Pseudobrookite, Enstatite Field of view: 1.8 mm Locality: Les Châtelaunoux quarry (Petit Chambois quarry), Mazaye, Issoire, Puy-de-Dôme, Auvergne-Rhône-Alpes, F — Photo: Gianandrea Ghirri · CC BY 3.0
Enstatite
Also known as: Bronzite, Hypersthene (intermediate).
The magnesium end-member of the pyroxene enstatite–ferrosilite series — a common rock-forming mineral, and occasionally a star-stone gem.
Intro adapted from Wikipedia (CC BY-SA).
Enstatite is an IMA-recognized mineral species in the silicate class, with the chemical formula Mg₂Si₂O₆.
It crystallizes in the orthorhombic crystal system (space group Pbca). It is a member of the Pyroxene structural group.
Key properties: Mohs hardness 5–6; specific gravity 3.2–3.9; typically brown or green or gray or yellow or colorless; White to grayish streak; Vitreous to pearly on cleavages luster; refractive index 1.664; optically biaxial.
IMA symbol En, IMA status: approved, named in 1855.
Found in pyroxenites, peridotites, and dunites; in ultramafic inclusions in alkalic olivine basalts and kimberlite; in mafic volcanics, rarely in felsic volcanics. Characteristic of charnockites and the granulite metamorphic facies.
It is found associated with Olivine, phlogopite, clinopyroxene, diopside, spinel, pyrope. · ar (Zdjarberg),.
Its name comes from the Greek for opponent, in allusion to its refractory nature under the blowpipe.
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