The rock of the Saint-Jean vein in the Tellure mining site consists of gneiss containing a significant proportion of metal-bearing elements. Mainly composed of copper, silver, and lead, the deposit was discovered in 1549 by a miner named Collin Schwartz. The veins widespread in the Val d'Argent's mines contained nearly 150 mineral species, some of them constituting the ores of silver, copper, arsenic, lead, zinc, nickel, and iron. Several veins' residues still outcrop along the via ferrata created in the Colonne Saint-Jean in 2009.