Former Career of On

From here, you will see a cliff rising on the other side of the Wamme. This marks an historic spot for the village, the former On limestone quarry, which began operating in the 19th century, to serve the construction
of the Brussels-Luxembourg railway line (1850). A number of different owners operated the quarry prior to
its acquisition by L. Lhoist in 1924, who expanded and modernised the plant. Since his day, the quarry is no
longer used to produce limestone, but houses the lime kilns vital to the production of quicklime from limestone. Every years, 400,000 tonnes of quicklime are shipped out by truck or freight train, mainly to clients in the steel industry or for use in environmental protection. The On-Jemelle site employs 105 people directly. The kilns are supplied with Frasnian limestone from the Boverie quarry on the other flank of the Calestienne to the north.