86 ECONOMIC GEOLOGY OF SILVEKTON QUADRANGLE, [bull. 182. 
Extension mine it has been found, scattered through masses of spongy 
quartz, as implanted crystals on the faces of quartz crystals in vugs, 
and embedded in yellow sphalerite and molybdenite. It is also some- 
times present in the ores of the Sound Democrat and Silver Queen 
mines of Placer Gulch. In the Sunnyside mine it occurs intimately 
associated with quartz, rhodonite, fluorite, yellow sphalerite, and 
galena, and has been found embedded in the latter. In the Camp 
Bird it is inclosed as small particles with galena, sphalerite, pyrite, 
chalcopyrite, and traces of some telluride, in quartz and fluorite (see 
p. 90). In the Tomboy it is found with pyrite in quartz, but only 
rarely in visible particles. Visible particles are also met with in 
bunches in the quartz in the Gold King mine. In the mines of the 
Silver Lake Basin free gold is very rarely seen, and only one specimen 
has been noted in the Royal Tiger. 
One small bunch of free gold, associated with a telluride (probably 
calaverite), has been found in the Silver Ledge mine. Rich pockets 
of free gold are reported to have been mined in early days in the 
Whale and Argentina lodes in Savage Basin, and it was the free gold 
of the Little Giant in Arrastra Gulch which in the early seventies 
first called attention to the San Juan region. 
Silver. — Isometric. Commonly filiform (wire silver). Silver white, 
but sometimes black through tarnish. Hardness, 2.5-3. Ductile and 
malleable. Specific gravity, 10.1-11.1. 
Native silver is very rarely seen in the ores worked at the present 
day. But in the form of wire silver it was formerly found in the 
Pride of the West, Aspen, Ben Franklin, and Sunnyside Extension 
mines. It occurs occasionally in the Aspen and in the Antiperiodic 
mines, and, as small hackly particles and plates solidly embedded in 
limestone (probably Devonian), on the Fairview claim on Sultan 
Mountain. It is probably in all cases of secondary origin, resulting 
from the oxidation of other silver minerals. 
Copper. — Isometric. Occurs in irregular plates and branching 
forms. Copper red. Ductile and malleable. Hardness, 2.5-3. Spe- 
cific gravity, 8.8-8.9. 
Occurs in small amounts in the Royal Tiger, Tom Moore, and Sunny- 
side Extension mines. It is confined, as far as known, to the superficial 
portions of the lodes and is of later formation than the bulk of the 
ore. In the Tom Moore it occurs in a stringer of quartz which con- 
tains small ciystals of hiibnerite and cuts the ore. 
Hi'ibnerite. — Tungstate of manganese (MnW0 4 ), usually with some 
iron. Monoclinic. One perfect cleavage. Usually in bladed prisms; 
often radial. Brownish red to black. Luster, submetallic or metallic- 
adamantine. Hardness, 5-5.5. 
This mineral occurs rather widely distributed over the Silverton 
quadrangle as a vein mineral associated with quartz and fluorite. It 
is most abundant at the Adams lode on Bonita Mountain, where it 
forms striking radial clusters of brownish-red crystals embedded in 
