Cornish Lithium are utilising modern exploration techniques to re-evaluate the mineral potential of the southwest; respecting the traditions of the past whilst looking to the future. Exploration is focussed on delineating permeable crosscourse structures at depths of up to 1km, with the aim of drilling boreholes in to them and extracting the lithium-enriched geothermal brines which flow within the structures. Cornish Lithium envisage that the lithium will then be directly extracted from the brines utilising new extraction techniques (see section on Li extraction).
Exploration on the project to date is at an early stage. Cornish Lithium’s technical team are building a digital 3D model of the regional geology, with information from both historical sources such as estate maps and mine closure plans, and from more modern sources such as satellites and regional geophysical surveys. Current work is focussing on defining priority areas for ground-based geophysics, results from which will guide the location of subsequent exploration boreholes.
As Cornwall’s mining industry spans hundreds of years, there are centuries worth of maps and plans containing important geological information which is being captured and digitised by Cornish Lithium. Many of these have been made available to Cornish Lithium from private collections through the various minerals rights agreements which the Company have in place. Cornish Lithium’s archivist, Neil Williams, ensures that all documents are handled appropriately and digitised in the optimal manner. Once digital copies have been made, they are imported in to GIS software, georeferenced, and both geological and mineral rights information is extracted in to the Company’s 3D digital model.
Georeferenced historical maps by Thomas (1819) and Symons (1845)
Structural information captured from historic mapping. The same areas have been mapped by numerous people at different points in time; correlation of these features between maps increases confidence in them
A whole host of data sources are being utilised to best define prospective areas for extraction of lithium enriched brines within Cornish Lithium’s mineral rights holdings. The Tellus South West survey in 2013 comprised a high resolution airborne magnetics, radiometrics and LiDAR surveys alongside the G-BASE regional soil and stream sediment geochemical sampling surveys. The data generated from this project is very useful for mineral exploration, and is being integrated into Cornish Lithium’s database of historical geological information to produce priority areas for further investigation.
Cornish Lithium is planning to run a geophysics programme, and is currently assessing which techniques would be most suitable.
Cornish Lithium has been involved in an Innovate UK funded project run in conjunction with the Satellite Applications Catapult, looking at how satellite data can be used to support lithium exploration and to provide an environmental baseline for mining activities within Cornwall. Earth observation data has been used to remotely map geological structures, clay alteration, land surface temperature and vegetation anomalies across two areas of interest in Cornwall at United Downs and St Austell. Along with its fellow mining consortium partners, including the British Geological Survey, Camborne School of Mines and North Coast Consulting, Cornish Lithium then used local knowledge and field evidence to test the validity of the remote mapping by satellite, as will be discussed. The earth observation outputs were then integrated and combined to produce a prospectivity map for lithium exploration in Cornwall.
In parallel, earth observation data has been used to better establish the environmental baseline for the two project areas of interest. Vegetation mapping using satelllites has produced a much higher resolution map of vegetation cover and land usage than the existing standard CEH Land Cover map. The mapping techniques developed by the earth observation companies can also be used to provide ongoing, remote monitoring of the environment as projects progress: invaluable data for land users who need to continually prove their minimal impact on their local area.
To find out more about the project click here.