Marcasite / Quartz, Bryn y Rafr. (CWO)

Marcasite / Quartz, Bryn y Rafr. (CWO)

Marcasite,FeS2, and Quartz,SiO2. Bryn y Rafr mine, west Wales. Country rock with quartz and marcasite content. The marcasite has suffered from "pyrite decay", breaking down into sulphuric acid and hydrous iron sulphate, the light coloured deposit on the surface.