384 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
quartz occurs to the southwest of this vein, with about parallel strike. A cross vein 
carrying fluorite intersects the main vein about 300 feet north of the vertical shaft. 
The principal ore shoot began at the mouth of the incline shaft and extended 
southwesterly for 180 feet. It pitched to the southwest on the plane of the vein 
and crossed the vertical shaft at about the 06-foot level. At 140 feet the size and 
value of the ore body was very much diminished, but some work continued below 
that point. No ore was found below the 250-foot level. The richest part of the 
shoot occurred 125 feet below the surface, where the ore body was 25 feet wide and 
about 120 feet long. In most places the ore is about 4 feet thick. A small body 
of ore was taken out at the intersection of the main vein and the fluorite vein above 
the 173-foot level. 
The ore was oxidized in all places except a small core where the ore body had 
its greatest width and where calaverite appeared. The value of the ore was high, 
running up to 76 ounces per ton. A 300-ton lot of 10-ounce ore was shipped at one 
time. 
BLOCK 8, SCHOOL SECTION 16. 
The tract of State land known as block 8, school section 16, is situated on the 
lower slope of Bull Cliff, near Grassy Creek, and east of Cameron. A lease on the 
property is being worked by La Montaigne Brothers, who in two and a half years 
have taken out about $85,000, which represents the total production of the mine. 
A shaft 550 feet deep has levels turned from the 250, 350, and 550 foot points, 
the total development amounting to nearly 3,000 feet. < 
The principal rock of the mine is characteristic breccia, frequently pinkish or 
reddish, with remarkably little pyritization and alteration. In places, however, it 
is gray and more compact and can not always be easily distinguished from massive 
rock. Two basaltic dikes are exposed on the surface and appear in the underground 
workings. One of them, with a northeast strike, and dipping steeply northwest, 
passes about 150 feet east of the shaft. It can be traced down the hill to the creek 
and up the hill to the Isabella mine and corresponds in appearance to the dike seen 
there, being fresh and black, with noticeable phenocrysts of pyroxene. It is a 
trachydolerite and is 8 to 15 feet wide. The workings underground show that the 
course of the dike is not constant. It appears to veer more to an east-west course 
with increasing depth. 
The other dike, which is seen about 75 feet north of the shaft, has an east- 
northeast course and a dip which is on the whole about 85° S., though it is slightly 
inclined here in one direction, there in the other direction, from the vertical. This 
rock is more decomposed, but where fresh is a dense black aphanitic rock, which the 
microscope shows to be probably in the class of monchiquites. 
The crossing of these two dikes is not seen on the surface, but as they dip together 
the intersection is exposed on the 250-foot and again on the 450-foot level, and in 
both places the east side of the smaller dike is faulted about 10 feet to the north by 
the larger. This narrow basalt dike seems to have been intruded along a fissure 
earlier filled by a latite-phonolite dike. The width of the latite-phonolite is not 
