For serious discussion of the controversies, approaches and enigmas surrounding the origins and development of the human species and of human civilization. (NB: for more ‘out there’ posts we point you in the direction of the ‘Paranormal & Supernatural
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Please do so. On p. 348 Lucas/Harris are listin natural ochre deposits from which the best quality red was obtained.
Nicholson/Shaw (Ancient Egyptian Materials and Technologies) have their "painting materials"-section totally in part 1: "inorganic materials". About the chemical structure they come to the same conclusions than Lucas/Harris: Inorganic ochre (p. 113/4)
There is nothing to date.