caput mortuum

Etymology
.

Noun

 * 1)  Worthless residue of sublimation or distillation.
 * 2) Cardinal purple, a variety of haematite iron oxide pigment.

Etymology
lit. 'dead head'. Figurative use from alchemical literature.

Noun

 * 1) a dead man's head, a skull
 * 2) worthless residue, useless substance
 * 3) * 1591 "Caput mortuum, ut est apud Paracelsum, sign. materias, quae sunt in fundo vasis chimici" (Antonio Ricciardo, Commentaria symbolica, p. 138)
 * 4) Cardinal purple, a variety of haematite iron oxide pigment

Etymology
.

Noun

 * 1)  ; residue
 * 2) a brown-purple pigment, mainly of iron oxide
 * 3) mummy brown; a reddish-brown pigment, made from ground mummy and resin
 * 1) a brown-purple pigment, mainly of iron oxide
 * 2) mummy brown; a reddish-brown pigment, made from ground mummy and resin
 * 1) mummy brown; a reddish-brown pigment, made from ground mummy and resin