This article was written by the Great Wheal Vor Community and Environment group and was revised in September 2024
The Wheal Vor mining district lies in an area of Devonian Slate between two granite masses at Tregonning/Godolphin hills and Carnmanellis. This mining area, historically known as Great Wheal Vor (GWV) is a compact area of approx 10.5 km by 6.5 km and is thought to have been mined for tin for the past 1000 years.
Fig1. Basic geology of the Great Wheal Vor district.
The intention of the exploratory drilling being carried out in the area by Cornish Tin Ltd (CTL) appears to be to demonstrate to investors the viability of a new underground tin mine beneath the middle of the parish of Breage in the west of Cornwall. CTL have completed 3 rounds of exploratory bore holes, which began in 2022 under General Permitted Development Orders approved by Cornwall Council.
While recognising that only a small percentage of exploratory drilling programs develop into extractive mines, the GWVCEG strongly oppose further development of this site by CTL.
History of the Wheal Vor Site
There were two periods of intensive tin mining in this small historic mining area between 1810 -1848 and 1860 -1874 which were world leading ventures at the time, with over 50 sites extending down from 3 meters to 540 meters. Thus the
area is honeycombed with abandoned shafts, galleries and adits, some mapped, some unmapped.
Fig 2. Map of the recorded workings of Great Wheal Vor – 1847 (based on MRO R137)
Fig 3. Plan of the shafts, workings and lodes at Wheal Metal. – 1870s (based on MRO R137 and 175 and the 1878 O.S. map)
Fig 4.Cross section of the eastern workings of Great Wheal Vor (based on MRO R137) The above maps show the complexity of known shafts, lodes and adits in the period between 1840 and 1875
The UK’S unique manorial system dating from the 11th century separates the ownership of minerals underground from that of the ownership of the land at the surface.
Traditionally in Cornwall the owners of the various manors became de facto owners of the underground minerals.
Fig 5 below
In 1921 the properties and land within the Manor of Treworlis were put up for sale by the Trelawney estate. These sales contained the caveat that all minerals and rights of access were still in the ownership of the Manor. 
Since the closure of mines from 1860 onwards, the area has developed into a quiet residential community with minimal commercial presence. It is unlikely that any of the current owners of property and land would have expected any new mining activity to develop.
Many sites in the area have been sterilised by the presence of toxic mine tailings and it has only been in the last 25 years that there has been a gradual re-wilding of the landscape.
Many subsidence events have occurred during the last 75 years despite a number of mines being capped in the interests of health and safety. Mine leaching into the streams which drain the area both to the north and to the south, continues to pollute the waters, with tests showing unacceptable levels of nickel, cadmium and mercury.
Flooding, particularly from mines in slate bordering onto granite, has caused many problems during the history of Great Wheal Vor. The period of disuse would make Cornish Tin’s project expensive and ecologically dangerous to develop. At the nearby South Crofty tin mine project, the reputed cost of water removal and filtration is estimated to be in excess of $18 million.
The Great Wheal Vor Community and Environment Group believe that for the reasons detailed above, any new tin mining activity is unnecessary, impractical and environmentally unacceptable to our community.
Unnecessary
The IRENA World Energy Transition Outlook Report 2022 is clear that the list of critical metalliferous metals highlighted including the group Rare Earth Elements (REE)’s does not include tin.
The British Geological Society’s report of 2021 included projections which did (by dubious calculations) consider the metal as a critical one. However, in the same report, it estimates that recycled tin had made a 31% contribution to total production. It noted that recycled production in the UK ranked nil – with no figures available.
South Crofty Mine, which is now in the later stages of development and has the benefit of existing mine infrastructure, has claimed that by 2026 they will be able to provide enough tin to satisfy UK demand.
The market growth indices in the British Geological Society’s Report take no account of the substitutional effect (for example, through nano technology in solders), changes to vehicle Total Industry Volumes (TIV), alternative power sources or cultural changes in transportation.
The stalling of the UK’s new battery ventures should spur both industry and environmentalists into placing greater emphasis on high level recycling.
Impractical.
We believe the project poses a high risk of failure due to cost escalation.
1. It is new in the UK to undertake underground mining beneath an established community setting where the historic mining landscape is known to be unstable.
2. Exceptional cost of filtration due to water levels and high pollution. 3. CTL have pledged that if the project moves beyond the exploratory stage, it will be ‘green’ in all aspects.This inevitably impacts the cost/availability of plant and the use of ‘green’ stabilising slurry if they are to avoid the charge of ‘greenwashing’.
4. Increasing demands from planners and community for realistic long term financial bonds from miners to indemnify against insolvency, for site landscaping and toxic leaching, etc.
5. New developments in technologies impacting on tin pricing. 6 Imminent launch of Government ‘pension dashboard’ giving more intelligence to pension savers pursuing ethical investments
Environment.
Should CTL’s activities move beyond the exploratory stage, affected communities and planners would first demand proof that adequate measures had been taken to prevent air pollution, noise pollution, light pollution, structural disturbance, vibration, flooding and, most importantly, water pollution. They would also require protection of flora and fauna.
The community will closely monitor CTL communications to the public as thus far communication been almost non-existent.
For example, CTL has said to the media from the very start of the project, that there have not been any meaningful objections to its plan. We disagree.