What is "tellurobismuthite"

n. (context mineralogy English) A soft dull grey mineral form of bismuth telluride.

Tellurobismuthite is a telluride mineral: bismuth telluride ( Bi Te). It crystallizes in the trigonal system. There are natural cleavage planes in the (0001) direction as the crystal is effectively lamellar (layered) in that plane. The Mohs hardness is 1.5 - 2 and the specific gravity is 7.815. It is a dull grey color, which exhibits a splendent luster on fresh cleavage planes.