Editing Enstatite (section)

{{short description|Pyroxene: magnesium-iron silicate with MgSiO<sub>3</sub> and FeSiO<sub>3</sub> end-members}}
{{for|E-type chondrites|Enstatite chondrite}}
{{Infobox mineral
| name        = Enstatite
| category    = [[Inosilicate]]
| image       = Enstatite-202036.jpg
| imagesize   = 260px
| caption     = 
| formula     = MgSiO<sub>3</sub>
| IMAsymbol   = En<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref>
| molweight   = {{chem molar mass|Mg=1|Si=1|O=3}}
| strunz      = 9.DA.05
| system      = [[Orthorhombic]]
| class       = Dipyramidal (mmm) <br/>[[H-M symbol]]: (2/m 2/m 2/m)
| symmetry    = ''Pbca''
| unit cell   = a = 18.23, b = 8.84 <br/>c = 5.19&nbsp;[Å]; Z&nbsp;=&nbsp;8
| color       = White, grey, green, yellow or brown - colorless in thin section.
| habit       = Prismatic crystals, commonly lamellar, fibrous, or massive
| twinning    = Simple and lamellar on [100]
| cleavage    = Good/distinct on [210]
| fracture    = Uneven
| tenacity    = Brittle
| mohs        = 5 to 6
| luster      = Vitreous, pearly on cleavage
| refractive  = n<sub>α</sub> = 1.650–1.668; n<sub>β</sub> = 1.652–1.673; n<sub>γ</sub> = 1.659–1.679
| opticalprop = Biaxial (+) 
| 2V = 55–90°
| birefringence = δ = 0.009–0.011
| pleochroism = Pink to green pleochroism diagnostic for enstatite, pale green to pale orange perpendicular to pink-green axis 
| streak      = Gray
| gravity     = 3.2–3.3
| density     = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = Translucent to opaque
| other       = 
| references  = <ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/enstatite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-1384.html Mindat]</ref><ref name=Webmin>[http://www.webmineral.com/data/Enstatite.shtml Webmineral data]</ref>
}}

'''Enstatite''' is a mineral; the magnesium endmember of the [[pyroxene]] [[silicate mineral]] series enstatite (MgSiO<sub>3</sub>) – ferrosilite  (FeSiO<sub>3</sub>). The magnesium rich members of the [[solid solution]] series are common rock-forming [[mineral]]s found in [[igneous]] and [[metamorphic rock|metamorphic]] rocks. The intermediate composition, {{chem|(Mg|,Fe)|Si|O|3}}, has historically been known as [[hypersthene]], although this name has been formally abandoned and replaced by orthopyroxene. When determined [[Petrography|petrographically]] or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite (Fs) (e.g., En<sub>80</sub>Fs<sub>20</sub>).