Metals Make the World Go Round

As early as the 15th century BC, the existence of complex trading systems was attested in the Mediterranean region. The common exchange commodities were metals such as copper and bronze used for the manufacture of tools and weapons. Determining the origin of these metals is the key to reconstructing ancient trade.

The CEZA project “Metals Make the World Go Round”, funded by the Volkswagen Foundation and undertaken in cooperation with the Hebrew University (Jerusalem, Israel), relies on the combination of state-of-the-art multi-isotope analyses and traditional historical-archaeological approaches to investigate the copper trade in the Mediterranean region during the Bronze and Iron Ages.

By the Late Bronze Age (LBA) (15th-early 12th centuries BCE) – the first large-scale international trade system already existed in the Mediterranean, shaping the interactions between the cultures and geo-political entities. A lion’s share of this exchange of materials and objects was based on metals, particularly bronze (copper and tin), used to produce tools and weapons, the control of which was of crucial importance for the ruling elites.

Reconstruction of trade networks is highly dependent on the ability to identify raw-material origins. Until the advent of Lead Isotope Analysis (LIA) in the 1980s, object shape was the sole indicator for provenance. A comparison of the Pb isotopic signature in an object with the composition in the parent ores allowed determining the source region. This became the key to reconstructing ancient trade networks and economic, cultural, and technological interactions.

While LIA is efficient in identifying Cypriot ores, it is insufficient for distinguishing between ore sources of the same geologic ages, for example, the copper ore sources of Sardinia (Iglesiente) and the Southern Levant (Arabah). Such differentiation is imperative for understanding the contribution of each region to the global network and its implications for the local production in each. The present project relies on the application of a multi-proxy analytical approach while considering the archaeological context of copper use and trade.

For the first time, the methodology of Osmium Isotope Analysis (OIA) will be used to provenance ancient copper. Until now, this method was limited to iron provenance studies, as iron is enriched in osmium. However, OIA is also expected to be effective in determining the source of copper artefacts, since iron oxides were commonly used as additives to improve the efficiency of copper extraction. Combined with the comprehensive archaeological study, this methodology will open new research avenues for more effective investigations of ancient Mediterranean exchange networks.