The Paramaca series (Lower Precambrlan) appears to bear the strongest potential for manganese ore and was selected for systematic exploration. The geological map of French Guiana is advanced enough to enable an exploration company to carry out a regional program without need of any previous geological reconnaissance. In the field, exploration is conducted by geologists walking on a regular line pattern, adapted to the local topography and the geological features of a determined region. Photogeological methods are widely applied before and after the field examination. Exploration is completed in the Northern Paramaca belt (between Cayenne and the River Mana) as well as in the P.I. and Ampouman Falls region (between the Rivers Mana and Maroni). At present the Southern Paramaca belt {region of Maripassoula) is under examination, it is planned to extend exploration to the Paramaca formations of the Rivers Oyapok and Approuague. A manganiferous zone was discovered in the region of the Ampouman Falls (Maroni River). This zone is built up of discontinuous lenses of gondites associated mainly with amphibolites, chloritoid schists, and graphic quartzites.