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490 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
the Cashen fault. On level 7 the Cashen fault is well shown in the main east cross¬ 
cut, about 60 feet west of the Montana dike, and may also be seen in the drift follow¬ 
ing the dike. Level 8 apparently does not go far enough east to cut the fault, but it 
shows on level 9 in the main east crosscut about 35 feet east of the Coin lode and also 
in the drifts on the Coin and Spur lodes. On level 10 the fault is cut in the main 
crosscut about 90 feet east of the shaft and also near the end of a west crosscut about 
400 feet south of the shaft. At the latter place the fault is apparently represented 
by a number of nearly parallel fissures forming a zone nearly 50 feet in width. On 
level 11 the Cashen fault should be very near the main shaft, but its exact position 
was not determined. 
GEOLOGICAL FEATURES. 
The general country rock of the Gold Coin mine is the porphyritic granite which 
underlies the town of Victor and occurs in the Dead Pine, Ajax, Strong, and other 
mines in the vicinity. This is cut by several irregular dikes and sills of phonolite 
and by one small basaltic dike. The principal dike is the Montana, which is fol¬ 
lowed by the Montana lode. This dike varies in width from 10 to 40 feet. Another 
small dike, rarely over a foot in width, appears at intervals along the sheeted zone 
constituting the Dorothy lode, and a similar narrow and irregular dike of phonolite 
occurs along the No. 3 lode. 
Irregular sheets or sills of phonolite occur in several parts of the mine, and are 
usually connected with dikes. The manner in which a dike may locally turn into 
a nearly horizontal sill is well illustrated in the long west crosscut from the Coin drift, 
about 500 feet north of the shaft. Here a dike about 1 foot wide, with steep easterly 
dip, turns sharply west for about 6 feet, forming a nearly horizontal sill about 6 
inches thick. It then again bends down into a dike 16 inches in width, dipping 
steeply to the west. Another good example may be seen at the north end of level 4, 
where a dike along the Coin lode, instead of continuing down below the drift, turns 
off to the east as a flat sill. These occurrences show that the phonolitic intrusions 
in the granite are far from regular, and that it can not be assumed that either dikes 
or sills maintain their courses for long distances through unexplored ground. 
The most important phonolite sheet or sill in the mine is that exposed in level 
6, along the drift on the Spur lode. This sill, from 6 to 10 feet thick, is rolling and 
irregular, but has a gentle easterly dip which carries it about 40 feet below the level 
at the point where the main crosscut crosses the No. 3 lode. About 60 feet farther 
east, however, the top of a body of phonolite, probably an anticlinal roll of the same 
sill, is exposed in the bottom of the crosscut. Still farther east the sill probably 
connects with the Montana dike. All the phonolite seen in the Gold Coin mine is 
the usual aphanitic, greenish-gray, altered variety commonly occurring in dikes 
and sills throughout the district. 
The only basic dike seen in the mine is exposed near the face of a west crosscut 
from the north Coin drift on level 5. It is about 7 inches wide, strikes nearly north 
and south, and dips about 60° W. It is soft and decomposed and of no economic 
importance. 
The only fault of importance recognized in the mine is the Cashen fault. The 
productive lodes are generally sheeted zones showing little evidence of differential 
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