references

Credit: Portrait skull with cowrie shell eyes, Jericho, c.7th millennium BC (skull, plaster, shell), Prehistoric / Ashmolean Museum, University of Oxford, UK / The Bridgeman Art Library

 

 

"Caput mortuum is Latin for 'death's head'. The phrase, in this context, is not of Roman origin and was originally used by early seventeenth century alchemists to refer to 'worthless' residue left after experiments". Pigment Compendium, a Dictionary of Historical Pigments