Carriere souterraine de Gèromont

Carrière souterraine du Petit Banc - Underground Quarries of Gèromont

Useful Information

Location: Near Comblain-au-Pont. (50.4306°N 3.9786°E)
Open: Only by reservation, minimum 15 persons.
Fee: Groups (15+): Adults EUR 7, Children (4-11) EUR 5.50, Children (0-3) free.
Classification: SubterraneaRock Mine ExplainRoom and Pillar Mining
Light: LightIncandescent Electric Light System
Guided tours:
Address: Carrière souterraine du Petit Banc, Carrières de Gèromont, Gèromont 105, 4170 Comblain-au-Pont.
ASBL Les découvertes de Comblain, Place Leblanc 7, 4170 Comblain-au-Pont, Tel: +32-4-3692644. 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.


1918 begin of quarrying at Petit Banc.
1935 Roussel family begins underground mining at Grand Banc.
1966 mining ended.


At Comblain-au-Pont, where the river Ourthe flows into river Amblève, a sandstone cliff above the river Ourthe is full of abandoned mining tunnels. The best sandstone in the region was excavated here, used for pavements in many towns in the area. The 370 Million years old sandstone is very hard because of its high quartz content and thus ideal for heavy use. The 1.5 m to 8 m thick layers were deposited in the sea. The rock was discovered at the surface outcrop, but soon the quarrying went underground following the layers at a dip of 20°. Classical room and pillar technique resulted in a labyrinth of passages crossed by other passages, which continues for kilometers.

The Carrière souterraine du Petit Banc is a small part of this huge mine, where a 2 m thick layer of Famennian sandstone was mined during the 1960s. The main chamber has a size of 500 m by 150 m with hundreds of pillars.

The rock is mined by 20 workers which are called haveur (shearer). Then there are refendeurs (splitters) and épinceurs (pinchers) who cut the rock into cobblestones. The workers were payed by the piece and produced some 160 cobblestones daily, however, the number depended strongly on the type and size of cobblestone. 67 different sizes of cobblestones were produced. The most common were perluzettes (flat pavers) of variable dimensions, mosaïques (mosaics) of sizes 5/7 cm, 6/9 cm and 9/11 cm, platines (plates), pavés de route (road blocks) 14/16 cm, and pierres d'angles (corner stones). The rocks were then loaded on a carriage which was pulled out on its rails by a winch.

The sales were pretty well immediately after World War I, but went down with the world economic crisis. The were up again in 1946, but the post war demand receded in the 1960s and so the mines were finally closed in 1966.

The village Gèromont is located on the plateau above river Ourthe. The quarries are located at the escarpment, close to the surface, and offer a great view into the valley and the geologic situation. Tours are operated by the tourist office at Comblain-au-Pont which for some reason is named Les découvertes de Comblain. Unfortunately there are no open hours for individuals, only tours after reservation for at least 15 persons. They once had a daily tour at 14 during JUL and AUG, but this seems to be discontinued. [2020] This may be a result of Corona, so we recommend to check by email or phone when you actually plan to go.