Hypersthene

Orthopyroxene of this composition is a common component of igneous rocks such as pyroxenite, andesite and basalt, of charnockitic rocks and high-grade metamorphic granulites, and of some meteorites. Mindat records it from hundreds of localities, for example Wilson Lake in Labrador, Canada.

Under the 1988 pyroxene nomenclature, the enstatite–ferrosilite series has only two species, divided at the midpoint: magnesium-dominant enstatite and iron-dominant ferrosilite. Old intermediate names such as bronzite and hypersthene were dropped, so a stone sold as hypersthene can only be assigned to a species by chemical analysis. Gemdat lists a refractive index of 1.673 to 1.731 and a specific gravity of 3.45 to 3.55, higher than those of bronzite (about 1.668 and 3.35), and describes a brilliant copper-red metallic schiller on certain surfaces. Bronzite is the brown, more magnesium-rich end of the same range.

The name comes from Greek words meaning "over strength", referring to its greater hardness than hornblende, a mineral it is often confused with. The Pyroxene Subcommittee of the International Mineralogical Association's commission on mineral names discredited it in 1988 as an unnecessary name.