The unique conditions of fumaroles give rise to an exceptional diversity of mineral species due to a combination of key factors: high temperatures, atmospheric pressure, gas transport of chemical components, and the unusual geochemical setting of active volcano exhalations. Using high-temperature synthesis, we obtained single crystals of a new copper phosphate K₂CaCu₆O₂(PO₄)₄, which represents a new morphotropic modification of the fumarolic arsenate shchurovskyite, K₂CaCu₆O₂(AsO₄)₄. The K₂CaCu₆O₂(PO₄)₄ crystal structure and chemical composition were studied by single-crystal X-ray diffraction and EDS spectroscopy.

In this work, six structurally related oxysalts were grouped into the shchurovskyite family with the general formula A₂B[M₆O₂](TO₄)₄, (A is K⁺ or Rb⁺; B is Ca²⁺, Cu^2+, or K⁺; T is P⁵⁺ or As⁵⁺; and M is Cu²⁺, Cu^2+, or Al³⁺). In their structures, two-periodic blocks composed of TO₄ tetrahedra and Cu²⁺-centered polyhedra are interconnected into a heteropolyhedral framework with channels occupied by extra-framework cations. The geometric topology of the Cu-ion substructure is similar across the family. However, the anionic environment of the copper polyhedra systematically varies with symmetry changes, exhibiting a large diversity of Cu²⁺ coordination geometry. This structural flexibility arises from the Jahn–Teller effect of Cu²⁺ cations, resulting in structural rearrangement driven by temperature and compositional variations.

Calculations based on the topology of the framework channels indicate the potential for K⁺-ion migration through the K₂CaCu₆O₂(PO₄)₄ structure. Magnetic susceptibility measurements show that K₂CaCu₆O₂(PO₄)₄ undergoes a transition into a long-range ordered state with a spontaneous magnetic moment at T_C = 10 K. The fit of the χ(T) curve yields a Weiss temperature of -97.8 K, indicating dominant antiferromagnetic interactions at high temperatures. Compared to its Rb-analog (T_C = 25 K), K₂CaCu₆O₂(PO₄)₄ exhibits a lower ordering temperature and signs of magnetic frustration.

The minerals elasmochloite, Na₃Cu₆BiO₄(SO₄)₅, nabokoite, KCu₇TeO₄(SO₄)₅Cl, and atlasovite, KCu₆FeBiO₄Cl(SO₄)₅, are rare fumarolic minerals. In their crystal structures, Cu-centered polyhedra connect via edges and vertices, forming Cu–O/Cl layers with a kagome square topology. Interest in compounds featuring such architectures has grown in recent years due to the potential for realizing a quantum spin liquid state.

Given the scarcity of these minerals, analogs of elasmochloite were synthesized using a chemical vapor transport method, which simulates the fumarol conditions. It was established that, in laboratory experiments, a polymorphic variety crystallizes with the analog of the mineral, Na₃Cu₆BiO₄(SO₄)₅. Interestingly, both polymorphs belong to the same sp. gr., P2₁/n, and have similar cell parameters. Single-crystal XRD analysis revealed that the key structural difference between the polymorphs lies in the degree of distortion and a different relative arrangement of the Cu–O layers alternating with Na–O 2D fragments. In the mineral's structure, the Cu–O layers lie parallel to the monoclinic axis, whereas in the synthetic compound, they are perpendicular to the monoclinic axis. The Na–O sublattice adapts to the copper–oxygen layers, forming unique structural motifs.

In an attempt to substitute sodium ions with larger potassium ions, a new sulfate, KCu₇BiO₄(SO₄)₅, was synthesized. In its crystal structure, the magnetic subsystem of the square kagome type is decorated with additional copper cations compared to the copper subsystem in elasmochloite. The crystal structure of KCu₇BiO₄(SO₄)₅ is related to that of nabokoite, with both crystallizing in the tetragonal space group P4/ncc. The structural difference arises from the substitution of Te⁴⁺ by Bi³⁺, which is compensated by the absence of chlorine atoms in the new phase.

Magnetic susceptibility and heat capacity measurements indicate that both compounds are frustrated antiferromagnets with magnetic ordering transitions at 18 and 12 K for the Na- and K-sulfates, respectively.

Modern dolomite stromatolites were previously described in the hypersaline Petukhovskoe Soda Lake (Southwestern Siberia, Russia). Exopolysaccharides (EPSs) secreted by phototrophic communities have previously been shown to play a crucial role in their formation. In the current study, using transmission electron microscopy (TEM) with energy dispersive X-ray (EDX) spectral microanalysis, we demonstrate that clay minerals also play a significant role in the dolomitization of Ca-Mg carbonates in this lake. The lake is characterized by the development of phototrophic communities, whose huge biomass accumulates near the shoreline and gradually dries out, finally forming cavernous crusts that later become stromatolites. Three samples (S1, S2, and S3) were collected simultaneously in the littoral at different distances from the water and represent successive stages (from S1 to S3) of phototrophic biomass desiccation. TEM revealed ubiquitous clay minerals (consistent with montmorillonite composition) in all samples, which were represented by free clay particles, fine clay particles surrounding cell walls, and a completely interstitial clay-EPS matrix. Carbonate crystals of varying sizes were embedded in this matrix. IR spectroscopy indicates a transition from predominantly high-Mg calcite in S1 to a dolomite composition in S3. Consistently, TEM-EDX analysis of 130 points revealed a statistically significant decrease in the average Mg/Ca (atomic %) ratio in carbonate crystals from 4.8±2.9 (S1) to 2.8±1.2 (S2) and 1.3±0.2 (S3), while the opposite trend was observed in the Mg/Si ratio: 0.7±0.1 (S1), 1.1±0.3 (S2), and 2.0±1.2 (S3). These ratios in clays did not change significantly. The 3-5-fold excess of Mg over Ca at the analyzed points in carbonate crystals in S1 and S2 indicates that Mg may have originally been associated with clay minerals, which act as Mg donors for incorporation into the Ca-Mg carbonate crystal lattice. This research was funded by the Ministry of Science and Higher Education of the Russian Federation.

Introduction
The study of mineral–microbe interactions under extreme conditions has become a cornerstone in understanding both the origins of life and its potential beyond Earth. Minerals play a crucial role as catalytic surfaces, nutrient sources, and preservers of biosignatures. The emerging field of astrobiomineralogy integrates geochemistry, microbiology, and space sciences to explore how such processes operate from Earth’s deepest biosphere to Martian and icy moon environments.

Methods
Following PRISMA guidelines, this systematic review analyzed 180 peer-reviewed studies (2010-2025) retrieved from Scopus and Web of Science. Studies focusing on microbial colonization, biomineralization, and mineral biosignatures in extreme or simulated extraterrestrial conditions were included. Bibliometric and co-word analyses were conducted using VOSviewer.

Results
Results reveal convergent patterns between terrestrial extremophiles (e.g., cyanobacteria, Deinococcus spp.) and their mineral substrates, particularly sulfates, phyllosilicates, and iron oxides, mirroring assemblages detected on Mars and Europa. Laboratory simulations demonstrate that microbial films induce mineralogical transformations that can persist as biosignatures detectable by Raman and X-ray spectroscopy.

Conclusions
Astrobiomineralogy bridges the gap between mineral sciences and space biomedicine, elucidating how life-mineral systems respond to radiation, desiccation, and low gravity. The synthesis highlights new frontiers for planetary exploration, life detection strategies, and potential biotechnological applications of extremophilic mineral interactions in human spaceflight contexts.

Accurate identification of alteration minerals in remote polar regions remains a significant challenge due to limited field accessibility, extreme environmental conditions, and the inherent spectral complexity of exposed lithologies. Satellite-based multispectral remote sensing, particularly using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), provides an efficient means of investigating surface mineralogy. However, ASTER data are often affected by spectral redundancy, sensor noise, and overlapping absorption features that reduce mineral classification accuracy. This study introduces a hybrid dimensionality reduction and spectral classification workflow integrating Minimum Noise Fraction (MNF), Independent Component Analysis (ICA), and Spectral Angle Mapper (SAM) algorithms to enhance lithological mapping in polar environments. The workflow was applied to ASTER imagery from South Victoria Land, Antarctica, where exposure of metamorphic and hydrothermally altered rocks offers an ideal setting for method evaluation. The MNF transform was first used to suppress noise and extract high-variance components, while ICA separated independent spectral sources representing unique mineralogical signatures. Subsequently, SAM classification calibrated with United States Geological Survey (USGS) reference spectra enabled precise identification of alteration minerals. The integrated MNF–ICA–SAM approach effectively discriminated key alteration minerals including alunite, kaolinite, jarosite, chalcedony, opal, and hematite, corresponding to diagnostic Al–OH, Fe–OH, and hydrous silica absorptions across the VNIR–SWIR spectrum. Comparative analyses demonstrate that the hybrid workflow significantly improves spectral separability and classification accuracy compared with single-method techniques. These results highlight the potential of integrated spectral processing as a robust, transferable, and data-driven framework for mineral mapping in polar terrains. The proposed methodology not only enhances the geological interpretability of ASTER imagery but also establishes a foundation for future integration with hyperspectral, UAV, and machine-learning-based systems in remote and data-limited environments.

Magnesium phosphate cements (MPCs) are advanced inorganic binders gaining prominence in specialized engineering due to their rapid setting and high early strength. These properties make them exceptionally suitable for a wide range of applications beyond ordinary Portland cement (OPC), including the rapid repair of critical infrastructure, waste encapsulation, soil stabilization, and the development of refractory and corrosion-resistant coatings. While the properties of MPCs based on ammonium and potassium phosphates are well-documented, a systematic study including sodium dihydrogen phosphate is notably absent from the literature. This study presents a comprehensive comparative investigation of MPCs formulated with three different phosphate salts: potassium dihydrogen phosphate, sodium dihydrogen phosphate, or ammonium dihydrogen phosphate. The research methodology was designed to evaluate and contrast key characteristics of these cements, including their reaction kinetics, workability in the fresh state, physical characteristics, and mechanical strength in the hardened state. To elucidate the underlying mechanisms governing performance, a detailed microstructural analysis was conducted using Scanning Electron Microscopy (SEM), while the reaction products were characterized through X-ray Diffraction (XRD) and attenuated total reflectance–Fourier transform infrared (ATR-FTIR). The findings from this comparative analysis are crucial for identifying the most suitable phosphate salt for specific applications, thereby enabling the informed development and optimization of MPCs for advanced and sustainable construction. Funding: This work was supported by the Russian Science Foundation (Grant No. 24-79-10320, https://rscf.ru/en/project/24-79-10320/).

The granitic and metamorphic rocks at the Gabal Mukattab area represent the north termination of the Arabian–Nubian Shield in Sinai, which, in turn, represents the northern part of the East African Orogeny. The geochronological dynamics of the magmatism that constructed the Arabian–Nubian Shield are critical in understanding these orogenies. Our study involved dating three metamorphic rocks (846 ± 4 Ma to 818 ± 5 Ma), five calc-alkaline granitic rocks (728 ± 6 Ma to 609 ± 5 Ma), and eleven alkaline granitic rocks (678 ± 7 Ma to 555 ± 3 Ma). In the studied region, the island-arc phase of magmatism activated between 846 ± 4 Ma and 818 ± 5 Ma. The consequent syn-collisional magmatism initiated from 728 ± 6 Ma to 668 ± 5 Ma, demonstrating the temporal domination of the subduction-related compressional regime. The post-collisional magmatism started at 610 ± 5 Ma, marking the shifting of the tectonic setting from a compressional to an extensional regime. The phase of magmatism dominated until 555 ± 3 Ma in the studied region, suggesting extending the ANS magmatic activity until the Phanerozoic edge. These findings challenge the classical distinction between older magmatism, characterized by calc-alkaline granitoids, and younger magmatism, characterized by alkaline granitoids. The pre-Neoproterozoic (pre-ANS) 16 zircon xenocrystals with ages ranging between 2084 ± 9 Ma and 1094 ± 8 Ma were yielded, which might support a reworked ancient magmatic source. Seven Phanerozoic zircons showed ages between 495 ± 3 Ma and 374 ± 4 Ma, hinting at potential Ordovician–Devonian magmatic events in the region.

Efficient copper concentration via froth flotation hinges on balancing collector selectivity, frother strength, and slurry density to maximize concentrate grade at acceptable recovery and cost. This study systematically evaluates two collectors, namely K1 and K2 with a common frother across pulp densities of 34, 42, and 48% solids by mass. Batch laboratory froth flotation tests were executed under controlled hydrodynamics with rigorous, reproducible sample preparation, calibrated chemical dosing, and time-resolved concentrate pulls. Kinetics, cumulative recovery, froth stability, and grade-recovery curves were computed to quantify performance. Raising solids from 34 to 48% increased concentrate grade but depressed overall recovery, consistent with higher pulp viscosity, reduced bubble mobility, and shorter froth residence favouring selective attachment. An operational optimum emerged at 42% solids: grade improved relative to 34% with only moderate recovery loss, yielding the most cost-effective outcome when reagent consumption is included. At 34% solids, recovery was highest but concentrate grade was diluted; this regime suits scenarios prioritizing metal units. At 48% solids, selectivity improved further but recovery penalties became prohibitive. Across densities, Test 2 employing a higher-activity selective collector (K1-based) with tuned dosage outperformed alternatives, delivering superior grades at equal or better recoveries. Relative to K2, the selective regime reduced gangue entrainment and stabilized froth morphology in conjunction with the frother, enabling cleaner, faster flotation without excessive reagent addition. In conclusion, results show that (i) density is a first-order lever governing the grade recovery of copper through concentration by froth flotation; (ii) selective collector chemistry, properly dosed, shifts the frontier upward; and (iii) an operating window near 42% solids with a K1-dominant collector suite and moderated frother addition provides robust performance and lower unit reagent cost. These insights further support reagent and density set-point optimization in industrial circuits targeting higher-value concentrates with controlled chemical spend.