Infrared spectroscopic analysis of palygorskite clay from the Dashkovskoye and Borshchevskoye deposits yielded key insights into the sedimentation conditions prevailing in the study area. In this paper, the composition, structure, and adsorption properties of smectite-palygorskite clays from the Steshevian sub-stage of the Lower Carboniferous (Russia) are investigated. The study applied X-ray diffraction, infrared spectroscopy, scanning electron microscopy, assessment of cation exchange capacity by adsorption of [Cu(trien)2+], assessment of Cs sorption, and particle size analysis. It is demonstrated that the Al-palygorskite of the Dashkovskoye deposit was formed by sedimentation from suspended matter in a shallow-water basin in the Steshevian sub-age, despite a different genesis (chemogenic in the case of the palygorskites, clastic/redeposited in the case of the smectites). The palygorskites of the Borschovskoye deposit have a complex terrigenous genesis and were formed from redeposited chemogenic Al-palygorskites transported into the basin from the surrounding region of the Dashkovskoye deposit. With increasing depth of the basin in the Steshevian sub-age, the volume of incoming palygorskite material decreases, and the proportion of smectite material increases. The Fe-palygorskites entered the Borschovskoye deposit due to the redeposition of sediments from soils upstream of water flows. All the studied clays have considerable adsorption properties (32-49 mg-eq/100 g) and can be used in various industries.

Synthetic alumosilicates are used in many industrial applications, and the synthesis of clay minerals under different conditions allows us to understand the conditions of their formation. This study examined the impact of varying silica precursors, pH conditions and synthesis durations. Synthetic kaolinite group mineral analogues were investigated by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. Additionally, the crystallinity index was calculated. The impact of using different silica sources on the structural features of synthetic kaolinite group analogues was revealed. The use of a Nanosil precursor resulted in the formation of highly crystalline kaolinite. The most significant alterations in the course of synthesis were observed at different pH values. The formation of various synthetic analogues of minerals from the kaolinite group was observed: at a high pH, the formation of halloysite with a small admixture of kaolinite was observed. Conversely, the synthesis resulted in the formation of ordered kaolinite at a low pH. The crystallinity index of the resulting synthesized kaolinite analogues rises as the synthesis duration increases, while the quantity of non-crystallized material decreases. The changes in the crystallinity of kaolinite when using different silica precursors are related to the different homogenization of the material that occurs at the stage of alumosilica gel formation.

The features of the transformation of andesites of the East Pauzhetka thermal field under the influence of the argillization process are studied based on a number of samples with different degrees of alteration, which were taken from boreholes and outcrops near the study object. The main patterns of changes in the composition and physical and mechanical properties of andesites have been revealed. A schematic diagram of the structure of the thermal field in section has been compiled; this diagram distinguishes three horizons from bottom to top, showing an increase in the degree of hydrothermal transformation: altered andesites, metasomatic breccias, and hydrothermal clays.

Due to various historical events, in the Russian Federation, in addition to the radioactive waste storage facilities used in world practice, there are various nuclear and radiation hazardous facilities that require special procedures for monitoring and decommissioning. One of these facilities is the disposal site for LRW on the territory of the JSC Siberian Chemical Plant, where specially prepared waste is injected into sand reservoirs lying at depths of 300–350 m between clayey strata. This study examines in detail the features of the lithological and mineral composition of reservoir sands and aquitards. The processes of environmental transformation in reservoir sands, which lead to changes in the composition and structure of rocks, were characterized. These processes manifest themselves in the form of the development of leaching zones and their “healing” with newly formed smectite, the destruction of terrigenous grains, including the development of cracks, and the growth of newly formed smectite in the pore space of reservoirs. The forms of occurrence and localization of authigenic smectite formed as a result of technogenic impact are described. It has been shown that, despite the obvious impact of highly reactive solutions accompanying liquid radioactive waste, the insulating properties of the geological environment are maintained and even improved to some extent.

An acoustic technique for nondestructive testing of the degree of local microcracking in laboratory mineral samples based on laser generation of ultrasound is proposed. The spectral power of broadband signals of longitudinal ultrasonic waves is measured. The waves were generated by absorption of pulsed laser radiation in a special material that served as a laser source of ultrasound and further scattered by microcracks in samples (the so-called structural noise power). For two types of feldspars with a nonuniform volumetric distribution of microcracks, a direct relationship was obtained between an increase in microcracks and an increase in the power of structural noise in the sounded sections of the samples. For the first time, an independent method of X-ray computed tomography of complex-shaped samples confirmed the reliability of the results of acoustic measurements. The established relationship between the local microcracking and structural noise power can be used in the monitoring systems for observing the crack formation in rocks and minerals under various external loadings.

—A sequence of argillized rocks and hydrothermal clays of the East Pauzhetka thermal field was studied in detail by means of drilling and trenching. We have identified zones composed of unusual mineral associations; their formation conditions are considered. The structure of the base of the hydrothermal-clay mass is shown. The source rocks (brecciated andesites) of the base are altered by hydrothermal–metasomatic processes and are represented by smectite–chlorite–K-feldspar–zeolite–carbonate–siliceous aggregate with sulfides, phosphates, titanium silicates and zircon silicates, and other mineral phases, including rare metals. A conceptual geological and geochemical model for the formation of argillisites and zones with mineral associations has been plotted. It is assumed that modern mineral formation in the East Pauzhetka thermal field inherits an epithermal ore-forming system located in the influence zone of a deep-seated fluid, the derivates of which are outflowing near the surface as alkaline metal-bearing solutions of the Pauzhetka hydrothermal system.

We have analyzed the surface of a plasma three-dimensional capillary-porous (TDCP) Ti coating with an additional bioactive hydroxyapatite coating formed by microplasma oxidation (MPO). Scanning electron microscopy (SEM) was used to analyze the open porosity of these composite coatings. The surface of the TDCP Ti coating consists of ridges and valleys. The main porosity of the TDCP Ti coating is concentrated within the volume of valleys and reaches 43%. The presence of macro- and micropores 0.08–600 μm in size makes TDCP Ti coatings promising for using in a variety of fields, including as the surface coatings of intraosseous implants.

На Восточно-Паужетском термальном поле с помощью бурения скважин и проходки шурфов детально изучена толща аргиллизированных пород и гидротермальных глин. Выделены зоны, сложенные минеральными ассоциациями необычного состава, рассмотрены условия их образования. Показано строение основания толщи гидротермальных глин, исходные породы которого (брекчированные андезиты) полностью изменены гидротермально-метасоматическими процессами и представлены смектит-хлорит-калишпат-цеолит-карбонат-кремнистым агрегатом с сульфидами, фосфатами, титанои цирконо-силикатами и др. минеральными фазами, включающими редкие металлы. Построена концептуальная геолого-геохимическая модель формирования аргиллизитов и зон, содержащих минеральные рудные ассоциации. Предполагается, что современное минералообразование на Восточно-Паужетском термальном поле наследует эпитермальную рудообразующую систему, расположенную в зоне влияния глубинного восстановленного флюида, дериваты которого разгружаются вблизи дневной поверхности в форме щелочных металлоносных растворов Паужетской гидротермальной системы.

Bentonite clays have unique properties that determine their use as the main component of engineered barrier systems (EBS) for the isolation of radioactive waste. At present, the Russian Federation is elaborating the concept of deep geological disposal of radioactive waste in crystalline rocks of the Yeniseisky site, where bentonite clays play an important role in ensuring the safety of the repository for a long period of time. This work demonstrates the first results of short-term laboratory experiments (1 and 3 months) on the thermochemical interaction of bentonite and concrete in the presence of synthetic water at an elevated temperature. These experiments will help predict the effect of EBS materials on montmorillonite. Bentonite from the 10th Khutor deposit (Russia) and Portland cement were used in the experiments. At the first stage of the experiments, solutions were obtained after leaching the concrete with a synthetic groundwater solution for 1 month at 90 °C. At the second stage, the interactions of the obtained solutions with bentonite at 90 °C were studied. As a result of the experiments, the processes of concrete leaching were revealed, which changed the composition and acidity (an increase in the pH from 6.1 to 12.1) of the synthetic water and led to an increase in the porosity of the material in contact with the solution. However, no dissolution of montmorillonite was observed, and the changes were quite small. The research results show the high stability of bentonite from the 10th Khutor deposit under model conditions, which was confirmed by modeling. Thus, we can say that at pH ≈ 12 and at elevated temperatures, montmorillonite retains a stable structure for a long time, which is important for ensuring the safety of disposal in general.

This article studies the geological structure, mineralogical composition, genesis and industrial properties of bentonite of the 10th Khutor deposit (Republic of Khakassia, Russia). The deposit is confined to the coal-bearing formation of Carboniferous age and is one of the main sources of bentonite for the metallurgical and foundry industries in Russia. The samples were collected during several field seasons and were studied with XRD, SEM, DTA, XRF, FTIR, BET and CEC analysis. The deposit consists of 6 productive layers with montmorillonite of alkaline-earth type varying in content from 38 to 72%. The formation of bentonites is associated with the alteration of volcanic ash of rhyodacite and dacite composition in zones of shallow sea water - bays and lagoons. The specific conditions of the formation, like an evaporitic depositional environment with high concentrations of soluble salts and burial diagenesis, as evidenced by seams and packs of hard coal, affected the textural and surface properties of the bentonite and caused the observed low microporosity and limited illitization.

The picturesque and high conservation value thermal landscapes of the Valley of Geysers feature endothermal (heated by endogenous fluids) soils which support endangered and unique species. However, such soils have not been distinguished as a separate taxon within most classification systems. In this study, we described the soil morphology at macro-, meso- and micro-scales, chemistry, mineralogy and vegetation of these landscapes as they are affected by the steam-heated acid-sulfate waters. The studied catenary sequence from exothermal (non-heated) to endothermal soils was characterized by decreasing contents of soil organic carbon, sand fraction, essential nutrients (Ca, K, Mg, Mn and Si), increasing soil acidity, amounts of fine particle-size fractions and contents of trace elements (Al, As, Co, Cr, Cu, Fe, Pb, Ti and V) as well as the development of sodium-sulfate salinity, kaolinization and ferrugination. In phytocenoses supported by endothermal soils, species of order Rosales and Asparagales were overrepresented among obligate and facultative thermophytes respectively, and species of order Poales were underrepresented among facultative thermophytes in relation to the flora of the Valley of Geysers. Phytocenoses on the non-heated Andosols were enriched in Polypodiopsida species. The results of our comparative analysis of the thermally-induced variability in the soils and vegetation contribute to the general understanding of mineralogical, bio-abiotic and biological systems affected by steam-heated acid-sulfate waters. We hope that our findings will provide a basis for future transdisciplinary studies of the influence of steam-heated waters of a hot spring on the thermal landscapes.

An analysis of the surface of a plasma three-dimensional capillary-porous (TCP) Ti coating with an additional bioactive hydroxyapatite coating formed by microplasma oxidation (MPO) has been performed. Scanning electron microscopy (SEM) analyzed the open porosity of these composite coatings. The surface of the TCP Ti coating consists of ridges and depressions. The porosity of the TCP Ti coating of the depressions reaches 43 %. The presence of macro- and micropores with a size of 0.08 – 600 µm makes the TCP Ti coatings promising for use in a number of areas, including on the surface of intraosseous implants.

Carbonate concretions are formed at the base of a sequence of hydrothermal clay in the South Kambalnyi Central Thermal Field situated in the southern part of the Kambalnyi volcanic mountain range, Kamchatka. The concretions have complex chemical and mineral compositions: apart from aragonite which is the main component of each layer, the chemical compounds identified there include oxides of iron and silicon, sulfates of calcium and barium, sulfides of iron and other metals, carbonates of iron and manganese, siliceous ferromanganese formations, nitrogen compounds, and phosphates of calcium and rare metals. The concretions have diverse structures and textures that indicate a multiphase character of formation for these mineral aggregates. It is thought that their formation was due to the discharge of deep-seated alkaline metalliferous solutions in a zone of rock argillization of the South Kambalnyi Central Thermal Field.

Porous coatings are actively used in engineering practice. The porous coating determines the reliability of the operation of the intraosseous implant and the heat transfer process when the aggregate state of the refrigerant is changed. The choice of method for quantitative analysis of porosity is determined by the structure of the coating. In this study, plasma coatings sprayed from powders were analyzed. A porosity of 10.3% inside the alumina coating was analyzed by mercury porosimetry. The main volume of the porosity of the coating is formed by pores ranging in size from 0.13 to 0.36 μm; their share in the total volume is 68.29%. The remaining volume is distributed in sizes of 0.04–0.12 mm, 0.58–4.66 mm, and 5.66–18.2 mm. Microtomography makes it possible to get a more complete general idea of the macro- and microstructure of coatings, establishing the mechanisms of its formation, and to obtain data on the real shape of the pores. A quantitative description of the visible pores of three-dimensional capillary-porous 3CaO⋅Al 2 O 3 coatings in the form of ridges and depressions was determined by raster image analysis using special STIMAN programs. The porosity of this coating is 39.7% of the distribution over four pore groups: 0.74–3.56, 4.34–11.57, 14.08–55.65, 67.73–267.71 mm.

10th Khutor deposit is located in the Republic of Khakassia and confined to the coal-bearing formation of Carboniferous age within the development of continental tuff-sandy-argillaceous sediments. In terms of mineral composition, bentonites are mainly composed of Al-rich montmorillonite. The content of montmorillonite reaches a maximum of 70-75%, with an average content of 55 to 70%. It is one of the main sources of bentonite for the metallurgical and foundry industries in Russia. One of the distinctive features of bentonites from the 10th Khutor deposit is that despite the age of the deposit, about 350 million years, and the presence of an initial phase of metamorphism, as evidenced by the formation of hard coal, these bentonites retained the ability to swell and have high thermal stability. The formation of bentonites is associated with the decomposition of volcanic ash of rhyodacite and dacite composition in zones of shallow seawater - bays and lagoons. The properties of bentonite were influenced by the initial stage of metamorphism. The main purpose of this work was to establish the conditions for the formation of this deposit, as well as to study the features of the mineral composition and physicochemical properties of these raw materials. In addition to fundamental issues, the aim of the work was applied research on the properties and quality of bentonites.

Using a sample from a terrestrial hot spring (pH 6.8, 60 °C), we enriched a thermophilic microbial consortium performing anaerobic autotrophic oxidation of hydrothermal siderite (FeCO 3 ), with CO 2 /bicarbonate as the electron acceptor and the only carbon source, producing green rust and acetate. In order to reproduce Proterozoic environmental conditions during the deposition of banded iron formation (BIF), we incubated the microbial consortium in a bioreactor that contained an unmixed anoxic layer of siderite, perfectly mixed N 2 /CO 2 -saturated liquid medium and microoxic (2% O 2 ) headspace. Long-term incubation (56 days) led to the formation of magnetite (Fe 3 O 4 ) instead of green rust as the main product of Fe(II) oxidation, the precipitation of newly formed metabolically induced siderite in the anoxic zone, and the deposition of hematite (Fe 2 O 3 ) on bioreactor walls over the oxycline boundary. Acetate was the only metabolic product of CO 2 /bicarbonate reduction. Thus, we have demonstrated the ability of autotrophic thermophilic microbial consortium to perform a short cycle of iron minerals transformation: siderite–magnetite–siderite, accompanied by magnetite and hematite accumulation. This cycle is believed to have driven the evolution of the early biosphere, leading to primary biomass production and deposition of the main iron mineral association of BIF.

High inputs of easily available organic matter to the subsurface may quickly activate the native microbial communities, thereby changing soil engineering properties. We studied the effect of glucose addition, an easily available carbon source, on stress-strain properties, mineralogy, and microstructure of several loamy and sandy soils over 30 days in laboratory experiments. During the period of high microbial activity, direct shear tests revealed a reduction of the friction angle of 15-30 % and a raise of cohesion in sands. Unconfined compression tests showed a 20-30 % decrease in the compressive strength of loamy soils. With the decline of microbial activity, the stress-strain properties recovered partially. The alterations of the stress-strain properties with increasing microbial activity were linked to changes in mineralogy and composition. X-ray diffraction showed that the proportion of smectite layers in illite-smectite mixed layer minerals increased, as well as the overall imperfection of clay minerals. Glucose addition resulted in a temporary increase in the content of microaggregates (0.1-0.05 mm). Newly formed linkages of organic matter between solid particles, biofilm formation and direct interaction of cells with mineral surfaces were observed by scanning electron microscopy. Our data show that microbial-mediated processes may adversely influence stress-strain properties of soils and endanger the safety of buildings.

Research is devoted to the problem of recycling waste of the Baikal Pulp and Paper Mill, whose activity has caused serious damage to the ecological environment of Lake Baikal and its environs. Grouting waste production is currently the most effective possible decision to the problem of pollutants, such as sludge-lignin and ash, in water objects and groundwater. The results on the grouting of liquid and solid waste from the Baikal Pulp and Paper Mill, represented by sludge lignin and ash, are presented. Cement, liquid glass, colloidal silica, ammonium persulfate, hydrogen peroxide were used as the main hardeners. Samples were formed by mixing the original waste with astringent. The strength in time, shrinkage, resistance to water were studied. Samples formed on the basis of colloidal silica solution have a maximum uniaxial compressive strength of 0.4 - 0.5 MPa, on the basis of liquid glass—0.2 - 0.3 MPa. Adding fine sand increases the strength by 1.5 - 1.7 times. Samples based on ammonium persulfate and hydrogen peroxide do not have sufficient strength. Adding fine quartz sand increases the strength up to 1.0 - 1.2 MPa.