Mineral Extraction

Castlecomer Plateau

The Castlecomer ‘plateau’ is a 30 km long (NS), 22 km wide (EW), basin-shaped, upland, wedged between the valleys of the Nore and Barrow rivers. Located mainly in north Kilkenny and south Laois, the plateau is called after the town and district of Castlecomer near its centre, and rises steeply from the adjacent lowlands and is mostly at a height of 200-300 metres. Composed of sandstones, grits and ‘coal measures’ from the Upper Carboniferous, this area has been worked for coal from the seventeenth century and perhaps earlier. Mines, most of them shallow and small- scale operations, were once quite widespread, but commercial operations are now long ceased. The steep escarpment of the plateau is especially striking when viewed from the Barrow valley. A smaller plateau, the Slievardagh hills, lies to the south-west, beyond the Nore valley. Like Castlecomer, the Slieveardagh plateau was in the past a focus for small-scale mining activity.

Copyright Alan Vaughan.
Castlecomer Plateau
Copyright Alan Vaughan.

Castlecomer Plateau

The Castlecomer ‘plateau’ is a 30 km long (NS), 22 km wide (EW), basin-shaped, upland, wedged between the valleys of the Nore and Barrow rivers. Located mainly in north Kilkenny and south Laois, the plateau is called after the town and district of Castlecomer near its centre, and rises steeply from the adjacent lowlands and is mostly at a height of 200-300 metres. Composed of sandstones, grits and ‘coal measures’ from the Upper Carboniferous, this area has been worked for coal from the seventeenth century and perhaps earlier. Mines, most of them shallow and small- scale operations, were once quite widespread, but commercial operations are now long ceased. The steep escarpment of the plateau is especially striking when viewed from the Barrow valley. A smaller plateau, the Slievardagh hills, lies to the south-west, beyond the Nore valley. Like Castlecomer, the Slieveardagh plateau was in the past a focus for small-scale mining activity.

Copyright Alan Vaughan.
Enlarge image

Ireland’s mineral reserves

Ireland has a diversity of mineral deposits, with a mining history spanning over 4,000 years. See here for a brief overview of Ireland’s mining history.

The island of Ireland has a widely varied geological framework, with rocks ranging in age from Proterozoic (2,500 million years ago) to the present day (see image). The island can be divided into a number of mineral provinces endowed with a broad range of base and precious metals as well as industrial mineral deposits. Large parts of Ireland are covered by metasediments and metavolcanics of Proterozoic (2,500 years ago) and Lower Palaeozoic age (250 million years ago). These rocks are known to contain significant base metal mineralisation (e.g. copper at Avoca) and gold-bearing quartz veins. The latter style of mineralisation has been the focus of extensive exploration efforts in Northern Ireland, and in 1999, an opencast gold mine was opened at Cavanacaw in Co Tyrone. The Lower Carboniferous (360 million years ago) limestones of the Irish Midlands (the Central Ireland Basin) are host to one of the great orefields of the world.


Since the 1960s, Ireland is a leading global producer of zinc, lead and barite. Ireland currently accounts for a significant proportion of both European zinc mine output and European lead mine output. Since this period, fifteen significant zinc-lead deposits have been discovered, with six becoming producing mines. Ireland has been ranked first in the world in terms of zinc discovered per square kilometre, and second in the world with respect to lead. The country is also Europe's largest zinc producer. Its two underground base metal mines account for some 31% of European zinc production, and they also provide 11% of its lead. Ireland's younger rocks contain significant deposits of industrial minerals, most notably the gypsum deposit at [Knocknacran], Co Monaghan, that is found in an outlier of Permian rocks. Zinc, lead and gypsum are key components of the current Irish mining industry (Houses of the Oireachtas, 2015).


There are currently two operating mines in Ireland:

  1. Navan mine in Co. Meath (zinc-lead);
  2. Irish Gypsum’s operations near Knocknacran (open pit and underground) in Co Monaghan (gypsum).

Back to Mineral Extraction