Rees and other critical raw materials in Cretaceous Mediterranean-type bauxite: The case of the Sardinian ore (Italy)

• How different chemical fractionation affect Sardinian Mediterranean-type bauxites. Al2O3 vs SiO2 suggest variability in the epigenetic kaolinite by boehmite replacement. Cerianite micro-spheres and REE-phases are generated oxidising illuvial horizon. R-mode analysis suggests most critical raw materials covary with contents. bauxites could represent a potential source of materials. bauxite deposits Sardinia formed during Upper Cretaceous (Cenomanian–Turonian) due to emergence south European margin Alpine Tethys an area affected monsoonal climate. The were controlled structural frame transpressive tectonic regime unconformably overlie carbonate rocks age composition, which led formation types. In general, deposits, is main Al-phase, Si-rich mineral, hematite as well goethite Fe-rich phases. Secondary authigenic anatase detrital rutile control Ti Eu/Eu* anomalies show that types derived from Variscan basement. However, there differences Al 2 O 3 SiO contents, was localised extent replacement boehmite. factor (as defined devoted Union working group), such Sc, Ga, Nb, Hf, Ta, W, Si-poor bauxite, these metals economic interest likely boehmite, whereas they mostly weathering-resistant minerals. Rare earth element (REE)-rich minerals, including fluorocarbonates cerianite, concentrated basal, horizon, especially silica-rich (?REE = 1006–2034 ppm). required Ce oxidation, fluorocarbonate involved mobilisation trivalent REEs further fluoride complexation. Both REE-rich mineral phases precipitated under alkaline pH conditions near bedrock. Our evaluation distribution coupled “economic importance” “supply risk” parameters, indicate ore contains large amounts characterised risk”, light heavy REEs, importance”, V W. this way, be reconsidered