Minerals

15 pages, 1589 KiB

Open AccessArticle

Optimising Nature-Based Treatment Systems for Management of Mine Water

by Catherine J. Gandy, Beate Christgen and Adam P. Jarvis

Minerals 2025, 15(7), 765; https://doi.org/10.3390/min15070765 - 21 Jul 2025

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Deployment of nature-based systems for mine water treatment is constrained by system size, and the evidence suggests decreasing hydraulic conductivity (K_sat) of organic substrates over time compromises performance. In lab-scale continuous-flow reactors, we investigated (1) the geochemical and hydraulic performance [...] Read more.

Deployment of nature-based systems for mine water treatment is constrained by system size, and the evidence suggests decreasing hydraulic conductivity (K_sat) of organic substrates over time compromises performance. In lab-scale continuous-flow reactors, we investigated (1) the geochemical and hydraulic performance of organic substrates used in nature-based systems for metals removal (via bacterial sulfate reduction) from mine water, and then (2) the potential to operate systems modestly contaminated with Zn (0.5 mg/L) at reduced hydraulic residence times (HRTs). Bioreactors containing limestone, straw, and wood chips, with and without compost and/or sewage sludge all achieved 88%–90% Zn removal, but those without compost/sludge had higher K_sat (929–1546 m/d). Using a high K_sat substrate, decreasing the HRT from 15 to 9 h had no impact on Zn removal (92.5% to 97.5%). Although the sulfate reduction rate decreased at a shorter HRT, microbial analysis showed high relative abundance (2%–7%) of sulfate reducing bacteria, and geochemical modelling pointed to ZnS(s) precipitation as the main attenuation mechanism (mean ZnS saturation index = 3.91–4.23). High permeability organic substrate treatment systems operated at a short HRT may offer potential for wider deployment of such systems, but pilot-scale testing under ambient environmental conditions is advisable. Full article

(This article belongs to the Special Issue Characterization and Management of Mine Waters)

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22 pages, 5215 KiB

Open AccessArticle

Analysis and Modeling of Elastic and Electrical Response Characteristics of Tight Sandstone in the Kuqa Foreland Basin of the Tarim Basin

by Juanli Cui, Kui Xiang, Xiaolong Tong, Yanling Shi, Zuzhi Hu and Liangjun Yan

Minerals 2025, 15(7), 764; https://doi.org/10.3390/min15070764 - 21 Jul 2025

Viewed by 227

Abstract

This study addresses the limitations of conventional evaluation methods caused by low porosity, strong heterogeneity, and complex pore structures in tight sandstone reservoirs. Through integrated rock physics experiments and multi-physical field modeling, the research systematically investigates the coupled response mechanisms between electrical and [...] Read more.

This study addresses the limitations of conventional evaluation methods caused by low porosity, strong heterogeneity, and complex pore structures in tight sandstone reservoirs. Through integrated rock physics experiments and multi-physical field modeling, the research systematically investigates the coupled response mechanisms between electrical and elastic parameters. The experimental approach includes pore structure characterization, quantitative mineral composition analysis, resistivity and polarizability measurements under various saturation conditions, P- and S-wave velocity testing, and scanning electron microscopy (SEM) imaging. The key findings show that increasing porosity leads to significant reductions in resistivity and elastic wave velocities, while also increasing surface conductivity. Specifically, clay minerals enhance surface conductivity through interfacial polarization effects and decrease rock stiffness, which exacerbates wave velocity attenuation. Furthermore, resistivity exhibits a nonlinear negative correlation with water saturation, with sharp increases at low saturation levels due to the disruption of conductive pathways. By integrating the Modified Generalized Effective Medium Theory of Induced Polarization (MGEMTIP) and Kuster–Toksöz models, this study establishes quantitative relationships between porosity, saturation, and electrical/elastic parameters, and constructs cross-plot templates that correlate elastic wave velocities with resistivity and surface conductivity. These analyses reveal that high-porosity, high-saturation zones are characterized by lower resistivity and wave velocities, coupled with significantly higher surface conductivity. The proposed methodology significantly improves the accuracy of reservoir evaluation and enhances fluid identification capabilities, providing a solid theoretical foundation for the efficient exploration and development of tight sandstone reservoirs. Full article

(This article belongs to the Special Issue Electromagnetic Inversion for Deep Ore Explorations)

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12 pages, 4221 KiB

Open AccessArticle

The Effects of Amino Acids on the Polymorphs and Magnesium Content of Calcium–Magnesium Carbonate Minerals

by Chonghong Zhang, Yuyang Jiang and Shuhao Qian

Minerals 2025, 15(7), 763; https://doi.org/10.3390/min15070763 - 21 Jul 2025

Viewed by 287

Abstract

Calcium–magnesium (Ca–Mg) carbonates are among the most widely distributed carbonates in the Earth’s surface environment, and their formation mechanisms are of great significance for revealing geological environmental changes and carbon sequestration processes. In this study, the gas diffusion method was employed with L-glutamic [...] Read more.

Calcium–magnesium (Ca–Mg) carbonates are among the most widely distributed carbonates in the Earth’s surface environment, and their formation mechanisms are of great significance for revealing geological environmental changes and carbon sequestration processes. In this study, the gas diffusion method was employed with L-glutamic acid, L-glycine, and L-lysine as nucleation templates for carbonate minerals to systematically investigate their regulatory effects on the mineralization of Ca–Mg carbonates. The results demonstrated that L-glycine, with the shortest length, was more conducive to forming aragonite, whereas acidic L-glutamic acid, which contains more carboxyl groups, was more beneficial for the structural stability of aragonite. The morphology of the Ca-Mg carbonate minerals became more diverse and promoted the formation of spherical and massive mineral aggregates under the action of amino acids. Moreover, the amino acids significantly increased the MgCO₃ content in Mg calcite (L-glutamic acid: 10.86% > L-glycine: 7.91% > L-lysine: 6.63%). The acidic L-glutamic acid likely promotes the dehydration and incorporation of Mg²⁺ into the Mg calcite lattice through the preferential adsorption of Mg²⁺ via its side-chain carboxyl groups. This study shows how amino acid functional groups influence Ca–Mg carbonate mineralization and provides insights into biogenic Mg-rich mineral origins and advanced mineral material synthesis. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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10 pages, 404 KiB

Open AccessArticle

Flotation Separation of Chalcopyrite and Molybdenite by Eco-Friendly Microorganism Depressant Bacillus tropicus

by Guanghua Ai, Guosheng Xiao and Bo Feng

Minerals 2025, 15(7), 762; https://doi.org/10.3390/min15070762 - 21 Jul 2025

Viewed by 316

Abstract

In this study, Bacillus tropicus (BT), a non-toxic and eco-friendly microorganism, was employed to substitute traditional inorganic depressants in the flotation separation of copper-molybdenum sulfides. Single mineral flotation tests were performed to examine BT’s impact on the flotation behavior of molybdenite and chalcopyrite. [...] Read more.

In this study, Bacillus tropicus (BT), a non-toxic and eco-friendly microorganism, was employed to substitute traditional inorganic depressants in the flotation separation of copper-molybdenum sulfides. Single mineral flotation tests were performed to examine BT’s impact on the flotation behavior of molybdenite and chalcopyrite. The results indicated that excessive BT inhibited the flotation of both minerals, reducing their recoveries below 40%. At a BT dosage of 2.5 kg/t and pH 9.0, chalcopyrite recovery was 74.10%, while molybdenite recovery was 20.47%, achieving an effective separation of the two minerals. BT’s adsorption mechanism on molybdenite and chalcopyrite was analyzed through contact angle tests, thermogravimetric analysis, and Fourier transform infrared spectroscopy. These analyses revealed that increased BT absorption on molybdenite enhanced its surface hydrophilicity. This research offers a novel perspective on utilizing microorganisms as efficient flotation reagents. Full article

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

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23 pages, 30355 KiB

Open AccessArticle

Controls on Stylolite Formation in the Upper Cretaceous Kometan Formation, Zagros Foreland Basin, Iraqi Kurdistan

by Hussein S. Hussein, Ondřej Bábek, Howri Mansurbeg, Juan Diego Martín-Martín and Enrique Gomez-Rivas

Minerals 2025, 15(7), 761; https://doi.org/10.3390/min15070761 - 20 Jul 2025

Viewed by 995

Abstract

Stylolites are ubiquitous diagenetic products in carbonate rocks. They play a significant role in enhancing or reducing fluid flow in subsurface reservoirs. This study unravels the relationship between stylolite networks, carbonate microfacies, and the elemental geochemistry of Upper Cretaceous limestones of the Kometan [...] Read more.

Stylolites are ubiquitous diagenetic products in carbonate rocks. They play a significant role in enhancing or reducing fluid flow in subsurface reservoirs. This study unravels the relationship between stylolite networks, carbonate microfacies, and the elemental geochemistry of Upper Cretaceous limestones of the Kometan Formation (shallow to moderately deep marine) in Northern Iraq. Stylolites exhibit diverse morphologies across mud- and grain-supported limestone facies. Statistical analyses of stylolite spacing, wavelength, amplitude, and their intersections and connectivity indicate that grain size, sorting, and mineral composition are key parameters that determine the geometrical properties of the stylolites and stylolite networks. Stylolites typically exhibit weak connectivity and considerable vertical spacing when hosted in packstone facies with moderate grain sorting. Conversely, mud-supported limestones, marked by poor sorting and high textural heterogeneity, host well-developed stylolite networks characterized by high amplitude and frequent intersections, indicating significant dissolution and deformation processes. Stylolites in mud-supported facies are closely spaced and present heightened amplitudes and intensified junctions, with suture and sharp-peak type. This study unveils that stylolites can potentially enhance porosity in the studied formation. Full article

(This article belongs to the Special Issue Stylolites: Development, Properties, Inversion and Scaling)

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20 pages, 16432 KiB

Open AccessArticle

Application of Clustering Methods in Multivariate Data-Based Prospecting Prediction

by Xiaopeng Chang, Minghua Zhang, Liang Chen, Sheng Zhang, Wei Ren and Xiang Zhang

Minerals 2025, 15(7), 760; https://doi.org/10.3390/min15070760 - 20 Jul 2025

Viewed by 275

Abstract

Mining and analyzing information from multiple sources—such as geophysics and geochemistry—is a key aspect of big data-driven mineral prediction. Clustering, which groups large datasets based on distance metrics, is an essential method in multidimensional data analysis. The Two-Step Clustering (TSC) approach offers advantages [...] Read more.

Mining and analyzing information from multiple sources—such as geophysics and geochemistry—is a key aspect of big data-driven mineral prediction. Clustering, which groups large datasets based on distance metrics, is an essential method in multidimensional data analysis. The Two-Step Clustering (TSC) approach offers advantages by handling both categorical and continuous variables and automatically determining the optimal number of clusters. In this study, we applied the TSC method to mineral prediction in the northeastern margin of the Jiaolai Basin by: (i) converting residual gravity and magnetic anomalies into categorical variables using Ward clustering; and (ii) transforming 13 stream sediment elements into independent continuous variables through factor analysis. The results showed that clustering is sensitive to categorical variables and performs better with fewer categories. When variables share similar distribution characteristics, consistency between geophysical discretization and geochemical boundaries also influences clustering results. In this study, the (3 × 4) and (4 × 4) combinations yielded optimal clustering results. Cluster 3 was identified as a favorable zone for gold deposits due to its moderate gravity, low magnetism, and the enrichment in F1 (Ni–Cu–Zn), F2 (W–Mo–Bi), and F3 (As–Sb), indicating a multi-stage, shallow, hydrothermal mineralization process. This study demonstrates the effectiveness of combining Ward clustering for variable transformation with TSC for the integrated analysis of categorical and numerical data, confirming its value in multi-source data research and its potential for further application. Full article

(This article belongs to the Special Issue Application of Big Data Mining, Machine Learning and Artificial Intelligence in Geoscience, 2nd Edition)

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24 pages, 6323 KiB

Open AccessArticle

Study on Creep Characteristics of High-Volume Fly Ash-Cement Backfill Considering Initial Damage

by Shuokang Wang, Jingjing Yan, Zihui Dong, Hua Guo, Yuanzhong Yang and Naseer Muhammad Khan

Minerals 2025, 15(7), 759; https://doi.org/10.3390/min15070759 - 19 Jul 2025

Viewed by 374

Abstract

To reveal the long-term deformation behavior of high-volume fly ash-based backfill under continuous mining and backfilling, a fly ash–cement backfill material with 73.0% fly ash content was developed, and creep characteristic tests considering initial damage were conducted. The results demonstrate that: (1) A [...] Read more.

To reveal the long-term deformation behavior of high-volume fly ash-based backfill under continuous mining and backfilling, a fly ash–cement backfill material with 73.0% fly ash content was developed, and creep characteristic tests considering initial damage were conducted. The results demonstrate that: (1) A calculation method for the initial damage of backfill based on stress–strain hysteresis loop cycles is proposed, with cumulative characteristics of initial damage across mining phases analyzed; (2) Creep behaviors of backfill affected by initial damage are investigated, revealing the weakening effect of initial damage on long-term bearing capacity; (3) An enhanced, nonlinear plastic damage element is developed, enabling the construction of an HKBN constitutive model capable of characterizing the complete creep behavior of backfill materials. The research establishes a theoretical framework for engineering applications of backfill materials with early-age strength below 5 MPa, while significantly enhancing the utilization efficiency of coal-based solid wastes. Full article

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23 pages, 15718 KiB

Open AccessArticle

Trace and Rare-Earth-Element Chemistry of Quartz from the Tuztaşı Low-Sulfidation Epithermal Au-Ag Deposit, Western Türkiye: Implications for Gold Exploration from Quartz Mineral Chemistry

by Fatih Özbaş, Essaid Bilal and Ahmed Touil

Minerals 2025, 15(7), 758; https://doi.org/10.3390/min15070758 - 19 Jul 2025

Viewed by 579

Abstract

The Tuztaşı low-sulfidation epithermal Au–Ag deposit (Biga Peninsula, Türkiye) records a multi-stage hydrothermal history that can be interpreted through the trace and rare-earth-element (REE) chemistry of quartz. High-precision LA-ICP-MS analyses of five representative quartz samples (23 ablation spots; 10 analytically robust) reveal two [...] Read more.

The Tuztaşı low-sulfidation epithermal Au–Ag deposit (Biga Peninsula, Türkiye) records a multi-stage hydrothermal history that can be interpreted through the trace and rare-earth-element (REE) chemistry of quartz. High-precision LA-ICP-MS analyses of five representative quartz samples (23 ablation spots; 10 analytically robust) reveal two fluid stages. Early fluids were cold, dilute meteoric waters (δ¹⁸O₍H₂O₎ ≈ −6.8 to +0.7‰), whereas later fluids circulated deeper, interacted with felsic basement rocks, and evolved in composition. Mineralized quartz displays marked enrichment in As (raw mean = 2854 ± 6821 ppm; filtered mean = 70 ± 93 ppm; one spot 16,775 ppm), K (498 ± 179 ppm), and Sb (57.8 ± 113 ppm), coupled with low Ti/Al (<0.005) and elevated Ge/Si (0.14–0.65 µmol mol⁻¹). Chondrite-normalized REE patterns show pronounced but variable LREE enrichment ((La/Yb)_n ≤ 45.3; ΣLREE/ΣHREE up to 10.8) and strongly positive Eu anomalies (δEu ≤ 9.3) with slightly negative Ce anomalies (δCe ≈ 0.29); negligible Ce–Eu covariance (r² ≈ 0.05) indicates discrete redox pulses. These signatures indicate chemically evolved, reducing fluids conducive to Au–Ag deposition. By contrast, barren quartz is characterized by lower pathfinder-element contents, less fractionated REE profiles, higher Ti/Al, and weaker Eu anomalies. A composite exploration toolkit emerges: As > 700 ppm, As/Sb > 25, Ti/Al < 0.005, Ge/Si > 0.15 µmol mol⁻¹, and δEu ≫ 1 reliably identify ore-bearing zones when integrated with δ¹⁸O data and fluid-inclusion microthermometry from earlier studies on the same vein system. This study provides one of the first systematic applications of integrated trace-element and REE analysis of quartz to a Turkish low-sulfidation epithermal system, offering an applicable model for vectoring mineralization in analogous settings worldwide. Full article

(This article belongs to the Section Mineral Deposits)

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18 pages, 7598 KiB

Open AccessArticle

Recovery of Fine Rare Earth Minerals from Simulated Tin Tailings by Carrier Magnetic Separation: Selective Heterogeneous Agglomeration with Coarse Magnetite Particles

by Ilhwan Park, Topan Satria Gumilang, Rinaldi Yudha Pratama, Sanghee Jeon, Carlito Baltazar Tabelin, Theerayut Phengsaart, Muhammad Bilal, Youhei Kawamura and Mayumi Ito

Minerals 2025, 15(7), 757; https://doi.org/10.3390/min15070757 - 19 Jul 2025

Viewed by 415

Abstract

The demand for rare earth elements (REEs) is continuously increasing due to the important roles they play in low-carbon and green energy technologies. Unfortunately, the global REE reserves are limited and concentrated in only a few countries, so the reprocessing of alternative resources [...] Read more.

The demand for rare earth elements (REEs) is continuously increasing due to the important roles they play in low-carbon and green energy technologies. Unfortunately, the global REE reserves are limited and concentrated in only a few countries, so the reprocessing of alternative resources like tailings is of critical importance. This study investigated carrier magnetic separation using coarse magnetite particles as a carrier to recover finely ground monazite from tailings. The monazite and carrier surfaces were modified by sodium oleate (NaOL) to improve the hydrophobic interactions between them. The results of zeta potential and contact angle measurements implied the selective adsorption of NaOL onto the surfaces of the monazite and magnetite particles. Although their hydrophobicity increased, heterogenous agglomeration between them was not substantial. To improve heterogenous agglomeration, emulsified kerosene was utilized as a bridging liquid, resulting in more extensive attachment of fine monazite particles onto the surfaces of carrier particles and a dramatic improvement in monazite recovery by magnetic separation—from 0% (without carrier) to 70% (with carrier). A rougher–scavenger–cleaner carrier magnetic separation can produce REE concentrates with a total rare earth oxide (TREO) recovery of 80% and a grade of 9%, increased from 3.4%, which can be further increased to 23.2% after separating REEs and the carrier. 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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17 pages, 1652 KiB

Open AccessArticle

Evaluation of Binderless Briquettes as Potential Feed for the Electric Arc Furnaces at Barro Alto, Brazil

by Johnny Obakeng Mogalanyane, Natasia Naudé and Andrie Mariana Garbers-Craig

Minerals 2025, 15(7), 756; https://doi.org/10.3390/min15070756 - 19 Jul 2025

Viewed by 327

Abstract

Barro Alto processes nickel laterite ore using rotary kilns and six-in-line rectangular electric arc furnaces. This study evaluated the briquetting of ferronickel ore to reduce kiln fines, improve furnace charge permeability, and enhance process safety. Binderless briquettes were produced from screened ore at [...] Read more.

Barro Alto processes nickel laterite ore using rotary kilns and six-in-line rectangular electric arc furnaces. This study evaluated the briquetting of ferronickel ore to reduce kiln fines, improve furnace charge permeability, and enhance process safety. Binderless briquettes were produced from screened ore at two size fractions (−6.3 mm and −12.5 mm), with moisture contents of 16% and 24%, cured under closed and open conditions. The physical and metallurgical properties of the briquettes were assessed using ISO standard tests. The results confirmed successful agglomeration of the ore into binderless briquettes. Screening the run-of-mine (ROM) ore improved the feed quality, increasing the NiO grade from 2.0% to 2.2% in the −6.3 mm fraction. The briquettes from the −6.3 mm ore at 16% moisture exhibited the highest green strength (559 N). Higher moisture content reduced the briquette strength and increased both the reduction disintegration and decrepitation indices. The decrepitation index increased from 0.33% to 0.61% for the −6.3 mm briquettes when the moisture increased from 16% to 24%. The reduction levels were 33.4% and 39.2% for −6.3 mm and −12.5 mm briquettes with 16% moisture, respectively. This study concludes that optimal performance was achieved using −6.3 mm ore, 16% moisture, and open curing, thereby balancing reduction efficiency and mechanical stability. Full article

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

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23 pages, 8957 KiB

Open AccessArticle

Geometallurgical Cluster Creation in a Niobium Deposit Using Dual-Space Clustering and Hierarchical Indicator Kriging with Trends

by João Felipe C. L. Costa, Fernanda G. F. Niquini, Claudio L. Schneider, Rodrigo M. Alcântara, Luciano N. Capponi and Rafael S. Rodrigues

Minerals 2025, 15(7), 755; https://doi.org/10.3390/min15070755 - 19 Jul 2025

Viewed by 443

Abstract

Alkaline carbonatite complexes are formed by magmatic, hydrothermal, and weathering geological events, which modify the minerals present in the rocks, resulting in ores with varied metallurgical behavior. To better spatially distinguish ores with distinct plant responses, creating a 3D geometallurgical block model was [...] Read more.

Alkaline carbonatite complexes are formed by magmatic, hydrothermal, and weathering geological events, which modify the minerals present in the rocks, resulting in ores with varied metallurgical behavior. To better spatially distinguish ores with distinct plant responses, creating a 3D geometallurgical block model was necessary. To establish the clusters, four different algorithms were tested: K-Means, Hierarchical Agglomerative Clustering, dual-space clustering (DSC), and clustering by autocorrelation statistics. The chosen method was DSC, which can consider the multivariate and spatial aspects of data simultaneously. To better understand each cluster’s mineralogy, an XRD analysis was conducted, shedding light on why each cluster performs differently in the plant: cluster 0 contains high magnetite content, explaining its strong magnetic yield; cluster 3 has low pyrochlore, resulting in reduced flotation yield; cluster 2 shows high pyrochlore and low gangue minerals, leading to the best overall performance; cluster 1 contains significant quartz and monazite, indicating relevance for rare earth elements. A hierarchical indicator kriging workflow incorporating a stochastic partial differential equation (SPDE) trend model was applied to spatially map these domains. This improved the deposit’s circular geometry reproduction and better represented the lithological distribution. The elaborated model allowed the identification of four geometallurgical zones with distinct mineralogical profiles and processing behaviors, leading to a more robust model for operational decision-making. Full article

(This article belongs to the Special Issue Geostatistical Methods and Practices for Specific Ore Deposits)

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18 pages, 2330 KiB

Open AccessArticle

Adaptive Differential Evolution Algorithm for Induced Polarization Parameters in Frequency-Domain Controlled-Source Electromagnetic Data

by Lei Zhou, Tianjun Cheng, Min Yao, Jianzhong Cheng, Xingbing Xie, Yurong Mao and Liangjun Yan

Minerals 2025, 15(7), 754; https://doi.org/10.3390/min15070754 - 18 Jul 2025

Viewed by 279

Abstract

The frequency-domain controlled-source electromagnetic method (CSEM) has been widely used in fields such as oil and gas and mineral resource exploration. In areas with a significant IP response, the CSEM signals will be modified by the IP response of the subsurface. Accurately extracting [...] Read more.

The frequency-domain controlled-source electromagnetic method (CSEM) has been widely used in fields such as oil and gas and mineral resource exploration. In areas with a significant IP response, the CSEM signals will be modified by the IP response of the subsurface. Accurately extracting resistivity and polarization information from CSEM signals may significantly improve the exploration interpretations. In this study, we replaced real resistivity with the Cole–Cole complex resistivity model in a forward simulation of the CSEM to obtain electric field responses that included both induced polarization and electromagnetic effects. Based on this, we used the adaptive differential evolution algorithm to perform a 1-d inversion of these data to extract both the resistivity and IP parameters. Inversion of the electric field responses from representative three-layer geoelectric models, as well as from a more realistic seven-layer model, showed that the inversions were able to effectively recover resistivity and polarization information from the modeled responses, validating our methodology. The electric field response of the real geoelectric model, with 20% random noise added, was then used to simulate actual measured CSEM signals, as well as subjected to multiple inversion tests. The results of these tests continued to accurately reflect the resistivity and polarization information of the model, confirming the applicability and reliability of the algorithm. These results have significant implications for the processing and interpretation of CSEM data when induced polarization effects merit consideration and are expected to promote the use of the CSEM in more fields. Full article

(This article belongs to the Special Issue Electromagnetic Inversion for Deep Ore Explorations)

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21 pages, 2430 KiB

Open AccessArticle

Mechanisms and Genesis of Acidic Goaf Water in Abandoned Coal Mines: Insights from Mine Water–Surrounding Rock Interaction

by Zhanhui Wu, Xubo Gao, Chengcheng Li, Hucheng Huang, Xuefeng Bai, Lihong Zheng, Wanpeng Shi, Jiaxin Han, Ting Tan, Siyuan Chen, Siyuan Ma, Siyu Li, Mengyun Zhu and Jiale Li

Minerals 2025, 15(7), 753; https://doi.org/10.3390/min15070753 - 18 Jul 2025

Viewed by 274

Abstract

The formation of acidic goaf water in abandoned coal mines poses significant environmental threats, especially in karst regions where the risk of groundwater contamination is heightened. This study investigates the geochemical processes responsible for the generation of acidic water through batch and column [...] Read more.

The formation of acidic goaf water in abandoned coal mines poses significant environmental threats, especially in karst regions where the risk of groundwater contamination is heightened. This study investigates the geochemical processes responsible for the generation of acidic water through batch and column leaching experiments using coal mine surrounding rocks (CMSR) from Yangquan, China. The coal-bearing strata, primarily composed of sandstone, mudstone, shale, and limestone, contain high concentrations of pyrite (up to 12.26 wt%), which oxidizes to produce sulfuric acid, leading to a drastic reduction in pH (approximately 2.5) and the mobilization of toxic elements. The CMSR samples exhibit elevated levels of arsenic (11.0 mg/kg to 18.1 mg/kg), lead (69.5 mg/kg to 113.5 mg/kg), and cadmium (0.6 mg/kg to 2.6 mg/kg), all of which exceed natural crustal averages and present significant contamination risks. The fluorine content varies widely (106.1 mg/kg to 1885 mg/kg), with the highest concentrations found in sandstone. Sequential extraction analyses indicate that over 80% of fluorine is bound in residual phases, which limits its immediate release but poses long-term leaching hazards. The leaching experiments reveal a three-stage release mechanism: first, the initial oxidation of sulfides rapidly lowers the pH (to between 2.35 and 2.80), dissolving heavy metals and fluorides; second, slower weathering of aluminosilicates and adsorption by iron and aluminum hydroxides reduce the concentrations of dissolved elements; and third, concentrations stabilize as adsorption and slow silicate weathering regulate the long-term release of contaminants. The resulting acidic goaf water contains extremely high levels of metals (with aluminum at 191.4 mg/L and iron at 412.0 mg/L), which severely threaten groundwater, particularly in karst areas where rapid cross-layer contamination can occur. These findings provide crucial insights into the processes that drive the acidity of goaf water and the release of contaminants, which can aid in the development of effective mitigation strategies for abandoned mines. Targeted management is essential to safeguard water resources and ecological health in regions affected by mining activities. 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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34 pages, 3875 KiB

Open AccessArticle

Basis for a New Life Cycle Inventory for Metals from Mine Tailings Using a Conceptual Model Tool

by Katherine E. Raymond, Mike O’Kane, Mark Logsdon, Yamini Gopalapillai, Kelsey Hewitt, Johannes Drielsma and Drake Meili

Minerals 2025, 15(7), 752; https://doi.org/10.3390/min15070752 - 18 Jul 2025

Viewed by 302

Abstract

Life Cycle Impact Assessments (LCIAs) examine the environmental impacts of products using life cycle inventories (LCIs) of quantified inputs and outputs of a product through its life cycle. Currently, estimated impacts from mining are dominated by long-term metal release from tailings due to [...] Read more.

Life Cycle Impact Assessments (LCIAs) examine the environmental impacts of products using life cycle inventories (LCIs) of quantified inputs and outputs of a product through its life cycle. Currently, estimated impacts from mining are dominated by long-term metal release from tailings due to inaccurate assumptions regarding metal release and transport within and from mine materials. A conceptual model approach is proposed to support the development of a new database of LCI data, applying mechanistic processes required for the release and transport of metals through tailings and categorizing model inputs into ‘bins’. The binning approach argues for accuracy over precision, noting that precise metal release rates are likely impossible with the often-limited data available. Three case studies show the range of forecasted metal release rates, where even after decades of monitoring within the tailings and underlying aquifer, metal release rates span several orders of magnitude (<100 mg/L to >100,000 mg/L sulfate at the Faro Mine). The proposed tool may be useful for the development of a new database of LCI data, as well as to analyze mine’s regional considerations during designs for risk evaluation, management and control prior to development, when data is also scarce. Full article

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

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23 pages, 25056 KiB

Open AccessArticle

Mineral Chemistry and Whole-Rock Analysis of Magnesian and Ferroan Granitic Suites of Magal Gebreel, South Eastern Desert: Clues for Neoproterozoic Syn- and Post-Collisional Felsic Magmatism

by El Saeed R. Lasheen, Gehad M. Saleh, Amira El-Tohamy, Farrage M. Khaleal, Mabrouk Sami, Ioan V. Sanislav and Fathy Abdalla

Minerals 2025, 15(7), 751; https://doi.org/10.3390/min15070751 - 17 Jul 2025

Viewed by 459

Abstract

The article provides a comprehensive analysis of the Magal Gebreel granitic suites (MGGs) using petrological (fieldwork, petrography, mineral chemistry, and bulk rock analysis) aspects to infer their petrogenesis and emplacement setting. Our understanding of the development of the northern portion of the Arabian [...] Read more.

The article provides a comprehensive analysis of the Magal Gebreel granitic suites (MGGs) using petrological (fieldwork, petrography, mineral chemistry, and bulk rock analysis) aspects to infer their petrogenesis and emplacement setting. Our understanding of the development of the northern portion of the Arabian Nubian Shield is significantly improved by the Neoproterozoic granitic rocks of the seldom studied MGGs in Egypt’s south Eastern Desert. According to detailed field, mineralogical, and geochemical assessments, they comprise syn-collision (granodiorites) and post-collision (monzogranites, syenogranites, and alkali feldspar rocks). Granodiorite has strong positive Pb, notable negative P, Ti, and Nb anomalies, and is magnesian in composition. They have high content of LREEs (light rare-earth elements) compared to HREEs (heavy rare-earth elements) and clear elevation of LFSEs (low-field strength elements; K Rb, and Ba) compared to HFSEs (high-field strength elements; Zr and Nb), which are in accord with the contents of I-type granites from the Eastern Desert. In this context, the granodiorites are indicative of an early magmatic phase that probably resulted from the partial melting of high K-mafic sources in the subduction zone. Conversely, the post-collision rocks have low contents of Mg#, CaO, P₂O₅, MgO, Fe₂O₃, Sr, and Ti, and high SiO₂, Fe₂O₃/MgO, Nb, Ce, and Ga/Al, suggesting A-type features with ferroan affinity. Their P, Nb, Sr, Ba, and Ti negative anomalies are in accord with the findings for Eastern Desert granites of the A2-type. Furthermore, they exhibit a prominent negative anomaly in Eu and a small elevation of LREEs in relation to HREEs. The oxygen fugacity (fO₂) for the rocks under investigation can be calculated using the biotite chemistry. The narrow Fe/(Fe + Mg) ratio range (0.6–0.75) indicates that they crystallized under moderately oxidizing conditions between ~QFM +0.1 and QFM +1. The A-type rocks were formed by the partial melting of a tonalite source (underplating rocks) in a post-collisional environment during the late period of extension via slab delamination. The lithosphere became somewhat impregnated with particular elements as a result of the interaction between the deeper crust and the upwelling mantle. Full article

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

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20 pages, 1677 KiB

Open AccessEditor’s ChoiceReview

Froth Flotation of Lepidolite—A Review

by Xusheng Yang, Bo Feng and Longxia Jiang

Minerals 2025, 15(7), 750; https://doi.org/10.3390/min15070750 - 17 Jul 2025

Viewed by 356

Abstract

As one of the important lithium resource sources, lepidolite has become a new energy strategic resource research hot spot. The efficient flotation of lepidolite directly affects the recovery and economic value of lithium resources. This paper systematically reviews the flotation research progress of [...] Read more.

As one of the important lithium resource sources, lepidolite has become a new energy strategic resource research hot spot. The efficient flotation of lepidolite directly affects the recovery and economic value of lithium resources. This paper systematically reviews the flotation research progress of lepidolite, focusing on the influence of the type of capture agent and process parameters (pH, activator, and depressant) on flotation. In view of the separation problems caused by the similarity of the surface properties of lepidolite and its associated gangue minerals (albite, feldspar, and quartz), the strategies for regulating the crystal structure of the minerals and their surface properties are analyzed. In addition, the lepidolite flotation process and its challenges are summarized, including poor selectivity of chemicals, fine mineral embedded size, easy to form sludge, and insufficient environmental friendliness, etc. The future development direction of lepidolite flotation technology is also prospected, which provides theoretical support and reference for the efficient recovery of lepidolite. Full article

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

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22 pages, 4184 KiB

Open AccessArticle

Comparative Study of the Effect of Particle Size on Flotation Kinetics of Raw and Waste Coal

by Jovica Sokolović, Ivana Đolović, Dejan Tanikić, Zoran Štirbanović and Ivana Ilić

Minerals 2025, 15(7), 749; https://doi.org/10.3390/min15070749 - 17 Jul 2025

Viewed by 211

Abstract

This study examines the influence of particle size on the flotation kinetics parameters of both raw and waste fine coal originating from the anthracite mine “Vrška Čuka”, Serbia. Flotation kinetics modeling was performed using MATLAB for nonlinear regression analysis, based on coal flotation [...] Read more.

This study examines the influence of particle size on the flotation kinetics parameters of both raw and waste fine coal originating from the anthracite mine “Vrška Čuka”, Serbia. Flotation kinetics modeling was performed using MATLAB for nonlinear regression analysis, based on coal flotation test data. The correlation between total combustible recovery and flotation time was determined using the following models: Classical, Klimpel, Kelsall, Modified Kelsall, and Fully Mixed. The coefficients of determination range from 0.9724 (the Klimpel model) to 1 (the modified Kelsall model) for raw coal and from 0.8609 (the Klimpel model) to 0.9981 (the modified Kelsall model) for waste coal. Although both the Classical and Modified Kelsall models demonstrated a good correlation with the experimental data, the Modified Kelsall model provided a slightly better fit. The maximum values of the flotation rate constant (k) for both coals were obtained for the particle size-class (−0.1 + 0.053) mm for the Classical model and (−0.2 + 0.1) mm for the modified Kelsall model. The relation between flotation kinetics constant (k) and average particle size value (d_sr) was estimated for the Classical model and the modified Kelsall model. It was observed that the flotation kinetics constant (k) for coal particle size could be predicted satisfactorily. Full article

(This article belongs to the Special Issue Mineral Processing and Recycling Technologies for Sustainable Future)

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21 pages, 5158 KiB

Open AccessArticle

Genesis of the Erentaolegai Silver Deposit, Inner Mongolia, Northeast China: Evidence from Fluid Inclusion and H-O-S Isotopes

by Yushan Zuo, Xintong Dong, Zhengxi Gao, Liwen Wu, Zhao Liu, Jiaqi Xu, Shanming Zhang and Wentian Mi

Minerals 2025, 15(7), 748; https://doi.org/10.3390/min15070748 - 17 Jul 2025

Viewed by 392

Abstract

The Erentaolegai silver deposit is located within the Derbugan metallogenic belt in the eastern segment of the Central Asia–Mongolia giant orogenic belt. The ore bodies are primarily hosted in the volcanic rocks of the Middle Jurassic Tamulangou Formation of the Mesozoic. The mineralization [...] Read more.

The Erentaolegai silver deposit is located within the Derbugan metallogenic belt in the eastern segment of the Central Asia–Mongolia giant orogenic belt. The ore bodies are primarily hosted in the volcanic rocks of the Middle Jurassic Tamulangou Formation of the Mesozoic. The mineralization process of the deposit is divided into three stages: Stage I: Pyrite–Quartz Stage; Stage II: Sulfide–Quartz Stage; Stage III: Quartz–Manganese Carbonate Stage. This paper discusses the ore-forming fluids, ore-forming materials, and deposit genesis of the Erentaolegai silver deposits using fluid inclusions microthermometry, laser Raman spectroscopy, and H-O-S isotope analyses. Fluid inclusion microthermometry and laser Raman spectroscopy analyses indicate that the Erentaolegai silver deposit contains exclusively fluid-rich two-phase fluid inclusions, all of which belong to the H₂O-NaCl system. Homogenization temperatures of fluid inclusions in the three stages (from early to late) ranged from 257 to 311 °C, 228 to 280 °C, and 194 to 238 °C, corresponding to salinities of 1.91 to 7.86 wt%, 2.07 to 5.41 wt%, and 0.70–3.55 wt% NaCl equivalent, densities of 0.75 to 0.83 g/cm⁻³, 0.80 to 0.86 g/cm⁻³ and 0.85 to 0.89 g/cm⁻³. The mineralization pressure ranged from 12.2 to 29.5 MPa, and the mineralization depth was 0.41 to 0.98 km, indicating low-pressure and shallow-depth mineralization conditions. H-O isotope results indicate that the ore-forming fluid is a mixture of magmatic fluids and meteoric water, with meteoric contribution dominating in the late stage. The δ³⁴S values of metallic sulfides ranged from −1.8 to +4.0‰, indicating that the metallogenic material of the Erentaolegai silver deposit was dominated by a deep magmatic source. This study concludes that meteoric water mixing and subsequent fluid cooling served as the primary mechanism for silver mineral precipitation. The Erentaolegai silver deposit is classified as a low-sulfidation epithermal silver deposit. Full article

(This article belongs to the Special Issue Recent Developments in Rare Metal Mineral Deposits)

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33 pages, 167102 KiB

Open AccessArticle

Influence of Mineralogical and Petrographic Properties on the Mechanical Behavior of Granitic and Mafic Rocks

by Muhammad Faisal Waqar, Songfeng Guo, Shengwen Qi, Malik Aoun Murtaza Karim, Khan Zada, Izhar Ahmed and Yanjun Shang

Minerals 2025, 15(7), 747; https://doi.org/10.3390/min15070747 - 17 Jul 2025

Viewed by 411

Abstract

This study investigates the impact of mineralogical and petrographic characteristics on the mechanical behavior of granitic and mafic rocks from the Shuangjiangkou (Sichuan Province) and Damiao complexes (Hebei Province) in China. The research methodology combined petrographic investigation, comprising optical microscopy and Scanning Electron [...] Read more.

This study investigates the impact of mineralogical and petrographic characteristics on the mechanical behavior of granitic and mafic rocks from the Shuangjiangkou (Sichuan Province) and Damiao complexes (Hebei Province) in China. The research methodology combined petrographic investigation, comprising optical microscopy and Scanning Electron Microscopy–Energy-Dispersive X-ray Spectroscopy (SEM-EDS) methods, with methodical geotechnical characterization to establish quantitative relationships between mineralogical composition and engineering properties. The petrographic studies revealed three lithologic groups: fine-to-medium-grained Shuangjiangkou granite (45%–60% feldspar, 27%–35% quartz, 10%–15% mica), plagioclase-rich anorthosite (more than 90% of plagioclase), and intermediate mangerite (40%–50% of plagioclase, 25%–35% of perthite). The uniaxial compressive strength tests showed great variations: granite (127.53 ± 15.07 MPa), anorthosite (167.81 ± 23.45 MPa), and mangerite (205.12 ± 23.87 MPa). Physical properties demonstrated inverse correlations between mechanical strength and both water absorption (granite: 0.25%–0.42%; anorthosite: 0.07%–0.44%; mangerite: 0.10%–0.25%) and apparent porosity (granite: 0.75%–0.92%; anorthosite: 0.20%–1.20%; mangerite: 0.29%–0.69%), with positive correlations to specific gravity (granite: 1.88–3.03; anorthosite: 2.67–2.90; mangerite: 2.43–2.99). Critical petrographic features controlling mechanical behavior include the following: (1) mica content in granite creating anisotropic properties, (2) extensive feldspar alteration through sericitization increasing microporosity and reducing intergranular cohesion, (3) plagioclase micro-fracturing and alteration to clinozoisite–sericite assemblages in anorthosite creating weakness networks, and (4) mangerite’s superior composition of >95% hard minerals with minimal sheet mineral content and limited alteration. Failure mode analysis indicated distinct patterns: granite experiencing shear-dominated failure (30–45° diagonal planes), anorthosite demonstrated tensile fracturing with vertical splitting, and mangerite showed catastrophic brittle failure with extensive fracture networks. These findings provide quantitative frameworks that relate petrographic features to engineering behavior, offering valuable insights for rock mass assessment and engineering design in similar crystalline rock terrains. Full article

(This article belongs to the Special Issue Characterization of Geological Material at Nano- and Micro-scales)

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15 pages, 588 KiB

Open AccessReview

Archaeometry of Ancient Mortar-Based Materials in Roman Regio X and Neighboring Territories: A First Review

by Simone Dilaria

Minerals 2025, 15(7), 746; https://doi.org/10.3390/min15070746 - 16 Jul 2025

Viewed by 440

Abstract

This review synthesizes the corpus of archaeometric and analytical investigations focused on mortar-based materials, including wall paintings, plasters, and concrete, in the Roman Regio X and neighboring territories of northeastern Italy from the mid-1970s to the present. Organized into three principal categories—wall paintings [...] Read more.

This review synthesizes the corpus of archaeometric and analytical investigations focused on mortar-based materials, including wall paintings, plasters, and concrete, in the Roman Regio X and neighboring territories of northeastern Italy from the mid-1970s to the present. Organized into three principal categories—wall paintings and pigments, structural and foundational mortars, and flooring preparations—the analysis highlights the main methodological advances and progress in petrographic microscopy, mineralogical analysis, and mechanical testing of ancient mortars. Despite extensive case studies, the review identifies a critical need for systematic, statistically robust, and chronologically anchored datasets to fully reconstruct socio-economic and technological landscapes of this provincial region. This work offers a programmatic research agenda aimed at bridging current gaps and fostering integrated understandings of ancient construction technologies in northern Italy. The full forms of the abbreviations used throughout the text to describe the analytical equipment are provided at the end of the document in the “Abbreviations” section. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Insights into Cultural Heritage Materials)

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17 pages, 2832 KiB

Open AccessArticle

Performance and Microstructural Evolution of One-Part Alkali-Activated Cement in Tailings Stabilization

by Nilo Cesar Consoli, Fernanda Maria Jaskulski, Taciane Pedrotti Fracaro, Giovani Jordi Bruschi, Suéllen Tonatto Ferrazzo, Mariana Tonini de Araújo, Andres Mauricio Lotero Caicedo and João Paulo de Sousa Silva

Minerals 2025, 15(7), 745; https://doi.org/10.3390/min15070745 - 16 Jul 2025

Viewed by 325

Abstract

This paper explores the role of one-part alkali-activated cement, utilizing metakaolin as a precursor, in the long-term stabilization of mining tailings. Investigating three key factors (Si/Al and Na/Si ratios and curing period), this study reveals insights into the mechanical performance and microstructure of [...] Read more.

This paper explores the role of one-part alkali-activated cement, utilizing metakaolin as a precursor, in the long-term stabilization of mining tailings. Investigating three key factors (Si/Al and Na/Si ratios and curing period), this study reveals insights into the mechanical performance and microstructure of alkali-activated cemented iron ore tailings. Unconfined compressive strength test, statistical analysis, and Scanning Electron Microscopy analysis with Energy Dispersive Spectroscopy were performed. Findings indicate that the Si/Al ratio significantly influences strength, with an optimal ratio of 3.5. The Na/Si ratio introduces complexity, affecting alkali availability and reactivity, leading to nuanced strength variations. Extended curing periods consistently enhance the strength of alkali-activated cement, highlighting its dynamic nature. Notably, the 7-day specimens exhibit a less homogeneous distribution, weaker bonding, and decreased structural integrity compared to their 60-day counterparts. This research underscores the intricate nature of alkali-activated cement hydration, emphasizing the interdependence of Si/Al and Na/Si ratios. The observed strengthening effect with prolonged curing suggests the potential for tailoring these materials to specific applications. Addressing a research gap, especially in applying alkali-activation to mining tailings stabilization, this study highlights metakaolin’s role as a suitable precursor. Full article

(This article belongs to the Special Issue Green Mining Solutions for the Sustainability of Mine Tailings Management)

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19 pages, 13286 KiB

Open AccessArticle

Differential Evolutionary Mechanisms of Tight Sandstone Reservoirs and Their Influence on Reservoir Quality: A Case Study of Carboniferous–Permian Sandstones in the Shenfu Area, Ordos Basin, China

by Xiangdong Gao, You Guo, Hui Guo, Hao Sun, Xiang Wu, Mingda Zhang, Xirui Liu and Jiawen Deng

Minerals 2025, 15(7), 744; https://doi.org/10.3390/min15070744 - 16 Jul 2025

Viewed by 190

Abstract

The Carboniferous–Permian tight sandstone gas reservoirs in the Shenfu area of the Ordos Basin in China are characterized by the widespread development of multiple formations. However, significant differences exist among the tight sandstones of different formations, and their formation mechanisms and key controlling [...] Read more.

The Carboniferous–Permian tight sandstone gas reservoirs in the Shenfu area of the Ordos Basin in China are characterized by the widespread development of multiple formations. However, significant differences exist among the tight sandstones of different formations, and their formation mechanisms and key controlling factors remain unclear, hindering the effective selection and development of favorable tight gas intervals in the study area. Through comprehensive analysis of casting thin section (CTS), scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), particle size and sorting, porosity and permeability data from Upper Paleozoic tight sandstone samples, combined with insights into depositional environments, burial history, and chemical reaction processes, this study clarifies the characteristics of tight sandstone reservoirs, reveals the key controlling factors of reservoir quality, confirms the differential evolutionary mechanisms of tight sandstone of different formations, reconstructs the diagenetic sequence, and constructs an evolution model of reservoir minerals and porosity. The research results indicate depositional processes laid the foundation for the original reservoir properties. Sandstones deposited in tidal flat and deltaic environments exhibit superior initial reservoir qualities. Compaction is a critical factor leading to the decline in reservoir quality across all formations. However, rigid particles such as quartz can partially mitigate the pore reduction caused by compaction. Early diagenetic carbonate cementation reduces reservoir quality by occupying primary pores and hindering the generation of secondary porosity induced by acidic fluids, while later-formed carbonate further densifies the sandstone by filling secondary intragranular pores. Clay mineral cements diminish reservoir porosity and permeability by filling intergranular and intragranular pores. The Shanxi and Taiyuan Formations display relatively poorer reservoir quality due to intense illitization. Overall, the reservoir quality of Benxi Formation is the best, followed by Xiashihezi Formation, with the Taiyuan and Shanxi Formations exhibiting comparatively lower qualities. Full article

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

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17 pages, 2884 KiB

Open AccessArticle

Dynamic System Roughening from Mineral to Tectonic Plate Scale: Similarities Between Stylolites and Mid-Ocean Ridges

by Daniel Hafermaas, Saskia Köhler, Daniel Koehn and Renaud Toussaint

Minerals 2025, 15(7), 743; https://doi.org/10.3390/min15070743 - 16 Jul 2025

Viewed by 271

Abstract

Stylolites are a common mineral dissolution feature in rocks that develop during compression and form distinct tooth structures. On a tectonic plate scale, mid-ocean ridges (MORs) and transform faults are a significant feature of the Earth’s surface that develop due to accretion of [...] Read more.

Stylolites are a common mineral dissolution feature in rocks that develop during compression and form distinct tooth structures. On a tectonic plate scale, mid-ocean ridges (MORs) and transform faults are a significant feature of the Earth’s surface that develop due to accretion of new material in an extensional regime. We present a comparison between the two features and argue that transform faults in MOR are similar to the sides of stylolite teeth, with both features representing kinematic faults (KFs). First, we present a numerical model of both stylolite and MOR growth and show that in both cases, KFs nucleate and grow spontaneously. In addition, we use a well-established technique (Family–Vicsek scaling) of describing fractal self-affine interfaces, which has been used for stylolites, to characterize the pattern of MOR systems in both simulations and natural examples. Our results show that stylolites and MOR have self-affine scaling characteristics with similar scaling regimes. They both show a larger roughness exponent at the small scale, a smaller exponent at the intermediate scale, followed by a flattening of the system at the largest scale. For stylolites, the physical forces behind the scaling are the surface energy at the small mineral scale, the elastic energy at the intermediate scale, followed by the system reaching the correlation length where growth stops. For MORs, the physical forces behind the scaling are not yet clear; however, the self-affine scaling shows that transform faults at MORs do not have a preferred spacing, but that the spacing is fractal. Our study offers a new perspective on the study of natural roughening phenomena on various scales, from minerals to tectonic plates, and a new view on the development of MORs. Full article

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21 pages, 8925 KiB

Open AccessArticle

Zr-Th-REE Mineralization Associated with Albite–Aegirine-Bearing Rocks of the Burpala Alkaline Intrusion (North Baikal Region, South Margin of the Siberian Craton)

by Ivan Aleksandrovich Izbrodin, Anna Gennadievna Doroshkevich, Anastasia Evgenyevna Starikova, Alexandra Vladislavovna Malyutina, Tatyana Nikolaevna Moroz and Igor Sergeevich Sharygin

Minerals 2025, 15(7), 742; https://doi.org/10.3390/min15070742 - 16 Jul 2025

Viewed by 337

Abstract

The rocks of the Burpala alkaline intrusion contain a wide range of rare minerals that concentrate rare earth elements (REEs), Nb, Th, Li, and other incompatible elements. One of the examples of the occurrence of such mineralization is albite–aegirine rocks located at the [...] Read more.

The rocks of the Burpala alkaline intrusion contain a wide range of rare minerals that concentrate rare earth elements (REEs), Nb, Th, Li, and other incompatible elements. One of the examples of the occurrence of such mineralization is albite–aegirine rocks located at the contact zone between the intrusion and the host terrigenous–sedimentary rock. In albite–aegirine rocks, cubic crystals of “metaloparite”, partially or completely substituted by bastnäsite-(Ce) and polymorphic TiO₂ phases (anatase and rutile) mainly represent the rare metal minerals. In albite–aegirine rocks, trace element minerals are predominantly represented by cubic crystals of “metaloparite”, which are partially or completely replaced by bastnäsite-(Ce) and polymorphic TiO₂ phases such as anatase and rutile. Additionally, Th-bearing zircon (up to 17.7 wt% ThO₂) and a variety of unidentified minerals containing REEs, Th, and Nb were detected. The obtained data indicate that bastnäsite-(Ce) is the result of the recrystallization of “metaloparite” accompanied by the formation of Th-bearing zircon and Nb-bearing rutile (up to 9.9 wt% Nb₂O₅) and the separation of various undiagnosed, unidentified LREE phases. Our studies show that remobilization of LREEs, HFSEs, and local enrichment of rocks in these elements occurred due to the effects of residual fluid enriched in fluorine and carbon dioxide. Full article

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

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30 pages, 7220 KiB

Open AccessArticle

Automated Hyperspectral Ore–Waste Discrimination for a Gold Mine: Comparative Study of Data-Driven and Knowledge-Based Approaches in Laboratory and Field Environments

by Mehdi Abdolmaleki, Saleh Ghadernejad and Kamran Esmaeili

Minerals 2025, 15(7), 741; https://doi.org/10.3390/min15070741 - 16 Jul 2025

Viewed by 531

Abstract

Hyperspectral imaging has been increasingly used in mining for detailed mineral characterization and enhanced ore–waste discrimination, which is essential for optimizing resource extraction. However, the full deployment of this technology still faces challenges due to the variability of field conditions and the spectral [...] Read more.

Hyperspectral imaging has been increasingly used in mining for detailed mineral characterization and enhanced ore–waste discrimination, which is essential for optimizing resource extraction. However, the full deployment of this technology still faces challenges due to the variability of field conditions and the spectral complexity inherent in real-world mining environments. In this study, we compare the performance of two approaches for ore–waste discrimination in both laboratory and actual mine site conditions: (i) a data-driven feature extraction (FE) method and (ii) a knowledge-based mineral mapping method. Rock samples, including ore and waste from an open-pit gold mine, were obtained and scanned using a hyperspectral imaging system under laboratory conditions. The FE method, which quantifies the frequency absorption peaks at different wavelengths for a given rock sample, was used to train three discriminative models using the random forest classifier (RFC), support vector classification (SVC), and K-nearest neighbor classifier (KNNC) algorithms, with RFC achieving the highest performance with an F1-score of 0.95 for the laboratory data. The mineral mapping method, which quantifies the presence of pyrite, calcite, and potassium feldspar based on prior geochemical analysis, yielded an F1-score of 0.78 for the ore class using the RFC algorithm. In the next step, the performance of the developed discriminative models was tested using hyperspectral data of two muck piles scanned in the open-pit gold mine. The results demonstrated the robustness of the mineral mapping method under field conditions compared to the FE method. These results highlight hyperspectral imaging as a valuable tool for improving ore-sorting efficiency in mining operations. Full article

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

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29 pages, 27846 KiB

Open AccessReview

Recycling and Mineral Evolution of Multi-Industrial Solid Waste in Green and Low-Carbon Cement: A Review

by Zishu Yue and Wei Zhang

Minerals 2025, 15(7), 740; https://doi.org/10.3390/min15070740 - 15 Jul 2025

Viewed by 357

Abstract

The accelerated industrialization in China has precipitated a dramatic surge in solid waste generation, causing severe land resource depletion and posing substantial environmental contamination risks. Simultaneously, the cement industry has become characterized by the intensive consumption of natural resources and high carbon emissions. [...] Read more.

The accelerated industrialization in China has precipitated a dramatic surge in solid waste generation, causing severe land resource depletion and posing substantial environmental contamination risks. Simultaneously, the cement industry has become characterized by the intensive consumption of natural resources and high carbon emissions. This review aims to investigate the current technological advances in utilizing industrial solid waste for cement production, with a focus on promoting resource recycling, phase transformations during hydration, and environmental management. The feasibility of incorporating coal-based solid waste, metallurgical slags, tailings, industrial byproduct gypsum, and municipal solid waste incineration into active mixed material for cement is discussed. This waste is utilized by replacing conventional raw materials or serving as active mixed material due to their content of oxygenated salt minerals and oxide minerals. The results indicate that the formation of hydration products can be increased, the mechanical strength of cement can be improved, and a notable reduction in CO₂ emissions can be achieved through the appropriate selection and proportioning of mineral components in industrial solid waste. Further research is recommended to explore the synergistic effects of multi-waste combinations and to develop economically efficient pretreatment methods, with an emphasis on balancing the strength, durability, and environmental performance of cement. This study provides practical insights into the environmentally friendly and efficient recycling of industrial solid waste and supports the realization of carbon peak and carbon neutrality goals. Full article

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

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19 pages, 2991 KiB

Open AccessArticle

Reassessment of Heavy Metal Adsorption Performance in Halloysite Clay Nanotubes: Geographical Variation and Structure–Activity Relationship

by Ying Li, Xingzhong Yuan, Xiuying Wei and Yao Long

Minerals 2025, 15(7), 739; https://doi.org/10.3390/min15070739 - 15 Jul 2025

Viewed by 373

Abstract

Halloysite nanotubes, a naturally occurring nanomaterial with a unique tubular morphology, have shown considerable potential for heavy metal remediation. However, significant inconsistencies in the reported maximum adsorption capacities (q_max) for heavy metal ions—such as Pb²⁺, which ranges from [...] Read more.

Halloysite nanotubes, a naturally occurring nanomaterial with a unique tubular morphology, have shown considerable potential for heavy metal remediation. However, significant inconsistencies in the reported maximum adsorption capacities (q_max) for heavy metal ions—such as Pb²⁺, which ranges from 7.5 to 84.0 mg/g with a coefficient of variation (CV) of 68%—have severely hindered both scientific understanding and practical application of this promising material. To address this critical knowledge gap, we conducted a reassessment using carefully selected halloysite specimens from three geologically distinct deposits (Utah, USA; Henan and Yunnan, China). Under rigorously controlled experimental conditions, we precisely quantified the adsorption capacities of halloysite for Cd²⁺, Zn²⁺, and Pb²⁺. Through an integrated multi-technique characterization approach involving XRF, XRD, FTIR, TEM, and BET analyses, we identified two fundamental crystallochemical parameters that govern the adsorption performance of halloysite: the degree of lattice substitution and the density of surface hydroxyl groups. Our findings reveal that optimal heavy metal adsorption occurs in halloysite with lower lattice substitution and higher surface hydroxyl density. This work not only provides a reliable range of adsorption capacities for halloysite but, more importantly, establishes a scientific foundation for optimizing the application of halloysite in heavy metal remediation. Full article

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

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15 pages, 8577 KiB

Open AccessArticle

Shear Wave Velocity Estimation for Shale with Preferred Orientation Clay Minerals

by Bing Zhang, Cai Liu, Zhiqing Yang, Yao Qin and Mingxing Li

Minerals 2025, 15(7), 738; https://doi.org/10.3390/min15070738 - 15 Jul 2025

Viewed by 217

Abstract

Accurate shear wave velocity is important for shale reservoir exploration and characterization. However, the effect of the ubiquitous preferred orientation of clay minerals on the velocities of shale has rarely been considered in existing S-wave velocity estimation methods, resulting in limited accuracy of [...] Read more.

Accurate shear wave velocity is important for shale reservoir exploration and characterization. However, the effect of the ubiquitous preferred orientation of clay minerals on the velocities of shale has rarely been considered in existing S-wave velocity estimation methods, resulting in limited accuracy of the estimation method. In this study, a S-wave velocity estimation method is proposed for shale while considering the effect of the preferred orientation of clay. First, a compaction model is built by taking the effects of the orientation distribution of clay and the aspect ratio of pores into account. Then, the compaction model is utilized in a workflow to obtain the model parameters by fitting the estimated P-wave velocity with the bedding-normal P-wave velocity from well logging. Finally, the S-wave velocity is estimated using the compaction model and calculated model parameters. The proposed method is verified by laboratory data and successfully applied to a shale gas reservoir. The result shows that the root mean square error almost halves compared with the Xu–White model. Additionally, the correlation coefficient also improves. The improvement in S-wave velocity estimation indicates that the effect of the preferred orientation of clay on the velocities of shale is effectively corrected. The proposed method improves the accuracy of velocity modeling and reservoir characterization for shale. Full article

(This article belongs to the Topic Reservoir Characteristics and Evolution Mechanisms of the Shale)

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18 pages, 12550 KiB

Open AccessArticle

Rare Metal (Li–Ta–Nb) Mineralization and Age of the Kvartsevoye Pegmatite Deposit (Eastern Kazakhstan)

by Tatyana A. Oitseva, Sergey V. Khromykh, Anna V. Naryzhnova, Pavel D. Kotler, Marina A. Mizernaya, Oxana N. Kuzmina and Artem K. Dremov

Minerals 2025, 15(7), 737; https://doi.org/10.3390/min15070737 - 15 Jul 2025

Viewed by 325

Abstract

The Kalba–Narym metallogenic belt is located in East Kazakhstan, which displays rare metal mineralization. The Kvartsevoye rare metal Li–Ta–Nb deposit is located in the north-western ore district. This study presents the results of geological, mineralogical, geochemical, and geochronological analyses of rare metal granite [...] Read more.

The Kalba–Narym metallogenic belt is located in East Kazakhstan, which displays rare metal mineralization. The Kvartsevoye rare metal Li–Ta–Nb deposit is located in the north-western ore district. This study presents the results of geological, mineralogical, geochemical, and geochronological analyses of rare metal granite pegmatites. Rare metal mineralization belongs to a field of variably differentiated pegmatites, including barren, quartz–albite–muscovite, muscovite, and muscovite–quartz–albite microcline mineral associations. This study established that the rare metal mineralization is localized in the quartz–albite–muscovite zone. The main concentrator minerals of rare metals are spodumene for Li and tantalite–columbite for Ta and Nb. Ar/Ar dating of the muscovite allowed us to establish the age of mineralization during the period of 288–285 Ma. The present study enabled the linkage of rare metal mineralization with the differentiation processes of the granites of the Kalba complex. Full article

(This article belongs to the Special Issue Pegmatites as Hosts of Critical Metals: From Petrogenesis to Mineral Exploration)

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29 pages, 14630 KiB

Open AccessArticle

Tectonic Evolution of the Eastern Central Asian Orogenic Belt: Evidence from Magmatic Activity in the Faku Area, Northern Liaoning, China

by Shaoshan Shi, Yi Shi, Xiaofan Zhou, Nan Ju, Yanfei Zhang and Shan Jiang

Minerals 2025, 15(7), 736; https://doi.org/10.3390/min15070736 - 15 Jul 2025

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Abstract

The Permian–Triassic magmatic record in the eastern Central Asian Orogenic Belt (CAOB) provides critical insights into the terminal stages of the Paleo-Asian Ocean (PAO) evolution, including collisional and post-collisional processes following its Late Permian closure. The northeastern China region, tectonically situated within the [...] Read more.

The Permian–Triassic magmatic record in the eastern Central Asian Orogenic Belt (CAOB) provides critical insights into the terminal stages of the Paleo-Asian Ocean (PAO) evolution, including collisional and post-collisional processes following its Late Permian closure. The northeastern China region, tectonically situated within the eastern segment of the CAOB, is traditionally known as the Xingmeng Orogenic Belt (XOR). This study integrates zircon U-Pb geochronology, whole-rock geochemistry, and zircon Hf isotopic analyses of intermediate-acid volcanic rocks and intrusive rocks from the former “Tongjiatun Formation” in the Faku area of northern Liaoning. The main objective is to explore the petrogenesis of these igneous rocks and their implications for the regional tectonic setting. Zircon U-Pb ages of these rocks range from 260.5 to 230.1 Ma, indicating Permian–Triassic magmatism. Specifically, the Gongzhuling rhyolite (260.5 ± 2.2 Ma) and Gongzhuling dacite (260.3 ± 2.4 Ma) formed during the Middle-Late Permian (270–256 Ma); the Wangjiadian dacite (243 ± 3.0 Ma) and Wafangxi rhyolite (243.9 ± 3.0 Ma) were formed in the late Permian-early Middle Triassic (256–242 Ma); the Haoguantun rhyolite (240.9 ± 2.2 Ma) and Sheshangou pluton (230.1 ± 1.7 Ma) were formed during the Late Middle-Late Triassic (241–215 Ma). Geochemical studies, integrated with the geochronological results, reveal distinct tectonic settings during successive stages: (1) Middle-Late Permian (270–256 Ma): Magmatism included peraluminous A-type rhyolite with in calc-alkaline series (e.g., Gongzhuling) formed in an extensional environment linked to a mantle plume, alongside metaluminous, calc-alkaline I-type dacite (e.g., Gongzhuling) associated with the subduction of the PAO plate. (2) Late Permian-Early Middle Triassic (256–242 Ma): Calc-alkaline I-type magmatism dominated, represented by dacite (e.g., Wangjiadian) and rhyolite (e.g., Wafangxi), indicative of a collisional uplift environment. (3) Late Middle-Late Triassic (241–215 Ma): Magmatism transitioned to high-K calc-alkaline with A-type rocks affinities, including rhyolite (e.g., Haoguantun) and plutons (e.g., Sheshangou), formed in a post-collisional extensional environment. This study suggests that the closure of the PAO along the northern margin of the North China Craton (NCC) occurred before the Late Triassic. Late Triassic magmatic rocks in this region record a post-orogenic extensional setting, reflecting tectonic processes following NCC-XOR collision rather than PAO subduction. Combined with previously reported age data, the tectonic evolution of the eastern segment of the CAOB during the Permian-Triassic can be divided into four stages: active continental margin (293–274 Ma), plate disintegration (270–256 Ma), final collision and closure (256–241 Ma), and post-orogenic extension (241–215 Ma). Full article

(This article belongs to the Special Issue Selected Papers from the 7th National Youth Geological Congress)

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