Tools and jewels: An analytical study of copper-alloy artefacts from Early Bronze Age Thasos, north Aegean

Abstract

Thasos is an island in the north Aegean with a long tradition in mining and metallurgical production the emergence of which could be traced to the end of the Neolithic and the beginning of the Early Bronze Age (c. 3200 BCE). The current study is focused on copper alloy artefacts that were found in several Early Bronze Age settlements on the island to provide an understanding of how they were produced and utilised/consumed by their users. Application of laboratory instrumental techniques, namely compositional analysis by X-ray Fluorescence and metallography coupled by Scanning Electron Microscopy (SEM/EDS) are used to illuminate our understanding of the methods utilised for their fabrication and the choice of certain alloys that were common during the Early Bronze Age. Results have revealed the predominance of arsenical copper fabricated by casting, followed by stages of hammering and annealing. A single example of a leaded copper object shows no parallels among the studied assemblage or other contemporary finds. The average arsenic contents of 2.9 wt% might be the result of accidental alloying of copper with arsenic-bearing copper minerals or indeed a conscious selection of mixed ores that contained both metals. Geological information is taken into consideration attempting to locate the possible sources of copper and arsenic-bearing minerals on the island that were potentially utilised as raw materials. Results point to the possible utilisation of fahlores (tennantite in particular) from a mining location close to Limenaria that could yield arsenical copper in a single stage smelting process. Considering the co-occurrence of arsenic and low silver contents in the fahlores from this location, they match well to the minute silver contents detected in two artefacts of the assemblage under study. Such preliminary findings are of special importance as they contribute to the ongoing discussion concerning the production of arsenical copper across the Aegean during the EBA.