Cemented ash as a receptacle or work surface for ochre powder production at Sibudu,South Africa, 58,000 years ago

The white ash of Sibudu hearths sometimes became cemented and, when this was the case, some of these crusts were used as work surfaces or receptacles, particularly in occupations dating about 58,000 years ago. Substantial deposits of red and yellow ochre powder have been found on these crusts. This suggests that the ochre was not associated with hearths for heat treatment because yellow ochre readily transforms to red even at low temperatures. XRF readings suggest that the ochre used at the site derives from different geological sources. Micromorphological studies imply that phosphatization caused the cementation of the ashes in some hearths, while gypsum growth hardened one of the hearths described here.