Probability of Kaolinitization of montmorillonite under certain soil conditions of Egypt

摘要

Probability of the sequential development of kaolin by alteration of montmorillonite involving kaolin-montmorillonite interstratification as an intermediate stage of kaolimitization process is described in some Torrifluvents in Egypt.Previous mineralogical studies on a Torrifluvent samples in Egypt showed no or a broad but small peak between kaolinite and montmorillonite peaks (about 7.5Adeg) through X-ray diffraction studies. Some researchers describe this peak due to the presence of Halloysite. However, the obtained results suggest that this peak probably due to interstratified kaolinite-montmorillonite as the intermediate stage of kaolinitization process. This process may take place after building the High Dam. Mineral composition was studied using X-ray diffraction analysis (XRD), differential thermal analysis (DTA) and scanning electron microscope (SEM). Obtained results support the presence of random interstratified kaolinite-montmorillonite during the transformation of montmorillonite to kaolinite, therefore, the weathering sequence could be suggested as follows: Montmorillonite->random interstratified kaolinite-montmorillonite->Kaolinite + iron oxide. Mechanism of intermediate stage formation is described in details.