166 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
Red Spruce shait— The Red Spruce shaft is 90 feet deep on the Pride fault. 
It runs in ore all the way. 
Aspen Mining and Drainage tunnel, including the Copperopolis— | his tunnel runs southwest 
for 1,000 feet. Through the first 850 feet it cuts a breccia, apparently of 
glacial origin, which at first is composed principally of bowlders of red 
sandstone and blue limestone belonging to the Maroon formation, but farther 
in chiefly of gray limestone. Beyond 600 feet the bowlders of limestone 
decrease in size and are replaced by huge masses of Weber shale and lime- 
stone which have been considerably distorted. At 475 feet from the mouth 
of the tunnel a drift runs to the west 175 feet and cuts porphyry. This 
porphyry is considered the foot wall of the vein, while the hanging wall, 
which lies next it to the east, is composed of brecciated shale, porphyry, 
and black limestone. Ore has been found continuously along this zone, 
being developed by workings carried north and south. It lies in irregular 
masses, comparatively close but not always parallel to the porphyry wall. 
It is generally continuous and from 2 to 10 feet in thickness. The metallic 
sulphides occur in spaces between fragments of limestone in the crushed and 
broken zone. This breccia evidently lies along a north-south fault, extremely 
close to and dependent upon the Pride fault. The actual Pride fault, how- 
ever, is not shown in the workings. 
Little Cloud tunnel — he Little Cloud tunnel runs into the hill between the 
Pride of Aspen and A. M. and D. workings, and cuts the same fault that is 
shown in both these mines. From here it cuts a little farther west than 
does the A. M. and D. tunnel and exposes the main Pride fault with a west 
wall of blue limestone underlain by dolomite. The east wall is composed 
of very soft, compact shale and porphyry breccia. No ore has been taken 
from these workings. 
Mary B.mine—The Mary B. shaft is in shale and porphyry breccia and 
touches the gray limestone of the Maroon series. From the shaft a level 
which runs off south has struck a very heavy fault with a northeast trend, 
which separates the top of the Weber and the gray Maroon limestone on 
the northwest from the Silurian dolomite on the southeast. The junction of 
this fault with the Castle Creek fault is seen in the tunnel just under the 
old powder house in Castle Creek. Close to this fault there has been a 
slight overturning of the strata, as they were dragged along the fault plane. 
Along the fault, in the Mary B., bodies of workable ore have been discoy- 
