The Mineralogy of Bronze Age Copper Ores from the British Isles: Implications for the Composition of Early Metalwork

Abstract

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.

Isotopic Composition of Lead in Copper Ores and a Copper Artefact from the La Profunda Mine (León, Spain)

“…At this point, it is worth commenting that although radiogenic copper deposits have been described in other parts of the world, they are very rare (Budd et al 2000). One of the best examples of a Bronze Age mine with copper mineralization containing uranogenic lead is the Great Orme mine, near Llandudno in North Wales (Ixer and Budd 1998). This spot was defined by Budd et al (2000) as the only mining site in the British Isles that presented this unusual mineralization.…”

“…). One of the best examples of a Bronze Age mine with copper mineralization containing uranogenic lead is the Great Orme mine, near Llandudno in North Wales (Ixer and Budd ). This spot was defined by Budd et al .…”

Boom and bust in Bronze Age Britain: major copper production from the Great Orme mine and European trade, c. 1600–1400 BC

“…Metalwork from the predominant period of mine workings (the Middle Bronze Age) typically contains arsenic and nickel impurities, whose importance lies in providing a chemical ‘fingerprint’ for identifying potential mine ore sources. Influential articles, however, have claimed that the Great Orme ores produced only uncommon, low-impurity metal, and so could not be the main source of metal from the Middle Bronze Age (Craddock 1994; Ixer & Davies 1996; Ixer & Budd 1998; Northover 1999; O'Brien 2015). This claim of only low-impurity ores was based on the absence of nickel and arsenic minerals, although the levels of these elements were not checked using chemical analyses.…”

Localized ductile thrusting north of the Variscan Front, Ross Island, southwest Ireland

“…In the 19th century there was still sufficient copper ore remaining to produce 3220 tons of ore at a grade of 17.5% copper between 1804 and 1810, (Weaver 1838) and a further 1529 tons at 13.6% copper between 1827 and 1829 (Cole 1922). A wide range of primary copper-iron-lead-zinc sulphides and sulpharsenides, together with minor cobalt, silver and molybdenum mineralization, is present as fine-grained, banded, massive polymetallic sulphides and later vein-style chalcopyrite-tennantite ores (Ixer and Pattrick 1995, in press;Ixer and Budd 1998). Because the mineralization is restricted to two small areas on the south of the island, at Blue Hole and Western Mine, and also on Crow Island (Figure 2), which lie close to the Ross Island Thrust, most previous workers have assumed that the epigenetic mineralization was associated with thrusting, perhaps envisaging fluid flow along the thrust plane (e.g.…”

“…Our study is part of an interdisciplinary project investigating the geology, mineralization and geoarchaeology of the Ross Island copper mines. Ross Island, and especially the Bronze Age workings within sulphide and sulpharsenide ores at Western Mine and Blue Hole, is of great importance in our understanding of the origins of metallurgy in the British Isles (O'Brien 1995;Ixer and Budd 1998).…”