Radioactive mineralizations on granitic rocks and silica veins on shear zone of El-Missikat area, Central Eastern Desert, Egypt.

The shear zone of the El-Missikat area is considered one of the most important occurrences of uranium (U) mineralization in the Central Eastern Desert of Egypt. This shear zone is characterized by a tabular elongated zone of crushing and brecciation resulting from many parallel fractures or intense jointing, and presence of silicification and other alteration products together with the occasional presence of U mineralization. The concentrations of the natural radionuclides were measured by Sodium Iodide Detector NaI (Tl) in 87 granitic rocks and silica veins collected from the Central Eastern Desert. Measurement of radioactive elements suggests U present in granite of the El-Missikat pluton as well as in red, black and jasperoid silica veins. Radioactive mineralization was determined by scanning electron, binocular, and polarizing microscopies. The mineralizations are represented by syn-genetic U-leaching origin accompanying granitic rocks and post-magmatic association in red and black silica veins. The U-host mineralizations are mainly represented by radioactive minerals such as uranophane, kasolite, and U-bearing zircon.

Element Accumulation Patterns of Native Plant Species under the Natural Geochemical Stress.

A biogeochemical study of more than 20,000 soil and plant samples from the North Caucasus, Dzungarian Alatau, Kazakh Uplands, and Karatau Mountains revealed features of the chemical element uptake by the local flora. Adaptation of ore prospecting techniques alongside environmental approaches allowed the detection of geochemical changes in ecosystems, and the lessons learned can be embraced for soil phytoremediation. The data on the influence of phytogeochemical stress on the accumulation of more than 20 chemical elements by plants are considered in geochemical provinces, secondary fields of deposits, halos surrounding ore and nonmetallic deposits, zones of regional faults and schist formation, and over lithological contact lines of chemically contrasting rocks overlain by 5-20 m thick soils and unconsolidated cover. We have corroborated the postulate that the element accumulation patterns of native plants under the natural geochemical stress depend not only on the element content in soils and the characteristics of a particular species but also on the values of ionic radii and valences; with an increase in the energy coefficients of a chemical element, its plant accumulation decreases sharply. The contribution of internal factors to element uptake from solutions gives the way to soil phytoremediation over vast contaminated areas. The use of hyperaccumulating species for mining site soil treatment depends on several external factors that can strengthen or weaken the stressful situation, viz., the amount of bedrock exposure and thickness of unconsolidated rocks over ores, the chemical composition of ores and primary halos in ore-containing strata, the landscape and geochemical features of sites, and chemical element migration patterns in the supergene zone.