MINERALOGY-SULPHIDES AND SULPHANTIMON1TES. 
121 
mines, and it is probably entirely absent from few of the prominent veins of the 
district. The stibnite is frequently rich in gold, but this seems to be due to an 
admixture of calaverite, as was chemically proved in the case of rich stibnite from 
the C. K. & N. mine. 
Cinnabar (with native mercury).—According to Mr. Brown, an assayer at 
Cripple Creek, a little cinnabar, with some native mercury, was found in the Moon- 
Anchor vein. This is the only reported occurrence of this mineral in the district. 
The mineral was identified in the specimen. 
Galena .—In very small quantities this mineral is probably almost universally 
distributed in the ores. It is not always, however, perceptible to the naked eye. It 
has been observed with telluride ore in the Emerson and Bobtail veins of Stratton’s 
Independence mine, in the Buena Vista vein of the Isabella mine, in the Vindicator 
vein, in the Gold Coin, Dillon, Theresa, Blue Bird, Portland, Lost Anna, Anna Lee, 
Last Dollar, and Blue Bell veins; also in the rich pocket of the W. P. II. vein. 
Apparently it is rather more abundant in the western part of the district and occurs 
here in places in considerable quantity in small veins, some of which are not notably 
auriferous. Other occurrences are near the Fluorine mine on Copper Mountain, 
at several places along Spring Creek, at the Deerhorn, Ironclad, and Abe Lincoln 
mines (here coarsely crystalline), Chicago and Cripple Creek tunnel, Puzzle, Pointer, 
Midget, Conundrum, Moon-Anchor, Moose, C. K. & N., and El Paso mines. The 
mineral occurs at all depths, but within the oxidized zone is partly altered to cerus- 
site and anglesite (Penrose). The galena, while containing some silver, is not often 
strongly auriferous. 
Zinc blende {sphalerite ).—Next to pyrite, zinc blende is the most common 
metallic mineral accompanying the gold tellurides. It is probably present in every 
important vein. The mineral is usually of a reddish-brown color and occurs as 
small masses intergrown with pyrite, galena, and fluorite. It is not known to form 
distinct crystals. In fairly large quantities it was observed in the ores of the Blue 
Bell and Puzzle veins, associated with galena and covered by quartz and telluride; 
also in the Bonanza King vein of the Midget, in the Pointer, and in the lead vein of 
the Moon-Anchor. The Portland ore contains about 1 per cent of zinc blende. 
The mineral occurs at all depths, but in the oxidized zone it is usually converted 
to soluble sulphate. The dark-brown zinc blende from the Last Dollar mine con¬ 
tains, according to Hillebrand, a considerable amount of cadmium. 
Chalcopyrite .—This mineral, elsewhere so common, occurs very rarely in the 
district. It has been noted as a thin coating on tetrahedrite from Blue Bird mine. 
The few oxidized copper ores seem to be derived from tetrahedrite. 
Tetrahedrite .—This mineral, a sulphantimonite of copper, usually referred to as 
“gray copper,” is practically the only primary copper ore of the district. It gen¬ 
erally occurs in dark steel-gray masses with a reddish-brown streak, sometimes so 
red as to suggest specular iron ore. It is occasionally crystallized in tetrahedrons 
(Abe Lincoln and Doctor-Jackpot mines). It always contains silver, sometimes in 
large amounts, and most of the ore rich in silver which is shipped from the district 
carries a considerable amount of tetrahedrite. It occurs in the veins throughout 
the district and at all levels. The statement has sometimes been made that this 
mineral begins to be more abundant at a certain depth supposed to mark the 
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