Constituent
Name
Ferroan Magnesite
IMA name
Magnesite
Class
non-silicate mineral
Compound type
carbonate
Comments
Fe-rich Magnesite - previously named 'Breunnerite' with 10-30 at% Fe, and 'Mesitine Spar' with 30-50 at% Fe
Chemical composition
Formula
(Mg,Fe2+,Mn2+)CO3 with 0.05 < Fe+Mn < Mg
Chemical formula
(Mg,Fe2+,Mn2+)CO3
Elemental formula
(Mg2+)0.5-0.95 (Fe2+)0.04-0.48 (Mn2+)0-0.04 C O (O-)2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
Mg2+ Magnesium(II) cation element 0.5 - 0.95 1.0 constituent element main
Fe2+ Iron(II) cation element 0.04 - 0.48 1.0 constituent element main
Mn2+ Manganese(II) cation element 0 - 0.04 1.0 constituent element main
(CO3)2- Carbonate anion chemical function 1 1.0 anionic radical main
Composition comments
with Fe+Mn < Mg and Fe+Mn between 5 and 50% - Ca < 1%, Zn < 0.1%
Chemical functions
  Function Number
(CO3)2- 1
Chemical bonds
  Bond Number
· Mg2+ · O-- 2
……C…O-2/3 3
Oxides
Formula MgO FeO MnO CO2
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)
Code
14.01.01.02
Phase name
Ferroan Magnesite
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
R-3c
Molar mass
85.9 - 100.1 g/mol
Density
3.01 g/cm3
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.191
Refraction index nα
1.700
Refraction index nβ
1.509
Dispersion V
very strong
Color
brown, brownish yellow, gray, white
Diaphaneity
transparent to translucent
Luster
vitreous