Tin Sources for Prehistoric Bronze Production in Ireland

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Ireland is important in the early metallurgy of northwest Europe, for it has given us a large majority of the Early Bronze Age artefacts from the whole British Isles. Is there tin-ore to have been mined in early Ireland to produce this bronze or must it have come from elsewhere?

Ireland and early metallurgy

For many years Ireland has been central to interpretations of the earliest metallurgy in the British Isles, and ongoing excavations at Ross Island in Killarney look set to confirm an early origin for extractive copper metallurgy in the country (O'Brien pers. comm.). Well over 2000 Early Bronze Age copper-based artefacts have been attributed to Ireland (Harbison 1969a; 1969b) compared with a few hundred from England, Scotland and Wales (Burgess 1974; Coles 1968-9; Savory 1980). Proposals that this distribution indicated an Irish origin of British metallurgy received considerable support from compositional analysis of British and Irish metalwork (Case 1954; 1966; Coghlan & Case 1957) and hand specimens of Irish copper ores (Coghlan 1963; Butler 1963). Case (1966) concluded that the earliest metal artefacts in circulation in the British Isles were predominantly produced in Ireland by an 'industry' based in that country. These artefacts, characterized by a high arsenic, antimony and silver impurity pattern, were, it was suggested, made from sulfide ores of the fahlerz type (Coghlan 1963). At the time it was proposed that such ores were being mined in antiquity from Mount Gabriel in southwestern Ireland (Jackson 1968; 1979). Detailed re-examination of the ores, however, has shown that arsenic- and antimony-bearing minerals are totally absent from Mount Gabriel (Ixer 1990; O'Brien 1990; O'Brien et al. 1990), although they have been found elsewhere in southwestern Ireland (Ni 1991). Recent schemes have divided the Early Bronze Age of the British Isles into numerous technological stages (Burgess 1974; 1979) which have been associated with characteristic impurity patterns (Northover 1980a; 1980b; 1982), but Case's (1966) thesis, that all of the earliest material was produced in Ireland, has remained unchallenged.

Much of the Early Bronze Age metalwork from the British Isles, in common with that from elsewhere in Europe, has a high arsenic content. The supposed advantages of arsenical copper and the possibility of its deliberate production in the European Chalcolithic have been discussed by Wertime (1964), Charles (1967; 1979; 1980; 1982), Eaton & McKerrell (1976), Rapp (1988), Northover (1989) and Budd (1991). Some researchers saw early British arsenical coppers as intentional products from the smelting of arsenic-bearing sulfide (McKerrell & Tylecote 1972; Craddock 1979), or oxide (Tylecote 1976; Charles 1985), zone minerals. More recent work has shown that British and Irish 'arsenical copper' is unlikely to have been deliberately produced; it may have resulted from the primitive smelting of arsenic-bearing cupriferous ores (Thomas 1990; Pollard et al. 1990; 1991; Budd et al. 1992).

If arsenical coppers were not deliberately produced, it is the earliest tin-bronzes which must be considered as the first true alloys with specific physical or mechanical properties achieved by mixing different metals or their ores. Until now, it has been proposed that the practice of alloying copper and tin to produce bronze, like metallurgy itself, developed first in Ireland and later spread to mainland Britain. Ireland is still held to be the sole source of copper for the earliest tin-bronzes both in Ireland and mainland Britain (Northover 1980b). If, as Northover (1982) proposes, alloying with tin was carried out near the copper production centres, it follows that local tin resources must have been available in Ireland in the earliest part of the Bronze Age.

Both Jackson (1979; 1991) and Northover (1988) have concluded that accessible tin resources may have occurred in the Gold Mines River of Co. …