Mineral phase
IMA name
Donpeacorite
Type
Class
silicate mineral
Compound type
inosilicate
Comments
Donpeacorite: name by extension of $(Fe,Mn,Mg)_2Si_2O_6$ in the range Fe=0-10%, Mn>10% - Mass, density and optical properties for $Mn_{0.5}Mg_{1.5}.[SiO_3]_2$ (x=0.5)
Chemical composition
Formula
$(Mn^{2+}_x,Mg_{1-x})Mg.[SiO_3]_2 \ \ \ \ \ $ where $x=0-1$
Chemical formula
(Mn2+,Mg)MgSi2O6
Elemental formula
(Mn2+)0-1 (Mg)1-2 Si2 O6
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Mn^{2+}$ Manganese(II) cation element 0 - 1 constituent element main
$Mg$ Magnesium element 1 - 2 constituent element main
$Si$ Silicon element 2 constituent element main
$O$ Oxygen element 6 constituent element main
Composition comments
Common substitution: $Fe^{2+}$ - Common impurities: Al, $Fe^{3+}$, Ca, Na
Oxides
Formula $MnO$ $MgO$ $SiO_{2}$
Mass fraction (%) 23.78 22.52 53.71
Oxides comments
for $Mn_{0.5}Mg_{1.5}.[SiO_3]_2$ (x=0.5)

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)
Code
65.01.02.03
Phase type
crystalline
Crystal system
orthorhombic
Crystal class
dipyramidal
Crystal class symbol
mmm (D2h)
Crystal spacegroup
Pbca
Molar mass
200.78 - 231.41 $g/mol$
Density
3.36 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.015
Refraction index $n_{\alpha}$
1.677
Refraction index $n_{\beta}$
1.684
Refraction index $n_{\gamma}$
1.692
Dispersion V
weak
Pure color
yellow
Color
yellow-orange
Diaphaneity
transparent to translucent
Luster
vitreous
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