204 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
The concentrates rarely exceed $4 or $5 per ton of ore. The tailings 
from the main mill average from $3 to $5 per ton. They were formerly 
treated in a small auxiliary mill fitted with Wilfley tables. A cyanide 
plant was, however, nearly completed in 1900, and will treat the slimes 
directly from the mill. Power for the main mill is supplied by a 
Pelton water wheel or a 75-horsepower engine. The full capacity 
with 40 stamps is about 130 tons. 
Hidden Treasure mine. — This mine, just north of the Cami) Bird, 
was opened in 1875, but, like other properties in Imogene Basin, has 
lain idle for man}' years. It is now owned by Mr. Walsh, and will 
probably be again worked. It has at present about 2,000 feet of 
drift, and has x^roduced some ore from its s topes. It is opened by 
a crosscut tunnel about 150 feet in length. The lode strikes about 
N. 50° W. and dips northeast at approximately 60°. It is a regular 
lode, in part occupying a sheeted zone and in part a solid vein of 
quartz and ore. The country rock is San Juan breccia. There has 
been some later movement along the plane of the vein, as shown by 
thin clay gouges. The ore formerly extracted is said to have con- 
sisted chiefly of galena and tetrahedrite, and to have contained 100 
ounces of silver and 42 per cent of lead. The present workings show 
a low-grade milling ore consisting of galena, abundant sphalerite, 
and some chalcox)yrite and pyrite. 
Hancock mine. — This property lies just east of the present Camp 
Bird workings, and is also owned by Walsh. The lode strikes N. 55° 
W., and is very similar in general character to the Hidden Treasure. 
It joins the Camp Bird lode on the southeast. It has been idle many 
years, and is not now worked. In 1884 it was said to have furnished 
in all about 80 tons of ore, but has never been a large producer. 
Yellow Hose mine. — This is another old prospect, situated in Rich- 
mond Basin, upon which considerable work has been done. In 1881 
a "strike " of ore, consisting chiefty of galena, with chalcopyrite, pyrite, 
tetrahedrite and sphalerite, argentite, and some native silver, was 
reported on level 2, 470 feet from the entrance to the tunnel. But the 
mine has never produced much. The vein strikes N. 47° W. and dips 
NE. 65°. The ore, as seen in 1899, is low grade and very similar in 
general mineralogical character to that of the Hidden Treasure. 
U. S. Depository mine. — This mine, with the Caribou, Grand Trunk, 
and other claims, is regarded as being probably on the same vein as 
the Yellow Rose. Considerable work was done on this mine years 
ago, and in 1887 it was credited with an output of nearty $18,000, but 
it never was thoroughly successful and has been idle several years. 
A tunnel some 700 feet in length was run in from the small mill, now 
dismantled, on the road up Richmond Basin. The vein, as opened at 
this level, is in part a fairly regular sheeted zone in San Juan breccia 
and in part a less regular stringer lead. Such ore as the mine pro- 
duced came from upper workings, 400 or 500 feet higher up the slope, 
