REEVALUATION OF KAOLINITE OCCURRENCE IN SOME TORRIFLUVENTS IRAQI SOIL

Clay fraction of Torrifluvents Iraqi soils contained different clay mineral groups. Usually, samples with limited number of clay minerals, can be defined mainly by x-ray diffraction analysis. Whereas poly-mineralized soil needs additional techniques to clarify its mineral composition accurately. Kaolinite which is characterized by reflection peaks at 7.2 Aº and (3.55-3.57 Aº), are normally overlapped with those of chlorite peaks. This work was carried out to reevaluate the occurrence of kaolinite in some Iraqi soils with the presence of chlorites. Clay fractions from four Torrifluvents Iraqi soils were used in this study. X-ray diffraction analysis with different heat treatments is referred to the presence of kaolinite and soil chlorite. Intercalation with dimethylsulfoxide, after saturation with Li (Li-DMSO) showed the presence of a peak at 11.3 Aº, which confirmed the presence of trace amount of kaolinite. However, the continuous occurrence of the peaks at 7.2 and 14.4 Aº are referred to the presence of chlorites. Reduction the intensity of 7.2 Aº peaks by heating at temperature below 500o C confirmed the presence of soil chlorite which overlap with kaolinite. There was no difference among the four soils with regard to the presence of soil chlorite and kaolinite.