Rare Mineral Research Articles

Artificial Intelligence and Environmental Impact: Moving Beyond Humanizing Vocabulary and Anthropocentrism.

Artificial intelligence (AI) and its applications in digital health, bioengineering, and society have significant material impacts on the environment owing to AI's vast energy demands and energy consumption, carbon footprints, and water usage to cool data centers and generate electricity to power the data centers. Yet, the environmental footprints of AI remain underappreciated and inadequately acknowledged. This is significant, particularly in this era of climate emergency and ongoing threats to planetary energy and water supplies. The vocabulary attached to AI often aims to mimic positive human capacities such as "warmness" and "care." However, these attempts to humanize AI and digital technology come with an anthropocentric gaze and blind spots that bracket out the environmental impacts and footprints of AI and privilege humans and technology over nonhuman animals and planetary ecological limits. In medicine, the environmental impacts of large language models range from water consumption and carbon emission to rare mineral usage. This commentary and innovation analysis question and queer the popular imagination of AI and digital technology as things that only exist in the immaterial world of cyberspace. In the course of research on AI in planetary health, we must be cognizant of its materiality, ecological impacts, and massive energy and water demands. We argue that moving away from anthropocentric narratives and vocabulary in AI design and praxis would bode well to live within planetary ecological limits so that AI and emerging digital technologies best serve robust and responsible science and all life on the planet Earth.

Harnessing Geo-Diversity: Geosites and Geotourism in Uganda's Albertine Region

The Albertine Region of Uganda, an integral part of the Great Rift Valley, have a diverse array of geosites with exceptional geoheritage value. Despite the region's immense geological, geomorphological, structural, palaeontological, stratigraphic and mineralogical significance, as well as its potential as a prime geotourism destination, there is a scarcity of comprehensive studies on its geoheritage within the global geotourism literature. This research examined and assessed key geosites in the Albertine Region, emphasizing their educational value and unique geological characteristics that could attract geotourists. The study employed a rigorous methodology combining cartographic analysis, scientific literature review, GIS data integration, and field surveys to identify and evaluate the geosites based on their educational and touristic potential. The geosites were classified into thematic groups, including waterfalls, hot springs, glacial features, caves, rare mineral occurrences, and bedrock exposures. The evaluation revealed that several geosites possess considerable geotourism and educational potential, with some receiving high scores for both educational value and geotourism attractiveness. To capitalise on this potential and generate economic benefits for Uganda, a two-pronged approach is recommended, involving collaboration between government agencies and educational institutions to promote geosites and actively identify and develop potential sites. By doing so, the Albertine Region can be transformed into a premium geotourism destination in Uganda, generating economic benefits for the country while safeguarding its invaluable geoheritage.

Environmental impact assessment of granites bearing rare metals mineralization utilizing airborne gamma-ray spectrometric data, Egypt

Environmental impact assessment of granites bearing rare metals mineralization utilizing airborne gamma-ray spectrometric data, Egypt

Environmental impact of large language models in medicine.

The environmental impact of large language models (LLMs) in medicine spans carbon emission, water consumption and rare mineral usage. Prior-generation LLMs, such as GPT-3, already have concerning environmental impacts. Next-generation LLMs, such as GPT-4, are more energy intensive and used frequently, posing potentially significant environmental harms. We propose a five-step pathway for clinical researchers to minimise the environmental impact of the natural language algorithms they create.

Genetic linkage between parent granite and zoned rare metal pegmatite in the Renli-Chuanziyuan granite-pegmatite system, South China

Elucidating the causal relationship between parent granite and pegmatite and tracing the magmatic-hydrothermal evolution and rare metal mineralization are intriguing scientific issues that remain unsolved. The Renli-Chuanziyuan granite-pegmatite field, hosted in and adjacent to the Mufushan batholith, represents a significant rare metal ore district in southern China. The field reveals well-defined regional zonation, encompassing biotite, two-mica, and muscovite monzogranites at the core, which transition outward to microcline (K-pegmatite), microcline-albite (K-Na-pegmatite), albite (Na-pegmatite), and albite-spodumene pegmatites (Na-Li-pegmatite) at the southwestern margin of the Mufushan batholith. The U-Pb ages of the columbite-tantalite (coltan) grains from the Na-Li-pegmatite samples from the Chuanziyuan deposits are 139.1 ± 1.2 Ma and 138.6 ± 1.1 Ma, which are consistent with the ages of the coltan grains from the Renli deposit, indicating contemporaneous mineralization. Chemical analyses of muscovite, garnet, and coltan from various pegmatite zones reveal a gradual increase in the degree of differentiation and volatile components of the Early Cretaceous magmatic system from north to south. Particularly noteworthy is the significant increase in the abundance of Na-Li-pegmatites to the south, signifying the transition from an early melt stage with a minor fluid component to a melt-fluid stage with a substantial volume of unmixed fluid. This evolution led to the enrichment and precipitation of Nb and Ta in the Renli deposit and of Li in the Chuanziyuan deposit, which were facilitated by the separation and exsolution of flux-rich (e.g., F, H2O) fluid. The highly evolved ca. 140 Ma muscovite monzogranite exhibits a well-defined spatial and temporal relationship with rare metal pegmatites, providing strong evidence of genetic associations. Furthermore, the geochemical characteristics of muscovite and garnet from the muscovite monzogranite overlap with those of mineralized pegmatites, further suggesting (together with the simulation study) that the muscovite monzogranite served as the parental granite of the mineralized pegmatites. These findings underscore the importance of understanding the evolution of the granite-pegmatite system, particularly in the context of rare metal exploration, and contribute to a deeper understanding of the ore-forming mechanisms of zoned rare metal pegmatites.

The formation and recycling of Neoproterozoic granitoids in the Jiangnan Orogen, South China: Implications for Mesozoic rare metal mineralization

In the era of energy transition on the Earth, rare metal mineralization has attained increased significance for various energy sectors and understanding their formation and evolution in various tectonic settings is of great importance for formulating exploration strategies. The Neoproterozoic Jiangnan Orogen in South China marks the assembly zone of the Yangtze and Cathaysia blocks and carries numerous rare metal deposits. In this contribution, we investigate the Neoproterozoic Jiuling composite batholith to understand the formation of rare metal mineralization. We present new in-situ zircon U–Pb ages and Lu–Hf isotopes, and whole-rock geochemistry and Sm–Nd isotopes of the Banbei biotite granodiorite and the associated rare metal-mineralized Baishawo granite in the western portion of the Jiuling batholith suite. Zircon U–Pb dating indicates that the Banbei biotite granodiorite, and the Baishawo two-mica granite and muscovite granite formed at ca. 820 Ma, 153 Ma, and 142 Ma, respectively. The εHf(t) values of the biotite granodiorite, two-mica granite and muscovite granite are –4.4 to +5.8, –11.8 to –7.0, and –10.5 to –7.3, respectively. The εNd(t) values of the biotite granodiorite, two-mica granite and muscovite granite are –3.88 to –2.73, –10.6 to –10.2, and –9.23 to –9.16, respectively. Zircon Hf isotopes and whole-rock Sm–Nd isotopes suggest that the granite suite was sourced from the Mesoproterozoic crust. Geochemical modeling suggests that the Banbei biotite granodiorite was derived from partial melting of Meso- to Neoproterozoic metasedimentary rocks, whereas the Baishawo two-mica granite and muscovite granite were derived from assimilation–fractional crystallization of the Neoproterozoic Banbei biotite granodiorite and Mesozoic magma with low degrees of differentiation. Combined with previous studies on the granite suites in the Jiangnan Orogen, we suggest that collision between the Yangtze and Cathaysia blocks ceased at least 820 Ma, and that Precambrian rocks might have contributed significantly to the enrichment of rare metal mineralization in Mesozoic granite through reworking.

Apatite and Monazite Geochemistry Record Magmatic and Metasomatic Processes in Rare Earth Element Mineralization at Mountain Pass, California

Abstract The largest rare earth element (REE) deposit in the United States is a carbonatite intrusion at Mountain Pass in the Mojave Desert, California. Despite a clear spatiotemporal association of alkaline silicate and carbonatite intrusions at Mountain Pass, a genetic model of their mutual formation has not been resolved. The Mountain Pass carbonatite has long been upheld as an example of a primary magmatic body, but this has not been investigated in detail at the mineral scale. This study investigates the geochemistry of apatite and monazite grains from the alkaline silicate and carbonatite stocks and dikes of the Mountain Pass district to elucidate the magmatic history of the intrusive suite and identify the potential role of fluids in REE mineralization. Three apatite populations are identified in the alkaline silicate rocks. A primary magmatic apatite group supports intrusion of the stocks as separate pulses of magma derived from a spatially extensive metasomatized mantle source region. The second group implicates the role of a regional fluid that mobilized light REEs from apatite grains. Low Sr concentrations and negative Eu anomalies in cores of a minor group of inherited apatite support assimilation of crustal material in the formation of the intrusive suite. Analyses of monazite and apatite grains from the carbonatite orebody also reveal a mix of primary magmatic and metasomatic (fluid related) minerals. Compositional similarities between primary phosphates in the carbonatite and alkaline silicate rocks support a genetic link between the intrusions. The impact of fluids on mineralization in the carbonatite orebody indicates the Mountain Pass carbonatite should not be classified as a purely magmatic REE deposit.

Rare and minor minerals of copper-nickel sulfide ores of the Talnakh ore cluster and their impact on beneficiation indicators

Rare and minor minerals of copper-nickel sulfide ores of the Talnakh ore cluster and their impact on beneficiation indicators

Study on selective green leaching of rare earth elements from coal gangue using mechanochemical activation

This study proposes a sustainable method for the selective leaching of rare earth elements (REEs) from coal gangue. By combining 600 °C calcination, the addition of 5 % Fe2(SO4)3, and one hour of mechanical-chemical activation, we achieved a leaching efficiency of 65 % for REEs. This method alters the surface and crystalline structure of coal gangue, facilitating the release of rare earth phosphate minerals and the formation of water-soluble compounds (rare earth sulfates). Fe2(SO4)3 transforms into insoluble iron oxide, which immobilizes impurities and promotes the selective leaching of rare earth elements. Notably, during the leaching process, the leaching rates of aluminum (Al) and iron (Fe) were only 0.37 % and 1.27 %, respectively. Kinetic analysis indicates that this process follows a mixed reaction-controlled shrinking core model. This method effectively reduces the environmental risks associated with traditional acidic reagents, providing a sustainable pathway for the recovery of rare earth elements.

Enhancing Mineral Exploration Programs Through Quantitative XRD: A Case Study from the Gumsberg Polymetallic Sulphide Deposits, Sweden

As challenges in precious and base metal exploration intensify due to the diminishing availability of high-grade ore deposits, rising demand, energy costs, and stricter regulations towards net-zero carbon activities, advanced techniques to enhance exploration efficiency are becoming increasingly critical. This study demonstrates the effectiveness of quantitative X-ray diffraction (QXRD) with Rietveld refinement, coupled with multivariate statistical analysis (including agglomerative hierarchical clustering, principal component analysis, and fuzzy analysis), in characterizing the complex mineralogy of strata-bound volcanic-associated limestone-skarn Zn-Pb-Ag-(Cu-Au)-type sulphide deposits (SVALS). Focusing on 113 coarse rejects from the Gumsberg project located in the Bergslagen mining district in central Sweden, the research identified five distinct mineralogical clusters corresponding to polymetallic base metal sulphide mineralization, its proximal alteration zones, and variably metamorphosed host rocks. The results reveal significant sulphide mineralization, ranging from disseminated to massive occurrences of sphalerite, pyrrhotite, pyrite, and galena, with trace amounts of secondary minerals like anglesite in certain samples indicating weathering processes. The study also identifies rare minerals such as armenite, often overlooked in traditional geological logging. These findings underscore the potential of QXRD to enhance resource estimation, optimize exploration strategies, and contribute to more efficient and sustainable mineral exploration programs. The accuracy of QXRD was cross-validated with geological logs and geochemical data, confirming its reliability as a mineralogical discrimination tool.

Rb enrichment processes in highly evolved granites: Insights from mica and K-feldspar from the Baishitouquan pluton, Eastern Tianshan

Highly evolved granites are closely related to rare metal mineralization. The mechanisms controlling rare metal enrichment, however, remain poorly constrained. The highly evolved Baishitouquan (BST) pluton in the Eastern Tianshan, which hosts the Zhangbaoshan Rb deposit, has been well characterized and provides an excellent opportunity to study Rb enrichment processes in granitic systems. The BST pluton has five lithological zones, which, from bottom to top, are leucogranite (Zone-a), amazonite-bearing granite (Zone-b), amazonite granite (Zone-c), topaz-bearing amazonite granite (Zone-d), and topaz albite granite (Zone-e). To investigate Rb enrichment processes in the BST pluton, compositional variations in K(–Rb)-rich minerals from the different lithological zones are characterized and interpreted in the context of textural variations. The main K- and Rb-bearing minerals in the pluton are mica and K-feldspar, which are mainly represented by phengite and microcline, respectively. Phengite in Zone-e occurs as euhedral grains with irregular boundaries, indicating that they crystalized from the Baishitouquan magma and were overprinted by hydrothermal fluids. Phengite is generally enriched in F (1.05–9.94 wt%), Li (780–10171 ppm), and Rb (3133–6657 ppm), and is characterized by low K/Rb and Nb/Ta ratios. Most microcline grains occur as elongate, euhedral–subhedral laths, with tartan and Carlsbad twinning. These microcline grains are enriched in Rb (1547–2927 ppm), Pb (15–120 ppm), and Cs (14–100 ppm), and have low K/Rb and Al/Ga ratios. In the BST pluton, the concentrations of Li, F, and Rb in phengite increase from Zone-a to Zone-c, then decrease in Zone-d and Zone-e. Conversely, the K/Rb and Nb/Ta ratios decrease from Zone-a to Zone-c, then increase in Zone-d and Zone-e. The Rb concentration and K/Rb ratio of microcline exhibit a similar trend. Considering the gradual changes in lithology among the zones, the variations of mineral chemical from Zone-a to Zone-c implies continuous evolution of the magma dominated by crystal fractionation. The occurrence of secondary mica, and the abrupt geochemical changes in phengite and microcline in Zone-d and Zone-e are indicative of hydrothermal activity. The gradual decrease in Al/Ga ratio of microcline from Zone-d to Zone-e and the presence of secondary mica that is compositionally similar to primary mica suggests that the fluids were magmatic in origin. During magmatic evolution, volatile-rich (e.g., F) melts have lower viscosities and solidus temperatures than volatile-poor melts, allowing them to undergo extreme degrees of fractional crystallization. This significantly enhances the solubility of Rb, leading to continuous enrichment of Rb in the residual melt. As the BST system evolved from one dominated by magmatic processes to one dominated by hydrothermal activity, the crystallization of topaz consumed F, reducing the solubility of Rb in the melt, and leading to a decrease in the concentration of Rb in phengite and microcline. Hydrothermal alteration of phengite would have liberated Rb into the fluids, resulting in lower Rb concentrations in secondary mica compared to primary mica. Therefore, the enrichment of Rb in the BST pluton was mainly controlled by extreme degrees of fractional crystallization of a F-rich granitic magma.

Occurrences of the Rare, REE Minerals Daqingshanite, Törnebohmite, Biraite, Sahamalite, and Ferriperbøeite from the Sheep Creek Area, Montana, USA

Over 30 small, discontinuous, tabular carbonatite bodies are located in the Sheep Creek area, Ravalli County, southwest Montana. The age and origin of these REE-Nb-rich deposits are currently being investigated. The purpose of this paper is to document the occurrence of several rare minerals, including daqingshanite, törnebohmite, biraite, sahamalite, and ferriperbøeite, in two of the carbonatite bodies. These minerals are found in association with monazite, hydroxylbastnäsite, ferriallanite, calcite, dolomite, baryte, quartz, actinolite, apatite, celsian, and Sr-rich aragonite. Automated SEM-EDS was used to target the areas of interest in polished specimens for more detailed spot SEM-EDS and electron probe microanalysis. Raman spectra were also acquired for each of the rare minerals. The complex mineralogy of the Sheep Creek carbonatites is most likely due to several overlapping thermal events, including primary magmatic, overprinting hydrothermal, and supergene weathering stages. The rare minerals described in this study are believed to be hydrothermal and/or carbothermal in origin, although no estimates of temperature are available at this time.

Hydroxyl group dynamics in defernite: Raman spectroscopy studies

A detailed examination of the altered silicate-carbonate xenolith embedded within the ignimbrite of the Upper Chegem Caldera revealed a new occurrence of a rare carbonate mineral known as defernite, with chemical formula Ca6[(CO3)2-x(Si2O7)x/2](OH)7[Cl1-x(H2O)x], where x ≈ 0.4. Defernite crystallizes as colorless to white fibrous aggregates, reaching 100–150 μm diameters. Subsequently, Raman investigations of defernite from the Upper Chegem Caldera were conducted to perform a comprehensive structural analysis and compare it with minerals found in other locations. During this examination, band assignments focused on the carbonate ion vibration (CO32−) with a band at 1085 cm−1 and the hydroxyl group, characterized by a series of strong bands around 3590–3600 cm−1, particularly evident in oriented crystals along the (010) plane. Experimentation involving the alteration of incident laser light polarization highlighted a reduction in the intensity of carbonate and hydroxyl-related bands and the activation of a band around 3390 cm−1. This phenomenon is explained by the formation of hydrogen bonding between hydroxyl groups and chlorine or molecular water, potentially occupying chlorine positions. Lastly, a temperature-dependent experiment demonstrated the instability of the 3390 cm−1 band, which dissipated with increasing temperature. This insight explains the band’s origin around 3590 cm−1, ascribed to non-degenerate hydroxyl groups as a key marker within the defernite structure.

Advanced exploration of rare metal mineralization through integrated remote sensing and geophysical analysis of structurally-controlled hydrothermal alterations

Fusing multi-source (remote sensing and geophysical) data and diverse approaches validation in targeting hydrothermal alteration and structural anomalies enhances the potential for accurately detecting and characterizing mineralization zones. Sentinel 2 data and ASTER were processed for lithological and hydrothermal alteration mapping in the rare metal-rich Umm Naggat area (Egypt). Different image processing techniques were implemented, including false color composites, minimum noise fraction, band rationing, band math, mineral indices, relative absorption band depth, and constrained energy minimization. The rare metal-bearing Umm Naggat younger granite (NYG) pluton was lithologically discriminated and intra-differentiated to mafic-rich biotite granites, mafic-poor alkali feldspar granites, and albitized granites. Extensive hydrothermal alterations, such as albitization, ferrugination, propylitization, argillization, and phyllitization, overprint the NYG pluton. Normalized standard deviation, automatic lineament extractions, and trend analysis highlighted the key structural directions (NW, NNW, NNE, and NE) and distinguished the NYG pluton as a moderate to high structural density zone. The high structural density and intensive alteration zones are spatially associated and more localized within the NYG pluton than the surrounding rocks. Spatial overlay analysis confirmed that the hydrothermal alterations and fluid circulation systems are structurally-controlled. Furthermore, the hydrothermal alteration mapping and structural analysis outcomes were verified by combining fieldwork, slab polishing, petrographic investigations, and mineral chemistry through semi-quantitative scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and quantitative electron probe microanalysis (EPMA) analysis. As a result, the hydrothermal genesis of rare metal-bearing minerals (Nb-rutile, Nb-ilmenite, and columbite) close to or incorporated within alteration minerals (chlorite, muscovite, and hematite) is confirmed from the alteration zones (propylitic, phyllic, and ferruginated). In addition, biotite muscovitization and chloritization significantly contribute to the secondary rare metal enrichment. The current study emphasizes the extensive distribution of secondary rare metal-bearing minerals within the entire NYG pluton (not only limited to the northern albitized granite as depicted by previous studies), which might shed light on these hydrothermally-altered younger granites as a new potential source for Nb and Ta in Egypt.

Quantitatively characterization of rare earth ore by terahertz time-domain spectroscopy

The Bayan Obo deposit is the world’s largest polymetallic associated minerals deposit of rare earths, iron and niobium, and the rarity of its physical properties restrict the knowledge and understanding of its laws. Taking the high-grade mixed rare earth concentrate of Bayan Obo as the research object, terahertz time-domain spectroscopy (THz-TDS) has been adopted for the systematic investigation of high-grade rare earth concentrate base on the traditional X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric-differential thermal analysis (TG-DTA). The absorption coefficient and refractive index of high-grade rare earth ores and their associated minerals of fluorite and dolomite, are all investigated by terahertz time-domain spectroscopy. The terahertz spectral response is affected by the type of mineral and its content. The acquired rare earth terahertz spectral data are processed by correlation analysis. Three machine learning algorithms, Partial Least Squares Regression (PLSR), Random forest (RF) and Multilayer Perceptron (MLP), are used to achieve quantitative detection of their concentrations and components with the coefficient of determination R2 of the absorption coefficient of the optical parameter reaching up to 0.975, 0.992 and 0.984, respectively. This work promotes the growing understanding of terahertz transmission spectroscopy of rare earth-bearing minerals, which can be used to help guide the search for minerals, and to detect, identify as well as quantify them in geology. Terahertz time-domain spectroscopy supplies a new method for study of rare earth resources, and the comprehensive development and utilization of resources in the Bayan Obo deposit.

Geochemical Characteristics and Genesis of Brine Chemical Composition in Cambrian Carbonate-Dominated Succession in the Northeastern Region of Chongqing, Southwestern China

Deeply situated brine is abundant in rare metal minerals, possessing significant economic worth. To the authors’ knowledge, brine present within the Cambrian carbonate-dominated succession in the northeastern region of Chongqing, Southwestern China, has not been previously reported. In this investigation, brine samples were collected from an abandoned brine well, designated as Tianyi Well, for the purpose of analyzing the hydrochemical characteristics and geochemical evolution of the brine. Halide concentrations, associated ions, and their ionic ratios within the sampled brine were analyzed. The brine originating from the deep Cambrian aquifer was characterized by high salinity levels, with an average TDS value of 242 ± 11 g/L, and was dominated by a Na-Cl facies. The studied brine underwent a moderate degree of seawater evaporation, occurring between the saturation levels of gypsum and halite, accompanied by some halite dissolution. Compared to modern seawater evaporation, the depletion of Mg2+, HCO3−, and SO42− concentrations, along with the enrichment of Ca2+, Li+, K+, and Sr2+, is likely primarily attributed to water–rock interactions. These interactions include dolomitization, combination of halite dissolution, upwelling of lithium- and potassium-bearing groundwater, calcium sulfate precipitation, biological sulfate reduction (BSR), and the common ion effect within the brine system. This research offers valuable insights into the genesis of the brine within the Cambrian carbonate succession and provides theoretical backing for the development of brine resources in the future.

Studies on identification of Garudapacha - An unfamiliar raw material used in Ayurveda formulations

Introduction: The raw drugs of mineral and metallic origin are exclusively classified into different groups. There are around 70 minerals and metals described in Rasashastra. There is a rare mineral called Garudapacha used in Kerala state of India, the details of which are scarce or rather not available. It is called as veluthagarudapacha, Palgarudapacha in Malayalam language and palgarudakallu, palgaruda and garudakallu in Tamil. A brief account of shodhana and marana is also mentioned for this mineral drug. The bhasma of Garudapacha is indicated in the conditions like asthisrava (leucorrhea), netraroga (Eye disorders), asthishosha (osteoporosis) and mutrakrichra (dysuria). Materials and methods: An attempt was made in this work to collect the samples of Garudapacha from different districts of Kerala. Collected sample was examined through selected physical properties of minerals. The sample was also analysed using Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM EDS). Results: Two samples of Garudapacha could be collected one each from Palakkad and Thiruvananthapuram districts of Kerala state. On examination the sample was massive, compact, brittle, translucent to opaque, white stone, with white streak, Pearly to dull luster, flat to conchoidal fracture, 2.5 to 3.5 Hardness and 2.9 to 3 specific gravity. SEM EDS analysis showed presence of magnesium, carbon, calcium and silica. Discussion and conclusion: From the physical appearance and other mineralogical features the collected sample was identified as Magnesite a carbonate of magnesium with a chemical composition of MgCO3. It was further affirmed while the sample was subjected to instrumental analysis. There was presence of magnesium, carbon and silica among which 28.74% magnesium and 6.89 % was carbon.

Erratum to: Cryolite as a Reference Mineral of Rare Metal Mineralization: An Experimental Study

An Erratum to this paper has been published: https://doi.org/10.1134/S0016702924190030

Comprehensive research of the distribution of tellurium-bismuth mineralization in the ores of the Abyz and Maleevskoe sulfide deposits (Republic of Kazakhstan)

Abstract. Within the formations of ensimatic and ensialic island arcs in the territory of Central and Northern Kazakhstan, there are more than thirty pyrite deposits enriched in copper, lead, zinc, gold, silver and rare metal mineralization, which is still insufficiently studied. Relevance. The need to replenish information on tellurium-bismuth mineralization in ores of sulfide deposits formed in ensimatic (Abyz deposit) and ensialic (Maleevskoe deposit) island-arc systems, to establish a spatial connection of this type of mineralization with geodynamic conditions and predict the potential for their associated extraction from ore. Aim. To study and compare morphological characteristics, distribution patterns and conditions for the formation of tellurium-bismuth mineralization in ores of pyrite deposits formed in different island-arc geodynamic settings. Methods. Inductively coupled plasma mass spectrometry, mineragraphic and mineralogical analyses, scanning electron microscopy in combination with X-ray spectral microanalysis, Raman spectroscopy, thermobarogeochemical studies. Results. A comparison of the pyrite deposits of the Rudno-Altai and Chingiz-Tarbagatai island arc systems showed many similarities and differences between them. The deposits have a multi-stage formation and a similar mechanism of ore deposition with similar physicochemical conditions for the formation of tellurium-bismuth mineralization. A spatial relationship between Te-Bi mineralization and geodynamic settings was established: for deposits associated with paleooceanic structures, a predominance of the tellurium element is observed, and for continental rifts, a predominance of the bismuth element.

Dynamical and optical properties of rare phenakite mineral: A combined experimental and computational study

The electronic structure, optical and dynamical properties of the natural phenakite Be2SiO4, are studied using ab initio calculations completed by Raman spectroscopy experiments. The calculated structural properties are in excellent agreement with experimental data and are accompanied by chemical bonds analysis using Maximally Localized Wannier Functions method. The theoretical analysis of projected density of states reveals the nature of the valence band as composed by electronic states of oxygen atoms, while conducting band is composed by electronic states of Si-atoms. Using linear response method the optical properties are calculated and compared with optical properties of quartz. It was shown the similarity of rare phenakite crystal and quartz. The calculated phonon dispersion structure reveals mostly delocalized nature of phonon states with quasilocalized phonons in high-frequency range, where the most intense band in Raman spectrum is observed. The band is ambiguously assigned to the breathing mode in SiO4 tetrahedra. Basing on such peculiarity in the spectra the rapid nondestructive diagnostic method of the sample is purposed.