- a dark-red, crystalline, water-insoluble solid, Fe2O3, occurring naturally, as hematite and rust, or synthesized: used chiefly as a pigment, as a mordant, as a coating for magnetic recording tape, and in the manufacture of polishing compounds.
- a red crystalline insoluble oxide of iron that occurs as haematite and rust and is made by heating ferrous sulphate: used as a pigment and metal polish (jeweller's rouge), and as a sensitive coating on magnetic tape. Formula: Fe 2 O 3
