Mineralogical and geochemical features of ore-bearing pegmatites from Shevchenkove and Kruta Balka deposits (East-Ukrainian pegmatite province)

Ukrainian Shield is a pegmatite province. Only within the East-Ukrainian pegmatite province, thousands of pegmatite bodies of various composition, structure, geochemical and ore specialization were discovered, which are associated with three deposits of rare metals (Shevchenkove — lithium, Kruta Balka — lithium, tantalum, niobium; Mohyla Visla — zirconium, rare-earth elements). It can be assumed that several rare metal deposits of pegmatites yet remain undiscovered. However, at the moment of insufficient funding for geological exploration work, it is impossible to apply high-costly methods of geological surveying and searching. We need low-costly and, at the same time, highly effective methods of research, which could give a reliable characteristic that would indicate their prospects for rare metals when obtaining single cross-sections of pegmatite bodies. The article examines one of these directions — the study of the geochemistry of minerals, in particular microcline, and the materials of study of this mineral from the pegmatites of the Shevchenkove and Kruta Balka deposits are provided. The most widely used variation diagrams for microclines were analyzed: in K : Cs — Na2O coordinates according to V.V. Gordienko, 1970 and 1976; Rb — K : Rb according to the scheme of S.G. Shavlo, 1984 and diagram by O.P. Kalyta. It was found that these diagrams reliably classify pegmatites of the lithium-tantalum specialization of the Kruta Balka deposit, but they are not very informative for the Shevchenkove deposit, that is, for the prediction of specifically lithium deposits. The authors came to the conclusion that the analyzed charts for pegmatites of the Ukrainian Shield need significant revision, both on a significantly larger number of analyzes and taking into account the location of sampling, especially in the unproductive part of the pegmatite.