Slag identification at Southern African archaeological sites

Slags and slag-like materials are ubiquitous components of southern African Iron Age sites. Their correct identification is crucial to understanding technological processes performed at these sites. This paper presents criteria for distinguishing between iron smelting slags, iron forging slags, copper smelting slags, crucible slags resulting from melting activities, vitrified clay and various biomass materials. Slag identification should entail a combination of morphology, microscopic study, chemical analysis, and assessment of the archaeological context. It is a necessarily specialist activity and superficial classification without materials analysis can be misleading. Archaeologists need to be mindful of both the archaeological opportunities and the potential technical difficulties in the interpretation of slags.