In Ireland the metal first used was copper. Native copper is plentiful in Ireland, and has been chiefly obtained from the Counties of Wicklow, Waterford, Cork, Kerry, Tipperary, and Galway. In Waterford stone implements have been found in copper mines in ancient workings, showing copper was mined for at an early period.[7] The time during which copper was in use was probably relatively only a short one, much shorter than the Neolithic Period or than the true Bronze Age. The evidence for this period is the large number of flat copper celts which have been found in the north and south, and east and west, of the country. The earliest copper celts resemble in form the stone celts from which they are derived, and were cast in open moulds on one side only, and then hammered flat on the other. Moulds for casting celts in this way have been found in Ireland. It is also extremely interesting to notice that some stone celts betray the influence of metal types by their form. It may be well here to meet an objection that has been raised against a special use of copper in Ireland. It has been urged that the large number of flat copper celts may have been due to a scarcity of tin, and that as copper cannot be cast in closed moulds, casters who could cast advanced forms of bronze celts were obliged to return to the primitive form necessary for casting in an open mould. Copper ores are, however, very rarely found in a pure state, and the small impurities of antimony, arsenic, &c., combine in the smelting with the copper, and lend a hardness and ductibility which would enable it to be cast in closed moulds.[8] The analyses of Irish copper celts agree among themselves, and substantially with those from other countries, the small quantities of tin, antimony, arsenic, &c., which are found being due to impurities in the ore. The celts may be taken to be of copper, and not of poor bronze.[9] The earliest copper celts resemble the stone celts from which they are derived; some of them are small. A development takes place throughout the series, the celts becoming larger and the edges thinner as they approach the bronze forms. No trace of a stop-ridge is ever found on copper celts. [7] Sir R. Kane, Industrial Resources of Ireland. Second edition, 1845, p. 189. [8] See analysis of a socketed celt of an alloy of copper and antimony found at Elbing, West Prussia, Journal Anthropological Institute, vol. xxxvi, p. 21. [9] See paper "Irish Copper Celts," Journal Anthropological Institute, vol. xxxi, p. 265, where the question is fully dealt with. [Illustration: Fig. 1.--Copper Halberd, Birr find.] The principal finds are as follows:-- 1. Three copper celts, three copper awls, and a copper knife found, in 1874, in a bog at Knocknague, Kilbannon, County Galway. Purchased from the finder, Michael Rafferty, by the Royal Irish Academy. (Fig. 3.)