This study presents a comprehensive geochemical, mineralogical, and microstructural evaluation of clay deposits from Isuochi (Samples A and B) and Ihube (Samples C and D), Southeast Nigeria, to determine their suitability for sustainable refractory applications. Integrated XRD, XRF, and SEM–EDS techniques were employed to quantify mineral phases, major oxides, and microstructural characteristics. Results show that all samples are dominantly aluminosilicate clays, composed mainly of SiO₂ (46.12–70.32 wt%) and Al₂O₃ (24.47–33.69 wt%), with minimal fluxing oxides (CaO, MgO, K₂O). XRD analysis reveals significant proportions of quartz (44–62%), feldspars (14–27%), kaolinite/dickite (up to 32%), muscovite/illite, and chlorite, indicating varying degrees of sedimentary and low-grade metamorphic alteration. SEM–EDS confirms these findings, showing heterogeneous but coherent microstructures indicative of good firing stability. Samples A and C exhibit high silica–kaolinite purity ideal for ceramic and glass applications, while Samples B and D, enriched in accessory phases such as anhydrite, muscovite, and clinochlore, demonstrate enhanced thermal resistance suitable for refractory linings. The combined SiO₂–Al₂O₃–Fe₂O₃ content (78–96%) meets ASTM criteria for natural pozzolanic and refractory-grade materials. Overall, the Isuochi–Ihube clays exhibit excellent mineralogical and chemical attributes for high-temperature engineering applications, offering a viable local alternative to imported refractories and contributing to sustainable materials development in Nigeria.

Clay; Aluminosilicate; Geochemical; Pozzolanic; Refractory

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