The Collaborative International Dictionary of English v.0.48:

Hypersthene \Hy"per*sthene\ (h[imac]"p[~e]r*sth[=e]n), n. [Gr.
   "ype`r over + sqe`nos strength: cf. F. hyperst[`e]ne.] (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.
   [1913 Webster]