.3
COLORADO.
of
COLORADO.
J. S. l
GEORGETOWN, COLO.
GEORGETOWN COURIER PRINT.
1887.
•3
Bancroft Library
INTRODUCTORY.
In the preparation of this glossary, the compiler has depended largely
upon the works of J. D. DANA for a description of the mineral species, except
in cases where the local mineral has undergone examination. He has also
obtained much valuable information from papers upon particular minerals,
read before scientific associations, and from articles prepared for the scientific
press.
From a mineralogical point of view the wealth of Colorado exceeds that of
the other States. In the metallic minerals almost every variety has been
found here. And doubtless many interesting minerals have been overlooked
from causes that it is impossible to guard against. The immense size of the
mineral region, the exceedingly superficial examination, the vast area yet
unexplored, and the absence of scientific knowledge on the part of those whose
discoveries were only prompted by the unusual appearance of minerals, have
led to overlooking many that are of value to the scientist and commerce.
Many minerals given are common to several localities in the State, but,
as observed, non-exploration has prevented a complete knowledge of their
locations. To make subsequent editions of this work more complete, the com-
piler solicits the aid of the reader. Any information regarding localities of
minerals will be greatly appreciated, and where tht variety of a mineral is
in doubt, specimens sent will be investigated.
The compiler is under special obligations to Mr. WHITMAN CROSS and
Mr. W. B. SMITH, of the U. S. Geological Survey, for valuable information.
The following are titles of the works referred to in the following pages :
Proceedings of the Colorado Scientific Society.
Proceedings of the Academy of Natural Science, Philadelphia.
Proceedings of the American Philosophical Society, Philadelphia.
American Journal of Science.
American Chemical Journal.
Bulletins of the U. S. Geological Survey.
J. S. RANDALL.
GEORGETOWN, COLORADO,
January, 1887.
MINERALS OF SOLORADO,
GOLD.
Crystallizes in the Isometric system ; the octahedron and dodecahedron
are the most common forms ; sometimes in cubes and trapezohedrons ;
the crystals are usually small and imperfect, and sometimes elongated ;
also reticulated, arborescent and spongiform shapes, in scales and rolled
masses. Color various shades of gold-yellow, sometimes inclining to sil-
ver-white. Very ductile and malleable. Hardness 2*5 to 3. Specific grav-
ity 19'34 when quite pure.
Occurs in greater or less quantities throughout the moun-
tainous portions, of the State in the gravel of streams and in
veins. The veins of Gilpin County are especially noteworthy
for the amount of gold mined annually. Small but unique
crystals have been found in a number of the mines. Large
masses of wire and leaf gold were taken from the Printer
Boy mine, in Lake County, in 1870. In combination with
tellurium in many of the mines in Boulder County.
SILVER.
Isometric ; occurs crystallized in cubes, octahedrons, trapezohedrons and
other forms, but generally distorted ; usually filiform, arberescent, in
plates or coatings and sometimes massive. Color silver-white, but subject
to tarnish. Ductile. Hardness 2'5-3. Gravity 10'5 when pure.
Found native in small quantities in nearly all silver mines
in the State. In scales, arborescent and filiform, the threads
sometimes knotting a mass two inches in diameter, in the
mines of Georgetown. Occasionally found in nuggets from
the size of a pea to those weighing a pound. The Boulder
Nest mine in Clear Creek County, and the Caribou mine in
Boulder County were especially productive of native silver in
their surface workings. Frequently found in the Blue
Kiver placers. Crystals are very seldom met with.
MERCURY. Quicksilver.
Isometric ; Occurs in small fluid globules. Color tin-white. Lustre me-
tallic.
Has been found sparingly in the tellurium-bearing mines
of Boulder County.
6 Minerals of Colorado.
NATIVE COPPER.
Isometric ; occurs crystallized in numerous and often compound forms ;
often filiform and arborescent ; also massive. Color copper-red. Streak
metallic shining. Ductile and malleable. H. 2'5-3. G. 8'94. Usually
found alloyed with some copper, bismuth, etc.
At the head of Hand-Cart Gulch, where it was mined in
early days under the supposition that it was gold. Occurs in
small quantities in the mines of Central City. Quite large
quantities of wire copper have heen found iu the Pittsburg
mine at Empire. Dendritic coatings found in the Centennial
mine, Georgetown. Loose masses have been found in the
soil near Idaho Springs. Quite abundant in the copper lodes
near Golden, where it occurs in seams from J to one inch in
thickness.
NATIVE BISMUTH.
Hexagonal ; occurs in rhombohedrons nearly approaching the cube ; also
reticulated and arborescent shapes ; foliated and granular. Color silver-
white with a reddish tinge, but subject to tarnish. Cleavable. Sectile.
Brittle when cold, but somewhat malleable when heated. H. 2-2*5. G.
9-72.
Small nuggets of native bismuth are frequently found in
the placers of French Gulch, Summit county. Occasionally
found in the Las Animas mine, Boulder county, associated
with bismutite and bismuthinite. Specimens in collection of
J. S. Randall. Bismuth is used extensively in the arts and
in medicine; with antimony in the construction of the most
sensitive thermometers; with mercury for silvering glass; the
sub-nitrate is used for enameling porcelain, and in gilding;
in the manufacture of porcelain and optical glass ; the nitrate
is used in dyeing lilac and violet in calico printing.
NATIVE TEULURIUM.
Hexagonal; occurs in six-sided prisms with the terminal edges re-
placed by single planes; generally massive and granular. Color tin-
white. Lustre metallic. H. 2-2'5. G. 6'l-6'3. Usually carries some
gold.
Found in the mines of Boulder county, associated with
other tellurium minerals. A few crystals have been found
nearly an inch long. Specimens in compiler's collection.
Tellurium has no use in the arts, and is valuable only for its
gold and silver contents.
NATIVE SULPHUR.
Orthorhombic ; the prevailing form of crystal is an acute octahedron, com-
posed of two four-sided pyramids with rhombic bases; usually occurs in
masses, sometimes consisting of concentric coats. Color sulphur-yellow,
sometimes reddish or brown. Lustre resinous. Transparent to subtrans-
, lucent. H. 1-5-2-5. G. 2;072.
Abundant about the mud volcanoes in the southwestern
part of the State.
Minerals of Colorado. 8
JAROSITE. Sulphate of Iron. G. A. Konig, Proc. Acad. Nat. Sci.,Phila.
Khombehedral ; occurs in crystals ; also massive granular, fibrous, as nod-
ules and as an incrustation. H. 2'5. G. 3'5. Color ochre-yellow, amber-
yellow to dark brown. Lustre resinous to adamantine. Analysis by Konig
of mineral from Iron Arrow mine: sulphuric acid 28'57, sesquioxyd of
iron 51'10, water 10'26, potassa 7'13, and a little soda and silica.
Found in minute brilliant crystals in the Iron Arrow mine,
Chaffee county.
ANGUESIXE. Sulphate of Lead.
Orthorhombic ; occurs in rhombic prisms which assume the general form
of the octahedron when short; often in slender implanted crystals; also
occurs massive; lamellar or granular. Color gray, white, yellowish or
slightly green. Lustre adamantine, inclining to resinous. Transparent to
opaque. H. 3. G. 6. Comp., oxide of lead 73'6, sulphuric acid 26'4.
In the Freeland mine, Clear Creek county, in aggregations
of grayish translucent crystals about the size of a grain of
wheat. In many of the Leadville mines in small crystals and
in crystalline masses. A product of the decomposition of
galena.
ISICCOWTB. Arsenical Nickel.
Hexagonal ; rarely occurs crystallized ; usually massive, sometimes reni-
form with a columnar structure. H. 5-5'5. G. 7'33-7'67. Lustre metallic.
Color pale copper-red, with a gray or black tarnish. Streak pale brown-
ish-black. Comp., arsenic 55*9, nickel 44*1.
Gem mine, on Pine Creek, Fremont county, associated
with bornite and pyritiferous minerals, in dolomite gangue.
Produces annabergite on alteration (Cross). In the mines at
Silver Cliff (G en th). Sparingly in the Rosa mine,atL)umont,
Clear Creek county.
]tlBI*O*?ITK* Tellnride of Nickel. _ W. F. Hillebrand, Proc. Cbl.Sc.Soc.
Hexagonal ; generally occurs in indistinct granular and foliated par-
ticles. Lustre metallic. Color reddish-white, rarely tarnished brown.
Comp., tellurium 76'49, nickel 23'51.
Occurs in the Forlorn Hope mine, Boulder county, in crys-
talline forms, associated with other tellurides. Specimens
in collection of Colorado Scientific Society. A rare mineral,
heretofore found only in California.
PHBNACITB. Silicate of Glucina. W. Cross, Am. Jr. Sc., Oct., 1882.
Rhombohedral ; crystals occasionally oblong, but generally obtuse. Color-
less or bright wine-yellow inclining to red ; lustre vitreous ; transpa-
rent to opaque ; double-refracting. H. 7'5-8. G. 3. Comp., silica 54'2,
glucina 45'8. Resembles quartz.
At Crystal Park, El Paso county, in cavities in granite,
with topaz, zircon, microcline, albite, smoky quartz and li-
monite in large, broken crystals. At Florissant in small, flat
crystals upon amazonstone with albite, gothite and smoky
quartz. Specimens in collection of "Whitman Cross, Denver.
Minerals of Colorado.
Arsenide of Cobalt. W. M. lies, Am. Jr. Sc., May, 1882.
Isometric; occurs in octahedrons, cubes and their modifications; also
massive and in imitative shapes. Color tin-white, inclining to steel-gray
when massive, sometimes iridescent. Lustre metallic. H. 5'5-6. G' 6'4
to 7*2. Analysis of Colorado mineral by lies : cobalt 1T59, iron 11*99,
arsenic 63*82, with traces of lead, bismuth and sulphur.
Abundant in veins near Gothic, Gunnison County, associ-
ated with erythrite, native silver, pyrite and calcite. Pro-
duces erythrite by alteration.
A1,ASKAITE. (new). Sulphide of Bismuth, Lead and Silver. G. A.
Konig, Am. Phil. Soc. Phil., 1881.
Massive, small foliated, with occasional cleavage planes. Color whitish
lead-gray. Lustre metallic. Easily pulverized. G. 6'878. Cornp., sul-
phur 17'63, bismuth 56'97, lead 1179, silver 8.74, copper 3'46, antimony
0'62, zinc 079.
Occurs intimately mixed with quartz, barite, chalcopyrite
and tetrahedrite at the Alaska mine, Poughkeepsie Gulch.
San Juan county. Named after the Alaska mine.
BEBGERITE. (new.) Sulphide of Lead, Copper and Bismuth. G. A. Ko-
nig, Am. Chem. Jr., 1881.
Isometric ; in elongated crystals ; also massive. Cubic cleavage. Color
light te dark gray. Lustre brilliant metallic. Comp., sulphur 14'97, bis-
muth 20*59, lead 64'23, copper 170.
From the Baltic lode, near Grant, Park county. Named
after Mr. Herman Beeger, of Denver.
Arsenical Sulphide of Copper and Iron.
Isometric ; usually occurs in rhombic dodecahedrons, sometimes variously
modified ; also jn cubes and octahedrons, of which the edges and angles
are replaced. Color lead-gray to iron-black. Lustre metallic. H. 3'5-4,
G. 4'37. Comp., varies, copper 48, sulphur 30, arsenic 13, iron 10.
Occurs in the Freeland mine, Clear Creek county, in clus-
ters of splendent crystals from J to J an inch in diameter.
A few dodecahedrons are met with, but most of the crystals
appear complicated. Fine specimens in collection ot com-
piler. This is the first known occurrence of the mineral in
the United States.
Antimonial Sulphide of Lead. W. F. Hillebrand, Proc.
Col. Sci. Soc., vol. 1.
Orthorhombic ; crystals regular six-sided prisms terminated by low six-
sided pyramids; faces of prisms generally deeply striated longitudinally ;
also massive, fibrous and columnar. Resembles stibnite, but is harder and
heavier. Color steel-gray. Lustre metallic. H. 3-3'o. G. 5'30-5.35.
Analysis of Red Mountain mineral by Hillebrand : antimony 35*00, arse-
nic 5'64, lead 3277, copper T22, silver 0'23, sulphur 22'50, and small
amounts of iron, soda, etc.
Occurs massive with apparent crystalline structure, of iron-
gray color, in the Brobdignag mine, Red Mountain, San Juan
county. This is the first observed occurrence of the mineral
in the United States.
Minerals of Colorado. 9
Copper Pyrites. Sulphuret of Copper and Iron.
Tetragonal ; the crystals present the general form of the tetrahedron but
are sometimes compound ; usually occurs massive and frequently amor-
phous. Color brass-yello\r, often with a variegated taruish, Lustre me-
tallic. H. 3-5-4. G. 415. Comp., sulphur 34'9, copper 34*6, iron 30'5.
Massive, in greater or less quantity, in nearly all mines in
the state, and nearly always highly auriferous when found in
gold mines, and argentiferous when found in silver mines.
That from the mines of Red Elephant Mountain, Clear Creek
county, usually carries several hundred ounces of silver in
a ton of ore. Fine tetrahedrons, measuring from J to J an
inch are found in the Freeland mine, Clear Creek county, but
nearly all are incrusted with minute crystals of tennantite.
Fine specimens in collection of J. S. Randall.
BISMUXHIXITE. Bismuth Glance. Sulphide of Bismuth.
Orthorhombic ; occcurs in acicular prisms, striated longitudinally ; also
massive with a foliated or fibrous structure. Color lead-gray inclining to
tin-white, with a yellowish or iridescent tarnish. Lustre metallic. H. 2.
G. 6-4-716. Comp., sulphur 18'75, bismuth 81'25.
In working a quartz vein near Guy Hill, Jefferson county,
a single "pocket" of bismuthinite was encountered, and sev-
eral hundred pounds of the ore taken out. Occurs in stout
columnar aggregations in the Las Animas mine, near Gold
Hill, Boulder county. In quartz veins on Big Thompson
Creek, Larimer county. In small crystals and masses, with
a gold-yellow tarnish, in the Little Giant lode, Clear Creek
county. Beautiful specimens in collection of compiler.
Arsenide of Iron. W. F. Hillebrand, Am. Jr. Sc., May,
1884 ; Proc. Col. Sc. Soc., vol. I.
Orthorhombic; occurs in right rhombic prisms, parallel to whose planes it
may be cleaved ; also massive, acicular and columnar. H. 5-5"5. G. 6*2,
7'43. Color tin-white. Lustre metallic. Analysis of Colorado mineral
by Hillebrand : arsenic 71' 18, iron 22'96, cobalt 4'37, sulphur 0'56, bis-
muth 0'08, copper 0'39, nickel 0'21.
In the mines on Teocalli and White Rock Mountains, in
Gunnison county, in dense radiate masses, and more rarely in
trillings and minute crystals, associated with smaltite, mar-
casite, galena, chalcopyrite, pyrargyrite, argentite, proustite
and native silver, in a gangue of calcite, siderite and barite.
Specimens in collection of Colorado Scientific Society.
(new}. Arsenical Sulphide of Lead. W. F. Hille-
brand, Proc. Col. Sc. Soc., vol. 1.
Occurs massive of a bluish-gray color and slight metallic lustre. H. 3.
G. 5-94. Analysis by Hillebrand : arsenic 13'00, sulphur 19'56, lead 61'63.
copper 0'17, silver 0'02, iron 0'88, oxygen 0'55.
Occurs massive in the Zuni mine, near Silverton, and forms
the matrix of zunyite. Named after Franklin Guiterman,
who first brought the mineral to notice.
10 Minerals of Colorado.
R.HODOCHR.OSIXK. Carbonate ef Manganese.
Rhombohedral ; occurs in saddle-shaped lenticular crystals ; also botry-
oidal and massive. H. 3'5-4'5. G. 3'4-3'7. Listre vitreous inclining to
pearly. Color shades of rose-red, dark red, brown, gray. Translucent.
Structure lamellar. Cornp., carbonic acid 38'6, protoxyd of manganese 61'4.
In beautiful rose-red translucent single crystals in the
Royal Albert and Mountain Monarch veins, Uncompahgre
district, Ouray county. In large opaque clusters in the
Champion vein, Burrough's Park, Hinsdale county (Cross).
In small white radiate bunches upon blue celestite, in the
Garden of the Gods (Hillebrand). Some fine clusters of
crystals have been found in the Danube mine, near Idaho
Springs, Clear Creek county. Specimens in collection of J.
S. Randall.
BR.OCHANTI'TK. Hydrous Sulphate of Copper. Richard Pearce, Proc.
Col, Sc. Soc., vol. 1.
Orthorhombic ; Occurs in well-defined tabular and acicular crystals and
drusy crusts; crystals vertically striated; also massive, and reniform
with a columnar structure. H. 3'5-4. G. 3'78. Color emerald-green to
blackish-green. Lustre vitreous. Transparent, translucent. Comp., sul-
phuric acid 19'9, protoxide of copper 69, water ll'l.
Occurs in considerable quantity and very pure, with par-
tial development of crystal form, in the Monarch mine, Chaf-
fee county.
FLrUORITE* Fluor Spar. Fluorid of Calcium.
Isometric ; occurs in cubes, octahedrons, rhombic dodecahedrons and their
modifications ; crystals often have their faces made up of small cubes, or
cavernous with rectangular cavities ; also massiye, coarse or fine granular.
Easily cleaved into the tetrahedron, acute rhombohedron and octahedron.
H. 4. G. 3'l-3'25. Color white, grey, and various tints of blue, green,
yellow, purple and red. Transparent to opaque. Lustre vitreous, some-
times splendent. Fragments heated or rubbed against each other in the
dark become luminous. Comp., fluorine 48'7, calcium 51'3.
Large veins of quite pure purple fluorite have been found
on St. Vrains Creek and Jim Creek, Boulder county, but are
undeveloped, there being no demand for it at present. On
Bear and Cub Creeks, Jefferson county, associated with ga-
lena. Clusters of transparent crystals, of green color, are
found on Plum Creek, Douglas county. Some very good
crystallized specimens are found in the Crystal Mountains,
El Paso county, associated with amazonstone, gothite, etc.
Massive and crystallized of a deep purple color on Tarryall
Creek, South Park. It also occurs sparingly in many of
the mines throughout the state. Fluor spar is used as a flux
in the reduction of ores, and is the source of hydrofluoric
acid for etching glass. In England it is wrought into vases
and other articles for ornament. Specimens in collection of
J. S. Randall.
Minerals of Colorado. 11
CR.YO WTB. Fluoride of Sodium and Aluminum. Cross and Hittebrand,
Am. Jr. Sc., Oct., 1883.
Orthorhombic ; crystals resemble the cube ; usually occurs massive with a
rectangular cleavage. Color usually snow-white, sometimes brown or
black; lustre vitreous; translucent but becomes more transparent when
immersed in water. Melts in the flame of a candle. H. 2*5. G. 3. Anal-
ysis of Colorado mineral by Plillebrand: Fluorine 53*55, sodium 32*40,
aluminum 12*90, iron oxide, calcium and water.
In small masses in quartz and feldspar veins, with astroph-
yllite, zircon and columbite, near the toll road at St. Peter's
Dome, west of Cheyenne Mountain, El Paso county. Spec-
imens of the cryolite groupe of minerals — cryolite, pachno-
lito, prosopite, thomsenolite and gearksutite — in collection of
Colorado Scientific Society. Specimens of cryolite in collec-
tion of J. S. Randall. Cryolite is used for making soda and
soda and alumina salts, and white glass. Produces pachno-
lite on alteration.
Fluoride of Aluminum, Calcium and Sodium. Cross and
Hillebrand, Am. Jr. Sc., Oct., 1883.
Monoclinic ; crystals usually four-sided prisms ; also occurs massive. Col-
orless to white or yellowish. Transparent to translucent. Analysis by
Hillebrand of Colorado mineral : aluminum 12*36, calcium 18*04, sodium
10*25, water 8*05, fluorine 51*30.
Massive and in small transparent crystals, at St. Peter's
Dome, El Paso county. Product of the alteration of cryo-
lite. Specimens in collection of compiler.
Fluoride of Aluminum and Calcium. Cross and Hillebrand,
Am. Jr. Sc., Oct., 1883.
Moncclinic; occurs in minute imbedded crystals. Colorless, white or
grayish. H. 4*5. G. 2*89. Analysis of Colorado mineral by Hillebrand,
fluorine 35*01, aluminum 23*37, calcium 16*19, magnesium 0*11, sodium
0*33, water 12*41, loss as oxygen 12*58.
At St. Peter's Dome, massive and in small crystals, with
other fluorides.
Fluoride of Aluminum, Calcium and Sodium.
Cross and Hillebrand, Am. Jr, Sc., Oct., 1883.
Monoclinic ; occurs in slender prisms, horizontally striated ; also massive,
opal or chalcedony-like. Color white, sometimes reddish. Lustre vit-
reous to waxy. Transparent to translucent. H. 2*5-4. G. 2*75. Comp.,
fluorine 52*2, aluminum 15*0, calcium 15*4, sodium 7*6, water 9*8.
Found sparingly, mixed with pachnolite, at St. Peter's
Dome.
GBARKSUTIXE. Fluoride of Aluminum, Calcium and Sodium. Cross
and Hillebrand, Am. Jr. Sc., Oct., 1884.
Occurs in minute needles and kaolin-like. Color white. Lustre dull.
H. 2. Analysis of Colorado mineral by Hillebrand : aluminum 15*31,
calcium 22*30, fluorine 42*07, water 15*46, sodium 0*10, potassa 0*04.
Occurs quite abundant as minute crystals and kaolin-like,
at St. Peter's Dome.
12 Minerals of Colorado.
ORTHOCLtASB. Potash Feldspar.
Monoclinic ; occurs in modified oblique rhombic prisms ; usually thick
often rectangular, and also in modified tables ; also massive, some-
times lamellar. Color white, gray and flesh-red common ; also greenish
and bluish, when it is called Amazonstone. Lustre vitreous, sometimes
pearly on a cleavage face. Cleaves easily into plates, Transparent to
subtranslucent. H. 6. G. 2'39-2'62. Corap., silica 64'20, alumina 18'40,
potash 16'95.
The common feldspar of granitic rocks. Fine crystals
are abundant in the Lida the Little Queen lode at Kokomo.
Specimens in collection of J. S. Kandall.
MICR.OCL*INK. Feldspar. Variety Orthoclase.
Color pink and gray. Composition, etc., same as orthoclase.
Associated with amazonstone, etc., near Florissant, and
occurring in the same crystalline forms.
Green Feldspar. Variety Microcline.
Crystallizes in the same system, and has nearly the same composition as
orthoclase. Color bluish-green. According to Konig, the the color is due
to iron.
Fine specimens near Florissant, El Paso county, in cavities
in granite, associated with smoky quartz, albite, topaz, phe-
nacite, fluorite, gothite and columbite. The crystals are often
of great size and frequently in groups. Baveno and Carls-
bad twin crystals are quite frequent. Fine specimens in
the compiler's cabinet.
AI«BrrE. Soda Feldspar.
Triclinic ; occurs generally in flat twin crystals, which are often re-
versed, the one upon the other; also massive, either lamellar or granular,
the laminae sometimes divergent ; granular varieties often quite fine. Color
varies from milk-white to green or red. Lustre pearly upon a cleavage
face. Transparent to opaque. H. 6-7. G. 2'59. Comp., silica 68'6, soda
11-8, alumina 19'6.
Near Florissant with amazonstone, sometimes capping crys-
tals of that mineral, but more frequently forming the base or
matrix in which the crystals are set. Often in granite rocks.
PIXCMSTONE. Volcanic Glass. A fused feldspar.
Occurs massive. Color tints of green, yellow, red, brown and black. Lus-
tre pitch-like or glassy. Translucent to opaque. Breaks with a sharp
edge. H. 5-6. Comp., either orthoclase, albite or oligoclase.
Forms a dyke on the north wall of the Colorado Central
mine, Georgetown. Found near Del Norte.
ZUNYIXE. (new.) Silicate of Alumina. W. F. Hillebrand, Proc. Col. Sci.
Soc., vol. 1.
Isometric; occurs in tetrahedral prisms with similar terminations. Col-
orless when pure, but often black from impurities. Lustre vitreous.
Transparent to opaque. H. 7. G. 2'87. Analysis by Hillebrand : silica
silica 24'33, alumina 57'88, lithia 10'89, fluorine 5'61, chlorine 2'91, with
traces of iron, soda, etc.
Occurs in very small crystals imbedded in guitermanite
from the Zuni mine near Silverton. JSIamed after that mine.
Minerals of Colorado. 13
COSAWTK. Sulphide of Lead and Bismuth. W. F. Hillebrand, Am. Jr.,
Sc., May, 1884; Proc. Col. Sc. Soc., vol. 1.
Crystal apparently rhombic, longitudinally striated. Color lead-gray,
grayish-white, pale yellow on exposed surface. Lustre metallic. H. 3'5.
Analysii ot mineral from Comstock mine, by Hillebrand : bismuth 42'93.
lead 22;49, sulphur 17 '11, silver 8'43, copper 7 '50.
Occurs in irregular masses, rarely an inch in length, with-
out crystalline structure, in the Comstock mine, near Parrott
City, La Plata county, associated with pyrite, sphalerite, a
telluride and gold in a quartz vein. Massive in the Yankee
Girl mine, San Juan county. Specimens in collection of Col-
orado Scientific Society,
AUTUNITE* Lime-Uranite. Phosphate of Uranium and Lime.
Orthorhombic ; crystals very nearly square and cleavable. Color citron-
to sulphur-yellow. Streak yellowish. Translucent. Lustre pearly to ad-
amantine. H. 2-2-5. G. 3-05-3-19. Comp., phosphoric acid 15*7, oxyd
of uranium 62'7, lime 6'17 water 15'5.
Found in the Peabody lode, near Georgetown, in minute
greenish-yellow, tabular crystals. Also in a lode on Chicago
Creek, Clear Creek county. «
Arsenical Sulphide of Copper. B. S. Burton, Am. Jr. Sc.,
Jan., 1868.
Orthorhombic. Massive, granular or columnar. Cleavage perfect giving
a brilliant metallic luster. Color grayish to iron-black. Streak grayish-
black, powder having a metallic luster. Brittle. H. 3. G. 4"43. Anal-
ysis of Willis Gulch mineral by Burton : sulphur 31'56, copper 47'58,
arsenic 17"80, antimony 1"37, iron 1*04.
Occurs massive and crystallized in the Powers lode, Willis
Gulch, Gilpin county. Specimens in the compiler's collection.
ACAXXHI'TE. Silver Glance under an Orthorhombic form.
Orthorhombic ; crystals usually slender-pointed prisms. Luster metallic.
Color iron-black. Sectile, cutting like lead. Fracture uneven, giving
a shining surface. H. 2'5 or under. G. 7'16-7'33. Comp., sulphur 12'9,
silver 87 '1.
Occurs in small crystals in the Little Emma mine, George-
town. Specimens in compiler's collection.
AR.OBKXITE. Silver Glance. Vitreous Silver. Sulphuret of Silver.
Isometric ; primary form the cube ; also occurs in octahedrons and rhom-
bic dodecahedrons; reticulated, dendritic, stalactitic, amorphous and
massive. Color blackish lead-gray. Streak shining. Luster metallic.
Fracture small sub-conchoidal, uneven. Perfectly sectile, cutting like
lead. H. 2-2*5. G. 7'196-7'365. Comp., sulphur 12'9, silver 87;L
This valuable ore of silver occurs in small quantities in
nearly all the silver mines in the state, but is seldom found in
masses weighing more than two or three pounds, although
frequently found in sufficient quantities to make the ore with
which it is associated a high grade silver ore. Very good
crystallized specimens are occasionally met with in the
Georgetown mines. Specimens in compiler's collection.
14 Minerals of Colorado.
BI^ACK. Sulphuret of silver in the form of a powder or stain.
Of frequent occurrence at the surface of silver-bearing
veins. Commonly called "sulphurets."
CHALCEDONY. Cryptocrystalline variety of Quartz.
Occurs in matnmillated, botryoidal and stalactitic forms, but never in a
crystallized state. Luster like that of wax. Color white, grayish, pale-
brown to dark-brown and black, rarely delicate blue. H. 7. G. 2'5-2'8.
Cornp., silica, with some opal silica.
Abundant on the ridge to the left of Willow Creek in Mid-
dle Park ; also in the basalt on Corral Creek. Handsome
pale blue specimens near the Salt Works in South Park; six
miles south of the Salt Works in jasper and semi-opal. Fine
specimens in San Luis Park on La Garita, filling cavities of
amygdaloid. At Los Pinos Agency, in basalt. At the head
of Cherry Creek, pseudomorphous after wood. On the Rio
Grande, 15 miles above Loma, large geodes. Blue specimens
on the Gunnison above the Grand Canon. Common in the
valley of the Gunnison near Grand River. Fine specimens in
the compiler's collection. >
Erubescite. Purple Copper Ore.
Isometric ; the crystals are generally cubes of which the solid angles are
replaced, and the faces are mostly curvilinear. Usually massive. Color
between copper-red and pinchbeck -brown, but it soon acquires an irides-
cent tarnish. Streak pale grayish-black. Luster metallic. Brittle. H.
3. G. 4-4-5-5. Comp., varies, sulphur 22'11, copper 70'13, iron 7'76.
A valuable gold-ore in the gold mines, and in some mines
is quite abundant. Frequently found in silver-bearing veins,
and sometimes becomes a valuable ore of silver. In the com-
piler's collection are some very good crystals from Central.
Cross & Hillebrand, Am. Jr. Sc., June, 1882 ; Bulletin No.
20, U. 8. Geo. Sur.
Rhombohedral ; usually occurs crystallized in obtuse rhombohedrons, and
has a rhombohedral cleavage. Color white and reddish. Luster vitre-
ous. Transparent to translucent. H. 4-5. G. 2'08-2'19. Analysis of
Golden mineral by Hillebrand : silica 47'18, alumina 19'67, potash 0'37,
lime 9-74, strontia 9'43, soda (V51, water 25'15.
Good glassy-white specimens are quite abundant in the
amygdaloid of North Table Mountain, Golden. Specimens
of all the Table Mountain minerals in the compiler's cabinet.
SXIUBITK. Radiated Zeolite. Bulletin No. 20, U. S. Geo. Sur.
Orthorhombic ; usually occurs in prisms of which the edges are replaced,
and with four-sided summits ; often in sheaf-like aggregations and in di-
verging groups ; also massive, in radiating and broad columnar forms.
Color white, sometimes yellow, gray, red or brown. Transparent to trans-
lucent. Luster vitreous. Double refracting. H. 3'5-4. G. 2'094r-2'161.
Analysis of Golden mineral by Hillebrand : silica 54'67, alumina 16*78,
lime 7-98, soda T47, water 19'16.
Occurs sparingly in small, clear crystals in the amygdaloid
of Forth Table Mountain, Golden.
Minerals of Colorado. 15
I^AUMONTIXK. Cross and Hillebrand, Am. Jr. Sc., Aug., 1882, U. £
Geo. Sur., Bui. 20.
Monpclinic ; occurs in columnar, radiating and compact crystalline masses,
and in separate crystals. Color white or yellowish-white, sometimes red-
dish. Luster vitreous to earthy. Transparent to opaque; becoming
opaque and sometimes pulverulent on exposure. H. 3*5-4. G. 2*25-2*36.
Analysis of Table Mountain mineral by Hillebrand : silica 52*07, alumina
21*30, lime H'24, potassa 0*42, soda 0*48, water 14*58.
Occurs as a reddish-yellow sand-like material, and in com-
pact crystalline masses in the cavities of the amygdaloid of
North Table Mountain at Golden.
THOMSONITE. Cross and Hillebrand, Am. Jr. Sc., June, 1882; Bulle-
tin No. 20, U. S. Geo. Sur.
Orlhorhombic ; occurs in right rectangular prisms, with cleavage parallel
to its side ; usually massive with a columnar or radiated structure ; also in
radiated spherical concretions. Luster vitreous inclining to pearly. Color-
less or snow-white ; impure varieties brown. Transparent to translucent.
Pyroelectric. H. 5-5*5. G. 2*3-2*4. Analysis of Golden mineral by Hil-
lebrand : silica 42*66, alumina 29*25. lime 10*90, soda 4*92, water 12*28.
Occurs in the amygdaloid of Table Mountains, Golden, in
minute rectangular blades, which are placed upon each other
like the leaves of a closed fan, and in spherical concretions
having a radiated structure.
ANAI.CITE. Cross and Hillebrand, Am. Jr. Sc., June, 1882 ; Bulletin No.
20, U. S. Geo. Sur.
Isometric ; usually occurs in trapezohedrons, or 24-sided crystals ; also
massive. Luster vitreous. Transparent to opaque. Colorless, white, oc-
casionally grayish, greenish, yellowish or reddish-white. H. 5-5*5. G.
2*22-2*29. Analysis of Gold'en mineral by Hillebrand: silica 55*80,
alumina 22*45, soda 13*45, water 8*35.
Occurs in pure white or transparent crystals, and vary in
size from small ones to those nearly an inch in diameter, in
the amygdaloid of North Table Mountain, Golden. On the
eastern side of the mountain, analcite is specially abundant.
It is also abundant on South Table Mountain, but the crys-
tals are usually quite small.
APOPHYU/TB. Ooss and Hillebrand, Am. Jr. Sc., August, 1882 ; Bul-
letin No. 20, U. S. Geo. Sur.
Tetragonal ; occurs in right square prisms or octahedrons, which often
terminate in a sharp pyrimid ; crystals sometimes nearly cylindrical or
barrel-shaped; also massive and lamellar. Cleavage highly perfect to
all the planes of the primary form. Color white or grayish, sometimes
greenish, yellowish, or reddish. Luster vitreous to pearly. Transparent
to opaque. H. 4*5-5. G. 2*3-2*4. Analysis of Golden mineral by Hille-
brand: silica 51*89, alumina 1*54, iron 0*13, lime 24*51, potash 3*81, soda
0*59, water 16*52, fluorine 1*70.
Occurs in well-developed crystals of prismatic habit in the
amygdaloid of North Table Mountain, Golden. The larger
crystals which are occasionally half an inch in diameter, are
often of a greenish tinge, and have uneven surfaces and are
terminated by a large number of small pyramids.
16 Minerals of Colorado.
A pearly-white, very finely-foliate substance resembling
albin is produced by the alteration of apophyllite, which ac-
cording to Hillebrand, consists of silica 67'96, alumina 8-48,
iron oxyd 1-04, lime 5'47, magnesia 0-53, potassa 1-23, soda
0*74, water 14-55.
Fibrous Zeolite. ~0ross and Hillebrand, Am. Jr. Sc., August,
1882 ; Bulletin No. 20, U.& Qeo. Sur.
Occurs in long slender crystals, often very delicate ; also in silky fibrous or
columnar masses. Luster of crystals vitreous ; of fibrous masses more or
less silky. Colorless or white, grayish or yellowish. Fragile. Transpa-
rent to translucent. H .5. G. 2'2-2'4. Analysis of Golden mineral by Hil-
lebrand : silica 46'17, alumina 26'88, lime 877, soda 6'19, water 12'16.
Occurs in the amygdaloid of North Table Mountain, Gol-
den, in masses composed of exceedingly delicate needles
loosely grouped together, and sometimes as a continuous
membrane, or like a thick cobweb.
NATR.O WTE. Needle Zeolite, Cross and Hillebrand, Bulletin No. 20,
U. S. Geo. Sur.
Orthorhombic ; crystals usually slender, often acicular ; frequently inter-
lacing, divergent, or stellate ; also fibrous, radiating, massive, granular, or
compact. Luster vitreous to pearly. Transparent to translucent. Color
white or colorless, yellowish, grayish or reddish. H. 5-5'5. G. 2'17-2'25.
Analysis of Table Mountain mineral by Hillebrand : silica 43'66, alumina
24-89, lime 4'87, soda 14'66, water 8'09.
Natrolite is the least abundant of the zeolites, and has been
found only on the northern part of South Table Mountain,
where it appears in delicate prisms sparingly deposited upon
analcite or associated with that mineral. It has also been
observed upon yellow calcite, chabazite and thomsonite.
Cross and Hillebrand, Bulletin No. 20, U. S. Geo. Sur.
Rhombohedral ; occurs in twin crystals, the faces of which are often stri-
ated ; frequently in druses. Colorless, white, grayish, greenish, reddish,
yellowish. Luster vitreous. Transparent to translucent. H. 4-4'5. G.
2'09-2'16. Analysis of Golden mineral by Hillebrand : silica 4676,
alumina 21'91, lime H'12, potassa 0'21, soda 1'34, water 18M35.
Small white and colorless crystals occur sparingly in the
amygdaloid of North Table Mountain, Golden. Associated
with the levynite is a fibrous mineral, dull white in color and
never showing crystal faces, which is almost identical with
the levynite in composition.
Fibrous Zeolite. Cross and Hillebrand, Bulletin No. 20, U.
8. Geo. Sur.
Monoclinic; occurs in long or short prismatic or acicular crystals ; very
often in twins ; also massive with a fibrous or radiating structure. Color-
less, snow-white, grayish yellowish, and reddish. Transparent to translu-
cent. Luster vitreous, or silky when fibrous. H. 5-5'5. G. 2'16-2'40.
Analysis of Golden mineral by Hillebrand: silica 46'03, alumina 25*28,
iron oxyd 0'27, lime 1277, soda 1'07, potassa 0'13, water 14'48.
Occurs sparingly in small cavities in a zone just above that
Minerals of Colorado. 17
containing a great number of zeolites on North Table Moun-
tain, Golden. It appears in small spheres or segments of
spheres with a radiate structure, and resembles thomsonite,
though easily distinguished by the brilliant white color and
satin-like luster.
Variety of Halloysite. Hydrous Silicate of Alumina. Cross and
Hillebrand, Bulletin No. 20, U. S. Geo. Sur.
Occurs massive ; clay-like or earthy. Luster somewhat pearly or waxy.
Feels greasy. Colors usually dark. H. 1-2. G. l'8-2'4. Analysis of
Golden mineral by Hillebrand : silica 4617, alumina 22'03, iron oxyd
4'64, lime 2'30, magnesia 2'42, potassa and soda 2'06, water 2O38.
Occurs in the amygdaloid about the center of South Table
Mountain, Golden, as a dark brown clay. Placed in water it
falls apart without decrepitation, unlike ordinary bole. The
mineral is used as a pigment.
HUBNER.IXK. Tungstate of Manganese. Cross and Hillebrand, Bulletin
No. 20, U. S. Geo. Sur.; Proc. Col. Sc. Soc., vol. 1.
Orthorhombic; usually occurs in columnar masses or foliated. Luster ad-
amantine on face of cleayage; elsewhere greasy. Color brownish- red,
brownish-black, yellowish. Streak yellowish-brown. Opaque. H. 4'5.
G. 7'4. Analysis ot mineral from Koyal Albert vein by Hillebrand : silica
0'62, tungstic acid 75'58, protoxyd of manganese 23'40, protoxyd of iron
0-24, lime 0'13, columbic acid (?) 0'05.
The mineral occurs in the Royal Albert vein, Uncompahgre
district, Ouray county, in long flattened crystals vertically
striated, of a brownish-black to pale yellow color, imbedded
in quartz. It is also found near Silverton, and at Jimtown,
Boulder county, where it appears in small blades disseminated
through quartz. Specimens in compiler's cabinet.
HEX1OXROPB. Bloodstone. Cryptocrystalline Quartz.
A bright to leek-green variety of chalcedony or jasper, with small spots of
red jasper looking like drops of blood.
Occurs in a vein of jasper in the hill at the junction of Wil-
low Creek and the Grand River, Middle Park. On account
of its beautiful color, heliotrope has always been much used
for rings, seals and other ornaments. Specimens of the diff-
ferent forms of quartz in the compiler's cabinet.
Cryptocrystalline Quartz.
A variety of chalcedony (p. 14) of a clear bright red tint, pale to deep in
shade. The brownish-red is also called carnelian. The color is due to the
presence of iron.
Found sparingly on the ridge to the left of "Willow Creek
in Middle Park; on the Rio Grande near Loma; near Lark-
spur; on Cherry, Kiowa and Running Creeks, pseudomorph-
ous after wood. From the high polish of which it is suscept-
ible, and its bright colors, carnelian has always, in both an-
cient and modern times, been much used for ornaments.
18 Minerals of Colorado.
PRASE* Cryptocrystalline Quartz.
A translucent leek-green chalcedony (p. 14).
Occasionally found in San Luis Park.
CHRYSOPRASE. Cryptocrystalline Quartz.
An apple-green chalcedony (p. 14), the color of which is due to the pres-
ence of nickel.
Occurs sparingly on La Garita, west of San Luis Park. In
geodes in Middle Park.
BAIMDED AGATE. Fortification Agate. Eye Agate. Clouded Agate.
A variegated chalcedony. The colors are either banded or in clouds. The
bands are delicate parallel lines of various shades of color. They follow
waving or zigzag courses, and are occasionally concentric circular, when it
it is called eye agate. When the colors are irregular it is called clouded
agate.
Banded and clouded agates are occasionally found on Wil-
low Creek in Middle Park ; near the Salt Works in South
Park; near the source of Cherry Creek ; ten miles south of
Canon City, in sandstone; on the La Garita, south of San
Luis Park; large geodes on the Rio Grande, 15 miles above
Loma. Owing to its beauty, variety, hardness and capability
of receiving a high polish, agate is much used both in articles
of utility and ornament.
MOSS AGATE. Mocha Stone.
A chalcedony filled with brown, black, green or red moss-like or dendritic
forms.
Abundant on Williams Fork, Middle Park; in South Park
between Fairplay and the Salt Works.
AGATIZEO WOOD.
Wood petrified with clouded agate.
Middle Park near Hot Spring, and on the right of Willow
Creek; around the Salt Works in South Park; abundant
near the sources of Cherry, Kiowa and Bijou Creeks.
OXYX.
Like agate in consisting of layers, but the layers are in even planes and
usually thicker. The colors are generally of a light brown and an opaque
white.
Occurs sparingly on the ridge to the left of Willow Creek,
in Middle Park, and also near Grand Lake; on the La Garita,
west of San Luis Park; a variety called chalcedonyx is found
in San Luis Park. Eextensively used for cameos and other
articles of adornment.
SARDOXYX.
Those varieties of onyx which are composed of alternate layers of red and
white.
A few specimens have been found in the Willow Creek
region, Middle Park. It is the most beautiful, the rarest and
most valuable form of onyx.
Minerals of Colorado. 19
PYRARGYIMXB. Kuby Silver. Dark Bed Silver Ore.
Rhombohedral ; crystals usually prismatic ; generally occurs in small
masses. Lustre metallic-adamantine. Color black, approaching coch-
ineal-red. Streak cochineal-red. Translucent-opaque. H. 2-2*5. G. 5'7,
Comp., sulphur 177, antimony 22'5, silver 59'8.
Occurs in small masses in most of the silver mines in the
state, but rarely found crystallized. Specimens in compiler's
collection.
PR.OUST1XB. Light Kuby Silver Ore.
Rhombohedral ; occurs in granular masses and in small crystals. Lustre
adamantine. Color cochineal-red. Streak cochineal-red, sometimes in-
clined to aurora-red. Subtransparent — subtranslucent. H. 2.-2'5. G.
5'42-5'56. Comp., sulphur 19'4, arsenic 15'2, silver 65'4.
Occurs in the mines of Geneva District and about Monte-
zuma in small masses and in clusters of minute crystals. In
the Colorado Central mine, Georgetown, in beautiful crystals
and massive, associated with galena, sphalerite and crystals
of polybasite. Compiler's collection.
Indigo Copper Ore.
Hexagonal, but rarely occurs in crystals ; commonly massive or spheroidal.
Color indigo-blue or darker. Streak lead-gray to black, shining. Lustre
of crystals submetallic ; dull when massive. H. l'5-2. G. 4'59. Comp.,
sulphur 33'5, copper 66'5.
Occurs in small grains in the Pewabic lode, Central City.
In the form of a powder in some of the mines of Cascade and
Daily Districts, Clear Creek County.
COI^UMBIXB. Columbate of Iron. Ore of Columbium. J. L. Smith,
Am. Jour. Sc., May, 1877.
Orthorhombic ; occurs in single crystals, crystalline masses, rarely massive.
Lustre submetallic; a little shining. Color iron-black, brownish-black,
grayish-black ; often iridescent. Streak dark red to black. Fracture sub-
conchoidal, uneven. H. 6. G. 5 4-6'5. Analysis, Colorado mineral, by
J. L. Smith : columbic acid 79'61, iron protoxide 14*14, manganese pro-
toxide 4'61, loss by heat '50.
In the Pike's Peak region, in small black acicular crystals
imbedded in amazonstone. A few large single crystals and
fragments have been also been found. Compiler's collection.
Cross and HUlebrand, Bui. No. 20, U. S. Geo. Sur.
Isometric; in cubes and octahedrons. Colorless. Transparent. H. 4*5.
G. 2'4. Comp., alumina 22'94, fluorine 5O05, calcium T99, magnesia 5'52,
sodium 4'66, water 14'84,
Occurs in minute crystals in cavities in thomsenolite and
pachnolite, at St, Peter's Dome, El Paso County. The crys-
tals here found are transparent cubes whose corners are' re-
placed by small octahedron faces and seldom reach a diam-
eter of 1MM. Some crystals of pachnolite seem to be coated by
a crystalline dust whose particles are found under the micro-
scope to be most perfect little crystals of ralstonite.
20 Minerals of Colorado.
BIvP ASOMTBi i (new.) Cross awd Hillebrand, Bui No. 20, Z7. & Geo. SJw*
n ^lm. Jr. Sc., October, 1883.
Probably , isometric ; crystals faces cube and octahedron. Colorless, but
not perfectly clear. Calculated analysis by Hillebrand: alumina 11'32,
calcium 0'72, magnesia G'22^ potassium 28'94, sodium 9'90, fluorine 46'98.
Sparingly as a compact irregular mass iu cavities in mass-
ive pachnolite from St, Peter's Dome, El Paso County, from
which it was named.
ZIRCON. Ooss and Hillebrand, Am. J. Sc., Oct., 1882 ; Konig, Am. Phi. Soc.
xvi, 518, 1877.
Tetragonal ; primary form an obtuse octahedron with a square base ; also
occurs in irregular forms and grains. Lustre adamantine. Colorless, pale
yellowish, grayish, yellowish-green, brownish-yellow, reddish-brown.
Transparent to ; opaque. Fracture conchoidal and brilliant. Double re-
fraction strong, positive. H. 7;5. G. 4'5-4'75. Comp., silica 33, zirconia
67. Konig made an analysis of zircon from the Pike's Peak region, which
was published in the Proceedings of the American Philosophical Society
of Philadelphia, in, 1.877.
Found in numerous localities in the Pike's Peak region,
associated with astrophyllite, amazon stone, etc. Near the
Pike's Peak toll-road, about due west from Cheyenne Moun-
tain, a prospect tunnel, in following a vein-like mass of white
quartz in granite, disclosed zircon imbedded in the quartz so
abundant that a cubic inch of the latter mineral contains from
25 to 100 crystals and particles' of zircon, varying in size from
I™ downward. Some of these crystals are very perfect, but
exhibit only the pyramid, the prisim entirely lacking. Many
of them are beautifully clear and of deep reddish-brown, pink,
pale honey-yellow and occasionally deep emerald-green color.
The perfection of these crystals, with their transparency and
color, make them among the most beautiful known. Small
irregularly shaped zircons and occacionally elongated crystals
occur in the sands of Bear Kiver. They are of various shades
of brown, red and yellow, and many are colorless. Most of
them are transparent and qujte brilliant, but too small to be
cut for setting. Specimens from both the above localities in
the compiler's cabinet. Although the zircon is but rarely
used in jewelry, it makes a beautiful gem when of good color
and has a peculiar opalescent reflection.
Magnesia Alum. Goldsmith, Proc. Acad. Nat. Sci.
1876.
In fine acicular crystals ; long fibrous masses ; and efflorescences. Lustre
silky. Color white or yellowish. Becomes pulverulent and white on ex-
posure. Taste hitter — astringent. H. 1. Analysis of Monument Park
mineral by Goldsmith : sulphuric acid 38'69, alumina 1T90, magnesia 4'89,
potassa-and soda 0'68, sand 1'90, water, by difference, 41'94.
Occurs crystallized in thin needles in the region of Monu-
ment Park.
Minerals of Colorado. 21
AI^TAITE. Telluride of Lead. Genth, Am. Phi. Soc., 1874.
Isometric; usu?lly massive; rarely in cubes. Cleavage cubic.- Lustre
metallic. Color tin-white, resembling that of native antimony, with a yel-
low tarnish, Sectile. H. 3-3'5. G. 8'159. Analysis by Genth of mineral
from the Red Cloud mine, Boulder county: quartz 0'19, gold O'l 9, silver
0'62, copper 0'06, lead 60'22, zinc 9'15, iron 0'48, tellurium 37'99.
Occurs in a number of the tellurium-bearing mines at Gold
Hill, Boulder County. Fine crystals in the Slide mine.
CASSITERTXE. Tin-Stone. Oxyd of Tin. Cross and Hillebrand, Bui.
20, U. S. Geo. Sur.
Tetragonal ; primary form an obtuse pyramid with a square base ; it is
found in quadrangular prisms, terminated by four-sided pyramids, and in
many more complex forms; often in reniform shapes. Structure fibrous
divergent ; also massive, granular or impalpable. Lustre adamantine, and
crystals usually splendent. Color brown or black ; sometimes red, gray,
white or yellow. Streak white, grayish, brownish. Nearly transparent to
opaque. H. 6-7, G. 6'4-7'l. Comp., tin 78-67, oxygen 21'33.
Occurs in small crystalline masses imbedded in albite and
quartz on Devil's Head Mountain, Douglas County, associated
with topaz, amazonstone, smoky quartz and fluor spar.
With amazonstone at Florissant.
Cerium-Epidote. Iddings and Cross, Am. Jr. Sc., Aug., 1885.
Monoclinic ; isomorphous with epidote ; crystals either short, flat tabular,
or long and slender, sometimes acicular ; twins like those of epidote ; also
massive and in angular and rounded grains. Lustre submetallic, pitchy
or resinous — occasionally vitreous. Color pitch-brown to black, either
brownish, greenish, grayish or yellowish. Streak gray, sometimes slightly
greenish or brownish. Subtranslucent to opaque. Fracture uneven or
subconchoidal. Double refraction either distinct or wanting. H. 5'5-6.
G. 3'9-4'2. Comp., silica 33, alumina 15, protoxide of iron 15, cerium 21,
lime 11, lanthanium, didymium, yttria, manganese, etc.
Forms an accessory constituent of the biotite porphyrite of
Ten-Mile District, Summit County, in which the crystals oc-
cur of a brilliant black color and oily lustre. In the porphy-
rite of Mount Silverheels, Park County, of a chestnut-brown
color. In the gneiss of the Medicine Bow Range, the quartz
porphyry of the Mosquito Range, and on Eagle River.
Hydrous Silicate of Alumina. Konig, Proc. Acad. Nat.
Sci. Phila., 1876.
Amorphous; usually in thin incrustations, with mammillary surface;
sometimes stalactitic; occasionally almost pulverulent. Lustre vitreous
to subresinous ; bright and waxy internally. Color pale sky-blue, some-
times greenish to deep green, brown, yellow or colorless. Streak uncol-
ored. Translucent. Fracture imperfectly conchoidal and shining to
earthy. Very brittle. Adheres to the tongue. H. 3. G. 1*85. Comp.,
silica 22, alumina 33, water 41. An analysis by Genth of what was sup-
posed to be chrysocolla, from Bergen Park, gave 33.85 alumina, and 5'40
of copper oxide, which corresponds to allophane and chrysocolla in the
ratio of 5:1.
Forms a thin bluish crust on limonite near Bergen ranch,
Jefferson County.
22 Minerals of Colorado.
Soda Hornblende. Konig, Am. Phi. Soc., 1877.
Probably ruonoclinic; occurs in crystals and cleavable masses. Color
pure black; in thin scales deep green to brown. Streak grayish-green.
H. 6. G. 3'44. Comp., silica 50'5, sesquioxyd of iron 26'9, protoxyd of
iron 12'1, soda 10'5. Analysis of El Paso County mineral by Konig was
published in the proceedings of the American Philosophical Society of
Philadelphia.
Occurs at St. Peter's Dome, El Paso County, with astroph-
yllite, zircon, etc.
GAHXITB. Zinc-Spinel. Oenth, Am. Phi. Soc.
Isometric; occurs in octahedrons and dodecahedrons. Lustre vitreous or
somewhat greasy. Color dark green. grayish -green, deep leek-green, green-
ish-black, bluish, black, yellowish, grayish-brown. Subtranslucent to
opaque. H. 7'5-8. G. 4-4-6. Comp., alumina 61'3, oxyd of zinc 38*7.
Large rough crystals occur in the Cotopaxi mine, Chaftee
County.
TOPAZ. Cross and Hittebrand, Am. Jr. Sc., Oct., 1882; Bui. 20, U. 8. Geo.
Sur. W. B. Smith, Bui. U. S. Geo. Sur.
Orthorhombic ; primary form right rhombic prism; crystals usually hemi-
hedral, the extremes being unlike. Cleavage perfect at right angles to the
principal axis ; also occurs fine columnar, granular, coarse or fine. Lustre
vitreous. Color straw-yellow, wine-yellow, white, grayish, greenish, blu-
ish, reddish. Transparent to subtranslucent. Pyroelectric. H. 8. G.
3*4-3*65. Analysis of Florissant specimen by Hillebrand : silica 33'15,
alumina 57'01, fluorine 16'04, oxygen for fluorine 6*75.
Found in Crystal Park, south of Manitou, in cavities in
granite containing feldspars, smoky quartz, zircon and phena-
cite; at the main amazonstone locality near Florissant : and,
more plentifully and in better form than elsewhere, on Devil's
Head Mountain, Douglas County. In small crystals in the
nevadite from Chalk Mountain, where Lake, Eagle and Sum-
mit Counties join. A fragment of a crystal 3J in. in its long-
est diameter, was found near Florissant, which evidently
came from a crystal about one foot in diameter. It is clear
in parts and has a decided greenish tinge. It was supposed
to be fluor spar by the original collectors, and the other pieces
of the crystal are undoubtedly lost. Crystals are also found
in this locality deposited upon or partially imbedded in am-
azonstone, albite, etc. In size the crystals vary from a length
of nearly two inches to those which are almost microscopic.
Some of the crystals have a decided greenish tinge, although
many are colorless. The topaz found at Devil's Head Moun-
tain also occur in cavities with amazonstone, smoky quartz,
and other minerals, and are the most noteworthy crystallized
species, some of the specimens found being probably the best
yet discovered in the United States. Much of the topaz is
reddish, though wine-yellow, milk-blue, and colorless crystals
are found. Quite perfect and clear crystals have been found
weighing from five to six ounces.
Minerals of Colorado. 23
KAL,IN1TK. Potash Alum. Native Alum.
Isometric ; usually fibrous or massive, or in inealy or solid crusts. Lustre
vitreous. Color white. Transparent — translucent. H. 2-2'5. G. 1'75.
Comp., sulphate of potash 18*4, sulphate of alumina 36'2, water 45'5
Occurs as an efflorescence on argellaceous rocks at Canon
City, on Turkey Creek, Little Thompson Creek, and in small
quantities in various localities along the "hog-back. "
STIBNITE. Antimony Glance. Sulphuret of Antimony.
Orthorhombic ; primary form a right rhombic prism ; occurs crystallized
in variously modified and terminated rhombic prisms, which are some-
times closely aggregated laterally ; lateral planes of crystals deeply stri-
ated longitudinally ; also occurs columnar, coarse or fine; also granular to
impalpable. Color and streak lead-gray ; inclining to steel-gray; subject
to blackish tarnish. Lustre metallic. Sectile. Thin lamina a little flex-
ible. H. 2. G. 4-51-4-62. Comp., sulphur 28*2, antimony 71'8.
Occurs crystallized in the North Star mine, Sultan Moun-
tain, near Silverton.
QUARTZ.
Rhombohedral ; occurs in hexagonal prisms, sometimes terminated at both
ends by six-sided pyramids. Colorless when pure ; various shades of yel-
low, red, brown, green, blue, violet and black. Transparent to opaque.
Lustre vitreous, sometimes inclining to resinous. Fracture conchoidal.
Tough, brittle, friable. H. 7. G. 2'5-2"8. Comp., pure silica, or, oxygen
53-33, silicon 46 '67.
Quartz is a constituent of many rocks, and composes most
of the pebbles of gravel beds. It takes on more forms and
colors than any other mineral, and is divided into three va-
rieties, the vitreous, chalcedonic and jaspery. Vitreous vari-
eties are distinguished by their glassy fracture ; chalcedonic
varieties by having a subvitreous or waxy lustre, and gener-
ally translucent ; the jaspery varieties are opaque.
ROCK CRYSTAL.
Pure pellucid quartz. Usually occurs in six-sided crystals.
Clear crystals, some of which are doubly terminated, are
found near Maysville. Large crystals in the Blk mountains.
Pellucid water- worn nodules in the gravel of Platte River.
Common as drusy incrustations in the mines. Rock crystal
is made into lenses for spectacles, and is known as Scotch and
Brazilian Pebbles. The so-called Alaska and California dia-
monds are cut from rock crystal.
AMETHYST.
Quartz of a clear purple or violet-blue color, of various degrees of intensity.
The color is supposed to be derived from manganese.
Fine specimens have been met with in the veins near Du-
mont. Small crystals at Nevada and Black Hawk. On Grape
Creek, Fremont County. In the Elk mountains. In geodes
on the Rio Grande River. Occasionally in South Park, asso-
ciated with smoky quartz, amazonstone and gothite.
24 Minerals of Colorado.
ROSE QUARTS.
A transparent, or nearly transparent variety of quartz, of a rose-red or
pink color. It usually occurs massive, and often much fractured.
Occuas in large masses at the summit of Floyd Hill ; near
Central City; on Bear and Soda Creeks.
QUARTZ. False Topaz. Citrine.
Color lemon-yellow, golden, or wine-yellow.
Found in the gravel on the divide between the Platte and
Arkansas, about the head of Plum Creek. On the west slope
of Pike's Peak, near its base.
CAIRNGORM. Smoky Quartz. Morion.
Color various shades of brown, passing into black. *
Abundant about Florissant, El Paso County, where it
occurs in "pockets" in the granite, associated with amazon-
stone, albite, gothite and fluorite. Some of the crystals are
of great size and extreme beauty. One crystal was found
which measured 4^ feet in length and 10 inches in diameter
at the base. A great many have been found from 20 to 30
inches in length. The crystals are usually transparent, and
have been used quite extensively in the manufacture of jew-
elry. Smoky quartz is also found at the head of Plum Creek ;
in the neighborhood of Larkspur, Summit and Monument;
at the head of Beaver Creek; on Cheyenne mountain; Elk
Creek, and in the nevadite of Chalk mountain.
JASPER.
Impure opaque colored quartz. The most common colors are brown, red
and yellow. Called Ribbon Jasper when the colors are in broad stripes or
bands. Egyptian Jasper when the colors appear in zones.
Red and yellow jasper is found very plentifully in Middle
and South Parks. A large proportion of the petrified wood
on the Platte and Arkansas divide, is jasper. Along the
sources of Cherry, Kiowa, and Bijou Creeks, it is quite com-
mon to find large trees, 60 or 70 feet in length, changed to
jasper. Ribbon Jasper is found near Larkspur ; also in Mid-
dle Park, at the junction of the Willow and Grand, in dark
green and yellow stripes. Egyptian Jasper near Larkspur.
CERARGYRIXE. Horn Silver. Chloride of Silver.
Isometric; occurs crystallized in small cubes and acicular prisms; gener-
ally massive and looking like wax; sometimes columnar, or bent col-
umnar; often in crusts. Lustre resinous, passing into adamantine. Color
pearl-gray, grayish-green, whitish, rarely violet-blue, colorless sometimes
when perfectly pure ; brown or violet-brown on exposure. Streak shining.
Transparent — feebly translucent. Fracture somewhat conchoidal. Sectile.
Comp., Chlorine 247, silver 75'3.
Common in the mines of Leadville, Silver Cliff and Rosita.
Occasionally found near the surface of veins about George-
town and elsewhere.
Minerals of Colorado. 25
CEXESTITE. Fibrous Heavy Spar. Sulphate of Strontia.
Orthorhombic; in modified rhombic prisms; crystals sometimes flattened;
often long and slender; also fibrous and radiated; sometimes globular;
occasionally granular. Lustre vitreous, sometimes inclining to pearly.
Color white, often bluish, and sometimes reddish. Streak white. Trans-
parent — subtranslucent. Brittle. Trichroism sometimes very distinct.
Phosphoresces when heated. H. 3-3'5. G. 3'92-3-95' Comp., sulphuric
acid 43'6, strontia 56'4.
Occurs as nodules in the Garden of trie Gods, which, upon
being broken, present a mass of beautiful blue crystals; occa-
sionally in fibrous masses. Celestite is used in the arts for
making nitrate of strontia, which is employed for producing
a red color in fire works.
SPHALtKRITK. Blende. Zinc-Blende. Sulphuret of Zinc.
Isometric; tetrahedral ; occurs crystallized and amorphous; botryoidal
and other imitative shapes; sometimes fibrous and radiated ; also massive,
compact. Cleavage, dodecahedral, highly perfect. Color brown, yellow,
black, red, green ; white or yellow when pure. Lustre resinous to ada-
mantine. Streak white to reddish-brown. Transparont to translucent.
Fracture conchoidal. Brittle. H. 3'5-4. G. 3'9-4'2. Comp., sulphur 33,
zinc 67.
Common in many of the gold and silver mines, and fre-
quently rich in gold or silver, although usually of but small
value. Fine cabinet specimens of black blende in the Maine
and other mines about Georgetown ; in the Coaley, Calhoun
and Delaware lodes, Gilpin County ; beautiful green crystals
in the L/ittle Giant lode, near L/awson, Clear Creek County.
Sulphuret of Molybdena.
Hexagonal ; occurs in flat hexagonal tables, with a cleavage parallel to
their terminal planes ; generally massive with a foliated structure, or'in
scales. Color pure lead-gray. Lustre metallic. Streak similar to color,
slightly inclining to green. Laminae flexible, but not elastic. Sectile, and
almost malleable. Leaves a gray trace on paper, a greenish trace on por-
celain. H. 1-1*5, being easily impressed by the nail. G. 4'4-4'8. Comp.,
sulphur 41, molybdenum 59.
About Georgetown ; Rock Creek, Gunnison County ; Boul-
der, Gilpin and Summit counties. Salts 'of molybdenum are
used to some extent in chemical operations.
HALITE. Common Salt. Kock Salt. Muriate of Soda. Chlorid of Sodium.
Isometric; usually occurs in cubical crystals; rarely in octahedrons;
faces of crystals sometimes cavernous. Massive and granular, rarely col-
umnar. Cubic cleavage. Lustre vitreous. Color white, sometimes yel-
lowish, reddish, bluish, purplish ; often colorless. Transparent — translu-
cent.* Fracture conchoidal. Rather brittle. Soluble. Taste purely
saline. H. 2'5. G. 2'l-2'257. Comp., chlorine 607, sodium 39'3, com-
monly mixed with some sulphate of lime, chlorid of calcium, etc.
Occurs in solution and as an incrustation about the salt
springs in South Park. Works were erected about 1868, and
considerable salt manufactured, but the company got into lit-
igation, and the works were abandoned.
26 Minerals of Colorado.
GYPSUM. Sulphate of Lime.
Monoclinic; crystals usually in right rhomboidal prisms, with beveled
sides; frequently the shape of an arrow-head ; eminently foliated in one
direction, and cleaving easily, affording laminae that are flexible but not
elastic; crystallized variety called selenite. Also occurs in« laminated
masses ; fibrous, with a satin lustre (satin-spar)- in stellated or radiating
forms, consisting of narrow laminae; also granular and compact (alabaster).
Color usually white; 'sometimes gray, yellow, reddish, brown, black.
Streak white. Transparent — opaque. H. l'5-2. G. 2'3. Comp., sulphu-
ric acid 46'5, lime 32'6, water 20'8.
Occurs in large beds of great purity in the South Park and
along the base of the mountains; specially available at Mor-
rison and Colorado Springs, where mills have been built for
the manufacture of gypsum into plaster-of-paris.
SEUENITK. Crystallized variety of Gypsum.
Occurs either in distinct crystals, or broad folia, the folia sometimes a yard
across, and transparent throughout. Cleaves easily, the plates bending in
one direction.
Occurs in grouped and single crystals on Box Elder Creek,
Ivaramie County ; at River Bend, on the K. P. Railway, in
fine crystals ; on Bear Creek, near Morrison. Selenite, in
thin folia, was formerly extensively used in windows, and is
still used for that purpose by the Mexicans in the Socorro
mountains.
SATIN SPAR. Fibrous Gypsum.
Occurs in fine fibrous masses, having a satin lustre, and the pearly opales-
cence of the moonstone.
Fine white masses at Morrison. Pink and white near
Quick's ranch, on Plum Creek. Satin Spar is used in the
manufacture of beads and other ornamental articles.
ALABASTER. Granular Gypsum.
Fine-grained, and either white or delicately shaded.
On Box Elder Creek, in immense deposits. At Morrison,
white and mottled. At Colorado Springs, pink and white.
At Canon City, pure white.
GADOI^INITB. Eakins, Proc. Colo. Sc. Soc., 1885.
Orthorhombic; in oblique rhombic prism; occurs also in small masses.
Color black, greenish-black ; dull externally, internally shining; in thin
splinters nearly transparent, and grass-green to olive-green. Streak green-
ish-gray. Lustre vitreous. Subtranslucent — opaque. Fracture conch-
oidal. H. 6'5-7. G. 4-4'5. Analysis of Colorado mineral by Eakins:
Silica 22'13, alumina 2'34, protoxyd of iron T13, thoria Q'&9, oxide of
cerium ll'lO, oxide of lanthanum and didymium 21/23, erbium 12'74,
yttria 9'50, oxide of iron 10'43, beryllium 7'19, lime 0'34, magnesia 0' 14,
potassa 0'18, soda 0'28, water 0'86.
Occurs in small fragments on Devil's Head mountain,
Douglas County. This is the first observed occurrence of the
mineral in this country, and was found by Mr. W. B. Smith,
of the U. S. Geological Survey.
Minerals of Colorado. 27
Silicate of Zinc.
Orthorhorabic ; occurs in obtuse rhorabohedrons, and in long quadrilateral
tables; also stalactitic, mammilated, botryoidal, fibrous, massive and gran-
ular. Lustre subpearly, sometimes adamantine. Color white ; sometimes
with a delicate bluish or greenish shade ; also yellowish to brown. Streak
white. Transparent — translucent. Brittle. Fracture uneven. Pyroelec-
tric. Double refraction strong. H. 4'5-5. G. 3'16-3'49. Comp., silica
25'0, oxyd of zinc 67'5, water 7'5.
Occurs as a delicate white incrustation in the mines of
Leadville.
H. F. and H. A. Kellar, Am. Ghent. Jr., vol. 2.
Radiated structure. Color dark lead-gray. Lustre bright. Soft. G. 6'29.
Analysis of mineral from Lillian Co's mines: sulphur 15'21, bismuth 32'62,
lead 43'94, silyer 5*78, copper trace.
Occurs in the mines of the Lillian company on Printer Boy
Hill, near Leadville, in nodules of various sizes up to several
feet in diameter, more or less oxidized. The fresh mineral
has a fine-grained crystalline structure, and steel-gray color.
GRAPHITE. Plumbago. Black Lead.
Hexagonal ; in flat six-sided tables. Commonly in imbedded, foliated, or
granular masses. Perfect cleavage. Color iron-black to dark steel-gray.
Streak black and shining. Lustre metallic. Soils paper. Sectile ; thin
laminae flexible. Feel greasy. H. 1-2. G. 2'0891. Comp., pure carbon,
with often a little oxyd of iron mechanically mixed.
At Pitkin, in beds 2 feet thick; large masses at Trinidad;
small veins at Maysville, but very impure in each locality.
Graphite is largely employed under the name of Plumbago,
or Black Lead, for the manufacture of crucibles and other re-
fractory articles ; foundry facings, lubricating compounds,
electrical supplies, stove-polish, pencil leads and pigments.
It has an average spot value of 8 cents a pound.
SCHEEUTTE. Tungstate of Lime. Sittiman, Am. Jr. Sc., June, 1877.
Tetragonal ; primary form a right square prism ; occurs in attached and
imbedded four-sided pyramids, approaching nearly to the octahedron ; also
occurs reniforrn with columnar structure, and massive granular. Lustre
vitreous inclining to adamantine. Color white, yellowish-white to orange.
yellow, brownish, greenish. Streak white. Transparent to translucent,
H.- 4-5-5. G. 5'9. Comp., lime 19'4, tungstic acid 80'6.
Gold-bearing scheelite occurs in the Golden Queen mine,
Lake County.
Silicate of Vanadium. Genth, Am. Phi. Soc., Phila., 1877.
Micaceous in structure; scales minute, often arranged in stellate or fan -
shaped groups. Basal cleavage perfect. Color dark clover-brown to
greenish-brown. Analysis of Boulder County mineral by Genth : silica
56-74, alumina 19'62? vanadium 7'78, iron oxide 3'84, magnesia 2'63, po-
tassa 8'11, with traces of manganese, soda, lithium and water.
In the mines of Magnolia District, Boulder County, as a
thin earthy incrustation of a grayish to olive-green color on
calaverite; also inclosed in quartz, and giving it a green color.
28 Minerals of Colorado.
HESSIXE. Telluric Silver. Silliman, Am. Jr. Sc., July, 1874. Genth, Am.
Phi. Soc., 1874.
Orthorhombic ; massive ; compact or fine-grained ; rarely coarse granular.
Lustre metallic. Color between lead-gray and steel-gray. Sectile and
malleable, laminating into thin scales under the pestle, leaving on the
agate surfaces metallic streaks of plumbago-like color. H. 2-3*5. G. 8*3
8'6. Analysis by Genth of mineral from the Red Cloud mine, Boulder
County : gold 0*22, silver 59;91, copper 017, lead 0.45, zinc trace, iron 1/35,
tellurium 37*86. An auriferous variety gave: gold 13*09, silver 50'36, tel-
lurium 34-91. *
Occurs abundantly in the Slide and Prussian mines, and
sparingly in other mines at Gold Hill and Sunshine, Boulder
County.
"WOlrFR. AMITK. Tungstate of Manganese.
Orthorhombic ; primary form a right rhombic prism ; occurs massive and
crystalized ; irregular lamellar ; coarse divergent columnar ; massive gran-
ular, the particles strongly coherent. Lustre submetallic. Color dark
grayish or brownish black. Streak dark reddish brown to black. Some-
times weak magnetic. H. 5-5*5. G. 7*1-7*55. Comp., tungstic acid 75*92,
Srotoxide of iron 19*35, protoxide of manganese 4*73.
ebrand mentions its occurrence in the Missouri mine,
Hall Valley, Park County, Occurs near Boulder.
UR.ANINITE. Pitchblende. Protoxyd of Uranium. Am. Jr. Sc., 1873.
Isometric ; usually massive and botryoidal ; also in grains. Structure
sometimes columnar, or curved lamellar. Lustre submetallic to greasy or
pitch-like, and dull. Color grayish, greenish, brownish, velvet-black.
Streak brownish, a little shining. Fracture conchoidal, uneven. H.
5*5. G. 6*4-8. Comp., protoxyd of uranium 32*1, sesquioxyd 67*9, but
analyses vary much through mixture with other substances.
A pocket of uraninite was encountered in the Wood lode,
Central City, in 1873, nearly all of which was shipped to Eng-
land by Kichard Pearce, esq., of the Boston and Colorado
Smelter, and sold for $1.50 per pound. Thin seams of the
mineral occur in Jefferson county. A mass of uraniuite
was encountered in the Jo Reynolds mines, Clear Creek
County, in 1885, but unfortunately, it was mixed with the
silver pre from the mine, and milled, the adulteration caus-
ing a serious loss to the miners. But two or three specimens
were saved, one of which is in the collection of the compiler,
also specimens from the Wood lode.
Uranium has the color and lustre of silver, but is harder,
and gives out sparks when struck with a hammer. It oxid-
izes gradually when exposed to the air, burns when heated
on platinum-foil, and is dissolved by nitric acid. Its specific
gravity is 18*7. Its compounds are used in considerable
quantities in chemical operations and in porcelain painting,
affording a yellow or black color, according to the process of
baking.
Minerals of Colorado. 29
Telluride of Gold. Genth, Am. Phi. Soc.^ Phila., 1877.
Occurs massive and in small crystals. Color bronze-yellow. Streak yel-
lowish-gray. Brittle. Fracture uneven, inclining to subconchoidal. Anal-
ysis of Colorado mineral by Genth: tellurium 57'32, gold 38'75, silver
3*03, oxyd of vanadium 0'05, protoxyd of iron 0'03, alumina, magnesia,etc.,
0-55, quartz 4'96. Theoretical formula, tellurium 57'93, gold 39'01, sil-
ver 3'C6.
In the Slide, Keystone J Mountain Lion and other mines, in
Boulder County. Small imperfect crystals imbedded in
quartz.
(new.} Genth, Am. Phi. Soc. Phil., 1877.
Tn delicate radiating tufts ; also in very minute prismatic crystals. Color
between straw and lemon-yellow, inclining to greenish-yellow. Contains
iron and tellurium.
Found as a coating on quartz associated with native tellu-
rium and tellurite, at ihe Keystone mine, Magnolia District,
Boulder County.
(new.) Variety of Native Tellurium. Genth, Am. Phi. Soc.
Phil., 1877.
Occurs in thin plates. Color dark gray. H. 3. G. 4'005. Analysis of
Colorado mineral by Genth : tellurium 55'54, quartz 35'91, alumina and
iron oxyd 6'14, manganese and iron oxide 0*19, calcium and iron oxide
0-26, gold 1-53, silver 0'25.
Occurs in the Mountain Lion mine, Boulder County, from
which it was named by Berdell.
(new). Telluride of Mercury. Genth, Am. Phi. Soc., 1877.
Occurs in radiating tufts of very minute acicular or capillary crystals.
Color white. Lustre silky. Contains mercury and tellurium.
Qccurs as a product of the decomposition of coloradoite in
the upper part of the Keystone, mine, Magnolia District, Boul-
der County. Named from Magnolia District.
Tellurious Acid. Genth, Am. Phi. Soc. Phil., 1877.
Occurs in prismatic crystals and in spherical masses, radiated in structure ;
also as an incrustation. Crystals cleavable in one direction. Color yellow
to white.
In the John Jay mine, Boulder County, as an incrustation
in cracks in native tellurium, and in minute prismatic crys-
tals.
CHRYSOCOLLA. Silicate of Copper.
Cry ptocrystal line ; often opal-like or enamel-like in texture; earthy; in-
crusti/ig or filling seams; sometimes botryoidal. Color various shades of
blue, passing into green. Streak, when pure, white. Translucent to
opaque. Fracture conchoidal. H. 2-4. G. 2'2. Comp., silica 34'2, oxyd
of copper 45'3, water 20'5. An analysis by Genth of what was supposed
to be chrysocolla, from Bergen Park, gave 33.85 alumina, and 5'40 of cop-
per oxide, which corresponds to allophane with probably some chrysocolla.
Found in copper lodes on Bear Creek; near Canon City ;
at the head of San Luis Valley; in the Champion lode, Idaho
Springs, and in small quantity in many other localities.
30 Minerals of Colorado.
Cobalt Bloom. Ked Cobalt Ore. Cobalt Ochre. W. F.
Hillebrand, Am. Jr. Sc., May, 1884 ; Proc. Col. Sic. Soc., Vol. I.
Monoclinic; in acicular diverging crystals, modified at the edges, and
whose form is a right oblique-angled prism ; also found in globular and
reniform shapes, having a drusy surface and a columnar structure; some-
times stellate; also pulverulent and earthy, incrusting. Lustre vitreous
to earthy. Color crimson and peach-red, sometimes pearly or greenish-
gray ; red tints incline to blue perpendicular to cleavage face. Streak a
little paler than the color; the dry powder deep lavender-blue. Thin
laminae flexible in one direction. Sectile. H. rS-2'5, G. 2'94. Comp.,
arsenic acid 38'43, oxyd of cobalt 37*55, water 24'02.
A product of the alteration of lollingite in the mines on
Teocalli Mountain, Brush Creek, Gunnison County.
AMPHIBOUE. Hornblende.
Monoclinic; crystals often long and bladed, sometimes stout; fibrous, col-
umnar, coarse or fine, fibers often like flax, when it is known by other
names. Color between black and white, through various shades of green,
inclining to blackish green. This species has numerous varieties, differing
much in external appearance and in composition. Silica, alumina, lime,
iron and magnesia enter into the composition.
Hornblende is an essential constituent of many of the rocks
of the mountainous region, such as hornblende gneiss, a
tough dark rock, which is quite abundant, seyenitc, trap., etc,
It is occasionally found massive and crystallized.
ASBESTOS. A variety of Amphibole.
Occurs in fine fibrous masses, of light color.
In the Star of the West and other lodes at the head of
of North Boulder Creek, Boulder County, associated with
galena. Near Maysville, Chaffee County, in mineral veins.
Asbestos was woven into cloth by the ancients, which, from
its incombustibility, was used to wrap the bodies of the dead
before placing them on the funeral pile, by which the ashes
were preserved for subsequent preservation in vases. Cloth-
ing was manufactured from it, which was cleansed by burn-
ing instead of washing. Its chief use now is for making tire-
proof roofing, boiler lining and lire proof safes.
TttEMOUTti.
The name given to the white or light greenish variety of Amphibole. It
occurs in long slender blades, or in columnar and radiated aggregations.
In white, radiated masses near Maysville, Chaffee County.
ACXIJJOWTE. A variety of Amphibole.
Fibrous, columnary or massive. Color bright green or grayish-green.
On Bear Creek, Jefferson County, in fibrous aggregations,
of a dark green color. In the mineral veins at the head of
North Boulder Creek, and in the Partridge lode, on Coal
Creek, Boulder County. Light green and bluish-green on
Mount Ouray. Specimens of the amphibole minerals in the
compiler's collection.
Minerals of Colorado. 31
(new.} Telluride of Mercury. Genth, Am. Phi. Soc.,
Phtta., 1877.
Massive ; granular, sometimes imperfectly columnar (due to admixed syl-
vanite?) Luster metallic. Color iron-black inclining to gray. Fracture
uneven to subconchoidal. Theoretical composition, tellurium 39'02, mer-
cury 60*98. Analyses of mineral from the Keystone and Smuggler mines
by Genth, varied a great deal on account of an admixture of gold and
quartz. That from the Keystone mine carried Irom 8 to 46 per cent of
gold and quartz, with small amounts of alumina, iron, vanadium and mag-
nesia. Mineral from the Smuggler mine contained quartz and gold, 3'05,
tellurium 34*49, mercury 48*74, gold 7*67, silver 7*18, iron 0*92, copper 0*16,
zinc 0-50. H. 3. G. 8'627.
Occurs sparingly in the Keystone, Smuggler and Mountain
Lion mines, Boulder county.
Soda Alum.
Occurs in white fibrous and pulverulent masses. Resembles fibrous gyp-
sum, but harder. H.3. G. 1'88. Reported analysis of Colorado mineral :
sulphuric acid 38*35, sulphate of alumina 14'66, sulphate of soda 4*35
water 42*64.
F. F. Chisolmn reports its occurrence in a lode one-and-a-
half miles shuth-east of Red Cliff.
Anhydrous Silicate of Zinc.
Rhombohedral ; occurs in regular six-sided prisms; also massive, fibrous
and in grains. Color whitish, yellowish, flesh-red, apple-green and dark-
brown. Streak same as color. Luster vitreo-resinous. Transparent to
opaque. Brittle. Fracture coochoidal. Double refracting. H. 5*5. G.
3-84-4*18. Comp., silica 27*1, oxyd of zinc 72*9.
Occurs sparingly at the head of the Rio La Plata as a pale
green crystalline mineral filling cavities in other zinc ores.
(new.) Sulphate of Manganese. M. W. lies, American Chemical
Journal, 1881.
Occurs in thick prisms which are frequently terminated by truncated pyr-
amids. Friable. Taste bitter, astringent. Color white. Soft. G. 2*16.
Analysis by lies: protoxyd of iron 4*18, oxyd of zinc 5*97, protoxyd of
manganese 22*31, sulphuric acid 36*07, water 31*60.
Occurs in veins from two to eight inches wide in the Mc-
Donnell lode, Middle Swan Creek, Hall Valley, Park county.
Named after Dr. M. W. lies.
CHAI.CAN'THITB. Blue Vitriol. Sulphate of Copper.
Triclinic; rarely found in distinct crystals; generally occurs stalactitic,
reniform, amorphous and pulverulent. Color Berlin-blue to sky-blue of
various shades ; sometimes greenish ; turns white on exposure. Translu-
cent. Luster vitreous. Taste metallic and nauseous. Comp., sulphuric
acid 32-1, oxyd of copper 31*8, water 36*1.
Occurs in a number @f mines in Hall Valley, Park county;
in the Whale tunnel, near Idaho Springs; in a deposit below
Black Hawk. It is formed by the decomposition of iron and
copper pyrites. When purified it is employed in cotton and
linen printing, and for various other purposes in the arts. It
is sometimes employed to prevent dry rot in wood.
32 Minerals of Colorado.
SCHIR.MBR.IXE. (new.) Bismuth Silver. F. A. Genth, Proc. Am. Phi.
Soc., Phila., vol. 14, 1874.
Massive, without crystalline structure ; fine granular. Fracture uneven.
Brittle. Color lead-gray, inclining to iron-black. Luster metallic. Soft.
G. 6'737. Analysis by Genth : lead 12'76, silver 2475, bismuth 47'27, zinc
0'13, iron 0'07, sulphur 15'02.
First noticed in the Treasure Vault mine, Geneva district,
Clear Creek county, from whence the mineral came which
was analyzed by Mr. Genth. It occurs in all the older veins
in the district, finely disseminated through quartz. It has
never been noticed in the newer or subsequently-formed veins
which carry a large amount of galena, very little of which is
found in the bismuth-bearing veins. Dana's Mineralogy
credits the mineral to the lied Cloud mine, Boulder county,
where he says it "occurs with other tellurium minerals."
The location is erroneous, as the mineral has never been found
in that county. It was named after J. F. L. Scbirmer. The
schirmerite of Endlich was found to be a mixture of petzite
and some other minerals, and therefore not entitled to a name.
Specimens in compiler's cabinet.
Graphic Tellurium. Telluride of Gold and Silver. Silli-
man, Am. Jr. Sc., July, 1874, and Clarke, Oct., 1877 ; Genth, Am. Phi.
Soc., Phila., 1874.
Monoclinic ; occurs in indistinct and minute circular crystals, modified at
the edges and angles, and often grouped in rows, forming triangular figures
like letters; also massive, imperfectly columnar, granular. Cleavage in
two directions, nearly at right angles; one very perfect; Luster metallic.
Color steel-gray to tin-white and brass-yellow. Streak like color. H. l'5-2.
G. 5'732-8'28. Analysis by Genth of mineral from Red Cloud mine, Gold
Hill: gold 24-83, silver 13'05, tellurium 56'31, copper 0'23, zinc 0'45, iron
3'28, sulphur T82, selenium trace, quartz 0'32. Analysis of mineral from
Grand view mine, by Clarke : tellurium 52'96, gold 26'39, silver 10'55,
iron 4'45, sulphur 5*62.
Quite abundant in crystals and crystalline masses dissem-
inated .through quartz, in the the Red Cloud, Prussian, Cold
Spring and other veins at Gold Hill; in the American and
Grand View veins at Sunshine, Boulder county. Specimens
in compiler's cabinet.
Konig, Am. I hi. Soc., Phila., 1877.
Orthorhombic; usually in tabular prisms; often lengthened into strips
with parallel sides; easily cleavable. Luster submetalhc, pearlv. Color
bronze-yellow, gold-yellow, brownish. Powder like mosaic gold. Trans-
lucent and slightly elastic in thin leaves. H. 3. G. 3'324. Analysis by
Konig of Colorado mineral ; silica 34'68, titanic acid 13'58, zirconia 2'20,
sesquioxyd of iron 5'56, alumina 0'70, protoxyd of iron 26'10, protoxyd of
manganese 3'48, soda 2'54, potassa 5'01, water 3'54, magnesia 0'30, oxyd of
copper 0-42, tantalic acid (?) 0'80.
Beautiful specimens are found in veins on Cheyenne Moun-
tain, in quartz, associated with arfvedsonite and zircon.
Specimens in compiler's collection.
Minerals of Colorado. 33
GARXBT.
Isometric; occurs in dodecahedrons, also in trapezohedrons, and both
forms are sometimes variously modified. Cleavage parallel to the faces of
the dodecahedron, rather distinct. Also found massive granular and
coarse lamellar. Color red, brown, yellow, white, apple-green, black;
some red and green colors often bright. Streak white. Lustre vitreous —
resinous. Transparent — subtranslucent. Fracture subconchoidal, uneven.
H. 6.5-7.5. G. 4'13. Composition varies, silica, alumina, iron, lime, etc.
There are three prominent varieties, based on the nature of the com-
position. (See Spessartite and Almandite.}
Red, brown and black garnets occur quite frequently in the
Archean. A reddish-brown garnet between Georgetown and
Green Lake,, and on Saxon Mountain. Quite abundant near
the head of Fall River, on Trail Creek, Bergen Park, Central
City, and other localities. A black variety in a vein near
Hoosier Pass. Small garnets, probably almandite, of beauti-
ful color, are found in quantities in the gold washings at Fair-
play and Breckenridge; impure alnwndite near Salida (p. 48).
Spessartite at Nathrop in rhyolite, and in the Grand Canon
of the Arkansas (p. j6).
UMONITB. Brown Iron Ore. Brown Ochre.
Usually in stalactitic and botryoidal or mammilary forms, having a fibrous
or subfibrous structure; also concretionary, massive, and occasionally
earthy. Lustre silky, often submetallic; sometimes dull and earthy.
Color of surface of fracture various shades of brown, commonly dark, and
none bright ; sometimes with a nearly black varnish-like exterior ; when
earthy, brownish-yellow, ochre-yellow. Streak yellowish-brown. H. 5 —
5'5. G. 3'6-4. Comp., sesquioxyd of iron 85'6, water 14*4.
A brown hematite of excellent quality is found in the Hot
Springs mine, Saguache County, which has been quite exten-
sively mined. At Villa Grove, in the same county. A bog
ore is found near Crested Butte. Analyses of ore from these
localities have been made at the State School of mines
Hot Villa Crested
Springs. Grove. Butte.
Silica 9-33 10'19 2'50
Water lO'ol 13'57 23'97
Alumina 3'43 3'60 0'28
Oxide of Manganese 0'35
Lime 0-83 0'45 0'22
Magnesia 0'06 0'22 0'12
Peroxide of Iron 75'23 70'39 72'47
Phosphoric acid 0'071 0'92 0'333
Sulphur 0-019 0'18
99-830 99-62 99'893
"This ore is a chemical curiosity," says Prof. Chauvenet, of
the State School of Mines, in speaking of the hematite' from
Crested Butte. "containing at once figures on certain constit-
uents which are phenomenal for highness and lowness respect-
ively. After burning this ore would be enriched to nearly
34 Minerals of Colorado.
sixty-seven per cent of metallic iron by the loss of water and
organic matter." The ore is said to approximate to half a
mile square in extent, with an uncertain depth.
Limonite exists in numerous other localities — between
South Boulder and Coal Creeks; on Bear Creek; in South
Park; at Trinided; beautiful specimens on Little Thompson,
at the foot of the mountains.
Carbonate of Soda.
Monoclinic. Vitreous to earthy. White, sometimes gray or yellow.
Taste alkaline. H. 1-1-5. G. T423. Comp., carbonic acid 26'7, soda
18'8, water 54'5.
About twelve miles south-west of Denver, between Turkey
and Bear Creeks, are four small lakes containing in solution
a large amount of soda.
MAGNETITE. Magnetic Iron Ore. Octahedral Iron Ore.
Isometric; octahedrons and rhombic dodecahedrons: cleavage octahedral.
Massive, and in particles of various sizes, sometimes impalpable. Lustre
metallic — submetallic. Color iron-blacK. Streak black. Fracture sub-
conchoidal, shining. Brittle. Strongly magnetic, sometimes possessing
polarity. H' 5*5-6'5. G. 4'9-5'2. Comp., oxygen 27'6, iron 72'4.
The Calumet mine, ChafFee County, is the only iron mine
in the State producing magnetite, upon which the steel
works at Pueblo are largely dependent. The mine has been
opened to a depth of about 300 feet, and to a rmich greater
distance horizontally. Analysis by School of Mines, Golden:
Silica 7'04, alumina T90, peroxyd of iron 56'76, protoxyd of iron 26'88, bisul-
phide of iron 1'14, lime 1'59, magnesia T70, phosphoric acid 0*16, titanic acid
trace.
At Caribou a seven-foot vein of very pure ore. On Elk
Creek.
HEMATITE. Specular Iron. Red Ochre.
Rhombohedral ; in complex modifications of a rhombohedron ; crystals
occasionally thin tabular; also occurs granular, botryoidal, and stalactitic
shapes; lamellar, the laminae variously bent, and thick or thin. Lustre
metallic and occasionally splendent; sometimes earthy. Color dark steel-
gray or iron-black ; in very thin particles blood-red by transmtited light ;
when earthy, red. Streak cherry-red or reddish-brown. Sometimes at-
tractable by the magnet, and occasionally even magnetic-polar. H. 5'5-
6'5. G. 4'5-5'3. Comp., oxygen 30, iron 70.
An impure hematite occurs in the Hawkins bank, ChafFee
County. The following analysis of the ore was made at the
State School of mines:
Silica 22-33, water 3'10, alumina 3.06, lime 0'08, magnesia 0'06, peroxide of
iron 70'40, phosphoric acid 0'614, sulphur 0'056.
Occurs as an ochre near Florissant, with gothite, microcline,
quartz, fluorite, etc. A micaceous variety quite abundant on
Left Hand Breek, Ward District, Boulder County, and is
found in small quantities in numerous localities.
Minerals of Colorado* 35
MUSCOVITE. Common Mica. Potash Mica. Oblique Mica.
Orthorhombic ; occurs in oblique rhombic prisms with basal cleavage ;
usually in thinly foliated masses ; folia often aggregated in stellate, or
globular forms. Lustre more or less pearly. Color white, gray, brown,
hair-brown, pale green, yiolet, yellow, dark olive-green, rarely rose-red ;
often different for transmitted and reflected light, and different also in
vertical and transverse directions. Streak uncolored. Transparent to
translucent. Thin lamina flexible, elastic, tough. Double refracting.
H. 2-2.5 G. 2.75-3.1. Comp., silica 46, alumina 37, potash 9, peroxyd of
iron 4, fluoric acid 1, water 2.
A constituent of much, of the Archean rocks, and occasion-
ally found in quite large masses. Several attempts have been
made to develop deposits in Jefferson and Clear Creek Coun-
ties, but without success. Near Canon City quite a large de-
posit which has been worked with limited success.
Magnesia-Mica. Hexagonal Mica.
Hexagonal ; prisms usually tabular, with perfect basal cleavage. Often in
disseminated scales, sometimes in massive aggregations or clsavable scales.
Lustre splendent, and more or less pearly on a cleavage surface, and some-
times submetallic when black ; lateral surface vitreous when smooth and
shining. Colors usually green to black, often deep black in thick crystals;
thin laminae green, blood-red, or brown by transmitted light ; rarely
white. Streak uncolored. Transparent to opaque. Tough and elastic.
H. 2.5-3. G. 2.7-3.1. Comp., varies, silica 39, alumina 15, peroxyd of
iron 8, magnesia 24, soda 1, potash 9, water 1, flluorine, chlorine, etc.
The mica of the Archean rocks is mainly biotite. It also
occurs in the dike rocks.
BISMUXIXE. Carbonate of Bismuth.
In implanted acicular crystallizations (pseudomorphs); also incrusting or
amorphous ; pulverulent. Lustre vitreous when pure ; sometimes dull.
Color white, mountain-green, and dirty siskin-green; occasionally straw-
yellow and yellowish-gray. Streak greenish-gray to colorless. Subtrans-
lucent— opaque. H. 4-4.5. G. 6.86-6.909.
Near Cummens City, North Park. In the mountains west
of Fort Collins, where a number of veins have been prospect-
ed. In the L,as Animas mine, Gold Hill. In white quartz
on Guy Hill, Jefferson County, with bismuthinite.
Sulphuret of Manganese.
Isometric; in cubes and octahedrons. Cleavage, cubic perfect, crystals
sometimes cruciform, made of five combined octahedrons. Usually mass-
ive. Lustre submetallic. Color iron-black, tarnished brown on exposure.
Streak green. H. 3'5-4. G. 3'95-4'04. Comp., sulphur 36'7, manganese
63-3.
A ' 'pocket' ' of this mineral was encountered in sinking the
shaft on the Queen of the West mine, Summit County, about
300 feet from the surface. Occasionally crystals are met with.
The only immediate associate mineral is rhodochrosite, al-
though the mine carries galena, pyrite and argentite. The
alabandite carries about 30 ounces of silver to the ton. This
is the first published instance of its occurrence in America.
36 Minerals of Colorado.
SPESSAR.XITK. Manganese- Alumina Garnet. W. Cross, U. S. Geo.
Sur., Am. Jr. Sc., June, 1866.
Isometric ; occurs in dodecahedrons, also in trapezohedrons, and both
forms are sometimes variously modified. Cleavage parallel to the faces of
the dodecahedron, rather distinct. Also found massive granular and
coarse lamellar. Color dark hyacinth-red, sometimes with a shade of
violet, to brownish-red. Streak white. Lustre vitreous — resinous. Trans-
parent— subtranslucent. Fracture subconchoidal, uneven. H. 6.5-7.5.
G. 4'13. Analysis of Nathrop mineral by L. G. Eakins: silica 35.66,
alumina 18.55, sesquioxyd of iron .32, protoxyd of iron 14.25, protoxyd of
manganese 29.48, lime 1.15, potassa .27, soda .21, water .44.
Occurs at Nathrop in lithophyses of rhyolite, associated
with topaz. In a similar rock in the Grand Canon of the Ar-
kansas.
EPIDOXE.
Monoclinic; in right rhomboidal prisms, more or less modified, often
with six or more sides ; also fibrous, divergent or parallel ; also granular,
particles of various sizes, sometimes fine granular and forming rock
masses. Lustre vitreous, inclining to pearly or resinous. Color pistachio-
green to brownish-green, greenish-black to black ; sometimes clear red and
yellow; also gray and grayish-white. Subtransparent— opaque ; gener-
ally subtranslucent. Fracture uneven. Brittle. H. 6-7. G. 3.25-3.5.
Comp., silica 37.0, alumina 26.6, lime 20.0, protoxyd of manganese 0.6,
water 1.8.
Of frequent occurrence in the Archian, usually massive.
Very good crystals have been found on Floyd Hill and on
Bear Creek.
MALACHITE. Green Carbonate of Copper.
Monoclinic; rarely occurs crystallized ; usually massive or incrustating,
with surface tuberose, botryoidal or stalactitic, and structure divergent;
often delicately compact fibrous, and banded in color; frequently granular
or earthy. Lustre of crystals adamantine, inclining to vitreous ; fibrous
varieties more or less silky ; often dull and earthy. Color bright green.
Streak pale green. Translucent, subtranslucent, opaque. Fracture sub-
conchoidal, uneven. H. 3.5.7—4. G. 3.7 — 4.01. Comp., carbonic acid
19.9, protoxyd of copper 71.9, water 8.2.
Of general occurrence throughout the State near the sur-
face of mineral veins, but in small quantities, and usually as
incrustations.
CER.USSIXE. Carbonate of Lead. White Lead Ore.
Orthorhombic ; crystals usually thin, broad and brittle; sometimes stout;
rarely fibrous; often granular, massive and compact; sometimes stalactitic.
Lustre adamantine, inclining to vitreous or resinous ; sometimes pearly;
frequently submetallic if the colors are dark, or from a superficial change.
Color white, gray, grayish-black, yellowish, sometimes tinged blue or
green by some of the salts of copper. Streak uncolored. Transparent —
subtranslucent. Fracture conchoidal. Very brittle. H. 3-3'5. G. 6.465-
6.480. Comp., carbonic acid 16.5, oxyd of lead 83.5.
Abundant at Leadville, and occasionally in fine crystalline
masses. Also abundant in numerous localities south of Lead-
ville. Occurs in small quantities at the surface of silver
veins in the Archian.
Minerals of Colorado. 87
TIXAIVI'TE. Sphene.
Monoclinic; in very oblique rhombic prisms; crystals usually thin, with
sharp edges. Cleavage in one direction sometimes perfect. Occasionally
massive. Color grayish-brown, gray, brown or black ; sometimes yellow
or green ; streak uncolored. Lustre adamantine to resinous. Transparent
to opaque. Brittle. H. 5-5'5. G. 3'4-3'56. Comp., silica 30'5, titanic
acid 41-3, lime 28'2.
Occurs in crystals in the augitic rock on Italian Mountain,
Gunnison County.
CHRYSOWTE. Olivene. Peridot.
Orthorhombic; in right rectangular prisms, having perfect cleavage par-
allel with the smaller lateral plane ; usually in imbedded grains, of an ol-
ive-green color, looking like green bottle glass ; also yellowish-green.
Transparent to translucent. Looks much like glass in the fracture, except
in the direction of the cleavage. H. 6-7. G. 3'33-3'5. ' Comp., silica 38'5,
magnesia 48'4, protoxyd of iron 1T2, oxyd of manganese 0'3, alumina 0'2.
Occurs in the basalt of Bastion Peak.
PYROMOR.PHITE. Green Lead Ore. Phosphate of Lead.
Hexagonal ; occurs in six-sided prisms, usually modified on the edges, and
frequently striated horizontally ; often globular, reniform, and botryoidal,
with a subcolumnar structure; also fibrous and granular. Lustre resinous.
Color green, yellow and brown of different shades; sometimes wax-yellow
and fine orange-yellow ; also greenish-white or milk-white. Streak white,
sometimes yellowish. Subtransparent-stibtranslueent. Brittle. II. 3'5-4.
G. 6'5-7'l. Comp., phosphoric acid 15*7, oxyd of lead 74'1, chlorine 2'6,
lead 7-6
Sparingly in the mines at L/eadville, and in the Astor and
Freeland mines, Clear Creek County.
Hexagonal ; occurs in six and twelve sided prisms, with
plane or modified summits. Prismatic cleavage, distinct. Also massive,
compact, and thin columnar. Lustre vitreous, greasy; a little opalescent
in some varieties. Colorless, white or yellowish; also when massive,
dark green, greenish or bluish-gray, brownish and brick-red. Transpa-
rent-opaque. Fracture subconchoidal. H. 5*5-6. G. 2'5-2'65. Comp.,
silica 44-2, glucina 337, soda 16'9, potash 5'2.
In the basalt of Bastion Peak and elsewhere in the Elkhead
Mountains.
AXIVABKRGITE. Nickel Ochre. Nickel Green. Arseniate of Nickel.
Monoclinic; in capillary crystals; also massive and disseminated. Color
fine apple-green, Streak greenish-white. Fracture uneven, or earthy.
Soft. Comp., arsenic acid 38'6, oxyd of nickel 37'2, water 24'2.
Occurs as an alteration product of niccolite in the Gem
mine, on Pine Creek, Fremont County.
CHAI,COCIT'E. Vitreous Copper Ore. Copper Glance.
Orthorhombic ; in six-sided prisms, variously modified ; also massive,
structure granular, or compact and impalpable. Lustre metallic. Color
and streak blackish lead-gray ; often tarnished blue or green. Fracture
conchoidal. Streak sometimes shining. H. 2'5-3. G. 5'5-5'8. Comp.
sulphur 20'2, copper 79'8.
Abundant in copper veins near Canon City; also in Bergen
Park and on Bear Creek, Jefferson County.
38 Minerals of Colorado.
XAOYAGIXE. Black Tellurium. Foliated Tellurium.
Tetragonal ; occurs in small six-sided tables with a basal cleavage; also
massive-granular, but generally foliated. Lustre metallic, splendent.
Streak and color blackish lead-gray. Flexible in thin laminse. H. 1-1*5.
G. G-85-7'2. Comp., tellurium 15 to 32, sulphur 3 to 9, lead 50 to 60, gold
5 to 12.
Occasionally met with in the tellurium mines of Boulder
County.
GAUENI'FE. Galena. Sulphuret of Lead.
Isometric; occurs crystallized in the cube, octahedron, and in numerous
combinations of these, with planes of other figures; also in amorphous
masses with a lamellar structure; frequently granular ; occasionally fibrous.
Cleavage cubic. Lustre metallic. Color and streak pure lead-gray. Sur-
face of crystals occasionally tarnished. Sectile. Easily pulverized, and
easily frangible. H. 2-5-2'75. G. 4'25-7'7: Comp., sulphur 13*4, lead 86'6.
Of general occurrence throughout the mining regions, and
usually containing a profitable per cent of silver. Good crys-
tals only occasionally met with. Specially fine clusters have
been taken from the Dunderberg and Terrible mines, George-
town, and from the Running, Calhoun and Glennan mines,
in Gilpin County.
DECMENITE.
Occurs massive, botryoidal, nodular, stalactitic ; sometimes traces of a col-
umnar structure. Lustre of fresh fracture greasy. Color fine deep red to
yellowish-red and brownish-red ; also leather-yellow. Streak orange-yel-
low to pale yellow. H. 3-4. G. 5'6-5'81. Comp., vanadic acid 47, oxyd
of lead 53.
Occurs in the Evening Star mine, L/eadville, of dark red to
yellow color.
WIXHER.ITE. Carbonate of Baryta.
Orthorhombic ; in modified rhombic prisms and in six-sided prisms ter-
minated with pyramids; also in globular, tuberose and botryoidal forms ;
structure columnar, granular or amorphous. Lustre vitreous, inclining to
resinous, on surface of fracture. Color white, often yellowish or grayish.
Streak white. Subtransparent — translucent. Fracture uneven. Brittle.
H. 3-3-75. G. 4'29-4'35. Comp., carbonic acid 22'3, baryta 777.
In white masses on Cotton Creek, San Luis Park. This
mineral is poisonous.
BAR.ITE. Heavy Spar. Sulphate of Baryta.
Orthorhombic; in modified rhombic and rectangular prisms; crystals
usually tabular; also columnar, fibrous, granular and compact. Lustre
vitreous, inclining to resinous, sometimes pearly. Streak white. Color
white, yellow, gray, blue, red, brown. Transparent, translucent, opaque.
Sometimes fetid when rubbed. H. 2'5-3'5. G. 4'3-4'8. Comp., sulphuric
acid 34, baryta 66.
Of frequent occurrence in the mines, both crystallized and
massive. Extensive beds on Vasquez River. Fine single
crystals with calcite on Apishapa Creek. Beautiful clusters
of crystals in the Seven-Thirty mine, Georgetown. Barite is
used as a paint, and in adulterating white lead.
Minerals of Colorado. 39
CAL,CIXE. Calcareous Spar. Carbonate of Lime.
Rhombohedral ; occurs crystallized in upwards of 800 varieties of form.
The primary form is an obtuse rhombohedron, which may readily be ob-
tained by cleavage. Also fibrous, both coarse and fine ; sometimes lamel-
lar; often granular; also stalactitic. Lustre vitreous — subvitreous — earthy.
Color white or colorless, also various shades of red, green, gray, blue, yel-
low, violet ; brown and black when impure. Streak white or grayish.
Transparent— opaque. Double refraction strong. G 2'508-2'776. H. 2'6-
3'5. Corup., carbonic acid 44, lime 56.
Large white masses on Bear Creek, five miles above Mor-
rison, in granite. On Box Elder Creek, Laramie County, in
aggregations of crystals, and in many other localities along
the base of the mountains.
ICELAKD SPAR.
Transparent variety of calcite. Double refracting in a high degree.
Near Canon City, on Beaver Creek; on the Greenhorn and
Apishapa; in the lava of the Table Mountains, Golden.
ARGENTINE.
A foliated, white pearly calcite.
On Chalk Mountains, in veins sometimes from two to three
feet thick.
MARBLE. Granular Limestone.
Calcite having a texture like loaf sugar when broken. The texture varies
from coarse to fine granular, and the latter passes by imperceptible shades
into compact limestone. The colors are various and usually clouded.
A large vein of black white and gray marble in South
Park. Brownish-gray marble near Canon City. Hard com-
pact limestone frequently makes a fine stone when polished.
A black variety veined with white occurs on Cotton Creek,
San Luis Park. Breccia marble near Boulder. Shell marble
near Colorado Springs. Encrinal marble at Sangre de
Christo Pass.
DESCLOIZIXB.
Orthorhornbic. Lustre bright. Color black to olive-brown ; smallest
crystals olive-green, with a chatoyant bronze lustre ; by transmitted light
along the edges light brown, inclining to red; on a surface of fracture,
colors zoned with straw-yellow, reddish-brown and black; nearly clear at
middle and darkest at extremities of crystal. H. 3*5. G. 5*839. Comp.,
vanadic acid 29'3, oxyd of lead 70'7.
Sparingly in the Evening Star and other mines, Leadville.
Porcelain Clay.
Orthorhornbic; occurs in rhombic, rhomboidal, or hexagonal scales or
plates; sometimes in fan-shaped aggregations; usually constituting a clay-
like mass, either compact, friable or mealy. Lustre of plates pearly ; of
mass, pearly to dull earthy. Color white, grayish-white, yellowish, some-
times brownish, bluish or reddish. Scales flexible. Usually unctious and
plastic. H. 1-2-5. G. 2'4-2'63. Comp., silica 46, alumina 40, water 14.
Occurs as the result of the decomposition of the feldspars of
granitic rocks and porphyries throughout the state. Kaolin
is used in making porcelain and china ware.
40 Minerals of Colorado.
VESUVIA1VITE. Idocrase.
Tetragonal ; crytals usually in modified square prisms ; also found massive.
Color brown to green, the latter frequently bright and clear ; occasionally
sulphur-yellow, and also pale blue. Lustre vitreous, often inclining to
resinous. Streak white. Subtransparent to nearly opaque. H. 6'5. G.
3'34. Comp., silica 38'4, alumina 23'7, protoxyd of iron 4'0, lime 29'7,
magnesia and protoxyd of manganese 5'2.
Occurs in beautiful yellowish-green crystals on Italian Mt. ,
Gunnison County, which are said to be the finest found in the
United States. In brown crystals on Bear Creek.
AZURITE. Chessy Copper. Blue Carbonate of Copper.
Monoclinic; in modified oblique rhombic prisms, the crystals rather short
and stout; lateral cleavage perfect. Also massive, incrusting and earthy.
Lustre vitreous, almost adamantine. Color various shades of azure-blue,
passing into berlin-blue. Streak blue, lighter than the color. Transpa-
rent-subtranslucent. Fracture conchoidrl. Brittle. H. 3'5-52'5. G.
3'5-3'831. Comp., carbonic acid 25'6, oxyd of copper 69'2, water 5'2.
Occurs as on incrustation on the surface ores of many of
the mines throughout the state.
AR.SENOPYR.ITE. Mispickel. Arsenical Pyrites.
Orthorhombic ; crystallizes in right rhombic prisms, parallel to whose
planes it may be cleaved ; also occurs columnar, straight and divergent;
granular or* compact. Lustre metallic. Color silver-white, inclining to
steel-gray. Streak dark grayish-black. Fracture uneven. Brittle. H.
5-5-6. G. G'0-6-4. Comp., arsenic 46'0, sulphur 19'6, iron 44'4. Part of
the iron sometimes replaced by cobalt.
Occurs sparingly in some of the mines of Gilpin and Clear
Creek Counties.
CUPRITE. Eed Oxyd of Copper.
Isometric; in regular octahedrons and modified forms of the same. Cleav-
age octahedral. Also massive, granular ; sometimes earthy. Lustre ada-
mantine or submetallic to earthy. Color red, of various shades, particu-
larly cochineal-red ; occasionally crimson-red by transmitted light. Streak
brownish-red, shining. Subtransparent-subtranslucent. Fracture conch -
oidal, uneven. Brittle. H. 3'5-4. G. 5'85-6"15. Comp., oxygen 11"2,
copper 88*8.
In crystals, Sacramento Gulch, and in Sweet Home mine,
Buckskin. Malachite lode, Bear Creek. Massive at Poncha
Springs.
OPAL.
Massive, amorphous ; sometimes small reniform, stalictitic, or large tube-
rose. Lustre vitreous, frequently subvitreous ; often inclining to resinous,
and sometimes to pearly. Color white, yellow, red, brown, green, gray,
generally pale; sometimes a rich play of colors, or different colors by re-
fracted or reflected light. Transparent to nearly opaque. H. 5'5-6'5. G.
l'9-2:3. Comp., silica, same as quartz, with a little water.
A milk-white opal occurs in the decomposition product of
the lava on Buffalo Peaks, in the Mosquito Range. A yel-
lowish, slightly translucent opal is quite abundant six miles
south of the salt works, in South Park, associated with jasper
and chalcedony.
Minerals of Colorado. 41
FIRE OPAL.
A variety of opal presenting hyacinth-red to honey-yellow and bluish col-
ors, with fire-like reflections, somewhat irised on turning.
A bluish transparent opal, with yellowish reflections, oc-
curs in a felsitic rick near Idaho Springs, which has been
used to considerable extent in jewelry.
MYAI.1XE. Muller's Glass.
An opal usually clear as glass and colorless, constituting globular concre-
tions, and also crusts with a globular, reniforrn, botryoidal, or stalactitic
surface.
Occurs near the head of Cache la Poudre Creek, and on the
La Garita, in pearly crusts, on lava.
WOOD OPAL.
Wood petrified by opal of various shades of color.
Abundant along the sources of Cherry,. Kiowa and Bijou
Creeks, at Happy Canon, and in Middle Park, much of which
is agate-like in structure, and of a diversity of colors.
BKRAL.
Hexagonal ; usually in long, stout six-sided prisms, without regular ter-
minations; occasionally coarse columnar. Lustre vitreous, sometimes res-
inous. Color bright green (when it is known as emerald], pale green, pass-
ing into light blue (aquamarine], yellow and white. Transparent-subtrans-
lucent. H. 7'5-8. G. 2'63-2 76. Comp., silica 66'8, alumina 19'1, glu-
cina 14'1.
Beryls of enormous size, but nearly opaque and of inferior
color, in white quartz, on Bear Creek. Small crystals of light
green color in the Floyd Hill region; also on the Platte River,
at the edge of South Park. Colorless and light green trans-
parent crystals on Mt. Antero, Chaffee County.
AQUAMARINE.
Beryls of a sea-green or pale bluish-green tint.
Beautiful transparent crystals, of bluish-green color, occur
on Mt. Antero, ChafFee County. Rarely on Bear Creek.
GOXMITE. Brown Iron-Stone
Orthorhombic; in prisms longitudinally striated, and often flattened into
scales or tables parallel to the shorter diagonal. Cleavage very perfect.
Also fibrous, foliated, in scales, massive, stalactitic. Lustre imperfect ad-
amantine. Color yellowish, reddish, and blackish brown. Often blood-
red by transmitted light. Streak browish-yellow, ochre-yellow. H. 5-5'5.
G. 4'6-4 4 Comp., sesquioxyd of iron 89'9, water lO'l.
Abundant in the Pike's Peak region, in cavities in granite,
associated with amazonstone, smoky quartz, fluor spar, etc.
BASTNASITE. Allen & Comstock, Am. Jr. Sc., May, 1880.
Hexagonal ; occurs in six-sided prisms. Color reddish-brown. Lustre
vitreous to resinous. H. 4-4'5. G. 5'18-5'20. Analysis of Colorado min-
eral by Allen & Comstock : oxide of cerium 40'88, oxide of lanthanum
and didymium 34'95, carbonic acid 20'09, fluorine (by difference) 4'08.
Occurs as an alteration product of tysonite west of Chey-
enne Mountain, El Paso County.
42 Minerals of Colorado.
PTII^OUTE. (new.) W. Cross, Am. Jr. Sc., Aug., 1886.
Occurs in white tufts of short hair-like needles. Analysis by Eakins : sil-
ica 70-35, alumina 1T90, lime 3'87, potassa 2'83, soda 0'77, water 10'16.
Occurs as tufts of short hair-like needles in augite-andesite.
on the north slope of Green Mountain, Jefferson County.
ARAQOXITB.
Orthorhombic ; primary form a right rhombic prism ; occurs in hexagonal
prisms, very frequently in twin crystals, also in globular, reniform, den-
dritic, and coralloidal shapes; sometimes fibrous and in compact masses.
Color generally white, but sometimes tinged yellow, blue and green. Lus-
tre vitreous, inclining to resinous on fractured surfaces. Translucent to
transparent. Fracture subconchoidal. H. 3'5-4. G. 2'031. Cornp., car-
bonic acid 44, lime 56.
Coralloidal and in small masses in a number of lodes on
L,eavenworth Mountain, Georgetown. Near Golden. One
mile below Idaho Springs is a variety very similar to the cel-
ebrated gibralter rock, of Spain. In South Park, two
miles south-west of the Salt Works, in coarsely radiated and
columnar masses. On Willow Creek, San Luis Valley, a
vein about 30 feet wide, in basalt, portions of which exhibit
a botryoidal structure. Coralloidal at Loma. Six miles be-
low Del Norte, on the Rio Grande, a large deposit.
Chlorobromid of Silver.
Isometric; occurs in cubes and cubo-octahedrons ; also massive, sometimes
stalactitic. Lustre resinous and somewhat adamantine. Color grayish-
green and asparagus-green to pistachio or yellowish-green, and yellow,
often dark ; becoming darker externally on exposure. H. 1-1'5. G. 5*31-
5*43. Comp., varies, silver 61 to 71, bromine 7 to 33, chlorine 5 to 20.
Sparingly in the mines of L/eadville.
XYSONITE. (new.) Am. Jr. Sc., May, 1880, June, 1884.
Hexagonal; occurs in prisms with basal cleavage. Color pale wax-yellow.
Streak nearly white. Lustre vitreous to resinous. H. 4'5-5. G. 6'14.
Analysis by Allen & Com stock : cerium 40'16, lanthanum and didymium
30-29, fluorine 29'55.
Occurs near Pike's Peak, associated with bastnasite, both
minerals being frequently found in the same crystal, the cen-
tral portion of the crystal being composed of tysonite. Spec-
imens have been found weighing several pounds. Named
after S. T. Tyson, a metallurgist of Colorado.
PYR.IXE. Iron Pyrites. Bisulphuret of Iron.
Isometric; occurs in cubes, simple and modified; pentagonal dodecahe-
drons and octahedrons; crystals frequently forming aggregations; also
massive and in imitative shapes. Color bronze-yellow. Lustre metallic,
splendent. Brittle. H. 6-6'5. G.4'8-5'1. Comp., iron 467, sulphur 53'3.
Abundant in many of the mines, and usually valuable for
the gold and silver it contains. Beautiful cubical crystals in
the mines of Gilpin County. Dodecahedrons and cubo-octa-
hedrons in the Josephine mine, Geneva District, Clear Creek
County.
Minerals of Colorado. 43
Rhombohedral ; usually in prisms terminating in a low pyramid ; cn-stals
usually hemihedral, being often unlike at the opposite extremities, or
hemimorphic, and the prisms often triangular. Sometimes massive com-
pact ; also columnar, coarse or fine, parallel or divergent. Lustre vitreous.
Color black, brownish-black, bluish-black, most common ; blue, green, red,
and sometimes of rich shades; rarely white or colorless ; some specimens
red internally and green externally ; and others red at one extremity, and
green, blue, or black at the other. Dichroic. Transparent — opaque. Py-
roelectric. Brittle. H. 7-7'b. G. 2'94-3'3. Comp., black variety, silica
33, alumina 38, lime 1 protoxyd of iron 24, soda 3, boracic acid 1.
Fine black triangular prisms, with pyramidal terminations,
on Bear Creek, imbedded in white quartz. On Clear Creek,
two miles below black Hawk, hexagonal prisms in feldspar.
At Guy Hill. Five miles north of the Platte, on the road
from Colorado Springs to Fairplay, fine crystals with termin-
ations.
PETZITE. Tell u ride of Gold and Silver.
Orthorhombic. Massive; compact or fine-grained ; rarely coarse-granu-
lar. Lustre metallic. Color between steel-gray and iron-black, sometimes
with pavonine tarnish. Streak iron-black. Brittle. H. 2'5. G. 8'72-
8'83. Comp., tellurium 35, silver 47, gold 18.
In Boulder County, associated with other tellurium ores.
Orthorhombic; occurs in short tabular, six-sided prisms, with the bases
triangularly striated parallel to alternate edges. Cleavage basal, imper-
fect. Also massive and disseminated. Lustre metallic. Color iron-black;
in thin crystals cherry-red by transmitted light. Streak iron-black. Frac-
ture uneven. H. 2-3. G. 6'214. Analysis of polybasite from Terrible
mine, Georgetown, by Dr. Genth : sulphur 16'70, antimony 10'18, arsenic
0'78, silver 02'70, copper 9'57, iron 0 97.
In small quantity in many of the silver mines. Fine crys-
tals in the Little Emma and Colorado Central mines, George-
town.
TEXRAHEDRIXE. Gray Copper. Freibergite. Fahlerz.
Isometric; tetrahedral; occurs crystallized in modified tetrahedrons, and
also in compound crystals; also massive; granular, coarse or fine. Lustre
metallic. Color between light flint-gray and iron-black. Streak generally
same as the color: sometimes inclining to brown and cherry-red. Opaque;
sometimes subtranslucent in very thin splinters, transmitted color cherry-
red. Fracture subconchoidal — uneven. Rather brittle. H. 3-4'5. G. 4'5,
5'11. Comp., varies; freiberyite, the argentiferous variety, sulphur 21 to 30,
antimony 17 to 28, copper 14 to 36, iron 1 to 7, zinc 1 to 6, silver 3 to 31.
Largely disseminated through nearly all sulphide silver
ores in the state. That from the mines about Georgetown
carries from 20 to 30 per cent of silver, while that from con-
tiguous districts, 3 or 4 miles from Georgetown, carries only
i or 2 per cent of silver. Good crystals, having pavonine
tints, in the Champion lode, Geneva District, Clear Creek
County.
44 Minerals of Colorado.
Chalybite. Spathic Iron. Carbonate of Iron.
Bhombohedral ; occurs in obtuse rhombohedrons, whose faces are often
curved, in acute rhombohedrons, sometimes perfect, or having the terminal
angles replaced, and in lenticular crystals; also in botryoidal and globular
forms, subfi brous within, occasionally silky fibrous ; often cleavable mass-
ive, with cleavage planes undulating ; coarse or fine granular. Lustre vit-
reous, more or less pearly. Color ash-gray, yellowish-gray, greenish-gray,
also brown and brownish-red, rarely green, and sometimes white. Streak
white. Translucent — subtranslucent. Fracture uneven. Brittle. H. 3'5-
4'5. G. 3'7-3'6. Comp., carbonic acid 37'9, protoxyd of iron 62'1.
Of frequent occurrence in the mines, both massive and crys-
tallized.
CYAXIfE.
Triclinic; usually in long-thin-bladed crystals aggregated together, or pen-
etrating the gangue; crystals sometimes short and stout. Lateral cleav-
age distinct. Sometimes fine fibrous. Lustre vitreous — pearly. Color
blue, white, blue along the center of the blades with white margins; also
gray, green, black. Streak uncolored. Translucent — transparent. H. 5-.7
G. 3'6-3'7. Comp., silica 37, alumina 63.
Occurs in the quartzite of Medicine Bow Peak.
TBTRAOYMIXE. Telluric Bismuth.
Hexagonal ; crystals often tabular. Cleavage basal, very perfect. Also
massive, foliated or granular. Lustre metallic, splendent. Color pale
steel-gray. Laminae flexible. Soils paper. H. l'5-2. G. 7'2-7'9. Comp ,
tellurium 48, bismuth 52.
At Gold Hill, Boulder County, associated with other tel-
lurium ores.
Phosphate of Yttria. W. E. Hidden, Am.Jr.Sc., March,IS8a.
Tetragonal ; primary form a rectangular prism with a square base ; occurs
in square octahedrons, with perfect prismatic cleavage. Color yellowish-
brown, reddish-brown, hair-brown, flesh-red, grayish-white, pale yellow.
Streak pale brown, yellowish or reddish. Opaque. Fracture uneven and
splintery. H. 4-5. G. 4'45-4'56. Comp., phosphoric acid 37'86, yttria
62-14. "
Small chocolate-brown crystals west of Cheyenne Mountain,
El Paso County, from same locality as tysonite and bastnasite.
TORBERNI'TE. Copper-Uranite.
Tetragonal ; in square tables, often with replaced edges. Cleavage basal,
highly perfect, micaceous. Lustre pearly — adamantine. Color emerald-
and grass-green, and sometimes leek-, apple- and siskin-green. Streak
somewhat paler than the color. Transparent — subtranslucent. Sectile.
Laminae brittle and not flexible. H. 2-2'5. G. 3'4-3'6. Comp., phospho-
ric acid 15'7, oxyd of uranium 62'7, lime 6'1, water 15'5.
Sparingly in the Peabody lode, Georgetown.
BROMYRIXB. Bromic Silver. Bromid of Silver.
Isometric ; occurs in cubes, octahedrons and cu bo-octahedrons ; but gen-
erally in small concretions. Lustre splendent. Color when pure, bright
yellow to amber colored, slightly greenish ; often grass-green or olive-
green externally. Sectile. H. 2-3. G. 5'8-6. Comp., bromine 42'6,
silver 57*4.
Occasionally found in the mines at L/eadville.
Minerals of Colorado. 45
COAL.
The distinguishing characters of mineral coal are as follows : Compact
massive, without crystalline structure or cleavage; sometimes breaking
with a degree of regularity, but from a jointed rather than a cleavage
structure. Sometimes laminated ; often faintly and delicately banded, suc-
cessive layers differing slightly in lustre. Lustre dull to brilliant, and
either earthy, resinous or submetallic. Color black, grayish-black, brown-
ish-black, and occasionally iridescent; sometimes dark brown. Opaque.
Fracture conchoidal — uneven. Brittle; rarely somewhat sectile. Infus-
ible to subfusible; but often becoming a soft, pliant, or paste-like mass
when heated. On distillation most kinds afford more or less of oily and
tarry substances, which are mixtures of hydrocarbons and paraffin. Hard-
ness" 0-5—2-5. Gravity 1— 1'80.
The varieties depend partly (i) on the amount of the vol-
atile ingredients afforded on destructive distillation; or (2) on
the nature of these volatile compounds, for ingredients of sim-
ilar composition may differ widely in volatility; (3) struct-
ure, lustre, and other physical characters. The following
varieties are found in Colorado:
BR.OWIV COAL. Lignite.
Sometimes pitch-Mack, but often rather dull and brownish-black. Fragile
compared with anthracite. Occasionally somewhat lamellar in structure.
The lignite coal area of Colorado extends from St. Vrains
on the north to the Raton Mountains on the south, about 220
miles in length, and varying from 20 to 35 miles in breadth
along the eastern base of the mountains. Large portions of
this field have been swept away by floods resulting from melt-
ing glaciers. The principal developments of this vast field
have been made in the vicinity of Boulder, Erie, L/oveland,
Golden, Colorado Springs, Coal Creek, Canon City, Walsen-
burg and Trinidad. Lignite also exists in North Park and
at various points on the divide between North and Middle
Parks. The following analyses have been made:
Water. Volatile Fixed Ash. Sul-
Matter. Carbon. phur.
Coal Hill, North Park 18'35 32'20 41'90 6'45 1.10
do do 8-82 41-56 4M7 6'00 2'45
Red Hill, do 15'20 3330 48'00 3'50
do do 10-50 37-30 50'30 1'90
No. 1, do 13-20 9-30 72-00 5'50
Erie Mine. Weld County 14'80 34'50 47'30 3'40
Marshal Mine, Boulder County .- 1200 26'00 59'20 2'80
Murphy Mine, Jefferson County 13'83 35'88 44'40 5'85
Golden, do do " 13'43 37'15 45'57 3'85
Franceville, El Paso County.... 12'90 . 29'10 46'00 12'00
Cutler banks, Uncompahgre County ... 7'26 43*42 41'72 7'60
JET.
Jet is a black variety of brown coal, compact in texture, and taking a good
polish, whence its use in jewelry.
Occurs in seams, from one-half to six inches in width, in
the shale about Canon Citv and Little Fountain Creek.
46 Minerals of Colorado.
BIXUIJ11XOIJS COAI,.
Bituminous coals have the common characteristic of burning in the fire
with a yellow, smoky flame, and giving out on distillation hydrocarbon
oils or tar. They have usually a bright, pitchy, greasy lustre. The cak-
ing variety becomes pasty or semi-viscid in the fire. The softening takes
place at the temperature of incipient decomposition, and is attended with
the escape of bubbles of gas. On increasing the heat, the volatile products
which result from the ultimate decomposition of the softened mass are
driven off, and a coherent, grayish-black, cellular, or fritted mass (coke) is
left. A caking coal will lose its caking quality if kept heated for 2 or 3
hours at 300°C., and sometimes on mere exposure for a time to the air.
Non-caking coal is like the preceding in all external characters, and often
in ultimate composition ; but burning freely without softening. The coke
is not a proper coke, being in powder, or of the form of the original coal.
The Trinidad group of mines, embracing those in the im-
mediate vicinity of Trinidad with those of ElMoro and Stark-
ville, and the mines at Crested Butte, are the most important
of this class in the State. Durango, Aspen and Rico are
other localities of its occurrence.
Water. Volatile Fixed
Matter. Carbon.
•95 29'82 56'41
Ash.
12-82
4-32
6-30
4-47
3-09
... '26 29'66 65'76
.... 3'23 40'93 49-54
.... 3'70 30'97 61'07
, -44 24-17 72-30
SEMI- BITUMINOUS.
Col. Coal and Iron Co., Park County 5'03 35'85 50'97 8'15
Oak Creek, do 672 3476 5270 5'82
Semi-bituminous coal is found principally in the mountain-
ous part of the state, The mines at Como on the South Park
railway are the most productive of this class. A good vein
has also been opened up on Mt. Carbon, 17 miles north-west
of Gunnison City. The coal from Walsenburg is by many
regarded as belonging to this class.
Color jet-black ; vandyke-brown when powdered. Has the appearance of
bituminous coal. Does not slack or break to pieces. In composition
much like albertite and torbanite. G. 1'323. Analysis by E. J. Mallett:
Water 6'02
Volatile matter 39'95
Fixed carbon and ash 54'03— lOO'OO
The locality of this new coal species is Middle Park. It is
a caking bituminous coal but yields an imperfect coke. In
comparison with English cannel coal it gives thirty per cent
more gas of a high illuminating power. It is named after
Mr. W. N. Byers.
NATIVE COKE.
More compact than artificial coke, and sometimes affording considerable
bitumen.
The origin of native coke is attributed to the action of a
Minerals of Colorado. 4j
trap eruption on bituminous coal. It has been found near
Crested Butte where a dike of lava has intruded the coal
strata. It has also been found at Trinidad.
ANTHRACITE;.
Lustre bright, often submetallic, iron-black, and frequently iridescent.
Fracture conchoidal. Volatile matter afttr drying 3 to 6 per cent. Burns
with a feeble flame of a pale color. H. 2-2'5.
Anthracite coal appears to be confined mainly to the coal
basins in the Elk Mountains, and extends over a large scope
of country. These mountains are composed of lofty peaks of
eruptive rock, and are separated from the plains by three par-
allel ranges, the Colorado or Front Range, the Park Range
and the Saguache Range, separated from one another by
trough-like valleys and parks. The coal fields are in the
same geological horizon as that of the plains, and the coal
is much the same, metamorphosed or changed by heat into
anthracite, and on the outer edges of the basins graduates
into lignite. On Anthracite Mesa, near Crested Butte, the
veins are from two to ten feet thick. Analyses show
Water. Volatile Fixed Ash.
Matter. Carbon.
Crested Butte, Gunnison County ....................... T20 5'16 90*24 3'40
Anthracite Creek, do ....................... 2'00 2'50 9190 3'60
Anthracite Mesa, do ....................... 5'17 90'85 4'18
Rock Creek, do ....................... 7'40 88'90 3'68
SEMI-ANTHRACITE.
W. & D. Trust Co., Crested Butte ..................... 4'00 14'00 74'00 8'00
Uncompahgre Canon ..................................... 1/86 10'70 77'32 1012
PETRO1LBUM. Naptha. Mineral Oil. Kerosene.
A fluid bitumen of dark color, which oozes from certain rocks and becomes
solid on exposure, forming asphaltum. Com., carbon 82'2, hydrogen 14'8.
Oozes from sandstone near Morrison. Six oil wells are in
operation in the neighborhood of Canon City and Florence, in
Fremont county. The Oil Creek well, which was sunk in
1862, turned out about 3,000 gallons of oil.
ASPHAI/TUM. Bitumen. Mineral Pitch.
Amorphous. Lustre like that of black pitch. Color brownish-black and
black. Odor bituminous. Melts ordinarily at 90° to 100° C., and burns
with a bright flame. Soluble mostly or wholly in oil of turpentine, and
partly or wholly in ether; commonly partly in alcohol. The more solid
kinds gradate into the pittasphalts or mineral tar, and through these is a
gradation to petroleum. Comp., carbon 75'0, hydrogen 9'5, oxygen 15'5.
Fluid bitumen oozes from sandstone near Morrison and
forms an earthy asphaltum. In the White River region and
near Canon Cit.
RKSIN.
• Mineral resin occurs Jin the coal in scales, and small masses
have been found in the soil on the Table Mountains, but the
48 Minerals of Colorado.
species have not been determined. Prof. Wm. P. Headden
mentions the occurrence of a substance in coal from the
Mitchell mine, Brie, which he believes to be napthaline. It
occurs in microscopic, tabular crystals, which are thin, color-
less and transparent.
TURGIXB.
Compact fibrous and divergent, to massive; often botryoidal and stalactitic
like limonite. Also earthy, as red ochre. Lustre submetallic and some-
what satin-like in the direction of the fibrous structure; also dull earthy.
Color reddish-black, to dark red ; bright-red when earthy ; botryoidal sur-
face often lustrous, like much limonite. Opaque. H" 5-6. G. S'56-3'74.
Comp., Sesquioxyd of iron 94*7. water 5'3.
Occurs in small botryoidal masses, of reddish-black color,
and highly polished surfaces, at Florissant, associated with
gothite, amazonstone, smoky quartz, etc.
Iron-Alumina Garnet. Precious or Oriental Garnet.
Isometric; occurs in dodecahedrons and trapezohedrons, both forms some-
times variously modified ; rarely in octahedrons. Cleavage parallel to
the faces of the dodecahedron. Also found massive. Color fine deep-red
and transparent, and then ealled precious garnet; also brownish-red, and
translucent or subtranslucent. Streak white. Lustre vitreous — resinous.
Fracture subconchoidal, uneven. H. 6'5-7"5. G. 4'13. Comp., silica 36'1,
alumina 20*6, protoxyd of iron 43 '3.
L/arge and perfect dodecahedrons, some of them measuring
six inches in diameter, occur in chlorite near Salida, Chaffee
County. Several thousand specimens have been taken out
of a single "pocket." They are usually coated with chlorite,
and the surfaces of the garnets are decomposed, the decempo-
sition product forming aphrosiderite. The color of the garnet
is brownish-red. Analysis by S. L. Penfield and F. L/. Sperry
gave the following:
Silica ...................................... 37-61
Alumina ................................. 2270
Protoxyd of Iron ...................... 33'83
Protoxyd of Manganese .............. 1*12
Magnesia ................................. 3'61
Lime ...................................... 1'44
100-31
Beautiful dark red garnets, which can probably be classed
as precious garnets, are abundant in the placers at Fairplay
and Breckenridge. The are usually quite small and of no
value as gems.
APHROSIDBRITE.
A soft ferruginous chlorite, of a dark olive-green color, scaly massive in
structure ; the scales minute, transparent, and hexagonal.
Occurs as an alteration product on the garnets found at Sa-
lida, forming a coating- of light green color. Analysis by
Penfield and Sperry gave:
Minerals of Colorado. 49
Silica ...................................... 28-20
Alumina ................................. 22'31
Protoxydof Iron ....................... 19'11
Protoxyd of Manganese .............. 17*68
Lime ..................................... '48
Soda ...................................... 72
Potassa ............... .. ................... 1'03
Water .................................... 10'90
FAYAI^IXB. Iron Chrysolite. Anhydrous Silicate of Iron.
Massive, crystalline. Cleavage in two directions at right angles to one
another. Lustre metalloid, somewhat resinous in the fracture. Color
black ; sometimes iridescent. Opaque. Fracture imperfectly conchoidal.
Attractable by the magnet. H. 6'5. G. 4-414. Com p., silica 29'5, pro-
toxyd of iron 70'5.
Occurs in quite large masses in Cheyenne Canon, El Paso
County.
FIRROWTK.
Monoclinic ; crystals commonly long and slender. Cleavage brilliant and
perfect. Also occurs fibrous or columnar massive, sometimes radiating.
Lustre vitreous, subadamantine. Color hair-brown, grayish-brown, gray-
ish-white, grayish-green, pale olive-green. Streak uncolored. H. 6-7.
G. 3-2. Comp., silica 36'8, alumina 63'2.
Occurs in small fibrous masses, of grayish-green color, on
Sherman Mountain, near Georgetown.
SAXIDIK. Glassy Feldspar. Whitman Cross, Am. Jr. Sc., Feb., 1884.
A variety of orthoclase (p.12) occurring in transparent glassy crystals,
mostly tabulur, in eruptive rock.
Mr. Cross describes the occurrence of sanidin in the nevad-
ite of Chalk Mountain, and rhyolite of Ragged Mountain,
which possesses a satin lustre. Smoky quartz and topaz are
associates of the sanidin in the nevadite. Also occurs in rhy-
olite at Nathrop, with the same associate minerals.
Pearl Spar. Brown Spar. Magnesian Limestone.
Rhombohedral ; crystals often having curved faces. Cleavage perfect
parallel to the primary faces. Often granular and massive, constituting
extensive beds. Color white or tinged with yellow, red, green, brown and
sometimes black. Lustre vitreous or a little pearly. Nearly transparent
to translucent. Brittle. H. 3'5-4. G. 2'8-2'9. Comp., carbonate of lime
54'35, carbonate of magnesia 45'65.
Occurs in extensive beds in various portions of the State,
and in small quantities in the mines, frequently crystallized.
Acanthite, 13
Bismuthinite, 9
Chrysolite, 37
Actinolite, 30
Bismutite, 35
Citrine, 24
Agate, 18
Bitumen, 47
Cobalt, Arsenate, 30
Agatized Wood, 18
Bituminous Coal, 46
Arsenide, 8
Alabaster, 26
.B/ac& Tellurium, 38
Iftoom, 30
Alabandite, 35
Black Lead, 27
Columbite, 19
Alaskaite, 8.
Blende, 25
Coloradoite, 31
Allanite, 21
Bloodstone, 17
Common Mica, 35
Alamandite, 48
.B/we Carbonate Copper, 40
Common Salt. 25
yl/oite, 12
£ke yftno/, 31
Copper, Carbonate, 36, 40
Allophane, 21
tfo/e, 17
O/ance, 37
^4/toite, 21
Bornite, 14
Native, 6
vlfotra, Native, 23
Bromyrite, 44
Oxide, 40
Amazonstone, 12
Brochantite, 10
Pyrites, 9
Amethyst, 23
Bromid of Silver, 44
SiJieate, 29
Amphibole, 30
Bromic Silver, 44
Sulphate, 10, 31
Analcite, 15
Brown Coal, 45
Sulphide, 37
Anglesite, 7
Brown Iron Ore, 41
Uranite, 44
Annabergite, 37
Brown Ochre, 33
CosaMe, 13
Anthracite, 47
Brown Spar, 49
Covellite, 19
Antimony Glance, 23
Byerite, 46
Cryolite, 11
Aphrosiderite, 48
Cuprite, 40
Apophyllite, 15
Aquamarine, 41
Cairngorm, 24
Cyanite, 44
Aragonite, 42
Arfvedsonite, 22
Argentite, 13
Argentine, 39
Arsenide of Cobalt, 8
Calaverite, 29
Ca/ctte, 39
Calcareous Spar, 39
Carnelian, 17
Carbonate Bismuth, 35
7)ar^ fled StVwer Ore, 19
Dechenite, 38
Desdoizite, 39
Dolomite, 49
J.T01l>) u
Arsenopyrite, 40
Arsenical Pyrites, 40
Ar senate of Nickel, 37
Arsenical Nickel, 7
Asbestus, 30
Asphaltum, 47
Astrophyllite, 32
Autunite, 13
Soda, 34
7ron, 44
Baryta, 38
Copper, 40
Lead, 36
Manganese, 10
Gassiterite, 21
G&sfo'te, 25
Egyptian Jasper, 24
Elpasolite, 20
Embolite, 42
Enargite, 13
Epid'ote, 36
Erythrite, 30
Erubescite, 14
J5<ye ,4 pate, 18
^iiZttTitC) 40
Cerargyrite, 24
FaMerz, 43
Cerussite, 36
Fa/se Topaz, 24
Banded Agate, IS
Chabazite, 14
Fayalite, 49
Barite, 38
Chalcanthite, 31
Feldspar, 12
Bastnasite, 41
Chalcedony, 14
FtrroteUurite, 29
Beegerite, 8
Chalcocite, 37
Fibrolite, 49
Beryl, 41
Chalcopyrite, 9
Fibrous Gypsum., 26
Biotite, 35
Bismuth, Carbonate, 35
Glance, 9
Chalybite, 44
CAes.st/ Copper, 40
CMort'd o/ /Si/twr, 24
Fibrous Heavy Spar, 25
I' ire OpaZ, 41
Fluorite, Fluor Spar, 10
Native, 6
Sodium, 25
Foliated Tellurium, 38
S/foer, 32
Chrysocolla, 29
Fortification Agate, 18
Sulphide, 9
Vhn/soprase 18
Freibergite, 43
INDEX.
Gadolinite, 26
Levynite, 16
Nickel Green, 37
Gahnite, 22
Lt<7/&< JFfat&y Silver Ore, 1 9
OcAre, 37
Galenite, Galena, 38
Lignite, 45
Telluride, 7
Garnet, 33
Lime Uranite, 13
Niccolite, 7
Gearksutite, 11
Limonite, 33
Glassy Feldspar, 49
GWd, 5
Lionite, 29
Lollingite, 9
Oblique Mica, 35
Octahedral Iron Ore, 34
Gothite, 41
Oiivene, 37
Graphite, 27
Graphic Tellurium, 32
Crrai/ Copper, 43
Green Carbonate Copper, 36
#reen Lead Ore, 37
Magnetite, 34
Malachite, 36
Manganese, Carbonate, 10
6?ame«, 36
Sulphate, 31
Ora/z, 18
OpaZ, 40
Oriental Garnet, 48
Orthodase, 12
Guitermanite, 9
Gypsum, 26
ITaftte, 25
Heavy Spar, 38
Heliotrope, 17
Hematite, 34
Hessite, 28
Sulphide, 35
Magnesian Limestone, 49
Magnetic Iron Ore, 34
Magnesia Mica, 35
Magnesia Alum, 23
Magnolite, 29
JfairWe, 39
Melonite, 7
Pachnolite, 11
Pear/ Spar, 49
Peridot, 37
Petroleum. 47
Peteite, 43
Phenacite, 7
Phosphate of Lead, 37
TT-, , • ,« *
Hexagonal Mica, 35
Hornblende, 30
LTorn Silver, 24
Hubnerite, 17
Hyalite, 41
Mendozite, 31
Mesolite, 16
Mercury, Native, 5
Telluric, 44
Telluride, 29, 31
Micaceous Iron 34
Yttna, 44
Pickeringite, 20
Pitchblende, 28
Pitchstone, 12
Plumbago, 27
Polybasite, 43
Iceland Spar, 39
Idocrase, 40
Ilesite 31
Microclin, 12
Mineral Coal, 45
Oi/. 47
Porcelain Clay, 39
PofasA ,4/?/m,'28
Potas/t Feldspar, 12
/ran, Arsenide, 9
Arsenical, 40
Carbonate, 44
Chrosolite, 49
Columbate, 19
<?ame«, 48
Oxide, 33, 34, 41, 48
Pyrites, 42
Silicate, 49
Sulphate, 7
Sulphide, 42
PiteA, 47
Resin. 47
Mispickel, 40
J/ocAa Stone, 18
Molybdenite, 25
.Moss ^4<7a<e, 18
Morion, 24
Mutter's Glass, 41
Muriate of Soda, 25
Muscovite, 35
Potash Mica, 35
Prase, 18
Precious Garnet, 48
Prosopite, 11
Proustite, 19
Protoxyd of Uranium, 28
Ptilolite, 42
Purple Copper Ore, 14
Pyrargyrite, 19
Pyromorphite, 37
Pyrite, 42
Nagyagite, 38
Jarosite, 7
Naptha, 47
Qwarte, 23
Jasper, 24
Natrolitc. 16
Quicksilver, 5
Jet, 45
Natron, 34
Native Alum, 23
Radiated Zeolite, 14
Kalinite, 23
Bismuth, 6
Rcdstonite, 19
Kaolinite, 39
(Me, 46
.Red Oo6a/« Ore, 30
Kerosene, 47
Copper, 6
^ed OcAre, 34
Kobellite, 27
6rO/d, 5
.Red Oxide o/ Copper, 40
Mercury, 5
^ed ASi/uer Ore, 19
Laumonite, 15
Silver, 5
Rhodochrosite, 10
Lead, Carbonate, 36
Sulphur, 6
Ribbon Jasper, 24
Phosphate, 36
Tellurium, <>
JRoefc Crystal, 23
Sulphate, 7
iVeed/e Zeofo'fe, 16
Rock Salt, 25
Sulphide, 38
Telluride, 21, 38
Nephelite, 37
Nickel, Arsenate, 37
Roscoelite, 27
• ^ose Quartz, 24
Vanad,ate, 38, 39
Arsenical, 7
Kw6t/ Sifoer Ore, 19
INDEX.
Sanidin, 49
Sulphate of Lime, 26
Tourmaline, 43
Salt, 25
Manganese, 31
Tremolite. 30
Sardonyx, 18
Strontia, 25
Tysonite, 42
Satin Spar, 26
Sulphide of Antimony, 23
Tungstate of Lime, 27
Schedite, 27
Bismuth, 7
Magnesia, 17
Schirmerite, 32
Copper, 19
Manganese, 28
Scolecite, 16
/row, 42
Z\*r$r;te, 48
£e/enite, 26
£ead, 38
Siderite, 44
Siftcafe o/ Iron, 49
Manganese, 35
Molybdena, 25
Uraninite, 28
Silver, Chloride, 24
Chloro- Bromide, 42
tfiteer, 13,
Zirac, 25
Vesuvianite, 40
Bismuth, 32
Sulphur, Native, 6
FV^-eows Copper Ore, 37
£M?, 14
Sylvanite, 32
Volcanic, Glass, 12
Bromic, 44
frlnnrc 1 '•?
\jriUjliLti, -LO
Native, 5
Telluric Bismuth, 44
tfito'te iea^ Ore, 36
Sulphide, 13
Telluride, 29, 32
Smaltite, 8
Smoky Quartz, 24
Teilurious Acid, 29
Telluride of Gold, 29
. £ead,21
Mercury, 29,31
Willemite, 31
Witherite, 38
Wolframite, 28
Food OpaJ 41
/Soda J.^m, 31
Mdfce/, 7
Specular Iron, 34
Tellurite. 29
Xenotime, 44
Spessartite, 36
Tellurium, Native, 6, 29
Spathic Iron, 44
Sphalerite, 25
Sphene, 37
Stibnile, 23
,»ite, 14
Tennantite, 8
Tetradymite, 44
Tetrahedrite 43
Thomsenolite, 1 1
Thomsonite, 15
Zinc Blende, 25
Silicate, 27, 31
Spme/, 22
Sulphide, 25
Sulphate of Baryta, 38
Copper, 31
/row, 7
Tm ^tone, 21
Titanite, 37
Topaz, 22
Zinkenite, 8
Zircon, 2C
Zunyite, 12 '
Lmd, 7
Torbernite, 44
E3VSTATITE. Bronzite. Protobastite. W. Cross, Bulletin No. 1, U. S.
Geological Survey.
Orthorhombic; primary form an oblique four-sided prism with a very dis-
tinct cleavage parallel to the lateral planes; sometimes a fibrous appear-
ance on the cleavage surface; also occurs massive and lamellar. Lustre a
little pearly on the cleavage-surfaces to vitreous; often metalloidal in the
"bronzite variety. Color grayish-white, yellowish-white, greenish-whits, to
olive-green and brown. Streak uncolored, grayish. Double refraction
positive. H. 5'5. G. 31 — 3'3. Composition :
Silica .................................... 60
Magnesia .............................. 40
Sometimes iron, alumina, etc. -
100
Whitman Cross gives the occurrence of an enstatite-bearing
diabase in a narrow dike of dark rock at Morrison.
Iron Potash Mica.
Hexagonal ; occurs in small six-sided tables, or an aggregation of minute
opaque scales, with perfect basal cleavage. Lustre adamantine, inclining
to vitreous, pearly. Color black with occasionally a leek-green reflection.
Streak grayish-green. Opaque or translucent in very thin laminae. Some-
what brittle, or but little elastic. H. 3. G. 3. Composition :
Silica ................................ 37-40
Alumina ........................... 1T60
Peroxide of Iron ................. 27'66
Protoxide of Iron ................. 12'43
Magnesia .......................... 0'26
Potash ............................. 9-20
Water ................................ 0'60
99-69
According to Hague, some of the mica in the granite of the
eastern Colorado range is lepidomelane.
Manganese Spar, Bisilicate of Manganese.
Triclinic, and like pyroxene, with a cleavage in three directions, two of
which are perpendicular to each other. Usually massive. Lustre vitre-
ous. Color light brownish-red, flesh-red, sometimes greenish or yellowish,
when impure ; often black outside from exposure. Streak white. Trans-
parent — opaque. Fracture conchoidal — uneven. ^Very tough when mas-
sive. H. 5-5— 6-5. G.3'4— 3-ti8 Composition:
Silica . ................................ 45-9
Protoxide of Manganese ......... 51*4
lOO'O
Occurs as a gangue of light rose color in the San Juan mines.
56 APPENDIX.
ALAMANDITE (p. 48). — New localities in Chaffee County
mentioned by W. B. Smith. Dodecahedral crystals in chlo-
ritic schist from Longfellow gulch. Crystals in limestone,
having the dodecahedron and trapezohedron about equally
developed, from Calumet.
CINNABAR is said to be found near Durango, but needs
verification.
BNARGITE (p. 13). — Occurs massive and in slender crystals
in the Missouri mine, Hall Valley, Park County. Small
masses in the Centennial mine, Georgetown. In considerable
quantity in the Forest Queen mine, Gunnison County, and in
the mines of Red Mountain district, San Juan.
GRAPHITE (p. 27). — A large deposit a few miles south of
the El Moro coal banks, Las An i mas County.
NATIVE SULPHUR (p. 6). — Abundant in the Spirit mine at
Red Cliff.
PETROLEUM (p. 47). — Has been found on Green River.
TENNANTITE (p. 8). — In large quantities in the Red Moun-
tain mines, San Juan.
TORBERNITE (p. 44).— Occurs on Lyden Creek (Berthoud),
Oxide of Lead.
Occurs pulverulent, occasionally exhibiting, under the microscope, cryw-
talline scales. Lustre faint greasy, or dull. Color vivid red, mixed with
yellow. Streak orange-yellow. Opaque. H. 2 — 3. G 4'6. Composition;
Oxygen .............................. 9'34
Lead ............................. ..... 90'66
100-00
Prof. Emmons mentions its occurrence in some of the mines
at Leadville.
Monoclinic ; primary form a right rhombic prism. Occurs in attached
crystals and in layers and granular masses, frequently in a globular form.
Lustre vitreous; pearly on planes of cleavage. Color various shades of
white, passing into red, gray and brown. Streak white. Transparent —
subtranslucent. Fracture subconchoidal, uneven. Brittle. H. 3'5 — 4,
G. 2'2. Composition:
Silica ................................. 59-1
Alumina ............................. 16'9
Lime ................................. 9'2
Water ................................. 14'8
Occurs in small white glassy crystals in the augite-andesite
on Green Mountain, Jefferson County.
APPENDIX. 57
Monoclinic; priuuiry form a right rhombic prism. Occurs in attached
crystals and in layers and granular masses, frequently in a globular form.
Lustre vitreous ; pearly on planes of cleavage. Color various shades of
white, passing into red, gray and brown. Streak white. Transparent —
subtranslucent. Fracture subconchoidal, uneven. Brittle. H. 3'5 — 4.
G. 2'2. Composition:
Silica ................................. 59-1
Alumina ............................. 16'9
Lime ................................. 9'2
Water ................................. 14'8
100-0
Occurs in small white glassy crystals in the augite-andesite
on Green Mountain, Jefferson County.
Carbonate of Strontian.
Orthorhombic; primary form a right rhombic prism ; occurs crystallized
in hexahedral prisms, which are modified on the edges, or terminated by
pyramids; often acicular and in divergent groups; also occurs in column-
ar-globular forms, fibrous and granular. Lustre vitreous, inclining to res-
inons on uneven faces of fracture. Color pale asparagus-green, apple-
green, also white, gray, yeilow, and yellowish-brown. Streak white.
Transparent — translucent. Fracture uneven. Brittle. H. 8'5 — 4. G.
3'605 — 3'713. Composition:
Carbonic Acid .................... 29'8
Strontia .............................. 70'2
100-0
Occurs in the shape of small balls on celestite from the
the Garden of the Gods.
SXROMEYERITE. Sulphuret of Silver and Copper.
Orthorhombic ; isornorphous with copper glance. Usually massive. Lus-
tre metallic. Color dark steel-gray. Streak shining. Brittle. Fracture
subconchoidal. H. 2'5— 3. G. 6'2 — 6.3. Composition, silver, sulphur and
copper in variable proportions. Partial analyses of strorneyerite from Col-
orado mines returned the following :
Ag. Cu. S. Fe.
Little Giant mine, Clear Creek Co 50'00 21'00 16'60 3'40— W.C. Minger.
" " 48-00 35-00 16-00 — K. Neuman.
Grant mine, Boulder County 38'00 29'00 • — F. Graham.
Winning Card mine, Summit Co.. 49*00 36'00 IG'OO — R. Neuman.
Occurs in small masses and needle crystals coated with
chalcopyrite in the Little Giant mine, Clear Creek County.
In considerable quanty in the Grant mine, Boulder County,
and in the Winning Card and Black Prince mines, Summit
County. A variety carrying i y2 p. c. silver "is found in small
quantities in a lode on Saxon Mountain, Georgetown.
RHODOCHROSITE (p. 10.) — Crystallized and fibrous in the
Queen of the West mine, near Gray's Peak, associated with
alabandite.
58 APPENDIX.
Oxide of Titanium.
Tetragonal ; occurs in four or eight-sided prisms, terminated by pyramids,
either single or geniculated, and often striated longitudinally ; also in
reticulated masses formed by acicular and capillary rnacled crystals; also
massive and imbedded. Sttncture lamalJar. Color reddish-brown, pass-
ing into red, sometimes yellowish, bluish, violet, black, rarely grass-green.
Streak pale brown. Lustre metallic adamantine. Fracture subconchoidal,
uneven. Subtransparent — opaque. Brittle. H. 6 — 6'5. G. 4*18 — 4*25.
Composition : Titanic Acid :
Oxygen ................................. 39
Titanium .............................. 61
100
A small quartz pebble containing red rutile was found in
the Platte River at the foot of the mountains. It is in the
collection of Whitman Cross.
COSALITE (p. 13). — Analyses: I from the Alaska mine, Ou-
ray County, by Genth. II from Ouray County, by Konig:
i. n.
Bismuth ........................... 44'95 43'54
Lead ............................... 28'10 26'77
Silver .............................. 1'44 T35
Copper .................... . ........ 8-00 8'22
Zinc ...... ........................... 0'24 ......
Antimony .......................... 0'51 ......
Arsenic ............................. 0'04 ......
Selenium .......................... trace ......
Sulphur ............................. 16-80 16-54
100-08 96-42
BEEGERITE (p. 8). — Analyses: I from Ouray county, by
Konig. II from the Treasure Vault mine, Geneva District,
Clear Creek County, by Genth.
i. n.
Bismuth ........................... 19'35 19'81
Lead ................................ 45'87 50'16
Silver .............................. 9'98 15'40
Sulphur ........................... 13-37 14'59
88-57 99-96
ANNABERGITE (p. 37). — Analysis of annabergite from the
Gem mine, Silver Cliff, by Genth:
Arsenic Acid ..................... 36"64
Oxide of Nickel .................. 32'64
Oxide of Cobalt .................. O'fO
Lime .................. ............... 3'51
Magnesia ........ ......... ..... ..... 374
Water .............................. 23'94
100-97
CUPRITE (p. 40). — Very pure in veins near Pine Grove,
Platte Canon, associated with chrysocolla.
APPENDIX. 59
WITXICHENITE. Cupreous Sulphuret of Bismuth.
Orthorhombic ; occurs massive and disseminated ; also coarse columnar; or
an aggregate of imperfect prisms. Cleavage in one vertical direction.
Color steel-gray, tin-white, tarnishing pale lead-gray. Streak black. H.
3'5. G. 5. Composition :
Sulphur 19-44
Bismuth 42'11
Copper 38-45
100-00
According to T. B. Comstock wittichenite is of common
occurrence in the mines of San Juan county, and is rich in
silver.
AIKIIVIXE. Acicular Bismuth. Needle Ore.
Orthorhombic ; occurs in imbedded acicular four or six-sided prisms, in-
distinctly terminated, and striated longitudinally. Also massive. Lustre
metallic. Color blackish lead gray, with a pale copper-red tarnish. Frac-
ture uneven. H. 2 — 2'5. G. 6'1 — 6'8. Composition :
Sulphur 16-7
Bismuth 36'2
* Lead 36'1
Copper 11-0
100-0
Occurs in the mines of San Juan County in beautiful crys-
tals, and also in the Gladiator mine, Hinsdale county, carry-
ing about 5 per cent of silver (T. B. Comstock).
Orthorhombic; crystals often tabular; also massive and amorphous. Lus-
tre submetallic to vitreous and greasy. Color black, brown, brownish-yel-
low, straw-yellow. Streak gray to colorless. Opaque to subtranslucent.
Fracture small conchoidal to granular. H. 5 — 5'5. G. 5*4 — 5*9. Compo-
sition :
Tantalic Acid ....................... 62'5
Yttria ................................. 22'6
Lime ................................... 5'2
Protoxide of Iron .................. 3'4
Protoxide of Uranium ........... 6'3
100-0
W. B. Smith mentions the occurrence of a black variety,
in small masses, at Devil's Head Mountain, Douglas County.
WAD. Bog Manganese.
Occurs in amorphous and reniform masses, either earthy or compact, and
sometimes incrusting or as stains. Often loosely aggregated, and feeling
very light to the hands. Color dull black, bluish or brownish-black. H.
0'5. G. 3 — 4'26. Composition, oxide of manganese, but mixed with
other ingredients.
Occurs in small quantities in many localities throughout
the state, frequently staining the rocks black at the surface of
veins, and sometimes forming beautiful dendritic specimens,
called ' 'forest rock. ' ' Quite a large deposit near the springs
on Snake River, Summit County.
60 APPENDIX.
MYPERSXMEXE. Metalloidal Diallage. Labrador Hornblende.
Orthorhombic; occurs in foliated masses or imbedded in rocks. Lustre
somewhat pearly on a cleavage face, sometimes metalloidal. Color dark
brownish-green, grayish-black, pinchbeck-brown. Streak grayish, brown-
ish-gray. Translucent to nearly opaque. Brittle. H. 5 — 6. G. 3'392.
Analyses of hypersthene from Buffalo Peaks, Mosquito Range, by Hille-
brand :
Silica 51703 5M57 50'043
Alumina 1'720 2'154 2'906
Sesquioxide of Iron 0'304
Protoxide of Iron 17'995 18'360 J.7'812
Protoxide of Manganese.. 0'363 0'363 0'120
Lime 2*873 3'812 6'696
Magnesia 25'091 24'251 21'744
Soda 0-274
100-049 100-097 99*595
One of the essential constituents of the andesite and tufa
rocks of Buffalo Peaks, Mosquito Range.
PYROXENE.
Monoclinic ; primary form an oblique rhombic prism ; generally occurs in
short, thick crystals, and often in twins ; also amorphous, coarsely lami-
nar, granular and fibrous, fibres often fine and long. Lustre vitreous in-
clining to resinous, ^sometimes- pearly. Color green of various shades,
verging on one side to white or grayish-white, and on the other to brown
or black, Streak white to gray and grayish-green. Fracture conchoidal,
uneven. Brittle. H. 5—6. G. 3'23 — 3'5. Composition : Bisilicate of
various bases, the bases being lime, magnesia, protoxide of iron, protoxide
of manganese, and sometimes potash and soda.
Next to the feldspars, pyroxene is the most universal con-
stituent of the igneous rocks of the mountains.
PYROI*USITE. Gray Oxide of Manganese.
Orthorhombic; occurs crystallized, but generally in botryoidal and reni-
form masses, with a radiating, fibrous or columnar structure ; or in granu-
lar masses. Often soils. Lustre metallic. Color iron-black, dark steel-
gray, sometimes bluish. Streak black or bluish-black, sametimes subme-
tallic. Rather brittle. H. 2— 5'5. G. 4'82. Composition :
Manganese 63'3
Oxigen 36'7
100-00
Peale mentions its occurrence on Silver Heels Mountain,
near Fairplay, and in the San Juan country.
Orthorhombic; primary form a right rhombic prism; occasionally hemi-
hedial; occurs in columnar crystals striated vertically ; also fibrous and
massive, or radiating; sometimes granular. Lustre submetallic. Color
dark steel-gray, iron-black. Streak reddish-brown, sometimes nearly
black. Opaque ; minute splinters sometimes brown by transmitted light.
Fracture uneven. H. 4. G. 4'2 — 4'4, Composition :
Sesquioxide of Manganese ...... 89"8
Water ................................. 10'2
100-0
W. B. Smith reports its occurrence in small masses in the
region of Devil's Head Mountain, Douglas County.
APPENDIX. 6l
ARGENXOBISMUXIXE.
F. A. Genth gives the following analysis of argentobismutite from Lake
City, Hiusdale County :
Sulphur ............................. 16.66
Bismuth ............................. 52.89
Silver .............................. 26.39
Lead ................................ 406—100.00
Antimonial Lead Ore.
Orthorhombic; occurs crystallized in modified rectangular prisms, often
cruciform or compounded into shapes like a cog-wheel. Also massive,
granular compact. Lustre metallic. Color and slreak steel-gray, inclin-
ing to blackish lead gray or iron black. Opaque. Fracture conchoidal or
uneven. Brittle. H. 2.5 — 3. G. 5.7 — 5.9. Composition:
Sulphur .............................. 19.7
Antimony ........................... 25.0
Lead ..... .* ............................. 42.4
Copper .............................. 12.9—100.00
M. C. Ihlseng mentions the common occurrence of this min-
eral in the lodes of Bear and Anvil Mountains, San Juan
County. Its associate mineral is galena.
Asbestus (p. 30) of an olive-green color. Fibres usually coarse and stiff.
Needle-like fibres an inch or more in length in clear quartz
crystals near Calumet, Chaffee County.
A natural alloy of gold and silver in the proportion of two of gold to one
of silver, or,
Gold .................................... 65
Silver ......... . ........ . ................ 35—100
Color pale yellow to yellowish-white. Known crystals tabular, and im-
perfect cubes. G. 14 to 17.
According to P. H. VanDiest the ore in the Nelly mine,
San Miguel County, is crystallized electrum.
Copperas. Green Vitriol. Sulphate of Iron.
Monoclinic; in acute rhombic prisms. Occurs massive, pulverulent, bo-
tryoidal, reniform, stalactitic and crystallized. Lustre vitreous. Color
various shades of green, passing into white; becoming yellowish-white on
exposure. Subtransjtarent to translucent. Taste sweetish, astringent, and
metallic. Fracture conchoidal. Brittle. H.2. G. 1.832. Composition:
Sulphuric Acid ..................... 28.8
Protoxyd ol Iron .................. 25.9
Water.". ............................... 45.3—100.0
Proceeds from the decomposition of pyrite in the Black
Iron and other mines around Red Cliff; clear green crystals
and large masses. Crystals and small masses in the Pennsyl-
vania mine, Peru District, Summit County.
NATIVE CHARCOAL,.
F. F. Chishelm mentions the occurrence of native charcoal
in considerable quantities in the anthracite on the head of
Elk Head Creek in Routt County. According to Chisolm it
is of common occurrence in Colorado lignites. Charcoal is
found at various depths in the Bassick mine, Custer County.
62 APPENDIX.
AMJNITB. Alumstone.
Khornbohedral ; crystals modifications of an obtuse rhomboid. Massive,
having a fibrous, granular, or impalpable texture. Lustre of crystals vit-
reous, or a little pearly on the basal plane. Color white, grayish or red-
dish. Streak white. Transparent — subtranslucent. Fracture, flat conch-
oidal, uneven ; of massive varieties splintery ; sometimes earthy. Brittle.
H. 3 5—4. G. 2.58—2-752. Composition : "
Sulphuric Acid ................... 38.53
Alumina ........................... 37.13
Potash .............................. 11.34
Water ................................ 13.00—100.00
S. F. Emmons mentions its occurrence in the Iron mine at
Leadville. Probably occurs at a number of places along the
foot-hills with native alum.
SIDEROPHYULITE. (New). Black Mica. If. C. Lewis, Proc. Ac.
Nat. Sc Phila., 1880.
Color black; by transmitted light chrome green. Brittle. Analysis:
Silica ................................ 36.68
Alumina ........................... 20.41
Sesquioxyd of Iron ............. 1.55
Protoxyd of Iron ................. 25.50
Protoxyd of Manganese ........ 2.10
Magnesia ........................... 1.14
Lime ................................. 0.81
Soda ................................ 1.09
Lithia .............................. 0.37
Potassa .............................. 9.20
Water ............................... 1.01—99.86
Found in the Pike's Peak region.
(New). Telluride of Iron. C. U. Shepard, Contri-
butions to Mineralogy, 1877.
Color silver-white. Analysis by Edmond Fuchs :
Gold .............................. 5.228
Silver ............................. 4.198
Tellurium ........................ 19.650
Iron ................................ 70.624
Sulphur ........................... trace— 99.700
Occurs in the Grand View and Phil Sheridan mines, Sun-
shine, Boulder County.
URACOXIXE. Sulphate of Uranium.
Amorphous, earthy, or scaly, and of fine lemon-yellow color, or orange.
Composition :
Sulphuric Acid .................... 10.16
Sesquioxyd of Uranium ........ 66.05
Sesquioxyd of Iron .............. 0.86
Lime ................................. 2.62
Water ................................ 20.06—99.76
In the Wood lode, Leavenworth Gulch, near Central City,
with pitchblende.
STIBNITE (p. 23). — Large veins ol sulphide of antimony be-
tween Troublesome Creek and Lost Lake in Grand County.
Float masses of stibnite and quartz are found two or more feet
in thickness.
APPENDIX. 63
ANGLESITE (p. 7). — Occurs as the oxidation product of
galena in the mines around Red Cliff. It is abundant in the
form of minute crystals, or "sand." — Emmons.
ANTHRACITE (p. 47). — True anthracite is found on the head
of Elk Head Creek in Routt Co. F. F. Chisolm, who exam-
ined the field, says there are three veins, the upper four feet
thick, the second three and one half feet and the third one
foot in thickness. Analyses from the two upper veins :
Sulphur 0.79 0.44
Moisture 1,02 2.50
Volatile matter 9.66 3.20
Fixed Carbon 83.50 88.20
Ash 5.82 6.10
CALAMINE v. 27). — Abundant and crystallized in the Sun-
nyside mine, San Juan County. — Ihlseng.
GADOLINITE. — Massive in the upper canon of the South
Platte River.
JAROSITE (p. 7). — Minute but perfect crystals in the Black
Iron mine near Red Cliff. — Emmons.
LIMONITE (p. 33). — Pseudomorphs after pyrite in the Nelly
mine, San Miguel County.
MOLYBDENITE (p. 25). — Common in the lodes on Cement
Creek and near Chattanooga, San Juan County. — Ihlseng.
PHENACITE (p. 7). — Occurs in prismatic crystals on aqua-
marine on Mt. Antero in Chaffee County, and is thought to
be the decomposition product of beryl.
RUTILE (p. 58).— W. B. Smith found black ferriferous
rutile on St. Peter's Dome, El Paso County.
GARNET (p. 33. ) — Dr. Konig publishes the following analy-
sis of a massive titaniferous garnet from southern Colorado,
and comments on its relation to schorl omite:
Silica 30-71
Titanic Acid 8'11
Alumina 2'20
Sesquioxide of Iron 23'20
Lime 31 '40
Magnesia T22
Protoxide of Manganese 0' 46— 99.98
PYRITE (p. 42) — Octahedral crystals on Mount Richard
Owen, Anthracite Creek, Gunnison County.
CHRYSOCOLLA (p. 29). — Occurs near Pine Grove, in Platte
Canon, associated with red oxide of copper.
BISMUTHINITE (p. 9). — Occurs in the mines of San Juan
County.
64 0 APPENDIX.
CORUNDUM. Emery. Blue, Sapphire. Red, Ruby.
Rhornbohedral ; commonly occurs crystallized in six-sided prisms ; also in
obtuse and acute hexahedral pyramids; cleavage basal, sometimes perfect,
but interrupted. Also massive, granular or impalpable. Lustre vilreous,
sometimes pearly in the basal planes, and occasionally exhibiting a bright
opalescent star of six rays in the direction of the axis (asteriated sapphire).
Color blue, red, yellow, brown, gray and nearly white. Transparent to
translucent. Fracture conchoidal. Exceedingly tough when compact.
H. 9. G. 3.909 — 4.19. Composition, pure alumina:
Oxygen 46.6
Aluminum 53.4—100.0
W. B. Smith mentions the occurrence of a corundum shist
in ChafFee County which contains 35 per cent of corundum.
It occurs in thin flat crystals,_ and many of them are true sap-
phires.
SAPPHIRE. Blue Corundum.
The blue variety of corundum.
Thin flat crystals, the largest not more than 5mm in diam-
eter, are quite abundant in the corundum shist from Chaffee
County. The crystals are transparent and true sapphires.
PI^AGIOCI^ASE. Triclinic Feldspar.
The name for the group of triclinic feldspars, the two prominent cleavage
directions of which are oblique to one another.
The most abundant constituent of the andesite of Buffalo
Peaks. — W. Cross.
XMENARDIXE. Anhydrous Sulphate of Soda.
Orthorhombic: cleavage basal; primary form a right rhombic prism.
Occurs in rhombic octahedrons, simple or modified on the summit, aggre-
gated in crusts and druses. Color white. Translucent or pellucid. Lus-
tre vitreous. Effloresces and becomes covered on the surface with a white
powder on exposure to the air. Taste saline. Wholly soluble in distilled
water. Refracts doubly. H. 2.5. G. 2.6—2.73. Analysis :
Water and organic matter 19.10
Silica 5.20
Alumina and oxide of iron 14.40
Chlorine 2.40
Sulphuric Acid 25.80
Lime 8.80
Magnesia 3.90
Soda 19.10—98.70
Occurs in quantity at Burdsall's Lake near Morrison.
ZIRCON (p. 58). — Small crystals in the porphyrite of Ten-
Mile District, Summit County. — W. Cross.
POLYBASITE (p. 43). — The distinguishing silver ore of Up-
per San Miguel District and Marshal Basin, San Miguel
County. — Ihlseng.
ASBESTUS (p. 30). — Beautiful snow-white asbestus is found
near Jasper, Rio Grande County. Asbestus is also found in
float rock on Arapahoe Peak.
APPENDIX. ^ 65
DYSCRASIXB. Antimonial Silver.
Orthorhombic ; occurs in hexagonal prisms and stellate forms ; also mass-
ive, disseminated, or in grains. Color and streak between silver-white and
tin-white, often tarnished yellow or reddish. Lustre metallic. Easily
frangible. Soft and slightly malleable. H. 3.5 — 4. G. 9.44 — 9.82. Comp.:
Silver 78
Antimony 22 — 100
Hills and Endlich mention the occurrence of dyscrasite in
the mines of Poughkeepsie Gulch, San Juan county.
MYDROPMA^B. Variety of Opal.
Massive, amorphous. Lustre vitreous, frequently subvitreous. Translu-
cent. Color whitish, or light colored. Adheres to the tongue and becomes
more translucent or transparent in water. Composition :
Silica 93.00
Alumina 2.00
Water 5.00—100.00
A white and nearly opaque variety of hydrophane, in
rounded lumps, with a white chalky or glazed coating, is
found in the State, but the locality is a secret. When water
is dropped upon it, it first becomes very white and chalky,
and then gradually perfectly transparent. This property is
developed so strikingly that the name "Magic Stone" has
been proposed for it, and its use suggested in rings, lockets,
charms, etc., to ^conceal photographs, hair or other objects
which the wearer wishes to reveal only when his caprice
dictates (Kunz\
R.IO1SITB. Bismuth-Tetrahedrite.
Has a conchoidal fracture, an iron-black color, black streak and greasy-
metallic lustre. An analysis of the Switzerland mineral gave :
Sulphur 29'IQ
Arsenic 11'44
Antimony 2'19
Bismuth 13'07
Copper 37'52
Silver 0'04
Iron 6-51
Cobalt 1-20— 101-07
Abundant in the Yankee Girl mine, Ouray county, carrying
about, two per cent of silver.
ZOR.GI'TB* Seleniuret of Lead and Copper.
Massive, granular. Lustre metallic. Color dark or light lead-gray, some-
times inclining to reddish, and often with a brass-yellow or blue tarnish.
Streak darker. Brittle. H. 2'5. G. 7 — 7 '6. Composition :
Selenium 34
Lead 50
Copper 15
Silver 1—100
Occurs in quantity in the Pearl lode, Minnesota gulch, San
Juan county.
66 t APPENDIX.
RuTiLE (p. 58). — Small jet-black tetragonal crystals occur
in quartz gangue near the Eureka tunnel, St. Peter's Dome,
El Paso county, associated with arfvedsonate and zircon, and
closely resembling in form the latter mineral. An analysis
by Eakins gave :
Titanic Acid 9473
Oxyd of Iron 3'77
Silica 1-37
Water 0'71— 10078
SCHIRMERITE (p. 32). — In the Santa Cruz mine, Howard's
Fork, San Miguel county, with bismuthinite, chalcopyrite
and galena.
EPIDOTE (p. 36). — Good single crystals are found near the
Colorado Coal and Iron Go's mine at Calumet.
ANGLESITE (p. 7). — L,arge masses in the Madonna mine,
Chaffee county, often as pseudomorph after galena.
ARSENOPYRITE (p. 40). — Near Ruby camp, Gunnison coun-
ty. On Mount Wilson, San Miguel county. .
BORNITE (p. 14). — In the Plutus mine, Idaho Springs. In
the mines of Red Mountain district, San Juan and Ouray
counties. Near Maysville, Chaffee county. Gem mine, Fre-
mont county, with niccolite.
CHALCOCITE (p. 37). — Occurs almost alone, in sandstone
with matrix of calcite, in San Miguel county. Massive at
Ironton, Ouray county.
HEMATITE (p. 34). — Large, irregular deposit in the Breece
mine, Leadville. Large beds near Ashcroft and Carbondale,
Pitkin county.
STROMEYERITE (p. 57). — Rarely in the Plutus mine, Idaho
Springs. In quantity in the Yankee Girl mine, Ouray Co.
TENNANTITE (p. 8). — Frank Hough mine, Hinsdale Co.
GRAPHITE (p. 27). — In quartz veins 2^2 feet thick on
branches of Quartz Creek, Gunnison county.
MAGNETITE (p. 34). — Grayback gulch, Costilla county.
Titaniferous variety on Iron mountain, Fremont county.
Both worked by the Colorado Coal and Iron Company. A
pure magnetite in large quantity on Cebolla Creek, and titan-
iferous magnetite near Snowmass mountain, Gunnison county.
In quantity near Hamilton, Park county. Near Ashcroft and
Carbondale, Pitkin county.
AcTiNOUTE (p. 30). — Light green and bluish green actino-
lite is found on Mt. Ouray, Chaffee County.
APPENDIX. 67
NATIVE SULPHUR (p. 6). — In the Queen of the West mine,
Peru District, Summit County, with alabandite and rhodo-
chrosite. In the S. S. mines, Park County. In Routt Co.,
but the exact locality is not known. In the Mineral Chief
lode, Georgetown, with galena.
RHODOCHROSITE (p. 10). — Rich red, transparent crystals
in the John Reed mine at Alicante, Lake county. Some
cleavage pieces are as pellucid as Iceland spar and show the
same strong double refraction. It also occurs opaque, mass-
ive and cleavable, enclosing bright cubic crystals of pyrite.
Analysis by James B. Macintosh gave :
Protoxyd of Manganese 58.325
Protoxyd of Iron 3.615
Carbonic Acid (by difference) 38.06 —100.00
At the Ule mine, Lake City, opaque flesh-colored crystals,
rounded and curved like dolomite, are found on galena.
Large masses of white, yellowish and light pink color as
stalagmites in the Stevens mine, near Gray's Peak.
HYALITE (p. 41). — Crusts on the hypersthene-andesite of
Buffalo Peaks, Chaffee county.
SCHEELITE (p. 27). — In crystals in some of the mines of
Baker Park, San Juan county. — (EndlicJi).
CUPRITE (p. 40). — Sweet Home mine, Buckskin, Park Co.
North Fork of the Poudre, Larimer county, with native cop-
per and chalcocite.
CELESTITE (p. 25). — On Apishapa Creek.
HESSITE (p. 28). — Mines of Red Cliff, Eagle county. Oc-
casionally met with in the mines of La Plata county.
PETZITE (p. 43). — Hotchkiss mine, Hinsdale county.
SYLVANITE (p. 32). — In quartz veins on Junction Creek,
and at the head of the Rio la Plata, La Plata county.
APOPHYLLITE (p. 15). — Endlich mentions its occurrence on
Hunt's Peak, Fremont county.
BISMUTHENITE (p. 9). — Near Silverton, in long steel-blue
and iridescent needles, associated with hubnerite, tetrahedrite
and drusy quartz.
OPAL (p. 40). — Nodules of milk-white opal, some having
moss-like markings, on Badger Creek, South Park.
FLUORITE (p. 10). — In veins with quartz in Poughkeepsie
gulch, San Juan county. On Kelso mountain, Clear Creek
county.
CHRYSOCOLLA (p. 29).— In the Sangre de Christo moun-
tains, Custer and Saguache counties.
68 APPENDIX.
Penjield, Am. Jr. Sc.t July, 1888.
Monoclinic ; crystals generally tabular in habit, transparent, colorless or
slightly yellowish. Lustre vitreous. H. 6 — 7. G. 2'598. Analysis of
Colorado mineral gave :
Silica .................... ............. 51.8
Glucina ... ........................... 39.6
Lime ................................. 1.0
Water ................................ 8.4—100.8
Found on Mt. Antero, Chaffee county, with phenacite, or-
thoclase, beryl, muscovite and fluorite. Occurs in small thin
rectangular blades attached to quartz, and having the shape of
a thin slice cut from the side of a cylinder parallel to its axis.
PYRR.HOXIXE. Magnetic Iron Pyrites.
Hexagonal ; commonly massive and amorphous ; structure granular. Lus-
tre metallic. Color between bronze-yellow and copper- red, and subject to
speedy tarnish. Streak dark grayish-black. Brittle. Magnetic, being
attractable in fine powder by a magnet, eyen when not affecting an ordi-
nary needle. H. 3'5 — 4'5. G. 4'4 — 4.68. Composition :
Sulphur .............................. 39'5
Iron ................................... 60-5— 100-0
Occurs in small quantity in the lodes of Needle mountains,
San Juan county.
SPHBROSIDBRITB. Concretionary Siderite. Carbonate of Iron.
In globnlar concretions, either solid or concentric scaly, with usually a
fibrous structure. Composition :
Carbonic Acid ....................... 37'9
Protoxyd of Iron.- ................ 62'1 — lOO'O
A thin seam of spherosiderite occurs above the coal of the
Laramie formation in many parts of the state. In some places
it has weathered out in nodules, which are found upon the
plains in great quantity. It is found near Trinidad and El
Moro in Las Animas county, Walsenburgh in Huerfano coun-
ty, and Marshall in Boulder county.
H VmtOPIIAXK. Variety of Opal.
Massive, amorphous. Lustre vitreous, frequently subvitreous. Translu-
cent. Color whitish, or light colored. Adheres to the tongue and becomes
more translucent or transparent in water. Composition :
Silica .......................................... 93.00
Alumina ...................................... 2.00
Water ......................................... 5.00—100.00
A white and nearly opaque variety of hydrophane, in
rounded lumps, with a white chalky or glazed coating, is
found in the State, but the locality is a secret. When water
is dropped upon it, it first becomes very white and chalky,
and then gradually perfectly transparent. This property is
developed so strikingly that the name uMagic Stone" has
been proposed for it, and its use suggested in rings, lockets,
charms, etc., to conceal photographs, hair or other objects
which the wearer wishes to reveal only when his caprice
dictates (Kunz\
APPENDIX. 69
SAMARSKIXB. Hillebrand, Proc. Col Sc. Soc,, 1888.
Orthorhornbic. Lustre of surface of fracture shining and submetallic.
Color velvet-black. Streak dark reddish-brown. Opaque. Fracture sub-
conchoidal. H. 5.5—6. G. 5.614—5.69.
Occurs in granitic debris on Devil's Head Mountain, Dong-
las County, in fragments of all sizes up to that of a chestnut,
without crystal form. The following analysis by Hillebrand
shows the composition:
Tantalic Acid 27.03
Columbic Acid 27.77
Tungstic Acid 2.25
Oxide of Tin 0.95
Zifconia 2.29
Protoxyd of Uranium 4.02
Thoria 3.64
Protoxyd of Cerium 0.54
Oxide of Didymium and Lanthanum... 1.80
Oxide of Erbium 10.71
Yttria 6.41
Sesquloxyd of Iron 8.77
Protoxyd of Iron 0.32
Protoxyd of Manganese 0.78
Zirconia 0.05
Oxide of Lead 0.72
Lime 0.27
Potassa 0.17
S'-da and Lithia 0.25
Water 1.58
100.31
MEGABASITE. Tungstate of Manganese.
Orthorhombic ; usually occurs in fine needles. Lustre vitreous, a little
adamantine. Color brownish-red, clover- brown to yellowish-brown, with
a reddish-brown to hyacinth-red translucency. Streak pale yellowish-
brown to ochre-yellow. H. 3.5 — 4. G. 6.45.
H. F. Keller gives the following analysis of megabasite
from Bonita Mountain, near Silverton:
Tungstic Acid 74.24
Oxide of Manganese 21.09
Protoxyd of Iron 2.06
Oxide of Copper 0.11
Oxide of Manganese trace.
Silica 2.13
99.63
Lime-Aluminagarnet.
A cinnamon-colored variety of garnet. Composition :
Silica 41
Alumina 23
Oxide of Iron 4
Lime 32—100
Longfellow gulch, ChafFee county, in dark rhombic dodeca-
hedrons, disseminated through chloritic schist. In metamor-
phosed limestone near Calumet. They have finely polished
faces and beautiful clear color.
70 APPENDIX.
WARREBJIXE. (New.) Sulphantimonate of Lead. L. G. Eakins, Proc-
Col. Sc. Soc., 1888.
Small acicular crystals forming matted wooly-like masses. Color grayish-
black, occasionally iridescent. Analysis by Eakins:
Lead ............................................ 39.33
Antimony ...................................... 36.34
Iron ............................................. 1.77
Silver, Copper, Manganese .- ............. trace.
Sulphur .............. .......................... 21.19
Insoluble gangue .............................. 52
99.15
Found in the Domingo lode, on the ridge between Canon
and Baxter Basin, Gunnison county. Named after E. R.
Warren of Crested Butte.
Sulphuret of Silver and Antimony. Eakins,
Proc. Col. Sc. Soc., 1888.
Monoclinic; occurs in small, deeply striated prisms. Lustre metallic.
Color and streak light steel gray, inclining to silver white, also blackish
lead gray. Yields easily to the knife, and is rather brittle. Fracture sub-
conchoidal — uneven. H. 2 — 2.5. G. 6 — 6.4. Comp.: Sulphur 18.6, anti-
mony 25.9, lead 31.2, silver 24.3. — 100. Silver often replaced by lead.
Occurs in a mine on Augusta Mountain, Gunnison Co. , in
silicious gangue together with pyrite and sphalerite, and
forms groups of acicular crystals which are elongated prisms,
deeply striated, but too small to be measured. The analysis
is as follows:
Silver....: ...................................... . trace.
Lead ............................................. 55.52
Iron ............................................. trace.
Antimony ................. . .................... 25.99
Sulphur (calculated) ........................ J8.98
100.40
ENARGITE (p. 13). — In the mines of Summit district, Rio
Grande county.
JET (p. 45). — On the Trinchera mesa, southeast Colorado.
Moss AGATE (p. 18). — In nodules on Badger Creek, South
Park.
ORTHOCLASE (p. 12). — Excellent crystals are found in the
slide rock just above the river on Crested Butte Mountain,
Gunnison County.
AMETHYST (p. 23). — Pale colored amethyst is found on Car-
nero Creek, Saguache County. In form they are quite re-
markable, the prismatic faces being enormously large, while
the terminal pyramidal faces are very minute. "Phantom
crystals" are often enclosed, and occasionally liquid inclu-
sions with movable bubbles.
CLEAR CREEK COUNTY MINERALS.
Clear Creek County is pre-eminently mineral-bearing, the
only tillable land being a few rods in width along the streams.
The southeastern portion of the county, however, is valuable
only for timber, as mineral veins in that region either do not
exist or have not been discovered. The formation is archean,
veined with dikes of eruptive rocks, in which porphyry pre-
dominates. Heavy-bedded and thinly-laminated gneiss, red
and gray granite, schist, syenite, felsitic and hornblendic
rocks pass by imperceptible phases from one to the other in
inextricable confusion, and the dip of the rocks are as variable
as their structural character.
It is somewhat remarkable that so few accessory minerals
have been found in the granite and kindred rocks, and equal-
ly remarkable that the minerals found in the veins are locally
few in variety and seldom crystallized. Taken as a whole,
however, Colorado is probably the richest in variety of min-
erals of any known region. But the number of local miner-
als might be materially increased were the finders as much
interested in learning the nature of the minerals that pass
through their hands as in determining their gold and silver
value. The following minerals are found in Clear Creek
Coiinty :
Acanthite (orthorhombic silver glance). — A few small
crystals were found in a lot of polybasite crystals from the
Emma mine.
Albite (soda feldspar). — A constituent of some of the gran-
itic rocks, particularly on Fall River.
Amethyst.— r-A few specimens of good color have been
found in a lode near Dumont and on Chicago Creek.
Anglesite (sulphate of lead). — Aggregations of small crys-
tals in the Freeland mine. Small crystalline masses in the
Troy mine, Georgetown, intimately associated with cerussite.
Aragonite (carbonate of lime). — Large beautiful specimens
of coralloidal form were found in the Marshall tunnel a num-
ber of years ago. A shaft near the Argentine lode, on Leav-
enworth Mountain, furnishes yellow tinted specimens.
2 Clear Creek County Minerals.
Argentite (silver glance). — In small quantities in nearly
all the silver mines. Masses weighing two to three pounds
have been found in the Colorado Central and Saxon mines.
Crystals rare and quite .small.
Arsenopyrite (arsenical pyrites). — Occasionally found in
the veins about Empire, Idaho and in Geneva District.
Autunite (phosphate of uranium and lime). — Small green-
ish-yellow tabular crystals in the Peabody lode, near George-
town, and in a lode on Chicago Creek.
Azurite (blue carbonate of copper.) — Occurs as an incrus-
tation near the surface of many of the lodes.
Barite (heavy spar). — Of frequent occurrence in some of
the veins. Clusters of amber-colored crystals in the 7:30
mine. In the Little Giant mine in thin white crystals. Small
tabular crystals in the Oneida and many other lodes.
Biotite (black mica). — A constituent of much of the gran-
ite and eruptive rocks. •
Bornite (purple copper ore). — Of frequent occurrence in the
gold mines. Handsome specimens in the Neath.
Calcite (carbonate of lime). — Occurs in small quantities
in many of the mines. Nail-head crystals in the Terrible.
Cerargyrite (horn silver, chloride of silver.) — Thin crusts
on the surface ores from some of the lodes on Democrat and
Lincoln Mountains.
Chalcanthite (blue vitriol). — Forms on the walls of the
Whale Tunnel, near Idaho.
Chalcedony. — Beautiful botryoidal specimens have been
found in the mines at Idaho. Occasionally met with in the
Little Giant and other veins.
Chalcopyrite (copper pyrites). — Of general occurrence but
in less quantity than pyrite, and carries more gold and
silver. A few fine crystals., usually studded with minute crys-
tals of tennantite, have been found in the Freeland mine.
Chrysocolla (silicate of copper). — In the Champion lode,
near Idaho.
Dolomite (magnesian limestone). — Of frequent occurrence
in the veins in Ohio District. Occasionally found in other
lodes.
Enargite (arsenical sulphide of copper). — A small amount
is found in the surface ores of the Centennial mine, associated
with native copper.
Clear Creek County Minerals. j
Epidote. — Massive and crystallized in the granitic rocks
between Georgetown and Green Lake. Very good crystal on
Floyd Hill.
Fibrolite. — Inferior fibrolite of a grayish-green color oc-
curs in the granite on Sherman Mountain.
Fire Opal. — A very handsome opal showing bluish and
yellowish flames, and greatly resembling sofhe Mexican opals,
is found in a felsite rock in Gilson Gulch, near Idaho.
Fluorite (fluor spar). — Impure massive fluorite of deep
purple color is found in some of the lodes on McCJellan Mt.
Galenite. — The most abundant mineral in the silver mines.
Good crystals in the Dunderberg, Terrible and Little Giant
mines. In many of the mines it occurs in all grades from
coarse cubes to extremely fine granular, and sometimes lam-
ellar. The percentage of silver it carries varies from a few
ounces to several hundred ounces per ton.
Garnet. — Large brown garnets are occasionally found im-
beded in granite on Griffith Mountain.
Gibralter Rock. — A ledge of this variety of limestone is
located near Idaho Springs. When polished it is quite hand-
some.
Hematite. — Ocherous hematite is found near the surface
of many of the veins.
Hornblende. — Of general occurrence in the granitic rocks.
An essential constituent of syenite, and is frequently found
massive. No good crystals have been found.
Hornstone. — Of frequent occurrence in the mines, forming
part of the gangue rock.
Kaolinite (porcelain clay). — Masses showing crystalline
structure in the Silver Mountain lode, near Empire. Occurs
in many other lodes in small quantity.
Linarite (cupreous anglesite). — A mineral having the gen-
eral characteristics of linarite is found at the surface of some
of the lodes on Red Elephant Mountain.
Magnetite (magnetic iron). — Crystals of magnetite are of
frequent occurrence in granite. The granite quarried at
Brownville is liberally sprinkled with crystals of this mineral.
Malachite (green carbonate of copper). — Occurs as a stain
or incrustation at the surface of man of the veins.
.— Found in small quantities at the surface, of the
Colorado Central vein.
«
1 /I
4 Clear Creek County Minerals:
Micaceous Iron (hematite). — Quite abundant between Clear
Creek and Mill Creek.
Molybdenite. — Small masses in the Louisiana lode, Sher-
man Mt. , in the. Colorado Central mine, in the Moline Tun-
nel, in several localities on Red Elephant Mt. , and in Daily
District.
Muscovite (corfUnon mica). — Common in archean rocks.
Sometimes found in large masses. Very good crystals are
found in a mica claim near Graymont.
Native Copper. — Small dendritic scales in the Centennial
and McClellan mines ; wires and small masses in the Pitts-
burg mine, Empire. Loose masses have been found in the
soil about Idaho.
Native Gold. — -In placers and in Veins along the creek
from Idaho to Empire, on Fall River and in Argentine Dis-
trict. Many of the silver mines also carry an appreciable
amount of gold.
Native Silver. — In leaf and wire form in many of the mines
throughout the county. Nuggets in the talc bed on Fall
River.
Niccolite (arsenical nickel). — Occurs sparingly in the Rosa
lode, Dumont.
Orthoclase (common feldspar). — One of the most common
rocks throughout the county and occurs in immense masses
as well as a constituent of nearly all country rock.
Polybasite. — Next to gray copper polybasite is the most
abundant rich silver ore found in the county. Crystals are
quite abundant in the Emma mine, and some have been
found more than an inch in their longest diameter. A few
crystals are met with in the Colorado Central. It usually
occurs massive, when it is difficult to distinguish from gray
copper.
Proustite (light ruby silver ore). — Small masses and mi-
nute translucent crystals in the Colorado Central mine.
Pyrargyrite (dark ruby silver ore). — Of general occurrence
in the silver mines but usually in small quantity. Probably
more is found in the Colorado Central than in any other
mine. Crystals have never been noticed.
Pyrite. — Almost universally in the mines. Particularly
abundant at Empire and Idaho, and in the "gold belt" lodes
at Georgetown. Usually massive ; crystals quite small and
rarely vary from the cube. Carries gold and a little silver.
Clear Creek County Minerals. 5
Pyromorphite (phosphate of lead). — Sparingly in some of
the mines on Democrat Mountain.
Quarts. — In large masses at the eastern end of the county.
Forms part of the gangue rock of the mines. Crystals fre-
quent but usually small.
Rhodochrosite (carbonate of manganese). — Some very pretty
crystals are found in the Danube lode, near Idaho Springs.
Rose Quarts. — Beautiful rose-tinted masses on Floyd Hill.
Crystals in the Little Giant mine.
Schirmerite (bismuth silver ore). — In small masses in the
mines of Geneva District.
Siderite (carbonate of iron). — Of frequent occurrence, both
massive and crystallized, in the mines in the Trail Creek re-
gion. Occasionally in other mines.
Sphalerite (zinc blende). — Abundant, especially in the
Georgetown and Silver Plume district. Varies in color from
amber to black. Large clusters of black crystals in the Maine
mine, some crystals three inches in diameter. Usually car-
ries but littje silver.
Stromeyerite. — A variety carrying a little more than one
per cent of silver is found in small quantities in the Algon-
quin, Silent Friend and other lodes on Saxon Mountain.
In large quantities in the Plutus mine, mixed with bornite,
and carrying 25 per cent of silver. In small acicular crystals
in the Little Giant mine, and carrying about 50 per cent of
silver.
Talc. — An extensive bed near the head of Fall River which
is being sluiced by the Alice company for the gold it contains.
Tennantite (arsenical sulphide of copper). — Clusters of
highly polished crystals from microscopic size to ^ of an inch
in diameter in the Freeland mine.
Tourmaline. — Inferior tourmaline is found on Baker Moun-
tain and near Green Lake.
Tetrahedrite (gray copper). — The most abundant rich silver
ore. Gray copper from 'the mines in the vicinity of George-
town and Silver Plume carries as high as 30 per cent of silver,
while that from the mines east of Georgetown and in the
vicinity of Idaho Springs, and in Geneva District rarely con-
tains more than one per cent of silver. A few coarse crystals
have been found in the Geneva District mines.
Uraninite (pitchblende). — Small masses have been found
in the Jo Reynolds mines.
Gilpin County Minerals,
GILPIN COUNTY MINERALS.
Albite (soda feldspar). — A constituent of some of the arch -
ean rocks.
Amethyst. — Small beautiful crystals of good color have
been found in the gravel in Nevada.
Arsenopyrite (arsenical pyrites). — Occasionally found in
small masses in the Kansas, Illinois, Burroughs, California
and other mines.
Azurite (blue carbonate of copper.) — Occurs as an incrus-
tation or stain at the surface of many of the mines.
Barite (heavy spar). — Of frequent occurrence in some of
the mines, and occasionally crystallized.
v Biotite (black mica). — A constituent of much of the gran-
ite and eruptive rocks.
Bornite (purple copper ore). — Of general occurrence in the
mines in greater or less quantities. Crystals rare. .
Calcite (carbonate of lime).— Occurs in small quantities
in many of the mines.
Chalcanthite (blue vitriol). — Near Black Hawk, in a de-
posit. In many of the old mine dumps about Central.
Chalcedony. — Small masses occasionally met with in many
of the mines.
Chalcopyrite (copper pyrites). — Of general occurrence and
one of the principal ores of gold. Crystals frequent.
Covellite (indigo copper). — In grains and as a powder in-
Pewabic, Gunnell, Sapp and other lodes near Central.
Enargite (arsenical sulphide of copper). — Massive and finely
crystallized in the Powers mine, Russell District.
Epidote. — Massive and crystallized in the granitic rocks
throughout the county.
Float Stone. — Snow-white masses showing gold have been
taken from the Mammoth mine, Central.
Fluorite (fluor spar). — Met with occasionally in some of
the veins.
Galenite. — Abundant in many of the mines. Fine crystal-
lized specimens have been found in the Glennan and Running
mines, Black Hawk, the Delaware and Calhoun lodes, Rus-
sell District, the Mount Desert and Forks lodes at Nevada.
Crystal two inches across have been found in the Glennan.
Gilpin County Minerals. j
Garnet. — Iron garnets are quite abundant in the vicinity
of Central.
Hornblende.- — Of general occurrence in the archean rocks.
Hornstone. — Of frequent occurrence in the mines, forming
part of the gangue rock.
Kaolinite (porcelain clay). — In greater or less abundance
in all the mines.
Magnetite (magnetic iron). — Crystals of magnetite are of
frequent occurrence in granite. Octahedral crystals on Gun-
nell Hill.
Malachite (green carbonate of copper). — Occurs as a stain
or incrustation at the surface of many of the veins.
Melanterite (copperas, green vitriol). — In the dumps of
many of the old mines.
Molybdenite. — Small masses in the Leavitt lode.
Muscovite (common mica). — Common in archean rocks.
Sometimes found in large masses.
Oligoclase (aveuturine feldspar). — A constituent of much of
the archean rocks.
Native Copper.— Small dendritic coatings in a number of
the lodes. Masses weighing several pounds have been found
in the Narraganset and Gregory mines.
Native Gold. — In placers and in the veins. Beautiful mi-
crosopic crystals in the Gunnell, Gregory, Bates and other
mines. Strings of minute crystals, forming chain-like wires,
are frequently found.
Native Silver. — In leaf and wire form in the Coaley and
other mines.
Orthoclase (common feldspar). — One of the most common
rocks throughout the county and occurs in immense masses
as well as a constituent of nearly all of the rocks. Crystals
in porphyry on Gregory Hill.
Pyrite (iron pyrites). — Abundant, massive and crystallized,
in all the lodes, and composes the greater part of the gold
ore. Beautiful crystallized specimens and radiated and bo-
tryoidal masses common in many of the mines. Cubes from
one to three inches across have been taken from the King-
ston, Hill House and S. P. Chase lodes in Russell District.
A lode near the head of Virginia Canon has furnished a great
many modified crystals.
Rose Quarts. — In small masses in the vicinity of Central
and other localities.
8 Gilpin County Minerals.
Quartz. — Common in large masses. Forms part of the
gangue rock in the mines. Crystals frequent but usually
small. An essential constituent of granitic rocks.
Siderite (carbonate of iron). — Of frequent occurrence, both
massive and crystallized, in the mines.
Rock Crystal. — Doubly terminated limpid crystals common
in the gravel on Quartz Hill. The crystals are small but
quite perfect.
Sphalerite (zinc blende). — Abundant in many of the lodes.
Clusters of tetrahedral crystals in the Coaley lode, Black
Hawk. Crystallized in the Delaware and Calhoun lodes.
Talc. — In small quantities in nearly all the mines.
Tourmaline. — Black crystals near Nevada.
Tetrahedrite (gray copper). — Not unfrequently found in a
number of mines, sometimes crystallized.
Uraninite (pitchblende). — Abundant at one time in the
Wood lode, L/eavenworth Gulch. A few imperfect crystals.
Uraconite. — Occurs as a yellow coating on pitchblende in
the Wood lode.
Cerussite (carbonate of lead). — Of rare occurrence at the
surface of some of the veins.
Lepidomelane (iron potash mica). — A constituent of some of
the granite.
NEEDS VERIFICATION.
Aurichalcite. — Jones lode, near Nevada.
Allophane. — Cincinnati lode.
Calamine.
Glockerite. — On old dumps.
Goslarite. — Wood lode, Leavenworth Gulch.
Greenockite. — Jones and Dallas lodes.
Jarosite. — Wood lode.
Lievrite. — Below Black Hawk.
Magnesite. — Bobtail, Running and Pewabic lodes.
Marcasite.
Native Sulphur. — Jones lode, Nevada.
Plumbogummite.— \32ti\as lode, Black Hawk.
Pyrrhotite.
Smithsonite. — Jones lode, Nevada.
Uranochalcite. — Wood lode.
Willemite. — Jones lode, Nevada.
Wulfenite.— Gunnell Hill.
Zincite. — Jones lode, Nevada.
Zippeite. — Wood lode.
Grand County Minerals.
GRAND COUNTY MINERALS.
Albite (soda feldspar). — A constituent of some of the arch-
aean rocks.
Agate. — Abundant along Williams River; on the ridge be-
tween Hot Sulphur Springs and Corral Creek ; on the moun-
tains at the mouth of Willow Creek.
Agatized Wood. — Abundant on the ridges north of Willow
Creek. Also between Hot Springs and Corral Creek.
Argentite (silver glance). — In small quantities in the min-
eral veins in Campbell district.
Azurite (blue carbonate of copper.) — Occurs as an incrus-
tation in copper veins in the Park Range at the head of a fork
of the North Plate River.
Barite (heavy spar). — Reported to occur in extensive beds
on Vasquez Creek.
Basanite (touch stone). — Sparingly along Willow Creek.
Biotite (black mica). — A constituent of much of the gran-
ite and dike rocks of the mountains and eruptive rocks of Mid-
dle Park.
Bismutite (carbonate of bismuth). — Found near Cummuns
City, North Park. Needs verification.
Brown Coal (lignite). — Extensive veins in North Park and
exists at various points on the divide between North and Mid-
dle Parks.
Byerite. — A name given to the coal found in Middle Park.
It belongs to the class caking bituminous, and resembles al-
bertite in the large amount of gas and tarry oil yielded. It
melts and intumesces when heated.
Carnelian. — Sparingly on the ridge south of Willow Creek.
Cerussite (carbonate of lead). — Frequently found in small
masses near the surface of mineral veins.
Chalcedony. — Abundant on the ridges on both sides of
Willow Creek. Common on the ridge between Hot Springs
and Corral Creek.
Chalcocite (copper glance, sulphuret of copper). — In copper
veins in the Park Range. Bancroft Library
Chalcopyrite (copper pyrites). — Of general occurrence in
small quantities in the mines.
TO Grand County Minerals.
Chrysoprase. — Sparingly in geodes on upper Grand River.
Cuprite (red oxide of copper). — In copper veins in the Park
Range.
Cyanite. — Occurs in the quartzite of Medicine Bow Peak.
Epidote. — Massive and crystallized in the granitic rocks.
Galenite. — Abundant in many of the mines. Massive veins
near the head of Troublesome Creek.
Heliotrope (bloodstone). — Fine specimens occasionally met
with in the vein of green jasper on the hill at the junction of
Willow Creek and Grand River.
Hornblende. — Of general occurrence in the archaean rocks.
Hypersthene. — A constituent of the feldspar basalt from
Grand River, above Hot Springs.
Jasper. — Veins of green, red and yellow jasper on the hill
at the junction of Willow Creek and Grand River. Ribbon
jasper is quite, common at this locality. Red and yellow jas-
per is more or less abundant on the ridges along Willow
Creek, in the vicinity of Hot Springs, and in the streams.
Lepidomelane (iron potash mica). — A constituent of some of
the granite.
Magnetite (magnetic iron). — An accessory mineral of much
of the granite.
Malachite (green carbonate of copper). — Occurs as a stain
or incrustation at the surface of many of the copper veins in
the Park Range.
Moss Agate. — Quite abundant on the south side of Williams
River, three or four miles from the Grand.
Mottled Agate. — On Williams River; in the vicinity of
Hot Springs ; Willow Creek, and numerous other localities.
Muscovite (common mica). — Common in archsean rocks>
frequently occurring in large masses.
Native Bismuth.— Occurs in small particles in bismutite at
Cummuns City. The find is not satisfactorily verified.
Native Gold. — In the alluvium of Willow Creek.
Native Silver. — In leaf and wire form in some of the silver-
bearing veins.
Oligoclase (aventurine feldspar).— A constituent of much of
the archsean rocks.
Onyx. — Sparingly with chalcedony on the ridge south of
of Willow Creek.
Jefferson County Minerals, ri
Orthoclase (common feldspar). — The most abundant con-
stituent of the archsean rocks.
Plasma. — Occurs in geodes found on upper Grand River.
Pyrargyrite (dark ruby silver ore). — In small quantities in
the lodes of Campbell district.
Pyrile (iron pyrites). — More or less abundant in the min-f
eral veins.
Pyroxene. — Next to the feldspars, pyroxene is the most
universal constituent of the igneous rocks.
Quartz. — Common, in crystal, small masses and a constitu-
ent of metamorphic and sedimentary rocks.
Sardonyx. — Fine specimens occasionally met with on the
ridge south of Willow Creek, a mile or two from the Grand.
Stibnite (antimony glance). — Float masses of stibnite and
quartz, two feet in thickness, are found between the head of
Troublesome Creek and Lost Lake.
Sphalerite (zinc blende). — Abundant in many of the lodes.
Tetrahedrite (gray copper). — Not unfrequently found in
the mines at Lulu.
JEFFERSON COUNTY MINERALS.
Actinolite. — Columnar masses of green color near Bergen
ranch on Bear Creek, and at the entrance of Coal Creek canon.
Agate. — Mottled agate common on Green Mountain.
Agatized Wood. — Abundant on Table Mountains.
Alabaster. — Massive white and mottled alabaster in Jurassic
shales near Morrison.
Albite (soda feldspar). — A constituent of some of the arch-
sean rocks.
Allophanc. — Forms a thin bluish crust on limonite in veins
near Bergen ranch, Bergen Park.
Amazonstonc. — On Elk Creek and near the mouth of Tar-
ryall Creek, with smoky quartz and gothite.
Analdte. — Pure white or transparent crystals in the basalt
of North Table Mountain, associated with other zeolite min-
erals. Specially abundant on the east side of the mountain.
Small crystals abundant on South Table Mountain.
12 Jefferson Coimty Minerals.
Apophyllite. — Well developed crystals of prismatic habit on
North Table Mountain. The larger crystals are usually ter-
minated by a number of small pyramids.
Aquamarine. — Small inferior specimens on Tiffany ranch,
Bear Creek.
Aragonite. — Occurs in a vein at Golden Gate.
Asphaltum (bitumen, mineral pitch). — Forms crusts on
sandstone near Morrison.
Attgite. — An essential constitiient of the augite-andesite
rocks of Green and Table Mountains.
Azurite (blue carbonate of copper.) — Occurs as an incrus-
tation and minute crystals in the copper veins, Bear Creek.
Beryl. — Abundant on Bear Creek and in Bergen Park.
Crystals vary in size from small ones to those two feet in di-
ameter. Translucent and good color specimens rare.
•Biotite (black mica). — A constituent of much of the gran-
ite and dike rocks.
Bismutite (carbonate of bismuth). — In the Bismuth Queen
vein on Guy Hill.
Bismuthinite (sulphuret of bismuth). — Associated with bis-
mutite in the Bismuth Queen lode, Guy Hill.
Bole (iron clay). — Occurs as a dark brown clay on South
Table Mountain.
Brown Coal (lignite). — Extensive veins at Golden, on Ral-
ston Creek, and other localities.
Calcite (carbonate of lime). — Large masses of cleaveable
white calcite on Bear Creek.
Cairngorm (smoky quartz.) — On Elk Creek and near the
mouth of Tarryall Creek, with amazonstone and gothite.
Carnelian. — Small pieces of red and yellow carnelian on
Green Mountain.
Chabasite. — Abundant in small crystals in the basalt of
North Table Mountain.
Chalcedony. — Sparingly on Green Mountain and vicinity.
Chalcedony x. — Sparingly between the mountains and Den-
ver.
Chalcocite (copper glance, sulphuret of copper). — In copper
lodes on Bear Creek, in Bergen Park, and near Golden.
Chalcopyrite (copper pyrites). — In the mineral veins on
Bear Creek and in Bergen Park.
fefferson County Minerals. /j
Chlorophane (green fluor spar). — Abundant in many veins
on Bear Creek.
Chrysocolla (silicate, of copper).— Sparingly in the copper
veins on Bear Creek and in Bergen Park.
Cohimbite. — In small masses 011 Turkey Creek. Analysis
shows the mineral to contain a small amount of tin and n
per cent of manganese.
Cuprite (red oxide of copper). — In copper veins in Bergen
Park and on Bear Creek.
Enstatite. — An accessory mineral of a -dike of diabase at
Morrison.
Epidote. — Massive and crystallized in the granitic rocks.
Quite pretty crystals are found on Bear Creek.
Fluorite (fluor spar). — Massive, purple, green and white,
in veins on Bear Creek. Purple near the mouth of Tarry all.
Massive on Cub Creek.
Galenite. — Abundant in many of the veins on Bear Creek.
Garnet. — Iron garnets are quite common in Bergen Park.
Gothite. — On Elk Creek and near the mouth of Tarry all
Creek, with amazonstone and smoky quartz.
Gypsum. — Abundant in Jurassic shale near Morrison.
Hematite. — An earthy red hematite at Morrison.
Henlandite. — Small colorless tabular crystals in the augite-
andesite of Green Mountain.
Hornblende. — Of general occurrence in the archsean rocks.
Iceland Spar. — Small yellowish masses in the amygdaloid
of the Table Mountains.
Jasper. — Red and yellow jasper in the Green Mountain
region.
Kaolinite (porcelain clay). — Extensive beds at Golden.
Laumontite. — Occurs as a reddish-yellow sand-like material
and in compact masses in the basalt of North Table Mt.
Lepidomelane (iron potash mica). — A constituent of some of
the granite.
Levynite. — Of rare occurrence in small white and colorless
crystals associated with other zeolites on North Table Mt.
Limonite. — Small masses in the veins of Bergen Park.
Magnetite (magnetic iron). — An accessory mineral of much
of the granite. Loose crystals in the soil on Bear Creek and
in Bergen Park.
14 Jefferson £onnty. Miner alsi ..-.:.
Malachite (green carbonate of copper). — Occurs as a stain
or incrustation at the surface of many of the copper veins in
Bergen Park and on Bear Creek.
Mesolite. — Occurs as exceedingly delicate needles in the
basalt of North Table Mountain.
Microcline. — Near the mouth of Tarryall Creek, with ama-
zonstone, smoky quartz, gothite and fluorite.
Mineral Resin. — Small specimens of an undetermined va-
riety of resin in the soil on South Table Mountain and in the
coal veins.
Molybdenite. — Occurs as an associate of bismuth minerals
on Guy Hill.
Muscovite, (common mica). — Common in archaean rocks,
Large deposits on Deer Creek, where some mica mining has
been done.
Native Alum. — In Jurassic shale on Bear Creek near Mor-
rison, and between Morrison and Platte Canon.
Native Copper. — In considerable quantities in copper lodes
near Golden. Small specimens in the lodes on Bear Creek
and in Bergen Park.
Native Gold. — In the alluvium of Clear Creek.
Native Sulphur. — In small crystals. Exact locality not
known.
Natron (carbonate of soda). — As crusts and in solution in
the waters of the lakes between Turkey and Bear Creeks.
Natrolite.- — Occurs as delicate prisms sparingly deposited
on analcite or associated with that mineral in the basalt of
South Table Mountain. Less frequently on North Table Mt.
Oligoclase (aventurine feldspar). — A constituent of much of
the archaean rocks.
Orthoclase (common feldspar). — The most abundant con-
stituent of the archaean rocks.
Petroleum. — Oozes from Cretaceous sandstone at Morrison.
Plagioclase. — An essential constituent of diabase from Mor-
rison, in which it occurs in narrow prisms.
Ptilolite (new). — A new zeolite described by Whitman Cross.
Occurs in small white tufts in the augite-andesite of Green
Mountain. Sparingly with other zeolites on the Table Mts.
Pyrite (iron pyrites). — Small quantities in the veins of
Bergen Park and on Bear Creek.
Jefferson County Minerals. 75
Pyroxene. — An essential constituent of diabase from a dike
near Morrison.
Quartz. — Large veins and masses of white quartz in Bergen
Park, on Bear Creek, and in the Guy Hill region.
Rock Crystal. — Colorless quartz in crystals abundant on
the divide between Deer and Elk Creeks.
Rose Quarts. — In large masses in Bergen Park.
Satin Spar (var. gypsum). — Abundant in Jurassic shales
near Morrison.
Scolecite. — Occurs sparingly in spheres with a radiate struct-
ure in the basalt of North Table Mountain.
Selenite (gypsum). — In Jurassic shale near Morrison.
Silicified Wood. — On South Table Mountain. Silicified
palm wood abundant between Golden and Denver.
Stilbite. — Sparingly in small clear crystals with other zeo-
lites on North Table Mountain.
Thenardite (sulphate of soda). — Occurs in quantity at Burd-
sall's lake near Morrison.
Thomsonite. — In the basalt of North Table Mountain in
minute rectangular blades which are placed like a closed fan,
and in spherical concretions having a radiate structure.
Tourmaline. — Fine black crystals in quartz on Bear Creek.
Near the head of Ralston Creek.
Jefferson County is also accredited with the following min-
erals, btit their occurrence needs verification :
Aluminite, Mt. Vernon.
Antrimolite, Table Mountains.
Egeran, Gennessee ranch on Bear Creek.
Idocrase, Bear Creek.
Pyrrhotite.
Wavellite, Table Mountains.
Wheelerite, in the coal.
Topazolite, Malachite lode, Bear Creek.
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