The Saint-Jean vein in Tellure Park consists of gneiss rocks containing a significant proportion of metal-bearing elements. Discovered in 1549 by a miner named Collin Schwartz, the deposit is mainly composed of copper, silver, and lead. In total, the veins widespread in the walls contain nearly eighty mineral species constituting the ores of silver, copper, arsenic, lead, zinc, nickel, and iron. A via ferrata allows observing the rocks closely and understand the silver fever that struck the region.