Mwyngloddfa Llechweddhelyg
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Description
Description Located in the western sector of the Central Wales Orefield, Mwyngloddfa Llechweddhelyg is situated on the ENE-trending Camdwr Lode, approximately 1.5 km south of Bontgoch and 4 km east-north-east of Penrhyncoch. The spoil tip associated with the eastern shaft is of special scientific interest for the quantity and quality of a diverse range of secondary minerals. Primary lead-copper mineralization has been deeply oxidized by supergene alteration, probably during sub-tropical weathering in Tertiary times, to an assemblage characterized by goethite, malachite, chrysocolla, cerussite, pyromorphite and wulfenite. Accessory minerals, a few of which may have formed within the dumps, constitute an extensive suite that includes mattheddleite, susannite, schmiederite, caledonite, elyite and the first Welsh occurrence of chenite.