The study of a large amount of factual material about the formation conditions of gibbsite or boehmite and their mutual transformations in lateritic bauxites allowed us to solve the problem of boehmite formation and its spatial and genetic relationship to gibbsite. The boehmite formation occurred only during the formation of sedimentary-lateritic bauxites from alluvial and lacustrine sediments that underwent bleaching and resilification at the stage of sediment flooding, as well as on bleached bedrock under sedimentary-lateritic bauxites. The most intense boehmite formation occurred at a depth of 20–30 m from the surface and was accompanied by an alumina input, which was realized here in the form of boehmite along with the gibbsite formation due to the hydrolytic decomposition of kaolinite and partially due to the input alumina. In the upper profiles, the recrystallization of bauxites occurs with the replacement of dissolving boehmite with gibbsite, with a decrease in the total Al₂O₃ content and an increase in the amount of crystallization water. In classic lateritic bauxites, the boehmite content is highly insignificant; that is, its formation in them practically does not occur or is very much inhibited.

The recognition of the Fouta Djallon–Mandingo territory as an independent bauxite province is substantiated. It is confined to the morphostructure of the same name within a single geotectonic structure, the sedimentary cover of the Sahara Platform, in the tropical monsoon climate zone in West Africa. The bauxite exploration history, reserve and resource estimates, and production dynamics in the Fouta Djallon–Mandingo province are reviewed.

The general trends and specific features of the effect of the parent rock lithology on the geographic distribution and quality of bauxites in the Fouta Djallon–Mandingo bauxite province are discussed. The parent rock lithology affects bauxite abundance and quality both at the regional (areal) and local scale. More than 99% bauxite deposits and occurrences are confined to structural–stratigraphic complexes of the platform cover. The spatial distribution of poor- and medium-quality bauxites is predominantly controlled by clayey parent rocks (mudstones, siltstones, and silty mudstones), as well as dolerites, Konga diabases, and sometimes gabbro–dolerites, which occur regionally. Local lithological control is provided by local reworked accumulations of bauxite-bearing lateritic mantle destruction products. The main factors of favorability degree of the aluminosilicate parent substratum are its iron index (Al₂O₃/Fe₂O₃) and the quantity and size of quartz grains. Other regional lithological factors are Middle Miocene freshwater sediments of the Sangaredi Group, their epigenetic alteration together with the underlying rocks, and subsequent laterization, producing high- and premium-quality sedimentary–lateritic and infiltration–metasomatic bauxites.

The study of lateritic bauxite by electron microscopy revealed abundant products of interaction between organic matter and minerals. Abundant biomineral films of different genesis and composition were found, including Al, Fe, Al-Fe, Al-Si, Al-Fe-Si, sorbed rare and rare-earth elements (REE). The evolution of these films from amorphous to crystallized and the conversion into druse crystals of gibbsite, hematite, kaolinite etc. was traced. New data were obtained on mineralization of deposits of wood, roots, biofilms and bacteria in tropical conditions. Mono- and multilayer films were identified. Different composition biofilms occurred before and after seasonal monsoon rains. The mineral composition of the films is influenced by micro-local conditions and the introduction of chemical elements, including rare and rare-earth elements, with capillary water during the dry seasons. The products of biomineralization are microscopic in size, but are of universal and global importance to all weathered rocks and associated bauxite deposits.

Results of the hydrogeochemical study of bauxite-bearing lateritic mantles of the Futa Djallon‒Mandingo Province, West Africa, have allowed us to characterize for the first time the pore water of the vadose and infiltration hydrogeological zone. The abundances of major components (aluminum and iron) in the water are shown to be a few orders of magnitude higher than those typical of other water of lateritic mantles. Pore water is proved to be a major factor of the matter redistribution over any bauxite-bearing lateritic profile.

Detailed mapping and prospecting drilling for bauxites in the territory of the Fouta-Djallon Plateau and Mandingo Mountains and the compilation on the succession, lithology, facies, and age of the Mesozoic–Cenozoic deposits of the marginal zone of the Senegal–Guinea Perioceanic Depression have allowed us to correlate and essentially update the scheme of the geomorphologic evolution of the territory of West Africa and to produce the map of planation surfaces. It has been demonstrated for the first time that the base level inverted in the Middle Miocene, and its emergence was responsible for paleogeographic changes and related regional (not local) accumulation of alluvial and lacustrine sediments of the Sangaredi Group, with the subsequent formation of high-grade bauxites with a high content of boehmite. These bauxites were used for the first time as an age indicator in mapping the Middle–Late Miocene stepwise planation surface.