Constituent
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
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ca$ Calcium element 0.5 - 0.9 constituent element main
$Mg$ Magnesium element 0 - 1.5 constituent element main
$Fe^{2+}$ Iron(II) cation element 0 - 1.5 constituent element main
$Al$ Aluminium element 0 - 0.5 constituent element main
$Si$ Silicon element 1.5 - 2 constituent element main
$O$ Oxygen element 6 constituent element main
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
Inosilicates 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