1911 Encyclopædia Britannica/Smaltite

by Leonard James Spencer

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 somewhat 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 5½; 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. S.)