Rare Earth Elements

Currently no REE deposits have been discovered in Northern Ireland but a number of grass roots opportunities exist for explorers with experience in this particular sub-sector. One of the classic geological environments for REE deposits to form is in pegmatite veins, near to the edges of large acid intrusions that have cooled slowly within the earth’s crust. This allows for the development of late stage fluids that can concentrate the REEs and certain other minerals (including tantalum and lithium). If the pegmatite size and density is great enough an economic deposit may be formed. There are three main acid intrusive centres in Northern Ireland that could be considered prospective for REE mineralisation.
The Mourne Mountains
In the late 1970s a limited amount of exploration work was completed but this focused on uranium and tin mineralisation. As such the REE potential of the Mourne Mountains complex has never been properly evaluated, but given the common association of Sn and U with REE deposits, the area can be considered geologically prospective. Radiometric and stream sediment surveys were completed and a number of coincident anomalies in the south and eastern Mournes were identified.
Overall, the Mourne Mountains complex proved to have the highest background radiometric values of all the Irish intrusives but it was the tin anomalies that were followed-up. Bedrock cassiterite in quartz veins cross-cutting the granite was identified at the intersection of two fracture sets with values up to 0.4% Sn over 0.3m. No REE values were analysed.
Some of the most extensive Nb, Ta, and Yb anomalies occur in the soils of the Mourne Mountains.
Demand for Rare Earth Elements (REEs) and tantalum continues to grow in line with our demands for smaller electronic technology and increased performance. Recent restrictions on export by China (which produces over 97% of the world’s rare earth supply) mean that there is growing concern that a global shortage may soon be faced. Searches for alternate sources are ongoing and previously uneconomic deposits are now becoming viable.
Slieve Gallion
Three of the REEs were analysed as part of the regional geochemical survey of the western half of Northern Ireland. Very similar patterns were produced for cerium, lanthanum and thorium with strong but possibly formational anomalies located over the extreme west of Co. Tyrone.
Perhaps more interestingly, anomalies also occur over the Slieve Gallion complex and parts of the Tyrone Igneous Complex. Given the prospective geological environment in these two regions follow up work is merited.
The Newry Complex
The late Caledonian Newry intrusive complex is a multi-pulse intrusion similar in age and style to the Leinster Intrusion in the Republic of Ireland. Both intrusions resulted from crustal melting at the roots of the mountain range formed by the Caledonian orogeny and are dated at around 400Ma. Exploration in the Republic of Ireland has identified pegmatites up to 20m thick by 400m long containing 1.6% Li and accessory tin, niobium and tantalum.
In Northern Ireland, radiometric anomalies believed to be related to uranium mineralisation were identified over areas of the Newry complex during the late 1970s work.
Other Areas
The Tellus geochemistry program has identified anomalous concentrations of Nb and Th in soils on Dalradian metasediments of the Claudy and Ballykelly Formations in Co. Londonderry.
Published: 1st May 2011
Last Updated: 25th November 2011