bansome.] ORE MINERALS. 81 
in Maggie, Picayune, and Placer gulches, and around Mineral Point, 
lie galena sometimes occurs so minutely crystallized as to give 
merely a dark color to the quartz in which it is inclosed. This 
finely crystalline galena is often, but not invariably, highly argen- 
tiferous, as in the Sound Democrat mine in Placer Gulch. In the 
Sunnyside mine the foreman, J. James, informed me that he had 
seen free gold embedded in galena. 
Sphalerite {zinc blende).— -Zinc sulphide (ZnS). Isometric, mass- 
ve, and tetrahedral. In variously modified tetrahedral forms. Per- 
fect dodecahedral cleavage. Luster resinous. Color, various shades 
)f yellow or orange to dark brown or black. Hardness, 3. 3 to 4. Spe- 
cific gravity, 4.0. 
This is a very common mineral in this region and always accom- 
panies galena. It is not, however, worked as an ore of zinc, and 
ts presence in the ore often involves additional cost in concen- 
trating and smelting. The light-yellow varieties, commonly termed 
'rosin zinc" by the miners, are often associated with the occur- 
ence of gold. An orange or red sphalerite is common in the ores 
>f the Red Mountain range In the Yellow Jacket, a prospect on 
3ear Creek near the northern edge of the quadrangle, sphalerite 
)ccurs abundantly in a peculiar form, viz, as cylindrical aggregates 
1 radial structure, thickly embedded in a gangue of ealcite. These 
Lggregates, which occur in all sizes up to an inch or so in diame- 
er, frequently contain small specks of galena and chalcopyrite. 
Spherules of marcasite also occur occasionally embedded, like the 
Bhalerite, in the ealcite. When the ealcite is dissolved in acid 
he sphalerite remains as a loose mass of cylindrical rods lying in 
oil directions. In nearly all cases these rods are broken sections, 
s if they originally formed a loose mass of small shattered stalac- 
fees which were subsequently cemented by ealcite. 
Bournonite. — Sulphantimonite of lead and copper (3(PbCu 2 )S. 
;i>.,S.,). Orthorhombic. Steel gray, lead gray, or black. Hardness, 
:.5 to 3. Rather brittle. Specific gravity, 5.8. 
According to .Mr. S. F. Emmons's unpublished notes, this mineral 
s reported as having been found in the Yankee Girl mine. A lead- 
copper sulphantimonarsenite, probably bournonite with some arsenic 
fclacing the antimony, occurs at the Zuhi mine, in small vertically 
Mated prisms with pyrite and zunyite. 
Zinkenite.— Sulphantimonite of lead (PbS.Sb 2 S 3 ). Orthorhombic, 
>ut occurs chiefly massive. Steel gray. Hardness, 3 to 3.5. Specific 
ravity, 5.3. 
Described and analyzed by Hillebrand 1 from the Brobdignag claim, 
rtiere it is said to occur sparingly with barite. None could be seen 
: ti 1899 or 1900. 
i Mineralogical notes: Proc. Colo. Sci. Soc, Vol. I, 1884, pp. 121-123. 
Bull. 182—01 6 
