Colombier des Rois Mine, Puy-de-Dôme, France

The Mine du Colombier des Rois or more commonly known as the Mine des Rois, near the town of Dallet in Puy-de-Dôme is undoubtedly one of the richest underground spaces in France. Indeed, it is a hydrocarbon mine operated from the end of the 19th century to 1983.

It is a remarkable site for its exceptional geology, making it possible to retrace the events that took place during the collapse and sedimentation of the Limagne basin. Recently threatened by a destruction strike in the name of the security, this site has been classified and is in the process of being enhanced, and why not one day open to the public ! The identification of bats by the Natura 2000 teams (lesser horseshoe bat especially), the collaboration between geological and naturalist associations (Mur-Allier Nature), geologists and local authorities have made it possible to save these 100 years of mining heritage.

Bitumen filaments in a puddle on the ground.

Long galeries...

Stromatolite with charge figure

History of the Mine

The Rois de Dallet mine, located in the Puy-de-Dôme department, is a particularly interesting mining site for its production of bituminous limestone, a type of sedimentary rock impregnated with natural bitumen. This exploitation, started in 1884 and operated by the Société des Mines d'Asphalte et de Bitume du Centre (SMAC), lasted about a century and contributed significantly to the supply of surfacing materials for major French cities, in particular for paving the sidewalks of Paris.

The Dallet mine consisted of a complex network of underground galleries, which extended over approximately 5 kilometers, organized into several mining levels. The structure of the galleries was reinforced by limestone pillars, a common technique for supporting mining ceilings in this type of rock. The extracted ore was transported by wagons and then by trucks to a processing plant located in Pont-du-Château, approximately 3.5 kilometers from the mine. There, the blocks of bituminous limestone were crushed, heated, and compressed to be transformed into paving stones, which were then shipped to various urban construction sites in France.

From the 1930's, the exploitation of the mine began to slow down due to the progressive exhaustion of the accessible layers. However, a new layer of bitumen was discovered at a depth of 45 meters, and additional equipment, such as a 45-degree inclined plane, was installed to allow the extraction of this resource. Despite these efforts, the exploitation lasted only a few more decades.

The Mine des Rois finally ceased operations in 1984 after a fatal accident, ending a century of intensive mining that had extracted approximately 828,000 tonnes of bituminous limestone, including 58,000 tonnes of pure bitumen. The mine was closed due to the depletion of resources and changing safety standards in the mining sector. A tragic collapse led to the definitive shutdown of operations. Over the decades, mining bituminous limestone had become dangerous due to the dilapidated infrastructure and increasing risks to the safety of miners. This accident highlighted the safety challenges and complexity of extracting materials in conditions that had become too precarious, forcing operators to cease all activity to protect personnel. Today, all entrances to the mine are closed and sealed to prevent intrusions.

Lussatite from Mine des Rois de Dallet, Puy-de-Dôme, France

Lussatite from Mine des Rois de Dallet, Puy-de-Dôme, France

Lussatite from Mine des Rois de Dallet, Puy-de-Dôme, France

Lussatite from Mine des Rois de Dallet, Puy-de-Dôme, France

Geology and mineral resources

Geologically, the galleries criss-cross the marl-limestone strata, revealing clues to the placement and migration of organic matter in the rock. Many fossils were discovered during the mining work (caenoterium, turtles, crocodiles, flamingos, eggshells, gastropods, stromatolites) many of them are now kept at the Natural History Museum in London. It is also the typical deposit for the famous helix ramondi, this famous land snail extremely abundant on the site. It is still very easy to find them on the dumps in front of the mine. You should also know that the galleries cross an old volcano, called "diatreme" consisting of a peperitic breccia (mixture of sediment and fragmented volcanic rock). Mineralogically, this site is also the cradle of the famous lussatite, this variety of opal-CT that we appreciate particularly. Quartz, Calcite, gypsum and microcrystal zeolites (analcime, clinoptilolite) were also encountered.


Today, the galleries are of course no longer accessible, this mine being subject to numerous collapses. The following photos were taken by ourselves during the listing of bats in 2008 and all the samples come from old collections.

Lussatite from Mine des Rois de Dallet, Puy-de-Dôme, France

Lussatite from Mine des Rois de Dallet, Puy-de-Dôme, France

Fossilized flamingo bone on limestone from Mine des Rois, Dallet, Puy-de-Dôme, France

Fossilized helix ramondi snail from Mine des Rois, Dallet, Puy-de-Dôme, France

Savior of the Mine des Rois : the little horseshoe bat !