Mineralogy of soil kaolinites from Cameroon |
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| Authors: | Jrn Breuer Enver Murad |
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| Institution: | Jörn Breuer,Enver Murad |
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| Abstract: | Different particle-size fractions of soil clays from the semi arid north and the humid tropical south of Cameroon have been characterized with reference to their chemical composition, clay mineralogy and kaolinite crystallinity (Hinckley indices). Selected samples were also examined by Mössbauer spectroscopy. Hinckley indices of kaolinites, which were a major component of the coarse clays, varied considerably (< 0.1 - 0.69) and differed significantly as a function of the geographic and landscape positions of the soil profiles. The Hinckley indices averaged 0.31 in soils from southern Cameroon and 0.30 and 0.07 in soils from high and low landscape positions in northern Cameroon, respectively. Kaolinite crystallinity is therefore considered to vary as a function of transport and/or depositional environment of the kaolinite-containing material. Mössbauer spectra showed that kaolinite-dominated Vertisol coarse clays contained higher relative amounts of Fe2+ than the corresponding fine clay, which is dominated by smectite. It is conceivable that the Fe2+ content of the kaolinite reflects the redox environment of the samples. |
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