Mineralogy of polymetallic mineralized pegmatite of Ras Baroud granite, Central Eastern Desert, Egypt

Abstract

An economically important rare-metal mineralization is recorded in the pegmatite bodies of Gabal Ras Baroud younger granitic pluton, Central Eastern Desert of Egypt. These pegmatite bodies are of variable size and are compositionally zoned. Radiometric measurements of some anomalous pegmatite samples show that their equivalent uranium (eU) content is 219-328 ppm, whereas their equivalent thorium (eTh) content is 783-1101 ppm. On the other hand, the analysis of several separated mineral grains of some pegmatite samples using a scanning electron microscope and X-ray diffraction revealed the presence of several economic minerals. These minerals include zircon, thorite, phlogopite mica, and columbite, in addition to the samarskite-Y mineral. Thorite was found as numerous inclusions of variable size and pattern in zircon. Electron microprobe analysis confirmed the presence of samarskite-Y whose composition corresponds to the empirical formula [(Y0.49, REE0.41, Th0.06, Si0.05, Ca0.03, U0.02, Fe0.01, Zr0.00)Σ1.05(Nb0.75, Ta0.17, Ti0.01)Σ0.94O4]. Accordingly, the mineralized Ras Baroud pegmatite can be considered as a promising target ore for its rare-metal mineralization that includes mainly Nb, Ta, Y, U, and REE together with Zr and Th.