Colors with Undefined Names

9. Caput Mortuum Color 146 - #592720

In alchemy, Caput Mortuum (alternately called nigredo) signified a useless substance left over from a chemical operation such as sublimation and the epitome of decline and decay; alchemists represented this residue with a stylized human skull, a literal death's head. The symbol shown on this page was also used in 18th century chemistry to mean residue, remainder, or residuum. Caput mortuum was also sometimes used to mean crocus metallorum, i.e. brownish-red metallic compounds such as crocus martis (ferrous sulphate), and crocus veneris (copper oxidule).

Caput mortuum (variously spelled caput mortum or caput mortem), also known as Cardinal purple, is the name given to a purple variety of haematite iron oxide pigment, used in oil paints and paper dyes. It was a very popular colour for painting the robes of religious figures and important personages (e.g. art patrons).