Mining developed in the Black Forest due to its ore deposits, which were often lode-shaped. The formation of these deposits (Schauinsland Pit: zinc, lead, about 700-1000 g silver/ton of lead; baryte, fluorite, less lead and zinc in the Kinzig valley; BiCoNi ores near Wittichen, uranium discovered in the Krunkelbach valley near Menzenschwand but never officially mined) often used to be linked to the intrusion of Carboniferous granite in the para- and orthogneisses. More recent research has revealed that most of these lode fillings are much younger (Triassic to Tertiary). Economic deposits of other minerals included: fluorite in the Northern Black Forest near Pforzheim, baryte in the central region near Freudenstadt, fluorite along with lead and silver near Wildschapbach, baryte and fluorite in the Rankach valley and near Ohlsbach, in the Southern Black Forest near Todtnau, Wieden and Urberg.