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The paper presents results of modeling the chemical interactions of Quaternary meteoric waters with siltstones of the upper part of the Vendian Padun Formation of the Mezen Syneclise, Arkhangelsk region, Russia. Equilibrium and equilibrium-kinetic approaches were applied. It is shown that under conditions of intensive water exchange and low temperature, due to low rates of interaction of minerals with water, the redox buffer of rock-forming minerals at this stage of the process makes a subordinate contribution to the dissolution of uranium. Therefore, for a sufficiently long time, the main agent of mobilization of uranium in rocks is oxygen dissolved in water. [ABSTRACT FROM AUTHOR]

This study presents a complete characterization of kenoplumbomicrolite, (Pb,□)2Ta2O6[□,(OH),O], occurring in an amazonite pegmatite from Ploskaya Mountain, Western Keivy Massif, Kola Peninsula, Murmanskaja Oblast, Northern Region, Russia. Kenoplumbomicrolite occurs in yellowish brown octahedral, cuboctahedral and massive crystals, up to 20 cm, has a white streak, a greasy lustre and is translucent. The Mohs hardness is ~6. Attempts to measure density (7.310–7.832 g/cm3) were affected by the ubiquitous presence of uraninite inclusions. Reflectance values were measured in air and immersed in oil. Kenoplumbocrolite is optically isotropic. The empirical formula is (Pb1.30□0.30Ca0.29Na0.08U0.03)Σ2.00(Ta0.82Nb0.62Si0.23Sn4+0.15Ti0.07Fe3+0.10Al0.01)Σ2.00O6[□0.52(OH)0.25O0.23]Σ1.00 (from the crystal used for the structural study) and (Pb1.33□0.66Mn0.01)Σ2.00(Ta0.87Nb0.72Sn4+0.18Fe3+0.11W0.08Ti0.04)Σ2.00O6[□0.80(OH)0.10O0.10]Σ1.00 (average including additional fragments). The mineral is cubic, space group Fd $\overline 3 $ m. The unit-cell parameters refined from powder X-ray diffraction data are a = 10.575(2) Å and V = 1182.6(8) Å3, which are in accord with those obtained previously from a single crystal of a = 10.571(1) Å, V = 1181.3(2) Å3 and Z = 8. The mineral description and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2015-007a). [ABSTRACT FROM AUTHOR]

The article discusses the study which aims to establish the uranium- (U) thorium- (Th) lead (Pb) chemical age of grains of accessory monazite and uraninite from the basement's granites in Yaman Peninsula. Using an electron microprobe, the grains of monazite and uraninite have been explored and identified wherein element distribution in grains was checked on the basis of measurement of the intensity and background peaks. The researchers have calculated that the bimineral isochrome age of monazite and uraninite grains is 259.6 (00B1 2.3 Ma by utilizing the point determination of U, Th, and Pb.

The article presents a study on the composition and age structure of granitoid plutons found at the megabasin of Western Siberia, Russia. It states that granitoids are considered as the most perspective rocks used for researches on hydrocarbon raw materials in sedimentary basins. It mentions the materials used in the study which include granite plutons with oval form, isotopic and chemical dating of the granosyenite samples, and isometric rounded grains of uraninite. It says that the chemical dating presents the total lead content in the mineral which means that uraninite still has lead content. Moreover, it adds that the age structure and temperature of the granitoid plutons are viewed to be shown by the difference between the chemical age and absolute age of the uraninite.