People enjoying the blossoming flowers and plants on a stroll through the hilly countryside around La Calamine (German: Kelmis) in the springtime, will come across tender blossoms of yellow violets in certain places. Experts will recognise them immediately as rare botanic species. The viola calaminaria, as it is called, can only survive in the ideal conditions to be found in the area around La Calamine, Moresnet and Stolberg, where the soil is polluted with heavy metals from the old calamine ore mines.
The area around La Calamine (south-west of Aachen) and Stolberg (south-east of Aachen) has its own peculiar geological features. Here, on the edge of the Eifel, the countryside is full of Devon sandstone, slate and limestone, rich in lead, zinc and iron ore. Vieille Montagne near La Calamine was particularly unusual from a geological point of view, since it consisted almost completely of calamine (zinc spar). There is evidence of calamine mining at Vieille Montagne as early as the Middle Ages. Brass was made by processing the ore with copper, and this formed the basis for the widespread growth of the metalworking industry in the Aachen region. Until the end of the 17th century the ore was quarried from open mines and exported all over Europe, even as far as Russia. Starting in the 18th century the miners gradually began to dig away into the ground beneath Vieille Montagne. Gigantic spoil tips of heavy metal rock were piled up – the current biotopes of the "calamine violet".
In 1815 the Treaties of Vienna resulted in a part of the area being divided between the Netherlands and Prussia. But, because of its geological treasures, a small triangle comprising La Calamine and Vieille Montagne, remained a subject of dispute between the two powers for more than a century until 1919. For this reason it was given the status of "the neutral area of Moresnet".
Mining around La Calamine stopped in 1951 and the area around Vieille Montagne has been mostly flattened out as a result of mining activities. But memories remain. The Vallée de la Gueule Museum in La Calamine contains a permanent exhibition on the arduous working conditions which the miners had to endure in digging out the ore. The long and colourful political history of the area is another theme dealt with in the museum. Visitors can see rare exhibits here, like the coins and stamps which were specially issued during the "neutral" period of the area. Fans of geology can enjoy examining the many different minerals to be found in the region. The museum´s programme also includes temporary exhibitions, slide lectures and excursions into the neighbourhood. The star feature, however, remains the hardy survivor, the "calamine violet"!