COMBINED THERMAL AND STRUCTURAL STUDY OF SOME EGYPTIAN BENTONITIC CLAYS

Egyptian bentonitic clays from Qasr El-Sagha, Wadi El-Rayan, Kom Oshim and the Cairo - Alexandria desert road were studied thermally (TG, DT G and DTA) and structurally (XRD and IR). The clay fraction consisted mainly of montmorillonite, kaolinite and some illite. Gypsum, quartz a nd calcite were also identified. It was found that the Na- to Ca-montm orillonite ratio increases in the following sequence: Qasr El-Sagha<Wa di El-Rayan<Kom Oshim<Cairo - Alexandria desert road. There is a marke d concentration of gypsum, the highest amount occurring in the bentoni te from Qasr El-Sagha, and the least in that from the Cairo - Alexandr ia desert road. Calcite was mainly found in Kom Oshim, with a very sma ll amount from the Cairo - Alexandria desert road. Magnesium is more a bundant than iron in the octahedral layer and increases in the followi ng sequence: Cain, - Alexandria desert road<Kom Oshim<Wadi El-Rayan<Qa sr El-Sagha.