from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A brownish-red ferric oxide obtained as a residue after heating ferrous sulfate, used in glass polishing and as a pigment.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Polishing rouge; a reddish-brown oxide of iron, used in polishing glass, and also as a pigment; crocus Martis.
from the GNU version of the Collaborative International Dictionary of English
- n. Polishing rouge; a reddish brown oxide of iron, used in polishing glass, and also as a pigment; -- called also crocus Martis.
from The Century Dictionary and Cyclopedia
- n. The brownish-red peroxid of iron which remains after the distillation of the acid from iron sulphate.
Medieval Latin, from Spanish colcótar, from Arabic qulquṭār, possibly from Greek khalkanthos, copper sulfate : khalkos, copper + anthos, flower.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Arabic qolqotar. (Wiktionary)