• Webster's Revised Unabridged Dictionary
    • n Colcothar (Chem) Polishing rouge; a reddish brown oxide of iron, used in polishing glass, and also as a pigment; -- called also crocus Martis.
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Century Dictionary and Cyclopedia
    • n colcothar The brownish-red peroxid of iron which remains after the distillation of the acid from iron sulphate. It is used for polishing glass and other substances, and as a pigment under the name of Indian red. Also called chalcitis, crocus or crocus martis astringens, and caput mortuum vitrioli, or red vitriol.
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Chambers's Twentieth Century Dictionary
    • n Colcothar kol′kō-thar a dark-red iron peroxide formed by calcining copperas.
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Webster's Revised Unabridged Dictionary
NL. colcothar vitrioli, fr. Ar. qolqoṭar,


In literature:

Ferric oxide is known as colcothar, English-Roth, rouge, crocus, etc.
"Friction, Lubrication and the Lubricants in Horology" by William T. Lewis
The last polish is given by colcothar and putty.
"Popular Technology; Volume 2" by Edward Hazen