Copper at ancient Kerma: A diachronic investigation of alloys and raw materials

This paper describes the first comprehensive study of metal artefacts found at ancient Kerma, Sudan. Covering a period of several millennia, it investigates the development of copper alloy recipes as well as metal provenance through the trace element and lead isotope ratio analysis of forty-eight sampled objects. These include grave goods as well as production waste related to large-scale bronze casting performed at Kerma. This study is part of a wider evaluation of copper alloy production at Kerma through targeted workshop excavation, materials analysis, and experimental archaeology. The analytical results illustrate the gradual and flexible transition from arsenical copper to tin bronze alloys over time, in a pattern similarly observed in ancient Egypt. Trace element distributions and lead isotope ratios for copper used at Kerma are comparable to those of contemporary Egyptian artefacts too. These findings indicate the exploitation of ores similar to those mined at the Sinai Peninsula, although copper ore deposits in Nubia remain poorly characterized and thus difficult to identify as source candidates. Nonetheless, it can be suggested that metal provisioning networks along the Nile Valley likely overlapped to varying degrees over time. These results provide an important contribution to the mapping of technological exchanges that took place between ancient Egypt and Nubia.