slightly brittle.
Description. C.-Steel-gray. Str.-Black.
B.B. In the closed tube decrepitates and gives a dark red sublimate.
Yields antimony flame and coat on charcoal; with continued heating,
yielding a lead coat. Residue reduced with sodium carbonate yields
copper buttons. Fus.--1.
GRAYISH WHITE Stylotypite 3(Cu,Ag,Fe)S.Sb2S, (Very Rare)
Microchem. HNO3, Tarnishes brown very slowly; rubs faint or clean.
Fumes tarnish. HCI, Neg. KCN, Neg. FeCl3, Neg. HgCl2, Neg.
KOH, Neg.
Hardness, Medium. 3. Brittle.
Description. C. and Str.-Iron-black.
B.B. Decrepitates and fuses easily, yielding a steel-gray, magnetic glob-
ule. Also tests for constituents in formula. Fus. -1.5.
GRAYISH WHITE Stannite SnCu Fes (Very Rare)
Microchem. HNO3, Tarnishes brown to iridescent; rubs to very faint
brown. HCI, Neg. KCN, Neg. FeCla, Neg. HgCl2, Neg. KOH,
Neg.
Hardness, Medium. 4. Brittle.
Description. C.-Steel-gray. Str.-Black. Massive, granulur, or dis-
seminated.
B.B. In the closed tube decrepitates, giving a faint sublimate only.
See Chapter IV for tests for constituents of the mineral.
GRAYISH WHITE Crookesite* (CuTiAg)2Se (Very Rare)
Microchem. HNO3, Slowly tarnishes faint brown; rubs clean. Fumes
tarnish. HCI, Neg. KČN, Neg. FeCl3, Neg. KOH, Neg.
Hardness, Medium to low. 2.5-3. Brittle.
Description. C.-Lead-gray. Str.-Black. Massive, compact.
B.B. Fuses easily to greenish black, shining enamel, coloring flame blue.
Roasted and reduced with sodium carbonate yields copper and silver.
(IV, 6, and 18.) Fus.--1.
GRAYISH WHITE Hauerite MnS2 (Very Rare)
Microchem. HNO3, Fumes tarnish brown very slowly; washes clean.
HCI, Neg. KCN, Neg. FeCla, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Medium.'4. Brittle. Brick-red powder when scratched.
Description. C.-Brownish black. Str.-Reddish brown.
B.B. Roasted mineral yields green bead with sodium carbonate. Fus.
-3.
GRAY Sphalerite Zus
Microchem. HNO3, Tarnishes faintly brown; rubs clean. HCI, Neg.
KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Medium. 3.5-4. Brittle. Yellow or brown powder when
scratched.
Internal reflection as seen by inclined light is yellow or brown.
Description. C.-Shades of yellow, brown to black. Str.-.Pale to
colorless. Perfect dodecahedral cleavage.
B.B. Nearly infusible. Reduced with soda on charcoal yields white
zinc oxide coat, which when moistened with cobalt nitrate sol. and
again heated in the O.F. becomes green (IV, 29, a).
Wurtzite is like sphalerite physically
and microchemically.
YELLOW
Chalcopyrite
Sulvanire
CREAMY WHITE
See page 117.
See page 65.
See page 83.
See page 116.
PINKISH WHITE
FAMATINITE
GRAY
Voltzite
94
HNO,
CREAM
CREAM
HCI -N
DETERMINATIVE TABLES
KCN-N
Med,
FeCl3-N
PALE YELLOW MILLERITE Nis (Rare,
Microchem. HNO3, Acid is without effect, but fumes tarnish brown;
rubs to very faint brown. HCI, Neg. KCN, Neg. FeCl3, Neg.
HgCl2, Tarnishes brown; rubs clean. KOH, Neg.
Hardness, Medium. 3-3.5. Brittle. Grayish yellow powder when
scratched.
Description. C.--Bronze-yellow. Str.-Greenish black. Commonly
occurs as hair-like crystals or botryoidal crusts. At least two perfect
cleavages.
B.B. On charcoal in the R.F. the roasted mineral gives a coherent
metallic mass, slightly magnetic. As well as yielding reactions for
nickel, most varieties also show copper, cobalt, and iron. Fus.-2.
Pyrrhotite
FeS(S)x
Microchem. HNO3, Tarnishes very slowly faint brown; almost negative;
rubs clean. Fumes tarnish brown. HCI, Neg. (Humes sometimes
tarnish faintly.). KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOH,
Slowly tarnishes brownish or iridescent; rubs to brownish iridescence.
Hardness, Medium. 3.5-4.5. Brittle.
Description. C.-Bronze-yellow. Str.-Grayish-black. Usually mas-
sive or disseminated. Naturally magnetic.
B.B. In the R. F. on charcoal blackens and becomes strongly magnetic.
Fus.--2.5-3,
Chalmersite CuFeS. (Very Rare)
Microchem. HNO3, Fumes tarnish slightly; washes clean. HCI, Neg.
KCN, Neg. FeCl, Neg. HgCl, Neg. KOH, Neg.
Hardness, Medium. 3.5. Slightly brittle.
Description. C.--Pale yellow. Str.-Grayish or greenish black.
Strongly, though variably magnetic.
B.B. In the R.F. on charcoal fuses to a strongly magnetic globule. Well
roasted and reduced with sodium carbonate on charcoal yields cop-
per (IV, 6, a).
CREAMY WHITE PENTLANDITE (Fe, Ni)s (Rare)
Microchem. HNO3, Slowly tarnishes very faint brown; rubs to very
faint brown. HČI, Neg. KCN, Neg. FeCl3, Neg. HgCl2, Neg.
Hardness, Medium. 3.5-4. Brittle.
Description. C.-Light bronze-yellow. Str.--Bronze. Non-magnetic.
Massive.
B.B. Fuses readily to a magnetic globule on charcoal and yields a red
precipitate with dimethyl glyoxime (IV, 14, b). Fus.—2.
CREAMY WHITE Wittichenite CuzBiS: (Very Rare)
Microchem. HNO3, Tarnishes light brown; rubs to gray. Fumes
tarnish. HCl, Neg. KCN, Neg. FeCl3
, Neg. HgCl2, Neg. KOH,
Slowly tarnishes faint brown; rubs clean.
Hardness, 3.5. Slightly brittle.
Description. C.-Steel-gray. Str.-Black.
B.B. On charcoal fuses easily, at first throwing out sparks, and yielding
a bismuth oxide coat (IV, 3, a). The roasted material, moistened with
HCl yields a strong blue copper chloride flame, Fus.-1.
GALENA WHITE Andorite Pb AgSb S6 (Very Rare)
Microchem. HNO3, Slowly tarnishes brown or iridescent; rubs faint or
clean. Fumes tarnish slowly. HCI, Neg. KCN, Neg. FeCl3, Neg.
HgCl2, Neg. KOH, Slowly tarnishes to pale brown; rubs to faint
brownish iridescence.
Hardness, Medium to low. Brittle.
Description. C.-Steel-gray. Str.-Black.
B.B. Shows lead and antimony as in bournonite, but when cupelled
yields silver. Fus.-1.
GRAYISH WHITE Tennantite See page 117.
95
WHITE Native Antimony Sb
Microchem. HNO3, Tarnishes brownish or iridescent; rubs same. HCI,
(Sometimes appears to tarnish very faintly.) KCN, Neg.
FeCl3, Tarnishes slowly brown; rubs to pale brown. HgCl2, Slowly
Fe,
tarnishes faintly brown; rubs nearly clean. KOH, Neg.
Hardness, Low. 3.3-5. Very brittle.
Description. C. and Str.--Tin-white. Perfect cleavage.
B.B. On charcoal
yields a white coat in both R.F. and O.F.; with inter-
mittent blowing the globule is finally crusted over with prismatic
crystals of antimony trioxide.
CREAMY WHITE Native Silver See page 43.
GALENA WHITE
See page 43.
Plagionite
Aguilarite
GRAYISA WHITE
See page 76.
96
HNO3
HCI-N
DETERMINATIVE TABLES
KCN-N
Low
FeCl3
WHITE Berzelianite Cu Se (Very Rare)
Microchem. HNO3, Tarnishes iridescent; rubs to iridescent greenish
gray. HCI, Neg. KCN, Neg. FeCl3, Tarnishes very light brown;
rubs clean. HgCl2, Tarnishes very light brown; rubs clean. KOH,
Neg.
Hardness, Low. Very sectile.
Description. C.-Silver-white, soon tarnishing. Str. --Shining. Occurs
in thin dendritic crusts and disseminated.
B.B. In the open tube gives a red sublimate of selenium, with white
crystals of selenium dioxide. On charcoal yields white coat, selenium
odor, and blue flame; with soda in R.F. gives metallic copper. Fus.-
1.5.
WHITE Eucairite Cu Se. AgzSe
(Very Rare)
Microchem. HNO3, Tarnishes black and shows orange coating; rubs to
rough gray. Fumes tarnish slightly. HCl, Neg. KCN, Neg. FeCl3
,
Practically negative. (Sometimes tarnishes very slowly faint brown.)
HgCl2, Neg. KOH, Neg.
Hardness, Low. 2.5. Very sectile.
Description. C.-Silver-gray. Str.-Shining. Massive and granular.
B.B. Like berzelianite except that silver is shown on reduction.
CREAMY WHITE Kalgoorlite HgAu2Ag&Tec? (Very Rare)
Microchem. HNO3, Very slowly tarnishes faint brown; rubs almost
clean. HCI, Neg. KËN, Neg. FeCl3, Tarnishes iridescent; rubs to
rough brownish surface. HgCl, Neg.. KOH, Neg.
Hardness, Low. Sectile, but slightly brittle.
Description. C. and Str.-Iron-black. Occurs massive.
B.B. Yields tellurium flame and coat on charcoal (IV, 20, a). Roasted
and reduced with sodium carbonate yields gold and silver. With soda
in a closed tube gives metallic mercury.
GRAYISH WHITE Petzite (Ag, Au)2Te (Very Rare)
Microchem. HNO3, Tarnishes brown to black; rubs gray. (Some
specimens effervesce.) HCl, Neg. KCN, Neg. FeCl3
, Tarnishes
brown; rubs clean. HgCl2, Tarnishes light brown; rubs faint. KOH,
Neg.
Hardness, Low. 2.5-3. Very sectile.
Description. C.-Iron-black. Str.-Gray. Granular to compact.
B.B. Yields a bright green tellurium fláme and white coat on charcoal
(IV, 20, a). Roasted and reduced with soda on charcoal yields gold
and silver button. Fus.—1.5.
GRAYISH WHITE Coloradoite Hg Te (Very Rare)
Microchem. HNO3, Slowly tarnishes iridescent; rubs clean. HCI, Neg.
KCN, Neg. FeCl3, Tarnishes very faint brown; rubs clean. HgCl2,
Neg. KOH, Neg.
Hardness, Low. 3. Very sectile.
Description. C.-Iron-black. Str.-Black. Massive; granular.
B.B. Easily volatile on charcoal. In the closed tube slightly decrepi-
tates, fuses and yields metallic mercury, also tellurium oxide in drops,
and next to the assay metallic tellurium. Fus.—1.
GRAYISH WHITE Molybdenite MoS2.
Microchem. HNO3, Slowly very faint tarnish; rubs clean. Fumes
tarnish faint. (Reaction is often practically negative.) HCI, Neg.
KCN, Neg. FeCl3, Practically negative, but sometimes tarnishes very
faint brown; washes clean. HgCl2, Neg. KOH, Neg.
Hardness, Low. 1-1.5. Very sectile.
Description. C.--Lead-gray to bluish black. Str.-Bluish gray. Marks
paper. Laminæ are flexible, but inelastic. Perfect basal cleavage.
B.B. Infusible, but yields a green flame, also a white coat in O.F. on
charcoal (IV, 13).
97
GALENA WHITE Galenobismutite* Pb Bi SA (Very Rare)
Microchem. HNO3, Tarnishes brown to black; rubs same. HCI, Neg.
KCN, Neg. FeCl3, Neg. KOH, Neg.
Hardness, Low. 3-4.
Description. C.-Lead-gray to tin-white. Str.-Grayish black.
B.B. With KI & S flux shows both lead and bismuth (IV, 3, and 10).
GALENA WHITE Beegerite* Pb.Bi2S, (Very Rare)
HNO3, Tarnishes; rubs to faint gray. Fumes tarnish.
HCl, Neg. KCN, Neg. FeCl3, Neg. KOH, Neg.
Hardness, Low.
Description. C.-Gray. Str.-Grayish black.
B.B. Like galenobismutite.
GALENA WHITE Freieslebenite (Pb,Ag2).Sb.Su (Very Rare)
Microchem. HNO3, Tarnishes dark; rubs to rough gray. One fairly
reliable specimen of_this mineral was negative with HNO 3. HCİ,
Neg. KČN, Neg. FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Low. 2-2.5. Brittle.
Description. C.-Steel-gray. Str.—Black. Vertically striated prisms.
B.B. Yields antimony filame and coat on charcoal (IV, 1, a). With
KI & S flux shows lead (IV, 10, a). Reduced with soda and cupelled
shows silver. Fus.—1.
GALENA WHITE Nagyagite
Au2Pbı Sb Te&Sus? (Very Rare)
Microchem. HNO3, Slowly tarnishes iridescent; rubs gray. HCÍ, Neg.
KCN, Neg. FeCl3, Neg. HgCl2, Neg. KOH, Neg.
Hardness, Low. 1-1.5.
Description. C.-Gray. Str.—Black. One perfect cleavage. Thin
laminæ are flexible. Tabular crystals; also granular massive.
B.B. Complex, but yields tests for constituents of formula. (See
Chap. IV.)
CREAMY WHITE
Sylvanite AuAgTez (Very Rare)
Microchem. HNO), Tarnishes brown; rubs to deep brown, sometimes
developing cleavage. HCI, Neg. KCN, Neg. FeCl3, Neg. HgCl2,
Neg. KOH, Neg.
Hardness, Low. 1.5-2. Slightly brittle.
Description. C.-Yellowish steel-gray. Str.-Gray. Perfect pinacoidal
cleavage. Usually crystalline.
B.B. Yields bright green tellurium flame and coat on charcoal (IV, 20,
a). Roasted and reduced with soda yields both gold and silver.
Fus.—1.
CREAMY WHITE Guanajuatite BizSez (Very Rare)
Microchem. HNO3, Quickly tarnishes iridescent; rubs practically clean.
Fumes tarnish brown. HCI, Neg. KCN, Neg. FeCl3, Neg. HgCl2,
Slowly tarnishes brown; rubs clean. KOH, Neg.
Hardness, Low. 2.5-3.5.' Sectile to slightly brittle.
Description. C.-Bluish gray. Str.-Black.
B.B. Yields blue selenium flame, odor, and coat on charcoal (IV, 17, a).
With KI & S ilux yields a brick-red bismuth iodide coat (IV, 3).
Fus.—1.5.
98
HNO,
DETERMINATIVE TABLES
HCI-N
KCN-N
Low
FeCl3-N
PALE BROWN Sternbergite* AgFe2S3? (Very Rare)
Microchem. HNO3, Tarnishes iridescent; rubs gray. HCI, Neg. KCN,
Neg. FeCl3, Neg. KOH, Tarnishes brown; rubs clean.
Hardness, Low. 1-1.5.
Description. C.-Bronze. Str.–Black. Perfect basal cleavage. Lam-
inæ are flexible, like tin-foil. Marks paper. Tabular crystals.
B.B. Roasted on charcoal becomes magnetic and the surface of the glob-
.
GALENA WHITE Lengenbachite Pb (AgCu),As S12 (Very Rare)
Microchem. HNO3, Practically negative, but sometimes tarnishes
slightly; rubs to faint gray. HCI, Neg. KCN, Neg. FeCl3, Neg.
HgCl2, Neg. KOH, Neg.
Hardness, Low. Brittle.
Description. C.-Steel-gray. Str.–Brownish. Marks paper.
B.B. Yields arsenic odor and coat on coal (IV, 2, a). See Chapter IV.
GALENA WAITE Rathite Pb(As, Sb)S? (Very Rare)
Microchem. HNO3, Very slowly tarnishes brown; rubs to faint_gray.
Sometimes practically negative. HCI, Neg. KCN, Neg. Fecis,
Neg. HgCl2
, Neg. KOH, Tarnishes brown; rubs to faint gray.
Hardness, Low. Brittle.
Description. C.-Blackish lead-gray. Str.—Reddish brown. Prismatic
cryst.
B.B. Yields common tests for constituents in formula. (Chap. IV).
GALENA WHITE Jordanite* Pb4As2S1 (Very Rare)
Microchem. HNO3, Tarnishes slightly; rubs clean. HČI, Neg. KCN,
Neg. FeCl3, Neg. KOH, Neg.
Hardness, Low. 3. Brittle.
Description. C.-Lead-gray. Str.-Black. Six sided crystals.
B.B. Decrepitates strongly yielding arsenic odor and white coat on char-
coal; also a yellow lead oxide coat near the assay. Fus.--1.
GALENA WHITE Guitermanite* 3PbS.As2S3? (Very Rare)
Microchem. HNO3, Quickly tarnishes iridescent; rubs clean. HCI,
Neg. KCN, Neg. FeCla, Neg.. KOH, Neg.
Hardness, Low. 3.
Description. C.--Bluish gray. Str.---Black. Massive, compact.
B.B. Like jordanite.
GALENA WHITE Epiboulangerite* Pb3Sb2S. (Very Rare
Microchem. HNO3, Tarnishes black; rubs to gray. Sometimes shows
small white crystals after rubbing. HCI, Neg. (Fumes sometimes
tarnish slightly.) KCN, Neg. FeCls, Neg. KOH, Neg.
Hardness, Low.
Description. C.-Dark bluish gray. Str.-Black. Striated prismatic
needles.
B.B. Yields antimony flame and coat on charcoal (IV, 1, a); also yellow
lead oxide coat near the assay. Fus.-1.
WHITE
WHITE
CREAMY WHITE
GALENA WHITE
GALENA WHITE
GRAYISH WHITE
GRAYISH WHITE
GRAYISH WHITE
GALENA WHITE
Eucairite
Berzellianite
Emplectite
Stibnite
Geocronite
Crookesite
Regnolite
JAMESONITE
Andorite
See page 97.
See page 97.
See page 63.
See page 87.
See page 79.
See page 94.
See page 119.
See page 62.
See page 95.
99
HNO3-N
DETERMINATIVE TABLES
HCI
KCN
Low
FeCl2
GRAYISH WHITE STEPHANITE Ag.SbS4
Microchem. HNO3, Neg. HCI, Fumes slowly tarnish brown to irides-
cent; rubs clean. KCN, Quickly tarnishes brown; rubs pale brown,
developing cracks. FeCl,
Slowly gives a speckled surface; rubs clean
HgCla, Quickly tarnishes brown; rubs to brown. KOH, Slowly tar-
nishes deep brown; rubs clean.
Hardness, Low. 2-2.5. Slightly sectile to brittle.
Description. C. and Str.--Iron-black.
B.B. In the closed tube decrepitates and fuses, after long heating giving
faint antimony sublimate. On charcoal fuses easily with spirting,
yielding a white coat which may become red with oxidized silver.
Roasted and reduced with soda yields silver button.
BROWN Pyrolusite
MnO2
Microchem. HNO3, Practically negative. (Faintly tarnishes and dis-
solves in two or three minutes.) HCl, Tarnishes slowly; rubs pale.
KCN, With 20 per cent. solution almost negative, but rapidly tarnishes
with very dilute solution and is noticeable usually after washing.
FeCl3, Tarnishes dark brown; rubs pale. HgCl2, Neg. KOH, Neg.
Hardness, Low (Variable).
Description. C.-Dark steel-gray to iron-black. Str.—Black. Soils
fingers.
B.B. Infusible. Yields manganese reactions with the fluxes. Evolves
chlorine when treated with HCI.
GRAYISH WHITE
Jalpaite
See page 67.
BLUISH WHITE
Proustite
See page 109.
101
HNON
DETERMINATIVE TABLES
HCI
KCN-N
Med.
FeClz-N
GRAYISH WHITE (CREAMY) Delafossite CuO, Fe2O3? (Very Rare)
Microchem. HNO3, Neg. HCI, Tarnishes slightly and acid turns yel-
lowish-green; rubs to etched surface. KČN, Neg. FeCl3, Neg.
HgCl2, Neg. KOH, Neg.
Hardness, Medium. 2.5. Brittle.
Description. C.-Dark gray. Str.-Blackish gray. Cleavable in to
laminæ. Occurs in small crystalline plates.
B.B. Fusible with difficulty, coloring the flame green. Easily soluble
in HCI.
103
HNO3-N
DETERMINATIVE TABLES
HC1-N
KCN
Med.
FeCl2
GRAYISH WHITE
POLYBASITE
See page 87.
105
HNON
DETERMINATIVE TABLES
HC1-N
KCN
Med.
FeCl3-N
YELLOW
BROWNISH WHITE
GRAYISE WHITE
Chalcopyrite
Enargite
PYRARGYRITE
See page 117.
See page 83.
See page 111.
107
HNO3-N
DETERMINATIVE TABLES
HCl-N
KCN
Low
FeCl2
BLUISH WHITE Proustite AgzAss
Microchem. HNO3, Neg. HČI, Neg. Fumes sometimes tarnish
faintly; rubs clean. KCN, Slowly tarnishes brown, developing
scratches; rubs to faint brown. FeCl3
, Slowly tarnishes faintly;
rubs clean. HgCl2, Slowly tarnishes brown; rubs to brownish irides-
cence. KOH, Quickly tarnishes black; rubs to pale brown.
Hardness, Low. 2.5. Slightly brittle. Blood-red powder when
scratched.
Internal reflection as seen by inclined light is bright red.
Description.-C. and Str.Scarlet. Commonly as elongated crystals.
B.B. Yields arsenic odor and white coat on charcoal., Prolonged heating
in the 0.F, or reduction with soda in the R.F. yields silver. Fus.-1.
BLUISH WHITE Polyargyrite* Ag24Sb2S16 (Very Rare)
Microchem. HNO3, Neg: Fumes often tarnish slightly; rubs clean.
HCI, Neg. KCN. Quickly tarnishes brown; rubs clean. FeCls,
Tarnishes dark or iridescent; rubs clean. KOH, Neg.
Hardness, Low. 2.5. Very sectile.
Description. C.-Iron-black to grayish black. Str.-—Black. Cubic
cleavage.
B.B. Fuses easily on charcoal to a black globule, giving antimony flame
and coat, and finally a brittle globule of silver. Fus.-1.
GRAYISH WHITE Cerargyrite Agci
Microchem. HNO3, Neg. HCI, Neg. KCN, Quickly tarnishes to red-
dish brown; washes to dark solution pit. FeCl3, Quickly tarnishes
dark brown; rubs same. HgCl2, Neg. KOH, Slowly tarnishes; rubs
pale.
Hardness, Low. 1-1.5. Highly sectile.
Description. C. -Pearl-gray, various. Str.---Waxlike.
B.B. Fuses in closed tube without decomposition. On charcoal gives a
globule of metallic silver.
GRAYISE WHITE Bromyrite AgBr (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Tarnishes slightly; rubs
nearly clean. FeCl3, Tarnishes dark gray to brown; rubs same. HgCl2,
Slight tarnish? KOH, Tarnishes rapidly and forms whitish coating.
Hardness, Low. Sectile.
Description. C.-Bright yellow to grass or olive green. Str.-Yellowish
green. No cleavage.
B.B. On charcoal emits bromine vapors and yields a globule of metallic
silver. In the closed tube reacts like cerargyrite.
Embolite, Ag(CI, Br), and iodobromite, 2AgCl.2AgBr.AgI, are intermediate
between cerargyrite, bromyrite and iodyrite in all chemical and physical
properties as well as in composition. The differences in color on the
polished surface are usually enough to distinguish between any two
that may be present together, and the difference in the rates of reaction
with any of the active reagents easily brings out contrasts between
them.
GRAYISH WHITE Jalpaite See page 67.
GRAYISH WHITE Pearcite See page 85.
109
BLUISH WHITE Miargyrite AgSbS2 (Very Rare)
Microchem. Like pyrargyrite.
Hardness, Low. 2-2.5. Brittle. Cherry-red powder when scratched.
Internal reflection as seen by inclined light is deep red.
Description. C.-Iron-black to steel-gray. Str. —Cherry-red.
B.B. On charcoal fuses quietly, giving a white antimony coat and a
gray bead, which after continued treatment in the O.F. leaves a bright
globule of silver. Fus.—1.
GRAYISH WHITE Argyrodite
Ag&Gesc? (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Tarnishes brown, devel-
oping scratches; rubs to very faintly etched surface. FeCl3, Neg.
HgCl2
, Tarnishes brownish iridescent; rubs to iridescence. KOÉ,
Neg.
Hardness, Low. 2.5. Brittle.
Description. C.-Steel-gray on a fresh fracture, with a tinge of reddish
violet. Str.--Grayish black.
B.B. In the closed tube yields a brilliant black sublimate; in the open
tube fumes of sulphur dioxide. On charcoal fuses to a bead, giving
near the assay a faint white sublimate; after long heating, an orange-
yellow sublimate and a silver globule. Fus.---1.5.
GRAYISH WHITE ORPIMENT As2S2
Microchem. HNO3, Neg. HCI, Neg. KCN, Tarnishes dark quickly;
rubs nearly same. FeCl3
, Neg. HgCl2, Yellow coat, rubs clean.
KOH, Quickly tarnishes black.
Hardness, Low. 1.5-2. Sectile. Lemon-yellow powder when scratched.
Internal reflection as seen by inclined light is yellow.
Description. C.-Lemon-yellow. Str.–Pale yellow. Usually in foli-
ated or columnar masses. Perfect pinacoidal cleavage.
B.B. On charcoal fuses and volatilizes entirely, yielding arsenic odor.
In the closed tube, fuses, volatilizes, and gives a dark yellow sublimate.
Fus.-1.
GRAYISH WHITE Iodyrite AgI (Very Rare)
Microchem. HNO3, Neg. HČI, Neg. KCN, Quickly dissolves and
tarnishes to dark surface; rubs to gray, etched surface, FeCls
, Neg.
HgCl2, Tarnishes brownish to iridescent; rubs same or slightly lighter.
KÓH, Very slowly yields slight tarnish.
Hardness, Low. Sectile. Internal reflection seen by inclined light is yel-
lowish to brownish.
Description. C.--Yellow to yellowish green, sometimes brownish. Str.
Yellow. Perfect C cleavage.
B.B. In the closed tube fuses and assumes a deep yellow color, but re-
sumes its yellow color on cooling. On charcoal gives fumes of iodine
and a globule of metallic silver.
110
HNO3-N
DETERMINATIVE TABLES
HCI-N
KCN
Low
FeC1,-N
BLUE Covellite Cus
Microchem. HNO3, Neg. HCI, Neg.. KCN, Quickly tarnishes purple;
rubs to grayish, deeply etched surface. Fels, Neg. HgCl2, Ñeg.
KOH, Neg.
Hardness, Low. 1.5-2. Slightly brittle.
Description. C.-Deep indigo-blue. Str.-Gray to black. Perfect
basal cleavage; flexible in thin leaves. Common in smaller quantities
as a secondary mineral in nearly all copper deposits.
B.B. On charcoal burns with a blue flame, fusing to a globule which
reacts like chalcocite (IV, 6). Fus.—2.5.
YELLOW Native Gold Au
Microchem. HNO3, Neg. HCI, Neg. KCN, Slowly blackens; rubs to
brownish, rough surface. FeCl3, Neg. (?). HgCl2, Neg. KOH, Neg.
Hardness, Low. 2.5-3. Sectile." Yellow powder when scratched.
Description. C. and Str.-Gold-yellow.
B.B. Fuses easily to yellow button. 'Not acted on by any of the fluxes.
GALENA WHITE Livingstonite HgSb St (Very Rare)
Microchem. HNO3, Neg. (?) HCI, Neg. KCN, Slowly tarnishes
grayish. FeCl3, Neg. HgCl2, Tarnishes to brownish iridescence; rubs
same. KOH, Neg.
Hardness, Low. 2. Red powder when scratched.
Internal reflection as seen by inclined light is deep red.
Description. C.—Lead-gray. Str.-Red. Usually in slender prismatic
crystals.
B.B. Roasted on charcoal is completely volatile. Yields antimony
flame and coat (IV, 1, a). With soda in the closed tube yields mercury
(IV, 12, a). Fus. -1.
BLUISH WHITE Onofrite Hg(SSE) (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Faintly tarnishes brown
or bluish, differentially; rubs to faint brown. Fečls, Neg. HgCl2,
Neg. KOH, Neg. Hardness, Low. 2.5. Sectile to slightly brittle.
Some flakes show yellow internal reflection as seen by inclined light.
Description. C. and Str.-Blackish gray. Massive; fine granular.
B.B. In the closed tube decrepitates and gives sublimates of sulphur
and mercury (IV, 12, a). On charcoal gives copious fumes with selen-
ium odor and a sublimate with metallic-like luster which touched by the
R.F. disappears, coloring the flame azure-blue.
GRAYISH WHITE PYRARGYRITE AgzSbS
Microchem. HNO3, Neg. HCI, Neg. KCN, Tarnishes pale brown
slowly; rubs to faint gray surface showing structure. FeCla, Neg.
HgCl2, Slowly tarnishes light brown; rubs clean. KOH, Tarnishes
black; rubs to speckled yellowish gray surface.
Hardness, Low. 2.5. Brittle. Blood-red powder when scratched.
Internal reflection as seen by inclined light is brilliant red.
Description. C.--Black to grayish black. Str.-Purplish red.
B.B. On charcoal fuses with spirting to a globule, coats the coal white,
and the assay is converted into silver sulphide, which, treated in the
O.F., or with soda in the R.F., gives a globule of silver. Fus.-1.
BLUISH WHITE Proustite See page 109. (Very Rare)
GRAYISH WHITE POLYBASITE See page 87.
111
HNO3-N
DETERMINATIVE TABLES
HC1-N
KCN-N
High
FeCl,
GRAY Uraninite Uranate of U,Pb, etc.
(Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. FeCl. Slowly
tarnishes to still darker brownish gray; rubs same. HgCl2, Neg.
KOH, Neg.
Hardness, High. 5.5. Brittle.
Description. °C.--Pitch-black to greenish. Str.--Greenish brown to
black. Usually massive and botryoidal.
B.B. Infusible. In the R.F. gives a green bead with both borax and
salt of phosphorous (IV, 26, a). Many impurities are always present
and any or all may yield reactions.
113
GRAYISH WHITE WOLFRAMITE (Fe Mn) WO
Microchem. Negative with all reagents.
Hardness, High. 5–5.5. Brittle.
Description. C.-Dark brown to nearly black. Str.—Reddish or
brownish to nearly, black. Perfect pinacoidal cleavage. Crystals
commonly tabular, bladed, columnar, etc.
B.B. Fuses to a magnetic globule with a crystalline surface. With soda
yields a green manganate bead (IV, 11, a). For tests for tungsten, see
ÍV, 25. Fus.--3.
(Note. Hübnerite, Mn WO4, and Ferberite, FeW04, differ from Wol-
framite only in color.)
SnO2
GRAY CASSITERITE
Microchem. Negative with all reagents.
Hardness, High. 6-7.
Description. C.-Brown to black; variable. Str.-Light.
B.B. Infusible. Reduced with soda and borax on charcoal yields metal-
lic tin buttons.
GRAY (VARIABLE) Limonite 2Fe2O3.3H,(?
Microchem. . Negative with all reagents.
Hardness, High.5-5.5. Brittle. Yellow powder when scratched.
Internal reflection as seen by inclined light is often reddish brown.
Description. C.-Ocher-yellow to brownish black. Str.-Yellowish
brown. Never crystallized. Usually botryoidal, concretionary, mas-
sive, earthy, etc.
B.B. 'Infusible. Yields water when heated in the closed tube. Other-
wise like hematite.
(Note.-Göthite, Fe2O3.H,O, and Turgite, 2Fe2O3.H,0, behave chemically
like Limonite, but Turgite is very much lighter in color.)
GRAY
CHROMITE
FeCr204
Microchem. Negative with all reagents.
Hardness, High. 5.5.
Description. C.-Iron-black to brownish black; various. Str. -Brown.
Commonly massive;
fine granular to compact.
B.B Infusible in 0.F., but in R.F. is slightly rounded on edges and
becomes magnetic. For tests for chromium see IV, 4.
GRAYISH WHITE Rare Earths
Columbite, Tantalite, Samarskite, etc., are all chemically inert with the
reagents used and are indistinguishable on polished sections.
GRAYISH WHITE MANGANESE OXIDES
MANGANITE, Mn2O3.H20, HAUSMANNITE, MnO.Mn208, and BRAUNITE,
3Mn203. MnSiO3, are all chemically inert with the reagents used.
114
HNO3-N
HCI-N
DETERMINATIVE TABLES
KCN-N
High
FeCiz-N
WHITE Sperrylite PtAsz (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. FeCla, Neg.
HgCl2, Neg. KOH, Neg.
Hardness, High. 6–7. Brittle,
Description. C.-Tin-white. Str.-Black. In minute isometric
crystals.
B.B.. Decrepitates slightly.. Unchanged in the closed tube. Yields
white arsenic trioxide sublimate in the open tube. Dropped on red-
hot platinum foil, melts, gives off arsenic trioxide fumes, and deposits
porous platinum on the foil. Fus.—2.
PINKISH WHITE Cobaltite CoAss
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. (Sometimes slowly
faint tarnish rubs clean.) Fels
, Neg. HgCl2, Neg. KOH, Neg.
Hardness, High. 5.5. Brittle.
Description. C.-Silver-white, inclined to pinkish. Str.—Grayish black.
Good cubic cleavage. Often in cubic crystals.
B.B. Unaltered in the closed tube. On charcoal yields an arsenic coat
and fuses to a magnetic globule. When well roasted it yields a blue
bead with borax. Fus.—2-3.
CREAMY WHITE Hematite Fe2O.
Microchem. Negative with all reagents.
Hardness, High. 5.5-6.5. Brittle. Brownish red to gray powder when
scratched.
Description. C.—Reddish brown, steel-gray, to iron-black. Str.-
Cherry-red.
B.B. Infusible. On charcoal in R. F. becomes magnetic.
GRAYISH WHITE Magnetite Fe:04
Microchem. Negative with all reagents.
.
Hardness, High. 5.5-6.5. Brittle.
Description. C.--Iron-black. Str.-Black. Naturally strongly mag-
netic.
B.B. Nearly infusible. In the O.F. loses its magnetism. With the
fluxes reacts like hematite.
GRAYISH WHITE Ilmenite
FeTiO.
Microchem. Negative with all reagents.
Hardness, High. 5-6. Brittle.
Description. C.--Iron-black. Str.—Black to brownish.
B.B. Infusible in O.F., but slightly rounded on edges in hottest R.F.
For wet test for titanium see (IV, 24, b and c).
GRAYISH WHITE Rutile
Microchem. Negative with all reagents.
Hardness, High. 6-6.5.
Internal reflection as seen by inclined light sometimes is reddish.
Description. C.-Reddish brown to nearly black. Str.-Pale brown.
Occurs usually in prismatic crystals. Knee-like twins.
B.B. Infusible. Yields bead and wet tests for titanium (IV, 24).
GRAYISH WHITE Franklinite (FeZn Mn)O.(FeMn)20 (Very Rare)
Microchem. Negative with all reagents.
Hardness, High. 5.5-6.5. Brittle.
Description. C.-Iron-black. Str.---Very dark brown.
B.B. Infusible. With soda gives a green manganate bead and on char-
coal a coating of zinc oxide (IV, 29).
(Note.-Chalcophanite (Mn, Zn)0.2MnO2.2H20, is also grayish white and
behaves chemically like Franklinite.)
WHITE Löllingite See page 91.
TiO2
3
115
GRAY Voltzite ZnSO (Very Rare)
Microchem. Negative with all reagents. (HNO3, fumes sometimes
tarnish very faintly.)
Hardness, Medium. 44.5.
Internal reflection as seen by inclined light is reddish yellow or brown.
Description. C.-Dirty rose-red, yellowish, or brownish. Str.-Light.
Occurs thin curved, lamellar, etc.
B.B. Nearly infusible.' Reduced with soda on charcoal yields white
zinc oxide coat, which when moistened with cobalt nitrate solution and
again heated in the O.F. becomes green (IV, 29, a)
GRAY Erythrovincite* (MnZn)S '', (Very Rare)
Microchem. Negative with all reagents.
Hardness, Medium to low.
Description. C.-Red. Str.-Pale yellow. Occurs in thin plates.
B.B. Yields green manganate bead with soda. Also usual tests for zinc.
!
!
116
HNO3-N
HCI-N
DETERMINATIVE TABLES
KCN-N
Med.
FeCl3-N
YELLOW Chalcopyrite CuFeS2
Microchem. HNO3, Neg.. (Sometimes tarnishes brown; rubs faint.
Fumes also tarnish in such cases.) HCI, Neg. KCN, Neg. (Rarely
tarnishes iridescent with development of scratches.) FeCl, Neg.
HgCl2, Neg... KOH, Neg.
Hardness, Medium. 3.5-4. Brittle.
Description. C.-Brass-yellow. Str.--Greenish.
B.B. On charcoal fuses to a magnetic globule in R. F. Decrepitates in
closed tube and gives sulphur sublimate. Roasted and reduced with
soda, yields copper buttons. Fus.--2.
GALENA WHITE Chalcostibite* CuSbS2 (Very Rare)
Microchem. Negative with all reagents.
Hardness, Medium. 3–4. Brittle.
Description. C.-Blackish gray. Str.-Black. Perfect basal cleavage.
B.B. Yields antimony flame and coat on charcoal. Reduced with soda
gives a globule of metallic copper. Fus.–1.5.
GALENA WHITE Berthierite FeSb2S4
(Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. FeCl3, Neg.
KOH, Slowly tarnishes brownish; rubs faint or clean.
Hardness, Medium to low. 2-3.
Description. C.-Steel-gray.
Str.- Black, Elongated prisms or
fibrous massive.
B.B. Fuses easily, yielding an antimony flame and coat on charcoal, and
a magnetic residue. Fus.-2.
GRAYISH WHITE Baumhauerite Pb4As&S12 (Very Rare)
Microchem. HNO3, Neg. (Sometimes tarnishes along cracks; rubs
clean.) HCI, Neg. KCN, Neg. (Sometimes tarnishes along cracks.)
FeCl, Neg. HgCl2
, Slowly tarnishes brown;, rubs to pale brown.
KOH, Tarnishes iridescent; rubs clean.
Hardness, Medium to low. 3. Brittle.
Internal reflection as seen by inclined light is often red.
Description. C.-Lead-gray. Str.---- Brown. One perfect cleavage.
B.B. Yields arsenic odor and coat on charcoal; lead coat near the assay.
With KI & S flux gives lemon-yellow lead iodide coat (IV, 10, a).
GRAYISH (BROWNISA) WHITE Tetrahedrite CusSb2S,
Microchem. HNO3, Neg. (Fumes sometimes tarnish faint brown; rubs
clean.) HCI, Neg. KCN, Neg. FeCl, Neg. HgCl2, Neg. KOH,
Neg.
Hardness, Medium. 3-4.5. Very brittle.
Description. C.-Gray to black. Str.—Brown to black.
B.B. Reacts for copper, antimony, arsenic, silver, and often mercury,
etc. Almost impossible to distinguish between tetrahedrite and
tennantite. Fus. -1.5.
GRAYISH (GREENISH) WHITE Tennantite CusAs2S7
Like tetrahedrite into which it grades chemically.
PALE YELLOW MILLERITE See page 95.
Pyrrhotite See page 95.
CREAM
Chalmersite See page 95.
CREAMY WHITE PENTLANDITE See page 95.
GRAYISH WHITE BOURNONITE See page 94.
CREAM
117
GRAYISH WHITE Cinnabar HgS
Microchem. Negative with all reagents used.
Hardness, Low. 2-2.5. Slightly sectile. Carmine-red powder when
scratched.
Internal reflection as seen by inclined light is carmine-red.
Description. C.-Cochineal-red, inclining to brownish and lead gray.
Perfect prismatic cleavage.
B.B. On charcoal entirely volatile when pure. In closed tube alone
gives a black sublimate of mercuric sulphide, but with soda, one of
metallic mercury. Fus.—1.5.
GRAYISH WHITE Metacinnabarite Hgs (Very Rare)
Microchem. Negative with all reagents used. (HNO, sometimes
tarnishes faintly.)
Hardness, Low. 3. Slightly brittle.
Description. C.-Grayish black. Str.-Black.
B.B. Like cinnabar.
GRAYISH WHITE Patronite VS.(?) (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KČN, Neg. FeCla, Neg.
HgCl2, Neg. KOH, Tarnishes iridescent; rubs to paler iridescence.
Hardness. Very low. Sectile.
Description. C.-Bluish black. Str.-Bluish gray. Occurs massive
and amorphous.
B.B. Gives test for vanadium with S. Ph. bead. Also wet tests.
GRAY
Lorandite* TIA$S2 (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. FeCl, Neg.
KOH, Quickly develops coating of orange; rubs clean to rough surface.
Hardness, Low. 2-2.5. Dark red powder when scratched.
Internal reflection as seen by inclined light is orange-red.
Description. C.-Carmine-red, often tarnishes gray on the surface.
Str.--Cherry-red. Perfect pinacoidal cleavage yielding flexible lamelle.
B.B. For tests for the rare element thallium see Chapter IV, 21.
GALENA WHITE Freieslebenite See page 98.
GALENA WHITE Berthierite See page 117.
GALENA WHITE Lengenbachite See page 99.
GALENA WHITE Rathite
See page 99.
GRAYISH WHITE Baumhauerite See page 117.
GRAYISH WHITE Molybdenite See page 97.
GRAY
Erythrozincite See page 116.
118
HNO3-N
DETERMINATIVE TABLES
HCI-N
KCN-N
Low
FeCl2-N
1
GALENA WHITE Dufrenoysite Pb2As2S. (Very Rare)
Microchem. HNO3, Neg. HCl, Neg. KCN, Neg. FeCl3, Neg.
HgCl2, Neg. KÖH, Tarnishes iridescent and darkens; rubs to faint
gray, etched surface.
Hardness, Low. 3. Brittle.
Description. C.-Blackish gray. Str.-Reddish brown. Perfect basal
cleavage.
B.B.. On charcoal decrepitates, fuses, and yields a globule of lead which
gives trace of silver on cupellation. Also gives arsenic coat on charcoal.
Fus.-1.
GALENA WHITE Matildite* AgBis, (Very Rare)
Microchem. Negative with all reagents used.
Hardness, Low.
Description. C.-Gray. Str.-Light gray. Often as slender striated
prisms.
B.B. Fuses easily on charcoal, giving a coating of bismuth oxide and on
long heating a globule of silver.
GALENA WAITE Lehrbachite PbSe + HgSe
Microchem. Negative with all reagents used.
Hardness, Low. Quite brittle.
Description. C.-Lead-gray to iron-black. Occurs massive, granular,
etc.
B.B. On charcoal yields to a strong odor of selenium and partly fuses.
In the closed tube
gives a lustrous metallic gray sublimate of mercury
selenide, with sodium carbonate a sublimate consisting of globules of
mercury.
BLUISH WHITE Tiemannite HgSe (Very Rare)
Microchem. Negative with all reagents used.
Hardness, Low. 2.5. Sectile to slightly brittle.
Description. C.--Blackish gray. Str. --Black.
B.B. Decrepitates in the closed tube and when pure entirely sublimes,
giving a black sublimate with the upper edge reddish brown. On char-
coal yields selenium odor and blue flame and deposits a white coat with
a metallic-like luster.
BLUISH WHITE Vrbaite* TIAS2SbS. (Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. FeCl3, Neg.
KOH, Tarnishes iridescent; rubs to gray.
Hardness, Low. Internal reflection by inclined light is red. Yellowish
red powder when scratched.
Description. C.--Gray-black. Str.-Light yellowish red.
BLUISH WHITE Stützite* Ag, Te? (Very Rare)
Microchem. Negative with all reagents used.
Hardness, Low.
Description. C.-Lead-gray with reddish tinge. Str.-Blackish lead-
gray:
B.B. Easily fusible to a dark bead from which a silver globule is obtained
by reduction with soda. Yields tellurium oxide in the open tube.
(IV, 20, c).
GRAYISH WHITE Regnolite Cu,As2S12 (Very Rare)
Microchem. Negative with all reagent used. (HNO3 fumes sometimes
tarnish faint brown; rubs clean.)
Hardness, Low.
Resembles tetrahedrite and tennatite very closely.
GRAYISH WHITE Seligmannite CuPbAsS.
(Very Rare)
Microchem. HNO3, Neg. HCI, Neg. KCN, Neg. FeCl3
, Neg.
HgCl2, Neg. KOH, Slowly tarnishes to iridescence; rubs clean.
Hardness, Low. Sectile to slightly brittle.
Description. C.-Blackish gray. Str.-Brownish black.
B.B. Like bournonite except tests for arsenic instead of antimony.
119
CHAPTER IV
SUPPLEMENTARY TESTS
TABULATED PROPERTIES OF ORE MINERALS
Some few of the opaque minerals when viewed on a polished
surface with vertical illumination show colors other than shades
of white or gray. The following table will often be helpful in
immediately identifying these minerals.
TABLE 7
Color
Purple
Purple
Blue
Yellow
esite Yellow
Pale yellow
Cream
Cream
Cream
Cream
Cream
Cream
Cream
Cream
Cream
Creamy pink
Coppery pink
Coppery pink
Brown
Mineral
Umangite
Rickardite
Covellite
Chalcopyrite
Gold
MILLERITE
(Pyrite)
(Marcasite)
Pyrrhotite
PENTLANDITE
Chalmersite
Whitneyite
Maucherite
Hauchecornite
Sulvanite
Niccolite
Copper
Breithauptite
Bornite
Formula
CuzSez
Cu Tea
Cus
CuFeS2
Au
Nis
FeS2
FeS2
FeS(S)
(FeNi)s
CuFe2S3
Cu,AS
NizAsz
(NiCo)-(Bi,S,Sb)s
Cu3VSA
NiAS
Cu
NiSb
CusFest
Page
77
35
111
117
111
95
57
57
95
95
95
33
55
91
65
55
51
93
53
When the vertical illumination is cut out and the light from
some strong source is allowed to strike the polished surface at
an inclination, a number of the ore minerals reveal more or
less brilliantly colored internal reflections. These colors are
quite characteristic of certain minerals and should always be
observed in the course of an identification. Table 8 lists those
minerals in which such colors are commonly seen.
120
SUPPLEMENTARY TESTS
121
TABLE 8
Formula
Page
Color of internal
Mineral
reflection
Red
Baumhauerite
Red
Cinnabar
Red
Cuprite
Red
Jalpaite
Red
KERMESITE
Red
Livingstonite
Red
Miargyrite
Red
POLYBASITE
Red
Proustite
Red
PYRARGYRITE
Red
(Rutile?)
Red
Vrbaite
Reddish brown
Limonite
Reddish brown
Hübnerite
Brown or yellow (CASSITERITE?)
Brown or yellow Sphalerite
Brown or reddish yellow Vollzite
Brownish or greenish Cuprodescloizite
ALABANDITE
Orange red
Lorandite
Orange
REALGAR
Yellow
(Onofrite?)
Yellow
ORPIMENT
Pb 4AS S 13
HOS
Cu20
3 Ag2S.Cu
Sb2S20
HgSb.S,
AgSbS2
Ag SbS.
AgzAss,
Ag3SbS,
TiO2
TIAS SbS.
2Fe2O3.3H20
MnWO4
SnO2
Zns
Zn SĄ0
(PbZnCu),V,0,.H2O
Mns
TIASS2
Ass
Hg(SSe)
As2S3
117
118
33
67
87
111
110
87
109
111
115
119
114
114
114
94
116
75
41
118
62
111
110
Olive green
When the polished surface of an ore mineral is deeply scratched
or gouged with a sharp needle a powder is usually produced, and
although this is gray or black in the majority of minerals, a few
yield a powder or scratch with distinct colors as seen under the
microscope with vertical illumination. This property may
often be used as a valuable aid in mineral identification. The
minerals giving powders of characteristic colors in this way are
grouped in Table 9 which follows:
122 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
TABLE 9
Page
118
33
Color of powder
Carmen red
Blood red
Blood red
Blood red
Blood red
Red
Red
Red
Red
Reddish brown
Reddish brown
Reddish brown
Pink
Golden brown
Brown to yellow
Orange
Reddish yellow
Yellow
Yellow
Yellow
Yellow
Olive-green
Mineral
Cinnabar
Cuprite
Jalpaite
Proustite
PYRARGYRITE
KERMESITE
Livingstonite
Lorandite
Miargyrite
Hauerite
Hematite
Regnolite
Copper
Bornite
Sphalerite
REALGAR
Cuprodescloizite
CHROMITE
Gold
Limonite
ORPIMENT
ALABANDITE
Formula
Hgs
Cu20
3A82S.CuzS?
AgzAss
Ag3SbS3
Sb2S20
HgSbS 7
TIASS2
AgSbS2
Mn82
Fe2O3
Cu7As2S12
Cu
Cu.FeSA
Zns
Ass
(PbZnCu),V,0,.H2O
FeCr204
Au
2Fe2O3.3H20
As2S3
Mns
67
109
111
87
111
118
110
94
115
119
51
53
94
62
75
114
111
114
110
41
SUPPLEMENTARY TESTS
123
TABLE 10.—CLASSIFICATION ACCORDING TO ELECTRICAL CONDUCTIVITY,
MEASURED WITH Two DRY CELLS WITH VOLTMETER, AND
SHARP's No. 9 SEWING NEEDLES FOR TERMINALS
USING
Electrical conductivity
equal to or greater than
copper, voltmeter reads 150
Average voltmeter readings
Apparently non-conductors,
voltmeter reads 0
Arsenic (native)
Algodonite
Antimony (native)
Bismuth (native)
Calaverite
Chalcopyrrhotite
Chloanthite
Coloradorite
Copper (native)
Covellite
Dyscrasite
Gersdorffite
Glaucodot
Harrisite
Hauchecornite
Hessite
Huntilite
Kallilite
Krennerite
Linnæite
Magnetite
Maucherite
Melonite
Millerite
Mohawkite
Niccolite
Pentlandite
Pyrrhotite
Rammelsbergite
Safflorite
Silver (native)
Skutterudite
Smaltite
Sternbergite
Sylvanite
Tellurium (native)
Ullmannite
Whitneyite
Willyamite
147 Onofrite
145 Löllingite
142 Petzite
142 Bornite
142 Tiemannite
140 Clausthalite
137 Arsenopyrite
137 Eucairite
135 Chalcocite
130 Metacinnabarite
130 Ploydymite
126 Kalgoorlite
126 Altaite
124 Chalcopyrite
120 Galena
120 Stutzite
120 Luzonite
120 Tennantite
120 Aguilarite
109 Steinmannite
85 Berzellianite
80 Naumannite
70 Nagyagite
57 Polytelite
55 Stromeyerite
50 Pearceite
37 Cobaltite
25 Guanajuatite
15 Chivatite
15 Enargite
12 Marcasite
7 Regnolite
7 Lillianite
7 Rezbanyite
7 Pyrite
7 Ilmenite
5 Psilomelane
5 Jamesonite
3 Plenargyrite
3 Chalmersite
3 Famatinite
3 Cosalite
2 Bismuthinite
2 Argentite
2 Stannite
1 Stylotypite
1 Teallite
1 Frankeite
1 Polybasite
I Molybdenite
1 Hematite
Aikinite
Alabandite
Andorite
Argyrodite
Baumhauerite
Boulangerile
Bournonite
Brongniardite
Cassiterite
Chromite
Cinnabar
Cuprite
Cuprodescloisite
Cylindrite
Delafossite
Dufrenoysite
Emplectite
Franklinite
Geocronite
Hauerite
Horsfordite
Jalpaite
Jordanite
Kermesite
Legenbachite
Limonite
Lorandite
Matildite
Meneghinite
Miargyrite
Orpiment
Plagionite
Polyargyrite
Proustite
Pyrargyrite
Rathite
Realgar
Rutile
Seligmannite
Semseyite
Sphalerite
Stephanite
Stibnite
Sulyanite
Tenorite
Tetrahedrite
Uraninite
Voltzite
Wittichenite
Wurtzite
124 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
TABLE 11.-ELECTRO-POTENTIALS OF ORE MINERALS
Potential Less
than 100 per
cent. Cu
Between 5 per
vent. Au-95 per
cent. Cu and 100
per cent. Cu
5 per cent. Au-95 10 per cent. Au - 20 per cent. Au-80) 30 per cent. Au-70
50 per cent. Au-
per cent. Cu to 10 90 per cent. Cu per cent. Cu to 30 per cent. Cu to 40
per cent. Au-90 to 20 per cent. Au
40 per cent. Au-60 per- 50 per cent. Cu
per cent. Au-70
cent. Cu to 50 per cent.
per cent. Au-60
per cent. Cu
-80 per cent. Cu
per cent. Cu
to 60 per cent.
per cent. Cu
Au-50 per cent. Cu
Au-40 percent. Cu
Arsenic
Niccolite
Mohawkite
Domeykite
Pyrrhotite
(Domeykite)
(Pyrite)
Smaltite
Cobaltite
Pyrolusite
Chloanthite
Bornite
Chalcocite
Galena
Tetradymite
Dyscrasite
Magnetite
Marcasite
Nagyagite
Native silver
Stromeyerite
Maucherite
Tennantite
Tellurium
Linnæite
(Magnetite)
Gersdorffite
Hessite
Enargite
(Pyrite)
Famatinite
Löllingite
Luzonite
Lehrbachite
Psilomelane
(Famatinite)
Arsenopyrite
Millerite
Covellite
(Hessite)
Metacinnabarite
Coloradoite
(Enargite)
Pyrite
SUPPLEMENTARY TESTS
125
1
TESTS FOR THE ELEMENTS 9
1. Antimony, Sb
ANTIMONY MINERALS
Minera
Formula
Page
Andorite
Pb AgSb2S
95
Berthierite
FeSb2S4
117
Boulangerite
Pb3Sb2S6
63
BOURNONITE
(Cu2Pb)3Sb2S.
94
Breithauplite
NiSb
93
Brongniardite
Pb Ag2Sb2S.
69
Chalcostibile
CuSbS2
117
Cylindrite
PbSb2Sn S21
77
Dyscrasite
Ag.Sb, etc.
67
Epiboulangerite
PbSb.S.
99
FAMATINITE
CuzSbSA
83
Franckeite
Pb .Sn Sb2S12
79
Freibergite
(CuAg)8Sb2S7
82
Freieslebenite
(Pb, Aga).Sb.Su
98
Geocronite
Pb Sb2S,
79
Guejarite
Cu2Sb S7
83
Hauchecornite
(NiCo),(BiSbS).
91
Horsfordite
Cu Sb
63
JAMESONITE
Pb2Sb2S
62
Kallilite
Ni(Sb Bi)s
57
KERMESITE
Sb2S20
87
Livingstonite
HgSb.S,
111
Meneghinite
Pb4Sb2S7
79
Miargyrite
AgSbS2
110
Nagyagite
Au2Pb10SbTeXS16
98
Plagionite
Pb 6Sb8S17
43
Polyargyrite
Ag2 Sb2S15
109
POLYBASITE
Ag SbS.
87
PYRARGYRITE
Ag3SbS;
111
Rathite
Pb (As, Sb), S
99
Semseyite
Pb7Sb.S16
STEPHANITE
Ag SbS4
101
Stibnite
Sb2S3
87
Styloty pite
3(Cu,Ag Fe)S.Sb2S3
94
Tetrahedrite
CusSb2S7
117
Ullmannite
NiSbs
91
Vrbaite
TIAs2SbS.
119
Willyamite
(CoNi) Sbs
Zinkenite
PbSb2S4
62
9 Reference has been made to standard works on mineralogy and blow-
pipe analysis by A. H. PHILLIPS, Moses and PARSONS, BRUSH and Pen-
FIELD, etc.
45
57
126 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
(a) Coat on Charcoal.-Antimony minerals, when heated on
charcoal in the O.F. yield a white oxide coat which settles fairly
near the assay. This coat is volatile and may be completely
driven off with either flame. The powdered mineral, when
fused with KI & S flux on charcoal, yields a faint yellow coat
(6) Flame Test.—When the above coat is quickly volatilized
in the O.F. the flame is colored a pale yellowish-green. (Arsenic
coat colors the flame faint violet.)
(c) Closed Tube Reaction. Most minerals containing both
antimony and sulphur, when heated in the closed tube, yield a
black sublimate when hot, which becomes reddish-brown upon
cooling.
(d) Open Tube Reaction.—Minerals containing antimony and
sulphur, when heated in the open tube, yield dense white fumes
which settle along the lower half of the tube. This sublimate is
volatile and can be entirely driven off.
2. Arsenic, As
ARSENIC MINERALS
Mineral
Arsenic
Arsenopyrite
Baumhauerite
Chloanthite
Cobaltite
Domeykite
Dufrenoysite
Enargite
GERSDORFFITE
GLAUCODOT
Guitermanite
Jordanite
Lengenbachite
Löliingite
Lorandite
Luzonite
Maucherite
Niccolite
ORPIMENT
Pearcite
Proustite
Rammelsbergite
Rathite
REALGAR
Formula
As
FeAss
Pb,As6S13
NiAs?
CoASS
CuzAs
Pb2As2S
CuzASS4
NiAss
(CoFe) Ass
Pb3As2S.
Pb4As2S7
Pb6(Ag Cu)2A54S13
FeAs2
TIASS2
CuzASSA
NizAs2
NiAs
As2S3
Ag Ass
Ag3AsSg
NiAS2
Pb(AsSb)S
Ass
Page
59
57
117
89
115
35
119
83
89
91
99
99
99
91
118
83
55
55
110
85
109
89
99
62
SUPPLEMENTARY TESTS
127
Mineral
Regnolite
Saffiorite
Seligmannite
Smaltite
Sperrylite
Tennantite
Vrbaite
Whitneyite
Formula
Cu7As2S12
COAS2
CuPbAsS
COAS2
PtAs2
CugAs2S7
TIAs2SbS,
Cu,As
Page
119
55
119
55
115
117
119
33
(a) Coat on Charcoal.--Arsenic minerals, when heated on
charcoal in the O.F. yield a white oxide coat which settles at a
distance from the assay. (Beyond the antimony coat.) This
coat is extremely volatile in either flame and, with the R.F.
especially, strong characteristic garlic-like odors are given off,
(6) Flame Test.—When arsenic minerals are heated on char-
coal in the R.F. the flame is colored a faint violet. (Antimony
yields a pale, yellowish green flame.)
(c) Closed Tube Reaction.-Fusible arsenic minerals mixed
with coal dust are placed in the bottom of a narrow closed tube
and covered with a small splinter of charcoal. First heat the
coal to glowing and then the mineral and coal dust mixture.
Any arsenic present, reduced in passing over the hot carbon,
deposits as a mirror on the cold walls of the tube. The mirror
may be tested by breaking off the bottom of the tube and heat-
ing in the Bunsen flame. The characteristic garlic-like odor
of arsenic can now be detected as the fumes escape from the
mouth of the tube. These fumes also impart a faint violet tinge
to the flame if allowed to escape in it. Most arsenic minerals
when heated in the closed tube without a flux yield a sublimate
which is dark red when hot and reddish-yellow when cold.
(d) Open Tube Reactions.--Arsenic minerals, when very slowly
heated in the open tube, yield a ring of white crystals which are
very volatile and may be completely driven off from the tube
upon heating. No arsenic odor is usually noticed in this test.
128 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
3. Bismuth, Bi
BISMUTH MINERALS
Mineral
Aikinite
Beegerite
Bismuth
Bismuthinite
Chilenite
Chiviatite
Cosalite
Dognacskaite
Emplectite
Guanajuatite
Hauchecornite
Kallilite
Lillianite
Matildite
Rezbanyite
Tapalpaite
Tetradymite
Wittichenite
Formula
Pb CuBisz
Pb Bi2S,
Bi
Bi2S3
Ag.Bi
Pb2Bi2Su
Pb Bi S.
Cu, Bi, and s
CuBiS2
Bi2Sez
(NiCo)(BiSSb)
Ni(Sb Bi)s
Pb3Bi2S6
AgBiS2
Pb Bi10S19
3Ag2(ST).Big(STe),
Biz(Te,S);
CuzBisz
Page
63
98
43
62
35
63
59
63
63
98
91
57
77
119
61
43
61
93
(a) Coat on Charcoal.—Bismuth minerals, finely powdered
and mixed with 2 or 3 parts of sodium carbonate, when heated
in the R.F., yield metallic globules which are brittle instead of
malleable (as in the case of lead). If the heating is continued,
oxide forms and volatilizes, depositing a yellow coat close to
the assay. This coat is very similar to that of lead and is best
distinguished from it by means of the iodide reaction. The
above coat moistened with hydriodic acid and heated gently in
the O.F., or the powdered mineral mixed with 2 or 3 parts of
KI & S flux and similarly heated, yields a brick-red bismuth
iodide coat at some distance from the assay, inside of which
there is often a yellow oxide coat.
4. Chromium, Cr
CHROMITE
FeCr204
Page 114
(a) Bead Tests.-The bead tests for chromium, as for most
other elements are only satisfactory when other substances do
not interfere. The colors of the borax and S.Ph. beads are given
in Table 17, page 149.
(b) Wet Test.-Fuse the finely ground chromium mineral mixed
with 4 parts sodium carbonate and 2 parts of potassium nitrate
SUPPLEMENTARY TESTS
129
on a platinum wire. The fusion is dissolved in 2 or 3 c.c. of
water, acidified with acetic acid, and filtered if the solution is not
clear. If 2 or 3 drops of lead acetate are now added, any chro-
mium present will be precipitated as yellow lead chromate. This
may be filtered off and tested as in (a).
5. Cobalt, Co
COBALT MINERALS
8
Minera
Cobaltite
GLAUCODOT
Hauchecornite
Linncite
Saflorite
Smaltite
Willyamite
Formula
COASS
(CoFe) Ass
(NiCo)(BiSSb)
CozS4
CoAs2
CoAsz
(CoNi)SbS
Page
115
91
91
91
55
55
57
(a) Bead Tests.—Cobalt minerals, when dissolved in S.Ph. or
borax, after roasting on charcoal, yield a deep blue bead in all
flames. This test is quite sensitive, but if very large amounts
of copper or nickel are present the borax bead should be taken
from the wire and reduced beside tin on charcoal. The copper
and nickel are absorbed by the tin and the bead will remain blue.
6. Copper, Cu
Mineral
Aikinite
Berzelianite
Bornite
BOURNONITE
Chalcocite
Chalcopyrite
Chalcostibile
Chalmersite
Copper
Covellite
Crookesite
Cuprite
Cuprodescloizite
Delafossite
Dognacskaite
Domeylcite
Emplectite
Enargite
COPPER MINERALS
Formula
PbCuBisz
Cu Se
CuFeSA
(PbCug) 3Sb2S6
Cu s
CuFeS2
CuSbS2
CuFeS2
Cu
Cus
(CuTiAg)2Se
Cu20
(PbZnCu).V209.H2O
CuO, Fe2O3
Cu, Bi, and S
CuzAS
CuBis2
CuzAss
Page
63
97
53
94
51
117
117
95
51
111
94
33
75
103
63
35
63
83
130 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
Page
97
83
82
83
63
67
Mineral
Eucairite
FAMATINITE
Freibergite
Guejarite
Horsfordite
Jalpaite
Lengenbachite
Luzonite
Regnolite
Rickardite
Seligmannite
Stannite
Stromeyerite
Styloty pite
Sulvanite
Tennantite
TENORITE
Tetrahedrite
Umangite
Whitneyite
Wittichenite
Formula
Cu Se.Ag2Se
CuzSbS4
(CuAg).Sb2S7
Cu2SbAS7
Cu.Sb
Cu2S.3A82S
Pb(Ag Cu),As $18
CuzAsS4
Cu7As2S12
Cu Tez
CuPb ASS:
Sn CugFes,
(Ag, Cu)28
3(Cu,Ag Fe)S.Sb2S
Cu3VS4
CugAs2S7
Cuo
CuSb2S;
CuzSez
CugAS
Cu Bis
99
83
119
35
119
94
67
94
65
117
73
117
77
33
95
(a) Reduction on Charcoal.—Copper minerals, roasted in 0.F.
on charcoal, then finely ground and mixed with two or three
parts of sodium carbonate and borax, when treated in a strong
R.F. on charcoal, yield malleable copper buttons. It may some-
times be necessary to crush and wash the charge in the mortar
to obtain the buttons if small.
(6) Flame Tests.-Copper minerals heated in O.F. on charcoal;
moistened with HCl and then reheated in the R.F., yield a brilliant
azure-blue copper chloride flame, which may be tinged with the
green flame of copper oxide. This azure-blue flame is very sensi-
tive and will detect a fraction of 1 per cent. of copper. Copper
oxide and a few copper minerals when powdered and heated
directly in the O.F. yield an emerald-green flame.
(c) Bead Tests.—Copper minerals, when roasted in 0.F.
charcoal, and dissolved in S.Ph. or borax, yield a green bead while
hot, which becomes blue when cold. In the R.F. if much oxide
is present, the cold bead in reflected light is an opaque red due
to cuprous oxide, Cu20.
(d) Wet Test.—Copper salts color all acid solutions blue or
green. With an excess of ammonium hydroxide the solution
turns deep blue. Iron, if present, may be held in solution by
adding tartaric acid before introducing the ammonia.
on
SUPPLEMENTARY TESTS
131
7. Germanium, Ge
Argyrodito
Ag Ges;
Page 110
(a) Coat on Charcoal.–Argyrodite, when heated in the R.F.
and O.F. on charcoal, yields a glazy white coat near the assay,
which assumes a yellowish color at a distance from it.
8. Gold, Au
GOLD MINERALS
Mineral
CALAVERITE
Gold
Kalgoorlite
KRENNERITE
Nagyagite
Petzite
Sylvanite
Formula
AgAuТe,
Au
Hg AugAg&Tec
AgAu Teg
Au2Pb10Sb Te S16
(AgAu)2Te
AgAuТe,
Page
61
111
97
63
98
97
98
Gold is usually present in such small amounts that ordinary
blowpipe methods are not of much value in detecting it. It is
present as a major constituent only in the tellurides, and reducing
these minerals with sodium carbonate on charcoal in the R.F.
yields a malleable button containing gold and silver. After dis-
solving with nitric acid the black residue is ignited and turns gold
yellow.
9. Iron, Fe
Mineral
Arsenopyrite
Berthierite
Bornite
Chalcopyrite
Chalmersite
CHROMITE
Delafossite
Ferberile
GLAUCODOT
Göthite
Franklinite
Hematite
Ilmenite
Limonite
IRON MINERALS
Formula
FeAss
FeSb2S4
Cu, Fest
CuFeS2
CuFe2S
FeCr,04
CuO, Fe2O3
FeWO
(CoFe) Ass
Fe2O3.H20
(FeZnMn)O.(FeMn)203
Fe2O3
FeTi03
2Fe2O3.3H20
Page
57
117
53
117
95
114
103
114
91
114
115
115
115
114
+
132 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
Mineral
Löllingite
Magnetite
Marcasite
PENTLANDITE
Pyrite
Pyrrhotite
Stannite
Sternbergite
Stylotypite
Turgite
WOLFRAMITE
Formula
FeAs2
Fe304
Fesz
(FeNi)S
Fes,
FeS(S).
Sn CuzFeS
AgFe,S.
3(Cu,Ag,Fe)S.Sb2S3
2Fe203.H20
(FeMn)WOA
Page
91
115
57
95
57
95
94
99
94
114
114
(a) Magnetic Test.-—Iron minerals when treated on charcoal in
the R.F. become magnetic after cooling. Cobalt and Nickel also
become magnetic when so treated and, when their presence is
suspected, may be tested for as on pages 129 and 135.
(6) Bead Tests. The colors obtained upon dissolving iron
minerals after roasting in S.Ph. or borax are not very satisfactory
and should not be depended upon alone for identifications. For
these tests see Table 17, page 149.
(C) Wet Test.--When ammonium hydroxide is added in excess
to a solution obtained by boiling any iron mineral in nitric acid,
a heavy precipitate of reddish-brown ferric hydroxide is thrown
down. In this way iron may be quantitatively separated from
the solution. The precipitate filtered off may be tested in the
S.Ph. or borax bead or it may be ignited on charcoal and tested
for magnetism.
10. Lead, Pb
LEAD MINERALS
Mineral
Aikinite
Allaite
Andorite
Baumhauerite
Beegerite
Boulangerite
BOURNONITE
Brongniardite
Chiviatite
Clausthalite
Cosalite
Cuprodescloizite
Formula
Pb CuBisz
РЬТе
Pb AgSb2S6
Pb4AS&S 13
Pb.Bi2S,
Pb 3Sb2S
(PbCuz) 3Sb2S6
PbAg2Sb2S.
Pb2Bi2S11
Pb Se
Pb Bi2S6
(PbZnCu).V209.H2O
Page
63
43
95
117
98
63
94
69
63
77
59
75
SUPPLEMENTARY TESTS
133
Mineral
Cylindrite
Dufrenoysite
Epiboulangerite
Franckeite
Freieslebenite
Galena
Geocronite
Guitermanite
JAMESONITE
Jordanite
Lehrbachite
Lengenbachite
Lillianite
Meneghinite
Nagyagite
Naumannite
Plagionite
Rathite
Rezbanyite
Seligmannite
Semseyite
Teallite
Uraninite
Zinkenite
Formula
Pb&Sb2Sn6821
Pb As2S5
Pb3Sb2S:
Pb Sn Sb2S12
(Pb Ag2) Sb4S11
Pbs
Pb .Sb2S:
PbzAs2S.
Pb2Sb2S
Pb,As2S7
Pb Se + HgSe
Pb (Ag Cu),As,S13
Pb Bi2S6
PbSb2S7
Au2Pb10Sb Te&S16
(Ag2Pb) Se
Pb 6Sb 8,517
Pb (As, Sb),s
Pb ,Bi10S19
CuPb AsSz
Pb7Sb6S16
PbSnS2
Uranate of U, Pb, Th, etc
PbSb.S.
Page
77
119
99
79
98
77
79
99
62
99
119
99
77
79
98
43
43
99
61
119
45
77
113
62
(a) Coat on Charcoal.—Lead minerals when slowly heated on
charcoal yield a volatile yellow oxide coat which deposits close
to the assay. (If much sulphur is present and the heating is
rapid, a white coat similar to the antimony coat is formed--this
does not occur when the heating is done slowly.) This yellow
coat, moistened with hydriodic acid and heated gently in the
O.F., or the powdered mineral mixed with 2 or 3 parts of KI & S
flux and similarly heated, yields a lemon-yellow lead iodide coat.
(Similarly treated, Bismuth yields a brick-red coat.)
(6) Reduction on Charcoal.—Lead minerals powdered and
roasted in a very small O.F., then mixed with 4 parts sodium
carbonate, 1 part borax, and 1 part charcoal dust, and treated
with the R.F. on charcoal, yield soft, highly malleable metallic
lead buttons. (Bismuth buttons are brittle.)
(c) Wet Test.-Sulphuric acid added to a nitric acid solution of
lead minerals, brings down a white powdery precipitate of lead
sulphate. This, when filtered off, may be tested on charcoal as
in (a) and (6)
134 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
11. Manganese, Mn
MANGANESE MINERALS
Mineral
Formula
Page
ALABANDITE
Mus
41
BRAUNITE
3 Mn203. MnSiO3
114
Erythrozincite
(MnZn)s
116
Franklinite
(FeZnMn) 0.(FeMn)203
115
Hauerite
Masz
94
HAUSMANNITE
MnO.Mn203
114
Hübnerite
MnW04
114
MANGANITE
Mn202.H20
114
PSILOMELANE
H.MnO
71
Pyrolusite
MnO2
101
WOLFRAMITE
(FeMn)WOA
114
(a) Sodium Carbonate and Niter Bead. Any manganese
mineral and any mineral containing as much as 0.1 per cent. of
manganese will give a decisive test with this method, which,
moreover, is not interfered with by the presence of any other
substances. The finely powdered mineral, after roasting on
charcoal, is fused with sodium carbonate on a platinum wire in
the O.F. and again fused with a small grain of potassium nitrate
in the 0.F. The resulting bead will be green to dark blue, de-
pending upon the amount of manganese present.
(6) Common Bead Tests.-Manganese imparts characteristic
colors to the borax bead, and to a lesser extent, to the S.Ph.
bead. See Table 17, page 149, for these colors.
12. Mercury, Hg
Mineral
Cinnabar
Coloradoite
Kalgoorlite
Lehrbachite
Livingstonite
Metacinnabarite
Onofrite
Tiemannile
MERCURY MINERALS
Formula
Hgs
HgTe
HgAugAg&Tec
PbSe + HgSe
HgSbAS7
HOS -
Hg (SS)
HgSe
Page
118
97
97
119
111
118
111
119
(a) Closed Tube Reaction.—Mercury minerals, powdered and
mixed with 3 parts sodium carbonate, placed in a closed tube with
a little sodium carbonate on top of the charge, and heated,
yield a gray sublimate of metallic mercury globules on the walls
of the tube. The common mercury mineral, cinnabar (and
SUPPLEMENTARY TESTS
135
metacinnabarite) when heated alone in the closed tube, yields a
black sublimate on the cold walls of the tube.
(6) Open Tube Reaction.--Mercury minerals, when heated
very slowly in the open tube, yield a gray sublimate of metallic
mercury.
13. Molybdenum, Mo
Molybdenite
MoS2
(a) Coat on Charcoal.-Molybdenite, strongly heated in the
O.F. on charcoal, yields a volatile oxide coat which is yellowish
while hot and white when cold. If this coat is touched in-
stantaneously with the R.F. it turns deep blue. Close about the
assay a non-volatile film of copper-red MoO, may sometimes
be seen.
(6) Bead Tests.-After roasting on charcoal, molybdenite
imparts characteristic colors to the S.Ph. and borax beads.
See Table 17, on page 149.
Page
93
Mineral
Briethauptite
Chloanthite
GERSDORFFITE
Hauchecornite
Kallilite
Maucherite
Melonite
MILLERITE
Niccolite
PENTLANDITE
Polydymite
Rammelsbergite
Ullmannite
Willyamite
14. Nickel, Ni
NICKEL MINERALS
Formula
NiSb
NiAs2
NiASS
(NiCo)-(BiSbS)
Ni(Sb Bi)S
NizAs2
Ni Te
Nis
NiAs
(FeNi)S
Ni,S.
NiAsz
NiSbs
(CoNi)SES
89
89
91
57
55
61
95
55
95
57
89
91
57
(a) Bead Tests.-For the colors imparted by nickel to the borax
and S.Ph. beads see Table 17, page 149. Tron, cobalt, and
copper, etc. will often entirely obscure the nickel color. It
may often be detected in the presence of these elements by the
following procedure: The mineral is fused to a globule and most
of the arsenic, antimony, or sulphur roasted off. A piece of
borax twice the size of the globule is placed beside it on the
charcoal and heated in the O.F. for a short time, and the color
of the bead observed. Iron, cobalt, nickel, and copper oxidize in
136 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
the order named, and if successive charges of borax are each
treated briefly in the O.F. beside the globule, each element will
in turn impart its color to the bead. The amount of each
present may be roughly estimated from the number of fresh
charges of borax required to absorb it. For example, if it
takes two or three beads to remove the cobalt it is present only
as a minor constituent and after the cobalt blue has disappeared,
the borax will be colored reddish brown by any nickel present.
Even with this procedure the results are not always satisfactory,
in which case the following wet reaction must be resorted to.
(6) Wet Test.-The powdered mineral is dissolved in 4 or 5
C.C. of nitric acid, an equal amount of tartaric acid is added, and
ammonium hydroxide to excess. The tartaric acid holds the
iron in solution. The liquid may be filtered if not clear and
then made neutral or very slightly acid with HCl. If 3 or 4
drops of a 1 per cent. solution of dimethyl glyoxime in alcohol
are now added, any nickel present will be thrown down as a
brilliant red precipitate. This precipitate, when filtered off,
may be tested for nickel in the beads as in (a). This test is very
sensitive and is not interfered with by other elements provided
the iron is held in solution by sufficient tartaric acid.
Mineral
CASSITERITE
CHROMITE
Cuprite
Cuprodescloizile
Delafossite
Franklinite
Ferberite
Hematite
Hübnerite
Ilmenite
KERMESITE
Limonite
Magnetite
PSILOMELANE
Pyrolusite
Rutile.
TENORITE
Uranninite
Vollzite
WOLFRAMITE
15. Oxygen, o
OXYGEN MINERALS
Formula
SnO2
FeCr2O4
Cu20
(PbZnCu)4V,0,.H2O
CuO.Fe2O3
(FeZn Mn0.(FeMn)203
FeWO.
Fe2O3
MnW04
FeTiO3
Sb2S20
2Fe203.3120
Fe304
H4Mn05
MnO2
Page
114
114
33
75
103
115
114
115
114
115
87
114
115
71
101
115
73
113
116
114
TiO2
Cuo
Uranate of U, Pb, Th, etc.
Zn5S40
(FeMn) WO4
SUPPLEMENTARY TESTS
137
Oxygen usually cannot be directly tested for in the minerals,
but its presence is inferred from a knowledge of the character and
behavior before the blowpipe of the other constituents.
16. Platinum, Pt
NATIVE PLATINUM Pt
Sperrylite
PUAS2
Platinum is usually recognized from its physical properties
and insolubility in acids. If present it is collected in the re-
duction and cupellation for silver and gold. (See page 139.)
Įf the button so obtained, or the residue after parting with nitric
acid, is dissolved in aqua regia, evaporated nearly to dryness, a
little hydrochloric acid added, and again almost evaporated,
diluted with a little water, and concentrated ammonium chloride
added, a precipitate of yellow ammonium platinic chloride is
thrown down. Platinum tests are usually delicate operations
and the standard references on qualitative analysis should be
consulted
17. Selenium, Se
SELENIUM MINERALS
Mineral
Aguilarite
Berzelianite
Clausthalite
Crookesite
Eucairite
Guanajuatite
Lehrbachile
Naumannite
Onofrite
Tiemannite
Umangite
Formula
Ag2S.Ag2Se
Cu Se
Pb Se
(CuTiAg).Se
CuzSe.Ag2Se
Bi Sez
PbSe + HgSe
(Ag2Pb) Se
Hg(SSE)
HgSe
CuzSez
Page
76
97
77
94
97.
98
119
43
111
119
77
(a) Coat on Charcoal.--Selenium minerals, when heated on
charcoal, yield a white oxide coat with a metallic-like luster,
sometimes reddish at the edges.
(6) Flame Test.-When the above coat is heated in the R.F.
the flame is colored an intense azure-blue and a disagreeable
characteristic odor is given off. This odor has been likened to
that of horse radish, but really must be experienced in order to
be recognized. It is noticed when even very small amounts of
selenium are present.
138 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
(c) Closed Tube Reaction.-Some selenium minerals, when
heated in the closed tube, yield fused brownish red globules of
selenium on the walls of the tube.
(d) Open Tube Reaction.-Selenium minerals, when heated in
the open tube, yield colorless globules of selenous oxide, which
crystallize and whiten when cold. The characteristic azure-blue
color will be obtained if the volatile oxide fumes are allowed to
escape into the Bunsen flame.
18. Silver, Ag
SILVER MINERALS
Mineral
Aguilarite
Andorite
Argentite
Argyrodite
Brongniardite
CALAVERITE
Cerargyrite
Chilenite
Crookesite
Dyscrasite
Eucairite
Freieslebenite
Freibergite
HESSITE
Jalpaite
Kalgoorlite
Lengenbachite
Matildite
Miargyrite
Naumannite
Pearcite
Petzite
Polyargyrite
POLYBASITE
Proustite
PYRARGYRITE
Silver
STEPHANITE
Sternbergite
Stromeyerite
Stützite
Styloty pite
Sylvanite
Formula
Ag2S.Ag2Se
PbAgSb2S
Ag2S
Ag.Ges.
PbAg2Sb2S.
AgAu Tez
Ag Cl
Ag.Bi
(Cu TlAg) Se
Ag6Sb, etc.
Cu2Se.Ag2Se
(Pb Ag2) 5Sb S11
(CuAg).Sb2S;
Ag.Te
3Ag.S.Cugs
HgAu,Ag.Te.
Pb(Ag Cu)As.S13
AgBiS2
AgSbS2
(Ag2Pb) Se
Ag Asso
(AgAu).Te
Ag24Sb2S16
Ag SbSg
Ag3A$S2
AgzSbS;
Ag
Ag SbS4
AgFes:
(Ag Cu)2S
Ag Te
3(Cu,Ag2Fe)S.Sb2S,
AuAgTea
Page
76
95
67
110
69
61
109
35
94
67
97
98
82
66
67
97
99
119
110
43
85
97
109
86
109
111
43
101
99
67
119
94
98
SUPPLEMENTARY TESTS
139
(a) Reduction on Charcoal.-Silver minerals, when powdered
and well roasted in 0.F., then mixed with 3 or 4 parts of sodium
carbonate and fused on charcoal in the R.F., yield metallic silver,
which should be collected as much as possible into one button.
If the button is not bright it should be heated beside borax on
charcoal in the O.F. The base metals are oxidized first and dis-
solve in the borax, leaving a bright, malleable silver button,
which may be further tested by dissolving in nitric acid and pre-
cipitating the silver as white silver chloride by adding hydro-
chloric acid. This silver chloride precipitate, when filtered off
is insoluble in hot water, while a similar lead precipitate is dis-
solved by boiling water. Mercurous mercury also yields a
white chloride precipitate which is blackened by ammonium hy-
droxide, but mercury should not be found in a button treated as
in the above case.
When the suspected silver mineral occurs in very small amount
and cannot be separated, conclusive tests can be applied provid-
ing the microscope reveals no other mineral likely to contain
silver. The powdered sample is mixed with an equal volume
each of pure test lead and borax glass, and fused and reduced
by the R.F. in a deep cavity on charcoal. Manipulate the assay
to collect the lead in a single button. The O.F. is now applied
to oxidize impurities of arsenic, antimony, etc., and continued
until the globule boils freely. It is now allowed to cool and is
freed of slag by hammering into a small cube. A cupel is now
prepared by compacting dry bone ash in a cavity in charcoal
about a centimeter in diameter and one-half centimeter deep.
The agate pestle is conveniently used in this operation and by
finishing up with a twirling motion the cupel will have a hard,
smooth, concave surface. Any loose bone ash is blown off and
the cupel is strongly ignited in the O.F. to drive off all moisture,
The button is now placed on the cupel and fused in the R.F. for a
few moments; then the O.F. is applied and continued without in-
terruption until all the lead is oxidized and absorbed by the bone
ash, the end point being marked by a distinct change in color
and brightening of the button. If very little silver is present
the bead will appear to disappear entirely, but the spot should
always be carefully examined with the lens. The residual button
will contain any silver, gold, or metals of the platinum group
present in the sample. If the bead is treated with a few drops
of nitric acid and hydrochloric acid added to the liquid, any
140 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
silver present will be thrown down as insoluble white silver
chloride.
19. Sulphur, s
Sulphur is present in most metallic ores and tests for the ele-
ment seldom aid determinations in mineragraphic work.
(a) Roasting on Charcoal.-Sulphur in sulphides, heated on
charcoal in the O.F., yields sulphur dioxide fumes which are rec-
ognized by their odor.
(6) Sodium Carbonate Test.-Powdered sulphide, fused with
about 3 parts of sodium carbonate, when placed on a bright
silver coin and moistened with a little water, stain the coin brown
or black. (Since very faint reactions are sometimes due to the
sulphur in the gas used, the fusion may be made in a closed tube
in cases of doubt.)
20. Tellurium, Te
TELLURIUM MINERALS
Mineral
Formula
Page
Altaite
CALAVERITE
Coloradoite
HESSITE
Kalgoorlite
KRENNERITE
Melonite
Nagyagite
Perzite
Rickardite
Stützite
Sylvanite
Tellurium
Tetradymite
Pb Te
AgAu Te,
HgTe
Ag2 Te
HgAugAg&Tec
AgAu Tez
Ni Tez
Au2Pb 10Sb2 Te 6S 16
(AgAu). Te
Cu Tez
Ag Te
AuAg Te,
Te
Bi (Te,S);
43
61
97
66
97
63
61
98
97
35
119
98
61
61
(a) Coat on Charcoal.-Tellurium minerals, when heated on
charcoal in the R.F., yield a white oxide coat resembling the
antimony coat, which also colors the flame pale greenish.
(6) Closed Tube Reaction.—Tellurium minerals, fused in the
closed tube with 3 parts of sodium carbonate and some charcoal
dust, when dissolved in water after cooling, yield a reddish violet
colored solution which gives a gray tellurium precipitate if poured
out and exposed to the air.
SUPPLEMENTARY TESTS
141
(c) Open Tube Reaction.-Tellurium minerals, when heated in
the open tube, yield heavy white oxide fumes which condense
close to the heated portion of the tube. This sublimate is vola-
tilized with difficulty and fuses to yellow globules which become
colorless on cooling.
(d) Sulphuric Acid Test.-Tellurium minerals, powdered and
heated in a test tube with 2 or 3 c.c. of concentrated sulphuric
acid, yield a reddish violet solution which gives a precipitate as
in (6) when cooled and diluted with a little water.
21. Thallium, T1
Mineral
Crookesite
Lorandite
Vrbaite
THALLIUM MINERALS
Formula
(CuTlAg)2Se
TIASS2
TIAs2SbS,
Page
94
118
119
(a) Coat on Charcoal and Flame.—Thallium minerals, when
heated on charcoal in the R.F., yield a white oxide coat and color
the flame bright green. This coat moistened with hydriodic
acid and heated gently in the O.F., or the powdered mineral
mixed with 2 or 3 parts of KI & S flux and similarly heated, yields
a lemon-yellow coat very similar to that of lead. The bright
green flame, however, will serve to distinguish it from lead.
22. Thorium and the Rare Earths
These rare elements which occur in uraninite, columbite, tan-
talite, samarskite, etc., are detected by somewhat complicated
wet methods. For their application reference should be had to
complete works on analytical chemistry.
23. Tin, Sn
TIN MINERALS
Formula
SnO2
Mineral
CASSITERITE
Cylindrite
Franckeite
Stannite
Teallite
Pb Sb2Sn.S21
Pb .Sb2Sn2S12
SnCu Fest
PbSnS2
Page
114
77
79
94
77
(a) Reduction Test and Coat on Charcoal.-Tin minerals, pow-
dered and roasted, then mixed with 4 parts sodium carbonate,
1 part borax, and 1 part charcoal dust, and treated with the R.F.
142 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
on charcoal, yield white malleable metallic tin globules which
give a white insoluble precipitate on heating in a test tube with
nitric acid. (The charge should not be heated long after reduc-
tion as metallic tin is easily volatile.) An oxide coat is usually
formed very near the assay. This coat, which is yellow while
hot and white when coid, is very like the zinc coat, and like it, is
volatilized with difficulty. If the tin coat is moistened with
cobalt nitrate solution and heated in the O.F. it turns blue or
bluish green when cold. (A zinc coat similarly treated is grass
green.)
24. Titanium, Ti
TITANIUM MINERALS
Formula
Mineral
Ilmenite
Rutile
FeTiO:
TiO2
Page
115
115
(a) Bead Tests.The bead reactions for titanium are not very
decisive and are interfered with by other elements. They will
be found in Table 17, page 149.
(6) Wet T'est with Metallic Tin.-A charge containing not less
than 3 per cent. titanium may be treated as follows: The finely
powdered mineral mixed with 6 parts of sodium carbonate and
a little borax is strongly fused on charcoal. The fusion is dis-
solved in 2 or 3 c.c. of concentrated hydrochloric acid, granu-
lated tin added and the solution heated. The liquid takes on a
violet color especially upon standing a few minutes.
(c) Hydrogen peroxide Test.-For charges containing only a
very small amount of titanium the fusion is carried out as
directed in the foregoing paragraph, but is boiled in a test tube
with 2 or 3 c.c. of dilute sulphuric acid. When dissolved, dilute
with about 10 c.c. water and add about 2 c.c. hydrogen peroxide,
which turns the solution yellow to orange depending on the
amount of titanium present.
25. Tungsten, W
TUNGSTEN MINERALS
Page
Mineral
Ferberite
Hübnerite
Tungstenite
WOLFRAMITE
Formula
FeWO4
MnWOA
WS2
(FeMn)WO
114
114
62
114
SUPPLEMENTARY TESTS
143
(a) Bead Tests.-The bead colors for tungsten will be found in
Table 17, page 149.
(b) Wet Test.-Tungstates, dissolved in the S.Ph. bead, then
reduced beside tin on charcoal, powdered, and boiled with 1 or
2 c.c. of dilute hydrochloric acid and a little granulated tin, yield
a characteristic blue solution.
26. Uranium, U
Uraninite
Uranate of U, Pb, Th, etc.
Page 113
(a) Bead Tests.--The colors which uranium gives when dis-
solved in the S.Ph. bead usually serve to identify it. See Table
17, page 149.
(6) Wet Test.—The powdered mineral is fused with sodium
carbonate and dissolved in hydrochloric acid, nearly neutralized
with ammonium hydroxide, a solution of sodium carbonate added
until precipitation is complete, then half as much more. Let
stand and filter. Acidify the filtrate with hydrochloric acid,
boil to expel CO2, and add an excess of ammonium hydroxide.
The precipitate of yellow ammonium urinate may be filtered
off and tested in the S.Ph. bead as in (a).
27. Vanadium, V
VANADIUM MINERALS
Mineral
Cuprodescloizite
Patronite
Sulvanite
Formula
(PbZnCu).V209.H2O
VSA
Cu:VS.
Page
75
118
65
(a) Bead Tests.-Vanadium minerals yield characteristic colors
with the beads, especially S.Ph. See Table 17, page 149.
(6) Wet Test.--The well roasted vanadium mineral is fused
with 4 parts of sodium carbonate and 2 parts of potassium
nitrate, the fusion is powdered and dissolved in boiling water
and the insoluble residue filtered off. The alkali vanadate
formed will be found in the filtrate, which is acidified with acetic
acid and lead acetate added. A light yellow precipitate of lead
vanadate is formed and turns white on standing. (Lead chromate
so formed is of a brighter yellow color.) The precipitate may
be filtered off and tested in the S.Ph. bead as in (a).
144 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
28. Water, H2O
MINERALS YIELDING WATER
Mineral
Cuprodescloizite
Göthite
Limonite
PSILOMELANE
Turgite
Formula
(PbZnCu),V209.1,0
Fe2O3.H20
2Fe2O3.3H20
H_MnO
2Fe2O3.H20
Page
75
114
114
71
114
When a powdered hydrated mineral is heated in the closed
tube, water of crystallization is expelled and condenses upon the
cold walls of the tube.
29. Zinc, Za
ZINC MINERALS
Mineral
Cuprodescloizite
Erythrozincite
Franklinite
Sphalerite
Voltzite
Wurtzite
Formula
(PbZnCu).V,0,.H2O
(Zn Mn)S
(FeZn Mn)O.(FeM)203
Zns
ZnS40
Zns
Page
75
116
115
94
116
94
(a) Coat on Charcoal.--Zinc minerals, when intensely heated
in the R.F. on charcoal, yield a zinc oxide coat which deposits
close to the assay. This coat is pale yellow while hot and white
when cold. It is non-volatile in the O.F. and difficultly volatile
in the R.F. When the powdered zinc mineral is fused with an
equal part of sodium carbonate and a little charcoal dust the
coat is usually heavier and more satisfactory. This coat, if
moistened with cobalt nitrate solution and heated in the O.F.
turns grass-green, at least in spots. (The tin oxide coat similarly
treated is blue or bluish green.)
SUPPLEMENTARY TESTS
145
TABLES OF IMPORTANT CHEMICAL AND BLOWPIPE REACTIONS
TABLE 12.--MICROCHEMICAL REACTIONS 10
10 From W. L. WHITEHEAD's condensation of the complete tables of microchemical tests
on the opaque minerals found in the second volume of " BEHRENS-KLEY Mikrochemische
Analyse," KLEY, P. D. C., 1915, pp. 109-130.
Metal
Reagent
Precipitate
Remarks
Arsenic... Silver nitrate
Lemon yellow
Solution in HCI. Arse-
nic must be as arsenite
Antimony... Cesium chloride
Hexagonal plates
Bismuth.. Cesium chloride
Rhombic plates
Cobalt.. Ammonium mercuric Dark blue prisms
Neutral or slightly acid
sulphocyanate
(acetic) solution
Copper Potassium ferrocyanide Amorphous red brown Acetic acid solution
Gold..
Thallium nitrate
Citron yellow needles Solution must be strong
and neutral
Iron..
Potassium ferrocyanide Dark blue sol. in alk. Much Cu interferes
Lead.
Potassium iodide
Bright yellow hex. Slightly acid (nitric) so-
plates
lution
Manganese. Potassium chromate Yellow brown crystals Solution neutral
Mercury. Potassium iodide
Mercuric-vermilion Reagent added solid
Mercurous-amorphous
bright yellow
Nickel.. Dimethyl glyoxime Acicular magenta col- | In ammoniacal solution
ored
Selenium..... Potassium iodide
Powdery brown red HCI solution of sele-
nates
Silver .. Hydrochloric acid Amorphous white sol- | Nitric acid solution
ukle in
Sulphur Calcium acetate White needles of Casof | Nitric acid solutions of
sulphides give
sul-
phates
Tellurium.... Cesium chloride
Citron yellow octahedra HCl solution of tellu-
rium dioxide
Tin.... Cesium chloride
Colorless cctahedra and Interfering elements
cubes
numerous
Titanium.. Rubidium chloride Hex, and octagonal Reagent added to solu-
plates
tion of sodium Auro-
titanate
Uranium.... Sodium acetate
Tetrahedrons light yel- Weak acetic acid solu-
low
tion
Vanadium... Silver nitrate
Pointed yellow grains Acid solution Pyrovan-
adate
Zinc...
Ammonium mercuric White feathery crystals
sulphocyanate
in crosses and aggre-
gates
TABLE 13.--STANDARD FUSIBILITIES
Fusibility
Standard
Character of fusion
1
2
3
4
Stihnite
Chalcopyrite
Pyrite
(Actinolite)
Large fragments fuse in the yellow flame
Small fragments fuse in the yellow flame
Coarse fragments globular in the O.F.
Coarse edges rounded in the O.F. No opaque
representatives of this class
Needle-like fragments become globular in the
0.F. A few nearly infusible opaque minerals
belong here
5
(Orthoclase)
146 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
TABLE 14.-HEATING ON CHARCOAL
(With or without fluxes)
Sublimate, reduction, etc.
Element
Remarks
near
assay | Zinc
White sublimate at a consider- Arsenic Often yields strong garlic
able distance from the assay.
odor
Very volatile
White sublimate nearer the Antimony
assay than the above. Vola-
tile
White sublimate with metal- Selenium The sublimate touched with
lic-like luster. Very volatile.
the R.F. imparts an azure-
Sometimes reddish at the
blue color to the flame
edges
White sublimate like anti- | Tellurium The sublimate touched with
mony. Volatile
the R.F. volatilizes and
colors the flame green
Sublimate
the
This sublimate moistened
which is pale yellow when
with cobalt nitrate solution
hot, white when cold. Not
and ignited becomes green
volatile in the O.F.
Sublimate which is pale yellow Molybdenum | The sublimate if touched in-
when hot, white when cold.
stantaneously with the R.F.
Copper-red close to the
becomes azure-blue
assay
Sublimate which is faint yel- Tin
The sublimate moistened
low to white when hot, white
with cobalt nitrate solution
when cold. Not volatile in
and ignited becomes bluish-
the O.F.
green
Sublimate which is yellow (Sulphur and This sublimate resembles the
when hot, pale yellow when Lead)
antimony coat and forms
cold. Volatile in the O.F.
when galena or other lead
and R.F.
sulphides are heated very
quickly and intensely
Sublimate close to assay which Lead
This sublimate moistened
is deep yellow when hot, pale
with HI and ignited forms
yellow when cold. Volatile
lemon-yellow lead iodide
in O.F. and R.F.
coat
Sublimate which is deep yel- Bismuth This sublimate moistened
low when hot, pale yellow
with HI and ignited forms a
when cold. Volatile in the
brick-red bismuth iodide
O.F. and R.F.
coat.
Reduction with soda yields Antimony
brittle gray button as well
as coat
SUPPLEMENTARY TESTS
147
TABLE 14.—Continued
Sublimate, reduction, etc.
Element
Remarks
Reduction with soda yields Molybdenum
gray infusible particles as
well as coat
Reduction with soda. yields Tin
malleable white button as
well as coat.
Reduction with soda yields Lead
gray malleable button as well
as coat
Reduction with soda yields Bismuth
reddish white brittle button
as well as coat
Reduction with soda yields Copper,
malleable buttons, but no Silver, or
coat
Gold
Reduction with soda yields Iron, Cobalt,
gray magnetic particles, but or Nickel
no coat
TABLE 15.-SUBLIMATES IN THE CLOSED TUBE
Nature of sublimate
Element
Remarks
Mirror-like; collects in glob- Mercury Mercury minerals fused with
ules.
sodium carbonate
Black; turns red when rubbed. Mercury Cinnabar alone in closed
tube
Mirror-like; does not collect Arsenic and Arsenic minerals fused with
in globules
Tellurium charcoal dust
Deep red when hot; reddish | Arsenic The sulpharsenides heated
yellow when cold
alone in closed tube
Black when hot; reddish | Antimony Some sulphantimonides alone
brown when cold
in closed tube
Red when hot; yellow, cold. Sulphur Many sulphides
White if in small amount
Red to black; becomes red Selenium Selenides
when rubbed.
148 MICROSCOPIC EXAMINATION OF THE ORE MINERALS
TABLE 16.-REACTIONS IN THE OPEN TUBE
Nature of sublimate, etc.
Element
Remarks
All sulphantimonides
Sulpharsenides, etc.
Sulphides containing lead
Dense fumes, depositing white Antimony
powder mostly on under side
of the tube. Pale yellow
while hot, white when cold.
Non-volatile and infusible
White, volatile, and crystal-Arsenic
line sublimate
White, non-volatile sublimate, Tellurium
fusible to colorless or pale
yellow globules
White, non-volatile sublimate, Lead
fusible to yellow globules;
white when cold
White, non-volatile sublimate Bismuth
which is infusible
White, volatile, and crystal- Selenium
line sublimate. Often shows
some red at distance from the
assay
Crystalline sublimate near the Molybdenum
assay; yellow while hot,
white when cold
Volatile metallic mirror of Mercury
gray globules
Sulphides containing bismuth
Globules will unite when
rubbed
SUPPLEMENTARY TESTS
149
TABLE 17.-BEAD REACTIONS WITH BORAX AND SALT OF PHOSPHORUS
Borax
Salt of phosphorus
Element
O.F.
R.F.
O.F.
R.F.
Fine green
Hot, yellow to red; Green
Hot, yellow to Dirty brownish Iron
cold, yellow to
red; cold, yel- or greenish
colorless
low to colorless
Hot, yellow; cold, Brown
Yellowish green Fine green Molybdenum
colorless
to colorless
Hot, pale yellow; Yellow to brown Yellow to color- Hot, dirty blue; Tungsten
cold, colorless
less
cold, fine blue
Hot, pale yellow; Grayish to Pale yellow to | Hot, yellow; Titanium
cold, colorless brown
colorless
cold, violet
Hot, yellow; cold, Colorless Hot, yellow; Colorless
Cerium
pale yellow
cold, colorless
Hot, yellow; cold, Fine green
Fine green
Chromium
yellowish green
Hot, yellow; cold, Fine green Yellow
Vanadium
yellow to colorless
Hot, orange; cold, Green
Greenish yellow
Fine green
Uranium
yellow
Hot, green; cold, Colorless to Green to blue Colorless to Copper
blue
Blue
Blue
Blue
Blue
Cobalt
Hot, violet; cold, Opaque gray
Reddish yellow Reddish yellow Nickel
reddish brown
Hot, violet; cold, Colorless
Violet
Colorless
Manganese
reddish violet
Fine green
opaque red
opaque red
INDEX
Abbreviations, table of, 22
Cerargyrite, 109
Aguilarite, 76
Chalcocite, 51
Aikinite, 63
Chalcophanite, 115
Alabandite, 41
Chalcopyrite, 117
Altaite, 43
Chalcostibite, 117
Alundum, use in grinding and polish- Chalmersite, 95
ing, 2
Chamot, E. M., 11
Andorite, 95
Chilenite, 35
Antimony, native, 96
Chiviatite, 63
tests for the elements, 126 Chloanthite, 89
table of minerals, 125
Chromic oxide, use in polishing, 3
Argentite, 67
Chromite, 114
Argyrodite, 110
Chromium, tests for the element, 128
Arsenic, native, 59
Cinnabar, 118
table of minerals, 126
Clausthalite, 77
tests for the element, 127 Closed tube, sublimates in, 147
Arsenopyrite, 57
Coats on charcoal, table of, 146
Cobalt, tests for the element, 129
Bastin, E. S., 7
table of minerals, 129
Baumhauerite, 117
Cobaltite, 115
Bead colors, table of, 149
Color filters, need for, 13
Beegerite, 98
Berthierite, 117
exposure factors for, 17
Berzelianite, 97
range of transmission, 14
Color of internal reflection of min-
Berzelius, J. J., vii
erals, 121
Bismuth, native, 43
Color of mineral powders, 122
tests for the element, 128
Coloradoite, 97
table of minerals, 128
Colored minerals with vertical illu-
Bismuthinite, 62
mination, 120
Bornite, 53
Conductivity, electrical; method of
Bottles, reagent, 5, 7
testing, 8
Boulangerite, 63
table of mineral conductivity,
Bournonite, 94
123
Braunite, 114
Breithauptite, 93
Copper, native, 51
table of minerals, 129
Brittleness, testing for, 7
tests for the element, 130
Bromyrite, 109
Cosalite, 59
Brongniardite, 69
Covellite, 111
Calaverite, 61
Crookesite, 94
Calf skin, use in polishing, 3
Cuprite, 33
Campbell, William, vii
Cuprodescloizite, 75
Cassiterite, 114
Cylindrite, 77
151
152
INDEX
Delafossite, 103
Germanium, tests for the element,
Determinative tables, 33
131
outline of, 23
Gersdorffite, 89
use of, 20, 21
Glass wheel, use in grinding, 2
Dognacskaite, 63
Glaucodot, 91
Domeykite, 35
Gold, native, 111
Dufrenoysite, 119
table of minerals, 131
Dyscrasite, 67
Göthite, 114
Graton, L. C., x
Electrodes, standard copper and Grinding, methods employed. 2
gold, 10
Guanajuatite, 98
Electrolysis on polished surface, 9 Guejarite, 83
Electro-potential of minerals, table Guitermanite, 99
of, 124
method of testing, 10
Hardness, testing for, 7
Embolite, 109
Hauchecornite, 91
Emplectite, 63
Hauerite, 94
Enargite, 83
Hausmannite, 114
Epiboulangerite, 99
Hematite, 115
Erythrozincite, 116
Hessite, 66
Eucairite, 97
Horsfordite, 63
Exposure, method of determining, Hübnerite, 114
15
Huntilite, 33
factors for color filter, 17
factors for magnification, 17
Illumination, exposure factors for, 16
factors for numerical aperture, Ilmenite, 115
16
Iodobromite, 109
factors for source of light, 16
Iodyrite, 110
graphical solution of, 18
Internal reflection, table of colors,
121
Famatinite, 83
Iron, tests for the element, 132
Ferberite, 114
table of minerals, 131
Ferro-type plate, non-sticking solu-
tion for, 19
Field preparation of polished sec-
Jalpaite, 67
Jamesonite, 62
tion, 4
Jordanite, 99
Filter, color, 13, 14
factors for exposure, 17
Finder, use under miroscope, 5
Kalgoorlite, 97
Focusing for photography, 14
Kallilite, 57
Franckeite, 79
Kermesite, 87
Franklinite, 115
Krennerite, 63
Freibergite, 82
Freieslebenite, 98
Lead, tests for the element, 133
Fusibilies, standard, 145
table of minerals, 132
Lehrbachite, 119
Galena, 77
Lengenbachite, 99
Galenobismutite, 98
Leveling cup, 5, 6
Geocronite, 79
Light, exposure factors for, 16
INDEX
153
scope, 16
Lillianite, 77
Onofrite, 111
Limonite, 114
Open tube, reactions in, 148
Lindgren, Waldemar, x
Orpiment, 110
Linen, use in polishing, 3
Oxygen, table of minerals, 136
Linnaeite, 91
Livingstonite, 111
Patronite, 118
Löllingite, 91
Pearcite, 85
Lorandite, 118
Pentlandite, 95
Luzonite, 83
Petzite, 97
Photomicrography, 12
Magnetite, 115
Plagionite, 43
Magnification curves for Leitz micro- Platinum, tests for the element, 137
Polishing, method employed, 2
exposure factors for, 17
Polyargyrite, 109
Manganese, tests for the element, Polybasite, 87
134
Polydymite, 57
table of minerals, 134
Potential, electrical, method of test-
Manganite, 114
ing, 10
Marcasite, 57
table of electro-potential of
Matildite, 119
minerals, 124
Maucherite, 55
Printing paper, 19
Mees, C. E. Kenneth, 13
Proustite, 109
Melonite, 61
Psilomelane, 71
Meneghinite, 79
Pyrargyrite, 111
Mercury, tests for the element, 134 Pyrite, 57
table of minerals, 134
Pyrolusite, 101
Metacinnabarite, 118
Pyrrhotite, 95
Miargyrite, 110
Microchemical qualitative reactions, Qualitative microchemical tests, 145
145
Microscopes, Sauveur and Boyles- Rammelsbergite, 89
ton, 4, 5
Rare earths, 114
Leitz, 12
Rathite, 99
Millerite, 95
Reactions, features to be observed, 8
Mineragraphy, definition, x
Reagents, method of applying, 7
Molybdenite, 97
table of, 11
Molybdenum, tests for the element, Realgar, 62
135
Reduction on charcoal, 146
Mounting, modelling clay for, 6
Regnolite, 119
Murdoch, Joseph, vii, ix
Rezbanyite, 61
Rickardite, 35
Nagyagite, 98
Rutile, 115
Naumannite, 43
Needle, testing, 7
Safflorite, 55
Niccolite, 55
Sectility, testing for, 7
Nickel, tests for the element, 135 Selenium, tests for the element, 137
table of minerals, 135
table of minerals, 137
Numerical aperture, exposure factors Seligmannite, 119
for, 16
Semseyite, 45
154
INDEX
Tin, tests for the element, 141
table of minerals, 141
Titanium, tests for the element, 142
table of minerals, 142
Tungsten, tests for the element, 143
table of minerals, 142
Tungstenite, 62
Turgite, 114
Silver, native, 43
table of minerals, 138
tests for the element, 139
Smaltite, 55
Sperrylite, 115
Sphalerite, 94
Stannite, 94
Stephanite, 101
Sternbergite, 99
Stibnite, 87
Stromeyerite, 67
Stützite, 119
Stylotypite, 94
Sublimates, in the closed tube, 147
in the open tube, 148
Sulphur, tests for the element, 140
Sulvanite, 65
Sylvanite, 98
Ullmannite, 91
Umangite, 77
Uraninite, 113
Uranium, tests for the element, 143
Vanadium, tests for the element, 143
table of minerals, 143
Voltzite, 116
Vrbaite, 119
Tapalpaite, 43
Teallite, 77
Tellurium, native, 61
table of minerals, 140
tests for the element, 140
Temiskamite, 55
Tennantite, 117
Tenorite, 73
Tetradymite, 61
Tetrahedrite, 117
Thallium, tests for the element, 141
table of minerals, 141
Thorium, tests for the element, 141
Tiemannite, 119
Water, tests for, 144
table of minerals, 144
Whitehead, W. L., x, 1
Whitneyite, 33
Willyamite, 57
Wittichenite, 95
Wolframite, 114
Wratten M plate, 13
Wurtzite, 94
Zinc, tests for the element, 144
table of minerals, 144
Zinkenite, 62
JUL 29 1020
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