The polytypic structure of Pd 8 T 3 ( T = As, Sb) compounds was revealed using the graph method. The topology of the layers and the regular sequence of their alternation are analyzed. The ordering of antimony and arsenic atoms by the positions at the nodes of layer-networks and the positional disorder in the sequence of alternating layers, which lead to the formation of different structural polytypes, are considered.

A mineral with the composition Pd(Bi0.53Sb0.47), intermediate between sobolevskite, ideally PdBi, and sudburyite, PdSb, from the Chineiskii Deposit (Transbaikal region, Russia), was studied by the SEM and XRD methods. Its crystal structure was solved and refined (R = 3.02

The results of a comprehensive detailed study of the vein structure, mineral zoning of veins, and mineral typomorphism of the Shakhtama deposit obtained on the basis of new samples from poorly studied horizons are given. The results obtained show that the Mo resources of the deposit are far from being exhausted, and the typomorphic features of ore minerals indicate that base metal mineralization associated with Au (Ag), also continues to a depth, along with Mo. The presence of rare Sr mineral, svanbergite, in the Shakhtamа deposit and the typomorphic properties of ore minerals testify in favor of the near-surface origin of the exposed mineralization. The succession of mineral formation has been established. Based on the study of ore and metasomatic zonality, fluid inclusions and isotopic data, as well as the composition of structural impurities in molybdenite, conclusions were made of the formation conditions of ore mineralization in a porphyry ore-forming system.

The polytypic structures of Pd8T3 (T = As, Sb) compounds was revealed using the graph method. The topology of the layers and the pattern in the sequence of their alternation are analyzed. The ordering of antimony and arsenic atoms by positions at the nodes of layer-networks and the positional disorder in the sequence of alternating layers, which lead to the formation of different structural polytypes, are considered.

The influence of structure, mineral and chemical composition of weatheringWeathering forms on the cultural heritage monuments have been studied by optical microscopy, petrographic analysis and electron microscopy. The objects of the study were architectural, memorial, museum monuments, built and decorated with natural (limestoneLimestones, dolomite, mica, etc.), or artificial (glassGlass, ceramicsCeramics and cement) materials. GypsumGypsum, oxides and hydroxides of iron, less often manganeseManganese oxides as well as sodium sulfates and halite are the main minerals of the surface formations on the architectural objects. Among the sulfates, we also found minerals of the jarositeJarosite group. They form either disseminated phenocrysts in dolomitic limestonesLimestones and sandstones in association with gypsumGypsum and goethite or interlayers in the clays enriched by organic matterOrganic matter. In urban conditions, formations such as streaks, spots and crusts on the architectural objects containing mortars and cement materials differ in the micro-layered structure, zoning of mineral composition and morphologyMorphology. The resistance of materials to biogenic weatheringWeathering was evaluated. The surfaces of the glazed tiles are the most stable to biogenic erosion.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23060065

AbstractThe synthetic analogue of mineral stillwaterite, Pd8As3, was synthesised and its crystal structure was solved to R1 = 0.0341 based on single crystal X-ray diffraction data. Pd8As3 is trigonal and the space group is P$\bar{3}$. The unit-cell parameters are a = 7.4261(4), c = 10.3097(9) Å and V = 492.38(7) Å3 with Z = 3. The structure builds up by layers of Pd and As atoms. Pd-nets and As-nets are parallel to (110) and stack along the c axis direction. The stacking sequence is ABCDEEDCBA. The relation between structures of minerals with the common formula Pd8T3 (T = As or/and Sb) are discussed. They are formed by nets of pnictogen and palladium atoms. The common feature of the structures is 36 topology of pnictogen nets. The differences are stacking sequences and topology of the palladium nets.

High-temperature transformation of β-PtBi2, a synthetic analogue of insizwaite, was studied under oxidizing conditions (on air). The behavior of the sample upon heating up to 660°C and cooling was studied by differential thermal analysis (DTA) and high-temperature X-ray powder diffraction. It was shown that polymorphic transitions of β-PtBi2 into high-temperature γ- and δ-polymorphs do not occur under thermal treatment in the oxidizing conditions (on air). The DTA curve shows two exothermic peaks at 318 and 620°C. The total weight change in the temperature range studied is +10.5

The article presents investigation of polymorphic transformations of the PtBi2 phases that occur during heating in inert atmosphere and in vacuum. A synthetic medium-temperature β-PtBi2 modification corresponding to the mineral insizwaite was studied by high-temperature X-ray diffraction and differential thermal analysis in the temperature range of 20–640°C. Two phase transitions are established by in situ X‑ray powder diffraction: from β into γ-PtBi2, and then into δ-PtBi2. Two endothermic peaks are recorded on the DTA curve, which correspond to the phase transitions. High-temperature X-ray powder diffraction data determined γ- and δ-PtBi2 formation at high temperature in inert atmosphere and in vacuum. Reverse polymorphic transformation were not observed by X-ray powder diffraction during cooling. It is suggested that insizwaite is a mineral geothermometer and its presence in the geological system implies certain temperature ranges of mineral formation environments.

The Central bauxite deposit on the territory of the Russian Federation is a unique geological object. It hosts both primary lateritic bauxites and products of their redeposition (sedimentary lateritic bauxites). The comparative characteristic of the residual in situ lateritic bauxites and sedimentary lateritic bauxites and the study of the morphology of ore-forming minerals of bauxites and their composition allowed us to reconstruct in details the genesis of laterite profiles and sedimentary bauxite-bearing deposits, which has universal significance for understanding supergene mineral deposits. The prospects of using bauxites for REE by-products is shown by the example of the Central deposit of the Chadobets Uplift.

AbstractThe crystal structure of arsenopalladinite, Pd8As2.5Sb0.5, from the Kaarreoja River, Inari commune, Finnish Lapland, Finland, was solved to R1 = 0.0451 on the basis of single-crystal X-ray diffraction data. The mineral is triclinic, space group P$\bar{1}$. The unit-cell parameters are: a = 7.3344(7), b = 7.3870(8), c = 7.5255(7) Å, α = 98.869(8), β = 102.566(8), γ = 119.096(11)°, V = 331.19(7) Å3 and Z = 2. The crystal structure of arsenopalladinite consists of an alternation of layers made by pnictogen (As, Sb) and layers made by palladium atoms stacked along the c axis. Arsenic and (As, Sb) nets exhibit a triangular topology (A and D nets), whereas palladium layers show triangular or pentagon–triangular nets (B and C nets). The unit-cell contains 6 layers, with the ABCDCBA stacking sequence. Although arsenopalladinite shows characteristics very similar (nets of the same topology) to the closely-related mineral mertieite-II, Pd8Sb2.5As0.5, it has a different stacking sequence.

Nipalarsite, Ni8Pd3As4, is a new platinum-group mineral discovered in the sulfide-bearing orthopyroxenite of the Monchetundra layered intrusion, Kola Peninsula, Russia (67 degrees 52'22 '' N, 32 degrees 47'60 '' E). Nipalarsite forms anhedral grains (5-80 mu m in size) in intergrowths with sperrylite, kotulskite, hollingworthite, isomertieite, menshikovite, palarstanide, nielsenite and monchetundtraite enclosed in pentlandite, anthophyllite, actinolite and chlorite. Nipalarsite is brittle, has a metallic lustre and a grey streak. In plane-polarised light, nipalarsite is light grey with a blue tinge. Reflectance values in air (in %) are: 46.06 at 470 nm, 48.74 at 546 nm, 50.64 at 589 nm and 54.12 at 650 nm. Values of VHN20 fall between 400.5 and 449.2 kg.mm(-2), with a mean value of 429.9 kg.mm(-2), corresponding to a Mohs hardness of similar to 4. The average result of 27 electron microprobe wavelength dispersive spectroscopy analyses of nipalarsite is (wt.%): Ni 44.011, Pd 28.74, Fe0.32, Cu 0.85, Pt 0.01, Au 0.05, As 25.42, Sb 0.05, Te 0.39, total 99.85. The empirical formula (normalised to 15 atoms per formula unit) is: (Ni8.10Fe0.06)(Sigma 8.16)(Pd2.94Cu0.18)(Sigma 3.12)(As3.68Te0.03)(Sigma 3.71) or, ideally, Ni8Pd3As4. Nipalarsite is cubic, space group Fm (3) over barm, with a = 11.4428(9) angstrom, V= 1498.3(4) angstrom(3) and Z= 8. The strongest lines in the powder X-ray diffraction pattern of synthetic Ni8Pd3As4 [d, angstrom (I) (hkl)1 are: 2.859(10)(004), 2.623(6)(313), 2.557(6)(024), 2.334(11)(224), 2.201(35)(115,333), 2.021(100)(044), 1.906(8)(006,244) and L429(7)(008). The crystal structure was solved and refined from the single-crystal X-ray diffraction data of synthetic Ni8Pd3As4. The relation between natural and synthetic nipalarsite is illustrated by an electron back-scattered diffraction study of natural nipalarsite. The density calculated on the basis of the empirical formula of nipalarsite is 9.60 g.cm(-3). The mineral name corresponds to the three main elements: Ni, Pd and As.

The new mineral novograblenovite, (NH4,K)MgCl3 center dot 6H(2)O, was found on basaltic lava from the 2012-2013 Tolbachik fissure eruption at the Plosky Tolbachik volcano, Kamchatka Peninsula, Russia. It occurs as prismatic, needle-like transparent crystals together with gypsum and halite. Novograblenovite was formed due to the exposure of the host rocks to eruptive gas exhalations enriched in HCl and NH3. Basalt was the source of potassium and magnesium for the mineral formation. Novograblenovite crystallises in the monoclinic space group C2/c, with unit-cell parameters a = 9.2734(3) angstrom, b = 9.5176(3) angstrom, c = 13.2439(4) angstrom, beta= 90.187(2)degrees, V = 1168.91(2) angstrom(3) and Z= 4. The five strongest reflections in the powder X-ray diffraction pattern [d(obs), angstrom (I, %) (h k l)] are: 3.330 (100) (2 2 0), 2.976 (45) ((1) over bar 1 4), 2.353 (29) ((2) over bar 2 4), 3.825 (26) (2 0 2), 1.997 (25) ((4 2) over bar 2). The density calculated from the empirical formula and the X-ray data is 1.504 g cm(-3). The mineral is biaxial (+) with alpha = 1.469(2), beta = 1.479(2) and gamma = 1.496(2) (lambda = 589 nm); 2V(meas.) = 80(10)degrees and 2Va(calc.) = 75.7 degrees. The crystal structure (solved and refined using single-crystal X-ray diffraction data, R-1 = 0.0423) is based on the perovskite-like network of (NH4,K)Cl-6-octahedra sharing chlorine vertices, and comprises [Mg(H2O)(6)](2+) groups in framework channels. The positions of all independent H atoms were obtained by difference-Fourier techniques and refined isotropically. All oxygen, nitrogen and chlorine atoms are involved in the system of hydrogen bonding, acting as donors or acceptors. The formula resulting from the structure refinement is [(NH4)(0.7)K-0.3]MgCl3 center dot 6H(2)O. The mineral is named after Prokopiy Trifonovich Novograblenov, one of the researchers of Kamchatka Peninsula, a teacher, naturalist, geographer and geologist.

Ванадиевый травяно-зеленый дравит обнаружен в маломощных (до 10 см) кварцевых жилах, пересекающих черные кремнистые сланцы позднего протерозоя, обогащенные ураном и ванадием (до 50 ppm). Содержание V2O3 в – до 5.34% при низком содержании железа и повышенном магния. По всей вероятности, ванадий занимает в структуре минерала в основном Z-позицию. Получены спектры диффузного отражения в диапазоне 350–2500 нм и люминесценции при возбуждении УФ-излучением N-лазера. Появление ванадия в качестве хромофора и люминофора в метаморфических породах интерпретируется как индикатор древних океанических структур на континентах. В статье 11 рисунков, 2 таблицы, 21 литературная ссылка.

ABSTRACTThe crystal structure of the mineral mertieite-II from the Kaarreoja River, Inari commune, Finnish Lapland, Finland, was refined to R1 = 0.0222 (I) and 0.0228 (II) on the basis of X-ray diffraction data collected from two single crystals. The mineral is trigonal, space group is $R\bar 3c$. The unit-cell parameters for the two crystals are determined as: a = 7.5172(3), c = 43.037(2) Å, V = 2106.1(2) Å3 (I); a = 7.5135(4), c = 43.003(3) Å, V = 2102.4(3) Å3 (II) with Z = 12. The occupancies of the Sb and As position in the structure were refined according to the Sb:As ratio of each crystal. The position As1 (Wyckoff 6b) is completely filled by As atoms. Any excess of As is distributed together with Sb on structural position M1 (Wyckoff 12c). The crystal chemical formulae are defined as Pd8Sb1.5(Sb0.94As0.06)As0.5 (crystal I) and Pd8Sb1.5(Sb0.88As0.12)As0.5 (crystal II). As → Sb substitution of up to 4.50 wt% of As does not affect the main structural topology of mertieite-II. Mertieite-II, Pd8Sb2.5As0.5 and synthetic Pd8Sb3 are isotypic compounds. The crystal structures of synthetic Pd8Sb3 and natural mertieite-II, Pd8Sb2.5As0.5, can be derived from the hexagonal close packing by filling additional layers between the close-packed 36 layers. The structure consists of Sb and (Sb,As) triangular 36, Pd triangular 36 and Pd pentagonal-triangular 5.33 layers. Stacking of Sb-, (Sb,As)- and Pd-nets along the z axis caused extension of the unit cell. It contains a total of 36 layers: six Sb1-nets, six (M1,As1)-nets, 12 Pd1-nets and 12 (Pd1,Pd3,Pd4)-nets.