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Mineralogy of soil kaolinites from Cameroon
Author(s) -
Breuer Jörn,
Murad Enver
Publication year - 1992
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.19921550506
Subject(s) - kaolinite , vertisol , soil water , clay minerals , mineralogy , crystallinity , geology , soil science , goethite , environmental chemistry , chemistry , adsorption , organic chemistry , crystallography
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 Fe 2+ than the corresponding fine clay, which is dominated by smectite. It is conceivable that the Fe 2+ content of the kaolinite reflects the redox environment of the samples.