Formula: Fe2+Cr2O4 multiple oxide, spinel group
Specific gravity: 4.5 to 4.8
Colour: Brownish black to iron black
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Common impurities: Mg,Mn,Zn,Al,Ti
Chromite is a common constituent of peridotite and other
mafic rocks and of
serpentine derived from them. It is one of
the first minerals to separate from a cooling magma.
Fe and Cr-rich spinel , diopside and enstatite to forsterite, anorthite and chromite
MgFeAl2Cr2O8 + CaMgSi2O6 + Mg2Si2O6 ⇌ 2Mg2SiO4 + Ca(Al2Si2O8) + Fe2+Cr2O4 This reaction occurs at fairly low temperature and pressure (DHZ 1A p233).
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