High Quality Content by WIKIPEDIA articles! Hemerdon Mine, alternatively known as the Hemerdon Ball or Hemerdon Bal Mine, is a historic tungsten and tin mine. It is located 11 km (7 miles) NE of Plymouth, near Plympton, in Devon, England. It lies to the north of the villages of Sparkwell and Hemerdon and adjacent to the large china clay pits near Lee Moor. The mine, which has been out of operation since 1944, except for the brief operation of a trial mine in the 1980s, hosts one of the largest tungsten and tin deposits in the world.