Constituent
- Name
- Augite
- IMA name
- Augite
- Class
- silicate mineral
- Compound type
- inosilicate
- Comments
- The full Ca, ordered Orthopyroxene equivalent of Augite is the Diopside-Hedenbergite series
- Relevance
- main - major
- Arrangement
- single phase
- Abundance comments
- Low to present
- Formula
- $(Ca_x,Mg_{y1},Fe^{2+}_{y2})(Mg_y,Fe^{2+}_{1-y}).[(Si_z,Al_{1-z})O_3]_2 \ \ \ \ \ $ where $x=0.5-0.9, y1,y2=0.1-0.5, y=0-1, z=0.75-1$
- Chemical formula
- (Ca,Mg,Fe2+)2(Si,Al)2O6
- Elemental formula
- (Ca)0.5-0.9 (Mg)0-1.5 (Fe2+)0-1.5 (Al)0-0.5 (Si)1.5-2 O6
- Isotope mixture type
- terrestrial abundance
- Composition comments
- relatively low in calcium with some disorder of occupancies of Fe2+ and Mg in both octahedral sites - Common substitution: Na, Al, $Fe^{3+}$, Ti (also disordered) - Common impurities: Cr, Mn, Zn, K
- Oxides
-
Formula $CaO$ $MgO$ $FeO$ $Al_{2}O_{3}$ $SiO_{2}$ Mass fraction (%) 23.2 16.65 6.6 9.4 44.15 - Oxides comments
- For $(Ca_0.9,Mg_{0.9},Fe^{2+}_{0.2}).(Si_{1.6},Al_{0.4})_2O_6$
Strunz
- Class
- silicates (09)
- Division
- inosilicate (09.D)
- Family
- with 2-periodic single chains, Si2O6; pyroxene family (09.DA)
- Code
- 09.DA.15
Dana
- Major class
- silicates (VIII)
- Class
- inosilicate single-width unbranched chains, w=1 (65)
- Type
- with chains P=2 (65.01)
- Group
- C2/c clinopyroxenes (Ca clinopyroxenes) (65.01.03a)
- Code
- 65.01.03a.03
- Phase type
- crystalline
- Crystal system
- monoclinic
- Crystal class
- prismatic
- Crystal class symbol
- 2/m (C2h)
- Crystal spacegroup
- C2/c
- Molar mass
- 236.35 $g/mol$
- Density
- 3.19 - 3.56 $g/cm^3$
- Refringence type
- biaxial
- Refringence sign
- positive
- Birefringence
- 0.026
- Refraction index $n_{\alpha}$
- 1.680 - 1.735
- Refraction index $n_{\beta}$
- 1.684 - 1.741
- Refraction index $n_{\gamma}$
- 1.706 - 1.774
- Dispersion V
- weak to distinct (r > v)
- Color
- green, brown green, light brown, purplish brown, dark brown, black
- Diaphaneity
- translucent to opaque
- Luster
- vitreous