Mineralogy of polymetallic mineralized pegmatite of Ras Baroud granite, Central Eastern Desert, Egypt (original) (raw)
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Uncommonpresence of rare-metal mineralization is recorded in the mineralized pegmatite injectedin Wadi El Sheiholder granitoids at the central Eastern Desert of Egypt. The studied mineralization was found as distinguishable megascopic crystals of economic minerals scattered within the pegmatiticbodies. Detailed mineralogical and chemical investigation were carried out using microscopic examinations, x-ray diffraction (XRD),scanning electron microscope (SEM) providing with energy-dispersive spectrometer (EDS) and x-ray fluorescence (XRF). These studiesrevealed the presence of several valuable minerals such aseuxenite-(Y), fergusonite-(Y), allanite-(Ce) and xenotime-(Y), in addition touranothorite and zircon.Accordingly, the mineralized Wadi El Sheih pegmatite can be considered as a promising target ore for its rare metal mineralization that includes mainly Nb, Ta, Y, U, Thand REE together with Zr and Hf.
Mineralogy of Mineralized Pegmatite of Ras Mohamed Granite , Southern Sinai , Egypt
2017
An economically important rare-metal mineralization is recorded in the mineralized pegmatite injected in alkali-feldspar microgranite of Gabal Samma at North Ras Mohammed granitic pluton, Southern Sinai, Egypt. The studied mineralization was found as distinguishable megascopic crystals scattered within the pegmatitic bodies of Gabal Samma granite and reach up to tens of centimeters. The mineralogy and geochemistry of the studied rare metal mineralization were determined using microscopic examination and X-ray Diffraction (XRD) as well as scanning electron microscope (SEM). These minerals include a unique occurrence of colored ishikawaite (uraniumrich samarskite) together with fergusonite-Y, allanite, titanite, zircon-thorite association, uranothorite and fluorite. The obtained SEM data for the studied minerals are showing the compositional limits of these minerals as specified in the literature. The occurrence of colored ishikawaite varieties (light brown, reddish dark brown and dar...
The studied pegmatite bodies represent a part of the basement rocks at the South Eastern Desert of Egypt. They are found as lenticular pocket and sheet-like bodies. Ground radiometric survey for some pegmatite bodies within Gabal Al Farayid granite revealed the presence of abnormal radioactivity. Radiometric analysis for anomalous pegmatite samples show that their equivalent uranium content (eU) ranges between 20 ppm and 200 ppm, while their equivalent thorium (eTh) varies from 83 ppm to 587 ppm. Petrographically, the studied pegmatite bodies consist essentially of quartz, k-feldspar, plagioclase and flakes of mica. Monazite, zircon, apatite, fluorite and opaques are accessories. Detailed microscopic investigations, X-ray diffraction (XRD) and Environmental Scanning Electron Microscope (ESEM) were used to identify the present heavy minerals as well as radioactive minerals. These studies revealed the presence of thorite, monazite, garnet (spessartine), magnetite and mica (fluoro-phlo...
Geosciences Research
Lithologically, the rock types of G. El Fereyid-W. Rahaba area are dominantly granites associated with pegmatites. The granitic rocks comprise tonalite and monzogranite with (minor acidic dykes), quartz and pegmatites occur as a vein type (granitic and perthitic pegmatites) hosted within the monzogranite. Structural analysis shows the presence of a prominent set of folds with axes striking WNW to NW and a less prominent set with pronounced ENE and NNW trends. Petrochemical studies and tectonic discrimination diagrams for the monzogranite reveal that it is classified as post orogenic granites (POG). Geochemically, monzogranite shows enrichment (peaks) of large ion lithophile elements (LILE; Pb, Rb, Ba, Sr) and high field strength elements (HFSE; Y, Zr, Nd,) and depletion (troughs) of K, P and Ti. Pegmatite shows enrichment (peaks) of large ion lithophile elements (LILE; Pb, Rb, Sr) and high field strength elements (HFSE; Y, Zr, Th, U, Nb) and depletion (troughs) of K, P and Ti. They exhibit high K-calc alkaline magma and peraluminous characteristics and considered as post orogenic granites (POG). The monzogranite reveal small to moderate negative Eu anomaly, while the pegmatites reveal moderate to large negative Eu anomaly. The pegmatite displays clear W-type tetrad effect of the REE while, the studied monzogranite do not show tetrad effect.
Mineralogy and radioactivity of pegmatites from South Wadi Khuda area, Eastern Desert, Egypt
Chinese Journal of Geochemistry, 2010
Radioactive minerals in pegmatites associated with granitic rocks are commonly encountered in the south of the Wadi Khuda area and found as dyke-like and small bodies. They are observed within garnet-muscovite granites near the contact with older granitoids. Field surveys indicated that the studied pegmatites vary in dimensions ranging from 2 to 10 m in width and from 10 to 500 m in length. They are composed mainly of intergrowth of milky quartz, reddish-pink K-feldspar and plagioclase together with small pockets of muscovite. Field radiometric measurements indicated that radioactivity in pegmatites is more than twice that of their enclosing country rocks. Radionuclide measurements revealed that the average contents of U and Th increase gradually from rocks of dioritic to granodioritic composition (1.5×10−6 U and 4.3×10−6 Th) and increase significantly in biotite granites (5.8×10−6 U and 15.2×10−6 Th) but drastically decrease in muscovite granites (2.2×10−6 U and 5.6×10−6 Th). The average contents of U and Th of anomalous pegmatites are 95.3×10−6 and 116.9×10−6, respectively, indicating their uraniferous nature. In the south of the Wadi Khuda area, pegmatites are low in average Th/U (1.4) and high in average U/K (35.6), which suggests that uranium concentrating processes did not affect the pegmatites, indicating poor source-rocks. Mineralogical investigations of the studied pegmatites revealed the presence of secondary uranium minerals (kasolite and autunite), in addition to zircon, thorite, apatite, garnet and biotite. Primary and secondary radioactive mineralizations indicated that the mineralization is not only magmatic, but also post-magmatic. Electron microprobe analyses showed distinct cryptic chemical zoning within thorite where UO2 decreases from core to rim. This feature in thorite is sporadic, suggesting non-uniform redistributions of UO2 within thorite during magmatic processes.
2021
Article history: Received 1 April 2021 Received in revised form 15 April 2021 Accepted 15 April 2021 Available online 17 April 2021 Rare-metals and rare earth mineralization has been observed in Wadi El Sheih older granitoids bearing uncommon mineralized pegmatite. This type of mineralization was recorded as distinguishable mega-crystals scattered within the pegmatite. Detailed mineralogical investigation was carried out using different analytical techniques as: microscopic examinations, x-ray diffraction (XRD), and scanning electron microscope (SEM) providing with energy dispersive spectrometer (EDS) unite. These studies revealed the presence of several valuable minerals like Euxenite and Fergusonite as well as; gives a clear comparative idea on the mineralogical and geochemical characteristics of the Nb-Ta oxides.