'Ullmannite' definitions:

Definition of 'Ullmannite'

From: GCIDE

Ullmannite \Ull"mann*ite\, n. [So named after J. C. Ullman, a German chemist.] (Min.) A brittle mineral of a steel-gray color and metallic luster, containing antimony, arsenic, sulphur, and nickel. [1913 Webster]