Constituent
Name
Mg$_{0.2}$Fe$_{0.8}$S
IMA name
Keilite
Class
non-silicate mineral
Compound type
sulfide
Constituent abundance in material
Relevance
main - major
Arrangement
single phase
Mass fraction
0.21 $\pm$ 0.05
Chemical composition
Formula
Mg$_0.2$Fe$_0.8$S
Chemical formula
Mg0.2Fe0.8S
Elemental formula
(Mg2+)0.2 (Fe2+)0.8 (S2-)
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Mg^{2+}$ Magnesium(II) cation element 0.2 1.0 constituent element main
$Fe^{2+}$ Iron(II) cation element 0.8 1.0 constituent element main
$S^{2-}$ Sulfide anion element 1 1.0 constituent element main
Composition comments
Fe is the dominant atom compared to Mg and Mn. Common impurities: Ca,Zn,Cr

Strunz

Class
sulfides - sufosalts (02)
Division
metal sulfides, M:S = 1:1 (and similar) (02.C)
Family
With Sn, Pb, Hg, etc. (02.CD)
Code
02.CD.10

Dana

Major class
sulfides (II)
Class
sulfides - including selenides and tellurides (02)
Type
where Am Bn Xp, with m:p=1:1 (02.08)
Group
Galena group (Isometric: Fm3m) (02.08.01)
Code
02.08.01.09
Phase type
crystalline
Crystal system
isometric (cubic)
Crystal class
hexoctahedral
Crystal class symbol
m-3m (Oh)
Crystal spacegroup
Fm-3m
Molar mass
81.91 $g/mol$
Refringence type
isotropic
Refringence sign
no
Color
gray
Diaphaneity
opaque
Luster
metallic