Carrières souterraines de la Malogne

Useful Information

Location: At the southern end of Cuesmes. Rue de la Malogne. (50.4257°N 3.9219°E)
Open: Only after appointment, for groups of 20+ persons.
Fee: Groups (20+): Adults EUR 4.
Classification: SubterraneaRock Mine phosphate in limestone
Light: bring torch.
Dimension: L=175,000m
Guided tours:
Photography: allowed
Accessibility: no
Address: ASBL Malogne, Faculte Polytechnique de Mons, Rue de Houdain, 9, 7000 Mons.
Thierry Mortier (scientific coordinator), Tel: +32-475-345478. E-mail:
David Stradiot (scientific animator), Tel: +32-471-742167. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


1877 beginn of mining.
1925 mines closed.
1934 mines reopened.
1958 mines finally closed.
1995 first public tours.


The Carrières souterraines de la Malogne (underground Quarries of Malogne) are a series of phosphate quarries in limestone, constructed in the room and pillar method. The vast labyrinth is mostly private and not accessible, some parts are under protection because of the bats and also not accessible. However, there is a small part which is used by the Service de Géologie Fondamentale et Appliquée de la Faculté Polytechnique in Mons for educational purposes. They offer various courses for school pupils and also provide guided tours into the quarries, but only for groups of at least 20 persons and as far as we know only in French. The site is part of the Géoparc du Bassin de Mons and in 2015 they tried to get on the UNESCO World Heritage List, but the WHL requires the accessibility for tourists and so they didn't even make it on the tentative list.

The quarries cover an area of 68 hectares southwest of Cuesmes. Only 40 hectares are accessible, but a part is below the ground water, which means there is water on the floor and it must be visited by boat. The rest of 28 hectares is completely flooded and not accessible, or it was backfilled with gangue. The mined material was processed in a factory, which was located at the Esplanade de la Malogne. The surrounding forest named Bois de la Malogne has grown on the factory's schlamm basins from the 1930s and 1940s. There were several parts operated by different owners and so there were several other factories, but they were smaller.

There was no older mining of the chalk phosphate, because it became useful as a resource after the invention of the chemical phosphorus extraction process for the manufacture of fertilizers. This was in the mid 19th century. The chalk could not be used for any other purpose, it is unsuitable for making lime and too brittle for building material. But the chalk is quite interesting as it contains various fossils, mostly belemnites and mosasaurus teeth, but also oysters and even some turtles. The chalk was formed during the Cretaceous, it belongs to the Masstrichtian.

The content of phosphate in the chalk was discovered by Prof. Charles Hardy de Beaulieu in 1858. The Rolland quarry at Cuesmes was one of the first to be exploited for phosphate in 1877. The mines have only one level, which follows the phosphate rich chalk, and as they reached the groundwater a level pumping system with dykes was install to allow further quarrying. A failure of such a dyke in 1911 caused a flood, but fortunately there was no fatality.

Between 1932 and 1935, and in 1962 the unused parts of the mine were used for growing mushrooms. At that time long parallel rows of horse manure seeded with mycelium and then covered with earth or peat were used. It seems this was not very successful, as it was abandoned pretty fast.