Geology and Mineral Chemistry of Uranium‐ and Thorium‐bearing Minerals in Rare‐Metal (NYF) Pegmatites of Um Solimate, South Eastern Desert, Egypt

Abstract

and REEs, and semi-precious colored gemstones such as topaz, beryl and tourmaline (Černý et al., 2012). Furthermore, they also represent the main sources of feldspar, which is used in the ceramics, glass and electronics industries. Pegmatites occur as sharply bounded homogeneous to zoned bodies within igneous or metamorphic host rocks. The current classification scheme uses some of these indicators to group granite pegmatites into five classes: abyssal, muscovite, muscovite-rare element, rare-element, and miarolitic (Černý, 1991; Černý and Ercit, 2005). This scheme is widely accepted, although some researchers have noted a greater diversity in pegmatites and pegmatite gneisses as well as a lack of correlation between depth and geochemistry (Simmons and Webber, 2008). For example, pegmatites in the rareelement class can be grouped into two families based on the principal rare-elements present. Firstly, Lithium-Cesium-Tantalum (LCT) pegmatite, which is identified as a diagnostic association, associated with S-type granites, that can be derived from mature sedimentary sources, for example marine shales. Pegmatites of this type can contain higher concentrations of Li, Rb, Cs, Be, Nb Ta, and Sn, as well as fluxing components such as P, F and B, as reported by Stilling et al. (2006), Simmons et al. (2016 and Liu et al. (2019). Other studies showed that the second Niobium-Yttrium-Fluorine (NYF) association can be used as a trace element signature (Černý and Ercit, 2005;Černý et al., 2012). Normally, NYF family pegmatites show a strong affiliation with A-type (anorogenic environment, lower continental crust ± mantle source) granitic magmas. In an orogen, NYF pegmatites can be spatially close to some Itype (igneous source) granites but they do not show any genetic link. The possibility that I-type magmas can produce NYF pegmatites is very low (Černý et al., 2012). NYF-pegmatites are enriched in Y, REE, Ti, Zr, Nb, Ta, U, Th, and F (Černý, 1991). In addition, a mixed LCT + NYF type, represented in pegmatites with intermediate geochemical signatures, has also been recognized (Černý

Petrogenesis and Geodynamic Evolution of A-Type Granite Bearing Rare Metals Mineralization in Egypt: Insights from Geochemistry and Mineral Chemistry

“…Rare metals mineralization has a markedly wide distribution in granite and associated pegmatite, mylonite, and rhyolite flow tuffs, as well as in lamprophyre and felsite dikes and quartz veins, which could have originated from magmatic and/or metasomatic processes [8][9][10][11][12][13][14]. Rare metal granite is widely distributed in the Eastern Desert (Figure 1b).…”

“…These rocks are subdivided into metaluminous granite (Nb, Zr, and Y rich), peraluminous granite (Ta is the most predominant one, followed by Nb, Sn, W, Be, and Li), and metasomatized granite (Nb is the most abundant, followed by Ta, Sn, Zr, Y, U, Be, and W) [15][16][17][18]. Rare metals mineralization has a markedly wide distribution in granite and associated pegmatite, mylonite, and rhyolite flow tuffs, as well as in lamprophyre and felsite dikes and quartz veins, which could have originated from magmatic and/or metasomatic processes [8][9][10][11][12][13][14]. Rare metal granite is widely distributed in the Eastern Desert (Figure 1b).…”

Excess Lifetime Cancer Risk Associated with Granite Bearing Radioactive Minerals and Valuable Metals, Monqul Area, North Eastern Desert, Egypt

“…It has been recognized that granite, related to pegmatite and acidic volcanics, is a good potential source of uranium, thorium, and other rare metal mineralization [25][26][27][28][29][30][31][32][33][34]. In the last ten years, comprehensive programs for U and Th exploration in the so-called younger granites (post-orogenic granites) of the ED have been carried out.…”

Natural Radioactivity in Soil and Radiological Risk Assessment in Lișava Uranium Mining Sector, Banat Mountains, Romania

“…Uranium is a substantial component of several minerals, the most notable of which are uraninite, brannerite and carnotite. Thorium may be found in a variety of minerals, including thorite and thorianite [12]. Both elements (thorium and uranium) coexist in accessory minerals such as zircon, monazite, apatite, allanite and titanite, which are found in igneous and metamorphic rocks, with zircon and monazite being the most resistant to weathering.…”