Ardoisalle 1947 - Ardoisalle Slate Mine

Useful Information

Location: 12, rue de Reposseau, B-5550 Alle-sur-Semois.
From North follow N 95 or N89 south, wher they meet follow N 819 west to Alle. From Sedan in France D6 leads north to Alle. In Alle at the southern end of the main road, signposted.
(49.837272, 4.967107)
Open: APR to OCT Sat, Sun 10-16:30.
During School Holidays daily 10-16:30.
Reservation mandatory.
Fee: Adults EUR 9, Children (6-11) EUR 7, Children (0-5) free, Students EUR 8.
Groups (10+): Adults EUR 7.50.
Classification: MineSlate Mine
Light: LightIncandescent Electric Light System
Dimension: T=10 °C.
Guided tours: Museum: self guided.
Mine: D=45 min. Français - French Nederlands - Dutch English
Photography: allowed
Accessibility: no
Address: Ardois'alle, 12, rue de Reposseau, B-5550 Alle-sur-Semois, Tel: +32-497-45-43-74. 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.


1870 slate mine opened.
1948 mine closed.
1990 opened to the public.
2012 mine reopened by Vincent Theret.


The slate basin of Alle sur Semois and Rochehaut has three exploitable layers of slate: Laposte, Hour, Laviot.


Ardois'alle is an abandoned slate mine, one of several in the valley of the Semois river, which was closed in 1948. It was formerly also known as Ardoisalle 1947 or simply as Ardoisalle Slate Mine. Today the extraction and exploitation of slate has virtually disappeared in the whole area. This mine was reopened as a show mine with underground tour, which takes about 45 minutes. Good walking shoes and a jacket are recommended.

In the affiliated slate museum, displays a video which tells about the mining of slate. It also has a collection of account books, tools, photographs, and workers' personal effects. In parallel, it has an art exhibition, sculptures made of slate and a collection of slate design objects created by Vincent Theret, who reopened the mine in 2012.

There is also a Mine Tavern, which may be visited independent of the museum and show mine. It's also possible to rent the mine tavern, to celebrate a birthday, a retirement, organize a meeting, or a business meeting. The souvenir shop sells items made of slate. The site is run by a group of volunteers from the village Alle.

Its unknown when the slate mining in the area started, but it seems clear that slate mining is a Belgian invention. One of the oldest known sites in the territory of Alle is the quarry at Les Moines, or Petit Monceau (Small Mountain) slate quarry. According to local lore, it was named to perpetuate the memory of the monks of Laval-Dieu, an abbey located in Monthermé, who devoted themselves to this industry. However, there is no proof, neither documents nor archaeological evidence. Another quarry was opened in the 1820s by Hoffbauer from Sedan in France, who undertook several surveys and began work on one of the most important sites, located in Rochehaut, the Laviot slate quarry. The Adolphe Chastel, also French from Balan, opened the Reposseau slate quarry. The slate quarry of Laplet, was founded by a local, Balthazar Hoffmann. There were numerous quarries opened and closed, about twenty sites in the territory, the last operation to cease all activity was the Reposseau slate quarry, in 1948.

The reopening of a local quarry as a tourist mine was the idea of a local school pupil, Yves Crul, in 1985. He wrote a tourist development project centered on the redevelopment of an old slate site with several friends. The project had two parts, first organizing the underground visit of the mine, after it had been made safe, and the development of a reception and a museum space. The project was presented to the “Heritage” competition of the Fondation Roi Baudouin (King Baudouin Foundation). It was rewarded and then realized with the support ba the municipality.

The mining at the site was restarted in 2012 by Vincent Theret, an artist. He is again mining slate for various purposes. This includes flooring and roofing, but also household items and artworks.

There is a tourist route across the Ardennes, which is dedicated to the slate mining history and named Route De L’Ardoise (Slate Route).