The persistence of the black colour in magnetite-based pigments in prehispanic ceramics of the Argentine North-West

Abstract

The persistence of the black colour in magnetite-containing paints in polychrome ceramics of the Argentine North-West processed under conditions considered as oxidant has generated questions about ancient production technologies. In this work, the thermal oxidation reaction of magnetite to hematite under different temperatures, atmospheres and physicochemical characteristics of the materials is experimentally evaluated. The causes of this behaviour are elucidated, and it is concluded that in the archaeological context, a double-firing process was not necessary to achieve the coexistence of different colours.