Freibergite Series of Fahlore in the Mangazeyskoye Epithermal Silver–Polymetalic Deposit (West Verkhoyansk Region, Yakutia, Russia): Intergrowths, Heterogeneity, Chemical Composition, and Formation Conditions

Quartz is one of the most abundant minerals in the Earth’s crust and the most important silica mineral, occurring in large amounts in igneous, metamorphic and sedimentary rocks. The mineral is widely used as a raw material in several industrial applications. Because of its chemical composition (SiO2) and its specific properties, quartz can be used both as a bulk product (e.g. quartz sands in the glass or foundry industry) and as a high-tech material (e.g. piezo or optical quartz).Dependent on the specific conditions of either natural or synthetic formation, quartz can display typomorphic properties. Variations in crystal shape, specific micro-structure, trace element or isotope compositions, characteristic spectroscopic properties, etc. may be controlled by the genesis of the quartz involved. Accordingly, the defect structure of quartz is a fingerprint of its conditions of formation. A knowledge of the interrelation between quartz genesis and the specific properties developed at that time can be used both for the reconstruction of geological processes and for specific technical applications. Selected examples in the present study give an overview of how to analyse and use the specific information inherent in the mineral quartz.

Ferrospheres from fly ashes of Chelyabinsk coals: chemical composition, morphology and formation conditions

How to link the relative abundances of gas species in coma of comets to their initial chemical composition?

Background. Septaria, comprising calcareous-clay nodules with calcite veins, are widely used as jewelry and ornamental materials. Septaria from Morocco represented on the world and Russian markets of jewelry and ornamental stones remain gemologically and mineralogically underexplored. In this article, the gemological characteristics and mineral composition of Morocco septaria, as well as the conditions of their formation, are described for the first time.Aim. To determine the gemological characteristics and mineral composition of Morocco septaria, as well as their formation conditions. To conduct their comparison with septaria from other regions of the world.Materials and methods. The author studied the assortment of Morocco septaria presented at international and Russian exhibitions. A collection (15 samples) representing the main decorative septarium varieties was compiled. The materials underwent determination of microhardness, density, luminescence (10 samples), optical-petrographic analysis (4 sections), quantitative determination of mineral and chemical composition (2 samples), electron probe studies (2 samples).Results. The septaria were found to consist of (wt %): quartz — 38, goethite — 16, chlorite (shamosite) — 28, kaolinite — 6, siderite — 5, dolomite — 4, calcite — 1, pyrite, zeolite, apatite, hydrosludes less than 1. Dispersed inclusions of leucoxene, barite, and microcline were discovered. The septarium veins consisted mainly of dolomite, quartz, chlorite with inclusions of siderite, calcite and pyrite. The Zn, Sr, and Ba impurities ranged within 0.01—0.05 wt %, while Cr, V, Ni, Cu, Rb, Zr, Y, and Pb ranged within 0.001—0.01 wt %. The mineral composition of the studied Morocco septaria was found to differ significantly from that of septaria in other regions of the world, where calcite plays a decisive role.Conclusion. Morocco septaria of small size (from 2 to 6 cm) are used as interior decorations and jewelry cabochons. The mineral and chemical (including micro-inclusions and impurities) composition of Morocco septaria was established for the first time, which allows their identification. The mineral composition of the septaria under study is associated with the regional low-temperature metamorphism, which altered the original, predominantly calcite composition.

The reduction of permafrost top and the increase in ground temperature lead to the risk of gas manifestations from thawing permafrost. Gas-saturated epigenetic marine permafrost deposits, as well as certain types of ground ice in Yamal, pose a potential danger of greenhouse gas emissions into the atmosphere. A study of the genesis of ground ice in the Vaskiny Dachi geocryological research station was conducted from 2019 to 2021. Four types of ground ice were studied in the sediments of the III plain in Central Yamal – relict ice, pseudomorphs, lens ice and massive ice. The work aims to investigate the genesis of ground ice and its relationship with host deposits in the context of climate change. Based on data on the patterns of ice occurrence in natural outcrops, the lithological composition of the host deposits, and the petrological characteristics of the ice in thin sections, the authors propose to identify geochemical markers indicating the genesis of the ice. The cryolithological structure was established, the lithological composition of the deposits was determined using a laser granulator, and the ionic composition of the ice and deposits was defined using ionometric titration, titrimetry, atomic absorption, atomic emission, turbidimetry, and ionometry methods. The structure and texture of the ice, as well as its ionic and elemental composition, were studied using inductively coupled plasma mass spectrometry. A relationship was established between the chemical composition, texture, and structure of relict, lens-shaped, massive ice, and host deposits. In the upper part of the section at the boundary of the lake sediment layer, continental salinization was identified, whereas in the lower part, the chemical composition indicates coastal-marine conditions. The ionic composition confirms the coastal-marine genesis of the massive ice; a saline pseudomorph was distinguished, differing in structure and texture of the ice and chemical composition from relict ice. The distribution of rare earth elements allowed for the determination of the conditions of ice formation. Lens-shaped ice and pseudomorphs exhibit negative cerium and positive europium anomalies, unlike relict ice. It was established that freezing occurs in water-saturated conditions for massive, lens-shaped ice, and pseudomorphs. The applicability of geochemical markers for clarifying the conditions of ground ice formation and the genesis of deposits, taking into account the cryolithological structure of the sections, was justified.

Among the many mysteries of our Universe, one still unanswered question is how globular clusters form. Globular clusters are very dense agglomerates of hundreds of thousands of stars and they host some of the oldest known stars in our Universe. Since they are luminous, old and found in all massive galaxies, they are a fundamental piece of the puzzle to understand galaxy formation and evolution processes. Traditionally, globular clusters were thought to be simple stellar systems, in which all stars were born at the same time and have the same chemical composition. %Therefore, globular clusters have been considered the perfect laboratory to study how stars evolve. However, in the last few decades, it has been shown that stars within a given globular cluster display inhomogeneities in their chemistry. Every massive old globular cluster located in the Milky Way, for which high precision and deep observations were obtained, was found to host several different stellar populations, i.e. multiple populations. Each stellar population is characterized by specific chemical patterns observed in the atmospheres of individual stars. Only certain elements are found to vary, and they do not do so randomly, but rather the variations are observed to correlate between the elements. The stellar population that has enhanced nitrogen (N) content, also has enhanced sodium and helium abundances but has a depletion in carbon and oxygen, to cite a few examples. At the same time, the iron content is found to be constant among the different populations. Such chemical patterns are often called anomalies. More interestingly, it seems like such chemical anomalies are unique to globular cluster systems, i.e. dense stellar systems, since they are basically not found in other stars located in the field. Knowing how such multiple populations form and how they impact the evolution of globular clusters is crucial to understand the formation of stars and clusters themselves and, more broadly, the formation and evolution of galaxies. Many theoretical scenarios have been proposed to explain the origin of the chemical anomalies in globular clusters. Most models treat the origin of this phenomenon as multiple events of star formation. In such models, a first generation of stars forms from the collapse of a giant molecular cloud which is homogeneous in its chemical composition. The winds of the massive stars from this first generation sink in the centre of the cluster to collapse and provide material for a second generation of stars, which then forms with a different chemical composition. While theoretically straightforward, such scenarios (which involve many types of massive stars) fail in reproducing many of the observed properties of multiple populations in globular clusters. Hence, the formation mechanism for the origin of multiple populations remains an open question. Most studies of multiple populations focused only on ancient globular clusters, aged up to $\sim$13 Gyr. However, many dense and massive younger star clusters are observed in nearby galaxies. Is the multiple populations phenomenon limited to the ancient globular clusters, i.e. could this be a cosmological effect? The goal of this thesis has been expanding the search for multiple populations to star clusters that are significantly younger than the old globular clusters, i.e. up to 10 times younger. Indeed, a compelling line of investigation is to look for multiple populations depending on certain global properties of the clusters, such as age, mass, metallicity. The first major result presented in this work is that multiple populations are found also in the young clusters, down to $\sim$2 Gyr old objects, showing that the phenomenon of multiple populations is not only restricted to the early Universe. Another interesting result I report is that the extent of the multiple populations (in chemical abundance spread) is a strong function of age, with older clusters having larger chemical variations. Additionally, I show that there is no difference in age between the populations in a young star cluster. Such results represent fundamental constraints for the origin of multiple populations and might point towards a new and fresh direction into the onset of this complex phenomenon. An important and related question is whether the young massive star clusters are the same type of stellar systems as the ancient globular clusters, just observed at a different stage of their lifetimes. If confirmed, this could provide important constraints on star cluster formation studies. Therefore, in this thesis I explored clusters at younger ages in order to address the fundamental question whether the star (and cluster) formation conditions were different in the early Universe. The results presented here represent an important hint that ancient and young clusters share the same origin and are only separated in age. I show that star clusters do not require special conditions in which to form, so that they can be used as tracers for the formation and evolution of galaxies.

This article shows the prospect of the system BaO–Al2O3–B2O3–SiO2 as the basis of vitreous and glass ceramic materials, which are widely used in rocket production for high-temperature protection of heat resistant alloys, in the power industry for sealing solid oxide fuel cells, and in the production of heat resistant glass ceramic materials. We examined the conditions of glass formation and properties of glasses with the following content of components (mol.%): BaO 30–70, B2O3 10–50, SiO2 20–60, and Al2O3 0–10. We established experimentally that the physical and chemical properties of glass, depending on its chemical composition, vary within the following limits: coefficient of linear thermal expansion of (71–122)10–7 К–1; glass transition temperature of 500–6500С; dilatometric softening point of 540–6700С; and density of 3.20–4.21 g cm–3. The volume resistivity of the studied glasses is within 1011–1013 Ohmcm at the temperature of 1500С. Generalization of the dependences of glass properties on their chemical composition was carried out with the use of the additive equations, for which the partial contributions of oxides to the values of the corresponding properties were determined by experimental and statistical methods. The established patterns of influence of components and conditions of glass formation on the physical and chemical characteristics of glasses allows implementing the process of designing of a wide range of glass compositions with the complex of specified properties in order to solve the tasks of their practical use.

Abstract. Gas-particle equilibrium partitioning is a fundamental concept used to describe the growth and loss of secondary organic aerosol (SOA). However, recent literature has suggested that gas-particle partitioning may be kinetically limited, preventing volatilization from the aerosol phase as a result of the physical state of the aerosol (e.g. glassy, viscous). Experimental measurements of diffusion constants within viscous aerosol are limited and do not represent the complex chemical composition observed in SOA (i.e. multicomponent mixtures). Motivated by the need to address fundamental questions regarding the effect of the physical state and chemical composition of a particle on gas-particle partitioning, we present the design and operation of a newly built 0.3 m3 continuous-flow reactor (CFR), which can be used as a tool to gain considerable insights into the composition and physical state of SOA. The CFR was used to generate SOA from the photo-oxidation of α-pinene, limonene, β-caryophyllene and toluene under different experimental conditions (i.e. relative humidity, VOC and VOC∕NOx ratios). Up to 102 mg of SOA mass was collected per experiment, allowing the use of highly accurate compositional- and single-particle analysis techniques, which are not usually accessible due to the large quantity of organic aerosol mass required for analysis. A suite of offline analytical techniques was used to determine the chemical composition and physical state of the generated SOA, including attenuated total reflectance infrared spectroscopy; carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis; 1H and 1H-13C nuclear magnetic resonance spectroscopy (NMR); ultra-performance liquid chromatography ultra-high-resolution mass spectrometry (UHRMS); high-performance liquid chromatography ion-trap mass spectrometry (HPLC-ITMS); and an electrodynamic balance (EDB). The oxygen-to-carbon (O∕C) and hydrogen-to-carbon (H∕C) ratios of generated SOA samples (determined using a CHNS elemental analyser) displayed good agreement with literature values and were consistent with the characteristic Van Krevelen diagram trajectory, with an observed slope of −0.41. The elemental composition of two SOA samples formed in separate replicate experiments displayed excellent reproducibility, with the O∕C and H∕C ratios of the SOA samples observed to be within error of the analytical instrumentation (instrument accuracy ±0.15 % to a reference standard). The ability to use a highly accurate CHNS elemental analyser to determine the elemental composition of the SOA samples allowed us to evaluate the accuracy of reported SOA elemental compositions using UHRMS (a commonly used technique). In all of the experiments investigated, the SOA O∕C ratios obtained for each SOA sample using UHRMS were lower than the O∕C ratios obtained from the CHNS analyser (the more accurate and non-selective technique). The average difference in the ΔO∕C ratios ranged from 19 % to 45 % depending on the SOA precursor and formation conditions. α-pinene SOA standards were generated from the collected SOA mass using semi-preparative HPLC-ITMS coupled to an automated fraction collector, followed by 1H NMR spectroscopy. Up to 35.8±1.6 % (propagated error of the uncertainty in the slope of the calibrations graphs) of α-pinene SOA was quantified using this method; a considerable improvement from most previous studies. Single aerosol droplets were generated from the collected SOA samples and trapped within an EDB at different temperatures and relative humidities to investigate the dynamic changes in their physiochemical properties. The volatilization of organic components from toluene and β-caryophyllene SOA particles at 0 % relative humidity was found to be kinetically limited, owing to particle viscosity. The unconventional use of a newly built CFR, combined with comprehensive offline chemical characterization and single-particle measurements, offers a unique approach to further our understanding of the relationship between SOA formation conditions, chemical composition and physiochemical properties.

Chemical and oxygen isotopic compositions, age and origin of gem corundums in Madagascar alkali basalts

Clay minerals widely occur as a product of the water-rock interaction in hydrothermal, diagenetic and weathering systems at the surficial part of the earth. They show highly diverse and systematic variations in mineralogical properties related to their localities and occurrences. The mineralogical properties of the clay minerals such as mineral chemistry, mixed-layer structure, polytype, particle size, etc., have been investigated to understand the environmental conditions of mineral formation. Recent studies on the chemical compositions and the particle size of clay minerals show that they can be linked to the physicochemical conditions and/or hydrogeological conditions of water-rock interactions performed in the surficial geologic systems. The chlorite geothermometer which links the chlorite compositions to temperature conditions of formation, is highly applicable as a physicochemical index of the water-rock interaction at hydrothermal systems. The particle size properties of clay minerals can be related to their crystal-growth mechanisms and to the hydrogeological conditions of mineral formations, in the water-rock interaction including kinetic reaction. These suggest that the chemical composition and the particle size property of clay minerals are usable as a mineralogical indicator also in exploration of natural resources hosted in the surficial parts of the earth.

The article analyzes the natural mineral waters of the Chechen Republic which are a leading factor in the formation of a sanatorium and health resort base. The conditions of formation and distribution of natural mineral waters on the territory of the Chechen Republic are studied, their classification by chemical composition, general mineralization and balneological properties is presented. Five water-bearing zones within the region are identified and characterized. A brief historical analysis of the research and development of mineral springs is given. A detailed description of mineral springs from the point of their use for balneological purposes is given. On the territory of the Chechen Republic, there are mineral springs with various chemical composition and balneological properties, which are comparable by some properties to the best world analogues, and this creates significant prerequisites for expanding the existing sanatorium and health resort base. At this stage, the main focus should be concentrated on meeting domestic needs, solving the problem of recreation and treatment of residents of the Chechen Republic, and in the future, it should be focused on the development of domestic and international tourism and recreation.

Eclogites from the upper mantle beneath the Kasai Craton (Western Africa): Petrography, whole-rock geochemistry and U[sbnd]Pb zircon age

Both the reaction pathways that lead to the formation of the solid electrolyte interphase (SEI) on the negative electrode of a lithium ion battery and the chemical, electrochemical and physical properties of the SEI are not well understood. Consequently, a full control of the SEI composition and properties through the selection of appropriate formation conditions is far from being achieved. In this contribution we present the influence of the formation potential on the chemical and electrochemical properties of SEIs formed on model carbon electrodes. Our results show that, on HOPG, SEI is formed via a two-step process, where the step occurs at respectively ~700 and ~400 mV vs. Li/Li+. The SEIs that are formed at potentials corresponding to the first or the second potential step exhibit drastically different characteristics in terms of chemical composition, thickness and transport properties. Our results are consistent with electrochemical investigations that are performed on commercial composite carbon electrodes. The SEI formed at higher potentials appears to be disadvantageous for Li+ ion intercalation. A further reduction of the SEI at lower potential is required to improve the intercalation. The still debated mechanism of transition metal deposition on the anode of Li-ion batteries was also investigated on model HOPG electrode surfaces exposed to contaminated electrolyte after completion of the SEI formation. Our results indicate, that the deposition of transition metals is strongly affected by the nature of the SEI, in particular by its thickness. By introducing transition metal cations in our model system we demonstrate, that the respective deposition takes place at the SEI compact layer surface via an electron tunneling mechanism. Figure 1

This paper reviews experimental research on nanocomposite protective coatings of various chemical compositions and structure. For adaptive multielement and multilayer systems with specific phase composition, structure, substructure, stress state, and high functional properties, formation conditions are considered; the behavior of such systems under extreme operating conditions and in tribological applications is examined; the structural, phase, and chemical composition are discussed as well as the hardness, friction and wear at elevated temperatures; and the adhesive strength of hierarchical protective coatings is analyzed. Finally, the adaptive behavior under different tribological test conditions of multifunctional, multilayer coatings as a function of their properties and structure is examined.

The structure, chemical composition, and properties of palygorskites from several deposits in the Russian Federation, Ukraine, Uzbekistan, and Slovakia have been investigated by transmission electron microscopy, microanalysis, X-ray diffraction, IR spectroscopy, and thermal analysis. It is shown that the palygorskites formed under different physicochemical conditions may significantly differ in chemical composition, morphology, and defect structure. Depending on the formation conditions, palygorskites decompose differently upon heating.