Tungsten West Hemerdon visit

In October I was lucky enough to visit the Hemerdon / Drakelands Mine near Plymouth in Devon. This trip was organised by the Royal Geological Society of Cornwall and hosted by the mine’s operators - Tungsten West.

This is my first visit to Hemerdon in 10 years, so I was excited to see how the site has changed in this time.

Hemerdon is a tungsten/tin deposit situated in a large granite dyke, hosted by upper Devonian slates on the southwest margin of the Dartmoor Granite pluton. The granite dyke is around 290 million years old.

The mineral deposit is a sheeted vein complex - a series of closely spaced veins largely composed of quartz with some tourmaline, along with wolframite (tungsten ore) and cassiterite (tin ore). This is similar to those deposits at Cligga Head and St Michael’s Mount.

This type of deposit is associated with a style of hydrothermal alteration known as Greisen. This is caused by hot watery fluids passing up through fractures in the rock. It results in mineral assemblages of quartz + mica ± topaz which formed due to the reaction between cooling granite and the hot fluids that are rich in F, B and Li.

The granite dyke formed along a transtensional pull-apart, where extensional faults open up between two NW-SE strike slip faults. The orientation of the veins is also probably controlled by a similar regional stress field, although the closely spaced nature of sheeted vein systems suggests that fracturing could be influenced by fluid overpressure (hydraulic fracturing).

There has been historical tin mining in the area since the 18^th Century. Mining tungsten began in the 20th Century, driven by the use of tungsten to harden steel, particularly around the two world wars. Before this, the presence of tungsten was actually problematic when mining tin, given its similar density making it more challenging to process out the tin.

The site was prospected in the second half of the 20^th Century by British Tungsten Ltd and AMAX, but was unsuccessful. In 2007 the site was bought by Wolf Minerals who developed the mine and built a processing plant, going in to production in 2015. Unfortunately, operational and financial issues forced the company into administration in 2018.

The following year operations were taken on by Tungsten West. Whilst fluctuating tungsten prices have hindered progress, the company is now working towards updating the site with the ambition of going in to production in the second half of 2026.

Tungsten is an important resource in our modern society. Designated as a critical metal by the UK Government, it is an essential component of things like x-ray beams, communication infrastructure, the automotive industry, semi-conductors and the aerospace sector. It also has military applications, for strengthening steel and producing armour-piercing projectiles.

Unfortunately, it is the latter use that has driven the price of tungsten so high at the moment, as many countries embark on rearmament programmes. But there are still lots of important uses of tungsten that are essential in our everyday lives.

According to deposit models, Hemerdon is the 2nd largest tungsten deposit in the world. If the mine goes in to production it would make the UK the third largest producer.

The tour was fantastic. It was great to see the open pit and get up close to some rocks! Open cast mining is preferred over underground mining for this type of deposit - the narrowness, spacing, and frequency of the veins means it’s easier to dig the whole lot out rather than mine individual veins.

After lunch we had a tour around their mineral processing facility. This is one of my favourite things to see - how the mined rock is processed to recover and concentrate the wolframite. Holistically, it’s quite a simple process - crush it down and use gravity to separate out the heavy ore minerals. However, the complexities of the geology along with the scale of the process makes it very complicated indeed! It was great to see how they are problem solving those issues previously experienced on site.

Along with Cornish Metals’ South Crofty project, Tungsten West and Hemerdon offer a real opportunity to bring active metal mining back to the Southwest. Not only will this bring an economic boost, but it will have a really positive impact on local society.

Mining is such an important part of our culture and heritage, and a return to metal mining will make this last 27 years a blip in the 4,500-year history of mining, rather than an end. I’m really excited for it, and wish Tungsten West all the best for the future.

A massive thank you to all at Tungsten West for hosting us, especially Marica Lyndon, Matt Tonkins, Damian Andrews, and the other staff who showed us around. Thank you also to the RGSC for organising the event.