Manganese Mining In Doddiscombsleigh by Andrew
In the SouthWest of England the main producer of manganese ore was initially the mine at Upton Pyne which commenced production in 1770, although the deposits there were gradually worked out and the mine closed in 1823, and from about 1812 onwards the main production was coming from mines in Tavistock and the Teign Valley in Devon, which presumably involves the mines being investigated