Bronze Age Copper Ores of the British Isles: Rethinking the Role of Trace Element Analysis of Artifacts by Karen M. Spence (original) (raw)
Related papers
Oxford Journal of Archaeology, 1998
Numerous analytical studies during the latter half of this century have contributed to the compilation of a large compositional database of Early to Middle Bronze Age copper-based artefacts revealing distinctive impurity patterns which appear to change over time. However, attempts to relate these data to copper ore sources proved problematic in the absence of firm evidence for the location of prehistoric copper mines. Over the last fifteen years this situation has changed dramatically with the discovery of numerous Early and Middle Bronze Age copper mines in England and Wales. This study is the first attempt at a comprehensive mineralogical survey of the principal mines investigated to date in order to define the likely composition of the copper ores as mined in antiquity for comparison with the artefact database. The study suggests that the majority of these mines can only have produced essentially pure copper. Only one mine, Ross Island, is likely to have produced copper with a significant level of impurities. The relative purity of the known ore sources is contrasted with significant levels of various metallic impurities among the analysed artefacts, leading to the conclusion that metal circulation and mixing may have been more extensive than previously thought even during the earliest part of the Bronze Age.
Mineralogy of British Bronze Age copper ores
Numerous analytical studies during the latter half of this century have contributed to the compilation of a large compositional database of Early to Middle Bronze Age copper-based artefacts revealing distinctive impurity patterns which appear to change over time. However, attempts to relate these data to copper ore sources proved problematic in the absence of firm evidence for the location of prehistoric copper mines. Over the last fifteen years this situation has changed dramatically with the discovery of numerous Early and Middle Bronze Age copper mines in England and Wales. This study is the first attempt at a comprehensive mineralogical survey of the principal mines investigated to date in order to define the likely composition of the copper ores as mined in antiquity for comparison with the artefact database. The study suggests that the majority of these mines can only have produced essentially pure copper. Only one mine, Ross Island, is likely to have produced copper with a significant level of impurities. The relative purity of the known ore sources is contrasted with significant levels of various metallic impurities among the analysed artefacts, leading to the conclusion that metal circulation and mixing may have been more extensive than previously thought even during the earliest part of the Bronze Age.
Trace Element Fingerprinting of Ancient Copper: A Guide to technology or Provenance?
The hypothesis that trace element concentrations should be a guide to the provenance of ancient metals has been around for more than a hundred years. Although very large analytical programs for ancient metal objects have been based on this concept, its validity is still in dispute with opinions that rangefrom complete rejection to virtual acceptance. However, the apparent dichotomy expressed in the title is a false one. There m a number of elements whose concentrations m predominantly govemd by ore mineralogy/composition and couM thus, in principle, be used for provenance detenninations. Other elements, found in ancient copper metal artefacts, m more closely related to the smelting process und so are of little use in provenance studies.
Roman copper metallurgy: analysis of artefacts from northern Britain
1997
A survey of the range of Roman copper (Cu) alloys is offered. This is based primarily on the analysis of almost 1200 Roman artefacts from sites throughout northern Britain. This large body of data is examined from a number of different perspectives (e.g. typological, cultural, chronological). A full list of the data as an ''interactive database'' is to be published separately in Internet Archaeology.
Journal of Archaeological Science, 2022
Since the mid-1970s a Bronze Age assemblage of metal objects has been recovered from the seabed off the south Devon coast at Salcombe, southwest England. The assemblage spans two suspected shipwreck events and comprises nearly 400 pieces of raw materials and finished artefacts, primarily in copper, tin, bronze and gold. Among these are 280 copper and 40 tin ingots, by far the largest discovery of Bronze Age ingots in either metal from northwestern Europe. Research in recent years revealed the microstructural and chemical nature of the ingots and enabled some preliminary conclusions on the metals trade in Europe in the Later Bronze Age. The present study aims to extend this knowledge by determining the tin, copper and lead isotopic compositions of the ingots using HR-MC-ICP-MS. In addition, bronze artefacts (swords, rapiers, palstaves and weights) from the Salcombe site are included in the multi-proxy approach in order to investigate their history and the possible relationships between finished products and ingots. In combination with the available chemical data of previous studies, the current results of the tin metal show that most likely two tin sources in southwest Britain supplied the ore for their production. This also sheds light on Late Bronze Age tin ingots from Israel that share the same geochemical characteristics with one group of the finds from Salcombe. Although the tin in the bronzes is similar to the tin in the ingots, it is not certain that the latter were used to make the bronzes. Correlations of copper and tin isotopes and trace elements of the bronzes point to a mixing or even recycling of copper-tin alloys rather than the alloying of individual components of copper and tin. However, the copper ingots from the assemblage could have been an additional component in the mixing process given their impurity pattern and isotopic composition. At the same time, a close relationship between swords of the Rosnoën type and palstaves from the cargo is disclosed. Lead isotope ratios for their part suggest Sardinian and/or south Spanish copper ores as a source for both the copper ingots and the copper of the bronzes. This would mean long-distance metal trade in the Later Bronze Age in both cases and would provide new insights into the interpretation of the prehistoric networks in Europe.
Pollard, A. M., Bray, P., Gosden, C., Wilson, A., and Hamerow, H. (2015). 'Characterising copper-based metals in Britain in the first millennium AD: a preliminary quantification of metal flow and recycling', Antiquity 89.345: 697–713., 2015
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.
Archaeometry
We present a new methodology for interpreting lead isotope data from archaeological copper alloy objects. It is not based on the conventional isotope ratio biplots, which were originally devised to allow the calculation of the geological age of the lead mineralization, but is derived from isotope mixing models, more often used for presenting strontium isotope data. We illustrate the method by reworking published data on Sardinian Nuragic oxhide ingots and copper alloy artefacts. While we confirm the consensus assumption that the oxhide ingot fragments found on Sardinia are isotopically consistent with Cypriot copper ores (although we see no isotopic reason to favour only Apliki, as originally suggested), we also show that there is evidence for mixing between local and ingot copper in some objects, which was previously not detected. More broadly, we suspect that the apparent mismatch between some source allocations for copper drawn from isotope geochemistry and the rest of the archaeological data in some cases might be due to mixed isotopic signals being incorrectly assigned to a specific source, and suggest that the method presented here will reduce the chances of this happening.