XRD, SEM Characterisation and Economic Potentials of Volcaniclastic-Derived Clays from Ediki, Mungo Formation, SW Cameroon

The Cretaceous Mungo Formation in Ediki, situated in southwestern Cameroon, is characterised by sandstone, siltstone, and carbonates, overlain by pyroclastics and undifferentiated mafic rocks. Clayey occurrences are ubiquitously sandwiched within the sandstones. To determine the clay mineral diversity and commercial applicability, eleven clay samples were obtained through scooping and analysed by XRD and SEM methods. XRD results show kaolinite (NK1, NK2, NK4, NK6, NK7, NK8), halloysite (NK3, NK5, NK11), and illite (NK9) as major clay phases, while montmorillonite, feldspar, and quartz are associated with the clay. Magnetite, hematite, and ilmenite occur as impurities. Gibbsite is recorded in one sample (NK10). SEM reveals that the kaolinites are flat, plate-like, and lotus-like; halloysite is spongy, rod-like, and pseudo-spheroidal, while illite is scallop-shaped. The gibbsite sample is stalactitic. The clays are derived from the decomposition of the pyroclastics, ash, and ultramafic and mafic rocks. The iron oxide impurities are from mafic rocks, while quartz is derived from sandstone and siltstone. The occurrence of gibbsite indicates deep weathering in a warm, humid climate. Kaolinite and illite have potential use in ceramics, paper, and as components in cosmetics and toothpaste; montmorillonite and halloysite, as drilling fluids, catalysts, and adsorbents for environmental remediation, drug delivery, and to create stronger nanocomposites.