Hypersthene
Hypersthene (hī"pẽr*sthēn) , noun
[Greek "ype`r over + sqe`nos strength: compare French hyperstène.]
(Mineralogy) 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.