Campagne d'acquisition par géophysique héliportée.
© Alexandre Magnan
In line with the political impetus following the conclusions of the "Varin Report” on securing supplies of mineral raw materials, submitted to the French government in 2022, the French President announced in September 2023, at a meeting of the Ecological Planning Council, that the Inventory of France's Subsurface Mineral Resources (IRM - Inventaire des Ressources Minérales) would be updated. This new inventory is also part of the exploration programmes provided for in the European directive on critical metals (the Critical Raw Material Act, which has been in force since May 2024).
The aim of this programme is to improve our knowledge of the country's subsurface in order to identify areas likely to contain mineral resources of interest, which could then be studied by more in-depth exploration by mining companies under exclusive research permits (PER - Permis Exclusif de Recherche). In furthering our knowledge of the resources available in France, this inventory will help to secure the supply of mineral resources and French sovereignty, thereby strengthening the resilience of our economy while supporting its re-industrialisation. It complements studies being carried out elsewhere to develop so-called secondary mining, i.e. methods of recycling the metals present in end-of-life objects and industrial waste.
Breakdown of the 5 geographical zones targeted by the mineral resources inventory.
© BRGM
Probable deposits in France
Five areas have been identified and will be covered by data acquisition campaigns: the western Massif Central, the Morvan-Brévenne area, the Vosges, Occitanie-Cévennes-Cerdagne and the French Guiana northern furrow. The results, once interpreted, will identify the most favourable areas for the presence of deep deposits.
The project, launched in 2025 for an initial period of 5 years, will cost a total of €53 million and will be funded as part of France 2030 by the French National Research Agency, ANR. To achieve this, BRGM will be relying heavily on its dedicated subsidiary, BRGM Explore, as well as specialist subcontractors and scientific partnerships.
Updating the mineral resources inventory requires a great deal of expertise. Work is already underway to analyse historical samples and harmonise databases from various sources (BRGM geological data, old prospecting campaigns, etc.). In addition, major airborne geophysical surveys will be undertaken using the most modern methods to gather indirect data on the nature of geological structures in the subsurface and the fluids that flow through them, from the near surface to more than a thousand metres below it. These heliborne and airborne survey programmes will benefit from the experience gained in recent years in the Massif Central and the Vosges.
Concomitantly, sediment samples will be taken from the watercourses for panoramic geochemical analyses in order to supplement existing geological knowledge and cross-reference the data with geophysical studies.
All of this information will then have to be cross-interpreted to identify areas that are likely to contain ore bodies of interest. To achieve this, a call for innovation will be launched to mobilise companies capable of providing digital solutions to optimise data interpretation, in particular using artificial intelligence.
Mineral resources inventory, fifty years on
In the 1970s, France had already undertaken an inventory of its mineral resources, which was conducted by BRGM and regularly updated until the early 1990s. However, the previous inventory focused on certain substances (22 in total) that corresponded to the priorities of the time. Many other elements that are now considered critical and strategic (lithium, tantalum, caesium, gallium, germanium, hafnium, etc.) were not investigated, and the analytical capabilities of the time did not allow for very precise detection of the concentration-levels in the rock. In addition, there were no airborne geophysical surveying techniques available, which meant that deep exploration of the country's subsurface was not possible at the time. This new inventory paves the way for wider and deeper coverage of the areas studied and for more precise detection of substances. In particular, this should make it possible to identify deposits "hidden beneath surface cover", which have never been explored in the past, or extensions at depth of deposits that are already known.
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