Peter Bray

A new interpretative approach to the chemistry of copper-alloy objects: source, recycling and technology

The metal composition of bronze alloys has been routinely examined as a means of inferring the source of the ore. But bronze is recycled, and the quantity of some components, such as arsenic, is depleted every time the alloy is melted down. Since the Early Bronze Age of the British Isles was largely supplied from a single mine on Ross Island, Co. Kerry, tracking arsenic content shows the number of re-melts and this gives the object a biography and a social context. Applying this ingenious new procedure to their large database, the authors also winkle out other sources of supply and new insights about the technology involved.

Characterising copper-based metals in Britain in the first millennium AD: a preliminary quantification of metal flow and recycling

Abstract For many years, archaeologists and archaeometallurgists have suggested that recycled copper might have constituted a significant component of the metal in circulation in Britain during the first millennium AD. They have generally failed, however, to suggest a way of observing and quantifying this phenomenon. Here the authors propose a new methodology to rectify this. A large new database of chemical analyses of British copper alloys dating from the late Iron Age to the early medieval period demonstrates the potential of their approach; it shows that significant and measureable changes occur in metal circulation at the beginning of the first century AD and in the early Saxon period.

Is there something missing in scientific provenance studies of prehistoric artefacts

Determination of the provenance of material culture by means of chemical analysis has a long and distinguished history in archaeology. The chemical analysis of archaeological objects started in the intellectual ferment of late-eighteenth-century Europe (Caley 1948, 1949, 1967; Pollard 2013), almost as soon as systematic (gravimetric) means of chemical analysis had been devised (Pollard in prep.). Many of the leading scientists of the day, such as Vauquelin, Klaproth, Davy, Faraday and Berzelius, carried out analyses of archaeological objects as part of their interests in the contents of the ‘cabinets of curiosities’ of the day (Pollard&Heron 2008). The subject moved frommere curiosity to systematic and problemorientated study with the work of G¨obel (1842),Wocel (1854), Damour (1865) and Helm (1886), who essentially formulated the idea of ‘provenance studies’—that some chemical characteristic of the geological rawmaterial(s) provides a ‘fingerprint’ which can bemeasured in the finished object, and that if an object from a remote source is identified at a particular place, then it is evidence of some sort of direct or indirect contact and ‘trade’ between the two places.

Physical Barriers, Cultural Connections: Prehistoric Metallurgy across the Alpine Region

This paper considers the early copper and copper-alloy metallurgy of the entire Alpine region. It introduces a new approach to the interpretation of chemical composition data sets, which has been applied to a comprehensive regional database for the first time. The Alpine Chalcolithic and Early Bronze Age each have distinctive patterns of metal use, which can be interpreted through changes in mining, social choice, and major landscape features such as watersheds and river systems. Interestingly, the Alpine range does not act as a north-south barrier, as major differences in composition tend to appear on an east-west axis. Central among these is the prevalence of tin-bronze in the western Alps compared to the east. This ‘tin-line’ is discussed in terms of metal flow through the region and evidence for a deeply rooted geographical division that runs through much of Alpine prehistory.

Tracing the flows of copper and copper alloys in the Early Iron Age societies of the eastern Eurasian steppe

Abstract Early Iron Age pastoralists of the Eurasian steppes relied heavily on copper for weapons and ornaments, and new analysis of metal composition enables long-distance networks to be identified. Primary circulation from source areas where copper was mined can be distinguished alongside the secondary circulation of alloy types with high proportions of tin-bronze or leaded tin-bronze. The relative presence of trace elements, depleted during recycling events, provides a proxy for the flow of metal between regions. The localised seasonal movements characteristic of these mobile steppe societies underlie some of these patterns, but the evidence also indicates more extensive transfers, including the direct movement of finished objects over considerable distances.

Chemical and Isotopic Studies of Ancient Metals

Chemical treatment of metal artifacts to determine their composition was one of the first applications of science to archaeology. In this chapter, various chemical and isotopic analytical techniques are described as they relate to the study of ancient metals. In addition, the problems and pitfalls of such analyses, especially as they relate to attempts to assign “provenance” to ancient artifacts, are discussed. In general, the chemical and isotopic analysis of metal artifacts as well as metallurgical artifacts (e.g., crucibles and slags) is essential for reconstructing the ancient technological process.

Bronze Age metal circulation in China

Abstract The Shang (c. 1500–1045 BC) and Zhou dynasties (c. 1045–771 BC) of China are famous for their sophisticated ritual bronze vessels. Sourcing the leaded tin-bronze has, however, proved to be a challenge. A new systematic approach to metal chemistry uses trace elements and isotopes to characterise the underlying circulation pattern. It reveals the complexity of the copper sources on which the late Shang capital at Anyang depended for its bronzes, suggesting the transport of copper from distant regions in the south, on the Yangtze, and from north-east China. The new interpretational system furthers our understanding of the network on which successive Chinese dynasties depended for copper, lead and tin, and attempts to give equal weight to the archaeological and chemical data.