Minerals

20 pages, 6028 KB

Open AccessArticle

Grain-Scale Heterogeneity, Fracture Competition, and Non-Planar Propagation in Crystalline Rocks: Insights from a Hydro-Mechanical Phase-Field Model

by Gen Zhang, Cheng Zhao, Zejun Tian, Jinquan Xing, Jialun Niu, Zhaosen Wang and Wenkang Yu

Minerals 2026, 16(3), 339; https://doi.org/10.3390/min16030339 - 23 Mar 2026

Viewed by 515

Abstract

Grain-scale heterogeneity strongly influences hydraulic fracture initiation and trajectory in crystalline rocks, yet its contributions to non-planar growth and the interaction of multiple nearby cracks remain insufficiently quantified. To address this gap, we perform numerical experiments on a model containing two parallel pre-existing [...] Read more.

Grain-scale heterogeneity strongly influences hydraulic fracture initiation and trajectory in crystalline rocks, yet its contributions to non-planar growth and the interaction of multiple nearby cracks remain insufficiently quantified. To address this gap, we perform numerical experiments on a model containing two parallel pre-existing cracks using a hydro-mechanical phase-field framework, systematically quantifying how mineral distribution and axial compression govern non-planar hydraulic fracture growth and inter-fracture competition. The results demonstrate that mineral distribution is the primary driver of fracture complexity. Even within the same Voronoi tessellation, redistributing minerals alone yields markedly different trajectories, deflections, branching patterns, and final morphologies. Furthermore, non-planar growth follows a stepwise, energy-threshold-driven mechanism. When cracks penetrate strong grains or undergo large-angle deflections, propagation is impeded, and injection pressure builds up. Once a critical energy threshold is reached, accumulated energy is rapidly released along the path of minimum incremental energy, manifested as abrupt pressure drops and rapid crack advance. Additionally, the two nearby fractures exhibit strong mechanical competition. Despite negligible hydraulic interference in low-permeability granite, early growth of one fracture redistributes stresses and suppresses the driving force of the other, resulting in asymmetric development. Finally, axial compression primarily governs the overall propagation orientation and influences local failure modes but has a limited effect on peak pressure relative to mineral distribution. Full article

(This article belongs to the Topic Complex Rock Mechanics Problems and Solutions, 2nd Edition)

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19 pages, 4742 KB

Open AccessEditor’s ChoiceArticle

Monazite U-Pb Chronology, Pyrite Rb-Sr Chronology and Isotope Geochemistry of the Xidouya Gold Deposit in the Jiaodong Peninsula, Eastern China: Constraints on the Timing and Process of Mineralization

by Faqiang Zhao, Zhimin Li, Peng Guo, Tongliang Tian, Bin Li, Jiabin Yu, Dongyue Li, Pengpeng Zhang and Jiepeng Tian

Minerals 2026, 16(3), 338; https://doi.org/10.3390/min16030338 - 23 Mar 2026

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Abstract

The Jiaodong gold concentration area, one of the most important gold metallogenic belts in China, has long been the focus of contentious debates regarding the genetic mechanisms and timing of gold mineralization. This study presents the new monazite U-Pb and pyrite Rb-Sr isotopic [...] Read more.

The Jiaodong gold concentration area, one of the most important gold metallogenic belts in China, has long been the focus of contentious debates regarding the genetic mechanisms and timing of gold mineralization. This study presents the new monazite U-Pb and pyrite Rb-Sr isotopic chronology data for the No. I ore zone of the Xidouya gold deposit, integrated with H-O-S isotopic geochemical analyses, to systematically investigate the mineralization age, ore-forming fluid sources and material provenance of the deposit. The main mineralization age of the deposit is constrained to 117 Ma, which is highly consistent with the regional mineralization peak of 120 ± 5 Ma in the Jiaodong gold concentration area. The δD values of the fluids range from −88.0‰ to −75.0‰ (mean = −82.6‰), while the δ¹⁸O_H₂O values are calculated to be between 4.6‰ and 6.1‰. H-O isotopic data indicate that the ore-forming fluids of the Xidouya gold deposit originated from a mixed magmatic and meteoric source. As mineralization progressed from Stage I through Stage III, there was a detectable trend of increasing meteoric water involvement and a general decrease in δD and δ¹⁸O_H₂O values. This signature indicates that the initial mineralizing system was dominated by primary magmatic water which subsequently underwent significant water–rock interaction with Early Cretaceous granitic bodies and progressive dilution by meteoric fluids in an open tectonic environment. Furthermore, sulfur isotopes (average δ³⁴S = +7.43‰) and the initial strontium isotope ratio (⁸⁷Sr/⁸⁶Sr = 0.71012) support a mixed-source model for the ore-forming materials, likely dominated by the anatexis of ancient crust with potential minor mantle-derived contributions. During the Early Cretaceous, lithospheric thinning and extension in the North China Craton (NCC) triggered large-scale magmatism and mineralization. The Xidouya gold deposit is a direct product of these regional tectono-magmatic-mineralizing events. This study provides new high-precision isotopic dating data for the Xidouya gold deposit, clarifies the evolutionary history of ore-forming fluids and the supply mechanism of ore-forming materials, and provides important theoretical insights and practical references for gold prospecting and exploration in the eastern part of the Jiaodong gold concentration area. Full article

(This article belongs to the Section Mineral Geochemistry and Geochronology)

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28 pages, 4795 KB

Open AccessReview

Earliest Evolved Rocks: A Solar System Perspective

by Sheng Shang

Minerals 2026, 16(3), 337; https://doi.org/10.3390/min16030337 - 22 Mar 2026

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Abstract

Granitic rocks dominate Earth’s continental crust, yet the Hadean record is severely limited. Extraterrestrial evolved lithologies, crystallized under predominantly anhydrous, plate tectonics-free conditions analogous to those of early Earth, provide valuable analogues. This review synthesizes lunar, asteroidal, Martian, and candidate Venus/Mercury data, revealing [...] Read more.

Granitic rocks dominate Earth’s continental crust, yet the Hadean record is severely limited. Extraterrestrial evolved lithologies, crystallized under predominantly anhydrous, plate tectonics-free conditions analogous to those of early Earth, provide valuable analogues. This review synthesizes lunar, asteroidal, Martian, and candidate Venus/Mercury data, revealing that partial melting of mafic protoliths, not fractional crystallization or silicate liquid immiscibility, represents the dominant formation mechanism. Granitic magmatism persisted episodically from merely 1.11 Myr after Solar System formation through at least 3.87 Ga, with estimated abundances of 0.2%–2% representing a conservative lower limit. These findings imply that Hadean Earth possessed the thermal and compositional prerequisites for analogous magmatism, suggesting that substantial felsic material may have been present, though quantitative estimates remain unwarranted given current data limitations. By establishing a comparative planetary framework, this study illuminates pathways for reconstructing Hadean crustal differential processes, highlighting priorities for future exploration missions targeting cryptic silicic reservoirs, particularly deep-crustal exposures in large lunar impact basins and in situ characterization of Venusian highland terrains. Full article

(This article belongs to the Section Mineralogy Beyond Earth)

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15 pages, 3052 KB

Open AccessArticle

The Effect of DFT and DFT + U Calculations on the Crystal Structure of the Diopside (CaMgSi₂O₆)–Hedenbergite (CaFeSi₂O₆) Solid Solution Series

by Qian Wang, Yang Zhao, Yongbing Li, Yonghui Li and Shanqi Liu

Minerals 2026, 16(3), 336; https://doi.org/10.3390/min16030336 - 22 Mar 2026

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Abstract

Diopside–hedenbergite solid solution is the most common clinopyroxene end-member combination in mafic and ultramafic igneous rocks. The crystal structure variety caused by Mg-Fe isomorphous substitution can indicate geological processes such as Mg-Fe isotope fractionation. To explore the effect of Hubbard U correction and [...] Read more.

Diopside–hedenbergite solid solution is the most common clinopyroxene end-member combination in mafic and ultramafic igneous rocks. The crystal structure variety caused by Mg-Fe isomorphous substitution can indicate geological processes such as Mg-Fe isotope fractionation. To explore the effect of Hubbard U correction and Fe content on iron-bearing clinopyroxene structures, we employed GGA and GGA + U to study the lattice constants, unit-cell volume, and average Fe-O bond length of the diopside–hedenbergite solid solution series. On the whole, the results by GGA + U are the increase in lattice constant a (from 9.910 Å to 10.030 Å) and volume (from 456.656 Å³ to 464.640 Å³), the decrease in β angle (from 106.121°to 105.320°), and a slight variation in the lattice constant b (from 9.007 Å to 9.010 Å) with increasing Fe content, which is a better match with the experiment than those by GGA. The average Fe-O bond lengths and polyhedral volumes calculated by GGA and GGA + U both increase with increasing Fe content. The Hubbard U correction significantly affects the lattice constants and unite-cell volume at medium-high Fe content (Fe/(Ca+ Mg + Fe) > 2/8), the Fe-O bond at low Fe content (Fe/(Ca+ Mg + Fe) < 1/8), the bond angle variance, distortion index and quadratic elongation at relatively medium Fe content (1/8 ≤ Fe/(Ca+ Mg + Fe) ≤ 5/16). This study verifies the effectiveness of U-value correction on iron-bearing clinopyroxene and provides a theoretical basis for understanding its structural evolution. Full article

(This article belongs to the Section Crystallography and Physical Chemistry of Minerals & Nanominerals)

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37 pages, 33342 KB

Open AccessArticle

In Situ Analyses of Sulphides from the Tomingley Gold Project, Central-West NSW, Australia: Pathfinder Textures and Trace Elements

by Muhammad Fariz Bin Md Nasir, Indrani Mukherjee, Alexander Cherry, Ian Graham, Karen Privat and Ivan Belousov

Minerals 2026, 16(3), 335; https://doi.org/10.3390/min16030335 - 21 Mar 2026

Viewed by 705

Abstract

This study investigated sulphide textures and trace element chemistry from the Tomingley Gold Project (TGP) region of Central-West NSW, eastern Australia, using in situ techniques. In particular, the study focused on pyrite and arsenopyrite to gain insights into ore-forming processes and determine which [...] Read more.

This study investigated sulphide textures and trace element chemistry from the Tomingley Gold Project (TGP) region of Central-West NSW, eastern Australia, using in situ techniques. In particular, the study focused on pyrite and arsenopyrite to gain insights into ore-forming processes and determine which trace elements within these minerals can be used as potential pathfinder elements for mineral exploration in the TGP. A total of 41 drill core samples from a variety of lithologies (volcaniclastic, monzodiorite, graphitic siltstone, dacite, andesite) were described and analysed using reflected light microscopy, high-resolution microscopy (via Scanning Electron Microscope or SEM), elemental mapping (via Electron Probe Micro Analysis or EPMA) and targeted trace element analysis of sulphide grains (via Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry or LA-ICP-MS). Findings show that pyrite and arsenopyrite are the major sulphides that host fracture-fill/inclusions of native gold and ‘invisible gold’. Pyrite rich in groundmass inclusions should be evaluated due to their characteristic high concentrations of both As and Au. Pyrite trace element chemistry (Sn, Bi, W, Sb, Au and Se) was able to delineate mineralised from unmineralised samples in volcaniclastics, graphitic siltstones and andesites but was much more challenging for lithologies like dacites and monzodiorites. The study also found that Au may have been introduced into the system earlier and existed as ‘invisible gold’ in earlier generations of pyrite. This study highlighted the utility of in situ techniques to discriminate mineralised signatures from unmineralised samples, and this has proven to be far more effective compared to whole-rock techniques, emphasising the benefits of such datasets in mineral exploration. Full article

(This article belongs to the Special Issue Gold Deposits: From Primary to Placers and Tailings After Mining)

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28 pages, 14728 KB

Open AccessArticle

Decoding the Middle Tonian Tectonic Evolution of the Jiangnan Orogen, South China: Integrated Constraints from Volcano-Sedimentary and Magmatic Records of the Fanjingshan Region

by Yaran Dai, Jiawei Zhang, Taiping Ye, Tingting Zhang, Jianshu Chen and Lei Shi

Minerals 2026, 16(3), 334; https://doi.org/10.3390/min16030334 - 21 Mar 2026

Viewed by 639

Abstract

The Middle Tonian tectonic setting of the Jiangnan Orogen, South China, remains intensely debated, and is centered on two competing models: subduction–collision versus mantle plume. This study addresses this critical knowledge gap through an integrated, multi-proxy investigation of the Middle Tonian Fanjingshan Group. [...] Read more.

The Middle Tonian tectonic setting of the Jiangnan Orogen, South China, remains intensely debated, and is centered on two competing models: subduction–collision versus mantle plume. This study addresses this critical knowledge gap through an integrated, multi-proxy investigation of the Middle Tonian Fanjingshan Group. This region preserves a continuous volcano-sedimentary and magmatic record, offering key insights into the orogen’s full lifecycle. To test these hypotheses, we employed a synthesis of geological survey, sediment provenance analysis, detrital zircon U-Pb geochronology of clastic rocks to determine sediment provenance and basin evolution, and petrogenetic study of coeval magmatic suites (pillow lava, mafic–ultramafic sills, and granitoids) to evaluate their magmatic processes and tectonic setting. Analysis of 1736 detrital zircon U-Pb ages from Middle Tonian strata reveals a four-stage provenance evolution: (1) SW Yangtze sources in a passive margin basin before 870 Ma; (2) bidirectional sources in an 870–835 Ma arc-derived basin; (3) syn-collisional detritus during 835–820 Ma amalgamation; and (4) post-collisional and northern Yangtze inputs in an 800 Ma rifting basin. Geochemical data from ~845–840 Ma basalts and coeval sills reveal calc-alkaline affinities and marked subduction-fluid signatures. Their calculated mantle potential temperature (1404 °C) is significantly lower than that expected for plume-derived melts (1570 °C), which is consistent with melting in a subduction-modified mantle wedge, supporting a continental rear-arc basin setting. The ~845–832 Ma mafic–ultramafic sills exhibit symmetrical geochemical zoning and two-stage emplacement, recording sustained magma recharge in the rear-arc basin. Furthermore, the ~830 Ma Fanjingshan granite is identified as a crust-derived, syn-collisional S-type granite. Synthesizing these findings, we demonstrate that the sedimentary and magmatic records collectively point to plate margin setting. A four-stage tectonic model is suggested: (1) pre-870 Ma passive margin without significant magmatic activity; (2) 870–835 Ma continental arc development at an active continental margin; (3) 835–820 Ma Yangtze–Cathaysia collision; and (4) post-820 Ma post-orogenic rifting. This work provides a robust regional case study, demonstrating that integrating records of deep magmatic processes with coeval shifts in sedimentary provenance and basin architecture is essential to reconstruct the complete evolution of ancient orogens. Full article

(This article belongs to the Special Issue Tracing Precambrian Pathways: Neoproterozoic Rocks and Their Global Context)

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38 pages, 12189 KB

Open AccessArticle

Insights into Elemental Migration-Enrichment Patterns and Microbial Communities in Tea Rhizosphere Soils Under Contrasting Lithological Backgrounds

by Ruyan Li, He Chang, Ping Pan, Lili Zhao, Yinxian Song, Yunhua Hou, Haowei Bian, Jiayi Gan, Shuai Li, Jibang Chen, Mengli Xie, Kun Long, Wei Zhang and Weikang Yang

Minerals 2026, 16(3), 333; https://doi.org/10.3390/min16030333 - 21 Mar 2026

Viewed by 658

Abstract

Elemental migration and enrichment are important processes influencing tea plant growth and the assembly of rhizosphere bacterial communities within the rock–soil–plant continuum. This study explores how soil parent materials (granite, quartz schist, and sericite schist) are potentially associated with these processes and their [...] Read more.

Elemental migration and enrichment are important processes influencing tea plant growth and the assembly of rhizosphere bacterial communities within the rock–soil–plant continuum. This study explores how soil parent materials (granite, quartz schist, and sericite schist) are potentially associated with these processes and their observed associations with the elemental composition of tea leaves. Exploratory statistical analyses revealed distinct, lithology-specific biogeochemical patterns that serve as a foundation for hypothesis generation. In granite soils, chlorite correlated with the mobility of Cr, Pb, Cu, Ni, Mg, and Na, coinciding with shifts in the relative abundances of Verrucomicrobia, Armatimonadetes, and Chloroflexi. In quartz schist, kaolinite exhibited notable correlations with the dynamics of Pb, Cr, Ni, Zn, and As, which were statistically linked to Planctomycetes, Proteobacteria, and Acidobacteria. Complex mineral–microbe interactions were observed in sericite schist soils, where clay minerals (e.g., chlorite, illite) were closely associated with the migration of multiple elements (Pb, K, Ca, Cd, As, Al, Fe, Zn), paralleling structural variations in communities of Actinobacteria, Planctomycetes, Chloroflexi, and Proteobacteria. Potassium (K), calcium (Ca), and manganese (Mn) showed bioaccumulation tendencies in tea leaves across all lithologies, with an enrichment capacity order of Ca > K > Mn > Mg > Na > Al. Exploratory Classification and Regression Tree (CART) analysis suggested that the migration of K, Ca, Cu, Zn, and Hg corresponded most closely with their soil concentrations. Manganese (Mn) exhibited a mineral-associated trend, with kaolinite content as a potential correlate, while cadmium (Cd) migration was statistically linked to the relative abundance of Armatimonadetes. These findings highlight potential candidate relationships between mineralogy, microbes, and elemental mobility rather than confirming causal mechanisms, emphasizing the need for further validation in larger or experimental datasets. Full article

(This article belongs to the Section Environmental Mineralogy and Biogeochemistry)

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26 pages, 10681 KB

Open AccessArticle

Metallogeny of Low-K Tholeiitic Magmas in Volcanic Arcs: Inferences from Petrology, Geochemistry and Micromineralogy of the Modern Mutnovsky Volcano Lavas (Kamchatka, Russia)

by Nadezhda Potapova, Pavel Kepezhinskas and Nikolai Berdnikov

Minerals 2026, 16(3), 332; https://doi.org/10.3390/min16030332 - 21 Mar 2026

Viewed by 713

Abstract

Metallogeny of low-K tholeiitic magmas in volcanic arcs is poorly documented and understood. The Mutnovsky volcano in Kamchatka erupted low-K tholeiitic basalt, basaltic andesite, andesite and dacite formed through partial melting of a depleted mantle wedge beneath the active front of the Kamchatka [...] Read more.

Metallogeny of low-K tholeiitic magmas in volcanic arcs is poorly documented and understood. The Mutnovsky volcano in Kamchatka erupted low-K tholeiitic basalt, basaltic andesite, andesite and dacite formed through partial melting of a depleted mantle wedge beneath the active front of the Kamchatka arc, followed by fractional crystallization in subarc magmatic conduits. Mineral microinclusions in Mutnovsky lavas are dominated by Cu-Ag chlorides and sulfides (±cerussite, baryte, cassiterite and Sb oxide), which show, along with the bulk rock Ag, Sn and Sb concentrations, a general increase during magmatic differentiation. Mutnovsky rocks are characterized by higher cumulative proportions of Cu-Ag sulfides and chlorides in comparison with the neighboring rear-arc Gorely and Bakening volcanoes, emphasizing the importance of S- and Cl-bearing fluids for their metallogenic evolution. Microinclusions in Mutnovsky tholeiites display certain similarities with ore mineral associations from epithermal and porphyry deposits in Kamchatka. Together with the enrichment of Mutnovsky lavas in Ag, Cu and Sb in reference to the bulk continental crust, this indicates a potential link between low-K tholeiitic magmas and Cu-Ag (±Sb, Sn) mineralization in volcanic arcs. Full article

(This article belongs to the Section Mineral Deposits)

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26 pages, 5110 KB

Open AccessArticle

Toward Robust Mineral Prospectivity Mapping: A Transformer-Based Global–Local Fusion Framework with Application to the Xiadian Gold Deposit

by Xiaoming Huang, Pancheng Wang and Qiliang Liu

Minerals 2026, 16(3), 331; https://doi.org/10.3390/min16030331 - 20 Mar 2026

Viewed by 534

Abstract

As mineral exploration increasingly targets deeper and more geologically complex terrains, the need for reliable predictive models becomes critical to mitigating exploration risk and improving cost efficiency. Correspondingly, the effectiveness of deep mineral exploration strategies depends substantially on the effectiveness and precision of [...] Read more.

As mineral exploration increasingly targets deeper and more geologically complex terrains, the need for reliable predictive models becomes critical to mitigating exploration risk and improving cost efficiency. Correspondingly, the effectiveness of deep mineral exploration strategies depends substantially on the effectiveness and precision of three-dimensional mineral prospectivity mapping (3D MPM) models. However, the inherent spatial non-stationarity—where ore grade variability changes across geological domains—and the strongly skewed distribution of high-grade samples present a dual challenge. Conventional methods, which primarily rely on mean-based regression, often struggle to adequately address this dual challenge, limiting their predictive performance in complex geological settings. To address these issues, this paper proposes a pinball-loss-guided, global–local fusion Transformer model within a unified framework for 3D MPM. It leverages a multi-head self-attention mechanism with global–local fusion to capture long-range dependencies and global geological contexts, while incorporating local feature extraction modules to adaptively model spatially varying mineralization controls, jointly optimized through a pinball loss function to address mineralization distribution skewness. The proposed framework was first rigorously evaluated using the Xiadian gold deposit as a case study. Bootstrap analysis of the ablation experiments confirmed its predictive performance in terms of quantile-specific accuracy and prediction interval (PI) calibration. Ten rounds of random data splits provided further confirmation of the model’s stability. Subsequently, the validated model was applied to prospectivity mapping in unexplored regions, leading to the delineation of several high-potential exploration targets. Finally, comparative analyses with state-of-the-art machine learning methods were conducted, which further validated the competitive fitting capability of the proposed framework. Full article

(This article belongs to the Special Issue 3D Mineral Prospectivity Modeling Applied to Mineral Deposits)

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20 pages, 5714 KB

Open AccessArticle

GeoCLA: An Integrated CNN-BiLSTM-Attention Framework for Geochemical Anomaly Detection in the Hatu Region, Xinjiang

by Yuheng Zhou, Yongzhi Wang, Shibo Wen, Yan Ning, Shaohui Wang, Guangpeng Zhang and Jingjing Wen

Minerals 2026, 16(3), 330; https://doi.org/10.3390/min16030330 - 20 Mar 2026

Cited by 1 | Viewed by 516

Abstract

Geochemical anomaly detection is a critical stage in mineral exploration, playing a key role in predicting potential mineral targets. Traditional methodologies often struggle to integrate the spatial structure of geochemical data with underlying geological constraints effectively. To address this limitation, we propose GeoCLA, [...] Read more.

Geochemical anomaly detection is a critical stage in mineral exploration, playing a key role in predicting potential mineral targets. Traditional methodologies often struggle to integrate the spatial structure of geochemical data with underlying geological constraints effectively. To address this limitation, we propose GeoCLA, a geochemical anomaly detection framework that integrates Convolutional Neural Networks (CNNs), Bidirectional Long Short-Term Memory (BiLSTM) networks, and an Attention Mechanism (AM). This integrated spatial-attention architecture captures complex correlations among multiple features to improve anomaly identification. The method constructs spatial sequential samples from geochemical data. The CNNs extract local spatial patterns, the BiLSTM models sequential dependencies, and the AM enhances the representation of critical features. Anomaly scores are computed using the reconstruction error between the model output and the original data. In addition, a fault-distance weighting factor is incorporated to build a comprehensive anomaly evaluation index. The proposed model was applied to the Hatu gold district in Xinjiang, China. Both visual analysis and quantitative evaluation demonstrate effectiveness, achieving a ROC-AUC of 0.86 and a mineral occurrence coverage rate of 97% within moderate-to-high anomaly prospective areas, significantly outperforming baseline methods. Full article

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

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31 pages, 4961 KB

Open AccessReview

Progress in the Modification and Utilization of Coal Gangue

by Xingyu Lu, Lijuan Wang, Yuhan Tang, Yi Zhou, Guocheng Lv and Libing Liao

Minerals 2026, 16(3), 329; https://doi.org/10.3390/min16030329 - 20 Mar 2026

Cited by 3 | Viewed by 1954

Abstract

Coal gangue, the primary solid by-product of coal mining, presents severe environmental challenges due to massive accumulation. At the same time, it represents potential as a secondary resource if properly utilized. This review systematically summarizes the mineralogical characteristics, modification strategies, and utilization pathways [...] Read more.

Coal gangue, the primary solid by-product of coal mining, presents severe environmental challenges due to massive accumulation. At the same time, it represents potential as a secondary resource if properly utilized. This review systematically summarizes the mineralogical characteristics, modification strategies, and utilization pathways of coal gangue. Current treatment methods, including thermal, chemical, and microbial activation, are discussed, highlighting their respective efficiencies, economic feasibility, and environmental impacts. Furthermore, this review emphasizes the transition of coal gangue from low-value disposal to high-value utilization. Representative applications are summarized, including its use as a precursor for advanced construction materials, as a functional material for environmental remediation, and as a feedstock for energy recovery. Finally, the major technological challenges and research gaps are identified. Future development should focus on intelligent sorting technologies, low-carbon activation processes, and synergistic multi-waste integration. These directions are expected to promote the transformation of coal gangue from an environmental liability into a valuable resource for the circular economy. Full article

(This article belongs to the Special Issue Clay Minerals for Environmental Remediation and Sustainable Energy)

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22 pages, 2795 KB

Open AccessArticle

Industrial Mineral-Based Ca-Rich Fly Ash Cement Mortars: 24-Month Durability Under Marine Exposure

by Nikolaos Chousidis

Minerals 2026, 16(3), 328; https://doi.org/10.3390/min16030328 - 20 Mar 2026

Cited by 1 | Viewed by 517

Abstract

This study investigates the long-term durability performance of Portland cement mortars incorporating 5% and 10% Ca-rich fly ash under 24 months of natural marine atmospheric exposure. An integrated experimental methodology was applied, combining gravimetric steel mass loss, half-cell potential monitoring (SCE), water-soluble chloride [...] Read more.

This study investigates the long-term durability performance of Portland cement mortars incorporating 5% and 10% Ca-rich fly ash under 24 months of natural marine atmospheric exposure. An integrated experimental methodology was applied, combining gravimetric steel mass loss, half-cell potential monitoring (SCE), water-soluble chloride determination at reinforcement depth, carbonation depth evaluation interpreted through the diffusion-based square-root model (x = k√t), and pore structure characterization by MIP and SEM. After 24 months, cumulative steel mass loss decreased by 26.6% (FA5) and 33.6% (FA10) relative to the reference mortar. The water-soluble chloride concentration at reinforcement depth was reduced from 976 mg/L in CM-REF to 875 mg/L (−10.2%) and 805 mg/L (−17.5%) in CM-FA5 and CM-FA10, respectively. Carbonation depth after 24 months decreased from 5.97 mm in the reference mortar to 4.56 mm (−23.6%) and 2.48 mm (−58.5%) for FA5 and FA10, confirming a transport-controlled mitigation of carbonation progression. Within the investigated replacement range, moderate Ca-rich fly ash incorporation produces measurable reductions in chloride availability, carbonation rate, and cumulative corrosion damage under realistic coastal exposure conditions, demonstrating that limited clinker substitution can yield substantial long-term durability benefits. These findings demonstrate that Ca-rich fly ash incorporation (5%–10%) effectively enhances resistance to chloride ingress, carbonation progression, and reinforcement corrosion under natural marine exposure, supporting its use as a performance-oriented strategy for durable, low-clinker mortar design in coastal infrastructure. Full article

(This article belongs to the Section Clays and Engineered Mineral Materials)

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Graphical abstract

1 pages, 125 KB

Open AccessCorrection

Correction: Jiang et al. Surface Charge and Size Evolution of Silica–Iron Colloidal Particles in Simulated Late-Archaean Seawater. Minerals 2025, 15, 1123

by Weiming Jiang, Xiao Wu, Hongmei Yang, Juan Fu, Qirui Zeng, Sizhe Li, Ruiyao Luo, Yiping Yang, Xiaoju Lin and Jianxi Zhu

Minerals 2026, 16(3), 327; https://doi.org/10.3390/min16030327 - 20 Mar 2026

Viewed by 309

Abstract

In the published publication [...] Full article

20 pages, 8759 KB

Open AccessArticle

Sedimentology and Geochemistry of the Permian Longtan Formation Transitional Shale, Sichuan Basin, Southwest China

by Yu Ji, Yuqiang Jiang, Zhanlei Wang, Ruiqi Gao and Jian Qian

Minerals 2026, 16(3), 326; https://doi.org/10.3390/min16030326 - 19 Mar 2026

Viewed by 591

Abstract

The transitional shale of the Upper Permian Longtan Formation in the Sichuan Basin is characterized by high organic matter abundance, wide distribution, and significant resource potential. This study systematically analyzes the sedimentary environment and geochemical characteristics of the Longtan Formation, clarifying the evolutionary [...] Read more.

The transitional shale of the Upper Permian Longtan Formation in the Sichuan Basin is characterized by high organic matter abundance, wide distribution, and significant resource potential. This study systematically analyzes the sedimentary environment and geochemical characteristics of the Longtan Formation, clarifying the evolutionary patterns of its sedimentary environment, detrital influx, paleoclimate, paleosalinity, and paleoredox conditions. The results indicate that the Longtan Formation can be divided into five Members. The Long 1 to Long 4 Members were predominantly deposited in littoral-marsh facies, whereas the Long 5 Member represents tidal flat–lagoon facies. Geochemical analyses indicate that the Long 4 Member exhibits the highest TOC content (3.37%–11.50%, avg. 6.39%), characterized by black shale interbedded with thin coal seams and pyrite bands. This interval corresponds to relatively low detrital input (Zr: 103–1124 ppm, avg. 697 ppm; Ti: 2589–3909 ppm, avg. 3408 ppm), a warm and humid paleoclimate (CIA: 88.4–96.8, avg. 93.6; Sr/Cu: 1.6–6.8, avg. 3.5), moderately elevated paleosalinity (Sr/Ba: 0.36–2.46, avg. 1.59), and oxic to intermittently reducing water conditions (U/Th: 0.21–0.68, avg. 0.37), making it the main interval for organic matter enrichment. From the Long 1 to Long 5 Members, the depositional environment evolved with progressively shallower water, decreasing terrigenous input, and increasingly oxic conditions. These changes, combined with high productivity and intermittently reducing conditions, collectively governed the accumulation and preservation of organic matter across the formation. Full article

(This article belongs to the Special Issue Diagenesis of Reservoir Sandstones: A Comparison Between Reservoirs and Non-Reservoirs)

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37 pages, 10819 KB

Open AccessArticle

Synergistic Diagenetic Evolution in Tight Sandstone-Shale Assemblage Within Lacustrine-Delta System: A Case Study in the Members 7-8 of the Yanchang Formation, Western Zhidan Area, Ordos Basin, China

by Zunqing Ma, Hongliang Wang, Fen Liang, Hanyun Ge, Zhengqin Ye and Hailong Yang

Minerals 2026, 16(3), 325; https://doi.org/10.3390/min16030325 - 19 Mar 2026

Viewed by 559

Abstract

Synergistic diagenetic evolution of sandstones and shales significantly impacts the quality of associated tight oil and shale oil reservoirs. Using integrated petrographic (thin sections, fluorescence thin sections, scanning electron microscopy with energy dispersive spectroscopy), mineralogical (X-ray diffraction), geochemical (stable carbon–oxygen isotopes, electron microprobe), [...] Read more.

Synergistic diagenetic evolution of sandstones and shales significantly impacts the quality of associated tight oil and shale oil reservoirs. Using integrated petrographic (thin sections, fluorescence thin sections, scanning electron microscopy with energy dispersive spectroscopy), mineralogical (X-ray diffraction), geochemical (stable carbon–oxygen isotopes, electron microprobe), organic petrologic, and petrophysical analyses, combined with basin burial and thermal history reconstruction, this study investigates the mechanisms and processes of synergistic diagenesis in the tight sandstone-shale assemblages of the 7th and 8th Members of the Yanchang Formation (Middle-Late Triassic) in the western Zhidan area, Ordos Basin, China. Controlled by basin evolution, the interbedded sandstones and shales, under shared burial-thermal conditions, exhibit strong synergy in four coupled processes: compaction, clay mineral evolution, shale fluid expulsion coupled with sandstone carbonate cementation, and shale hydrocarbon expulsion coupled with sandstone secondary porosity generation. This “fluid supply-response modification” relationship strongly influences diagenetic pathways and reservoir space evolution in sandstones, leading to variable reservoir quality among different sandstone-shale assemblages. Thicker-bedded sandstones interbedded with thinner-bedded shales represent potential targets for high-quality tight sandstone reservoirs. These findings provide a possible theoretical and methodological basis for identifying high-quality tight sandstone reservoirs in lacustrine-deltaic sandstone-shale assemblages. Full article

(This article belongs to the Section Mineral Exploration Methods and Applications)

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21 pages, 7513 KB

Open AccessArticle

The Geochronology and Geochemistry of Zircon and Apatite from the Shenshan Epimetamorphic Rocks in Ningdu, China: Implications for Ion-Adsorption-Type REE Metallogenesis

by Shuilong Wang, Huihu Fan, Luping Zeng, Dehai Wu, Wei Wan and Junpeng Wang

Minerals 2026, 16(3), 324; https://doi.org/10.3390/min16030324 - 19 Mar 2026

Viewed by 674

Abstract

In recent decades, ion-adsorption-type rare earth element (iREE) deposits have been widely documented in the weathering crusts of granitic and volcanic rocks and their geological characteristics and genetic mechanisms extensively studied. Ion-adsorption-type REE mineralization was documented for the first time in the weathered [...] Read more.

In recent decades, ion-adsorption-type rare earth element (iREE) deposits have been widely documented in the weathering crusts of granitic and volcanic rocks and their geological characteristics and genetic mechanisms extensively studied. Ion-adsorption-type REE mineralization was documented for the first time in the weathered crust overlying the epimetamorphic rocks in Ningdu County, China. In contrast to well-documented granite-derived weathering profiles, investigations of epimetamorphic rocks as protoliths for such REE deposits remain limited, particularly regarding the mineralogy of REE-bearing phases and the geochronology and geochemistry of their parent rocks. To address this gap, the present study combines comprehensive petrographic and mineralogical analyses of REE-mineralized Shenshan Formation phyllites with the U–Pb dating of zircon and apatite and trace element geochemical investigations. U–Pb zircon and apatite geochronology yields a protolith age of ca. 785 Ma for Shenshan Formation metamorphic rocks, consistent with mid-Neoproterozoic magmatism. REE-bearing minerals in the Shenshan Formation phyllites comprise allanite-(Ce), apatite, cerianite-(Ce), monazite-(Ce), rhabdophane-(La), rutile, Y-bearing thorianite and xenotime-(Y). Among these, apatite is the most abundant and likely the principal source of ionic REEs in the deposit. Ti-in-zircon thermometry indicates crystallization temperatures of 641–749 °C (mean ~704 °C), reflecting a prolonged magmatic–hydrothermal evolution. This extended history chiefly controlled the differentiation and redistribution of rare earth elements (REEs), thus governing their availability for subsequent supergene enrichment. Zircon-based oxygen fugacity (fO₂) estimates a range from −31.4 to −9.9 (mean −17.9), consistent with reduced magmatic conditions. Trace element correlation diagrams for zircon and apatite indicate that the intrusion underwent an extensive fractional crystallization of accessory phases (zircon, monazite, apatite, titanite, rutile) and plagioclase. The distribution patterns of trace elements further suggest that the Shenshan Formation protolith formed in a continental margin arc or arc-related orogenic belt setting, with geochemical signatures characteristic of an S-type granite. The Shenshan Formation phyllites in southern Jiangxi exhibit high REE abundances and host a labile assemblage of weatherable REE-bearing minerals, providing an optimal material framework for ion-adsorption-type REE deposits and indicating substantial mineralization potential. Full article

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

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20 pages, 3542 KB

Open AccessArticle

Geochemical Characteristics and Gas-Bearing Properties of Shale Gas in the Chang 7 Member of the Yanchang Formation, Ordos Basin

by Jin Han, Gaorun Zhong, Hengli Wang, Bangsheng Zhao, Yanjun Wu and Bingkun Meng

Minerals 2026, 16(3), 323; https://doi.org/10.3390/min16030323 - 19 Mar 2026

Viewed by 477

Abstract

Research on shale reservoir characteristics and the controlling factors of gas content is critical for predicting shale gas “sweet spots”. Based on integrated geochemical, mineralogical, and petrophysical analyses, this study investigates the mineral composition of shale and the influencing factors of gas content [...] Read more.

Research on shale reservoir characteristics and the controlling factors of gas content is critical for predicting shale gas “sweet spots”. Based on integrated geochemical, mineralogical, and petrophysical analyses, this study investigates the mineral composition of shale and the influencing factors of gas content in the Chang 7 Member of the Ordos Basin. The results show that (1) the shale clasts are mainly composed of quartz and feldspar, with the quartz contents in the range of 10.6%–29.7%, the feldspar contents in the range of 5.2%–38.2%, and the clay mineral contents in the range of 25.0%–70.5%. (2) The shale pore types include intergranular pores, granular dissolved pores and organic matter pores. The shale pores are mainly mesoporous and the pore sizes are mainly 6–9 nm with an average of 7.2 nm, accounting for 50% of the total pores population. (3) The shale kerogen maceral assemblage is composed primarily of the sapropel group, accounting for 77.2%–94.9% of the total macerals; vitrinite reflectance ranges from 0.80% to 1.13%, with a mean value of 0.83%. (4) The gas content of shale reservoirs is mainly controlled by temperature, pressure, total organic carbon (TOC) content, vitrinite reflectance, and reservoir physical properties. Among them, medium-to-large pores, TOC content, and pressure are the main controlling factors of shale gas content. The clay mineral content, vitrinite reflectance, and gas content constitute secondary controlling factors. Full article

(This article belongs to the Topic Reservoir Genesis and Quality Evolution in Hydrocarbon Systems)

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17 pages, 6338 KB

Open AccessArticle

Microwave-Assisted Composite Alkali Activation of Low-Calcium Fly Ash: Preparation and Analysis

by Zeyu Tang, Hongyue Yin, Xin Lv, Jingjie Jiang, Yu Gao, Yue Gao, Minmin Liu, Jianying Deng and Chul B. Park

Minerals 2026, 16(3), 322; https://doi.org/10.3390/min16030322 - 19 Mar 2026

Viewed by 761

Abstract

To promote the high-value utilization of fly ash (FA) and address the prolonged setting time and limited strength associated with conventional single-alkali activation, this study proposes a synergistic dual-alkali activation strategy using Ca(OH)₂ and Na₂SiO₃ in combination with microwave-assisted [...] Read more.

To promote the high-value utilization of fly ash (FA) and address the prolonged setting time and limited strength associated with conventional single-alkali activation, this study proposes a synergistic dual-alkali activation strategy using Ca(OH)₂ and Na₂SiO₃ in combination with microwave-assisted curing for low-calcium fly ash. Samples containing varying amounts of Ca(OH)₂ were systematically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), compressive strength testing, and pore structure analysis. The results show that Ca(OH)₂ facilitates the formation of calcium aluminosilicate hydrate (C-A-S-H) gel, while Na₂SiO₃ sustains the alkaline environment and enhances the dissolution of SiO₂ and Al₂O₃ from FA. The dual-alkali synergistic system, when coupled with microwave treatment, markedly refines the pore structure, increases the degree of polymerization, and improves compressive strength from 0.5 MPa to 1.7 MPa with increasing Ca(OH)₂ content. In addition, the prepared fly ash-based geopolymer (FABG) demonstrates pronounced pH-buffering capacity in acidic environments and exhibits antibacterial activity, primarily attributable to its sustained release of alkalinity. This work highlights that integrating dual-alkali activation with microwave curing can simultaneously enhance microstructural development, chemical stability, and functional performance in low-calcium FA systems, thereby offering a viable route for the development of sustainable and multifunctional green building materials derived from industrial solid waste. Full article

(This article belongs to the Special Issue Recycling of Industrial Waste for the Development of Sustainable Materials)

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26 pages, 6365 KB

Open AccessArticle

Geochemical Behaviors and Constraints on REE Enrichment in Weathered Crust of Shallow Metamorphic Rocks: Insights from the Getengzui Ion-Adsorption REE Deposit, South China

by Huihu Fan, Zhenya Chen, Luping Zeng, Dehai Wu, Fuyong Qi, Zhenghui Chen, Tao Wang, Wei Wan and Shuilong Wang

Minerals 2026, 16(3), 321; https://doi.org/10.3390/min16030321 - 19 Mar 2026

Viewed by 649

Abstract

Ion-adsorption rare earth element (REE) deposits represent strategic critical resources in China, which were traditionally considered to be predominantly hosted in granite weathering crusts. However, the recent discovery of new deposit types within the weathering crusts of shallow metamorphic rocks in South China [...] Read more.

Ion-adsorption rare earth element (REE) deposits represent strategic critical resources in China, which were traditionally considered to be predominantly hosted in granite weathering crusts. However, the recent discovery of new deposit types within the weathering crusts of shallow metamorphic rocks in South China has opened up novel exploration frontiers, while research on their metallogenic mechanisms remains insufficient. To elucidate the REE enrichment mechanisms in shallow metamorphic rock weathering crusts, this study focuses on the Getengzui ion-adsorption REE deposit in southern Jiangxi Province. Twenty-four samples were collected from the weathering crust profiles of the Qingbaikouan Shenshan and Kuli Formations. Multiple analytical approaches were employed, including major and trace element analysis, Chemical Index of Alteration (CIA), Base Leaching Index (BA), and quantitative evaluation of element mass transfer coefficients (τ). Trace element spider diagrams, REE distribution patterns, and A-CN-K diagram analysis were also utilized. The results reveal that the weathering crusts have progressed to the middle–late stage of chemical weathering. The average CIA value is 83 for the middle-upper part of the completely weathered horizon in the Kuli Formation. In contrast, for the completely weathered horizon in the Shenshan Formation, the value is 86. Intense chemical weathering has resulted in the near-complete decomposition of primary silicate minerals and extensive leaching of base cations. This progress has created an acidic pore water environment, which is critical for REE mobilization. REEs exhibit characteristics of in situ secondary enrichment, with significant enrichment of ΣREE in the middle-upper part of the completely weathered horizon. The peak τ(ΣREE) values reach 0.78 and 2.43 for the Kuli and Shenshan Formations, respectively. Apatite dissolution is identified as the primary source of REE ions. Differences exist in the geochemical mobility sequences of elements between the two formations. REE enrichment is controlled by multi-stage geochemical barriers, including an oxidation barrier and a clay adsorption barrier. The oxidation barrier preferentially fixes Ce⁴⁺, whereas the clay adsorption barrier serves as the dominant mechanism for large-scale REE enrichment. Parent rock lithology is the primary factor governing the efficiency, scale, and fractionation characteristics of REE enrichment. The Kuli Formation is favorable for forming the thick, large-scale orebodies enriched in light rare earth elements (LREEs). In the contrast, the Shenshan Formation tends to host higher-grade orebodies, characterized by a relatively balanced ratio of LREEs and heavy rare earth elements (HREEs). This study clarifies the main controlling factors for ion-adsorption REE mineralization in two shallow metamorphic rocks. It thereby provides a theoretical basis for future exploration. This framework is applicable to analogous REE resources within shallow metamorphic rock distributions across South China and nationwide. Full article

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

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26 pages, 4465 KB

Open AccessArticle

K and Mg in Soil Clay Reservoirs: Responses in Soil Solution Composition and Implications for Natural Fertility in Acidic Environments

by Sara Alcalde-Aparicio, Eduardo Alonso-Herrero and Manuel Vidal-Bardán

Minerals 2026, 16(3), 320; https://doi.org/10.3390/min16030320 - 19 Mar 2026

Cited by 1 | Viewed by 1111

Abstract

Soils play a fundamental role in plant nutrition as primary sources of potassium (K) and magnesium (Mg), whose availability depends on soil properties and environmental conditions. The composition of major cations in the soil solution is governed by interacting factors, including soil texture, [...] Read more.

Soils play a fundamental role in plant nutrition as primary sources of potassium (K) and magnesium (Mg), whose availability depends on soil properties and environmental conditions. The composition of major cations in the soil solution is governed by interacting factors, including soil texture, acidity, mineralogical composition, and seasonal variability during the growing cycle. This study examines the availability, mobility, and seasonal dynamics of K and Mg in the soil solution of seven naturally managed soils across four distinct periods of a complete growing season beginning in spring. An integrated field and laboratory approach was applied to assess the influence of clay mineralogy on K and Mg behavior and overall soil fertility. Seasonal soil samples were analyzed for mineral composition, total elemental chemistry, exchangeable cation pools, and soil solution chemistry. Total elemental concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS), and clay mineral assemblages were identified by X-ray diffraction (XRD), focusing on 2:1 clay minerals, mixed-layer phases, and hydroxy-interlayered minerals (HIMs). The soils were dominated by 2:1 and mixed-layer assemblages, including illite/smectite (Ill/Sm), mica/illite–vermiculite (M/Vm), and chlorite/smectite (Chl/Sm), as well as transitional HIMs such as hydroxy-interlayered smectite (HIS) and hydroxy-interlayered vermiculite (HIV). Exchangeable Mg (0.28–1.30 cmolc kg⁻¹) and K (0.12–0.97 cmolc kg⁻¹) occurred in relatively high amounts, with maximum base saturation values of 13.14% (Mg) and 4.55% (K). Soil solution concentrations ranged from 1.60 to 3.00 ppm for K⁺ and 0.90–1.70 ppm for Mg²⁺, indicating substantial mobility and enrichment from the solid phase. These findings demonstrate that 2:1 clay minerals and mixed-layer phases act as key reservoirs regulating K and Mg exchangeability and release under natural acidic conditions, thereby sustaining soil fertility and nutrient availability for plant uptake. Full article

(This article belongs to the Section Clays and Engineered Mineral Materials)

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21 pages, 2366 KB

Open AccessArticle

Molecular Modeling of Arsenic Species Adsorption on Clay Minerals and in the Presence of Organic Matter

by Sudip Sengupta, Kallol Bhattacharyya, Jajati Mandal and Asoke Prasun Chattopadhyay

Minerals 2026, 16(3), 319; https://doi.org/10.3390/min16030319 - 18 Mar 2026

Viewed by 1103

Abstract

Arsenic (As) contamination of soils is a critical environmental and geochemical concern, with its mobility and bioavailability largely controlled by molecular-scale interactions with soil minerals. This study investigates the adsorption behavior of arsenate [As(V)] and arsenious acid [As(III)] on major clay minerals to [...] Read more.

Arsenic (As) contamination of soils is a critical environmental and geochemical concern, with its mobility and bioavailability largely controlled by molecular-scale interactions with soil minerals. This study investigates the adsorption behavior of arsenate [As(V)] and arsenious acid [As(III)] on major clay minerals to elucidate fundamental controls on As retention in soil and sediment systems. Molecular modeling approaches were employed to investigate these interactions. Density functional theory (DFT) calculations were performed on cluster models of illite, chlorite, montmorillonite, and kaolinite to evaluate adsorption configurations and binding energies of arsenate and arsenious acid. In addition, semiempirical (PM6) and classical force-field (UFF) methods were used to examine the influence of vermicompost-derived organic matter on arsenate-mineral interactions. Multiple adsorption configurations, including atop atom, bridge, three-fold filled, and three-fold hollow sites, were evaluated, and binding energies were calculated with correction for basis set superposition error. The results indicate that three-fold hollow sites are the most favorable, with As(V) binding energies of 60–65 kcal mol⁻¹ on illite, chlorite, and montmorillonite, reaching 75 kcal mol⁻¹ on kaolinite at a surface distance of 2.7 Å. In contrast, As(III) shows weaker and energetically flatter adsorption, with binding energies of 28–54 kcal mol⁻¹ and larger equilibrium distances of 3.2–4.0 Å. Modeling of vermicompost addition suggests a substantial reduction in arsenate binding on most clay minerals, except illite, indicating competitive or disruptive interactions at mineral surfaces. These findings provide quantitative, atomistic insight into mineral- and amendment-specific controls on As stabilization and mobility in soil and sediment systems. Full article

(This article belongs to the Special Issue Geochemistry and Mineralogy of Soil and Sediment)

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29 pages, 29190 KB

Open AccessArticle

Metallogenic Prediction for Copper–Nickel Sulfide Deposits in the Eastern and Central Tianshan Based on Multi-Modal Feature Fusion

by Haonan Wang, Bimin Zhang, Miao Xie, Yue Sun, Wei Ye, Chunfang Dong, Zimu Yang and Xueqiu Wang

Minerals 2026, 16(3), 318; https://doi.org/10.3390/min16030318 - 18 Mar 2026

Viewed by 578

Abstract

The deep integration of machine learning technology with geological prospecting has brought to the forefront a key challenge: how to construct geological-mineralization models by fusing multi-source data, select model features with guidance from metallogenic factors, build multi-source metallogenic prediction models with geological constraints, [...] Read more.

The deep integration of machine learning technology with geological prospecting has brought to the forefront a key challenge: how to construct geological-mineralization models by fusing multi-source data, select model features with guidance from metallogenic factors, build multi-source metallogenic prediction models with geological constraints, and ultimately achieve a thorough integration of domain knowledge and machine intelligence. The Eastern-Central Tianshan region is one of China’s most important copper–nickel mineral resource bases, predominantly hosting magmatic copper–nickel sulfide deposits with significant resource potential. In this context, this paper proposes a metallogenic prediction model based on multi-modal feature fusion technology. The model employs a Residual Neural Network (ResNet) incorporating a Squeeze-and-Excitation (SE) attention mechanism and a Multi-Layer Perceptron (MLP) to extract features from different modalities. It integrates multi-source data, including geochemical information, geological metallogenic factors, and aeromagnetic data. A cross-modal feature interaction module, constructed using attention weighting and a gating mechanism, enables deep fusion of the features. After training, the model achieved a prediction accuracy of 97% on the test set. Compared to a unimodal model constructed using Random Forest, the confidence and discriminative capability of the training results were significantly enhanced, validating the effectiveness of multi-modal feature fusion. Applying the trained model to the study area, a total of 11 prospective metallogenic zones were delineated. These include 4 zones in the peripheries of known deposits and 7 zones in previously unexplored (blank) areas. Notably, some known mineral occurrences fall within the predicted blank-area targets, validating the feasibility and significant value of multi-modal feature fusion in mineral prediction. This work provides a novel methodology for the subsequent integrated processing of multi-source data. Full article

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

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18 pages, 1871 KB

Open AccessReview

Platinum Group Element Mineralization in Mongolia: Geological Setting, Occurrences, and Exploration Potential

by Jaroslav Dostal, Ochir Gerel and Turbold Sukhbaatar

Minerals 2026, 16(3), 317; https://doi.org/10.3390/min16030317 - 18 Mar 2026

Viewed by 838

Abstract

Platinum group elements (PGE) are six rare highly siderophile metals which have similar chemical characteristics and occur together in mineral deposits: platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir) and osmium (Os). In nature, they tend to exist in a metallic [...] Read more.

Platinum group elements (PGE) are six rare highly siderophile metals which have similar chemical characteristics and occur together in mineral deposits: platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir) and osmium (Os). In nature, they tend to exist in a metallic state or bond with sulfur and arsenic and occur as trace accessory minerals predominantly in mafic and ultramafic rocks. High industrial demand together with their scarcity in crustal rocks has been reflected in their inclusion in 2025 US Government’s List of Critical Minerals, European Union’s List of Critical Raw Materials and Mongolian List of 11 Critical Minerals. Although Mongolia is not currently a producer, it hosts four types of potentially economic PGE deposits: (1) Podiform chromitites associated with ophiolites; (2) Ni-Cu-PGE sulfide mineralization of rift-related mafic–ultramafic intrusions; (3) Alaskan–Uralian type arc related zoned mafic–ultramafic intrusions; and (4) Placers. Particularly promising are Permian Ni-Cu-PGE sulfide bearing mafic–ultramafic intrusions of the Khangai large igneous province which bear resemblance to mineralized Permian intrusions in Russia (e.g., Norilsk-Talnakh) and N.W. China (e.g., Kalatongke; Tarim basin). In addition, sub-economic ophiolite-hosted PGE mineralization can be extracted as a by-product during chromite mining. There is also the potential for PGE recovery as a by-product in existing gold placer operations in areas hosting ophiolitic massifs and Alaskan–Uralian type intrusions. Mongolia is a promising frontier for PGE exploration and mining. Full article

(This article belongs to the Special Issue Critical Metal Minerals, 2nd Edition)

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15 pages, 4289 KB

Open AccessArticle

Multi-Scale Process Mineralogy of Cd and Ag in a Pb-Zn Ore: Implications for Recovery Optimization

by Xiaoliang Zhang, Yong Cheng, Yang Liu, Huiqi Li, Chuanxiong Cai, Yiming Wen, Jun Ma, Saihua Xu, Xiangdong Niu, Yongfeng Lu, Lijuan Zuo, Juqiong Deng, Qi Nie, Guoxin Shan and Jiajun Tang

Minerals 2026, 16(3), 316; https://doi.org/10.3390/min16030316 - 18 Mar 2026

Viewed by 510

Abstract

Efficient recovery of critical metals from complex polymetallic ores relies on clarifying their mineralogical occurrence. A Cd-Ag-rich Pb-Zn ore from southwestern China was investigated via a multi-scale process mineralogy approach integrating reflected-light microscopy, TIMA and LA-ICP-MS. Systematic analysis was conducted on ore texture, [...] Read more.

Efficient recovery of critical metals from complex polymetallic ores relies on clarifying their mineralogical occurrence. A Cd-Ag-rich Pb-Zn ore from southwestern China was investigated via a multi-scale process mineralogy approach integrating reflected-light microscopy, TIMA and LA-ICP-MS. Systematic analysis was conducted on ore texture, mineral liberation characteristics, and the occurrence and distribution of Ag and Cd. The ore is a medium–low grade Pb-Zn deposit (Pb 0.81%, Zn 4.33%) with economically recoverable associated Cd (0.066%) and Ag (5.04 ppm), dominated by sphalerite (7.74%), galena (1.39%), pyrite (3.92%), quartz (47.80%) and calcite (18.66%). TIMA analysis revealed poor liberation of sphalerite and galena, with fully liberated particles accounting for <30%. LA-ICP-MS results showed that Cd is highly enriched in sphalerite (average 5982 ppm, 98%) mainly in isomorphous form, while Ag is dispersed in pyrite (average 178 ppm, 56%), galena (average 227 ppm, 25%) and sphalerite (average 31 ppm, 19%), also primarily as isomorphs; partial Cd in pyrite occurs as micro-inclusions. The multi-scale mineralogical data provide a scientific basis for resource utilization, indicating the necessity of fine grinding and differentiated recovery strategies: “zinc depression followed by lead flotation” for Pb-Zn recovery, the establishment of a comprehensive Ag recovery system with Pb-Zn-Fe as carriers for Ag recovery, and “Zn-carried Cd” flotation for Cd recovery. This study verifies the effectiveness of combined TIMA and LA-ICP-MS in elucidating critical metal occurrence, and provides a mineralogy-based process design for the sustainable processing of such complex ores. Full article

(This article belongs to the Section Mineral Processing and Extractive Metallurgy)

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11 pages, 6346 KB

Open AccessArticle

The Anisotropic Permeability Insights of Nano-Scale Pore Networks Evolution in the Overmature Shales

by Yanshuai Tang, Tianguo Tang, Xiaohang Bao, Xiujiang Fan and Lei Zhou

Minerals 2026, 16(3), 315; https://doi.org/10.3390/min16030315 - 17 Mar 2026

Viewed by 398

Abstract

Permeability is affected by nanopores and pore structure, and anisotropic permeability is the result of shale lamination, orientation, and stratification of minerals. To understand the reasons for permeability anisotropy, the pore networks of over-mature shale has been studied. The mineral compositions, petrophysical properties, [...] Read more.

Permeability is affected by nanopores and pore structure, and anisotropic permeability is the result of shale lamination, orientation, and stratification of minerals. To understand the reasons for permeability anisotropy, the pore networks of over-mature shale has been studied. The mineral compositions, petrophysical properties, and pore structures of the Lower Cambrian Niutitang Formation shales were analyzed using subcritical gas adsorption, field-emission scanning electron microscopic, and X-ray micro-computed tomographic methods. Quartz, clay minerals, and carbonate are the dominant minerals in the shales. The bedding-parallel and bedding-perpendicular permeabilities are 1.25–46.21 × 10⁻² and 1.38–6.62 × 10⁻² mD, respectively. The anisotropy of permeability, which is the ratio between the bedding-parallel and bedding-perpendicular permeability, is 0.21–26.87. The micropore and Barrett–Joyner–Halenda pore volumes are 0.54–3.62 and 0.05–0.69 mL/100 g, respectively. The bedding-parallel permeability is correlated positively with the micropore and Barrett–Joyner–Halenda pore volumes. Thin-section observations indicate the shales exhibit a bedding-parallel alignment of phyllosilicate minerals and planar deformation bands. The scanning electron microscopy shows deformation of the lamination and parallel alignment of the clay minerals due to compaction or differential compaction over coarser-grained quartz grains. The scanning electron microscopy images and subcritical gas adsorption data indicate that the pore fracture system is parallel to bedding and formed after diagenesis. Furthermore, X-ray micro-computed tomographic analysis shows that the micro-fractures are also preferentially oriented, parallel to bedding. Full article

(This article belongs to the Topic Reservoir Characteristics and Evolution Mechanisms of the Shale, 2nd Edition)

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25 pages, 5627 KB

Open AccessArticle

Performance of Electro-Geochemical Survey in Locating Hidden Lead–Zinc–Antimony Deposits: A Case Study of the Bancai Mining Area in Hechi, Guangxi

by Hong Zhao, Meilan Wen, Wen Gao, Panfeng Liu, Yuxiong Jiang, Xiaohan Zhang, Jiajia Ma, Guangkun Luo and Xuanheng Ren

Minerals 2026, 16(3), 314; https://doi.org/10.3390/min16030314 - 17 Mar 2026

Viewed by 443

Abstract

The demand for lead–zinc–antimony ore resources in China has increased steadily, while shallow deposits are approaching depletion, leading to intensified exploration for deep, concealed orebodies. Electro-geochemical surveys, as a penetrative geochemical exploration technique, are particularly effective in areas with thick overburden. In this [...] Read more.

The demand for lead–zinc–antimony ore resources in China has increased steadily, while shallow deposits are approaching depletion, leading to intensified exploration for deep, concealed orebodies. Electro-geochemical surveys, as a penetrative geochemical exploration technique, are particularly effective in areas with thick overburden. In this study, the Bancai area in Hechi, Guangxi, was selected to evaluate the applicability of this method for concealed mineral exploration. Feasibility testing was conducted along the A4 profile over an engineering-controlled orebody. Distinct electro-geochemical anomalies were identified directly above the known orebody, showing strong spatial correspondence and favorable ore-indicating characteristics, confirming the effectiveness of the method in the study area. Based on the deposit’s geological characteristics, prospecting indicators were established by integrating geological features, electro-geochemical responses, and wall-rock alteration. A geological electro-geochemical prospecting model was constructed for the Bancai mining area and applied for deep exploration of the Bancai B block. By analyzing the spatial distribution of electro-geochemical anomalies and integrating geological conditions, mineralization potential, and related factors, three prospective target areas were delineated to provide guidance for subsequent explorations. Among these targets, Target Area III exhibits favorable structural conditions, well-developed calcite veins, and pronounced superposition of multi-element geochemical anomalies, indicating considerable potential for further mineral exploration. Full article

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

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20 pages, 4485 KB

Open AccessArticle

Geochronology, Genesis and Redox Condition of the Lisong Granites in the Guposhan Region, Nanling Range: Constraints from Zircon U-Pb Dating, Whole-Rock Geochemistry, and Apatite Geochemistry

by Weijian Zhou, Mengqing Tang, Wenjing She, Yongxin Zhou, Liu Yang, Gaofeng Du, Na Liu, Jinyu Zhang and Jingya Cao

Minerals 2026, 16(3), 313; https://doi.org/10.3390/min16030313 - 17 Mar 2026

Viewed by 526

Abstract

The Guposhan ore field, located in the Nanling metallogenic belt, is well known for large-scale Sn-W mineralization genetically linked to the Late Jurassic Guposhan pluton. The Lisong pluton, a product of regional magmatism, occurs in the central part of the Guposhan ore field. [...] Read more.

The Guposhan ore field, located in the Nanling metallogenic belt, is well known for large-scale Sn-W mineralization genetically linked to the Late Jurassic Guposhan pluton. The Lisong pluton, a product of regional magmatism, occurs in the central part of the Guposhan ore field. However, the critical factors responsible for the absence of intensive Sn polymetallic mineralization in the Lisong pluton remain poorly understood. Our geochronological results show that the coarse-grained hornblende-bearing and hornblende-free biotite monzogranites of the Lisong pluton were emplaced at 162.9 ± 1.5 Ma and 162.2 ± 2.3 Ma, respectively, which are contemporaneous with the Guposhan pluton. Geochemically, these intrusions are characterized by high SiO₂, Al₂O₃, and total alkalis (K₂O + Na₂O), high Ga/Al ratios (3.09–3.69), and peraluminous compositions (A/CNK = 1.15–1.23), consistent with high K calc-alkaline A-type granites. Similar to the adjacent Guposhan pluton, the Lisong granites yield variable _εHf(t) values from −3.0 to 5.7, apatite ⁸⁷Sr/⁸⁶Sr ratios of 0.69747–0.71190, and old two-stage Hf model ages (T_DM2) of 0.85–1.40 Ga. These features suggest that the Lisong and Guposhan granites may share a common magma source involving mixing of crustal and mantle-derived melts. Apatite grains from the Lisong granites display negative Eu anomalies (δEu = 0.03–0.22) and near-normal to positive Ce anomalies (δCe = 0.99–1.07), which we interpret to reflect plagioclase fractional crystallization and reduced melt conditions, respectively. Bulk rock geochemistry and multi-element systematics of the Lisong granites indicate that they represent early-stage magmatic products. Their relatively low differentiation signatures were unfavorable for Sn enrichment and mineralization in the melt, which likely explains the lack of intensive Sn polymetallic mineralization in the Lisong pluton. Full article

(This article belongs to the Special Issue The Application of Accessory Mineral Geochemistry in Ore Deposit Studies)

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Open AccessArticle

Geological Characteristics and Genesis of the Greisen-Hosted Nb-Ta Mineralization in the Qidashan Iron Deposit, Liaoning Province, China, and Its Implications

by Yang Xiao, Rongzhen Gao, Qing Sun, Jianfei Fu, Yuzeng Yao, Sanshi Jia and Jiale Chen

Minerals 2026, 16(3), 312; https://doi.org/10.3390/min16030312 - 16 Mar 2026

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Abstract

The newly identified greisen-hosted Nb-Ta mineralization in the Qidashan iron deposit, Liaoning Province, China, offers a unique opportunity to explore how hydrothermal processes contribute to the enrichment of critical metals. In this study, an integrated analytical approach of petrographic observation and scanning electron [...] Read more.

The newly identified greisen-hosted Nb-Ta mineralization in the Qidashan iron deposit, Liaoning Province, China, offers a unique opportunity to explore how hydrothermal processes contribute to the enrichment of critical metals. In this study, an integrated analytical approach of petrographic observation and scanning electron microscopy–energy-dispersive spectrometer (SEM-EDS), electron probe microanalyzer (EPMA), and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) U-Pb dating of columbite-group minerals (CGMs) were employed to systematically decipher the paragenetic sequence, micro-structure, elemental composition and mineralization age of CGMs, aiming at the genesis of greisen-hosted Nb-Ta mineralization. The mineralization is characterized by the abundant occurrence of CGMs. Three generations of CGMs and two mineralization stages are distinguished: stage I contains CGM Is and CGM IIs, with Nb₂O₅ ranging from 25.7 to 69.56 wt.% and Ta₂O₅ from 5.8 to 52.5 wt.%; stage II contains CGM IIIs, with Nb₂O₅ between 59.5 and 71.5 wt.% and Ta₂O₅ between 3.5 and 16.2 wt.%. CGM Is consist of euhedral, homogeneous crystals of more than 100 μm, exhibit low Ta/(Nb + Ta) ratios (0.05–0.06) and high Mn/(Fe + Mn) ratios (0.19–0.26), and belong to columbite-Fe. CGM IIs generally overgrow on CGM Is with hydrothermal overprinting textures, and show significant compositional gaps compared to CGM Is, exhibiting higher Ta/(Nb + Ta) ratios (0.13–0.55) and restricted Mn/(Fe + Mn) ratios (0.15–0.18), with some belonging to columbite-Fe and others to tantalite-Fe, which reveals a transition from magma to “hydrosilicate fluid”. CGM IIIs are mainly anhedral and homogeneous, with a grain size of less than 50 μm. However, some CGM IIIs overgrow on CGM IIs and/or CGM Is with patchy textures indicative of subsequent hydrothermal overprinting of hydrosilicate fluid, forming a coarse-grain size over 100 μm. CGM IIIs are characterized by lower Ta/(Nb + Ta) ratios (0.03–0.14) and variable Mn/(Fe + Mn) ratios (0.08–0.26), and they belong to columbite-Fe. LA-ICP-MS U-Pb dating yields weighted mean ²⁰⁶Pb/²³⁸U ages of 2646 ± 15 Ma for stage I and 2500 ± 28 Ma for stage II, indicating two-stage Nb-Ta mineralization. The early mineralization may correlate with the partial melting of volcanic–sedimentary rocks due to the geothermal anomalies associated with ~2.7 Ga submarine volcanism, and the late mineralization formed by the magmatic hydrothermal activities related to emplacement of the Qidashan granite in 2.5 Ga. We therefore propose that the two-stage greisen-hosted Nb-Ta mineralization probably widely occurred in these sedimentary–metamorphic iron deposits in the Anshan–Benxi area and even in the northern edge of the North China Craton, and it may provide new insights for evaluating the Nb-Ta resource potential in similar Algoma-type iron deposits globally. 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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25 pages, 2146 KB

Open AccessEditor’s ChoiceArticle

Machine Learning-Based Predictive Modelling of Key Operating Parameters in an Industrial-Scale Wet Vertical Stirred Media Mill

by Okay Altun, Aydın Kaya, Ali Seydi Keçeli, Ece Uzun, Meltem Güler and Nurettin Alper Toprak

Minerals 2026, 16(3), 311; https://doi.org/10.3390/min16030311 - 16 Mar 2026

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Abstract

To the authors’ knowledge, this is the first industrial machine learning (ML) study focused on wet vertical stirred media milling. The study develops and validates machine learning (ML) models to predict the key operating parameters, namely mill discharge product size, mill feed slurry [...] Read more.

To the authors’ knowledge, this is the first industrial machine learning (ML) study focused on wet vertical stirred media milling. The study develops and validates machine learning (ML) models to predict the key operating parameters, namely mill discharge product size, mill feed slurry flow rate, mill power draw, and the specific energy consumption of an industrial wet vertical stirred media mill operating at a copper plant. A physics-guided workflow was adapted, combining relief coefficient-based variable screening with fundamental stirred milling principles to define 20 different structured model input scenarios. In the scope, six regression approaches, linear regression (LR), fine tree regression (FTR), support vector regression (SVR), random forest regression (RFR), artificial neural network regression (ANN), and Gaussian process regression (GPR), were trained and validated using plant sensor data and evaluated using R² and RMSE. Overall performance was reasonable, with GPR providing the highest predictive accuracy, followed by RFR/ANN, while LR, SVR, and FTR performed lower. The potential benefit of feed size was also assessed conceptually through an upper-bound sensitivity analysis, representing a best-case scenario where an online feed size measurement would be available. Because the feed size descriptor (F₈₀) was not independently measured but derived from an energy–size relationship, the associated accuracy gains are reported as theoretical upper-bound indications rather than independent predictive capability. Overall, the findings support ML-based decision support in stirred milling operations and motivate future work using independently measured feed size (or reliable proxy sensing). Full article

(This article belongs to the Collection Advances in Comminution: From Crushing to Grinding Optimization)

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16 pages, 3615 KB

Open AccessArticle

Mineralogical and Geochemical Characteristics of Biotite in Granite from the Guanfang Tungsten Deposit, Bozhushan, Southeastern Yunnan, and Their Implications for Petrogenesis and Mineralization

by Dai Zhang, Liurunxuan Chen, Xianchao Chen, Xuelong Liu, Jiehu Zhou, Bode Lu, Ruohan Zuo and Shitao Zhang

Minerals 2026, 16(3), 310; https://doi.org/10.3390/min16030310 - 16 Mar 2026

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Abstract

The Guanfang tungsten deposit in the Bozhushan ore district, southeastern Yunnan, is genetically linked to Late Yanshanian granitic intrusions. To elucidate the petrogenesis and mineralization potential of the causative granite, this study presents a detailed mineral chemical analysis of biotite from the Guanfang [...] Read more.

The Guanfang tungsten deposit in the Bozhushan ore district, southeastern Yunnan, is genetically linked to Late Yanshanian granitic intrusions. To elucidate the petrogenesis and mineralization potential of the causative granite, this study presents a detailed mineral chemical analysis of biotite from the Guanfang pluton using electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The biotite crystals exhibit relatively high euhedrality, show no obvious alteration features, and are chemically characterized by reduced Na and Ca contents. These features, along with petrographic observations, confirm its origin as primary magmatic biotite. Crystallization conditions, calculated from biotite chemistry, indicate temperatures of 700–720 °C and pressures of 1.22–1.73 kbar, corresponding to a mesozonal emplacement depth of 4.6–6.5 km. Oxygen fugacity estimates, plotting near the Ni-NiO buffer, reveal an oxidized magmatic environment. Geochemical discrimination diagrams suggest the Guanfang granite exhibits transitional features between S-type and I-type affinities and is classified as a syn-melting (high-temperature) type. The biotite contains relatively low F (0.71–0.97 wt%), but elevated Cl (0.13–0.20 wt%) and Sn (43–56 µg/g) contents. This specific geochemical signature—combined with the medium- to high-temperature crystallization setting—is highly favorable for W-Sn mineralization. Furthermore, the high-Ti, syn-melting character of the granite implies additional potential for Cu-Pb-Zn-Au-Ag polymetallic mineralization. This study employs biotite chemistry to assess the petrogenesis and metallogenic potential of the Guanfang granite. The subsequent discovery of industrial ore bodies corresponding to some of the elements identified as having metallogenic potential confirms the feasibility of this approach. Accordingly, this method provides a new tool for future exploration in the Bozhushan district. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: "Critical and Strategic Minerals", 2nd Edition)

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Minerals, Volume 16, Issue 3 (March 2026) – 114 articles

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