Emerging frontiers in mineral science emphasize the need for sustainable, low-impact materials that leverage waste resources while delivering functional performance for advanced applications. In this study, agro-industrial waste—specifically rice husk ash combined with excess aluminum sulfate—was transformed into synthetic alkali feldspar particles through a rapid sol–gel process. The resulting powder exhibited an optimal chemical composition of 59.33% SiO₂, 16.42% Al₂O₃, and 7.12% alkali oxides, confirming its successful conversion into a synthetic feldspathic mineral. The product also displayed a high lightness value (L* ≈ 100), indicating a bright white chroma suitable for reflective and thermal management coatings. X-ray diffraction patterns further verified the presence of albite, orthoclase, quartz, and thenardite phases, demonstrating the formation of mixed alkali feldspar and associated phases.

To assess its application potential, the synthesized alkali feldspar was incorporated into a paint matrix and applied to a glass substrate. At a low particle concentration of 1.59%, the coating reduced thermal conductivity to 1.03 W/m·K, whereas a higher particle concentration of 7.90% increased conductivity to 1.68 W/m·K relative to the control substrate of 1.07 W/m·K. Optical microscopy confirmed well-dispersed particles within the coating layer, suggesting favorable compatibility and dispersion behavior.

Overall, the findings highlight waste-derived alkali feldspar as a tunable, sustainable mineral resource with promising applications in energy-efficient coatings, reflective surfaces, and thermally adaptive construction materials—aligning with innovative future opportunities in material resource development.