Caput mortuum

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Alchemical symbol for caput mortuum

Caput mortuum (plural capita mortua) is a Latin term whose literal meaning is "dead head" or "worthless remains",[1] used 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.[2]

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 sulfate), and crocus veneris (copper oxidule).[3]


  1. ^ Stone, Jon R. (2005). The Routledge Dictionary of Latin Quotations. Routledge. p. 142. ISBN 0-415-96909-3. Cite has empty unknown parameter: |coauthors= (help)
  2. ^ Eastaugh, Nicholas (2004). Pigment Compendium: A Dictionary of Historical Pigments. Butterworth-Heinemann. p. 81. ISBN 0-7506-5749-9. Cite has empty unknown parameter: |coauthors= (help)
  3. ^ Liungman, Carl G. (2004). Symbols: Encyclopedia of Western Signs and Ideograms. Ionfox AB. p. 236. ISBN 91-972705-0-4. Cite has empty unknown parameter: |coauthors= (help)