spencer.] COPPER DEPOSITS AT PEARL, COLO. 167 
Sentry due to surface weathering of sulphide ores. The ores in the 
pegmatite are not accompanied by any contemporaneous quartz, but 
this mineral is present in small amount in the ores which occur in the 
country rock. The occurrence of ore, both in the pegmatite and in 
the inclosing rock, is very irregular, and seems to depend upon the 
fracturing which the rocks have undergone. There are two systems 
of joints, which, taken together with the gneissic structure, and with 
frequent rifts of low inclination, result in the production of angular 
blocks, by which the size and form of ore masses are often limited. 
The ore occurs, in some instances, as a probable replacement of coun- 
try rock, and in other cases as a deposit between adjacent blocks. 
The relations observed tend to show that the ores have been intro- 
duced in a manner independent of the formation of the pegmatite and 
subsequent to it. 
Gold King claims. — The workings of this property are located 
between 3,000 and 4,000 feet east of the Mount Zirkel shaft. The 
shallow openings which were visited seemed to have been located on 
carbonate stains occuring along a sheared zone in red granite. The 
heaviest stains amount almost to impregnation, and these occur at 
the intersection of closely spaced joints. In the granite near by there 
are certain bands which are very coarsely crystallized, and which 
carry red oxide of iron, probably derived from magnetite. Besides 
the large amount of granite there are also outcrops of diorite near the 
workings. 
Bound Top, Copper Queen, and Big Horn. — These claims are 
located in close proximity to one another, and distant about 3 miles 
from Pearl in a southerly direction. The surface openings which 
constitute the development of the Round Top property show the pres- 
ence of yellow sulphides and of zinc blende in a siliceous vein-like 
segregation following the banding of the gneiss, which forms the 
country rock. It seems probable that the sulphides have been intro- 
duced in the form of replacements of hornblende grains in the streaks 
in which they occur. 
On the Copper Queen claim, about 400 feet southeast of the last, the 
developments consist of a shaft about 30 feet in depth. The materials 
thrown out show the presence of a mass of hornblende rock in the 
form of a vein-like segregation in diorite-gneiss, which forms the 
country rock. Upon the immediate walls of the vein the diorite 
looks like hornblende-schist, but the microscope shows that its platy 
structure is due to recrystallization and not to crushing. It is there- 
fore concluded that the vein matter and wall rock are of the same age 
and origin. The vein matter is entirely granular and massive, in 
which respect it corresponds with other occurrences that have been 
mentioned. Along with the hornblende there is some quartz, and 
this mineral is largely confined to coarse portions of the vein, where 
calcite is also found. The metallic minerals are chalcopyrite, iron- 
