The deposit Hemerdon sits on is geologically unique in south-western England: a sub-vertical Early Permian granite dyke, more than 100 metres wide, intruded between Devonian slates known locally as killas. Mineralising fluids penetrated the fractures and laid down sheeted veins of greisen-bordered quartz, ferberite, and cassiterite. The mineralisation begins at the surface and extends to at least 400 metres down. Hemerdon's resource is over 300,000 tonnes of tungsten metal: the fourth-largest tungsten deposit in the world. The locality is also renowned for high-quality scorodite specimens, considered among the best in Europe. Pharmacosiderite, cassiterite, ferberite, and wolframite of museum-grade quality have all been recovered, secondary arsenate minerals forming in the weathered upper oxidation zones of the ore body.

Hemerdon Wolfram Ltd built a 90,000-tonne-per-year mill in 1939 that began operating in 1941, achieving 55% wolfram recovery. The Ministry of Supply concluded in 1942 that Hemerdon offered Britain's best prospect for large-scale domestic tungsten production. The government took the mine over from its private operator and hastily threw up a much larger plant in 1943, theoretically capable of treating over a million tonnes per year. Labour shortages and mechanical faults dragged actual output far below that figure: about 200,000 tonnes of ore moved through the new plant, yielding 180 tonnes of concentrate. Operations ceased in June 1944, when access to overseas tungsten was restored. Rumours of a Korean War-era restart came to nothing, and following the Westwood Report in 1956 the government sold off the plant in 1959. The concrete roads built around the wartime mills became, until about 1972, the venue for speed hill climbs by the Plymouth Motor and Kart Clubs.

From the mid-1960s onward, a succession of companies kept rediscovering Hemerdon. British Tungsten Ltd, owned by Canadian entrepreneur W. A. Richardson, increased the proven resource to 5.6 million tonnes by 1970. Hemerdon Mining and Smelting Ltd partnered with mining giant AMAX in 1977 and ran a $10 million exploration programme that pushed the resource to 49.6 million tonnes by 1980. Permission to mine was sought in 1981, refused after a public enquiry in 1984, and finally granted in 1986. Then the project sat on the shelf for two decades. North American Tungsten plc inherited it in 1997 and discarded it in 2003, the upkeep costs of C$150,000 per year eating almost a third of the company's annual budget. By 2005, sustained tungsten price rises made everything look possible again.

Wolf Minerals, an Australian-listed specialty metals company, acquired the leases in 2007 on a 40-year deal, renamed the project Drakelands Mine 'to recognise the local community,' and started construction in 2014. First ore went into the plant in June 2015. If production had hit projections, Drakelands would have been the largest tungsten concentrate producer in the world. It never did. The plant struggled with ore that turned out to be ferberite rather than wolframite, requiring different extraction chemistry, and Wolf Minerals ceased trading on 10 October 2018, losses estimated around 100 million pounds. Tungsten West plc took over in 2021, floated on the London AIM market, and rebuilt the processing flowsheet from the basics, planning to sell construction aggregate as a by-product to improve the economics. Interim operations restarted in 2023. As of early 2024 the mine still awaited full regulatory permission. The fourth-largest tungsten deposit on Earth has spent more time waiting than working.