Constituent
Name
Orthopyroxenes
IMA name
Orthopyroxenes subgroup
Class
silicate mineral
Compound type
inosilicate
Comments
from Vogt et al. (2002)
Relevance
impurity
Arrangement
unknown
Mass fraction
1.0 ± 0.001
Formula
(Fe2+x,Mn2+y,Mg1xy)2.[SiO3]2      where x=01,y=00.5
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
Fe2+ Iron(II) cation element 0 - 2 constituent element main
Mn2+ 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, Fe3+, Ca, Na, K, Co, Ni, Mn, Ti, Cr
Oxides
Formula FeO MnO MgO SiO2
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/cm3
Refringence type
biaxial
Refringence sign
positive or negative
Birefringence
0.009 - 0.021
Refraction index nα
1.650 - 1.767
Refraction index nβ
1.652 - 1.770
Refraction index nγ
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