In 2009, the Tellure mining park created a via ferrata in order to raise awareness about the former mine of Saint-Jean Engelsbourg. It experienced great activity between the 15th and 16th centuries after Collin Schwartz discovered silver veins there. The hardness of gneiss rocks quickly dulled the tips of tools, which had to be replaced every hour. The miners worked an average of eight hours a day, advancing only a few 1.65 ft (50 cm). The galleries dug with this method display walls streaked with scratches. The firing technique, which splits the rock, was also used at that time.