The Late Bronze Age 'metallurgists' graves’ in south-western Poland. Tracing the provenance of the metal raw material using casting moulds

•Research on casting moulds provides data on the origin of the used raw material.•Not all casting tools in the graves were used prior to deposition.•The analyses provide information on the methods of production and use of moulds.•The graves of the so-called metallurgists are a rare phenomenon.•Determining the status and social role of a metallurgist is highly complicated. A collection of objects associated with prehistoric metallurgy, including casting moulds, a casting core, and a fragment of a tuyere, were found in three metallurgists’ graves in the Late Bronze Age cemetery in Legnica, south-west Poland. The finds from these graves presented an opportunity for a scientific investigation of several aspects of Bronze Age metallurgy in this region by applying various analytical procedures to characterise the remains of metals inside the casting moulds. We also analysed metal used for the repair of one of the moulds, and the razor from one of the graves that could have been cast in a mould discovered in another grave. One of the aims of this research project was to establish a possible provenance of the metal used by the population buried in these so-called metallurgists' graves using the chemical and lead isotope analysis. The casting moulds had clear wear marks providing proof of their use. In two cases, the moulds had thick greenish-black layers possibly representing remains of a corroded metal. The chemical compositions of these layers and metal from two other artefacts was investigated using ED XRF and SEM EDS. These analyses showed the diversity of the metals used for castings. Lead isotope analyses using MC ICP MS provided information about the possible origin of lead in the remains from the moulds. The most likely source of this lead is from the ores in the Erzgebirge, in eastern Germany, a few hundred kilometres south west from the site of the graves. The provenance of lead from the razor and from the repair of the mould can be either from the Erzgebirge or Slovak Ore Mountains, or a mixture of these ores.