Minerals

30 pages, 6613 KB

Open AccessArticle

Geochemical Characterization and Process Response of Coal-Derived Post-Mining Waste to Dry Electrostatic and Magnetic Separation: Implications for REE Pre-Concentration Screening

by Paweł Friebe, Rafał Baron, Daniel Kowol, Piotr Matusiak, Olga Ziółkowska, Agata Czardybon and Karina Ignasiak

Minerals 2026, 16(6), 604; https://doi.org/10.3390/min16060604 - 4 Jun 2026

Abstract

This study compares the response of five coal-derived post-mining waste streams from Poland and the Czech Republic to dry electrostatic and magnetic separation, with emphasis on rare earth element (REE) enrichment, product yield, and material variability. The materials included dump-derived wastes and process-derived [...] Read more.

This study compares the response of five coal-derived post-mining waste streams from Poland and the Czech Republic to dry electrostatic and magnetic separation, with emphasis on rare earth element (REE) enrichment, product yield, and material variability. The materials included dump-derived wastes and process-derived streams from beneficiation operations. Electrostatic separation was performed on the <45 µm fraction, whereas magnetic separation was performed on the <3 mm fraction. Chemical composition was determined by ICP–MS, and process response was evaluated using enrichment factor (EF), product yield, and mass distribution. The ΣREE content of the feeds ranged from 109.33 to 250.54 ppm, while loss on ignition varied from 12.5% to 50.8%, confirming substantial heterogeneity. Electrostatic separation produced only moderate and material-specific enrichment, with EF ΣREE values generally close to unity and reaching a maximum of 1.26 for the Haldex K conductive product. Magnetic separation was less favourable, as most magnetic products showed ΣREE depletion or very low yields. Although the Haldex K paramagnetic product reached EF ΣREE = 1.30, its yield was only 0.2%. Overall, no tested configuration combined high REE enrichment with high product yield, indicating limited standalone beneficiation potential for the investigated materials. This study provides a comparative process-response assessment of low-grade, heterogeneous coal-derived post-mining waste streams and shows that dry electrostatic and magnetic separation can reveal material-dependent REE partitioning behaviour under laboratory conditions. Full article

(This article belongs to the Special Issue Recent Advances in Separation Techniques for Critical Minerals/Metals, Circular Economy, and Sustainability)

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19 pages, 3855 KB

Open AccessArticle

Compaction and Pressure Solution of Mixed Mineral Assemblages: Implications for Granite Fracture Sealing in the Near-Field of High-Level Radioactive Waste Repository

by Xiao Tian, Ju Wang, Jia-Wei Wang, Jing-Li Xie, Zhi-Chao Zhou and Ke Li

Minerals 2026, 16(6), 603; https://doi.org/10.3390/min16060603 - 3 Jun 2026

Abstract

The sealing behavior of fracture-filling minerals in the near-field of the deep geological repository (DGR) is critical for the safe disposal of high-level radioactive waste (HLW). In granite host rocks, natural fractures are often filled with polymineralic assemblages of calcite, quartz, and clay [...] Read more.

The sealing behavior of fracture-filling minerals in the near-field of the deep geological repository (DGR) is critical for the safe disposal of high-level radioactive waste (HLW). In granite host rocks, natural fractures are often filled with polymineralic assemblages of calcite, quartz, and clay minerals; however, their coupled compaction–pressure solution mechanisms under thermal–hydraulic–mechanical–chemical (THMC) conditions remain poorly understood. In this study, 12 fracture sealing tests were conducted on Beishan granite and its typical fracture fillings at 90 °C and 15 MPa effective stress, using different pore fluids and systematically varying grain size (75–250 μm), mineral proportions, and clay content. The results indicate that stress-assisted dissolution–precipitation of calcite in saturated CaCO₃ solution is a key process contributing to porosity reduction and chemo-mechanical densification of the fracture filling, achieving a compaction strain of 24.6%—substantially higher than those obtained in deionized water (20.6%) and under dry conditions (14.8%). Fine-grained calcite compacts more effectively than its coarse-grained counterpart, reaching a porosity as low as 4.8%; rigid quartz locally redistributes contact stress at quartz–calcite interfaces, promoting preferential deformation or dissolution of adjacent calcite, although increasing quartz abundance reduces the bulk compaction efficiency. A moderate amount of clay minerals (~20 wt%) further reduces porosity to 2.1% through lubrication and micropore filling. The study reveals a multi-stage process transitioning from mechanical compaction to chemo-mechanical sealing, and a synergistic mechanism dominated by calcite compaction–pressure solution, augmented by quartz stress redistribution and clay lubrication. These findings provide direct experimental evidence for the progressive chemo-mechanical densification of mineral-filled granite fractures, and offer quantitative constraints for long-term THMC modeling of fracture sealing behavior in HLW repositories. Full article

(This article belongs to the Special Issue Implications of THMC Processes on Long-Term Safety of Geological Disposal of Radioactive Waste, 2nd Edition)

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25 pages, 4759 KB

Open AccessArticle

Optimizing the Extraction of Rare Earth Elements from Char by Combining Physical Beneficiation and Acid Leaching in the Context of Techno-Economic Analysis

by Takumi Ichikawa, Yuki Nagase, Ryota Ishida, Fumio Sasaki and Gjergj Dodbiba

Minerals 2026, 16(6), 602; https://doi.org/10.3390/min16060602 - 3 Jun 2026

Abstract

The sustainable recovery of rare earth elements (REE-Y) from electronic waste is critical for clean-energy technologies. Yet, the commercial viability of recovering REE-Y from shredder residue char (SR-char) remains underexplored. Because recovery processes are heavily influenced by operational costs, evaluating economic feasibility alongside [...] Read more.

The sustainable recovery of rare earth elements (REE-Y) from electronic waste is critical for clean-energy technologies. Yet, the commercial viability of recovering REE-Y from shredder residue char (SR-char) remains underexplored. Because recovery processes are heavily influenced by operational costs, evaluating economic feasibility alongside metallurgical performance is essential. This study assesses a hybrid physical–chemical process using SR-char, integrating particle size classification and dry magnetic separation with optimized hydrochloric acid leaching. A first-order gross-profit screening model was also developed to evaluate the direct reagent economics of the proposed process. This framework calculates Revenue minus Acid and Neutralization Costs only, excluding capital expenditures (CapEx), labor, utilities, downstream separation losses, and the cost of the magnetic separation step. Results show that magnetic separation at 8000 G pre-concentrated REE-Y to >1800 g/t, and subsequent 10 M HCl leaching (60 °C, 3 h) yielded extractions of ~2000 g/t in the 500–1000 µm fraction. However, the profit model showed that maximizing extraction in the presence of high concentrations of other metals, such as Fe, Ca, and Al, results in net financial losses due to excessive reagent and neutralization costs. We conclude that physical pre-concentration to reduce non-target metal content is a critical commercial prerequisite. This targeted approach reframes the optimization criterion from metallurgical yield maximization to economic feasibility, providing a transferable screening framework for evaluating other complex secondary REE-Y resources where impurity-driven reagent consumption dominates process economics. Full article

(This article belongs to the Special Issue Recent Advances in Separation Techniques for Critical Minerals/Metals, Circular Economy, and Sustainability)

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21 pages, 7174 KB

Open AccessArticle

V-, Zr-, La- and Ni-Modified Dealuminated Beta Zeolites: Impact of Framework Substitution on Ni-Catalyzed CO₂ Reforming of CH₄

by Gema Gil-Muñoz and Juan Alcañiz-Monge

Minerals 2026, 16(6), 601; https://doi.org/10.3390/min16060601 - 3 Jun 2026

Abstract

This study investigates the influence of isomorphous substitution of Aluminum by V, Zr, La, and Ni in Beta zeolite frameworks used as supports for Ni-based dry reforming of methane catalysts. The research focuses on how the nature of the incorporated metal affects catalytic [...] Read more.

This study investigates the influence of isomorphous substitution of Aluminum by V, Zr, La, and Ni in Beta zeolite frameworks used as supports for Ni-based dry reforming of methane catalysts. The research focuses on how the nature of the incorporated metal affects catalytic activity and long-term stability. Catalysts were synthesized using both co-impregnation and sequential impregnation strategies. Physicochemical characterization—including gas adsorption, X-ray diffraction, transmission electron microscopy, and H₂ temperature-programmed reduction—revealed distinct structural roles for each metal. Results indicate that V primarily occupies T-vacancy sites within the dealuminated Beta framework, whereas Ni resides as charge-compensating extra-framework species or highly dispersed NiO clusters. Zr and La tend to form highly dispersed oxide species or occupy enlarged silanol nests. Notably, the addition of La₂O₃ was found to significantly enhance the long-term stability of the catalysts during the dry reforming of methane process. V-modified catalysts exhibited the highest activity but suffered from low stability; conversely, Zr incorporation offered the best overall performance, balancing high activity with enhanced stability, achieving 85% CO₂ and 75% CH₄ conversion, with no detectable carbon deposition after 98 h on stream. Full article

(This article belongs to the Special Issue Zeolite: From a Boiling Stone to the Applicable Minerals in Various Industrial Processes, 3rd Edition)

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20 pages, 7697 KB

Open AccessArticle

The Nam Xan Gold Deposit, Laos: Evidence for a Distal Intrusion-Related Gold System in the Truong Son Fold Belt

by Bounheuang Phanpasert, Ruidong Yang, Jun Chen, Patthana Bounliyong, Yifan Wen and Xinzheng Li

Minerals 2026, 16(6), 600; https://doi.org/10.3390/min16060600 - 3 Jun 2026

Abstract

The Nam Xan gold deposit is located in the central Truong Son Fold Belt of Laos. It is a newly identified distal intrusion-related gold system (IRGS) in a continental arc setting. This study uses whole-rock geochemistry, Pb and S isotope systematics, and mineral-scale [...] Read more.

The Nam Xan gold deposit is located in the central Truong Son Fold Belt of Laos. It is a newly identified distal intrusion-related gold system (IRGS) in a continental arc setting. This study uses whole-rock geochemistry, Pb and S isotope systematics, and mineral-scale analyses to trace magmatic evolution and ore-forming processes. Whole-rock data indicate that the associated intrusive suite is a calc-alkaline volcanic-arc granite (VAG) series, derived from a subduction-modified mantle source with notable crustal contributions. Pb isotopes reveal mixing arrays rather than true isochrons. Monte Carlo modeling shows binary mantle–crust mixing for igneous rocks and ternary mixing with an additional radiogenic component in ore samples, indicating enhanced fluid–rock interaction during mineralization. Sulfur isotope data show a shift from magmatic sulfur (δ³⁴S ≈ −5‰) in early skarn-stage pyrite to heavier values (δ³⁴S ≈ +6‰) in gold-bearing stages, reflecting fluid evolution driven by cooling and redox changes. Mineral chemistry data demonstrate that gold is present both as invisible gold within arsenian pyrite and as free gold in late-stage fractures. Strong correlations between Au and As, along with elevated Co/Ni ratios and enrichments in Bi, W, and F, collectively support a magmatic-hydrothermal origin. These findings define a three-stage mineralization process: an initial phase involving high-temperature magmatic fluids, a main stage characterized by sulfidation and gold deposition, and a final stage marked by polymetallic overprinting. The Nam Xan deposit is therefore interpreted as the distal manifestation of a Permian arc-related magmatic system in which magmatic fluids migrated along structural conduits and precipitated gold through interaction with carbonate host rocks. The identification of these intrusions in the distal IRGS at Nam Xan informs regional exploration models in the Truong Son Fold Belt, demonstrating the potential of carbonate platforms near Permian intrusions for future mineral exploration. Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-Ferrous and Precious Metal Deposits, 3rd Edition)

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20 pages, 2032 KB

Open AccessArticle

Hydrochemical Tracing for Solute Sources and Enrichment Mechanisms in Inland Lake Waters of the Qiangtang Plateau, Northern Tibet, China

by Yuanqing Liu, Dongguang Wen, Le Zhou, Lin Lv, Xuejun Ma, Jianhua Feng, Yanwei Guo, Jian Cao and Tao Lv

Minerals 2026, 16(6), 599; https://doi.org/10.3390/min16060599 - 3 Jun 2026

Abstract

To elucidate the solute sources, migration and enrichment mechanisms of water bodies in the endorheic lake region of the Qiangtang Plateau on the Tibetan Plateau and clarify the hydrogeochemical cycling patterns in alpine arid environments, this study focuses on two core scientific objectives: [...] Read more.

To elucidate the solute sources, migration and enrichment mechanisms of water bodies in the endorheic lake region of the Qiangtang Plateau on the Tibetan Plateau and clarify the hydrogeochemical cycling patterns in alpine arid environments, this study focuses on two core scientific objectives: quantitative identification of the multi-source contributions of aquatic solutes, and revelation of the key processes governing the enrichment of strategic elements including lithium (Li) and boron (B). To achieve these goals, we conducted systematic hydrogeological field investigations and collected 28 multi-type water samples, covering springs, rivers, thermal springs, freshwater lakes, salt lake brines, atmospheric precipitation, and glacial meltwater. The physicochemical properties, major ions, and trace elements of all samples were comprehensively analyzed. On this basis, the hydrogeochemical characteristics, evolutionary processes, and solute origins of regional waters were systematically explored. Combined with PHREEQC numerical simulation, principal component analysis (PCA), and Pearson correlation analysis, the dominant controlling factors of water geochemistry were quantified, and a conceptual hydrogeochemical evolution model was established. The results reveal a clear hydrogeochemical evolutionary gradient across the study area: water bodies evolve from low-salinity HCO₃-Ca recharge end-members and transitional HCO₃·SO₄-Ca(Mg) type water to highly mineralized Cl-Na (SO₄·Cl-Na) salt lake brines, accompanied by synchronous enrichment of Li, B, arsenic (As), and other characteristic elements. Solute accumulation in regional waters is governed by the ternary coupling effects of evaporative concentration, rock weathering and leaching, and deep geothermal fluid input, while cation exchange and mineral dissolution–precipitation reactions further modulate ionic composition and ratios. Elements including As, Li, B, and chloride (Cl⁻) exhibit conservative migration behaviors in non-hydrothermal waters, whereas thermal springs possess unique geochemical signatures driven by deep fluid recharge. PCA results indicate that evaporative concentration serves as the primary controlling factor with a contribution rate of 55.39%; rock weathering provides the basic solute load (17.09%); and the coupled processes of deep fluid mixing and carbonate precipitation regulate elemental fractionation (14.21%). These findings systematically clarify the hydrogeochemical evolution laws and multi-source coupling mechanisms of inland lake waters in the Qiangtang Plateau. Furthermore, this study establishes a conceptual framework of “multi-source recharge–water–rock interaction–evaporative concentration”, advances the understanding of alpine hydrological cycling under climate change, and provides a solid scientific foundation for hydrological cycle research and green exploration of strategic mineral resources in endorheic salt lake regions. Full article

(This article belongs to the Special Issue Challenges of Groundwater Quality Degradation in the Past Decades: Clues from Water–Minerals Interaction, 2nd Edition)

16 pages, 2879 KB

Open AccessArticle

Bulgarian Spectral Database for Painting Materials: An Open-Access Web Resource for Cultural Heritage Analysis

by Denitsa Yancheva, Simeon Stoyanov, Nikifor Haralampiev, Maria Argirova, Nikolay Lumov, Marin Rogozherov, Ekaterina Stoyanova-Dzhambazova, Vesselin Petrov and Bistra Stamboliyska

Minerals 2026, 16(6), 598; https://doi.org/10.3390/min16060598 - 3 Jun 2026

Abstract

The present work introduces the Bulgarian Spectral Database for Painting Materials, a freely accessible web-based resource containing FTIR and Raman spectra, together with complementary analytical information, for materials commonly found in Bulgarian artworks. The database encompasses a collection of over 200 reference materials [...] Read more.

The present work introduces the Bulgarian Spectral Database for Painting Materials, a freely accessible web-based resource containing FTIR and Raman spectra, together with complementary analytical information, for materials commonly found in Bulgarian artworks. The database encompasses a collection of over 200 reference materials and more than 100 entries derived from authentic samples obtained from wall paintings, dating from the 5th century BC to the 20th century. The largest section of the database consists of inorganic reference materials, including natural and synthetic mineral pigments, fillers, and additives commonly identified in historical mural paintings, complemented by organic binders and natural dyes. Reference model mixtures simulating historical painting techniques are also included. The database provides interactive visualization and downloadable spectra in plain text formats (.txt) compatible with all spectroscopic software. The integration of spectral data obtained from artworks represents a distinctive feature of the resource. The database is a practical tool for material identification, comparative studies, and conservation research in the field of cultural heritage science. It also provides a robust foundation for comparative studies and facilitates interdisciplinary research across the Balkan region and beyond. Full article

(This article belongs to the Special Issue Mineral Pigments: Properties Analysis and Applications)

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31 pages, 2932 KB

Open AccessSystematic Review

Circular Economy Approaches for Copper Recovery from Mining Waste: A Systematic Review of Leaching Technologies

by Agustín Arancibia-Zúñiga, Bastián Cornejo-Kunz, Freddy Rojas and Carlos Carlesi

Minerals 2026, 16(6), 597; https://doi.org/10.3390/min16060597 - 3 Jun 2026

Abstract

Mining activities generate large volumes of waste that pose both environmental liabilities and potential secondary resource value. A significant fraction of these materials still contains recoverable copper, making leaching a promising strategy for reprocessing and valorization, given the natural decline in ore grade. [...] Read more.

Mining activities generate large volumes of waste that pose both environmental liabilities and potential secondary resource value. A significant fraction of these materials still contains recoverable copper, making leaching a promising strategy for reprocessing and valorization, given the natural decline in ore grade. This study presents a PRISMA-based systematic review of recent literature on leaching technologies applied to mining waste, with emphasis on technical performance, environmental implications, and economic feasibility. The reviewed residues include tailings, slags, copper smelter dusts, sludges, waste rock, leaching residues, and other secondary mining and metallurgical wastes. The main leaching routes identified were acidic, biological, alkaline, and hybrid systems, including conventional H₂SO₄ leaching, pressure oxidative leaching, chloride-based systems, glycine- and ammonia-based alkaline media, organic acids, deep eutectic solvents, and biologically mediated processes. Reported Cu recoveries ranged from low values in refractory systems to near-complete extraction under optimized conditions. Overall, copper recovery was controlled primarily by the mineralogical occurrence of Cu rather than by leaching category alone. In contrast, the highest recoveries were generally associated with intensified conditions capable of overcoming sulfide- and silicate-related constraints. Environmental and circular economy benefits were frequently claimed but less often demonstrated through direct evidence, while economic assessment remained limited. Future research should better integrate mineralogical interpretation, environmental verification, and economic feasibility. Full article

(This article belongs to the Special Issue Sustainable Extraction and Reuse of Metallurgical Wastes: Towards Circular Practices)

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17 pages, 18757 KB

Open AccessArticle

Evolution of Molecular and Optical Characterization of Dissolved Organic Matter (DOM) in Deep Groundwater After Ecological Water Supplementation: Implications for Fluoride Migration

by Haigang Wang, Chunming Hao, Ruigang Han, Pengyu Luo, Beibei Chen, Lin Zhu, Chaofan Zhou, Huili Gong and Huiqing Lian

Minerals 2026, 16(6), 596; https://doi.org/10.3390/min16060596 - 3 Jun 2026

Abstract

Ecological Water Supplementation (EWS) promotes the reduction in both fluoride (F⁻) and dissolved organic matter (DOM) concentration in deep groundwater. However, investigations on the optical properties and molecular signatures of DOM associated with F⁻ concentration variation have rarely been carried [...] Read more.

Ecological Water Supplementation (EWS) promotes the reduction in both fluoride (F⁻) and dissolved organic matter (DOM) concentration in deep groundwater. However, investigations on the optical properties and molecular signatures of DOM associated with F⁻ concentration variation have rarely been carried out. In our study, deep groundwater samples before and after EWS were collected form Nanpi County, North China, to evaluate the implications for F⁻ migration. The results showed that the decrease in F⁻ concentration was closely related to the variation in molecular and optical signatures of deep groundwater DOM during the EWS process. Priority degradation of unsaturated and biodegradable compounds with higher H/C ratio resulted in aromatic DOM with higher HIX and SUVA₂₅₄ value enrichment in deep groundwater after EWS. Weaker competitive effects, calcite and dolomite precipitate, and enhancing F-bearing minerals dissolution under decreasing microbial metabolic activity contributed to F⁻ depletion in deep groundwater. The findings establish an association between the variation in DOM molecular and optical signatures and F⁻ concentration, and provide a new mechanism for investigating DOM cycling under the influence of F⁻ in deep groundwater. Full article

(This article belongs to the Special Issue Challenges of Groundwater Quality Degradation in the Past Decades: Clues from Water–Minerals Interaction, 2nd Edition)

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5 pages, 210 KB

Open AccessEditorial

Editorial for Special Issue “New Discovery and Exploration Methods of Porphyry and Epithermal Mineral Deposits”

by Chao Yang, Yiwei Peng and Gangyang Zhang

Minerals 2026, 16(6), 595; https://doi.org/10.3390/min16060595 - 2 Jun 2026

Abstract

Porphyry deposits and their genetically and spatially associated epithermal deposits constitute one of the most economically significant mineral systems, attracting extensive attention from both industrial practitioners and academic researchers [...] Full article

(This article belongs to the Special Issue New Discovery and Exploration Methods of Porphyry and Epithermal Mineral Deposits)

16 pages, 87145 KB

Open AccessArticle

Evaluating Inter-Species Interaction in the Differential Settling of Binary Particle Suspensions

by Yuan Li and Luis Tejada Arata

Minerals 2026, 16(6), 594; https://doi.org/10.3390/min16060594 - 2 Jun 2026

Abstract

This study investigates the differential settling behavior of binary particle suspensions through a combination of theoretical modeling and batch settling experiments. A classical zone-formation differential settling model is adopted, and a comprehensive experimental program is designed to generate data for model evaluation. Batch [...] Read more.

This study investigates the differential settling behavior of binary particle suspensions through a combination of theoretical modeling and batch settling experiments. A classical zone-formation differential settling model is adopted, and a comprehensive experimental program is designed to generate data for model evaluation. Batch settling tests conducted using fine copper tailings and coarse silica sands show that distinct settling zones can be identified, and the solids’ concentrations of the particle species are consistent with theoretical predictions. However, the behavior within the sediment region differs from model assumptions, as a range of solids’ concentrations is observed, suggesting the presence of a transition zone rather than a sharp transition from the hindered settling region to a sediment with maximum solids’ concentration. Experimental observations of the sediment boundary also reveal a discrepancy between theoretical predictions and measured propagation velocities. This discrepancy is attributed to inter-species interactions arising from differential settling velocities, which are not accounted for in conventional models. The results highlight the limitations of widely used differential settling models and emphasize the importance of incorporating species–species interactions and transition zone behavior to improve the prediction of settling behavior in multi-species suspensions. Full article

(This article belongs to the Special Issue Advances in Mine Backfilling Technology and Materials, 2nd Edition)

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19 pages, 30090 KB

Open AccessArticle

Seismic Imaging of the Crust and Upper Mantle Beneath Chinese Fujian Province and Its Implications for Deep Mineralization

by Yundi Song, Xiaolong He, Guoming Jiang, Dapeng Zhao and Guibin Zhang

Minerals 2026, 16(6), 593; https://doi.org/10.3390/min16060593 - 1 Jun 2026

Abstract

Fujian Province is located in the southeast coastal region of Mainland China and belongs to the Cathaysia Block (CB). Since the Neoproterozoic, this region has experienced multi-stage tectonic activities, which have formed extensive metallogenic belts, such as the Wuyishan and Nanling metallogenic belts. [...] Read more.

Fujian Province is located in the southeast coastal region of Mainland China and belongs to the Cathaysia Block (CB). Since the Neoproterozoic, this region has experienced multi-stage tectonic activities, which have formed extensive metallogenic belts, such as the Wuyishan and Nanling metallogenic belts. To clarify deep geodynamic processes and deep metallogenic mechanisms, we determine a high-resolution three-dimensional (3-D) velocity model of the crust and upper mantle beneath the Fujian region. Two datasets are collected for the tomographic inversion. One dataset includes 70,330 P-wave and 87,057 S-wave arrival times from 6206 local earthquakes. The other dataset includes 13,714 P-wave relative travel-time residuals from 812 teleseismic events. Our tomography reveals significant low-velocity (low-V) anomalies in the upper mantle down to 500 km depth, which may represent hot ad wet upwelling flows from the mantle transition zone. We also find some low-V and high-Vp/Vs anomalies in the crust beneath major faults and the coastal area of Fujian, which are interpreted as magmatic channels. Combining with previous geological, geochemical, and geophysical results, we consider that the subduction of the Paleo-Pacific Plate in the Late Mesozoic played a crucial role in the formation of ore deposits. We propose a geodynamic model of the deep mineralization in Fujian, in which upwelling mantle flow underplated the crust and intruded into the crust along fault zones. This geodynamic model also has certain significance for the deep mineralization mechanisms of the CB and the Lower Yangtze Block. Full article

(This article belongs to the Special Issue Continental Crust Evolution in Collisional and Accretionary Orogens: Petrological, Tectonic and Metallogenic Implications)

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26 pages, 9013 KB

Open AccessArticle

Development of Five Stream Sediment Certified Reference Materials for Geochemical Surveys in Arid Desert Areas of North China

by Rong Yang, Hanjiang Pan, Mei Liu and Xue Gu

Minerals 2026, 16(6), 592; https://doi.org/10.3390/min16060592 - 1 Jun 2026

Abstract

Certified reference materials (CRMs) play a pivotal yet frequently overlooked function in mineral exploration. Effective exploration requires CRMs that closely match the geological background. With the full launch of a new round of prospecting strategic breakthrough actions, large-scale regional geochemical surveys will be [...] Read more.

Certified reference materials (CRMs) play a pivotal yet frequently overlooked function in mineral exploration. Effective exploration requires CRMs that closely match the geological background. With the full launch of a new round of prospecting strategic breakthrough actions, large-scale regional geochemical surveys will be conducted around the main metallogenic zones in China. Currently, there is a notable shortage of CRMs specifically designed for the arid desert regions of northern China, which have huge mineralization potential. To address this gap and meet analysis and testing needs for stream sediment samples, five stream sediment CRMs have been developed for these arid desert areas. These CRMs represent diverse geological settings: a regional background area, a Ni-polymetallic mining area, a Cu mining area, a Cu-Pb-Zn polymetallic mining area, and a Cu-Fe mining area. The development process strictly followed the requirements outlined in the ISO series of international standards for CRMs. The candidate materials were prepared in accordance with these standards, involving procedures such as impurity removal, drying, multi-stage milling, and homogenization prior to packaging. Homogeneity and stability were evaluated using 30 randomly selected units per candidate, and the results demonstrated excellent performance in both aspects. For characterization, 13 authoritative laboratories collaborated to determine the concentrations of 73 components using validated measurement techniques. Through statistical measurement and rigorous uncertainty assessment, it was confirmed that these materials meet all requirements for CRMs. These new CRMs are recommended for property value assignment, instrument calibration, quality control, and proficiency testing in regional geochemical surveys and mineral exploration. Full article

(This article belongs to the Special Issue Geochemical Exploration for Critical Mineral Resources, 2nd Edition)

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22 pages, 2768 KB

Open AccessArticle

Elemental Geochemistry of Float-Sink Products from Late Paleozoic Coals with Different Ranks: Implications for Clean Utilization and Resource Potential

by Dongna Liu, Wenhui Yi, Fenghua Zhao and Bijiang Xue

Minerals 2026, 16(6), 591; https://doi.org/10.3390/min16060591 - 1 Jun 2026

Abstract

Coal rank exerts a fundamental control on the distribution of elements during density-based separation, yet this influence remains poorly understood. The primary objective of this study is to elucidate how coal rank governs the enrichment and partitioning of major, trace, and rare earth [...] Read more.

Coal rank exerts a fundamental control on the distribution of elements during density-based separation, yet this influence remains poorly understood. The primary objective of this study is to elucidate how coal rank governs the enrichment and partitioning of major, trace, and rare earth elements (REY) in float–sink products, and to assess the implications for clean coal utilization and critical metal recovery. To achieve this, three Late Paleozoic bituminous coals of different ranks from Shanxi Province, China, were subjected to density fractionation (1.3–1.8 g/cm³) combined with proximate and ultimate analyses, X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD), and coal petrography. The results show that coal rank fundamentally governs element distribution and enrichment patterns. With increasing rank, the dominant inorganic minerals shift from clay minerals to carbonates, leading to pronounced differentiation in elemental affinities. In medium- to high-rank bituminous coals, chalcophile elements (e.g., As, Mo, Tl) associated with sulfides are significantly enriched in high-density fractions, whereas in high-rank bituminous coals, carbonate-related elements (e.g., Sr, Ca, Mg) show marked enrichment. Rare earth elements are primarily hosted in clay and phosphate minerals. Light rare earth elements dominate in medium- to high-rank coals, while middle rare earth elements increase in high-rank coals due to carbonate influence. Density-based separation effectively concentrates hazardous elements (e.g., As, Pb, Cd) in high-density tailings, demonstrating substantial potential for mitigating environmental risks. Meanwhile, critical metals such as lithium (Li), strontium (Sr), and REY are enriched in medium- to high-density products, with Li hosted in clay minerals and Sr strongly enriched in carbonate-rich high-rank coal (up to 1525 μg/g), indicating recoverable resources from coal processing wastes. Full article

(This article belongs to the Special Issue Advanced Coal Processing: Comminution, Concentration, Desulphurization and Process Optimization)

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19 pages, 6894 KB

Open AccessArticle

The Provenance of Fine-Grained Sediments from the Central Basin Fault Rift, West Philippine Sea: Insights into the Input of Asian Aeolian Dust

by Zi-Shan Zhang, Chong-Jin Pang and Bryan Krapež

Minerals 2026, 16(6), 590; https://doi.org/10.3390/min16060590 - 1 Jun 2026

Abstract

The Central Basin Fault Rift (CBFR) is a key area for studying deep-sea sedimentation and paleoclimate, yet its sedimentary process and provenance and their links to geological and climatic changes remain poorly understood. This study therefore conducted systematically sedimentological, mineralogical and geochemical analyses [...] Read more.

The Central Basin Fault Rift (CBFR) is a key area for studying deep-sea sedimentation and paleoclimate, yet its sedimentary process and provenance and their links to geological and climatic changes remain poorly understood. This study therefore conducted systematically sedimentological, mineralogical and geochemical analyses of sediments in core ZK06 from the CBFR to address the above question. The results show that the sediments are dominated by silt and clay, with multiple graded rhythms related to gravity flows. Provenance analysis shows that the sediments are composed primarily of proximal andesitic volcaniclastic detritus, with additional Asian aeolian dust and minor authigenic components. It is recognized that the proportion of Asian aeolian dust increases from the lower to medium part of the sediment sequence but decreases in the upper part, which may correspond to the input history of Asian aeolian dust in the West Philippine Basin during the late Pleistocene to Holocene. This study therefore provides not only new insights into sedimentary processes and the provenance of sediments but also the input history of the Asian aeolian dust in central CBFR. Full article

(This article belongs to the Special Issue Geochronology, Geochemistry, and Tectonic Significance of Pyroclastic Rocks)

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24 pages, 9760 KB

Open AccessArticle

Ore Genesis of the Dajing Cu–Sn Polymetallic Deposit in the Southern Great Xing’an Range, NE China: Constraints from In Situ S-Pb Isotope and Electron-Microprobe Data of Sulfides

by Yanping He, Zhenjun Sun, Wentan Xu, Henan Yu, Yunsheng Ren, Zhenzhen Li, Mengfan Guan and Zhiwen Zhen

Minerals 2026, 16(6), 589; https://doi.org/10.3390/min16060589 - 1 Jun 2026

Abstract

The Dajing giant Cu–Sn polymetallic deposit is located in the Cu–Sn–Ag–Pb–Zn polymetallic belt of the southern Great Xing’an Range, NE China. Research on its ore genesis is of great significance for understanding Sn polymetallic mineralization in this region. In this study, pyrite, arsenopyrite, [...] Read more.

The Dajing giant Cu–Sn polymetallic deposit is located in the Cu–Sn–Ag–Pb–Zn polymetallic belt of the southern Great Xing’an Range, NE China. Research on its ore genesis is of great significance for understanding Sn polymetallic mineralization in this region. In this study, pyrite, arsenopyrite, and sphalerite were analyzed by electron-microprobe analysis (EMPA) and in situ S–Pb isotope analysis. Previously published fluid-inclusion microthermometric and H–O isotope data were also incorporated to constrain fluid evolution and ore genesis. Both in situ S and Pb isotopic compositions fall within short ranges. The δ³⁴S values suggest a sulfur reservoir with possible magmatic contribution, whereas Pb isotopes indicate a mainly crustal Pb signature in an orogenic setting. Arsenopyrite records variations in As, S, Fe, and Co contents from core to rim. The Co-rich core shows Co enrichment accompanied by Fe depletion, consistent with Co-for-Fe isomorphous substitution. These features indicate changes in local fluid chemistry during arsenopyrite growth. Sulfur isotope geothermometry based on coexisting late-stage pyrite–sphalerite pairs yields 118–233 °C, with an average of 159 ± 49 °C, indicating medium- to low-temperature hydrothermal activity during the late sulfide stage. The Dajing deposit is interpreted as a fault-controlled hydrothermal vein-type Cu–Sn polymetallic deposit formed in a Late Jurassic extensional setting. Ore precipitation was likely promoted by cooling during upward fluid migration away from the magmatic heat source, pressure release, meteoric-water mixing, and fluid–rock interaction with granitic rocks and Linxi Formation wall rocks. This study provides mineral-scale constraints on fluid evolution and ore genesis in the Great Xing’an metallogenic belt. Full article

(This article belongs to the Section Mineral Deposits)

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35 pages, 5619 KB

Open AccessReview

A Review of Urease-Based Biomineralization: MICP and EICP

by Jifan Liu, Yingying Hu, Jianjun Shen, Weitao Liu and Ying Xu

Minerals 2026, 16(6), 588; https://doi.org/10.3390/min16060588 - 1 Jun 2026

Abstract

Microbial-induced calcite precipitation (MICP) and enzyme-induced calcite precipitation (EICP) have emerged as research hotspots in recent years at the intersection of geotechnical engineering, environmental engineering, and materials engineering. Compared with traditional grouting reinforcement and repair methods, these methods exhibit greater environmental benignity, higher [...] Read more.

Microbial-induced calcite precipitation (MICP) and enzyme-induced calcite precipitation (EICP) have emerged as research hotspots in recent years at the intersection of geotechnical engineering, environmental engineering, and materials engineering. Compared with traditional grouting reinforcement and repair methods, these methods exhibit greater environmental benignity, higher calcium carbonate precipitation yield, and more significant improvement in mechanical properties of repaired materials. The urease activity in the urease-based MICP and EICP techniques lies at the core of rock fracture repair, soil reinforcement, and concrete crack remediation. This paper presents a systematic review of urease-based MICP and EICP repair technologies, focusing on repair principles, environmental influencing factors, research methods, and application approaches, including microbial cultivation, enzyme activity determination, preparation of cementing solutions, selection of carriers, injection methods, and repair cycles. It also compares the advantages and disadvantages of MICP and EICP. This review clarifies the intrinsic similarities and differences between the two technologies in mineralization mechanism, crystal characteristics and engineering applicability, and constructs a complete technical system of urease-based biomineralization. Additionally, this paper discusses current macroscopic and microscopic evaluation methods for biomineralization repair effects, synthesizes existing mineralization repair systems, and assesses the challenges of self-healing biomaterials, including long-term microbial durability, repair strength stability, and the overall cost of widespread application. It includes long-term microbial durability, repair strength stability, enzyme activity retention, and the overall cost of widespread application, which are key issues to be solved for engineering implementation. The aim of this study is to provide a theoretical and practical reference for the theoretical improvement and engineering application of EICP and MICP technologies. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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21 pages, 12931 KB

Open AccessArticle

Geochronology, Geochemistry, and Petrogenesis of Nepheline Syenites from Granite Mountain, Arkansas Alkaline Province, USA

by Mackenzie Benton and Haibo Zou

Minerals 2026, 16(6), 587; https://doi.org/10.3390/min16060587 - 1 Jun 2026

Abstract

The Arkansas Alkaline Province (AAP) is made up of intrusive bodies throughout central Arkansas, one of which is a nepheline syenite body called Granite Mountain. The crystallization age and origin of nepheline syenites from Granite Mountain are still uncertain, in part due to [...] Read more.

The Arkansas Alkaline Province (AAP) is made up of intrusive bodies throughout central Arkansas, one of which is a nepheline syenite body called Granite Mountain. The crystallization age and origin of nepheline syenites from Granite Mountain are still uncertain, in part due to the rarity of zircon grains in silica-undersaturated rocks, such as nepheline syenite. This study reports new zircon U-Pb ages and trace element contents from three nepheline syenite samples from Granite Mountain. The zircon U-Pb ages of these samples are 90.4 ± 0.6 Ma, reflecting the crystallization age for nepheline syenite from Granite Mountain. Zircon rare-earth element patterns display remarkable positive Eu anomalies, indicative of their mantle affinity. Whole-rock geochemical characteristics include depleted Nd–Hf isotopic compositions, high ²⁰⁶Pb/²⁰⁴Pb ratios (19.5), and positive Nb-Ta anomalies. Their Sr-Nd-Pb-Hf isotopic compositions and trace element ratios display characteristics of ocean island basalts (OIBs). The probable magmatic source of these samples is a mixture of enriched mantle 2 (EM2) and high ²³⁸U/²⁰⁴Pb (HIMU). Taken together, the geochemical data, in particular, the HIMU signature, suggest that the Granite Mountain nepheline syenites formed within a mantle plume (likely Bermuda) tectonic setting at 90.4 Ma, although a rifting origin cannot be ruled out. Full article

(This article belongs to the Special Issue Igneous Rocks as Archives of Earth's Geological History: Magma Processes and Continental Crust Evolution)

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25 pages, 17224 KB

Open AccessArticle

Mesozoic Dykes in the Xingcheng Area, Western Liaoning Province, NE China: Phases, Petrogenesis, and Tectonic Setting

by Zhixiong Tan, Deyou Sun, Wenqing Li, Weimin Li, Yujie Hao, Jun Gou and Changqing Zheng

Minerals 2026, 16(6), 586; https://doi.org/10.3390/min16060586 - 30 May 2026

Abstract

The Mesozoic dykes in the Xingcheng area of western Liaoning Province in China were investigated through an integrated study involving zircon U–Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic compositions to elucidate their emplacement phases, petrogenesis, and tectonic setting. The dykes are classified [...] Read more.

The Mesozoic dykes in the Xingcheng area of western Liaoning Province in China were investigated through an integrated study involving zircon U–Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic compositions to elucidate their emplacement phases, petrogenesis, and tectonic setting. The dykes are classified into two groups: felsic (granite porphyry, granite aplite) and mafic (diabase, lamprophyre). Emplacement occurred in four discrete phases: Late Triassic (229–212 Ma), Early Jurassic (ca. 179 Ma), Late Jurassic (162–152 Ma), and Early Cretaceous (133–102 Ma). The felsic dykes are characterized by high SiO₂ and alkali contents, low TFeO and MgO abundances, and belong to the high-K calc-alkaline I-type granite series. The mafic dykes exhibit low SiO₂, elevated MgO, and high Na₂O contents, displaying both alkaline and calc-alkaline affinities. Both dyke suites are consistently enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and depleted in heavy rare earth elements (HREEs) and high field-strength elements (HFSEs). Zircon ε_Hf(t) values for the felsic dykes range from −22.3 to −7.4, corresponding to two-stage model ages (T_DM2) of 2613–1729 Ma, indicating derivation from partial melting of Neoarchean to Paleoproterozoic crustal material. Late Jurassic mafic dykes yield ε_Hf(t) values between −27.8 and −20.2, consistent with an origin from partial melting of enriched lithospheric mantle. In contrast, Early Cretaceous mafic dykes display a bimodal ε_Hf(t) distribution (−12.9 to −9.5 and +4.3 to +8.4), suggesting a predominant enriched mantle source with variable inputs from depleted mantle components. Integrated with regional tectonic reconstructions, the data indicate that the Xingcheng area evolved within a post-collisional extensional regime following the amalgamation of the North China Craton and the Central Asian Orogenic Belt during the Late Triassic. The Jurassic magmatic pulses are attributed to an active continental margin setting associated with subduction of the Paleo-Pacific Plate, whereas the Early Cretaceous phase reflects regional extension triggered by rollback of the subducting Paleo-Pacific slab. Full article

(This article belongs to the Special Issue Advances in Granite Geochronology and Geochemistry)

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