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: Fe2O3
Systematic name: iron (III) oxide
ferric oxide in American English
a brown or reddish oxide of iron, Fe2O3, occurring naturally as hematite or prepared by the oxidation of iron: used as a pigment, in polishing compounds, in magnetic tapes, etc.