Mineralogical and geochimical features of Foumban clays deposits (West-Cameroon): genesis and Potential Applications

Common clay deposits from five localities in Foumban (West Cameroon) were investigated for their morphological, mineralogical and geochemical properties to determine their potential source rocks and suitability in ceramic product. The analytical results were obtained by X-ray diffraction, X-ray fluorescence spectrometry, Thermogravimetric Analysis, Scanning Electron Microscopy, and Fourier Transform Infrared Spectrometry.
Morphologically, an homogeneous clayey layer was found in the upper part of a laterite cover on interfluves, and a clayey heterogeneous hydromorphic material in valleys. They are minerallogically composed of kaolinite (25-84%), illite (0-18%), smectite (0- 31%), and chlorite (0-8 %), associated with quartz (2-44 %), K-feldspars (0-27 %.), plagioclase (0-26%), goethite; (0-9%) with traces of rutile and hematite (≤5 %). The geochemical analysis shows a
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relative large amount of SiO2 (45-71%), Al2O3 (14-31%), and low Fe2O3 (up to 11 %) suggesting weathering of mainly granitic and rhyolitic parent rocks.
Most studied clays could be applied to building ceramic product such as bricks (refractory or not) and tiles. Illite may promote the glassy phase responsible for the densification of the final product. In addition, the relatively high proportion of alkali elements (K2O + Na2O, 6-8%) in some samples from Marom, Koutaba and is responsible for low firing temperature. However the presence of smectite (up to 5 %) limits the application of some Koutaba and Marom clays for ceramic building. The high Fe2O3 contents (> 8 %) in some Bangourain clays implied some pretreatment.