This work discusses the physical, geochemical and mineralogical characterization of some kaolin resources in Sinai which are hosted in thick sandstone sequences belonging to the Lower Cretaceous Malha Formation. The characterization of kaolin samples was done by microscopic, SEM, XRD and ICP-MS analyses. The studied kaolin resources consist of kaolinite as the chief clay mineral of all the analyzed samples. Dickite and/or halloysite are subordinate TO clay minerals, whereas illite and smectite are occasionally encountered as minor clay constituents while the identified non-clay minerals include; quartz, gypsum and hematite. Ferrugination occurs mostly at the upper boundaries of the kaolin lenses in contact with the overlying sandstone beds suggesting a possible supergene activity. The high Al2O3/SiO2 ratio of 0.53 indicates the high quality of Cretaceous kaolin deposits in Sinai. The kaolin of the lower lens in Rueikna and upper lens in Salia contains Si/Al molecular ratio of 0.9 which suggests a high grade of kaolin in these two lenses. The Cretaceous kaolin is characterized by a higher contribution of LREE (Monazite signature). In spite of the very high CIA index (97.4 and 99.2), suggesting extensive limits of chemical weathering, none of the analyzed kaolin deposits displays Ce abnormality.
The Lower Cretaceous kaolin of Sinai does not satisfy the international standards for paper making industries and refractory manufacturing, but beneficiation may overcome this challenge. However, some lenses have high-grade kaolin with a low percentage of iron oxides, magnesium oxides, sodium oxides, calcium oxides and Potassium oxides and a low radioactivity, hence nominated for the local refractory industry. The high-grade kaolin of Sinai fulfills the standards required for ceramic manufacturing in the global market and all kaolin lenses of the study areas can be used in ceramic manufacturing locally.