Constituent
Name
Orthopyroxenes
IMA name
Orthopyroxenes subgroup
Class
silicate mineral
Compound type
inosilicate
Constituent abundance in material
Relevance
impurity
Arrangement
complex intimate mix
Mass fraction
0.014 $\pm$ 0.01
Abundance comments
Mass fraction uncertain (0.014 for < 2µm size - Vogt 2002)
Chemical composition
Formula
$(Fe^{2+}_x,Mn^{2+}_y,Mg_{1-x-y})_2.[SiO_3]_2 \ \ \ \ \ $ where $x=0-1, y=0-0.5$
Chemical formula
(Fe2+,Mn2+,Mg)2Si2O6
Elemental formula
(Fe2+)0-2 (Mn2+)0-1 (Mg)0-2 Si2 O6
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Fe^{2+}$ Iron(II) cation element 0 - 2 constituent element main
$Mn^{2+}$ Manganese(II) cation element 0 - 1 constituent element main
$Mg$ Magnesium element 0 - 2 constituent element main
$Si$ Silicon element 2 constituent element main
$O$ Oxygen element 6 constituent element main
Composition comments
Common impurities: Al, $Fe^{3+}$, Ca, Na, K, Co, Ni, Mn, Ti, Cr
Oxides
Formula $FeO$ $MnO$ $MgO$ $SiO_{2}$
Mass fraction (%)

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)
Phase type
crystalline
Crystal system
orthorhombic
Crystal class
dipyramidal
Crystal class symbol
mmm (D2h)
Crystal spacegroup
Pbca
Molar mass
200.78 - 263.86 $g/mol$
Density
3.10 - 4.02 $g/cm^3$
Refringence type
biaxial
Refringence sign
positive or negative
Birefringence
0.009 - 0.021
Refraction index $n_{\alpha}$
1.650 - 1.767
Refraction index $n_{\beta}$
1.652 - 1.770
Refraction index $n_{\gamma}$
1.659 - 1.788
Dispersion V
weak to strong (r < v)
Color
colorless, white, greenish white, yellowish green, yellow orange, green, gray, brown, dark brown, black
Diaphaneity
transparent to opaque
Luster
vitreous