Of the rarer bismuth minerals we may notice the following: - the complex sulphides, copper bismuth glance or wittichenite, BiCu 3 S 3, silver bismuth glance, bismuth cobalt pyrites, bismuth nickel pyrites or saynite, needle ore (patrinite or aikinite), BiCuPbS 3, emplectite, CuBiS 2, and kobellite, BiAsPb 3 S 6; the sulphotelluride tetradymite; the selenide guanajuatite, B12Se3, Iv.
Mention may also be made here of clausthalite (lead selenide, PbSe) and altaite (lead telluride, PbTe), which, with their lead-grey colour and perfect cubic cleavage, closely resemble galena in appearance; these species are named after the localities at which they were originally found, namely, Klausthal in the Harz and the Altai mountains in Asiatic Russia.
Silver selenide, Ag2Se,.
Seleniuretted Hydrogen, H 2 Se, is obtained by the direct union of its constituent elements in the heat; by the decomposition of various selenides with mineral acids; by the decomposition of aluminium selenide, or phosphorus selenide with water; by the action of selenium on a concentrated solution of hydriodic acid; and by heating selenium with colophene (H.
Nitrogen selenide, N2Se2, is formed by the decomposition of selenium chloride with ammonia (A.