Baryte, Barium sulphate, BaSO4. Gorn mine, Nr Llanidloes, Central Wales Orefield. These specimens were collected from a sorting platform at the old mine workings. They are massive with some cavities containing platy crystals in the cockscomb formation. The larger specimen shows some witherite on the lower right hand side.
Cafartha mine, Staylittle, Central Wales Orefield. This pretty little specimen is a mix of host rock, with precipitated quartz, some of which is druzy and lining small cavities. There are also very minor amounts of galena on the surface. Brecciation is the result of inwardly exploding walls of deep fractures when there is a sudden decrease of pressure causing shards of wall rock to be injected into the hot mineral rich fluids which are circulating through the fracture.
Galena, PbS, and Quartz, SiO2. Aberdaunant mine, Nr. Llanidloes, Central Wales Orefield. Collected from spoil heaps at the mine, these specimens are a galena- quartz breccia The quartz is massive with no sign of crystals. The galena is also massive with just a small indication of a few small broken crystals, which display the natural cleavage planes. As is often the case in this area, some of the exposed broken surfaces have a bright blue sheen.
Quartz, SiO2. Bryn y Rafr mine, West Wales. Two specimens of poorly defined quartz crystals, which appear to have grown into a cavity from the rock wall. The specimen in the centre could be described as "skeletal" quartz because minerals which were once embedded in the quartz have weathered out leaving numerous small cavities. There are also a few sugary deposits of quartz, with no well defined crystals. This type of specimen is very common on the mine spoil heaps.
Chalcopyrite, CeFeS2. Siglenlas mine, Nr. Llanidloes, Central Wales Orefield. These specimens of brecciated material are typical from this site. Some of the exposed chalcopyrite not yet weathered, displays the usual pale brassy colour. The specimens are made up of quartz, host rock, and chalcopyrite. I estimate the chalcopyrite content to be between five and ten percent, which would have made the processing economically viable.