160 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
chalcopyrite. The chief ore mineral is galena, which is accompanied 
by sphalerite and a little tetrahedrite and chalcopyrite. The tetrahe- 
drite was most abundant in level 6, near the top of the ridge. It occurs 
in the lower levels, but less abundantly. The gangue of the ore is 
quartz with some barite. The quartz and galena are crystallized 
together irregularly in the larger stringers and in the main lode. A 
little native copper lias been found on level 3. The alteration of the 
wall rock adjacent to the lode is somewhat more noticeable in the 
Tiger than in the other mines of the Silver Lake Basin. A specimen 
from the south wall of level 3, about 3 feet from the main ore body, 
is a compact, light greenish-gray rock, showing indistinct traces of 
former porphyritic structure. It is traversed by numerous veinlets. 
The largest of these, about one-fourth inch wide, carries quartz, galena, 
and sphalerite. This veinlet shows comb structure, and the ore min- 
erals tend to crystallize along the medial line. Smaller veinlets con- 
sist of galena without quartz. The rock itself is thickly speckled with 
minute crystals of pyrite. Under the microscope the rock shows the 
general structure of an andesite, but no remnant of the original min- 
erals remains. The feldspars are changed to aggregates of quartz 
and sericite, and the same minerals, very finely crystalline, seem to 
compose the entire mass of the rock, exclusive of the thickly sprinkled 
pyrite. 
In the breast of the drift, level 4, the lode, which is about 4 feet 
wide, contains a dark horse-like mass. This is said to have been 4 
feet wide in places and to carry 1 to 2 ounces in gold. This material! 
shows numerous white spots, which suggest altered feldspathic pheno- 
crysts, lying in a dark-gray groundmass. The whole is mineralized, 
and contains specks of galena, sphalerite, chalcopyrite, and finely 
crystalline i^vrite. Under the microscope fragments showing the 
structure of an andesitic rock are seen embedded in a matrix of quartz 
and a very finely crystalline material, which is apparently kaolin, 
although there seems to be some sericite present also. The andesite 
fragments are altered to aggregates of these same minerals, but pre- 
serve their original porphyritic structure. The material is a much 
altered and mineralized breccia, but whether an original tuff-brecciai 
or a breccia formed during the formation of the fissure it is impossible 
to say. The lode at this point shows indications of some brecciation 
of the ore and subsequent cementation by barren white quartz. 
The Royal Tiger mine has not yet a separate mill. It is connected 
with the Iowa mine by a wire tram across the lake, and the ore is sent 
down to the Iowa mill. Although extensive work had barely begun 
in 1899, in 1900 the Royal Tiger was producing more ore than the 
Iowa. 
Buckeye mine. — This mine, situated about one-third of a mile south 
of the lake, is on the Titusville lode. Work on it was abandoned 
some years ago, but the old tunnels were being cleaned out and 
