Essential changes in the composition of copper alloys reveal technological diversities in the transition from the Earliest Iron Age to the Early Roman period in Lithuania

Abstract

In the context of archaeometallurgical studies of copper alloys, it is relevant to record the essential changes in the elemental composition of copper alloys that occur during changes in technology and transitions in human history. This article presents the shift in the elemental composition of copper alloy from bronze-based alloys to brass ones during essential changes in archaeological material which happened at the turn of the Earliest Iron Age (500–1 BC) and the Early Roman period, from the 1st century BC to the middle of the 1st century AD. As early as the 2nd and 1st centuries BC, in the Antique world and the Roman Empire and its provinces, brass was already starting to partly replace bronze. Even if the Earliest Iron Age is the least knowable period in Lithuanian prehistory, the few pieces of jewellery attributed to this period show the changes in the composition of the copper alloy. The territorial growth of the Late Antique world and internal contacts within the Barbaricum led to the expanding strength of commodities, including raw materials, technologies, cultural ideas and ideological attitudes. Goods and ideas spread throughout the vast barbarian lands, and eventually reached the forest zone of northeast Europe. Sudden changes during the Early Roman period were first of all connected with the development of settlement structure, and this has therefore made it possible to identify some major places of the production of artefacts and partly changed directions of exchange. All this was accompanied by the emergence of new jewellery types produced by skilled jewellers according to sophisticated techniques. These changes are clearly visible in Early Roman period Lithuanian archaeological material, including the elemental composition of copper alloys. The present article uses X-ray fluorescence (XRF) spectrometry to investigate the composition of copper alloys. Radiography was used to understand the construction of artefacts, and to assess the degree of their inner corrosion and sophisticated manufacturing techniques. Solder samples were taken from the surfaces of several finds, and were analysed by qualitative microchemical analysis.