Manganese Mineralizations of West Africa: Geology, Genesis and Distribution

In this review paper, we present the compilation of research work carried out on eight (8) manganese mineralizations, which represent the main manganese mineralizations of the West African Craton (WAC) and its surrounding areas. These Mn mineralizations were selected based on bibliographic availability and the importance of their grade and extend. A compilation of data from outcrop description and mineralogical analyses allowed to highlight the emplacement of mineralizations, their origin and evolution within the WAC. These analyses made possible to make comparisons between the different manganese mineralizations. Depending on the periods of emplacement, at least two contexts emerge: (i) the manganese mineralizations which are hosted in the Mesozoic dolomites, like Imini and Bouarfa (Morocco) manganese mineralizations, (ii) and the Paleoproterozoic manganese mineralizations which are located in volcano-sedimentary rocks of greenstone belts: this is the case of the manganese mineralizations of Téra (Niger), Nsuta (Ghana), Mokta (Côte d'Ivoire), Tambão-Beliata (Burkina Faso) and Ansongo (Mali). The main manganese oxides noted at Imini are pyrolusite and the hollandite group (cryptomelane, hollandite and coronadite) while pyrolusite-manganite-hausmannite are preponderant at Bouarfa manganese mineralization. Mineralogically, the Mokta and the Téra mineralizations are close and show little or no rhodochrosite in the primary manganese minerals which are composed of manganese-bearing silicates (spessartine and braunite), whereas rhodochrosite is dominant in the other Paleoproterozoic mineralizations (Nsuta, Tambão-Beliata and Ansongo).