Copper sulphosalts in early metallurgy (2600–1900 BC) – chemical-mineralogical investigation of artefacts from southern Poland

Abstract

We describe a methodology of investigation of both Cu metal matrix and its mineral inclusions that aims at increasing the effectiveness of identifying the type of ore used in metal production. We point to sulphosalt ores as the main source of metal for the Final Neolithic/Early Bronze Age copper artefacts from southern Poland. The inclusions, rich in Ag, As, Sb and Sn, document the type of ore, regardless of the metallurgical process leading to depletion of As and Sb. The copper metal should contain neither Sb nor As, hence both of these elements, if originally present in ore, can be preserved only in inclusions. The concentrations of Ag, Sb, As and Sn in the artefacts investigated, the presence of inclusions, and their chemical composition, are the key indicators for the determination of the mineralogical composition of the original ores. Given the high concentrations of Sb, As and Ag in the Cu metal and mineralogy of the inclusions, the ore must have contained varying proportions of Ag-bearing tetrahedrite (Cu,Fe) 12 Sb 4 S 13 and tennantite (Cu,Fe) 12 As 4 S 13 . Mineralogical compositions of the copper ores indicate the deposits in Slovakia (Spania Dolina) as the source of metal for the artefacts investigated. The results of Pb and Cu isotopic analyses carried out for this study support those conclusions.