70 SOUTHWESTERN NEVADA AND EASTERN CALIFORNIA. 
The property of the Tri-Metallic Mining Company lies one-half 
mile west of that last described. The Cambrian limestone, although 
gently flexed, is approximately horizontal. Intense staining by 
limonite is characteristic of lime-tone in the vicinity of the ore. A 
shipment of picked ore which netted $236 per ton (averaging 7 
ounce- gold. 230 ounce- silver, and L9 per cent copper) was recently 
made from a surface pocket of ore. Chalcopyrite is the only orig- 
inal sulphide present. Chalcocite, malachite, and azurite with dark- 
brown chalcedony arc secondary, and these are partially at least 
replacements of limestone. .V few masses of native copper, pre- 
sumably of secondary origin, are a bo reported, but they were not 
-ecu by tlie writer. Apparently chalcopyrite was originally distrib- 
uted in the lime-tone in masses which, so far as known, do not exceed 
one half inch in diameter. Later these scattered particles were con- 
centrated, the secondary copper mineral- apparently being replace- 
ments of lime-tone. In the main -haft bunches of chalcopyrite lie 
in the limestone in association with coarse calcite much stained by 
limonite. In some cases the chalcopyrite has been brecciated and the 
narrow interstices Idled with iron-stained chalcedony. The ore in 
this shaft i- said to have been in " kidneys." some of which were 
connected with other- by narrow seam-. From one of these masses 
1,900 pound- of ore were removed. This lens of ore, 9 feet long, was 
1 feet in diameter at the center and tapered to a point at each end. 
Ore examined from a claim owned by E. Oldt showed similar 
characteristics, a little galena and white quartz of apparently equal 
age being associated with the sulphides. Transparent drusy quartz 
crystals contemporaneous with or later than the copper and lead 
carbonate- and brown chalcedony are also characteristic. The values 
in this ore are said to be in silver and copper. 
In the Cuprite district chalcopyrite and less pyrite, galena, calcite, 
and quartz appear to have been deposited as sporadic masses in the 
limestone as seams along joints and as lens-shaped bodies along 
shear zone-. Later these ore- were altered by aqueous solutions to 
chalcocite. carbonates, and oxide-, the secondary ores in large part 
replacing lime-tone. At many points faulting accompanied or pre- 
ceded the change. Contemporaneously a much iron-stained chal- 
cedony was deposited in intimate association with the oxidized ores. 
Later, in some instances, drusy quartz was deposited upon the cop- 
per carbonates. The development is altogether too slight to deter- 
mine what part of the secondary copper ores have been concentrated 
from sulphides originally lying in limestone now removed by ero- 
sion. It is probable, however, that a considerable proportion is of 
such origin and that when the oxidized ores are worked out the cop- 
per content will decrease. It may well be. however, that the water 
level at Cuprite is deep. 
