Vieille Montagne is the name of a former zinc mine in Kelmis (La Calamine), a town in Belgium between Liège and Aachen. The mine's name is French for "the old mountain", and this is also reflected in its German name, Altenberg. The mine was once a bone of contention between Germany on the one side and the Netherlands and later Belgium on the other, resulting in the mine and village becoming the neutral territory of Moresnet.
It was first opened in 1805 and continued in operation until the end of the 19th century.
The company opened a second zinc mine in Zinkgruvan in Sweden, which is still in operation. It also ran a harbour in Åmmeberg to ship the zinc.