Mineralogical analysis of the bauxitic profile of Canonnettes using X-ray diffraction, electron spin resonance (ESR) and infra-red spectrometry shows that the kaolinites contain structural iron. As the amounts of Fe- and Al-oxyhydroxides increase in the profile, the proportions of AlOOH in the goethite structure and iron in the kaolinite structure increase and the kaolinite also becomes more disordered. Ultimately, kaolinite is completely replaced by Fe-oxyhydroxides (goethite + hematite) and Al-hydroxides (gibbsite+boehmite).

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