Industrial Minerals

Whilst not being as well known as gold or diamonds, industrial minerals form the backbone of modern society. As any economy continues to grow, the need for these minerals will increase. Many industrial minerals have a variety of different uses making them an attractive mining proposition as they tend to be less sensitive to cyclical market trends.

Industrial Minerals in Northern Ireland

Northern Ireland has a remarkable variety of industrial minerals, many being present in workable amounts capable of contributing to the economy. Five different commodities are discussed here, but please contact the GSNI to learn more about different minerals.

Salt

Bedded halite in the Triassic Mercia Mudstone Group underlies the area between Carrickfergus and Larne and has been worked for over 100 years. Until 1958, rock salt was produced from a number of underground operations and brining was often employed. In 1965 a new mine commenced production at Kilroot, operated by the Irish Salt Mining and Exploration Company Ltd. Access is via a decline and mining is by the room-and-pillar method. Each year up to 500,000t of salt is produced and processed on-site before being sold to the winter road maintenance markets in the UK, Ireland and the USA. Within the mine area, the salt beds vary in thickness from 9 to 27m and occur at five separate levels. However, 15km to the north a drillhole intersected 400m of Triassic halite in three seam groups as well as 113m of halite in the older, deeper Permian Upper Marls.

Bauxite

Bauxite was formed by lateritisation of the basalts of the Antrim Lava Group, producing the Interbasaltic Bed between the two main lava formations. The Antrim bauxite is a residual clay deposit and is very variable in composition, with samples up to 62% Al2O3 and low silica. On a world scale the Antrim bauxites are not economic, but the ceramic and other properties remain to be fully investigated. Where the Interbasaltic Bed outcrops in basalt quarries, it may be economic to work the bauxite on a small scale as at Clinty Quarry in Co. Antrim. The bauxite is processed to produce aluminium ferric sulphate which is used in water treatment plants and sewage works.

Perlite

Perlite is the industrial name for volcanic glass. Explosive volcanic activity at the beginning of the Palaeogene led to the formation of a volcanic diatreme near Sandy Braes, Co. Antrim. The deposit occurs within the Tardree Rhyolite Complex which formed within the vent. Following minor trial work in the 1940s the deposit remained untouched until the mid-1980s when planning permission was granted to develop an extractive facility. Perlite has a variety of uses and forms an inert, lightweight and porous granular product used in construction materials, filtration systems and agriculture.

Gypsum

Gypsum for use in the building plaster industry has been mined from the Permian rocks of Co. Cavan since 1937. Similar rocks occur in Northern Ireland and gypsum was found in the Upper Marls below east Belfast. Significant quantities of gypsum and anhydrite have also been intersected in mineral exploration boreholes drilled through the Lower Carboniferous of Co. Fermanagh.

Diatomite

Diatomite occurs as a 0.9m thick deposit north of Lough Neagh and was worked until the late 1960s. It forms a chemically inert powder that can be used as a filler in paint, plastic and rubber manufacture and also in the food and pharmaceutical industries.