Mineral phase
IMA name
Akermanite
Type
Class
silicate mineral
Compound type
sorosilicate
Chemical composition
Formula
$Ca_2Mg(Si_2O_7)$
Chemical formula
Ca2MgSi2O7
Elemental formula
Ca2 Mg Si2 O7
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ca$ Calcium element 2 constituent element main
$Mg$ Magnesium element 1 constituent element main
$Si$ Silicon element 2 constituent element main
$O$ Oxygen element 7 constituent element main
Oxides
Formula $CaO$ $MgO$ $SiO_{2}$
Mass fraction (%) 41.14 14.78 44.08

Strunz

Class
silicates (09)
Division
sorosilicate (09.B)
Family
Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination (09.BB)
Code
09.BB.10

Dana

Major class
silicates (VIII)
Class
sorosilicate Si2O7 groups, generally with no additional anions (55)
Type
with cations in [8] and lower coordination (55.04)
Group
Melilite group (55.04.01)
Code
55.04.01.01
Phase type
crystalline
Crystal system
tetragonal
Crystal class
scalenohedral
Crystal class symbol
-42m (D2d)
Crystal spacegroup
P-42(1)m
Molar mass
272.63 $g/mol$
Density
2.944 (calc.: 2.94) $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
positive
Birefringence
0.008
Refraction index $n_o$ (w)
1.632
Refraction index $n_e$ (e)
1.640
Pure color
colorless
Color
colorless, grayish, green, brown.
Diaphaneity
transparent to translucent
Luster
vitreous
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