Asselberghs tells us in 1924 "This slate quarry, that was opened around 1884, is today the headquarters of the Herbeumont Great Slate Quarries Company. There is a shaft dug 100m deep into the face of the fault following the course of the gradient. The operation consists of a dozen chambers spread over three levels. On average, the chambers are 30 metres long and 18 to 20 metres high. One chamber is 37.5 metres long. Each level is separated by veins, whose gradient, unlike in the quarry at Neufchâteau, is not perpendicular to the surface. The gradient of the veins is more acute, forming an angle of 60° with the horizontal. This arrangement has implications for the method of extraction used in the chambers, in that the part next to the wall of one chamber is accessed by a gallery at the same level, while the part next to the roof is worked on by the extended gallery at a higher level. The usable vein is 40 to 50 metres deep. It is about 200m long. The bed of rock runs N 83° E and at an angle of S 43°, which possibly corresponds to a stratification joint. If this is the case, the direction of the fault coincides with foliation.

At the turn of the century, this slate quarry was let to a German by the name of Scherke. En 1909, Léontine Pierlot took over once more as Director, followed from 1920 to 1938 by Auguste Pierlot. From 1938 to 1940, production ceased, but restarted from 1940 to 1941 under the management of Mr Wauquez Alphonse from Brussels. Hubert Pierlot then ensured that his brother would take over the management until the quarry closed in 1956.