A mineralogical tour of Ireland (Part 4): Ulster

Stephen Moreton (UK) Our journey around Ireland concludes in Ulster. This comprises Northern Ireland, which is part of the UK, and the counties of Cavan, Donegal and Monaghan, which are part of the Republic of Ireland. As geology is no respecter of politics, the national border is ignored here. I assure my gentle readers that this is not intended as a political statement! The geology consists of metamorphic rocks and granite intrusions in the west, a huge expanse of Tertiary basalt in the eastern half, and a series of Tertiary granite intrusions in the southeast corner. Carboniferous limestone makes an appearance in some places, but is not as well endowed with minerals as further south. Fig. 1. The four regions of the island of Ireland. Fig. 2. Ulster in more detail. Donegal, occupying the northwest corner of the island, has such a varied geology that it has long been a favourite venue for university field trips. In spite of this variety, there are few mining sites. Lead has been mined at Glenaboghil, Keeldrum and Glentogher, but these old mines are not noted for specimens. However, minor yellow powdery greenockite occurs at the first location and green coatings of pyromorphite at the second. What it lacks in mines, the county makes up for in silicate minerals. The beryl occurrence at Sheshkinnarone is probably the best known. Finger size green and blue-green prisms in a white quartz matrix occur at several spots here. The richest is just outside the garden wall of … Read More

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