35.—Gray Copper Ore.
Occurs in crystallized or granular masses; metallic lustre; color between steel-gray and iron-black; brittle; the powder dissolved in nitric acid makes a brownish green solution; melts at a red heat; gravity 5.
Value.—An ore of copper, (containing thirty-three per cent.) and silver, of which Nevada specimens have sixteen per cent.
Localities.—Found with gold, silver and lead. Kellogg Mines, Ark.; Mariposa and Shasta Counties, Cal.; Sheba and De Soto Mines, and near Austin, Nev.; Heintzelman and Santa Rita Mines, Arizona.