Characterising Bronze Age copper from the Great Orme mine in North Wales to determine and interpret its distribution

• Main Author: Williams, R. A.
• Other Authors: Ponting, Matthew ; Pope, Rachel
• Published: University of Liverpool 2017
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.755529

The Great Orme copper mine on the coast of North Wales is one of the largest surviving Bronze Age mines in Europe. However, linking the mine to metal artefacts has been impeded by influential claims in the literature of the 1990s that the mine could only produce low impurity metal, which is uncommon in Bronze Age Britain. This has marginalised the importance of the mine as a metal source combined with the claim that the mine was only large because it was worked on a small scale for nearly a millennium. In addition, the past use of lead isotopes has produced confusing evidence due to the mine’s radiogenic ores and a lead ore vein crossing the copper deposit. The main objective of this thesis is to resolve the confusion and contradictions in the literature and allow the distribution of Great Orme metal to be determined and interpreted. Applying an interdisciplinary approach, involving ore geology, mineralogy, geochemistry and pyrotechnology, a new methodology has been developed. This is based on the concept of establishing mine-based metal groups rather than using the existing artefact-based metal groups. Ore samples, taken throughout the Bronze Age mine workings along with metal produced from controlled smelting experiments, have been analysed using a variety of analytical techniques. The full range of the probable chemical composition field and the lead isotope field of Great Orme metal has been established. Confidence in this mine-based metal group has been increased by its consistency with the bronze tool fragments excavated in the mine and with copper prills from the nearby Pentrwyn Bronze Age smelting site. The results have shown that, contrary to the low impurity claims in the literature, the Great Orme mine mainly produced copper with significant nickel-arsenic impurities. Applying the mine-based metal group model to existing data on all Bronze Age metalwork assemblages suggests there was a zenith with large-scale production in the Acton Park assemblage phase (1600/1500-1400 BC), followed by many centuries of very low production. Distribution maps of artefacts that have been newly correlated with Great Orme metal have revealed possible distribution networks across Britain and into mainland Europe. In particular, there are strong links into Brittany but also stretching as far as the Baltic area, possibly related to the amber trade. The implications for mine organisation are reviewed including a potential link to the invention of the palstave, an iconic symbol of the Middle Bronze Age, and possible support or control from the agriculturally richer area of north-east Wales with its strategic position into wider communication networks.