Prospecting for lead ore was being carried on near Keady, and galena occurred is many places in Monaghan . At Conlig, near Newtownards, are old lead mines. Felspar was found in sufficient quantity, and of sufficient purity near Belleek to admit of its being used in the preparation of pottery there. Afterwards, white and black mica impurities increased so much that it was rejected in favour of pure felspar imported from Norway.
Diatomaceous earth is a siliceous vegetable deposit. It is found at various places-Toome, Portglenone, and Kilcrea,-along the banks of the lower Bann. The material is dug, and when dried like peat is white in colour. It is then powdered by machinery and used as an insulator.
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