Orthopyroxene subgroup

Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite (MgSiO3) – ferrosilite (FeSiO3). The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. The intermediate composition, , has historically been known as hypersthene, although this name has been formally abandoned and replaced by orthopyroxene. When determined petrographically or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite (Fs) (e.g., En80Fs20).

thumb|Bronzite variety from the Bare Hills copper mine, Baltimore County, Maryland, USA (size: 9.6 x 7.5 x 4.9 cm) thumb|Bronzitite, thin section of a rock made of olivine and pyroxene, mostly bronzite. Photomicrograph, viewed with polarized light.