Class

silicate mineral

Compound type

inosilicate

Comments

Enstatite: name by extension of $(Fe,Mg)_2Si_2O6$ in the range Fe=0-10%

Composition comments

Common substitution: $Fe^{2+}$, $Mn^{2+}$ - Common impurities: $Fe^{3+}$, Al, Ca, Na, K, Co, Ni, Mn, Ti, Cr

Oxides

Formula	$MgO$	$SiO_{2}$
Mass fraction (%)	40.15	59.85

Strunz

Class

silicates (09)

Division

inosilicate (09.D)

Family

with 2-periodic single chains, Si2O6; pyroxene family (09.DA)

Code

09.DA.05

Dana

Major class

silicates (VIII)

Class

inosilicate single-width unbranched chains, w=1 (65)

Type

with chains P=2 (65.01)

Group

Orthopyroxenes (65.01.02)

Code

65.01.02.01

Phase type

crystalline

Crystal system

orthorhombic

Crystal class

dipyramidal

Crystal class symbol

mmm (D2h)

Crystal spacegroup

Pbca

Texture

monocrystalline

Molar mass

200.78 $g/mol$

Density

3.1 - 3.3 $g/cm^3$

Refringence type

biaxial

Refringence sign

positive

Birefringence

0.009 - 0.011

Refraction index $n_{\alpha}$

1.650 - 1.668

Refraction index $n_{\beta}$

1.652 - 1.673

Refraction index $n_{\gamma}$

1.659 - 1.679

Dispersion V

weak to moderate (r < v)

Color

white, yellowish green, brown, greenish white, gray

Diaphaneity

translucent to opaque

Luster

vitreous