Minerals

18 pages, 1896 KB

Open AccessArticle

Mycelial_Net: A Bio-Inspired Deep Learning Framework for Mineral Classification in Thin Section Microscopy

by Paolo Dell’Aversana

Minerals 2025, 15(11), 1112; https://doi.org/10.3390/min15111112 (registering DOI) - 25 Oct 2025

This study presents the application of Mycelial_Net, a biologically inspired deep learning architecture, to the analysis and classification of mineral images in thin section under optical microscopy. The model, inspired by the adaptive connectivity of fungal mycelium networks, was trained on a test [...] Read more.

This study presents the application of Mycelial_Net, a biologically inspired deep learning architecture, to the analysis and classification of mineral images in thin section under optical microscopy. The model, inspired by the adaptive connectivity of fungal mycelium networks, was trained on a test mineral image database to extract structural features and to classify various minerals. The performance of Mycelial_Net was evaluated in terms of accuracy, robustness, and adaptability, and compared against conventional convolutional neural networks. The results demonstrate that Mycelial_Net, properly integrated with Residual Networks (ResNets), offers superior analysis capabilities, interpretability, and resilience to noise and artifacts in petrographic images. This approach holds promise for advancing automated mineral identification and geological analysis through adaptive AI systems. Full article

(This article belongs to the Special Issue Application of Machine Learning in Mining, Mineral Processing and Extractive Metallurgy)

18 pages, 16558 KB

Open AccessArticle

Study on the Influence Mechanism of Particle Migration on the Stability of Weathering Crust Elution-Deposited Rare Earth Ores

by Ke Xiao, Zhenyue Zhang, Defeng Liu, Wenda Guo, Zhuo Chen and Ruan Chi

Minerals 2025, 15(11), 1111; https://doi.org/10.3390/min15111111 (registering DOI) - 25 Oct 2025

Abstract

Particle migration can affect the ore bodies stability of weathering crust elution-deposited rare earth ores during leaching. It may trigger geological disasters such as landslides. Therefore, direct shear tests, microstructure characterization tests, and numerical simulation tests were adopted. The mechanical behavior characteristics of [...] Read more.

Particle migration can affect the ore bodies stability of weathering crust elution-deposited rare earth ores during leaching. It may trigger geological disasters such as landslides. Therefore, direct shear tests, microstructure characterization tests, and numerical simulation tests were adopted. The mechanical behavior characteristics of ore samples with different burial depths were explored. Simultaneously, the evolution characteristics of their microstructure, mineral composition, and failure modes were also studied. The results showed that after leaching, the cohesion (c) initially rose and then dropped as the proportion of −0.075 mm particles increased. The internal friction angle (φ) initially dropped, then increased, and finally stabilized. When its proportion was greater than 20%, the c of the middle-upper part of the ore sample was greater than that of the upper part. Meanwhile, the φ was smaller than that of the upper part. Especially when its proportion was greater than 30%, the c increased gradually with depth. XRD analysis revealed that illite and kaolinite were the main mineral components for the fine particle migration. Simulation experiment results revealed that in ore samples with 10% fine particles, there was noticeable migration and deposition in the upper part. However, it was the least in the upper middle and lower parts. Contact number and coordination number sharply decreased with depth, then increased, and finally gradually reduced. As deposition increased, the shear zone tilt angle grew larger. More secondary shear zones formed. The cracks became more evenly distributed. Full article

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

21 pages, 1990 KB

Open AccessArticle

Heavy Metal Adsorption and Desorption Behavior of Raw Sepiolite: A Study on Cd(II), Cu(II), and Ni(II) Ions

by Anna Bourliva

Minerals 2025, 15(11), 1110; https://doi.org/10.3390/min15111110 (registering DOI) - 25 Oct 2025

Abstract

This study investigates the adsorption behavior of natural sepiolite for the removal of cadmium (Cd²⁺), copper (Cu²⁺), and nickel (Ni²⁺) ions from aqueous solutions under batch conditions. The sepiolite was extensively characterized prior to adsorption experiments. Mineralogical [...] Read more.

This study investigates the adsorption behavior of natural sepiolite for the removal of cadmium (Cd²⁺), copper (Cu²⁺), and nickel (Ni²⁺) ions from aqueous solutions under batch conditions. The sepiolite was extensively characterized prior to adsorption experiments. Mineralogical analysis confirmed the presence of crystalline sepiolite, while DTG-TGA revealed thermal stability with distinct weight loss linked to surface and structural water. BET analysis indicated a high surface area of 194 m²/g and a mesoporous structure favorable for adsorption. Batch experiments evaluated the effects of contact time, pH, adsorbent dosage, and initial metal concentration. Adsorption was highly pH-dependent, with maximum removal near-neutral pH values. Higher adsorbent dosages reduced in a lower adsorption capacity per unit mass, primarily because the fixed amount of solute was distributed over a larger number of available sites, leading to unsaturation of the adsorbent surface and possible particle agglomeration. Isotherm modeling revealed that the Langmuir model provided the best fit, indicating monolayer adsorption with maximum adsorption capacities of 15.95 mg/g for Cd(II), 37.31 mg/g for Cu(II), and 17.83 mg/g for Ni(II). Langmuir constants indicated favorable interactions. Kinetics showed rapid adsorption within the first hour, reaching equilibrium at 240 min through surface adsorption and intraparticle diffusion. Cu(II) exhibited the fastest uptake, while Ni(II) adsorbed more slowly, suggesting differences in diffusion rates among the metal ions. Desorption using 0.1 N HCl achieved over 80% efficiency for all metals, confirming sepiolite reusability. Overall, raw sepiolite is an effective, low-cost adsorbent for removing potentially toxic elements from water. Full article

(This article belongs to the Special Issue Applications of Clay Minerals and Engineered Materials in Water and Wastewater Treatment)

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26 pages, 18963 KB

Open AccessArticle

Mineralogical and Geochemical Evolution During Limestone Weathering and Pedogenesis in Shimen, Hunan Province, South China

by Qi Chen, Jianlan Luo, Fengchu Liao, Xuesheng Xu, Aili Li, Liran Chen, Tuo Zhao, Tingmao Long, Suxin Li and Huan Li

Minerals 2025, 15(11), 1109; https://doi.org/10.3390/min15111109 (registering DOI) - 25 Oct 2025

Abstract

Understanding mineralogical transformations and elemental mobility during limestone weathering is critical for deciphering carbon cycling and critical zone evolution in karst terrains. This study investigates an in situ limestone weathering profile (12.6 m depth) in Shimen, Hunan Province, using integrated mineralogical (XRD, EPMA-EDS), [...] Read more.

Understanding mineralogical transformations and elemental mobility during limestone weathering is critical for deciphering carbon cycling and critical zone evolution in karst terrains. This study investigates an in situ limestone weathering profile (12.6 m depth) in Shimen, Hunan Province, using integrated mineralogical (XRD, EPMA-EDS), elemental (XRF, ICP-MS), and Sr isotopic (MC-ICP-MS) analyses. Results reveal a two-stage pedogenic model: (1) Rapid dissolution of primary calcite (>95 wt% in bedrock to 1.1–48.5 wt% in soil) creates an abrupt bedrock–soil interface via volumetric collapse (>90%), accumulating acid-insoluble residues (quartz-dominated); (2) Subsequent weathering drives illitization of K-feldspar, trace element enrichment (e.g., Ni, Tl, Th τ up to 180) via illite adsorption, and radiogenic ⁸⁷Sr/⁸⁶Sr evolution (0.7076 in bedrock to 0.7292 in soil). Depth-dependent increases in chemical index of alteration (CIA: 6.79–79.96) and mass transfer coefficients confirm progressive weathering intensity. The profile acts as a net carbon source (58.5% depletion in soil inorganic carbon), highlighting significant CO₂ release during pedogenesis. These findings provide mechanistic insights into subtropical critical zone evolution and element cycling in carbonate-dominated systems. Full article

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

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17 pages, 1050 KB

Open AccessArticle

Application of Jigging Beneficiation for Processing of Waste from Post-Mining Heaps for Circular Economy Purposes

by Daniel Kowol, Piotr Matusiak, Rafał Baron, Paweł Friebe, Sebastian Jendrysik, Joanna Bigda, Agata Czardybon and Karina Ignasiak

Minerals 2025, 15(11), 1108; https://doi.org/10.3390/min15111108 (registering DOI) - 24 Oct 2025

Abstract

The article presents the results of research and development work conducted as part of the H2GEO project, aimed at creating a comprehensive technology for the processing of post-mining coal waste heaps. The core of the solution is a mobile density separation system based [...] Read more.

The article presents the results of research and development work conducted as part of the H2GEO project, aimed at creating a comprehensive technology for the processing of post-mining coal waste heaps. The core of the solution is a mobile density separation system based on a pulsating jig, enabling effective recovery of carbonaceous and mineral fractions. Laboratory experiments assessed the impact of key process parameters—such as sieve slot size, pulsation frequency, and enrichment time—on the efficiency and accuracy of separation for different grain size classes. The most favorable results were obtained using a 2.5 mm screen, a pulsation frequency of 60 min⁻¹, and extended enrichment time, which ensured high-quality separation and low ash content in the carbon-bearing product. The findings supported the design of a new industrial separator (jig) equipped with advanced control systems, facilitating the production of homogeneous fractions suitable for further processing into hydrogen, geopolymers, and construction materials. The proposed solution aligns with circular economy principles, promoting waste reuse, environmental hazard mitigation, and the revitalization of degraded post-industrial areas. Full article

(This article belongs to the Special Issue Scientific Disposal and Utilization of Coal-Based Solid Waste)

31 pages, 20520 KB

Open AccessArticle

Genesis of the Baijianshan Skarn-Type Zn-Cu Polymetallic Deposit, Chinese Eastern Tianshan: Constraints from Geology, Geochronology and Geochemistry

by Fenwei Cheng, Shuai Zhang, Jianxin Wu, Baofeng Huang and Di Zhang

Minerals 2025, 15(11), 1107; https://doi.org/10.3390/min15111107 - 24 Oct 2025

Abstract

The Baijianshan deposit is the sole skarn Zn-Cu polymetallic deposit in the Xiaoshitouquan ore field, Xinjiang, China. Its ore genesis remains controversial, which hinders understanding of the relationship between skarn-type Zn-Cu and adjacent epithermal Ag-Cu-Pb-Zn mineralization and consequently impedes further regional exploration. LA-ICP-MS [...] Read more.

The Baijianshan deposit is the sole skarn Zn-Cu polymetallic deposit in the Xiaoshitouquan ore field, Xinjiang, China. Its ore genesis remains controversial, which hinders understanding of the relationship between skarn-type Zn-Cu and adjacent epithermal Ag-Cu-Pb-Zn mineralization and consequently impedes further regional exploration. LA-ICP-MS U-Pb dating on zircons from the granite and granite porphyry from the mining area yielded ages of 311 ± 1.7 Ma and 312 ± 1.6 Ma, respectively. The corresponding zircon ε_Hf(t) values and T_DM ages are 8.7–9.9 and 624–555 Ma for the granite, and 7.2–9.9 and 673–552 Ma for the granite porphyry. These granites are metaluminous, high-K calc-alkaline I-type granites, with high LREE/HREE ratios (4.92–9.03) and pronounced negative Eu anomalies. They are enriched in K, Th, U, Zr, and Hf, with significant depletions in Sr, P, and Ti. Combined geological and geochemical evidence indicate that these Late Carboniferous granites were derived from the juvenile crustal and formed in subduction-related back basin. Two-phase aqueous inclusions in the ore-bearing quartz and calcite have homogenization temperatures ranging from 117 to 207 °C and 112 to 160 °C, respectively, with the salinities in the ranges of 0.18~7.17 and 0.53~5.26 wt% NaCl eq. The S and Pb isotopic compositions of sulfides in the ores indicate that the ore-forming metals were sourced from the medium-acidic magmatite. The δ¹⁸O_H2O and δD_H2O values of hydrothermal fluids range from −6.97% to −5.84% and −106.8% to −99.6%, respectively, suggesting that the ore-forming fluids originated from the mixing of magmatic and meteoric water. Fluid mixing and corresponding conductive cooling were identified as the principal mechanism triggering the metallic mineral precipitation. The Baijianshan skarn Zn-Cu polymetallic deposit shares contemporaneous magmatic-mineralization ages and analogous material sources with the epithermal polymetallic deposits in the Xiaoshitouquan ore field, collectively constituting a unified skarn-epithermal metallogenic system. This hypothesis indicates that the deep parts of the epithermal deposits within the Yamansu volcanic rocks possess potential for exploring the porphyry-skarn-type deposits. Full article

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

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27 pages, 12187 KB

Open AccessArticle

Petrophysical Characteristics of Geological Formations of the Zhezkazgan Ore District (Kazakhstan) and Their Relationship with Mineralization

by Lyudmila Issayeva, Sara Istekova, Dina Tolybaeva, Kuanysh Togizov, Zhanibek Saurykov and Aygul Issagaliyeva

Minerals 2025, 15(11), 1106; https://doi.org/10.3390/min15111106 - 23 Oct 2025

Abstract

This work presents a generalization and analysis of the physical properties of rocks and ores from the Zhezkazgan ore district. Studies were carried out to identify general patterns in variations in the magnetic, density, velocity, and electrical parameters of the rocks that make [...] Read more.

This work presents a generalization and analysis of the physical properties of rocks and ores from the Zhezkazgan ore district. Studies were carried out to identify general patterns in variations in the magnetic, density, velocity, and electrical parameters of the rocks that make up the geological section of the region. Based on the physical parameter measurements of the rock samples and drill cores collected in large quantities evenly throughout the region, a spatial analysis and quantitative assessment were conducted for the magnetic susceptibility, density, specific electrical resistivity, polarizability, and seismic velocity of the rocks. These properties were systematized at the level of formations, individual suites, and lithological heterogeneities. Correlations between the physical properties of the rocks, their composition, and the conditions of their formation were established. This study demonstrated the potential of using petrophysical characteristics in tectonic studies, geological mapping, and the identification of the exploration and ore-controlling factors in copper mineralization. It was found that the deposits of the productive horizons of the Zhezkazgan and Taskuduk suites are characterized by consistent physical parameters across the entire area, due to their relative homogeneity in lithological, structural–textural, and other features. The physical parameters of the rocks are influenced by several factors associated with mineralization processes, including changes in the total porosity, structure, and texture of the host rocks, alteration of the original mineral composition of the ores, fragmentation, fracturing, fissuring, and others. The obtained results significantly improve the reliability of geologically interpreting geophysical anomalies, especially in areas covered by loose sediments and where productive horizons are deeply buried. The detailed petrophysical analysis of the region has made it possible to provide recommendations for selecting an optimal set of geophysical methods for further successful work at the prospecting-evaluation and exploration stages in the Zhezkazgan ore district. Full article

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

17 pages, 4535 KB

Open AccessArticle

Petrophysical Characterisation and Suitability of Serpentinites from the Monteferrato Area (Tuscany, Italy) for Architectural Restoration

by Alba P. Santo, Carlo Alberto Garzonio, Elena Pecchioni and Teresa Salvatici

Minerals 2025, 15(11), 1105; https://doi.org/10.3390/min15111105 - 23 Oct 2025

Abstract

This study investigates the mineralogical and physical properties of serpentinite from the Monteferrato area (Tuscany, Italy) to evaluate its potential use in Tuscany architectural restoration. The research addresses the need to identify replacement materials compatible with historic stones while preserving their original features. [...] Read more.

This study investigates the mineralogical and physical properties of serpentinite from the Monteferrato area (Tuscany, Italy) to evaluate its potential use in Tuscany architectural restoration. The research addresses the need to identify replacement materials compatible with historic stones while preserving their original features. Representative specimens from the Bagnolo quarry were analysed through physical testing and a wide range of mineralogical and geochemical techniques, including polarised light microscopy, X-ray diffraction, electron probe micro-analysis, whole-rock chemistry, and fibre quantification. The results show a mineralogical composition dominated by serpentine-group minerals and magnetite, with physical properties generally consistent across samples. Measured capillary water absorption ranges from 3.27 to 5.27 g/m²·s^0.5, open porosity from 5.25% to 8.93%, apparent densities range from 2.49 to 2.56 g/cm³, and imbibition coefficient from 2.16% to 3.71%. Comparative analysis with serpentinite from historic sources (Figline di Prato quarry, Tuscany) and from monuments (Baptistery of San Giovanni, Florence) demonstrates close compositional and textural affinities, supporting the suitability of the rock from the studied quarry for restoration purposes in Tuscany monuments. However, chrysotile concentrations up to 14,153 mg/kg, exceeding Italian regulatory thresholds, represent a critical limitation. This not only requires the implementation of strict safety measures but also raises serious concerns regarding the practical feasibility of using this stone in conservation projects. More broadly, the presence of asbestiform minerals in serpentinites highlights a significant and often underestimated health risk associated with their extraction, processing, and use. Despite its importance, detailed fibre count data are rarely published or made publicly accessible, hindering both transparent risk assessment and informed decision-making. By integrating petrographic, mineralogical, and physical–mechanical characterisation with fibre quantification, this study not only assesses the technical suitability of Monteferrato serpentinites for restoration of Tuscan monuments but also contributes to a more responsible and evidence-based approach to their use, emphasising the urgent need for transparency and health protection in conservation practices. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials, 2nd Edition)

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22 pages, 24589 KB

Open AccessArticle

Genesis of Conventional Reservoirs in Braided Fluvial Tight Sandstones: Evidence from the He 1 Member, Upper Paleozoic, Southern Ordos Basin, China

by Xiaoqi Ding, Yi Wang, Jingyun Gao, Feilan Lin, Xiang Zhang, Shujie Han and Ying Zhu

Minerals 2025, 15(11), 1104; https://doi.org/10.3390/min15111104 - 23 Oct 2025

Abstract

The He 1 Member of the Xiashihezi Formation (Upper Paleozoic) in the Ordos Basin represents typical tight sandstones (Φ < 10%, k < 0.5 mD). However, against the extensive tight sandstone background of the He 1 Member in the southern basin, conventional reservoirs [...] Read more.

The He 1 Member of the Xiashihezi Formation (Upper Paleozoic) in the Ordos Basin represents typical tight sandstones (Φ < 10%, k < 0.5 mD). However, against the extensive tight sandstone background of the He 1 Member in the southern basin, conventional reservoirs (Φ > 12%, K > 1 mD) occur locally. Elucidating the genetic mechanism of these conventional reservoirs is critical for evaluating gas reservoirs in this region. Based on core descriptions and systematic sampling from cored wells, reservoir types are classified according to pore types and porosity in sandstones. Depositional microfacies, petrology, and diagenesis of each reservoir type are then investigated to ultimately elucidate the genetic mechanism of conventional reservoirs. Results demonstrate that intense compaction and quartz overgrowths are the primary controls on the development of the He 1 Member tight sandstones. Alteration of volcanic lithic fragments and volcanic ash matrix generated abundant intragranular dissolution pores and micropores within the matrix, while simultaneously producing substantial illite–smectite mixed-layer clays and chlorite clays. Additionally, this process supplied silica for quartz overgrowths. Moderate amounts of chlorite coatings can inhibit quartz overgrowths, thereby preserving residual intergranular porosity. Conventional reservoirs exhibit low lithic fragment content (<20 vol.%) and are characterized by a porosity assemblage of both intergranular (avg. 2.3%) and intragranular dissolution pores (avg. 6.5%). Their formation requires weak compaction, intense dissolution, and weak quartz overgrowths. These reservoirs develop within high-energy transverse bars that are sealed by overlying and underlying mudstones. Such transverse bars constitute closed intrastratal-diagenetic systems with restricted mass transfer during burial. This study provides a compelling example of diagenetic heterogeneity induced by variations in sandstone architecture within fluvial successions. Full article

(This article belongs to the Special Issue Natural and Induced Diagenesis in Clastic Rock)

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24 pages, 12580 KB

Open AccessArticle

The Early Cretaceous High-Nb Basalt and Arc Andesite Association in the Eastern Segment of the Altyn Tagh Fault: Petrological Records of Intracontinental Extension

by Lu-Qing Qin, Yong Bai, Yu An, Jin-Lin Wang, Ying-Ying Ma, Hai-Xin Lu and Yu-Hang Luo

Minerals 2025, 15(11), 1103; https://doi.org/10.3390/min15111103 - 23 Oct 2025

Abstract

The Altyn Tagh Fault plays a critical role in understanding the tectonic evolution of the northern margin of the Tibetan Plateau. However, considerable debate persists regarding its activity and deformation history. This study investigates volcanic rocks from the Beidayao-Jianquanzi-Hanxia-Hongliuxia area in the eastern [...] Read more.

The Altyn Tagh Fault plays a critical role in understanding the tectonic evolution of the northern margin of the Tibetan Plateau. However, considerable debate persists regarding its activity and deformation history. This study investigates volcanic rocks from the Beidayao-Jianquanzi-Hanxia-Hongliuxia area in the eastern segment of the fault. By employing zircon U-Pb dating, whole-rock geochemistry, and Sr-Nd isotope analysis, we aim to elucidate their petrogenesis and tectonic setting, thereby providing new insights into the crustal evolution of the eastern Altyn Tagh Fault. Zircon U-Pb dating of the Hongliuxia rhyolite yields a weighted mean ²⁰⁶Pb/²³⁸U age of 106.6 ± 0.6 Ma, indicating an Early Cretaceous eruption. Geochemically, the western part of the study area (Beidayao and Jianquanzi) is dominated by basalts that exhibit significant enrichment in large ion lithophile elements and light rare earth elements, together with high Nb concentrations (>20 ppm), as well as high Nb/La (0.64–1.12) and Nb/U (29.8–35.42) ratios, consistent with the characteristics of high-Nb basalt. In contrast, the eastern area (Hanxia and Hongliuxia) is characterized by andesitic rocks that display typical continental arc affinities, marked by enrichment in Th, U, and Pb and depletion in Nb, Ta, and Ti. Isotopically, the basalts show initial ⁸⁷Sr/⁸⁶Sr ratios of 0.706–0.707 and ε_Nd (t) values ranging from −3.2 to 0.8, whereas the andesites possess more radiogenic Sr isotopic compositions, with (⁸⁷Sr/⁸⁶Sr)_i ratios of 0.710–0.717, and more negative ε_Nd (t) values from −11.4 to −1.5, suggesting derivation from an enriched mantle source. Integrating geochemical data with regional geological records, we propose that the eastern part of the Altyn Fault experienced a significant intracontinental extensional setting during the Early Cretaceous, where asthenospheric mantle upwelling played a key role in the generation of the volcanic rocks. This study provides key petrological and geochemical constraints on Early Cretaceous deformation and activity along the Altyn Tagh Fault, and also offers a valuable reference for understanding the evolution of similar fault systems. Full article

(This article belongs to the Special Issue Geochronological, Petrological and Geochemical Studies of Basaltic Rocks from Oceanic Crust)

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29 pages, 9237 KB

Open AccessArticle

Estimating Content of Rare Earth Elements in Marine Sediments Using Hyperspectral Technology: Experiment and Method Series

by Dalong Liu, Shijuan Yan, Gang Yang, Jun Ye, Chunhui Yuan, Mu Huang, Yiping Luo, Yue Hao, Yuxue Zhang, Xiaofeng Liu, Xiangwen Ren, Zhihua Chen and Dewen Du

Minerals 2025, 15(11), 1102; https://doi.org/10.3390/min15111102 - 23 Oct 2025

Abstract

Marine sediments enriched with rare earth elements (REEs) serve as a significant reservoir, particularly for heavy REEs. Conventional lab-based REE exploration restricts rapid and large-scale assessment, whereas hyperspectral imaging provides a promising approach for quantitative evaluation. This study evaluates the capacity of hyperspectral [...] Read more.

Marine sediments enriched with rare earth elements (REEs) serve as a significant reservoir, particularly for heavy REEs. Conventional lab-based REE exploration restricts rapid and large-scale assessment, whereas hyperspectral imaging provides a promising approach for quantitative evaluation. This study evaluates the capacity of hyperspectral data for the quantitative determination of REEs in marine sediments. A total of 53 samples from various locations were analyzed to determine their chemical composition and spectral characteristics within the 380–1000 nm range under natural light. The influence of surface conditions on spectral integrity was evaluated, and multiple preprocessing and spectral feature extraction methods were applied to enhance data reliability. This study proposes a novel approach, termed Feature Importance within Pearson Correlation Coefficient-Based High-Correlation Spectral Range (PCCR-FI), designed for the identification of characteristic spectral bands associated with REEs. Machine learning models were subsequently constructed to estimate REE concentrations, and the following key findings were observed: (a) technical adjustments effectively addressed variations in sediment surface conditions, ensuring data reliability. (b) The PCCR-FI technique identified characteristic REEs spectral bands, enhancing processing efficiency and prediction accuracy. (c) The integration of the reciprocal logarithmic first derivative (TLOG-FD) technique with a multilayer perceptron (MLP) model, termed TLOG-FD-MLP, efficiently captured critical spectral features, resulting in improved prediction accuracy. For light REEs, the model achieved coefficient of determination (R²) values exceeding 0.60 and relative performance deviation (RPD) values exceeding 1.60, with some elements demonstrating R² values as high as 0.81 with RPD values surpassing 2.00. Furthermore, several heavy REEs exhibited moderate prediction performance, with R² values consistently exceeding 0.60. When considering the total REE content, an R² of 0.73 and an RPD of 1.97 were achieved. These findings demonstrate the use of hyperspectral imaging as a viable tool for quantitative evaluation of REE concentrations in marine sediments, providing valuable guidance for resource mapping and the exploration of seafloor polymetallic deposits. Full article

(This article belongs to the Special Issue Critical Mineral Exploration: Innovations, Challenges and Future Directions)

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26 pages, 1979 KB

Open AccessReview

From Single-Sensor Constraints to Multisensor Integration: Advancing Sustainable Complex Ore Sorting

by Sefiu O. Adewuyi, Angelina Anani, Kray Luxbacher and Sehliselo Ndlovu

Minerals 2025, 15(11), 1101; https://doi.org/10.3390/min15111101 - 23 Oct 2025

Abstract

Processing complex ore remains a challenge due to energy-intensive grinding and complex beneficiation and pyrometallurgical treatments that consume large amounts of water whilst generating significant waste and polluting the environment. Sensor-based ore sorting, which separates ore particles based on their physical or chemical [...] Read more.

Processing complex ore remains a challenge due to energy-intensive grinding and complex beneficiation and pyrometallurgical treatments that consume large amounts of water whilst generating significant waste and polluting the environment. Sensor-based ore sorting, which separates ore particles based on their physical or chemical properties before downstream processing, is emerging as a transformative technology in mineral processing. However, its application to complex and heterogeneous ores remain limited by the constraints of single-sensor systems. In addition, existing hybrid sensor strategies are fragmented and a consolidated framework for implementation is lacking. This review explores these challenges and underscores the potential of multimodal sensor integration for complex ore pre-concentration. A multi-sensor framework integrating machine learning and computer vision is proposed to overcome limitations in handling complex ores and enhance sorting efficiency. This approach can improve recovery rates, reduce energy and water consumption, and optimize process performance, thereby supporting more sustainable mining practices that contribute to the United Nations Sustainable Development Goals (UNSDGs). This work provides a roadmap for advancing efficient, resilient, and next-generation mineral processing operations. Full article

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

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18 pages, 4149 KB

Open AccessArticle

Enhanced Chromite Recovery from Tailings via a Custom-Designed Shaking Table: Optimization and Performance

by Savas Ozun and Ahmet Kerim Guraslan

Minerals 2025, 15(11), 1100; https://doi.org/10.3390/min15111100 - 23 Oct 2025

Abstract

Significant chromite losses to tailings in gravity separation plants arise from both suboptimal separator design and inefficient beneficiation processes, posing major challenges to resource utilization, energy efficiency, and environmental sustainability. These losses are particularly critical because the material, already comminuted to liberation size, [...] Read more.

Significant chromite losses to tailings in gravity separation plants arise from both suboptimal separator design and inefficient beneficiation processes, posing major challenges to resource utilization, energy efficiency, and environmental sustainability. These losses are particularly critical because the material, already comminuted to liberation size, is discarded, leading to reduced concentrate yield, wasted energy input, and increased environmental pollution. To address this issue, an industrial-scale custom-designed shaking table was developed and tested to recover marketable-grade chromite concentrate (≥42% Cr₂O₃) from processing plant tailings containing 3.25%–4.25% Cr₂O₃, which had accumulated over years of chromite beneficiation. Experimental results showed that, under optimized operating parameters (320 rpm stroke frequency, 13 mm stroke length, 1° deck slope, 1300 g/L pulp density, 800 kg/h feed rate, and 7 tph wash water flow rate), Cr₂O₃ recovery increased from 8% to 27% for the first and second floor operations and from approximately 17% to 41% for the third and fourth floor operations compared with existing plant performance. The results revealed a strong interdependence between Cr₂O₃ recovery and concentrate grade, both of which are critical indicators of process efficiency. Intermediate particle sizes (−0.250 + 0.150 mm) provided the most favorable balance, yielding high recovery rates without substantially compromising the concentrated grade. Full article

(This article belongs to the Special Issue Waste Valorization: Recycling and Recovery of Critical and Strategic Metals)

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16 pages, 3788 KB

Open AccessArticle

Color Genesis and Compositional Features of Red-Blue Colored Gem-Quality Corundum from Malipo, China

by Hui Wang, Xiao-Yan Yu, Guang-Ya Wang, Masroor Alam, Lan Mu, Ying-Xin Xu and Fei Liu

Minerals 2025, 15(11), 1099; https://doi.org/10.3390/min15111099 - 22 Oct 2025

Abstract

The newly discovered multi-colored corundum (gem quality) alluvial deposit in Malipo, Yunnan Province, is one of the most famous sapphire deposits in China. However, the coloration mechanism and genesis of red-blue colored corundum (RBCC) remain enigmatic. In this study, conventional gemological techniques such [...] Read more.

The newly discovered multi-colored corundum (gem quality) alluvial deposit in Malipo, Yunnan Province, is one of the most famous sapphire deposits in China. However, the coloration mechanism and genesis of red-blue colored corundum (RBCC) remain enigmatic. In this study, conventional gemological techniques such as ultraviolet–visible (UV-vis) spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were employed on an RBCC suite, with a view to unravel its coloration mechanism and compositional characteristics. The results show that the element pairs of Cr³⁺, Fe²⁺-Ti⁴⁺, and Fe³⁺-Fe³⁺ in principle contribute to the red coloration, while the blue color in corundum is predominantly caused by the Fe²⁺-Ti⁴⁺ pair, and subordinately by Cr³⁺ and Fe³⁺. Cr is likely the cause of the purple color. The Cr content in the red zone is significantly higher than that in the blue zone, while the Ti and V contents in the red zone are notably lower than in the blue zone. High Cr/Ga and (V + Cr)/Ga values of the Malipo RBCC suggest a metamorphic origin. All color zones of RBCC demonstrate stability in Ga content and an extremely low content of Mg, with minor fluctuations in Fe content, indicating that the formation process of the Malipo RBCC was influenced by magma mixing. Full article

(This article belongs to the Special Issue Gems Under the Microscope: New Insights into Mineral Structures and Properties)

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17 pages, 4946 KB

Open AccessArticle

From Waste to Sustainable Resource: Linking Phyllite Parent Rock Mineralogy to Suitability of Manufactured Sand for Concrete Construction

by Yanxiu Wang, Yang Li, Zhengxiang Liu, Yi Tian, Anqi Yang, Qiang Yuan, Xuekun Tang, Wei Sun, Qingchao Zhao and Mingyuan Wang

Minerals 2025, 15(11), 1098; https://doi.org/10.3390/min15111098 - 22 Oct 2025

Abstract

The expansion of copper mining operations has led to the accumulation of a large amount of phyllite waste rock. Re-purposing this material into manufactured sand presents a promising solution for its large-scale consumption. In this study, phyllite waste rock from the Dexing Copper [...] Read more.

The expansion of copper mining operations has led to the accumulation of a large amount of phyllite waste rock. Re-purposing this material into manufactured sand presents a promising solution for its large-scale consumption. In this study, phyllite waste rock from the Dexing Copper Mine was used as raw materials to prepare manufactured sand. A precise mineralogical analysis was conducted using Tescan Integrated Mineral Analyzer (TIMA) to determine the mineral composition, intergeneration and distribution relationships, particle size and shape, and elemental distribution. The performance of the resulting manufactured sand was comprehensively evaluated. Key findings showed a needle and flake particle content of 5.2%, a methylene blue (MB) value of 1.3, and a stone powder content of 9%. The physical properties, including solidity, crushing index, density, and porosity, as well as mica content, complied with the national standard GB14684-2022 (Sand for Construction). Additionally, phyllite-sand concrete exhibited a third-month expansion rate below the standard limit of 0.1%, indicating no potential risk for alkali-silica reaction. The radioactive index of the material met the standard requirements, posing no radiation hazard. However, the excessive sulfur compounds in phyllite present a risk of corrosion of the concrete structures, necessitating mitigation measures. Full article

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

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18 pages, 6111 KB

Open AccessArticle

Sustainable Removal of Heavy Metal Ions from Mineral Wastewater Using Waste Basalt Fiber

by Zhongyi Liu, Chenhu Zhang, Hexiang Zhong, Chengyong Wang, Peng Chen, Peng Zhang, Wei Ding and Shiwei Wang

Minerals 2025, 15(11), 1097; https://doi.org/10.3390/min15111097 - 22 Oct 2025

Abstract

Heavy metal ions in wastewater endanger ecology and human health, requiring cost-effective treatments. This study innovatively converts abandoned basalt fibers (BFs) into high-performance adsorbents (BFSN) via NaOH etching and chelation with nitrilotriacetic acid (NTA)/carboxymethyl starch (CMS), introducing target functional groups. Characterizations (XPS, FTIR, [...] Read more.

Heavy metal ions in wastewater endanger ecology and human health, requiring cost-effective treatments. This study innovatively converts abandoned basalt fibers (BFs) into high-performance adsorbents (BFSN) via NaOH etching and chelation with nitrilotriacetic acid (NTA)/carboxymethyl starch (CMS), introducing target functional groups. Characterizations (XPS, FTIR, zeta potential) reveal Cu²⁺/Pb²⁺ adsorption mechanisms: -COO⁻ chelation, N-containing group ion exchange, and electrostatic adsorption. Kinetics fit a pseudo-first-order model (R² > 0.98) and isotherms fit the Langmuir model, confirming monolayer chemisorption. BFSN has excellent thermal stability (≤2% mass loss at 800 °C) and post-adsorption integrity (≈0.11% mass loss post-loading). Waste-derived BFSN, cheaper than commercial adsorbents, has strong economic viability. This “waste-to-value” approach offers efficient, sustainable large-scale heavy metal wastewater remediation, advancing waste utilization and ecological restoration in water treatment. Full article

(This article belongs to the Special Issue Advanced Techniques in Mining Wastewater Treatment and Resource Recovery)

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16 pages, 4045 KB

Open AccessArticle

Carbonate Mineral Formation by Microalgae: Precipitation Potential and Morphological Analysis

by Hamed Abdeh Keykha, Sumit Joshi, Maria Mavroulidou, Hadi Mohamadzadeh Romiani and Afshin Asadi

Minerals 2025, 15(11), 1096; https://doi.org/10.3390/min15111096 - 22 Oct 2025

Abstract

This study evaluated the ability of microalgae to produce carbonate minerals through CO₂ uptake, in comparison with abiotic, direct chemical synthesis through CO₂ absorption. A freshwater microalga (Synechococcus elongatus) isolated from garden soil in East Anglia, UK, was cultivated [...] Read more.

This study evaluated the ability of microalgae to produce carbonate minerals through CO₂ uptake, in comparison with abiotic, direct chemical synthesis through CO₂ absorption. A freshwater microalga (Synechococcus elongatus) isolated from garden soil in East Anglia, UK, was cultivated under laboratory conditions with CO₂ injection to generate a bicarbonate-rich aqueous solution, in which Fe²⁺, Mg²⁺, and Ca²⁺ ions were added to facilitate carbonate formation. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses revealed distinct morphologies and mineral types. The algae-based process precipitated calcite, siderite, magnesite, and dolomite, whereas the abiotic process yielded, respectively, calcite, siderite, high-Mg calcite and nesquehonite. Biogenic minerals were finer and more morphologically diverse than their abiotically formed counterparts. The results indicated that microalgae produced 0.21 mol/L of calcium carbonate, compared to 0.51 mol/L obtained through abiotic CO₂ sequestration, and a comparable yield of about 0.25 mol/L reported for Sporosarcina pasteurii-induced precipitation. Acid resistance tests showed that algae-induced minerals had similar or improved resistance to acidic conditions compared to minerals formed through abiotic CO₂ consumption. Overall, despite slower kinetics, algae-induced carbonate precipitation offers advantages for soil stabilization by biocementation in the context of environmental sustainability, climate change mitigation and circular economy. Full article

(This article belongs to the Special Issue Exploring Novel Interactions Between Microbes and Minerals)

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18 pages, 2718 KB

Open AccessArticle

From a Scheelite Concentrate (Spanish Origin) to Nanotungsten Derivatives

by Francisco Jose Alguacil

Minerals 2025, 15(10), 1095; https://doi.org/10.3390/min15101095 - 21 Oct 2025

Abstract

Tungsten is a series of metals considered strategic by the European Union, so there is great interest in its recovery from both raw materials and secondary products. Within these raw materials, there are cassiterite deposits containing tungsten. It is from one of these [...] Read more.

Tungsten is a series of metals considered strategic by the European Union, so there is great interest in its recovery from both raw materials and secondary products. Within these raw materials, there are cassiterite deposits containing tungsten. It is from one of these deposits (located in the northwest of Spain) that after electrostatic separation, a scheelite concentrate (4.8% tungsten) has been obtained. This concentrate has been processed through two hydrometallurgical procedures. In one case, alkaline leaching in sodium carbonate medium is used to obtain sodium tungstate solutions, which in turn allows synthetic scheelite (calcium tungstate) or tungstic acid to be obtained. The second procedure, which uses acidic leaching (hydrochloric acid medium), yields tungstic acid as the final product. In all of the above cases, the experimental conditions to yield the best tungsten recovery rates are defined. The different products (sodium tungstate solutions and tungstic acid) afforded were used as precursors to yield synthetic scheelite and nanotungsten compounds as amorphous meta- and paratungstate salts and non-stoichiometric tungsten blue oxides. Full article

(This article belongs to the Special Issue Application of Nanomaterials in Mineral Processing)

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21 pages, 807 KB

Open AccessReview

From Solid to Solution: How Surface-Active Agents Influence Bioleaching Efficiency and Bacteria–Mineral Interactions

by Agnieszka Pawlowska and Krzysztof Jan Legawiec

Minerals 2025, 15(10), 1094; https://doi.org/10.3390/min15101094 - 21 Oct 2025

Abstract

The search for sustainable methods of metal recovery has led to increased interest in bioleaching as a sustainable alternative to traditional mineral processing. Despite the ecological benefits, the low bioprocess efficiency is limiting industrial applications. Surfactants offer a promising solution by modifying solid–liquid [...] Read more.

The search for sustainable methods of metal recovery has led to increased interest in bioleaching as a sustainable alternative to traditional mineral processing. Despite the ecological benefits, the low bioprocess efficiency is limiting industrial applications. Surfactants offer a promising solution by modifying solid–liquid interactions and improving metal extraction. The review summarizes the effect of surfactants, biosurfactants, polymers, and flotation reagents on the bioleaching efficiency of various mineral materials. It includes their impact on microbial activity, bacteria–mineral interactions, as well as mineral properties such as surface potential and hydrophobicity. Recent literature from the past decade is critically evaluated. Current knowledge limitations and future directions for the effective use of surface-active agents in metal bioextraction were discussed. Full article

(This article belongs to the Special Issue Bioleaching of Metals: Current Applications and Future Directions)

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