168 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
bearing zinc blende or black jack, and pyrrhotite. The latter mineral 
was tested for nickel and cobalt, neither of which was found to be 
present. 
The Big Horn shaft is located about 600 feet from the Copper Queen 
opening, in a direction S. 20° E. The country rocks are a schistose 
diorite, which breaks up into pencils or rod-like pieces instead of 
platy fragments and ordinary schist. The pencil structure is pro- 
duced by cleavage in two directions — N. 80° E. and N. 10° W. — the 
former being somewhat the more prominent.' A nearly horizontal 
rifting is noticeable both in the surface outcrops and in the mine 
workings. At the Go-foot level a drift 25 feet in length, running 
toward the southeast, shows a vein of hornblende gangue, carrying 
chalcopyrite in varying amounts. 
The width of the vein varies from 18 to 36 inches, but it is not con- 
tinuous toward the northwest, and it appears to be a lenticular segre- 
gation conformable to the structure of the country rock, which strikes 
N. 80° W. at the end of the drift, with a nearly vertical dip. The 
vein matter sometimes incloses fragments of the country rock, and 
while the ore occurs largely intercrystallized with the hornblende, it 
also impregnates the country rock to a distance of 2 or 3 feet. At 
the bottom of the shaft a mass of quartz occurs, about 30 inches 
across, which appears to cross the trend of the country rock. The 
formation of this quartz is probably distinct from that of the horn- 
blende, since the latter contains little or no quartz. 
Grand Republic. — This property is located about 3 miles southeast 
of the Big Horn. Here the country rock is made up of alternating 
zones of granite and diorite, each of varying composition. The loca- 
tion seems to have been made on a 3-foot vein of vitreous quartz 
carrying some fresh chalcopyrite. This vein follows the direction of 
the bands in the gneiss, or about N. 30° E, and dips 20° SW. A short 
distance east of the vein there is a metamorphosed zone in the diorite, 
in which a great deal of massive epidote has been developed. Though 
in a very different rock, this zone recalls the metamorphosed volcanic 
rocks occurring at the Verde mine in the Encampment region. 
The variations in the country rock at this place are extreme. Cer- 
tain light-colored bands are so siliceous that upon first sight they have 
the appearance of quartzites, while other bands of diorite are nearly 
black and contain only a very small amount of light-colored minerals. 
Between these two extremes all intermediate types occur. 
The development shaft, which has been sunk to a depth of 80 feet, 
penetrates a band of black hornblende rock, but though the quartz 
vein which has been mentioned dips toward the shaft, it has not yet 
been encountered. A small amount of chalcopyrite was found in the 
shaft in a massive segregation of hornblende, and a specimen taken at 
the bottom shows a small lens of glassy quartz surrounded by dark- 
green hornblende, with chalcopyrite disseminated throughout the 
