Clay samples collected from the minesite of Magpet in Cotabato were studied by means of X-ray Dffraction, TG-DTA, IR, SEM, Optical and Chemical analyses. Observations were made on the raw and 2µ >samples as well as on samples fired at 200^oC, 300^oC, 400^oC, 500^oC, 600^oC, 700^oC, 800^oC, 1000^oC and 1200^oC.

Mineral determination by X-ray diffraction showed that comparatively well-crystallized kaolinite and cristobalite are substantially present with small amount of alunite. Scanning electron micrograph of the 2µ> sample revealed hexagonal platy crystals. Heat treated 2µ> sample at 500^oC, showed no change on the crystal structure of kaolinite. However, at 500^oC, comparatively greater decrease in the intensity of the OH stretching vibration in the region 3630 - 3700 cm^-1 was observed. The absorption spectra and X-ray diffraction pattern of 2µ> showed that the kaolinite structure collapsed and Al-Si spinel is formed at about 1000^oC with
exothermic reaction at 988^oC This transformation is composed of a highly ordered development of a spinel-type phase. Subsequently, the spinel was transformed into mullite and cristobalite at about 12000^oC.