174 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
Pyrite occurs in all of the lodes, often intimately associated with the rich tellu- 
rides. It is sometimes supposed to be auriferous, but tests made on pyritic ores 
have in all cases shown the presence of tellurium, and careful chemical examination 
of pyrite crystals (see p. 170) has failed to detect a trace of gold. It is probable, 
therefore, that the pyrite of the Cripple Creek veins merely plays the part of a 
gangue mineral. The gold found in such pyritic ores as are stoped in the Lee and 
Lost Anna veins in the Portland mine and in the Elkton, Last Dollar, and Gold Coin 
mines probably occurs as a telluride mechanically inclosed in the pyrite. In a 
polished specimen of ore from the C. Iv. & N. mine such a relation of calaverite and 
pyrite is clearly visible (fig. 13, p. 181). 
Sphalerite, while not on the whole so abundant as pyrite, is present in nearly 
all the veins, and in some, such as the Bonanza King (Midget mine), Conundrum, 
and Lead (Moon-Anchor mine) it is found in considerable quantity. Bunches of 
galena and sphalerite in the Conundrum vein are in some cases several feet long 
and up to 6 inches wide. Usually, however, sphalerite is an inconspicuous con¬ 
stituent. The ore of the Portland mine contains about 1 per cent of zinc blende, 
and this is probably over rather than under the general average for the district. 
The distribution and occurrence of galena are much like those of sphalerite. 
Small quantities can be detected in many of the lodes, and it is probably present as 
invisible particles in others. Occasionally, as in the Pointer, Conundrum, Bonanza 
King, and Lead veins, it forms a notable proportion of the ore, which in such places 
is usually of low grade. Sporadic bunches of galena occur, however, in close asso¬ 
ciation with the rich auriferous tellurides, as in the Abe Lincoln mine. 
In addition to quartz, fluorite, dolomite, pyrite, sphalerite, and galena, which 
in varying proportions are the usual mineralogical associates of the tellurides, the 
lodes contain numerous other minerals which are less abundant. Among these are 
tetrahedrite, which has been noted in over 20 veins in the district (see p. 121), and 
molybdenite, which, while rarely conspicuous, frequently accompanies the tellurides 
and has been identified in many of the mines. Stibnite has a similar association 
with the rich ores and is probably present in small quantity in most of the promi¬ 
nent lodes. Chalcopyrite, in other regions so often accompanying pyrite, sphaler¬ 
ite, galena, and tetrahedrite, is remarkably rare in the Cripple Creek district and 
was noted only in the Blue Bird mine. Hubnerite occurs in the Puzzle vein (cut 
by the Ophelia tunnel), but, so far as known, nowhere else in the district. 
Among what are usually termed the nonmetallic vein minerals are some which, 
while not so abundant as quartz, fluorite, or dolomite, are yet characteristic of the 
Cripple Creek veins. Such a mineral is celest.ite, which has been noticed in slender 
prisms in a large number of the veins. Hollow pseudomorphs of quartz after this 
mineral are common in most of the prominent lodes. Orthoclase, as a vein mineral, 
is fairly common in the lodes, although it is especially characteristic of the meta- 
somatic ores in granite. Roscoelite occurs as a gangue mineral in the Mary McKin¬ 
ney and Ajax mines and probably elsewhere in the district. Chalcedony and opal 
are not uncommon as films and crusts lining quartzose vugs. Rhodochrosite occurs, 
so far as known, only in the Pointer, Moon-Anchor, and Fluorine mines. Calcite 
and barite, both common vein minerals in other districts, are rarely found in the 
