146 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
Creek and Roaring Gulch, a number of claims have been staked in that 
belt in the greenstone, a few hundred feet below the limestone, which 
seems everywhere to carry ' ' bunches " of copper ore. No development 
work has been done here, but the exposures on the faces of the green- 
stone cliffs show small ore bodies from a few inches to 2 or 3 feet in 
diameter and irregular in outline. They usually have cores of nearly 
pure bornite or chalcocite, but marginally these copper minerals 
become mingled with the surrounding greenstone as though the 
replacement had been less complete on the borders of the mass. 
In one or two instances narrow fissures from one-half inch to 1-J 
inches wide were noted which extend downward from ore pockets 
and are themselves filled with copper sulphides, but in the majority 
of cases no such connection between pocket and veinlet is to be seen. 
The most of the copper in the district is in the form of the sulphides, 
bornite, chalcocite, and chalcopyrite, but native copper also is known. 
A bowlder of the latter weighing several tons has been found in the 
gravels of Nugget Gulch, a tributary of the Kuskulana River, near 
the western end of the area; and on the upper Kotsina River several 
claims in which native copper occurs associated with other ores have 
been staked in the greenstone 4,000 or 5,000 feet below the contact 
witli the limestone. Two of these, the Keystone and the Copper 
King claims, are described here. 
Keystone claim. — Two short forks, both glacial streams, unite to 
form Kotsina River. The southern one of these drains two glaciers, 
and in a little narrow post-Glacial gorge just below the foot of the 
northernmost of these glaciers is the Keystone claim. Here in the 
wall of the canj^on, in the greenstone, are some compact quartz 
stringers and lenses, varying in width from a mere line to 5 or 6 
inches. They strike east and west and are approximately vertical. 
Epidote is associated with the quartz, sometimes in equal amount, 
as a gangue mineral in the veins. Native copper occurs in the epidote 
and in the quartz, but is more abundant in later irregular crevices 
traversing both minerals of the gangue. A small amount of chalcocite 
is present also, and in one prominent example it fills a narrow fissure 
which intersects masses of both epidote and quartz and is evidently 
later than either. 
Copper King claim. — This prospect is situated on the north side of 
the Kotsina Valley about one-fourth mile west of the Keystone claim 
and 700 or 800 feet above the river level. It consists of an altered 
belt of greenstone, in part amygdaloidal, extending several feet east 
from a well-defined north-south vertical crevice, along which there 
has probably been some movement. The greenstone within this 
altered zone has been rendered quartzose, the quartz occurring as 
si ringers and as a filling of the amygdules. The septa between the 
latter are sometimes changed to granular epidote and chlorite. 
Native copper occurs here and there in the mass in grains and 
