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Thermodynamic numerical simulations were carried out to determine the principal simple and complex migration species of Ca, Mg, Na, K, Al, B, Mn, Mo, Sr, and U with Cl–, OH–, SO4−2, HCO3−, and CO32− in waters at the Lomonosov diamond deposit and to estimate the saturation indexes with respect to kaolinite, Na- and Mg-montmorillonite, Mg- and Na-saponite, muscovite and paragonite, biotite, phlogopite, chromite, pyrite, plagioclase (anorthite, labradorite, and andesine), olivine (forsterite and fayalite), diopside, pyrope, gypsum, anhydrite, barite, magnesite, calcite, dolomite, talc, chrysotile, chlorite, goethite, quartz, microcline, and albite. The waters are proved not to be saturated with respect to the primary (hydrothermal) minerals. The saturation of certain water samples with uranophane suggests that this mineral is of secondary genesis. The ascent of highly mineralized deep waters shall result in the dissolution of minerals whose concentrations are near the saturation ones. To maintain the ecological standards of the discharged waters, they should be diluted and/or purified by adsorbing dissolved U on a reducing reactive barrier.

The Gabal Nasb El Atshan Upper Carboniferous-Lower Permian altered trachytes include uranium up to 3165 ppm. The paleostress and resolved shear stress analyses of the deformation systems in Gabal Nasb El Atshan area indicate that the trachyte was subjected to WNW-ESE to E-W tensile shear stress directed extensional regimes. The low-stress regions in the vicinity of extensional faults and their associated joints were favorable locations for fluid flow and the consequence alteration and U-mineralization. This occurred more extensively along the contacts between the sills of trachyte and the Hammamat sedimentary rocks; where the latter acted as a physical barrier for the alteration fluids migration outward. Alteration styles include albitization , aegirinization, arfvedsonization, chloritization and ferruginisation. The albitization is the most common sodic metasomatism , giving sanidine from Or 98.8Ab0.7 to Or62.3Ab37.6, anorthoclase from Or51.4Ab48.0 to Or12.2Ab87.6 and albite from Or 11.0Ab89.0 to Or0.8Ab99.2 . Aegirine and arfvedsonite formed due to decreasing sodium activity in the metasomatic fluids. Sodic metasomatism may be the source of uranium-enrichment, taking place during the late magmatic to deuteric processes. This was followed by a retrograde alteration of chloritization between 175 and 42 °C toward precipitation of Fe-oxides and alteration of primary uranium. Surficial low-temperature alteration remobilized and redistributed the produced uranylhydroxides and ferruginisation caused the reduction and adsorption of U forming betafite, uranophane, soddyite, umohoite, uranotile and uranopilite.

A cation exchange chromatography method employing sulfonated polysterene cation resin (DOWEX AG50-X8) was developed in order to separate rare-earth elements (REEs) from uranium-rich materials. The chemical separation scheme is designed to reduce matrix effects and consequently yield enhanced ionization efficiencies for concentration determinations of REEs without significant fractionation using solution mode-inductively coupled plasma mass spectrometry (ICP-MS) analysis. The method was applied to determine REE abundances in four uraninite (ideally UO2) samples and their associated U(VI) alteration minerals. In three of the samples analyzed, the concentration of REEs for primary uraninite are higher than those for their corresponding secondary uranium alteration phases. The results for U(VI) alteration minerals of two samples indicate enrichment of the light REEs (LREEs) over the heavy REEs (HREEs). This differential mobilization is attributed to differences in the mineralogical composition of the U(VI) alteration. There is a lack of fractionation of the LREEs in the uraninite alteration rind that is composed of U(VI) minerals containing Ca2+ as the interlayer cation (uranophane and bequerelite); contrarily, U(VI) alteration minerals containing K+ and Pb2+ as interlayer cations (fourmarierite, dumontite) indicate fractionation (enrichment) of the LREEs. Our results have implications for nuclear forensic analyses since a comparison is reported between the REE abundances for the CUP-2 (processed uranium ore) certified reference material and previously determined values for uranium ore concentrate (UOC) produced from the same U deposit (Blind River/Elliott Lake, Canada). UOCs represent the most common form of interdicted nuclear material and consequently is material frequently targeted for forensic analysis. The comparison reveals similar chondrite normalized REE signatures but variable absolute abundances. Based on the results reported here, the latter may be attributed to the differing REE abundances between primary ore and associated alteration phases, and/or is related to varying fabrication processes adopted during production of UOC.

The Hammamat sediments at Wadi Belih area are represented by greywacke and siltstones. The greywackes are immature and are fine to coarse grained and composed of quartz, feldspar and rock fragments. The siltstones consist of quartz, feldspar and hematite. The younger granites (The Gattar granites) are composed mainly of quartz and feldspars as essential minerals and biotite, hornblende, zircon, and apatite as accessory minerals. Some secondary minerals as epidote, chlorite and sericite are found. The radioactive minerals are identified by using the Quanta FEG-250 ESEM instrument which is an environmental Scanning Electron Microscope (ESEM) attached by Energy Dispersive X-ray(EDX) in the national central research (NCR). The younger granites and Hammamat rocks at Wadi Belih area contain primary uranium mineral as Coffinite, secondary minerals as Uranophane, Kasolite, Schroeckingerite and uranium bearing minerals like Columbite.

The young granites of El Maghrabiya area located at the Central Eastern Desert, the southwestern part, are intensively altered along faults, fractures, and shear zones. Microscopically, the studied granites are classified as syenogranite and the altered portion exhibits features of ferrugination and episyenitization. This granite belongs to the high silica and low calcium, iron, and magnesium granites reflecting their origin from highly fractionated potassium-rich crustal material. El Maghrabiya syenogranites are generally uraniferous especially the altered portion that is characterized by high radioactivity. The hydrothermal activity is responsible for the formation of the anomalous zone characterized by extensive episyenitization and ferrugination processes. The ferruginated syenogranite has higher concentrations of uranium and thorium than the other altered granites (episyenitized). The present study revealed that zircon, fluorite, fluorapatite, and iron oxides are the most predominant U-bearing minerals in addition to uranophane that recorded in the ferruginated variety. The studied syenogranites characterized by two thorium ranges where the fresh granite exhibits the low range (22–45 ppm) and the altered granite characterized by the higher range (68–185 ppm) indicating that there are two pulses of the magma generating El Maghrabiya young granites. Uranium and thorium of the first generation are mostly attributed to the accessory minerals and related to the magmatic processes while the second generation is characterized by low Th/U ratio and high uranium content that is enriched by the hydrothermal solutions.

15 pags., 9 figs., 7 tabs., The crystal structure, elastic properties and the Raman spectrum of the layered calcium uranyl silicate pentahydrate mineral uranophane-β, Ca(UO2)2Si2O6(OH)2·5H2O, are studied by means of first-principles solid-state methods and compared with the corresponding information for the α polymorph. The availability of the energy optimized full crystal structure of uranophane-β, including the positions of the hydrogen atoms, made possible the computation of its elastic properties and the Raman spectrum by using the theoretical methodology. An extended set of relevant mechanical data is reported. Uranophane-β is shown to be a weak and ductile mineral and, consequenty, is mechanically very different from the α polymorph which is a hard and brittle material. Uranophane-β exhibits the important negative Poisson's ratio (NPR) and negative linear compressibility (NLC) phenomena. The experimental Raman spectrum of uranophane-β obtained from a natural mineral sample from pegmatite Perus, São Paulo, Brazil, is compared with the spectrum determined theoretically. Since both spectra are in very good agreement, the theoretical methods are employed to assign the Raman spectrum. Three weak bands of the experimental spectrum of this mineral, located at the wavenumbers 2302, 2128 and 2042 cm−1, are identified as combination bands. The Raman spectrum of uranophane-β is also compared with that of the α polymorph. While they are rather similar, a detailed analysis reveals a significant number of differences. Finally, the relative thermodynamic stability of the α and β polymorphs is evaluated. The α polymorph is more stable than the β polymorph at zero pressure and temperature by −12.0 kJ mol−1, The supercomputer time provided by the CTI-CSIC center is greatly acknowledged. This work has been carried out in the context of a CSIC–CIEMAT collaboration agreement: “Caracterización experimental y teórica de fases secundarias y óxidos de uranio formados en condiciones de almacenamiento de combustible nuclear”. JP acknowledge the support of the Ministry of Education, Youth and Sports National Sustainability Program I of the Czech Republic through the project no. LO1603. JS was supported by the Ministry of Culture of the Czech Republic (long-term project DKRVO 2019-2023/1.II.a; National Museum, 00023272).

Ras Abda Area is located in the north part of the Eastern desert, and is characterized by a rugged topography and high relief. The main exposed rock units in the area comprise older granites, younger gabbros and granites as well as several types of post granite dykes (rhyolite, basic and microgranite dykes). Radiometric measurements indicated that the microgranite samples are characterized by anomalous concentrations of the radioelements which mean that the rocks originated from radioelements-bearing magma and may be subjected to epigenetic processes of leachability and migration of uranium. The stream sediments samples show low levels of radioactivity where eU ranges from 4.0 to 7.0 ppm with an average of 5.3 ppm, and eTh ranges from 6.0 to 18.0 ppm with an average of 10.65 ppm. The eTh/eU ratio ranges from 1.2 to 3.6 where the samples distal from the microgranite dykes are characterized by the highest eTh/eU ratio (3.6) while those close to the dykes have the lower eTh/eU ratios. Generally, the average eTh/eU ratio (∼2.08) is lower than the world ratio (3.5) implying that uranium probably enriched from an adjacent source may be the microgranite dykes. The calculated factors of equilibrium (P and D) indicated disequilibrium state for both rocks types (microgranite and stream sediments) and referred to incomplete U-decay series. Mineralogical studies revealed that the heavy minerals could be classified into: a) radioactive minerals comprising uranophane, kasolite, sklodowskite, thorite and uranothorite, and b) radioelements-bearing minerals comprising columbite, fergusonite, samarskite, pyrochlore, allanite, monazite, zircon and fluorite. The heavy minerals are mostly concentrated upstream rather than downstream; meandering portions of the stream may act as natural traps for the heavy minerals. Keywords: Ras abda, North eastern desert, Egypt, Microgranite dyke, Radioactivity, Mineralogy

Understanding the factors that govern aqueous solubility of uranyl minerals is important for predicting uranium mobility in groundwater and for designing effective remediation strategies. The uranyl-containing minerals metaschoepite [UO3∙(2H2O)] and uranophane [Ca(UO2)2(SiO3OH)2·5H2O] were synthesized and evaluated in batch solubility experiments conducted in the presence of common groundwater ions: calcium, bicarbonate/carbonate, and dissolved silica. Solid-phase characterization revealed the expected structural and thermogravimetric properties of metaschoepite and uranophane. Metaschoepite solubility in carbonate-free water followed a u-shaped pH dependency with minimum solubility near pH 8.5; uranium concentrations at pH ≳ 8.5 were approximately equivalent to the reference value for safe drinking water established by the EPA (30 μg/L). With increasing bicarbonate/carbonate concentration (1 mM – 50 mM) the solubility of metaschoepite increased, presumably due to the formation of uranyl-carbonate complexes. However, the experimental concentrations of uranium were lower than concentrations predicted from accepted complexation constants. For uranophane, equilibrium uranium concentrations were < 75 μg/L at typical groundwater concentrations of calcium and dissolved silica (pH > 7). The diversity of uranyl minerals that possibly form in the presence of common groundwater species: Ca-Mg-Na-K-Si-bicarbonate/carbonate-sulfate-chloride, has not been fully explored with respect to understanding potential mineral transformations and impacts on uranium solubility and mobility.

Raman spectroscopy studies have been performed on one hand to identify different materials related to spent nuclear fuel (SNF), and on the other hand to study the behavior of SNF at different storage conditions. Specifically, the expected oxidation of the SNF matrix under dry storage conditions and the formation of secondary phases (SP), as a result of corrosion of SNF in a deep geological repository, have been studied. In order to perform these experiments, two protocols based on the Raman spectroscopy technique have been developed. The results show U4O9/U3O7 and U3O8 as oxidation products of UO2 powder at high temperatures in air, and the secondary phase formation (rutherfordine, UO2(CO3), soddyite, (UO2)2SiO4•2H2O, uranophane alpha Ca(UO2)2(SiO3OH)2•5H2O and kasolite, PbUO2SiO4•H2O), due to uraninite corrosion under the conditions of Sierra Albarrana (Spain).

Uranium deposits form in a variety of settings. They are partially controlled by the secular evolution of Earth processes, including deposits in extension-related settings such as the intra-cratonic Rio Grande rift. Plio-Quaternary volcanism, mineral deposits, and hydrothermal spots occur along the Chihuahua Central Graben. The age of the Sierra de Gomez U-deposit is 1.8 Ma (based on LA-MC-ICP-MS dating on a uranophane monocrystal), which is contemporaneous with the late mineralization event of the Pena Blanca U-deposit, as well as Rio Grande Rift (RGR)-type deposits in Chihuahua and intraplate volcanism. Studies of fluid inclusions in fluorite and late calcite indicate the presence of hydrocarbons and CH4-rich brine. Homogenization temperatures range from 87 to 112 °C, and the mean composition (2.0 mol NaCl and 0.3 mol CaCl with CH4) is comparable to mineralizing brines in MVT deposits and carbonated hydrocarbon reservoirs. Evolution of C and O stable isotopic values for the calcite cement in the Sierra de Gomez Limestone-hosted U deposit illustrates that two separate calcite precipitation events occurred: (1) travertine filling karst structures in the presence of meteoric water and (2) U mineralization during deep hydrothermal fluid circulation that included interactions with a heat source and basement leaching. In a regional context, a metallogenic model suggests that the Chihuahua Trough area is deep enough to generate fluid migration by hydrothermal and/or compaction processes through RGR extensional faults until a favorable trapping horizon is reached. This causes uranium precipitation because water/rock interaction processes generate a local redox barrier.

Eastern Brazilian Pegmatite Province includes many topaz-bearing pegmatitic bodies. Residual melts from the Fe–K-rich alkaline Medina granite (ca. 500 Ma) formed the Serrinha pegmatite—a system of branched thin pegmatite veins hosted by pink facies of the parent granite. The colourless topaz from Serrinha pegmatite contains both mineral and fluid inclusions. Microcline (513, 476, 456 cm−1), albite (507, 479, 457 cm−1), topaz (926, 858, 267, 239 cm−1), quartz (463 cm−1), rutile (610, 444 cm−1), wolframite (884 cm−1) and uranophane (968, 788 cm−1) represent solid inclusions formed by fluid-induced processes from the pneumatolytic (∼600–400 °C) to hydrothermal (

The northern part of Um Ara alkali feldspar microgranite has subjected to extensive post-magmaticmetasomatic reworking resulting in development of amazonitized and albitized zones, reflecting K- and Nametasomatism leading to gross enrichment in U and Th towards the more evolved phases (e.g., albitizedzones). Spectrometric survey data indicate that eU in Dokhan volcanics has the range of 2 to 42 ppm withan average value of 10 ppm and in monzogranites. It varies from 3 to 13 ppm with an average of 7 ppmwhile in alkali feldspar microgranites eU contents vary from 3 to 282 ppm with an average value of 30 ppm.The (eTh) contents in Dokhan volcanics ranges from 5-51 ppm with an average 18 ppm, in monzogranitestheir content was in the range of 11 to 47 ppm with an average value of 27 ppm where it ranges from 14to 83 ppm with an average 46 ppm in alkali feldspar granite. The enhanced uranium content in alteredzones was attributed to disseminated and fracture filling uranophane, autonite, in addition to other U andTh bearing minerals (such as columbite, zircon, monazite, xenotime and fluorite). Gamma-radiation doserate and annual effective dose equivalents in mSv/y, Radium equivalent activity, external (Hex) and internalhazard index (Hin) and gamma activity index (I) for all investigated samples were calculated to assess thepotential radiation hazard for people living in dwellings made of the studied granites. Alkali feldspar graniteactivities would suggest that caution must be taken when using granites as building materials because theyhave radioactivity above the proposed acceptable level.

Syenogranitic dykes in the north of Egypt’s Eastern Desert are of geological and economic interest because of the presence of magmatic and supergene enrichment of radioactive mineralization. Zircon crystal morphology within the syenogranitic dykes allows precise definition of sub-alkaline series granites and crystallized at mean temperature of about 637 °C. The growth pattern of the zircons suggest magmatic and hydrothermal origins of radioactive mineralization. Hydrothermal processes are responsible for the formation of significant zircon overgrowth; high U-zircon margins might have occurred contemporaneously with the emplacement of syenogranitic dykes which show anomalous uranium (eU) and thorium (eTh) contents of up to 1386 and 7330 ppm, respectively. Zircon chemistry revealed a relative increase of Hf consistent with decreasing Zr content, suggesting the replacement of Zr by Hf during hydrothermal activity. Visible uranium mineralization is present and recognized by the presence of uranophane and autunite.

The studied area at Wadi Nugrus, Southeastern Desert, Egypt, is located between lat. 24°41'00'' and 24°41'35''N and long. 34°36'47'' and 34°37'09''E. The rock types are represented by layered metagabbros, biotite schists, gneisses, granodiorites, and Muscovite granites. The muscovite granite of Wadi Nugrus, is small exposure in size (~5.0 km2), emplaced along NW-SE trend, with about 0.5 - 4.5 Km in length and 100 - 250 m in width and intruding the biotite schists. The studied muscovite granite is composed mainly of plagioclases, potash feldspars, quartz, biotite and muscovite. The recorded minerals assemblage can be classified into secondary U-minerals (uranophane and meta-autunite), U-bearing minerals (uranothorite and columbite) and accessory minerals (zircon, flourite, allanite, zinnwaldite and hematite). The U/eU is more unity where, the measured chemical uranium is higher than the measured equivalent uranium in the most analyzed samples especially in trenches, which reflect disequilibrium state. The activity concentrations range from 251.72 to 1096.2 Bq·kg-1 for 232Th, from 494 to 2593.5 Bq·kg-1 for 226Ra, and from 1314.6 to 1846.7 Bq·kg-1 for 40K. The obtained radiological data show that the average internal and external hazard indices are 9.11 and 5.78, respectively which are more than unity and highly exceeding the permissible limits (International Commission on Radiation Protection, ICRP). The internal and external hazards are mainly due to 226Ra nuclei while the absorbed dose rate (nGy/h) is related to 232Th nuclei. The contributions of the three nuclei in the total absorbed dose rates and internal and external hazardous, for 226Ra, it contributes by 72% in Hin, 57% in Hex and 55% of DR, for 232Th it contributes by 24% in Hin, 37% in Hex and 36.9% of DR, while for 40K it contributes by 4.1% in Hin, 6.4% in Hex and 8.1% of DR.

The mineralogical studies on Black mica raw material revealed the presence of notable high radioactive minerals such as uranium minerals (Soddyite, Uranophane, Uranothorite, and Ishikawaite), niobium - tantalum minerals (Columbite and Plumbopyrochlore), and rare earth elements minerals (Allanite, Xenotime, and monazite). From mineralogical and chemical studies make it possible to determine optimal processing conditions, the preferred lixiviate option, and the required costs. Black mica sample was found to assay 1680 mg/Kg U, 5000 mg/Kg REEs, and 50,750 mg/Kg Nb while Ta not exceeds 5000 mg/Kg. Through applying sulfuric acid agitation leaching, 92% of uranium was dissolved under optimum leaching conditions of: 8% concentration of H2SO4 acid, 1/4 solid/liquid ratio at room temperature for 4 h reaction time, while RE2O3, Nb2O5 and Ta2O5 remained in the unattacked residue. A phosphate mixture was used for rapid dissolution of refractory minerals, REEs, Nb and Ta minerals, after fusion, which give 97.8%, 99%, and 97%, respectively, leaching efficiencies. Ion exchange, solvent extraction and precipitation techniques were used for separating and recovery of U, REEs, Nb, and Ta species from their leach liquor.

The southern Central Zone (sCZ) of the Neoproterozoic to early Palaeozoic Damara orogenic belt hosts significant uranium deposits in Namibia. Rossing South-West, a leucogranite-hosted uranium deposit in the sCZ is partitioned into two sections; north-easterly and south-westerly sections with the latter (termed mining licence 120, i.e. ML120) forming the locus of this investigation. The deposit lies within the vicinity and to the west of the Welwitschia lineament which served as a conduit for mineralized fluids along with the Rossing and Husab deposits. Mineralogy and major and trace element geochemistry of the uraniferous leucogranites in ML120 suggest they are S-type granites derived from a sedimentary source as evidenced by the presence of igneous phases of garnet and cordierite together. Microscope and electron microprobe results from 133 powdered, drill core and hand samples prove that the deposits host similar primary uranium mineralization (chiefly uraninite which mainly exist as independent uranium minerals) and similar secondary U mineralization. At Rossing-SW U minerals include uraninite, coffinite, pitchblende, betafite, uranophane, betauranophane, carnotite, gummite and might partially exist as Th isomorphs. Mineralization at all locales is associated with post-tectonic D and E-type sheeted leucogranites containing quartz, alkali-feldspar and variable amounts of plagioclase producing rocks of variable compositions from tonalite to alkali-feldspar granite. Total reserves calculated at a cut-off grade of 100 ppm were reported as 171 Mt of ore at 376 ppm for Rossing and 205 Mt of ore at 497 ppm for Husab (probable). The Rossing-SW orebody is open-ended however total inferred resources stand at 304.4 Mt of ore at 235 ppm while measured resources stand at 8830t ore at circa 231 ppm. A comparison of the geological parameters (uranium mineralogy, leucogranite petrology and geochemistry) suggests similar ore composition. Consequently, ore from Rossing-SW's ML120 area could be processed at existing metallurgical plants (such as at Rossing or Husab) with a probable increase in U3O8 yield.

223Ra,224Ra,226Ra, and228Ra isotopes have been measured in groundwaters from depths ranging 50–900m in fractured crystalline bedrock (Forsmark, Sweden) to understand the reason for elevated (up to 150μg/L) aqueous uranium (Uaq) at 400–650m depth. Ra isotope data is interpreted alongside previously reported222Rn,234U, and238U data, as well as PHREEQC geochemical modelling and uranium mineralogy. A novel, [223Ra/226Ra]GW-based approach (where brackets and “GW” subscript refer to expression of an activity ratio measured from groundwater) to groundwater residence time estimation shows that elevated [Uaq] is most common in Holocene-age groundwaters of marine origin. Although these groundwaters are geochemically reducing, the [223Ra/228Ra]corr(where “corr” subscript refers to a correction applied to compare [223Ra/228Ra]GWto the more commonly reported [226Ra/228Ra]GW) suggest that they interact with U-rich pegmatites containing Proterozoic- and Palaeozoic-age Ca-U(VI)-silicate minerals, which are undersaturated in the present groundwaters. Local aqueous U(VI) can be stabilized in Ca2UO2CO30complexes at pe-values as low as −4.5 but is susceptible to reduction after a modest decrease in pe-value, alkalinity, or Ca concentration. The [223Ra/228Ra]corrand [224Ra/228Ra]GWalso suggest that U(VI)aqprecipitates as UO2+Xat the interface between marine and non-marine groundwaters. From these data, local [Uaq] is proposed to be governed by on-going water-rock interaction involving old U(VI)-minerals.

This work determines the capacity of uranophane, one of the long-term uranyl secondary solid phases formed on the spent nuclear fuel (SNF), to retain radionuclides (cesium and strontium) released during the dissolution of the SNF. Sorption was fast in both cases, and uranophane had a high sorption capacity for both radionuclides (maximum sorption capacities of 1.53·10-5¿mol¿m-2 for cesium and 3.45·10-3¿mol¿m-2 for strontium). The high sorption capacity of uranophane highlights the importance of the formation of uranyl silicates as secondary phases during the SNF dissolution, especially in retaining the release of radionuclides not retarded by other mechanisms such as precipitation.

A mina de urânio de Picoto localiza-se nas imediações de Vilar Seco (Viseu, Centro de Portugal). A mineralização ocorre principalmente num sistema de filões de quartzo leitoso e fumado, brechóide, que preenche fraturas e falhas com direção N37º-45ºE e N50º-70ºE e, mais raramente, N5º-20ºE, cortando um granito varisco de grão médio a grosseiro, porfiroide, biotítico>moscovítico. Este sistema de filões é mineralizado com metatorbernite e uranófano, mas também contém outros minerais portadores de urânio, como a moscovite, clorite e hidróxidos de Fe, de Fe e Ti e de Mn. Nas áreas adjacentes às fraturas e falhas, o granito foi afetado por processos de alteração hidrotermal, sofrendo um intenso metasomatismo alcalino, lixiviação de quartzo e importantes transformações na mineralogia primária, sendo designado de episienito. No episienito, a microclina apresenta-se turva e fortemente enrubescida devido à presença de pequenas inclusões de óxidos e hidróxidos de Fe ao longo de microfraturas e poros. O granito também se encontra meteorizado, com evidências de caulinização do feldspato e oxidação da biotite. Em ambas as rochas alteradas ocorre, de forma disseminada em microfraturas e espaços intergranulares, metatorbernite, de idêntica composição, e hidróxidos de Fe. A metatorbernite dos filões de quartzo é mais rica em arsénio (atingindo 0,41% de As2O5) do que a metatorbernite do episenito e do granito meteorizado., The Picoto uranium mine area is located close to Vilar Seco village (Viseu, central Portugal). The mineralization occurs mainly in a brecciated, milky and smoky quartz vein system, filling N37º-45ºE and rarely, N5º-20ºE trending fractures and faults, which intersect a Variscan medium- to coarse-grained porphyritic biotite>muscovite granite. The quartz vein system is mineralized with metatorbernite and uranophane, and some other U-bearing minerals, such as muscovite, chlorite and Fe-, Ti and Fe- and Mn-hydroxides. Adjacent to those trending fractures and faults, there are reddish altered rocks, commonly known as “episyenites”, which resulted from hydrothermal alteration processes, involving alkali metasomatism, quartz dissolution and transformation of primary minerals. In the episyenites, the microcline is very turbid and heavily stained due to the presence of very fine-grained dispersed Fe-oxides and hydroxides. The granite is also meteoric weathered, showing strong evidences of feldspar kaolinization and biotite oxidation. In both altered rocks, there are disseminated metatorbernite, of similar chemical composition, and Fe-hydroxides filling along microfractures and spaces between grain boundaries. The metatorbernite from quartz veins is richer in arsenic (reaching 0,41 wt % de As₂O₅) than that from the episyenite and meteoric weathered granite., info:eu-repo/semantics/publishedVersion

Um Ara area is located in the extreme south Eastern Desert of Egypt between 581400mE-584900mE and 2503000mN-2504600mN. The area comprises distinct tectono-stratigraphic units beginning with the oldest as follows: Dokhan volcanic and post-collision granitoids (monzogranite, and alkali feldspar granite), and associated with dykes and quartz veins. The granite affected by deuteric K-metasomatism (microclinization) followed by Na-metasomatism (albitization) causing zonation in this part of the pluton. The high radioactivity in the anomalous sites is structurally controlled (strong shearing, fracturing and jointing). The intensity of mineralization is especially significant along joint sets striking NNW-SSE, NNESSW and NE-SW trending. The spacing among these joints ranges from few mm up to about 5 cm. locally, the joints are filled with kaolinite and other alteration products including hematite and Mnoxides. Geochemically, Um Ara granites trenches and core samples show a relative enrichment in K2O compositions due to plagioclase destruction and formation of muscovite/sericitization. Um Ara granites trenches and core samples have variable total REEs contents 117.41 to 308.28 and 256.51 to 397.22 ppm respectively. ΣLREEs in trenches and core samples range from 108.47 to 298.41ppm and from 236.84 to 384.78 ppm respectively, whereas ΣHREEs range from 5.48 to 14.01 ppm and from 12.44 to 19.67 ppm respectively. The lowest concentration of total REEs in core samples is at 100m depth, while the highest values at 145m depth. Um Ara granites trenches, U contents vary from 154 to 506 ppm with an average of 245.7 ppm, and Th contents vary from 47 to 415 ppm with an average of 165.4 ppm. Core samples granite, U contents vary from 128 to 349 ppm with an average of 237.3 ppm, and Th contents vary from 45 to 146 ppm with an average 107.4 ppm. Visible secondary uranium mineralization is represented mainly by uranophane and β-uranophane. Uranium is also contained within a range of U-bearing accessory minerals, mainly fluorite, monazite, xenotime, allanite and zircon. The secondary processes played a main role in uranium enrichment (uranium added to these granitic sites post-magmatically). Um Ara altered granites trenches and core samples rocks are an abnormal radiation and have an extension. So, these anomalies are suitable to be a place for uranium extraction. The result is the continuous of its mining work besides leachability experiments.

The present study deals with the mineralogical and radioactive characteristics of the pegmatitic rocks at Gabal El-Urf area, Central Eastern Desert of Egypt.The zoned pegmatites of El-Urf area are composed of three enriched mineral zones; extremely milky quartz core, intermediate mica zone and feldspars wall zone.The identified separated heavy minerals in the studied pegmatite can be grouped into three mineral groups; the primary minerals (pyrite, molybdenite, rutile, magnetite, thorianite, zircon, columbite and garnet), the secondary minerals (uranophane, kasolite, uranothorite, samarskite, uranopolycrase, dravite, ilmenorutile, allanite and titanite.) and the gangue minerals (lanarkite, barite, hematite, ilmenite, goethite, apatite, monazite and kamitugaite).The studied zoned pegmatites hosting or acting as a source for uranium and rare metals (Zr, Y, Nb and Th) mineralizations. Multistage deformation, magmatic and hydrothermal processes accompanied by events of uranium mineralization with the associated rare metals mineralizations in different episodes affected Gabal El-Urf zoned pegmatites.The rare metals can be originated through magmatic and hydrothermal fluids under the restrictive sets of conditions that commonly prevail in these zoned pegmatites. The magmatic and hydrothermal processes enriched with rare metals mineralization accompanied by event of an intensive tectonic structure affected Gabal El-Urf pegmatites.

The Thelon basin, Nunavut, shares many similarities with the uranium-producing Athabasca basin, Saskatchewan; however, the uranium deposits associated with the Thelon basin are still poorly understood. The Kiggavik project area (AREVA Resources Canada) is located near the northeastern terminus of the Thelon basin and comprises multiple uranium deposits hosted exclusively in basement rocks. The Bong deposit is hosted dominantly by Neoarchean metagraywacke of the Woodburn Lake group. A five-phase metallogenetic model is proposed for the Bong deposit, with three stages of uraninite identified. The premineralization phase is characterized by host-rock silicification. Mineralization is separated into three main stages. Stage 1 uraninite (U1; ca. 1500 Ma) is preserved in highly fractured and altered disseminated grains that are overgrown by later stages of uraninite. Stage 2 uraninite (U2; ca. 1100 Ma) forms veinlets parallel to D 1 foliation and coats and fills fractures in organic matter nodules and blebs. Stage 2 uraninite is associated with pervasive illite that formed from ~190°C fluids ( δ 18 O: −6.4‰, δ 2 H: −97‰), which remobilized much of Stage 1 uraninite and completely overprinted Stage 1 alteration. At ~1000 Ma an oxidizing fluid deposited uraninite along redox fronts (U3) while altering and remobilizing Stage 1 and 2 uraninite. Post-uranium-oxide minerals include drusy quartz, calcite, and illite accompanied by uranyl phases (e.g., uranophane, Ca-U).

Development of unconventional shale gas wells can generate significant quantities of drilling waste, including trace metal-rich black shale from the lateral portion of the drillhole. We carried out sequential extractions on 15 samples of dry-drilled cuttings and core material from the gas-producing Middle Devonian Marcellus Shale and surrounding units to identify the host phases and evaluate the mobility of selected trace elements during cuttings disposal. Maximum whole rock concentrations of uranium (U), arsenic (As), and barium (Ba) were 47, 90, and 3333 mg kg−1, respectively. Sequential chemical extractions suggest that although silicate minerals are the primary host for U, as much as 20% can be present in carbonate minerals. Up to 74% of the Ba in shale was extracted from exchangeable sites in the shale, while As is primarily associated with organic matter and sulfide minerals that could be mobilized by oxidation. For comparison, U and As concentrations were also measured in 43 produced water samples returned from Marcellus Shale gas wells. Low U concentrations in produced water ( Geochemical modeling to determine mobility under surface storage and disposal conditions indicates that oxidation and/or dissolution of U-bearing minerals in drill cuttings would likely be followed by immobilization of U in secondary minerals such as schoepite, uranophane, and soddyite, or uraninite as conditions become more reducing. Oxidative dissolution of arsenic containing sulfides could release soluble As in arsenate form under oxic acidic conditions. The degree to which the As is subsequently immobilized depends on the redox conditions along the landfill flow path. The results suggest that proper management of drill cuttings can minimize mobilization of these metals by monitoring and controlling Eh, pH and dissolved constituents in landfill leachates.

Uraninite is a mineral considered as an analogue of the spent fuel, and the study of its alteration products has been used to predict the secondary phases produced during the fuel storage under specific environmental conditions. In this work, we study by Raman spectroscopy the alteration by weathering of the primary uraninite from the uranium deposit of Sierra Albarrana. The identification of the different secondary phases is based on the analysis of the symmetrical stretching vibration of the uranyl group (UO 2 2+ ), which allows the identification of individual uranyl phases and can be used as a fingerprint. Additionally, we show in this work a new approach to perform a semi-quantitative analysis of these uranium minerals by means of Raman spectroscopy. From this analysis we found the next sequence of alteration products: rutherfordine in contact with the uraninite core, then a mixture of uranyl silicates: soddyite, uranophane alpha and kasolite. Soddyite prevails in the inner part while uranophane alpha predominates in the outer part of the sample, and kasolite appears intermittently (1.0–3.3 mm; 4.6–7.1 mm and 8.8–10 mm).

Five lamprophyre dikes (L1-L5) intruded Abu Rusheid rocks (cataclastics and monzogranite) in the South Eastern Desert of Egypt along shear zones with NNW-SSE and E-W. The two sets of dikes differ in age, mineralization, and geochemical aspect. The NNW-SSE trending dikes (L1 and L2) are polymineralized and dislocate the E-W (L3, L4, and L5) trending dikes. These dikes underwent multistage of hydrothermal processes (ferrugination, fluoritization, kaolinitization, and calcification). They are characterized by common box works (physical trap) filled by incoming mineralization, and their feldspars and micas are relatively altered to clay minerals (chemical trap). From the mineralogical point of view, the cataclastic rocks are rich in base metals (pyrite, sphalerite, molybdenite, chalcopyrite, and galena), radioactive minerals (thorite, uranophane, kasolite, uranothorite), and accessories phases (zircon, xenotime, cassiterite, molybdenite, copper, columbite, and fluorite). L1 and L2 lamprophyre dikes contain U minerals (uranophane, kasolite, autunite, and torbernite), Mn-franklinite, woodruffite, xenotime, fluorite, silver, copper, and scheelite. L3 contains Zn and U minerals, whereas L4 and L5 contain Zn minerals only. The source magma producing lamprophyre dikes (L1 to L4) are peralkaline to alkaline, whereas L5 lamprophyres are mainly calc-alkaline in character; they were generated from the mantle and had formed in a post-collision tectonic setting with extensive Ti-rich metasomatism. The average ΣREE content in (L1 and L2) lamprophyres is 8006 ppm. REE patterns display clear concave upward pattern of W-type tetrad effect in the REE pattern accompanied by enrichment of the HREE over the LREE and marked negative Eu anomaly due to secondary mobilization of REEs.

Wadi Murrah area is located in the extreme south Eastern Desert of Egypt. The area comprises four distinct tectono-stratigraphic units beginning with the oldest as follows: ophiolitic assemblage (dismembered ophiolitic rocks and ophiolitic melange), arc assemblage (metavolcanics, metagabbros, and older granites), post-collision granitoids (monzogranite, syenogranite, and alkali feldspar granite), and associated with dykes and quartz veins. The identified minerals in the samples taken from the anomalous sites of syenogranite and alkali feldspar granite in the northern part of the study area are represented by uranophane, autonite, meta-autonite, uranothorit, columbite, zircon, fluorite, monazite, xenotime, sphene, allanite, and apatite. The anomalous samples have U and Th average contents for syenogranites and alkali feldspar granites 82 and 104.4 ppm and 209 and 115.2 ppm, respectively. The high radioactivity in the anomalous sites is controlled lithologically and structurally. The secondary processes played a main role in uranium enrichment (uranium added to these granitic sites post-magmatically).

International audience; This study investigates the impact of incipient weathering on uranium (U) migration at the surface of granitic waste rock piles from former U mines in Limousin (France) operated half a century ago. We used a multi-scale mineralogical and geochemical approach to evaluate the impact of incipient weathering on uranium mobility in a chaotic waste rock pile. The surficial part of five former mines located in the “La Crouzille” and “La Creuse” mining districts was investigated. Four groups of samples were defined based on field observations and mineralogy, granites, lamprophyres, hydrothermally altered rocks and weathering products. Petrology, mineralogy and geochemistry investigations show the importance of mineralogical and geochemical transformations during incipient weathering over a few decades. The Chemical Index of Alteration (CIA) is successfully used to assess the weathering state of samples in the waste rock pile chaotic deposit. The mean CIA value is around 60 for unweathered/incipiently weathered granites whereas highly weathered samples have CIA around 70. This means that no significant major element loss occurs in the granitic rocks suffering incipient weathering. Various micron-size secondary U minerals consist in a large diversity of oxidized uranyl minerals (uranophane, uranyl sulfate, curite, autunite and other uranyl phosphates), with dominant uranyl phosphates, indicating local U mobility in the waste rock pile. Autunites micromorphology indicates different degrees of weathering of the samples in which it crystallizes. U is primarily concentrated in the clay fraction (< 2 μm), associated with secondary minerals from granite alteration (clay minerals such as smectite and vermiculite, Fe-oxides and phosphate minerals) and, to a limited extent, relict primary minerals. These weathering products contribute to U(VI) stabilization under oxidizing conditions.

The granite dike swarms intruding the older granitiod and occasionally the younger gabbros were emplaced througha shear zone extending in NE-SW direction. These dikes are composed mainly from alkali feldspar granites. They are finegrained, hard and compact vary in color from pink, red, reddish brown and occasionally bloody red. It is affected by varyingdegrees of alterations and subjected to deformation processes. Mineral segregations and pegmatite pockets are encounteredalong deformed and altered zones. Alkali feldspars mainly perthites and microcline, quartz, little sodic plagioclaseand biotite represent the main rock forming minerals. These dikes possess high contents of radioelements especiallythorium. The eTh contents range from 63.9 ppm to 2523 ppm with an average 465.8 ppm where the eU content range from25ppm to 497.9 ppm with 106.3 ppm average. The mineral segregations give the highest level of eU and eTh contents reach upto 7331 ppm and 1386 ppm respectively. Secondary uranium minerals (uranophane and curite), thorium minerals (thorite) andU- and Th-bearing minerals (Zircon, allanite, columbite, samarskite, xenotime, monazite, kasolite and titanite) are identified.Other non radioactive minerals such as magnetite, goetite, hematite, cronstedtite, pyrite, fluorite, garnet are also identified.Also, chemical analyses (XRF) revealed presence of high concentration of U, Zr, Y, Nb, Ba, Zn, Rb and Sr in addition to presenceof V, Pb, Ni and Cr. Au and Pt are also present

Korea has suffered from high U concentrations in some groundwater, especially in Daejeon near the central Ogcheon metamorphic belt. However, clear explanation has not been yet reported for the uranium sources in groundwater. This study is focused on identifying the potential uraniferous host rocks and finding the exact U-minerals serving as uranium sources in groundwater near Daejeon, Korea. For this work, we performed an in situ gamma ray spectrometer survey and a laboratory microscopic study with electron micro-probe analysis. The measurements for radioactive element content did not show any prominent K- and Th-anomaly spots, but they did result in several observations of considerable U-anomalies in pegmatite and hydrothermally altered granite, in which uraninite, coffinite and uranophane were found by electron micro-probe analysis. The occurrences of U-minerals are the first such discovery except in the low-grade U deposits of the Ogcheon metamorphic belt in Korea. All observed U-minerals were intimately associated with hydrothermal alteration. The remarkably low Th/U ratios in the studied uraniferous rocks also suggest that the U enrichment was genetically related to a post-magmatic hydrothermal process. However, many of the uraniferous parts were controlled by a reducing environment and occurred near the border between graphite-rich mica-schist and Jurassic leucocratic granite. The findings on these uraniferous rocks can be used in elucidating the source of highly enriched U groundwater in granite aquifers as well as in understanding the occurrence of igneous U-minerals, which has not been previously reported in Korea.

An economically important rare-metal mineralization is recorded in the cataclastic rocks at Wadi AbuRusheid area, South Eastern Desert of Egypt.Radiometric measurements of the main varieties of cataclastic rocks (protomylonites, mylonites,ultramylonites) show that their equivalent thorium (eTh) content is 7560, 8660 and 6210 ppm, whereas theequivalent uranium (eU) is 2544, 4170 and 790 ppm respectively.Microscopic examination, X-ray diffraction (XRD) and grain counting techniques revealed that thorite,zircon and columbite are the predominant radioactive minerals in all rock varieties , together with minoramounts of xenotime, cassiterite and sulphides. Beside these minerals, uranophane, kasolite and metaautuniteoccur as inclusions in other minerals.Physical upgrading of these minerals was carried out using gravitative separation technique. Applyingthe proposed flowsheet, it is possible to attain a good concentrate for these minerals with an acceptablerecovery. It is recommended to subject the final concentrates to hydrometallurgical treatments to extractthe important metals.

Khour Abalea in Abu Rusheid area is located at the midst part of the cataclastic rocks having U-shapedIt was formed as a result of deep strike-slip faults, some forming shear zone in some trends. Two forms ofpegmatites have been distinguished (pockets and veins) occurring within the cataclastic rocks as hostedrocks. Petrographically, they consist of quartz, orthoclase, microcline and micas.The identified minerals in the studied pegmatites can be grouped into primary uranium minerals(uraninite), secondary uranium minerals (kasolite, uranophane and meta-autunite), thorium minerals(thorite and uranothorite), the niobium-tantalum minerals (columbite, ferro-columbite, samarskite, euxeniteand fergusonite), the accessories (zircon, monazite, cassiterite, pyrite and fluorite) and mica (muscovite,phlogopite and fluor-phlogopite) as well as the opaques (hematite and goethite).Geochemically, the studied pegmatite (S-type) are calc–alkaline and peraluminous in nature. It is highlyfractionated possibly due to hydrothermal alterations. The REEs display clear tetrad effect of M-typeaccompanied with relative enrichment of the HREE over the LREE and marked negative Eu anomaly(Eu/Eu* =0.03 to 0.36). The calculated tetrad effect in the pegmatite demonstrates clear tendency towardsthe ratios of the common isovalents such as Zr/Hf, Nb/Ta and Y/Ho. However, the tetrad effect seems notto be mutual with the content of Na2O and Rb/Sr. The absence of coherence between tetrad effect and sodaor potassic contents may indicate insignificant role of the Na- or K-metasomatism in developing the tetradeffect.Detailed spectrometric survey of the study pegmatite revealed their enrichment of eU (49-306 ppm)and eTh (76-634 ppm) and the potential anomalous radioactivity is attributed to both magmatic andhydrothermal processes.

The metamorphosed sandstones exposures occur in two locations in Wadi Sikait. The exposed rocks in this area are ophiolitic melange, metamorphosed sandstones, porphrytic granites invaded by post-granite dykes (lamprophyres) and quartz-fluorite veins. The uranium contents measured radiometrically range from 3 to 41.97 ppm, with an average of 12 ppm, while the chemically measured are in the range from 20 to 100 ppm and averaging 50.83 ppm. High uranium contents are mainly attributed to the presence of secondary uranium minerals (uranophane and autonite), accessory minerals (monazite, zircon, allanite and xenotime) and U-bearing minerals (muscovite, biotite, chlorite, iron oxides and clays). P- and D-factors indicate disequilibrium in U-decay due to addition of uranium in these rocks. Since radioactive secular equilibrium of the young age deposits have not yet reached, therefore, the activity ratios (AR) of 230Th/234U in the studied rocks is very small and ranges from 0.43 to 1.3. Radon exhalation rates of the studied rocks were also measured using ‘‘Sealed Can technique” and indicated the presence of subsurface and surface uranium anomaly which confirms the previous results. Key words: Metamorphosed sandstones, uranium, minerals, Wadi Sikait.