Constituent Natural ankerite Ca(Fe,Mg,Mn)(CO3)2 | SSHADE

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 and bonds

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 composition

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

Classifications

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

Crystallography

Crystal system: trigonal
Crystal class: rhombohedral
Crystal class symbol: -3 (S6)
Crystal spacegroup: R-3

Texture: polycrystalline

Physical properties

Molar mass: 200 - 209 (typical: 206) $g/mol$
Density: 3 - 3.1 $g/cm^3$

Optical properties

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