Mineral phase
IMA name
Magnesite-Siderite series
Secondary names
Ferro-magnesite; Magneso-siderite; Magnesium-Iron carbonate series; Mg-Fe carbonate series
IMA Code
Mgs-Sd
Type
Class
non-silicate mineral
Compound type
carbonate
Comments
full miscibility of the solid solution
Chemical composition
Formula
$(Mg^{2+},Fe^{2+})CO_3$
Chemical formula
(Mg,Fe)CO3
Elemental formula
(Mg2+)0-1 (Fe2+)0-1 C O (O-)2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Mg^{2+}$ Magnesium(II) cation element 0 - 1 constituent cation main
$Fe^{2+}$ Iron(II) cation element 0 - 1 constituent cation main
$(CO_3)^{2-}$ Carbonate anion chemical function 1 anionic radical main
Composition comments
Mg+Fe=1
Chemical functions
  Function Number
$(CO_3)^{2-}$ 1
Chemical bonds
  Bond Number
$\cdot Mg^{2+} \cdot O^{-}-$ n
$\cdot Fe^{2+} \cdot O^{-}-$ n
$\dddot - \dddot - C \dddot - O^{-2/3}$ 3
Oxides
Formula $MgO$ $FeO$ $CO_{2}$
Mass fraction (%)

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.05

Dana

Major class
carbonates, nitrates, borates (V)
Class
anhydrous carbonates (14)
Type
with simple formula A+CO3 (14.01)
Group
Calcite group (Trigonal: R-3c) (14.01.01)
End-members
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
R-3c
Molar mass
84.31 - 115.86 $g/mol$
Density
3.00 - 3.96 $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.191 - 0.242
Refraction index $n_o$ (w)
1.700 - 1.875
Refraction index $n_e$ (e)
1.509 - 1.633
Dispersion V
very strong to strong
Pure color
colorless to yellow
Color
colorless, white, yellow, yellowish brown, brown, gray, yellowish gray, greenish gray
Diaphaneity
transparent to subtranslucent
Luster
vitreous
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