THE CHEMICAL COMPOSITION OF THE THORIUM ORTOSILICATES FROM ALBITITES OF THE NOVOOLEKSIIVKA THORIUM-URANIUM OCCURRENCE (UKRAINIAN SHIELD)

Summary The chemical compositions of pneumolithic-hydrothermal Thorium orthosilicates from the albitites of Novooleksiivka occurrence are characterized by admixture of Uranium, Rare Earths elements, Yttrium, and some Phosphorus. Thorites and Uranothorites have been identified in albitites. Ferritorites are epigenetic minerals. The chemical compositions of Thorium orthosilicates from the albitites are characterized by admixture of Uranium, Rare Earths elements, Yttrium, and some Phosphorus, which gives the basis for these minerals due to the decomposition of magmatic Monazites of the original rocks. The spectra of Rare Earth elements of Thorium orthosilicates are not constant, which is a sign of the fractionation of these elements in the processes of pneumolithic-hydrothermal alteration of the original rocks. The signs of the Uranium and Thorium leaching, migration and deposition testify of the existence of conditions of transportation of Uranium in the U4+ uranium oxidation state in the fluid, that generated rocks.