Mineral phase
- IMA name
- Enstatite-Ferrosilite series
- Class
- silicate mineral
- Compound type
- inosilicate
- Formula
- $(Ca_y,Fe^{2+}_x,Mg_{1-x-y})_2.[SiO_3]_2 \ \ \ \ \ $ where $x=0-1, y<0.05$
- Chemical formula
- (Ca,Fe2+,Mg)2Si2O6
- Elemental formula
- (Ca)0-0.1 (Fe2+)0-2 (Mg)0-2 Si2 O6
- Isotope mixture type
- terrestrial abundance
- Composition comments
- perfect solid solution - Common impurities: Al, $Fe^{3+}$, Na, K, Co, Ni, Mn, Ti, Cr - Hypersthene is old name for mid-way member between Enstatite and Ferrosilite - C
- Oxides
-
Formula $CaO$ $FeO$ $MgO$ $SiO_{2}$ Mass fraction (%) - Oxides comments
- CaO from 0 to 2.77%, FeO from 0 to 54.45%, MgO from 0 to 40.15%, SiO2 from 45.55 to 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)
- End-members
- Members
-
- Enstatite (Fe = 0-50%, Mg = 100-50%, Ca < 5%)
- Hypersthene (Fe = 30-70%, Mg = 70-30%, Ca < 5%)
- Ferrosilite (Fe = 50-100%, Mg = 50-0%, Ca < 5%)
- 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 $g/cm^3$
- State NTP
- solid
- Refringence type
- biaxial
- Refringence sign
- positive
- 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)
- Pure color
- various
- Color
- colorless, white, greenish white, yellowish green, green, gray, brown, dark brown, black
- Diaphaneity
- translucent to opaque
- Luster
- vitreous