Original paper

Mineralogical study of precolonial (16501850 CE) tin smelting slags from Rooiberg, Limpopo Province, South Africa

Heimann, Robert B.; Chirikure, Shadreck; Killick, David

Abstract

Vitreous slag remains of prehistoric tin smelting activities (1650-1850 CE) excavated at Rooiberg, Limpopo Province, South Africa were analyzed by wavelength-dispersive X-ray fluorescence spectrometry (WD-XRF), energy-dispersive X-ray spectroscopy (EDX), and electron-microprobe analysis (EPMA). The slags were found to contain high concentrations of tin oxide suggesting a low level of metal recovery that resulted in substantial tin losses. In addition, skeletal cassiterite, and complex spinels, as well as tin prills ranging in size from a few to tens of micrometres were observed. The contribution discusses the role tin(II) and (IV) oxides are thought to play during formation of slag as well as the crystal chemistry of spinels precipitated during cooling.

Keywords

cassiterite oretin-bearing glassesspineltin smelting technologyslag