Hemerdon Mine, also known as Drakelands Mine, is a significant tungsten and tin deposit located near Plymouth in Devon, England. It is situated within the Dartmoor National Park area and represents one of the largest undeveloped tungsten deposits in the world outside of China.
History and Development
The Hemerdon site has a history of mining activity dating back to the early 20th century, primarily for tin. However, its substantial tungsten reserves were identified later.
- Early 20th Century: Limited extraction of tin and tungsten occurred during periods of high commodity prices.
- Late 20th Century: Extensive exploration and feasibility studies were conducted, confirming the economic potential of the large, low-grade tungsten-tin deposit. Various companies held interests in the project over the decades.
- 2010s: The project gained significant momentum under the ownership of Wolf Minerals Limited, an Australian-listed company. Construction of an open-pit mine and processing plant began in 2014.
- 2015-2018: The mine commenced commercial production in late 2015, primarily producing tungsten concentrate (wolframite) and a tin by-product. It was briefly Europe's only active primary tungsten mine.
- 2018: Wolf Minerals entered administration in October 2018, citing ongoing operational challenges, lower-than-expected recoveries, and a significant drop in tungsten prices. Production ceased, and the mine was placed on care and maintenance.
Geology and Mineralogy
The Hemerdon deposit is a greisen-bordered vein and stockwork system hosted within the Hemerdon granite, a satellite intrusion of the much larger Dartmoor Granite batholith.
- Ore Minerals: The primary ore minerals are wolframite ((Fe,Mn)WO4) for tungsten and cassiterite (SnO2) for tin.
- Gangue Minerals: Associated minerals include quartz, muscovite, topaz, fluorite, and tourmaline.
- Formation: The mineralization is epithermal and related to late-stage hydrothermal fluids associated with the intrusion and cooling of the granite.
Significance
Hemerdon Mine holds strategic importance due to tungsten being a critical raw material. Tungsten is vital for industries such as aerospace, defence, automotive, and electronics, particularly in the production of cutting tools, alloys, and filaments. The mine represented an opportunity to reduce Europe's reliance on external sources, especially from China, which dominates global tungsten production.
Environmental Considerations
Being located near Dartmoor National Park, the mine's development involved significant environmental impact assessments and mitigation strategies. These included managing water discharge, dust, noise, and visual impact, as well as plans for eventual site restoration.
Future
As of late 2018, the mine remains inactive. Its future depends on a combination of factors, including global tungsten prices, new investment, and the resolution of the challenges that led to Wolf Minerals' administration. The substantial reserves, however, indicate its potential for future re-opening should economic conditions and operational strategies align.