Chemical composition of a manganese crust from Upper Cretaceous formations of the Briançon area in the French Alps

The described sample comes from an outcrop situated in the internal part of the Briançonnais area (Acceglio zone), on the right bank of the high Ubaye valley at 400 m North of the hamlet of Combe Brémond. Two levels of manganese rich and iron rich limestones have been studied and chemically analysed. Rhodonite and pyrosmalite minerals have been identified.