Hy"per*sthene (hī"p&etilde;r*sthēn), n. [Gr. "ype`r over + sqe`nos 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.