CONTRIBUTION TO THE MINERALOGY OF EL SELA URANIFEROUS SHEAR ZONE, SOUTHEASTERN DESERT, EGYPT

El Sela area is one of the most important localities for uranium mineralization in the granites of the southeastern Desert of Egypt. Radiometric analyses for the light and heavy fractions from composite mineralized channel samples collected from the kaolinized granite proved the presence of high uranium concentration in both fractions. The light fraction represents about 84.80% by weight of original sample, containing an average of 26.90% of the total uranium present in these samples. Detailed microscopic examination, X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) were used to identify and characterize the uranium bearing –minerals responsible for the radioactivity in both heavy and light fractions of the studied samples. The heavy fraction (15.2 wt %) is characterized by the presence of secondary uranium minerals (lead-meta-tautunite and phurcalite) together with zircon. In addition of non-radioactive minerals (fluorite, apatite and titanite) are recorded. On the other hand, the high radioactivity of the light fraction is mainly attributed to the presence of secondary uranium minerals coating the light minerals and most probably to the adsorption of hexavalent uranium onto clay minerals (kaolinite) resulting from alteration of feldspars. This mode of occurrence of the uranium must be considered during mineral processing whether by physical or direct hydrometallurgical treatments.