Nine samples of carbonate-free sodalite-group minerals, including those with abnormally high contents of polysulfide groups, fluoride anion and carbon dioxide molecules as well as synthetic fluoraluminate sodalite-type compound Na₈(Si₇Al₅O₂₄)(AlF₆)^3–·5H₂O, have been studied by means of electron microprobe analyses, infrared and Raman spectroscopy; the CO₂ content was determined using the selective sorption of gaseous ignition products. This article describes a semi-quantitative method for estimating the content of carbon dioxide molecules in these minerals, based on IR spectroscopy data. The data obtained demonstrate the existence of a sulfide sodalite-group mineral with the idealized formula Na₇(Si₆Al₆O₂₄)(S₃⁻)·H₂O, which differs significantly from the formula Na₆Ca₂(Si₆Al₆O₂₄)S^2–₂ accepted for lazurite. According to single-crystal X-ray structural analysis, in the F-rich sodalite-group mineral from the Eifel paleovolcanic region, Germany with the idealized formula Na₇(Si₆Al₆O₂₄)F⁻·nH₂O fluorine occurs as an isolated F⁻ anion, unlike synthetic F-rich sodalite-type compounds.

Chlormagaluminite is the only Cl-dominated hydrotalcite-supergroup mineral species with M²⁺:M³⁺ = 2:1. The holotype sample of chlormagaluminite from the Kapaevskaya volcanic pipe (Irkutsk Oblast, Siberia, Russia) has been chemically and structurally characterized. The average chemical composition of the mineral is (electron microprobe, OH content is calculated by stoichiometry and H₂O from the crystal-structure data, wt. %): MgO 33.85, FeO 1.09, Al₂O₃ 22.07, Cl 14.72, H₂O_tot 30.96, Cl=O −3.39, total 99.30. The empirical formula based on Mg + Al + Fe = 6 atoms per formula unit (apfu) is [Mg_3.91Fe²⁺_0.07Al_2.02(OH)₁₂]Cl_2.02(H₂O)_2.0(2). The crystal structure has been solved from single-crystal X-ray diffraction data in the space group P6₃/mcm, a = 5.268(3), c = 15.297(8) Å and V = 367.6(4) ų. The refinement converged to R₁ = 0.083 on the basis of 152 unique reflections with I > 2σ(I) collected at room conditions. The powder pattern contains standard reflections of a 2H polytype and two additional reflections [(010), d₀₁₀ = 4.574 Å; (110), d₁₁₀ = 2.647 Å] indicative of Mg and Al ordering according to the $\sqrt{3}\times \sqrt{3}$ superstructure. The structure is based upon brucite-type octahedral layers with an ordered distribution of Mg and Al over octahedral sites. The Cl⁻ anions and H₂O molecules reside in the interlayer, providing a three-dimensional integrity of the structure.

Dritsite, ideally Li₂Al₄(OH)₁₂Cl₂·3H₂O, is a new hydrotalcite supergroup mineral formed as a result of diagenesis in the halite−carnallite rock of the Verkhnekamskoe salt deposit, Perm Krai, Russia. Dritsite forms single lamellar or tabular hexagonal crystals up to 0.25 mm across. The mineral is transparent and colourless, with perfect cleavage on {001}. The chemical composition of dritsite (wt. %; by combination of electron microprobe and ICP−MS; H₂O calculated by structure refinement) is: Li₂O 6.6, Al₂O₃ 45.42, SiO₂ 0.11, Cl 14.33, SO₃ 0.21, H₂O_calc. 34.86, O = Cl − 3.24, total 98.29. The empirical formula based on Li + Al + Si = 6 apfu (atom per formula unit) is Li_1.99Al_4.00Si_0.01[(OH)_12.19Cl_1.82(SO₄)_0.01]_Σ14.02·2.60(H₂O). The Raman spectroscopic data indicate the presence of O–H bonding in the mineral, whereas CO₃^2– groups are absent. The crystal structure has been refined in the space group P6₃/mcm, a = 5.0960(3), c = 15.3578(13) Å, and V = 345.4(5) ų, to R₁ = 0.088 using single-crystal data. The strongest lines of the powder X-ray diffraction pattern (d, Å (I, %) (hkl)) are: 7.68 (100) (002), 4.422 (61) (010), 3.832 (99) (004, 012), 2.561 (30) (006), 2.283 (25) (113), and 1.445 (26) (032). Dritsite was found as 2H polytype, which is isotypic with synthetic material and shows strong similarity to chlormagalumite-2H. The mineral is named in honour of the Russian crystallographer and mineralogist Prof. Victor Anatol`evich Drits.

Understanding the speciation of technogenic uranium in natural systems is crucial for estimating U migration and bioavailability and for developing remediation strategies for contaminated territories. Reference EXAFS data of model laboratory-prepared uranium compounds (`standards') are necessary to analyze U-contaminated samples from nuclear legacy sites. To minimize errors associated with measurements on different synchrotrons, it is important not only to compare data obtained on environmentally contaminated samples with the literature but also with `standards' collected at the same beamline. Before recording the EXAFS spectra, all reference compounds were thoroughly characterized by Raman spectroscopy and powder X-ray diffraction. The U(VI) local molecular environments in the reference compounds, i.e. uranyl oxyhydroxides, phosphates, carbonates and uranates, were examined using XAFS. Based on the EXAFS fitting results obtained, including the nature of the bonding, interatomic distances and coordination numbers, parameters that are typical for a particular U compound were differentiated. Using data for `standards', U speciation in the sample of radioactively contaminated soil was determined to be a mixture of U oxyhydroxide and carbonate phases.

Samples of Chernobyl fuel debris, including massive corium and “lava” were collected inside the Chernobyl “Sarcophagus” or “Shelter” in 1990, transported to Leningrad (St. Petersburg) and stored under laboratory conditions for many years. In 2011 aged samples were visually re-examined and it was confirmed that most of them remained intact, although some evidence of self-destruction and chemical alteration were clearly observed. Selected samples of corium and “lava” were affected by static leaching at temperatures of 25, 90 and 150 °C in distilled water. A normalized Pu mass loss (NL_Pu) from corium samples after 140 days was noted to be 0.5 g/m² at 25 °C and 1.1 g/m² at 90 °C. For “lava” samples NL_Pu was 2.2–2.3 g/m² at 90 °C for 140 days. The formation of secondary uranyl phases on the surface of corium and “lava” samples altered at 150 °C was confirmed. The results obtained are considered as an important basis for the simulation of fuel debris aging at Fukushima Daiichi nuclear power plant (NPP).

Three generations of tourmaline have been identified in propylite in the Vetka porphyry copper-molybdenum deposit of the Chukchi Peninsula of Russia. Tourmaline-I is characterized by its Fe_tot/(Fe_tot + Mg) value, which ranges from 0.33 to 0.49. Tourmaline-II, which crystallizes at a lower temperature, overgrowing tourmaline-I or occurring as isolated crystals, is distinguished by a higher Fe_tot/(Fe_tot + Mg), which varies from 0.46 to 0.72. The Fe_tot/(Fe_tot + Mg) ratio in tourmaline-III, which overgrows tourmaline-II is lower (0.35–0.49), and is identical to that of the first tourmaline generation. This is probably caused by the beginning of sulfide deposition. Tourmalines in the deposit characterized by complex isomorphic substitutions can be attributed to the intermediate members of the dravite—“hydroxy-uvite”-“oxy-uvite” and schorl-“hydroxy-feruvite”-“oxy-feruvite” series. Tourmaline starts to crystallize at temperatures above 340°C. The fluid responsible for the tourmaline deposition was magmatic, with a significant admixture of meteoric water (δ¹⁸O_{H 2}O = −0.85 to −0.75‰). The high Fe³⁺/Fe_tot ratio (0.50) indicates high oxygen activity when the tourmaline precipitated. It has been established that the isomorphic substitution Fe_tot → Al is typomorphic of tourmalines from porphyry copper deposits worldwide.