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Clinoenstatite [abbr. Cen ]

Year of discovery: 1906 (World), 1965 (Japan)

Locality list: 9 localities of clinoenstatite

• MgSiO₃
• (Mg,Fe²⁺,Ca)(Mg,Fe²⁺)Si₂O₆
• [Mg²⁺][SiO₃]^2-
• Ca/(Mg+Fe+Ca)=0-0.05, Mg(Fe+Mg)=0.5-1.0

• Class: Ca-Mg-Fe pyroxene group < Pyroxene supergroup
• Class: Inosilicate (Single chain)
• Old definition was Fe/(Fe+Mg)=0.9-1.0
• Variety: Fe/(Fe+Mg)=0.7-0.9, Clinobronzite
• Variety: Fe/(Fe+Mg)=0.5-0.7, Clinohypersthene
• Insoluble in: HCl

• Polymorph: Enstatite (Orthorhombic, Low pressure)
• Polymorph: Akimotoite (Trigonal, High pressure)

• Ca/(Mg+Fe+Ca) > 0.05: Pigeonite

• Mg => Fe: Clinoferrosilite, Ferrosilite
• Mg => Mn: Kanoite, Donpeacorite

• Si => Ti: Geikielite

• Color: Greenish brown-Colorless
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Prismatic

• Cleavage: Perfect (2 planes, 90 degree)
• Hardness: 5-6
• Density: 3.2

• System: Monoclinic
• Group: 2/m, P2₁/c
• Lattice: a=9.6, b=8.8, c=5.2, β=108.3