Reconstruction of an Iron Age setlement - western Ireland




With the ressurgence of interest in Celtic jewellery and sculpture, and their creation from various different metals, it is interesting to see where in Ireland some of the metals may have been mined and smelted, and in what approximate quantities, during the Bronze Age. Two metals make up the alloy bronze. These are tin and copper. Copper is more plentiful than tin. Ireland during the Bronze Age was a centre for some very elaborate bronze metalwork. It is estimated that in the early Bronze Age in Ireland, not more than 14% of artifacts were of bronze. The remainder were made from copper only, and being a softer metal than bronze would have been less durable. During this period it has been estimated that in Ireland a total of 1.72 tonnes of smelted bronze was used. This would require, at an average of 10.5% tin concentration, 0.18 tonnes of tin.

Estimates of the scale of copper mining during the Bronze Age indicate that ore equivalent to some 1400 tonnes of copper metal was mined. That seems to me a very large amount of copper. The ore has to be smelted before producing copper, and this leaves a lot of the ore as a waste product. Also the efficiency of converting ore to smelted metal can be as low as fifty per cent. But even this would mean that 700 tonnes of finished copper metal would have been produced, which is a very considerable quantity. This figure is far in excess of what it is believed that Ireland produced in copper and bronze artefacts, thus it is reasonable to presume that Ireland in the Bronze Age not only produced fine examples of metalwork, but was also a major exporter of copper.

There are ten mines in Ireland that would have produced copper. These are: Ross Island, Killarney, Co Kerry; Coad Mountain, near Caherdaniel, Co Kerry; a mine near Eyies, Co Cork; Ballyrisode (Ballyrizard), Co Cork; Mt Gabriel, near Schull, Co Cork, Horse Island, Roaringwater Bay, Co Cork; Derrycarhoon, north of Ballydehob, Co Cork; Danes Island, Bunmahon, Co Waterford; Avoca mines, Co Wicklow; and Rear Cross/Kilcommon area, Co Tipperery. These all seem situated on the coastal peninsulas of south west Ireland, apart from Ross Island which is slighty inland.

Of course many other exciting developements were taking place in these areas and throughout Ireland during the Bronze Age, including the construction of many stone circles such as this magnificently sited one at Drombeg, Co Cork.

A great deal of work has been done on the Mt Gabriel mine near Schull, Co Cork. This has enabled a picture to be built up of how a mine operates. An estimated 48,000 imperial gallons of water were siphoned over a forty eight hour period from this mine. That is a very large mass of water! From the amount of water siphoned from a mine can be gauged the amount of rock, mineral and gangue. This has been calculated as 571 long tons. This represents about 48% of the total void of the mine. The total tonnage of copper extracted from the Mt Gabriel mine is therefore estimated as 1198 tonnes of rock. This amount of rock would have contained almost 24 tonnes of copper. As these figures are estimated from only one of the twenty six mines that were in use on Mt Gabriel during the Bronze Age, the total amount mined would have been in the region of 623 tonnes. This natural ore would then have to be smelted, a process which could have reduced the total by almost half, leaving approximately 312 tonnes of pure copper. The figures in this article are rather elaborate, but fascinating nonetheless as they show how much metal must have been available in prehistoric days. 312 tonnes of copper from the Mt Gabriel area alone is a lot of copper, and that's just from a very small part of Ireland. As for tin, the second ingredient of bronze, there are seven mines where tin could be mined in those days: Lough Leane, Killarney, Co Kerry; Allihies mine, near Castletown, Co Cork; Gold Mines River, near Woodenbridge, Co Wicklow; Cronebane mine, Avoca, Co Wicklow; near Greystones, Co Wicklow; Malpas mine, Kilkenny Hill, Co Dublin; Slieve-na-miskan, Mourne Mountains, Co Down. All these mines, apart from the one near Greystones, Co Wicklow, can produce cassiterite. The mine near Greystones, Co Wicklow produces the rare mineral stannite, from which tin is also obtained.

(Cassiterite is the ore from which tin is extracted. The word comes from the ancient Greek 'Kassiteros', meaning tin. In Classical times Britain was renowned for its prolific exporting of tin, not only to Europe but to more distant coutries such as Greece. The word Kassiteros gave rise to the ancient Classical name for Britain which was The Cassiterides).

The most likely candidate for obtaining tin in Ireland during the Bronze Age is Gold Mines River, near Woodenbridge, Co Wicklow. It has long been though that this river was a source of gold during this era. More recently, gold has been obtained here for many centuries by panning. Cassiteite is also found in this river. The theory goes that if gold was mined from this location, cassiterite would also have been found and probably used. In 1849, experiments were conducted by W. Mallet, who found twenty seven different varieties of minerals in the Cold Mines River. He describes the cassiterite he found as follows; " In grains varying in size from fine sand up to pebbles of half an inch (1.77cm) in diameter, and for the most part of a dark brown colour with some fragments of various tints of yello and red; some presenting the peculiar appearance to that which the name 'wood tin' has been given." The 'wood tin' refers to the rare mineral stannite, a tin-bearing ore mentioned earlier.

A guide to the volume of tin that can be obtained from the Gold Mine River is in the figures of cassiterite that have been estimated during the period 1795-1963. During this period it has been estimated that roughly 120 kg of cassiterite, with a potential yield of 95 kg of tin were obtained. This figure would produce about half the required tin that was used during the early Bronze Age in Ireland. But we have to take these figures with caution, as the amount of cassiterite mined was very sporadic and erratic. An exact and accurate figure cannot be obtained.

It really has to be said that though tin was available in Ireland during the Bronze Age, there would not have been very much. It is unlikely that there would have been enough to provide for early Bronze Age Ireland. By the time of the late Bronze Age, when the mastery of smiths was at its peak and many beautiful artefacts were created, with the resulting increase in bronze metal that would be required it would be very doubtful if there was enough tin in native sources to supply the needs of the smiths. But from the above details some Irish tin was certainly available for use in the production of bronze.

- © M.K Pearce

The Bronze Age is generally accepted as spanning circa 2200-1000BC.