Hypersthene

Hy″per‐sthene (hī″pẽr‐sthēn), n. [Gr. υπἕρ over + σθένοσ strength: cf. F. hyperstène.] (Min.) An orthorhombic mineral of the pyroxene group, of a grayish or greenish black color, often with a peculiar bronzelike luster (schiller) on the cleavage surface.