SMALTITE  , a

mineral consisting of cobalt diarsenide (CoAs2) . It crystallizes in the cubic system with the same hemihedral symmetry as pyrites; crystals have usually the form of cubes or cubo-octahedra, but are imperfectly developed and of some-what rare occurrence . More often the mineral is found as compact or granular masses . The colour is tin-white to steel-grey, with a metallic lustre; the streak is greyish black . Hardness 51; specific gravity 6.5 . The cobalt is partly replaced by iron and nickel, and as the latter increases in amount there is a passage to the isomorphous species chloanthite (NiAs2) . It occurs in veins with ores of cobalt, nickel, copper and silver: the best known locality is Schneeberg in Saxony . The name smaltite was given by F . S . Beudant, in 1832, because the mineral was used in the preparation of smalt for producing a blue colour in porcelain and glass . (L . J .