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In this study, the mobility of natural uranium in fractured granite was investigated by focusing on the roles of uranyl silicate minerals formed by long-term interactions with oxic groundwater. Uranium-bearing minerals observed in granite samples were identified as uranyl silicate minerals (i.e., uranophane, haiweeite, and soddyite) and this result was supported by uranium speciation calculation. The uranyl silicate minerals play important roles in understanding the mobility of uranium and the effects of water–rock interactions on long-term behavior of uranium in fractured granite systems.

Hydrometallurgical processing of micaceous bands concentrate for recovering U and Th using sulfuric acid agitation leaching was studied. This concentrate assays 4.1% ZrO2, 3.8% Nb2O5, 1.2% RE2O3, 2.8% ThO2, and 0.55% U3O8. The corresponding minerals of these elements include zircon, ferrocolumbite, fergusonite, uranothorite, autunite, and uranophane. About 96% of Th and 94% of U were dissolved under optimum leaching conditions: 30% H2SO4, 1/3 S/L ratio, 4 h leaching time, and 85°C leaching temperature. Di(2-ethylhexyl) hydrogen phosphate (HDEHP) in kerosene was used for U extraction with 90.9% efficiency and its separation from Th in the presence of 0.3 M EDTA solution. Th was then selectively precipitated from the raffinate solution as Th peroxide.

The present work deals with the detailed geology, mineralogy, geochemistry, and spectrometric prospection of the felsic volcanic rocks at the Eastern Desert, Egypt of the Arabian-Nubian Shield. Felsic volcanic rocks are an essential source for rare earth elements (REEs) and uranium occurrences in this area. They are compositionally uniform with tholeiitic to calc-alkaline affinities, peraluminous and belong to the series of rhyolite with high-K melt. They exhibit more enrichment in high field strength elements (HFSE, e.g. Zr, Ta, Nd, Th, and U) and large-ion lithophile elements (LILE, e.g. Pb and Rb) compared to the country rocks of the studied area, with REE ranging from 188.20 to 442.70 ppm and strong depletion in Ti, Sr, P with deep negative Eu oddities. The felsic volcanic rocks were mostly generated from the partial melting of quartz-amphibolite facies accreted during the Neoproterozoic. Positive oddities of Zr- U- Th for the felsic volcanic rocks determine the involvement of crustal materials. Felsic volcanic rocks are found in A-type suites of magma and represent highly fractionated rocks derived from rhyolitic magma, with insignificant interaction with continental crust in the low-pressure environment and during fractional crystallization. Felsic volcanic rocks have higher values of radioactivity in which eU range from 0.5 to 121 ppm and eTh from 1.0 to 415.10 ppm. The high values of eU and eTh can be ascribed to the mineralization of uranium and the presence of accessory minerals of radiogenic nature such as uranophane, uranothorite, zircon, and monazite. Uranophane is considered as the mineral with most enriched uranium contents in the studied felsic volcanic rocks in which (UO2 = 87.30 wt %). Also, they are enriched with REE-bearing accessory minerals comprising allanite, titanite, and apatite. The geological investigations of the felsic volcanic rocks in the studied areas are inappropriate to clear the feasible economic potentialities of rare earth elements and U occurrences; itemized and invaluable explorational work is as yet needed. Whilst, the environmental impact of mineralization, owing to U and Th and their radiogenic daughter products, is observed and must be elaborated minutely.

The present work deals with the mineralogy, geochemical behavior and uranium potentiality of the monzogranites of El Maghrbia area, which comprise G. El Maghrbia and G. El Eredyia and situated in the central Eastern Desert of Egypt. G. El-Erediya monzogranites represents a promising area for uranium mineralizations. These granites have shear zone filled with red and black silica veins containing many radioactive anomalies with visible yellow secondary uranium minerals. The shear zone is highly affected by different degrees of alterations such as silicification, kaolinitization, sassuritization and ferrugination. Monzogranites of El-Erediya area possess higher values of their radioactivity than in El Maghrbia monzogranites in which eU and eTh, reaches up to 792.3 and 66.81 ppm, whilst average content of eU and eTh in El Maghrabia granites are 3.86 and 8.55 ppm, respectively owing to the presence of radioactive minerals such as uraninite, uranothorite, uranophane, kasolite, betafite, zircon and monazite. Intensive geochemical analyses indicated that, the studied monzogranites are distinctly anomalous in U, where the average U is more than 620-fold the Upper Continental Crust (UCC), marked enrichment (> tenfold) of the elements Cd, Mo, Pb, Bi, Nb and W. The Th/U ratio decreases from 2.8, as a chondritic value, to 0.0023 for the studied granites, proposing extreme fractionation towards an extensive secondary migration-in of U. The Zr and Hf are depleted in the studied granites relative to the UCC, whereas Nb and Ta are strongly enriched. The content of Y is about sixfold enriched which reflects relative enhancement of the HREE during the alteration processes. Uranium correlates with Fe2O 3 T , suggesting a possible association between uranium and ferrugination. Thus, the occurrences of uranium are epigenetic by remobilization from the host rock to the sheared zones, probably through metasomatic process where U–Fe–Mg replaced the feldspars in an oxidized condition. The high levels of radioactivity in the rocks being studied it them a priority for discovery and expanding the potentiality of the highly mineralized localities.

G. El Sela is located in the Southern Eastern Desert of Egypt cropping as two parts, occupied by monzogranites that were categorized as biotite granite, muscovite granite and two mica granites. The northern part is more significant according its high concentrations of uranium that controlled by complicated structure regime; faulting, infrastructures and shearing are the most common structural criteria of this part. The Egyptian Nuclear Materials Authority (NMA) mined this part to produce the uranium ore. The previous mineralogical studies indicated that this granite was dominated by primary uranium minerals (pitchblende and coffinite) and secondary minerals belong to the autunite group (autunite, metautunite, phurcalite) in addition to uranophane. In the present work, petrographic and mineralogical studies are applied for the granites using the polarized and stereo microscopes and followed by electron microscope and XRD. The result of the microscopic examinations revealed the tectonic regime controlling the radioactivity and recognized the sodic autunite (meta-natroautunite) beside the pre-mentioned autunite group minerals completing the paragenetic sequrnce of these minerals. In this study, it is concluded that the sheared biotite granite is monzogranite originated during the episode of the continental plate collision (syncollision). The study finished to presence of two main types of the alteration corresponding to the two high levels of radioactivity (moderate and anomalous). The first is the thermal alteration (saussiritization, sericitization, kaolinization, silicification and hematization) and the second is the chemical transformation (oxidation, dehydration, ion substitutions and confusion) responsible for formation of the secondary uranium minerals. The temperature needed for the thermal alteration is sourced by the hydrothermal solutions, while the temperature needed for the uranium minerals transformation may be generated during the episode of the continental plate collision (syncollision). Paragenesis of these minerals indicates that they represent a series of uranyl phosphate minerals (autunite group) with paragenetic sequence starting by autunite (calcic uranyl phosphate) and ends by meta-natroautunite (sodic uranyl phosphate). An advanced process of dehydration accompanies the process of mineral transformation from autunite to meta-natroautunite leading to formation of the anhydrous uranyl mineral (phurcalite) formed by oxidation and dehydration of autunite. Meta-autunite is recorded as a transitional mineral composed of sodic-calcic uranyl phosphate. Uranophane is created by thermal confusion of autunite with the silica.

The Gabal El Sela and Gabal Qash Amir younger granites in the Arabian Nubian Shield (ANS) occurred within the Onib- Sol Hamed suture zone in the southern Eastern Desert of Egypt. In the study area, a pluton composed of biotite granites, muscovite granites and two mica granites is crosscut by altered dibase, microgranitic and bostonite dykes with a distinctive distribution of mineralization with high concentrations of rare metals. Silicification, hematitization, kaolinitization, episyenitization and sericitization are the main hydrothermal alteration processes in these younger granites. Gabal El Sela fractured younger granite shows highly alteration, uranium enrichment and a strong enrichment in some rare elements (such as; Zr = 2287 ppm, Y = 1123 ppm and Nb = 269 ppm) whereas, the bostonite dyke (such as; Zr = 1604 ppm, Y = 709 ppm and Nb = 292 ppm). Gabal Qash Amir muscovite granite shows a favorable enrichment in some rare elements (such as; Zr = 1898 ppm, Y = 181 ppm and Nb = 966 ppm) while, the bostonite dyke (such as; Zr = 1500 ppm, Y = 711 ppm and Nb = 286 ppm). Mineral characterization of the highly radioactive zones shows enrichment in autunite, uranophane, uranothorite, zircon, xenotime, monazite, fergusonite, samarskite and columbite. Field radiometric measurements of the studied El Sela fractured granite revealed that eU reaches up to 459.5 ppm, bostonite dyke eU reaches up to 58 ppm and altered basic dyke eU reaches up to 1625 ppm, while Qash Amir muscovite granite eU reaches up to 51 ppm and the bostonite dyke eU reaches up to 34 ppm. Geological, mineralogical, radiometrical and geochemical studies indicated that Gabal El Sela fractured younger granite is the most promising area characterized by strong enrichment in both uranium and some rare metals mineralization than Gabal Qash Amir muscovite granite.

International audience; Uranium (U) deposits can undergo oxidizing events, subsequent to which the U may be redistributed or precipitated under distinct mineralogical forms. Occurrences of U6+ minerals can be the result of either (i) in situ oxidation and alteration of previous U4+ minerals or (ii) direct precipitation from U6+-rich solutions. Samples from Imouraren, the largest U6+ore deposit known in the world, located in the Tim Mersoï Basin, Northern Niger, have been studied to determine the nature, distribution, and timing of occurrences of U and related minerals. The host rock is composed of sandstones and analcime-rich siliciclastic rocks of Jurassic age. The U ore is largely dominated by acicular hexavalent U minerals and by a very small amount of uraninite. A comprehensive geochemical model that describes the origin and geochemical setting of this style of economically important mineralization has been developed. The petrographic and mineralogical studies show evidence of in situ uraninite alteration into uranophane and metatyuyamunite, documented by textural relationships and chemical analyses using SEM and electron microprobe. The textural relationship between the U4+ and U6+ minerals is supported by the near-identical REE signatures of the primary uraninite and related secondary U minerals. Ion microprobe U-Pb dating (from 21 to ~ 1 Ma) confirms that primary uraninites were altered to U6+ minerals under supergene conditions during Cenozoic oxidation events in western Africa, in relation with the well-known stages of intense continental weathering that have affected western Africa from the early Cenozoic to recent times.

The NNW-SSE trending leucogranites in and around Mastipuram, Wanaparthi district, Telangana are intrusive into Peninsular Gneissic complex. The leucogranite is metaluminous to mildly peraluminous, alkali-feldspar granite with I-type signatures, probably formed from a fractionated melt involving crustal component. Magmatic and hydrothermal contributions are supported by wide range of U/Th ratios in mineralized samples, which also show Na-enrichment as compared to non-mineralized leucogranites. Average U and Th contents and U/Th ratio in mineralized leucogranite is 541ppm, 147 ppm and 2.85, respectively. Main ore mineral is uraninite and its altered form - gummite, while secondary uranium minerals such as schoepite, uranophane and haiweeite are also identified in leucogranite by XRD. Reconnoitory drilling of ten boreholes have confirmed sub-surface continuation of uranium mineralization with varying width of 1m to 31m at vertical depth of about 50m. Thus, the leucogranites bordering Gadwal schist belt around Mastipuram forms a very potential target.

Gabal Shendib alkaline ring complex forms high positive topographic rock units of concentric circularoutcrop. The igneous complex has a diameter of 12 km emplaced within the metavolcanics and tonalitegranodioritehost rocks. The complex consists of olivine gabbro, alkaline granite, alkaline syenite and remnants of the volcanic rocks represented by porphyritic trachyte, porphyritic rhyolite, rhyolite and tuffs. These alkaline rocks show a strong enrichment in some rare metal contents (Zr = 4527, Nb = 717, Y = 806 ppm) and rare earth elements (La = 553, Ce = 1581, Pr = 214, Nd = 1145, Sm = 299, Gd = 55, Dy= 85ppm). The highest Rb/Sr ratio and lower Ba/Rb ratio of the studied alkaline rocks of Gabal Shendib ring complex indicating a high degree of fractionation of the melt associated with mineralization.REE abundance patterns of the alkaline granite and alkaline syenite display M-type and W-type tetradeffect with strong Eu depletion in both whole rock samples. Fluid-melt interaction in the late stage offractional crystallization is suggested to be the most important factor controlling the formation of REEtetrad effects in these alkaline rocks. The most important REE-bearing minerals are zircon, xenotime,monazite, allanite and apatite. Other accessory minerals include columbite, uranophane, urnothorite andtitanite are identified.Field radiometric measurements and chemical analysis for uranium content of the alkaline granite and alkaline syenite revealed low uranium content. Radioactivity level reaches up to 13.70 ppm eU in alkalinegranite and 4.90 ppm eU in the alkaline syenite. Chemical analysis of uranium revealed that U contentreaches up to 35 ppm in the alkaline granite and 15 ppm in the alkaline syenite.

U-Pb isotope systems have been used to constrain the timing of formation, alteration, and oxidation of U minerals from the meta-granitic bedrock at Forsmark, eastern Sweden. Secondary ion mass spectrometry (SIMS) has been used to collect U-Pb data from uraninite. Discordant data suggest a ~1.8 Ga emplacement of uraninite-bearing pegmatites and an event of uraninite alteration at ~1.6 Ga. The latter age is contemporaneous with the Gothian orogeny in Scandinavia, which was associated with hydrothermal fluid circulation in the Fennoscandian Shield. Ca-uranyl silicates haiweeite and uranophane predominately formed 1.3–1.2 Ga, contemporaneous with the emplacement of the Satakunta complex of the Central Scandinavian Dolerite Group. A Palaeozoic group of Ca-U(VI)-silicates is also present, which indicates that the geochemical composition of geologic fluids was heterogeneous throughout the fracture network during this time. Low Pb concentrations in the U(VI) silicates of several samples are compatible with a recent (

Kaolinitization, ferrugination, silicification, and illitization hematitization are the main alteration types recorded in the Gabal (G.) El Sela area, South Eastern Desert, Egypt. These altration zones occur in successive manar as supergene events along faults plane causing mineral redistribution. Uranium mineralization observed in the northern part of Gabal El Sela is mainly controlled by complicated structure regime: faulting, infrastructures, and shearing. So, the northern part of Gabal El Sela area is considered as the most significant and U-fertile part in the studied area. Visible secondary uranium minerals (uranophane and autunite) have been identified and are found to be related mainly to kaolinitized and ferruginated altered samples. Also, pyrite and chalcopyrite can be recorded as reduced Fe bearing minerals in fewer amounts than in hematite and goethite minerals. Finally, the present work confirms that G. El Sela granite is considered as one of the most promising granite plutons in Egypt. The fertility parts are mostly related to the extent of the overlap between the magmatic uranium enrichment, hydrothermal reworking through open fracture system, and suitable reservoir for the leached mineral. The U mineralization may be the result of all these reactions between the granite and the successive fluids.

Long-term uranium mobility in tailings is an environmental management issue. The present study focuses on two U-enriched layers, surficial and buried 14.5 m, of the tailings pile of Cominak, Niger. The acidic and oxidizing conditions of the tailings pile combined with evapotranspiration cycles related to the Sahelian climate control U speciation. Uraninite, brannerite, and moluranite as well as uranophane are relict U phases. EXAFS spectroscopy, HR-XRD, and SEM/WDS highlight the major role of uranyl sulfate groups in uranium speciation. Uranyl phosphate neoformation in the buried layer (paleolayer) acts as an efficient trap for uranium.

The Picoto mining area is in the village of Vilar Seco (Viseu), central Portugal. Mineralization occurs mainly in quartz veins with meta-torbernite and uranophane and some U-bearing minerals, cutting a Variscan granite. Exploitation took place in two phases, between 1917 and 1953, and since the closure, the area has never been remediated. Water–rock interaction processes, including the mobility of potentially toxic elements through soil and water (surface and groundwater), were identified with the determination in situ of physicochemical parameters and selected anions and cations, by ICP-OES. The soils are contaminated with As (&gt, 44 mg/kg), Cu (&gt, 23 mg/kg), and U (&gt, 40 mg/kg) and cannot be used for agricultural or domestic purposes. The waters are generally weakly mineralized and have pH values ranging from acidic to neutral. However, some of them are contaminated with NO2 (up to 2.3 mg/L), Fe (up to 1849 mg/L), Mn (up to 777 mg/L), Cu (up to 5.4 µg/L), As (up to 14.7 µg/L), and U (up to 66.2 µg/L) and cannot be used for human consumption or agricultural activities. The soil and water contamination are mainly related to the old mine activities and the subsequent human activities that have developed in the area.

In this work, the probable sites of the radioactive mineralization in the younger granite of the Um Bogma area was mapped, prospected and detected by using geospatial technology. Our approach combined diverse data that have a close relationship with radioactive mineralization. These data are lithological, hydrothermal alteration minerals and airborne data. To achieve the aim of this work, the geospatial technology was used. Two techniques band ratio and Feature Oriented Principal Component Analysis (Crosta technique) were applied on ASTER satellite images to distinguish lithology and minerals indicative of hydrothermal alteration. Estimated weights were assigned to the lithology, alteration minerals and airborne data based on statistical methods. All these weighted data integrated to produce the predictive control models that related to mineralization using GIS applications. Three potential sites for radioactive mineralization were identified from the predictive control model. These potential sites were validated via fieldwork surveillance from these sites. Both of fieldwork and laboratory examinations confirm the association of these potential sites with the altered younger granite where uranophane and other minerals are recorded.

The main rock types exposed at Wadi Ras Abda area are subduction-related older granite intruded by fine-grained alkali feldspar granite (microgranite intrusions). These rock types are dissected by acidic dykes (rhyolite) and basic dykes (basalt and dolerite) with their associated pegmatites and quartz veins. Ras Abda microgranite is highly radioactive and this radioactivity is structurally related. The thorium, uranium, and rare metal mineralization are distinguished within the microgranite intrusions along fault zones that are trending N40° E with high dipping angle reaching to 86°. It shows radioactive measurements ranging from 500 to 9500 ppm and showing visible secondary uranium and thorium minerals in addition to the deposition of black rare metal minerals. Uranothorite, thorite, and secondary uranium minerals (uranophane) are the main radioactive minerals at Wadi Ras Abda area, in addition to the rare earth–bearing mineral (REE) fergusonite. Six events are affected in W. Ras Abda area. Each event begins with compression (CP) and then extensional (EXT) phase of deformation. These events were arranged chronologically basing on field relations from the oldest to the youngest as following: WNW-ESE (CP), NNE-SSW (EXT), E-W (CP), N-S (EXT), NE-SW (CP), NW-SE (EXT), NNE-SSW to N-S (CP), WNW-ESE to E-W (EXT), NW-SE to NNW-SSE (CP), ENE-WSW to NE-SW (EXT) and ENE-WSW (CP), and NNW-SSE (EXT). The WNW-ESE to E-W–directed tensile stress reactivated faults and induced new faults along which the mineralized fluids flow. It is recognized that the low-stress regions in the vicinity of faults and their associated tension joints, along contacts between microgranite and older granite, are favorable locations for alterations and Th-U and REE mineralization.

The shear zone of the El-Missikat area is considered one of the most important occurrences of uranium (U) mineralization in the Central Eastern Desert of Egypt. This shear zone is characterized by a tabular elongated zone of crushing and brecciation resulting from many parallel fractures or intense jointing, and presence of silicification and other alteration products together with the occasional presence of U mineralization. The concentrations of the natural radionuclides were measured by Sodium Iodide Detector NaI (Tl) in 87 granitic rocks and silica veins collected from the Central Eastern Desert. Measurement of radioactive elements suggests U present in granite of the El-Missikat pluton as well as in red, black and jasperoid silica veins. Radioactive mineralization was determined by scanning electron, binocular, and polarizing microscopies. The mineralizations are represented by syn-genetic U-leaching origin accompanying granitic rocks and post-magmatic association in red and black silica veins. The U-host mineralizations are mainly represented by radioactive minerals such as uranophane, kasolite, and U-bearing zircon.

Three new materials related to the phosphuranylite family were synthesized by using alkali chloride fluxes at 875 °C: CsNa3[(UO2)3O2(PO4)2] (1), Cs2Na4[(UO2)5O5(PO4)2] (2), and Rb6[(UO2)5O5(PO4)2] (3). CsNa3[(UO2)3O2(PO4)2] (1) crystallizes in the triclinic space group P1 with the lattice parameters, a = 6.9809(3) A, b = 9.3326(4) A, c = 12.9626(5) A, α = 71.5620(10)°, β = 78.9430(10)°, and γ = 68.0840(1)°; Cs2Na4[(UO2)5O5(PO4)2] (2) crystallizes in the triclinic space group P1 with the lattice parameters, a = 6.9890(3) A, b = 12.9652(6) A, c = 13.2086(6) A, α = 96.224(2)°, β = 101.433(2)°, and γ = 105.459(2)°; and Rb6(PO4)2[(UO2)5O5] crystallizes in the P21/m space group with the lattice parameters, a = 6.9255(3) A, b = 24.773(1) A, c = 7.07647(3) A, and β = 90.741(1)°. The sheets of 1 are based on the phosphuranylite topology, while the sheets of 2 and 3 contain sheets based on the U3O8 and uranophane topologies but differ in the orientation of the phosphate tetrahedra. The regions between the sheets ...

The layered uranyl silicate clay-like mineral, uranophane-α, Ca(UO2)2(SiO3OH)2·5H2O, was studied by first-principles calculations based on the density functional theory method. The structure, observed in nature in a wide variety of compounds having the uranophane sheet anion topology, is confirmed here for the first time by means of rigorous theoretical solid-state calculations. The computed lattice parameters, bond lengths and bond angles were in very good agreement with the experimental ones, and the calculated X-ray powder trace accurately reproduced its experimental counterpart. The mechanical properties of uranophane-α, for which there are no experimental data for terms of comparison, were determined, and the satisfaction of the mechanical stability Born conditions of the structure was demonstrated by calculations of the elasticity tensor. The Raman spectrum was computed by the density functional perturbation theory and compared with the experimental spectrum. The vibrational properties of this mineral were well characterized, showing a good performance in all of the studied spectral range. Theoretical methods allowed assignment of the Raman bands to vibrations localized in different fragments within the crystal unit cell. Finally, the possibility of incorporation of strontium inside the uranophane structure was studied. The computed structure, X-ray powder trace and Raman spectrum of Sr-exchanged uranophane were very close to those of the ordinary Ca-uranophane.

Information-based parameters of structural complexity for two polymorphs of Ca[(UO 2 ) 2 (SiO 3 OH) 2 ] · 5H 2 O, uranophane and uranophane-β, were calculated in order to assess the impact of the structural complexity on their stability and formation. Calculations proved that uranophane-β is far more complex ( I G,total = 691.90 bits/cell) than uranophane ( I G,total = 345.95 bits/cell), which indirectly suggests that uranophane may form as a metastable phase during crystallization process. This suggestion is further supported by the lower density of uranophane (3.834 g/cm 3 ) compared to that of uranophane-β (3.983 g/cm 3 ). The hypothesis of a metastable character of uranophane is in agreement with Goldsmith’s simplexity principle and the Ostwald–Volmer rule and is well supported by the frequency of occurrences of both dimorphic minerals in Nature.

Heterogeneous equilibria in the system Ca(HSiUO6)2 · 5H2O(c)–aqueous solution were studied over broad ranges of pH, ionic strength, and ionic composition of the solution, and the pH range of stability of Ca uranyl silicate is determined. Hydrolysis products of Ca uranyl silicate are identified, and their solubility is determined. The equilibrium constant of the dissolution reaction and the standard Gibbs function of formation of Ca(HSiUO6)2 · 5H2O are calculated from experimental data, and solubility curves of uranophane and equilibrium speciation diagrams for U(VI), Si(IV), and Ca(II) in coexisting aqueous solutions and solid phases are calculated.

The southern part of the Eastern Desert of Egypt—about 30 km southwest of Abu-Ramad city—is mainly covered by ophiolitic rocks (Sul Hamed), island arc assemblage, younger granites (muscovite granites of Qash Amer and two mica granites of El Sela), and various acidic and basic dikes. Field, petrological, and geochemical studies indicate that the El Sela shear zone has been subject to hydrothermal and supergene alteration such as kaolinization, albitization, sericitization, and hematitization. It is invaded by quartz ENE–WSW veins associated with hydrothermal alteration accompanied by radioactive mineralization. The investigated younger granitic rocks had very low contents of compatible elements, such as Cr, Ni, and Co; and high contents of incompatible elements, such as Zr, and large ion lithophiles, such as Sr, especially in the El Sela shear zone. Major oxide and trace element analyses revealed calc-alkaline affinity and peraluminous character. These highly differentiated granitic rocks’ lower Zr/Hf and higher Y/Ho than the normal ratio are consistent with hydrothermal alteration. Most samples had rare earth element (REE)-patterns with an M-type tetrad effect in the first and fourth segments and a W-type tetrad in the third segment. The average ∑REE in the studied granites was lower than the world granite average; the ratio of light to heavy REEs greater. The main radioactive, uranium-bearing, and uraniferous Fe and Mn minerals are uranothorite, autunite, uranophane and autunite as compounds, kasolite, columbite, xenotime, uranophane-bearing zircon and jarosite, silver-bearing pyrite, hematite, and autunite-bearing pyrolusite.

The Younger Granites of Yahmid-Um Adawi area, located in the southeastern part of Sinai Peninsula, comprise two coeval Late Neoproterozoic post-collisional alkaline (hypersolvous alkali-feldspar granites; 608–580 Ma) and calc-alkaline (transsolvous monzo- and syenogranites; 635–590 Ma) suites. The calc-alkaline suite granitoids are magnesian and peraluminous to metaluminous, whereas the alkaline ones are magnesian to ferroan alkaline to slightly metaluminous. Both granitoid suites exhibit many of the typical geochemical features of A-type granites such as enrichment in Nb (>20 ppm), Zr (>250 ppm), Zn (>100 ppm) and Ce (>100 ppm) and high 10000*Ga/Al2O3 ratios (>2.6) and Zr + Nb + Y + Ce (>350 ppm). Accessory mineral saturation thermometers demonstrated former crystallization of apatite at high temperatures prior to zircon and monazite separation from the magma for both granitoid suites. The mild zircon saturation temperatures of the studied Younger Granites (around 800 °C) imply low-temperature crustal fusion and incomplete melting of the largely refractory zircon. The two Younger Granite suites were semi-synchronously evolved during the post-collisional stage of the Arabian-Nubian Shield subsequent to the collision between the juvenile shield crust and the older pre-Neoproterozoic continental blocks of west Gondwana. Their parental magmas has been generated by melting of crustal source rocks with minor involvement from mantle, which might participated chiefly as a source of heat necessary for fusion of the crustal precursor. Extensive in-situ gamma-ray spectrometry revealed anomalously high radioactivity of some Younger Granite exposures along Wadi Um Adawi (eU; 388–746 ppm and eTh; 1857–2527 ppm) and pegmatitic pockets pertaining to the calc-alkaline suite (equivalent U and Th; 212–252 ppm and 750–1757 ppm, respectively). The radioactivity of the syngenetic pegmatites arises from the primary radioactive minerals uranothorite and thorite together with the U- and/or Th-bearing minerals zircon, columbite, samarskite and monazite. The anomalously high radioactivity of some Younger Granite exposures in Wadi Um Adawi stem from their appreciable enclosure of the epigenetic uranium minerals metatorbenite and uranophane.

In this work, several individual grains of uranium minerals—uraninite with high content of Ca, Ca-rich boltwoodite, growths of uranophane with β-uranophane, and weeksite—from different uranium deposits were studied by a scanning nuclear microprobe. Particle-induced X-ray emission technique provided by the microprobe (µ-PIXE) was carried out to obtain a concentration and 2D distribution of elements in these minerals. In addition, energy dispersive X-ray spectrometry (SEM-EDS) provided by a scanning electron microscope was used. The types of minerals were determined by X-ray diffraction methods. Results of this study improved the understanding of trace elemental composition of the uranium minerals depending on their origin. Obtained signatures could be linked then to the sample provenance. Such data are important for nuclear forensics to identify the ore types and even specific ore bodies, when only small samples may be available for analysis. In this study, the µ-PIXE technique was used for obtaining the 2D distribution of trace elements that are not commonly measured by SEM-EDS at the relevant concentrations. The detected levels and precisions of elements determination by µ-PIXE were also defined. Using µ-PIXE, several micro mineral inclusions such as phosphate with high level of V and Si were identified. The age of the uranium minerals was estimated due to a significant content of radiogenic Pb that provides an additional parameter for determination of the main attributive characteristics of the minerals. This work also showed that due to its high elemental sensitivity the nuclear microprobe can be a new analytical tool for creating a nuclear forensic database from the known uranium deposits and a subsequent analysis of the intercepted illicit materials.

Sonrai basin, located along the southwestern margin of Bundelkhand Granite-Gneiss Complex (BGC) is known for its base metal and phosphorite mineralization. Uranium mineralization of appreciable grade and thickness was reported in Pisnari block in the northern part of this basin during sub-surface exploration activity in 1976-97. This was in the form of uranium-bitumin association within fractures in the carbonate-terrigenous sediments of Gorakalan shale, Rohini carbonate and Bandai sandstone of Sonrai Formation of Bijawar Group. Similar mineralization was also noted within the lower chloritic shale member of Solda Formation of the same Group. During subsequent drilling activity at a later phase (2005-09), uranium rich zones within Rohini carbonate and chloritic shale members were corroborated by the interception of mineralized bands in two boreholes drilled near Pisnari. Petrographic study of radioactive core samples reveal that uranium mineralization is closely associated with globular carbonaceous matter and sulphides along the fractures. Uranium is either adsorbed in carbonaceous matter or occurs as ultrafine inclusions of coffinite within carbonaceous matter. An additional phase of secondary uranium mineral (uranophane) is also noted in one of the boreholes. The uranium minerals, in association with sulphides, fill up moderately dipping fractures (approximately 15o towards North) which are oblique to the core axis of the inclined borehole and thus, the mineralization is characterized as hydrothermal fracture-controlled vein type mineralisation. C-HN- S analysis of carbonaceous matter occurring in close association with the uranium minerals reveal heterogeneity in composition with respect to carbon and sulfur. The present paper aims at discussing the geological, petrological and radiometric aspects of this mineralization, so as to enhance the understanding of the same.