Mineralization at Parys Mountain

Staff: T.F. Cotterell [with Dr D.A. Jenkins]

Parys Mountain was the largest copper mine in the world during the latter half of the 18th century. The mineralogy and geology are complex, with extensive faulting and folding of ore bodies containing intergrowths of fine-grained sulphides dominated by pyrite and chalcopyrite.

Ever since the closure of the mine there have been problems with acid mine drainage (AMD), caused by the oxidation and decay of pyrite left in place underground and within the extensive opencast workings. This oxidation brings with it a whole range of post-mining mineral growths, which form stalactites and efflorescence on tunnel walls and in exposures within the opencast workings at surface.

Dr. D.A. Jenkins, a member of the Parys Underground Group, has carried out extensive fieldwork at the site. Recent collaboration has allowed more detailed analysis of specimens to be made, thus improving our knowledge of the complex mineralogy. The aim of this project is to produce an authoritative account of the mineralogy at Parys Mountain and in particular an understanding of the post-mining mineralogy brought about by the oxidation of the remaining sulphide minerals both underground and at surface.