ˈkälkəthə(r) noun
( -s )
Etymology: Medieval Latin, from Middle French or Old Spanish; Middle French colcotar, from Old Spanish cólcotar (now colcótar ), from Arabic dialect qulquṭār, probably modification of Greek chalkanthos — more at chalcanthite
1. : a reddish brown iron oxide left as a residue when ferrous sulfate is highly heated and used formerly in polishing glass and as a pigment
2. : a moderate reddish brown that is yellower and deeper than roan, yellower, stronger, and slightly darker than mahogany, and yellower, less strong, and slightly darker than oxblood — called also angel red, Coromandel, English red, Mars red, Prussian red, Tuscany