Mineral phase
IMA name
Enstatite
Class
silicate mineral
Compound type
inosilicate
Comments
Enstatite: name by extension of $(Fe,Mg)_2Si_2O6$ in the range Fe=0-10%
Formula
$Mg_2.[SiO_3]_2$
Chemical formula
Mg2Si2O6
Elemental formula
Mg2 Si2 O6
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Mg$ Magnesium element 2 constituent element main
$Si$ Silicon element 2 constituent element main
$O$ Oxygen element 6 constituent element main
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
Molar mass
200.78 $g/mol$
Density
3.1 - 3.3 $g/cm^3$
State NTP
solid
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)
Pure color
white
Color
white, yellowish green, brown, greenish white, gray
Diaphaneity
translucent to opaque
Luster
vitreous