Talk by Tom Cotterell on The manganese mines of Rhiw, Pen Llyn, Gwynedd, Wales'--Reporter Christine Critchley

摘要

Thirteen people attended the talk, many of whom were going to the area the next day on the branch field trip to Rhiw, Benallt and Nant. Tom not only gave a well illustrated talk but also brought several specimens and a poster showing the rediscovery of minerals in the Rhiw area. Tom introduced the geology of the area and described the early development of manganese mining in the area. In the early 19th century the black oxides being used for chlorine production for bleach and for decolourising glass. In the mid 19th century the manganese extracted was added to iron to produce hard steels. By the mid 20th century huge deposits of manganese were found in the Harlech Dome, but there they stayed as foreign imports were cheaper and of higher grade.