Bismuthinite is a mineral consisting of bismuth sulfide (Bi<sub>2</sub>S<sub>3</sub>). It is an important ore for bismuth. The crystals are steel-grey to off-white with a metallic luster. It is soft enough to be scratched with a fingernail and rather dense.
Bismuthinite forms a series with the lead, copper, bismuth mineral aikinite (PbCuBiS<sub>3</sub>).