Chromite is a crystalline mineral composed primarily of iron(II) oxide and chromium(III) oxide compounds. It can be represented by the chemical formula of FeCr2O4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite (MgCr2O4). A substitution of the element aluminium can also occur, leading to hercynite (FeAl2O4). Chromite today is mined particularly to make stainless steel through the production of ferrochrome (FeCr), which is an iron-chromium alloy.
Octahedral chromite crystal from the Freetown Layered Complex in Sierra Leone, Africa (size: 1.3 x 1.2 x 1.2 cm)
A chromite prospect in Yukon. The black bands are chromite, which also carries platinum group metals. Gray rock is bleached ultramafics.
Bushveld Chromite
Chromitite band in chromitic serpentinite
Chromium(III) oxide is an inorganic compound with the formula Cr2O3. It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.
Chromium(III) oxide
Eskolaite mineral