Diatomite is a highly coveted mineral made up of diatom fossils – a single-celled micro-algae – and used by the food industry to filter wines, beers or orange juice, but also pharmaceuticals (antibiotics, plasma) or cosmetics (perfumes, toothpaste).

The multinational Imerys, a specialist in minerals for industry, intends to file an authorization to extract in 2023 on the narse (“wet zone” in Occitan) of Nouvialle, a former crater lake which extends over 400 hectares between Saint -Flour and the Cantal mountains. And for its opponents – local elected officials, farmers, hunters, hikers – it is the very future of the precious site that is at stake.

The Natura 2000 classified area is home to many protected species. Diatoms were deposited there more than five million years ago, forming “the largest deposit in Europe”, according to Imerys.

With its microscopic pores, diatomite “is a natural sieve without equal in the animal and plant world. Nothing can replace it”, assures François Gueidan, director of an Imerys factory which already operates a quarry in Cantal.

The site, which employs 32 people, is nearing the end of its operations: “in five to six years, another quarry will have to be opened. We have no plan B,” he said. Seventy-five indirect jobs depend on the operation, according to him.

In front of the factory, a semi-trailer loads diatomite in bulk. A few kilometers away, the quarry stands out in the middle of the mountain vegetation, with its gaping hole and its whitish dust raised by the wind.

In December 2021, the diatomite deposits were recognized as “of national interest” by the regional quarry scheme, approved by the prefect of the Auvergne Rhône-Alpes region.

What reinforce the projects of Imerys and its main competitor Chemviron, also established in the region.

Imerys promises to limit extraction to 10 hectares, or 20,000 tonnes of diatomite per year, sold between 250 and 450 euros per tonne.

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On site, at the entrance to a meadow on the ground still muddy in this scorching month of June, the May orchis hides its purplish flowers behind the tall grass: this protected species of wetlands “is threatened by quarry projects like many other plants here”, deplores Christophe Grèze, spokesperson for the collective for the narse of Nouvialle which brings together associations such as the LPO, the Federation of hunters or the Federation of hiking.

“It is a site for which the European Union is undertaking preservation actions, so it is in complete contradiction with the opening of a quarry”, says Christophe Grèze.

Crossed by two streams, flooded part of the year, the narse also plays “a buffer role” by retaining a large amount of water, according to him.

The collective fears the impact on water resources while the government launched in March a new national plan for the protection of wetlands, ramparts against global warming.

“Ten hectares of quarry is a small area but in reality, it is 80 to 100 hectares that will be artificialized with the projects of the two multinationals”, explains Anthony Marque, another member of the collective, to a group of high school students. came from Niort.

The collective also highlights the thirty farmers, to whom humidity offers a fodder resource “more and more essential in a context of climate change”.

The elected officials of the three municipalities concerned, Valuejols, Roffiac and Tanavelle are also opposed to the project. They are supported by the president of Saint-Flour community, Céline Charriaud.

“It’s a quality milk and cheese production area. We have a whole policy of attractiveness of the territory where we value the living environment. It’s incompatible with an open-pit mining operation of this scale”, explains the elected official who had a resolution voted to request a biotope protection order.

Asked by AFP, the prefect of Cantal Serge Castel did not wish to speak, while Imerys has not yet filed a request.

The narse “already benefits from sufficient protection to preserve its balance without requiring the adoption” of this decree, the prefecture said in a written response.

The site is also crossed by the GR4, linking Royan (Charente-Maritime) to Grasse (Alpes-Maritimes) over 1,526 km.

“Hikers come to see remarkable fauna and flora”, underlines Alex Seher, member of the Cantal branch of the Hiking Federation, faced with the “unimaginable” project.

For its part, Imerys promises to rehabilitate the site after exploitation and is happy to show the group’s “showcase”, a former quarry filled in and then vegetated.

A marsh has been reconstituted there: “We do not claim to recreate what nature has built, but something that has an ecological function”, argues François Gueidan, defending a “reasonable and reasoned extraction”.

If diatomite is no longer exploited in France, the second largest producer after the United States, “then it will be imported from Mexico or China in cargo ships, with a considerable carbon impact”, he warns.

However, according to Anthony Marque, “alternatives to diatomite exist”: they are “not necessarily profitable yet. But by 2030, we have time to make them perfectible”.

At the same time, the collective is thinking about sustainable activities to compensate for the jobs threatened by the closure of the factory, which worries some elected officials. At the beginning of June, he also filed an appeal before the administrative court of Lyon against the new career plan.

“It’s a bit like David against Goliath”, admits Anthony Marque, but “the battle has only just begun”.

There remains a fundamental question that goes beyond local issues, according to Céline Charriaud: “Where is the general interest?”

“Either we consider that the subjects of water, energy transition, ecological, maintenance of biodiversity, qualitative agriculture are subjects of general interest which transcend all the rest. Or we consider that mining activity is superior to that”.