South Terras Mine in Cornwall was mined for a number of metals, including radium for Marie Curie's research. Now it is abandoned and noted for having dangerous radon concentrations. South Terras Mine is between the villages of St. Stephen and Grampound Road. The active life of South Terras spanned six decades, roughly divided equally between iron, uranium, and radium production from 1870 to 1930. Uranium is widely distributed throughout Cornwall, but this is the only mine where uranium was the main metal.
The mine was originally worked for iron. The iron deposit at South Terras is regarded as a metamorphic one in greenstone rather than a true lode. The ore near the surface is in the form of ochre, being underlain by magnetite.
1873 The uranium lode was discovered. The primary ore of uranium worked at South Terras was uraninite or pitchblende, a variable oxide of uranium. The bulk of the ore, mainly pitchblende, was worked out when the mine closed in 1903.
1874 new pit workings had been taken down to their economic limit, and a transition to underground mining enabled the ore body to be further worked. Power to the site was provided by flat rods from a water wheel which also drove a set of stamps in the valley, a short way upstream on the feat serving Tolgarrick Mill.
1889 Uranium Mines Limited acquired the mining rights, granted for twenty-one years.Over 40 tons of uranium ore had already been sold from South Terras, from the lode which was from four to five feet wide carrying a mineralised leader averaging two to six inches in width. The uranium lode was over 250 fathoms in length with near unbroken uranium mineralisation. Some parts of the lode assayed 30 percent uranium.
1890 Captain W.R. Thomas reported that 33 persons were employed on the mine. By March the shaft was 5 fathoms below adit. The main shaft reached 35 fathoms depth, and crosscutting and development along the 10 fathom level continued.
1891 Uranium Mines Ltd was voluntarily wound up with a view to reconstruction as the mine had a large quantity of ore but lacked the chemical plant to treat it. Work continued at the mine on a reduced scale with no more than eleven employees until 1899.
1899 Minerals Research Syndicate Limited acquired The Uranium Mines. Royalty payable to the Boconnoc Estate was based on one twenty-fourth of the sales value.
1903 to 4th February 1905 the property was in the hands of a receiver and operations were practically suspended.
1904 the discovery of radium.
1905 British Metalliferous Mines Limited became operators of South Terras in on a 21 year lease from 1900. Production of ore in 1905 was derived from waste tips only, underground mining being resumed in 1906. Assays of uranium ranged from 3 to 31 percent.
1906. A contract for the supply of 7 1/2 grammes of pure radium bromide valued at £30,000 for use in the new Radium Institute was agreed
1911 the mining setts including South Terras were sold for £3,100 to an undisclosed buyer.
1912 Societe Industrielle du Radium gets a new lease for 21 years to March 1934 and a subsidiary company, Societe Francaise du Radium, set up to treat the ore from South Terras in France, where at the rate of 5 tons per day, 5 milligrams of radium bromide valued at £16 per milligram were to be extracted.
1914 The outbreak of war in caused operations at South Terras to be suspended.
1922 A new extraction plant completed in 1922. Initially this was to treat some 200 tons of ore containing an estimated 2500 milligrams of radium.
1922 pumping and mining operations had recommenced and the extraction plant was performing satisfactorily.
1924 that amalgamation of South Terras Mine with Tolgarrick Mine with the aim of increasing their activities in radium products.
1925 the Boconnoc Estate initiated action which was to lead to the downfall of the Societe Industrielle du Radium. The landlord was suspicious that he was not receiving his just rent.
1928 British & General Radium Corporation Limited take a concession from the previous lessee. This was in fact a German Syndicate and was headed by Dr. I. Strauss a Swiss director. The mine was now pumped to the 40 fathom level below adit.
1929 The company approached the landlord with a view to negotiating a new lease to 1950
1930 the mine closed and for the next seven years protracted negotiations continued to seek common ground in creating a new lease.
1937 The landlord successfully obtained a Court order for the repossession of the mine.
A full report on South Terras Mine
Mining in St Austell Area