Smaltite

Smaltite is a variety of the mineral skutterudite consisting of cobalt iron nickel arsenide: (Co,Fe,Ni)As₂.

Smaltite crystallizes in the cubic system with the same hemihedral symmetry as pyrite; 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 color is tin-white to steel-grey, with a metallic luster; the streak is greyish black. Hardness is 5.5 and the specific gravity is 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).