The working and the treating of iron are a very old human activity. The excavations carried out in the keep of Usson under Patrice Tillet's management have demonstrated that there was an activity of iron treating on the site, probably aimed at military and civilian use. Small « home » forges were in activity in the keeps and other fortified sites. In 1714, the Marquis de Bonnac, Jean-Louis d'Usson, was allowed by King XIV to build a forge according to the Catalan manner on the territory of Mijanès . It worked till 1840 ; in 1814, the production sent to the Departments of Haute-Garonne and Aude was of 874 quintals of iron.