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The presence of halloysite in the young soils above the basalts of Central Cameroon Three profiles of young soils formed on the basalts of Central Cameroon were studied. After a short description of the soils and some analytical data, the clay fraction of the soil is considered in more detail, The clay minerals found were halloysite and metahalloysite, the first appearing to give rise to the second, The clay fraction was studied by chemical, thermal and X-ray analysis, microscopy and electron diffraction, The structures observed may be likened to the "onion-like" allophane-halloysite of Japanese authors, Trois profils de sols jeunes sur des basaltes du Centre Cameroun sont étudiés. Après une brève présentation des sols et quelques indications analytiques l'étude de la fraction argileuse est abordée plus longuement, par voie chimique, thermique, rayons X, microscopie et microdiffraction électroniques, Les minéraux argileux mis en évidence sont l'halloysite et la métahalloysite, la première semble engendrer la seconde. L'halloysite & présente sous forme de particules allongées ou de glomérules., Sieffermann Gaston, Millot Georges. L'halloysite des sols jeunes sur basaltes récents du Centre Cameroun. In: Bulletin du Groupe français des argiles. Tome 20, fascicule 1, 1968. pp. 25-38.

From a study of the distribution of the total trace-element content of 18 profiles in Cameroun, belonging to 6 different classes, the following conclusions have been reached: 1. (1) The zone of influence of the parent material is constituted by the weathering horizons (BC and C). 2. (2) The zone of influence of the pedogenetic factors is constituted by the horizons of the “solum” (A and B). 3. (3) Each soil-type exhibits its own geochemical character which may be expressed as the sum of the total content of trace elements with the same physico-chemical behavior. The results of quantitative spectrographic analyses of the 14 most common trace elements as observations on the pedogenetic factors which may be responsible for their distribution have been set out in four profiles: a ferralitic red soil; a ferruginous tropical soil; a brown soil; and a planosol.