The Hemerdon tungsten-tin deposit was discovered in 1867. In 1916, due to war associated tungsten shortages, an exploration and development program was initiated, which outlined a tin-tungsten stockwork suitable for opencast extraction. In 1917, Hemerdon Mines Ltd decided to construct a 140,000 tonne per year mill, and shortly afterwards opencast ore mining operations began. The mine was operated in 1918-1919, during which time it processed 16,000 tonnes of ore. When the British government stopped accepting tungsten ores under the war pricing scheme the mine was forced to suspend mining operations.
Several attempts were made to establish a higher and stable price for tungsten from the government, including an application supported by Winston Churchill for recognition of wolfram mining as a key industry. However after further price decreases, milling operations were suspended and the mill components were sold off. In 1934 increased tungsten prices resulted in renewed prospecting of the deposit, along with metallurgical testwork. In 1939 further shortages of tungsten due to WW2 led to Hemerdon Wolfram Ltd constructing a 90,000 tonne per year mill with 55% wolfram recovery, which began operation in 1941.
The Ministry of Supply carried out extensive evaluation of tungsten deposits in the UK, and it was concluded by 1942 that Hemerdon offered the most potential for producing tungsten on a large scale. The government took over the mine from Hemerdon Wolfram Ltd. A resource of 2.5 million tonnes of 0.14% tungsten trioxide in addition to tin was outlined, and a new plant was hastily constructed.
The new plant took over operation from the old plant in 1943, and theoretically should have been able to treat over 1 million tonnes per year; however labour shortages and mechanical faults resulted in a much lower production. Ore output from a mixture of underground and opencast mining methods was documented as over 200,000 tonnes, with a resulting 180 tonnes of tin/tungsten concentrate during the period of government operation. Operations ceased in June 1944 due to access to overseas supplies being restored.
The plant was kept in place after the war, and the government was rumoured to have planned restarting production during the tungsten shortages associated with the Korean War. However, nothing came of this and following the Westwood Report in 1956, the government decided to seek a private partner to move the mine’s development forwards. After further decreases in the tungsten price, resulting in the closure of the Castle-an-Dinas Mine tungsten mine in Cornwall, the government sold off all the plant in 1959.
An abandoned open-cast tungsten mine near Plymouth in Devon - this locality is famed for its high quality scorodite (among the best in Europe) and cassiterite.
Aerial View (Click for Details)
On 4th December 2007 it was announced that Australian company, Wolf Minerals LLC had acquired the rights to mine this deposit, and current plans are to reopen the site as a full-scale opencast metal mine for tungsten and tin, producing up to 3000 tonnes of tungsten metal per year.
The original name for the workings was "Hemerdon Bal", this was corrupted over time (possibly due to a mis-spelling on Ordnance Survey maps that remains to this day) to "Hemerdon Ball". The current owners refer to the deposit just as the "Hemerdon Mine".
Sources: Wiki And Mindat