Conditions and principal geochemical trends in the formation of bauxite-bearing lateritic mantles are considered on the example of Fouta Djalon-Mandingo Bauxite-bearing Province as the best natural model. Input and output dynamics of petrogenic components was calculated on the isovolumetric base and the obtained data were used to interpret the zoned structure of weathered profile as resulting from its hydrogeological and gas regimes. Although Al separates from Fe in the formation of bauxite horizon, three-valence iron is a typomorphic element of the lateritic landscape as a whole, with 50% Al leaching from lateritic mantle.