- a salt of chromium in the bivalent state.
- a cubic mineral, ferrous chromate, Fe3Cr2O3, usually with much of the ferrous iron and aluminum replaced by magnesium, and some of the chromium by ferric iron: the principal ore of chromium.
- a brownish-black mineral consisting of a ferrous chromic oxide in cubic crystalline form, occurring principally in basic igneous rocks: the only commercial source of chromium and its compounds. Formula: FeCr 2 O 4
- a salt of chromous acid
