Clayey deposits of Nanga-Eboko (central Cameroon) were studied to assess their potential as building materials. Characterization was performed using XRD, FTIR, XRF, DTA/DTG and firing testing. Clays appear as discontinuous pockets with the same textural characteristics in three villages located on both sides of the Sanaga River. The average thickness of the exploitable layer is about 3m. The estimated tonnage ∼7–17×10⁵m³can supply a brick industry of great importance. SiO₂(∼70%), Al₂O₃(∼15%) and Fe₂O₃(∼4%) are the predominant oxides of the natural clays. Quartz (∼55%), kaolinite (∼33%), illite (∼5%) and K-feldspar (∼4%) are major minerals. Clays are not suitable for building construction due to their fine-grained size and high plasticity properties. Firing properties of bricks (950 and 1050°C) are good despite the high shrinkage values. Therefore the addition of “degreasers” is recommended to control shaping and drying.

This study investigated the mineralogical assemblage of weathering products developed on mylonite rocks in west Cameroon. Smectite and vermiculite occurrence was studied, particularly to emphasize its origin and the potential of the samples in terracotta production. Samples characteristics were determined through X-Ray Diffraction (XRD) and X-ray Fluorescence (XRF) methods. Weathering products were observed along road trenches of 450 m long and 50 m height on a syenitic basement rock intruded by magmatic rock veins. Clay minerals are mainly composed of kaolinite and illite. 2:1 swelling clay minerals (vermiculite, montmorillonite) occur in some samples mainly originated from the contact between weathering materials and quartzo feldspatic bands. The main oxides are SiO₂ (46–72%), Al₂O₃ (16–31%), Fe₂O₃ (2–16%) and K₂O (0.1–6%). Vermiculite may be formed by fluid-mineral interactions during alteration of the chlorite in the plasmic microsystems of the soil. Structural changes in the upper part of the saprolite leading to the transformation of vermiculite into smectite under supergene alteration control, which predominates in humid tropical zones. Heavy rainfall leads to the formation of kaolinite at the expense of 2:1 clay minerals. Empirical classification revealed that the studied weathering products can be used to produce common bricks.

This study presents a detailed mineralogical and crystallochemical characterisation of clay deposits from Mbengwi (Northwest Region, Cameroon) to evaluate their suitability for industrial applications. Three samples collected at depths of 10.7 m (BGW1), 8.8 m (BGW2) and 6.5 m (BGW3) were analysed using x-ray fluorescence, x-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis and differential scanning calorimetry. Across all sampled depths, high-purity kaolinite consistently dominates the mineralogical composition (∼90%), with minor occurrences of illite (1.5%), quartz (3%), goethite (1.3%) and anatase (1.4%). The SiO ₂ /Al ₂ O ₃ ratio closely aligns with the theoretical value for ideal kaolinite (1.17). The absence of distinct crystalline iron-bearing phases suggests either isomorphic substitution of Fe ³⁺ within the kaolinite lattice or the presence of poorly crystalline iron minerals. Crystallinity indices – including the Hinckley Index, the size of the coherent scattering domain (D), the slope ratio and the FTIR-derived P ₀ and P ₂ factors – indicate a progressive enhancement of structural order with increasing depth. Thermal analyses corroborate this trend: deeper samples exhibit higher dehydroxylation temperatures and sharper endothermic peaks, reflecting least defect density and high kaolinite purity. These findings highlight the superior crystallinity and purity of deeper kaolinitic layers, positioning Mbengwi clays as promising candidates for high-performance applications such as ceramics, paper, catalyst supports and polymer industries.

Herein, Mn3O4 spherical particles (SPs) were synthesized by the sol-gel process, followed by thermal annealing at 400 °C. The sample was analyzed by XRD, FTIR, SEM, SBET, XPS, H2-TPR and UV-vis spectroscopy. XRD and FTIR analysis show that Mn3O4 exhibits a tetragonal spinel structure. SEM and SBET analysis display a porous homogeneous surface made of strongly agglomerated spherical-like grains size with an estimated average particle size of ~35 nm, corresponding to a large specific surface area (SBET) of ~81.5 m2/g. XPS analysis indicated that, Mn3O4 were composed of metallic cations (Mn4+, Mn3+, Mn2+) and oxygen species (O2-, OH- and CO32-). The optical energy band gap energy was ~2.55eV. Moreover, Mn3O4 SPs were successfully tested as catalyst with almost 100% conversion of CH4 to CO2 and H2O at a gas hourly space velocity (GHSV) of 72 000 mL3.g-1h-1. The observed performance can be assigned to the cooperated effects of the smallest spherical-like grain size with mesoporous structure as responsible for the larger SBET, and the available surface-active oxygenated species. The cooperative effect of the good reducibility, the higher ratio of active species (OLat/OAds), as well as Density Functional Theory (DFT) calculations suggested that, CH4 total oxidation over the mesoporous Mn3O4 SPs might follow a two-term process in which both Langmuir-Hinshelwood and Mars-van Krevelen mechanisms are cooperatively involved.