the brownish-red oxide of iron produced by heating ferrous sulfate: used chiefly as a pigment in paints and theatrical rouge, and as a polishing agent.
Also called jewelers' rouge.
Origin
1595-1605; < Medieval Latin < Old Spanishcolcotar,Spanish Arabicqulquṭār, perhaps < Greekchálkanthos copper sulfate solution
British Dictionary definitions for colcothar
colcothar
/ˈkɒlkəˌθɑː/
noun
1.
a finely powdered form of ferric oxide produced by heating ferric sulphate and used as a pigment and as jewellers' rouge Also called crocus
Word Origin
C17: from French colcotar, from Spanish colcótar, from Arabic dialect qulqutār