Editing Enstatite (section)

==Occurrence==
Isolated crystals are rare, but orthopyroxene is an essential constituent of various types of [[igneous rock]]s and [[metamorphic rock]]s. Magnesian orthopyroxene occurs in [[Intrusion (geology)|plutonic]] rocks such as [[gabbro]] (norite) and [[diorite]]. It may form small idiomorphic phenocrysts and also groundmass grains in volcanic rocks such as [[basalt]], [[andesite]], and [[dacite]].

Enstatite, close to En<sub>90</sub>Fs<sub>10</sub> in composition, is an essential mineral in typical [[peridotite]] and [[pyroxenite]] of the [[Earth's mantle]]. [[Xenolith]]s of peridotite are common in [[kimberlite]] and in some basalt. Measurements of the [[calcium]], [[aluminum]], and [[chromium]] contents of enstatite in these xenoliths have been crucial in reconstructing the depths from which the xenoliths were plucked by the ascending magmas.

Orthopyroxene is an important constituent of some metamorphic rocks such as [[granulite]]. Orthopyroxene near pure enstatite in composition occurs in some metamorphosed [[serpentine group|serpentine]]s. Large crystals, a foot in length and mostly altered to [[steatite]], were found in 1874 in the [[apatite]] veins traversing [[mica]]-[[schist]] and [[hornblende]]-schist at the apatite mine of Kjørstad, near [[Brevik, Norway|Brevik]] in southern [[Norway]].<ref name="EB1911"/>

Enstatite is a common mineral in meteorites. [[Crystal]]s have been found in stony and iron [[meteorite]]s, including one that fell at [[Potůčky|Breitenbach]] in the [[Ore Mountains]], [[Bohemia]]. In some meteorites, together with [[olivine]] it forms the bulk of the material; it can occur in small spherical masses, or [[chondrule]]s, with an internal radiated structure.<ref name="EB1911"/>