Constituent
Name
Natural ankerite Ca(Fe,Mg,Mn)(CO3)2
IMA name
Ankerite
Class
non-silicate mineral
Compound type
carbonate
Constituent abundance in material
Relevance
main - major
Arrangement
single phase
Mass fraction
1.0
Chemical composition
Formula
$Ca(Fe^{2+},Mg,Mn^{2+})(CO_3)_2$ with $Fe \gt Mg$
Chemical formula
Ca(Fe2+,Mg,Mn2+)(CO3)2
Elemental formula
Ca (Fe2+)0-1 (Mg)0-1 (Mn2+)0-1 C2 O6
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ca$ Calcium element 1 - 1.2 constituent element main
$Fe^{2+}$ Iron(II) cation element 0.4 - 0.7 constituent element main
$Mg$ Magnesium element 0.25 - 0.4 constituent element main
$Mn^{2+}$ Manganese(II) cation element 0 - 0.15 constituent element main
$(CO_3)^{2-}$ Carbonate anion chemical function 2 anionic radical main
Composition comments
with $Fe \gt Mg$ - Typical chemical formula: $CaFe^{2+}_{0.6}Mg_{0.35}Mn^{2+}_{0.05}(CO_3)_2$
Chemical functions
  Function Number
$(CO_3)^{2-}$ 2
Chemical bonds
  Bond Number
$\cdot Ca^{2+} \cdot O^{-}-$ 1
$\cdot Fe^{2+} \cdot O^{-}-$
$\cdot Mg^{2+} \cdot O^{-}-$
$\cdot Mn^{2+} \cdot O^{-}-$
$\dddot - \dddot - C \dddot - O^{-2/3}$ 3
Oxides
Formula $CaO$ $FeO$ $MgO$ $MnO$ $CO_{2}$
Mass fraction (%) 27.17 20.89 6.84 1.72 42.65
Oxides comments
oxydes composition corresponding to the typical chemical formula

Strunz

Class
carbonates - nitrates (05)
Division
carbonates without additional anions, without H2O (05.A)
Family
Alkali-earth (and other M2+) carbonates (05.AB)
Code
05.AB.10

Dana

Major class
carbonates, nitrates, borates (V)
Class
anhydrous carbonates (14)
Type
with compound formula A+B++(CO3)2 (14.02)
Group
Dolomite group (Trigonal: R-3) (14.02.01)
Code
14.02.01.02
Phase type
crystalline
Crystal system
trigonal
Crystal class
rhombohedral
Crystal class symbol
-3 (S6)
Crystal spacegroup
R-3
Texture
polycrystalline
Molar mass
200 - 209 (typical: 206) $g/mol$
Density
3 - 3.1 $g/cm^3$
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.18 - 0.20
Refraction index $n_{\alpha}$
1.69 - 1.75
Refraction index $n_{\beta}$
1.51 - 1.55
Color
brown, brownish yellow, gray, gray brown, greenish, white
Diaphaneity
translucent to subtranslucent
Luster
vitreous