South Terras Mine was first worked by the South Terras Tin Mining Company Limited from 1872 to 1888, but returns of tin were small and iron ore and ochre were the main products. Uranium was discovered in about 1885 when a lode was cut that produced an unusual apple-green mineral: at first this was thought to be copper ore, but was later identified as
torbernite. The
adit level where the uranium minerals had been discovered had a door placed on it for security. The torbernite was locally nicknamed "Green Jim" after the name of the then managing director of the mine James Harris-James. The company was reformed in 1889 as the Uranium Mines Ltd and Harris-James stepped down as a director. In 1889 the mine was acquired by the Minerals Research Syndicate Limited and the workforce was tripled to about thirty. All uranium ores were sold to Bettmann & Kupfer in
Brunswick, Germany, mainly for
uranium glass manufacture. The "Kingsway Syndicate" purchased ore from South Terras, a contract having been agreed to supply 7.5g of
radium bromide worth over £30,000 for the London Radium Institute. The institute began the treatment of patients in 1906/1907, South Terras having supplied the 7.5g of radium bromide from over 100 tons of
pitchblende ore. Societe Industrielle du Radium Limited was registered in 1912 to acquire South Terras mine, working it to provide ores for its subsidiary company - Societe Francaise du Radium - to process in France. There were eight directors, four English and four French. These included Jacque Danne and Sydney Fawns. The outbreak of
World War I ended the company's activities. Operations were recommenced in 1921; this time the mine was equipped for radium extraction on site, the first and only mine in the United Kingdom to do so. The mine was managed by Marcel Pochon, an ex-student of
Pierre Curie, who moved to Cornwall to live in a bungalow next to the South Shaft. A description of the processing plant appears in 1925. The mine had closed before 1928 when the British & General Radium Corporation Limited acquired it from the previous lessee; the company was a German syndicate managed by a Swiss director, Dr I. Strauss. Marcel Pochon remained on site with his family throughout these changes, presumably as a technical engineer and scientist. The mine was abandoned in the early 1930s and Pochon left for Canada in 1932 to establish the radium refinery for the
Eldorado Mining Company in
Port Hope, Ontario. Pochon operated that refinery from 1933 to 1945 and it became a key component of the
Manhattan Project. South Terras was the subject of diamond drilling investigations by the Atomic Energy Division of the
British Geological Survey in 1953. == Site of special scientific interest ==