[kol-kuh-ther] 
| 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. |
| col·co·thar (kŏl'kə-thər, -thär') n. A brownish-red ferric oxide obtained as a residue after heating ferrous sulfate, used in glass polishing and as a pigment. [Medieval Latin, from Spanish colcótar, from Arabic qulquṭār, possibly from Greek khalkanthos, copper sulfate : khalkos, copper + anthos, flower.] |