(Min.) A brittle mineral of a steel-gray color and metallic luster, containing antimony, arsenic, sulphur, and nickel.
ullmannite
ullmannite
[′əl·mə‚nīt] (mineralogy) NiSbS A steel-gray to black mineral consisting of nickel antimonide and sulfide, usually with a little arsenic, occurring massive, and having a metallic luster. Also known as nickel-antimony glance.