168 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 183. 
consisting essentially of green hornblende and quartz. The strike of 
the schistosit} 7 is here about N. 48° E. The vein has a strike of N, 
62° W., and is practically vertical. Its average width is from 2 to 3 
feet, and it is a simple quartz-filled fissure, the vein being adherent, 
or "frozen," to the schist walls. Several tunnels have been run into 
the vein, but none of them were accessible in 1899. The only ore 
minerals seen on the dump were chalcopyrite and pyrite. According 
to Endlich, 1 of the Hayden Survey, who visited the mine in 1874, the 
width of the vein is from 4 to 5 feet, and galena and tetrahedrite formed 
the main ore, accompanied by pyrite, chalcopyrite, and sphalerite. 
The lower tunnel has a somewhat devious westerly course, and was 
designed by Edward Innis, its projector, to tap the Royal Tiger and 
other lodes of the Silver Lake Basin. It was started about 1875 and 
had reached a length of about 3,000 feet when work was abandoned 
in 1884. Several veins are said to have been cut in this tunnel, but 
none were prospected. An inspection of the dump shows that the 
whole of the tunnel is in schist. The total product of the mine was 
about 150,000. 
Toward the northwest the Highland Mary vein passes upward from 
the schists into the volcanics of the San Juan and Silverton series. 
As examined at a point 1,500 feet above the mine buildings, the lode 
in the volcanics is somewhat larger than in the schists below, having 
a width of about 12 feet. It is here composed of apparently barren 
quartz. The lode probably joins the North Star vein on the Shenan- 
doah claim. 
Green Mountain mine. — This mine, which is credited with a produc- 
tion of about $100,000, was being opened when visited by the officers 
of the Hayden Survey in 1874. In 1883 it is said to have produced 
*•■ about 300 tons of ore, averaging 38 ounces of silver and 45 per cent of 
lead per ton, valued at about $25,000. It was idle in 1899 s and evi- 
dently had not been worked for several years. The mine was opened 
through four tunnels, entering on or near the course of the lode. The 
*m\ country rock of the three lower tunnels is a rhyolitic flow- breccia. 
The upper tunnel is in Algonkian schist. The schist of course under- 
lies the rhyolite, and the fact that it is encountered in the upper 
instead of the lower workings of the mine is due to the irregularity of 
the contact between it and the younger volcanic rocks, and to the 
course of the fissure, which makes an angle with the contact. The 
strike of the lode is N. 38° W., and the general dip nearly vertical, or 
at a high angle to the northeast. In the rhyolite the vein is generally 
about 3 feet wide and is destitute of gouge. It is a simple fissure fill- 
ing, containing a few small horses of altered country rock. The ore 
contains abundant sphalerite and galena, with some chalcopyrite and 
pyrite, in a quartz gangue. In the schists the vein is from 3 to 4 feet 
wide and fills a clean-cut fissure. The quartz and ore are "frozen" 
Report on the San Juan region: Hayden Survey, 1874, p 234. 
